Change search
Refine search result
1234567 1 - 50 of 879
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Toneli, D. A.
    et al.
    Univ Fed Sao Paulo, Dept Sci & Technol, BR-12231280 Sao Jose Dos Campos, Brazil..
    Pessoa, R. S.
    Technol Inst Aeronaut, Dept Phys, BR-12228900 Sao Jose Dos Campos, Brazil..
    Roberto, M.
    Technol Inst Aeronaut, Dept Phys, BR-12228900 Sao Jose Dos Campos, Brazil..
    Gudmundsson, Jon Tomas
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics. Univ Iceland, Sci Inst, Dunhaga 3, IS-107 Reykjavik, Iceland.
    A global model study of low pressure high density CF4 discharge2019In: Plasma sources science & technology (Print), ISSN 0963-0252, E-ISSN 1361-6595, Vol. 28, no 2, article id 025007Article in journal (Refereed)
    Abstract [en]

    We present a revised reaction set for low pressure high density CF4 plasma modelling. A global model (volume averaged) was developed to study a CF4 discharge that includes the neutral species CF4, CF3, CF2, CF, F-2, F, and C, the metastable states CF(a(4)Sigma(-) ) and CF2(B-3(1)), the positive ions CF3+, CF2+, CF+, CF2+, F+ and C+, the negative ions CF3-, F-2(-), and F- and electrons. The main reactions that contribute to the production and loss of each species are pointed out with an emphasis on the radicals CF2, CF and F, the dominant positive ion CF3+, and the dominant negative ion F-. We find wall processes to have a significant influence on the discharge. The density of F-2 is high due to recombination of F atoms at the walls and the losses of the radicals F, CF, and CF3 are mainly through wall recombination. As the pressure is increased, F- becomes the dominant negative charged species. The discharge is found to be weakly electronegative below similar to 10 mTorr and the electronegativity decreases with increased absorbed power.

  • 2.
    Ström, Petter
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Petersson, Per
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Rubel, Marek
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Bergsåker, Henric
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Bykov, Igor
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Frassinetti, Lorenzo
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Garcia Carrasco, Alvaro
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Hellsten, Torbjörn
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Menmuir, Sheena
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Tholerus, Simon
    Weckmann, Armin
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics. KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Tolias, Panagiotis
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Ratynskaia, Svetlana V.
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Rachlew, Elisabeth
    KTH, School of Engineering Sciences (SCI), Physics, Atomic and Molecular Physics.
    Vallejos, Pablo
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Johnson, T.
    Stefanikova, E.
    Zhou, Y.
    Zychor, I.
    et al.,
    Analysis of deposited layers with deuterium and impurity elements on samples from the divertor of JET with ITER-like wall2019In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 516, p. 202-213Article in journal (Refereed)
    Abstract [en]

    Inconel-600 blocks and stainless steel covers for quartz microbalance crystals from remote corners in the JET-ILW divertor were studied with time-of-flight elastic recoil detection analysis and nuclear reaction analysis to obtain information about the areal densities and depth profiles of elements present in deposited material layers. Surface morphology and the composition of dust particles were examined with scanning electron microscopy and energy-dispersive X-ray spectroscopy. The analyzed components were present in JET during three ITER-like wall campaigns between 2010 and 2017. Deposited layers had a stratified structure, primarily made up of beryllium, carbon and oxygen with varying atomic fractions of deuterium, up to more than 20%. The range of carbon transport from the ribs of the divertor carrier was limited to a few centimeters, and carbon/deuterium co-deposition was indicated on the Inconel blocks. High atomic fractions of deuterium were also found in almost carbon-free layers on the quartz microbalance covers. Layer thicknesses up to more than 1 micrometer were indicated, but typical values were on the order of a few hundred nanometers. Chromium, iron and nickel fractions were less than or around 1% at layer surfaces while increasing close to the layer-substrate interface. The tungsten fraction depended on the proximity of the plasma strike point to the divertor corners. Particles of tungsten, molybdenum and copper with sizes less than or around 1 micrometer were found. Nitrogen, argon and neon were present after plasma edge cooling and disruption mitigation. Oxygen-18 was found on component surfaces after injection, indicating in-vessel oxidation. Compensation of elastic recoil detection data for detection efficiency and ion-induced release of deuterium during the measurement gave quantitative agreement with nuclear reaction analysis, which strengthens the validity of the results.

  • 3.
    Causa, F.
    et al.
    CNR, Ist Fis Plasma Piero Caldirola, Via R Cozzi 53, I-20125 Milan, Italy.;CNR, Ist Fis Plasma, Via R Cozzi 53, I-20125 Milan, Italy..
    Ratynskaia, Svetlana
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Tolias, Panagiotis
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Zito, P.
    ENEA, Fus & Nucl Safety Dept, CR Frascati, Via E Fermi 45, I-00044 Rome, Italy..
    Analysis of runaway electron expulsion during tokamak instabilities detected by a single-channel Cherenkov probe in FTU2019In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 59, no 4, article id 046013Article in journal (Refereed)
    Abstract [en]

    The expulsion of runaway electrons (REs) during different types of tokamak instabilities is analysed by means of a Cherenkov probe inserted into the scrape-off layer of the FTU tokamak. One such type of instability, the well-known tearing mode, is involved in disruptive plasma termination events, during which the risk of RE avalanche multiplication is highest. The second type, known as anomalous Doppler instability, influences RE dynamics by enhancing pitch angle scattering. Three scenarios are analysed here, characterised by different RE generation rates and mechanisms. The main conclusions are drawn from correlations between the Cherenkov probe and other diagnostics. In particular, the Cherenkov probe permits the detection of fast electron expulsion with a high level of detail, presenting peaks with 100% signal contrast during tearing mode growth and rotation, and sub-peak structures reflecting the interplay between the magnetic island formed by the tearing mode, RE diffusion during island rotation and the geometry of obstacles in the vessel. Correlations between the Cherenkov signal, hard x-ray emission and electron cyclotron emission reveal the impulsive development of the anomalous Doppler instability with instability rise time in the microsecond scale resolved by the high time-resolution of the Cherenkov probe.

  • 4.
    Keraudy, Julien
    et al.
    Linkoping Univ, Dept Phys, SE-58183 Linkoping, Sweden.;Oerlikon Surface Solut AG, Oerlikon Balzers, Iramali 18, LI-9496 Balzers, Liechtenstein..
    Viloan, Rommel Paulo B.
    Linkoping Univ, Dept Phys, SE-58183 Linkoping, Sweden..
    Raadu, Michael A.
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Brenning, Nils
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Lundin, Daniel
    Univ Paris Saclay, Univ Paris Sud, CNRS, LPGP,UMR 8578, F-91405 Orsay, France..
    Helmersson, Ulf
    Linkoping Univ, Dept Phys, SE-58183 Linkoping, Sweden..
    Bipolar HiPIMS for tailoring ion energies in thin film deposition2019In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 359, p. 433-437Article in journal (Refereed)
    Abstract [en]

    The effects of a positive pulse following a high-power impulse magnetron sputtering (HiPIMS) pulse are studied using energy-resolved mass spectrometry. This includes exploring the influence of a 200 mu s long positive voltage pulse (U-rev = 10-150 V) following a typical HiPIMS pulse on the ion-energy distribution function (IEDF) of the various ions. We find that a portion of the Ti+ flux is affected and gains an energy which corresponds to the acceleration over the full potential U-rev. The Ar+ IEDF on the other hand illustrates that a large fraction of the accelerated Ar+, gain energies corresponding to only a portion of U-rev. The Ti+ IEDFs are consistent with the assumption that practically all the TO-, that are accelerated during the reverse pulse, originates from a region adjacent to the target, in which the potential is uniformly increased with the applied potential U-rev while much of the Ar+ originates from a region further away from the target over which the potential drops from U-rev to a lower potential consistent with the plasma potential achieved without the application of U-rev. The deposition rate is only slightly affected and decreases with U-rev, reaching 90% at U-rev = 150 V. Both the Ti IEDF and the small deposition rate change indicate that the potential increase in the region close to the target is uniform and essentially free of electric fields, with the consequence that the motion of ions inside the region is not much influenced by the application of U-rev. In this situation, Ti will flow towards the outer boundary of the target adjacent region, with the momentum gained during the HiPIMS discharge pulse, independently of whether the positive pulse is applied or not. The metal ions that cross the boundary in the direction towards the substrate, and do this during the positive pulse, all gain an energy corresponding to the full positive applied potential U-rev.

  • 5. Tang, B. -B
    et al.
    Li, W. Y.
    Chinese Acad Sci, State Key Lab Space Weather, Natl Space Sci Ctr, Beijing, Peoples R China.;Swedish Inst Space Phys, Uppsala, Sweden..
    Graham, D. B.
    Swedish Inst Space Phys, Uppsala, Sweden..
    Rager, A. C.
    Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA.;NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Wang, C.
    Chinese Acad Sci, State Key Lab Space Weather, Natl Space Sci Ctr, Beijing, Peoples R China.;Univ Chinese Acad Sci, Coll Earth & Planetary Sci, Beijing, Peoples R China..
    Khotyaintsev, Yu. V.
    Swedish Inst Space Phys, Uppsala, Sweden..
    Lavraud, B.
    Univ Toulouse, Inst Rech Astrophys & Planetol, Toulouse, France..
    Hasegawa, H.
    Japan Aerosp Explorat Agcy, Inst Space & Astronaut Sci, Sagamihara, Kanagawa, Japan..
    Zhang, Y. -C
    Dai, L.
    Chinese Acad Sci, State Key Lab Space Weather, Natl Space Sci Ctr, Beijing, Peoples R China..
    Giles, B. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Dorelli, J. C.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Russell, C. T.
    Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90024 USA..
    Lindqvist, Per-Arne
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Ergun, R. E.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA..
    Burch, J. L.
    Southwest Res Inst, San Antonio, TX USA..
    Crescent-Shaped Electron Distributions at the Nonreconnecting Magnetopause: Magnetospheric Multiscale Observations2019In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 46, no 6, p. 3024-3032Article in journal (Refereed)
    Abstract [en]

    Crescent-shaped electron distributions perpendicular to the magnetic field are an important indicator of the electron diffusion region in magnetic reconnection. They can be formed by the electron finite gyroradius effect at plasma boundaries or by demagnetized electron motion. In this study, we present Magnetospheric Multiscale mission observations of electron crescents at the flank magnetopause on 20 September 2017, where reconnection signatures are not observed. These agyrotropic electron distributions are generated by electron gyromotion at the thin electron-scale magnetic boundaries of a magnetic minimum after magnetic curvature scattering. The variation of their angular range in the perpendicular plane is in good agreement with predictions. Upper hybrid waves are observed to accompany the electron crescents at all four Magnetospheric Multiscale spacecraft as a result of the beam-plasma instability associated with these agyrotropic electron distributions. This study suggests electron crescents can be more frequently formed at the magnetopause. Plain Language Summary In this study, we present Magnetospheric Multiscale mission observations of electron crescents at the flank magnetopause and these agyrotropic electron distributions are formed at thin electron-scale magnetic boundaries after electron pitch angle scattering by the curved magnetic field. These results suggest that agyrotropic electron distributions can be more frequently formed at the magnetopause: (1) magnetic reconnection is not necessary, although electron crescents are taken as one of the observational signatures of the electron diffusion region, and (2) agyrotropic electron distributions can cover a large local time range to the flank magnetopause. In addition, upper hybrid waves accompanied with the electron crescents are observed as a result of the beam-plasma interaction associated with these agyrotropic electron distributions. This suggests that high-frequency waves play a role in electron dynamics through wave-particle interactions.

  • 6.
    Labit, B.
    et al.
    Ecole Polytech Fed Lausanne, SPC, CH-1015 Lausanne, Switzerland..
    Frassinetti, Lorenzo
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Jonsson, Thomas
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Ratynskaia, Svetlana V.
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Thorén, Emil
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Tolias, Panagiotis
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Vallejos Olivares, Pablo
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Zuin, M.
    Consorzio RFX, Corso Stati Uniti 4, I-35127 Padua, Italy..
    Dependence on plasma shape and plasma fueling for small edge-localized mode regimes in TCV and ASDEX Upgrade2019In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 59, no 8, article id 086020Article in journal (Refereed)
    Abstract [en]

    Within the EUROfusion MST1 work package, a series of experiments has been conducted on AUG and TCV devices to disentangle the role of plasma fueling and plasma shape for the onset of small ELM regimes. On both devices, small ELM regimes with high confinement are achieved if and only if two conditions are fulfilled at the same time. Firstly, the plasma density at the separatrix must be large enough (n(e,sep)/n(G) similar to 0.3), leading to a pressure profile flattening at the separatrix, which stabilizes type-I ELMs. Secondly, the magnetic configuration has to be close to a double null (DN), leading to a reduction of the magnetic shear in the extreme vicinity of the separatrix. As a consequence, its stabilizing effect on ballooning modes is weakened.

  • 7.
    Kateb, Movaffaq
    et al.
    Univ Iceland, Inst Sci, Dunhaga 3, IS-107 Reykjavik, Iceland..
    Gudmundsson, Jon Tomas
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics. Univ Iceland, Inst Sci, Dunhaga 3, IS-107 Reykjavik, Iceland..
    Ingvarsson, Snorri
    Univ Iceland, Inst Sci, Dunhaga 3, IS-107 Reykjavik, Iceland..
    Effect of atomic ordering on the magnetic anisotropy of single crystal Ni80Fe202019In: AIP Advances, ISSN 2158-3226, E-ISSN 2158-3226, Vol. 9, no 3, article id 035308Article in journal (Refereed)
    Abstract [en]

    We investigate the effect of atomic ordering on the magnetic anisotropy of Ni80Fe20 at.% (Py). To this end, Py films were grown epitaxially on MgO(001) using dc magnetron sputtering (dcMS) and high power impulse magnetron sputtering (HiPIMS). Aside from twin boundaries observed in the latter case, both methods present high quality single crystals with cube-on-cube epitaxial relationship as verified by the polar mapping of important crystal planes. However, X-ray diffraction results indicate higher order for the dcMS deposited film towards L1(2) Ni3Fe superlattice. This difference can be understood by the very high deposition rate of HiPIMS during each pulse which suppresses adatom mobility and ordering. We show that the dcMS deposited film presents biaxial anisotropy while HiPIMS deposition gives well defined uniaxial anisotropy. Thus, higher order achieved in the dcMS deposition behaves as predicted by magnetocrystalline anisotropy i.e. easy axis along the [111] direction that forced in the plane along the [110] direction due to shape anisotropy. The uniaxial behaviour in HiPIMS deposited film then can be explained by pair ordering or more recent localized composition non-uniformity theories. Further, we studied magnetoresistance of the films along the [100] directions using an extended van der Pauw method. We find that the electrical resistivities of the dcMS deposited film are lower than in their HiPIMS counterparts verifying the higher order in the dcMS case.

  • 8.
    Sultan, M. T.
    et al.
    Reykjavik Univ, Sch Sci & Engn, IS-101 Reykjavik, Iceland..
    Gudmundsson, Jon Tomas
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics. Univ Iceland, Sci Inst, Dunhaga 3, IS-107 Reykjavik, Iceland..
    Manolescu, A.
    Reykjavik Univ, Sch Sci & Engn, IS-101 Reykjavik, Iceland..
    Teodorescu, V. S.
    Natl Inst Mat Phys, Magurele 077125, Romania..
    Ciurea, M. L.
    Natl Inst Mat Phys, Magurele 077125, Romania.;Acad Romanian Scientists, Bucharest 050094, Romania..
    Svavarsson, H. G.
    Reykjavik Univ, Sch Sci & Engn, IS-101 Reykjavik, Iceland..
    Efficacy of annealing and fabrication parameters on photo-response of SiGe in TiO2 matrix2019In: Nanotechnology, ISSN 0957-4484, E-ISSN 1361-6528, Vol. 30, no 36, article id 365604Article in journal (Refereed)
    Abstract [en]

    SiGe nanoparticles dispersed in a dielectric matrix exhibit properties different from those of bulk and have shown great potential in devices for application in advanced optoelectronics. Annealing is a common fabrication step used to increase crystallinity and to form nanoparticles in such a system. A frequent downside of such annealing treatment is the formation of insulating SiO2 layer at the matrix/SiGe interface, degrading the optical properties of the structure. An annealing process that could bypass this downside would therefore be of great interest. In this work, a short-time furnace annealing of a SiGe/TiO2 system is applied to obtain SiGe nanoparticles without formation of the undesired SiO2 layer between the dielectric matrix (TiO2) and SiGe. The structures were prepared by depositing alternate layers of TiO2 and SiGe films, using direct-current magnetron sputtering technique. A wide range spectral response with a response-threshold up to similar to 1300 nm was obtained, accompanied with an increase in photo-response of more than two-orders of magnitude. Scanning electron microscopy, transmission electron microscopy, energy-dispersive x-ray spectroscopy and grazing incidence x-ray diffraction were used to analyze the morphological changes in respective structures. Photoconductive properties were studied by measuring photocurrent spectra using applied dc-voltages at various temperatures.

  • 9. Chen, L. -J
    et al.
    Wang, S.
    Hesse, M.
    Ergun, R. E.
    Moore, T.
    Giles, B.
    Bessho, N.
    Russell, C.
    Burch, J.
    Torbert, R. B.
    Genestreti, K. J.
    Paterson, W.
    Pollock, C.
    Lavraud, B.
    Le Contel, O.
    Strangeway, R.
    Khotyaintsev, Y. V.
    Lindqvist, Per-Arne
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Electron Diffusion Regions in Magnetotail Reconnection Under Varying Guide Fields2019In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 46, no 12, p. 6230-6238Article in journal (Refereed)
    Abstract [en]

    Kinetic structures of electron diffusion regions (EDRs) under finite guide fields in magnetotail reconnection are reported. The EDRs with guide fields 0.14–0.5 (in unit of the reconnecting component) are detected by the Magnetospheric Multiscale spacecraft. The key new features include the following: (1) cold inflowing electrons accelerated along the guide field and demagnetized at the magnetic field minimum while remaining a coherent population with a low perpendicular temperature, (2) wave fluctuations generating strong perpendicular electron flows followed by alternating parallel flows inside the reconnecting current sheet under an intermediate guide field, and (3) gyrophase bunched electrons with high parallel speeds leaving the X-line region. The normalized reconnection rates for the three EDRs range from 0.05 to 0.3. The measurements reveal that finite guide fields introduce new mechanisms to break the electron frozen-in condition.

  • 10.
    Zhou, M.
    et al.
    Nanchang Univ, Inst Space Sci & Technol, Nanchang 330031, Jiangxi, Peoples R China.;Nanchang Univ, Sch Environm & Chem Engn, Minist Educ, Key Lab Poyang Lake Environm & Resource Utilizat, Nanchang 330031, Jiangxi, Peoples R China..
    Huang, J.
    Nanchang Univ, Inst Space Sci & Technol, Nanchang 330031, Jiangxi, Peoples R China.;Nanchang Univ, Sch Sci, Dept Phys, Nanchang 330031, Jiangxi, Peoples R China..
    Man, H. Y.
    Nanchang Univ, Inst Space Sci & Technol, Nanchang 330031, Jiangxi, Peoples R China.;Nanchang Univ, Sch Sci, Dept Phys, Nanchang 330031, Jiangxi, Peoples R China..
    Deng, X. H.
    Nanchang Univ, Inst Space Sci & Technol, Nanchang 330031, Jiangxi, Peoples R China..
    Zhong, Z. H.
    Nanchang Univ, Inst Space Sci & Technol, Nanchang 330031, Jiangxi, Peoples R China.;Nanchang Univ, Sch Resources Environm & Chem Engn, Nanchang 330031, Jiangxi, Peoples R China..
    Russell, C. T.
    Univ Calif Los Angeles, Dept Earth Planetary & Space Sci, Los Angeles, CA USA..
    Paterson, W. R.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA..
    Giles, B. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA..
    Lindqvist, Per-Arne
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics. Royal Inst Technol, SE-75121 Stockholm, Sweden..
    Khotyaintsev, Y. , V
    Burch, J. L.
    Southwest Res Inst, San Antonio, TX 78238 USA..
    Electron-scale Vertical Current Sheets in a Bursty Bulk Flow in the Terrestrial Magnetotail2019In: Astrophysical Journal Letters, ISSN 2041-8205, E-ISSN 2041-8213, Vol. 872, no 2, article id L26Article in journal (Refereed)
    Abstract [en]

    We report Magnetospheric Multiscale observations of multiple vertical current sheets (CSs) in a bursty bulk flow in the near-Earth magnetotail. Two of the CSs were fine structures of a dipolarization front (DF) at the leading edge of the flow. The other CSs were a few Earth radii tailward of the DF; that is, in the wake of the DF. Some of these vertical CSs were a few electron inertial lengths thick and were converting energy from magnetic field to plasma. The currents of the CSs in the DF wake were carried by electrons that formed flow shear layers. These electron-scale CSs were probably formed during the turbulent evolution of the bursty bulk flow and are important for energy conversion associated with fast flows.

  • 11.
    Trier, E.
    et al.
    Max Planck Inst Plasma Phys, D-85748 Garching, Germany..
    Frassinetti, Lorenzo
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Fridström, Richard
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Garcia Carrasco, Alvaro
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Hellsten, Torbjörn
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Johnson, Thomas
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Petersson, Per
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Ratynskaia, Svetlana V.
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Tolias, Panagiotis
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Vallejos, Pablo
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Vignitchouk, Ladislas
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Zuin, M.
    Consorzio RFX, Corso Stati Uniti 4, I-35127 Padua, Italy..
    ELM-induced cold pulse propagation in ASDEX Upgrade2019In: Plasma Physics and Controlled Fusion, ISSN 0741-3335, E-ISSN 1361-6587, Vol. 61, no 4, article id 045003Article in journal (Refereed)
    Abstract [en]

    In ASDEX Upgrade, the propagation of cold pulses induced by type-I edge localized modes (ELMs) is studied using electron cyclotron emission measurements, in a dataset of plasmas with moderate triangularity. It is found that the edge safety factor or the plasma current are the main determining parameters for the inward penetration of the T-e perturbations. With increasing plasma current the ELM penetration is more shallow in spite of the stronger ELMs. Estimates of the heat pulse diffusivity show that the corresponding transport is too large to be representative of the inter-ELM phase. Ergodization of the plasma edge during ELMs is a possible explanation for the observed properties of the cold pulse propagation, which is qualitatively consistent with non-linear magneto-hydro-dynamic simulations.

  • 12. Vines, S. K.
    et al.
    Allen, R. C.
    Anderson, B. J.
    Engebretson, M. J.
    Fuselier, S. A.
    Russell, C. T.
    Strangeway, R. J.
    Ergun, R. E.
    Lindqvist, Per-Arne
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Torbert, R. B.
    Burch, J. L.
    EMIC Waves in the Outer Magnetosphere: Observations of an Off-Equator Source Region2019In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 46, no 11, p. 5707-5716Article in journal (Refereed)
    Abstract [en]

    Electromagnetic ion cyclotron (EMIC) waves at large L shells were observed away from the magnetic equator by the Magnetospheric MultiScale (MMS) mission nearly continuously for over four hours on 28 October 2015. During this event, the wave Poynting vector direction systematically changed from parallel to the magnetic field (toward the equator), to bidirectional, to antiparallel (away from the equator). These changes coincide with the shift in the location of the minimum in the magnetic field in the southern hemisphere from poleward to equatorward of MMS. The local plasma conditions measured with the EMIC waves also suggest that the outer magnetospheric region sampled during this event was generally unstable to EMIC wave growth. Together, these observations indicate that the bidirectionally propagating wave packets were not a result of reflection at high latitudes but that MMS passed through an off-equator EMIC wave source region associated with the local minimum in the magnetic field.

  • 13. Sultan, M. T.
    et al.
    Gudmundsson, Jon Tomas
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Manolescu, A.
    Stoica, T.
    Ciurea, M. L.
    Svavarsson, H. G.
    Enhanced photoconductivity of embedded SiGe nanoparticles by hydrogenation2019In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 479, p. 403-409Article in journal (Refereed)
    Abstract [en]

    We investigate the effect of room-temperature hydrogen-plasma treatment on the photoconductivity of SiGe nanoparticles sandwiched within SiO 2 layers. An increase in photocurrent intensity of more than an order magnitude is observed after the hydrogen plasma treatment. The enhancement is attributed to neutralization of dangling bonds at the nanoparticles and to passivation of nonradiative defects in the oxide matrix and at SiGe/matrix interfaces. We find that increasing the partial pressure of hydrogen to pressures where H 3 + and H 2 + were the dominant ions results in increased photocurrent.

  • 14.
    Sultan, Muhammad Taha
    et al.
    Reykjav Univ, Sch Sci & Engn, IS-101 Reykjavik, Iceland..
    Manolescu, Andrei
    Reykjav Univ, Sch Sci & Engn, IS-101 Reykjavik, Iceland..
    Gudmundsson, Jon Tomas
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Torfason, Kristinn
    Reykjav Univ, Sch Sci & Engn, IS-101 Reykjavik, Iceland..
    Nemnes, George Alexandru
    Univ Bucharest, Fac Phys, MDEO Res Ctr, Magurele 077125, Romania..
    Stavarache, Ionel
    Natl Inst Mat Phys, Magurele 077125, Romania..
    Logofatu, Constantin
    Natl Inst Mat Phys, Magurele 077125, Romania..
    Teodoresu, Valentin Serban
    Natl Inst Mat Phys, Magurele 077125, Romania..
    Giurea, Magdalena Lidia
    Natl Inst Mat Phys, Magurele 077125, Romania.;Acad Romanian Scientists, Bucharest 050094, Romania..
    Svavarsson, Halldor Gudfinnur
    Reykjav Univ, Sch Sci & Engn, IS-101 Reykjavik, Iceland..
    Enhanced photoconductivity of SiGe nanocrystals in SiO2 driven by mild annealing2019In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 469, p. 870-878Article in journal (Refereed)
    Abstract [en]

    Photosensitive films based on finely dispersed semiconductor nanocrystals (NCs) in dielectric films have great potential for sensor applications. Here we report on preparation and characterization of photosensitive Si1-xGex NCs sandwiched between SiO2 matrix. A radio-frequency magnetron sputtering was applied to obtain a multilayer-structures (MLs) by depositing SiO2/SiGe/SiO2 films on Si (0 0 1) substrate. The Si1-xGex NCs were formed by a post-deposition annealing at 100-700 degrees C for 1-5 min. The effect of annealing temperature and time on MLs morphology and NCs size and density was studied using grazing incidence X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy and measurements of spectral distribution of photocurrent. It is demonstrated how the photoconductive properties of the MLs can be enhanced and tailored by controlling the NCs formation conditions and the presence of stress field in MLs and defects acting as traps and recombination centers. All these features can be adjusted/controlled by altering the annealing conditions (temperature and time). The MLs photosensitivity was increased of more than an order of magnitude by the annealing process. A mechanism, where a competition between crystallization process (NCs formation and evolution i.e. size and shapes) and stress field appearance determines the peak position in the photocurrent spectra, was identified.

  • 15.
    Fu, H. S.
    et al.
    Beihang Univ, Sch Space & Environm, Beijing, Peoples R China.
    Cao, J. B.
    Beihang Univ, Sch Space & Environm, Beijing, Peoples R China.
    Cao, D.
    Beihang Univ, Sch Space & Environm, Beijing, Peoples R China.
    Wang, Z.
    Beihang Univ, Sch Space & Environm, Beijing, Peoples R China.
    Vaivads, Andris
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics. Uppsala universitet, Institutet för rymdfysik, Uppsalaavdelningen.
    Khotyaintsev, Yuri V.
    Uppsala universitet, Institutet för rymdfysik, Uppsalaavdelningen.
    Burch, J. L.
    Southwest Res Inst, San Antonio, TX USA.
    Huang, S. Y.
    Wuhan Univ, Sch Elect & Informat, Wuhan, Hubei, Peoples R China.
    Evidence of Magnetic Nulls in Electron Diffusion Region2019In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 46, no 1, p. 48-54Article in journal (Refereed)
    Abstract [en]

    Theoretically, magnetic reconnection—the process responsible for solar flares and magnetospheric substorms—occurs at the X‐line or radial null in the electron diffusion region (EDR). However, whether this theory is correct is unknown, because the radial null (X‐line) has never been observed inside the EDR due to the lack of efficient techniques and the scarcity of EDR measurements. Here we report such evidence, using data from the recent MMS mission and the newly developed First‐Order Taylor Expansion (FOTE) Expansion technique. We investigate 12 EDR candidates at the Earth's magnetopause and find radial nulls (X‐lines) in all of them. In some events, spacecraft are only 3 km (one electron inertial length) away from the null. We reconstruct the magnetic topology of these nulls and find it agrees well with theoretical models. These nulls, as reconstructed for the first time inside the EDR by the FOTE technique, indicate that the EDR is active and the reconnection process is ongoing.

    Plain Language Summary: Magnetic reconnection is a key process responsible for many explosive phenomena in nature such as solar flares and magnetospheric substorms. Theoretically, such process occurs at the X‐line or radial null in the electron diffusion region (EDR). However, whether this theory is correct is still unknown, because the radial null (X‐line) has never been observed inside the EDR due to the lack of efficient technique and the scarcity of EDR measurements. Here we report such evidence, using data from the recent MMS mission and the newly developed FOTE technique.

  • 16.
    Sultan, Muhammad Taha
    et al.
    Reykjavik Univ, Sch Sci & Engn, IS-101 Reykjavik, Iceland..
    Maraloiu, Adrian Valentin
    Natl Inst Mat Phys, Magurele 077125, Romania..
    Stavarache, Ionel
    Natl Inst Mat Phys, Magurele 077125, Romania..
    Gudmundsson, Jon Tomas
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics. Univ Iceland, Sci Inst, Dunhaga 3, IS-107 Reykjavik, Iceland..
    Manolescu, Andrei
    Reykjavik Univ, Sch Sci & Engn, IS-101 Reykjavik, Iceland..
    Teodorescu, Valentin Serban
    Natl Inst Mat Phys, Magurele 077125, Romania.;Acad Romanian Scientists, Bucharest 050094, Romania..
    Ciurea, Magdalena Lidia
    Natl Inst Mat Phys, Magurele 077125, Romania.;Acad Romanian Scientists, Bucharest 050094, Romania..
    Svavarsson, Halldor Gudfinnur
    Reykjavik Univ, Sch Sci & Engn, IS-101 Reykjavik, Iceland..
    Fabrication and characterization of Si1-xGex nanocrystals in as-grown and annealed structures: a comparative study2019In: Beilstein Journal of Nanotechnology, ISSN 2190-4286, Vol. 10, p. 1873-1882Article in journal (Refereed)
    Abstract [en]

    Multilayer structures comprising of SiO2/SiGe/SiO2 and containing SiGe nanoparticles were obtained by depositing SiO2 layers using reactive direct current magnetron sputtering (dcMS), whereas, Si and Ge were co-sputtered using dcMS and high-power impulse magnetron sputtering (HiPIMS). The as-grown structures subsequently underwent rapid thermal annealing (550-900 degrees C for 1 min) in N-2 ambient atmosphere. The structures were investigated using X-ray diffraction, high-resolution transmission electron microscopy together with spectral photocurrent measurements, to explore structural changes and corresponding properties. It is observed that the employment of HiPIMS facilitates the formation of SiGe nanoparticles (2.1 +/- 0.8 nm) in the as-grown structure, and that presence of such nanoparticles acts as a seed for heterogeneous nucleation, which upon annealing results in the periodically arranged columnar self-assembly of SiGe core-shell nanocrystals. An increase in photocurrent intensity by more than an order of magnitude was achieved by annealing. Furthermore, a detailed discussion is provided on strain development within the structures, the consequential interface characteristics and its effect on the photocurrent spectra.

  • 17.
    Torkar, K.
    et al.
    Austrian Acad Sci, Space Res Inst, A-8042 Graz, Austria..
    Nakamura, R.
    Austrian Acad Sci, Space Res Inst, A-8042 Graz, Austria..
    Wellenzohn, S.
    Austrian Acad Sci, Space Res Inst, A-8042 Graz, Austria..
    Jeszenszky, H.
    Austrian Acad Sci, Space Res Inst, A-8042 Graz, Austria..
    Torbert, R. B.
    Univ New Hampshire, Space Sci Ctr, Durham, NH 03824 USA..
    Lindqvist, Per-Arne
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Ergun, R. E.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80303 USA..
    Giles, B. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA..
    Improved Determination of Plasma Density Based on Spacecraft Potential of the Magnetospheric Multiscale Mission Under Active Potential Control2019In: IEEE Transactions on Plasma Science, ISSN 0093-3813, E-ISSN 1939-9375, Vol. 47, no 8, p. 3636-3647Article in journal (Refereed)
    Abstract [en]

    Data from the Magnetospheric Multiscale (MMS) mission, in particular, the spacecraft potential measured with and without the ion beams of the active spacecraft potential control (ASPOC) instruments, plasma electron moments, and the electric field, have been employed for an improved determination of plasma density based on spacecraft potential. The known technique to derive plasma density from spacecraft potential sees the spacecraft behaving as a plasma probe which adopts a potential at which the ambient plasma current and one of photoelectrons produced at the surface and leaving into space are in equilibrium. Thus, the potential is a function of the plasma current, and plasma density can be determined using measurements or assumptions on plasma temperature. This method is especially useful during periods when the plasma instruments are not in operation or when spacecraft potential data have significantly higher time resolution than particle detectors. However, the applicable current-voltage characteristic of the spacecraft has to be known with high accuracy, particularly when the potential is actively controlled and shows only minor residual variations. This paper demonstrates recent refinements of the density determination coming from: 1) the reduction of artifacts in the potential data due to the geometry of the spinning spacecraft and due to effects of the ambient electric field on the potential measurements and 2) a calibration of the plasma current to the spacecraft surfaces which is only possible by comparison with the variable currents from the ion beams of ASPOC. The results are discussed, and plasma densities determined by this method are shown in comparison with measurements by the Fast Plasma Instrument (FPI) for some intervals of the MMS mission.

  • 18. Goodrich, K. A.
    et al.
    Ergun, R.
    Schwartz, S. J.
    Wilson, L. B. , I I I
    Johlander, A.
    Newman, D.
    Wilder, F. D.
    Holmes, J.
    Burch, J.
    Torbert, R.
    Khotyaintsev, Y.
    Lindqvist, Per-Arne
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Strangeway, R.
    Gershman, D.
    Giles, B.
    Impulsively Reflected Ions: A Plausible Mechanism for Ion Acoustic Wave Growth in Collisionless Shocks2019In: Journal of Geophysical Research: Space Physics, Vol. 124, no 3, p. 1855-1865Article in journal (Refereed)
    Abstract [en]

    We present recent high time resolution observations from an oblique (43 degrees) shock crossing from the Magnetospheric Multiscale mission. Short-duration bursts between 10 and 100 ms of ion acoustic waves are observed in this event alongside a persistent reflected ion population. High time resolution (150 ms) particle measurements show strongly varying ion distributions between successive measurements, implying that they are bursty and impulsive by nature. Such signatures are consistent with ion bursts that are impulsively reflected at various points within the shock. We find that, after instability analysis using a Fried-Conte dispersion solver, the insertion of dispersive ion bursts into an already stable ion distribution can lead to wave growth in the ion acoustic mode for short durations of time. We find that impulsively reflected ions are a plausible mechanism for ion acoustic wave growth in the terrestrial bow shock and, furthermore, suggest that wave growth can lead to a small but measurable momentum exchange between the solar wind ions and the reflected population.

  • 19.
    Cozzani, Giulia
    et al.
    Univ Paris Sud, Sorbonne Univ, Observ Paris, Lab Phys Plasmas,CNRS,Ecole Polytech, F-91128 Palaiseau, France.;Univ Pisa, Dipartimento Fis E Fermi, I-56127 Pisa, Italy..
    Retino, A.
    Univ Paris Sud, Sorbonne Univ, Observ Paris, Lab Phys Plasmas,CNRS,Ecole Polytech, F-91128 Palaiseau, France..
    Califano, F.
    Univ Pisa, Dipartimento Fis E Fermi, I-56127 Pisa, Italy..
    Alexandrova, A.
    Univ Paris Sud, Sorbonne Univ, Observ Paris, Lab Phys Plasmas,CNRS,Ecole Polytech, F-91128 Palaiseau, France..
    Contel, O. Le
    Univ Paris Sud, Sorbonne Univ, Observ Paris, Lab Phys Plasmas,CNRS,Ecole Polytech, F-91128 Palaiseau, France..
    Khotyaintsev, Y.
    Swedish Inst Space Phys, SE-75121 Uppsala, Sweden..
    Vaivads, Andris
    Swedish Inst Space Phys, SE-75121 Uppsala, Sweden..
    Fu, H. S.
    Beihang Univ, Sch Space & Environm, Beijing 100083, Peoples R China..
    Catapano, F.
    Univ Paris Sud, Sorbonne Univ, Observ Paris, Lab Phys Plasmas,CNRS,Ecole Polytech, F-91128 Palaiseau, France.;Univ Calabria, Dipartimento Fis, I-87036 Arcavacata Di Rende, CS, Italy..
    Breuillard, H.
    Univ Paris Sud, Sorbonne Univ, Observ Paris, Lab Phys Plasmas,CNRS,Ecole Polytech, F-91128 Palaiseau, France.;Univ Orleans, UMR 7328, CNRS, Lab Phys & Chim Environm & Espace, F-45071 Orleans, France..
    Ahmadi, N.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA..
    Lindqvist, Per-Arne
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Ergun, R. E.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA..
    Torbert, R. B.
    Univ New Hampshire, Space Sci Ctr, Durham, NH 03824 USA..
    Giles, B. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA..
    Russell, C. T.
    Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90095 USA..
    Nakamura, R.
    Austrian Acad Sci, Space Res Inst, A-8042 Graz, Austria..
    Fuseher, S.
    Southwest Res Inst, San Antonio, TX 78238 USA.;Univ Texas San Antonio, San Antonio, TX 78238 USA..
    Mauk, B. H.
    Johns Hopkins Univ, Appl Phys Lab, Johns Hopkins Rd, Laurel, MD 20723 USA..
    Moore, T.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA..
    Burch, J. L.
    Southwest Res Inst, San Antonio, TX 78238 USA..
    In situ spacecraft observations of a structured electron diffusion region during magnetopause reconnection2019In: Physical review. E, ISSN 2470-0045, E-ISSN 2470-0053, Vol. 99, no 4, article id 043204Article in journal (Refereed)
    Abstract [en]

    The electron diffusion region (EDR) is the region where magnetic reconnection is initiated and electrons are energized. Because of experimental difficulties, the structure of the EDR is still poorly understood. A key question is whether the EDR has a homogeneous or patchy structure. Here we report Magnetospheric Multiscale (MMS) spacecraft observations providing evidence of inhomogeneous current densities and energy conversion over a few electron inertial lengths within an EDR at the terrestrial magnetopause, suggesting that the EDR can be rather structured. These inhomogenenities are revealed through multipoint measurements because the spacecraft separation is comparable to a few electron inertial lengths, allowing the entire MMS tetrahedron to be within the EDR most of the time. These observations are consistent with recent high-resolution and low-noise kinetic simulations.

  • 20.
    Retherford, K. D.
    et al.
    Southwest Res Inst, San Antonio, TX 78238 USA.;Univ Texas San Antonio, San Antonio, TX 78249 USA..
    Roth, Lorenz
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Becker, T. M.
    Southwest Res Inst, San Antonio, TX 78238 USA..
    Feaga, L. M.
    Univ Maryland, College Pk, MD 20742 USA..
    Tsang, C. C. C.
    Southwest Res Inst, Boulder, CO 80302 USA..
    Jessup, K. L.
    Southwest Res Inst, Boulder, CO 80302 USA..
    Grava, C.
    Southwest Res Inst, San Antonio, TX 78238 USA..
    Io's Atmosphere Silhouetted by Jupiter Ly alpha2019In: Astronomical Journal, ISSN 0004-6256, E-ISSN 1538-3881, Vol. 158, no 4, article id 154Article in journal (Refereed)
    Abstract [en]

    We report results from a new technique for mapping Io's SO2 vapor distribution. The Space Telescope Imaging Spectrograph (STIS) instrument on the Hubble Space Telescope observed Io during four Jupiter transit events to obtain medium resolution far-UV spectral images near the Ly alpha wavelength of 121.6 nm. Jupiter's bright Ly alpha dayglow provides a bright, mostly uniform background light source for opacity measurements, much like during a stellar occultation or transiting exoplanet event. Peaks in the photoabsorption cross-sections for sulfur dioxide occur near 122 nm, with resulting absorptions raising the altitude where a tangential line-of-sight opacity of similar to 1 occurs. This method of measuring column densities along lines of sight above the limb uses detailed image simulations and complements Ly alpha reflectance imaging and other methods for measuring Io's SO2 gas on the disk. Our reported near-terminator limb observations with STIS confirm the findings from previous Ly alpha disk reflectance imaging that Io's polar SO2 density is an order of magnitude lower than found at the equator. We provide constraints for additional attenuation by atmospheric hydrogen atoms produced by charge exchange reactions between magnetospheric protons and Io's atmosphere. Searches for plume-related features provided no definitive enhancements within the signal quality, ruling out unusually high levels of activity for Pele and Tvashtar.

  • 21.
    Lucco Castello, Federico
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Tolias, Panagiotis
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Hansen, Jesper Schmidt
    Dyre, Jeppe C.
    Isomorph invariance and thermodynamics of repulsive dense bi-Yukawa one-component plasmas2019In: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 26, no 5, article id 053705Article in journal (Refereed)
    Abstract [en]

    In numerous realizations of complex plasmas, dust-dust interactions are characterized by two screening lengths and are thus better described by a combination of Yukawa potentials. The present work investigates the static correlations and the thermodynamics of repulsive dense bi-Yukawa fluids based on the fact that such strongly coupled systems exhibit isomorph invariance. The strong virial-potential energy correlations are demonstrated with the aid of molecular dynamics simulations, an accurate analytical expression for the isomorph family of curves is obtained, and an empirical expression for the fluid-solid phase-coexistence line is proposed. The isomorph-based empirically modified hypernetted-chain approach, grounded on the ansatz of isomorph invariant bridge functions, is then extended to such systems and the resulting structural properties show an excellent agreement with the results of computer simulations. A simple and accurate closed-form expression is obtained for the excess internal energy of dense bi-Yukawa fluids by capitalizing on the compact parameterization offered by the Rosenfeld-Tarazona decomposition in combination with the Rosenfeld scaling, which opens up the energy route to thermodynamics.

  • 22.
    Tolias, Panagiotis
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Castello, F. Lucco
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Isomorph-based empirically modified hypernetted-chain approach for strongly coupled Yukawa one-component plasmas2019In: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 26, no 4, article id 043703Article in journal (Refereed)
    Abstract [en]

    Isomorph theory is employed in order to establish a mapping between the bridge function of Coulomb and Yukawa one-component plasmas. Within an exact invariance ansatz for the bridge functions and by capitalizing on the availability of simulation-extracted Coulomb bridge functions, an analytical Yukawa bridge function is derived which is inserted into the integral theory framework. In spite of its simplicity and computational speed, the proposed integral approach exhibits an excellent agreement with computer simulations of dense Yukawa liquids without invoking adjustable parameters. 

  • 23.
    Hue, V
    et al.
    Southwest Res Inst, San Antonio, TX 78238 USA..
    Greathouse, T. K.
    Southwest Res Inst, San Antonio, TX 78238 USA..
    Bonfond, B.
    Univ Liege, STAR Inst, LPAP, Liege, Belgium..
    Saur, J.
    Univ Cologne, Inst Geophys & Meteorol, Cologne, Germany..
    Gladstone, G. R.
    Southwest Res Inst, San Antonio, TX 78238 USA.;Univ Texas San Antonio, Dept Phys & Astron, San Antonio, TX USA..
    Roth, Lorenz
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Davis, M. W.
    Southwest Res Inst, San Antonio, TX 78238 USA..
    Gerard, J-C
    Univ Liege, STAR Inst, LPAP, Liege, Belgium..
    Grodent, D. C.
    Univ Liege, STAR Inst, LPAP, Liege, Belgium..
    Kammer, J. A.
    Southwest Res Inst, San Antonio, TX 78238 USA..
    Szalay, J. R.
    Princeton Univ, Dept Astrophys Sci, Princeton, NJ 08544 USA..
    Versteeg, M. H.
    Southwest Res Inst, San Antonio, TX 78238 USA..
    Bolton, S. J.
    Southwest Res Inst, San Antonio, TX 78238 USA..
    Connerney, J. E. P.
    Space Res Corp, Annapolis, MD USA.;NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Levin, S. M.
    Jet Prop Lab, Pasadena, CA USA..
    Hinton, P. C.
    Southwest Res Inst, San Antonio, TX 78238 USA.;Univ Colorado, Lab Atmosphere & Space Phys, Boulder, CO 80309 USA..
    Bagenal, F.
    Southwest Res Inst, San Antonio, TX 78238 USA.;Univ Colorado, Lab Atmosphere & Space Phys, Boulder, CO 80309 USA..
    Juno-UVS Observation of the Io Footprint During Solar Eclipse2019In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 124, no 7, p. 5184-5199Article in journal (Refereed)
    Abstract [en]

    The two main ultraviolet-signatures resulting from the Io-magnetosphere interaction are the local auroras on Io's atmosphere, and the Io footprints on Jupiter. We study here how Io's daily eclipses affect the footprint. Previous observations showed that its atmosphere collapses in eclipse. While remote observers can observe Io's local auroras briefly when Io disappears behind Jupiter, Juno is able to follow the Io footprint in the unlit hemisphere. Theoretical models of the variability of the energy flux fed into the Alfven wings, ultimately powering the footprints, are not sufficiently constrained by observations. For the first time, we use observations of Io's footprint from the Ultraviolet Spectrograph (UVS) on Juno recorded as Io went into eclipse. We benchmark the trend of the footprint brightness using observations by UVS taken over Io's complete orbit and find that the footprint emitted power variation with Jupiter's rotation shows fairly consistent trends with previous observations. Two exploitable data sets provided measurements when Io was simultaneously in eclipse. No statistically significant changes were recorded as Io left and moved into eclipse, respectively, suggesting either that (i) Io's atmospheric densities within and outside eclipse are large enough to produce a saturated plasma interaction, that is, in the saturated state, changes in Io's atmospheric properties to first order do not control the total Alfvenic energy flux, (ii) the atmospheric collapse during the Juno observations was less than previously observed, or (iii) additional processes of the Alfven wings in addition to the Poynting flux generated at Io control the footprint luminosity.

  • 24. Li, B.
    et al.
    Han, D. -S
    Hu, Z. -J
    Hu, H. -Q
    Liu, J. -J
    Dai, L.
    Liu, H.
    Escoubet, C. P.
    Dunlop, M. W.
    Ergun, R. E.
    Lindqvist, Per-Arne
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Torbert, R. B.
    Russell, C. T.
    Magnetospheric Multiscale Observations of ULF Waves and Correlated Low-Energy Ion Monoenergetic Acceleration2019In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402Article in journal (Refereed)
    Abstract [en]

    Low-energy ions of ionospheric origin with energies below 10s of electron volt dominate most of the volume and mass of the terrestrial magnetosphere. However, sunlit spacecraft often become positively charged to several 10s of volts, which prevents low-energy ions from reaching the particle detectors on the spacecraft. Magnetospheric Multiscale spacecraft (MMS) observations show that ultralow-frequency (ULF) waves drive low-energy ions to drift in the E × B direction with a drift velocity equal to V E × B , and low-energy ions were accelerated to sufficient total energy to be measured by the MMS/Fast Plasma Investigation Dual Ion Spectrometers. The maximum low-energy ion energy flux peak seen in MMS1's dual ion spectrometer measurements agreed well with the theoretical calculation of H + ion E × B drift energy. The density of ions in the energy range below minimum energy threshold was between 1 and 3 cm −3 in the magnetosphere subsolar region in this event.

  • 25.
    Alm, Love
    et al.
    Swedish Inst Space Phys, Uppsala, Sweden..
    Andre, Mats
    Swedish Inst Space Phys, Uppsala, Sweden..
    Graham, Daniel B.
    Swedish Inst Space Phys, Uppsala, Sweden..
    Khotvaintsev, Yuri, V
    Swedish Inst Space Phys, Uppsala, Sweden..
    Vaivads, Andris
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Chappell, Charles R.
    Vanderbilt Univ, Dept Phys & Astron, Vanderbilt Dyer Observ, Nashville, TN 37235 USA..
    Dargent, Jeremy
    Univ Pisa, Phys Dept Enrico Fermi, Pisa, Italy..
    Fuselier, Stephen A.
    Southwest Res Inst, San Antonio, TX USA.;Univ Texas San Antonio, Dept Phys & Astron, San Antonio, TX USA..
    Haaland, Stein
    Max Planck Inst Solar Syst Res, Gottingen, Germany.;Univ Bergen, Birkeland Ctr Space Sci, Bergen, Norway..
    Lavraud, Benoit
    Univ Toulouse, Inst Rech Astrophys & Planetol, CNRS, UPS,CNES, Toulouse, France..
    Li, Wenya
    Chinese Acad Sci, Natl Space Sci Ctr, State Key Lab Space Weather, Beijing, Peoples R China..
    Tenfjord, Paul
    Univ Bergen, Birkeland Ctr Space Sci, Bergen, Norway..
    Toledo-Redondo, Sergio
    Univ Toulouse, Inst Rech Astrophys & Planetol, CNRS, UPS,CNES, Toulouse, France..
    Vines, Sarah K.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA..
    MMS Observations of Multiscale Hall Physics in the Magnetotail2019In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007Article in journal (Refereed)
    Abstract [en]

    We present Magnetospheric Multiscale mission (MMS) observations of Hall physics in the magnetotail, which compared to dayside Hall physics is a relatively unexplored topic. The plasma consists of electrons, moderately cold ions (T similar to 1.5 keV) and hot ions (T similar to 20 keV). MMS can differentiate between the cold ion demagnetization region and hot ion demagnetization regions, which suggests that MMS was observing multiscale Hall physics. The observed Hall electric field is compared with a generalized Ohm's law, accounting for multiple ion populations. The cold ion population, despite its relatively high initial temperature, has a significant impact on the Hall electric field. These results show that multiscale Hall physics is relevant over a much larger temperature range than previously observed and is relevant for the whole magnetosphere as well as for other astrophysical plasma.

  • 26.
    Steinvall, K.
    et al.
    Swedish Inst Space Phys, Uppsala, Sweden.;Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden..
    Khotyaintsev, Yu. V.
    Swedish Inst Space Phys, Uppsala, Sweden..
    Graham, D. B.
    Swedish Inst Space Phys, Uppsala, Sweden..
    Vaivads, Andris
    Swedish Inst Space Phys, Uppsala, Sweden..
    Lindqvist, Per-Arne
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Russell, C. T.
    Univ Calif Los Angeles, Dept Earth Planetary & Space Sci, Los Angeles, CA USA..
    Burch, J. L.
    Southwest Res Inst, San Antonio, TX USA..
    Multispacecraft Analysis of Electron Holes2019In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 46, no 1, p. 55-63Article in journal (Refereed)
    Abstract [en]

    Electron holes (EHs) are nonlinear electrostatic structures in plasmas. Most previous in situ studies of EHs have been limited to single- and two-spacecraft methods. We present statistics of EHs observed by Magnetospheric Multiscale on the magnetospheric side of the magnetopause during October 2016 when the spacecraft separation was around 6km. Each EH is observed by all four spacecraft, allowing EH properties to be determined with unprecedented accuracy. We find that the parallel length scale, l(vertical bar), scales with the Debye length. The EHs can be separated into three groups of speed and potential based on their coupling to ions. We present a method for calculating the perpendicular length scale, l. The method can be applied to a small subset of the observed EHs for which we find shapes ranging from almost spherical to more oblate. For the remaining EHs we use statistical arguments to find l/l(vertical bar)approximate to 5, implying dominance of oblate EHs. Plain Language Summary Electron holes are positively charged structures moving along the magnetic field and are frequently observed in space plasmas in relation to strong currents and electron beams. Electron holes interact with the plasma, leading to electron heating and scattering. In order to understand the effect of these electron holes, we need to accurately determine their properties, such as velocity, length scale, and potential. Most earlier studies have relied on single- or two-spacecraft methods to analyze electron holes. In this study we use the four satellites of the Magnetospheric Multiscale mission to analyze 236 electron holes with unprecedented accuracy. We find that the holes can be divided into three distinct groups with different properties. Additionally, we calculate the width of individual electron holes, finding that they are typically much wider than long, resembling pancakes.

  • 27.
    Hajihoseini, Hamidreza
    et al.
    Univ Iceland, Sci Inst, Dunhaga 3, IS-107 Reykjavik, Iceland..
    Kateb, Movaffaq
    Univ Iceland, Sci Inst, Dunhaga 3, IS-107 Reykjavik, Iceland..
    Ingvarsson, Snorri Porgeir
    Univ Iceland, Sci Inst, Dunhaga 3, IS-107 Reykjavik, Iceland..
    Gudmundsson, Jon Tomas
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics. Univ Iceland, Sci Inst, Dunhaga 3, IS-107 Reykjavik, Iceland..
    Oblique angle deposition of nickel thin films by high-power impulse magnetron sputtering2019In: Beilstein Journal of Nanotechnology, ISSN 2190-4286, Vol. 10, p. 1914-1921Article in journal (Refereed)
    Abstract [en]

    Background: Oblique angle deposition is known for yielding the growth of columnar grains that are tilted in the direction of the deposition flux. Using this technique combined with high-power impulse magnetron sputtering (HiPIMS) can induce unique properties in ferromagnetic thin films. Earlier we have explored the properties of polycrystalline and epitaxially deposited permalloy thin films deposited under 35 degrees tilt using HiPIMS and compared it with films deposited by de magnetron sputtering (dcMS). The films prepared by HiPIMS present lower anisotropy and coercivity fields than films deposited with dcMS. For the epitaxial films dcMS deposition gives biaxial anisotropy while HiPIMS deposition gives a well-defined uniaxial anisotropy. Results: We report on the deposition of 50 nm polycrystalline nickel thin films by dcMS and HiPIMS while the tilt angle with respect to the substrate normal is varied from 0 degrees to 70 degrees. The HiPIMS-deposited films are always denser, with a smoother surface and are magnetically softer than the dcMS-deposited films under the same deposition conditions. The obliquely deposited HiPIMS films are significantly more uniform in terms of thickness. Cross-sectional SEM images reveal that the dcMS-deposited film under 70 degrees tilt angle consists of well-defined inclined nanocolumnar grains while grains of HiPIMS-deposited films are smaller and less tilted. Both deposition methods result in in-plane isotropic magnetic behavior at small tilt angles while larger tilt angles result in uniaxial magnetic anisotropy. The transition tilt angle varies with deposition method and is measured around 35 degrees for dcMS and 60 degrees for HiPIMS. Conclusion: Due to the high discharge current and high ionized flux fraction, the HiPIMS process can suppress the inclined columnar growth induced by oblique angle deposition. Thus, the ferromagnetic thin films obliquely deposited by HiPIMS deposition exhibit different magnetic properties than dcMS-deposited films. The results demonstrate the potential of the HiPIMS process to tailor the material properties for some important technological applications in addition to the ability to fill high aspect ratio trenches and coating on cutting tools with complex geometries.

  • 28.
    Zhou, M.
    et al.
    Nanchang Univ, Inst Space Sci & Technol, Nanchang, Jiangxi, Peoples R China..
    Deng, X. H.
    Nanchang Univ, Inst Space Sci & Technol, Nanchang, Jiangxi, Peoples R China..
    Zhong, Z. H.
    Nanchang Univ, Inst Space Sci & Technol, Nanchang, Jiangxi, Peoples R China..
    Pang, Y.
    Nanchang Univ, Inst Space Sci & Technol, Nanchang, Jiangxi, Peoples R China..
    Tang, R. X.
    Nanchang Univ, Inst Space Sci & Technol, Nanchang, Jiangxi, Peoples R China..
    El-Alaoui, M.
    UCLA, Dept Phys & Astron, Los Angeles, CA USA..
    Walker, R. J.
    UCLA, Dept Earth Planetary & Space Sci, Los Angeles, CA USA..
    Russell, C. T.
    UCLA, Dept Earth Planetary & Space Sci, Los Angeles, CA USA..
    Lapenta, G.
    Katholieke Univ Leuven, Dept Math, Ctr Plasma Astrophys, Leuven, Belgium..
    Strangeway, R. J.
    UCLA, Dept Earth Planetary & Space Sci, Los Angeles, CA USA..
    Torbert, R. B.
    Univ New Hampshire, Durham, NH 03824 USA..
    Burch, J. L.
    Southwest Res Inst, San Antonio, TX USA..
    Paterson, W. R.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Giles, B. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Khotyaintsev, Y. V.
    Swedish Inst Space Phys, Uppsala, Sweden..
    Ergun, R. E.
    Univ Colorado LASP, Boulder, CO USA..
    Lindqvist, Per-Arne
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Observations of an Electron Diffusion Region in Symmetric Reconnection with Weak Guide Field2019In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 870, no 1, article id 34Article in journal (Refereed)
    Abstract [en]

    The Magnetospheric Multiscale spacecraft encountered an electron diffusion region (EDR) in a symmetric reconnection in the Earth's magnetotail. The EDR contained a guide field of about 2 nT, which was 13% of the magnetic field in the inflow region, and its thickness was about 2 local electron inertial lengths. Intense energy dissipation, a super-Alfvenic electron jet, electron nongyrotropy, and crescent-shaped electron velocity distributions were observed in association with this EDR. These features are similar to those of the EDRs in asymmetric reconnection at the dayside magnetopause. Electrons gained about 50% of their energy from the immediate upstream to the EDR. Crescent electron distributions were seen at the boundary of the EDR, while highly curved magnetic field lines inside the EDR may have gyrotropized the electrons. The EDR was characterized by a parallel current that was carried by antiparallel drifting electrons that were probably accelerated by a parallel electric field along the guide field. These results reveal the essential electron physics of the EDR and provide a significant example of an EDR in symmetric reconnection with a weak guide field.

  • 29.
    De Spiegeleer, A.
    et al.
    Umea Univ, Dept Phys, Umea, Sweden..
    Hamrin, M.
    Umea Univ, Dept Phys, Umea, Sweden..
    Gunell, H.
    Umea Univ, Dept Phys, Umea, Sweden.;Belgian Inst Space Aeron, Brussels, Belgium..
    Volwerk, M.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Andersson, L.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA..
    Karlsson, Tomas
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Pitkanen, T.
    Umea Univ, Dept Phys, Umea, Sweden.;Shandong Univ, Inst Space Sci, Shandong Prov Key Lab Opt Astron & Solar Terr Env, Weihai, Peoples R China..
    Mouikis, C. G.
    Univ New Hampshire, Dept Phys, Durham, NH 03824 USA..
    Nilsson, H.
    Swedish Inst Space Sci, Kiruna, Sweden..
    Kistler, L. M.
    Univ New Hampshire, Dept Phys, Durham, NH 03824 USA..
    Oscillatory Flows in the Magnetotail Plasma Sheet: Cluster Observations of the Distribution Function2019In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 124, no 4, p. 2736-2754Article in journal (Refereed)
    Abstract [en]

    Plasma dynamics in Earth's magnetotail is often studied using moments of the distribution function, which results in losing information on the kinetic properties of the plasma. To better understand oscillatory flows observed in the midtail plasma sheet, we investigate two events, one in each hemisphere, in the transition region between the central plasma sheet and the lobes using the 2-D ion distribution function from the Cluster 4 spacecraft. In this case study, the oscillatory flows are a manifestation of repeated ion flux enhancements with pitch angle changing from 0 degrees to 180 degrees in the Northern Hemisphere and from 180 degrees to 0 degrees in the Southern Hemisphere. Similar pitch angle signatures are observed seven times in about 80 min for the Southern Hemisphere event and three times in about 80 min for the Northern Hemisphere event. The ion flux enhancements observed for both events are slightly shifted in time between different energy channels, indicating a possible time-of-flight effect from which we estimate that the source of particle is located similar to 5-25R(E) and similar to 40-107R(E) tailward of the spacecraft for the Southern and Northern Hemisphere event, respectively. Using a test particle simulation, we obtain similar to 21-46 R-E for the Southern Hemisphere event and tailward of X similar to - 65R(E) (outside the validity region of the model) for the Northern Hemisphere event. We discuss possible sources that could cause the enhancements of ion flux.

  • 30. Meyer, H.
    et al.
    Frassinetti, Lorenzo
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Garcia Carrasco, Alvaro
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Ratynskaia, Svetlana V.
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Rubel, Marek
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Thorén, Emil
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Tolias, Panagiotis
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Zohm, H.
    et al.,
    Overview of physics studies on ASDEX Upgrade2019In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 59, no 11, article id 112014Article in journal (Refereed)
    Abstract [en]

    The ASDEX Upgrade (AUG) programme, jointly run with the EUROfusion MST1 task force, continues to significantly enhance the physics base of ITER and DEMO. Here, the full tungsten wall is a key asset for extrapolating to future devices. The high overall heating power, flexible heating mix and comprehensive diagnostic set allows studies ranging from mimicking the scrape-off-layer and divertor conditions of ITER and DEMO at high density to fully non-inductive operation (q(95) = 5.5, beta(N) <= 2.8) at low density. Higher installed electron cyclotron resonance heating power <= 6 MW, new diagnostics and improved analysis techniques have further enhanced the capabilities of AUG. Stable high-density H-modes with P-sep/R <= 11 MW m(-1) with fully detached strike-points have been demonstrated. The ballooning instability close to the separatrix has been identified as a potential cause leading to the H-mode density limit and is also found to play an important role for the access to small edge-localized modes (ELMs). Density limit disruptions have been successfully avoided using a path-oriented approach to disruption handling and progress has been made in understanding the dissipation and avoidance of runaway electron beams. ELM suppression with resonant magnetic perturbations is now routinely achieved reaching transiently H-H98(y,H-2) <= 1.1. This gives new insight into the field penetration physics, in particular with respect to plasma flows. Modelling agrees well with plasma response measurements and a helically localised ballooning structure observed prior to the ELM is evidence for the changed edge stability due to the magnetic perturbations. The impact of 3D perturbations on heat load patterns and fast-ion losses have been further elaborated. Progress has also been made in understanding the ELM cycle itself. Here, new fast measurements of T-i and E-r allow for inter ELM transport analysis confirming that E-r is dominated by the diamagnetic term even for fast timescales. New analysis techniques allow detailed comparison of the ELM crash and are in good agreement with nonlinear MHD modelling. The observation of accelerated ions during the ELM crash can be seen as evidence for the reconnection during the ELM. As type-I ELMs (even mitigated) are likely not a viable operational regime in DEMO studies of 'natural' no ELM regimes have been extended. Stable I-modes up to n/n(GW) <= 0.7 have been characterised using beta-feedback. Core physics has been advanced by more detailed characterisation of the turbulence with new measurements such as the eddy tilt angle-measured for the first time-or the cross-phase angle of T-e and n(e) fluctuations. These new data put strong constraints on gyro-kinetic turbulence modelling. In addition, carefully executed studies in different main species (H, D and He) and with different heating mixes highlight the importance of the collisional energy exchange for interpreting energy confinement. A new regime with a hollow T-e profile now gives access to regimes mimicking aspects of burning plasma conditions and lead to nonlinear interactions of energetic particle modes despite the sub-Alfvenic beam energy. This will help to validate the fast-ion codes for predicting ITER and DEMO.

  • 31.
    Pucella, G.
    et al.
    ENEA, Fus & Nucl Safety Dept, CR Frascati, Via E Peuni 45, I-00044 Rome, Italy.
    Ratynskaia, Svetlana V.
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Tolias, Panagiotis
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Zito, P.
    ENEA, Fus & Nucl Safety Dept, CR Frascati, Via E Peuni 45, I-00044 Rome, Italy.
    et al.,
    Overview of the FTU results2019In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 59, no 11, article id 112015Article in journal (Refereed)
    Abstract [en]

    Since the 2016 IAEA Fusion Energy Conference, FTU operations have been mainly devoted to experiments on runaway electrons and investigations into a tin liquid limiter; other experiments have involved studies of elongated plasmas and dust. The tearing mode onset in the high density regime has been studied by means of the linear resistive code MARS, and the highly collisional regimes have been investigated. New diagnostics, such as a runaway electron imaging spectroscopy system for in-flight runaway studies and a triple Cherenkov probe for the measurement of escaping electrons, have been successfully installed and tested, and new capabilities of the collective Thomson scattering and the laser induced breakdown spectroscopy diagnostics have been explored.

  • 32. Joffrin, E.
    et al.
    Bergsåker, Henric
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Bykov, Igor
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Frassinetti, Lorenzo
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Fridström, Richard
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Garcia Carrasco, Alvaro
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Hellsten, Torbjörn
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Jonsson, Thomas
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Moon, Sunwoo
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Petersson, Per
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Rachlew, Elisabeth
    KTH, School of Engineering Sciences (SCI), Physics, Atomic and Molecular Physics.
    Ratynskaia, Svetlana V.
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Rubel, Marek
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Stefániková, Estera
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Ström, Petter
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Tholerus, Emmi
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Tolias, Panagiotis
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Vallejos, Pablo
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Weckmann, Armin
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Zhou, Yushan
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Zychor, I
    et al.,
    Overview of the JET preparation for deuterium-tritium operation with the ITER like-wall2019In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 59, no 11, article id 112021Article in journal (Refereed)
    Abstract [en]

    For the past several years, the JET scientific programme (Pamela et al 2007 Fusion Eng. Des. 82 590) has been engaged in a multi-campaign effort, including experiments in D, H and T, leading up to 2020 and the first experiments with 50%/50% D-T mixtures since 1997 and the first ever D-T plasmas with the ITER mix of plasma-facing component materials. For this purpose, a concerted physics and technology programme was launched with a view to prepare the D-T campaign (DTE2). This paper addresses the key elements developed by the JET programme directly contributing to the D-T preparation. This intense preparation includes the review of the physics basis for the D-T operational scenarios, including the fusion power predictions through first principle and integrated modelling, and the impact of isotopes in the operation and physics of D-T plasmas (thermal and particle transport, high confinement mode (H-mode) access, Be and W erosion, fuel recovery, etc). This effort also requires improving several aspects of plasma operation for DTE2, such as real time control schemes, heat load control, disruption avoidance and a mitigation system (including the installation of a new shattered pellet injector), novel ion cyclotron resonance heating schemes (such as the three-ions scheme), new diagnostics (neutron camera and spectrometer, active Alfven eigenmode antennas, neutral gauges, radiation hard imaging systems...) and the calibration of the JET neutron diagnostics at 14 MeV for accurate fusion power measurement. The active preparation of JET for the 2020 D-T campaign provides an incomparable source of information and a basis for the future D-T operation of ITER, and it is also foreseen that a large number of key physics issues will be addressed in support of burning plasmas.

  • 33.
    De Angeli, M.
    et al.
    CNR, Ist Sci & Tecnol Plasmi, Milan, Italy..
    Lazzaro, E.
    CNR, Ist Sci & Tecnol Plasmi, Milan, Italy..
    Tolias, Panagiotis
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Ratynskaia, Svetlana V.
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Vignitchouk, Ladislas
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Castaldo, C.
    ENEA, CR Frascati, I-00044 Rome, Italy..
    Apicella, M. L.
    ENEA, CR Frascati, I-00044 Rome, Italy..
    Gervasini, G.
    CNR, Ist Sci & Tecnol Plasmi, Milan, Italy..
    Giacomi, G.
    ENEA, CR Frascati, I-00044 Rome, Italy..
    Giovannozzi, E.
    ENEA, CR Frascati, I-00044 Rome, Italy..
    Granucci, G.
    CNR, Ist Sci & Tecnol Plasmi, Milan, Italy..
    Iafrati, M.
    ENEA, CR Frascati, I-00044 Rome, Italy..
    Iraji, D.
    Amirkabir Univ Technol, Energy Engn & Phys Dept, Tehran, Iran..
    Maddaluno, G.
    ENEA, CR Frascati, I-00044 Rome, Italy..
    Riva, G.
    CNR, Ist Chim Mat Condensata & Tecnol Energia, Via R Cozzi 53, I-20125 Milan, Italy..
    Uccello, A.
    CNR, Ist Sci & Tecnol Plasmi, Milan, Italy..
    Pre-plasma remobilization of ferromagnetic dust in FTU and possible interference with tokamak operations2019In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 59, no 10, article id 106033Article in journal (Refereed)
    Abstract [en]

    Experimental evidence of the pre-plasma remobilization of ferromagnetic dust in FTU is presented. Thomson scattering data and IR camera observations document the occurrence of intrinsic dust remobilization prior to discharge start-up and allow for a rough calculation of the average mobilized dust density. Exposures of calibrated extrinsic non-magnetic and ferromagnetic dust to sole magnetic field discharges reveal that the magnetic moment force is the main mobilizing force, as confirmed by theoretical estimates. Pre-plasma remobilization probabilities are computed for varying dust sizes. The impact of prematurely remobilized dust on the breakdown and burn-through start-up phases is investigated together with the discharge termination induced once the plasma plateau is established.

  • 34.
    Breuillard, H.
    et al.
    Univ Orleans, CNES, CNRS, UMR7328,LPC2E, Orleans, France.;Univ Paris Sud, Sorbonne Univ, Ecole Polytech, UMR7648 CNRS,Lab Phys Plasmas, Paris, France..
    Henri, P.
    Univ Orleans, CNES, CNRS, UMR7328,LPC2E, Orleans, France..
    Bucciantini, L.
    Univ Orleans, CNES, CNRS, UMR7328,LPC2E, Orleans, France..
    Volwerk, M.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Karlsson, Tomas
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Eriksson, A.
    Swedish Inst Space Phys, Uppsala, Sweden..
    Johansson, F.
    Swedish Inst Space Phys, Uppsala, Sweden..
    Odelstad, E.
    Swedish Inst Space Phys, Uppsala, Sweden..
    Richter, I
    Tech Univ Carolo Wilhelmina Braunschweig, Braunschweig, Germany..
    Goetz, C.
    Tech Univ Carolo Wilhelmina Braunschweig, Braunschweig, Germany..
    Vallieres, X.
    Univ Orleans, CNES, CNRS, UMR7328,LPC2E, Orleans, France..
    Hajra, R.
    Univ Orleans, CNES, CNRS, UMR7328,LPC2E, Orleans, France.;Natl Atmospher Res Lab, Tirupati, Andhra Pradesh, India..
    Properties of the singing comet waves in the 67P/Churyumov-Gerasimenko plasma environment as observed by the Rosetta mission2019In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 630, article id A39Article in journal (Refereed)
    Abstract [en]

    Using in situ measurements from different instruments on board the Rosetta spacecraft, we investigate the properties of the newly discovered low-frequency oscillations, known as singing comet waves, that sometimes dominate the close plasma environment of comet 67P/Churyumov-Gerasimenko. These waves are thought to be generated by a modified ion-Weibel instability that grows due to a beam of water ions created by water molecules that outgass from the comet. We take advantage of a cometary outburst event that occurred on 2016 February 19 to probe this generation mechanism. We analyze the 3D magnetic field waveforms to infer the properties of the magnetic oscillations of the cometary ion waves. They are observed in the typical frequency range (similar to 50 mHz) before the cometary outburst, but at similar to 20 mHz during the outburst. They are also observed to be elliptically right-hand polarized and to propagate rather closely (similar to 0-50 degrees) to the background magnetic field. We also construct a density dataset with a high enough time resolution that allows us to study the plasma contribution to the ion cometary waves. The correlation between plasma and magnetic field variations associated with the waves indicates that they are mostly in phase before and during the outburst, which means that they are compressional waves. We therefore show that the measurements from multiple instruments are consistent with the modified ion-Weibel instability as the source of the singing comet wave activity. We also argue that the observed frequency of the singing comet waves could be a way to indirectly probe the strength of neutral plasma coupling in the 67P environment.

  • 35.
    Stawarz, J. E.
    et al.
    Imperial Coll London, Dept Phys, London, England..
    Eastwood, J. P.
    Imperial Coll London, Dept Phys, London, England..
    Phan, T. D.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA..
    Gingell, I. L.
    Imperial Coll London, Dept Phys, London, England..
    Shay, M. A.
    Univ Delaware, Dept Phys & Astron, Newark, DE 19716 USA..
    Burch, J. L.
    Southwest Res Inst, San Antonio, TX USA..
    Ergun, R. E.
    Univ Colorado, Dept Astrophys & Planetary Sci, Boulder, CO 80309 USA.;Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA..
    Giles, B. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Gershman, D. J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Le Contel, O.
    Univ Paris Sud, Lab Phys Plasmas, CNRS, Ecole Polytech,Sorbonne Univ,Observ Paris, Paris, France..
    Lindqvist, Per-Arne
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Russell, C. T.
    Univ Calif Los Angeles, Dept Earth Planetary & Space Sci, Los Angeles, CA USA..
    Strangeway, R. J.
    Univ Calif Los Angeles, Dept Earth Planetary & Space Sci, Los Angeles, CA USA..
    Torbert, R. B.
    Univ New Hampshire, Dept Phys, Durham, NH 03824 USA..
    Argall, M. R.
    Univ New Hampshire, Dept Phys, Durham, NH 03824 USA..
    Fischer, D.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Magnes, W.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Franci, L.
    Queen Mary Univ London, Sch Phys & Astron, London, England..
    Properties of the Turbulence Associated with Electron-only Magnetic Reconnection in Earth's Magnetosheath2019In: Astrophysical Journal Letters, ISSN 2041-8205, E-ISSN 2041-8213, Vol. 877, no 2, article id L37Article in journal (Refereed)
    Abstract [en]

    Turbulent plasmas generate intense current structures, which have long been suggested as magnetic reconnection sites. Recent Magnetospheric Multiscale observations in Earth's magnetosheath revealed a novel form of reconnection where the dynamics only couple to electrons, without ion involvement. It was suggested that such dynamics were driven by magnetosheath turbulence. In this study, the fluctuations are examined to determine the properties of the turbulence and if a signature of reconnection is present in the turbulence statistics. The study reveals statistical properties consistent with plasma turbulence with a correlation length of similar to 10 ion inertial lengths. When reconnection is more prevalent, a steepening of the magnetic spectrum occurs at the length scale of the reconnecting current sheets. The statistics of intense currents suggest the prevalence of electron-scale current sheets favorable for electron reconnection. The results support the hypothesis that electron reconnection is driven by turbulence and highlight diagnostics that may provide insight into reconnection in other turbulent plasmas.

  • 36.
    Oieroset, M.
    et al.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA. rake, J. F..
    Phan, T. D.
    Drake, J. F.
    Eastwood, J. P.
    Fuselier, S. A.
    Strangeway, R. J.
    Haggerty, C.
    Shay, M. A.
    Oka, M.
    Wang, S.
    Chen, L-J
    Kacem, I
    Lavraud, B.
    Angelopoulos, V
    Burch, J. L.
    Torbert, R. B.
    Ergun, R. E.
    Khotyaintsev, Y.
    Lindqvist, Per-Arne
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Gershman, D. J.
    Giles, B. L.
    Pollock, C.
    Moore, T. E.
    Russell, C. T.
    Saito, Y.
    Avanov, L. A.
    Paterson, W.
    Reconnection With Magnetic Flux Pileup at the Interface of Converging ts at the Magnetopause2019In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 46, no 4, p. 1937-1946Article in journal (Refereed)
    Abstract [en]

    We report Magnetospheric Multiscale observations of reconnection in a in current sheet at the interface of interlinked flux tubes carried by nverging reconnection jets at Earth's magnetopause. The ion skin pth-scale width of the interface current sheet and the non-frozen-in ns indicate that Magnetospheric Multiscale crossed the reconnection yer near the X-line, through the ion diffusion region. Significant leup of the reconnecting component of the magnetic field in this and ree other events on approach to the interface current sheet was companied by an increase in magnetic shear and decrease in , leading conditions favorable for reconnection at the interface current sheet. e pileup also led to enhanced available magnetic energy per particle d strong electron heating. The observations shed light on the olution and energy release in 3-D systems with multiple reconnection tes. ain Language Summary The Earth and the solar wind magnetic fields terconnect through a process called magnetic reconnection. The newly connected magnetic field lines are strongly bent and accelerate rticles, similar to a rubber band in a slingshot. In this paper we ve used observations from NASA's Magnetospheric MultiScale spacecraft investigate what happens when two of these slingshot-like magnetic eld lines move toward each other and get tangled up. We found that the o bent magnetic field lines tend to orient themselves perpendicular to ch other as they become interlinked and stretched, similar to what bber bands would do. This reorientation allows the interlinked gnetic fields to reconnect again, releasing part of the built-up gnetic energy as strong electron heating. The results are important cause they show how interlinked magnetic fields, which occur in many lar and astrophysics contexts, reconnect and produce enhanced electron ating, something that was not understood before.

  • 37.
    Kateb, Movaffaq
    et al.
    Univ Iceland, Sci Inst, Dunhaga 3, IS-107 Reykjavik, Iceland..
    Hajihoseini, Hamidreza
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics. Univ Iceland, Sci Inst, Dunhaga 3, IS-107 Reykjavik, Iceland.
    Gudmundsson, Jon Tomas
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics. Univ Iceland, Sci Inst, Dunhaga 3, IS-107 Reykjavik, Iceland.
    Ingvarsson, Snorri
    Univ Iceland, Sci Inst, Dunhaga 3, IS-107 Reykjavik, Iceland..
    Role of ionization fraction on the surface roughness, density, and interface mixing of the films deposited by thermal evaporation, dc magnetron sputtering, and HiPIMS: An atomistic simulation2019In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 37, no 3, article id 031306Article in journal (Refereed)
    Abstract [en]

    The effect of ionization fraction on the epitaxial growth of Cu film on Cu (111) substrate at room temperature is explored. Three deposition methods, thermal evaporation, dc magnetron sputtering (dcMS), and high power impulse magnetron sputtering (HiPIMS) are compared. Three deposition conditions, i.e., fully neutral, 50% ionized, and 100% ionized flux were considered thermal evaporation, dcMS, and HiPIMS, respectively, for similar to 20 000 adatoms. It is shown that higher ionization fraction of the deposition flux leads to smoother surfaces by two major mechanisms, i.e., decreasing clustering in the vapor phase and bicollision of high energy ions at the film surface. The bicollision event consists of local amorphization which fills the gaps between islands followed by crystallization due to secondary collisions. The bicollision events are found to be very important to prevent island growth to become dominant and increase the surface roughness. Regardless of the deposition method, epitaxial Cu thin films suffer from stacking fault areas (twin boundaries) in agreement with recent experimental results. Thermal evaporation and dcMS deposition present negligible interface mixing while HiPIMS deposition presents considerable interface mixing. Published by the AVS.

  • 38.
    Garzotti, L.
    et al.
    Culham Sci Ctr, CCFE, Abingdon OX14 3DB, Oxon, England.;CCFE Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England..
    Frassinetti, Lorenzo
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Stefániková, Estera
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Bergsåker, Henric
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Bykov, Igor
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Garcia Carrasco, Alvaro
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Hellsten, Torbjörn
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Jonsson, Thomas
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Menmuir, Sheena
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics. CCFE Culham Sci Ctr, Abingdon OX14 3DB, Oxon, England..
    Petersson, Per
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Rachlew, Elisabeth
    KTH, School of Engineering Sciences (SCI), Physics, Atomic and Molecular Physics.
    Ratynskaia, Svetlana V.
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Rubel, Marek
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Ström, Petter
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Tholerus, Emmi
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Tolias, Panagiotis
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Vallejos, Pablo
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Weckmann, Armin
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Zhou, Yushan
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Zychor, I.
    Natl Ctr Nucl Res, PL-05400 Otwock, Poland..
    Scenario development for D-T operation at JET2019In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 59, no 7, article id 076037Article in journal (Refereed)
    Abstract [en]

    The JET exploitation plan foresees D-T operations in 2020 (DTE2). With respect to the first D-T campaign in 1997 (DTE1), when JET was equipped with a carbon wall, the experiments will be conducted in presence of a beryllium-tungsten ITER-like wall and will benefit from an extended and improved set of diagnostics and higher additional heating power (32 MW neutral beam injection + 8 MW ion cyclotron resonance heating). There are several challenges presented by operations with the new wall: a general deterioration of the pedestal confinement; the risk of heavy impurity accumulation in the core, which, if not controlled, can cause the radiative collapse of the discharge; the requirement to protect the divertor from excessive heat loads, which may damage it permanently. Therefore, an intense activity of scenario development has been undertaken at JET during the last three years to overcome these difficulties and prepare the plasmas needed to demonstrate stationary high fusion performance and clear alpha particle effects. The paper describes the status and main achievements of this scenario development activity, both from an operational and plasma physics point of view.

  • 39. Rousselot, P.
    et al.
    Opitom, C.
    Jehin, E.
    Hutsemékers, D.
    Manfroid, J.
    Villarreal, M. N.
    Li, J. -Y
    Castillo-Rogez, J.
    Russell, C. T.
    Vernazza, P.
    Marsset, M.
    Roth, Lorenz
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Dumas, C.
    Yang, B.
    Prettyman, T. H.
    Mousis, O.
    Search for water outgassing of (1) Ceres near perihelion2019In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 628, article id A22Article in journal (Refereed)
    Abstract [en]

    Context. (1) Ceres is the largest body in the main asteroid belt and one of the most intriguing objects in the solar system, in part because of the discovery of water outgassing by the Herschel Space Observatory (HSO) and its still-debated origin. Ceres was the target of NASA's Dawn spacecraft for 3.5 yr, which achieved a detailed characterization of the dwarf planet. The possible influence of the local flux of solar energetic particles (SEP) on the production of a Cerean exosphere and water vapor has been suggested, in addition to the sublimation of water ice that depends on the temperature, meaning the heliocentric distance. Aims. We used the opportunity of both the perihelion passage of (1) Ceres in April 2018, and the presence of Dawn in its vicinity (for measuring the SEP flux in real time) to check the influence of heliocentric distance and SEP flux on water outgassing. Methods. We searched for OH emission lines near the limb of Ceres in the near-UV with the UVES spectrograph mounted on the 8-m ESO Very Large Telescope. Two spectra were recorded when Ceres was close to its perihelion, in February 2018, and with Dawn spacecraft orbiting Ceres. It was possible to simultaneously measure energetic particles around Ceres at the time of our observations. Results. Our observations did not permit detection of OH emission lines to a very high sensitivity level. This level is estimated to correspond to a global water production rate of QH2O ∼ 2 × 1026 molecules s-1, similar to the water production rate derived from HSO observations. The solar energetic particles flux measured around Ceres was negligible at the time of these observations. Conclusions. Our observations support the idea that heliocentric distance (i.e., the sublimation of water ice) does not play a major role in the water emission from Ceres. This production rate could be either related to SEP events or to other mechanisms, possibly of endogenic origin.

  • 40.
    Nakamura, Rumi
    et al.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Genestreti, Kevin J.
    Austrian Acad Sci, Space Res Inst, Graz, Austria.;Univ New Hampshire, Space Sci Ctr, Durham, NH 03824 USA..
    Naltamora, Takuma
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Baumjohann, Wolfgang
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Varsani, Ali
    Univ Coll London, Mullard Space Sci Lab, Dorking, Surrey, England..
    Nagai, Tsugunobu
    Japan Aerosp Explorat Agcy, Inst Space & Astronaut Sci, Sagamihara, Kanagawa, Japan..
    Bessho, Naoki
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Burch, James L.
    Southwest Res Inst, San Antonio, TX USA..
    Denton, Richard E.
    Dartmouth Coll, Dept Phys & Astron, Hanover, NH 03755 USA..
    Eastwood, Jonathan P.
    Imperial Coll London, Blackett Lab, London, England..
    Ergun, Robert E.
    Univ Colorado, Dept Astrophys & Planetary Sci, Boulder, CO USA..
    Gershman, Daniel J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Giles, Arbara L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Hasegaw, Iroshi
    Japan Aerosp Explorat Agcy, Inst Space & Astronaut Sci, Sagamihara, Kanagawa, Japan..
    Hesse, Michael
    Univ Bergen, Dept Phys & Technol, Bergen, Norway..
    Lindqvist, Per-Arne
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Russell, Hristopher T.
    Univ Calif Los Angeles, Dept Earth Planetary & Space Sci, Los Angeles, CA USA..
    Stawarz, Ulia E.
    Imperial Coll London, Blackett Lab, London, England..
    Strangeway, Robert J.
    Univ Calif Los Angeles, Dept Earth Planetary & Space Sci, Los Angeles, CA USA..
    Torber, Roy B.
    Univ New Hampshire, Space Sci Ctr, Durham, NH 03824 USA.;Southwest Res Inst, San Antonio, TX USA..
    Structure of the Current Sheet in the 11 July 2017 Electron Diffusion Region Event2019In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 124, no 2, p. 1173-1186Article in journal (Refereed)
    Abstract [en]

    The structure of the current sheet along the Magnetospheric Multiscale (MMS) orbit is examined during the 11 July 2017 Electron Diffusion Region (EDR) event. The location of MMS relative to the X-line is deduced and used to obtain the spatial changes in the electron parameters. The electron velocity gradient values are used to estimate the reconnection electric field sustained by nongyrotropic pressure. It is shown that the observations are consistent with theoretical expectations for an inner EDR in 2-D reconnection. That is, the magnetic field gradient scale, where the electric field due to electron nongyrotropic pressure dominates, is comparable to the gyroscale of the thermal electrons at the edge of the inner EDR. Our approximation of the MMS observations using a steady state, quasi-2-D, tailward retreating X-line was valid only for about 1.4 s. This suggests that the inner EDR is localized; that is, electron outflow jet braking takes place within an ion inertia scale from the X-line. The existence of multiple events or current sheet processes outside the EDR may play an important role in the geometry of reconnection in the near-Earth magnetotail. Plain Language Summary Magnetic reconnection is the process by which magnetic field lines coming from one region are broken and reconnected with magnetic field lines coming from another region. The simplest descriptions of magnetic reconnection are two dimensional, and a number of theoretical predictions have been made using the two-dimensional assumption. We study a magnetic reconnection event observed by the Magnetospheric Multiscale spacecraft on 11 July 2017 and find approximate agreement between the observations and the predictions of a two-dimensional model. The agreement includes the scale size of the reconnection region, details of the particle orbits, and the rate of reconnection.

  • 41. Sergeev, V. A.
    et al.
    Apatenkov, S. V.
    Nakamura, R.
    Baumjohann, W.
    Khotyaintsev, Y. V.
    Kauristie, K.
    van de Kamp, M.
    Burch, J. L.
    Ergun, R. E.
    Lindqvist, Per-Arne
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Torbert, R.
    Russell, C. T.
    Giles, B. L.
    Substorm-Related Near-Earth Reconnection Surge: Combining Telescopic and Microscopic Views2019In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 46, no 12, p. 6239-6247Article in journal (Refereed)
    Abstract [en]

    A strong ~11-min-long surge of the lobe reconnection was observed during a substorm on the tailward side of the near-Earth neutral line. In the southern lobe near the reconnection separatrix the MMS spacecraft observed short-duration earthward electron beams providing the local Hall current, tailward propagating Alfven wave (AW) bursts with Poynting flux up to 10−4 W/m2, and large-amplitude E field spikes (e-holes) and low hybrid waves. The reconnection surge was accompanied by substorm current wedge formation and fast poleward expansion of auroral bulge-related westward electrojet in the conjugate ionosphere. During its meridional crossing above the expanding bulge the Metop-2 spacecraft observed an intense energetic precipitation spike near the expected X line foot point and confirmed the dipolarized character of magnetic field lines inside of the bulge. Globally the observed average reconnection rate (&lt;Ey &gt; ~3.3 mV/m) was sufficient to produce the magnetic flux increase in the bulge, associated with observed fast poleward expansion (about 6° latitude in 5 min).

  • 42.
    Tolias, Panagiotis
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    De Angeli, M.
    CNR, Ist Fis Plasma, Via Corsi 53, I-20125 Milan, Italy..
    Riva, G.
    CNR, Inst Condensed Matter Chem & Energy Technol, Via Cozzi 53, I-20125 Milan, Italy..
    Ratynskaia, Svetlana V.
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Daminelli, G.
    CNR, Inst Condensed Matter Chem & Energy Technol, Via Cozzi 53, I-20125 Milan, Italy..
    Laguardia, L.
    CNR, Ist Fis Plasma, Via Corsi 53, I-20125 Milan, Italy..
    Pedron, M.
    CNR, Ist Fis Plasma, Via Corsi 53, I-20125 Milan, Italy..
    Ripamonti, D.
    CNR, Inst Condensed Matter Chem & Energy Technol, Via Cozzi 53, I-20125 Milan, Italy..
    Uccello, A.
    CNR, Ist Fis Plasma, Via Corsi 53, I-20125 Milan, Italy..
    Vassallo, E.
    CNR, Ist Fis Plasma, Via Corsi 53, I-20125 Milan, Italy..
    The adhesion of tungsten dust on plasma-exposed tungsten surfaces2019In: Nuclear Materials and Energy, E-ISSN 2352-1791, Vol. 18, p. 18-22Article in journal (Refereed)
    Abstract [en]

    The adhesion of tungsten dust is measured on plasma-exposed and non-exposed tungsten substrates with the electrostatic detachment method. Tungsten substrates of comparable surface roughness have been exposed to the deuterium plasmas of the GyM linear device and the argon plasmas of rf glow discharges under conditions which invariably modify the surface composition due to physical sputtering. The adhesion has been systematically characterized for different spherical nearly monodisperse dust populations. Independent of the dust size, an approximate 50% post-exposure reduction of the average and spread of the adhesive force has been consistently observed and attributed to surface chemistry modifications.

  • 43.
    Kullen, Anita
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Space and Plasma Physics.
    Thor, Simon
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Space and Plasma Physics.
    Karlsson, Tomas
    KTH, School of Electrical Engineering and Computer Science (EECS), Electrical Engineering, Space and Plasma Physics.
    The Difference Between Isolated Flux Transfer Events and Flux Transfer Event Cascades2019In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402Article in journal (Refereed)
    Abstract [en]

    This flux transfer event (FTE) study is based on 984 FTEs originally identified by Wang et al. (2005, ) in Cluster data. Due to Cluster's orbit, the FTE list exclusively contains events detected at the high-latitude dayside magnetopause and low-latitude flanks. The focus of this study is on FTE separation time. The results show that FTEs appearing in cascades are mainly located at the northern dusk and southern dawn magnetopause, while isolated FTEs are equally spread over the region covered by Cluster. This difference may be explained by the different interplanetary magnetic field (IMF) conditions during which the subsets occur. For isolated FTEs, average IMF B-y is close to zero. During such conditions, FTEs are expected to form at arbitrary longitudes along an equatorial merging line. After formation, they propagate northward and southward, causing an equal distribution at higher latitudes. In contrast, FTE cascades typically occur during weakly southward IMF with a negative B-y component. Their asymmetric distribution at higher latitudes is consistent with both the component and the antiparallel merging model for nonzero B-y. In both scenarios, newly formed FTEs are expected to move to the northern dusk and southern dawn regions, as observed. Many FTE cascades appearing during northward IMF are located close to the low-latitude flanks, confirming previous reports. We discovered that such FTEs appear during large IMF values. Another new result is that 16% of all isolated FTEs appear during small IMF cone angles, suggesting that these may form as a result of magnetosheath jets impacting on the magnetopause.

  • 44.
    Grigore, E.
    et al.
    Euratom MEdC Assoc, Natl Inst Laser Plasma & Radiat Phys, Bucharest, Romania..
    Gherendi, M.
    Euratom MEdC Assoc, Natl Inst Laser Plasma & Radiat Phys, Bucharest, Romania..
    Baiasu, F.
    Euratom MEdC Assoc, Natl Inst Laser Plasma & Radiat Phys, Bucharest, Romania..
    Firdaouss, M.
    IRFM CEA Cadarache, F-13108 St Paul Les Durance, France..
    Hernandez, C.
    IRFM CEA Cadarache, F-13108 St Paul Les Durance, France..
    Weckmann, Armin
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics. KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Petersson, Per
    KTH, School of Electrical Engineering and Computer Science (EECS), Fusion Plasma Physics.
    Hakola, A.
    VTT Tech Res Ctr Finland Ltd, POB 1000, FI-02044 Espoo, Finland..
    The influence of N on the D retention within W coatings for fusion applications2019In: Fusion engineering and design, ISSN 0920-3796, E-ISSN 1873-7196, Vol. 146, p. 1959-1962Article in journal (Refereed)
    Abstract [en]

    Plasma facing components (PFC) in a fusion device are subjected to a harsh operating environment involving high heat fluxes and exposure to high fluxes of hydrogen isotopes. This exposure can lead to high fuel retention that can raise serious concern from the safety point of view. One of the reasons for the use of W as a material for the construction of the first wall is to reduce fuel retention compared to carbon wall. Nitrogen seeding, used during the operation of fusion reactors, represents a method to cool the divertor plasma and to reduce the W source in the divertor due to ELMS. However an exposure of the PFC to a combination of hydrogen isotopes and nitrogen can lead to changes in properties of exposed surfaces or to unexpected material behavior. In this work, the influence of nitrogen on the deuterium content within tungsten coatings produced by reactive high power impulse magnetron sputtering (HIPIMS) was investigated. The deposition process of W coatings in a nitrogen deuterium environment leads to a significant retention of deuterium. Coatings with a deuterium content up to 54 at% were obtained in the presence of nitrogen compared with a deuterium content of 25 at% measured for the coatings produced in absence of nitrogen from the deposition atmosphere.

  • 45.
    Liu, Z-Y
    et al.
    Peking Univ, Inst Space Phys & Appl Technol, Beijing, Peoples R China..
    Zong, Q-G
    Peking Univ, Inst Space Phys & Appl Technol, Beijing, Peoples R China..
    Zhou, X-Z
    Peking Univ, Inst Space Phys & Appl Technol, Beijing, Peoples R China..
    Hao, Y. X.
    Peking Univ, Inst Space Phys & Appl Technol, Beijing, Peoples R China..
    Yau, A. W.
    Univ Calgary, Dept Phys & Astron, Calgary, AB, Canada..
    Zhang, H.
    Univ Alaska, Geophys Inst, Fairbanks, AK 99701 USA..
    Chen, X-R
    Peking Univ, Inst Space Phys & Appl Technol, Beijing, Peoples R China..
    Fu, S. Y.
    Peking Univ, Inst Space Phys & Appl Technol, Beijing, Peoples R China..
    Pollock, C. J.
    Denali Sci, Fairbanks, AK USA..
    Le, G.
    NASA, Goddard Space Flight Ctr, Heliophys Sci Div, Greenbelt, MD USA..
    Ergun, R. E.
    Univ Colorado, Dept Astrophys & Planetary Sci, Boulder, CO 80309 USA..
    Lindqvist, Per-Arne
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    ULF Waves Modulating and Acting as Mass Spectrometer for Dayside Ionospheric Outflow Ions2019In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 46, no 15, p. 8633-8642Article in journal (Refereed)
    Abstract [en]

    Ionospheric outflow has been shown to be a dominant ion source of Earth's magnetosphere. However, most studies in the literature are about ionospheric outflow injected into the nightside magnetosphere. We still know little about ionospheric outflow injected into the dayside magnetosphere and its further energization after it enters the magnetosphere. Here, with data from Magnetospheric Multiscale mission, we report direct observations of the modulation of dayside ionospheric outflow ions by ultralow frequency (ULF) waves. The observations indicate that the modulation is mass dependent, which demonstrates the possibility of using ULF waves as a mass spectrometer to identify ion species. Moreover, the measurement suggests that polarization drift may play a role in O+ modulation, which may lead to a true acceleration and even nonadiabatic behavior of O+. This interaction scenario can work throughout the whole magnetosphere and impact upon the plasma environment and dynamics.

  • 46.
    Yao, S. T.
    et al.
    Shandong Univ, Inst Space Sci, Shandong Prov Key Lab Opt Astron & Solar Terr Env, Weihai, Peoples R China.;Chinese Acad Sci, Natl Space Sci Ctr, State Key Lab Space Weather, Beijing, Peoples R China..
    Shi, Q. Q.
    Shandong Univ, Inst Space Sci, Shandong Prov Key Lab Opt Astron & Solar Terr Env, Weihai, Peoples R China..
    Yao, Z. H.
    UCL, Mullard Space Sci Lab, London, England.;Univ Liege, STAR Inst, Lab Phys Atmospher & Planetaire, Liege, Belgium..
    Li, J. X.
    Univ Calif Los Angeles, Dept Atmospher & Ocean Sci, Los Angeles, CA USA..
    Yue, C.
    Univ Calif Los Angeles, Dept Atmospher & Ocean Sci, Los Angeles, CA USA..
    Tao, X.
    Univ Sci & Technol China, Dept Geophys & Planetary Sci, CAS Key Lab Geospace Environm, Hefei, Anhui, Peoples R China..
    Degeling, A. W.
    Shandong Univ, Inst Space Sci, Shandong Prov Key Lab Opt Astron & Solar Terr Env, Weihai, Peoples R China..
    Zong, Q. G.
    Peking Univ, Sch Earth & Space Sci, Beijing, Peoples R China..
    Wang, X. G.
    Harbin Inst Technol, Dept Phys, Harbin, Heilongjiang, Peoples R China..
    Tian, A. M.
    Shandong Univ, Inst Space Sci, Shandong Prov Key Lab Opt Astron & Solar Terr Env, Weihai, Peoples R China..
    Russell, C. T.
    Univ Calif Los Angeles, Dept Earth Planetary & Space Sci, Los Angeles, CA USA..
    Zhou, X. Z.
    Peking Univ, Sch Earth & Space Sci, Beijing, Peoples R China..
    Guo, R. L.
    Chinese Acad Sci, Inst Geol & Geophys, Key Lab Earth & Planetary Phys, Beijing, Peoples R China..
    Rae, I. J.
    UCL, Mullard Space Sci Lab, London, England..
    Fu, H. S.
    Beihang Univ, Sch Space & Environm, Beijing, Peoples R China..
    Zhang, H.
    Univ Alaska Fairbanks, Phys Dept, Fairbanks, AK USA.;Univ Alaska Fairbanks, Geophys Inst, Fairbanks, AK 99775 USA..
    Li, L.
    Harbin Inst Technol, Dept Phys, Harbin, Heilongjiang, Peoples R China..
    Le Contel, O.
    Univ Paris Sud, Sorbonne Univ, Lab Phys Plasmas, Observ Paris,Ecole Polytech,CNRS,UMR7648, Paris, France..
    Torbert, R. B.
    Univ New Hampshire, Dept Phys, Durham, NH 03824 USA..
    Ergun, R. E.
    Univ Colorado, Dept Astrophys & Planetary Sci, Boulder, CO 80309 USA..
    Lindqvist, Per-Arne
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Pollock, C. J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Giles, B. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Waves in Kinetic-Scale Magnetic Dips: MMS Observations in the Magnetosheath2019In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 46, no 2, p. 523-533Article in journal (Refereed)
    Abstract [en]

    Kinetic scale magnetic dips (KSMDs), with a significant depression in magnetic field strength, and scale length close to and less than one proton gyroradius, were reported in the turbulent plasmas both in recent observation and numerical simulation studies. These KSMDs likely play important roles in energy conversion and dissipation. In this study, we present observations of the KSMDs that are labeled whistler mode waves, electrostatic solitary waves, and electron cyclotron waves in the magnetosheath. The observations suggest that electron temperature anisotropy or beams within KSMD structures provide free energy to generate these waves. In addition, the occurrence rates of the waves are higher in the center of the magnetic dips than at their edges, implying that the KSMDs might be the origin of various kinds of waves. We suggest that the KSMDs could provide favorable conditions for the generation of waves and transfer energy to the waves in turbulent magnetosheath plasmas. Plain Language Summary The Earth's magnetosheath is a turbulent plasma environment where energy conversion, particle acceleration, and mass and momentum transport take place. Many of these key processes involve kinetic-scale physics. However, in-depth studies from previous missions are limited by their lower spacecraft data resolution. The recent Magnetospheric Multiscale (MMS) mission provides us with a large amount of high-temporal cadence data for studying kinetic-scale physics in the magnetosheath. In this study, we report whistler mode waves, electrostatic solitary waves and electron cyclotron waves within kinetic-scale magnetic dips (KSMDs) that can be generated in the turbulent magnetosheath. These waves could be excited by electron temperature anisotropy or beams. As is well known, plasma waves are important processes in converting energy, accelerating and scattering electrons and ions, and modifying the distributions of charged particles. If plasma instabilities develop within the KSMDs, the resulting waves could absorb free energy from plasma particles and may propagate out of the KSMDs. Thus, our discoveries could significantly advance the understanding of energy conversion and dissipation for kinetic-scale turbulence. This study provides a new reference not only for observations in space physics but also for related basic plasma theories and numerical simulations.

  • 47.
    Ren, Y.
    et al.
    Chinese Acad Sci, Natl Space Sci Ctr, State Key Lab Space Weather, Beijing, Peoples R China..
    Dai, L.
    Chinese Acad Sci, Natl Space Sci Ctr, State Key Lab Space Weather, Beijing, Peoples R China..
    Li, W.
    Boston Univ, Ctr Space Phys, Boston, MA 02215 USA..
    Tao, X.
    Univ Sci & Technol China, Dept Geophys & Planetary Sci, CAS Key Lab Geospace Environm, Hefei, Anhui, Peoples R China..
    Wang, C.
    Chinese Acad Sci, Natl Space Sci Ctr, State Key Lab Space Weather, Beijing, Peoples R China..
    Tang, B.
    Chinese Acad Sci, Natl Space Sci Ctr, State Key Lab Space Weather, Beijing, Peoples R China..
    Lavraud, B.
    Univ Toulouse, Inst Rech Astrophys & Planetol, CNRS, UPS,CNES, Toulouse, France..
    Wu, Y.
    Univ Sci & Technol China, Dept Geophys & Planetary Sci, CAS Key Lab Geospace Environm, Hefei, Anhui, Peoples R China..
    Burch, J. L.
    Southwest Res Inst, San Antonio, TX USA..
    Giles, B. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Le Contel, O.
    Univ Paris Sud, Sorbonne Univ, Observ Paris, Lab Phys Plasmas,CNRS,Ecole Polytech, Paris, France..
    Torbert, R. B.
    Univ New Hampshire, Dept Phys, Durham, NH 03824 USA..
    Russell, C. T.
    Univ Calif Los Angeles, Earth & Planetary Sci, Los Angeles, CA USA..
    Strangeway, R. J.
    Univ Calif Los Angeles, Earth & Planetary Sci, Los Angeles, CA USA..
    Ergun, R. E.
    Chinese Acad Sci, Natl Space Sci Ctr, State Key Lab Space Weather, Beijing, Peoples R China.;Univ Colorado, Dept Astrophys & Planetary Sci, Boulder, CO 80309 USA..
    Lindqvist, Per-Arne
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics. Chinese Acad Sci, Natl Space Sci Ctr, State Key Lab Space Weather, Beijing, Peoples R China..
    Whistler Waves Driven by Field-Aligned Streaming Electrons in the Near-Earth Magnetotail Reconnection2019In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 46, no 10, p. 5045-5054Article in journal (Refereed)
    Abstract [en]

    We analyze Magnetospheric Multiscale Mission observations of whistler waves and associated electron field-aligned crescent distribution in the vicinity of the magnetotail near-Earth X-line. The whistler waves propagate outward from the X-line in the neutral sheet. The associated field-aligned streaming electrons exhibit a crescent-like shape, with an inverse slope (df/d vertical bar v(parallel to)vertical bar > 0) at 1-5 keV. The parallel phase velocity of the waves is in the range (1-5 keV) of the inverse slope of the field-aligned crescents in the velocity space. We demonstrate that the observed whistler waves are driven by the electron field-aligned crescents through Landau resonance. The cyclotron resonance is at the high-energy tail with negligible free energy of pitch angle anisotropy in these events.

  • 48.
    Sun, W. J.
    et al.
    Chinese Acad Sci, Inst Geol & Geophys, Key Lab Earth & Planetary Phys, Beijing, Peoples R China.;Univ Michigan, Dept Climate & Space Sci & Engn, Ann Arbor, MI 48109 USA.;Peking Univ, Sch Earth & Space Sci, Beijing, Peoples R China.;Chinese Acad Sci, Key Lab Lunar & Deep Space Explorat, Natl Astron Observ, Beijing, Peoples R China..
    Slavin, J. A.
    Univ Michigan, Dept Climate & Space Sci & Engn, Ann Arbor, MI 48109 USA..
    Dewey, R. M.
    Univ Michigan, Dept Climate & Space Sci & Engn, Ann Arbor, MI 48109 USA..
    Raines, J. M.
    Univ Michigan, Dept Climate & Space Sci & Engn, Ann Arbor, MI 48109 USA..
    Fu, S. Y.
    Peking Univ, Sch Earth & Space Sci, Beijing, Peoples R China..
    Wei, Y.
    Chinese Acad Sci, Inst Geol & Geophys, Key Lab Earth & Planetary Phys, Beijing, Peoples R China..
    Karlsson, Tomas
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Poh, G. K.
    Univ Michigan, Dept Climate & Space Sci & Engn, Ann Arbor, MI 48109 USA..
    Jia, X.
    Univ Michigan, Dept Climate & Space Sci & Engn, Ann Arbor, MI 48109 USA..
    Gershman, D. J.
    NASA, Geospace Phys Lab, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Zong, Q. G.
    Peking Univ, Sch Earth & Space Sci, Beijing, Peoples R China..
    Wan, W. X.
    Chinese Acad Sci, Inst Geol & Geophys, Key Lab Earth & Planetary Phys, Beijing, Peoples R China..
    Shi, Q. Q.
    Shandong Univ, Sch Space Sci & Phys, Shandong Prov Key Lab Opt Astron & Solar Terr Env, Weihai, Peoples R China..
    Pu, Z. Y.
    Peking Univ, Sch Earth & Space Sci, Beijing, Peoples R China..
    Zhao, D.
    Peking Univ, Sch Earth & Space Sci, Beijing, Peoples R China..
    A Comparative Study of the Proton Properties of Magnetospheric Substorms at Earth and Mercury in the Near Magnetotail2018In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 45, no 16, p. 7933-7941Article in journal (Refereed)
    Abstract [en]

    The variations of plasma sheet proton properties during magnetospheric substorms at Earth and Mercury are comparatively studied. This study utilizes kappa distributions to interpret proton properties at both planets. Proton number densities are found to be around an order of magnitude higher, temperatures several times smaller, and kappa values broader at Mercury than at Earth. Protons become denser and cooler during the growth phase, and are depleted and heated after the dipolarizations in both magnetospheres. The changes of kappa at Earth are generally small (<20%), indicating that spectrum-preserving processes, like adiabatic betatron acceleration, play an important role there, while variations of kappa at Mercury are large (>60%), indicating the importance of spectrum-altering processes there, such as acceleration due to nonadiabatic