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  • 101.
    Block, Lars P
    et al.
    KTH, Tidigare Institutioner, Alfvénlaboratoriet. KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    Lazutin, L. L.
    Riedler, W.
    The Role of Scientific Ballooning for Exploration of the Magnetosphere1984Rapport (Annet vitenskapelig)
  • 102.
    Blomberg, Lars
    KTH, Tidigare Institutioner, Alfvénlaboratoriet. KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    Mercury's magnetosphere, exosphere and surface: Low-frequency field and wave measurements as a diagnostic tool1997Inngår i: Planetary and Space Science, ISSN 0032-0633, E-ISSN 1873-5088, Vol. 45, nr 1, s. 143-148Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Diagnostics that can be made with combined electric and magnetic field measurements at Mercury are reviewed. Fundamental electrodynamic questions which can be answered by means of a Mercury Orbiter are discussed. These include, solar wind-magnetosphere coupling, coupling to low altitude, exospheric or planetary surface conductivity, auroral particle acceleration, and magnetospheric substorms. It is concluded that a comprehensive instrumentation package for low-frequency fields and waves on a future Mercury Orbiter mission may yield significant new information of interest to magnetospheric as well as to planetary physics in general. (C) 1997 Elsevier Science Ltd.

  • 103.
    Blomberg, Lars
    KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik. KTH, Tidigare Institutioner, Alfvénlaboratoriet.
    Potential- och konduktivitetsfördelningar i jonosfären under inflytande av Birkelandströmmar1986Independent thesis Advanced level (degree of Master (Two Years)), 12 poäng / 18 hpOppgave
  • 104.
    Blomberg, Lars
    KTH, Tidigare Institutioner, Alfvénlaboratoriet. KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    Viking observations of dayside high-latitude electric fields1994Inngår i: Physical Signatures of Magnetospheric Boundary Layer Processes, 1994Konferansepaper (Fagfellevurdert)
  • 105.
    Blomberg, Lars
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    Cumnock, Judy
    KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    Diagnosing the Mercury Plasma Environment Using Low-Frequency Electric Field Measurements2006Inngår i: Advances in Geosciences, Volume 3: Planetary Science / [ed] Anil Bhardwaj, World Scientific Co., Pte. Ltd., Singapore , 2006, s. 63-70Konferansepaper (Fagfellevurdert)
  • 106.
    Blomberg, Lars G.
    et al.
    KTH, Tidigare Institutioner, Alfvénlaboratoriet. KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    Cumnock, J. A.
    KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik. KTH, Tidigare Institutioner, Alfvénlaboratoriet.
    Eriksson, A. I.
    The martian plasma environment: Electric field and Langmuir probe diagnostics2003Inngår i: IEEE Transactions on Plasma Science, ISSN 0093-3813, E-ISSN 1939-9375, Vol. 31, nr 6, s. 1232-1236Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The plasma environment of Mars has been studied by a small handful of spacecraft. From the sparse observations that exist, one may conclude that the solar wind-Martian magnetosphere interaction is different in significant ways from the solar wind's interaction with Earth's magnetosphere. Mars offers an opportunity to make significant advances in our understanding of the fundamentals of the solar wind's interaction with cold celestial bodies, with suitable plasma instrumentation orbiting the planet. We briefly review what is known about Mars' plasma environment and address some scientific topics that can be studied by proper plasma instrumentation in Mars' vicinity, in particular the scientific potential of Langmuir probe measurements. Finally, we exemplify how the studies may contribute to an enhanced understanding not only of the plasma surrounding Mars, but also of the planet itself and its neutral atmosphere.

  • 107.
    Blomberg, Lars G.
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    Cumnock, Judy
    KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    Electrodynamics of transpolar aurorae2005Inngår i: SOLAR WIND-MAGNETOSPHERE-IONOSPHERE DYNAMICS AND RADIATION MODELS, 2005, Vol. 36, nr 10, s. 1785-1790Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Polar UV image and Astrid-2 electric and magnetic field data are used to study the evolution of the electrodynamical configuration of the high-latitude ionosphere during a 5-h transpolar arc event. During the course of the event we observe Sunward convection in narrow regions associated with pairs Of upward and downward transpolar are-related field-aligned currents. We also observe Sunward convection deriving from more remotely located field-aligned currents as well as stagnant convection in the centre of the polar region associated with a decoupling of the dawn and dusk side current systems. Schematic pictures of the current closure and convective flows are presented for a variety Of configurations. The different states evolve naturally into each other and do not represent fundamentally different magnetospheric configurations.

  • 108.
    Blomberg, Lars G.
    et al.
    KTH, Tidigare Institutioner, Alfvénlaboratoriet.
    Cumnock, Judy
    KTH, Tidigare Institutioner, Alfvénlaboratoriet.
    On electromagnetic phenomena in Mercury's magnetosphere2004Inngår i: Mercury, Mars and Saturn / [ed] Grard, R; Masson, PL; Gombosi, TI, OXFORD: Pergamon Press, 2004, Vol. 33, nr 12, s. 2161-2165Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Mercury has a small but intriguing magnetosphere. In this brief review, we discuss some similarities and differences between Mercury's and Earth's magnetospheres. In particular, we discuss how electric and magnetic field measurements can be used as a diagnostic tool to improve our understanding of the dynamics of Mercury's magnetosphere. These points are of interest to the upcoming ESA-JAXA BepiColombo mission to Mercury.

  • 109.
    Blomberg, Lars G.
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik. KTH, Skolan för elektro- och systemteknik (EES), Centra, Alfvénlaboratoriet.
    Cumnock, Judy
    KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik. KTH, Skolan för elektro- och systemteknik (EES), Centra, Alfvénlaboratoriet.
    Alexeev, I.I.
    Belenkaya, E. S.
    Bobrovnikov, S. Y.
    Kalegaev, V. V.
    Transpolar aurora: time evolution, associated convection patterns, and a possible cause2005Inngår i: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 23, nr 5, s. 1917-1930Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present two event studies illustrating the detailed relationships between plasma convection, field-aligned currents, and polar auroral emissions, as well as illustrating the influence of the Interplanetary Magnetic Field's y-component on theta aurora development. The transpolar are of the theta aurorae moves across the entire polar region and becomes part of the opposite side of the auroral oval. Electric and magnetic field and precipitating particle data are provided by DMSP, while the POLAR UVI instrument provides measurements of auroral emissions. Ionospheric electrostatic potential patterns are calculated at different times during the evolution of the theta aurora using the KTH model. These model patterns are compared to the convection predicted by mapping the magnetopause electric field to the ionosphere using the Paraboloid Model of the magnetosphere. The model predicts that parallel electric fields are set up along the magnetic field lines projecting to the transpolar aurora. Their possible role in the acceleration of the auroral electrons is discussed.

  • 110.
    Blomberg, Lars G.
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    Cumnock, Judy
    KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    Glassmeier, K. H.
    Treumann, R. A.
    Plasma waves in the Hermean magnetosphere2007Inngår i: Space Science Reviews, ISSN 0038-6308, E-ISSN 1572-9672, Vol. 132, nr 04-feb, s. 575-591Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Hermean magnetosphere is likely to contain a number of wave phenomena. We briefly review what little is known so far about fields and waves around Mercury. We further discuss a number of possible phenomena, including ULF pulsations, acceleration-related radiation, bow shock waves, bremsstrahlung (or braking radiation), and synchrotron radiation. Finally, some predictions are made as to the likelihood that some of these types of wave emission exist.

  • 111.
    Blomberg, Lars G.
    et al.
    KTH, Tidigare Institutioner, Alfvénlaboratoriet. KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    Marklund, Göran T.
    KTH, Tidigare Institutioner, Alfvénlaboratoriet. KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    High-Latitude Convection Patterns For Various Large-Scale Field-Aligned Current Configurations1991Inngår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 18, nr 4, s. 717-720Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The large-scale field-aligned current system for persistent northward interplanetary magnetic field (IMF) is typically different from that for persistent southward IMF. One characteristic difference is that for northward IMF there is often a large-scale field-aligned current system poleward of the main auroral oval. This current system (the NBZ current) typically occupies a large fraction of the region poleward of the region 1 and 2 currents. The present paper models the high-latitude convection as a function of the large-scale field-aligned currents. In particular, a possible evolution of the convection pattern as the current system changes from a typical configuration for southward IMF to a configuration representing northward IMF (or vice versa) is presented. Depending on additional assumptions, for example about the y-component of the IMF, the convection pattern could either turn directly from a two-cell type to a four-cell type, or a three-cell type pattern could show up as an intermediate state. An interesting although rather surprising result of this study is that different ways of balancing the NBZ currents has a minor influence on the large-scale convection pattern.

  • 112.
    Blomberg, Lars G.
    et al.
    KTH, Tidigare Institutioner, Alfvénlaboratoriet. KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    Marklund, Göran T.
    KTH, Tidigare Institutioner, Alfvénlaboratoriet. KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    Lindqvist, Per-Arne
    KTH, Tidigare Institutioner, Alfvénlaboratoriet. KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    Primdahl, F.
    Brauer, P.
    Bylander, Lars
    KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik. KTH, Tidigare Institutioner, Alfvénlaboratoriet.
    Cumnock, Judy
    KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik. KTH, Tidigare Institutioner, Alfvénlaboratoriet.
    Eriksson, Stefan
    KTH, Tidigare Institutioner, Alfvénlaboratoriet.
    Ivchenko, Nickolay V.
    KTH, Tidigare Institutioner, Alfvénlaboratoriet. KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    Karlsson, Tomas
    KTH, Tidigare Institutioner, Alfvénlaboratoriet. KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    Kullen, Anita
    KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik. KTH, Tidigare Institutioner, Alfvénlaboratoriet.
    Merayo, J. M. G.
    Pedersen, E. B.
    Petersen, J. R.
    EMMA - the electric and magnetic monitor of the aurora on Astrid-22004Inngår i: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 22, nr 1, s. 115-123Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Astrid-2 mission has dual primary objectives. First, it is an orbiting instrument platform for studying auroral electrodynamics. Second, it is a technology demonstration of the feasibility of using micro-satellites for innovative space plasma physics research. The EMMA instrument, which we discuss in the present paper, is designed to provide simultaneous sampling of two electric and three magnetic field components up to about 1 kHz. The spin plane components of the electric field are measured by two pairs of opposing probes extended by wire booms with a separation distance of 6.7 m. The probes have titanium nitride (TiN) surfaces. which has proved to be a material with excellent properties for providing good electrical contact between probe and plasma. The wire booms are of a new design in which the booms in the stowed position are wound around the exterior of the spacecraft body. The boom system was flown for the first time on this mission and worked flawlessly. The magnetic field is measured by a tri-axial fluxgate sensor located at the tip of a rigid. hinged boom extended along the spacecraft spin axis and facing away from the Sun. The new advanced-design fluxgate magnetometer uses digital signal processors for detection and feedback, thereby reducing the analogue circuitry to a minimum. The instrument characteristics as well as a brief review of the science accomplished and planned are presented.

  • 113.
    Blomberg, Lars
    et al.
    KTH, Tidigare Institutioner, Alfvénlaboratoriet. KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    Lindqvist, Per-Arne
    KTH, Tidigare Institutioner, Alfvénlaboratoriet. KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    Marklund, Göran
    KTH, Tidigare Institutioner, Alfvénlaboratoriet. KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    Viking observations of electric fields1992Inngår i: Study of the Solar-Terrestrial System, 1992, Vol. 346, s. 269-274Konferansepaper (Annet vitenskapelig)
  • 114.
    Blomberg, Lars
    et al.
    KTH, Tidigare Institutioner.
    Marklund, Göran
    KTH, Tidigare Institutioner.
    A Numerical Model of Ionospheric Convection Derived From Field-Aligned Currents and the Corresponding Conductivity1988Rapport (Annet vitenskapelig)
  • 115.
    Blomberg, Lars
    et al.
    KTH, Tidigare Institutioner, Alfvénlaboratoriet.
    Marklund, Göran
    KTH, Tidigare Institutioner, Alfvénlaboratoriet.
    A Numerical Model of Ionospheric Convection Derived From Field-Aligned Currents and the Corresponding Conductivity1991Rapport (Annet vitenskapelig)
  • 116.
    Blomberg, Lars
    et al.
    KTH, Tidigare Institutioner, Alfvénlaboratoriet. KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    Marklund, Göran
    KTH, Tidigare Institutioner, Alfvénlaboratoriet. KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    High-latitude electrodynamics and aurorae during northward IMF1993Inngår i: Auroral Plasma Dynamics, Washington, DC: American Geophysical Union (AGU), 1993, s. 55-68Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    The large-scale auroral morphology and its associated electrodynamics for northward interplanetary magnetic field (IMF) is characteristically different from that for southward IMF. For northward IMF significant auroral activity is often present poleward of the “normal” auroral oval, and a number of different polar auroral configurations can occur. Two extreme situations which are considered here are either one where one or more discrete arcs separated from the “normal” oval are present in the polar region, or one where diffuse auroral activity is found in a large fraction of this region. The latter case might be associated with so-called NBZ (field-aligned) currents. We briefly review the typical signatures in terms of optical emissions, field-aligned currents, electric fields, and plasma convection usually encountered in the polar region when IMF Bz<0, and their interrelationships. This is the starting point for a more detailed discussion, driven by modeling results, of the relationships between electric field, field-aligned current, and conductivity in the two distinct situations mentioned. In particular we discuss the influence the polar field-aligned currents have on the convection pattern, on the small as well as on the large scale. As expected, currents associated with discrete isolated arcs give rise mainly to small-scale modifications, whereas currents related to auroral activity in an expanded oval can modify the overall convection pattern substantially.

  • 117.
    Blomberg, Lars
    et al.
    KTH, Tidigare Institutioner.
    Marklund, Göran
    KTH, Tidigare Institutioner.
    The Influence of Conductivities Consistent With Field-Aligned Currents on High-Latitude Convection Patterns1988Rapport (Annet vitenskapelig)
  • 118.
    Blomberg, Lars
    et al.
    KTH, Tidigare Institutioner, Alfvénlaboratoriet. KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    Marklund, Göran
    KTH, Tidigare Institutioner, Alfvénlaboratoriet. KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    The influence of conductivities consistent with field-aligned currents on high-latitutde convection patterns1988Inngår i: Journal of Geophysical Research - Space Physics, ISSN 0148-0227, Vol. 93, nr A12, s. 14493-14499Artikkel i tidsskrift (Fagfellevurdert)
  • 119.
    Blomberg, Lars
    et al.
    KTH, Tidigare Institutioner, Alfvénlaboratoriet.
    Marklund, Göran
    KTH, Tidigare Institutioner, Alfvénlaboratoriet.
    Lindqvist, Per-Arne
    KTH, Tidigare Institutioner, Alfvénlaboratoriet.
    Primdahl, F.
    Brauer, P.
    Bylander, Lars
    KTH, Tidigare Institutioner, Alfvénlaboratoriet.
    Cumnock, Judy
    KTH, Tidigare Institutioner, Alfvénlaboratoriet.
    Eriksson, S.
    Ivchenko, Nickolay
    KTH, Tidigare Institutioner, Alfvénlaboratoriet.
    Karlsson, Tomas
    KTH, Tidigare Institutioner, Alfvénlaboratoriet.
    Kullen, Anita
    KTH, Tidigare Institutioner, Alfvénlaboratoriet.
    Merayo, J. M. G.
    Pedersen, E. B.
    Petersen, J. R.
    The EMMA Instrument on the Astrid-2 Micro-Satellite2003Rapport (Annet vitenskapelig)
  • 120.
    Blomberg, Lars
    et al.
    KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    Wahlund, Jan-Erik
    Swedish Institute of Space Physics, Uppsala.
    Cumnock, Judy
    KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    Marklund, Göran
    KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    Lindqvist, Per-Arne
    KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    Morooka, Michiko
    Swedish Institute of Space Physics, Uppsala.
    André, Mats
    Swedish Institute of Space Physics, Uppsala.
    Eriksson, Anders
    Swedish Institute of Space Physics, Uppsala.
    Electric Field Diagnostics in the Jovian System: Brief Scientific Case and Instrumentation Overview2006Inngår i: Proceedings of the 6th IAA International Conference on Low-Cost Planetary Missions, 2006, s. 335-340Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    The Jovian plasma environment exhibits a variety of plasma flow interactions with magnetised as well as unmagnetised bodies, making it a good venue for furthering our understanding of solar wind - magnetosphere / ionosphere interactions.

    On an overall scale the solar wind interacts with the Jovian magnetosphere, much like at Earth but with vastly different temporal and spatial scales. Inside the Jovian magnetosphere the co-rotating plasma interacts with the inner moons. The latter interaction is slower and more stable than the corresponding interaction between the solar wind and the planets, and can thus provide additional information on the principles of the interaction mechanisms.

    Because of the wealth of expected low-frequency waves, as well as the predicted quasi-static electric fields and plasma drifts in the interaction regions between different parts of the Jovian system, a most valuable component in future payloads would be a double-probe electric field instrument. Recent developments in low-mass instrumentation facilitate electric field measurements on spinning planetary spacecraft, which we here exemplify.

  • 121. Boehm, M. H.
    et al.
    CLEMMONS, J
    WAHLUND, JE
    ERIKSSON, A
    ELIASSON, L
    Blomberg, Lars
    KTH, Tidigare Institutioner, Alfvénlaboratoriet. KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    KINTNER, P
    HOFNER, H
    Observations of an  upward-directed electron beam with the perpendicular temperature of the cold ionosphere1995Inngår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 22, s. 2103-2106Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Freja TESP electron spectrometer has repeatedly observed similar to 100 eV - 1 keV upward-directed, anti-field-aligned electron beams near 1700 km altitude in the auroral zone. A particularly intense event, at energies up to 2 keV, is described. The beam perpendicular temperature T perpendicular to(e)), was as low as 0.1-0.2 eV at 100-200 eV parallel energy. The 10-15 s period of upward fluxes was coincident with a low density (similar to 10 cm(-3)) period and a similar to 5 keV ion conic. Strong low frequency waves and the lack of any downward motion in the simultaneously observed ion conic suggest a strong element of wave acceleration, while electric field and ion loss cone measurements provide limited evidence of potential acceleration to a fraction of the observed energies.

  • 122.
    Bohm, Martin
    KTH, Tidigare Institutioner, Alfvénlaboratoriet.
    A users guide for the code XPDP1, version 3.1 and the modified version MODXPDP1. To be run on HP workstation 712/80 with HP-UX version 09.03 and a digital VXT 2000+ terminal1995Rapport (Annet vitenskapelig)
  • 123.
    Bohm, Martin
    KTH, Tidigare Institutioner, Alfvénlaboratoriet.
    Experimental Observations of Anomalous Potential Drops over Ion Density Cavities1991Rapport (Annet vitenskapelig)
  • 124.
    Bohm, Martin
    et al.
    KTH, Tidigare Institutioner, Alfvénlaboratoriet.
    Brenning, Nils
    KTH, Tidigare Institutioner, Alfvénlaboratoriet. KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    Fälthammar, Carl-Gunne
    KTH, Tidigare Institutioner, Alfvénlaboratoriet. KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    Dynamic trapping: Neutralization of positive space charge in a collisionless magnetized plasma1990Inngår i: Physical Review Letters, ISSN 00319007, Vol. 65, s. 859-866Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    It is shown by numerical simulations that in a collisionless plasma electron inertia leads to inefficient neutralization of positive space charge and allows large positive potentials (φ ≫ kTe/e) to be established and maintained on the time scale of ion motion. This is true even if the buildup of positive space charge is so slow that it corresponds to a small fraction of the random electron current of the surrounding plasma. A simple physical model clarifies the physics of the process and provides an analytical expression for the potential.

  • 125. Bohm, Martin
    et al.
    Brenning, Nils
    KTH, Tidigare Institutioner, Alfvénlaboratoriet. KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    Fälthammar, Carl-Gunne
    KTH, Tidigare Institutioner, Alfvénlaboratoriet. KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    Dynamic trapping of electrons in the porcupine ionospheric ion beam experiment1992Inngår i: Advances in Space Research, ISSN 02731177, Vol. 12, s. 9-14Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Electrons are needed to maintain quasineutrality in a case where positive ions are injected across the magnetic field into a limited volume in a magnetized plasma. In the absence of collisions, a positive potential builds up and traps the electrons which enter the region along the magnetic field. If the added density of ions exceeds the ambient density, large potential differences along the magnetic field can be maintained this way. The process explains several features of the Porcupine xenon ion beam injection experiment, where strong magnetic-field-aligned electric fields were measured in the vicinity of a xenon ion beam which was injected into the ambient ionosphere from a spinning subpayload. © 1992.

  • 126.
    Bohm, Martin
    et al.
    KTH, Tidigare Institutioner.
    Brenning, Nils
    KTH, Tidigare Institutioner.
    Fälthammar, Carl-Gunne
    KTH, Tidigare Institutioner.
    Dynamic Trapping of Electrons in the Porcupine Ionospheric Ion Beam Experiment1990Rapport (Annet vitenskapelig)
  • 127.
    Bohm, Martin
    et al.
    KTH, Tidigare Institutioner.
    Torvén, Staffan
    KTH, Tidigare Institutioner.
    Extended Potential Drops Preceding Double Layer Formation in a Triple Plasma Device1986Rapport (Annet vitenskapelig)
  • 128.
    Bohm, Martin
    et al.
    KTH, Tidigare Institutioner, Alfvénlaboratoriet.
    Torvén, Staffan
    KTH, Tidigare Institutioner, Alfvénlaboratoriet.
    Potential Drops Supported by Ion Density Cavities in the Dynamic Response of a Plasma Diode to an Applied Field1990Rapport (Annet vitenskapelig)
  • 129.
    Bohm, Martin
    et al.
    KTH, Tidigare Institutioner, Alfvénlaboratoriet.
    Torvén, Staffan
    KTH, Tidigare Institutioner, Alfvénlaboratoriet.
    The Dynamic Response of an Inhomogeneous Plasma Diode to an Applied Electric Field1990Rapport (Annet vitenskapelig)
  • 130. Bohm, P.
    et al.
    Aftanas, M.
    Bilkova, P.
    Stefanikova, E.
    Mikulin, O.
    Melich, R.
    Janky, F.
    Havlicek, J.
    Sestak, D.
    Weinzettl, V.
    Stockel, J.
    Hron, M.
    Panek, R.
    Scannell, R.
    Frassinetti, Lorenzo
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Fassina, A.
    Naylor, G.
    Walsh, M. J.
    Edge Thomson scattering diagnostic on COMPASS tokamak: Installation, calibration, operation, improvements2014Inngår i: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 85, nr 11, s. 11E431-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The core Thomson scattering diagnostic (TS) on the COMPASS tokamak was put in operation and reported earlier. Implementation of edge TS, with spatial resolution along the laser beam up to similar to 1/100 of the tokamak minor radius, is presented now. The procedure for spatial calibration and alignment of both core and edge systems is described. Several further upgrades of the TS system, like a triggering unit and piezo motor driven vacuum window shutter, are introduced as well. The edge TS system, together with the core TS, is now in routine operation and provides electron temperature and density profiles.

  • 131. Bohm, P
    et al.
    Bilkova, P
    Aftanas, M
    Stefanikova, E
    Mikulin, O
    Melich, R
    Janky, J
    Havlicek, H
    Sestak, D
    Weinzettl, V
    Stockel, A
    Hron, R
    Panek, R
    Scannell, R
    Frassinetti, Lorenzo
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Fassina, A
    Naylor, N
    Walsh, J
    Thomson Scattering on COMPASS tokamak: Plasma Edge Profile2013Inngår i: 16th International Symposium on Laser Aided Plasma Diagnostics Conference: Madison, Wisconsin, USA, 22-26 September, 2013, 2013Konferansepaper (Annet vitenskapelig)
  • 132.
    Bolin, Odd
    et al.
    KTH, Tidigare Institutioner, Alfvénlaboratoriet.
    Brenning, Nils
    KTH, Tidigare Institutioner, Alfvénlaboratoriet.
    A Numerical Study of the Electrodynamical Interaction Between Comet Shoemaker-Levy 9 and Jupiter1994Rapport (Annet vitenskapelig)
  • 133.
    Bolin, Odd
    et al.
    KTH, Tidigare Institutioner, Alfvénlaboratoriet.
    Brenning, Nils
    KTH, Tidigare Institutioner, Alfvénlaboratoriet.
    One-Dimensional Numerical Simulations of the Low-Frequency Electric Fields in the CRIT I and CRIT II Rocket Experiments1992Rapport (Annet vitenskapelig)
  • 134. Borodkina, I.
    et al.
    Borodin, D.
    Brezinsek, S.
    Tsvetkov, I. V.
    Kurnaev, V. A.
    Guillemaut, C.
    Maslov, M.
    Frassinetti, Lorenzo
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik.
    Intra-ELM tungsten sputtering in JET ITER-like wall: analytical studies of Be impurity and ELM type influence2017Inngår i: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T170, artikkel-id 014065Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The W source strength in JET H-mode discharges depends on the W sputtering in the inter and the intra-ELM phase due to impinging hydrogenic ions (D or H) and impurities (mainly Be). The analytical approach for interpretation of the Langmuir probe measurements is applied to model the ELM ion parallel transport and the W sputtering flux in intra-ELM and inter-ELM conditions in JET-ITER-like wall (ILW) hydrogen and deuterium plasmas. The impact of the Be ion charge and the Be concentration in the impinging ion flux on the W sputtering was estimated. Be2+ concentrations of 0.5% and 1% in the impinging ion flux increases the W sputtering fluence per ELM by 20%-30% and 35%-55% correspondingly with respect to pure deuterium plasma; the charge state of Be ions has no substantial effect on W sputtering in the intra-ELM phase. The analysis of JET ELMy H-mode discharges in hydrogen with different types of ELMs is presented. The W sputtering source under inter-and intra-ELM conditions is estimated using the analytical approach and validated by optical emission spectroscopy in these discharges. The intra-ELM W sputtering flux increases 2-4 times in comparison to the inter-ELM flux.

  • 135.
    Boström, Rolf
    KTH, Tidigare Institutioner, Alfvénlaboratoriet.
    Auroral Electric Fields1966Rapport (Annet vitenskapelig)
  • 136.
    Boström, Rolf
    KTH, Tidigare Institutioner.
    Currents in the Ionosphere and Magnetosphere1967Rapport (Annet vitenskapelig)
  • 137.
    Boström, Rolf
    KTH, Tidigare Institutioner.
    Electrodynamics of the Ionosphere1970Rapport (Annet vitenskapelig)
  • 138.
    Boström, Rolf
    KTH, Tidigare Institutioner.
    Mechanisms for Driving Birkeland Currents1975Rapport (Annet vitenskapelig)
  • 139.
    Boström, Rolf
    KTH, Tidigare Institutioner.
    Mechanisms for driving Birkeland currents1975Rapport (Annet vitenskapelig)
  • 140.
    Boström, Rolf
    KTH, Tidigare Institutioner.
    Models of force-free magnetic fields in resistive media1972Rapport (Annet vitenskapelig)
  • 141.
    Boström, Rolf
    KTH, Tidigare Institutioner.
    Polar Magnetic Substorms1970Rapport (Annet vitenskapelig)
  • 142.
    Boström, Rolf
    KTH, Tidigare Institutioner, Alfvénlaboratoriet.
    The Magnetic Field of Three-dimensional Magnetospheric Model Current Systems and Currents Induced in the Ground1969Rapport (Annet vitenskapelig)
  • 143.
    Bostöm, Rolf
    et al.
    KTH, Tidigare Institutioner.
    Fahleson, Ulf
    KTH, Tidigare Institutioner.
    Vertical propagation of time-dependent electric fields in the atmosphere and ionosphere1974Rapport (Annet vitenskapelig)
  • 144.
    Bostöm, Rolf
    et al.
    KTH, Tidigare Institutioner.
    Fahleson, Ulf
    KTH, Tidigare Institutioner.
    Olausson, L.
    Hallendal, G.
    Theory of time varying atmospheric electric fields and some applications to fields of ionospheric origin1973Rapport (Annet vitenskapelig)
  • 145. Boswell, C. J.
    et al.
    Berk, H. L.
    Borba, D.
    Johnson, Tomas
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik. KTH, Skolan för elektro- och systemteknik (EES), Centra, Alfvénlaboratoriet.
    Nave, M. F. F.
    Pinches, S. D.
    Sharapov, S. E.
    Observation and explanation of the JET n = 0 chirping mode2005Konferansepaper (Fagfellevurdert)
  • 146. Bowman, C.
    et al.
    Dickinson, D.
    Horvath, L.
    Lunniss, A. E.
    Wilson, H. R.
    Cziegler, I.
    Frassinetti, Lorenzo
    KTH, Skolan för elektro- och systemteknik (EES), Fusionsplasmafysik. KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    Gibson, K.
    Kirk, A.
    Lipschultz, B.
    Maggi, C. F.
    Roach, C. M.
    Saarelma, S.
    Snyder, P. B.
    Thornton, A.
    Wynn, A.
    Pedestal evolution physics in low triangularity JET tokamak discharges with ITER-like wall2018Inngår i: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 58, nr 1, artikkel-id 016021Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The pressure gradient of the high confinement pedestal region at the edge of tokamak plasmas rapidly collapses during plasma eruptions called edge localised modes (ELMs), and then re-builds over a longer time scale before the next ELM. The physics that controls the evolution of the JET pedestal between ELMs is analysed for 1.4 MA, 1.7 T, low triangularity, delta = 0.2, discharges with the ITER-like wall, finding that the pressure gradient typically tracks the ideal magneto-hydrodynamic ballooning limit, consistent with a role for the kinetic ballooning mode. Furthermore, the pedestal width is often influenced by the region of plasma that has second stability access to the ballooning mode, which can explain its sometimes complex evolution between ELMs. A local gyrokinetic analysis of a second stable flux surface reveals stability to kinetic ballooning modes; global effects are expected to provide a destabilising mechanism and need to be retained in such second stable situations. As well as an electronscale electron temperature gradient mode, ion scale instabilities associated with this flux surface include an electro-magnetic trapped electron branch and two electrostatic branches propagating in the ion direction, one with high radial wavenumber. In these second stability situations, the ELM is triggered by a peeling-ballooning mode; otherwise the pedestal is somewhat below the peeling-ballooning mode marginal stability boundary at ELM onset. In this latter situation, there is evidence that higher frequency ELMs are paced by an oscillation in the plasma, causing a crash in the pedestal before the peeling-ballooning boundary is reached. A model is proposed in which the oscillation is associated with hot plasma filaments that are pushed out towards the plasma edge by a ballooning mode, draining their free energy into the cooler plasma there, and then relaxing back to repeat the process. The results suggest that avoiding the oscillation and maximising the region of plasma that has second stability access will lead to the highest pedestal heights and, therefore, best confinement-a key result for optimising the fusion performance of JET and future tokamaks, such as ITER.

  • 147.
    Brandenburg, Axel
    et al.
    KTH, Centra, Nordic Institute for Theoretical Physics NORDITA.
    Durrer, Ruth
    Univ Geneva, Dept Phys Theor, Quai E Ansermet 24, CH-1211 Geneva 4, Switzerland.;Univ Geneva, Ctr Astroparticle Phys, Quai E Ansermet 24, CH-1211 Geneva 4, Switzerland..
    Kahniashvili, Tina
    Carnegie Mellon Univ, McWilliams Ctr Cosmol, 5000 Forbes Ave, Pittsburgh, PA 15213 USA.;Carnegie Mellon Univ, Dept Phys, 5000 Forbes Ave, Pittsburgh, PA 15213 USA.;Laurentian Univ, Dept Phys, Ramsey Lake Rd, Sudbury, ON P3E 2C6, Canada.;Ilia State Univ, Abastumani Astrophys Observ, 3-5 Cholokashvili St, Tbilisi 0194, Rep of Georgia..
    Mandalc, Sayan
    Carnegie Mellon Univ, McWilliams Ctr Cosmol, 5000 Forbes Ave, Pittsburgh, PA 15213 USA.;Carnegie Mellon Univ, Dept Phys, 5000 Forbes Ave, Pittsburgh, PA 15213 USA..
    Yin, Weichen Winston
    Carnegie Mellon Univ, McWilliams Ctr Cosmol, 5000 Forbes Ave, Pittsburgh, PA 15213 USA.;Carnegie Mellon Univ, Dept Phys, 5000 Forbes Ave, Pittsburgh, PA 15213 USA.;Univ Calif Berkeley, Dept Phys, Berkeley, CA 94720 USA..
    Statistical properties of scale-invariant helical magnetic fields and applications to cosmology2018Inngår i: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, nr 8, artikkel-id 034Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We investigate the statistical properties of isotropic, stochastic, Gaussian distributed, helical magnetic fields characterized by different shapes of the energy spectra at large length scales and study the associated realizability condition. We discuss smoothed magnetic fields that are commonly used when the primordial magnetic field is constrained by observational data. We are particularly interested in scale-invariant magnetic fields that can be generated during the inflationary stage by quantum fluctuations. We determine the correlation length of such magnetic fields and relate it to the infrared cutoff of perturbations produced during inflation. We show that this scale determines the observational signatures of the inflationary magnetic fields on the cosmic microwave background. At smaller scales, the scale-invariant spectrum changes with time. It becomes a steeper weak-turbulence spectrum at progressively larger scales. We show numerically that the critical length scale where this happens is the turbulent-diffusive scale, which increases with the square root of time.

  • 148.
    Brenning, Nils
    KTH, Tidigare Institutioner.
    A Necessary Condition for the Critical Ionization Velocity Interaction1982Rapport (Annet vitenskapelig)
  • 149.
    Brenning, Nils
    KTH, Tidigare Institutioner, Alfvénlaboratoriet. KTH, Skolan för elektro- och systemteknik (EES), Rymd- och plasmafysik.
    An Appendix to the Paper Te determination in low-density plasmas from the HeI 3889 Å and 5016 Å line intensities1981Rapport (Annet vitenskapelig)
  • 150.
    Brenning, Nils
    KTH, Tidigare Institutioner.
    An Improved Microwave Interferometer Technique for Plasma Density Measurements1983Rapport (Annet vitenskapelig)
1234567 101 - 150 of 1191
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