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Publications (7 of 7) Show all publications
Huang, S. Y., Yuan, Z. G., Fu, H. S., Vaivads, A., Sahraoui, F., Khotyaintsev, Y. V., . . . Wang, D. D. (2018). Observations of Whistler Waves in the Magnetic Reconnection Diffusion Region. In: 2ND URSI ATLANTIC RADIO SCIENCE MEETING (AT-RASC): . Paper presented at 2nd URSI Atlantic Radio Science Meeting (AT-RASC), MAY 28-JUN 01, 2018, Meloneras, SPAIN. IEEE
Open this publication in new window or tab >>Observations of Whistler Waves in the Magnetic Reconnection Diffusion Region
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2018 (English)In: 2ND URSI ATLANTIC RADIO SCIENCE MEETING (AT-RASC), IEEE , 2018Conference paper, Published paper (Refereed)
Abstract [en]

Whistler waves are believed to play an important role during magnetic reconnection. In this paper, we report the simultaneous occurrence of two types of the whistler waves in the magnetotail reconnection diffusion region. The first type is observed in the pileup region of downstream and propagates away along the field lines to downstream, and is possibly generated by the electron temperature anisotropy at the magnetic equator. The second type is found around the separatrix region and propagates towards the X-line, and is possibly aenerated by the electron beam-driven whistler instability or Cerenkov emission from electron phase-space holes. Our observations of two different types of whistler waves are well consistent with recent kinetic simulations, and suggest that the observed whistler waves are the consequences of magnetic reconnection.Moreover, we statistically investigate the whistler waves in the magnetotail reconnection region, and construct the global distribution and occurrence rate of the whistler waves based on the two-dimensional reconnection model. It is found that the occurrence rate of the whistler waves is large in the separatrix region (113,1B0j>0.4) and pileup region ([B,./Bol<0.2, 161>45'), but very small in the X-line region. The statistical results are well consistent with the case study.

Place, publisher, year, edition, pages
IEEE, 2018
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:kth:diva-253491 (URN)10.23919/URSI-AT-RASC.2018.8471382 (DOI)000462069500089 ()978-90-82598-73-5 (ISBN)
Conference
2nd URSI Atlantic Radio Science Meeting (AT-RASC), MAY 28-JUN 01, 2018, Meloneras, SPAIN
Note

QC 20190826

Available from: 2019-06-15 Created: 2019-06-15 Last updated: 2019-08-26Bibliographically approved
Graham, D. B., Khotyaintsev, Y. V., Vaivads, A. & Andre, M. (2016). Electrostatic solitary waves and electrostatic waves at the magnetopause. Journal of Geophysical Research - Space Physics, 121(4), 3069-3092
Open this publication in new window or tab >>Electrostatic solitary waves and electrostatic waves at the magnetopause
2016 (English)In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 121, no 4, p. 3069-3092Article in journal (Refereed) Published
Abstract [en]

Electrostatic solitary waves (ESWs) are characterized by localized bipolar electric fields parallel to the magnetic field and are frequently observed in space plasmas. In this paper a study of ESWs and field-aligned electrostatic waves, which do not exhibit localized bipolar fields, near the magnetopause is presented using the Cluster spacecraft. The speeds, length scales, field strengths, and potentials are calculated and compared with the local plasma conditions. A large range of speeds is observed, suggesting different generation mechanisms. In contrast, a smaller range of length scales normalized to the Debye length lambda(D) is found. For ESWs the average length between the positive and negative peak fields is 9 lambda(D), comparable to the average half wavelength of electrostatic waves. Statistically, the lengths and speeds of ESWs and electrostatic waves are shown to be similar. The length scales and potentials of the ESWs are consistent with predictions for stable electron holes. The maximum ESW potentials are shown to be constrained by the length scale and the magnetic field strength at the magnetopause and in the magnetosheath. The observed waves are consistent with those generated by the warm bistreaming instability, beam-plasma instability, and electron-ion instabilities, which account for the observed speeds and length scales. The large range of wave speeds suggests that the waves can couple different electron populations and electrons with ions, heating the plasma and contributing to anomalous resistivity.

National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:kth:diva-253470 (URN)10.1002/2015JA021527 (DOI)000379960300018 ()
Funder
Swedish National Space Board, 128/11:2 77/13
Note

QC 20190624

Available from: 2019-06-15 Created: 2019-06-15 Last updated: 2019-06-24Bibliographically approved
Li, W., Andre, M., Khotyaintsev, Y. V., Vaivads, A., Graham, D. B., Toledo-Redondo, S., . . . Strangeway, R. J. (2016). Kinetic evidence of magnetic reconnection due to Kelvin-Helmholtz waves. Geophysical Research Letters, 43(11), 5635-5643
Open this publication in new window or tab >>Kinetic evidence of magnetic reconnection due to Kelvin-Helmholtz waves
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2016 (English)In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 43, no 11, p. 5635-5643Article in journal (Refereed) Published
Abstract [en]

The Kelvin-Helmholtz (KH) instability at the Earth's magnetopause is predominantly excited during northward interplanetary magnetic field (IMF). Magnetic reconnection due to KH waves has been suggested as one of the mechanisms to transfer solar wind plasma into the magnetosphere. We investigate KH waves observed at the magnetopause by the Magnetospheric Multiscale (MMS) mission; in particular, we study the trailing edges of KH waves with Alfvenic ion jets. We observe gradual mixing of magnetospheric and magnetosheath ions at the boundary layer. The magnetospheric electrons with energy up to 80keV are observed on the magnetosheath side of the jets, which indicates that they escape into the magnetosheath through reconnected magnetic field lines. At the same time, the low-energy (below 100eV) magnetosheath electrons enter the magnetosphere and are heated in the field-aligned direction at the high-density edge of the jets. Our observations provide unambiguous kinetic evidence for ongoing reconnection due to KH waves.

Place, publisher, year, edition, pages
Blackwell Publishing, 2016
Keywords
kinetic evidence, reconnection, Kelvin-Helmholtz wave
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:kth:diva-253541 (URN)10.1002/2016GL069192 (DOI)000379851800012 ()2-s2.0-84977100261 (Scopus ID)
Funder
Swedish National Space Board, 164/14, 176/15
Note

QC 20190625

Available from: 2019-06-15 Created: 2019-06-15 Last updated: 2019-06-25Bibliographically approved
Huang, S. Y., Fu, H. S., Yuan, Z. G., Vaivads, A., Khotyaintsev, Y. V., Retino, A., . . . Zhou, X. (2016). Two types of whistler waves in the hall reconnection region. Journal of Geophysical Research - Space Physics, 121(7), 6639-6646
Open this publication in new window or tab >>Two types of whistler waves in the hall reconnection region
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2016 (English)In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 121, no 7, p. 6639-6646Article in journal (Refereed) Published
Abstract [en]

Whistler waves are believed to play an important role during magnetic reconnection. Here we report the near-simultaneous occurrence of two types of the whistler-mode waves in the magnetotail Hall reconnection region. The first type is observed in the magnetic pileup region of downstream and propagates away to downstream along the field lines and is possibly generated by the electron temperature anisotropy at the magnetic equator. The second type, propagating toward the X line, is found around the separatrix region and probably is generated by the electron beam-driven whistler instability or erenkov emission from electron phase-space holes. These observations of two different types of whistler waves are consistent with recent kinetic simulations and suggest that the observed whistler waves are a consequence of magnetic reconnection.

Keywords
magnetic reconnection, whistler wave, pileup region, separatrix
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:kth:diva-253488 (URN)10.1002/2016JA022650 (DOI)000383422100042 ()2-s2.0-84979527868 (Scopus ID)
Note

QC 20190625

Available from: 2019-06-15 Created: 2019-06-15 Last updated: 2019-06-25Bibliographically approved
Graham, D. B., Khotyaintsev, Y. V., Vaivads, A. & André, M. (2015). Electrostatic solitary waves with distinct speeds associated with asymmetric reconnection. Geophysical Research Letters, 42(2), 215-224
Open this publication in new window or tab >>Electrostatic solitary waves with distinct speeds associated with asymmetric reconnection
2015 (English)In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 42, no 2, p. 215-224Article in journal (Refereed) Published
Abstract [en]

Electrostatic solitary waves (ESWs) are observed at the magnetopause with distinct time scales. These ESWs are associated with asymmetric reconnection of the cold dense magnetosheath plasma with the hot tenuous magnetospheric plasma. The distinct time scales are shown to be due to ESWs moving at distinct speeds and having distinct length scales. The length scales are of order 5-50 Debye lengths, and the speeds range from approximate to 50 km s(-1) to approximate to 1000 km s(-1). The ESWs are observed near the reconnection separatrices. The observation of ESWs with distinct speeds suggests that multiple instabilities are occurring. The implications for reconnection at the magnetopause are discussed.

Keywords
electron solitary waves, magnetic reconnection, magnetopause
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-253471 (URN)10.1002/2014GL062538 (DOI)000349956000005 ()
Note

QC 20190624

Available from: 2019-06-15 Created: 2019-06-15 Last updated: 2019-06-24Bibliographically approved
Norgren, C., André, M., Graham, D. B. B., Khotyaintsev, Y. V. V. & Vaivads, A. (2015). Slow electron holes in multicomponent plasmas. Geophysical Research Letters, 42(18), 7264-7272
Open this publication in new window or tab >>Slow electron holes in multicomponent plasmas
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2015 (English)In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 42, no 18, p. 7264-7272Article in journal (Refereed) Published
Abstract [en]

Electrostatic solitary waves (ESWs), often interpreted as electron phase space holes, are commonly observed in plasmas and are manifestations of strongly nonlinear processes. Often slow ESWs are observed, suggesting generation by the Buneman instability. The instability criteria, however, are generally not satisfied. We show how slow electron holes can be generated by a modified Buneman instability in a plasma that includes a slow electron beam on top of a warm thermal electron background. This lowers the required current for marginal instability and allows for generation of slow electron holes for a wide range of beam parameters that covers expected plasma distributions in space, for example, in magnetic reconnection regions. At higher beam speeds, the electron-electron beam instability becomes dominant instead, producing faster electron holes. The range of phase speeds for this model is consistent with a statistical set of observations at the magnetopause made by Cluster.

Keywords
Multi-component plasma, Modified Buneman instability, Ion-electron instability, Slow electron holes
National Category
Fusion, Plasma and Space Physics
Identifiers
urn:nbn:se:kth:diva-253558 (URN)10.1002/2015GL065390 (DOI)000363412400004 ()2-s2.0-84945218399 (Scopus ID)
Funder
Swedish Research Council, 23/12:2
Note

QC 20190617

Available from: 2019-06-15 Created: 2019-06-15 Last updated: 2019-06-17Bibliographically approved
Graham, D. B., Khotyaintsev, Y. V., Vaivads, A., André, M. & Fazakerley, A. N. (2014). Electron Dynamics in the Diffusion Region of an Asymmetric Magnetic Reconnection. Physical Review Letters, 112(21), 215004
Open this publication in new window or tab >>Electron Dynamics in the Diffusion Region of an Asymmetric Magnetic Reconnection
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2014 (English)In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 112, no 21, p. 215004-Article in journal (Refereed) Published
Abstract [en]

During a magnetopause crossing near the subsolar point Cluster observes the ion diffusion region of antiparallel magnetic reconnection. The reconnecting plasmas are asymmetric, differing in magnetic field strength, density, and temperature. Spatial changes in the electron distributions in the diffusion region are resolved and investigated in detail. Heating of magnetosheath electrons parallel to the magnetic field is observed. This heating is shown to be consistent with trapping of magnetosheath electrons by parallel electric fields.

National Category
Fusion, Plasma and Space Physics Physical Sciences
Identifiers
urn:nbn:se:kth:diva-253472 (URN)10.1103/PhysRevLett.112.215004 (DOI)000336765200006 ()
Note

QC 20190624

Available from: 2019-06-15 Created: 2019-06-15 Last updated: 2019-06-24Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-1046-746x

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