Status: this preprint was under review for the journal ANGEO but the revision was not accepted.
Thermal electron anisotropy driven by kinetic Alfven waves in the Earth's magnetotail
Alexander Lukin,Anton Artemyev,Evgeny Panov,Rumi Nakamura,Anatoly Petrukovich,Robert Ergun,Barbara Giles,Yuri Khotyaintsev,Per Arne Lindqvist,Christopher Russell,and Robert Strangeway
Abstract. Thermal and subthermal electron populations in the Earth's magnetotail are usually characterized by pronounced field-aligned anisotropy that contributes to generation of strong electric currents within the magnetotail current sheet. Formation of this anisotropy requires electron field-aligned acceleration, and thus likely involves field-aligned electric fields. Such fields can be carried by various electromagnetic waves generated by fast plasma flows interacting with ambient magnetotail plasma. In this paper we consider one of the most intense observed wave emissions, kinetic Alfven waves, that often accompany fast plasma flows in the magnetotail. Using two tail seasons (2017, 2018) of MMS observations we have collected statistics of 80 fast plasma flows (or bursty bulk flows) events with distinctive enhancement of intensity of broadband electromagnetic waves (kinetic Alfven waves). We show correlation the intensity of electric fields of kinetic Alfven waves and characteristics of electron anisotropy distributions: the parallel electron anisotropy increases with magnitude of the wave parallel electric field. Also the energy range of this electron anisotropic population is well within the expected acceleration range for assumed kinetic Alfven waves. Our results indicate an important role of KAWs in production of thermal field-aligned electron population typically observed in the Earth's magnetotail.
How to cite. Lukin, A., Artemyev, A., Panov, E., Nakamura, R., Petrukovich, A., Ergun, R., Giles, B., Khotyaintsev, Y., Lindqvist, P. A., Russell, C., and Strangeway, R.: Thermal electron anisotropy driven by kinetic Alfven waves in the Earth's magnetotail, Ann. Geophys. Discuss. [preprint], https://doi.org/10.5194/angeo-2020-76, 2020.
Received: 18 Nov 2020 – Discussion started: 27 Nov 2020
We have collected statistics of 81 fast plasma flow events in the magnetotail with clear MMS observations of kinetic Alfven waves (KAWs). We show that KAWs electric field magnitudes correlates with thermal/subthermal electron flux anisotropy: wider energy range of electron anisotropic population corresponds to higher KAWs’ electric field intensity. These results indicate on an important role of KAWs in production of thermal field-aligned electron population of the Earth’s magnetotail.
We have collected statistics of 81 fast plasma flow events in the magnetotail with clear MMS...