[P-EM13] Dynamics of the Inner Magnetospheric System

[PEM13-06] Energetic electron precipitation from the plasma sheet: comparison of ELFIN and ERG measurements

*Anton Artemyev¹、Xiaojia Zhang^2,1、Vassilis Angelopoulos¹、Yoshizumi Miyoshi³、Takefumi Mitani⁴、Takeshi Takashima⁴、Tomo Hori³、 Ayako Matsuoka⁵、Iku Shinohara⁴ (1.Institute of Geophysics and Planetary Physics at UCLA、2.Department of Physics, University of Texas at Dallas, Richardson, TX, USA、3.ISEE, Nagoya University, Nagoya, Japan、4.ISAS, JAXA, Sagamihara Japan、5.Graduate School of Science, Kyoto University, Kyoto, Japan)

キーワード：energetic electron precipitation, plasma sheet , isotropy boundary

During geomagnetic substorms, the Earth’s magnetotail plasma sheet is filled with energetic (below 200keV) electrons. In the meantime, large curvatures of magnetic field lines in the current sheet result in effective electron scattering and precipitation. In this presentation, we will show typical examples of such precipitation patterns as observed by low-altitude ELFIN CubeSats during different phases of geomagnetic substorms. We will compare isotropic electron fluxes measured by ELFIN and captured by ERG satellite, when it is projected from middle latitudes to the night-site plasma sheet, and by the near-equatorial THEMIS mission in the plasma sheet. Energy distributions of low-altitude fluxes are quantitatively close to the near-equatorial distributions, which justifies the investigation of the magnetotail current sheet reconfiguration using low-altitude measurements. We will also demonstrate that the magnetic field reconfiguration during the current sheet thinning (which lasts longer than an hour) results in a rapid shrinking of the low-altitude projection of the entire plasma sheet (from near-Earth, ~10R_E, to the lunar orbit ~60R_E) to 1-2 degrees of magnetic latitude in the ionosphere.