[P-EM15] 宇宙プラズマ理論・シミュレーション

[PEM15-05] Trajectory analysis of energetic electrons in quasi-perpendicular shock structure

*大塚 史子¹、松清 修一¹、岡 光夫² (1.九州大学大学院総合理工学研究院、2.カリフォルニア大学バークレー校)

キーワード：準垂直衝撃波、電子加速、地球バウショック

Electrons are accelerated to very high, non-thermal energies at Earth's quasi-perpendicular bow shock. The shock front reflects some of the incoming solar wind particles, resulting in its characteristic internal structure, i.e., foot and overshoot in the magnetic field on the upstream and downstream sides, respectively, separated by the shock ramp. In this study, we performed PIC simulations to study how electrons are accelerated in such a complex, internal structure of quasi-perpendicular shocks. We used an ion-to-electron mass ratio, 625, that is one order of magnitude larger than that of previous PIC simulations of quasi-perpendicular shocks. The shock parameters are as follows. The Alfven Mach number is 7, upstream plasma beta is 0.3, the shock angles are 70 and 80 degrees.

We have found three types of accelerated electrons: trappings by the thin structures of magnetic trough and electrostatic potential in the shock transition region, a single reflection at the intense overshoot magnetic field, and multiple reflections between the first and second overshoots in the downstream region. To further explore each acceleration mechanism, we investigate which electric field component contributes to the energy gain in each type of the electrons. We also analyze the electromagnetic and electrostatic fields in the shock transition region. The result will be applied to MMS observations.