[P-EM17] 宇宙プラズマ科学

[PEM17-09] Statistical Study on Magnetic Surfing and Shock Drift Acceleration of Electrons at Quasi-Perpendicular Shocks

*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：電子加速、無衝突衝撃波

Electron acceleration is an important topic in astrophysical and space plasma physics. We have found a new mechanism of electron acceleration by magnetic surfing in a transition region of locally low Mach number, quasi-perpendicular shocks. In the mechanism electrons gain energy from the electrostatic component of oblique, dispersive phase-standing whistler waves while surfing along the magnetic troughs embedded in the shock overshoot. However, it is unclear what fraction of electrons are accelerated by the magnetic surfing process.

In this presentation, we perform test particle simulation using the electromagnetic fields, obtained from one-dimensional particle-in-cell simulations of quasi-perpendicular collisionless shocks. Time series analysis of electron trajectories distinguishes the magnetic surfing process from the so-called shock drift acceleration (SDA). From the analysis, we calculate the fractions of electron number and energy densities for each process. Preliminary result shows that the fraction of non-thermal electrons produced by magnetic surfing is 3.6 times that of SDA. We also discuss the effects of high-frequency electromagnetic waves near the electron plasma frequency on the magnetic surfing acceleration.