EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Shock Acceleration of ~1-100 Kev Electrons at Earth's Bow Shock

Zixuan Liu1, Linghua Wang1, Liu Yang1, Wimmer-Schweingruber Robert2, Quanqi Shi3, and Bale Stuart4
Zixuan Liu et al.
  • 1School of Earth and Space Science, Peking University, Beijing, 100871, China
  • 2Institute of Experimental and Applied Physics, University of Kiel, Leibnizstrasse 11, D--24118 Kiel, Germany
  • 3School of Space Science and Physics, Institute of Space Sciences, Shandong University, Weihai, Shandong, 264209, China
  • 4Department of Physics and Space Sciences Laboratory, University of California, Berkeley, CA 94720, USA

We present a statistical study of in-situ shock acceleration of ~1-100 keV solar wind suprathermal electrons at Earth’s bow shock, by using Wind 3D plasma and energetic particle measurements in ambient solar wind and MMS measurements in shock downstream. We pick out 74 shock cases (1 quasi-parallel shock, 73 quasi-perpendicular shocks) during 2015 October - 2017 January, and classify them into 4 types according to their energy spectra in downstream: type 0 (23 cases) without significant electron acceleration after shock passage, type 1 (24 cases) with power-law spectrum, J ∝εβ1_dn, at ~0.8-10 keV, type 2 (16 cases) with power-law-spectrum at ~0.8-10 keV and significant flux enhancement above 30 keV, and type 3 (11 cases) with a clear double-power-law spectrum, J ∝ εβ1_dn (J ∝ εβ2_dn) when ε « εdntr  (ε » εdntr), bending down at εdntr ~20-90 keV. The spectral indexes at lower energies for type 1, type 2 and type 3, β1dn, range from 2.5 to 5, while the spectral indexes at higher energies for type 3, β2dn, range from 4 to 9, and all the spectral indexes have no significant correlation with those in ambient solar wind. Among the 4 types, type 3 is the strongest acceleration with the largest flux enhancement and the lowest β1dn. Besides, we find that the flux ratio between downstream and ambient solar wind Jdn/Jab is field-perpendicular for most cases in both low and high energies, and Jdn/Jab1dn) has positive (negative) correlations with θBn and magnetic field compression ratio, rB, which favor the shock drift acceleration (SDA) mechanism. However, Jdn/Jab has no correlation with the drift electric field Ed, while the normalized drift time, Td/Ttr, has a positive correlation with θBn, it suggests that θBn can influence electron drift time and thus influence the acceleration efficiency.

How to cite: Liu, Z., Wang, L., Yang, L., Robert, W.-S., Shi, Q., and Stuart, B.: Shock Acceleration of ~1-100 Kev Electrons at Earth's Bow Shock, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14279,, 2021.