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

Microinstabilities and plasma waves at Near-Sun Solar Wind collisionless Shocks: Predictions for PSP and SO

Zhongwei Yang1, Shuichi Matsukiyo2, Huasheng Xie3, Fan Guo4, Mingzhe Liu5, Xinliang Gao6, Quanming Lu6, and Chi Wang1
Zhongwei Yang et al.
  • 1National Space Science Center, Beijing, China (
  • 2Kyushu University, Fukuoka, Japan (
  • 3Hebei Key Laboratory of Compact Fusion, Langfang, China (
  • 4Los Alamos National Laboratory, NM, USA (
  • 5LESIA, Observatoire de Paris, Meudon, France (
  • 6University of Science and Technology of China, Hefei, China (

Microinstabilities and waves excited at perpendicular interplanetary shocks in the near-Sun solar wind are investigated by full particle-in-cell simulations. By analyzing the dispersion relation of fluctuating field components directly issued from the shock simulation, we obtain key findings concerning wave excitations at the shock front: (1) at the leading edge of the foot, two types of electrostatic (ES) waves are observed. The relative drift of the reflected ions versus the electrons triggers an electron cyclotron drift instability (ECDI) that excites the first ES wave. Because the bulk velocity of gyro-reflected ions shifts to the direction of the shock front, the resulting ES wave propagates obliquely to the shock normal. Immediately, a fraction of incident electrons are accelerated by this ES wave and a ring-like velocity distribution is generated. They can couple with the hot Maxwellian core and excite the second ES wave around the upper hybrid frequency. (2) From the middle of the foot all the way to the ramp, electrons can couple with both incident and reflected ions. ES waves excited by ECDI in different directions propagate across each other. Electromagnetic (EM) waves (X mode) emitted toward upstream are observed in both regions. They are probably induced by a small fraction of relativistic electrons. The impact of shock front rippling, Mach numbers, and dimensions on the ES wave excitation also will be discussed. Results shed new insight on the mechanism for the occurrence of ES wave excitations and possible EM wave emissions at young coronal mass ejection–driven shocks in the near-Sun solar wind.

How to cite: Yang, Z., Matsukiyo, S., Xie, H., Guo, F., Liu, M., Gao, X., Lu, Q., and Wang, C.: Microinstabilities and plasma waves at Near-Sun Solar Wind collisionless Shocks: Predictions for PSP and SO, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8114,, 2021.


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