Ion and Electron Dynamics in the Presence of Mirror, Electromagnetic Ion Cyclotron, and Whistler Waves

Abstract

The wave-particle cyclotron interaction is a basic process in collisionless plasmas, which results in the redistribution of the energy between plasma waves and charged particles. This paper presents an event observation in order to explore the dynamics of charged particles and plasma waves, i.e., mirror, electromagnetic ion cyclotron (EMIC), and whistler waves, in the Earth's magnetosheath. It shows that when ions have a high-speed streaming velocity parallel to the magnetic field, EMIC waves arise. We also find that the frequency distribution of nearly parallel and nearly antiparallel whistler waves depends on the parallel streaming velocity of electrons. Based on the linear kinetic theory and the fitting plasma parameters, we show that the differential flows among ion components can enhance the ion cyclotron anisotropy instability that is even stronger than the mirror instability. The differential electron flows induce an asymmetry of the growth rate of counter-propagating whistler waves in the electron cyclotron anisotropy instability. On the other hand, the low-frequency EMIC and transverse electromagnetic waves modulate the ion pitch angle distribution. Moreover, when charged particles flow across the magnetic field, both low-and high-energy electrons are deeply trapped by mirror waves. These results illustrate new features of the observed plasma waves and charged particles in the Earth's magnetosheath, which could inspire improvement of the wave models therein.

Spectra of Diffusion, Dispersion, and Dissipation for Kinetic Alfvénic and Compressive Turbulence: Comparison between Kinetic Theory and Measurements from MMS

“…According to the theory of waves in plasmas (see, for example, the textbooks by Stix 1992;Gary 1993), Alfvén waves at kinetic scales propagating at different angles show two distinct dispersion relations: negative (i.e., < ) for parallel propagating ion-cyclotron waves and quasi-perpendicular kinetic Alfvén waves, respectively. Such different characteristics of dispersion relations have been applied to diagnose the wave modes in space plasmas (e.g., Narita et al 2011;He et al 2013;Roberts et al 2015;Zhao 2015;Zhao et al 2019b). The k-filtering/wave-telescope tool has been successfully employed to measurements from Cluster and MMS to reconstruct the dispersion relation in frequency-wavenumber space (Sahraoui et al 2010;Narita et al 2011;Roberts et al 2015;Narita et al 2016).…”

Observation of High‐Frequency Electrostatic Waves in the Dip Region Ahead of Dipolarization Front

“…Multicomponent drifting bi-Maxwellian distributions (Zhao et al, 2019) are used to fit the positive slope of the field-aligned EDF:…”

“…Multicomponent drifting bi‐Maxwellian distributions (Zhao et al., 2019) are used to fit the positive slope of the field‐aligned EDF: where V th || = is the parallel thermal velocity derived from the parallel temperature T || , V th ⊥ = is the perpendicular thermal velocity derived from the perpendicular temperature, V d is the drifting velocity, and the m represents the particle mass. The fitting results are shown in Figures 3a and 3b (red lines).…”

Excitation of Whistler Waves Through the Bidirectional Field‐Aligned Electron Beams With Electron Temperature Anisotropy: MMS Observations

“…To investigate the excitation of the observed whistler waves, we conduct a linear analysis using PDRK (the kinetic plasma dispersion relation), which is a general kinetic dispersion relation solver for magnetized plasma (Xie & Xiao, 2016) and has been used in the analysis of plasma instabilities (e.g., Zhao et al, 2019; Zhao, Wang, Dunlop, et al, 2019) and 1D PIC simulations, namely, KEMPO1, which could simulate the nonlinear process involved in the micro‐instabilities (Matsumoto & Omura, 1985).…”