Ultrafast electron holes in plasma phase space dynamics

Seyyed Mehdi Hosseini Jenab,Ioannis Kourakis,Gert Brodin,James Juno

doi:10.1038/s41598-021-95652-w

Seyyed Mehdi Hosseini Jenab, Ioannis Kourakis + Show 2 more

Open Access

https://doi.org/10.1038/s41598-021-95652-w

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Abstract

Electron holes (EH) are localized modes in plasma kinetic theory which appear as vortices in phase space. Earlier research on EH is based on the Schamel distribution function (df). A novel df is proposed here, generalizing the original Schamel df in a recursive manner. Nonlinear solutions obtained by kinetic simulations are presented, with velocities twice the electron thermal speed. Using 1D-1V kinetic simulations, their propagation characteristics are traced and their stability is established by studying their long-time evolution and their behavior through mutual collisions.

Highlights

Electron holes (EH) are localized modes in plasma kinetic theory which appear as vortices in phase space
Plasma phase-space dynamics is tacitly characterized by the occurrence of electron holes, a term describing a localized plasma region where electrons are trapped by the electric potential stemming from their own selfgenerated density variation, as a localized electron depletion region occurs in a self-consistent manner
Saeki et al.[5] studied electron holes experimentally using a Q-plasma machine and via kinetic simulations; they reported structures moving at the electron thermal speed, which they identified as solitons

Summary

Introduction

Electron holes (EH) are localized modes in plasma kinetic theory which appear as vortices in phase space. In order to construct electron holes in a self-consistent manner within a kinetic model, one may either start with an arbitrary potential profile and proceed by deriving the distribution function (df) of an electron hole, or, inversely, start with a predefined df for the trapped electrons and derive the associated potential profile. The former (integral equation) method, due to Bernstein, Greene and Kruskal[4] leads to an infinity of solutions whose dynamical stability is not prescribed. It is important to realize that these structures are distinct in both their

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