Electron Beam Weibel Instability in the Collisionless Shock with Low Mach Number

TL;DR

This study uses particle-in-cell simulations to explore how the electron beam Weibel instability develops in low Mach number collisionless shocks, revealing the conditions under which it is excited by cold and hot electrons.

Contribution

It demonstrates that cold electrons in dilute plasmas can trigger the Weibel instability, and that hot electrons require acceleration to relativistic speeds to do so.

Findings

Weibel instability is excited by cold electrons in dilute plasmas.

Hot electrons need to be accelerated to relativistic velocities to trigger the instability.

An electrostatic shock forms and generates filamentary magnetic fields.

Abstract

The electron beam Weibel instability in the electrostatic collisionless shock is studied via particle in cell simulation. When the non-relativistic incoming plasmas collide with cold dilute plasmas, an electrostatic shock forms near the interface. Following that, a filamentary out-of-plane magnetic field is formed as a result of the Weibel instability. It is demonstrated that the anisotropy of incoming hot electrons is insufficient to trigger the Weibel instability. And the Weibel instability is excited by cold electrons in dilute plasmas. After being accelerated to relativistic velocities by the shock electric field into the dense plasmas, electrons in the dilute plasma have considerable anisotropy and can trigger the Weibel instability