Emergence of MHD structures in a collisionless PIC simulation plasma

TL;DR

This study uses PIC simulations to explore how collisionless plasmas develop MHD structures like shocks and discontinuities, revealing wave dispersion effects on shock transition layers.

Contribution

It demonstrates the emergence of MHD structures such as shocks and discontinuities in collisionless plasma simulations over MHD timescales.

Findings

Formation of a fast rarefaction wave during plasma expansion

Development of a tangential discontinuity separating dense and dilute plasmas

Widening of shock transition layer into nonlinear wave train due to dispersion

Abstract

The expansion of a dense plasma into a dilute plasma across an initially uniform perpendicular magnetic field is followed with a one-dimensional particle-in-cell (PIC) simulation over MHD time scales. The dense plasma expands in the form of a fast rarefaction wave. The accelerated dilute plasma becomes separated from the dense plasma by a tangential discontinuity at its back. A fast magnetosonic shock with the Mach number 1.5 forms at its front. Our simulation demonstrates how wave dispersion widens the shock transition layer into a train of nonlinear fast magnetosonic waves.