Strong collisionless coupling between an unmagnetized driver plasma and a magnetized background plasma

TL;DR

This paper develops a semi-analytical model to describe the strong collisionless coupling between an unmagnetized driver plasma and a magnetized background plasma, validated by simulations and experiments.

Contribution

The work introduces analytical expressions for key parameters of plasma coupling, enhancing understanding and diagnostics of collisionless plasma interactions.

Findings

Good agreement between model and simulations

Provides bounds for difficult-to-diagnose parameters

Applicable to laboratory and astrophysical plasmas

Abstract

Fast-exploding plasmas traveling though magnetized, collisionless plasmas can occur in a variety of physical systems, such as supernova remnants, coronal mass ejections, and laser-driven laboratory experiments. To study these systems, it is important to understand the coupling process between the plasmas. In this work, we develop a semi-analytical model of the parameters that characterize the strong collisionless coupling between an unmagnetized driver plasma and a uniformly and perpendicularly magnetized background plasma. In particular, we derive analytical expressions that describe the characteristic diamagnetic cavity and magnetic compression of these systems, such as their corresponding velocities, the compression ratio, and the maximum size of the cavity. The semi-analytical model is compared with collisionless 1D particle-in-cell simulations and experimental results with laser-driven plasmas, showing good agreement. The model allows us to provide bounds for parameters that are otherwise difficult to diagnose in experiments with similar setups.