Practicality of magnetic compression for plasma density control

TL;DR

This paper investigates the practicality of using magnetic compression to control plasma density in accelerators, revealing complex shock dynamics and plasma heating effects that could be beneficial for accelerator applications.

Contribution

It provides the first detailed simulation-based analysis of rapid magnetic compression effects on plasma density, highlighting shock formation and plasma heating phenomena.

Findings

Formation of counter-propagating shock waves during compression

Large plasma heating observed at shock collision point

Plasma density becomes highly non-uniform after compression

Abstract

Plasma densification through magnetic compression has been suggested for time-resolved control of the wave properties in plasma-based accelerators. Using particle in cell simulations with real mass ratio, the practicality of large magnetic compression on timescales shorter than the ion gyro-period is investigated. For compression times shorter than the transit time of a compressional Alfven wave across the plasma slab, results show the formation of two counter-propagating shock waves, leading to a highly non-uniform plasma density profile. Furthermore, the plasma slab displays large hydromagnetic like oscillations after the driving field has reached steady state. Peak compression is obtained when the two shocks collide in the mid-plane. At this instant, very large plasma heating is observed, and plasma $\beta$ is estimated to be about $1$. Although these results point out a densification mechanism quite different and more complex than initially envisioned, these features could possibly be advantageous in particle accelerators.