Hybrid simulation of a parallel collisionless shock in the Large Plasma Device

TL;DR

This study uses hybrid kinetic/MHD simulations to demonstrate the formation of a parallel collisionless shock in the Large Plasma Device, highlighting the role of debris ions and upstream turbulence in shock development.

Contribution

First simulation to show shock formation in LAPD parameters, revealing debris ion dynamics and upstream turbulence characteristics.

Findings

Shock begins forming within available space in LAPD.

Debris ions excite magnetic fluctuations and transfer energy to hydrogen ions.

Upstream turbulence is dominated by right-hand resonant instability.

Abstract

We present two-dimensional hybrid kinetic/magnetohydrodynamic simulations of planned laser-ablation experiments in the Large Plasma Device (LAPD). Our results, based on parameters which have been validated in previous experiments, show that a parallel collisionless shock can begin forming within the available space. Carbon-debris ions that stream along the magnetic-field direction with a blow-off speed of four times the Alfven velocity excite strong magnetic fluctuations, eventually transfering part of their kinetic energy to the surrounding hydrogen ions. This acceleration and compression of the background plasma creates a shock front, which satisfies the Rankine-Hugoniot conditions and can therefore propagate on its own. Furthermore, we analyze the upstream turbulence and show that it is dominated by the right-hand resonant instability.