The Hall Term and Anomalous Resistivity Effects in Neon Gas-Puff Z-Pinches

TL;DR

This study compares experimental and simulation results of neon gas-puff Z-pinches, highlighting the importance of the Hall term and anomalous resistivity in accurately modeling plasma sheath structure and instability behaviors.

Contribution

It demonstrates the significance of including the Hall term and anomalous resistivity driven by lower-hybrid-drift instability in simulations for better agreement with experimental data.

Findings

Better reproduction of MRTI wavelength with Hall term and anomalous resistivity

More accurate modeling of cathode-anode gap polarity effects with Hall term

Plasma sheath width matches measurements when anomalous resistivity is included

Abstract

In this paper, we compare experimental and numerical simulation results to benchmark the PERSEUS code against gas-puff $Z$-pinch implosions on COBRA. We then use the code to investigate the structure of the plasma sheath. To this end, we study the morphology of the implosion, focusing on non-magnetohydrodynamical (MHD) effects such as electron drifts governed by the Hall term within the growing magneto-Rayleigh-Taylor instability (MRTI). The spatial wavelength of MRTI is better reproduced when both the Hall term and an anomalous resistivity driven by the electron drift are included. Additionally, cathode-anode gap polarity effects are more accurately captured when the Hall term is turned on. The plasma sheath structure, which includes both the accelerating piston driven by the magnetic pressure and the shockwave ahead of it, matches interferometric measurements in width only when a current-driven anomalous resistivity model is used. This anomalous resistivity is assumed to be driven by the lower-hybrid-drift instability, which generates small-scale turbulence with typical wavelengths < 30{\mu}m.