Perpendicular subcritical shock structure in a collisional plasma experiment

TL;DR

This paper investigates the structure of perpendicular subcritical shocks in a collisional plasma, demonstrating their formation, characteristics, and confirming the absence of hydrodynamic jumps and viscous dissipation through detailed laboratory measurements.

Contribution

It provides the first detailed experimental analysis of subcritical shock structures in a collisional plasma, including measurements and theoretical comparisons.

Findings

Existence of subcritical shocks in collisional plasma

Shock width approximately equals classical resistive diffusion length

Minimal heating (<10%) across the shock

Abstract

We present a study of perpendicular subcritical shocks in a collisional laboratory plasma. Shocks are produced by placing obstacles into the super-magnetosonic outflow from an inverse wire array z-pinch. We demonstrate the existence of subcritical shocks in this regime and find that secondary shocks form in the downstream. Detailed measurements of the subcritical shock structure confirm the absence of a hydrodynamic jump. We calculate the classical (Spitzer) resistive diffusion length and show that it is approximately equal to the shock width. We measure little heating across the shock (< 10 % of the ion kinetic energy) which is consistent with an absence of viscous dissipation.