The Effect of Gas Dynamics in Plasma Gun Performance for Simulating Fusion Wall Response to Disruptions*

In this work, the suitability of a pulsed coaxial plasma accelerator to simulate the interaction of edge-localized modes with plasma first-wall materials is investigated. Experimental measurements are presented that focus on both the properties of the plasma flow and the manner in which such jets couple with material interfaces. Specific emphasis is placed on quantifying the variation in these properties using tungsten tokens exposed to the plasma plume. Time-resolved Schlieren visualization of the density gradient within the flow indicates the existence of two distinct modes with vastly different characteristic timescales, spatial evolution, and plasma properties. Time-resolved quantification of the associated plasma heat flux for both modes, including a range spanning 150 MW/m² - 10 GW/m², is presented using a fast thermocouple gauge, an IR camera, and a high-frequency two-color IR pyrometer. These diagnostics, in conjunction with a DSMC simulation of the expansion of neutral gas within the volume, are used to resolve the energy transfer dynamics of the heating process and provide an accurate description of the operational characteristics of plasma guns.