Characterization of a plasma deflagration accelerator as an ELM replicator for PFC testing

Abstract

Transient events in fusion power plants such as DEMO and ITER are known to pose a severe threat to plasma facing components (PFCs) due to melting and erosion after repeated edge localized mode (ELM) loads. Experimental testing in situ of potential PFC materials at fusion relevant conditions is difficult and expensive, and no facility currently in operation accurately replicates the salient plasma environment. At Stanford University, an experimental facility designed to mimic the heat flux, particle fluence, and other key characteristics of ELMs and disruption events in a controlled setting is under development. A pulsed plasma accelerator operating in the deflagration mode is used to generate high velocity (40–100 km/s) directed plasma jets that are stagnated on target material samples. In this work, we present probe data characterizing the plasma parameters of the accelerated plume using hydrogen as the working gas, as well as preliminary target studies of copper tokens exposed to pulses at various total and peak shot energies. Results from the probe analysis indicate achieved energy fluxes and heat flux parameters that are ELM-like, and the observed damage morphologies on the witness plates indicate that initial surface roughness plays a significant role in the growth and characteristics of surface melt patterns.