Optimizing an in-situ plasma discharge process for improving multi-MA accelerator performance

Sandia National laboratories is using a glow discharge to remove contaminants from Magnetically Insulated Transmission Line (MITL) surfaces in low impedance, multi-megaampere accelerators. Sandia's Z Machine (Z) deliver over 20 MA in 100 ns to targets via MITLs operating at lineal current densities between 0.1 and 5 MA/cm and with anode-cathode (AK) gap spacings varying from 3 to over 10 mm. Ohmic heating contributes to rapid surface heating and subsequent desorption of lightly bound, low-mass contaminants. Surfaces also melt and release bulk hydrogen into the growing electrode plasma. Though not fully understood, it is likely that these ionized species contribute to charge transport across the AK gap, shunting current and reducing HED target performance.