Power accounting of plasma discharges in the linear device Proto-MPEX

Proto-MPEX is a prototype device whose primary purpose is to develop the plasma heating source concepts for the Material Plasma Exposure eXperiment (MPEX), a steady-state linear device being developed to study plasma material interactions (PMI). A multi-region power accounting study of Proto-MPEX was performed utilizing expanded diagnostic measurements and improved modeling to identify mechanisms and locations of heat loss from the main plasma. Regions with lower power transport efficiencies have been identified. Power-to-target plate efficiencies have been calculated for a variety of plasma production scenarios: helicon power only, helicon power supplemented with electron cyclotron heating (ECH), helicon power supplemented with ion cyclotron heating (ICH), and helicon power supplemented with combined ECH and ICH. These efficiencies are extrapolated to MPEX relevant applied power sources in order to estimate the heat fluxes expected to be deposited to target plate surfaces for future steady-state PMI studies. Areas requiring further diagnostic measurements and modeling are identified.