168. EROSION OF AL IN DIII-D TOKAMAK DIVERTOR AND PISCES-B LINEAR PLASMAS
Name: Christopher Chrobak
Grad Year: 2017
Future high power fusion devices which intend to use a primarily low-Z first wall may be limited by the high net erosion rate and long range material migration expected of these materials. In an effort to provide a benchmark for modeling codes used to design and predict the lifetime of tokamak first wall components, we have made measurements of erosion, ionization, and redeposition of Al, a low-Z material, in separate helium and deuterium low power, low density L-mode plasmas at the outer divertor strike point of DIII-D. Supporting experiments were performed exposing Al to He and D plasmas in the UCSD PISCES-B linear plasma device to measure the erosion rate and spectroscopic emission coefficients. Al was selected as a non-hazardous proxy material for beryllium, the primary ITER first wall material, owing to its similar oxide and hydride chemistry, uniqueness from DIII-D background sources, and long ionization mean free path compared to ion gyro radius typical of low-Z materials. In this study we have also examined the effect of surface roughness on the erosion and redeposition behavior, and estimated the amount of Al erosion caused by the intrinsic background plasma carbon impurity.
Industry Application Area(s)
Energy/Clean technology | Materials