OPTIMIZING THE THERMAL-CONDUCTIVITY OF VACUUM PLASMA-SPRAYED BERYLLIUM FOR FUSION APPLICATIONS

Plasma-spraying of beryllium is under investigation as a potential met hod for coating the first wall blanket surface of the International Th ermonuclear Experimental Reactor (ITER) and as a technique for regener ating damaged beryllium surfaces as a result of normal and off-normal operating events. Methods to optimize the thermal conductivity of vacu um plasma-sprayed (VPS) beryllium are currently under investigation at the Los Alamos National Laboratory's Beryllium Atomization and Therma l Spray Facility (BATSF). Studies are being conducted to evaluate the effect of the starting beryllium feedstock powder, processing paramete rs and resulting microstructures on the thermal conductivity of VPS be ryllium. The characteristic layered microstructure, typical of plasma- sprayed deposits, contains regions of incomplete bonding between indiv idual splat layers which can decrease the thermal conductivity through the thickness of the deposit. Impurities present in the starting bery llium feedstock powder can also influence the thermal conductivity of VPS beryllium by causing impurity striations throughout the thickness of the deposit.