Mass loss, sublimation, and surface damage of lanthanum hexaboride in an arc jet plasma.

An experimental and simulation-based approach is used to determine the effects of an arc jet plasma on the refractory ceramic material lanthanum hexaboride ( LaB 6). Experiments are performed at the High Energy Flux Test facilitY (HEFTY) located at UCLA. An SG-100 plasma jet generates an argon plasma into a vacuum chamber and imparts a maximum heat flux of 19.5 MW/ m 2 onto LaB 6 disks. Heat flux results are calibrated using a combination of thermocouple data as well as multiphysics numerical simulations in COMSOL, which aim to replicate the testing environment. Moreover, material characterization tools including scanning electron microscopy, energy-dispersive x-ray spectroscopy, x-ray diffraction, and optical profilometry are used to better understand the mechanisms by which LaB 6 loses mass through evaporation, sublimation, and surface damage during an arc jet exposure. It is determined that a minimum energy fluence of 200–300 MJ/ m 2 produces a consistent LaB 6 melt pool and that an incident heat flux of 19.5 MW/ m 2 results in a 0.11 mm/s surface recession rate. [ABSTRACT FROM AUTHOR]