Ablation Simulation of Tungsten-Alternative Plasma-Facing Components due to Edge Localized Modes and Hard Disruptions

Innovative materials are investigated using a simulated electrothermal (ET) plasma to characterize erosion characteristics under ITER-relevant off-normal conditions. The tungsten alternatives investigated are mono-crystalline silicon carbides and MAX Phase ceramics. Preliminary code simulations using the ETFLOW plasma code are presented to assess erosive behavior in preparation for future experiments at ORNL’s electrothermal high heat flux experiment and the DiMES experiments for induced disruption on the DIII-D tokamak. Results indicate that erosion properties for SiC and two commercially available MAX Phases, Ti3SiC2 and Ti2AlC, compare well with tungsten and other ITER relevant components. A material-specific ablation constant, measured as total mass removed per incident heat flux per second, serves as a means for directly comparing erosion properties. Tungsten possesses the highest ablation constant value when compared to carbon, beryllium and the alternative materials α-6H SiC, Ti3SiC2, and Ti2AlC. The ablation thickness, calculated from the ablation constant and the specific density of the material, provides a comparison of surface thickness lost during a given off-normal event. Carbon (4.25 cm3/MJ) and tungsten (5.98 cm3/MJ) possess the lowest values. The alternative materials Ti3SiC2 (7.32 cm3/MJ) and α-6H SiC (8.44 cm3/MJ) exhibit the next best values, with Ti2AlC being the least effective (9.35 cm3/MJ). SiC shows the best vapor shielding efficiency of the three alternative materials, with Ti3SiC2 and Ti2AlC giving similar efficiencies. Taking into account vapor shielding effects using both opacity and fractional models, SiC exhibits the best ablation characteristics of the three materials in terms of thickness loss, with Ti3SiC2 giving similar results and overall appearing the superior of the two MAX Phases.