Transient thermal analysis for optimal armor material in upgraded mockup for PST using MOOSE Framework

Abstract The divertor mockup design for the Pakistan Spherical Tokamak (PST) needs several improvements. These include reducing the total number of upper and lower divertors to 32 and enhancing the heat load capacity to 1 MW/m 2 . This study involves a thermal analysis of the upgraded divertor design for PST through simulation using MOOSE Framework. The simulation involves two steps – validation and thermal analysis. Validation is achieved by modeling 1D and 2D conduction problems in MOOSE Framework and comparing the results with the analytical solutions. The thermal analysis of a mockup of the upgraded PST divertor configurations with tungsten and graphite as armor materials under peak thermal heat load conditions of 1 MW/m 2 is performed. The results of the transient thermal analysis reveal that the mockup surface temperature rise for tungsten remains lower than that for graphite. The findings of the study indicate that both tungsten and graphite mockups can sustain a specific heat flux of 1 MW/m 2 for up to 3 s. However, even being a good conductor of heat, tungsten’s high atomic number (Z) poses challenges in plasma stability. On the other hand, graphite when paired with an efficient cooling system for controlling surface temperature rise is a superior armor material due to its affordability, ease of availability, and better compatibility with plasma environments. It is recommended as the preferred armor material for the upgraded divertor mockup in the PST system.