Analysis of Propellant Gas Suppression in Shattered Pellet Injector System of the ITER Experiment

Abstract Plasma disruptions in tokamak fusion reactors like ITER threaten reactor equipment. To mitigate these events, a Shattered Pellet Injector (SPI) system using cryogenic solid pellets propelled by high-pressure gas was developed at the HUN-REN Centre for Energy Research. A suppressor system, consisting of multiple chambers and separators, was designed to capture the expelled gas. Computational Fluid Dynamics (CFD) simulations and experimental pressure measurements revealed that while CFD accurately predicts pressure peaks in the suppressor compartments, it struggles with gas expansion velocity. Experimental tests show gaps and leaks significantly influence pressure evolution. Findings indicate the suppressor retains some propellant gas but loses efficiency without a pellet. These insights help to develop disruption mitigation strategies for ITER.