Mitigating plasma transient events using inert gas and pellet injections in ITER-like reactors

ITER-like and future commercial plants successful operation is critically determined by the effects of transient events on plasma facing components (PFCs) and nearby components. Transient plasma events like disruptions, ELMs, and runaway electrons can cause significant damage to these materials; seriously affecting the operations of these reactors. We upgraded and used our HEIGHTS comprehensive simulation package to predict ITER-like components response during these transient events. HEIGHTS integrate full 3D models starting from the lost hot core plasma particles through SOL, deposition on the divertor surface, and the resulting evolution and generation of a secondary mini-plasma of wall/divertor materials. Significant damage can result from a single event of a disruption or an ELM on most internal components including the reflector, dome structure, stainless steel tubes, and even parts of the first walls due to the high radiation power of the secondary generated plasma from the high-Z divertor materials (e.g., W). Potential mitigating solutions, such as neutral gas injection/puffing and pellet injections are presented with recent simulation results showing their pros and cons in mitigating the damage and if possible full mitigation is foreseen to this serious problem of transient plasma events. Preliminary results show that either pellet or sudden gas injections (airbag-like) may reduce damage upon careful choice of locations and gas density, however not totally preventing various damages to plasma facing components.