Mitigating severe damages to divertor and nearby components during plasma transients in ITER-like reactors*

Successful operation of thermonuclear reactors such as ITER, DEMO, and future commercial plants is critically determined by the choice of materials for various components. We comprehensively simulate the entire tokamak with exact 3D geometry to predict various materials with innovative designs to predict future ITER-like and DEMO performances during plasma instabilities. We used our HEIGHTS simulation package to predict ITER-like components response during transient events. HEIGHTS integrate 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 plasma of divertor materials. The simulation showed significant reduction in the heat loading and damage to all the divertor nearby and internal components in the case when lithium is used on the divertor plates compared to the case when either tungsten or carbon are used on the divertor plate. Significant damage can occur on the reflector, Dome structure, stainless steel tubes, and even parts of the first walls due to the high radiation power of the secondary plasma generated from high-Z divertor materials. Photon radiation deposition into the divertor and nearby components was decreased by two order of magnitude. This analysis showed that using liquid lithium on top or small C strip embedded in W can lead to substantial mitigation of transient events and significant enhancement in components lifetime. Comments of neutral gas injection pros and cons to mitigate transient events will also be addressed