Modeling of multistage disruption mitigation scenarios and runaway electrons with the DTRAN/CQL3D codes

Successful disruption mitigation in tokamaks includes safe quenching of plasma thermal energy (TQ), plasma current (CQ), and non-thermal/relativistic runaway electron (RE) fractions; that requires multistage mitigation scenarios (MMS) based on successive controlled mass injections (or RF waves, MHD events). For advanced modeling of such MMS, CompX is developing the integrated modeling package including: 1D multielement multispecies flux-surface-average plasma transport code DTRAN; atomic physics code CRAMD-RE; GSE magnetic equilibrium library EQLIB; and common CDC framework. The dynamics of velocity distribution functions (VDF) is simulated with kinetic 2V-1.5D Fokker-Planck code CQL3D+GENRAY. Here we present the DTRAN modeling results on SPI+MGI MMS for DIII-D leading to various low-temperature partially-ionized (LTPI) Ar-D-mixture plasma conditions at the end of CQ phase including RE-plateaus. The effects of a VDF RE-tail, anomalous transport, molecular chemistry (MAR, ICN, vibrational kinetics), line radiation (and the opacity), and evolving geometry on LTPI plasma performance are highlighted. Conditions for establishing a quasi-stationary VDF in RE-plateaus are discussed.