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The radiation response and the MHD destabilization during the thermal quenchafter a mixed species Shattered Pellet Injection (SPI) with impurity speciesneon and argon are investigated via 3D non-linear MHD simulation using theJOREK code. Both the $n=0$ global current profile contraction and the localhelical cooling at each rational surface caused by the pellet fragments arefound to be responsible for MHD destabilization after the injection.Significant current driven mode growth is observed as the fragments cross loworder rational surfaces, resulting in rapidly inward propagating stochasticmagnetic field, ultimately causing the core temperature collapse. The ThermalQuench (TQ) is triggered as the fragments arrive on the $q=1$ or $q=2$ surfacedepending on the exact $q$ profile and thus mode structure. When injecting froma single toroidal location, strong radiation asymmetry is found before andduring the TQ as a result of the unrelaxed impurity density profile along thefield line and asymmetric outward heat flux. Such asymmetry gradually relaxesover the course of the TQ, and is entirely eliminated by the end of it.Simulation results indicate that the aforementioned asymmetric radiationbehavior could be significantly mitigated by injection from toroidally oppositelocations, provided that the time delay between the two injectors is shorterthan $1ms$. It is also found that the MHD response are sensitive to therelative timing and injection configuration in these multiple injection cases.

Radiation asymmetry and MHD destabilization during the thermal quench after impurity Shattered Pellet Injection