Modeling of plasma current decay during disruptions caused by massive impurity injection

Owaki, Hirokazu*; Sugihara, Masayoshi; Hatayama, Akiyoshi*

A numerical model is developed to evaluate the decay time of the plasma current during the disruption following intense impurity injections. Our model is based on the power balance equation between the joule heating and impurity radiation to evaluate the electron temperature and charge state after the thermal quench. The model is applied to the experimental results of massive N gas injections in JFT-2M, which simulate the "ingress-of-coolant event" as well as disruption mitigations in ITER. It is confirmed that the model can reproduce the experiments reasonably well.