Application of HTSC coils for mitigation of VDE during a major disruption

The authors proposed the new method to control plasma position passively with use of high Tc superconducting coils (HTSCs). HTSCs are robust against the thermal disturbance, so that they can be installed in the vicinity of plasmas. In this study, we examine that the VDEs during disruptions can be mitigated or not by using HTSC coils as a stabilizer. Shape and profile of plasmas will change considerably during a disruption, so that the linearized model cannot be applied to this problem. Tokamak Simulation Code (TSC) is employed to evaluate the stabilizing effect of HTSC during a major disruption. The configuration of International Thermonuclear Experimental Reactor (ITER) is taken as an example for numerical analyses. The result of simulations using linear model agreed with that of TSC computation. The results of the simulation show that VDEs during disruptions are mitigated due to the stabilizing effect of HTSC. The vertical instability growth rate is improved if HTSC coils are installed on the backplate. The electromagnetic forces on HTSCs during a disruption were also estimated. A design to accommodate these forces is possible without any difficulty. (author)