Analysis of Disruption Scenarios and Their Possible Mitigation in ITER
Database analyses have been carried out to derive physics guidelines for the shortest current quench time and their waveforms as well as the product of halo fraction with toroidal peaking factor arising from disruptions in ITER. Several representative disruption scenarios are specified. Disruption simulations with the DINA code and ElectroMagnetic load (EM) analyses with 3D Finite Element Method (FEM) code are performed for these scenarios. Reasonable margins are confirmed in the forces on in-vessel components due to induced eddy and halo currents for these representative scenarios. It is noted that an increase in the current decay time by a factor of 1.5-2 can reduce the force due to eddy currents significantly at the expense of small increase of halo currents. This condition can be realized by injection of (1-2)x1024 atoms of neon without generating runaway electrons. In the massive injection scheme, the response time can be very fast, and the mitigation for only a small fraction of the total number of disruptions ( (3-4)%) is missed, while the force on the gas inlet valve becomes high (300kg). In the moderate injection case, the response time is rather slow (100ms) and the mitigation for a substantial fraction of the total number of disruptions (40-50)% is missed, while the force on the inlet valve can be easily handled.