ITER disruption mitigation technologies and beyond

ITER is designed to withstand a certain number of full scale plasma disruptions; each disruption event can induce excessive thermal loads, electromagnetic (EM) loads, and runaway electrons (REs) onto the vacuum vessel and in-vessel components. The consequences of unmitigated events are extremely serious in terms of reduced component lifetime and significant damage to the components. Disruption Mitigation System (DMS) is needed to inject a certain amount of particles into the disrupting plasma, preemptively within a very short time period or repetitively with a few milliseconds intervals. Ex-vessel (in port interspaces) Shattered Pellet Injection (SPI), which can work as a Massive Gas Injection (MGI) DMS without forming a pellet, has been down selected and considered as the baseline DMS technology through the nuclear phase operation. As a risk mitigation plan, MGI in one of the diagnostics port plugs in the neutral beam cell will be implemented for nonnuclear operation. Making the system compatible with the harsh environment in ITER port plugs and port cells is still a major design challenge. This paper presents the latest ITER DMS design, R&D status, and disruption mitigation research plans.