ITER DMS fast shutter prototype testing

The Disruption Mitigation System (DMS) employed by ITER uses shattered pellet injection, wherein a large cryogenic ice pellet is accelerated by high pressure gas and shattered just before entering the plasma. This results in a cloud of smaller pellet fragments. This results in a cloud of smaller pellet fragments. The propellant gas can reach the plasma prematurely, potentially triggering an early disruption before the main material from the shattered pellet arrives, thus compromising mitigation efficiency. The primary strategy for propellant gas retention is the utilization of a gas suppressor chamber. However, as a backup measure in case the suppressor chamber is insufficient, each injector can be equipped with a Fast Shutter to block the propellant gas path. The Fast Shutter Prototype has been developed at the HUN-REN Centre for Energy Research, Budapest, Hungary, as part of the DMS design development by the ITER Organization. Testing demonstrated that the ITER DMS requirements were met in terms of cycle number before failure, leak rate, and closing time repeatability. This contribution summarizes the laboratory test results and the modelling validation efforts.