Integration of Massive-Gas and Lithium-Pellet Injections for Disruption Mitigation in Experimental Advanced Superconducting Tokamak

A novel hybrid injector was developed by integrating the massive gas and lithium pellet injections to simultaneously cool down the core and boundary areas of plasma for disruption mitigation in Experimental Advanced Superconducting Tokamak (EAST).The prototyped hybrid injector was evaluated with the lab-built test platform.The preliminary results show that the newly-designed hybrid injector worked well for disruption mitigation because of more effective cooling down and mixing of plasma and impurities in larger volume including the core and boundaries.For example, as the injection pressure increased from 0.6 to 1.1 and to 1.5 MPa, the fastest speeds of the injected glass pellets were measured to be 250, 350 and 400 m/s, respectively.There will be still much room for Li-pellet acceleration due to its lighter density.The installation and on-line evaluation of the optimized hybrid injector in EAST were scheduled in 2018.