Disruption and Runaway Electron Mitigation With MGI in DIII-D

Past and ongoing disruption mitigation studies in DIII-D employing massive gas injection (MGI) are reviewed and compared with theoretical expectations. Emphasis in the review will be placed on 1)~the gas hydrodynamic delivery considerations that determine the rate of impurity and electron delivery to the plasma edge, 2)~the role of MHD instability and internal reconnection in effecting edge-to-core mixing of the edge-deposited impurities, and 3)~assessment of the mechanism(s) whereby MGI mitigates divertor energy deposition, reduces halo current magnitude and asymmetry and avoids runaway electron production and/or Coulomb-avalanche multiplication. Selected considerations for application of DIII-D MGI results to ITER (wherein time scales for impurity delivery are relaxed relative to DIII-D and other present experiments) will also be addressed.