Disruption Studies On C-MOD: Mitigation {\&} Hydrogen/Deuterium Fuel Recovery

Due to its high magnetic field, high plasma energy density and metallic first wall, the Alcator C-Mod tokamak provides a critical testbed for developing and testing disruption mitigation scenarios for ITER. We will report the first results using high-pressure gas injection of noble gases into C-Mod. These results will be compared to previous results from DIII-D, and possible implications for the penetration of gas jet impurities in ITER will be discussed. We also report on the successful demonstration of recovery of hydrogenic fuel by exploiting transient heating of the wall from planned disruptions, a technique proposed for ITER. Disruptions are shown to be effective at reducing the hydrogen/deuterium isotope ratio, as required for ion cyclotron H minority heating. The routine use of disruptions was successful at preventing net retention of fueled deuterium gas in the wall without detrimental effects to C-Mod operation, and thus shows initial promise for reducing tritium retention in ITER.