Assessment of massive gas injection as a disruption mitigation tool in Tore Supra

19th International Conference on Plasma-Surface Interactions in Controlled Fusion Devices (PSI), Univ Calif, Gen Atom, San Diego, CA, MAY 24-28, 2010International audienceMassive gas injection was used on Tore Supra to study disruption mitigation. The cooling time between the injection and the thermal quench drops to 2 ms for larger gas flow rates (similar to 5e24 atoms/s) limiting the radiated energy to similar to 10% of the plasma thermal energy content. A significant reduction of the heat load on the limiter is nevertheless observed in the mitigated cases. The broadening factor of the power decay length in the scrape-off layer during the thermal quench estimated around 10 (+/-5) does not change significantly between mitigated and unmitigated. Reached densities with He injections are sufficient to suppress primary runaway electrons (dominant on Tore Supra) but still far too low to avoid avalanche process (dominant in ITER). The extension of the current quench time, which is observed in mitigated disruptions (typically by 50%), could be an attractive feature to reduce the requirements on the density. (C) 2011 Elsevier B.V. All rights reserved