Post-disruption outgassing in Tore Supra

Abstract

Disruptive plasma termination was proposed for controlling long-term fuel retention because the subsequent increase of the post-discharge outgassing could help in minimizing the fuel stored in the vessel after each discharge. The efficiency of this method is investigated by analyzing the Tore Supra database for the period 2004–2010 (450 disruptions). Results are shown for the plasma motion during the current quench and the heating of deposits at the Toroidal Pumped Limiter surface. Dependences of the outgassing with internal and magnetic energy contents, increment of the wall inventory and cumulated time between two disruptions are characterized. It is shown: (1) that the desorbed gas originates from D-rich deposits close to the plasma when those located in remote areas are weakly affected and (2) that the amount of released gas saturates with discharge duration and time delay between two disruptions, which limits the efficiency of the method for long discharge operation. However, due to the larger volume/surface ratio, the efficiency of the method is expected to increase with the size of the device.