Radiated power measurement during the thermal quench phase of a density limit disruption

Abstract

Radiated power measurements taken during the thermal quench of a density limit disruption in the DIII-D tokamak [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] demonstrate that ten times more power is radiated from the main chamber than is deposited into the divertor floor. This contrasts with the standard picture of the thermal quench of disruptions, where energy is lost along open field lines into the divertor. The observed radiation appears to result from a sudden increase in deuterium outgassing and carbon impurity release from the main chamber walls. The impurities and the associated cold front are observed to mix into the plasma core at a rate about 100 times larger than standard (H-mode) particle diffusion rates. Comparison with other types of disruptions in DIII-D suggests that plasma–main wall interactions may play an important role in the thermal quench of many disruptions.