Gas jet disruption mitigation studies on Alcator C-Mod and DIII-D
Author(s)
Hollmann, E. M.; Whyte, D. G.; Antar, G. Y.; Bakhtiari, M.; Boedo, J. A.; Evans, T. E.; Jernigan, T. C.; Gray, D. S.; Groth, M.; Humphreys, D. A.; Lasnier, C. J.; Moyer, R. A.; Parks, P. B; Rudakov, D. L.; Strait, E. J.; Wesley, J.; West, W. P.; Wurden, G.; Yu, J.; Granetz, Robert S.; Izzo, Viviana A.; Bader, Aaron Craig; Biewer, T.; Hutchinson, Ian H.; Reinke, Matthew Logan; Terry, James L; Hutchinson, Ian Horner; ... Show more Show less
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High-pressure noble gas jet injection is a mitigation technique which potentially satisfies the requirements of fast response time and reliability, without degrading subsequent discharges. Previously reported gas jet experiments on DIII-D showed good success at reducing deleterious disruption effects. In this paper, results of recent gas jet disruption mitigation experiments on Alcator C-Mod and DIII-D are reported. Jointly, these experiments have greatly improved the understanding of gas jet dynamics and the processes involved in mitigating disruption effects. In both machines, the sequence of events following gas injection is observed to be quite similar: the jet neutrals stop near the plasma edge, the edge temperature collapses and large MHD modes are quickly destabilized, mixing the hot plasma core with the edge impurity ions and radiating away the plasma thermal energy. High radiated power fractions are achieved, thus reducing the conducted heat loads to the chamber walls and divertor. A significant (2 × or more) reduction in halo current is also observed. Runaway electron generation is small or absent. These similar results in two quite different tokamaks are encouraging for the applicability of this disruption mitigation technique to ITER.
Date issued
2007-08Department
Massachusetts Institute of Technology. Department of Nuclear Science and Engineering; Massachusetts Institute of Technology. Plasma Science and Fusion CenterJournal
Nuclear Fusion
Publisher
Institute of Physics Publishing
Citation
R.S. Granetz et al 2007 Nucl. Fusion 47 1086 doi: 10.1088/0029-5515/47/9/003 © IOP Publishing 2007
Version: Author's final manuscript
ISSN
0029-5515
1741-4326