Abstract
Locked mode disruptions with a controlled toroidal phase are produced in the DIII-D tokamak by locking to large non-axisymmetric applied magnetic perturbations with different toroidal phases. The disruption conducted heat loads are found to reach almost completely the divertor region, possibly due to not only strong inner leg detachment but also plasma motion and limiting on the outer divertor leg shelf. The outer leg conducted heat loads are found to have a significant toroidal variation of order ±30%, with a dominant n = 1 structure. The heat load phase is shifted from the initial locked mode phase in a way that is approximately consistent with heat loss into the scrape-off layer being enhanced at the mode island O-point outer midplane crossing. These measurements suggest that pre-existing locked modes can affect the conducted heat load structure during the thermal quench by affecting the thermal quench MHD phase. This is consistent with previous MHD simulations which indicated that pre-disruption locked mode structures can persist and survive to some degree through the large thermal quench MHD. This work complements previous work [Shiraki et al., Nucl. Fusion 55, 073029 (2015)] which showed that n = 1 structures in mitigated disruptions can create toroidal variations in the disruption radiated power.
Original language | English |
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Article number | 102502 |
Journal | Physics of Plasmas |
Volume | 25 |
Issue number | 10 |
DOIs | |
State | Published - Oct 1 2018 |
Funding
Permission to use the SLCONTOUR magnetic probe analysis routine by E. J. Strait is gratefully acknowledged. Initial magnetic data analysis by M. Okamoto is gratefully acknowledged. The valuable technical support of the DIII-D team is gratefully acknowledged. This work was supported in part by the U. S. Department of Energy under DE-FG02-07ER54917 and DE-FC02-04ER54698. DIII-D data shown in this paper can be obtained in digital format by following the links at https://fusion.gat.com/global/D3D_DMP.