Validation of density pump-out by pedestal-foot magnetic island formation prior to ELM suppression in KSTAR and DIII-D tokamaks

Nuclear Fushion

article

Q.M. Hu¹  J.-K. Park¹  S.M. Yang¹  S.K. Kim¹  N.C. Logan²  R. Nazikian³  J. Kang⁴  C. Paz-Soldan⁵  W.H. Ko⁴  G.Y. Park⁴ 

[1] Princeton Plasma Physics Laboratory, Princeton;Lawrence Livermore National Laboratory;General Atomics;Korea Institute of Fusion Energy;Columbia University

关键词: divertor;    lithium;    vapor box;    detachment;    SOLPS-ITER;    NSTX-U;    closure;   

DOI  :  10.1088/1741-4326/ace5c0

来源: Institute of Physics Publishing Ltd.

【 摘 要 】

TM1 nonlinear two-fluid simulations reveal key characteristics of density pump-out caused by pedestal-foot island formation when applying resonant magnetic perturbation (RMP). These characteristics include a bifurcation in pump-out with a low RMP coil current threshold, a sensitivity of pump-out magnitude toq ₉₅, and the magnitude of pump-out scaling as the square root of the RMP coil current. Dedicated experiments are carried out in the KSTAR and DIII-D tokamaks to validate these features and show that: (1) a staircase bifurcation in density pump-out is observed when slowly ramping up then= 1 RMP current, and the density fluctuations are found to be slightly decreased from the pedestal-foot to the pedestal-top; (2) the magnitude of density pump-out becomes weaker when decreasingq ₉₅ from 5.5 to 4.9, and a partial recovery of density pump-out is observed whenq ₉₅ is ramped down to lower than 4.9; and (3) analysis of a DIII-D database ofn= 3 RMP edge-localized mode control experiments finds that the magnitude of density pump-out is proportional to the square root of RMP coil current Δ n _e/ n _e ∝ I_{{ext{RMP}}}^{,0.5} . These experimental observations are consistent with TM1 simulations.

【 授权许可】

Unknown