Impact of edge-localized resonant magnetic perturbation on L-H transition in the KSTAR tokamak
arXiv:2611.16846
Y. Zhang, M. Jiang, K. X. Han, W. H. Ko, S. M. Yang, J. D. Hu, Z. B. Guo, M. J. Choi, J. W. Juhn, J. Lee, J. H. Lee, Y. H. Lee, Y. F. Liu, X. B. Li, Y. R. Zhu, G. Q. Dong, G. Z. Hao
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On the KSTAR tokamak, an edge-localized resonant magnetic perturbation kept the plasma from entering high-confinement mode. The edge flow shear fell below the level that normally quiets the turbulence.
Read free explainer →The impact of edge-localized resonant magnetic perturbation (ERMP) on the low-to-high (L-H) confinement mode transition is investigated through dedicated experiments on the KSTAR tokamak with tungsten divertor and numerical simulations with a one-dimensional (1D) reduced transport model. Experimentally, under matched conditions, the ERMP inhibits the L-H transition, whereas the reference discharge without ERMP enters H-mode. The ERMP enhances edge electron temperature fluctuations and the turbulence decorrelation rate, and flattens the toroidal rotation, reducing the edge $E\times B$ velocity shear below the threshold required for turbulence suppression. An extended 1D predator-prey model, which incorporates toroidal flow evolution and realistic radial profile of the magnetic perturbation due to plasma response field, reproduces the experimental trends of enhanced turbulence, reduced ExB flow shear, and inhibited L-H transition. These findings contribute to a better understanding of how ERMP affects L-H transition dynamics in tungsten divertor environments and offer a valuable reference for the application of ERMP in current and future fusion devices.