ELM control experiments in the KSTAR device

Jayhyun Kim, Y. M. Jeon, W. W. Xiao, S. W. Yoon, J. K. Park, G. S. Yun, J. W. Ahn, H. S. Kim, H. L. Yang, H. K. Kim, S. Park, J. H. Jeong, M. Jung, G. H. Choe, W. H. Ko, S. G. Lee, Y. U. Nam, J. G. Bak, K. D. Lee, H. K. NaS. H. Hahn, P. H. Diamond, T. Rhee, J. M. Kwon, S. A. Sabbagh, Y. S. Park, H. K. Park, Y. S. Na, W. C. Kim, J. G. Kwak

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45 Scopus citations

Abstract

The fourth KSTAR campaign in 2011 concentrated on active edge-localized mode (ELM) control by various methods such as non-axisymmetric magnetic perturbations, supersonic molecular beam injection (SMBI), vertical jogs of the plasma column and edge electron heating. The segmented in-vessel control coil (IVCC) system is capable of applying n2 perturbed field with different phasing among top, middle and bottom coils. Application of an n=1 perturbed field showed a desirable ELM suppression result. Fast vertical jogs of the plasma column achieved ELM pace-making and ELMs locked to 50Hz vertical jogs were observed with a high probability of phase locking. A newly installed SMBI system was used for ELM control and the state of mitigated ELMs was sustained by the optimized repetitive SMBI pulse for a few tens of ELM periods. A change in ELM behaviour was seen due to edge electron heating although the effect of ECH launch needs supplementary analyses. The ECEI images of suppressed/mitigated ELM states showed apparent differences when compared with natural ELMy states. Further analyses are ongoing to explain the observed ELM control results.

Original languageEnglish
Article number114011
JournalNuclear Fusion
Volume52
Issue number11
DOIs
StatePublished - Nov 2012

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