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ELM control experiments in the KSTAR device

  • Author(s): Kim, J
  • Jeon, YM
  • Xiao, WW
  • Yoon, SW
  • Park, JK
  • Yun, GS
  • Ahn, JW
  • Kim, HS
  • Yang, HL
  • Kim, HK
  • Park, S
  • Jeong, JH
  • Jung, M
  • Choe, GH
  • Ko, WH
  • Lee, SG
  • Nam, YU
  • Bak, JG
  • Lee, KD
  • Na, HK
  • Hahn, SH
  • Diamond, PH
  • Rhee, T
  • Kwon, JM
  • Sabbagh, SA
  • Park, YS
  • Park, HK
  • Na, YS
  • Kim, WC
  • Kwak, JG
  • et al.
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. © 2012 IAEA, Vienna.

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