ELM control experiments in the KSTAR device

• Published in: Nuclear fusion Vol. 52; no. 11; pp. 114011 - 11
• Main Authors: Kim, Jayhyun, Jeon, Y.-M., Xiao, W.W., Yoon, S.-W., Park, J.-K., Yun, G.S., Ahn, J.-W., Kim, H.S., Yang, H.-L., Kim, H.K., Park, S., Jeong, J.H., Jung, M., Choe, G.H., Ko, W.H., Lee, S.-G., Nam, Y.U., Bak, J.G., Lee, K.D., Na, H.K., Hahn, S.-H., Diamond, P.H., Rhee, T., Kwon, J.M., Sabbagh, S.A., Park, Y.S., Park, H.K., Na, Y.S., Kim, W.C., Kwak, J.G.
• Format: Journal Article
• Language: English
• Published: IOP Publishing and International Atomic Energy Agency 01.11.2012
• Subjects: Coiling; Control systems; Devices; Elm; Heating; Molecular beams; Nuclear fusion; Perturbation methods
• ISSN: 0029-5515; 1741-4326
• DOI: 10.1088/0029-5515/52/11/114011

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 n 2 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 50 Hz 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.