Demonstration of sawtooth period control with EC waves in KSTAR plasma

Journal Article · Thu Mar 12 00:00:00 EDT 2015 · EPJ Web of Conferences

DOI:https://doi.org/10.1051/epjconf/20158702016· OSTI ID:1214574

Jeong, J. H. ^[1]; Bae, Y. S. ^[1]; Joung, M. ^[1]; Kim, D. ^[2]; Goodman, T. P. ^[2]; Sauter, O. ^[2]; Sakamoto, K. ^[3]; Kajiwara, K. ^[3]; Oda, Y. ^[3]; Kwak, J. G. ^[1]; Namkung, W. ^[4]; Cho, M. H. ^[4]; Park, H. ^[5]; Hosea, J. ^[6]; Ellis, R. ^[6]

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1. National Fusion Research Institute, Daejeon (Korea)
2. Ecole Polytechnique Federale de Lausanne (EPFL), Lausanne (Switzerland)
3. Japan Atomic Energy Agency, Naka (Japan)
4. POSTECH, Pohang (Korea)
5. UNIST, Ulsan (Korea)
6. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)

The sawtooth period control in tokamak is important issue in recent years because the sawtooth crash can trigger TM/NTM instabilities and drive plasmas unstable. The control of sawtooth period by the modification of local current profile near the q=1 surface using ECCD has been demonstrated in a number of tokamaks [1, 2] including KSTAR. As a result, developing techniques to control the sawtooth period as a way of controlling the onset of NTM has been an important area of research in recent years [3]. In 2012 KSTAR plasma campaign, the sawtooth period control is carried out by the different deposition position of EC waves across the q=1 surface. The sawtooth period is shortened by on-axis co-ECCD (destabilization), and the stabilization of the sawtooth is also observed by off-axis co-ECCD at outside q=1 surface. In 2013 KSTAR plasma campaign, the sawtooth locking experiment with periodic forcing of 170 GHz EC wave is carried out to control the sawtooth period. The optimal target position which lengthens the sawtooth period is investigated by performing a scan of EC beam deposition position nearby q=1 surface at the toroidal magnetic field of 2.9 T and plasma current of 0.7 MA. The sawtooth locking by the modulated EC beam is successfully demonstrated as in [3-5] with the scan of modulation-frequency and duty-ratio at the low beta (β_N~0.5) plasma. In this paper, the sawteeth behavior by the location of EC beam and the preliminary result of the sawtooth locking experiments in KSTAR will be presented.

• Research Organization: Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
• Sponsoring Organization: USDOE
• Grant/Contract Number: AC02-09CH11466
• OSTI ID: 1214574
• Journal Information: EPJ Web of Conferences, Vol. 87; ISSN 2100-014X
• Publisher: EDP Sciences
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY