Role of fast-ion transport manipulating safety factor profile in KSTAR early diverting discharges
- National Fusion Research Inst., Daejeon (Korea)
- Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
- General Atomics, San Diego, CA (United States)
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Magnetohydrodynamics (MHD) activity is analyzed for a particular KSTAR discharge category, the main features of which are a high-$$q_\mathrm{min}$$ and a broad q profile. An interesting finding in this scenario is that a steady-state high-$$q_\mathrm{min}$$ and broad q profile has been constructed even without a strong off-axis current drive scheme. Time traces of magnetics spectrograms and electron cyclotron emission imaging (ECEI) clearly show that Alfvénic type MHD activity appears as a high-$$q_\mathrm{min}$$ and broad q profile is formed. Conversely, this activity disappears as the current profiles evolve toward a low-$$q_\mathrm{min}$$ profile. In this study, the effect of MHD modes and accompanying fast-particle transport on the formation of various current profiles is explored. The frequency patterns of the magnetics spectrograms and ECEI coherence are compared using a NOVA analysis to determine which series of Alfvénic modes are active. Then, the kick-model is applied to potential modes, and used to estimate how much fast-ions are transported and beam driven current profiles are varied. Here, by comparing the reconstructed total current profile from the kinetic EFIT with the beam-driven current profile estimated from the kick model, it is determined how energetic particle transport is responsible for maintaining the safety factor profile and which q profile can provide high βN operation.
- Research Organization:
- Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
- Sponsoring Organization:
- Ministry of Science and ICT
- Grant/Contract Number:
- AC02-09CH11466
- OSTI ID:
- 1814845
- Journal Information:
- Nuclear Fusion, Vol. 60, Issue 12; ISSN 0029-5515
- Publisher:
- IOP ScienceCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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