量研学術機関リポジトリ「QST-Repository」は、国立研究開発法人 量子科学技術研究開発機構に所属する職員等が生み出した学術成果（学会誌発表論文、学会発表、研究開発報告書、特許等）を集積しインターネット上で広く公開するサービスです。 Welcome to QST-Repository where we accumulates and discloses the academic research results(Journal Publications, Conference presentation, Research and Development Report, Patent, etc.) of the members of National Institutes for Quantum and Radiological Science and Technology.
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In order to proceed the integrated plasma scenario modeling of JA DEMO, (i) core transport simulation, (ii) vertical stability and (iii) MHD stability analyses have been performed. In addition, applicability of no/small ELM regimes to JA DEMO has also been investigated.
On the 1.5-D time-dependent core transport simulation by integrated code TOPICS, the steady-state operation condition with HH = 1.41, betaN = 3.6, fBS = 0.69 is demonstrated by optimizing the heating scenario, where CDBM transport model is used. It is also demonstrated that off-axis ECCD has important roles for maintaining the internal transport barriers (ITBs) for steady-state condition and for controlling the fusion power by control of ITB location. On the vertical stability analysis, the ramp-up scenario of high elongated plasma has been developed by using the plasma equilibrium simulator MECS with 3D eddy current effects. The temporal evolutions of the poloidal beta and internal inductance are evaluated using TOPICS. The result indicates that plasma elongation at 95% of poloidal flux of 1.75 is achievable in JA DEMO. Regarding the MHD stability analysis, the beta limit of JA DEMO plasma has been evaluated by using the linear ideal MHD stability code MARG2D. The beta limit without conducting wall is betaN ~ 2.6, while that with conducting wall can be improved to ~3.5 at the wall radius of rW/a = 1.35. Further improvements are observed with decreasing the wall radius, for example betaN ~ 3.9 at rW/a = 1.30.
It is important to investigate the applicability of no/small ELM regimes to a DEMO. The candidates of the no/small ELM regimes realized in the low collisionality region are grassy ELMy H mode and QH mode, which are observed in many tokamak experiments. The grassy ELM regime can be reduced the ELM energy to ~1% of the pedestal energy. The necessary conditions are the high poloidal beta ~1.4, the high safety factor q95>4, the high triangularity >0.4 and the low elongation <1.45. The DEMO main parameters, that satisfy the necessary conditions of grassy ELMy H mode, will be discussed.
Plasma Scenario Modeling for JA DEMO
