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 Science and Technology.
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The method for reducing a magnetic flux consumption of a central
solenoid (CS) is investigated to reduce the size of CS in DEMO reactor. The
reduction of the CS flux consumption during a plasma current ramp-up phase by the electron cyclotron (EC) heating is investigated using an integrated modeling code suite, TOPICS. A strongly reversed shear q profile tend to be produced and the plasma might be disruptive if intense off-axis EC heating is applied. However, we find the optimum temperature profile corresponding to a weak shear q profile with which the resistive flux consumption is minimized. This optimum temperature profile is tried to be reproduced using 6 EC rays with 20 MW and the resistive flux consumption during the current ramp-up can be reduced by 63% from the estimation using the Ejima constant of 0.45. As a result of this reduction, the total flux consumption can be reduced by 20% from the conventional estimation. In addition, we find that the resistive flux consumption is closely related to the volume averaged electron temperature and not to the profile shape. Using this relation, the required heating power is estimated to be 31 MW based on a well established global confinement scaling, ITER L-89P. As a result, it is clarified that the CS flux consumption can be reduced by 20% even when a strongly reversed shear q profile is avoided using 20-31 MW of EC heating. This reduction of the flux consumption accounts for 10% reduction of the CS radius. It is also clarified that
the reduction of the CS flux consumption up to 25% is possible in general when the
temperature profile and the q profile is optimized.
Reduction of poloidal magnetic flux consumption during plasma current ramp-up in DEMO relevant plasma regimes
