Progress in the Conceptual Design of the Helical Fusion Reactor FFHR-d1
The LHD-type helical fusion reactor FFHR has been studied to realize steady-state fusion power generation without a need for current drive and free from disruption. The conceptual design studies of FFHR are steadfastly progressing based on the presently ongoing experiments in the Large Helical Device (LHD). In order to enhance the attractive features of the base option of FFHR-d1A, which is similar to LHD, configuration optimization is being considered for FFHR-d1C. Slight modification of the helical coil trajectory gives an improved condition both for the plasma confinement and the MHD stability. In order to overcome the difficulty for construction and maintenance associated with the three-dimensional structure, innovative ideas are being explored for the superconducting magnet, divertor, and blanket. For the superconducting helical coils, the joint-winding method confirms a fast manufacturing process. The helical divertor is reexamined and practical feasibility is discussed. The maintenance method of the helical divertor and the helically-segmented breeder blanket is a serious issue and a plausible solution is proposed.
KeywordsHelical fusion reactor FFHR Heliotron Configuration optimization High-temperature superconductor Helical divertor Blanket maintenance Aquarium method
The authors thank the members of the Fusion Engineering Research Project at NIFS, especially, T. Mito, S. Hamaguchi, S. Imagawa, K. Takahata, A. Iwamoto, T. Obana, H. Chikaraishi, N. Ashikawa, M. Tokitani, G. Kawamura, Y. Hamaji, R. Sakamoto, and S. Masuzaki for fruitful discussions. Special thanks are given to T. Muroga and H. Yamada. One of the authors (N. Y.) is grateful for the continuous discussion and encouragement given by A. Komori regarding the feasibility of the helical divertor. The optimized configuration provided by S. Okamura is highly appreciated. The NITA coil configuration was proposed by the late T. Watanabe, who made tremendous contributions to the FFHR design activities. The design of the helical divertor and the helically-segmented blanket made by S. Kinoshita at Hitachi Ltd. are greatly acknowledged. This work was supported in part by the Japan Society for the Promotion of Science (JSPS) Grant-in-Aid for Scientific Research (S) under Grant 26220913.
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