Journal of Fusion Energy

, Volume 38, Issue 1, pp 147–161 | Cite as

Progress in the Conceptual Design of the Helical Fusion Reactor FFHR-d1

  • Nagato YanagiEmail author
  • Takuya Goto
  • Junichi Miyazawa
  • Hitoshi Tamura
  • Yoshiro Terazaki
  • Satoshi Ito
  • Teruya Tanaka
  • Hidetoshi Hashizume
  • Akio Sagara
Original Research


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.


Helical 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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© Springer Science+Business Media, LLC, part of Springer Nature 2018

Authors and Affiliations

  1. 1.National Institute for Fusion ScienceTokiJapan
  2. 2.Department of Quantum Science and Energy Engineering, Graduate School of EngineeringTohoku UniversitySendaiJapan

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