Magnet Design Considerations for Fusion Nuclear Science Facility

Authors:  Y. Zhai, C. Kessel, L. El-guebaly and P. Titus

Abstract: The Fusion Nuclear Science Facility (FNSF) is the first strongly fusion nuclear confinement facility to provide an integrated fusion environment with fully integrated components to bridge the technical gaps of fusion plasma and fusion nuclear science between ITER and the demonstration power plant (DEMO). Compared to ITER, the FNSF is smaller in size but generates much higher magnetic field, 30 times higher neutron fluence with 3 orders of magnitude longer plasma operation at higher operating temperatures for structures surrounding the plasma. Input parameters to the magnet design from system code analysis include magnetic field of 7.5 T at the plasma center with plasma major radius of 4.8 m and minor radius of 1.2 m, and a peak field of 15.5 T on the TF coils for FNSF. Both lower temperature superconductor (LTS) and high temperature superconductor (HTS) are considered for the FNSF magnet design based on the state-of-the-art fusion magnet technology.  The higher magnetic field can be achieved by using the high performance ternary Restack Rod Process (RRP) Nb3Sn strands for toroidal field (TF) magnets. The circular cable-in-conduit conductor (CICC) design similar to ITER magnets and a high aspect ratio rectangular CICC design are evaluated for FNSF magnets but low activation jacket materials may need to be selected. The conductor design concept and TF coil winding pack composition and dimension based on the horizontal maintenance schemes are discussed. Neutron radiation limits for the LTS and HTS superconductors and electrical insulation materials are also reviewed based on the available materials previously tested. The material radiation limits for FNSF magnets are defined as part of the conceptual design studies for FNSF magnets.

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Presented at: 24th International Conference on Magnet Technology, COEX, Seoul, Korea, October 2015

Published in:  IEEE Transactions on Applied Superconductivity
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Download PPPL-5206 (pdf 5.4 MB 7 pp)
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