LHD-type reactor design studies

Collaboration work based on the LHD project has made great progress in design studies on the helical reactor FFHR. The main feature of FFHR is force-free-like configuration of helical coils, which simplifies the coil supporting structure with a high magnetic field instead of high plasma beta. The other feature is the selection of molten-salt Flibe as a self-cooling tritium breeder for the main reason of inherent safety. Encouraging positive results are shown on ignition access, mechanical stress in coils supporting structures, improvement in the blanket system including materials selection and tritium recovery. Critical issues and many subjects are mentioned as future work.