Superconducting Magnet System of Large Helical Device

The Large Helical Device is a superconducting toroidal device for the fusion research which has a maximum stored energy of 1.6 GJ (4 T at the plasma center). The LHD has l/m = 2/10 superconducting helical coils and three sets of poloidal coils. The plasma performance expected is equivalent to a Q value (fusion out put/heating power) from 0.1 to 0.3. Since the LHD plasma is currentless, it provides a useful and reliable data base for the steady-state operation without any danger of plasma current disruptions. Therefore, the superconductivity is a key technology in this project. Results of research and development for the superconducting (SC) magnet system of the LHD is reported.