Overview of Recent Japanese Activities in Fusion Technology

After the ITER/EDA study, Japanese activities in fusion technology have been mainly devoted to DEMO reactors. The paper intends to overview these activities.

With respect to the test blanket modules, solid breeder blankets with ferritic steel structure cooled by helium and water are being developed by JAERI in cooperation with universities and NIFS. Advanced blankets are being developed by universities and NIFS. In the area of tritium processing technology, R&D has been focused on the blanket tritium recovery technology. In terms of the superconducting magnet, JAERI has performed basic research for the Fusion Power Demonstration Plant, aiming at realization of toroidal filed higher than 13 T using innovative superconductors, such as Nb₃Al and High Temperature Superconductors (HTS). In the R&D of negative ion based NBI technologies, a H^- beam of 110 mA has been stably accelerated up to 0.9 MeV, which corresponds to the current density of 80 A/m². A beam power of 13.1 MW at 180 keV has been injected from three injectors in the LHD N-NBI. With respect to the radio-frequency heating technology, development of 170GHz ITER gyrotron has been progressed to achieve a 500kW for 100 sec operation in JAERI. Long pulse injection for 766 sec with 72 kW at 84 GHz was achieved in a LHD ECH experiment.