1 FIP / 2-5 Rb Progress in long pulse production of powerful negative ion beams for JT-60 SA and ITER

Significant progress in the extension of pulse durations of the powerful negative ion beams has been made to realize the neutral beams injectors for JT-60SA and ITER. As for the long pulse production of high-current negative ions for JT-60SA ion source, the pulse durations have been successfully increased from 30 s at 13 A on JT-60U to 100 s at 15 A by modifying the JT-60SA ion source, which satisfies 70% of the rated beam current for JT-60SA. This progress is based on the R&D efforts about the temperature control of the plasma grid and uniform negative ion productions with the modified tent-shaped filter field configuration. As for the long pulse acceleration of high power density beams in the MeV accelerator for ITER, the pulse duration of MeV-class negative ion beams has been extended by more than 2 order of magnitude from the last IAEA conference. A long pulse acceleration of 60 s has been achieved at 70 MW/m (683 keV, 100 A/m) by modifying the extraction grid with high cooling capability and high-transmission of negative ions. These results are the longest pulse durations of high-current and high-power-density negative ion beams in the world.