Speaker
Dr
Atsushi Kojima
(Japan Atomic Energy Agency)
Description
The long pulse generation of the powerful negative ion beams of 500 keV, 22 A (130 A/m^2) and 1MeV, 40 A (200 A/m^2) is the essential challenge to realize the negative-ion-based neutral beam injectors (NBIs) for JT-60SA and ITER, where 10 MW D0 beam for 100 s and a 16.5 MW for 3600 s are designed, respectively. In Japan Atomic Energy Agency (JAEA), after the achievements of the beam current density and energy required for JT-60SA and ITER with a short pulse duration, the target of R&D is focused on the extension of the pulse duration in JT-60 negative ion source and the MeV accelerator.
Significant progress in the extension of pulse duration of the powerful negative ion beams has been made to realize the neutral beams injectors for JT-60SA and ITER. The pulse duration and the current density of the JT-60 negative ion source has been successfully improved from 30 s at 80 A/m^2 in the previous operation to 100 s at 120-130 A/m^2, which satisfy the rated values for JT-60SA. This progress has been achieved by controlling the negative ion production via the surface temperature of the plasma grid. The pulse duration of the MeV class negative ion beams for ITER has been also extended by more than an order of magnitude in the MeV accelerator. A long pulse acceleration of 8.7 s has been achieved at 880 keV, 130 A/m^2 by improving the cooling capability of the extraction grid where the aperture displacement for the beamlet steering is also modified, so there is no limitation to increase the power density and the pulse duration. This is the longest pulse duration of the MeV-class negative ion beams in the world.
| Country or International Organisation | Japan |
|---|---|
| Paper Number | FIP/2-5Rb |
Primary author
Dr
Atsushi Kojima
(Japan Atomic Energy Agency)
Co-authors
Mr
Haruhiko Yamanaka
(Japan Atomic Energy Agency)
Dr
Hiroyuki Tobari
(Japan Atomic Energy Agency)
Mr
Kazuhiko Mogaki
(Japan Atomic Energy Agency)
Dr
Kazuhiro Watanabe
(Japan Atomic Energy Agency)
Dr
Kazumi Ohasa
(Japan Atomic Energy Agency)
Dr
Larry Grisham
(Princeton Plasma Physics Laboratory)
Dr
Masafumi Yoshida
(Japan Atomic Energy Agency)
Mr
Masao Komata
(Japan Atomic Energy Agency)
Mr
Masaya Hanada
(Japan Atomic Energy Agency)
Mr
Masayuki Dairaku
(Japan Atomic Energy Agency)
Dr
Mieko Kashiwagi
(Japan Atomic Energy Agency)
Dr
Naotaka Umeda
(Japan Atomic Energy Agency)
Mr
Noboru Akino
(Japan Atomic Energy Agency)
Mr
Norikatsu Seki
(Japan Atomic Energy Agency)
Mr
Shuji Nemoto
(Japan Atomic Energy Agency)
Mr
Shunichi Sasaki
(Japan Atomic Energy Agency)
Mr
Tatsuo Shimizu
(Japan Atomic Energy Agency)
Mr
Yasuei Endo
(Japan Atomic Energy Agency)
