Author :
Kuriyama, M. ; Akino, N. ; Ebisawa, N. ; Grisham, L. ; Hikita, S. ; Honda, A. ; Itoh, T. ; Kawai, M. ; Kazawa, M. ; Kusaka, M. ; Mogaki, K. ; Nagase, N. ; Ohga, T. ; Okumura, Y. ; Oohara, H. ; Satoh, F. ; Seki, H. ; Tanai, Y. ; Toyokawa, Y. ; Umeda, N. ;
Author_Institution :
Naka Fusion Res. Establ., JAERI, Ibaraki, Japan
Abstract :
In the negative ion based NBI for JT-60, the maximum injection power reached so far is 5.2 MW at 350 keV. However the beam power and pulse duration are limited mainly by a mismatched perveance of the accelerated beam due to the source plasma non-uniformity. The source plasma uniformity was investigated by measuring the arc current distribution and ion saturation current in the plasma generator. A large non-uniformity has been found at the bottom side along a longitudinal direction in the ion source. As countermeasures against the source plasma non-uniformity, the adjustment of resistors in series with are current circuit connected to each of eight filament groups and the masking both fringes of the plasma grid are effective
Keywords :
Tokamak devices; fusion reactor design; plasma beam injection heating; 350 keV; 5.2 MW; JT-60U; arc current distribution; beam power; ion saturation current; negative ion based NBI; negative ion based neutral beam injection; Acceleration; Circuits; Current distribution; Current measurement; Ion sources; Particle beams; Plasma accelerators; Plasma measurements; Plasma sources; Resistors;
