Improvement of voltage holding capability in the 500 keV negative ion source for JT-60SA.
Voltage holding capability of JT-60 negative ion source that has a large electrostatic negative ion accelerator with 45 cm x 1.1 m acceleration grids was experimentally examined and improved to realize 500 keV, 22 A, and 100 s D- ion beams for JT-60 Super Advanced. The gap lengths in the acceleration stages were extended to reduce electric fields in a gap between the large grids and at the corner of the support flanges from the original 4-5 to 3-4 kV/mm. As a result, the voltage holding capability without beam acceleration has been successfully improved from 400 to 500 kV. The pulse duration to hold 500 kV reached 40 s of the power supply limitation.
Tanaka
Y
Y
Japan Atomic Energy Agency, Naka, Ibaraki 311-0193, Japan. tanaka.yutaka@jaea.go.jp
Hanada
M
M
Kojima
A
A
Akino
N
N
Shimizu
T
T
Ohshima
K
K
Inoue
T
T
Watanabe
K
K
Taniguchi
M
M
Kashiwagi
M
M
Umeda
N
N
Tobari
H
H
Grisham
L R
LR