Progress of Negative Ion Source Improvement in N-NBI for JT-60U

Journal Article · Mon Sep 15 00:00:00 EDT 2003 · Fusion Science and Technology

OSTI ID:20849566

Kawai, M ^[1]; Akino, N ^[1]; Ebisawa, N ^[1]; Grisham, L ^[2]; Hanada, M ^[1]; Honda, A ^[1]; Inoue, T ^[1]; Kazawa, M ^[1]; Kikuchi, K ^[1]; Kuriyama, M ^[3]; Kusanagi, N ^[1]; Mogaki, K ^[1]; Noto, K ^[1]; Ohga, T ^[1]; Ooshima, K ^[1]; Tanai, Y ^[1]; Umeda, N ^[1]; Usui, K ^[1]; Yamamoto, T ^[1]; Yamazaki, H ^[1] ; Watanabe, K ^[1]

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1. Naka Fusion Research Establishment (Japan)
2. Princeton Plasma Physics Laboratory (United States)
3. Japan Atomic Energy Research Institute (Japan)

The negative-ion based neutral beam injection system developed by JAERI for JT-60U has been intended to generate a 500 keV and 10 MW beam for 10 seconds with two ion sources. Technical efforts to decrease heat loads on the accelerator grids, to improve non-uniformity of the source plasma, to increase voltage holding of the accelerator, and to optimize the operational parameters have been conducted intensively. A step-down control of the filament voltage was very effective to keep the acceleration current constant during the pulse duration. To suppress degradation of voltage holding of the accelerator, protection spark gaps of {approx}178 kV for each stage, its gap length is 73 mm, were confirmed to be effective.As results of these improvements, as of June 2002, the maximum injection power has reached 6.2 MW, and a pulse length has attained 10 seconds of the design value with a 2.6 MW beam.

• OSTI ID: 20849566
• Journal Information: Fusion Science and Technology, Journal Name: Fusion Science and Technology Journal Issue: 2 Vol. 44; ISSN 1536-1055
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ACCELERATION
ACCELERATORS
ANIONS
BEAM INJECTION HEATING
DESIGN
ELECTRIC POTENTIAL
HEATING LOAD
ION SOURCES
JT-60U TOKAMAK
KEV RANGE
NEUTRAL ATOM BEAM INJECTION
PLASMA
PULSES
SPARK GAPS