Long Pulse Operation on NBI Systems for JT-60U

Journal Article · Fri Apr 15 04:00:00 EDT 2005 · Fusion Science and Technology

OSTI ID:20849956

Akino, N; Ebisawa, N ^[1]; Honda, A ^[1]; Ikeda, Y ^[1]; Kawai, M ^[1]; Kazawa, M ^[1]; Mogaki, K ^[1]; Ohga, T ^[1]; Umeda, N ^[1]; Usui, K ^[1]; Yamamoto, T ^[1]; Grisham, L ^[2]

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1. Japan Atomic Energy Resaerch Institute (Japan)
2. Princeton Plasma Physics Laboratory (United States)

In the neutral beam injection (NBI) system, an extension of the pulse duration up to 30 sec has been intended to study quasi-steady state plasma on JT-60U. The four positive-ion based (P-NBI) units, which tangentially inject neutral beam to plasma, were mainly modified on the electric power supplies and the beam limiters to extend the pulse duration up to 30 sec with 2 MW at 80 keV per each. The seven P-NBI units, each of which perpendicularly injects for 10 sec, were conducted to operate in series for the total pulse duration of 30 sec. The ion source of the negative-ion based (N-NBI) unit, whose target beam energy is 500 keV for 10 sec, was also modified to reduce the heat load of the grid for long pulse operation. The reduction of the re-ionization of the neutral beam in the beam drift duct was a key to achieve a long pulse injection. It was found that the pressure rise in the beam drift duct, which gives the re-ionization rate, depended on the temperature of the re-ionization plates during NBI injection. Up to now, it was attained successfully that the pulse duration of the tangential P-NBI unit was extended up to 30 sec. 310 MJ of the total integrated injection energy into JT-60U plasma was achieved, including the negative-ion based NBI operation for 17 sec at 366 keV.

• OSTI ID: 20849956
• Journal Information: Fusion Science and Technology, Journal Name: Fusion Science and Technology Journal Issue: 3 Vol. 47; ISSN 1536-1055
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ANIONS
HEATING LOAD
ION SOURCES
IONIZATION
JT-60U TOKAMAK
KEV RANGE
LIMITERS
NEUTRAL ATOM BEAM INJECTION
OPERATION
PLASMA
PULSES
STEADY-STATE CONDITIONS