Recent Technological Progress for Advanced Tokamak Research in JT-60U and JFT-2M

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

OSTI ID:20849896

Hosogane, N ^[1]

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1. Japan Atomic Energy Research Institute (Japan)

For steady state advanced tokamak research with long pulse operations, JT-60U tokamak discharge, NBI and RF heating injection durations have been extended from 15 s to 65 s and from 10 s to 30 s respectively mainly by means of modifying their control systems and using derated power levels. In addition, technological issues for their long pulse injections with the heating systems have been solved as follows. The ion source of the negative ion NBI system was modified to increase gas conductance in the accelerator, which reduced the heat load to the grounded grid due to stripping loss to a level that enables operations of 2 MW for 30 s. A new method of controlling the anode voltage has been developed for sustaining the oscillation condition of a gyrotron in the electron cyclotron (EC) system. With this method, the EC injection duration has reached 16 s at 0.4 MW. To avoid serious damage of the LH launcher, a heat-resistant carbon grill LH antenna was implemented on the original stainless steel grill. To date, the advanced tokamak operations have been extended to {beta}{sub N} = 2.1 for 20 s. In JFT-2M, high {beta}{sub N} plasmas had been investigated with the vacuum vessel covered with ferritic steels. {beta}{sub N} of {approx}3.5 was obtained with r{sub wall}/a{approx}1.3-1.6 without serious influence of ferromagnetic walls (r{sub wall} is distance of the wall from a plasma center and a is minor radius of a plasma). This encourages the utilization of ferric steel as a structural material for future reactors.

• OSTI ID: 20849896
• 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
ANODES
ANTENNAS
BEAM INJECTION HEATING
CARBON
CONTROL SYSTEMS
ELECTRIC POTENTIAL
ELECTRONS
FERRITIC STEELS
HEATING LOAD
HEATING SYSTEMS
HIGH-FREQUENCY HEATING
ION SOURCES
JFT-2M TOKAMAK
JT-60U TOKAMAK
NEUTRAL ATOM BEAM INJECTION
PLASMA
PULSES
STAINLESS STEELS
STEADY-STATE CONDITIONS
STRIPPING