Progress toward fully noninductive, high beta conditions in DIII-D

Journal Article · Mon May 15 00:00:00 EDT 2006 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.2173627· OSTI ID:20783131

Murakami, M ^[1]; Wade, M R; Greenfield, C M; Luce, T C; Ferron, J R; St John, H E; DeBoo, J C; Osborne, T H; Petty, C C; Politzer, P A; Burrell, K H; Gohil, P; Gorelov, I A; Groebner, R J; Hyatt, A W; Kajiwara, K; La Haye, R J; Lao, L L; Leonard, A W; Lohr, J ^[2]

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1. Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6969 (United States)
2. General Atomics, P. O. Box 85608, San Diego, California 92186-5608 (United States)

The DIII-D Advanced Tokamak (AT) program in the DIII-D tokamak [J. L. Luxon, Plasma Physics and Controlled Fusion Research, 1986, Vol. I (International Atomic Energy Agency, Vienna, 1987), p. 159] is aimed at developing a scientific basis for steady-state, high-performance operation in future devices. This requires simultaneously achieving 100% noninductive operation with high self-driven bootstrap current fraction and toroidal beta. Recent progress in this area includes demonstration of 100% noninductive conditions with toroidal beta, {beta}{sub T}=3.6%, normalized beta, {beta}{sub N}=3.5, and confinement factor, H{sub 89}=2.4 with the plasma current driven completely by bootstrap, neutral beam current drive, and electron cyclotron current drive (ECCD). The equilibrium reconstructions indicate that the noninductive current profile is well aligned, with little inductively driven current remaining anywhere in the plasma. The current balance calculation improved with beam ion redistribution that was supported by recent fast ion diagnostic measurements. The duration of this state is limited by pressure profile evolution, leading to magnetohydrodynamic (MHD) instabilities after about 1 s or half of a current relaxation time ({tau}{sub CR}). Stationary conditions are maintained in similar discharges ({approx}90% noninductive), limited only by the 2 s duration (1{tau}{sub CR}) of the present ECCD systems. By discussing parametric scans in a global parameter and profile databases, the need for low density and high beta are identified to achieve full noninductive operation and good current drive alignment. These experiments achieve the necessary fusion performance and bootstrap fraction to extrapolate to the fusion gain, Q=5 steady-state scenario in the International Thermonuclear Experimental Reactor (ITER) [R. Aymar et al., Fusion Energy Conference on Controlled Fusion and Plasma Physics, Sorrento, Italy (International Atomic Energy Agency, Vienna, 1987), paper IAEA-CN-77/OV-1]. The modeling tools that have been successfully employed to both plan and interpret the experiment are used to plan future DIII-D experiments with higher power and longer pulse ECCD and fast wave and co- and counterneutral beam injection in a pumped double-null configuration. The models predict our ability to control the current and pressure profiles to reach full noninductivity with increased beta, bootstrap fraction, and duration. The same modeling tools are applied to ITER, predicting favorable prospects for the success of the ITER steady-state scenario.

• OSTI ID: 20783131
• Journal Information: Physics of Plasmas, Vol. 13, Issue 5; Other Information: DOI: 10.1063/1.2173627; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
BEAM CURRENTS
BEAM INJECTION HEATING
BOOTSTRAP CURRENT
COMPUTERIZED SIMULATION
DOUBLET-3 DEVICE
ECR CURRENT DRIVE
HIGH-BETA PLASMA
IONS
ITER TOKAMAK
MAGNETOHYDRODYNAMICS
PERFORMANCE
PLASMA BEAM INJECTION
PLASMA CONFINEMENT
PLASMA DIAGNOSTICS
PLASMA INSTABILITY
PLASMA PRESSURE
PLASMA SIMULATION
PULSES
STEADY-STATE CONDITIONS