Long pulse high performance plasma scenario development for the National Spherical Torus Experiment

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

DOI:https://doi.org/10.1063/1.2177645· OSTI ID:20783133

Kessel, C E; Bell, R E; Bell, M G; Gates, D A; Kaye, S M; LeBlanc, B P; Menard, J E; Phillips, C K; Synakowski, E J; Taylor, G; Wilson, R; Harvey, R W; Mau, T K; Ryan, P M; Sabbagh, S A ^[1]

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1. Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

The National Spherical Torus Experiment [Ono et al., Nucl. Fusion, 44, 452 (2004)] is targeting long pulse high performance, noninductive sustained operations at low aspect ratio, and the demonstration of nonsolenoidal startup and current rampup. The modeling of these plasmas provides a framework for experimental planning and identifies the tools to access these regimes. Simulations based on neutral beam injection (NBI)-heated plasmas are made to understand the impact of various modifications and identify the requirements for (1) high elongation and triangularity (2) density control to optimize the current drive (3) plasma rotation and/or feedback stabilization to operate above the no-wall {beta} limit, and (4) electron Bernstein waves (EBW) for off-axis heating/current drive (H/CD). Integrated scenarios are constructed to provide the transport evolution and H/CD source modeling, supported by rf and stability analyses. Important factors include the energy confinement, Z{sub eff}, early heating/H mode, broadening of the NBI-driven current profile, and maintaining q(0) and q{sub min}>1.0. Simulations show that noninductive sustained plasmas can be reached at I{sub P}=800 kA, B{sub T}=0.5 T, {kappa}{approx_equal}2.5, {beta}{sub N}{<=}5, {beta}{<=}15%, f{sub NI}=92%, and q(0)>1.0 with NBI H/CD, density control, and similar global energy confinement to experiments. The noninductive sustained high {beta} plasmas can be reached at I{sub P}=1.0 MA, B{sub T}=0.35 T, {kappa}{approx_equal}2.5, {beta}{sub N}{<=}9, {beta}{<=}43%, f{sub NI}=100%, and q(0)>1.5 with NBI H/CD and 3.0 MW of EBW H/CD, density control, and 25% higher global energy confinement than experiments. A scenario for nonsolenoidal plasma current rampup is developed using high harmonic fast wave H/CD in the early low I{sub P} and low T{sub e} phase, followed by NBI H/CD to continue the current ramp, reaching a maximum of 480 kA after 3.4 s.

• OSTI ID: 20783133
• Journal Information: Physics of Plasmas, Vol. 13, Issue 5; Other Information: DOI: 10.1063/1.2177645; (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
ASPECT RATIO
BEAM INJECTION HEATING
BERNSTEIN MODE
ELECTRIC CURRENTS
ELECTRONS
H-MODE PLASMA CONFINEMENT
NEUTRAL ATOM BEAM INJECTION
NSTX DEVICE
PERFORMANCE
PLASMA
PLASMA BEAM INJECTION
PLASMA DENSITY
PLASMA INSTABILITY
PLASMA SIMULATION
PLASMA WAVES
PULSES
ROTATION
SPHERICAL CONFIGURATION