Dimensionless scaling of the critical beta for onset of a neoclassical tearing mode

Journal Article · Tue Aug 01 04:00:00 EDT 2000 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.874199· OSTI ID:20217084

La Haye, R J ^[1]; Buttery, R J ^[2]; Guenter, S ^[3]; Huysmans, G T. A. ^[4]; Maraschek, M ^[3]; Wilson, H R ^[2]

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1. General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States)
2. Euratom/UKAEA Fusion Association, Culham Science Centre, Abingdon, OX14 3DB, (United Kingdom)
3. Max-Planck Institut fuer Plasmaphysik, Garching, (Germany)
4. JET Joint Undertaking, Abingdon, (United Kingdom)

The islands from tearing modes driven unstable and sustained by the helically perturbed neoclassical bootstrap current often provide the practical limit to long-pulse, high confinement tokamak operation. The destabilization of such ''metastable'' plasmas depends on a ''seed'' island exceeding a threshold. A database from similar regimes [high confinement H-mode with periodic edge localized modes (ELMs) and periodic central sawteeth] was compiled from the tokamaks ASDEX Upgrade (AUG) [Plasma Phys. Controlled Fusion 41, 767 (1999)], DIII-D [Nucl. Fusion 38, 987 (1998)], and JET (Joint European Torus) [Plasma Phys. Controlled Fusion 41, B1 (1999)]. A comparison is made of the measured critical beta for onset of the m/n=3/2 mode (m and n being the poloidal and toroidal Fourier harmonics, respectively) to a model in terms of dimensionless parameters for the seed and threshold islands. This modeling is then used for extrapolation to a reactor-grade tokamak design such as ITER/FDR (International Thermonuclear Experimental Reactor/Final Design Report) [Nucl. Fusion 39, 2137 (1999)]; this indicates that the seed island from sawteeth could be too small to sufficiently disturb the metastable plasma and excite the m/n=3/2 neoclassical tearing mode. (c) 2000 American Institute of Physics.

• OSTI ID: 20217084
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 8 Vol. 7; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
HIGH-BETA PLASMA
ITER TOKAMAK
PLASMA CONFINEMENT
SAWTOOTH OSCILLATIONS
TEARING INSTABILITY
THEORETICAL DATA
TOKAMAK DEVICES