• Medientyp: E-Artikel
  • Titel: Exploring a small sawtooth regime in Joint European Torus plasmas with counterinjected neutral beams
  • Beteiligte: Nave, M. F. F. [VerfasserIn]; Koslowski, H. R. [VerfasserIn]; Coda, J. W. [VerfasserIn]; Graves, J. [VerfasserIn]; Buttery, R. [VerfasserIn]; Challis, C. [VerfasserIn]; Giroud, C. [VerfasserIn]; Stamp, M. [VerfasserIn]; de Vries, P. [VerfasserIn]
  • Erschienen: American Institute of Physics, 2006
  • Erschienen in: Physics of plasmas 13, 014503 (2006). doi:10.1063/1.2162528
  • Sprache: Englisch
  • DOI: https://doi.org/10.1063/1.2162528
  • ISSN: 1070-664X
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  • Beschreibung: During a recent reversed toroidal field (B-T) campaign at the Joint European Torus (JET), experiments were performed to investigate the effect on sawteeth of neutral beam injection (NBI)-driven toroidal plasma rotation counter to the direction of the toroidal plasma current and B-T. A power scan at constant density has permitted analytical continuation, into the reversed B-T domain, of previous experiments with forward field and hence corotation. Earlier JET results were confirmed, indicating that counter-NBI results in sawtooth periods shorter than in the Ohmic regime. This study has demonstrated that, whereas with co-NBI the sawtooth period increases with power, with counter-NBI the sawtooth period initially decreases with power passing through a minimum at 4 MW. Clearly this trend also manifests itself in terms of the toroidal plasma rotation, for which a minimum is observed for counter-rotation frequency similar to 3 kHz. Sawteeth smaller than Ohmic sawteeth are found to be easier to obtain with perpendicular counter-NBI, for which heating penetrates deeper into the core. The sign and magnitude of the toroidal rotation, the penetration of heating to the electrons, and the peaking of the fast-ion pressure profile in the core may all play an important role in modifying the sawtooh period. (c) 2006 American Institute of Physics.
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