Sawtooth oscillations in shaped plasmas

Journal Article · Tue May 15 00:00:00 EDT 2007 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.2436849· OSTI ID:20975024

Lazarus, E A ^[1]; Luce, T C; Burrell, K H; Chu, M S; Ferron, J R; Hyatt, A W; Lao, L L; Lohr, J; Osborne, T H; Petty, C C; Politzer, P A; Prater, R; Scoville, J T; Strait, E J; Turnbull, A D ^[2]; Austin, M E; Waelbroeck, F L ^[3]; Brennan, D P ^[4]; Jayakumar, R J; Makowski, M A ^[5]

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1. Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)
2. General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States)
3. University of Texas, Austin, Texas 78712 (United States)
4. University of Tulsa, Tulsa, Oklahoma 74104 (United States)
5. Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

The role of interchange and internal kink modes in the sawtooth oscillations is explored by comparing bean- and oval-shaped plasmas. The n=1 instability that results in the collapse of the sawtooth has been identified as a quasi-interchange in the oval cases and the internal kink in the bean shape. The ion and electron temperature profiles are followed in detail through the sawtooth ramp. It is found that electron energy transport rates are very high in the oval and quite low in the bean shape. Ion energy confinement in the oval is excellent and the sawtooth amplitude ({delta}T/T) in the ion temperature is much larger than that of the electrons. The sawtooth amplitudes for ions and electrons are comparable in the bean shape. The measured q profiles in the bean and oval shapes are found to be consistent with neoclassical current diffusion of the toroidal current, and the observed differences in q largely result from the severe differences in electron energy transport. For both shapes the collapse flattens the q profile and after the collapse return to q{sub 0} > or approx. 1. Recent results on intermediate shapes are reported. These shapes show that the electron energy transport improves gradually as the plasma triangularity is increased.

• OSTI ID: 20975024
• Journal Information: Physics of Plasmas, Vol. 14, Issue 5; Other Information: DOI: 10.1063/1.2436849; (c) 2007 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
AMPLITUDES
CURRENTS
DIFFUSION
ELECTRON TEMPERATURE
ELECTRONS
ION TEMPERATURE
IONS
KINK INSTABILITY
NEOCLASSICAL TRANSPORT THEORY
PLASMA
PLASMA CONFINEMENT
PLASMA WAVES
SAWTOOTH OSCILLATIONS
SHAPE