Role of the Edge Electric Field and Microturbulence in the L-H Transition
- General Atomics, San Diego, CA (United States)
- Univ. of California, Los Angeles, CA (United States)
- Japan Atomic Energy Research Inst. (JAERI), Tokai (Japan)
- Univ. of California, San Diego, CA (United States)
Two clear signatures of the L-H transition in the DIII-D tokamak are that the edge poloidal rotation velocity vθ abruptly increases, implying that the radial electric field Er becomes more negative, and the level of density fluctuations is abruptly suppressed in a narrow region at the plasma edge. The absolute values of Er and vθ have maxima within 1-2 poloidal gyroradii piθ of the plasma edge, indicating that large negative and positive gradients of Er and vθ exist near the plasma edge in a region called the “shear” layer. Density fluctuations are reduced and the gradients of Ti, Te, ne and the carbon density increase in the shear layer at the time of transition. These data qualitatively support theoretical scenarios in which changes in Er or of the gradients of Er or vθ cause a suppression of microturbulence, resulting in increases in the Ti and density gradients.
- Research Organization:
- General Atomics, San Diego, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- AC03-89ER51114
- OSTI ID:
- 6038045
- Report Number(s):
- GA-A-20272; CONF-901025-41; ON: DE91008925; TRN: 91-006744
- Resource Relation:
- Conference: 13. International Conference on Plasma Physics and Controlled Nuclear Fusion Research, Washington, DC (United States), 1-6 Oct 1990
- Country of Publication:
- United States
- Language:
- English
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