Role of the Edge Electric Field and Microturbulence in the L-H Transition

Conference · Mon Oct 01 04:00:00 EDT 1990

OSTI ID:6038045

Groebner, R. J. ^[1]; Peebles, W. A. ^[2]; Burrell, K. H. ^[1]; Carlstrom, T. N. ^[1]; Gohil, P. ^[1]; Seraydarian, R. P. ^[1]; Doyle, E. J. ^[2]; Philipona, R. ^[2]; Matsumoto, H. ^[3]; Cluggish, B. ^[4]

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1. General Atomics, San Diego, CA (United States)
2. Univ. of California, Los Angeles, CA (United States)
3. Japan Atomic Energy Research Inst. (JAERI), Tokai (Japan)
4. 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 v_θ abruptly increases, implying that the radial electric field E_r becomes more negative, and the level of density fluctuations is abruptly suppressed in a narrow region at the plasma edge. The absolute values of E_r and v_θ have maxima within 1-2 poloidal gyroradii p_iθ of the plasma edge, indicating that large negative and positive gradients of E_r and v_θ exist near the plasma edge in a region called the “shear” layer. Density fluctuations are reduced and the gradients of T_i, T_e, n_e 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 E_r or v_θ cause a suppression of microturbulence, resulting in increases in the T_i 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
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700101* -- Fusion Energy-- Plasma Research-- Confinement
Heating
& Production
CONFINEMENT
DOUBLET REACTORS
ELECTRIC FIELDS
ELECTRON DENSITY
ELECTRON TEMPERATURE
FLUCTUATIONS
H-MODE PLASMA CONFINEMENT
ION TEMPERATURE
PLASMA CONFINEMENT
THERMONUCLEAR REACTORS
TOKAMAK TYPE REACTORS
TURBULENCE
VARIATIONS