Physics of the L to H transition in the DIII-D tokamak

Journal Article · Fri Jun 01 00:00:00 EDT 1990 · Physics of Fluids B; (USA)

DOI:https://doi.org/10.1063/1.859564· OSTI ID:6800167

Burrell, K H; Carlstrom, T N; Doyle, E J; Gohil, P; Groebner, R J; Lehecka, T; Luhmann, Jr, N C; Matsumoto, H; Osborne, T H; Peebles, W A; Philipona, R ^[1]

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1. General Atomics, San Diego, California 92138 (USA)

The L to H transition in the DIII-D tokamak ({ital Plasma} {ital Physics} {ital and} {ital Controlled} {ital Nuclear} {ital Fusion} {ital Research} 1986 (IAEA, Vienna, 1987), Vol. I, p. 159) is associated with a decrease in the edge density and magnetic fluctuations. In addition, in single-null divertor plasmas, a reduction in the heat flux asymmetry between the inner and outer divertor hit spots occurs. These observations indicate that the L to H transition is associated with the reduction in anomalous, fluctuation-connected transport across the outer midplane of the plasma. Magnetic fluctuations are measured with a poloidally distributed set of Mirnov loops while density fluctuations are detected with multiple fixed-frequency microwave reflectometers. Spectroscopic observations of edge poloidal and toroidal rotation have allowed the inference that the radial electric field just inside the separatrix is negative in the L mode and becomes more negative at the L to H transition. These changes in fluctuations and in the edge electric field occur in plasmas where the H mode is created by neutral beam heating, electron cyclotron heating, and even by Ohmic heating alone. Accordingly, these changes are characteristic of the H mode and are not artifacts of the heating method. Several published theories of the L to H transition involve the effects of the electric field and edge plasma rotation. The observations in this paper have been critically compared with these theories.

• DOE Contract Number: AC03-89ER51114
• OSTI ID: 6800167
• Journal Information: Physics of Fluids B; (USA), Vol. 2:6, Issue 6; ISSN 0899-8221
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
TOKAMAK DEVICES
PLASMA CONFINEMENT
ASYMMETRY
CORRELATIONS
END EFFECTS
FLUCTUATIONS
HEAT FLUX
MODIFICATIONS
OSCILLATION MODES
PLASMA DENSITY
THERMONUCLEAR REACTIONS
CLOSED PLASMA DEVICES
CONFINEMENT
NUCLEAR REACTIONS
NUCLEOSYNTHESIS
SYNTHESIS
THERMONUCLEAR DEVICES
VARIATIONS
700101* - Fusion Energy- Plasma Research- Confinement
Heating
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