Spectroscopic study of edge poloidal rotation and radial electric fields in the DIII-D tokamak
Doppler-shift spectroscopy has shown that finite values of poloidal rotation velocity {upsilon}{sub {theta}} and of radial electric field E{sub r} exist at the edge of a tokamak plasma and that dramatic increases occur in these parameters at an L-H transition. E{sub r} is negative in the L-mode and becomes more negative in the H-mode; {upsilon}{sub {theta}} increases in magnitude at the transition. In addition, the radial gradients (shear) of {upsilon}{sub {theta}} and E{sub r} are large and these gradients also increase at the L-H transition. These results are based on measurements of Doppler shifts of light emitted by He II ions, located in a region about 1--3 cm inside the separatrix. These observations have been made with horizontally-viewing and vertically-viewing spectrometer systems on the DIII-D tokamak. The nearly orthogonal views of these systems are used to determine the plasma's flow velocity in terms of the orthogonal sets {upsilon}{sub {theta}} and {upsilon}{sub {phi}} or of {upsilon}{sub {perpendicular}} and {upsilon}{sub {parallel}}. Knowledge of {upsilon}{sub {perpendicular}} is used to calculate E{sub r} from the force balance equation for a single ion species. The existing results impose constraints on theories of the L-H transition. More detailed studies of the spatial profiles and temporal evolution of {upsilon}{sub {theta}} and E{sub r} will be made with upgraded instrumentation, which is now coming on-line. 28 refs.
- Research Organization:
- General Atomics, San Diego, CA (USA)
- Sponsoring Organization:
- DOE/ER
- DOE Contract Number:
- AC03-89ER51114
- OSTI ID:
- 6503693
- Report Number(s):
- GA-A-20100; CONF-900557-28; ON: DE91002706; TRN: 90-035692
- Resource Relation:
- Conference: 8. topical conference on high-temperature plasma diagnostics, Hyannis, MA (USA), 6-10 May 1990
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
DOUBLET REACTORS
PLASMA DIAGNOSTICS
PLASMA SCRAPE-OFF LAYER
EMISSION SPECTROSCOPY
DOPPLER EFFECT
ELECTRIC FIELDS
ELECTRON DENSITY
ELECTRON TEMPERATURE
H-MODE PLASMA CONFINEMENT
MAGNETIC FIELDS
ROTATING PLASMA
BOUNDARY LAYERS
CONFINEMENT
LAYERS
PLASMA
PLASMA CONFINEMENT
SPECTROSCOPY
THERMONUCLEAR REACTORS
TOKAMAK TYPE REACTORS
700102* - Fusion Energy- Plasma Research- Diagnostics