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Abstract

Collective Thomson scattering in the far infrared is capable of measuring ion temperatures in tokamak plasmas with good spatial and temporal resolution. The system used at TCA consists of a high power pulsed D(2)O laser and a heterodyne receiver system based on a Schottky barrier diode mixer and a CD(3)Cl laser as local oscillator. A variance of about 12% in the T(i) measurement has been achieved in tokamak plasmas with densities above 1.0 E20/m3. The detection optics have been modified to measure spatial profiles of the ion temperature across the minor plasma radius. Using a single shot laser, the profiles had to be built up from a series of reproducible tokamak discharges. The measurements were performed in high density deuterium plasmas. The T(i) profile was found to be flat in the observed region, from the plasma centre out to 2/3 of the minor radius. In comparison, the T(e) profile was peaked. This was in agreement with the T(i) profile measured by neutral particle analysis, which also showed a large flat central region. While the Thomson scattering yields local values of the ion temperature, the neutral particle analysis provides temperatures which are a weighted average over the line of sight.

Additional information

Authors: NIESWAND C, Centre de Recherches en Physique des Plasmas, Ecole Polytechnique Fédérale de Lausanne, Lausanne (CH);BEHN R, Centre de Recherches en Physique des Plasmas, Ecole Polytechnique Fédérale de Lausanne, Lausanne (CH);SIEGRIST M R ET AL., Centre de Recherches en Physique des Plasmas, Ecole Polytechnique Fédérale de Lausanne, Lausanne (CH)
Bibliographic Reference: Paper presented: 18th European Conference on Controlled Fusion and Plasma Physics, Berlin (DE), June 3-7, 1991
Availability: Text not available
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