Turbulence spectra in Tore Supra tokamak, from scattering experiment
Anomalous transport is responsible for particle and energy losses which hinder attempts to achieve ignition in a tokamak plasma. This anomalous transport is linked, via the radial particle flux, with the electronic density fluctuations. Density fluctuations with wavelengths in the range 0.2 to 2 cm can be measured on Tore Supra by coherent Thomson scattering, using a CO(2) laser scattering system, ALTAIR. The heterodyne detection system of this diagnostic makes it possible to associate positive or negative frequency shifts with electron or ion diamagnetic drifts. The frequency spectra are presented, and a model developed to fit. The model is based on the existence of a shear layer with an inversion point of the radial electric field, near the plasma edge at r = rho(s). The results of the modelling show good agreement with experiment, with rho(s)/a having a value 0.93 +/- 0.05, where a is the minor radius of the plasma. The behaviour of this shear layer with density and plasma current is detailed.
Bibliographic Reference: Paper presented: Physiques en Herbe 92, Marseille (FR), July 5-10, 1992
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Record Number: 199310105 / Last updated on: 1994-11-29
Original language: en
Available languages: en