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Thomson diffusion is a diagnostic technique designed to obtain the temperature and the electron density of the plasma. It works by measuring Doppler enlargement in the spectrum of a laser beam diffused by thermally agitated electrons. In Tore Supra an Nd:YAG laser beam was used to analyse the bulk of the plasma and an ND:glass laser was used for diagnostics in the boundary area. 3-channel spectrometers fitted with interference filters and avalanche photodiodes were pointed towards the beams through a medial porthole. After calibration by integrating spectral response, electron gain and beam/detector coupling, the temperature was obtained by comparing the relationship between signals from two adjacent spectral channels with a function calculated from spectral responses recorded in the laboratory; the density was obtained from the product of the signal of a channel and a function of the temperature. These measurements correlated well with those obtained using other diagnostic techniques.

Additional information

Authors: AGOSTINI E, CEA, Département de Recherches sur la Fusion Contrôlée, Saint-Paul-lez-Durance (FR);CHIES T ET AL., CEA, Département de Recherches sur la Fusion Contrôlée, Saint-Paul-lez-Durance (FR)
Bibliographic Reference: Paper presented: 2ème Congrès de la Division de Plasma, Orsay (FR), Sept. 3-4, 1990
Availability: Text not available
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