Multichannel Thomson scattering system for the tokamak TFR based on two-detector spectrum analyzers

In actual and future large tokamaks, the electron temperature T(e) and density n(e) profiles must be measured with a single discharge and laser shot. We have reached this objective in a rather simple way: T(e) is deduced from the ratio of powers scattered into two large spectral intervals, while n(e) is deduced from the absolute power detected in one of the intervals and from the knowledge of T(e). We discuss this method and describe the spectrometers designed for this purpose and their calibration. T(e), n(e) profiles are obtained in a single shot on TFR with a nine-channel scattering system based on these two-detector spectrometers.