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SPRED, Zeff,CER spect. & MSE

315 R-0

CER

The Charge Exchange Recombination (CER) Spectroscopy system is used to measure ion temperature, poloidal and toroidal rotation speed, impurity density. These are determined from the Doppler broadening, Doppler shift, and total intensity of the spectroscopic line. In addition, by using the radial force balance equation, the radial electric field in the plasma can be determined from these other quantities.

The desired signal for the spectroscopic measurement is produced by charge exchange between neutrals in the neutral beams and ions in the plasma. Typically, we use lines radiated by charge exchange with fully stripped ions of low Z impurities (e.g. carbon, boron), since they exist everywhere in the discharge. The measurement is spatially localized at the point where the viewchord crosses the neutral beam. The system can measure spectral lines in the wavelength range from 300 nm to 800 nm; the best sensitivity is in the visible and near IR from 400 to 800 nm.