Deduction of central plasma parameters from line‐of‐sight averaged spectroscopic observations

• A method is presented to deduce central ion temperature and toroidal rotation velocity fromline-of-sight averaged x-ray spectra from hot plasmas. The analysis is based on atomicdata for the processes that give rise to x-ray spectral lines. Combined with measured electrontemperature and density profiles a synthetic spectrum is calculated. The fit of thissynthetic spectrum to the observed one gives a new level of accuracy to line-of-sight integratedobservations in a considerably extended range of ion temperatures and toroidal rotationvelocities. The choice of model for radial profiles for ion temperature and toroidal rotationvelocity is shown not to be critical. The concentration of the emitting impurity isdeduced from the total line intensity, making use of the absolute calibration of the detectorsensitivity. The effective plasma charge ZeE is derived from the absolute level of thecontinuum radiation. These measurements are based on atomic data for x-ray line andcontinuum radiation and measured electron temperature and density profiles. The results forion temperature and toroidal rotation velocity obtained by this analysis are comparedwith those from visible charge exchange spectroscopy. The observed visible lines are shiftedin wavelength, and their width is reduced, due to the velocity dependence of the crosssection for the charge transfer from the neutral beam particles to the observed impurities. Thetheoretically predicted magnitude of these effects is verified. When the results fromvisible charge exchange spectroscopy are corrected for the cross-section effects, excellentagreement of central ion temperature and rotation velocity with the results of this new analysis is obtained

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