CALCULATED AR-XVII LINE-INTENSITIES AND COMPARISON WITH SPECTRA FROM THE ALCATOR-C TOKAMAK

Using calculations of collisional excitation rates in He-like argon (A r XVII) and intensity factors and other data for nearby dielectronic s atellites, x-ray line spectra have been synthesized as a function of e lectron temperature and density. The Ar XVII excitation rates were obt ained from interpolations of R-matrix calculations, and are likely to be the best available at present. The resulting spectra are compared w ith spectra observed from high-temperature plasmas in the Alcator C to kamak. The agreement between observed spectra and those calculated usi ng measured values of temperature and density illustrates the accuracy of the calculations, though there are small discrepancies which are l ikely to be connected with wavelengths or intensity factors for the Ar XVI satellites. Thus, argon x-ray line spectra can serve as a means o f diagnosing low-density, astrophysical (in particular solar-flare) pl asmas for which them is no independent means of measuring temperatures .