Scheme for evaluating T/sub e//T/sub i/ and Z-bar by light scattering

When highly ionized impurities are present in a plasma, the scattered spectrum of the major ion species can be distorted in a complicated way. A method is given by which T/sub e//T/sub i/ and Z-bar (equivalentsummationn/sub j/z/sub j/2/n/sub e/) can be measured which does not require any knowledge of the mass, charge state, or concentration of the impurity species. A generalization of the Salpeter approximation for the integrated cross section is proven. The result is that the total cross section is a function of α (equivalent 1/Klambda/sub D/), T/sub e//T/sub i/, and Z-bar as long as the temperature of all ion species is the same and T/sub e//T/sub i/ is not too large. Thus a measurement of the integrated ion cross section at two different scattering angles can yield T/sub e//T/sub i/ and Z-bar. This method is insensitive to magnetic fields and to moderate electron drifts. For 1approximately-less-thanT/sub e//T/sub i/, Z-barapproximately-less-than3 the cross section must be measured to an accuracy of about 3% to give T/sub e//T/sub i/ to within 10% and Z-bar within 20%