Diagnostics of hot plasma by spectra of He-like ions

Abstract

Collisional-radiative models of He-like ions C V, Mg XI, Si XIII, and Fe XXV (n = 1, 2, 3) are constructed for the case of ionizing plasma. The line intensity ratios which are of interest from the viewpoint of plasma diagnostics are calculated. The dependence of widely used ratios R and G on the number of considered levels is studied. Approximation formulas are proposed for R and G. It is shown that the consideration of collisions with protons is inessential in most cases. New lines for diagnostics are proposed. For the considered intensity ratios, regions of sensitivity to the plasma density and temperature are determined.