Solar plasma diagnostic for O III spectral lines by using the collision excitation model

Abstract

In this paper, using the collisions between ions and free electrons, we discuss the conditions for electron collision equilibrium. Using collision excitation and de-excitation, we discuss a method for a solar temperature diagnostic for three-level ions. Taking the O III ion as an example, for the intensity ratio of the (2-1) transition to the (3-2) transition, we calculate the temperature when the intensity ratio varies from 10 to 200, and we obtain some useful conclusions. This discussion is important for solar plasma diagnostic under the conditions of electron collision equilibrium.