Temperature diagnostic for laser-induced plasma by electron collision model

In this paper, using the collisions between ion and free electron, we analyze the conditions of electron collision equilibrium (ECE) for laser-induced plasma (LIP). Considering the collision excitation and de-excitation, we discuss the principle for temperature diagnostic for the three level ions for LIP. Taking the Ne v ion spectral lines in infrared as an example, for the intensity ratio of the (3-2) transition to the (2-1) transition, we compare the temperature in local thermal equilibrium and electron collision equilibrium when the intensity ratio varies from 0 to 1.8, and we obtain some important conclusions. This discussion is useful in the LIP diagnostic under the conditions of electron collision equilibrium.