A laser-based technique for the direct testing of rate constants used in the collisional–radiative model, for application in the analysis of the supersonic He beam diagnostic, is presented. The time evolution of populations of some relevant excited levels upon the laser pumping of one of them is simulated by solving the corresponding system of coupled differential equations. Transitions have been identified which show good sensitivity in the changes induced by the laser interaction to the particular values of the relevant collisional rate constants for both the singlet and triplet systems of the He atom. The available experimental set-up and some previous results on the implementation of the technique in TJ-II are also shown.