Effect of stimulation emission on hydrogen RRLs. The frequency-integrated intensities of the Hnα line calculated under LTE assumption (solid line) and using non-LTE method without and with the effect of radiation field on departure coefficients (dashed and dash-dotted line) vs. principal quantum number n are plotted in the top panel. The total optical depths at the frequencies of the Hnα lines are presented in the bottom panel. The red vertical lines indicate the positions of the continuum optical depth τ_vC = 1 and 5.