Gain calculated versus on the mixture of gas pressure in the He-Ne laser

In this paper, we have calculated the gain in terms of gas mixture pressure in helium-neon laser for the red wavelength 633nm all conditions have been assumed such constant discharge power and pipe diameter and pipe length. In solving these equations, it is initially assumed that the transition of 1s5to2p4 and also rate of emission and absorption between the two levels are not important. Then we made the transition into account and it was found that the transition of 1s5to2p4 and the rate of emission and absorption between the two levels 3s2 and 2p4, are important transitions. That they cannot be ignored and it has better compatibility with the experimental results.