Estimated lifetime of an He-Ne microwave-pumped laser using a spectroscopic method

The lifetime of a microwave-pumped He-Ne laser was estimated by monitoring the pressure and composition of the gas mixture in a sealed capillary with a working volume of 0.8 cm. The lifetime of the laser was shown to be determined by helium leakage from the working volume. It is suggested that another mechanism for gas leakage in addition to helium diffusion may be involved: namely vaporization of the glass wall, observed in lasers pumped at 27 MHz. The importance of stationary fields for the case of a microwave (1000 MHz) discharge is assessed, and a low vaporization efficiency is found which may account for the longer lifetimes of microwave-pumped lasers as compared with RF (27 MHz) pumped lasers.