Laser action in ionized selenium

A study was made of the laser action due to transitions in selenium ions. Pulsed and continuous operation were studied. It was found that under pulse-discharge conditions the upper energy levels could be populated by election excitation from the ground state of the atom and by charge exchange between helium ions and neutral selenium atoms. The dependence of the output power on the discharge conditions was determined in the continuous operation case. The plasma parameters were measured and the rate of pumping of the upper laser levels was determined for the charge-exchange and electron-excitation processes. A comparison of the calculated and measured pumping rates indicated that the main contribution to the population inversion in the continuous case was made by the charge-exchange mechanism.