The density of He (23S) atoms in a high-pressure pulsed helium-neon laser discharge

Abstract

The absorption of the helium 388.9 nm line by a high-pressure pulsed helium-neon laser discharge has been measured. The density and decay rate of density of He(23.s) metastable atoms in the discharge have been estimated. While the accuracy of the decay rate measurements is of the order of 5%, that of the density measurements is probably not better than 20%, because of the difficulty of determining the shape of the collision-broadened absorption line. The measured decay rates of He(23.s) atoms are given for mixtures with helium and neon pressures in the range 80 to 260 torr and 4 to 30 torr respectively. The decay rate at a fixed neon pressure is shown to be independent of the helium pressure, and to be proportional to the neon pressure at a fixed helium pressure. Agreement with values obtained by extrapolating results from low-pressure measurements of Benton et al, in 1962 is good. Measurements of the peak density of He(23S) as a function of the pulsed excitation voltage of the laser discharge are given and well with calculated values given by Langdon in 1968. The energy conversion efficiency for the production of He(23S) atoms deduced from the foregoing results is between 15 and 30%.