Radial profiles of excited ions and electron density in the hollow cathode He/Zn laser

Relative efficiencies for the excitation of zinc ion laser levels in a hollow cathode He/Zn laser have been investigated by monitoring their radial profiles of spontaneous emission. Emission profiles of lines from high-lying Zn II levels are consistent with a simple model of excitation involving thermal energy charge transfer reactions. However, lines originating from lower-lying levels exhibit profiles which indicate the presence of an extra source of excitation in addition to the Penning reactions which dominate their excitation under afterglow conditions. Possible sources of this extra excitation are discussed. Radial profiles of absolute electron density are deduced from the excitation profiles with the help of measurements of the absolute intensity of the 6102 and 4912 AA emission lines of Zn II.