The spatial distribution of small signal gain in a segmented hollow cathode discharge laser

Abstract

We present measurements of the spatial distribu- tion of the small signal gain in the cross section of a lon- gitudinally segmented hollow cathode discharge. This con- figuration proved to be the most efficient for pumping dif- ferent cathode sputtered metal ion laser transitions excited by thermal energy charge transfer reactions. We performed the measurements for the Cu-II 780: 8n mtransition for dif- ferent currents and buffer gas pressures. At higher pressures there are two peaks in the gain distribution nearer to the cath- ode surface. With increasing current the gain increases faster in the center of the discharge and the gap between the two separate peaks tends to disappear. At the optimum pressure (where the gain is the highest), the gain has a maximum in the center of the discharge. Our results are generally valid for the charge transfer excited cathode sputtered UV metal ion lasers as well. The measured gain values are proportional to the gain of possible continuous VUV laser transitions around 150- 160 nm, where the upper level is common with the upper level of the 780: 8n mtransition.