Laser-induced fluorescence characterization of ions emitted from hollow cathodes

Laser-induced fluorescence (LIF) was used to measure the mean and variance of the velocity distribution of xenon ions emitted from two hollow cathode assemblies operating at low power. High-energy ions detected in plume-mode and spot-mode operation are consistent with the potential-hill model of hig h-energy ion production. The distributions of velocities were modeled, yiel ding temperatures on the order of a few electronvolts in plume mode and 1 e V in spot mode. The LIF of neutral xenon atoms in the plumes indicated ther mal temperatures significantly less than the temperatures associated with t he ion velocity distributions.