Interferometric investigation of the plasma in a three-electrode XeCl laser

An experimental investigation was made of optical inhomogeneities in the active medium of a three-electrode XeCl laser with a double discharge. A current prepulse, which appeared during the discharge-formation stage, influenced the profile of the electron density distribution in the plasma. A study was made of the kinetics of changes in the electron density distribution during pumping. Small-scale optical inhomogeneities were detected and they appeared because of growth of discharge microinstabilities. The current density and the duration of the pump pulses needed to ensure a stable discharge were determined.