A preionization device for a gas laser includes an internal preionization electrode having a dielectric housing around it such that the preionization device is of corona type. The internal electrode connects to advantageous electrical circuitry, preferably external to the discharge chamber via a conductive feedthrough. The circuitry reduces the voltage across the dielectric tube of the preionization unit to reduce over-flashing at tube ends and oscillations due to residual energies stored in the dielectric. A semi-transparent mesh electrode between the preionization unit and the discharge area prevents field distortions and discharge instabilities.