Abstract: The gas enclosure of this laser includes a reservoir but no gas exhaust port--or valve leading to such a port or to ambient. Preferably the enclosure is sealed by an essentially permanent-type seal such as a glassblown seal, and connects with no pump, or valve leading to a pump. System life, in intermittent use or low-repetition-rate continuous use, is over a year without gas replenishment. Opposed metal coatings on the exterior of a discharge capillary tube form preionization electrodes, each extending nearly the entire capillary-tube length. These electrodes are energized to establish a transverse discharge inside the capillary tube, with good uniformity of initial ion density along the capillary tube. The electrodes couple to this discharge capacitively, through the capillary-tube wall, thereby isolating electrode materials against chemical reaction with corrosive gases in the system.