Abstract: An apparatus for preionization of gas in a pulsed gas laser by means of soft X-ray radiation comprises an elongated cathode (26) which is heated by thermal radiation or electron bombardment and which is arranged parallel to a likewise elongated anode (18) in an evacuated housing.

Abstract: An apparatus for preionization of a pulsed gas laser comprises corona preionization electrodes (12, 12') which are each arranged adjacent a respective associated main electrode (10, 10'). To generate an effective preionization with low constructional and circuit expenditure the preionization electrodes (12, 12') are set under voltage with the same high-voltage source (16) which also supplies the main electrodes (10, 10') with voltage. By means of an inductance (30) a time delay is set between the excitation of the preionization electrodes and the triggering of the main discharge between the main electrodes (10, 10').

Abstract: A pulsed gas-discharge laser, in particular an excimer laser, comprises main discharge electrodes (10, 10a) of erosion-resistant metal between which laser gas flows with high velocity to replace the laser gas between the main discharge electrodes from laser pulse to laser pulse. For preionizing the laser gas two X-ray radiation sources (30, 30a) are arranged adjacent one main discharge electrode (10). The flow path (18) of the laser gas is formed partially by flow bodies (16, 16a, 32, 32a) which consist of a material which has a high secondary emissive power with regard to the X-ray radiation. The secondary radiation is so configured that it promotes the preionization.