Excimer lasers with capacitively excited tubular discharges

The excitation of excimer lasers in tubular discharges results in simple and compact devices needing no preionization. Optical output energies are in the millijoule range. The authors investigated XeF, KrF and ArF lasers for various operating conditions. The lasers consist of capillary glass tubes with two internal electrodes at the ends and an aluminum-foil wrapped around the tube as capacitive electrode. A maximum output energy of 0.3 mJ has been achieved for the XeF laser. The good quality of the discharge is indicated by the observation of spontaneous mode locking. The detailed study of the discharge for different polarities of the electrodes shows that efficient operation with a high gas lifetime can be obtained by a purely capacitively excited discharge. A gas lifetime of about 10,000 pulses for 3 liters gas mixture has been observed. Using a two stage Marx generator to generate 100 kV excitation voltage a maximum output energy of 0.7 mJ was obtained for a gas mixture of Kr, F2 and He with an efficiency of 0.17%. The KrF laser operates also without the buffer gas. Laser action in ArF has been achieved with 15 mJ pulse energy and 10 ns duration