Abstract: An excimer laser includes a laser housing containing a lasing-gas mixture including a halogen. Contaminants including particulate matter and a metal halide vapor are generated in the lasing-gas mixture during operation of the laser. A gas-cleaning arrangement extracts lasing-gas mixture from the housing and passes the lasing-gas mixture through an electrode assembly. A repeatedly pulsed gas discharge is created in the electrode assembly by driving the electrode assembly with repeated high-power short-duration pulses. The pulsed discharge causes disintegration of the metal halide vapor and electrostatic trapping in the electrode assembly of the particulate matter and products of the metal halide disintegration.