Effects of Flow Velocity on Repetitive Pulsed Discharge Uniformity in ArF Excimer Laser Gas Mixtures

Achieving a uniform high-energy discharge at high repetition rates is a fundamental challenge in the scaling of high-pressure gas lasers. Herein, we demonstrate the effect of gas flow velocity on the discharge mode transition and uniformity improvement in repetitively pulsed discharges in a 2 atm ArF excimer laser mixture using 500-ps time-resolved imaging and optical emission spectroscopy. We found that gas flow suppresses filamentation primarily by enhancing gas-density recovery under the present experimental conditions. In contrast, neutral species recovery likely plays a coupled, secondary role, thereby reducing local overheating and distortion of the reduced electric field in the filament channels. The critical flow velocity for quasi-uniform discharge follows a linear scaling with the repetition frequency, which provides a practical design criterion for the stable operation of high-repetition-rate ArF excimer lasers.