Behaviors of excitation discharge on excimer laser in nonuniform gas density distribution

In excimer lasers, the excitation discharge causes various instabilities in subsequent discharges which collapse the highly-repetitive operation. The paper inquires into the effects of the gas density depletion on the excitation discharge instability eliminating the influences of the shock waves, the residual ions and the discharge products. We have found that the big density nonuniformity tends to induce the arc without the shocks, ions and products. The transition from glow to arc with respect to the nonuniformity occurs almost discontinuously. On the other hand, the second discharge on the double-pulse discharge in stable gas becomes an arc in much smaller nonuniformity, where the transition occurs very slowly. Therefore, it can be suggested that the discharge instability is also caused by some factors other than gas density depletion.