Sidewall muffler design for pulsed exciplex lasers

Sidewall mufflers are used in pulsed exciplex lasers to rapidly attenuate pressure waves and restore cavity medium homogeneity at successive pulses. The technical basis for designing these is reviewed in the paper with primary focus on the near-cavity region and emphasis on physical understanding. The approach combines rudimentary theory and flow visualization, starting with simplest situation and building toward a more complete picture. Important results are as follows: longitudinal wave attenuation in a finite capacity muffler involves a balance between precursor pulse decay and recompression wave strength which defines an optimum configuration. Acoustic absorber is required in the backing volume, and a basis for choosing its resistivity is indicated. The contribution of a close-in muffler to transverse wave decay within the laser cavity is also characterized. Further, an entropy wave is shown to be generated within a muffler which is confined to the vicinity of the sidewalls. Other entropy sources in a closed loop flow system are noted.