Transverse acoustic waves in pulsed lasers

Acoustic waves arise in pulsed lasers because waste heat is added rapidly in the cavity as a result of the laser pumping process. Transverse waves are the result of nonuniform pumping transverse to the flow direction. This paper will be based on linear acoustics and has the objective of understanding certain processes that are relevant to attenuation of transverse waves during the intra-pulse time. Topics include (1) waves in an infinite parallel hard-walled duct with baseline flow; (2) purely transverse waves between parallel walls with an absorber on one wall; and (3) the effect of tilted walls in an idealized configuration. Examples are chosen to apply to electric discharge and chemical lasers (uniform deposition not extending to walls) as well as excimer lasers pumped by opposed e-beams (distributed deposition extending to walls).