Waveguiding in dense relaxing gases and its applications to chemical and gasdynamic lasers

A series of examples is presented which illustrate laser action in gasdynamic flows inside the cavities of continuous-flow lasers; the examples consist of shock waves in a chemically reacting H2-F2 mixture, and an object with a cooled surface immersed in a flow of dissociating diatomic gas. These gaseous dielectric waveguides localize the radiation in narrow regions of inverted population and allow the use of high flow rates in lasers. In the case of waveguiding and amplification in a high-pressure HF laser a gain of 0.01/cm is predicted; it is also noted that the high pressure (much larger than 1 atm) in the wake of the shock makes it unnecessary to discharge waste gases into the atmosphere. Similar gain is predicted for the case of localization and amplification of light in the boundary layer by radiative recombination of atoms; in the case of localization and population inversion in boundary layers of CO2-N2-H2O flows, however, the gain is determined to be 0.3/m.