ABSTRACT
The computations relative to a gas-dynamic laser can be very complex if one considers that it is necessary to bring together topics like non-equilibrium gas dynamics, chemical kinetics and the optics of the extraction. In order to give a rapid outline of the main characteristics of a gas-dynamic laser, a very simple model has been developed, in which the geometry of the flow is assumed to be one-dimensional, the gas model is assumed to be a two-level model, and the optics of the extraction is the mopa one, in which the flowing gas medium is used as a power amplifier of a master oscillator, this being a primary laser beam introduced in the gas in which the inversion has been achieved. With reference to figure 1, we assume that the process is characterized by the following parameters:
The ratio B between the input flux F i and the maximum available laser flux F g. (Notice that in order to preserve the one-dimensionality, two symmetric beams have been considered.) https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781003069607/20ec9e44-075a-46be-938f-00ca0d5bf996/content/fig21_1.tif"/>
The angle of inclination θ of the input beam to the axis of the flow.
The ratio G between the characteristic amplification length l 0 (the inverse of the small-signal gain), and the collisional de-excitation length l c of the upper level.
The ratio P between the characteristic amplification length l 0 and the extinction length l p of the beam due to the turbulent fluctuations of the refractive index.
