# Review of theoretical gain-optimization studies in $10.6 \mu m$ $CO_2-N_2$ gasdynamic lasers

Reddy, KPJ and Reddy, NM (1985) Review of theoretical gain-optimization studies in $10.6 \mu m$ $CO_2-N_2$ gasdynamic lasers. In: Pramana: Journal of Physics, 25 (1). pp. 101-117.

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A review with 18 refs. A comprehensive theoretical analysis of optimization of gain in $CO_2-N_2$ gasdynamic laser employing wedge or conical or hyperbolic nozzles with either $H_2O$ or He as the catalyst is presented. After a review of previous woprk, the usual governing equations for the steady inviscid quasi-1-dimensional flow in a supersonic nozzle of a gasdynamic laser are used to obtain similar solutions for the various flow quantities, which variables are subsequently used to optimize the small-signal gain on the P(20) line of the $(001) \rightarrow (100)$ transition of $CO_2$ at wavelength $10.6 \mu m$. The corresponding optimum values like reservoir pressure and temperature and nozzle area ratio also have been predicted and presented in the form of graphs. The analysis predicts that employing of 2D- wedge nozzle results in higher gain values and the $CO_2-N_2-H_2O$ gas dynamic laser employing 2D-wedge nozzle is operationally the best laser system for which the optimum value as high as $3.1 m^{-1}$ gain can be obtained.