Design Engineering Of Large High-Pressure Gas Laser Amplifiers

The creation of a population inversion in large-volume high-pressure gas via an electrical discharge poses numerous engineering problems, not only concerning details of various components, but also in overall system performance or optimization. The Laser Division at Los Alamos has developed a base of engineering data and computational techniques which addresses the engineering design problems for our short-pulse, large, high-pressure CO2 amplifiers. The various aspects of the problem considered individually and in total are: 1. Selection of gas mixture for specific application; 2. Physical specifications (size, pressure, voltage, current, etc.) of discharge to achieve desired energy output. This involves the use of computer codes to account for gas kinetics relevant to the production of a population inversion and energy-extraction codes; 3. Specification of energy supply and delivery system to provide power to the discharge. This involves computer codes to predict discharge current and voltage waveforms, taking account of various circuit elements (capacitors, inductances, and transmission lines) as well as the nonlinear character of the discharge; 4. Nonuniformities in discharge and population inversion resulting from magnetic field effects, finite geometry, etc. This involves computer codes which consider electron trajectories in the high-pressure gas in the presence of electric and magnetic fields as well as the nonlinear characteristic of the discharge. The calculational techniques have been used to design a prototype amplifier for the Los Alamos 100-kJ Antares system. The prototype was built and the design calculations confirmed by measurements.