Effect of gain length on hydrogen fluoride chemical laser amplifier performance

Abstract

An amplifier performance model that predicts a device's amplifier performance given the device's oscillator performance as a function of reflectivity was developed. Excellent agreement between single pass model predictions and single pass experimental data was obtained. The model was used to predict amplifier performance as the gain length was scaled from 0.3 to 4 m for three different lasers. When the amplifier performance curve is plotted in terms of nondimensional powers font vs ft n , gain length dependent, device independent curves result. The nondimensional amplifier performance curve showed that, with a single pass amplifier, one 0.3-m oscillator may be able to drive three amplifiers and one 4-m oscillator might be able to drive eight amplifiers. These results, which are independent of device, are sensitive to the oscillator power vs reflectivity performance curve in the 0-20% reflectivity range.AR g go / I s L e L g P in ou t am /? eff Nomenclature = amplification ratio, P ou t/^m = gain coefficient, cm" 1 = zero power or small signal gain coefficient, cm" 1 = radiation flux, W/cm 2 = saturation radiation flux, W/cm 2 = thickness of the mixed flow ( = L g when fully mixed) = geometric gain length = input power to the amplifier = P out , output power from the amplifier = output power from the oscillator = effective reflectivity of the oscillator's resonator reflectivity of the outcoupler mirror times the reflectivity of the feedback mirror = coordinate in the direction of the optical axis = nonsaturable distributed loss, cm" 1 = P0ut ~ ^in = power/nozzle bank exit area, W/cm 2 = nondimensional input power (input power to the amplifier/output power from the oscillator at z a eff = f out = nondimensional output power (output power from the amplifier /output power from the oscillator at # eff -20%)