Cu HyBrID laser kinetics: optimization of HBr partial pressure and buffer-gas flow rate

Abstract

A detailed investigation into the dependence of the densities of the principal plasma species in the laser discharge on the buffer-gas operating parameters is reported. Simple expressions for the densities of the Cu, Br, and H species are derived by considering their major mechanisms for production and loss. These predict that the atomic Cu and Br densities are proportional to the HBr mass flow rate, whereas the density of H species (i.e., H and H 2) is proportional to the added HBr partial pressure. The theory agrees well with "Hook" method measurements of Cu density in a 25-mm bore diameter device; the Cu density increases approximately in proportion to the HBr mass flow rate, whereas it depends only weakly on the HBr partial pressure. Measurements of the fraction of Cu atoms excited by the discharge pulse, the rate of regrowth of the ground-state Cu density during the inter-pulse period, and the pre-pulse plasma impedance, are also explained in accordance with the theory. The results show that the plasma conditions for maximum laser output, which are remarkably similar to those of other "halogen enhanced" Cu lasers, can be achieved more directly by adjusting the overall buffer flow rate with the partial pressure of the added HBr fixed at 1-2 mbar. The theory is also useful for predicting optimum buffer-gas conditions for a wide range of Cu HyBrID laser dimensions and operating conditions.

Study on the purification of hydrogen bromide gas by fractional distillation technique and its effect on improvement of copper–hydrogen bromide laser performance

“…Using Eq. 29 In another study on CuBr laser with HBr and H 2 additives, it was concluded that the optimal conditions of gas mixtures are necessary for improving the laser performance. Based on this estimation and using Eq.…”

“…Based on this estimation and using Eq. 29 In the case of undistilled HBr gas, the injected gas components consist of HBr molecules and their dissociation products, i.e., H 2 and Br 2 . Figure 4(a) and 4(b) shows the variation of active electrical power and discharge resistance.…”

“…This could be for three reasons. 29 So the possibly reduced ground-state copper density along with slower discharge pulse rise time [∼80 ns versus ∼60 versus Fig. 15,16 Second, the excess concentration of hydrogen and bromine in Cu-HBrL discharge (with undistilled HBr gas) might have led to depletion/locking of ground-state copper density in the form of CuBr and CuH (i.e., Cu þ Br∕H → CuBr∕ CuH).…”

Compact and efficient kinetically enhanced copper-vapor lasers of high (100-W) average power

“…These studies have demonstrated, however, that eff icient laser operation with good spatial characteristics is obtained from KE-CVLs at simultaneously high specific input-output powers and average output powers. Because of their similar plasma composition and performance characteristics, 17 Cu HyBrID lasers and CuBr lasers with H 2 additive are also likely to generate similar performance, provided that the optimum plasma mixture can be maintained at the requisite input power levels.…”