Efficient e-beam and discharge initiated nonchain HF(DF) lasers

Abstract

The spectral and amplitude-temporal parameters of HF (DF) lasers pumped by nonchain chemical reactions initiated by radially convergent or planar e-beams and self-sustained discharge were studied. Intrinsic efficiency of the HF lasers up to ∼10% was obtained for both excitation methods. It was shown that the high efficiency of an e-beam-initiated HF laser may be attained as a result of the simultaneous formation of atomic and molecular fluorine and of the participation of F₂ in population inversion. A laser pulse has a complex profile caused by the successive generation of P-lines and the overlap during the radiation pulse of both the rotational lines of the same vibration band and of individual vibration bands. Experimental conditions providing high intrinsic efficiency of a discharge nonchain HF (DF) laser are determined. Intrinsic efficiency of HF and DF lasers up to η_in ∼ 10% and 7%, respectively, is obtained using excitation by inductive and LC generators in the SF₆-H₂ (D₂) mixtures. High discharge uniformity obtained with the use of special shaped electrodes along with uniform UV preionization is a key parameter for improving the intrinsic efficiency of discharge HF (DF) lasers. It was found that in this excitation condition, output spectra of the HF laser significantly widen and cascade laser action on some rotational lines of the vibrational transitions of HF molecules ν(3–2) → ν(2–1) → ν(1–0) is observed. This can explain the high intrinsic efficiency obtained. Specific output of the discharge HF laser over 8 J/L (140 J/L×atm) and total laser efficiency η_t ∼ 4.5% were achieved. For the discharge DF laser, specific output and total efficiency were as high as 6.5 J/L and 3.2%, respectively.