Improved performance of a double discharge initiated pulsed HF chemical laser

Abstract

Operation of a pulsed HF chemical laser initiated by electric discharge is reported. Uniform transverse capacitive discharge through high-pressure mixtures of SF6 and H2 is effected by the use of a double discharge. For the mixture SF6, H2, He (250, 20, and 280 Torr, respectively) laser output of more than 1 J per pulse with 4% electrical efficiency from an active volume of 0.06 1 has been achieved. Pulse shapes of the different transitions, spectrum measurements, and SF6 decomposition rate are reported.

Efficient nonchain discharge HF and DF lasers

“…The radiation pulse begins ∼100 ns later the gap breakdown, its intensity exponentially decreased with the characteristic time t Int ∼500 ns for integral pulse and t P1 ∼200 ns for radiation on theν 1 band. Distribution of energy over the vibrational bands Q(ν1):Q(ν2):Q(ν3)=7:3:1 drastically differs from those presented in the available papers 1,7,10,14 . Therewith about 60% of total laser output was emitted on P 1 (7) and P 1 (8) lines.…”

“…One of the reasons limiting the efficiency is development of discharge non-uniformities 6 . Additions into gas mixtures of the non-chain lasers or replacement of H 2 (D 2 ) with hydroor deuterocarbons 7,8 along with development of small-scale roughness on the electrode surface 9 increase discharge stability. In some cases increase of the preionisation intensity improves the laser efficiency 2,10 .…”

Self-sustained volume discharge in mixtures of SF6 with hydrocarbons, hydrogen and deuterium for non-chain HF(DF) lasers

“…Chemical reactions in SF 6 :Н 2 (D 2 ) gas mixture can only be initiated through SF 6 molecules dissociation by an external energy source with formation atomic fluorine. The best non-chain HF laser parameters are realizable in a self-sustained volume discharge (SSVD) in SF 6 :Н 2 or SF 6 :C 2 Н 2 working mixtures [5][6][7][8] subjected to a high-voltage. Due to the strong electronegativity of SF 6 , electron multiplication in the SSVD plasma occurs at an extremely high critical reduced electric field (Е/N) cr ≈ 360 Тd (1 Тd = 10 −17 V • cm 2 ), and in this case the average electron energy approaches 10 eV and more than 80% of the absorbed electric energy is spent for SF 6 dissociation to form atomic fluorine [9,10].…”

On Functions of Several Complex Variables That Are Separately Meromorphic

“…A primary requirement for high-quality pulsed gas laser output is, however, production of a stable and uniform discharge, but the electronegativity of SF6 makes the maintenance of such a discharge difficult. The problem may be overcome by use of double discharge or pre-ionisation techniques in conjunction with Rogowski profiled metallic electrodes (Voigner andGastaud 1974, Wlodarczyk 1978). Such methods, however, tend to introduce problems associated with timing between the two electrical discharges and almost invariably place heavy demands on the amount of general maintenance that must be undertaken on the laser amplifier in an operational situation.…”