Dissociation efficiency of electron-beam-triggered discharges for initiating atmospheric-pressure H2-F2 lasers

Abstract

Time-resolved uv absorption measurements of the rate of F2 disappearance have been compared with a theoretical pulsed chemical laser code to infer electrical dissociation efficiencies of electron-beam-irradiated discharges. The results indicate that a 400-keV 50-nsec e-beam of ~ 10 A/em' dissociates approximately 0.3% of the reactants initially present in dilute F,/H, mixtures, producing four chain carriers per ionizing collision. With the addition of a discharge field at 80% of the self-breakdown limit, initial reactant dissociation increases to approximately 1.1 %, corresponding to 15 chain carriers per ionizing event and a dissociation efficiency of 7.5%. An earlier analytical plasma model of reactant dissociation that has been generalized to account for the presence of Ar and H2 suggests that heating of the negative ions of fluorine, leading to electron detachment in heavy-particle collisions and direct electron-impact dissociation of reagents by slow electrons become dominant mechanisms with the application of a strong undervolted field. In general, the approximate plasma analysis is shown to yield results that are in qualitative agreement with the experimental data.

Pulsed Chemical Laser with Variable-Pulse-Length Electron-Beam Initiation and Magnetic Confinement.

“…By comparison of the experimental rate of F 2 disappearance with theoretical 3 pulsed HF laser code predictions, we recently reported the efficient production of chain carriers by an electron beam operating at relatively low current densities. 4 The present investigation extends the work of earlier investigators to longer electron-beam pulse lengths and lower current densities. We seek to establish scale size limitations for transversely pumped electronbeam-initiated chemical lasers and to increase the permissible limit of laser pulse repetition frequency (as constrained by anode foil heating).…”

Pulsed chemical laser with variable pulse-length electron-beam initiation and magnetic confinement

“…4 The present investigation extends the work of earlier investigators to longer electron-beam pulse lengths and lower current densities. We seek to establish scale size limitations for transversely pumped electronbeam-initiated chemical lasers and to increase the permissible limit of laser pulse repetition frequency (as constrained by anode foil heating).…”

Modelagem dos processos químicos em plasmas de misturas gasosas usadas na corrosão de silício. Parte 2: SF6 / O2

“…Como base para este trabalho foram utilizados os modelos de Ryan e Plumb 10,17 , Jorné e colaboradores 19 e Amoroux e colaboradores 20 , que são os mais recentes para as condições escolhidas, assim como outros dados cinéticos disponíveis na literatura 14,[23][24][25][26][27][28] . Foram realizadas as modificações necessárias nos modelos anteriores, como será posteriormente apresentado, para se obter a melhor descrição possível para este problema.…”