Dissociation efficiency of electronhyphen;beamhyphen;triggered discharges for initiating atmospherichyphen;pressure H2hyphen;F2lasers

摘要

Timehyphen;resolved uv absorption measurements of the rate of F2disappearance have been compared with a theoretical pulsed chemical laser code to infer electrical dissociation efficiencies of electronhyphen;beamhyphen;irradiated discharges. The results indicate that a 400hyphen;keV, 50hyphen;nsec ehyphen;beam of A/cm2dissociates approximately 0.3percnt; of the reactants initially present in dilute F2/H2mixtures, producing four chain carriers per ionizing collision. With the addition of a discharge field at 80percnt; of the selfhyphen;breakdown limit, initial reactant dissociation increases to approximately 1.1percnt;, corresponding to 15 chain carriers per ionizing event and a dissociation efficiency of 7.5percnt;. An earlier analytical plasma model of reactant dissociation that has been generalized to account for the presence of Ar and H2suggests that heating of the negative ions of fluorine, leading to electron detachment in heavyhyphen;particle collisions and direct electronhyphen;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.