EVALUATION OF THE RATE CONSTANTS OF DISSOCIATIVE AND TERNARY RECOMBINATION REACTIONS OF ARGON IONS ON THE BASIS OF THE RESULTS OF BALLISTICEXPERIMENTS

Experimental data on the change in the electron density in the wake of a ballistic object traveling at velocities V-infinity = 3.4-4.9 km/s in argon at pressures p(infinity) = 30-100 Torr are processed and anal yzed. A reaction scheme is proposed which takes into account the recom bination of charged particles, processes of ionic conversion, and the excited states of the atom. The solution of the equations of a nonequi librium boundary layer for flow in the wake is used to formulate the i nverse problem of determining the rate constants for dissociative reco mbination Art Ar-2(+) + e --> Ar + Ar and ternary recombination Ar+ e + Ar -->Ar + Ar. The ''nearest-neighbor'' approximation is used to o btain theoretically an expression for the ternary recombination coeffi cient as a function of temperature and pressure. Numerous solutions of inverse problems and a comparison with experiments demonstrates the v alidity of the expression obtained for the ternary recombination coeff icient. It is shown that this expression is valid for moderate pressur es and complements the Pitaevskii: result for low pressures and the La ngevin result for high pressures. (C) 1997 American Institute of Physi cs.