BOLTZMANN-EQUATION ANALYSIS OF ELECTRON-MOLECULE COLLISION CROSS-SECTIONS IN WATER-VAPOR AND AMMONIA

Sets of electron-molecule collision cross sections for H2O and NH3 hav e been determined from a classical technique of electron swarm paramet er unfolding. This deconvolution method is based on a simplex algorith m using a powerful multiterm Boltzmann equation analysis established i n the framework of the classical hydrodynamic approximation. It is wel l adapted for the simulation of the different classes of swarm experim ents (i.e., time resolved, time of flight, and steady state experiment s). The sets of collision cross sections that exist in the literature are reviewed and analyzed. Fitted sets of cross sections are determine d for H2O and NH3 which exhibit features characteristic of polar molec ules such as high rotational excitation collision cross sections. The hydrodynamic swarm parameters (i.e., drift velocity, longitudinal and transverse diffusion coefficients, ionization and attachment coefficie nts) calculated from the fitted sets are in excellent agreement with t he measured ones. These sets are finally used to calculate the transpo rt and reaction coefficients needed for discharge modeling in two case s of typical gas mixtures for which experimental swarm data are very s parse or nonexistent (i.e., flue gas mixtures and gas mixtures for rf plasma surface treatment). (C) 1996 American Institute of Physics.