Plasmas afterglows with N2 for Surface Treatments

Abstract

This book is focused on the production of plasma active species containing N₂ which are molecules in electronic, vibrational and rotational states and dissociated atoms or radicals. The method of NO titration of N and O-atoms density and that of the percentage of afterglow resulting of N-atom recombination are detailed. The relevant kinetics equations in the afterglow and the intensity ratio method to obtain the radiative species density from that of N-atoms are elucidated. By this method, it is obtained the densities of O, H and C-atoms, of N₂(A) and N₂(X,v>13) metastable molecules, NH, NO and CN radicals. The plasmas and afterglows were obtained by a microwave supply at reduced gas pressure in the Montreal and Toulouse Univ. and at atmospheric gas pressure in the Orsay, Pau and Toulouse Univ. Interestingly enough, densities of N-atoms and N₂(A) metastable molecules in the afterglow regions, however, are measured to be very similar with each other. Production of active species is studied in N₂ and in N₂-O₂ afterglows of electrical discharges at low and atmospheric gas pressures. They are produced in microwave discharges in a large range of gas pressures from a few Torr to 100 Torr and in corona discharges at atmospheric gas pressure. The processes of bacteria decontamination in N₂-O₂ afterglows are described for low pressure microwave and atmospheric pressure corona discharges. Transmission of N-atoms through porous membranes is studied at medium pressure (10-100 Torr) in microwave afterglows.