A microwave plasma source of neutral nitrogen atoms

A microwave source of nitrogen atoms is described. Atom production in the discharge bulk ( mixtures) and atom losses in the flowing afterglow are analysed. The rotational temperature is measured by emission spectroscopy along the discharge (0 - 0 band of the second positive system) and the afterglow (first positive or first negative system depending on the afterglow type). Depending on the experimental conditions ( concentration), two types of flowing afterglow can exist. At high percentage, a `pink' afterglow occurs upstream of the classical `Lewis - Rayleigh' afterglow. An NO titration method provides the atom concentration downstream of the discharge. Then, the N atom transport is explained from a simple model accounting for the energy characteristics of the plasma (obtained by the microwave interferometry methods) and the kinetics.