Multiple equilibria in the oxygen positive column

The assumptions of straightforward moment models advanced to describe the equilibrium positive column in O₂ discharges are examined in a derivation from first principles. A particular such model employed by others is shown to lead, with the addition of consistent models for ionization, recombination, and mobility, to a nonlinear two-point characteristic value problem. This problem is shown to have two distinct physically acceptable solutions at certain O₂ pressures. In one of these solutions, ratios of the number densities of the charged species are constants across the column, while the ratios vary with radial position in the other.