Plasma study of a moly-oxide-argon discharge bulb

A mercury-free molybdenum-oxide-argon (Mo-O-Ar) electrodeless discharge is described with potential application to plasma lighting. The low-pressure metallic plasma is a nonequilibrium discharge capable of producing visible light directly with an efficacy of ∼40 lm/W. The Boltzmann equation is solved with a limited set of chemical kinetics to provide a zero-dimensional model of the discharge. Model results indicate a transition in the power transfer from Ar to Mo as the partial pressure of Mo is increased. This feature is qualitatively similar to an intense transition from weak to strong visible emission observed in the Mo-O-Ar discharge with increasing power. The Mo partial pressure at the transition is estimated from an actinometry approach including a collisional radiative model of the plasma. The calculated electron density is also compared with interferometric data.