A numerical investigation of atomic oxygen density in an inductively coupled plasma in O₂/Ar mixture

A numerical simulation of an inductively coupled plasma in an O ₂(<10%)/Ar mixture has been performed to investigate the production mechanisms and the spatial distribution of the atomic oxygen density. The O(³P) density is four times larger than that of O(¹D) and much larger than the metastable molecular oxygen O(a¹Δ _g) density at 100 mTorr. The dominant mechanism of O(³P) production is electron quenching of O(¹D) produced by dissociative excitation by electrons, and the net dissociation rate of O₂ is one order of magnitude smaller than that of electron quenching of O(¹D). However, quenching of O(¹D) and excitation of O(³P) are found to be competitive processes under the present conditions. Both electron and Ar metastable (Ar^*) density have the maxima at an O ₂ fraction of 1%, though Ar^* has little effect on the production of O(³P) and O(¹D) under the present high density plasma where Ar^* is quenched by high density electrons and consumed.