Variation of the Recombination Coefficient of Atomic Oxygen on Pyrex Glass with Applied RF Power

The wall recombination coefficient (γ) of atomic oxygen on a pyrex surface and O( 1 D) concentration in the downstream flow were measured in a radio-frequency (13.56 MHz) oxygen discharge in the applied power region of 200 W-2500 W. The NO 2 * continuum intensity was used to monitor the atomic oxygen. The γ varies from 1.1×10 -4 to 6.1×10 -5 , having a minimum value of 5.1×10 -5 at 700 W, at which point the glow discharge plasma changes to an arclike plasma. The mechanism of the transition of glow discharge plasma to arclike plasma and possible reasons for the inconstant γ are discussed in light of electron density, O( 1 D) concentration in the downstream flow, and the gas temperature.