Evaluation of oxygen species during E-H transition in inductively coupled RF plasmas: combination of experimental results with global model.

Abstract: Inductively coupled RF plasmas (ICP) in oxygen at low pressure have been intensively studied as a molecular and electronegative model system in the last funding period of the Collaborative Research Centre 24 “Fundamentals of Complex Plasmas”. The ICP configuration consists of a planar coil inside a quartz cylinder as dielectric barrier which is immersed in a large stainless steel vacuum chamber. In particular, the E-H mode transition has been investigated, combining experimental results from comprehensive plasma diagnostics as input for analytical rate equation calculation of a volume averaged global model. The averaged density was determined for electrons, negative ions O−, molecular oxygen ground state O2(X3Σg−) and singlet metastable state O2(a1∆g) from line-integrated measurements using 160 GHz Gaussian beam microwave interferometry coupled with laser photodetachment experiment and VUV absorption spectroscopy, respectively. Taking into account the relevant elementary processes and rate coefficients from literature together with the measured temperatures and averaged density of electrons, O2(X3Σg−) and O2(a1∆g) the steady state density was calculated for O(3P), O2(b1Σg+), O(1D), O(1S), O3, O−, O2−, and O3−, respectively. The averaged density of negative ions O− from the rate equation calculation is compared with the measured one. The normalized source and loss rates are discussed for O(3P), O2(b1Σg+) and O−. Graphical abstract: <graphic></graphic> [ABSTRACT FROM AUTHOR]