Investigation of Neon RF Discharge by Means of Refined Collisional-Radiative model
| Authors | |
|---|---|
| Year of publication | 2008 |
| Type | Article in Proceedings |
| Conference | Programme & Abstract Book of 23rd Symposium on Plasma Physics and Technology, Prague, Czech Republic, 13.-19.June 2008 |
| MU Faculty or unit | |
| Citation | |
| Field | Plasma physics |
| Keywords | rf discharge; collisional-radiative model; optical emission spectroscopy; neon |
| Description | A recently developed collisional-radiative (c-r) model for neon discharge was used to investigate the plasma properties of a capacitively coupled RF (13.56 MHz) discharge in neon. By means of c-r model, population of thirty excited states of neon atom and therefore optical emission spectrum for a given electron distribution function was determined. The discharge was studied by optical emission spectroscopy. By comparison of measured and calculated optical emission spectra on the basis of least-squares method the electron temperature or electron density was determined. The developed collisional-radiative model was refined in order to describe the studied plasma more correctly. Some important processes (as e.g. excitation transfer between 3s levels of neon atom induced by electron impact), were newly incorporated in the presented calculations. A 1/y-weighted sum of squares was used in the comparison of the spectra. Moreover, the model was modified in order to determine the emission coefficient of unit plasma volume in absolute values. Since in previous work the measurement of relative intensities was found to be insufficient for determination of electron density, an absolute intensity measurement was performed. Jobin Yvon Horiba Triax 550 spectrometer, equipped with CCD camera, was calibrated by Oriel Tungsten-halogen filament lamp. The radiation of a defined narrow cylindrical region was taken out by means of two iris diaphragms, mounted at their common axis in front of the optical fibre. The temporal development of the plasma, important for the determination of real radiation time, was studied by Jobin Yvon Horiba FHR 1000 spectrometer with ICCD camera. The sensitivity of the model, as well as the influence of the newly incorporated processes on the results was evaluated. Assuming Maxwellian electron distribution function, without absolute intensity calibration the model is insensitive for electron temperatures below 4 eV. |
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