Measurement of Main Characteristics of a Glow Discharge by Surface Waves Resonance and Optical Emission Spectroscopy

A non-invasive voltage standing wave ratio (VSWR) method for electron density measurement in the surface layer of mercury plasma glow discharge is studied. The method is based on determination of resonant frequencies between the plasma layer and the radio frequency signal by the unit standing wave ratio (SWR) combined with the calculation of the dielectric permittivity and Langmuir frequency. A simplified fluid plasma model is developed and validated by emission spectroscopy for comparing the method’s results. The method can be used for measuring electron number density in plasma volume.