Thomson scattering diagnostics of glow discharge plasmas produced in Raman active gases

In Thomson scattering measurements of processing plasmas, rotational Raman scattering light from molecules sometimes overlaps the observed spectra. In order to solve this problem, a new method is proposed. This method involves separating the Thomson scattering component from the Raman scattering component by utilizing differences in the scattering characteristics depending on scattering wavelength and scattering geometry. By using this method, electron densities and electron temperatures of a microwave discharge plasma produced in a H-2/CH4 gas mixture at a moderate pressure were successfully measured for the first time.