Ground state and excited state H-atom temperatures in a microwave plasma diamond deposition reactor

Ground electronic state and excited state H-atom temperatures are measured in a microwave plasma diamond deposition reactor as a function of a low percentage of methane introduced in the feed gas and the averaged input microwave power density. Ground state H-atom temperature (T_H) and temperature of the H-atom in the n = 3 excited state (T_Hα) are obtained from the measurements respectively of the excitation profile by Two-photon Allowed transition Laser Induced Fluorescence (TALIF) and the H_α line broadening by Optical Emission Spectroscopy (OES). They are compared to gas temperatures calculated with a 1D diffusive non equilibrium H₂ plasma flow model and to ground electronic state rotational temperatures of molecular hydrogen measured previously by Coherent Anti-Stokes Raman Spectroscopy.