Excited state distributions of hydrogen atoms and molecules in microwave discharge hydrogen plasma and effect of EEDF

We measured electron temperature and density by an electrostatic probe, and dissociation degree, number density of electronically excited states, and rot-vibrational temperatures of 2.45 GHz-microwave discharge hydrogen plasma at several torr in a cylindrical discharge quartz tube by spectroscopic observation. The electron temperature and density are found to be 3.0 - 4.5 eV and 7.0 times 10¹⁰ - 3.6 times 10¹⁰ cm^-3, respectively. From Fulcher-alpha band spectroscopy, we find that the vibrational temperature ranges from 0.65 to 0.74 eV, and the rotational temperature from 0.055 to 0.083 eV. The actinometry measurement shows that the dissociation degree of hydrogen molecule ranges from 4.0 to 5.0%. We calculate excited state population densities of hydrogen atoms using the hydrogen C-R model with measured data as input parameters. In the calculation, we find that the calculated population densities become about one order larger than those measured by OES if we assume Maxwellian EEDF. On the other hand, population densities with non-Maxwellian EEDF as a solution of the Boltzmann equation agree well with the experimentally measured values. In consequence, we confirmed significant effect due to non-Maxwellian EEDF on the excited states populations.