VUV spectroscopic diagnostics of the vibrational temperature to the ground state of hydrogen molecules in recombination plasma

The vacuum ultraviolet (VUV) spectroscopic method has been evaluated for measuring of the vibrational temperatures T$_{vib}$ of H$_{2}$ to the electronic ground state in hydrogen recombination plasma. This is inferred from the comparison of simulated Lyman, Werner spectra for H$_{2}$ taking into account radiation trapping effects with measured VUV spectra in the range from 90 to 150 nm. T$_{vib}$ of H$_{2}$ is around 4000-5000K in hydrogen plasma at the discharge current of 50 A and electron temperate of 10 eV. With increasing the gas pressure, T$_{vib}$ decreases and remains constant at 1000 K in the recombination plasma.