Study on Rotational Relaxation in a Steady Hydrogen Plasma Jet Using Emission Spectroscopy

摘要

Rotational relaxation collision number of molecular hydrogen was experimentally determined using a steady plasma jet and emission spectroscopy. The plasma jet reached translational-rotational nonequilibrium by the strong free expansion at an orifice installed at the entrance of the test section, and translational-rotational relaxation occurred downstream of the orifice. Because the plasma jet was emissive, the translational and rotational temperatures could be directly measured using emission spectroscopy. The rotational relaxation collision number of molecular hydrogen Calculated based on these measured temperatures was 70-150 for the temperature range of 500-700 K. These results support two of the latest theoretical studies, thus demonstrating the validity of this methodology to determine the relaxation collision number.