Measurement of Highly Rarefied Nonequilibrium Flows by REMPI

Abstract

REMPI (Resonantly Enhanced Multiphoton Ionization) is a powerful optical tool for measurements of highly rarefied gas flows because of its high sensitivity and ability to measure nonequilibrium among translational and internal energy, thus it will be a powerful tool for measurements of reflected molecules in gas-surface interaction experiments. In this paper, we proposed the temperature measurement technique by 2R+2 N_2-REMPI for measurements of rarefied gas flows in gas-surface interaction experiments. To propose a method of Boltzmann plot using the spectral lines of both O and P branches, electronic transition dipole moments in Honl-London factors are determined experimentally form the relative line strength of O and P branches. Then an effect of an experimental noise on a rotational temperature measured by the Boltzmann plot becomes smaller because the number of the lines used for the plot increases.