1428 超希薄気体流における温度非平衡現象の解析  [in Japanese] An analysis of nonequilibrium of temperatures in highly rarefied gas flows  [in Japanese]

In highly rarefied gas flows, there appear deviation of rotational energy distribution from the Boltzmann distribution. In this study, to analyze the nonequilibrium phenomena, we applied 2R+2 N_2-REMPI to the measurement of rotational energy distributions along the axial center line in a supersonic free molecular flow of nitrogen. As a result, strong nonequilibrium in the rotational energy mode has been found in the flow. The Boltzmann plot obtained from the measured REMPI spectra cannot be fitted by one line, revealing the non-Boltzmann distribution of the rotational energy. The transition from the equilibrium to the nonequilibrium is also discussed by showing the dependence of the rotational energy distribution on the distance from the nozzle exit in the flow.