Analysis of Shock Layer Radiation in Vacuum-Ultraviolet Region for HAYABUSA Return Conditions

Abstract

This paper presents the shock layer radiation measurement in VUV region by the shock tube experiment. The measurement system of the VUV spectroscopy is newly developed at the test section of the shock tube. The calibration of the measurement system is conducted in order to obtain the absolute radiation intensity of the measured spectrum. The spectrum in VUV region becomes more intense than that in UV region with increasing the shock velocity. On the other hand the spectrum in UV region is almost same with increasing the shock velocity. Spectrum analysis shows the electronic excitation temperature is higher than the vibrational temperature just behind a shock wave, contradicting the assumption of the twotemperature model. The electronic excitation temperature is obtained behind a shock wave by the relative line intensity method to the line spectra of atomic nitrogen and the spatial distribution of the electronic excitation temperature is obtained. The result shows the measured electronic excitation temperature is higher and nonequilibrium with the vibrational temperature, consisting the result of the spectrum analysis.