1 Arc Heated Wind Tunnel Flow Diagnostics using Laser- Induced Fluorescence of Atomic Species

Two-photon Laser induced fluorescence diagnostics system for atomic oxygen has been installed at the 750kW arc heated wind tunnel in JAXA in order to obtain velocity, translational temperature, and number density of atomic oxygen simultaneously. It was observed that the center of excitation wavelength is shifted in the shock layer. The Doppler shift due to the free stream velocity has a same order effect on the excitation wavelength. The translational temperature distribution was deduced from spectral broadening and the absolute atomic number density was obtained with a calibration technique by a reference xenon gas cell. Nomenclature a = effective branching ratio of the observed fluorescence transition Ap = cross sectional area of laser beam c = velocity of light, m/s Ep = laser pulse energy, J F(t) = normalized temporal profile of laser pulse h = Planck’s constant, Jxs I = electric current, A KL = laser calibration constan