Temperature and Density Measurements on Hypersonic Wind Tunnels Using Laser Induced Fluorescence of NO, Including a Study of NO Spectroscopy Using a Novel Heated Cell

Abstract

With the aim of being able to determine temperatures in high enthalpy flows, NO LIF measurements were carried out on a novel heated cell, on two other wind tunnels (arc-heated wind tunnel LBK in Cologne, and shock tunnel TH2 in Aachen), and on the high enthalpy shock tunnel HEG in Goettingen. In an exhaustive study of NO excitation and fluorescence spectroscopy in the tuning range of the ArF excimer lasers (193 - 4 nm), using the specially constructed heated calibration cell at temperatures of 1200 K, over 400 transitions could be unambiguously assigned. Anomalous line intensities for the satellite branches were observed, and discrepancies for measured and calculated line positions for the (3,0) band were tentatively assigned to a perturbation of the A(3) level by an excited predissociative electronic state. Suitable line pairs for determination of temperatures in high enthalpy flows were identified.