1D Gas Temperature Measurements by O2 Resonantly Ionized Photoemission Thermometry in a Mach 4 Ludwieg Tube

In this work, one-dimensional (1D) Oxygen-based Resonantly Ionized Photoelectron Thermometry (O-2 RIPT) technique is used for temperature measurements in a M-infinity = 4 flow. O-2 RIPT resonantly ionizes O-2 molecules via (2+1) Resonant Enhanced Multiphoton Ionization (REMPI) process; subsequent ionization via electron impacted avalanche ionization of molecular nitrogen produces fluorescence emissions from the first negative band of N-2 through photoemission deexcitation. The fluorescence emissions of the N-2 first negative band occur at Delta(v0), 390nm; Delta(v2), 425nm; Delta(v1), 430nm and are captured by a gated intensified scientific and used for temperature determination via a Boltzmann plot based on the direct relationship with the two-photon line strength. O-2 RIPT is used to characterize the free stream static temperature across a 50.8 mm (2 '') line, which is compared to isentropic calculations for the Mach 4 flow. Additionally, the thermal field associated with strong compression through a normal shock generated by a blunt 25.4 mm (1 '') diameter cylinder is measured.