The electron beam diagnostic of the clustered supersonic nitrogen jets
Journal of Physics, Conference Series
Efficient chemical oxygen -iodine laser with a high total pressure of the active medium M V Zagidullin, V D Nikolaev, M I Svistun et al. -Molecular tagging velocimetry in nitrogen with trace water vapor Carl A Hall, Marc C Ramsey, Darin A Knaus et al. -Emission and laser-induced fluorescence measurements in a supersonic jet of plasma-heated nitrogen L M Cohen and R K Hanson -This content was downloaded from IP address 22.214.171.124 on 23/07 Abstract. Axial and radial distributions of the
... utions of the rotational temperature and density of N2 molecules in supersonic nitrogen jets formed with conic nozzles (critical diameters dcr of 0.17 and 0.21 mm) were studied using the electron beam fluorescence technique at stagnation pressures P0 of 0.1-0.6 MPa. A rotational temperature Tr, equaling a gas temperature Tg owing to fast RT relaxation, was obtained using the rotational line relative intensity distribution in (0-1) vibrational band of the N2 first negative system. Gas density profiles in the jets were obtained using the integral intensity of the band. It is found, Tr at the nozzle outlet is of the order of a few tens of Kelvin and at further expansion Tr drops up to 15-20K at distance of (100-200) dcr. The gas temperature and density distributions in the studied supersonic nitrogen jets are not similar to the isentropic distributions. It is shown that the lower is the stagnation pressure the faster the gas density and temperature decrease with distance from the nozzle. Increase in P0 leads to elevating Tg in the jets. A reason for this effect may be cluster formation in the jets. Estimations of cluster mean sizes in the jets using Hagena's parameter show presence of large clusters (M≥200) at P0=0.4-0.6 MPa.