Radial profiles of arcjet flow properties measured with laser-induced fluorescence of atomic nitrogen

Radial profile measurements of absolute atomic nitrogen density, temperature, and velocity using two photon laser-induced fluorescence in the NASA Ames Aerodynamic Heating Facility (AHF) are reported. Improvements in experimental technique and calibration procedure significantly reduced measurement uncertainties compared to previous efforts. The addition of a traversing system within the AHF test cabin permitted, for the first time, radial measurements of the three flow properties during a single arcjet run. Typical measurement uncertainties are 12% for absolute N density, 10-30% for temperature, and 3% for velocity. Details of the measurement technique, optical configuration, data analysis procedures, and results of two repeated demonstration runs in air/Ar flows are presented.