Laser-induced fluorescence of the Balmer–alpha (Hα) transition of atomic hydrogen was performed within the nozzle of a 1-kW class radiatively cooled arcjet thruster operating on hydrogen and synthesized-hydrazine propellants. Axial velocities were determined from the Doppler shift of the Hα line center relative to a stationary reference, whereas translational temperatures and electron number densities were determined from a line-shape analysis of the Hα transition. The results are compared with a numerical model and indicate excellent agreement with the velocities, as well as temperatures near the nozzle exit. There are discrepancies, however, in the temperatures far upstream of the exit and in the electron densities, suggesting needed improvements in the modeling of the recombination chemistry.
© 1998 Optical Society of America
P. Victor Storm and Mark A. Cappelli, "Arcjet Nozzle Flow-Field Characterization by Laser-Induced Fluorescence," Appl. Opt. 37, 486-495 (1998)