Laser-induced-fluorescence characteristics of a helium arcjet flow

Laser-induced fluorescence is used to characterize the axial velocity and temperature field at the exit plane of a low-power helium arcjet. Two cases were examined, one in which the mass-flow rate was changed at a constant current, and the other where the current was changed at a constant mass-flow rate. At constant mass-flow rate, the velocity scales with the increase in power. At constant current, a higher specific energy results in an unexpected lower mean exit velocity. The temperature profiles show that the nozzle-wall temperature is greater than the mean exit temperature. Along the axis of the arcjet, these measurements indicate the presence of a shock less than one nozzle diameter downstream of the exit. Received: 10 July 2002 / Published online: 22 November 2002 RID="*" ID="*"Corresponding author. Fax: +1-650-723-1748, E-mail: qwalker@stanford.edu