Celocity measurement of Arcjet plume with a diode-Laser absorption technique

摘要

A diode-laser absorption technique was introduced for measuring plume velocities of a 4 kW-class argon arcjet thruster. Intensities of an incident laser beam and transmissions through an argon discharge-tube, a Fabry-Perot etalon and the exhaust plume were simultaneously recorded with a digital oscilloscope. The amount of Doppler shift was derived from the difference in peak absorption frequencies between the discharge-tube and arcjet plume transmissions, using FP-etalon frequency-spacing data.