Diagnostics of an argon arcjet plume with a diode laser

The diode-laser absorption technique was applied for simultaneous velocity and temperature measurements of an argon plume exhausted by an arcjet. The Ar I absorption line at 811.531 nm was taken as the center absorption line. The velocity and the temperature were derived from the Doppler shift in th e absorption profiles and the full width at half-maximum of the plume absor ption profile, respectively. From the measured plume velocity and temperatu re, the total enthalpy of the exhausted plume, the thrust efficiency, and t he thermal efficiency of the arcjet were derived, and the performance of th e arcjet was examined. The results are demonstrated to agree with results d erived by other methods, and the technique can be applied to the measuremen t of other arcjet systems without much modification. (C) 1999 Optical Socie ty of America.