cw laser gas heating in flowing argon was studied using emission spectroscopy. The local electron temperature was calculated from the 415.8-nm Ari line spectra ratio to the adjacent continuum emission. The two-dimensional temperature fields were utilized in the calculation of laser power absorption, beam refraction, radiative losses, and net thermal energy retained by the gas. The experiments were performed over a range of laser powers from 2.5 to 6.4 kW and flow velocities between 15 and 120 cm/s. The plasmas were determined to absorb as much as 78% of the incident laser energy at high powers and low flowrates. The calculations indicate that thermal energy retained by the gas is in excess of 35% of the incident energy at intermediate power levels and high flowrates. The results compare favorably with independent calorimetric and thermometric measurements as well as a numerical model. The primary conclusion is that laser propulsion appears feasible in that the earlier dynamic concerns have been shown to be nonexistent or circumventable.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)