Experimental Investigation of Axial and Beam-Riding Propulsive Physics with TEA CO_2 laser

摘要

A twin Lumonics K922M pulsed TEA CO_2 laser system (pulse duration of approximately 100 ns FWHM spike, with optional 1 μs tail, depending upon laser gas mix) was employed to experimentally measure both axial thrust and beam-riding behavior of Type #200 lightcraft engines, using a ballistic pendulum and Angular Impulse Measurement Device (AIMD, respectively. Beam-riding forces and moments were examined along with engine thrust-vectoring behavior, as a function of: a) laser beam lateral offset from the vehicle axis of symmetry; b) laser pulse energy (～12 to 40 joules); c) pulse duration (100 ns, and 1 μs); and d) engine size (97.7 mm to 161.2 mm). Maximum lateral momentum coupling coefficients (C_M) of 75 N-s/MJ were achieved with the K922M laser whereas previous PLVTS laser (420 J, 18 μs duration) results reached only 15 N- s/MJ-an improvement of 5x. Maximum axial C_M performance with the K922M reached 225 N-s/MJ, or about ～3x larger than the lateral C_M values. These axial C_M results are sharply higher thanthe 120 N/MW previously reported for long pulse (e.g., 10-18 μs) CO_2 electric discharge lasers.