Impulse measurement of laser induced ablation in a vacuum

An impulse measurement system based on a simple pendulum is newly developed. The system has a resolution of 10^-7 Ns for ablation events induced by a single laser at a pulse rate of 2 Hz or less. For ablation events at 10 Hz and above, the system can record the impulse as an average force. The impulse generated by a Nd:YAG pulse laser irradiating a 7075 aluminum alloy is investigated in vacuum. The impulse arises at 3 J/cm² and the momentum coupling factor, C_m, plateaus at approximately 20 μNs/J over a range of 5 to 50 J/cm² without producing a plasma shielding effect. C_m is characterized by only fluence independent of pulse width in the range of 10 to 20 ns. This result indicates that it should be feasible to deorbit a 150 kg abandoned satellite at an altitude of 1200 km using a chaser satellite equipped with a 100 W laser.