Impacts of laser pulse width and target thickness on laser micro-propulsion performance

In order to optimize the laser ablation performance of a micro-thruster with 1U dimensions, which employs a micro semiconductor laser, the impacts of pulse width and glycidyl azide polymer (GAP) thickness on thrust performance were researched. The results showed that with a GAP thickness of 200 μm, the single-pulse impulse (I) increased gradually with the increase in the laser pulse width from 50 to 800 μs, while the specific impulse (I_sp), impulse coupling coefficient (C_m) and ablation efficiency (η) all reached optimal values with a 200 μs pulse width. It is worth noting that the optimal pulse width is identical to the ignition delay time. Both C_m and η peaked with a pulse width of 200 μs, reaching 242.22 μN W^-1 and 35.4%, respectively. With the increase in GAP thickness, I and C_m increased gradually. GAP of different thicknesses corresponded to different optimal laser pulse widths. Under a certain laser pulse width, the optimal GAP thickness should be the most vertical thickness of the ablation pit, and the various propulsion performance parameters at this time were also optimal. With the current laser parameters, the optimal GAP thickness was approximately 150 μm, I_sp was approximately 322.22 s, and η was approximately 34.94%.