In order to optimize 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 was 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 (Isp), impulse coupling coefficient (Cm), and ablation efficiency (η) all reached optimal values with a 200 μs pulse width. It’s worth noting that the optimal pulse width is exactly the ignition delay time. Both Cm and η peaked with the pulse width of 200 μs, reaching 242.22 μN/W and 35.4%, respectively. With the increase in the GAP thickness, the I and the Cm increased gradually. The GAP of different thickness corresponded to different optimal laser pulse width. 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, the Isp was approximately 322.22 s, and the η was approximately 34.94%.

The micro-impulse generated by ablating aluminum target in double-pulse laser bursts with different interpulse delays was investigated using the torsion pendulum. The plasma plume was simultaneously visualized using high-speed photography to analyze the coupling mechanism of the ablation impulse. The experiment was carried out using the pulsed laser with the pulse width of 8 ns and the wavelength of 1064 nm. The experimental results show that the impulse with an interpulse delay of 60 ns is roughly 60% higher compared to that with no delay between the two pulses when the energy of both laser pulses is 50 mJ. Therefore, the double-pulse schemes could enhance the ablation impulse under certain conditions. The reason is that the ablation of the first laser pulse changes the optical properties of the aluminum target surface increasing the absorptivity. However, the ablation impulse is reduced at the time delay of 20 ns when the energy of both laser pulses is 100 mJ or 150 mJ. It can be concluded that the plasma produced by ablating aluminum of the first pulse shields the second laser pulse. To summarize, the experimental results show that different delay time in double-pulse scheme has a significant effect on the ablation impulse. The study provides a reference for the optimization of the parameters when the laser ablation propulsion with double-pulse scheme is applied in the fields of space debris removal, laser ablation thruster, and so on.