Impulse and Plasma Plume Generated By Ablating Aluminum Target with Nanosecond Laser in Double-Pulse Configuration

Abstract

For laser ablation propulsion, the enhancement of the impulse is very challenging to realize without increasing the laser energy. In this paper, the enhancement of the impulse in vacuum is achieved by laser ablation in double-pulse mode. The impulse produced by irradiating the aluminum target for different energy combinations in double-pulse mode was measured with the torsion pendulum. The plasma plume was observed at the same time by fast photography to analyze the cause of the impulse characteristics. The effect of the energy combinations for double-pulse mode on the ablation impulse was investigated at typical interpulse delay time. When the delay time between the pulses is set to 80 ns, the maximum impulse is increased by approximately 11% compared to that of the single-pulse mode at the same total energy, wherein the energy of the first pulse is 125mJ in total energy of 200mJ. Therefore, the enhancement of the impulse can be achieved by choosing the suitable energy combination in the double-pulse configuration. However, when the time delay is 300ns, the difference in energy combinations has little influence on the impulse. The results reported here provide guidance for the application of laser ablation propulsion in space.