Investigation of the momentum coupling coefficient for propulsion by Nd:YAG laser at 1064 nm in atmospheric and water environment

The momentum coupling coefficient Cm for the laser propulsion in atmospheric and water environment is measured by the beam deflection method. The impulse generated by the final bubble collapse IB is discussed by the experiment and the numerical simulation for the laser propulsion in water. The results indicate that the experimental values of Cm in atmosphere agree well with the theoretical curve. IB has similar variation trend and range to the total momentum the propelled object obtained, which implies that the largest contribution to the propelling force in water is the final bubble collapse impact. Furthermore, Cm in water increases with the laser fluence first, and then decreases after the maximum due to the plasma shielding. The range of Cm in atmosphere and water are 3–10 dyn/W and 60–150 dyn/W, respectively, and the latter is 10 times more than the former under the same laser fluence.