Impulse Vector Characteristics of Laser Ablation Thrusters

Abstract

This paper proposes direct focusing of repetitive high-power laser pulses on an arbitrary surface of a vehicle in the atmosphere to generate a blast wave at each pulse and push the vehicle along an impulse or thrust vector. Fundamental research was conducted on the interaction between a focused high-power laser pulse or blast wave and a surface with arbitrary curvatures. The characteristics of the impulse or thrust vector generation on the surface were numerically simulated. For simplicity, some fundamental shapes of the surface or vehicle were assumed for the simulation (i.e., planar and semicircular bodies) to examine shock-surface interactions. The impulse vector characteristics were also investigated experimentally. The results showed that the composition of the impulse vector (or each component) reached about 90% of the total impulse in the initial 10 s. In this duration, a significant high-pressure region induced by the shockwave was localized near the laser irradiation spot; it acted on the surface vectors to induce a primary thrust. Based on these results, the directions of impulse vectors are primarily determined by the local surface vectors of the laser irradiation spots. Nomenclature r = Model radius t = Time = Nozzle angle = Laser irradiation spot angle