Plasma Creation and Evaluation of Flight Performance on Multi-parabola Laser Thruster Propelled by Repetitive Pulses

Laser propulsion systems are attracting attention as a new launch method in space development. An intense laser is irradiated onto the vehicle from the ground and focused by a mirror to ignite a plasma. The plasma then absorbs an energy of the succeeding laser, generating blast waves that propel the vehicle. In this system, the vehicle must have the ability to fly while following the axis of the incident beam. Myrabo successfully launched the lightcraft-type vehicle to an altitude of 71 m in a free-flight experiment. However, the vehicle has a tendency to tilt with respect to the laser axis, and in fact, in that experiment, the vehicle was rotated at 10,000 rpm to obtain a gyroscopic effect, which is far from being practical. The multi-parabola thruster has been proposed by Kogushi et al. as a vehicle with better flight performance than the lightcraft. In this study, we conducted breakdown experiments of the multi-parabola thruster using repetitive pulses laser to observe an ignition process of the dense plasma and to evaluate its flight performance. Camera imaging revealed that the plasma was successfully created when the laser beam was focused by the parabolic mirror, which repeatedly supplied propulsive forces to the vehicle and contributed to an increase in flight altitude.