Zhi-Yuan Zheng

Paper airplane propelled by laser plasma channels generated by femtosecond laser pulses in air

A long plasma channel, formed due to the dynamic balance between the nonlinear self-focusing and the plasma defocusing in the propagation of intense femtosecond laser pulses in air, is demonstrated to be able to continuously propel a paper airplane without complicated focusing optics. The maximum coupling coefficient generated by the plasma channel is found to be more than 8.5 dyne/W. In the plasma channel, the detonation wave generation with the air ionization is found to be the propulsive source.

Optimization of multiple filamentation of femtosecond laser pulses in air using a pinhole.

The robustness and prolongation of multiple filamentation (MF) for femtosecond laser propagation in air are investigated experimentally and numerically. It is shown that the number, pattern, propagation distance, and spatial stability of MF can be controlled by a variable-aperture on-axis pinhole. The random MF pattern can be optimized to a deterministic pattern. In our numerical simulations, we configured double filaments to principlly simulate the experimental MF interactions. It is experimentally and numerically demonstrated that the pinhole can reduce the modulational instability of MF and is favorable for a more stable MF evolution.

Spatial evolution of multiple filaments in air induced by femtosecond laser pulses.

The spatial evolution of plasma filaments in air induced by femtosecond laser pulses is investigated experimentally. Several major filaments and small scaled additional filaments are detected in the plasma channel. The complicated interaction process of filaments as splitting, fusion and spreading is observed. The major filaments propagate stably, and the small scaled additional filaments can be attracted to the major filaments and merged with them. The major filaments are formed due to the perturbation of initial beam profile and the small scaled filaments are mainly caused by the transverse modulational instability.

Application of laser plasma in propulsion

In laser plasma propulsion, laser interaction with multilayer target is investigated. The first layer of the target of fluid water, rigid glass, flexible polyimide as well as polyimide are tested It is found that the coupling coefficient of water confinement is higher and it is enhanced two orders compared with direct ablation. Through calculation the ablation pressure, higher coupling coefficient is attribute to the plasma confinement and impedance mismatch. Furthermore, the images of the polymers after ablation are observed.