Research Flyer Initiating The Energy Efficiency Of The Laser Drive System

Laser-driven miniflyer priming system is characterized by high precision control in time, prompt initiation, anti EMI and reliable initiation, which meets the developments of insensitive explosives. It’s one of the main research directions for advanced initiators in recent years. As a conversion part of laser-driven miniflyer priming system, the flyer plays a role in converting laser energy into kinetic energy, and brings about shock initiation of explosives in high speed. Due to low transmission and utilization efficiency of laser, it’s difficult to apply this system in practice. Improving and bettering the flyer structure is a key technology in increasing energy efficiency. This paper mainly discusses the flyer part in the priming system through using the theoretical and experimental methods. Multi-flyer applied in the priming system is benefit for increasing the velocity of flyer、impact pressure and energy efficiency.(1) By calculating the energy loss during the process of laser-driven flyer, a method for analyzing the energy generated by flyer with different velocities was proposed. With the method, the feasibility of using multi-flyer to enhance the energy efficiency of the priming system was analyzed, and the influences of absorption layer and insulator layer in multi-flyers were discussed. The critical velocity value, at which the flyer could detonate1.60g·cm-3PETN with shock waves, had been calculated through the p2τ criterion. LS-DYNA program had simulated the effect of detonating1.60g-cm-3PETN with laser-driven miniflyer system.The theoretical analysis provides a new way for simulating the velocity and analyzing the energy efficiency of laser-driven miniflyer system, and provides guidance for improving the structure of small-size flyers.(2) On the basis of theoretical analysis, related performances of flyers were studied with the aid of Scanning Electron Microscopy (SEM), Photoelectronic hybrid average velocity testing system, PVDF pressure gauge and PDV high-speed testing system.The multi-flyers were prepared with the ion beam evaporation and the magnetron sputtering; a preliminary discussion about the influences of these two methods on the properties of multi-flyers were conducted and the energy transmission rules of laser after being focused by the lens were analyzed, through which the influences of the parameters for each layer of multi-flyers on the average velocity and impact pressure were achieved. Taking advantage of PDV high-speed testing system, the accelerating processes of flyers with different parameters were analyzed, which solved the problem of testing the performance of small-size flyers. (3) The energy efficiency of laser-driven miniflyer priming system is influenced by laser energy、transmission path and flyer parameters at the same time.The results of energy analytic method and experimental research shows that multi-flyers with absorption layer and insulator layer added could effectively reduce material surface reflections and radiation losses, as well as the laser energy consumed by the gasification of materials and the diffusion of plasma, so as to achieve the purpose of enhancing the velocity of flyers.In237.0mJ laser energy, the0.05/0.7/0.7/20.0μm thickness、1.0mm diameter multi-flyer could reach a maximum velocity of2301m·s-1, and the energy efficiency of this was40.68%. In addition, impact pressure of the multi-flyer increased dramatically with comparison of the single one.The maximum velocity of designed multi-flyer could meet the critical value which had been calculated.