超高速碰撞产生的电磁辐射

The electromagnetic radiation from hypervelocity impact is an important physical phenomenon of solid matter under strong impact loadings, and the research results have important application value in fields of deep space exploration, protection design of spacecraft against space debris, assessment of weapon damage, etc. In this paper, the electromagnetic radiation caused by hypervelocity impact was briefly summarized. The time-frequency characteristics of microwave and flash by hypervelocity impact under various collision conditions were respectively provided. The radiation models of microwave generated by hypervelocity impact were analyzed from two aspects of material fragmentation and plasma phase transition. The luminescence mechanisms during hypervelocity impact were described as a whole, and the radiation models of continuous spectrum and line spectrum were performed. The shortcomings and development trend of electromagnetic radiation by hypervelocity impact were pointed out. The results show that the intensity and frequency of microwave and flash are closely dependent on the target thickness, impact material, environmental pressure as well as collisional velocity and angle. The microwave is in the form of pulses lasting from a few to hundreds of microseconds. The intensity of the flash, however, accumulates rapidly and then decays slowly. When the plasma is not accomplished during the hypervelocity impact, the microwave radiation is mainly formed because of the movement of ionized debris. Once the plasma is formed, the effects of the collision radiation in the plasma, namely the bremsstrahlung and recombination radiation, and the expansion of the plasma should also be taken into account, and the specific spectrum lies on the characteristic parameters of plasma. In vacuum, only the gasification and plasma due to the impact are necessary to be considered in the flash spectrum, while the gasification and even plasma phase transition resulted from the ablation between the gas and debris should be involved at high environmental pressure.