K9窗口Ti/Al薄膜对B/KNO₃/PF激光点火特性的影响OA

To reveal the influence laws and action mechanisms of film thickness and working conditions with/without an acceler-ation chamber on the laser ignition performance of thin films,photoelectric detectors,high-speed cameras,spectrometers and schlieren system were adopted to investigate the laser ignition sensitivity,ignition delay time,plasma characteristics of laser-ablated thin films,laser-induced plasma shock waves and particle motion characteristics of thin films for B/KNO3/PF ener-getic powder under various film thicknesses and acceleration chamber thicknesses.The results show that the 204 nm-thick Ti/Al-1 thin film facilitates the laser ignition process,lowering the laser ignition energy fluence threshold from 3.94 J·cm-2(without a thin film medium)to 3.67 J·cm-2.By contrast,the 488 nm-thick Ti/Al-2 and 874 nm-thick Ti/Al-3 thin films raise the ignition en-ergy fluence threshold,with corresponding threshold values of 4.23 J·cm-2 and 4.85 J·cm-2,respectively.The laser ignition de-lay time increases in the order of Ti/Al-1,without thin film medium,Ti/Al-2 and Ti/Al-3,following the same trend as the laser ig-nition energy fluence threshold.As the film thickness rises,both the electron temperature and electron density of laser-ablated film plasma decrease.When an acceleration chamber with a thickness of 0.1 mm and inner diameter of 0.6 mm is placed be-tween the thin film and energetic powder,no obvious variation occurs in the laser ignition sensitivity of the powder.The mini-mum ignition delay times of the three film systems are shortened by 0.21 ms,1.64 ms and 2.67 ms compared with the condition without an acceleration chamber,and the optimized delay times are 1.6 ms,1.0 ms and 1.3 ms in sequence.There exists an opti-mal matching relationship between thin film medium thickness and acceleration chamber thickness.The Ti/Al-2 and Ti/Al-3 thin films achieve the optimal ignition performance when matched with 0.1 mm-thick and 0.2 mm-thick acceleration chambers,respectively.