Study On The Effect Of Interface In The Process Of Laser Ignition

The interaction characteristics of laser and B/KNO₃ in open system and the influence of interface (glass window, Cu-coated glass window and Al-coated glass window) in the process of laser ignition were investigated in this thesis. The research work involved the interaction process of laser-medium and laser-medium-B/KNO₃. The main works and achievements are presented as follows.(1) The ignition characteristics of B/KNO₃ and B/KNO₃/Phenolic resin with different mass ratio in open system were studied respectively. B/KNO₃ with mass ratio of 50/50 possessed the lowest energy threshold which was 7.6mJ. B/KNO₃/phenolic resin with mass ratio of 40/60/5 possessed the lowest energy threshold which was 4.05mJ. It was found that blending phenolic resin into B/KNO₃ improved the laser sensitivity of the powders. The ignition delay time decreased with increasing the energy density.(2) The laser permeation ratios of different interfaces were measured. The interaction processes of laser and different coated windows were recorded by high-speed photography. Mach—Zehnder interferometer was used to obtain the interferometry fringes of the film surface. The temperature distribution was calculated by analyzing the interferometry fringes.(3) The ignition characteristics of laser-medium-B/KNO₃ were studied. It was shown that adding interface decreased the laser sensitivity and shortened the ignition delay time. The ignition characteristics of laser-glass window-B/KNO₃ were the best in confined system.(4) The laser ignition processes were recorded by high-speed photography. The 'second combustion' phenomenon was captured in open system, and the 'third combustion' phenomenon was first discovered in confined system.(5) One-dimensional finite difference model which involved glass window field was developed. The results of the computations were in basically agreement with the test measurements.