Study On Dust Cloud Pyrotechnic-pumped Laser Technology For Efficient Luminescence Without Electricity

The pyrotechnic-pumped laser is a unique solid-state laser characterized by its self-sustaining energy,flexibility,strong environmental adaptability,and substantial pump energy.Due to its inherent advantages,it holds potential for extensive applications in specialized environments such as military,space,and outdoor settings,particularly for laser-induced damage,protection,and self-rescue devices.Given that each kilogram of pyrotechnic contains4-5 MJ of chemical energy,only 10%of this energy needs to be converted into laser pump energy to achieve hundreds of thousands of joules of pulsed laser weapon energy output.Therefore,the study of pump light conversion efficiency becomes a research focus for pyrotechnic-pumped lasers.Additionally,addressing the shockwave effects during combustion is also a significant aspect of this laser technology application research.Building on the foundation of our group’s previous studies,this thesis pioneers the research on dust cloud pyrotechnic-pumped Nd:YAG pulsed lasers,achieving a pulse width of 50 ms and an energy output of 14.33 J/g.These results will provide a practical design basis for the development of pyrotechnic laser weapons.The main research contents and innovative achievements of the thesis are as follows:（1）Based on the thermal radiation model of pyrotechnic combustion and Lambert-Beer’s law,the use of high luminous efficiency dust cloud pyrotechnics can effectively enhance the conversion efficiency of pump light energy.For this purpose,we designed and built a dust cloud pyrotechnic-pumped laser experimental setup,systematically studying the combustion and pump characteristics of dust cloud pyrotechnics,as well as the spatial layout,formulation,and laser medium of the laser.Using 150 mg of KCl O₄/Zr/Al dust cloud pyrotechnic to pump the Nd:YAG laser medium,we achieved a maximum output of 2.15 J laser energy,with an energy output per unit mass of 14.33 J/g,surpassing the previously reported maximum value of 7.03 J/g.Based on these research results,it can be inferred that using 15 g of pyrotechnic can achieve the laser energy power density required for anti-drone laser weapon damage.（2）Considering the characteristics of dust cloud pyrotechnics,we employed gas-solid two-phase flow theory and methods to simulate key factors affecting laser performance.The simulation results show that the concentration distribution of dust cloud pyrotechnics in the combustion chamber decreases with its movement.Increasing the nozzle airflow speed can enlarge the axial distribution of dust cloud pyrotechnics,which is conducive to improving the matching degree with the laser medium and the optical coupling efficiency.An increase in pyrotechnic quantity will expand the distribution range and concentration,increasing the total pump energy while also reducing the optical radiation efficiency.The nozzle cone angle and turbulence are very beneficial for enhancing the dispersion of dust cloud pyrotechnics,reducing the pyrotechnic concentration by 95.1%and 76%,respectively.Moreover,the simulation study made us realize that the particle size ratio significantly affects the mixing uniformity of the combustible and oxidizer,with the highest synchronization and uniformity at a Zr/KP particle size ratio of 0.388.（3）Based on the adiabatic compression process principle and using entirely electric-free compressed air,we achieved the body ignition combustion of dust cloud pyrotechnics and laser output.The thesis designed and built a compressed air ignition pyrotechnic-pumped laser,studying its ignition and laser output characteristics.Compressed air ignition improves the synchronicity of pyrotechnic combustion.When the compression ratio is 5,pyrotechnics can be ignited,and the combustion time of dust cloud pyrotechnics under normal conditions is shortened by 66%.The high-pressure environment of compressed air reduces the ignition point of pyrotechnics by more than 50%compared to atmospheric pressure.The turbulence formed during the compression process makes the pyrotechnics appear in a dust cloud state.When the pyrotechnic quantity is 10 mg,laser output can be achieved,which is the lowest reported threshold pyrotechnic quantity for light output.The compressed air ignition pyrotechnic-pumped laser completely breaks free from the shackles of electric energy,truly achieving"electric-free"ignition laser energy output.（4）Based on the principle and method of slow combustion of pyrotechnics,by using additives to reduce the combustion rate of pyrotechnics to increase the pyrotechnic quantity and pump time,and using the combustion gas jet to form a dust cloud"product luminescent body",we designed and built a continuous pyrotechnic-pumped laser,studying its combustion process and laser output characteristics.Using 5%phenolic resin-added Zr/KP=57/43pyrotechnic to pump the Nd:YAG laser medium,we achieved the longest continuous pump time of 2430 ms,the maximum laser output energy of 552 m J,and the maximum average power of 0.47 W.Compared with the side continuous pump methods of jet pump and linear pump,the efficiency of jet pump is significantly higher than that of linear pump.In conclusion,through compressed air research,this thesis achieves dust cloud pyrotechnic body ignition high-efficiency luminescent pump Nd:YAG pulsed laser energy output.How to transform this technology into a flexible and lightweight laser weapon requires further work in the design of the pump structure and the laser output resonator.The experimental results of the pulse laser energy output per unit mass in this thesis have solved a key core technology for the development of kilogram-level anti-missile laser weapons.