Theoretical Study On Extinction Characters Of Non-Spherical Particles And Their Smokescreen

Smokescreen as an effective defense against precision-guided weapon becomes more and more important in high-tech warfare. This paper deals with theoretical study on extinction characters of non-spherical particles and their smokescreen, which is one of the fundamental researches of smokescreen technology. The mathematical radiation extinction model of particles is discussed, and numerical simulation of extinction characters of particle and smokescreen is developed.Firstly, the current status of particle extinction study is reviewed, and the methods for computing the particle extinction characters are compared. Secondly, the mathematical radiation extinction model of nonspherical particle is developed based on T-matrix method, and a computer program is designed to calculate the extinction cross section, scattering cross section, absorption cross section and scattering phase function of fixed or randomly oriented axially symmetric particle. Thirdly, the cluster-cluster aggregation model is used to study the possible structure of aggregated smokescreen particle. We also develop the mathematical radiation extinction model of aggregated particle based on T-matrix method. Associated with Monte Carlo method, another computer program is designed to simulate the extinction cross section and scattering cross section of actually aggregated particle. Compared with other methods and known results, these programs are proved accurate and effective. Further more, the effect of size, shape, surface character, aggregation and refractive index of the particle on extinction characters are discussed through calculation results, and some of them are experimental studied. At last, the radiation transmit process in smokescreen is discussed, and the transmitted radiation energy distribution is obtained from extinction characters of particles. The relationship between transmittance and smokescreen concentration is experimental studied, the experiment results agrees with calculated results. We also discuss the application limit and error of Lambert-Beer law in smokescreen studies.