烟颗粒对太赫兹波衰减特性的影响研究

太赫兹成像系统相对于普通红外线成像系统而言,其受温度和烟雾密度的影响较小,将其引入火场环境侦测中能较好地解决火场环境能见度低的问题。但太赫兹波在火场烟气环境中传播时,会受到烟颗粒的吸收和散射作用影响,造成其传播特性发生变化,因此有必要开展烟颗粒对太赫兹波衰减特性的影响研究。采用离散偶极子近似法进行模拟运算,结合烟颗粒分形凝聚体结构,研究了太赫兹波长为31.25~55.55μm、烟颗粒有效半径为0.05~3μm时,单个烟颗粒对太赫兹波的散射、吸收作用;对比分析了不同有效半径时烟颗粒散射场的分布。结果表明:烟颗粒的消光截面随入射波长的增加而减小,随烟颗粒有效半径的增加而增大;随着烟颗粒有效半径的增加,其前向散射逐渐增大,烟颗粒的分形凝聚体结构会使散射场呈不对称分布。

Influence of Smoke Particles on the Attenuation Characteristics of Terahertz Waves

Compared with ordinary infrared imaging system,terahertz fire imaging system is less affected by temperature and smoke density,so it can solve the problem of low visibility in fire scene environment detection.When a terahertz wave propagates in the fire scenario,it will be absorbed and scattered by smoke particles,which will change its propagation characteristics.Therefore,it is necessary to study the influence of smoke particles on the attenuation characteristics of terahertz wave.This paper applies the discrete dipole approximation method to the simulation operation.Combining the smoke particle's fractal agglomerate structure,the paper studies the scattering and absorption of terahertz waves by individual smoke particle with the terahertz wavelength being 31.25~55.55μm and the effective radius of the smoke particles being 0.05~3μm.The paper also analyzes the distribution of the scattering field of smoke particles at different effective radius.The results show that the extinction cross section decreases with increasing wavelength and increases with the effective radius of the smoke particles.As the effective radius of the smoke particles increases,the forward scatter gradually increases,and the fractal condensate structure of the smoke particles causes the scattering field to be asymmetrically distributed.