反常衍射近似在测量圆柱形粒子粒径分布中的应用

在光全散射法颗粒粒径测量中,基于米氏(Mie)理论的计算方法只能求出均匀球形粒子的消光系数,而且计算复杂。通过反常衍射近似(ADA)代替米消光系数,可以简化粒径分布的反演过程。对使用反常衍射近似方法计算圆柱形粒子消光系数的可行性以及限制条件进行深入的研究,并在非独立模式算法下,采用遗传算法反演粒径分布。仿真结果表明,当粒子的相对折射率在一定范围内时,利用反常衍射近似反演圆柱形粒子的粒径分布是完全可行的,反演结果稳定、可靠。对消光值测量结果加入3％相对误差时,反演误差为5．7％。该方法具有简单、直观、计算速度快等优点,适合颗粒粒径的在线测量。

Application on Circular Cylinder Particle Size Distribution Based on Anomalous Diffraction Approximation

In total light scattering particle sizing technique,the calculation of extinction efficiency based on Mie theory can only be applied to the homogeneous spherical particles,what is important is that the Mie theory is expensive in both time and resources.Using the anomalous diffraction approximation(ADA)instead of Mie extinction efficiency can simplify the inversion of particle size distribution.The feasibility and limitations of using the anomalous diffraction approximation for calculating the extinction efficiency of circular cylinder particles are investigated.The genetic algorithm is used to inverse the particle size distribution under the dependent model algorithm.Simulation experiments illustrate that it is feasible to use the anomalous diffraction approximation to inverse the circular cylinder particle size distribution in the total light scattering technique,and the inversion results are steady and reliable.The inversion error is 5.7% when 3% relative error is put in the extinction measurement values.The method has advantages of simplicity,rapidity,and suitability for in-line particle size measurement.