Abstract: Monte Carlo method is used to study light extinction of smoke screen with clustered agglomerates consisting of spherical primary particles in a cluster-cluster aggregation(CCA) model.Extinction factor and absorption factor of randomly oriented smoke screen with clustered agglomerates are calculated with discrete dipole approximation(DDA).It shows that exinction properties are determined by radius and number of primitive particles besides refractive index and extinction properties can be decreased by aggregation.At a given primitive particle number,maximum extinction is obtained with optimum radius of primitive particles.

Key words: smoke screen, cluster particle, extinction properties, discrete dipole approximation method