Weighted sample particles in the theory of Coulomb collisions in plasmas

Nanbu (Phys. Rev. E, 55-4 (1997), 4642-4652) found the law of Coulomb collisions in plasmas: A succession of small-angle binary collisions is grouped into a unique binary collision with a large scattering angle; the law of scattering is given by the exponential cosine function. Here is proposed a Coulomb collision algorithm for weighted sample particles based on the above paper. We considered two cases; one is the case when the weight of sample particles is different from species to species, and the other is the case when the weight of sample particles is different from particle to particle. Sample calculations show that the weight algorithm works well. (author)