Optimization of Monte Carlo codes using null collision techniques for experimental simulation at low E/N

The use of the null collision method in Monte Carlo simulations of electron and ion motion in gases is briefly reviewed, with particular reference to conditions where only a handful of collision cross sections are required to describe the electron/ion-molecule interaction. An efficient algorithm is proposed for use in such conditions as an alternative to S.L. Lin and J.N. Bardsley´s (1977) implementation of H.R. Skullerud´s (1973) original null collision algorithm. The alternative implementation is described, and some examples of the advantages of the new algorithm are given for electron scattering from argon, helium, and the Reid ramp model gas