ABSTRACT
This chapter extends the sphere code by including material interactions and by letting ions neutralize on surface impact. It incorporate Monte Carlo and Direct Simulation Monte Carlo collisions to model charge exchange, momentum transfer, and ionization. The chapter explains the sampling of the Maxwellian velocity distribution, and extends the output capabilities to include stream velocity, temperature, and particle phase plots. It briefly reviews steps needed to adapt the simulation to an arbitrary geometry described by a surface mesh.
