Abstract: A 2(1/2) dimensional particle simulation code PLASIM (Plasma and Simulator) is developed with the purpose of studying the interaction of laser and plasma.The algorithm of the code is introduced.A main characteristics of the code is that it can simulate collision effects by adopting β-particle cloud.Another characteristics is that electrons and ions are both relativistic. So the computation results are more believable when incident laser is ultra-intense.

Key words: particle simulation, laser-plasma interaction, Coulomb collision, plasma bubble