The implementation of a 2D parallel particle-in-cell (PIC) simulation with domain partition is presented.Its performance is tested on a PC cluster of 16 Pentium Ⅲ 1.6 CPUs. It shows that the parallel efficiency decreases with the increasing of computation nodes while keeping the calculation size; and the parallel efficiency increases with the size of physical problem while keeping the number of computational nodes. It means that parallel computing is suitable for large physical problems. As an example, a calculation on plasma beam instability is performed with this parallel PIC code. The results show that in the linear growth stage, the excited Alfven waves propagate in the direction of ambient magnetic field, and they satisfy a resonant condition ω-kV_b=-Ω_i, where ω and k are frequency and wave number of the excited Alfven waves, respectively, V_b the beam velocity and Ω_i the ion cyclotron frequency.

In the PIC method of particle simulations,the physical variables related to the fields are assigned to the grids,while the particles can be anywhere in the simulation domain.Using this method,we design a 2D particle simulation code,and numerically study two common physical phenomena in space physics:beam instability and magnetic reconnection.In the beam instability,the beam plasma streams in the background plasma with the velocity V_b=10V_-A(V_-A is Alfvén speed),and the Alfvén waves are excited through wave-particle interactions.In the magnetic reconnection,the Harris current sheet can induce the magnetic reconnection,and the B_-y shows quadrupolar structure.

Hybrid codes treat ions as particles and electrons as fluid to study physical problems in plasma. A 2D hybrid code is designed, and in order to test it, the beam instabilities in plasma using this code is studied. The results coincide with the theoretical analysis and 1D hybrid simulations.