说明：  Particle in cell 方法的matlab代码，非常基础，算例是空间存在一带电平板情况下，等离子体的电场分布和离子密度分布。作为入门非常好。
(Particle in cell method matlab code, very basic, there is a numerical example is charged under the flat space case, the electric field distribution of plasma and ion density distribution. As entry is very good.)