Numerical simulation of internal charging inside teflon film

The charge accumulation process inside a Teflon® film under electron irradiation is numerical simulated by tracking injected electrons based on Monte-Carlo methodology. Each electron inside the material is tracked three-dimensionally using the non-relativistic equations of motion. Collision processes between an electron and an atom consisting of Teflon (CF4) are selected by Monte-Carlo strategy and the electron status after collision is determined. Elastic and inelastic collision processes are both considered. The inelastic collision processes included are ionization, phonon interaction and trapping effect. A PC based parallel computer is introduced to accelerate the computation so that the realistic time scale is attained. Computed charge density distributions are compared with other simulation results and the results show good agreement. There was no comparison of charge density distribution with that of experiment in the past due to difficulty of obtaining them. The experimental results obtained by our innovative measurement system show more complicated features mainly causing from radiation induced conductivity. The comparison between these results indicates that inclusion of radiation induced conductivity (RIC) is necessary for numerical simulation.