N-body Monte Carlo simulation on high contrast biology transmission electron microscope

Inner and outer diameters of the phase plate limit the number of electrons passing and can affect the high-resolution information in the phase contrast image. A more practical column model including the First Condenser Lens CL1, Second Condenser Lens CL2, Mini-condenser Lens CM and Objective Lens(OL) was first built to obtain the beam performance at the upper surface of the phase plate. N-body Monte Carlo simulation was used to avoid error caused by big defocus from the Guassian image plane where a lens field exists. In building the motion equation in a practical field, second order finite element method and Hermite function interpolation were applied to get the axial field and its arbitrary order derivative. N motion equations were then solved by fifth-order Runge-Kutta algorithm and the performance of un-scattered and scattered electrons was given for a 200kV TEM. Results show that the beam spots are 2.7m and 39m for un-scattered and scattered electrons respectively. N-body Monte Carlo simulation can obtain both positions and velocities of un-scattered and scattered electrons at the arbitrary plane with aberrations being considered, which effectively avoids error from the defocus distance in classic aberration integrated methods.