Discussion Forum

Hi,

I have a radially symmetric magnetic lens. I want to simulate how input particles (with xy distribution and certain velocity) go through the magnetic lens and what is the distribution. I used Magnetic Fields and Charged Particle Tracing studies. Since the magnetic lens is radially symmetric, I can use 2D simulation to calculate the magnetic field. However, Charged Particle Tracing is only available in 3D. So I have to do the whole simulation in 3D. In addition to the increased simulation time, I observed simulation errors when the electron beam focus is less than 5um. I uses a 2D circular beam with initial positions on Projected plane grid. I expect the beam to be still circular and still on grid with rotated coordinates. Instead, I got very irregular shaped spot with electron distributions that look random. I significantly increased mesh sampling and uses fine time steps near the focus, but still couldn’t resolve the problem. I’m wondering if there are any good suggestions to this problem.

I finally tried to use field precision to solve this problem. It’s much faster since it uses 2D magnetic field and it still takes 2D input electron distributions. It also gives more accurate results. I wish COMSOL could have similar feature.

Does anyone have similar problems?

Thanks! Jingyi