Hello, I am modelling a system of three electrostatic electrodes to focus an Ar+ Ion beam. By using the "Einzel Lens" tutorial, I get good results if I choose electrons or positrons as Particles. But as soon as I choose a "user defined" particle with a charge number of +1 and the mass of an Argon Atom (39,938 [amu]) the beam is not extending. It is only about a few mm long. The same happens when I choose an inlet instead of a particle beam. It seems like the beam spreading depends on the particle mass. Does anyone know what could be the problem?
Thank you