then first of all thanks for simulation
simulation now works correctly but there would be so many parameters you can tweak.
1. time step is expected to reach 0.500 us, from 0.01us, because the simulation is too slow at high value of scale eg 600
2. the length of the black mark that represents the trajectory should be more long, it tends to disappear with the advance of the particle. at 600 scale
3. the scale of 600, sigma must reach a maximum of 3000 and not 9000, as it is now, because the fixing of parameters is too difficult
4. the dimension of velocity vector shoud be became largest if the scale increase. but not big only a bit