1 redesign the layout to fit my usual format
2 added text on green electrons for eye-balling purposes
3 set initial r = 0.1 instead of the usual 0.03, the electrons are moving too fast for r=0.03
4 add magnetZs as slider for the initial magnetZ, modified the codes slightly magnetZ = freeFallZ = magnetZs/4 ; // insead of the older code = maximum/4
5 bug the text didn't compile in Java3D so i did it on simple3D

to do list
to add the model for a cylinder ?, currently it is only for a ring of very small Z thickness