Hello all, I'd truly appreciate if you could provide me with guidance on this. I'm trying to find the electric field inside an octopole trap analytically to compare results against my numerical calculations. I'm pretty sure it is analytically obtainable, but do not know how to proceed. Any help please? Attached is a photo that shows the structure of the electrodes generating the electric field (yellow parts): four electrodes on the bottom, and four on top exactly like those underneath but with opposite polarity. The structure is capable of trapping dielectric particle right in the middle.