Electric field betwen laterally displaced parallel plates

irstudent

I am struggling with a problem which involves the calculation of the nonuniform electric field fields between two identical parallel plates in which one of the plates is slightly displaced in lateral direction with respect to the other plate (i.e. they do not overlap perfectly). The gap between the overlapping parts of the plates is much smaller than the plate dimensions.

In particular, I am interested in calculating the lateral electric force acting on the displaced plate. I presume that this force is mainly generated from the change in the fringe fields between the edges of the plates.

I have searched the literature for papers which cover this special case of a parallel plate capacitor, however, I have found nothing so far. Why is that so? Is it because the asymmetry of the plate arrangement renders an analytical solution impossible or very cumbersome? Can anyone help me by directing me to published work or by providing me with the general (analytical) approach in attacking this problem?

Thanks a bunch!!

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mfb

Mentor
I would be surprised if there is an exact analytic solution. You have to take into account that the plates have a finite width, edges and so on. I think numerical simulations can give you some formula to approximate the forces.

irstudent

I was wondering if the problem becomes analytically solvable if it becomes two-dimensional by assuming that both plates extend into infinity in the direction perpendicular to the drawing plane.

mfb

Mentor
I already used this assumption to look at the system ;). It should be fine with most interesting setups.

irstudent

I already used this assumption to look at the system ;). It should be fine with most interesting setups.

thanks for your thoughts. Even in the two-dimensional case, the fact that the problem space cannot be confined to a region of which the boundary conditions are given either by specification or by symmetry considerations, makes this problem analytically impossible to solve. I guess, that's why the use of conformal mapping may stand no chance in solving this problem, because it requires symmetry in the plate configuration.

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