There was a time when physicists where concerned about electron internal structure. The rotating ring model was one of the proposals to explain how a charge density could become stable against electrostatic repulsion, by postulating that the charge is distributed as a ring with angular velocity, which engenders a magnetostatic force that exactly cancels the electrostatic repulsion (actually they don't exactly cancel, they both become equal to the centripetal force)
Now we don't concern ourselves with the electron internal structure anymore, but i wonder if there are other physical circumstances where we can still see a ring of charges to become stable against self-repulsion by this mechanism
One of the problems i see is that it is usually assumed in the analysis that the ring rotates at the speed of light. My question is:
Is possible to stabilize such structure by physical sub-light tangential velocities of the ring?
Edit There have been some research on a related area of nuclear phenomena, namely high spin nuclear deformation (a book reference about such excitations here), a very interesting application of the above ideas is to look out to reduce or eliminate nuclear decay processes in unstable nuclei, by applying a high spin with a strong background magnetic field to such nuclei, something i highlighted in the comments to this answer.