Winding an electromagnet ring coil to get radial magnetic field
You can wrap several bar magnets. (At least 2, but the more the better.) Pay attention to wind them equally.

Align the bar magnets in parallel, so all north poles point inward. Like this


Fix them in place. If you don't, they will mutually push eachother apart when you energize them.

It is suggested to power them serially. That way each carries exactly the same current. If you wire them serially sequentially, though, you will also have a small axial magnetic field as the current traverses the circle once. You can get rid of that by wiring their series configuration in a way that moves e.g. from left to right.


Here is a Falstad link with 4 magnets facing in on each other. As expected the central field is zero. and the field lines exit both sides in axial direction creating large axial fields beyond the plane of the circle. The axial direction can be stuffed with more magnets facing in on the center. Falstad calls this configuration fittingly &quot;monopole attempt&quot;. As magnetic monopoles cannot be created in this way. The field will always exit through the gaps.