Draw a torus and then draw rectangular "bands" across it, they will represent the containment magnets.
Due to pure geometry, the area closer to the center will have a smaller distance between bars. This means that the magnetic field will be stronger near the center.
This in turn means that particles will separate (depending on charge) and drift to the sides. It seriously interferes with the containment.
You can fix that by changing the torus into something resembling "8", so that particles move to one side when they fly through the upper part, but then they'll move back as they fly through the lower part.
Of course, you can't just do that in 2D because the part in the middle of "8" will have no magnetic field. You need something without self-intersections. You can try to move one side up and another down. But that doesn't quite work either because you will get another set of preferred directions.
So instead you go with the gentle twisting, resulting in the Möbius-looking shape.
Draw a torus and then draw rectangular "bands" across it, they will represent the containment magnets.
Due to pure geometry, the area closer to the center will have a smaller distance between bars. This means that the magnetic field will be stronger near the center.
This in turn means that particles will separate (depending on charge) and drift to the sides. It seriously interferes with the containment.
You can fix that by changing the torus into something resembling "8", so that particles move to one side when they fly through the upper part, but then they'll move back as they fly through the lower part.
Of course, you can't just do that in 2D because the part in the middle of "8" will have no magnetic field. You need something without self-intersections. You can try to move one side up and another down. But that doesn't quite work either because you will get another set of preferred directions.
So instead you go with the gentle twisting, resulting in the Möbius-looking shape.