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Importance of rings
Spinning the magnet produces E = v x B
Electric forces confine dust to the equatorial plane.
Charging the magnet produces analogous behaviour (Phys.Rev).
Can we combine the two approaches to achieve both dust & plasma confinement?
Notes:
Why a flat ring? Yokota argues that the force on the dust grains is not directly magnetic, but is an induced electric force caused by the rotating magnetic field. This induced electric field, which he draws in the figure to the right as equipotential lines, drives the dust to the equator of the spinning system. Thus, he argues, both his laboratory prototype and Saturns dust rings form these thin structures in response to a spinning magnetic field.
Well, the induced electric field points inward and is very similar to a field generated by applying voltage directly to the magnet. An additional feature, is that a DC voltage applied this way can also create a plasma breakdown and generate the plasma needed for the dusty plasma