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Updated: May 20, 2026

A 100 KW Class Applied-field Magnetoplasmadynamic Thruster
Published on: December 22, 2018
Magnetic bucket for rotating unmagnetized plasma
Noam Katz1, Cami Collins, John Wallace
1Department of Physics, University of Wisconsin, Madison, Wisconsin 53706, USA. nkatz2@wisc.edu
Abstract:
A new experiment is described which generates flow in unmagnetized plasma. Confinement is provided by a cage of permanent magnets, arranged to form an axisymmetric, high-order, multipolar magnetic field. This field configuration-sometimes called a "magnetic bucket"-has a vanishingly small field in the core of the experiment. Toroidal rotation is driven by J × B forces applied in the magnetized edge. The cross-field current that is required for this forcing flows from anodes to thermionic cathodes, which are inserted between the magnet rings. The rotation at the edge reaches 3 km/s and is viscously coupled to the unmagnetized core plasma. We describe the conditions necessary for rotation, as well as a 0-dimensional power balance used to understand plasma confinement in the experiment.
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