COLLECTIVE BEHAVIOR OF NONNEUTRAL PLASMA IN A KINGDON TRAP

Pancake-like clouds of non-neutral plasma confined in near-circular orbits in a cylindrical electrostatic (Kingdon) trap will have similarities to planetary rings, galaxies, and accretion disks. For example, the rotation is sheared, interparticle collisions cause radial spreading, and there are spiral density waves and bending waves similar to those observed in the rings of Saturn. The dispersion relations have one term with a change of sign as a consequence of the difference in sign between the Coulomb force and the gravitational force. Disks may be subject to negative mass instabilities if there is insufficient spread in the particle velocities. Charged dust particles have a sufficiently long confinement time to allow experimental observations of these waves and instabilities. © 1995 American Institute of Physics.