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DOE OSTI · 2567654

Rotational pumping revisited

O'Neil, Thomas M. (ORCID:0000000299041368)
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Abstract

This paper considers a pure electron plasma, with a small admixture of negative ions, confined in a Penning–Malmberg trap. When a diocotron mode is excited on the plasma, the end sheaths of the plasma are azimuthally distorted. During reflection at a distorted end sheath, an ion steps off of the surface characterizing the drift motion in the plasma interior, and this step produces transport. The diocotron mode transfers canonical angular momentum to the ions, and in response damps. These transport mechanism and associated damping are called rotational pumping. It is particularly strong when the axial bounce motion and the rotational drift motion, in the rotating frame of the mode, satisfy a resonance condition. This paper calculates the transport flux of ions and the associated damping rate of the mode in the resonant regime. Previous papers have discussed the theory and the experimental observation of rotational pumping for the special case of a diocotron mode with azimuthal wave number l = 1, and this paper extends the theory to modes with l≠1, which may sound like a trivial extension, but in fact is not.

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71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICSHamiltonian mechanicscoordinate systemelectrostaticsplasma instabilitiesplasma properties and parameters

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O'Neil, Thomas M. (ORCID:0000000299041368). 2021-10-08. Rotational pumping revisited. https://doi.org/10.1063/5.0064401

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