PPPL-4616
New Spectral Method for Halo Particle Definition in Intense Mis-matched Beams
Authors: Mikhail A. Dorf, Ronald C. Davidson, and Edward A. Startsev
Abstract: An advanced spectral analysis of a mis-matched charged particle beam propagating
through a periodic focusing transport lattice is utilized in particle-in-cell (PIC) simulations. It is
found that the betatron frequency distribution function of a mismatched space-charge-dominated
beam has a bump-on-tail structure attributed to the beam halo particles. Based on this
observation, a new spectral method for halo particle definition is proposed that provides the
opportunity to carry out a quantitative analysis of halo particle production by a beam mismatch.
In addition, it is shown that the spectral analysis of the mismatch relaxation process provides
important insights into the emittance growth attributed to the halo formation and the core
relaxation processes. Finally, the spectral method is applied to the problem of space-charge
transport limits.
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Submitted to: Physics of Plasmas (March 2011)
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Download PPPL-4616 (pdf 979 KB 26 pp)
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