Analytic fluid theory of beam spiraling in high-intensity cyclotrons
Name
Cerfon-2013-Analytic fluid theory of beam spiraling in high-intensity cyclotrons.pdf
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1.09 MB
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Author(s)
Cerfon, Antoine J.
Freidberg, Jeffrey P.
Parra Fabian, Ignacio Esteban
Antaya, T. A.
Date Issued
February 2013
Journal
Physical Review Special Topics - Accelerators and Beams
Publisher
American Physical Society
Citation
Cerfon, A. J. et al. “Analytic Fluid Theory of Beam Spiraling in High-intensity Cyclotrons.” Physical Review Special Topics - Accelerators and Beams 16.2 (2013).
Version
Final published version
Abstract
Using a two-dimensional fluid description, we investigate the nonlinear radial-longitudinal dynamics of intense beams in isochronous cyclotrons in the nonrelativistic limit. With a multiscale analysis separating the time scale associated with the betatron motion and the slower time scale associated with space-charge effects, we show that the longitudinal-radial vortex motion can be understood in the frame moving with the charged beam as the nonlinear advection of the beam by the E×B velocity field, where E is the electric field due to the space charge and B is the external magnetic field. This interpretation provides simple explanations for the stability of round beams and for the development of spiral halos in elongated beams. By numerically solving the nonlinear advection equation for the beam density, we find that it is also in quantitative agreement with results obtained in particle-in-cell simulations.
MIT Department
Massachusetts Institute of Technology. Department of Nuclear Science and Engineering
Massachusetts Institute of Technology. Plasma Science and Fusion Center
Terms of Use
Creative Commons Attribution 3.0
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.1103/PhysRevSTAB.16.024202
