[Triumf-seminars] TRIUMF Accelerator Seminar today at 10:00

[TRIUMF Seminars]

Date/Time: Fri 2012-09-07 at 10:00

Location:  ISAC II Conf. Rm.   

Speaker:   Antoine Julien Cerfon (MIT, USA)

Title:     Analytic fluid theory of beam spiraling in high-intensity cyclotrons

Abstract: Using a two-dimensional fluid description, we investigate the nonlinear radial
longitudinal dynamics of intense beams in storage rings and cyclotrons. 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 ExB
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 PIC simulations.

Stimulants available 15 minutes before the talk.

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