Abstracts Brochure - CERN

THPCH021
THPCH022
THPCH023
29-Jun-06 16:00 - 18:00 THPCH — Poster Session
Acceleration of Charged Particles by Field of Intensive Electromagnetic Waves and in a
Permanent Magnetic Field
The results of investigations of dynamics of
V.A. Buts, V.V. Kuzmin (NSC/KIPT)
charged particles in field of an intensive electromagnetic
wave and in a permanent magnetic
field are presented. Here we call "intensive" the waves with amplitudes large enough to provide overlapping of
nonlinear cyclotron resonances. There are two mechanisms of unrestricted acceleration in such fields: self-resonance
and stochastic acceleration. Here we focus upon the second type of the acceleration. We found analytical conditions
for stochastic acceleration by different types of waves. It is shown that a state of super-diffusion in energy space
occurs when the amplitude of the accelerating wave is sufficiently high. Kinetic equations, which describe evolution
of particles in these circumstances, are either integro-differential equations or differential equations with fractional
derivatives. The physical nature of such super-diffusion is discussed and nonlinear dynamics of leading centers of
charged particles is studied. We show that there are conditions when the leading centers of particles with different
masses move in opposite directions. This feature can be extremely useful for an isotope separation.
Self-consistent 3-D Electron-cloud Simulations of LHC Beam
J.-L. Vay, M.A. Furman (LBNL) R.H. Cohen, A. Friedman, D.P.
Grote (LLNL)
392
We present initial results for the self-consistent
beam-cloud dynamics simulations for a
sample LHC beam, using a newly developed
set of modeling capability based on a merge
of the three-dimensional parallel Particle-In-Cell accelerator code WARP and the electron cloud code POSINST. Although
the storage ring model we use as a test bed to contain the beam is much simpler and shorter than the LHC, its
lattice elements are realistically modeled, as is the beam and the electron cloud dynamics. The simulated mechanisms
for generation and absorption of the electrons at the walls are based on previously validated models available in
POSINST. We will present the details of the models and our most recent results.
Vlasov Equilibrium of a Periodically Twisted Ellipse-shaped Charged-particle Beam in a
Non-axisymmetric Periodic Magnetic Focusing Field
A new Vlasov equilibrium is obtained for a
J.Z. Zhou, C. Chen (MIT/PSFC)
periodically twisted ellipse-shaped chargedparticle
beam in a non-axisymmetric periodic
permanent magnetic focusing field. The equilibrium distribution function is derived, and the statistical properties
of the beam equilibrium are studied. The generalized envelope equations derived from the kinetic theory recovers the
generalized envelope equations obtained in the cold-fluid theory when the temperature is taken to be zero*. Examples
of periodically twisted elliptic beam equilibrium are presented and applications are explored.
*J. Zhou et al. “Exact Paraxial Cold-Fluid Equilibrium of a High-Intensity Periodically Twisted Ellipse-Shaped
Charged-Particle Beam,” Phys. Rev. ST Accel. Beams, submitted for publication (2005).