361,490 research outputs found
Stochastic collective dynamics of charged--particle beams in the stability regime
We introduce a description of the collective transverse dynamics of charged
(proton) beams in the stability regime by suitable classical stochastic
fluctuations. In this scheme, the collective beam dynamics is described by
time--reversal invariant diffusion processes deduced by stochastic variational
principles (Nelson processes). By general arguments, we show that the diffusion
coefficient, expressed in units of length, is given by ,
where is the number of particles in the beam and the Compton
wavelength of a single constituent. This diffusion coefficient represents an
effective unit of beam emittance. The hydrodynamic equations of the stochastic
dynamics can be easily recast in the form of a Schr\"odinger equation, with the
unit of emittance replacing the Planck action constant. This fact provides a
natural connection to the so--called ``quantum--like approaches'' to beam
dynamics. The transition probabilities associated to Nelson processes can be
exploited to model evolutions suitable to control the transverse beam dynamics.
In particular we show how to control, in the quadrupole approximation to the
beam--field interaction, both the focusing and the transverse oscillations of
the beam, either together or independently.Comment: 15 pages, 9 figure
Beam Dynamics and Beam Losses - Circular Machines
A basic introduction to transverse and longitudinal beam dynamics as well as
the most relevant beam loss mechanisms in circular machines will be presented
in this lecture. This lecture is intended for physicists and engineers with
little or no knowledge of this subject.Comment: 18 pages, contribution to the 2014 Joint International Accelerator
School: Beam Loss and Accelerator Protection, Newport Beach, CA, USA , 5-14
Nov 201
Longitudinal Momentum Mining of Beam Particles in a Storage Ring
I describe a new scheme for selectively isolating high density low
longitudinal emittance beam particles in a storage ring from the rest of the
beam without emittance dilution. I discuss the general principle of the method,
called longitudinal momentum mining, beam dynamics simulations and results of
beam experiments. Multi-particle beam dynamics simulations applied to the
Fermilab 8 GeV Recycler (a storage ring) convincingly validate the concepts and
feasibility of the method, which I have demonstrated with beam experiments in
the Recycler. The method presented here is the first of its kind.Comment: 11 pages, 3 figure
Beam halo dynamics and control with hollow electron beams
Experimental measurements of beam halo diffusion dynamics with collimator
scans are reviewed. The concept of halo control with a hollow electron beam
collimator, its demonstration at the Tevatron, and its possible applications at
the LHC are discussed.Comment: 5 pages, 4 figures, in Proceedings of the 52nd ICFA Advanced Beam
Dynamics Workshop on High-Intensity and High-Brightness Hadron Beams
(HB2012), Beijing, China, 17-21 September 201
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