Abstracts Brochure - CERN

THPCH — Poster Session 29-Jun-06 16:00 - 18:00
charge density is approximately constant this increase can be reached by the beam cross section growth. It can not be
done for the most known accelerator structures. The appropriate acceleration schema is proposed and the results of
the beam dynamics analysis and simulation are presented and discussed.
Resonance Trapping, Halo Formation and Incoherent Emittance Growth due to Electron
Cloud
The pinched electron cloud introduces a
tune shift along the bunch, which together
with synchrotron motion, leads to a periodic
crossing of resonances. The resonances are
E. Benedetto, E. Benedetto (Politecnico di Torino) G. Franchetti
(GSI) G. Rumolo, F. Zimmermann (CERN)
excited by the longitudinal distribution of the electron cloud around the storage ring. We benchmark the PIC code
HEADTAIL against a simplified weak-strong tracking code based on an analytical field model, obtaining an excellent
agreement. The simplified code is then used for exploring the long term evolution of the beam emittance, and for
studying more realistic lattice models. Results are presented for the CERN SPS and the LHC.
Halo and Tail Generation Studies for Linear Colliders
Halo particles in linear colliders can result
in significant losses and serious background L. Neukermans, H. Burkhardt (CERN)
which may reduce the overall performances.
We present a study of various halo generation processes with numerical estimates. The aim is to allow to predict and
minimize the halo throughout the accelerator chain including the final focus up to the experimental detectors. We
include estimates for the planned CLIC beam line.
Acceleration of Charged Particles by Field of Intensive Electromagnetic Waves in a Vacuum
The dynamics of charged particles in a field
of intensive electromagnetic waves or im- V.A. Buts, V.V. Kuzmin (NSC/KIPT)
pulses is studied. A wave is called “intensive”
when its strength parameter* approaches or become larger than one. We show that conventional schemes of
acceleration such as IFEL** are not efficient. A stochastic instability suppresses its realization and leads to energy
spread of accelerating particles and to destruction of accelerating bunches. From other side, the energy restrictions,
caused by a radiational friction in a system of laser acceleration can be lifted. Moreover, the frictional forces can
enhance acceleration of particles by a laser radiation. Analytical conditions for this enhancement are determined.
Friction becomes particularly significant for interaction of electromagnetic waves with clusters. All particles in a laser
pulse could move identically because of the friction. Additional benefits for acceleration under these conditions are
provided by circularly polarized laser impulse. In this case energy of particles repeats the shape of the impulse’s
envelope and the acceleration is very efficient. Several new IFEL and FEL*** schemes are discussed.
* Epsion==e E/( m cΩ >=1) ** IFEL – inverse free electron lasers *** FEL – free electron lasers
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