Abstracts Brochure - CERN

WEPCH — Poster Session 28-Jun-06 16:00 - 18:00
Analysis of Radiative Effects in the Electron Emission from the Photocathode and in the
Acceleration inside the RF Cavity of a Photoinjector Using the 3D Numerical Code RETAR
The three-dimensional fully relativistic and
self-consistent code RETAR has been developed
to model the dynamics of high-brightness
electron beams and in particular to assess
the importance of the retarded radiative
V. Petrillo, C. Maroli (Universita’ degli Studi di Milano) G. Alberti
(Università degli Studi di Milano) A. Bacci, A. Rossi, L. Serafini
(INFN-Milano) M. Ferrario (INFN/LNF)
part of the emitted electromagnetic fields in all conditions where the electrons experience strong accelerations. In this
analysis we evaluate the radiative energy losses in the electron emission process from the photocathode of an injector,
during the successive acceleration of the electron beam in the RF cavity and the focalization due to the magnetic field
of the solenoid, taking also into account the e.m. field of the laser illuminating the cathode. The analysis is specifically
carried out with parameters of importance in the framework of the SPARC and PLASMONX projects.
Virtual Accelerator as an Operation Tool at J-PARC 3 GeV Rapid-cycle Synchrotron (RCS)
We developed a virtual accelerator based on
EPICS for 3 GeV Rapid-Cycle Synchrotron
(RCS) in J-PARC. It is important to have an
on-line model of optics parameters, such as
tunes, Twiss parameters, dispersion func-
H. Harada, K. Shigaki (Hiroshima University) K. Furukawa (KEK)
H. Hotchi, F. Noda, H. Sako (JAEA/J-PARC) S. Machida (CCLRC/
RAL/ASTeC)
tion, at the commissioning stage in a high intensity proton machine. It gives a strong feedback for the RCS operation
as a commissioning tool as well as for the studies of beam dynamics issues. Beam position monitors with finite resolutions,
a transverse exciter to measure the betatron frequency, and a RF system with variable frequency to simulate
off-momentum optics have been implemented into the system. The virtual accelerator system itself and some results
of beam dynamics studies will be presented.
Analysis of the Symmetry in Accelerating Structures with Group Theory
Many rf cavities for modern accelerators have
a variety of symmetry. There is a question as S. Sakanaka (KEK)
to what is the connection between the symmetry
of a cavity and of its eigenmodes. This can be clarified* using the representation theory of groups. The
geometric symmetry of a cavity can be expressed by a group of symmetry operations. The structure of this group
can be represented by a set of matrices called representation. The group is associated with several irreducible representations
which can express possible patterns of transformations under the symmetry operations. The irreducible
representations are very suitable to express the symmetry of each eigenmode. This method can be used to improve
the understanding of non-axially symmetric structures. In this paper, this method is first explained, and then, it is
extended to the application of symmetric periodic structures.
*S. Sakanaka, Phys. Rev. ST Accel. Beams 8, 072002 (2005).
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