Abstracts Brochure - CERN

WEPCH — Poster Session 28-Jun-06 16:00 - 18:00
Study of the Effect of Multipolar Components in the SPARC Emittance Compensation
Gun Solenoid
The SPARC photoinjector rf gun requires a
solenoid immediately downstream for emittance
compensation. The analysis of the measured
solenoid magnetic maps shows the existence
of multipolar components added to
the pure solenoid field. The effect of these
C. Ronsivalle, G. Dattoli, L. Picardi, M. Quattromini (ENEA C.R.
Frascati) G. Bazzano (CNAO Foundation) M. Ferrario, M. Migliorati,
L. Palumbo, M.A. Preger, C. Sanelli (INFN/LNF) P. Musumeci
(INFN-Roma) J.B. Rosenzweig (UCLA)
added fields on beam dynamics and possible correction schemes have been studied from the theoretical point of view
and by numerical calculations based on PARMELA/TREDI codes. An accurate 3D numerical modelization by using
CST EM Studio has been done, in order to investigate the source of these multipolar components and to suggest some
design modifications aimed to reduce their magnitude. The results of this study are presented here.
Longitudinal Coherent Oscillation Induced in Quasi-isochronous Ring
Noise sources, which excite longitudinal coherent
oscillation is discussed. Especially in
a quasi-isochronous electron storage ring an
identification of the noise sources is impor-
Y. Shoji, Y. Hisaoka, T. Mitsui (NewSUBARU/SPring-8, Laboratory
of Advanced Science and Technology for Industry (LASTI))
tant to obtain an extremely short bunch. One possible source is a well-known rf noise in the acceleration field. The
other is a magnetic field ripple, which changes a path-length for a revolution. The analytical formula for the longitudinal
coherent oscillation is explained. It contains the path-length oscillation, which had never been considered. The
third is a beam itself, probably be a coherent radiation loss. The driving term is not symmetric along the energy axis,
then the oscillation amplitude depends on the higher order momentum compaction factor.
Matrix Formulation for Hamilton Perturbation Theory of Linearly Coupled Betatron Motion
Linear coupled motion in a circular accelerator
was successfully parametrized through M. Takao (JASRI/SPring-8)
the transfer matrix approach, where normal
mode Twiss and coupling parameters are defined as an extension of Courand and Snyder formulation. However it is
not straightforward to assign analytical expressions to the coupling parameters. On the other hand the coupled motion
was analytically solved by the Hamilton perturbation theory, which ingeniously describes the resonance phenomena.
In the perturbation theory, however, the symplectic structure of the coupled motion is obscure in turn. Hence, for the
purpose of combining both the theories with each other with keeping the respective virtues, we develop the matrix
formulation based on the Hamilton perturbation theory. Since we have already known the solution of equation of
motion, we can construct the transfer matrix in terms of the solution. Thus we formulate the betatron motion with
linear coupling resonance in analytic and symplectic manner. As an application of the formulation, we investigate
the two-dimensional beam ellipse in an electron storage ring.
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