Abstracts Brochure - 2nd International Particle Accelerator Conference

een proposed to mitigate these instabilities in the
CERN SPS ring. The design of feedback systems
requires the knowledge of a reduced dynamic model
of the bunch. It allows to include and quantify the
effect of noise and signal perturbations, as well as
system robustness to parameter variation.
Identification techniques are used to estimate those
models based on bunch motion measurements. In
this work we present reduced mathematical models
representing the transverse bunch dynamics and
identification techniques to extract the model
parameters based on measurements. These
techniques are validated using time domain
simulations of the bunch motion conducted using
multi-particle simulation codes. For that, different
sections of the bunch are driven by random signals,
and the vertical motion of those areas is used to
estimate the reduced model.
Funding Agency: Work is supported by the U.S.
Department of Energy under contract DE-AC02-
76SF00515 and the US LHC Accelerator Research
Program (LARP).
Sub Classification: D05 Instabilities - Processes,
Impedances, Countermeasures
Poster Panel 70
ID: 3186 - TUOAB03
Enlarging Dynamic and Momentum Aperture by
Particle Swarm Optimization, Zhenghe Bai, Weimin
Li, Lin Wang (USTC/NSRL, Hefei, Anhui) -
Particle swarm optimization (PSO) is a
computational intelligence algorithm for global
optimization. Obtaining adequate dynamic and
momentum aperture is crucial for high injection
efficiency and long beam lifetime in low emittance
electron storage rings. Different from nonlinear
driving terms optimization, we have made direct
optimization of dynamic and momentum aperture by
PSO algorithm. It is critical to make a criterion for
comparison of dynamic and momentum aperture
tracking results in the direct optimization procedure.
Thus, in this paper we first propose a quantitative
criterion of dynamic aperture. Then we apply PSO
to the optimization of chromatic and harmonic
sextupoles to find the optimum sextupole settings
for enlarging the dynamic aperture. Taking the
momentum aperture into consideration, we make
joint optimization of dynamic and momentum
aperture. Also, the momentum aperture has its
quantitative criterion. As an example of application,
the dynamic and momentum aperture of an FBA
lattice studied in the design of storage ring of Hefei
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Advanced Light Source were optimized, and the
results have shown the power of PSO algorithm.
Sub Classification: D06 Code Developments and
Simulation Techniques
Poster Panel 71
ID: 3144 - WEPC097
Calculation of High Frequency Fields in
Resonant Cavities Based on Perturbation Theory,
Korinna Brackebusch, Hans-Walter Glock, Ursula
van Rienen (Rostock University, Rostock) - The
knowledge of the eigenmodes of resonant
accelerator cavities is essential for the determination
of their performance characteristics, comprising
resonant frequencies and field distributions inside
the cavities. Apart from the material properties the
eigenmodes of a cavity depend on its geometry. In
spite of the high elaborateness during the complex
fabrication process, minor deviations of the actual
cavity shape from the desired one are inevitable.
Moreover, especially superconducting cavities are
subject to extreme operating conditions that may
cause deformations of their shape. Any geometry
perturbation results in a shift of the resonant
frequencies and modified field distributions. In this
paper, we will analyze a generalization of Slater's
theorem proposed in literature. The method should
allow for the calculation of resonant frequencies and
field distributions of a slightly perturbed cavity by
using a set of precomputed eigenmodes of the
unperturbed cavity. We will evaluate the
practicability of the method by applying it to cavity
geometries for which the eigenmodes are
analytically known, ascertain the effort of
reasonable calculation results and describe its
limitations.
Funding Agency: Work supported by Federal
Ministry for Research and Education BMBF under
contracts 05H09HR5 and 05K10HRC.
Sub Classification: D06 Code Developments and
Simulation Techniques
Poster Panel 72
ID: 4312 - WEPC117
A Matrix Presentation for a Beam Propagator
including Particles Spin, Michael Kosovtsov,
Serge Andrianov, Andrey Ivanov (St. Petersburg
State University, St. Petersburg) - Particles beam
dynamics in magnetic and electrical fields with spin
is discussed. This approach provides a constructive
method of matrix presentation derivation for a beam
propagator in magnetic and electrical fields. The
beam propagator is evaluated in according to the