Abstracts Brochure - CERN

WEPCH — Poster Session 28-Jun-06 16:00 - 18:00
Linear and Nonlinear Coupling Using Decoupling Transformations
Linear coupling in a storage ring is conveniently
analyzed in terms of transformations A. Wolski, A. Sessler (LBNL)
that put the single-turn map into block-diagonal
form. Such a transformation allows us to define new variables, in which the dynamics are uncoupled. Thus, for
example, the symplectic conditions are simply that the phase area in each of the uncoupled variables is preserved. In
principle, a similar approach may be taken to nonlinear coupling; we discuss such an approach in this paper, giving
some simple illustrations of the ideas, based on the well-known techniques of normal form analysis. We also discuss
some obstacles to finding a nonlinear decoupling transformation in the general case.
SABER Optical Design
SABER, the South Arc Beam Experimental
Region, is a proposed new beam line facility R.A. Erickson, K.L.F. Bane, Y. Nosochkov (SLAC)
designed to replace the Final Focus Test Beam
at SLAC. In this paper, we outline the optical design features and beam parameters now envisioned for SABER. A
magnetic chicane to compress positron bunches for SABER and a bypass line that could transport electrons or positrons
from the two-thirds point of the linac to SABER, bypassing the LCLS systems, are also discussed.
Precision Measurement and Improvement of Optics for e+, e − Storage Rings
Through horizontal and vertical excitations,
we have been able to make a precision mea- Y.T. Yan, Y. Cai (SLAC)
surement of linear geometric optics parameters
with a Model-Independent Analysis (MIA). We have also been able to build up a computer model that matches
the real accelerator in linear geometric optics with an SVD-enhanced Least-square fitting process. Recently, with the
addition of longitudinal excitation, we are able to build up a computer virtual machine that matches the real accelerators
in linear optics including dispersion without additional fitting variables. With this optics-matched virtual
machine, we are able to find solutions that make changes of many normal and skew quadrupoles for machine optics
improvement. It has made major contributions to improve PEP-II optics and luminosity. Examples from application
to PEP-II machines will be presented.
Measurements and Modeling of Eddy Current Effects in BNL’s AGS Booster
Recent beam experiments at BNL’s AGS
Booster have enabled us to study in more
detail the effects of eddy currents on the lattice
structure and our control over the basic
K.A. Brown, L. Ahrens, C.J. Gardner, J. Glenn, M. Harvey, W. Meng,
K. Zeno (BNL)
lattice parameters of betatron tune and chromaticity. The Booster is capable of operating at ramp rates as high as 8
T/sec. At these ramp rates eddy currents in the vacuum chambers have significant effects on the fields and gradients
seen by the beam as it is accelerated. The Booster was designed with these effects in mind and to help control the
field uniformity and linearity in the Booster Dipoles special vacuum chambers were designed with current windings
289
WEPCH060
WEPCH061
WEPCH062
WEPCH063