IPAC2011 - Table of Session: TUOAB (Beam Dynamics and Electromagnetic Fields)

Paper

Title

Page

Lattice Design of a Very Low-emittance Storage Ring for SPring-8-II

942

Y. Shimosaki, K.K. Kaneki, T. Nakamura, H. Ohkuma, J. Schimizu, K. Soutome, M. Takao
JASRI/SPring-8, Hyogo-ken, Japan

The design work for an upgrade project of the SPring-8, the SPring-8-II, is in progress. Its ultimate goal is to provide a superior brilliance of photons by reducing emittance of electrons until a diffraction limit. A multi-bend lattice has been adopted for the emittance reduction; a double-bend lattice (natural emittance of 2000 pmrad at 6 GeV), a triple-bend lattice (400 pmrad) and a quadruple-bend lattice (170 pmrad) were designed step by step for studying its feasibility*. For an additional emittance reduction, beam dynamic issues for a sextuple-bend lattice have been examined for the first candidate. In this case, the natural emittance is about 70 pmrad. The dynamic aperture has been enlarged by studying beam dynamic phenomena caused by nonlinear dispersion, nonlinear chromaticity, nonlinear resonance, etc., and by optimizing linear and nonlinear optics. The lattice design for the coming upgrade of SPring-8 will be presented in detail.
* K. Soutome et al., "Design Study of a very Low-emittance Storage Ring for the Future Upgrade Plan of SPring-8", Proc. of IPAC10, WEPEA032, p. 2555 (2010).

Slides TUOAB01 [4.812 MB]

TUOAB02

Simultaneous Long and Short Bunch Operation in an Electron Storage Ring - a Hybrid Mode based on Nonlinear Momentum Compaction

945

M. Ries, J. Feikes, A. Jankowiak, P.O. Schmid, G. Wüstefeld
HZB, Berlin, Germany

The generation of short pulses in electron storage rings is driven by different user groups like time resolved x-ray spectroscopy users or users of coherent synchrotron radiation. The required optics and operation conditions to generate this short bunches are worsening the experimental conditions, e.g. strongly reducing the average photon flux, for the regular user. Therefore short bunch operation is usually limited to dedicated user shifts. By controlling higher orders of the momentum compaction factor by higher multipoles it is possible to introduce a hybrid mode and simultaneously supplying long and short bunches*. The Metrology Light Source (MLS) has the means to control these higher orders**, therefore it is an ideal machine to investiate the feasibility of such a hybrid mode. Tracking results and first measurements will be shown.
* D. Robin et al., Proc. of EPAC08, p. 2100-2102, Genoa, Italy (2008).
** J. Feikes et al., Phys. Rev. ST Accel. Beams 14, 030705 (2011).

Slides TUOAB02 [7.817 MB]

TUOAB03

Enlarging Dynamic and Momentum Aperture by Particle Swarm Optimization

948

Z. Bai, W. Li, L. Wang
USTC/NSRL, Hefei, Anhui, People's Republic of China

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 Advanced Light Source were optimized, and the results have shown the power of PSO algorithm.

Slides TUOAB03 [0.313 MB]

Paper	Title	Page
TUOAB01	Lattice Design of a Very Low-emittance Storage Ring for SPring-8-II	942
	Y. Shimosaki, K.K. Kaneki, T. Nakamura, H. Ohkuma, J. Schimizu, K. Soutome, M. Takao JASRI/SPring-8, Hyogo-ken, Japan
	The design work for an upgrade project of the SPring-8, the SPring-8-II, is in progress. Its ultimate goal is to provide a superior brilliance of photons by reducing emittance of electrons until a diffraction limit. A multi-bend lattice has been adopted for the emittance reduction; a double-bend lattice (natural emittance of 2000 pmrad at 6 GeV), a triple-bend lattice (400 pmrad) and a quadruple-bend lattice (170 pmrad) were designed step by step for studying its feasibility. For an additional emittance reduction, beam dynamic issues for a sextuple-bend lattice have been examined for the first candidate. In this case, the natural emittance is about 70 pmrad. The dynamic aperture has been enlarged by studying beam dynamic phenomena caused by nonlinear dispersion, nonlinear chromaticity, nonlinear resonance, etc., and by optimizing linear and nonlinear optics. The lattice design for the coming upgrade of SPring-8 will be presented in detail. K. Soutome et al., "Design Study of a very Low-emittance Storage Ring for the Future Upgrade Plan of SPring-8", Proc. of IPAC10, WEPEA032, p. 2555 (2010).
	Slides TUOAB01 [4.812 MB]

TUOAB02	Simultaneous Long and Short Bunch Operation in an Electron Storage Ring - a Hybrid Mode based on Nonlinear Momentum Compaction	945
	M. Ries, J. Feikes, A. Jankowiak, P.O. Schmid, G. Wüstefeld HZB, Berlin, Germany
	The generation of short pulses in electron storage rings is driven by different user groups like time resolved x-ray spectroscopy users or users of coherent synchrotron radiation. The required optics and operation conditions to generate this short bunches are worsening the experimental conditions, e.g. strongly reducing the average photon flux, for the regular user. Therefore short bunch operation is usually limited to dedicated user shifts. By controlling higher orders of the momentum compaction factor by higher multipoles it is possible to introduce a hybrid mode and simultaneously supplying long and short bunches. The Metrology Light Source (MLS) has the means to control these higher orders, therefore it is an ideal machine to investiate the feasibility of such a hybrid mode. Tracking results and first measurements will be shown. D. Robin et al., Proc. of EPAC08, p. 2100-2102, Genoa, Italy (2008). ** J. Feikes et al., Phys. Rev. ST Accel. Beams 14, 030705 (2011).
	Slides TUOAB02 [7.817 MB]

TUOAB03	Enlarging Dynamic and Momentum Aperture by Particle Swarm Optimization	948
	Z. Bai, W. Li, L. Wang USTC/NSRL, Hefei, Anhui, People's Republic of China
	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 Advanced Light Source were optimized, and the results have shown the power of PSO algorithm.
	Slides TUOAB03 [0.313 MB]