IPAC2019 - List of Authors (Yang, P.H.)

Paper	Title	Page
MOPGW045	A Fast Method for Multi-Objective Nonlinear Dynamics Optimization of a Storage Ring	190
	J.J. Tan, Z.H. Bai, W. Li, L. Wang, P.H. Yang USTC/NSRL, Hefei, Anhui, People’s Republic of China
	Multi-objective evolutionary algorithms (MOEAs), including multi-objective genetic algorithm and particle swarm optimization algorithm, have been widely applied in the nonlinear dynamics optimization of storage ring light sources. In the optimization, the direct tracking of objectives, which are, for example, dynamic aperture (DA) and momentum aperture, is very time-consuming. We noticed that there is some positive correlation between on- and off-momentum nonlinear dynamics performances, which can be used to reduce the computation time when applying MOEAs. In this paper, a fast method is proposed, in which a strategy is introduced to speed up the process of optimizing nonlinear dynamics using MOEAs. Taking the SSRF storage ring as an example, on- and off-momentum DAs are optimized using MOEAs with and without the fast strategy, and then a comparison is made to demonstrate the fast method.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW045
About •	paper received ※ 15 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019
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TUPGW054	Design of a Hybrid Seven-Bend-Achromat Lattice for a High-Energy Diffraction-Limited Storage Ring Using a New Optimization Method	1528
	P.H. Yang, Z.H. Bai, J.J. Tan, L. Wang, J.H. Xu USTC/NSRL, Hefei, Anhui, People’s Republic of China
	Recently, we proposed a new optimization method, with nonlinear dynamics indicators considered in the linear optics design, for designing hybrid multi-bend-achromat (MBA) lattices. With this method, two hybrid MBA lattices for medium-low-energy diffraction limited storage rings (DLSRs) have been designed, showing remarkable effectiveness in improving nonlinear dynamic performance. In this paper, we will apply this optimization method to the design of a hybrid 7BA lattice for a 6 GeV DLSR with the same circumference as that of HEPS. In the design, the strengths and arrangement of magnets of this lattice also meet the engineering requirement for HEPS. The designed lattice has a natural emittance of 34 pm·rad. The nonlinear dynamic performance is satisfactory, with a dynamic aperture of about 6 mm and 3 mm in the horizontal and vertical directions, respectively, and a dynamic momentum aperture of larger than 5%, which also shows the power of our optimization method.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW054
About •	paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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TUPGW055	Comparison of Optimization Methods for Hybrid Seven-Bend-Achromat Lattice Design	1532
SUSPFO079	use link to see paper's listing under its alternate paper code
	P.H. Yang, Z.H. Bai, J.J. Tan, L. Wang, J.H. Xu USTC/NSRL, Hefei, Anhui, People’s Republic of China
	Generally, for a hybrid multi-bend-achromat (MBA) lattice with fixed linear optics, there is little potential to further optimize the nonlinear dynamics due to limited free knobs. To obtain a hybrid MBA lattice with better nonlinear dynamics performance, it is better to consider some indicators of nonlinear dynamics as objective functions in designing the linear optics using an optimization algorithm. In this paper, integral strengths of sextupoles and natural chromaticities are used as the nonlinear dynamics indicators, and different optimization methods with both or either of the two indicators are carried out and compared. As an example, a hybrid 7BA lattice with an energy of 2.4 GeV is designed towards an emittance of less than 70 pm·rad.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW055
About •	paper received ※ 18 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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TUPGW056	Comparison of Constrained Optimization Methods for Designing a Multi-Bend Achromat Lattice	1535
	J.H. Xu, Z.H. Bai, W. Li, P.H. Yang USTC/NSRL, Hefei, Anhui, People’s Republic of China
	In the design of a multi-bend achromat (MBA) lattice for a diffraction-limited storage ring, there are usually many magnet parameters to be optimized and some stringent constraints to be satisfied. For example, to cancel out nonlinear dynamics effects, the phase advances between some sections are generally required to be set to certain values in the lattice design. For better designing a MBA lattice using an evolutionary algorithm, the handling of constraints will be important, because it is very hard to satisfy the constraints for most or even all of solutions in the early generations of the algorithm. This paper will first describe some methods for handling constraints, which are then applied to designing a hybrid 7BA lattice. The comparison of these methods shows that better lattice solutions can be obtained by including constraints into objective functions.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW056
About •	paper received ※ 23 April 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019
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TUPGW057	A Ten-Bend Achromat Lattice with Interleaved Dispersion Bumps for a Diffraction-Limited Storage Ring	1538
	P.H. Yang, Z.H. Bai, J.J. Tan, L. Wang, J.H. Xu USTC/NSRL, Hefei, Anhui, People’s Republic of China
	Recently, a multi-bend achromat (MBA) lattice concept, called the MBA with interleaved dispersion bumps (IDB-MBA), was proposed to design the HALS storage ring, which presented better performance of both on- and off-momentum nonlinear dynamics. Since the beam emittance scales inversely with the third power of the number of bending magnets, in this paper we will study a new IDB-MBA lattice with more bending magnets. It is feasible to satisfy the requirement of the IDB-MBA concept in a 10BA lattice, and an IDB-10BA lattice is then designed for a storage ring light source with an energy of 2.4 GeV. The designed lattice has an ultra-low natural emittance of 81 pm·rad, and a dynamic aperture of about 6 mm and a large dynamic momentum aperture of 6% are achieved.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW057
About •	paper received ※ 24 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

A Fast Method for Multi-Objective Nonlinear Dynamics Optimization of a Storage Ring

190

J.J. Tan, Z.H. Bai, W. Li, L. Wang, P.H. Yang
USTC/NSRL, Hefei, Anhui, People’s Republic of China

Multi-objective evolutionary algorithms (MOEAs), including multi-objective genetic algorithm and particle swarm optimization algorithm, have been widely applied in the nonlinear dynamics optimization of storage ring light sources. In the optimization, the direct tracking of objectives, which are, for example, dynamic aperture (DA) and momentum aperture, is very time-consuming. We noticed that there is some positive correlation between on- and off-momentum nonlinear dynamics performances, which can be used to reduce the computation time when applying MOEAs. In this paper, a fast method is proposed, in which a strategy is introduced to speed up the process of optimizing nonlinear dynamics using MOEAs. Taking the SSRF storage ring as an example, on- and off-momentum DAs are optimized using MOEAs with and without the fast strategy, and then a comparison is made to demonstrate the fast method.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW045

About •

paper received ※ 15 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPGW054

Design of a Hybrid Seven-Bend-Achromat Lattice for a High-Energy Diffraction-Limited Storage Ring Using a New Optimization Method

1528

P.H. Yang, Z.H. Bai, J.J. Tan, L. Wang, J.H. Xu
USTC/NSRL, Hefei, Anhui, People’s Republic of China

Recently, we proposed a new optimization method, with nonlinear dynamics indicators considered in the linear optics design, for designing hybrid multi-bend-achromat (MBA) lattices. With this method, two hybrid MBA lattices for medium-low-energy diffraction limited storage rings (DLSRs) have been designed, showing remarkable effectiveness in improving nonlinear dynamic performance. In this paper, we will apply this optimization method to the design of a hybrid 7BA lattice for a 6 GeV DLSR with the same circumference as that of HEPS. In the design, the strengths and arrangement of magnets of this lattice also meet the engineering requirement for HEPS. The designed lattice has a natural emittance of 34 pm·rad. The nonlinear dynamic performance is satisfactory, with a dynamic aperture of about 6 mm and 3 mm in the horizontal and vertical directions, respectively, and a dynamic momentum aperture of larger than 5%, which also shows the power of our optimization method.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW054

About •

paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPGW055

Comparison of Optimization Methods for Hybrid Seven-Bend-Achromat Lattice Design

1532

SUSPFO079

use link to see paper's listing under its alternate paper code

P.H. Yang, Z.H. Bai, J.J. Tan, L. Wang, J.H. Xu
USTC/NSRL, Hefei, Anhui, People’s Republic of China

Generally, for a hybrid multi-bend-achromat (MBA) lattice with fixed linear optics, there is little potential to further optimize the nonlinear dynamics due to limited free knobs. To obtain a hybrid MBA lattice with better nonlinear dynamics performance, it is better to consider some indicators of nonlinear dynamics as objective functions in designing the linear optics using an optimization algorithm. In this paper, integral strengths of sextupoles and natural chromaticities are used as the nonlinear dynamics indicators, and different optimization methods with both or either of the two indicators are carried out and compared. As an example, a hybrid 7BA lattice with an energy of 2.4 GeV is designed towards an emittance of less than 70 pm·rad.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW055

About •

paper received ※ 18 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPGW056

Comparison of Constrained Optimization Methods for Designing a Multi-Bend Achromat Lattice

1535

J.H. Xu, Z.H. Bai, W. Li, P.H. Yang
USTC/NSRL, Hefei, Anhui, People’s Republic of China

In the design of a multi-bend achromat (MBA) lattice for a diffraction-limited storage ring, there are usually many magnet parameters to be optimized and some stringent constraints to be satisfied. For example, to cancel out nonlinear dynamics effects, the phase advances between some sections are generally required to be set to certain values in the lattice design. For better designing a MBA lattice using an evolutionary algorithm, the handling of constraints will be important, because it is very hard to satisfy the constraints for most or even all of solutions in the early generations of the algorithm. This paper will first describe some methods for handling constraints, which are then applied to designing a hybrid 7BA lattice. The comparison of these methods shows that better lattice solutions can be obtained by including constraints into objective functions.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW056

About •

paper received ※ 23 April 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPGW057

A Ten-Bend Achromat Lattice with Interleaved Dispersion Bumps for a Diffraction-Limited Storage Ring

1538

P.H. Yang, Z.H. Bai, J.J. Tan, L. Wang, J.H. Xu
USTC/NSRL, Hefei, Anhui, People’s Republic of China

Recently, a multi-bend achromat (MBA) lattice concept, called the MBA with interleaved dispersion bumps (IDB-MBA), was proposed to design the HALS storage ring, which presented better performance of both on- and off-momentum nonlinear dynamics. Since the beam emittance scales inversely with the third power of the number of bending magnets, in this paper we will study a new IDB-MBA lattice with more bending magnets. It is feasible to satisfy the requirement of the IDB-MBA concept in a 10BA lattice, and an IDB-10BA lattice is then designed for a storage ring light source with an energy of 2.4 GeV. The designed lattice has an ultra-low natural emittance of 81 pm·rad, and a dynamic aperture of about 6 mm and a large dynamic momentum aperture of 6% are achieved.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW057

About •

paper received ※ 24 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)