IPAC2021 - List of Authors (Wang, G.M.)

Paper	Title	Page
MOPAB039	Amplitude-Dependent Shift of Betatron Tunes and Its Relation to Long-Term Circumference Variations at NSLS-II	175
	L.H. Yu, G. Bassi, Y. Hidaka, B. Podobedov, V.V. Smaluk, G.M. Wang, X. Yang BNL, Upton, New York, USA
	The comparison of amplitude tune dependence measured for NSLSII lattices with models indicated the large change of amplitude tune dependence over time apparently can not be solely explained by magnets variation or beta function changes, but it seems can be explained by energy changes. On the other hand, the energy change required by fitting with the amplitude tune dependence change is too large to be explained by the RF frequency change and the change of the sum of correctors in the period of the measurements. To explain this apparent contradiction, our analysis shows the long term storage ring circumference change can explain the apparent energy change. Our data indeed shows a seasonal change of the amplitude tune dependence over long term observation. This clearly also indicated a relation to long term closed orbit drift. Hence the current work indicates a new strategy to study how to use amplitude tune dependence as a guideline to analyze long term lattice parameter shifts and closed orbit drift, and improve the orbit and machine performance stability.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB039
About •	paper received ※ 09 May 2021 paper accepted ※ 26 May 2021 issue date ※ 26 August 2021
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MOPAB077	Anomaly Detection in Accelerator Facilities Using Machine Learning	304
	A. Das Stanford University, Stanford, California, USA M. Borland, L. Emery, X. Huang, H. Shang, G. Shen ANL, Lemont, Illinois, USA D.F. Ratner SLAC, Menlo Park, California, USA R.M. Smith, G.M. Wang BNL, Upton, New York, USA
	Synchrotron light sources are user facilities and usually run about 5000 hours per year to support many beamlines operations in parallel. Reliability is a key parameter to evaluate machine performance. Even many facilities have achieved >95% beam reliability, there are still many hours of unscheduled downtime and every hour lost is a waste of operation costs along with a big impact on individual scheduled user experiments. Preventive maintenance on subsystems and quick recovery from machine trips are the basic strategies to achieve high reliability, which heavily depends on experts’ dedication. Recently, SLAC, APS, and NSLS-II collaborated to develop machine-learning-based approaches aiming to solve both situations, hardware failure prediction and machine failure diagnosis to find the root sources. In this paper, we report our facility operation status, development progress, and plans.
	Poster MOPAB077 [1.240 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB077
About •	paper received ※ 16 May 2021 paper accepted ※ 14 June 2021 issue date ※ 01 September 2021
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MOPAB079	Experience of the First Six Years Operations and Plans in NSlS-II	308
	G.M. Wang BNL, Upton, New York, USA
	NSLS-II is a 3 GeV third-generation synchrotron light source at BNL. The storage ring was commissioned in 2014 and began its routine operations in the December of the same year. Since then, we have been continuously installing and commissioning new insertion devices, their front-ends, and beamlines. At this point, the facility hosts 28 operating beamlines from various radiation sources, including damping wiggler, IVU, EPU, 3PW, and bending magnets for infrared beamlines. Over the past six years, the storage ring performance continuously improved, including 500 mA with limited insertion devices close due to RF power limitation and routinely 400 mA top off operation, >95% operation reliability, maintenance of beam motion short- and long-term stability. In this paper, we report NSLS-II accelerator operations experience and plans for future facility developments.
	Poster MOPAB079 [2.064 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB079
About •	paper received ※ 17 May 2021 paper accepted ※ 21 June 2021 issue date ※ 25 August 2021
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TUPAB227	Simultaneous Compensation of Phase and Amplitude Dependent Geometrical Resonances Using Octupoles	1960
	F. Plassard, Y. Hidaka, Y. Li, T.V. Shaftan, V.V. Smaluk, G.M. Wang BNL, Upton, New York, USA
	As the new generation of light sources are pushing toward diffraction limited storage rings with ultra-low emittance beams, nonlinear beam dynamics become increasingly difficult to control. It is a common practice for modern designs to use a sextupole scheme that allows simultaneous correction of natural chromaticity and energy independent, or geometrical, sextupolar resonances. However, the remaining higher order terms arising from the cross talks of the sextupole families set a strong limitation on the achievable dynamic aperture. This paper presents a simulation-based recipe to use octupoles together with this sextupole scheme to provide simultaneous self-compensation of linear amplitude dependent tune shift together with phase-dependent octupolar and higher order geometrical resonant driving terms. The correction method was built based on observations made on a simple FODO model, then applied to a realistic low emittance lattice, designed in the framework of the upgrade of the National Synchrotron Light Source II (NSLS-II).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB227
About •	paper received ※ 19 May 2021 paper accepted ※ 23 June 2021 issue date ※ 14 August 2021
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THPAB197	Enhancing Efficiency of Multi-Objective Neural-Network-Assisted Nonlinear Dynamics Lattice Optimization via 1-D Aperture Objectives & Objective Focusing	4156
	Y. Hidaka, D.A. Hidas, F. Plassard, T.V. Shaftan, G.M. Wang BNL, Upton, New York, USA
	Funding: This work is supported by U.S. DOE under Contract No. DE-SC0012704. Mutli-objective optimizers such as multi-objective genetic algorithm (MOGA) have been quite popular in discovering desirable lattice solutions for accelerators. However, even these successful algorithms can become ineffective as the dimension and range of the search space increase due to exponential growth in the amount of exploration required to find global optima. This difficulty is even more exacerbated by the resource-intensive and time-consuming tendency for the evaluations of nonlinear beam dynamics. Lately the use of surrogate models based on neural network has been drawing attention to alleviate this problem. Following this trend, to further enhance the efficiency of nonlinear lattice optimization for storage rings, we propose to replace typically used objectives with those that are less time-consuming and to focus on a single objective constructed from multiple objectives, which can maximize utilization of the trained models through local optimization and objective gradient extraction. We demonstrate these enhancements using a NSLS-II upgrade lattice candidate as an example.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB197
About •	paper received ※ 20 May 2021 paper accepted ※ 23 June 2021 issue date ※ 10 August 2021
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FRXA02	Advances in Beam Stability in Low-Emittance Synchrotron Light Sources
	G.M. Wang BNL, Upton, New York, USA
	The evolution and maturation of user applications at low-emittance light sources is driving new, more stringent requirements for electron beam stability in the source points. Long high-spatial-resolution, nano-focus, and high-energy-resolution beamlines demand that the beam orbit and envelope in their insertion devices are stabilized to a small degree of the beam size. At the same time, the capabilities of modern electronics have been advancing rapidly in the past decade, enabling revolutionary developments in broad-bandwidth feedback systems for every dimension of beam dynamics. In addition, synergies between modern beamline and accelerator controls have opened up a pathway to develop and test the first fully integrated feedback system that can counteract drifts and vibrations, allowing us to meet these tight stability requirements. In this presentation we will discuss the stability requirements for premier instruments at NSLS-II and summarize our recent developments in this area.
	Slides FRXA02 [2.914 MB]
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Paper

Title

Page

Amplitude-Dependent Shift of Betatron Tunes and Its Relation to Long-Term Circumference Variations at NSLS-II

175

L.H. Yu, G. Bassi, Y. Hidaka, B. Podobedov, V.V. Smaluk, G.M. Wang, X. Yang
BNL, Upton, New York, USA

The comparison of amplitude tune dependence measured for NSLSII lattices with models indicated the large change of amplitude tune dependence over time apparently can not be solely explained by magnets variation or beta function changes, but it seems can be explained by energy changes. On the other hand, the energy change required by fitting with the amplitude tune dependence change is too large to be explained by the RF frequency change and the change of the sum of correctors in the period of the measurements. To explain this apparent contradiction, our analysis shows the long term storage ring circumference change can explain the apparent energy change. Our data indeed shows a seasonal change of the amplitude tune dependence over long term observation. This clearly also indicated a relation to long term closed orbit drift. Hence the current work indicates a new strategy to study how to use amplitude tune dependence as a guideline to analyze long term lattice parameter shifts and closed orbit drift, and improve the orbit and machine performance stability.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB039

About •

paper received ※ 09 May 2021 paper accepted ※ 26 May 2021 issue date ※ 26 August 2021

Export •

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

MOPAB077

Anomaly Detection in Accelerator Facilities Using Machine Learning

304

A. Das
Stanford University, Stanford, California, USA
M. Borland, L. Emery, X. Huang, H. Shang, G. Shen
ANL, Lemont, Illinois, USA
D.F. Ratner
SLAC, Menlo Park, California, USA
R.M. Smith, G.M. Wang
BNL, Upton, New York, USA

Synchrotron light sources are user facilities and usually run about 5000 hours per year to support many beamlines operations in parallel. Reliability is a key parameter to evaluate machine performance. Even many facilities have achieved >95% beam reliability, there are still many hours of unscheduled downtime and every hour lost is a waste of operation costs along with a big impact on individual scheduled user experiments. Preventive maintenance on subsystems and quick recovery from machine trips are the basic strategies to achieve high reliability, which heavily depends on experts’ dedication. Recently, SLAC, APS, and NSLS-II collaborated to develop machine-learning-based approaches aiming to solve both situations, hardware failure prediction and machine failure diagnosis to find the root sources. In this paper, we report our facility operation status, development progress, and plans.

Poster MOPAB077 [1.240 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB077

About •

paper received ※ 16 May 2021 paper accepted ※ 14 June 2021 issue date ※ 01 September 2021

Export •

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

MOPAB079

Experience of the First Six Years Operations and Plans in NSlS-II

308

G.M. Wang
BNL, Upton, New York, USA

NSLS-II is a 3 GeV third-generation synchrotron light source at BNL. The storage ring was commissioned in 2014 and began its routine operations in the December of the same year. Since then, we have been continuously installing and commissioning new insertion devices, their front-ends, and beamlines. At this point, the facility hosts 28 operating beamlines from various radiation sources, including damping wiggler, IVU, EPU, 3PW, and bending magnets for infrared beamlines. Over the past six years, the storage ring performance continuously improved, including 500 mA with limited insertion devices close due to RF power limitation and routinely 400 mA top off operation, >95% operation reliability, maintenance of beam motion short- and long-term stability. In this paper, we report NSLS-II accelerator operations experience and plans for future facility developments.

Poster MOPAB079 [2.064 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB079

About •

paper received ※ 17 May 2021 paper accepted ※ 21 June 2021 issue date ※ 25 August 2021

Export •

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

TUPAB227

Simultaneous Compensation of Phase and Amplitude Dependent Geometrical Resonances Using Octupoles

1960

F. Plassard, Y. Hidaka, Y. Li, T.V. Shaftan, V.V. Smaluk, G.M. Wang
BNL, Upton, New York, USA

As the new generation of light sources are pushing toward diffraction limited storage rings with ultra-low emittance beams, nonlinear beam dynamics become increasingly difficult to control. It is a common practice for modern designs to use a sextupole scheme that allows simultaneous correction of natural chromaticity and energy independent, or geometrical, sextupolar resonances. However, the remaining higher order terms arising from the cross talks of the sextupole families set a strong limitation on the achievable dynamic aperture. This paper presents a simulation-based recipe to use octupoles together with this sextupole scheme to provide simultaneous self-compensation of linear amplitude dependent tune shift together with phase-dependent octupolar and higher order geometrical resonant driving terms. The correction method was built based on observations made on a simple FODO model, then applied to a realistic low emittance lattice, designed in the framework of the upgrade of the National Synchrotron Light Source II (NSLS-II).

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB227

About •

paper received ※ 19 May 2021 paper accepted ※ 23 June 2021 issue date ※ 14 August 2021

Export •

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

THPAB197

Enhancing Efficiency of Multi-Objective Neural-Network-Assisted Nonlinear Dynamics Lattice Optimization via 1-D Aperture Objectives & Objective Focusing

4156

Y. Hidaka, D.A. Hidas, F. Plassard, T.V. Shaftan, G.M. Wang
BNL, Upton, New York, USA

Funding: This work is supported by U.S. DOE under Contract No. DE-SC0012704.
Mutli-objective optimizers such as multi-objective genetic algorithm (MOGA) have been quite popular in discovering desirable lattice solutions for accelerators. However, even these successful algorithms can become ineffective as the dimension and range of the search space increase due to exponential growth in the amount of exploration required to find global optima. This difficulty is even more exacerbated by the resource-intensive and time-consuming tendency for the evaluations of nonlinear beam dynamics. Lately the use of surrogate models based on neural network has been drawing attention to alleviate this problem. Following this trend, to further enhance the efficiency of nonlinear lattice optimization for storage rings, we propose to replace typically used objectives with those that are less time-consuming and to focus on a single objective constructed from multiple objectives, which can maximize utilization of the trained models through local optimization and objective gradient extraction. We demonstrate these enhancements using a NSLS-II upgrade lattice candidate as an example.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB197

About •

paper received ※ 20 May 2021 paper accepted ※ 23 June 2021 issue date ※ 10 August 2021

Export •

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

FRXA02

Advances in Beam Stability in Low-Emittance Synchrotron Light Sources

G.M. Wang
BNL, Upton, New York, USA

The evolution and maturation of user applications at low-emittance light sources is driving new, more stringent requirements for electron beam stability in the source points. Long high-spatial-resolution, nano-focus, and high-energy-resolution beamlines demand that the beam orbit and envelope in their insertion devices are stabilized to a small degree of the beam size. At the same time, the capabilities of modern electronics have been advancing rapidly in the past decade, enabling revolutionary developments in broad-bandwidth feedback systems for every dimension of beam dynamics. In addition, synergies between modern beamline and accelerator controls have opened up a pathway to develop and test the first fully integrated feedback system that can counteract drifts and vibrations, allowing us to meet these tight stability requirements. In this presentation we will discuss the stability requirements for premier instruments at NSLS-II and summarize our recent developments in this area.

Slides FRXA02 [2.914 MB]

Export •

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