IPAC2021 - List of Authors (Xiao, A.)

Paper	Title	Page
MOPAB043	Validation of APS-U Beam Dynamics Using 6-GeV APS Beam	189
	L. Emery, P.S. Kallakuri, R.R. Lindberg, A. Xiao ANL, Lemont, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. Several beam measurements at the Advanced Photon Sources were done with a lowered-energy beam of 6 GeV in order to verify or validate calculation codes and some predictions for the APS-U. Though the APS lattice is obviously different from that of the APS-U some aspects of the beams at 6 GeV are similar, for example, the synchrotron radiation damping rate. At 6 GeV, one can also store more current and run with a higher rf bucket allowing the characterization of larger momentum aperture lattices. We report measurements (or plans of measurements) on general instabilities thresholds, lifetime, and other subtle effects. The important topic of ion instabilities at 6 GeV is covered in a separate paper by J. Calvey at this conference.
	Poster MOPAB043 [0.829 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB043
About •	paper received ※ 20 May 2021 paper accepted ※ 23 June 2021 issue date ※ 10 August 2021
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MOPAB059	Tools for Use of Generalized Gradient Expansions in Accelerator Simulations	253
	M. Borland, R.R. Lindberg, R. Soliday, A. Xiao ANL, Lemont, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. A common assumption in simulation of accelerators is that the magnets can be approximated using a hard-edge model, perhaps with some edge effects implemented in an impulse approximation. This is usually a good assumption but ignores details of the longitudinal variation of the magnetic fields, which makes it straightforward to implement symplectic tracking. Use of generalized gradient expansions* provides an alternative approach that can suppress numerical deficiencies that may be present in computed or measured 3D field maps. However, the computation of the expansions is not particularly straightforward. In this note, we describe several recently-developed tools that make this process fairly painless and allow tracking with such expansions in the program ELEGANT*. We show several examples of using the tools for simulations related to the Advanced Photon Source Upgrade. M. Venturini et al., NIM A 427, 387 (1999). ** M. Borland, Advanced Photon Source LS-287, September 2000
	Poster MOPAB059 [4.311 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB059
About •	paper received ※ 17 May 2021 paper accepted ※ 26 May 2021 issue date ※ 18 August 2021
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MOPAB214	Linear Optics Measurement for the APS Ring with Turn-by-Turn BPM Data	707
	X. Huang, V. Sajaev, Y.P. Sun, A. Xiao ANL, Lemont, Illinois, USA
	We measure the linear optics of the APS storage ring from turn-by-turn BPM data taken when the beam is excited with an injection kicker. Decoherence due to chromaticity and amplitude-dependent detuning is observed and compared to theoretic predictions. Independent component analysis is used to analyze the data, which separates the betatron normal modes and synchrotron motion, despite contamination of bad BPMs. The beta functions and phase advances are subsequently obtained. The method is used to study the linear optics perturbation of an insertion device.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB214
About •	paper received ※ 12 May 2021 paper accepted ※ 09 June 2021 issue date ※ 01 September 2021
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THPAB050	Compact Hybrid Planar Permanent Magnet Undulator Design for the APS Upgrade	3859
	M. Abliz, M. Borland, J.H. Grimmer, J.S. Kerby, M. Ramanathan, A. Xiao ANL, Lemont, Illinois, USA
	We report on the successful design of a compact 28-mm period hybrid planar permanent magnet (HPPM) undulator for the Advanced Photon Source Upgrade (APS-U) project. The design produces a peak field of 9750 G at a gap of 8.5 mm, with a pole width reduced to 35 mm as compared to the planar undulators currently in use at the Advanced Photon Source. The design includes a detailed investigation into the origin of the HPPM undulator demagnetization. We report on a finding of an optimization method that reduces the demagnetization field and increases the field at the gap center of the design. It includes an optimization of the pole edges to increase the field and decrease roll-off in the transverse direction. Further design optimizations include analyses of the mechanical assembly tolerances and comparison with the original design before building the device. Beam physics analyses included kick-map analysis, dynamic acceptance (DA), local momentum acceptance (LMA), and Touschek lifetime of this design were performed with the 42-pm lattice of the APS-U. Detailed magnetic design, effective field, field roll-off, magnetic force, and tracking results are reported.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB050
About •	paper received ※ 14 May 2021 paper accepted ※ 01 September 2021 issue date ※ 21 August 2021
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THPAB051	Vertical Septum Magnet Design for the APS Upgrade	3862
	M. Abliz, M. Borland, H. Cease, G. Decker, A.K. Jain, M.S. Jaski, M. Kasa, J.S. Kerby, U. Wienands, A. Xiao ANL, Lemont, Illinois, USA J.W. Amann SLAC, Menlo Park, California, USA D.J. Harding Fermilab, Batavia, Illinois, USA
	The vertical injection scheme proposed for the APS Upgrade (APS-U) Project requires a challenging septum magnet that must meet stringent beam physics, magnetic field leakage, and vacuum requirements. The current iteration of this magnet design includes an enlarged stored-beam chamber aperture of 9 mm x 12 mm and a reduction of the septum thickness to 1.5 mm. The enlarged aperture accommodates a non-evaporable getter (NEG)-coated stored beam chamber to better achieve the required vacuum. A prototype septum magnet has been built and measurements confirm the cancellation of a peak leakage field even though the value is six times larger than the design. The leakage field measured at the upstream (US) end cancels the downstream (DS) end as was expected by design. The measured and simulated leakage field and the stored beam trajectories are reported.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB051
About •	paper received ※ 14 May 2021 paper accepted ※ 01 September 2021 issue date ※ 27 August 2021
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Validation of APS-U Beam Dynamics Using 6-GeV APS Beam

189

L. Emery, P.S. Kallakuri, R.R. Lindberg, A. Xiao
ANL, Lemont, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
Several beam measurements at the Advanced Photon Sources were done with a lowered-energy beam of 6 GeV in order to verify or validate calculation codes and some predictions for the APS-U. Though the APS lattice is obviously different from that of the APS-U some aspects of the beams at 6 GeV are similar, for example, the synchrotron radiation damping rate. At 6 GeV, one can also store more current and run with a higher rf bucket allowing the characterization of larger momentum aperture lattices. We report measurements (or plans of measurements) on general instabilities thresholds, lifetime, and other subtle effects. The important topic of ion instabilities at 6 GeV is covered in a separate paper by J. Calvey at this conference.

Poster MOPAB043 [0.829 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB043

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)

MOPAB059

Tools for Use of Generalized Gradient Expansions in Accelerator Simulations

253

M. Borland, R.R. Lindberg, R. Soliday, A. Xiao
ANL, Lemont, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
A common assumption in simulation of accelerators is that the magnets can be approximated using a hard-edge model, perhaps with some edge effects implemented in an impulse approximation. This is usually a good assumption but ignores details of the longitudinal variation of the magnetic fields, which makes it straightforward to implement symplectic tracking. Use of generalized gradient expansions* provides an alternative approach that can suppress numerical deficiencies that may be present in computed or measured 3D field maps. However, the computation of the expansions is not particularly straightforward. In this note, we describe several recently-developed tools that make this process fairly painless and allow tracking with such expansions in the program ELEGANT**. We show several examples of using the tools for simulations related to the Advanced Photon Source Upgrade.
* M. Venturini et al., NIM A 427, 387 (1999).
** M. Borland, Advanced Photon Source LS-287, September 2000

Poster MOPAB059 [4.311 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB059

About •

paper received ※ 17 May 2021 paper accepted ※ 26 May 2021 issue date ※ 18 August 2021

Export •

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

MOPAB214

Linear Optics Measurement for the APS Ring with Turn-by-Turn BPM Data

707

X. Huang, V. Sajaev, Y.P. Sun, A. Xiao
ANL, Lemont, Illinois, USA

We measure the linear optics of the APS storage ring from turn-by-turn BPM data taken when the beam is excited with an injection kicker. Decoherence due to chromaticity and amplitude-dependent detuning is observed and compared to theoretic predictions. Independent component analysis is used to analyze the data, which separates the betatron normal modes and synchrotron motion, despite contamination of bad BPMs. The beta functions and phase advances are subsequently obtained. The method is used to study the linear optics perturbation of an insertion device.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB214

About •

paper received ※ 12 May 2021 paper accepted ※ 09 June 2021 issue date ※ 01 September 2021

Export •

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

THPAB050

Compact Hybrid Planar Permanent Magnet Undulator Design for the APS Upgrade

3859

M. Abliz, M. Borland, J.H. Grimmer, J.S. Kerby, M. Ramanathan, A. Xiao
ANL, Lemont, Illinois, USA

We report on the successful design of a compact 28-mm period hybrid planar permanent magnet (HPPM) undulator for the Advanced Photon Source Upgrade (APS-U) project. The design produces a peak field of 9750 G at a gap of 8.5 mm, with a pole width reduced to 35 mm as compared to the planar undulators currently in use at the Advanced Photon Source. The design includes a detailed investigation into the origin of the HPPM undulator demagnetization. We report on a finding of an optimization method that reduces the demagnetization field and increases the field at the gap center of the design. It includes an optimization of the pole edges to increase the field and decrease roll-off in the transverse direction. Further design optimizations include analyses of the mechanical assembly tolerances and comparison with the original design before building the device. Beam physics analyses included kick-map analysis, dynamic acceptance (DA), local momentum acceptance (LMA), and Touschek lifetime of this design were performed with the 42-pm lattice of the APS-U. Detailed magnetic design, effective field, field roll-off, magnetic force, and tracking results are reported.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB050

About •

paper received ※ 14 May 2021 paper accepted ※ 01 September 2021 issue date ※ 21 August 2021

Export •

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

THPAB051

Vertical Septum Magnet Design for the APS Upgrade

3862

M. Abliz, M. Borland, H. Cease, G. Decker, A.K. Jain, M.S. Jaski, M. Kasa, J.S. Kerby, U. Wienands, A. Xiao
ANL, Lemont, Illinois, USA
J.W. Amann
SLAC, Menlo Park, California, USA
D.J. Harding
Fermilab, Batavia, Illinois, USA

The vertical injection scheme proposed for the APS Upgrade (APS-U) Project requires a challenging septum magnet that must meet stringent beam physics, magnetic field leakage, and vacuum requirements. The current iteration of this magnet design includes an enlarged stored-beam chamber aperture of 9 mm x 12 mm and a reduction of the septum thickness to 1.5 mm. The enlarged aperture accommodates a non-evaporable getter (NEG)-coated stored beam chamber to better achieve the required vacuum. A prototype septum magnet has been built and measurements confirm the cancellation of a peak leakage field even though the value is six times larger than the design. The leakage field measured at the upstream (US) end cancels the downstream (DS) end as was expected by design. The measured and simulated leakage field and the stored beam trajectories are reported.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB051

About •

paper received ※ 14 May 2021 paper accepted ※ 01 September 2021 issue date ※ 27 August 2021

Export •

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