IPAC2015 - List of Authors (Xiao, A.)

Paper	Title	Page
MOPMA007	Tracking Studies of a Higher-Harmonic Bunch-Lengthening Cavity for the Advanced Photon Source Upgrade	543
	M. Borland, T.G. Berenc, R.R. Lindberg, A. Xiao ANL, Argonne, Ilinois, 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. The Advanced Photon Source (APS) multi-bend achromat (MBA) lattice will require a bunch-lengthening cavity to decrease the effects of Touschek scattering on the beam lifetime and of intrabeam scattering on the beam emittance. Using ELEGANT, we've performed tracking studies of a passive, i.e. beam-driven, fourth-harmonic cavity in the MBA lattice, including the predicted longitudinal impedance of the ring. The studies include an exploration of the required detuning and loaded Q of the main rf cavities and the harmonic cavity in order to stabilize the beam and achieve significant lengthening. We also studied the effects of bunch population variation and missing bunches. The computed bunch profiles are used for computation of the Touschek lifetime, verifying the beneficial effects in detail.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMA007
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MOPMA009	Improvements in Modeling of Collective Effects in ELEGANT	549
	M. Borland, R.R. Lindberg, A. Xiao ANL, Argonne, Ilinois, 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. ELEGANT has long had the ability to model collective effects in various ways, including beam-driven cavity modes, short-range wakes, and coherent synchrotron radiation. Recently, we made improvements specifically targeting simulations that require multiple bunches in storage rings. The ability to simulate long-range, non-resonant wakes was added, which can be used for example to study the effect of the resistive wall wake and multibunch instabilities. We also improved the implementation of short-range and resonant wakes to make them more efficient for multibunch simulations. Finally, improvements in the parallel efficiency were made that allow taking advantage of larger parallel resources.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMA009
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MOPMA012	Intra-Beam and Touschek Scattering Computations for Beam with Non-Gaussian Longitudinal Distributions	559
	A. Xiao, M. Borland ANL, Argonne, Ilinois, 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 Both intra-beam scattering (IBS) and the Touschek effect become prominent for multi-bend-achromat- (MBA-) based ultra-low-emittance storage rings. To mitigate the transverse emittance degradation and obtain a reasonably long beam lifetime, a higher harmonic rf cavity (HHC) is often proposed to lengthen the bunch. The use of such a cavity results in a non-gaussian longitudinal distribution. However, common methods for computing IBS and Touschek scattering assume Gaussian distributions. Modifications have been made to several simulation codes that are part of the {\tt elegant} toolkit to allow these computations for arbitrary longitudinal distributions. After describing these modifications, we review the results of detailed simulations for the proposed hybrid seven-bend-achromat (H7BA) upgrade lattice for the Advanced Photon Source.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMA012
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MOPMA013	Experience with Round Beam Operation at the Advanced Photon Source	562
	A. Xiao, L. Emery, V. Sajaev, B.X. Yang ANL, Argonne, Ilinois, 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 Very short Touschek lifetime becomes a common issue for next-generation ultra-low emittance storage ring light sources. In order to reach a longer beam lifetime, such a machine often requires operating with a vertical-to-horizontal emittance ratio close to an unity, i.e. a ‘‘round beam''. In tests at the APS storage ring, we determined how a round beam can be reached experimentally. Some general issues, such as beam injection, optics measurement and corrections, and orbit correction have been tested also. To demonstrate that a round beam was achieved, the beam size ratio is calibrated using beam lifetime measurement.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMA013
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TUPJE064	Calibration of Fast Fiber-Optic Beam Loss Monitors for the Advanced Photon Source Storage Ring Superconducting Undulators	1780
	J.C. Dooling, K.C. Harkay, Y. Ivanyushenkov, V. Sajaev, A. Xiao ANL, Argonne, Ilinois, USA A. Vella University of Illinois at Urbana-Champaign, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, under contract number DE-AC02-06CH11357. We report on the calibration and use of fast fiber-optic (FO) beam loss monitors (BLMs) in the Advanced Photon Source storage ring (SR). A superconducting undulator prototype (SCU0) has been operating in SR Sector 6 since the beginning of CY2013, and another undulator SCU1 (a 1.1-m length undulator that is three times the length of SCU0) is scheduled for installation in Sector 1 in 2015. The SCU0 main coil often quenches during beam dumps. MARS simulations have shown that relatively small beam loss (<1 nC) can lead to temperature excursions sufficient to cause quenching when the SCU0 windings are near critical current. To characterize local beam losses, high-purity fused-silica FO cables were installed in Sector 6 next to the SCU0 cryostat and in Sector 1 where SCU1 will be installed. These BLMs aid in the search for operating modes that protect the SCU structures from beam-loss-induced quenching. In this paper, we describe the BLM calibration process that included deliberate beam dumps at locations of BLMs. We also compare beam dump events where SCU0 did and did not quench.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPJE064
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TUPJE069	Fast Injection System R&D for the APS Upgrade	1797
	F. Lenkszus, J. Carwardine, A.R. Cours, G. Decker, L.H. Morrison, X. Sun, J. Wang, F. Westferro, A. Xiao, C. Yao ANL, Argonne, Ilinois, USA A. Krasnykh SLAC, Menlo Park, California, USA
	Funding: Results in this report are derived from work performed at Argonne National Laboratory. Argonne is operated by UChicago Argonne, LLC, for the U.S. Department of Energy under contract DE-AC02-06CH11357. The MBA upgrade for the APS will operate with bunch swap out and on axis injection. The planned 324 bunch fill pattern places difficult demands on the injection and extraction kickers. The present concept uses dual stripline kickers driven by high Voltage pulsers. Minimizing perturbation on adjacent bunches requires very fast rise and fall times with relatively narrow ~20 nsec, 15 kV pulses. To achieve these requirements we have initiated a multifaceted R&D program. The R&D includes the HV pulser, stripline kicker and HV feedthrough. We have purchased a commercial dual channel HV pulser and are evaluating its performance and reliability. In addition, we are investigating the feasibility of using nonlinear ferrite loaded coaxial cables (shockwave transmission line) to sharpen the leading and trailing edges of high voltage pulses. We are also developing a prototype kicker and high voltage feedthrough. The requirements for injection and extraction, progress on prototype development and results of our HV pulser investigations will be reported.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPJE069
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TUPJE075	Simulation Study of Injection Performance for the Advanced Photon Source Upgrade	1816
	A. Xiao, V. Sajaev ANL, Argonne, Ilinois, 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 vertical on-axis injection scheme has been proposed for the hybrid seven-bend-achromat (H7BA) Advanced Photon Source upgrade (APSU) lattice. In order to evaluate the injection performance, various errors, such as injection beam jitter, optical mismatch and errors, and injection element errors have been investigated and their significance has been discovered. Injection efficiency is then simulated under different error levels. Based on these simulation results, specifications and an error-budget for individual systems have been defined.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPJE075
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WEPTY014	Development of Fast Kickers for the APS MBA Upgrade	3286
	C. Yao, J. Carwardine, A.R. Cours, F. Lenkszus, R.R. Lindberg, L.H. Morrison, X. Sun, J. Wang, F. Westferro, A. Xiao ANL, Argonne, Ilinois, USA
	Funding: *Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357. The APS multi-bend achromat (MBA) upgrade storage ring will support two bunch fill patterns: a 48-singlets and a 324-singlets. A “swap out” injection scheme is adopted. In order to minimize the beam loss and residual oscillation of injected beam and to minimize the perturbation of stored beam during a swap-on injection, the rise, fall, and flat-top parts of the kicker pulse must be held within a 22.8-ns interval. Traditional ferrite-core-type kickers can’t meet the timing requirements; therefore, we decided to use stripline-type kickers. We have completed a preliminary design of a prototype kicker geometry. Procurement of the pulser supply and other components of an evaluation system is under way. We report the specification and design of the fast kicker and current status.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY014
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Tracking Studies of a Higher-Harmonic Bunch-Lengthening Cavity for the Advanced Photon Source Upgrade

543

M. Borland, T.G. Berenc, R.R. Lindberg, A. Xiao
ANL, Argonne, Ilinois, 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.
The Advanced Photon Source (APS) multi-bend achromat (MBA) lattice will require a bunch-lengthening cavity to decrease the effects of Touschek scattering on the beam lifetime and of intrabeam scattering on the beam emittance. Using ELEGANT, we've performed tracking studies of a passive, i.e. beam-driven, fourth-harmonic cavity in the MBA lattice, including the predicted longitudinal impedance of the ring. The studies include an exploration of the required detuning and loaded Q of the main rf cavities and the harmonic cavity in order to stabilize the beam and achieve significant lengthening. We also studied the effects of bunch population variation and missing bunches. The computed bunch profiles are used for computation of the Touschek lifetime, verifying the beneficial effects in detail.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMA007

Export •

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

MOPMA009

Improvements in Modeling of Collective Effects in ELEGANT

549

M. Borland, R.R. Lindberg, A. Xiao
ANL, Argonne, Ilinois, 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.
ELEGANT has long had the ability to model collective effects in various ways, including beam-driven cavity modes, short-range wakes, and coherent synchrotron radiation. Recently, we made improvements specifically targeting simulations that require multiple bunches in storage rings. The ability to simulate long-range, non-resonant wakes was added, which can be used for example to study the effect of the resistive wall wake and multibunch instabilities. We also improved the implementation of short-range and resonant wakes to make them more efficient for multibunch simulations. Finally, improvements in the parallel efficiency were made that allow taking advantage of larger parallel resources.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMA009

Export •

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

MOPMA012

Intra-Beam and Touschek Scattering Computations for Beam with Non-Gaussian Longitudinal Distributions

559

A. Xiao, M. Borland
ANL, Argonne, Ilinois, 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
Both intra-beam scattering (IBS) and the Touschek effect become prominent for multi-bend-achromat- (MBA-) based ultra-low-emittance storage rings. To mitigate the transverse emittance degradation and obtain a reasonably long beam lifetime, a higher harmonic rf cavity (HHC) is often proposed to lengthen the bunch. The use of such a cavity results in a non-gaussian longitudinal distribution. However, common methods for computing IBS and Touschek scattering assume Gaussian distributions. Modifications have been made to several simulation codes that are part of the {\tt elegant} toolkit to allow these computations for arbitrary longitudinal distributions. After describing these modifications, we review the results of detailed simulations for the proposed hybrid seven-bend-achromat (H7BA) upgrade lattice for the Advanced Photon Source.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMA012

Export •

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

MOPMA013

Experience with Round Beam Operation at the Advanced Photon Source

562

A. Xiao, L. Emery, V. Sajaev, B.X. Yang
ANL, Argonne, Ilinois, 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
Very short Touschek lifetime becomes a common issue for next-generation ultra-low emittance storage ring light sources. In order to reach a longer beam lifetime, such a machine often requires operating with a vertical-to-horizontal emittance ratio close to an unity, i.e. a ‘‘round beam''. In tests at the APS storage ring, we determined how a round beam can be reached experimentally. Some general issues, such as beam injection, optics measurement and corrections, and orbit correction have been tested also. To demonstrate that a round beam was achieved, the beam size ratio is calibrated using beam lifetime measurement.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMA013

Export •

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

TUPJE064

Calibration of Fast Fiber-Optic Beam Loss Monitors for the Advanced Photon Source Storage Ring Superconducting Undulators

1780

J.C. Dooling, K.C. Harkay, Y. Ivanyushenkov, V. Sajaev, A. Xiao
ANL, Argonne, Ilinois, USA
A. Vella
University of Illinois at Urbana-Champaign, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under contract number DE-AC02-06CH11357.
We report on the calibration and use of fast fiber-optic (FO) beam loss monitors (BLMs) in the Advanced Photon Source storage ring (SR). A superconducting undulator prototype (SCU0) has been operating in SR Sector 6 since the beginning of CY2013, and another undulator SCU1 (a 1.1-m length undulator that is three times the length of SCU0) is scheduled for installation in Sector 1 in 2015. The SCU0 main coil often quenches during beam dumps. MARS simulations have shown that relatively small beam loss (<1 nC) can lead to temperature excursions sufficient to cause quenching when the SCU0 windings are near critical current. To characterize local beam losses, high-purity fused-silica FO cables were installed in Sector 6 next to the SCU0 cryostat and in Sector 1 where SCU1 will be installed. These BLMs aid in the search for operating modes that protect the SCU structures from beam-loss-induced quenching. In this paper, we describe the BLM calibration process that included deliberate beam dumps at locations of BLMs. We also compare beam dump events where SCU0 did and did not quench.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPJE064

Export •

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

TUPJE069

Fast Injection System R&D for the APS Upgrade

1797

F. Lenkszus, J. Carwardine, A.R. Cours, G. Decker, L.H. Morrison, X. Sun, J. Wang, F. Westferro, A. Xiao, C. Yao
ANL, Argonne, Ilinois, USA
A. Krasnykh
SLAC, Menlo Park, California, USA

Funding: Results in this report are derived from work performed at Argonne National Laboratory. Argonne is operated by UChicago Argonne, LLC, for the U.S. Department of Energy under contract DE-AC02-06CH11357.
The MBA upgrade for the APS will operate with bunch swap out and on axis injection. The planned 324 bunch fill pattern places difficult demands on the injection and extraction kickers. The present concept uses dual stripline kickers driven by high Voltage pulsers. Minimizing perturbation on adjacent bunches requires very fast rise and fall times with relatively narrow ~20 nsec, 15 kV pulses. To achieve these requirements we have initiated a multifaceted R&D program. The R&D includes the HV pulser, stripline kicker and HV feedthrough. We have purchased a commercial dual channel HV pulser and are evaluating its performance and reliability. In addition, we are investigating the feasibility of using nonlinear ferrite loaded coaxial cables (shockwave transmission line) to sharpen the leading and trailing edges of high voltage pulses. We are also developing a prototype kicker and high voltage feedthrough. The requirements for injection and extraction, progress on prototype development and results of our HV pulser investigations will be reported.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPJE069

Export •

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

TUPJE075

Simulation Study of Injection Performance for the Advanced Photon Source Upgrade

1816

A. Xiao, V. Sajaev
ANL, Argonne, Ilinois, 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 vertical on-axis injection scheme has been proposed for the hybrid seven-bend-achromat (H7BA) Advanced Photon Source upgrade (APSU) lattice. In order to evaluate the injection performance, various errors, such as injection beam jitter, optical mismatch and errors, and injection element errors have been investigated and their significance has been discovered. Injection efficiency is then simulated under different error levels. Based on these simulation results, specifications and an error-budget for individual systems have been defined.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPJE075

Export •

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

WEPTY014

Development of Fast Kickers for the APS MBA Upgrade

3286

C. Yao, J. Carwardine, A.R. Cours, F. Lenkszus, R.R. Lindberg, L.H. Morrison, X. Sun, J. Wang, F. Westferro, A. Xiao
ANL, Argonne, Ilinois, USA

Funding: *Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
The APS multi-bend achromat (MBA) upgrade storage ring will support two bunch fill patterns: a 48-singlets and a 324-singlets. A “swap out” injection scheme is adopted. In order to minimize the beam loss and residual oscillation of injected beam and to minimize the perturbation of stored beam during a swap-on injection, the rise, fall, and flat-top parts of the kicker pulse must be held within a 22.8-ns interval. Traditional ferrite-core-type kickers can’t meet the timing requirements; therefore, we decided to use stripline-type kickers. We have completed a preliminary design of a prototype kicker geometry. Procurement of the pulser supply and other components of an evaluation system is under way. We report the specification and design of the fast kicker and current status.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY014

Export •

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