PAC2013 - List of Authors (Yang, B.X.)

Paper	Title	Page
TUPMA03	Creation of High-charge Bunch Trains from the APS Injector for Swap-out Injection	595
	C. Yao, M. Borland, L. Donley, L. Emery, F. Lenkszus, B.X. Yang ANL, Argonne, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357. A multi-bend-achromat (MBA) extreme low-emittance lattice has been proposed for the future APS Upgrade. Due to its small dynamic aperture, the traditional injection scheme must be replaced with bunch train swap-out scheme. Several options were considered for the creation of a high-charge bunch train from the injector, and we selected an option that builds the bunch train in the particle accumulator ring (PAR). This option enables both single-bunch mode, which is necessary to support current APS operation, and bunch-train mode. This report provides a description of the injection process, simulation results, and specifications of injector timing, kicker, and rf subsystems.

TUPMA04	Observation of +1 Bucket Bunch Impurity Growth at the APS Storage Ring	598
	C. Yao, M. Borland, B.X. Yang ANL, Argonne, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357. The APS storage ring has three fill patterns: 24-singlet, hybrid, and 324 singlet. Bunch purity of better than 10^-6 is required for +3 and higher bucket numbers for the first two fill patterns during user operations. A PAR bunch cleaning system is used to clean up the satellite bunches. During top-up user operation, beam charge in satellite bunches grows due to the long lifetime of the low charge satellites. Recent storage ring development, including operating with the bunch-by-bunch feedback system, reduction of chromaticity, and lattice correction, has increased the beam dynamic aperture of the storage ring. We have observed unusual beam charge growth in +1 buckets, which indicates leakage of electrons from the main bunches to the +1 buckets. This report describes the observation and the dependency of leakage on chromaticity settings, and our analysis.

WEPSM14	Advanced X-ray Beam Position Monitor System Design at the APS	1079
	B.X. Yang, G. Decker, J.S. Downey, Y. Jaski, T.L. Kruy, S.-H. Lee, M. Ramanathan, F. Westferro ANL, Argonne, USA
	Funding: Work supported by U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357. As part of the Advanced Photon Source (APS) Upgrade, new x-ray beamline front ends are planned that include extensive integrated x-ray diagnostic capability. The design includes a grazing-incidence insertion device x-ray beam position monitor (GRID-XBPM) based on Cu K-edge x-ray fluorescence from x-rays striking a pair of copper absorbers. At a 1.0-degree grazing incidence angle, the XBPM assembly was designed to withstand two inline Undulator A devices operating at 150-mA beam current, a total power of 16 kW. A second x-ray BPM located outside of the accelerator enclosure monitors back fluorescence from the beamline exit mask, which is a critical beamline-defining aperture. In addition, an intensity monitor is used to detect x-ray flux passing through a front-end mask inside the enclosure, while a second intensity monitor is located immediately downstream of the exit mask. Details of these designs and expected performance will be presented.

THPAC08	Modernization of the Bergoz Multiplexed BPM System for the APS Upgrade	1154
	X. Sun, H. Bui, G. Decker, R.T. Keane, R.M. Lill, B.X. Yang ANL, Argonne, USA
	Funding: * Work supported by U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357 The APS upgrade includes improvements to the Bergoz Multiplexed BPM system, which presently suffers from an aging data acquisition system. The upgrade leverages off the development of an eight-channel data acquisition system featuring modern FPGA flexibility that was designed for the monopulse BPM system. This upgrade also provides an external clock signal synchronized to the APS revolution clock that will eliminate the aliasing caused by the Bergoz asynchronous multiplexing interacting with different accelerator fill patterns. The upgrade will revitalize this system and demonstrate a cost-effective approach to improved beam stability, reliability, and enhanced postmortem capabilities. In this paper we will discuss the upgrade system specifications, design, and prototype test results.

Paper

Title

Page

Creation of High-charge Bunch Trains from the APS Injector for Swap-out Injection

595

C. Yao, M. Borland, L. Donley, L. Emery, F. Lenkszus, B.X. Yang
ANL, Argonne, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
A multi-bend-achromat (MBA) extreme low-emittance lattice has been proposed for the future APS Upgrade. Due to its small dynamic aperture, the traditional injection scheme must be replaced with bunch train swap-out scheme. Several options were considered for the creation of a high-charge bunch train from the injector, and we selected an option that builds the bunch train in the particle accumulator ring (PAR). This option enables both single-bunch mode, which is necessary to support current APS operation, and bunch-train mode. This report provides a description of the injection process, simulation results, and specifications of injector timing, kicker, and rf subsystems.

TUPMA04

Observation of +1 Bucket Bunch Impurity Growth at the APS Storage Ring

598

C. Yao, M. Borland, B.X. Yang
ANL, Argonne, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
The APS storage ring has three fill patterns: 24-singlet, hybrid, and 324 singlet. Bunch purity of better than 10^-6 is required for +3 and higher bucket numbers for the first two fill patterns during user operations. A PAR bunch cleaning system is used to clean up the satellite bunches. During top-up user operation, beam charge in satellite bunches grows due to the long lifetime of the low charge satellites. Recent storage ring development, including operating with the bunch-by-bunch feedback system, reduction of chromaticity, and lattice correction, has increased the beam dynamic aperture of the storage ring. We have observed unusual beam charge growth in +1 buckets, which indicates leakage of electrons from the main bunches to the +1 buckets. This report describes the observation and the dependency of leakage on chromaticity settings, and our analysis.

WEPSM14

Advanced X-ray Beam Position Monitor System Design at the APS

1079

B.X. Yang, G. Decker, J.S. Downey, Y. Jaski, T.L. Kruy, S.-H. Lee, M. Ramanathan, F. Westferro
ANL, Argonne, USA

Funding: Work supported by U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
As part of the Advanced Photon Source (APS) Upgrade, new x-ray beamline front ends are planned that include extensive integrated x-ray diagnostic capability. The design includes a grazing-incidence insertion device x-ray beam position monitor (GRID-XBPM) based on Cu K-edge x-ray fluorescence from x-rays striking a pair of copper absorbers. At a 1.0-degree grazing incidence angle, the XBPM assembly was designed to withstand two inline Undulator A devices operating at 150-mA beam current, a total power of 16 kW. A second x-ray BPM located outside of the accelerator enclosure monitors back fluorescence from the beamline exit mask, which is a critical beamline-defining aperture. In addition, an intensity monitor is used to detect x-ray flux passing through a front-end mask inside the enclosure, while a second intensity monitor is located immediately downstream of the exit mask. Details of these designs and expected performance will be presented.

THPAC08

Modernization of the Bergoz Multiplexed BPM System for the APS Upgrade

1154

X. Sun, H. Bui, G. Decker, R.T. Keane, R.M. Lill, B.X. Yang
ANL, Argonne, USA

Funding: * Work supported by U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357
The APS upgrade includes improvements to the Bergoz Multiplexed BPM system, which presently suffers from an aging data acquisition system. The upgrade leverages off the development of an eight-channel data acquisition system featuring modern FPGA flexibility that was designed for the monopulse BPM system. This upgrade also provides an external clock signal synchronized to the APS revolution clock that will eliminate the aliasing caused by the Bergoz asynchronous multiplexing interacting with different accelerator fill patterns. The upgrade will revitalize this system and demonstrate a cost-effective approach to improved beam stability, reliability, and enhanced postmortem capabilities. In this paper we will discuss the upgrade system specifications, design, and prototype test results.