PAC2013 - List of Authors (Yao, C.)

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.

WEPSM13	On-axis Injection Scheme for Ultra-Low-Emittance Light Sources	1076
	A. Xiao, M. Borland, C. Yao ANL, Argonne, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357. An ultra-low-emittance light source generally manifests very strong non-linear effects due to the significant focusing force applied and the resultant strong sextupoles. As one of the consequences, the dynamic aperture becomes very small, and only on-axis "swap-out" beam injection is workable. Another consequence is that the intra-beam scattering (IBS) effect and beam instability are much more severe, which limits the maximum achievable single-bunch intensity. As a result, multiple bunches with tight bunch spacing are required to reach high average beam current, which requires injection to be finished in a very short period, e.g., during the interval between bunches. Using a multi-bend-achromat (MBA) lattice designed for the Advanced Photon Source (APS) storage ring as an example, this paper presents an on-axis injection scheme based on the fast stripline technique together with discussions on how the scheme works with different parameter settings.

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.

WEPSM13

On-axis Injection Scheme for Ultra-Low-Emittance Light Sources

1076

A. Xiao, M. Borland, C. Yao
ANL, Argonne, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
An ultra-low-emittance light source generally manifests very strong non-linear effects due to the significant focusing force applied and the resultant strong sextupoles. As one of the consequences, the dynamic aperture becomes very small, and only on-axis "swap-out" beam injection is workable. Another consequence is that the intra-beam scattering (IBS) effect and beam instability are much more severe, which limits the maximum achievable single-bunch intensity. As a result, multiple bunches with tight bunch spacing are required to reach high average beam current, which requires injection to be finished in a very short period, e.g., during the interval between bunches. Using a multi-bend-achromat (MBA) lattice designed for the Advanced Photon Source (APS) storage ring as an example, this paper presents an on-axis injection scheme based on the fast stripline technique together with discussions on how the scheme works with different parameter settings.