2011 Particle Accelerator Conference - List of Authors (Yao, C.)

Paper	Title	Page
MOP220	The Feasibility of Near-Field ODR Beam-Size Monitoring at 23 GeV at FACET	513
	A.H. Lumpkin Fermilab, Batavia, USA M.J. Hogan SLAC, Menlo Park, California, USA P. Muggli USC, Los Angeles, California, USA C. Yao ANL, Argonne, USA
	Funding: Work partially supported by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy Extension of near-field optical diffraction radiation (ODR) imaging to the 23 GeV beams at the proposed FACET facility at SLAC has been evaluated. The beam- size sensitivity at the 10- to 20- μm σ level based on a simple model will be reported. Polarization effects are also seen to be important and will be discussed. The comparisons to previous experimental results and the modeling results indicate sufficient feasibility for planning of the experiments in the coming year.

TUP190	Upgrade of the APS Booster Synchrotron Magnet Ramp	1181
	C. Yao, B. Deriy, G. Feng, H. Shang, J. Wang ANL, Argonne, USA
	Funding: Work supported by U.S. Department of Energy, Offices of Science, Office of Basic Energy Sciences, under contract No. DE-AC02-06-CH11357 The APS booster is a 7-GeV electron synchrotron with 0.5-second cycle time. Both voltage and current ramp modes were in the original design but only the voltage ramp has been commissioned. Two software-based ramp control programs are used to regulate the current waveform to a linear ramp. The system has been operated for user beam operations for many years. Some instability exists in the ramp correction that requires manual intervention from time to time by the operators. Sensitivity of magnet currents to external changes, such as AC line voltage, harmonic interference from the high-power rf system, etc., has been observed. In order to meet the increased single-bunch-charge requirement of the APS upgrade we need more flexible current ramps such as flat porches for injection and extraction and smooth transitions. Recent efforts to develop an energy-saving operation mode also call for ramp improvement. This paper presents test results of a workstation-based current regulation program and an FPGA-based implementation as a future upgrade.

THP124	Higher Current Operation for the APS Upgrade	2351
	K.C. Harkay, G. Berenc, M. Borland, Y.-C. Chae, L. Emery, D. Horan, R. Nassiri, V. Sajaev, K.M. Schroeder, G.J. Waldschmidt, A. Xiao, C. Yao ANL, Argonne, USA
	Funding: Work supported by U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. The Advanced Photon Source is a 7-GeV hard x-ray synchrotron light source. Operation for users is delivered at a nominal current of 100 mA in one of three bunch patterns. The APS Upgrade calls for a minimum planned operating current of 150 mA, with an option to deliver beam up to 200 mA. The high-current threshold in the storage ring has been explored, and storage ring components have been identified that either drive collective instabilities or are subjected to excessive beam-drive higher-order-mode (HOM) heating. In this paper, we describe machine studies at 150 mA in a special lattice that simulates the upgraded APS. We also describe the accelerator upgrades that are required to accommodate 200-mA operation, as well as the ongoing machine studies plan.

Paper

Title

Page

The Feasibility of Near-Field ODR Beam-Size Monitoring at 23 GeV at FACET

513

A.H. Lumpkin
Fermilab, Batavia, USA
M.J. Hogan
SLAC, Menlo Park, California, USA
P. Muggli
USC, Los Angeles, California, USA
C. Yao
ANL, Argonne, USA

Funding: Work partially supported by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy
Extension of near-field optical diffraction radiation (ODR) imaging to the 23 GeV beams at the proposed FACET facility at SLAC has been evaluated. The beam- size sensitivity at the 10- to 20- μm σ level based on a simple model will be reported. Polarization effects are also seen to be important and will be discussed. The comparisons to previous experimental results and the modeling results indicate sufficient feasibility for planning of the experiments in the coming year.

TUP190

Upgrade of the APS Booster Synchrotron Magnet Ramp

1181

C. Yao, B. Deriy, G. Feng, H. Shang, J. Wang
ANL, Argonne, USA

Funding: Work supported by U.S. Department of Energy, Offices of Science, Office of Basic Energy Sciences, under contract No. DE-AC02-06-CH11357
The APS booster is a 7-GeV electron synchrotron with 0.5-second cycle time. Both voltage and current ramp modes were in the original design but only the voltage ramp has been commissioned. Two software-based ramp control programs are used to regulate the current waveform to a linear ramp. The system has been operated for user beam operations for many years. Some instability exists in the ramp correction that requires manual intervention from time to time by the operators. Sensitivity of magnet currents to external changes, such as AC line voltage, harmonic interference from the high-power rf system, etc., has been observed. In order to meet the increased single-bunch-charge requirement of the APS upgrade we need more flexible current ramps such as flat porches for injection and extraction and smooth transitions. Recent efforts to develop an energy-saving operation mode also call for ramp improvement. This paper presents test results of a workstation-based current regulation program and an FPGA-based implementation as a future upgrade.

THP124

Higher Current Operation for the APS Upgrade

2351

K.C. Harkay, G. Berenc, M. Borland, Y.-C. Chae, L. Emery, D. Horan, R. Nassiri, V. Sajaev, K.M. Schroeder, G.J. Waldschmidt, A. Xiao, C. Yao
ANL, Argonne, USA

Funding: Work supported by U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The Advanced Photon Source is a 7-GeV hard x-ray synchrotron light source. Operation for users is delivered at a nominal current of 100 mA in one of three bunch patterns. The APS Upgrade calls for a minimum planned operating current of 150 mA, with an option to deliver beam up to 200 mA. The high-current threshold in the storage ring has been explored, and storage ring components have been identified that either drive collective instabilities or are subjected to excessive beam-drive higher-order-mode (HOM) heating. In this paper, we describe machine studies at 150 mA in a special lattice that simulates the upgraded APS. We also describe the accelerator upgrades that are required to accommodate 200-mA operation, as well as the ongoing machine studies plan.