2011 Particle Accelerator Conference - List of Authors (Xiao, A.)

Paper	Title	Page
WEP063	Tracking Particles Through A General Magnetic Field	1591
	A. Xiao, M. Borland, L. Emery, Y. Wang ANL, Argonne, 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 method that tracks particles directly through a general magnetic field described in a 3D field table was added to the code elegant recently. It was realized by converting an arbitrary particle's motion to a combination of free-drift motion and centripetal motion through the coordinate system rotation and using a general linear interpolation tool developed at the Advanced Photon Source (APS). This method has been tested by tracking particles through conventional magnetic elements (dipole, sextupole, etc.) to verify reference coordinate system conversions, tracking accuracy, and long-term tracking stability. Results show a very good agreement between this new method and the traditional method. This method is not designed to replace mature traditional methods that have been used in most tracking codes. Rather, it is useful for magnets with complicated field profiles or for studying edge effects.

WEP064	Beam Dynamics Study of the Intermediate Energy X-Ray Wiggler for the Advanced Photon Source	1594
	A. Xiao, M. Borland, L. Emery, M.S. Jaski, V. Sajaev ANL, Argonne, 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. An intermediate-energy x-ray (IEX) helical wiggler is planned for the APS storage ring. Because of its high field and rapid field roll-off, the disturbance to the beam dynamics is large and needs to be well understood before the installation. We present a new method of fitting the magnetic field to an analytical wiggler model, which simplifies the usual nonlinear fitting problem and guarantees the best fit. The fitting method was validated by comparison to an analytical method.

THP125	Multi-objective Optimization of a Lattice for Potential Upgrade of the Advanced Photon Source*	2354
	V. Sajaev, M. Borland, L. Emery, A. Xiao ANL, Argonne, 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) is a 7-GeV storage ring light source that has been in operation for over a decade. In the near future, the ring may be upgraded, including changes to the lattice such as provision of several long straight sections (LSSs). Use of deflecting cavities for generation of short x-ray pulses is also considered. Because APS beamlines are nearly fully built out, we have limited freedom to place LSSs in a symmetric fashion. Arbitrarily placed LSSs will drastically reduce the symmetry of the optics and would typically be considered unworkable. We apply a recently developed multi-objective direct optimization technique that relies on particle tracking to compute the dynamic aperture and Touschek lifetime. We show that this technique is able to tune sextupole strengths and select the working point in such a way as to recover the dynamic and momentum acceptances. We also show the results of experimental tests of lattices developed using these techniques.

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

Tracking Particles Through A General Magnetic Field

1591

A. Xiao, M. Borland, L. Emery, Y. Wang
ANL, Argonne, 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 method that tracks particles directly through a general magnetic field described in a 3D field table was added to the code elegant recently. It was realized by converting an arbitrary particle's motion to a combination of free-drift motion and centripetal motion through the coordinate system rotation and using a general linear interpolation tool developed at the Advanced Photon Source (APS). This method has been tested by tracking particles through conventional magnetic elements (dipole, sextupole, etc.) to verify reference coordinate system conversions, tracking accuracy, and long-term tracking stability. Results show a very good agreement between this new method and the traditional method. This method is not designed to replace mature traditional methods that have been used in most tracking codes. Rather, it is useful for magnets with complicated field profiles or for studying edge effects.

WEP064

Beam Dynamics Study of the Intermediate Energy X-Ray Wiggler for the Advanced Photon Source

1594

A. Xiao, M. Borland, L. Emery, M.S. Jaski, V. Sajaev
ANL, Argonne, 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.
An intermediate-energy x-ray (IEX) helical wiggler is planned for the APS storage ring. Because of its high field and rapid field roll-off, the disturbance to the beam dynamics is large and needs to be well understood before the installation. We present a new method of fitting the magnetic field to an analytical wiggler model, which simplifies the usual nonlinear fitting problem and guarantees the best fit. The fitting method was validated by comparison to an analytical method.

THP125

Multi-objective Optimization of a Lattice for Potential Upgrade of the Advanced Photon Source*

2354

V. Sajaev, M. Borland, L. Emery, A. Xiao
ANL, Argonne, 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) is a 7-GeV storage ring light source that has been in operation for over a decade. In the near future, the ring may be upgraded, including changes to the lattice such as provision of several long straight sections (LSSs). Use of deflecting cavities for generation of short x-ray pulses is also considered. Because APS beamlines are nearly fully built out, we have limited freedom to place LSSs in a symmetric fashion. Arbitrarily placed LSSs will drastically reduce the symmetry of the optics and would typically be considered unworkable. We apply a recently developed multi-objective direct optimization technique that relies on particle tracking to compute the dynamic aperture and Touschek lifetime. We show that this technique is able to tune sextupole strengths and select the working point in such a way as to recover the dynamic and momentum acceptances. We also show the results of experimental tests of lattices developed using these techniques.

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.