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Xiao, A.

Paper Title Page
TUPMN096 New Lattice Design for APS Storage Ring with Potential Tri-fold Increase of the Number of Insertion Devices 1139
 
  • V. Sajaev, M. Borland, A. Xiao
    ANL, Argonne, Illinois
 
  Funding: Work supported by the U. S. Department of Energy, Office of Science, Basic Energy Sciences, under Contract No. DE-AC02-06CH11357

APS has recently held a round of discussions on upgrade options for the APS storage ring. Several options were discussed that included both storage ring and energy-recovery linac options. Here we present a storage ring lattice that fits into the APS tunnel and has a number of significant improvements over the existing storage ring. The present APS lattice has 40-fold symmetry with each sector having one 5-m-long straight section for insertion device (ID) placement. Each sector also provides one beamline for radiation from the bending magnet. The upgrade lattice preserves locations of the existing insertion devices but provides for increased ID straight section length to accommodate 8-m-long insertion devices. This lattice also decreases emittance by a factor of two down to 1.6 nm rad. And last but not least, it provides two additional 2.1-m-long ID straight sections per sector with one of these straight sections being parallel to the existing bending magnet beamline. We also present dynamic aperture optimization, lifetime calculations, and other nonlinear-dynamics-related simulations.

 
THPAN096 A 1-nm Emittance Lattice for the Advanced Photon Source Storage Ring 3447
 
  • A. Xiao, M. Borland, V. Sajaev
    ANL, Argonne, Illinois
 
  Funding: Work supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.

We present a triple-bend lattice design that uses the current APS tunnel. The new lattice has a 1 nm-rad effective emittance at 7 GeV. A forty-period symmetric optics is presented. For the benefit of some X-ray user experiments, an optics with four special straight sections of one-third the beam size of normal sections was investigated as well. The associated nonlinear optical difficulties are addressed and simulation results are presented.

 
THPAN097 International Linear Collider Damping Ring Lattice Design 3450
 
  • A. Xiao, L. Emery
    ANL, Argonne, Illinois
 
  Funding: Work supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.

We present a lattice design based on the theoretical-minimum-emittance (TME) cell for the International Linear Collider (ILC0 6.6-km 5-GeV damping ring. Several areas are discussed: momentum compaction, lattice layout, injection and extraction, circumference adjusters, phase adjuster, and dynamic aperture calculation with multipole errors.

 
THPAN098 Touschek Effect Calculation and Its Application to a Transport Line 3453
 
  • A. Xiao, M. Borland
    ANL, Argonne, Illinois
 
  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 Touschek effect is a major concern for lepton storage rings of low emittance (i.e., high bunch density) and low or moderate beam energy, such as third-generation synchrotron light sources. Piwinski's formula, which includes beam shape variation along the beamline and which is suitable for any beam energy, has been incorporated into a program that interoperates with elegant for use in lifetime calculations. The difference between using Piwinski's method and other simplified methods for the APS is shown in this paper. Furthermore, because of the generality of this formula, we also applied it to transport lines to predict beam loss rates and beam loss locations for the first time. An example related to a possible energy recovery linac upgrade of the APS (APS-ERL) is also given in this paper.

 
THPAN099 Direct Space-Charge Calculation in Elegant and Its Application to the ILC Damping Ring 3456
 
  • A. Xiao, M. Borland, L. Emery, Y. Wang
    ANL, Argonne, Illinois
  • K. Y. Ng
    Fermilab, Batavia, Illinois
 
  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 direct space-charge force model has been implemented in the tracking code elegant. The user can simulate transverse space-charge effects by inserting space-charge elements in the beamline at any desired position. Application to the International Linear Collider damping ring is presented in this paper. We simulated beam under equilibrium conditions, as well as the entire damping cycle from injection to extraction. Results show that beam halo is generated due to space charge effects. This would be a significant concern for the ILC damping ring and a detailed follow-up study is needed.

 
FRPMN103 Single-Bunch Instability Estimates for the 1-nm APS Storage Ring Upgrade with a Smaller Vacuum Chamber 4330
 
  • Y.-C. Chae, Y. Wang, A. Xiao
    ANL, Argonne, Illinois
 
  Funding: Work supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.

We recently studied a lattice achieving 1-nm emittance at the APS storage ring*. The successful design required very strong sextupoles in order to tune the machine to the desired positive chromaticity. A preliminary design of such magnets indicated saturation in the poles unless the vacuum chamber gets smaller by a factor of two compared to the existing APS chamber. Since the resistive wall impedance scales as 1/b3, where b is the radius of the chamber, we questioned how much current we can store in a single bunch at the 1-nm storage ring. In order to answer this question quantitatively, we calculated all wake potentials of impedance elements of the existing APS storage ring with the transverse dimension properly scaled but with the longitudinal dimension kept unchanged. With the newly calculated impedance of a smaller chamber, we estimated the single-bunch current limit. It turned out that the ring with a smaller chamber would not diminish the single-bunch current limit substantially. We present both wake potentials of 1-nm and the existing rings followed by the simulation results carried out for determining the accumulation limit to the ring.

* A. Xiao, "A 1-nm Lattice for the APS Storage Ring" these proceedings.