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| TUPMN107 | A Proposed Multipole Wiggler for CAMD | 1161 |
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| It is proposed to replace the 7 Tesla wavelength shifter, which has been operating in CAMD since 1998, with a superconducting Multi Pole Wiggler (MPW). This will have 11 main poles with peak fields of 7.5 Tesla and will be accommodated in a cryo-cooled cryostat whose overall length will be 2.5 m. It will be necessary to modify the storage ring lattice parameters in order to inject into the reduced 20 mm vertical aperture of this MPW. The results are presented of tests which have been made of several different lattice configurations which have low vertical beta at the proposed location of the MPW. | ||
| THPAN095 | Implementation and Performance of Parallelized Elegant | 3444 |
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Funding: Work supported by the U. S. Department of Energy, Office of Science, Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The program Elegant* is widely used for design and modeling of linacs for free-electron lasers and energy recovery linacs, as well as storage rings and other applications. As part of a multi-year effort, we have parallelized many aspects of the code, including single-particle dynamics, wakefields, and coherent synchrotron radiation. We report on the approach used for gradual parallelization, which proved very beneficial in getting parallel features into the hands of users quickly. We also report details of parallelization of collective effects. Finally, we discuss performance of the parallelized code in various applications.
*M. Borland, APS Light Source Note LS-287, September 2000. |
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| THPAN099 | Direct Space-Charge Calculation in Elegant and Its Application to the ILC Damping Ring | 3456 |
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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. |
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| FRPMN103 | Single-Bunch Instability Estimates for the 1-nm APS Storage Ring Upgrade with a Smaller Vacuum Chamber | 4330 |
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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. |
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| FRPMN104 | Impedance Database II for the Advanced Photon Source Storage Ring | 4336 |
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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 first Impedance Database* constructed at the Advanced Photon Source was successfully used in reproducing the main characteristics of single-bunch instabilities observed in the storage ring. However, the finite bandwidth of the corresponding impedance model was limited to 25 GHz, which happens to be the resolution limit of the density modulation observed in the microwave instability simulation. In order to resolve simulation results never verified in the experiments, we decided to extend the calculated bandwidth of impedance to 50 GHz by recalculating the wake potentials excited by a shorter bunch. Since low-order electromagnetic code requires 20-40 grid points per wavelength, reducing the bunch length required a large number of grids for the 3D structure. We used bunch lengths of 1- and 2-mm in the Gaussian distribution in the Impedance Database II project. For the large-scale computation we used the 3D electromagnetic code GdfidL ** for wake potential calculation at the cluster equipped with 240 GB of memory. The resultant wake potential excited by the short bunch together with application to the storage ring for collective effects is presented in the paper.
* Y.-C. Chae, "The Impedance Database and Its Application to the APS Storage Ring" Proc. 2003 PAC, p. 3017.** http://www.gdfidl.de |