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MOA3CO04 Operational Experience with Fast Fiber-Optic Beam Loss Monitors for the Advanced Photon Source Storage Ring Superconducting Undulators ion, undulator, operation, kicker 28
  • J.C. Dooling, K.C. Harkay, V. Sajaev, H. Shang
    ANL, Argonne, Illinois, USA
  Funding: Work supported by the U.S. Department of Energy, Office of Science, under contract number DE-AC02-06CH11357.
Fast fiber-optic (FFO) beam loss monitors (BLMs) installed with the first two superconducting undulators (SCUs) in the Advanced Photon Source storage ring have proven to be a useful diagnostic for measuring deposited charge (energy) during rapid beam loss events. The first set of FFOBLMs were installed outside the cryostat of the short SCU, a 0.33-m long device, above and below the beam centerline. The second set are mounted with the first 1.1-m-long SCU within the cryostat, on the outboard and inboard sides of the vacuum chamber. The next 1.1-m-long SCU is scheduled to replace the short SCU later in 2016 and will be fitted with FFOBLMs in a manner similar to original 1.1-m device. The FFOBLMs were employed to set timing and voltage for the abort kicker (AK) system. The AK helps to prevent quenching of the SCUs during beam dumps* by directing the beam away from the SC magnet windings. The AK is triggered by the Machine Protection System (MPS). In cases when the AK fails to prevent quenching, the FFOBLMs show that losses often begin before detection by the MPS.
K. Harkay et al., these proceedings
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MOPOB07 Off-Orbit Ray Tracing Analysis for the APS-Upgrade Storage Ring Vacuum System ion, vacuum, photon, storage-ring 82
  • J.A. Carter, K.C. Harkay, B.K. Stillwell
    ANL, Argonne, Illinois, USA
  Funding: Argonne National Laboratory's work was supported by the U.S. Department of Energy, Office of Science under contract DE-AC02-06CH11357.
A MatLab program has been created to investigate off-orbit ray tracing possibilities for the APS-Upgrade stor-age ring vacuum system design. The goals for the pro-gram include calculating worst case thermal loading conditions and finding minimum shielding heights for photon absorbers. The program computes the deviation possibilities of synchrotron radiation rays emitted along bending magnet paths using discretized local phase space ellipses. The sizes of the ellipses are computed based on multi-bend achromat (MBA) lattice parameters and the limiting aperture size within the future storage ring vacuum system. For absorber height calculations, rays are projected from each point in the discretized ellipse to the locations of downstream absorbers. The absorber heights are mini-mized while protecting downstream components from all possible rays. For heat loads, rays are projected until they hit a vacuum chamber wall. The area and linear power densities are calculated based on a ray's distance trav-elled and striking incidence angle. A set of worse case local heat loads is collected revealing a maximum condi-tion that each vacuum component must be designed to withstand.
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MOPOB63 Impact of Cooldown Procedure and Ambient Magnetic Field on the Quality Factor of State-of-the-Art Nb3Sn Single-Cell ILC Cavities ion, cavity, experiment, factory 215
  • D.L. Hall, M. Ge, J.J. Kaufman, M. Liepe, R.D. Porter
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  Funding: DOE
Single-cell Nb3Sn cavities coated at Cornell University have demonstrated quality factors of 1010 at 16 MV/m and 4.2 K in vertical tests, achieving the performance requirements of contemporary modern accelerator designs. In this paper, we present results demonstrating the impact of the cooldown procedure and ambient magnetic fields on the cavity's ability to achieve these quality factors and accelerating gradients. The impact of the magnetic fields from thermoelectric currents, generated by thermal gradients across the cavity during cooldown, are shown to be equivalent to the impact of magnetic fields trapped from ambient sources. Furthermore, the increase in the residual surface resistance due to trapped magnetic flux, from both ambient sources and thermoelectric currents, is found to be a function of the applied RF magnetic field amplitude. A hypothesis for this observation is given, and conclusions are drawn regarding the demands on the cooldown procedure and ambient magnetic fields necessary to achieve quality factors of 1010 at 4.2 K and 16 MV/m or higher.
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MOPOB81 Deposition of Non-Evaporative Getters R&D Activity for HEPS-TF ion, vacuum, cathode, distributed 238
  • P. He, D.Z. Guo, B. Liu, Y. Ma, Y.C. Yang, L. Zhang
    IHEP, Beijing, People's Republic of China
  Non Evaporable Getter(NEG) coating technology was widely used around the world's ultra-low emittance storage rings. It will provide the distributed pumping which is the obvious solution to solve the conductance limitation of narrow vacuum chamber at small magnet aperture. The HEPS-TF is the R&D project of HEPS (High Energy Photon Source), it will cover all of the key technology for HEPS accelerator system and beamlines. In order to meet the small aperture vacuum chamber distributed pumping requirement, the NEG coating R&D for HEPS vacuum chamber is under the way. Getter films deposited on the inner surface of the chamber would transform the vacuum chamber from an outgassing source into a pump. The coating test bench will be shown here and coating procedure will be presented.  
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WEPOA43 Simulations of High Current Magnetic Horn Striplines at Fermilab ion, simulation, experiment, proton 792
  • T. Sipahi, S. Biedron, S.V. Milton
    CSU, Fort Collins, Colorado, USA
  • J. Hylen, R.M. Zwaska
    Fermilab, Batavia, Illinois, USA
  Both the NuMI (Neutrinos and the Main Injector) beam line, that has been providing intense neutrino beams for several Fermilab experiments (MINOS, MINERVA, NOVA), and the newly proposed LBNF (Long Baseline Neutrino Facility) beam line, which plans to produce the highest power neutrino beam in the world for DUNE (the Deep Underground Neutrino Experiment), need pulsed magnetic horns to focus the mesons that decay to produce the neutrinos. The high-current horn and stripline design has been evolving as NuMI reconfigures for higher beam power and to meet the needs of the future LBNF program. We evaluated the two existing high-current striplines for NuMI and NOvA at Fermilab by producing Electromagnetic simulations of the magnetic horns and the required high-current striplines. In this paper, we present the comparison of these two designs using the ANSYS Electric and ANSYS Maxwell 3D codes with special attention on the critical stress points. These results are being used to support the development of evolving horn stripline designs to handle increased electrical current and higher beam power for NuMI upgrades and for the LBNF experiment.  
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