TUP2WD —  WG-D   (06-Mar-18   16:00—18:00)
Chair: Y.B. Leng, SINAP, Shanghai, People's Republic of China
Paper Title Page
Next Generation X-Ray Beam Position Monitor Development for the Advanced Photon Source Upgrade  
  • B.X. Yang
    ANL, Argonne, Illinois, USA
  Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
Current undulator XBPMs in the Advanced Photon Source (APS) can handle limited beam power and have strong bend magnet background. The next generation XBPM will separate the power-handling elements from the signal detectors using x-ray fluorescence from aperture components and x-ray scattering from low-Z blades. They showed distinct design advantages: (1) The water-cooled aperture components greatly enhance power-handling capacity, up to the APS-U 20-kW undulators. (2) Additional x-ray optics, such as pinhole-camera, enables center-of-mass, gap-independent measurements. (3) Proper beam-intercepting elements tailor the XBPM spectral properties and suppress the background, improving undulator measurement accuracy. (4) Using limiting apertures as the XBPM allows aiming the undulator beam reliably at the aperture during user operations, eliminating the common alignment issue between the aperture and the XBPM. In this report, we discuss the x-ray physics, mechanical design, computer simulation and beam measurements of these x-ray beam position monitors for the APS Upgrade. Possible applications to the free electron laser will be discussed.
slides icon Slides TUP2WD01 [5.383 MB]  
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Emittance Measurements on Future Ring Light Sources  
  • Å. Andersson
    MAX IV Laboratory, Lund University, Lund, Sweden
  The MAX IV 3 GeV ring is designed to produce a bare lattice horizontal electron beam emittance of 330 pm·rad. We present different methods using visible or near visible SR, for measuring this so far unsurpassed low horizontal emittance. In this way we can minimize systematic errors, and we also point out those measurement methods that could best serve emittance determinations on future, below 100 pm·rad, emittance light sources.  
slides icon Slides TUP2WD02 [9.112 MB]  
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TUP2WD03 Turn-by-Turn Measurements for Systematic Investigations of the Micro-Bunching Instability 46
  • J.L. Steinmann, M. Brosi, E. Bründermann, M. Caselle, S. Funkner, B. Kehrer, A.-S. Müller, M.J. Nasse, G. Niehues, L. Rota, M. Schuh, P. Schönfeldt, M. Siegel, M. Weber
    KIT, Karlsruhe, Germany
  Funding: Funded by the German Federal Ministry of Education and Research (Grant No. 05K16VKA) & Initiative and Networking Fund of the Helmholtz Association (contract number: VH-NG-320).
While recent diffraction-limited storage rings provide bunches with transverse dimensions smaller than the wavelength of the observed synchrotron radiation, the bunch compression in the longitudinal plane is still challenging. The benefit would be single cycle pulses of coherent radiation with many orders of magnitude higher intensity. However, the self-interaction of a short electron bunch with its emitted coherent radiation can lead to micro-bunching instabilities. This effect limits the bunch compression in storage rings currently to the picosecond range. In that range, the bunches emit coherent THz radiation corresponding to their bunch length. In this paper, new measurement setups developed at the Karlsruhe Institute of Technology are described for systematic turn-by-turn investigations of the micro-bunching instability. They lead to a better understanding thereof and enable appropriate observation methods in future efforts of controlling and mastering the instability. Furthermore, the described setups might also be used as high repetition rate bunch compression monitors for bunches of picosecond length and below.
slides icon Slides TUP2WD03 [8.524 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-TUP2WD03  
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TUP2WD04 Preliminary Design of HEPS Storge Ring Vacuum Chambers and Components 52
  • P. He, B. Deng, D.Z. Guo, Q. Li, B.Q. Liu, Y. Ma, Y.C. Yang, L. Zhang
    IHEP, Beijing, People's Republic of China
  • X.J. Wang
    Institute of High Energy Physics (IHEP), People's Republic of China
  In the design process of HEPS vacuum system, we meet the following limitations. Vacuum chamber must fit inside multipole magnet bore diameter of 25mm (without touching). Water channels and x-ray extraction ports must pass through a 11mm vertical pole gap. Provide an average pressure of 1nTorr during operations with 200mA beam current. Control thermal drift of BPM to ~μm and vibration amplitude ~nm level. Minimize impedance effects. This paper introduces the design of various vacuum chambers, including material selection, mechanical simulation analysis, welding test and so on.  
slides icon Slides TUP2WD04 [4.062 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-TUP2WD04  
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