Keyword: coupling
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MOPG03 Investigation of Transverse Beam Instability Induced by an In-vacuum Undulator at SPEAR3 simulation, operation, vacuum, insertion-device 31
  • K. Tian, J.J. Sebek, J.L. Vargas
    SLAC, Menlo Park, California, USA
  Funding: Work supported by U.S. Department of Energy Contract No. DE-AC02-76SF00515
Vertical beam instabilities have been observed at SPEAR3 when a newly installed in-vacuum undulator (IVUN) is operated at a set of narrow gap settings. The source of the instabilities is believed to be vertically deflecting trapped modes inside the IVUN tank that are excited by the beam. We have used beam-based measurements to characterize the frequencies and strengths of the excited modes using both our bunch-by-bunch feedback system and a spectrum analyzer. Using numerical simulations of our IVUN structure, we have found modes with high shunt impedance near the measured frequencies. Recently, we have successfully measured these IVUN modes during our current downtime. In this paper, we will report on the measurements, simulations, and plans to damp these modes.
DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-MOPG03  
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MOPG07 First Operational Experience with the LHC Diode ORbit and OScillation (DOROS) System detector, electronics, embedded, FPGA 43
  • M. Gąsior, G. Baud, J. Olexa, G. Valentino
    CERN, Geneva, Switzerland
  The LHC started high-energy operation in 2015 with new tertiary collimators, equipped with beam position monitors embedded in their jaws. The required resolution and stability of the beam orbit measurements linked to these BPMs were addressed by the development of a new Diode ORbit and OScillation (DOROS) system. DOROS converts the short BPM electrode pulses into slowly varying signals by compensated diode detectors, whose output signals can be precisely processed and acquired with 24-bit ADCs. This scheme allows a sub-micrometre orbit resolution to be achieved with robust and relatively simple hardware. The DOROS system is also equipped with dedicated channels optimised for processing beam oscillation signals. Data from these channels can be used to perform betatron coupling and beta-beating measurements. The achieved performance of the DOROS system triggered its installation on the beam position monitors located next to the LHC experiments for testing the system as an option of improving the beam orbit measurement in the most important LHC locations. After introducing the DOROS system, its performance is discussed through both, beam and laboratory measurements.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-MOPG07  
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MOPG70 Transverse Beam Profiling and Vertical Emittance Control with a Double-Slit Stellar Interferometer controls, electron, optics, radiation 236
  • W.J. Corbett, X. Huang, J. Wu
    SLAC, Menlo Park, California, USA
  • C.L. Li, W.J. Zhang
    East China University of Science and Technology, Shanghai, People's Republic of China
  • T.M. Mitsuhashi
    KEK, Ibaraki, Japan
  • Y.H. Xu
    DongHua University, Songjiang, People's Republic of China
  • W.J. Zhang
    University of Saskatchewan, Saskatoon, Canada
  Double-slit interferometers are useful tools to measure the transverse the cross-section of relativistic charged particle beams emitting incoherent synchrotron radiation. By rotating the double-slit about the beam propagation axis, the transverse beam profile can be reconstructed including beam tilt at the source. The interferometer can also be used as a sensitive monitor for vertical emittance control. In this paper we outline a simple derivation of the Van Cittert-Zernike theorem, present results for a rotating double-slit measurement and demonstrate application of the interferometer to vertical emittance control using the Robust Conjugate Direction Search (RCDS) optimization algorithm.  
poster icon Poster MOPG70 [1.362 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-MOPG70  
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MOPG75 Single Shot Transversal Profile Monitoring of Ultra Low Charge Relativistic Electron Bunches at REGAE electron, background, photon, detector 257
  • H. Delsim-Hashemi
    DESY, Hamburg, Germany
  Relativistic electron microscopes are increasingly under consideration in dream experiments of observing atomic scale motions as they occur. Compared to ordinary electron microscopes with energies limited to few tens of keV, relativistic electrons reduce strongly the space-charge effects. This enables packing more electrons in shorter bunches and thereby capturing atomic scale ultra-fast dynamics in single shot. A typical relativistic-electron-microscope, based on an RF-gun, can provide experiments with couple of thousands to millions of electrons bunched in a few μm length and a transversal dimension of a fraction of a mm. After scattering from a sample and at the position of detector, electrons are distributed over transversal dimensions typically two orders of magnitude larger. For transversal diagnostics before scattering a cost effective solution is implemented while for diffraction pattern detection objective is single-electron imaging with good signal to noise ratio in single shot. In this contribution the implementations and results at REGAE will be presented.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-MOPG75  
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TUPG07 Commisioning of Beam Position and Phase Monitors for LIPAc pick-up, simulation, vacuum, electronics 326
  • I. Podadera, A. Guirao, D. Jiménez-Rey, L.M. Martínez, J. Mollá, A. Soleto, R. Varela
    CIEMAT, Madrid, Spain
  Funding: Work partially supported by the Spanish Ministry of Science and Innovation under project AIC-A-2011-0654 and FIS2013-40860-R
The LIPAc accelerator will be a 9 MeV, 125 mA CW deuteron accelerator which aims to validate the technology that will be used in the future IFMIF accelerator. Several types of Beam Position Monitors BPMs- are placed in each section of the accelerator to ensure a good beam transport and minimize beam losses. LIPAc is presently under installation and commissioning of the second acceleration stage at 5 MeV. In this stage two types of BPMs are used: four striplines to control the position at the Medium Energy Beam Transport line (MEBT), and three striplines to precisely measure the mean beam energy at the Diagnostics Plate. The seven pickups have been installed and assembled in the beamlines after characterization in a wire test bench, and are presently been commissioned in the facility. In addition, the in-house acquisition system has been fully developed and tested in the wire test bench at CIEMAT. In this contribution, the results of the beam position monitors characterization, the tests carried out during the assembly and the first measurements with the electronics system will be reported.
DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-TUPG07  
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TUPG12 Design for the Diamond Longitudinal Bunch-by-Bunch Feedback Cavity cavity, impedance, resonance, HOM 340
  • A.F.D. Morgan, G. Rehm
    DLS, Oxfordshire, United Kingdom
  In 2017 it is planned to install some additional normal conducting cavities into the Diamond storage ring. In order to deal with the potential higher order modes in these we are designing a longitudinal bunch-by-bunch feedback system. This paper will focus on the design of the overloaded cavity kicker, adapted to the Diamond beam pipe cross section. The design has evolved in order to reduce the strong 3rd harmonic resonance seen on the introduction of the racetrack beam pipe. Through a combination of geometry optimisation and the addition of integrated taper transitions this harmonic has been greatly reduced while also minimising sharp resonances below 15GHz. The major features will be described, as well as the expected performance parameters.  
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DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-TUPG12  
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TUPG46 Improvements to the LHC Schottky Monitors pick-up, cavity, insertion, synchrotron 453
  • M. Wendt, M. Betz, O.R. Jones, T. Lefèvre, T.E. Levens
    CERN, Geneva, Switzerland
  The LHC Schottky monitors have the potential to measure and monitor some important beam parameters, tune, momentum spread, chromaticity and emittance, in a non-invasive way. We present recent upgrade and improvement efforts of the transverse LHC Schottky systems operating at 4.8 GHz. This includes optimization of the slotted waveguide pickups and a re-design of the RF front-end electronics to detect the weak, incoherent Schottky signals in presence of large, coherent beam harmonics.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-TUPG46  
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TUPG82 Preliminary Measurement on Potential Luminescent Coating Material for the ESS Target Imaging Systems target, proton, detector, controls 559
  • C.A. Thomas, M.A. Hartl, Y. Lee, T.J. Shea
    ESS, Lund, Sweden
  • E. Adli, H. Gjersdal, M.R. Jaekel, O. Rohne
    University of Oslo, Oslo, Norway
  • S. Joshi
    University College West, Trollhätan, Sweden
  We present in this paper the preliminary measurements performed on luminescent materials to be investigated and eventually coated on the ESS target wheel, the Proton Beam Window separating the end of the ESS Linac and the entrance of the ESS target area, and the ESS Dump. Among all the properties of the luminescent material required for the target imaging systems, luminescence yield and luminescent lifetime are essential for two reasons. The first one is trivial, since this material is the source for the imaging system and sets its potential performance. The lifetime is not generally of importance, unless the object is moving, or time dependence measurements are to be done. In our case, the target wheel is moving, and measurement of the beam density current may have to be performed at the 10μups scale. Thus luminescence lifetime of the coating material should be known and measured. In this paper, we present the luminescence measurements of the photo-luminescent lifetime of several materials currently under studies to be used eventually for the first beam on target.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-TUPG82  
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WEBL03 Beam Shape Reconstruction Using Synchrotron Radiation Interferometry radiation, synchrotron, synchrotron-radiation, simulation 589
  • L. Torino, U. Iriso
    ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
  Synchrotron Radiation Interferometry (SRI) through a double-aperture system is a well known technique to measure the transverse beam size using visible light. In many machines the beam is tilted in the transverse plane, but the SRI technique only allows to directly measure the size of the projection of the beam shape along the axis connecting the two apertures. A method to fully reconstruct the beam in the transverse plane using SRI has been developed and successfully tested at the ALBA synchrotron light source. This report shows the full beam reconstruction technique and presents the results at ALBA. Moreover, we also discuss how this technique could improve the measurement of very small beam sizes, improving the resolution of standard SRI.  
slides icon Slides WEBL03 [20.443 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-WEBL03  
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WEPG05 Design of Stripline Beam Position Monitors for the ESS MEBT impedance, electronics, quadrupole, simulation 620
  • S. Varnasseri, I. Bustinduy, A. Ortega, I. Rueda, A. Zugazaga
    ESS Bilbao, Zamudio, Spain
  • R.A. Baron, H. Hassanzadegan, A. Jansson, T.J. Shea
    ESS, Lund, Sweden
  There will be overall 8 Beam Position Monitors (BPM) installed in MEBT of ESS. Seven of them will be used for the measurement of beam position, phase and intensity. One BPM will be used for the fast timing characterization of the chopped beam. The design is based on shortened stripline to accommodate the signal level for low velocity proton beam within MEBT read by electronics. Due to mechanical space limits, all the BPMs are embedded inside quadrupoles; which requires special care on the magnetic properties of the materials within BPM sets and in particular the feedthroughs. The prototype electromagnetic and mechanical design is finished and its fabrication is underway. This paper gives an overview of the electromagnetic and mechanical design and related analysis including position signal sensitivity of the BPMs.  
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DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-WEPG05  
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WEPG41 Measurement of Coupling Impedances using a Goubau Line impedance, simulation, resonance, scattering 719
  • F. Stulle, J.F. Bergoz
    BERGOZ Instrumentation, Saint Genis Pouilly, France
  • H.-W. Glock
    HZB, Berlin, Germany
  Longitudinal coupling impedances can be deduced from S-Parameter measurements performed on a Goubau Line. The Goubau Line, also known as single wire line, is a variant of the coaxial wire method. Both setups use a wire for mimicking the particle beam. Coaxial tapers at the wire ends adapt wave impedance to the 50ohm impedance of coaxial cables, sources and receivers. But for guiding the electromagnetic wave, the Goubau Line relies on the realistic boundary conditions imposed by an insulated wire instead of using a coaxial shield. Equations for the deduction of longitudinal coupling impedances are reviewed and applied to Goubau Line measurements. Goubau Line measurements and CST Studio simulations are compared, showing good agreement.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-WEPG41  
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