Author: Fukami, K.
Paper Title Page
MOPRO081 Resonance Frequency Feedback System for a Precise Magnet Alignment using Multi-vibrating Wires 277
 
  • K. Fukami, N. Azumi, T. Fujita, T. Honiden, H. Kimura, T. Nakanishi, Y. Okayasu, C. Zhang
    JASRI/SPring-8, Hyogo-ken, Japan
  • K. Kajimoto, T. Watanabe
    SES, Hyogo-pref., Japan
  • S. Matsui
    RIKEN/SPring-8, Hyogo, Japan
 
  An ultimate storage ring (USR) is being designed at synchrotron radiation facilities in the world. USR can generate theoretically minimum synchrotron radiation because emittance of the USR is less than diffraction limit of the radiation. The USR requires high alignment precision of micro-meter order. A vibrating wire method (VWM) has widely been used for such a high precision alignment. An error field of multi-pole magnet is estimated by detecting a vibration of a single wire excited with AC current. The wire position, where no vibration is excited, is defined as the magnetic center. The applied frequency is kept on a resonant frequency, which may drift due to temperature change etc. during the measurement. To trace the resonant frequency at all times, we developed a frequency feedback system. It is necessary to trace the resonance, even when the wire is set in the vicinity of the magnetic center where the magnetic field is nearly zero. Here we propose to install one or two additional wires parallel to the original wire. The additional wires off the center can detect the vibration frequency with enough S/N ratio. We discuss the effectiveness of it for quick and reliable alignment.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO081  
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MOPRO082 Suppression of Stored Beam Oscillation at Injection by Fast Kicker in the SPring-8 Storage Ring 280
 
  • C. Mitsuda, K. Fukami, K. Kobayashi, M. Masaki, H. Ohkuma, S. Sasaki, K. Soutome
    JASRI/SPring-8, Hyogo-ken, Japan
  • T. Nakanishi
    SES, Hyogo-pref., Japan
 
  When the injection bump orbit is not closed perfectly at the beam injection, the horizontal stored beam oscillation is excited. In the SPring-8 storage ring, many efforts had been paid to reduce the beam oscillation by adjusting the temporal shape and timing of four bump magnets and by applying a counter kick to the residual oscillation, whose amplitude is as large as 0.4mm and the width is as narrow as 500ns. Now, the averaged oscillation amplitude has successfully been suppressed to the level of less than 0.1mm. To confirm the suppression effect, we observed the turn-by-turn photon beam profile at the diagnostics beamline with the insertion device. We confirmed that the light axis oscillation was significantly suppressed by a factor of 5 comparing by applying a counter kick. We also found that the oscillation shape and the oscillation amplitude, which were caused by the timing shift of firing bump magnets, are drastically changed by only timing shift of one magnet. We are considering the feedback scheme to keep the suppression effect at the initial level during the user-time.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO082  
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MOPRO083 Design Study of High Brilliant Optics at the SPring-8 Storage Ring 283
 
  • Y. Shimosaki, T. Aoki, K. Fukami, K.K. Kaneki, K. Kobayashi, M. Masaki, C. Mitsuda, H. Ohkuma, M. Shoji, K. Soutome, S. Takano, M. Takao
    JASRI/SPring-8, Hyogo-ken, Japan
 
  At the SPring-8 storage ring, design study of beam optics concentrating particularly on increasing brilliance, not flux density, is in progress besides continuous efforts of increasing both brilliance and flux density for the user optics. The natural emittances are theoretically reduced from 2.41 nmrad at 8 GeV to 2.27 nmrad (8 GeV), 1.78 nmrad (7 GeV) and 1.33 nmrad (6 GeV) by utilizing an emittance damping effect by the insertion devices. The designed optics has experimentally been examined at 6 GeV, and the electron beam parameters have been confirmed by measurements at the diagnostics beamlines.
* Y. Shimosaki et al., “New Optics with Emittance Reduction at the SPring-8 Storage Ring”, IPAC13, MOPEA027.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO083  
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TUPRO092 Magnetic-field Variable Permanent Dipole Magnet for Future Light Sources 1253
 
  • T. Watanabe, K. Fukami, T. Nakanishi, S. Sasaki
    JASRI/SPring-8, Hyogo, Japan
 
  Permanent dipole magnets with variable magnetic field have been designed, fabricated, and tested at SPring-8. Permanent magnets can be advantageous over electromagnets in terms of reliability, stability and compactness in addition to the small power consumption. No unexpected down of an accelerator due to power supply failure is supposed to happen. There is no cooling water flow that can induce a fluctuation of the magnetic field. These features may become important for future light sources, where a very reliable, stable, and compact ring is required. In addition, the power consumption is now one of the most important issues after the 3.11 disaster in Japan. One of critical issues to realize such a magnet is that a magnetic field has to be tuned. In the future, combined-functioned and longitudinally gradient magnets will play a key role in achieving extremely small emittance. In such a case, changing a gap will not work any more. We have designed and fabricated a permanent dipole magnet of which magnetic field can be tuned without changing the gap. The results of the performance test will be presented and a possibility to apply it for future light sources will be discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRO092  
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