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damping

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IT04 Fast Positional Global Feedback for Storage Rings feedback, closed-orbit, dipole, power-supply 7
 
  • E. Plouviez
    ESRF, The European Synchrotron Radiation Facility, Grenoble, France
  Stability of the closed orbit of a storage ring is limited by the stability of the components defining this orbit: magnets position and field values. Measurements of the variation of the stored beam orbit with respect to a nominal orbit and application of orbit correction derived from these measurements can reduce these distortions. The subject of this talk is the implementation of such correction at high frequencies (up to about 100 Hz) using global correction schemes. The basic theoretical aspects of the problem will be presented:
  • Global versus local scheme
  • Feedback loop dynamics.
The technical problems associated with the implementation of such systems will also be addressed:
  • BPM and correctors design
  • Feedback loop electronic design
  
 
PS07 Trajectory Measurements in the DAΦNE Transfer Lines linac, pick-up, injection, vacuum 115
 
  • A. Stella, C. Milardi, M. Serio
    INFN-LNL, Laboratori Nazionali di Legnaro, Legnaro, Italy
  An improved beam position monitor system has been installed in the Transfer Lines (TL) connecting the DAΦNE Linac to the collider Main Rings through the Damping Ring, to monitor the beam trajectory and optimize the transmission efficiency. Signals from stripline type beam position monitors are stretched, sampled through Track & Hold circuits and digitized to 12 bits. The sampling stage is triggered, according to the timing of the desired beam, to measure the amplitude of the signals induced on a BPM. Hardware control, data collection and reconstruction of the beam position along the Transfer Lines are performed by the DAΦNE Control System on a VME standard local processor. Design issues, implementation and performance of the system are presented.  
 
PT11 Dipole modes study by means of HOM couplers at SBTF kicker, dipole, coupling, pick-up 183
 
  • N. Baboi, M. Dohlus, A. Jöstingmeier, N. Holtkamp, M. Wendt, M. Nagl, J. Boster, H. Hartwig
    DESY, Deutsches Elektronen Synchrotron, Hamburg, Germany
  High order modes (HOM) are generated by the interaction of a bunched beam with an accelerator environment. They may act destructively on following particle bunches, leading to an increase of the transverse oscillation amplitude and finally to the deterioration of the emittance. Dipole modes have been studied at the S-Band Test Facility at DESY. One accelerating structure, specially designed for this test linac, is equipped with waveguide pick-ups for measuring the HOMs. For one part of the experiments, a modulation of the transverse offset of the bunches at the structure entrance has been induced using a fast broadband kicker and the effect was measured with a precise stripline BPM. No high impedance modes were clearly found in the structure, which has been detuned and damped by both the tapered geometry of the structure and an absorbing stainless steel coating applied on the iris tips.