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feedback

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IT04 Fast Positional Global Feedback for Storage Rings closed-orbit, dipole, power-supply, damping 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
  
 
CT05 Daresbury SRS Positional Feedback Systems dipole, multipole, wiggler, photon 64
 
  • S.L. Smith, S.F. Hill
    CLRC, Daresbury Laboratory, Warrington, UK
  The Daresbury SRS is a second generation synchrotron radiation source which ramps from its injection energy of 600 MeV to 2.0 GeV. Beam orbit feedback systems have been in routine operation on the SRS since 1994 and are now an essential element in delivering stable photon beams to experimental stations. The most recent enhancements to these systems have included the introduction of a ramp servo system to provide the orbit control demanded by the installation of two new narrow gap insertion device and development of the vertical orbit feedback system to cope with an increasing number of photon beamlines. This paper summaries the current status of these systems and briefly discusses proposed developments.  
 
CT09 Luminosity Optimization in DAΦNE luminosity, coupling, diagnostics, synchrotron 82
 
  • F. Sannibale
    INFN-LNF, Laboratori Nazionali di Frascati dell'INFN, Frascati, Italy
  DAΦNE the Frascati F-factory, started the two beams commissioning on March 1998. Since then a relevant amount of experience concerning the techniques and procedures for optimizing the luminosity has been acquired. All the schemes used are strongly based on the use of various diagnostic systems including a dedicated luminosity monitor, orbit measurement, tune monitor, synchrotron light monitor and others. A summary of the used techniques, with accent on the diagnostic aspects, is presented.  
 
PS16 The fast head-tail instability suppression in multibunch mode at VEPP-4M injection, kicker, dipole, impedance 138
 
  • G. Karpov, V. Kiselev, V. Smaluk, N. Zinvich
    BINP, Budker Institute of Nuclear Physics, Novosibirsk, Russia
  In this paper the bunch-by-bunch transverse feedback system for suppression fast head-tail as well as coupled bunch instabilities is described. The experimental results of the feedback affecting on the current threshold are presented. The effects of reactive and resistive feedback on the current threshold are discussed. Two times as large the bunch current than the threshold current was obtained.  
 
PT02 Real-time betatron tune measurement in the accelerator ramp at COSY-Jülich betatron, synchrotron, acceleration, diagnostics 156
 
  • J. Dietrich, I. Mohos
    IKP, Forschungszentrum Jülich GmbH, Jülich, Germany
  A new real-time method for betatron tune measurements at COSY was developed and tested from the early 1997. A bandlimited broadband noise source was used for beam excitation, the transversal beam position oscillation was bunch-synchronous sampled and digitized with a high resolution ADC. The Fourier transform of the acquired data represents immediately the betatron tune. After the first promising experiments an automatic tunemeter was constructed. The tunemeter is used as routine diagnostic tool since end of 1998.  
 
PT05 First results on closed-loop tune control in the CERN-SPS quadrupole, simulation, acceleration, controls 165
 
  • L. Jensen, O.R. Jones, H. Schmickler
    CERN, Geneva, Switzerland
  This paper presents the first measurements performed with the SPS Qloop. The emphasis will be laid on the model used for designing the regulation loop and how well it fits reality.  
 
PT06 New digital BPM system for the Swiss light source storage-ring, closed-orbit, booster, alignment 168
 
  • M. Dehler, A. Jaggi, P. Pollet, T. Schilcher, V. Schlott, R. Uršič, R. deMonte
    PSI, Paul Scherrer Institut, Villigen, Switzerland
  This paper presents a new digital beam position monitor (DBPM) system which is currently under development for the Swiss Light Source (SLS). It is designed to provide sub-micron position data in normal closed orbit, and feedback mode as well as turn by turn information for machine studies and real time tune measurements. The self calibrating four channel system consists of a RF front end, a digital receiver and a DSP module. The same electronics will be used in all sections of the SLS accelerator complex. The system can be reconfigured in real time to perform different kind of measurements like: pulsed for linac and transfer lines, first turn, turn-by-turn, closed orbit, feedback and even tune mode for booster and storage ring. These reconfigurations only involve downloading of new signal processing software and will be performed via EPICS control system. An independent system for monitoring mechanical drifts of the BPM stations will be installed as well. The measured data will be permanently updated in a database and taken into account, when processing the final electron beam positions.