A   B   C   D   E   F   G   I   J   K   L   N   P   R   S   T    

ESRF

Paper Title Other Keywords Page
IT08 Breaking New Ground with High Resolution Turn-By-Turn BPMs at the ESRF instrumentation, diagnostics, pick-up 36
 
  • L. Farvacque, R. Nagaoka, K. Scheidt
    ESRF, Grenoble, France
  This High-Resolution, Turn-by-Turn BPM system is a low-cost extension to the existing BPM system, based on the RF-multiplexing concept, used for slow Closed-Orbit measurements. With this extension Beam Position measurements in both planes, at all (224) BPMs in the 844 m ESRF Storage Ring, for up to 2048 Orbit Turns with 1 μm resolution are performed. The data acquisition is synchronised to a single, flat 1 μs, transverse deflection kick to the 1μs beamfill in the 2.8μs revolution period. The high quality of this synchronisation, together with the good reproducibility of the deflection kick and the overall stability of the Closed Orbit beam allows to repeat the kick and acquisition in many cycles. The subsequent averaging of the data obtained in these cycles yields the 1um resolution. The latter allows lattice measurements with high precision such as the localisation of very small focussing errors and modulation in Beta values and phase advances. It also finds an unique application to measure, model, and correct the (H to V) Betratron coupling which recently showed successfully the reduction of coupling and vertical emittance below respectively 0.3% and 12picometer×rad. This method takes full benefit from 64 BPM stations situated around 32 straight-sections (no focussing elements) of 6m length allowing the phase-space measurements in their centers.  
 
CT09 X-Ray Interference Methods of Electron Beam Diagnostics instrumentation, diagnostics, emittance, synchrotron-radiation 88
 
  • O. Chubar, A. Snigirev, S. Kuznetsov, T. Weitkamp
    ESRF, Grenoble, France
  • V. Kohn
    RRC, Russian Research Center 'Kurchatov Institute', Moscow
  Electron beam diagnostics methods based interference and diffraction of synchrotron radiation (SR) in hard X-ray range will be discussed. Two simple optical schemes providing X-ray interference patterns highly sensitive to transverse size of the emitting electron beam, will be considered. For each scheme, the visibility of fringes in the pattern depends on transverse size of the electron beam. However, the pattern is also determined by the scheme geometry, shape and material of diffracting bodies. Therefore, for correct interpretation of the experimental results, high-accuracy computation of SR emission and propagation in the framework of physical optics should be used. Examples of practical measurements and processing of the results are presented.  
 
PS14 Microwave Pickups for the Observation of Multi GHz Signals Induced by the ESRF Storage Ring Electron Bunches instrumentation, diagnostics, pick-up, storage-ring, emittance 136
 
  • E. Plouviez
    ESRF, European Synchrotron Radiation Facility, Grenoble, France
  The length of the bunches stored in ESRF lies in the 30 ps to 120 ps range (FWHM). The observation of single bunch phenomena like transverse or longitudinal oscillations or bunch length variation requires the acquisition and analysis of signals at frequencies higher than 10 GHz. A set of microwave cavity pick ups operating at 10 GHz and 16 GHz together with the appropriate electronics has been implemented on the ESRF storage ring; it detects the wall currents on the vacuum chamber due to the electron beams circulation. We describe the design of these cavities, give the result and analysis of measurements performed with the pick ups and indicate how we plan to use these devices as beam diagnostics  
 
PM20 A High Dynamic Range Bunch Purity Tool instrumentation, diagnostics, synchrotron-radiation, emittance 216
 
  • B. Joly, G.A. Naylor
    ESRF, Grenoble, France
  The European synchrotron radiation facility uses a stored electron beam in order to produce x-rays for the study of matter. Some experiments make use of the time structure of the x-ray beam which is a direct reflection of the time structure in the electron beam itself. Avalanche photo-diodes have been used in an x-ray beam in a photon counting arrangement to measure the purity of single or few bunch filling modes. Conventional techniques measuring the photon arrival times with a time to analogue converter (TAC) achieve dynamic ranges in the 10-6 range. We report here the use of a gated high count rate device achieving a measurement capability of 10-10. Such high purity filling modes are required in synchrotron light sources producing x-ray pulses for experiments looking at very weak decay signals as seen in M”ssbauer experiments..  
 
PM21 DSP and FPGA Based Bunch Current Signal Processing instrumentation, diagnostics, closed-orbit, controls, simulation 219
 
  • G.A. Naylor
    ESRF, Grenoble, France
  The current in electron storage rings used as synchrotron light sources must be measured to a very high precision in order to determine the stored beam lifetime. This is especially so in high-energy machines in which the lifetime may be very high. Parametric current transformers (PCT) have traditionally been used to measure the DC or average current in the machine, which offer a very high resolution. Unfortunately these do not allow the different components of a complex filling pattern to be measured separately. A hybrid filling mode delivered at the ESRF consists of one third of the ring filled with bunches with a single highly populated bunch in the middle of the two-thirds gap. The lifetime of these two components may be very different. Similarly the two components are injected separately and can be monitored separately using a fast current transformer (FCT) or an integrating current transformer (ICT). The signals from these devices can be analysed using high speed analogue to digital converters operating at up to 100MHz and digital signal processing (DSP) techniques involving the use of field programmable gate arrays (FPGAs) in order to process the continuous data stream from the converters.