Author: Farvacque, L.
Paper Title Page
WEPC13 Optimisation of the SVD Treatment in the Fast Orbit Correction of the ESRF Storage Ring 694
  • E. Plouviez, F. Epaud, L. Farvacque, J.M. Koch
    ESRF, Grenoble, France
  The ESRF fast orbit correction system has been in operation since May 2012. The orbit correction scheme relies classically on the calculation of a correction orbit based on the SVD analysis of the response matrix of our 224 BPMs to each of our 96 correctors. The rate of the calculation of the corrections is 10 KHz; we use a PI loop achieving a bandwidth of 150Hz completed with a narrow band pass filter with extra gain at 50Hz. In order to make the best use of the correctors dynamic range and of the resolution of the calculation, it can be useful to limit the bandwidth of loop for the highest order vectors of the SVD, or even to totally remove some of these vectors from the correction down to DC. Removing some of the eigen vectors while avoiding that the loop becomes unstable usually increases a lot the complexity of the matrix calculations: we have developed an algorithm which overcomes this problem; The test of this algorithm is presented. We present also the beneficial effect at high frequency of the limitation of the gain of the correction of the highest SVD eigen vectors on the demand of the peak strength of the correctors and on the resolution of the correction calculation.  
poster icon Poster WEPC13 [0.974 MB]  
WEPF11 Emittance Measurement Using X-Ray Lenses at the ESRF 833
  • F. Ewald, J.C. Biasci, L. Farvacque, K.B. Scheidt
    ESRF, Grenoble, France
  During the year 2011, X-ray lenses were tested as an alternative way of emittance measurement in the ESRF storage ring. Following these tests it was decided to install a new bending magnet diagnostics beam port dedicated primarily to a permanent emittance measurement using X-ray lens imaging. The new beam port is equipped with a thin (0.6 mm) double CVD diamond window instead of 3 mm aluminium used at the pinhole beam ports. This increases the X-ray transmission, especially at low energies. The imaging and emittance measurement using aluminium lenses is discussed in comparison to the emittance measurement based on pinhole imaging. Although the principle works correctly, the setup presents different practical difficulties, such as low signal intensity and heat load.