Author: Farabolini, W.
Paper Title Page
MOPAB107 A Method for Determining the Roll Angle of the CLIC Accelerating Structures From the Beam Shape Downstream of the Structure 368
 
  • J. Ögren, V.G. Ziemann
    Uppsala University, Uppsala, Sweden
  • W. Farabolini
    CEA/DSM/IRFU, France
 
  The Compact Linear Collider (CLIC) accelerating structures have a four-fold symmetry from the radial waveguides for damping higher order modes. This symmetry allows for an octupole component of the rf fields to co-propagate with the main accelerating field. The effect of this octupole mode has been observed at the CLIC test facility 3. In CLIC the accelerating structures are mounted together on a moveable girders. There are four vertical and four horizontal actuators on the girder, which allows for 5D control in a limited range and for instance we can roll the girder. By observing the beam shape perturbed by the octupole field on a screen downstream from the structure we can determine the roll angle and thus align the structure azimuthally. Here we discuss a possible method and show some preliminary results.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB107  
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MOPAB108 Beam-Based Alignment Studies at CTF3 Using the Octupole Component of CLIC Accelerating Structures 371
 
  • J. Ögren, A.K. Bhattacharyya, M. Holz, R.J.M.Y. Ruber, V.G. Ziemann
    Uppsala University, Uppsala, Sweden
  • W. Farabolini
    CEA/DSM/IRFU, France
 
  The Compact Linear Collider (CLIC) uses normal-conducting accelerating structures that are sensitive to wakefield effects and therefore their alignment is extremely important. Due to the four-fold symmetry of the structures, they allow for an octupole component of the rf fields. By scanning the beam transversely we can determine the center of the structures from the shifts in beam position due to the kicks from the octupole field. We present some initial results from measurements at the CLIC test facility 3 at CERN.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB108  
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