• S. Döbert, E. Adli, R.L. Lillestol, M. Olvegård, I. Syratchev
  CERN, Geneva
• D. Carrillo, F. Toral
  CIEMAT, Madrid
• A. Faus-Golfe, J.J. García-Garrigós
  IFIC, Valencia
• Yu.A. Kubyshin
  UPC, Barcelona
• G. Montoro
  EPSC, CASTELLDEFELS

The CLIC Test Facility (CTF3) at CERN was constructed by the CTF3 collaboration to study the feasibility of the concepts for a compact linear collider. The test beam line (TBL) recently added to the CTF3 machine was designed to study the CLIC decelerator beam dynamics and 12 GHz power production. The beam line consists of a F0D0 lattice with high precision BPM's and quadrupoles on movers for precise beam alignment. A total of 16 Power Extraction and Transfer Structures (PETS) will be installed in between the quadrupoles to extract 12 GHz power from the drive beam. The CTF3 drive beam with a bunch-train length of 140 ns, 12 GHz bunch repetition frequency and an average current over the train of up to 28 A will be used. Each PETS structure will produce 135 MW of 12 GHz power at nominal current. The beam will have lost more than 50 % of its initial energy of 150 MeV at the end of the beam line and will contain particles with energies between 67 MeV and 150 MeV. The beam line is completely installed and the PETS structures will be successively added until summer 2011. The paper will describe the first results obtained during commissioning of the beam line and the first PETS prototype.

• S. Döbert, A. Grudiev, G. Riddone, W. Wuensch, R. Zennaro
  CERN, Geneva
• C. Adolphsen, F. Wang, J.W. Wang
  SLAC, Menlo Park, California
• T. Higo, S. Matsumoto, K. Yokoyama
  KEK, Ibaraki

Prototype accelerating structures for the Compact Linear Collider (CLIC) are being developed and high-power tested in a collaboration between SLAC, KEK and CERN. Several undamped, low group-velocity and strongly tapered prototypes (of the so-called T18 design) have been operated above 100 MV/m average gradient at a very low breakdown rates. Recently two new structures with the same iris apertures but now including higher order mode damping waveguides in each cell (TD18 design) have been tested at SLAC and KEK. The damped versions could be processed to similar gradients but an increased breakdown rate was observed. The damping waveguides lead to a magnetic field enhancement in the outer diameter of the cells which results in increased pulsed surface heating. The maximum pulsed temperature rise is 80 deg at the design gradient of 100 MV/m compared to only 20 deg for the undamped version. The high-power tests of the two TD18 structures are analyzed with special emphasis on the influence on breakdown rate of the enhanced magnetic field and consequent increased pulsed surface temperature rise.

• A.E. Dabrowski, E. Adli, S. Bettoni, R. Corsini, S. Döbert, D. Egger, T. Lefèvre, A. Rabiller, P.K. Skowronski, L. Søby, F. Tecker
  CERN, Geneva
• H.-H. Braun
  PSI, Villigen
• H. Shaker
  IPM, Tehran
• M. Velasco
  NU, Evanston

The CLIC Test Facility 3 (CTF3) is being built and commissioned by an international collaboration in order to test the feasibility of the proposed Compact Linear Collider (CLIC) two-beam acceleration scheme. The monitoring and control of the bunch length throughout the CTF3 complex is important since this affects the efficiency and the stability of the RF power production process. Bunch length diagnostics therefore form an essential component of the beam instrumentation at CTF3. This paper presents and compares longitudinal profile measurements based on transverse RF deflectors, Streak camera and non-destructive microwave spectrometry techniques.