• W. Farabolini, D. Bogard, A. Curtoni, P. Girardot, F. Peauger, C.S. Simon
  CEA, Gif-sur-Yvette
• E. Chevallay, M. Divall Csatari, N. Lebas, M. Petrarca
  CERN, Geneva
• A. Palaia, R.J.M.Y. Ruber, V.G. Ziemann
  Uppsala University, Uppsala

The probe beam LINAC, CALIFES, of the CLIC Test Facility (CTF3) has been developed by CEA Saclay, LAL Orsay and CERN to deliver trains of short bunches (0.75 ps) spaced by 0.666 ps at an energy around 170 MeV with a charge of 0.6 nC to the TBTS (Two-beam Test Stand) intended to test the high gradient CLIC accelerating structures. Based on 3 former LIL accelerating structures and on a newly developed RF photo-injector, the whole accelerator is powered with a single 3 GHz klystron delivering pulses of 45 MW through a RF pulse compression cavity and a network of waveguides, splitters, phase-shifters and an attenuator. We relate here results collected during the various commissioning and operation periods which led to nominal performances and stable beam characteristics delivered to the TBTS. Progress has been made in the laser system for beam charge and stability, in space charge compensation for emittance, in RF compression law for energy and energy spread. The installation of a specially developed RF power phase shifter for the first accelerating structure used in velocity bunching allows the control of the bunch length.

• F. Peauger, W. Farabolini, P. Girardot
  CEA, Gif-sur-Yvette
• A. Andersson, G. Riddone, A. Samoshkin, A. Solodko
  CERN, Geneva
• R.J.M.Y. Ruber
  Uppsala University, Uppsala
• R. Zennaro
  PSI, Villigen

To achieve high luminosity in CLIC, the accelerating structures must be aligned to an RMS accuracy of 5 μm with respect to the beam trajectory. Position detectors called Wakefield Monitors (WFM) are integrated to the structure for a beam based alignment. This paper describes the requirements of such monitors. The development plan and basic feature of the WFM as well as the accelerating structure working at 12 GHz and 100 MV/m are shortly described. Then we focus on detailed electromagnetic simulations and design of the WFM itself. In particular, time domain computations are performed and an evaluation of the intrinsic resolution is done for two higher order modes at 17 and 24 GHz. The mechanical design of the accelerating structure with WFM is also presented. Precise machining with a tolerance of 2.5 μm and a surface roughness of 0.025 μm is demonstrated. The fabrication status of three complete accelerating structures with WFM is finally presented for a feasibility demonstration with beam in CTF3 at CERN.