• H. Shaker
  IPM, Tehran
• R. Corsini, H. Shaker, P.K. Skowronski, I. Syratchev, F. Tecker
  CERN, Geneva

The pulse compressor is located after the klystron to increase the power peak by storing the energy at the beginning and releasing it near the end of klystron output pulse. In the CTF3 [1] pulse compressors a doubling of the peak power is achieved according to our needs and the machine parameters. The magnitude of peak power, pulse length and flatness can be controlled by using a phase modulator for the input signal of klystrons. A C++ code is written to simulate the pulse compressor behaviour according to the klystron output pulse power. By manually changing the related parameters in the code for the best match, the quality factor and the filling time of pulse compressor cavities can be determined. This code also calculates and sends the suitable phase to the phase modulator according to the klystron output pulse power and the desired pulse length and peak power.

• F. Marcellini, D. Alesini, A. Ghigo
  INFN/LNF, Frascati (Roma)
• A. Andersson, I. Syratchev
  CERN, Geneva

In the two beam acceleration scheme the Main Beam must be precisely synchronized with respect to the RF power produced by the Drive Beam. Timing errors would have an impact on the collider performances. The Drive Beam phase errors should be controlled, by means of a feed forward system, within 0.1° (23fs @ 12GHz) to avoid a luminosity reduction larger than 2%. A beam phase arrival monitor is an essential component of the system. Its design has been based on the following main requirements: resolution of the order of 20fs, very low coupling impedance due to the very high beam current and integrated filtering elements to reject RF noise and weak fields in the beam pipe that could otherwise affect the measurements.

• I. Syratchev, A. Cappelletti
  CERN, Geneva

One crucial development for CLIC is an adjustable high-power rf device which controls the output power level of individual Power Extraction and Transfer Structures (PETS) even while fed with a constant drive beam current. The CLIC two-beam rf system is designed to have a low, approximately 10^-7, breakdown rate during normal operation and breakdowns will occur in both accelerating structures and the PETS themselves. In order to recover from the breakdowns and reestablish stable operation, it is necessary to have the capability to switch off a single PETS/accelerating structure unit and then gradually ramp generated power up again. The baseline strategy and implementation of such a variable high-power mechanism is described.

• E. Adli
  University of Oslo, Oslo
• A.E. Dabrowski, S. Döbert, M. Olvegård, D. Schulte, I. Syratchev
  CERN, Geneva
• R.L. Lillestol
  NTNU, Trondheim

The CLIC Test Facility 3 Test Beam Line is the first prototype for the CLIC drive beam decelerator. Stable transport of the drive beam under deceleration is a mandatory component in the CLIC two-beam scheme. In the Test Beam Line more than 50% of the total energy will be extracted from a 150 MeV, 28 A electron drive beam, by the use of 16 Power Extraction and Transfer structures. A number of experiments are foreseen to investigate the drive beam characteristics under deceleration in the Test Beam Line, including beam stability, beam blow up and the efficiency of the power extraction. General benchmarking of decelerator simulation and theory studies will also be performed. Specially designed instrumentation including precision BPMs, loss monitors and a time-resolved spectrometer dump will be used for the experiments. This paper describes the experimental program foreseen for the Test Beam Line, including the relevance of the results for the CLIC decelerator studies.

• D. Schulte, R. Corsini, B. Dalena, J.-P. Delahaye, S. Döbert, G. Geschonke, A. Grudiev, J.B. Jeanneret, E. Jensen, P. Lebrun, Y. Papaphilippou, L. Rinolfi, G. Rumolo, H. Schmickler, F. Stulle, I. Syratchev, R. Tomás, W. Wuensch
  CERN, Geneva
• E. Adli
  University of Oslo, Oslo

The physics experiments at CLIC will require that the machine scans lower than nominal centre-of-mass energy. We present different options to achieve this and discuss the implications for luminosity and the machine design.

• F. Toral, P. Abramian, J. Calero, D. Carrillo, F.M. De Aragon, L. García-Tabarés, J.L. Gutiérrez, A. Lara, E. Rodríguez García, L. Sanchez
  CIEMAT, Madrid
• S. Döbert, I. Syratchev
  CERN, Geneva

The goal of the present CLIC test facility (CTF3) is to demonstrate the technical feasibility of the CLIC scheme. The Test Beam Line (TBL) is used to study a CLIC decelerator focusing on 12 GHz power production and the stability of the decelerated beam. The extracted CTF3 drive beam from the combiner ring (CR) features a maximum intensity of 28 A and 140 ns pulse duration, where the Test Beam Line consists of 16 cells, each one including a BPM, a quadrupole on top of a micrometer-accuracy mover and a RF power extractor so-called PETS (Power Extraction and Transfer Structure). This paper describes the first prototype fabrication techniques, with particular attention to the production of the long copper rods which induce the RF generation. A special test bench for the characterization of the device with low RF power measurements has been developed. Performed mesurements of the scattering parameters and the electric field profile along the structure are carefully described. Finally, the prototype has been installed at CLEX, and first measurements with beam are also reported.

• K.M. Schirm, S. Curt, S. Döbert, G. McMonagle, G. Rossat, I. Syratchev, L. Timeo
  CERN, Geneva
• A.A. Haase, A. Jensen, E.N. Jongewaard, C.D. Nantista, D.W. Sprehn, A.E. Vlieks
  SLAC, Menlo Park, California
• A. Hamdi, F. Peauger
  CEA, Gif-sur-Yvette
• S.V. Kuzikov, A.A. Vikharev
  IAP/RAS, Nizhny Novgorod

The CLIC RF frequency has been changed in 2008 from the initial 30 GHz to the European X-band 11.9942 GHz permitting beam independent power production using klystrons for CLIC accelerating structure testing. A design and fabrication contract for five klystrons at that frequency has been signed by different parties with SLAC. France (CEA Saclay) is contributing a solid state modulator purchased in industry to the CLIC study. RF pulses over 120 MW peak at 230 ns length will be obtained by using a novel SLED I type pulse compression scheme designed and fabricated in Nizhny Novgorod, Russia. The X-band power test stand has been installed in the CLIC Test Facility CTF3 for independent structure and component testing in a bunker, but allowing, in a later stage, for powering RF components in the CTF3 beam lines. The design of the facility, results from commissioning of the RF power source and the performance of the Test Facility are reported.