H. Shaker, Institute for research in fundamental science, Iran; CERN, Switzerland E. Adli, University of Oslo, Norway; CERN, Switzerland R. Corsini, A. Dabrowski, A. Latina, T. Lefevre, P. K. Skowronski, F. Tecker, P. Urschutz, CERN, Switzerland Abstract The aim of the CLIC Test Facility CTF3, built at CERN by an international collaboration, is to address the main feasibility issues of the CLIC electron-positron linear collider technology by 2010. One key-issue studied in CTF3 is the generation of the very high current drive beam, used in CLIC as the RF power source. It is particularly important to simulate and control the drive beam longitudinal dynamics in the drive beam generation complex, since it directly affects the efficiency and stability of the RF power production process. In this paper we describe the ongoing effort in modelling the longitudinal evolution of the CTF3 drive beam and compare the simulations with experimental results. Our study is based on single bunch simulation.

The CLIC study is high power testing accelerating structures in a number of different materials and accelerating structure designs to understand the physics of breakdown, determine the appropriate scaling of performance and in particular to find ways to increase achievable accelerating gradient. The most recent 30 GHz structures which have been tested include damped structures in copper, molybdenum, titanium and aluminum. The results from these new structures are presented in this paper.

Small transverse beam emittances and well-known lat- tice functions are crucial for the 30 GHz power production in the Power Extraction and Transfer Structure (PETS) and for the commissioning of the Delay Loop of the CLIC Test Facility 3 (CTF3). Following beam dynamics simulation results, two additional solenoids were installed in the CTF3 injector in order to improve the emittance. During the runs in 2005 and 2006, an intensive measurement campaign to determine Twiss parameters and beam sizes was launched. The results obtained by means of quadrupole scans for dif- ferent modes of operation suggest emittances well below the nominal ǫn,rms = 100 π� m and a good agreement with PARMELA simulations.

Small transverse beam emittances and well-known lattice functions are crucial for the 30 GHz power production in the Power Extraction and Transfer Structure (PETS) and for the commissioning of the Delay Loop of the CLIC Test Facility 3 (CTF3). Following beam dynamics simulation results, two additional solenoids were installed in the CTF 3 injector in order to improve the emittance. During the runs in 2005 and 2006, an intensive measurement campaign to determine Twiss parameters and beam sizes was launched. The results obtained by means of quadrupole scans for different modes of operation suggest emittances well below the nominalǫn,rms = 100πμm and a good agreement with PARMELA simulations.

An efficient RF to beam energy transfer in the accelerat- ing structures of the drive beam is one of the key points of the Compact Linear Collider (CLIC) RF power source. For this, the structures are fully beam-loaded, i.e. the acceler- ating gradient is nearly zero at the downstream end of each structure. In this way, about 96 % of the RF energy can be transferred to the beam. To demonstrate this mode of oper- ation, 1.5 μs long beam pulses are accelerated in six fully loaded structures in the CLIC Test Facility (CTF3) Linac. The final beam energy is compared to the input RF power of the structures, proving the efficient energy transfer.

An efficient RF to beam energy transfer in the accelerating structures of the drive beam is one of the key points of the Compact Linear Collider (CLIC) RF power source. For this, the structures are fully beam-loaded, i.e. the accelerating gradient is nearly zero at the downstream end of each structure. In this way, about 96 % of the RF energy can be transferred to the beam. To demonstrate this mode of operation, 1.5 s long beam pulses are accelerated in six fully loaded structures in the CLIC Test Facility (CTF3) Linac. The final beam energy is compared to the input RF power of the structures, proving the efficient energy transfer. Presented at LINAC06, Knoxville, TN, US, August 21-25, 2006 Geneva, Switzerland November 2006 C E R N -O PE N -2 00 607 0