CTF3

Paper	Title	Other Keywords	Page
MOPLS059	The Probe Beam Linac in CTF3	linac, CLIC, gun, emittance	679
	A. Mosnier, M. Authier, D. Bogard, A. Curtoni, O. Delferriere, G. Dispau, R. Duperrier, W. Farabolini, P. Girardot, M. Jablonka, J.L. Jannin, M. Luong, F. Peauger CEA, Gif-sur-Yvette N. Rouvière IPN, Orsay R. Roux LAL, Orsay
	The test facility CTF3, presently under construction at CERN within an international collaboration, is aimed at demonstrating the key feasibility issues of the multi-TeV linear collider CLIC. The objective of the probe beam linac is to "mimic" the main beam of CLIC in order to measure precisely the performances of the 30 GHz CLIC accelerating structures. In order to meet the required parameters of this 200 MeV probe beam, in terms of emittance, energy spread and bunch-length, the most advanced techniques have been considered: laser triggered photo-injector, velocity bunching, beam-loading compensation, RF pulse compression … The final layout is described, and the selection criteria and the beam dynamics results are reviewed.
MOPLS090	Design of a Strip-line Extraction Kicker for CTF3 Combiner Ring	kicker, impedance, simulation, power-supply	762
	I. Rodriguez, F. Toral CIEMAT, Madrid L. García-Tabarés CEDEX, Madrid A. Ghigo, F. Marcellini INFN/LNF, Frascati (Roma)
	The new CLIC test facility (CTF3) is the latest stage to prove the technical feasibility of the CLIC project. An extraction kicker is necessary for the combiner ring, and it will be a strip-line type device due to lower coupling impedances and straightforward fabrication. The field uniformity together with a correct beam dynamics are the most challenging issues of this design. The main parameters of the kicker are analytically calculated using standard analytic formulae. The numeric modelling and simulation of several possible straight sections are reported, and the characteristic impedance is matched with the 50 Ω load. The field homogeneity, the kick angle and the scattering parameters are calculated in a 3D finite element model. Several manufacturing issues for the first prototype are also outlined.
MOPLS093	Commissioning Status of the CTF3 Delay Loop	CLIC, linac, CERN, wiggler	771
	R. Corsini, S. Doebert, F. Tecker, P. Urschütz CERN, Geneva D. Alesini, C. Biscari, B. Buonomo, A. Ghigo, F. Marcellini, B. Preger, M. Serio, A. Stella INFN/LNF, Frascati (Roma)
	The CLIC Test Facility CTF3, built at CERN by an international collaboration, aims at demonstrating the feasibility of the CLIC scheme by 2010. In particular, one of the main goals is to study the generation of high-current electron pulses by interleaving bunch trains in delay lines and rings using transverse RF deflectors. This will be done in the 42 m long delay loop, built under the responsibility of INFN/LNF, and in the 84 m long combiner ring that will be installed in 2006. The delay loop installation was completed, and its commissioning started at the end of 2005. In this paper the commissioning results are presented, including the first tests of beam recombination.
MOPLS097	Progress on the CTF3 Test Beam Line	CLIC, lattice, quadrupole, extraction	783
	D. Schulte, S. Doebert, G. Rumolo, I. Syratchev CERN, Geneva D. Carrillo CIEMAT, Madrid
	In CLIC, the RF power to accelerate the main beam is produced by decelerating a drive beam. The test beamline (TBL) of the CLIC test facility (CTF3) is designed to study and validate the stability of the drive beam during deceleration. This is one of the R&D items required from the International Linear Collider Technical Review Committee to demonstrate feasibility of CLIC. It will produce 30 GHz rf power in the GW range and allow to benchmark computer codes used for the CLIC decelerator design. Different options of this experimental beam line are discussed.
MOPLS101	Beam Dynamics and First Operation of the Sub-harmonic Bunching System in the CTF3 Injector	simulation, CERN, bunching, linac	795
	P. Urschütz, H.-H. Braun, G. Carron, R. Corsini, S. Doebert, T. Lefevre, G. McMonagle, J. Mourier, J.P.H. Sladen, F. Tecker, L. Thorndahl, C.P. Welsch CERN, Geneva
	The CLIC Test Facility CTF3, built at CERN by an international collaboration, aims at demonstrating the feasibility of the CLIC scheme by 2010. The CTF3 drive beam generation scheme relies on the use of a fast phase switch of a sub-harmonic bunching system in order to phase-code the bunches. The amount of charge in unwanted satellite bunches is an important quantity, which must be minimized. Beam dynamics simulations have been used to study the problem, showing the limitation of the present CTF3 design and the gain of potential upgrades. In this paper the results are discussed and compared with beam measurements taken during the first operation of the system.
MOPLS102	Beam Dynamic Studies and Emittance Optimization in the CTF3 Linac at CERN	emittance, linac, quadrupole, simulation	798
	P. Urschütz, H.-H. Braun, R. Corsini, S. Doebert, F. Tecker CERN, Geneva A. Ferrari UU/ISV, Uppsala
	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 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 different modes of operation suggest rms emittances well below the nominal (100 pi mm mrad) and a convincing agreement with PARMELA simulations.
MOPLS103	A High-gradient Test of a 30 GHz Molybdenum-iris Structure	CLIC, electron, vacuum, diagnostics	801
	W. Wuensch, C. Achard, H.-H. Braun, G. Carron, R. Corsini, S. Doebert, R. Fandos, A. Grudiev, E. Jensen, T. Ramsvik, J.A. Rodriguez, J.P.H. Sladen, I. Syratchev, M. Taborelli, F. Tecker, P. Urschütz, I. Wilson CERN, Geneva H. Aksakal Ankara University, Faculty of Sciences, Tandogan/Ankara Ö.M. Mete Ankara University, Faculty of Engineering, Tandogan, Ankara
	The CLIC study is investigating a number of different materials as part of an effort to find ways to increase achievable accelerating gradient. So far, a series of rf tests have been made with a set of identical-geometry structures: a tungsten-iris 30 GHz structure, a molybdenum-iris 30 GHz structure and a scaled molybdenum-iris X-band structure. A second molybdenum-iris 30 GHz structure of the same geometry has now been tested in CTF3 with pulse lengths up to 350 ns. The new results are presented and compared to those of the previous structures to determine dependencies of quantities such as accelerating gradient, material, frequency, pulse length, power flow, conditioning rate and breakdown rate.
MOPLS129	Integration of the PHIN RF Gun into the CLIC Test Facility	emittance, gun, CERN, bunching	861
	S. Doebert CERN, Geneva
	CERN is a collaborator within the European PHIN project, a joint research activity for Photo injectors within the CARE program. The scope of this project is to build an RF Gun equipped with high quantum efficiency Cs2Te cathodes and a laser to produce the nominal beam for the CLIC Test Facility (CTF3). The nominal beam for CTF3 has an average current of 3.5 A, 1.5 GHz bunch repetition frequency and a pulse length of 1.5 us (2310 bunches) with quite tight stability requirements. In addition a phase shift of 90 deg is needed after each train of 140 ns for the special CLIC combination scheme. This RF Gun will be tested at CERN in fall 2006 and should be integrated as a new injector into the CTF3 linac, replacing the existing injector consisting of a thermionic gun and a subharmonic bunching system. The paper studies the optimal integration into the machine trying to optimize transverse and longitudinal phase space of the beam while respecting the numerous constraints of the existing accelerator. The presented scheme uses emittance compensation and velocity bunching to fulfill the requirements.
TUPCH082	The EuroTeV Confocal Resonator Monitor Task	coupling, pick-up, vacuum, resonance	1202
	V.G. Ziemann, T. J. C. Ekelof, A. Ferrari, M. A. Johnson, E. A. Ojefors, A. B. Rydberg UU/ISV, Uppsala F. Caspers CERN, Geneva
	We describe the progress in the analysis of the confocal resonator monitor task which is part of the diagnostics workpackage of EuroTeV. The initial design was analyzed both numerically and experimentally and found limitations. We therefore digressed from strict confocality and report the numerical analysis and S-parameter measurements of a modified design. Furthermore, we discuss the mechanical design needed for planned tests with beam in CTF3 which requires integration of the monitor into the beam pipe, damping of trapped modes, and frequency tunability.
TUPCH086	Precision Beam Timing Measurement System for CLIC Synchronization	CLIC, linac, pick-up, CERN	1211
	J.P.H. Sladen, A. Andersson CERN, Geneva
	Very precise synchronization between main and drive beams is required in CLIC to avoid excessive luminosity loss due to energy variations. One possibility to accomplish this would be to measure and correct the drive beam phase. The timing reference for the correction could be the beam in the transfer line between the injector complex and the main linac. The timing of both main and drive beams will have to be measured to a precision in the region of 10 fs. The aim is to achieve this by means of a beam measurement at 30 GHz with the signal mixed down to an intermediate frequency (IF) for precise phase detection. The RF and IF electronics are being developed and tests will be carried out in CTF3.
TUPCH088	High Dynamic Range Beam Profile Measurements	beam-losses, CLIC, injection, site	1217
	C.P. Welsch, E. Bravin, B. Burel, T. Lefevre CERN, Geneva T. Chapman, M.J. Pilon Thermo, Liverpool, New York
	In future high intensity, high energy accelerators, beam loss has to be minimized to maximize performance and minimize activation of accelerator components. It is imperative to have a clear understanding of the mechanisms that can lead to halo formation and to have the possibility to test available theoretical models with an adequate experimental setup. Measurements based on optical transition radiation (OTR) provide an interesting opportunity for high resolution measurements of the transverse beam profile. In order to be applicable for measurements within the beam halo region, it is of utmost importance that a high dynamic range is covered by the image acquisition system. The existing camera system as it is installed in the CLIC Test Facility (CTF3) is compared to a step-by-step measurement with a photo multiplier tube (PMT) and measurements with a cooled charge injection device (CID) camera. The latter acquisition technique provides an innovative and highly flexible approach to high dynamic range measurements and is presented in some detail.
TUPCH089	Investigations of OTR Screen Surfaces and Shapes	radiation, focusing, diagnostics, electron	1220
	C.P. Welsch, E. Bravin, T. Lefevre CERN, Geneva
	Optical transition radiation (OTR) has proven to be a flexible and effective tool for measuring a wide range of beam parameters, in particular the beam divergence and the transverse beam profile. It is today an established and widely used diagnostic method providing linear real-time measurements. Measurements in the CLIC Test Facility (CTF3) showed that the performance of the present profile monitors is limited by the optical acceptance of the imaging system. In this paper, two methods to improve the systems' performance are presented and results from measurements are shown. First, the influence of the surface quality of the OTR screen itself is addressed. Several possible screen materials have been tested to which different surface treatment techniques were applied. Results from the measured optical characteristics are given. Second, a parabolic-shaped screen support was investigated with the aim of providing an initial focusing of the emitted radiation and thus to reduce the problem of aperture limitation. Measured and calculated emission distributions are presented.
TUPCH142	Development of a Novel RF Waveguide Vacuum Valve	vacuum, CLIC, coupling, electromagnetic-fields	1349
	A. Grudiev CERN, Geneva
	The development of a novel rf waveguide vacuum valve is presented. The rf design is based on the use of TE0n modes of circular waveguides. In the device, the T·1001 mode at the input is converted into a mixture of several TE0n modes which provide low-loss rf power transmission across the vacuum valve gap, these modes are then converted back into the T·1001 mode at the output. There are a number of advantages associated with the absence of surface fields in the region of the valve: 1)Possibility to use commercially available vacuum valves equipped with two specially designed mode converter sections. 2)No necessity for an rf contact between these two sections. 3)Increased potential for high power rf transmission. This technology can be used for all frequencies for which vacuum waveguides are used. The only drawback is that, in rectangular waveguides, mode converters from the operating mode into the T·1001 mode and back again are necessary. Experimental results for the 30 GHz valves developed for the CLIC Test Facility 3 (CTF3) are presented showing in particular that the rf power transmission losses are below 1%.
TUPCH144	Automatic Conditioning of the CTF3 RF System	klystron, vacuum, controls, CERN	1355
	J.P.H. Sladen, S. Deghaye, S. Livesley, J. Marques Balula, J. Mourier, J.-M. Nonglaton CERN, Geneva A. Dubrovsky JINR, Dubna, Moscow Region
	The RF system of CTF3 (CLIC Test Facility 3) includes ten 35 MW to 40 MW 3 GHz klystrons and one 20 MW 1.5 GHz klystron. High power RF conditioning of the waveguide network and cavities connected to each klystron can be extremely time consuming. Because of this, a fully automatic conditioning system has been developed within a CERN JINR (Dubna) collaboration. It involves relatively minor hardware additions, most of the work being in application and front-end software. The system has already been used very successfully.
TUPCH163	Status of 30 GHz High Power RF Pulse Compressor for CTF3	laser, CLIC, vacuum, linac	1405
	I. Syratchev CERN, Geneva
	A 70 ns 30 GHz pulse compressor with resonant delay lines has been built and installed in the CTF3 test area to obtain the high peak power of 150 MW necessary to demonstrate the full performance of the new CLIC accelerating structure. This pulse compressor will be commissioned at high power in 2006. Different methods to provide fast RF phase switching are discussed. The current status of the CTF3 RF pulse compressor commissioning and first results are presented.
WEYPA03	CLIC Feasibility Study in CTF3	CLIC, linac, collider, CERN	1862
	A. Ghigo INFN/LNF, Frascati (Roma)
	After a reminder of the CLIC scheme towards multi-TeV Linear Collider and of the main challenges of this novel technology, the presentation will focus on the CTF3 test facility presently under construction at CERN to address all key issues in a multi-lateral collaboration. It will present the status of the facility and of the technological developments, especially the high field accelerating structures and the RF power production, the performances already achieved as well as the plans and schedule for the future. It will finally compare the CTF3 results with those foreseen by the theory and the corresponding benchmarking of CLIC simulations.
	Transparencies
WEPLS020	The RF Deflector for the CTF3 Delay Loop	klystron, linac, vacuum, coupling	2436
	F. Marcellini, D. Alesini INFN/LNF, Frascati (Roma)
	In the CLIC Test Facility 3 (CTF3) a 42 m long ring, called delay loop, is used to halve the distance between bunches in the drive beam. The compression is obtained by merging two adjacent bunch trains from the linac deflected in opposite directions by an RF device, in such a way that the first train is forced to perform a full revolution in the delay loop, while the second one passes through. The length of the ring is an odd multiple of half the distance between bunches in the beam from the linac. The RF deflector consists of two identical cavities connected to the RF power source through a hybrid junction that equally splits the power and isolates the klystron from reflections. Its innovative design, the results of electromagnetic simulations and expected performances are described, together with low level RF measurements for test and characterization of the device before installation. Preliminary recombination results with the CTF3 beam are also shown. The RF deflector has also been used to measure the length of the accelerated bunches.
WEPLS023	The Two-beam Test-stand in CTF3	CLIC, diagnostics, linac, dipole	2445
	V.G. Ziemann, T. J. C. Ekelof, M. A. Johnson UU/ISV, Uppsala H.-H. Braun, S. Doebert, G. Geschonke, J.P.H. Sladen, W. Wuensch CERN, Geneva
	The acceleration concept for CLIC, based on the two-beam acceleration scheme, where the 30 GHz RF power needed to accelerate the high energy beam is generated by a high-intensity but rather low energy drive beam, will be tested in the two-beam test-stand in CTF3. There RF-structures will be tested at full pulse length. The extreme power levels of up to 640 MW warrant a careful diagnostic system to analyze RF breakdown by observing the effect on both probe- and drive-beam but also the RF signals and secondary effects such as emitted light, vibrations, vacuum, temperatures. We describe the experimental setup and the diagnostic system planned to be installed in CTF3 for 2007.
WEPLS059	The PHIN Photoinjector for the CTF3 Drive Beam	gun, laser, CERN, vacuum	2517
	R. Losito, H.-H. Braun, N. Champault, E. Chevallay, V. Fedosseev, A. Kumar, A.M. Masi, G. Suberlucq CERN, Geneva G. Bienvenu, B.M. Mercier, C.P. Prevost, R. Roux LAL, Orsay M. Divall, G.J. Hirst, G. Kurdi, W. E. Martin, I. O. Musgrave, I. N. Ross, E. L. Springate CCLRC/RAL, Chilton, Didcot, Oxon
	A new photoinjector for the CTF3 drive beam has been designed and is now being constructed by a collaboration among LAL, CCLRC and CERN within PHIN, the second Joint Research Activity of CARE. The photoinjector will provide a train of 2332 pulses at 1.5 GHz with a complex timing structure (sub-trains of 212 pulses spaced from one another by 333 ps or 999 ps) to allow the frequency multiplication scheme, which is one of the features of CLIC, to be tested in CTF3. Each pulse of 2.33 nC will be emitted by a Cs2Te photocathode deposited by a co-evaporation process to allow high quantum efficiency in operation (>3% for a minimum of 40 h). The 3 GHz, 2 1/2 cell RF gun has a 2 port coupler to minimize emittance growth due to asymmetric fields, racetrack profile of the irises and two solenoids to keep the emittance at the output below 20 pi.mm.mrad. The laser has to survive very high average powers both within the pulse train (15 kW) and overall (200 W before pulse slicing). Challenging targets are also for amplitude stability (<0.25% rms) and time jitter from pulse to pulse (<1ps rms). An offline test in a dedicated line is foreseen at CERN in 2007.