03 Technology
3B Room Temperature RF

Paper	Title	Page
SUPB031	The Nonresonant Perturbation Theory Based Field Measurement and Tuning of a Linac Accelerating Structure	80
	W. Fang, Q. Gu, Z.T. Zhao SINAP, Shanghai, People's Republic of China D.C. Tong TUB, Beijing, People's Republic of China
	Assisted by the bead pull technique, the nonresonant perturbation theory is applied for measuring and tuning the field of the linac accelerating structure. The method is capable of making non-touch measurement, amplitude and phase diagnostics, real time mismatch feedback and field tuning. Main considerations on measurement system and of C-band traveling-wave structure are described, the bead pull measurement and the tuning of the C-band traveling-wave linac accelerating structure are presented.
MOPLB08	Normal Conducting Deflecting Cavity Development at the Cockcroft Institute	159
	G. Burt, P.K. Ambattu, A.C. Dexter, C. Lingwood, B.J. Woolley Cockcroft Institute, Lancaster University, Lancaster, United Kingdom S.R. Buckley, P. Goudket, C. Hill, P.A. McIntosh, J.W. McKenzie, A.E. Wheelhouse STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom V.A. Dolgashev SLAC, Menlo Park, California, USA A. Grudiev CERN, Geneva, Switzerland R.M. Jones UMAN, Manchester, United Kingdom
	Funding: This work has been supported by STFC and the EU through FP7 EUCARD. Two normal conducting deflecting structures are currently being developed at the Cockcroft Institute, one as a crab cavity for CLIC and one for bunch slice diagnostics on low energy electron beams for EBTF at Daresbury. Each has its own challenges that need overcome. For CLIC the phase and amplitude tolerances are very stringent and hence beamloading effects and wakefields must be minimised. Significant work has been undertook to understand the effect of the couplers on beamloading and the effect of the couplers on the wakefields. For EBTF the difficulty is avoiding the large beam offset caused by the cavities internal deflecting voltage at the low beam energy. Propotypes for both cavities have been manufactured and results will be presented.
	Slides MOPLB08 [1.572 MB]
MOPLB09	Status of the C-Band RF System for the SPARC-LAB High Brightness Photoinjector	162
	R. Boni, D. Alesini, M. Bellaveglia, G. Di Pirro, M. Ferrario, A. Gallo, B. Spataro INFN/LNF, Frascati (Roma), Italy A. Mostacci, L. Palumbo URLS, Rome, Italy
	The high brightness photoinjector in operation at the SPARC-LAB facility of the INFN-LNF, Italy, consists of a 150 MeV S-band electron accelerator aiming to explore the physics of low emittance high peak current electron beams and the related technology. Velocity bunching techniques, SASE and Seeded FEL experiments have been carried out successfully. To increase the beam energy and improve the performances of the experiments, it was decided to replace one S-band travelling wave accelerating cavity, with two C-band cavities that allow to reach higher energy gain per meter. The new C-band system is in a well advanced development phase and will be in operation early in 2013. The main technical issues of the C-band system and the R&D activities carried out till now are illustrated in detail in this paper.
	Slides MOPLB09 [1.061 MB]
MOPB079	Normal Conducting Deflecting Cavity Development at the Cockcroft Institute	357
	G. Burt, P.K. Ambattu, A.C. Dexter, C. Lingwood, B.J. Woolley Cockcroft Institute, Lancaster University, Lancaster, United Kingdom S.R. Buckley, P. Goudket, C. Hill, P.A. McIntosh, J.W. McKenzie, A.E. Wheelhouse STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom V.A. Dolgashev SLAC, Menlo Park, California, USA A. Grudiev CERN, Geneva, Switzerland R.M. Jones UMAN, Manchester, United Kingdom
	Funding: This work has been supported by STFC and the EU through FP7 EUCARD. Two normal conducting deflecting structures are currently being developed at the Cockcroft Institute, one as a crab cavity for CLIC and one for bunch slice diagnostics on low energy electron beams for EBTF at Daresbury. Each has its own challenges that need overcome. For CLIC the phase and amplitude tolerances are very stringent and hence beamloading effects and wakefields must be minimised. Significant work has been undertook to understand the effect of the couplers on beamloading and the effect of the couplers on the wakefields. For EBTF the difficulty is avoiding the large beam offset caused by the cavities internal deflecting voltage at the low beam energy. Propotypes for both cavities have been manufactured and results will be presented.
MOPB080	Status of the C-Band RF System for the SPARC-LAB High Brightness Photoinjector	360
	R. Boni, D. Alesini, M. Bellaveglia, G. Di Pirro, M. Ferrario, A. Gallo, B. Spataro INFN/LNF, Frascati (Roma), Italy A. Mostacci, L. Palumbo URLS, Rome, Italy
	The high brightness photoinjector in operation at the SPARC-LAB facility of the INFN-LNF, Italy, consists of a 150 MeV S-band electron accelerator aiming to explore the physics of low emittance high peak current electron beams and the related technology. Velocity bunching techniques, SASE and Seeded FEL experiments have been carried out successfully. To increase the beam energy and improve the performances of the experiments, it was decided to replace one S-band travelling wave accelerating cavity, with two C-band cavities that allow to reach higher energy gain per meter. The new C-band system is in a well advanced development phase and will be in operation early in 2013. The main technical issues of the C-band system and the R&D activities carried out till now are illustrated in detail in this paper.
MOPB081	Travelling Wave Accelerating Structures with a Large Phase Advance	363
	V.V. Paramonov RAS/INR, Moscow, Russia
	The electrons acceleration is considered in higher pass bands of TM01 wave for disk loaded waveguide, resulting in the possibility of traveling wave accelerating structures with an operating field phase advance between 180 – 1260 degrees per cell. With an appropriate shape optimization and some additional elements in cells proposed traveling wave structures have small transverse dimensions and high RF efficiency of standing wave operation. Examples of proposed structures together with RF and dispersion properties are presented.
MOPB082	RF Parameters of the TE - Type Deflecting Structure for S-Band Frequency Range	366
	V.V. Paramonov, L.V. Kravchuk RAS/INR, Moscow, Russia K. Flöttmann DESY, Hamburg, Germany
	Funding: in part RBFR N 12-02-0654-a Effective compact deflecting structure* has been proposed for L-band frequency range preferably. RF parameters of this structure considered for S-band frequency range both for traveling and standing wave operation. * -V. Paramonov, L. Kravchuk, INR, S. Korepanov. Effective Standing Wave RF Structure for Particle Beam Deflector. Proc. 2006 Linac Conference, p. 649
MOPB083	Operational experience with the FERMI@Elettra S-band RF System	369
	A. Fabris, P. Delgiusto, F. Gelmetti, M.M. Milloch, A. Milocco, F. Pribaz, C. Serpico, N. Sodomaco, R. Umer, L. Veljak ELETTRA, Basovizza, Italy
	FERMI@Elettra is a single-pass linac-based FEL user-facility covering the wavelength range from 100 nm (12 eV) to 4 nm (310 eV) and is located next to the third generation synchrotron radiation facility Elettra in Trieste, Italy. The machine is presently under commissioning and the first FEL line (FEL-1) will be opened to the users by the end of 2012. The 1.5 GeV linac is based on S-band technology. The S-band system is composed of fifteen 3 GHz 45 MW peak RF power plants powering the gun, eighteen accelerating structures and the RF deflectors. The S-band system has been set into operation in different phases starting from the second half of 2009. This paper provides an overview of the performance of the system, discussing the achieved results, the strategies adopted to assure them and possible upgrade paths to increase the operability and safety margins of the system.
MOPB084	Design of a C-band Disk-loaded Type Accelerating Structure for a Higher Pulse Repetition Rate in the SACLA Accelerator.	372
	T. Sakurai, T. Inagaki, Y. Otake RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan H. Ego JASRI/SPring-8, Hyogo-ken, Japan
	The higher pulse repetition rate of the SACLA accelerator provides a higher rate of X-ray laser pulses to expand ability of user experiments, such as simultaneously providing the laser to several beamlines and reducing a measuring time in the experiment. Therefore, we studied on a C-band accelerating structure for a higher pulse rate above 120 pps than that of the present case of 60 pps. The designed structure adopts a TM01-2π/3 mode disk-loaded type with a quasi-constant gradient . Since higher repetition rate operation is inclined to increase a number of vacuum electrical discharges, it is required to reduce the surface electric field in the structure. We designed an ellipsoidal curvature shape around an iris aperture, which reduces the maximum surface field by 20%. Since the higher repetition rate also increases the heat load of the structure, in simulation, we optimized cooling channels to obtain acceptable frequency detuning. As the results of the design, an accelerating gradient of more than 40 MV/m will be expected, when an input RF power of 80 MW is applied to the structure. In this paper, we report the design of the C-band accelerating structure and its rf properties.
MOPB086	The Nonresonant Perturbation Theory Based Field Measurement and Tuning of a Linac Accelerating Structure	375
	W. Fang, Q. Gu, Z.T. Zhao SINAP, Shanghai, People's Republic of China D.C. Tong TUB, Beijing, People's Republic of China
	Assisted by the bead pull technique, the nonresonant perturbation theory is applied for measuring and tuning the field of the linac accelerating structure. The method is capable of making non-touch measurement, amplitude and phase diagnostics, real time mismatch feedback and field tuning. Main considerations on measurement system and of C-band traveling-wave structure are described, the bead pull measurement and the tuning of the C-band traveling-wave linac accelerating structure are presented.
MOPB087	S-Band Loads for SLAC Linac	378
	A. Krasnykh, F.-J. Decker SLAC, Menlo Park, California, USA R.W. LeClair INTA, Santa Clara, USA
	Funding: Work supported by the U.S. Department of Energy under contract number DE-AC02-76SF00515 and SBIR grant number DE-SC0007661 The S-Band loads on the current SLAC linac RF system were designed, in some cases, 40+ years ago to terminate 2-3 MW peak power into a thin layer of coated Kanthal material as the high power absorber [1]. The technology of the load design was based on a flame-sprayed Kanthal wire method onto a base material. During SLAC linac upgrades, the 24 MW peak klystrons were replaced by 5045 klystrons with 65+ MW peak output power. Additionally, SLED cavities were introduced and as a result, the peak power in the current RF setup has increased up to 240 MW peak. The problem of reliable RF peak power termination and RF load lifetime required a careful study and adequate solution. Results of our studies and three designs of S-Band RF load for the present SLAC RF linac system is discussed. These designs are based on the use of low conductivity materials. [1] “The Stanford Two-Mile Accelerator”, p. 376-381, R. B. Neal, General Editor, 1968, W. A. Benjamin, Inc., NY Amsterdam
MOPB088	Fabrication Tests for IMP 162.5 MHz RFQ	381
	B. Zhang IMP, Lanzhou, People's Republic of China
	The RFQ for one of front ends of C-ADS is designed. The frequency of the RFQ is 162.5 MHz and the energy is 2.1 MeV. The beam intensity is 15 mA and it works at CW mode. Because of low frequency, the four-wing structure is big size. It makes fabrication will take more risks. Therefore, four fabrication testing were planned and done to minimize the technic risks. The description about fabrication and testing results are presented in the paper.
WE2A01	RF Power Production at the Two Beam Test Stand at CERN	738
	I. Syratchev CERN, Geneva, Switzerland
	The generation of short (250 ns) high peak power (135 MW) RF pulses by decelerating the high current (100 A) bunched (12 GHz) drive beam is one of the key components in the CLIC two beam acceleration scheme. Recent tests with drive beam deceleration at CERN's CTF3, using specially developed 1 m long CLIC Power Extraction and Transfer Structure (PETS) operated in re-circulation regime have successfully demonstrated this concept. The results of these tests are presented.
	Slides WE2A01 [2.636 MB]
TH2A03	Design and Construction of the Linac4 Accelerating Structures	778
	F. Gerigk, Y. Cuvet, A. Dallocchio, G. Favre, J.-M. Geisser, L. Gentini, J.-M. Giguet, S.J. Mathot, M. Polini, S. Ramberger, B. Riffaud, C. Rossi, P. Ugena Tirado, M. Vretenar, R. Wegner CERN, Geneva, Switzerland E. Kendjebulatov, Ya.G. Kruchkov, A.G. Tribendis BINP SB RAS, Novosibirsk, Russia M.Y. Naumenko RFNC-VNIITF, Snezhinsk, Chelyabinsk region, Russia
	The Linac4 project at CERN is at an advanced state of construction. Prototypes of the different types of accelerating structures (RFQ, DTL, CCDTL and pi-mode structures) have been built and are presently tested. This paper gives the status of the cavity production and reviews the RF and mechanical design of the various structure types. Furthermore the production and the first test results shall be presented.
	Slides TH2A03 [2.675 MB]