LINAC2012 - List of Keywords (electron)

Paper	Title	Other Keywords	Page
SUPB009	Linear Accelerator based on Parallel Coupled Accelerating Structure	cavity, controls, focusing, klystron	19
	A.E. Levichev, A.M. Barnyakov, V.M. Pavlov BINP SB RAS, Novosibirsk, Russia Y.D. Chernousov ICKC, Novosibirsk, Russia V. Ivannikov, I.V. Shebolaev ICKC SB RAS, Novosibirsk, Russia
	Accelerating stand based on parallel coupled accelerating structure and electron gun is developed and produced. The structure consists of five accelerating cavities. The RF power feeding of accelerating cavities is provided by common exciting cavity which is performed from rectangular waveguide loaded by reactive pins. Operating frequency is 2450 MHz. Electron gun is made on the basis of RF triode. Linear accelerator was tested with different working regimes. The obtained results are following: energy is up to 4 MeV, accelerating current is up to 300 mA with pulse duration of 2.5 ns on the half of the width; energy is up to 2.5 MeV, accelerating current is up to 100 mA with pulse duration of 5 μs; energy is up to 2.5 MeV, accelerating current is up to 120 mA with pulse duration of 5 μs and beam capture of 100%. The descriptions of the accelerator elements are given in the report. The features of the parallel coupled accelerating structure are discussed. The results of the measuring accelerator’s parameters are presented.

SUPB010	Measurements of a Reduced Energy Spread of a Recirculating Linac by Non-Isochronous Beam Dynamics	recirculation, linac, synchrotron, acceleration	22
	F. Hug, C. Burandt, M. Konrad, N. Pietralla TU Darmstadt, Darmstadt, Germany R. Eichhorn Cornell University, Ithaca, New York, USA
	Funding: supported by DFG through SFB 634 The Superconducting Linear Accelerator S-DALINAC at the University of Darmstadt (Germany) is a recirculating linac with two recirculations providing beams for measurements in nuclear physics at small momentum transfers. For these experiments an energy spread of better than 10^-4 (rms) is needed. Currently acceleration in the linac section is done on crest of the accelerating field. The recirculation path is operated achromatic and isochronous. In this recirculation scheme the energy spread of the resulting beam in the ideal case is determined by the electron bunch length. Taking into account the stability of the RF system the energy spread increases drastically to more than 10^-3 (rms). We will present a new non-isochronous recirculation scheme which helps cancelling out these errors from the rf-control. This scheme uses longitudinal dispersion in the recirculation paths and an acceleration off-crest with a certain phase with respect to the maximum. We will present results of the commissioning of the new system including measurements of the longitudinal dispersion in the recirculation arcs as well as measurements of the resulting energy spread using an electron spectrometer.

SUPB011	Computational Model Analysis for Experimental Observation of Optical Current Noise Suppression Below the Shot-noise Limit	plasma, linac, simulation, beam-transport	25
	A. Nause, A. Gover University of Tel-Aviv, Faculty of Engineering, Tel-Aviv, Israel
	Funding: We acknowledge support of the Israel Science Foundation grant We report first demonstration of optical frequency current shot-noise suppression in a relativistic e-beam. This process is made possible by collective Coulomb interaction between the electrons of a cold intense beam during beam drift, and is essentially a process of longitudinal beam-plasma oscillation [1]. Suppression of beam current noise below the classical “shot-noise” level has been known in the microwave tubes art [2]. This is the first time that it is demonstrated in the optical regime. We predict that the scheme can be extended to the XUV and possibly to shorter wavelengths with further development of technology. The fundamental current shot-noise determines the level of incoherent spontaneous radiation emission from electron-beam optical radiation sources and SASE-FELs [3]. Suppressing shot-noise would make it possible to attain spontaneous emission sub-radiance [4] and surpass the classical coherence limits of seed-injected FELs. The effect was demonstrated by measuring sub-linear growth as a function of current of the OTR Radiation. This finding indicates that the beam charge homogenizes due to the collective interaction, and its distribution becomes sub-Poissonian. [1] A. Gover, E. Dyunin, PRL, 102, 154801, 2009 [2] H. Haus, N. Robinson, Proc. IRE, 43, 981 (1955) [3] P. Emma, et al , Nature Photonics 4, 641 (2010) [4] A. Dicke, Phys. Rev. 93, 99 (1954)

SUPB019	The Multipacting Simulation for the New-Shaped QWR using TRACK3P	cavity, simulation, accelerating-gradient, niobium	50
	C. Zhang, S. He, Y. He, S.C. Huang, Y.L. Huang, T.C. Jiang, R.X. Wang, M.X. Xu, Y.Z. Yang, W.M. Yue, S.H. Zhang, S.X. Zhang, H.W. Zhao IMP, Lanzhou, People's Republic of China
	In order to improve the electro-magnetic performance of the quarter wave resonator, a new-shaped cavity with an elliptical cylinder outer conductor has been proposed. This novel cavity design can provide much lower peak surface magnetic field and much higher Ra/Q0 and G. The Multipacting simulation has been done for this new QWR cavity using ACE3P/TRACK3P code, in this paper the simulation results will be presented and analyzed.

SUPB026	Multipacting Analysis of High-velocity Superconducting Spoke Resonators	cavity, site, simulation, superconductivity	68
	C.S. Hopper, J.R. Delayen ODU, Norfolk, Virginia, USA
	Some of the advantages of superconducting spoke cavities are currently being investigated for the high-velocity regime. When determining a final, optimized geometry, one must consider the possible limiting effects multipacting could have on the cavity. We report on the results of analytical calculations and numerical simulations of multipacting electrons in superconducting spoke cavities and methods for reducing their impact.

SUPB035	RF Photoinjector and Radiating Structure for High-power THz Radiation Source	radiation, coupling, vacuum, impedance	86
	S.M. Polozov, T.V. Bondarenko MEPhI, Moscow, Russia Y.A. Bashmakov LPI, Moscow, Russia
	Sources of high-power electromagnetic radiation in THz band are becoming promising as a new method of a low activation introscopy. Research and development of accelerating RF photoinjector and radiating system for THz radiation source are reported. The photoinjector is based on disk loaded waveguide (DLW). Two different designs of accelerating structures were modeled: widespread 1.6 cell of DLW structure and travelling wave resonator structure. The resonant models of these structures and the structures with power ports were designed. Electrodynamics characteristics and electric field distribution for all models were acquired. Results of picoseconds photoelectron beam dynamics in modeled structures are reported. Design of decelerating structures exciting Cherenkov radiation are based on corrugated metal channel and metal channel coated with dielectric. Analysis of radiation intensity and frequency band are presented.

MO1A02	Status of the European XFEL – Constructing the 17.5 GeV Superconducting Linear Accelerator	cavity, undulator, photon, klystron	105
	W. Decking DESY, Hamburg, Germany
	The European XFEL is presently under construction in Hamburg, Germany. It consists of a 1.2 km long superconducting linac serving an about 3 km long electron beam transport system. Three undulator systems of up to 200 m length each produce hard and soft x-rays via the self-amplified spontaneous emission (SASE) process. We will present the status of the civil construction and the accelerator components. The production of the 100 superconducting accelerator modules is distributed between industries and a collaboration of accelerator laboratories. We describe the carefully orchestrated production sequence, quality assurance measures and risk mitigation mechanisms. The last module is scheduled to be installed in the accelerator in spring 2015 and commissioning with beam will start in summer of that year.
	Slides MO1A02 [8.730 MB]

MOPLB02	Positron Injector Linac Upgrade for SuperKEKB	positron, linac, quadrupole, target	141
	T. Kamitani, M. Akemoto, D.A. Arakawa, Y. Arakida, A. Enomoto, S. Fukuda, K. Furukawa, Y. Higashi, T. Higo, H. Honma, N. Iida, M. Ikeda, E. Kadokura, K. Kakihara, H. Katagiri, M. Kurashina, S. Matsumoto, T. Matsumoto, H. Matsushita, S. Michizono, K. Mikawa, T. Miura, F. Miyahara, T. Mori, H. Nakajima, K. Nakao, T. Natsui, Y. Ogawa, S. Ohsawa, M. Satoh, T. Shidara, A. Shirakawa, H. Sugimoto, T. Suwada, T. Takatomi, T. Takenaka, Y. Yano, K. Yokoyama, M. Yoshida, L. Zang, X. Zhou KEK, Ibaraki, Japan D. Satoh TIT, Tokyo, Japan
	The KEKB B-factory is under an upgrade construction for the SuperKEKB. To achieve 40 times higher luminosity, the linac is required to inject electrons and positrons with higher intensities (e^-: 1 nC → 5 nC, e⁺: 1 nC → 4 nC) and lower emittances (e^-: 300 → 20 μm, e⁺: 2100 → 10 μm). This paper describes the upgrade scheme of the positron source. A new positron capture section will have larger transverse and energy acceptances by introducing a flux concentrator and large aperture L-band and S-band accelerating structures. Beam line layout and quadrupole focusing system will be rearranged for the enlarged beam acceptance. Beam optics is designed to be compatible for positron and electron beams with different energies and emittances. Pulsed quadrupoles and steering magnets are added for better flexibility in optics and orbit tuning. Parameter optimization of the positron source by optics calculation and particle tracking simulation is described.
	Slides MOPLB02 [0.575 MB]

MOPLB03	Advances in Beam Tests of Dielectric Based Accelerating Structures	wakefield, acceleration, laser, linac	144
	A. Kanareykin, S.P. Antipov, J.E. Butler, C.-J. Jing Euclid TechLabs, LLC, Solon, Ohio, USA W. Gai ANL, Argonne, USA V. Yakimenko BNL, Upton, Long Island, New York, USA
	Funding: US Department of Energy Diamond is being evaluated as a dielectric material for dielectric loaded accelerating structures. It has a very low microwave loss tangent, high thermal conductivity, and supports high RF breakdown fields. We report on progress in our recent beam tests of the diamond based accelerating structures of the Ka-band and THz frequency ranges. Wakefield breakdown test of a diamond-loaded accelerating structure has been carried out at the ANL/AWA accelerator. The high charge beam from the AWA linac (~70 nC, σ_z = 2.5 mm) was passed through a rectangular diamond loaded resonator and induce an intense wakefield. A groove is cut on the diamond to enhance the field. Electric fields up to 0.3 GV/m has been detected on the diamond surface to attempt to initiate breakdown. A surface analysis of the diamond has been performed before and after the beam test. Wakefield effects in a 250 GHz planar diamond accelerating structure has been observed at BNL/ATF accelerator as well. We have directly measured the mm-wave wake fields induced by subpicosecond, intense relativistic electron bunches in a diamond loaded accelerating structure via the dielectric wake-field acceleration mechanism.
	Slides MOPLB03 [1.986 MB]

MOPLB04	A 10 MeV L-band Linac for Irradiation Applications in China	linac, gun, klystron, simulation	147
	G. Pei, Y.L. Chi, M.H. Dai, D.Y. He, X. He, X. Li, J. Liu, C. Ma, X. Wang, C.H. Yu, F. Zhao, J. Zhao, Z.S. Zhou IHEP, Beijing, People's Republic of China Y. Feng, H. Huang, S. Shi, E. Tang, X. Yang, Q. Yuan, Z. Zhu Institute of High Energy Physics (IHEP), People's Republic of China Z. Li, X. Zhang Wuxi EL PONT Radiation Technology Ltd, Wuxi, People's Republic of China
	The electron linear accelerator has wide applications, and the demands are keeping growing for the irradiation applications in China. A high beam power 10 MeV L-band Linac has been developed recently as a joint venture of Institute of High Energy Physics and EL-PONT Company. The Thales TH2104U klystron, 3 A thermionic electron gun and three meter L-band disk-loaded constant impedance RF structure are adopted. A stable electron beam of 10 MeV, 40 kW has been obtained in the last May with a microwave to beam efficiency of about 65%. In this paper we will present the detailed design issues and beam commissioning.
	Slides MOPLB04 [1.800 MB]

MOPLB05	Applications of Compact Dielectric-Based Accelerators	coupling, multipactoring, wakefield, impedance	150
	C.-J. Jing, S.P. Antipov, A. Kanareykin, P. Schoessow Euclid TechLabs, LLC, Solon, Ohio, USA M.E. Conde, W. Gai, J.G. Power ANL, Argonne, USA
	Important progress on the development of dielectric based accelerators has been made experimentally and theoretically in the past few years. One advantage of dielectric accelerators over the metallic counterparts is its compact size, which may attract some applications in industrial or medical accelerators. In this article, we discuss the design and technologies of dielectric based accelerators toward these needs.

MOPLB08	Normal Conducting Deflecting Cavity Development at the Cockcroft Institute	cavity, beam-loading, wakefield, damping	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	klystron, coupling, controls, FEL	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]

MOPLB11	The Upgraded Argonne Wakefield Accelerator Facility (AWA): a Test-Bed for the Development of High Gradient Accelerating Structures and Wakefield Measurements	wakefield, gun, linac, acceleration	168
	M.E. Conde, D.S. Doran, W. Gai, R. Konecny, W. Liu, J.G. Power, Z.M. Yusof ANL, Argonne, USA S.P. Antipov, C.-J. Jing Euclid TechLabs, LLC, Solon, Ohio, USA E.E. Wisniewski Illinois Institute of Technology, Chicago, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy under contract No. DE-AC02-06CH11357. Electron beam driven wakefield acceleration is a bona fide path to reach high gradient acceleration of electrons and positrons. With the goal of demonstrating the feasibility of this concept with realistic parameters, well beyond a proof-of-principle scenario, the AWA Facility is currently undergoing a major upgrade that will enable it to achieve accelerating gradients of hundreds of MV/m and energy gains on the order of 100 MeV per structure. A key aspect of the studies and experiments carried out at the AWA facility is the use of relatively short RF pulses (15 – 25 ns), which is believed to mitigate the risk of breakdown and structure damage. The upgraded facility will utilize long trains of high charge electron bunches to drive wakefields in the microwave range of frequencies (8 to 26 GHz), generating RF pulses with GW power levels.
	Slides MOPLB11 [0.900 MB]

MOPLB12	X-Ray Local Energy Spectrum Measurement on Tsinghua Thomson Scattering X-Ray Source (TTX)	scattering, simulation, laser, photon	171
	Y.-C. Du, J.F. Hua, W.-H. Huang, C.-X. Tang, L.X. Yan, H. Zha, Z. Zhang TUB, Beijing, People's Republic of China
	Thomson scattering X-ray source, in which the TW laser pulse is scattered by the relativistic electron beam, can provide ultra short, monochromatic, high flux, tunable polarized hard X-ray pulse which is can widely used in physical, chemical and biological process research, ultra-fast phase contrast imaging, and so on. Since the pulse duration of X-ray is as short as picosecond and the flux in one pulse is high, it is difficult to measure the x-ray spectrum. In this paper, we present the X-ray spectrum measurement experiment on Tsinghua Thomson scattering. The preliminary experimental results shows the maximum X-ray energy is about 47 keV, which is agree well with the simulations.
	Slides MOPLB12 [1.311 MB]

MOPB002	Positron Injector Linac Upgrade for SuperKEKB	positron, linac, quadrupole, target	177
	T. Kamitani, M. Akemoto, D.A. Arakawa, Y. Arakida, A. Enomoto, S. Fukuda, K. Furukawa, Y. Higashi, T. Higo, H. Honma, N. Iida, M. Ikeda, E. Kadokura, K. Kakihara, H. Katagiri, M. Kurashina, S. Matsumoto, T. Matsumoto, H. Matsushita, S. Michizono, K. Mikawa, T. Miura, F. Miyahara, T. Mori, K. Nakao, T. Natsui, Y. Ogawa, S. Ohsawa, T. Shidara, A. Shirakawa, H. Sugimoto, T. Suwada, T. Takatomi, T. Takenaka, Y. Yano, K. Yokoyama, M. Yoshida, L. Zang, X. Zhou KEK, Ibaraki, Japan D. Satoh TIT, Tokyo, Japan
	The KEKB B-factory is under an upgrade construction for the SuperKEKB. To achieve 40 times higher luminosity, the linac is required to inject electrons and positrons with higher intensities (e^-: 1 nC → 5 nC, e⁺: 1 nC → 4 nC) and lower emittances (e^-: 300 → 20 μm, e⁺: 2100 → 10 μm). This paper describes the upgrade scheme of the positron source. A new positron capture section will have larger transverse and energy acceptances by introducing a flux concentrator and large aperture L-band and S-band accelerating structures. Beam line layout and quadrupole focusing system will be rearranged for the enlarged beam acceptance. Beam optics is designed to be compatible for positron and electron beams with different energies and emittances. Pulsed quadrupoles and steering magnets are added for better flexibility in optics and orbit tuning. Parameter optimization of the positron source by optics calculation and particle tracking simulation is described.

MOPB004	Design and Operation of a Compact 1 MeV X-band Linac	cavity, linac, gun, target	183
	G. Burt, T.N. Abram, P.K. Ambattu, C. Lingwood Cockcroft Institute, Lancaster University, Lancaster, United Kingdom I. Burrows, T. Hartnett, J.P. Hindley, C.J. White STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom P.A. Corlett, A.R. Goulden, P.A. McIntosh, K.J. Middleman, Y.M. Saveliev, R.J. Smith STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	A compact 1 MeV linac has been produced at the Cockcroft Institute using X-band RF technology. The linac is powered by a high power X-band magnetron and has a 17 keV 200 mA thermionic gun with a focus electrode for pulsing. A bi-periodic structure with on-axis coupling is used to minimise the radial size of the linac and to reduce the surface electric fields.

MOPB005	High Gradient Operation of 8 GeV C-Band Accelerator in SACLA	acceleration, laser, klystron, free-electron-laser	186
	T. Inagaki, C. Kondo, Y. Otake, T. Sakurai RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
	SACLA (SPring-8 angstrom compact free electron laser) is the X-ray free electron laser (XFEL) facility. In order to shorten the 8 GeV accelerator length, a C-band (5712 MHz) accelerator was employed. Since the accelerating gradient of C-band accelerating structure is 35 MV/m in nominal, the active accelerator length is 230 m. In total, 64 klystrons, 64 pulse compressors, and 128 accelerating structures are used. In order to withstand the high surface field (~ 100 MV/m), and to reduce the amount of dark current, which decreases the demagnetization effect of undulators, the accelerating structures are carefully fabricated in the factory.　After high power RF conditioning of 500 hours, the beam commissioning was started in February 2011. For night time of the commissioning, we continued the RF conditioning. The RF breakdown rate of the structure was steadily decreased. Now we operate the accelerator with the beam energy as much as 8.3 GeV, and the accelerating gradient of 37 MV/m in average. We found the amount of dark current is small enough. So far no trouble occurred in C-band RF components of 64 sets.

MOPB007	Study of Microbunching Instabilitity in the Linac of the Shanghai Soft X-Ray Free Electron Laser Facility	linac, impedance, FEL, simulation	189
	D. Huang, Q. Gu, M. Zhang SINAP, Shanghai, People's Republic of China
	The microbunching instability in the LINAC of a FEL facility has always been an issue which may degrade the quality of the electron beam. As the result, the whole facility may not be working properly. Shanghai soft X-ray FEL project (SXFEL), which is planned to start construction by the end of 2012, will be the first X-ray FEL facility in China. In this article, detailed study will be given based on the physical design of the facility to gain better understanding and control over the possible microbunching instability in SXFEL, which is critical to the success of the project. Moreover, the contribution of the possible plasma effects to the instability will also be studied by modifying the physical model of the longitudinal space charge (LSC) impedance.

MOPB011	Photoinjector of the EBTF/CLARA Facility at Daresbury	gun, laser, cavity, vacuum	192
	B.L. Militsyn, D. Angal-Kalinin, C. Hill, S.P. Jamison, J.K. Jones, J.W. McKenzie, K.J. Middleman, B.J.A. Shepherd, R.J. Smith, R. Valizadeh, A.E. Wheelhouse STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom N. Bliss, M.D. Roper STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
	A description is given of a photoinjector designed for Compact Linear Advanced Research Accelerator (CLARA) and Electron Beam Test Facility (EBTF), which will eventually be used to drive a compact FEL. The photoinjector is based on a 2.5 cell S-band photocathode RF gun operating with a copper photocathode and driven by a third harmonic of Ti: Sapphire laser (266 nm) installed in dedicated thermally stabilized room. The injector will be operated with laser pulses with an energy of up to 2 mJ, a pulse duration of 100 fs and initially a repetition rate of 10 Hz, with the aim of increasing this eventually to 400 Hz. At a field gradient of 100 MV/m provided by a 10 MW klystron the gun is expected to deliver beam pulses with energy of up to 6 MeV. Duration and emittance of electron bunches essentially depend on the bunch charge and vary from 0.1 ps at 20 pC to 5 ps at 200 pC and from 0.2 to 2 mm mrad respectively. Additional compression of the electron bunches will be provided with a velocity bunching scheme. For thermal stability the low energy part of the injector is mounted on an artificial granite support.

MOPB013	Experimental Results on the PHIL Photo-injector Test Stand at LAL	cathode, emittance, laser, gun	198
	R. Roux, F. Blot, J. Brossard, C. Bruni, S. Cavalier, J-N. Cayla, V. Chaumat, M. El Khaldi, A. Gonnin, P. Lepercq, E.N. Mandag, B. Mercier, H. Monard, C. Prevost, V. Soskov, A. Variola LAL, Orsay, France
	Since the first beam in November 2009 of the alphaX S-band RF gun, upgrades of the beamline have been carried out. Several YAG screens based transverse dimensions monitors have been installed as well as supplementary charge diagnostics. We will present a detailed experimental characterization of the RF gun performances such as emittance measurement using a solenoid scan and energy spread as a function of the RF phase. Most of the accelerator operation and experimental results have been carried out with a copper photo-cathode. PHIL being a test stand for photo-injectors, we have also tested a magnesium photo-cathode with the aim of higher charge per bunch thanks to its higher quantum efficiency. We will report on the results of this experiment. In May 2012, a new RF gun, the PHIN gun, will be installed. This gun which is also a S-band 2,5 cells is a copy of the one that LAL built for the CLIC Test Facility 3 at CERN. In the future, we plan to use this gun to produce a high charge up to 10nC with CsTe photo-cathodes introduced in the gun from a UHV transfer chamber. Preliminary tests and measurements of the beam produced by this gun with a copper photo-cathode will be presented.

MOPB014	Electron Model of a Dogbone RLA with Multi-Pass Arcs	linac, quadrupole, dipole, optics	201
	S.A. Bogacz, G.A. Krafft, V.S. Morozov, Y. Roblin JLAB, Newport News, Virginia, USA K.B. Beard Muons. Inc., USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Supported in part by USDOE STTR Grant DE-FG02-08ER86351 The design of a dogbone RLA with linear-field multi-pass arcs was earlier developed for accelerating muons in a Neutrino Factory and a Muon Collider. It allows for efficient use of expensive RF while the multi-pass arc design based on linear combined-function magnets exhibits a number of advantages over separate-arc or pulsed-arc designs. Such an RLA may have applications going beyond muon acceleration. This paper describes a possible straightforward test of this concept by scaling a GeV scale muon design for electrons. Scaling muon momenta by the muon-to-electron mass ratio leads to a scheme, in which a 4.35 MeV/c electron beam is injected in the middle of a 2.9 MeV/pass linac with two double-pass return arcs and is accelerated to 17.4 MeV/c in 4.5 passes. All spatial dimensions including the orbit distortion are scaled by a factor of 7.5, which arises from scaling the 200 MHz muon RF to a readily available 1.5 GHz. The footprint of a complete RLA fits in a 25x7 m area. The scheme utilizes only fixed field magnets for both injection and extraction. The hardware requirements are not very demanding making it straightforward to implement the scaled design using available equipment.

MOPB023	Progress on the Design and Construction of the 100 MeV / 100 kW Electron Linac for the NSC KIPT Neutron Source	linac, klystron, gun, neutron	222
	S. Pei, J. Cao, Y.L. Chi, B. Deng, C.D. Deng, H.S. Guo, D.Y. He, X. He, M. Hou, X.C. Kong, Q. Le, X. Li, J. Liu, R.L. Liu, W.B. Liu, K. Lv, C. Ma, H.Z. Ma, G. Pei, H. Song, L. Wang, S.H. Wang, X. Wang, Q. Yang, J. Yue, J.R. Zhang, F. Zhao, J.B. Zhao, J.X. Zhao, Z.S. Zhou IHEP, Beijing, People's Republic of China M.I. Ayzatskiy, I.M. Karnaukhov, V.A. Kushnir, V.V. Mytrochenko, A.Y. Zelinsky NSC/KIPT, Kharkov, Ukraine Y. Gohar ANL, Argonne, USA
	IHEP in China is designing and constructing a 100 MeV / 100 kW electron linac for NSC KIPT, which will be used as the driver of a neutron source based on a subcritical assembly. Recently, the physical design has been finalized. The chicane scheme instead of the RF chopper one has been selected. The mechanical design is on-going and will be finished in the very near future. The injector part of the machine has been installed in the experimental hall #2 of IHEP and is being commissioned and tested. The progress on the machine design and construction are reported, initial testing and commissioning results of the injector are also presented. *peisl@ihep.ac.cn

MOPB024	Beam Dynamics Simulation and Optimization for 10 MeV Superconducting e-Linac Injector for VECC-RIB Facility	linac, TRIUMF, gun, emittance	225
	A. Chakrabarti, S. Dechoudhury, V. Naik VECC, Kolkata, India F. Ames, R.A. Baartman, Y.-C. Chao, R.E. Laxdal, M. Marchetto, L. Merminga, F. Yan TRIUMF, Vancouver, Canada G. Goh SFU, Burnaby, BC, Canada
	Funding: This project is funded by Department of Atomic Energy, India In the first phase of ongoing collaboration between VECC (India) and TRIUMF (Canada) a 10 MeV superconducting electron linac injector will be installed at VECC. This will constitute a 100 keV DC thermionic gun with grid delivering pulsed electron beam at 650 MHz. Owing to low energy from the gun, a capture cryo-module (CCM) consisting of two β = 1 single cell elliptical cavities (frequency = 1.3 GHz) will be inserted before a 9-cell β = 1 elliptical cavity that will provide acceleration to 10 MeV. The present paper depicts the beam dynamics simulation and optimization of different parameters for the injector with a realistic simulated beam emittance from the electron gun.

MOPB029	Commissioning of the X-Band Test Area at SLAC	gun, cathode, laser, injection	234
	C. Limborg-Deprey, C. Adolphsen, M.P. Dunning, S. Gilevich, C. Hast, R.K. Jobe, D.J. McCormick, A. Miahnahri, T.O. Raubenheimer, A.E. Vlieks, D.R. Walz, S.P. Weathersby SLAC, Menlo Park, California, USA
	Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515. The X-Band Test Area (XTA) is being assembled in the NLCTA tunnel at SLAC to serve as a test facility for new X-Band RF guns. The first gun to be tested is an upgraded version of the 5.6 cell, 200 MV/m peak field X-band gun designed at SLAC in 2003 for the Compton Scattering experiment run in ASTA [1]. The XTA beamline is equipped with diagnostics to measure both the longitudinal phase space and the transverse phase space properties of the beam after it has reached 100 MeV. We will review design choices and present some early commissioning results. [1] A.E. Vlieks, et al. “Recent measurements and plans for the SLAC Compton X-ray source”, SLAC-PUB-11689, 2006. 10pp. Published in AIP Conf. Proc.807:481-490, 2006

MOPB032	Stabilization of the Beam Intensity in the Linac at the CTF3 CLIC Test Facility	linac, gun, controls, feedback	243
	A. Dubrovskiy JINR, Dubna, Moscow Region, Russia B.N. Bathe, S. Srivastava BARC, Mumbai, India F. Tecker CERN, Geneva, Switzerland
	A new electron beam stabilization system has been introduced in CTF3 in order to open new possibilities for CLIC beam studies in ultra-stable conditions and to provide a sustainable tool to keep the beam intensity and energy at its reference values for long term operations. The stabilization system is based on a pulse-to-pulse feedback control of the electron gun to compensate intensity deviations measured at the end of the injector and at the beginning of the linac. Thereby it introduces negligible beam distortions at the end of the linac and it significantly reduces energy deviations. A self-calibration mechanism has been developed to automatically configure the feedback controller for the optimum performance. The residual intensity jitter of 0.045% of the stabilized beam was measured whereas the CLIC requirement is 0.075%.

MOPB033	High Power Coupler Test for TRIUMF E-linac SC Cavities	vacuum, linac, TRIUMF, monitoring	246
	A.K. Mitra, Z.T. Ang, S. Calic, P.R. Harmer, S.R. Koscielniak, R.E. Laxdal, W.R. Rawnsley, R.W. Shanks TRIUMF, Vancouver, Canada
	TRIUMF has been funded to build an electron linac with a final energy of 50 MeV and 500 kW beam power using TESLA type 9 cell superconducting cavities operating at 1.3 GHz at 2 Kelvin. The e-linac consists of an electron gun, buncher cavity, injector cryomodule, and two main-linac cryomodules. The injector module has one 9-cell cavity whereas each of the accelerating main-linac cryomodules contains two 9-cell cavities. It is scheduled to install the injector and one main accelerating cryomodule by 2014. Six power couplers, each rated for 60 kW cw, have been procured for three cavities. The injector cryomodule will be fed by a 30 kW cw inductive Output Tube (IOT) and the accelerating cryomodule will be powered by a 290 kW cw klystron. In order to install the power couplers in the cavities, they are to be assembled and conditioned with high power rf source. A power coupler test station has been built and tests of two power couplers have began. A 30 kW IOT has been commissioned to full output power and it will be used for the power coupler test. In this paper, test results of the rf conditioning of the power couplers under pulse and cw mode will be described.

MOPB034	Novel Technique of Suppressing TBBU in High-energy ERLs	linac, HOM, SRF, lattice	249
	V. Litvinenko BNL, Upton, Long Island, New York, USA
	Energy recovery linacs (ERLs) is emerging generation of accelerators promising revolutionize the fields of high-energy physics and photon sciences. One potential weakness of these devices is transverse beam-breakup instability, which may severely limit available beam current. In this paper I am presenting new idea [1] developed for high-energy ERL which could be used for eRHIC, LHeC and, potentially, ILC: a concept of using main ERL linacs and natural chromaticity to suppressing TBBU instabilities by simplifying an ERL lattice. As demonstration of this method, I present tow specific example of eRHIC and LHeC ERLs. [1] V.N. Litvinenko, Chromaticity of the lattice and beam stability in energy recovery linacs, submitted to PR ST-AB

MOPB035	The Linear Accelerating Structure Development for HLS Upgrade	cavity, linac, injection, bunching	252
	K. Jin, Y. Hong, G. Huang, D. Jia, S.C. Zhang USTC/NSRL, Hefei, Anhui, People's Republic of China
	Hefei Light Source (HLS) is mainly composed of an 800 MeV electron storage ring and a 200 MeV constant-impedance Linac functioning as its injector. A new Linac is developed in view of the Full Energy Injection and the Top-up Injection scheme will be adopted in the HLS upgrade. In this paper, an 800 MeV linear accelerating system construction, the constant-gradient structure design and the symmetry couplers consideration will be described in detail. The manufacture technology, the RF measurement, the high power test results and the accelerating system operation are presented.

MOPB038	Single Shot Bunch-by-Bunch Beam Emittance Measurement of the SPring-8 Linac	linac, injection, emittance, dipole	261
	Y. Shoji, K. Takeda LASTI, Hyogo, Japan
	Bunch by bunch emittance of a single shot beam from the SPring-8 electron linac was measured. The linac is operated as an injector to the electron storage ring, NewSUBARU. A high beam stability is required for the stable top-up injection into the ring with a small acceptance. We used the electron ring as a part of the measurement system. The electron beam from the linac was injected into the ring and circulated for many turns. The beam profiles were recorded by a dual-sweep streak camera using the visible light in the ring. The fast sweep separated the bunches in 1 ns macro pulse and the slow sweep separated the profiles at different revolutions. It enabled a multi-record of beam profiles in one camera frame. Betatron oscillation in the ring produced the phase space rotation for the reconstruction of the beam emittance. The ring parameters were optimized for the measurement because the beam storage was not necessary. A stability of the linac beam was evaluated from the shot by shot fluctuation of the emittance and the bunch structure. We also compared the emittances of a front bunch and a rear bunch in the same pulse.

MOPB041	Advances in Beam Tests of Dielectric Based Accelerating Structures	wakefield, acceleration, laser, linac	264
	A. Kanareykin, S.P. Antipov, J.E. Butler, C.-J. Jing Euclid TechLabs, LLC, Solon, Ohio, USA W. Gai ANL, Argonne, USA V. Yakimenko BNL, Upton, Long Island, New York, USA
	Funding: US Department of Energy Diamond is being evaluated as a dielectric material for dielectric loaded accelerating structures. It has a very low microwave loss tangent, high thermal conductivity, and supports high RF breakdown fields. We report on progress in our recent beam tests of the diamond based accelerating structures of the Ka-band and THz frequency ranges. Wakefield breakdown test of a diamond-loaded accelerating structure has been carried out at the ANL/AWA accelerator. The high charge beam from the AWA linac (~70 nC, σ_z = 2.5 mm) was passed through a rectangular diamond loaded resonator and induce an intense wakefield. A groove is cut on the diamond to enhance the field. Electric fields up to 0.3 GV/m has been detected on the diamond surface to attempt to initiate breakdown. A surface analysis of the diamond has been performed before and after the beam test. Wakefield effects in a 250 GHz planar diamond accelerating structure has been observed at BNL/ATF accelerator as well. We have directly measured the mm-wave wake fields induced by subpicosecond, intense relativistic electron bunches in a diamond loaded accelerating structure via the dielectric wake-field acceleration mechanism.

MOPB046	A 10 MeV L-band Linac for Irradiation Applications in China	linac, gun, klystron, simulation	276
	G. Pei, Y.L. Chi, M.H. Dai, D.Y. He, X. He, X. Li, J. Liu, C. Ma, X. Wang, X.W. Yang, C.H. Yu, F. Zhao, J. Zhao, Z.S. Zhou IHEP, Beijing, People's Republic of China Y. Feng, H. Huang, S. Shi, E. Tang, X. Yang, Q. Yuan, Z. Zhu Institute of High Energy Physics (IHEP), People's Republic of China Z. Li, X. Zhang Wuxi EL PONT Radiation Technology Ltd, Wuxi, People's Republic of China
	The electron linear accelerator has wide applications, and the demands are keeping growing for the irradiation applications in China. A high beam power 10 MeV L-band Linac has been developed recently as a joint venture of Institute of High Energy Physics and EL-PONT Company. The Thales TH2104U klystron, 3 A thermionic electron gun and three meter L-band disk-loaded constant impedance RF structure are adopted. A stable electron beam of 10 MeV, 40 kW has been obtained in the last May with a microwave to beam efficiency of about 65%. In this paper we will present the detailed design issues and beam commissioning.

MOPB047	Applications of Compact Dielectric Based Accelerators	coupling, multipactoring, wakefield, impedance	279
	C.-J. Jing, S.P. Antipov, A. Kanareykin, P. Schoessow Euclid TechLabs, LLC, Solon, Ohio, USA M.E. Conde, W. Gai, J.G. Power ANL, Argonne, USA
	Important progress on the development of dielectric based accelerators has been made experimentally and theoretically in the past few years. One advantage of dielectric accelerators over the metallic counterparts is its compact size, which may attract some applications in industrial or medical accelerators. In this article, we discuss the design and technologies of dielectric based accelerators toward these needs.

MOPB048	Linear Accelerator Based on Parallel Coupled Accelerating Structure	cavity, controls, focusing, klystron	282
	A.E. Levichev, A.M. Barnyakov, V.M. Pavlov BINP SB RAS, Novosibirsk, Russia Y.D. Chernousov ICKC, Novosibirsk, Russia V. Ivannikov, I.V. Shebolaev ICKC SB RAS, Novosibirsk, Russia
	Accelerating stand based on parallel coupled accelerating structure and electron gun is developed and produced. The structure consists of five accelerating cavities. The RF power feeding of accelerating cavities is provided by common exciting cavity which is performed from rectangular waveguide loaded by reactive pins. Operating frequency is 2450 MHz. Electron gun is made on the basis of RF triode. Linear accelerator was tested with different working regimes. The obtained results are following: energy is up to 4 MeV, accelerating current is up to 300 mA with pulse duration of 2.5 ns on the half of the width; energy is up to 2.5 MeV, accelerating current is up to 100 mA with pulse duration of 5 μs; energy is up to 2.5 MeV, accelerating current is up to 120 mA with pulse duration of 5 μs and beam capture of 100%. The descriptions of the accelerator elements are given in the report. The features of the parallel coupled accelerating structure are discussed. The results of the measuring accelerator’s parameters are presented.

MOPB049	Design of Compact C-Band Standing-Wave Accelerator for Medical Radiotherapy	coupling, bunching, focusing, cavity	285
	H. Yang, M.-H. Cho, W. Namkung POSTECH, Pohang, Kyungbuk, Republic of Korea S.H. Kim ANL, Argonne, USA J.-S. Oh NFRI, Daejon, Republic of Korea
	Funding: Work supported by POSTECH Physics BK21 Program. We design a C-band standing-wave accelerator for an X-ray and electron source of medical radiotherapy. The accelerator system is operated two modes, using the X-ray and electron beams. Since two modes require different energy, the accelerator is capable of producing 6-MeV, 100-mA pulsed electron beams with peak 2-MW RF power, and 7.5-MeV, 50 mA electron beams with peak 2.5-MW RF power. The beam is focused by less than 1 mm without external magnets. The accelerating structure is a bi-periodic and on-axis-coupled structure with a built-in bunching section, which consists of 3 bunching cells, 14 normal cells and a coupling cell. It is operated with the π/2-mode standing-wave. The bunching cells are designed to enhance the RF phase focusing. Each cavity is designed by the MWS code within 3% inter-cell coupling. In this paper, we present design details of RF cavities and the beam dynamics.

MOPB051	Changing Attitude to Radiation Hazards and Consequent Opportunities for LINAC Applications	radiation, linac, background, status	288
	Y. Socol Falcon Analytics, Netanya, Israel
	High-energy LINACs unavoidably yield ionizing radiation. This fact makes them subject to strict regulations and considerably limits applications. During the last two decades the attitude to ionizing radiation hazards seems to become more balanced, as opposed to "radiophobia" of the Cold-War era. Scientifically, the linear no-threshold (LNT) model of radiation damage is more and more questioned. Moreover, the hypotheses of radiation hormesis - beneficial effect of low-dose radiation - is studied. While this scientific debate has not yet given fruit regarding radiation regulation and policy, we may expect this in near to middle term. Namely, the ALARA (as low as reasonably achievable) demand is anticipated to be substituted by some tolerance level, which in turn is anticipated to be very high according to the present standards. The presentation will review the present status of the radiation-hazard debate, and outline anticipated opportunities for LINAC applications, like compact designs and wider industrial outreach.

MOPB056	Multipacting Analysis of High-Velocity Superconducting Spoke Resonators	cavity, site, simulation, superconductivity	303
	C.S. Hopper, J.R. Delayen ODU, Norfolk, Virginia, USA
	Some of the advantages of superconducting spoke cavities are currently being investigated for the high-velocity regime. When determining a final, optimized geometry, one must consider the possible limiting effects multipacting could have on the cavity. We report on the results of analytical calculations and numerical simulations of multipacting electrons in superconducting spoke cavities and methods for reducing their impact.

MOPB061	The New 2nd Generation SRF R&D Facility at Jefferson Lab: TEDF	SRF, cryomodule, cavity, cryogenics	315
	C.E. Reece, A.V. Reilly JLAB, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The US Department of Energy has funded a near-complete renovation of the SRF-based accelerator research and development facilities at Jefferson Lab. The project to accomplish this, the Technical and Engineering Development Facility (TEDF) Project has completed the first of two phases. An entirely new 3,300 m² purpose-built SRF technical work facility has been constructed and is being occupied in summer of 2012. All SRF work processes with the exception of cryogenic testing has been relocated into the new building. All cavity fabrication, processing, thermal treatment, chemistry, cleaning, and assembly work is collected conveniently into a new LEED-certified building. An innovatively designed 750 m² cleanroom/chemrooms suite provides long-term flexibility for support of multiple R&D and construction projects as well as continued process evolution. The detailed characteristics of this perhaps first 2nd-generation SRF facility will be described.

MOPB063	Superconducting RF Linac for eRHIC	cavity, linac, SRF, HOM	321
	S.A. Belomestnykh, I. Ben-Zvi, J.C. Brutus, H. Hahn, D. Kayran, V. Litvinenko, G.J. Mahler, G.T. McIntyre, V. Ptitsyn, R. Than, J.E. Tuozzolo, W. Xu, A. Zaltsman BNL, Upton, Long Island, New York, USA S.A. Belomestnykh Stony Brook University, Stony Brook, USA
	Funding: Work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE. eRHIC will collide high-intensity hadron beams from RHIC with 50-mA electron beam from a six-pass 30-GeV Energy Recovery Linac (ERL), which will utilize 704 MHz superconducting RF accelerating structures. This presentation describes the eRHIC SRF linac requirements, layout and parameters, 5-cell SRF cavity with a new HOM damping scheme, project status and plans.

MOPB064	Developing of Superconducting RF Guns at BNL	gun, SRF, cathode, cavity	324
	S.A. Belomestnykh, Z. Altinbas, I. Ben-Zvi, J.C. Brutus, D.M. Gassner, H. Hahn, L.R. Hammons, J.P. Jamilkowski, D. Kayran, J. Kewisch, V. Litvinenko, G.J. Mahler, G.T. McIntyre, D. Pate, D. Phillips, T. Rao, S.K. Seberg, T. Seda, B. Sheehy, J. Skaritka, K.S. Smith, R. Than, J.E. Tuozzolo, E. Wang, Q. Wu, W. Xu, A. Zaltsman BNL, Upton, Long Island, New York, USA S.A. Belomestnykh, J. Dai, M. Ruiz-Osés, T. Xin Stony Brook University, Stony Brook, USA C.H. Boulware, T.L. Grimm Niowave, Inc., Lansing, Michigan, USA A. Burrill JLAB, Newport News, Virginia, USA R. Calaga CERN, Geneva, Switzerland M.D. Cole, A.J. Favale, D. Holmes, J. Rathke, T. Schultheiss, A.M.M. Todd AES, Medford, NY, USA X. Liang SBU, Stony Brook, New York, USA
	Funding: Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE. The work at Niowave is supported by the US DOE under SBIR contract No. DE-FG02-07ER84861. BNL is developing several superconducting RF guns for different applications. The first gun is based on a half-cell 1.3 GHz elliptical cavity. This gun is used to study generation of polarized electrons from GaAs photocathodes. The second gun, also of a half-cell elliptical cavity design, operates at 704 MHz and is designed to produce high average current electron beam for the ERL prototype from a multi-alkali photocathodes. The third gun is of a quarter-wave resonator type, operating at 112 MHz. This gun will be used for photocathode studies, including a diamond-amplified cathode, and to generate high charge, low repetition rate beam for the coherent electron cooling experiment. In this presentation we will briefly describe the gun designs, present recent test results and discuss future plans.

MOPB069	Study of HPR Created Oxide Layer at Nb Surfaces	SRF, vacuum, cavity, ion	336
	P.V. Tyagi Sokendai, Ibaraki, Japan H. Hayano, S. Kato, T. Saeki, M. Sawabe KEK, Ibaraki, Japan
	The performance of superconducting radio frequency (SRF) niobium (Nb) cavities strongly depends on final surface condition. Therefore the surface preparation of these SRF cavities often becomes critical. The preparation of surface includes two steps; surface chemistry (in order to get a smooth surface) and cleaning/rinsing (in order to remove contaminants left after the surface chemistry). As high pressure rinsing (HPR) with ultra pure water (UPW) is most commonly used surface cleaning method after the surface chemistry, it's very interesting to characterize the Nb surfaces after HPR. Results of our surface characterization done by XPS (x-ray photoelectron spectroscopy) with depth profiling show the presence of a thicker oxide surface characterization results show the presence of a thicker oxide layer at Nb surface as an outcome of HPR. In this article, we report the production of oxide layer (FWHM thickness) based on different conditions such as the pressures and doses.

MOPB079	Normal Conducting Deflecting Cavity Development at the Cockcroft Institute	cavity, beam-loading, wakefield, damping	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	klystron, coupling, controls, FEL	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	acceleration, linac, impedance, proton	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.

MOPB084	Design of a C-band Disk-loaded Type Accelerating Structure for a Higher Pulse Repetition Rate in the SACLA Accelerator.	cavity, laser, wakefield, accelerating-gradient	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.

MOPB089	X-Ray Local Energy Spectrum Measurement at Tsinghua Thomson Scattering X-Ray Source (TTX)	scattering, simulation, laser, photon	383
	Y.-C. Du, J.F. Hua, W.-H. Huang, C.-X. Tang, L.X. Yan, H. Zha, Z. Zhang TUB, Beijing, People's Republic of China
	Thomson scattering X-ray source, in which the TW laser pulse is scattered by the relativistic electron beam, can provide ultra short, monochromatic, high flux, tunable polarized hard X-ray pulse which is can widely used in physical, chemical and biological process research, ultra-fast phase contrast imaging, and so on. Since the pulse duration of X-ray is as short as picosecond and the flux in one pulse is high, it is difficult to measure the x-ray spectrum. In this paper, we present the X-ray spectrum measurement experiment on Tsinghua Thomson scattering. The preliminary experimental results shows the maximum X-ray energy is about 47 keV, which is agree well with the simulations.

MOPB093	The Upgraded Argonne Wakefield Accelerator Facility (AWA): a Test-Bed for the Development of High Gradient Accelerating Structures and Wakefield Measurements	wakefield, gun, linac, acceleration	392
	M.E. Conde, D.S. Doran, W. Gai, R. Konecny, W. Liu, J.G. Power, Z.M. Yusof ANL, Argonne, USA S.P. Antipov, C.-J. Jing Euclid TechLabs, LLC, Solon, Ohio, USA E.E. Wisniewski Illinois Institute of Technology, Chicago, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy under contract No. DE-AC02-06CH11357. Electron beam driven wakefield acceleration is a bona fide path to reach high gradient acceleration of electrons and positrons. With the goal of demonstrating the feasibility of this concept with realistic parameters, well beyond a proof-of-principle scenario, the AWA Facility is currently undergoing a major upgrade that will enable it to achieve accelerating gradients of hundreds of MV/m and energy gains on the order of 100 MeV per structure. A key aspect of the studies and experiments carried out at the AWA facility is the use of relatively short RF pulses (15 – 25 ns), which is believed to mitigate the risk of breakdown and structure damage. The upgraded facility will utilize long trains of high charge electron bunches to drive wakefields in the microwave range of frequencies (8 to 26 GHz), generating RF pulses with GW power levels.

TU2A02	Overview of SACLA Machine Status	undulator, laser, gun, emittance	427
	Y. Otake RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
	SACLA of an X-ray free-electron laser has been constructed and was successfully lased at 0.06 nm in 2011. SACLA mainly comprises a low-emittance thermionic electron gun, an 8-GeV linear accelerator using C-band (5712 MHz) cavities and 18 in-vacuum undulators. The concept to develop this machine is compactness compared with the other machine, such as LCLS with the length of more than 1 km. Stable X-ray lasing up to 0.06 nm as also the concept demands extreme stable accelerator components, such as 50 fs temporal stability at a cavity in an injector. We now realized a 700 m compact machine by a low-emittance at the electron gun, an accelerating gradient of more than 35 MV/m with the C-band accelerator, and the short-period undulators. The continuous lasing for more than several days is strongly supported by these stable components and small operator‘s trimming, and also established by reduction of perturbation sources to laser instability. SACLA is regularly operated for user experiments, such as the imaging with extreme amount of data. This presentation introduces the machine performance, the reduction of the perturbation sources and the operation of SACLA.
	Slides TU2A02 [28.971 MB]

TU2A03	LCLS Operation Experience and LCLS-II Design	undulator, linac, photon, FEL	432
	T.O. Raubenheimer SLAC, Menlo Park, California, USA
	This talk will report the operations experience at LCLS and will describe the LCLS-II, a new X-ray FEL facility that uses the middle 1/3 of the SLAC linac as compared to the LCLS which uses the last 1/3 of the SLAC linac.
	Slides TU2A03 [4.761 MB]

TU2A04	High Current ERL at BNL	linac, gun, SRF, cavity	437
	I. Ben-Zvi BNL, Upton, Long Island, New York, USA
	The electron hadron collider eRHIC will collide polarized and unpolarized electrons with a current of 50 mA and energy in the range of 5 GeV to 30 GeV with hadron beams, including heavy ions or polarized light ions of the RHIC storage ring. The electron beam will be generated in an energy recovery linac contained inside the RHIC tunnel, comprising six passes through two linac section of about 2.5 GeV each. The electron ERL poses many challenges in term of a high-current high-polarization electron gun, HOM damping in the linac, crab cavities, harmonic cavities and beam stability.
	Slides TU2A04 [2.227 MB]

TUPLB01	The Swiss FEL RF Gun: RF Design and Thermal Analysis	gun, coupling, cathode, linac	442
	J.-Y. Raguin, M. Bopp, A. Citterio, A. Scherer PSI, Villigen, Switzerland
	We report here on the design of a dual-feed S-band 2.5 cell RF gun, developed in the framework of SwissFEL, capable of operating at 100 Hz repetition rate. As in the LCLS RF gun, z-coupling, to reduce the pulsed surface heating, and a racetrack coupling cell shape, to minimize the quadrupolar component of the fields, have been adopted. The cell lengths and the iris thicknesses are as in the PHIN gun operating at CERN. However the irises aperture has been enlarged to obtain a frequency separation between the operating π mode and the π/2 mode higher than 15 MHz. An amplitude modulation scheme of the RF power, which allows one to obtain a flat plateau of 150 ns for multibunch operation and a reduced average power is presented as well. With an RF pulse duration of 1μs it is shown that operation at 100 MV/m and 100 Hz repetition rate is feasible with very reasonable thermal stresses.
	Slides TUPLB01 [1.679 MB]

TUPLB05	Computational Model Analysis for Experimental Observation of Optical Current Noise Suppression below the Shot-Noise Limit	plasma, linac, simulation, beam-transport	451
	A. Gover University of Tel-Aviv, Faculty of Engineering, Tel-Aviv, Israel A. Nause University of Tel Aviv, Tel Aviv, Israel
	Funding: We acknowledge support of the Israel Science Foundation grant We report first demonstration of optical frequency current shot-noise suppression in a relativistic e-beam. This process is made possible by collective Coulomb interaction between the electrons of a cold intense beam during beam drift, and is essentially a process of longitudinal beam-plasma oscillation [1]. Suppression of beam current noise below the classical “shot-noise” level has been known in the microwave tubes art [2]. This is the first time that it is demonstrated in the optical regime. We predict that the scheme can be extended to the XUV and possibly to shorter wavelengths with further development of technology. The fundamental current shot-noise determines the level of incoherent spontaneous radiation emission from electron-beam optical radiation sources and SASE-FELs [3]. Suppressing shot-noise would make it possible to attain spontaneous emission sub-radiance [4] and surpass the classical coherence limits of seed-injected FELs. The effect was demonstrated by measuring sub-linear growth as a function of current of the OTR Radiation. This finding indicates that the beam charge homogenizes due to the collective interaction, and its distribution becomes sub-Poissonian. [1] A. Gover, E. Dyunin, PRL, 102, 154801, 2009 [2] H. Haus, N. Robinson, Proc. IRE, 43, 981 (1955) [3] P. Emma, et al , Nature Photonics 4, 641 (2010) [4] A. Dicke, Phys. Rev. 93, 99 (1954)

TUPLB07	Reduced-beta Cavities for High-intensity Compact Accelerators	cavity, ion, niobium, heavy-ion	458
	Z.A. Conway, S.M. Gerbick, M. Kedzie, M.P. Kelly, J.W. Morgan, R.C. Murphy, P.N. Ostroumov, T. Reid ANL, Argonne, USA
	Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under contract number DE-AC02-06CH11357 and WFO 8R268. This paper reports on the development and testing of a superconducting quarter-wave and a superconducting half-wave resonator. The quarter-wave resonator is designed for β = 0.077 ions, operates at 72 MHz and can provide more than 7.4 MV of accelerating voltage at the design beta, with peak surface fields of 164 mT and 117 MV/m. Operation was limited to this level not by RF surface defects but by our available RF power and administrative limits on x-ray production. A similar goal is being pursued in the development of a half-wave resonator designed for β = 0.29 ions and operated at 325 MHz.

TUPLB09	Design and Beam Test of Six-electrode BPMs for Second-order Moment Measurement	factory, multipole, linac, storage-ring	464
	K. Yanagida, H. Hanaki, S. Suzuki JASRI/SPring-8, Hyogo-ken, Japan
	In the SPring-8 linac, four-electrode beam position monitors (BPMs) have been utilized for the measurement of the transverse first-order moments, which correspond to the centroids of beam charge distributions. We have planed to measure the transverse second-order moments of beams to obtain information of beam optics and its energy deviations during the top-up beam injection without destruction of beams. Therefore, six-electrode BPMs with circular and quasi-ellipse cross-sections have been developed on the basis of a newly introduced theory. A low-noise signal processor for the six-electrode BPM has also been developed to perform fine measurement. We expected the following resolutions determined by the S/N ratio of the circuit; the first order moments (beam positions) > 1 μm, and the second order moments with a size > 110 μm. The first beam test was carried out using the six-electrode BPM with circular cross-section and the old signal processor. The measured sensitivities and resolutions of the second-order moments showed good agreement with the theory.
	Slides TUPLB09 [8.248 MB]

TUPLB10	Non-destructive Real-time Monitor to Measure 3D-bunch Charge Distribution with Arrival Timing to Maximize 3D Overlapping for HHG-seeded EUV-FEL	FEL, laser, feedback, optics	467
	H. Tomizawa, K. Ogawa, T. Sato, M. Yabashi RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan M. Aoyama JAEA/Kansai, Kyoto, Japan A. Iwasaki, S. Owada The University of Tokyo, Tokyo, Japan S. Matsubara, Y. Okayasu, T. Togashi JASRI/SPring-8, Hyogo, Japan T. Matsukawa, H. Minamide RIKEN ASI, Sendai, Miyagi, Japan E. Takahashi RIKEN, Saitama, Japan
	Non-destructive, shot-by-shot real-time monitors have been developed to measure 3D bunch charge distribution (BCD). This 3D monitor has been developed to monitor 3-D overlapping electron bunches and higher harmonic generation (HHG) pulses in a seeded VUV-FEL. This ambitious monitor is based on an Electro-Optic (EO) multiple sampling technique in a manner of spectral decoding that is non-destructive and enables real-time measurements of the longitudinal and transverse BCD. This monitor was materialized in simultaneously probing eight EO crystals that surround the electron beam axis with a radial polarized and hollow EO-probe laser pulse. In 2009, the concept of 3D-BCD monitor was verified through electron bunch measurements at SPring-8. The further target of the temporal resolution is ~30 fs (FWHM), utilizing an organic EO crystal (DAST) instead of conventional inorganic EO crystals (ZnTe, GaP, etc.) The EO-sampling with DAST crystal is expected to measure a bunch length less than 30 fs (FWHM). In 2011, the first bunch measurement with an organic EO crystal (DAST) was successfully demonstrated in the VUV-FEL accelerator at SPring-8.
	Slides TUPLB10 [2.713 MB]

TUPB005	Computational Model Analysis for Experimental Observation of Optical Current Noise Suppression Below the Shot-noise Limit	plasma, linac, simulation, beam-transport	482
	A. Gover University of Tel-Aviv, Faculty of Engineering, Tel-Aviv, Israel A. Nause University of Tel Aviv, Tel Aviv, Israel
	Funding: We acknowledge support of the Israel Science Foundation grant We report first demonstration of optical frequency current shot-noise suppression in a relativistic e-beam. This process is made possible by collective Coulomb interaction between the electrons of a cold intense beam during beam drift, and is essentially a process of longitudinal beam-plasma oscillation.[1] Suppression of beam current noise below the classical “shot-noise” level has been known in the microwave tubes art [2]. This is the first time that it is demonstrated in the optical regime. We predict that the scheme can be extended to the XUV and possibly to shorter wavelengths with further development of technology. The fundamental current shot-noise determines the level of incoherent spontaneous radiation emission from electron-beam optical radiation sources and SASE-FELs [3]. Suppressing shot-noise would make it possible to attain spontaneous emission sub-radiance [4] and surpass the classical coherence limits of seed-injected FELs. The effect was demonstrated by measuring sub-linear growth as a function of current of the OTR Radiation. This finding indicates that the beam charge homogenizes due to the collective interaction, and its distribution becomes sub-Poissonian. [1] A. Gover, E. Dyunin, PRL, 102, 154801, 2009 [2] H. Haus, N. Robinson, Proc. IRE, 43, 981 (1955) [3] P. Emma, et al , Nature Photonics 4, 641 (2010) [4] A. Dicke, Phys. Rev. 93, 99 (1954)

TUPB008	Major Trends in Linac Design for X-ray FELs	FEL, linac, cathode, emittance	489
	A. Zholents ANL, Argonne, USA
	Funding: This work was supported by the U.S. Department of Energy under Contract No. DE-AC02-06CH11357. Major trends in the contemporary linac designs for x-ray free-electron lasers (XFELs) are outlined starting with identification of the key performance parameters, continuing with considerations of the design options for the electron gun and linac, and finishing with electron beam manipulation in the phase space.

TUPB010	The Swiss FEL RF Gun: RF Design and Thermal Analysis	gun, coupling, cathode, linac	495
	J.-Y. Raguin, M. Bopp, A. Citterio, A. Scherer PSI, Villigen, Switzerland
	We report here on the design of a dual-feed S-band 2.5 cell RF gun, developed in the framework of SwissFEL, capable of operating at 100 Hz repetition rate. As in the LCLS RF gun, z-coupling, to reduce the pulsed surface heating, and a racetrack coupling cell shape, to minimize the quadrupolar component of the fields, have been adopted. The cell lengths and the iris thicknesses are as in the PHIN gun operating at CERN. However the irises aperture has been enlarged to obtain a frequency separation between the operating π mode and the π/2 mode higher than 15 MHz. An amplitude modulation scheme of the RF power, which allows one to obtain a flat plateau of 150 ns for multibunch operation and a reduced average power is presented as well. With an RF pulse duration of 1μs it is shown that operation at 100 MV/m and 100 Hz repetition rate is feasible with very reasonable thermal stresses.

TUPB013	Update on the Commissioning Effort at the SwissFEL Injector Test Facility	emittance, laser, quadrupole, optics	504
	T. Schietinger PSI, Villigen, Switzerland
	The SwissFEL Injector Test Facility at the Paul Scherrer Institute is the principal test bed and demonstration plant for the SwissFEL project, which aims at realizing a hard-X-ray Free Electron Laser by 2017. Since the spring of 2012 the photoinjector facility has been running with all RF cavities in full operation, allowing beam characterization at energies around 230 MeV with bunch charges between 10 and 200 pC. We give an overview of recent commissioning efforts with particular emphasis on efforts to optimize the emittance of the uncompressed beam.

TUPB014	Comparative Design of Single Pass, Photo-cathode RF-LINAC FEL for the THz Frequency Range: Self Amplification vs. Enhanced Super-radiance	FEL, radiation, linac, wiggler	507
	Yu. Lurie, Y. Pinhasi Ariel University Center of Samaria, Faculty of Engineering, Ariel, Israel
	Self amplified spontaneous emission and enhanced super-radiance are discussed and compared as possible configurations in the construction of a single-pass, photo-cathode RF-LINAC FEL source for THz radiation, being developed in Ariel University Center of Samaria. Numerical simulations carried out using 3D, space-frequency approach demonstrate the charge squared dependence of the radiation power in both cases, the characteristic typical to super-radiant emission. The comparison reveals a high efficiency of an enhanced super-radiance FEL, which however can only be achieved with ultra-short (the radiation wavelength long or shorter) drive electron beam bunches at a proper energy chirping.

TUPB021	Study of Plasma Effect in Longitudinal Space Charge Induced Microbunching Instability	plasma, impedance, linac, space-charge	522
	D. Huang, Q. Gu SINAP, Shanghai, People's Republic of China K.Y. Ng Fermilab, Batavia, USA
	The longitudinal space charge (LSC) plays an important role in introducing the microbunching instability in the LINAC of a free electron laser (FEL) facility. The current model of LSC impedance [1] derived from the fundamental electromagnetic theory [2] is widely used to explain the growth of the microbunching instability [3]. However, in the case of highly bright relativistic electron beams, the plasma effect starts to play a role. In this article, the basic model of LSC impedance including the plasma effect is built , and the modifications to the microbunching instability based on the new model are discussed in various conditions. [1] Marco Venturini, Phys Rev. ST Accel. Beams 11, 034401 (2008) [2] J. D. Jackson, Classical Electrodynamics (Wiley, 1999) [3] Z. Huang, et. al., Phys, Rev. ST Accel. Beams 7, 074401 (2004)

TUPB022	A Passive Linearizer for Bunch Compression	FEL, linac, laser, emittance	525
	Q. Gu, M. Zhang, M.H. Zhao SINAP, Shanghai, People's Republic of China
	In high gain free electron laser (FEL) facility design and operation, a high bunch current is required to get lasing with a reasonable gain length. Because of the current limitation of the electron source due to the space charge effect, a compression system is commonly used to compress the electron beam to the exact current needed. Before the bunch compression, the nonlinear energy spread due to the finite bunch length should be compensated; otherwise the longitudinal profile of bunch will be badly distorted. Usually an X band accelerating structure is used to compensate the nonlinear energy spread while decelerating the beam. For UV FEL facility, the X band system is too expensive comparing to the whole facility. In this paper, we present a corrugated structure as a passive linearizer, and the preliminary study of the beam dynamics is also shown.

TUPB023	The Optimization of RF Deflector Input Power Coupler	coupling, emittance, simulation, diagnostics	528
	A.Yu. Smirnov, O.A. Adonev, P.V. Binyukov, N.P. Sobenin MEPhI, Moscow, Russia
	This paper concerns the investigation of different types of input power cell for S-band RF electron deflector. This device serving for slice emittance diagnostics is a disc-loaded waveguide which operates with TE11-like wave in traveling wave regime with 120 deg phase shift per cell. Since this deflector meets the restriction on its length and has to provide high enough deflecting potential to a particle during its flight time it is significant to increase the transversal field strength in coupling cell or to shorten it so that the deflecting potential remains constant. The total structure consists of 14 regular cells and two couplers. As it is now all cells have the same length equal to D=33.34 mm and the field in couplers is lower than that of regular cells. In this paper different length are considered and numerically simulated in order to choose the best one.

TUPB026	Measurements of a Reduced Energy Spread of a Recirculating Linac by Non-isochronous Beam Dynamics	recirculation, linac, synchrotron, acceleration	531
	F. Hug, C. Burandt, M. Konrad, N. Pietralla TU Darmstadt, Darmstadt, Germany R. Eichhorn Cornell University, Ithaca, New York, USA
	Funding: supported by DFG through SFB 634 The Superconducting Linear Accelerator S-DALINAC at the University of Darmstadt (Germany) is a recirculating linac with two recirculations providing beams for measurements in nuclear physics at small momentum transfers. For these experiments an energy spread of better than 10^-4 (rms) is needed. Currently acceleration in the linac section is done on crest of the accelerating field. The recirculation path is operated achromatic and isochronous. In this recirculation scheme the energy spread of the resulting beam in the ideal case is determined by the electron bunch length. Taking into account the stability of the RF system the energy spread increases drastically to more than 10^-3 (rms). We will present a new non-isochronous recirculation scheme which helps cancelling out these errors from the rf-control. This scheme uses longitudinal dispersion in the recirculation paths and an acceleration off-crest with a certain phase with respect to the maximum. We will present results of the commissioning of the new system including measurements of the longitudinal dispersion in the recirculation arcs as well as measurements of the resulting energy spread using an electron spectrometer.

TUPB041	Scattering of H⁻ Stripped Electrons from SEM Grids and Wire Scanners at the CERN LINAC4	simulation, scattering, linac, polarization	567
	F. Roncarolo, E. Chevallay, M. Duraffourg, G.J. Focker, C. Heßler, U. Raich, VC. Vuitton, F. Zocca CERN, Geneva, Switzerland B. Cheymol ESS, Lund, Sweden
	At the CERN LINAC4, wire grids and scanners will be used to characterize the H⁻ beam transverse profile at different stages along the acceleration to 160 MeV. The wire signal will be determined by the balance between secondary emission and number of charges stopped in the wire, which will depend on the wire material and diameter, the possible choice of biasing (DC) the wires and the beam energy. The outermost electrons of H⁻ ions impinging on a wire are stripped in the first nanometers of material. A portion of such electrons are scattered away from the wire and can reach the neighboring wires. In addition, scattered electrons hitting the surrounding beam pipe generate secondary electrons that can also perturb the measurement. Monte Carlo simulations, analytical calculations and a laboratory experiment allowed quantifying the amount of scattering and the scattered particles distributions. The experiment was based on 70 keV electrons, well reproducing the case of 128 MeV H⁻ ions. For all the LINAC4 simulated cases the predicted effect on the beam size reconstruction results in a relative error of less than 5%.

TUPB056	The Multipacting Simulation for the New-shaped QWR using TRACK3P	cavity, simulation, accelerating-gradient, niobium	603
	C. Zhang, S. He, Y. He, S.C. Huang, Y.L. Huang, T.C. Jiang, R.X. Wang, M.X. Xu, Y.Z. Yang, W.M. Yue, S.H. Zhang, S.X. Zhang, H.W. Zhao IMP, Lanzhou, People's Republic of China
	In order to improve the electro-magnetic performance of the quarter wave resonator, a new-shaped cavity with an elliptical cylinder outer conductor has been proposed. This novel cavity design can provide much lower peak surface magnetic field and much higher Ra/Q0 and G. The Multipacting simulation has been done for this new QWR cavity using ACE3P/TRACK3P code, in this paper the simulation results will be presented and analyzed.

TUPB060	Multipacting Suppression Modeling for Half Wave Resonator and RF Coupler*	simulation, cavity, cryomodule, impedance	612
	Z. Zheng, A. Facco, Z. Liu, J. Popielarski, K. Saito, J. Wei, Y. Xu, Y. Zhang FRIB, East Lansing, Michigan, USA Z. Zheng TUB, Beijing, People's Republic of China
	Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661 In prototype cryomodule test of Facility of Rare Isotope Beam (FRIB) β=0.53 half-wave-resonators (HWRs) severe multipacting barriers, prevented RF measurement at the full field specified. The multipacting could not be removed by several hours of RF conditioning. To better understand and to eliminate multipacting, physics models and CST simulations have been developed for both cavity and RF coupler. The simulations have good agreement with the multipacting discovered in coupler and cavity testing. Proposed cavity and coupler geometric optimizations are discussed in this paper.

TUPB066	Reduced-beta Cavities for High-intensity Compact Accelerators	cavity, ion, niobium, heavy-ion	621
	Z.A. Conway, S.M. Gerbick, M. Kedzie, M.P. Kelly, J.W. Morgan, R.C. Murphy, P.N. Ostroumov, T. Reid ANL, Argonne, USA
	Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under contract number DE-AC02-06CH11357 and WFO 8R268. This paper reports on the development and testing of a superconducting quarter-wave and a superconducting half-wave resonator. The quarter-wave resonator is designed for β = 0.077 ions, operates at 72 MHz and can provide more than 7.4 MV of accelerating voltage at the design beta, with peak surface fields of 164 mT and 117 MV/m. Operation was limited to this level not by RF surface defects but by our available RF power and administrative limits on x-ray production. A similar goal is being pursued in the development of a half-wave resonator designed for β = 0.29 ions and operated at 325 MHz.

TUPB073	Design and Simulation of a Test Model for a Tri-Spoke Cavity at RIKEN	cavity, simulation, vacuum, superconducting-cavity	642
	L. Lu RIKEN, Saitama, Japan O. Kamigaito, N. Sakamoto, K. Suda, K. Yamada RIKEN Nishina Center, Wako, Japan
	A design for a tri-spoke-type superconducting cavity for uranium beams with β = 0.303 and a 219 MHz operational frequency is presented. And a test model designed and assembled by two end-wall flanges and one triparted part of the designed tri-spoke cavity, was expected to be built using the same fabrication technology that is supposed for Nb cavity manufacture. The designs and simulations of the tri-spoke cavity and the test model will be reported in this paper.

TUPB079	Design and Beam Test of Six-Electrode BPMs for Second-Order Moment Measurement	factory, multipole, linac, storage-ring	654
	K. Yanagida, H. Hanaki, S. Suzuki JASRI/SPring-8, Hyogo-ken, Japan
	In the SPring-8 linac, four-electrode beam position monitors (BPMs) have been utilized for the measurement of the transverse first-order moments, which correspond to the centroids of beam charge distributions. We have planed to measure the transverse second-order moments of beams to obtain information of beam optics and its energy deviations during the top-up beam injection without destruction of beams. Therefore, six-electrode BPMs with circular and quasi-ellipse cross-sections have been developed on the basis of a newly introduced theory. A low-noise signal processor for the six-electrode BPM has also been developed to perform fine measurement. We expected the following resolutions determined by the S/N ratio of the circuit; the first order moments (beam positions) >1 μm, and the second order moments with a size >110 μm. The first beam test was carried out using the six-electrode BPM with circular cross-section and the old signal processor. The measured sensitivities and resolutions of the second-order moments showed good agreement with the theory.

TUPB080	Non-destructive Real-time Monitor to Measure 3D Bunch Charge Distribution with Arrival Timing to Maximize 3D Overlapping for HHG-Seeded EUV-FEL	FEL, laser, feedback, optics	657
	H. Tomizawa, K. Ogawa, T. Sato, M. Yabashi RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan M. Aoyama JAEA/Kansai, Kyoto, Japan A. Iwasaki, S. Owada The University of Tokyo, Tokyo, Japan S. Matsubara, Y. Okayasu, T. Togashi JASRI/SPring-8, Hyogo, Japan T. Matsukawa, H. Minamide RIKEN ASI, Sendai, Miyagi, Japan E. Takahashi RIKEN, Saitama, Japan
	Non-destructive, shot-by-shot real-time monitors have been developed to measure 3D bunch charge distribution (BCD). This 3D monitor has been developed to monitor 3D overlapping electron bunches and higher harmonic generation (HH) pulses in a seeded VUV-FEL. This ambitious monitor is based on an Electro-Optic (EO) multiple sampling technique in a manner of spectral decoding that is non-destructive and enables real-time measurements of the longitudinal and transverse BCD. This monitor was materialized in simultaneously probing eight EO crystals that surround the electron beam axis with a radial polarized and hollow EO-probe laser pulse. In 2009, the concept of 3D-BCD monitor was verified through electron bunch measurements at SPring-8. The further target of the temporal resolution is ~30 fs (FWHM), utilizing an organic EO crystal (DAST) instead of conventional inorganic EO crystals (ZnTe, GaP, etc.) The EO-sampling with DAST crystal is expected to measure a bunch length less than 30 fs (FWHM). In 2011, the first bunch measurement with an organic EO crystal (DAST) was successfully demonstrated in the VUV-FEL accelerator at SPring-8.

TUPB081	Beam Diagnostics Development for Triumf E-Linac	target, TRIUMF, diagnostics, pick-up	660
	V.A. Verzilov, P.S. Birney, D.P. Cameron, J.V. Holek, S.Y. Kajioka, S. Kellogg, M. Lenckowski, M. Minato, W.R. Rawnsley TRIUMF, Vancouver, Canada J.M. Abernathy, D. Karlen, D.W. Storey Victoria University, Victoria, B.C., Canada
	TRIUMF laboratory is currently in a phase of the construction of a new superconducting 50 MeV 10 mA cw electron linac (e-linac) to drive photo-fission based rare radioactive isotope beam (RIB) production. The project imposes certain technical challenges on various accelerator systems including beam diagnostics. In the first place these are a high beam power and strongly varying operating modes ranging from very short beam pulses to the cw regime. A number of development projects have been started to construct the diagnostics instrumentation required for commissioning and operation of the facility. The paper reports the present status of the projects along with measurement results obtained at the test facility which produced the first beam in Fall of 2011.

WE1A01	ERL-Based Light Source Challenges	gun, linac, laser, emittance	714
	Y. Kobayashi KEK, Ibaraki, Japan
	The challenges of the design and technology for the future Energy Recovery Liancs will be reviewed: electron sources, injector, SCRF cavities and cryomodules, commissioning.

WE1A05	Linac-Based Laser Compton Scattering X-Ray and Gamma-Ray Sources	photon, laser, linac, brightness	734
	R. Hajima JAEA, Ibaraki-ken, Japan
	Laser Compton scattering (LCS) light sources can provide high-energy photons from keV to MeV range. Many research and development projects of linac-based LCS sources are carried on. For the photon energies of tens keV, linac-based LCS sources realize laboratory-size X-ray sources, of which performance can be comparable to synchrotron light sources. Linac-based LCS also realizes unprecedented gamma-ray sources with better monochromaticity than ring-based LCS sources. This talk will review linac-based LCS source in the world.
	Slides WE1A05 [2.881 MB]

TH1A03	Superconducting Spoke Cavities for Electron and High-Velocity Proton Linacs	cavity, linac, impedance, SRF	758
	J.R. Delayen ODU, Norfolk, Virginia, USA
	Spoke resonantors are currently under development for many proton machines but these structures are also considered for high beta electron linacs as well. These structures compare well to traditional elliptical cavities.
	Slides TH1A03 [3.570 MB]

TH2A004	Computational Model Analysis for Experimental Observation of Optical Current Noise Suppression Below the Shot-noise Limit	plasma, linac, simulation, beam-transport	783
	A. Gover University of Tel-Aviv, Faculty of Engineering, Tel-Aviv, Israel A. Nause University of Tel Aviv, Tel Aviv, Israel
	Funding: We acknowledge support of the Israel Science Foundation grant We report first demonstration of optical frequency current shot-noise suppression in a relativistic e-beam. This process is made possible by collective Coulomb interaction between the electrons of a cold intense beam during beam drift, and is essentially a process of longitudinal beam-plasma oscillation.[1] Suppression of beam current noise below the classical “shot-noise” level has been known in the microwave tubes art [2]. This is the first time that it is demonstrated in the optical regime. We predict that the scheme can be extended to the XUV and possibly to shorter wavelengths with further development of technology. The fundamental current shot-noise determines the level of incoherent spontaneous radiation emission from electron-beam optical radiation sources and SASE-FELs [3]. Suppressing shot-noise would make it possible to attain spontaneous emission sub-radiance [4] and surpass the classical coherence limits of seed-injected FELs. The effect was demonstrated by measuring sub-linear growth as a function of current of the OTR Radiation. This finding indicates that the beam charge homogenizes due to the collective interaction, and its distribution becomes sub-Poissonian. [1] A. Gover, E. Dyunin, PRL, 102, 154801, 2009 [2] H. Haus, N. Robinson, Proc. IRE, 43, 981 (1955) [3] P. Emma, et al , Nature Photonics 4, 641 (2010) [4] A. Dicke, Phys. Rev. 93, 99 (1954)

TH3A02	The 12 GeV Energy Upgrade at Jefferson Laboratory	cryomodule, linac, cavity, collider	792
	F.C. Pilat JLAB, Newport News, Virginia, USA
	Two new cryomodules and an extensive upgrade of the bending magnets at Jefferson Lab has been recently completed in preparation for the full energy upgrade in about one year.
	Slides TH3A02 [3.482 MB]

TH3A03	ERL-Based Lepton-Hadron Colliders: eRHIC and LHeC	linac, hadron, ion, proton	797
	F. Zimmermann CERN, Geneva, Switzerland
	This talk will review hadron-ERL collider projects. The LHeC is a plan to collide the LHC beam with electrons or positrons. One scheme for this facility is based on a superconducting recirculating linac with energy recovery. The electron hadron collider eRHIC will collide polarized and unpolarized electrons with a current of 50 mA and energy in the range of 5 GeV to 30 GeV with hadron beams, including heavy ions or polarized light ions of the RHIC storage ring. The electron beam will be generated in an energy recovery linac contained inside the RHIC tunnel, comprising six passes through two linac section of about 2.5 GeV each.
	Slides TH3A03 [3.286 MB]

TH3A04	Plasmas, Dielectrics and the Ultrafast: First Science and Operational Experience at FACET	plasma, radiation, linac, acceleration	802
	C.I. Clarke, E. Adli, S. Corde, F.-J. Decker, R.J. England, R.A. Erickson, A.S. Fisher, S.J. Gessner, C. Hast, M.J. Hogan, S.Z. Li, N. Lipkowitz, M.D. Litos, Y. Nosochkov, J.T. Seeman, J. Sheppard, I. Tudosa, G.R. White, U. Wienands, M. Woodley, Z. Wu, G. Yocky SLAC, Menlo Park, California, USA C.E. Clayton, C. Joshi, W. Lu, K.A. Marsh, N. Vafaei UCLA, Los Angeles, California, USA
	Funding: Work supported by the U.S. Department of Energy under contract number DE-AC02-76SF00515. FACET (Facility for Advanced Accelerator and Experimental Tests) is an accelerator R&D test facility that has been recently constructed at SLAC National Accelerator Laboratory. The facility provides 20 GeV, 3 nC electron beams, short (20 um) bunches and small (20 um wide) spot sizes, producing uniquely high power beams. FACET supports studies from many fields but in particular those of Plasma Wakefield Acceleration and Dielectric Wakefield Acceleration. FACET is also a source of THz radiation for material studies. We present the FACET design, initial operating experience and first science from the facility.
	Slides TH3A04 [3.091 MB]

THPLB11	Experimental and Simulation Study of the Long-path-length Dynamics of a Space-charge-dominated Bunch	simulation, space-charge, emittance, focusing	834
	I. Haber, B.L. Beaudoin, S. Bernal, R.A. Kishek, T.W. Koeth, Y. Mo UMD, College Park, Maryland, USA
	Funding: Work supported by the United States Department of Energy and the Office of Naval Research. The University of Maryland Electron Ring (UMER) is a low-energy (10 keV) electron facility built to study, on a scaled machine, the long-propagation-length evolution of a space-charge-dominated beam. Though constructed in a ring geometry to achieve a long path length at modest cost, UMER has observed important space-charge physics directly relevant to linear machines. Examples will be presented that emphasize studies of the longitudinal dynamics and comparisons to axisymmetric simulations. The detailed agreement obtained between simulation and experiment will be presented as evidence that the longitudinal physics observed is not strongly influenced by the ring geometry. Novel phenomena such as soliton formation, unimpeded bunch-end interpenetration, and an instability that occurs after this interpenetration, will be discussed.

THPB061	Experimental and Simulation Study of the Long-path-length Dynamics of a Space-charge-dominated Bunch	simulation, space-charge, emittance, focusing	978
	I. Haber, B.L. Beaudoin, S. Bernal, R.A. Kishek, T.W. Koeth, Y. Mo UMD, College Park, Maryland, USA
	Funding: Work supported by the United States Department of Energy and the Office of Naval Research. The University of Maryland Electron Ring (UMER) is a low-energy (10 keV) electron facility built to study, on a scaled machine, the long-propagation-length evolution of a space-charge-dominated beam. Though constructed in a ring geometry to achieve a long path length at modest cost, UMER has observed important space-charge physics directly relevant to linear machines. Examples will be presented that emphasize studies of the longitudinal dynamics and comparisons to axisymmetric simulations. The detailed agreement obtained between simulation and experiment will be presented as evidence that the longitudinal physics observed is not strongly influenced by the ring geometry. Novel phenomena such as soliton formation, unimpeded bunch-end interpenetration, and an instability that occurs after this interpenetration, will be discussed.

THPB063	Simulated Performance of the CARIBU EBIS Charge Breeder Transport Line	ion, simulation, emittance, diagnostics	984
	C. Dickerson, S.A. Kondrashev, B. Mustapha, P.N. Ostroumov ANL, Argonne, USA
	Funding: This work is supported by the U.S. Department of Energy, Office of Nuclear Physics, under contract number DE-AC02-06CH11357. An Electron Beam Ion Source (EBIS) has been designed and is being built to charge breed ions from the CAlifornium Rare Isotope Breeder Upgrade (CARIBU) for post acceleration in the Argonne Tandem Linear Accelerator System (ATLAS). The calculated transverse acceptance of the EBIS charge breeder can approach the emittance of the injected ion beam, so beam distortion during transport could lead to incomplete injection and a decrease in the overall system efficiency. The beam quality can be maintained for simulations of the transport line using the ideal ion beam parameters. This paper reports the results of the electrostatic and ion beam transport simulations used to minimize the ion beam distortions by optimizing component designs and configurations.

THPB064	Beam Dynamics Tools for Linacs Design	simulation, beam-loading, linac, synchrotron	987
	A.S. Setty THALES, Colombes, France
	In the last 25 years, we have been using our in house 3D code PRODYN * for electron beam simulations. We have also been using our in house code SECTION for the design of the travelling wave accelerating structures and the beam loading compensation. PRODYN follows in time, the most complicated electron trajectories with relativistic space-charge effects. This code includes backward as well as forwards movements. This paper will describe those two codes and will give some simulations and measurements results. * D. Tronc and A. Setty, Electrons RF auto-focusing and capture in bunchers, Linear Accelerator Conference 1988, Virginia.

THPB074	RF Photoinjector and Radiating Structure for High-power THz Radiation Source	radiation, coupling, vacuum, impedance	1005
	S.M. Polozov, T.V. Bondarenko MEPhI, Moscow, Russia Y.A. Bashmakov LPI, Moscow, Russia
	Sources of high-power electromagnetic radiation in THz band are becoming promising as a new method of a low activation introscopy. Research and development of accelerating RF photoinjector and radiating system for THz radiation source are reported. The photoinjector is based on disk loaded waveguide (DLW). Two different designs of accelerating structures were modeled: widespread 1.6 cell of DLW structure and travelling wave resonator structure. The resonant models of these structures and the structures with power ports were designed. Electrodynamics characteristics and electric field distribution for all models were acquired. Results of picoseconds photoelectron beam dynamics in modeled structures are reported. Design of decelerating structures exciting Cherenkov radiation are based on corrugated metal channel and metal channel coated with dielectric. Analysis of radiation intensity and frequency band are presented.

THPB089	Magnetic Characterization of the Phase Shifter Prototypes Built by CIEMAT for E-XFEL	undulator, free-electron-laser, laser, FEL	1029
	I. Moya, J. Calero, J.M. Cela-Ruiz, L. García-Tabarés, A. Guirao, J.L. Gutiérrez, L.M. Martinez, T. Martínez de Alvaro, E. Molina Marinas, L. Sanchez, S. Sanz, F. Toral, C. Vázquez, J.G.S. de la Gama CIEMAT, Madrid, Spain J. Campmany, J. Marcos, V. Massana CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain
	Funding: Work partially supported by Spanish Ministry of Science and Innovation under SEI Resolution on 17-September-2009 and project ref. AIC-2010-A-000524 The European X-ray Free Electron Laser (E-XFEL) will be based on a 10 to 17.5 GeV electron linac that will be used in the undulator system to obtain ultra-brilliant X-ray flashes from 0.1 to 6 nanometres for experimentation. The undulator system is formed by undulators and intersections between them, where a quadrupole on top of a precision mover, a beam position monitor, two air coils and a phase shifter are allocated. The function of the phase shifter is to adjust the phase of the electron beam and the radiation when they enter in an undulator according to the different beam energies and wavelengths. CIEMAT is working on the development of the phase shifters, as part of the Spanish in-kind contribution to the E-XFEL project. Several problems reported elsewhere were detected in the first prototype, which did not fulfil the first field integral specification. This paper describes the magnetic measurements realized on the second and third prototypes in the test bench at CELLS, together with the tuning process to decrease the field integral dependence with gap.

THPB092	Recent Improvements in SPring-8 Linac for Early Recovery from Beam Interruption	klystron, gun, linac, power-supply	1035
	S. Suzuki, T. Asaka, H. Dewa, H. Hanaki, T. Kobayashi, T. Magome, A. Mizuno, T. Taniuchi, H. Tomizawa, K. Yanagida JASRI/SPring-8, Hyogo-ken, Japan
	The 1GeV SPring-8 linac is an injector for the SPring-8 synchrotron radiation storage ring with 8GeV booster synchrotron. In recent years, backup systems were installed to eliminate long-time interruption of the beam injections: The main gun system is usually operated, and the second gun is always pre-heated and can inject electron beams into a buncher section with an interval of several minutes in case the main gun failed. The first klystron, that feeds RF powers to the buncher system and the downstream klystrons, can be relieved by the next klystron with an interval of about 20 minutes by switching the waveguide circuit. When one of the eleven working klystrons faults, one of standby klystrons, which are kept for hot spares on line, is automatically activated to accelerate beams instead of the failed one without beam interruption. The total downtime in FY2012 was 0.12% in top-up operation user time. The averaged fault frequency was 0.2 times per day.

THPB095	Designing of a Phase-mask-type Laser Driven Dielectric Accelerator for Radiobiology	laser, acceleration, simulation, vacuum	1041
	K. Koyama UTNL, Ibaraki, Japan A. Aimidura, M. Uesaka The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan Y. Matsumura University of Tokyo, Tokyo, Japan T. Natsui, M. Yoshida KEK, Ibaraki, Japan
	Funding: This work is supported by KAKENHI, Grant-in-Aid for Scientific Research (C) 24510120 In order to estimate the health risk of a low radiation dose, basic processes of the radiobiology should be clarified by shooting a DNA using a spatially and temporary defined particle beam or X-ray. A suitable beam size is as small as a resolving power of an optical microscope of a few hundred nanometers. Photonic crystal accelerators (PCA) are capable of delivering nm-beams of sub-fs pulses because the characteristic length and frequency of PCAs are on the order of the laser light. Since the phase-mask type accelerator has a simpler structure than other types of PCAs, we are designing a phase-mask type laser driven dielectric accelerator. By adopting an unbalanced length of pillar and ditch (grating) of 4:1, a standing wave like acceleration field is produced in a acceleration channel. A pillar height and initial speed of injected electron are determined by analytically. The maximum acceleration gradient of 2 GeV/m is estimated. The required laser power is roughly estimated to be 6.5 GW. The simulation using CST-code also shows similar values to accelerate electrons by the phase-mask type accelerator.

THPB096	High-power Sources of RF Radiation Driven by Periodic Laser Pulses	laser, cavity, radiation, klystron	1044
	S.V. Kuzikov, A.V. Savilov IAP/RAS, Nizhny Novgorod, Russia S.V. Kuzikov Omega-P, Inc., New Haven, USA
	Funding: Supported in part by DoE USA. A fast, periodic modulation of electron RF sources can be carried out in a form of Q-factor switching by means of fast RF switches, or in a form of I-switching by means of the bunched electron beam. If modulation frequency equals to time which is necessary for RF radiation to travel along the cavity and to come back, the RF oscillator can produce periodic, giant, short pulses which are desirable for many applications in order to avoid a breakdown. The produced RF pulses are phase and frequency locked by modulation shape. The mentioned effects of the phase and frequency locking remain also possible for RF sources operated in a single-mode regime. In last case the modulation frequency should be close to natural single-mode oscillation frequency. For example, one might control operation of a BWO by means of a small periodical modulation of the electron voltage in a drift section in-between a cathode and the corrugated interaction section. The necessary voltage modulation can be provided by means of a DC generator those voltage due to a photoconductivity is externally modulated with definite frequency by laser which irradiates GaAs isolator inserted in-between the electrodes.

FR1A01	Heavy Ion Strippers	ion, plasma, heavy-ion, cyclotron	1050
	F. Marti FRIB, East Lansing, Michigan, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661 Stripping of high current heavy ion beams is a key technology for future accelerator as FAIR (Germany) and FRIB (USA) and current ones as RIBF (RIKEN, Japan). A small change in the peak charge state produced at the stripper could require a significant expense in additional accelerating stages to obtain the required final energy. The main challenges are the thermal effects due to the high power deposition (~ 50 kW/mm³) and the radiation damage due to the high energy deposition. The effects of heavy ion beams are quite different from proton beams because of the much shorter range in matter. We will present an overview talk considering charge stripping devices like carbon foils and gas cells used worldwide as well as the current research efforts on plasma stripping, liquid metal strippers, etc. The advantages and disadvantages of the different options will be presented.
	Slides FR1A01 [4.174 MB]

Paper

Title

Other Keywords

Page

SUPB009

Linear Accelerator based on Parallel Coupled Accelerating Structure

cavity, controls, focusing, klystron

19

A.E. Levichev, A.M. Barnyakov, V.M. Pavlov
BINP SB RAS, Novosibirsk, Russia
Y.D. Chernousov
ICKC, Novosibirsk, Russia
V. Ivannikov, I.V. Shebolaev
ICKC SB RAS, Novosibirsk, Russia

Accelerating stand based on parallel coupled accelerating structure and electron gun is developed and produced. The structure consists of five accelerating cavities. The RF power feeding of accelerating cavities is provided by common exciting cavity which is performed from rectangular waveguide loaded by reactive pins. Operating frequency is 2450 MHz. Electron gun is made on the basis of RF triode. Linear accelerator was tested with different working regimes. The obtained results are following: energy is up to 4 MeV, accelerating current is up to 300 mA with pulse duration of 2.5 ns on the half of the width; energy is up to 2.5 MeV, accelerating current is up to 100 mA with pulse duration of 5 μs; energy is up to 2.5 MeV, accelerating current is up to 120 mA with pulse duration of 5 μs and beam capture of 100%. The descriptions of the accelerator elements are given in the report. The features of the parallel coupled accelerating structure are discussed. The results of the measuring accelerator’s parameters are presented.

SUPB010

Measurements of a Reduced Energy Spread of a Recirculating Linac by Non-Isochronous Beam Dynamics

recirculation, linac, synchrotron, acceleration

22

F. Hug, C. Burandt, M. Konrad, N. Pietralla
TU Darmstadt, Darmstadt, Germany
R. Eichhorn
Cornell University, Ithaca, New York, USA

Funding: supported by DFG through SFB 634
The Superconducting Linear Accelerator S-DALINAC at the University of Darmstadt (Germany) is a recirculating linac with two recirculations providing beams for measurements in nuclear physics at small momentum transfers. For these experiments an energy spread of better than 10^-4 (rms) is needed. Currently acceleration in the linac section is done on crest of the accelerating field. The recirculation path is operated achromatic and isochronous. In this recirculation scheme the energy spread of the resulting beam in the ideal case is determined by the electron bunch length. Taking into account the stability of the RF system the energy spread increases drastically to more than 10^-3 (rms). We will present a new non-isochronous recirculation scheme which helps cancelling out these errors from the rf-control. This scheme uses longitudinal dispersion in the recirculation paths and an acceleration off-crest with a certain phase with respect to the maximum. We will present results of the commissioning of the new system including measurements of the longitudinal dispersion in the recirculation arcs as well as measurements of the resulting energy spread using an electron spectrometer.

SUPB011

Computational Model Analysis for Experimental Observation of Optical Current Noise Suppression Below the Shot-noise Limit

plasma, linac, simulation, beam-transport

25

A. Nause, A. Gover
University of Tel-Aviv, Faculty of Engineering, Tel-Aviv, Israel

Funding: We acknowledge support of the Israel Science Foundation grant
We report first demonstration of optical frequency current shot-noise suppression in a relativistic e-beam. This process is made possible by collective Coulomb interaction between the electrons of a cold intense beam during beam drift, and is essentially a process of longitudinal beam-plasma oscillation [1]. Suppression of beam current noise below the classical “shot-noise” level has been known in the microwave tubes art [2]. This is the first time that it is demonstrated in the optical regime. We predict that the scheme can be extended to the XUV and possibly to shorter wavelengths with further development of technology. The fundamental current shot-noise determines the level of incoherent spontaneous radiation emission from electron-beam optical radiation sources and SASE-FELs [3]. Suppressing shot-noise would make it possible to attain spontaneous emission sub-radiance [4] and surpass the classical coherence limits of seed-injected FELs. The effect was demonstrated by measuring sub-linear growth as a function of current of the OTR Radiation. This finding indicates that the beam charge homogenizes due to the collective interaction, and its distribution becomes sub-Poissonian.
[1] A. Gover, E. Dyunin, PRL, 102, 154801, 2009
[2] H. Haus, N. Robinson, Proc. IRE, 43, 981 (1955)
[3] P. Emma, et al , Nature Photonics 4, 641 (2010)
[4] A. Dicke, Phys. Rev. 93, 99 (1954)

SUPB019

The Multipacting Simulation for the New-Shaped QWR using TRACK3P

cavity, simulation, accelerating-gradient, niobium

50

C. Zhang, S. He, Y. He, S.C. Huang, Y.L. Huang, T.C. Jiang, R.X. Wang, M.X. Xu, Y.Z. Yang, W.M. Yue, S.H. Zhang, S.X. Zhang, H.W. Zhao
IMP, Lanzhou, People's Republic of China

In order to improve the electro-magnetic performance of the quarter wave resonator, a new-shaped cavity with an elliptical cylinder outer conductor has been proposed. This novel cavity design can provide much lower peak surface magnetic field and much higher Ra/Q0 and G. The Multipacting simulation has been done for this new QWR cavity using ACE3P/TRACK3P code, in this paper the simulation results will be presented and analyzed.

SUPB026

Multipacting Analysis of High-velocity Superconducting Spoke Resonators

cavity, site, simulation, superconductivity

68

C.S. Hopper, J.R. Delayen
ODU, Norfolk, Virginia, USA

Some of the advantages of superconducting spoke cavities are currently being investigated for the high-velocity regime. When determining a final, optimized geometry, one must consider the possible limiting effects multipacting could have on the cavity. We report on the results of analytical calculations and numerical simulations of multipacting electrons in superconducting spoke cavities and methods for reducing their impact.

SUPB035

RF Photoinjector and Radiating Structure for High-power THz Radiation Source

radiation, coupling, vacuum, impedance

86

S.M. Polozov, T.V. Bondarenko
MEPhI, Moscow, Russia
Y.A. Bashmakov
LPI, Moscow, Russia

Sources of high-power electromagnetic radiation in THz band are becoming promising as a new method of a low activation introscopy. Research and development of accelerating RF photoinjector and radiating system for THz radiation source are reported. The photoinjector is based on disk loaded waveguide (DLW). Two different designs of accelerating structures were modeled: widespread 1.6 cell of DLW structure and travelling wave resonator structure. The resonant models of these structures and the structures with power ports were designed. Electrodynamics characteristics and electric field distribution for all models were acquired. Results of picoseconds photoelectron beam dynamics in modeled structures are reported. Design of decelerating structures exciting Cherenkov radiation are based on corrugated metal channel and metal channel coated with dielectric. Analysis of radiation intensity and frequency band are presented.

MO1A02

Status of the European XFEL – Constructing the 17.5 GeV Superconducting Linear Accelerator

cavity, undulator, photon, klystron

105

W. Decking
DESY, Hamburg, Germany

The European XFEL is presently under construction in Hamburg, Germany. It consists of a 1.2 km long superconducting linac serving an about 3 km long electron beam transport system. Three undulator systems of up to 200 m length each produce hard and soft x-rays via the self-amplified spontaneous emission (SASE) process. We will present the status of the civil construction and the accelerator components. The production of the 100 superconducting accelerator modules is distributed between industries and a collaboration of accelerator laboratories. We describe the carefully orchestrated production sequence, quality assurance measures and risk mitigation mechanisms. The last module is scheduled to be installed in the accelerator in spring 2015 and commissioning with beam will start in summer of that year.

Slides MO1A02 [8.730 MB]

MOPLB02

Positron Injector Linac Upgrade for SuperKEKB

positron, linac, quadrupole, target

141

T. Kamitani, M. Akemoto, D.A. Arakawa, Y. Arakida, A. Enomoto, S. Fukuda, K. Furukawa, Y. Higashi, T. Higo, H. Honma, N. Iida, M. Ikeda, E. Kadokura, K. Kakihara, H. Katagiri, M. Kurashina, S. Matsumoto, T. Matsumoto, H. Matsushita, S. Michizono, K. Mikawa, T. Miura, F. Miyahara, T. Mori, H. Nakajima, K. Nakao, T. Natsui, Y. Ogawa, S. Ohsawa, M. Satoh, T. Shidara, A. Shirakawa, H. Sugimoto, T. Suwada, T. Takatomi, T. Takenaka, Y. Yano, K. Yokoyama, M. Yoshida, L. Zang, X. Zhou
KEK, Ibaraki, Japan
D. Satoh
TIT, Tokyo, Japan

The KEKB B-factory is under an upgrade construction for the SuperKEKB. To achieve 40 times higher luminosity, the linac is required to inject electrons and positrons with higher intensities (e^-: 1 nC → 5 nC, e⁺: 1 nC → 4 nC) and lower emittances (e^-: 300 → 20 μm, e⁺: 2100 → 10 μm). This paper describes the upgrade scheme of the positron source. A new positron capture section will have larger transverse and energy acceptances by introducing a flux concentrator and large aperture L-band and S-band accelerating structures. Beam line layout and quadrupole focusing system will be rearranged for the enlarged beam acceptance. Beam optics is designed to be compatible for positron and electron beams with different energies and emittances. Pulsed quadrupoles and steering magnets are added for better flexibility in optics and orbit tuning. Parameter optimization of the positron source by optics calculation and particle tracking simulation is described.

Slides MOPLB02 [0.575 MB]

MOPLB03

Advances in Beam Tests of Dielectric Based Accelerating Structures

wakefield, acceleration, laser, linac

144

A. Kanareykin, S.P. Antipov, J.E. Butler, C.-J. Jing
Euclid TechLabs, LLC, Solon, Ohio, USA
W. Gai
ANL, Argonne, USA
V. Yakimenko
BNL, Upton, Long Island, New York, USA

Funding: US Department of Energy
Diamond is being evaluated as a dielectric material for dielectric loaded accelerating structures. It has a very low microwave loss tangent, high thermal conductivity, and supports high RF breakdown fields. We report on progress in our recent beam tests of the diamond based accelerating structures of the Ka-band and THz frequency ranges. Wakefield breakdown test of a diamond-loaded accelerating structure has been carried out at the ANL/AWA accelerator. The high charge beam from the AWA linac (~70 nC, σ_z = 2.5 mm) was passed through a rectangular diamond loaded resonator and induce an intense wakefield. A groove is cut on the diamond to enhance the field. Electric fields up to 0.3 GV/m has been detected on the diamond surface to attempt to initiate breakdown. A surface analysis of the diamond has been performed before and after the beam test. Wakefield effects in a 250 GHz planar diamond accelerating structure has been observed at BNL/ATF accelerator as well. We have directly measured the mm-wave wake fields induced by subpicosecond, intense relativistic electron bunches in a diamond loaded accelerating structure via the dielectric wake-field acceleration mechanism.

Slides MOPLB03 [1.986 MB]

MOPLB04

A 10 MeV L-band Linac for Irradiation Applications in China

linac, gun, klystron, simulation

147

G. Pei, Y.L. Chi, M.H. Dai, D.Y. He, X. He, X. Li, J. Liu, C. Ma, X. Wang, C.H. Yu, F. Zhao, J. Zhao, Z.S. Zhou
IHEP, Beijing, People's Republic of China
Y. Feng, H. Huang, S. Shi, E. Tang, X. Yang, Q. Yuan, Z. Zhu
Institute of High Energy Physics (IHEP), People's Republic of China
Z. Li, X. Zhang
Wuxi EL PONT Radiation Technology Ltd, Wuxi, People's Republic of China

The electron linear accelerator has wide applications, and the demands are keeping growing for the irradiation applications in China. A high beam power 10 MeV L-band Linac has been developed recently as a joint venture of Institute of High Energy Physics and EL-PONT Company. The Thales TH2104U klystron, 3 A thermionic electron gun and three meter L-band disk-loaded constant impedance RF structure are adopted. A stable electron beam of 10 MeV, 40 kW has been obtained in the last May with a microwave to beam efficiency of about 65%. In this paper we will present the detailed design issues and beam commissioning.

Slides MOPLB04 [1.800 MB]

MOPLB05

Applications of Compact Dielectric-Based Accelerators

coupling, multipactoring, wakefield, impedance

150

C.-J. Jing, S.P. Antipov, A. Kanareykin, P. Schoessow
Euclid TechLabs, LLC, Solon, Ohio, USA
M.E. Conde, W. Gai, J.G. Power
ANL, Argonne, USA

Important progress on the development of dielectric based accelerators has been made experimentally and theoretically in the past few years. One advantage of dielectric accelerators over the metallic counterparts is its compact size, which may attract some applications in industrial or medical accelerators. In this article, we discuss the design and technologies of dielectric based accelerators toward these needs.

MOPLB08

Normal Conducting Deflecting Cavity Development at the Cockcroft Institute

cavity, beam-loading, wakefield, damping

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

klystron, coupling, controls, FEL

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]

MOPLB11

The Upgraded Argonne Wakefield Accelerator Facility (AWA): a Test-Bed for the Development of High Gradient Accelerating Structures and Wakefield Measurements

wakefield, gun, linac, acceleration

168

M.E. Conde, D.S. Doran, W. Gai, R. Konecny, W. Liu, J.G. Power, Z.M. Yusof
ANL, Argonne, USA
S.P. Antipov, C.-J. Jing
Euclid TechLabs, LLC, Solon, Ohio, USA
E.E. Wisniewski
Illinois Institute of Technology, Chicago, Illinois, USA

Funding: Work supported by the U.S. Department of Energy under contract No. DE-AC02-06CH11357.
Electron beam driven wakefield acceleration is a bona fide path to reach high gradient acceleration of electrons and positrons. With the goal of demonstrating the feasibility of this concept with realistic parameters, well beyond a proof-of-principle scenario, the AWA Facility is currently undergoing a major upgrade that will enable it to achieve accelerating gradients of hundreds of MV/m and energy gains on the order of 100 MeV per structure. A key aspect of the studies and experiments carried out at the AWA facility is the use of relatively short RF pulses (15 – 25 ns), which is believed to mitigate the risk of breakdown and structure damage. The upgraded facility will utilize long trains of high charge electron bunches to drive wakefields in the microwave range of frequencies (8 to 26 GHz), generating RF pulses with GW power levels.

Slides MOPLB11 [0.900 MB]

MOPLB12

X-Ray Local Energy Spectrum Measurement on Tsinghua Thomson Scattering X-Ray Source (TTX)

scattering, simulation, laser, photon

171

Y.-C. Du, J.F. Hua, W.-H. Huang, C.-X. Tang, L.X. Yan, H. Zha, Z. Zhang
TUB, Beijing, People's Republic of China

Thomson scattering X-ray source, in which the TW laser pulse is scattered by the relativistic electron beam, can provide ultra short, monochromatic, high flux, tunable polarized hard X-ray pulse which is can widely used in physical, chemical and biological process research, ultra-fast phase contrast imaging, and so on. Since the pulse duration of X-ray is as short as picosecond and the flux in one pulse is high, it is difficult to measure the x-ray spectrum. In this paper, we present the X-ray spectrum measurement experiment on Tsinghua Thomson scattering. The preliminary experimental results shows the maximum X-ray energy is about 47 keV, which is agree well with the simulations.

Slides MOPLB12 [1.311 MB]

MOPB002

Positron Injector Linac Upgrade for SuperKEKB

positron, linac, quadrupole, target

177

T. Kamitani, M. Akemoto, D.A. Arakawa, Y. Arakida, A. Enomoto, S. Fukuda, K. Furukawa, Y. Higashi, T. Higo, H. Honma, N. Iida, M. Ikeda, E. Kadokura, K. Kakihara, H. Katagiri, M. Kurashina, S. Matsumoto, T. Matsumoto, H. Matsushita, S. Michizono, K. Mikawa, T. Miura, F. Miyahara, T. Mori, K. Nakao, T. Natsui, Y. Ogawa, S. Ohsawa, T. Shidara, A. Shirakawa, H. Sugimoto, T. Suwada, T. Takatomi, T. Takenaka, Y. Yano, K. Yokoyama, M. Yoshida, L. Zang, X. Zhou
KEK, Ibaraki, Japan
D. Satoh
TIT, Tokyo, Japan

The KEKB B-factory is under an upgrade construction for the SuperKEKB. To achieve 40 times higher luminosity, the linac is required to inject electrons and positrons with higher intensities (e^-: 1 nC → 5 nC, e⁺: 1 nC → 4 nC) and lower emittances (e^-: 300 → 20 μm, e⁺: 2100 → 10 μm). This paper describes the upgrade scheme of the positron source. A new positron capture section will have larger transverse and energy acceptances by introducing a flux concentrator and large aperture L-band and S-band accelerating structures. Beam line layout and quadrupole focusing system will be rearranged for the enlarged beam acceptance. Beam optics is designed to be compatible for positron and electron beams with different energies and emittances. Pulsed quadrupoles and steering magnets are added for better flexibility in optics and orbit tuning. Parameter optimization of the positron source by optics calculation and particle tracking simulation is described.

MOPB004

Design and Operation of a Compact 1 MeV X-band Linac

cavity, linac, gun, target

183

G. Burt, T.N. Abram, P.K. Ambattu, C. Lingwood
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
I. Burrows, T. Hartnett, J.P. Hindley, C.J. White
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
P.A. Corlett, A.R. Goulden, P.A. McIntosh, K.J. Middleman, Y.M. Saveliev, R.J. Smith
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

A compact 1 MeV linac has been produced at the Cockcroft Institute using X-band RF technology. The linac is powered by a high power X-band magnetron and has a 17 keV 200 mA thermionic gun with a focus electrode for pulsing. A bi-periodic structure with on-axis coupling is used to minimise the radial size of the linac and to reduce the surface electric fields.

MOPB005

High Gradient Operation of 8 GeV C-Band Accelerator in SACLA

acceleration, laser, klystron, free-electron-laser

186

T. Inagaki, C. Kondo, Y. Otake, T. Sakurai
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan

SACLA (SPring-8 angstrom compact free electron laser) is the X-ray free electron laser (XFEL) facility. In order to shorten the 8 GeV accelerator length, a C-band (5712 MHz) accelerator was employed. Since the accelerating gradient of C-band accelerating structure is 35 MV/m in nominal, the active accelerator length is 230 m. In total, 64 klystrons, 64 pulse compressors, and 128 accelerating structures are used. In order to withstand the high surface field (~ 100 MV/m), and to reduce the amount of dark current, which decreases the demagnetization effect of undulators, the accelerating structures are carefully fabricated in the factory.　After high power RF conditioning of 500 hours, the beam commissioning was started in February 2011. For night time of the commissioning, we continued the RF conditioning. The RF breakdown rate of the structure was steadily decreased. Now we operate the accelerator with the beam energy as much as 8.3 GeV, and the accelerating gradient of 37 MV/m in average. We found the amount of dark current is small enough. So far no trouble occurred in C-band RF components of 64 sets.

MOPB007

Study of Microbunching Instabilitity in the Linac of the Shanghai Soft X-Ray Free Electron Laser Facility

linac, impedance, FEL, simulation

189

D. Huang, Q. Gu, M. Zhang
SINAP, Shanghai, People's Republic of China

The microbunching instability in the LINAC of a FEL facility has always been an issue which may degrade the quality of the electron beam. As the result, the whole facility may not be working properly. Shanghai soft X-ray FEL project (SXFEL), which is planned to start construction by the end of 2012, will be the first X-ray FEL facility in China. In this article, detailed study will be given based on the physical design of the facility to gain better understanding and control over the possible microbunching instability in SXFEL, which is critical to the success of the project. Moreover, the contribution of the possible plasma effects to the instability will also be studied by modifying the physical model of the longitudinal space charge (LSC) impedance.

MOPB011

Photoinjector of the EBTF/CLARA Facility at Daresbury

gun, laser, cavity, vacuum

192

B.L. Militsyn, D. Angal-Kalinin, C. Hill, S.P. Jamison, J.K. Jones, J.W. McKenzie, K.J. Middleman, B.J.A. Shepherd, R.J. Smith, R. Valizadeh, A.E. Wheelhouse
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
N. Bliss, M.D. Roper
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom

A description is given of a photoinjector designed for Compact Linear Advanced Research Accelerator (CLARA) and Electron Beam Test Facility (EBTF), which will eventually be used to drive a compact FEL. The photoinjector is based on a 2.5 cell S-band photocathode RF gun operating with a copper photocathode and driven by a third harmonic of Ti: Sapphire laser (266 nm) installed in dedicated thermally stabilized room. The injector will be operated with laser pulses with an energy of up to 2 mJ, a pulse duration of 100 fs and initially a repetition rate of 10 Hz, with the aim of increasing this eventually to 400 Hz. At a field gradient of 100 MV/m provided by a 10 MW klystron the gun is expected to deliver beam pulses with energy of up to 6 MeV. Duration and emittance of electron bunches essentially depend on the bunch charge and vary from 0.1 ps at 20 pC to 5 ps at 200 pC and from 0.2 to 2 mm mrad respectively. Additional compression of the electron bunches will be provided with a velocity bunching scheme. For thermal stability the low energy part of the injector is mounted on an artificial granite support.

MOPB013

Experimental Results on the PHIL Photo-injector Test Stand at LAL

cathode, emittance, laser, gun

198

R. Roux, F. Blot, J. Brossard, C. Bruni, S. Cavalier, J-N. Cayla, V. Chaumat, M. El Khaldi, A. Gonnin, P. Lepercq, E.N. Mandag, B. Mercier, H. Monard, C. Prevost, V. Soskov, A. Variola
LAL, Orsay, France

Since the first beam in November 2009 of the alphaX S-band RF gun, upgrades of the beamline have been carried out. Several YAG screens based transverse dimensions monitors have been installed as well as supplementary charge diagnostics. We will present a detailed experimental characterization of the RF gun performances such as emittance measurement using a solenoid scan and energy spread as a function of the RF phase. Most of the accelerator operation and experimental results have been carried out with a copper photo-cathode. PHIL being a test stand for photo-injectors, we have also tested a magnesium photo-cathode with the aim of higher charge per bunch thanks to its higher quantum efficiency. We will report on the results of this experiment. In May 2012, a new RF gun, the PHIN gun, will be installed. This gun which is also a S-band 2,5 cells is a copy of the one that LAL built for the CLIC Test Facility 3 at CERN. In the future, we plan to use this gun to produce a high charge up to 10nC with CsTe photo-cathodes introduced in the gun from a UHV transfer chamber. Preliminary tests and measurements of the beam produced by this gun with a copper photo-cathode will be presented.

MOPB014

Electron Model of a Dogbone RLA with Multi-Pass Arcs

linac, quadrupole, dipole, optics

201

S.A. Bogacz, G.A. Krafft, V.S. Morozov, Y. Roblin
JLAB, Newport News, Virginia, USA
K.B. Beard
Muons. Inc., USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Supported in part by USDOE STTR Grant DE-FG02-08ER86351
The design of a dogbone RLA with linear-field multi-pass arcs was earlier developed for accelerating muons in a Neutrino Factory and a Muon Collider. It allows for efficient use of expensive RF while the multi-pass arc design based on linear combined-function magnets exhibits a number of advantages over separate-arc or pulsed-arc designs. Such an RLA may have applications going beyond muon acceleration. This paper describes a possible straightforward test of this concept by scaling a GeV scale muon design for electrons. Scaling muon momenta by the muon-to-electron mass ratio leads to a scheme, in which a 4.35 MeV/c electron beam is injected in the middle of a 2.9 MeV/pass linac with two double-pass return arcs and is accelerated to 17.4 MeV/c in 4.5 passes. All spatial dimensions including the orbit distortion are scaled by a factor of 7.5, which arises from scaling the 200 MHz muon RF to a readily available 1.5 GHz. The footprint of a complete RLA fits in a 25x7 m area. The scheme utilizes only fixed field magnets for both injection and extraction. The hardware requirements are not very demanding making it straightforward to implement the scaled design using available equipment.

MOPB023

Progress on the Design and Construction of the 100 MeV / 100 kW Electron Linac for the NSC KIPT Neutron Source

linac, klystron, gun, neutron

222

S. Pei, J. Cao, Y.L. Chi, B. Deng, C.D. Deng, H.S. Guo, D.Y. He, X. He, M. Hou, X.C. Kong, Q. Le, X. Li, J. Liu, R.L. Liu, W.B. Liu, K. Lv, C. Ma, H.Z. Ma, G. Pei, H. Song, L. Wang, S.H. Wang, X. Wang, Q. Yang, J. Yue, J.R. Zhang, F. Zhao, J.B. Zhao, J.X. Zhao, Z.S. Zhou
IHEP, Beijing, People's Republic of China
M.I. Ayzatskiy, I.M. Karnaukhov, V.A. Kushnir, V.V. Mytrochenko, A.Y. Zelinsky
NSC/KIPT, Kharkov, Ukraine
Y. Gohar
ANL, Argonne, USA

IHEP in China is designing and constructing a 100 MeV / 100 kW electron linac for NSC KIPT, which will be used as the driver of a neutron source based on a subcritical assembly. Recently, the physical design has been finalized. The chicane scheme instead of the RF chopper one has been selected. The mechanical design is on-going and will be finished in the very near future. The injector part of the machine has been installed in the experimental hall #2 of IHEP and is being commissioned and tested. The progress on the machine design and construction are reported, initial testing and commissioning results of the injector are also presented.
*peisl@ihep.ac.cn

MOPB024

Beam Dynamics Simulation and Optimization for 10 MeV Superconducting e-Linac Injector for VECC-RIB Facility

linac, TRIUMF, gun, emittance

225

A. Chakrabarti, S. Dechoudhury, V. Naik
VECC, Kolkata, India
F. Ames, R.A. Baartman, Y.-C. Chao, R.E. Laxdal, M. Marchetto, L. Merminga, F. Yan
TRIUMF, Vancouver, Canada
G. Goh
SFU, Burnaby, BC, Canada

Funding: This project is funded by Department of Atomic Energy, India
In the first phase of ongoing collaboration between VECC (India) and TRIUMF (Canada) a 10 MeV superconducting electron linac injector will be installed at VECC. This will constitute a 100 keV DC thermionic gun with grid delivering pulsed electron beam at 650 MHz. Owing to low energy from the gun, a capture cryo-module (CCM) consisting of two β = 1 single cell elliptical cavities (frequency = 1.3 GHz) will be inserted before a 9-cell β = 1 elliptical cavity that will provide acceleration to 10 MeV. The present paper depicts the beam dynamics simulation and optimization of different parameters for the injector with a realistic simulated beam emittance from the electron gun.

MOPB029

Commissioning of the X-Band Test Area at SLAC

gun, cathode, laser, injection

234

C. Limborg-Deprey, C. Adolphsen, M.P. Dunning, S. Gilevich, C. Hast, R.K. Jobe, D.J. McCormick, A. Miahnahri, T.O. Raubenheimer, A.E. Vlieks, D.R. Walz, S.P. Weathersby
SLAC, Menlo Park, California, USA

Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515.
The X-Band Test Area (XTA) is being assembled in the NLCTA tunnel at SLAC to serve as a test facility for new X-Band RF guns. The first gun to be tested is an upgraded version of the 5.6 cell, 200 MV/m peak field X-band gun designed at SLAC in 2003 for the Compton Scattering experiment run in ASTA [1]. The XTA beamline is equipped with diagnostics to measure both the longitudinal phase space and the transverse phase space properties of the beam after it has reached 100 MeV. We will review design choices and present some early commissioning results.
[1] A.E. Vlieks, et al. “Recent measurements and plans for the SLAC Compton X-ray source”, SLAC-PUB-11689, 2006. 10pp. Published in AIP Conf. Proc.807:481-490, 2006

MOPB032

Stabilization of the Beam Intensity in the Linac at the CTF3 CLIC Test Facility

linac, gun, controls, feedback

243

A. Dubrovskiy
JINR, Dubna, Moscow Region, Russia
B.N. Bathe, S. Srivastava
BARC, Mumbai, India
F. Tecker
CERN, Geneva, Switzerland

A new electron beam stabilization system has been introduced in CTF3 in order to open new possibilities for CLIC beam studies in ultra-stable conditions and to provide a sustainable tool to keep the beam intensity and energy at its reference values for long term operations. The stabilization system is based on a pulse-to-pulse feedback control of the electron gun to compensate intensity deviations measured at the end of the injector and at the beginning of the linac. Thereby it introduces negligible beam distortions at the end of the linac and it significantly reduces energy deviations. A self-calibration mechanism has been developed to automatically configure the feedback controller for the optimum performance. The residual intensity jitter of 0.045% of the stabilized beam was measured whereas the CLIC requirement is 0.075%.

MOPB033

High Power Coupler Test for TRIUMF E-linac SC Cavities

vacuum, linac, TRIUMF, monitoring

246

A.K. Mitra, Z.T. Ang, S. Calic, P.R. Harmer, S.R. Koscielniak, R.E. Laxdal, W.R. Rawnsley, R.W. Shanks
TRIUMF, Vancouver, Canada

TRIUMF has been funded to build an electron linac with a final energy of 50 MeV and 500 kW beam power using TESLA type 9 cell superconducting cavities operating at 1.3 GHz at 2 Kelvin. The e-linac consists of an electron gun, buncher cavity, injector cryomodule, and two main-linac cryomodules. The injector module has one 9-cell cavity whereas each of the accelerating main-linac cryomodules contains two 9-cell cavities. It is scheduled to install the injector and one main accelerating cryomodule by 2014. Six power couplers, each rated for 60 kW cw, have been procured for three cavities. The injector cryomodule will be fed by a 30 kW cw inductive Output Tube (IOT) and the accelerating cryomodule will be powered by a 290 kW cw klystron. In order to install the power couplers in the cavities, they are to be assembled and conditioned with high power rf source. A power coupler test station has been built and tests of two power couplers have began. A 30 kW IOT has been commissioned to full output power and it will be used for the power coupler test. In this paper, test results of the rf conditioning of the power couplers under pulse and cw mode will be described.

MOPB034

Novel Technique of Suppressing TBBU in High-energy ERLs

linac, HOM, SRF, lattice

249

V. Litvinenko
BNL, Upton, Long Island, New York, USA

Energy recovery linacs (ERLs) is emerging generation of accelerators promising revolutionize the fields of high-energy physics and photon sciences. One potential weakness of these devices is transverse beam-breakup instability, which may severely limit available beam current. In this paper I am presenting new idea [1] developed for high-energy ERL which could be used for eRHIC, LHeC and, potentially, ILC: a concept of using main ERL linacs and natural chromaticity to suppressing TBBU instabilities by simplifying an ERL lattice. As demonstration of this method, I present tow specific example of eRHIC and LHeC ERLs.
[1] V.N. Litvinenko, Chromaticity of the lattice and beam stability in energy recovery linacs, submitted to PR ST-AB

MOPB035

The Linear Accelerating Structure Development for HLS Upgrade

cavity, linac, injection, bunching

252

K. Jin, Y. Hong, G. Huang, D. Jia, S.C. Zhang
USTC/NSRL, Hefei, Anhui, People's Republic of China

Hefei Light Source (HLS) is mainly composed of an 800 MeV electron storage ring and a 200 MeV constant-impedance Linac functioning as its injector. A new Linac is developed in view of the Full Energy Injection and the Top-up Injection scheme will be adopted in the HLS upgrade. In this paper, an 800 MeV linear accelerating system construction, the constant-gradient structure design and the symmetry couplers consideration will be described in detail. The manufacture technology, the RF measurement, the high power test results and the accelerating system operation are presented.

MOPB038

Single Shot Bunch-by-Bunch Beam Emittance Measurement of the SPring-8 Linac

linac, injection, emittance, dipole

261

Y. Shoji, K. Takeda
LASTI, Hyogo, Japan

Bunch by bunch emittance of a single shot beam from the SPring-8 electron linac was measured. The linac is operated as an injector to the electron storage ring, NewSUBARU. A high beam stability is required for the stable top-up injection into the ring with a small acceptance. We used the electron ring as a part of the measurement system. The electron beam from the linac was injected into the ring and circulated for many turns. The beam profiles were recorded by a dual-sweep streak camera using the visible light in the ring. The fast sweep separated the bunches in 1 ns macro pulse and the slow sweep separated the profiles at different revolutions. It enabled a multi-record of beam profiles in one camera frame. Betatron oscillation in the ring produced the phase space rotation for the reconstruction of the beam emittance. The ring parameters were optimized for the measurement because the beam storage was not necessary. A stability of the linac beam was evaluated from the shot by shot fluctuation of the emittance and the bunch structure. We also compared the emittances of a front bunch and a rear bunch in the same pulse.

MOPB041

Advances in Beam Tests of Dielectric Based Accelerating Structures

wakefield, acceleration, laser, linac

264

A. Kanareykin, S.P. Antipov, J.E. Butler, C.-J. Jing
Euclid TechLabs, LLC, Solon, Ohio, USA
W. Gai
ANL, Argonne, USA
V. Yakimenko
BNL, Upton, Long Island, New York, USA

Funding: US Department of Energy
Diamond is being evaluated as a dielectric material for dielectric loaded accelerating structures. It has a very low microwave loss tangent, high thermal conductivity, and supports high RF breakdown fields. We report on progress in our recent beam tests of the diamond based accelerating structures of the Ka-band and THz frequency ranges. Wakefield breakdown test of a diamond-loaded accelerating structure has been carried out at the ANL/AWA accelerator. The high charge beam from the AWA linac (~70 nC, σ_z = 2.5 mm) was passed through a rectangular diamond loaded resonator and induce an intense wakefield. A groove is cut on the diamond to enhance the field. Electric fields up to 0.3 GV/m has been detected on the diamond surface to attempt to initiate breakdown. A surface analysis of the diamond has been performed before and after the beam test. Wakefield effects in a 250 GHz planar diamond accelerating structure has been observed at BNL/ATF accelerator as well. We have directly measured the mm-wave wake fields induced by subpicosecond, intense relativistic electron bunches in a diamond loaded accelerating structure via the dielectric wake-field acceleration mechanism.

MOPB046

A 10 MeV L-band Linac for Irradiation Applications in China

linac, gun, klystron, simulation

276

G. Pei, Y.L. Chi, M.H. Dai, D.Y. He, X. He, X. Li, J. Liu, C. Ma, X. Wang, X.W. Yang, C.H. Yu, F. Zhao, J. Zhao, Z.S. Zhou
IHEP, Beijing, People's Republic of China
Y. Feng, H. Huang, S. Shi, E. Tang, X. Yang, Q. Yuan, Z. Zhu
Institute of High Energy Physics (IHEP), People's Republic of China
Z. Li, X. Zhang
Wuxi EL PONT Radiation Technology Ltd, Wuxi, People's Republic of China

The electron linear accelerator has wide applications, and the demands are keeping growing for the irradiation applications in China. A high beam power 10 MeV L-band Linac has been developed recently as a joint venture of Institute of High Energy Physics and EL-PONT Company. The Thales TH2104U klystron, 3 A thermionic electron gun and three meter L-band disk-loaded constant impedance RF structure are adopted. A stable electron beam of 10 MeV, 40 kW has been obtained in the last May with a microwave to beam efficiency of about 65%. In this paper we will present the detailed design issues and beam commissioning.

MOPB047

Applications of Compact Dielectric Based Accelerators

coupling, multipactoring, wakefield, impedance

279

C.-J. Jing, S.P. Antipov, A. Kanareykin, P. Schoessow
Euclid TechLabs, LLC, Solon, Ohio, USA
M.E. Conde, W. Gai, J.G. Power
ANL, Argonne, USA

Important progress on the development of dielectric based accelerators has been made experimentally and theoretically in the past few years. One advantage of dielectric accelerators over the metallic counterparts is its compact size, which may attract some applications in industrial or medical accelerators. In this article, we discuss the design and technologies of dielectric based accelerators toward these needs.

MOPB048

Linear Accelerator Based on Parallel Coupled Accelerating Structure

cavity, controls, focusing, klystron

282

A.E. Levichev, A.M. Barnyakov, V.M. Pavlov
BINP SB RAS, Novosibirsk, Russia
Y.D. Chernousov
ICKC, Novosibirsk, Russia
V. Ivannikov, I.V. Shebolaev
ICKC SB RAS, Novosibirsk, Russia

Accelerating stand based on parallel coupled accelerating structure and electron gun is developed and produced. The structure consists of five accelerating cavities. The RF power feeding of accelerating cavities is provided by common exciting cavity which is performed from rectangular waveguide loaded by reactive pins. Operating frequency is 2450 MHz. Electron gun is made on the basis of RF triode. Linear accelerator was tested with different working regimes. The obtained results are following: energy is up to 4 MeV, accelerating current is up to 300 mA with pulse duration of 2.5 ns on the half of the width; energy is up to 2.5 MeV, accelerating current is up to 100 mA with pulse duration of 5 μs; energy is up to 2.5 MeV, accelerating current is up to 120 mA with pulse duration of 5 μs and beam capture of 100%. The descriptions of the accelerator elements are given in the report. The features of the parallel coupled accelerating structure are discussed. The results of the measuring accelerator’s parameters are presented.

MOPB049

Design of Compact C-Band Standing-Wave Accelerator for Medical Radiotherapy

coupling, bunching, focusing, cavity

285

H. Yang, M.-H. Cho, W. Namkung
POSTECH, Pohang, Kyungbuk, Republic of Korea
S.H. Kim
ANL, Argonne, USA
J.-S. Oh
NFRI, Daejon, Republic of Korea

Funding: Work supported by POSTECH Physics BK21 Program.
We design a C-band standing-wave accelerator for an X-ray and electron source of medical radiotherapy. The accelerator system is operated two modes, using the X-ray and electron beams. Since two modes require different energy, the accelerator is capable of producing 6-MeV, 100-mA pulsed electron beams with peak 2-MW RF power, and 7.5-MeV, 50 mA electron beams with peak 2.5-MW RF power. The beam is focused by less than 1 mm without external magnets. The accelerating structure is a bi-periodic and on-axis-coupled structure with a built-in bunching section, which consists of 3 bunching cells, 14 normal cells and a coupling cell. It is operated with the π/2-mode standing-wave. The bunching cells are designed to enhance the RF phase focusing. Each cavity is designed by the MWS code within 3% inter-cell coupling. In this paper, we present design details of RF cavities and the beam dynamics.

MOPB051

Changing Attitude to Radiation Hazards and Consequent Opportunities for LINAC Applications

radiation, linac, background, status

288

Y. Socol
Falcon Analytics, Netanya, Israel

High-energy LINACs unavoidably yield ionizing radiation. This fact makes them subject to strict regulations and considerably limits applications. During the last two decades the attitude to ionizing radiation hazards seems to become more balanced, as opposed to "radiophobia" of the Cold-War era. Scientifically, the linear no-threshold (LNT) model of radiation damage is more and more questioned. Moreover, the hypotheses of radiation hormesis - beneficial effect of low-dose radiation - is studied. While this scientific debate has not yet given fruit regarding radiation regulation and policy, we may expect this in near to middle term. Namely, the ALARA (as low as reasonably achievable) demand is anticipated to be substituted by some tolerance level, which in turn is anticipated to be very high according to the present standards. The presentation will review the present status of the radiation-hazard debate, and outline anticipated opportunities for LINAC applications, like compact designs and wider industrial outreach.

MOPB056

Multipacting Analysis of High-Velocity Superconducting Spoke Resonators

cavity, site, simulation, superconductivity

303

C.S. Hopper, J.R. Delayen
ODU, Norfolk, Virginia, USA

Some of the advantages of superconducting spoke cavities are currently being investigated for the high-velocity regime. When determining a final, optimized geometry, one must consider the possible limiting effects multipacting could have on the cavity. We report on the results of analytical calculations and numerical simulations of multipacting electrons in superconducting spoke cavities and methods for reducing their impact.

MOPB061

The New 2nd Generation SRF R&D Facility at Jefferson Lab: TEDF

SRF, cryomodule, cavity, cryogenics

315

C.E. Reece, A.V. Reilly
JLAB, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
The US Department of Energy has funded a near-complete renovation of the SRF-based accelerator research and development facilities at Jefferson Lab. The project to accomplish this, the Technical and Engineering Development Facility (TEDF) Project has completed the first of two phases. An entirely new 3,300 m² purpose-built SRF technical work facility has been constructed and is being occupied in summer of 2012. All SRF work processes with the exception of cryogenic testing has been relocated into the new building. All cavity fabrication, processing, thermal treatment, chemistry, cleaning, and assembly work is collected conveniently into a new LEED-certified building. An innovatively designed 750 m² cleanroom/chemrooms suite provides long-term flexibility for support of multiple R&D and construction projects as well as continued process evolution. The detailed characteristics of this perhaps first 2nd-generation SRF facility will be described.

MOPB063

Superconducting RF Linac for eRHIC

cavity, linac, SRF, HOM

321

S.A. Belomestnykh, I. Ben-Zvi, J.C. Brutus, H. Hahn, D. Kayran, V. Litvinenko, G.J. Mahler, G.T. McIntyre, V. Ptitsyn, R. Than, J.E. Tuozzolo, W. Xu, A. Zaltsman
BNL, Upton, Long Island, New York, USA
S.A. Belomestnykh
Stony Brook University, Stony Brook, USA

Funding: Work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE.
eRHIC will collide high-intensity hadron beams from RHIC with 50-mA electron beam from a six-pass 30-GeV Energy Recovery Linac (ERL), which will utilize 704 MHz superconducting RF accelerating structures. This presentation describes the eRHIC SRF linac requirements, layout and parameters, 5-cell SRF cavity with a new HOM damping scheme, project status and plans.

MOPB064

Developing of Superconducting RF Guns at BNL

gun, SRF, cathode, cavity

324

S.A. Belomestnykh, Z. Altinbas, I. Ben-Zvi, J.C. Brutus, D.M. Gassner, H. Hahn, L.R. Hammons, J.P. Jamilkowski, D. Kayran, J. Kewisch, V. Litvinenko, G.J. Mahler, G.T. McIntyre, D. Pate, D. Phillips, T. Rao, S.K. Seberg, T. Seda, B. Sheehy, J. Skaritka, K.S. Smith, R. Than, J.E. Tuozzolo, E. Wang, Q. Wu, W. Xu, A. Zaltsman
BNL, Upton, Long Island, New York, USA
S.A. Belomestnykh, J. Dai, M. Ruiz-Osés, T. Xin
Stony Brook University, Stony Brook, USA
C.H. Boulware, T.L. Grimm
Niowave, Inc., Lansing, Michigan, USA
A. Burrill
JLAB, Newport News, Virginia, USA
R. Calaga
CERN, Geneva, Switzerland
M.D. Cole, A.J. Favale, D. Holmes, J. Rathke, T. Schultheiss, A.M.M. Todd
AES, Medford, NY, USA
X. Liang
SBU, Stony Brook, New York, USA

Funding: Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE. The work at Niowave is supported by the US DOE under SBIR contract No. DE-FG02-07ER84861.
BNL is developing several superconducting RF guns for different applications. The first gun is based on a half-cell 1.3 GHz elliptical cavity. This gun is used to study generation of polarized electrons from GaAs photocathodes. The second gun, also of a half-cell elliptical cavity design, operates at 704 MHz and is designed to produce high average current electron beam for the ERL prototype from a multi-alkali photocathodes. The third gun is of a quarter-wave resonator type, operating at 112 MHz. This gun will be used for photocathode studies, including a diamond-amplified cathode, and to generate high charge, low repetition rate beam for the coherent electron cooling experiment. In this presentation we will briefly describe the gun designs, present recent test results and discuss future plans.

MOPB069

Study of HPR Created Oxide Layer at Nb Surfaces

SRF, vacuum, cavity, ion

336

P.V. Tyagi
Sokendai, Ibaraki, Japan
H. Hayano, S. Kato, T. Saeki, M. Sawabe
KEK, Ibaraki, Japan

The performance of superconducting radio frequency (SRF) niobium (Nb) cavities strongly depends on final surface condition. Therefore the surface preparation of these SRF cavities often becomes critical. The preparation of surface includes two steps; surface chemistry (in order to get a smooth surface) and cleaning/rinsing (in order to remove contaminants left after the surface chemistry). As high pressure rinsing (HPR) with ultra pure water (UPW) is most commonly used surface cleaning method after the surface chemistry, it's very interesting to characterize the Nb surfaces after HPR. Results of our surface characterization done by XPS (x-ray photoelectron spectroscopy) with depth profiling show the presence of a thicker oxide surface characterization results show the presence of a thicker oxide layer at Nb surface as an outcome of HPR. In this article, we report the production of oxide layer (FWHM thickness) based on different conditions such as the pressures and doses.

MOPB079

Normal Conducting Deflecting Cavity Development at the Cockcroft Institute

cavity, beam-loading, wakefield, damping

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

klystron, coupling, controls, FEL

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

acceleration, linac, impedance, proton

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.

MOPB084

Design of a C-band Disk-loaded Type Accelerating Structure for a Higher Pulse Repetition Rate in the SACLA Accelerator.

cavity, laser, wakefield, accelerating-gradient

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.

MOPB089

X-Ray Local Energy Spectrum Measurement at Tsinghua Thomson Scattering X-Ray Source (TTX)

scattering, simulation, laser, photon

383

Y.-C. Du, J.F. Hua, W.-H. Huang, C.-X. Tang, L.X. Yan, H. Zha, Z. Zhang
TUB, Beijing, People's Republic of China

Thomson scattering X-ray source, in which the TW laser pulse is scattered by the relativistic electron beam, can provide ultra short, monochromatic, high flux, tunable polarized hard X-ray pulse which is can widely used in physical, chemical and biological process research, ultra-fast phase contrast imaging, and so on. Since the pulse duration of X-ray is as short as picosecond and the flux in one pulse is high, it is difficult to measure the x-ray spectrum. In this paper, we present the X-ray spectrum measurement experiment on Tsinghua Thomson scattering. The preliminary experimental results shows the maximum X-ray energy is about 47 keV, which is agree well with the simulations.

MOPB093

The Upgraded Argonne Wakefield Accelerator Facility (AWA): a Test-Bed for the Development of High Gradient Accelerating Structures and Wakefield Measurements

wakefield, gun, linac, acceleration

392

M.E. Conde, D.S. Doran, W. Gai, R. Konecny, W. Liu, J.G. Power, Z.M. Yusof
ANL, Argonne, USA
S.P. Antipov, C.-J. Jing
Euclid TechLabs, LLC, Solon, Ohio, USA
E.E. Wisniewski
Illinois Institute of Technology, Chicago, Illinois, USA

Funding: Work supported by the U.S. Department of Energy under contract No. DE-AC02-06CH11357.
Electron beam driven wakefield acceleration is a bona fide path to reach high gradient acceleration of electrons and positrons. With the goal of demonstrating the feasibility of this concept with realistic parameters, well beyond a proof-of-principle scenario, the AWA Facility is currently undergoing a major upgrade that will enable it to achieve accelerating gradients of hundreds of MV/m and energy gains on the order of 100 MeV per structure. A key aspect of the studies and experiments carried out at the AWA facility is the use of relatively short RF pulses (15 – 25 ns), which is believed to mitigate the risk of breakdown and structure damage. The upgraded facility will utilize long trains of high charge electron bunches to drive wakefields in the microwave range of frequencies (8 to 26 GHz), generating RF pulses with GW power levels.

TU2A02

Overview of SACLA Machine Status

undulator, laser, gun, emittance

427

Y. Otake
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan

SACLA of an X-ray free-electron laser has been constructed and was successfully lased at 0.06 nm in 2011. SACLA mainly comprises a low-emittance thermionic electron gun, an 8-GeV linear accelerator using C-band (5712 MHz) cavities and 18 in-vacuum undulators. The concept to develop this machine is compactness compared with the other machine, such as LCLS with the length of more than 1 km. Stable X-ray lasing up to 0.06 nm as also the concept demands extreme stable accelerator components, such as 50 fs temporal stability at a cavity in an injector. We now realized a 700 m compact machine by a low-emittance at the electron gun, an accelerating gradient of more than 35 MV/m with the C-band accelerator, and the short-period undulators. The continuous lasing for more than several days is strongly supported by these stable components and small operator‘s trimming, and also established by reduction of perturbation sources to laser instability. SACLA is regularly operated for user experiments, such as the imaging with extreme amount of data. This presentation introduces the machine performance, the reduction of the perturbation sources and the operation of SACLA.

Slides TU2A02 [28.971 MB]

TU2A03

LCLS Operation Experience and LCLS-II Design

undulator, linac, photon, FEL

432

T.O. Raubenheimer
SLAC, Menlo Park, California, USA

This talk will report the operations experience at LCLS and will describe the LCLS-II, a new X-ray FEL facility that uses the middle 1/3 of the SLAC linac as compared to the LCLS which uses the last 1/3 of the SLAC linac.

Slides TU2A03 [4.761 MB]

TU2A04

High Current ERL at BNL

linac, gun, SRF, cavity

437

I. Ben-Zvi
BNL, Upton, Long Island, New York, USA

The electron hadron collider eRHIC will collide polarized and unpolarized electrons with a current of 50 mA and energy in the range of 5 GeV to 30 GeV with hadron beams, including heavy ions or polarized light ions of the RHIC storage ring. The electron beam will be generated in an energy recovery linac contained inside the RHIC tunnel, comprising six passes through two linac section of about 2.5 GeV each. The electron ERL poses many challenges in term of a high-current high-polarization electron gun, HOM damping in the linac, crab cavities, harmonic cavities and beam stability.

Slides TU2A04 [2.227 MB]

TUPLB01

The Swiss FEL RF Gun: RF Design and Thermal Analysis

gun, coupling, cathode, linac

442

J.-Y. Raguin, M. Bopp, A. Citterio, A. Scherer
PSI, Villigen, Switzerland

We report here on the design of a dual-feed S-band 2.5 cell RF gun, developed in the framework of SwissFEL, capable of operating at 100 Hz repetition rate. As in the LCLS RF gun, z-coupling, to reduce the pulsed surface heating, and a racetrack coupling cell shape, to minimize the quadrupolar component of the fields, have been adopted. The cell lengths and the iris thicknesses are as in the PHIN gun operating at CERN. However the irises aperture has been enlarged to obtain a frequency separation between the operating π mode and the π/2 mode higher than 15 MHz. An amplitude modulation scheme of the RF power, which allows one to obtain a flat plateau of 150 ns for multibunch operation and a reduced average power is presented as well. With an RF pulse duration of 1μs it is shown that operation at 100 MV/m and 100 Hz repetition rate is feasible with very reasonable thermal stresses.

Slides TUPLB01 [1.679 MB]

TUPLB05

Computational Model Analysis for Experimental Observation of Optical Current Noise Suppression below the Shot-Noise Limit

plasma, linac, simulation, beam-transport

451

A. Gover
University of Tel-Aviv, Faculty of Engineering, Tel-Aviv, Israel
A. Nause
University of Tel Aviv, Tel Aviv, Israel

Funding: We acknowledge support of the Israel Science Foundation grant
We report first demonstration of optical frequency current shot-noise suppression in a relativistic e-beam. This process is made possible by collective Coulomb interaction between the electrons of a cold intense beam during beam drift, and is essentially a process of longitudinal beam-plasma oscillation [1]. Suppression of beam current noise below the classical “shot-noise” level has been known in the microwave tubes art [2]. This is the first time that it is demonstrated in the optical regime. We predict that the scheme can be extended to the XUV and possibly to shorter wavelengths with further development of technology. The fundamental current shot-noise determines the level of incoherent spontaneous radiation emission from electron-beam optical radiation sources and SASE-FELs [3]. Suppressing shot-noise would make it possible to attain spontaneous emission sub-radiance [4] and surpass the classical coherence limits of seed-injected FELs. The effect was demonstrated by measuring sub-linear growth as a function of current of the OTR Radiation. This finding indicates that the beam charge homogenizes due to the collective interaction, and its distribution becomes sub-Poissonian.
[1] A. Gover, E. Dyunin, PRL, 102, 154801, 2009
[2] H. Haus, N. Robinson, Proc. IRE, 43, 981 (1955)
[3] P. Emma, et al , Nature Photonics 4, 641 (2010)
[4] A. Dicke, Phys. Rev. 93, 99 (1954)

TUPLB07

Reduced-beta Cavities for High-intensity Compact Accelerators

cavity, ion, niobium, heavy-ion

458

Z.A. Conway, S.M. Gerbick, M. Kedzie, M.P. Kelly, J.W. Morgan, R.C. Murphy, P.N. Ostroumov, T. Reid
ANL, Argonne, USA

Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under contract number DE-AC02-06CH11357 and WFO 8R268.
This paper reports on the development and testing of a superconducting quarter-wave and a superconducting half-wave resonator. The quarter-wave resonator is designed for β = 0.077 ions, operates at 72 MHz and can provide more than 7.4 MV of accelerating voltage at the design beta, with peak surface fields of 164 mT and 117 MV/m. Operation was limited to this level not by RF surface defects but by our available RF power and administrative limits on x-ray production. A similar goal is being pursued in the development of a half-wave resonator designed for β = 0.29 ions and operated at 325 MHz.

TUPLB09

Design and Beam Test of Six-electrode BPMs for Second-order Moment Measurement

factory, multipole, linac, storage-ring

464

K. Yanagida, H. Hanaki, S. Suzuki
JASRI/SPring-8, Hyogo-ken, Japan

In the SPring-8 linac, four-electrode beam position monitors (BPMs) have been utilized for the measurement of the transverse first-order moments, which correspond to the centroids of beam charge distributions. We have planed to measure the transverse second-order moments of beams to obtain information of beam optics and its energy deviations during the top-up beam injection without destruction of beams. Therefore, six-electrode BPMs with circular and quasi-ellipse cross-sections have been developed on the basis of a newly introduced theory. A low-noise signal processor for the six-electrode BPM has also been developed to perform fine measurement. We expected the following resolutions determined by the S/N ratio of the circuit; the first order moments (beam positions) > 1 μm, and the second order moments with a size > 110 μm. The first beam test was carried out using the six-electrode BPM with circular cross-section and the old signal processor. The measured sensitivities and resolutions of the second-order moments showed good agreement with the theory.

Slides TUPLB09 [8.248 MB]

TUPLB10

Non-destructive Real-time Monitor to Measure 3D-bunch Charge Distribution with Arrival Timing to Maximize 3D Overlapping for HHG-seeded EUV-FEL

FEL, laser, feedback, optics

467

H. Tomizawa, K. Ogawa, T. Sato, M. Yabashi
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
M. Aoyama
JAEA/Kansai, Kyoto, Japan
A. Iwasaki, S. Owada
The University of Tokyo, Tokyo, Japan
S. Matsubara, Y. Okayasu, T. Togashi
JASRI/SPring-8, Hyogo, Japan
T. Matsukawa, H. Minamide
RIKEN ASI, Sendai, Miyagi, Japan
E. Takahashi
RIKEN, Saitama, Japan

Non-destructive, shot-by-shot real-time monitors have been developed to measure 3D bunch charge distribution (BCD). This 3D monitor has been developed to monitor 3-D overlapping electron bunches and higher harmonic generation (HHG) pulses in a seeded VUV-FEL. This ambitious monitor is based on an Electro-Optic (EO) multiple sampling technique in a manner of spectral decoding that is non-destructive and enables real-time measurements of the longitudinal and transverse BCD. This monitor was materialized in simultaneously probing eight EO crystals that surround the electron beam axis with a radial polarized and hollow EO-probe laser pulse. In 2009, the concept of 3D-BCD monitor was verified through electron bunch measurements at SPring-8. The further target of the temporal resolution is ~30 fs (FWHM), utilizing an organic EO crystal (DAST) instead of conventional inorganic EO crystals (ZnTe, GaP, etc.) The EO-sampling with DAST crystal is expected to measure a bunch length less than 30 fs (FWHM). In 2011, the first bunch measurement with an organic EO crystal (DAST) was successfully demonstrated in the VUV-FEL accelerator at SPring-8.

Slides TUPLB10 [2.713 MB]

TUPB005

Computational Model Analysis for Experimental Observation of Optical Current Noise Suppression Below the Shot-noise Limit

plasma, linac, simulation, beam-transport

482

A. Gover
University of Tel-Aviv, Faculty of Engineering, Tel-Aviv, Israel
A. Nause
University of Tel Aviv, Tel Aviv, Israel

Funding: We acknowledge support of the Israel Science Foundation grant
We report first demonstration of optical frequency current shot-noise suppression in a relativistic e-beam. This process is made possible by collective Coulomb interaction between the electrons of a cold intense beam during beam drift, and is essentially a process of longitudinal beam-plasma oscillation.[1] Suppression of beam current noise below the classical “shot-noise” level has been known in the microwave tubes art [2]. This is the first time that it is demonstrated in the optical regime. We predict that the scheme can be extended to the XUV and possibly to shorter wavelengths with further development of technology. The fundamental current shot-noise determines the level of incoherent spontaneous radiation emission from electron-beam optical radiation sources and SASE-FELs [3]. Suppressing shot-noise would make it possible to attain spontaneous emission sub-radiance [4] and surpass the classical coherence limits of seed-injected FELs. The effect was demonstrated by measuring sub-linear growth as a function of current of the OTR Radiation. This finding indicates that the beam charge homogenizes due to the collective interaction, and its distribution becomes sub-Poissonian.
[1] A. Gover, E. Dyunin, PRL, 102, 154801, 2009
[2] H. Haus, N. Robinson, Proc. IRE, 43, 981 (1955)
[3] P. Emma, et al , Nature Photonics 4, 641 (2010)
[4] A. Dicke, Phys. Rev. 93, 99 (1954)

TUPB008

Major Trends in Linac Design for X-ray FELs

FEL, linac, cathode, emittance

489

A. Zholents
ANL, Argonne, USA

Funding: This work was supported by the U.S. Department of Energy under Contract No. DE-AC02-06CH11357.
Major trends in the contemporary linac designs for x-ray free-electron lasers (XFELs) are outlined starting with identification of the key performance parameters, continuing with considerations of the design options for the electron gun and linac, and finishing with electron beam manipulation in the phase space.

TUPB010

The Swiss FEL RF Gun: RF Design and Thermal Analysis

gun, coupling, cathode, linac

495

J.-Y. Raguin, M. Bopp, A. Citterio, A. Scherer
PSI, Villigen, Switzerland

We report here on the design of a dual-feed S-band 2.5 cell RF gun, developed in the framework of SwissFEL, capable of operating at 100 Hz repetition rate. As in the LCLS RF gun, z-coupling, to reduce the pulsed surface heating, and a racetrack coupling cell shape, to minimize the quadrupolar component of the fields, have been adopted. The cell lengths and the iris thicknesses are as in the PHIN gun operating at CERN. However the irises aperture has been enlarged to obtain a frequency separation between the operating π mode and the π/2 mode higher than 15 MHz. An amplitude modulation scheme of the RF power, which allows one to obtain a flat plateau of 150 ns for multibunch operation and a reduced average power is presented as well. With an RF pulse duration of 1μs it is shown that operation at 100 MV/m and 100 Hz repetition rate is feasible with very reasonable thermal stresses.

TUPB013

Update on the Commissioning Effort at the SwissFEL Injector Test Facility

emittance, laser, quadrupole, optics

504

T. Schietinger
PSI, Villigen, Switzerland

The SwissFEL Injector Test Facility at the Paul Scherrer Institute is the principal test bed and demonstration plant for the SwissFEL project, which aims at realizing a hard-X-ray Free Electron Laser by 2017. Since the spring of 2012 the photoinjector facility has been running with all RF cavities in full operation, allowing beam characterization at energies around 230 MeV with bunch charges between 10 and 200 pC. We give an overview of recent commissioning efforts with particular emphasis on efforts to optimize the emittance of the uncompressed beam.

TUPB014

Comparative Design of Single Pass, Photo-cathode RF-LINAC FEL for the THz Frequency Range: Self Amplification vs. Enhanced Super-radiance

FEL, radiation, linac, wiggler

507

Yu. Lurie, Y. Pinhasi
Ariel University Center of Samaria, Faculty of Engineering, Ariel, Israel

Self amplified spontaneous emission and enhanced super-radiance are discussed and compared as possible configurations in the construction of a single-pass, photo-cathode RF-LINAC FEL source for THz radiation, being developed in Ariel University Center of Samaria. Numerical simulations carried out using 3D, space-frequency approach demonstrate the charge squared dependence of the radiation power in both cases, the characteristic typical to super-radiant emission. The comparison reveals a high efficiency of an enhanced super-radiance FEL, which however can only be achieved with ultra-short (the radiation wavelength long or shorter) drive electron beam bunches at a proper energy chirping.

TUPB021

Study of Plasma Effect in Longitudinal Space Charge Induced Microbunching Instability

plasma, impedance, linac, space-charge

522

D. Huang, Q. Gu
SINAP, Shanghai, People's Republic of China
K.Y. Ng
Fermilab, Batavia, USA

The longitudinal space charge (LSC) plays an important role in introducing the microbunching instability in the LINAC of a free electron laser (FEL) facility. The current model of LSC impedance [1] derived from the fundamental electromagnetic theory [2] is widely used to explain the growth of the microbunching instability [3]. However, in the case of highly bright relativistic electron beams, the plasma effect starts to play a role. In this article, the basic model of LSC impedance including the plasma effect is built , and the modifications to the microbunching instability based on the new model are discussed in various conditions.
[1] Marco Venturini, Phys Rev. ST Accel. Beams 11, 034401 (2008)
[2] J. D. Jackson, Classical Electrodynamics (Wiley, 1999)
[3] Z. Huang, et. al., Phys, Rev. ST Accel. Beams 7, 074401 (2004)

TUPB022

A Passive Linearizer for Bunch Compression

FEL, linac, laser, emittance

525

Q. Gu, M. Zhang, M.H. Zhao
SINAP, Shanghai, People's Republic of China

In high gain free electron laser (FEL) facility design and operation, a high bunch current is required to get lasing with a reasonable gain length. Because of the current limitation of the electron source due to the space charge effect, a compression system is commonly used to compress the electron beam to the exact current needed. Before the bunch compression, the nonlinear energy spread due to the finite bunch length should be compensated; otherwise the longitudinal profile of bunch will be badly distorted. Usually an X band accelerating structure is used to compensate the nonlinear energy spread while decelerating the beam. For UV FEL facility, the X band system is too expensive comparing to the whole facility. In this paper, we present a corrugated structure as a passive linearizer, and the preliminary study of the beam dynamics is also shown.

TUPB023

The Optimization of RF Deflector Input Power Coupler

coupling, emittance, simulation, diagnostics

528

A.Yu. Smirnov, O.A. Adonev, P.V. Binyukov, N.P. Sobenin
MEPhI, Moscow, Russia

This paper concerns the investigation of different types of input power cell for S-band RF electron deflector. This device serving for slice emittance diagnostics is a disc-loaded waveguide which operates with TE11-like wave in traveling wave regime with 120 deg phase shift per cell. Since this deflector meets the restriction on its length and has to provide high enough deflecting potential to a particle during its flight time it is significant to increase the transversal field strength in coupling cell or to shorten it so that the deflecting potential remains constant. The total structure consists of 14 regular cells and two couplers. As it is now all cells have the same length equal to D=33.34 mm and the field in couplers is lower than that of regular cells. In this paper different length are considered and numerically simulated in order to choose the best one.

TUPB026

Measurements of a Reduced Energy Spread of a Recirculating Linac by Non-isochronous Beam Dynamics

recirculation, linac, synchrotron, acceleration

531

F. Hug, C. Burandt, M. Konrad, N. Pietralla
TU Darmstadt, Darmstadt, Germany
R. Eichhorn
Cornell University, Ithaca, New York, USA

Funding: supported by DFG through SFB 634
The Superconducting Linear Accelerator S-DALINAC at the University of Darmstadt (Germany) is a recirculating linac with two recirculations providing beams for measurements in nuclear physics at small momentum transfers. For these experiments an energy spread of better than 10^-4 (rms) is needed. Currently acceleration in the linac section is done on crest of the accelerating field. The recirculation path is operated achromatic and isochronous. In this recirculation scheme the energy spread of the resulting beam in the ideal case is determined by the electron bunch length. Taking into account the stability of the RF system the energy spread increases drastically to more than 10^-3 (rms). We will present a new non-isochronous recirculation scheme which helps cancelling out these errors from the rf-control. This scheme uses longitudinal dispersion in the recirculation paths and an acceleration off-crest with a certain phase with respect to the maximum. We will present results of the commissioning of the new system including measurements of the longitudinal dispersion in the recirculation arcs as well as measurements of the resulting energy spread using an electron spectrometer.

TUPB041

Scattering of H⁻ Stripped Electrons from SEM Grids and Wire Scanners at the CERN LINAC4

simulation, scattering, linac, polarization

567

F. Roncarolo, E. Chevallay, M. Duraffourg, G.J. Focker, C. Heßler, U. Raich, VC. Vuitton, F. Zocca
CERN, Geneva, Switzerland
B. Cheymol
ESS, Lund, Sweden

At the CERN LINAC4, wire grids and scanners will be used to characterize the H⁻ beam transverse profile at different stages along the acceleration to 160 MeV. The wire signal will be determined by the balance between secondary emission and number of charges stopped in the wire, which will depend on the wire material and diameter, the possible choice of biasing (DC) the wires and the beam energy. The outermost electrons of H⁻ ions impinging on a wire are stripped in the first nanometers of material. A portion of such electrons are scattered away from the wire and can reach the neighboring wires. In addition, scattered electrons hitting the surrounding beam pipe generate secondary electrons that can also perturb the measurement. Monte Carlo simulations, analytical calculations and a laboratory experiment allowed quantifying the amount of scattering and the scattered particles distributions. The experiment was based on 70 keV electrons, well reproducing the case of 128 MeV H⁻ ions. For all the LINAC4 simulated cases the predicted effect on the beam size reconstruction results in a relative error of less than 5%.

TUPB056

The Multipacting Simulation for the New-shaped QWR using TRACK3P

cavity, simulation, accelerating-gradient, niobium

603

C. Zhang, S. He, Y. He, S.C. Huang, Y.L. Huang, T.C. Jiang, R.X. Wang, M.X. Xu, Y.Z. Yang, W.M. Yue, S.H. Zhang, S.X. Zhang, H.W. Zhao
IMP, Lanzhou, People's Republic of China

In order to improve the electro-magnetic performance of the quarter wave resonator, a new-shaped cavity with an elliptical cylinder outer conductor has been proposed. This novel cavity design can provide much lower peak surface magnetic field and much higher Ra/Q0 and G. The Multipacting simulation has been done for this new QWR cavity using ACE3P/TRACK3P code, in this paper the simulation results will be presented and analyzed.

TUPB060

Multipacting Suppression Modeling for Half Wave Resonator and RF Coupler*

simulation, cavity, cryomodule, impedance

612

Z. Zheng, A. Facco, Z. Liu, J. Popielarski, K. Saito, J. Wei, Y. Xu, Y. Zhang
FRIB, East Lansing, Michigan, USA
Z. Zheng
TUB, Beijing, People's Republic of China

Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661
In prototype cryomodule test of Facility of Rare Isotope Beam (FRIB) β=0.53 half-wave-resonators (HWRs) severe multipacting barriers, prevented RF measurement at the full field specified. The multipacting could not be removed by several hours of RF conditioning. To better understand and to eliminate multipacting, physics models and CST simulations have been developed for both cavity and RF coupler. The simulations have good agreement with the multipacting discovered in coupler and cavity testing. Proposed cavity and coupler geometric optimizations are discussed in this paper.

TUPB066

Reduced-beta Cavities for High-intensity Compact Accelerators

cavity, ion, niobium, heavy-ion

621

Z.A. Conway, S.M. Gerbick, M. Kedzie, M.P. Kelly, J.W. Morgan, R.C. Murphy, P.N. Ostroumov, T. Reid
ANL, Argonne, USA

Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under contract number DE-AC02-06CH11357 and WFO 8R268.
This paper reports on the development and testing of a superconducting quarter-wave and a superconducting half-wave resonator. The quarter-wave resonator is designed for β = 0.077 ions, operates at 72 MHz and can provide more than 7.4 MV of accelerating voltage at the design beta, with peak surface fields of 164 mT and 117 MV/m. Operation was limited to this level not by RF surface defects but by our available RF power and administrative limits on x-ray production. A similar goal is being pursued in the development of a half-wave resonator designed for β = 0.29 ions and operated at 325 MHz.

TUPB073

Design and Simulation of a Test Model for a Tri-Spoke Cavity at RIKEN

cavity, simulation, vacuum, superconducting-cavity

642

L. Lu
RIKEN, Saitama, Japan
O. Kamigaito, N. Sakamoto, K. Suda, K. Yamada
RIKEN Nishina Center, Wako, Japan

A design for a tri-spoke-type superconducting cavity for uranium beams with β = 0.303 and a 219 MHz operational frequency is presented. And a test model designed and assembled by two end-wall flanges and one triparted part of the designed tri-spoke cavity, was expected to be built using the same fabrication technology that is supposed for Nb cavity manufacture. The designs and simulations of the tri-spoke cavity and the test model will be reported in this paper.

TUPB079

Design and Beam Test of Six-Electrode BPMs for Second-Order Moment Measurement

factory, multipole, linac, storage-ring

654

K. Yanagida, H. Hanaki, S. Suzuki
JASRI/SPring-8, Hyogo-ken, Japan

In the SPring-8 linac, four-electrode beam position monitors (BPMs) have been utilized for the measurement of the transverse first-order moments, which correspond to the centroids of beam charge distributions. We have planed to measure the transverse second-order moments of beams to obtain information of beam optics and its energy deviations during the top-up beam injection without destruction of beams. Therefore, six-electrode BPMs with circular and quasi-ellipse cross-sections have been developed on the basis of a newly introduced theory. A low-noise signal processor for the six-electrode BPM has also been developed to perform fine measurement. We expected the following resolutions determined by the S/N ratio of the circuit; the first order moments (beam positions) >1 μm, and the second order moments with a size >110 μm. The first beam test was carried out using the six-electrode BPM with circular cross-section and the old signal processor. The measured sensitivities and resolutions of the second-order moments showed good agreement with the theory.

TUPB080

Non-destructive Real-time Monitor to Measure 3D Bunch Charge Distribution with Arrival Timing to Maximize 3D Overlapping for HHG-Seeded EUV-FEL

FEL, laser, feedback, optics

657

H. Tomizawa, K. Ogawa, T. Sato, M. Yabashi
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
M. Aoyama
JAEA/Kansai, Kyoto, Japan
A. Iwasaki, S. Owada
The University of Tokyo, Tokyo, Japan
S. Matsubara, Y. Okayasu, T. Togashi
JASRI/SPring-8, Hyogo, Japan
T. Matsukawa, H. Minamide
RIKEN ASI, Sendai, Miyagi, Japan
E. Takahashi
RIKEN, Saitama, Japan

Non-destructive, shot-by-shot real-time monitors have been developed to measure 3D bunch charge distribution (BCD). This 3D monitor has been developed to monitor 3D overlapping electron bunches and higher harmonic generation (HH) pulses in a seeded VUV-FEL. This ambitious monitor is based on an Electro-Optic (EO) multiple sampling technique in a manner of spectral decoding that is non-destructive and enables real-time measurements of the longitudinal and transverse BCD. This monitor was materialized in simultaneously probing eight EO crystals that surround the electron beam axis with a radial polarized and hollow EO-probe laser pulse. In 2009, the concept of 3D-BCD monitor was verified through electron bunch measurements at SPring-8. The further target of the temporal resolution is ~30 fs (FWHM), utilizing an organic EO crystal (DAST) instead of conventional inorganic EO crystals (ZnTe, GaP, etc.) The EO-sampling with DAST crystal is expected to measure a bunch length less than 30 fs (FWHM). In 2011, the first bunch measurement with an organic EO crystal (DAST) was successfully demonstrated in the VUV-FEL accelerator at SPring-8.

TUPB081

Beam Diagnostics Development for Triumf E-Linac

target, TRIUMF, diagnostics, pick-up

660

V.A. Verzilov, P.S. Birney, D.P. Cameron, J.V. Holek, S.Y. Kajioka, S. Kellogg, M. Lenckowski, M. Minato, W.R. Rawnsley
TRIUMF, Vancouver, Canada
J.M. Abernathy, D. Karlen, D.W. Storey
Victoria University, Victoria, B.C., Canada

TRIUMF laboratory is currently in a phase of the construction of a new superconducting 50 MeV 10 mA cw electron linac (e-linac) to drive photo-fission based rare radioactive isotope beam (RIB) production. The project imposes certain technical challenges on various accelerator systems including beam diagnostics. In the first place these are a high beam power and strongly varying operating modes ranging from very short beam pulses to the cw regime. A number of development projects have been started to construct the diagnostics instrumentation required for commissioning and operation of the facility. The paper reports the present status of the projects along with measurement results obtained at the test facility which produced the first beam in Fall of 2011.

WE1A01

ERL-Based Light Source Challenges

gun, linac, laser, emittance

714

Y. Kobayashi
KEK, Ibaraki, Japan

The challenges of the design and technology for the future Energy Recovery Liancs will be reviewed: electron sources, injector, SCRF cavities and cryomodules, commissioning.

WE1A05

Linac-Based Laser Compton Scattering X-Ray and Gamma-Ray Sources

photon, laser, linac, brightness

734

R. Hajima
JAEA, Ibaraki-ken, Japan

Laser Compton scattering (LCS) light sources can provide high-energy photons from keV to MeV range. Many research and development projects of linac-based LCS sources are carried on. For the photon energies of tens keV, linac-based LCS sources realize laboratory-size X-ray sources, of which performance can be comparable to synchrotron light sources. Linac-based LCS also realizes unprecedented gamma-ray sources with better monochromaticity than ring-based LCS sources. This talk will review linac-based LCS source in the world.

Slides WE1A05 [2.881 MB]

TH1A03

Superconducting Spoke Cavities for Electron and High-Velocity Proton Linacs

cavity, linac, impedance, SRF

758

J.R. Delayen
ODU, Norfolk, Virginia, USA

Spoke resonantors are currently under development for many proton machines but these structures are also considered for high beta electron linacs as well. These structures compare well to traditional elliptical cavities.

Slides TH1A03 [3.570 MB]

TH2A004

Computational Model Analysis for Experimental Observation of Optical Current Noise Suppression Below the Shot-noise Limit

plasma, linac, simulation, beam-transport

783

A. Gover
University of Tel-Aviv, Faculty of Engineering, Tel-Aviv, Israel
A. Nause
University of Tel Aviv, Tel Aviv, Israel

Funding: We acknowledge support of the Israel Science Foundation grant
We report first demonstration of optical frequency current shot-noise suppression in a relativistic e-beam. This process is made possible by collective Coulomb interaction between the electrons of a cold intense beam during beam drift, and is essentially a process of longitudinal beam-plasma oscillation.[1] Suppression of beam current noise below the classical “shot-noise” level has been known in the microwave tubes art [2]. This is the first time that it is demonstrated in the optical regime. We predict that the scheme can be extended to the XUV and possibly to shorter wavelengths with further development of technology. The fundamental current shot-noise determines the level of incoherent spontaneous radiation emission from electron-beam optical radiation sources and SASE-FELs [3]. Suppressing shot-noise would make it possible to attain spontaneous emission sub-radiance [4] and surpass the classical coherence limits of seed-injected FELs. The effect was demonstrated by measuring sub-linear growth as a function of current of the OTR Radiation. This finding indicates that the beam charge homogenizes due to the collective interaction, and its distribution becomes sub-Poissonian.
[1] A. Gover, E. Dyunin, PRL, 102, 154801, 2009
[2] H. Haus, N. Robinson, Proc. IRE, 43, 981 (1955)
[3] P. Emma, et al , Nature Photonics 4, 641 (2010)
[4] A. Dicke, Phys. Rev. 93, 99 (1954)

TH3A02

The 12 GeV Energy Upgrade at Jefferson Laboratory

cryomodule, linac, cavity, collider

792

F.C. Pilat
JLAB, Newport News, Virginia, USA

Two new cryomodules and an extensive upgrade of the bending magnets at Jefferson Lab has been recently completed in preparation for the full energy upgrade in about one year.

Slides TH3A02 [3.482 MB]

TH3A03

ERL-Based Lepton-Hadron Colliders: eRHIC and LHeC

linac, hadron, ion, proton

797

F. Zimmermann
CERN, Geneva, Switzerland

This talk will review hadron-ERL collider projects. The LHeC is a plan to collide the LHC beam with electrons or positrons. One scheme for this facility is based on a superconducting recirculating linac with energy recovery. The electron hadron collider eRHIC will collide polarized and unpolarized electrons with a current of 50 mA and energy in the range of 5 GeV to 30 GeV with hadron beams, including heavy ions or polarized light ions of the RHIC storage ring. The electron beam will be generated in an energy recovery linac contained inside the RHIC tunnel, comprising six passes through two linac section of about 2.5 GeV each.

Slides TH3A03 [3.286 MB]

TH3A04

Plasmas, Dielectrics and the Ultrafast: First Science and Operational Experience at FACET

plasma, radiation, linac, acceleration

802

C.I. Clarke, E. Adli, S. Corde, F.-J. Decker, R.J. England, R.A. Erickson, A.S. Fisher, S.J. Gessner, C. Hast, M.J. Hogan, S.Z. Li, N. Lipkowitz, M.D. Litos, Y. Nosochkov, J.T. Seeman, J. Sheppard, I. Tudosa, G.R. White, U. Wienands, M. Woodley, Z. Wu, G. Yocky
SLAC, Menlo Park, California, USA
C.E. Clayton, C. Joshi, W. Lu, K.A. Marsh, N. Vafaei
UCLA, Los Angeles, California, USA

Funding: Work supported by the U.S. Department of Energy under contract number DE-AC02-76SF00515.
FACET (Facility for Advanced Accelerator and Experimental Tests) is an accelerator R&D test facility that has been recently constructed at SLAC National Accelerator Laboratory. The facility provides 20 GeV, 3 nC electron beams, short (20 um) bunches and small (20 um wide) spot sizes, producing uniquely high power beams. FACET supports studies from many fields but in particular those of Plasma Wakefield Acceleration and Dielectric Wakefield Acceleration. FACET is also a source of THz radiation for material studies. We present the FACET design, initial operating experience and first science from the facility.

Slides TH3A04 [3.091 MB]

THPLB11

Experimental and Simulation Study of the Long-path-length Dynamics of a Space-charge-dominated Bunch

simulation, space-charge, emittance, focusing

834

I. Haber, B.L. Beaudoin, S. Bernal, R.A. Kishek, T.W. Koeth, Y. Mo
UMD, College Park, Maryland, USA

Funding: Work supported by the United States Department of Energy and the Office of Naval Research.
The University of Maryland Electron Ring (UMER) is a low-energy (10 keV) electron facility built to study, on a scaled machine, the long-propagation-length evolution of a space-charge-dominated beam. Though constructed in a ring geometry to achieve a long path length at modest cost, UMER has observed important space-charge physics directly relevant to linear machines. Examples will be presented that emphasize studies of the longitudinal dynamics and comparisons to axisymmetric simulations. The detailed agreement obtained between simulation and experiment will be presented as evidence that the longitudinal physics observed is not strongly influenced by the ring geometry. Novel phenomena such as soliton formation, unimpeded bunch-end interpenetration, and an instability that occurs after this interpenetration, will be discussed.

THPB061

Experimental and Simulation Study of the Long-path-length Dynamics of a Space-charge-dominated Bunch

simulation, space-charge, emittance, focusing

978

I. Haber, B.L. Beaudoin, S. Bernal, R.A. Kishek, T.W. Koeth, Y. Mo
UMD, College Park, Maryland, USA

Funding: Work supported by the United States Department of Energy and the Office of Naval Research.
The University of Maryland Electron Ring (UMER) is a low-energy (10 keV) electron facility built to study, on a scaled machine, the long-propagation-length evolution of a space-charge-dominated beam. Though constructed in a ring geometry to achieve a long path length at modest cost, UMER has observed important space-charge physics directly relevant to linear machines. Examples will be presented that emphasize studies of the longitudinal dynamics and comparisons to axisymmetric simulations. The detailed agreement obtained between simulation and experiment will be presented as evidence that the longitudinal physics observed is not strongly influenced by the ring geometry. Novel phenomena such as soliton formation, unimpeded bunch-end interpenetration, and an instability that occurs after this interpenetration, will be discussed.

THPB063

Simulated Performance of the CARIBU EBIS Charge Breeder Transport Line

ion, simulation, emittance, diagnostics

984

C. Dickerson, S.A. Kondrashev, B. Mustapha, P.N. Ostroumov
ANL, Argonne, USA

Funding: This work is supported by the U.S. Department of Energy, Office of Nuclear Physics, under contract number DE-AC02-06CH11357.
An Electron Beam Ion Source (EBIS) has been designed and is being built to charge breed ions from the CAlifornium Rare Isotope Breeder Upgrade (CARIBU) for post acceleration in the Argonne Tandem Linear Accelerator System (ATLAS). The calculated transverse acceptance of the EBIS charge breeder can approach the emittance of the injected ion beam, so beam distortion during transport could lead to incomplete injection and a decrease in the overall system efficiency. The beam quality can be maintained for simulations of the transport line using the ideal ion beam parameters. This paper reports the results of the electrostatic and ion beam transport simulations used to minimize the ion beam distortions by optimizing component designs and configurations.

THPB064

Beam Dynamics Tools for Linacs Design

simulation, beam-loading, linac, synchrotron

987

A.S. Setty
THALES, Colombes, France

In the last 25 years, we have been using our in house 3D code PRODYN * for electron beam simulations. We have also been using our in house code SECTION for the design of the travelling wave accelerating structures and the beam loading compensation. PRODYN follows in time, the most complicated electron trajectories with relativistic space-charge effects. This code includes backward as well as forwards movements. This paper will describe those two codes and will give some simulations and measurements results.
* D. Tronc and A. Setty, Electrons RF auto-focusing and capture in bunchers, Linear Accelerator Conference 1988, Virginia.

THPB074

RF Photoinjector and Radiating Structure for High-power THz Radiation Source

radiation, coupling, vacuum, impedance

1005

S.M. Polozov, T.V. Bondarenko
MEPhI, Moscow, Russia
Y.A. Bashmakov
LPI, Moscow, Russia

Sources of high-power electromagnetic radiation in THz band are becoming promising as a new method of a low activation introscopy. Research and development of accelerating RF photoinjector and radiating system for THz radiation source are reported. The photoinjector is based on disk loaded waveguide (DLW). Two different designs of accelerating structures were modeled: widespread 1.6 cell of DLW structure and travelling wave resonator structure. The resonant models of these structures and the structures with power ports were designed. Electrodynamics characteristics and electric field distribution for all models were acquired. Results of picoseconds photoelectron beam dynamics in modeled structures are reported. Design of decelerating structures exciting Cherenkov radiation are based on corrugated metal channel and metal channel coated with dielectric. Analysis of radiation intensity and frequency band are presented.

THPB089

Magnetic Characterization of the Phase Shifter Prototypes Built by CIEMAT for E-XFEL

undulator, free-electron-laser, laser, FEL

1029

I. Moya, J. Calero, J.M. Cela-Ruiz, L. García-Tabarés, A. Guirao, J.L. Gutiérrez, L.M. Martinez, T. Martínez de Alvaro, E. Molina Marinas, L. Sanchez, S. Sanz, F. Toral, C. Vázquez, J.G.S. de la Gama
CIEMAT, Madrid, Spain
J. Campmany, J. Marcos, V. Massana
CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain

Funding: Work partially supported by Spanish Ministry of Science and Innovation under SEI Resolution on 17-September-2009 and project ref. AIC-2010-A-000524
The European X-ray Free Electron Laser (E-XFEL) will be based on a 10 to 17.5 GeV electron linac that will be used in the undulator system to obtain ultra-brilliant X-ray flashes from 0.1 to 6 nanometres for experimentation. The undulator system is formed by undulators and intersections between them, where a quadrupole on top of a precision mover, a beam position monitor, two air coils and a phase shifter are allocated. The function of the phase shifter is to adjust the phase of the electron beam and the radiation when they enter in an undulator according to the different beam energies and wavelengths. CIEMAT is working on the development of the phase shifters, as part of the Spanish in-kind contribution to the E-XFEL project. Several problems reported elsewhere were detected in the first prototype, which did not fulfil the first field integral specification. This paper describes the magnetic measurements realized on the second and third prototypes in the test bench at CELLS, together with the tuning process to decrease the field integral dependence with gap.

THPB092

Recent Improvements in SPring-8 Linac for Early Recovery from Beam Interruption

klystron, gun, linac, power-supply

1035

S. Suzuki, T. Asaka, H. Dewa, H. Hanaki, T. Kobayashi, T. Magome, A. Mizuno, T. Taniuchi, H. Tomizawa, K. Yanagida
JASRI/SPring-8, Hyogo-ken, Japan

The 1GeV SPring-8 linac is an injector for the SPring-8 synchrotron radiation storage ring with 8GeV booster synchrotron. In recent years, backup systems were installed to eliminate long-time interruption of the beam injections: The main gun system is usually operated, and the second gun is always pre-heated and can inject electron beams into a buncher section with an interval of several minutes in case the main gun failed. The first klystron, that feeds RF powers to the buncher system and the downstream klystrons, can be relieved by the next klystron with an interval of about 20 minutes by switching the waveguide circuit. When one of the eleven working klystrons faults, one of standby klystrons, which are kept for hot spares on line, is automatically activated to accelerate beams instead of the failed one without beam interruption. The total downtime in FY2012 was 0.12% in top-up operation user time. The averaged fault frequency was 0.2 times per day.

THPB095

Designing of a Phase-mask-type Laser Driven Dielectric Accelerator for Radiobiology

laser, acceleration, simulation, vacuum

1041

K. Koyama
UTNL, Ibaraki, Japan
A. Aimidura, M. Uesaka
The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan
Y. Matsumura
University of Tokyo, Tokyo, Japan
T. Natsui, M. Yoshida
KEK, Ibaraki, Japan

Funding: This work is supported by KAKENHI, Grant-in-Aid for Scientific Research (C) 24510120
In order to estimate the health risk of a low radiation dose, basic processes of the radiobiology should be clarified by shooting a DNA using a spatially and temporary defined particle beam or X-ray. A suitable beam size is as small as a resolving power of an optical microscope of a few hundred nanometers. Photonic crystal accelerators (PCA) are capable of delivering nm-beams of sub-fs pulses because the characteristic length and frequency of PCAs are on the order of the laser light. Since the phase-mask type accelerator has a simpler structure than other types of PCAs, we are designing a phase-mask type laser driven dielectric accelerator. By adopting an unbalanced length of pillar and ditch (grating) of 4:1, a standing wave like acceleration field is produced in a acceleration channel. A pillar height and initial speed of injected electron are determined by analytically. The maximum acceleration gradient of 2 GeV/m is estimated. The required laser power is roughly estimated to be 6.5 GW. The simulation using CST-code also shows similar values to accelerate electrons by the phase-mask type accelerator.

THPB096

High-power Sources of RF Radiation Driven by Periodic Laser Pulses

laser, cavity, radiation, klystron

1044

S.V. Kuzikov, A.V. Savilov
IAP/RAS, Nizhny Novgorod, Russia
S.V. Kuzikov
Omega-P, Inc., New Haven, USA

Funding: Supported in part by DoE USA.
A fast, periodic modulation of electron RF sources can be carried out in a form of Q-factor switching by means of fast RF switches, or in a form of I-switching by means of the bunched electron beam. If modulation frequency equals to time which is necessary for RF radiation to travel along the cavity and to come back, the RF oscillator can produce periodic, giant, short pulses which are desirable for many applications in order to avoid a breakdown. The produced RF pulses are phase and frequency locked by modulation shape. The mentioned effects of the phase and frequency locking remain also possible for RF sources operated in a single-mode regime. In last case the modulation frequency should be close to natural single-mode oscillation frequency. For example, one might control operation of a BWO by means of a small periodical modulation of the electron voltage in a drift section in-between a cathode and the corrugated interaction section. The necessary voltage modulation can be provided by means of a DC generator those voltage due to a photoconductivity is externally modulated with definite frequency by laser which irradiates GaAs isolator inserted in-between the electrodes.

FR1A01

Heavy Ion Strippers

ion, plasma, heavy-ion, cyclotron

1050

F. Marti
FRIB, East Lansing, Michigan, USA

Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661
Stripping of high current heavy ion beams is a key technology for future accelerator as FAIR (Germany) and FRIB (USA) and current ones as RIBF (RIKEN, Japan). A small change in the peak charge state produced at the stripper could require a significant expense in additional accelerating stages to obtain the required final energy. The main challenges are the thermal effects due to the high power deposition (~ 50 kW/mm³) and the radiation damage due to the high energy deposition. The effects of heavy ion beams are quite different from proton beams because of the much shorter range in matter. We will present an overview talk considering charge stripping devices like carbon foils and gas cells used worldwide as well as the current research efforts on plasma stripping, liquid metal strippers, etc. The advantages and disadvantages of the different options will be presented.

Slides FR1A01 [4.174 MB]