IPAC2014 - List of Keywords (acceleration)

Paper	Title	Other Keywords	Page
MOPRO003	Towards Stable Acceleration in Linacs	klystron, bunching, electron, linac	65
	A. Dubrovskiy Private Address, Geneve, Switzerland
	Ultra-stable and -reproducible high-energy particle beams with short bunches are needed in novel linear accelerators and, in particular, in the Compact Linear Collider CLIC. A passive beam phase stabilization system based on a bunch compression with a negative transfer matrix element R56 and acceleration at a positive off-crest phase is proposed. The motivation and expected advantages of the proposed scheme are outlined.
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MOPRO016	NANOPERM® Broad Band Magnetic Alloy Cores for Synchrotron RF Systems	synchrotron, target, damping, background	95
	T. Trupp MAGNETEC GmbH, Langenselbold, Germany
	Recent developments in synchrotron acceleration systems show a demand for broadband MA (Magnetic Alloy) magnetic core loaded cavities with a high field gradient. For many facilities e.g. GSI, CoSY, J-Parc limited installation lengths requires high gradients in the region of 40kV/m. Both requirements rule out ferrite materials due to the lower maximum excitation levels and high Q-value. This request can solely be met by Finemet type cores like NANOPERM® produced by MAGNETEC. In this paper, the statistics of 22 huge cores made of NANOPERM® and measured high frequency properties are shown under free-space (FS) condition and compared with the theoretical expectation.
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MOPRO115	A Low Energy Electron-Scrapersystem for the S-DALINAC Injector	electron, linac, controls, target	366
	L.E. Jürgensen, T. Bahlo, C. Burandt, F. Hug, T. Kürzeder, N. Pietralla, T. Schösser, C. Ungethüm TU Darmstadt, Darmstadt, Germany
	Funding: Work supported by DFG through SFB 634 The S-DALINAC is the superconducting linear accelerator of the Institut für Kernphysik at Technische Universität Darmstadt. It delivers an electron beam with energies up to 130 MeV. In order to improve the energy spread and the energy stability of the beam for further acceleration a new scrapersystem has been developed and installed between the 10 MeV injector and the main linac. The system was designed to ensure an energy spread of dE < 10^-03. After installation several tests have taken place, the results will be presented in this work.
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MOPME035	Current Status of the GPU-Accelerated ELEGANT	GPU, operation, simulation, linac	454
	I.V. Pogorelov, K.M. Amyx, J.R. King Tech-X, Boulder, Colorado, USA M. Borland, R. Soliday ANL, Argonne, Ilinois, USA
	Funding: Work supported by the DOE Office of Science, Office of Basic Energy Sciences grant No. DE-SC0004585, and in part by Tech-X Corporation. Efficient implementation of general-purpose particle tracking on GPUs can result in significant performance benefits to large-scale tracking simulations. This presentation is an update on the current status of our work on accelerating Argonne National Lab’s particle accelerator simulation code ELEGANT using CUDA-enabled GPU. We summarize the performance of beamline elements ported to GPU, and discuss optimization techniques for some important collective effects kernels, in particular our methods of avoiding costly thread contention. We also present preliminary results of a scaling study of the GPU-accelerated version of the code.
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MOPME051	Turbo Generators for Powering the HV-solenoids at the HESR Electron Cooler	solenoid, electron, high-voltage, power-supply	492
	A. Hofmann, K. Aulenbacher, M.W. Bruker, J. Dietrich, T. Weilbach HIM, Mainz, Germany M.I. Bryzgunov, A.P. Denisov, V.M. Panasyuk, V.V. Parkhomchuk, V.B. Reva BINP SB RAS, Novosibirsk, Russia
	New experiments at the planned 'High Energy Storage Ring' (HESR) require magnetised electron cooling. One of the challenges is the powering of the HV-solenoids, because they are located on HV-sections, which sit on an electrical potential inside a high voltage vessel. We discuss a Multi-MV system where the solenoids are powered by a series of cascade transformers which are in turn supplied by turbogenerators. The usage of SF6 as turbine fluid is desirable from the viewpoint of operational stability and may also lead to energy efficient operation of the turboexpanders since a Organic Rankine-cycle (so-called ORC-process) may be used instead of electrically driven compressors. The paper gives an overview of the turbo generator and ORC project: an introduction, a status report and a road map will be given.
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MOPME068	SiC-JFET Switching Power Supply toward for Induction Ring Accelerators	ion, extraction, induction, injection	523
	K. Okamura, K. Takayama, M. Wake, T. Yoshimoto KEK, Ibaraki, Japan R. Sasaki, K. Takaki Iwate university, Morioka, Iwate, Japan K. Takayama, T. Yoshimoto TIT, Yokohama, Japan F. Tamura Nagaoka University of Technology, Nagaoka, Niigata, Japan
	Funding: Japan Science and Technology Agency Grant-In Aid for Scientific Research(s) (KAKENHI No. 24310077) A new induction synchrotron system using an induction cell has been developed and constructed at KEK. In that system, the switching power supply is one of the key devices that realize digital acceleration. The requirements of the switching power supply are high voltage (2 kV) and high repetition frequency (1 MHz). In the present system, we used series connected MOSFETs as the switching device. However, series connection gives large complexity and less reliability. Among various switching devices, a SiC-JFET should be a promising candidate because it has ultrafast switching speed and high voltage blocking capability. We have developed a new and original SiC-JFET switching device and a compact switching power supply employing this switching element. Now it is integrated into the induction acceleration system for the KEK-DA. Furthermore we have started development of the next generation of SiC package, which has higher voltage capability (2.4 kV) and 2 in 1 module construction. At the conference, the first experimental demonstration of heavy ion acceleration utilizing the SiC-JFET and the design status of the new device package will be presented. T. Iwashita et al., Phys. Rev. ST-AB 14, 071302 (2011). ** K. Okamura et al., “A Compact Switching Power Supply Utilizing SiC-JFET for The Digital Accelerator ”, in Proc. of IPAC’12, pp 3677-3679.
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MOPRI072	Simulation Study of Heavy Ion Beam Injection and Acceleration in the HESR for Internal Target Experiments with Cooling	target, ion, experiment, cavity	768
	H. Stockhorst, B. Lorentz, R. Maier, D. Prasuhn, R. Stassen FZJ, Jülich, Germany T. Katayama Nihon University, Narashino, Chiba, Japan
	Recently, the feature of ion beam injection, storage and acceleration assisted by a barrier bucket and cooling has been investigated in the High Energy Storage Ring HESR at the new facility FAIR which will be built at the GSI Darmstadt. A bare uranium beam is injected from the collector ring CR into the HESR at 740 MeV/u. The simulation studies are now improved to include different injection schemes applying either the barrier cavity or the h = 1 cavity in the HESR. It is outlined how the new 2.5 MeV electron cooler at COSY Jülich or stochastic cooling can support the injection mechanism. The beam preparation for an internal target experiment with cooling is outlined. The acceleration of the ion beam is extended to 5 GeV/u under the mandatory condition of the available cavity voltages and the maximum magnetic field ramp rate in the HESR. The flexibility of the HESR ring lattice is utilized to avoid transition energy crossing during ramping up to 5 GeV/u and to adjust the rings’ frequency slip factor for optimal stochastic cooling. The cooling simulations include the beam-target interaction due to a hydrogen target. H. Stockhorst et al., MOPEA018, IPAC13
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MOPRI074	Conceptual Project Relativistic Electron Cooler for FAIR/HESR	electron, proton, high-voltage, cathode	774
	V.V. Parkhomchuk, M.I. Bryzgunov, A.P. Denisov, V.M. Panasiuk, V.B. Reva BINP SB RAS, Novosibirsk, Russia K. Aulenbacher, J. Dietrich HIM, Mainz, Germany V. Kamerdzhiev FZJ, Jülich, Germany
	To develop a 4 MeV relativistic electron cooling system for the HESR storage ring, which is part of the future GSI facility FAIR, is proposed to further boost the luminosity even with strong heating effects of high-density internal targets. In addition the upgrade to 8 MeV of the relativistic electron cooler is essential for the future Electron Nucleon Collider (ENC@FAIR) project. The basic feature of the design are the power for magnet field coils at accelerating and decelerating column is generated by turbines (one option under investigation in this research group) operated on SF6 gas under pressure
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MOPRI076	Simulation of Dynamics in Ultra-compact Isochronous Medium Energy Racetrack FFAGs	cyclotron, focusing, dynamic-aperture, lattice	780
	R. Appleby, J.M. Garland, H.L. Owen, S.C. Tygier UMAN, Manchester, United Kingdom K.M. Hock Cockcroft Institute, Warrington, Cheshire, United Kingdom C. Johnstone PAC, Batavia, Illinois, USA
	Funding: Research supported by STFC grant number ST/K002503/1 "Racetrack FFAGs for medical, PRISM and energy applications". The FFAG (Fixed-Field Alternating-gradient) accelerator is a class of accelerators that comprises the best features of the cyclotron and the synchrotron, combining fixed magnetic fields with strong focusing gradients for optimal stable, low-loss operation. Here, a new type of medium-energy 1-GeV isochronous (CW) FFAG has been developed in a racetrack layout that supports two opposing synchrotron-like straights, permitting both high-gradient RF modules and efficient injection and extraction in a highly compact footprint. In this paper we present beam dynamic simulations for this compact racetrack FFAG, and compare the differences between an equivalent circular and a racetrack configuration. A comparison of the FFAG dynamics with the 800-MeV (Daeδalus) cyclotron is briefly presented.
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MOPRI080	Measurement of Beam Phase using Phase Probe at the NIRS-930 Cyclotron	pick-up, extraction, cyclotron, septum	794
	S. Hojo, K. Katagiri, M. Nakao, A. Noda, K. Noda, A. Sugiura NIRS, Chiba-shi, Japan T. Honma, A.K. Komiyama, T. Okada, Y. Takahashi AEC, Chiba, Japan
	The NIRS-930 cyclotron of the National Institute of Radiological Sciences (NIRS) has been used for production of short-lived radio-pharmaceuticals for PET, research of physics, developments of particle detectors in space, and so on. The NIRS-930 has twelve trim coils for generation of the isochronous fields. Until recently, currents of the twelve trim coils had been adjusted only by monitoring the beam intensity. In order to exactly produce the isochronous fields, a phase probe has been installed in the NIRS-930. Recent results of beam tests using the phase probe will be presented in the present work.
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MOPRI093	Technical Design of Normal Conducting Re-buncher in the MEBT for Rare Isotope Science Project	cavity, rfq, ion, operation	830
	H.J. Kim, W.K. Han, I.S. Hong, D. Jeon IBS, Daejeon, Republic of Korea
	Funding: This work was supported by the RISP of Institute for Basic Science funded by Ministry of Science, ICT and Future Planning and National Research Foundation of Korea.(2011-0032011) The front-end system of RISP heavy-ion accelerator(RAON) consists of an electron cyclotron resonance ion source, a low energy beam transport line, a radio frequency quadrupole accelerator and a medium energy beam transport(MEBT) line. The MEBT system, which consists of quadrupole magnets, three normal-conducting re-bunchers and diagnostic devices, is installed between the RFQ accelerator and the superconducting linac(SCL). The three normal-conducting re-bunchers are used to minimize the growths of the longitudinal emittance and to manipulate the particle distribution on longitudinal phase space for beam transportation in SCL. Several combination of the number of cavities was examined, and the quarter wave resonator(QWR) type re-buncher was chosen for MEBT line in RAON. The QWR cavity has a frequency of 81.25 MHz, a maximum electric field of 2.53 MV/m on the cavity surface with an electric field of 1 MV/m on the beam axis, a geometrical beta factor of 0.032 and an effective length of 24 cm. In this presentation, I will present the results of baseline design for electro-magnetic field analysis and mechanical design for stress analysis, thermal stress analysis and cooling channel.
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MOPRI103	Longitudinal Bunch Shortening for the Laser Stripping Project	laser, cavity, focusing, linac	861
	T.V. Gorlov, A.V. Aleksandrov, S.M. Cousineau, V.V. Danilov, Y. Liu, M.A. Plum ORNL, Oak Ridge, Tennessee, USA
	Funding: This work is funded by the U.S. DOE under grant number DE-FG02-13ER41967, and by the U.S. DOE under contract number DE-AC05-00OR22725 with UT-Battelle Corporation. Realization of high efficiency laser stripping at the SNS accelerator needs good longitudinal overlap between H⁻ bunch and laser pulse. The default H⁻ bunch length at the interaction point is 5 times bigger than needed in order to achieve 90% stripping efficiency. Theoretical and experimental studies of longitudinal H⁻ bunch shortening are presented in this paper.
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TUYB01	Vertical Orbit-excursion Fixed Field Alternating Gradient Accelerators (V-FFAGs) and 3D Cyclotrons	cyclotron, closed-orbit, quadrupole, proton	956
	S.J. Brooks BNL, Upton, Long Island, New York, USA
	FFAGs with vertical orbit excursion (VFFAGs) provide a promising alternative design for rings with fixed-field (e.g. superconducting) magnets. They have a vertical magnetic field component that increases with height in the vertical aperture, yielding a skew quadrupole focussing structure. Scaling type VFFAGs have fixed tunes and no intrinsic limitation on momentum range; they are also isochronous in the ultra-relativistic limit. Extending isochronism to lower velocities requires a slanted orbit excursion: a three-dimensional analogue of a spiral sector cyclotron from 40 to 1500MeV is developed, which is flat at low energies and acquires a slope as the protons become relativistic. This provides more stable tunes than a comparable planar cyclotron. Such machines are promising future candidates for nuclear transmutation using high average power CW beams at ~GeV energies.
	Slides TUYB01 [16.187 MB]
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TUOBB01	Accelerator Physics Challenges towards a Plasma Accelerator with Usable Beam Quality	plasma, electron, laser, wakefield	961
	R.W. Aßmann, J. Grebenyuk DESY, Hamburg, Germany
	Enormous progress in compact plasma accelerators has been demonstrated over the recent years in various experiments. These experiments rely on high power, pulsed lasers or short electron bunches to excite ultra-strong wakefields in plasmas. Accelerating gradients have reached several 10 GV/m up to 100 GV/m and the absolute energy gain of electron beams is in the regime of several GeV to 30 GeV. The principle and potential of plasma accelerators has been proven impressively and performance parameters are steadily improving. It is noted that particle accelerators are powerful tools that are ultimately justified by their applications in science, medicine or industry. The demonstration of useable beam quality and a realistic use case remains to be achieved for plasma accelerators. The accelerator physics challenges to arrive at this goal are analyzed and discussed.
	Slides TUOBB01 [12.407 MB]
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TUPRO040	High Bandwidth Closed Orbit Control for a Fast Ramping Electron Accelerator	closed-orbit, resonance, electron, polarization	1111
	J.-P. Thiry, A. Dieckmann, F. Frommberger, W. Hillert, J.F. Schmidt ELSA, Bonn, Germany
	ELSA is a fast ramping stretcher ring capable of acceleration and storage of polarized electrons with energies up to 3.2 GeV. To preserve the initial degree of polarization, the acceleration is performed by a fast energy ramp with a maximum ramping speed of 6 GeV/s. During acceleration especially the vertical orbit needs to be continuously corrected so that the vertical rms deviation does not exceed 50 μm at any time. In order to compensate the so called integer resonances, which occur at certain energies, the orbit correction system further needs to provide additional, empirically determined, harmonic field distributions. A successful application of these combined correction measures requires a considerably high bandwidth of up to some 100 Hz. In our contribution we will have a closer look at the performance and the acquired bandwidth of the correction system.
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TUPRO074	Emittance Growth due to Multiple Coulomb Scattering in a Linear Collider based on Plasma Wakefield Acceleration	scattering, plasma, emittance, electron	1211
	Ö. Mete, K. Hanahoe, G.X. Xia UMAN, Manchester, United Kingdom O. Karamyshev, C.P. Welsch The University of Liverpool, Liverpool, United Kingdom M. Labiche STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom M. Wing UCL, London, United Kingdom
	Alternative acceleration technologies are currently under development for cost-effective, robust, compact and efficient solutions. One such technology is plasma wakefield accel- eration, driven by either a charged particle or laser beam. However, the potential issues must be studied in detail. In this paper, the emittance growth of the witness beam through elastic scattering from gaseous media is derived. The model is compared with the numerical studies.
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TUPRO093	Numerical Study of Intrinsic Ripples in J-PARC Main-ring Magnets	simulation, damping, operation, synchrotron	1256
	Y. Shirakabe, A.Y. Molodozhentsev, M. Muto KEK, Tsukuba, Japan
	Beam ripples are one of the critical problems in high power proton synchrotrons. Magnet field ripples are considered as a main origin of the beam ripples among various possible sources. Although magnet power supply ripples are generally treated as the dominating ripple source, the load circuit parameters of the magnets and their interconnections are also playing critical roles in defining the ripple amplitudes and frequencies. In this viewpoint, the magnet power supplies are treated as simplified current sources, and the ripples generated in the circuit systems are investigated both in analytical and numerical ways. One of the findings in this direction of investigation is the existence of intrinsic ripples. The intrinsic ripples occur inevitably in the synchrotron magnets, no matter how the power supplies are producing idealistic current ramp patterns. Their amplitudes are defined by the circuit parameters such as inductance and capacitance, and the ramp parameters such as ramp rates. Some of the analytical mechanisms in generating the magnet field ripples are presented as well as the studied examples.
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TUPME031	Radiation Pressure Acceleration and Transport Methods	laser, plasma, simulation, target	1422
	P. Schmidt, O. Boine-Frankenheim TEMF, TU Darmstadt, Darmstadt, Germany O. Boine-Frankenheim, O. Boine-Frankenheim, I. Hofmann GSI, Darmstadt, Germany I. Hofmann HIJ, Jena, Germany I. Hofmann IAP, Frankfurt am Main, Germany
	Funding: HGS-HIRe for FAIR, HIC for FAIR, Technische Universität Darmstadt, FB 18 TEMF Several projects worldwide such as LIGHT at GSI focus on laser ion acceleration. With the development of new laser systems and advances in the target production a new acceleration mechanism has become of interest: The Radiation Pressure Acceleration (RPA). An ultra short high intense laser pulse hits a very thin foil target and the emerging plasma is ideally accelerated as one piece (light sail regime). The ions reach kinetic energies up to GeV and nearly solid body densities. In this work, the distribution and transport of a RPA plasma is studied. 1D and 2D PIC simulations (software: VSim) are carried out to obtain the phase space distribution of the plasma. The results are compared to fluid models (software: FiPy and USim). A reference model an RPA plasma is obtained which is then used for advanced transport studies. Transport mechanisms (active and passive) are studied, such asμlenses and foil stacks.
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TUPME033	Scaling of TNSA-accelerated Proton Beams with Laser Energy and Focal Spot Size	laser, target, proton, experiment	4093
	L. Obst, S. Kraft, J. Metzkes, U. Schramm, K. Zeil Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiation Physics, Dresden, Germany
	By focusing an ultra-short high-intensity laser pulse on a solid target, pulses of protons and other positively charged ions with energies of several 10 MeV per nucleon are generated. The properties of these particle beams such as their energy and absolute number are highly dependent on experimental conditions like laser and target parameters. In order to achieve principal comparability between different experimental campaigns at the Draco laser system at the Helmholtz-Zentrum Dresden-Rossendorf, a reference setup for the laser ion acceleration experiment was established. A configuration is sought in which proton beams of reproducible characteristics are generated. To ensure a high stability of the proton spectra, the application of longer focal length parabolas (f ~ 1000 mm) will be tested for this setup, according preparatory studies being presented in this paper.
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TUPME035	Design Study of the Laser-driven Dielectric Accelerator	laser, electron, simulation, focusing	1428
	K. Koyama, M. Yoshida KEK, Ibaraki, Japan Y. Matsumura University of Tokyo, Tokyo, Japan S. Otsuki The University of Tokyo, Tokyo, Japan M. Uesaka The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan
	Funding: This work was partly supported by KAKENHI, Grant-in-Aid for Scientific Research (C) 24510120. Laser driven dielectric accelerators (LDA) are vigorously studied in order to apply to various fields in recent years. Characteristics of the LDA output such as sub-micron diameter, atto-second bunch and high acceleration field are suitable for in-situ investigating the biological effects of low doses of radiation in a living cell. The output energy of 1 MeV is sufficient for sniping a cell nucleus or DNA. Although the electronic charge in the bunch is in the order of 10 fC, the tightly focused beam enable to cause a local damage in the cell. We have reported optimum structure parameters of dielectric in the nonrelativistic regime. The low acceleration efficiency of slow electrons by short laser pulses is the serious problem. The accelerator length, laser intensity, pulse width, and optical system must be adjusted to design the practical LDA. We present the design principle of the LDA for nonrelativistic electrons and present status of the pumping laser of us.
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TUPME036	Simulation Study on Electron Beam Acceleration using Coherent Cherenkov Radiation	electron, simulation, radiation, laser	1431
	K. Kan, M. Gohdo, T. Kondoh, K. Norizawa, I. Nozawa, A. Ogata, T. Toigawa, J. Yang, Y. Yoshida ISIR, Osaka, Japan M. Hangyo ILE Osaka, Suita, Japan R. Kuroda, H. Toyokawa AIST, Tsukuba, Ibaraki, Japan
	Beam diagnostics for electron bunch length using spectrum analysis of multimode terahertz (THz) -wave have been studied in ISIR, Osaka University. The multimode THz-wave was generated by coherent Cherenkov radiation (CCR)* using hollow dielectric tubes and femtosecond/picosecond electron bunches. In this study, numerical calculation of acceleration and deceleration of electron beam using multimode THz-wave was carried out. * K. Kan et al., Appl. Phys. Lett. 99, 231503 (2011). ** A. M. Cook et al., Phys. Rev. Lett. 103, 095003 (2009).
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TUPME037	Development on On-chip Radiation Source using Dielectric Laser Accelerator	laser, electron, radiation, simulation	1434
	S. Otsuki The University of Tokyo, Tokyo, Japan K. Koyama, M. Yoshida KEK, Ibaraki, Japan Y. Matsumura University of Tokyo, Tokyo, Japan S. Mima RIKEN, Japan M. Uesaka The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan
	Funding: This work was partly supported by KAKENHI, Grant-in-Aid for Scientific Research (C) 24510120. One of the state-of-the-art acceleration schemes, where high intensity laser pulses are modulated by dielectric grating structure such as quartz to accelerate charged particles, is dielectric laser acceleration (DLA). The difference of our DLA concept from other schemes is installation of a prism: the tilted wave-front in a prism shape refractive medium leads the suitable delay to match the phase advance of the electron beam. We plan to apply this method to build an on-chip radiation source which can hit and damage target elements of the cells. Such an application is useful in radiation biology, i.e., for investigation on bystander effects. The x-rays with small radius and adequate intensity required for this goal can be obtained using sub-micron beams from the small accelerating structure at high repetition rate (such as 50 kHz). In addition, the mass productivity of the DLA based on the consumer-grade laser and the photolithography has advantage compared to the conventional RF accelerator using high power klystrons. We will present field simulation and preliminary experimental results for demonstration on our concept of DLA. Demonstration of electron acceleration in a laser-driven dielectric microstructure, Nature 2013 ** Laser-Based Acceleration of Nonrelativistic Electrons at a Dielectric Structure, Phys. Rev. 2013
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TUPME040	Drive Beam Break-up Control and Practical Gradient Limitation in Collinear Dielectric Wakefield Accelerators	wakefield, simulation, linac, quadrupole	1443
	C. Li, W. Gai, J.G. Power, A. Zholents ANL, Argonne, Illinois, USA C.-J. Jing Euclid TechLabs, LLC, Solon, Ohio, USA C. Li, C.-X. Tang TUB, Beijing, People's Republic of China
	Dielectric wakefield accelerator (DWA) concept has gained significant attention for the need of the future large scale facilities. For a practical machine, one needs to overcome a major challenge for the DWA that is the efficient energy extraction and stable propagation at the same time for the drive beam. Typically, a slightly off axis beam become unstable in the dielectric channel due to transverse wakefield excitation, that could be controlled if a strong external alternating magnetic focusing channel applied at the same time. However, there is limitation on the practical magnetic field in the focusing channel (typically < 1 Tesla), thus imposing operating point for the DWA. In this article, we explore the operating point of the DWA for various structure frequencies and drive beam charge, particularly on the gradient and total acceleration distance, and provide guidance on the DWA design.
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TUPME042	Planned High-gradient Flat-beam-driven Dielectric Wakefield Experiments at the Fermilab’s Advanced Superconducting Test Accelerator	wakefield, emittance, experiment, controls	1451
	F. Lemery, D. Mihalcea, P. Piot Northern Illinois University, DeKalb, Illinois, USA P. Piot, J. Zhu Fermilab, Batavia, Illinois, USA J. Zhu CAEP/IFP, Mainyang, Sichuan, People's Republic of China
	In beam driven dielectric wakefield acceleration (DWA), high-gradient short-wavelength accelerating fields are generally achieved by employing dielectric-lined waveguides (DLWs) with small aperture which constraints the beam sizes. In this paper we investigate the possibility of using a low-energy (50-MeV) flat beams to induce high-gradient wakes in a slab-symmetric DLW. We demonstrate via numerical simulations the possibility to produce axial electric field with peak amplitude close to 0.5 GV/m. Our studies are carried out using the Fermilab's Advanced Superconducting Test Accelerator (ASTA) photoinjector beamline. We finally discuss a possible experiment that could be performed in the ASTA photoinjector and eventually at higher energies.
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TUPME043	Temporal Electron-bunch Shaping from a Photoinjector for Advanced Accelerator Applications	space-charge, laser, wakefield, gun	1454
	F. Lemery, P. Piot Northern Illinois University, DeKalb, Illinois, USA P. Piot Fermilab, Batavia, Illinois, USA
	Advanced-accelerator applications often require the production of bunches with shaped temporal distributions. An example of sought-after shape is a linearly-ramped current profile that can be improve the transformer ratio in beam-driven acceleration, or produce energy-modulated pulse for, e.g., the subsequent generation of THz radiation. Typically, such a shaping is achieved by manipulating ultra-relativistic electron bunches. In this contribution we discuss the possibility of shaping the bunch via photoemission and demonstrate using particle-in-cell simulations the production of MeV electron bunches with quasi-ramped current profile.
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TUPME045	Development of a High-Energy Short-pulse 5-μm Parametric Source for Dielectric Laser Acceleration	laser, detector, operation, optics	1460
	G. Xu, I. Jovanovic, S.F. Wandel Penn State University, University Park, Pennsylvania, USA
	A compact, high-peak-power 5-μm laser source with pulse duration of sub-100 fs has been designed and being constructed for pumping a dielectric photonic structure to produce an acceleration gradient of order GV/m in dielectric laser acceleration. Breakdown of dielectric structure induced by multiphoton ionization can be mitigated by adopting long wavelength driver laser. Since the dielectric structure scales with the laser wavelength, fabrication tolerances for dielectric structure are relaxed as well. The 5-μm laser source is based on two cascaded optical parametric amplifiers (OPA): a 2-μm BBO OPA with a mixed phase matching scheme is used as a pump source, and a type-I phase-matched ZGP OPA is designed to produce sub-mJ, <100 fs 5-μm laser pulses. The two-stage 2-μm OPA is pumped by a Ti:sapphire amplifier and produces pulse energy of ~2.2 mJ with a pulse duration of 42 fs (~6 optical cycles), and excellent pulse stability and beam quality. Preliminary result of ~50 μJ pulse energy at 5-μm is demonstrated by using single-stage ZGP OPA, and an improved two-stage OPA scheme for production of higher pulse energy at 5-μm is under development.
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TUPME052	Enhanced Laser Ion Acceleration based on Near-Critical Density Plasma Lens	plasma, laser, target, electron	1483
	Y.X. Geng, J.E. Chen, L.R.F. Li, Y.H. Li, Q. Liao, C. Lin, L.H.Y. Lu, Y.R. Lu, H. Wang, X.Q. Yan, Z.X. Yuan, S. Zhao, W.B. Zhao, Y.Y. Zhao, K. Zhu, B.Y. Zou PKU, Beijing, People's Republic of China
	The laser prepulse has large effect on ion acceleration driven by high power laser pulse. Recently, simulations show that with proper prepulse parameters, a near critical density pre-plasma can be generated in the front target. When the main laser pulse propagating in this pre-plasma, it can experience transverse Self-focusing, longitudinal profile steepening and prepluse cleaning at the same time, meaning its quality is spontaneously improved by this “plasma lens”.The effects can greatly improve the energy coupling efficiency of laser pulse into accelerated ions. A 3mJ Ti-Sapphire laser system has been built at PKU in order to experimentally study the pre-pulse effect on a solid target. Fluid simulation show that, after hundreds of picoseconds radiated with this laser pulse, the pre-plasma in front of the target will expand to near critical density with tens of micron scale length, which is suitable as a plasma lens to improve the ion acceleration. A laser interferometer system is built to measure the scale length and density evolution of plasma and the optimum condition of the pre-plasma has been searched using both Aluminum target and home-made DLC target. H.Y.Wang et al, Laser shaping of a relativistic intense, short Gaussian pulse by a plasma lens, PRL, 107,265002, 2011
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TUPME055	Room-temperature Burst-mode GHz and THz Pulse-train Photoinjector	electron, laser, cathode, bunching	1492
	F.H. Chao, C.H. Chen, K.Y. Huang, Y.-C. Huang, Y.C. Wang, M.H. Wu NTHU, Hsinchu, Taiwan P.J. Chou NSRRC, Hsinchu, Taiwan
	A photoinjector usually generates an electron pulse with few ps pulse duration repeating at 10-100 Hz. The low-pulse rate limits the data rate in a number of applications. Although high-repetition-rate operation is possible from a superconducting accelerator, the high cost and complexity of a superconducting system prevent it from being widely used. In this paper, we present our study toward a burst-mode GHz/THz pulse train photoinjector operating at room temperature. For the GHz operation mode, we self-develop a driver laser system, generating tens of laser pulses at 2.856 GHz in an adjustable 5-10 ns temporal envelope repeating at 10 Hz. Upon illuminating the photocathode with the driver laser, our S-band photoinjector (supported by Tsing Hua University, Beijing) is to generate a GHz electron pulse train with the same temporal structure as that of the driver laser pulses. For the THz operation mode, we illuminate the photocathode with two lasers, one being a typical UV gun-driver laser at 260 nm and the other being a mid-infrared laser at 100 THz. The UV laser induces photoemission and the infrared laser gates the emission current at 100 THz by virtue of the Schottky effect.
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TUPME056	Improving Ion and Electron Beam Characteristics within LA³NET	laser, electron, photon, simulation	1495
	C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom C.P. Welsch The University of Liverpool, Liverpool, United Kingdom
	Funding: This project has received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement no 289191. Lasers are widely used at accelerator and light source facilities for beam generation, acceleration and optimization. Research within LA³NET focuses on laser-based particle sources (photo injectors and laser ion sources), laser acceleration, and laser-based beam diagnostics. This project was recently selected as a ‘success story’ by the European Commission for its research achievements. This paper presents selected numerical and experimental results. From HZDR results of electron transport simulations in their new SRF gun II cavity, super-conductive solenoid and downstream accelerators are shown. The results from optimization studies into asymmetric grating structures obtained at the University of Liverpool are also presented, along with initial results from studies into novel diagnostics for high intensity proton beams at CERN and low energy electron beams at KIT. Finally, the events organized by the consortium to date and future plans are summarized.
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TUPME060	Simulation Analysis on Micro-Bunched Density Modulation from a Slit-Masked Chicane	simulation, electron, bunching, dipole	1509
	Y.-M. Shin, P. Piot, C.R. Prokop Northern Illinois University, DeKalb, Illinois, USA D.R. Broemmelsiek, E.R. Harms, A.H. Lumpkin, J. Ruan, J.C.T. Thangaraj Fermilab, Batavia, Illinois, USA
	Funding: This work was supported by the DOE contract No. DEAC02-07CH11359 to the Fermi Research Alliance LLC. Pre-bunching a beam at a resonance condition with an accelerating structure vastly improves performance of beam-driven accelerators and undulators since it enhances a beam-wave coupling. We plan to test a slit-mask micro-buncher at the chicane of Fermilab-ASTA 50 MeV beamline in the effort of advanced accelerator research. With the chicane design parameters (bending angle (alpha) of 18 degree, R56 ~ - 0.18 m, and bending radius of ~ 0.78 m), analytic model showed that a slit-mask with W (period) = 900 um and a (aperture width) = 300 um (30 % transparency) generates 100 um spaced micro-bunches with 5 ~ 6 % correlated energy spread. Two kinds of combined beamline simulation, CST-PS+Impact-Z and Elegant+Shower, including space charge and CSR effects, showed that a 900 um spaced, 300 um wide slits placed in the middle of chicane splits 20 pC – 1 nC bunches into ~ 100 um spaced micro-bunches. It is possible that a further optimization of mask design creates sub-100 fs micro-bunches, which is currently under development. [1] NIM A 375, 597 (1996) [2] PRL 101, 054801 (2008) [3] Y.-E Sun, P. R. G. Piot, FEMILAB-CONF-08-408-APC * ASTA: Advanced Superconducting Test Accelerator
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TUPME061	Ultra-High Gradient Beam-Driven Channeling Acceleration in Hollow Crystalline Media	plasma, electron, target, scattering	1512
	Y.-M. Shin, T. Xu Northern Illinois University, DeKalb, Illinois, USA G. Flanagan Muons, Inc, Illinois, USA E.R. Harms, J. Ruan, V.D. Shiltsev Fermilab, Batavia, Illinois, USA
	Since the recent discovery of the Higgs boson particle, there is an increasing demand in Energy Frontier to develop new technology for a TeV/m range of acceleration gradient. The density of charge carriers, ~ 10²⁴ – 10²⁹ m^-3, of crystals is significantly higher than that of a plasma gas, and correspondingly in principle wakefield gradients of up to 0.1 - 10 TV/m are possible. Our simulations (VORPAL and CST-PIC) with Fermilab-ASTA* beam parameters showed that micro-bunched beam gains energy up to ~ 70 MeV along the 100 um long channel under the resonant coupling condition of the plasma wavelength, ~ 10 um. Also, with lowering a charge, electron bunches channeling through a high-density plasma medium have higher energy gain in a hollow channel than in a uniformly filled cylinder, which might be attribute to lower scattering ratios of the tunnel structure. The numerical analysis implied that synthetic crystalline plasma media (e.g. carbon nanotubes) have potential to mitigate constraint of bunch charges required for beam-driven acceleration in high density plasma media. The channeling acceleration** will be tested at the ASTA facility, once fully commissioned. * ASTA: Advanced Superconducting Test Accelerator ** [1] T. Tajima and M. Cavenago, PRL 59, 13(1987) [2] P. Chen and R. Noble, SLAC-PUB-7402(1998) [3] V.Shiltsev, Physics Uspekhi 55, 965(2012)
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TUPME064	Laser-driven Acceleration with External Injection at SINBAD	plasma, laser, injection, simulation	1515
	J. Grebenyuk, R.W. Aßmann, U. Dorda, B. Marchetti DESY, Hamburg, Germany
	One of the important milestones to make plasma acceleration a realistic technology for user-applications is demonstration of bunch acceleration inside a plasma wake with minimal degradation of its quality. This can be achieved by external injection of beams into a plasma accelerator. SINBAD is a proposed dedicated accelerator research and development facility at DESY where amongst other topics laser-driven wakefield acceleration with external injection of ultra-short bunches will be exploited. To minimise energy-spread growth the bunch should occupy a small fraction of the plasma wavelength. In addition it has to be longitudinally synchronised with the laser driver to high accuracy. To avoid emittance growth the beam Twiss parameters have to be matched to the intrinsic beta-function of the plasma. To facilitate matching and synchronisation, acceleration at low plasma densities can be advantageous. We present a preparatory feasibility study for future plasma experiments at SINBAD using simulations with the particle-in-cell code OSIRIS. Field-gradient scaling laws are presented together with parameter scans of externally injected bunch, such as its injection phase, charge and length.
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TUPRI009	Study of Resonance Crossing in Non-scaling FFAGs using the S-POD Linear Paul Trap	resonance, ion, dipole, experiment	1571
	D.J. Kelliher, S. Machida, C.R. Prior, S.L. Sheehy STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom K. Fukushima, K. Ito, K. Moriya, H. Okamoto, T. Okano HU/AdSM, Higashi-Hiroshima, Japan
	Experiments on EMMA have shown that with rapid acceleration (~10 turns) a linear non-scaling FFAG can accelerate through several integer tunes without detrimental effects on the beam [1]. Proton and ion applications such as hadron therapy will necessarily have a slower acceleration rate, so their feasibility depends on how harmful resonance crossing is in this regime. A simple and useful tool to answer such fundamental questions is the S-POD linear Paul trap at Hiroshima University, which can be set up to simulate the dynamics of a beam in an FFAG. We report here results of experiments to explore different resonance crossing speeds, quantify beam loss and study nonlinear effects. We also discuss the implications of these experimental results in terms of limits on acceptable acceleration rates and alignment errors. [1] S.Machida et al, Nature Physics, N8, 243-257 (2012)
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TUPRI031	A Precise Beam Dynamics Model of the PSI Injector 2 to Estimate the Intensity Limit	space-charge, cyclotron, simulation, extraction	1630
	A.M. Kolano, R.J. Barlow University of Huddersfield, Huddersfield, United Kingdom A. Adelmann, C. Baumgarten PSI, Villigen PSI, Switzerland
	We describe a precise beam dynamics model of the production set up of the Injector 2 Cyclotron at the Paul Scherrer Institut (PSI). Injector 2 is a 72 MeV separate-sector cyclotron producing a high intensity proton beam up to 2.7 mA CW, which is then injected into the 590 MeV Ring Cyclotron. The model includes space charge and is calculated for optimised matched initial conditions. It has been verified with measurements. Based on this model we estimate the limits to the intensity obtainable from Injector 2. The precise beam dynamics model is based on the OPAL (Object Oriented Parallel Accelerator Library) simulation code, a tool for charged-particle optics calculations in large accelerator structures and beam lines including 3D space charge.
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TUPRI051	Comparison between Measurements and Orbit Code Simulations for Beam Instabilities due to Kicker Impedance in the 3-GeV RCS of J-PARC	simulation, impedance, injection, kicker	1683
	P.K. Saha, H. Harada, N. Hayashi, H. Hotchi, Y. Shobuda, F. Tamura, M. Yamamoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	The transverse impedance of the extraction kicker magnets is the most dominant beam instability source in the 3-GeV Rapid Cycling Synchrotron of J-PARC. The instability occurs when chromaticity is fully corrected during acceleration but on the other hand no instabilities are observed for a full chromatic correction only at the injection energy even for a beam power up to 500 kW. However, the situation may change for a beam power of 1 MW and also for the upgraded injection beam energy from the present 181 MeV to the 400 MeV, as space charge effect in the non-relativistic region is believed to suppress the growth rate of beam instability. In order to study the kicker impedance in detail, recently we have introduced measured time dependent impedance source in the ORBIT simulation code in a realistic manner. The ORBIT code itself has also been well upgraded and given realistic features for application to synchrotrons. We have also carried out a systematic experimental study for a maximum beam power of 500 kW. In this paper, a detail comparison between measurements and corresponding simulations including 1 MW simulation results are presented.
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WEXB01	Breaking the 70 MeV Proton Energy Threshold in Laser Proton Acceleration and Guiding Beams to Applications	laser, target, proton, ion	1886
	M. Roth, S. Bedacht, S. Busold, O. Deppert, G. Schaumann, A. Tebartz, F. Wagner TU Darmstadt, Darmstadt, Germany V. Bagnoud, A. Blazevic, D. Schumacher GSI, Darmstadt, Germany C. Brabetz IAP, Frankfurt am Main, Germany T.E. Cowan HZDR, Dresden, Germany K. Falk, A. Favalli, J.C. Fernandez, C. Gautier, C.E. Hamilton, R.P. Johnson, K. Schoenberg, T. Shimada, G.A. Wurden LANL, Los Alamos, New Mexico, USA M. Geißel, M. Schollmeier Sandia National Laboratories, Albuquerque, New Mexico, USA D. Jung Queen's University of Belfast, Belfast, Northern Ireland, United Kingdom F. Kroll Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiation Physics, Dresden, Germany
	This talk covers recent developments in laser plasma ion acceleration describing the technological challenges in breaking of energy threshold of 70 MeV. The presentation also highlights the recent experimental achievements towards laser ion acceleration and transport in the LIGHT collaboration.
	Slides WEXB01 [15.155 MB]
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WEOAB02	Wide-band Induction Acceleration in the KEK Digital Accelerator	induction, ion, synchrotron, experiment	1893
	T. Yoshimoto, X. Liu, K. Takayama TIT, Yokohama, Japan T. Adachi, K. Takayama Sokendai, Ibaraki, Japan T. Adachi, T. Arai, E. Kadokura, T. Kawakubo, X. Liu, K. Okamura, S. Takano, K. Takayama, T. Yoshimoto KEK, Ibaraki, Japan H. Asao, Y. Okada NETS, Fuchu-shi, Japan M. Hirose, H. Kobayashi Tokyo City University, Tokyo, Japan
	Induction synchrotron can accelerate any ion species directly to higher energy without a large pre-accelerator, due to its intrinsic nature that there is no frequency band-width limitation below 1 MHz. KEK digital accelerator (DA) is a small scale prototype of fast cycling induction synchrotron. Recently it has been confirmed that heavy ion beams of mass to charge ratio A/Q = 4 are stably accelerated from 200 keV to a few tens of MeV in this accelerator ring, where the revolution frequency changes from82 kHz to 1 MHz. Acceleration and beam confinement are separately realized by pulse voltages generated in induction cells (1 to 1 pulse transformers) driven by the switching power supply (SPS). Everything is simply maneuvered by controlling of gate signals of solid-state switching elements employed in the SPS. For this purpose, the fully programmed acceleration control system based on the FPGA has been developed. In this paper, the wide-band induction acceleration is presented with experimental results. Further possibilities of beam handling in the induction synchrotron, such as super bunch and novel beam handling techniques, are discussed. K.Takayama et al., to be submitted to Phys. Rev. Lett. (2013). ** T.Iwashita et al., Phys. Rev. ST-AB 14, 071301(2011).
	Slides WEOAB02 [8.935 MB]
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WEOAB03	Linear Electron Acceleration in THz Waveguides	electron, linac, laser, accelerating-gradient	1896
	E.A. Nanni, W.S. Graves, K.-H. Hong, W.R. Huang, F.X. Kärtner, KR. Ravi, L.J. Wong MIT, Cambridge, Massachusetts, USA A. Fallahi, F.X. Kärtner CFEL, Hamburg, Germany R.J.D. Miller DESY, Hamburg, Germany G. Moriena University of Toronto, Toronto, Ontario, Canada
	Funding: Supported by DARPA N66001-11-1-4192, CFEL DESY, DOE DEFG02-10ER46745, DOE DE-FG02-08ER41532, ERC Synergy Grant 609920 and NSF DMR-1042342. We report the first experimental demonstration of linear electron acceleration using an optically generated single cycle THz pulse centered at 0.45 THz. 7 keV of acceleration is achieved using 10 microJ THz pulses in a 3 mm interaction length. The THz pulse is produced via optical rectification of a 1.2 mJ, 1 micron laser pulse with a 1 kHz repetition rate. The THz pulse is coupled into a dielectric-loaded circular waveguide with 10 MeV/m on-axis accelerating gradient. A 25 fC input electron bunch is produced with a 60 keV DC photo-emitting cathode. The achievable accelerating gradient in the THz structures being investigated will scale rapidly by increasing the IR pulse energy (100 mJ - 1 J) and correspondingly the THz pulse energy. Additionally, with recent advances in the generation of THz pulses via optical rectification, in particular improvements to efficiency and generation of multi-cycle pulses, GeV/m accelerating gradients could be achieved. An ultra-compact high-gradient THz accelerator would be of interest for a wide variety of applications.
	Slides WEOAB03 [7.185 MB]
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WEPRO061	Optimization of the SIS18 Injector Operation for FAIR	operation, experiment, controls, space-charge	2088
	D. Ondreka, H. Liebermann, B.R. Schlei GSI, Darmstadt, Germany
	In the FAIR accelerator complex, the existing synchrotron SIS18 will serve as an injector, supplying intense beams of heavy ions and protons for further acceleration in the synchrotron SIS100. In order to satisfy the intensity requirements for FAIR, SIS18 has to be operated routinely at the space charge limit. Particularly demanding requirements arise from the operation with medium charge state heavy ions due to the dynamic vacuum created by ions lost through charge exchange reactions. It is therefore crucial to avoid losses in SIS18 as much as possible while confining unavoidable losses onto low desorption surfaces. In this contribution we report on the ongoing activities related to minimizing the losses by means of a better quantitative understanding and control of the beam. This includes the development of more accurate theoretical models, benchmarked with machine experiments, as well as the practical integration of the models into the control system, using beam instrumentation data in the calculation of set values whenever possible.
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WEPRO062	Reacceleration of Ion Beams for Particle Therapy	synchrotron, ion, extraction, operation	2091
	C. Schömers, R. Cee, E. Feldmeier, M. Galonska, Th. Haberer, A. Peters, S. Scheloske HIT, Heidelberg, Germany
	At the Heidelberg Ion-Beam Therapy Centre (HIT) cancer patients are treated using the raster-scanning method. A synchrotron provides pencil beams in therapy quality for 255 energy steps per ion type allowing to vary the penetration depth and thus to irradiate tumors slice-by-slice. So far, changing the beam energy necessitates a new synchrotron cycle, including all phases without beam extraction. As the no. of ions that can be accelerated in the synchrotron usually exceeds the required no. of ions for one energy slice, treatment time could be significantly reduced by reaccelerating or decelerating the remaining ions to the next energy level. By alternating acceleration and extraction phases several slices could be irradiated with only short interruptions. Therefore the reacceleration of a transversally blown up beam – due to RF-knockout extraction – must be investigated, beam losses have to be minimized. To estimate the benefit of this operation mode, treatment time has been simulated and compared to the time achieved in the past. A reduction of up to 65% is possible and more patients can be treated! Simulations and first tests of a reaccelerated and extracted beam are presented.
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WEPRI030	Multipactor Simulation on Superconducting Spoke Cavity for Laser Compton Scattered Photon Sources	multipactoring, cavity, simulation, electron	2543
	Y. Iwashita, H. Fujisawa, H. Tongu Kyoto ICR, Uji, Kyoto, Japan R. Hajima, R. Nagai, M. Sawamura JAEA, Ibaraki-ken, Japan T. Kubo KEK, Ibaraki, Japan
	Funding: This work is supported by Photon and Quantum Basic Research Coordinated Development Program. Superconducting spoke cavity for laser Compton scattered (LCS) photon sources is under development. The operating frequency is 325-MHz to accelerate electron beam for the LCS sources, where the size of the spoke cavity is less than a elliptical cavities with the same frequency. Because of the complicated shape of the cavity, it may be suffered from a strong multipactor effect. The recent results on the multipactor analysis will be presented.
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WEPRI090	Cyclotron C235-V3 for Dimitrovgrad Hospital Center of the Proton Therapy	cyclotron, proton, extraction, focusing	2703
	S.A. Kostromin, S. Gurskiy, G.A. Karamysheva, M.Y. Kazarinov, S.A. Korovkin, S.P. Mokrenko, N.A. Morozov, A.G. Olshevsky, V.M. Romanov, E. Samsonov, N.G. Shakun, G. Shirkov, S.G. Shirkov, E. Syresin JINR, Dubna, Moscow Region, Russia P. Cahay, Y. Jongen, Y. Paradis IBA, Louvain-la-Neuve, Belgium
	JINR-IBA C235-V3 isochronous cyclotron for 1st Russian hospital center of the proton therapy has been assembled and tested. Shimming of the magnetic field, optimization of the acceleration modes and testing with the extracted proton beam were done in frame of this work. The paper presents experimental results of the beam dynamics in the accelerator. Proton transmission from radius 30cm to 103cm is 72% without beam cutting diaphragms. The extraction efficiency is 62%. This cyclotron is a substantially modified version C235-V3 of the IBA C235 serial cyclotron. C235-V3 has the improved extraction system which was constructed and tested. This system allows raise the extraction efficiency up to 77% from 50% in comparison with serial C235. Special mapping system (for Br-component) of the magnetic field was developed and constructed by JINR for the shimming of the Br-field in the middle plane of the cyclotron. Total efficiency of the machine is 45%. Further improvement of the parameters expected after final tuning of the cyclotron in Dimitrovgrad.
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THPRO070	Beam Dynamics Simulations in Cyclotron C230 Considering Imperfections of Magnetic Field Radial Component	cyclotron, proton, simulation, focusing	3038
	E. Samsonov, S.A. Kostromin, N.A. Morozov, E. Syresin JINR, Dubna, Moscow Region, Russia
	Simulations concern to a beam axial motion in the IBA cyclotron C230 that is a base facility in several medical centers worldwide. Because of small axial focusing of the beam in a center of the cyclotron the radial component of magnetic field imperfections leads to additional proton losses. Measured maps of the axial and radial components of magnetic field were used in the simulations. It was found that the radial component with value 5-10 G in the center and approximately 2 G in the main region of acceleration leads to decrease of the resulting beam intensity by about two times and to increase the beam axial width by 25% as well. Simulations define the requirements to the experimental radial component shaping for the next cyclotrons of this series. Providing these requirements will ensure an absence of the additional proton losses due to the axial motion perturbations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO070
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THPRO073	Longitudinal Acceptance Evaluation from Hamiltonian	cavity, linac, simulation, lattice	3047
	E. Laface ESS, Lund, Sweden
	An RF cavity is designed around a reference particle; if the energy or the phase of a real particle are too far from the reference, the particle is lost. The widest area of energy-phase that allows a particle to be transported by the cavity is called acceptance of the cavity. In simulations the acceptance is evaluated tracking several particles with different energies and phases and marking when a particle is transmitted or lost. This process can be time consuming because of the large amount of tracked particles requested to characterise the cavity acceptance. In this paper we propose an alternative method to evaluate the acceptance studying directly the Hamiltonian associated to the cavity.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO073
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THPRO082	Observation of Coherent Instability in the CERN PS Booster	quadrupole, closed-orbit, booster, simulation	3076
	M. McAteer, C. Carli, V. Forte, G. Rumolo, R. Tomás CERN, Geneva, Switzerland
	Funding: This project has been supported by a Marie Curie Early Initial Training Network Fellowship of the European Community's Seventh Framework Programme, contract number (PITN-GA-2011-289485-OPAC). At high intensities and at a certain working point an instability develops in the CERN PS Booster, and large coherent transverse oscillations and beam loss occur. The coherent oscillations and beam loss can be effectively controlled with the transverse damper system, but the origin of the instability is not well-understood. Recent measurements with the PSB's new trajectory measurement system have provided some insight into the nature of this instability, and these observations are presented here.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO082
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THPRO084	Beam Dynamics Observations of Slow Integer Tune Crossing in EMMA	simulation, lattice, synchrotron, injection	3082
	J.M. Garland, H.L. Owen UMAN, Manchester, United Kingdom D.J. Kelliher, S. Machida STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom B.D. Muratori STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	When the betatron tune is an integer in a cyclical accelerator, dipole-field errors can drive the coherent addition of betatron amplitude to the bunch eventually causing particle loss. Transverse integer tune crossing in a linear non-scaling FFAG is inevitable due to finite chromaticity. In EMMA (Electron Machine with Many Applications), as many as 6 integers may be crossed is as little as 6 turns at maximum acceleration over the 10 – 20 MeV energy range. This fast integer tune crossing, of the order 1 integer per turn, was shown to have little effect on the coherent amplitude growth and charge loss rate. Slower acceleration inside an RF bucket in EMMA allowed the experimental exploration of slower integer tune crossing speeds, of the order of a factor ten slower. The effect on the coherent oscillation amplitude was observed and the charge loss at integer tune crossings indicated resonant effects on the bunch. Simulations in Zgoubi allowed a more detailed analysis and the mechanism of slower resonance crossing in a non-scaling FFAG is discussed, including the importance of coupled longitudinal-transverse decoherence on the effective emittance.
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THPRO088	Optimization of the pp AGS Zgoubi Model in the Low Energy Range	resonance, simulation, emittance, betatron	3089
	Y. Dutheil, H. Huang, F. Méot, N. Tsoupas BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. At low energy the AGS lattice is strongly deformed by the two strong helical snakes, required to preserve the polarization. In addition to the complex, highly non-linear field featured by the two snakes, multiple non-linear coupling resonance lines are crossed by the beam in this region. Hence, the use of realistic models for the Siberian snakes is critical for the simulation of the early part of the AGS acceleration cycle. The AGS Zgoubi model uses direct tracking through OPERA field maps of the two snakes. While many processes may be obnoxious to both beam and spin dynamics in this region, it is critical to use a realistic model of the AGS at low energy. This paper presents the current model used and some of the challenges recently faced. We will also compare experimental beam dynamics results to those predicted by the Zgoubi model.
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THPRO089	New Tune Jumps Scheme in the Low Energy Part of the AGS Cycle	polarization, resonance, simulation, hardware	3092
	Y. Dutheil, L. Ahrens, J.W. Glenn, H. Huang, F. Méot, V. Schoefer BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. During the early part of the acceleration of polarized protons, due to strong optical deformations of the lattice, the tune cannot be placed in the spin gap and the first two vertical intrinsic resonances are crossed. Recent multiparticle trackings using the Zgoubi code show that the spin resonances around Gg=5 could cause as much as 5% loss of polarization. The slow acceleration rate, the two vertical and two horizontal intrinsic spin resonances can contribute to the depolarization in the region. While in the current scheme only the two horizontal intrinsic resonances are jumped, it was proposed to use the tune jumps system to also accelerate the crossing of the two weak vertical intrinsic resonances and improve the polarization transmission through this region. We show the design of this new tune jumps scheme and the expected polarization gains expected from multiparticles Zgoubi simulations. We also compare experimental measurements of the polarization transmission to the Zgoubi simulations.
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THPRO090	Energy Calibration and Tune Jumps Efficiency in the pp AGS	polarization, timing, resonance, extraction	3095
	Y. Dutheil, L. Ahrens, H. Huang, F. Méot, A. Poblaguev, V. Schoefer, K. Yip BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The AGS tune jump system consists of two fast quadrupoles used to accelerate the crossing of 82 horizontal intrinsic spin resonances. The fast tune jump of ΔQh=+0.04 within 100 μs imposes perfect localization of each of the 82 resonant conditions. Imperfect timing of the tune jumps results in lower efficiency of the system and lower transmission of the polarization through the AGS acceleration cycle. Investigations during the end of the pp AGS Run13 revealed weaknesses in the energy measurement at high energy, causing less than optimal timing of the tune jumps. A new method based on continuous polarization measurement to determine the energy during the acceleration cycle has been developed. Strong operational constraints were taken into account to provide a convenient system of energy measurement. This is also used to calibrate the usual determination of the energy based on revolution frequency of the beam or measured dipole magnetic field. This paper shows the tools developed and the results of the first tests during the AGS Run 14. Simulations of the expected tune jumps efficiency using the AGS Zgoubi model are also presented and compared to experimental results.
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THPRO102	Generation of RF Frequency and Phase References on the FAIR Site	controls, electronics, hardware, cavity	3131
	B. Zipfel, H. Klingbeil, U. Laier, K.-P. Ningel, S. Schäfer, C. Thielmann GSI, Darmstadt, Germany U. Hartel, H. Klingbeil TEMF, TU Darmstadt, Darmstadt, Germany D.E.M. Lens TU Darmstadt, RTR, Darmstadt, Germany
	Based on the Bunch Phase Timing System (BuTiS)* local analog radio frequency reference signals (RF references) like the particle revolution frequency and their multiple harmonics will be generated. These references are used to control the phase of the accelerator cavities to altering harmonics of the bunch revolution frequency. Delay or phase shifts from the FAIR-Center to references at the BuTiS endpoints are already compensated by the BuTiS receivers. Phase shifts from the RF reference generators to LLRF electronics can be compensated by controlling the output phases of the DDS modules of the RF references. However phase shift delays of multiple harmonics at the same interconnecting electrical path are not identical at the same time. Configurable electronics** manage phase calibration of the RF references to their endpoints. Calibration may depend on frequency and harmonic of the RF reference, aging as well as on thermal effects. The electrical length and impedance of interconnecting cables for phase control loops can be compensated. This is an important feature, in particular if control loops are switched between different harmonic frequencies. B. Zipfel, P. Moritz: Proc. IPAC 2011, San Sebastian *S. Schäfer, et al.: Proc. IPAC 2013, Shanghai
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THPME027	Development of the injector II RFQ for China ADS project	rfq, cavity, linac, proton	3280
	Z.L. Zhang, Y.H. Guo, Y. He, H. Jia, C.X. Li, Y. Liu, L. Lu, G. Pan, A. Shi, L.B. Shi, L.P. Sun, W.B. Wang, X.W. Wang, J.X. Wu, Q. Wu, X.B. Xu, B. Zhang, J.H. Zhang, H.W. Zhao, T.M. Zhu IMP, Lanzhou, People's Republic of China M.D. Hoff, A.R. Lambert, D. Li, J.W. Staples, S.P. Virostek LBNL, Berkeley, California, USA C. Zhang GSI, Darmstadt, Germany
	As one of the main components of the injector II of China ADS LINAC project, an RFQ working at 162.5MHz is used to accelerate proton beams of 15mA from 30 keV to 2.1 MeV. The four vane RFQ has been designed in collaboration with Lawrence Berkeley National Laboratory and built at the workshop of the Institute of Modern Physics, Chinese Academy of Sciences (IMP, CAS). Low power test of the cavity have been completed, and it shows the field flatness is within ±1% and the unloaded Q is 12600. RF conditioning has been completed, results of preliminary beam test show the output beam energy is 2.16 MeV with energy spread of 3.5% and the transmission efficiency is 97.9%. Continuous wave (CW) beam of 2.3 mA has been accelerated for more than one hour.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME027
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THPME029	Upgrade of Heavy Ion Injector for ITEP-TWAC Facility	ion, simulation, heavy-ion, focusing	3283
	V. Andreev, N.N. Alexeev, A.I. Balabin, M.M. Kats ITEP, Moscow, Russia A.A. Metreveli MEPhI, Moscow, Russia
	A new scheme of heavy ion injector I-3 designed for improvement of accelerated beam parameters has been proposed for ITEP-TWAC Facility. It is based on the usage of two quarter-wave double gap resonators operated on 5 MHz with accelerating voltage of 3 MV per gap. Existing 2.5 MHz double gap resonator will be retuned for operational frequency of 5 MHz and new additional one will be built. The new injector optimized for acceleration of heavy ions with A/Z in the range of 3-10 will allow accelerating any ions from C to U with beam current up to10 mA. Results of both electrodynamics and beam dynamics simulations of the accelerating structures are presented.
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THPME032	Beam Transfer Studies for LINCE Experimental Areas	optics, beam-transport, quadrupole, linac	3292
	L. Acosta, C. Bonțoiu, I. Martel, A.R. Pinto Gómez, A.C.C. Villari University of Huelva, Huelva, Spain J. Lucas Elytt Energy, Madrid, Spain A.C.C. Villari FRIB, East Lansing, Michigan, USA
	Funding: Work partially supported by the Spanish Government (MINECO-CDTI) under program FEDER INTERCONNECTA. Beam transport from the exit of the LINCE linac to experimental areas has been optimized for a few ion species using transfer matrix calculations performed in MADX. An alpha spectrometer based on a double-bending achromat lattice has been used as dispersion suppressor and particle tracking studies have been carried out in GPT along it and the three beamlines. Realistic quadrupole and dipole magnet design achieved in Comsol enabled accurate particle tracking studies and evaluation of the beam parameters delivered at the target.
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THPME067	Air Stripper for Intense Heavy Ion Beams	target, ion, cyclotron, heavy-ion	3388
	H. Imao RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama, Japan M. Fujimaki, N. Fukunishi, H. Hasebe, O. Kamigaito, M. Kase, H. Kuboki, H. Okuno, Y. Yano RIKEN Nishina Center, Wako, Japan
	Intensity upgrade of very heavy ions such as uranium or xenon beams is one of the main concerns at the RIKEN Radioactive Isotope Beam Factory (RIBF). The lifetime problem of carbon-foil strippers due to the high energy loss of beams was a principal bottleneck for the intensity upgrade. We have already developed and successfully operated a re-circulating He-gas stripper for 10-MeV/u uranium beams as an alternative to carbon foils. Recently, the 2nd gas stripper with air dedicated for 50-MeV/u ¹²⁴Xe beams was developed. The differential pumping techniques similar to that used in the He gas stripper was applied. We confined a very thick gas target, up to 20~mg/cm² of air, in a 0.5-m target chamber. One good feature of using air is that it can be inexhaustible for our use. The stripper was stably operated in user runs performed in June 2013. The service rate reached 91\%. The maximum beam intensity reached 38~pnA and the average intensity provided to users becomes approximately four times higher than it was in 2012. The down-time free gas strippers greatly contributed to these improvements. We also discuss the applicability of the air stripper to 50-MeV/u ²³⁸U beams.
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THPRI013	A Beam Driven Plasma-wakefield Linear Collider from Higgs Factory to Multi-TeV	plasma, electron, positron, linear-collider	3791
	J.-P. Delahaye, E. Adli, S.J. Gessner, M.J. Hogan, T.O. Raubenheimer SLAC, Menlo Park, California, USA W. An, C. Joshi, W.B. Mori UCLA, Los Angeles, California, USA
	An updated design of a beam-driven Plasma Wake-Field Acceleration Linear Collider (PWFA-LC) covering a wide range of beam collision energy from Higgs factory to multi-TeV is presented. The large effective accelerating field on the order of 1 GV/m and high wall-plug to beam power transfer efficiency of the beam driven plasma technology in a continuous operation mode allows to extend linear colliders to unprecedented beam collision energies up to 10 TeV with reasonable facility extension and power consumption. An attractive scheme of an ILC energy upgrade using the PWFA technology in a pulsed mode is discussed. The major critical issues and the R&D to address their feasibility in dedicated test facilities like FACET and FACET2 are outlined, especially the beam quality preservation during acceleration and the positron acceleration. Finally, a tentative scenario of a series of staged facilities with increasing complexity starting with short term application at low energy is developed.
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THPRI035	Design and Simulation of Side Coupled Six MeV Linac for X-Ray Cargo Inspection	cavity, coupling, simulation, electron	3844
	S. Ahmadiannamin, F. AbbasiDavani, R. Ghaderi, F. Ghasemi sbu, Tehran, Iran M. Lamehi Rashti IPM, Tehran, Iran S. Zarei Nuclear Science and Technology Research, InstituteRadiation Application School, Tehran, Iran
	Using in X-ray cargo inspection is one of most applications of linear accelerators. This paper represents design and simulation of Side Coupled Six MeV cavity. The electromagnetic simulation of structure was carried out in the SUPERFISH and CST Microwave studio. 2.3 MW input power is considered according to MG5193 magnetron. The coupling coefficient is calculated equal to 3% for stabilization of accelerator operation against environmental and mechanical errors effects.
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THPRI046	Air-cooled Magnetic Alloy Cavity for J-PARC Doubled Rep.-rate Scenario	cavity, impedance, injection, ion	3869
	C. Ohmori, K. Hara, K. Hasegawa, K. Takata, M. Toda, M. Yoshii KEK, Ibaraki, Japan M. Nomura, A. Schnase, T. Shimada, F. Tamura, M. Yamamoto JAEA/J-PARC, Tokai-mura, Japan
	The upgrade project of the J-PARC MR (Main Ring) is in progress to deliver the beam power of 750 kW based on doubled repetition-rate scenario. The present RF section will be occupied by 9 sets of new magnetic alloy, FT3L, cavity using the direct water cooling scheme. The direct water cooling requires dedicated high-quality cooling water. These cavities will be used for the fundamental RF for acceleration. The second harmonic RF is necessary to increase the bunch length. This allows to enlarge the beam current, and to relax the space charge effects during the injection. Thanks to the high impedance FT3L, the power loss in the second harmonic RF system becomes moderate. The air cooled cavity is designed to fit in any space in the MR where the dedicated water is not available. This paper reports the design of the second RF system, technical issues to produce the magnetic alloy cores to fit the air cooling, and construction of the system.
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THPRI047	Large-aperture Travelling-wave Accelerator Structure for Positron Capture of SuperKEKB Injector Linac	positron, operation, linac, solenoid	3872
	S. Matsumoto, T. Higo, K. Kakihara, T. Kamitani, M. Tanaka KEK, Ibaraki, Japan
	Comparing to the previous KEKB, the four-times higher charge of 4 nC per bunch is required for the injector linac of SuperKEKB. Not only a flux concentrator will be introduced but also the physical aperture of the downstream six 2m-long accelerator structures was increased as large as 30mm in diameter. We call these structures as LAS, “Large Aperture S-band” structure. The resultant higher RF group velocity of about 3% makes the acceleration gradient lower. In the nominal acceleration system, a 40MW klystron with SLED feeds four 2m-long accelerator structures producing 20MV/m acceleration field. The acceleration gradient higher than 14 MV/m is required for the very first two LAS structures to suppress the satellite bunches. This gradient is obtained by feeding only two LAS structures. Initially, ten LAS structures were installed and the RF processing has partly started. In the present paper, we firstly describe the acceleration system design and then present the processing characteristics through the RF processing without beam and with beam.
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THPRI052	Design, Fabrication and Tests of the Second Prototype of the Double-Length CLIC PETS	vacuum, alignment, collider, RF-structure	3887
	L. Sánchez, J. Calero, D. Gavela, J.L. Gutiérrez, F. Toral CIEMAT, Madrid, Spain D. Gudkov, G. Riddone CERN, Geneva, Switzerland
	Funding: This work has been partially funded by the Spanish Ministry of Economy and Competitiveness under project FPA2010-21456-C02-02 The future collider CLIC is based on a two-beam acceleration scheme, where the drive beam provides to the main beam the RF power through the Power Extraction and Transfer Structures (PETS). The technical feasibility of some components is currently being proved at the CLIC Experimental Area (CLEX). Two double- length CLIC PETS will be installed in CLEX to validate their performance with beam. The first prototype was produced and validated in 2012. This paper is focused on the engineering design, fabrication and validation of the second prototype. Taking into account the results of the first prototype, some modifications have been included in the design to ease fabrication and assembly. The fabrication techniques are very similar to the ones used for the first prototype. Mechanical measurements on single parts and different assembly stages will be reported. The industrialization feasibility will be also analyzed. Finally, several tests such as vacuum tightness and RF measurements with low power have been realized to validate the device. These results are compared with the first prototype ones.
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THPRI080	The New Design for Capture Cavity of CEBAF	cavity, coupling, electron, simulation	3955
	S. Wang, J. Guo, R.A. Rimmer, H. Wang JLab, Newport News, Virginia, USA
	In CEBAF, the electron beam from the injector must be sufficiently relativistic to match a 1 GeV recirculated beam in the first linac. The electron beam is produced with a ~130 keV electron gun, then accelerated by a room temperature, graded-beta standing wave linac, capture section, from 130 keV to 510 keV before enters two 5-cell superconducting RF cavities for further acceleration. Present capture cavity is a 5-cell side-coupled cavity. We designed a new slot-coupled cavity which has lower power consumption and simpler structure.
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FRYBA01	Long-term Accelerator R&D as an Independent Research Field	laser, electron, plasma, SRF	4073
	R. Brinkmann DESY, Hamburg, Germany
	High energy physics projects have been important drivers of accelerator R&D for several decades. The resulting accelerator technology was used to construct frontier accelerators for HEP but was also very successfully applied in accelerators for other science fields, in particular photon science, nuclear physics, medical applications, … Fewer HEP projects and at the same time a growing number of projects in other areas require a modified approach to accelerator R&D. Efforts and progress to perform accelerator R&D as an independent research program with its own, independent funding are described for the example of the Helmholtz ARD program in Germany. Links to efforts in other countries are discussed and an outlook to future accelerator research is given.
	Slides FRYBA01 [3.581 MB]
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Paper

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MOPRO003

Towards Stable Acceleration in Linacs

klystron, bunching, electron, linac

65

A. Dubrovskiy
Private Address, Geneve, Switzerland

Ultra-stable and -reproducible high-energy particle beams with short bunches are needed in novel linear accelerators and, in particular, in the Compact Linear Collider CLIC. A passive beam phase stabilization system based on a bunch compression with a negative transfer matrix element R56 and acceleration at a positive off-crest phase is proposed. The motivation and expected advantages of the proposed scheme are outlined.

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MOPRO016

NANOPERM® Broad Band Magnetic Alloy Cores for Synchrotron RF Systems

synchrotron, target, damping, background

95

T. Trupp
MAGNETEC GmbH, Langenselbold, Germany

Recent developments in synchrotron acceleration systems show a demand for broadband MA (Magnetic Alloy) magnetic core loaded cavities with a high field gradient. For many facilities e.g. GSI, CoSY, J-Parc limited installation lengths requires high gradients in the region of 40kV/m. Both requirements rule out ferrite materials due to the lower maximum excitation levels and high Q-value. This request can solely be met by Finemet type cores like NANOPERM® produced by MAGNETEC. In this paper, the statistics of 22 huge cores made of NANOPERM® and measured high frequency properties are shown under free-space (FS) condition and compared with the theoretical expectation.

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MOPRO115

A Low Energy Electron-Scrapersystem for the S-DALINAC Injector

electron, linac, controls, target

366

L.E. Jürgensen, T. Bahlo, C. Burandt, F. Hug, T. Kürzeder, N. Pietralla, T. Schösser, C. Ungethüm
TU Darmstadt, Darmstadt, Germany

Funding: Work supported by DFG through SFB 634
The S-DALINAC is the superconducting linear accelerator of the Institut für Kernphysik at Technische Universität Darmstadt. It delivers an electron beam with energies up to 130 MeV. In order to improve the energy spread and the energy stability of the beam for further acceleration a new scrapersystem has been developed and installed between the 10 MeV injector and the main linac. The system was designed to ensure an energy spread of dE < 10^-03. After installation several tests have taken place, the results will be presented in this work.

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MOPME035

Current Status of the GPU-Accelerated ELEGANT

GPU, operation, simulation, linac

454

I.V. Pogorelov, K.M. Amyx, J.R. King
Tech-X, Boulder, Colorado, USA
M. Borland, R. Soliday
ANL, Argonne, Ilinois, USA

Funding: Work supported by the DOE Office of Science, Office of Basic Energy Sciences grant No. DE-SC0004585, and in part by Tech-X Corporation.
Efficient implementation of general-purpose particle tracking on GPUs can result in significant performance benefits to large-scale tracking simulations. This presentation is an update on the current status of our work on accelerating Argonne National Lab’s particle accelerator simulation code ELEGANT using CUDA-enabled GPU. We summarize the performance of beamline elements ported to GPU, and discuss optimization techniques for some important collective effects kernels, in particular our methods of avoiding costly thread contention. We also present preliminary results of a scaling study of the GPU-accelerated version of the code.

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MOPME051

Turbo Generators for Powering the HV-solenoids at the HESR Electron Cooler

solenoid, electron, high-voltage, power-supply

492

A. Hofmann, K. Aulenbacher, M.W. Bruker, J. Dietrich, T. Weilbach
HIM, Mainz, Germany
M.I. Bryzgunov, A.P. Denisov, V.M. Panasyuk, V.V. Parkhomchuk, V.B. Reva
BINP SB RAS, Novosibirsk, Russia

New experiments at the planned 'High Energy Storage Ring' (HESR) require magnetised electron cooling. One of the challenges is the powering of the HV-solenoids, because they are located on HV-sections, which sit on an electrical potential inside a high voltage vessel. We discuss a Multi-MV system where the solenoids are powered by a series of cascade transformers which are in turn supplied by turbogenerators. The usage of SF6 as turbine fluid is desirable from the viewpoint of operational stability and may also lead to energy efficient operation of the turboexpanders since a Organic Rankine-cycle (so-called ORC-process) may be used instead of electrically driven compressors. The paper gives an overview of the turbo generator and ORC project: an introduction, a status report and a road map will be given.

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MOPME068

SiC-JFET Switching Power Supply toward for Induction Ring Accelerators

ion, extraction, induction, injection

523

K. Okamura, K. Takayama, M. Wake, T. Yoshimoto
KEK, Ibaraki, Japan
R. Sasaki, K. Takaki
Iwate university, Morioka, Iwate, Japan
K. Takayama, T. Yoshimoto
TIT, Yokohama, Japan
F. Tamura
Nagaoka University of Technology, Nagaoka, Niigata, Japan

Funding: Japan Science and Technology Agency Grant-In Aid for Scientific Research(s) (KAKENHI No. 24310077)
A new induction synchrotron system using an induction cell has been developed and constructed at KEK*. In that system, the switching power supply is one of the key devices that realize digital acceleration. The requirements of the switching power supply are high voltage (2 kV) and high repetition frequency (1 MHz). In the present system, we used series connected MOSFETs as the switching device. However, series connection gives large complexity and less reliability. Among various switching devices, a SiC-JFET should be a promising candidate because it has ultrafast switching speed and high voltage blocking capability. We have developed a new and original SiC-JFET switching device and a compact switching power supply employing this switching element**. Now it is integrated into the induction acceleration system for the KEK-DA. Furthermore we have started development of the next generation of SiC package, which has higher voltage capability (2.4 kV) and 2 in 1 module construction. At the conference, the first experimental demonstration of heavy ion acceleration utilizing the SiC-JFET and the design status of the new device package will be presented.
* T. Iwashita et al., Phys. Rev. ST-AB 14, 071302 (2011).
** K. Okamura et al., “A Compact Switching Power Supply Utilizing SiC-JFET for The Digital Accelerator ”, in Proc. of IPAC’12, pp 3677-3679.

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MOPRI072

Simulation Study of Heavy Ion Beam Injection and Acceleration in the HESR for Internal Target Experiments with Cooling

target, ion, experiment, cavity

768

H. Stockhorst, B. Lorentz, R. Maier, D. Prasuhn, R. Stassen
FZJ, Jülich, Germany
T. Katayama
Nihon University, Narashino, Chiba, Japan

Recently, the feature of ion beam injection, storage and acceleration assisted by a barrier bucket and cooling has been investigated in the High Energy Storage Ring HESR at the new facility FAIR which will be built at the GSI Darmstadt. A bare uranium beam is injected from the collector ring CR into the HESR at 740 MeV/u*. The simulation studies are now improved to include different injection schemes applying either the barrier cavity or the h = 1 cavity in the HESR. It is outlined how the new 2.5 MeV electron cooler at COSY Jülich or stochastic cooling can support the injection mechanism. The beam preparation for an internal target experiment with cooling is outlined. The acceleration of the ion beam is extended to 5 GeV/u under the mandatory condition of the available cavity voltages and the maximum magnetic field ramp rate in the HESR. The flexibility of the HESR ring lattice is utilized to avoid transition energy crossing during ramping up to 5 GeV/u and to adjust the rings’ frequency slip factor for optimal stochastic cooling. The cooling simulations include the beam-target interaction due to a hydrogen target.
* H. Stockhorst et al., MOPEA018, IPAC13

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MOPRI074

Conceptual Project Relativistic Electron Cooler for FAIR/HESR

electron, proton, high-voltage, cathode

774

V.V. Parkhomchuk, M.I. Bryzgunov, A.P. Denisov, V.M. Panasiuk, V.B. Reva
BINP SB RAS, Novosibirsk, Russia
K. Aulenbacher, J. Dietrich
HIM, Mainz, Germany
V. Kamerdzhiev
FZJ, Jülich, Germany

To develop a 4 MeV relativistic electron cooling system for the HESR storage ring, which is part of the future GSI facility FAIR, is proposed to further boost the luminosity even with strong heating effects of high-density internal targets. In addition the upgrade to 8 MeV of the relativistic electron cooler is essential for the future Electron Nucleon Collider (ENC@FAIR) project. The basic feature of the design are the power for magnet field coils at accelerating and decelerating column is generated by turbines (one option under investigation in this research group) operated on SF6 gas under pressure

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MOPRI076

Simulation of Dynamics in Ultra-compact Isochronous Medium Energy Racetrack FFAGs

cyclotron, focusing, dynamic-aperture, lattice

780

R. Appleby, J.M. Garland, H.L. Owen, S.C. Tygier
UMAN, Manchester, United Kingdom
K.M. Hock
Cockcroft Institute, Warrington, Cheshire, United Kingdom
C. Johnstone
PAC, Batavia, Illinois, USA

Funding: Research supported by STFC grant number ST/K002503/1 "Racetrack FFAGs for medical, PRISM and energy applications".
The FFAG (Fixed-Field Alternating-gradient) accelerator is a class of accelerators that comprises the best features of the cyclotron and the synchrotron, combining fixed magnetic fields with strong focusing gradients for optimal stable, low-loss operation. Here, a new type of medium-energy 1-GeV isochronous (CW) FFAG has been developed in a racetrack layout that supports two opposing synchrotron-like straights, permitting both high-gradient RF modules and efficient injection and extraction in a highly compact footprint. In this paper we present beam dynamic simulations for this compact racetrack FFAG, and compare the differences between an equivalent circular and a racetrack configuration. A comparison of the FFAG dynamics with the 800-MeV (Daeδalus) cyclotron is briefly presented.

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MOPRI080

Measurement of Beam Phase using Phase Probe at the NIRS-930 Cyclotron

pick-up, extraction, cyclotron, septum

794

S. Hojo, K. Katagiri, M. Nakao, A. Noda, K. Noda, A. Sugiura
NIRS, Chiba-shi, Japan
T. Honma, A.K. Komiyama, T. Okada, Y. Takahashi
AEC, Chiba, Japan

The NIRS-930 cyclotron of the National Institute of Radiological Sciences (NIRS) has been used for production of short-lived radio-pharmaceuticals for PET, research of physics, developments of particle detectors in space, and so on. The NIRS-930 has twelve trim coils for generation of the isochronous fields. Until recently, currents of the twelve trim coils had been adjusted only by monitoring the beam intensity. In order to exactly produce the isochronous fields, a phase probe has been installed in the NIRS-930. Recent results of beam tests using the phase probe will be presented in the present work.

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MOPRI093

Technical Design of Normal Conducting Re-buncher in the MEBT for Rare Isotope Science Project

cavity, rfq, ion, operation

830

H.J. Kim, W.K. Han, I.S. Hong, D. Jeon
IBS, Daejeon, Republic of Korea

Funding: This work was supported by the RISP of Institute for Basic Science funded by Ministry of Science, ICT and Future Planning and National Research Foundation of Korea.(2011-0032011)
The front-end system of RISP heavy-ion accelerator(RAON) consists of an electron cyclotron resonance ion source, a low energy beam transport line, a radio frequency quadrupole accelerator and a medium energy beam transport(MEBT) line. The MEBT system, which consists of quadrupole magnets, three normal-conducting re-bunchers and diagnostic devices, is installed between the RFQ accelerator and the superconducting linac(SCL). The three normal-conducting re-bunchers are used to minimize the growths of the longitudinal emittance and to manipulate the particle distribution on longitudinal phase space for beam transportation in SCL. Several combination of the number of cavities was examined, and the quarter wave resonator(QWR) type re-buncher was chosen for MEBT line in RAON. The QWR cavity has a frequency of 81.25 MHz, a maximum electric field of 2.53 MV/m on the cavity surface with an electric field of 1 MV/m on the beam axis, a geometrical beta factor of 0.032 and an effective length of 24 cm. In this presentation, I will present the results of baseline design for electro-magnetic field analysis and mechanical design for stress analysis, thermal stress analysis and cooling channel.

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MOPRI103

Longitudinal Bunch Shortening for the Laser Stripping Project

laser, cavity, focusing, linac

861

T.V. Gorlov, A.V. Aleksandrov, S.M. Cousineau, V.V. Danilov, Y. Liu, M.A. Plum
ORNL, Oak Ridge, Tennessee, USA

Funding: This work is funded by the U.S. DOE under grant number DE-FG02-13ER41967, and by the U.S. DOE under contract number DE-AC05-00OR22725 with UT-Battelle Corporation.
Realization of high efficiency laser stripping at the SNS accelerator needs good longitudinal overlap between H⁻ bunch and laser pulse. The default H⁻ bunch length at the interaction point is 5 times bigger than needed in order to achieve 90% stripping efficiency. Theoretical and experimental studies of longitudinal H⁻ bunch shortening are presented in this paper.

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TUYB01

Vertical Orbit-excursion Fixed Field Alternating Gradient Accelerators (V-FFAGs) and 3D Cyclotrons

cyclotron, closed-orbit, quadrupole, proton

956

S.J. Brooks
BNL, Upton, Long Island, New York, USA

FFAGs with vertical orbit excursion (VFFAGs) provide a promising alternative design for rings with fixed-field (e.g. superconducting) magnets. They have a vertical magnetic field component that increases with height in the vertical aperture, yielding a skew quadrupole focussing structure. Scaling type VFFAGs have fixed tunes and no intrinsic limitation on momentum range; they are also isochronous in the ultra-relativistic limit. Extending isochronism to lower velocities requires a slanted orbit excursion: a three-dimensional analogue of a spiral sector cyclotron from 40 to 1500MeV is developed, which is flat at low energies and acquires a slope as the protons become relativistic. This provides more stable tunes than a comparable planar cyclotron. Such machines are promising future candidates for nuclear transmutation using high average power CW beams at ~GeV energies.

Slides TUYB01 [16.187 MB]

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TUOBB01

Accelerator Physics Challenges towards a Plasma Accelerator with Usable Beam Quality

plasma, electron, laser, wakefield

961

R.W. Aßmann, J. Grebenyuk
DESY, Hamburg, Germany

Enormous progress in compact plasma accelerators has been demonstrated over the recent years in various experiments. These experiments rely on high power, pulsed lasers or short electron bunches to excite ultra-strong wakefields in plasmas. Accelerating gradients have reached several 10 GV/m up to 100 GV/m and the absolute energy gain of electron beams is in the regime of several GeV to 30 GeV. The principle and potential of plasma accelerators has been proven impressively and performance parameters are steadily improving. It is noted that particle accelerators are powerful tools that are ultimately justified by their applications in science, medicine or industry. The demonstration of useable beam quality and a realistic use case remains to be achieved for plasma accelerators. The accelerator physics challenges to arrive at this goal are analyzed and discussed.

Slides TUOBB01 [12.407 MB]

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TUPRO040

High Bandwidth Closed Orbit Control for a Fast Ramping Electron Accelerator

closed-orbit, resonance, electron, polarization

1111

J.-P. Thiry, A. Dieckmann, F. Frommberger, W. Hillert, J.F. Schmidt
ELSA, Bonn, Germany

ELSA is a fast ramping stretcher ring capable of acceleration and storage of polarized electrons with energies up to 3.2 GeV. To preserve the initial degree of polarization, the acceleration is performed by a fast energy ramp with a maximum ramping speed of 6 GeV/s. During acceleration especially the vertical orbit needs to be continuously corrected so that the vertical rms deviation does not exceed 50 μm at any time. In order to compensate the so called integer resonances, which occur at certain energies, the orbit correction system further needs to provide additional, empirically determined, harmonic field distributions. A successful application of these combined correction measures requires a considerably high bandwidth of up to some 100 Hz. In our contribution we will have a closer look at the performance and the acquired bandwidth of the correction system.

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TUPRO074

Emittance Growth due to Multiple Coulomb Scattering in a Linear Collider based on Plasma Wakefield Acceleration

scattering, plasma, emittance, electron

1211

Ö. Mete, K. Hanahoe, G.X. Xia
UMAN, Manchester, United Kingdom
O. Karamyshev, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
M. Labiche
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
M. Wing
UCL, London, United Kingdom

Alternative acceleration technologies are currently under development for cost-effective, robust, compact and efficient solutions. One such technology is plasma wakefield accel- eration, driven by either a charged particle or laser beam. However, the potential issues must be studied in detail. In this paper, the emittance growth of the witness beam through elastic scattering from gaseous media is derived. The model is compared with the numerical studies.

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TUPRO093

Numerical Study of Intrinsic Ripples in J-PARC Main-ring Magnets

simulation, damping, operation, synchrotron

1256

Y. Shirakabe, A.Y. Molodozhentsev, M. Muto
KEK, Tsukuba, Japan

Beam ripples are one of the critical problems in high power proton synchrotrons. Magnet field ripples are considered as a main origin of the beam ripples among various possible sources. Although magnet power supply ripples are generally treated as the dominating ripple source, the load circuit parameters of the magnets and their interconnections are also playing critical roles in defining the ripple amplitudes and frequencies. In this viewpoint, the magnet power supplies are treated as simplified current sources, and the ripples generated in the circuit systems are investigated both in analytical and numerical ways. One of the findings in this direction of investigation is the existence of intrinsic ripples. The intrinsic ripples occur inevitably in the synchrotron magnets, no matter how the power supplies are producing idealistic current ramp patterns. Their amplitudes are defined by the circuit parameters such as inductance and capacitance, and the ramp parameters such as ramp rates. Some of the analytical mechanisms in generating the magnet field ripples are presented as well as the studied examples.

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TUPME031

Radiation Pressure Acceleration and Transport Methods

laser, plasma, simulation, target

1422

P. Schmidt, O. Boine-Frankenheim
TEMF, TU Darmstadt, Darmstadt, Germany
O. Boine-Frankenheim, O. Boine-Frankenheim, I. Hofmann
GSI, Darmstadt, Germany
I. Hofmann
HIJ, Jena, Germany
I. Hofmann
IAP, Frankfurt am Main, Germany

Funding: HGS-HIRe for FAIR, HIC for FAIR, Technische Universität Darmstadt, FB 18 TEMF
Several projects worldwide such as LIGHT at GSI focus on laser ion acceleration. With the development of new laser systems and advances in the target production a new acceleration mechanism has become of interest: The Radiation Pressure Acceleration (RPA). An ultra short high intense laser pulse hits a very thin foil target and the emerging plasma is ideally accelerated as one piece (light sail regime). The ions reach kinetic energies up to GeV and nearly solid body densities. In this work, the distribution and transport of a RPA plasma is studied. 1D and 2D PIC simulations (software: VSim) are carried out to obtain the phase space distribution of the plasma. The results are compared to fluid models (software: FiPy and USim). A reference model an RPA plasma is obtained which is then used for advanced transport studies. Transport mechanisms (active and passive) are studied, such asμlenses and foil stacks.

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TUPME033

Scaling of TNSA-accelerated Proton Beams with Laser Energy and Focal Spot Size

laser, target, proton, experiment

4093

L. Obst, S. Kraft, J. Metzkes, U. Schramm, K. Zeil
Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiation Physics, Dresden, Germany

By focusing an ultra-short high-intensity laser pulse on a solid target, pulses of protons and other positively charged ions with energies of several 10 MeV per nucleon are generated. The properties of these particle beams such as their energy and absolute number are highly dependent on experimental conditions like laser and target parameters. In order to achieve principal comparability between different experimental campaigns at the Draco laser system at the Helmholtz-Zentrum Dresden-Rossendorf, a reference setup for the laser ion acceleration experiment was established. A configuration is sought in which proton beams of reproducible characteristics are generated. To ensure a high stability of the proton spectra, the application of longer focal length parabolas (f ~ 1000 mm) will be tested for this setup, according preparatory studies being presented in this paper.

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TUPME035

Design Study of the Laser-driven Dielectric Accelerator

laser, electron, simulation, focusing

1428

K. Koyama, M. Yoshida
KEK, Ibaraki, Japan
Y. Matsumura
University of Tokyo, Tokyo, Japan
S. Otsuki
The University of Tokyo, Tokyo, Japan
M. Uesaka
The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan

Funding: This work was partly supported by KAKENHI, Grant-in-Aid for Scientific Research (C) 24510120.
Laser driven dielectric accelerators (LDA) are vigorously studied in order to apply to various fields in recent years. Characteristics of the LDA output such as sub-micron diameter, atto-second bunch and high acceleration field are suitable for in-situ investigating the biological effects of low doses of radiation in a living cell. The output energy of 1 MeV is sufficient for sniping a cell nucleus or DNA. Although the electronic charge in the bunch is in the order of 10 fC, the tightly focused beam enable to cause a local damage in the cell. We have reported optimum structure parameters of dielectric in the nonrelativistic regime. The low acceleration efficiency of slow electrons by short laser pulses is the serious problem. The accelerator length, laser intensity, pulse width, and optical system must be adjusted to design the practical LDA. We present the design principle of the LDA for nonrelativistic electrons and present status of the pumping laser of us.

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TUPME036

Simulation Study on Electron Beam Acceleration using Coherent Cherenkov Radiation

electron, simulation, radiation, laser

1431

K. Kan, M. Gohdo, T. Kondoh, K. Norizawa, I. Nozawa, A. Ogata, T. Toigawa, J. Yang, Y. Yoshida
ISIR, Osaka, Japan
M. Hangyo
ILE Osaka, Suita, Japan
R. Kuroda, H. Toyokawa
AIST, Tsukuba, Ibaraki, Japan

Beam diagnostics for electron bunch length using spectrum analysis of multimode terahertz (THz) -wave have been studied in ISIR, Osaka University*. The multimode THz-wave was generated by coherent Cherenkov radiation (CCR)** using hollow dielectric tubes and femtosecond/picosecond electron bunches. In this study, numerical calculation of acceleration and deceleration of electron beam using multimode THz-wave was carried out.
* K. Kan et al., Appl. Phys. Lett. 99, 231503 (2011).
** A. M. Cook et al., Phys. Rev. Lett. 103, 095003 (2009).

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TUPME037

Development on On-chip Radiation Source using Dielectric Laser Accelerator

laser, electron, radiation, simulation

1434

S. Otsuki
The University of Tokyo, Tokyo, Japan
K. Koyama, M. Yoshida
KEK, Ibaraki, Japan
Y. Matsumura
University of Tokyo, Tokyo, Japan
S. Mima
RIKEN, Japan
M. Uesaka
The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan

Funding: This work was partly supported by KAKENHI, Grant-in-Aid for Scientific Research (C) 24510120.
One of the state-of-the-art acceleration schemes, where high intensity laser pulses are modulated by dielectric grating structure such as quartz to accelerate charged particles, is dielectric laser acceleration (DLA)*. The difference of our DLA concept from other schemes is installation of a prism: the tilted wave-front in a prism shape refractive medium leads the suitable delay to match the phase advance of the electron beam. We plan to apply this method to build an on-chip radiation source which can hit and damage target elements of the cells. Such an application is useful in radiation biology, i.e., for investigation on bystander effects. The x-rays with small radius and adequate intensity required for this goal can be obtained using sub-micron beams from the small accelerating structure at high repetition rate (such as 50 kHz). In addition, the mass productivity of the DLA based on the consumer-grade laser and the photolithography has advantage compared to the conventional RF accelerator using high power klystrons. We will present field simulation and preliminary experimental results for demonstration on our concept of DLA.
* Demonstration of electron acceleration in a laser-driven dielectric microstructure, Nature 2013
** Laser-Based Acceleration of Nonrelativistic Electrons at a Dielectric Structure, Phys. Rev. 2013

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TUPME040

Drive Beam Break-up Control and Practical Gradient Limitation in Collinear Dielectric Wakefield Accelerators

wakefield, simulation, linac, quadrupole

1443

C. Li, W. Gai, J.G. Power, A. Zholents
ANL, Argonne, Illinois, USA
C.-J. Jing
Euclid TechLabs, LLC, Solon, Ohio, USA
C. Li, C.-X. Tang
TUB, Beijing, People's Republic of China

Dielectric wakefield accelerator (DWA) concept has gained significant attention for the need of the future large scale facilities. For a practical machine, one needs to overcome a major challenge for the DWA that is the efficient energy extraction and stable propagation at the same time for the drive beam. Typically, a slightly off axis beam become unstable in the dielectric channel due to transverse wakefield excitation, that could be controlled if a strong external alternating magnetic focusing channel applied at the same time. However, there is limitation on the practical magnetic field in the focusing channel (typically < 1 Tesla), thus imposing operating point for the DWA. In this article, we explore the operating point of the DWA for various structure frequencies and drive beam charge, particularly on the gradient and total acceleration distance, and provide guidance on the DWA design.

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TUPME042

Planned High-gradient Flat-beam-driven Dielectric Wakefield Experiments at the Fermilab’s Advanced Superconducting Test Accelerator

wakefield, emittance, experiment, controls

1451

F. Lemery, D. Mihalcea, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
P. Piot, J. Zhu
Fermilab, Batavia, Illinois, USA
J. Zhu
CAEP/IFP, Mainyang, Sichuan, People's Republic of China

In beam driven dielectric wakefield acceleration (DWA), high-gradient short-wavelength accelerating fields are generally achieved by employing dielectric-lined waveguides (DLWs) with small aperture which constraints the beam sizes. In this paper we investigate the possibility of using a low-energy (50-MeV) flat beams to induce high-gradient wakes in a slab-symmetric DLW. We demonstrate via numerical simulations the possibility to produce axial electric field with peak amplitude close to 0.5 GV/m. Our studies are carried out using the Fermilab's Advanced Superconducting Test Accelerator (ASTA) photoinjector beamline. We finally discuss a possible experiment that could be performed in the ASTA photoinjector and eventually at higher energies.

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TUPME043

Temporal Electron-bunch Shaping from a Photoinjector for Advanced Accelerator Applications

space-charge, laser, wakefield, gun

1454

F. Lemery, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
P. Piot
Fermilab, Batavia, Illinois, USA

Advanced-accelerator applications often require the production of bunches with shaped temporal distributions. An example of sought-after shape is a linearly-ramped current profile that can be improve the transformer ratio in beam-driven acceleration, or produce energy-modulated pulse for, e.g., the subsequent generation of THz radiation. Typically, such a shaping is achieved by manipulating ultra-relativistic electron bunches. In this contribution we discuss the possibility of shaping the bunch via photoemission and demonstrate using particle-in-cell simulations the production of MeV electron bunches with quasi-ramped current profile.

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TUPME045

Development of a High-Energy Short-pulse 5-μm Parametric Source for Dielectric Laser Acceleration

laser, detector, operation, optics

1460

G. Xu, I. Jovanovic, S.F. Wandel
Penn State University, University Park, Pennsylvania, USA

A compact, high-peak-power 5-μm laser source with pulse duration of sub-100 fs has been designed and being constructed for pumping a dielectric photonic structure to produce an acceleration gradient of order GV/m in dielectric laser acceleration. Breakdown of dielectric structure induced by multiphoton ionization can be mitigated by adopting long wavelength driver laser. Since the dielectric structure scales with the laser wavelength, fabrication tolerances for dielectric structure are relaxed as well. The 5-μm laser source is based on two cascaded optical parametric amplifiers (OPA): a 2-μm BBO OPA with a mixed phase matching scheme is used as a pump source, and a type-I phase-matched ZGP OPA is designed to produce sub-mJ, <100 fs 5-μm laser pulses. The two-stage 2-μm OPA is pumped by a Ti:sapphire amplifier and produces pulse energy of ~2.2 mJ with a pulse duration of 42 fs (~6 optical cycles), and excellent pulse stability and beam quality. Preliminary result of ~50 μJ pulse energy at 5-μm is demonstrated by using single-stage ZGP OPA, and an improved two-stage OPA scheme for production of higher pulse energy at 5-μm is under development.

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TUPME052

Enhanced Laser Ion Acceleration based on Near-Critical Density Plasma Lens

plasma, laser, target, electron

1483

Y.X. Geng, J.E. Chen, L.R.F. Li, Y.H. Li, Q. Liao, C. Lin, L.H.Y. Lu, Y.R. Lu, H. Wang, X.Q. Yan, Z.X. Yuan, S. Zhao, W.B. Zhao, Y.Y. Zhao, K. Zhu, B.Y. Zou
PKU, Beijing, People's Republic of China

The laser prepulse has large effect on ion acceleration driven by high power laser pulse. Recently, simulations show that with proper prepulse parameters, a near critical density pre-plasma can be generated in the front target. When the main laser pulse propagating in this pre-plasma, it can experience transverse Self-focusing, longitudinal profile steepening and prepluse cleaning at the same time, meaning its quality is spontaneously improved by this “plasma lens”.The effects can greatly improve the energy coupling efficiency of laser pulse into accelerated ions. A 3mJ Ti-Sapphire laser system has been built at PKU in order to experimentally study the pre-pulse effect on a solid target. Fluid simulation show that, after hundreds of picoseconds radiated with this laser pulse, the pre-plasma in front of the target will expand to near critical density with tens of micron scale length, which is suitable as a plasma lens to improve the ion acceleration. A laser interferometer system is built to measure the scale length and density evolution of plasma and the optimum condition of the pre-plasma has been searched using both Aluminum target and home-made DLC target.
H.Y.Wang et al, Laser shaping of a relativistic intense, short Gaussian pulse by a plasma lens, PRL, 107,265002, 2011

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TUPME055

Room-temperature Burst-mode GHz and THz Pulse-train Photoinjector

electron, laser, cathode, bunching

1492

F.H. Chao, C.H. Chen, K.Y. Huang, Y.-C. Huang, Y.C. Wang, M.H. Wu
NTHU, Hsinchu, Taiwan
P.J. Chou
NSRRC, Hsinchu, Taiwan

A photoinjector usually generates an electron pulse with few ps pulse duration repeating at 10-100 Hz. The low-pulse rate limits the data rate in a number of applications. Although high-repetition-rate operation is possible from a superconducting accelerator, the high cost and complexity of a superconducting system prevent it from being widely used. In this paper, we present our study toward a burst-mode GHz/THz pulse train photoinjector operating at room temperature. For the GHz operation mode, we self-develop a driver laser system, generating tens of laser pulses at 2.856 GHz in an adjustable 5-10 ns temporal envelope repeating at 10 Hz. Upon illuminating the photocathode with the driver laser, our S-band photoinjector (supported by Tsing Hua University, Beijing) is to generate a GHz electron pulse train with the same temporal structure as that of the driver laser pulses. For the THz operation mode, we illuminate the photocathode with two lasers, one being a typical UV gun-driver laser at 260 nm and the other being a mid-infrared laser at 100 THz. The UV laser induces photoemission and the infrared laser gates the emission current at 100 THz by virtue of the Schottky effect.

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TUPME056

Improving Ion and Electron Beam Characteristics within LA³NET

laser, electron, photon, simulation

1495

C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom

Funding: This project has received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement no 289191.
Lasers are widely used at accelerator and light source facilities for beam generation, acceleration and optimization. Research within LA³NET focuses on laser-based particle sources (photo injectors and laser ion sources), laser acceleration, and laser-based beam diagnostics. This project was recently selected as a ‘success story’ by the European Commission for its research achievements. This paper presents selected numerical and experimental results. From HZDR results of electron transport simulations in their new SRF gun II cavity, super-conductive solenoid and downstream accelerators are shown. The results from optimization studies into asymmetric grating structures obtained at the University of Liverpool are also presented, along with initial results from studies into novel diagnostics for high intensity proton beams at CERN and low energy electron beams at KIT. Finally, the events organized by the consortium to date and future plans are summarized.

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TUPME060

Simulation Analysis on Micro-Bunched Density Modulation from a Slit-Masked Chicane

simulation, electron, bunching, dipole

1509

Y.-M. Shin, P. Piot, C.R. Prokop
Northern Illinois University, DeKalb, Illinois, USA
D.R. Broemmelsiek, E.R. Harms, A.H. Lumpkin, J. Ruan, J.C.T. Thangaraj
Fermilab, Batavia, Illinois, USA

Funding: This work was supported by the DOE contract No. DEAC02-07CH11359 to the Fermi Research Alliance LLC.
Pre-bunching a beam at a resonance condition with an accelerating structure vastly improves performance of beam-driven accelerators and undulators since it enhances a beam-wave coupling. We plan to test a slit-mask micro-buncher at the chicane of Fermilab-ASTA 50 MeV beamline in the effort of advanced accelerator research. With the chicane design parameters (bending angle (alpha) of 18 degree, R56 ~ - 0.18 m, and bending radius of ~ 0.78 m), analytic model showed that a slit-mask with W (period) = 900 um and a (aperture width) = 300 um (30 % transparency) generates 100 um spaced micro-bunches with 5 ~ 6 % correlated energy spread. Two kinds of combined beamline simulation, CST-PS+Impact-Z and Elegant+Shower, including space charge and CSR effects, showed that a 900 um spaced, 300 um wide slits placed in the middle of chicane splits 20 pC – 1 nC bunches into ~ 100 um spaced micro-bunches. It is possible that a further optimization of mask design creates sub-100 fs micro-bunches, which is currently under development.
*[1] NIM A 375, 597 (1996)
[2] PRL 101, 054801 (2008)
[3] Y.-E Sun, P. R. G. Piot, FEMILAB-CONF-08-408-APC
** ASTA: Advanced Superconducting Test Accelerator

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TUPME061

Ultra-High Gradient Beam-Driven Channeling Acceleration in Hollow Crystalline Media

plasma, electron, target, scattering

1512

Y.-M. Shin, T. Xu
Northern Illinois University, DeKalb, Illinois, USA
G. Flanagan
Muons, Inc, Illinois, USA
E.R. Harms, J. Ruan, V.D. Shiltsev
Fermilab, Batavia, Illinois, USA

Since the recent discovery of the Higgs boson particle, there is an increasing demand in Energy Frontier to develop new technology for a TeV/m range of acceleration gradient. The density of charge carriers, ~ 10²⁴ – 10²⁹ m^-3, of crystals is significantly higher than that of a plasma gas, and correspondingly in principle wakefield gradients of up to 0.1 - 10 TV/m are possible. Our simulations (VORPAL and CST-PIC) with Fermilab-ASTA* beam parameters showed that micro-bunched beam gains energy up to ~ 70 MeV along the 100 um long channel under the resonant coupling condition of the plasma wavelength, ~ 10 um. Also, with lowering a charge, electron bunches channeling through a high-density plasma medium have higher energy gain in a hollow channel than in a uniformly filled cylinder, which might be attribute to lower scattering ratios of the tunnel structure. The numerical analysis implied that synthetic crystalline plasma media (e.g. carbon nanotubes) have potential to mitigate constraint of bunch charges required for beam-driven acceleration in high density plasma media. The channeling acceleration** will be tested at the ASTA facility, once fully commissioned.
* ASTA: Advanced Superconducting Test Accelerator
** [1] T. Tajima and M. Cavenago, PRL 59, 13(1987)
[2] P. Chen and R. Noble, SLAC-PUB-7402(1998)
[3] V.Shiltsev, Physics Uspekhi 55, 965(2012)

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TUPME064

Laser-driven Acceleration with External Injection at SINBAD

plasma, laser, injection, simulation

1515

J. Grebenyuk, R.W. Aßmann, U. Dorda, B. Marchetti
DESY, Hamburg, Germany

One of the important milestones to make plasma acceleration a realistic technology for user-applications is demonstration of bunch acceleration inside a plasma wake with minimal degradation of its quality. This can be achieved by external injection of beams into a plasma accelerator. SINBAD is a proposed dedicated accelerator research and development facility at DESY where amongst other topics laser-driven wakefield acceleration with external injection of ultra-short bunches will be exploited. To minimise energy-spread growth the bunch should occupy a small fraction of the plasma wavelength. In addition it has to be longitudinally synchronised with the laser driver to high accuracy. To avoid emittance growth the beam Twiss parameters have to be matched to the intrinsic beta-function of the plasma. To facilitate matching and synchronisation, acceleration at low plasma densities can be advantageous. We present a preparatory feasibility study for future plasma experiments at SINBAD using simulations with the particle-in-cell code OSIRIS. Field-gradient scaling laws are presented together with parameter scans of externally injected bunch, such as its injection phase, charge and length.

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TUPRI009

Study of Resonance Crossing in Non-scaling FFAGs using the S-POD Linear Paul Trap

resonance, ion, dipole, experiment

1571

D.J. Kelliher, S. Machida, C.R. Prior, S.L. Sheehy
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
K. Fukushima, K. Ito, K. Moriya, H. Okamoto, T. Okano
HU/AdSM, Higashi-Hiroshima, Japan

Experiments on EMMA have shown that with rapid acceleration (~10 turns) a linear non-scaling FFAG can accelerate through several integer tunes without detrimental effects on the beam [1]. Proton and ion applications such as hadron therapy will necessarily have a slower acceleration rate, so their feasibility depends on how harmful resonance crossing is in this regime. A simple and useful tool to answer such fundamental questions is the S-POD linear Paul trap at Hiroshima University, which can be set up to simulate the dynamics of a beam in an FFAG. We report here results of experiments to explore different resonance crossing speeds, quantify beam loss and study nonlinear effects. We also discuss the implications of these experimental results in terms of limits on acceptable acceleration rates and alignment errors.
[1] S.Machida et al, Nature Physics, N8, 243-257 (2012)

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TUPRI031

A Precise Beam Dynamics Model of the PSI Injector 2 to Estimate the Intensity Limit

space-charge, cyclotron, simulation, extraction

1630

A.M. Kolano, R.J. Barlow
University of Huddersfield, Huddersfield, United Kingdom
A. Adelmann, C. Baumgarten
PSI, Villigen PSI, Switzerland

We describe a precise beam dynamics model of the production set up of the Injector 2 Cyclotron at the Paul Scherrer Institut (PSI). Injector 2 is a 72 MeV separate-sector cyclotron producing a high intensity proton beam up to 2.7 mA CW, which is then injected into the 590 MeV Ring Cyclotron. The model includes space charge and is calculated for optimised matched initial conditions. It has been verified with measurements. Based on this model we estimate the limits to the intensity obtainable from Injector 2. The precise beam dynamics model is based on the OPAL (Object Oriented Parallel Accelerator Library) simulation code, a tool for charged-particle optics calculations in large accelerator structures and beam lines including 3D space charge.

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TUPRI051

Comparison between Measurements and Orbit Code Simulations for Beam Instabilities due to Kicker Impedance in the 3-GeV RCS of J-PARC

simulation, impedance, injection, kicker

1683

P.K. Saha, H. Harada, N. Hayashi, H. Hotchi, Y. Shobuda, F. Tamura, M. Yamamoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

The transverse impedance of the extraction kicker magnets is the most dominant beam instability source in the 3-GeV Rapid Cycling Synchrotron of J-PARC. The instability occurs when chromaticity is fully corrected during acceleration but on the other hand no instabilities are observed for a full chromatic correction only at the injection energy even for a beam power up to 500 kW. However, the situation may change for a beam power of 1 MW and also for the upgraded injection beam energy from the present 181 MeV to the 400 MeV, as space charge effect in the non-relativistic region is believed to suppress the growth rate of beam instability. In order to study the kicker impedance in detail, recently we have introduced measured time dependent impedance source in the ORBIT simulation code in a realistic manner. The ORBIT code itself has also been well upgraded and given realistic features for application to synchrotrons. We have also carried out a systematic experimental study for a maximum beam power of 500 kW. In this paper, a detail comparison between measurements and corresponding simulations including 1 MW simulation results are presented.

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WEXB01

Breaking the 70 MeV Proton Energy Threshold in Laser Proton Acceleration and Guiding Beams to Applications

laser, target, proton, ion

1886

M. Roth, S. Bedacht, S. Busold, O. Deppert, G. Schaumann, A. Tebartz, F. Wagner
TU Darmstadt, Darmstadt, Germany
V. Bagnoud, A. Blazevic, D. Schumacher
GSI, Darmstadt, Germany
C. Brabetz
IAP, Frankfurt am Main, Germany
T.E. Cowan
HZDR, Dresden, Germany
K. Falk, A. Favalli, J.C. Fernandez, C. Gautier, C.E. Hamilton, R.P. Johnson, K. Schoenberg, T. Shimada, G.A. Wurden
LANL, Los Alamos, New Mexico, USA
M. Geißel, M. Schollmeier
Sandia National Laboratories, Albuquerque, New Mexico, USA
D. Jung
Queen's University of Belfast, Belfast, Northern Ireland, United Kingdom
F. Kroll
Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiation Physics, Dresden, Germany

This talk covers recent developments in laser plasma ion acceleration describing the technological challenges in breaking of energy threshold of 70 MeV. The presentation also highlights the recent experimental achievements towards laser ion acceleration and transport in the LIGHT collaboration.

Slides WEXB01 [15.155 MB]

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WEOAB02

Wide-band Induction Acceleration in the KEK Digital Accelerator

induction, ion, synchrotron, experiment

1893

T. Yoshimoto, X. Liu, K. Takayama
TIT, Yokohama, Japan
T. Adachi, K. Takayama
Sokendai, Ibaraki, Japan
T. Adachi, T. Arai, E. Kadokura, T. Kawakubo, X. Liu, K. Okamura, S. Takano, K. Takayama, T. Yoshimoto
KEK, Ibaraki, Japan
H. Asao, Y. Okada
NETS, Fuchu-shi, Japan
M. Hirose, H. Kobayashi
Tokyo City University, Tokyo, Japan

Induction synchrotron can accelerate any ion species directly to higher energy without a large pre-accelerator, due to its intrinsic nature that there is no frequency band-width limitation below 1 MHz. KEK digital accelerator (DA) is a small scale prototype of fast cycling induction synchrotron. Recently it has been confirmed that heavy ion beams of mass to charge ratio A/Q = 4 are stably accelerated from 200 keV to a few tens of MeV in this accelerator ring*, where the revolution frequency changes from82 kHz to 1 MHz. Acceleration and beam confinement are separately realized by pulse voltages generated in induction cells (1 to 1 pulse transformers) driven by the switching power supply (SPS)**. Everything is simply maneuvered by controlling of gate signals of solid-state switching elements employed in the SPS. For this purpose, the fully programmed acceleration control system based on the FPGA has been developed. In this paper, the wide-band induction acceleration is presented with experimental results. Further possibilities of beam handling in the induction synchrotron, such as super bunch and novel beam handling techniques, are discussed.
* K.Takayama et al., to be submitted to Phys. Rev. Lett. (2013).
** T.Iwashita et al., Phys. Rev. ST-AB 14, 071301(2011).

Slides WEOAB02 [8.935 MB]

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WEOAB03

Linear Electron Acceleration in THz Waveguides

electron, linac, laser, accelerating-gradient

1896

E.A. Nanni, W.S. Graves, K.-H. Hong, W.R. Huang, F.X. Kärtner, KR. Ravi, L.J. Wong
MIT, Cambridge, Massachusetts, USA
A. Fallahi, F.X. Kärtner
CFEL, Hamburg, Germany
R.J.D. Miller
DESY, Hamburg, Germany
G. Moriena
University of Toronto, Toronto, Ontario, Canada

Funding: Supported by DARPA N66001-11-1-4192, CFEL DESY, DOE DEFG02-10ER46745, DOE DE-FG02-08ER41532, ERC Synergy Grant 609920 and NSF DMR-1042342.
We report the first experimental demonstration of linear electron acceleration using an optically generated single cycle THz pulse centered at 0.45 THz. 7 keV of acceleration is achieved using 10 microJ THz pulses in a 3 mm interaction length. The THz pulse is produced via optical rectification of a 1.2 mJ, 1 micron laser pulse with a 1 kHz repetition rate. The THz pulse is coupled into a dielectric-loaded circular waveguide with 10 MeV/m on-axis accelerating gradient. A 25 fC input electron bunch is produced with a 60 keV DC photo-emitting cathode. The achievable accelerating gradient in the THz structures being investigated will scale rapidly by increasing the IR pulse energy (100 mJ - 1 J) and correspondingly the THz pulse energy. Additionally, with recent advances in the generation of THz pulses via optical rectification, in particular improvements to efficiency and generation of multi-cycle pulses, GeV/m accelerating gradients could be achieved. An ultra-compact high-gradient THz accelerator would be of interest for a wide variety of applications.

Slides WEOAB03 [7.185 MB]

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WEPRO061

Optimization of the SIS18 Injector Operation for FAIR

operation, experiment, controls, space-charge

2088

D. Ondreka, H. Liebermann, B.R. Schlei
GSI, Darmstadt, Germany

In the FAIR accelerator complex, the existing synchrotron SIS18 will serve as an injector, supplying intense beams of heavy ions and protons for further acceleration in the synchrotron SIS100. In order to satisfy the intensity requirements for FAIR, SIS18 has to be operated routinely at the space charge limit. Particularly demanding requirements arise from the operation with medium charge state heavy ions due to the dynamic vacuum created by ions lost through charge exchange reactions. It is therefore crucial to avoid losses in SIS18 as much as possible while confining unavoidable losses onto low desorption surfaces. In this contribution we report on the ongoing activities related to minimizing the losses by means of a better quantitative understanding and control of the beam. This includes the development of more accurate theoretical models, benchmarked with machine experiments, as well as the practical integration of the models into the control system, using beam instrumentation data in the calculation of set values whenever possible.

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WEPRO062

Reacceleration of Ion Beams for Particle Therapy

synchrotron, ion, extraction, operation

2091

C. Schömers, R. Cee, E. Feldmeier, M. Galonska, Th. Haberer, A. Peters, S. Scheloske
HIT, Heidelberg, Germany

At the Heidelberg Ion-Beam Therapy Centre (HIT) cancer patients are treated using the raster-scanning method. A synchrotron provides pencil beams in therapy quality for 255 energy steps per ion type allowing to vary the penetration depth and thus to irradiate tumors slice-by-slice. So far, changing the beam energy necessitates a new synchrotron cycle, including all phases without beam extraction. As the no. of ions that can be accelerated in the synchrotron usually exceeds the required no. of ions for one energy slice, treatment time could be significantly reduced by reaccelerating or decelerating the remaining ions to the next energy level. By alternating acceleration and extraction phases several slices could be irradiated with only short interruptions. Therefore the reacceleration of a transversally blown up beam – due to RF-knockout extraction – must be investigated, beam losses have to be minimized. To estimate the benefit of this operation mode, treatment time has been simulated and compared to the time achieved in the past. A reduction of up to 65% is possible and more patients can be treated! Simulations and first tests of a reaccelerated and extracted beam are presented.

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WEPRI030

Multipactor Simulation on Superconducting Spoke Cavity for Laser Compton Scattered Photon Sources

multipactoring, cavity, simulation, electron

2543

Y. Iwashita, H. Fujisawa, H. Tongu
Kyoto ICR, Uji, Kyoto, Japan
R. Hajima, R. Nagai, M. Sawamura
JAEA, Ibaraki-ken, Japan
T. Kubo
KEK, Ibaraki, Japan

Funding: This work is supported by Photon and Quantum Basic Research Coordinated Development Program.
Superconducting spoke cavity for laser Compton scattered (LCS) photon sources is under development. The operating frequency is 325-MHz to accelerate electron beam for the LCS sources, where the size of the spoke cavity is less than a elliptical cavities with the same frequency. Because of the complicated shape of the cavity, it may be suffered from a strong multipactor effect. The recent results on the multipactor analysis will be presented.

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WEPRI090

Cyclotron C235-V3 for Dimitrovgrad Hospital Center of the Proton Therapy

cyclotron, proton, extraction, focusing

2703

S.A. Kostromin, S. Gurskiy, G.A. Karamysheva, M.Y. Kazarinov, S.A. Korovkin, S.P. Mokrenko, N.A. Morozov, A.G. Olshevsky, V.M. Romanov, E. Samsonov, N.G. Shakun, G. Shirkov, S.G. Shirkov, E. Syresin
JINR, Dubna, Moscow Region, Russia
P. Cahay, Y. Jongen, Y. Paradis
IBA, Louvain-la-Neuve, Belgium

JINR-IBA C235-V3 isochronous cyclotron for 1st Russian hospital center of the proton therapy has been assembled and tested. Shimming of the magnetic field, optimization of the acceleration modes and testing with the extracted proton beam were done in frame of this work. The paper presents experimental results of the beam dynamics in the accelerator. Proton transmission from radius 30cm to 103cm is 72% without beam cutting diaphragms. The extraction efficiency is 62%. This cyclotron is a substantially modified version C235-V3 of the IBA C235 serial cyclotron. C235-V3 has the improved extraction system which was constructed and tested. This system allows raise the extraction efficiency up to 77% from 50% in comparison with serial C235. Special mapping system (for Br-component) of the magnetic field was developed and constructed by JINR for the shimming of the Br-field in the middle plane of the cyclotron. Total efficiency of the machine is 45%. Further improvement of the parameters expected after final tuning of the cyclotron in Dimitrovgrad.

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THPRO070

Beam Dynamics Simulations in Cyclotron C230 Considering Imperfections of Magnetic Field Radial Component

cyclotron, proton, simulation, focusing

3038

E. Samsonov, S.A. Kostromin, N.A. Morozov, E. Syresin
JINR, Dubna, Moscow Region, Russia

Simulations concern to a beam axial motion in the IBA cyclotron C230 that is a base facility in several medical centers worldwide. Because of small axial focusing of the beam in a center of the cyclotron the radial component of magnetic field imperfections leads to additional proton losses. Measured maps of the axial and radial components of magnetic field were used in the simulations. It was found that the radial component with value 5-10 G in the center and approximately 2 G in the main region of acceleration leads to decrease of the resulting beam intensity by about two times and to increase the beam axial width by 25% as well. Simulations define the requirements to the experimental radial component shaping for the next cyclotrons of this series. Providing these requirements will ensure an absence of the additional proton losses due to the axial motion perturbations.

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THPRO073

Longitudinal Acceptance Evaluation from Hamiltonian

cavity, linac, simulation, lattice

3047

E. Laface
ESS, Lund, Sweden

An RF cavity is designed around a reference particle; if the energy or the phase of a real particle are too far from the reference, the particle is lost. The widest area of energy-phase that allows a particle to be transported by the cavity is called acceptance of the cavity. In simulations the acceptance is evaluated tracking several particles with different energies and phases and marking when a particle is transmitted or lost. This process can be time consuming because of the large amount of tracked particles requested to characterise the cavity acceptance. In this paper we propose an alternative method to evaluate the acceptance studying directly the Hamiltonian associated to the cavity.

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THPRO082

Observation of Coherent Instability in the CERN PS Booster

quadrupole, closed-orbit, booster, simulation

3076

M. McAteer, C. Carli, V. Forte, G. Rumolo, R. Tomás
CERN, Geneva, Switzerland

Funding: This project has been supported by a Marie Curie Early Initial Training Network Fellowship of the European Community's Seventh Framework Programme, contract number (PITN-GA-2011-289485-OPAC).
At high intensities and at a certain working point an instability develops in the CERN PS Booster, and large coherent transverse oscillations and beam loss occur. The coherent oscillations and beam loss can be effectively controlled with the transverse damper system, but the origin of the instability is not well-understood. Recent measurements with the PSB's new trajectory measurement system have provided some insight into the nature of this instability, and these observations are presented here.

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THPRO084

Beam Dynamics Observations of Slow Integer Tune Crossing in EMMA

simulation, lattice, synchrotron, injection

3082

J.M. Garland, H.L. Owen
UMAN, Manchester, United Kingdom
D.J. Kelliher, S. Machida
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
B.D. Muratori
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

When the betatron tune is an integer in a cyclical accelerator, dipole-field errors can drive the coherent addition of betatron amplitude to the bunch eventually causing particle loss. Transverse integer tune crossing in a linear non-scaling FFAG is inevitable due to finite chromaticity. In EMMA (Electron Machine with Many Applications), as many as 6 integers may be crossed is as little as 6 turns at maximum acceleration over the 10 – 20 MeV energy range. This fast integer tune crossing, of the order 1 integer per turn, was shown to have little effect on the coherent amplitude growth and charge loss rate. Slower acceleration inside an RF bucket in EMMA allowed the experimental exploration of slower integer tune crossing speeds, of the order of a factor ten slower. The effect on the coherent oscillation amplitude was observed and the charge loss at integer tune crossings indicated resonant effects on the bunch. Simulations in Zgoubi allowed a more detailed analysis and the mechanism of slower resonance crossing in a non-scaling FFAG is discussed, including the importance of coupled longitudinal-transverse decoherence on the effective emittance.

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THPRO088

Optimization of the pp AGS Zgoubi Model in the Low Energy Range

resonance, simulation, emittance, betatron

3089

Y. Dutheil, H. Huang, F. Méot, N. Tsoupas
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
At low energy the AGS lattice is strongly deformed by the two strong helical snakes, required to preserve the polarization. In addition to the complex, highly non-linear field featured by the two snakes, multiple non-linear coupling resonance lines are crossed by the beam in this region. Hence, the use of realistic models for the Siberian snakes is critical for the simulation of the early part of the AGS acceleration cycle. The AGS Zgoubi model uses direct tracking through OPERA field maps of the two snakes. While many processes may be obnoxious to both beam and spin dynamics in this region, it is critical to use a realistic model of the AGS at low energy. This paper presents the current model used and some of the challenges recently faced. We will also compare experimental beam dynamics results to those predicted by the Zgoubi model.

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THPRO089

New Tune Jumps Scheme in the Low Energy Part of the AGS Cycle

polarization, resonance, simulation, hardware

3092

Y. Dutheil, L. Ahrens, J.W. Glenn, H. Huang, F. Méot, V. Schoefer
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
During the early part of the acceleration of polarized protons, due to strong optical deformations of the lattice, the tune cannot be placed in the spin gap and the first two vertical intrinsic resonances are crossed. Recent multiparticle trackings using the Zgoubi code show that the spin resonances around Gg=5 could cause as much as 5% loss of polarization. The slow acceleration rate, the two vertical and two horizontal intrinsic spin resonances can contribute to the depolarization in the region. While in the current scheme only the two horizontal intrinsic resonances are jumped, it was proposed to use the tune jumps system to also accelerate the crossing of the two weak vertical intrinsic resonances and improve the polarization transmission through this region. We show the design of this new tune jumps scheme and the expected polarization gains expected from multiparticles Zgoubi simulations. We also compare experimental measurements of the polarization transmission to the Zgoubi simulations.

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THPRO090

Energy Calibration and Tune Jumps Efficiency in the pp AGS

polarization, timing, resonance, extraction

3095

Y. Dutheil, L. Ahrens, H. Huang, F. Méot, A. Poblaguev, V. Schoefer, K. Yip
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The AGS tune jump system consists of two fast quadrupoles used to accelerate the crossing of 82 horizontal intrinsic spin resonances. The fast tune jump of ΔQh=+0.04 within 100 μs imposes perfect localization of each of the 82 resonant conditions. Imperfect timing of the tune jumps results in lower efficiency of the system and lower transmission of the polarization through the AGS acceleration cycle. Investigations during the end of the pp AGS Run13 revealed weaknesses in the energy measurement at high energy, causing less than optimal timing of the tune jumps. A new method based on continuous polarization measurement to determine the energy during the acceleration cycle has been developed. Strong operational constraints were taken into account to provide a convenient system of energy measurement. This is also used to calibrate the usual determination of the energy based on revolution frequency of the beam or measured dipole magnetic field. This paper shows the tools developed and the results of the first tests during the AGS Run 14. Simulations of the expected tune jumps efficiency using the AGS Zgoubi model are also presented and compared to experimental results.

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THPRO102

Generation of RF Frequency and Phase References on the FAIR Site

controls, electronics, hardware, cavity

3131

B. Zipfel, H. Klingbeil, U. Laier, K.-P. Ningel, S. Schäfer, C. Thielmann
GSI, Darmstadt, Germany
U. Hartel, H. Klingbeil
TEMF, TU Darmstadt, Darmstadt, Germany
D.E.M. Lens
TU Darmstadt, RTR, Darmstadt, Germany

Based on the Bunch Phase Timing System (BuTiS)* local analog radio frequency reference signals (RF references) like the particle revolution frequency and their multiple harmonics will be generated. These references are used to control the phase of the accelerator cavities to altering harmonics of the bunch revolution frequency. Delay or phase shifts from the FAIR-Center to references at the BuTiS endpoints are already compensated by the BuTiS receivers. Phase shifts from the RF reference generators to LLRF electronics can be compensated by controlling the output phases of the DDS modules of the RF references. However phase shift delays of multiple harmonics at the same interconnecting electrical path are not identical at the same time. Configurable electronics** manage phase calibration of the RF references to their endpoints. Calibration may depend on frequency and harmonic of the RF reference, aging as well as on thermal effects. The electrical length and impedance of interconnecting cables for phase control loops can be compensated. This is an important feature, in particular if control loops are switched between different harmonic frequencies.
*B. Zipfel, P. Moritz: Proc. IPAC 2011, San Sebastian
**S. Schäfer, et al.: Proc. IPAC 2013, Shanghai

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THPME027

Development of the injector II RFQ for China ADS project

rfq, cavity, linac, proton

3280

Z.L. Zhang, Y.H. Guo, Y. He, H. Jia, C.X. Li, Y. Liu, L. Lu, G. Pan, A. Shi, L.B. Shi, L.P. Sun, W.B. Wang, X.W. Wang, J.X. Wu, Q. Wu, X.B. Xu, B. Zhang, J.H. Zhang, H.W. Zhao, T.M. Zhu
IMP, Lanzhou, People's Republic of China
M.D. Hoff, A.R. Lambert, D. Li, J.W. Staples, S.P. Virostek
LBNL, Berkeley, California, USA
C. Zhang
GSI, Darmstadt, Germany

As one of the main components of the injector II of China ADS LINAC project, an RFQ working at 162.5MHz is used to accelerate proton beams of 15mA from 30 keV to 2.1 MeV. The four vane RFQ has been designed in collaboration with Lawrence Berkeley National Laboratory and built at the workshop of the Institute of Modern Physics, Chinese Academy of Sciences (IMP, CAS). Low power test of the cavity have been completed, and it shows the field flatness is within ±1% and the unloaded Q is 12600. RF conditioning has been completed, results of preliminary beam test show the output beam energy is 2.16 MeV with energy spread of 3.5% and the transmission efficiency is 97.9%. Continuous wave (CW) beam of 2.3 mA has been accelerated for more than one hour.

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THPME029

Upgrade of Heavy Ion Injector for ITEP-TWAC Facility

ion, simulation, heavy-ion, focusing

3283

V. Andreev, N.N. Alexeev, A.I. Balabin, M.M. Kats
ITEP, Moscow, Russia
A.A. Metreveli
MEPhI, Moscow, Russia

A new scheme of heavy ion injector I-3 designed for improvement of accelerated beam parameters has been proposed for ITEP-TWAC Facility. It is based on the usage of two quarter-wave double gap resonators operated on 5 MHz with accelerating voltage of 3 MV per gap. Existing 2.5 MHz double gap resonator will be retuned for operational frequency of 5 MHz and new additional one will be built. The new injector optimized for acceleration of heavy ions with A/Z in the range of 3-10 will allow accelerating any ions from C to U with beam current up to10 mA. Results of both electrodynamics and beam dynamics simulations of the accelerating structures are presented.

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THPME032

Beam Transfer Studies for LINCE Experimental Areas

optics, beam-transport, quadrupole, linac

3292

L. Acosta, C. Bonțoiu, I. Martel, A.R. Pinto Gómez, A.C.C. Villari
University of Huelva, Huelva, Spain
J. Lucas
Elytt Energy, Madrid, Spain
A.C.C. Villari
FRIB, East Lansing, Michigan, USA

Funding: Work partially supported by the Spanish Government (MINECO-CDTI) under program FEDER INTERCONNECTA.
Beam transport from the exit of the LINCE linac to experimental areas has been optimized for a few ion species using transfer matrix calculations performed in MADX. An alpha spectrometer based on a double-bending achromat lattice has been used as dispersion suppressor and particle tracking studies have been carried out in GPT along it and the three beamlines. Realistic quadrupole and dipole magnet design achieved in Comsol enabled accurate particle tracking studies and evaluation of the beam parameters delivered at the target.

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THPME067

Air Stripper for Intense Heavy Ion Beams

target, ion, cyclotron, heavy-ion

3388

H. Imao
RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama, Japan
M. Fujimaki, N. Fukunishi, H. Hasebe, O. Kamigaito, M. Kase, H. Kuboki, H. Okuno, Y. Yano
RIKEN Nishina Center, Wako, Japan

Intensity upgrade of very heavy ions such as uranium or xenon beams is one of the main concerns at the RIKEN Radioactive Isotope Beam Factory (RIBF). The lifetime problem of carbon-foil strippers due to the high energy loss of beams was a principal bottleneck for the intensity upgrade. We have already developed and successfully operated a re-circulating He-gas stripper for 10-MeV/u uranium beams as an alternative to carbon foils. Recently, the 2nd gas stripper with air dedicated for 50-MeV/u ¹²⁴Xe beams was developed. The differential pumping techniques similar to that used in the He gas stripper was applied. We confined a very thick gas target, up to 20~mg/cm² of air, in a 0.5-m target chamber. One good feature of using air is that it can be inexhaustible for our use. The stripper was stably operated in user runs performed in June 2013. The service rate reached 91\%. The maximum beam intensity reached 38~pnA and the average intensity provided to users becomes approximately four times higher than it was in 2012. The down-time free gas strippers greatly contributed to these improvements. We also discuss the applicability of the air stripper to 50-MeV/u ²³⁸U beams.

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THPRI013

A Beam Driven Plasma-wakefield Linear Collider from Higgs Factory to Multi-TeV

plasma, electron, positron, linear-collider

3791

J.-P. Delahaye, E. Adli, S.J. Gessner, M.J. Hogan, T.O. Raubenheimer
SLAC, Menlo Park, California, USA
W. An, C. Joshi, W.B. Mori
UCLA, Los Angeles, California, USA

An updated design of a beam-driven Plasma Wake-Field Acceleration Linear Collider (PWFA-LC) covering a wide range of beam collision energy from Higgs factory to multi-TeV is presented. The large effective accelerating field on the order of 1 GV/m and high wall-plug to beam power transfer efficiency of the beam driven plasma technology in a continuous operation mode allows to extend linear colliders to unprecedented beam collision energies up to 10 TeV with reasonable facility extension and power consumption. An attractive scheme of an ILC energy upgrade using the PWFA technology in a pulsed mode is discussed. The major critical issues and the R&D to address their feasibility in dedicated test facilities like FACET and FACET2 are outlined, especially the beam quality preservation during acceleration and the positron acceleration. Finally, a tentative scenario of a series of staged facilities with increasing complexity starting with short term application at low energy is developed.

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THPRI035

Design and Simulation of Side Coupled Six MeV Linac for X-Ray Cargo Inspection

cavity, coupling, simulation, electron

3844

S. Ahmadiannamin, F. AbbasiDavani, R. Ghaderi, F. Ghasemi
sbu, Tehran, Iran
M. Lamehi Rashti
IPM, Tehran, Iran
S. Zarei
Nuclear Science and Technology Research, InstituteRadiation Application School, Tehran, Iran

Using in X-ray cargo inspection is one of most applications of linear accelerators. This paper represents design and simulation of Side Coupled Six MeV cavity. The electromagnetic simulation of structure was carried out in the SUPERFISH and CST Microwave studio. 2.3 MW input power is considered according to MG5193 magnetron. The coupling coefficient is calculated equal to 3% for stabilization of accelerator operation against environmental and mechanical errors effects.

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THPRI046

Air-cooled Magnetic Alloy Cavity for J-PARC Doubled Rep.-rate Scenario

cavity, impedance, injection, ion

3869

C. Ohmori, K. Hara, K. Hasegawa, K. Takata, M. Toda, M. Yoshii
KEK, Ibaraki, Japan
M. Nomura, A. Schnase, T. Shimada, F. Tamura, M. Yamamoto
JAEA/J-PARC, Tokai-mura, Japan

The upgrade project of the J-PARC MR (Main Ring) is in progress to deliver the beam power of 750 kW based on doubled repetition-rate scenario. The present RF section will be occupied by 9 sets of new magnetic alloy, FT3L, cavity using the direct water cooling scheme. The direct water cooling requires dedicated high-quality cooling water. These cavities will be used for the fundamental RF for acceleration. The second harmonic RF is necessary to increase the bunch length. This allows to enlarge the beam current, and to relax the space charge effects during the injection. Thanks to the high impedance FT3L, the power loss in the second harmonic RF system becomes moderate. The air cooled cavity is designed to fit in any space in the MR where the dedicated water is not available. This paper reports the design of the second RF system, technical issues to produce the magnetic alloy cores to fit the air cooling, and construction of the system.

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THPRI047

Large-aperture Travelling-wave Accelerator Structure for Positron Capture of SuperKEKB Injector Linac

positron, operation, linac, solenoid

3872

S. Matsumoto, T. Higo, K. Kakihara, T. Kamitani, M. Tanaka
KEK, Ibaraki, Japan

Comparing to the previous KEKB, the four-times higher charge of 4 nC per bunch is required for the injector linac of SuperKEKB. Not only a flux concentrator will be introduced but also the physical aperture of the downstream six 2m-long accelerator structures was increased as large as 30mm in diameter. We call these structures as LAS, “Large Aperture S-band” structure. The resultant higher RF group velocity of about 3% makes the acceleration gradient lower. In the nominal acceleration system, a 40MW klystron with SLED feeds four 2m-long accelerator structures producing 20MV/m acceleration field. The acceleration gradient higher than 14 MV/m is required for the very first two LAS structures to suppress the satellite bunches. This gradient is obtained by feeding only two LAS structures. Initially, ten LAS structures were installed and the RF processing has partly started. In the present paper, we firstly describe the acceleration system design and then present the processing characteristics through the RF processing without beam and with beam.

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THPRI052

Design, Fabrication and Tests of the Second Prototype of the Double-Length CLIC PETS

vacuum, alignment, collider, RF-structure

3887

L. Sánchez, J. Calero, D. Gavela, J.L. Gutiérrez, F. Toral
CIEMAT, Madrid, Spain
D. Gudkov, G. Riddone
CERN, Geneva, Switzerland

Funding: This work has been partially funded by the Spanish Ministry of Economy and Competitiveness under project FPA2010-21456-C02-02
The future collider CLIC is based on a two-beam acceleration scheme, where the drive beam provides to the main beam the RF power through the Power Extraction and Transfer Structures (PETS). The technical feasibility of some components is currently being proved at the CLIC Experimental Area (CLEX). Two double- length CLIC PETS will be installed in CLEX to validate their performance with beam. The first prototype was produced and validated in 2012. This paper is focused on the engineering design, fabrication and validation of the second prototype. Taking into account the results of the first prototype, some modifications have been included in the design to ease fabrication and assembly. The fabrication techniques are very similar to the ones used for the first prototype. Mechanical measurements on single parts and different assembly stages will be reported. The industrialization feasibility will be also analyzed. Finally, several tests such as vacuum tightness and RF measurements with low power have been realized to validate the device. These results are compared with the first prototype ones.

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THPRI080

The New Design for Capture Cavity of CEBAF

cavity, coupling, electron, simulation

3955

S. Wang, J. Guo, R.A. Rimmer, H. Wang
JLab, Newport News, Virginia, USA

In CEBAF, the electron beam from the injector must be sufficiently relativistic to match a 1 GeV recirculated beam in the first linac. The electron beam is produced with a ~130 keV electron gun, then accelerated by a room temperature, graded-beta standing wave linac, capture section, from 130 keV to 510 keV before enters two 5-cell superconducting RF cavities for further acceleration. Present capture cavity is a 5-cell side-coupled cavity. We designed a new slot-coupled cavity which has lower power consumption and simpler structure.

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FRYBA01

Long-term Accelerator R&D as an Independent Research Field

laser, electron, plasma, SRF

4073

R. Brinkmann
DESY, Hamburg, Germany

High energy physics projects have been important drivers of accelerator R&D for several decades. The resulting accelerator technology was used to construct frontier accelerators for HEP but was also very successfully applied in accelerators for other science fields, in particular photon science, nuclear physics, medical applications, … Fewer HEP projects and at the same time a growing number of projects in other areas require a modified approach to accelerator R&D. Efforts and progress to perform accelerator R&D as an independent research program with its own, independent funding are described for the example of the Helmholtz ARD program in Germany. Links to efforts in other countries are discussed and an outlook to future accelerator research is given.

Slides FRYBA01 [3.581 MB]

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