Keyword: wakefield
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MOYBB101 Review of Laser Wakefield Accelerators electron, laser, plasma, injection 11
 
  • V. Malka
    LOA, Palaiseau, France
  
  Funding: European Research Council for funding the PARIS ERC project (Contract No. 226424). EC FP7 LASERLABEUROPE/ LAPTECH (Contract No. 228334) EuCARD/ANAC, EC FP7 (Contract No. 227579)
This review talk will highlight the tremendous evolution of the research on laser wakefield accelerators* that has, in record time, led to the production of high quality electron beams beyond the GeV level, using compact laser systems. I will describe the path we followed to explore different injection schemes (bubble, colliding laser pulses, injection in gradient, longitudinal and transverse, ionisation injection) and I will present the most significant breakthroughs which allowed to generate stable, high peak current and high quality electron beams, with control of the charge, of the relative energy spread and of the electron energy. Modelling and experimental results will be as well reported with examples of applications**.
* V. Malka, Physics of Plasmas 19, 055501 (2012)
** V. Malka et al., Nature Physics 4, 447 (2008)
 		 
slides icon Slides MOYBB101 [14.550 MB]  
 
MOPEA019 Studies of Bunch-bunch Interactions in the ANKA Storage Ring with Coherent Synchrotron Radiation using an Ultra-fast Terahertz Detection System radiation, synchrotron, storage-ring, synchrotron-radiation 109
 
  • A.-S. Müller, B.M. Balzer, C.M. Caselle, N. Hiller, M. Hofherr, K.S. Ilin, V. Judin, B. Kehrer, S. Marsching, S. Naknaimueang, M.J. Nasse, J. Raasch, A. Scheuring, M. Schuh, M. Schwarz, M. Siegel, N.J. Smale, J.L. Steinmann, P. Thoma, M. Weber, S. Wuensch
    KIT, Karlsruhe, Germany
  
  Funding: Supported by Initiative and Networking Fund of the Helmholtz Association under contract No. VH-NG-320 and German Federal Ministry of Education and Research under Grant. Noss. 05K10VKC and 05K2010VKD
In the low-alpha operation mode of the ANKA synchrotron light source, coherent synchrotron radiation (CSR) is emitted from short electron bunches. Depending on the bunch current, the radiation shows bursts of high intensity. These bursts of high intensity THz radiation display a time evolution which can be observed only on long time scales with respect to the revolution period. In addition, long range wake fields can introduce a correlation between the bunches within a bunch train and thus modify the observed behavior. A novel detection system consisting of an ultra-fast superconducting THz detector and data acquisition system was used to investigate correlations visible on the bursting pattern and to study the interactions of very short pulses in the ANKA storage ring. 		 
 
MOPFI076 Electron Emission Studies in the New High-charge Cs2Te Photoinjector at Argonne National Laboratory gun, cathode, laser, factory 455
 
  • E.E. Wisniewski, M.E. Conde, W. Gai, C.-J. Jing, W. Liu, J.G. Power
    ANL, Argonne, USA
  • L.K. Spentzouris, Z.M. Yusof
    Illinois Institute of Technology, Chicago, Illinois, USA
  
  Funding: This work was funded by the U.S. Dept. of Energy Office of Science under contract number DE-AC02-06CH11357.
A new L-band 1.3 GHz 1.5 cell gun for the new 75 MeV drive beam is being commissioned and will soon be operating at the Argonne Wakefield Accelerator (AWA) facility as part of the facility upgrade (see M. E. Conde, this proceedings.) The photoinjector is high-field (peak accelerating field > 80MV/m) and has a large \mathrm{Cs}2\mathrm{Te} photocathode (diameter > 30 mm) fabricated in-house. The photoinjector generates high-charge, short pulse, single bunches (Q > 100 nC) or bunch-trains (Q ≈ 1000 nC) for wakefield experiments. Field emission from the \mathrm{Cs}2\mathrm{Te} cathode is to be measured during RF conditioning and benchmarked against measurements from a copper cathode. Quantum efficiency (QE) will be measured in single and multi-bunch modes. Preliminary results are presented. 		 
 
MOPME014 Electro-optical Bunch Length Measurements at the ANKA Storage Ring laser, electron, storage-ring, background 500
 
  • N. Hiller, A. Borysenko, E. Hertle, E. Huttel, V. Judin, B. Kehrer, S. Marsching, A.-S. Müller, M.J. Nasse, A. Plech, M. Schuh, S.N. Smale
    KIT, Karlsruhe, Germany
  • P. Peier, V. Schlott
    PSI, Villigen PSI, Switzerland
  • B. Steffen
    DESY, Hamburg, Germany
  
  Funding: Supported by the Initiative and Networking Fund of the Helmholtz Association under contract number VH-NG-320 and by the German Federal Ministry of Education and Research under contract number 05K10VKC
A setup for near-field electro-optical bunch length measurements has recently been installed into the UHV system of the ANKA storage ring. For electro-optical bunch length measurements during ANKA's low alpha operation, a laser pulse is used to probe the field induced birefringence in an electro-optical crystal (GaP in our case). The setup allows for both electro-optical sampling (EOS, multi-shot) and spectral decoding (EOSD, single- and multi-shot) measurements. This paper presents first results and discusses challenges of this method employed for the first time at a storage ring. 		 
 
MOPME015 Numerical Wakefield Calculations for Electro-optical Measurements simulation, laser, storage-ring, impedance 503
 
  • B. Kehrer, A. Borysenko, E. Hertle, N. Hiller, V. Judin, S. Marsching, A.-S. Müller, M.J. Nasse, M. Schuh
    KIT, Karlsruhe, Germany
  
  Funding: This project is funded by the Federal Ministry of Education and Research under the contract number 05K10VKC
The technique of electro-optical measurements allows precise and single-shot measurements of the bunch length and shape. The installation of such a near-field setup changes the impedance of the storage ring and the corresponding effects have to be studied carefully. One possibility is to use numerical codes for simulating the wakefields induced by the setup. Such simulations has been done using the wakefield solver implemented in the CST Studio Suite. In this paper we present the simulation results together with first measurements. 		 
 
MOPME018 BEAM OSCILLATION MONITOR FOR THE MULTI-BUNCH BEAM kicker, damping, linac, extraction 506
 
  • T. Naito, S. Araki, H. Hayano, K. Kubo, S. Kuroda, T. Okugi, N. Terunuma, J. Urakawa
    KEK, Ibaraki, Japan
  
  In order to observe the motion of bunch-by-bunch beam oscillation of multi-bunch in the storage ring, we developed two measurement tools. One is a signal process electronics circuit using fast analogue switches. The circuit picks up one of the selected bunch signal of the beam position monitor from the multi-bunch. The selected beam position signal can be processed as a single bunch beam. By changing the gate timing, arbitrary bunch signal can be selected. The other is a waveform memory using a high bandwidth oscilloscope. The long waveform memory of the oscilloscope has a capability to acquire the multi-turn waveform of the button electrode signals. The beam test of the circuit has been carried out at KEK-ATF damping ring in the cases of 2.8ns bunch spacing and 5.6ns bunch spacing, respectively. The detail of the hardware and the result of the beam test are reported.  
 
MOPWA052 Short Range Wakefield Measurements of High Resolution RF Cavity Beam Position Monitors at ATF2 cavity, quadrupole, simulation, extraction 792
 
  • J. Snuverink, S.T. Boogert, F.J. Cullinan, Y.I. Kim, A. Lyapin
    JAI, Egham, Surrey, United Kingdom
  • K. Kubo, T. Okugi, T. Tauchi, N. Terunuma, J. Urakawa
    KEK, Ibaraki, Japan
  • G.R. White
    SLAC, Menlo Park, California, USA
  
  Cavity beam position monitors (CBPM) have been used in several accelerator facilities and are planned to be used in future accelerators and light sources. High position resolution up to tens of nanometres has been achieved, but short range wakefields are a concern, especially for small beam emittances. This paper presents the wakefield calculations as well as the first measurements of the CBPM-generated short range wakefields performed at the Accelerator Test Facility (ATF2).  
 
MOPWA055 Status of Higher Order Mode Beam Position Monitors in 3.9 GHz Superconducting Accelerating Cavities at FLASH HOM, cavity, dipole, diagnostics 798
 
  • P. Zhang, R.M. Jones, I.R.R. Shinton
    UMAN, Manchester, United Kingdom
  • N. Baboi, P. Zhang
    DESY, Hamburg, Germany
  • T. Flisgen, U. van Rienen
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
  
  Funding: This work was partially funded by the European Commission under the FP7 Research Infrastructures grant agreement No.227579.
Higher order mode (HOM) beam position monitors (BPM) are being developed for the 3.9GHz third harmonic superconducting accelerating cavities at FLASH. The transverse beam position in a cavity can be determined utilizing beam-excited HOMs based on dipole components. The existing couplers used for HOM suppression provide the necessary signals. The diagnostics principle is similar to a cavity BPM, but requires no additional vacuum instruments on the linac. The challenges lie in the dense HOM spectrum arising from couplings of the majority HOMs amongst the four cavities in the cryo-module. HOMs with particularly promising diagnostics features were evaluated using various devices with various analysis methods. After careful theoretical and experimental assessment of HOMs, multi-cavity modes at ~5GHz were chosen to provide a global position over the complete module with superior resolution (~20μm) while trapped modes at ~9GHz provide local position in each cavity with comparable resolution (~50μm). A similar HOM-BPM system is planned for the European XFEL 3.9GHz module with 8 cavities. This paper reviews both the current status and the future prospects of HOM-BPMs in 3.9GHz cavities. 		 
 
MOPWO004 Simulations and Studies of Electron Beam Dynamics under Compton Back-scattering for the Compact X-ray Source ThomX electron, simulation, collective-effects, photon 888
 
  • I.V. Drebot, C. Bruni, N. Delerue, T. Demma, A. Variola, Z.F. Zomer
    LAL, Orsay, France
  • A. Loulergue
    SOLEIL, Gif-sur-Yvette, France
  
  Funding: This work is supported by the French "Agence Nationale de la Recherche" under reference ANR-10-EQPX-51, and also by grants from Région Ile-de-France, Université Paris-Sud and IN2P3/CNRS.
In this article are presented beam dynamics investiga- tions of a relativistic electron bunch in the compact storage ring ThomX (50 MeV), which is under construction at LAL to produce hard X-ray using Compton Back-Scattering (CBS). The effect of CBS has been implemented in a 6D tracking code. In addition to CBS, the influence of lattice non linearities and various collective effects on the flux of scattered Compton photons is investigated. 		 
 
MOPWO023 Upgrade and Systematic Measurement Campaign of the ATF2 Multi-OTR System target, emittance, coupling, extraction 933
 
  • A. Faus-Golfe, J. Alabau-Gonzalvo, C. Blanch Gutierrez, J. Resta-López
    IFIC, Valencia, Spain
  • J. Cruz, E. Marín, D.J. McCormick, G.R. White, M. Woodley
    SLAC, Menlo Park, California, USA
  
  A multi-Optical Transition Radiation (mOTR) system made of four stations is being used routinely since September 2011 for transverse beam size measurement and emittance reconstruction in the extraction line of ATF2, providing diagnostic support during the ATF2 tuning operation. Furthermore it is also an excellent tool for fast transverse coupling correction. Due to the compactness of the current design the system has an influence in the increase of the transverse emittance due to wakefield effects when a simultaneous measurement is made. To avoid this effect a new target holder and a new optics has been designed and implemented. In this paper we describe the present status of the ATF2 mOTR system, showing recent performance results, and hardware design improvements.  
 
MOPWO024 Design of the CLIC Pre-Main Linac Collimation System collimation, emittance, linac, damping 936
 
  • R. Apsimon, A. Latina, D. Schulte, J.A. Uythoven
    CERN, Geneva, Switzerland
  • J. Resta-López
    IFIC, Valencia, Spain
  
  A main beam collimation system, upstream of the main linac, is essential to protect the linac from particles in the beam halo. The proposed system consists of an energy collimation (EC) system just after the booster linac near the start of the Ring-to-Main Linac (RTML) transfer line and an EC and betatron collimation (BC) system at the end of the RTML, just before the main linac. The design requirements are presented and the cleaning efficiency of the proposed systems is analysed for different design choices.  
 
MOPWO053 Evolution of the Tracking Code PLACET simulation, linac, cavity, collider 1014
 
  • A. Latina, Y.I. Levinsen, D. Schulte
    CERN, Geneva, Switzerland
  • J. Snuverink
    JAI, Egham, Surrey, United Kingdom
  
  The tracking code PLACET simulates beam transport and orbit corrections in linear accelerators. It incorporates single- and multi-bunch effects, static and dynamic imperfections. A major restructuring of its core has resulted in an improvement in its modularity, with some immediate advantages: its tracking core, which is one of the fastest available for this kind of simulations, is now interfaced toward three different scripting languages to offer great simulation capabilities: Tcl/Tk, Octave and Python. These three languages provide access to a vast library of scientific tools, mechanisms for parallel computing, and access to Java interfaces for control systems (such as that of CTF3). Also, new functionalities have been added: parallel tracking to exploit modern multicore CPUs, the possibility to track through the interaction region in presence of external magnetic fields (detector solenoid) and higher order imperfections in magnets. PLACET is currently used to simulate the CLIC Drive Beam, the CLIC Main Beam, CTF3, FACET at SLAC, and ATF2 at KEK.  
 
MOPWO070 Higher Order Symplectic Integration of Collective Effects collective-effects, simulation, space-charge, beam-transport 1046
 
  • S.D. Webb, D.T. Abell
    Tech-X, Boulder, Colorado, USA
  
  Long time tracking simulations of intense beams requires a proper account for the collective effects. Many tracking codes allow the number of space charge kicks, for example, to be determined by the end user. This makes no guarantee that the integration is second order accurate in the step size. In this proceeding, we present results on the proper second- and fourth-order symplectic integration of the Hamiltonian dynamics of particles under collective interactions using a model Hamiltonian with collective space charge forces to illustrate the underlying principles.  
 
TUOCB101 Argonne Wakefield Accelerator (AWA): A Facility for the Development of High Gradient Accelerating Structures and Wakefield Measurements electron, acceleration, linac, gun 1111
 
  • M.E. Conde, S.P. Antipov, D.S. Doran, W. Gai, C.-J. Jing, R. Konecny, W. Liu, J.G. Power, E.E. Wisniewski, Z.M. Yusof
    ANL, Argonne, USA
  • S.P. Antipov, C.-J. Jing, R. Konecny
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • E.E. Wisniewski, Z.M. Yusof
    Illinois Institute of Technology, Chicago, Illinois, USA
  
  Funding: Work supported by the U.S. Department of Energy under contract No. DE-AC02-06CH11357.
The recently upgraded AWA facility is being commissioned. Operation of the new L-Band RF gun with a Cesium Telluride photocathode will generate long electron bunch trains, with high charge per bunch (up to 100 nC). The six new linac tanks will boost the beam energy to 75 MeV, making it an extremely well suited drive beam to excite wakefields in structures. One of the main goals of the facility is to generate RF pulses with GW power levels, corresponding to accelerating gradients of hundreds of MV/m and energy gains on the order of 100 MeV per structure. A key aspect of the studies and experiments carried out at the AWA facility is the use of relatively short RF pulses (15 – 25 ns), which is believed to mitigate the risk of breakdown and structure damage. 		 
slides icon Slides TUOCB101 [3.416 MB]  
 
TUPEA008 Physics of the AWAKE Project plasma, electron, laser, injection 1179
 
  • P. Muggli, E. Oz, R. Tarkeshian
    MPI, Muenchen, Germany
  • C. Bracco, E. Gschwendtner, A. Pardons
    CERN, Geneva, Switzerland
  • A. Caldwell, O. Reimann
    MPI-P, München, Germany
  • K.V. Lotov
    BINP SB RAS, Novosibirsk, Russia
  • A.M. Pukhov
    HHUD, Dusseldorf, Germany
  • J. Vieira
    IPFN, Lisbon, Portugal
  • M. Wing
    UCL, London, United Kingdom
  
  The goal of the AWKAKE collaboration is the study of plasma wakefields driven by proton (p+) bunches through experiments, simulations and theory. Proton bunches are interesting wakefield drivers because they can be ultra-relativistic (TeVs/p+) and carry large amounts of energy (>kJ). It was demonstrated in simulations* that acceleration of an electron (e-) bunch from 10GeV to >500GeV can be achieved in ~500m of plasma driven by a 1TeV, 100micron-long, bunch with 1011 p+. Such short p+ bunches do not exist today. It was suggested** that a p+ bunch long compared to the plasma period can transversely self-modulate and resonantly drive wakefields to large amplitudes (~GV/m). Initial experiments based on self-modulation instability (SMI) will use single 12cm-long CERN SPS bunches with 1-3·1011, 450GeV p+ to study physics of SMI. With a plasma density of 7·1014/cc the plasma wave and modulation period is 1.3mm. The SMI saturates after ~3m with amplitude in the GV/m range. Later a low energy (~10MeV) witness e- bunch will be injected at the SMI saturation point. Energy gain over ~7m of plasma can reach the GeV level. Translation from physics to experimental plan and setup will be presented.
* A. Caldwell et al., Nature Physics 5, 363 (2009)
** N. Kumar et al., Phys. Rev. Lett. 104, 255003 (2010) 		 
 
TUPEA021 Calculation of Wakefields in Plasma Filled Dielectric Capillaries Generated by a Relativistic Electron Beam plasma, electron, positron, collider 1205
 
  • C. Li, W. Gai
    ANL, Argonne, USA
  • C. Li, C.-X. Tang, H. Zha
    TUB, Beijing, People's Republic of China
  
  In this paper we give an analytical solution of TM0n mode for wakefields generated by a relativistic electron beam passing through plasma-filled capillary waveguides. The numerical solution shows that the fields of TM0n modes could not be ignored when the plasma wave length is comparable with the effective radius of the capillary tube, which means that the boundaries are not shielded completely by plasma. Numerical examples are given in several typical cases.  
 
TUPEA029 Theory Calculation of PASER in Gas Mixture Active Medium electron, resonance, laser, plasma 1211
 
  • X.F. Tian, C.-F. Wu
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  
  In the PASER (particle acceleration by stimulated emission of radiation), the energy stored in an active medium transferred directly to the electron beam passing through in discrete amounts by emitting a photon when the bounded electron returns from upper to lower energy state. In this paper, the wake-field generated by a bunch of electrons traversing in an active medium has been discussed. The calculations of the development of amplitude for gas mixture active medium about CO2 and ArF were made respectively. The results show that the gradient can reach around 1GeV/m. In addition, the electron energy gain occurring as a train of electron micro-bunches traversing in gas mixture was analyzed by a two dimension model. The train of micro-bunches can obviously gain energy from the active medium and the energy exchange is linearly proportional to the interaction length d. The influence of the bunch figure and other quantities on the energy exchange occurring as a train of electron micro-bunches traversing CO2 gas mixture were investigated when the interaction length is 0.5m. The results illustrate that maximum electron energy gain can be obtained by the train of micro-bunches with optimized parameters.  
 
TUPEA045 Self-Modulation and Hosing Instability of Slac Electron and Positron Bunches in Plasmas electron, plasma, positron, simulation 1235
 
  • J. Vieira, N.C. Lopes
    Instituto Superior Tecnico, Lisbon, Portugal
  • E. Adli, S.J. Gessner, M.J. Hogan, S.Z. Li, M.D. Litos
    SLAC, Menlo Park, California, USA
  • Y. Fang
    USC, Los Angeles, California, USA
  • C. Joshi, K.A. Marsh, W.B. Mori, N. Vafaei-Najafabadi
    UCLA, Los Angeles, California, USA
  • P. Muggli
    MPI, Muenchen, Germany
  • O. Reimann
    MPI-P, München, Germany
  • L.O. Silva
    IPFN, Lisbon, Portugal
  
  Funding: This work has been partially supported by Humboldt Foundation.
The understanding of the self-modulation (SMI) and hosing (HI) instabilities is critical for the success of the upcoming proton driven plasma wakefield acceleration experiments at CERN*. The use of long SLAC electron and positron bunches provides the possibility of understanding experimentally the interplay between SMI and HI. In this work we perform particle-in-cell simulations with the code OSIRIS with parameters that will be available for experiments at SLAC in 2013. We show that the SMI of 20 GeV lepton bunches can grow and saturate in less than 15 cm. Up to 8 GeV energy gain/loss could be observed after a meter long plasma. The HI can also be effectively mitigated by seeding the SMI using bunches with short rise times**. We also show analytically and numerically that in the linear regime and after saturation of the SMI the HI can be suppressed by a plasma-BNS damping analogue. Several diagnostics that could be used in experiments to measure the SMI development and these effects are also explored.
*G. Xia et al., J. Plasma Phys., 1-7 (2012).
**J. Vieira et al., Phys. Plasmas 19, 063105 (2012). 		 
 
TUPEA048 Simulation of Self-modulating Particle Beams in Plasma Wakefield Accelerators plasma, simulation, proton, electron 1238
 
  • K.V. Lotov
    BINP SB RAS, Novosibirsk, Russia
  • K.V. Lotov, A. Sosedkin
    NSU, Novosibirsk, Russia
  • E. Mesyats
    ICM&MG SB RAS, Novosibirsk, Russia
  
  Funding: The Ministry of education and science of Russia, project 14.B37.21.0784.
Controlled self-modulation of long proton or electron beams is a new trend in plasma wakefield acceleration which sets a new goal for simulation codes. Long interaction lengths (tens of meters), long beams (up to hundred of plasma wave periods), motion of plasma ions, and violation of fluid approximation are factors that makes the problem too heavy for general purpose codes. Only specialized codes can attack this problem in real geometry. We describe recent upgrades of the code LCODE which enabled simulations of long dense proton beams and report results of numerical studies of proton beam-plasma interaction in the context of AWAKE project. 		 
 
TUPEA049 Wakefields of Ultrarelativistic Bunches in Cold Magnetized Plasma plasma, radiation, electron, acceleration 1241
 
  • S.N. Galyamin, A.V. Tyukhtin
    Saint-Petersburg State University, Russia
  
  Funding: Work is supported by Russian Foundation for Basic Research and the Dmitry Zimin "Dynasty" Foundation.
We deal with electromagnetic field of various bunches moving in a cold magnetized plasma along the external magnetic field. The main attention is paid to the case of ultrarelativistic motion. First, for the case of point charge, we obtain the approximate formulas which are valid in the far-field zone and in the vicinity of the charge trajectory. These expressions predict the beating behavior of the far field and the harmonic behavior of the near field. Moreover, the magnitude of the longitudinal components of both electric and magnetic field as well as the transversal electric field possess singularity on the charge trajectory. Second, using formulas for the point charge field as Green function, we develop an effective algorithm for calculation of the bunch wakefield. Plots of wakefields produced by typical bunches are given. Prospects of using the bunch field properties for further development of the plasma wakefield acceleration technique are discussed. 		 
 
TUPEA053 Feasibility Study of the AWAKE Facility at CERN proton, plasma, electron, laser 1253
 
  • E. Gschwendtner, C. Bracco, B. Goddard, M. Meddahi, A. Pardons, E.N. Shaposhnikova, H. Timko, F.M. Velotti, H. Vincke
    CERN, Geneva, Switzerland
  
  Plasma Wakefield acceleration is a rapidly developing field which appears to be a promising candidate technology for future high-energy accelerators. The Proton Driven Plasma Wakefield Acceleration has been proposed as an approach to eventually accelerate an electron beam to the TeV energy range in a single plasma section. To verify this novel technique, a proof-of-principle demonstration experiment, AWAKE, is proposed using 400 GeV proton bunches from the SPS. Detailed studies on the identification of the best site for the installation of the AWAKE facility resulted in proposing the CNGS facility as best location. Design and integration layouts covering the beam line, the experimental area and all interfaces and services will be shown. Among other issues, radiation protection, safety and civil engineering constraints will be raised.  
 
TUPEA055 Quasistatic Field Influence on Bunches Focusing by Wakefields in the Plasma-dielectric Waveguide plasma, focusing, electron, acceleration 1256
 
  • R.R. Kniaziev
    KhNU, Kharkov, Ukraine
  • G.V. Sotnikov
    NSC/KIPT, Kharkov, Ukraine
  
  Funding: The research is supported in part by Global Initiatives for Proliferation Prevention (GIPP) program, project ANL-T2-247-UA (STCU Agreement P522).
Acceleration of charged particles by wakefields, excited by a drive electron bunch in the dielectric waveguide, is a perspective method in accelerator physics. We have previously proposed using plasma, filling the drift channel of the dielectric structure (DS), for focusing of the accelerated bunch*. The analytical expressions, obtained for the components of the electromagnetic field, considered only the propagating wake field, and did not consider quasi-static fields of electron bunches that are important for calculating bunches dynamics. In this paper we report the result of numerical calculations of the influence of quasistatic field of bunches on focusing by wake fields in the plasma-dielectric accelerator. We refine analytical expressions for the electromagnetic field by adding components of bunch quasi-static fields and show the correlation of total force and their quasi-static components.
* R.R. Knyazev, G.V. Sotnikov. Focusing of accelerated particles by wakefields of a drive bunch in a plasma-dielectric waveguide. Proc. of IPAC2012, New Orleans, Louisiana, USA, paper weppp003.pdf 		 
 
TUPEA056 Concept of Dielectric Wakefield Accelerator Driven by a Long Sequence of Electron Bunches electron, acceleration, injection, resonance 1259
 
  • I.N. Onishchenko, V. Kiselev, A. Linnik, G.V. Sotnikov
    NSC/KIPT, Kharkov, Ukraine
  
  Funding: This study is supported by Global Initiatives for Proliferation Prevention (GIPP) program, project ANL-T2-247-UA (STCU Agreement P522)
The scheme of a two-beam accelerator type is considered that is based on wakefield excitation in rectangular dielectric resonator by a sequence of electron bunches with the aim to enhance wakefield intensity due to multi-bunch coherent excitation, multi-mode summation, and wakefield accumulation in resonator. The sequence of bunches can be divided into exciting and accelerated parts in any proportion by means at the proper detuning of bunch repetition frequency relative to the frequency of principle eigen mode of the resonator. A train of 6000 electron bunches, each of energy 4.5МeV, charge 0.16nC, duration 60psec, diameter 1.0cm, and angular spread 0.05 mrad is produced with the linear resonant accelerator. Bunch repetition frequency is 2805 MHz and can be varied within 2MHz by changing master oscillator frequency. Bunches are injected into copper rectangular waveguide of cross-section 8.5x18.0cm2 and length 75cm along wide sides of which Teflon plates are placed. The plate thickness is chosen 1.67cm so that the frequency of excited eigen mode coincides with bunch repetition frequency. 		 
 
TUPEA057 Optimization of Rectangular Dielectric Structures for the Planned Wakefield Acceleration Experiments in KIPT electron, accelerating-gradient, acceleration, vacuum 1262
 
  • G.V. Sotnikov, K.V. Galaydych, V. Kiselev, P.I. Markov, I.N. Onishchenko
    NSC/KIPT, Kharkov, Ukraine
  
  Funding: This study is supported by Global Initiatives for Proliferation Prevention (GIPP) program, project ANL-T2-247-UA (STCU Agreement P522).
We, at the Kharkov Institute of Physics and Technology, planned experimental test of the basic principles of the multi-bunch multi-mode wakefield accelerator. For this purpose we carried out a series of calculations of wakefield excitation and dynamics of the drive and witness bunches in rectangular structures with a dielectric substrate. For optimization two rectangular vacuum waveguides of R32 (72.14mm x 34.04mm) and R26 (86.36mm x 43.18mm) which were filled with the dielectric covering two any opposite metal walls of a waveguide were chosen. As possible dielectric Alumina, Cordierite, or Teflon were tested. It was supposed that the structure will be energized by sequence of electron bunches (bunch repetition frequency is 2.805 GHz), having energy of 4.5 MeV. As the candidate for operating mode LSM-wave or LSE-wave, with frequency to equal the bunch repetition frequency or its doubled frequency were tested. The gradient of an accelerating field, small transverse deflection (or divergence) of drive and witness bunches were the main criteria of optimization. As a result of optimization we propose some dielectric structures for future wakefield experiments in KIPT. 		 
 
TUPEA064 A Proposed Plasma Accelerator Research Station at CLARA Facility plasma, electron, simulation, acceleration 1280
 
  • G.X. Xia, K. Hanahoe
    UMAN, Manchester, United Kingdom
  • D. Angal-Kalinin, J.A. Clarke, J.K. Jones, P.H. Williams
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • J.D.A. Smith
    TXUK, Warrington, United Kingdom
  
  We propose a Plasma Accelerator Research Station (PARS) based at proposed FEL test facility Compact Linear Accelerator for Research and Applications (CLARA) at Daresbury lab. The idea is to use the relativistic electron beam from CLARA, to investigate some key issues in electron beam transport and in the electron beam driven plasma wakefield acceleration, e.g. the two bunch acceleration for CLARA beam energy doubling, high transformer ratio, long bunch self-modulation and the related beam instabilities. This paper discusses the feasibility studies of electron beam parameters to meet the requirements for beam driven wakefield acceleration and the possible experiments which can be conducted at PARS beam line.  
 
TUPEA068 Wake-field Reduction in Hybrid Photonic Crystal Accelerator Cavities lattice, cavity, dipole, simulation 1289
 
  • D. A. Rehn
    Colorado University at Boulder, Boulder, Colorado, USA
  • C.A. Bauer, J.R. Cary, G.R. Werner
    CIPS, Boulder, Colorado, USA
  • J.R. Cary, C.D. Zhou
    Tech-X, Boulder, Colorado, USA
  
  Funding: This work is supported by the U.S. Dept. of Energy, grant DE-FG02-04ER41317.
Photonic crystals (PhCs) have attractive properties for manipulating electromagnetic radiation. In one application, PhCs are composed of a number of dielectric rods that can be arranged to make an accelerator cavity. These structures trap an accelerating mode and allow higher order modes to propagate out. Previous work showed that PhC structures allow excitation of unwanted transverse wake-fields that can disrupt the beam and limit luminosity levels. This work focuses on optimizing PhC cavities to reduce transverse wake-fields by minimizing the Q-factor of unwanted modes, while keeping the Q-factor of the accelerating mode high. The transverse wake-fields in the new optimized structures are compared with previously optimized structures and the CLIC cavity with HOM damping. 		 
 
TUPEA071 THz Bench Tests of a Slab-symmetric Dielectric Waveguide acceleration, laser, simulation, emittance 1292
 
  • F. Lemery, H. Panuganti, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  • D. Mihalcea, P. Piot
    Fermilab, Batavia, USA
  • P. Stoltz
    Tech-X, Boulder, Colorado, USA
  
  Funding: This work is supported by DTRA contract HDTRA1-10-1-0051 and by the U.S. DOE contracts DE-FG02-08ER41532 and DE-AC02-07CH11359.
Dielectric-lined waveguides (DLW) are becoming more popular for beam driven acceleration applications. An experiment to demonstrate beam-driven acceleration using a slab-symmetric dielectric-lined waveguide driven by a flat beam is in preparation at the Advanced Superconducting Test Accelerator (ASTA) at Fermilab. In this paper we characterize the structure using a THz pulse obtained from optical rectification using an amplified laser pulse. After propagation through the DLW structure, the THz pulse is analyzed using a Michelson interferometer and single-shot electro-optical imaging. Data for various gap size will be presented. 		 
 
TUPEA072 Toward a Dielectric-Wakefield Energy Doubler at the Fermilab's Advanced Superconducting Test Accelerator emittance, acceleration, electron, simulation 1295
 
  • F. Lemery, D. Mihalcea, P. Piot, C.R. Prokop
    Northern Illinois University, DeKalb, Illinois, USA
  • P. Piot, Y.-E. Sun
    Fermilab, Batavia, USA
  • P. Stoltz
    Tech-X, Boulder, Colorado, USA
  
  Funding: This work is supported by DTRA contract HDTRA1-10-1-0051 and by the U.S. DOE contracts DE-FG02-08ER41532 and DE-AC02-07CH11359.
The Advanced Superconducting Test Accelerator (ASTA), presently under construction at Fermilab, will produce high-charge (~<3 nC) electron bunches with energies ranging from 50 to eventually 750 MeV. The facility is based on a superconducting linac capable of producing up to 3000 bunches in 1-ms macropulses repeated at 5 Hz. In this paper we explore the use of a short dielectric-lined-waveguide (DLW) linac to significantly increase the bunch energy. The method consists in (1) using advanced phase space manipulation techniques to shape the beam distribution and enhance the transformer ratio, and (2) optimize the generation and acceleration of a low-charge witness bunches. Start-to-end simulations of the proposed concept are presented. This DLW module could also be used to test some aspects of a recently proposed concept for a multiuser short-wavelength free-electron laser utilizing a series of DLW linacs*.
* C. Jing et al., “A Compact Soft X-ray Free-Electron Laser Facility based on a Dielectric Wakefield Accelerator”, Advanced Photon Source LS Note LS-332, Argonne National Laboratory (2012). 		 
 
TUPEA073 Performances of VORPAL-GPU Slab-symmetric DLW simulation, factory, electron, dumping 1298
 
  • F. Lemery, K. Duffin, N. Karonis, D. Mihalcea, P. Piot, J. Winans
    Northern Illinois University, DeKalb, Illinois, USA
  • P.J. Mullowney, P. Stoltz
    Tech-X, Boulder, Colorado, USA
  • P. Piot
    Fermilab, Batavia, USA
  
  Funding: HDTRA1-10-1-0051, DOE(Grant No will be specified later)
GPU-based computing has gained popularity in recent years due to its growing software support and greater processing capabilities than its CPU counterpart.  GPU computing was recently added in the finite-difference time-domain program VORPAL. In this paper we carry electromagnetic simulations and optimization of a flat beam passing through a slab-symmetric dielectric-lined waveguide (DLW). We use this simulation model to explore the scaling of the GPU version of VORPAL on a new TOP1000-grade hybrid GPU/CPU computer cluster available at Northern Illinois University. 		 
 
TUPEA088 Argonne Flexible Linear Collider collider, linac, linear-collider, klystron 1322
 
  • C.-J. Jing, S.P. Antipov, A. Kanareykin, P. Schoessow
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • M.E. Conde, W. Gai, J.G. Power
    ANL, Argonne, USA
  
  We propose a linear collider based on a short rf pulse (~22ns flat top), high gradient (~120MV/m loaded gradient), high frequency (26GHz) two beam accelerator design. This is a modular design and its unique locally repetitive drive beam structure allows a flexible configuration to meet different needs. Major parameters of a conceptual 250GeV linear collider are presented. This preliminary study shows that an efficient (~5% overall), 4MW beam power collider may be achievable. The concept is extendable to the TeV scale.  
 
TUPFI004 Longitudinal Manipulation to Obtain and Keep the Low Emittance and High Charge Electron Beam for SuperKEKB Injector emittance, laser, alignment, gun 1337
 
  • M. Yoshida, N. Iida, T. Natsui, Y. Ogawa, S. Ohsawa, H. Sugimoto, L. Zang, X. Zhou
    KEK, Ibaraki, Japan
  
  The design strategy of SuperKEKB is based on the.nano-beam scheme. The dynamic aperture decreases due to the very small beta function at the interaction point. Thus the injector upgrade is required to obtain the low emittance and high charge beam corresponding to the short beam life and small injection acceptance. The required beam parameters are 5 nC, 20 mm mrad and 4 nC, 6 mm mrad for the electron and positron respectively. For the electron beam, we installed new photocathode RF-Gun with the focusing electric field and temporal adjusting laser system. Further the projected emittance dilution in the LINAC is an important issue for the low emittance injection. The longitudinal bunch length and shape is an important key to avoid the space charge effect and emittance dilution. The longitudinal manipulation using the temporal adjusting laser system and the bunch compression will be presented. Further the longitudinal bunch measurement will be also presented.  
 
TUPME017 Validation of the Microwave Instability in the Damping Ring of SuperKEKB using VFP Solver impedance, damping, simulation, synchrotron 1604
 
  • L. Wang
    SLAC, Menlo Park, California, USA
  • H. Ikeda, K. Ohmi, K. Oide, D. Zhou
    KEK, Ibaraki, Japan
  
  Microwave instability driven by CSR impedance in the damping ring of Super-KEKB is a concern due to its high bunch current. To understand the beam dynamics, we simulate the microwave instability using Vlasov-Fokker-Planck (VFP) solver. The longitudinal wake potential is calculated as a sum of the contributions due to vacuum chamber components distributed around the ring, including geometry wake field and CSR wake. To improve the accuracy of the simulation of microwave instability, the coherent synchrotron radiation impedance is calculated to very high frequency to get more accurate wake field with a short bunch. The CSR wake is much larger than the geometry wake. The threshold is just above the design current and saw-tooth type of instability is found above the threshold.  
 
TUPME022 Study on the Single Bunch Transverse Emittance Growth in BAPS emittance, lattice, vacuum, wiggler 1619
 
  • J. Gao, D. Wang
    IHEP, Beijing, People's Republic of China
  
  Funding: Supported by the National Foundation of Natural Sciences Contract 11175192.
Beijing Advanced photon Source (BAPS) is a proposed next synchrotron radiation facility which has much smaller transverse emittance after SSRF in China, with 5 GeV energy and 1.5 km circumference. In order to explore how small the transverse emittance we can get on BAPS, this paper studies the single bunch transverse emittance growth due to short range wakefield according to J. Gao’ theory. The mechanism of wakefield induced single bunch emittance is explained first and then the transverse emittance at the design beam current is estimated. Also, the tolerances for the transverse loss factor and the vacuum chamber misalignment (or the closed orbit distortion) are presented. 		 
 
TUPME026 Optimization on RF parameters of a Choke-Mode Structure for the Clic Main LINAC simulation, linac, accelerating-gradient, cavity 1628
 
  • H. Zha, H.B. Chen, J. Shi
    TUB, Beijing, People's Republic of China
  
  Funding: This work was support by the National Natural Science Foundation of China (Grant No. 11135004).
A tapered choke-mode structure for the main linac of Compact Linear Collider (CLIC) had been designed. Wakefield suppression of this structure fits the beam dynamic requirements. But it has a lower RF performance compared to the baseline design of CLIC main linac. A genetic algorithm is used in the procedure to find the optimum solution. A new choke-mode structure with 24 regular cells working on 100MV/m has been design, which fits beam dynamic constraints and has higher RF efficiency and lower surface field. 		 
 
TUPME048 Imperfection Tolerances for On-line Dispersion Free Steering in the Main Linac of CLIC linac, emittance, quadrupole, simulation 1673
 
  • J. Pfingstner, A. Latina, D. Schulte
    CERN, Geneva, Switzerland
  
  Long-term ground motion misaligns the elements of the main linac of CLIC over time. Especially the misaligned quadrupoles create dispersion and hence the beam quality is decreased gradually due to an effect called chromatic dilution. Over longer time periods, orbit feedback systems are not capable to fully recover the beam quality and have to be supplemented by dispersion correction algorithms. In this paper, such and dispersion correction algorithm is presented, which is an extended version of the well-known dispersion free steering algorithm. This extended algorithm can recover the beam quality over long time scaled without stopping the accelerator operation (on-line). Tolerances for different imperfections of the system have been identified and a strong sensitivity to the resolution of the wake field monitors of the main linac accelerating structures has been identified. This problem can be mitigated by using a local excitation scheme as will be shown in this work.  
 
TUPWA005 Study of Collective Beam Instabilities for the MAX IV 3 GeV Ring impedance, simulation, vacuum, damping 1730
 
  • M. Klein, R. Nagaoka
    SOLEIL, Gif-sur-Yvette, France
  • G. Skripka, P.F. Tavares, E.J. Wallén
    MAX-lab, Lund, Sweden
  
  The present paper reports on a systematic simulation study made on the collective beam instability in the MAX IV 3 GeV ring. We study both single and multibunch instabilities in the longitudinal plane. Specifically, we focus on the microwave instabilities which are considered to be particularly dangerous for MAX IV, in view of its small effective radius of aperture (beff < 11 mm), the high intensity (500 mA) and the low emittance (0.24 nm.rad) nature of the circulating beam. Single and multibunch tracking are performed using wake fields that were numerically obtained using GdfidL for the ensemble of the vacuum components. A special effort was made to include dynamically the effect of harmonic cavities that lengthen the bunch and introduce Landau damping, whose details are described in the companion paper *. The study aims to confirm the effectiveness of storing long bunches in the 100 MHz RF system, where tune spreads are further increased by the harmonic cavities, in order to fight against collective instabilities.
* M. Klein and R. Nagaoka "Multibunch Tracking Code Development to Account for Passive Landau Cavities", these proceedings 		 
 
TUPWA008 Computation of Wakefields for an In-vacuum Undulator at PETRA III vacuum, undulator, simulation, impedance 1736
 
  • E. Gjonaj, L. Lünzer, T. Weiland
    TEMF, TU Darmstadt, Darmstadt, Germany
  • R. Wanzenberg
    DESY, Hamburg, Germany
  
  Funding: Work supported by DESY, Hamburg, Germany
At DESY the installation of an in-vacuum undulator at the synchrotron radiation facility PETRA III is under consideration. The moveable magnet array of the undulator is installed inside the vacuum chamber to achieve shorter wavelength synchrotron radiation. A thin metal foil covers the magnet structure to mitigate resistive wall wakefields. Moveable tapered transitions connect the magnet structure and the adjacent vacuum duct to reduce the geometric wakefields. Nevertheless these moveable tapered transitions contribute significantly to the impedance budget of PETRA III. The computer codes MAFIA, CST-Studio and PBCI have been used to calculate the longitudinal and transverse wakefields. The results for the loss and kick parameters are presented and compared to the corresponding parameters for a standard undulator section. 		 
 
TUPWA030 Impedances Calculations of Bellows in HLS II Storage Ring impedance, storage-ring, shielding, coupling 1784
 
  • Q. Zhang, W. Li, L. Wang
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  
  The upgrade project of Hefei Lighe Source storage ring is carrying on.In this project,a new Bellows, in which shielding is provided by sprung fingers which can slide along the beam screen,is installed at the accelerator interaction area In order to reduce this impedance to an acceptable value. The contributions of Bellows to short range wakefields and broadband impedance were calculated numerically by Mafia code .  
 
TUPWA057 Effects of Transient CSR Wakefields on Microbunching in a Bunch Compressor impedance, lattice, radiation, FEL 1832
 
  • C.E. Mitchell, J. Qiang
    LBNL, Berkeley, California, USA
  
  Funding: Supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
The standard analytical model of CSR-induced microbunching in a bunch compressor chicane makes use of a steady-state 1-D model of the longitudinal CSR interaction. This model is numerically generalized to include the effects of transient CSR wakefields due to bend entry and exit, as well as CSR that is generated in upstream bends and propagates across one or more lattice elements before interacting with the beam. The resulting linear integral equation for CSR-induced microbunching is solved numerically for the second bunch compressor of a proposed Next Generation Light Source. 		 
 
TUPWA069 Longitudinal Phase Space Dynamics with Novel Diagnostic Techniques at FACET linac, klystron, damping, radiation 1865
 
  • S.J. Gessner, E. Adli, F.-J. Decker, M.J. Hogan, T.O. Raubenheimer
    SLAC, Menlo Park, California, USA
  • A. Scheinker
    LANL, Los Alamos, New Mexico, USA
  
  Funding: Work supported [optional: in part] by the U.S. Department of Energy under contract number DE-AC02-76SF00515.
FACET produces high energy density electron beams for Plasma Wakefield Acceleration (PWFA) experiments. The high energy density beams are created by chirping the electron beam with accelerating sections and compressing the beam in magnetic chicanes. Precise control of the longitudinal beam profile is needed for the drive-witness bunch PWFA experiments currently underway at FACET. We discuss the simulations, controls, and diagnostics used to achieve FACET's unique longitudinal phase space. 		 
 
TUPWO067 Start-to-end Particle Tracking of the FACET Accelerator emittance, linac, klystron, simulation 2018
 
  • N. Lipkowitz, F.-J. Decker, G.R. White, M. Woodley, G. Yocky
    SLAC, Menlo Park, California, USA
  
  Funding: Work supported by Department of Energy contract DE-AC02-76SF00515.
The Facility for Advanced aCcelerator Experimental Tests (FACET) consists of the first two-thirds of the SLAC two-mile linac followed by a final focus and experimental end station. To date, wakefield-dominated emittance growth and dispersion in the linac, as well as dispersive and chromatic effects in the final focus have precluded regular reliable operation that meets the design parameters for final spot size. In this work, a 6-D particle tracking code (Lucretia) is used to simulate the complete machine, with input parameters taken directly from saved machine configurations. Sensitivities of various tuning parameters to the final spot sizes are compared with measurements taken from the real machine, and a set of tuning protocols is determined to improve regular machine operation. 		 
 
WEPWA062 Status of the UK Superconducting Planar Undulator Project undulator, cryogenics, vacuum, radiation 2259
 
  • J.A. Clarke, B.J.A. Shepherd
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • V. Bayliss, T.W. Bradshaw, S.A. Brown, A.J. Brummitt, G.W. Burton, S.J. Canfer, B. Green, S.R. Watson
    STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
  • S.E. Hughes, E.C. Longhi, J.C. Schouten
    Diamond, Oxfordshire, United Kingdom
  
  The UK is developing a short period, narrow aperture, planar superconducting undulator that is planned to be installed and tested in the 3 GeV Diamond Light Source in 2014. This paper will describe the main parameters of the undulator and the key design choices that have been made. First measurements will be presented of a 19 period test module and also the commissioning of the 2K cryogenic turret.  
 
WEPWA080 Development of a Compact Insertion Device for Coherent Sub-mm Generation radiation, linac, laser, impedance 2295
 
  • A.V. Smirnov, R.B. Agustsson, S. Boucher, T.J. Grandsaert, J.J. Hartzell, M. Ruelas, S. Storms
    RadiaBeam, Santa Monica, USA
  • A. Andrews, B.L. Berls, C.F. Eckman, K. Folkman, A.W. Hunt, Y. Kim, A.E. Knowles-Swingle, C. O'Neill, M. Smith
    IAC, Pocatello, IDAHO, USA
  • P. Buaphad, Y. Kim
    ISU, Pocatello, Idaho, USA
  
  Funding: Department of Energy Contracts DE- SC-FOA-0000760 and DE-FG02-07ER84877
A novel design of resonant Cherenkov wakefield extractor that produced a ~0.9 mm wavelength radiation is presented. The experiment was performed at Idaho Accelerator Center (IAC) using specially upgraded 1.3 GHz 44 MeV linac facility. Specifics of the radiator performance and design are outlined including low-energy beam interaction with non-circular geometry. Some elements of the design may have certain potential for future compact mm-sub-mm-wave sources. 		 
 
WEPWO026 HOM Parameters Simulation and Measurement Result of the IHEP02 Low-loss Cavity HOM, cavity, dipole, damping 2372
 
  • H.J. Zheng, J. Gao, S. Jin, Y. Liu, Z.C. Liu, Z.H. Mi, J.Y. Zhai, T.X. Zhao
    IHEP, Beijing, People's Republic of China
  • H. Yuan
    BIAM, Beijing, People's Republic of China
  
  In cavities , there exists not only the fundamental mode which is used to accelerate the beam but also higher order modes(HOMs). The higher order modes excited by beam can seriously affect beam quality, especially for the higher R/Q mode. This paper reports on recent measurements of higher order modes in the IHEP-2 low-loss SRF cavity. Using different methods, the Qext of the dangerous modes passband are got. This result is compared with TESLA result. R/Q of the first three passbands are also got by CST and compared with the results of TESLA cavity and STFBaseline cavity.  
 
WEPFI032 New Calibration Method for Radial Line Experiment collider, cavity, damping, linear-collider 2774
 
  • X.W. Wu, H.B. Chen, J. Shi, H. Zha
    TUB, Beijing, People's Republic of China
  
  A radial line experiment is proposed to test the SiC load disks of the choke-mode structure. However, the general calibration cannot work out in this situation due to lack of matched load. A new calibration method named multi-offset short calibration is proposed. The principles of the method and the calibration steps involved are presented and the results of actual experimentation are used to validate the method. The results show multi-offset short calibration is a feasible method and that this method can provide a viable calibration scheme for radial line measurements.  
 
WEPFI038 R&D of New C-band Accelerating Structure for SXFEL Facility FEL, cavity, impedance, linac 2785
 
  • W. Fang, Q. Gu, Z.T. Zhao
    SINAP, Shanghai, People's Republic of China
  • L. Chen, X. Sheng
    BVERI, Beijing, People's Republic of China
  • D.C. Tong
    TUB, Beijing, People's Republic of China
  
  C-band high gradient accelerating structure is crucial technology for Shanghai Soft X-ray FEL facility. Based on the prototype, the optimized C-band accelerating structure is proposed, and the experimental model is ready for high power test. In this paper, optimization design and some experiment results are presented, also design, fabrication and cold test of experimental model are introduced.  
 
WEPFI057 Longitudinal Design and RF Stability Requirements for the SwissFEL Facility linac, emittance, booster, undulator 2821
 
  • B. Beutner
    PSI, Villigen PSI, Switzerland
  
  The SwissFEL facility will produce coherent, bright, and short photon pulses covering a wavelength range down to an angstrom, requiring an emittance between 0.18 to 0.43 mm mrad at bunch charges between 10 pC and 200 pC. In nominal operation continuous changes in this range will be offered to the users to allow an individual tradeoff between photon power and pulse length. The facility consists of a S-band RF-gun, booster, and a C-band main linac, which accelerates the beam up to 5.8 GeV. Two compression chicanes will provide a nominal peak current of about 1 to 3 kA depending on the charge. The stability of RF systems is a key design issue for stable compression schemes at reliable user facilies. In this paper different operation modes are presented and discussed in terms of machine stability requirements.  
 
WEPFI090 An X-band Dielectric-based Wakefield Power Extractor simulation, damping, vacuum, impedance 2908
 
  • C.-J. Jing, S.P. Antipov, A. Kanareykin, P. Schoessow
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • M.E. Conde, W. Gai, J.G. Power
    ANL, Argonne, USA
  • V.A. Dolgashev, J.R. Lewandowski, S.G. Tantawi, S.P. Weathersby
    SLAC, Menlo Park, California, USA
  • I. Syratchev
    CERN, Geneva, Switzerland
  
  Funding: US DoE SBIR Phase II project under Contract#DE-SC0004322
An X-band dielectric-based wakefield power extractor is under development to function as a high power rf source primarily for Two Beam Accelerator applications. A low surface electric field to gradient ratio and low fabrication cost are two main advantages of the dielectric-loaded accelerating/decelerating structure. We have designed a 12 GHz dielectric-based power extractor that has similar performance parameters to the CLIC PETS (23 mm beam channel, 240 ns pulse duration, 135 MW output per structure) using the CLIC drive beam. In order to study potential rf breakdown issues, as a first step we built a 11.424 GHz dielectric-based power extractor scaled from the 12 GHz design. A high power rf test will be conducted using the SLAC 11.424 GHz high power rf source in Dec. 2012. Results of the high power testing will be reported. Meanwhile, the 12 GHz fully featured dielectric power extractor is also under construction; construction progress and bench tests will be discussed. 		 
 
WEPME006 Optical Synchronization and Electron Bunch Diagnostic at ELBE laser, electron, pick-up, feedback 2932
 
  • M. Kuntzsch, M. Gensch, U. Lehnert, F. Röser, R. Schurig
    HZDR, Dresden, Germany
  • M. Bousonville, M.K. Czwalinna, H. Schlarb, S. Schulz, S. Vilcins
    DESY, Hamburg, Germany
  
  The continuous wave electron accelerator ELBE is upgraded to generate short and highly charged electron bunches (~200fs duration, up to 1 nC) . In the last years a prototype of an optical synchronization system using a mode locked fiber laser has been build up at ELBE which is now in commissioning phase. The stabilized pulse train can be used for new methods of electron bunch diagnostics like bunch arrival time measurements with the potential of femtosecond resolution. At ELBE a bunch arrival time monitor (BAM) has been designed and tested at the accelerator. The contribution will show the design of the BAM and first measurement results at the ELBE accelerator.  
 
THPFI010 High Energy RF Deflectors for the FERMI@Elettra project electron, linac, FEL, vacuum 3309
 
  • M. Dal Forno, S. Biedron, D. Castronovo, P. Craievich, S. Di Mitri, D. La Civita, G. Penco, M. Petronio, F. Pradal, L. Rumiz, L. Sturari, D. Wang, D. Zangrando
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  • P. Craievich
    PSI, Villigen PSI, Switzerland
  • M. Dal Forno, M. Petronio, R. Vescovo
    University of Trieste, Trieste, Italy
  • N. Faure
    PMB-ALCEN, PEYNIER, France
  
  Measuring and controlling the longitudinal phase space and the time-slice emittance of the electron bunch at 1.2 GeV entering in the undulator beam-lines, is crucial to obtain high FEL performances. In the FERMI@Elettra machine, two RF deflecting cavities have been installed at the end of the linac, in order to stretch the electron bunch horizontally and vertically, respectively. The two cavities are individually powered by the same klystron and a switch system is used to choose the deflection plane. This paper reports the RF measurements carried out during the acceptance test, the RF conditioning including the breakdown rate measurements. Finally, the commissioning with electron beam of the deflecting structure and a comparison of the measured electron bunch length evaluated by using the two deflectors are also reported.