IPAC2012 - List of Keywords (laser)

Paper	Title	Other Keywords	Page
MOOAA01	Performance of the Cornell High-Brightness, High-Power Electron Injector	cathode, gun, emittance, electron	20
	B.M. Dunham, A.C. Bartnik, I.V. Bazarov, L. Cultrera, J. Dobbins, C.M. Gulliford, G.H. Hoffstaetter, R.P.K. Kaplan, V.O. Kostroun, Y. Li, M. Liepe, X. Liu, F. Löhl, P. Quigley, D.H. Rice, E.N. Smith, K.W. Smolenski, M. Tigner, V. Veshcherevich, Z. Zhao CLASSE, Ithaca, New York, USA S.S. Karkare, H. Li, J.M. Maxson Cornell University, Ithaca, New York, USA
	Funding: NSF DMR-0807731 The last year has seen significant progress in demonstrating the feasibility of a high current, high brightness photoinjector as required for the Energy Recovery Linac driven X-ray source at Cornell University. Both low emittances (0.4 mm-mrad rms normalized for 100% of the beam at 20 pC per bunch and 0.15 mm-mrad rms core emittance with 70% of the beam, and twice these values at 80 pC per bunch) and high average currents with a good lifetime well in excess of 1000 Coulombs at 5 MeV, 20 mA have been demonstrated. If these beams can be accelerated to 5 GeV without diluting the phase space, it would already provide a beam brightness higher than any existing storage ring. Operational experience, results, and the outlook for the future will be presented.
	Slides MOOAA01 [1.424 MB]

MOOAA02	Instrumentation and Diagnostics for High Repetition Rate Linac-driven FELs	linac, FEL, emittance, diagnostics	23
	J.M. Byrd, S. De Santis, L.R. Doolittle, D. Filippetto, G. Huang, M. Placidi, A. Ratti LBNL, Berkeley, California, USA
	Funding: Work supported by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. One of the concepts for the next generation of linac-driven FELs is a cw superconducting linac driving an electron beam with MHz repetition rates. The beam is then switched into an array of independently configurable FELs. The demand for high brightness beams and the high rep-rate presents a number of challenges for the instrumentation and diagnostics. The high rep-rate also presents opportunities for increased beam stability because of the ability for much higher sampling rates for beam-based feedbacks. In this paper, we present our plans for instrumentation and diagnostics for such a machine.
	Slides MOOAA02 [1.710 MB]

MOOAA03	Fast Feedback Strategies for Longitudinal Beam Stabilization	feedback, controls, electron, free-electron-laser	26
	S. Pfeiffer, M.K. Bock, H. Schlarb, Ch. Schmidt DESY, Hamburg, Germany W. Jałmużna TUL-DMCS, Łódź, Poland G. Lichtenberg, H. Werner TUHH, Hamburg, Germany
	The key for pump-probe and seeding experiments at Free Electron Lasers such as FLASH is a femtosecond precise regulation of the bunch arrival time and compression. To maintain this beam based requirements, both for a single bunch and within a bunch train, it is necessary to combine field and beam based feedback loops. We present in this paper an advancement of the currently implemented beam based feedback system at FLASH. The principle of beam based modulation of the RF set point can be superimposed by a direct feedback loop with a beam optimized controller. Recent measurements of the achieved bunch arrival time jitter reduction to 20 fs have shown the performance gain by this direct feedback method . The combination of both approaches will be presented and possible advantages are discussed. C. Schmidt et al., “Feedback Strategies for Bunch Arrival Time Stabilization at FLASH Towards 10 fs,” FEL’2011, Shanghai, August 2011, THPA26, http://www. JACoW.org.
	Slides MOOAA03 [0.544 MB]

MOOBA03	Development of a High-power Coherent THz Sources and THz-TDS System on the basis of a Compact Electron Linac	electron, radiation, polarization, linac	37
	M. Kumaki, K. Sakaue, M. Washio RISE, Tokyo, Japan R. Kuroda, H. Toyokawa, K. Yamada AIST, Tsukuba, Ibaraki, Japan
	The high-power terahertz time-domain spectroscopy (THz-TDS) has been developed on the basis of a compact S-band electron linac at AIST, Japan. It is strongly expected for inspection of dangerous materials in the homeland security field. The linac consists of a photocathode rf-gun, two acceleration tubes and a magnetic bunch compressor. The 40 MeV, 1 nC electron bunch is generated and compressed to less than 1 ps. THz radiations are generated in two methods with the ultra-short bunch. One is THz coherent synchrotron radiation (CSR). The other is THz coherent transition radiation (CTR). In the preliminary experiment, it was observed that the focused CTR had the donut profile in a transverse fields due to its initial radial polarization, so that it made Z-polarization. In case of the THz-TDS experiment, CTR was controlled to linearly polarization with the polarizer and focused to an EO crystal to obtain a THz temporal waveform which leads to THz spectrum with Fourier transform. The timing measurement between CTR and a probe laser was realized with OTR using a same optical photodiode. In this conference, we will describe details of our linac and results of the THz-TDS experiment.
	Slides MOOBA03 [3.342 MB]

MOOAC01	The European XFEL LLRF System	LLRF, cavity, cryomodule, klystron	55
	J. Branlard, G. Ayvazyan, V. Ayvazyan, M.K. Grecki, M. Hoffmann, T. Jeżyński, I.M. Kudla, T. Lamb, F. Ludwig, U. Mavrič, S. Pfeiffer, H. Schlarb, Ch. Schmidt, H.C. Weddig, B.Y. Yang DESY, Hamburg, Germany P. Barmuta, S. Bou Habib, L. Butkowski, K. Czuba, M. Grzegrzółka, E. Janas, J. Piekarski, I. Rutkowski, D. Sikora, L. Zembala, M. Żukociński Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland W. Cichalewski, K. Gnidzińska, W. Jałmużna, D.R. Makowski, A. Mielczarek, A. Napieralski, P. Perek, A. Piotrowski, T. Pożniak, K.P. Przygoda TUL-DMCS, Łódź, Poland S. Korolczuk, J. Szewiński The Andrzej Soltan Institute for Nuclear Studies, Centre Świerk, Świerk/Otwock, Poland K. Oliwa, W. Wierba IFJ-PAN, Kraków, Poland
	The European X-ray free electron laser accelerator consists of 800 superconducting cavities grouped in 25 RF stations. The challenges associated with the size and complexity of this accelerator required a high-precision, modular and scalable low level RF (LLRF) system. TheμTCA technology (uTCA) was chosen to support this system and adapted for RF standards. State-of-the-art hardware development in close collaboration with the industry allowed for the system continuity and maintainability. The complete LLRF system design is now in its final phase and the designed hardware was installed and commissioned at FLASH. The uTCA hardware system, measurement results and system performance validation will be shown. Operational strategy and plans for future automation algorithms for performance optimization will also be presented in this paper.
	Slides MOOAC01 [12.188 MB]

MOEPPB014	Time Jitter Measurements in Presence of a Magnetic Chicane in the FERMI@elettra Linac	electron, linac, FEL, dipole	109
	G. Penco, P. Craievich, S. Di Mitri, M.M. Milloch, F. Rossi ELETTRA, Basovizza, Italy
	Accurate and highly stable temporal synchronization between an electron bunch and a pulse from an external seed laser is one of the key requirements for successful operation of a seeded FEL in the XUV and soft x-ray regime. These requirements become more stringent when the electron bunch is longitudinally compressed to sub-ps durations in order to increase the current for more efficient FEL action. In this paper we present experimental measurements of the electron bunch arrival time jitter after the first magnetic compressor of FERMI@Elettra seeded FEL as a function of the compression factor. The experimental behavior of the pulse-to-pulse time jitter agrees both with results from tracking code simulations and with predictions from an analytical approach that takes into account the different sources of time jitter in FERMI, namely the photoinjector drive laser, the RF accelerating cavity phases and voltages, and fluctuations in the chicane bending magnet currents. We also present predictions for the expected arrival time jitter in the final configuration of FERMI that includes two bunch compressors and for which the synchronization requirement is of order 100 fs or better.

MOPPC056	The SolMaxP Code	plasma, simulation, target, beam-transport	259
	A. Chancé, N. Chauvin, R.D. Duperrier CEA/DSM/IRFU, France
	In modern sciences, use of high performance computing (HPC) has become a necessity to move forward in the modeling of complex systems. For large-scale instruments like accelerators, HPC permits the virtual prototyping of very onerous parts and, thus, helps to reduce development costs. The SolMaxP code (for Solving Maxwell in Plasma) has been developed to allow complex simulations of multi-species plasma coupled with electromagnetic fields, whether the electromagnetic background is or is not self-consistent with the plasma dynamics. This paper presents the main algorithm of the code and gives several examples of applications.

MOPPD004	oPAC - Optimizing Accelerators through International Collaboration	simulation, controls, instrumentation, emittance	373
	C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom C.P. Welsch The University of Liverpool, Liverpool, United Kingdom
	Funding: Work supported by the European Union under contract PITN-GA-2011-289485. The optimization of the performance of any particle accelerator critically depends on an in-depth understanding of the beam dynamics in the machine and the availability of simulation tools to study and continuously improve all accelerator components. It also requires a complete set of beam diagnostics methods to monitor all important machine and beam parameters with high precision and a powerful control and data acquisition system. Within the oPAC project all these aspects will be closely linked with the aim to optimize the performance of present and future accelerators that lie at the heart of many research infrastructures. The project brings together 22 institutions from around the world. With a project budget of 6 M€, it is one of the largest research and training networks ever funded by the EC. This contribution gives an overview of the network's broad research program and summarizes the training events that will be organized by the consortium within the next 4 years.

MOPPD006	Commissioning of the 2MeV Electron Cooler for COSY / HESR	electron, high-voltage, solenoid, gun	379
	V. Kamerdzhiev, J. Dietrich FZJ, Jülich, Germany V.N. Bocharov, M.I. Bryzgunov, A.D. Goncharov, V.M. Panasyuk, V.V. Parkhomchuk, V.B. Reva, D.N. Skorobogatov BINP SB RAS, Novosibirsk, Russia
	The new electron cooler for COSY is built at BINP Novosibirsk. Electron beam commissioning is in progress. Installation in COSY and commissioning with proton beam is scheduled for the beginning of 2012. Beam cooling with up to 3 A of electron current at up to 2 MeV is expected to boost the luminosity in the entire energy range of COSY by counteracting the effects caused by dense targets interacting with the circulating beam. Furthermore, the 2 MeV electron cooler can be used for beam cooling at injection energy in the HESR ring in the FAIR project. The electron beam is guided by a solenoidal magnetic field all the way from the electron gun to the collector. A cascade transformer provides power to numerous high voltage sections, short solenoids, and the collector inside a pressure vessel filed with SF6 gas. Commissioning results are reported.

MOPPD011	Analysis of Frequency Spectrum of Bunched Beam Related to Transverse Laser Cooling*	synchrotron, betatron, coupling, ion	391
	K. Jimbo Kyoto University, Institute for Advanced Energy, Kyoto, Japan Z.Q. He TUB, Beijing, People's Republic of China M. Nakao, A. Noda, H. Souda, H. Tongu Kyoto ICR, Uji, Kyoto, Japan
	Using synchro-betatron coupling, transverse laser cooling is pursued at an ion storage/cooler ring, S-LSR, Kyoto University. A bunched 40 keV 24Mg+ beam was cooled by a co-propagating laser of 280 nm wavelength. Synchrotron oscillation in the longitudinal direction and betatron oscillation in the horizontal direction were intentionally coupled by an RF drift tube located at the finite dispersive section (D =1.1 m) where longitudinal cooling force was transmitted to the horizontal direction.* Analyzing bunched Schottky signals, which represents longitudinal physical quantities of the beam, we try to obtain an evidence of synchro-betatron coupling and accordingly laser cooling of the beam in the transverse direction. * H. Okamoto, Phys. Rev. E 50, 4982 (1994)

MOPPD012	Challenge for More Efficient Transverse Laser Cooling for Beam Crystallization	synchrotron, ion, simulation, betatron	394
	A. Noda, M. Nakao, H. Souda, H. Tongu Kyoto ICR, Uji, Kyoto, Japan M. Grieser MPI-K, Heidelberg, Germany Z.Q. He TUB, Beijing, People's Republic of China K. Ito, H. Okamoto, K. Osaki HU/AdSM, Higashi-Hiroshima, Japan K. Jimbo Kyoto University, Institute for Advanced Energy, Kyoto, Japan Y. Yuri JAEA/TARRI, Gunma-ken, Japan
	Funding: Work supported by Advanced Compact Accelerator Development project by MEXT. Also supported by GCOE project at Kyoto University, The next generation of Physics-Spun from Universality and Emergency. At S-LSR in ICR, Kyoto University, Mg ion beam has been successfully laser cooled both in longitudinal* and transverse** directions. The cooling rate, however, is not strong enough to realize the crystalline beam due to the heating because of intra-beam scattering (IBS) effect. So as to suppress this IBS, reduction of the beam intensity is inevitable, which however, had resulted in poor S/N ratio for observation of the transverse beam size. In the present paper, we would like to describe a new beam scraping scheme, which selects out the beams in the distribution tail of the transverse phase space keeping the beam density in the core part by simultaneous application of multi-dimensional laser cooling and beam scraping. The strategy to reduce the beam intensity and hence beam heating due to IBS by a controlled scraping of the outskirt beam keeping the beam density at core part almost the same, has been searched by combination of the beam experiments and computer simulations. * M. Tanabe et al., Applied Physics Express 1, 028001 (2008). ** M. Nakao et al., submitted to PRST-AB.

MOPPD013	Observation of 2-Component Bunched Beam Signal with Laser Cooling	betatron, ion, coupling, injection	397
	H. Souda, M. Nakao, A. Noda, H. Tongu Kyoto ICR, Uji, Kyoto, Japan M. Grieser MPI-K, Heidelberg, Germany Z.Q. He TUB, Beijing, People's Republic of China K. Ito, H. Okamoto HU/AdSM, Higashi-Hiroshima, Japan K. Jimbo Kyoto University, Institute for Advanced Energy, Kyoto, Japan Y. Yuri JAEA/TARRI, Gunma-ken, Japan
	Funding: Work supported by Advanced Compact Accelerator Development Project of MEXT, Global COE program "The Next Generation of Physics, Spun from Universality and Emergence" and Grant-in-Aid for JSPS Fellows. Longitudinal beam temperature during a laser cooling was measured through bunch length measurement at S-LSR. 40keV 24Mg+ beams were bunched by an RF voltage with a harmonic number of 5 and were cooled by a co-propagating laser with a wavelength of 280nm. Bunch length was measured by time-domain signal from a pair of parallel-plate electrostatic pickups with a length of 140mm. Injected non-cooled beams gave a bunch length of 2.5m (2-σ) and cooled beam has a 2-component of broad and sharp distribution. Broad distribution had a longitudinal length of 2.2m, which is close to that of initial beam. The length of the sharp distribution shrunk to 0.25m and is considered as a cooled part. Capture efficiency of cooling, which represents the ratio of the particle numbers of cooled part and the total particle number, varies by the change of the detuning of the laser (fixed frequency or scanning). With scanning range of 2GHz, capture efficiency was improved from 66% to 92%, whereas the bunch became longer by 10% with scanning. Approach to improve the number of cooled particle and cut uncooled part* will be applied to attain a strong signal with a low-current beam with a low temperature. * J. S. Hangst et al., Phys. Rev. Lett. 74, 4432 (1995). ** A. Noda et al., these proceedings.

MOPPD036	Gabor Lens Focusing for Medical Applications	ion, proton, space-charge, focusing	442
	J.K. Pozimski, M. Aslaninejad Imperial College of Science and Technology, Department of Physics, London, United Kingdom
	The widespread introduction of Hadron therapy for cancer treatment is inhibited by the large costs for the accelerator and treatment facility and the subsequent maintenance costs which reflects into the cost per treatment. In the long term future (laser) plasma wakefield accelerated hadrons could offer compact treatment devices with significantly reduced treatment costs. In the moment the particle distributions produced by such accelerators do not fulfill the medical requirements by far. Never the less steady progress on the field might change the situation in the future. Beside the reliable production of a sufficient number of ions at the required energy the formation of a particle beam suitable for treatment from the burst of ions created in the acceleration process is one of the major challenges. While conventional optical systems will be operating at the technical limits which would be contradictory to the cost argument, space charge lenses of the Gabor type might be a cost effective alternative. In this paper a beam line consisting of such lenses will be presented together with particle transport simulations.

MOPPP004	Further Study on Fast Cooling in Compton Storage Rings	electron, storage-ring, simulation, photon	571
	E.V. Bulyak NSC/KIPT, Kharkov, Ukraine J. Urakawa KEK, Ibaraki, Japan F. Zimmermann CERN, Geneva, Switzerland
	Compton sources can produce gamma-ray photons of ultimate intensity, but suffer from the large recoils experienced by the circulating electrons scattering off the laser photons. We have previously proposed a scheme called asymmetric fast cooling to reduce the beam energy spread in Compton rings. This report presents results of further studies on the fast cooling. In particular, we show that (1) a proper asymmetric setup of the scattering point results in significant reduction of the quantum losses of electrons in Compton rings with moderate energy acceptance, and (2) the optimized pulsed mode of operation in synchrotron-dominated rings enhances the overall performance of such gamma-ray sources. Theoretical results presented are in good accordance with numerical simulations. We discuss the performance of an existing storage ring such as KEK ATF DR equipped with an optical cavity and presently available laser system.

MOPPP005	Feasibility of THz Source Based on Coherent Smith-Purcell Radiation Generated by Femtosecond Electron Bunches in Super-Radiant Regime	radiation, electron, simulation, gun	574
	L.G. Sukhikh, K.P. Artyomov, A. Potylitsyn Tomsk Polytechnic University, Tomsk, Russia A.S. Aryshev, J. Urakawa KEK, Ibaraki, Japan V. Karataev JAI, Egham, Surrey, United Kingdom
	Nowadays there is a big interest to THz radiation that is a promising tool for investigations in material science, in biology, medicine and other fields. THz radiation for users is mostly produced by Light Sources that are big and complex machines. Because of this there are numerous activities in research and development of a compact THz source. One of the trends is based on using different types of radiation generated in coherent regime by short electron bunches. The promising radiation mechanism is coherent Smith-Purcell radiation (CSPR) that has monochromatic angular distribution and that is generated while the bunch travels in a vicinity of a grating. In this report we present simulated characteristics of frequency-locked coherent Smith-Purcell radiation (super-radiant regime) generated by a train of short (hundreds of femtosecond) 10 MeV electron bunches with THz spacing. The simulations are performed for different grating profiles and parameters using existing CSPR models and Particle-in-Cell simulation code. We also discuss the feasibility of the THz source based on CSPR and status of the experiment that is prepared at LUCX facility at KEK after the upgrade.

MOPPP006	Inverse Cherenkov Radiation based on Smith-Purcell Effect	radiation, electron, linac, gun	577
	K. Kan, T. Kondoh, K. Norizawa, A. Ogata, J. Yang, Y. Yoshida ISIR, Osaka, Japan M. Hangyo ILE Osaka, Suita, Japan R. Kuroda, H. Toyokawa AIST, Tsukuba, Ibaraki, Japan
	Inverse Cherenkov radiation based on Smith-Purcell effect using metamaterial was investigated. A metallic grating and picosecond electron bunch of 27 MeV beam energy from a thermionic DC gun and linac were used for the inverse radiation. The frequency spectra in terahertz (THz) range were measured by a Michelson interferometer experimentally. Peaks of discrete component in the spectra shifted continuously according to the radiation angles, e. g. discrete peak changing from 0.117 to 0.085 THz with radiation angle along the electron bunch from 102 to 134 degree (backward) using a 2-mm-period metallic grating. In this presentation, experiment using another electron bunch generated by a photocathode RF gun linac will be reported.

MOPPP008	Hard X-ray Generation Experiment at Tsinghua Thomson Scattering X-Ray Source	electron, photon, scattering, background	583
	Y.-C. Du, H. Chen, Q. Du, Hua, J.F. Hua, W.-H. Huang, H.J. Qian, C.-X. Tang, H.S. Xu, L.X. Yan, Z. Zhang TUB, Beijing, People's Republic of China
	Recently, there is increasing industrial and scientific interesting in ultra-fast, high peak brightness, tunable energy and polarization, monochromatic hard X-ray source. The X-ray source based on the Thomson scattering between the relativistic electron beam and TW laser pulse is the suitable candidate for its compact and affordable alternatives for high brightness hard monochromatic X-ray generation. Accelerator laboratory in Tsinghua University al so proposed and built Tsinghua Thomson scattering X-ray source. The hard x-ray pulse has been generated in experiment with 47 MeV electron and 20 TW laser in this year, and the parameters of the X-ray have been measured preliminarily. The experimental results are presented and discussed in this paper.

MOPPP009	X-Ray Spectra Reconstruction of Thomson Scattering Source From Analysis of Attenuation Data	scattering, photon, simulation, target	586
	Y.-C. Du, Hua, J.F. Hua, W.-H. Huang, C.-X. Tang, H.S. Xu, L.X. Yan, H. Zha, Z. Zhang TUB, Beijing, People's Republic of China
	Thomson scattering X-ray source, in which the TW laser pulse is scattered by the relativistic electron beam, can provide ultra short, monochromatic, high flux, tunable polarized hard X-ray pulse which is can widely used in physical, chemical and biological process research, ultra-fast phase contrast imaging, and so on. Since the pulse duration of X-ray is as short as picosecond and the flux in one pulse is high, it is difficult to measure the x-ray spectrum. In this paper, we present the X-ray spectrum measurement experiment on Tsinghua Thomson scattering. The preliminary experimental results shows the maximum X-ray energy is about 47 keV, which is agree well with the simulations.

MOPPP011	Narrow Band Optimization of a Compton Gamma-Ray Source Produced From an X-Band Linac	electron, simulation, emittance, linac	592
	F. Albert, S.G. Anderson, C.P.J. Barty, D.J. Gibson, F.V. Hartemann, R.A. Marsh, S.S.Q. Wu LLNL, Livermore, California, USA
	Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. Nuclear photonics is an emerging field of research that will require high precision gamma-ray (MeV) sources. In particular, nuclear resonance fluorescence applications necessitate a low (< 1%) relative gamma-ray spectral width. Within this context, Compton scattering, where laser photons are scattered off relativistic electron beams to produce tunable, collimated gamma rays, will produce the desired gamma-ray output. This paper will present the spectral narrowband optimization of such a light source currently being built at LLNL. In this case, PARMELA and elegant simulations of the full 250 MeV, high-gradient X-band linac provide the properties of the high brightness electron bunch. The electron beam simulations are then implemented into our newly developed weakly nonlinear Compton scattering code to produce theoretical gamma-ray spectra. The influence that the electron beam, laser beam and interaction geometry parameters have on the produced gamma-ray spectra will be shown with our simulations.

MOPPP029	Photocathodes at FLASH	cathode, electron, photon, gun	625
	S. Lederer, H. Hansen, H.-H. Sahling, S. Schreiber DESY, Hamburg, Germany P. Michelato, L. Monaco, D. Sertore INFN/LASA, Segrate (MI), Italy
	For several years, cesium telluride photocathodes have been successfully used in the photoinjector of the Free-Electron-Laser FLASH at DESY, Germany. They show a high quantum efficiency and long lifetime and produce routinely thousands of bunches per second with a single bunch charge mostly in the range of 0.3 to 1 nC. Recent studies on lifetime, quantum efficiency, dark current, and operating experience is reported. At DESY, a new preparation system has been set-up. First cathodes have been produced and tested.

MOPPP032	Longitudinal Phase Space Studies at the PITZ Facility	electron, radiation, gun, FEL	631
	M. Mahgoub, J.W. Bähr, H.-J. Grabosch, M. Groß, L. Hakobyan, G. Klemz, G. Kourkafas, M. Krasilnikov, D. Malyutin, A. Oppelt, M. Otevřel, B. Petrosyan, K. Rosbach, F. Stephan, G. Vashchenko DESY Zeuthen, Zeuthen, Germany I.I. Isaev MEPhI, Moscow, Russia Ye. Ivanisenko IERT, Kharkov, Ukraine M. Khojoyan ANSL, Yerevan, Armenia J. Li USTC/NSRL, Hefei, Anhui, People's Republic of China B. Marchetti INFN-Roma II, Roma, Italy D. Richter HZB, Berlin, Germany J. Rönsch-Schulenburg Uni HH, Hamburg, Germany
	Photoinjectors are a cornerstone for short-wavelength Free Electron Lasers (FELs) like FLASH and the European XFEL in Hamburg, Germany. The Photo Injector Test facility at DESY, location Zeuthen (PITZ), was built to develop and optimize such photoinjectors. The PITZ facility is capable of generating long trains of electron bunches, which can be accelerated up to ~25 MeV/c. Studying and optimizing the longitudinal properties of the electron bunch is an important topic at PITZ. A streak system consisting of Silica Aerogel radiators, optical transition radiation (OTR) screens, optical transmission line, and a streak camera is used to study the longitudinal properties with an accuracy of some ps. Due to the high radiation level in the facility, many of the lenses in the optical transmission line have turned brown, reducing the efficiency of the system. Some of the lenses were recovered by baking them up to 180°C. In contrast, few sensitive objective lenses can not be baked, rather they were recovered via exposure to infrared radiation with the proper wave length. An overview of the system, the difficulties, and the modifications needed to overcome the radiation effects are presented.

MOPPP035	Initial Emittance and Temporal Response Measurement for GaAs Based Photocathodes	electron, cathode, emittance, cavity	640
	S. Matsuba Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan Y. Honda, T. Miyajima, T. Uchiyama, M. Yamamoto KEK, Ibaraki, Japan X.G. Jin Institute for Advanced Research, Nagoya, Japan Y. Takeda Nagoya University, Nagoya, Japan
	For future light source based on Energy Recovery Linac (ERL) is planned in KEK. For the ERL, an ultra low emittance and fast temporal response and high current electron source is needed. To achieve these requirements, a high voltage DC gun with a Negative Electron Affinity photo-cathode is under development. In this development, it is important to investigate the performance of photo-cathodes. We have constructed an ERL gun test stand to measure emittance and temporal profile. We use a solenoid scan technique for emittance measurements and a deflecting cavity technique for temporal profile measurements. In this presentation, we introduce KEK ERL gun test stand and beam test results.

MOPPP038	Optics Design and Layout for the Electron Beam Test Facility at Daresbury Laboratory	gun, quadrupole, beam-transport, emittance	646
	D. Angal-Kalinin, J.W. McKenzie, B.L. Militsyn STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom J.K. Jones Cockcroft Institute, Warrington, Cheshire, United Kingdom
	An Electron Beam Test Facility (EBTF) is being developed at Daresbury Laboratory to provide the beam for industrial applications and as a front end of future light source facility test under consideration. The RF photoinjector will deliver ~6 MeV beam to industrial users* and will serve as an injector for the future light source facility under consideration at Daresbury*. The Photoinjector design in first phase consists of 2.5 cell RF gun (on loan from Strathclyde) to be driven by Ti:S laser. The photo injector design is aimed to deliver bunches with 10-250 pC bunch charge at low transverse emittances and short bunch lengths. The beam transport optics design described in this paper includes a dedicated diagnostics section capable of measuring ultra short and ultra low emittance bunches and transport to two user areas. P. McIntosh, these proceedings. ** J. Clarke, these proceedings.

MOPPP039	Masked Photocathode for Photoinjectors	electron, cathode, emittance, vacuum	649
	J. Qiang LBNL, Berkeley, California, USA
	Funding: This research was supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. This research used resources of the NERSC. In this paper, we propose using masked photocathode in photoinjector for generating high brightness electron beam. An electrode with small hole is used as a mask to shield a large size photocathode from accelerating vacuum chamber. Using a mask will significantly increase lifetime of a photocathode by rotating unexplored photocathode material behind the electrode into the hole. Furthermore, the mask helps reduce dark current or secondary electron emission from the photocathode material. It also provides a control of initial beam transverse emittances.

MOPPP041	Effect of Roughness on Emittance of Potassium Cesium Antimonide Photocathodes	emittance, cathode, electron, extraction	655
	T. Vecchione, J. Feng, H.A. Padmore, W. Wan LBNL, Berkeley, California, USA I. Ben-Zvi, M. Ruiz-Osés, L. Xue Stony Brook University, Stony Brook, USA D. Dowell SLAC, Menlo Park, California, USA T. Rao, J. Smedley BNL, Upton, Long Island, New York, USA
	Funding: This work was supported by the Director, Office of Science, Office of Basic Energy Sciences of the U. S. Department of Energy, under Contract DE-AC02-05CH11231, KC0407-ALSJNT-I0013, and DE-SC0005713 Here we present first measurements of the effect of roughness on the emittance of K2CsSb photocathodes under high fields. We show that for very thin cathodes the effect is negligible at up to 3 MV/m but for thicker and more efficient cathodes the effect becomes significant. We discuss ways to modify the deposition to circumvent this problem.

MOPPP042	Modeling Multi-bunch X-band Photoinjector Challenges	emittance, gun, electron, linac	658
	R.A. Marsh, S.G. Anderson, C.P.J. Barty, D.J. Gibson, F.V. Hartemann LLNL, Livermore, California, USA
	Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. An X-band test station is being developed at LLNL to investigate accelerator optimization for future upgrades to mono-energetic gamma-ray (MEGa-Ray) technology at LLNL. The test station will consist of a 5.5 cell X-band rf photoinjector, single accelerator section, and beam diagnostics. Of critical import to the functioning of the LLNL X-band system with multiple electron bunches is the performance of the photoinjector. In depth modeling of the Mark 1 LLNL/SLAC X-band rf photoinjector performance will be presented addressing important challenges that must be addressed in order to fabricate a multi-bunch Mark 2 photoinjector. Emittance performance is evaluated under different nominal electron bunch parameters using electrostatic codes such as PARMELA. Wake potential is analyzed using electromagnetic time domain simulations using the ACE3P code T3P. Beam-loading effects and low level rf compensation schemes are explored as well, using a semi-analytic formalism and computer algorithm. Plans for multi-bunch experiments and implementation of photoinjector advances for the Mark 2 design will also be discussed.

MOPPP045	Status of the Wisconsin SRF Gun	cavity, cathode, gun, solenoid	661
	R.A. Legg, J. Bisognano, M.J. Bissen, R.A. Bosch, D. Eisert, M.V. Fisher, M.A. Green, K. Jacobs, R.G. Keil, K.J. Kleman, J.G. Kulpin, G.C. Rogers, M.C. Severson UW-Madison/SRC, Madison, Wisconsin, USA D. Yavuz UW-Madison/PD, Madison, Wisconsin, USA
	Funding: The University of Wisconsin SRF electron gun program is supported by DOE Award DE-SC0005264. SRF electron guns hold out the promise of very bright beams for use in electron injectors, particularly for light source applications such as Free Electron Lasers. The University of Wisconsin is midway in a multi-year program to demonstrate a low frequency electron gun based on a quarter wave resonator cavity. The design includes active tuning and a high temperature superconducting solenoid for emittance compensation. We will report on the status of the 4 MeV SRF electron gun, including the cryomodule, the RF power coupler, the main RF power amplifier/low level RF control system, the photocathode laser system, and the diagnostic beamline. Installation is moving forward in a recently renovated experimental vault adjacent to the existing Aladdin synchrotron. First electron beam is expected in the summer 2012.

MOPPP046	RF Gun Photocathode Research at SLAC	gun, cathode, emittance, electron	664
	E.N. Jongewaard, R. Akre, A. Brachmann, W.J. Corbett, S. Gilevich, K. Grouev, P. Hering, P. Krejcik, J.R. Lewandowski, H. Loos, T. M. Montagne, J. Sheppard, P. Stefan, A.E. Vlieks, S.P. Weathersby, F. Zhou SLAC, Menlo Park, California, USA
	Funding: DOE contract DE-AC02-76SF00515. LCLS is presently operating with a third copper photocathode in the original rf gun, with a quantum efficiency (QE) of ~1x10^-4 and projected emittance eNx,y=0.45 μm at 250 pC bunch charge. The spare LCLS gun is installed in the SLAC Accelerator Structure Test Area (ASTA), processed to the design rf gradient of >120 MV/m. As part of a wider photocathode R&D program, a UV laser system and additional gun diagnostics are being installed at ASTA to measure QE, QE lifetime, and electron beam emittance under a variety of operating conditions. The near-term goals are to test and verify the spare photocathode production/installation sequence, including transfer from the final holding chamber to the rf gun. Mid- and longer-term goals include development of a rigorous understanding of plasma and laser-assisted surface conditioning and investigation of new, high-QE photocathode materials. In parallel, an x-ray photoemission spectroscopy station is nearing completion, to analyze Cu photocathode surface chemistry. In this paper we review the status and anticipated operating parameters of ASTA and the spectroscopy test chamber.

MOPPP074	Magnetic Field Measurement for a THz Undulator Using the Vibrating Wire Method	undulator, electron, radiation, resonance	732
	S. Kashiwagi, H. Hama, F. Hinode, M. Kawai, X. Li, T. Muto, K. Nanbu, Y. Tanaka Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
	Funding: This work is supported by the Ministry of Education, Science, Sports and Culture, Grant-in-Aid for Scientific Research (S), Contract #20226003. We constructed the undulator that is a basically a Halbach planer type for a generation of intense coherent terahertz radiation from the very short electron bunch. The period length of the undulator and the number of periods are 100 mm and 25, respectively. Its maximum magnetic field is 0.41 T and the K-value is 3.82 with 54 mm gap. The vibrating wire method is studied to measure the periodic magnetic field of the undulator. By measuring amplitudes and phases of standing waves excited on the wire by the Lorentz force between AC current and magnetic field, we can reconstruct the magnetic field distribution along the wire. The theoretical analysis has been performed for the THz undulator and derived a relation between a reproducibility of undulator field and the number of the harmonic mode to use for the reconstruction. A model experiment was demonstrated using 20cm wire and one pair of permanent magnet block. The theoretical study and the results of model experiment using the vibrating wire method will be shown in this conference.

MOPPP091	Recent Developments at the DELTA THz Beamline	electron, radiation, storage-ring, undulator	768
	P. Ungelenk, M. Bakr, H. Huck, M. Höner, S. Khan, R. Molo, A. Nowaczyk, A. Schick, M. Zeinalzadeh DELTA, Dortmund, Germany
	Funding: Work supported by DFG, BMBF, and by the Federal State NRW. During 2011, a new dedicated THz beamline has been constructed and commissioned at DELTA, a 1.5 GeV synchrotron light source operated by the TU Dortmund University. This beamline enables extracting and detecting coherent THz pulses caused by a laser-induced density modulation of the electron bunches. Ongoing experiments aim at characterizing the THz radiation as well as investigating the evolution of the density modulation over subsequent revolutions following the initial laser-electron interaction in an undulator.

MOPPR007	Investigation of Techniques for Precise Compton Polarimetry at ELSA	electron, polarization, photon, simulation	783
	R. Zimmermann, W. Hillert ELSA, Bonn, Germany
	Funding: Work supported by DFG within SFB/TR16 A Compton polarimeter is currently being installed at the Electron Stretcher Facility ELSA to monitor the degree of polarization of the stored electron beam. For this purpose, circularly polarized light that is emitted by a laser and backscattered off the beam has to be detected. When the polarization of the laser light is switched from left-hand to right-hand circular polarization, the spatial distribution of the backscattered photons is shifted. The extent of this modification is a measure of the beam's polarization degree. Two different experimental techniques that are suitable for a measurement of the effect were compared and evaluated closer through numerical simulations that will be presented in this contribution.

MOPPR016	Femtosecond Level Electron Bunch Diagnostic at Quasi – CW SRF Accelerators: Test Facility ELBE	electron, diagnostics, SRF, photon	810
	M. Gensch, C. Kaya, U. Lehnert, P. Michel, Ch. Schneider, W. Seidel HZDR, Dresden, Germany G. Geloni European XFEL GmbH, Hamburg, Germany M. Helm FZD, Dresden, Germany H. Schlarb, A. Shemmary, N. Stojanovic DESY, Hamburg, Germany
	Funding: BMBF through the PIDID proposal and HGF through the ARD initiative At the srf based prototype cw accelerator ELBE a new electron beamline, providing for femtosecond electron bunches with nC bunch charges and repetition rates in the 1 – 200 KHz regime and with pC bunch charge and repetition rates of 13 MHz is currently constructed. The 40 MeV electrons will be used in photon-electron interaction experiments with TW and PW class laser and the generation of broad band and narrow bandwidth coherent THz pulses. In this paper we outline ideas for novel online diagnostics of the electron bunch properties (e.g. arrival time and bunch form) based on the time and frequency domain analysis of the emitted coherent THz radiation but also based on direct measurements by e.g. electro-optic sampling. The suitability of ELBE as a testbed for diagnostic of future cw X-ray photon sources (e.g. energy recovery linacs) will be discussed.

MOPPR018	Beam Halo Monitor for FLASH and the European XFEL	electron, diagnostics, free-electron-laser, pick-up	816
	A. Ignatenko, N. Baboi, O. Hensler, M. Schmitz, K. Wittenburg DESY, Hamburg, Germany H.M. Henschel, W. Lange, W. Lohmann DESY Zeuthen, Zeuthen, Germany A. Ignatenko BTU, Cottbus, Germany S. Schuwalow Uni HH, Hamburg, Germany
	The Beam Halo Monitor for Free-electron Laser in Hamburg (FLASH) based on pCVD diamond and monocrystalline artificial sapphire sensors has been successfully commissioned in September 2009. It is a part of the beam dump diagnostics and ensures safe beam dumping. Its description and the experience gained during its operation are given. The ideas on the design and aspects of operation of the similar systems at FLASH II and the European XFEL are presented.

MOPPR034	A Laser Wire System at Electron Beam Transport Line in BEPCII	electron, photon, positron, simulation	852
	C. Zhang, J. Cao, Q.Y. Deng, Y.F. Sui IHEP, People's Republic of China
	Funding: National Natural Science Foundation of China A Laser Wire system is under development at transport line in BEPCII (Beijing Electron Positron Collider). The structure of whole system is briefly described in this paper. Some work on laser and detector are presented. We also discussed the challenge of Laser Wire and some other things that can affect measurement. According to the plan, the Laser Wire will be installed in electron beam transport line in the summer of 2012.

MOPPR071	Initial Results of Transverse Beam Profile Measurements Using a LYSO:Ce Crystal	radiation, diagnostics, electron, controls	951
	A.S. Johnson, A.H. Lumpkin, T.J. Maxwell, J. Ruan, J.K. Santucci, C.C. Tan, R.M. Thurman-Keup, M. Wendt Fermilab, Batavia, USA
	A prototype transverse beam profile monitor for eventual use at the Advanced Superconducting Test Accelerator (ASTA) has been tested at the Fermilab A0 Photoinjector. Results from low-charge (20 pC) studies indicate that a LYSO:Ce scintillator will be a viable replacement for a YAG:Ce scintillator when using intercepting radiation convertor screens for beam profiling. We will also describe the planned implementation of LYSO:Ce crystals to mitigate the coherent optical transition radiation due to the microbunching instability through the use of band-pass filters and specially timed cameras.

MOPPR072	Fermilab PXIE Beam Diagnostics Development and Testing at the HINS Beam Facility	diagnostics, linac, emittance, rfq	954
	V.E. Scarpine, B.M. Hanna, V.A. Lebedev, L.R. Prost, A.V. Shemyakin, J. Steimel, M. Wendt Fermilab, Batavia, USA
	Funding: This work was supported by the U.S. Department of Energy under contract No. DE-AC02-07CH11359. Fermilab is planning the construction of a prototype front end of the Project X linac. The Project X Injector Experiment (PXIE) is expected to accelerate 1 mA cw H⁻ beam up to 30 MeV. Some of the major goals of the project are to test a cw RFQ and H⁻ source, a broadband bunch-by-bunch beam chopper and a low-energy superconducting linac. The successful characterization and operation of such an accelerator places stringent requirements on beam line diagnostics. These crucial beam measurements include bunch currents, beam orbit, beam phase, bunch length, transverse profile and emittance, beam halo and tails, as well as the extinction performance of the broadband chopper. This paper presents PXIE beam measurement requirements and instrumentation development plans. Also presented are plans to test many of these instruments at the Fermilab High Intensity Neutrino Source (HINS) beam facility. Since HINS is already an operational accelerator, utilizing HINS for instrumentation testing allows for quicker development of the required PXIE diagnostics.

MOPPR075	Status of the APEX Beam Diagnostic and First Measurements	diagnostics, cathode, electron, gun	963
	D. Filippetto, M.J. Chin, C.W. Cork, S. De Santis, L.R. Doolittle, W.E. Norum, C. F. Papadopoulos, G.J. Portmann, D.G. Quintas, F. Sannibale, R.P. Wells, M.S. Zolotorev LBNL, Berkeley, California, USA
	The APEX project aims to the construction of a high brightness high repetition rate photo-injector at LBNL. In its first phase a 750 keV electron bunch is produced at a maximum repetition rate of 1 MHz, with an adjustable charge per bunch spanning the pC-to-nC region. A load lock system is foreseen to test different cathodes without the need of breaking the vacuum and the downstream diagnostic is used to characterize the photo-emitted beam brightness. In the initial phase the main effort is directed toward the measurement of photocurrent, dark current, thermal emittance and electron beam kinetic energy. In a successive phase, diagnostic for full 6D phase space characterization of space charge dominated beams will be added to the beamline. We report and discuss the present diagnostic beamline layout, first beam measurements and future upgrades.

MOPPR083	Mechanical Design and Evaluation of the MP-11-like Wire Scanner Prototype	controls, linac, vacuum, neutron	984
	S. Rodriguez Esparza, J.D. Gilpatrick, M.E. Gruchalla, A.J. Maestas, J.P. Martinez, J.L. Raybun, F.D. Sattler, J.D. Sedillo, B.G. Smith LANL, Los Alamos, New Mexico, USA
	A wire scanner (WS) is a linearly actuated diagnostic device that uses fiber wires (such as Tungsten or Silicon Carbide) to obtain the position and intensity profile of the proton beam at the Los Alamos Neutron Science Center (LANSCE) particle accelerator. LANSCE will be installing approximately 86 new WS in the near future as part of the LANSCE Risk Mitigation project. These 86 new WS include the replacement of many current WS and some newly added to the current linear accelerator and other beam lines. The reason for the replacement and addition of WS is that many of the existing actuators have parts that are no longer readily available and are difficult to find, thus making maintenance very difficult. One of the main goals is to construct the new WS with as many commercially-available-off-the-shelf components as possible. In addition, faster beam scans (both mechanically and in term of data acquisition) are desired for better operation of the accelerator. This document outlines the mechanical design of the new MP-11-like WS prototype and compares it to a previously built and tested SNS-like WS prototype.

TUYB01	Proton Beam Acceleration with Circular Polarized Laser Pulses	proton, electron, plasma, ion	1045
	X.Q. Yan, J.E. Chen, C. Lin, Y.R. Lu, H. Wang PKU/IHIP, Beijing, People's Republic of China Z.Y. Guo IHEP, Beijing, People's Republic of China
	This presentation should describe the use of circular polarized laser pulses for phase-stable acceleration of proton beams. The principles of the technique should be explained, with comparisons and contrasts made with similar techniques. The potential for production of high-intensity, mono-energetic proton beams should be discussed, and the results of analytical, simulation, and experimental studies presented.
	Slides TUYB01 [7.922 MB]

TUYB02	Manufacture and Testing of Optical-scale Accelerator Structures from Silicon and Silica	electron, coupling, acceleration, vacuum	1050
	R.J. England, E.R. Colby, R. Laouar, C. McGuinness, B. Montazeri, R.J. Noble, K. Soong, J.E. Spencer, D.R. Walz, Z. Wu SLAC, Menlo Park, California, USA R.L. Byer, C.M. Chang, K.J. Leedle, E.A. Peralta Stanford University, Stanford, California, USA B.M. Cowan Tech-X, Boulder, Colorado, USA M. Qi Purdue University, West Lafayette, Indiana, USA
	We report on recent progress in the design, manufacture and testing of optical-scale accelerator structures made from silicon and silica. The potential of these structures for the development of extremely compact, efficient, and low cost accelerators producing attosecond electron pulses will be discussed, together with various possible applications.
	Slides TUYB02 [17.226 MB]

TUOAB01	Timing and Synchronization for the APS Short Pulse X-ray Project	cavity, feedback, LLRF, storage-ring	1077
	F. Lenkszus, N.D. Arnold, T.G. Berenc, G. Decker, E.M. Dufresne, R.I. Farnsworth, Y.L. Li, R.M. Lill, H. Ma ANL, Argonne, USA J.M. Byrd, L.R. Doolittle, G. Huang, R.B. Wilcox LBNL, Berkeley, California, USA
	Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. The Short-Pulse X-ray (SPX) project, which is part of the APS upgrade, will provide intense, tunable, high-repetition-rate picosecond x-ray pulses through the use of deflecting cavities operating at the 8th harmonic of the storage-ring rf. Achieving this picosecond capability while minimizing the impact to other beamlines outside the SPX zone imposes demanding timing and synchronization requirements. For example, the mismatch between the upstream and downstream deflecting cavities' rf field phase is specified to be less than 0.077 degrees root mean squared (rms) at 2815 MHz (~77 femtoseconds). Another stringent requirement is to synchronize beamline pump-probe lasers to the SPX x-ray pulse to 400 femtoseconds rms. To achieve these requirements we have entered into a collaboration with the Beam Technology group at LBNL. They have developed and demonstrated a system for distributing stable rf signals over optical fiber capable of achieving less than 20 femtoseconds rms drift and jitter over 2.2 km over 60 hours. This paper defines the overall timing/synchronization requirements for the SPX and describes the plan to achieve them. R. Wilcox et al. Opt. Let. 34(20), Oct 15, 2009
	Slides TUOAB01 [2.515 MB]

TUOBB01	A European Proposal for the Compton Gamma-ray Source of ELI-NP	photon, electron, emittance, scattering	1086
	L. Serafini, I. Boscolo, F. Broggi, V. Petrillo Istituto Nazionale di Fisica Nucleare, Milano, Italy O. Adriani, G. Graziani, G. Passaleva INFN-FI, Sesto Fiorentino, Italy S. Albergo, A. Tricomi INFN-CT, Catania, Italy D. Alesini, M.P. Anania, A. Bacci, R. Bedogni, M. Bellaveglia, C. Biscari, R. Boni, M. Boscolo, M. Castellano, E. Chiadroni, A. Clozza, E. Di Pasquale, G. Di Pirro, A. Drago, A. Esposito, M. Ferrario, A. Gallo, G. Gatti, A. Ghigo, F. Marcellini, C. Maroli, G. Mazzitelli, E. Pace, L. Pellegrino, R. Ricci, M. Serio, F. Sgamma, B. Spataro, A. Stecchi, A. Stella, P. Tomassini, C. Vaccarezza, S. Vescovi, F. Villa INFN/LNF, Frascati (Roma), Italy D. Angal-Kalinin, J.A. Clarke, B.D. Fell, A.R. Goulden, J.D. Herbert, S.P. Jamison, P.A. McIntosh, R.J. Smith, S.L. Smith STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom P. Antici, M. Coppola, L. Lancia, A. Mostacci, L. Palumbo URLS, Rome, Italy N. Bliss, B.G. Martlew STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom P. Cardarelli, M. Gambaccini INFN-Ferrara, Ferrara, Italy L. Catani, A. Cianchi INFN-Roma II, Roma, Italy I. Chaikovska, O. Dadoun, A. Stocchi, A. Variola, Z.F. Zomer LAL, Orsay, France C. De Martinis INFN/LASA, Segrate (MI), Italy F. Druon, P. Fichot ILE, Palaiseau Cedex, France E. Iarocci University of Rome "La Sapienza", Rome, Italy M. Migliorati Rome University La Sapienza, Roma, Italy A.-S. Müller IN2P3, Paris, France V. Nardone Università di Roma I La Sapienza, Roma, Italy C. Ronsivalle ENEA C.R. Frascati, Frascati (Roma), Italy M. Veltri Uniurb, Urbino (PU), Italy
	A European proposal is under preparation for the Compton gamma-ray Source of ELI-NP. In the Romanian pillar of ELI (the European Extreme Light Infrastructure) an advanced gamma-ray beam is foreseen, coupled to two 10 PW laser systems. The photons will be generated by Compton back-scattering in the collision between a high quality electron beam and a high power laser. A European collaboration formed by INFN, Univ. of Roma La Sapienza, Orsay-LAL of IN2P3, Univ. de Paris Sud XI and ASTeC at Daresbury, is preparing a TDR exploring the feasibility of a machine expected to achieve the Gamma-ray beam specifications: energy tunable between 1 and 20 MeV, narrow bandwidth (0.3%) and high spectral density, 10⁴ photons/sec/eV. We will describe the lay-out of the 720 MeV RF Linac and the collision laser with the associated optical cavity, as well as the optimized beam dynamics to achieve maximum phase space density at the collision, taking into account beam loading and beam break-up due to the acceleration of long bunch trains. The predicted gamma-ray spectra will be evaluated as the gamma photons collimators background. An option for electron bunches recirculation will also be illustrated.
	Slides TUOBB01 [5.099 MB]

TUOBB03	Status of the FERMI@Elettra Project	FEL, electron, radiation, photon	1092
	M. Svandrlik, E. Allaria, L. Badano, S. Bassanese, F. Bencivenga, E. Busetto, C. Callegari, F. Capotondi, D. Castronovo, M. Coreno, P. Craievich, I. Cudin, G. D'Auria, M. Dal Forno, M.B. Danailov, R. De Monte, G. De Ninno, A.A. Demidovich, M. Di Fraia, S. Di Mitri, B. Diviacco, A. Fabris, R. Fabris, W.M. Fawley, M. Ferianis, E. Ferrari, L. Fröhlich, P. Furlan Radivo, G. Gaio, L. Giannessi, R. Gobessi, C. Grazioli, E. Karantzoulis, M. Kiskinova, M. Lonza, B. Mahieu, C. Masciovecchio, S. Noè, F. Parmigiani, G. Penco, E. Principi, F. Rossi, L. Rumiz, C. Scafuri, S. Spampinati, C. Spezzani, C. Svetina, M. Trovò, A. Vascotto, M. Veronese, R. Visintini, M. Zaccaria, D. Zangrando, M. Zangrando ELETTRA, Basovizza, Italy
	Funding: The work was supported in part by the Italian Ministry of University and Research under grants FIRB-RBAP045JF2 and FIRB-RBAP06AWK3. The FERMI@Elettra seeded Free Electron Laser has provided the first photons to the experimental stations during 2011. The first FEL line in operation is FEL-1, covering the wavelength range between 100 nm and 20 nm. The facility will be opened to users by the end of 2012. In the meantime the installation of the second FEL line, FEL-2 covering the higher energy range down to 4 nm, is progressing on schedule and first tests have started. A description of the status of the project is presented here.
	Slides TUOBB03 [5.316 MB]

TUEPPB010	Oscillator Seeding of a High Gain Harmonic Generation FEL in a Radiator-first Configuration	FEL, electron, radiation, bunching	1137
	P.R. Gandhi, J.S. Wurtele UCB, Berkeley, California, USA G. Penn, M.W. Reinsch LBNL, Berkeley, California, USA
	A longitudinally coherent X-ray pulse from a high repetition rate free electron laser (FEL) is desired for a wide variety of experimental applications. However, generating such a pulse with a repetition rate greater than ~1 MHz is a significant challenge. The desired high rep rate sources, primarily high harmonic generation with intense lasers in gases or plasmas, do not exist now, and, for the multi-MHz bunch trains that superconducting accelerators can potentially produce, are likely not feasible with current technology. In this paper, we propose to place an oscillator downstream of a radiator. The oscillator generates radiation that is used as a seed for a high gain harmonic generation (HGHG) FEL which is upstream of the oscillator. For the first few pulses the oscillator builds up power and, until power is built up, the radiator has no HGHG seed. As power in the oscillator saturates, the HGHG is seeded and power is produced. The dynamics and stability of this radiator-first scheme is explored analytically and numerically. A single-pass map is derived using a semi-analytic model for FEL gain and saturation. Iteration of the map is shown to be in good agreement with simulations.

TUEPPB011	Echo Enabled High Mode Generation for X-ray FELs	electron, bunching, FEL, free-electron-laser	1140
	E. Hemsing SLAC, Menlo Park, California, USA A. Marinelli UCLA, Los Angeles, California, USA
	Funding: Work supported by U.S. DOE under Contract Nos. DE-AC02-76SF00515 and DE-FG02-07ER46272. We describe a simple technique based on a modified echo-enabled harmonic generation (EEHG) scheme to manipulate the three-dimensional electron beam microbunching distribution in order to generate higher-order optical modes in an FEL. As with EEHG, the concept uses two modulators and two chicanes to produce microbunching. However, in one of the modulators, the resonant interaction with the laser has a well-defined transverse structure that becomes strongly correlated to the longitudinal microbunching distribution. Both high-harmonic frequencies and high transverse mode numbers can be generated through a transversely-dependent echo effect.

TUEPPB015	Generation of Narrow-Band Coherent Tunable Terahertz Radiation using a Laser-Modulated Electron Beam	electron, radiation, undulator, bunching	1146
	M.P. Dunning, C. Hast, E. Hemsing, R.K. Jobe, D.J. McCormick, J. Nelson, T.O. Raubenheimer, K. Soong, Z.M. Szalata, D.R. Walz, S.P. Weathersby, D. Xiang SLAC, Menlo Park, California, USA
	Funding: Work supported by US DOE contract DE-AC02-76SF00515. The technical layout and initial results of an experiment to generate narrow-band, coherent, tunable terahertz (THz) radiation through the down-conversion of the frequency of optical lasers using a laser-modulated electron beam are described. In this experiment a 120 MeV electron beam is first energy modulated by two lasers with different wavelengths. After passing through a dispersive section, the energy modulation is converted into a density modulation at THz frequencies. This density-modulated beam will be used to generate narrow-band THz radiation using a coherent transition radiator inserted into the beam path. The central frequency of the THz radiation can be tuned by varying the wavelength of one of the two lasers or the energy chirp of the electron beam. The experiment is being performed at the NLCTA at SLAC, and will utilize the existing Echo-7 beamline, where echo-enabled harmonic generation (EEHG) was recently demonstrated.

TUPPC094	Experimental Observations of Large-amplitude Solitary Waves in Electron Beams	space-charge, electron, longitudinal-dynamics, gun	1377
	Y. Mo, B.L. Beaudoin, D.W. Feldman, I. Haber, R.A. Kishek, P.G. O'Shea UMD, College Park, Maryland, USA J.C.T. Thangaraj Fermilab, Batavia, USA
	Funding: Work funded by the US Dept. of Energy Offices of Fusion Energy Sciences and High Energy Physics and Fusion Energy Sciences, and by the Dept. of Defense Office of Naval Research. The longitudinal dynamics of space charge dominated beams plays an important role in particle accelerators and other applications such as heavy ion fusion and free electron lasers (FELs). All beams are space-charge dominated near the source. Furthermore, the longitudinal profile is not necessarily an ideal mathematical function. By means of experiments on the University of Maryland Electron Ring (UMER), we studied how a perturbation to the line charge density could affect the beam propagation. By varying the initial amplitude of the perturbation, we access nonlinear space charge physics. When starting with large-amplitude perturbations, we have observed, for the first time in charged particle beams, solitary waves for which the nonlinear steepening exactly balances the wave dispersion, leading to persistent waves that preserves their shape over a long distance. This paper presents the results of the soliton experiments, including systematic studies of the dependence of the soliton propagation on beam current, perturbation level and width. The data is compared with theory and simulation.

TUPPD023	RFQ LINAC Commissioning and Carbon⁴⁺ Acceleration for Ag¹⁵⁺ Acceleration via Direct Plasma Injection Scheme	ion, rfq, plasma, linac	1458
	T. Yamamoto, M. Washio RISE, Tokyo, Japan K. Kondo, M. Okamura, M. Sekine 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. High intensity, high charge state, various ion species and small emittance heavy ion beam is required for particle physics, medical uses, inertial fusion, and a simulator of space radiation. Direct Plasma Injection Scheme (DPIS), the way to make laser abrasion plasma developed in the past several years, is used for Heavy Ion beam Accerelation. High density plasma with an initial drift velocity will fly to the entrance of the Radio Frequency Quadropole (RFQ) LINAC; ions will be separated from plasma via high voltage and injected it to RFQ LINAC directly. After RFQ LINAC, ions accepted to the RF buckets are accelerated to a current of over 10mA. Until now, we tried a carbon target using the partial modulation rod of the RFQ LINAC, and succeeded in accelerating carbon⁴⁺, carbon⁵⁺, and carbon⁶⁺ non-bunched beam.* In this instance, we succeeded in commissioning of new full modulation RFQ rod designed for the charge mass ratio(q/A) 1/6. We tested the acceleration of carbon⁴⁺, and it could be catched by the RF bucket and accelerated. After this, we'll try accelerating carbon²⁺ (q/A=1/6) for demonstrating the feasibility of the Ag¹⁵⁺ ion accelerating. * T. Kanesue, M. Okamura, K. Kondo, J. Tamura, H. Kashiwagi, Z. Zhang, Drift distance survey in direct plasma injection scheme for high current beam production, Rev Sci Instrum. 2010 Feb;81(2):02B723

TUPPD034	Multi-bunch Beam Generation by Photo-cathode RF Gun for KEK-STF	cavity, gun, cathode, electron	1479
	M. Kuriki, S. Hosoda, H. Iijima HU/AdSM, Higashi-Hiroshima, Japan A. Ayaka Sokendai, Ibaraki, Japan H. Hayano, J. Urakawa, K. Watanabe KEK, Ibaraki, Japan G. Isoyama, R. Kato, K. Kawase ISIR, Osaka, Japan S. Kashiwagi Tohoku University, Research Center for Electron Photon Science, Sendai, Japan K. Sakaue RISE, Tokyo, Japan
	Funding: MEXT, Quantum beam project. KEK-STF is doing R&D of Super-Conducting (SC) accelerator technology for ILC (International Linear Collider), based on 1.3 GHz RF system. For STF and ILC, the pulse length is 1ms and the repetition is 5Hz. We developed a L-band Normal-Conducting RF gun designed by DESY to provide electron beam over such long pulse duration. For NC Photo-cathode RF gun, such high duty and long pulse operation is a challenging task, because the detuning by the heat load of cavity dissipation power is significant. The RF gun provides the electron pulse train to SC accelerator modules which will be operated at 31.5 MV/m gradient. Precise RF control is essential for SC accelerator because the beam loading and input RF power should be well ballanced for a stable operation. The beam test to demonstrate the stable opeation is very important for SC accelerator R&D. The system is also used to demonstrate high-flux quasi-monochromatic X-ray generation by inverse Compton scattering at KEK-STF. The experiment is carried out from April 2012 to November 2012 at KEK-STF. We report the latest status of the multi-bunch generation by the RF gun.

TUPPD037	Simulation Study of the Effect of the Proton Layer Thickness on TNSA	electron, plasma, proton, simulation	1488
	L. Lecz TEMF, TU Darmstadt, Darmstadt, Germany O. Boine-Frankenheim, V. Kornilov GSI, Darmstadt, Germany
	The LIGHT project is a collaboration of several laser and accelerator laboratories in Germany with the purpose to consolidate the theoretical, numerical and experimental investigations for the usage of laser accelerated ions in the conventional accelerators. The central facility is the PHELIX laser at GSI, Darmstadt, with a strong-field solenoid as a collimation and transport device. This contribution is devoted to the numerical investigation of the proton acceleration via the TNSA mechanism using 1D and 2D particle-in-cell electro-magnetic simulations. The phase-space distribution of the accelerated protons and co-moving electrons, which is necessary for further transport studies, is investigated for different parameters of the thin hydrogen-rich contamination layer on the rear target surface. Depending on the layer thickness the protons can be accelerated in different regimes, from the quasi-static acceleration for mono-layers up to the isothermal plasma expansion for thick layers.

TUPPD044	Conceptual Gas Jet as a Stripping Target for Charge Exchange Injection	target, injection, ion, proton	1500
	V.G. Dudnikov, C.M. Ankenbrandt Muons, Inc, Batavia, USA
	Stripping targets for charge exchange injection now uses thin carbon or Al2O3 foils. During long time injection for high intense beam accumulation by low current injection a foil life time can be compromised by overheating and alternative stripping targets need be developed. A pulsed supersonic gas jet was used as a stripping target in first realization of charge exchange injection with H⁻ ion energy 1.5 MeV and stationary gas jets are used as internal targets in experiments with super high vacuum. A stripper target thickness is proportional to the injection energy and for energy 1GeV should be ~0.3 mg/cm² of carbon. The pulsed gas target with such thickness acceptable for long time charge exchange injection can be produced with using of heavy hydrocarbon molecules used in the diffusion or booster vacuum pumps. Formation of the pulsed gas jet stripping targets will be considered.

TUPPD050	Investigation of Laser-cleaning Process on Lead Photocathodes	electron, cathode, photon, high-voltage	1515
	S.G. Schubert, R. Barday, T. Kamps, T. Quast, A. Varykhalov HZB, Berlin, Germany R. Nietubyć The Andrzej Soltan Institute for Nuclear Studies, Centre Świerk, Świerk/Otwock, Poland F. Siewert BESSY GmbH, Berlin, Germany J. Smedley BNL, Upton, Long Island, New York, USA G. Weinberg FHI, Berlin, Germany
	Funding: Work supported by Bundesministerium für Bildung und Forschung and Land Berlin. Metal photocathodes are widely used in electron injectors due to their stability and long life time; unfortunately they exhibit low quantum efficiency. Due to adsorption of contaminants the work function increases and thus the quantum efficiency is further reduced. In order to increase the quantum efficiency of our Pb cathode we performed a cleaning procedure by means of a high power excimer laser as suggested by Smedley. The process was studied on witness samples in a combined photo emission, SEM and quantum efficiency measurement study. Thin Lead films were arc-deposited on optical polished Mo-substrates. Before and after irradiation the sample was analyzed at 140 eV photon energy at a XPS/ARPES end station at the synchrotron radiation source Bessy II. We followed the change of the Pb 5d signals. In the initial situation we observed signals originating from metallic Pb and Pb in the oxidized state, respectively. Since the surface roughness is of concern for the injector performance it was examined before and after the irradiation procedure with white-light-interferometry and the surface morphology by means of SEM. J. Smedley et al, PRST-AB 11, 013502 (2008). ** Rao, T. et al., IPAC 2010, THPEC020 (2010).

TUPPD051	Operational Experience with the Nb/Pb SRF Photoelectron Gun	emittance, cathode, solenoid, cavity	1518
	T. Kamps, W. Anders, R. Barday, A. Jankowiak, J. Knobloch, O. Kugeler, A.N. Matveenko, A. Neumann, T. Quast, J. Rudolph, S.G. Schubert, J. Völker HZB, Berlin, Germany P. Kneisel JLAB, Newport News, Virginia, USA R. Nietubyć The Andrzej Soltan Institute for Nuclear Studies, Centre Świerk, Świerk/Otwock, Poland J.K. Sekutowicz DESY, Hamburg, Germany J. Smedley BNL, Upton, Long Island, New York, USA J. Teichert HZDR, Dresden, Germany V. Volkov BINP SB RAS, Novosibirsk, Russia I. Will MBI, Berlin, Germany
	SRF photoelectron guns offer the promise of high brightness, high average current beam production for the next generation of accelerator driven light sources such as free electron lasers, THz radiation sources or energy-recovery linac driven synchrotron radiation sources. In a first step a fully superconducting RF (SRF) photoelectron gun is under development by a collaboration between HZB, DESY, JLAB, BNL and NCBJ. The aim of the experiment is to understand and improve the performance of a Nb SRF gun cavity coated with a small metallic Pb cathode film on the cavity backplane. This paper describes the highlights from the commissioning and beam parameter measurements. The main focus is on lessons learned from operation of the SRF gun.

TUPPD052	A New Load Lock System for the Source of Polarized Electrons at ELSA	electron, vacuum, polarization, ion	1521
	D. Heiliger, W. Hillert, B. Neff ELSA, Bonn, Germany
	Funding: supported by DFG (SFB/TR16) Since 2000, an inverted source of polarized electrons at the electron stretcher accelerator ELSA routinely provides a pulsed beam with a current of 100 mA and a polarization degree of about 80%. One micro-second long pulses with 100 nC charge are produced by irradiating a GaAs strained-layer superlattice photocathode (8 mm in diameter) with laser light. Future accelerator operation requires a significantly higher beam intensity, which can be achieved by using photocathodes with sufficiently high quantum efficiency. Therefore, and in order to enhance the reliability and up time of the source, a new extreme high-vacuum (XHV) load lock system was installed and commissioned at the beginning of this year. It consists of three chambers: The activation chamber for heat cleaning of the photocathodes and activation with cesium and oxygen. The storage chamber in which up to five different types of photocathodes with various diameters of the emitting surface can be stored under XHV conditions. The loading chamber in which an atomic hydrogen source is used to remove any remaining surface oxidation. Additionally, tests of the photocathodes’ properties can be performed during operation.

TUPPD055	Characterization of ps-spaced Comb Beams at SPARC	simulation, linac, radiation, bunching	1527
	A. Mostacci URLS, Rome, Italy A. Bacci, A.R. Rossi Istituto Nazionale di Fisica Nucleare, Milano, Italy M. Bellaveglia, E. Chiadroni, G. Di Pirro, M. Ferrario, G. Gatti, C. Vaccarezza INFN/LNF, Frascati (Roma), Italy A. Cianchi Università di Roma II Tor Vergata, Roma, Italy C. Ronsivalle ENEA C.R. Frascati, Frascati (Roma), Italy
	SPARC in Frascati is a high brightness photo-injector used to explore advanced beam manipulation techniques. Sub-picosecond, high brightness electron bunch trains (the so called comb beam) can be generated illuminating the cathode of a RF photoinjector with a laser pulse train and via velocity bunching technique. In this paper different aspects of the physics of this advanced beam manipulation technique are discussed combining simulation and measurements. Beam dynamics numerical macroparticle simulations have been compared with the experimental results for model validation; they allow to gain insights on the beam evolution highlighting several aspects which can not be measured. In particular, we focus on the train evolution in the linac sections and in the dog-leg line up to the THz station and on the effective rms length of the single pulses within the train when it becomes shorter than the resolution.

TUPPD056	Development of a Photo-injector Laser System for KEK ERL Test Accelerator	cavity, cathode, controls, alignment	1530
	Y. Honda KEK, Ibaraki, Japan
	As a test accelerator for future light source, Compact Energy Recovery Linac has been constructed in KEK. For its photo-injector, we have been developing a laser system. It requires high repetition rate and high average power at a visible wavelength. Development of an high power fiber amplifier and high efficiency wavelength conversion system utilizing an optical cavity will be reported.

TUPPD057	High Charge Low Emittance RF Gun for SuperKEKB	gun, cathode, emittance, injection	1533
	T. Natsui, Y. Ogawa, M. Yoshida, X. Zhou KEK, Ibaraki, Japan
	We are developing a new RF gun for SuperKEKB. We are upgrading KEKB to SuperKEKB now. High charge low emittance electron and positron beams are required for SuperKEKB. We will generate 7.0 GeV electron beam at 5 nC 20 mm-mrad by J-linac. In this linac, a photo cathode S-band RF gun will be used as the electron beam source. For this reason, we are developing an advanced RF gun. Now, we are testing a Disk and Washer (DAW) type RF gun. Its photo cathode material is LaB6. Normally, LaB6 is used as a thermionic cathode, but it is suitable for　long-life photo cathode operation. This gun has a strong focusing field at the cathode and the acceleration field distribution also has a focusing effect. We will obtain 3.2 MeV beam energy with the gun. The design of RF gun and experimental results will be shown.

TUPPD061	High-Power RF Test of an RF-Gun for PAL-XFEL	gun, emittance, electron, injection	1539
	J.H. Hong, J.H. Han, H.-S. Kang, C. Kim, S.H. Kim, C.-K. Min, S.S. Park, S.J. Park, Y.J. Park PAL, Pohang, Kyungbuk, Republic of Korea M.S. Chae, I.S. Ko, Y.W. Parc POSTECH, Pohang, Kyungbuk, Republic of Korea
	A photocathode RF-gun for the X-ray free electron laser (XFEL) at the Pohang Accelerator Laboratory (PAL) has been fabricated and tested at PAL. This RF-gun is based on a 1.6-cell cavity with dual-feed waveguide ports and two pumping ports. The RF gun was designed by PAL and POSTECH. The RF-gun has been successfully tested with a cathode electric field gradient up to 126MV/m at a repetition rate of 30 Hz. This paper reports the recent results on the beam test of the RF-gun with high power RF at the gun test facility. We present and discuss the measurements of the basic beam parameters such as charge, energy, energy spread, and transverse emittance.

TUPPD062	The Source of Emittance Dilution and photoemission tunneling effect in Photocathode RF Guns	cathode, emittance, cavity, simulation	1542
	V. Volkov BINP SB RAS, Novosibirsk, Russia R. Barday, T. Kamps, J. Knobloch, A.N. Matveenko, S.G. Schubert, J. Völker HZB, Berlin, Germany J.K. Sekutowicz DESY, Hamburg, Germany
	Funding: Work supported by Bundesministerium für Bildung und Forschung, Land Berlin, and grants of Helmholtz Association VH-NG-636 and HRJRG-214. Experimental data on HoBiCaT SRF photoinjector give an emittance which is much larger than the predicted thermal emittance. Modeling of photocathode RF gun beams with the different imperfections of experimental setup (alignment errors, inhomogeneity of quantum efficiency and laser power distributions on the cathode) is given. The main reason for the beam emittance dilution is photocathode field imperfections induced by field emitters that change the local electric field. Some field models of such photocathodes are tested in the simulations. The dependence of photocathode beam currents on the surface electric field was measured with the HoBiCaT SRF Photoinjector. The dependence can be explained by the tunneling effect described by Fowler-Nordheim like equation and is difficult to explain by usually applying Schottky effect.

TUPPD066	Lifetime Studies of Cs2Te Cathodes at the PHIN RF Photoinjector at CERN	vacuum, cathode, gun, beam-losses	1554
	C. Heßler, E. Chevallay, M. Divall Csatari, S. Döbert, V. Fedosseev CERN, Geneva, Switzerland
	The PHIN photoinjector has been developed to study the feasibility of a photoinjector option for the CLIC (Compact LInear Collider) drive beam as an alternative to the baseline design, using a thermionic gun. The CLIC drive beam requires a high charge of 8.4 nC per bunch in 0.14 ms long trains, with 500 MHz bunch spacing and 50 Hz macro pulse repetition rate, which corresponds to a total charge per macro pulse of 0.59 mC. This means unusually high peak and average currents for photoinjectors and is challenging with respect to the cathode lifetime. In this paper detailed studies of the lifetime of Cs2Te cathodes, produced by the co-evaporation technique, with respect to bunch charge, train length and vacuum level are presented. Furthermore, the impact of the train length and bunch charge on the vacuum level will be discussed and steps to extend the lifetime will be outlined.

TUPPD067	Experimental Facility for Measuring the Electron Energy Distribution from Photocathodes	electron, cathode, vacuum, brightness	1557
	L.B. Jones, R.J. Cash, B.D. Fell, J.W. McKenzie, K.J. Middleman, B.L. Militsyn STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom H.E. Scheibler, A.S. Terekhov ISP, Novosibirsk, Russia
	ASTeC have spent several years developing a GaAs Photocathode Preparation Facility (PPF) which routinely produces cathodes with quantum efficiencies (Q.E.) up to 20% at 635 nm. The goal is to use these cathodes in high-average-current high-brightness injectors for particle accelerators. Electron injector brightness is driven by photocathode emittance, and brightness will be increased significantly by reducing the longitudinal and transverse energy spread. We are constructing an experimental system for measurement of the horizontal and transverse energy spreads at room and LN₂-temperature which accepts photocathodes from the PPF. The sample will be illuminated by a small, variable-wavelength light spot. The beam image will be projected onto a detector comprised of 3 grids which act as an energy filter, a micro-channel plate and a phosphor screen. A low-noise CCD camera will capture screen images, and the electron distribution and energy spread will be extracted through analysis of these images as a function of the grid potentials. The system will include a leak valve to progressively degrade the cathode, and thus allow its properties to be measured as a function of Q.E. Proc IPAC ’11, THPC129 (2011).

TUPPD068	Design of the Production and Measurement of Ultra-Short Electron Bunches from an S-band RF Photoinjector	cavity, gun, dipole, electron	1560
	J.W. McKenzie, D. Angal-Kalinin, J.K. Jones, B.L. Militsyn STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	The Electron Beam Test Facility (EBTF) is planned for installation in late 2012 at Daresbury Laboratory. An S-band RF photoinjector provides ultrashort, low emittance electron bunches up to 6 MeV. A suite of diagnostics has been designed to fully characterise the bunches. A particular focus has been on producing and measuring bunch lengths less than 100 fs. This can be achieved with a multi-cell standing wave S-band transverse deflecting cavity. Operating such a cavity with low energy electrons provides certain challenges which are discussed in this paper with respect to beam dynamic simulations.

TUPPD069	Schottky-Enabled Photoemission and Dark Current Measurements - Toward an Alternate Approach to Fowler-Nordheim Plot Analysis	gun, site, photon, cathode	1563
	E.E. Wisniewski, W. Gai, J.G. Power ANL, Argonne, USA H. Chen, Y.-C. Du, Hua, J.F. Hua, W.-H. Huang, C.-X. Tang, L.X. Yan, Y. You TUB, Beijing, People's Republic of China A. Grudiev, W. Wuensch CERN, Geneva, Switzerland E.E. Wisniewski Illinois Institute of Technology, Chicago, Illinois, USA
	Field-emitted dark current, a major gradient-limiting factor in RF cavities, is usually analyzed via Fowler-Nordheim (FN) plots. Traditionally, field emission is attributed to geometrical perturbations on the bulk surface whose field enhancement factor (beta) and the emitting area (A) can be extracted from the FN plot. Field enhancement factors extracted in this way are typically much too high (1 to 2 orders of magnitude) to be explainable by either the geometric projection model applied to the measured surface roughness or by field enhancement factors extracted from Schottky-enabled photoemission measurements. We compare traditional analysis of FN plots to an alternate approach employing local work function variation. This is illustrated by comparative analysis of recent dark current and Schottky-enabled photoemission data taken at Tsinghua S-band RF gun. We conclude by describing a possible experimental plan for discrimination of variation of local work function vs. local field enhancement.

TUPPD076	Photocathode Studies for the SPEAR3 Injector RF Gun	cathode, linac, gun, klystron	1575
	S. Park, W.J. Corbett, S.M. Gierman, J.R. Maldonado SLAC, Menlo Park, California, USA
	Funding: Work supported by U.S. Department of Energy Contract DE-AC03- 76SF00515 and Office of Basic Energy Sciences, Division of Chemical Sciences. The electron gun for the SPEAR3 injector operates with a warm thermionic dispenser cathode immersed in a 1.5-cell RF structure. At each injection cycle the gun accelerates several thousand electron bunches up to ~3 MeV during a 2.5us rf pulse. The individual bunches are then compressed by an alpha magnet and a traveling-wave chopper selects 3-5 bunches so they don’t cause beam loading to the linac, where the accelerated bunches reach 120 MeV for subsequent capture in a single booster synchrotron bucket. Tests are underway to operate the dispenser cathode as a cold electron photo-emitter driven by an external laser system. Eventually, without the copper, this will enable multi-bunch injections to the Booster and SPEAR3. In parallel, tests are underway to evaluate quantum efficiency and beam emittance for a beam emitted from a CsBr photocathode with ns- and ps-pulses of UV laser light. In this paper we report on both the cold cathode electron gun operation studies for SPEAR3 and the CsBr research aimed at developing advanced cathode materials for future applications.

TUPPD079	Design of an L-Band RF Photoinjector for the Idaho Accelerator Center 44 MeV Linac	linac, emittance, gun, solenoid	1584
	M. Titberidze, A.W. Hunt, D.P. Wells IAC, Pocatello, IDAHO, USA Y. Kim ISU, Pocatello, Idaho, USA
	At the Idaho Accelerator Center (IAC) of Idaho State University, we have been operating a 44 MeV L-band RF (1300 MHz) linear accelerator (LINAC) for various user applications such as medical isotope production, Laser Compton Scattering (LCS), positron annihilation energy spectroscopy, and photo fission. But the LINAC is not optimized properly to supply high quality electron beam for those experiments due to limitations of an existing 85 kV thermionic DC gun. In the near future, we are planning to use the L-band LINAC for new user applications such as Accelerator Driven subcritical nuclear reactor System (ADS), photon tagging facility, Ultrafast Electron Diffraction (UED) facility, and high power coherent Terahertz light source facility. Therefore, recently, we have been studying a future upgrade of the L-band LINAC with an RF photoinjector using ASTRA code. In this paper, we describe ASTRA simulation results and a new layout of the L-band LINAC, which is based on an L-band 1.5 cell RF photoinjector. Then, we describe its expected performance for two different single bunch charges (1 nC and 5 nC).

TUPPD080	Design of Ultrafast High-Brightness Electron Source	cathode, electron, gun, brightness	1587
	J.H. Park, H. Bluem, J. Rathke, T. Schultheiss, A.M.M. Todd AES, Princeton, New Jersey, USA
	Funding: This work was supported by the U.S. Department of Energy, under Contract No. DE-SC0006210. Generation and preservation of ultrafast electron beams is one of the major challenges in accelerator R&D. Space charge forces play a fundamental role in emittance dilution and bunch lengthening for all high brightness beams. In order to generate and preserve the ultrafast high-brightness electron beam, transverse and longitudinal space charge effects have to be considered. Several approaches to achieving ultra-short bunches have been explored such as velocity bunching and magnetic compression. However, each option suffers drawbacks in achieving a compact ultrafast high-brightness source. We present an alternative scheme to achieve an ultrafast high-brightness electron beam using a radial bunch compression technique in an x-band photocathode RF electron gun. By compensating the path length difference with a curved cathode and using an extremely high acceleration gradient (greater than 200 MV/m), we seek to deliver 100 pC, 100 fsec bunches.

TUPPP005	LUNEX5: A French FEL Test Facility Light Source Proposal	FEL, emittance, electron, undulator	1611
	A. Loulergue, C. Benabderrahmane, M. Bessière, P. Betinelli-Deck, F. Bouvet, A. Buteau, L. Cassinari, M.-E. Couprie, J. Daillant, J.-C. Denard, P. Eymard, B. Gagey, C. Herbeaux, M. Labat, A. Lestrade, P. Marchand, J.L. Marlats, C. Miron, P. Morin, A. Nadji, F. Polack, J.B. Pruvost, F. Ribeiro, J.P. Ricaud, P. Roy SOLEIL, Gif-sur-Yvette, France S. Bielawski, C. Evain, C. Szwaj PhLAM/CERCLA, Villeneuve d'Ascq Cedex, France B. Carré CEA/DSM/DRECAM/SPAM, Gif-sur-Yvette, France G. Devanz, M. Luong CEA/DSM/IRFU, France L. Farvacque, G. Lebec ESRF, Grenoble, France G. Lambert, A. Lifschitz, V. Malka, A. Rousse LOA, Palaiseau, France M. Le Parquier CERLA, Villeneuve d'Ascq, France J. Lüning CCPMR, Paris, France R. Roux LAL, Orsay, France
	LUNEX5 is a new synchrotron FEL source project aiming at delivering short and coherent X-ray pulses to probe ultrafast phenomena at the femto-second scale, to investigate extremely low density samples as well as to image individual nm scale objects. The proposed machine layout is based on a 400 MeV super-conducting Conventional Linear Accelerator (CLA) mainly composed of 2 XFEL type cryo-modules together with a normal-conducting high brightness photo RF gun. This present mature and reliable technology is able to deliver high quality electron bunches up to few kHz suitable for user experiments. Further more, the last decade improvement in synchronization and stability offer a fertile land to explore the different and innovative seeded FEL operations aiming at producing higher coherence and energetic X-rays for the pilot user full benefits. In parallel of the CLA branch, the very promising and highly innovative Laser Wake-Field Accelerator (LWFA) able to produce very short electron bunches in the range of the femto-second and high peak current up to few GeV is foreseen as a FEL bench test using the same undulator lines.

TUPPP008	Recent Results From the Short-Pulse Facility at the DELTA Storage Ring	radiation, electron, undulator, synchrotron	1617
	A. Schick, M. Bakr, H. Huck, M. Höner, S. Khan, R. Molo, A. Nowaczyk, P. Ungelenk, M. Zeinalzadeh DELTA, Dortmund, Germany
	Funding: Work supported by DFG, BMBF and by the Federal State NRW. At the 1.5 GeV synchrotron light source DELTA, operated by the TU Dortmund University, a new facility for ultrashort pulses in the VUV and THz regime is currently under commissioning. Here, the interaction of an intense, ultrashort laser pulse, co-propagating with the electrons in an optical klystron, leads to coherent synchrotron radiation at harmonics of the incident laser wavelength. The aim of the present commissioning steps is to extend the emitted wavelength down to about 50 nm, enabling femtosecond-resolved pump-probe experiments in the VUV regime. Other issues include increasing the photon flux by optimizing the laser-electron interaction and improving the stability and ease of operation of the source.

TUPPP012	Optimization of the Beam Optical Parameters of the Linac-based Terahertz Source FLUTE	gun, space-charge, linac, simulation	1629
	S. Naknaimueang, E. Huttel, A.-S. Müller, M.J. Nasse, R. Rossmanith, M. Schuh, M. Schwarz, P. Wesolowski KIT, Karlsruhe, Germany M.T. Schmelling MPI-K, Heidelberg, Germany
	Funding: Karlsruher Institut für Technologie. FLUTE is a compact accelerator (consisting of a 7 MeV laser gun, a 50 MeV linac, and bunch compressors) under construction at KIT in Karlsruhe for producing coherent THz radiation. The programs ASTRA and CSRtrack were used to optimize the beam parameters. The aim was to minimize the bunch length used in various THz experiments, with bunch charges between 100 pC and 3 nC. It was calculated that the bunch length after compression depends both on the bunch current and the transverse beam size. The transverse beam size depends on the laser spot size at the cathode of the 7 MeV laser gun. Further simulations showed that a larger beam size reduces the efficiency of the compressor. This problem is cured by focusing elements with a focusing strength depending on the space charge after the gun and integrated into the various compressors layouts under study (four magnets, two magnets and quadrupoles, etc.). The results of these calculations are presented in this paper.

TUPPP027	Subpicosecond Laser Slicing X-Ray Source for Time-resolved Research at TPS	wiggler, emittance, photon, lattice	1671
	W.K. Lau, M.C. Chou, C.-S. Hwang, A.P. Lee, Y.-C. Liu, G.-H. Luo NSRRC, Hsinchu, Taiwan N.Y. Huang NTHU, Hsinchu, Taiwan
	The 3 GeV Taiwan Photon Source (TPS) under construction at NSRRC should be ready for user run in 2014. X-ray users in many research areas will then be benefited. However, there has been a growing interest in ultrafast time-resolved research in the island. The feasibility of using ultrafast laser for electron-beam slicing at TPS to produce sub-picosecond x-ray pulses is being investigated recently. The design and layout of a laser slicing scheme with W250 wiggler as the energy modulator in a 7 m medium straight section and EPU48 and IU22 radiators in other straight sections will be presented. It will offer the unique opportunity to gain experience in experimental techniques needed for FEL science.

TUPPP048	Increasing the Spectral Range of the CLIO Infrared FEL User Facility by Reducing Diffraction Losses	undulator, vacuum, FEL, simulation	1709
	J.-M. Ortega, G. Perilhous, R. Prazeres LCP/CLIO, Orsay, Cedex, France H.B. Abualrob, P. Berteaud, L. Chapuis, M.-E. Couprie, T.K. El Ajjouri, F. Marteau, J. Vétéran SOLEIL, Gif-sur-Yvette, France J.P. Berthet, F. Glotin CLIO/ELISE/LCP, Orsay, France
	Funding: CNRS/RTRA The infrared free-electron laser offers a large tunability since the FEL gain remains high throughout the infrared spectral range, and the reflectivity of metal mirrors remains also close to 1. The main limitation comes from the diffraction of the optical beam due to the finite size of the vacuum chamber of the undulator. At CLIO, we have obtained previously* an FEL tunable from 3 to 150 μm by operating the accelerator between 50 and 14 MeV. However, we found that a phenomenon of “power gaps“ is observed in far-infrared : the laser power falls down to zero at some particular wavelengths, whatever the beam adjustments are. We showed that this effect is related to to the waveguiding effect of the vacuum chamber leading to different losses and power outcoupling at different wavelengths*. To alleviate this effect we have designed a new undulator allowing to use a larger vacuum chamber without reducing the spectral tunability and agility of the FEL. From simulations, a large increase of available power is expected in far-infrared. The new undulator has been installed and its performances and first FEL measurement in far-infrared will be presented J.M. Ortega, F. Glotin, R. Prazeres Infrared Physics and Technology, 49, 133 (2006) ** R. Prazeres, F. Glotin, J.-M. Ortega Phys. Rev. STAB12, 010701 (2009)

TUPPP050	FEL Performances of the French LUNEX5 Project	FEL, electron, bunching, undulator	1712
	C. Evain, S. Bielawski PhLAM/CERCLA, Villeneuve d'Ascq Cedex, France C. Benabderrahmane, M.-E. Couprie, C. Evain, M. Labat, A. Loulergue SOLEIL, Gif-sur-Yvette, France G. Lambert, A. Lifschitz, V. Malka LOA, Palaiseau, France
	LUNEX5 is a french FEL test facility project based on two types of accelerators: a 400 MeV Conventional Linear Accelerator (CLA) and a Laser WakeField Accelerator (LWFA). The FEL performances will be presented at 20 nm and at 12 nm, wavelengths of interest for the pilot experiments. Results are obtained with GENESIS simulations in time-dependent mode. With the CLA, we compare different seeded schemes as EEHG scheme (Echo Enabled Harmonic Generation) or HGHG scheme (High Gain Harmonic Generation) using HHG source (High Harmonic in Gaz). In parallel, LWFA FEL performances will be presented as a function of the electron bunch characteristics, in particular the bunch length and the energy-spread. The transport of the LWFA output beams into undulators which is found to be a critical issue will be also discussed.

TUPPP052	Status of FLASH	FEL, electron, photon, undulator	1715
	K. Honkavaara, B. Faatz, J. Feldhaus, S. Schreiber, R. Treusch, M. Vogt DESY, Hamburg, Germany
	FLASH at DESY (Hamburg, Germany) is a free-electron laser user facility driven by a superconducting 1.25 GeV linac based on TESLA technology. During the 3rd user period from September 2010 to September 2011, totally 3740 hours of FEL radiation has been delivered to FEL experiments at more than 30 different wavelengths between 4.7 nm and 45 nm. In addition, beam time has been dedicated to general accelerator physics studies and developments related to the future projects like the European XFEL and the International Linear Collider. After a 3.5 months shutdown in autumn 2011 due to civil construction for a second undulator beamline - FLASH2 - and a following commissioning and study period, 2012 is mainly dedicated to FEL user experiments. This paper summarizes the operation status of the FLASH facility and gives also a short review of the accelerator studies carried out in 2011 and early 2012. The mid-term plans including FLASH2 are presented as well.

TUPPP053	Investigations on the Optimum Accelerator Parameters for the Ultra-Short Bunch Operation of the Free-Electron Laser in Hamburg (FLASH)	emittance, electron, simulation, space-charge	1718
	M. Rehders, J. Rönsch-Schulenburg, J. Roßbach Uni HH, Hamburg, Germany T. Limberg, H. Schlarb, S. Schreiber DESY, Hamburg, Germany
	Funding: The project is supported by the Federal Ministry of Education and Research of Germany (BMBF) under contract No. 05K10GU2 and FSP301. In order to produce the shortest possible radiation pulses using Free Electron Lasers like FLASH, various possibilities have been proposed during the last decade. Probably the most robust method is the generation of electron bunches that in the most extreme case are as short as a single longitudinal optical mode of the SASE (Self-Amplified Spontaneous Emission) radiation. For FLASH this means that the bunch length has to be a few fs only. As a consequence, very low bunch charges (in the order of 20 pC) have to be used. To achieve these extremely short bunch lengths, a new photo-injector laser has been installed, which allows for the generation of shorter electron bunches right at the cathode. Simulations of the electron bunches and their six-dimensional phase-space distribution have been performed to investigate the optimum accelerator parameters during injection and to determine how to realize them. First results are discussed in this contribution.

TUPPP056	Study of the Energy Chirp Effects on Seeded FEL Schemes at SDUV-FEL	FEL, electron, radiation, undulator	1724
	C. Feng, D. Wang, Z.T. Zhao SINAP, Shanghai, People's Republic of China
	Seeded free-electron laser (FEL) schemes hold great promise for generation of high brilliant radiation with a narrow bandwidth. Analysis with the idealized electron beam with constant current and energy indicate that both the high-gain harmonic generation (HGHG) and the echo-enabled harmonic generation (EEHG) can produce Fourier-transform limited radiation pulses. However, residual energy variations due to nonlinearity of the accelerator or energy modulations due to microbunching instability will be unavoidable and may broaden the bandwidth of the seeded FEL. In this paper, we study the energy chirp effects on both the HGHG and EEHG schemes. Analytic and simulation calculations are presented and compared with the experimental data. Results show that the coherence properties of the EEHG FEL may not be degraded by the energy chirp when properly choosing the parameters of the dispersion sections.

TUPPP057	Design of a Wavelength Continuously Tunable Ultraviolet Coherent Light Source	FEL, radiation, simulation, undulator	1727
	T. Zhang, D. Wang, Z.T. Zhao SINAP, Shanghai, People's Republic of China X.M. Yang DICP, Dalian, People's Republic of China
	Funding: Work supported by National Natural Science Foundation of China (Grant No. 11075199) Dalian Coherent Light Source (DCL) is a proposed FEL-based novel light source user facility, will be located in Dalian city, China. DCL will mainly servers on the field of molecular reaction dynamics, ultra-fast physical chemistry experiments, etc. Running on the High-Gain-Harmonic-Generation (HGHG) FEL mode, DCL is expected to cover the FEL wavelength from 50 nm to 150 nm, with the help of continuously tuning Optical Parametric Amplification (OPA) seed laser system, which wavelength can be varied between 240 nm and 360 nm. Numerical simulation shows that the FEL pulse energy of DCL can surpass 100 μJ, at the whole full range wavelength with the undulator tapering technology, and the photon number can be up to 10¹³ per pulse, which is sufficient for user experiments.

TUPPP060	Injector Design for PAL-XFEL Project	gun, emittance, solenoid, cathode	1732
	J.H. Han, M.S. Chae, J.H. Hong, I. Hwang, H.-S. Kang, I.S. Ko, S.J. Park PAL, Pohang, Kyungbuk, Republic of Korea
	Funding: The Ministry of Education, Science and Technology of the Korean Government The PAL-XFEL project has the baseline specification of FEL radiation down to 0.1 nm with a 10 GeV S-band normal conducting linac. To fulfill the requirement of the beam parameter, the S-band photoinjector was designed. Numerical optimizations for nominal and low charge operations are presented.

TUPPP064	Microbunching Instability Studies in SwissFEL	simulation, booster, FEL, linac	1744
	S. Bettoni, B. Beutner Paul Scherrer Institut, Villigen, Switzerland V.A. Goryashko NASU/IRE, Kharkov, Ukraine
	Shot noise or an initial intensity modulation in the beam pulse may have a strong effect in the FEL linacs and also severely degrade the machine performances in terms of FEL performances. In this paper we present the simulations done to study this effect in SwissFEL, the future free electron laser under design at Paul Scherrer Institute. In particular we calculated the gain of the microbunching instability in the low and high energy part and we performed start-to-end simulations using as initial distribution something as close as possible to the laser profile measured at the SwissFEL injector test facility. We finally present the preliminary calculations to estimate the effect of the laser heater to mitigate this effect.

TUPPP065	Progress Report on the SwissFEL Injector Test Facility	emittance, quadrupole, optics, dipole	1747
	T. Schietinger, M. Aiba, S. Bettoni, B. Beutner, M. Csatari, K. Doshekenov, Y.-C. Du, M.W. Guetg, C.P. Hauri, R. Ischebeck, F. Le Pimpec, N. Milas, G.L. Orlandi, M. Pedrozzi, P. Peier, E. Prat, S. Reiche, B. Smit, A. Trisorio, C. Vicario Paul Scherrer Institut, Villigen, Switzerland
	The SwissFEL injector test facility at the Paul Scherrer Institute is the principal test bed and demonstration plant for the SwissFEL project, which aims at realizing a hard-X-ray Free Electron Laser by 2017. The RF photoinjector facility has been in operation since 2010 and has recently reached its design energy of 250 MeV. A newly installed movable magnetic chicane allows longitudinal bunch compression studies. We report on the first experience with the bunch compressor and present the latest results of projected and slice emittance measurements.
	Poster TUPPP065 [1.801 MB]

TUPPP066	CLARA - A Proposed New FEL Test Facility for the UK	FEL, electron, undulator, diagnostics	1750
	J.A. Clarke, D. Angal-Kalinin, D.J. Dunning, S.P. Jamison, J.K. Jones, J.W. McKenzie, B.L. Militsyn, N. Thompson, P.H. Williams STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom R. Bartolini JAI, Oxford, United Kingdom I.P.S. Martin Diamond, Oxfordshire, United Kingdom
	A new single pass national FEL test facility, CLARA, is proposed to be constructed at Daresbury Laboratory in the UK. The aim of CLARA is to develop a normal conducting test accelerator able to generate longitudinally and transversely bright electron bunches and to use these bunches in the experimental production of stable, synchronized, ultra short photon pulses of coherent light from a single pass FEL with techniques directly applicable to the future generation of light source facilities. In addition the facility will be an ideal test bed for demonstrating innovative technologies such as high repetition rate normal conducting RF linacs and advanced undulator designs. This paper will describe the design of CLARA, pointing out the flexible features that will be incorporated to allow multiple novel FEL schemes to be proven.

TUPPP070	Next Generation Light Source R&D and Design Studies at LBNL	FEL, linac, electron, gun	1762
	J.N. Corlett, B. Austin, K.M. Baptiste, D.L. Bowring, J.M. Byrd, S. De Santis, P. Denes, R.J. Donahue, L.R. Doolittle, P. Emma, D. Filippetto, G. Huang, T. Koettig, S. Kwiatkowski, D. Li, T.P. Lou, H. Nishimura, H.A. Padmore, C. F. Papadopoulos, G.C. Pappas, G. Penn, M. Placidi, S. Prestemon, D. Prosnitz, J. Qiang, A. Ratti, M.W. Reinsch, D. Robin, F. Sannibale, D. Schlueter, R.W. Schoenlein, J.W. Staples, C. Steier, C. Sun, T. Vecchione, M. Venturini, W. Wan, R.P. Wells, R.B. Wilcox, J.S. Wurtele LBNL, Berkeley, California, USA
	Funding: Work supported by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. LBNL is developing design concepts for a multi-beamline soft x-ray FEL array powered by a superconducting linear accelerator, operating with a high bunch repetition rate of approximately one MHz. The cw superconducting linear accelerator is supplied by an injector based on a high-brightness, high-repetition-rate photocathode electron gun. Electron bunches are distributed from the linac to the array of independently configurable FEL beamlines with nominal bunch rates up to 100 kHz in each FEL, and with even pulse spacing. Individual FELs may be configured for different modes of operation, and each may produce high peak and average brightness x-rays with a flexible pulse format, and with pulse durations ranging from sub-femtoseconds to hundreds of femtoseconds. In this paper we describe conceptual design studies and optimizations. We describe recent developments in the design and performance parameters, and progress in R&D activities.

TUPPP074	Beam Dynamics Studies of a High-repetition Rate Linac Driver for a 4th-generation Light Source	FEL, emittance, simulation, linac	1771
	M. Venturini, J.N. Corlett, P. Emma, C. F. Papadopoulos, G. Penn, M. Placidi, J. Qiang, M.W. Reinsch, F. Sannibale, C. Steier, R.P. Wells LBNL, Berkeley, California, USA
	We present progress toward the design of a super-conducting linac driver of a high repetition rate FEL-based soft x-ray light source. The machine is intended to accept beams generated by the APEX* photocathode gun, operating in the MHz range, and deliver them to an array of SASE and seeded FEL beamlines. After reviewing the beam-dynamics considerations that are informing specific lattice choices we discuss the expected performance of the proposed machine design and its ability to meet the desired FEL specifications. We consider the merit of possible alternate designs (e.g., a one-stage compressor vs. a two-stage compressor) and the trade-offs between competing demands on the beam attributes (e.g., high peak current vs. acceptable energy spread). * F. Sannibale et al., this conference.

TUPPP086	A Synchronized FIR/VUV Light Source at Jefferson Lab	FEL, wiggler, electron, coupling	1789
	S.V. Benson, D. Douglas, G. Neil, M.D. Shinn, G.P. Williams JLAB, Newport News, Virginia, USA
	Funding: This work was supported by U.S. DOE Contract No. DE-AC05-84-ER40150, the Air Force Office of Scientific Research, DOE Basic Energy Sciences. We describe a dual FEL configuration on the UV Demo FEL at Jefferson Lab that would allow simultaneous lasing at THz and UV wavelengths. The THz source would be an FEL oscillator with a short wiggler providing diffraction-limited pulses with pulse energy exceeding 50 microJoules. The THz source would use the exhaust beam from a UVFEL. The coherent harmonics in the VUV from the UVFEL are outcoupled through a hole. The THz source uses a shorter resonator with either hole or edge coupling to provide very high power THz pulses. Simulations indicate excellent spectral brightness in the THz region with over 100 W/cm^-1 output.

TUPPP090	Studies of Controlled Laser-induced Microbunching Instability at Source Development Laboratory	electron, linac, radiation, space-charge	1798
	S. Seletskiy, B. Podobedov, Y. Shen, X. Yang BNL, Upton, Long Island, New York, USA
	We present the studies of controlled microbunching intentionally induced on the beam by the photocathode laser with modulated longitudinal profile. Varying the depth and frequency of longitudinal modulation of the laser pulse allowed us to observe the development of microbunching instability at BNL Source Development Laboratory (SDL) in the controlled environment. That allowed us to benchmark the model of the microbunching gain for the first time. In addition to that, we demonstrated for the first time a constructive work of a so-called longitudinal space charge amplifier, which in case under consideration can be utilized for enhancement of linac-based sources of THz radiation.

TUPPP093	General Results on the Nature of FEL Amplification	electron, FEL, free-electron-laser, wiggler	1804
	S.D. Webb Tech-X, Boulder, Colorado, USA V. Litvinenko, G. Wang BNL, Upton, Long Island, New York, USA
	Free-electron lasers are increasingly important tools for the material and biological sciences, and although numerical and analytical theory is extensive, a fundamental question about the nature of the FEL growing modes has remained unanswered. In this proceeding, we present results of a topological nature concerning the number of amplifying solutions to the 1-dimensional FEL equations as related to the energy distribution of the electron bunches.

TUPPR012	Polarized Positron Source with a Compton Multiple Interaction Point Line	positron, electron, simulation, linac	1834
	I. Chaikovska, O. Dadoun, P. Lepercq, A. Variola LAL, Orsay, France R. Chehab IN2P3 IPNL, Villeurbanne, France
	Positron sources are critical components of the future lepton colliders projects. This is essentially due to the high luminosity required, orders of magnitude higher than existing ones. In addition, polarization of the positron beam rather expands the physics research potential of the machine by increasing the precision of the measurements and enhancing certain types of interactions. In this framework, the Compton sources for polarized positron production are taken into account where the high energy gamma rays are produced by the Compton scattering and subsequently converted in the polarized electron-positron pairs in a target. The Compton multiple IP line is proposed as one of the solutions to increase the number of captured positrons. This allows a significant increase in the emitted gamma ray flux impinging on the target. The gamma ray production with the Compton multiple IPs line is simulated and used for polarized positron generation. Later, a capture section based on an adiabatic matching device followed by a pre-injector linac is simulated to capture and accelerate the positron beam. The results obtained are presented and discussed.

WEXB01	Recent Advances and New Techniques in Visualization of Ultra-short Relativistic Electron Bunches	radiation, electron, FEL, RF-structure	2091
	D. Xiang SLAC, Menlo Park, California, USA
	Funding: Work supported by U.S. DOE under Contract No. DE-AC02-76SF00515. This talk will address advances in the measurement of ultra-short relativistic bunches at femtosecond frontier in high-energy x-ray free-electron lasers (FELs). In general, this presentation will discuss several recently proposed novel techniques (i.e. mapping z exactly to delta * and x , optical oscilloscope , etc.) that are capable of breaking the femtosecond time barrier in measurements of ultrashort bunches. In particular, this presentation will report on the all-optical, time-resolved method to probe beam longitudinal phase space with femtosecond time scale and 10^-5 energy scale resolution *. The simultaneous measurement of temporal profile and beam slice energy spread after the FEL interaction is also shown to reveal the time-dependent x-ray radiation profile **. Z. Huang et al., PRSTAB 13, 092801. D. Xiang, Y. Ding, PRSTAB 13, 094001. * G. Andonian et al., PRSTAB 14, 072802. ** D. Xiang et al., PRSTAB 14, 112801. *** Y. Ding et al., FEL11.
	Slides WEXB01 [6.873 MB]

WEYB01	The SPring-8 Angstrom Compact Free Electron Laser (SACLA)	electron, emittance, undulator, FEL	2106
	H. Tanaka RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
	Commissioning of the world's first compact X-ray FEL facility named SPring-8 Angstrom Compact free electron LAser (SACLA) began in the Spring of 2011 and soon demonstrated lasing at a wavelength of 0.12nm. In the autumn of 2011 laser intensity reached sub mJ/pulse in the wavelengths ranging from 0.1 to 0.3 nm. The laser power saturation was also achieved at around or longer than 0.1 nm. The official user operation will start from March 2012. This presentation will cover innovative design aspects of the SACLA construction project, events leading to key milestones in the commissioning process, a review of the present status and perspectives on future upgrades.
	Slides WEYB01 [13.170 MB]

WEOBB01	Measurement of the Local Energy Spread of Electron Beam at SDUV-FEL	electron, FEL, bunching, radiation	2143
	C. Feng, J.H. Chen, H.X. Deng, T. Lan, B. Liu, D. Wang, X. Wang, M. Zhang, T. Zhang, Z.T. Zhao SINAP, Shanghai, People's Republic of China
	The slice energy spread of electron beam is a very important parameter for high gain free electron lasers (FELs) especially the seeded FELs. Because of its extremely small value, highly accurate measurement of the slice energy spread is rather challenging. In this paper, we propose a novel method to accurately measure the slice energy spread based on the coherent harmonic generation (CHG) scheme. This method has been demonstrated on the Shanghai deep ultraviolent FEL (SDUV-FEL), and the results show that the slice energy spread is about only 1.2keV at the exit of the 136MeV linac when the bunch compressor is off, and this value change to about 2.6keV when the bunch compressor is on. * Chao Feng, et al, Phys. Rev. ST Accel. Beams 14, 090701 (2011)
	Slides WEOBB01 [3.309 MB]

WEOBB02	Refraction Contrast Imaging via Laser-Compton X-Ray Using Optical Storage Cavity	electron, cavity, photon, linac	2146
	K. Sakaue, T. Aoki, M. Washio RISE, Tokyo, Japan M.K. Fukuda, Y. Honda, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan
	We have been developing a pulsed-laser storage technique in a super-cavity for a compact x-ray sources. The pulsed-laser super-cavity enables to make high peak power and small waist laser at the collision point with the electron beam. Recently, using 357 MHz mode-locked Nd:VAN laser pulses which stacked in a super-cavity scattered off a multi-bunch electron beam, we obtained a multi-pulse x-rays through the laser-Compton scattering. Then, we performed a X-ray imaging via laser-Compton X-ray. The images have edge enhancement by refraction contrast because the X-ray source spot size was small enough. This is one of the evidences that laser-Compton X-ray is high quality. Our laser-Compton experimental setup, the results of X-ray imaging and future prospective will be presented at the conference.
	Slides WEOBB02 [4.393 MB]

WEIC06	Accelerator R&D: Research for Science - Science for Society	acceleration, hadron, proton, emittance	2161
	N.R. Holtkamp SLAC, Menlo Park, California, USA S. Biedron, S.V. Milton CSU, Fort Collins, Colorado, USA L. Boeh, J.E. Clayton, G. Zdasiuk VMS GTC, Palo Alto, California, USA S.A. Gourlay, M.S. Zisman LBNL, Berkeley, California, USA R.W. Hamm R&M Technical Enterprises, Pleasanton, California, USA S. Henderson Fermilab, Batavia, USA G.H. Hoffstaetter CLASSE, Ithaca, New York, USA L. Merminga TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada S. Ozaki BNL, Upton, Long Island, New York, USA F.C. Pilat JLAB, Newport News, Virginia, USA M. White ANL, Argonne, USA
	In September 2011 the US Senate Appropriations Committee requested a ten-year strategic plan from the Department of Energy (DOE) that would describe how accelerator R&D today could advance applications directly relevant to society. Based on the 2009 workshop "Accelerators for America’s Future" an assessment was made on how accelerator technology developed by the nation’s laboratories and universities could directly translate into a competitive strength for industrial partners and a variety of government agencies in the research, defense and national security sectors. The Office of High Energy Physics, traditionally the steward for advanced accelerator R&D within DOE, commissioned a task force under its auspices to generate and compile ideas on how best to implement strategies that would help fulfill the needs of industry and other agencies, while maintaining focus on its core mission of fundamental science investigation.
	Slides WEIC06 [3.678 MB]

WEEPPB001	Progress Toward a High-Transformer-Ratio Dielectric Wakefield Experiment at FLASH	electron, wakefield, acceleration, simulation	2166
	F. Lemery, D. Mihalcea, P. Piot Northern Illinois University, DeKalb, Illinois, USA J. Osterhoff MPQ, Garching, Munich, Germany C.A.J. Palmer DESY, Hamburg, Germany P. Stoltz Tech-X, Boulder, Colorado, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357 Dielectric wakefield accelerators offer many advantages over conventional RF accelerators such as higher acceleration gradients and cost effectiveness. In this paper we describe our experimental plans to demonstrate enhanced transformer ratios with drive and witness bunches. The experiment, will be performed at the Free-electron LASer in Hamburg (FLASH) and utilizes unique pulse shaping capabilities using the dual-frequency superconducting linac to produce high transformer ratios (>2). The beam-driven acceleration mechanism will be based on a cylindrical-symmetric dielectric-lined waveguide (DLW). The experimental setup is described, and start-to-end numerical simulations of the experiment will be presented.

WEEPPB002	Plasma Acceleration Experiment at SPARC_LAB with External Injection	plasma, electron, acceleration, injection	2169
	L. Serafini, A. Bacci Istituto Nazionale di Fisica Nucleare, Milano, Italy M. Bellaveglia, M. Castellano, E. Chiadroni, G. Di Pirro, M. Ferrario, A. Gallo, G. Gatti, A.R. Rossi, C. Vaccarezza INFN/LNF, Frascati (Roma), Italy A. Cianchi Università di Roma II Tor Vergata, Roma, Italy C. Maroli, V. Petrillo Universita' degli Studi di Milano, Milano, Italy A. Mostacci URLS, Rome, Italy P. Tomassini Università degli Studi di Milano, Milano, Italy
	At the SPARC-LAB facility of INFN-LNF we are installing two transport lines for ultra-short electron bunches and an ultra-intense laser pulses, generated by the SPARC photo-injector and by the FLAME laser in a synchronized fashion at the tens of fs level, to co-propagate inside a hydrogen filled glass capillary, in order to perform acceleration of the electron bunch by a plasma wave driven by the laser pulse. The main aim of this experiment is to demonstrate that a high brightness electron beam can be accelerated by a plasma wave without any significant degradation of its quality. A 10 pC electron bunch, 10 fs long is produced by SPARC and transported to injection into the capillary, which is 100 micron wide, at a gas density around 5*10¹⁷ ne/cm³ . The laser pulse, 25 fs long, focused down to 30 microns into the capillary is injected ahead of the bunch, drives a weakly non-linear plasma wave with wavelength of about 120 microns. A proper phasing of the two pulses allows acceleration of electrons from the injection energy of 150 MeV up to about 1 GeV for a 10 cm long capillary. Installation of the beam lines is foreseen by the end of 2012 and first tests starting in mid 2013.

WEEPPB003	Modeling of 10 GeV-1 TeV Laser-Plasma Accelerators Using Lorentz Boosted Simulations	plasma, acceleration, simulation, controls	2172
	J.-L. Vay, E. Esarey, C.G.R. Geddes, W. Leemans, C.B. Schroeder LBNL, Berkeley, California, USA E. Cormier-Michel Tech-X, Boulder, Colorado, USA D.P. Grote LLNL, Livermore, California, USA
	Funding: Supported by US-DOE Contracts DE-AC02-05CH11231 and DE-AC52-07NA27344, US-LHC program LARP, and US-DOE SciDAC program ComPASS. Modeling of laser-plasma wakefield accelerators in an optimal frame of reference [J.-L. Vay, Phys. Rev. Lett. 98 130405 (2007)] allows direct and efficient full-scale modeling of deeply depleted and beam loaded laser-plasma stages of 10 GeV-1 TeV (parameters not computationally accessible otherwise). This verifies the scaling of plasma accelerators to very high energies and accurately models the laser evolution and the accelerated electron beam transverse dynamics and energy spread. Over 4, 5 and 6 orders of magnitude speedup is achieved for the modeling of 10 GeV, 100 GeV and 1 TeV class stages, respectively. Agreement at the percentage level is demonstrated between simulations using different frames of reference for a 0.1 GeV class stage. Obtaining these speedups and levels of accuracy was permitted by solutions for handling data input (in particular particle and laser beams injection) and output in a relativistically boosted frame of reference, as well as mitigation of a high-frequency instability that otherwise limits effectiveness. Used resources of NERSC, supported by US-DOE Contract DE-AC02-05CH11231.

WEEPPB004	Status of the APEX Project at LBNL	gun, cathode, cavity, electron	2173
	F. Sannibale, B.J. Bailey, K.M. Baptiste, J.M. Byrd, C.W. Cork, J.N. Corlett, S. De Santis, L.R. Doolittle, J.A. Doyle, P. Emma, J. Feng, D. Filippetto, G. Huang, H. Huang, T.D. Kramasz, S. Kwiatkowski, W.E. Norum, H.A. Padmore, C. F. Papadopoulos, G.C. Pappas, G.J. Portmann, J. Qiang, D.G. Quintas, J.W. Staples, T. Vecchione, M. Venturini, M. Vinco, W. Wan, R.P. Wells, M.S. Zolotorev, F.A. Zucca LBNL, Berkeley, California, USA M. J. Messerly, M.A. Prantil LLNL, Livermore, California, USA C.M. Pogue NPS, Monterey, California, USA
	Funding: This work was supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231. The Advanced Photo-injector Experiment (APEX) at the Lawrence Berkeley National Laboratory is focused on the development of a high-brightness high-repetition rate (MHz-class) electron injector for X-ray FEL applications. The injector is based on a new concept gun, utilizing a normal conducting 186 MHz RF cavity operating in cw mode in conjunction with high quantum efficiency photocathodes capable of delivering the required repetition rates with available laser technology. The APEX activities are staged in 3 main phases. In Phases 0 and I, the gun will be tested at its nominal energy of 750 keV and several different photocathodes are tested at full repetition rate. In Phase II, a pulsed linac will be added for accelerating the beam at several tens of MeV to reduce space charge effects and measure the high-brightness performance of the gun when integrated in an injector scheme. At Phase II energies, the radiation shielding configuration of APEX limits the repetition rate to a maximum of several Hz. Phase 0 is under commissioning, Phase I under installation, and initial activities for Phase II are underway. This paper presents an update on the status of these activities.

WEEPPB006	LCLS Femto-second Timing and Synchronization System Update	controls, LLRF, undulator, EPICS	2176
	G. Huang, J.M. Byrd, R.B. Wilcox LBNL, Berkeley, California, USA A.R. Fry, B.L. Hill SLAC, Menlo Park, California, USA
	Femto second timing and synchronization system has been installed on LCLS operation for 2 years. The requirement of more receiver at different location of the experimental hall urge us to develop a new version of receiver chassis and sync-head. Two sets of the new receiver chassis has been installed to the SXR and CXI end station. To help end user the diagnose the system, a intermediate GUI is developed to show some diagnostic information.

WEPPC013	Progress of High Gradient Performance in STF 9-cell Cavities at KEK	cavity, accelerating-gradient, status, HOM	2233
	Y. Yamamoto, H. Hayano, E. Kako, S. Noguchi, T. Shishido, K. Watanabe KEK, Ibaraki, Japan
	Vertical tests for ILC have been carried out since 2008 at KEK-STF. Measured cavities are from MHI#5 to MHI#22 (not yet for MHI#18-#22 at the end of November 2011), and MHI#12, #13 and #17 reached the ILC specification of 0.8x10¹⁰ at 35MV/m. The MHI cavity was added into the “qualified vendor” for the cavity yield. These three cavities (#12, #13 and #17) had no defect on every EBW seam of equator, iris and beampipe. On the other hand, the other cavities had a few or several defects on EBW seam. Especially, defect on the EBW seam of the equator is the worst case, and cavity performance is limited “certainly”. MHI#10, #15 and #16 cavities were limited by this kind of defect. As for iris region, MHI#14 had large defect at the iris between cell #8 and #9, and the performance was limited by the heavy field emission with “explosive event”. However, after the locally mechanical grind for this defect, the cavity performance was drastically improved with no field emission at 37MV/m. In this paper, the recent progress of the cavity performance at KEK-STF will be reported with the “detailed” defect analysis.

WEPPC034	LA³NET - An International Network on Laser Applications at Accelerators	ion, acceleration, diagnostics, electron	2281
	C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom C.P. Welsch The University of Liverpool, Liverpool, United Kingdom
	Funding: This project is funded by the European Union under contract PITN-GA-2011-289191. Lasers have become increasingly important for the successful operation and continuous optimization of particle accelerators: Laser-based particle sources are well suited for delivering the highest quality ion and electron beams, laser acceleration has demonstrated unprecedented accelerating gradients and might be an alternative for conventional particle accelerators in the future, and without laser-based beam diagnostics it would not be possible to unravel the characteristics of many complex particle beams. The LA³NET project will bring together research centers, universities, and industry partners to jointly train 17 early stage researchers. In addition, the consortium will also organize a number of international training events, such as schools, topical workshops and conferences. This contribution gives examples from the network's broad research program and summarizes planned training events.

WEPPD048	Laser Synchronization at REGAE using Phase Detection at an Intermediate Frequency	electron, controls, LLRF, feedback	2624
	M. Felber, M. Hoffmann, U. Mavrič, H. Schlarb, S. Schulz DESY, Hamburg, Germany W. Jałmużna TUL-DMCS, Łódź, Poland
	A new linear accelerator is being set up for electron diffraction experiments at DESY. This machine, called REGAE (Relativistic Electron Gun for Atomic Exploration) is composed of a photo-cathode gun and a buncher cavity. It uses a single laser system for both, the generation of the electron bunches and for pump-probe experiments. The required timing jitter between the electron bunches and the laser pulses at the experiment is in the order of 10 fs rms. The conventional method for laser synchronization using RF technique to measure phase-jitter in the baseband is susceptible to distortions caused by ground-loops and electro-magnetic interference. At REGAE a new scheme for an RF-based laser synchronization is deployed. It uses a down-converter which mixes a higher harmonic of the laser repetition rate down to an intermediate frequency (IF). The IF is digitized and its phase calculated. This information is used for the feedback controller keeping the laser and the RF synchronized.

WEPPD049	Characterization of the Engineered Photodiode-based Fiber Link Stabilization Scheme for Optical Synchronization Systems	LLRF, FEL, optics, controls	2627
	T. Lamb, M.K. Bock, M. Felber, F. Ludwig, H. Schlarb, S. Schulz DESY, Hamburg, Germany S. Jabłoński Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
	Pulsed optical synchronization systems are used in modern FELs like FLASH and will be used in the upcoming European XFEL. Their purpose is to distribute synchronization signals with femtosecond stability throughout the machine. Optical fibers are used to transport the pulses carrying the timing information to their end-stations. These fibers have to be continuously delay stabilized in order to achieve the desired precision. In this paper, a photodiode-based detector to measure the drifts of the fiber delay and allows their active correction is presented. Promising results from a first prototype setup of a photodiode-stabilized optical fiber link were the starting point for an engineering of this concept. An enclosure with free-space optics, fiber optics and integrated electronics for the detector, operating at 9.75 GHz, was designed. This unit includes all required parts to stabilize four fiber links. It allows to investigate the temperature sensitivity of the detector. Furthermore, results from drift measurements carried out with a two channel engineered detector are presented in this paper.

WEPPD052	Compression and Synchronization of MeV Scale Subpicosecond Electron Beams in a THz IFEL Interaction	undulator, electron, simulation, space-charge	2636
	J.T. Moody, R.K. Li, P. Musumeci, C.M. Scoby, H.L. To UCLA, Los Angeles, California, USA
	Recent development of MW peak power THz sources from efficient optical rectification of broadband IR pulses by pulse front tilting has made available laser locked single cycle THz pulses suitable for compression and laser-synchronization of photoinjector generated subpicosecond electron beams. Three dimensional simulations have shown that a waveguided 8 pulse THz train can be used to interact with a sub picoseconds electron beam in an undulator to achieve compression and laser synchronization. We present a THz pulse train source currently under development at UCLA PBPL as well as detailed 3 dimensional simulations including the effect of the interaction on transverse beam quality. DOE-BES No. DE-FG02-92ER40693 and DOE-BES No. DE-FG02-07ER46272

WEPPD053	The LLNL/UCLA High Gradient Inverse Free Electron Laser Accelerator	electron, undulator, acceleration, simulation	2639
	J.T. Moody, P. Musumeci UCLA, Los Angeles, California, USA G.G. Anderson, S.G. Anderson, M. Betts, S.E. Fisher, D.J. Gibson, A.M. Tremaine, S.S.Q. Wu LLNL, Livermore, California, USA
	Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. We describe the Inverse Free Electron Accelerator currently under construction at Lawrence Livermore National Lab. Upon completion of this accelerator, high brightness electrons generated in the photoinjector blowout regime and accelerated to 50 MeV by S-band accelerating sections will interact with > 4 TW peak power Ti:Sapphire laser in a highly tapered 50 cm undulator and experience an acceleration gradient of >200 MeV/m. We present the final design of the accelerator as well as the results of start to end simulations investigating preservation of beam quality and tolerances involved with this accelerator.

WEPPD054	Development of Pulsed Laser Systems and Cathode-performance Studies for the S-DALINAC Polarized Injector	cathode, electron, cavity, vacuum	2642
	M. Espig, C. Eckardt, J. Enders, Y. Fritzsche, N. Kurichiyanil, J. Lindemann, M. Wagner TU Darmstadt, Darmstadt, Germany
	A source of polarized electrons has recently been implemented at the superconducting Darmstadt electron linear accelerator S-DALINAC. We give an overview of the recent performance of the system. Photo-emission from a superlattice-GaAs photo-cathode is obtained from using either a DC diode laser or a short-pulse Ti:Sapphire laser system. For a robust pulsed quasi-cw operation, it is investigated whether a VECSEL system (Vertical-Cavity Surface-Emitting Laser) can be realized with a wavelength of 780 nm and a repetition rate of 3 GHz with pulse widths of a few picoseconds only. To enhance the availability and performance of the polarized source with respect to quantum efficiency, a separate atomic-hydrogen cleaning system for the cathodes is planned which will allow cathode treatment to be tested and optimized. Supported by DFG within CRC/SFB 634 and by the state of Hesse in the LOEWE-Center HIC for FAIR.

WEPPD055	Gamma-rays Generation with 3D 4-mirror Cavity for ILC Polarized Positron Source	cavity, photon, electron, scattering	2645
	T. Akagi, S. Miyoshi Hiroshima University, Graduate School of Advanced Sciences of Matter, Higashi-Hiroshima, Japan S. Araki, Y. Funahashi, Y. Honda, T. Okugi, T. Omori, H. Shimizu, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan H. Kataoka, T. Kon Seikei University, Japan M. Kuriki, T. Takahashi Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan K. Sakaue, M. Washio RISE, Tokyo, Japan R. Tanaka, H. Yoshitama Hiroshima University, Higashi-Hiroshima, Japan
	We are conducting gamma-rays generation experiment by the laser-Compton scattering using a Fabry-Perot cavity. We developed a 3D 4-mirror cavity, and it is installed at the KEK-ATF. By using a 3D 4-mirror cavity, small laser spot can be achieved with stable resonant condition. In addition, we aim 1900 times enhancement of input laser power by a 4-mirror cavity to increase the number of gamma-rays.

WEPPD056	Ytterbium Fiber Laser System of DAW RF Gun for SuperKEKB	emittance, gun, cavity, luminosity	2648
	X. Zhou, T. Natsui, Y. Ogawa, M. Yoshida KEK, Ibaraki, Japan
	For obtaining higher luminosity in the SuperKEKB, the photocathode DAW-type RF gun for high-current, low-emittance beams will be employed in the injector linac. The electron beams with a charge of 5 nC and a normalized emittance of 10 micrometer are expected generate in the photocathode RF gun by using the laser source with a center wavelength of 260 nm and a pulse width of 30 ps. Fiber laser especially Ytterbium(Yb) fiber have attracted attention as one of the promising practical alternatives to usual solid-state lasers, offering high energy-extraction efficiency, high repetition rate, high output power, low-cost and so on. Introducing the Ytterbium fiber laser system, we have developed a stable laser amplifier system, which could allow steady beam injection into the SuperKEKB rings. The laser system starts with a large mode-area Yb-doped fiber-based amplifier system, which consists of a passively mode-locked femtosecond Yb-fiber oscillator. To obtain the mJ-class pulse energy, a multi-pass solid-state amplifier is employed. Deep UV pulses for the photocathode are generated by using two frequency-doubling stages. High pulse energy and good stability would be expected.

WEPPD059	Proton Acceleration by a Relativistic Laser Frequency-Chirp Driven Plasma Snowplow	plasma, proton, electron, acceleration	2654
	A. A. Sahai, T.C. Katsouleas Duke ECE, Durham, North Carolina, USA R. Bingham STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom W.B. Mori, A. Tableman, F.S. Tsung, M. Tzoufras UCLA, Los Angeles, California, USA
	Funding: NSF-PHY-0936278, NSF-PHY-0904039 and NSFPHY-0936266, US DOE DE-FC02-07ER41500 and DE-FG02-92ER40727, DOE Fusion Science Center through a University of Rochester Subcontract No. 415025-G. We analyze the use of a relativistic laser pulse with a controlled frequency chirp incident on a rising plasma density gradient to drive an acceleration structure for proton and light ion acceleration. The Chirp Induced Transparency Acceleration (ChITA) scheme is described with an analytical model of the velocity of the snowplow at critical density on a pre-formed rising plasma density gradient that is driven by positive chirp in the frequency of a relativistic laser pulse. The velocity of the ChITA-snowplow is shown to depend upon rate of rise of the frequency of the relativistic laser pulse, the normalized magnetic vector potential of the laser pulse and the plasma density gradient scale-length. We observe using 1-D OSIRIS simulations the formation and forward propagation of ChITA-snowplow, being continuously pushed by the chirping laser at a velocity in accordance with the analytical results. The trace protons reflect off of this propagating snowplow structure and accelerate monoenergetically. The control over ChITA-snowplow velocity allows the tuning of accelerated proton energies.

WEPPD060	A Drive Laser for Multi-bunch Photoinjector Operation	electron, brightness, cathode, emittance	2657
	D.J. Gibson, C.P.J. Barty, M. J. Messerly, M.A. Prantil LLNL, Livermore, California, USA E. Cormier CELIA, Talence, France
	Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 Numerous electron beam applications would benefit from increased average current without sacrificing beam brightness. Work is underway at LLNL to investigate the performance of X-band photoinjectors that would generate electron bunches at a rate matching the RF drive frequency, i.e. one bunch per RF cycle. A critical part of this effort involves development of photo-cathode drive laser technology. Here we present a new laser architecture that can generate pulse trains at repetition rates up to several GHz. This compact, fiber-based system is driven directly by the accelerator RF and so is inherently synchronized with the accelerating fields, and scales readily over a wide range of drive frequencies (L-band through X-band). The system will be required to produce 0.5 μJ, ~200 fs rise time, spatially and temporally shaped UV pulses designed to optimize the electron beam brightness. Presented is the current status of this system, producing pulses shorter than 2 ps from a cw source.

WEPPD065	Development of a Laser-based Alignment System Utilizing Fresnel Zone Plates at the KEKB Injector Linac	alignment, scattering, linac, focusing	2672
	T. Suwada, M. Satoh KEK, Ibaraki, Japan K. Minoshima, S. Telada AIST, Tsukuba, Japan
	A new laser-based alignment system is under development in order to precisely align accelerator components along an ideal straight line at the 600-m-long KEKB injector linac. A well-known sequential three-point method with Fresnel zone plates and a CCD camera is revisited in the alignment system. The high-precision alignment system is strongly required in order to stably accelerate high-brightness electron and positron beams with high bunch charges and also to keep the beam stability with higher quality towards the Super B-factory at KEK. A new laser optics has been developed and the laser propagation characteristics has been systematically investigated at a 100-m-long straight section in vacuum. In this report, the experimental developments and investigations are reported along with the design of the new laser-based alignment system.

WEPPD073	Strategy and Validation of Fiducialization for the Pre-alignment of CLIC Components	alignment, controls, linac, target	2693
	S. griffet, A. Cherif, J. Kemppinen, H. Mainaud Durand, V. Rude, G. Sterbini CERN, Geneva, Switzerland
	The feasibility of the high energy e⁺ e⁻ linear collider CLIC (Compact Linear Collider) is very dependent on the ability to accurately pre-align its components. There are two 20-km-long Main Linacs which meet in an interaction point (IP). The Main Linacs are composed of thousands of 2 m long modules. One of the challenges is to meet very tight alignment tolerances at the level of CLIC module: for example, the center of a Drive Beam Quad needs to be aligned within 20 μm rms with respect to a straight line. Such accuracies cannot be achieved using usual measurement devices. Thus it is necessary to work in close collaboration with the metrology lab. To test and improve many critical points, including alignment, a CLIC mock-up is being assembled at CERN. This paper describes the application of the strategy of fiducialization for the pre-alignment of CLIC mock-up components. It also deals with the first results obtained by performing measurements using a CMM (Coordinate Measuring Machine) to ensure the fiducialization, using a Laser Tracker to adjust or check components’ positions on a girder and finally using a Measuring Arm to perform dimensional control after assembling steps.

WEPPD077	Generation of Picosecond Electron-bunch Trains with Variable Spacing Using a Multi-pulse Photocathode Laser	quadrupole, electron, wakefield, simulation	2705
	P. Piot Fermilab, Batavia, USA M.E. Conde, W. Gai, C.-J. Jing, R. Konecny, W. Liu, J.G. Power, Z.M. Yusof ANL, Argonne, USA D. Mihalcea, P. Piot, M.M. Rihaoui Northern Illinois University, DeKalb, Illinois, USA
	Funding: Work supported by DOE awards FG-02-08ER41532 and DE-AC02-06CH11357. We demonstrate the generation of a train of electron bunches with variable spacing at the Argonne Wakefield Accelerator. The photocathode ultraviolet laser pulse consists of a train of four pulses produced via polarization splitting using two alpha-BBO crystals. The photoemitted electron bunches are then manipulated in a horizontally-bending dogleg with variable longitudinal dispersion. A downstream vertically-deflecting cavity is then used to diagnose the temporal profile of the electron beam. The generation of a train composed of four bunches with tunable spacing is demonstrated. Such train of bunch could have application to, e.g., the resonant excitation of wakefield in dielectric-lined waveguides.

WEPPP006	Using Simulations to Understand Particle Dynamics and Resonance in the Micro-accelerator Platform	resonance, electron, coupling, acceleration	2732
	J.C. McNeur, G. Travish UCLA, Los Angeles, USA H. Hairong UESTC, Chengdu, Sichuan, People's Republic of China R.B. Yoder Manhattanville College, Purchase, New York, USA
	Funding: Work funded in part by grant HDTRA1-09-1-0043 from the US Defense Threat Reduction Agency and under a grant from NNSA/NA-221 Office of Nonproliferation and Verification Research and Development. The Micro-Accelerator Platform (MAP) is a slab-symmetric micron-scale electron accelerator. Electrons gain energy via a standing wave electromagnetic resonance powered by a side coupled Ti:Sapphire laser. In this paper, we will discuss simulations of resonance and particle dynamics in this structure. Three-dimensional simulations showing evidence of stable 1 GeV/m acceleration are detailed along with simulations studying defocusing and wakefield effects in the MAP. Additionally, optimization of the structure and the coupling of laser power into the cavity will be explored.

WEPPP008	Vacuum Laser Acceleration Experiment Perspective at Brookhaven National Lab-Accelerator Test Facility	electron, acceleration, vacuum, simulation	2735
	X.P. Ding, D.B. Cline, L.S. Shao UCLA, Los Angeles, California, USA M.G. Fedurin, K. Kusche, I. Pogorelsky, V. Yakimenko BNL, Upton, Long Island, New York, USA Y.K. Ho, Q. Kong Fudan University, Shanghai, People's Republic of China J.J. Xu Shanghai Institute of Optics and Fine Mechanics, Shanghai, People's Republic of China
	Funding: Supported by the DOE under award number DE-FG02-92ER40695 (UCLA) This paper presents the pre-experiment plan and prediction of the first stage of Vacuum Laser Acceleration (VLA) collaborating by UCLA, Fudan University and ATF-BNL. This first stage experiment is a Proof-of-Principle to support our previously posted novel VLA theory. Simulations show that based on ATF’s current experimental conditions, the electron beam with initial energy of 15MeV can get net energy gain from intense CO2 laser beam. The difference of electron beam energy spread is observable by ATF beam line diagnostics system. Further this energy spread expansion effect increases along with the laser intensity increasing. The proposal has been approved by ATF committee and experiment will be the next project.

WEPPP009	Experimental Progress Towards a Resonant Slab-symmetric Dielectric Laser Accelerator	simulation, electron, acceleration, vacuum	2738
	G. Travish, K.S. Hazra, G. Liu, J.C. McNeur, E.B. Sozer, J. Zhou UCLA, Los Angeles, California, USA H. Hairong UESTC, Chengdu, Sichuan, People's Republic of China R.B. Yoder Manhattanville College, Purchase, New York, USA
	Funding: Work funded in part by grant HDTRA1-09-1-0043 from the US Defense Threat Reduction Agency and under a grant from NNSA/NA-221 Office of Nonproliferation and Verification Research and Development. TheμAccelerator Platform (MAP), a resonant dielectric structure for laser acceleration of electrons, has been in development for a number of years. It consists of a a vacuum gap between two slab-shaped reflecting boundaries, with a transmissive grating diffractive optic on one boundary that allows laser power to propagate into the gap and enforces an accelerating mode. We report on the progress of bench and beam tests carried out within the last year, and the challenges faced in diagnosing <pC beams from optical-scale structures. We also describe refinements to our fabrication techniques and lessons learned during the development of the fabrication process.

WEPPP014	Modeling of Quasi-phase Matching in an Aperiodic Corrugated Plasma Waveguide for High-efficiency Direct Laser Electron Acceleration	electron, plasma, acceleration, simulation	2750
	M.W. Lin The Pennsylvania State University, University Park, Pennsylvania, USA I. Jovanovic Penn State University, University Park, Pennsylvania, USA
	Funding: This work is supported by the Defense Threat Reduction Agency through contract HDTRA1-10^-1-0034. Direct laser acceleration (DLA) of charged particles using the axial electric field of a radially polarized intense laser pulse has the potential to realize a compact accelerator required in security and medical applications. The implementation of guided propagation of laser pulses over long distances and the phase matching between electrons and laser pulses may limit the performance of DLA in reality. A corrugated plasma waveguide could be applied to extend the laser beam propagation distance and for quasi-phase matching between laser and electron pulses for net acceleration. To accelerate electrons from a low initial energy (for example, ~5 MeV from a photoinjector gun) up to hundreds of MeV, an aperiodic corrugated plasma waveguide with successive increase of on-axis density modulation period is needed. We conducted particle-in-cell simulations to design the appropriate aperiodic plasma structure for DLA. For each section of the corrugated waveguide, the dependence of density modulation period on the initial electron energy and laser pulse intensity is investigated. The simulation results are guiding the design of proof-of-principle experiments for compact, tabletop DLA. P. Serafim, et al., IEEE Trans. Plasma Sci. 28, 1155 (2000). ** J. P. Palastro, et al., Phys. Rev. E. 77, 036405 (2008).

WEPPP016	De-neutralization of Laser Produced Proton Pulse in a Strong Solenoidal Magnetic Field	electron, proton, simulation, focusing	2755
	M. Droba, O.K. Kester, O. Meusel, C. Wiesner IAP, Frankfurt am Main, Germany
	Laser generated proton pulses of ten to several ten MeV produced in PHELIX-laser facility at GSI Darmstadt poses some unique characteristics. The first systematic exploration of the interface between proton pulse generation via the TNSA mechanism and conventional accelerator technology is within the scope of the LIGHT (Laser Ion Generation, Handling and Transport) project. One of the main tasks is to study the beam dynamics in intense B-fields, especially in context of early de-neutralization and space charge effects. The 3D numerical simulations with co-moving electrons and up to 10⁷ macroparticles were performed to investigate the de-neutralization process in the focusing magnetic solenoid. Importance of the first focusing element and influence on beam parameters will be addressed. Results of the 3D simulation model will be presented and discussed.

WEPPP017	Recent Results at the SPARC_LAB Facility	electron, plasma, injection, photon	2758
	M. Ferrario, D. Alesini, M.P. Anania, M. Bellaveglia, R. Boni, M. Castellano, E. Chiadroni, G. Di Pirro, A. Drago, A. Esposito, A. Gallo, C. Gatti, G. Gatti, A. Ghigo, T. Levato, E. Pace, L. Pellegrino, R. Pompili, A.R. Rossi, B. Spataro, P. Tomassini, C. Vaccarezza, F. Villa INFN/LNF, Frascati (Roma), Italy A. Bacci, C. De Martinis, L. Serafini Istituto Nazionale di Fisica Nucleare, Milano, Italy A. Cianchi Università di Roma II Tor Vergata, Roma, Italy G. Dattoli, E. Di Palma, L. Giannessi, A. Petralia, M. Quattromini, C. Ronsivalle, I.P. Spassovsky, V. Surrenti ENEA C.R. Frascati, Frascati (Roma), Italy D. Di Giovenale INFN-Roma II, Roma, Italy U. Dosselli INFN, Roma, Italy R. Faccini INFN-Roma, Roma, Italy R. Fedele Naples University Federico II, Mathematical, Physical and Natural Sciences Faculty, Napoli, Italy M. Gambaccini INFN-Ferrara, Ferrara, Italy D. Giulietti UNIPI, Pisa, Italy L.A. Gizzi, L. Labate CNR/IPP, Pisa, Italy P. Londrillo INFN-Bologna, Bologna, Italy S. Lupi Università di Roma I La Sapienza, Roma, Italy A. Mostacci, L. Palumbo Rome University La Sapienza, Roma, Italy G. Passaleva INFN-FI, Sesto Fiorentino, Italy V. Petrillo Universita' degli Studi di Milano, Milano, Italy J.V. Rau ISM-CNR, Rome, Italy G. Turchetti Bologna University, Bologna, Italy
	A new facility named SPARC_LAB (Sources for Plasma Accelerators and Radiation Compton with Lasers and Beams) has been recently launched at the INFN National Labs in Frascati, merging the potentialities of the old projects SPARC and PLASMONX. The SPARC project, a collaboration among INFN, ENEA and CNR, is now completed, hosting a 150 MeV high brightness electron beam injector which feeds a 12 meters long undulator. Observation of FEL radiation in the SASE, Seeded and HHG modes has been performed from 500 nm down to 40 nm wevelength. A second beam line has been also installed to drive a narrow band THz radiation source. In parallel to that, INFN decided to host a 300 TW laser that will be linked to the linac and devoted to explore laser-matter interaction, in particular with regard to laser-plasma acceleration in the self injection and external injection modes, (the PLASMONX experiments). The facility will be also used for particle driven plasma acceleration experiments (the COMB experiment). A Thomson scattering experiment coupling the electron bunch to the high-power laser to generate coherent monochromatic X-ray radiation is also in the commissioning phase.

WEPPP019	Designing of Photonic Crystal Accelerator for Radiation Biology	electron, vacuum, injection, acceleration	2763
	K. Koyama, Y. Matsumura University of Tokyo, Tokyo, Japan A. Aimidula, M. Uesaka The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan T. Natsui, M. Yoshida KEK, Ibaraki, Japan
	Funding: This work was performed as part of the Global COE Program (Nuclear Education and Research Initiative, MEXT, Japan. A photonic crystal accelerator with a combination of a fiber laser is under development in order to apply it to the radiation biology. In order to investigate fundamental biological processes in a cell, a DNA is precisely shot by an electron bunch with an in situ observation of a radiation interaction using a microscope. Required beam diameter, bunch length, and beam energy are nanometer, attosecond, and 100 keV to 1 MeV, respectively. A photonic crystal or dielectric laser accelerator energized by a fiber laser is suitable for producing such a fine beam with a palm top device. A preliminary estimation shows that 200 keV electron bunch is available from a 0.8-mm-long accelerator and a few cm electron gun, which is driven by a few μJ, 5-ps laser pulse. We are developing a fiber laser in order to drive the photonic crystal accelerator. The Yb-fiber oscillator delivers mode-locked pulse train of ≈5 nJ/pulse at the repetition frequency of 62.5 MHz. The output pulse will be increased to several μJ by adopting a fiber amplifier

WEPPP029	Quasi-Monoenergetic Ion Bunch Generating by Two-Stage Laser Acceleration	ion, acceleration, target, light-ion	2787
	G. Dudnikova UMD, College Park, Maryland, USA D. Gorpinchenko ICM&MG SB RAS, Novosibirsk, Russia
	Experiments carried out in recent years on the laser-plasma interaction show the possibility of ions acceleration to high energy. The energy spectrum of these ions is typically broad. Practical applications require that the beams of accelerated ions be monoenergetic. A scheme is proposed for producing a quasi-monoenergetic ion bunch by irradiating a foil with two subsequent laser pulses–a prepulse followed by a stronger main pulse. We have demonstrated a possible mechanism for generating a quasi-monoenergetic ion bunch from a homogeneous target consisting of atoms of the same species by the two-stage acceleration. Results are presented from 2D and 3D PIC simulation that illustrate the scheme and determine the space–time and energy characteristics of the accelerated ions. Investigation was made by varying such control parameters as the duration and amplitude of the main laser pulse and the prepulse, the time lag between the pulses, and the thickness and density of the foil.

WEPPP030	Experimental Generation of a Double-bunch Electron Beam by Transverse-to-Longitudinal Phase Space Exchange	electron, focusing, cathode, gun	2789
	T.J. Maxwell, P. Piot Northern Illinois University, DeKalb, Illinois, USA A.S. Johnson, A.H. Lumpkin, J. Ruan, Y.-E. Sun, R.M. Thurman-Keup Fermilab, Batavia, USA
	Funding: Supported by Fermi Research Alliance, LLC under U.S. Dept. of Energy Contract No. DE-AC02-07CH11359, and Northern Illinois Univ. under US Dept. of Defense DURIP program Contract N00014-08-1-10⁶⁴. In this paper we demonstrate the generation of a tunable, longitudinal double-pulse electron beam. Experimental results on the generation of electron bunch trains with sub-picosecond structure have been previously reported where an initial transverse electron beam modulation was produced by masking the electron beam directly. Here the initial transverse structure is imparted by masking of the photoinjector drive laser to effectively produce two horizontally offset beams at photoemission in the RF gun. A longitudinal double-pulse modulation is then realized after a transverse-to-longitudinal phase-space exchange beamline. Longitudinal profile tuning is demonstrated by upstream beam focusing in conjunction with downstream monitoring of single-shot electro-optic spectral decoding of coherent transition radiation. Y.-E. Sun et al., Tunable Subpicosecond Electron-Bunch-Train Generation Using a Transverse-To-Longitudinal Phase-Space Exchange Technique, Phys. Rev. Lett. 10⁵, 234801 (2010).

WEPPP032	Inverse Free Electron Laser Acceleration Using Ultra-fast Solid State Laser Technology	undulator, simulation, acceleration, electron	2795
	S.G. Anderson, G.G. Anderson, S.M. Betts, S.E. Fisher, D.J. Gibson, A.M. Tremaine, S.S.Q. Wu LLNL, Livermore, California, USA J.T. Moody, P. Musumeci UCLA, Los Angeles, California, USA
	Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. We present a theoretical and computational study of the application of Ti:Sapphire laser technology to Inverse Free Electron Laser (IFEL) accelerators. Specifically, the regime in which the number of undulator periods is comparable to the number of cycles in the laser pulse is investigated and modifications to the IFEL accelerator equations and laser requirements are given. 1-D and 3-D simulations are used to study the IFEL interaction in this regime. In addition, the effects of non-Gaussian laser pulses, and astigmatic aberrations in the laser focus are analyzed. Finally, the tools developed for this study are applied to the LLNL/UCLA IFEL experiment, and potential future IFEL designs.

WEPPP036	Undulator Commissioning for a High-Energy-Gain Inverse Free Electron Laser Experiment	undulator, electron, simulation, acceleration	2804
	J.P. Duris, R.K. Li, P. Musumeci, E.W. Threlkeld UCLA, Los Angeles, California, USA
	Funding: This work was supported by DOE grant DE-FG02-92ER40693 and Defense of Threat Reduction Agency award HDTRA1-10^-1-0073. We present the construction and measurement details of a strongly tapered helical undulator for the Rubicon Inverse Free Electron Laser (IFEL) experiment. Results of the magnetic field measurements are presented, and these are used to produce simulations of the expected performance of the experiment. Finally, a study of the tolerances on the input parameters of the experiment is presented.

Paper

Title

Other Keywords

Page

MOOAA01

Performance of the Cornell High-Brightness, High-Power Electron Injector

cathode, gun, emittance, electron

20

B.M. Dunham, A.C. Bartnik, I.V. Bazarov, L. Cultrera, J. Dobbins, C.M. Gulliford, G.H. Hoffstaetter, R.P.K. Kaplan, V.O. Kostroun, Y. Li, M. Liepe, X. Liu, F. Löhl, P. Quigley, D.H. Rice, E.N. Smith, K.W. Smolenski, M. Tigner, V. Veshcherevich, Z. Zhao
CLASSE, Ithaca, New York, USA
S.S. Karkare, H. Li, J.M. Maxson
Cornell University, Ithaca, New York, USA

Funding: NSF DMR-0807731
The last year has seen significant progress in demonstrating the feasibility of a high current, high brightness photoinjector as required for the Energy Recovery Linac driven X-ray source at Cornell University. Both low emittances (0.4 mm-mrad rms normalized for 100% of the beam at 20 pC per bunch and 0.15 mm-mrad rms core emittance with 70% of the beam, and twice these values at 80 pC per bunch) and high average currents with a good lifetime well in excess of 1000 Coulombs at 5 MeV, 20 mA have been demonstrated. If these beams can be accelerated to 5 GeV without diluting the phase space, it would already provide a beam brightness higher than any existing storage ring. Operational experience, results, and the outlook for the future will be presented.

Slides MOOAA01 [1.424 MB]

MOOAA02

Instrumentation and Diagnostics for High Repetition Rate Linac-driven FELs

linac, FEL, emittance, diagnostics

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J.M. Byrd, S. De Santis, L.R. Doolittle, D. Filippetto, G. Huang, M. Placidi, A. Ratti
LBNL, Berkeley, California, USA

Funding: Work supported by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
One of the concepts for the next generation of linac-driven FELs is a cw superconducting linac driving an electron beam with MHz repetition rates. The beam is then switched into an array of independently configurable FELs. The demand for high brightness beams and the high rep-rate presents a number of challenges for the instrumentation and diagnostics. The high rep-rate also presents opportunities for increased beam stability because of the ability for much higher sampling rates for beam-based feedbacks. In this paper, we present our plans for instrumentation and diagnostics for such a machine.

Slides MOOAA02 [1.710 MB]

MOOAA03

Fast Feedback Strategies for Longitudinal Beam Stabilization

feedback, controls, electron, free-electron-laser

26

S. Pfeiffer, M.K. Bock, H. Schlarb, Ch. Schmidt
DESY, Hamburg, Germany
W. Jałmużna
TUL-DMCS, Łódź, Poland
G. Lichtenberg, H. Werner
TUHH, Hamburg, Germany

The key for pump-probe and seeding experiments at Free Electron Lasers such as FLASH is a femtosecond precise regulation of the bunch arrival time and compression. To maintain this beam based requirements, both for a single bunch and within a bunch train, it is necessary to combine field and beam based feedback loops. We present in this paper an advancement of the currently implemented beam based feedback system at FLASH. The principle of beam based modulation of the RF set point can be superimposed by a direct feedback loop with a beam optimized controller. Recent measurements of the achieved bunch arrival time jitter reduction to 20 fs have shown the performance gain by this direct feedback method *. The combination of both approaches will be presented and possible advantages are discussed.
* C. Schmidt et al., “Feedback Strategies for Bunch Arrival Time Stabilization at FLASH Towards 10 fs,” FEL’2011, Shanghai, August 2011, THPA26, http://www. JACoW.org.

Slides MOOAA03 [0.544 MB]

MOOBA03

Development of a High-power Coherent THz Sources and THz-TDS System on the basis of a Compact Electron Linac

electron, radiation, polarization, linac

37

M. Kumaki, K. Sakaue, M. Washio
RISE, Tokyo, Japan
R. Kuroda, H. Toyokawa, K. Yamada
AIST, Tsukuba, Ibaraki, Japan

The high-power terahertz time-domain spectroscopy (THz-TDS) has been developed on the basis of a compact S-band electron linac at AIST, Japan. It is strongly expected for inspection of dangerous materials in the homeland security field. The linac consists of a photocathode rf-gun, two acceleration tubes and a magnetic bunch compressor. The 40 MeV, 1 nC electron bunch is generated and compressed to less than 1 ps. THz radiations are generated in two methods with the ultra-short bunch. One is THz coherent synchrotron radiation (CSR). The other is THz coherent transition radiation (CTR). In the preliminary experiment, it was observed that the focused CTR had the donut profile in a transverse fields due to its initial radial polarization, so that it made Z-polarization. In case of the THz-TDS experiment, CTR was controlled to linearly polarization with the polarizer and focused to an EO crystal to obtain a THz temporal waveform which leads to THz spectrum with Fourier transform. The timing measurement between CTR and a probe laser was realized with OTR using a same optical photodiode. In this conference, we will describe details of our linac and results of the THz-TDS experiment.

Slides MOOBA03 [3.342 MB]

MOOAC01

The European XFEL LLRF System

LLRF, cavity, cryomodule, klystron

55

J. Branlard, G. Ayvazyan, V. Ayvazyan, M.K. Grecki, M. Hoffmann, T. Jeżyński, I.M. Kudla, T. Lamb, F. Ludwig, U. Mavrič, S. Pfeiffer, H. Schlarb, Ch. Schmidt, H.C. Weddig, B.Y. Yang
DESY, Hamburg, Germany
P. Barmuta, S. Bou Habib, L. Butkowski, K. Czuba, M. Grzegrzółka, E. Janas, J. Piekarski, I. Rutkowski, D. Sikora, L. Zembala, M. Żukociński
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
W. Cichalewski, K. Gnidzińska, W. Jałmużna, D.R. Makowski, A. Mielczarek, A. Napieralski, P. Perek, A. Piotrowski, T. Pożniak, K.P. Przygoda
TUL-DMCS, Łódź, Poland
S. Korolczuk, J. Szewiński
The Andrzej Soltan Institute for Nuclear Studies, Centre Świerk, Świerk/Otwock, Poland
K. Oliwa, W. Wierba
IFJ-PAN, Kraków, Poland

The European X-ray free electron laser accelerator consists of 800 superconducting cavities grouped in 25 RF stations. The challenges associated with the size and complexity of this accelerator required a high-precision, modular and scalable low level RF (LLRF) system. TheμTCA technology (uTCA) was chosen to support this system and adapted for RF standards. State-of-the-art hardware development in close collaboration with the industry allowed for the system continuity and maintainability. The complete LLRF system design is now in its final phase and the designed hardware was installed and commissioned at FLASH. The uTCA hardware system, measurement results and system performance validation will be shown. Operational strategy and plans for future automation algorithms for performance optimization will also be presented in this paper.

Slides MOOAC01 [12.188 MB]

MOEPPB014

Time Jitter Measurements in Presence of a Magnetic Chicane in the FERMI@elettra Linac

electron, linac, FEL, dipole

109

G. Penco, P. Craievich, S. Di Mitri, M.M. Milloch, F. Rossi
ELETTRA, Basovizza, Italy

Accurate and highly stable temporal synchronization between an electron bunch and a pulse from an external seed laser is one of the key requirements for successful operation of a seeded FEL in the XUV and soft x-ray regime. These requirements become more stringent when the electron bunch is longitudinally compressed to sub-ps durations in order to increase the current for more efficient FEL action. In this paper we present experimental measurements of the electron bunch arrival time jitter after the first magnetic compressor of FERMI@Elettra seeded FEL as a function of the compression factor. The experimental behavior of the pulse-to-pulse time jitter agrees both with results from tracking code simulations and with predictions from an analytical approach that takes into account the different sources of time jitter in FERMI, namely the photoinjector drive laser, the RF accelerating cavity phases and voltages, and fluctuations in the chicane bending magnet currents. We also present predictions for the expected arrival time jitter in the final configuration of FERMI that includes two bunch compressors and for which the synchronization requirement is of order 100 fs or better.

MOPPC056

The SolMaxP Code

plasma, simulation, target, beam-transport

259

A. Chancé, N. Chauvin, R.D. Duperrier
CEA/DSM/IRFU, France

In modern sciences, use of high performance computing (HPC) has become a necessity to move forward in the modeling of complex systems. For large-scale instruments like accelerators, HPC permits the virtual prototyping of very onerous parts and, thus, helps to reduce development costs. The SolMaxP code (for Solving Maxwell in Plasma) has been developed to allow complex simulations of multi-species plasma coupled with electromagnetic fields, whether the electromagnetic background is or is not self-consistent with the plasma dynamics. This paper presents the main algorithm of the code and gives several examples of applications.

MOPPD004

oPAC - Optimizing Accelerators through International Collaboration

simulation, controls, instrumentation, emittance

373

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

Funding: Work supported by the European Union under contract PITN-GA-2011-289485.
The optimization of the performance of any particle accelerator critically depends on an in-depth understanding of the beam dynamics in the machine and the availability of simulation tools to study and continuously improve all accelerator components. It also requires a complete set of beam diagnostics methods to monitor all important machine and beam parameters with high precision and a powerful control and data acquisition system. Within the oPAC project all these aspects will be closely linked with the aim to optimize the performance of present and future accelerators that lie at the heart of many research infrastructures. The project brings together 22 institutions from around the world. With a project budget of 6 M€, it is one of the largest research and training networks ever funded by the EC. This contribution gives an overview of the network's broad research program and summarizes the training events that will be organized by the consortium within the next 4 years.

MOPPD006

Commissioning of the 2MeV Electron Cooler for COSY / HESR

electron, high-voltage, solenoid, gun

379

V. Kamerdzhiev, J. Dietrich
FZJ, Jülich, Germany
V.N. Bocharov, M.I. Bryzgunov, A.D. Goncharov, V.M. Panasyuk, V.V. Parkhomchuk, V.B. Reva, D.N. Skorobogatov
BINP SB RAS, Novosibirsk, Russia

The new electron cooler for COSY is built at BINP Novosibirsk. Electron beam commissioning is in progress. Installation in COSY and commissioning with proton beam is scheduled for the beginning of 2012. Beam cooling with up to 3 A of electron current at up to 2 MeV is expected to boost the luminosity in the entire energy range of COSY by counteracting the effects caused by dense targets interacting with the circulating beam. Furthermore, the 2 MeV electron cooler can be used for beam cooling at injection energy in the HESR ring in the FAIR project. The electron beam is guided by a solenoidal magnetic field all the way from the electron gun to the collector. A cascade transformer provides power to numerous high voltage sections, short solenoids, and the collector inside a pressure vessel filed with SF6 gas. Commissioning results are reported.

MOPPD011

Analysis of Frequency Spectrum of Bunched Beam Related to Transverse Laser Cooling*

synchrotron, betatron, coupling, ion

391

K. Jimbo
Kyoto University, Institute for Advanced Energy, Kyoto, Japan
Z.Q. He
TUB, Beijing, People's Republic of China
M. Nakao, A. Noda, H. Souda, H. Tongu
Kyoto ICR, Uji, Kyoto, Japan

Using synchro-betatron coupling, transverse laser cooling is pursued at an ion storage/cooler ring, S-LSR, Kyoto University. A bunched 40 keV 24Mg+ beam was cooled by a co-propagating laser of 280 nm wavelength. Synchrotron oscillation in the longitudinal direction and betatron oscillation in the horizontal direction were intentionally coupled by an RF drift tube located at the finite dispersive section (D =1.1 m) where longitudinal cooling force was transmitted to the horizontal direction.* Analyzing bunched Schottky signals, which represents longitudinal physical quantities of the beam, we try to obtain an evidence of synchro-betatron coupling and accordingly laser cooling of the beam in the transverse direction.
* H. Okamoto, Phys. Rev. E 50, 4982 (1994)

MOPPD012

Challenge for More Efficient Transverse Laser Cooling for Beam Crystallization

synchrotron, ion, simulation, betatron

394

A. Noda, M. Nakao, H. Souda, H. Tongu
Kyoto ICR, Uji, Kyoto, Japan
M. Grieser
MPI-K, Heidelberg, Germany
Z.Q. He
TUB, Beijing, People's Republic of China
K. Ito, H. Okamoto, K. Osaki
HU/AdSM, Higashi-Hiroshima, Japan
K. Jimbo
Kyoto University, Institute for Advanced Energy, Kyoto, Japan
Y. Yuri
JAEA/TARRI, Gunma-ken, Japan

Funding: Work supported by Advanced Compact Accelerator Development project by MEXT. Also supported by GCOE project at Kyoto University, The next generation of Physics-Spun from Universality and Emergency.
At S-LSR in ICR, Kyoto University, Mg ion beam has been successfully laser cooled both in longitudinal* and transverse** directions. The cooling rate, however, is not strong enough to realize the crystalline beam due to the heating because of intra-beam scattering (IBS) effect. So as to suppress this IBS, reduction of the beam intensity is inevitable, which however, had resulted in poor S/N ratio for observation of the transverse beam size. In the present paper, we would like to describe a new beam scraping scheme, which selects out the beams in the distribution tail of the transverse phase space keeping the beam density in the core part by simultaneous application of multi-dimensional laser cooling and beam scraping. The strategy to reduce the beam intensity and hence beam heating due to IBS by a controlled scraping of the outskirt beam keeping the beam density at core part almost the same, has been searched by combination of the beam experiments and computer simulations.
* M. Tanabe et al., Applied Physics Express 1, 028001 (2008).
** M. Nakao et al., submitted to PRST-AB.

MOPPD013

Observation of 2-Component Bunched Beam Signal with Laser Cooling

betatron, ion, coupling, injection

397

H. Souda, M. Nakao, A. Noda, H. Tongu
Kyoto ICR, Uji, Kyoto, Japan
M. Grieser
MPI-K, Heidelberg, Germany
Z.Q. He
TUB, Beijing, People's Republic of China
K. Ito, H. Okamoto
HU/AdSM, Higashi-Hiroshima, Japan
K. Jimbo
Kyoto University, Institute for Advanced Energy, Kyoto, Japan
Y. Yuri
JAEA/TARRI, Gunma-ken, Japan

Funding: Work supported by Advanced Compact Accelerator Development Project of MEXT, Global COE program "The Next Generation of Physics, Spun from Universality and Emergence" and Grant-in-Aid for JSPS Fellows.
Longitudinal beam temperature during a laser cooling was measured through bunch length measurement at S-LSR. 40keV 24Mg+ beams were bunched by an RF voltage with a harmonic number of 5 and were cooled by a co-propagating laser with a wavelength of 280nm*. Bunch length was measured by time-domain signal from a pair of parallel-plate electrostatic pickups with a length of 140mm. Injected non-cooled beams gave a bunch length of 2.5m (2-σ) and cooled beam has a 2-component of broad and sharp distribution. Broad distribution had a longitudinal length of 2.2m, which is close to that of initial beam. The length of the sharp distribution shrunk to 0.25m and is considered as a cooled part. Capture efficiency of cooling, which represents the ratio of the particle numbers of cooled part and the total particle number, varies by the change of the detuning of the laser (fixed frequency or scanning). With scanning range of 2GHz, capture efficiency was improved from 66% to 92%, whereas the bunch became longer by 10% with scanning. Approach to improve the number of cooled particle and cut uncooled part** will be applied to attain a strong signal with a low-current beam with a low temperature.
* J. S. Hangst et al., Phys. Rev. Lett. 74, 4432 (1995).
** A. Noda et al., these proceedings.

MOPPD036

Gabor Lens Focusing for Medical Applications

ion, proton, space-charge, focusing

442

J.K. Pozimski, M. Aslaninejad
Imperial College of Science and Technology, Department of Physics, London, United Kingdom

The widespread introduction of Hadron therapy for cancer treatment is inhibited by the large costs for the accelerator and treatment facility and the subsequent maintenance costs which reflects into the cost per treatment. In the long term future (laser) plasma wakefield accelerated hadrons could offer compact treatment devices with significantly reduced treatment costs. In the moment the particle distributions produced by such accelerators do not fulfill the medical requirements by far. Never the less steady progress on the field might change the situation in the future. Beside the reliable production of a sufficient number of ions at the required energy the formation of a particle beam suitable for treatment from the burst of ions created in the acceleration process is one of the major challenges. While conventional optical systems will be operating at the technical limits which would be contradictory to the cost argument, space charge lenses of the Gabor type might be a cost effective alternative. In this paper a beam line consisting of such lenses will be presented together with particle transport simulations.

MOPPP004

Further Study on Fast Cooling in Compton Storage Rings

electron, storage-ring, simulation, photon

571

E.V. Bulyak
NSC/KIPT, Kharkov, Ukraine
J. Urakawa
KEK, Ibaraki, Japan
F. Zimmermann
CERN, Geneva, Switzerland

Compton sources can produce gamma-ray photons of ultimate intensity, but suffer from the large recoils experienced by the circulating electrons scattering off the laser photons. We have previously proposed a scheme called asymmetric fast cooling to reduce the beam energy spread in Compton rings. This report presents results of further studies on the fast cooling. In particular, we show that (1) a proper asymmetric setup of the scattering point results in significant reduction of the quantum losses of electrons in Compton rings with moderate energy acceptance, and (2) the optimized pulsed mode of operation in synchrotron-dominated rings enhances the overall performance of such gamma-ray sources. Theoretical results presented are in good accordance with numerical simulations. We discuss the performance of an existing storage ring such as KEK ATF DR equipped with an optical cavity and presently available laser system.

MOPPP005

Feasibility of THz Source Based on Coherent Smith-Purcell Radiation Generated by Femtosecond Electron Bunches in Super-Radiant Regime

radiation, electron, simulation, gun

574

L.G. Sukhikh, K.P. Artyomov, A. Potylitsyn
Tomsk Polytechnic University, Tomsk, Russia
A.S. Aryshev, J. Urakawa
KEK, Ibaraki, Japan
V. Karataev
JAI, Egham, Surrey, United Kingdom

Nowadays there is a big interest to THz radiation that is a promising tool for investigations in material science, in biology, medicine and other fields. THz radiation for users is mostly produced by Light Sources that are big and complex machines. Because of this there are numerous activities in research and development of a compact THz source. One of the trends is based on using different types of radiation generated in coherent regime by short electron bunches. The promising radiation mechanism is coherent Smith-Purcell radiation (CSPR) that has monochromatic angular distribution and that is generated while the bunch travels in a vicinity of a grating. In this report we present simulated characteristics of frequency-locked coherent Smith-Purcell radiation (super-radiant regime) generated by a train of short (hundreds of femtosecond) 10 MeV electron bunches with THz spacing. The simulations are performed for different grating profiles and parameters using existing CSPR models and Particle-in-Cell simulation code. We also discuss the feasibility of the THz source based on CSPR and status of the experiment that is prepared at LUCX facility at KEK after the upgrade.

MOPPP006

Inverse Cherenkov Radiation based on Smith-Purcell Effect

radiation, electron, linac, gun

577

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

Inverse Cherenkov radiation based on Smith-Purcell effect using metamaterial was investigated. A metallic grating and picosecond electron bunch of 27 MeV beam energy from a thermionic DC gun and linac were used for the inverse radiation. The frequency spectra in terahertz (THz) range were measured by a Michelson interferometer experimentally. Peaks of discrete component in the spectra shifted continuously according to the radiation angles, e. g. discrete peak changing from 0.117 to 0.085 THz with radiation angle along the electron bunch from 102 to 134 degree (backward) using a 2-mm-period metallic grating. In this presentation, experiment using another electron bunch generated by a photocathode RF gun linac will be reported.

MOPPP008

Hard X-ray Generation Experiment at Tsinghua Thomson Scattering X-Ray Source

electron, photon, scattering, background

583

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

Recently, there is increasing industrial and scientific interesting in ultra-fast, high peak brightness, tunable energy and polarization, monochromatic hard X-ray source. The X-ray source based on the Thomson scattering between the relativistic electron beam and TW laser pulse is the suitable candidate for its compact and affordable alternatives for high brightness hard monochromatic X-ray generation. Accelerator laboratory in Tsinghua University al so proposed and built Tsinghua Thomson scattering X-ray source. The hard x-ray pulse has been generated in experiment with 47 MeV electron and 20 TW laser in this year, and the parameters of the X-ray have been measured preliminarily. The experimental results are presented and discussed in this paper.

MOPPP009

X-Ray Spectra Reconstruction of Thomson Scattering Source From Analysis of Attenuation Data

scattering, photon, simulation, target

586

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

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

MOPPP011

Narrow Band Optimization of a Compton Gamma-Ray Source Produced From an X-Band Linac

electron, simulation, emittance, linac

592

F. Albert, S.G. Anderson, C.P.J. Barty, D.J. Gibson, F.V. Hartemann, R.A. Marsh, S.S.Q. Wu
LLNL, Livermore, California, USA

Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
Nuclear photonics is an emerging field of research that will require high precision gamma-ray (MeV) sources. In particular, nuclear resonance fluorescence applications necessitate a low (< 1%) relative gamma-ray spectral width. Within this context, Compton scattering, where laser photons are scattered off relativistic electron beams to produce tunable, collimated gamma rays, will produce the desired gamma-ray output. This paper will present the spectral narrowband optimization of such a light source currently being built at LLNL. In this case, PARMELA and elegant simulations of the full 250 MeV, high-gradient X-band linac provide the properties of the high brightness electron bunch. The electron beam simulations are then implemented into our newly developed weakly nonlinear Compton scattering code to produce theoretical gamma-ray spectra. The influence that the electron beam, laser beam and interaction geometry parameters have on the produced gamma-ray spectra will be shown with our simulations.

MOPPP029

Photocathodes at FLASH

cathode, electron, photon, gun

625

S. Lederer, H. Hansen, H.-H. Sahling, S. Schreiber
DESY, Hamburg, Germany
P. Michelato, L. Monaco, D. Sertore
INFN/LASA, Segrate (MI), Italy

For several years, cesium telluride photocathodes have been successfully used in the photoinjector of the Free-Electron-Laser FLASH at DESY, Germany. They show a high quantum efficiency and long lifetime and produce routinely thousands of bunches per second with a single bunch charge mostly in the range of 0.3 to 1 nC. Recent studies on lifetime, quantum efficiency, dark current, and operating experience is reported. At DESY, a new preparation system has been set-up. First cathodes have been produced and tested.

MOPPP032

Longitudinal Phase Space Studies at the PITZ Facility

electron, radiation, gun, FEL

631

M. Mahgoub, J.W. Bähr, H.-J. Grabosch, M. Groß, L. Hakobyan, G. Klemz, G. Kourkafas, M. Krasilnikov, D. Malyutin, A. Oppelt, M. Otevřel, B. Petrosyan, K. Rosbach, F. Stephan, G. Vashchenko
DESY Zeuthen, Zeuthen, Germany
I.I. Isaev
MEPhI, Moscow, Russia
Ye. Ivanisenko
IERT, Kharkov, Ukraine
M. Khojoyan
ANSL, Yerevan, Armenia
J. Li
USTC/NSRL, Hefei, Anhui, People's Republic of China
B. Marchetti
INFN-Roma II, Roma, Italy
D. Richter
HZB, Berlin, Germany
J. Rönsch-Schulenburg
Uni HH, Hamburg, Germany

Photoinjectors are a cornerstone for short-wavelength Free Electron Lasers (FELs) like FLASH and the European XFEL in Hamburg, Germany. The Photo Injector Test facility at DESY, location Zeuthen (PITZ), was built to develop and optimize such photoinjectors. The PITZ facility is capable of generating long trains of electron bunches, which can be accelerated up to ~25 MeV/c. Studying and optimizing the longitudinal properties of the electron bunch is an important topic at PITZ. A streak system consisting of Silica Aerogel radiators, optical transition radiation (OTR) screens, optical transmission line, and a streak camera is used to study the longitudinal properties with an accuracy of some ps. Due to the high radiation level in the facility, many of the lenses in the optical transmission line have turned brown, reducing the efficiency of the system. Some of the lenses were recovered by baking them up to 180°C. In contrast, few sensitive objective lenses can not be baked, rather they were recovered via exposure to infrared radiation with the proper wave length. An overview of the system, the difficulties, and the modifications needed to overcome the radiation effects are presented.

MOPPP035

Initial Emittance and Temporal Response Measurement for GaAs Based Photocathodes

electron, cathode, emittance, cavity

640

S. Matsuba
Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan
Y. Honda, T. Miyajima, T. Uchiyama, M. Yamamoto
KEK, Ibaraki, Japan
X.G. Jin
Institute for Advanced Research, Nagoya, Japan
Y. Takeda
Nagoya University, Nagoya, Japan

For future light source based on Energy Recovery Linac (ERL) is planned in KEK. For the ERL, an ultra low emittance and fast temporal response and high current electron source is needed. To achieve these requirements, a high voltage DC gun with a Negative Electron Affinity photo-cathode is under development. In this development, it is important to investigate the performance of photo-cathodes. We have constructed an ERL gun test stand to measure emittance and temporal profile. We use a solenoid scan technique for emittance measurements and a deflecting cavity technique for temporal profile measurements. In this presentation, we introduce KEK ERL gun test stand and beam test results.

MOPPP038

Optics Design and Layout for the Electron Beam Test Facility at Daresbury Laboratory

gun, quadrupole, beam-transport, emittance

646

D. Angal-Kalinin, J.W. McKenzie, B.L. Militsyn
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
J.K. Jones
Cockcroft Institute, Warrington, Cheshire, United Kingdom

An Electron Beam Test Facility (EBTF) is being developed at Daresbury Laboratory to provide the beam for industrial applications and as a front end of future light source facility test under consideration. The RF photoinjector will deliver ~6 MeV beam to industrial users* and will serve as an injector for the future light source facility under consideration at Daresbury**. The Photoinjector design in first phase consists of 2.5 cell RF gun (on loan from Strathclyde) to be driven by Ti:S laser. The photo injector design is aimed to deliver bunches with 10-250 pC bunch charge at low transverse emittances and short bunch lengths. The beam transport optics design described in this paper includes a dedicated diagnostics section capable of measuring ultra short and ultra low emittance bunches and transport to two user areas.
* P. McIntosh, these proceedings.
** J. Clarke, these proceedings.

MOPPP039

Masked Photocathode for Photoinjectors

electron, cathode, emittance, vacuum

649

J. Qiang
LBNL, Berkeley, California, USA

Funding: This research was supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. This research used resources of the NERSC.
In this paper, we propose using masked photocathode in photoinjector for generating high brightness electron beam. An electrode with small hole is used as a mask to shield a large size photocathode from accelerating vacuum chamber. Using a mask will significantly increase lifetime of a photocathode by rotating unexplored photocathode material behind the electrode into the hole. Furthermore, the mask helps reduce dark current or secondary electron emission from the photocathode material. It also provides a control of initial beam transverse emittances.

MOPPP041

Effect of Roughness on Emittance of Potassium Cesium Antimonide Photocathodes

emittance, cathode, electron, extraction

655

T. Vecchione, J. Feng, H.A. Padmore, W. Wan
LBNL, Berkeley, California, USA
I. Ben-Zvi, M. Ruiz-Osés, L. Xue
Stony Brook University, Stony Brook, USA
D. Dowell
SLAC, Menlo Park, California, USA
T. Rao, J. Smedley
BNL, Upton, Long Island, New York, USA

Funding: This work was supported by the Director, Office of Science, Office of Basic Energy Sciences of the U. S. Department of Energy, under Contract DE-AC02-05CH11231, KC0407-ALSJNT-I0013, and DE-SC0005713
Here we present first measurements of the effect of roughness on the emittance of K2CsSb photocathodes under high fields. We show that for very thin cathodes the effect is negligible at up to 3 MV/m but for thicker and more efficient cathodes the effect becomes significant. We discuss ways to modify the deposition to circumvent this problem.

MOPPP042

Modeling Multi-bunch X-band Photoinjector Challenges

emittance, gun, electron, linac

658

R.A. Marsh, S.G. Anderson, C.P.J. Barty, D.J. Gibson, F.V. Hartemann
LLNL, Livermore, California, USA

Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
An X-band test station is being developed at LLNL to investigate accelerator optimization for future upgrades to mono-energetic gamma-ray (MEGa-Ray) technology at LLNL. The test station will consist of a 5.5 cell X-band rf photoinjector, single accelerator section, and beam diagnostics. Of critical import to the functioning of the LLNL X-band system with multiple electron bunches is the performance of the photoinjector. In depth modeling of the Mark 1 LLNL/SLAC X-band rf photoinjector performance will be presented addressing important challenges that must be addressed in order to fabricate a multi-bunch Mark 2 photoinjector. Emittance performance is evaluated under different nominal electron bunch parameters using electrostatic codes such as PARMELA. Wake potential is analyzed using electromagnetic time domain simulations using the ACE3P code T3P. Beam-loading effects and low level rf compensation schemes are explored as well, using a semi-analytic formalism and computer algorithm. Plans for multi-bunch experiments and implementation of photoinjector advances for the Mark 2 design will also be discussed.

MOPPP045

Status of the Wisconsin SRF Gun

cavity, cathode, gun, solenoid

661

R.A. Legg, J. Bisognano, M.J. Bissen, R.A. Bosch, D. Eisert, M.V. Fisher, M.A. Green, K. Jacobs, R.G. Keil, K.J. Kleman, J.G. Kulpin, G.C. Rogers, M.C. Severson
UW-Madison/SRC, Madison, Wisconsin, USA
D. Yavuz
UW-Madison/PD, Madison, Wisconsin, USA

Funding: The University of Wisconsin SRF electron gun program is supported by DOE Award DE-SC0005264.
SRF electron guns hold out the promise of very bright beams for use in electron injectors, particularly for light source applications such as Free Electron Lasers. The University of Wisconsin is midway in a multi-year program to demonstrate a low frequency electron gun based on a quarter wave resonator cavity. The design includes active tuning and a high temperature superconducting solenoid for emittance compensation. We will report on the status of the 4 MeV SRF electron gun, including the cryomodule, the RF power coupler, the main RF power amplifier/low level RF control system, the photocathode laser system, and the diagnostic beamline. Installation is moving forward in a recently renovated experimental vault adjacent to the existing Aladdin synchrotron. First electron beam is expected in the summer 2012.

MOPPP046

RF Gun Photocathode Research at SLAC

gun, cathode, emittance, electron

664

E.N. Jongewaard, R. Akre, A. Brachmann, W.J. Corbett, S. Gilevich, K. Grouev, P. Hering, P. Krejcik, J.R. Lewandowski, H. Loos, T. M. Montagne, J. Sheppard, P. Stefan, A.E. Vlieks, S.P. Weathersby, F. Zhou
SLAC, Menlo Park, California, USA

Funding: DOE contract DE-AC02-76SF00515.
LCLS is presently operating with a third copper photocathode in the original rf gun, with a quantum efficiency (QE) of ~1x10^-4 and projected emittance eNx,y=0.45 μm at 250 pC bunch charge. The spare LCLS gun is installed in the SLAC Accelerator Structure Test Area (ASTA), processed to the design rf gradient of >120 MV/m. As part of a wider photocathode R&D program, a UV laser system and additional gun diagnostics are being installed at ASTA to measure QE, QE lifetime, and electron beam emittance under a variety of operating conditions. The near-term goals are to test and verify the spare photocathode production/installation sequence, including transfer from the final holding chamber to the rf gun. Mid- and longer-term goals include development of a rigorous understanding of plasma and laser-assisted surface conditioning and investigation of new, high-QE photocathode materials. In parallel, an x-ray photoemission spectroscopy station is nearing completion, to analyze Cu photocathode surface chemistry. In this paper we review the status and anticipated operating parameters of ASTA and the spectroscopy test chamber.

MOPPP074

Magnetic Field Measurement for a THz Undulator Using the Vibrating Wire Method

undulator, electron, radiation, resonance

732

S. Kashiwagi, H. Hama, F. Hinode, M. Kawai, X. Li, T. Muto, K. Nanbu, Y. Tanaka
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan

Funding: This work is supported by the Ministry of Education, Science, Sports and Culture, Grant-in-Aid for Scientific Research (S), Contract #20226003.
We constructed the undulator that is a basically a Halbach planer type for a generation of intense coherent terahertz radiation from the very short electron bunch. The period length of the undulator and the number of periods are 100 mm and 25, respectively. Its maximum magnetic field is 0.41 T and the K-value is 3.82 with 54 mm gap. The vibrating wire method is studied to measure the periodic magnetic field of the undulator. By measuring amplitudes and phases of standing waves excited on the wire by the Lorentz force between AC current and magnetic field, we can reconstruct the magnetic field distribution along the wire. The theoretical analysis has been performed for the THz undulator and derived a relation between a reproducibility of undulator field and the number of the harmonic mode to use for the reconstruction. A model experiment was demonstrated using 20cm wire and one pair of permanent magnet block. The theoretical study and the results of model experiment using the vibrating wire method will be shown in this conference.

MOPPP091

Recent Developments at the DELTA THz Beamline

electron, radiation, storage-ring, undulator

768

P. Ungelenk, M. Bakr, H. Huck, M. Höner, S. Khan, R. Molo, A. Nowaczyk, A. Schick, M. Zeinalzadeh
DELTA, Dortmund, Germany

Funding: Work supported by DFG, BMBF, and by the Federal State NRW.
During 2011, a new dedicated THz beamline has been constructed and commissioned at DELTA, a 1.5 GeV synchrotron light source operated by the TU Dortmund University. This beamline enables extracting and detecting coherent THz pulses caused by a laser-induced density modulation of the electron bunches. Ongoing experiments aim at characterizing the THz radiation as well as investigating the evolution of the density modulation over subsequent revolutions following the initial laser-electron interaction in an undulator.

MOPPR007

Investigation of Techniques for Precise Compton Polarimetry at ELSA

electron, polarization, photon, simulation

783

R. Zimmermann, W. Hillert
ELSA, Bonn, Germany

Funding: Work supported by DFG within SFB/TR16
A Compton polarimeter is currently being installed at the Electron Stretcher Facility ELSA to monitor the degree of polarization of the stored electron beam. For this purpose, circularly polarized light that is emitted by a laser and backscattered off the beam has to be detected. When the polarization of the laser light is switched from left-hand to right-hand circular polarization, the spatial distribution of the backscattered photons is shifted. The extent of this modification is a measure of the beam's polarization degree. Two different experimental techniques that are suitable for a measurement of the effect were compared and evaluated closer through numerical simulations that will be presented in this contribution.

MOPPR016

Femtosecond Level Electron Bunch Diagnostic at Quasi – CW SRF Accelerators: Test Facility ELBE

electron, diagnostics, SRF, photon

810

M. Gensch, C. Kaya, U. Lehnert, P. Michel, Ch. Schneider, W. Seidel
HZDR, Dresden, Germany
G. Geloni
European XFEL GmbH, Hamburg, Germany
M. Helm
FZD, Dresden, Germany
H. Schlarb, A. Shemmary, N. Stojanovic
DESY, Hamburg, Germany

Funding: BMBF through the PIDID proposal and HGF through the ARD initiative
At the srf based prototype cw accelerator ELBE a new electron beamline, providing for femtosecond electron bunches with nC bunch charges and repetition rates in the 1 – 200 KHz regime and with pC bunch charge and repetition rates of 13 MHz is currently constructed. The 40 MeV electrons will be used in photon-electron interaction experiments with TW and PW class laser and the generation of broad band and narrow bandwidth coherent THz pulses. In this paper we outline ideas for novel online diagnostics of the electron bunch properties (e.g. arrival time and bunch form) based on the time and frequency domain analysis of the emitted coherent THz radiation but also based on direct measurements by e.g. electro-optic sampling. The suitability of ELBE as a testbed for diagnostic of future cw X-ray photon sources (e.g. energy recovery linacs) will be discussed.

MOPPR018

Beam Halo Monitor for FLASH and the European XFEL

electron, diagnostics, free-electron-laser, pick-up

816

A. Ignatenko, N. Baboi, O. Hensler, M. Schmitz, K. Wittenburg
DESY, Hamburg, Germany
H.M. Henschel, W. Lange, W. Lohmann
DESY Zeuthen, Zeuthen, Germany
A. Ignatenko
BTU, Cottbus, Germany
S. Schuwalow
Uni HH, Hamburg, Germany

The Beam Halo Monitor for Free-electron Laser in Hamburg (FLASH) based on pCVD diamond and monocrystalline artificial sapphire sensors has been successfully commissioned in September 2009. It is a part of the beam dump diagnostics and ensures safe beam dumping. Its description and the experience gained during its operation are given. The ideas on the design and aspects of operation of the similar systems at FLASH II and the European XFEL are presented.

MOPPR034

A Laser Wire System at Electron Beam Transport Line in BEPCII

electron, photon, positron, simulation

852

C. Zhang, J. Cao, Q.Y. Deng, Y.F. Sui
IHEP, People's Republic of China

Funding: National Natural Science Foundation of China
A Laser Wire system is under development at transport line in BEPCII (Beijing Electron Positron Collider). The structure of whole system is briefly described in this paper. Some work on laser and detector are presented. We also discussed the challenge of Laser Wire and some other things that can affect measurement. According to the plan, the Laser Wire will be installed in electron beam transport line in the summer of 2012.

MOPPR071

Initial Results of Transverse Beam Profile Measurements Using a LYSO:Ce Crystal

radiation, diagnostics, electron, controls

951

A.S. Johnson, A.H. Lumpkin, T.J. Maxwell, J. Ruan, J.K. Santucci, C.C. Tan, R.M. Thurman-Keup, M. Wendt
Fermilab, Batavia, USA

A prototype transverse beam profile monitor for eventual use at the Advanced Superconducting Test Accelerator (ASTA) has been tested at the Fermilab A0 Photoinjector. Results from low-charge (20 pC) studies indicate that a LYSO:Ce scintillator will be a viable replacement for a YAG:Ce scintillator when using intercepting radiation convertor screens for beam profiling. We will also describe the planned implementation of LYSO:Ce crystals to mitigate the coherent optical transition radiation due to the microbunching instability through the use of band-pass filters and specially timed cameras.

MOPPR072

Fermilab PXIE Beam Diagnostics Development and Testing at the HINS Beam Facility

diagnostics, linac, emittance, rfq

954

V.E. Scarpine, B.M. Hanna, V.A. Lebedev, L.R. Prost, A.V. Shemyakin, J. Steimel, M. Wendt
Fermilab, Batavia, USA

Funding: This work was supported by the U.S. Department of Energy under contract No. DE-AC02-07CH11359.
Fermilab is planning the construction of a prototype front end of the Project X linac. The Project X Injector Experiment (PXIE) is expected to accelerate 1 mA cw H⁻ beam up to 30 MeV. Some of the major goals of the project are to test a cw RFQ and H⁻ source, a broadband bunch-by-bunch beam chopper and a low-energy superconducting linac. The successful characterization and operation of such an accelerator places stringent requirements on beam line diagnostics. These crucial beam measurements include bunch currents, beam orbit, beam phase, bunch length, transverse profile and emittance, beam halo and tails, as well as the extinction performance of the broadband chopper. This paper presents PXIE beam measurement requirements and instrumentation development plans. Also presented are plans to test many of these instruments at the Fermilab High Intensity Neutrino Source (HINS) beam facility. Since HINS is already an operational accelerator, utilizing HINS for instrumentation testing allows for quicker development of the required PXIE diagnostics.

MOPPR075

Status of the APEX Beam Diagnostic and First Measurements

diagnostics, cathode, electron, gun

963

D. Filippetto, M.J. Chin, C.W. Cork, S. De Santis, L.R. Doolittle, W.E. Norum, C. F. Papadopoulos, G.J. Portmann, D.G. Quintas, F. Sannibale, R.P. Wells, M.S. Zolotorev
LBNL, Berkeley, California, USA

The APEX project aims to the construction of a high brightness high repetition rate photo-injector at LBNL. In its first phase a 750 keV electron bunch is produced at a maximum repetition rate of 1 MHz, with an adjustable charge per bunch spanning the pC-to-nC region. A load lock system is foreseen to test different cathodes without the need of breaking the vacuum and the downstream diagnostic is used to characterize the photo-emitted beam brightness. In the initial phase the main effort is directed toward the measurement of photocurrent, dark current, thermal emittance and electron beam kinetic energy. In a successive phase, diagnostic for full 6D phase space characterization of space charge dominated beams will be added to the beamline. We report and discuss the present diagnostic beamline layout, first beam measurements and future upgrades.

MOPPR083

Mechanical Design and Evaluation of the MP-11-like Wire Scanner Prototype

controls, linac, vacuum, neutron

984

S. Rodriguez Esparza, J.D. Gilpatrick, M.E. Gruchalla, A.J. Maestas, J.P. Martinez, J.L. Raybun, F.D. Sattler, J.D. Sedillo, B.G. Smith
LANL, Los Alamos, New Mexico, USA

A wire scanner (WS) is a linearly actuated diagnostic device that uses fiber wires (such as Tungsten or Silicon Carbide) to obtain the position and intensity profile of the proton beam at the Los Alamos Neutron Science Center (LANSCE) particle accelerator. LANSCE will be installing approximately 86 new WS in the near future as part of the LANSCE Risk Mitigation project. These 86 new WS include the replacement of many current WS and some newly added to the current linear accelerator and other beam lines. The reason for the replacement and addition of WS is that many of the existing actuators have parts that are no longer readily available and are difficult to find, thus making maintenance very difficult. One of the main goals is to construct the new WS with as many commercially-available-off-the-shelf components as possible. In addition, faster beam scans (both mechanically and in term of data acquisition) are desired for better operation of the accelerator. This document outlines the mechanical design of the new MP-11-like WS prototype and compares it to a previously built and tested SNS-like WS prototype.

TUYB01

Proton Beam Acceleration with Circular Polarized Laser Pulses

proton, electron, plasma, ion

1045

X.Q. Yan, J.E. Chen, C. Lin, Y.R. Lu, H. Wang
PKU/IHIP, Beijing, People's Republic of China
Z.Y. Guo
IHEP, Beijing, People's Republic of China

This presentation should describe the use of circular polarized laser pulses for phase-stable acceleration of proton beams. The principles of the technique should be explained, with comparisons and contrasts made with similar techniques. The potential for production of high-intensity, mono-energetic proton beams should be discussed, and the results of analytical, simulation, and experimental studies presented.

Slides TUYB01 [7.922 MB]

TUYB02

Manufacture and Testing of Optical-scale Accelerator Structures from Silicon and Silica

electron, coupling, acceleration, vacuum

1050

R.J. England, E.R. Colby, R. Laouar, C. McGuinness, B. Montazeri, R.J. Noble, K. Soong, J.E. Spencer, D.R. Walz, Z. Wu
SLAC, Menlo Park, California, USA
R.L. Byer, C.M. Chang, K.J. Leedle, E.A. Peralta
Stanford University, Stanford, California, USA
B.M. Cowan
Tech-X, Boulder, Colorado, USA
M. Qi
Purdue University, West Lafayette, Indiana, USA

We report on recent progress in the design, manufacture and testing of optical-scale accelerator structures made from silicon and silica. The potential of these structures for the development of extremely compact, efficient, and low cost accelerators producing attosecond electron pulses will be discussed, together with various possible applications.

Slides TUYB02 [17.226 MB]

TUOAB01

Timing and Synchronization for the APS Short Pulse X-ray Project

cavity, feedback, LLRF, storage-ring

1077

F. Lenkszus, N.D. Arnold, T.G. Berenc, G. Decker, E.M. Dufresne, R.I. Farnsworth, Y.L. Li, R.M. Lill, H. Ma
ANL, Argonne, USA
J.M. Byrd, L.R. Doolittle, G. Huang, R.B. Wilcox
LBNL, Berkeley, California, USA

Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The Short-Pulse X-ray (SPX) project, which is part of the APS upgrade, will provide intense, tunable, high-repetition-rate picosecond x-ray pulses through the use of deflecting cavities operating at the 8th harmonic of the storage-ring rf. Achieving this picosecond capability while minimizing the impact to other beamlines outside the SPX zone imposes demanding timing and synchronization requirements. For example, the mismatch between the upstream and downstream deflecting cavities' rf field phase is specified to be less than 0.077 degrees root mean squared (rms) at 2815 MHz (~77 femtoseconds). Another stringent requirement is to synchronize beamline pump-probe lasers to the SPX x-ray pulse to 400 femtoseconds rms. To achieve these requirements we have entered into a collaboration with the Beam Technology group at LBNL. They have developed and demonstrated a system for distributing stable rf signals over optical fiber capable of achieving less than 20 femtoseconds rms drift and jitter over 2.2 km over 60 hours*. This paper defines the overall timing/synchronization requirements for the SPX and describes the plan to achieve them.
* R. Wilcox et al. Opt. Let. 34(20), Oct 15, 2009

Slides TUOAB01 [2.515 MB]

TUOBB01

A European Proposal for the Compton Gamma-ray Source of ELI-NP

photon, electron, emittance, scattering

1086

L. Serafini, I. Boscolo, F. Broggi, V. Petrillo
Istituto Nazionale di Fisica Nucleare, Milano, Italy
O. Adriani, G. Graziani, G. Passaleva
INFN-FI, Sesto Fiorentino, Italy
S. Albergo, A. Tricomi
INFN-CT, Catania, Italy
D. Alesini, M.P. Anania, A. Bacci, R. Bedogni, M. Bellaveglia, C. Biscari, R. Boni, M. Boscolo, M. Castellano, E. Chiadroni, A. Clozza, E. Di Pasquale, G. Di Pirro, A. Drago, A. Esposito, M. Ferrario, A. Gallo, G. Gatti, A. Ghigo, F. Marcellini, C. Maroli, G. Mazzitelli, E. Pace, L. Pellegrino, R. Ricci, M. Serio, F. Sgamma, B. Spataro, A. Stecchi, A. Stella, P. Tomassini, C. Vaccarezza, S. Vescovi, F. Villa
INFN/LNF, Frascati (Roma), Italy
D. Angal-Kalinin, J.A. Clarke, B.D. Fell, A.R. Goulden, J.D. Herbert, S.P. Jamison, P.A. McIntosh, R.J. Smith, S.L. Smith
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
P. Antici, M. Coppola, L. Lancia, A. Mostacci, L. Palumbo
URLS, Rome, Italy
N. Bliss, B.G. Martlew
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
P. Cardarelli, M. Gambaccini
INFN-Ferrara, Ferrara, Italy
L. Catani, A. Cianchi
INFN-Roma II, Roma, Italy
I. Chaikovska, O. Dadoun, A. Stocchi, A. Variola, Z.F. Zomer
LAL, Orsay, France
C. De Martinis
INFN/LASA, Segrate (MI), Italy
F. Druon, P. Fichot
ILE, Palaiseau Cedex, France
E. Iarocci
University of Rome "La Sapienza", Rome, Italy
M. Migliorati
Rome University La Sapienza, Roma, Italy
A.-S. Müller
IN2P3, Paris, France
V. Nardone
Università di Roma I La Sapienza, Roma, Italy
C. Ronsivalle
ENEA C.R. Frascati, Frascati (Roma), Italy
M. Veltri
Uniurb, Urbino (PU), Italy

A European proposal is under preparation for the Compton gamma-ray Source of ELI-NP. In the Romanian pillar of ELI (the European Extreme Light Infrastructure) an advanced gamma-ray beam is foreseen, coupled to two 10 PW laser systems. The photons will be generated by Compton back-scattering in the collision between a high quality electron beam and a high power laser. A European collaboration formed by INFN, Univ. of Roma La Sapienza, Orsay-LAL of IN2P3, Univ. de Paris Sud XI and ASTeC at Daresbury, is preparing a TDR exploring the feasibility of a machine expected to achieve the Gamma-ray beam specifications: energy tunable between 1 and 20 MeV, narrow bandwidth (0.3%) and high spectral density, 10⁴ photons/sec/eV. We will describe the lay-out of the 720 MeV RF Linac and the collision laser with the associated optical cavity, as well as the optimized beam dynamics to achieve maximum phase space density at the collision, taking into account beam loading and beam break-up due to the acceleration of long bunch trains. The predicted gamma-ray spectra will be evaluated as the gamma photons collimators background. An option for electron bunches recirculation will also be illustrated.

Slides TUOBB01 [5.099 MB]

TUOBB03

Status of the FERMI@Elettra Project

FEL, electron, radiation, photon

1092

M. Svandrlik, E. Allaria, L. Badano, S. Bassanese, F. Bencivenga, E. Busetto, C. Callegari, F. Capotondi, D. Castronovo, M. Coreno, P. Craievich, I. Cudin, G. D'Auria, M. Dal Forno, M.B. Danailov, R. De Monte, G. De Ninno, A.A. Demidovich, M. Di Fraia, S. Di Mitri, B. Diviacco, A. Fabris, R. Fabris, W.M. Fawley, M. Ferianis, E. Ferrari, L. Fröhlich, P. Furlan Radivo, G. Gaio, L. Giannessi, R. Gobessi, C. Grazioli, E. Karantzoulis, M. Kiskinova, M. Lonza, B. Mahieu, C. Masciovecchio, S. Noè, F. Parmigiani, G. Penco, E. Principi, F. Rossi, L. Rumiz, C. Scafuri, S. Spampinati, C. Spezzani, C. Svetina, M. Trovò, A. Vascotto, M. Veronese, R. Visintini, M. Zaccaria, D. Zangrando, M. Zangrando
ELETTRA, Basovizza, Italy

Funding: The work was supported in part by the Italian Ministry of University and Research under grants FIRB-RBAP045JF2 and FIRB-RBAP06AWK3.
The FERMI@Elettra seeded Free Electron Laser has provided the first photons to the experimental stations during 2011. The first FEL line in operation is FEL-1, covering the wavelength range between 100 nm and 20 nm. The facility will be opened to users by the end of 2012. In the meantime the installation of the second FEL line, FEL-2 covering the higher energy range down to 4 nm, is progressing on schedule and first tests have started. A description of the status of the project is presented here.

Slides TUOBB03 [5.316 MB]

TUEPPB010

Oscillator Seeding of a High Gain Harmonic Generation FEL in a Radiator-first Configuration

FEL, electron, radiation, bunching

1137

P.R. Gandhi, J.S. Wurtele
UCB, Berkeley, California, USA
G. Penn, M.W. Reinsch
LBNL, Berkeley, California, USA

A longitudinally coherent X-ray pulse from a high repetition rate free electron laser (FEL) is desired for a wide variety of experimental applications. However, generating such a pulse with a repetition rate greater than ~1 MHz is a significant challenge. The desired high rep rate sources, primarily high harmonic generation with intense lasers in gases or plasmas, do not exist now, and, for the multi-MHz bunch trains that superconducting accelerators can potentially produce, are likely not feasible with current technology. In this paper, we propose to place an oscillator downstream of a radiator. The oscillator generates radiation that is used as a seed for a high gain harmonic generation (HGHG) FEL which is upstream of the oscillator. For the first few pulses the oscillator builds up power and, until power is built up, the radiator has no HGHG seed. As power in the oscillator saturates, the HGHG is seeded and power is produced. The dynamics and stability of this radiator-first scheme is explored analytically and numerically. A single-pass map is derived using a semi-analytic model for FEL gain and saturation. Iteration of the map is shown to be in good agreement with simulations.

TUEPPB011

Echo Enabled High Mode Generation for X-ray FELs

electron, bunching, FEL, free-electron-laser

1140

E. Hemsing
SLAC, Menlo Park, California, USA
A. Marinelli
UCLA, Los Angeles, California, USA

Funding: Work supported by U.S. DOE under Contract Nos. DE-AC02-76SF00515 and DE-FG02-07ER46272.
We describe a simple technique based on a modified echo-enabled harmonic generation (EEHG) scheme to manipulate the three-dimensional electron beam microbunching distribution in order to generate higher-order optical modes in an FEL. As with EEHG, the concept uses two modulators and two chicanes to produce microbunching. However, in one of the modulators, the resonant interaction with the laser has a well-defined transverse structure that becomes strongly correlated to the longitudinal microbunching distribution. Both high-harmonic frequencies and high transverse mode numbers can be generated through a transversely-dependent echo effect.

TUEPPB015

Generation of Narrow-Band Coherent Tunable Terahertz Radiation using a Laser-Modulated Electron Beam

electron, radiation, undulator, bunching

1146

M.P. Dunning, C. Hast, E. Hemsing, R.K. Jobe, D.J. McCormick, J. Nelson, T.O. Raubenheimer, K. Soong, Z.M. Szalata, D.R. Walz, S.P. Weathersby, D. Xiang
SLAC, Menlo Park, California, USA

Funding: Work supported by US DOE contract DE-AC02-76SF00515.
The technical layout and initial results of an experiment to generate narrow-band, coherent, tunable terahertz (THz) radiation through the down-conversion of the frequency of optical lasers using a laser-modulated electron beam are described. In this experiment a 120 MeV electron beam is first energy modulated by two lasers with different wavelengths. After passing through a dispersive section, the energy modulation is converted into a density modulation at THz frequencies. This density-modulated beam will be used to generate narrow-band THz radiation using a coherent transition radiator inserted into the beam path. The central frequency of the THz radiation can be tuned by varying the wavelength of one of the two lasers or the energy chirp of the electron beam. The experiment is being performed at the NLCTA at SLAC, and will utilize the existing Echo-7 beamline, where echo-enabled harmonic generation (EEHG) was recently demonstrated.

TUPPC094

Experimental Observations of Large-amplitude Solitary Waves in Electron Beams

space-charge, electron, longitudinal-dynamics, gun

1377

Y. Mo, B.L. Beaudoin, D.W. Feldman, I. Haber, R.A. Kishek, P.G. O'Shea
UMD, College Park, Maryland, USA
J.C.T. Thangaraj
Fermilab, Batavia, USA

Funding: Work funded by the US Dept. of Energy Offices of Fusion Energy Sciences and High Energy Physics and Fusion Energy Sciences, and by the Dept. of Defense Office of Naval Research.
The longitudinal dynamics of space charge dominated beams plays an important role in particle accelerators and other applications such as heavy ion fusion and free electron lasers (FELs). All beams are space-charge dominated near the source. Furthermore, the longitudinal profile is not necessarily an ideal mathematical function. By means of experiments on the University of Maryland Electron Ring (UMER), we studied how a perturbation to the line charge density could affect the beam propagation. By varying the initial amplitude of the perturbation, we access nonlinear space charge physics. When starting with large-amplitude perturbations, we have observed, for the first time in charged particle beams, solitary waves for which the nonlinear steepening exactly balances the wave dispersion, leading to persistent waves that preserves their shape over a long distance. This paper presents the results of the soliton experiments, including systematic studies of the dependence of the soliton propagation on beam current, perturbation level and width. The data is compared with theory and simulation.

TUPPD023

RFQ LINAC Commissioning and Carbon⁴⁺ Acceleration for Ag¹⁵⁺ Acceleration via Direct Plasma Injection Scheme

ion, rfq, plasma, linac

1458

T. Yamamoto, M. Washio
RISE, Tokyo, Japan
K. Kondo, M. Okamura, M. Sekine
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.
High intensity, high charge state, various ion species and small emittance heavy ion beam is required for particle physics, medical uses, inertial fusion, and a simulator of space radiation. Direct Plasma Injection Scheme (DPIS), the way to make laser abrasion plasma developed in the past several years, is used for Heavy Ion beam Accerelation. High density plasma with an initial drift velocity will fly to the entrance of the Radio Frequency Quadropole (RFQ) LINAC; ions will be separated from plasma via high voltage and injected it to RFQ LINAC directly. After RFQ LINAC, ions accepted to the RF buckets are accelerated to a current of over 10mA. Until now, we tried a carbon target using the partial modulation rod of the RFQ LINAC, and succeeded in accelerating carbon⁴⁺, carbon⁵⁺, and carbon⁶⁺ non-bunched beam.* In this instance, we succeeded in commissioning of new full modulation RFQ rod designed for the charge mass ratio(q/A) 1/6. We tested the acceleration of carbon⁴⁺, and it could be catched by the RF bucket and accelerated. After this, we'll try accelerating carbon²⁺ (q/A=1/6) for demonstrating the feasibility of the Ag¹⁵⁺ ion accelerating.
* T. Kanesue, M. Okamura, K. Kondo, J. Tamura, H. Kashiwagi, Z. Zhang, Drift distance survey in direct plasma injection scheme for high current beam production, Rev Sci Instrum. 2010 Feb;81(2):02B723

TUPPD034

Multi-bunch Beam Generation by Photo-cathode RF Gun for KEK-STF

cavity, gun, cathode, electron

1479

M. Kuriki, S. Hosoda, H. Iijima
HU/AdSM, Higashi-Hiroshima, Japan
A. Ayaka
Sokendai, Ibaraki, Japan
H. Hayano, J. Urakawa, K. Watanabe
KEK, Ibaraki, Japan
G. Isoyama, R. Kato, K. Kawase
ISIR, Osaka, Japan
S. Kashiwagi
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
K. Sakaue
RISE, Tokyo, Japan

Funding: MEXT, Quantum beam project.
KEK-STF is doing R&D of Super-Conducting (SC) accelerator technology for ILC (International Linear Collider), based on 1.3 GHz RF system. For STF and ILC, the pulse length is 1ms and the repetition is 5Hz. We developed a L-band Normal-Conducting RF gun designed by DESY to provide electron beam over such long pulse duration. For NC Photo-cathode RF gun, such high duty and long pulse operation is a challenging task, because the detuning by the heat load of cavity dissipation power is significant. The RF gun provides the electron pulse train to SC accelerator modules which will be operated at 31.5 MV/m gradient. Precise RF control is essential for SC accelerator because the beam loading and input RF power should be well ballanced for a stable operation. The beam test to demonstrate the stable opeation is very important for SC accelerator R&D. The system is also used to demonstrate high-flux quasi-monochromatic X-ray generation by inverse Compton scattering at KEK-STF. The experiment is carried out from April 2012 to November 2012 at KEK-STF. We report the latest status of the multi-bunch generation by the RF gun.

TUPPD037

Simulation Study of the Effect of the Proton Layer Thickness on TNSA

electron, plasma, proton, simulation

1488

L. Lecz
TEMF, TU Darmstadt, Darmstadt, Germany
O. Boine-Frankenheim, V. Kornilov
GSI, Darmstadt, Germany

The LIGHT project is a collaboration of several laser and accelerator laboratories in Germany with the purpose to consolidate the theoretical, numerical and experimental investigations for the usage of laser accelerated ions in the conventional accelerators. The central facility is the PHELIX laser at GSI, Darmstadt, with a strong-field solenoid as a collimation and transport device. This contribution is devoted to the numerical investigation of the proton acceleration via the TNSA mechanism using 1D and 2D particle-in-cell electro-magnetic simulations. The phase-space distribution of the accelerated protons and co-moving electrons, which is necessary for further transport studies, is investigated for different parameters of the thin hydrogen-rich contamination layer on the rear target surface. Depending on the layer thickness the protons can be accelerated in different regimes, from the quasi-static acceleration for mono-layers up to the isothermal plasma expansion for thick layers.

TUPPD044

Conceptual Gas Jet as a Stripping Target for Charge Exchange Injection

target, injection, ion, proton

1500

V.G. Dudnikov, C.M. Ankenbrandt
Muons, Inc, Batavia, USA

Stripping targets for charge exchange injection now uses thin carbon or Al2O3 foils. During long time injection for high intense beam accumulation by low current injection a foil life time can be compromised by overheating and alternative stripping targets need be developed. A pulsed supersonic gas jet was used as a stripping target in first realization of charge exchange injection with H⁻ ion energy 1.5 MeV and stationary gas jets are used as internal targets in experiments with super high vacuum. A stripper target thickness is proportional to the injection energy and for energy 1GeV should be ~0.3 mg/cm² of carbon. The pulsed gas target with such thickness acceptable for long time charge exchange injection can be produced with using of heavy hydrocarbon molecules used in the diffusion or booster vacuum pumps. Formation of the pulsed gas jet stripping targets will be considered.

TUPPD050

Investigation of Laser-cleaning Process on Lead Photocathodes

electron, cathode, photon, high-voltage

1515

S.G. Schubert, R. Barday, T. Kamps, T. Quast, A. Varykhalov
HZB, Berlin, Germany
R. Nietubyć
The Andrzej Soltan Institute for Nuclear Studies, Centre Świerk, Świerk/Otwock, Poland
F. Siewert
BESSY GmbH, Berlin, Germany
J. Smedley
BNL, Upton, Long Island, New York, USA
G. Weinberg
FHI, Berlin, Germany

Funding: Work supported by Bundesministerium für Bildung und Forschung and Land Berlin.
Metal photocathodes are widely used in electron injectors due to their stability and long life time; unfortunately they exhibit low quantum efficiency. Due to adsorption of contaminants the work function increases and thus the quantum efficiency is further reduced. In order to increase the quantum efficiency of our Pb cathode we performed a cleaning procedure by means of a high power excimer laser as suggested by Smedley*. The process was studied on witness samples in a combined photo emission, SEM and quantum efficiency measurement study. Thin Lead films were arc-deposited on optical polished Mo-substrates**. Before and after irradiation the sample was analyzed at 140 eV photon energy at a XPS/ARPES end station at the synchrotron radiation source Bessy II. We followed the change of the Pb 5d signals. In the initial situation we observed signals originating from metallic Pb and Pb in the oxidized state, respectively. Since the surface roughness is of concern for the injector performance it was examined before and after the irradiation procedure with white-light-interferometry and the surface morphology by means of SEM.
*J. Smedley et al, PRST-AB 11, 013502 (2008).
** Rao, T. et al., IPAC 2010, THPEC020 (2010).

TUPPD051

Operational Experience with the Nb/Pb SRF Photoelectron Gun

emittance, cathode, solenoid, cavity

1518

T. Kamps, W. Anders, R. Barday, A. Jankowiak, J. Knobloch, O. Kugeler, A.N. Matveenko, A. Neumann, T. Quast, J. Rudolph, S.G. Schubert, J. Völker
HZB, Berlin, Germany
P. Kneisel
JLAB, Newport News, Virginia, USA
R. Nietubyć
The Andrzej Soltan Institute for Nuclear Studies, Centre Świerk, Świerk/Otwock, Poland
J.K. Sekutowicz
DESY, Hamburg, Germany
J. Smedley
BNL, Upton, Long Island, New York, USA
J. Teichert
HZDR, Dresden, Germany
V. Volkov
BINP SB RAS, Novosibirsk, Russia
I. Will
MBI, Berlin, Germany

SRF photoelectron guns offer the promise of high brightness, high average current beam production for the next generation of accelerator driven light sources such as free electron lasers, THz radiation sources or energy-recovery linac driven synchrotron radiation sources. In a first step a fully superconducting RF (SRF) photoelectron gun is under development by a collaboration between HZB, DESY, JLAB, BNL and NCBJ. The aim of the experiment is to understand and improve the performance of a Nb SRF gun cavity coated with a small metallic Pb cathode film on the cavity backplane. This paper describes the highlights from the commissioning and beam parameter measurements. The main focus is on lessons learned from operation of the SRF gun.

TUPPD052

A New Load Lock System for the Source of Polarized Electrons at ELSA

electron, vacuum, polarization, ion

1521

D. Heiliger, W. Hillert, B. Neff
ELSA, Bonn, Germany

Funding: supported by DFG (SFB/TR16)
Since 2000, an inverted source of polarized electrons at the electron stretcher accelerator ELSA routinely provides a pulsed beam with a current of 100 mA and a polarization degree of about 80%. One micro-second long pulses with 100 nC charge are produced by irradiating a GaAs strained-layer superlattice photocathode (8 mm in diameter) with laser light. Future accelerator operation requires a significantly higher beam intensity, which can be achieved by using photocathodes with sufficiently high quantum efficiency. Therefore, and in order to enhance the reliability and up time of the source, a new extreme high-vacuum (XHV) load lock system was installed and commissioned at the beginning of this year. It consists of three chambers: The activation chamber for heat cleaning of the photocathodes and activation with cesium and oxygen. The storage chamber in which up to five different types of photocathodes with various diameters of the emitting surface can be stored under XHV conditions. The loading chamber in which an atomic hydrogen source is used to remove any remaining surface oxidation. Additionally, tests of the photocathodes’ properties can be performed during operation.

TUPPD055

Characterization of ps-spaced Comb Beams at SPARC

simulation, linac, radiation, bunching

1527

A. Mostacci
URLS, Rome, Italy
A. Bacci, A.R. Rossi
Istituto Nazionale di Fisica Nucleare, Milano, Italy
M. Bellaveglia, E. Chiadroni, G. Di Pirro, M. Ferrario, G. Gatti, C. Vaccarezza
INFN/LNF, Frascati (Roma), Italy
A. Cianchi
Università di Roma II Tor Vergata, Roma, Italy
C. Ronsivalle
ENEA C.R. Frascati, Frascati (Roma), Italy

SPARC in Frascati is a high brightness photo-injector used to explore advanced beam manipulation techniques. Sub-picosecond, high brightness electron bunch trains (the so called comb beam) can be generated illuminating the cathode of a RF photoinjector with a laser pulse train and via velocity bunching technique. In this paper different aspects of the physics of this advanced beam manipulation technique are discussed combining simulation and measurements. Beam dynamics numerical macroparticle simulations have been compared with the experimental results for model validation; they allow to gain insights on the beam evolution highlighting several aspects which can not be measured. In particular, we focus on the train evolution in the linac sections and in the dog-leg line up to the THz station and on the effective rms length of the single pulses within the train when it becomes shorter than the resolution.

TUPPD056

Development of a Photo-injector Laser System for KEK ERL Test Accelerator

cavity, cathode, controls, alignment

1530

Y. Honda
KEK, Ibaraki, Japan

As a test accelerator for future light source, Compact Energy Recovery Linac has been constructed in KEK. For its photo-injector, we have been developing a laser system. It requires high repetition rate and high average power at a visible wavelength. Development of an high power fiber amplifier and high efficiency wavelength conversion system utilizing an optical cavity will be reported.

TUPPD057

High Charge Low Emittance RF Gun for SuperKEKB

gun, cathode, emittance, injection

1533

T. Natsui, Y. Ogawa, M. Yoshida, X. Zhou
KEK, Ibaraki, Japan

We are developing a new RF gun for SuperKEKB. We are upgrading KEKB to SuperKEKB now. High charge low emittance electron and positron beams are required for SuperKEKB. We will generate 7.0 GeV electron beam at 5 nC 20 mm-mrad by J-linac. In this linac, a photo cathode S-band RF gun will be used as the electron beam source. For this reason, we are developing an advanced RF gun. Now, we are testing a Disk and Washer (DAW) type RF gun. Its photo cathode material is LaB6. Normally, LaB6 is used as a thermionic cathode, but it is suitable for　long-life photo cathode operation. This gun has a strong focusing field at the cathode and the acceleration field distribution also has a focusing effect. We will obtain 3.2 MeV beam energy with the gun. The design of RF gun and experimental results will be shown.

TUPPD061

High-Power RF Test of an RF-Gun for PAL-XFEL

gun, emittance, electron, injection

1539

J.H. Hong, J.H. Han, H.-S. Kang, C. Kim, S.H. Kim, C.-K. Min, S.S. Park, S.J. Park, Y.J. Park
PAL, Pohang, Kyungbuk, Republic of Korea
M.S. Chae, I.S. Ko, Y.W. Parc
POSTECH, Pohang, Kyungbuk, Republic of Korea

A photocathode RF-gun for the X-ray free electron laser (XFEL) at the Pohang Accelerator Laboratory (PAL) has been fabricated and tested at PAL. This RF-gun is based on a 1.6-cell cavity with dual-feed waveguide ports and two pumping ports. The RF gun was designed by PAL and POSTECH. The RF-gun has been successfully tested with a cathode electric field gradient up to 126MV/m at a repetition rate of 30 Hz. This paper reports the recent results on the beam test of the RF-gun with high power RF at the gun test facility. We present and discuss the measurements of the basic beam parameters such as charge, energy, energy spread, and transverse emittance.

TUPPD062

The Source of Emittance Dilution and photoemission tunneling effect in Photocathode RF Guns

cathode, emittance, cavity, simulation

1542

V. Volkov
BINP SB RAS, Novosibirsk, Russia
R. Barday, T. Kamps, J. Knobloch, A.N. Matveenko, S.G. Schubert, J. Völker
HZB, Berlin, Germany
J.K. Sekutowicz
DESY, Hamburg, Germany

Funding: Work supported by Bundesministerium für Bildung und Forschung, Land Berlin, and grants of Helmholtz Association VH-NG-636 and HRJRG-214.
Experimental data on HoBiCaT SRF photoinjector give an emittance which is much larger than the predicted thermal emittance. Modeling of photocathode RF gun beams with the different imperfections of experimental setup (alignment errors, inhomogeneity of quantum efficiency and laser power distributions on the cathode) is given. The main reason for the beam emittance dilution is photocathode field imperfections induced by field emitters that change the local electric field. Some field models of such photocathodes are tested in the simulations. The dependence of photocathode beam currents on the surface electric field was measured with the HoBiCaT SRF Photoinjector. The dependence can be explained by the tunneling effect described by Fowler-Nordheim like equation and is difficult to explain by usually applying Schottky effect.

TUPPD066

Lifetime Studies of Cs2Te Cathodes at the PHIN RF Photoinjector at CERN

vacuum, cathode, gun, beam-losses

1554

C. Heßler, E. Chevallay, M. Divall Csatari, S. Döbert, V. Fedosseev
CERN, Geneva, Switzerland

The PHIN photoinjector has been developed to study the feasibility of a photoinjector option for the CLIC (Compact LInear Collider) drive beam as an alternative to the baseline design, using a thermionic gun. The CLIC drive beam requires a high charge of 8.4 nC per bunch in 0.14 ms long trains, with 500 MHz bunch spacing and 50 Hz macro pulse repetition rate, which corresponds to a total charge per macro pulse of 0.59 mC. This means unusually high peak and average currents for photoinjectors and is challenging with respect to the cathode lifetime. In this paper detailed studies of the lifetime of Cs2Te cathodes, produced by the co-evaporation technique, with respect to bunch charge, train length and vacuum level are presented. Furthermore, the impact of the train length and bunch charge on the vacuum level will be discussed and steps to extend the lifetime will be outlined.

TUPPD067

Experimental Facility for Measuring the Electron Energy Distribution from Photocathodes

electron, cathode, vacuum, brightness

1557

L.B. Jones, R.J. Cash, B.D. Fell, J.W. McKenzie, K.J. Middleman, B.L. Militsyn
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
H.E. Scheibler, A.S. Terekhov
ISP, Novosibirsk, Russia

ASTeC have spent several years developing a GaAs Photocathode Preparation Facility (PPF) which routinely produces cathodes with quantum efficiencies (Q.E.) up to 20% at 635 nm*. The goal is to use these cathodes in high-average-current high-brightness injectors for particle accelerators. Electron injector brightness is driven by photocathode emittance, and brightness will be increased significantly by reducing the longitudinal and transverse energy spread. We are constructing an experimental system for measurement of the horizontal and transverse energy spreads at room and LN₂-temperature which accepts photocathodes from the PPF. The sample will be illuminated by a small, variable-wavelength light spot. The beam image will be projected onto a detector comprised of 3 grids which act as an energy filter, a micro-channel plate and a phosphor screen. A low-noise CCD camera will capture screen images, and the electron distribution and energy spread will be extracted through analysis of these images as a function of the grid potentials. The system will include a leak valve to progressively degrade the cathode, and thus allow its properties to be measured as a function of Q.E.
* Proc IPAC ’11, THPC129 (2011).

TUPPD068

Design of the Production and Measurement of Ultra-Short Electron Bunches from an S-band RF Photoinjector

cavity, gun, dipole, electron

1560

J.W. McKenzie, D. Angal-Kalinin, J.K. Jones, B.L. Militsyn
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

The Electron Beam Test Facility (EBTF) is planned for installation in late 2012 at Daresbury Laboratory. An S-band RF photoinjector provides ultrashort, low emittance electron bunches up to 6 MeV. A suite of diagnostics has been designed to fully characterise the bunches. A particular focus has been on producing and measuring bunch lengths less than 100 fs. This can be achieved with a multi-cell standing wave S-band transverse deflecting cavity. Operating such a cavity with low energy electrons provides certain challenges which are discussed in this paper with respect to beam dynamic simulations.

TUPPD069

Schottky-Enabled Photoemission and Dark Current Measurements - Toward an Alternate Approach to Fowler-Nordheim Plot Analysis

gun, site, photon, cathode

1563

E.E. Wisniewski, W. Gai, J.G. Power
ANL, Argonne, USA
H. Chen, Y.-C. Du, Hua, J.F. Hua, W.-H. Huang, C.-X. Tang, L.X. Yan, Y. You
TUB, Beijing, People's Republic of China
A. Grudiev, W. Wuensch
CERN, Geneva, Switzerland
E.E. Wisniewski
Illinois Institute of Technology, Chicago, Illinois, USA

Field-emitted dark current, a major gradient-limiting factor in RF cavities, is usually analyzed via Fowler-Nordheim (FN) plots. Traditionally, field emission is attributed to geometrical perturbations on the bulk surface whose field enhancement factor (beta) and the emitting area (A) can be extracted from the FN plot. Field enhancement factors extracted in this way are typically much too high (1 to 2 orders of magnitude) to be explainable by either the geometric projection model applied to the measured surface roughness or by field enhancement factors extracted from Schottky-enabled photoemission measurements. We compare traditional analysis of FN plots to an alternate approach employing local work function variation. This is illustrated by comparative analysis of recent dark current and Schottky-enabled photoemission data taken at Tsinghua S-band RF gun. We conclude by describing a possible experimental plan for discrimination of variation of local work function vs. local field enhancement.

TUPPD076

Photocathode Studies for the SPEAR3 Injector RF Gun

cathode, linac, gun, klystron

1575

S. Park, W.J. Corbett, S.M. Gierman, J.R. Maldonado
SLAC, Menlo Park, California, USA

Funding: Work supported by U.S. Department of Energy Contract DE-AC03- 76SF00515 and Office of Basic Energy Sciences, Division of Chemical Sciences.
The electron gun for the SPEAR3 injector operates with a warm thermionic dispenser cathode immersed in a 1.5-cell RF structure. At each injection cycle the gun accelerates several thousand electron bunches up to ~3 MeV during a 2.5us rf pulse. The individual bunches are then compressed by an alpha magnet and a traveling-wave chopper selects 3-5 bunches so they don’t cause beam loading to the linac, where the accelerated bunches reach 120 MeV for subsequent capture in a single booster synchrotron bucket. Tests are underway to operate the dispenser cathode as a cold electron photo-emitter driven by an external laser system. Eventually, without the copper, this will enable multi-bunch injections to the Booster and SPEAR3. In parallel, tests are underway to evaluate quantum efficiency and beam emittance for a beam emitted from a CsBr photocathode with ns- and ps-pulses of UV laser light. In this paper we report on both the cold cathode electron gun operation studies for SPEAR3 and the CsBr research aimed at developing advanced cathode materials for future applications.

TUPPD079

Design of an L-Band RF Photoinjector for the Idaho Accelerator Center 44 MeV Linac

linac, emittance, gun, solenoid

1584

M. Titberidze, A.W. Hunt, D.P. Wells
IAC, Pocatello, IDAHO, USA
Y. Kim
ISU, Pocatello, Idaho, USA

At the Idaho Accelerator Center (IAC) of Idaho State University, we have been operating a 44 MeV L-band RF (1300 MHz) linear accelerator (LINAC) for various user applications such as medical isotope production, Laser Compton Scattering (LCS), positron annihilation energy spectroscopy, and photo fission. But the LINAC is not optimized properly to supply high quality electron beam for those experiments due to limitations of an existing 85 kV thermionic DC gun. In the near future, we are planning to use the L-band LINAC for new user applications such as Accelerator Driven subcritical nuclear reactor System (ADS), photon tagging facility, Ultrafast Electron Diffraction (UED) facility, and high power coherent Terahertz light source facility. Therefore, recently, we have been studying a future upgrade of the L-band LINAC with an RF photoinjector using ASTRA code. In this paper, we describe ASTRA simulation results and a new layout of the L-band LINAC, which is based on an L-band 1.5 cell RF photoinjector. Then, we describe its expected performance for two different single bunch charges (1 nC and 5 nC).

TUPPD080

Design of Ultrafast High-Brightness Electron Source

cathode, electron, gun, brightness

1587

J.H. Park, H. Bluem, J. Rathke, T. Schultheiss, A.M.M. Todd
AES, Princeton, New Jersey, USA

Funding: This work was supported by the U.S. Department of Energy, under Contract No. DE-SC0006210.
Generation and preservation of ultrafast electron beams is one of the major challenges in accelerator R&D. Space charge forces play a fundamental role in emittance dilution and bunch lengthening for all high brightness beams. In order to generate and preserve the ultrafast high-brightness electron beam, transverse and longitudinal space charge effects have to be considered. Several approaches to achieving ultra-short bunches have been explored such as velocity bunching and magnetic compression. However, each option suffers drawbacks in achieving a compact ultrafast high-brightness source. We present an alternative scheme to achieve an ultrafast high-brightness electron beam using a radial bunch compression technique in an x-band photocathode RF electron gun. By compensating the path length difference with a curved cathode and using an extremely high acceleration gradient (greater than 200 MV/m), we seek to deliver 100 pC, 100 fsec bunches.

TUPPP005

LUNEX5: A French FEL Test Facility Light Source Proposal

FEL, emittance, electron, undulator

1611

A. Loulergue, C. Benabderrahmane, M. Bessière, P. Betinelli-Deck, F. Bouvet, A. Buteau, L. Cassinari, M.-E. Couprie, J. Daillant, J.-C. Denard, P. Eymard, B. Gagey, C. Herbeaux, M. Labat, A. Lestrade, P. Marchand, J.L. Marlats, C. Miron, P. Morin, A. Nadji, F. Polack, J.B. Pruvost, F. Ribeiro, J.P. Ricaud, P. Roy
SOLEIL, Gif-sur-Yvette, France
S. Bielawski, C. Evain, C. Szwaj
PhLAM/CERCLA, Villeneuve d'Ascq Cedex, France
B. Carré
CEA/DSM/DRECAM/SPAM, Gif-sur-Yvette, France
G. Devanz, M. Luong
CEA/DSM/IRFU, France
L. Farvacque, G. Lebec
ESRF, Grenoble, France
G. Lambert, A. Lifschitz, V. Malka, A. Rousse
LOA, Palaiseau, France
M. Le Parquier
CERLA, Villeneuve d'Ascq, France
J. Lüning
CCPMR, Paris, France
R. Roux
LAL, Orsay, France

LUNEX5 is a new synchrotron FEL source project aiming at delivering short and coherent X-ray pulses to probe ultrafast phenomena at the femto-second scale, to investigate extremely low density samples as well as to image individual nm scale objects. The proposed machine layout is based on a 400 MeV super-conducting Conventional Linear Accelerator (CLA) mainly composed of 2 XFEL type cryo-modules together with a normal-conducting high brightness photo RF gun. This present mature and reliable technology is able to deliver high quality electron bunches up to few kHz suitable for user experiments. Further more, the last decade improvement in synchronization and stability offer a fertile land to explore the different and innovative seeded FEL operations aiming at producing higher coherence and energetic X-rays for the pilot user full benefits. In parallel of the CLA branch, the very promising and highly innovative Laser Wake-Field Accelerator (LWFA) able to produce very short electron bunches in the range of the femto-second and high peak current up to few GeV is foreseen as a FEL bench test using the same undulator lines.

TUPPP008

Recent Results From the Short-Pulse Facility at the DELTA Storage Ring

radiation, electron, undulator, synchrotron

1617

A. Schick, M. Bakr, H. Huck, M. Höner, S. Khan, R. Molo, A. Nowaczyk, P. Ungelenk, M. Zeinalzadeh
DELTA, Dortmund, Germany

Funding: Work supported by DFG, BMBF and by the Federal State NRW.
At the 1.5 GeV synchrotron light source DELTA, operated by the TU Dortmund University, a new facility for ultrashort pulses in the VUV and THz regime is currently under commissioning. Here, the interaction of an intense, ultrashort laser pulse, co-propagating with the electrons in an optical klystron, leads to coherent synchrotron radiation at harmonics of the incident laser wavelength. The aim of the present commissioning steps is to extend the emitted wavelength down to about 50 nm, enabling femtosecond-resolved pump-probe experiments in the VUV regime. Other issues include increasing the photon flux by optimizing the laser-electron interaction and improving the stability and ease of operation of the source.

TUPPP012

Optimization of the Beam Optical Parameters of the Linac-based Terahertz Source FLUTE

gun, space-charge, linac, simulation

1629

S. Naknaimueang, E. Huttel, A.-S. Müller, M.J. Nasse, R. Rossmanith, M. Schuh, M. Schwarz, P. Wesolowski
KIT, Karlsruhe, Germany
M.T. Schmelling
MPI-K, Heidelberg, Germany

Funding: Karlsruher Institut für Technologie.
FLUTE is a compact accelerator (consisting of a 7 MeV laser gun, a 50 MeV linac, and bunch compressors) under construction at KIT in Karlsruhe for producing coherent THz radiation. The programs ASTRA and CSRtrack were used to optimize the beam parameters. The aim was to minimize the bunch length used in various THz experiments, with bunch charges between 100 pC and 3 nC. It was calculated that the bunch length after compression depends both on the bunch current and the transverse beam size. The transverse beam size depends on the laser spot size at the cathode of the 7 MeV laser gun. Further simulations showed that a larger beam size reduces the efficiency of the compressor. This problem is cured by focusing elements with a focusing strength depending on the space charge after the gun and integrated into the various compressors layouts under study (four magnets, two magnets and quadrupoles, etc.). The results of these calculations are presented in this paper.

TUPPP027

Subpicosecond Laser Slicing X-Ray Source for Time-resolved Research at TPS

wiggler, emittance, photon, lattice

1671

W.K. Lau, M.C. Chou, C.-S. Hwang, A.P. Lee, Y.-C. Liu, G.-H. Luo
NSRRC, Hsinchu, Taiwan
N.Y. Huang
NTHU, Hsinchu, Taiwan

The 3 GeV Taiwan Photon Source (TPS) under construction at NSRRC should be ready for user run in 2014. X-ray users in many research areas will then be benefited. However, there has been a growing interest in ultrafast time-resolved research in the island. The feasibility of using ultrafast laser for electron-beam slicing at TPS to produce sub-picosecond x-ray pulses is being investigated recently. The design and layout of a laser slicing scheme with W250 wiggler as the energy modulator in a 7 m medium straight section and EPU48 and IU22 radiators in other straight sections will be presented. It will offer the unique opportunity to gain experience in experimental techniques needed for FEL science.

TUPPP048

Increasing the Spectral Range of the CLIO Infrared FEL User Facility by Reducing Diffraction Losses

undulator, vacuum, FEL, simulation

1709

J.-M. Ortega, G. Perilhous, R. Prazeres
LCP/CLIO, Orsay, Cedex, France
H.B. Abualrob, P. Berteaud, L. Chapuis, M.-E. Couprie, T.K. El Ajjouri, F. Marteau, J. Vétéran
SOLEIL, Gif-sur-Yvette, France
J.P. Berthet, F. Glotin
CLIO/ELISE/LCP, Orsay, France

Funding: CNRS/RTRA
The infrared free-electron laser offers a large tunability since the FEL gain remains high throughout the infrared spectral range, and the reflectivity of metal mirrors remains also close to 1. The main limitation comes from the diffraction of the optical beam due to the finite size of the vacuum chamber of the undulator. At CLIO, we have obtained previously* an FEL tunable from 3 to 150 μm by operating the accelerator between 50 and 14 MeV. However, we found that a phenomenon of “power gaps“ is observed in far-infrared : the laser power falls down to zero at some particular wavelengths, whatever the beam adjustments are. We showed that this effect is related to to the waveguiding effect of the vacuum chamber leading to different losses and power outcoupling at different wavelengths**. To alleviate this effect we have designed a new undulator allowing to use a larger vacuum chamber without reducing the spectral tunability and agility of the FEL. From simulations, a large increase of available power is expected in far-infrared. The new undulator has been installed and its performances and first FEL measurement in far-infrared will be presented
* J.M. Ortega, F. Glotin, R. Prazeres
Infrared Physics and Technology, 49, 133 (2006)
** R. Prazeres, F. Glotin, J.-M. Ortega
Phys. Rev. STAB12, 010701 (2009)

TUPPP050

FEL Performances of the French LUNEX5 Project

FEL, electron, bunching, undulator

1712

C. Evain, S. Bielawski
PhLAM/CERCLA, Villeneuve d'Ascq Cedex, France
C. Benabderrahmane, M.-E. Couprie, C. Evain, M. Labat, A. Loulergue
SOLEIL, Gif-sur-Yvette, France
G. Lambert, A. Lifschitz, V. Malka
LOA, Palaiseau, France

LUNEX5 is a french FEL test facility project based on two types of accelerators: a 400 MeV Conventional Linear Accelerator (CLA) and a Laser WakeField Accelerator (LWFA). The FEL performances will be presented at 20 nm and at 12 nm, wavelengths of interest for the pilot experiments. Results are obtained with GENESIS simulations in time-dependent mode. With the CLA, we compare different seeded schemes as EEHG scheme (Echo Enabled Harmonic Generation) or HGHG scheme (High Gain Harmonic Generation) using HHG source (High Harmonic in Gaz). In parallel, LWFA FEL performances will be presented as a function of the electron bunch characteristics, in particular the bunch length and the energy-spread. The transport of the LWFA output beams into undulators which is found to be a critical issue will be also discussed.

TUPPP052

Status of FLASH

FEL, electron, photon, undulator

1715

K. Honkavaara, B. Faatz, J. Feldhaus, S. Schreiber, R. Treusch, M. Vogt
DESY, Hamburg, Germany

FLASH at DESY (Hamburg, Germany) is a free-electron laser user facility driven by a superconducting 1.25 GeV linac based on TESLA technology. During the 3rd user period from September 2010 to September 2011, totally 3740 hours of FEL radiation has been delivered to FEL experiments at more than 30 different wavelengths between 4.7 nm and 45 nm. In addition, beam time has been dedicated to general accelerator physics studies and developments related to the future projects like the European XFEL and the International Linear Collider. After a 3.5 months shutdown in autumn 2011 due to civil construction for a second undulator beamline - FLASH2 - and a following commissioning and study period, 2012 is mainly dedicated to FEL user experiments. This paper summarizes the operation status of the FLASH facility and gives also a short review of the accelerator studies carried out in 2011 and early 2012. The mid-term plans including FLASH2 are presented as well.

TUPPP053

Investigations on the Optimum Accelerator Parameters for the Ultra-Short Bunch Operation of the Free-Electron Laser in Hamburg (FLASH)

emittance, electron, simulation, space-charge

1718

M. Rehders, J. Rönsch-Schulenburg, J. Roßbach
Uni HH, Hamburg, Germany
T. Limberg, H. Schlarb, S. Schreiber
DESY, Hamburg, Germany

Funding: The project is supported by the Federal Ministry of Education and Research of Germany (BMBF) under contract No. 05K10GU2 and FSP301.
In order to produce the shortest possible radiation pulses using Free Electron Lasers like FLASH, various possibilities have been proposed during the last decade. Probably the most robust method is the generation of electron bunches that in the most extreme case are as short as a single longitudinal optical mode of the SASE (Self-Amplified Spontaneous Emission) radiation. For FLASH this means that the bunch length has to be a few fs only. As a consequence, very low bunch charges (in the order of 20 pC) have to be used. To achieve these extremely short bunch lengths, a new photo-injector laser has been installed, which allows for the generation of shorter electron bunches right at the cathode. Simulations of the electron bunches and their six-dimensional phase-space distribution have been performed to investigate the optimum accelerator parameters during injection and to determine how to realize them. First results are discussed in this contribution.

TUPPP056

Study of the Energy Chirp Effects on Seeded FEL Schemes at SDUV-FEL

FEL, electron, radiation, undulator

1724

C. Feng, D. Wang, Z.T. Zhao
SINAP, Shanghai, People's Republic of China

Seeded free-electron laser (FEL) schemes hold great promise for generation of high brilliant radiation with a narrow bandwidth. Analysis with the idealized electron beam with constant current and energy indicate that both the high-gain harmonic generation (HGHG) and the echo-enabled harmonic generation (EEHG) can produce Fourier-transform limited radiation pulses. However, residual energy variations due to nonlinearity of the accelerator or energy modulations due to microbunching instability will be unavoidable and may broaden the bandwidth of the seeded FEL. In this paper, we study the energy chirp effects on both the HGHG and EEHG schemes. Analytic and simulation calculations are presented and compared with the experimental data. Results show that the coherence properties of the EEHG FEL may not be degraded by the energy chirp when properly choosing the parameters of the dispersion sections.

TUPPP057

Design of a Wavelength Continuously Tunable Ultraviolet Coherent Light Source

FEL, radiation, simulation, undulator

1727

T. Zhang, D. Wang, Z.T. Zhao
SINAP, Shanghai, People's Republic of China
X.M. Yang
DICP, Dalian, People's Republic of China

Funding: Work supported by National Natural Science Foundation of China (Grant No. 11075199)
Dalian Coherent Light Source (DCL) is a proposed FEL-based novel light source user facility, will be located in Dalian city, China. DCL will mainly servers on the field of molecular reaction dynamics, ultra-fast physical chemistry experiments, etc. Running on the High-Gain-Harmonic-Generation (HGHG) FEL mode, DCL is expected to cover the FEL wavelength from 50 nm to 150 nm, with the help of continuously tuning Optical Parametric Amplification (OPA) seed laser system, which wavelength can be varied between 240 nm and 360 nm. Numerical simulation shows that the FEL pulse energy of DCL can surpass 100 μJ, at the whole full range wavelength with the undulator tapering technology, and the photon number can be up to 10¹³ per pulse, which is sufficient for user experiments.

TUPPP060

Injector Design for PAL-XFEL Project

gun, emittance, solenoid, cathode

1732

J.H. Han, M.S. Chae, J.H. Hong, I. Hwang, H.-S. Kang, I.S. Ko, S.J. Park
PAL, Pohang, Kyungbuk, Republic of Korea

Funding: The Ministry of Education, Science and Technology of the Korean Government
The PAL-XFEL project has the baseline specification of FEL radiation down to 0.1 nm with a 10 GeV S-band normal conducting linac. To fulfill the requirement of the beam parameter, the S-band photoinjector was designed. Numerical optimizations for nominal and low charge operations are presented.

TUPPP064

Microbunching Instability Studies in SwissFEL

simulation, booster, FEL, linac

1744

S. Bettoni, B. Beutner
Paul Scherrer Institut, Villigen, Switzerland
V.A. Goryashko
NASU/IRE, Kharkov, Ukraine

Shot noise or an initial intensity modulation in the beam pulse may have a strong effect in the FEL linacs and also severely degrade the machine performances in terms of FEL performances. In this paper we present the simulations done to study this effect in SwissFEL, the future free electron laser under design at Paul Scherrer Institute. In particular we calculated the gain of the microbunching instability in the low and high energy part and we performed start-to-end simulations using as initial distribution something as close as possible to the laser profile measured at the SwissFEL injector test facility. We finally present the preliminary calculations to estimate the effect of the laser heater to mitigate this effect.

TUPPP065

Progress Report on the SwissFEL Injector Test Facility

emittance, quadrupole, optics, dipole

1747

T. Schietinger, M. Aiba, S. Bettoni, B. Beutner, M. Csatari, K. Doshekenov, Y.-C. Du, M.W. Guetg, C.P. Hauri, R. Ischebeck, F. Le Pimpec, N. Milas, G.L. Orlandi, M. Pedrozzi, P. Peier, E. Prat, S. Reiche, B. Smit, A. Trisorio, C. Vicario
Paul Scherrer Institut, Villigen, Switzerland

The SwissFEL injector test facility at the Paul Scherrer Institute is the principal test bed and demonstration plant for the SwissFEL project, which aims at realizing a hard-X-ray Free Electron Laser by 2017. The RF photoinjector facility has been in operation since 2010 and has recently reached its design energy of 250 MeV. A newly installed movable magnetic chicane allows longitudinal bunch compression studies. We report on the first experience with the bunch compressor and present the latest results of projected and slice emittance measurements.

Poster TUPPP065 [1.801 MB]

TUPPP066

CLARA - A Proposed New FEL Test Facility for the UK

FEL, electron, undulator, diagnostics

1750

J.A. Clarke, D. Angal-Kalinin, D.J. Dunning, S.P. Jamison, J.K. Jones, J.W. McKenzie, B.L. Militsyn, N. Thompson, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
R. Bartolini
JAI, Oxford, United Kingdom
I.P.S. Martin
Diamond, Oxfordshire, United Kingdom

A new single pass national FEL test facility, CLARA, is proposed to be constructed at Daresbury Laboratory in the UK. The aim of CLARA is to develop a normal conducting test accelerator able to generate longitudinally and transversely bright electron bunches and to use these bunches in the experimental production of stable, synchronized, ultra short photon pulses of coherent light from a single pass FEL with techniques directly applicable to the future generation of light source facilities. In addition the facility will be an ideal test bed for demonstrating innovative technologies such as high repetition rate normal conducting RF linacs and advanced undulator designs. This paper will describe the design of CLARA, pointing out the flexible features that will be incorporated to allow multiple novel FEL schemes to be proven.

TUPPP070

Next Generation Light Source R&D and Design Studies at LBNL

FEL, linac, electron, gun

1762

J.N. Corlett, B. Austin, K.M. Baptiste, D.L. Bowring, J.M. Byrd, S. De Santis, P. Denes, R.J. Donahue, L.R. Doolittle, P. Emma, D. Filippetto, G. Huang, T. Koettig, S. Kwiatkowski, D. Li, T.P. Lou, H. Nishimura, H.A. Padmore, C. F. Papadopoulos, G.C. Pappas, G. Penn, M. Placidi, S. Prestemon, D. Prosnitz, J. Qiang, A. Ratti, M.W. Reinsch, D. Robin, F. Sannibale, D. Schlueter, R.W. Schoenlein, J.W. Staples, C. Steier, C. Sun, T. Vecchione, M. Venturini, W. Wan, R.P. Wells, R.B. Wilcox, J.S. Wurtele
LBNL, Berkeley, California, USA

Funding: Work supported by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
LBNL is developing design concepts for a multi-beamline soft x-ray FEL array powered by a superconducting linear accelerator, operating with a high bunch repetition rate of approximately one MHz. The cw superconducting linear accelerator is supplied by an injector based on a high-brightness, high-repetition-rate photocathode electron gun. Electron bunches are distributed from the linac to the array of independently configurable FEL beamlines with nominal bunch rates up to 100 kHz in each FEL, and with even pulse spacing. Individual FELs may be configured for different modes of operation, and each may produce high peak and average brightness x-rays with a flexible pulse format, and with pulse durations ranging from sub-femtoseconds to hundreds of femtoseconds. In this paper we describe conceptual design studies and optimizations. We describe recent developments in the design and performance parameters, and progress in R&D activities.

TUPPP074

Beam Dynamics Studies of a High-repetition Rate Linac Driver for a 4th-generation Light Source

FEL, emittance, simulation, linac

1771

M. Venturini, J.N. Corlett, P. Emma, C. F. Papadopoulos, G. Penn, M. Placidi, J. Qiang, M.W. Reinsch, F. Sannibale, C. Steier, R.P. Wells
LBNL, Berkeley, California, USA

We present progress toward the design of a super-conducting linac driver of a high repetition rate FEL-based soft x-ray light source. The machine is intended to accept beams generated by the APEX* photocathode gun, operating in the MHz range, and deliver them to an array of SASE and seeded FEL beamlines. After reviewing the beam-dynamics considerations that are informing specific lattice choices we discuss the expected performance of the proposed machine design and its ability to meet the desired FEL specifications. We consider the merit of possible alternate designs (e.g., a one-stage compressor vs. a two-stage compressor) and the trade-offs between competing demands on the beam attributes (e.g., high peak current vs. acceptable energy spread).
* F. Sannibale et al., this conference.

TUPPP086

A Synchronized FIR/VUV Light Source at Jefferson Lab

FEL, wiggler, electron, coupling

1789

S.V. Benson, D. Douglas, G. Neil, M.D. Shinn, G.P. Williams
JLAB, Newport News, Virginia, USA

Funding: This work was supported by U.S. DOE Contract No. DE-AC05-84-ER40150, the Air Force Office of Scientific Research, DOE Basic Energy Sciences.
We describe a dual FEL configuration on the UV Demo FEL at Jefferson Lab that would allow simultaneous lasing at THz and UV wavelengths. The THz source would be an FEL oscillator with a short wiggler providing diffraction-limited pulses with pulse energy exceeding 50 microJoules. The THz source would use the exhaust beam from a UVFEL. The coherent harmonics in the VUV from the UVFEL are outcoupled through a hole. The THz source uses a shorter resonator with either hole or edge coupling to provide very high power THz pulses. Simulations indicate excellent spectral brightness in the THz region with over 100 W/cm^-1 output.

TUPPP090

Studies of Controlled Laser-induced Microbunching Instability at Source Development Laboratory

electron, linac, radiation, space-charge

1798

S. Seletskiy, B. Podobedov, Y. Shen, X. Yang
BNL, Upton, Long Island, New York, USA

We present the studies of controlled microbunching intentionally induced on the beam by the photocathode laser with modulated longitudinal profile. Varying the depth and frequency of longitudinal modulation of the laser pulse allowed us to observe the development of microbunching instability at BNL Source Development Laboratory (SDL) in the controlled environment. That allowed us to benchmark the model of the microbunching gain for the first time. In addition to that, we demonstrated for the first time a constructive work of a so-called longitudinal space charge amplifier, which in case under consideration can be utilized for enhancement of linac-based sources of THz radiation.

TUPPP093

General Results on the Nature of FEL Amplification

electron, FEL, free-electron-laser, wiggler

1804

S.D. Webb
Tech-X, Boulder, Colorado, USA
V. Litvinenko, G. Wang
BNL, Upton, Long Island, New York, USA

Free-electron lasers are increasingly important tools for the material and biological sciences, and although numerical and analytical theory is extensive, a fundamental question about the nature of the FEL growing modes has remained unanswered. In this proceeding, we present results of a topological nature concerning the number of amplifying solutions to the 1-dimensional FEL equations as related to the energy distribution of the electron bunches.

TUPPR012

Polarized Positron Source with a Compton Multiple Interaction Point Line

positron, electron, simulation, linac

1834

I. Chaikovska, O. Dadoun, P. Lepercq, A. Variola
LAL, Orsay, France
R. Chehab
IN2P3 IPNL, Villeurbanne, France

Positron sources are critical components of the future lepton colliders projects. This is essentially due to the high luminosity required, orders of magnitude higher than existing ones. In addition, polarization of the positron beam rather expands the physics research potential of the machine by increasing the precision of the measurements and enhancing certain types of interactions. In this framework, the Compton sources for polarized positron production are taken into account where the high energy gamma rays are produced by the Compton scattering and subsequently converted in the polarized electron-positron pairs in a target. The Compton multiple IP line is proposed as one of the solutions to increase the number of captured positrons. This allows a significant increase in the emitted gamma ray flux impinging on the target. The gamma ray production with the Compton multiple IPs line is simulated and used for polarized positron generation. Later, a capture section based on an adiabatic matching device followed by a pre-injector linac is simulated to capture and accelerate the positron beam. The results obtained are presented and discussed.

WEXB01

Recent Advances and New Techniques in Visualization of Ultra-short Relativistic Electron Bunches

radiation, electron, FEL, RF-structure

2091

D. Xiang
SLAC, Menlo Park, California, USA

Funding: Work supported by U.S. DOE under Contract No. DE-AC02-76SF00515.
This talk will address advances in the measurement of ultra-short relativistic bunches at femtosecond frontier in high-energy x-ray free-electron lasers (FELs). In general, this presentation will discuss several recently proposed novel techniques (i.e. mapping z exactly to delta * and x **, optical oscilloscope ***, etc.) that are capable of breaking the femtosecond time barrier in measurements of ultrashort bunches. In particular, this presentation will report on the all-optical, time-resolved method to probe beam longitudinal phase space with femtosecond time scale and 10^-5 energy scale resolution ****. The simultaneous measurement of temporal profile and beam slice energy spread after the FEL interaction is also shown to reveal the time-dependent x-ray radiation profile *****.
* Z. Huang et al., PRSTAB 13, 092801.
** D. Xiang, Y. Ding, PRSTAB 13, 094001.
*** G. Andonian et al., PRSTAB 14, 072802.
**** D. Xiang et al., PRSTAB 14, 112801.
***** Y. Ding et al., FEL11.

Slides WEXB01 [6.873 MB]

WEYB01

The SPring-8 Angstrom Compact Free Electron Laser (SACLA)

electron, emittance, undulator, FEL

2106

H. Tanaka
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan

Commissioning of the world's first compact X-ray FEL facility named SPring-8 Angstrom Compact free electron LAser (SACLA) began in the Spring of 2011 and soon demonstrated lasing at a wavelength of 0.12nm. In the autumn of 2011 laser intensity reached sub mJ/pulse in the wavelengths ranging from 0.1 to 0.3 nm. The laser power saturation was also achieved at around or longer than 0.1 nm. The official user operation will start from March 2012. This presentation will cover innovative design aspects of the SACLA construction project, events leading to key milestones in the commissioning process, a review of the present status and perspectives on future upgrades.

Slides WEYB01 [13.170 MB]

WEOBB01

Measurement of the Local Energy Spread of Electron Beam at SDUV-FEL

electron, FEL, bunching, radiation

2143

C. Feng, J.H. Chen, H.X. Deng, T. Lan, B. Liu, D. Wang, X. Wang, M. Zhang, T. Zhang, Z.T. Zhao
SINAP, Shanghai, People's Republic of China

The slice energy spread of electron beam is a very important parameter for high gain free electron lasers (FELs) especially the seeded FELs. Because of its extremely small value, highly accurate measurement of the slice energy spread is rather challenging. In this paper, we propose a novel method to accurately measure the slice energy spread based on the coherent harmonic generation (CHG) scheme. This method has been demonstrated on the Shanghai deep ultraviolent FEL (SDUV-FEL), and the results show that the slice energy spread is about only 1.2keV at the exit of the 136MeV linac when the bunch compressor is off, and this value change to about 2.6keV when the bunch compressor is on.
* Chao Feng, et al, Phys. Rev. ST Accel. Beams 14, 090701 (2011)

Slides WEOBB01 [3.309 MB]

WEOBB02

Refraction Contrast Imaging via Laser-Compton X-Ray Using Optical Storage Cavity

electron, cavity, photon, linac

2146

K. Sakaue, T. Aoki, M. Washio
RISE, Tokyo, Japan
M.K. Fukuda, Y. Honda, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan

We have been developing a pulsed-laser storage technique in a super-cavity for a compact x-ray sources. The pulsed-laser super-cavity enables to make high peak power and small waist laser at the collision point with the electron beam. Recently, using 357 MHz mode-locked Nd:VAN laser pulses which stacked in a super-cavity scattered off a multi-bunch electron beam, we obtained a multi-pulse x-rays through the laser-Compton scattering. Then, we performed a X-ray imaging via laser-Compton X-ray. The images have edge enhancement by refraction contrast because the X-ray source spot size was small enough. This is one of the evidences that laser-Compton X-ray is high quality. Our laser-Compton experimental setup, the results of X-ray imaging and future prospective will be presented at the conference.

Slides WEOBB02 [4.393 MB]

WEIC06

Accelerator R&D: Research for Science - Science for Society

acceleration, hadron, proton, emittance

2161

N.R. Holtkamp
SLAC, Menlo Park, California, USA
S. Biedron, S.V. Milton
CSU, Fort Collins, Colorado, USA
L. Boeh, J.E. Clayton, G. Zdasiuk
VMS GTC, Palo Alto, California, USA
S.A. Gourlay, M.S. Zisman
LBNL, Berkeley, California, USA
R.W. Hamm
R&M Technical Enterprises, Pleasanton, California, USA
S. Henderson
Fermilab, Batavia, USA
G.H. Hoffstaetter
CLASSE, Ithaca, New York, USA
L. Merminga
TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
S. Ozaki
BNL, Upton, Long Island, New York, USA
F.C. Pilat
JLAB, Newport News, Virginia, USA
M. White
ANL, Argonne, USA

In September 2011 the US Senate Appropriations Committee requested a ten-year strategic plan from the Department of Energy (DOE) that would describe how accelerator R&D today could advance applications directly relevant to society. Based on the 2009 workshop "Accelerators for America’s Future" an assessment was made on how accelerator technology developed by the nation’s laboratories and universities could directly translate into a competitive strength for industrial partners and a variety of government agencies in the research, defense and national security sectors. The Office of High Energy Physics, traditionally the steward for advanced accelerator R&D within DOE, commissioned a task force under its auspices to generate and compile ideas on how best to implement strategies that would help fulfill the needs of industry and other agencies, while maintaining focus on its core mission of fundamental science investigation.

Slides WEIC06 [3.678 MB]

WEEPPB001

Progress Toward a High-Transformer-Ratio Dielectric Wakefield Experiment at FLASH

electron, wakefield, acceleration, simulation

2166

F. Lemery, D. Mihalcea, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
J. Osterhoff
MPQ, Garching, Munich, Germany
C.A.J. Palmer
DESY, Hamburg, Germany
P. Stoltz
Tech-X, Boulder, Colorado, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357
Dielectric wakefield accelerators offer many advantages over conventional RF accelerators such as higher acceleration gradients and cost effectiveness. In this paper we describe our experimental plans to demonstrate enhanced transformer ratios with drive and witness bunches. The experiment, will be performed at the Free-electron LASer in Hamburg (FLASH) and utilizes unique pulse shaping capabilities using the dual-frequency superconducting linac to produce high transformer ratios (>2). The beam-driven acceleration mechanism will be based on a cylindrical-symmetric dielectric-lined waveguide (DLW). The experimental setup is described, and start-to-end numerical simulations of the experiment will be presented.

WEEPPB002

Plasma Acceleration Experiment at SPARC_LAB with External Injection

plasma, electron, acceleration, injection

2169

L. Serafini, A. Bacci
Istituto Nazionale di Fisica Nucleare, Milano, Italy
M. Bellaveglia, M. Castellano, E. Chiadroni, G. Di Pirro, M. Ferrario, A. Gallo, G. Gatti, A.R. Rossi, C. Vaccarezza
INFN/LNF, Frascati (Roma), Italy
A. Cianchi
Università di Roma II Tor Vergata, Roma, Italy
C. Maroli, V. Petrillo
Universita' degli Studi di Milano, Milano, Italy
A. Mostacci
URLS, Rome, Italy
P. Tomassini
Università degli Studi di Milano, Milano, Italy

At the SPARC-LAB facility of INFN-LNF we are installing two transport lines for ultra-short electron bunches and an ultra-intense laser pulses, generated by the SPARC photo-injector and by the FLAME laser in a synchronized fashion at the tens of fs level, to co-propagate inside a hydrogen filled glass capillary, in order to perform acceleration of the electron bunch by a plasma wave driven by the laser pulse. The main aim of this experiment is to demonstrate that a high brightness electron beam can be accelerated by a plasma wave without any significant degradation of its quality. A 10 pC electron bunch, 10 fs long is produced by SPARC and transported to injection into the capillary, which is 100 micron wide, at a gas density around 5*10¹⁷ ne/cm³ . The laser pulse, 25 fs long, focused down to 30 microns into the capillary is injected ahead of the bunch, drives a weakly non-linear plasma wave with wavelength of about 120 microns. A proper phasing of the two pulses allows acceleration of electrons from the injection energy of 150 MeV up to about 1 GeV for a 10 cm long capillary. Installation of the beam lines is foreseen by the end of 2012 and first tests starting in mid 2013.

WEEPPB003

Modeling of 10 GeV-1 TeV Laser-Plasma Accelerators Using Lorentz Boosted Simulations

plasma, acceleration, simulation, controls

2172

J.-L. Vay, E. Esarey, C.G.R. Geddes, W. Leemans, C.B. Schroeder
LBNL, Berkeley, California, USA
E. Cormier-Michel
Tech-X, Boulder, Colorado, USA
D.P. Grote
LLNL, Livermore, California, USA

Funding: Supported by US-DOE Contracts DE-AC02-05CH11231 and DE-AC52-07NA27344, US-LHC program LARP, and US-DOE SciDAC program ComPASS.
Modeling of laser-plasma wakefield accelerators in an optimal frame of reference [J.-L. Vay, Phys. Rev. Lett. 98 130405 (2007)] allows direct and efficient full-scale modeling of deeply depleted and beam loaded laser-plasma stages of 10 GeV-1 TeV (parameters not computationally accessible otherwise). This verifies the scaling of plasma accelerators to very high energies and accurately models the laser evolution and the accelerated electron beam transverse dynamics and energy spread. Over 4, 5 and 6 orders of magnitude speedup is achieved for the modeling of 10 GeV, 100 GeV and 1 TeV class stages, respectively. Agreement at the percentage level is demonstrated between simulations using different frames of reference for a 0.1 GeV class stage. Obtaining these speedups and levels of accuracy was permitted by solutions for handling data input (in particular particle and laser beams injection) and output in a relativistically boosted frame of reference, as well as mitigation of a high-frequency instability that otherwise limits effectiveness.
Used resources of NERSC, supported by US-DOE Contract DE-AC02-05CH11231.

WEEPPB004

Status of the APEX Project at LBNL

gun, cathode, cavity, electron

2173

F. Sannibale, B.J. Bailey, K.M. Baptiste, J.M. Byrd, C.W. Cork, J.N. Corlett, S. De Santis, L.R. Doolittle, J.A. Doyle, P. Emma, J. Feng, D. Filippetto, G. Huang, H. Huang, T.D. Kramasz, S. Kwiatkowski, W.E. Norum, H.A. Padmore, C. F. Papadopoulos, G.C. Pappas, G.J. Portmann, J. Qiang, D.G. Quintas, J.W. Staples, T. Vecchione, M. Venturini, M. Vinco, W. Wan, R.P. Wells, M.S. Zolotorev, F.A. Zucca
LBNL, Berkeley, California, USA
M. J. Messerly, M.A. Prantil
LLNL, Livermore, California, USA
C.M. Pogue
NPS, Monterey, California, USA

Funding: This work was supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231.
The Advanced Photo-injector Experiment (APEX) at the Lawrence Berkeley National Laboratory is focused on the development of a high-brightness high-repetition rate (MHz-class) electron injector for X-ray FEL applications. The injector is based on a new concept gun, utilizing a normal conducting 186 MHz RF cavity operating in cw mode in conjunction with high quantum efficiency photocathodes capable of delivering the required repetition rates with available laser technology. The APEX activities are staged in 3 main phases. In Phases 0 and I, the gun will be tested at its nominal energy of 750 keV and several different photocathodes are tested at full repetition rate. In Phase II, a pulsed linac will be added for accelerating the beam at several tens of MeV to reduce space charge effects and measure the high-brightness performance of the gun when integrated in an injector scheme. At Phase II energies, the radiation shielding configuration of APEX limits the repetition rate to a maximum of several Hz. Phase 0 is under commissioning, Phase I under installation, and initial activities for Phase II are underway. This paper presents an update on the status of these activities.

WEEPPB006

LCLS Femto-second Timing and Synchronization System Update

controls, LLRF, undulator, EPICS

2176

G. Huang, J.M. Byrd, R.B. Wilcox
LBNL, Berkeley, California, USA
A.R. Fry, B.L. Hill
SLAC, Menlo Park, California, USA

Femto second timing and synchronization system has been installed on LCLS operation for 2 years. The requirement of more receiver at different location of the experimental hall urge us to develop a new version of receiver chassis and sync-head. Two sets of the new receiver chassis has been installed to the SXR and CXI end station. To help end user the diagnose the system, a intermediate GUI is developed to show some diagnostic information.

WEPPC013

Progress of High Gradient Performance in STF 9-cell Cavities at KEK

cavity, accelerating-gradient, status, HOM

2233

Y. Yamamoto, H. Hayano, E. Kako, S. Noguchi, T. Shishido, K. Watanabe
KEK, Ibaraki, Japan

Vertical tests for ILC have been carried out since 2008 at KEK-STF. Measured cavities are from MHI#5 to MHI#22 (not yet for MHI#18-#22 at the end of November 2011), and MHI#12, #13 and #17 reached the ILC specification of 0.8x10¹⁰ at 35MV/m. The MHI cavity was added into the “qualified vendor” for the cavity yield. These three cavities (#12, #13 and #17) had no defect on every EBW seam of equator, iris and beampipe. On the other hand, the other cavities had a few or several defects on EBW seam. Especially, defect on the EBW seam of the equator is the worst case, and cavity performance is limited “certainly”. MHI#10, #15 and #16 cavities were limited by this kind of defect. As for iris region, MHI#14 had large defect at the iris between cell #8 and #9, and the performance was limited by the heavy field emission with “explosive event”. However, after the locally mechanical grind for this defect, the cavity performance was drastically improved with no field emission at 37MV/m. In this paper, the recent progress of the cavity performance at KEK-STF will be reported with the “detailed” defect analysis.

WEPPC034

LA³NET - An International Network on Laser Applications at Accelerators

ion, acceleration, diagnostics, electron

2281

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

Funding: This project is funded by the European Union under contract PITN-GA-2011-289191.
Lasers have become increasingly important for the successful operation and continuous optimization of particle accelerators: Laser-based particle sources are well suited for delivering the highest quality ion and electron beams, laser acceleration has demonstrated unprecedented accelerating gradients and might be an alternative for conventional particle accelerators in the future, and without laser-based beam diagnostics it would not be possible to unravel the characteristics of many complex particle beams. The LA³NET project will bring together research centers, universities, and industry partners to jointly train 17 early stage researchers. In addition, the consortium will also organize a number of international training events, such as schools, topical workshops and conferences. This contribution gives examples from the network's broad research program and summarizes planned training events.

WEPPD048

Laser Synchronization at REGAE using Phase Detection at an Intermediate Frequency

electron, controls, LLRF, feedback

2624

M. Felber, M. Hoffmann, U. Mavrič, H. Schlarb, S. Schulz
DESY, Hamburg, Germany
W. Jałmużna
TUL-DMCS, Łódź, Poland

A new linear accelerator is being set up for electron diffraction experiments at DESY. This machine, called REGAE (Relativistic Electron Gun for Atomic Exploration) is composed of a photo-cathode gun and a buncher cavity. It uses a single laser system for both, the generation of the electron bunches and for pump-probe experiments. The required timing jitter between the electron bunches and the laser pulses at the experiment is in the order of 10 fs rms. The conventional method for laser synchronization using RF technique to measure phase-jitter in the baseband is susceptible to distortions caused by ground-loops and electro-magnetic interference. At REGAE a new scheme for an RF-based laser synchronization is deployed. It uses a down-converter which mixes a higher harmonic of the laser repetition rate down to an intermediate frequency (IF). The IF is digitized and its phase calculated. This information is used for the feedback controller keeping the laser and the RF synchronized.

WEPPD049

Characterization of the Engineered Photodiode-based Fiber Link Stabilization Scheme for Optical Synchronization Systems

LLRF, FEL, optics, controls

2627

T. Lamb, M.K. Bock, M. Felber, F. Ludwig, H. Schlarb, S. Schulz
DESY, Hamburg, Germany
S. Jabłoński
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland

Pulsed optical synchronization systems are used in modern FELs like FLASH and will be used in the upcoming European XFEL. Their purpose is to distribute synchronization signals with femtosecond stability throughout the machine. Optical fibers are used to transport the pulses carrying the timing information to their end-stations. These fibers have to be continuously delay stabilized in order to achieve the desired precision. In this paper, a photodiode-based detector to measure the drifts of the fiber delay and allows their active correction is presented. Promising results from a first prototype setup of a photodiode-stabilized optical fiber link were the starting point for an engineering of this concept. An enclosure with free-space optics, fiber optics and integrated electronics for the detector, operating at 9.75 GHz, was designed. This unit includes all required parts to stabilize four fiber links. It allows to investigate the temperature sensitivity of the detector. Furthermore, results from drift measurements carried out with a two channel engineered detector are presented in this paper.

WEPPD052

Compression and Synchronization of MeV Scale Subpicosecond Electron Beams in a THz IFEL Interaction

undulator, electron, simulation, space-charge

2636

J.T. Moody, R.K. Li, P. Musumeci, C.M. Scoby, H.L. To
UCLA, Los Angeles, California, USA

Recent development of MW peak power THz sources from efficient optical rectification of broadband IR pulses by pulse front tilting has made available laser locked single cycle THz pulses suitable for compression and laser-synchronization of photoinjector generated subpicosecond electron beams. Three dimensional simulations have shown that a waveguided 8 pulse THz train can be used to interact with a sub picoseconds electron beam in an undulator to achieve compression and laser synchronization. We present a THz pulse train source currently under development at UCLA PBPL as well as detailed 3 dimensional simulations including the effect of the interaction on transverse beam quality.
DOE-BES No. DE-FG02-92ER40693 and DOE-BES No. DE-FG02-07ER46272

WEPPD053

The LLNL/UCLA High Gradient Inverse Free Electron Laser Accelerator

electron, undulator, acceleration, simulation

2639

J.T. Moody, P. Musumeci
UCLA, Los Angeles, California, USA
G.G. Anderson, S.G. Anderson, M. Betts, S.E. Fisher, D.J. Gibson, A.M. Tremaine, S.S.Q. Wu
LLNL, Livermore, California, USA

Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
We describe the Inverse Free Electron Accelerator currently under construction at Lawrence Livermore National Lab. Upon completion of this accelerator, high brightness electrons generated in the photoinjector blowout regime and accelerated to 50 MeV by S-band accelerating sections will interact with > 4 TW peak power Ti:Sapphire laser in a highly tapered 50 cm undulator and experience an acceleration gradient of >200 MeV/m. We present the final design of the accelerator as well as the results of start to end simulations investigating preservation of beam quality and tolerances involved with this accelerator.

WEPPD054

Development of Pulsed Laser Systems and Cathode-performance Studies for the S-DALINAC Polarized Injector

cathode, electron, cavity, vacuum

2642

M. Espig, C. Eckardt, J. Enders, Y. Fritzsche, N. Kurichiyanil, J. Lindemann, M. Wagner
TU Darmstadt, Darmstadt, Germany

A source of polarized electrons has recently been implemented at the superconducting Darmstadt electron linear accelerator S-DALINAC. We give an overview of the recent performance of the system. Photo-emission from a superlattice-GaAs photo-cathode is obtained from using either a DC diode laser or a short-pulse Ti:Sapphire laser system. For a robust pulsed quasi-cw operation, it is investigated whether a VECSEL system (Vertical-Cavity Surface-Emitting Laser) can be realized with a wavelength of 780 nm and a repetition rate of 3 GHz with pulse widths of a few picoseconds only. To enhance the availability and performance of the polarized source with respect to quantum efficiency, a separate atomic-hydrogen cleaning system for the cathodes is planned which will allow cathode treatment to be tested and optimized. Supported by DFG within CRC/SFB 634 and by the state of Hesse in the LOEWE-Center HIC for FAIR.

WEPPD055

Gamma-rays Generation with 3D 4-mirror Cavity for ILC Polarized Positron Source

cavity, photon, electron, scattering

2645

T. Akagi, S. Miyoshi
Hiroshima University, Graduate School of Advanced Sciences of Matter, Higashi-Hiroshima, Japan
S. Araki, Y. Funahashi, Y. Honda, T. Okugi, T. Omori, H. Shimizu, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan
H. Kataoka, T. Kon
Seikei University, Japan
M. Kuriki, T. Takahashi
Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan
K. Sakaue, M. Washio
RISE, Tokyo, Japan
R. Tanaka, H. Yoshitama
Hiroshima University, Higashi-Hiroshima, Japan

We are conducting gamma-rays generation experiment by the laser-Compton scattering using a Fabry-Perot cavity. We developed a 3D 4-mirror cavity, and it is installed at the KEK-ATF. By using a 3D 4-mirror cavity, small laser spot can be achieved with stable resonant condition. In addition, we aim 1900 times enhancement of input laser power by a 4-mirror cavity to increase the number of gamma-rays.

WEPPD056

Ytterbium Fiber Laser System of DAW RF Gun for SuperKEKB

emittance, gun, cavity, luminosity

2648

X. Zhou, T. Natsui, Y. Ogawa, M. Yoshida
KEK, Ibaraki, Japan

For obtaining higher luminosity in the SuperKEKB, the photocathode DAW-type RF gun for high-current, low-emittance beams will be employed in the injector linac. The electron beams with a charge of 5 nC and a normalized emittance of 10 micrometer are expected generate in the photocathode RF gun by using the laser source with a center wavelength of 260 nm and a pulse width of 30 ps. Fiber laser especially Ytterbium(Yb) fiber have attracted attention as one of the promising practical alternatives to usual solid-state lasers, offering high energy-extraction efficiency, high repetition rate, high output power, low-cost and so on. Introducing the Ytterbium fiber laser system, we have developed a stable laser amplifier system, which could allow steady beam injection into the SuperKEKB rings. The laser system starts with a large mode-area Yb-doped fiber-based amplifier system, which consists of a passively mode-locked femtosecond Yb-fiber oscillator. To obtain the mJ-class pulse energy, a multi-pass solid-state amplifier is employed. Deep UV pulses for the photocathode are generated by using two frequency-doubling stages. High pulse energy and good stability would be expected.

WEPPD059

Proton Acceleration by a Relativistic Laser Frequency-Chirp Driven Plasma Snowplow

plasma, proton, electron, acceleration

2654

A. A. Sahai, T.C. Katsouleas
Duke ECE, Durham, North Carolina, USA
R. Bingham
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
W.B. Mori, A. Tableman, F.S. Tsung, M. Tzoufras
UCLA, Los Angeles, California, USA

Funding: NSF-PHY-0936278, NSF-PHY-0904039 and NSFPHY-0936266, US DOE DE-FC02-07ER41500 and DE-FG02-92ER40727, DOE Fusion Science Center through a University of Rochester Subcontract No. 415025-G.
We analyze the use of a relativistic laser pulse with a controlled frequency chirp incident on a rising plasma density gradient to drive an acceleration structure for proton and light ion acceleration. The Chirp Induced Transparency Acceleration (ChITA) scheme is described with an analytical model of the velocity of the snowplow at critical density on a pre-formed rising plasma density gradient that is driven by positive chirp in the frequency of a relativistic laser pulse. The velocity of the ChITA-snowplow is shown to depend upon rate of rise of the frequency of the relativistic laser pulse, the normalized magnetic vector potential of the laser pulse and the plasma density gradient scale-length. We observe using 1-D OSIRIS simulations the formation and forward propagation of ChITA-snowplow, being continuously pushed by the chirping laser at a velocity in accordance with the analytical results. The trace protons reflect off of this propagating snowplow structure and accelerate monoenergetically. The control over ChITA-snowplow velocity allows the tuning of accelerated proton energies.

WEPPD060

A Drive Laser for Multi-bunch Photoinjector Operation

electron, brightness, cathode, emittance

2657

D.J. Gibson, C.P.J. Barty, M. J. Messerly, M.A. Prantil
LLNL, Livermore, California, USA
E. Cormier
CELIA, Talence, France

Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344
Numerous electron beam applications would benefit from increased average current without sacrificing beam brightness. Work is underway at LLNL to investigate the performance of X-band photoinjectors that would generate electron bunches at a rate matching the RF drive frequency, i.e. one bunch per RF cycle. A critical part of this effort involves development of photo-cathode drive laser technology. Here we present a new laser architecture that can generate pulse trains at repetition rates up to several GHz. This compact, fiber-based system is driven directly by the accelerator RF and so is inherently synchronized with the accelerating fields, and scales readily over a wide range of drive frequencies (L-band through X-band). The system will be required to produce 0.5 μJ, ~200 fs rise time, spatially and temporally shaped UV pulses designed to optimize the electron beam brightness. Presented is the current status of this system, producing pulses shorter than 2 ps from a cw source.

WEPPD065

Development of a Laser-based Alignment System Utilizing Fresnel Zone Plates at the KEKB Injector Linac

alignment, scattering, linac, focusing

2672

T. Suwada, M. Satoh
KEK, Ibaraki, Japan
K. Minoshima, S. Telada
AIST, Tsukuba, Japan

A new laser-based alignment system is under development in order to precisely align accelerator components along an ideal straight line at the 600-m-long KEKB injector linac. A well-known sequential three-point method with Fresnel zone plates and a CCD camera is revisited in the alignment system. The high-precision alignment system is strongly required in order to stably accelerate high-brightness electron and positron beams with high bunch charges and also to keep the beam stability with higher quality towards the Super B-factory at KEK. A new laser optics has been developed and the laser propagation characteristics has been systematically investigated at a 100-m-long straight section in vacuum. In this report, the experimental developments and investigations are reported along with the design of the new laser-based alignment system.

WEPPD073

Strategy and Validation of Fiducialization for the Pre-alignment of CLIC Components

alignment, controls, linac, target

2693

S. griffet, A. Cherif, J. Kemppinen, H. Mainaud Durand, V. Rude, G. Sterbini
CERN, Geneva, Switzerland

The feasibility of the high energy e⁺ e⁻ linear collider CLIC (Compact Linear Collider) is very dependent on the ability to accurately pre-align its components. There are two 20-km-long Main Linacs which meet in an interaction point (IP). The Main Linacs are composed of thousands of 2 m long modules. One of the challenges is to meet very tight alignment tolerances at the level of CLIC module: for example, the center of a Drive Beam Quad needs to be aligned within 20 μm rms with respect to a straight line. Such accuracies cannot be achieved using usual measurement devices. Thus it is necessary to work in close collaboration with the metrology lab. To test and improve many critical points, including alignment, a CLIC mock-up is being assembled at CERN. This paper describes the application of the strategy of fiducialization for the pre-alignment of CLIC mock-up components. It also deals with the first results obtained by performing measurements using a CMM (Coordinate Measuring Machine) to ensure the fiducialization, using a Laser Tracker to adjust or check components’ positions on a girder and finally using a Measuring Arm to perform dimensional control after assembling steps.

WEPPD077

Generation of Picosecond Electron-bunch Trains with Variable Spacing Using a Multi-pulse Photocathode Laser

quadrupole, electron, wakefield, simulation

2705

P. Piot
Fermilab, Batavia, USA
M.E. Conde, W. Gai, C.-J. Jing, R. Konecny, W. Liu, J.G. Power, Z.M. Yusof
ANL, Argonne, USA
D. Mihalcea, P. Piot, M.M. Rihaoui
Northern Illinois University, DeKalb, Illinois, USA

Funding: Work supported by DOE awards FG-02-08ER41532 and DE-AC02-06CH11357.
We demonstrate the generation of a train of electron bunches with variable spacing at the Argonne Wakefield Accelerator. The photocathode ultraviolet laser pulse consists of a train of four pulses produced via polarization splitting using two alpha-BBO crystals. The photoemitted electron bunches are then manipulated in a horizontally-bending dogleg with variable longitudinal dispersion. A downstream vertically-deflecting cavity is then used to diagnose the temporal profile of the electron beam. The generation of a train composed of four bunches with tunable spacing is demonstrated. Such train of bunch could have application to, e.g., the resonant excitation of wakefield in dielectric-lined waveguides.

WEPPP006

Using Simulations to Understand Particle Dynamics and Resonance in the Micro-accelerator Platform

resonance, electron, coupling, acceleration

2732

J.C. McNeur, G. Travish
UCLA, Los Angeles, USA
H. Hairong
UESTC, Chengdu, Sichuan, People's Republic of China
R.B. Yoder
Manhattanville College, Purchase, New York, USA

Funding: Work funded in part by grant HDTRA1-09-1-0043 from the US Defense Threat Reduction Agency and under a grant from NNSA/NA-221 Office of Nonproliferation and Verification Research and Development.
The Micro-Accelerator Platform (MAP) is a slab-symmetric micron-scale electron accelerator. Electrons gain energy via a standing wave electromagnetic resonance powered by a side coupled Ti:Sapphire laser. In this paper, we will discuss simulations of resonance and particle dynamics in this structure. Three-dimensional simulations showing evidence of stable 1 GeV/m acceleration are detailed along with simulations studying defocusing and wakefield effects in the MAP. Additionally, optimization of the structure and the coupling of laser power into the cavity will be explored.

WEPPP008

Vacuum Laser Acceleration Experiment Perspective at Brookhaven National Lab-Accelerator Test Facility

electron, acceleration, vacuum, simulation

2735

X.P. Ding, D.B. Cline, L.S. Shao
UCLA, Los Angeles, California, USA
M.G. Fedurin, K. Kusche, I. Pogorelsky, V. Yakimenko
BNL, Upton, Long Island, New York, USA
Y.K. Ho, Q. Kong
Fudan University, Shanghai, People's Republic of China
J.J. Xu
Shanghai Institute of Optics and Fine Mechanics, Shanghai, People's Republic of China

Funding: Supported by the DOE under award number DE-FG02-92ER40695 (UCLA)
This paper presents the pre-experiment plan and prediction of the first stage of Vacuum Laser Acceleration (VLA) collaborating by UCLA, Fudan University and ATF-BNL. This first stage experiment is a Proof-of-Principle to support our previously posted novel VLA theory. Simulations show that based on ATF’s current experimental conditions, the electron beam with initial energy of 15MeV can get net energy gain from intense CO2 laser beam. The difference of electron beam energy spread is observable by ATF beam line diagnostics system. Further this energy spread expansion effect increases along with the laser intensity increasing. The proposal has been approved by ATF committee and experiment will be the next project.

WEPPP009

Experimental Progress Towards a Resonant Slab-symmetric Dielectric Laser Accelerator

simulation, electron, acceleration, vacuum

2738

G. Travish, K.S. Hazra, G. Liu, J.C. McNeur, E.B. Sozer, J. Zhou
UCLA, Los Angeles, California, USA
H. Hairong
UESTC, Chengdu, Sichuan, People's Republic of China
R.B. Yoder
Manhattanville College, Purchase, New York, USA

Funding: Work funded in part by grant HDTRA1-09-1-0043 from the US Defense Threat Reduction Agency and under a grant from NNSA/NA-221 Office of Nonproliferation and Verification Research and Development.
TheμAccelerator Platform (MAP), a resonant dielectric structure for laser acceleration of electrons, has been in development for a number of years. It consists of a a vacuum gap between two slab-shaped reflecting boundaries, with a transmissive grating diffractive optic on one boundary that allows laser power to propagate into the gap and enforces an accelerating mode. We report on the progress of bench and beam tests carried out within the last year, and the challenges faced in diagnosing <pC beams from optical-scale structures. We also describe refinements to our fabrication techniques and lessons learned during the development of the fabrication process.

WEPPP014

Modeling of Quasi-phase Matching in an Aperiodic Corrugated Plasma Waveguide for High-efficiency Direct Laser Electron Acceleration

electron, plasma, acceleration, simulation

2750

M.W. Lin
The Pennsylvania State University, University Park, Pennsylvania, USA
I. Jovanovic
Penn State University, University Park, Pennsylvania, USA

Funding: This work is supported by the Defense Threat Reduction Agency through contract HDTRA1-10^-1-0034.
Direct laser acceleration (DLA) of charged particles using the axial electric field of a radially polarized intense laser pulse has the potential to realize a compact accelerator required in security and medical applications. The implementation of guided propagation of laser pulses over long distances and the phase matching between electrons and laser pulses may limit the performance of DLA in reality*. A corrugated plasma waveguide could be applied to extend the laser beam propagation distance and for quasi-phase matching between laser and electron pulses for net acceleration. To accelerate electrons from a low initial energy (for example, ~5 MeV from a photoinjector gun) up to hundreds of MeV, an aperiodic corrugated plasma waveguide with successive increase of on-axis density modulation period is needed**. We conducted particle-in-cell simulations to design the appropriate aperiodic plasma structure for DLA. For each section of the corrugated waveguide, the dependence of density modulation period on the initial electron energy and laser pulse intensity is investigated. The simulation results are guiding the design of proof-of-principle experiments for compact, tabletop DLA.
* P. Serafim, et al., IEEE Trans. Plasma Sci. 28, 1155 (2000).
** J. P. Palastro, et al., Phys. Rev. E. 77, 036405 (2008).

WEPPP016

De-neutralization of Laser Produced Proton Pulse in a Strong Solenoidal Magnetic Field

electron, proton, simulation, focusing

2755

M. Droba, O.K. Kester, O. Meusel, C. Wiesner
IAP, Frankfurt am Main, Germany

Laser generated proton pulses of ten to several ten MeV produced in PHELIX-laser facility at GSI Darmstadt poses some unique characteristics. The first systematic exploration of the interface between proton pulse generation via the TNSA mechanism and conventional accelerator technology is within the scope of the LIGHT (Laser Ion Generation, Handling and Transport) project. One of the main tasks is to study the beam dynamics in intense B-fields, especially in context of early de-neutralization and space charge effects. The 3D numerical simulations with co-moving electrons and up to 10⁷ macroparticles were performed to investigate the de-neutralization process in the focusing magnetic solenoid. Importance of the first focusing element and influence on beam parameters will be addressed. Results of the 3D simulation model will be presented and discussed.

WEPPP017

Recent Results at the SPARC_LAB Facility

electron, plasma, injection, photon

2758

M. Ferrario, D. Alesini, M.P. Anania, M. Bellaveglia, R. Boni, M. Castellano, E. Chiadroni, G. Di Pirro, A. Drago, A. Esposito, A. Gallo, C. Gatti, G. Gatti, A. Ghigo, T. Levato, E. Pace, L. Pellegrino, R. Pompili, A.R. Rossi, B. Spataro, P. Tomassini, C. Vaccarezza, F. Villa
INFN/LNF, Frascati (Roma), Italy
A. Bacci, C. De Martinis, L. Serafini
Istituto Nazionale di Fisica Nucleare, Milano, Italy
A. Cianchi
Università di Roma II Tor Vergata, Roma, Italy
G. Dattoli, E. Di Palma, L. Giannessi, A. Petralia, M. Quattromini, C. Ronsivalle, I.P. Spassovsky, V. Surrenti
ENEA C.R. Frascati, Frascati (Roma), Italy
D. Di Giovenale
INFN-Roma II, Roma, Italy
U. Dosselli
INFN, Roma, Italy
R. Faccini
INFN-Roma, Roma, Italy
R. Fedele
Naples University Federico II, Mathematical, Physical and Natural Sciences Faculty, Napoli, Italy
M. Gambaccini
INFN-Ferrara, Ferrara, Italy
D. Giulietti
UNIPI, Pisa, Italy
L.A. Gizzi, L. Labate
CNR/IPP, Pisa, Italy
P. Londrillo
INFN-Bologna, Bologna, Italy
S. Lupi
Università di Roma I La Sapienza, Roma, Italy
A. Mostacci, L. Palumbo
Rome University La Sapienza, Roma, Italy
G. Passaleva
INFN-FI, Sesto Fiorentino, Italy
V. Petrillo
Universita' degli Studi di Milano, Milano, Italy
J.V. Rau
ISM-CNR, Rome, Italy
G. Turchetti
Bologna University, Bologna, Italy

A new facility named SPARC_LAB (Sources for Plasma Accelerators and Radiation Compton with Lasers and Beams) has been recently launched at the INFN National Labs in Frascati, merging the potentialities of the old projects SPARC and PLASMONX. The SPARC project, a collaboration among INFN, ENEA and CNR, is now completed, hosting a 150 MeV high brightness electron beam injector which feeds a 12 meters long undulator. Observation of FEL radiation in the SASE, Seeded and HHG modes has been performed from 500 nm down to 40 nm wevelength. A second beam line has been also installed to drive a narrow band THz radiation source. In parallel to that, INFN decided to host a 300 TW laser that will be linked to the linac and devoted to explore laser-matter interaction, in particular with regard to laser-plasma acceleration in the self injection and external injection modes, (the PLASMONX experiments). The facility will be also used for particle driven plasma acceleration experiments (the COMB experiment). A Thomson scattering experiment coupling the electron bunch to the high-power laser to generate coherent monochromatic X-ray radiation is also in the commissioning phase.

WEPPP019

Designing of Photonic Crystal Accelerator for Radiation Biology

electron, vacuum, injection, acceleration

2763

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

Funding: This work was performed as part of the Global COE Program (Nuclear Education and Research Initiative, MEXT, Japan.
A photonic crystal accelerator with a combination of a fiber laser is under development in order to apply it to the radiation biology. In order to investigate fundamental biological processes in a cell, a DNA is precisely shot by an electron bunch with an in situ observation of a radiation interaction using a microscope. Required beam diameter, bunch length, and beam energy are nanometer, attosecond, and 100 keV to 1 MeV, respectively. A photonic crystal or dielectric laser accelerator energized by a fiber laser is suitable for producing such a fine beam with a palm top device. A preliminary estimation shows that 200 keV electron bunch is available from a 0.8-mm-long accelerator and a few cm electron gun, which is driven by a few μJ, 5-ps laser pulse. We are developing a fiber laser in order to drive the photonic crystal accelerator. The Yb-fiber oscillator delivers mode-locked pulse train of ≈5 nJ/pulse at the repetition frequency of 62.5 MHz. The output pulse will be increased to several μJ by adopting a fiber amplifier

WEPPP029

Quasi-Monoenergetic Ion Bunch Generating by Two-Stage Laser Acceleration

ion, acceleration, target, light-ion

2787

G. Dudnikova
UMD, College Park, Maryland, USA
D. Gorpinchenko
ICM&MG SB RAS, Novosibirsk, Russia

Experiments carried out in recent years on the laser-plasma interaction show the possibility of ions acceleration to high energy. The energy spectrum of these ions is typically broad. Practical applications require that the beams of accelerated ions be monoenergetic. A scheme is proposed for producing a quasi-monoenergetic ion bunch by irradiating a foil with two subsequent laser pulses–a prepulse followed by a stronger main pulse. We have demonstrated a possible mechanism for generating a quasi-monoenergetic ion bunch from a homogeneous target consisting of atoms of the same species by the two-stage acceleration. Results are presented from 2D and 3D PIC simulation that illustrate the scheme and determine the space–time and energy characteristics of the accelerated ions. Investigation was made by varying such control parameters as the duration and amplitude of the main laser pulse and the prepulse, the time lag between the pulses, and the thickness and density of the foil.

WEPPP030

Experimental Generation of a Double-bunch Electron Beam by Transverse-to-Longitudinal Phase Space Exchange

electron, focusing, cathode, gun

2789

T.J. Maxwell, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
A.S. Johnson, A.H. Lumpkin, J. Ruan, Y.-E. Sun, R.M. Thurman-Keup
Fermilab, Batavia, USA

Funding: Supported by Fermi Research Alliance, LLC under U.S. Dept. of Energy Contract No. DE-AC02-07CH11359, and Northern Illinois Univ. under US Dept. of Defense DURIP program Contract N00014-08-1-10⁶⁴.
In this paper we demonstrate the generation of a tunable, longitudinal double-pulse electron beam. Experimental results on the generation of electron bunch trains with sub-picosecond structure have been previously reported where an initial transverse electron beam modulation was produced by masking the electron beam directly*. Here the initial transverse structure is imparted by masking of the photoinjector drive laser to effectively produce two horizontally offset beams at photoemission in the RF gun. A longitudinal double-pulse modulation is then realized after a transverse-to-longitudinal phase-space exchange beamline. Longitudinal profile tuning is demonstrated by upstream beam focusing in conjunction with downstream monitoring of single-shot electro-optic spectral decoding of coherent transition radiation.
* Y.-E. Sun et al., Tunable Subpicosecond Electron-Bunch-Train Generation Using a Transverse-To-Longitudinal Phase-Space Exchange Technique, Phys. Rev. Lett. 10⁵, 234801 (2010).

WEPPP032

Inverse Free Electron Laser Acceleration Using Ultra-fast Solid State Laser Technology

undulator, simulation, acceleration, electron

2795

S.G. Anderson, G.G. Anderson, S.M. Betts, S.E. Fisher, D.J. Gibson, A.M. Tremaine, S.S.Q. Wu
LLNL, Livermore, California, USA
J.T. Moody, P. Musumeci
UCLA, Los Angeles, California, USA

Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
We present a theoretical and computational study of the application of Ti:Sapphire laser technology to Inverse Free Electron Laser (IFEL) accelerators. Specifically, the regime in which the number of undulator periods is comparable to the number of cycles in the laser pulse is investigated and modifications to the IFEL accelerator equations and laser requirements are given. 1-D and 3-D simulations are used to study the IFEL interaction in this regime. In addition, the effects of non-Gaussian laser pulses, and astigmatic aberrations in the laser focus are analyzed. Finally, the tools developed for this study are applied to the LLNL/UCLA IFEL experiment, and potential future IFEL designs.

WEPPP036

Undulator Commissioning for a High-Energy-Gain Inverse Free Electron Laser Experiment

undulator, electron, simulation, acceleration

2804

J.P. Duris, R.K. Li, P. Musumeci, E.W. Threlkeld
UCLA, Los Angeles, California, USA

Funding: This work was supported by DOE grant DE-FG02-92ER40693 and Defense of Threat Reduction Agency award HDTRA1-10^-1-0073.
We present the construction and measurement details of a strongly tapered helical undulator for the Rubicon Inverse Free Electron Laser (IFEL) experiment. Results of the magnetic field measurements are presented, and these are used to produce simulations of the expected performance of the experiment. Finally, a study of the tolerances on the input parameters of the experiment is presented.

WEPPP040

Progress Report on Development of Novel Ultrafast Mid-IR Laser System

acceleration, FEL, wakefield, background

2810

R. Tikhoplav, A.Y. Murokh
RadiaBeam, Santa Monica, USA
I. Jovanovic
Penn State University, University Park, Pennsylvania, USA

Finding alternate acceleration mechanisms that can provide very high gradients is of particular interest to the accelerator community. Those mechanisms are often based on either dielectric laser acceleration or laser wakefield acceleration techniques, which would greatly benefit from mid-IR ultrafast high peak power laser systems. The approach of this proposed work is to design a novel ultrafast mid-IR laser system based on optical parametric chirped-pulse amplification (OPCPA). OPCPA is a technique ideally suited for production of ultrashort laser pulses at the center wavelength of 2μm-5μm. Some of the key features of OPCPA are the wavelength agility, broad spectral bandwidth and negligible thermal load. This paper reports on the progress of the development of the ultrafast mid-IR laser system.

WEPPP041

Wakefield Breakdown Test of a Diamond-loaded Accelerating Structure at the AWA

wakefield, vacuum, simulation, electron

2813

S.P. Antipov, J.E. Butler, C.-J. Jing, A. Kanareykin, P. Schoessow, S.S. Zuo
Euclid TechLabs, LLC, Solon, Ohio, USA
S. Baryshev, M.E. Conde, D.S. Doran, W. Gai, R. Konecny, J.G. Power, Z.M. Yusof
ANL, Argonne, USA

Funding: DOE SBIR
Diamond has been proposed as a dielectric material for dielectric loaded accelerating (DLA) structures. It has a very low microwave loss tangent, the highest available thermoconductive coefficient and high RF breakdown field. In this paper we report results from a wakefield breakdown test of diamond-loaded rectangular accelerating structure. The high charge beam from the AWA linac (~70 nC, σz = 2.5mm) will be passed through a rectangular diamond - loaded resonator and induce an intense wakefield. A groove is cut on the diamond to enhance the field. Electric fields up to 0.5 GV/m will be present on the diamond surface to attempt to initiate breakdown. A surface analysis of the diamond is be performed before and after the beam test.

WEPPP044

Advances in CVD Diamond for Accelerator Applications

wakefield, plasma, acceleration, electron

2819

A. Kanareykin, S.P. Antipov, J.E. Butler, C.-J. Jing, S.S. Zuo
Euclid TechLabs, LLC, Solon, Ohio, USA

Funding: Work supported by the SBIR program of the US Department of Energy.
Diamond is being evaluated as a dielectric material for dielectric loaded accelerating structures. It has a very low microwave loss tangent, high thermal conductivity, and supports high RF breakdown fields. We report on progress in fabricating chemical vapor deposited (CVD) diamond materials for cylindrical dielectric structures for use in wakefield particle accelerators. Tubes with inner diameters of 3 and 5 mm have been grown from polycrystalline CVD diamond on mandrels using microwave plasma assisted CVD. The material has been laser trimmed to the desired thicknesses and lengths. In addition, structures with smaller inner diameters (ca. 0.3 mm) have been laser machined from blocks of single crystal diamond grown by CVD. Rectangular (planar) dielectric structures have been constructed from plates of polished CVD diamond. Wakefields in these structures have been studied at the Brookhaven ATF.

WEPPP051

Excitation of Plasma Wakefields with Designer Bunch Trains

plasma, wakefield, emittance, cathode

2828

P. Muggli
MPI, Muenchen, Germany
B.A. Allen, Y. Fang
USC, Los Angeles, California, USA
M. Babzien, M.G. Fedurin, K. Kusche, R. Malone, C. Swinson, V. Yakimenko
BNL, Upton, Long Island, New York, USA

Funding: Work supported by US Department of Energy.
Plasma can sustain multi-GV/m longitudinal electric fields that can be used for particle acceleration. In the plasma wakefield accelerator, or PWFA, the wakefields are driven by a single or a train of electron bunches with length comparable to the plasma wavelength. A train of bunches resonantly driving the wakefields can lead to energy gain by trailing particles many times the energy of the incoming drive train particles (large transformer ratio). In proof-of-principle experiments at the Brookhaven National Laboratory Accelerator Test Facility, we demonstrate by varying the plasma density over four orders of magnitude, and therefore the accelerator frequency over two orders of magnitude (~100GHz to a few THz), that trains with ~ps period resonantly drive wakefields in ~10¹⁶/cc density plasmas. We also demonstrate energy gain by a trailing witness electron bunch that follows the drive train with a variable delay. Detailed experimental results will be presented.

WEPPP072

Beam Characterization and Coherent Optical Transition Radiation Studies at the Advanced Photon Source Linac

emittance, linac, diagnostics, radiation

2876

J.C. Dooling, R.R. Lindberg, N. Sereno, C.-X. Wang
ANL, Argonne, USA
A.H. Lumpkin
Fermilab, Batavia, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under contract number DE-AC02-06CH11357.
The Advanced Photon Source facility includes a 450-MeV S-band linac with the option for injection from a photocathode (PC) rf gun. A diode-pumped, twice-frequency doubled Nd:glass regen laser (263 nm) is used with the Cu PC to generate the electron beams. Characterization of these beams and studies of the microbunching instability following beam compression in the four-dipole magnetic chicane are described. A suite of diagnostics is employed including a three-screen emittance section, a FIR coherent transition radiation autocorrelator, electron spectrometers, and an optical diagnostics end station. An energy chirp impressed on the beam is used to compress the 1-2 ps, rms bunch as it passes through the chicane. With compression, bunch lengths of 170-200 fs, rms at 450 pC are measured, and coherent optical transition radiation (COTR) due to the microbunching instability is observed. Mitigation techniques of the COTR in the beam profile diagnostics are demonstrated both spectrally and temporally. At 100 pC without compression normalized transverse emittances of 1.8 and 2.7 microns are observed in the x and y planes, in reasonable agreement with initial ASTRA simulations.

WEPPP081

Fast Beam Tuning for Accelerator Driven Systems

controls, target, linac, proton

2897

S. Bhattacharyya, R.K. Yedavalli
Ohio State University, USA
A. Mukherjee
Fermilab, Batavia, USA

The biggest challenge for Accelerator Driven Systems (ADS) is the stringent availability requirement of >99% compared to ~80% achieved by a typical accelerators. In addition to overall availability, due to thermal stress problems, ADS is also sensitive to the length of each downtime. A significant source of downtime is re-adjustment – “tuning” – of the system to account for drift in component behavior, or substitution of a backup device for one that failed. Tuning at present is done “by hand,” i.e. with human observation, interpretation, and decision, a process which takes hours; whereas ADS requires recovery in minutes. In this research, we apply intelligent controls in a (simulated) proton linac to automate fine-tuning. Beam monitor data is fed into a controller which adjusts magnet currents and RF power to minimize beam loss. We consider fluctuations in ion source characteristics; drift in magnet behavior (mechanical motion, or change in calibration); and failure of an accelerating cavity.

WEPPP087

The Improvement and Test of Laser Positioning System for TPS Magnets Alignment Inspection

quadrupole, alignment, sextupole, insertion

2915

M.L. Chen, J.-R. Chen, H.C. Ho, K.H. Hsu, W.Y. Lai, C.-S. Lin, C.J. Lin, H.C. Lin, H.M. Luo, S.Y. Perng, P.L. Sung, Y.L. Tsai, T.C. Tseng, H.S. Wang, M.H. Wu
NSRRC, Hsinchu, Taiwan

A Laser positioning system, consist of a laser, laser position sensing devices (PSD) module and two granite blocks, is developed for the alignment inspection of TPS (Taiwan Photon Source) quadrupole and sextupole magnets during installation on a girder. The PSD module is adapted on the pole center of magnet and is designed to stand for mechanical center of magnets. For high accuracy, eliminating the influence of magnets manufacturing errors between PSD module is a major work. The PSD is mounted on a precise diameter expansible jig to absorb the manufacturing errors. The real roundness of the expansible jig can keep under 3um when diameter is expanded 80um. The PSD position is adjusted and corrected in advance, and then the PSD module center can be identical to the ideal pole position of magnets on the girder within 15um. The magnet will be aligned and adjusted by laser position on PSD. This paper describes how to eliminate the measuring error caused by magnet manufacturing error and the detail of alignment inspection procedure of magnets during the installation on a girder.

WEPPP088

Auto-alignment System and CalibrationPprocedure in TPS Girder System

alignment, survey, storage-ring, photon

2918

W.Y. Lai, J.-R. Chen, M.L. Chen, H.C. Ho, K.H. Hsu, D.-G. Huang, C.K. Kuan, C.-S. Lin, C.J. Lin, H.M. Luo, S.Y. Perng, P.L. Sung, Y.L. Tsai, T.C. Tseng, H.S. Wang, M.H. Wu
NSRRC, Hsinchu, Taiwan

The TPS (Taiwan photon source) project is under construction and will be finished in the December 2012. Considering the floor’s deformation with time and frequent earthquakes at Taiwan, the survey and alignment procedure should be taken quite often. For dealing with these difficulties and improving accuracy of girder’s position, a highly accurate auto-tuning girders system was designed to accomplish the alignment tasks. There are two cells of TPS girders and varied sensor modulus set up for testing the auto-tuning system. The adjustment of the system converges to less than 6um, and the repeatability of the testing is under 10 um. For improving the accuracy of girders position, that is critical thing to make sure all the calibration of sensors modulus correctly and accurately. The calibration procedure about sensor modular and testing results is described in this paper.

WEPPR076

Positron Options for the Linac-ring LHeC

target, positron, emittance, electron

3108

F. Zimmermann, O.S. Brüning, Y. Papaphilippou, D. Schulte, P. Sievers
CERN, Geneva, Switzerland
H.-H. Braun
Paul Scherrer Institut, Villigen, Switzerland
E.V. Bulyak
NSC/KIPT, Kharkov, Ukraine
M. Klein
The University of Liverpool, Liverpool, United Kingdom
L. Rinolfi
JUAS, Archamps, France
A. Variola, Z.F. Zomer
LAL, Orsay, France
V. Yakimenko
BNL, Upton, Long Island, New York, USA

The full physics program of a future Large Hadron electron Collider (LHeC) requires both pe⁺ and pe- collisions. For a pulsed 140-GeV or an ERL-based 60-GeV Linac-Ring LHeC this implies a challenging rate of, respectively, about 1.8·10¹⁵ or 4.4·10¹⁶ e+/s at the collision point, which is about 300 or 7000 times the past SLC rate. We consider providing this e⁺ rate through a combination of measures: (1) Reducing the required production rate from the e⁺ target through colliding e⁺ (and the LHC protons) several times before deceleration, by reusing the e⁺ over several acceleration/deceleration cycles, and by cooling them, e.g., with a compact tri-ring scheme or a conventional damping ring in the SPS tunnel. (2) Using an advanced target, e.g., W-granules, rotating wheel, sliced-rod converter, or liquid metal jet, for converting gamma rays to e+. (3) Selecting the most powerful of several proposed gamma sources, namely Compton ERL, Compton storage ring, coherent pair production in a strong laser, or high-field undulator radiation from the high-energy lepton beam. We describe the various concepts, present example parameters, estimate the electrical power required, and mention open questions.

THYA02

Ultracompact Accelerator Technology for a Next-generation Gamma-Ray Source

gun, klystron, electron, photon

3190

R.A. Marsh, F. Albert, S.G. Anderson, C.P.J. Barty, D.J. Gibson, F.V. Hartemann, S.S.Q. Wu
LLNL, Livermore, California, USA

Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
This presentation will report on the technology choices and progress manufacturing and testing the injector and accelerator of the 250 MeV ultra-compact Compton Scattering X-ray Source under development at LLNL for homeland security applications.

Slides THYA02 [12.896 MB]

THEPPB001

Design and Fabrication of The ESS-Bilbao RFQ Prototype Models

rfq, vacuum, alignment, simulation

3228

I. Bustinduy, F.J. Bermejo, J. Feuchtwanger, N. Garmendia, A. Ghiglino, O. González, P.J. González, I. Madariaga, J.L. Muñoz, I. Rueda, F. Sordo Balbin, A. Vélez, D. de Cos
ESS Bilbao, Bilbao, Spain
V. Etxebarria, J. Portilla
University of the Basque Country, Faculty of Science and Technology, Bilbao, Spain
A. Garbayo
AVS, Eibar, Gipuzkoa, Spain
S. Jolly
UCL, London, United Kingdom
S.R. Lawrie, A.P. Letchford
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
J.K. Pozimski, P. Savage
Imperial College of Science and Technology, Department of Physics, London, United Kingdom

As part of the development of the ESS-Bilbao Accelerator in Spain, two different sets of radio frequency quadrupole (RFQ) models have been developed. On one hand, a set of four oxygen free high conductivity copper weld test models has been designed and manufactured, in order to test different welding methods as well as other mechanical aspects involved in the fabrication of the RFQ. On the other hand, a 352.2 MHz four vane RFQ cold model, with a length of 1 meter, has been designed and built in Aluminum. It serves as a good test bench to investigate the validity of different finite element analysis (FEA) software packages. This is a critical part, since the design of the final RFQ will be based on such simulations. The cold model also includes 16 slug tuners and 8 couplers/pick-up ports, which will allow to use the bead-pull perturbation method, by measuring the electric ﬁeld profile, Q-value and resonant modes. In order to investigate fabrication tolerances, the cold model also comprises a longitudinal test modulation in the vanes, which is similar to the one designed for the final RFQ.

THEPPB008

Inverse Compton Scattering Experiment in a Bunch Train Regime Using Nonlinear Optical Cavity

electron, photon, cavity, linac

3245

A.Y. Murokh, R.B. Agustsson, S. Boucher, P. Frigola, T. Hodgetts, A.G. Ovodenko, M. Ruelas, R. Tikhoplav
RadiaBeam, Santa Monica, USA
M. Babzien, M.G. Fedurin, T.V. Shaftan, V. Yakimenko
BNL, Upton, Long Island, New York, USA
I. Jovanovic
Penn State University, University Park, Pennsylvania, USA

Inverse Compton Scattering (ICS) is a promising approach towards achieving high intensity, directional beams of quasi-monochromatic gammas, which could offer unique capabilities in research, medical and security applications. Practicality implementation of ICS sources, however, depends on the ability to achieve high peak brightness (~0.1-1.0 ICS photons per interacting electron), while increasing electron-laser beam interaction rate to about 10,000 cps. We discuss the results of the initial experimental work at the Accelerator Test Facility (ATF) at BNL to demonstrate ICS interaction in a pulse-train regime, using a novel laser recirculation scheme termed Recirculation Injection by Nonlinear Gating (RING). Initial experimental results and outlook are presented.

THEPPB009

The CRISP Project – Building Synergies between Research Infrastructures

neutron, electron, ion, ion-source

3248

P. Antici
INFN/LNF, Frascati (Roma), Italy

Recently, the European Commission granted 12 M€ for a project aiming at the implementation of common solutions in infrastructures on the ESFRI* roadmap in the fields of physics, astronomy and analytical sciences. The objective of this initiative is to generate synergies in the development of components of interest for several infrastructures and thus promote efficiency and optimisation in the use of resources. The project, called "CRISP (Cluster of Research Infrastructures for Synergies in Physics) and started October 2011, gathers many major European large-scale infrastructures (CERN, XFEL, ESRF, ESS, FAIR, ILL, SKA, SLHC, SPIRAL-2, ELI, EuroFEL, ILC-Higrade etc). The generated synergies will be crucial to stimulate scientific and technological progress and to respond to the rapidly evolving user community. A brief overview of the different activities that are part of the project will be given, presenting the innovative approach of crossing boundaries between scientific disciplines and thus generating synergies.
*ESFRI stands for European Strategy Forum on Research Infrastructures

THPPC088

LLRF Control Algorithm for APEX

cavity, controls, LLRF, monitoring

3488

G. Huang, K.M. Baptiste, J.M. Byrd, L.R. Doolittle, F. Sannibale
LBNL, Berkeley, California, USA

Advanced photo-cathode experiment is an ongoing experiment of a high repetition rate low emittance VHF band gun experiment. A low level RF control and monitor subsystem is developed base on the 5 LLRF4 board. One of them is used for low level RF control and the other 4 are used as interlock and RF monitor at different point of the system. The laser is also controlled by the system to be synced to the RF system. This paper we summarize the control algorithm used in the system firmware.

THPPD048

15+ T HTS Solenoid for Muon Accelerator Program

solenoid, collider, power-supply

3617

Y. Shiroyanagi, R.C. Gupta, P.N. Joshi, H.G. Kirk, R.B. Palmer, S.R. Plate, W. Sampson, P. Wanderer
BNL, Upton, Long Island, New York, USA
D.B. Cline
UCLA, Los Angeles, California, USA
J. Kolonko, R.M. Scanlan, R.J. Weggel
Particle Beam Lasers, Inc., Northridge, California, USA

Funding: This work is supported by the U.S.Department of Energy under Contract No. DE-AC02-98CH10886 and SBIR contract DOE Grant Numbers DE-FG02-07ER84855 and DE-FG02- 08ER85037.
This paper will present the construction and test results of a ~10 T insert coil solenoid which is part of a proposed ~35 T solenoid being developed under a series of SBIR contracts involving collaboration between Particle Beam Lasers (PBL) and Brookhaven National Laboratory. The solenoid has an inner diameter of 25 mm, outer diameter of ~95 mm and a length of ~70 mm. It consists of 14 single pancake coils made from 4 mm wide 2G HTS conductor from SuperPower Inc., co-wound with a 4 mm wide, 0.025 mm thick stainless steel tape. These are paired into 7 double pancake coils. Each double pancake coil has been individually tested at 77 K before assembly in a complete solenoid. The solenoid is nearly ready for a high field test at ~4K.

THPPD079

Compact, High Current, High Voltage Solid State Switches for Accelerator Applications

high-voltage, pulsed-power, klystron, linac

3701

H.D. Sanders, S.C. Glidden
APP, Freeville, USA

Most switches used for high current, high voltage accelerator applications are vacuum or gas switches, such as spark gaps and thyratrons. Recently, high voltage IGBT based switches have become common, but are limited in current and are not compact. This paper will describe a compact, high current, high voltage solid state switch. These switches have been tested to 50kV, to greater than 12kA, to greater than 50kA/μs, to 360Hz, and to 3x10⁸ pulses, without failure. They have been used in accelerators to drive klystrons and kickers, and have been used as crowbars while offering advantages over thyratron switches for cost, lifetime, size and weight. The switches are based on series connected fast thyristors with 3cm² die in a 20cm² package. This package is more compact than TO-200 Puk sized devices, and does not require compression for proper operation. Each package is rated for 4kV, 14kA and 30kA/μs. One example, a 48kV switch which includes the trigger and snubber circuits, fits in a volume of 200mm x 85mm x 65mm, and requires only a fiber-optic trigger input. Such switches have been used on SRS and EMMA at Daresbury Laboratory in the UK, and at several US national laboratories.

THPPR042

Optimisation of an Inverse Compton Scattering Experiment with a Real Time Detection Scheme Based on a Radio Luminescent Screen and Comparison of the X-rays Beam Characteristics with Simulations

electron, photon, emittance, scattering

4068

A.S. Chauchat, JP. Brasile
TCS, Colombes, France
A. Binet, V. Le Flanchec, J-P. Nègre
CEA/DAM/DIF, Arpajon, France
J.-M. Ortega
LCP/CLIO, Orsay, Cedex, France

To optimize the detection of an 11-keV X-Ray beam produced by Inverse Compton Scattering at the ELSA facility*, with a 17 MeV electron beam and a 532 nm laser, we demonstrate the use of a very sensitive detection scheme, based on a radio luminescent screen used in the spontaneous emission regime. It has proven to be very sensitive and very effective to detect 11-keV X-Rays while rejecting the overall ambient noise produced in a harder spectral range. It allowed us to optimize the electron-photon interaction probability by observing in real time the effect of both beams transport parameters. We could then compare simulation results with experimental measurements that appear to be in good agreement.
*A.S. Chauchat et al. Instrumentation developments for production and characterization of Inverse Compton Scattering X-rays and first results with a 17 MeV electron beam, NIMA, V.622, I.1, P.129-135

THPPR044

A New Electron Beam Test Facility (EBTF) at Daresbury Laboratory for Industrial Accelerator System Development

electron, gun, FEL, vacuum

4074

P.A. McIntosh, D. Angal-Kalinin, S.R. Buckley, J.A. Clarke, A.R. Goulden, C. Hill, S.P. Jamison, J.K. Jones, A. Kalinin, J.W. McKenzie, K.J. Middleman, B.L. Militsyn, T.T. Ng, B.J.A. Shepherd, R.J. Smith, S.L. Smith, N. Thompson, A.E. Wheelhouse
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
N. Bliss, G.P. Diakun, A. Gleeson, T.J. Jones, B.G. Martlew, A.J. Moss, L. Nicholson, M.D. Roper, C.J. White
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom

Recent UK government funding has facilitated the implementation of a unique accelerator test facility which can provide enabling infrastructures targeted for the development and testing of novel and compact accelerator technologies, specifically through partnership with industry and aimed at addressing applications for medicine, health, security, energy and industrial processing. The infrastructure provision on the Daresbury Science and Innovation Campus (DSIC) will permit research into areas of accelerator technologies which have the potential to revolutionise the cost, compactness and efficiency of such systems. The main element of the infrastructure will be a high performance and flexible electron beam injector facility, feeding customised state-of-the-art testing enclosures and associated support infrastructure. The facility operating parameters and implementation status will be described, along with primary areas of commercialised technology development opportunities.

THPPR049

Study on Electron Microbeam Generation for MRT Based on Photo-cathode RF-Gun

gun, electron, cathode, radiation

4086

Y. Yoshida, K. Sakaue, M. Washio
RISE, Tokyo, Japan

We have been developing an MRT (Microbeam Radiation Therapy) based on Cs-Te photo cathode RF-Gun at Waseda University. MRT is proposed to treat tumor by using array of several micro-meter parallel beams. In this therapy, irradiated normal tissue repairs itself, by contrast, even a non-irradiated tumor tissue dies. In the other words, the microbeam enhances the radiation sensitivity difference between normal and tumor issues. Therefore, MRT is considered one of the most useful tumor therapies in the future. We have generated electron microbeam by tungsten collimator slit and analyzed their dose distribution in air and in the PMMA phantom. We have used radiochromic film called GAFCHROMIC dosimetry film type HD-810 to measure them. We have compared these experimental results with Monte Carlo simulation of the dose distribution using the EGS5 code. In this conference, we would like to report the electron microbeam procedure, optimization of irradiation condition, evaluation of microbeam specifications and future prospects.

THPPR057

Feasibility Study Gamma-induced Positron Annihilation Lifetime Spectroscopy in an Electron Storage Ring

positron, electron, target, storage-ring

4103

Y. Taira, H. Toyokawa
AIST, Tsukuba, Ibaraki, Japan
M. Adachi, M. Katoh, S. Tanaka
UVSOR, Okazaki, Japan
N. Yamamoto
Nagoya University, Nagoya, Japan

Funding: This work was supported by Grants-in-Aid for Scientific Research (22360297) and Grant-in-Aid for JSPS Fellows (235193).
Positron annihilation lifetime spectroscopy (PALS) has proved to be very sensitive tool to characterize materials and study defects. However PALS has been restricted to thin samples because of the limited range of positrons in materials. We have developed new techniques for PALS, in which laser Compton scattered (LCS) gamma rays are used to produce positrons inside materials via pair production. Ultra-short gamma ray pulse source* with pulse width of 5 ps (FWHM) generated by 90-degree collision LCS was applied to PALS for the first time. The short pulse width of the gamma-rays that is negligible compared to estimated positron lifetime (100 ps to ns range) is essential to PALS. The experiment was carried out at the UVSOR-II electron storage ring, a 750 MeV synchrotron light source. The positron annihilation lifetime, 199 ± 10 ps, in a bulk sample of lead was successfully measured by using the ultra-short gamma ray pulse.
* Y. Taira, et al., Nucl. Instr. And Meth. A 637 (2011) S116.

THPPR058

Pulse Radiolysis using Double-decker Femtosecond Electron Beam from a Photocathode RF Gun

electron, linac, gun, radiation

4106

K. Kan, T. Kondoh, K. Norizawa, A. Ogata, J. Yang, Y. Yoshida
ISIR, Osaka, Japan

Pulse radiolysis, which utilizes an electron bunch and a probe light (laser), is a powerful tool that can be used for an observation of ultrafast radiation-induced phenomena. The time resolution in pulse radiolysis depends on the electron bunch length, the probe-light width, and the timing jitter between the electron bunch and the probe light. In order to reduce the jitter, double-decker accelerator, in which separated laser was injected on a photocathode RF gun for a generation of synchronized double electron beams, was applied to pulse radiolysis. One electron beam was used as a pump source of a material, e. g. water, and another as a probe light at 800 nm wavelength with Cherenkov radiation.

THPPR059

Progress of the Equivalent Velocity Spectroscopy Method for Femtosecond Pulse Radiolysis by Pulse Rotation and Pulse Compression

electron, cathode, radiation, linac

4109

T. Kondoh, K. Kan, K. Norizawa, A. Ogata, S. Tagawa, J. Yang, Y. Yoshida
ISIR, Osaka, Japan
H. Kobayashi
KEK, Ibaraki, Japan

Femtosecond pulse radiolysis is developed for studies of electron beam induced ultra-fast reaction in matter. 98 fs electron pulse was generated by a photocathode RF gun LINAC with a magnetic bunch compressor. However for more fine time resolution, the Equivalent velocity spectroscopy (EVS) method is required to avoid degradation of time resolution caused by velocity difference between electron and analysing light in sample. In the EVS method, incident analysing light is oblique toward electron beam with an angle associated with refractive index of sample, and then, electron pulse is rotated toward the direction of travel to overlap with light pulse. In previous studies, pulse rotation had not been compatible with pulse compression. However, by oblique incident of light to the photocathode, pulse rotation was compatible with pulse compression, and the time resolution was improved by principle of the equivalent velocity spectroscopy.

THPPR065

High Flux Laser-Compton Scattered Gamma-ray Source by Compressed Nd:YAG Laser Pulse.

electron, photon, microtron, resonance

4124

I. Daito, R. Hajima, T. Hayakawa, Y. Hayashi, M. Kando, H. Kotaki, T. Shizuma
JAEA, Kyoto, Japan
H. Ohgaki
Kyoto University, Institute for Advanced Energy, Kyoto, Japan

A non-destructive detection system of nuclear materials hidden in cargo containers is under development in Japan Atomic Energy Agency and Kyoto University. The system is able to be used for the identification of isotopes of special nuclear material in a container by employing Nuclear Resonance Fluorescence triggered by mono-energetic Laser Compton Scattered (LCS) gamma-ray tuned at the energy of the nuclear resonance. One of the most important technologies for such system is generation of gamma-rays at a flux of 3 x10⁵ photon/s. In order to achieve this gamma-ray flux with a compact system, a pulse compression system for Nd:YAG laser based on Stimulated Brillouin Scattering (SBS) has been developed. The laser pulse with a duration of 10 ns (FWHM) from a commercially available Nd:YAG laser is compressed down to a few hundreds ps. As a feasibility study of the proposed system, 400 keV gamma-ray generation is performed at Kansai Photon Science Institute by using 150 MeV electron beam from microtron accelerator and compressed Nd:YAG laser. Experimental results of laser pulse compression and gamma-ray generation are presented.

THPPR068

Laser Compton Scattering X-rays as a Tool for K-edge Densitometry

photon, electron, scattering, radiation

4133

M. Titberidze, K. Chouffani
IAC, Pocatello, IDAHO, USA

There is a huge interest in bright and tunable X-ray sources. These sources can be used in various research fields, including medical, biological and industrial fields. Laser Compton Scattering (LCS) technique gives us possibility to generate tunable, quasi monochromatic and polarized X-ray beam. One of the applications of LCS is the detection and quantitative identification of special nuclear materials (SNM) using K-edge densitometry(KED)method. Our group was the first one who has used a quasi-monochromatic LCS source to carry out KED experiments. The experiments showed that LCS technique could be used for SNM detection and quantification.

THPPR070

Development of Multi-collision Laser Compton Scattering X-ray Source on the Basis of Compact S-band Electron Linac

electron, cavity, photon, linac

4139

R. Kuroda, M. Koike, E. Miura, Y. Taira, H. Toyokawa, K. Yamada, E. Yamaguchi
AIST, Tsukuba, Ibaraki, Japan
M. Kumaki
RISE, Tokyo, Japan

A compact hard X-ray source via laser Compton scattering is required for biological, medical and industrial science because it has many benefits about generated X-rays such as short pulse, quasi-monochromatic, energy tunability and good directivity. Our X-ray source is conventionally the single collision system between an electron pulse and a laser pulse. To increase X-ray yields, we have developed a multi-collision system with a multi-bunch electron beam and a laser optical cavity. The multi-bunch electron beam has already been generated from a Cs-Te photocathode rf gun system using a multi-pulse UV laser. The laser optical cavity have developed like a regenerative amplification including the collision point between the electron pulse and the laser pulse which is based on the Ti:Sa laser with a mode-locked frequency of 79.33 MHz. In this preliminary experiment, the modulated seed laser pulses were generated and leaded to the cavity, so that laser build-up amplification was performed in the cavity length of 3.78 m with two seed pulses. In this conference, we will describe the results of preliminary experiments for the multi-collision system and future plans.

FRXAA02

Advanced Solid State Lasers are Merging with Accelerators

cavity, acceleration, higher-order-mode, alignment

4157

A. Tünnermann, J. Limpert
Friedrich Schiller Universität, Jena, Germany
T. Schreiber
Fraunhofer-Institute for Applied Optics and Precision Engineering, Jena, Germany

In recent years, lasers have been developed to an essential tool in accelerator science, for acceleration and diagnostics. Novel applications require for high average power lasers in continuous and pulsed operation with diffraction limited beam quality. Lasers are known as sophisticated systems with a notorious poor efficiency. Most recently, rare-earth-doped fibers have established themselves as an attractive and power scalable solid-state laser concept. Using advanced large mode area fibers, in continuous-wave operation output powers in the 10 kW-regime with diffraction-limited beam quality at electrical to optical efficiencies of 30 percent have been demonstrated. In the pulsed regime average powers of the order of 1 kW even for femtosecond fiber laser systems have been reported. Coherent beam combination of these lasers allows for the generation of high peak power pulses at high repetition rates and output powers. In this contribution the state of the art in solid state laser technology operating at high average powers with inherent high efficiencies is reviewed. The prospects for future developments that will meet the demands set by the accelerator community will be discussed.

Slides FRXAA02 [11.729 MB]

FRXBB01

Femtosecond Electron Guns for Ultrafast Electron Diffraction

electron, gun, emittance, cathode

4170

J. Yang, K. Kan, T. Kondoh, N. Naruse, K. Tanimura, Y. Yoshida
ISIR, Osaka, Japan
J. Urakawa
KEK, Ibaraki, Japan

This talk should describe the development of electron guns for producing femtosecond electron pulses with low (<0.1 micron) emittance, for ultrafast electron diffraction. Comparisons should be made between the systems developed by groups in Asia, Europe and America, outlining any similarities and contrasts. The focus should be on the technology for generating, accelerating, and controlling the bunches, but some description of the science applications should also be included. Finally, prospects for future developments should be considered.

Slides FRXBB01 [7.004 MB]

FRYAP01

The Future of X-ray FELs

FEL, undulator, electron, linac

4180

H.-H. Braun
Paul Scherrer Institut, Villigen, Switzerland

Recent years have brought enormous progress with X-ray FELs. With LCLS and SACLA two facilities with quite different technological approaches have shown the feasibility of SASE FELs in the hard X-ray regime while the SASE FEL FLASH and the recently commissioned laser seeded FEL FERMI@ELETTRA provide coherent light beams of unprecedented brightness at EUV and soft X-ray wavelength. First user experiments at these facilities demonstrate the vast scientific potential of this new type of instrument and have accelerated and triggered R&D and planning for other facilities of its kind worldwide. Projects under construction or in advanced stage of planning are European XFEL, LCLS II, SwissFEL, PAL XFEL, Shanghai XFEL and NGLS. Worldwide R&D efforts for XFELs try to improve performance and reduce size and cost. Focuses are on injector, linac and undulator technologies as well as on FEL seeding methods.

Slides FRYAP01 [24.324 MB]