IPAC2014 - List of Keywords (FEL)

Paper	Title	Other Keywords	Page
MOYAA01	Innovative Ideas for Single-pass FELs	electron, operation, undulator, photon	12
	T. Hara RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
	SASE FELs are a powerful light source in short wavelengths from VUV to X-ray regions to investigate matters and phenomena. SASE was first experimentally obtained in 2000 at DESY TTF with an output wavelength of 10⁹ nm. Subsequently, FLASH, LCLS and SACLA have achieved lasing in VUV, soft X-rays and hard X-rays. Although SASE has already been widely used for many application experiments in broad scientific fields, its spiky spectrum and time structures due to the lack of longitudinal coherence sometimes become problematic. To improve its longitudinal coherence, various ideas have been proposed and some of them are already demonstrated experimentally, such as a self-seeded scheme, high-gain harmonic generation (HGHG) and echo-enabled harmonic generation (EEHG). There is also another direction of developments to enhance the capability and potentiality of SASE, for example short pulse generation and two-color lasing. This talk will review recent innovative ideas of short wavelength FELs together with their experimental results.
	Slides MOYAA01 [10.701 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOYAA01
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MOPRO015	Advances in Coherent Electron Cooling	electron, hadron, bunching, kicker	91
	V. Litvinenko, Y. Hao, Y.C. Jing, D. Kayran, G. Wang BNL, Upton, Long Island, New York, USA G.I. Bell, I.V. Pogorelov, B.T. Schwartz, A.V. Sobol, S.D. Webb Tech-X, Boulder, Colorado, USA D.L. Bruhwiler RadiaSoft LLC, Boulder, Colerado, USA A. Elizarov SUNY SB, Stony Brook, New York, USA D.F. Ratner SLAC, Menlo Park, California, USA O.A. Shevchenko BINP SB RAS, Novosibirsk, Russia
	This paper will be focused on advances and challenges in cooling of high-energy hadron – and potentially heavy lepton-beams. Such techniques are required to improve quality of hadron beams and for increasing the luminosity in hadron and electron-hadron colliders. In contrast with light leptons, which have very strong radiation damping via synchrotron radiation, the hadrons radiate very little (even in 7TeV LHC) and require additional cooling mechanism to control growth of their emittances. I will discuss the physics principles of revolutionary, but untested, technique: the coherent electron cooling (CeC). Further, current advances and novel CeC schemes will be presented as well as the status of preparation at Brookhaven National Laboratory for the CeC demonstration experiment.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO015
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MOPRI054	Status of the APEX Project at LBNL	gun, cathode, cavity, linac	727
	F. Sannibale, K.M. Baptiste, C.W. Cork, J.N. Corlett, S. De Santis, L.R. Doolittle, J.A. Doyle, D. Filippetto, G.L. Harris, G. Huang, H. Huang, R. Huang, T.D. Kramasz, S. Kwiatkowski, R.E. Lellinger, V. Moroz, W.E. Norum, C. F. Papadopoulos, G.J. Portmann, H.J. Qian, J.W. Staples, M. Vinco, S.P. Virostek, R.P. Wells, M.S. Zolotorev LBNL, Berkeley, California, USA R. Huang USTC/NSRL, Hefei, Anhui, People's Republic of China
	Funding: Work 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 (LBNL), consists in the development of an injector designed to demonstrate the capability of the VHF gun, a normal conducting 186 MHz RF gun operating in CW mode, to deliver the brightness required by X-ray FEL applications at MHz repetition rate. APEX is organized in 3 main phases where different aspects of the required performance are gradually demonstrated. The status and future plans for the project are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI054
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TUOCA02	Status of the Free Electron Laser User Facility FLASH	flattop, gun, laser, linac	938
	M. Vogt, B. Faatz, J. Feldhaus, K. Honkavaara, S. Schreiber, R. Treusch DESY, Hamburg, Germany
	FLASH, the Free Electron Laser User Facility at DESY (Hamburg, Germany), delivers high brilliance XUV and soft X-ray FEL radiation to photon experiments. After a shutdown to connect the second undulator beamline FLASH2 to the FLASH linac, re-commissioning of FLASH started in autumn 2013. The year 2014 is dedicated to FLASH1 user experiments. The commissioning of the FLASH2 beamline takes place in 2014 in parallel to FLASH1 operation.
	Slides TUOCA02 [9.156 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUOCA02
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TUOAB01	Computation of Eigenmodes in Long and Complex Accelerating Structures by Means of Concatenation Strategies	cavity, factory, HOM, coupling	947
	T. Flisgen, J. Heller, U. van Rienen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
	Funding: This research was partially funded by the EuCARD project which is co-funded by European Commission 7th in Framework Programme (FP7). The computation of eigenmodes for complex accelerating structures is a challenging and important task for the design and operation of particle accelerators. Discretizing long and complex structures to determine its eigenmodes leads to demanding computations typically performed on super computers. This contribution presents an application example of a method to compute eigenmodes and other parameters derived from these eigenmodes for long and complex structures using standard workstation computers. This is accomplished by the decomposition of the complex structure into several single segments. In a next step, the electromagnetic properties of the segments are described in terms of a compact state space model. Subsequently, the state space models of the single structures are concatenated to the full structure. The results of direct calculations are compared with results obtained by the concatenation scheme in terms of computational time and accuracy.
	Slides TUOAB01 [1.781 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUOAB01
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TUOCB03	Performance of Elliptical Polarization Undulators at TPS	undulator, polarization, multipole, photon	987
	T.Y. Chung, C.-H. Chang, C.H. Chang, J.C. Huang, C.-S. Hwang, J.C. Jan, F.-Y. Lin, C.Y. Wu NSRRC, Hsinchu, Taiwan
	Design, assembly, field shimming, and performance of APPLE-II type undulators in NSRRC are described in this article. Essentially, the mechanical error has been well controlled based on the optimize design and mechanical arts. Effectively initial sorting of permanent magnets is developed to minimize several adverse effects, such as magnetic inhomogeneities, no perfection geometry of blocks, and mechanical frame issue, those challenge the sorting expectation, especially for an adjusted polarization undulator. The sorting algorithm shows a quantitative prediction of magnetic field and is verified by measurement results. 2D virtual shimming algorithm has been developed to optimize field quality, including multipole, phase error, and particle trajectory. We describe the considering of each procedure and demonstrate the optimization together with measurement results.
	Slides TUOCB03 [1.503 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUOCB03
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TUPRO098	Design and Test of Dipole and Quadrupole Magnets for PAL-XFEL	dipole, quadrupole, multipole, operation	1271
	H.S. Suh, M.-H. Cho, Y.-G. Jung, H.-S. Kang, D.E. Kim, I.S. Ko, H.-G. Lee, S.B. Lee, B.G. Oh, K.-H. Park PAL, Pohang, Kyungbuk, Republic of Korea
	PAL-XFEL, currently under construction in Pohang, Korea, will consist of a 10 GeV linac, three hard X-ray branches and two soft X-ray branches. As the first phase of this project, one hard X-ray (HX1) and one soft X-ray (SX1) branches will be constructed. This facility requires 6 different families of dipole magnets, and 11 families of quadrupole magnets included steering functions. We are designing these magnets with the water cooling or the heat sink system now. In this presentation, we describe the modified design of the magnets for efficient manufacturing, and the magnetic and thermal analysis with the test results.
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TUPRI077	Stabilization of Mid-infrared FEL by Feedback Controls	feedback, electron, klystron, gun	1745
	H. Zen, M. Inukai, T. Kii, K. Masuda, M. Mishima, H. Negm, H. Ohgaki, K. Okumura, K. Takami, K. Torgasin, Y. Tsugamura, K. Yoshida Kyoto University, Kyoto, Japan
	A Mid-Infrared Free Electron Laser facility, KU-FEL* has been developed for energy related sciences. A beam position monitor and feedback system was introduced to stabilize the FEL output power and wavelength. The long term stability of FEL power and wavelength has been drastically improved by the feedback control. The developed feedback system and its performance will be reported in the conference. *H. Zen, et al., Infrared Physics & Technology, vol.51, 382-385.
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TUPRI079	Test Results of the Libera Sync 3 CW Reference Clock Transfer System	detector, controls, operation, instrumentation	1751
	P. Orel, E. Janezic, P.L. Lemut, S. Zorzut I-Tech, Solkan, Slovenia S. Hunziker, V. Schlott PSI, Villigen PSI, Switzerland
	The new Libera Sync 3 CW reference clock transfer system has been specifically designed to meet the strict requirements of the latest fourth generation light sources, such as the Swiss FEL. The system has been co-developed with the Paul Scherrer Institute (PSI). It has been produced and tested at Instrumentation Technologies (I-Tech) and later installed at PSI. In this article we give a general overview of the system and its functionalities. We also present a brief overview of the supporting products that have been developed in order to enable testing at the level of performance discussed. Finally, we focus on presenting some of the test results obtained at I-Tech and PSI showing the performance capabilities and limitations of the system.
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TUPRI107	Compact MTCA.4 Based Laser Synchronization	laser, timing, FPGA, hardware	1823
	M. Felber, L. Butkowski, H.T. Duhme, M. Fenner, C. Gerth, U. Mavrič, P. Peier, H. Schlarb, B. Steffen DESY, Hamburg, Germany T. Kozak, P. Prędki, K.P. Przygoda TUL-DMCS, Łódź, Poland
	In this paper we present a compact and efficient approach for laser synchronization based on MTCA.4 platform. Laser pulses are converted to the RF signals using a photo-diode detector. The RF section performs filtering, amplification and down-conversion of a narrowband, CW signal. The resulting IF signal is sampled by a high resolution digitizer on the AMC (Advanced Mezzanine Card) side and transported via point-to-point links to an adjacent AMC board. The processing electronics on this board drives a digital-to-analog converter on the rear-side. The analog signal is then filtered and amplified by a high voltage power amplifier which drives the piezo stretcher in the laser. Some preliminary results of laser to RF locking with such a scheme are presented.
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WEYB01	Large Dynamic Range Beam Diagnostics for High Average Current Electron LINACs	linac, diagnostics, brightness, optics	1900
	P.E. Evtushenko JLab, Newport News, Virginia, USA
	A number of applications is envisioned now for CW electron LINACs with high average current. A few examples are: driver-accelerators for the next generation of high average brightness SR sources, energy recovery LINACs to be used for frontier research in particle physics - search for dark matter candidate particles, industrial and defense applications. An average beam power of MWs is considered for such applications. Such machines will be required to operate simultaneously with high beam power and peak brightness comparable to the brightest electron beams generated in pulsed LINACs. Combining the high current advantages of storage rings and high peak brightness of LINACs will require such understanding and control of the beam dynamics that 10^-6 fraction of the beam current is taken in to account and controlled during the beam tuning. To make this possible a number of large dynamic range (LDR) (~10⁺⁶) beam diagnostics is under development and test at JLab FEL. Transverse and longitudinal LDR beam profile measurements can be used for LDR measurements of the phase space distribution and its evolution through the accelerator.
	Slides WEYB01 [4.581 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEYB01
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WEPRO008	A Beam-driven Microwave Undulator for FEL	undulator, wakefield, electron, linac	1956
	A. Kanareykin, C.-J. Jing, P. Schoessow Euclid TechLabs, LLC, Solon, Ohio, USA S. Baturin LETI, Saint-Petersburg, Russia A. Zholents ANL, Argonne, Ilinois, USA
	Funding: DOE SBIR Microwave waveguides can in principle be used for undulators with periods less than 1 cm. Intensive work has been done on the recently proposed design that operates at the HE11 hybrid mode of a corrugated waveguide; successful experimental results have been reported recently [S.Tantawi Talk at POSIPOL 2012]. In this presentation we propose a beam driven design for an undulator based on an electron bunch train powering a microwave or mm waveguide. The drive bunch train propagates towards the undulating beam inside a dielectric loaded structure or corrugated waveguide generating high power RF. The “smart” waveguide design and a proper bunch spacing of the electron drive beam train provide single mode generation of the high magnitude undulating field that gives an undulator parameter in the range of K~1 for a high frequency device.* *A. Zholents, HBEB Workshop, Puerto-Rico, 2013.
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WEPRO022	Modal Analysis of Helical Undulator Radiation In Cylindrical Waveguide	radiation, undulator, vacuum, linac	1989
	T.L. Vardanyan, M. Ivanyan, V. Sahakyan, A.V. Tsakanian, G.S. Zanyan CANDLE SRI, Yerevan, Armenia
	The coherent radiation of the relativistic electron beam with helical orbit in circular waveguide is studied. The radiation field configuration is obtained using modal expansion technique. For short electron bunches the coherent part of radiation is evaluated. The coherent radiation effects on the bunch performance are analyzed.
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WEPRO031	Design and Commissioning of the FLASH2 Undulators	undulator, controls, operation, vacuum	2007
	A. Schöps, O. Bilani, T. Ramm, M. Tischer, S. Tripathi, P. Vagin DESY, Hamburg, Germany
	This paper reports about aspects of design, manufacturing, and commissioning of the 12 FLASH2 variable gap undulator segments. The accuracy of gap drive and encoder systems was tested by magnetic measurements; changes in the phase error proved to be a highly sensitive probe to verify a reproducibility of 1 μm. After magnetic tuning of the IDs, the remaining gap dependence in the field integrals could be successfully compensated by corrector coils. Inconsiderate handling of components during assembling necessitated an elaborate demagnetisation process before the tuning could start.
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WEPRO032	Phase Shifters for the FLASH2 FEL	undulator, electron, operation, quadrupole	2010
	M. Tischer, P. Neumann, A. Schöps, P. Vagin DESY, Hamburg, Germany
	The FLASH2 SASE undulator section consists of 12 IDs. Each of them is followed by an intersection component comprising a phase shifter and various parts for diagnostics and beam steering. The phase shifter is a compact and simple electromagnetic chicane and has to assure constructive interference of the radiation of adjacent undulators for all wavelengths. The magnetic performance, field errors and the hysteresis behavior have been investigated and were found to be within the required accuracy. The results are discussed in relation to the undulator conditions. From these data tables for steering the phase shifter current as function of undulator gap were derived and implemented in the control system.
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WEPRO039	Status of PAL-XFEL Undulator Program	undulator, controls, radiation, electron	2029
	D.E. Kim, H.-S. Kang, W.W. Lee, K.-H. Park PAL, Pohang, Kyungbuk, Republic of Korea M.-H. Cho, I.S. Ko POSTECH, Pohang, Kyungbuk, Republic of Korea S. Karabekyan, J. Pflüger XFEL. EU, Hamburg, Germany
	Pohang Accelerator Laboratory (PAL) is developing 10 GeV, 0.1 nm SASE based FEL for high power, short pulse X-ray coherent photon sources named PAL-XFEL. At the first stage PAL-XFEL needs two undulator lines for photon source. PAL is developing undulator magnetic structure based on EU-XFEL design. Recently, the hard X-ray undulator changed its minimum magnetic gap to 8.3 mm from the previous 7.2 mm to alleviate the wake field impact, and to increase the allowances for the re alignment. Accordingly, the period is also changed from 24.4 mm to 26.0 mm to generate 0.1 nm at 10 GeV electron energy. In this report, the modification efforts and the progress on the prototyping of hard x-ray undulator system will be presented.
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WEPRO040	Field Measurement Facility for PAL-XFEL Undulators	undulator, controls, laser, software	2032
	K.-H. Park, Y.-G. Jung, D.E. Kim, S.N. Kim, I.S. Ko, B.H. Lee, H.-G. Lee, M.S. Lee, S.B. Lee, H.S. Suh, C.W. Sung PAL, Pohang, Kyungbuk, Republic of Korea
	Pohang Accelerator Laboratory (PAL) is developing the SASE based FEL for X-ray coherent photon sources. The PAL developed the prototype undulator that was 5.0 m magnetic length. The PAL has constructed the undulator field measurement facility to confirm the field qualities of the XFEL undulators in the assembly building. The temperature stability of the measurement rooms was controlled within ±0.1°C. Two field measurement benches that included Hall probe scan, flip coil and stretched wire system were installed and evaluated their performances. The field profile of the prototype undulator was characterized and shimmed using the installed measurement system. This paper described the field measurement facility with the performance test results of the two benches.
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WEPRO048	A Concept of a Universal Superconducting Undulator	undulator, simulation, electron, storage-ring	2050
	Y. Ivanyushenkov ANL, Argonne, Ilinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357. Tiny round electron beams of free-electron lasers and relatively new diffraction-limited storage rings make possible utilization of electromagnetic helical undulators based on double-helical windings. It has been understood for a while that a coaxial pair of double-helical windings can generate helical as well as planar magnetic fields. Such a coil structure can potentially be realized with superconducting windings thus forming the concept of a universal superconducting undulator (Universal SCU). An example of a possible universal SCU for the recently suggested Advanced Photon Source multi-bend achromat storage ring is given in this paper. The results of the magnetic simulation together with initial cryogenic considerations are presented. D.F. Alferov, Yu.A. Bashamakov, E. G. Bessonov, Sov. J. Tech. Phys. 21(11), (1976) 1408.
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WEPRO053	All-optical Free Electron Lasers using Travelling-wave Thomson Scattering	electron, laser, undulator, scattering	2065
	K. Steiniger, M.H. Bussmann, A.D. Debus, A. Irman, A. Jochmann, R.G. Pausch, U. Schramm Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiation Physics, Dresden, Germany T.E. Cowan HZDR, Dresden, Germany
	In Travelling-Wave Thomson Scattering (TWTS) the pulse front of a high-power, short-pulse laser is tilted and the dispersion of the pulse is controlled in such a way that electrons can interact over a long distance with a quasi-monochromatic electromagnetic wave. We present a complete three dimensional analytic time-dependent description of the TWTS field and use this description to derive an analytic FEL equation that shows that TWTS indeed provides for an all-optical FEL. We further derive conditions for optimum operation of the TWTS FEL, showing that EUV and XUV FEL sources are in reach using Petawatt lasers and conventional few-hundred MeV electron sources. Future laser-wakefield accelerators could potentially drive all-optical TWTS-FELs in the X-ray and beyond. TWTS itself is optimum to provide full flexibility in terms of the wavelength and bandwidth of the scattered radiation, allowing for application-optimized, highly-brilliant Thomson Scattering sources for a broad range of wavelengths from the EUV to the gamma ray spectral region.
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WEPRO094	Synchrotron Radiation Test Validations of European XFEL MCP-based Detectors at DORIS Beamline BW1	detector, photon, radiation, ion	2180
	E. Syresin, A.Yu. Grebentsov, A.V. Shabunov, N.I. Zamiatin JINR, Dubna, Moscow Region, Russia R. Basta, T. Fiala, P. Hedbavny Vakuum Praha, Prague, Czech Republic O.I. Brovko JINR/VBLHEP, Moscow, Russia W. Freund, J. Grünert, H. Sinn XFEL. EU, Hamburg, Germany D. Novikov, M.V. Yurkov DESY, Hamburg, Germany
	Radiation detectors based onμchannel plates (MCP) are planned for installation at the European XFEL. Main purpose of these detectors is searching a signature of lasing and further fine tuning of the FEL process. Detectors operate in a wide dynamic range from the level of spontaneous emission to the saturation level (between a few nJ and 25 mJ), and in a wide wavelength range from 0.05 nm to 0.4 nm for SASE1 and SASE2, and from 0.4 nm to 4.43 nm for SASE3. The SR tests validation of the MCP-based detector applied for XFEL lines SASE1 and SASE2 were performed at the DORIS beamline BW1 at SR with photon energy of 8.5-12.4 keV. The absolute measurements of a photon pulse energy for hard X-ray radiation were performed with application of MCP and photodiode detectors. Pulse-to-pulse photon energy measurements with MCPs and silicon photo detector were done with 192 ns and 96 ns repetition intervals. The SR beam imaging measurement at X-ray irradiation was performed at test validation experiments.
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WEPME083	VELA: A New Accelerator Technology Development Platform for Industry	electron, cavity, target, experiment	2471
	P.A. McIntosh, D. Angal-Kalinin, R.K. Buckley, S.R. Buckley, J.A. Clarke, P.A. Corlett, B.D. Fell, A.R. Goulden, C. Hill, F. Jackson, S.P. Jamison, J.K. Jones, L.B. Jones, A. Kalinin, L. Ma, J.W. McKenzie, K.J. Middleman, B.L. Militsyn, A.J. Moss, T.C.Q. Noakes, Y.M. Saveliev, D.J. Scott, B.J.A. Shepherd, R.J. Smith, S.L. Smith, T.T. Thakker, A.E. Wheelhouse, P.H. Williams STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom N. Bliss, G. Cox, G.P. Diakun, A. Gleeson, T.J. Jones, K. Robertson, M.D. Roper, E. Snedden STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom S.T. Boogert Royal Holloway, University of London, Surrey, United Kingdom N.J. Boulding FMB Oxford, Oxford, United Kingdom A. Lyapin JAI, Egham, Surrey, United Kingdom E.J. Morton CXR Ltd, Guildford, United Kingdom
	The Versatile Electron Linear Accelerator (VELA) facility will provide enabling infrastructures targeted at the development and testing of novel and compact accelerator technologies, specifically through partnership with industry and aimed at addressing applications in medicine, health, security, energy and industrial processing. The facility has now been commissioned at Daresbury Laboratory and the facility is now being actively utilised by industrial groups who are able to take advantage of the variable electron beam parameters available on VELA to either demonstrate new techniques and/or processes or otherwise develop new technologies for future commercial realisation. Examples of which to be presented include; demonstration of a new cargo scanning process, characterisation of novel, high performance beam position monitors, as well as other technology development applications.
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WEPRI044	Final Structure and Design Parameters of TARLA RF System	electron, rf-amplifier, LLRF, controls	2577
	Ö. Karslı, A.A. Aksoy, C. Kaya, İ.B. Koc, E.Ç. Polat, O. Yavaş Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey M. Doğan Dogus University, Istanbul, Turkey S. Özkorucuklu Istanbul University, Istanbul, Turkey
	Funding: Work supported by Turkish Ministry of Development (Grant No: DPT2006K-120470) Turkish Accelerator and Radiation Laboratory in Ankara (TARLA) is an oscillator mode IR-FEL facility which is under construction since 2011. ELBE licensed superconducting modules housing TESLA RF cavities have been manufacturing for one year and the first module will be delivered in 2015. He Cryogenic System has also started to be manufacturing at similar time with the accelerator structures. It will be delivered in 2014. High Power RF amplifiers are started to tender procedures and delivery time is planning as 2015. The installation of high power transmission lines have to be completed at the same time with the delivery date of HPRF amplifiers to test the cavities and amplifiers. In this study, the final structural design of high power RF transmission lines and design parameters of RF amplifiers for TARLA is discussed. On behalf of TARLA Collaboration, www.tarla.org.tr
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THYA01	Control and Application of Beam Microbunching in High Brightness Linac-driven Free Electron Lasers	laser, impedance, electron, radiation	2789
	G.V. Stupakov SLAC, Menlo Park, California, USA
	The remarkable properties of coherent radiation from free-electron lasers (FELs) are due to the current modulation in the beam with the modulation period equal to the radiation wavelength. This modulation is developed as a result of a beam instability when the beam propagates in a long FEL undulator, and requires a beam with a high-peak current, small emittance and a small energy spread. Unfortunately the same beam qualities make it a subject to a so-called microbunching instability at a much longer scale than the radiation wavelength. It is driven by the space charge and CSR impedances in the machine and develops during the beam acceleration in the linac, compression, and transport to the undulator. If not controlled, the microbunching instability influences dramatically the FEL performance and in the worst case can even ruin the lasing. In the presentation we will review the mechanism behind the microbunching instability, the suppression methods used in existing facilities as well as possible future developments and concepts.
	Slides THYA01 [5.631 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THYA01
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THPPA01	FEL R&D Initiatives at the SLAC National Accelerator Laboratory	undulator, electron, laser, free-electron-laser	2842
	A. Marinelli SLAC, Menlo Park, California, USA
	The successful lasing of the linac coherent light source in 2009, the first x-ray free-electron laser (xFEL) in the world, has opened a new era for x-ray photon science. The unprecedented intensity and coherence of the LCLS photon pulses have enabled groundbreaking experiments in a wide variety of fields ranging from coherent x-ray imaging to molecular and atomic physics. Despite the success of x-ray free-electron lasers, there is a steady push to extend and improve their capabilities fueled by the users' demands for new modes of operation and more precise photon and electron diagnostics. In my talk I will present several R&D initiatives at the SLAC National Accelerator Laboratory geared towards improving the performance and extending the capabilities of x-ray FELs. In particular I will focus on the spectral manipulation of FELs and our recent development of the multibunch and multicolor x-ray FEL modes at LCLS as well as our demonstration of the longitudinal space-charge amplifier as a broadband coherent light source at the NLCTA test accelerator.
	Slides THPPA01 [10.793 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPPA01
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THPPA02	Gersch Budker Prize Presentation	klystron, collider, linear-collider, electron	2846
	T. Shintake OIST, Onna-son, Okinawa, Japan
	SACLA: SPring-8 Angstrom Compact free-electron Laser, previously called XFEL/SPring-8, which is based on electron accelerator technology developed at SCSS project, in which C-band high gradient linear accelerator provides stable driving beams. Looking back upon 20 years R&D on C-band accelerator, I would like to give some advises to young scientists on doing research. The developed C-band accelerator is now providing 8 GeV electron beams at SACLA X-ray FEL in daily operation with the world best energy stability among these large scale machines.
	Slides THPPA02 [17.649 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPPA02
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THPRO003	Progress of the LUNEX5 demonstator Project	electron, operation, undulator, laser	2856
	M.-E. Couprie, C. Benabderrahmane, P. Berteaud, C. Bourassin-Bouchet, F. Bouvet, L. Cassinari, L. Chapuis, J. Daillant, M. Diop, M.E. El Ajjouri, C. Evain, C. Herbeaux, N. Hubert, M. Labat, P. Lebasque, A. Lestrade, A. Loulergue, P. Marchand, O. Marcouillé, J.L. Marlats, C. Miron, P. Morin, A. Nadji, F. Polack, F. Ribeiro, J.P. Ricaud, P. Roy, K. Tavakoli, M. Valléau, D. Zerbib SOLEIL, Gif-sur-Yvette, France S. Bielawski, E. Roussel, C. Szwaj PhLAM/CERCLA, Villeneuve d'Ascq Cedex, France B. Carré, D. Garzella CEA/DSM/DRECAM/SPAM, Gif-sur-Yvette, France X. Davoine CEA/DAM/DIF, Arpajon, France N. Delerue LAL, Orsay, France G. Devanz CEA/DSM/IRFU, France A. Dubois, J. Lüning CCPMR, Paris, France G. Lambert, R. Lehé, V. Malka, A. Rousse, C. Thaury LOA, Palaiseau, France C. Madec, A. Mosnier CEA/IRFU, Gif-sur-Yvette, France
	LUNEX5 (free electron Laser Using a New accelerator for the Exploitation of X-ray radiation of 5th generation) aims at investigating the production of short, intense, coherent pulses in the 40-4 nm spectral range [1]. It comprises two types of accelerators connected to a single Free Electron Laser (FEL) for advanced seeding configurations (seeding with High order Harmonic in Gas, echo). A 400 MeV superconducting Linear Accelerator, adapted for studies of advanced FEL schemes, will enable future upgrade towards high repetition rate and multi-user operation by splitting part of the macropulse to different FEL lines. A 0.4 - 1 GeV Laser Wake Field Accelerator (LWFA) [2] will also be qualified by the FEL application. After the Conceptual Design Report, R&D has been launched on different sub components. Following transport theoretical studies of longitudinal and transverse manipulation of a LWFA electron beam enabling to provide theoretical amplification, a test experiment is under preparation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO003
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THPRO004	Study of the CLIO FEL in the Far-infrared in a Partially Guided Mode	vacuum, cavity, undulator, simulation	2859
	J.-M. Ortega, J.P. Berthet, F. Glotin, R. Prazeres LCP/CLIO, Orsay, Cedex, France
	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 unity. The main limitation comes from the diffraction of the optical beam due to the finite size of the vacuum chamber of the undulator. A solution is to use this chamber as a waveguide by adaptating the radius of curvature of the cavity mirrors to this regime. Then, as has been shown before* a minimum appears in the spectrum that can be produced by the FEL. We discuss the physical mechanism of this particular regime and compare it to experiments using vacuum chambers of different tranverse sizes. A good agreement is found with results of simulations and with a simple analytical formula. * Analysis of the periodic power gaps observed in the tuning range of FELs with a partial waveguide, R. Prazeres, F. Glotin, J.-M. Ortega, Phys. Rev. STAB12, 010701 (2009)
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO004
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THPRO007	Beam-based Alignment in the European XFEL SASE1	undulator, radiation, quadrupole, simulation	2867
	H. Jin, W. Decking, T. Limberg DESY, Hamburg, Germany
	The European X-ray Free Electron Laser (E-XFEL) provides an ultra-short and high-brilliant photon pulses of spatially coherent X-rays with wavelengths down to 0.05 nm by using three undulator systems. Within these undulator systems, the orbit trajectory is required to be straight to a few micron over each gain length, so that the photon beam is capable of overlapping efficiently with the electron beam. However, this requirement is not obtainable with ordinary mechanical alignment methods. For this reason, a beam-based alignment (BBA) method using BPM readings of different beam energies is applied to the E-XFEL SASE1 undulators. In this report, we describe the BBA simulation for SASE1 including alignment errors of quadrupoles and BPMs. After correction, the desired range of the orbit trajectory is attained with high confidence. In addition, to identify the reliability of an aligned orbit trajectory acquired from the BBA simulation, we present here the SASE FEL radiation simulation, in which we observe a slight decrease of radiation energy and power.
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THPRO008	Obtaining High Degree of Circular Polarization at X-ray FELs via a Reverse Undulator Taper	undulator, radiation, bunching, polarization	2870
	E. Schneidmiller, M.V. Yurkov DESY, Hamburg, Germany
	Baseline design of a typical X-ray FEL undulator assumes a planar configuration which results in a linear polarization of the FEL radiation. However, many experiments at X-ray FEL user facilities would profit from using a circularly polarized radiation. As a cheap upgrade one can consider an installation of a short helical (or cross-planar) afterburner, but then one should have an efficient method to suppress powerful linearly polarized background from the main undulator. In this paper we propose a new method for such a suppression: an application of the reverse taper in the main undulator. We discover that in a certain range of the taper strength, the density modulation (bunching) at saturation is practically the same as in the case of non-tapered undulator while the power of linearly polarized radiation is suppressed by orders of magnitude. Then strongly modulated electron beam radiates at full power in the afterburner. Considering SASE3 undulator of the European XFEL as a practical example, we demonstrate that soft X-ray radiation pulses with peak power in excess of 100 GW and an ultimately high degree of circular polarization can be produced. Phys. Rev. ST-AB 16(2013)110702
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO008
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THPRO009	Harmonic Lasing in X-ray FELs	undulator, electron, photon, operation	2873
	E. Schneidmiller, M.V. Yurkov DESY, Hamburg, Germany
	Contrary to nonlinear harmonic generation, harmonic lasing in a high-gain FEL can provide much more intense, stable, and narrow-band FEL beam which is easier to handle if the fundamental is suppressed. We perform a parametrization of the solution of eigenvalue equation for lasing at odd harmonics, and present explicit expression for FEL gain length, taking into account all essential effects. We propose and discuss methods for suppression of the fundamental. We also suggest a combined use of harmonic lasing and lasing at the retuned fundamental wavelength in order to reduce bandwidth and to increase brilliance of X-ray beam. We discover that in a part of the parameter space, corresponding to the operating range of soft X-ray beamlines of X-ray FEL facilities, harmonics can grow faster than the fundamental. We suggest that harmonic lasing can be widely used in the existing or planned X-ray FEL facilities. LCLS after a minor modification can lase at the 3rd harmonic up to the photon energy of 25-30 keV providing multi-gigawatt power level. At the European XFEL the harmonic lasing would allow to extend operating range up to 100 keV, to reduce bandwidth and increase brilliance.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO009
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THPRO010	Analysis of Operation of Harmonic Lasing Self-seeded FEL	undulator, simulation, radiation, electron	2876
	E. Schneidmiller, M.V. Yurkov DESY, Hamburg, Germany
	Harmonic lasing self-seeded FEL holds great potential for significant improvement of the the longitudinal coherence of the radiation. A gap-tunable undulator is divided into two parts by setting two different undulator parameters such that the first part is tuned to a sub-harmonic of the second part. Harmonic lasing occurs in the exponential gain regime in the first part of the undulator, also the fundamental stays well below saturation. In the second part of the undulator the fundamental mode is resonant to the wavelength, previously amplified as the harmonic. The amplification process proceeds in the fundamental mode up to saturation. In this case the bandwidth is defined by the harmonic lasing (i.e. it is reduced by a significant factor depending on harmonic number) but the saturation power is still as high as in the reference case of lasing at the fundamental in the whole undulator, i.e. the spectral brightness increases. Application of the undulator tapering in the deep nonlinear regime would allow to generate higher peak powers approaching TW level. The scheme is illustrated with the parameters of the European XFEL.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO010
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THPRO011	Investigation of the Coherence Properties of the Radiation at FLASH	radiation, emittance, electron, undulator	2879
	E. Schneidmiller, M.V. Yurkov DESY, Hamburg, Germany
	We present the results of the studies of coherence properties of the radiation from FLASH for fundamental harmonic and higher odd harmonics. General overview of the parameter space is performed including peak current, emittance, and external focusing. The results of our studies show that present configuration of FLASH free electron laser is not optimal for providing ultimate quality of the output radiation. We find that the physical origin of the problem is mode degeneration. The way for improving quality of the radiation is proposed.
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THPRO013	FERMI Status Report	laser, electron, linac, experiment	2885
	M. Svandrlik, E. Allaria, F. Bencivenga, C. Callegari, F. Capotondi, D. Castronovo, P. Cinquegrana, M. Coreno, R. Cucini, I. Cudin, G. D'Auria, M.B. Danailov, R. De Monte, G. De Ninno, P. Delgiusto, A.A. Demidovich, S. Di Mitri, B. Diviacco, A. Fabris, R. Fabris, W.M. Fawley, M. Ferianis, E. Ferrari, P. Finetti, L. Fröhlich, P. Furlan Radivo, G. Gaio, D. Gauthier, F. Gelmetti, L. Giannessi, M. Kiskinova, S. Krecic, M. Lonza, N. Mahne, C. Masciovecchio, M. Milloch, F. Parmigiani, G. Penco, L. Pivetta, O. Plekan, M. Predonzani, E. Principi, L. Raimondi, P. Rebernik Ribič, F. Rossi, L. Rumiz, C. Scafuri, C. Serpico, P. Sigalotti, C. Spezzani, C. Svetina, M. Trovò, A. Vascotto, M. Veronese, R. Visintini, D. Zangrando, M. Zangrando Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	FERMI, the seeded Free Electron Laser (FEL) located at the Elettra laboratory in Trieste, Italy, consists of two FEL lines. The FEL-1 facility, covering the wavelength range between 20 and 100 nm, was officially opened to external users. The shorter wavelength range, between 20 and 4 nm, is covered by the FEL-2 line, a double stage cascade operating in the “fresh bunch injection” mode, which is still under commissioning. We will report on the different FEL-1 operation modes that can be offered for users and assess the performance of the facility. The progress in the commissioning of FEL-2 will then be addressed, in particular reporting the performance attained at the lower wavelength limit; this aspect is of great interest for the user’s community of the FERMI seeded FEL since it allows to carry out experiments below the carbon K-edge.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO013
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THPRO016	Stable Generation of High Power Self-seeded XFEL at SACLA	radiation, electron, undulator, photon	2888
	T. Inagaki, N. Adumi, T. Fukui, T. Hara, Y. Inubushi, T. Ishikawa, H. Kimura, R. Kinjo, H. Maesaka, Y. Otake, H. Tanaka, T. Tanaka, K. Togawa, M. Yabashi RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan S. Goto, T.K. Kameshima, T. Ohata, K. Tono JASRI/SPring-8, Hyogo, Japan T. Hasegawa, S. Tanaka SES, Hyogo-pref., Japan A. Miura, H. Ohashi, H. Yamazaki Japan Synchrotron Radiation Research Institute (JASRI/SPring-8), Hyogo, Japan
	A self-seeded XFEL system using a transmitted beam under Bragg diffraction has been developed at the first compact XFEL facility SACLA in order to generate a brilliant single-mode XFEL with high temporal coherence. High stability and unique beam characteristics of SACLA should significantly contribute to achieve reliable, high-quality seeded XFEL operation. In particular, the short-pulse property that has been achieved in routine operation enables us to switch SASE and seeded mode quickly, without changing the electron beam parameters. This is also useful for delivering different modes to multiple beamlines simultaneously. In the test experiments carried out in autumn 2013, spectral narrowing was observed at 10 keV using diamond 400 reflection. Systematic optimization on beam properties is now in progress towards experimental use of seeded XFELs in summer 2014. This talk gives the overview of the plan, achieved results and ongoing R&D.
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THPRO017	Comparison of the Detection Performance of Three Nonlinear Crystals for the Electro-optic Sampling of a FEL-THz Source	laser, detector, lattice, damping	2891
	B. Wu, L. Cao, Q. Fu, P. Tan, Y.Q. Xiong HUST, Wuhan, People's Republic of China
	The detector of a FEL-THz source at HUST is now in the physical design stage. The electro-optic (EO) sampling method will be employed for the coherent detection. The performances of three widely used EO crystals will be evaluated and compared numerically in the time domain detection: zinc telluride (ZnTe), gallium arsenide (GaAs) and gallium phosphide (GaP). The phase matching properties are analyzed to find the appropriate probe wavelength. The EO detection response is calculated to select the suitable crystal thickness and to discuss the detection ability of each crystal.
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THPRO018	Electron-Magnetic-Phase Mixing in a Linac-driven FEL to Suppress Microbunching in the Optical Regime and Below	linac, electron, laser, radiation	2894
	S. Di Mitri, S. Spampinati Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy H.-S. Kang PAL, Pohang, Kyungbuk, Republic of Korea S. Spampinati Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Control of microbunching instability is a fundamental requirement in modern high brightness electron linacs, in order to prevent malfunction of beam optical diagnostics and contamination in the generation of coherent radiation, such as free electron lasers. We present experimental control and suppression of microbunching instability-induced optical transition radiation by means of particles’ longitudinal phase mixing in a magnetic chicane. In presence of phase mixing, the intensity of the beam-emitted coherent optical transition radiation is reduced by one order of magnitude and brought to the same level provided, alternatively, by beam heating. The experimental results are in agreement with particle tracking and analytical evaluations of the instability gain. A discussion of applications of magnetic phase mixing to the generation of quasi-cold high-brightness ultra-relativistic electron beams is finally given. S. Di Mitri and S. Spampinati, Phys. Rev. Lett. 112, 134802 (2014)
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THPRO020	Linac Lattice Optimization for PAL-XFEL Hard X-ray FEL Line	linac, lattice, simulation, emittance	2900
	H. Yang, J.H. Han, H.-S. Kang, I.S. Ko PAL, Pohang, Kyungbuk, Republic of Korea
	Funding: This work is supported by MSIP, Korea. PAL-XFEL is designed to generate 1 – 0.06-nm FEL in hard x-ray FEL line. The linac for hard x-ray generates 10-GeV, 200-pC, and 3-kA electron beam. It consists of accelerating columns, three bunch compressors, an X-band linearizer, and dog-leg line. We conduct ELEGANT simulations to obtain the optimized lattice for hard x-ray line. The candidates of the optimized lattice are obtained by Multi-Objective Genetic Algorithm (MOGA) whose objectives are the FEL saturation power and length. These are evaluated with their error tolerances. Error tolerances are obtained by two methods of error simulations. First, the linear interpolation method is conducted in order to determine the machine tolerance. Also, we find out the dominant machine parameters to increase the beam jitter by this method. Second, the error simulations with random errors of machine parameters are conducted to verify the results of the linear interpolation method and calculate beam jittering levels. In this paper, we present the details of the optimized linac lattice for hard x-ray FEL. Also, we present the procedure of the linac lattice optimization.
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THPRO022	JINR Powerful Laser Driver Applied for FEL Photoinjector	laser, radiation, electron, ion	2906
	E. Syresin, N. Balalykin, M.A. Nozdrin, G. Shirkov, G.V. Trubnikov JINR, Dubna, Moscow Region, Russia E. Gacheva, E. Khazanov, G. Luchinin, S. Mironov, A. Poteomkin, V. Zelenogorsky IAP/RAS, Nizhny Novgorod, Russia
	Funding: The work is funded by the German Federal Ministry of education and Research, project 05K10CHE. The JINR develops a project of superconducting linear accelerator complex, based on a superconducting linear accelerator, for applications in nanoindustry, mainly for extreme ultraviolet lithography at a wavelength of 13.5 nm using kW-scale Free Electron Laser (FEL) light source. The application of kW-scale FEL source permits realizing EUV lithography with 22 nm, 16 nm resolutions and beyond. JINR-IAP collaboration constructed powerful laser driver applied for photoinjector of FEL linear accelerator which can be used for EUV lithography. To provide FEL kW-scale EUV radiation the photoinjector laser driver should provide a high macropulse repetition rate of 10 Hz, a long macropulse time duration of 0.8 ms and 8000 pulses per macropulse. The laser driver operates at wavelength of 260-266 nm on forth harmonic in the mode locking on base of Nd ions or Yb ions The laser driver micropulse energy of 1.6 uJ should provide formation of electron beam in FEL photoinjector with the bunch charge about 1 nC.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO022
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THPRO023	Methods for the Optimization of a Tapered Free-Electron Laser	wiggler, radiation, electron, simulation	2909
	A.W.L. Mak, F. Curbis, S. Werin MAX-lab, Lund, Sweden
	In a free-electron laser (FEL), the technique of wiggler tapering enables the sustained growth of radiation power beyond the initial saturation. With the goal to develop an X-ray FEL in the terawatt power regime, it is important to utilize this technique and optimize the taper profile, giving the wiggler parameter as a function of the distance along the wiggler line. This work examines two methods of optimization, which are based on the theoretical analysis by Kroll, Morton and Rosenbluth (KMR). Using the numerical simulation code GENESIS, the methods are applied to a case for the possible future FEL at the MAX IV Laboratory in Lund, Sweden, as well as a case for the LCLS-II.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO023
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THPRO025	Conceptual Design of a X-FEL Facility using CLIC X-band Accelerating Structure	linac, klystron, simulation, gun	2914
	A.A. Aksoy, O. Yavaş Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey D. Angal-Kalinin, J.A. Clarke Cockcroft Institute, Warrington, Cheshire, United Kingdom M.J. Boland SLSA, Clayton, Australia G. D'Auria, S. Di Mitri, C. Serpico Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy M. Doğan Dogus University, Istanbul, Turkey T.J.C. Ekelöf, R.J.M.Y. Ruber, V.G. Ziemann Uppsala University, Uppsala, Sweden W. Fang, Q. Gu SINAP, Shanghai, People's Republic of China A. Latina, D. Schulte, S. Stapnes, I. Syratchev, W. Wuensch CERN, Geneva, Switzerland Z. Nergiz Nigde University, Nigde University Science & Art Faculty, Nigde, Turkey
	Within last decade a linear accelerating structure with an average loaded gradient of 100 MV/m at 12 GHz has been demonstrated in the CLIC study. Recently, it has been proposed to use the CLIC structure to drive an FEL linac. In contrast to CLIC the linac would be powered by klystrons not by a drive beam. The main advantage of this proposal is achieving the required energies in a very short distance, thus the facility would be rather compact. In this study, we present the conceptual design parameters of a facility which could generate laser photon pulses covering the range of 1-75 Angstrom. Shorter wavelengths could also be reached with slightly increasing the energy.
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THPRO026	Design Parameters and Current Status of the TARLA Project	electron, undulator, linac, radiation	2918
	A.A. Aksoy, Ö. Karslı, C. Kaya, E. Kazancı, O. Yavaş Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey P. Arıkan Gazi University, Faculty of Arts and Sciences, Teknikokullar, Ankara, Turkey S. Özkorucuklu Istanbul University, Istanbul, Turkey
	Funding: Work is supported by Ministry of Development of Turkey with Grand No: DPT2006K-120470 The Turkish Accelerator and Radiation Laboratory in Ankara (TARLA) will operate two InfraRed Free Electron Lasers (IR-FEL) covering the range of 3-250 microns. The facility will consist of an injector fed by a thermionic triode gun with two-stage RF bunch compression, two superconducting accelerating ELBE modules operating at continuous wave (CW) mode and two independent optical resonator systems with different undulator period lengths. The electron beam will also be used to generate Bremsstrahlung radiation. In this paper, we discuss design goals of the project and present status and road map of the project. On behalf of TARLA Team
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THPRO027	Turkish Accelerator Center: The Status and Roadmap	electron, linac, proton, factory	2921
	A.A. Aksoy, O. Yavaş, H.D. Duran Yıldız Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey B. Akkus, S. Özkorucuklu, L.S. Yalcin Istanbul University, Istanbul, Turkey H. Aksakal, Z. Nergiz Nigde University, Nigde University Science & Art Faculty, Nigde, Turkey E. Algin Eskisehir Osmangazi University, Eskisehir, Turkey O. Cakir Ankara University, Faculty of Sciences, Ankara, Turkey
	Funding: Ankara University Turkish Accelerator Center (TAC) Project has started with support of the Ministry of Development (MD) of Turkey under the coordination of Ankara University. TAC is an inter-university collaboration with 12 Turkish Universities. An IR FEL facility (TARLA) based on Sc linac with 15-40 MeV energy under construction in Ankara as the first facility of TAC. It is expected that the TARLA facility will be commissioning in 2017. In addition to the TARLA, it is planned that Turkish Accelerator Center will include a third generation synchrotron radiation facility based on 1-3 GeV electron synchrotron (TAC SR), a fourth generation SASE FEL facility based on up to 5 GeV electron linac (TAC SASE FEL), a multi-purpose proton accelerator facility with 3 MeV-2 GeV beam energy (TAC PAF) and an electron-positron collider as a super charm factory (TAC PF). Construction phase of the proposed GeV scale accelerator facilities will cover next decade. In this presentation, main goals and road map of Turkish Accelerator Center will be explained. (http://thm.ankara.edu.tr) *On behalf of TAC collaboration
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THPRO030	Developments in CLARA Accelerator Design and Simulations	wakefield, simulation, electron, undulator	2930
	S. Spampinati Cockcroft Institute, Warrington, Cheshire, United Kingdom D. Angal-Kalinin, A.D. Brynes, D.J. Dunning, J.K. Jones, K.B. Marinov, J.W. McKenzie, B.L. Militsyn, N. Thompson, P.H. Williams STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom I.P.S. Martin DLS, Oxfordshire, United Kingdom
	We present recent developments in the accelerator design of CLARA (Compact Linear Accelerator for Research and Applications), the proposed UK FEL test facility at Daresbury Laboratory. Updates on the electron beam simulations and code comparisons including wakefields are described. Simulations of the effects of geometric wakefields in the small-aperture FEL undulator are shown, as well as further simulations on potential FEL experiments using chirped beams. We also present the results of simulations on post-FEL diagnostics.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO030
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THPRO031	Short Pulses THz FEL for the Oxford Accelerator Science Laboratory	radiation, cavity, gun, undulator	2934
	T. Chanwattana, R. Bartolini, A. Seryi JAI, Oxford, United Kingdom R. Bartolini DLS, Oxfordshire, United Kingdom E. Tsesmelis CERN, Geneva, Switzerland
	The Accelerator Science Laboratory (ASL) is under development at the John Adams Institute in Oxford with the aim of fostering advanced accelerator concepts and applications. The option to install a short pulse THz FEL based on a conventional RF accelerator driven by a RF photocathode gun is being investigated. This report presents the concept of the facility, the accelerator physics and FEL studies and engineering integration in the University physics department.
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THPRO032	Studies on LPWA-based Light Sources driven by a Transverse Gradient Undulator	undulator, laser, electron, simulation	2937
	T. Chanwattana, R. Bartolini, A. Seryi JAI, Oxford, United Kingdom R. Bartolini DLS, Oxfordshire, United Kingdom
	The Accelerator Science Laboratory (ASL) is under development at the John Adams Institute in Oxford with the aim of fostering advanced accelerator concepts and applications. The option to install a LPWA based light source driven by a transverse gradient undulator is being investigated. This report presents the accelerator physics, FEL studies and the performance expected from such a facility.
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THPRO035	Improving and Maintaining FEL Beam Stability of the LCLS	feedback, timing, high-voltage, undulator	2943
	F.-J. Decker, A.L. Benwell, W.S. Colocho, Z. Huang, A. Krasnykh, J.R. Lewandowski, T.J. Maxwell, J. Sheppard, J.L. Turner SLAC, Menlo Park, California, USA
	Funding: *Work supported by U.S. Department of Energy, Contract DE-AC02-76SF00515. The beam stability of the Linac Coherent Light Source (LCLS) has seen many improvements over the years and has matured to a state where progress is slow and maintaining the best stability is becoming the main challenge. Single sources which are identified by various means contribute to only about 10 to 20% of the whole jitter power, meaning that their elimination gives only a small improvement of 5 to 10%. New sources need to be identified fast. Especially slow variations of a few seconds to minutes time scale are often hidden and partially corrected by feedback systems. A few episodes of increased jitter have shown the limitations of some of the feedback systems. Stability for all dimensions, transverse, longitudinal, and intensity are presented.
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THPRO038	Energy-Silenced HGHG	laser, bunching, electron, space-charge	2946
	E. Hemsing, G. Marcus, A. Marinelli SLAC, Menlo Park, California, USA D. Xiang Shanghai Jiao Tong University, Shanghai, People's Republic of China
	We study the effect of longitudinal space charge on the correlated energy spread of a relativistic beam that has been microbunched for the emission of high harmonic radiation. We show that, in the case of microbunching induced by a laser modulator followed by a dispersive chicane, longitudinal space charge forces can act to significantly reduce the induced energy spread of the beam without a reduction in the harmonic bunching content. This effect may significantly relax constraints on the harmonic number achievable in HGHG FELs, which are otherwise limited by the induced energy spread from the laser.
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THPRO039	Model-independent Description of Shot-noise, Amplification and Saturation	bunching, electron, undulator, simulation	2949
	Y.C. Jing, V. Litvinenko, G. Wang BNL, Upton, Long Island, New York, USA V. Litvinenko Stony Brook University, Stony Brook, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. High-gain FEL is one of many electron-beam instabilities, which have a number of common features linking the shot noise, the amplification and the saturation. In this paper we present a new, model-independent description of the interplay between these effects and derivation of a simple formula determining the saturation and maximum attainable gain in such instabilities. Application of this model-independent formula to FEL is compared with FEL theory and simulations. We describe limitations resulting from these finding for FEL amplifiers used for seeded FELs and for Coherent electron Cooling.
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THPRO044	Report on Gun Conditioning Activities at PITZ in 2013	gun, cathode, cavity, vacuum	2962
	M. Otevřel, P. Boonpornprasert, J.D. Good, M. Groß, I.I. Isaev, D.K. Kalantaryan, M. Khojoyan, G. Kourkafas, M. Krasilnikov, D. Malyutin, D. Melkumyan, T. Rublack, F. Stephan, G. Vashchenko DESY Zeuthen, Zeuthen, Germany G. Asova INRNE, Sofia, Bulgaria P. Boonpornprasert, S. Rimjaem Chiang Mai University, Chiang Mai, Thailand F. Brinker, K. Flöttmann, S. Lederer, B. Marchetti, S. Schreiber DESY, Hamburg, Germany Ye. Ivanisenko PSI, Villigen PSI, Switzerland M.A. Nozdrin JINR, Dubna, Moscow Region, Russia G. Pathak Uni HH, Hamburg, Germany D. Richter BESSY GmbH, Berlin, Germany
	Recently three RF guns were prepared at the Photo Injector Test Facility at DESY, location Zeuthen (PITZ) for their subsequent operation at FLASH and the European XFEL. The gun 3.1 is a previous cavity design and is currently installed and operated at FLASH, the other two guns 4.3 and 4.4 were of the current cavity design and are dedicated to serve for the start-up of the European XFEL photo-injector. All three cavities had been dry-ice-cleaned prior their conditioning and hence showed low dark current levels. The lowest dark current level – as low as 60μA at 65MV/m field amplitude – has been observed for the gun 3.1. This paper reports in details about the conditioning process of the most recent gun 4.4. It informs about experience gained at PITZ during establishing of the RF conditioning procedure and provides a comparison with the other gun cavities in terms of the dark currents. It also summarizes the major setup upgrades, which have affected the conditioning processes of the cavities.
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THPRO050	Study of a THz/VUV Free Electron Laser Facility in Taiwan	laser, radiation, undulator, linac	2980
	N.Y. Huang, M.C. Chou, C.-S. Hwang, W.K. Lau, A.P. Lee NSRRC, Hsinchu, Taiwan A. Chao, J. Wu SLAC, Menlo Park, California, USA C.H. Chen, Y.-C. Huang NTHU, Hsinchu, Taiwan X.M. Yang DICP, Dalian, People's Republic of China
	A free electron laser (FEL) facility aimed for VUV and THz radiation is being studied at National Synchrotron Radiation Research Center (NSRRC) in Taiwan. Strong consideration has been given to minimize the cost by making maximum use of existing hardware at NSRRC. One unique consideration is to use an existing undulator for the dual functions of the THz radiator and the modulator of a HGHG section. Design emphasizes versatility of operation and beam quality control and compensation of nonlinearities, with a vision that it will allow as much as possible future upgrades as well as later R&D of FEL physics. The polarization control of the THz radiation provides novel application for the users. The facility is to be housed in the existing 38-m by 5-m tunnel of the TPS Linac Test Laboratory.
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THPRO051	Cavity Design for a S-Band Photoinjector RF Gun with 400 Hz Repetition Rate	cavity, gun, cathode, emittance	2983
	J.W. McKenzie, L.S. Cowie, P. Goudket, B.L. Militsyn STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom G. Burt Cockcroft Institute, Lancaster University, Lancaster, United Kingdom T.J. Jones STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom V.V. Paramonov RAS/INR, Moscow, Russia
	As part of the design of CLARA (Compact Linear Accelerator for Research and Applications), the proposed UK FEL test facility at Daresbury Laboratory, a high repetition rate S-band photoinjector RF gun is being developed. This gun will be able to operate at up to 400 Hz repetition rate in single bunch mode. We present the initial cavity design including its optimisation for the beam dynamics of CLARA. We also present the initial cooling design for the cavity which will enable the high repetition rates to be achieved.
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THPRO074	Characterization of the Longitudinal Wakefields in the MAX IV Linac	linac, wakefield, simulation, gun	3050
	O. Karlberg, F. Curbis, S. Thorin, S. Werin MAX-lab, Lund, Sweden
	In the second part of 2014, the 3GeV linac at the MAX IV laboratory will enter its commissioning stage. Equipped with two guns, the linac will act as a full energy injector for the two storage rings and at the same time provide high brightness pulses to a Short Pulse Facility (SPF). Compression in the linac is done in two double achromats with fixed R56 that relies upon the RF phase introduced energy chirp, which in this case is strongly enhanced by the longitudinal wakefields. Since the longitudinal wakefields plays a major role in the compression and bunch shaping they need to be carefully investigated during the commissioning. In this proceeding we will discuss a measurement technique that will be used during commissioning to characterize the longitudinal wakefields and their precise effects on e.g. the bunch shape and the energy spread. Predictions obtained from particle tracking will be presented.
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THPRO077	The New FREIA Laboratory for Accelerator Development	cryomodule, controls, linac, cryogenics	3059
	R.J.M.Y. Ruber, A.K. Bhattacharyya, T.J.C. Ekelöf, K. Fransson, K.J. Gajewski, V.A. Goryashko, L. Hermansson, M. Jacewicz, T. Lofnes, M. Olvegård, R. Santiago Kern, R. Wedberg, R.A. Yogi, V.G. Ziemann Uppsala University, Uppsala, Sweden D.S. Dancila, A. Rydberg Uppsala University, Department of Engineering Sciences, Uppsala, Sweden
	The FREIA laboratory is a Facility for REsearch Instrumentation and Accelerator Development at Uppsala University, Sweden constructed recently to develop and test accelerator components. Initially it will develop the RF system for the spoke cavities of the ESS linac and test prototype spoke cavities at nominal RF power. For this purpose we installed a helium liquefaction plant, a versatile horizontal test cryostat and two 352 MHz RF power stations, one based on two tetrodes and the other on solid state technology. Beyond these developments FREIA will house a neutron generator and plans for a THz FEL are under discussion. FREIA is embedded in the Ångström physics, chemistry and engineering campus at Uppsala in close proximity to mechanical workshops, clean room with electron microscopes, tandem accelerator and the biomedical center.
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THPME081	Plans for an Australian XFEL Using a CLIC X-band Linac	storage-ring, synchrotron, linac, emittance	3424
	M.J. Boland, T.K. Charles, R.T. Dowd, G. LeBlanc, Y.E. Tan, K.P. Wootton, D. Zhu SLSA, Clayton, Australia R. Corsini, A. Grudiev, A. Latina, D. Schulte, S. Stapnes, I. Syratchev, W. Wuensch CERN, Geneva, Switzerland
	Preliminary plans are presented for a sub-Angstrom wavelength XFEL at the Australian Synchrotron light source site. The design is based around a 6 GeV x-band linac from the CLIC Project. One of the motivations for the design is to have an XFEL co-located on the site with existing storage ring based synchrotron light source. The desire and ability of the Australian photon science community to win beamtime on existing XFELs has lead to this design study to plan for a future machine in Australia. The technology choice is also driven by the Australian participation in the CLIC Collaboration and the local HEP community.
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THPME109	EOS at CW Beam Operation at ELBE	electron, laser, operation, diagnostics	3492
	Ch. Schneider, M. Gensch, M. Kuntzsch, P. Michel, W. Seidel HZDR, Dresden, Germany P.E. Evtushenko JLab, Newport News, Virginia, USA Ç. Kaya Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey A. Shemmary, N. Stojanovic DESY, Hamburg, Germany
	The ELBE accelerator is a super conduction electron cw machine located at the Helmholtz Center Dresden Rossendorf Germany with 1 mA current, now tested for up to 2 mA. Besides other important diagnostics for setting up the machine for user beam time and further improvement of the machine – a THz source is momentary under commissioning – a EOS measuring station for bunch length measurements is locate right behind the second super conducting Linac. Measuring with a crystal in the vicinity of an up to 2 mA cw beam implies higher beam loss and also higher radiation exposure of the crystal and hence also a safety risk for the UHV conditions of the super conducting cavities in the case of crystal damage. Therefore the EOS measuring principle is adapted to larger measuring distances and also for beam requirements with lower bunch charge at ELBE. A description of the setup, considerations of special boundary conditions and as well results for 13 MHz cw beam operation are presented.
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THPME142	Design of the Beam Profile Monitors for THz Source Based FEL	controls, linac, target, LabView	3584
	J. Liu, P. Lu, B.G. Sun, K. Tang, J.G. Wang, J. Xu, Y.L. Yang, Z.R. Zhou USTC/NSRL, Hefei, Anhui, People's Republic of China
	Design of the Beam Profile Monitors for THz Source Based FEL* J. Liu, P. Lu, B. G. Sun#, Y. J. Pei, Y. L. Yang, Z.R. Zhou, J. G. Wang, K. Tang, J. Xu NSRL, School of Nuclear Science and Technology, University of Science and Technology of China, Hefei 230029, P. R. China Abstract To meet requirements of high performance THz-FEL, a compact FEL facility was proposed. In order to characterize the beam, some beam profile monitors were designed. There are four flags for beam profiles in Linac，one pop-in monitor for high precision beam profile inside a small-gap undulator, and two screens to measure the beam energy spread and emittance of Linac. On one hand, we need to use software to control the position of these profile monitors, on the other hand, we need screens to display the results. This paper describes how to design and control these monitors, as well as how to measure the beam parameter.
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THPME156	Convergent Cherenkov Radiation from Dielectric Targets	target, radiation, optics, vacuum	3626
	S.N. Galyamin, E.S. Belonogaya, A.V. Tyukhtin, V.V. Vorobev Saint-Petersburg State University, Saint-Petersburg, Russia E.S. Belonogaya LETI, Saint-Petersburg, Russia
	Funding: Work was supported by the Grant of the President of Russian Federation (No. 273.2013.2). Cherenkov radiation is a convenient tool for charged particle detection and bunch diagnostics. However, due to the complexity of real radiator geometry, different approximate techniques are elaborated for investigation of excited radiation. Here we develop recently reported* approximate method for calculating Cherenkov radiation of a charge flying near a dielectric target having two main boundaries (the first interacts with a charge field and the second mainly refracts a generated radiation). We focus on cases where the radiation outside the target is convergent and use two methods for field investigation: ray optical technique and aperture integration technique. First, we deal with the case of a conical target with a vacuum channel. Under certain conditions, this radiation is concentrated near the line being the symmetry axis of the target. Second, we find the specific shape of the target that concentrates radiation in a small vicinity of given point (focus). Such targets can be used for improvement of detectors and bunch diagnostics systems based on Cherenkov effect. A.P. Potylitsyn et al., Diffraction Radiation from Relativistic Particles, STMP 239 (Springer, 2010). *E.S. Belonogaya, A.V. Tyukhtin, S.N. Galyamin, Phys. Rev. E, 87, 043201 (2013).
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THPME170	Prospects for Longitudinal Phase-space Measurements at the MAX IV Linac	linac, electron, simulation, extraction	3665
	F. Curbis, O. Karlberg, S. Thorin, S. Werin MAX-lab, Lund, Sweden
	Knowing the longitudinal phase space of an electron beam is one of the most important and crucial issues in short-pulses linacs. To achieve this task expensive and rather complicated setups (like transverse deflecting cavities) are usually implemented. The MAX IV 3 GeV linac will be used to inject into two rings and to drive a short pulse facility. Nevertheless, a more deep understanding of the beam quality would be useful especially in view of an upgrade as FEL driver. Another interesting aspect is to evaluate how the double-achromat bunch compressors are performing. We are studying how to implement off-phase acceleration: last part of the linac will be set at zero-crossing phase and the transfer line to the 3 GeV ring could be used as energy spectrometer to retrieve the bunch profile. In the present configuration of the MAX IV linac this procedure will allow to check the bunch length after the first bunch compressor. Since it is work in progress, in this contribution we present a sketch of the measurement and the feasibility of the method will be explored by means of simulations.
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THPME184	Improvement of Beam Imaging Systems through Optics Propagation Simulations	simulation, radiation, optics, photon	3709
	B. Bolzon, T. Lefèvre, S. Mazzoni CERN, Geneva, Switzerland A.S. Aryshev KEK, Ibaraki, Japan B. Bolzon, C.P. Welsch The University of Liverpool, Liverpool, United Kingdom B. Bolzon, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom P. Karataev, K.O. Kruchinin Royal Holloway, University of London, Surrey, United Kingdom P. Karataev, K.O. Kruchinin JAI, Egham, Surrey, United Kingdom
	Optical Transition Radiation (OTR) is emitted when a charged particle crosses the interface between two media with different dielectric properties. It has become a wide-spread method for beam profile measurements. However, there are no tools to simulate the propagation of the OTR electric field through an optical system. Simulations using ZEMAX have been performed in order to quantify optical errors, such as aberrations, diffraction, depth of field and misalignment. This paper focuses on simulations of vertically polarized OTR photons with the aim of understanding what limits the resolution of realistic beam imaging systems.
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THPRI073	Achieving Higher Energies via Passively Driven X-band Structures	cavity, impedance, electron, linac	3933
	T. Sipahi, S. Biedron, S.V. Milton CSU, Fort Collins, Colorado, USA
	Due to their higher intrinsic shunt impedance X-band accelerating structures significant gradients with relatively modest input powers, and this can lead to more compact particle accelerators. At the Colorado State University Accelerator Laboratory (CSUAL) we would like to adapt this technology to our 1.3 GHz L-band accelerator system using a passively driven 11.7 GHz traveling wave X-band configuration that capitalizes on the high shunt impedances achievable in X-band accelerating structures in order to increase our overall beam energy in a manner that does not require investment in an expensive, custom, high-power X-band klystron system. Here we provide the design details of the X-band structures that will allow us to achieve our goal of reaching the maximum practical net potential across the X-band accelerating structure while driven solely by the beam from the L-band system.
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MOYAA01

Innovative Ideas for Single-pass FELs

electron, operation, undulator, photon

12

T. Hara
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan

SASE FELs are a powerful light source in short wavelengths from VUV to X-ray regions to investigate matters and phenomena. SASE was first experimentally obtained in 2000 at DESY TTF with an output wavelength of 10⁹ nm. Subsequently, FLASH, LCLS and SACLA have achieved lasing in VUV, soft X-rays and hard X-rays. Although SASE has already been widely used for many application experiments in broad scientific fields, its spiky spectrum and time structures due to the lack of longitudinal coherence sometimes become problematic. To improve its longitudinal coherence, various ideas have been proposed and some of them are already demonstrated experimentally, such as a self-seeded scheme, high-gain harmonic generation (HGHG) and echo-enabled harmonic generation (EEHG). There is also another direction of developments to enhance the capability and potentiality of SASE, for example short pulse generation and two-color lasing. This talk will review recent innovative ideas of short wavelength FELs together with their experimental results.

Slides MOYAA01 [10.701 MB]

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MOPRO015

Advances in Coherent Electron Cooling

electron, hadron, bunching, kicker

91

V. Litvinenko, Y. Hao, Y.C. Jing, D. Kayran, G. Wang
BNL, Upton, Long Island, New York, USA
G.I. Bell, I.V. Pogorelov, B.T. Schwartz, A.V. Sobol, S.D. Webb
Tech-X, Boulder, Colorado, USA
D.L. Bruhwiler
RadiaSoft LLC, Boulder, Colerado, USA
A. Elizarov
SUNY SB, Stony Brook, New York, USA
D.F. Ratner
SLAC, Menlo Park, California, USA
O.A. Shevchenko
BINP SB RAS, Novosibirsk, Russia

This paper will be focused on advances and challenges in cooling of high-energy hadron – and potentially heavy lepton-beams. Such techniques are required to improve quality of hadron beams and for increasing the luminosity in hadron and electron-hadron colliders. In contrast with light leptons, which have very strong radiation damping via synchrotron radiation, the hadrons radiate very little (even in 7TeV LHC) and require additional cooling mechanism to control growth of their emittances. I will discuss the physics principles of revolutionary, but untested, technique: the coherent electron cooling (CeC). Further, current advances and novel CeC schemes will be presented as well as the status of preparation at Brookhaven National Laboratory for the CeC demonstration experiment.

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MOPRI054

Status of the APEX Project at LBNL

gun, cathode, cavity, linac

727

F. Sannibale, K.M. Baptiste, C.W. Cork, J.N. Corlett, S. De Santis, L.R. Doolittle, J.A. Doyle, D. Filippetto, G.L. Harris, G. Huang, H. Huang, R. Huang, T.D. Kramasz, S. Kwiatkowski, R.E. Lellinger, V. Moroz, W.E. Norum, C. F. Papadopoulos, G.J. Portmann, H.J. Qian, J.W. Staples, M. Vinco, S.P. Virostek, R.P. Wells, M.S. Zolotorev
LBNL, Berkeley, California, USA
R. Huang
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: Work 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 (LBNL), consists in the development of an injector designed to demonstrate the capability of the VHF gun, a normal conducting 186 MHz RF gun operating in CW mode, to deliver the brightness required by X-ray FEL applications at MHz repetition rate. APEX is organized in 3 main phases where different aspects of the required performance are gradually demonstrated. The status and future plans for the project are presented.

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TUOCA02

Status of the Free Electron Laser User Facility FLASH

flattop, gun, laser, linac

938

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

FLASH, the Free Electron Laser User Facility at DESY (Hamburg, Germany), delivers high brilliance XUV and soft X-ray FEL radiation to photon experiments. After a shutdown to connect the second undulator beamline FLASH2 to the FLASH linac, re-commissioning of FLASH started in autumn 2013. The year 2014 is dedicated to FLASH1 user experiments. The commissioning of the FLASH2 beamline takes place in 2014 in parallel to FLASH1 operation.

Slides TUOCA02 [9.156 MB]

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TUOAB01

Computation of Eigenmodes in Long and Complex Accelerating Structures by Means of Concatenation Strategies

cavity, factory, HOM, coupling

947

T. Flisgen, J. Heller, U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany

Funding: This research was partially funded by the EuCARD project which is co-funded by European Commission 7th in Framework Programme (FP7).
The computation of eigenmodes for complex accelerating structures is a challenging and important task for the design and operation of particle accelerators. Discretizing long and complex structures to determine its eigenmodes leads to demanding computations typically performed on super computers. This contribution presents an application example of a method to compute eigenmodes and other parameters derived from these eigenmodes for long and complex structures using standard workstation computers. This is accomplished by the decomposition of the complex structure into several single segments. In a next step, the electromagnetic properties of the segments are described in terms of a compact state space model. Subsequently, the state space models of the single structures are concatenated to the full structure. The results of direct calculations are compared with results obtained by the concatenation scheme in terms of computational time and accuracy.

Slides TUOAB01 [1.781 MB]

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TUOCB03

Performance of Elliptical Polarization Undulators at TPS

undulator, polarization, multipole, photon

987

T.Y. Chung, C.-H. Chang, C.H. Chang, J.C. Huang, C.-S. Hwang, J.C. Jan, F.-Y. Lin, C.Y. Wu
NSRRC, Hsinchu, Taiwan

Design, assembly, field shimming, and performance of APPLE-II type undulators in NSRRC are described in this article. Essentially, the mechanical error has been well controlled based on the optimize design and mechanical arts. Effectively initial sorting of permanent magnets is developed to minimize several adverse effects, such as magnetic inhomogeneities, no perfection geometry of blocks, and mechanical frame issue, those challenge the sorting expectation, especially for an adjusted polarization undulator. The sorting algorithm shows a quantitative prediction of magnetic field and is verified by measurement results. 2D virtual shimming algorithm has been developed to optimize field quality, including multipole, phase error, and particle trajectory. We describe the considering of each procedure and demonstrate the optimization together with measurement results.

Slides TUOCB03 [1.503 MB]

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TUPRO098

Design and Test of Dipole and Quadrupole Magnets for PAL-XFEL

dipole, quadrupole, multipole, operation

1271

H.S. Suh, M.-H. Cho, Y.-G. Jung, H.-S. Kang, D.E. Kim, I.S. Ko, H.-G. Lee, S.B. Lee, B.G. Oh, K.-H. Park
PAL, Pohang, Kyungbuk, Republic of Korea

PAL-XFEL, currently under construction in Pohang, Korea, will consist of a 10 GeV linac, three hard X-ray branches and two soft X-ray branches. As the first phase of this project, one hard X-ray (HX1) and one soft X-ray (SX1) branches will be constructed. This facility requires 6 different families of dipole magnets, and 11 families of quadrupole magnets included steering functions. We are designing these magnets with the water cooling or the heat sink system now. In this presentation, we describe the modified design of the magnets for efficient manufacturing, and the magnetic and thermal analysis with the test results.

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TUPRI077

Stabilization of Mid-infrared FEL by Feedback Controls

feedback, electron, klystron, gun

1745

H. Zen, M. Inukai, T. Kii, K. Masuda, M. Mishima, H. Negm, H. Ohgaki, K. Okumura, K. Takami, K. Torgasin, Y. Tsugamura, K. Yoshida
Kyoto University, Kyoto, Japan

A Mid-Infrared Free Electron Laser facility, KU-FEL* has been developed for energy related sciences. A beam position monitor and feedback system was introduced to stabilize the FEL output power and wavelength. The long term stability of FEL power and wavelength has been drastically improved by the feedback control. The developed feedback system and its performance will be reported in the conference.
*H. Zen, et al., Infrared Physics & Technology, vol.51, 382-385.

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TUPRI079

Test Results of the Libera Sync 3 CW Reference Clock Transfer System

detector, controls, operation, instrumentation

1751

P. Orel, E. Janezic, P.L. Lemut, S. Zorzut
I-Tech, Solkan, Slovenia
S. Hunziker, V. Schlott
PSI, Villigen PSI, Switzerland

The new Libera Sync 3 CW reference clock transfer system has been specifically designed to meet the strict requirements of the latest fourth generation light sources, such as the Swiss FEL. The system has been co-developed with the Paul Scherrer Institute (PSI). It has been produced and tested at Instrumentation Technologies (I-Tech) and later installed at PSI. In this article we give a general overview of the system and its functionalities. We also present a brief overview of the supporting products that have been developed in order to enable testing at the level of performance discussed. Finally, we focus on presenting some of the test results obtained at I-Tech and PSI showing the performance capabilities and limitations of the system.

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TUPRI107

Compact MTCA.4 Based Laser Synchronization

laser, timing, FPGA, hardware

1823

M. Felber, L. Butkowski, H.T. Duhme, M. Fenner, C. Gerth, U. Mavrič, P. Peier, H. Schlarb, B. Steffen
DESY, Hamburg, Germany
T. Kozak, P. Prędki, K.P. Przygoda
TUL-DMCS, Łódź, Poland

In this paper we present a compact and efficient approach for laser synchronization based on MTCA.4 platform. Laser pulses are converted to the RF signals using a photo-diode detector. The RF section performs filtering, amplification and down-conversion of a narrowband, CW signal. The resulting IF signal is sampled by a high resolution digitizer on the AMC (Advanced Mezzanine Card) side and transported via point-to-point links to an adjacent AMC board. The processing electronics on this board drives a digital-to-analog converter on the rear-side. The analog signal is then filtered and amplified by a high voltage power amplifier which drives the piezo stretcher in the laser. Some preliminary results of laser to RF locking with such a scheme are presented.

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WEYB01

Large Dynamic Range Beam Diagnostics for High Average Current Electron LINACs

linac, diagnostics, brightness, optics

1900

P.E. Evtushenko
JLab, Newport News, Virginia, USA

A number of applications is envisioned now for CW electron LINACs with high average current. A few examples are: driver-accelerators for the next generation of high average brightness SR sources, energy recovery LINACs to be used for frontier research in particle physics - search for dark matter candidate particles, industrial and defense applications. An average beam power of MWs is considered for such applications. Such machines will be required to operate simultaneously with high beam power and peak brightness comparable to the brightest electron beams generated in pulsed LINACs. Combining the high current advantages of storage rings and high peak brightness of LINACs will require such understanding and control of the beam dynamics that 10^-6 fraction of the beam current is taken in to account and controlled during the beam tuning. To make this possible a number of large dynamic range (LDR) (~10⁺⁶) beam diagnostics is under development and test at JLab FEL. Transverse and longitudinal LDR beam profile measurements can be used for LDR measurements of the phase space distribution and its evolution through the accelerator.

Slides WEYB01 [4.581 MB]

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WEPRO008

A Beam-driven Microwave Undulator for FEL

undulator, wakefield, electron, linac

1956

A. Kanareykin, C.-J. Jing, P. Schoessow
Euclid TechLabs, LLC, Solon, Ohio, USA
S. Baturin
LETI, Saint-Petersburg, Russia
A. Zholents
ANL, Argonne, Ilinois, USA

Funding: DOE SBIR
Microwave waveguides can in principle be used for undulators with periods less than 1 cm. Intensive work has been done on the recently proposed design that operates at the HE11 hybrid mode of a corrugated waveguide; successful experimental results have been reported recently [S.Tantawi Talk at POSIPOL 2012]. In this presentation we propose a beam driven design for an undulator based on an electron bunch train powering a microwave or mm waveguide. The drive bunch train propagates towards the undulating beam inside a dielectric loaded structure or corrugated waveguide generating high power RF. The “smart” waveguide design and a proper bunch spacing of the electron drive beam train provide single mode generation of the high magnitude undulating field that gives an undulator parameter in the range of K~1 for a high frequency device.*
*A. Zholents, HBEB Workshop, Puerto-Rico, 2013.

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WEPRO022

Modal Analysis of Helical Undulator Radiation In Cylindrical Waveguide

radiation, undulator, vacuum, linac

1989

T.L. Vardanyan, M. Ivanyan, V. Sahakyan, A.V. Tsakanian, G.S. Zanyan
CANDLE SRI, Yerevan, Armenia

The coherent radiation of the relativistic electron beam with helical orbit in circular waveguide is studied. The radiation field configuration is obtained using modal expansion technique. For short electron bunches the coherent part of radiation is evaluated. The coherent radiation effects on the bunch performance are analyzed.

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WEPRO031

Design and Commissioning of the FLASH2 Undulators

undulator, controls, operation, vacuum

2007

A. Schöps, O. Bilani, T. Ramm, M. Tischer, S. Tripathi, P. Vagin
DESY, Hamburg, Germany

This paper reports about aspects of design, manufacturing, and commissioning of the 12 FLASH2 variable gap undulator segments. The accuracy of gap drive and encoder systems was tested by magnetic measurements; changes in the phase error proved to be a highly sensitive probe to verify a reproducibility of 1 μm. After magnetic tuning of the IDs, the remaining gap dependence in the field integrals could be successfully compensated by corrector coils. Inconsiderate handling of components during assembling necessitated an elaborate demagnetisation process before the tuning could start.

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WEPRO032

Phase Shifters for the FLASH2 FEL

undulator, electron, operation, quadrupole

2010

M. Tischer, P. Neumann, A. Schöps, P. Vagin
DESY, Hamburg, Germany

The FLASH2 SASE undulator section consists of 12 IDs. Each of them is followed by an intersection component comprising a phase shifter and various parts for diagnostics and beam steering. The phase shifter is a compact and simple electromagnetic chicane and has to assure constructive interference of the radiation of adjacent undulators for all wavelengths. The magnetic performance, field errors and the hysteresis behavior have been investigated and were found to be within the required accuracy. The results are discussed in relation to the undulator conditions. From these data tables for steering the phase shifter current as function of undulator gap were derived and implemented in the control system.

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WEPRO039

Status of PAL-XFEL Undulator Program

undulator, controls, radiation, electron

2029

D.E. Kim, H.-S. Kang, W.W. Lee, K.-H. Park
PAL, Pohang, Kyungbuk, Republic of Korea
M.-H. Cho, I.S. Ko
POSTECH, Pohang, Kyungbuk, Republic of Korea
S. Karabekyan, J. Pflüger
XFEL. EU, Hamburg, Germany

Pohang Accelerator Laboratory (PAL) is developing 10 GeV, 0.1 nm SASE based FEL for high power, short pulse X-ray coherent photon sources named PAL-XFEL. At the first stage PAL-XFEL needs two undulator lines for photon source. PAL is developing undulator magnetic structure based on EU-XFEL design. Recently, the hard X-ray undulator changed its minimum magnetic gap to 8.3 mm from the previous 7.2 mm to alleviate the wake field impact, and to increase the allowances for the re alignment. Accordingly, the period is also changed from 24.4 mm to 26.0 mm to generate 0.1 nm at 10 GeV electron energy. In this report, the modification efforts and the progress on the prototyping of hard x-ray undulator system will be presented.

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WEPRO040

Field Measurement Facility for PAL-XFEL Undulators

undulator, controls, laser, software

2032

K.-H. Park, Y.-G. Jung, D.E. Kim, S.N. Kim, I.S. Ko, B.H. Lee, H.-G. Lee, M.S. Lee, S.B. Lee, H.S. Suh, C.W. Sung
PAL, Pohang, Kyungbuk, Republic of Korea

Pohang Accelerator Laboratory (PAL) is developing the SASE based FEL for X-ray coherent photon sources. The PAL developed the prototype undulator that was 5.0 m magnetic length. The PAL has constructed the undulator field measurement facility to confirm the field qualities of the XFEL undulators in the assembly building. The temperature stability of the measurement rooms was controlled within ±0.1°C. Two field measurement benches that included Hall probe scan, flip coil and stretched wire system were installed and evaluated their performances. The field profile of the prototype undulator was characterized and shimmed using the installed measurement system. This paper described the field measurement facility with the performance test results of the two benches.

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WEPRO048

A Concept of a Universal Superconducting Undulator

undulator, simulation, electron, storage-ring

2050

Y. Ivanyushenkov
ANL, Argonne, Ilinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
Tiny round electron beams of free-electron lasers and relatively new diffraction-limited storage rings make possible utilization of electromagnetic helical undulators based on double-helical windings. It has been understood for a while that a coaxial pair of double-helical windings can generate helical as well as planar magnetic fields*. Such a coil structure can potentially be realized with superconducting windings thus forming the concept of a universal superconducting undulator (Universal SCU). An example of a possible universal SCU for the recently suggested Advanced Photon Source multi-bend achromat storage ring is given in this paper. The results of the magnetic simulation together with initial cryogenic considerations are presented.
* D.F. Alferov, Yu.A. Bashamakov, E. G. Bessonov, Sov. J. Tech. Phys. 21(11), (1976) 1408.

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WEPRO053

All-optical Free Electron Lasers using Travelling-wave Thomson Scattering

electron, laser, undulator, scattering

2065

K. Steiniger, M.H. Bussmann, A.D. Debus, A. Irman, A. Jochmann, R.G. Pausch, U. Schramm
Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiation Physics, Dresden, Germany
T.E. Cowan
HZDR, Dresden, Germany

In Travelling-Wave Thomson Scattering (TWTS) the pulse front of a high-power, short-pulse laser is tilted and the dispersion of the pulse is controlled in such a way that electrons can interact over a long distance with a quasi-monochromatic electromagnetic wave. We present a complete three dimensional analytic time-dependent description of the TWTS field and use this description to derive an analytic FEL equation that shows that TWTS indeed provides for an all-optical FEL. We further derive conditions for optimum operation of the TWTS FEL, showing that EUV and XUV FEL sources are in reach using Petawatt lasers and conventional few-hundred MeV electron sources. Future laser-wakefield accelerators could potentially drive all-optical TWTS-FELs in the X-ray and beyond. TWTS itself is optimum to provide full flexibility in terms of the wavelength and bandwidth of the scattered radiation, allowing for application-optimized, highly-brilliant Thomson Scattering sources for a broad range of wavelengths from the EUV to the gamma ray spectral region.

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WEPRO094

Synchrotron Radiation Test Validations of European XFEL MCP-based Detectors at DORIS Beamline BW1

detector, photon, radiation, ion

2180

E. Syresin, A.Yu. Grebentsov, A.V. Shabunov, N.I. Zamiatin
JINR, Dubna, Moscow Region, Russia
R. Basta, T. Fiala, P. Hedbavny
Vakuum Praha, Prague, Czech Republic
O.I. Brovko
JINR/VBLHEP, Moscow, Russia
W. Freund, J. Grünert, H. Sinn
XFEL. EU, Hamburg, Germany
D. Novikov, M.V. Yurkov
DESY, Hamburg, Germany

Radiation detectors based onμchannel plates (MCP) are planned for installation at the European XFEL. Main purpose of these detectors is searching a signature of lasing and further fine tuning of the FEL process. Detectors operate in a wide dynamic range from the level of spontaneous emission to the saturation level (between a few nJ and 25 mJ), and in a wide wavelength range from 0.05 nm to 0.4 nm for SASE1 and SASE2, and from 0.4 nm to 4.43 nm for SASE3. The SR tests validation of the MCP-based detector applied for XFEL lines SASE1 and SASE2 were performed at the DORIS beamline BW1 at SR with photon energy of 8.5-12.4 keV. The absolute measurements of a photon pulse energy for hard X-ray radiation were performed with application of MCP and photodiode detectors. Pulse-to-pulse photon energy measurements with MCPs and silicon photo detector were done with 192 ns and 96 ns repetition intervals. The SR beam imaging measurement at X-ray irradiation was performed at test validation experiments.

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WEPME083

VELA: A New Accelerator Technology Development Platform for Industry

electron, cavity, target, experiment

2471

P.A. McIntosh, D. Angal-Kalinin, R.K. Buckley, S.R. Buckley, J.A. Clarke, P.A. Corlett, B.D. Fell, A.R. Goulden, C. Hill, F. Jackson, S.P. Jamison, J.K. Jones, L.B. Jones, A. Kalinin, L. Ma, J.W. McKenzie, K.J. Middleman, B.L. Militsyn, A.J. Moss, T.C.Q. Noakes, Y.M. Saveliev, D.J. Scott, B.J.A. Shepherd, R.J. Smith, S.L. Smith, T.T. Thakker, A.E. Wheelhouse, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
N. Bliss, G. Cox, G.P. Diakun, A. Gleeson, T.J. Jones, K. Robertson, M.D. Roper, E. Snedden
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
S.T. Boogert
Royal Holloway, University of London, Surrey, United Kingdom
N.J. Boulding
FMB Oxford, Oxford, United Kingdom
A. Lyapin
JAI, Egham, Surrey, United Kingdom
E.J. Morton
CXR Ltd, Guildford, United Kingdom

The Versatile Electron Linear Accelerator (VELA) facility will provide enabling infrastructures targeted at the development and testing of novel and compact accelerator technologies, specifically through partnership with industry and aimed at addressing applications in medicine, health, security, energy and industrial processing. The facility has now been commissioned at Daresbury Laboratory and the facility is now being actively utilised by industrial groups who are able to take advantage of the variable electron beam parameters available on VELA to either demonstrate new techniques and/or processes or otherwise develop new technologies for future commercial realisation. Examples of which to be presented include; demonstration of a new cargo scanning process, characterisation of novel, high performance beam position monitors, as well as other technology development applications.

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WEPRI044

Final Structure and Design Parameters of TARLA RF System

electron, rf-amplifier, LLRF, controls

2577

Ö. Karslı, A.A. Aksoy, C. Kaya, İ.B. Koc, E.Ç. Polat, O. Yavaş
Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey
M. Doğan
Dogus University, Istanbul, Turkey
S. Özkorucuklu
Istanbul University, Istanbul, Turkey

Funding: Work supported by Turkish Ministry of Development (Grant No: DPT2006K-120470)
Turkish Accelerator and Radiation Laboratory in Ankara (TARLA) is an oscillator mode IR-FEL facility which is under construction since 2011. ELBE licensed superconducting modules housing TESLA RF cavities have been manufacturing for one year and the first module will be delivered in 2015. He Cryogenic System has also started to be manufacturing at similar time with the accelerator structures. It will be delivered in 2014. High Power RF amplifiers are started to tender procedures and delivery time is planning as 2015. The installation of high power transmission lines have to be completed at the same time with the delivery date of HPRF amplifiers to test the cavities and amplifiers. In this study, the final structural design of high power RF transmission lines and design parameters of RF amplifiers for TARLA is discussed.
On behalf of TARLA Collaboration, www.tarla.org.tr

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THYA01

Control and Application of Beam Microbunching in High Brightness Linac-driven Free Electron Lasers

laser, impedance, electron, radiation

2789

G.V. Stupakov
SLAC, Menlo Park, California, USA

The remarkable properties of coherent radiation from free-electron lasers (FELs) are due to the current modulation in the beam with the modulation period equal to the radiation wavelength. This modulation is developed as a result of a beam instability when the beam propagates in a long FEL undulator, and requires a beam with a high-peak current, small emittance and a small energy spread. Unfortunately the same beam qualities make it a subject to a so-called microbunching instability at a much longer scale than the radiation wavelength. It is driven by the space charge and CSR impedances in the machine and develops during the beam acceleration in the linac, compression, and transport to the undulator. If not controlled, the microbunching instability influences dramatically the FEL performance and in the worst case can even ruin the lasing. In the presentation we will review the mechanism behind the microbunching instability, the suppression methods used in existing facilities as well as possible future developments and concepts.

Slides THYA01 [5.631 MB]

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THPPA01

FEL R&D Initiatives at the SLAC National Accelerator Laboratory

undulator, electron, laser, free-electron-laser

2842

A. Marinelli
SLAC, Menlo Park, California, USA

The successful lasing of the linac coherent light source in 2009, the first x-ray free-electron laser (xFEL) in the world, has opened a new era for x-ray photon science. The unprecedented intensity and coherence of the LCLS photon pulses have enabled groundbreaking experiments in a wide variety of fields ranging from coherent x-ray imaging to molecular and atomic physics. Despite the success of x-ray free-electron lasers, there is a steady push to extend and improve their capabilities fueled by the users' demands for new modes of operation and more precise photon and electron diagnostics. In my talk I will present several R&D initiatives at the SLAC National Accelerator Laboratory geared towards improving the performance and extending the capabilities of x-ray FELs. In particular I will focus on the spectral manipulation of FELs and our recent development of the multibunch and multicolor x-ray FEL modes at LCLS as well as our demonstration of the longitudinal space-charge amplifier as a broadband coherent light source at the NLCTA test accelerator.

Slides THPPA01 [10.793 MB]

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THPPA02

Gersch Budker Prize Presentation

klystron, collider, linear-collider, electron

2846

T. Shintake
OIST, Onna-son, Okinawa, Japan

SACLA: SPring-8 Angstrom Compact free-electron Laser, previously called XFEL/SPring-8, which is based on electron accelerator technology developed at SCSS project, in which C-band high gradient linear accelerator provides stable driving beams. Looking back upon 20 years R&D on C-band accelerator, I would like to give some advises to young scientists on doing research. The developed C-band accelerator is now providing 8 GeV electron beams at SACLA X-ray FEL in daily operation with the world best energy stability among these large scale machines.

Slides THPPA02 [17.649 MB]

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THPRO003

Progress of the LUNEX5 demonstator Project

electron, operation, undulator, laser

2856

M.-E. Couprie, C. Benabderrahmane, P. Berteaud, C. Bourassin-Bouchet, F. Bouvet, L. Cassinari, L. Chapuis, J. Daillant, M. Diop, M.E. El Ajjouri, C. Evain, C. Herbeaux, N. Hubert, M. Labat, P. Lebasque, A. Lestrade, A. Loulergue, P. Marchand, O. Marcouillé, J.L. Marlats, C. Miron, P. Morin, A. Nadji, F. Polack, F. Ribeiro, J.P. Ricaud, P. Roy, K. Tavakoli, M. Valléau, D. Zerbib
SOLEIL, Gif-sur-Yvette, France
S. Bielawski, E. Roussel, C. Szwaj
PhLAM/CERCLA, Villeneuve d'Ascq Cedex, France
B. Carré, D. Garzella
CEA/DSM/DRECAM/SPAM, Gif-sur-Yvette, France
X. Davoine
CEA/DAM/DIF, Arpajon, France
N. Delerue
LAL, Orsay, France
G. Devanz
CEA/DSM/IRFU, France
A. Dubois, J. Lüning
CCPMR, Paris, France
G. Lambert, R. Lehé, V. Malka, A. Rousse, C. Thaury
LOA, Palaiseau, France
C. Madec, A. Mosnier
CEA/IRFU, Gif-sur-Yvette, France

LUNEX5 (free electron Laser Using a New accelerator for the Exploitation of X-ray radiation of 5th generation) aims at investigating the production of short, intense, coherent pulses in the 40-4 nm spectral range [1]. It comprises two types of accelerators connected to a single Free Electron Laser (FEL) for advanced seeding configurations (seeding with High order Harmonic in Gas, echo). A 400 MeV superconducting Linear Accelerator, adapted for studies of advanced FEL schemes, will enable future upgrade towards high repetition rate and multi-user operation by splitting part of the macropulse to different FEL lines. A 0.4 - 1 GeV Laser Wake Field Accelerator (LWFA) [2] will also be qualified by the FEL application. After the Conceptual Design Report, R&D has been launched on different sub components. Following transport theoretical studies of longitudinal and transverse manipulation of a LWFA electron beam enabling to provide theoretical amplification, a test experiment is under preparation.

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THPRO004

Study of the CLIO FEL in the Far-infrared in a Partially Guided Mode

vacuum, cavity, undulator, simulation

2859

J.-M. Ortega, J.P. Berthet, F. Glotin, R. Prazeres
LCP/CLIO, Orsay, Cedex, France

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 unity. The main limitation comes from the diffraction of the optical beam due to the finite size of the vacuum chamber of the undulator. A solution is to use this chamber as a waveguide by adaptating the radius of curvature of the cavity mirrors to this regime. Then, as has been shown before* a minimum appears in the spectrum that can be produced by the FEL. We discuss the physical mechanism of this particular regime and compare it to experiments using vacuum chambers of different tranverse sizes. A good agreement is found with results of simulations and with a simple analytical formula.
* Analysis of the periodic power gaps observed in the tuning range of FELs with a partial waveguide, R. Prazeres, F. Glotin, J.-M. Ortega, Phys. Rev. STAB12, 010701 (2009)

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THPRO007

Beam-based Alignment in the European XFEL SASE1

undulator, radiation, quadrupole, simulation

2867

H. Jin, W. Decking, T. Limberg
DESY, Hamburg, Germany

The European X-ray Free Electron Laser (E-XFEL) provides an ultra-short and high-brilliant photon pulses of spatially coherent X-rays with wavelengths down to 0.05 nm by using three undulator systems. Within these undulator systems, the orbit trajectory is required to be straight to a few micron over each gain length, so that the photon beam is capable of overlapping efficiently with the electron beam. However, this requirement is not obtainable with ordinary mechanical alignment methods. For this reason, a beam-based alignment (BBA) method using BPM readings of different beam energies is applied to the E-XFEL SASE1 undulators. In this report, we describe the BBA simulation for SASE1 including alignment errors of quadrupoles and BPMs. After correction, the desired range of the orbit trajectory is attained with high confidence. In addition, to identify the reliability of an aligned orbit trajectory acquired from the BBA simulation, we present here the SASE FEL radiation simulation, in which we observe a slight decrease of radiation energy and power.

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THPRO008

Obtaining High Degree of Circular Polarization at X-ray FELs via a Reverse Undulator Taper

undulator, radiation, bunching, polarization

2870

E. Schneidmiller, M.V. Yurkov
DESY, Hamburg, Germany

Baseline design of a typical X-ray FEL undulator assumes a planar configuration which results in a linear polarization of the FEL radiation. However, many experiments at X-ray FEL user facilities would profit from using a circularly polarized radiation. As a cheap upgrade one can consider an installation of a short helical (or cross-planar) afterburner, but then one should have an efficient method to suppress powerful linearly polarized background from the main undulator. In this paper we propose a new method for such a suppression: an application of the reverse taper in the main undulator. We discover that in a certain range of the taper strength, the density modulation (bunching) at saturation is practically the same as in the case of non-tapered undulator while the power of linearly polarized radiation is suppressed by orders of magnitude. Then strongly modulated electron beam radiates at full power in the afterburner. Considering SASE3 undulator of the European XFEL as a practical example, we demonstrate that soft X-ray radiation pulses with peak power in excess of 100 GW and an ultimately high degree of circular polarization can be produced.
Phys. Rev. ST-AB 16(2013)110702

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THPRO009

Harmonic Lasing in X-ray FELs

undulator, electron, photon, operation

2873

E. Schneidmiller, M.V. Yurkov
DESY, Hamburg, Germany

Contrary to nonlinear harmonic generation, harmonic lasing in a high-gain FEL can provide much more intense, stable, and narrow-band FEL beam which is easier to handle if the fundamental is suppressed. We perform a parametrization of the solution of eigenvalue equation for lasing at odd harmonics, and present explicit expression for FEL gain length, taking into account all essential effects. We propose and discuss methods for suppression of the fundamental. We also suggest a combined use of harmonic lasing and lasing at the retuned fundamental wavelength in order to reduce bandwidth and to increase brilliance of X-ray beam. We discover that in a part of the parameter space, corresponding to the operating range of soft X-ray beamlines of X-ray FEL facilities, harmonics can grow faster than the fundamental. We suggest that harmonic lasing can be widely used in the existing or planned X-ray FEL facilities. LCLS after a minor modification can lase at the 3rd harmonic up to the photon energy of 25-30 keV providing multi-gigawatt power level. At the European XFEL the harmonic lasing would allow to extend operating range up to 100 keV, to reduce bandwidth and increase brilliance.

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THPRO010

Analysis of Operation of Harmonic Lasing Self-seeded FEL

undulator, simulation, radiation, electron

2876

E. Schneidmiller, M.V. Yurkov
DESY, Hamburg, Germany

Harmonic lasing self-seeded FEL holds great potential for significant improvement of the the longitudinal coherence of the radiation. A gap-tunable undulator is divided into two parts by setting two different undulator parameters such that the first part is tuned to a sub-harmonic of the second part. Harmonic lasing occurs in the exponential gain regime in the first part of the undulator, also the fundamental stays well below saturation. In the second part of the undulator the fundamental mode is resonant to the wavelength, previously amplified as the harmonic. The amplification process proceeds in the fundamental mode up to saturation. In this case the bandwidth is defined by the harmonic lasing (i.e. it is reduced by a significant factor depending on harmonic number) but the saturation power is still as high as in the reference case of lasing at the fundamental in the whole undulator, i.e. the spectral brightness increases. Application of the undulator tapering in the deep nonlinear regime would allow to generate higher peak powers approaching TW level. The scheme is illustrated with the parameters of the European XFEL.

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THPRO011

Investigation of the Coherence Properties of the Radiation at FLASH

radiation, emittance, electron, undulator

2879

E. Schneidmiller, M.V. Yurkov
DESY, Hamburg, Germany

We present the results of the studies of coherence properties of the radiation from FLASH for fundamental harmonic and higher odd harmonics. General overview of the parameter space is performed including peak current, emittance, and external focusing. The results of our studies show that present configuration of FLASH free electron laser is not optimal for providing ultimate quality of the output radiation. We find that the physical origin of the problem is mode degeneration. The way for improving quality of the radiation is proposed.

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THPRO013

FERMI Status Report

laser, electron, linac, experiment

2885

M. Svandrlik, E. Allaria, F. Bencivenga, C. Callegari, F. Capotondi, D. Castronovo, P. Cinquegrana, M. Coreno, R. Cucini, I. Cudin, G. D'Auria, M.B. Danailov, R. De Monte, G. De Ninno, P. Delgiusto, A.A. Demidovich, S. Di Mitri, B. Diviacco, A. Fabris, R. Fabris, W.M. Fawley, M. Ferianis, E. Ferrari, P. Finetti, L. Fröhlich, P. Furlan Radivo, G. Gaio, D. Gauthier, F. Gelmetti, L. Giannessi, M. Kiskinova, S. Krecic, M. Lonza, N. Mahne, C. Masciovecchio, M. Milloch, F. Parmigiani, G. Penco, L. Pivetta, O. Plekan, M. Predonzani, E. Principi, L. Raimondi, P. Rebernik Ribič, F. Rossi, L. Rumiz, C. Scafuri, C. Serpico, P. Sigalotti, C. Spezzani, C. Svetina, M. Trovò, A. Vascotto, M. Veronese, R. Visintini, D. Zangrando, M. Zangrando
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

FERMI, the seeded Free Electron Laser (FEL) located at the Elettra laboratory in Trieste, Italy, consists of two FEL lines. The FEL-1 facility, covering the wavelength range between 20 and 100 nm, was officially opened to external users. The shorter wavelength range, between 20 and 4 nm, is covered by the FEL-2 line, a double stage cascade operating in the “fresh bunch injection” mode, which is still under commissioning. We will report on the different FEL-1 operation modes that can be offered for users and assess the performance of the facility. The progress in the commissioning of FEL-2 will then be addressed, in particular reporting the performance attained at the lower wavelength limit; this aspect is of great interest for the user’s community of the FERMI seeded FEL since it allows to carry out experiments below the carbon K-edge.

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THPRO016

Stable Generation of High Power Self-seeded XFEL at SACLA

radiation, electron, undulator, photon

2888

T. Inagaki, N. Adumi, T. Fukui, T. Hara, Y. Inubushi, T. Ishikawa, H. Kimura, R. Kinjo, H. Maesaka, Y. Otake, H. Tanaka, T. Tanaka, K. Togawa, M. Yabashi
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
S. Goto, T.K. Kameshima, T. Ohata, K. Tono
JASRI/SPring-8, Hyogo, Japan
T. Hasegawa, S. Tanaka
SES, Hyogo-pref., Japan
A. Miura, H. Ohashi, H. Yamazaki
Japan Synchrotron Radiation Research Institute (JASRI/SPring-8), Hyogo, Japan

A self-seeded XFEL system using a transmitted beam under Bragg diffraction has been developed at the first compact XFEL facility SACLA in order to generate a brilliant single-mode XFEL with high temporal coherence. High stability and unique beam characteristics of SACLA should significantly contribute to achieve reliable, high-quality seeded XFEL operation. In particular, the short-pulse property that has been achieved in routine operation enables us to switch SASE and seeded mode quickly, without changing the electron beam parameters. This is also useful for delivering different modes to multiple beamlines simultaneously. In the test experiments carried out in autumn 2013, spectral narrowing was observed at 10 keV using diamond 400 reflection. Systematic optimization on beam properties is now in progress towards experimental use of seeded XFELs in summer 2014. This talk gives the overview of the plan, achieved results and ongoing R&D.

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THPRO017

Comparison of the Detection Performance of Three Nonlinear Crystals for the Electro-optic Sampling of a FEL-THz Source

laser, detector, lattice, damping

2891

B. Wu, L. Cao, Q. Fu, P. Tan, Y.Q. Xiong
HUST, Wuhan, People's Republic of China

The detector of a FEL-THz source at HUST is now in the physical design stage. The electro-optic (EO) sampling method will be employed for the coherent detection. The performances of three widely used EO crystals will be evaluated and compared numerically in the time domain detection: zinc telluride (ZnTe), gallium arsenide (GaAs) and gallium phosphide (GaP). The phase matching properties are analyzed to find the appropriate probe wavelength. The EO detection response is calculated to select the suitable crystal thickness and to discuss the detection ability of each crystal.

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THPRO018

Electron-Magnetic-Phase Mixing in a Linac-driven FEL to Suppress Microbunching in the Optical Regime and Below

linac, electron, laser, radiation

2894

S. Di Mitri, S. Spampinati
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
H.-S. Kang
PAL, Pohang, Kyungbuk, Republic of Korea
S. Spampinati
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Control of microbunching instability is a fundamental requirement in modern high brightness electron linacs, in order to prevent malfunction of beam optical diagnostics and contamination in the generation of coherent radiation, such as free electron lasers. We present experimental control and suppression of microbunching instability-induced optical transition radiation by means of particles’ longitudinal phase mixing in a magnetic chicane*. In presence of phase mixing, the intensity of the beam-emitted coherent optical transition radiation is reduced by one order of magnitude and brought to the same level provided, alternatively, by beam heating. The experimental results are in agreement with particle tracking and analytical evaluations of the instability gain. A discussion of applications of magnetic phase mixing to the generation of quasi-cold high-brightness ultra-relativistic electron beams is finally given.
* S. Di Mitri and S. Spampinati, Phys. Rev. Lett. 112, 134802 (2014)

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THPRO020

Linac Lattice Optimization for PAL-XFEL Hard X-ray FEL Line

linac, lattice, simulation, emittance

2900

H. Yang, J.H. Han, H.-S. Kang, I.S. Ko
PAL, Pohang, Kyungbuk, Republic of Korea

Funding: This work is supported by MSIP, Korea.
PAL-XFEL is designed to generate 1 – 0.06-nm FEL in hard x-ray FEL line. The linac for hard x-ray generates 10-GeV, 200-pC, and 3-kA electron beam. It consists of accelerating columns, three bunch compressors, an X-band linearizer, and dog-leg line. We conduct ELEGANT simulations to obtain the optimized lattice for hard x-ray line. The candidates of the optimized lattice are obtained by Multi-Objective Genetic Algorithm (MOGA) whose objectives are the FEL saturation power and length. These are evaluated with their error tolerances. Error tolerances are obtained by two methods of error simulations. First, the linear interpolation method is conducted in order to determine the machine tolerance. Also, we find out the dominant machine parameters to increase the beam jitter by this method. Second, the error simulations with random errors of machine parameters are conducted to verify the results of the linear interpolation method and calculate beam jittering levels. In this paper, we present the details of the optimized linac lattice for hard x-ray FEL. Also, we present the procedure of the linac lattice optimization.

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THPRO022

JINR Powerful Laser Driver Applied for FEL Photoinjector

laser, radiation, electron, ion

2906

E. Syresin, N. Balalykin, M.A. Nozdrin, G. Shirkov, G.V. Trubnikov
JINR, Dubna, Moscow Region, Russia
E. Gacheva, E. Khazanov, G. Luchinin, S. Mironov, A. Poteomkin, V. Zelenogorsky
IAP/RAS, Nizhny Novgorod, Russia

Funding: The work is funded by the German Federal Ministry of education and Research, project 05K10CHE.
The JINR develops a project of superconducting linear accelerator complex, based on a superconducting linear accelerator, for applications in nanoindustry, mainly for extreme ultraviolet lithography at a wavelength of 13.5 nm using kW-scale Free Electron Laser (FEL) light source. The application of kW-scale FEL source permits realizing EUV lithography with 22 nm, 16 nm resolutions and beyond. JINR-IAP collaboration constructed powerful laser driver applied for photoinjector of FEL linear accelerator which can be used for EUV lithography. To provide FEL kW-scale EUV radiation the photoinjector laser driver should provide a high macropulse repetition rate of 10 Hz, a long macropulse time duration of 0.8 ms and 8000 pulses per macropulse. The laser driver operates at wavelength of 260-266 nm on forth harmonic in the mode locking on base of Nd ions or Yb ions The laser driver micropulse energy of 1.6 uJ should provide formation of electron beam in FEL photoinjector with the bunch charge about 1 nC.

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THPRO023

Methods for the Optimization of a Tapered Free-Electron Laser

wiggler, radiation, electron, simulation

2909

A.W.L. Mak, F. Curbis, S. Werin
MAX-lab, Lund, Sweden

In a free-electron laser (FEL), the technique of wiggler tapering enables the sustained growth of radiation power beyond the initial saturation. With the goal to develop an X-ray FEL in the terawatt power regime, it is important to utilize this technique and optimize the taper profile, giving the wiggler parameter as a function of the distance along the wiggler line. This work examines two methods of optimization, which are based on the theoretical analysis by Kroll, Morton and Rosenbluth (KMR). Using the numerical simulation code GENESIS, the methods are applied to a case for the possible future FEL at the MAX IV Laboratory in Lund, Sweden, as well as a case for the LCLS-II.

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THPRO025

Conceptual Design of a X-FEL Facility using CLIC X-band Accelerating Structure

linac, klystron, simulation, gun

2914

A.A. Aksoy, O. Yavaş
Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey
D. Angal-Kalinin, J.A. Clarke
Cockcroft Institute, Warrington, Cheshire, United Kingdom
M.J. Boland
SLSA, Clayton, Australia
G. D'Auria, S. Di Mitri, C. Serpico
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
M. Doğan
Dogus University, Istanbul, Turkey
T.J.C. Ekelöf, R.J.M.Y. Ruber, V.G. Ziemann
Uppsala University, Uppsala, Sweden
W. Fang, Q. Gu
SINAP, Shanghai, People's Republic of China
A. Latina, D. Schulte, S. Stapnes, I. Syratchev, W. Wuensch
CERN, Geneva, Switzerland
Z. Nergiz
Nigde University, Nigde University Science & Art Faculty, Nigde, Turkey

Within last decade a linear accelerating structure with an average loaded gradient of 100 MV/m at 12 GHz has been demonstrated in the CLIC study. Recently, it has been proposed to use the CLIC structure to drive an FEL linac. In contrast to CLIC the linac would be powered by klystrons not by a drive beam. The main advantage of this proposal is achieving the required energies in a very short distance, thus the facility would be rather compact. In this study, we present the conceptual design parameters of a facility which could generate laser photon pulses covering the range of 1-75 Angstrom. Shorter wavelengths could also be reached with slightly increasing the energy.

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THPRO026

Design Parameters and Current Status of the TARLA Project

electron, undulator, linac, radiation

2918

A.A. Aksoy, Ö. Karslı, C. Kaya, E. Kazancı, O. Yavaş
Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey
P. Arıkan
Gazi University, Faculty of Arts and Sciences, Teknikokullar, Ankara, Turkey
S. Özkorucuklu
Istanbul University, Istanbul, Turkey

Funding: Work is supported by Ministry of Development of Turkey with Grand No: DPT2006K-120470
The Turkish Accelerator and Radiation Laboratory in Ankara (TARLA) will operate two InfraRed Free Electron Lasers (IR-FEL) covering the range of 3-250 microns. The facility will consist of an injector fed by a thermionic triode gun with two-stage RF bunch compression, two superconducting accelerating ELBE modules operating at continuous wave (CW) mode and two independent optical resonator systems with different undulator period lengths. The electron beam will also be used to generate Bremsstrahlung radiation. In this paper, we discuss design goals of the project and present status and road map of the project.
On behalf of TARLA Team

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THPRO027

Turkish Accelerator Center: The Status and Roadmap

electron, linac, proton, factory

2921

A.A. Aksoy, O. Yavaş, H.D. Duran Yıldız
Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey
B. Akkus, S. Özkorucuklu, L.S. Yalcin
Istanbul University, Istanbul, Turkey
H. Aksakal, Z. Nergiz
Nigde University, Nigde University Science & Art Faculty, Nigde, Turkey
E. Algin
Eskisehir Osmangazi University, Eskisehir, Turkey
O. Cakir
Ankara University, Faculty of Sciences, Ankara, Turkey

Funding: Ankara University
Turkish Accelerator Center (TAC) Project has started with support of the Ministry of Development (MD) of Turkey under the coordination of Ankara University. TAC is an inter-university collaboration with 12 Turkish Universities. An IR FEL facility (TARLA) based on Sc linac with 15-40 MeV energy under construction in Ankara as the first facility of TAC. It is expected that the TARLA facility will be commissioning in 2017. In addition to the TARLA, it is planned that Turkish Accelerator Center will include a third generation synchrotron radiation facility based on 1-3 GeV electron synchrotron (TAC SR), a fourth generation SASE FEL facility based on up to 5 GeV electron linac (TAC SASE FEL), a multi-purpose proton accelerator facility with 3 MeV-2 GeV beam energy (TAC PAF) and an electron-positron collider as a super charm factory (TAC PF). Construction phase of the proposed GeV scale accelerator facilities will cover next decade. In this presentation, main goals and road map of Turkish Accelerator Center will be explained. (http://thm.ankara.edu.tr)
*On behalf of TAC collaboration

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THPRO030

Developments in CLARA Accelerator Design and Simulations

wakefield, simulation, electron, undulator

2930

S. Spampinati
Cockcroft Institute, Warrington, Cheshire, United Kingdom
D. Angal-Kalinin, A.D. Brynes, D.J. Dunning, J.K. Jones, K.B. Marinov, J.W. McKenzie, B.L. Militsyn, N. Thompson, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
I.P.S. Martin
DLS, Oxfordshire, United Kingdom

We present recent developments in the accelerator design of CLARA (Compact Linear Accelerator for Research and Applications), the proposed UK FEL test facility at Daresbury Laboratory. Updates on the electron beam simulations and code comparisons including wakefields are described. Simulations of the effects of geometric wakefields in the small-aperture FEL undulator are shown, as well as further simulations on potential FEL experiments using chirped beams. We also present the results of simulations on post-FEL diagnostics.

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THPRO031

Short Pulses THz FEL for the Oxford Accelerator Science Laboratory

radiation, cavity, gun, undulator

2934

T. Chanwattana, R. Bartolini, A. Seryi
JAI, Oxford, United Kingdom
R. Bartolini
DLS, Oxfordshire, United Kingdom
E. Tsesmelis
CERN, Geneva, Switzerland

The Accelerator Science Laboratory (ASL) is under development at the John Adams Institute in Oxford with the aim of fostering advanced accelerator concepts and applications. The option to install a short pulse THz FEL based on a conventional RF accelerator driven by a RF photocathode gun is being investigated. This report presents the concept of the facility, the accelerator physics and FEL studies and engineering integration in the University physics department.

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THPRO032

Studies on LPWA-based Light Sources driven by a Transverse Gradient Undulator

undulator, laser, electron, simulation

2937

T. Chanwattana, R. Bartolini, A. Seryi
JAI, Oxford, United Kingdom
R. Bartolini
DLS, Oxfordshire, United Kingdom

The Accelerator Science Laboratory (ASL) is under development at the John Adams Institute in Oxford with the aim of fostering advanced accelerator concepts and applications. The option to install a LPWA based light source driven by a transverse gradient undulator is being investigated. This report presents the accelerator physics, FEL studies and the performance expected from such a facility.

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THPRO035

Improving and Maintaining FEL Beam Stability of the LCLS

feedback, timing, high-voltage, undulator

2943

F.-J. Decker, A.L. Benwell, W.S. Colocho, Z. Huang, A. Krasnykh, J.R. Lewandowski, T.J. Maxwell, J. Sheppard, J.L. Turner
SLAC, Menlo Park, California, USA

Funding: *Work supported by U.S. Department of Energy, Contract DE-AC02-76SF00515.
The beam stability of the Linac Coherent Light Source (LCLS) has seen many improvements over the years and has matured to a state where progress is slow and maintaining the best stability is becoming the main challenge. Single sources which are identified by various means contribute to only about 10 to 20% of the whole jitter power, meaning that their elimination gives only a small improvement of 5 to 10%. New sources need to be identified fast. Especially slow variations of a few seconds to minutes time scale are often hidden and partially corrected by feedback systems. A few episodes of increased jitter have shown the limitations of some of the feedback systems. Stability for all dimensions, transverse, longitudinal, and intensity are presented.

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THPRO038

Energy-Silenced HGHG

laser, bunching, electron, space-charge

2946

E. Hemsing, G. Marcus, A. Marinelli
SLAC, Menlo Park, California, USA
D. Xiang
Shanghai Jiao Tong University, Shanghai, People's Republic of China

We study the effect of longitudinal space charge on the correlated energy spread of a relativistic beam that has been microbunched for the emission of high harmonic radiation. We show that, in the case of microbunching induced by a laser modulator followed by a dispersive chicane, longitudinal space charge forces can act to significantly reduce the induced energy spread of the beam without a reduction in the harmonic bunching content. This effect may significantly relax constraints on the harmonic number achievable in HGHG FELs, which are otherwise limited by the induced energy spread from the laser.

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THPRO039

Model-independent Description of Shot-noise, Amplification and Saturation

bunching, electron, undulator, simulation

2949

Y.C. Jing, V. Litvinenko, G. Wang
BNL, Upton, Long Island, New York, USA
V. Litvinenko
Stony Brook University, Stony Brook, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
High-gain FEL is one of many electron-beam instabilities, which have a number of common features linking the shot noise, the amplification and the saturation. In this paper we present a new, model-independent description of the interplay between these effects and derivation of a simple formula determining the saturation and maximum attainable gain in such instabilities. Application of this model-independent formula to FEL is compared with FEL theory and simulations. We describe limitations resulting from these finding for FEL amplifiers used for seeded FELs and for Coherent electron Cooling.

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THPRO044

Report on Gun Conditioning Activities at PITZ in 2013

gun, cathode, cavity, vacuum

2962

M. Otevřel, P. Boonpornprasert, J.D. Good, M. Groß, I.I. Isaev, D.K. Kalantaryan, M. Khojoyan, G. Kourkafas, M. Krasilnikov, D. Malyutin, D. Melkumyan, T. Rublack, F. Stephan, G. Vashchenko
DESY Zeuthen, Zeuthen, Germany
G. Asova
INRNE, Sofia, Bulgaria
P. Boonpornprasert, S. Rimjaem
Chiang Mai University, Chiang Mai, Thailand
F. Brinker, K. Flöttmann, S. Lederer, B. Marchetti, S. Schreiber
DESY, Hamburg, Germany
Ye. Ivanisenko
PSI, Villigen PSI, Switzerland
M.A. Nozdrin
JINR, Dubna, Moscow Region, Russia
G. Pathak
Uni HH, Hamburg, Germany
D. Richter
BESSY GmbH, Berlin, Germany

Recently three RF guns were prepared at the Photo Injector Test Facility at DESY, location Zeuthen (PITZ) for their subsequent operation at FLASH and the European XFEL. The gun 3.1 is a previous cavity design and is currently installed and operated at FLASH, the other two guns 4.3 and 4.4 were of the current cavity design and are dedicated to serve for the start-up of the European XFEL photo-injector. All three cavities had been dry-ice-cleaned prior their conditioning and hence showed low dark current levels. The lowest dark current level – as low as 60μA at 65MV/m field amplitude – has been observed for the gun 3.1. This paper reports in details about the conditioning process of the most recent gun 4.4. It informs about experience gained at PITZ during establishing of the RF conditioning procedure and provides a comparison with the other gun cavities in terms of the dark currents. It also summarizes the major setup upgrades, which have affected the conditioning processes of the cavities.

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THPRO050

Study of a THz/VUV Free Electron Laser Facility in Taiwan

laser, radiation, undulator, linac

2980

N.Y. Huang, M.C. Chou, C.-S. Hwang, W.K. Lau, A.P. Lee
NSRRC, Hsinchu, Taiwan
A. Chao, J. Wu
SLAC, Menlo Park, California, USA
C.H. Chen, Y.-C. Huang
NTHU, Hsinchu, Taiwan
X.M. Yang
DICP, Dalian, People's Republic of China

A free electron laser (FEL) facility aimed for VUV and THz radiation is being studied at National Synchrotron Radiation Research Center (NSRRC) in Taiwan. Strong consideration has been given to minimize the cost by making maximum use of existing hardware at NSRRC. One unique consideration is to use an existing undulator for the dual functions of the THz radiator and the modulator of a HGHG section. Design emphasizes versatility of operation and beam quality control and compensation of nonlinearities, with a vision that it will allow as much as possible future upgrades as well as later R&D of FEL physics. The polarization control of the THz radiation provides novel application for the users. The facility is to be housed in the existing 38-m by 5-m tunnel of the TPS Linac Test Laboratory.

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THPRO051

Cavity Design for a S-Band Photoinjector RF Gun with 400 Hz Repetition Rate

cavity, gun, cathode, emittance

2983

J.W. McKenzie, L.S. Cowie, P. Goudket, B.L. Militsyn
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
T.J. Jones
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
V.V. Paramonov
RAS/INR, Moscow, Russia

As part of the design of CLARA (Compact Linear Accelerator for Research and Applications), the proposed UK FEL test facility at Daresbury Laboratory, a high repetition rate S-band photoinjector RF gun is being developed. This gun will be able to operate at up to 400 Hz repetition rate in single bunch mode. We present the initial cavity design including its optimisation for the beam dynamics of CLARA. We also present the initial cooling design for the cavity which will enable the high repetition rates to be achieved.

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THPRO074

Characterization of the Longitudinal Wakefields in the MAX IV Linac

linac, wakefield, simulation, gun

3050

O. Karlberg, F. Curbis, S. Thorin, S. Werin
MAX-lab, Lund, Sweden

In the second part of 2014, the 3GeV linac at the MAX IV laboratory will enter its commissioning stage. Equipped with two guns, the linac will act as a full energy injector for the two storage rings and at the same time provide high brightness pulses to a Short Pulse Facility (SPF). Compression in the linac is done in two double achromats with fixed R56 that relies upon the RF phase introduced energy chirp, which in this case is strongly enhanced by the longitudinal wakefields. Since the longitudinal wakefields plays a major role in the compression and bunch shaping they need to be carefully investigated during the commissioning. In this proceeding we will discuss a measurement technique that will be used during commissioning to characterize the longitudinal wakefields and their precise effects on e.g. the bunch shape and the energy spread. Predictions obtained from particle tracking will be presented.

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THPRO077

The New FREIA Laboratory for Accelerator Development

cryomodule, controls, linac, cryogenics

3059

R.J.M.Y. Ruber, A.K. Bhattacharyya, T.J.C. Ekelöf, K. Fransson, K.J. Gajewski, V.A. Goryashko, L. Hermansson, M. Jacewicz, T. Lofnes, M. Olvegård, R. Santiago Kern, R. Wedberg, R.A. Yogi, V.G. Ziemann
Uppsala University, Uppsala, Sweden
D.S. Dancila, A. Rydberg
Uppsala University, Department of Engineering Sciences, Uppsala, Sweden

The FREIA laboratory is a Facility for REsearch Instrumentation and Accelerator Development at Uppsala University, Sweden constructed recently to develop and test accelerator components. Initially it will develop the RF system for the spoke cavities of the ESS linac and test prototype spoke cavities at nominal RF power. For this purpose we installed a helium liquefaction plant, a versatile horizontal test cryostat and two 352 MHz RF power stations, one based on two tetrodes and the other on solid state technology. Beyond these developments FREIA will house a neutron generator and plans for a THz FEL are under discussion. FREIA is embedded in the Ångström physics, chemistry and engineering campus at Uppsala in close proximity to mechanical workshops, clean room with electron microscopes, tandem accelerator and the biomedical center.

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THPME081

Plans for an Australian XFEL Using a CLIC X-band Linac

storage-ring, synchrotron, linac, emittance

3424

M.J. Boland, T.K. Charles, R.T. Dowd, G. LeBlanc, Y.E. Tan, K.P. Wootton, D. Zhu
SLSA, Clayton, Australia
R. Corsini, A. Grudiev, A. Latina, D. Schulte, S. Stapnes, I. Syratchev, W. Wuensch
CERN, Geneva, Switzerland

Preliminary plans are presented for a sub-Angstrom wavelength XFEL at the Australian Synchrotron light source site. The design is based around a 6 GeV x-band linac from the CLIC Project. One of the motivations for the design is to have an XFEL co-located on the site with existing storage ring based synchrotron light source. The desire and ability of the Australian photon science community to win beamtime on existing XFELs has lead to this design study to plan for a future machine in Australia. The technology choice is also driven by the Australian participation in the CLIC Collaboration and the local HEP community.

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THPME109

EOS at CW Beam Operation at ELBE

electron, laser, operation, diagnostics

3492

Ch. Schneider, M. Gensch, M. Kuntzsch, P. Michel, W. Seidel
HZDR, Dresden, Germany
P.E. Evtushenko
JLab, Newport News, Virginia, USA
Ç. Kaya
Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey
A. Shemmary, N. Stojanovic
DESY, Hamburg, Germany

The ELBE accelerator is a super conduction electron cw machine located at the Helmholtz Center Dresden Rossendorf Germany with 1 mA current, now tested for up to 2 mA. Besides other important diagnostics for setting up the machine for user beam time and further improvement of the machine – a THz source is momentary under commissioning – a EOS measuring station for bunch length measurements is locate right behind the second super conducting Linac. Measuring with a crystal in the vicinity of an up to 2 mA cw beam implies higher beam loss and also higher radiation exposure of the crystal and hence also a safety risk for the UHV conditions of the super conducting cavities in the case of crystal damage. Therefore the EOS measuring principle is adapted to larger measuring distances and also for beam requirements with lower bunch charge at ELBE. A description of the setup, considerations of special boundary conditions and as well results for 13 MHz cw beam operation are presented.

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THPME142

Design of the Beam Profile Monitors for THz Source Based FEL

controls, linac, target, LabView

3584

J. Liu, P. Lu, B.G. Sun, K. Tang, J.G. Wang, J. Xu, Y.L. Yang, Z.R. Zhou
USTC/NSRL, Hefei, Anhui, People's Republic of China

Design of the Beam Profile Monitors for THz Source Based FEL* J. Liu, P. Lu, B. G. Sun#, Y. J. Pei, Y. L. Yang, Z.R. Zhou, J. G. Wang, K. Tang, J. Xu NSRL, School of Nuclear Science and Technology, University of Science and Technology of China, Hefei 230029, P. R. China Abstract To meet requirements of high performance THz-FEL, a compact FEL facility was proposed. In order to characterize the beam, some beam profile monitors were designed. There are four flags for beam profiles in Linac，one pop-in monitor for high precision beam profile inside a small-gap undulator, and two screens to measure the beam energy spread and emittance of Linac. On one hand, we need to use software to control the position of these profile monitors, on the other hand, we need screens to display the results. This paper describes how to design and control these monitors, as well as how to measure the beam parameter.

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THPME156

Convergent Cherenkov Radiation from Dielectric Targets

target, radiation, optics, vacuum

3626

S.N. Galyamin, E.S. Belonogaya, A.V. Tyukhtin, V.V. Vorobev
Saint-Petersburg State University, Saint-Petersburg, Russia
E.S. Belonogaya
LETI, Saint-Petersburg, Russia

Funding: Work was supported by the Grant of the President of Russian Federation (No. 273.2013.2).
Cherenkov radiation is a convenient tool for charged particle detection and bunch diagnostics. However, due to the complexity of real radiator geometry, different approximate techniques are elaborated for investigation of excited radiation*. Here we develop recently reported** approximate method for calculating Cherenkov radiation of a charge flying near a dielectric target having two main boundaries (the first interacts with a charge field and the second mainly refracts a generated radiation). We focus on cases where the radiation outside the target is convergent and use two methods for field investigation: ray optical technique and aperture integration technique. First, we deal with the case of a conical target with a vacuum channel. Under certain conditions, this radiation is concentrated near the line being the symmetry axis of the target. Second, we find the specific shape of the target that concentrates radiation in a small vicinity of given point (focus). Such targets can be used for improvement of detectors and bunch diagnostics systems based on Cherenkov effect.
*A.P. Potylitsyn et al., Diffraction Radiation from Relativistic Particles, STMP 239 (Springer, 2010).
**E.S. Belonogaya, A.V. Tyukhtin, S.N. Galyamin, Phys. Rev. E, 87, 043201 (2013).

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THPME170

Prospects for Longitudinal Phase-space Measurements at the MAX IV Linac

linac, electron, simulation, extraction

3665

F. Curbis, O. Karlberg, S. Thorin, S. Werin
MAX-lab, Lund, Sweden

Knowing the longitudinal phase space of an electron beam is one of the most important and crucial issues in short-pulses linacs. To achieve this task expensive and rather complicated setups (like transverse deflecting cavities) are usually implemented. The MAX IV 3 GeV linac will be used to inject into two rings and to drive a short pulse facility. Nevertheless, a more deep understanding of the beam quality would be useful especially in view of an upgrade as FEL driver. Another interesting aspect is to evaluate how the double-achromat bunch compressors are performing. We are studying how to implement off-phase acceleration: last part of the linac will be set at zero-crossing phase and the transfer line to the 3 GeV ring could be used as energy spectrometer to retrieve the bunch profile. In the present configuration of the MAX IV linac this procedure will allow to check the bunch length after the first bunch compressor. Since it is work in progress, in this contribution we present a sketch of the measurement and the feasibility of the method will be explored by means of simulations.

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THPME184

Improvement of Beam Imaging Systems through Optics Propagation Simulations

simulation, radiation, optics, photon

3709

B. Bolzon, T. Lefèvre, S. Mazzoni
CERN, Geneva, Switzerland
A.S. Aryshev
KEK, Ibaraki, Japan
B. Bolzon, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
B. Bolzon, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
P. Karataev, K.O. Kruchinin
Royal Holloway, University of London, Surrey, United Kingdom
P. Karataev, K.O. Kruchinin
JAI, Egham, Surrey, United Kingdom

Optical Transition Radiation (OTR) is emitted when a charged particle crosses the interface between two media with different dielectric properties. It has become a wide-spread method for beam profile measurements. However, there are no tools to simulate the propagation of the OTR electric field through an optical system. Simulations using ZEMAX have been performed in order to quantify optical errors, such as aberrations, diffraction, depth of field and misalignment. This paper focuses on simulations of vertically polarized OTR photons with the aim of understanding what limits the resolution of realistic beam imaging systems.

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THPRI073

Achieving Higher Energies via Passively Driven X-band Structures

cavity, impedance, electron, linac

3933

T. Sipahi, S. Biedron, S.V. Milton
CSU, Fort Collins, Colorado, USA

Due to their higher intrinsic shunt impedance X-band accelerating structures significant gradients with relatively modest input powers, and this can lead to more compact particle accelerators. At the Colorado State University Accelerator Laboratory (CSUAL) we would like to adapt this technology to our 1.3 GHz L-band accelerator system using a passively driven 11.7 GHz traveling wave X-band configuration that capitalizes on the high shunt impedances achievable in X-band accelerating structures in order to increase our overall beam energy in a manner that does not require investment in an expensive, custom, high-power X-band klystron system. Here we provide the design details of the X-band structures that will allow us to achieve our goal of reaching the maximum practical net potential across the X-band accelerating structure while driven solely by the beam from the L-band system.

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