LINAC2016 - Classification: 1 Electron Accelerators and Applications / 1A Electron Linac Projects

Paper	Title	Page
MO2A01	The LCLS-II SCRF Linac
	M.C. Ross, A. Burrill SLAC, Menlo Park, California, USA
	The LCLS-II CW x-ray FEL is based on high Q0 1.3 GHz SCRF cavities powered by solid-state amplifiers. This talk will describe the R&D towards these cavities and the recent results of cryomodule prototypes.
	Slides MO2A01 [18.815 MB]
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MO2A02	Commissioning and Plans at IOTA/FAST
	D.R. Broemmelsiek, C.M. Baffes, C.I. Briegel, K. Carlson, B.E. Chase, D.J. Crawford, E. Cullerton, J.S. Diamond, N. Eddy, D.R. Edstrom, E.R. Harms, J.R. Leibfritz, A.H. Lumpkin, E. Prebys, J. Reid, J. Ruan, T. Sen, V.D. Shiltsev, G. Stancari, J.C.T. Thangaraj, R.M. Thurman-Keup, A. Valishev, A. Warner Fermilab, Batavia, Illinois, USA A. Halavanau, D. Mihalcea, P. Piot Northern Illinois University, DeKalb, Illinois, USA J. Hyun Sokendai, Ibaraki, Japan P. Kobak BYU-I, Rexburg, USA W.D. Rush KU, Lawrence, Kansas, USA
	The electron injector at IOTA/FAST is based on a 50MeV RF photoinjector and SRF 1.3 GHz cryomodule to accelerate beam up to 300 MeV. Photoinjector and Cryomodule (CM2) were commissioned separately. CM2 demonstrated world record accelerating gradient > 30MV/m in all cavities. Commissioning of the 50MeV RF photoinjector was successfully done recently. Results of commissioning, status and plans for IOTA/FAST are presented.
	Slides MO2A02 [6.248 MB]
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MO2A03	Commissioning and Early Operation of the ARIEL e-Linac	12
	T. Planche, M. Alcorta, F. Ames, R.A. Baartman, C.B. Barquest, B. Humphries, D. Kaltchev, S.R. Koscielniak, R.E. Laxdal, Y. Ma, M. Marchetto, S. Saminathan, E. Thoeng TRIUMF, Vancouver, Canada P. Jung UW/Physics, Waterloo, Ontario, Canada
	The ARIEL electron linac has been added to the TRIUMF facility as a new driver for the production of radioactive isotopes through photo-fission to complement the existing 500 MeV, H^- TRIUMF cyclotron. The electron beam driver is specified as a 50 MeV, 10 mA cw superconducting electron linac at 1.3 GHz. The first 30 MeV stage of the e-linac consisting of two cryomodules is completed. The paper will describe the recent commissioning and early operation results.
	Slides MO2A03 [25.277 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MO2A03
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MO2A04	Low Emittance and High Current Electron Linac Development at Tsinghua University	17
	C.-X. Tang, H.B. Chen, Z.J. Chi, Y.-C. Du, W.-H. Huang, J. Shi, Q.L. Tian, D. Wang, W. Wang, L.X. Yan, Z. Zhang, Z. Zhang, L.M. Zheng, Z. Zhou TUB, Beijing, People's Republic of China
	A 50MeV electron linac have been developed in Tsinghua University, which consists of a 1.6Cell photocathode rf gun, a 3-meter s-band SLAC type traveling wave (TW) accelerating structure an a s-band TW buncher. The photocathode rf gun is working at 120MV/m, 2856MHz, with very small dark current. The emittance of the electron beam is less than 1mm.mrad at 500pC, and 0.5mm.mrad at 200pC. The linac is designed for Tsinghua Thomson scattering X-ray source (TTX), and 2x10⁷ photon/bunch at 50keV has been got and some application experiments with the x-ray have been carried out. The new photocathode rf gun and x-band high gradient accelerating structure development will also be introducted in this talk.
	Slides MO2A04 [11.413 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MO2A04
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MO3A01	Status of SwissFEL	22
	F. Löhl PSI, Villigen PSI, Switzerland
	SwissFEL is a hard x-ray free-electron laser facility that is currently constructed at PSI. This paper gives an overview of the facility, describes the main sub-systems of the accelerator, and summarizes the installation and commissioning status.
	Slides MO3A01 [315.102 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MO3A01
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MOOP11	Operation of the CEBAF 100 MV Cryomodules	65
MOPLR003	use link to see paper's listing under its alternate paper code
	C. Hovater, T.L. Allison, R. Bachimanchi, G.H. Biallas, E. Daly, M.A. Drury, A. Freyberger, R.L. Geng, G.E. Lahti, R.A. Legg, C.I. Mounts, R.M. Nelson, T. E. Plawski, T. Powers JLab, Newport News, Virginia, USA
	Funding: Authored by JSA, LLC under U.S. DOE Contract DE-AC05- 06OR23177. The Continuous Electron Beam Accelerator Facility (CEBAF) 12 GeV upgrade reached its design energy in December of 2015. Since then CEBAF has been delivering 12 GeV beam to experimental Hall D and 11 GeV to experimental halls A and B in support of Nuclear physics. To meet this energy goal, ten new 100 MV cryomodules (80 cavities) and RF systems were installed in 2013. The superconducting RF cavities are designed to operate CW at a average accelerating gradient of 19.2 MV/m. To support the higher gradients and higher QL (3.2×107) operations, the RF system uses 13 kW klystrons and digital LLRF to power and control each cavity. This paper reports on the C100 operation and optimization improvements of the RF system and cryomodules.
	Slides MOOP11 [1.574 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOOP11
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MOPLR004	Development of an High Gradient, S-band, Accelerating Structure for the FERMI Linac	136
	C. Serpico, I. Cudin Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy A. Grudiev CERN, Geneva, Switzerland
	The FERMI seeded free-electron laser (FEL), located at the Elettra laboratory in Trieste, is driven by a 200 meter long, S-band linac routinely operated at nearly 1.5 GeV and 10 Hz repetition rate [1]. The high energy part of the Linac is equipped with seven, 6 meter long Backward Traveling Wave (BTW) structures: those structures have small iris radius and a nose cone geometry which allows for high gradient operation [2]. Nonetheless a possible development of high-gradient, S-band accelerating struc-tures for the replacement of the actual BTW structures is under consideration. This paper investigates a possible solution for RF couplers that could be suitable for linac driven FEL where reduced wakefields effects, high oper-ating gradient and very high reliability are required.
	Poster MOPLR004 [0.947 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR004
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MOPLR005	Design, Manufacturing and Installation of Two Dual-Feed Accelerating Structures for the FERMI Injector	139
	C. Serpico, A. Fabris, G. Penco, M. Svandrlik Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy B. Keune RI Research Instruments GmbH, Bergisch Gladbach, Germany
	FERMI is a seeded Free Electron Laser (FEL) driven by a warm S-band Linac. In the injector region, two 3- meter long Forward Traveling Wave (FTW) accelerating structures, coming from the old Elettra injector, were installed. In order to improve the e-beam quality at higher bunch charge, it was decided to replace the existing ones with two dual-feed accelerating structures. Those structures have been designed and manufactured by RI Research Instruments GmbH and delivered to Elettra in July 2015. The following paper will report about the RF design and the manufacturing of the new structures. Details about the RF conditioning and the installation will also be illustrated.
	Poster MOPLR005 [1.100 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR005
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MOPLR006	Monopole HOMs Dumping in the LCLS-II 1.3 GHz Structure	142
	A. Lunin, T.N. Khabiboulline, N. Solyak Fermilab, Batavia, Illinois, USA
	Funding: Operated by Fermi Research Alliance, LLC, under Contract DE-AC02-07CH11359 with the U.S. DOE Developing an upgrade of Linac Coherent Light Source (LCLS-II) is currently underway. The central part of LCLS-II is a continuous wave superconducting RF (CW SRF) electron linac. High order modes (HOMs) excited in SRF structures by passing beam may deteriorate beam quality and affect beam stability. In this paper we report the simulation results of monopole High Order Modes (HOM) spectrum in the 1.3 GHz accelerating structure. Optimum parameters of the HOM feedthrough are suggested for minimizing RF losses on the HOM antenna tip and for preserving an efficiency of monopole HOMs damping simultaneously.
	Poster MOPLR006 [0.647 MB]
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MOPLR007	Redesign of the End Group in the 3.9 GHz LCLS-II Cavity	145
	A. Lunin, I.V. Gonin, T.N. Khabiboulline, N. Solyak Fermilab, Batavia, Illinois, USA
	Funding: Operated by Fermi Research Alliance, LLC, under Contract DE-AC02-07CH11359 with the U.S. DOE Development and production of Linac Coherent Light Source II (LCLS-II) is underway. The central part of LCLS-II is a continuous wave superconducting RF (CW SCRF) electron linac. The 3.9 GHz third harmonic cavity similar to the XFEL design will be used in LCLS-II for linearizing the longitudinal beam profile. The initial design of the 3.9 GHz cavity developed for XFEL project has a large, 40 mm, beam pipe aperture for better higher-order mode (HOM) damping. It is resulted in dipole HOMs with frequencies nearby the operating mode, which causes difficulties with HOM coupler notch filter tuning. The CW linac operation requires an extra caution in the design of the HOM coupler in order to prevent its possible overheating. In this paper we present the modified 3.9 GHz cavity End Group for meeting the LCLS-II requirements LCLS-II 3.9 GHz Cryomodules, Physics Requirements Document, LCLSII-4.1-PR-0097-R1, SLAC, USA, 2015
	Poster MOPLR007 [1.590 MB]
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MOPLR008	Status Of the ILC Main Linac Design	149
	A. Saini, V.V. Kapin, N. Solyak Fermilab, Batavia, Illinois, USA
	International Linear collider (ILC) is a proposed accelerator facility which is primarily based on two 11-km long superconducting main linacs. In this paper we present recent updates on the main linac design and discuss changes made in order to meet specification outlined in the technical design report (TDR).
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MOPLR009	X-Band Travelling Wave Accelerating Section R&D for HTF	152
	K. Jin USTC/NSRL, Hefei, Anhui, People's Republic of China
	Hefei Light Source (HLS) was mainly composed of an 800 MeV electron storage ring and an 800MeV-1GeV constant-gradient accelerator in NSRL. The new Linac with Full Energy Injection and the Top-up Injection scheme has been developed successfully. And the other functioning as X Ray Free Electron Laser test facility has been considered. In the project, in order to compress the bunch length and to achieve the beam energy distribution linearization. A 15MeV, operation frequency 11.424GHz traveling wave accelerating section as harmonic compensation is being developed. In this paper, X Ray Free Electron Laser Hefei Test Facility (HTF) is introduce briefly. And the R&D of the x-band accelerating section with collinear load are presented in detail.
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MOPLR010	4 K SRF Operation of the 10 MeV CEBAF Photo-Injector	155
	G.V. Eremeev, M.A. Drury, J.M. Grames, R. Kazimi, M. Poelker, J.P. Preble, R. Suleiman, Y.W. Wang, M. Wright JLab, Newport News, Virginia, USA
	Funding: Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. SRF accelerating cavities are often operated in superfluid helium of temperature near 2 K to enhance the cavity quality factor Q0 and manage cryogenic heat loads, which are particularly important at large SRF accelerator facilities. This temperature paradigm, however, need not put SRF technology out of the reach of small institutions or even limit SRF operation at large facilities to provide 10-100 MeV beam energy. At the Jefferson Lab CEBAF accelerator there are regularly scheduled maintenance periods during which the liquid helium temperature is raised to 4 K, reducing cryogenic plant power consumption by ~50% and saving megawatts of electrical power. During such a recent period, we accelerated a continuous-wave electron beam at the CEBAF photo-injector to 6.3 MeV/c with current ~80μA using two niobium cavities at helium temperature of 4 K. This contribution describes the SRF and cryogenic performance and uses measured beam quality and energy stability as key metrics. These measurements indicate that 4 K operation of niobium SRF cavities in CEBAF and at small institutions may be a sensible and cost effective mode of operation, provided the cryogenic load associated with lower Q0 is manageable for the number of SRF cavities needed. For Jefferson Lab, this enhances our scientific reach allowing additional low-energy ~10 MeV experiments each year.
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MOPLR011	Design of a Dielectric-lined Waveguide for Terahertz-driven Linear Electron Acceleration	158
SPWR012	use link to see paper's listing under its alternate paper code
	A.L. Healy, G. Burt Cockcroft Institute, Lancaster University, Lancaster, United Kingdom M.J. Cliffe, D.M. Graham The University of Manchester, The Photon Science Institute, Manchester, United Kingdom S.P. Jamison STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom R. Valizadeh Cockcroft Institute, Warrington, Cheshire, United Kingdom
	A dielectric-lined waveguide has been designed for use as an accelerating structure in terahertz-driven electron acceleration experiments at Daresbury. Experimental verification of acceleration will take place on Versatile Electron Linear Accelerator (VELA). The choice of a rectangular waveguide structure with sidewall dielectric layers enables tuning by varying the spacing between dielectric slabs to account for potential manufacturing errors. Schemes for coupling free-space single cycle THz pulses into the waveguide have been evaluated and optimised through CST simulation. Comparison of simulation with experimental measurements will also be presented.
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MOPLR012	Compact Beam Position Monitor for Electron and Proton Machines	161
	M. Žnidarčič, M. Cargnelutti I-Tech, Solkan, Slovenia
	Monitoring and subsequent optimization of the linacs, transfer lines, energy recovery linacs and synchrotrons, requires specific instrumentation optimized for beam position and charge measurements. Libera Spark is the newly developed instrument intended for position and charge monitoring in electron and proton machines. The motivation, processing principles and first results at laboratories are presented.
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MOPLR013	Investigations on Electron Beam Imperfections at PITZ	165
	M. Krasilnikov, P. Boonpornprasert, J.D. Good, M. Groß, H. Huck, I.I. Isaev, D.K. Kalantaryan, O. Lishilin, G. Loisch, D. Melkumyan, A. Oppelt, G. Pathak, Y. Renier, T. Rublack, F. Stephan, G. Vashchenko, Q.T. Zhao DESY Zeuthen, Zeuthen, Germany G. Asova INRNE, Sofia, Bulgaria C. Hernandez-Garcia JLab, Newport News, Virginia, USA
	Since more than a decade, the photo injector test facility at DESY, Zeuthen site (PITZ), has developed and optimized high brightness electron sources for modern Free Electros Lasers like FLASH and the European XFEL. Despite a very high performance of the photo injector was experimentally demonstrated, several discrepancies between measurements and beam dynamics simulations have been revealed. Although the optimized measured values of the projected transverse emittance are close to those obtained from the beam dynamics simulations, the corresponding experimental machine parameters show certain systematic deviations from the simulated optimized setup. As a source for these deviations, electron beam imperfections were experimentally investigated. This includes studies on bunch charge production, electron beam imaging using the RF gun with its solenoid, and investigations on the transverse asymmetry of the electron beam generated in a rotationally symmetric gun cavity. Experimental studies were supplied with corresponding beam dynamics simulations. The paper reports on results of these studies.
	Poster MOPLR013 [2.140 MB]
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MOPLR014	Construction of a Third Recirculation for the S-DALINAC*	168
	M. Arnold, T. Kürzeder, J. Pforr, N. Pietralla, M. Steinhorst TU Darmstadt, Darmstadt, Germany F. Hug IKP, Mainz, Germany
	Funding: * Work supported by DFG through CRC 634 and RTG 2128 Since 1991 the superconducting recirculating electron accelerator S-DALINAC is running at TU Darmstadt. Its designated design energy of 130 MeV wasn't reached yet due to a lower quality factor of the 3 GHz cavities and thus a higher dissipated power to the helium bath. To increase the maximum achievable energy in cw operation from approx. 85 MeV to the design value of 130 MeV the main accelerator will be passed a fourth time. In this configuration the accelerating gradients of the cavities can be lowered, so that the resulting dissipated power will match the available cooling power of the cryo plant. To realize an additional main linac pass a new recirculation beam line is needed. The most crucial points are the design of the separation dipole and its mirrored version as well as a properly calculated lattice. For the implementation of a new recirculation beam line the existing sections must be adapted to fit the new boundary conditions. This contribution will present some aspects of the design and will report on the actual status of this project.
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MOPLR015	Thermal-Mechanical Study of 3.9 GHz CW Coupler and Cavity for LCLS-II Project	171
	I.V. Gonin, E.R. Harms, T.N. Khabiboulline, N. Solyak, V.P. Yakovlev Fermilab, Batavia, Illinois, USA
	Third harmonic system was originally developed by Fermilab for FLASH facility at DESY and then was adopted and modified by INFN for the XFEL project [1-3]. In contrast to XFEL project, all cryomodules in LCLS-II project will operate in CW regime with higher RF average power for 1.3 GHz and 3.9 GHz cavities and couplers. Design of the cavity and fundamental power coupler has been modified to satisfy LCLS-II requirements. In this paper we discuss the results of COMSOL thermal and mechanical analysis of the 3.9 GHz coupler and cavity to verify proposed modifica-tion of the design. For the dressed cavity we present simulations of Lorentz force detuning, helium pressure sensitivity df/dP and major mechanical resonances.
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MOPLR016	Status of the Injection System of the CLARA FEL Test Facility	174
	B.L. Militsyn, D. Angal-Kalinin, R.K. Buckley, R.J. Cash, J.A. Clarke, L.S. Cowie, B.D. Fell, P. Goudket, T.J. Jones, K.B. Marinov, P.A. McIntosh, J.W. McKenzie, K.J. Middleman, T.C.Q. Noakes, B.J.A. Shepherd, R. Valizadeh, A.E. Wheelhouse STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom G. Burt Cockcroft Institute, Lancaster University, Lancaster, United Kingdom V.V. Paramonov RAS/INR, Moscow, Russia
	The 250 MeV CLARA FEL test facility is now under construction at Daresbury Laboratory. Electron beam for this facility is provided by two normal conducting S-band photocathode guns: a 10 Hz 2.5 cell gun earlier used as the injector for the VELA machine, and a 400 Hz 1.5 cell gun now under commissioning. At the initial stage of Phase I CLARA will operate with the 10 Hz gun and a 45 MeV 2 m long linac section working as a buncher and/or booster. The beam will be deflected into the existing VELA beamline with an S-bend and directed to the spectrometer line for analysing beam properties or into one of two VELA user areas. The 400 Hz gun will be installed in the VELA beamline for detailed high power RF and beam commissioning in the VELA beam diagnostics suite. As the 400 Hz gun is equipped with an interchangeable photocathode it is possible to investigate different metal photocathodes and select the one providing minimal beam emittance at highest quantum efficiency. A state of the art photocathode preparation system is under commissioning at Daresbury. After commissioning the 400 Hz gun will be installed to the CLARA beam line to deliver high energy, high repetition rate beams for the FEL facility, and the 10 Hz gun will be returned to the VELA beam line.
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MOPLR018	Upgrade of the Klystron Modulator of the L-Band Electron Linac at Osaka University for Higher Stability	178
	K. Furukawa, G. Isoyama ISIR, Osaka, Japan R. Kato KEK, Ibaraki, Japan K. Kawase HSRC, Higashi-Hiroshima, Japan A. Tokuchi Pulsed Power Japan Laboratory Ltd., Kusatsu-shi Shiga, Japan
	The klystron modulator for the L-band linac is upgraded for higher stability. The two-step charging system for the pulse forming network (PFN) is upgraded by adding a high impedance resonant charging line in parallel with the main line. The charging step of the PFN voltage is reduced considerably near the setting value by switching the main resonance line off so that the charging current flows only through the high impedance line. The second model of the solid-state switch is developed using 60 static-induction thyristors, ten of which are connected in series with six such series connected in parallel to meet maximum specifications of 25 kV and 6 kA. The air-cooling capacity is reinforced so that repetition rate is increased from 10 pps for the first model to 60 pps. The fluctuation and accuracy of the klystron voltage are measured to be 7.8×10^-6 or 7.8 ppm for the upgraded klystron modulator using a differential amplifier with much higher sensitivity than one used in the previous measurement.
	Poster MOPLR018 [0.840 MB]
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MOPLR020	Challenges in Realizing the LCLS-II Cryomodule Production	181
	A. Burrill SLAC, Menlo Park, California, USA
	The LCLS-II project requires the assembly and installation of 37 cryomodules in order to deliver a 4 GeV electron beam to the undulators to produce both soft and hard x-rays at a repetition rate up to 1 MHz. All of the cryomodules will operate in continuous wave mode, with 35 operating at 1.3 GHz for acceleration and 2 operating at 3.9 GHz to linearize the longitudinal beam profile. One of the challenges of this project, and the topic of this paper, is coordinating the effort of three DOE labs in order to realize this machine in just a few years time. This coordination is necessary due to the fact that the cryomodules will be assembled at both Jefferson Lab and Fermi Lab, tested, and then shipped to SLAC for installation, commissioning and operation. This paper will report on our experiences to date, issues that have been identified and planned mitigation going forward.
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MOP106015	Commissioning Status of the Chopper System for the MAX IV Injector	316
	D. Olsson, J. Andersson, F. Curbis, L. Isaksson, L. Malmgren, E. Mansten, S. Thorin MAX IV Laboratory, Lund University, Lund, Sweden
	The MAX IV facility in Lund, Sweden consists of two storage rings for production of synchrotron radiation. The two rings are designed for 1.5 GeV and 3 GeV, respectively, where the former is under construction, and the latter is undergoing beam commissioning. Both rings will be operating with top-up injections delivered by a full-energy injector that consists of 39 traveling-wave S-band LINAC structures. In order to reduce losses of high-energy electrons along the injector and in the rings during injection, only electrons that are within an allowed time structure are accelerated. This time structure depends on several parameters such as the available RF voltage and the radiation losses in the ring that is about to be injected, but also on the momentum acceptance of the transport lines in the injector. The electrons that are outside the allowed time structure are dumped when they have energies below 3 MeV by a chopper system that is located between a thermionic RF gun and the first LINAC structure. Basically, the chopper system consists of two planar striplines and a variable aperture, and the first stripline is fed with a superposed RF signal and the second one with HV pulses. The performance of the chopper system during commissioning of the 3 GeV ring is presented in this article.
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MOP106016	High Power RF Requirements for Driving Discontinuous Bunch Trains in the MaRIE Linac	320
	J.T. Bradley III, D. Rees, A. Scheinker, R.L. Sheffield LANL, Los Alamos, New Mexico, USA
	Funding: Work supported by the US Department of Energy. The MaRIE project will use a superconducting linac to provide 12 GeV electron bunches to drive an X-ray FEL and to do electron radiography. Dynamic experiments planned for MaRIE require that the linac produce a series of micropulses that can be irregularly spaced within the macropulse, and these patterns can change from macropulse to macropulse. Irregular pulse structures create a challenge to optimizing the design of the RF and cryogenic systems. General formulas for cavities with beam loading can overestimate the power required for our irregular beam macropulse. The differing beam energy variations allowed for the XFEL and eRad micropulses produce cavity voltage control requirements that also vary within the macropulse. The RF pulse driving the cavities can be tailored to meet the needs of that particular beam macropulse because the macropulse structure is known before the pulse starts. We will derive a toolkit that can be used to determine the required RF power waveforms for arbitrary macropulse structures. We will also examine how the irregular RF power waveforms can impact RF and cryogenic system cost tradeoffs.
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MOP106018	Measurement of the Transverse Beam Dynamics in a TESLA-type Superconducting Cavity	323
SPWR025	use link to see paper's listing under its alternate paper code
	A. Halavanau, P. Piot Northern Illinois University, DeKalb, Illinois, USA N. Eddy, D.R. Edstrom, A. Lunin, P. Piot, J. Ruan, N. Solyak Fermilab, Batavia, Illinois, USA
	Funding: US Department of Energy (DOE) under contract DE-SC0011831 with Northern Illinois University. Fermilab is operated by the Fermi Research Alliance LLC under US DOE contract DE-AC02-07CH11359. Superconducting linacs are capable of producing intense, ultra-stable, high-quality electron beams that have widespread applications in Science and Industry. Many project are based on the 1.3-GHz TESLA-type superconducting cavity. In this paper we provide an update on a recent experiment aimed at measuring the transfer matrix of a TESLA cavity at the Fermilab Accelerator Science and Technology (FAST) facility. The results are discussed and compared with analytical and numerical simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOP106018
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TU3A03	Beam Commissioning of the MAX IV Linac
	S. Thorin, J. Andersson, F. Curbis, L. Isaksson, M. Kotur, D. Kumbaro, F. Lindau, E. Mansten, D. Olsson MAX IV Laboratory, Lund University, Lund, Sweden
	The MAX IV linac is used both for injection into a 3 GeV storage ring, and as a high brightness driver for a Short Pulse Facility (SPF). The linac has also been deigned to handle the high demands of an FEL injector. The first phase of beam commissioning of the linac was completed and operations for ring and SPF injection has been ongoing for several months. In this paper we present the results from beam commissioning, injections to the storage ring and SPF operation.
	Slides TU3A03 [6.245 MB]
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TUPLR005	Development of 6 MeV European S-band Side-Coupled Industrial Electron Linear Accelerator at RTX & KAERI	478
SPWR002	use link to see paper's listing under its alternate paper code
	P. Buaphad, S.C. Cha KAERI, Jeongeup-si, Republic of Korea P. Buaphad University of Science and Technology of Korea (UST), Daejeon, Republic of Korea P. Buaphad RTX, Daejeon, Republic of Korea Y. Kim ISU, Pocatello, Idaho, USA
	There are growing demands on low energy electron linear accelerator (linac) for industrial applications. Most of industrial electron linacs require a compact structure and limited undesirable neutron production to avoid huge lead shielding. Radiation Technology eXcellence (RTX) and Korea Atomic Energy Research Institute (KAERI) have developed a 6 MeV compact side-coupled linac by using 2998 MHz European S-band RF technology to meet those requirements. To design the linac structure, the 3D CST MICROWAVE STUDIO (CST-MWS) was used for various electromagnetic simulations, and ASTRA code was used for particle beam dynamics simulations. After various optimizations, the shunt impedance of 61 MΩ/m is obtained at 2998.38 MHz. With a peak RF power of 2.2 MW and a 47 cm-long structure, electron beam with a peak current of 150 mA can be accelerated from 25 keV to 6 MeV. For the industrial linac, the electron beam spotsize at an X-ray target, located 5 cm downstream of the linac structure exit should be smaller than 2 mm (FW). In addition, it can supply an X-ray dose rate of 8 Gy/min at 1 m after the X-ray target. In this paper, we describe the design concepts and optimization of the 2998 MHz side-coupled industrial linac structure.
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TUPLR009	An Iterative Learning Feedforward Controller for the TRIUMF e-linac	485
	M.P. Laverty, K. Fong TRIUMF, Vancouver, Canada
	In the TRIUMF e-linac design, beam stability to within 0.1% within 10 μs in pulse mode is a design requirement. Traditional feedback control systems cannot respond within this time frame, so some form of feedforward control is needed. Even conventional feedforward may not be sufficient due to differences between the required feedforward signal and the actual beam-loading current. For this reason, an adaptive feedforward system using an iterative learning controller was developed for the e-linac LLRF. It can anticipate repetitive beam disturbance patterns by learning from previous iterations. The design and implementation of such a control algorithm is outlined, some simulation results are presented, and some preliminary test results with an actual cavity are illustrated.
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TH3A02	The Los Alamos Multi-Probe Facility for Matter-Radiation Interactions in Extremes	729
	R.W. Garnett LANL, Los Alamos, New Mexico, USA
	Funding: This work is supported by the United States Department of Energy, National Nuclear Security Agency, under contract DE-AC52-06NA25396. A next-generation signature facility based on multi-probe capabilities is being planned at Los Alamos. This new facility will enable the first in a new generation of game-changing scientific facilities for the materials community. The new Matter-Radiation Interactions in Extremes (MaRIE) facility will be used to discover and design the advanced materials needed to meet 21st-century national security and energy-security challenges to develop next-generation materials that will perform predictably in extreme environments. The MaRIE facility will include a new 12-GeV electron linac using a state-of-the-art electron photoinjector and superconducting accelerator technology to drive a 42-keV XFEL to generate x rays of unprecedented flux and quality, coupled with the existing proton-beam capabilities of the LANSCE proton linac, new experimental halls, and new materials fabrication/characterization facilities. A description of this new facility, its requirements, and planned uses and capabilities will be presented. Status of the project will also be presented.
	Slides TH3A02 [5.060 MB]
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THOP11	Ultra-Short Bunch Electron Injector for Awake	770
THPLR071	use link to see paper's listing under its alternate paper code
	S. Döbert CERN, Geneva, Switzerland
	The proton driven plasma wake field acceleration experiment AWAKE at CERN will start at the end of this year. In 2017 an S-band electron injector producing bunches of a few ps length will be added to probe the wake fields stimulated by a driving proton beam. In the future this electron injector will have to be upgraded to obtain electron bunches with a length of 100 - 200 fs in order to demonstrate injection into a single bucket of the plasma wave and therefore sustainable acceleration with low energy spread. Target bunch parameters for the study are a bunch charge of 100 pC, 100 fs bunch length, an emittance smaller than 2 mm mrad and a beam energy of 100 MeV. The status of a study to achieve these parameters using X-band accelerator hardware and velocity bunching will be presented.
	Slides THOP11 [2.733 MB]
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THOP12	Electron Linac Upgrade for Thomx Project	773
SPWR001	use link to see paper's listing under its alternate paper code
THPLR072	use link to see paper's listing under its alternate paper code
	L. Garolfi, C. Bruni, M. El Khaldi LAL, Orsay, France N. Faure, A. Perez Delaume PMB-ALCEN, PEYNIER, France
	The injector Linac for Thomx * consists of an electron gun and S-band accelerating section. The RF gun is a 2.5 cells photo-injector able to provide electron bunches with 5 MeV energy. During the commissioning phase, a standard S-band accelerating section is able to achieve around 50 MeV corresponding to around 45 keV X-rays energy. Since the maximum targeted X-ray energy is 90 keV, the Linac design will provide a beam energy of 70 MeV. The Linac upgrade of the machine covers many different aspects. The purpose is to increase the compactness of the accelerator complex whereas the beam properties for ring injection are kept. A LAL Orsay-PMB ALCEN collaboration has been established. The program foresees the RF design, prototyping and power tests of a high-gradient compact S-band accelerating structure. To fulfill the technical specifications at the interaction point, the Linac must be carefully designed. Beam dynamics simulations have been performed for optimizing the emittance and the energy spread for the ring entrance. The best set of parameters together with the effect of the accelerating section to the beam dynamics at the end of the LINAC will be presented. * A. Variola, et al, "The Thomx Project Status", Proceedings of IPAC2014, Dresden, Germany.
	Slides THOP12 [1.726 MB]
	Poster THOP12 [0.823 MB]
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THPLR007	Dark Current Studies in ILC Main Linac	855
	A.I. Sukhanov, I.L. Rakhno, N. Solyak, I.S. Tropin Fermilab, Batavia, Illinois, USA
	Studies and optimization of design of the International Linear Collider (ILC) based on the TESLA-type 9-cell 1.3 GHz superconducting RF (SRF) cavities are currently underway. Dark current electron generated by field emission (FE) in SRF cavities can be captured and accelerated in the main ILC linac up to very high energy before they are removed by focusing and steering magnets. Dark current electrons, interacting with the materials surrounding SRF cavities, produce electromagnetic showers and contribute to the radiation in the main ILC tunnel. In this paper present preliminary results of the simulation study of dark current in the ILC linac.
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Paper

Title

Page

MO2A01

The LCLS-II SCRF Linac

M.C. Ross, A. Burrill
SLAC, Menlo Park, California, USA

The LCLS-II CW x-ray FEL is based on high Q0 1.3 GHz SCRF cavities powered by solid-state amplifiers. This talk will describe the R&D towards these cavities and the recent results of cryomodule prototypes.

Slides MO2A01 [18.815 MB]

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MO2A02

Commissioning and Plans at IOTA/FAST

D.R. Broemmelsiek, C.M. Baffes, C.I. Briegel, K. Carlson, B.E. Chase, D.J. Crawford, E. Cullerton, J.S. Diamond, N. Eddy, D.R. Edstrom, E.R. Harms, J.R. Leibfritz, A.H. Lumpkin, E. Prebys, J. Reid, J. Ruan, T. Sen, V.D. Shiltsev, G. Stancari, J.C.T. Thangaraj, R.M. Thurman-Keup, A. Valishev, A. Warner
Fermilab, Batavia, Illinois, USA
A. Halavanau, D. Mihalcea, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
J. Hyun
Sokendai, Ibaraki, Japan
P. Kobak
BYU-I, Rexburg, USA
W.D. Rush
KU, Lawrence, Kansas, USA

The electron injector at IOTA/FAST is based on a 50MeV RF photoinjector and SRF 1.3 GHz cryomodule to accelerate beam up to 300 MeV. Photoinjector and Cryomodule (CM2) were commissioned separately. CM2 demonstrated world record accelerating gradient > 30MV/m in all cavities. Commissioning of the 50MeV RF photoinjector was successfully done recently. Results of commissioning, status and plans for IOTA/FAST are presented.

Slides MO2A02 [6.248 MB]

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MO2A03

Commissioning and Early Operation of the ARIEL e-Linac

12

T. Planche, M. Alcorta, F. Ames, R.A. Baartman, C.B. Barquest, B. Humphries, D. Kaltchev, S.R. Koscielniak, R.E. Laxdal, Y. Ma, M. Marchetto, S. Saminathan, E. Thoeng
TRIUMF, Vancouver, Canada
P. Jung
UW/Physics, Waterloo, Ontario, Canada

The ARIEL electron linac has been added to the TRIUMF facility as a new driver for the production of radioactive isotopes through photo-fission to complement the existing 500 MeV, H^- TRIUMF cyclotron. The electron beam driver is specified as a 50 MeV, 10 mA cw superconducting electron linac at 1.3 GHz. The first 30 MeV stage of the e-linac consisting of two cryomodules is completed. The paper will describe the recent commissioning and early operation results.

Slides MO2A03 [25.277 MB]

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MO2A04

Low Emittance and High Current Electron Linac Development at Tsinghua University

17

C.-X. Tang, H.B. Chen, Z.J. Chi, Y.-C. Du, W.-H. Huang, J. Shi, Q.L. Tian, D. Wang, W. Wang, L.X. Yan, Z. Zhang, Z. Zhang, L.M. Zheng, Z. Zhou
TUB, Beijing, People's Republic of China

A 50MeV electron linac have been developed in Tsinghua University, which consists of a 1.6Cell photocathode rf gun, a 3-meter s-band SLAC type traveling wave (TW) accelerating structure an a s-band TW buncher. The photocathode rf gun is working at 120MV/m, 2856MHz, with very small dark current. The emittance of the electron beam is less than 1mm.mrad at 500pC, and 0.5mm.mrad at 200pC. The linac is designed for Tsinghua Thomson scattering X-ray source (TTX), and 2x10⁷ photon/bunch at 50keV has been got and some application experiments with the x-ray have been carried out. The new photocathode rf gun and x-band high gradient accelerating structure development will also be introducted in this talk.

Slides MO2A04 [11.413 MB]

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MO3A01

Status of SwissFEL

22

F. Löhl
PSI, Villigen PSI, Switzerland

SwissFEL is a hard x-ray free-electron laser facility that is currently constructed at PSI. This paper gives an overview of the facility, describes the main sub-systems of the accelerator, and summarizes the installation and commissioning status.

Slides MO3A01 [315.102 MB]

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MOOP11

Operation of the CEBAF 100 MV Cryomodules

65

MOPLR003

use link to see paper's listing under its alternate paper code

C. Hovater, T.L. Allison, R. Bachimanchi, G.H. Biallas, E. Daly, M.A. Drury, A. Freyberger, R.L. Geng, G.E. Lahti, R.A. Legg, C.I. Mounts, R.M. Nelson, T. E. Plawski, T. Powers
JLab, Newport News, Virginia, USA

Funding: Authored by JSA, LLC under U.S. DOE Contract DE-AC05- 06OR23177.
The Continuous Electron Beam Accelerator Facility (CEBAF) 12 GeV upgrade reached its design energy in December of 2015. Since then CEBAF has been delivering 12 GeV beam to experimental Hall D and 11 GeV to experimental halls A and B in support of Nuclear physics. To meet this energy goal, ten new 100 MV cryomodules (80 cavities) and RF systems were installed in 2013. The superconducting RF cavities are designed to operate CW at a average accelerating gradient of 19.2 MV/m. To support the higher gradients and higher QL (3.2×107) operations, the RF system uses 13 kW klystrons and digital LLRF to power and control each cavity. This paper reports on the C100 operation and optimization improvements of the RF system and cryomodules.

Slides MOOP11 [1.574 MB]

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MOPLR004

Development of an High Gradient, S-band, Accelerating Structure for the FERMI Linac

136

C. Serpico, I. Cudin
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
A. Grudiev
CERN, Geneva, Switzerland

The FERMI seeded free-electron laser (FEL), located at the Elettra laboratory in Trieste, is driven by a 200 meter long, S-band linac routinely operated at nearly 1.5 GeV and 10 Hz repetition rate [1]. The high energy part of the Linac is equipped with seven, 6 meter long Backward Traveling Wave (BTW) structures: those structures have small iris radius and a nose cone geometry which allows for high gradient operation [2]. Nonetheless a possible development of high-gradient, S-band accelerating struc-tures for the replacement of the actual BTW structures is under consideration. This paper investigates a possible solution for RF couplers that could be suitable for linac driven FEL where reduced wakefields effects, high oper-ating gradient and very high reliability are required.

Poster MOPLR004 [0.947 MB]

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MOPLR005

Design, Manufacturing and Installation of Two Dual-Feed Accelerating Structures for the FERMI Injector

139

C. Serpico, A. Fabris, G. Penco, M. Svandrlik
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
B. Keune
RI Research Instruments GmbH, Bergisch Gladbach, Germany

FERMI is a seeded Free Electron Laser (FEL) driven by a warm S-band Linac. In the injector region, two 3- meter long Forward Traveling Wave (FTW) accelerating structures, coming from the old Elettra injector, were installed. In order to improve the e-beam quality at higher bunch charge, it was decided to replace the existing ones with two dual-feed accelerating structures. Those structures have been designed and manufactured by RI Research Instruments GmbH and delivered to Elettra in July 2015. The following paper will report about the RF design and the manufacturing of the new structures. Details about the RF conditioning and the installation will also be illustrated.

Poster MOPLR005 [1.100 MB]

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MOPLR006

Monopole HOMs Dumping in the LCLS-II 1.3 GHz Structure

142

A. Lunin, T.N. Khabiboulline, N. Solyak
Fermilab, Batavia, Illinois, USA

Funding: Operated by Fermi Research Alliance, LLC, under Contract DE-AC02-07CH11359 with the U.S. DOE
Developing an upgrade of Linac Coherent Light Source (LCLS-II) is currently underway. The central part of LCLS-II is a continuous wave superconducting RF (CW SRF) electron linac. High order modes (HOMs) excited in SRF structures by passing beam may deteriorate beam quality and affect beam stability. In this paper we report the simulation results of monopole High Order Modes (HOM) spectrum in the 1.3 GHz accelerating structure. Optimum parameters of the HOM feedthrough are suggested for minimizing RF losses on the HOM antenna tip and for preserving an efficiency of monopole HOMs damping simultaneously.

Poster MOPLR006 [0.647 MB]

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MOPLR007

Redesign of the End Group in the 3.9 GHz LCLS-II Cavity

145

A. Lunin, I.V. Gonin, T.N. Khabiboulline, N. Solyak
Fermilab, Batavia, Illinois, USA

Funding: Operated by Fermi Research Alliance, LLC, under Contract DE-AC02-07CH11359 with the U.S. DOE
Development and production of Linac Coherent Light Source II (LCLS-II) is underway. The central part of LCLS-II is a continuous wave superconducting RF (CW SCRF) electron linac. The 3.9 GHz third harmonic cavity similar to the XFEL design will be used in LCLS-II for linearizing the longitudinal beam profile*. The initial design of the 3.9 GHz cavity developed for XFEL project has a large, 40 mm, beam pipe aperture for better higher-order mode (HOM) damping. It is resulted in dipole HOMs with frequencies nearby the operating mode, which causes difficulties with HOM coupler notch filter tuning. The CW linac operation requires an extra caution in the design of the HOM coupler in order to prevent its possible overheating. In this paper we present the modified 3.9 GHz cavity End Group for meeting the LCLS-II requirements
* LCLS-II 3.9 GHz Cryomodules, Physics Requirements Document, LCLSII-4.1-PR-0097-R1, SLAC, USA, 2015

Poster MOPLR007 [1.590 MB]

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MOPLR008

Status Of the ILC Main Linac Design

149

A. Saini, V.V. Kapin, N. Solyak
Fermilab, Batavia, Illinois, USA

International Linear collider (ILC) is a proposed accelerator facility which is primarily based on two 11-km long superconducting main linacs. In this paper we present recent updates on the main linac design and discuss changes made in order to meet specification outlined in the technical design report (TDR).

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MOPLR009

X-Band Travelling Wave Accelerating Section R&D for HTF

152

K. Jin
USTC/NSRL, Hefei, Anhui, People's Republic of China

Hefei Light Source (HLS) was mainly composed of an 800 MeV electron storage ring and an 800MeV-1GeV constant-gradient accelerator in NSRL. The new Linac with Full Energy Injection and the Top-up Injection scheme has been developed successfully. And the other functioning as X Ray Free Electron Laser test facility has been considered. In the project, in order to compress the bunch length and to achieve the beam energy distribution linearization. A 15MeV, operation frequency 11.424GHz traveling wave accelerating section as harmonic compensation is being developed. In this paper, X Ray Free Electron Laser Hefei Test Facility (HTF) is introduce briefly. And the R&D of the x-band accelerating section with collinear load are presented in detail.

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MOPLR010

4 K SRF Operation of the 10 MeV CEBAF Photo-Injector

155

G.V. Eremeev, M.A. Drury, J.M. Grames, R. Kazimi, M. Poelker, J.P. Preble, R. Suleiman, Y.W. Wang, M. Wright
JLab, Newport News, Virginia, USA

Funding: Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
SRF accelerating cavities are often operated in superfluid helium of temperature near 2 K to enhance the cavity quality factor Q0 and manage cryogenic heat loads, which are particularly important at large SRF accelerator facilities. This temperature paradigm, however, need not put SRF technology out of the reach of small institutions or even limit SRF operation at large facilities to provide 10-100 MeV beam energy. At the Jefferson Lab CEBAF accelerator there are regularly scheduled maintenance periods during which the liquid helium temperature is raised to 4 K, reducing cryogenic plant power consumption by ~50% and saving megawatts of electrical power. During such a recent period, we accelerated a continuous-wave electron beam at the CEBAF photo-injector to 6.3 MeV/c with current ~80μA using two niobium cavities at helium temperature of 4 K. This contribution describes the SRF and cryogenic performance and uses measured beam quality and energy stability as key metrics. These measurements indicate that 4 K operation of niobium SRF cavities in CEBAF and at small institutions may be a sensible and cost effective mode of operation, provided the cryogenic load associated with lower Q0 is manageable for the number of SRF cavities needed. For Jefferson Lab, this enhances our scientific reach allowing additional low-energy ~10 MeV experiments each year.

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MOPLR011

Design of a Dielectric-lined Waveguide for Terahertz-driven Linear Electron Acceleration

158

SPWR012

use link to see paper's listing under its alternate paper code

A.L. Healy, G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
M.J. Cliffe, D.M. Graham
The University of Manchester, The Photon Science Institute, Manchester, United Kingdom
S.P. Jamison
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
R. Valizadeh
Cockcroft Institute, Warrington, Cheshire, United Kingdom

A dielectric-lined waveguide has been designed for use as an accelerating structure in terahertz-driven electron acceleration experiments at Daresbury. Experimental verification of acceleration will take place on Versatile Electron Linear Accelerator (VELA). The choice of a rectangular waveguide structure with sidewall dielectric layers enables tuning by varying the spacing between dielectric slabs to account for potential manufacturing errors. Schemes for coupling free-space single cycle THz pulses into the waveguide have been evaluated and optimised through CST simulation. Comparison of simulation with experimental measurements will also be presented.

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MOPLR012

Compact Beam Position Monitor for Electron and Proton Machines

161

M. Žnidarčič, M. Cargnelutti
I-Tech, Solkan, Slovenia

Monitoring and subsequent optimization of the linacs, transfer lines, energy recovery linacs and synchrotrons, requires specific instrumentation optimized for beam position and charge measurements. Libera Spark is the newly developed instrument intended for position and charge monitoring in electron and proton machines. The motivation, processing principles and first results at laboratories are presented.

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MOPLR013

Investigations on Electron Beam Imperfections at PITZ

165

M. Krasilnikov, P. Boonpornprasert, J.D. Good, M. Groß, H. Huck, I.I. Isaev, D.K. Kalantaryan, O. Lishilin, G. Loisch, D. Melkumyan, A. Oppelt, G. Pathak, Y. Renier, T. Rublack, F. Stephan, G. Vashchenko, Q.T. Zhao
DESY Zeuthen, Zeuthen, Germany
G. Asova
INRNE, Sofia, Bulgaria
C. Hernandez-Garcia
JLab, Newport News, Virginia, USA

Since more than a decade, the photo injector test facility at DESY, Zeuthen site (PITZ), has developed and optimized high brightness electron sources for modern Free Electros Lasers like FLASH and the European XFEL. Despite a very high performance of the photo injector was experimentally demonstrated, several discrepancies between measurements and beam dynamics simulations have been revealed. Although the optimized measured values of the projected transverse emittance are close to those obtained from the beam dynamics simulations, the corresponding experimental machine parameters show certain systematic deviations from the simulated optimized setup. As a source for these deviations, electron beam imperfections were experimentally investigated. This includes studies on bunch charge production, electron beam imaging using the RF gun with its solenoid, and investigations on the transverse asymmetry of the electron beam generated in a rotationally symmetric gun cavity. Experimental studies were supplied with corresponding beam dynamics simulations. The paper reports on results of these studies.

Poster MOPLR013 [2.140 MB]

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MOPLR014

Construction of a Third Recirculation for the S-DALINAC*

168

M. Arnold, T. Kürzeder, J. Pforr, N. Pietralla, M. Steinhorst
TU Darmstadt, Darmstadt, Germany
F. Hug
IKP, Mainz, Germany

Funding: * Work supported by DFG through CRC 634 and RTG 2128
Since 1991 the superconducting recirculating electron accelerator S-DALINAC is running at TU Darmstadt. Its designated design energy of 130 MeV wasn't reached yet due to a lower quality factor of the 3 GHz cavities and thus a higher dissipated power to the helium bath. To increase the maximum achievable energy in cw operation from approx. 85 MeV to the design value of 130 MeV the main accelerator will be passed a fourth time. In this configuration the accelerating gradients of the cavities can be lowered, so that the resulting dissipated power will match the available cooling power of the cryo plant. To realize an additional main linac pass a new recirculation beam line is needed. The most crucial points are the design of the separation dipole and its mirrored version as well as a properly calculated lattice. For the implementation of a new recirculation beam line the existing sections must be adapted to fit the new boundary conditions. This contribution will present some aspects of the design and will report on the actual status of this project.

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MOPLR015

Thermal-Mechanical Study of 3.9 GHz CW Coupler and Cavity for LCLS-II Project

171

I.V. Gonin, E.R. Harms, T.N. Khabiboulline, N. Solyak, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

Third harmonic system was originally developed by Fermilab for FLASH facility at DESY and then was adopted and modified by INFN for the XFEL project [1-3]. In contrast to XFEL project, all cryomodules in LCLS-II project will operate in CW regime with higher RF average power for 1.3 GHz and 3.9 GHz cavities and couplers. Design of the cavity and fundamental power coupler has been modified to satisfy LCLS-II requirements. In this paper we discuss the results of COMSOL thermal and mechanical analysis of the 3.9 GHz coupler and cavity to verify proposed modifica-tion of the design. For the dressed cavity we present simulations of Lorentz force detuning, helium pressure sensitivity df/dP and major mechanical resonances.

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MOPLR016

Status of the Injection System of the CLARA FEL Test Facility

174

B.L. Militsyn, D. Angal-Kalinin, R.K. Buckley, R.J. Cash, J.A. Clarke, L.S. Cowie, B.D. Fell, P. Goudket, T.J. Jones, K.B. Marinov, P.A. McIntosh, J.W. McKenzie, K.J. Middleman, T.C.Q. Noakes, B.J.A. Shepherd, R. Valizadeh, A.E. Wheelhouse
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
V.V. Paramonov
RAS/INR, Moscow, Russia

The 250 MeV CLARA FEL test facility is now under construction at Daresbury Laboratory. Electron beam for this facility is provided by two normal conducting S-band photocathode guns: a 10 Hz 2.5 cell gun earlier used as the injector for the VELA machine, and a 400 Hz 1.5 cell gun now under commissioning. At the initial stage of Phase I CLARA will operate with the 10 Hz gun and a 45 MeV 2 m long linac section working as a buncher and/or booster. The beam will be deflected into the existing VELA beamline with an S-bend and directed to the spectrometer line for analysing beam properties or into one of two VELA user areas. The 400 Hz gun will be installed in the VELA beamline for detailed high power RF and beam commissioning in the VELA beam diagnostics suite. As the 400 Hz gun is equipped with an interchangeable photocathode it is possible to investigate different metal photocathodes and select the one providing minimal beam emittance at highest quantum efficiency. A state of the art photocathode preparation system is under commissioning at Daresbury. After commissioning the 400 Hz gun will be installed to the CLARA beam line to deliver high energy, high repetition rate beams for the FEL facility, and the 10 Hz gun will be returned to the VELA beam line.

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MOPLR018

Upgrade of the Klystron Modulator of the L-Band Electron Linac at Osaka University for Higher Stability

178

K. Furukawa, G. Isoyama
ISIR, Osaka, Japan
R. Kato
KEK, Ibaraki, Japan
K. Kawase
HSRC, Higashi-Hiroshima, Japan
A. Tokuchi
Pulsed Power Japan Laboratory Ltd., Kusatsu-shi Shiga, Japan

The klystron modulator for the L-band linac is upgraded for higher stability. The two-step charging system for the pulse forming network (PFN) is upgraded by adding a high impedance resonant charging line in parallel with the main line. The charging step of the PFN voltage is reduced considerably near the setting value by switching the main resonance line off so that the charging current flows only through the high impedance line. The second model of the solid-state switch is developed using 60 static-induction thyristors, ten of which are connected in series with six such series connected in parallel to meet maximum specifications of 25 kV and 6 kA. The air-cooling capacity is reinforced so that repetition rate is increased from 10 pps for the first model to 60 pps. The fluctuation and accuracy of the klystron voltage are measured to be 7.8×10^-6 or 7.8 ppm for the upgraded klystron modulator using a differential amplifier with much higher sensitivity than one used in the previous measurement.

Poster MOPLR018 [0.840 MB]

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MOPLR020

Challenges in Realizing the LCLS-II Cryomodule Production

181

A. Burrill
SLAC, Menlo Park, California, USA

The LCLS-II project requires the assembly and installation of 37 cryomodules in order to deliver a 4 GeV electron beam to the undulators to produce both soft and hard x-rays at a repetition rate up to 1 MHz. All of the cryomodules will operate in continuous wave mode, with 35 operating at 1.3 GHz for acceleration and 2 operating at 3.9 GHz to linearize the longitudinal beam profile. One of the challenges of this project, and the topic of this paper, is coordinating the effort of three DOE labs in order to realize this machine in just a few years time. This coordination is necessary due to the fact that the cryomodules will be assembled at both Jefferson Lab and Fermi Lab, tested, and then shipped to SLAC for installation, commissioning and operation. This paper will report on our experiences to date, issues that have been identified and planned mitigation going forward.

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MOP106015

Commissioning Status of the Chopper System for the MAX IV Injector

316

D. Olsson, J. Andersson, F. Curbis, L. Isaksson, L. Malmgren, E. Mansten, S. Thorin
MAX IV Laboratory, Lund University, Lund, Sweden

The MAX IV facility in Lund, Sweden consists of two storage rings for production of synchrotron radiation. The two rings are designed for 1.5 GeV and 3 GeV, respectively, where the former is under construction, and the latter is undergoing beam commissioning. Both rings will be operating with top-up injections delivered by a full-energy injector that consists of 39 traveling-wave S-band LINAC structures. In order to reduce losses of high-energy electrons along the injector and in the rings during injection, only electrons that are within an allowed time structure are accelerated. This time structure depends on several parameters such as the available RF voltage and the radiation losses in the ring that is about to be injected, but also on the momentum acceptance of the transport lines in the injector. The electrons that are outside the allowed time structure are dumped when they have energies below 3 MeV by a chopper system that is located between a thermionic RF gun and the first LINAC structure. Basically, the chopper system consists of two planar striplines and a variable aperture, and the first stripline is fed with a superposed RF signal and the second one with HV pulses. The performance of the chopper system during commissioning of the 3 GeV ring is presented in this article.

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MOP106016

High Power RF Requirements for Driving Discontinuous Bunch Trains in the MaRIE Linac

320

J.T. Bradley III, D. Rees, A. Scheinker, R.L. Sheffield
LANL, Los Alamos, New Mexico, USA

Funding: Work supported by the US Department of Energy.
The MaRIE project will use a superconducting linac to provide 12 GeV electron bunches to drive an X-ray FEL and to do electron radiography. Dynamic experiments planned for MaRIE require that the linac produce a series of micropulses that can be irregularly spaced within the macropulse, and these patterns can change from macropulse to macropulse. Irregular pulse structures create a challenge to optimizing the design of the RF and cryogenic systems. General formulas for cavities with beam loading can overestimate the power required for our irregular beam macropulse. The differing beam energy variations allowed for the XFEL and eRad micropulses produce cavity voltage control requirements that also vary within the macropulse. The RF pulse driving the cavities can be tailored to meet the needs of that particular beam macropulse because the macropulse structure is known before the pulse starts. We will derive a toolkit that can be used to determine the required RF power waveforms for arbitrary macropulse structures. We will also examine how the irregular RF power waveforms can impact RF and cryogenic system cost tradeoffs.

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MOP106018

Measurement of the Transverse Beam Dynamics in a TESLA-type Superconducting Cavity

323

SPWR025

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A. Halavanau, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
N. Eddy, D.R. Edstrom, A. Lunin, P. Piot, J. Ruan, N. Solyak
Fermilab, Batavia, Illinois, USA

Funding: US Department of Energy (DOE) under contract DE-SC0011831 with Northern Illinois University. Fermilab is operated by the Fermi Research Alliance LLC under US DOE contract DE-AC02-07CH11359.
Superconducting linacs are capable of producing intense, ultra-stable, high-quality electron beams that have widespread applications in Science and Industry. Many project are based on the 1.3-GHz TESLA-type superconducting cavity. In this paper we provide an update on a recent experiment aimed at measuring the transfer matrix of a TESLA cavity at the Fermilab Accelerator Science and Technology (FAST) facility. The results are discussed and compared with analytical and numerical simulations.

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TU3A03

Beam Commissioning of the MAX IV Linac

S. Thorin, J. Andersson, F. Curbis, L. Isaksson, M. Kotur, D. Kumbaro, F. Lindau, E. Mansten, D. Olsson
MAX IV Laboratory, Lund University, Lund, Sweden

The MAX IV linac is used both for injection into a 3 GeV storage ring, and as a high brightness driver for a Short Pulse Facility (SPF). The linac has also been deigned to handle the high demands of an FEL injector. The first phase of beam commissioning of the linac was completed and operations for ring and SPF injection has been ongoing for several months. In this paper we present the results from beam commissioning, injections to the storage ring and SPF operation.

Slides TU3A03 [6.245 MB]

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TUPLR005

Development of 6 MeV European S-band Side-Coupled Industrial Electron Linear Accelerator at RTX & KAERI

478

SPWR002

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P. Buaphad, S.C. Cha
KAERI, Jeongeup-si, Republic of Korea
P. Buaphad
University of Science and Technology of Korea (UST), Daejeon, Republic of Korea
P. Buaphad
RTX, Daejeon, Republic of Korea
Y. Kim
ISU, Pocatello, Idaho, USA

There are growing demands on low energy electron linear accelerator (linac) for industrial applications. Most of industrial electron linacs require a compact structure and limited undesirable neutron production to avoid huge lead shielding. Radiation Technology eXcellence (RTX) and Korea Atomic Energy Research Institute (KAERI) have developed a 6 MeV compact side-coupled linac by using 2998 MHz European S-band RF technology to meet those requirements. To design the linac structure, the 3D CST MICROWAVE STUDIO (CST-MWS) was used for various electromagnetic simulations, and ASTRA code was used for particle beam dynamics simulations. After various optimizations, the shunt impedance of 61 MΩ/m is obtained at 2998.38 MHz. With a peak RF power of 2.2 MW and a 47 cm-long structure, electron beam with a peak current of 150 mA can be accelerated from 25 keV to 6 MeV. For the industrial linac, the electron beam spotsize at an X-ray target, located 5 cm downstream of the linac structure exit should be smaller than 2 mm (FW). In addition, it can supply an X-ray dose rate of 8 Gy/min at 1 m after the X-ray target. In this paper, we describe the design concepts and optimization of the 2998 MHz side-coupled industrial linac structure.

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TUPLR009

An Iterative Learning Feedforward Controller for the TRIUMF e-linac

485

M.P. Laverty, K. Fong
TRIUMF, Vancouver, Canada

In the TRIUMF e-linac design, beam stability to within 0.1% within 10 μs in pulse mode is a design requirement. Traditional feedback control systems cannot respond within this time frame, so some form of feedforward control is needed. Even conventional feedforward may not be sufficient due to differences between the required feedforward signal and the actual beam-loading current. For this reason, an adaptive feedforward system using an iterative learning controller was developed for the e-linac LLRF. It can anticipate repetitive beam disturbance patterns by learning from previous iterations. The design and implementation of such a control algorithm is outlined, some simulation results are presented, and some preliminary test results with an actual cavity are illustrated.

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TH3A02

The Los Alamos Multi-Probe Facility for Matter-Radiation Interactions in Extremes

729

R.W. Garnett
LANL, Los Alamos, New Mexico, USA

Funding: This work is supported by the United States Department of Energy, National Nuclear Security Agency, under contract DE-AC52-06NA25396.
A next-generation signature facility based on multi-probe capabilities is being planned at Los Alamos. This new facility will enable the first in a new generation of game-changing scientific facilities for the materials community. The new Matter-Radiation Interactions in Extremes (MaRIE) facility will be used to discover and design the advanced materials needed to meet 21st-century national security and energy-security challenges to develop next-generation materials that will perform predictably in extreme environments. The MaRIE facility will include a new 12-GeV electron linac using a state-of-the-art electron photoinjector and superconducting accelerator technology to drive a 42-keV XFEL to generate x rays of unprecedented flux and quality, coupled with the existing proton-beam capabilities of the LANSCE proton linac, new experimental halls, and new materials fabrication/characterization facilities. A description of this new facility, its requirements, and planned uses and capabilities will be presented. Status of the project will also be presented.

Slides TH3A02 [5.060 MB]

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THOP11

Ultra-Short Bunch Electron Injector for Awake

770

THPLR071

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S. Döbert
CERN, Geneva, Switzerland

The proton driven plasma wake field acceleration experiment AWAKE at CERN will start at the end of this year. In 2017 an S-band electron injector producing bunches of a few ps length will be added to probe the wake fields stimulated by a driving proton beam. In the future this electron injector will have to be upgraded to obtain electron bunches with a length of 100 - 200 fs in order to demonstrate injection into a single bucket of the plasma wave and therefore sustainable acceleration with low energy spread. Target bunch parameters for the study are a bunch charge of 100 pC, 100 fs bunch length, an emittance smaller than 2 mm mrad and a beam energy of 100 MeV. The status of a study to achieve these parameters using X-band accelerator hardware and velocity bunching will be presented.

Slides THOP11 [2.733 MB]

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THOP12

Electron Linac Upgrade for Thomx Project

773

SPWR001

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THPLR072

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L. Garolfi, C. Bruni, M. El Khaldi
LAL, Orsay, France
N. Faure, A. Perez Delaume
PMB-ALCEN, PEYNIER, France

The injector Linac for Thomx * consists of an electron gun and S-band accelerating section. The RF gun is a 2.5 cells photo-injector able to provide electron bunches with 5 MeV energy. During the commissioning phase, a standard S-band accelerating section is able to achieve around 50 MeV corresponding to around 45 keV X-rays energy. Since the maximum targeted X-ray energy is 90 keV, the Linac design will provide a beam energy of 70 MeV. The Linac upgrade of the machine covers many different aspects. The purpose is to increase the compactness of the accelerator complex whereas the beam properties for ring injection are kept. A LAL Orsay-PMB ALCEN collaboration has been established. The program foresees the RF design, prototyping and power tests of a high-gradient compact S-band accelerating structure. To fulfill the technical specifications at the interaction point, the Linac must be carefully designed. Beam dynamics simulations have been performed for optimizing the emittance and the energy spread for the ring entrance. The best set of parameters together with the effect of the accelerating section to the beam dynamics at the end of the LINAC will be presented.
* A. Variola, et al, "The Thomx Project Status", Proceedings of IPAC2014, Dresden, Germany.

Slides THOP12 [1.726 MB]

Poster THOP12 [0.823 MB]

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THPLR007

Dark Current Studies in ILC Main Linac

855

A.I. Sukhanov, I.L. Rakhno, N. Solyak, I.S. Tropin
Fermilab, Batavia, Illinois, USA

Studies and optimization of design of the International Linear Collider (ILC) based on the TESLA-type 9-cell 1.3 GHz superconducting RF (SRF) cavities are currently underway. Dark current electron generated by field emission (FE) in SRF cavities can be captured and accelerated in the main ILC linac up to very high energy before they are removed by focusing and steering magnets. Dark current electrons, interacting with the materials surrounding SRF cavities, produce electromagnetic showers and contribute to the radiation in the main ILC tunnel. In this paper present preliminary results of the simulation study of dark current in the ILC linac.

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