IPAC2017 - List of Keywords (undulator)

Paper	Title	Other Keywords	Page
MOXAA1	Commissioning of the European XFEL Accelerator	linac, operation, electron, emittance	1
	W. Decking, H. Weise DESY, Hamburg, Germany
	The European XFEL uses the world's largest superconducting RF installation to drive three independent SASE FELs. After eight years of construction the facility is now brought into operation. First experience with the superconducting accelerator as well as beam commissioning results will be presented. The path to the first user experiments will be laid down.
	Slides MOXAA1 [22.967 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOXAA1
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MOPAB050	Reconstruction of Sub-Femtosecond Longitudinal Bunch Profile Measurement Data	laser, electron, diagnostics, cavity	207
	M.K. Weikum, R.W. Aßmann, U. Dorda DESY, Hamburg, Germany G. Andonian RadiaBeam, Santa Monica, California, USA G. Andonian UCLA, Los Angeles, California, USA Z.M. Sheng, M.K. Weikum USTRAT/SUPA, Glasgow, United Kingdom Z.M. Sheng Shanghai Jiao Tong University, Shanghai, People's Republic of China
	With a current trend towards shorter electron beams with lengths on the order of few femtoseconds (fs) to sub-femtoseconds both in conventional and novel accelerator communities, the need for diagnostics with equivalent attosecond resolution is increasing. The proposed design for a sub-femtosecond diagnostic by Andonian et al.* is one such example that combines a laser deflector with an RF deflecting cavity to streak the electron beam in the horizontal and vertical direction. In this paper, we present a tool for the reconstruction of the longitudinal beam profile from this diagnostic data, which can be used both for the analysis of planned experiments and testing of different beam scenarios with respect to their specific setup requirements. Applying this method, the usefulness of the device for measurements in a number of example scenarios, including plasma-accelerated and ultrashort RF-accelerated electron beams, is discussed. *G. Andonian, E. Hemsing, D. Xiang, P. Mumuseci, A. Murokh, S. Tochitsky, et al, Phys. Rev. Spec. Top-Ac. 14, 072802 (2011).
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MOPAB051	Progress in FLASH Optics Consolidation	optics, emittance, gun, laser	211
	J. Zemella, M. Vogt DESY, Hamburg, Germany
	FLASH is the superconducting soft X-ray Free Electron Laser in Hamburg at DESY, Germany. A precise knowledge of the beam optics is a key aspect of the operation of a SASE FEL. A campaign of optics consolidation has started in 2013 when the second beam line FLASH2 was installed downstream of the FLASH linac. We give an update on progress of this effort and on recent results.
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MOPAB075	Measurement of Electron Bunch Length via a Tunable-Gap Undulator	radiation, electron, laser, acceleration	295
	X.L. Su, Y.-C. Du, W.-H. Huang, L. Niu, C.-X. Tang, Q.L. Tian, D. Wang, L.X. Yan TUB, Beijing, People's Republic of China Y.F. Liang Tsinghua University, Beijing, People's Republic of China
	A THz undulator with widely tunable gap is constructed and installed at Tsinghua University beamline, which is applied for narrow-band THz radiation and measurements of electron bunch longitudinal structure. This is a planar electromagnetic device with 8 regular periods, each 10 cm long. The field range B=0.15- 0.99 T peak field on axis while changing the gap from 75mm to 23mm. In the experiments, we scanned the undulator gap to measure the radiation intensity at different resonant frequency, thus we can get the bunch length even form factor of the bunch. The demonstrated experimental results show that the bunch of 220pC compressed by chicane in Tsinghua beamline is about 120fs (rms), which agree well with the simulations. The resolution of bunch length measurement with this method can be attoseconds by optimized undulator. Furthermore, the form factor of electron bunch train can also be measured.
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MOPAB149	Design of LCLS-II ATCA BPM System	linac, network, FEL, controls	477
	A. Young, R. Claus, J.M. D'Ewart, J.C. Frisch, G. Haller, R.T. Herbst, S. L. Hoobler, U. Legat, J.J. Olsen, R. Ruckman, L. Sapozhnikov, S.R. Smith, T. Straumann, J.A. Vásquez, M. Weaver, E. Williams, C. Xu SLAC, Menlo Park, California, USA
	Funding: Work supported by U.S. Department of Energy under Contract Numbers DE-AC02-06CH11357 SLAC's LCLS-II is a next generation X-ray FEL that will use a CW 4 GeV superconducting linac with nominal bunch spacing of 1us will deliver both soft and hard x-ray FEL to users. In order to achieve the required performance, the SLAC Technical Innovation Directorate has developed a common hardware and firmware platform for beam instrumentation based on the ATCA crate format. We have designed a stripline and cavity BPM system based on this platform that is capable of measuring the beam position at full beam rate. The system will have a dynamic range between 1 pC to 300 pC. This paper will discuss the design of the BPM electronics, overall architecture and performance on LCLS-I.
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MOPIK069	Approximate Matrices for Modeling the Focusing of the Undulator Periods and Undulator End Fields	focusing, betatron, dipole, laser	686
	V. Balandin, N. Golubeva DESY, Hamburg, Germany
	We describe procedure for constructing approximate matrices for modeling the focusing of the undulator periods and undulator end fields and discuss applicability of these matrices to the European XFEL undulators.
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MOPIK078	Narrow-Band, Wide-Range Tuneable THz Source Based on the Slotted-Foil Technique	electron, radiation, simulation, FEL	712
	J. Pfingstner, E. Adli, H. Holmestad University of Oslo, Oslo, Norway S. Bettoni, S. Reiche PSI, Villigen PSI, Switzerland
	The FEL user community has expressed a strong interest in a THz source for the excitation of their samples in pump probe experiments. The demanded THz properties are challenging to achieve, as they include a narrow bandwidth of <5-10%, the possibility of frequency tuning between 1 and 20 THz, a THz pulse energy of about 100 uJ, and a fixed phase relation from shot-to-shot. To fulfil these specifications, an accelerator-based source is proposed in this paper. It utilises the slotted-foil technique to create a pre-bunched electron beam that is injected into a helical undulator. Detailed simulation studies presented in this paper show that the corresponding undulator radiation has the demanded properties.
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MOPVA002	Initial Stage of Self Amplified Radiation Emission From Electron Bunches in Crystal: Linear Response Theory	radiation, electron, brightness, polarization	848
	A.I. Benediktovitch, I. Lobach BSU, Minsk, Belarus, Belarus
	Self amplified spontaneous emission (SASE) is a key process in X-ray free electron lasers' operation. In this case the spontaneous emission is undulator radiation emission, the radiation in X-ray range being possible from electrons in GeV energy range. In the case of interaction of electrons with properly aligned crystal the channeling radiation results in X-rays from electrons with energies in tens MeV energy range. In this situation for high current densities the SASE process may take place that potentially could lead to construction of a compact bright X-ray source. In present contribution the first principle theoretical description is outlined and first order perturbation theory is used to model the initial stage of SASE. The transition from spontaneous to SASE regime is described, the requirements for bunch current and emittance are determined. By means of dispersion equation analysis and boundary condition application the intensity radiated from crystal slab is calculated and it is shown that Bragg diffraction could enhance self amplification. A numerical example for Si (001) illustrates the model.
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MOPVA004	Operating Simultaneously Two In-Vacuum Canted Undulators in Synchrotron SOLEIL	photon, vacuum, radiation, electron	851
	L.S. Nadolski, Y.-M. Abiven, P. Brunelle, N. Béchu, M.-E. Couprie, F.J. Cullinan, X. Delétoille, M. El Ajjouri, C. Herbeaux, N. Hubert, N. Jobert, M. Labat, J.-F. Lamarre, A. Lestrade, A. Loulergue, O. Marcouillé, P. Monteiro, A. Nadji, R. Nagaoka, D. Pédeau, P. Rommeluère, K.T. Tavakoli, M. Valléau, J. Vétéran SOLEIL, Gif-sur-Yvette, France C. Benabderrahmane ESRF, Grenoble, France
	Each long SOLEIL beamline, ANATOMIX and Nanoscopium, takes a photon beam from an in-vacuum undulator with a minimum gap of 5.5 mm. The canted radiation sources are installed in a long straight section of the storage ring. The first closure of both undulators led to the severe damage of the downstream undulator in 2011. The reason for this incident has been investigated and clearly identified. A long-term project has enabled us to find a technical solution for a simultaneous operation of both undulators. A special angle fast interlock was designed and a dedicated photon absorber has been introduced at the entrance of the second undulator while keeping the impact on the beam performance as low as possible. The main technical steps will be reported with an interim solution put in place in spring 2015 and a final solution deployed and validated in May 2016.
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MOPVA026	Effects of Insertion Devices on Stored Electron Beam of High Energy Photon Source	photon, emittance, insertion, brilliance	911
	X.Y. Li, Z. Duan, D. Ji, Y. Jiao, Y.F. Yang IHEP, Beijing, People's Republic of China
	The High Energy Photon Source (HEPS) is a 4th generation, 6-Gev, ultralow-emittance, photon source project in China. High brightness hard X-ray beams at the energy particularly above 10kev are provided by insertion devices installed in straight sections of the storage ring. Brightness tuning curves of 14 ID beamlines planned in HEPS first stage are obtained after designing their parameters. However the presence of these insertion devices produce several effects on the beam performances including betatron tunes, betatron amplitude functions, closed orbit, emittance and dynamic aperture etc. It is found that the vertical octupole effect due to the fourteen IDs under the present schemes produce the most significant effect on the vertical dynamic aperture reduction. The ID field error effects on close orbit can be completely compensated by two correctors adjacent the ID at the both side. The horizontal emittance reduces to 36pm.rad due to the damping wiggler effect of IDs with field error after the orbit correction is also obtained.
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MOPVA033	A Compact Thermionic RF Injector with RF Bunch Compression fed by a Quadrupole-Free Mode Launcher	gun, cathode, electron, linac	924
	F. Toufexis, V.A. Dolgashev, C. Limborg-Deprey, S.G. Tantawi SLAC, Menlo Park, California, USA
	Funding: This project was funded by U.S. Department of Energy under Contract No. DE-AC02-76SF00515, and the National Science Foundation under Contract No. PHY-1415437. We present a design for a compact X-Band RF thermionic injector consisting of two iris-loaded accelerator structures. Both structures are fed by a single quadrupole-free TM01 mode launcher. In the first structure the electron bunches are extracted from a thermionic cathode. The second structure creates an energy chirp in the bunch for its further ballistic compression. This injector can produce short electron bunches without the need for a magnetic bunch compressor. We are developing this injector as part of a linac-based 91.392 GHz RF power source, which further comprises a booster linac and a mm-wave decelerator structure that extracts 91.392 GHz RF power from the electron beam. This source will be used to power a short-period RF undulator with 1.75 mm period. F. Toufexis and S.G. Tantawi, A 1.75 mm Period RF-Driven Undulator, these proceedings.
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MOPVA034	A Compact EUV Light Source Using a mm-Wave Undulator	electron, gun, impedance, quadrupole	928
	F. Toufexis, V.A. Dolgashev, C. Limborg-Deprey, S.G. Tantawi SLAC, Menlo Park, California, USA
	Funding: This project was funded by U.S. Department of Energy under Contract No. DE-AC02-76SF00515, and the National Science Foundation under Contract No. PHY-1415437. We are building an Extreme Ultra Violet (EUV) light source based on a 1.75 mm period RF undulator. We will use a thermionic X-Band injector which utilizes RF bunch compression. The beam is accelerated using an X-Band traveling wave accelerating structure followed by a high shunt impedance standing wave accelerating structure up to 129 MeV. The beam then goes through a 91.392 GHz RF undulator with a period of 1.75 mm, producing EUV radiation around 13.5 nm. The RF undulator is powered by a 91.392 GHz decelerating structure, which extracts the RF power from the spent electron beam. The length of the entire beam line from the cathode to the beam dump is approximately 6 m. We describe the design and projected operating parameters for this EUV light source. F. Toufexis and S.G. Tantawi, A 1.75 mm Period RF-Driven Undulator, these proceedings.
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TUXA1	Towards Diffraction Limited Storage Ring Based Light Sources	emittance, storage-ring, lattice, electron	1203
	L. Liu, H. Westfahl Jr. LNLS, Campinas, Brazil
	Experimental x-ray techniques that benefit from the great increase in brightness and coherent flux provided by the fourth generation of synchrotron light sources, based on recent advances in accelerator design and technology, are widely expanding nowadays. The basic ingredient to higher brightness is a further reduction of the electron beam emittance in storage rings dedicated to light sources. However, to fully explore the potential of these new sources, it is necessary to optimize other variables as well, such as the proper matching of electrons and photons phase-space and the possibility of using new kinds of insertion devices. Equally important is to try new ways to improve the integration between the light source capabilities and the experiment needs. In this work, recent progress of low emittance rings will be reviewed and the efforts to improve transverse coherent flux and source-to-beamline integration at the Brazilian Sirius project will be described.
	Slides TUXA1 [11.984 MB]
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TUOAA2	A Soft X-Ray Free-Electron Laser Beamline of SACLA	FEL, electron, photon, laser	1209
	K. Togawa, T. Asaka, N. Azumi, T. Hara, T. Hasegawa, N. Hosoda, T. Inagaki, T. Ishikawa, R. Kinjo, C. Kondo, H. Maesaka, S. Matsui, T. Ohshima, Y. Otake, S. Owada, H. Tanaka, T. Tanaka, M. Yabashi RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan T. Bizen, H. Kimura, S. Matsubara, K. Nakajima, T. Sakurai, T. Togashi, K. Tono JASRI/SPring-8, Hyogo, Japan T. Fukui RIKEN SPring-8 Center, Innovative Light Sources Division, Hyogo, Japan
	At the Japanese x-ray free-electron laser (FEL) facility, SACLA, the beamline-1 has been upgraded from a spontaneous radiation to a soft x-ray FEL beamline, which generates FEL lights over a wide wavelength range from the extreme-ultraviolet to the soft x-ray regions. We started operation for users in July 2016. A dedicated accelerator, which is a refinement of the SCSS test accelerator operated in 2005-2013, was installed beside the XFEL beamlines in the SACLA undulator hall. The SCSS concept to make an FEL facility compact was continuously adopted. In the 2016 summer shutdown period, the beam energy was upgraded from 500 MeV to 800 MeV by adding two C-band rf units. The maximum K-value of the undulator magnet is 2.1. The available wavelengths of the FEL lights were extended to the range from 8 to 50 nm with pulse energies between a few to few tensμJ at an operational repetition rate of 60 Hz. In this conference, we will report an overview of the upgraded SACLA-beamline-1 and characteristics of the FEL light pulse.
	Slides TUOAA2 [15.457 MB]
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TUOAA3	Progress of Pr2Fe14B Based Hybrid Cryogenic Undulators at SOLEIL	cryogenics, radiation, electron, photon	1213
	A.M. Ghaith, P. Berteaud, F. Blache, F. Briquez, N. Béchu, M.-E. Couprie, J. Da Silva Castro, J.M. Dubuisson, C. Herbeaux, C.A. Kitegi, A. Lestrade, O. Marcouillé, F. Marteau, M. Sebdaoui, G. Sharma, A. Somogyi, K.T. Tavakoli, M. Tilmont, M. Valléau SOLEIL, Gif-sur-Yvette, France C. Benabderrahmane ESRF, Grenoble, France
	Cryogenic Permanent Magnet Undulators (CPMUs) take advantage of the enhanced field performance of permanent magnets when cooled down to low temperature, enabling shorter period with sufficient magnetic field to achieve high brightness radiation in the X-ray domain. Several CPMUs have been manufactured at SOLEIL. The first CPMU of period 18 mm (U18), optimized with a phase error of 3.2° at temperature of 77 K, has been installed and operated for the past 5 years at SOLEIL for the NANOSCOPIUM beamline. We report on photon beam based alignment enabling for a better adjustment of the vertical position offset of the undulator with a precision of 50 μm, and on the correction of the taper with a precision of 5 μrad to enhance the radiation flux. A second U18 cryo-ready undulator, with a new mechanical and magnetic sorting of module shimming, has attained a phase error of 2.3° at CT without any further adjustments after the assembly. Currently, two more CPMUs are being built; a 2 m long U18 for the SOLEIL ANATOMIX beamline, and a 3 m long U15 undulator reaching a magnetic gap of 3 mm. The new challenges encountered with magnetic measurements and mechanical designs for U15 are presented.
	Slides TUOAA3 [3.491 MB]
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TUPAB026	Status of the Cryogenic Undulator CPMU-17 for EMIL at BESSY II / HZB	vacuum, Windows, permanent-magnet, feedback	1372
	J. Bahrdt, J. Bakos, W. Frentrup, S. Gottschlich, C. Kuhn, G. Pfeiffer, C. Rethfeldt, A. Rogosch-Opolka, M. Scheer, B. Schulz, L. Ziemann HZB, Berlin, Germany
	The CPMU-17 is the hard X-ray radiation source of a canted double undulator system for the Energy Materials In-situ Laboratory EMIL at BESSY II [1]. Various ambitious concepts are realized in this undulator such as Dy-hardened PrFeB-magnets, direct liquid Nitrogen cooling, dual loop feedback gap drive based on an optical micrometer and a low permeability stainless steel In-Vacuum(IV)-girder without keepers. The magnets are sorted according to Helmholtz coil and stretched wire data. Reproducibility and accuracy measurements of two IV-measurement tools needed for the CPMU-17 are presented: an IV-Hall probe bench and an IV-Moving Wire.
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TUPAB035	Field Quality of 1.5 m Long Conduction Cooled Superconducting Undulator Coils with 20 mm Period Length	multipole, photon, synchrotron, emittance	1395
	S. Casalbuoni, N. Glamann, A.W. Grau, T. Holubek, D. Saez de Jauregui KIT, Eggenstein-Leopoldshafen, Germany C. Boffo, T.A. Gerhard, M. Turenne, W. Walter Babcock Noell GmbH, Wuerzburg, Germany
	The Institute for Beam Physics and Technology (IBPT) at the Karlsruhe Institute of Technology (KIT) and the industrial partner Babcock Noell GmbH (BNG) are col-laborating since 2007 on the development of superconducting undulators both for ANKA and low emittance light sources. The first full length device with 15 mm period length has been successfully tested in the ANKA storage ring for one year. The next superconducting undulator has 20 mm period length (SCU20) and is also planned to be installed in the accelerator test facility and synchrotron light source ANKA. The SCU20 1.5 m long coils have been characterized in a conduction cooled horizontal test facility developed at KIT IBPT. Here we present the local magnetic field and field integral measurements, as well as their analysis including the expected photon spectrum. S. Casalbuoni et al., Characterization and long term operation of a novel superconducting undulator with 15 mm period length in a synchrotron light source, Phys. Rev. ST Accel. Beams, vol. 19, p.110702, Nov. 2016.
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TUPAB036	Training and Characterization of 1.5m Long Conduction Cooled Superconducting Undulator Coils with 20 mm Period Length	synchrotron, radiation, vacuum, storage-ring	1399
	A.W. Grau, S. Casalbuoni, N. Glamann, T. Holubek, D. Saez de Jauregui KIT, Eggenstein-Leopoldshafen, Germany C. Boffo, T.A. Gerhard, M. Turenne, W. Walter Babcock Noell GmbH, Wuerzburg, Germany
	The Institute for Beam Physics and Technology (IBPT) of the Karlsruhe Institute of Technology (KIT), and the company Babcock Noell GmbH (BNG) are running an R&D program on superconducting undulators (SCUs). The collaboration is working on a SCU with 20 mm period length (SCU20) for ANKA, the test facility and synchrotron radiation source, run by the IBPT. The 1.5 m long undulator coils have been tested in a conduction-cooled environment. This contribution describes the training, the stability and the thermal behavior of the coils.
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TUPAB041	Improvements in Production of Magnets and Pole Pieces for Undulators	induction, dipole, permanent-magnet, target	1415
	F.-J. Börgermann Vacuumschmelze GmbH & Co. KG, Hanau, Germany
	Permanent magnets and highly saturable pole pieces are widely used in the setup of undulators as well as dipoles, quadrupoles and sextupoles. We will present actual improvements of precision, homogeneity and basic material properties in the range of NdFeB-based permanent magnets and CoFe-based soft magnetic alloys.
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TUPAB053	Proof-of-Principle Experiment of Phase-Combined Undulator	permanent-magnet, experiment, gun, electron	1446
	R. Kinjo, T. Tanaka RIKEN SPring-8 Center, Hyogo, Japan A. Kagamihata JASRI/SPring-8, Hyogo, Japan
	A huge attractive force is the largest concern in designing a mechanical structure of undulators, in which an accurate control and high uniformity of the gap between the upper and lower magnetic girders are required. This problem is especially serious for in-vacuum undulators, in which the girders are located inside the vacuum chamber. We have proposed a new concept called a phase-combined undulator, which has intrinsically no magnetic force. In this undulator, the magnetic forces acting on the girders locally head to the longitudinal axis instead of the attractive direction, and are actually canceled out in total. Numerical calculations have shown that the attractive force will be reduced down to a negligible level. Recently, we performed a proof-of-principle experiment to examine the feasibility of this undulator concept in terms of the force between the girders and magnetic field distribution, which will be reported in the conference. R. Kinjo and T. Tanaka, Phys. Rev. ST Accel. Beams 17, 122401
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TUPAB055	Development of compact magnetic field measurement system available for in-vacuum undulators	brightness, vacuum, emittance, photon	1449
	M. Adachi, R. Kato, T. Shioya, K. Tsuchiya KEK, Ibaraki, Japan
	A low-emittance 3-GeV KEK-LS* ring has been designed at KEK. KEK-LS's undulators can produce extremely high brightness light ranging from VUV to X-ray. Brightness of undulator light strongly depends on the phase error of its periodic magnetic field. Then a precise magnetic field adjustment is required in order to prevent the reduction of the brightness performance. Generally, the adjustment is performed by the conventional field measurement system equipped with hole-probes on a huge stone table. But, for the in-vacuum undulator, the measurement must be performed without the vacuum chamber. The additional phase error caused by reattaching the chamber is not negligible for the low emittance rings. Therefore, some groups have developed measurement systems available for the direct field measurement inside the chamber,. We have started to develop a compact measurement system. Our system is compacted and stabilized by utilizing the rigid metal beam of the undulator frame instead of the stone table. In the conference, we will report the detail of the system and the present status of the development. KEK-LS HP, http://kekls.kek.jp/ T. Tanaka, et al., Physical Review ST-AB, vol.12, p.120702 (2009). * M. Musardo, et al., Proceedings of IPAC2015, Richmond, VA, USA, p.1693 (2015).
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TUPAB064	Development of a PrFeB Cryogenic Permanent Magnet Undulator (CPMU) Prototype at IHEP	vacuum, cryogenics, permanent-magnet, photon	1469
	H.H. Lu, W. Chen, L. Gong, X.Y. Li, L.Z. Li, S.C. Sun, Y.J. Sun, Y.F. Yang, L. Zhang, X.Z. Zhang, S.T. Zhao IHEP, Beijing, People's Republic of China
	A PrFeB cryogenic permanent magnet undulator (CPMU) prototype is under construction for High Energy Photon Source Test Facility (HEPS-TF) at IHEP. The device is a full scale in-vacuum undulator with a magnetic length of 2 meters and a period of 13.5 mm, and it will work at less than 85K. The whole design scheme of prototype is presented and the specifications are given, where the consideration of in-vacuum magnetic measurement bench is also included. The development progress is introduced.
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TUPAB066	Mechanical Design of a Cryogenic Permanent Magnet Undulator at IHEP	vacuum, cryogenics, permanent-magnet, photon	1475
	S.C. Sun, W. Chen, L. Gong, X.Y. Li, L.Z. Li, H.H. Lu, Y.J. Sun, Y.F. Yang, L. Zhang, X.Z. Zhang, S.T. Zhao IHEP, Beijing, People's Republic of China
	High Energy Photon Source (HEPS) at Institute of High energy Physics (IHEP) is a new 6 GeV third generation electron storage ring. Insertion devices play a significant role in achieving the high performance of the photon source. A 13.5mm period-length Cryogenic Permanent Magnet Undulator (CPMU) prototype is designed and under construction. The mechanical structure designed based on physical requirements will be presented. Work supported by Project of High Energy Photon Source Test Facility, email address: sunsc@ihep.ac.cn
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TUPAB068	Design of the CPMU Vacuum System at the HEPS	vacuum, cryogenics, radiation, photon	1482
	L. Zhang, H.H. Lu, S.C. Sun IHEP, Beijing, People's Republic of China
	The High Energy Photon Source (HEPS) is a 3rd generation synchrotron radiation light source. Its beam energy is 6 GeV and its emittance is less than 60 pm'rad, which can provide high brilliance hard X-rays to several tens of experimental stations. The Cryogenic Permanent Magnet Undulator (CPMU) is one of the key components to achieve the high brilliance. And its vacuum system is necessary to provide an ultra-high vacuum environment for CPMU operation. To design the CPMU vacuum system, we do experiments to test the outgassing rate, estimate the total gas load, calculate the effective pumping speed, design the baking program and select all pumps and other vacuum equipments. This paper presents the design specifications and the assemblage status of the CPMU vacuum system.
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TUPAB071	Experimental Results on THz Superradiation From the Undulator in Tsinghua University Beamline	radiation, electron, detector, experiment	1488
	X.L. Su, Y.-C. Du, W.-H. Huang, L. Niu, C.-X. Tang, Q.L. Tian, D. Wang, L.X. Yan TUB, Beijing, People's Republic of China Y.F. Liang Tsinghua University, Beijing, People's Republic of China
	In this paper, the first operation of a widely tunable 8-period undulator at terahertz (THz) frequency in Tsinghua University beamline was reported. Superradiate undulator radiation from sub-picosecond electron bunches compressed by chicane was observed. The measured radiation curve shows clearly that the radiation energy is proportional to the charge square, and the THz frequency can be changed from 0.4 THz to 10 THz with narrow-band spectrums. Our results demonstrate a high power and tunable coherent THz source, which could be useful for many applications in the future.
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TUPAB087	Undulator Commissioning Experience at PAL-XFEL	electron, background, radiation, site	1520
	D.E. Kim, Y.G. Jung, H.-S. Kang, I.S. Ko, H.-G. Lee, S.B. Lee, W.W. Lee, K.-H. Park, H.S. Suh PAL, Pohang, Kyungbuk, Republic of Korea I.S. Ko POSTECH, Pohang, Kyungbuk, Republic of Korea J. Pflüger XFEL. EU, Hamburg, Germany
	Pohang Accelerator Laboratory (PAL) is developing a 0.1 nm SASE based FEL based on 10 GeV S-band linear accelerator named PAL-XFEL. The hard X-ray undulator line requires 20 units of 5 m long hybrid-type conventional planar undulator while soft X-ray line requires 7 units of 5 m long hybrid type planar undulators. In this report, the final measurement results of all the undulators, phase matching scheme, and the commissioning experiences will be summarized.
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TUPAB088	Wire Position System to Consistently Measure and Record the Location Change of Girders Following Ground Changes	alignment, electron, power-supply, electronics	1523
	H. J. Choi, S.Y. Baek, H.-S. Kang, S.H. Kim, H.-G. Lee, S.B. Lee PAL, Pohang, Kyungbuk, Republic of Korea
	Several parts that comprise the large scientific device should be installed and operated at the accurate three-dimensional location coordinates where they should be subjected to survey and alignment. The location of the aligned parts should not be changed in order to ensure that the electron beam parameters of PAL-XFEL remain stable and can be operated without any problems. As time goes by, however, the ground goes through uplift and subsidence, which consequently deforms building floors. The deformation of the ground and buildings changes the location of several devices including magnets and RF accelerator tubes, which eventually leads to the alignment errors. Once alignment errors occur with regard to these parts, the electron beam deviates from its course and beam parameters change accordingly. PAL-XFEL has installed the Hydrostatic Leveling System to measure and record the vertical change of buildings and ground consistently and systematically and the Wire Position System to measure the two dimensional changes of girders. This paper is designed to introduce the operating principle and design concept of WPS and discuss the current situation regarding installation and operation.
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TUPAB104	Optimized Undulator to Generate Low Energy Photons From Medium to High Energy Accelerators	polarization, photon, optics, radiation	1556
	T.Y. Chung, M.-S. Chiu, J.C. Huang, C.-S. Hwang, J.C. Jan, C.K. Yang NSRRC, Hsinchu, Taiwan H.W. Luo NTHU, Hsinchu, Taiwan
	While emitting low energy photons from a medium or high energy storage ring, the on-axis heat load on the beam line optics can become a critical issue. In addition, the heat load in the bending magnet chamber, especially in the vertical and circular polarization mode of operation may cause some concern. In this work, we compare the heat loads for the APPLE-II and the Knot-APPLE, both optimized to emit 10 eV photons from the 3 GeV TPS. Under this constraint the heat load analysis, synchrotron radiation performance and features in various polarization modes are presented. Additional consideration is given to beam dynamics effect.
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TUPAB105	Field Measurement System for a Cryogenic Permanent Magnet Undulator in TPS	cryogenics, vacuum, permanent-magnet, multipole	1559
	C.K. Yang, C.H. Chang, T.Y. Chung, W.H. Hsieh, J.C. Huang, C.-S. Hwang NSRRC, Hsinchu, Taiwan
	Short period in-vacuum, permanent magnet undulators operating at cryogenic temperatures are being developed worldwide to serve as brilliant and coherent light sources for medium energy storage rings. A hybrid cryogenic permanent magnet undulator (CU) with PrFeB magnets has now been designed and constructed at NSRRC [1]. To characterize the performance and to determine magnetic field errors after cool down poses some technical chal-lenges compared to room temperature undulators. A new system combining a Hall probe and a stretched wire has been designed to measure the field integrals, trajectory, phase errors, and K value under low temperature and vacuum conditions. Field measurements in this cryogenic undulator will be performed around 77 K as well as at room temperature, making temperature dependent calibra-tion of the Hall probes necessary. The main features and improvement of the measurement and calibration system are presented.
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TUPAB106	Development of a Cryogenic Permanent Magnet Undulator for the TPS	vacuum, permanent-magnet, cryogenics, radiation	1562
	J.C. Huang, C.H. Chang, T.Y. Chung, C.-S. Hwang, J.C. Jan, C.S. Yang, C.K. Yang NSRRC, Hsinchu, Taiwan H. Kitamura RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
	Development of a cryogenic permanent magnet undu-lator (CPMU) at the Taiwan Photon Source (TPS) is the most recent activity toward a new light source for the Phase-II beamlines. A hybrid-type CPMU with a period length of 15 mm is under construction with PrFeB permanent-magnet materials. A maximum effective magnetic field of 1.77 T at a gap of 3 mm is expected when the magnets (PMs) are cooled down around 77 K. The features desired for the TPS CPMU are low-intrinsic-phase-error characteristics and high thermal budget for various kinds of heat loads. The design of the TPS CPMU is discussed in this paper.
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TUPAB114	Design Study for a Plasma Undulator Experiment Using Capillary Based Discharge Plasma Source	laser, plasma, electron, experiment	1584
	O. Mete Apsimon, R. Apsimon, Y. Ma, D. Seipt, M.J.V. Streeter, A.G.R. Thomas Cockcroft Institute, Lancaster University, Lancaster, United Kingdom T.H. Pacey, G.X. Xia UMAN, Manchester, United Kingdom
	A plasma undulator is formed when a short laser pulse is injected into plasma off-axis or at an angle that causes the centroid of this laser pulse to oscillate. Ponderomotively driven plasma wake will follow this centroid given that the product of the plasma wave number and the characteristic Rayleigh length of the laser is much larger than one. This oscillating transverse wakefield may work as an undulator forcing particles to follow sinusoidal trajectories and emit synchrotron radiation. In this paper, plans for an experiment are introduced and resulting radiation and injected beam characteristics are discussed. The aforementioned laser centroid oscillations are demonstrated using, EPOCH, a PIC code for laser-plasma interactions.
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TUPAB116	Insertion Devices at Diamond Light Source: A Retrospective Plus Future Developments	wiggler, storage-ring, insertion-device, insertion	1592
	Z. Patel, A. George, S. Milward, E.C.M. Rial, A.J. Rose, R.P. Walker, J.H. Williams DLS, Oxfordshire, United Kingdom
	2017 marks the tenth year of Diamond operation, during which time all insertion device straights have been filled. Diamond Light Source is a third generation, 3 GeV facility that boasts 29 installed insertion devices. Most room temperature devices have been designed, manufactured and measured in-house, and progress has been made in structure design and control systems to ensure new devices continue to meet stringent requirements placed upon them. The ‘completion' of the storage ring is not, however, the end of activity for the ID group at Diamond, as beamlines map out potential upgrade paths to Cryogenic Permanent Magnet Undulators (CPMUs) and SuperConducting Undulators (SCUs). This paper traces the progress of ID design at Diamond, and maps out future projects such as the upgrade to CPMUs and the challenges of designing a fixed-gap mini-wiggler to replace a sextupole in the main storage ring lattice.
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TUPAB117	Conceptual Design of a Novel SCAPE Undulator	photon, simulation, lattice, vacuum	1596
	Y. Ivanyushenkov, J.F. Fuerst, E. Gluskin, Q.B. Hasse, M. Kasa, Y. Shiroyanagi, E. Trakhtenberg ANL, Argonne, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357. A concept of a novel SuperConducting Arbitrarily Polarizing Emitter, or SCAPE, has recently been suggested at the Advanced Photon Source. It consists of two pairs - both vertical and horizontal - of superconducting planar magnets assembled around a beam vacuum chamber. Such a device will be capable of generating either planar or circularly polarized photons, depending on which pair of magnets is energized. The magnetic simulation suggests that due to the employment of superconducting technology, the expected magnetic field is higher than that of the APPLE undulators. The SCAPE undulators could be useful for the fourth generation of storage rings with a multi-bend achromat lattice, as well as for the FELs where utilization of round beam vacuum chambers becomes possible. The results of magnetic modelling, as well as the design concept of the SCAPE, are presented.
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TUPAB122	Engineering Optimization of The Support Structure and Drive System for the LCLS-II Soft X-Ray Undulator Segments	photon, simulation, experiment, laser	1602
	A.J. DeMello, D. Arbelaez, D. Bianculli, A.P. Brown, J.N. Corlett, J.R. Dougherty, D.E. Humphries, J.-Y. Jung, M. Leitner, S. Marks, K.A. McCombs, K.L. Ray, D.A. Sadlier, D. Schlueter, E.J. Wallén LBNL, Berkeley, California, USA
	Funding: Work supported by the Director, O'ce of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. The Linear Coherent Light Source II (LCLS-II) project, an upgrade to the free-electron laser facility at SLAC, is replacing the undulator system from a fixed gap to a variable gap system to enable tuning of the photon energy range. The LCLS-II project will include a soft x-ray (SXR) beam line and a hard x-ray (HXR) beam line. The SXR undulators are conventional vertical-gap horizontally-polarizing devices while the HXR undulators are novel horizontal-gap vertically-polarizing devices. This paper describes in detail the development of the SXR mechanical support structure and drive system. The effort has included extensive analysis of the various components to ensure that the undulators will perform within the design specifications. Engineering simulations undertaken and experiments performed to validate the computer modeling are presented together with measurement results from prototype and pre-production undulators.
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TUPAB123	Hard X-Ray and Soft X-Ray Undulator Segments for the Linear Coherent Light Source Upgrade (LCLS-II) Project	linac, photon, FEL, electron	1605
	M. Leitner, D. Arbelaez, A.J. Band, D. Bianculli, A.P. Brown, J.N. Corlett, A.J. DeMello, J.R. Dougherty, L. Garcia Fajardo, K. Hanzel, M. Hoyt, D.E. Humphries, D. Jacobs, C. Joiner, J.-Y. Jung, D. Leitner, S. Marks, K.A. McCombs, D.V. Munson, K.L. Ray, D.A. Sadlier, J.J. Savino, D. Schlueter, E.J. Wallén, V. Waring, A. Zikmund LBNL, Berkeley, California, USA C.J. Andrews, D.E. Bruch, A.L. Callen, G. Janša, S. Jansson, K.R. Lauer, Yu.I. Levashov, D.S. Martinez-Galarce, B.D. McKee, H.-D. Nuhn, Â. Oven, M. Rowen, Z.R. Wolf SLAC, Menlo Park, California, USA
	Funding: Work supported by the Director Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Stanford Linear Accelerator Laboratory is currently constructing the Linear Coherent Light Source II (LCLS-II), a free-electron laser (FEL) which will deliver x-rays at an energy range between 0.2 keV and 5 keV at high repetition rate of up to ~1 MHz using a new 4 GeV superconducting RF linac, and at and an energy range between 1 keV and 25 keV when driven by an existing copper linac at up to 120 Hz repetition rate. To cover the full photon energy range, LCLS-II includes two variable-gap, hybrid-permanent-magnet undulator lines: A soft x-ray undulator (SXR) line with 21 undulator segments optimized for a photon energy range from 0.2 keV to 1.3 keV plus a hard x-ray undulator (HXR) line with 32 undulator segments designed for a photon energy range from 1.0 keV to 25.0 keV. Lawrence Berkeley National Laboratory is responsible for fabricating the 53 undulator segments. This paper summarizes the main parameters and design attributes for both LCLS-II undulator segment types.
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TUPAB124	Development of the Manufacturing and QA Processes for the Magnetic Modules of the LCLS-II Soft X-Ray Undulators	simulation, status, laser, free-electron-laser	1609
	K.L. Ray, D. Arbelaez, A.J. Band, D. Bianculli, A.P. Brown, J.N. Corlett, A.J. DeMello, J.R. Dougherty, L. Garcia Fajardo, K. Hanzel, D.E. Humphries, J.-Y. Jung, D. Leitner, M. Leitner, S. Marks, K.A. McCombs, D.V. Munson, D.A. Sadlier, D. Schlueter, E.J. Wallén, V. Waring, A. Zikmund LBNL, Berkeley, California, USA D.E. Bruch, A.L. Callen, G. Janša, D.S. Martinez-Galarce, H.-D. Nuhn, E. Ortiz, Â. Oven, M. Rowen, Z.R. Wolf SLAC, Menlo Park, California, USA
	Funding: Work supported by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. A new free electron laser being built at SLAC National Accelerator Laboratory, the Linear Coherent Light Source II (LCLS-II), will use 21 soft x-ray undulators (SXR) and 32 hard x-ray undulators (HGVPU). Lawrence Berkeley National Laboratory (LBNL) is responsible for the design and manufacturing of all variable-gap, hybrid permanent-magnet undulators. The physics requirements for the undulators specify a longitudinal pole misalignment maximum rms error of 25 μm and a vertical pole misalignment maximum error of 50 μm. In addition, magnet positioning critically influences the gap-dependent field properties due to saturation effects at the smallest operational gaps. This paper discusses the manufacturing and QA methods developed to carefully control the longitudinal and vertical pole and magnet positions during undulator production. Inspection results are discussed based on data gathered during construction of a prototype as well as pre-production soft x-ray undulator.
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TUPAB125	Magnetic Field Measurements at LBNL on Soft X-Ray and Hard X-Ray Undulator Segments for the Linear Coherent Light Source Upgrade (LCLS-II) Project	photon, linac, software, alignment	1612
	E.J. Wallén, D. Arbelaez, J.N. Corlett, L. Fajrado, H.W. Kim, M. Leitner, S. Marks, D. Schlueter, A. Zikmund LBNL, Berkeley, California, USA Yu.I. Levashov, H.-D. Nuhn, Z.R. Wolf SLAC, Menlo Park, California, USA
	Funding: Work supported by the Director, O'ce of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Stanford Linear Accelerator Laboratory is currently constructing the Linear Coherent Light Source II (LCLS-II), a FEL which will deliver x-rays at an energy range 0.2-5 keV at high repetition rate of up to 1 MHz using a new 4 GeV superconducting linac, and at an energy range 1-25 keV when using the existing copper linac at up to 120 Hz. To cover the full photon energy range, LCLS-II includes two variable-gap, hybrid-type permanent magnet undulator lines: A soft x-ray undulator (SXR) line with 21 undulator segments for the photon energy range 0.2-1.3 keV plus a hard x-ray undulator (HXR) line with 32 undulator segments designed for a photon energy range from 1-5 keV when using the superconducting linac. The HXR line is also designed to support 25 keV and higher photon energies when using the existing copper linac. Lawrence Berkeley National Laboratory (LBNL) is responsible for fabricating the undulators and tuning 23 of the HXR undulators. This paper summarizes the magnetic field measurements carried out on the pre-production undulators and describes the plans at LBNL for the magnetic measurements on the HXR undulators in series production.
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TUPAB133	Perturbation Analysis for Beam Trajectories. Determining Local Shielding Containment for LCLS-II	shielding, quadrupole, simulation, dipole	1637
	M. Santana-Leitner SLAC, Menlo Park, California, USA
	Funding: Work supported by U.S. Department of Energy contract DE-AC02-76SF00515 Containment of beam losses by halo and momentum/energy collimators is a well-established practice for normal operation of particle accelerators where tracking codes are applied. However, for exceptional events, such as magnet power failures, severe lattice mis-match, etc., ad-hoc analytical approaches are typically applied. Oftentimes those simplified methods are not automatic; they don't define the full phase-space of mis-steered trajectories and cannot keep up with beam-line upgrades. Moreover, there may exist a disconnect between the teams analyzing consequences of errant beams and those involved in beam-line design. With electron beams exceeding 100 kW, design of LCLS-II at SLAC National Accelerator Laboratory required exhaustive beam-containment studies to avoid potential destruction of components and excessive dose rates. The geometry of the different beam-lines and the nominal optics was built with MadFLUKA [1], and FLUKA [2] Monte Carlo code along with perturbations to magnetic fields was used to inspect failures compatible with beam operations and hardware settings. Consequences of mis-steered rays and the respective mitigations were directly analyzed with FLUKA. [1] M. Santana-Leitner et al., MadFLUKA Beam Line 3D Builder. Simulation of Beam Loss Propagation in Accelerators, IPAC14 proceedings, MOPME040 [2] A. Ferrari et al, The FLUKA Code: Developments and Challenges for High Energy and Medical Applications, Nuclear Data Sheets 120, 211-214 (2014)
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TUPAB134	Life Expectancy Studies for LCLS-II Permanent Magnet Undulators	radiation, permanent-magnet, electron, optics	1640
	M. Santana-Leitner, D.E. Bruch, R.C. Field, D.S. Martinez-Galarce, B.D. McKee, H.-D. Nuhn, M. Rowen, S.W. Score SLAC, Menlo Park, California, USA
	Funding: Work supported by U.S. Department of Energy contract DE-AC02-76SF00515 LCLSII at SLAC National Accelerator Laboratory will add a 4 GeV superconducting Linac to the existing 20 GeV Cu structure. Electron beams from the two sources going through two new variable gap undulators [] will produce FEL ranging 200-5000 keV at up to 929 kHz, also reaching 20 keV at low frequency. Such performance will be achieved by hybrid design undulators with NdFeB magnet blocks until radiation-induced demagnetization exceeds 0.01%. This is a sizable challenge, as LCLS-II will carry 120 kW beams in both its soft (SXR) and hard (HXR) beam-lines. Even small fractional losses could result excessive if too frequent or not detected and aborted fast enough. A model of SXR undulator was set for FLUKA [] radiation transport, including segments, phase-shifters, quadrupoles, RFBPM, stands/pillars and interconnecting parts. Components were installed according to MAD files, which were also used to code the optics. Beam-loss/shower propagation was simulated for beam mis-steering, interception at wire scanners and gas-bremsstrahlung interactions. Results help set limits on shut-off times, uniform loss levels and wire scanner use, and to define placement for beam loss monitors. M. Leitner et al, Hard X-Ray and Soft X-Ray Undulator Segments for the Linear Coherent Light Source Upgrade (LCLS-II) Project, these proceedings ** A. Ferrari et al, The FLUKA Code: Developments and Challenges for High Energy and Medical Applications, Nuclear Data Sheets 120, 211-214 (2014)
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TUPAB135	A 1.75 mm Period RF-Driven Undulator	laser, electron, FEL, cavity	1643
	F. Toufexis, S.G. Tantawi SLAC, Menlo Park, California, USA
	Funding: This project was funded by U.S. Department of Energy under Contract No. DE-AC02-76SF00515, and the National Science Foundation under Contract No. PHY-1415437. To reduce the linac energy, and hence the size required for a Free Electron Laser radiating at a given wavelength, a smaller undulator period with sufficient field strength is needed. Previous work from our group successfully demonstrated a microwave undulator at 11.424 GHz using a corrugated cylindrical waveguide operating in the HE11 mode. Scaling down the undulator period using this technology poses the challenge of confining and coupling* the electromagnetic fields while maintaining over-moded features for power handling capability and electron beam wakefield mitigation. In this work, we present a novel end section of an RF undulator at 91.392 GHz. To confine the fields inside the undulator, a corrugated waveguide is connected through a matching section to a linear taper and a mirror. After the mirror, a Bragg reflector and a matching section are used to reflect back all the fields leaking out of the mirror opening. * F. Toufexis, J. Neilson, and S.G. Tantawi, Coupling and Polarization Control in a mm-wave Undulator, these proceedings.
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TUPAB136	Coupling and Polarization Control in a mm-wave Undulator	polarization, coupling, controls, electron	1647
	F. Toufexis, J. Neilson, S.G. Tantawi SLAC, Menlo Park, California, USA
	Funding: This project was funded by U.S. Department of Energy under Contract No. DE-AC02-76SF00515, and the National Science Foundation under Contract No. PHY-1415437. To reduce the linac energy required for an FEL radiating at a given wavelength, and hence its size, a smaller undulator period with sufficient field strength is needed. Previous work from our group successfully demonstrated a microwave undulator at 11.424 GHz using a corrugated cylindrical waveguide operating in the HE11 mode. Scaling down the undulator period using this technology poses the challenge of confining and coupling the electromagnetic fields while maintaining overmoded features for power handling capability and electron beam wakefield mitigation. We have designed a mm-wave undulator cavity at 91.392 GHz. This undulator requires approximately 1.4 MW for sub-microsecond pulses to generate an equivalent K value of 0.1. Transferring such amounts of power in mm-wave frequencies requires overmoded corrugated waveguides, and coupling through irises creates excessive pulsed heating. We have designed a novel mode launcher that allows coupling power from a highly overmoded corrugated waveguide to the undulator through the beam pipe. Additionally, this mode launcher can be used along with grating polarizers to control the polarization of the produced light. F. Toufexis and S.G. Tantawi, A 1.75 mm Period RF-Driven Undulator, these proceedings.
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TUPAB140	Analysis and Correction of in-Vacuum Undulator Misalignment Effects in a Storage Ring Synchrotron Radiation Source	electron, alignment, radiation, storage-ring	1663
	O.V. Chubar, T.A. Caswell, Y. Chen-Wiegart, A. Fluerasu, Y. Hidaka, D.A. Hidas, C.A. Kitegi, M.S. Rakitin, T. Tanabe, J. Thieme, L. Wiegart, G. Williams BNL, Upton, Long Island, New York, USA
	Funding: Work was partially supported by US DOE SBIR grants DE-SC0006284 and DE-SC0011237. In-vacuum undulators (IVU) are currently very extensively used at different light source facilities, and in particular in medium-energy storage rings, for the production of high-brightness and high-flux hard X-rays. The relatively small (~5 mm or less) vertical magnetic gaps used in these planar undulators make them, however, rather sensitive to the accuracy of alignment of magnet arrays with respect to electron orbit in the vertical plane. Based on results of commissioning of a number of IVUs at hard X-ray beamlines of NSLS-II, their eventual misalignment with respect to the electron orbit was found to be among frequent reasons of spectral underperformance of the beamlines. We will present results of simulations of different IVU misalignment effects on magnetic fields seen by electron beam and on the emitted undulator radiation spectra. The simulations show e.g. that an impact of angular misalignment of an IVU on the radiation spectrum can be minimized if the IVU elevation is selected to make the electron orbit to pass through the IVU magnetic center. Experimental results of spectrum-based alignment of IVUs at hard X-ray beamlines will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB140
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TUPAB146	Vibration Measurements of Super-Conducting Undulator at SSRF	data-analysis, data-acquisition, experiment, damping	1675
	R.B. Deng, Y. Liu, L. Wang, S. Xiang SINAP, Shanghai, People's Republic of China
	Funding: Work supported by the National Natural Science Foundation of China (Grant No. 11405255) A Super-Conducting Undulator (SCU) is being built at SSRF. Mechanical stability of SCU is critical to beam stability since the central load is supported by special strings in SCU and the vibration of load will cause directly the vibration of beam. In this paper, vibration results of several key components including central load, cold head, frame support, etc, are studied under different working mode of compressors. The ground vibrations at different distances are compared to get the influence of compressors to SCU. Useful suggestions and possible measures are described to mitigate the vibration and improve SCU stability.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB146
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TUPIK003	Electron Transport on COXINEL Beam Line	electron, laser, free-electron-laser, FEL	1688
	T. André, I.A. Andriyash, F. Blache, F. Bouvet, F. Briquez, M.-E. Couprie, Y. Dietrich, J.P. Duval, M. El Ajjouri, A.M. Ghaith, C. Herbeaux, N. Hubert, M. Khojoyan, M. Labat, N. Leclercq, A. Lestrade, A. Loulergue, O. Marcouillé, F. Marteau, P. N'gotta, P. Rommeluère, K.T. Tavakoli, M. Valléau SOLEIL, Gif-sur-Yvette, France S. Bielawski, C. Evain, C. Szwaj PhLAM/CERLA, Villeneuve d'Ascq, France S. Corde, J. Gautier, J.-P. Goddet, G. Lambert, B. Mahieu, V. Malka, S. Smartzev, C. Thaury LOA, Palaiseau, France E. Roussel Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	COXINEL experiment aims at demonstrating free electron laser (FEL) amplification with a laser plasma accelerator (LPA). For COXINEL, a dedicated 8 m transport line has been designed and prepared at SOLEIL. We present here LPA beam transport results around 180 MeV through this line. Different electron beam optics were applied.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK003
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TUPIK106	Analysis of the Synchrotron Radiation from Segmented Undulator in Double-Mini Beta Function	radiation, brilliance, electron, photon	1964
	H.W. Luo, C.H. Lee NTHU, Hsinchu, Taiwan T.Y. Chung, C.-S. Hwang NSRRC, Hsinchu, Taiwan C.-S. Hwang NCTU, Hsinchu, Taiwan
	Three long straight sections with double-mini beta-y lattice were created in the Taiwan Photon Source (TPS) for which the effects of focusing elements and phase shifters between the collinear undulators result in incorrect calculations of the brilliance while assuming a Gaussian-approximation. Therefore, an on-axis Wigner distribution function (WDF), which includes effects of wave phenomena, is a natural way to measure the intensity of synchrotron radiation and is used in this article as the definition of brilliance.
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TUPIK108	Beam Based Alignment Studies for the CLARA FEL Test Facility	FEL, quadrupole, alignment, cavity	1971
	J.K. Jones, N. Thompson STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	The CLARA (Compact Linear Accelerator for Research and Applications) test facility is designed to experimentally demonstrate innovative FEL schemes for future light source applications. Such schemes can place strict requirements on the accelerator beam properties as well as the relative alignment of the beam in the FEL radiators and modulators. Beam-based alignment (BBA) of the FEL section is therefore an operational requirement for all advanced FEL facilities. In this paper we demonstrate results of CLARA BBA simulations, and also report initial simulation results from the use of non-linear algorithms to optimise the FEL performance directly.
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WEOCA3	Status of the Development of Superconducting Undulators at the Advanced Photon Source	photon, vacuum, FEL, storage-ring	2499
	Y. Ivanyushenkov, C.L. Doose, J.F. Fuerst, E. Gluskin, Q.B. Hasse, M. Kasa, Y. Shiroyanagi ANL, Argonne, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357 Superconducting planar undulator (SCU) technology has been developed and is currently in use at the Advanced Photon Source (APS). The experience of building and operating the first short-length, 16-mm period superconducting undulator, SCU0, paved the way for two 1-m long, 18-mm period devices, SCU18-1 and SCU18-2. The first of those undulators has been in operation since May 2015, while the second one replaced SCU0 in September 2016. The possibility of building planar SCUs with a high quality field has been demonstrated at the APS. The measured phase errors of SCU18-2 at the design operational current are only 2 degrees rms, for example. An FEL SCU prototype - a 1.5-m long, 21-mm period undulator - was also built and tested as part of an LCLS SCU R&D program. This undulator successfully achieved all LCLS-II undulator requirements including a phase error of 5 degrees rms. The superconducting undulator technology also allows the fabrication of circular polarizing devices. Currently, a new helical SCU is under construction at the APS. In addition, the concept of a novel Superconducting Arbitrarily Polarizing Emitter, or SCAPE, has been suggested and is now under development.
	Slides WEOCA3 [2.826 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEOCA3
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WEPAB001	Parallel Operation of SASE1 and SASE3 Undulator Sections of European XFEL	radiation, simulation, kicker, operation	2554
	A. Sargsyan, V. Sahakyan CANDLE SRI, Yerevan, Armenia W. Decking DESY, Hamburg, Germany
	In the current paper the numerical simulation results for parallel (decoupled) operation of SASE1 and SASE3 undulator sections of European XFEL are presented. The study was based on the idea of betatron switcher imple-mentation. It was shown that it is possible to avoid energy spread growth in SASE1 and to reach the saturation in SASE3 in desirable range of radiation wavelengths by a trajectory kick before SASE1 and its correction before SASE3.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB001
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WEPAB004	Progress Status for the 10 Year Old SOLEIL Synchrotron Radiation Facility	operation, injection, storage-ring, booster	2564
	L.S. Nadolski, Y.-M. Abiven, P. Brunelle, A. Buteau, N. Béchu, M.-E. Couprie, X. Delétoille, J.M. Dubuisson, C. Herbeaux, N. Hubert, M. Labat, J.-F. Lamarre, P. Lebasque, A. Lestrade, A. Loulergue, M. Louvet, P. Marchand, O. Marcouillé, F. Marteau, A. Nadji, R. Nagaoka, F. Ribeiro, K.T. Tavakoli, M.-A. Tordeux SOLEIL, Gif-sur-Yvette, France
	Synchrotron SOLEIL has just turned 10 years since its commissioning. The 2.75 GeV facility is now delivering very stable photon beams to 29 beam lines. A total of 5 operation modes are available in top-up. Maintaining and updating the key performance metric remains a daily work facing both aging of components and tighter operation requirements. Low-alpha operation is attracting more beam lines leading us to an upgrade of the Booster (BOO) radiofrequency (RF) system in order to increase the injection efficiency into the storage ring (SR). The femtoslicing experiment is now in production for a hard X-ray beam line; a dedicated chicane has been installed for a second beam line in the soft X-ray regime. The two long canted beam lines can operate simultaneously at minimum gaps since May 2016 thanks to the introduction of a dedicated photon absorber and a fast angle interlock. R&D work in several areas will be reported. In parallel lattice design are in progress both for short term and long term evolution of the ring performance.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB004
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WEPAB009	Pilot Experiments and New Developments at the DELTA Short-Pulse Facility	laser, electron, radiation, experiment	2578
	S. Khan, B. Büsing, F. Götz, M.A. Jebramcik, N.M. Lockmann, C. Mai, A. Meyer auf der Heide, R. Niemczyk, B. Riemann, G. Shayeganrad, M. Suski, P. Ungelenk, D. Zimmermann DELTA, Dortmund, Germany U. Bovensiepen, S. Döring, A. Eschenlohr, M. Ligges, L. Plucinski, M. Plötzing, C.M. Schneider, S. Xiao Universität Duisburg-Essen, Duisburg, Germany S. Cramm Forschungszentrum Jülich, Peter-Gruenberg-Institut-6, Jülich, Germany M. Gehlmann Forschungszentrum Jülich, Peter Gruenberg Institut, Jülich, Germany
	Funding: BMBF 05K16PEA, BMBF 05K16PEB, Mercur Pr-2014-0047 At the 1.5-GeV synchrotron light source DELTA operated by the TU Dortmund University, ultrashort radiation pulses in the vacuum ultraviolet (VUV) and terahertz (THz) regime are routinely generated by the interaction of electron bunches with femtosecond laser pulses. A laser-induced energy modulation is converted into a density modulation (microbunching) by a magnetic chicane, leading to coherent emission at harmonics of the initial laser wavelength (coherent harmonic generation, CHG). Path length differences of the energy-modulated electrons along the magnetic lattice lead to a dip in the longitudinal charge distribution, which gives rise to the coherent emission of THz radiation. In first pump-probe photoemission experiments, the spatial and temporal overlap of laser pump and CHG probe pulse on the sample was demonstrated. Furthermore, the effect of two temporally separated seed pulses was studied in the VUV and (sub-)THz regime.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB009
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WEPAB010	Progress Towards an EEHG-Based Short-Pulse Source at DELTA	electron, laser, radiation, synchrotron	2582
	A. Meyer auf der Heide, F.H. Bahnsen, B. Büsing, F. Götz, S. Hilbrich, M.A. Jebramcik, S. Khan, N.M. Lockmann, C. Mai, R. Niemczyk, B. Riemann, G. Shayeganrad, M. Suski, P. Ungelenk, D. Zimmermann DELTA, Dortmund, Germany
	Funding: Work supported by the accelerator initiative (ARD) of the Helmholtz society, BMBF 05K13PE3, BMBF 05K16PEA. The short-pulse source at the 1.5-GeV synchrotron light source DELTA, operated by the TU Dortmund University, enables the generation of sub-ps radiation pulses in the VUV regime based on coherent harmonic generation (CHG). As an upgrade, the employment of echo-enabled harmonic generation (EEHG) is planned which allows to produce shorter wavelengths. Recent developments and measurements regarding the twofold energy modulation required for EEHG are presented.
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WEPAB017	Generation of Ultra-Short Electron Bunches and FEL Pulses and Characterization of Their Longitudinal Properties at FLASH2	electron, FEL, operation, laser	2600
	F. Christie, J. Rönsch-Schulenburg, S. Schreiber, M. Vogt DESY, Hamburg, Germany
	The free-electron laser in Hamburg (FLASH) is a user facility, delivering soft X-ray radiation, consisting of two beam lines, FLASH1 and FLASH2. The injector and the main linac are shared between both beam lines. Starting in 2014, FLASH2 has been commissioned for user operation. Currently, there is no hardware installed for the direct measurement of the electron bunch length nor the photon pulse duration at FLASH2. Exact knowledge of the pulse duration is essential for time-resolved user experiments performed at FLASH. Therefore, we are designing a modified beam line, containing a new type of X-band deflecting cavity* and a dipole, downstream of the FLASH2 undulator, to map the longitudinal phase space onto a beam screen. Anticipating the feasibility of measuring the longitudinal phase space with high resolution, a study on optimizing the free-electron laser (FEL) performance for shortest bunches is ongoing. *B. Marchetti et al., X-Band TDS project, contribution to these conference proceedings
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB017
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WEPAB019	Concept for a Seeded FEL at FLASH2	FEL, electron, laser, free-electron-laser	2607
	C. Lechner, R.W. Aßmann, J. Bödewadt, M. Dohlus, N. Ekanayake, B. Faatz, G. Feng, I. Hartl, T. Laarmann, T. Lang, L. Winkelmann, I. Zagorodnov DESY, Hamburg, Germany A. Azima, M. Drescher, Th. Maltezopoulos, T. Plath, J. Roßbach, W. Wurth University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany S. Khan DELTA, Dortmund, Germany
	The free-electron laser (FEL) FLASH is a user facility delivering photon pulses down to 4 nm wavelength. Recently, the second FEL undulator beamline 'FLASH2' was added to the facility. Operating in self-amplified spontaneous emission (SASE) mode, the exponential amplification process is initiated by shot noise of the electron bunch, resulting in photon pulses of limited temporal coherence. In seeded FELs, the FEL process is initiated by coherent seed radiation, improving the longitudinal coherence of the generated photon pulses. The conceptual design of a possible seeding option for the FLASH2 beamline foresees the installation of the hardware needed for high-gain harmonic generation (HGHG) seeding upstream of the already existing undulator system. In this contribution, we present the beamline design and numerical simulations of the seeded FEL.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB019
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WEPAB020	Beam Loss Simulations for the Implementation of the Hard X-Ray Self-Seeding System at European XFEL	electron, simulation, collimation, neutron	2611
	S. Liu, W. Decking, L. Fröhlich DESY, Hamburg, Germany
	The European XFEL is designed to be operated with a nominal beam energy of 17.5 GeV at a maximum repetition rate of 27000 bunches/second. The high repetition rate together with the high loss sensitivity of the undulators raises serious radiation damage concern, especially for the implementation of the Hard X-ray Self-Seeding (HXRSS) system, where a 100 um thick diamond crystal will be inserted close to the beam in the undulator section. Since the seeding power level highly depends on the delay of the electron beam with respect to the photon beam, it is crucial to define the minimum electron beam offset to the edge of the crystal in the HXRSS chicane. At European XFEL a ~200 m long post-linac collimation section has been designed to protect the undulators. In the HXRSS scheme, however, beam halo hitting the crystal can generate additional radiation. Particle tracking simulations have been performed using GEANT4 and BDSIM for the undulator and the collimation section, respectively. The critical number of electrons allowed to hit the crystal is estimated for a certain operation mode and the efficiency of beam halo collimation is investigated to predict the minimum HXRSS chicane delay.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB020
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WEPAB021	Experience with Multi-Beam and Multi-Beamline FEL-Operation	laser, experiment, operation, FEL	2615
	J. Rönsch-Schulenburg, B. Faatz, K. Honkavaara, M. Kuhlmann, S. Schreiber, R. Treusch, M. Vogt DESY, Hamburg, Germany
	DESY's free-electron laser FLASH provides soft X-ray pulses for scientific users at wavelengths down to 4 nm simultaneously in two undulator beamlines. They are driven by a common linear superconducting accelerator with a beam energy of up to 1.25 GeV. The superconducting technology allows the acceleration of electron bunch trains of several hundred bunches with a spacing of 1 microsecond or more and a repetition rate of 10 Hz. A fast kicker-septum system directs one part of the bunch train to FLASH1 and the other part to FLASH2 keeping the full 10 Hz repetition rate for both. The unique setup of FLASH allows independent FEL pulse parameters for both beamlines. In April 2016, simultaneous operation of FLASH1 and FLASH2 for external users started. This paper reports on our operating experience with this type of multi-beam, multi-beamline set-up.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB021
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WEPAB022	Background-free Harmonic Production in XFELs via a Reverse Undulator Taper	FEL, background, radiation, electron	2618
	E. Schneidmiller, M.V. Yurkov DESY, Hamburg, Germany
	Nonlinear harmonics in X-ray FELs can be parasitically produced as soon as FEL reaches saturation, or can be radiated in dedicated afterburners. In both cases there is a strong background at the fundamental, since it is much stronger than harmonics. One can get around this problem by application of the recently proposed reverse undulator tapering. In this contribution we present numerical simulations of harmonic production in such a configuration as well as recent results from FLASH where the second and the third harmonics were efficiently generated with a low background at the fundamental. We also present the results for a high-contrast operation when the afterburner is tuned to the fundamental.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB022
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WEPAB023	First Operation of a Harmonic Lasing Self-Seeded FEL	FEL, electron, operation, brightness	2621
	E. Schneidmiller, B. Faatz, M. Kuhlmann, J. Rönsch-Schulenburg, S. Schreiber, M. Tischer, M.V. Yurkov DESY, Hamburg, Germany
	Harmonic lasing is a perspective mode of operation of X-ray FEL user facilities that allows to provide brilliant beams of higher energy photons for user experiments. Another useful application of harmonic lasing is so called Harmonic Lasing Self-Seeded Free Electron Laser (HLSS FEL) that allows to improve spectral brightness of these facilities. In the past, harmonic lasing has been demonstrated in the FEL oscillators in infrared and visible wavelength ranges, but not in high-gain FELs and not at short wavelengths. In this paper we report on the first evidence of the harmonic lasing and the first operation of the HLSS FEL at the soft X-ray FEL user facility FLASH in the wavelength range between 4.5 nm and 15 nm. Spectral brightness was improved in comparison with Self-Amplified Spontaneous emission (SASE) FEL by a factor of six in the exponential gain regime. A better performance of HLSS FEL with respect to SASE FEL in the post-saturation regime with a tapered undulator was observed as well. The first demonstration of harmonic lasing in a high-gain FEL and at a short wavelength paves the way for a variety of applications of this new operation mode in X-ray FELs.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB023
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WEPAB024	Commissioning and First Heating with the European XFEL Laser Heater	laser, electron, cathode, FEL	2625
	M. Hamberg Uppsala University, Uppsala, Sweden F. Brinker, M. Scholz DESY, Hamburg, Germany
	Funding: We thank DESY and Swedish research council under Project number DNR-828-2008-1093 for financial support. The Laser Heater of the European XFEL has been installed and commissioning is in progress. We discuss the setup and the results of the first electron beam heating in the injector section.
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WEPAB027	Frequency Doubler and Two-color Mode of Operation at Free Electron Laser FLASH2	radiation, electron, operation, FEL	2635
	M. Kuhlmann, E. Schneidmiller, M.V. Yurkov DESY, Hamburg, Germany
	We report on the results of the first operation of a frequency doubler at free electron laser FLASH2. The scheme uses the feature of the variable gap undulator. Undulator is divided in two parts. The second part of the undulator is tuned to the double frequency of the first part. Amplification process in the first undulator part is stopped at the onset of the nonlinear regime, such that nonlinear higher harmonic bunching in the electron beam density becomes pronouncing, but the radiation level is still small to disturb the electron beam significantly. Modulated electron beam enters the second part of the undulator and generates radiation at the 2nd harmonic. Frequency doubler allows operation in a two-color mode and operation at shorter wavelengths with respect to standard SASE scheme. Tuning of the electron beam trajectory, phase shifters and compression allows to tune intensities of the first and the second harmonic. The shortest wavelength of 3.1 nm (photon energy 400 eV) has been achieved with frequency doubler scheme, which is significantly below the design value for the standard SASE option.
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WEPAB029	Optimum Undulator Tapering of SASE FEL: From the Theory to Experiment	electron, FEL, radiation, laser	2639
	E. Schneidmiller, M.V. Yurkov DESY, Hamburg, Germany
	Optimization of the amplification process in FEL amplifier with diffraction effects taken into account results in a specific law of the undulator tapering []. It is a smooth function with quadratic behavior in the beginning of the tapering section which transforms to a linear behavior for a long undulator. In practice, undulator consists of a sequence of modules of fixed length separated with intersections. Two modes of undulator tapering can be implemented: step tapering, and smooth tapering. Procedure of the step tapering applies step change of the undulator gap from module to module, and smooth tapering assumes additional linear change of the gap along each module. In this report we simulate the performance of the both experimental options and compare with theoretical limit. [] E.A. Schneidmiller and M.V. Yurkov, Optimization of a high efficiency free electron laser amplifier, Phys. Rev. ST Accel. Beams 18 (2015) 030705.
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WEPAB032	A Novel Optical Beam Concept for Producing Coherent Synchrotron Radiation with Large Energy Spread Beams	radiation, laser, electron, photon	2646
	R. Rossmanith, A. Bernhard, V. Saile, P. Wesolowski KIT, Karlsruhe, Germany R.W. Aßmann, U. Dorda, B. Marchetti DESY, Hamburg, Germany
	Up to now two FEL concepts are known in conventional accelerators: 1.) In THz lasers an off-crest cavity adds a chirp to the bunch followed by a bunch compressor. Particles with different energies travel on different trajectories to the radiator. 2.) For EUV and X-ray FELs the beam enters an undulator which produces microbunches which then radiate. In this paper it is proposed to copy the THz laser scheme for EUV lasers. The incoming beam is chirped and a dogleg forces afterwards the particles with different energies to move on different parallel trajectories. Considering a detector plane perpendicular to the trajectories the particles with different energies arrive in general at different times. When in this plane for instance a TGU (Transverse Gradient Undulator) is positioned the emitted radiation in the TGU is monochromatic. If in addition chirp and dogleg are selected in such a way that the particles with different energies arrive at the same time at the entrance of the TGU the radiation is monochromatic and coherent similar to the THz laser concept.
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WEPAB035	Elettra Status Present Upgrades and Plans	operation, controls, photon, storage-ring	2657
	E. Karantzoulis, A. Carniel, M. Cautero, B. Diviacco, S. Krecic, R. Visintini Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	The operational status of the Italian 2.4/2.0 GeV third generation light source Elettra is presented together with an account of some present upgrades and plans for the near future.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB035
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WEPAB041	Status Report of Hiroshima Synchrotron Radiation Center Hiroshima University	synchrotron, synchrotron-radiation, radiation, photon	2672
	S. Matsuba, K. Goto, K. Kawase HSRC, Higashi-Hiroshima, Japan
	The Hiroshima Synchrotron Radiation Center (HSRC) at Hiroshima University was established in 1996 for the research of solid state physics. The HSRC equips a 700 MeV electron storage ring nicknamed HiSOR. Recently, we are considering upgrade of the instrumentation beamline for the optical monitoring. In this paper, we report the present status of HSRC.
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WEPAB047	Concept of a New Generation Synchrotron Radiation Facility KEK Light Source	lattice, cavity, emittance, brightness	2687
	T. Honda KEK, Ibaraki, Japan
	KEK has proposed a new SR facility: KEK Light Source (KEK-LS) towards the completion of the first half of the 2020s. The energy and the natural horizontal emittance are 3 GeV and 0.13 nm rad, respectively. To mitigate the intra-beam scattering effect, we are planning to install third harmonic RF cavities. The extremely low emittance ring has been designed based on the Hybrid Multi-Bend Achromatic (HMBA) lattice, which was originally developed at the ESRF upgrade project. We have modified it to insert a short straight section at the center of the unit cell. The number of unit cells is 20, and the circumference is about 570 m. Except for an RF section and an injection section, the ring can accommodate 18 undulators in the long straight sections of 5.6 m, and the additional 20 short straight section of 1.2 m will be used for short-period narrow-gap undulators. If we assume an undulator of the magnetic period 20 mm, total length 5.0 m, and the smallest gap 4 mm, the SR brightness approaches 10²² Photons/mrad²/mm²/s/0.1%B.W. at the X-ray range. It has a high coherent fraction of about 20% at the diffraction limit wavelength 0.32 keV.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB047
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WEPAB058	Commissioning Status of the Dalian Cohernet Light Source	FEL, laser, electron, linac	2709
	G.L. Wang DICP, Dalian, People's Republic of China
	The Dalian Coherent Light Source (DCLS) is a seeded FEL user facility working at 50-150 nm, now under commissioning in Dalian, China. The facility consists of a 300 MeV normal-conducting S-band linear accelerator (LINAC) and two undulator beamlines. The first beam-line (FEL-1) will provide picosecond FEL radiation with the pulse energy up to several hundreds micro-joule, the second beam-line (FEL-2) will be a femtosecond and polarization FEL. The LINAC and FEL-1 beam-line construction was complete by the summer of 2016, the installation of FEL-2 is in preparation. High power RF conditioning of the LINAC started in August 2016 and the beam commissioning initiated 3 months later. This article describes the commissioning status of DCLS, reports on the goals achieved so far.
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WEPAB065	Proposal for the Generation of Terawatt, Attosecond X-Ray Pulses in Free Electron Lasers	radiation, laser, electron, FEL	2723
	Z. Wang, C. Feng, Z.T. Zhao SINAP, Shanghai, People's Republic of China
	A feasible novel method is proposed to generate attosecond terawatt X-ray radiation pulse in free electron lasers, which could find its application on multiple science fields. In our scheme, a chirped laser is employed to generate a chirped periodic current enhancement and a series of spatiotemporal shifters are applied between the undulator sections to generate ultra-short radiation pulse. Three-dimensional start-to-end simulations are carried out and the calculation results show that a 0.15nm X-ray pulse with the peak power of about 1TW and the pulse length of 0.1fs could be achieved in our scheme.
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WEPAB072	Apple II Undulator and Front End Design for the New LOREA Beamline at ALBA	polarization, vacuum, dipole, wiggler	2747
	J. Campmany, L.G.O. Garcia-Orta, J. Marcos, V. Massana ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
	ALBA synchrotron has started the construction of a new beamline LOREA, for Low-Energy Ultra-High-Resolution Angular Photoemission for Complex Materials. It will operate in the range of 10 to 1500 eV and will use polarized light. In order to produce the light to be used in this beamline, several options have been studied, and finally an Apple II design has been chosen. The device can operate as an undulator at low energies and as a wiggler at high energies, reaching a wide energy range. The high demanding characteristics of the beamline in terms of energies lead to a device providing high power and wide beam in some working modes. This situation has been a challenge for the Front End design, especially for the vertically polarized mode, with some changes with respect to standard ALBA front ends. In this paper we present the magnetic design and expected performances of the device, that currently is being built by KYMA, as well as the Front End design, that currently is being built by RMP and TVP.
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WEPAB074	On the Coherence Properties of FEL	FEL, laser, simulation, experiment	2753
	M.A. Pop, F. Curbis, S. Werin MAX IV Laboratory, Lund University, Lund, Sweden
	Free Electron Lasers (FEL) are one of the most brilliant light sources in the world and their unique properties are driving worldwide research in understanding and improving them. Numerous papers have already been published describing the output of the FEL in terms of coherence and bandwidth. In this contribution, however, we focus on how the coherence evolves along the FEL undulator and on what factors influence it the most. Using Genesis⁻¹.3* we have been able to follow and record the light field as it is being produced in the undulator. Our analysis method takes advantage of the extensively studied double pinhole experiment and uses the principles behind it to create a tool for extracting coherence information from the radiation field. We will present the scope, limitations and advantages of these virtual experiments as well as an application on an example FEL, to showcase what kind of information can be extracted using this method. * Numerical simulation code used for particle and field distribution tracking along the undulator developed by Sven Reiche
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WEPAB077	The Soft X-Ray Laser Project at MAX IV	laser, FEL, electron, linac	2760
	S. Werin, J. Andersen, F. Curbis, L. Isaksson, M. Kotur, F. Lindau, E. Mansten, D. Olsson, H. Tarawneh, P.F. Tavares, S. Thorin MAX IV Laboratory, Lund University, Lund, Sweden S. Bonetti, A. Nilsson Stockholm University, Stockholm, Sweden V.A. Goryashko Uppsala University, Uppsala, Sweden P. Johnsson Lund University, Lund, Sweden M. Larsson, P. Salén FYSIKUM, AlbaNova, Stockholm University, Stockholm, Sweden O. Tjernberg KTH Physics, Stockholm, Sweden
	A soft x-ray laser beamline utilising FEL technology is being designed for the Short Pulse Facility (SPF) at the MAX IV Laboratory. A conceptual design study has been started following on the scientific case already prepared in collaboration between several Swedish Universities and driven by a strong (Swedish) user demand []. The baseline goal of the SXL beamline is to generate intense and short pulses in the range 1-5 nm (1-0.2 keV). The system is building on the MAX IV linac system, already today providing 3 GeV and pulses compressed to 100 fs for other applications within the SPF. As a special feature we foresee a variety of pump-probe capabilities. We here describe design issues and solutions for the accelerator and FEL system. http://frielektronlaser.se/onewebmedia/SXL_science_case₁61102.pdf
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WEPAB083	Development of Linac-Based MIR/THz FEL Facility and Photocathode RF-gun in Thailand	electron, FEL, laser, gun	2763
	K. Buakor, N. Chaisueb, K. Damminsek, S. Rimjaem, J. Saisut, C. Thongbai, W. Thongpakdi Chiang Mai University, Chiang Mai, Thailand
	A linac-based MIR/THz free-electron laser facility is under the development at the Plasma and Beam Physics Research Facility, Chiang Mai University. The ultimate goal of the project is to generate the infrared radiation covering the wavelengths from 13 to 125 μm. The main applications of the radiation involved MIR/THz imaging and spectroscopy. The future FEL facility will consists of an injector system, an experimental station for coherent transition radiation, two magnetic bunch compressors and two undulator magnets equipped with optical cavities for MIR and THz beamlines. An expected electron beam energy is between 10 to 20 MeV with an energy spread of about or less than 1 %. Two undulator magnets with maximum undulator parameters of 1 and 0.95 will be used for generation of the THz-FEL and MIR-FEL, respectively. In this paper, we present the status of the design and construction of this future FEL facility.
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WEPAB084	Development of Injector System for MIR/THz Free-Electron Laser Facility in Thailand	electron, gun, simulation, FEL	2767
	W. Thongpakdi, S. Rimjaem Chiang Mai University, Chiang Mai, Thailand
	Development of a linac-based MIR/THz FEL light source is ongoing at the Plasma and Beam Physics Research Facility, Chiang Mai University. The future facility will consist of an S-band thermionic cathode RF electron gun, a pre-magnetic bunch compressor in a form of alpha magnet, an S-band travelling-wave linac structure, a 180-degree achromat system and two undulator magnets equipped with optical cavities. This research focuses on start-to-end beam dynamics simulations of the injector system. The aim of the study is to produce high quality electron beam at the entrance of the THz undulator magnet. The simulation was conducted by using programs PARMELA and ELEGANT. The program PARMELA was utilized to study the electron beam dynamics inside the RF-gun. Then, the program ELEGANT was used to optimize the injector system parameters. Optimization of physical specifications for the achromat system was performed to obtain short electron bunches with small energy spread at the undulator entrance. In this paper, results of beam dynamics simulations with suitable condition for the THz-FEL beamline are presented and discussed.
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WEPAB086	Design and Optimisation of SPS-II Storage Ring	emittance, lattice, dipole, dynamic-aperture	2773
	P. Klysubun, T. Pulampong, P. Sudmuang SLRI, Nakhon Ratchasima, Thailand
	Siam Photon Source (SPS) in Thailand has been operating and providing synchrotron radiation to users for more than a decade, leading to growing user community in South East Asia region. This gives rise to the possibility of constructing a new 3 GeV light source which could provide synchrotron light with higher photon energy and higher brilliance than the existing 1.2 GeV machine. Hybrid multi-bend achromat (HMBA) lattice design providing small natural beam emittance is a promising choice. In this paper, the Double-Triple Bend Achromat (DTBA) design with extra straight section scaled from Diamond Light Source upgrade lattice [ref.] is presented. Lattice optimisation with simplified magnet specifications still allows natural emittance of about 900 pm'rad for a 321.3 m circumference ring with sufficient dynamic aperture.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB086
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WEPAB090	Developments in the CLARA FEL Test Facility Accelerator Design and Simulations	FEL, laser, simulation, optics	2787
	P.H. Williams, D.J. Dunning, N. Thompson STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, 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. The requirement to co-propagate the beam with laser seeds of very different wavelengths has led to a redesign of the section preceding the undulators, with a dogleg being replaced by a chicane. Additional refinements of the facility design include the inter-undulator sections. With this finalised design we show start to FEL simulations for all beam modes envisaged.
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WEPAB097	Modelling Two-Colour FEL with Wide Wavelength Separation and Individual Polarisation Tuning	polarization, FEL, simulation, electron	2808
	D. Bultrini, N. Thompson Cockcroft Institute, Warrington, Cheshire, United Kingdom R.J. Allan The Hartree Centre, Science and Technology Facilities Council (STFC/DL), Warrington, United Kingdom L.T. Campbell, B.W.J. MᶜNeil USTRAT/SUPA, Glasgow, United Kingdom D.J. Dunning, N. Thompson STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom J.D.A. Smith TXUK, Warrington, United Kingdom
	Free electron lasers (FELs) are currently enabling cutting edge research in chemistry, biology and physics. We use simulations to assess a new FEL capability that would add to the impressive repertoire of experiments made possible by the technology: a two-colour independent polarization mode, which allows for light pulses with variable temporal separation, individually tuneable polarisation, and widely separated wavelength. Simulations are carried out using the broad bandwidth FEL code Puffin, the results of which are used to discuss the radiation properties of the output. This scheme is applicable to existing and proposed facilities which feature undulators with variable ellipticity and gap.
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WEPAB098	Dielectrically-Loaded Waveguide as a Microwave Undulator for High Brillance X-Rays at 45 - 90 Kev	brightness, photon, operation, coupling	2812
	R. Kustom, A. Nassiri, G.J. Waldschmidt ANL, Argonne, Illinois, USA
	The HEM12 mode in a cylindrical, dielectrically-loaded waveguide provides E and H fields on the central axis that are significantly higher than the fields on the conducting walls. This structure, operating near the cutoff frequency of the HEM12 mode, spans a frequency range where the wavelength and phase velocity vary significantly. This property can be exploited to generate undulator action with short periods for the generation of high brightness x-rays. The frequency range of interest would be from 18 to 34.5-GHz. The goal would be to generate x-rays on the fundamental mode over a range of 45 to 90-kev. The tunability would be achieved by changing the source frequency while maintaining a constant on-axis equivalent undulator field strength of 0.5-T.
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WEPAB109	Multipole Field Effects in a Transverse Gradient Undulator	multipole, FEL, electron, simulation	2833
	P. Baxevanis, Z. Huang SLAC, Menlo Park, California, USA
	Using a transverse gradient undulator (TGU) is one of the methods proposed in order to enable the utilization of electron beams with large energy spread (such as those from plasma-based accelerators) in a free-electron laser (FEL). Most of the analytical treatments of this scheme assume a linear variation of the undulator field with one of the transverse coordinates. While this assumption leads to a simplified and more tractable model, including higher-order multipoles allows us to offer a more complete and rigorous description of the system. In this paper, we investigate the magnetic field components of a TGU using both theory and simulation and explore the impact of higher-order multipoles on the FEL performance.
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WEPAB118	High Power Sub-Femtosecond X-Ray Pulse Study for the LCLS	electron, simulation, space-charge, photon	2848
	J.P. MacArthur Stanford University, Stanford, California, USA J.P. Duris, Z. Huang, A. Marinelli SLAC, Menlo Park, California, USA
	The desire to resolve sub-femtosecond electron dynamics has pushed FEL facilities to shorter pulse lengths. However, current short-pulse schemes provide low pulse energy and a gain-length limited lower bound on the pulse duration. The X-ray Laser-Enhanced Attosecond Pulses (XLEAP) project at SLAC is designed implement an Enhanced Self Amplified Spontaneous Emission (ESASE) scheme, which produces sub-fs current spikes by modulating and compressing the electron beam. We show through a series of Genesis simulations that the current spike is capable of producing sub-fs pulses with a peak power well above 100 GW. Space-charge induced beam chirp can decrease pulse lengths below 400 as, and multi-stage schemes can increase peak x-ray powers to around 1 TW.
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WEPIK053	Studies of Delta-Type Undulators for Sirius	polarization, storage-ring, lattice, dynamic-aperture	3045
	L.N.P. Vilela, L. Liu, X.R. Resende, F.H. de Sá LNLS, Campinas, Brazil
	In this work we present the studies of the effects of Delta-type undulators in the storage ring beam dynamics of Sirius. The undulators were included in the ring model as kick maps and their effects on tune shift, dynamic aperture and beam lifetime were evaluated.
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WEPIK058	Preliminary Longitudinal Impedance Model for the ESRF-EBS	impedance, vacuum, simulation, storage-ring	3063
	S.M. White ESRF, Grenoble, France
	In light sources, longitudinal beam coupling impedance can deteriorate performance through bunch lengthening or increased longitudinal emittance due to the microwave instability. Simulation estimates are therefore required to devise the appropriate counter-measures if necessary. The main contributors to the longitudinal impedance model of the new ESRF-EBS storage ring were simulated. A preliminary longitudinal impedance model is presented and preliminary tracking simulations are shown.
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WEPIK062	UNDUMAG - A New Computer Code to Calculate the Magnetic Properties of Undulators	synchrotron, damping, synchrotron-radiation, radiation	3071
	M. Scheer HZB, Berlin, Germany
	A new code for the magnetic design of undulators is under development at the Helmholtz-Zentrum Berlin (BESSY). The program reads in the geometry and material properties of the undulator magnets and iron poles. Magnetic fields, forces and torques, as well as trajectories and synchrotron radiation can be calculated. The code is a stand-alone FORTRAN program, thus, only a FORTRAN compiler is needed to install it. Build-in graphic routines allows to write postscript files to visualize the geometry and the fields. Other results like 3D field maps, field integrals etc. are written to ASCII files for later use. The code will be published under the GNU general public license. First results and comparison to other codes are presented.
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WEPIK073	Three Dimensional Wake Field for an Electron Moving in Undulator	electron, radiation, electromagnetic-fields, wakefield	3098
	K. Ohmi KEK, Ibaraki, Japan
	Electro-magnetic field for given trajectory of an electron is calculated by Lienard-Wiechert potential. The field near the electron moving in an undulator is presented. The field is regarded as a wake field in the undulator. Motion of a bunch is studied in the wake field.
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WEPIK080	Preliminary Study of Beam Dynamics Compensation for the Elliptically Polarized Undulator at the HLS-II	electron, simulation, software, dynamic-aperture	3114
	Z.H. Yang, Z.H. Bai, W. Li, L. Wang USTC/NSRL, Hefei, Anhui, People's Republic of China
	An elliptically polarized undulator (EPU) was installed at the upgraded Hefei Light Source, HLS-II, for special users. Due to that the area of good field of the EPU is not large enough, the resulting beam dynamics is serious. At present, the lattice is changed to lower beta functions at the EPU to solve this problem. However, the compensation for the EPU is necessary for better operation of the machine in the future. In this paper, we used the surface fitting method to extract the Hamiltonian of the EPU from the real surface magnetic field data. Thus, we can obtain the effective Hamiltonian of the ring, which can be analyzed using normal form or other techniques. Then the beam dynamics effects resulting from the EPU can be compensated by optimizing the nonlinear quantities with striplines.
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WEPIK100	The Applicability of NEG Coated Undulator Vessels for the CLARA FEL Test Facility	vacuum, FEL, wakefield, impedance	3181
	O.B. Malyshev, K.B. Marinov, K.J. Middleman, N. Thompson, R. Valizadeh, P.H. Williams STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom O.B. Malyshev, K.J. Middleman, N. Thompson, R. Valizadeh, P.H. Williams Cockcroft Institute, Warrington, Cheshire, United Kingdom
	CLARA is a FEL test facility at Daresbury Laboratory (DL), UK. The undulator vacuum chamber is 20 m long with inner diameter 6 mm and its vacuum performance can benefit from a NEG coating. The thickness of the coating layer must be carefully optimised. A layer ~ 1 um would help the vacuum but a thinner layer would be partially transparent for the EM field reducing the resistive wall wakefields due to the NEG. A very thin layer, however, may not yield the necessary vacuum performance. Two types of NEG coatings produced at DL - dense and columnar - were considered. Their bulk conductivities were measured in a separate study. The resistive wall wakefield impedance was calculated following the standard approach for multilayer vessels. A 250 fs rms electron bunch was generated in ASTRA and its wakefield was obtained from the vessel impedance. The FEL performance was then studied through GENESIS simulations and the result compared to the case with no wakefields. It was found that NEG layers thicker than 100 nm give an unacceptable reduction of the FEL power and the vacuum performance of such thin coatings is unknown. Possible solutions to this problem are discussed.

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MOXAA1

Commissioning of the European XFEL Accelerator

linac, operation, electron, emittance

1

W. Decking, H. Weise
DESY, Hamburg, Germany

The European XFEL uses the world's largest superconducting RF installation to drive three independent SASE FELs. After eight years of construction the facility is now brought into operation. First experience with the superconducting accelerator as well as beam commissioning results will be presented. The path to the first user experiments will be laid down.

Slides MOXAA1 [22.967 MB]

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MOPAB050

Reconstruction of Sub-Femtosecond Longitudinal Bunch Profile Measurement Data

laser, electron, diagnostics, cavity

207

M.K. Weikum, R.W. Aßmann, U. Dorda
DESY, Hamburg, Germany
G. Andonian
RadiaBeam, Santa Monica, California, USA
G. Andonian
UCLA, Los Angeles, California, USA
Z.M. Sheng, M.K. Weikum
USTRAT/SUPA, Glasgow, United Kingdom
Z.M. Sheng
Shanghai Jiao Tong University, Shanghai, People's Republic of China

With a current trend towards shorter electron beams with lengths on the order of few femtoseconds (fs) to sub-femtoseconds both in conventional and novel accelerator communities, the need for diagnostics with equivalent attosecond resolution is increasing. The proposed design for a sub-femtosecond diagnostic by Andonian et al.* is one such example that combines a laser deflector with an RF deflecting cavity to streak the electron beam in the horizontal and vertical direction. In this paper, we present a tool for the reconstruction of the longitudinal beam profile from this diagnostic data, which can be used both for the analysis of planned experiments and testing of different beam scenarios with respect to their specific setup requirements. Applying this method, the usefulness of the device for measurements in a number of example scenarios, including plasma-accelerated and ultrashort RF-accelerated electron beams, is discussed.
*G. Andonian, E. Hemsing, D. Xiang, P. Mumuseci, A. Murokh, S. Tochitsky, et al, Phys. Rev. Spec. Top-Ac. 14, 072802 (2011).

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MOPAB051

Progress in FLASH Optics Consolidation

optics, emittance, gun, laser

211

J. Zemella, M. Vogt
DESY, Hamburg, Germany

FLASH is the superconducting soft X-ray Free Electron Laser in Hamburg at DESY, Germany. A precise knowledge of the beam optics is a key aspect of the operation of a SASE FEL. A campaign of optics consolidation has started in 2013 when the second beam line FLASH2 was installed downstream of the FLASH linac. We give an update on progress of this effort and on recent results.

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MOPAB075

Measurement of Electron Bunch Length via a Tunable-Gap Undulator

radiation, electron, laser, acceleration

295

X.L. Su, Y.-C. Du, W.-H. Huang, L. Niu, C.-X. Tang, Q.L. Tian, D. Wang, L.X. Yan
TUB, Beijing, People's Republic of China
Y.F. Liang
Tsinghua University, Beijing, People's Republic of China

A THz undulator with widely tunable gap is constructed and installed at Tsinghua University beamline, which is applied for narrow-band THz radiation and measurements of electron bunch longitudinal structure. This is a planar electromagnetic device with 8 regular periods, each 10 cm long. The field range B=0.15- 0.99 T peak field on axis while changing the gap from 75mm to 23mm. In the experiments, we scanned the undulator gap to measure the radiation intensity at different resonant frequency, thus we can get the bunch length even form factor of the bunch. The demonstrated experimental results show that the bunch of 220pC compressed by chicane in Tsinghua beamline is about 120fs (rms), which agree well with the simulations. The resolution of bunch length measurement with this method can be attoseconds by optimized undulator. Furthermore, the form factor of electron bunch train can also be measured.

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MOPAB149

Design of LCLS-II ATCA BPM System

linac, network, FEL, controls

477

A. Young, R. Claus, J.M. D'Ewart, J.C. Frisch, G. Haller, R.T. Herbst, S. L. Hoobler, U. Legat, J.J. Olsen, R. Ruckman, L. Sapozhnikov, S.R. Smith, T. Straumann, J.A. Vásquez, M. Weaver, E. Williams, C. Xu
SLAC, Menlo Park, California, USA

Funding: Work supported by U.S. Department of Energy under Contract Numbers DE-AC02-06CH11357
SLAC's LCLS-II is a next generation X-ray FEL that will use a CW 4 GeV superconducting linac with nominal bunch spacing of 1us will deliver both soft and hard x-ray FEL to users. In order to achieve the required performance, the SLAC Technical Innovation Directorate has developed a common hardware and firmware platform for beam instrumentation based on the ATCA crate format. We have designed a stripline and cavity BPM system based on this platform that is capable of measuring the beam position at full beam rate. The system will have a dynamic range between 1 pC to 300 pC. This paper will discuss the design of the BPM electronics, overall architecture and performance on LCLS-I.

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MOPIK069

Approximate Matrices for Modeling the Focusing of the Undulator Periods and Undulator End Fields

focusing, betatron, dipole, laser

686

V. Balandin, N. Golubeva
DESY, Hamburg, Germany

We describe procedure for constructing approximate matrices for modeling the focusing of the undulator periods and undulator end fields and discuss applicability of these matrices to the European XFEL undulators.

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MOPIK078

Narrow-Band, Wide-Range Tuneable THz Source Based on the Slotted-Foil Technique

electron, radiation, simulation, FEL

712

J. Pfingstner, E. Adli, H. Holmestad
University of Oslo, Oslo, Norway
S. Bettoni, S. Reiche
PSI, Villigen PSI, Switzerland

The FEL user community has expressed a strong interest in a THz source for the excitation of their samples in pump probe experiments. The demanded THz properties are challenging to achieve, as they include a narrow bandwidth of <5-10%, the possibility of frequency tuning between 1 and 20 THz, a THz pulse energy of about 100 uJ, and a fixed phase relation from shot-to-shot. To fulfil these specifications, an accelerator-based source is proposed in this paper. It utilises the slotted-foil technique to create a pre-bunched electron beam that is injected into a helical undulator. Detailed simulation studies presented in this paper show that the corresponding undulator radiation has the demanded properties.

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MOPVA002

Initial Stage of Self Amplified Radiation Emission From Electron Bunches in Crystal: Linear Response Theory

radiation, electron, brightness, polarization

848

A.I. Benediktovitch, I. Lobach
BSU, Minsk, Belarus, Belarus

Self amplified spontaneous emission (SASE) is a key process in X-ray free electron lasers' operation. In this case the spontaneous emission is undulator radiation emission, the radiation in X-ray range being possible from electrons in GeV energy range. In the case of interaction of electrons with properly aligned crystal the channeling radiation results in X-rays from electrons with energies in tens MeV energy range. In this situation for high current densities the SASE process may take place that potentially could lead to construction of a compact bright X-ray source. In present contribution the first principle theoretical description is outlined and first order perturbation theory is used to model the initial stage of SASE. The transition from spontaneous to SASE regime is described, the requirements for bunch current and emittance are determined. By means of dispersion equation analysis and boundary condition application the intensity radiated from crystal slab is calculated and it is shown that Bragg diffraction could enhance self amplification. A numerical example for Si (001) illustrates the model.

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MOPVA004

Operating Simultaneously Two In-Vacuum Canted Undulators in Synchrotron SOLEIL

photon, vacuum, radiation, electron

851

L.S. Nadolski, Y.-M. Abiven, P. Brunelle, N. Béchu, M.-E. Couprie, F.J. Cullinan, X. Delétoille, M. El Ajjouri, C. Herbeaux, N. Hubert, N. Jobert, M. Labat, J.-F. Lamarre, A. Lestrade, A. Loulergue, O. Marcouillé, P. Monteiro, A. Nadji, R. Nagaoka, D. Pédeau, P. Rommeluère, K.T. Tavakoli, M. Valléau, J. Vétéran
SOLEIL, Gif-sur-Yvette, France
C. Benabderrahmane
ESRF, Grenoble, France

Each long SOLEIL beamline, ANATOMIX and Nanoscopium, takes a photon beam from an in-vacuum undulator with a minimum gap of 5.5 mm. The canted radiation sources are installed in a long straight section of the storage ring. The first closure of both undulators led to the severe damage of the downstream undulator in 2011. The reason for this incident has been investigated and clearly identified. A long-term project has enabled us to find a technical solution for a simultaneous operation of both undulators. A special angle fast interlock was designed and a dedicated photon absorber has been introduced at the entrance of the second undulator while keeping the impact on the beam performance as low as possible. The main technical steps will be reported with an interim solution put in place in spring 2015 and a final solution deployed and validated in May 2016.

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MOPVA026

Effects of Insertion Devices on Stored Electron Beam of High Energy Photon Source

photon, emittance, insertion, brilliance

911

X.Y. Li, Z. Duan, D. Ji, Y. Jiao, Y.F. Yang
IHEP, Beijing, People's Republic of China

The High Energy Photon Source (HEPS) is a 4th generation, 6-Gev, ultralow-emittance, photon source project in China. High brightness hard X-ray beams at the energy particularly above 10kev are provided by insertion devices installed in straight sections of the storage ring. Brightness tuning curves of 14 ID beamlines planned in HEPS first stage are obtained after designing their parameters. However the presence of these insertion devices produce several effects on the beam performances including betatron tunes, betatron amplitude functions, closed orbit, emittance and dynamic aperture etc. It is found that the vertical octupole effect due to the fourteen IDs under the present schemes produce the most significant effect on the vertical dynamic aperture reduction. The ID field error effects on close orbit can be completely compensated by two correctors adjacent the ID at the both side. The horizontal emittance reduces to 36pm.rad due to the damping wiggler effect of IDs with field error after the orbit correction is also obtained.

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MOPVA033

A Compact Thermionic RF Injector with RF Bunch Compression fed by a Quadrupole-Free Mode Launcher

gun, cathode, electron, linac

924

F. Toufexis, V.A. Dolgashev, C. Limborg-Deprey, S.G. Tantawi
SLAC, Menlo Park, California, USA

Funding: This project was funded by U.S. Department of Energy under Contract No. DE-AC02-76SF00515, and the National Science Foundation under Contract No. PHY-1415437.
We present a design for a compact X-Band RF thermionic injector consisting of two iris-loaded accelerator structures. Both structures are fed by a single quadrupole-free TM01 mode launcher. In the first structure the electron bunches are extracted from a thermionic cathode. The second structure creates an energy chirp in the bunch for its further ballistic compression. This injector can produce short electron bunches without the need for a magnetic bunch compressor. We are developing this injector as part of a linac-based 91.392 GHz RF power source, which further comprises a booster linac and a mm-wave decelerator structure that extracts 91.392 GHz RF power from the electron beam. This source will be used to power a short-period RF undulator with 1.75 mm period*.
* F. Toufexis and S.G. Tantawi, A 1.75 mm Period RF-Driven Undulator, these proceedings.

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MOPVA034

A Compact EUV Light Source Using a mm-Wave Undulator

electron, gun, impedance, quadrupole

928

F. Toufexis, V.A. Dolgashev, C. Limborg-Deprey, S.G. Tantawi
SLAC, Menlo Park, California, USA

Funding: This project was funded by U.S. Department of Energy under Contract No. DE-AC02-76SF00515, and the National Science Foundation under Contract No. PHY-1415437.
We are building an Extreme Ultra Violet (EUV) light source based on a 1.75 mm period RF undulator*. We will use a thermionic X-Band injector which utilizes RF bunch compression. The beam is accelerated using an X-Band traveling wave accelerating structure followed by a high shunt impedance standing wave accelerating structure up to 129 MeV. The beam then goes through a 91.392 GHz RF undulator with a period of 1.75 mm, producing EUV radiation around 13.5 nm. The RF undulator is powered by a 91.392 GHz decelerating structure, which extracts the RF power from the spent electron beam. The length of the entire beam line from the cathode to the beam dump is approximately 6 m. We describe the design and projected operating parameters for this EUV light source.
* F. Toufexis and S.G. Tantawi, A 1.75 mm Period RF-Driven Undulator, these proceedings.

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TUXA1

Towards Diffraction Limited Storage Ring Based Light Sources

emittance, storage-ring, lattice, electron

1203

L. Liu, H. Westfahl Jr.
LNLS, Campinas, Brazil

Experimental x-ray techniques that benefit from the great increase in brightness and coherent flux provided by the fourth generation of synchrotron light sources, based on recent advances in accelerator design and technology, are widely expanding nowadays. The basic ingredient to higher brightness is a further reduction of the electron beam emittance in storage rings dedicated to light sources. However, to fully explore the potential of these new sources, it is necessary to optimize other variables as well, such as the proper matching of electrons and photons phase-space and the possibility of using new kinds of insertion devices. Equally important is to try new ways to improve the integration between the light source capabilities and the experiment needs. In this work, recent progress of low emittance rings will be reviewed and the efforts to improve transverse coherent flux and source-to-beamline integration at the Brazilian Sirius project will be described.

Slides TUXA1 [11.984 MB]

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TUOAA2

A Soft X-Ray Free-Electron Laser Beamline of SACLA

FEL, electron, photon, laser

1209

K. Togawa, T. Asaka, N. Azumi, T. Hara, T. Hasegawa, N. Hosoda, T. Inagaki, T. Ishikawa, R. Kinjo, C. Kondo, H. Maesaka, S. Matsui, T. Ohshima, Y. Otake, S. Owada, H. Tanaka, T. Tanaka, M. Yabashi
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
T. Bizen, H. Kimura, S. Matsubara, K. Nakajima, T. Sakurai, T. Togashi, K. Tono
JASRI/SPring-8, Hyogo, Japan
T. Fukui
RIKEN SPring-8 Center, Innovative Light Sources Division, Hyogo, Japan

At the Japanese x-ray free-electron laser (FEL) facility, SACLA, the beamline-1 has been upgraded from a spontaneous radiation to a soft x-ray FEL beamline, which generates FEL lights over a wide wavelength range from the extreme-ultraviolet to the soft x-ray regions. We started operation for users in July 2016. A dedicated accelerator, which is a refinement of the SCSS test accelerator operated in 2005-2013, was installed beside the XFEL beamlines in the SACLA undulator hall. The SCSS concept to make an FEL facility compact was continuously adopted. In the 2016 summer shutdown period, the beam energy was upgraded from 500 MeV to 800 MeV by adding two C-band rf units. The maximum K-value of the undulator magnet is 2.1. The available wavelengths of the FEL lights were extended to the range from 8 to 50 nm with pulse energies between a few to few tensμJ at an operational repetition rate of 60 Hz. In this conference, we will report an overview of the upgraded SACLA-beamline-1 and characteristics of the FEL light pulse.

Slides TUOAA2 [15.457 MB]

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TUOAA3

Progress of Pr2Fe14B Based Hybrid Cryogenic Undulators at SOLEIL

cryogenics, radiation, electron, photon

1213

A.M. Ghaith, P. Berteaud, F. Blache, F. Briquez, N. Béchu, M.-E. Couprie, J. Da Silva Castro, J.M. Dubuisson, C. Herbeaux, C.A. Kitegi, A. Lestrade, O. Marcouillé, F. Marteau, M. Sebdaoui, G. Sharma, A. Somogyi, K.T. Tavakoli, M. Tilmont, M. Valléau
SOLEIL, Gif-sur-Yvette, France
C. Benabderrahmane
ESRF, Grenoble, France

Cryogenic Permanent Magnet Undulators (CPMUs) take advantage of the enhanced field performance of permanent magnets when cooled down to low temperature, enabling shorter period with sufficient magnetic field to achieve high brightness radiation in the X-ray domain. Several CPMUs have been manufactured at SOLEIL. The first CPMU of period 18 mm (U18), optimized with a phase error of 3.2° at temperature of 77 K, has been installed and operated for the past 5 years at SOLEIL for the NANOSCOPIUM beamline. We report on photon beam based alignment enabling for a better adjustment of the vertical position offset of the undulator with a precision of 50 μm, and on the correction of the taper with a precision of 5 μrad to enhance the radiation flux. A second U18 cryo-ready undulator, with a new mechanical and magnetic sorting of module shimming, has attained a phase error of 2.3° at CT without any further adjustments after the assembly. Currently, two more CPMUs are being built; a 2 m long U18 for the SOLEIL ANATOMIX beamline, and a 3 m long U15 undulator reaching a magnetic gap of 3 mm. The new challenges encountered with magnetic measurements and mechanical designs for U15 are presented.

Slides TUOAA3 [3.491 MB]

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TUPAB026

Status of the Cryogenic Undulator CPMU-17 for EMIL at BESSY II / HZB

vacuum, Windows, permanent-magnet, feedback

1372

J. Bahrdt, J. Bakos, W. Frentrup, S. Gottschlich, C. Kuhn, G. Pfeiffer, C. Rethfeldt, A. Rogosch-Opolka, M. Scheer, B. Schulz, L. Ziemann
HZB, Berlin, Germany

The CPMU-17 is the hard X-ray radiation source of a canted double undulator system for the Energy Materials In-situ Laboratory EMIL at BESSY II [1]. Various ambitious concepts are realized in this undulator such as Dy-hardened PrFeB-magnets, direct liquid Nitrogen cooling, dual loop feedback gap drive based on an optical micrometer and a low permeability stainless steel In-Vacuum(IV)-girder without keepers. The magnets are sorted according to Helmholtz coil and stretched wire data. Reproducibility and accuracy measurements of two IV-measurement tools needed for the CPMU-17 are presented: an IV-Hall probe bench and an IV-Moving Wire.

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TUPAB035

Field Quality of 1.5 m Long Conduction Cooled Superconducting Undulator Coils with 20 mm Period Length

multipole, photon, synchrotron, emittance

1395

S. Casalbuoni, N. Glamann, A.W. Grau, T. Holubek, D. Saez de Jauregui
KIT, Eggenstein-Leopoldshafen, Germany
C. Boffo, T.A. Gerhard, M. Turenne, W. Walter
Babcock Noell GmbH, Wuerzburg, Germany

The Institute for Beam Physics and Technology (IBPT) at the Karlsruhe Institute of Technology (KIT) and the industrial partner Babcock Noell GmbH (BNG) are col-laborating since 2007 on the development of superconducting undulators both for ANKA and low emittance light sources. The first full length device with 15 mm period length has been successfully tested in the ANKA storage ring for one year*. The next superconducting undulator has 20 mm period length (SCU20) and is also planned to be installed in the accelerator test facility and synchrotron light source ANKA. The SCU20 1.5 m long coils have been characterized in a conduction cooled horizontal test facility developed at KIT IBPT. Here we present the local magnetic field and field integral measurements, as well as their analysis including the expected photon spectrum.
*S. Casalbuoni et al., Characterization and long term operation of a novel superconducting undulator with 15 mm period length in a synchrotron light source, Phys. Rev. ST Accel. Beams, vol. 19, p.110702, Nov. 2016.

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TUPAB036

Training and Characterization of 1.5m Long Conduction Cooled Superconducting Undulator Coils with 20 mm Period Length

synchrotron, radiation, vacuum, storage-ring

1399

A.W. Grau, S. Casalbuoni, N. Glamann, T. Holubek, D. Saez de Jauregui
KIT, Eggenstein-Leopoldshafen, Germany
C. Boffo, T.A. Gerhard, M. Turenne, W. Walter
Babcock Noell GmbH, Wuerzburg, Germany

The Institute for Beam Physics and Technology (IBPT) of the Karlsruhe Institute of Technology (KIT), and the company Babcock Noell GmbH (BNG) are running an R&D program on superconducting undulators (SCUs). The collaboration is working on a SCU with 20 mm period length (SCU20) for ANKA, the test facility and synchrotron radiation source, run by the IBPT. The 1.5 m long undulator coils have been tested in a conduction-cooled environment. This contribution describes the training, the stability and the thermal behavior of the coils.

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TUPAB041

Improvements in Production of Magnets and Pole Pieces for Undulators

induction, dipole, permanent-magnet, target

1415

F.-J. Börgermann
Vacuumschmelze GmbH & Co. KG, Hanau, Germany

Permanent magnets and highly saturable pole pieces are widely used in the setup of undulators as well as dipoles, quadrupoles and sextupoles. We will present actual improvements of precision, homogeneity and basic material properties in the range of NdFeB-based permanent magnets and CoFe-based soft magnetic alloys.

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TUPAB053

Proof-of-Principle Experiment of Phase-Combined Undulator

permanent-magnet, experiment, gun, electron

1446

R. Kinjo, T. Tanaka
RIKEN SPring-8 Center, Hyogo, Japan
A. Kagamihata
JASRI/SPring-8, Hyogo, Japan

A huge attractive force is the largest concern in designing a mechanical structure of undulators, in which an accurate control and high uniformity of the gap between the upper and lower magnetic girders are required. This problem is especially serious for in-vacuum undulators, in which the girders are located inside the vacuum chamber. We have proposed a new concept called a phase-combined undulator, which has intrinsically no magnetic force*. In this undulator, the magnetic forces acting on the girders locally head to the longitudinal axis instead of the attractive direction, and are actually canceled out in total. Numerical calculations have shown that the attractive force will be reduced down to a negligible level. Recently, we performed a proof-of-principle experiment to examine the feasibility of this undulator concept in terms of the force between the girders and magnetic field distribution, which will be reported in the conference.
* R. Kinjo and T. Tanaka, Phys. Rev. ST Accel. Beams 17, 122401

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TUPAB055

Development of compact magnetic field measurement system available for in-vacuum undulators

brightness, vacuum, emittance, photon

1449

M. Adachi, R. Kato, T. Shioya, K. Tsuchiya
KEK, Ibaraki, Japan

A low-emittance 3-GeV KEK-LS* ring has been designed at KEK. KEK-LS's undulators can produce extremely high brightness light ranging from VUV to X-ray. Brightness of undulator light strongly depends on the phase error of its periodic magnetic field. Then a precise magnetic field adjustment is required in order to prevent the reduction of the brightness performance. Generally, the adjustment is performed by the conventional field measurement system equipped with hole-probes on a huge stone table. But, for the in-vacuum undulator, the measurement must be performed without the vacuum chamber. The additional phase error caused by reattaching the chamber is not negligible for the low emittance rings. Therefore, some groups have developed measurement systems available for the direct field measurement inside the chamber**,***. We have started to develop a compact measurement system. Our system is compacted and stabilized by utilizing the rigid metal beam of the undulator frame instead of the stone table. In the conference, we will report the detail of the system and the present status of the development.
* KEK-LS HP, http://kekls.kek.jp/
** T. Tanaka, et al., Physical Review ST-AB, vol.12, p.120702 (2009).
*** M. Musardo, et al., Proceedings of IPAC2015, Richmond, VA, USA, p.1693 (2015).

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TUPAB064

Development of a PrFeB Cryogenic Permanent Magnet Undulator (CPMU) Prototype at IHEP

vacuum, cryogenics, permanent-magnet, photon

1469

H.H. Lu, W. Chen, L. Gong, X.Y. Li, L.Z. Li, S.C. Sun, Y.J. Sun, Y.F. Yang, L. Zhang, X.Z. Zhang, S.T. Zhao
IHEP, Beijing, People's Republic of China

A PrFeB cryogenic permanent magnet undulator (CPMU) prototype is under construction for High Energy Photon Source Test Facility (HEPS-TF) at IHEP. The device is a full scale in-vacuum undulator with a magnetic length of 2 meters and a period of 13.5 mm, and it will work at less than 85K. The whole design scheme of prototype is presented and the specifications are given, where the consideration of in-vacuum magnetic measurement bench is also included. The development progress is introduced.

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TUPAB066

Mechanical Design of a Cryogenic Permanent Magnet Undulator at IHEP

vacuum, cryogenics, permanent-magnet, photon

1475

S.C. Sun, W. Chen, L. Gong, X.Y. Li, L.Z. Li, H.H. Lu, Y.J. Sun, Y.F. Yang, L. Zhang, X.Z. Zhang, S.T. Zhao
IHEP, Beijing, People's Republic of China

High Energy Photon Source (HEPS) at Institute of High energy Physics (IHEP) is a new 6 GeV third generation electron storage ring. Insertion devices play a significant role in achieving the high performance of the photon source. A 13.5mm period-length Cryogenic Permanent Magnet Undulator (CPMU) prototype is designed and under construction. The mechanical structure designed based on physical requirements will be presented.
Work supported by Project of High Energy Photon Source Test Facility,
email address: sunsc@ihep.ac.cn

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TUPAB068

Design of the CPMU Vacuum System at the HEPS

vacuum, cryogenics, radiation, photon

1482

L. Zhang, H.H. Lu, S.C. Sun
IHEP, Beijing, People's Republic of China

The High Energy Photon Source (HEPS) is a 3rd generation synchrotron radiation light source. Its beam energy is 6 GeV and its emittance is less than 60 pm'rad, which can provide high brilliance hard X-rays to several tens of experimental stations. The Cryogenic Permanent Magnet Undulator (CPMU) is one of the key components to achieve the high brilliance. And its vacuum system is necessary to provide an ultra-high vacuum environment for CPMU operation. To design the CPMU vacuum system, we do experiments to test the outgassing rate, estimate the total gas load, calculate the effective pumping speed, design the baking program and select all pumps and other vacuum equipments. This paper presents the design specifications and the assemblage status of the CPMU vacuum system.

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TUPAB071

Experimental Results on THz Superradiation From the Undulator in Tsinghua University Beamline

radiation, electron, detector, experiment

1488

X.L. Su, Y.-C. Du, W.-H. Huang, L. Niu, C.-X. Tang, Q.L. Tian, D. Wang, L.X. Yan
TUB, Beijing, People's Republic of China
Y.F. Liang
Tsinghua University, Beijing, People's Republic of China

In this paper, the first operation of a widely tunable 8-period undulator at terahertz (THz) frequency in Tsinghua University beamline was reported. Superradiate undulator radiation from sub-picosecond electron bunches compressed by chicane was observed. The measured radiation curve shows clearly that the radiation energy is proportional to the charge square, and the THz frequency can be changed from 0.4 THz to 10 THz with narrow-band spectrums. Our results demonstrate a high power and tunable coherent THz source, which could be useful for many applications in the future.

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TUPAB087

Undulator Commissioning Experience at PAL-XFEL

electron, background, radiation, site

1520

D.E. Kim, Y.G. Jung, H.-S. Kang, I.S. Ko, H.-G. Lee, S.B. Lee, W.W. Lee, K.-H. Park, H.S. Suh
PAL, Pohang, Kyungbuk, Republic of Korea
I.S. Ko
POSTECH, Pohang, Kyungbuk, Republic of Korea
J. Pflüger
XFEL. EU, Hamburg, Germany

Pohang Accelerator Laboratory (PAL) is developing a 0.1 nm SASE based FEL based on 10 GeV S-band linear accelerator named PAL-XFEL. The hard X-ray undulator line requires 20 units of 5 m long hybrid-type conventional planar undulator while soft X-ray line requires 7 units of 5 m long hybrid type planar undulators. In this report, the final measurement results of all the undulators, phase matching scheme, and the commissioning experiences will be summarized.

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TUPAB088

Wire Position System to Consistently Measure and Record the Location Change of Girders Following Ground Changes

alignment, electron, power-supply, electronics

1523

H. J. Choi, S.Y. Baek, H.-S. Kang, S.H. Kim, H.-G. Lee, S.B. Lee
PAL, Pohang, Kyungbuk, Republic of Korea

Several parts that comprise the large scientific device should be installed and operated at the accurate three-dimensional location coordinates where they should be subjected to survey and alignment. The location of the aligned parts should not be changed in order to ensure that the electron beam parameters of PAL-XFEL remain stable and can be operated without any problems. As time goes by, however, the ground goes through uplift and subsidence, which consequently deforms building floors. The deformation of the ground and buildings changes the location of several devices including magnets and RF accelerator tubes, which eventually leads to the alignment errors. Once alignment errors occur with regard to these parts, the electron beam deviates from its course and beam parameters change accordingly. PAL-XFEL has installed the Hydrostatic Leveling System to measure and record the vertical change of buildings and ground consistently and systematically and the Wire Position System to measure the two dimensional changes of girders. This paper is designed to introduce the operating principle and design concept of WPS and discuss the current situation regarding installation and operation.

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TUPAB104

Optimized Undulator to Generate Low Energy Photons From Medium to High Energy Accelerators

polarization, photon, optics, radiation

1556

T.Y. Chung, M.-S. Chiu, J.C. Huang, C.-S. Hwang, J.C. Jan, C.K. Yang
NSRRC, Hsinchu, Taiwan
H.W. Luo
NTHU, Hsinchu, Taiwan

While emitting low energy photons from a medium or high energy storage ring, the on-axis heat load on the beam line optics can become a critical issue. In addition, the heat load in the bending magnet chamber, especially in the vertical and circular polarization mode of operation may cause some concern. In this work, we compare the heat loads for the APPLE-II and the Knot-APPLE, both optimized to emit 10 eV photons from the 3 GeV TPS. Under this constraint the heat load analysis, synchrotron radiation performance and features in various polarization modes are presented. Additional consideration is given to beam dynamics effect.

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TUPAB105

Field Measurement System for a Cryogenic Permanent Magnet Undulator in TPS

cryogenics, vacuum, permanent-magnet, multipole

1559

C.K. Yang, C.H. Chang, T.Y. Chung, W.H. Hsieh, J.C. Huang, C.-S. Hwang
NSRRC, Hsinchu, Taiwan

Short period in-vacuum, permanent magnet undulators operating at cryogenic temperatures are being developed worldwide to serve as brilliant and coherent light sources for medium energy storage rings. A hybrid cryogenic permanent magnet undulator (CU) with PrFeB magnets has now been designed and constructed at NSRRC [1]. To characterize the performance and to determine magnetic field errors after cool down poses some technical chal-lenges compared to room temperature undulators. A new system combining a Hall probe and a stretched wire has been designed to measure the field integrals, trajectory, phase errors, and K value under low temperature and vacuum conditions. Field measurements in this cryogenic undulator will be performed around 77 K as well as at room temperature, making temperature dependent calibra-tion of the Hall probes necessary. The main features and improvement of the measurement and calibration system are presented.

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TUPAB106

Development of a Cryogenic Permanent Magnet Undulator for the TPS

vacuum, permanent-magnet, cryogenics, radiation

1562

J.C. Huang, C.H. Chang, T.Y. Chung, C.-S. Hwang, J.C. Jan, C.S. Yang, C.K. Yang
NSRRC, Hsinchu, Taiwan
H. Kitamura
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan

Development of a cryogenic permanent magnet undu-lator (CPMU) at the Taiwan Photon Source (TPS) is the most recent activity toward a new light source for the Phase-II beamlines. A hybrid-type CPMU with a period length of 15 mm is under construction with PrFeB permanent-magnet materials. A maximum effective magnetic field of 1.77 T at a gap of 3 mm is expected when the magnets (PMs) are cooled down around 77 K. The features desired for the TPS CPMU are low-intrinsic-phase-error characteristics and high thermal budget for various kinds of heat loads. The design of the TPS CPMU is discussed in this paper.

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TUPAB114

Design Study for a Plasma Undulator Experiment Using Capillary Based Discharge Plasma Source

laser, plasma, electron, experiment

1584

O. Mete Apsimon, R. Apsimon, Y. Ma, D. Seipt, M.J.V. Streeter, A.G.R. Thomas
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
T.H. Pacey, G.X. Xia
UMAN, Manchester, United Kingdom

A plasma undulator is formed when a short laser pulse is injected into plasma off-axis or at an angle that causes the centroid of this laser pulse to oscillate. Ponderomotively driven plasma wake will follow this centroid given that the product of the plasma wave number and the characteristic Rayleigh length of the laser is much larger than one. This oscillating transverse wakefield may work as an undulator forcing particles to follow sinusoidal trajectories and emit synchrotron radiation. In this paper, plans for an experiment are introduced and resulting radiation and injected beam characteristics are discussed. The aforementioned laser centroid oscillations are demonstrated using, EPOCH, a PIC code for laser-plasma interactions.

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TUPAB116

Insertion Devices at Diamond Light Source: A Retrospective Plus Future Developments

wiggler, storage-ring, insertion-device, insertion

1592

Z. Patel, A. George, S. Milward, E.C.M. Rial, A.J. Rose, R.P. Walker, J.H. Williams
DLS, Oxfordshire, United Kingdom

2017 marks the tenth year of Diamond operation, during which time all insertion device straights have been filled. Diamond Light Source is a third generation, 3 GeV facility that boasts 29 installed insertion devices. Most room temperature devices have been designed, manufactured and measured in-house, and progress has been made in structure design and control systems to ensure new devices continue to meet stringent requirements placed upon them. The ‘completion' of the storage ring is not, however, the end of activity for the ID group at Diamond, as beamlines map out potential upgrade paths to Cryogenic Permanent Magnet Undulators (CPMUs) and SuperConducting Undulators (SCUs). This paper traces the progress of ID design at Diamond, and maps out future projects such as the upgrade to CPMUs and the challenges of designing a fixed-gap mini-wiggler to replace a sextupole in the main storage ring lattice.

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TUPAB117

Conceptual Design of a Novel SCAPE Undulator

photon, simulation, lattice, vacuum

1596

Y. Ivanyushenkov, J.F. Fuerst, E. Gluskin, Q.B. Hasse, M. Kasa, Y. Shiroyanagi, E. Trakhtenberg
ANL, Argonne, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
A concept of a novel SuperConducting Arbitrarily Polarizing Emitter, or SCAPE, has recently been suggested at the Advanced Photon Source. It consists of two pairs - both vertical and horizontal - of superconducting planar magnets assembled around a beam vacuum chamber. Such a device will be capable of generating either planar or circularly polarized photons, depending on which pair of magnets is energized. The magnetic simulation suggests that due to the employment of superconducting technology, the expected magnetic field is higher than that of the APPLE undulators. The SCAPE undulators could be useful for the fourth generation of storage rings with a multi-bend achromat lattice, as well as for the FELs where utilization of round beam vacuum chambers becomes possible. The results of magnetic modelling, as well as the design concept of the SCAPE, are presented.

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TUPAB122

Engineering Optimization of The Support Structure and Drive System for the LCLS-II Soft X-Ray Undulator Segments

photon, simulation, experiment, laser

1602

A.J. DeMello, D. Arbelaez, D. Bianculli, A.P. Brown, J.N. Corlett, J.R. Dougherty, D.E. Humphries, J.-Y. Jung, M. Leitner, S. Marks, K.A. McCombs, K.L. Ray, D.A. Sadlier, D. Schlueter, E.J. Wallén
LBNL, Berkeley, California, USA

Funding: Work supported by the Director, O'ce of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
The Linear Coherent Light Source II (LCLS-II) project, an upgrade to the free-electron laser facility at SLAC, is replacing the undulator system from a fixed gap to a variable gap system to enable tuning of the photon energy range. The LCLS-II project will include a soft x-ray (SXR) beam line and a hard x-ray (HXR) beam line. The SXR undulators are conventional vertical-gap horizontally-polarizing devices while the HXR undulators are novel horizontal-gap vertically-polarizing devices. This paper describes in detail the development of the SXR mechanical support structure and drive system. The effort has included extensive analysis of the various components to ensure that the undulators will perform within the design specifications. Engineering simulations undertaken and experiments performed to validate the computer modeling are presented together with measurement results from prototype and pre-production undulators.

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TUPAB123

Hard X-Ray and Soft X-Ray Undulator Segments for the Linear Coherent Light Source Upgrade (LCLS-II) Project

linac, photon, FEL, electron

1605

M. Leitner, D. Arbelaez, A.J. Band, D. Bianculli, A.P. Brown, J.N. Corlett, A.J. DeMello, J.R. Dougherty, L. Garcia Fajardo, K. Hanzel, M. Hoyt, D.E. Humphries, D. Jacobs, C. Joiner, J.-Y. Jung, D. Leitner, S. Marks, K.A. McCombs, D.V. Munson, K.L. Ray, D.A. Sadlier, J.J. Savino, D. Schlueter, E.J. Wallén, V. Waring, A. Zikmund
LBNL, Berkeley, California, USA
C.J. Andrews, D.E. Bruch, A.L. Callen, G. Janša, S. Jansson, K.R. Lauer, Yu.I. Levashov, D.S. Martinez-Galarce, B.D. McKee, H.-D. Nuhn, Â. Oven, M. Rowen, Z.R. Wolf
SLAC, Menlo Park, California, USA

Funding: Work supported by the Director Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
Stanford Linear Accelerator Laboratory is currently constructing the Linear Coherent Light Source II (LCLS-II), a free-electron laser (FEL) which will deliver x-rays at an energy range between 0.2 keV and 5 keV at high repetition rate of up to ~1 MHz using a new 4 GeV superconducting RF linac, and at and an energy range between 1 keV and 25 keV when driven by an existing copper linac at up to 120 Hz repetition rate. To cover the full photon energy range, LCLS-II includes two variable-gap, hybrid-permanent-magnet undulator lines: A soft x-ray undulator (SXR) line with 21 undulator segments optimized for a photon energy range from 0.2 keV to 1.3 keV plus a hard x-ray undulator (HXR) line with 32 undulator segments designed for a photon energy range from 1.0 keV to 25.0 keV. Lawrence Berkeley National Laboratory is responsible for fabricating the 53 undulator segments. This paper summarizes the main parameters and design attributes for both LCLS-II undulator segment types.

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TUPAB124

Development of the Manufacturing and QA Processes for the Magnetic Modules of the LCLS-II Soft X-Ray Undulators

simulation, status, laser, free-electron-laser

1609

K.L. Ray, D. Arbelaez, A.J. Band, D. Bianculli, A.P. Brown, J.N. Corlett, A.J. DeMello, J.R. Dougherty, L. Garcia Fajardo, K. Hanzel, D.E. Humphries, J.-Y. Jung, D. Leitner, M. Leitner, S. Marks, K.A. McCombs, D.V. Munson, D.A. Sadlier, D. Schlueter, E.J. Wallén, V. Waring, A. Zikmund
LBNL, Berkeley, California, USA
D.E. Bruch, A.L. Callen, G. Janša, D.S. Martinez-Galarce, H.-D. Nuhn, E. Ortiz, Â. Oven, M. Rowen, Z.R. Wolf
SLAC, Menlo Park, California, USA

Funding: Work supported by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
A new free electron laser being built at SLAC National Accelerator Laboratory, the Linear Coherent Light Source II (LCLS-II), will use 21 soft x-ray undulators (SXR) and 32 hard x-ray undulators (HGVPU). Lawrence Berkeley National Laboratory (LBNL) is responsible for the design and manufacturing of all variable-gap, hybrid permanent-magnet undulators. The physics requirements for the undulators specify a longitudinal pole misalignment maximum rms error of 25 μm and a vertical pole misalignment maximum error of 50 μm. In addition, magnet positioning critically influences the gap-dependent field properties due to saturation effects at the smallest operational gaps. This paper discusses the manufacturing and QA methods developed to carefully control the longitudinal and vertical pole and magnet positions during undulator production. Inspection results are discussed based on data gathered during construction of a prototype as well as pre-production soft x-ray undulator.

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TUPAB125

Magnetic Field Measurements at LBNL on Soft X-Ray and Hard X-Ray Undulator Segments for the Linear Coherent Light Source Upgrade (LCLS-II) Project

photon, linac, software, alignment

1612

E.J. Wallén, D. Arbelaez, J.N. Corlett, L. Fajrado, H.W. Kim, M. Leitner, S. Marks, D. Schlueter, A. Zikmund
LBNL, Berkeley, California, USA
Yu.I. Levashov, H.-D. Nuhn, Z.R. Wolf
SLAC, Menlo Park, California, USA

Funding: Work supported by the Director, O'ce of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
Stanford Linear Accelerator Laboratory is currently constructing the Linear Coherent Light Source II (LCLS-II), a FEL which will deliver x-rays at an energy range 0.2-5 keV at high repetition rate of up to 1 MHz using a new 4 GeV superconducting linac, and at an energy range 1-25 keV when using the existing copper linac at up to 120 Hz. To cover the full photon energy range, LCLS-II includes two variable-gap, hybrid-type permanent magnet undulator lines: A soft x-ray undulator (SXR) line with 21 undulator segments for the photon energy range 0.2-1.3 keV plus a hard x-ray undulator (HXR) line with 32 undulator segments designed for a photon energy range from 1-5 keV when using the superconducting linac. The HXR line is also designed to support 25 keV and higher photon energies when using the existing copper linac. Lawrence Berkeley National Laboratory (LBNL) is responsible for fabricating the undulators and tuning 23 of the HXR undulators. This paper summarizes the magnetic field measurements carried out on the pre-production undulators and describes the plans at LBNL for the magnetic measurements on the HXR undulators in series production.

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TUPAB133

Perturbation Analysis for Beam Trajectories. Determining Local Shielding Containment for LCLS-II

shielding, quadrupole, simulation, dipole

1637

M. Santana-Leitner
SLAC, Menlo Park, California, USA

Funding: Work supported by U.S. Department of Energy contract DE-AC02-76SF00515
Containment of beam losses by halo and momentum/energy collimators is a well-established practice for normal operation of particle accelerators where tracking codes are applied. However, for exceptional events, such as magnet power failures, severe lattice mis-match, etc., ad-hoc analytical approaches are typically applied. Oftentimes those simplified methods are not automatic; they don't define the full phase-space of mis-steered trajectories and cannot keep up with beam-line upgrades. Moreover, there may exist a disconnect between the teams analyzing consequences of errant beams and those involved in beam-line design. With electron beams exceeding 100 kW, design of LCLS-II at SLAC National Accelerator Laboratory required exhaustive beam-containment studies to avoid potential destruction of components and excessive dose rates. The geometry of the different beam-lines and the nominal optics was built with MadFLUKA [1], and FLUKA [2] Monte Carlo code along with perturbations to magnetic fields was used to inspect failures compatible with beam operations and hardware settings. Consequences of mis-steered rays and the respective mitigations were directly analyzed with FLUKA.
[1] M. Santana-Leitner et al., MadFLUKA Beam Line 3D Builder. Simulation of Beam Loss Propagation in Accelerators, IPAC14 proceedings, MOPME040
[2] A. Ferrari et al, The FLUKA Code: Developments and Challenges for High Energy and Medical Applications, Nuclear Data Sheets 120, 211-214 (2014)

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TUPAB134

Life Expectancy Studies for LCLS-II Permanent Magnet Undulators

radiation, permanent-magnet, electron, optics

1640

M. Santana-Leitner, D.E. Bruch, R.C. Field, D.S. Martinez-Galarce, B.D. McKee, H.-D. Nuhn, M. Rowen, S.W. Score
SLAC, Menlo Park, California, USA

Funding: Work supported by U.S. Department of Energy contract DE-AC02-76SF00515
LCLSII at SLAC National Accelerator Laboratory will add a 4 GeV superconducting Linac to the existing 20 GeV Cu structure. Electron beams from the two sources going through two new variable gap undulators [*] will produce FEL ranging 200-5000 keV at up to 929 kHz, also reaching 20 keV at low frequency. Such performance will be achieved by hybrid design undulators with NdFeB magnet blocks until radiation-induced demagnetization exceeds 0.01%. This is a sizable challenge, as LCLS-II will carry 120 kW beams in both its soft (SXR) and hard (HXR) beam-lines. Even small fractional losses could result excessive if too frequent or not detected and aborted fast enough. A model of SXR undulator was set for FLUKA [**] radiation transport, including segments, phase-shifters, quadrupoles, RFBPM, stands/pillars and interconnecting parts. Components were installed according to MAD files, which were also used to code the optics. Beam-loss/shower propagation was simulated for beam mis-steering, interception at wire scanners and gas-bremsstrahlung interactions. Results help set limits on shut-off times, uniform loss levels and wire scanner use, and to define placement for beam loss monitors.
* M. Leitner et al, Hard X-Ray and Soft X-Ray Undulator Segments for the Linear Coherent Light Source Upgrade (LCLS-II) Project, these proceedings
** A. Ferrari et al, The FLUKA Code: Developments and Challenges for High Energy and Medical Applications, Nuclear Data Sheets 120, 211-214 (2014)

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TUPAB135

A 1.75 mm Period RF-Driven Undulator

laser, electron, FEL, cavity

1643

F. Toufexis, S.G. Tantawi
SLAC, Menlo Park, California, USA

Funding: This project was funded by U.S. Department of Energy under Contract No. DE-AC02-76SF00515, and the National Science Foundation under Contract No. PHY-1415437.
To reduce the linac energy, and hence the size required for a Free Electron Laser radiating at a given wavelength, a smaller undulator period with sufficient field strength is needed. Previous work from our group successfully demonstrated a microwave undulator at 11.424 GHz using a corrugated cylindrical waveguide operating in the HE11 mode. Scaling down the undulator period using this technology poses the challenge of confining and coupling* the electromagnetic fields while maintaining over-moded features for power handling capability and electron beam wakefield mitigation. In this work, we present a novel end section of an RF undulator at 91.392 GHz. To confine the fields inside the undulator, a corrugated waveguide is connected through a matching section to a linear taper and a mirror. After the mirror, a Bragg reflector and a matching section are used to reflect back all the fields leaking out of the mirror opening.
* F. Toufexis, J. Neilson, and S.G. Tantawi, Coupling and Polarization Control in a mm-wave Undulator, these proceedings.

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TUPAB136

Coupling and Polarization Control in a mm-wave Undulator

polarization, coupling, controls, electron

1647

F. Toufexis, J. Neilson, S.G. Tantawi
SLAC, Menlo Park, California, USA

Funding: This project was funded by U.S. Department of Energy under Contract No. DE-AC02-76SF00515, and the National Science Foundation under Contract No. PHY-1415437.
To reduce the linac energy required for an FEL radiating at a given wavelength, and hence its size, a smaller undulator period with sufficient field strength is needed. Previous work from our group successfully demonstrated a microwave undulator at 11.424 GHz using a corrugated cylindrical waveguide operating in the HE11 mode. Scaling down the undulator period using this technology poses the challenge of confining and coupling the electromagnetic fields while maintaining overmoded features for power handling capability and electron beam wakefield mitigation. We have designed a mm-wave undulator cavity at 91.392 GHz*. This undulator requires approximately 1.4 MW for sub-microsecond pulses to generate an equivalent K value of 0.1. Transferring such amounts of power in mm-wave frequencies requires overmoded corrugated waveguides, and coupling through irises creates excessive pulsed heating. We have designed a novel mode launcher that allows coupling power from a highly overmoded corrugated waveguide to the undulator through the beam pipe. Additionally, this mode launcher can be used along with grating polarizers to control the polarization of the produced light.
* F. Toufexis and S.G. Tantawi, A 1.75 mm Period RF-Driven Undulator, these proceedings.

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TUPAB140

Analysis and Correction of in-Vacuum Undulator Misalignment Effects in a Storage Ring Synchrotron Radiation Source

electron, alignment, radiation, storage-ring

1663

O.V. Chubar, T.A. Caswell, Y. Chen-Wiegart, A. Fluerasu, Y. Hidaka, D.A. Hidas, C.A. Kitegi, M.S. Rakitin, T. Tanabe, J. Thieme, L. Wiegart, G. Williams
BNL, Upton, Long Island, New York, USA

Funding: Work was partially supported by US DOE SBIR grants DE-SC0006284 and DE-SC0011237.
In-vacuum undulators (IVU) are currently very extensively used at different light source facilities, and in particular in medium-energy storage rings, for the production of high-brightness and high-flux hard X-rays. The relatively small (~5 mm or less) vertical magnetic gaps used in these planar undulators make them, however, rather sensitive to the accuracy of alignment of magnet arrays with respect to electron orbit in the vertical plane. Based on results of commissioning of a number of IVUs at hard X-ray beamlines of NSLS-II, their eventual misalignment with respect to the electron orbit was found to be among frequent reasons of spectral underperformance of the beamlines. We will present results of simulations of different IVU misalignment effects on magnetic fields seen by electron beam and on the emitted undulator radiation spectra. The simulations show e.g. that an impact of angular misalignment of an IVU on the radiation spectrum can be minimized if the IVU elevation is selected to make the electron orbit to pass through the IVU magnetic center. Experimental results of spectrum-based alignment of IVUs at hard X-ray beamlines will be presented.

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TUPAB146

Vibration Measurements of Super-Conducting Undulator at SSRF

data-analysis, data-acquisition, experiment, damping

1675

R.B. Deng, Y. Liu, L. Wang, S. Xiang
SINAP, Shanghai, People's Republic of China

Funding: Work supported by the National Natural Science Foundation of China (Grant No. 11405255)
A Super-Conducting Undulator (SCU) is being built at SSRF. Mechanical stability of SCU is critical to beam stability since the central load is supported by special strings in SCU and the vibration of load will cause directly the vibration of beam. In this paper, vibration results of several key components including central load, cold head, frame support, etc, are studied under different working mode of compressors. The ground vibrations at different distances are compared to get the influence of compressors to SCU. Useful suggestions and possible measures are described to mitigate the vibration and improve SCU stability.

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TUPIK003

Electron Transport on COXINEL Beam Line

electron, laser, free-electron-laser, FEL

1688

T. André, I.A. Andriyash, F. Blache, F. Bouvet, F. Briquez, M.-E. Couprie, Y. Dietrich, J.P. Duval, M. El Ajjouri, A.M. Ghaith, C. Herbeaux, N. Hubert, M. Khojoyan, M. Labat, N. Leclercq, A. Lestrade, A. Loulergue, O. Marcouillé, F. Marteau, P. N'gotta, P. Rommeluère, K.T. Tavakoli, M. Valléau
SOLEIL, Gif-sur-Yvette, France
S. Bielawski, C. Evain, C. Szwaj
PhLAM/CERLA, Villeneuve d'Ascq, France
S. Corde, J. Gautier, J.-P. Goddet, G. Lambert, B. Mahieu, V. Malka, S. Smartzev, C. Thaury
LOA, Palaiseau, France
E. Roussel
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

COXINEL experiment aims at demonstrating free electron laser (FEL) amplification with a laser plasma accelerator (LPA). For COXINEL, a dedicated 8 m transport line has been designed and prepared at SOLEIL. We present here LPA beam transport results around 180 MeV through this line. Different electron beam optics were applied.

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TUPIK106

Analysis of the Synchrotron Radiation from Segmented Undulator in Double-Mini Beta Function

radiation, brilliance, electron, photon

1964

H.W. Luo, C.H. Lee
NTHU, Hsinchu, Taiwan
T.Y. Chung, C.-S. Hwang
NSRRC, Hsinchu, Taiwan
C.-S. Hwang
NCTU, Hsinchu, Taiwan

Three long straight sections with double-mini beta-y lattice were created in the Taiwan Photon Source (TPS) for which the effects of focusing elements and phase shifters between the collinear undulators result in incorrect calculations of the brilliance while assuming a Gaussian-approximation. Therefore, an on-axis Wigner distribution function (WDF), which includes effects of wave phenomena, is a natural way to measure the intensity of synchrotron radiation and is used in this article as the definition of brilliance.

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TUPIK108

Beam Based Alignment Studies for the CLARA FEL Test Facility

FEL, quadrupole, alignment, cavity

1971

J.K. Jones, N. Thompson
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

The CLARA (Compact Linear Accelerator for Research and Applications) test facility is designed to experimentally demonstrate innovative FEL schemes for future light source applications. Such schemes can place strict requirements on the accelerator beam properties as well as the relative alignment of the beam in the FEL radiators and modulators. Beam-based alignment (BBA) of the FEL section is therefore an operational requirement for all advanced FEL facilities. In this paper we demonstrate results of CLARA BBA simulations, and also report initial simulation results from the use of non-linear algorithms to optimise the FEL performance directly.

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WEOCA3

Status of the Development of Superconducting Undulators at the Advanced Photon Source

photon, vacuum, FEL, storage-ring

2499

Y. Ivanyushenkov, C.L. Doose, J.F. Fuerst, E. Gluskin, Q.B. Hasse, M. Kasa, Y. Shiroyanagi
ANL, Argonne, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357
Superconducting planar undulator (SCU) technology has been developed and is currently in use at the Advanced Photon Source (APS). The experience of building and operating the first short-length, 16-mm period superconducting undulator, SCU0, paved the way for two 1-m long, 18-mm period devices, SCU18-1 and SCU18-2. The first of those undulators has been in operation since May 2015, while the second one replaced SCU0 in September 2016. The possibility of building planar SCUs with a high quality field has been demonstrated at the APS. The measured phase errors of SCU18-2 at the design operational current are only 2 degrees rms, for example. An FEL SCU prototype - a 1.5-m long, 21-mm period undulator - was also built and tested as part of an LCLS SCU R&D program. This undulator successfully achieved all LCLS-II undulator requirements including a phase error of 5 degrees rms. The superconducting undulator technology also allows the fabrication of circular polarizing devices. Currently, a new helical SCU is under construction at the APS. In addition, the concept of a novel Superconducting Arbitrarily Polarizing Emitter, or SCAPE, has been suggested and is now under development.

Slides WEOCA3 [2.826 MB]

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WEPAB001

Parallel Operation of SASE1 and SASE3 Undulator Sections of European XFEL

radiation, simulation, kicker, operation

2554

A. Sargsyan, V. Sahakyan
CANDLE SRI, Yerevan, Armenia
W. Decking
DESY, Hamburg, Germany

In the current paper the numerical simulation results for parallel (decoupled) operation of SASE1 and SASE3 undulator sections of European XFEL are presented. The study was based on the idea of betatron switcher imple-mentation. It was shown that it is possible to avoid energy spread growth in SASE1 and to reach the saturation in SASE3 in desirable range of radiation wavelengths by a trajectory kick before SASE1 and its correction before SASE3.

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WEPAB004

Progress Status for the 10 Year Old SOLEIL Synchrotron Radiation Facility

operation, injection, storage-ring, booster

2564

L.S. Nadolski, Y.-M. Abiven, P. Brunelle, A. Buteau, N. Béchu, M.-E. Couprie, X. Delétoille, J.M. Dubuisson, C. Herbeaux, N. Hubert, M. Labat, J.-F. Lamarre, P. Lebasque, A. Lestrade, A. Loulergue, M. Louvet, P. Marchand, O. Marcouillé, F. Marteau, A. Nadji, R. Nagaoka, F. Ribeiro, K.T. Tavakoli, M.-A. Tordeux
SOLEIL, Gif-sur-Yvette, France

Synchrotron SOLEIL has just turned 10 years since its commissioning. The 2.75 GeV facility is now delivering very stable photon beams to 29 beam lines. A total of 5 operation modes are available in top-up. Maintaining and updating the key performance metric remains a daily work facing both aging of components and tighter operation requirements. Low-alpha operation is attracting more beam lines leading us to an upgrade of the Booster (BOO) radiofrequency (RF) system in order to increase the injection efficiency into the storage ring (SR). The femtoslicing experiment is now in production for a hard X-ray beam line; a dedicated chicane has been installed for a second beam line in the soft X-ray regime. The two long canted beam lines can operate simultaneously at minimum gaps since May 2016 thanks to the introduction of a dedicated photon absorber and a fast angle interlock. R&D work in several areas will be reported. In parallel lattice design are in progress both for short term and long term evolution of the ring performance.

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WEPAB009

Pilot Experiments and New Developments at the DELTA Short-Pulse Facility

laser, electron, radiation, experiment

2578

S. Khan, B. Büsing, F. Götz, M.A. Jebramcik, N.M. Lockmann, C. Mai, A. Meyer auf der Heide, R. Niemczyk, B. Riemann, G. Shayeganrad, M. Suski, P. Ungelenk, D. Zimmermann
DELTA, Dortmund, Germany
U. Bovensiepen, S. Döring, A. Eschenlohr, M. Ligges, L. Plucinski, M. Plötzing, C.M. Schneider, S. Xiao
Universität Duisburg-Essen, Duisburg, Germany
S. Cramm
Forschungszentrum Jülich, Peter-Gruenberg-Institut-6, Jülich, Germany
M. Gehlmann
Forschungszentrum Jülich, Peter Gruenberg Institut, Jülich, Germany

Funding: BMBF 05K16PEA, BMBF 05K16PEB, Mercur Pr-2014-0047
At the 1.5-GeV synchrotron light source DELTA operated by the TU Dortmund University, ultrashort radiation pulses in the vacuum ultraviolet (VUV) and terahertz (THz) regime are routinely generated by the interaction of electron bunches with femtosecond laser pulses. A laser-induced energy modulation is converted into a density modulation (microbunching) by a magnetic chicane, leading to coherent emission at harmonics of the initial laser wavelength (coherent harmonic generation, CHG). Path length differences of the energy-modulated electrons along the magnetic lattice lead to a dip in the longitudinal charge distribution, which gives rise to the coherent emission of THz radiation. In first pump-probe photoemission experiments, the spatial and temporal overlap of laser pump and CHG probe pulse on the sample was demonstrated. Furthermore, the effect of two temporally separated seed pulses was studied in the VUV and (sub-)THz regime.

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WEPAB010

Progress Towards an EEHG-Based Short-Pulse Source at DELTA

electron, laser, radiation, synchrotron

2582

A. Meyer auf der Heide, F.H. Bahnsen, B. Büsing, F. Götz, S. Hilbrich, M.A. Jebramcik, S. Khan, N.M. Lockmann, C. Mai, R. Niemczyk, B. Riemann, G. Shayeganrad, M. Suski, P. Ungelenk, D. Zimmermann
DELTA, Dortmund, Germany

Funding: Work supported by the accelerator initiative (ARD) of the Helmholtz society, BMBF 05K13PE3, BMBF 05K16PEA.
The short-pulse source at the 1.5-GeV synchrotron light source DELTA, operated by the TU Dortmund University, enables the generation of sub-ps radiation pulses in the VUV regime based on coherent harmonic generation (CHG). As an upgrade, the employment of echo-enabled harmonic generation (EEHG) is planned which allows to produce shorter wavelengths. Recent developments and measurements regarding the twofold energy modulation required for EEHG are presented.

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WEPAB017

Generation of Ultra-Short Electron Bunches and FEL Pulses and Characterization of Their Longitudinal Properties at FLASH2

electron, FEL, operation, laser

2600

F. Christie, J. Rönsch-Schulenburg, S. Schreiber, M. Vogt
DESY, Hamburg, Germany

The free-electron laser in Hamburg (FLASH) is a user facility, delivering soft X-ray radiation, consisting of two beam lines, FLASH1 and FLASH2. The injector and the main linac are shared between both beam lines. Starting in 2014, FLASH2 has been commissioned for user operation. Currently, there is no hardware installed for the direct measurement of the electron bunch length nor the photon pulse duration at FLASH2. Exact knowledge of the pulse duration is essential for time-resolved user experiments performed at FLASH. Therefore, we are designing a modified beam line, containing a new type of X-band deflecting cavity* and a dipole, downstream of the FLASH2 undulator, to map the longitudinal phase space onto a beam screen. Anticipating the feasibility of measuring the longitudinal phase space with high resolution, a study on optimizing the free-electron laser (FEL) performance for shortest bunches is ongoing.
*B. Marchetti et al., X-Band TDS project, contribution to these conference proceedings

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WEPAB019

Concept for a Seeded FEL at FLASH2

FEL, electron, laser, free-electron-laser

2607

C. Lechner, R.W. Aßmann, J. Bödewadt, M. Dohlus, N. Ekanayake, B. Faatz, G. Feng, I. Hartl, T. Laarmann, T. Lang, L. Winkelmann, I. Zagorodnov
DESY, Hamburg, Germany
A. Azima, M. Drescher, Th. Maltezopoulos, T. Plath, J. Roßbach, W. Wurth
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
S. Khan
DELTA, Dortmund, Germany

The free-electron laser (FEL) FLASH is a user facility delivering photon pulses down to 4 nm wavelength. Recently, the second FEL undulator beamline 'FLASH2' was added to the facility. Operating in self-amplified spontaneous emission (SASE) mode, the exponential amplification process is initiated by shot noise of the electron bunch, resulting in photon pulses of limited temporal coherence. In seeded FELs, the FEL process is initiated by coherent seed radiation, improving the longitudinal coherence of the generated photon pulses. The conceptual design of a possible seeding option for the FLASH2 beamline foresees the installation of the hardware needed for high-gain harmonic generation (HGHG) seeding upstream of the already existing undulator system. In this contribution, we present the beamline design and numerical simulations of the seeded FEL.

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WEPAB020

Beam Loss Simulations for the Implementation of the Hard X-Ray Self-Seeding System at European XFEL

electron, simulation, collimation, neutron

2611

S. Liu, W. Decking, L. Fröhlich
DESY, Hamburg, Germany

The European XFEL is designed to be operated with a nominal beam energy of 17.5 GeV at a maximum repetition rate of 27000 bunches/second. The high repetition rate together with the high loss sensitivity of the undulators raises serious radiation damage concern, especially for the implementation of the Hard X-ray Self-Seeding (HXRSS) system, where a 100 um thick diamond crystal will be inserted close to the beam in the undulator section. Since the seeding power level highly depends on the delay of the electron beam with respect to the photon beam, it is crucial to define the minimum electron beam offset to the edge of the crystal in the HXRSS chicane. At European XFEL a ~200 m long post-linac collimation section has been designed to protect the undulators. In the HXRSS scheme, however, beam halo hitting the crystal can generate additional radiation. Particle tracking simulations have been performed using GEANT4 and BDSIM for the undulator and the collimation section, respectively. The critical number of electrons allowed to hit the crystal is estimated for a certain operation mode and the efficiency of beam halo collimation is investigated to predict the minimum HXRSS chicane delay.

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WEPAB021

Experience with Multi-Beam and Multi-Beamline FEL-Operation

laser, experiment, operation, FEL

2615

J. Rönsch-Schulenburg, B. Faatz, K. Honkavaara, M. Kuhlmann, S. Schreiber, R. Treusch, M. Vogt
DESY, Hamburg, Germany

DESY's free-electron laser FLASH provides soft X-ray pulses for scientific users at wavelengths down to 4 nm simultaneously in two undulator beamlines. They are driven by a common linear superconducting accelerator with a beam energy of up to 1.25 GeV. The superconducting technology allows the acceleration of electron bunch trains of several hundred bunches with a spacing of 1 microsecond or more and a repetition rate of 10 Hz. A fast kicker-septum system directs one part of the bunch train to FLASH1 and the other part to FLASH2 keeping the full 10 Hz repetition rate for both. The unique setup of FLASH allows independent FEL pulse parameters for both beamlines. In April 2016, simultaneous operation of FLASH1 and FLASH2 for external users started. This paper reports on our operating experience with this type of multi-beam, multi-beamline set-up.

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WEPAB022

Background-free Harmonic Production in XFELs via a Reverse Undulator Taper

FEL, background, radiation, electron

2618

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

Nonlinear harmonics in X-ray FELs can be parasitically produced as soon as FEL reaches saturation, or can be radiated in dedicated afterburners. In both cases there is a strong background at the fundamental, since it is much stronger than harmonics. One can get around this problem by application of the recently proposed reverse undulator tapering. In this contribution we present numerical simulations of harmonic production in such a configuration as well as recent results from FLASH where the second and the third harmonics were efficiently generated with a low background at the fundamental. We also present the results for a high-contrast operation when the afterburner is tuned to the fundamental.

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WEPAB023

First Operation of a Harmonic Lasing Self-Seeded FEL

FEL, electron, operation, brightness

2621

E. Schneidmiller, B. Faatz, M. Kuhlmann, J. Rönsch-Schulenburg, S. Schreiber, M. Tischer, M.V. Yurkov
DESY, Hamburg, Germany

Harmonic lasing is a perspective mode of operation of X-ray FEL user facilities that allows to provide brilliant beams of higher energy photons for user experiments. Another useful application of harmonic lasing is so called Harmonic Lasing Self-Seeded Free Electron Laser (HLSS FEL) that allows to improve spectral brightness of these facilities. In the past, harmonic lasing has been demonstrated in the FEL oscillators in infrared and visible wavelength ranges, but not in high-gain FELs and not at short wavelengths. In this paper we report on the first evidence of the harmonic lasing and the first operation of the HLSS FEL at the soft X-ray FEL user facility FLASH in the wavelength range between 4.5 nm and 15 nm. Spectral brightness was improved in comparison with Self-Amplified Spontaneous emission (SASE) FEL by a factor of six in the exponential gain regime. A better performance of HLSS FEL with respect to SASE FEL in the post-saturation regime with a tapered undulator was observed as well. The first demonstration of harmonic lasing in a high-gain FEL and at a short wavelength paves the way for a variety of applications of this new operation mode in X-ray FELs.

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WEPAB024

Commissioning and First Heating with the European XFEL Laser Heater

laser, electron, cathode, FEL

2625

M. Hamberg
Uppsala University, Uppsala, Sweden
F. Brinker, M. Scholz
DESY, Hamburg, Germany

Funding: We thank DESY and Swedish research council under Project number DNR-828-2008-1093 for financial support.
The Laser Heater of the European XFEL has been installed and commissioning is in progress. We discuss the setup and the results of the first electron beam heating in the injector section.

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WEPAB027

Frequency Doubler and Two-color Mode of Operation at Free Electron Laser FLASH2

radiation, electron, operation, FEL

2635

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

We report on the results of the first operation of a frequency doubler at free electron laser FLASH2. The scheme uses the feature of the variable gap undulator. Undulator is divided in two parts. The second part of the undulator is tuned to the double frequency of the first part. Amplification process in the first undulator part is stopped at the onset of the nonlinear regime, such that nonlinear higher harmonic bunching in the electron beam density becomes pronouncing, but the radiation level is still small to disturb the electron beam significantly. Modulated electron beam enters the second part of the undulator and generates radiation at the 2nd harmonic. Frequency doubler allows operation in a two-color mode and operation at shorter wavelengths with respect to standard SASE scheme. Tuning of the electron beam trajectory, phase shifters and compression allows to tune intensities of the first and the second harmonic. The shortest wavelength of 3.1 nm (photon energy 400 eV) has been achieved with frequency doubler scheme, which is significantly below the design value for the standard SASE option.

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WEPAB029

Optimum Undulator Tapering of SASE FEL: From the Theory to Experiment

electron, FEL, radiation, laser

2639

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

Optimization of the amplification process in FEL amplifier with diffraction effects taken into account results in a specific law of the undulator tapering [*]. It is a smooth function with quadratic behavior in the beginning of the tapering section which transforms to a linear behavior for a long undulator. In practice, undulator consists of a sequence of modules of fixed length separated with intersections. Two modes of undulator tapering can be implemented: step tapering, and smooth tapering. Procedure of the step tapering applies step change of the undulator gap from module to module, and smooth tapering assumes additional linear change of the gap along each module. In this report we simulate the performance of the both experimental options and compare with theoretical limit.
[*] E.A. Schneidmiller and M.V. Yurkov, Optimization of a high efficiency free electron laser amplifier, Phys. Rev. ST Accel. Beams 18 (2015) 030705.

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WEPAB032

A Novel Optical Beam Concept for Producing Coherent Synchrotron Radiation with Large Energy Spread Beams

radiation, laser, electron, photon

2646

R. Rossmanith, A. Bernhard, V. Saile, P. Wesolowski
KIT, Karlsruhe, Germany
R.W. Aßmann, U. Dorda, B. Marchetti
DESY, Hamburg, Germany

Up to now two FEL concepts are known in conventional accelerators: 1.) In THz lasers an off-crest cavity adds a chirp to the bunch followed by a bunch compressor. Particles with different energies travel on different trajectories to the radiator. 2.) For EUV and X-ray FELs the beam enters an undulator which produces microbunches which then radiate. In this paper it is proposed to copy the THz laser scheme for EUV lasers. The incoming beam is chirped and a dogleg forces afterwards the particles with different energies to move on different parallel trajectories. Considering a detector plane perpendicular to the trajectories the particles with different energies arrive in general at different times. When in this plane for instance a TGU (Transverse Gradient Undulator) is positioned the emitted radiation in the TGU is monochromatic. If in addition chirp and dogleg are selected in such a way that the particles with different energies arrive at the same time at the entrance of the TGU the radiation is monochromatic and coherent similar to the THz laser concept.

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WEPAB035

Elettra Status Present Upgrades and Plans

operation, controls, photon, storage-ring

2657

E. Karantzoulis, A. Carniel, M. Cautero, B. Diviacco, S. Krecic, R. Visintini
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

The operational status of the Italian 2.4/2.0 GeV third generation light source Elettra is presented together with an account of some present upgrades and plans for the near future.

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WEPAB041

Status Report of Hiroshima Synchrotron Radiation Center Hiroshima University

synchrotron, synchrotron-radiation, radiation, photon

2672

S. Matsuba, K. Goto, K. Kawase
HSRC, Higashi-Hiroshima, Japan

The Hiroshima Synchrotron Radiation Center (HSRC) at Hiroshima University was established in 1996 for the research of solid state physics. The HSRC equips a 700 MeV electron storage ring nicknamed HiSOR. Recently, we are considering upgrade of the instrumentation beamline for the optical monitoring. In this paper, we report the present status of HSRC.

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WEPAB047

Concept of a New Generation Synchrotron Radiation Facility KEK Light Source

lattice, cavity, emittance, brightness

2687

T. Honda
KEK, Ibaraki, Japan

KEK has proposed a new SR facility: KEK Light Source (KEK-LS) towards the completion of the first half of the 2020s. The energy and the natural horizontal emittance are 3 GeV and 0.13 nm rad, respectively. To mitigate the intra-beam scattering effect, we are planning to install third harmonic RF cavities. The extremely low emittance ring has been designed based on the Hybrid Multi-Bend Achromatic (HMBA) lattice, which was originally developed at the ESRF upgrade project. We have modified it to insert a short straight section at the center of the unit cell. The number of unit cells is 20, and the circumference is about 570 m. Except for an RF section and an injection section, the ring can accommodate 18 undulators in the long straight sections of 5.6 m, and the additional 20 short straight section of 1.2 m will be used for short-period narrow-gap undulators. If we assume an undulator of the magnetic period 20 mm, total length 5.0 m, and the smallest gap 4 mm, the SR brightness approaches 10²² Photons/mrad²/mm²/s/0.1%B.W. at the X-ray range. It has a high coherent fraction of about 20% at the diffraction limit wavelength 0.32 keV.

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WEPAB058

Commissioning Status of the Dalian Cohernet Light Source

FEL, laser, electron, linac

2709

G.L. Wang
DICP, Dalian, People's Republic of China

The Dalian Coherent Light Source (DCLS) is a seeded FEL user facility working at 50-150 nm, now under commissioning in Dalian, China. The facility consists of a 300 MeV normal-conducting S-band linear accelerator (LINAC) and two undulator beamlines. The first beam-line (FEL-1) will provide picosecond FEL radiation with the pulse energy up to several hundreds micro-joule, the second beam-line (FEL-2) will be a femtosecond and polarization FEL. The LINAC and FEL-1 beam-line construction was complete by the summer of 2016, the installation of FEL-2 is in preparation. High power RF conditioning of the LINAC started in August 2016 and the beam commissioning initiated 3 months later. This article describes the commissioning status of DCLS, reports on the goals achieved so far.

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WEPAB065

Proposal for the Generation of Terawatt, Attosecond X-Ray Pulses in Free Electron Lasers

radiation, laser, electron, FEL

2723

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

A feasible novel method is proposed to generate attosecond terawatt X-ray radiation pulse in free electron lasers, which could find its application on multiple science fields. In our scheme, a chirped laser is employed to generate a chirped periodic current enhancement and a series of spatiotemporal shifters are applied between the undulator sections to generate ultra-short radiation pulse. Three-dimensional start-to-end simulations are carried out and the calculation results show that a 0.15nm X-ray pulse with the peak power of about 1TW and the pulse length of 0.1fs could be achieved in our scheme.

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WEPAB072

Apple II Undulator and Front End Design for the New LOREA Beamline at ALBA

polarization, vacuum, dipole, wiggler

2747

J. Campmany, L.G.O. Garcia-Orta, J. Marcos, V. Massana
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain

ALBA synchrotron has started the construction of a new beamline LOREA, for Low-Energy Ultra-High-Resolution Angular Photoemission for Complex Materials. It will operate in the range of 10 to 1500 eV and will use polarized light. In order to produce the light to be used in this beamline, several options have been studied, and finally an Apple II design has been chosen. The device can operate as an undulator at low energies and as a wiggler at high energies, reaching a wide energy range. The high demanding characteristics of the beamline in terms of energies lead to a device providing high power and wide beam in some working modes. This situation has been a challenge for the Front End design, especially for the vertically polarized mode, with some changes with respect to standard ALBA front ends. In this paper we present the magnetic design and expected performances of the device, that currently is being built by KYMA, as well as the Front End design, that currently is being built by RMP and TVP.

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WEPAB074

On the Coherence Properties of FEL

FEL, laser, simulation, experiment

2753

M.A. Pop, F. Curbis, S. Werin
MAX IV Laboratory, Lund University, Lund, Sweden

Free Electron Lasers (FEL) are one of the most brilliant light sources in the world and their unique properties are driving worldwide research in understanding and improving them. Numerous papers have already been published describing the output of the FEL in terms of coherence and bandwidth. In this contribution, however, we focus on how the coherence evolves along the FEL undulator and on what factors influence it the most. Using Genesis⁻¹.3* we have been able to follow and record the light field as it is being produced in the undulator. Our analysis method takes advantage of the extensively studied double pinhole experiment and uses the principles behind it to create a tool for extracting coherence information from the radiation field. We will present the scope, limitations and advantages of these virtual experiments as well as an application on an example FEL, to showcase what kind of information can be extracted using this method.
* Numerical simulation code used for particle and field distribution tracking along the undulator developed by Sven Reiche

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WEPAB077

The Soft X-Ray Laser Project at MAX IV

laser, FEL, electron, linac

2760

S. Werin, J. Andersen, F. Curbis, L. Isaksson, M. Kotur, F. Lindau, E. Mansten, D. Olsson, H. Tarawneh, P.F. Tavares, S. Thorin
MAX IV Laboratory, Lund University, Lund, Sweden
S. Bonetti, A. Nilsson
Stockholm University, Stockholm, Sweden
V.A. Goryashko
Uppsala University, Uppsala, Sweden
P. Johnsson
Lund University, Lund, Sweden
M. Larsson, P. Salén
FYSIKUM, AlbaNova, Stockholm University, Stockholm, Sweden
O. Tjernberg
KTH Physics, Stockholm, Sweden

A soft x-ray laser beamline utilising FEL technology is being designed for the Short Pulse Facility (SPF) at the MAX IV Laboratory. A conceptual design study has been started following on the scientific case already prepared in collaboration between several Swedish Universities and driven by a strong (Swedish) user demand [*]. The baseline goal of the SXL beamline is to generate intense and short pulses in the range 1-5 nm (1-0.2 keV). The system is building on the MAX IV linac system, already today providing 3 GeV and pulses compressed to 100 fs for other applications within the SPF. As a special feature we foresee a variety of pump-probe capabilities. We here describe design issues and solutions for the accelerator and FEL system.
* http://frielektronlaser.se/onewebmedia/SXL_science_case₁61102.pdf

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WEPAB083

Development of Linac-Based MIR/THz FEL Facility and Photocathode RF-gun in Thailand

electron, FEL, laser, gun

2763

K. Buakor, N. Chaisueb, K. Damminsek, S. Rimjaem, J. Saisut, C. Thongbai, W. Thongpakdi
Chiang Mai University, Chiang Mai, Thailand

A linac-based MIR/THz free-electron laser facility is under the development at the Plasma and Beam Physics Research Facility, Chiang Mai University. The ultimate goal of the project is to generate the infrared radiation covering the wavelengths from 13 to 125 μm. The main applications of the radiation involved MIR/THz imaging and spectroscopy. The future FEL facility will consists of an injector system, an experimental station for coherent transition radiation, two magnetic bunch compressors and two undulator magnets equipped with optical cavities for MIR and THz beamlines. An expected electron beam energy is between 10 to 20 MeV with an energy spread of about or less than 1 %. Two undulator magnets with maximum undulator parameters of 1 and 0.95 will be used for generation of the THz-FEL and MIR-FEL, respectively. In this paper, we present the status of the design and construction of this future FEL facility.

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WEPAB084

Development of Injector System for MIR/THz Free-Electron Laser Facility in Thailand

electron, gun, simulation, FEL

2767

W. Thongpakdi, S. Rimjaem
Chiang Mai University, Chiang Mai, Thailand

Development of a linac-based MIR/THz FEL light source is ongoing at the Plasma and Beam Physics Research Facility, Chiang Mai University. The future facility will consist of an S-band thermionic cathode RF electron gun, a pre-magnetic bunch compressor in a form of alpha magnet, an S-band travelling-wave linac structure, a 180-degree achromat system and two undulator magnets equipped with optical cavities. This research focuses on start-to-end beam dynamics simulations of the injector system. The aim of the study is to produce high quality electron beam at the entrance of the THz undulator magnet. The simulation was conducted by using programs PARMELA and ELEGANT. The program PARMELA was utilized to study the electron beam dynamics inside the RF-gun. Then, the program ELEGANT was used to optimize the injector system parameters. Optimization of physical specifications for the achromat system was performed to obtain short electron bunches with small energy spread at the undulator entrance. In this paper, results of beam dynamics simulations with suitable condition for the THz-FEL beamline are presented and discussed.

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WEPAB086

Design and Optimisation of SPS-II Storage Ring

emittance, lattice, dipole, dynamic-aperture

2773

P. Klysubun, T. Pulampong, P. Sudmuang
SLRI, Nakhon Ratchasima, Thailand

Siam Photon Source (SPS) in Thailand has been operating and providing synchrotron radiation to users for more than a decade, leading to growing user community in South East Asia region. This gives rise to the possibility of constructing a new 3 GeV light source which could provide synchrotron light with higher photon energy and higher brilliance than the existing 1.2 GeV machine. Hybrid multi-bend achromat (HMBA) lattice design providing small natural beam emittance is a promising choice. In this paper, the Double-Triple Bend Achromat (DTBA) design with extra straight section scaled from Diamond Light Source upgrade lattice [ref.] is presented. Lattice optimisation with simplified magnet specifications still allows natural emittance of about 900 pm'rad for a 321.3 m circumference ring with sufficient dynamic aperture.

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WEPAB090

Developments in the CLARA FEL Test Facility Accelerator Design and Simulations

FEL, laser, simulation, optics

2787

P.H. Williams, D.J. Dunning, N. Thompson
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, 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. The requirement to co-propagate the beam with laser seeds of very different wavelengths has led to a redesign of the section preceding the undulators, with a dogleg being replaced by a chicane. Additional refinements of the facility design include the inter-undulator sections. With this finalised design we show start to FEL simulations for all beam modes envisaged.

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WEPAB097

Modelling Two-Colour FEL with Wide Wavelength Separation and Individual Polarisation Tuning

polarization, FEL, simulation, electron

2808

D. Bultrini, N. Thompson
Cockcroft Institute, Warrington, Cheshire, United Kingdom
R.J. Allan
The Hartree Centre, Science and Technology Facilities Council (STFC/DL), Warrington, United Kingdom
L.T. Campbell, B.W.J. MᶜNeil
USTRAT/SUPA, Glasgow, United Kingdom
D.J. Dunning, N. Thompson
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
J.D.A. Smith
TXUK, Warrington, United Kingdom

Free electron lasers (FELs) are currently enabling cutting edge research in chemistry, biology and physics. We use simulations to assess a new FEL capability that would add to the impressive repertoire of experiments made possible by the technology: a two-colour independent polarization mode, which allows for light pulses with variable temporal separation, individually tuneable polarisation, and widely separated wavelength. Simulations are carried out using the broad bandwidth FEL code Puffin, the results of which are used to discuss the radiation properties of the output. This scheme is applicable to existing and proposed facilities which feature undulators with variable ellipticity and gap.

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WEPAB098

Dielectrically-Loaded Waveguide as a Microwave Undulator for High Brillance X-Rays at 45 - 90 Kev

brightness, photon, operation, coupling

2812

R. Kustom, A. Nassiri, G.J. Waldschmidt
ANL, Argonne, Illinois, USA

The HEM12 mode in a cylindrical, dielectrically-loaded waveguide provides E and H fields on the central axis that are significantly higher than the fields on the conducting walls. This structure, operating near the cutoff frequency of the HEM12 mode, spans a frequency range where the wavelength and phase velocity vary significantly. This property can be exploited to generate undulator action with short periods for the generation of high brightness x-rays. The frequency range of interest would be from 18 to 34.5-GHz. The goal would be to generate x-rays on the fundamental mode over a range of 45 to 90-kev. The tunability would be achieved by changing the source frequency while maintaining a constant on-axis equivalent undulator field strength of 0.5-T.

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WEPAB109

Multipole Field Effects in a Transverse Gradient Undulator

multipole, FEL, electron, simulation

2833

P. Baxevanis, Z. Huang
SLAC, Menlo Park, California, USA

Using a transverse gradient undulator (TGU) is one of the methods proposed in order to enable the utilization of electron beams with large energy spread (such as those from plasma-based accelerators) in a free-electron laser (FEL). Most of the analytical treatments of this scheme assume a linear variation of the undulator field with one of the transverse coordinates. While this assumption leads to a simplified and more tractable model, including higher-order multipoles allows us to offer a more complete and rigorous description of the system. In this paper, we investigate the magnetic field components of a TGU using both theory and simulation and explore the impact of higher-order multipoles on the FEL performance.

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WEPAB118

High Power Sub-Femtosecond X-Ray Pulse Study for the LCLS

electron, simulation, space-charge, photon

2848

J.P. MacArthur
Stanford University, Stanford, California, USA
J.P. Duris, Z. Huang, A. Marinelli
SLAC, Menlo Park, California, USA

The desire to resolve sub-femtosecond electron dynamics has pushed FEL facilities to shorter pulse lengths. However, current short-pulse schemes provide low pulse energy and a gain-length limited lower bound on the pulse duration. The X-ray Laser-Enhanced Attosecond Pulses (XLEAP) project at SLAC is designed implement an Enhanced Self Amplified Spontaneous Emission (ESASE) scheme, which produces sub-fs current spikes by modulating and compressing the electron beam. We show through a series of Genesis simulations that the current spike is capable of producing sub-fs pulses with a peak power well above 100 GW. Space-charge induced beam chirp can decrease pulse lengths below 400 as, and multi-stage schemes can increase peak x-ray powers to around 1 TW.

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WEPIK053

Studies of Delta-Type Undulators for Sirius

polarization, storage-ring, lattice, dynamic-aperture

3045

L.N.P. Vilela, L. Liu, X.R. Resende, F.H. de Sá
LNLS, Campinas, Brazil

In this work we present the studies of the effects of Delta-type undulators in the storage ring beam dynamics of Sirius. The undulators were included in the ring model as kick maps and their effects on tune shift, dynamic aperture and beam lifetime were evaluated.

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WEPIK058

Preliminary Longitudinal Impedance Model for the ESRF-EBS

impedance, vacuum, simulation, storage-ring

3063

S.M. White
ESRF, Grenoble, France

In light sources, longitudinal beam coupling impedance can deteriorate performance through bunch lengthening or increased longitudinal emittance due to the microwave instability. Simulation estimates are therefore required to devise the appropriate counter-measures if necessary. The main contributors to the longitudinal impedance model of the new ESRF-EBS storage ring were simulated. A preliminary longitudinal impedance model is presented and preliminary tracking simulations are shown.

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WEPIK062

UNDUMAG - A New Computer Code to Calculate the Magnetic Properties of Undulators

synchrotron, damping, synchrotron-radiation, radiation

3071

M. Scheer
HZB, Berlin, Germany

A new code for the magnetic design of undulators is under development at the Helmholtz-Zentrum Berlin (BESSY). The program reads in the geometry and material properties of the undulator magnets and iron poles. Magnetic fields, forces and torques, as well as trajectories and synchrotron radiation can be calculated. The code is a stand-alone FORTRAN program, thus, only a FORTRAN compiler is needed to install it. Build-in graphic routines allows to write postscript files to visualize the geometry and the fields. Other results like 3D field maps, field integrals etc. are written to ASCII files for later use. The code will be published under the GNU general public license. First results and comparison to other codes are presented.

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WEPIK073

Three Dimensional Wake Field for an Electron Moving in Undulator

electron, radiation, electromagnetic-fields, wakefield

3098

K. Ohmi
KEK, Ibaraki, Japan

Electro-magnetic field for given trajectory of an electron is calculated by Lienard-Wiechert potential. The field near the electron moving in an undulator is presented. The field is regarded as a wake field in the undulator. Motion of a bunch is studied in the wake field.

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WEPIK080

Preliminary Study of Beam Dynamics Compensation for the Elliptically Polarized Undulator at the HLS-II

electron, simulation, software, dynamic-aperture

3114

Z.H. Yang, Z.H. Bai, W. Li, L. Wang
USTC/NSRL, Hefei, Anhui, People's Republic of China

An elliptically polarized undulator (EPU) was installed at the upgraded Hefei Light Source, HLS-II, for special users. Due to that the area of good field of the EPU is not large enough, the resulting beam dynamics is serious. At present, the lattice is changed to lower beta functions at the EPU to solve this problem. However, the compensation for the EPU is necessary for better operation of the machine in the future. In this paper, we used the surface fitting method to extract the Hamiltonian of the EPU from the real surface magnetic field data. Thus, we can obtain the effective Hamiltonian of the ring, which can be analyzed using normal form or other techniques. Then the beam dynamics effects resulting from the EPU can be compensated by optimizing the nonlinear quantities with striplines.

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WEPIK100

The Applicability of NEG Coated Undulator Vessels for the CLARA FEL Test Facility

vacuum, FEL, wakefield, impedance

3181

O.B. Malyshev, K.B. Marinov, K.J. Middleman, N. Thompson, R. Valizadeh, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
O.B. Malyshev, K.J. Middleman, N. Thompson, R. Valizadeh, P.H. Williams
Cockcroft Institute, Warrington, Cheshire, United Kingdom

CLARA is a FEL test facility at Daresbury Laboratory (DL), UK. The undulator vacuum chamber is 20 m long with inner diameter 6 mm and its vacuum performance can benefit from a NEG coating. The thickness of the coating layer must be carefully optimised. A layer ~ 1 um would help the vacuum but a thinner layer would be partially transparent for the EM field reducing the resistive wall wakefields due to the NEG. A very thin layer, however, may not yield the necessary vacuum performance. Two types of NEG coatings produced at DL - dense and columnar - were considered. Their bulk conductivities were measured in a separate study. The resistive wall wakefield impedance was calculated following the standard approach for multilayer vessels. A 250 fs rms electron bunch was generated in ASTRA and its wakefield was obtained from the vessel impedance. The FEL performance was then studied through GENESIS simulations and the result compared to the case with no wakefields. It was found that NEG layers thicker than 100 nm give an unacceptable reduction of the FEL power and the vacuum performance of such thin coatings is unknown. Possible solutions to this problem are discussed.

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WEPIK110

Resistive Wall Instability and Impedance Studies of Narrow Undulator Chamber in CHESS-U

lattice, simulation, wakefield, dipole

3204

S. Wang, M.G. Billing, S. Poprocki, D. L. Rubin, D. Sagan
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: Work supported by NSF DMR-0936384 and NSF DMR-1332208
In a major upgrade of the Cornell Electron Storage Ring (CESR) one sextant of ring will be replaced with double bend achromats (DBAs) and undulator straights for x-ray users. The resistive wall impedance from the narrow gap (4.5 mm) undulator chambers (5 m per straight) may limit total beam. Here we report recent results of modelling and calculation of multibunch instabilities due to the impedance of chamber walls and transition tapers. The short range wakefields and resistive wall impedance are modelled and incorporated in a tracking simulation. The coupled-bunch growth rate found with the tracking study is in good agreement with the analytic approximation. We find that the resistive wall instability can be readily damped by our existing bunch-by-bunch feedback system.

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WEPIK121

Computation of Synchrotron Radiation on Arbitrary Geometries in 3D with Modern GPU, Multi-Core, and Grid Computing

GPU, simulation, radiation, brightness

3238

D.A. Hidas
BNL, Upton, Long Island, New York, USA

Funding: Supported by the U.S. Department of Energy under contract DE-SC0012704
Open Source Code for Advanced Radiation Simulation (OSCARS*) is an open source project being developed at Brookhaven National Laboratory for the computation of synchrotron radiation from arbitrary particle beams in arbitrary magnetic (and electric) fields on arbitrary geometries in 3D. OSCARS was designed with considerations for modern large scale computing infrastructure. These include the ability to use GPUs for computations, multi-threaded computations, and utilities for grid (or cloud) computing. Primary applications include, but are not limited to, the computation of spectra, photon flux densities, and notably, power density distributions on arbitrary geometries in 3D which is of interest in accelerator component study and design. This modern approach and several complex geometries will be highlighted and elaborated on.
* http://oscars.bnl.gov

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WEPVA120

Beam Dynamics Simulation for EPU200 in TPS

emittance, electron, storage-ring, simulation

3551

M.-S. Chiu, C.H. Chen, J.Y. Chen, P.J. Chou, T.Y. Chung, Y.-C. Liu, F.H. Tseng
NSRRC, Hsinchu, Taiwan

The Taiwan Photon Source (TPS) is a low-emittance 3-GeV light source at Natioal Synchrotron Radiation Research Center (NSRRC). Five in-vacuum undulator beamlines were delivered to users on Sep. 22, 2016. To generate 10 ~ 500 eV photon with variuos polarizations, users proposed a new EPU : EPU200. In this paper, we present the preliminary results of beam dynamics simulation for EPU200.

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WEPVA148

Dynamics of Target Motion Under Exposure of Hard Gamma Undulator Radiation

target, positron, electron, photon

3618

A.A. Mikhailichenko
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

We describe time dependent dynamics of the target motion under exposure by undulator radiation in a system for positron production. We took into account inertia of material of target. Calculations carried with help of FlexPDE code.

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THPAB002

Update of the Collective Effects Studies for Sirius

impedance, simulation, radiation, operation

3680

F.H. de Sá, H.O.C. Duarte, L. Liu
LNLS, Campinas, Brazil

An updated impedance budget for Sirius, with contributions from 3D electromagnetic simulations and analytic calculations, is presented and the estimates for single and multi-bunch instability thresholds for the first operation phase are re-evaluated.

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THPAB053

Laser Heater Deisgn for the CLARA FEL Test Facility

laser, electron, FEL, dipole

3833

A.D. Brynes, S.P. Jamison, B.D. Muratori, N. Thompson, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
S.P. Jamison, B.D. Muratori, N. Thompson, P.H. Williams
Cockcroft Institute, Warrington, Cheshire, United Kingdom

We present considerations of microbunching studies in the CLARA (Compact Linear Accelerator for Research and Applications), the proposed UK FEL test facility under construction at Daresbury Laboratory. CLARA, a high-brightness electron linac, presents an opportunity to study the microbunching instability. A number of theoretical models have been proposed concerning the causes of this instability, and it has also been observed at various FEL facilities. We have applied these models to the CLARA FEL, and propose a suitable laser heater design which will provide flexibility in terms of the range of modes of operation for CLARA. We also propose a method for inducing and controlling the microbunching instability via pulse stacking of the photoinjector laser.

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THPAB078

Beam Dynamics Studies of the Transverse Gradient Undulator and Its Application to Suppression of Microbunching Instability

FEL, electron, focusing, laser

3895

T. Liu, Y. Ding, Z. Huang, W. Qin
SLAC, Menlo Park, California, USA
T. Liu
University of Chinese Academy of Sciences, Beijing, People's Republic of China
T. Liu, D. Wang
SINAP, Shanghai, People's Republic of China

A transverse gradient undulator (TGU) which was initially proposed for high gain free electron lasers (FELs) driven by electron beams with relatively large energy spread, can be extended to the application of beam dynamics, such as phase-merging enhanced harmonic generation FEL and suppression of microbunching instability. In this contribution we present beam dynamics studies of the TGU, analyze the resulting focusing and dispersion, and discuss the effects of an additional corrector on the TGU. As an application to beam dynamics, we show a feasible transport system based on the TGU as a reversible electron beam heater to suppress the microbunching instability of the electron beam.

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THPAB128

Beam Arrival Time Analisis Based on CBPM at DCLS

simulation, cavity, experiment, FEL

4023

S.S. Cao, J. Chen, L.W. Lai, Y.B. Leng
SINAP, Shanghai, People's Republic of China
N. Zhang
SSRF, Shanghai, People's Republic of China

Dalian Coherent Light Source is the first high gain free electron lasers (FEL) user facility in China, which is dedicated at extreme ultraviolet (EUV) spectral regime of 150-50nm for various scientific fields. In its undulator section, the beam-line was equipped with ten pair of high-precision cavity beam position monitor (CBPM), which can be used for beam position and beam arrival time (BAT) measurement. Based on this, we have done some preliminary research about the beam fight time with the reference cavities of CBPMs for the future research on BAT. In this paper, we presented the scheme of the beam fight time (BFT) research, analyzed the results, and evaluated the consistency and stability of BFT.

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THPIK080

Magnetic Performance of the New ALBA Magnetic Measurements Bench for Closed Structures

cyclotron, dipole, simulation, controls

4269

J. Campmany, L.G.O. Garcia-Orta, J. Marcos, V. Massana
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain

ALBA has designed and built a new magnetic measurement bench for closed structures, presented elsewhere. This bench has been fully built in-house and has been magnetically characterized at ALBA, showing excellent performance in terms of repeatability and accuracy. In the case of homogeneous fields, the accuracy reaches 10 microTesla, and in the case of undulators characterization, the accuracy of period determination reach 0.5 microns and the field accuracy is 60 microTesla. After this characterization, the bench has been moved to CIEMAT premises, and has been used to magnetically characterize the superconducting magnet of the AMIT cyclotron. In this paper we present the results of magnetic characterization of the bench as well as the first results of cyclotron measurements.

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THPVA060

Technical Overview of Inter-Undulator Support System for PAL XFEL

cavity, quadrupole, controls, feedback

4579

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

Pohang Accelerator Laboratory (PAL) has been developing a SASE X-ray Free Electron Laser based on 10 GeV linear accelerator. The inter-Undulator (IU) support system was developed to be used in the intersections of the Undulator Systems. The IU supports consist of phase shifter, quadrupole magnet with mover, beam loss monitor, cavity BPM with mover, two corrector magnets and vacuum components. The adjusting mechanism of IU Support has manual alignment system to be easily adjusting the component. The mover of quadruple magnet and cavity BPM with submicron repeatability has auto-adjusting systems with stepping motor. The mover main specifications include compact dimensions and a ±1.5 mm stroke in the vertical and horizontal direction. Linear motion guide based on 5-phase stepping motors have been chosen. This paper describes the design of the stages used for precise movement and results of mechanical measurements including reproducibility will be reported.

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THPVA067

Observation of Beam Disturbance Caused by ID Gap Variation at TLS Storage Ring

electron, injection, synchrotron, insertion-device

4598

H.C. Chen, C.L. Chen, H.H. Chen, C.H. Kuo, Y.K. Lin
NSRRC, Hsinchu, Taiwan

Insertion device is controlled by user for specific experimental condition on user beam time. It operates with user defined gap and phase. Three different undulators are installed in TLS (Taiwan Light Source), including one elliptically polarized undulator. Interactions between these undulators were studied to demonstrate the impact on beam performance. How to get more stable beam under undulators' interaction is discussed in this study.

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FRXBB1

Novosibirsk Four-Orbit ERL With Three FELs

FEL, electron, radiation, gun

4836

N.A. Vinokurov, V.S. Arbuzov, K.N. Chernov, I.V. Davidyuk, O.I. Deichuli, E.N. Dementyev, B.A. Dovzhenko, Ya.V. Getmanov, Ya.I. Gorbachev, B.A. Knyazev, E.I. Kolobanov, A.A. Kondakov, V.R. Kozak, E.V. Kozyrev, S.A. Krutikhin, V.V. Kubarev, G.N. Kulipanov, E.A. Kuper, I.V. Kuptsov, G.Y. Kurkin, L.E. Medvedev, S.V. Motygin, V.N. Osipov, V.K. Ovchar, V.M. Petrov, A.M. Pilan, V.M. Popik, V.V. Repkov, T.V. Salikova, M.A. Scheglov, I.K. Sedlyarov, S.S. Serednyakov, O.A. Shevchenko, A.N. Skrinsky, S.V. Tararyshkin, V.G. Tcheskidov, A.G. Tribendis, P. Vobly, V. Volkov
BINP SB RAS, Novosibirsk, Russia
I.V. Davidyuk, Ya.V. Getmanov, B.A. Knyazev, E.V. Kozyrev, S.S. Serednyakov, N.A. Vinokurov
NSU, Novosibirsk, Russia
A.G. Tribendis
NSTU, Novosibirsk, Russia

The Novosibirsk FEL facility has three FELs, installed on the first, second and fourth orbits of the ERL. The first FEL covers the wavelength range of 90 - 240 mkm at an average radiation power of up to 0.5 kW with a pulse repetition rate of 5.6 or 11.2 MHz and a peak power of up to 1 MW. The second FEL operates in the range of 40 - 80 mkm at an average radiation power of up to 0.5 kW with a pulse repetition rate of 7.5 MHz and a peak power of about 1 MW. These two FELs are the world's most powerful (in terms of average power) sources of coherent narrow-band (less than 1%) radiation in their wavelength ranges. The third FEL was commissioned in 2015 to cover the wavelength range of 5 - 20 mkm. The Novosibirsk ERL is the first and the only multiturn ERL in the world. Its peculiar features include the normal-conductive 180 MHz accelerating system, the DC electron gun with the grid thermionic cathode, three operation modes of the magnetic system, and a rather compact (6×40 m2) design. The facility has been operating for users of terahertz radiation since 2004.

Slides FRXBB1 [51.485 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-FRXBB1

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