IPAC2021 - List of Keywords (undulator)

Paper	Title	Other Keywords	Page
MOPAB018	SASE Gain-Curve Measurements with MCP-Based Detectors at the European XFEL	FEL, detector, photon, radiation	96
	E. Syresin, O.I. Brovko, A.Yu. Grebentsov JINR, Dubna, Moscow Region, Russia W. Freund, J. Grünert, J. Liu, Th. Maltezopoulos, D. Mamchyk EuXFEL, Schenefeld, Germany M.V. Yurkov DESY, Hamburg, Germany
	Radiation detectors based on microchannel plates (MCP) are used for characterization of the Free-Electron Laser (FEL) radiation and measurements of the Self-amplified spontaneous emission (SASE) gain curve at the European XFEL. Photon pulse energies are measured by the MCPs with an anode and by a photodiode. There is one MCP-based detector unit installed in each of the three photon beamlines downstream of the SASE1, SASE2, and SASE3 undulators. MCP detectors operate in a wide dynamic range of pulse energies, from the level of spontaneous emission up to FEL saturation. Their wavelength operation range overlaps with the whole range of radiation wavelengths of SASE1 and SASE2 (from 0.05 nm to 0.4 nm), and SASE3 (from 0.4 nm to 5 nm). In this paper we present results of SASE gain-curve measurements by the MCP-based detectors.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB018
About •	paper received ※ 18 May 2021 paper accepted ※ 17 August 2021 issue date ※ 23 August 2021
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MOPAB040	Gain of Hard X-Ray Fel at 3 GeV and Required Parameters	FEL, electron, laser, focusing	178
	L.H. Yu BNL, Upton, New York, USA
	We develop a tool for the calculation to study the conditions for a hard x-ray FEL oscillator based on an electron beam in the medium energy range from 3 to 4.5 GeV. We show that the approach developed by K.J. Kim et al. for the small-signal low gain formula can be modified so that the gain can be derived without taking the "no focusing approximation" adopted in the approach so that a strong focusing can be applied. We also derive the formula to allow for the gain calculation of harmonic lasing. The gain in this formula can be cast in the form of a product of two factors with one of them only depends on the harmonic number, undulator period, and gap. Thus this factor can be used to show that it is favorable to use harmonic lasing to achieve hard x-ray FEL working in the medium energy range and in the small-signal low gain regime.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB040
About •	paper received ※ 09 May 2021 paper accepted ※ 26 May 2021 issue date ※ 10 August 2021
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MOPAB084	Acceptance Tests and Installation of the IVU and Front End for the XAIRA Beamline of ALBA	photon, vacuum, experiment, insertion	318
	J. Campmany, J. Marcos, V. Massana ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
	XAIRA is a new beamline being built at ALBA synchrotron for macromolecular crystallography (MX) devoted to the study of small bio crystals. It aims at providing a full beam with a size of 3x1 µm² FWHM (hxv) and flux of >3·10¹² ph/s (250 mA in Storage Ring) at 1 Å wavelength (12.4 keV) to tackle MX projects for which only tiny (<10 μm) or imperfect crystals are obtained. Besides, XAIRA aims at providing photons at low energies, down to 4 keV, to support MX experiments exploiting the anomalous signal of the metals naturally occurring in proteins (native phasing), which is enhanced in the case of small crystals and long wavelengths. To this end, an in-vacuum undulator has been built by a consortium between Kyma and Research Instruments companies. In this paper, we present the results of the Site Acceptance Tests made at ALBA using a new bench developed to measure closed structures, and also the steps done for its installation in the ALBA tunnel.
	Poster MOPAB084 [1.715 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB084
About •	paper received ※ 11 May 2021 paper accepted ※ 20 May 2021 issue date ※ 25 August 2021
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MOPAB090	Status of HEPS Insertion Devices Design	photon, radiation, wiggler, insertion	339
	X.Y. Li, Y. Jiao, H.H. Lu, S.K. Tian IHEP, Beijing, People’s Republic of China
	HEPS is a 4th generation light source with the energy of 6 GeV and ultralow emittance of 34 pm.rad. A total of 14 beamlines with 19 insertion devices has been planned in the first phase, including 6 cryogenic undulators, 5 in-vacuum undulators, and two special non-planar IDs. The schemes and parameters of all the IDs are planned to be determined in this year. We report on the status of the design of these IDs and their effects on beam dynamics.
	Poster MOPAB090 [0.633 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB090
About •	paper received ※ 13 May 2021 paper accepted ※ 01 July 2021 issue date ※ 10 August 2021
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MOPAB099	Intensity Fluctuations Reduction in the Double-Bunch FEL at LCLS	FEL, electron, laser, free-electron-laser	369
	G. Zhou, A. Halavanau, C. Pellegrini SLAC, Menlo Park, California, USA
	In this paper we explore the possibility of reducing the intensity fluctuations of a hard X-ray double-bunch free-electron laser (DBFEL) by using an ultra-short, high peak current electron bunch to generate the seed signal, as studied recently for soft X-ray single bunch self-seeding. The ultra-short, nearly single-spike, SASE pulse is amplified to saturation, where a four-crystal monochromator selects a narrow bandwidth seed for the second bunch. Start-to-end simulation results for 7 keV photon energy are presented here for a DBFEL already studied for LCLS using the HXR undulator. We show that using this enhanced DBFEL (EDBFEL) system; the seed signal intensity fluctuations can be reduced from 85% to about 30%, and the second bunch intensity fluctuation at saturation to about 15%.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB099
About •	paper received ※ 24 May 2021 paper accepted ※ 16 July 2021 issue date ※ 31 August 2021
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MOPAB109	A Lattice for PETRA IV Based on the Combination of Different Arc Cell Designs	lattice, sextupole, emittance, resonance	399
	J. Keil, I.V. Agapov, R. Brinkmann DESY, Hamburg, Germany
	The 6 GeV synchrotron light source PETRA III at DESY is in user operation since 2009. In 2016 investigations of upgrading PETRA III into a diffraction limited storage ring at 10 keV have been started. The ambitious goal is to achieve an emittance in the range of 10-30 pm*rad. For the conceptual design report (CDR) of PETRA IV a lattice based on hybrid multi-bend achromats (HMBA) has been chosen. It consists of eight arcs connected by eight long straight sections whereas each arc consists of eight HMBA cells. While this lattice variant has an advantage in terms of simplicity of magnet and girder design it is challenging in regards of multipole strengths and beam dynamic properties. However, only a part of all eight arcs will be used for undulator beamlines. This offers the possibility to choose a more relaxed optics design in the arcs without undulators while preserving the ultra-low emittance. In addition, the use of reverse bends in the undulator cells allows smaller beta functions at the undulators for an increased brilliance. The design and the beam dynamic properties of this combi lattice are discussed in this paper and compared to the lattice based on HMBA cells.
	Poster MOPAB109 [1.338 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB109
About •	paper received ※ 18 May 2021 paper accepted ※ 28 May 2021 issue date ※ 30 August 2021
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MOPAB121	Progress Towards Soft X-Ray Beam Position Monitor Development	detector, radiation, laser, synchrotron	438
	B. Podobedov, C. Eng, S. Hulbert, C. Mazzoli BNL, Upton, New York, USA D. Donetski, K. Kucharczyk, J. Liu, R. Lutchman Stony Brook University, Stony Brook, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. X-ray beam position monitors (BPMs) are instrumental for storage ring light sources, where they reliably provide positional measurements of high-power beams in hard X-ray beamlines. However, despite a growing need, coming especially from coherent soft X-ray beamlines, non-invasive soft X-ray BPMs have not been demonstrated yet. We are presently working on a funded R&D proposal to develop a non-invasive soft X-ray BPM with micron-scale resolution for high-power white beams. In our approach, multi-pixel GaAs detector arrays are placed into the beam halo and beam position is inferred from the pixel photocurrent levels. Presently, the first detector array prototypes have been manufactured and are being prepared for low-power beam tests. The mechanical design of a BPM test-stand, which will be installed in the 23-ID canted soft X-ray undulator beamline at NSLS-II, is well under way. In addition, we are developing new algorithms of beam position calculation which take full advantage of extended multi-pixel detector arrays. In this paper we will review our design choices and discuss recent progress.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB121
About •	paper received ※ 03 June 2021 paper accepted ※ 13 July 2021 issue date ※ 28 August 2021
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MOPAB122	Present Status of HiSOR	synchrotron, storage-ring, injection, radiation	442
	M. Katoh UVSOR, Okazaki, Japan K. Goto, M. Katoh, M. Shimada HSRC, Higashi-Hiroshima, Japan H. Miyauchi KEK, Ibaraki, Japan
	HiSOR is a compact synchrotron light source of 700MeV. The circumference is 22m. The ring has two straight sections for undulators, which provide high brilliance VUV radiation. Two 180 bending magnets have 2.7 T field strength, which provide broadband radiation in VUV and soft X-ray range. The injector is a 150 MeV microtron. The beam injection is made twice a day with a 5 hour interval. Although the accelerators are being operated stably, the large emittance of 400nm makes it difficult to compete with high brilliance light sources of new generations. The compactness of the configuration makes it difficult to introduce new technologies. We have started seeking possible upgrades.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB122
About •	paper received ※ 18 May 2021 paper accepted ※ 20 May 2021 issue date ※ 30 August 2021
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MOPAB126	BESSY III & MLS II - Status of the Development of the New Photon Science Facility in Berlin	radiation, lattice, photon, emittance	451
	P. Goslawski, M. Abo-Bakr, F. Andreas, M. Arlandoo, J. Bengtsson, V. Dürr, K. Holldack, J.-G. Hwang, A. Jankowiak, B.C. Kuske, J. Li, A.N. Matveenko, T. Mertens, A. Meseck, E.C.M. Rial, M. Ries, M.K. Sauerborn, A. Schälicke, M. Scheer, P. Schnizer, L. Shi, J. Viefhaus HZB, Berlin, Germany J. Lüning UPMC, Paris, France
	HZB operates and develops two synchrotron radiation sources at Berlin Adlershof. The larger one, BESSY II with an energy of 1.7 GeV and 240 m circumference is optimized for soft-X rays and in operation since 1999. The smaller one is the MLS (Metrology Light Source), owned by the Physikalische Technische Bundesanstalt (PTB) - Germany’s National Metrology Institute. It is designed to fulfill the special metrology needs of the PTB with an energy of 0.6 GeV and 48 m circumference, covering the spectral range from THz and IR to EUV/VUV. In 2020 a discussion process has been started to define the requirements for successors of BESSY II and MLS and to study the possibilities integrate them into a new photon science facility in Berlin Adlershof. Here, we give a status report and present a first envisaged parameter space to both machines (see also MOPAB262, MOPAB220, MOPAB048, MOPAB242).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB126
About •	paper received ※ 18 May 2021 paper accepted ※ 24 June 2021 issue date ※ 18 August 2021
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MOPAB164	Miniature, High Strength Transport Line Design for Laser Plasma Accelerator-Driven FELs	laser, quadrupole, electron, plasma	561
	S. Fatehi, A. Bernhard, A.-S. Müller, M.S. Ning KIT, Karlsruhe, Germany
	Funding: This work is supported by the BMBF project 05K19VKA PlasmaFEL (Federal Ministry of Education and Research). Laser-plasma acceleration is an outstanding candidate to drive the next-generation compact light sources and FELs. To compensate large chromatic effects using novel compact beam optic elements in the beam transport line is required. We aim at designing miniature, high strength, normal conducting and superconducting transport line magnets and optics for capturing and matching LPA-generated electron bunches to given applications. Our primary application case is a demonstration experiment for transverse gradient undulator (TGU) FELs, to be performed at the JETI laser facility, Jena, Germany. In this contribution, we present the current design of the beam transport line magnets and the beam optics calculations. Laser Plasma Accelerators, FELs, Magnets, Beam Dynamics, Superconductivity, transverse gradient undulator
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB164
About •	paper received ※ 19 May 2021 paper accepted ※ 25 May 2021 issue date ※ 20 August 2021
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TUPAB064	Specifications and Performance of a Chicane Magnet for the cERL IR-FEL	FEL, dipole, operation, operational-performance	1512
	N. Nakamura, K. Harada, N. Higashi, Y. Honda, R. Kato, C. Mitsuda, S. Nagahashi, T. Obina, H. Sakai, M. Shimada, H. Takaki, O.A. Tanaka KEK, Ibaraki, Japan Y. Lu Sokendai, Ibaraki, Japan
	Funding: Work supported by NEDO project "Development of advanced laser processing with intelligence based high-brightness and high-efficiency laser technologies (TACMI project)". The IR-FEL was constructed in the Compact ERL (cERL) at KEK from October 2019 to May 2020 for the purpose of developing high-power mid-infrared lasers for high-efficiency laser processing utilizing molecular vibrational absorption. The chicane magnet was newly installed between two IR-FEL undulators in the cERL in order to increase the FEL gain and pulse energy by converting the energy modulation to the density modulation in an electron bunch. It consists of three dipole magnets with laminated yokes made of 0.1-mm-thick permalloy sheets and the coil currents of the three magnets are independently controlled by three power supplies with the maximum current of 10 A. The maximum closed orbit bump made by the chicane magnetic field has the longitudinal dispersion(R56) of -6 mm. The coil-current ratio of the three dipole magnets was tuned after installation to make its orbit bumps closed and then the chicane magnet was used in the FEL operation. We present specifications and operational performance of the chicane magnet.
	Poster TUPAB064 [4.053 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB064
About •	paper received ※ 18 May 2021 paper accepted ※ 25 May 2021 issue date ※ 25 August 2021
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TUPAB066	Status of the Short-Pulse Source at DELTA	laser, electron, bunching, simulation	1518
	A. Held, B. Büsing, H. Kaiser, S. Khan, D. Krieg, A.R. Krishnan, C. Mai DELTA, Dortmund, Germany
	Funding: Work supported by BMBF (05K19PEB). At the synchrotron light source DELTA operated by the TU Dortmund University, the short-pulse source employs the seeding scheme coherent harmonic generation (CHG) and provides ultrashort pulses in the vacuum ultraviolet and terahertz regime. Here, the interaction of laser pulses with the stored electron bunches result in a modulation of the longitudinal electron density which gives rise to coherent emission at harmonics of the laser wavelength. Recently, investigations of the influence of the Gouy phase shift at the focal point of the laser pulses on the laser-electron interaction have been performed. For the planned upgrade towards the more sophisticated seeding scheme echo-enabled harmonic generation (EEHG) featuring a twofold laser-electron interaction, simulations of the ideal parameters of the laser beams have been carried out.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB066
About •	paper received ※ 19 May 2021 paper accepted ※ 22 July 2021 issue date ※ 28 August 2021
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TUPAB071	Beam Line Design and Instrumentation for THz@PITZ - the Proof-of-Principle Experiment on a THz SASE FEL at the PITZ Facility	FEL, radiation, electron, experiment	1528
	T. Weilbach, P. Boonpornprasert, G.Z. Georgiev, G. Koss, M. Krasilnikov, X. Li, A. Lueangaramwong, F. Mueller, A. Oppelt, S. Philipp, F. Stephan, L.V. Vu DESY Zeuthen, Zeuthen, Germany H. Shaker CLS, Saskatoon, Saskatchewan, Canada
	In order to allow THz pump-X-ray probe experiments at full bunch repetition rate for users at the European XFEL, the Photo Injector Test Facility at DESY in Zeuthen (PITZ) is building a prototype of an accelerator-based THz source. The goal is to generate THz SASE FEL radiation with a mJ energy level per bunch using an LCLS-I undulator driven by the electron beam from PITZ. Therefore, the existing PITZ beam line is extended into a tunnel annex downstream of the existing accelerator tunnel. The beam line extension in the PITZ tunnel consists of three quadrupole magnets, a bunch compressor, a collimation system and a beam dump. In the second tunnel a dipole magnet allows to serve two beam lines, one of them the THz@PITZ beam line. It consists of one LCLS-I undulator for the production of the THz radiation, a quadrupole triplet in front of it and a quadrupole doublet behind it. For the electron beam diagnostic six new screen stations are built, three of them also allow for the observation of the THz radiation for measurements. In addition six BPMs and a new BLM system for machine protection and FEL gain curve measurement will be installed. The progress of this work will be presented.
	Poster TUPAB071 [1.978 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB071
About •	paper received ※ 18 May 2021 paper accepted ※ 14 June 2021 issue date ※ 13 August 2021
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TUPAB073	The Design of EEHG Cascaded Harmonic Lasing for SXFEL User Facility	FEL, electron, laser, radiation	1536
	K.Q. Zhang, C. Feng SSRF, Shanghai, People’s Republic of China H.X. Deng, B. Liu, T. Liu SARI-CAS, Pudong, Shanghai, People’s Republic of China
	The preliminary design and simulation results of EEHG cascaded harmonic lasing for the SXFEL user facility have been presented in this paper. Using the basic seeded beamline of the SXFEL user facility, the designed parameters are optimized to obtain full coherent FEL output at the 90th harmonic of a 265 nm seed laser. According to the designed parameters and the layout of the SXFEL user facility, the detailed simulations are carried out, the results show that the seeded beamline of the SXFEL user facility can generate 2.93 nm full coherent radiation by the proposed method, which indicates that the method can extend the photon energy range of a seeded FEL and the method can be achieved at the SXFEL user facility.
	Poster TUPAB073 [0.955 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB073
About •	paper received ※ 11 May 2021 paper accepted ※ 10 June 2021 issue date ※ 27 August 2021
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TUPAB080	Design and Status of the Beam Switchyard of the Shanghai Soft X-Ray FEL User Facility	FEL, electron, kicker, linac	1559
	S. Chen, R. Wang SSRF, Shanghai, People’s Republic of China H.X. Deng, C. Feng, X. Fu, B. Liu SARI-CAS, Pudong, Shanghai, People’s Republic of China
	SXFEL-UF, a soft X-ray FEL user facility located in Shanghai, has been upgraded from the existing test facility. Electron energy increases from 840 MeV to 1.5 GeV and a SASE FEL line will be added besides the existing seeding FEL line. It has started commissioning since early this year. In order for simultaneous operation of the two FEL lines, a beam switchyard is built between the linac and the two FEL lines. In this paper, the physics design of the beam switchyard is described.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB080
About •	paper received ※ 19 May 2021 paper accepted ※ 11 June 2021 issue date ※ 20 August 2021
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TUPAB081	Design of the Beam Distribution System of SHINE	linac, electron, septum, kicker	1562
	S. Chen, M. Gu, R. Wang SSRF, Shanghai, People’s Republic of China H.X. Deng, X. Fu SARI-CAS, Pudong, Shanghai, People’s Republic of China
	In shanghai, a hard X-ray free electron laser project named SHINE is under design. It will be based on a superconducting linac running in CW mode. On the first stage, there will be three parallel undulator lines downstream the linac. For simultaneous operation of the three undulator lines, a beam distribution system based on fast kickers will be installed between linac and undulator lines. The physics design of this beam distribution system is described in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB081
About •	paper received ※ 19 May 2021 paper accepted ※ 14 June 2021 issue date ※ 22 August 2021
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TUPAB086	FLASH2020+ Plans for a New Coherent Source at DESY	FEL, laser, electron, experiment	1581
	E. Allaria, N. Baboi, K. Baev, M. Beye, G. Brenner, F. Christie, C. Gerth, I. Hartl, K. Honkavaara, B. Manschwetus, J. Mueller-Dieckmann, R. Pan, E. Plönjes-Palm, O. Rasmussen, J. Rönsch-Schulenburg, L. Schaper, E. Schneidmiller, S. Schreiber, K.I. Tiedtke, M. Tischer, S. Toleikis, R. Treusch, M. Vogt, L. Winkelmann, M.V. Yurkov, J. Zemella DESY, Hamburg, Germany
	With FLASH2020+, a major upgrade of the FLASH facility has started to meet the new requirements of the growing soft-x ray user community. The design of the FEL beamlines aims at photon properties suitable to the needs of future user experiments with high repetition rate XUV and soft X-ray radiation. By the end of the project, both existing FEL lines at FLASH will be equipped with fully tunable undulators capable of delivering photon pulses with variable polarization. The use of the external seeding at 1 MHz in burst mode is part of the design of the new FLASH1 beamline, while FLASH2 will exploit novel lasing concepts based on different undulator configurations. The new FLASH2020+ will rely on an electron beam energy of 1.35 GeV that will extend the accessible wavelength range to the oxygen K-edge with variable polarization. The facility will be completed with new laser sources for pump and probe experiment and new experimental stations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB086
About •	paper received ※ 19 May 2021 paper accepted ※ 27 May 2021 issue date ※ 23 August 2021
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TUPAB092	Demonstration FELs Using UC-XFEL Technologies at the SAMURAI Laboratory	FEL, cryogenics, electron, laser	1592
	N. Majernik, G. Andonian, O. Camacho, A. Fukasawa, G.E. Lawler, W.J. Lynn, B. Naranjo, J.B. Rosenzweig, Y. Sakai, O. Williams UCLA, Los Angeles, California, USA R. Robles SLAC, Menlo Park, California, USA
	Funding: DOE HEP Grant DE-SC0020409, National Science Foundation Grant No. PHY-1549132 The ultra-compact x-ray free-electron laser (UC-XFEL), described in [J. B. Rosenzweig, et al. 2020 New J. Phys. 22 093067], combines several cutting edge beam physics techniques and technologies to realize an x-ray free electron laser at a fraction of the cost and footprint of existing XFEL installations. These elements include cryogenic, normally conducting RF structures for both the gun and linac, IFEL bunch compression, and short-period undulators. In this work, several stepping-stone, demonstrator scenarios under discussion for the UCLA SAMURAI Laboratory are detailed and simulated, employing different subsets of these elements. The cost, footprint, and technology risk for these scenarios are considered in addition to the anticipated engineering and physics experience gained.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB092
About •	paper received ※ 19 May 2021 paper accepted ※ 11 August 2021 issue date ※ 02 September 2021
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TUPAB099	Construction of an Infrared FEL at the Compact ERL	FEL, laser, operation, electron	1608
	R. Kato, M. Adachi, S. Eguchi, K. Harada, N. Higashi, Y. Honda, T. Miyajima, S. Nagahashi, N. Nakamura, K.N. Nigorikawa, T. Nogami, T. Obina, H. Sagehashi, H. Sakai, M. Shimada, T. Shioya, M. Tadano, R. Takai, O.A. Tanaka, Y. Tanimoto, K. Tsuchiya, T. Uchiyama, A. Ueda, M. Yamamoto KEK, Ibaraki, Japan R. Hajima QST, Tokai, Japan N.P. Norvell SLAC, Menlo Park, California, USA F. Sakamoto Akita National College of Technology, Akita, Japan M. Shimada HSRC, Higashi-Hiroshima, Japan
	Funding: Work supported by NEDO project "Development of advanced laser processing with intelligence based high-brightness and high-efficiency laser technologies (TACMI project)". The compact Energy Recovery Linac (cERL) has been in operation at KEK since 2013 to demonstrate ERL performance and develop ERL technology. Recently KEK has launched an infrared FEL project with a competitive funding. The purpose of this project is to build a mid-infrared FEL at the cERL, and to use that FEL as a light source for construction of the processing database required for industrial lasers. The FEL system is composed of two 3-m undulators and a matching section between them, and generates light with a maximum pulse energy of 0.1 micro-J at the wavelength of 20 microns with an 81.25 MHz repetition rate. The FEL is also expected to become a proof-of-concept machine for ERL base FELs for future EUV lithography.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB099
About •	paper received ※ 20 May 2021 paper accepted ※ 14 June 2021 issue date ※ 29 August 2021
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TUPAB100	FEL Design Elements of SABINA: A Free Electron Laser For THz-MIR Polarized Radiation Emission	radiation, electron, FEL, simulation	1612
	F. Dipace, E. Chiadroni, M. Ferrario, A. Ghigo, L. Giannessi, A. Giribono, L. Sabbatini, C. Vaccarezza INFN/LNF, Frascati, Italy A. Doria, A. Petralia ENEA C.R. Frascati, Frascati (Roma), Italy S. Lupi Sapienza University of Rome, Roma, Italy S. Macis La Sapienza University of Rome, Rome, Italy V. Petrillo Universita’ degli Studi di Milano, Milano, Italy V. Petrillo INFN-Milano, Milano, Italy
	Funding: SABINA is a project co-funded by Regione Lazio within POR-FESR 2014-2020 program. SABINA, acronym of "Source of Advanced Beam Imaging for Novel Applications", will be a Self-Amplified Spontaneous Emission Free Electron Laser (SASE FEL) providing a wide spectral range (from THz to MIR) of intense, short and variable polarization pulses for investigation in physics, chemistry, biology, cultural heritage, and material science. In order to reach these goals high brightness electron beams within a 30-100 MeV energy range, produced at SPARC photo-injector, will be transported up to an APPLE-X undulator through a dogleg. Space charge effects and Coherent Synchrotron Radiation (CSR) effects must be held under control to preserve beam quality. Studies on beam transport along the undulator and of the properties of the radiation field have been performed with "Genesis 1.3" simulation code. A downstream THz optics photon delivery system has also been designed to transport radiation on the long path from the undulator exit up to user experimental area.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB100
About •	paper received ※ 19 May 2021 paper accepted ※ 11 June 2021 issue date ※ 02 September 2021
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TUPAB101	Monte Carlo Simulations and Neutron and Gamma Fluence Measurements to Investigate Stray Radiation in the European XFEL Undulator System	electron, radiation, simulation, neutron	1615
	O.E. Falowska-Pietrzak, A. Hedqvist, F. Hellberg Stockholm University, Stockholm, Sweden N. Bassler DCPT, Aarhus N, Denmark A. Leuschner, D. Nölle DESY, Hamburg, Germany F. Wolff-Fabris EuXFEL, Schenefeld, Germany
	The European X-ray Free Electron Laser (XFEL) is an user facility research centre generating extremely bright and ultra-short SASE x-ray pulses. The laser flashes are generated when electrons of GeV energies pass the undulator systems. Even if the dominating contribution of the radiation field in the undulator is from spontaneous undulator radiation, also electron losses can be observed, e.g. during beam steering or due to beam halo, not captured by the upstream collimation system. The interactions of those particles with the vacuum vessel wall result in the emission of stray radiation. The LB 6419 detector allows to measure both the neutron and the gamma component in the pulsed radiation fields nearby the undulators. Usually, the real-time measurements show the dominance of the gamma signals. However, in case of particle loss occurs, a neutron signal is observed. In addition, Monte Carlo (MC) simulations conducted using the Geant4 code indicate that neutrons are also present within the undulator’s magnets volume. In this work, we present the LB 6419 measurement data and compare these to our MC simulations, to characterize the radiation field nearby the undulator segment. KLETT, A., LEUSCHNER, A., TESCH, N., A dose meter for pulsed neutron fields, Radiat Meas 45 (2010) 1242-1244
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB101
About •	paper received ※ 19 May 2021 paper accepted ※ 02 June 2021 issue date ※ 18 August 2021
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TUPAB104	Redesign of the FLASH2 Post-SASE Undulator Beamline	electron, quadrupole, photon, MMI	1626
	F. Christie, J. Rönsch-Schulenburg, S. Schreiber, M. Vogt, J. Zemella DESY, Hamburg, Germany
	FLASH2 is one of the two SASE (Self-Amplified Spontaneous Emission) undulator beamlines lines comprising variable gap undulators to produce radiation in the XUV and soft X-ray regime at FLASH. Downstream of the SASE undulators the beamline is currently undergoing a major redesign. During shutdowns in summer 2020 and winter 2021 two PolariX TDSs (Polarizable X-band Transverse Deflecting Structure) were installed, as well as additional diagnostics, to monitor the longitudinal phase space density of the electron bunches. Additionally, an afterburner undulator will be integrated in the next shutdown to produce circularly polarized light with wavelengths down to 1.39 nm. In this paper, we will present the modifications that were and will be made to the electron beamline in the course of this redesign.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB104
About •	paper received ※ 19 May 2021 paper accepted ※ 21 July 2021 issue date ※ 23 August 2021
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TUPAB106	Simulation Calculations of Compact THz Facility at IUAC, New Delhi	radiation, simulation, electron, optics	1633
	J. Karmakar, S. Ghosh IUAC, New Delhi, India
	A compact THz radiation source based on the principle of pre-bunched Free Electron Laser is at the commissioning stage at Inter University Accelerator Centre (IUAC), New Delhi. The facility will generate low emittance train of electron micro-bunches (2, 4, 8 or 16 numbers) from a RF photo-cathode gun in the energy range of 4 to 8 MeV and inject into a compact undulator to generate coherent THz radiation in the frequency range of ~0.18 to 3.0 THz. To optimize the intensity at a given frequency, the beam bunching factor and the betatron oscillation amplitude in the non-wiggling plane of the electronμbunches inside the undulator has been maximized and minimized respectively. The paper presents the optimized beam optics simulation results for two frequencies viz 0.5 and 2 THz. The on-axis radiation spectral intensity computed by in-house developed code using the trajectory data of the beam optics simulation is also presented for the two frequencies.
	Poster TUPAB106 [1.208 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB106
About •	paper received ※ 18 May 2021 paper accepted ※ 31 August 2021 issue date ※ 12 August 2021
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TUPAB107	Accelerator and Light Source Research Program at Duke University	FEL, polarization, storage-ring, electron	1636
	Y.K. Wu FEL/Duke University, Durham, North Carolina, USA
	Funding: This work is supported in part by the US DOE grant no. DE-FG02-97ER41033. The accelerator and light source research program at Duke Free-Electron Laser Laboratory (DFELL), TUNL, is focused on the development of the storage ring based free-electron lasers (FELs) and a state-of-the-art Compton gamma-ray source, the High Intensity Gamma-ray Source (HIGS) driven by the storage ring FEL. With a maximum total flux of about 3·10¹⁰ gamma/s and a spectral flux of more than 1,000 gamma/s/eV around 10 MeV, the HIGS is the world’s highest-flux Compton gamma-ray source. Operated in the energy range from 1 to 100 MeV, the HIGS is a premier Compton gamma-ray facility in the world for a variety of nuclear physics research programs, both fundamental and applied. In this work, we will describe our recent light source development to enable the production of gamma rays in the higher energy range from 100 and 120 MeV. We will also provide a summary of our recent accelerator physics and FEL physics research activities.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB107
About •	paper received ※ 26 May 2021 paper accepted ※ 14 July 2021 issue date ※ 15 August 2021
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TUPAB109	Characterization of the X-Ray Angular Pointing Jitter in the LCLS Hard X-ray Undulator Line	FEL, electron, cavity, detector	1640
	R.A. Margraf, Z. Huang, J.P. MacArthur, G. Marcus, T. Sato, D. Zhu SLAC, Menlo Park, California, USA Z. Huang Stanford University, Stanford, California, USA
	Funding: This work was supported by the Department of Energy, Laboratory Directed Research and Development program at SLAC National Accelerator Laboratory, under contract DE-AC02-76SF00515. The angular pointing jitter of X-ray pulses produced by an X-ray Free-Electron Laser (XFEL) depends on both intrinsic properties of the SASE (Self-amplified spontaneous emission) process and jitters in beamline variables such as electron orbit. This jitter is of interest to the Cavity-Based XFEL (CBXFEL)* project at SLAC, which will lase seven undulators inside an X-ray cavity of four diamond Bragg mirrors. The CBXFEL cavity has a narrow angular bandwidth, thus large angular jitters cause X-rays to leak out of the cavity and degrade cavity efficiency. To understand contributors to angular pointing jitter, we studied the pointing jitter of the Linac Coherent Light Source (LCLS) Hard X-ray Undulator line (HXU). Monochromatic and pink X-rays were characterized at the X-ray Pump Probe (XPP) instrument. We found pulses with high monochromatized pulse energy and small electron beam orbit in the undulator have the lowest angular pointing jitter. We present here our measurement results, discuss why these factors correlate with pointing stability, and propose a strategy for CBXFEL to reduce angular pointing jitter and account for angular pointing jitter in cavity efficiency measurements. *Gabriel Marcus et al. "CBXFEL Physics Requirements Document for the Optical cavity Based X-Ray Free Electron Lasers Research and Development Project." SLAC-I-120-103-121-00. Apr 2020.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB109
About •	paper received ※ 19 May 2021 paper accepted ※ 14 June 2021 issue date ※ 14 August 2021
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TUPAB111	Layout of the Laser Heater for FLASH2020+	electron, laser, FEL, free-electron-laser	1647
	C. Gerth, E. Allaria, A. Choudhuri, L. Schaper, E. Schneidmiller, S. Schreiber, M. Tischer, P. Vagin, M. Vogt, L. Winkelmann, M.V. Yurkov, J. Zemella DESY, Hamburg, Germany
	The major upgrade FLASH2020+ of the FEL user facility FLASH includes an improved injector layout for the generation of the high-brightness electron beam as well as an externally seeded FEL beamline. Microbunching gain of initial modulations or shot-noise fluctuations degrade the electron beam quality, which is in particular harmful to the external seed process. To minimize the microbunching gain by a controlled increase of the uncorrelated energy spread, the installation of a laser heater is foreseen directly upstream of the first bunch compression chicane. In this paper, we present the layout of the laser heater section, which follows the original proposal published almost 20 years ago and differs in several aspects from the common layout implemented at many other FEL facilities. The considerations that have been made for the optimisation of the laser heater parameters are described in detail.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB111
About •	paper received ※ 19 May 2021 paper accepted ※ 07 July 2021 issue date ※ 01 September 2021
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TUPAB113	Highlights From the Conceptual Design Report of the Soft X-Ray Laser at MAX IV	FEL, electron, laser, linac	1651
	F. Curbis, J. Andersson, L. Isaksson, B.S. Kyle, F. Lindau, E. Mansten, H. Tarawneh, P.F. Tavares, S. Thorin, A.S. Vorozhtsov MAX IV Laboratory, Lund University, Lund, Sweden S. Bonetti Stockholm University, Stockholm, Sweden V.A. Goryashko, P.M. Salén Uppsala University, Uppsala, Sweden P. Johnsson, S.P. Pirani, M.A. Pop, W. Qin, S. Werin Lund University, Lund, Sweden M. Larsson Stockholm University, Department of Physics, Stockholm, Sweden A. Nilsson FYSIKUM, AlbaNova, Stockholm University, Stockholm, Sweden J.A. Sellberg KTH Physics, Stockholm, Sweden
	Funding: Knut and Alice Wallenberg Foundation The SXL (Soft X-ray Laser) project developed a conceptual design for a soft X-ray Free Electron Laser in the 1–5 nm wavelength range, driven by the existing MAX IV 3 GeV linac. In this contribution we will focus on the FEL operation modes developed for the first phase of the project based on two different linac modes. The design work was supported by the Knut and Alice Wallenberg foundation and by several Swedish universities and organizations (Stockholm, Uppsala, KTH Royal Institute of Technology, Stockholm-Uppsala FEL center, MAX IV laboratory and Lund University).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB113
About •	paper received ※ 19 May 2021 paper accepted ※ 17 June 2021 issue date ※ 19 August 2021
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TUPAB114	FEL Performance and Beam Quality Assessment of Undulator Line for the CompactLight Facility.	FEL, brilliance, photon, electron	1655
	H.M. Castañeda Cortés, D.J. Dunning, N. Thompson STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Funding: H2020 CompactLight has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No. 777431 The H₂020 CompactLight Project aims for the design of innovative, cost-effective, compact FEL facilities to generate higher peak brilliance radiation in the soft and hard X-ray. In this paper we assess via simulation studies the performance of a variably polarising APPLE-X afterburner positioned downstream of a helical Super Conducting Undulator (SCU). We discuss the optimum balance between the active SCU length and the afterburner length, considering the peak brilliance and pulse energy of the output. Our studies are complemented with analysis of the optical beam quality of the afterburner output to determine the design constraints of the photon beamline that delivers the FEL output to the experimental areas. * Mak, A., Salen, P., Goryashko, V., Clarke, J., http://uu.diva-portal.org/smash/record.jsf?pid=diva2\%3A1280300&dswid=3236 ** Lutman, A. et al. Nature Photonics 10, 468
	Poster TUPAB114 [1.210 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB114
About •	paper received ※ 11 May 2021 paper accepted ※ 10 June 2021 issue date ※ 27 August 2021
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TUPAB115	Status Report of the Superconducting Free-Electron Laser FLASH at DESY	experiment, FEL, electron, operation	1659
	J. Rönsch-Schulenburg, F. Christie, K. Honkavaara, M. Kuhlmann, S. Schreiber, R. Treusch, M. Vogt, J. Zemella DESY, Hamburg, Germany
	The free-electron laser in Hamburg (FLASH) is a high brilliance XUV and soft X-ray SASE FEL user-facility at DESY. FLASH’s superconducting linac can accelerate several thousand electron bunches per second in 10 Hz bursts of up to 800 µs length. The long bunch trains can be split in two parts and shared between two undulator beamlines. During 2020, FLASH supplied, in standard operation, up to 500 bunches at 10 Hz in two bunch trains with independent fill patterns and compression schemes. The FLASH2 undulator beamline comprises variable gap undulators that allow different novel lasing schemes. A third beamline accommodates the FLASHForward plasma wakefield acceleration experiment. We report on the FLASH operation in 2019 - 2021 and present a few highlights.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB115
About •	paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 19 August 2021
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TUPAB116	Toward THz Coherent Undulator Radiation Experiment with a Combination of Velocity Bunchings	radiation, electron, bunching, acceleration	1663
	Y. Sumitomo, K. Hayakawa, Y. Hayakawa, K. Nogami, T. Sakai, T. Tanaka LEBRA, Funabashi, Japan
	Funding: Japan Society for the Promotion of Science (JSPS), Grant-in-Aid for Scientific Research (KAKENHI), Grant Number JP19K12631. We have launched a research program to generate the THz coherent undulator radiations, following the proposal of the combination of velocity bunchings * at Nihon University. The combination of velocity bunchings is an efficient way of bunch compression allowing a range of energy choices, in other words, a range of quasi-monochromatic radiation wavelengths generated at the undulator. In addition to the existing wideband THz light sources (0.1 - 2 THz) by the coherent edge and transition radiations currently available at Nihon Univ., the development of a high peak-power and quasi-monochromatic coherent radiation should accelerate the activities including the material science related to the THz bandwidths. In this presentation, we illustrate the program and report the current status of the experiment. * Y. Sumitomo et al., J. Phys. Conf. Ser., vol. 1067, p. 032017, 2018.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB116
About •	paper received ※ 19 May 2021 paper accepted ※ 15 June 2021 issue date ※ 15 August 2021
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TUPAB119	Beam Loss Study for the Implementation of Dechirper at the European XFEL	FEL, radiation, simulation, electron	1670
	J.J. Guo University of Chinese Academy of Sciences, Beijing, People’s Republic of China W. Decking, M.W. Guetg, J.J. Guo, S. Liu, W. Qin, I. Zagorodnov DESY, Hamburg, Germany Q. Gu, J.J. Guo SINAP, Shanghai, People’s Republic of China Q. Gu Shanghai Advanced Research Institute, Pudong, Shanghai, People’s Republic of China
	The European XFEL is a free-electron laser facility based on superconducting linac with high repetition rate up to 4.5 MHz. Wakefield structure (also called dechirper module) is planned to be installed in front of the SASE beam line at the European FEL, which can be used as a kicker for two-color scheme or a dechirper to control the bandwidth of SASE radiation. When the beam pass through the dechirper module, strong longitudinal and transverse wakefields can be excited to introduce a correlated energy chirp and a kick along the bunch. However, due to the relatively small gap of dechirper, beam halo particles hitting the dechirper module can lead to energy deposition and generate additional radiation, which can cause serious damage to the downstream undulators. For this reason, simulations have been performed using BDSIM to define the maximum acceptable beam halo, and the results are presented in this paper.
	Poster TUPAB119 [1.489 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB119
About •	paper received ※ 16 May 2021 paper accepted ※ 15 June 2021 issue date ※ 12 August 2021
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TUPAB122	SASE3 Variable Polarization Project at the European XFEL	polarization, vacuum, FEL, electron	1678
	S.K. Karabekyan, S. Abeghyan, M. Bagha-Shanjani, S. Casalbuoni, U. Englisch, G. Geloni, J. Grünert, S. Hauf, C. Holz, D. La Civita, J. Laksman, D. Mamchyk, M.P. Planas, F. Preisskorn, S. Serkez, H. Sinn, A. Violante, G. Wellenreuther, M. Wuenschel, M. Yakopov, C. Youngman EuXFEL, Schenefeld, Germany A. Block, W. Decking, N. Golubeva, K. Knebel, T. Ladwig, D.L. Lenz, D. Lipka, R. Mattusch, N. Mildner, E. Negodin, D. Nölle, J. Prenting, F. Saretzki, M. Schlösser, F. Schmidt-Föhre, E. Schneidmiller, D. Thoden, T. Wamsat, S. Wendt, T. Wilksen, T. Wohlenberg, M.V. Yurkov DESY, Hamburg, Germany M. Brügger, M. Calvi, S. Danner, R. Ganter, L. Huber, A. Keller, M.S. Schmidt, T. Schmidt PSI, Villigen PSI, Switzerland D.E. Kim PAL, Pohang, Republic of Korea Y. Li IHEP, People’s Republic of China
	At the European XFEL, two undulator systems for hard and one for soft X-rays have been successfully put into operation. The SASE3 soft X-ray undulator system generates linearly polarized radiation in the horizontal plane. One of the requirements for extending the radiation characteristics is the ability to obtain different polarization modes. These include both right and left circular, elliptical polarization, or linear polarization at an arbitrary angle. For this purpose, a system consisting of four APPLE X helical undulators developed at the Paul Scherrer Institute (PSI) is used. This paper presents the design parameters of the SASE3 undulator system after modifying it with the helical afterburner. It also describes the methods and the design solutions different from those used at PSI. The status and schedule of the project are introduced.
	Poster TUPAB122 [0.553 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB122
About •	paper received ※ 19 May 2021 paper accepted ※ 31 May 2021 issue date ※ 27 August 2021
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TUPAB125	Studies of Particle Losses From the Beam in the EU-XFEL Following Scattering by a Slotted Foil	radiation, FEL, simulation, diagnostics	1681
	A.T. Potter, A. Wolski The University of Liverpool, Liverpool, United Kingdom W. Decking, S. Liu DESY, Hamburg, Germany F. Jackson STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	One technique for producing short radiation pulses in an FEL involves the use of a slotted foil in a bunch compressor. However, the scattering of particles from the foil can lead to increased particle losses and the generation of secondary particles. This is a particular concern for high rep-rate FELs, such as the European XFEL, where there are plans to implement the slotted-foil technique for short pulse generation. The study reported here aims to characterise the impact of a slotted foil in the European XFEL on the radiation dose in the front section of one of the undulators. Simulations were performed using BDSIM: this code tracks primary particles along the beamline, models the interaction between particles and accelerator components and tracks secondary particles produced by these interactions. The results indicate the amount of energy deposited in the front section of one of the FEL undulators, and provide a basis for optimisation of the collimation system to keep the energy deposition and radiation doses within acceptable limits.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB125
About •	paper received ※ 19 May 2021 paper accepted ※ 10 June 2021 issue date ※ 28 August 2021
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TUPAB129	Beam Based Alignment in a Compact THz-FEL Facility	quadrupole, FEL, alignment, linac	1692
	Q.S. Chen, T. Hu, K.F. Liu, B. Qin, Y.Q. Xiong HUST, Wuhan, People’s Republic of China
	In this paper, we presented the beam based alignment results in a compact THz-FEL facility. The alignment was divided into two sections, the transport line and the optical line. In the transport line, all the five quadrupoles upstream of the undulator were adjusted one by one to fit the electron beam from the traveling wave linac. In the optical line, a set of auxiliary coils were winded on the yokes of the quadrupole downstream of the double bend achromat (DBA) to produce a vertical steering force. Another combined steering magnet, together with the auxiliary coils, corrected the beam orbit in the optical line. With the dispersion free test, the displacement between the magnetic centers of the quads and the beam orbit was less than 0.1mm.
	Poster TUPAB129 [0.673 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB129
About •	paper received ※ 18 May 2021 paper accepted ※ 17 June 2021 issue date ※ 27 August 2021
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TUPAB217	Effect of Undulators on Transverse Resonant Island Orbits	operation, diagnostics, dipole, optics	1927
	E.C.M. Rial, J. Bahrdt, P. Goslawski, A. Meseck, M. Ries, M. Scheer HZB, Berlin, Germany
	For one week in October 2020, BESSY II offered a Two Orbit mode to users for the first time. In this Two Orbit mode, the existence of transverse resonant island buckets* are exploited to store a second beam in the storage ring as an ’island orbit’, away from the primary beam axis. This mode was offered with free range of motion of the 12 out of vacuum undulators installed at the BESSY II ring. Diagnostics of the island orbit were limited to a single camera monitoring bending magnet radiation from a single dipole. A significant motion of the island orbit was observed on this diagnostic and correlated with undulator motion. This observation is reported, and simulations presented to demonstrate how this motion could arise. Correction schemes are suggested and discussed. Two Orbit - a report on the first scheduled week of TRIBs user operation at BESSY II, M. Ries et al, these proceedings *Proc. IPAC 2016, Busan, S Korea, paper THPMR017, p. 3427
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB217
About •	paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 22 August 2021
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TUPAB267	Investigation of Beam Impedance and Heat Load in a High Temperature Superconducting Undulator	impedance, laser, simulation, site	2089
	D. Astapovych, H. De Gersem, E. Gjonaj TEMF, TU Darmstadt, Darmstadt, Germany T.A. Arndt, E. Bründermann, N. Glamann, A.W. Grau, B. Krasch, A.-S. Müller, R. Nast, D. Saez de Jauregui, A. Will KIT, Eggenstein-Leopoldshafen, Germany
	The use of high temperature superconducting (HTS) materials can enhance the performance of superconducting undulators (SCU), which can later be implemented in free electron laser facilities, synchrotron storage rings and light sources. In particular, the short period < 10 mm undulators with narrow magnetic gap < 4 mm are relevant. One of the promising approaches considers a 10 cm meander-structured HTS tapes stacked one above the other. Then, the HTS tape is wound on the SCU. The idea of this jointless undulator has been proposed by, and is being further developed at KIT. Since minimizing the different sources of heat load is a critical issue for all SCUs, a detailed analysis of the impedance and heat load is required to meet the cryogenic system design. The dominant heat source is anticipated to be the resistive surface loss, which is one of the subjects of this study. Considering the complexity of the HTS tape, the impedance model includes the geometrical structure of the HTS tapes as well as the anomalous skin effect. The results of the numerical investigation performed by the help of the CST PS solver will be presented and discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB267
About •	paper received ※ 18 May 2021 paper accepted ※ 26 July 2021 issue date ※ 12 August 2021
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TUPAB373	Design of a Delta-type Superconducting Undulator at the IHEP	polarization, photon, permanent-magnet, radiation	2391
	J.H. Wei IHEP CSNS, Guangdong Province, People’s Republic of China C.D. Deng DNSC, Dongguan, People’s Republic of China L. Gong, X.Y. Li, X.C. Yang IHEP, Beijing, People’s Republic of China Y. Li DESY, Hamburg, Germany
	Undulators play an important role in the 4th generation radiation light source. In order to satisfy different requirements of the experiments, various undulator structures have been proposed. The Delta-type undulator can provide circular polarized radiation. Conventional undulators are usually made of permanent magnets, but the application of the superconducting technology in the undulator is developing quickly. Compared to the permanent magnet undulators, superconducting undulators can provide higher photon flux with the same magnetic pole gap and period length, especially when the period length is longer than 20 mm. An R&D project is underway to produce a protype of a Delta-type superconducting undulator with 28 mm long period and 12 mm gap at the IHEP. The structure design and the simulation results of the magnetic field are presented in this paper.
	Poster TUPAB373 [1.752 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB373
About •	paper received ※ 19 May 2021 paper accepted ※ 18 June 2021 issue date ※ 15 August 2021
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WEXC05	First Results Operating a Long-Period EPU in Universal Mode at the Canadian Light Source	polarization, photon, focusing, injection	2566
	W.A. Wurtz, C.K. Baribeau, D. Bertwistle, M.J. Sigrist CLS, Saskatoon, Saskatchewan, Canada
	The Quantum Materials Spectroscopy Centre beamline at the Canadian Light Source (CLS) requires photons with energies as low as 15 eV with circular polarization at the end station. This energy range is accomplished on the 2.9 GeV CLS storage ring using an elliptically polarizing undulator (EPU) with a 180 mm period, which we call EPU180. In order to realize circular polarized photons at the end station with this low energy, we must overcome two technical issues. First, the beamline optics distort the polarization of the light, so we compensate by providing light with a flattened, tilted polarization ellipse at the source point - a mode of operation known as universal mode. Second, the device has a strong effect on the electron beam due to dynamic focusing and is capable of reducing the injection efficiency to zero. We overcome this non-linear dynamic focusing using current strips adhered to the vacuum chamber. In this report, we present the first results with operating EPU180 in universal mode and we recover the dynamic aperture using the current strips.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEXC05
About •	paper received ※ 13 May 2021 paper accepted ※ 05 July 2021 issue date ※ 11 August 2021
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WEPAB087	Observation of Undulator Radiation Generated by a Single Electron Circulating in a Storage Ring and Possible Applications	synchrotron, electron, radiation, photon	2790
	I. Lobach University of Chicago, Chicago, Illinois, USA A. Halavanau, Z. Huang SLAC, Menlo Park, California, USA K. Kim ANL, Lemont, Illinois, USA S. Nagaitsev, A.L. Romanov, G. Stancari, A. Valishev Fermilab, Batavia, Illinois, USA
	An experimental study into the undulator radiation, generated by a single electron was carried out at the Integrable Optics Test Accelerator (IOTA) storage ring at Fermilab. The individual photons were detected by a Single Photon Avalanche Diode (SPAD) at an average rate of 1 detection per 300 revolutions in the ring. The detection events were continuously recorded by a picosecond event timer for as long as 1 minute at a time. The collected data were used to test if there is any deviation from the classically predicted Poissonian photostatistics. It was motivated by the observation * of sub-Poissonian statistics in a similar experiment. The observation * could be an instrumentation effect related to low detection efficiency and long detector dead time. In our experiment, the detector (SPAD) has a much higher efficiency (65%) and a much lower dead time. In addition, we show that the collected data (recorded detection times) can be used to study the synchrotron motion of a single electron and infer some parameters of the ring. For example, by comparing the results of simulation and measurement for the synchrotron motion we were able to estimate the magnitude of the RF phase jitter. * Teng Chen and John M. J. Madey, Phys. Rev. Lett. 86, 5906, June 2001
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB087
About •	paper received ※ 17 May 2021 paper accepted ※ 24 June 2021 issue date ※ 16 August 2021
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WEPAB088	Transverse Beam Emittance Measurement by Undulator Radiation Power Noise	radiation, emittance, optics, synchrotron	2794
	I. Lobach University of Chicago, Chicago, Illinois, USA A. Halavanau, Z. Huang SLAC, Menlo Park, California, USA K. Kim ANL, Lemont, Illinois, USA V.A. Lebedev, S. Nagaitsev, A.L. Romanov, G. Stancari, A. Valishev Fermilab, Batavia, Illinois, USA
	Generally, turn-to-turn power fluctuations of incoherent spontaneous synchrotron radiation in a storage ring depend on the 6D phase-space distribution of the electron bunch. In some cases, if only one parameter of the distribution is unknown, this parameter can be determined from the measured magnitude of these power fluctuations. In this contribution, we report the results of our experiment at the Integrable Optics Test Accelerator (IOTA) storage ring, where we carried out an absolute measurement (no free parameters or calibration) of a small vertical emittance (5–15 nm rms) of a flat beam by this new method, under conditions, when the small vertical emittance is unresolvable by a conventional synchrotron light beam size monitor.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB088
About •	paper received ※ 17 May 2021 paper accepted ※ 24 June 2021 issue date ※ 12 August 2021
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WEPAB126	Pulsed Wire Magnetic Field Measurement System for Short-Period Long Undulators	FEL, laser, detector, electron	2903
	J.E. Baader, S. Casalbuoni EuXFEL, Schenefeld, Germany
	The pulsed wire method is an attractive option to measure the magnetic field in insertion devices, mainly for those with restricted access (e.g., small gaps, in-vacuum/cryogenic environments, etc.). Besides first and second field integrals, experiments have proved the feasibility of reconstructing the magnetic field profile. Undulators with a small gap and short period are - and are planned to be - used at diffraction-limited storage rings and free-electron lasers. This contribution outlines the pulsed wire system’s requirements to perform magnetic field reconstruction in such undulators. We examine the main expected limitations, particularly the dispersive, finite pulse-width, discretization error, and sag effects. Furthermore, we present the current status of developing the pulsed wire system at the European XFEL.
	Poster WEPAB126 [1.184 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB126
About •	paper received ※ 19 May 2021 paper accepted ※ 07 July 2021 issue date ※ 19 August 2021
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WEPAB127	Accurate Measurements of Undulator Particle Beam Entrance/Exit Angles Using Improved Hall Probes and Calibration Process	photon, insertion, insertion-device, closed-orbit	2907
	I. Vasserman, R.J. Dejus, Y. Piao, M.F. Qian, J.Z. Xu ANL, Lemont, Illinois, USA
	Funding: Work supported by U.S. Department of Energy, Office of Science, under contract number DE-AC02-06CH11357. The Advanced Photon Source Upgrade (APS-U) undulator requirements were changed from the first and second field integrals to the entrance and exit angles of the particle beam. This provides the user with the best radiation view angle by the storage ring closed orbit correction system. To satisfy such requirements we use improved Senis Hall probes and calibration process. In addition to the normal NMR calibration of the sensors, the calibration was further refined using stretch-coil integrals to make accurate measurements.
	Poster WEPAB127 [0.620 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB127
About •	paper received ※ 15 May 2021 paper accepted ※ 09 June 2021 issue date ※ 19 August 2021
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WEPAB128	Recent Experience with Magnet Sorting for APS-U Hybrid Undulators	quadrupole, photon, permanent-magnet, synchrotron	2910
	I. Vasserman, R.J. Dejus, Y. Piao, M.F. Qian, J.Z. Xu ANL, Lemont, Illinois, USA
	Funding: Work supported by U.S. Department of Energy, Office of Science, under contract number DE-AC02-06CH11357. The quality of permanent magnets plays a particularly important role in undulator performance. Many different types of magnet sorting to enhance undulator performance have been carried out at different facilities. Meanwhile, progress in improving magnet quality has been made by different vendors. At the Advanced Photon Source (APS) we have assembled, measured, and analyzed over 14 new undulators of the same mechanical design, some of them with sorted magnets and some unsorted. The performance differences appear to be insignificant in meeting the tight APS Upgrade (APS-U) undulator requirements.
	Poster WEPAB128 [0.395 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB128
About •	paper received ※ 16 May 2021 paper accepted ※ 09 June 2021 issue date ※ 10 August 2021
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WEPAB129	A New Method of Undulator Phase Tuning with Mechanical Shimming	MMI, radiation, operation, permanent-magnet	2912
	M.F. Qian, R.J. Dejus, Y. Piao, I. Vasserman, J.Z. Xu ANL, Lemont, Illinois, USA
	Funding: Work supported by U.S. Department of Energy, Office of Science, under contract number DEAC02-06CH11357. We developed a new method for tuning the undulator phase errors by shimming the undulator gap profile mechanically. First, the phase errors of a device are calculated based on the initial field measurement; then the desired field strength modulation along the device length is derived from the phase errors; and finally, the gap profile is mechanically shimmed to produce the desire field strength modulation. The method has been successfully applied to the tuning of many new and reused APS Upgrade (APS-U) hybrid permanent magnet undulators. The method is especially effective for tuning the legacy undulators with large phase errors. For instance, an old 33-mm-period undulator with a 23 degree initial rms phase error largely due to radiation damage has been tuned to better than 3 degrees.
	Poster WEPAB129 [0.500 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB129
About •	paper received ※ 19 May 2021 paper accepted ※ 24 June 2021 issue date ※ 13 August 2021
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WEPAB130	Experience with Algorithm-Guided Tuning of APS-U Undulators	radiation, MMI, electron, permanent-magnet	2915
	M.F. Qian, R.J. Dejus, Y. Piao, I. Vasserman, J.Z. Xu ANL, Lemont, Illinois, USA
	Funding: Work supported by U.S. Department of Energy, Office of Science, under contract number DE AC02-06CH11357. The Advanced Photon Source (APS) is undergoing a major upgrade to its storage ring. The APS Upgrade (APS-U) project plans to build over 40 new hybrid permanent magnet undulators (HPMUs) and rebuild over 20 existing HPMUs. To meet the APS-U undulator requirements, the quality of the undulator magnetic field needs to be fine-tuned to the specifications. The traditional methods that depend on the tuning specialist experience are not desirable for tuning large quantities of undulators. We developed algorithms that automate the tuning of permanent magnet undulators. For tuning of the undulator trajectory and phase, the algorithms optimize the tuning parameters with differential evolution-based global optimization. The algorithms have been successfully applied to over 18 APS HPMUs. The results and experiences of the tuning are reported in detail.
	Poster WEPAB130 [0.543 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB130
About •	paper received ※ 19 May 2021 paper accepted ※ 24 June 2021 issue date ※ 12 August 2021
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WEPAB131	Magnetic Tuning and Installation Modifications of U48 Undulator for the Delhi Light Source (DLS)	electron, controls, vacuum, focusing	2918
	M. Tischer, P. Neumann, A. Schöps, P. Vagin, T. Vielitz, T. Wohlenberg DESY, Hamburg, Germany M. Aggarwal, R.N. Dutt, S. Ghosh, J. Karmakar, S. Sahu IUAC, New Delhi, India J. Bahrdt, E.C.M. Rial HZB, Berlin, Germany
	A compact THz radiation facility based on the principle of a pre-bunched Free Electron Laser, called Delhi Light Source (DLS) is at the final stage of commissioning at IUAC, New Delhi, India. For generation of THz radiation in DLS, an undulator with period length of 48 mm (U48), built by HZB and refurbished at DESY will be used. The magnetic tuning and the field measurements have been done on the U48 along with the design and installation of correction coils at the entrance/exit of the U48. In addition, horizontal and vertical ambient field correction coils were integrated into the magnet girders. A quadrupole correction coil along the vacuum chamber in order to mitigate the defocusing effect of the U48 on the electron beam has been designed. The current through all coils has been adjusted as a function of the gap by the new control system designed for the U48. In addition, an extruded aluminium vacuum chamber was designed and fabricated and will be aligned with the the undulator soon.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB131
About •	paper received ※ 19 May 2021 paper accepted ※ 05 July 2021 issue date ※ 11 August 2021
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WEPAB132	Towards a Superconducting Undulator Afterburner for the European XFEL	FEL, photon, electron, vacuum	2921
	S. Casalbuoni, J.E. Baader, G. Geloni, V. Grattoni, D. La Civita, C. Lechner, B. Marchetti, S. Serkez, H. Sinn EuXFEL, Schenefeld, Germany W. Decking, L. Lilje, S. Liu, T. Wohlenberg, I. Zagorodnov DESY, Hamburg, Germany
	We propose to develop, characterize and operate a superconducting undulator (SCU) afterburner consisting of 5 undulator modules (1 module = 2 times SCU coil of 2 m length and 1 phase shifter) at the SASE2 hard X-ray beamline of European XFEL. This afterburner has the potential to produce an output of more than 10¹⁰ ph/pulse at photon energies above 30 keV. The project is divided into the production of a pre-series prototype module and a small-series production of 5 modules. Central goals of this R&D activity are: the demonstration of the functionality of SCUs at an X-ray FEL, the set up of the needed infrastructure to characterize and operate SCUs, the industrialization of such undulators, and the reduction of the price per module. In this contribution, the main parameters and specifications of the pre-series prototype module (S-PRESSO) are described.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB132
About •	paper received ※ 15 May 2021 paper accepted ※ 05 July 2021 issue date ※ 14 August 2021
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WEPAB133	First Numerical Wakefield Studies of New In-Vacuum Cryogenic and APPLE II Undulators for BESSY II	impedance, simulation, vacuum, factory	2925
	M. Huck, J. Bahrdt, A. Meseck HZB, Berlin, Germany A. Meseck KPH, Mainz, Germany
	While the new in-vacuum cryogenic undulator is in its last commissioning stages, a worldwide new in-vacuum APPLE II undulator is being designed and constructed for BESSY II storage ring. Besides the challenging mechanical design of these small-gap and short-period undulators, challenges arise due to interaction with the electron beam. Therefore, detailed studies of this interaction is required to minimize the adverse effects on beam dynamics and the device itself. For this purpose, the wakefield effects have been computed numerically for critical parts of these devices i.e. the RF-shields, flexible tapers and taper sections. A brief overview of simulation results and discussions are presented in this paper.
	Poster WEPAB133 [0.795 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB133
About •	paper received ※ 19 May 2021 paper accepted ※ 23 July 2021 issue date ※ 23 August 2021
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WEPAB134	Experimental Studies of the In-Vacuum-Cryogenic Undulator Effect on Beam Instabilities at BESSY II	vacuum, feedback, damping, impedance	2929
	M. Huck, J. Bahrdt, A. Meseck, G. Rehm, M. Ries, A. Schälicke HZB, Berlin, Germany
	A new in-vacuum cryogenic permanent magnet undulator (CPMU17) has been installed in summer 2018 in the BESSY II storage ring at HZB. Such a small gap in-vacuum undulator device increases the impedance of the storage ring and can contribute to the instabilities that adversely affect the beam quality and the device itself. To identify and explore the effects of CPMU17 on the instabilities at BESSY II, grow-damp and drive-damp experiments have been conducted using the installed bunch-by-bunch feedback system. In this paper, the first results of the mode and gap analysis of these studies with a brief overview of other impedance studies will be presented.
	Poster WEPAB134 [1.079 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB134
About •	paper received ※ 17 May 2021 paper accepted ※ 02 July 2021 issue date ※ 23 August 2021
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WEPAB135	Progress of the Development of a Superconducting Undulator as a THz Source for FELs	radiation, FEL, electron, experiment	2933
	J. Gethmann, S. Casalbuoni, N. Glamann, A.W. Grau, A.-S. Müller, D. Saez de Jauregui KIT, Karlsruhe, Germany D. Astapovych, H. De Gersem, E. Gjonaj TEMF, TU Darmstadt, Darmstadt, Germany S. Casalbuoni EuXFEL, Schenefeld, Germany
	Funding: This work is supported by the BMBF project 05K19VK2 SCUXFEL (Federal Ministry of Education and Research) and by the DFG-funded Doctoral School KSETA: Science and Technology. To produce radiation in the THz frequency range at X-ray Free Electron Lasers, undulators with large period length, high fields, and large gaps are required. These demands can be fulfilled by superconducting undulators. In this contribution, the actual requirements on the main parameters of such a superconducting undulator will be discussed and the progress of the design will be discussed. In addition, beam impedance and heat load results obtained analytically as well as by large-scale wakefield simulations will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB135
About •	paper received ※ 19 May 2021 paper accepted ※ 02 July 2021 issue date ※ 31 August 2021
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WEPAB251	Beam Dynamics Optimization of LCLS-II HE Linear Accelerator Design	emittance, electron, radiation, FEL	3224
	J. Qiang LBNL, Berkeley, California, USA T.O. Raubenheimer, M.D. Woodley SLAC, Menlo Park, California, USA
	The LCLS-II-HE as a high energy upgrade of the high repetition rate X-ray FEL under construction at SLAC will provide great opportunities for scientific discovery by generating coherent, high brightness hard X-ray radiation. In this paper, we report on beam dynamics optimization of the LCLS-II HE linear accelerator design with a 100pC and a 20pC charge beam to attain high quality electron beam for X-ray FEL radiation. We also present preliminary results of beam dynamics optimization of a 100pC beam from a low emittance superconducting injector.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB251
About •	paper received ※ 18 May 2021 paper accepted ※ 21 June 2021 issue date ※ 30 August 2021
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WEPAB257	Matching of a Space-Charge Dominated Beam into the Undulator of the THz SASE FEL at PITZ	electron, experiment, quadrupole, FEL	3244
	X. Li, Z. Aboulbanine, G.D. Adhikari, N. Aftab, Z.G. Amirkhanyan, P. Boonpornprasert, M.E. Castro Carballo, N. Chaisueb, G.Z. Georgiev, J. Good, M. Groß, C. Koschitzki, M. Krasilnikov, O. Lishilin, A. Lueangaramwong, D. Melkumyan, R. Niemczyk, A. Oppelt, H.J. Qian, G. Shu, F. Stephan, G. Vashchenko, T. Weilbach DESY Zeuthen, Zeuthen, Germany
	The Photo Injector Test facility at DESY in Zeuthen (PITZ) is developing a THz SASE FEL as a prototype high repetition rate accelerator-based source for the THz-pumped, X-ray-probed experiments at the European XFEL. For the generation of THz pulses of mJ-level energy from SASE, an electron beam with a high charge (up to 4 nC) and high peak current (~200 A) will be injected into an LCLS-I undulator, which is currently being installed at the end of the photo-injector. The narrow vacuum chamber (11x5 mm) between the magnetic poles and the strong vertical focusing from the undulator, as well as the lack of beam diagnostics, have made it a challenge to match the space-charge dominated beam into the undulator without beam loss during the following transport. In this paper, boundary conditions of a matched electron beam will be discussed and the simulation and experimental study on our matching strategy will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB257
About •	paper received ※ 08 May 2021 paper accepted ※ 02 July 2021 issue date ※ 13 August 2021
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WEPAB270	Characterization and Simulation of Optical Delay System for the Proof-of-Principle Experiment of Optical Stochastic Cooling at IOTA	radiation, experiment, simulation, kicker	3269
	A.J. Dick, P. Piot Northern Illinois University, DeKalb, Illinois, USA J.D. Jarvis Fermilab, Batavia, Illinois, USA P. Piot ANL, Lemont, Illinois, USA
	Funding: CBB NSF-PHY-1549132 DOE DE-SC0018656 DOE DE-AC02-07CH11359 The Optical Stochastic Cooling (OSC) experiment at Fermilab’s IOTA storage ring uses two undulators to cool the beam over many turns. The radiation emitted by electrons in the first undulator is delayed and imaged in the second undulator where it applies a corrective energy kick on the electrons. Imperfections in the manufacturing of the delay plates can lead to a source of error. This paper presents the experimental characterization of the absolute thickness of these delay plates using an interferometric technique. The measured "thickness maps" are implemented in the Synchrotron Radiation Workshop (SRW) program to assess their impact on the delayed radiation pulse.
	Poster WEPAB270 [2.578 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB270
About •	paper received ※ 16 May 2021 paper accepted ※ 05 July 2021 issue date ※ 22 August 2021
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WEPAB271	Numerical Modelling of the Optical Stochastic Cooling Experiment at IOTA	simulation, radiation, damping, emittance	3273
	A.J. Dick, P. Piot Northern Illinois University, DeKalb, Illinois, USA J.D. Jarvis Fermilab, Batavia, Illinois, USA P. Piot ANL, Lemont, Illinois, USA
	Funding: CBB NSF-PHY-1549132 DOE DE-SC0018656 DOE DE-AC02-07CH11359 A proof-of-principle optical-stochastic cooling (OSC) experiment is currently in its commissioning phase at the Fermilab’s IOTA ring. In support of this experiment, we recently implemented an OSC element in the ELEGANT tracking program. The model, based on a semi-analytic description of OSC [], supports the simulation of a large number of macroparticles (10⁴-10⁶) over many turns (10⁶). This paper showcases the simulation capabilities to investigate the beam dynamics in the presence of cooling (or self-interacting radiation field in general) and quantify the impact of various sources of error (e.g. transverse and phase jitter), guide data analysis. B. Andorf, V. A. Lebedev, J. Jarvis, and P. Piot Rev. Accel. Beams 21, 100702 (2018)
	Poster WEPAB271 [1.649 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB271
About •	paper received ※ 16 May 2021 paper accepted ※ 06 July 2021 issue date ※ 13 August 2021
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WEPAB334	Development of Diffusion Bonded Joints of AA6061 Aluminum Alloy to AISI 316LN Stainless Steel for Sirius Planar Undulators	vacuum, interface, MMI, operation	3459
	R.L. Parise, O.R. Bagnato, R. Defavari, M.W.A. Feitosa, F.R. Francisco, D.Y. Kakizaki, R.D. Ribeiro LNLS, Campinas, Brazil
	LNLS has been commissioning Sirius, a 4th-generation synchrotron light source. The commissioning of the beamlines has been mainly done by using planar undulator, which uses in-house built aluminum vacuum chambers with ultra-high vacuum tight bimetallic flanges. In order to manufacture these flanges, diffusion bonded joints of AA6061 aluminum alloy to AISI 316LN stainless steel were developed. Diffusion bonding was carried out at 400-500°C for 45-60 min, applying a load of 9.8MPa in a vacuum furnace. Also, the surface preparation for Al and SS was investigated. SEM observation revealed that an 1-3 µm reaction layer was formed at the AA6061/Ni-plated interface. The intermetallic compound Al3Ni was identified in the reaction layer. The obtained Al/SS joints showed mean ultimate strength of 84 MPa, with the fracture occurring in the Al/reaction layer interface. Bake-out cycles followed by leak tests were carried out to validate the process and approve their use on the planar undulator vacuum chambers. Two undulators with Al/SS flanges have been installed and are under operation in the storage ring.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB334
About •	paper received ※ 17 May 2021 paper accepted ※ 17 June 2021 issue date ※ 31 August 2021
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WEPAB335	Aluminum Vacuum Chamber for the Sirius DELTA 52 Undulator	vacuum, storage-ring, synchrotron, emittance	3463
	T.M. Rocha, O.R. Bagnato, R.O. Ferraz, H.G. Filho, P.P.S. Freitas, G.R. Gomes, P.H. Lima, R.F. Oliveira, B.M. Ramos, F. Rodrigues, R.M. Seraphim, D.R. Silva, M.B. Silva LNLS, Campinas, Brazil
	Sirius is a 3 GeV fourth generation synchrotron light source under commissioning by the Brazilian Synchrotron Light Laboratory (LNLS). Delta Undulators with magnet vertical aperture of 13.6 mm, and period of 52.5 mm will be used for the generation of soft X rays to photoemission spectroscopy and X ray absorption experiments. Extruded aluminum vacuum chambers having small vertical aperture of 7.6 mm and horizontal aperture of 13 mm is proposed. This paper details the design and manufacturing processes of a complete chamber. Challenges regarding the TIG welding for aluminum and NEG coating for small aperture chambers will also be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB335
About •	paper received ※ 18 May 2021 paper accepted ※ 19 July 2021 issue date ※ 20 August 2021
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WEPAB336	Aluminum Vacuum Chamber for the Sirius Commissioning Undulators	vacuum, cathode, MMI, storage-ring	3467
	B.M. Ramos, O.R. Bagnato, R.O. Ferraz, H.G. Filho, P.P.S. Freitas, G.R. Gomes, P.H. Lima, R.F. Oliveira, T.M. Rocha, F. Rodrigues, R.M. Seraphim, D.R. Silva, M.B. Silva LNLS, Campinas, Brazil
	Sirius is a 3 GeV fourth generation light source under commissioning by the Brazilian Synchrotron Light Laboratory (LNLS). Compact Linear Polarizing Undulators with magnet vertical aperture of 8 mm have been used for the commissioning of some beam lines. Extruded aluminum vacuum chambers having small vertical aperture of 6 mm and horizontal aperture of 40 mm, were built. This paper details the design and manufacturing processes of a complete chamber and its installation procedure at the storage ring. Challenges regarding the precision machining of the 0.5 mm wall thickness, TIG welding for aluminum, NEG coating for small apertures will also be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB336
About •	paper received ※ 18 May 2021 paper accepted ※ 25 August 2021 issue date ※ 20 August 2021
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THXB07	Coherent Radiation From Inverse Compton Scattering Sources by Means of Particle Trapping	electron, laser, radiation, FEL	3732
	A. Fallahi, L. Novotny ETH Zurich, Photonics Laboratory, Zurich, Switzerland N. Kuster ETH, Zurich, Switzerland
	Funding: This work is supported by the Swiss National Science Foundation (SNSF) under the Spark grant CRSK-2-190840. Inverse Compton scattering (ICS) sources are one of the promising compact tools to generate short wavelength radiation from electron beams based on the relativistic Doppler effect. Nonetheless, these sources suffer from a few shortcomings such as incoherent radiation and low-efficiency in radiation generation. This contribution presents a novel scheme based on the scattering of an optical beam from a trapped electron beam inside an optical cavity. Inverse-Compton scattering off both free and trapped electrons are simulated using a full-wave solution of first-principle equations based on FDTD/PIC in the co-moving frame of electron beams. It is shown that the strong space-charge effect in low-energies is the main obstacle in acquiring coherent gain through the ICS mechanism. Subsequently, it is shown that by trapping the electron beam to the high-intensity spots, the space-charge effect is compensated, and additionally, the ultrahigh charge density enables high FEL-gain at trapping spots, thereby augmenting the coherence of the output radiation and concurrently increasing the source efficiency by three orders of magnitude.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THXB07
About •	paper received ※ 28 May 2021 paper accepted ※ 01 July 2021 issue date ※ 24 August 2021
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THPAB035	Study of the Tolerances for Superconducting Undulators at the European XFEL	FEL, electron, simulation, photon	3819
	B. Marchetti, S. Casalbuoni, V. Grattoni, S. Serkez EuXFEL, Schenefeld, Germany
	European XFEL is investing in the development of superconducting undulators (SCUs) for future upgrade of its beamlines SCUs made of NbTi, working at 2K, with a period length of 15 mm and a vacuum gap of 5 mm allow covering a range between 54 keV and 100 keV for 17.5 GeV electron energy. The effect of mechanical errors in the distribution of K along the undulators is more relevant for working points at lower photon energy, which are obtained using a higher magnetic field in the undulator. In this article we investigate the effect of error distribution in the K-parameter for a working point at 50keV photon energy obtained injecting an electron beam with 16.5 GeV energy from the XFEL linear accelerator in a undulator line composed by SCUs with 1.58 T peak magnetic field.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB035
About •	paper received ※ 12 May 2021 paper accepted ※ 05 July 2021 issue date ※ 18 August 2021
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THPAB036	Superconducting Phase Shifter Design for the Afterburner at the European XFEL	electron, FEL, photon, operation	3823
	V. Grattoni, J.E. Baader, S. Casalbuoni EuXFEL, Schenefeld, Germany
	At the European XFEL, a superconducting afterburner is under design for the SASE2 hard X-ray beamline. It will consist of 5 undulator modules. One module corresponds to two superconducting undulator (SCU) coils of 2 m length plus one phase shifter. Such an afterburner will enable photon energies above 30 keV. Superconducting (SC) phase shifters will be installed in each undulator module to keep the correct phase delay between the electron beam and photon beam. In this contribution, we present the required SC phase shifter parameters to enable operation in the electron beam energy range 11.5-17.5 GeV. We also analyze different magnetic designs satisfying the calculated specifications.
	Poster THPAB036 [0.991 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB036
About •	paper received ※ 18 May 2021 paper accepted ※ 06 July 2021 issue date ※ 12 August 2021
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THPAB037	Insertion Devices Impact on Solaris Storage Ring Optics	insertion, insertion-device, power-supply, storage-ring	3827
	G.W. Kowalski, R. Panaś, A.I. Wawrzyniak NSRC SOLARIS, Kraków, Poland
	Solaris storage ring is currently operating with three insertion devices. The IDs installed are the APPLE II type elliptically polarised undulators (EPU). The UARPES beamline is operating with the long period length EPU of 120 mm (EPU120) which has a significant impact on the linear optics and tune shift. The linear optics compensation of the EPU120 impact is realised by local adjustment of SQFO quadrupole/sextupole focusing gradient and defocusing gradient in the flanking dipoles. Two additional EPUs with period lengths of 58 and 46.6 mm are recently installed for next beamlines PHELIX and DEMETER, respectively and are under commissioning now. To reduce the impact of all undulators movement the additional correction coils are installed and the correction feedforward tables has been determined experimentally. Additionally to keep the tune at the nominal values the tune feedback is planned to be implemented. Within this presentation the effect of all existing insertion devices on the linear optics based on measurements and simulations to be discussed. Moreover the nonlinear effects, especially the impact on dynamic aperture of Solaris storage ring will be investigated.
	Poster THPAB037 [2.522 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB037
About •	paper received ※ 18 May 2021 paper accepted ※ 14 July 2021 issue date ※ 30 August 2021
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THPAB040	A Phase Shifter for Inline Undulators at the Advanced Photon Source Upgrade Project	photon, electron, permanent-magnet, radiation	3830
	E.R. Moog, R.J. Dejus, A.T. Donnelly, Y. Piao, M.F. Qian, I. Vasserman, J.Z. Xu ANL, Lemont, Illinois, USA
	Funding: Work supported by U.S. Department of Energy, Office of Science, under contract number DE AC02-06CH11357. Several undulator lines for the Advanced Photon Source Upgrade (APS-U) will consist of two inline undulators. In order to keep the undulators operating with optimal phasing over the full range of gaps, a phase shifter will be included between the undulators. A design has been developed for a phase shifter that will serve for a variety of undulator period lengths and gap ranges. The permanent-magnet phase shifter will use SmCo magnets to reduce the risk of radiation-induced demagnetization. The available space between the undulators is tight, so magnetic shields are placed between the undulators, the phase shifter, and the corrector magnet that is also located in the inter-undulator space. While these shields guard against magnetic cross-talk between the devices as the undulator and phase shifter gaps change, they do have an effect on the end fields of the devices. These end-field effects are examined and relevant tolerances are set and presented.
	Poster THPAB040 [0.429 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB040
About •	paper received ※ 23 May 2021 paper accepted ※ 21 June 2021 issue date ※ 14 August 2021
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THPAB041	Design of Photon Masks for the ILC Positron Source	photon, positron, site, target	3834
	K.S. Alharbi, G.A. Moortgat-Pick, A. Ushakov University of Hamburg, Hamburg, Germany K.S. Alharbi, S. Riemann DESY Zeuthen, Zeuthen, Germany K.S. Alharbi, A.O. Alrashdi King Abdulaziz City for Science and Technology (KACST), The National Center for Accelerator Technology, Riyadh, Kingdom of Saudi Arabia G.A. Moortgat-Pick DESY, Hamburg, Germany P. Sievers CERN, Geneva, Switzerland
	A long superconducting helical undulator is planned as baseline to produce polarized positrons at the International Linear Collider (ILC). To protect the undulator walls from synchrotron radiation, masks must be inserted along the undulator line. The power distribution deposited at these masks is studied in order to design the photon masks.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB041
About •	paper received ※ 19 May 2021 paper accepted ※ 07 July 2021 issue date ※ 12 August 2021
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THPAB042	Bending Radius Limits of Different Coated REBCO Conductor Tapes - An Experimental Investigation with Regard to HTS Undulators	experiment, collider, wiggler, positron	3837
	S.C. Richter, A. Bernhard, A. Drechsler, A.-S. Müller, B. Ringsdorf, S.I. Schlachter KIT, Karlsruhe, Germany S.C. Richter, D. Schoerling CERN, Geneva, Switzerland
	Funding: This work has been sponsored by the Wolfgang Gentner Programme of the German Federal Ministry of Education and Research (grant no. 05E18CHA). Compact FELs require short-period, high-field undulators in combination with compact accelerator structures to produce coherent light up to X-rays. Likewise, for the production of low emittance positron beams for future lepton colliders, like CLIC or FCC-ee, high-field damping wigglers are required. Applying high-temperature superconductors in form of coated REBCO tape conductors allows reaching higher magnetic fields and larger operating margins as compared to low-temperature superconductors like Nb-Ti or Nb₃Sn. However, short undulator periods like 13 mm may require bending radii of the conductor smaller than 5 mm inducing significant bending strain on the superconducting layer and may harm its conducting properties. In this paper, we present our designed bending rig and experimental results for REBCO tape conductors from various manufacturers and with different properties. Investigated bending radii reach from 20 mm down to 1 mm and optionally include half of a helical twist. To represent magnet winding procedures, the samples were bent at room temperature and then cooled down to T = 77 K in the bent state to test for potential degradation of the superconducting properties.
	Poster THPAB042 [1.871 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB042
About •	paper received ※ 19 May 2021 paper accepted ※ 18 June 2021 issue date ※ 25 August 2021
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THPAB043	A Superconducting Undulator for CompactLight: Resistive Wall Wakefield Analysis	wakefield, impedance, electron, FEL	3841
	K.B. Marinov STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	The CompactLight project is an advanced X-ray FEL light source, with high-frequency, high-gradient linacs and compact undulators. Lower electron energies give higher energy efficiency and a smaller environmental footprint. The extremely short bunch lengths (few fs) and narrow undulator gaps (4 mm) drastically increase the impact of resistive wall wakefields on the lasing process. The longitudinal resistive wall wakefield impedance is calculated in the framework of the surface impedance approach, in accordance with anomalous skin effect (ASE) theory. The dependence of the electron energy loss factor and the correlated energy spread of the bunch on the residual resistivity ratio (RRR) for both copper and aluminum is much higher for long (100 fs) than for ultra-short (6 fs) bunches. This is due to a known property of the longitudinal wakefield impedance - the field acting on a single particle traversing a resistive vessel does not depend on the conductivity of the vessel. The wakefields generated by the ultra-short bunch are already close to that of a single-particle regime and this leads to interesting consequences which are discussed in the present work.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB043
About •	paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 21 August 2021
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THPAB045	Design of a Short Period Helical Superconducting Undulator	FEL, electron, photon, simulation	3844
	A.G. Hinton STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom J. Boehm, L. Cooper, B. Green, T. Hayler, P. Jeffery, C.P. Macwaters STFC/RAL, Chilton, Didcot, Oxon, United Kingdom S. Milward DLS, Oxfordshire, United Kingdom B.J.A. Shepherd STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom B.J.A. Shepherd Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Superconducting technology provides the possibility to develop short period, small bore undulators that can generate much larger magnetic fields than alternative technologies. This may allow an XFEL with optimised superconducting undulators to cover a broader range of wavelengths than traditional undulators. At STFC, we have undertaken work to design and build a prototype helical superconducting undulator (HSCU) module with parameters suitable for use on a future XFEL facility. This work includes the design of a full 2 m long undulator module, including an undulator with 13 mm period and 5 mm inner winding diameter, the supporting cryogenic and vacuum systems required for operation, and quadrupoles, phase shifters and correction magnets for use between undulator sections. We present here the magnetic and mechanical design of the HSCU. The choice of undulator parameters and their influence on the design is discussed. A turnaround scheme to allow continuous winding of the undulator without the need for superconducting joints is also presented. Techniques for winding the undulator are currently being investigated and a short prototype will soon be wound and tested.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB045
About •	paper received ※ 17 May 2021 paper accepted ※ 18 June 2021 issue date ※ 21 August 2021
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THPAB047	Status of Magnetic Measurement Benches for Insertion Device Characterization at MAX IV Laboratory	insertion, insertion-device, quadrupole, MMI	3848
	M. Ebbeni, M. Gehlot, M. Holz, H. Tarawneh MAX IV Laboratory, Lund University, Lund, Sweden
	Insertion Devices (IDs) are the sole source of radiation used in all beamlines in MAX IV Laboratory with 14 IDs in operation of which 6 were built in-house. This paper shows the current capabilities and performance of the of the ID magnetic measurement systems, and the ongoing development work.
	Poster THPAB047 [1.185 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB047
About •	paper received ※ 11 May 2021 paper accepted ※ 27 July 2021 issue date ※ 28 August 2021
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THPAB048	Design and Fabrication Concepts of a Compact Undulator with Laser-Structured 2G-HTS Tapes	laser, simulation, FEL, impedance	3851
	A. Will, T.A. Arndt, E. Bründermann, N. Glamann, A.W. Grau, B. Krasch, A.-S. Müller, R. Nast, D. Saez de Jauregui KIT, Karlsruhe, Germany D. Astapovych, H. De Gersem, E. Gjonaj TEMF, TU Darmstadt, Darmstadt, Germany
	To produce small-scale high-field undulators for table-top free electron lasers (FELs), compact designs have been proposed using high temperature superconducting (HTS) tapes, which show both large critical current densities and high critical magnetic fields with a total tape thickness of about 50 μm and a width of up to 12 mm. Instead of winding coils, a meander structure can be laser-scribed directly into the superconductor layer, guiding the current path on a quasi-sinusoidal trajectory. Stacking pairs of such scribed tapes allows the generation of the desired sinusoidal magnetic fields above the tape plane, along the tape axis. Two practically feasible designs are presented, which are currently under construction at KIT: A coil concept wound from a single structured tape with a length of 15 m, which is a progression of a design that has been presented already in the past, as well as a novel stacked and soldered design, made from 25 cm long structured tapes, soldered in a zig-zag-pattern. In this contribution the designs are briefly recapped and the experimental progress is presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB048
About •	paper received ※ 19 May 2021 paper accepted ※ 12 July 2021 issue date ※ 15 August 2021

Paper

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Other Keywords

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MOPAB018

SASE Gain-Curve Measurements with MCP-Based Detectors at the European XFEL

FEL, detector, photon, radiation

96

E. Syresin, O.I. Brovko, A.Yu. Grebentsov
JINR, Dubna, Moscow Region, Russia
W. Freund, J. Grünert, J. Liu, Th. Maltezopoulos, D. Mamchyk
EuXFEL, Schenefeld, Germany
M.V. Yurkov
DESY, Hamburg, Germany

Radiation detectors based on microchannel plates (MCP) are used for characterization of the Free-Electron Laser (FEL) radiation and measurements of the Self-amplified spontaneous emission (SASE) gain curve at the European XFEL. Photon pulse energies are measured by the MCPs with an anode and by a photodiode. There is one MCP-based detector unit installed in each of the three photon beamlines downstream of the SASE1, SASE2, and SASE3 undulators. MCP detectors operate in a wide dynamic range of pulse energies, from the level of spontaneous emission up to FEL saturation. Their wavelength operation range overlaps with the whole range of radiation wavelengths of SASE1 and SASE2 (from 0.05 nm to 0.4 nm), and SASE3 (from 0.4 nm to 5 nm). In this paper we present results of SASE gain-curve measurements by the MCP-based detectors.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB018

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paper received ※ 18 May 2021 paper accepted ※ 17 August 2021 issue date ※ 23 August 2021

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MOPAB040

Gain of Hard X-Ray Fel at 3 GeV and Required Parameters

FEL, electron, laser, focusing

178

L.H. Yu
BNL, Upton, New York, USA

We develop a tool for the calculation to study the conditions for a hard x-ray FEL oscillator based on an electron beam in the medium energy range from 3 to 4.5 GeV. We show that the approach developed by K.J. Kim et al. for the small-signal low gain formula can be modified so that the gain can be derived without taking the "no focusing approximation" adopted in the approach so that a strong focusing can be applied. We also derive the formula to allow for the gain calculation of harmonic lasing. The gain in this formula can be cast in the form of a product of two factors with one of them only depends on the harmonic number, undulator period, and gap. Thus this factor can be used to show that it is favorable to use harmonic lasing to achieve hard x-ray FEL working in the medium energy range and in the small-signal low gain regime.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB040

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paper received ※ 09 May 2021 paper accepted ※ 26 May 2021 issue date ※ 10 August 2021

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MOPAB084

Acceptance Tests and Installation of the IVU and Front End for the XAIRA Beamline of ALBA

photon, vacuum, experiment, insertion

318

J. Campmany, J. Marcos, V. Massana
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain

XAIRA is a new beamline being built at ALBA synchrotron for macromolecular crystallography (MX) devoted to the study of small bio crystals. It aims at providing a full beam with a size of 3x1 µm² FWHM (hxv) and flux of >3·10¹² ph/s (250 mA in Storage Ring) at 1 Å wavelength (12.4 keV) to tackle MX projects for which only tiny (<10 μm) or imperfect crystals are obtained. Besides, XAIRA aims at providing photons at low energies, down to 4 keV, to support MX experiments exploiting the anomalous signal of the metals naturally occurring in proteins (native phasing), which is enhanced in the case of small crystals and long wavelengths. To this end, an in-vacuum undulator has been built by a consortium between Kyma and Research Instruments companies. In this paper, we present the results of the Site Acceptance Tests made at ALBA using a new bench developed to measure closed structures, and also the steps done for its installation in the ALBA tunnel.

Poster MOPAB084 [1.715 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB084

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paper received ※ 11 May 2021 paper accepted ※ 20 May 2021 issue date ※ 25 August 2021

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MOPAB090

Status of HEPS Insertion Devices Design

photon, radiation, wiggler, insertion

339

X.Y. Li, Y. Jiao, H.H. Lu, S.K. Tian
IHEP, Beijing, People’s Republic of China

HEPS is a 4th generation light source with the energy of 6 GeV and ultralow emittance of 34 pm.rad. A total of 14 beamlines with 19 insertion devices has been planned in the first phase, including 6 cryogenic undulators, 5 in-vacuum undulators, and two special non-planar IDs. The schemes and parameters of all the IDs are planned to be determined in this year. We report on the status of the design of these IDs and their effects on beam dynamics.

Poster MOPAB090 [0.633 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB090

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paper received ※ 13 May 2021 paper accepted ※ 01 July 2021 issue date ※ 10 August 2021

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MOPAB099

Intensity Fluctuations Reduction in the Double-Bunch FEL at LCLS

FEL, electron, laser, free-electron-laser

369

G. Zhou, A. Halavanau, C. Pellegrini
SLAC, Menlo Park, California, USA

In this paper we explore the possibility of reducing the intensity fluctuations of a hard X-ray double-bunch free-electron laser (DBFEL) by using an ultra-short, high peak current electron bunch to generate the seed signal, as studied recently for soft X-ray single bunch self-seeding. The ultra-short, nearly single-spike, SASE pulse is amplified to saturation, where a four-crystal monochromator selects a narrow bandwidth seed for the second bunch. Start-to-end simulation results for 7 keV photon energy are presented here for a DBFEL already studied for LCLS using the HXR undulator. We show that using this enhanced DBFEL (EDBFEL) system; the seed signal intensity fluctuations can be reduced from 85% to about 30%, and the second bunch intensity fluctuation at saturation to about 15%.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB099

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paper received ※ 24 May 2021 paper accepted ※ 16 July 2021 issue date ※ 31 August 2021

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MOPAB109

A Lattice for PETRA IV Based on the Combination of Different Arc Cell Designs

lattice, sextupole, emittance, resonance

399

J. Keil, I.V. Agapov, R. Brinkmann
DESY, Hamburg, Germany

The 6 GeV synchrotron light source PETRA III at DESY is in user operation since 2009. In 2016 investigations of upgrading PETRA III into a diffraction limited storage ring at 10 keV have been started. The ambitious goal is to achieve an emittance in the range of 10-30 pm*rad. For the conceptual design report (CDR) of PETRA IV a lattice based on hybrid multi-bend achromats (HMBA) has been chosen. It consists of eight arcs connected by eight long straight sections whereas each arc consists of eight HMBA cells. While this lattice variant has an advantage in terms of simplicity of magnet and girder design it is challenging in regards of multipole strengths and beam dynamic properties. However, only a part of all eight arcs will be used for undulator beamlines. This offers the possibility to choose a more relaxed optics design in the arcs without undulators while preserving the ultra-low emittance. In addition, the use of reverse bends in the undulator cells allows smaller beta functions at the undulators for an increased brilliance. The design and the beam dynamic properties of this combi lattice are discussed in this paper and compared to the lattice based on HMBA cells.

Poster MOPAB109 [1.338 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB109

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paper received ※ 18 May 2021 paper accepted ※ 28 May 2021 issue date ※ 30 August 2021

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MOPAB121

Progress Towards Soft X-Ray Beam Position Monitor Development

detector, radiation, laser, synchrotron

438

B. Podobedov, C. Eng, S. Hulbert, C. Mazzoli
BNL, Upton, New York, USA
D. Donetski, K. Kucharczyk, J. Liu, R. Lutchman
Stony Brook University, Stony Brook, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
X-ray beam position monitors (BPMs) are instrumental for storage ring light sources, where they reliably provide positional measurements of high-power beams in hard X-ray beamlines. However, despite a growing need, coming especially from coherent soft X-ray beamlines, non-invasive soft X-ray BPMs have not been demonstrated yet. We are presently working on a funded R&D proposal to develop a non-invasive soft X-ray BPM with micron-scale resolution for high-power white beams. In our approach, multi-pixel GaAs detector arrays are placed into the beam halo and beam position is inferred from the pixel photocurrent levels. Presently, the first detector array prototypes have been manufactured and are being prepared for low-power beam tests. The mechanical design of a BPM test-stand, which will be installed in the 23-ID canted soft X-ray undulator beamline at NSLS-II, is well under way. In addition, we are developing new algorithms of beam position calculation which take full advantage of extended multi-pixel detector arrays. In this paper we will review our design choices and discuss recent progress.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB121

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paper received ※ 03 June 2021 paper accepted ※ 13 July 2021 issue date ※ 28 August 2021

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MOPAB122

Present Status of HiSOR

synchrotron, storage-ring, injection, radiation

442

M. Katoh
UVSOR, Okazaki, Japan
K. Goto, M. Katoh, M. Shimada
HSRC, Higashi-Hiroshima, Japan
H. Miyauchi
KEK, Ibaraki, Japan

HiSOR is a compact synchrotron light source of 700MeV. The circumference is 22m. The ring has two straight sections for undulators, which provide high brilliance VUV radiation. Two 180 bending magnets have 2.7 T field strength, which provide broadband radiation in VUV and soft X-ray range. The injector is a 150 MeV microtron. The beam injection is made twice a day with a 5 hour interval. Although the accelerators are being operated stably, the large emittance of 400nm makes it difficult to compete with high brilliance light sources of new generations. The compactness of the configuration makes it difficult to introduce new technologies. We have started seeking possible upgrades.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB122

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paper received ※ 18 May 2021 paper accepted ※ 20 May 2021 issue date ※ 30 August 2021

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MOPAB126

BESSY III & MLS II - Status of the Development of the New Photon Science Facility in Berlin

radiation, lattice, photon, emittance

451

P. Goslawski, M. Abo-Bakr, F. Andreas, M. Arlandoo, J. Bengtsson, V. Dürr, K. Holldack, J.-G. Hwang, A. Jankowiak, B.C. Kuske, J. Li, A.N. Matveenko, T. Mertens, A. Meseck, E.C.M. Rial, M. Ries, M.K. Sauerborn, A. Schälicke, M. Scheer, P. Schnizer, L. Shi, J. Viefhaus
HZB, Berlin, Germany
J. Lüning
UPMC, Paris, France

HZB operates and develops two synchrotron radiation sources at Berlin Adlershof. The larger one, BESSY II with an energy of 1.7 GeV and 240 m circumference is optimized for soft-X rays and in operation since 1999. The smaller one is the MLS (Metrology Light Source), owned by the Physikalische Technische Bundesanstalt (PTB) - Germany’s National Metrology Institute. It is designed to fulfill the special metrology needs of the PTB with an energy of 0.6 GeV and 48 m circumference, covering the spectral range from THz and IR to EUV/VUV. In 2020 a discussion process has been started to define the requirements for successors of BESSY II and MLS and to study the possibilities integrate them into a new photon science facility in Berlin Adlershof. Here, we give a status report and present a first envisaged parameter space to both machines (see also MOPAB262, MOPAB220, MOPAB048, MOPAB242).

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB126

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paper received ※ 18 May 2021 paper accepted ※ 24 June 2021 issue date ※ 18 August 2021

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MOPAB164

Miniature, High Strength Transport Line Design for Laser Plasma Accelerator-Driven FELs

laser, quadrupole, electron, plasma

561

S. Fatehi, A. Bernhard, A.-S. Müller, M.S. Ning
KIT, Karlsruhe, Germany

Funding: This work is supported by the BMBF project 05K19VKA PlasmaFEL (Federal Ministry of Education and Research).
Laser-plasma acceleration is an outstanding candidate to drive the next-generation compact light sources and FELs. To compensate large chromatic effects using novel compact beam optic elements in the beam transport line is required. We aim at designing miniature, high strength, normal conducting and superconducting transport line magnets and optics for capturing and matching LPA-generated electron bunches to given applications. Our primary application case is a demonstration experiment for transverse gradient undulator (TGU) FELs, to be performed at the JETI laser facility, Jena, Germany. In this contribution, we present the current design of the beam transport line magnets and the beam optics calculations.
Laser Plasma Accelerators, FELs, Magnets, Beam Dynamics, Superconductivity, transverse gradient undulator

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB164

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paper received ※ 19 May 2021 paper accepted ※ 25 May 2021 issue date ※ 20 August 2021

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TUPAB064

Specifications and Performance of a Chicane Magnet for the cERL IR-FEL

FEL, dipole, operation, operational-performance

1512

N. Nakamura, K. Harada, N. Higashi, Y. Honda, R. Kato, C. Mitsuda, S. Nagahashi, T. Obina, H. Sakai, M. Shimada, H. Takaki, O.A. Tanaka
KEK, Ibaraki, Japan
Y. Lu
Sokendai, Ibaraki, Japan

Funding: Work supported by NEDO project "Development of advanced laser processing with intelligence based high-brightness and high-efficiency laser technologies (TACMI project)".
The IR-FEL was constructed in the Compact ERL (cERL) at KEK from October 2019 to May 2020 for the purpose of developing high-power mid-infrared lasers for high-efficiency laser processing utilizing molecular vibrational absorption. The chicane magnet was newly installed between two IR-FEL undulators in the cERL in order to increase the FEL gain and pulse energy by converting the energy modulation to the density modulation in an electron bunch. It consists of three dipole magnets with laminated yokes made of 0.1-mm-thick permalloy sheets and the coil currents of the three magnets are independently controlled by three power supplies with the maximum current of 10 A. The maximum closed orbit bump made by the chicane magnetic field has the longitudinal dispersion(R56) of -6 mm. The coil-current ratio of the three dipole magnets was tuned after installation to make its orbit bumps closed and then the chicane magnet was used in the FEL operation. We present specifications and operational performance of the chicane magnet.

Poster TUPAB064 [4.053 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB064

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paper received ※ 18 May 2021 paper accepted ※ 25 May 2021 issue date ※ 25 August 2021

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TUPAB066

Status of the Short-Pulse Source at DELTA

laser, electron, bunching, simulation

1518

A. Held, B. Büsing, H. Kaiser, S. Khan, D. Krieg, A.R. Krishnan, C. Mai
DELTA, Dortmund, Germany

Funding: Work supported by BMBF (05K19PEB).
At the synchrotron light source DELTA operated by the TU Dortmund University, the short-pulse source employs the seeding scheme coherent harmonic generation (CHG) and provides ultrashort pulses in the vacuum ultraviolet and terahertz regime. Here, the interaction of laser pulses with the stored electron bunches result in a modulation of the longitudinal electron density which gives rise to coherent emission at harmonics of the laser wavelength. Recently, investigations of the influence of the Gouy phase shift at the focal point of the laser pulses on the laser-electron interaction have been performed. For the planned upgrade towards the more sophisticated seeding scheme echo-enabled harmonic generation (EEHG) featuring a twofold laser-electron interaction, simulations of the ideal parameters of the laser beams have been carried out.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB066

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paper received ※ 19 May 2021 paper accepted ※ 22 July 2021 issue date ※ 28 August 2021

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TUPAB071

Beam Line Design and Instrumentation for THz@PITZ - the Proof-of-Principle Experiment on a THz SASE FEL at the PITZ Facility

FEL, radiation, electron, experiment

1528

T. Weilbach, P. Boonpornprasert, G.Z. Georgiev, G. Koss, M. Krasilnikov, X. Li, A. Lueangaramwong, F. Mueller, A. Oppelt, S. Philipp, F. Stephan, L.V. Vu
DESY Zeuthen, Zeuthen, Germany
H. Shaker
CLS, Saskatoon, Saskatchewan, Canada

In order to allow THz pump-X-ray probe experiments at full bunch repetition rate for users at the European XFEL, the Photo Injector Test Facility at DESY in Zeuthen (PITZ) is building a prototype of an accelerator-based THz source. The goal is to generate THz SASE FEL radiation with a mJ energy level per bunch using an LCLS-I undulator driven by the electron beam from PITZ. Therefore, the existing PITZ beam line is extended into a tunnel annex downstream of the existing accelerator tunnel. The beam line extension in the PITZ tunnel consists of three quadrupole magnets, a bunch compressor, a collimation system and a beam dump. In the second tunnel a dipole magnet allows to serve two beam lines, one of them the THz@PITZ beam line. It consists of one LCLS-I undulator for the production of the THz radiation, a quadrupole triplet in front of it and a quadrupole doublet behind it. For the electron beam diagnostic six new screen stations are built, three of them also allow for the observation of the THz radiation for measurements. In addition six BPMs and a new BLM system for machine protection and FEL gain curve measurement will be installed. The progress of this work will be presented.

Poster TUPAB071 [1.978 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB071

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paper received ※ 18 May 2021 paper accepted ※ 14 June 2021 issue date ※ 13 August 2021

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TUPAB073

The Design of EEHG Cascaded Harmonic Lasing for SXFEL User Facility

FEL, electron, laser, radiation

1536

K.Q. Zhang, C. Feng
SSRF, Shanghai, People’s Republic of China
H.X. Deng, B. Liu, T. Liu
SARI-CAS, Pudong, Shanghai, People’s Republic of China

The preliminary design and simulation results of EEHG cascaded harmonic lasing for the SXFEL user facility have been presented in this paper. Using the basic seeded beamline of the SXFEL user facility, the designed parameters are optimized to obtain full coherent FEL output at the 90th harmonic of a 265 nm seed laser. According to the designed parameters and the layout of the SXFEL user facility, the detailed simulations are carried out, the results show that the seeded beamline of the SXFEL user facility can generate 2.93 nm full coherent radiation by the proposed method, which indicates that the method can extend the photon energy range of a seeded FEL and the method can be achieved at the SXFEL user facility.

Poster TUPAB073 [0.955 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB073

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paper received ※ 11 May 2021 paper accepted ※ 10 June 2021 issue date ※ 27 August 2021

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TUPAB080

Design and Status of the Beam Switchyard of the Shanghai Soft X-Ray FEL User Facility

FEL, electron, kicker, linac

1559

S. Chen, R. Wang
SSRF, Shanghai, People’s Republic of China
H.X. Deng, C. Feng, X. Fu, B. Liu
SARI-CAS, Pudong, Shanghai, People’s Republic of China

SXFEL-UF, a soft X-ray FEL user facility located in Shanghai, has been upgraded from the existing test facility. Electron energy increases from 840 MeV to 1.5 GeV and a SASE FEL line will be added besides the existing seeding FEL line. It has started commissioning since early this year. In order for simultaneous operation of the two FEL lines, a beam switchyard is built between the linac and the two FEL lines. In this paper, the physics design of the beam switchyard is described.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB080

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paper received ※ 19 May 2021 paper accepted ※ 11 June 2021 issue date ※ 20 August 2021

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TUPAB081

Design of the Beam Distribution System of SHINE

linac, electron, septum, kicker

1562

S. Chen, M. Gu, R. Wang
SSRF, Shanghai, People’s Republic of China
H.X. Deng, X. Fu
SARI-CAS, Pudong, Shanghai, People’s Republic of China

In shanghai, a hard X-ray free electron laser project named SHINE is under design. It will be based on a superconducting linac running in CW mode. On the first stage, there will be three parallel undulator lines downstream the linac. For simultaneous operation of the three undulator lines, a beam distribution system based on fast kickers will be installed between linac and undulator lines. The physics design of this beam distribution system is described in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB081

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paper received ※ 19 May 2021 paper accepted ※ 14 June 2021 issue date ※ 22 August 2021

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TUPAB086

FLASH2020+ Plans for a New Coherent Source at DESY

FEL, laser, electron, experiment

1581

E. Allaria, N. Baboi, K. Baev, M. Beye, G. Brenner, F. Christie, C. Gerth, I. Hartl, K. Honkavaara, B. Manschwetus, J. Mueller-Dieckmann, R. Pan, E. Plönjes-Palm, O. Rasmussen, J. Rönsch-Schulenburg, L. Schaper, E. Schneidmiller, S. Schreiber, K.I. Tiedtke, M. Tischer, S. Toleikis, R. Treusch, M. Vogt, L. Winkelmann, M.V. Yurkov, J. Zemella
DESY, Hamburg, Germany

With FLASH2020+, a major upgrade of the FLASH facility has started to meet the new requirements of the growing soft-x ray user community. The design of the FEL beamlines aims at photon properties suitable to the needs of future user experiments with high repetition rate XUV and soft X-ray radiation. By the end of the project, both existing FEL lines at FLASH will be equipped with fully tunable undulators capable of delivering photon pulses with variable polarization. The use of the external seeding at 1 MHz in burst mode is part of the design of the new FLASH1 beamline, while FLASH2 will exploit novel lasing concepts based on different undulator configurations. The new FLASH2020+ will rely on an electron beam energy of 1.35 GeV that will extend the accessible wavelength range to the oxygen K-edge with variable polarization. The facility will be completed with new laser sources for pump and probe experiment and new experimental stations.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB086

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paper received ※ 19 May 2021 paper accepted ※ 27 May 2021 issue date ※ 23 August 2021

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TUPAB092

Demonstration FELs Using UC-XFEL Technologies at the SAMURAI Laboratory

FEL, cryogenics, electron, laser

1592

N. Majernik, G. Andonian, O. Camacho, A. Fukasawa, G.E. Lawler, W.J. Lynn, B. Naranjo, J.B. Rosenzweig, Y. Sakai, O. Williams
UCLA, Los Angeles, California, USA
R. Robles
SLAC, Menlo Park, California, USA

Funding: DOE HEP Grant DE-SC0020409, National Science Foundation Grant No. PHY-1549132
The ultra-compact x-ray free-electron laser (UC-XFEL), described in [J. B. Rosenzweig, et al. 2020 New J. Phys. 22 093067], combines several cutting edge beam physics techniques and technologies to realize an x-ray free electron laser at a fraction of the cost and footprint of existing XFEL installations. These elements include cryogenic, normally conducting RF structures for both the gun and linac, IFEL bunch compression, and short-period undulators. In this work, several stepping-stone, demonstrator scenarios under discussion for the UCLA SAMURAI Laboratory are detailed and simulated, employing different subsets of these elements. The cost, footprint, and technology risk for these scenarios are considered in addition to the anticipated engineering and physics experience gained.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB092

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paper received ※ 19 May 2021 paper accepted ※ 11 August 2021 issue date ※ 02 September 2021

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TUPAB099

Construction of an Infrared FEL at the Compact ERL

FEL, laser, operation, electron

1608

R. Kato, M. Adachi, S. Eguchi, K. Harada, N. Higashi, Y. Honda, T. Miyajima, S. Nagahashi, N. Nakamura, K.N. Nigorikawa, T. Nogami, T. Obina, H. Sagehashi, H. Sakai, M. Shimada, T. Shioya, M. Tadano, R. Takai, O.A. Tanaka, Y. Tanimoto, K. Tsuchiya, T. Uchiyama, A. Ueda, M. Yamamoto
KEK, Ibaraki, Japan
R. Hajima
QST, Tokai, Japan
N.P. Norvell
SLAC, Menlo Park, California, USA
F. Sakamoto
Akita National College of Technology, Akita, Japan
M. Shimada
HSRC, Higashi-Hiroshima, Japan

Funding: Work supported by NEDO project "Development of advanced laser processing with intelligence based high-brightness and high-efficiency laser technologies (TACMI project)".
The compact Energy Recovery Linac (cERL) has been in operation at KEK since 2013 to demonstrate ERL performance and develop ERL technology. Recently KEK has launched an infrared FEL project with a competitive funding. The purpose of this project is to build a mid-infrared FEL at the cERL, and to use that FEL as a light source for construction of the processing database required for industrial lasers. The FEL system is composed of two 3-m undulators and a matching section between them, and generates light with a maximum pulse energy of 0.1 micro-J at the wavelength of 20 microns with an 81.25 MHz repetition rate. The FEL is also expected to become a proof-of-concept machine for ERL base FELs for future EUV lithography.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB099

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paper received ※ 20 May 2021 paper accepted ※ 14 June 2021 issue date ※ 29 August 2021

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TUPAB100

FEL Design Elements of SABINA: A Free Electron Laser For THz-MIR Polarized Radiation Emission

radiation, electron, FEL, simulation

1612

F. Dipace, E. Chiadroni, M. Ferrario, A. Ghigo, L. Giannessi, A. Giribono, L. Sabbatini, C. Vaccarezza
INFN/LNF, Frascati, Italy
A. Doria, A. Petralia
ENEA C.R. Frascati, Frascati (Roma), Italy
S. Lupi
Sapienza University of Rome, Roma, Italy
S. Macis
La Sapienza University of Rome, Rome, Italy
V. Petrillo
Universita’ degli Studi di Milano, Milano, Italy
V. Petrillo
INFN-Milano, Milano, Italy

Funding: SABINA is a project co-funded by Regione Lazio within POR-FESR 2014-2020 program.
SABINA, acronym of "Source of Advanced Beam Imaging for Novel Applications", will be a Self-Amplified Spontaneous Emission Free Electron Laser (SASE FEL) providing a wide spectral range (from THz to MIR) of intense, short and variable polarization pulses for investigation in physics, chemistry, biology, cultural heritage, and material science. In order to reach these goals high brightness electron beams within a 30-100 MeV energy range, produced at SPARC photo-injector, will be transported up to an APPLE-X undulator through a dogleg. Space charge effects and Coherent Synchrotron Radiation (CSR) effects must be held under control to preserve beam quality. Studies on beam transport along the undulator and of the properties of the radiation field have been performed with "Genesis 1.3" simulation code. A downstream THz optics photon delivery system has also been designed to transport radiation on the long path from the undulator exit up to user experimental area.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB100

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paper received ※ 19 May 2021 paper accepted ※ 11 June 2021 issue date ※ 02 September 2021

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TUPAB101

Monte Carlo Simulations and Neutron and Gamma Fluence Measurements to Investigate Stray Radiation in the European XFEL Undulator System

electron, radiation, simulation, neutron

1615

O.E. Falowska-Pietrzak, A. Hedqvist, F. Hellberg
Stockholm University, Stockholm, Sweden
N. Bassler
DCPT, Aarhus N, Denmark
A. Leuschner, D. Nölle
DESY, Hamburg, Germany
F. Wolff-Fabris
EuXFEL, Schenefeld, Germany

The European X-ray Free Electron Laser (XFEL) is an user facility research centre generating extremely bright and ultra-short SASE x-ray pulses. The laser flashes are generated when electrons of GeV energies pass the undulator systems. Even if the dominating contribution of the radiation field in the undulator is from spontaneous undulator radiation, also electron losses can be observed, e.g. during beam steering or due to beam halo, not captured by the upstream collimation system. The interactions of those particles with the vacuum vessel wall result in the emission of stray radiation. The LB 6419 detector allows to measure both the neutron and the gamma component in the pulsed radiation fields nearby the undulators*. Usually, the real-time measurements show the dominance of the gamma signals. However, in case of particle loss occurs, a neutron signal is observed. In addition, Monte Carlo (MC) simulations conducted using the Geant4 code indicate that neutrons are also present within the undulator’s magnets volume. In this work, we present the LB 6419 measurement data and compare these to our MC simulations, to characterize the radiation field nearby the undulator segment.
* KLETT, A., LEUSCHNER, A., TESCH, N., A dose meter for pulsed neutron fields, Radiat Meas 45 (2010) 1242-1244

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB101

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paper received ※ 19 May 2021 paper accepted ※ 02 June 2021 issue date ※ 18 August 2021

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TUPAB104

Redesign of the FLASH2 Post-SASE Undulator Beamline

electron, quadrupole, photon, MMI

1626

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

FLASH2 is one of the two SASE (Self-Amplified Spontaneous Emission) undulator beamlines lines comprising variable gap undulators to produce radiation in the XUV and soft X-ray regime at FLASH. Downstream of the SASE undulators the beamline is currently undergoing a major redesign. During shutdowns in summer 2020 and winter 2021 two PolariX TDSs (Polarizable X-band Transverse Deflecting Structure) were installed, as well as additional diagnostics, to monitor the longitudinal phase space density of the electron bunches. Additionally, an afterburner undulator will be integrated in the next shutdown to produce circularly polarized light with wavelengths down to 1.39 nm. In this paper, we will present the modifications that were and will be made to the electron beamline in the course of this redesign.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB104

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paper received ※ 19 May 2021 paper accepted ※ 21 July 2021 issue date ※ 23 August 2021

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TUPAB106

Simulation Calculations of Compact THz Facility at IUAC, New Delhi

radiation, simulation, electron, optics

1633

J. Karmakar, S. Ghosh
IUAC, New Delhi, India

A compact THz radiation source based on the principle of pre-bunched Free Electron Laser is at the commissioning stage at Inter University Accelerator Centre (IUAC), New Delhi. The facility will generate low emittance train of electron micro-bunches (2, 4, 8 or 16 numbers) from a RF photo-cathode gun in the energy range of 4 to 8 MeV and inject into a compact undulator to generate coherent THz radiation in the frequency range of ~0.18 to 3.0 THz. To optimize the intensity at a given frequency, the beam bunching factor and the betatron oscillation amplitude in the non-wiggling plane of the electronμbunches inside the undulator has been maximized and minimized respectively. The paper presents the optimized beam optics simulation results for two frequencies viz 0.5 and 2 THz. The on-axis radiation spectral intensity computed by in-house developed code using the trajectory data of the beam optics simulation is also presented for the two frequencies.

Poster TUPAB106 [1.208 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB106

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paper received ※ 18 May 2021 paper accepted ※ 31 August 2021 issue date ※ 12 August 2021

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TUPAB107

Accelerator and Light Source Research Program at Duke University

FEL, polarization, storage-ring, electron

1636

Y.K. Wu
FEL/Duke University, Durham, North Carolina, USA

Funding: This work is supported in part by the US DOE grant no. DE-FG02-97ER41033.
The accelerator and light source research program at Duke Free-Electron Laser Laboratory (DFELL), TUNL, is focused on the development of the storage ring based free-electron lasers (FELs) and a state-of-the-art Compton gamma-ray source, the High Intensity Gamma-ray Source (HIGS) driven by the storage ring FEL. With a maximum total flux of about 3·10¹⁰ gamma/s and a spectral flux of more than 1,000 gamma/s/eV around 10 MeV, the HIGS is the world’s highest-flux Compton gamma-ray source. Operated in the energy range from 1 to 100 MeV, the HIGS is a premier Compton gamma-ray facility in the world for a variety of nuclear physics research programs, both fundamental and applied. In this work, we will describe our recent light source development to enable the production of gamma rays in the higher energy range from 100 and 120 MeV. We will also provide a summary of our recent accelerator physics and FEL physics research activities.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB107

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paper received ※ 26 May 2021 paper accepted ※ 14 July 2021 issue date ※ 15 August 2021

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TUPAB109

Characterization of the X-Ray Angular Pointing Jitter in the LCLS Hard X-ray Undulator Line

FEL, electron, cavity, detector

1640

R.A. Margraf, Z. Huang, J.P. MacArthur, G. Marcus, T. Sato, D. Zhu
SLAC, Menlo Park, California, USA
Z. Huang
Stanford University, Stanford, California, USA

Funding: This work was supported by the Department of Energy, Laboratory Directed Research and Development program at SLAC National Accelerator Laboratory, under contract DE-AC02-76SF00515.
The angular pointing jitter of X-ray pulses produced by an X-ray Free-Electron Laser (XFEL) depends on both intrinsic properties of the SASE (Self-amplified spontaneous emission) process and jitters in beamline variables such as electron orbit. This jitter is of interest to the Cavity-Based XFEL (CBXFEL)* project at SLAC, which will lase seven undulators inside an X-ray cavity of four diamond Bragg mirrors. The CBXFEL cavity has a narrow angular bandwidth, thus large angular jitters cause X-rays to leak out of the cavity and degrade cavity efficiency. To understand contributors to angular pointing jitter, we studied the pointing jitter of the Linac Coherent Light Source (LCLS) Hard X-ray Undulator line (HXU). Monochromatic and pink X-rays were characterized at the X-ray Pump Probe (XPP) instrument. We found pulses with high monochromatized pulse energy and small electron beam orbit in the undulator have the lowest angular pointing jitter. We present here our measurement results, discuss why these factors correlate with pointing stability, and propose a strategy for CBXFEL to reduce angular pointing jitter and account for angular pointing jitter in cavity efficiency measurements.
*Gabriel Marcus et al. "CBXFEL Physics Requirements Document for the Optical cavity Based X-Ray Free Electron Lasers Research and Development Project." SLAC-I-120-103-121-00. Apr 2020.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB109

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paper received ※ 19 May 2021 paper accepted ※ 14 June 2021 issue date ※ 14 August 2021

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TUPAB111

Layout of the Laser Heater for FLASH2020+

electron, laser, FEL, free-electron-laser

1647

C. Gerth, E. Allaria, A. Choudhuri, L. Schaper, E. Schneidmiller, S. Schreiber, M. Tischer, P. Vagin, M. Vogt, L. Winkelmann, M.V. Yurkov, J. Zemella
DESY, Hamburg, Germany

The major upgrade FLASH2020+ of the FEL user facility FLASH includes an improved injector layout for the generation of the high-brightness electron beam as well as an externally seeded FEL beamline. Microbunching gain of initial modulations or shot-noise fluctuations degrade the electron beam quality, which is in particular harmful to the external seed process. To minimize the microbunching gain by a controlled increase of the uncorrelated energy spread, the installation of a laser heater is foreseen directly upstream of the first bunch compression chicane. In this paper, we present the layout of the laser heater section, which follows the original proposal published almost 20 years ago and differs in several aspects from the common layout implemented at many other FEL facilities. The considerations that have been made for the optimisation of the laser heater parameters are described in detail.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB111

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paper received ※ 19 May 2021 paper accepted ※ 07 July 2021 issue date ※ 01 September 2021

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TUPAB113

Highlights From the Conceptual Design Report of the Soft X-Ray Laser at MAX IV

FEL, electron, laser, linac

1651

F. Curbis, J. Andersson, L. Isaksson, B.S. Kyle, F. Lindau, E. Mansten, H. Tarawneh, P.F. Tavares, S. Thorin, A.S. Vorozhtsov
MAX IV Laboratory, Lund University, Lund, Sweden
S. Bonetti
Stockholm University, Stockholm, Sweden
V.A. Goryashko, P.M. Salén
Uppsala University, Uppsala, Sweden
P. Johnsson, S.P. Pirani, M.A. Pop, W. Qin, S. Werin
Lund University, Lund, Sweden
M. Larsson
Stockholm University, Department of Physics, Stockholm, Sweden
A. Nilsson
FYSIKUM, AlbaNova, Stockholm University, Stockholm, Sweden
J.A. Sellberg
KTH Physics, Stockholm, Sweden

Funding: Knut and Alice Wallenberg Foundation
The SXL (Soft X-ray Laser) project developed a conceptual design for a soft X-ray Free Electron Laser in the 1–5 nm wavelength range, driven by the existing MAX IV 3 GeV linac. In this contribution we will focus on the FEL operation modes developed for the first phase of the project based on two different linac modes. The design work was supported by the Knut and Alice Wallenberg foundation and by several Swedish universities and organizations (Stockholm, Uppsala, KTH Royal Institute of Technology, Stockholm-Uppsala FEL center, MAX IV laboratory and Lund University).

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB113

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paper received ※ 19 May 2021 paper accepted ※ 17 June 2021 issue date ※ 19 August 2021

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TUPAB114

FEL Performance and Beam Quality Assessment of Undulator Line for the CompactLight Facility.

FEL, brilliance, photon, electron

1655

H.M. Castañeda Cortés, D.J. Dunning, N. Thompson
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Funding: H2020 CompactLight has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No. 777431
The H₂020 CompactLight Project aims for the design of innovative, cost-effective, compact FEL facilities to generate higher peak brilliance radiation in the soft and hard X-ray. In this paper we assess via simulation studies the performance of a variably polarising APPLE-X afterburner positioned downstream of a helical Super Conducting Undulator (SCU). We discuss the optimum balance between the active SCU length and the afterburner length, considering the peak brilliance and pulse energy of the output. Our studies are complemented with analysis of the optical beam quality of the afterburner output to determine the design constraints of the photon beamline that delivers the FEL output to the experimental areas.
* Mak, A., Salen, P., Goryashko, V., Clarke, J., http://uu.diva-portal.org/smash/record.jsf?pid=diva2\%3A1280300&dswid=3236
** Lutman, A. et al. Nature Photonics 10, 468

Poster TUPAB114 [1.210 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB114

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paper received ※ 11 May 2021 paper accepted ※ 10 June 2021 issue date ※ 27 August 2021

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TUPAB115

Status Report of the Superconducting Free-Electron Laser FLASH at DESY

experiment, FEL, electron, operation

1659

J. Rönsch-Schulenburg, F. Christie, K. Honkavaara, M. Kuhlmann, S. Schreiber, R. Treusch, M. Vogt, J. Zemella
DESY, Hamburg, Germany

The free-electron laser in Hamburg (FLASH) is a high brilliance XUV and soft X-ray SASE FEL user-facility at DESY. FLASH’s superconducting linac can accelerate several thousand electron bunches per second in 10 Hz bursts of up to 800 µs length. The long bunch trains can be split in two parts and shared between two undulator beamlines. During 2020, FLASH supplied, in standard operation, up to 500 bunches at 10 Hz in two bunch trains with independent fill patterns and compression schemes. The FLASH2 undulator beamline comprises variable gap undulators that allow different novel lasing schemes. A third beamline accommodates the FLASHForward plasma wakefield acceleration experiment. We report on the FLASH operation in 2019 - 2021 and present a few highlights.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB115

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paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 19 August 2021

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TUPAB116

Toward THz Coherent Undulator Radiation Experiment with a Combination of Velocity Bunchings

radiation, electron, bunching, acceleration

1663

Y. Sumitomo, K. Hayakawa, Y. Hayakawa, K. Nogami, T. Sakai, T. Tanaka
LEBRA, Funabashi, Japan

Funding: Japan Society for the Promotion of Science (JSPS), Grant-in-Aid for Scientific Research (KAKENHI), Grant Number JP19K12631.
We have launched a research program to generate the THz coherent undulator radiations, following the proposal of the combination of velocity bunchings * at Nihon University. The combination of velocity bunchings is an efficient way of bunch compression allowing a range of energy choices, in other words, a range of quasi-monochromatic radiation wavelengths generated at the undulator. In addition to the existing wideband THz light sources (0.1 - 2 THz) by the coherent edge and transition radiations currently available at Nihon Univ., the development of a high peak-power and quasi-monochromatic coherent radiation should accelerate the activities including the material science related to the THz bandwidths. In this presentation, we illustrate the program and report the current status of the experiment.
* Y. Sumitomo et al., J. Phys. Conf. Ser., vol. 1067, p. 032017, 2018.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB116

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paper received ※ 19 May 2021 paper accepted ※ 15 June 2021 issue date ※ 15 August 2021

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TUPAB119

Beam Loss Study for the Implementation of Dechirper at the European XFEL

FEL, radiation, simulation, electron

1670

J.J. Guo
University of Chinese Academy of Sciences, Beijing, People’s Republic of China
W. Decking, M.W. Guetg, J.J. Guo, S. Liu, W. Qin, I. Zagorodnov
DESY, Hamburg, Germany
Q. Gu, J.J. Guo
SINAP, Shanghai, People’s Republic of China
Q. Gu
Shanghai Advanced Research Institute, Pudong, Shanghai, People’s Republic of China

The European XFEL is a free-electron laser facility based on superconducting linac with high repetition rate up to 4.5 MHz. Wakefield structure (also called dechirper module) is planned to be installed in front of the SASE beam line at the European FEL, which can be used as a kicker for two-color scheme or a dechirper to control the bandwidth of SASE radiation. When the beam pass through the dechirper module, strong longitudinal and transverse wakefields can be excited to introduce a correlated energy chirp and a kick along the bunch. However, due to the relatively small gap of dechirper, beam halo particles hitting the dechirper module can lead to energy deposition and generate additional radiation, which can cause serious damage to the downstream undulators. For this reason, simulations have been performed using BDSIM to define the maximum acceptable beam halo, and the results are presented in this paper.

Poster TUPAB119 [1.489 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB119

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paper received ※ 16 May 2021 paper accepted ※ 15 June 2021 issue date ※ 12 August 2021

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TUPAB122

SASE3 Variable Polarization Project at the European XFEL

polarization, vacuum, FEL, electron

1678

S.K. Karabekyan, S. Abeghyan, M. Bagha-Shanjani, S. Casalbuoni, U. Englisch, G. Geloni, J. Grünert, S. Hauf, C. Holz, D. La Civita, J. Laksman, D. Mamchyk, M.P. Planas, F. Preisskorn, S. Serkez, H. Sinn, A. Violante, G. Wellenreuther, M. Wuenschel, M. Yakopov, C. Youngman
EuXFEL, Schenefeld, Germany
A. Block, W. Decking, N. Golubeva, K. Knebel, T. Ladwig, D.L. Lenz, D. Lipka, R. Mattusch, N. Mildner, E. Negodin, D. Nölle, J. Prenting, F. Saretzki, M. Schlösser, F. Schmidt-Föhre, E. Schneidmiller, D. Thoden, T. Wamsat, S. Wendt, T. Wilksen, T. Wohlenberg, M.V. Yurkov
DESY, Hamburg, Germany
M. Brügger, M. Calvi, S. Danner, R. Ganter, L. Huber, A. Keller, M.S. Schmidt, T. Schmidt
PSI, Villigen PSI, Switzerland
D.E. Kim
PAL, Pohang, Republic of Korea
Y. Li
IHEP, People’s Republic of China

At the European XFEL, two undulator systems for hard and one for soft X-rays have been successfully put into operation. The SASE3 soft X-ray undulator system generates linearly polarized radiation in the horizontal plane. One of the requirements for extending the radiation characteristics is the ability to obtain different polarization modes. These include both right and left circular, elliptical polarization, or linear polarization at an arbitrary angle. For this purpose, a system consisting of four APPLE X helical undulators developed at the Paul Scherrer Institute (PSI) is used. This paper presents the design parameters of the SASE3 undulator system after modifying it with the helical afterburner. It also describes the methods and the design solutions different from those used at PSI. The status and schedule of the project are introduced.

Poster TUPAB122 [0.553 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB122

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paper received ※ 19 May 2021 paper accepted ※ 31 May 2021 issue date ※ 27 August 2021

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TUPAB125

Studies of Particle Losses From the Beam in the EU-XFEL Following Scattering by a Slotted Foil

radiation, FEL, simulation, diagnostics

1681

A.T. Potter, A. Wolski
The University of Liverpool, Liverpool, United Kingdom
W. Decking, S. Liu
DESY, Hamburg, Germany
F. Jackson
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

One technique for producing short radiation pulses in an FEL involves the use of a slotted foil in a bunch compressor. However, the scattering of particles from the foil can lead to increased particle losses and the generation of secondary particles. This is a particular concern for high rep-rate FELs, such as the European XFEL, where there are plans to implement the slotted-foil technique for short pulse generation. The study reported here aims to characterise the impact of a slotted foil in the European XFEL on the radiation dose in the front section of one of the undulators. Simulations were performed using BDSIM: this code tracks primary particles along the beamline, models the interaction between particles and accelerator components and tracks secondary particles produced by these interactions. The results indicate the amount of energy deposited in the front section of one of the FEL undulators, and provide a basis for optimisation of the collimation system to keep the energy deposition and radiation doses within acceptable limits.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB125

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paper received ※ 19 May 2021 paper accepted ※ 10 June 2021 issue date ※ 28 August 2021

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TUPAB129

Beam Based Alignment in a Compact THz-FEL Facility

quadrupole, FEL, alignment, linac

1692

Q.S. Chen, T. Hu, K.F. Liu, B. Qin, Y.Q. Xiong
HUST, Wuhan, People’s Republic of China

In this paper, we presented the beam based alignment results in a compact THz-FEL facility. The alignment was divided into two sections, the transport line and the optical line. In the transport line, all the five quadrupoles upstream of the undulator were adjusted one by one to fit the electron beam from the traveling wave linac. In the optical line, a set of auxiliary coils were winded on the yokes of the quadrupole downstream of the double bend achromat (DBA) to produce a vertical steering force. Another combined steering magnet, together with the auxiliary coils, corrected the beam orbit in the optical line. With the dispersion free test, the displacement between the magnetic centers of the quads and the beam orbit was less than 0.1mm.

Poster TUPAB129 [0.673 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB129

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paper received ※ 18 May 2021 paper accepted ※ 17 June 2021 issue date ※ 27 August 2021

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TUPAB217

Effect of Undulators on Transverse Resonant Island Orbits

operation, diagnostics, dipole, optics

1927

E.C.M. Rial, J. Bahrdt, P. Goslawski, A. Meseck, M. Ries, M. Scheer
HZB, Berlin, Germany

For one week in October 2020, BESSY II offered a Two Orbit mode to users for the first time*. In this Two Orbit mode, the existence of transverse resonant island buckets** are exploited to store a second beam in the storage ring as an ’island orbit’, away from the primary beam axis. This mode was offered with free range of motion of the 12 out of vacuum undulators installed at the BESSY II ring. Diagnostics of the island orbit were limited to a single camera monitoring bending magnet radiation from a single dipole. A significant motion of the island orbit was observed on this diagnostic and correlated with undulator motion. This observation is reported, and simulations presented to demonstrate how this motion could arise. Correction schemes are suggested and discussed.
*Two Orbit - a report on the first scheduled week of TRIBs user operation at BESSY II, M. Ries et al, these proceedings
**Proc. IPAC 2016, Busan, S Korea, paper THPMR017, p. 3427

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB217

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paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 22 August 2021

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TUPAB267

Investigation of Beam Impedance and Heat Load in a High Temperature Superconducting Undulator

impedance, laser, simulation, site

2089

D. Astapovych, H. De Gersem, E. Gjonaj
TEMF, TU Darmstadt, Darmstadt, Germany
T.A. Arndt, E. Bründermann, N. Glamann, A.W. Grau, B. Krasch, A.-S. Müller, R. Nast, D. Saez de Jauregui, A. Will
KIT, Eggenstein-Leopoldshafen, Germany

The use of high temperature superconducting (HTS) materials can enhance the performance of superconducting undulators (SCU), which can later be implemented in free electron laser facilities, synchrotron storage rings and light sources. In particular, the short period < 10 mm undulators with narrow magnetic gap < 4 mm are relevant. One of the promising approaches considers a 10 cm meander-structured HTS tapes stacked one above the other. Then, the HTS tape is wound on the SCU. The idea of this jointless undulator has been proposed by, and is being further developed at KIT. Since minimizing the different sources of heat load is a critical issue for all SCUs, a detailed analysis of the impedance and heat load is required to meet the cryogenic system design. The dominant heat source is anticipated to be the resistive surface loss, which is one of the subjects of this study. Considering the complexity of the HTS tape, the impedance model includes the geometrical structure of the HTS tapes as well as the anomalous skin effect. The results of the numerical investigation performed by the help of the CST PS solver will be presented and discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB267

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paper received ※ 18 May 2021 paper accepted ※ 26 July 2021 issue date ※ 12 August 2021

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TUPAB373

Design of a Delta-type Superconducting Undulator at the IHEP

polarization, photon, permanent-magnet, radiation

2391

J.H. Wei
IHEP CSNS, Guangdong Province, People’s Republic of China
C.D. Deng
DNSC, Dongguan, People’s Republic of China
L. Gong, X.Y. Li, X.C. Yang
IHEP, Beijing, People’s Republic of China
Y. Li
DESY, Hamburg, Germany

Undulators play an important role in the 4th generation radiation light source. In order to satisfy different requirements of the experiments, various undulator structures have been proposed. The Delta-type undulator can provide circular polarized radiation. Conventional undulators are usually made of permanent magnets, but the application of the superconducting technology in the undulator is developing quickly. Compared to the permanent magnet undulators, superconducting undulators can provide higher photon flux with the same magnetic pole gap and period length, especially when the period length is longer than 20 mm. An R&D project is underway to produce a protype of a Delta-type superconducting undulator with 28 mm long period and 12 mm gap at the IHEP. The structure design and the simulation results of the magnetic field are presented in this paper.

Poster TUPAB373 [1.752 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB373

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paper received ※ 19 May 2021 paper accepted ※ 18 June 2021 issue date ※ 15 August 2021

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WEXC05

First Results Operating a Long-Period EPU in Universal Mode at the Canadian Light Source

polarization, photon, focusing, injection

2566

W.A. Wurtz, C.K. Baribeau, D. Bertwistle, M.J. Sigrist
CLS, Saskatoon, Saskatchewan, Canada

The Quantum Materials Spectroscopy Centre beamline at the Canadian Light Source (CLS) requires photons with energies as low as 15 eV with circular polarization at the end station. This energy range is accomplished on the 2.9 GeV CLS storage ring using an elliptically polarizing undulator (EPU) with a 180 mm period, which we call EPU180. In order to realize circular polarized photons at the end station with this low energy, we must overcome two technical issues. First, the beamline optics distort the polarization of the light, so we compensate by providing light with a flattened, tilted polarization ellipse at the source point - a mode of operation known as universal mode. Second, the device has a strong effect on the electron beam due to dynamic focusing and is capable of reducing the injection efficiency to zero. We overcome this non-linear dynamic focusing using current strips adhered to the vacuum chamber. In this report, we present the first results with operating EPU180 in universal mode and we recover the dynamic aperture using the current strips.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEXC05

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paper received ※ 13 May 2021 paper accepted ※ 05 July 2021 issue date ※ 11 August 2021

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WEPAB087

Observation of Undulator Radiation Generated by a Single Electron Circulating in a Storage Ring and Possible Applications

synchrotron, electron, radiation, photon

2790

I. Lobach
University of Chicago, Chicago, Illinois, USA
A. Halavanau, Z. Huang
SLAC, Menlo Park, California, USA
K. Kim
ANL, Lemont, Illinois, USA
S. Nagaitsev, A.L. Romanov, G. Stancari, A. Valishev
Fermilab, Batavia, Illinois, USA

An experimental study into the undulator radiation, generated by a single electron was carried out at the Integrable Optics Test Accelerator (IOTA) storage ring at Fermilab. The individual photons were detected by a Single Photon Avalanche Diode (SPAD) at an average rate of 1 detection per 300 revolutions in the ring. The detection events were continuously recorded by a picosecond event timer for as long as 1 minute at a time. The collected data were used to test if there is any deviation from the classically predicted Poissonian photostatistics. It was motivated by the observation * of sub-Poissonian statistics in a similar experiment. The observation * could be an instrumentation effect related to low detection efficiency and long detector dead time. In our experiment, the detector (SPAD) has a much higher efficiency (65%) and a much lower dead time. In addition, we show that the collected data (recorded detection times) can be used to study the synchrotron motion of a single electron and infer some parameters of the ring. For example, by comparing the results of simulation and measurement for the synchrotron motion we were able to estimate the magnitude of the RF phase jitter.
* Teng Chen and John M. J. Madey, Phys. Rev. Lett. 86, 5906, June 2001

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB087

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paper received ※ 17 May 2021 paper accepted ※ 24 June 2021 issue date ※ 16 August 2021

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WEPAB088

Transverse Beam Emittance Measurement by Undulator Radiation Power Noise

radiation, emittance, optics, synchrotron

2794

I. Lobach
University of Chicago, Chicago, Illinois, USA
A. Halavanau, Z. Huang
SLAC, Menlo Park, California, USA
K. Kim
ANL, Lemont, Illinois, USA
V.A. Lebedev, S. Nagaitsev, A.L. Romanov, G. Stancari, A. Valishev
Fermilab, Batavia, Illinois, USA

Generally, turn-to-turn power fluctuations of incoherent spontaneous synchrotron radiation in a storage ring depend on the 6D phase-space distribution of the electron bunch. In some cases, if only one parameter of the distribution is unknown, this parameter can be determined from the measured magnitude of these power fluctuations. In this contribution, we report the results of our experiment at the Integrable Optics Test Accelerator (IOTA) storage ring, where we carried out an absolute measurement (no free parameters or calibration) of a small vertical emittance (5–15 nm rms) of a flat beam by this new method, under conditions, when the small vertical emittance is unresolvable by a conventional synchrotron light beam size monitor.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB088

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paper received ※ 17 May 2021 paper accepted ※ 24 June 2021 issue date ※ 12 August 2021

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WEPAB126

Pulsed Wire Magnetic Field Measurement System for Short-Period Long Undulators

FEL, laser, detector, electron

2903

J.E. Baader, S. Casalbuoni
EuXFEL, Schenefeld, Germany

The pulsed wire method is an attractive option to measure the magnetic field in insertion devices, mainly for those with restricted access (e.g., small gaps, in-vacuum/cryogenic environments, etc.). Besides first and second field integrals, experiments have proved the feasibility of reconstructing the magnetic field profile. Undulators with a small gap and short period are - and are planned to be - used at diffraction-limited storage rings and free-electron lasers. This contribution outlines the pulsed wire system’s requirements to perform magnetic field reconstruction in such undulators. We examine the main expected limitations, particularly the dispersive, finite pulse-width, discretization error, and sag effects. Furthermore, we present the current status of developing the pulsed wire system at the European XFEL.

Poster WEPAB126 [1.184 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB126

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paper received ※ 19 May 2021 paper accepted ※ 07 July 2021 issue date ※ 19 August 2021

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WEPAB127

Accurate Measurements of Undulator Particle Beam Entrance/Exit Angles Using Improved Hall Probes and Calibration Process

photon, insertion, insertion-device, closed-orbit

2907

I. Vasserman, R.J. Dejus, Y. Piao, M.F. Qian, J.Z. Xu
ANL, Lemont, Illinois, USA

Funding: Work supported by U.S. Department of Energy, Office of Science, under contract number DE-AC02-06CH11357.
The Advanced Photon Source Upgrade (APS-U) undulator requirements were changed from the first and second field integrals to the entrance and exit angles of the particle beam. This provides the user with the best radiation view angle by the storage ring closed orbit correction system. To satisfy such requirements we use improved Senis Hall probes and calibration process. In addition to the normal NMR calibration of the sensors, the calibration was further refined using stretch-coil integrals to make accurate measurements.

Poster WEPAB127 [0.620 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB127

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paper received ※ 15 May 2021 paper accepted ※ 09 June 2021 issue date ※ 19 August 2021

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WEPAB128

Recent Experience with Magnet Sorting for APS-U Hybrid Undulators

quadrupole, photon, permanent-magnet, synchrotron

2910

I. Vasserman, R.J. Dejus, Y. Piao, M.F. Qian, J.Z. Xu
ANL, Lemont, Illinois, USA

Funding: Work supported by U.S. Department of Energy, Office of Science, under contract number DE-AC02-06CH11357.
The quality of permanent magnets plays a particularly important role in undulator performance. Many different types of magnet sorting to enhance undulator performance have been carried out at different facilities. Meanwhile, progress in improving magnet quality has been made by different vendors. At the Advanced Photon Source (APS) we have assembled, measured, and analyzed over 14 new undulators of the same mechanical design, some of them with sorted magnets and some unsorted. The performance differences appear to be insignificant in meeting the tight APS Upgrade (APS-U) undulator requirements.

Poster WEPAB128 [0.395 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB128

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paper received ※ 16 May 2021 paper accepted ※ 09 June 2021 issue date ※ 10 August 2021

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WEPAB129

A New Method of Undulator Phase Tuning with Mechanical Shimming

MMI, radiation, operation, permanent-magnet

2912

M.F. Qian, R.J. Dejus, Y. Piao, I. Vasserman, J.Z. Xu
ANL, Lemont, Illinois, USA

Funding: Work supported by U.S. Department of Energy, Office of Science, under contract number DEAC02-06CH11357.
We developed a new method for tuning the undulator phase errors by shimming the undulator gap profile mechanically. First, the phase errors of a device are calculated based on the initial field measurement; then the desired field strength modulation along the device length is derived from the phase errors; and finally, the gap profile is mechanically shimmed to produce the desire field strength modulation. The method has been successfully applied to the tuning of many new and reused APS Upgrade (APS-U) hybrid permanent magnet undulators. The method is especially effective for tuning the legacy undulators with large phase errors. For instance, an old 33-mm-period undulator with a 23 degree initial rms phase error largely due to radiation damage has been tuned to better than 3 degrees.

Poster WEPAB129 [0.500 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB129

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paper received ※ 19 May 2021 paper accepted ※ 24 June 2021 issue date ※ 13 August 2021

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WEPAB130

Experience with Algorithm-Guided Tuning of APS-U Undulators

radiation, MMI, electron, permanent-magnet

2915

M.F. Qian, R.J. Dejus, Y. Piao, I. Vasserman, J.Z. Xu
ANL, Lemont, Illinois, USA

Funding: Work supported by U.S. Department of Energy, Office of Science, under contract number DE AC02-06CH11357.
The Advanced Photon Source (APS) is undergoing a major upgrade to its storage ring. The APS Upgrade (APS-U) project plans to build over 40 new hybrid permanent magnet undulators (HPMUs) and rebuild over 20 existing HPMUs. To meet the APS-U undulator requirements, the quality of the undulator magnetic field needs to be fine-tuned to the specifications. The traditional methods that depend on the tuning specialist experience are not desirable for tuning large quantities of undulators. We developed algorithms that automate the tuning of permanent magnet undulators. For tuning of the undulator trajectory and phase, the algorithms optimize the tuning parameters with differential evolution-based global optimization. The algorithms have been successfully applied to over 18 APS HPMUs. The results and experiences of the tuning are reported in detail.

Poster WEPAB130 [0.543 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB130

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paper received ※ 19 May 2021 paper accepted ※ 24 June 2021 issue date ※ 12 August 2021

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WEPAB131

Magnetic Tuning and Installation Modifications of U48 Undulator for the Delhi Light Source (DLS)

electron, controls, vacuum, focusing

2918

M. Tischer, P. Neumann, A. Schöps, P. Vagin, T. Vielitz, T. Wohlenberg
DESY, Hamburg, Germany
M. Aggarwal, R.N. Dutt, S. Ghosh, J. Karmakar, S. Sahu
IUAC, New Delhi, India
J. Bahrdt, E.C.M. Rial
HZB, Berlin, Germany

A compact THz radiation facility based on the principle of a pre-bunched Free Electron Laser, called Delhi Light Source (DLS) is at the final stage of commissioning at IUAC, New Delhi, India. For generation of THz radiation in DLS, an undulator with period length of 48 mm (U48), built by HZB and refurbished at DESY will be used. The magnetic tuning and the field measurements have been done on the U48 along with the design and installation of correction coils at the entrance/exit of the U48. In addition, horizontal and vertical ambient field correction coils were integrated into the magnet girders. A quadrupole correction coil along the vacuum chamber in order to mitigate the defocusing effect of the U48 on the electron beam has been designed. The current through all coils has been adjusted as a function of the gap by the new control system designed for the U48. In addition, an extruded aluminium vacuum chamber was designed and fabricated and will be aligned with the the undulator soon.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB131

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paper received ※ 19 May 2021 paper accepted ※ 05 July 2021 issue date ※ 11 August 2021

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WEPAB132

Towards a Superconducting Undulator Afterburner for the European XFEL

FEL, photon, electron, vacuum

2921

S. Casalbuoni, J.E. Baader, G. Geloni, V. Grattoni, D. La Civita, C. Lechner, B. Marchetti, S. Serkez, H. Sinn
EuXFEL, Schenefeld, Germany
W. Decking, L. Lilje, S. Liu, T. Wohlenberg, I. Zagorodnov
DESY, Hamburg, Germany

We propose to develop, characterize and operate a superconducting undulator (SCU) afterburner consisting of 5 undulator modules (1 module = 2 times SCU coil of 2 m length and 1 phase shifter) at the SASE2 hard X-ray beamline of European XFEL. This afterburner has the potential to produce an output of more than 10¹⁰ ph/pulse at photon energies above 30 keV. The project is divided into the production of a pre-series prototype module and a small-series production of 5 modules. Central goals of this R&D activity are: the demonstration of the functionality of SCUs at an X-ray FEL, the set up of the needed infrastructure to characterize and operate SCUs, the industrialization of such undulators, and the reduction of the price per module. In this contribution, the main parameters and specifications of the pre-series prototype module (S-PRESSO) are described.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB132

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paper received ※ 15 May 2021 paper accepted ※ 05 July 2021 issue date ※ 14 August 2021

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WEPAB133

First Numerical Wakefield Studies of New In-Vacuum Cryogenic and APPLE II Undulators for BESSY II

impedance, simulation, vacuum, factory

2925

M. Huck, J. Bahrdt, A. Meseck
HZB, Berlin, Germany
A. Meseck
KPH, Mainz, Germany

While the new in-vacuum cryogenic undulator is in its last commissioning stages, a worldwide new in-vacuum APPLE II undulator is being designed and constructed for BESSY II storage ring. Besides the challenging mechanical design of these small-gap and short-period undulators, challenges arise due to interaction with the electron beam. Therefore, detailed studies of this interaction is required to minimize the adverse effects on beam dynamics and the device itself. For this purpose, the wakefield effects have been computed numerically for critical parts of these devices i.e. the RF-shields, flexible tapers and taper sections. A brief overview of simulation results and discussions are presented in this paper.

Poster WEPAB133 [0.795 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB133

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paper received ※ 19 May 2021 paper accepted ※ 23 July 2021 issue date ※ 23 August 2021

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WEPAB134

Experimental Studies of the In-Vacuum-Cryogenic Undulator Effect on Beam Instabilities at BESSY II

vacuum, feedback, damping, impedance

2929

M. Huck, J. Bahrdt, A. Meseck, G. Rehm, M. Ries, A. Schälicke
HZB, Berlin, Germany

A new in-vacuum cryogenic permanent magnet undulator (CPMU17) has been installed in summer 2018 in the BESSY II storage ring at HZB. Such a small gap in-vacuum undulator device increases the impedance of the storage ring and can contribute to the instabilities that adversely affect the beam quality and the device itself. To identify and explore the effects of CPMU17 on the instabilities at BESSY II, grow-damp and drive-damp experiments have been conducted using the installed bunch-by-bunch feedback system. In this paper, the first results of the mode and gap analysis of these studies with a brief overview of other impedance studies will be presented.

Poster WEPAB134 [1.079 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB134

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paper received ※ 17 May 2021 paper accepted ※ 02 July 2021 issue date ※ 23 August 2021

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WEPAB135

Progress of the Development of a Superconducting Undulator as a THz Source for FELs

radiation, FEL, electron, experiment

2933

J. Gethmann, S. Casalbuoni, N. Glamann, A.W. Grau, A.-S. Müller, D. Saez de Jauregui
KIT, Karlsruhe, Germany
D. Astapovych, H. De Gersem, E. Gjonaj
TEMF, TU Darmstadt, Darmstadt, Germany
S. Casalbuoni
EuXFEL, Schenefeld, Germany

Funding: This work is supported by the BMBF project 05K19VK2 SCUXFEL (Federal Ministry of Education and Research) and by the DFG-funded Doctoral School KSETA: Science and Technology.
To produce radiation in the THz frequency range at X-ray Free Electron Lasers, undulators with large period length, high fields, and large gaps are required. These demands can be fulfilled by superconducting undulators. In this contribution, the actual requirements on the main parameters of such a superconducting undulator will be discussed and the progress of the design will be discussed. In addition, beam impedance and heat load results obtained analytically as well as by large-scale wakefield simulations will be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB135

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paper received ※ 19 May 2021 paper accepted ※ 02 July 2021 issue date ※ 31 August 2021

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WEPAB251

Beam Dynamics Optimization of LCLS-II HE Linear Accelerator Design

emittance, electron, radiation, FEL

3224

J. Qiang
LBNL, Berkeley, California, USA
T.O. Raubenheimer, M.D. Woodley
SLAC, Menlo Park, California, USA

The LCLS-II-HE as a high energy upgrade of the high repetition rate X-ray FEL under construction at SLAC will provide great opportunities for scientific discovery by generating coherent, high brightness hard X-ray radiation. In this paper, we report on beam dynamics optimization of the LCLS-II HE linear accelerator design with a 100pC and a 20pC charge beam to attain high quality electron beam for X-ray FEL radiation. We also present preliminary results of beam dynamics optimization of a 100pC beam from a low emittance superconducting injector.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB251

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paper received ※ 18 May 2021 paper accepted ※ 21 June 2021 issue date ※ 30 August 2021

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WEPAB257

Matching of a Space-Charge Dominated Beam into the Undulator of the THz SASE FEL at PITZ

electron, experiment, quadrupole, FEL

3244

X. Li, Z. Aboulbanine, G.D. Adhikari, N. Aftab, Z.G. Amirkhanyan, P. Boonpornprasert, M.E. Castro Carballo, N. Chaisueb, G.Z. Georgiev, J. Good, M. Groß, C. Koschitzki, M. Krasilnikov, O. Lishilin, A. Lueangaramwong, D. Melkumyan, R. Niemczyk, A. Oppelt, H.J. Qian, G. Shu, F. Stephan, G. Vashchenko, T. Weilbach
DESY Zeuthen, Zeuthen, Germany

The Photo Injector Test facility at DESY in Zeuthen (PITZ) is developing a THz SASE FEL as a prototype high repetition rate accelerator-based source for the THz-pumped, X-ray-probed experiments at the European XFEL. For the generation of THz pulses of mJ-level energy from SASE, an electron beam with a high charge (up to 4 nC) and high peak current (~200 A) will be injected into an LCLS-I undulator, which is currently being installed at the end of the photo-injector. The narrow vacuum chamber (11x5 mm) between the magnetic poles and the strong vertical focusing from the undulator, as well as the lack of beam diagnostics, have made it a challenge to match the space-charge dominated beam into the undulator without beam loss during the following transport. In this paper, boundary conditions of a matched electron beam will be discussed and the simulation and experimental study on our matching strategy will be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB257

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paper received ※ 08 May 2021 paper accepted ※ 02 July 2021 issue date ※ 13 August 2021

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WEPAB270

Characterization and Simulation of Optical Delay System for the Proof-of-Principle Experiment of Optical Stochastic Cooling at IOTA

radiation, experiment, simulation, kicker

3269

A.J. Dick, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
J.D. Jarvis
Fermilab, Batavia, Illinois, USA
P. Piot
ANL, Lemont, Illinois, USA

Funding: CBB NSF-PHY-1549132 DOE DE-SC0018656 DOE DE-AC02-07CH11359
The Optical Stochastic Cooling (OSC) experiment at Fermilab’s IOTA storage ring uses two undulators to cool the beam over many turns. The radiation emitted by electrons in the first undulator is delayed and imaged in the second undulator where it applies a corrective energy kick on the electrons. Imperfections in the manufacturing of the delay plates can lead to a source of error. This paper presents the experimental characterization of the absolute thickness of these delay plates using an interferometric technique. The measured "thickness maps" are implemented in the Synchrotron Radiation Workshop (SRW) program to assess their impact on the delayed radiation pulse.

Poster WEPAB270 [2.578 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB270

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paper received ※ 16 May 2021 paper accepted ※ 05 July 2021 issue date ※ 22 August 2021

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WEPAB271

Numerical Modelling of the Optical Stochastic Cooling Experiment at IOTA

simulation, radiation, damping, emittance

3273

A.J. Dick, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
J.D. Jarvis
Fermilab, Batavia, Illinois, USA
P. Piot
ANL, Lemont, Illinois, USA

Funding: CBB NSF-PHY-1549132 DOE DE-SC0018656 DOE DE-AC02-07CH11359
A proof-of-principle optical-stochastic cooling (OSC) experiment is currently in its commissioning phase at the Fermilab’s IOTA ring. In support of this experiment, we recently implemented an OSC element in the ELEGANT tracking program. The model, based on a semi-analytic description of OSC [*], supports the simulation of a large number of macroparticles (10⁴-10⁶) over many turns (10⁶). This paper showcases the simulation capabilities to investigate the beam dynamics in the presence of cooling (or self-interacting radiation field in general) and quantify the impact of various sources of error (e.g. transverse and phase jitter), guide data analysis.
* B. Andorf, V. A. Lebedev, J. Jarvis, and P. Piot Rev. Accel. Beams 21, 100702 (2018)

Poster WEPAB271 [1.649 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB271

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paper received ※ 16 May 2021 paper accepted ※ 06 July 2021 issue date ※ 13 August 2021

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WEPAB334

Development of Diffusion Bonded Joints of AA6061 Aluminum Alloy to AISI 316LN Stainless Steel for Sirius Planar Undulators

vacuum, interface, MMI, operation

3459

R.L. Parise, O.R. Bagnato, R. Defavari, M.W.A. Feitosa, F.R. Francisco, D.Y. Kakizaki, R.D. Ribeiro
LNLS, Campinas, Brazil

LNLS has been commissioning Sirius, a 4th-generation synchrotron light source. The commissioning of the beamlines has been mainly done by using planar undulator, which uses in-house built aluminum vacuum chambers with ultra-high vacuum tight bimetallic flanges. In order to manufacture these flanges, diffusion bonded joints of AA6061 aluminum alloy to AISI 316LN stainless steel were developed. Diffusion bonding was carried out at 400-500°C for 45-60 min, applying a load of 9.8MPa in a vacuum furnace. Also, the surface preparation for Al and SS was investigated. SEM observation revealed that an 1-3 µm reaction layer was formed at the AA6061/Ni-plated interface. The intermetallic compound Al3Ni was identified in the reaction layer. The obtained Al/SS joints showed mean ultimate strength of 84 MPa, with the fracture occurring in the Al/reaction layer interface. Bake-out cycles followed by leak tests were carried out to validate the process and approve their use on the planar undulator vacuum chambers. Two undulators with Al/SS flanges have been installed and are under operation in the storage ring.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB334

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paper received ※ 17 May 2021 paper accepted ※ 17 June 2021 issue date ※ 31 August 2021

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WEPAB335

Aluminum Vacuum Chamber for the Sirius DELTA 52 Undulator

vacuum, storage-ring, synchrotron, emittance

3463

T.M. Rocha, O.R. Bagnato, R.O. Ferraz, H.G. Filho, P.P.S. Freitas, G.R. Gomes, P.H. Lima, R.F. Oliveira, B.M. Ramos, F. Rodrigues, R.M. Seraphim, D.R. Silva, M.B. Silva
LNLS, Campinas, Brazil

Sirius is a 3 GeV fourth generation synchrotron light source under commissioning by the Brazilian Synchrotron Light Laboratory (LNLS). Delta Undulators with magnet vertical aperture of 13.6 mm, and period of 52.5 mm will be used for the generation of soft X rays to photoemission spectroscopy and X ray absorption experiments. Extruded aluminum vacuum chambers having small vertical aperture of 7.6 mm and horizontal aperture of 13 mm is proposed. This paper details the design and manufacturing processes of a complete chamber. Challenges regarding the TIG welding for aluminum and NEG coating for small aperture chambers will also be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB335

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paper received ※ 18 May 2021 paper accepted ※ 19 July 2021 issue date ※ 20 August 2021

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WEPAB336

Aluminum Vacuum Chamber for the Sirius Commissioning Undulators

vacuum, cathode, MMI, storage-ring

3467

B.M. Ramos, O.R. Bagnato, R.O. Ferraz, H.G. Filho, P.P.S. Freitas, G.R. Gomes, P.H. Lima, R.F. Oliveira, T.M. Rocha, F. Rodrigues, R.M. Seraphim, D.R. Silva, M.B. Silva
LNLS, Campinas, Brazil

Sirius is a 3 GeV fourth generation light source under commissioning by the Brazilian Synchrotron Light Laboratory (LNLS). Compact Linear Polarizing Undulators with magnet vertical aperture of 8 mm have been used for the commissioning of some beam lines. Extruded aluminum vacuum chambers having small vertical aperture of 6 mm and horizontal aperture of 40 mm, were built. This paper details the design and manufacturing processes of a complete chamber and its installation procedure at the storage ring. Challenges regarding the precision machining of the 0.5 mm wall thickness, TIG welding for aluminum, NEG coating for small apertures will also be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB336

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paper received ※ 18 May 2021 paper accepted ※ 25 August 2021 issue date ※ 20 August 2021

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THXB07

Coherent Radiation From Inverse Compton Scattering Sources by Means of Particle Trapping

electron, laser, radiation, FEL

3732

A. Fallahi, L. Novotny
ETH Zurich, Photonics Laboratory, Zurich, Switzerland
N. Kuster
ETH, Zurich, Switzerland

Funding: This work is supported by the Swiss National Science Foundation (SNSF) under the Spark grant CRSK-2-190840.
Inverse Compton scattering (ICS) sources are one of the promising compact tools to generate short wavelength radiation from electron beams based on the relativistic Doppler effect. Nonetheless, these sources suffer from a few shortcomings such as incoherent radiation and low-efficiency in radiation generation. This contribution presents a novel scheme based on the scattering of an optical beam from a trapped electron beam inside an optical cavity. Inverse-Compton scattering off both free and trapped electrons are simulated using a full-wave solution of first-principle equations based on FDTD/PIC in the co-moving frame of electron beams. It is shown that the strong space-charge effect in low-energies is the main obstacle in acquiring coherent gain through the ICS mechanism. Subsequently, it is shown that by trapping the electron beam to the high-intensity spots, the space-charge effect is compensated, and additionally, the ultrahigh charge density enables high FEL-gain at trapping spots, thereby augmenting the coherence of the output radiation and concurrently increasing the source efficiency by three orders of magnitude.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THXB07

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paper received ※ 28 May 2021 paper accepted ※ 01 July 2021 issue date ※ 24 August 2021

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THPAB035

Study of the Tolerances for Superconducting Undulators at the European XFEL

FEL, electron, simulation, photon

3819

B. Marchetti, S. Casalbuoni, V. Grattoni, S. Serkez
EuXFEL, Schenefeld, Germany

European XFEL is investing in the development of superconducting undulators (SCUs) for future upgrade of its beamlines SCUs made of NbTi, working at 2K, with a period length of 15 mm and a vacuum gap of 5 mm allow covering a range between 54 keV and 100 keV for 17.5 GeV electron energy. The effect of mechanical errors in the distribution of K along the undulators is more relevant for working points at lower photon energy, which are obtained using a higher magnetic field in the undulator. In this article we investigate the effect of error distribution in the K-parameter for a working point at 50keV photon energy obtained injecting an electron beam with 16.5 GeV energy from the XFEL linear accelerator in a undulator line composed by SCUs with 1.58 T peak magnetic field.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB035

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paper received ※ 12 May 2021 paper accepted ※ 05 July 2021 issue date ※ 18 August 2021

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THPAB036

Superconducting Phase Shifter Design for the Afterburner at the European XFEL

electron, FEL, photon, operation

3823

V. Grattoni, J.E. Baader, S. Casalbuoni
EuXFEL, Schenefeld, Germany

At the European XFEL, a superconducting afterburner is under design for the SASE2 hard X-ray beamline. It will consist of 5 undulator modules. One module corresponds to two superconducting undulator (SCU) coils of 2 m length plus one phase shifter. Such an afterburner will enable photon energies above 30 keV. Superconducting (SC) phase shifters will be installed in each undulator module to keep the correct phase delay between the electron beam and photon beam. In this contribution, we present the required SC phase shifter parameters to enable operation in the electron beam energy range 11.5-17.5 GeV. We also analyze different magnetic designs satisfying the calculated specifications.

Poster THPAB036 [0.991 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB036

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paper received ※ 18 May 2021 paper accepted ※ 06 July 2021 issue date ※ 12 August 2021

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THPAB037

Insertion Devices Impact on Solaris Storage Ring Optics

insertion, insertion-device, power-supply, storage-ring

3827

G.W. Kowalski, R. Panaś, A.I. Wawrzyniak
NSRC SOLARIS, Kraków, Poland

Solaris storage ring is currently operating with three insertion devices. The IDs installed are the APPLE II type elliptically polarised undulators (EPU). The UARPES beamline is operating with the long period length EPU of 120 mm (EPU120) which has a significant impact on the linear optics and tune shift. The linear optics compensation of the EPU120 impact is realised by local adjustment of SQFO quadrupole/sextupole focusing gradient and defocusing gradient in the flanking dipoles. Two additional EPUs with period lengths of 58 and 46.6 mm are recently installed for next beamlines PHELIX and DEMETER, respectively and are under commissioning now. To reduce the impact of all undulators movement the additional correction coils are installed and the correction feedforward tables has been determined experimentally. Additionally to keep the tune at the nominal values the tune feedback is planned to be implemented. Within this presentation the effect of all existing insertion devices on the linear optics based on measurements and simulations to be discussed. Moreover the nonlinear effects, especially the impact on dynamic aperture of Solaris storage ring will be investigated.

Poster THPAB037 [2.522 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB037

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paper received ※ 18 May 2021 paper accepted ※ 14 July 2021 issue date ※ 30 August 2021

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THPAB040

A Phase Shifter for Inline Undulators at the Advanced Photon Source Upgrade Project

photon, electron, permanent-magnet, radiation

3830

E.R. Moog, R.J. Dejus, A.T. Donnelly, Y. Piao, M.F. Qian, I. Vasserman, J.Z. Xu
ANL, Lemont, Illinois, USA

Funding: Work supported by U.S. Department of Energy, Office of Science, under contract number DE AC02-06CH11357.
Several undulator lines for the Advanced Photon Source Upgrade (APS-U) will consist of two inline undulators. In order to keep the undulators operating with optimal phasing over the full range of gaps, a phase shifter will be included between the undulators. A design has been developed for a phase shifter that will serve for a variety of undulator period lengths and gap ranges. The permanent-magnet phase shifter will use SmCo magnets to reduce the risk of radiation-induced demagnetization. The available space between the undulators is tight, so magnetic shields are placed between the undulators, the phase shifter, and the corrector magnet that is also located in the inter-undulator space. While these shields guard against magnetic cross-talk between the devices as the undulator and phase shifter gaps change, they do have an effect on the end fields of the devices. These end-field effects are examined and relevant tolerances are set and presented.

Poster THPAB040 [0.429 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB040

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paper received ※ 23 May 2021 paper accepted ※ 21 June 2021 issue date ※ 14 August 2021

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THPAB041

Design of Photon Masks for the ILC Positron Source

photon, positron, site, target

3834

K.S. Alharbi, G.A. Moortgat-Pick, A. Ushakov
University of Hamburg, Hamburg, Germany
K.S. Alharbi, S. Riemann
DESY Zeuthen, Zeuthen, Germany
K.S. Alharbi, A.O. Alrashdi
King Abdulaziz City for Science and Technology (KACST), The National Center for Accelerator Technology, Riyadh, Kingdom of Saudi Arabia
G.A. Moortgat-Pick
DESY, Hamburg, Germany
P. Sievers
CERN, Geneva, Switzerland

A long superconducting helical undulator is planned as baseline to produce polarized positrons at the International Linear Collider (ILC). To protect the undulator walls from synchrotron radiation, masks must be inserted along the undulator line. The power distribution deposited at these masks is studied in order to design the photon masks.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB041

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paper received ※ 19 May 2021 paper accepted ※ 07 July 2021 issue date ※ 12 August 2021

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THPAB042

Bending Radius Limits of Different Coated REBCO Conductor Tapes - An Experimental Investigation with Regard to HTS Undulators

experiment, collider, wiggler, positron

3837

S.C. Richter, A. Bernhard, A. Drechsler, A.-S. Müller, B. Ringsdorf, S.I. Schlachter
KIT, Karlsruhe, Germany
S.C. Richter, D. Schoerling
CERN, Geneva, Switzerland

Funding: This work has been sponsored by the Wolfgang Gentner Programme of the German Federal Ministry of Education and Research (grant no. 05E18CHA).
Compact FELs require short-period, high-field undulators in combination with compact accelerator structures to produce coherent light up to X-rays. Likewise, for the production of low emittance positron beams for future lepton colliders, like CLIC or FCC-ee, high-field damping wigglers are required. Applying high-temperature superconductors in form of coated REBCO tape conductors allows reaching higher magnetic fields and larger operating margins as compared to low-temperature superconductors like Nb-Ti or Nb₃Sn. However, short undulator periods like 13 mm may require bending radii of the conductor smaller than 5 mm inducing significant bending strain on the superconducting layer and may harm its conducting properties. In this paper, we present our designed bending rig and experimental results for REBCO tape conductors from various manufacturers and with different properties. Investigated bending radii reach from 20 mm down to 1 mm and optionally include half of a helical twist. To represent magnet winding procedures, the samples were bent at room temperature and then cooled down to T = 77 K in the bent state to test for potential degradation of the superconducting properties.

Poster THPAB042 [1.871 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB042

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paper received ※ 19 May 2021 paper accepted ※ 18 June 2021 issue date ※ 25 August 2021

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THPAB043

A Superconducting Undulator for CompactLight: Resistive Wall Wakefield Analysis

wakefield, impedance, electron, FEL

3841

K.B. Marinov
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

The CompactLight project is an advanced X-ray FEL light source, with high-frequency, high-gradient linacs and compact undulators. Lower electron energies give higher energy efficiency and a smaller environmental footprint. The extremely short bunch lengths (few fs) and narrow undulator gaps (4 mm) drastically increase the impact of resistive wall wakefields on the lasing process. The longitudinal resistive wall wakefield impedance is calculated in the framework of the surface impedance approach, in accordance with anomalous skin effect (ASE) theory. The dependence of the electron energy loss factor and the correlated energy spread of the bunch on the residual resistivity ratio (RRR) for both copper and aluminum is much higher for long (100 fs) than for ultra-short (6 fs) bunches. This is due to a known property of the longitudinal wakefield impedance - the field acting on a single particle traversing a resistive vessel does not depend on the conductivity of the vessel. The wakefields generated by the ultra-short bunch are already close to that of a single-particle regime and this leads to interesting consequences which are discussed in the present work.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB043

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paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 21 August 2021

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THPAB045

Design of a Short Period Helical Superconducting Undulator

FEL, electron, photon, simulation

3844

A.G. Hinton
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
J. Boehm, L. Cooper, B. Green, T. Hayler, P. Jeffery, C.P. Macwaters
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
S. Milward
DLS, Oxfordshire, United Kingdom
B.J.A. Shepherd
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
B.J.A. Shepherd
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Superconducting technology provides the possibility to develop short period, small bore undulators that can generate much larger magnetic fields than alternative technologies. This may allow an XFEL with optimised superconducting undulators to cover a broader range of wavelengths than traditional undulators. At STFC, we have undertaken work to design and build a prototype helical superconducting undulator (HSCU) module with parameters suitable for use on a future XFEL facility. This work includes the design of a full 2 m long undulator module, including an undulator with 13 mm period and 5 mm inner winding diameter, the supporting cryogenic and vacuum systems required for operation, and quadrupoles, phase shifters and correction magnets for use between undulator sections. We present here the magnetic and mechanical design of the HSCU. The choice of undulator parameters and their influence on the design is discussed. A turnaround scheme to allow continuous winding of the undulator without the need for superconducting joints is also presented. Techniques for winding the undulator are currently being investigated and a short prototype will soon be wound and tested.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB045

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paper received ※ 17 May 2021 paper accepted ※ 18 June 2021 issue date ※ 21 August 2021

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THPAB047

Status of Magnetic Measurement Benches for Insertion Device Characterization at MAX IV Laboratory

insertion, insertion-device, quadrupole, MMI

3848

M. Ebbeni, M. Gehlot, M. Holz, H. Tarawneh
MAX IV Laboratory, Lund University, Lund, Sweden

Insertion Devices (IDs) are the sole source of radiation used in all beamlines in MAX IV Laboratory with 14 IDs in operation of which 6 were built in-house. This paper shows the current capabilities and performance of the of the ID magnetic measurement systems, and the ongoing development work.

Poster THPAB047 [1.185 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB047

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paper received ※ 11 May 2021 paper accepted ※ 27 July 2021 issue date ※ 28 August 2021

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THPAB048

Design and Fabrication Concepts of a Compact Undulator with Laser-Structured 2G-HTS Tapes

laser, simulation, FEL, impedance

3851

A. Will, T.A. Arndt, E. Bründermann, N. Glamann, A.W. Grau, B. Krasch, A.-S. Müller, R. Nast, D. Saez de Jauregui
KIT, Karlsruhe, Germany
D. Astapovych, H. De Gersem, E. Gjonaj
TEMF, TU Darmstadt, Darmstadt, Germany

To produce small-scale high-field undulators for table-top free electron lasers (FELs), compact designs have been proposed using high temperature superconducting (HTS) tapes, which show both large critical current densities and high critical magnetic fields with a total tape thickness of about 50 μm and a width of up to 12 mm. Instead of winding coils, a meander structure can be laser-scribed directly into the superconductor layer, guiding the current path on a quasi-sinusoidal trajectory. Stacking pairs of such scribed tapes allows the generation of the desired sinusoidal magnetic fields above the tape plane, along the tape axis. Two practically feasible designs are presented, which are currently under construction at KIT: A coil concept wound from a single structured tape with a length of 15 m, which is a progression of a design that has been presented already in the past, as well as a novel stacked and soldered design, made from 25 cm long structured tapes, soldered in a zig-zag-pattern. In this contribution the designs are briefly recapped and the experimental progress is presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB048

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paper received ※ 19 May 2021 paper accepted ※ 12 July 2021 issue date ※ 15 August 2021

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THPAB049

Modeling the Magnetic Field of the LCLS-I Undulator for THz@PITZ

FEL, simulation, vacuum, experiment

3855

M. Krasilnikov, X. Li, A. Lueangaramwong, F. Mueller, F. Stephan
DESY Zeuthen, Zeuthen, Germany
A. Brachmann, H.-D. Nuhn
SLAC, Menlo Park, California, USA
M. Tischer, P. Vagin
DESY, Hamburg, Germany

Funding: This work was supported by the European XFEL research and development program
An accelerator-based THz source for pump-probe experiments at the European XFEL is under development at the Photo Injector Test Facility at DESY in Zeuthen (PITZ). For the proof-of-principle experiments an LCLS-I undulator is planned to be installed downstream of the PITZ accelerator. The fields of the undulator module 26 have been re-measured at DESY in Hamburg and the results are consistent with earlier SLAC measurements. A model for 3D field reconstruction based on the undulator magnetic measurements has been developed. It includes also a horizontal gradient of the vertical field. Tracking of the 17 MeV/c beam has revealed that the transverse gradient will lead to a significant off-axis trajectory in the horizontal plane. This offset has to be corrected with a steering coil, the design of which is also presented. The performance of the THz generation with the correction coil is discussed as well.

Poster THPAB049 [1.409 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB049

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paper received ※ 12 May 2021 paper accepted ※ 12 July 2021 issue date ※ 02 September 2021

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THPAB050

Compact Hybrid Planar Permanent Magnet Undulator Design for the APS Upgrade

ECR, lattice, photon, permanent-magnet

3859

M. Abliz, M. Borland, J.H. Grimmer, J.S. Kerby, M. Ramanathan, A. Xiao
ANL, Lemont, Illinois, USA

We report on the successful design of a compact 28-mm period hybrid planar permanent magnet (HPPM) undulator for the Advanced Photon Source Upgrade (APS-U) project. The design produces a peak field of 9750 G at a gap of 8.5 mm, with a pole width reduced to 35 mm as compared to the planar undulators currently in use at the Advanced Photon Source. The design includes a detailed investigation into the origin of the HPPM undulator demagnetization. We report on a finding of an optimization method that reduces the demagnetization field and increases the field at the gap center of the design. It includes an optimization of the pole edges to increase the field and decrease roll-off in the transverse direction. Further design optimizations include analyses of the mechanical assembly tolerances and comparison with the original design before building the device. Beam physics analyses included kick-map analysis, dynamic acceptance (DA), local momentum acceptance (LMA), and Touschek lifetime of this design were performed with the 42-pm lattice of the APS-U. Detailed magnetic design, effective field, field roll-off, magnetic force, and tracking results are reported.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB050

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paper received ※ 14 May 2021 paper accepted ※ 01 September 2021 issue date ※ 21 August 2021

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THPAB052

Insertion Devices at the MAX IV 3 GeV Ring

wiggler, photon, MMI, vacuum

3865

H. Tarawneh, M. Ebbeni, M. Gehlot, M. Holz
MAX IV Laboratory, Lund University, Lund, Sweden

Currently, there are 8 Insertion Devices (ID) installed and in operation and 2 new ones to be installed end of 2021 at the MAX IV 3 GeV storage ring. In this paper, the first commissioning results of the three newly installed IDs in 2020 will be described. The new IDs are one APPLE II for SoftiMAX beamline and two In-vacuum Undulators (IVU) for the DanMAX and CoSAXS beamlines. The mitigation scheme adopted to reduce undulator-like radiation from BALDER in-vacuum wiggler will be discussed. Two new IVUs with a period length of 17 mm and 18 mm for the ForMAX and MicroMAX beamlines will be installed during the winter shutdown of 2021-2022. Both IDs have 3 m lengths and a minimum gap of 4 mm. In this paper, the magnetic measurement results will be presented in terms of the achieved field quality and phase error.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB052

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paper received ※ 11 May 2021 paper accepted ※ 02 July 2021 issue date ※ 02 September 2021

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THPAB053

Magnetic Field Calculation of Planar SCUs Using ANSYS Maxwell

photon, FEL, software, software-tool

3868

Y. Shiroyanagi, E.A. Anliker, Q.B. Hasse, H. Hu, Y. Ivanyushenkov, M. Kasa, I. Kesgin
ANL, Lemont, Illinois, USA

Funding: This work was supported by U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
The Advanced Photon Source (APS) Upgrade includes a 4.8-m-long superconducting undulator (SCU) cryostat containing two 1.9-m-long, 16.5-mm-period planar NbTi undulator magnets. The magnetic and mechanical design of this magnet follows the design of the existing 1.1-m-long, 18-mm-period planar SCU that is currently in operation at the APS *. Although OPERA is a reliable standard software tool for magnetic field calculations, ANSYS Maxwell 3D has the advantage of calculating a large and complex geometry. In this paper, first, the magnetic field map, including the peak field and end fields, is bench-marked against the magnetic measurement data of the existing planar SCU18-1. Then, corrector current optimization is presented for the 1.5-m-long, 21-mm-period planar SCU. Finally, a magnetic field model of a full-scale, 1.9-m-long planar SCU is presented.
* Y. Ivanyushenkov et al., Phys. Rev. Accel. Beams 20, 100701 (2017).

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB053

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paper received ※ 18 May 2021 paper accepted ※ 18 June 2021 issue date ※ 11 August 2021

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THPAB054

Measurement Results of the First Scape Prototype

photon, insertion, superconducting-magnet, insertion-device

3872

M. Kasa, E.A. Anliker, Q.B. Hasse, Y. Ivanyushenkov, I. Kesgin, Y. Shiroyanagi, E. Trakhtenberg
ANL, Lemont, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
The SCAPE (SuperConducting Arbitrarily Polarizing Emitter) undulator is under development at the Advanced Photon Source (APS) as a part of the APS upgrade. SCAPE is comprised of four superconducting magnets which are arranged to create an on-axis undulator field that can be planar, elliptical, or circular. As a first step towards developing a full length device, a 0.5-meter long prototype was manufactured and assembled for testing in a liquid helium bath cryostat. A description of the mechanical assembly and subsequent measurement results of the first prototype will be presented in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB054

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paper received ※ 19 May 2021 paper accepted ※ 01 September 2021 issue date ※ 22 August 2021

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THPAB056

Conceptual Design of a Multiple Period Staggered Undulator

solenoid, radiation, electron, synchrotron

3879

I. Asparuhov, J. Chavanne, G. Le Bec
ESRF, Grenoble, France

In staggered undulators, a ferromagnetic pole structure paired to a solenoid generates a sinusoidal field. Interest of such insertion devices has been studied for application to FEL systems in the end of the previous century. However, the concept has never been used in synchrotron radiation sources due to the undesirable magnetic effect of the solenoid on electron beam parameters in storage rings. Advent of fourth-generation low emittance light sources is foreseen to change this situation. Indeed, consequent electron beam transverse size and divergence reduction for such new storage rings give promise for a beam less sensitive to the presence of a longitudinal solenoidal field. Relating to this, a staggered concept can be an adequate design choice for short-period undulators producing high-energy photon flux. Such undulators would have a low K value a priori limiting their photon energy tunability. Considering integration of separate magnetic arrays of distinct periods in a solenoid to compose a global assembly can help suppress this possible drawback. Magnetic design and radiative performance of such an insertion device are presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB056

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paper received ※ 19 May 2021 paper accepted ※ 12 July 2021 issue date ※ 02 September 2021

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THPAB057

Goubau-Line Set Up for Bench Testing Impedance of In-Vacuum Undulator Components

impedance, vacuum, wakefield, radiation

3883

P.I. Volz, S. Grimmer, M. Huck, A. Meseck
HZB, Berlin, Germany
A. Meseck
KPH, Mainz, Germany

The worldwide first in-vacuum elliptical undulator, IVUE32, is being developed at Helmholtz Zentrum Berlin. The 2.5 m long device with a period length of 3.2 cm and a minimum gap of about 7 mm is to be installed in the BESSY II storage ring. It will deliver soft X-radiation to several beamlines. The proximity of the undulator structure to the electron beam makes the device susceptible to wakefield effects which can influence beam stability. A complete understanding of its impedance characteristics is required prior to installation and operation, as unforeseen heating of components could have catastrophic consequences. Since its complex structure makes numerical calculations, such as CST simulations, at high frequency very resource intensive, bench testing the device may proof invaluable. A Goubau-line is a single wire transmission line for high frequency surface waves with a transverse electric field resembling that of a charged particle beam out to a certain radial distance. This can be used to measure the impedance of vacuum chamber components. A concept optimized for bench testing IVUE32-components will be discussed and progress towards the test bench set up will be shown.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB057

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paper received ※ 19 May 2021 paper accepted ※ 23 July 2021 issue date ※ 21 August 2021

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THPAB077

Magnetic Shims Studies for APS-U Hybrid Permanent Magnet Undulators

multipole, simulation, GUI, quadrupole

3941

Y. Piao, R.J. Dejus, M.F. Qian, I. Vasserman, J.Z. Xu
ANL, Lemont, Illinois, USA

Funding: Work supported by U.S. Department of Energy, Office of Science, under contract number DE-AC02-06CH11357
For the newly designed and fabricated APS Upgrade (APS-U) hybrid permanent magnet undulators (HPMUs), the development of magnetic shims has been critical to successfully tuning the undulators to meet the tight APS-U physics requirements. Different types of side and surface shims have been developed and applied for this purpose. The side shims are primarily used for trajectory tuning, and the surface shims are for phase and multipole tuning as well as trajectory tuning. Current design, applications, and measurement of the shims for the newly designed and fabricated APS28 (28 mm period) undulators are presented in this paper.

Poster THPAB077 [0.531 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB077

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paper received ※ 20 May 2021 paper accepted ※ 18 June 2021 issue date ※ 27 August 2021

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THPAB080

Correcting the Magnetic Field Offsets Inside the Undulators of the EuXFEL Using the K-Monochromator

FEL, radiation, electron, synchrotron

3953

F. Brinker
DESY, Hamburg, Germany
S. Casalbuoni, W. Freund
EuXFEL, Schenefeld, Germany

Hard X-ray free-electron lasers (XFELs) generate intense coherent X-ray beams by passing electrons through undulators, i.e. very long periodic magnet structures, which extend over hundreds of meters. A crucial condition for the lasing process is the spatial overlap of the electrons with the electromagnetic field. Well-established electron beam-based procedures allow finding a straight trajectory for the electrons defined by the beam position monitors (BPM) between the undulators. A bending of the trajectory in between the BPMs cannot be seen by these methods. A general field offset inside the undulators has the effect that the synchrotron radiation is emitted at a different angle at the beginning and the end of the undulator which can result in a degradation of the FEL-gain especially for very short wavelengths. We report on how the spectral and spatial characteristics of the monochromatized radiation of a single undulator can be used to minimize the field offset in situ with the help of correction coils.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB080

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paper received ※ 19 May 2021 paper accepted ※ 25 June 2021 issue date ※ 12 August 2021

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THPAB085

Status of Insertion Device Tuning for the APS Upgrade

storage-ring, photon, MMI, permanent-magnet

3966

R.J. Dejus, Y. Piao, M.F. Qian, J.M. TerHAAR, I. Vasserman, J.Z. Xu
ANL, Lemont, Illinois, USA

Funding: Work supported by U.S. Department of Energy, Office of Science, under contract number DE AC02-06CH11357.
The Advanced Photon Source Upgrade (APS-U) project is developing a multi-bend achromat (MBA) lattice at 6.0-GeV beam energy to replace the existing APS storage ring lattice operating at 7.0 GeV. One of the key components of the project is to design, fabricate, and install optimized insertion devices (IDs) for 35 beamlines. A plan was developed to standardize on four new undulator period lengths for 44 new undulators and to reuse 23 existing undulators with four more different period lengths. Early in the Upgrade project we anticipated there would be large challenges in meeting the tight fabrication and tuning schedules so that all undulators would be ready for installation in the upgraded storage ring prior to beam commissioning. With recent developments and techniques used in the magnetic measurement laboratory, we have successfully tuned many of the new and reused undulators to demanding magnetic field requirements. We will report on the tools and techniques used and on results to date.

Poster THPAB085 [0.890 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB085

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paper received ※ 19 May 2021 paper accepted ※ 21 June 2021 issue date ※ 15 August 2021

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THPAB126

Operational Experience and Characterization of a Superconducting Transverse Gradient Undulator for Compact Laser Wakefield Accelerator-Driven FEL

laser, electron, FEL, experiment

4009

K. Damminsek, A. Bernhard, J. Gethmann, A.W. Grau, A.-S. Müller, Y. Nie, M.S. Ning, S.C. Richter, R. Rossmanith
KIT, Karlsruhe, Germany

A 40-period superconducting transverse gradient undulator (TGU) has been designed and fabricated at Karlsruhe Institute of Technology (KIT). Combining a TGU with a Laser Wakefield Accelerator (LWFA) is a potential key for realizing an extremely compact Free Electron Laser (FEL) radiation source. The TGU scheme is a viable option to compensate the challenging properties of the LWFA electron beam in terms of beam divergence and energy spread. In this contribution, we report on the operational experience of this TGU inside its own cryostat and show the current status of the TGU and the further plan for experiments. This work is supported by the BMBF project 05K19VKA PlasmaFEL (Federal Ministry of Education and Research).

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB126

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paper received ※ 19 May 2021 paper accepted ※ 25 August 2021 issue date ※ 02 September 2021

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THPAB198

Commissioning of Current Strips for Elliptically Polarizing Undulators at NSLS-II

MMI, insertion, insertion-device, synchrotron

4160

Y. Hidaka, O.V. Chubar, T. Tanabe
BNL, Upton, New York, USA
C.A. Kitégi
SOLEIL, Gif-sur-Yvette, France

Funding: This work is supported by U.S. DOE under Contract No. DE-SC0012704.
Most of the Elliptically Polarizing Undulators (EPUs) at NSLS-II are equipped with current strips (or flat wires), attached to their vacuum chambers. These strips compensate the dynamic field integrals of the EPU to minimize undesirable nonlinear beam dynamics effect that can lead to reduction in injection efficiency and beam lifetime. For each EPU, we measured the field integrals of the insertion device alone, the current strips alone, and both, while creating horizontal bumps of different amplitudes at the straight section to assess the effectiveness of the compensation provided by the design current values for the strips. The commissioning results of these current strips are reported in this article.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB198

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paper received ※ 19 May 2021 paper accepted ※ 23 June 2021 issue date ※ 28 August 2021

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THPAB228

Study on Laser Modulator for Electron Beam Density Modulation

laser, electron, bunching, simulation

4241

K. Kan, M. Gohdo, J. Yang, Y. Yoshida
ISIR, Osaka, Japan

Ultrashort electron beams are essential for light sources and time-resolved measurements. Laser modulation using an undulator and pulsed near infrared light is expected for attosecond density modulation of electron beam. In this study, simulation of laser modulation using undulator with period length of 6.6 mm and optical pulse with a wavelength of 800 nm was performed by ELEGANT* code. Simulation results of laser modulation for electron beam with an energy of 32.5 MeV will be presented from a view point of the density modulation.
* M. Borland, elegant: A Flexible SDDS-Compliant Code for Accelerator Simulation, Advanced Photon Source LS-287, September 2000.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB228

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paper received ※ 19 May 2021 paper accepted ※ 28 July 2021 issue date ※ 16 August 2021

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THPAB249

X-Ray Beam Position Monitor (XBPM) Calibration at NSRC Solaris

controls, photon, insertion, radiation

4292

M. Waniczek, A. Curcio, G.W. Kowalski, R. Panaś, A.I. Wawrzyniak
NSRC SOLARIS, Kraków, Poland

During the installation of Front-ends in sections 4th (XMCD beamline frontend) and 6th (PHELIX beamline frontend) at National Synchrotron Radiation Centre Solaris (NSRC Solaris), two units (one for each front end) of X-ray Beam Position Monitors (XBPM) have been installed as a diagnostic tool enabling for measurement of photon beam position. Hardware units of XBPM were manufactured, delivered, and eventually installed in Solaris by FMB Berlin. In order to get readouts of beam position from XBPM units, Libera Photon 2016 controller has been used as a complementary electronic device. Since XBPM units are supposed to be used along with the insertion device, an on-site Libera calibration was necessary. Libera’s calibration required few iterations of scans involving gap and phase movement of insertion devices at the 4th and 6th sections of the Solaris ring. The main focus was put on the derivation of Kx, and Ky coefficients. The content of this document describes step by step the procedure of Libera’s Kx, Ky coefficients value derivation at NSRC Solaris.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB249

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paper received ※ 19 May 2021 paper accepted ※ 17 July 2021 issue date ※ 13 August 2021

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THPAB311

Using Linear Regression to Model the Parameters of the Flat Wires in TLS-EPU56

feedback, injection, hardware, electron

4399

S.J. Huang, Y.H. Chang, T.Y. Chung
NSRRC, Hsinchu, Taiwan
Y.W. Chen
Academia Sinica, Taipei, Taiwan

Although a theoretical calculation might predict the set currents of the flat wires, which are used to compensate the deviation in the Betatron tune caused by the elliptically polarized undulator (EPU), those set currents must still be tuned in reality. To approach this reality, a strategy of Machine Learning was adopted, which included collecting real-condition data and using a linear-regression model to adjust the parameters of the flat wires. After training the model, the predictions in variables tune x, tune y and beam size x were compared with the required amount of correction of the EPU at various gaps and phases. To prove the feasibility of this method, a test was performed under the real conditions of accelerator Taiwan Light Source (TLS).

Poster THPAB311 [1.226 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB311

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paper received ※ 13 May 2021 paper accepted ※ 28 June 2021 issue date ※ 30 August 2021

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