IPAC2017 - Classification: 02 Photon Sources and Electron Accelerators / T15 Undulators and Wigglers

Paper	Title	Page
TUOAA3	Progress of Pr2Fe14B Based Hybrid Cryogenic Undulators at SOLEIL	1213
SUSPSIK023	use link to see paper's listing under its alternate paper code
	A.M. Ghaith, P. Berteaud, F. Blache, F. Briquez, N. Béchu, M.-E. Couprie, J. Da Silva Castro, J.M. Dubuisson, C. Herbeaux, C.A. Kitegi, A. Lestrade, O. Marcouillé, F. Marteau, M. Sebdaoui, G. Sharma, A. Somogyi, K.T. Tavakoli, M. Tilmont, M. Valléau SOLEIL, Gif-sur-Yvette, France C. Benabderrahmane ESRF, Grenoble, France
	Cryogenic Permanent Magnet Undulators (CPMUs) take advantage of the enhanced field performance of permanent magnets when cooled down to low temperature, enabling shorter period with sufficient magnetic field to achieve high brightness radiation in the X-ray domain. Several CPMUs have been manufactured at SOLEIL. The first CPMU of period 18 mm (U18), optimized with a phase error of 3.2° at temperature of 77 K, has been installed and operated for the past 5 years at SOLEIL for the NANOSCOPIUM beamline. We report on photon beam based alignment enabling for a better adjustment of the vertical position offset of the undulator with a precision of 50 μm, and on the correction of the taper with a precision of 5 μrad to enhance the radiation flux. A second U18 cryo-ready undulator, with a new mechanical and magnetic sorting of module shimming, has attained a phase error of 2.3° at CT without any further adjustments after the assembly. Currently, two more CPMUs are being built; a 2 m long U18 for the SOLEIL ANATOMIX beamline, and a 3 m long U15 undulator reaching a magnetic gap of 3 mm. The new challenges encountered with magnetic measurements and mechanical designs for U15 are presented.
	Slides TUOAA3 [3.491 MB]
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TUPAB026	Status of the Cryogenic Undulator CPMU-17 for EMIL at BESSY II / HZB	1372
	J. Bahrdt, J. Bakos, W. Frentrup, S. Gottschlich, C. Kuhn, G. Pfeiffer, C. Rethfeldt, A. Rogosch-Opolka, M. Scheer, B. Schulz, L. Ziemann HZB, Berlin, Germany
	The CPMU-17 is the hard X-ray radiation source of a canted double undulator system for the Energy Materials In-situ Laboratory EMIL at BESSY II [1]. Various ambitious concepts are realized in this undulator such as Dy-hardened PrFeB-magnets, direct liquid Nitrogen cooling, dual loop feedback gap drive based on an optical micrometer and a low permeability stainless steel In-Vacuum(IV)-girder without keepers. The magnets are sorted according to Helmholtz coil and stretched wire data. Reproducibility and accuracy measurements of two IV-measurement tools needed for the CPMU-17 are presented: an IV-Hall probe bench and an IV-Moving Wire.
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TUPAB035	Field Quality of 1.5 m Long Conduction Cooled Superconducting Undulator Coils with 20 mm Period Length	1395
	S. Casalbuoni, N. Glamann, A.W. Grau, T. Holubek, D. Saez de Jauregui KIT, Eggenstein-Leopoldshafen, Germany C. Boffo, T.A. Gerhard, M. Turenne, W. Walter Babcock Noell GmbH, Wuerzburg, Germany
	The Institute for Beam Physics and Technology (IBPT) at the Karlsruhe Institute of Technology (KIT) and the industrial partner Babcock Noell GmbH (BNG) are col-laborating since 2007 on the development of superconducting undulators both for ANKA and low emittance light sources. The first full length device with 15 mm period length has been successfully tested in the ANKA storage ring for one year. The next superconducting undulator has 20 mm period length (SCU20) and is also planned to be installed in the accelerator test facility and synchrotron light source ANKA. The SCU20 1.5 m long coils have been characterized in a conduction cooled horizontal test facility developed at KIT IBPT. Here we present the local magnetic field and field integral measurements, as well as their analysis including the expected photon spectrum. S. Casalbuoni et al., Characterization and long term operation of a novel superconducting undulator with 15 mm period length in a synchrotron light source, Phys. Rev. ST Accel. Beams, vol. 19, p.110702, Nov. 2016.
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TUPAB036	Training and Characterization of 1.5m Long Conduction Cooled Superconducting Undulator Coils with 20 mm Period Length	1399
	A.W. Grau, S. Casalbuoni, N. Glamann, T. Holubek, D. Saez de Jauregui KIT, Eggenstein-Leopoldshafen, Germany C. Boffo, T.A. Gerhard, M. Turenne, W. Walter Babcock Noell GmbH, Wuerzburg, Germany
	The Institute for Beam Physics and Technology (IBPT) of the Karlsruhe Institute of Technology (KIT), and the company Babcock Noell GmbH (BNG) are running an R&D program on superconducting undulators (SCUs). The collaboration is working on a SCU with 20 mm period length (SCU20) for ANKA, the test facility and synchrotron radiation source, run by the IBPT. The 1.5 m long undulator coils have been tested in a conduction-cooled environment. This contribution describes the training, the stability and the thermal behavior of the coils.
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TUPAB041	Improvements in Production of Magnets and Pole Pieces for Undulators	1415
	F.-J. Börgermann Vacuumschmelze GmbH & Co. KG, Hanau, Germany
	Permanent magnets and highly saturable pole pieces are widely used in the setup of undulators as well as dipoles, quadrupoles and sextupoles. We will present actual improvements of precision, homogeneity and basic material properties in the range of NdFeB-based permanent magnets and CoFe-based soft magnetic alloys.
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TUPAB053	Proof-of-Principle Experiment of Phase-Combined Undulator	1446
	R. Kinjo, T. Tanaka RIKEN SPring-8 Center, Hyogo, Japan A. Kagamihata JASRI/SPring-8, Hyogo, Japan
	A huge attractive force is the largest concern in designing a mechanical structure of undulators, in which an accurate control and high uniformity of the gap between the upper and lower magnetic girders are required. This problem is especially serious for in-vacuum undulators, in which the girders are located inside the vacuum chamber. We have proposed a new concept called a phase-combined undulator, which has intrinsically no magnetic force. In this undulator, the magnetic forces acting on the girders locally head to the longitudinal axis instead of the attractive direction, and are actually canceled out in total. Numerical calculations have shown that the attractive force will be reduced down to a negligible level. Recently, we performed a proof-of-principle experiment to examine the feasibility of this undulator concept in terms of the force between the girders and magnetic field distribution, which will be reported in the conference. R. Kinjo and T. Tanaka, Phys. Rev. ST Accel. Beams 17, 122401
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TUPAB055	Development of compact magnetic field measurement system available for in-vacuum undulators	1449
	M. Adachi, R. Kato, T. Shioya, K. Tsuchiya KEK, Ibaraki, Japan
	A low-emittance 3-GeV KEK-LS* ring has been designed at KEK. KEK-LS's undulators can produce extremely high brightness light ranging from VUV to X-ray. Brightness of undulator light strongly depends on the phase error of its periodic magnetic field. Then a precise magnetic field adjustment is required in order to prevent the reduction of the brightness performance. Generally, the adjustment is performed by the conventional field measurement system equipped with hole-probes on a huge stone table. But, for the in-vacuum undulator, the measurement must be performed without the vacuum chamber. The additional phase error caused by reattaching the chamber is not negligible for the low emittance rings. Therefore, some groups have developed measurement systems available for the direct field measurement inside the chamber,. We have started to develop a compact measurement system. Our system is compacted and stabilized by utilizing the rigid metal beam of the undulator frame instead of the stone table. In the conference, we will report the detail of the system and the present status of the development. KEK-LS HP, http://kekls.kek.jp/ T. Tanaka, et al., Physical Review ST-AB, vol.12, p.120702 (2009). * M. Musardo, et al., Proceedings of IPAC2015, Richmond, VA, USA, p.1693 (2015).
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TUPAB064	Development of a PrFeB Cryogenic Permanent Magnet Undulator (CPMU) Prototype at IHEP	1469
	H.H. Lu, W. Chen, L. Gong, X.Y. Li, L.Z. Li, S.C. Sun, Y.J. Sun, Y.F. Yang, L. Zhang, X.Z. Zhang, S.T. Zhao IHEP, Beijing, People's Republic of China
	A PrFeB cryogenic permanent magnet undulator (CPMU) prototype is under construction for High Energy Photon Source Test Facility (HEPS-TF) at IHEP. The device is a full scale in-vacuum undulator with a magnetic length of 2 meters and a period of 13.5 mm, and it will work at less than 85K. The whole design scheme of prototype is presented and the specifications are given, where the consideration of in-vacuum magnetic measurement bench is also included. The development progress is introduced.
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TUPAB066	Mechanical Design of a Cryogenic Permanent Magnet Undulator at IHEP	1475
	S.C. Sun, W. Chen, L. Gong, X.Y. Li, L.Z. Li, H.H. Lu, Y.J. Sun, Y.F. Yang, L. Zhang, X.Z. Zhang, S.T. Zhao IHEP, Beijing, People's Republic of China
	High Energy Photon Source (HEPS) at Institute of High energy Physics (IHEP) is a new 6 GeV third generation electron storage ring. Insertion devices play a significant role in achieving the high performance of the photon source. A 13.5mm period-length Cryogenic Permanent Magnet Undulator (CPMU) prototype is designed and under construction. The mechanical structure designed based on physical requirements will be presented. Work supported by Project of High Energy Photon Source Test Facility, email address: sunsc@ihep.ac.cn
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TUPAB068	Design of the CPMU Vacuum System at the HEPS	1482
	L. Zhang, H.H. Lu, S.C. Sun IHEP, Beijing, People's Republic of China
	The High Energy Photon Source (HEPS) is a 3rd generation synchrotron radiation light source. Its beam energy is 6 GeV and its emittance is less than 60 pm'rad, which can provide high brilliance hard X-rays to several tens of experimental stations. The Cryogenic Permanent Magnet Undulator (CPMU) is one of the key components to achieve the high brilliance. And its vacuum system is necessary to provide an ultra-high vacuum environment for CPMU operation. To design the CPMU vacuum system, we do experiments to test the outgassing rate, estimate the total gas load, calculate the effective pumping speed, design the baking program and select all pumps and other vacuum equipments. This paper presents the design specifications and the assemblage status of the CPMU vacuum system.
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TUPAB071	Experimental Results on THz Superradiation From the Undulator in Tsinghua University Beamline	1488
SUSPSIK024	use link to see paper's listing under its alternate paper code
	X.L. Su, Y.-C. Du, W.-H. Huang, L. Niu, C.-X. Tang, Q.L. Tian, D. Wang, L.X. Yan TUB, Beijing, People's Republic of China Y.F. Liang Tsinghua University, Beijing, People's Republic of China
	In this paper, the first operation of a widely tunable 8-period undulator at terahertz (THz) frequency in Tsinghua University beamline was reported. Superradiate undulator radiation from sub-picosecond electron bunches compressed by chicane was observed. The measured radiation curve shows clearly that the radiation energy is proportional to the charge square, and the THz frequency can be changed from 0.4 THz to 10 THz with narrow-band spectrums. Our results demonstrate a high power and tunable coherent THz source, which could be useful for many applications in the future.
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TUPAB087	Undulator Commissioning Experience at PAL-XFEL	1520
	D.E. Kim, Y.G. Jung, H.-S. Kang, I.S. Ko, H.-G. Lee, S.B. Lee, W.W. Lee, K.-H. Park, H.S. Suh PAL, Pohang, Kyungbuk, Republic of Korea I.S. Ko POSTECH, Pohang, Kyungbuk, Republic of Korea J. Pflüger XFEL. EU, Hamburg, Germany
	Pohang Accelerator Laboratory (PAL) is developing a 0.1 nm SASE based FEL based on 10 GeV S-band linear accelerator named PAL-XFEL. The hard X-ray undulator line requires 20 units of 5 m long hybrid-type conventional planar undulator while soft X-ray line requires 7 units of 5 m long hybrid type planar undulators. In this report, the final measurement results of all the undulators, phase matching scheme, and the commissioning experiences will be summarized.
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TUPAB104	Optimized Undulator to Generate Low Energy Photons From Medium to High Energy Accelerators	1556
	T.Y. Chung, M.-S. Chiu, J.C. Huang, C.-S. Hwang, J.C. Jan, C.K. Yang NSRRC, Hsinchu, Taiwan H.W. Luo NTHU, Hsinchu, Taiwan
	While emitting low energy photons from a medium or high energy storage ring, the on-axis heat load on the beam line optics can become a critical issue. In addition, the heat load in the bending magnet chamber, especially in the vertical and circular polarization mode of operation may cause some concern. In this work, we compare the heat loads for the APPLE-II and the Knot-APPLE, both optimized to emit 10 eV photons from the 3 GeV TPS. Under this constraint the heat load analysis, synchrotron radiation performance and features in various polarization modes are presented. Additional consideration is given to beam dynamics effect.
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TUPAB105	Field Measurement System for a Cryogenic Permanent Magnet Undulator in TPS	1559
	C.K. Yang, C.H. Chang, T.Y. Chung, W.H. Hsieh, J.C. Huang, C.-S. Hwang NSRRC, Hsinchu, Taiwan
	Short period in-vacuum, permanent magnet undulators operating at cryogenic temperatures are being developed worldwide to serve as brilliant and coherent light sources for medium energy storage rings. A hybrid cryogenic permanent magnet undulator (CU) with PrFeB magnets has now been designed and constructed at NSRRC [1]. To characterize the performance and to determine magnetic field errors after cool down poses some technical chal-lenges compared to room temperature undulators. A new system combining a Hall probe and a stretched wire has been designed to measure the field integrals, trajectory, phase errors, and K value under low temperature and vacuum conditions. Field measurements in this cryogenic undulator will be performed around 77 K as well as at room temperature, making temperature dependent calibra-tion of the Hall probes necessary. The main features and improvement of the measurement and calibration system are presented.
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TUPAB106	Development of a Cryogenic Permanent Magnet Undulator for the TPS	1562
	J.C. Huang, C.H. Chang, T.Y. Chung, C.-S. Hwang, J.C. Jan, C.S. Yang, C.K. Yang NSRRC, Hsinchu, Taiwan H. Kitamura RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
	Development of a cryogenic permanent magnet undu-lator (CPMU) at the Taiwan Photon Source (TPS) is the most recent activity toward a new light source for the Phase-II beamlines. A hybrid-type CPMU with a period length of 15 mm is under construction with PrFeB permanent-magnet materials. A maximum effective magnetic field of 1.77 T at a gap of 3 mm is expected when the magnets (PMs) are cooled down around 77 K. The features desired for the TPS CPMU are low-intrinsic-phase-error characteristics and high thermal budget for various kinds of heat loads. The design of the TPS CPMU is discussed in this paper.
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TUPAB114	Design Study for a Plasma Undulator Experiment Using Capillary Based Discharge Plasma Source	1584
	O. Mete Apsimon, R. Apsimon, Y. Ma, D. Seipt, M.J.V. Streeter, A.G.R. Thomas Cockcroft Institute, Lancaster University, Lancaster, United Kingdom T.H. Pacey, G.X. Xia UMAN, Manchester, United Kingdom
	A plasma undulator is formed when a short laser pulse is injected into plasma off-axis or at an angle that causes the centroid of this laser pulse to oscillate. Ponderomotively driven plasma wake will follow this centroid given that the product of the plasma wave number and the characteristic Rayleigh length of the laser is much larger than one. This oscillating transverse wakefield may work as an undulator forcing particles to follow sinusoidal trajectories and emit synchrotron radiation. In this paper, plans for an experiment are introduced and resulting radiation and injected beam characteristics are discussed. The aforementioned laser centroid oscillations are demonstrated using, EPOCH, a PIC code for laser-plasma interactions.
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TUPAB115	Impact of Electron Beam Heating on Insertion Devices at Diamond Light Source	1588
	E.C.M. Rial, Z. Patel DLS, Oxfordshire, United Kingdom
	Electron beam heating is a widely observed phenomenon at synchrotron facilities around the world, and has a large impact particularly on cryogenic insertion devices, but also on room temperature devices. This paper seeks to outline electron beam heating measurements taken at Diamond Light Source (DLS) and produces an empirical heat load relationship that matches the form of heating through the anomalous skin effect, although gives an order of magnitude higher than that predicted by theory. Resistive wall heating should vary inversely with the gap of installed cryogenic and permanent magnet insertion devices. This is also examined in this paper and the results presented.
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TUPAB116	Insertion Devices at Diamond Light Source: A Retrospective Plus Future Developments	1592
	Z. Patel, A. George, S. Milward, E.C.M. Rial, A.J. Rose, R.P. Walker, J.H. Williams DLS, Oxfordshire, United Kingdom
	2017 marks the tenth year of Diamond operation, during which time all insertion device straights have been filled. Diamond Light Source is a third generation, 3 GeV facility that boasts 29 installed insertion devices. Most room temperature devices have been designed, manufactured and measured in-house, and progress has been made in structure design and control systems to ensure new devices continue to meet stringent requirements placed upon them. The ‘completion' of the storage ring is not, however, the end of activity for the ID group at Diamond, as beamlines map out potential upgrade paths to Cryogenic Permanent Magnet Undulators (CPMUs) and SuperConducting Undulators (SCUs). This paper traces the progress of ID design at Diamond, and maps out future projects such as the upgrade to CPMUs and the challenges of designing a fixed-gap mini-wiggler to replace a sextupole in the main storage ring lattice.
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TUPAB117	Conceptual Design of a Novel SCAPE Undulator	1596
	Y. Ivanyushenkov, J.F. Fuerst, E. Gluskin, Q.B. Hasse, M. Kasa, Y. Shiroyanagi, E. Trakhtenberg ANL, Argonne, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357. A concept of a novel SuperConducting Arbitrarily Polarizing Emitter, or SCAPE, has recently been suggested at the Advanced Photon Source. It consists of two pairs - both vertical and horizontal - of superconducting planar magnets assembled around a beam vacuum chamber. Such a device will be capable of generating either planar or circularly polarized photons, depending on which pair of magnets is energized. The magnetic simulation suggests that due to the employment of superconducting technology, the expected magnetic field is higher than that of the APPLE undulators. The SCAPE undulators could be useful for the fourth generation of storage rings with a multi-bend achromat lattice, as well as for the FELs where utilization of round beam vacuum chambers becomes possible. The results of magnetic modelling, as well as the design concept of the SCAPE, are presented.
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TUPAB122	Engineering Optimization of The Support Structure and Drive System for the LCLS-II Soft X-Ray Undulator Segments	1602
	A.J. DeMello, D. Arbelaez, D. Bianculli, A.P. Brown, J.N. Corlett, J.R. Dougherty, D.E. Humphries, J.-Y. Jung, M. Leitner, S. Marks, K.A. McCombs, K.L. Ray, D.A. Sadlier, D. Schlueter, E.J. Wallén LBNL, Berkeley, California, USA
	Funding: Work supported by the Director, O'ce of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. The Linear Coherent Light Source II (LCLS-II) project, an upgrade to the free-electron laser facility at SLAC, is replacing the undulator system from a fixed gap to a variable gap system to enable tuning of the photon energy range. The LCLS-II project will include a soft x-ray (SXR) beam line and a hard x-ray (HXR) beam line. The SXR undulators are conventional vertical-gap horizontally-polarizing devices while the HXR undulators are novel horizontal-gap vertically-polarizing devices. This paper describes in detail the development of the SXR mechanical support structure and drive system. The effort has included extensive analysis of the various components to ensure that the undulators will perform within the design specifications. Engineering simulations undertaken and experiments performed to validate the computer modeling are presented together with measurement results from prototype and pre-production undulators.
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TUPAB123	Hard X-Ray and Soft X-Ray Undulator Segments for the Linear Coherent Light Source Upgrade (LCLS-II) Project	1605
	M. Leitner, D. Arbelaez, A.J. Band, D. Bianculli, A.P. Brown, J.N. Corlett, A.J. DeMello, J.R. Dougherty, L. Garcia Fajardo, K. Hanzel, M. Hoyt, D.E. Humphries, D. Jacobs, C. Joiner, J.-Y. Jung, D. Leitner, S. Marks, K.A. McCombs, D.V. Munson, K.L. Ray, D.A. Sadlier, J.J. Savino, D. Schlueter, E.J. Wallén, V. Waring, A. Zikmund LBNL, Berkeley, California, USA C.J. Andrews, D.E. Bruch, A.L. Callen, G. Janša, S. Jansson, K.R. Lauer, Yu.I. Levashov, D.S. Martinez-Galarce, B.D. McKee, H.-D. Nuhn, Ž. Oven, M. Rowen, Z.R. Wolf SLAC, Menlo Park, California, USA
	Funding: Work supported by the Director Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Stanford Linear Accelerator Laboratory is currently constructing the Linear Coherent Light Source II (LCLS-II), a free-electron laser (FEL) which will deliver x-rays at an energy range between 0.2 keV and 5 keV at high repetition rate of up to ~1 MHz using a new 4 GeV superconducting RF linac, and at and an energy range between 1 keV and 25 keV when driven by an existing copper linac at up to 120 Hz repetition rate. To cover the full photon energy range, LCLS-II includes two variable-gap, hybrid-permanent-magnet undulator lines: A soft x-ray undulator (SXR) line with 21 undulator segments optimized for a photon energy range from 0.2 keV to 1.3 keV plus a hard x-ray undulator (HXR) line with 32 undulator segments designed for a photon energy range from 1.0 keV to 25.0 keV. Lawrence Berkeley National Laboratory is responsible for fabricating the 53 undulator segments. This paper summarizes the main parameters and design attributes for both LCLS-II undulator segment types.
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TUPAB124	Development of the Manufacturing and QA Processes for the Magnetic Modules of the LCLS-II Soft X-Ray Undulators	1609
	K.L. Ray, D. Arbelaez, A.J. Band, D. Bianculli, A.P. Brown, J.N. Corlett, A.J. DeMello, J.R. Dougherty, L. Garcia Fajardo, K. Hanzel, D.E. Humphries, J.-Y. Jung, D. Leitner, M. Leitner, S. Marks, K.A. McCombs, D.V. Munson, D.A. Sadlier, D. Schlueter, E.J. Wallén, V. Waring, A. Zikmund LBNL, Berkeley, California, USA D.E. Bruch, A.L. Callen, G. Janša, D.S. Martinez-Galarce, H.-D. Nuhn, E. Ortiz, Ž. Oven, M. Rowen, Z.R. Wolf SLAC, Menlo Park, California, USA
	Funding: Work supported by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. A new free electron laser being built at SLAC National Accelerator Laboratory, the Linear Coherent Light Source II (LCLS-II), will use 21 soft x-ray undulators (SXR) and 32 hard x-ray undulators (HGVPU). Lawrence Berkeley National Laboratory (LBNL) is responsible for the design and manufacturing of all variable-gap, hybrid permanent-magnet undulators. The physics requirements for the undulators specify a longitudinal pole misalignment maximum rms error of 25 μm and a vertical pole misalignment maximum error of 50 μm. In addition, magnet positioning critically influences the gap-dependent field properties due to saturation effects at the smallest operational gaps. This paper discusses the manufacturing and QA methods developed to carefully control the longitudinal and vertical pole and magnet positions during undulator production. Inspection results are discussed based on data gathered during construction of a prototype as well as pre-production soft x-ray undulator.
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TUPAB125	Magnetic Field Measurements at LBNL on Soft X-Ray and Hard X-Ray Undulator Segments for the Linear Coherent Light Source Upgrade (LCLS-II) Project	1612
	E.J. Wallén, D. Arbelaez, J.N. Corlett, L. Fajrado, H.W. Kim, M. Leitner, S. Marks, D. Schlueter, A. Zikmund LBNL, Berkeley, California, USA Yu.I. Levashov, H.-D. Nuhn, Z.R. Wolf SLAC, Menlo Park, California, USA
	Funding: Work supported by the Director, O'ce of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Stanford Linear Accelerator Laboratory is currently constructing the Linear Coherent Light Source II (LCLS-II), a FEL which will deliver x-rays at an energy range 0.2-5 keV at high repetition rate of up to 1 MHz using a new 4 GeV superconducting linac, and at an energy range 1-25 keV when using the existing copper linac at up to 120 Hz. To cover the full photon energy range, LCLS-II includes two variable-gap, hybrid-type permanent magnet undulator lines: A soft x-ray undulator (SXR) line with 21 undulator segments for the photon energy range 0.2-1.3 keV plus a hard x-ray undulator (HXR) line with 32 undulator segments designed for a photon energy range from 1-5 keV when using the superconducting linac. The HXR line is also designed to support 25 keV and higher photon energies when using the existing copper linac. Lawrence Berkeley National Laboratory (LBNL) is responsible for fabricating the undulators and tuning 23 of the HXR undulators. This paper summarizes the magnetic field measurements carried out on the pre-production undulators and describes the plans at LBNL for the magnetic measurements on the HXR undulators in series production.
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TUPAB134	Life Expectancy Studies for LCLS-II Permanent Magnet Undulators	1640
	M. Santana-Leitner, D.E. Bruch, R.C. Field, D.S. Martinez-Galarce, B.D. McKee, H.-D. Nuhn, M. Rowen, S.W. Score SLAC, Menlo Park, California, USA
	Funding: Work supported by U.S. Department of Energy contract DE-AC02-76SF00515 LCLSII at SLAC National Accelerator Laboratory will add a 4 GeV superconducting Linac to the existing 20 GeV Cu structure. Electron beams from the two sources going through two new variable gap undulators [] will produce FEL ranging 200-5000 keV at up to 929 kHz, also reaching 20 keV at low frequency. Such performance will be achieved by hybrid design undulators with NdFeB magnet blocks until radiation-induced demagnetization exceeds 0.01%. This is a sizable challenge, as LCLS-II will carry 120 kW beams in both its soft (SXR) and hard (HXR) beam-lines. Even small fractional losses could result excessive if too frequent or not detected and aborted fast enough. A model of SXR undulator was set for FLUKA [] radiation transport, including segments, phase-shifters, quadrupoles, RFBPM, stands/pillars and interconnecting parts. Components were installed according to MAD files, which were also used to code the optics. Beam-loss/shower propagation was simulated for beam mis-steering, interception at wire scanners and gas-bremsstrahlung interactions. Results help set limits on shut-off times, uniform loss levels and wire scanner use, and to define placement for beam loss monitors. M. Leitner et al, Hard X-Ray and Soft X-Ray Undulator Segments for the Linear Coherent Light Source Upgrade (LCLS-II) Project, these proceedings ** A. Ferrari et al, The FLUKA Code: Developments and Challenges for High Energy and Medical Applications, Nuclear Data Sheets 120, 211-214 (2014)
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TUPAB135	A 1.75 mm Period RF-Driven Undulator	1643
	F. Toufexis, S.G. Tantawi SLAC, Menlo Park, California, USA
	Funding: This project was funded by U.S. Department of Energy under Contract No. DE-AC02-76SF00515, and the National Science Foundation under Contract No. PHY-1415437. To reduce the linac energy, and hence the size required for a Free Electron Laser radiating at a given wavelength, a smaller undulator period with sufficient field strength is needed. Previous work from our group successfully demonstrated a microwave undulator at 11.424 GHz using a corrugated cylindrical waveguide operating in the HE11 mode. Scaling down the undulator period using this technology poses the challenge of confining and coupling* the electromagnetic fields while maintaining over-moded features for power handling capability and electron beam wakefield mitigation. In this work, we present a novel end section of an RF undulator at 91.392 GHz. To confine the fields inside the undulator, a corrugated waveguide is connected through a matching section to a linear taper and a mirror. After the mirror, a Bragg reflector and a matching section are used to reflect back all the fields leaking out of the mirror opening. * F. Toufexis, J. Neilson, and S.G. Tantawi, Coupling and Polarization Control in a mm-wave Undulator, these proceedings.
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TUPAB136	Coupling and Polarization Control in a mm-wave Undulator	1647
	F. Toufexis, J. Neilson, S.G. Tantawi SLAC, Menlo Park, California, USA
	Funding: This project was funded by U.S. Department of Energy under Contract No. DE-AC02-76SF00515, and the National Science Foundation under Contract No. PHY-1415437. To reduce the linac energy required for an FEL radiating at a given wavelength, and hence its size, a smaller undulator period with sufficient field strength is needed. Previous work from our group successfully demonstrated a microwave undulator at 11.424 GHz using a corrugated cylindrical waveguide operating in the HE11 mode. Scaling down the undulator period using this technology poses the challenge of confining and coupling the electromagnetic fields while maintaining overmoded features for power handling capability and electron beam wakefield mitigation. We have designed a mm-wave undulator cavity at 91.392 GHz. This undulator requires approximately 1.4 MW for sub-microsecond pulses to generate an equivalent K value of 0.1. Transferring such amounts of power in mm-wave frequencies requires overmoded corrugated waveguides, and coupling through irises creates excessive pulsed heating. We have designed a novel mode launcher that allows coupling power from a highly overmoded corrugated waveguide to the undulator through the beam pipe. Additionally, this mode launcher can be used along with grating polarizers to control the polarization of the produced light. F. Toufexis and S.G. Tantawi, A 1.75 mm Period RF-Driven Undulator, these proceedings.
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TUPAB140	Analysis and Correction of in-Vacuum Undulator Misalignment Effects in a Storage Ring Synchrotron Radiation Source	1663
	O.V. Chubar, T.A. Caswell, Y. Chen-Wiegart, A. Fluerasu, Y. Hidaka, D.A. Hidas, C.A. Kitegi, M.S. Rakitin, T. Tanabe, J. Thieme, L. Wiegart, G. Williams BNL, Upton, Long Island, New York, USA
	Funding: Work was partially supported by US DOE SBIR grants DE-SC0006284 and DE-SC0011237. In-vacuum undulators (IVU) are currently very extensively used at different light source facilities, and in particular in medium-energy storage rings, for the production of high-brightness and high-flux hard X-rays. The relatively small (~5 mm or less) vertical magnetic gaps used in these planar undulators make them, however, rather sensitive to the accuracy of alignment of magnet arrays with respect to electron orbit in the vertical plane. Based on results of commissioning of a number of IVUs at hard X-ray beamlines of NSLS-II, their eventual misalignment with respect to the electron orbit was found to be among frequent reasons of spectral underperformance of the beamlines. We will present results of simulations of different IVU misalignment effects on magnetic fields seen by electron beam and on the emitted undulator radiation spectra. The simulations show e.g. that an impact of angular misalignment of an IVU on the radiation spectrum can be minimized if the IVU elevation is selected to make the electron orbit to pass through the IVU magnetic center. Experimental results of spectrum-based alignment of IVUs at hard X-ray beamlines will be presented.
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TUPAB146	Vibration Measurements of Super-Conducting Undulator at SSRF	1675
	R.B. Deng, Y. Liu, L. Wang, S. Xiang SINAP, Shanghai, People's Republic of China
	Funding: Work supported by the National Natural Science Foundation of China (Grant No. 11405255) A Super-Conducting Undulator (SCU) is being built at SSRF. Mechanical stability of SCU is critical to beam stability since the central load is supported by special strings in SCU and the vibration of load will cause directly the vibration of beam. In this paper, vibration results of several key components including central load, cold head, frame support, etc, are studied under different working mode of compressors. The ground vibrations at different distances are compared to get the influence of compressors to SCU. Useful suggestions and possible measures are described to mitigate the vibration and improve SCU stability.
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TUPIK106	Analysis of the Synchrotron Radiation from Segmented Undulator in Double-Mini Beta Function	1964
SUSPSIK025	use link to see paper's listing under its alternate paper code
	H.W. Luo, C.H. Lee NTHU, Hsinchu, Taiwan T.Y. Chung, C.-S. Hwang NSRRC, Hsinchu, Taiwan C.-S. Hwang NCTU, Hsinchu, Taiwan
	Three long straight sections with double-mini beta-y lattice were created in the Taiwan Photon Source (TPS) for which the effects of focusing elements and phase shifters between the collinear undulators result in incorrect calculations of the brilliance while assuming a Gaussian-approximation. Therefore, an on-axis Wigner distribution function (WDF), which includes effects of wave phenomena, is a natural way to measure the intensity of synchrotron radiation and is used in this article as the definition of brilliance.
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WEOCA3	Status of the Development of Superconducting Undulators at the Advanced Photon Source	2499
	Y. Ivanyushenkov, C.L. Doose, J.F. Fuerst, E. Gluskin, Q.B. Hasse, M. Kasa, Y. Shiroyanagi ANL, Argonne, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357 Superconducting planar undulator (SCU) technology has been developed and is currently in use at the Advanced Photon Source (APS). The experience of building and operating the first short-length, 16-mm period superconducting undulator, SCU0, paved the way for two 1-m long, 18-mm period devices, SCU18-1 and SCU18-2. The first of those undulators has been in operation since May 2015, while the second one replaced SCU0 in September 2016. The possibility of building planar SCUs with a high quality field has been demonstrated at the APS. The measured phase errors of SCU18-2 at the design operational current are only 2 degrees rms, for example. An FEL SCU prototype - a 1.5-m long, 21-mm period undulator - was also built and tested as part of an LCLS SCU R&D program. This undulator successfully achieved all LCLS-II undulator requirements including a phase error of 5 degrees rms. The superconducting undulator technology also allows the fabrication of circular polarizing devices. Currently, a new helical SCU is under construction at the APS. In addition, the concept of a novel Superconducting Arbitrarily Polarizing Emitter, or SCAPE, has been suggested and is now under development.
	Slides WEOCA3 [2.826 MB]
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Paper

Title

Page

TUOAA3

Progress of Pr2Fe14B Based Hybrid Cryogenic Undulators at SOLEIL

1213

SUSPSIK023

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

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

Slides TUOAA3 [3.491 MB]

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TUPAB026

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

1372

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

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

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TUPAB035

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

1395

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

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

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TUPAB036

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

1399

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

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

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TUPAB041

Improvements in Production of Magnets and Pole Pieces for Undulators

1415

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

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

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TUPAB053

Proof-of-Principle Experiment of Phase-Combined Undulator

1446

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

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

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TUPAB055

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

1449

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

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

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TUPAB064

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

1469

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

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

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TUPAB066

Mechanical Design of a Cryogenic Permanent Magnet Undulator at IHEP

1475

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

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

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TUPAB068

Design of the CPMU Vacuum System at the HEPS

1482

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

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

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TUPAB071

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

1488

SUSPSIK024

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

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

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TUPAB087

Undulator Commissioning Experience at PAL-XFEL

1520

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

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

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TUPAB104

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

1556

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

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

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TUPAB105

Field Measurement System for a Cryogenic Permanent Magnet Undulator in TPS

1559

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

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

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TUPAB106

Development of a Cryogenic Permanent Magnet Undulator for the TPS

1562

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

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

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TUPAB114

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

1584

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

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

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TUPAB115

Impact of Electron Beam Heating on Insertion Devices at Diamond Light Source

1588

E.C.M. Rial, Z. Patel
DLS, Oxfordshire, United Kingdom

Electron beam heating is a widely observed phenomenon at synchrotron facilities around the world, and has a large impact particularly on cryogenic insertion devices, but also on room temperature devices. This paper seeks to outline electron beam heating measurements taken at Diamond Light Source (DLS) and produces an empirical heat load relationship that matches the form of heating through the anomalous skin effect, although gives an order of magnitude higher than that predicted by theory. Resistive wall heating should vary inversely with the gap of installed cryogenic and permanent magnet insertion devices. This is also examined in this paper and the results presented.

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TUPAB116

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

1592

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

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

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TUPAB117

Conceptual Design of a Novel SCAPE Undulator

1596

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

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

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TUPAB122

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

1602

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

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

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TUPAB123

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

1605

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

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

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TUPAB124

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

1609

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

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

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TUPAB125

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

1612

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

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

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TUPAB134

Life Expectancy Studies for LCLS-II Permanent Magnet Undulators

1640

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

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

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TUPAB135

A 1.75 mm Period RF-Driven Undulator

1643

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

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

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TUPAB136

Coupling and Polarization Control in a mm-wave Undulator

1647

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

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

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TUPAB140

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

1663

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

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

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TUPAB146

Vibration Measurements of Super-Conducting Undulator at SSRF

1675

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

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

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TUPIK106

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

1964

SUSPSIK025

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

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

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

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WEOCA3

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

2499

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

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

Slides WEOCA3 [2.826 MB]

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