02 Photon Sources and Electron Accelerators
T15 Undulators and Wigglers
Paper Title Page
TUPMF007 Cryogenic Testing and Initial Performance of a Helical Superconducting Undulator at the APS 1260
 
  • J.D. Fuerst, E. Gluskin, Q.B. Hasse, Y. Ivanyushenkov, M. Kasa, I. Kesgin, 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.
A helical superconducting undulator (HSCU) has been installed and is presently operational at the Advanced Photon Source (APS) at Argonne National Laboratory (ANL). We describe the final assembly and cryogenic test program which led to successful operation, representing the culmination of a two-year development effort. Details of the cryostat and cryogenic system design are presented along with as-installed performance data and a comparison with design expectations.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF007  
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TUPMF008 Design, Construction, and Magnetic Field Measurements of a Helical Superconducting Undulator for the Advanced Photon Source 1263
 
  • M. Kasa, S.J. Bettenhausen, J.D. Fuerst, E. Gluskin, Q.B. Hasse, Y. Ivanyushenkov, I. Kesgin, 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 helical superconducting undulator (HSCU) was developed and installed at the Advanced Photon Source (APS). Implementation of a unique design of the helical coil former allowed for a compact turn around scheme of the conductor at the ends of the device during winding. Inherent to the coil winding design was the gradual reduction of the magnitude of the magnetic field at the ends of the device. The coil former design along with the magnetic measurement results will be described.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF008  
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TUPMF021 Investigation of Options for Damping Trapped IVU Resonances 1296
 
  • R.T. Dowd
    AS - ANSTO, Clayton, Australia
  • W.J. Chi, D. Pelz
    RFS, Kilsyth, Australia
 
  Trapped resonances have been observed within the three In-Vacuum Undulators (IVUs) insertion devices at the Australian Synchrotron. These resonances can create vertical beam instability if not controlled through transverse feedback systems. Similar resonances have been observed at other synchrotron light sources around the world. Under certain conditions of undulator gap, these resonances can couple quite strongly to the beam, requiring high feedback gain. An investigation of the resonances has been carried out using 3D eigenmode and wakefield simulations to understand the resonances and determine the effectiveness of various schemes for modifying the damping the resonances.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF021  
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TUPMF040 Alignment of Current Strips at the Canadian Light Source 1342
 
  • W.A. Wurtz
    CLS, Saskatoon, Saskatchewan, Canada
  • Q.L. Zhang
    SINAP, Shanghai, People's Republic of China
 
  The Quantum Materials Spectroscopy Centre beamline at the Canadian Light Source will employ a 180 mm period elliptically polarizing undulator (EPU180), which will have significant impacts on beam dynamics with large tune shifts and reductions in dynamic aperture. Current strips mounted to the vacuum chamber are intended to mitigate the effects of EPU180 with each strip powered by an independent power supply. It is important to accurately model the current strips in order to calculate the required compensation. We model the current strips as straight wires, parallel to the electron beam, with small horizontal and vertical displacements from their nominal positions. As the real current strips are not completely straight, this is an effective model, but justified as we are mostly interested in the magnetic field integrated along the strips. By activating two strips and measuring the ratio of the two currents needed to minimize closed orbit distortion in the horizontal and vertical planes, we can find the effective horizontal and vertical displacements of the straight wires in the model. Our goal is to create an effective model of the strips from beam-based measurements.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF040  
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TUPMF045 Performance Optimization of a Prototype Undulator U38 Using Multi-Objective Genetic Algorithm 1353
 
  • L.G. Yan, D.R. Deng, P. Li, D. Wu
    CAEP/IAE, Mianyang, Sichuan, People's Republic of China
 
  Funding: The project of the national large-scale instrument development: 2011YQ130018; National Natural Science Foundation of China: 11505174, 11505173 and 11605190.
Genetic Algorithm (GA) is one of the most excellent method to search the optimal solution of a problem, which has been applied to solve various problems. It is hard to estimate shim applied on raw undulator precisely. There are many methods have been developed to solve the problem. In this proceeding, we measured the magnetic field distribution of prototype undulator U38 and concluded the shim using multi-objective GA. The code was written with the language of Python and based on the package pyevolve. A multi-objective fitness function was setup to implement the multi-objective optimization. Experimentally,performances satisfied the requirements by shimming U38 three times. The trajectory center deviation, peak-to-peak error and phase error are reduced to 0.15 mm, 0.49% and 1°.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF045  
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TUPMK003 Advances in the Sirius Delta-Type Undulator Project 1491
SUSPF031   use link to see paper's listing under its alternate paper code  
 
  • L.N.P. Vilela, R. Basílio, J.F. Citadini, J.R. Furaer, F. Rodrigues
    LNLS, Campinas, Brazil
 
  The Delta undulator is a compact adjustable-phase insertion device that provides full light polarization control. Five undulators of this type will be installed in the initial operation phase of Sirius, the new 4th generation synchrotron light source that is being built by the Brazilian Synchrotron Light Laboratory (LNLS). In this work we present the recent advances in the development of Sirius Delta-type undulator, the studies of the effects of this device in the storage ring beam dynamics and assembly and measurements strategies.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMK003  
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WEXGBD1 Development of Very Short Period Undulators 1735
 
  • S. Yamamoto
    KEK, Ibaraki, Japan
 
  Scientists and engineers at KEK have developed undulator magnets having very short period lengths. Magnet plates 100mm and 152mm long with 4-mm period length have been successfully fabricated. They produce an undulator field of approximately 4kG at a gap of 1.6mm. The magnetic field characterization shows that the undulator field is satisfactory in quality for a very short period undulator. KEK has recently installed a short-period undulator at a 50-MeV linac and observed a first light, and will soon start an experiment using a short-period undulator with laser-accelerated electrons for future table-top XFELs. This invited talk summarizes the current status, and experimental activities and results related to short-period undulators and table-top FELs.  
slides icon Slides WEXGBD1 [3.520 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEXGBD1  
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WEYGBD2 Status of the Radiation Damage on the European XFEL Undulator Systems 1776
 
  • F. Wolff-Fabris, J. Pflüger
    XFEL. EU, Schenefeld, Germany
  • F. Hellberg
    Stockholm University, Stockholm, Sweden
  • F. Schmidt-Föhre
    DESY, Hamburg, Germany
 
  The European XFEL GmbH is a new X-ray FEL user facility and started lasing in 2017. Three gap movable SASE Undulator Systems are designed to produce FELs with tunable wavelengths from 0.05 to 5.2nm [*,**]. A total of 91 5-m long undulator segments based on hybrid NdFeB permanent magnet technology were tuned respecting tight specifications. Radiation damage due to machine operation affects the magnetic properties of the segments and the quality of the SASE process. An array of dosimeters based on Radfets [***] and Gafchromic films monitors the absorbed doses in every undulator segment and each SASE system is equipped with a 12mm gap diagnostic undulator (DU) which is magnetically re-measured during machine maintenance weeks. Doses up to 4 kGy have been observed and magnetic field degradation higher than 3% is measured. These results permit to estimate the effects of radiation damage and life expectancy of the Undulator Systems based on the precise K-parameter determination for beam operation. We will present the results of magnetic re-measurements on the Undulator Systems, the details of the effects of radiation damage and future plans to maximize the beam quality and operation.
* M. Altarelli et al., Tech. Design Rep. DESY 2006-097, July 2007.
** E. Schneidmiller et al., Eur. XFEL Tech. Rep. TR-2011-006, Sep. 2011.
*** F. Schmidt-Föhre et al., IPAC-2018 contribution.
 
slides icon Slides WEYGBD2 [3.675 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEYGBD2  
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THPMF022 Study of Possible Beam Losses After Post-Linac Collimation at European XFEL 4092
 
  • S. Liu, W. Decking
    DESY, Hamburg, Germany
  • F. Wolff-Fabris
    XFEL. EU, Schenefeld, Germany
 
  The European XFEL has been operating with the undulator beam line SASE1 and SASE3 since April 2017 and February 2018, respectively. Despite of the fact that the post-linac collimation has collimated the beam halo to ~20 σ level*, relative high radiation doses have been measured especially in the diagnostic undulator (DU) section**. In order to find the sources of beam losses after post-linac collimation, BDSIM simulations have been performed. In this paper, we will first present the possible losses generated by the wire scanners upstream of the undulators during a scan. The simulation results will be compared with the measured doses along SASE1 and SASE3 undulators. Based on the simulation results, we will estimate the frequency for wire scanner opera-tions. Besides, the simulations with large extension of beam halo hitting the vacuum chamber aperture transition will also be presented. Finally, other possible radiation dose sources will be discussed.
* S. Liu et al., in Proc. of FEL 2017, Santa-Fe, USA, Aug. 2017, paper TUP003.
** F. Wolff-Fabris et al.,IPAC-2018 contribution.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF022  
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THPMF066 Performance of a Full Scale Superconducting Undulator with 20 mm Period Length at the KIT Synchrotron 4223
 
  • S. Casalbuoni, S. Bauer, E. Blomley, N. Glamann, A.W. Grau, T. Holubek, E. Huttel, D. Saez de Jauregui
    KIT, Eggenstein-Leopoldshafen, Germany
  • C. Boffo, T.A. Gerhard, M. Turenne, W. Walter
    Bilfinger Noell GmbH, Wuerzburg, Germany
 
  Within the collaborative effort between KIT and Bilfinger Noell GmbH the development of a full scale superconducting undulator with 20 mm period length (SCU20) has been completed. This device addresses the reliability and reproducibility aspects of the manufacturing process, allowing for the status of a commercial product. The conduction cooled 1.5 m long coils were characterized in the KIT horizontal test facility CASPER II and later assembled in the final cryostat. The system was extensively tested in the final configuration before installation in the KIT storage ring KARA (Karlsruhe Research Accelerator) to be the source of the NANO beamline in December 2017. Here we present the performance of the device.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF066  
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THPMF067 Design and Tests of Switchable Period Length Superconducting Undulator Coils 4226
 
  • T. Holubek, S. Casalbuoni, S. Gerstl, N. Glamann, A.W. Grau, C.A.J. Meuter, D. Saez de Jauregui
    KIT, Eggenstein-Leopoldshafen, Germany
 
  Several photon beamlines in different synchrotron make use of undulators with switchable period length, which offer a larger tunability of the emitted photons energy. Superconducting technology allows switching the period length by changing the sign of the current in separately powered subset of windings. We present here the design and tests performed in liquid helium of switchable period length superconducting undulator coils performing period doubling from 17 mm to 34 mm.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF067  
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THPMK012 Reduction of Dynamic Multipole Content in Insertion Devices Using Flat Wires 4313
 
  • T.Y. Chung, S.D. Chen, M.-S. Chiu, S.J. Huang, C.-S. Hwang, J.C. Jan, C.Y. Kuo, Y.T. Li, C.Y. Wu
    NSRRC, Hsinchu, Taiwan
  • C.-S. Hwang
    NCTU, Hsinchu, Taiwan
 
  Multipole errors of an insertion device are generally corrected based on measurements and analysis of the magnetic field integrals. Multipole components in a strong and narrow non-uniform field of an insertion device appear as dynamic multipoles. Flat wires were installed and commissioned to determine if the dynamic multipoles can be eliminated in an APPLE-II type undulator. In this work, we will discuss and compare the reduction of the dynamic multipole content and it's beam dynamics effects with the flat wire through an analysis of field calculations and beam-based measurements in the storage ring.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK012  
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THPMK013 A Wiggler Magnet Design for the TPS 4317
 
  • J.C. Jan, Y.L. Chu, C.-S. Hwang, F.H. Tseng
    NSRRC, Hsinchu, Taiwan
 
  The Taiwan Photon Source (TPS) at the National Synchrotron Radiation Research Center (NSRRC) is an advanced photon source facility operating at an electron energy of 3 GeV. Ten insertion devices (IDs) have been installed in phase-I during 2015. Recently, plans and designs for several phase-II IDs including In-vacuum Undulators (IU), Cryogenic Undulators (CU), Elliptical Polarization Undulators (EPU) and Wiggler magnets are pursued at NSRRC. These IDs are expected to be installed before 2020. In particular, a room temperature wiggler magnet with 100 mm period length (W100), will be designed and installed for phase-II. The field strength of the W100 is 1.8 T and the number of main periods is four. It is designed to generate 5-50 keV photons for the microscopy beam line. The magnetic design and photon characteristics of the W100 together with its effects on the stored beam will be discussed in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK013  
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THPMK014 Quantitative Analysis of Multipole Errors Induced by Mechanical Deformations of an Undulator 4321
 
  • T.Y. Chung, C.H. Chang, C.-S. Hwang
    NSRRC, Hsinchu, Taiwan
  • H.W. Luo
    NTHU, Hsinchu, Taiwan
 
  To minimize unwanted beam dynamics effects in a storage ring, multipole errors in an undulator are normally reduced by sorting and shimming methods. Nonetheless, an investigation of the error source is worth pursuing and interesting. Our work focuses on multipole errors introduced by mechanical deformations of an APPLE-II type undulator, which undergoes complicated forces during operation. Our results give guidelines for mechanical specifications derived from quantitative analyses.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK014  
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THPMK028 Inverse Free Electron Laser Separatrix Crossing for Energy Gain and Stability 4354
SUSPF030   use link to see paper's listing under its alternate paper code  
 
  • N.S. Sudar, P. Musumeci
    UCLA, Los Angeles, USA
  • D. Garzella
    CEA, Gif-sur-Yvette, France
 
  The laser wakefield accelerator (LWFA) has been proposed as a driver for next generation compact light sources. However, the beams produced by LWFA's typically exhibit correlated energy spread and energy jitter too large to drive the Free Electron Laser instability. We present here a novel scheme whereby using a highly non-linear strongly tapered undulator interaction directly after the LWFA we are able to trap and accelerate a large fraction of charge in the moving Inverse Free Electron Laser ponderomotive bucket. The final correlated energy spread and output energy are determined by the final bucket height and central energy of the ponderomotive bucket which are both determined by the stagnant undulator parameters, resulting in a significant decrease in the normalized energy spread (< 1%) and output energy jitter (< 1%). This interaction is treated both analytically and numerically.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK028  
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THPMK031 Elliptically Polarizing Undulator Design for PAL-XFEL 4362
 
  • S.J. Lee, J.H. Han, D.E. Kim
    PAL, Pohang, Kyungbuk, Republic of Korea
 
  Funding: This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT (2017R1C1B1012852).
Elliptically polarizing undulator (EPU) is under consideration as after-burner for the PAL-XFEL soft X-ray beamline to control the FEL polarization. In the soft X-ray line, seven planar undulators with a 35 mm period and 5 m length are in operation. To provide a polarization control of the FEL in the 1 to 3 nm wavelength, we compare the two types of EPUs, APPLE-II, and APPLE-X. The K value ranges for various operation modes are numerically studied for two undulator periods, 35 and 40 mm, of these EPU types.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK031  
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THPMK032 RADFET Installation at PAL-XFEL Undulator 4366
 
  • J.H. Han, Y.G. Jung, D.E. Kim, S.J. Lee, G. Mun
    PAL, Pohang, Kyungbuk, Republic of Korea
 
  Two undulator beamlines, one hard X-ray and one soft X-ray, are in operation at PAL-XFEL. Radiation produced during the FEL operation may impair the magnetic property of the undulator magnets and affect the FEL performance. Accumulated radiation at the undulator sections is being measured by using optically stimulated luminescent dosimeters (OSLDs) once per few months. Over 10 Gy gamma ray was detected at some locations at both undulator beamlines. However, in the measurement using the OSLDs we do not have information on which accelerator operation modes produce such high level of radiation on the undulators. To measure accumulated radiation in real time, we installed radiation-sensing field-effect transistors (RADFETs). We report the characteristics of the RADFET sensors and the installation at the PAL-XFEL undulator beamlines.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK032  
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THPMK066 Cryogenic Permanent Magnet Undulator of SSRF 4449
 
  • Y.Z. He, M.F. Qian, H.F. Wang, W. Zhang, Q.G. Zhou
    SINAP, Shanghai, People's Republic of China
 
  Funding: Work supported by the State Key Lab of Advanced Metals and Materials (2016-Z03) and the Youth Innovation Promotion Association of CAS (Grant No: 2017305)
The two Cryogenic Permanent Magnet Undulators (CPMU18 with PrFeB magnets P46H and CPMU20 with NdFeB magnets N48H) were designed and developed in SSRF in the past few years (2014-2017).This paper introduces magnetic performance of the permanent magnets, design parameters of the two CPMUs, cryogenic cooling and magnetic field of the two CPMUs and so on. When gap of the two CPMUs is about 6.0 mm, the measurement results showed that the effective magnetic field peak of CPMU18 at 300 K and 77 K was 0.82 T, 0.92T, respectively, and the magnetic field phase error is about 3 degrees and 5 degrees respectively. The effective magnetic field peak of CPMU20 at 300 K and 140 K was 0.94T and 1.03T, respectively, and the magnetic field phase error was 3 degrees and 3.5 degrees respectively.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK066  
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THPMK073 Multi FEL Lines with Compact Undulator Layout 4470
 
  • D. Wang
    SINAP, Shanghai, People's Republic of China
 
  Today the high repetition rate X-ray Free Electron Lasers based on superconducting radiofrequency technologies have come to their age. Such kind of facilities are able to serve many FEL photon beamlines simultaneously with each of which have large flexibilities in selecting wavelength, intensity, polarization, coherence and other properties through independent tuning of the undulator magnets. In reality the space needed to accommodate many undulator lines could be a limiting factor of user capacity, especially for the high rep rate XFELs that tend to utilize the underground tunnel to host long superconducting accelerator machines. In this paper we present a concept of compact undulator layout for more FEL lines in the precious tunnel spaces or similar environment. Shanghai Coherent Light Facility(SCLF) is a high repe-tition rate X-ray Free Electron Lasers installed in under-ground tunnels with an overall length of more than 3 km. The concept described in this paper could be applied to the SCLF or similar FEL facilities. The design and R&D progress will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK073  
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