D - Key Technologies
Paper Title Page
MOA2PL03 Review of New Developments in Superconducting Undulator Technology at the APS 1
 
  • 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.
Superconducting undulator (SCU) technology offers the possibility of enhancing the magnetic field of undulators compared to other undulator technologies. It also allows for the fabrication of circular polarizing devices in addition to the planar undulators. Work on SCUs therefore continues in the light source community. Recent developments in SCU technology will be presented.
 
slides icon Slides MOA2PL03 [1.669 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-MOA2PL03  
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TUP1WD01
Comparative Study of RF BPM Performance via Beam Measurements at NSLS-II  
 
  • D. Padrazo Jr, T.V. Shaftan
    BNL, Upton, Long Island, New York, USA
 
  NSLS-II developed and built RF BPM receivers that have been used in the past three years during commissioning of 200 MeV linac, 3 GeV booster and storage ring and now are in routine operations. Recently we completed an upgrade of BPM DFE Digital Front End gaining benefits of a Xilinx Zynq FPGA. This FPGA includes a hard dual-core ARM A9 processor which will permit more advanced signal processing routines, faster ethernet communication, as well as resources to implement a pilot tone based active calibration, eliminating the need of thermal controlled racks. In the past year we procured a Libera Brilliance Plus BPM electronics unit to benchmark the outcome of our upgrade with respect to one of the best commercially available solutions. This presentation is focused on comparison of performance between NSLS-II RF BRM version 2 with the Libera unit focusing on the following performance parameters: Long term stability for 10Hz, as well as characterization of FA, TBT and ADC Raw data set. We conclude our presentation by outlining future directions in upgrading NSLS-II RF BPM AFE, DFE and high-level controls to enable breakthrough in the area of diagnostics of charged particle beams.  
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TUP1WD02 A Study on the Improved Cavity Bunch Length Monitor for FEL 39
 
  • Q. Wang, X.Y. Liu, P. Lu, Q. Luo, B.G. Sun, L.L. Tang, J.H. Wei, F.F. Wu, Y.L. Yang, T.Y. Zhou, Z.R. Zhou
    USTC/NSRL, Hefei, Anhui, People's Republic of China
 
  Funding: Supported by The National Key Research and Development Program of China (2016YFA0401900), NSFC (11375178, 11575181) and the Fundamental Research Funds for the Central Universities (WK2310000046)
Bunch length monitors based on cavities have great potential especially for future high quality beam sources because of many advantages such as simple structure, wide application rage, and high signal-to-noise ratio (SNR). The traditional way to measure bunch length needs two cavities at least. One is reference cavity, whose function is to get the beam intensity. The other one is defined as main cavity, which is used to calculate the bunch length. There are some drawbacks. To improve performance, the mode and the cavity shape are changed. At the same time, the position and orientation of coaxial probe are designed to avoid interference modes which come from the cavity and beam tube according to the analytic formula of the electromagnetic field distribution. A series simulation based on CST is performed to verify the feasibility, and the simulation results reveal that the improved monitor shows good performance in bunch length measurement.
 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-TUP1WD02  
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TUP1WD03 The Development and Applications of the Digital BPM Signal Processor at SINAP 43
 
  • L.W. Lai, S.S. Cao, F.Z. Chen, Y.B. Leng, Y.B. Yan, W.M. Zhou
    SSRF, Shanghai, People's Republic of China
  • J. Chen, Y.B. Leng, Y.B. Yan, W.M. Zhou
    SINAP, Shanghai, People's Republic of China
 
  BPM signal processor is one of key beam diagnostics instruments. It has been progressing from analog to digital. The current major processors are digital BPM signal processor (DBPM). Except for some commercial products on-the-shelf, several laboratories developed in-house DBPMs for their own facilities. SINAP started the DBPM development since 2009, when the SSRF phase-I has been completed. After years of optimization, the DBPM has been used in large-scale on some facilities, including SSRF, DCLS and SXFEL. At the same time, some extended functions have been developed to meet special applications on accelerator based on the hardware platform. This topic will introduce the development and applications of the DBPM at SINAP, also the future DBPM development for next generation light source will be discussed here.  
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TUP2WD01
Next Generation X-Ray Beam Position Monitor Development for the Advanced Photon Source Upgrade  
 
  • B.X. Yang
    ANL, Argonne, Illinois, USA
 
  Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
Current undulator XBPMs in the Advanced Photon Source (APS) can handle limited beam power and have strong bend magnet background. The next generation XBPM will separate the power-handling elements from the signal detectors using x-ray fluorescence from aperture components and x-ray scattering from low-Z blades. They showed distinct design advantages: (1) The water-cooled aperture components greatly enhance power-handling capacity, up to the APS-U 20-kW undulators. (2) Additional x-ray optics, such as pinhole-camera, enables center-of-mass, gap-independent measurements. (3) Proper beam-intercepting elements tailor the XBPM spectral properties and suppress the background, improving undulator measurement accuracy. (4) Using limiting apertures as the XBPM allows aiming the undulator beam reliably at the aperture during user operations, eliminating the common alignment issue between the aperture and the XBPM. In this report, we discuss the x-ray physics, mechanical design, computer simulation and beam measurements of these x-ray beam position monitors for the APS Upgrade. Possible applications to the free electron laser will be discussed.
 
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TUP2WD02
Emittance Measurements on Future Ring Light Sources  
 
  • Å. Andersson
    MAX IV Laboratory, Lund University, Lund, Sweden
 
  The MAX IV 3 GeV ring is designed to produce a bare lattice horizontal electron beam emittance of 330 pm·rad. We present different methods using visible or near visible SR, for measuring this so far unsurpassed low horizontal emittance. In this way we can minimize systematic errors, and we also point out those measurement methods that could best serve emittance determinations on future, below 100 pm·rad, emittance light sources.  
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TUP2WD03 Turn-by-Turn Measurements for Systematic Investigations of the Micro-Bunching Instability 46
 
  • J.L. Steinmann, M. Brosi, E. Bründermann, M. Caselle, S. Funkner, B. Kehrer, A.-S. Müller, M.J. Nasse, G. Niehues, L. Rota, M. Schuh, P. Schönfeldt, M. Siegel, M. Weber
    KIT, Karlsruhe, Germany
 
  Funding: Funded by the German Federal Ministry of Education and Research (Grant No. 05K16VKA) & Initiative and Networking Fund of the Helmholtz Association (contract number: VH-NG-320).
While recent diffraction-limited storage rings provide bunches with transverse dimensions smaller than the wavelength of the observed synchrotron radiation, the bunch compression in the longitudinal plane is still challenging. The benefit would be single cycle pulses of coherent radiation with many orders of magnitude higher intensity. However, the self-interaction of a short electron bunch with its emitted coherent radiation can lead to micro-bunching instabilities. This effect limits the bunch compression in storage rings currently to the picosecond range. In that range, the bunches emit coherent THz radiation corresponding to their bunch length. In this paper, new measurement setups developed at the Karlsruhe Institute of Technology are described for systematic turn-by-turn investigations of the micro-bunching instability. They lead to a better understanding thereof and enable appropriate observation methods in future efforts of controlling and mastering the instability. Furthermore, the described setups might also be used as high repetition rate bunch compression monitors for bunches of picosecond length and below.
 
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TUP2WD04 Preliminary Design of HEPS Storge Ring Vacuum Chambers and Components 52
 
  • P. He, B. Deng, D.Z. Guo, Q. Li, B.Q. Liu, Y. Ma, Y.C. Yang, L. Zhang
    IHEP, Beijing, People's Republic of China
  • X.J. Wang
    Institute of High Energy Physics (IHEP), People's Republic of China
 
  In the design process of HEPS vacuum system, we meet the following limitations. Vacuum chamber must fit inside multipole magnet bore diameter of 25mm (without touching). Water channels and x-ray extraction ports must pass through a 11mm vertical pole gap. Provide an average pressure of 1nTorr during operations with 200mA beam current. Control thermal drift of BPM to ~μm and vibration amplitude ~nm level. Minimize impedance effects. This paper introduces the design of various vacuum chambers, including material selection, mechanical simulation analysis, welding test and so on.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-TUP2WD04  
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WEA1PL03 Attosecond Timing 79
 
  • F.X. Kärtner
    Deutsches Elektronen Synchrotron (DESY) and Center for Free Electron Science (CFEL), Hamburg, Germany
  • K. Shafak
    CFEL, Hamburg, Germany
  • K. Shafak
    Cycle GmbH, Hamburg, Germany
  • M. Xin
    DESY, Hamburg, Germany
 
  Funding: This work was supported by DESY and the European Research Council under the European Union's Seventh Framework Program (FP/2007-2013) / ERC Grant Agreement No. 609920.
Photon-science facilities such as X-ray free-electron lasers (XFELs) and intense-laser facilities are emerging world-wide with some of them producing sub-fs X-ray pulses. These facilities are in need of a high-precision timing distribution system, which can synchronize various microwave and optical sub-sources across multi-km distances with attosecond precision. Here, we report on a synchronous laser-microwave network that permits attosecond precision across km-scale distances. This was achieved by developing new ultrafast timing metrology devices and carefully balancing the fiber nonlinearities and fundamental noise contributions in the system. New polarization-noise-suppressed balanced optical crosscorrelators and free-space-coupled balanced optical-microwave phase detectors for improved noise performance have been implemented. Residual second- and third-order dispersion in the fiber links are carefully compensated with additional dispersion-compensating fiber to suppress link-induced Gordon-Haus jitter and to minimize output pulse duration; the link power is stabilized to minimize the nonlinearity-induced jitter as well as to maximize the signal to noise ratio for locking.
 
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WEA2WD01 QUAPEVA: Variable High Gradient Permanent Magnet Quadrupole 89
 
  • C.A. Kitegi, T. André, M.-E. Couprie, A. Ghaith, J. Idam, A. Loulergue, F. Marteau, D. Oumbarek, M. Sebdaoui, M. Valléau, J. Vétéran
    SOLEIL, Gif-sur-Yvette, France
  • C. Benabderrahmane, J. Chavanne, G. Le Bec
    ESRF, Grenoble, France
  • O. Cosson, F. Forest, P. Jivkov, J.L. Lancelot
    Sigmaphi, Vannes, France
  • P. N'gotta
    MAX IV Laboratory, Lund University, Lund, Sweden
  • C. Vallerand
    LAL, Orsay, France
 
  We present the magnetic and the mechanical design of tunable high gradient permanent magnet (PM) quadrupoles. The tunable gradient of the so-called QUAPEVAS extends from 100T/m up to 200T/m. Seven of them with various lengths, ranging from 26mm up to 100mm, for different integrated quadrupole strengths were manufactured. The measured magnetic performance of these devices is also reported. These devices were successfully developed to transport laser plasma accelerated electron beam. Such applications have however less stringent multipole harmonic content constraints than diffraction limited Light sources. Trails for lowering the multipole harmonics will be discussed.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-WEA2WD01  
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WEA2WD02
Design Study of the High Gradient Magnets for a Future Diffraction-Limited Light Source at MAX IV  
 
  • A.S. Vorozhtsov, P.F. Tavares
    MAX IV Laboratory, Lund University, Lund, Sweden
 
  The introduction of the multibend achromat lattice has ushered in a new era for storage-ring based light sources allowing order-of-magnitude improvements in source performance. A central ingredient in various engineering implementations of the MBA concept is the use of high gradient magnets with significantly smaller apertures than in previous generations of storage rings. Another increasingly common theme is the large scale use of permanent magnet technology. This paper describes the design study of 11 mm bore diameter high gradient magnets in frame of the upgrade concept for a future diffraction-limited light sources reaching the diffraction limit at X-ray wavelengths, i.e. providing emittances on the order of 10 pm·rad within the constraints of the existing MAX IV 3 GeV ring tunnel (528 m circumference). Preliminary lattice designs with 19 bends per achromat have been used as the starting point for the magnet design study. Two solutions such as conventional electromagnet and a hybrid magnet (combination of permanent magnet and electromagnet) are compared. The possible technical challenges that shall be overcome to realize this project are discussed.  
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WEA2WD03 Analysis of Electron Trajectories in Harmonic Undulator with SCILAB's Model Based Design Codes 93
 
  • H. Jeevakhan, S. Kumar
    NITTTR, Bhopal, India
  • G. Mishra
    Devi Ahilya University, Indore, India
 
  Scilab's X-cos model-based simulation blocks has been used to simulate the trajectories of an electron traversing through an Harmonic undulator. The trajectory of electron along X and Y directions has been simulated from Numerical and analytical methods. Analysis given in the present paper is compared with the other codes. Parallel simulation of Harmonic undulator magnetic field along with trajectories of electron is given in the present analysis.  
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WEA2WD04 Harmonic Undulator Radiation with Dual Non Periodic Magnetic Components 98
 
  • H. Jeevakhan
    NITTTR, Bhopal, India
  • G. Mishra
    Devi Ahilya University, Indore, India
 
  Undulator radiation at third harmonics generated by harmonic undulator in the presence dual non periodic constant magnetic field. Electron trajectories along the x and y direction has been determined analytical and numerical methods. Generalized Bessel function is used to determine the intensity of radiation and Simpson's numerical method of integration is used to find the effect of constant magnetic fields. Comparison with previous analysis has also been presented.  
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WEP1WD01
Injection Kicker and Pulser Development for ALS-U  
 
  • W.L. Waldron, S. De Santis, T.H. Luo, G.C. Pappas, C. Steier, C.A. Swenson
    LBNL, Berkeley, California, USA
 
  Funding: This work was supported by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
The upgrade of the Advanced Light Source (ALS) at LBNL to a diffraction limited storage ring (ALS-U) is an approved project that is currently in the conceptual design phase. There is a focused R&D program to develop critical components of the ALS-U design. The design includes swap-out on-axis injection with a fast stripline kicker as the key enabling technology. The development of the kicker and the associated pulser will be presented as well as results from installation and beam tests at the ALS.
 
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WEP1WD02
High Power RF Solid State Amplifiers for Accelerators and Storage Rings  
 
  • J. Jacob
    ESRF, Grenoble, France
 
  Solid state amplifiers (SSA) are being increasingly used instead of electronic vacuum tubes to feed accelerating cavities with radio frequency power in the 100 kW range. Power is obtained from the combination of hundreds of transistor amplifier modules. The dramatic evolution of SSA technology will be presented and illustrated with a number of examples from existing accelerator applications at various frequencies.  
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WEP1WD03
RF System for the Storage Ring and Linac of the Future Synchrotron Light Facility in Thailand  
 
  • N. Juntong, T. Chanwattana, K. Kittimanapun, T. Pulampong
    SLRI, Nakhon Ratchasima, Thailand
 
  The future synchrotron light facility in Thailand is in designing process, which has a goal to complete a detailed design report in 2018. The new light source will be a ring-based light source with the circumference of approximately 300m and an electron energy of 3GeV. The maximum beam current is 300mA with a beam emittance below 1.0 nm·rad. The accelerator is based on a full energy linac, which will utilize a S-band frequency structures. The RF system of the storage ring is based on 500MHz frequency. The EU-HOM damped cavity and the new SPring-8 design TM020 cavity is the choice of the storage ring cavity. The RF power transmitter can either be a high-power klystron (1 MW klystron) feed all RF cavities or a combination of low power IOTs or solid-state amplifiers feed each cavity. The high gradient S-band structure is considered as the main accelerating structure for linac. The RF power system for linac will base on klystron and a modular modulator. This paper presents details of RF systems options for this new light source project.  
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WEP2PT030 Undulator Development Activities at DAVV-Indore 133
 
  • M. Gehlot, R. Khullar, G. Mishra
    Devi Ahilya University, Indore, India
  • H. Jeevakhan
    NITTTR, Bhopal, India
  • G. Sharma
    RI Research Instruments GmbH, Bergisch Gladbach, Germany
 
  Insertion Device Design Laboratory, DAVV has development activities on in-house design, fabrication and measurement of prototype undulators for synchrotron radiation and free electron laser application. The first prototype U50 was built with six periods, 50mm each period. It was PPM type. The next prototype U20 hybrid device based on NdFeB-Cobalt steel was built with aim to produce 0.24T to 0.05T in 10-20mm gap. The undulator is a 20mm period and there are 25 periods. The next one is U50-II PPM structure with 20 periods. In this paper we review the designs of all these undulators and briefly outline the user facilities of Hall probe bench, Pulsed wire bench and stretched wire magnetic measurement systems at IDDL.  
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WEP2PT033 Conceptual Design of Superconducting Transverse Gradient Undulator for PAL-XFEL Beamline 142
 
  • S.J. Lee, J.H. Han
    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, ICT \& Future Planning(2017R1C1B1012852)
Recently, the transverse gradient undulator (TGU) applications are suggested from the laser plasma wake-field accelerator (LPWA) to ultimate storage ring (USR). Especially for X-ray FEL, TGU can be used to generate the large bandwidth radiation (up to §I10{\percent}). In this proceeding, the review of PAL-XFEL beam parameters and TGU requirements was done to apply a variable large bandwidth operation to the PAL-XFEL beamlines. Also, the conceptual design of TGU, based on superconducting undulator (SCU) was proposed, and B-field calculation results were introduced for PAL-XFEL large bandwidth operation mode.
 
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WEP2PT034 Beyond Uniform Ellipsoidal Laser Shaping for Beam Brightness Improvements at PITZ 146
 
  • H.J. Qian, J.D. Good, C. Koschitzki, M. Krasilnikov, F. Stephan
    DESY Zeuthen, Zeuthen, Germany
 
  In the last decades, photoinjector brightness has improved significantly, driven by the needs of free electron lasers and many other applications. One of the key elements is photocathode laser shaping for reducing emittance growth from nonlinear space charge forces. At the photoinjector test facility at DESY in Zeuthen (PITZ), a uniform flattop laser was used to achieve record low emittance for a bunch charge from 20 pC to 1 nC. Due to the ideal 3D space charge force linearization in ellipsoidal electron bunches, uniform ellipsoidal photocathode laser shaping were proposed to improve beam emittance up to 33% for 1 nC beam at PITZ. In this paper, we will show even further transverse emittance improvements in simulations for both flattop and ellipsoidal laser pulses with parabolic radial distribution, versus uniform distributions. The laser shaping effects on longitudinal phase space are also discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-WEP2PT034  
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THP1WD01
Review of CW Guns for XFEL  
 
  • F. Zhou
    SLAC, Menlo Park, California, USA
 
  Normal conducting RF gun as well as DC gun and superconducting RF gun are the potential technologies for generation of high-brightness beam for the CW XFELs. This talk will firstly review the three gun technologies in term of beam performances, advantages and disadvantages. LCLS-II has chosen normal conducting RF gun for the CW photoinjector. We will then update LCLS-II injector design, construction, and commissioning which is expected to start in March 2018.  
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THP1WD02 LCLS-II Beam Containment System for Radiation Safety 187
 
  • C.I. Clarke, J. Bauer, M. Boyes, Y. Feng, A.S. Fisher, R.A. Kadyrov, J.C. Liu, E. Rodriguez, M. Rowen, M. Santana-Leitner, F. Tao, J.J. Welch, S. Xiao
    SLAC, Menlo Park, California, USA
  • T.L. Allison, J. Musson
    JLab, Newport News, Virginia, USA
 
  Funding: Work supported by the U.S. Department of Energy under contract number DE-AC02-76SF00515 and DE-AC05-06OR23177.
LCLS-II is a new xFEL facility under construction at SLAC National Accelerator Laboratory with a superconducting electron linac designed to operate up to §I{1.2}{MW} of beam power. This generates more serious beam hazards than the typical sub-kW linac operation of the existing xFEL facility, Linac Coherent Light Source (LCLS). SLAC uses a set of safety controls termed the Beam Containment System (BCS) to limit beam power and losses to prevent excessive radiation in occupied areas. The high beam power hazards of LCLS-II necessitate the development of new BCS devices and a larger scale deployment than previously done at LCLS. We present the new radiation hazards introduced by LCLS-II and the design development for the BCS.
 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-THP1WD02  
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THP1WD03
The High Brightness Photoinjector Electron Beam of the APS Linac  
 
  • Y. Sun, W. Berg, J.M. Byrd, J.C. Dooling, D. Hui, A. Zholents
    ANL, Argonne, Illinois, USA
  • S. Shin
    PAL, Pohang, Kyungbuk, Republic of Korea
 
  Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02- 06CH11357.
The Advanced Photon Source (APS) linac is mainly used to accelerate electron beams generated by a thermionic RF gun for APS storage ring operation. In 2014, a high-gradient S-band Photo-Cathode Gun (PCG) was installed at the front end of the linac, expanding the linac's capability to include high brightness photo-electron beams. In 2017, the interleaving operation of the thermionic and PC gun beams in the linac during the storage ring top-up operation was successfully commissioned. The interleaving operation enabled the PCG beam's availability to year-round. For the R&D towards future light sources, a new beam line at the Linac Extension Area (LEA) is being designed and constructed to support advanced accelerator technology and beam physics experiments. In this paper, we report our photo-cathode injector design, present the experimental measurements of beam properties at the APS linac, and compare the results with numerical simulations. Optimization for the first experiment at LEA using the high brightness photo-cathode electron beam is discussed, as well as an outlook for future potential experiments at LEA.
 
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THP2WD01 Construction and Optimization of Cryogenic Undulators at SOLEIL 193
 
  • M. Valléau, P. Berteaud, F. Briquez, P. Brunelle, N. Béchu, M.-E. Couprie, J. Da Silva Castro, J.M. Dubuisson, A. Ghaith, C. Herbeaux, J. Idam, C.A. Kitegi, F. Lepage, A. Lestrade, M. Louvet, O. Marcouillé, F. Marteau, A. Mary, A. Nadji, L.S. Nadolski, P. Rommeluère, M. Sebdaoui, A. Somogyi, K.T. Tavakoli, M. Tilmont, T. Weitkamp
    SOLEIL, Gif-sur-Yvette, France
 
  Funding: Synchrotron SOLEIL, L'Orme des Merisiers, 91 192 BP 34 Gif-sur-Yvette, France,
With permanent magnets undulator operation at cryogenic temperature, the magnetic field and the coercivity can be enhanced, enabling shorter periods with high magnetic fields. The first full scale (2 m long, 18 mm period) hybrid cryogenic undulator [1] using PrFeB [2] magnets operating at 77 K was installed at SOLEIL in 2011. Photon spectra measurements, in good agreement with the ex-pectations from magnetic measurements, were used for precise alignment and taper optimization. The second and third 18 mm PrFeB cryogenic undulators, modified to a half-pole/magnet/half-pole structure, were optimized without any magnet or pole shimming after assembly but mechanical sortings and some geometrical corrections had been done before assembly. A systematic error on individual magnets on the third U18 was also compensated. In-situ measurement benches, including a Hall probe and a stretched wire to optimize the undulator field at room and cryogenic temperature are presented. An upgrade of these in-situ benches will be detailed with the fabrication of a 15 mm 3 m long PrFeB cryogenic undulator at SOLEIL.
[1] C. Benabderrahmane, M. Valléau, M. E. Couprie, Phys. Rev. Accel. Beams 20, 033201(2017)
[2] C. Benabderrahmane, M. Valléau, M. E. Couprie, NIMA 669, 1-6, (2012)
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-FLS2018-THP2WD01  
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THP2WD02
Optimisation of Superconducting Undulators for X-ray FELs  
 
  • J.A. Clarke
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
 
  When superconducting undulators (SCUs) are optimised specifically for Free Electron Lasers (FELs) rather than storage rings a number of interesting implications emerge. In particular these relate to the vacuum requirement, the heat deposition within the SCU due to wakefield effects, and the undulator geometry itself. The impact of these considerations is that the peak field level achievable in an SCU specifically optimised for an FEL is significantly enhanced. For example, a planar SCU, utilising NbTi, with a 15mm period and 5mm aperture optimised for an FEL instead of a storage ring will generate a peak field of 2.1T compared to 1.4T. This radical increase in undulator performance will have a major impact on the optimisation of future X-ray FELs. This paper describes how an SCU for an X-ray FEL will be able to generate magnetic field levels far beyond those currently foreseen by any other magnet technology. It will also describe the prototype SCU being assembled now in the UK and the planned demonstration with beam on the CLARA test accelerator in early 2018.  
slides icon Slides THP2WD02 [9.412 MB]  
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THP2WD03
Partial Coherence in Undulator Beamlines at Ultra-low Emittance Storage Rings  
 
  • M. Sanchez del Rio
    ESRF, Grenoble, France
 
  The modelling of the radiation through the beamline is essential when dealing with synchrotron beamlines. Incoherent radiation from synchrotron can be analyzed using methods such as Monte Carlo ray tracing. Coherent radiation is analyzed by physical optics. None of these methodologies can be directly applied to partial coherence without some approximations. We introduced a new exact numerical method based on its decomposition in coherent modes for fully calculating the cross spectral density of the synchrotron radiation*. All parameters of the beam can be calculated from the numeric decomposition using COMSYL**. Moreover, the spectrum of the modes along the beamline gives additional precious information, as it is a direct measure of how much coherence has the beam. Coherent fraction becomes a natural measure of the amount of coherence in the beam. Some examples of simulations for the EBS (Extreme Brilliant Source) under construction at ESRF are shown.
* Glass, M. & Sanchez del Rio, M (2017) EPL 119 34004
** github.com/mark-glass/comsyl
 
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FRA2PL01
Summary Report: Key Technologies  
 
  • J. Pflüger
    XFEL. EU, Schenefeld, Germany
 
  This is the summary report of the key technologies working group.  
slides icon Slides FRA2PL01 [5.631 MB]  
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