FRXB —  Friday Oral Parallel B   (28-May-21   10:00—11:00)
Paper Title Page
FRXB01
The Progress of the In-Vacuum Superconducting Undulator Prototype for SHINE Project  
 
  • Q.G. Zhou
    SSRF, Shanghai, People’s Republic of China
 
  The superconducting undulator can generate the highest peak field with the short period length and give the desirable K value, thus producing the high-intensity high-energy radiation photons. The Shanghai High Repetition rate XFEL and Extreme Light (SHINE) facility will use 40 superconducting undulators with 4m long for each to produce the vertically polarized photons with energy of 10keV-25keV. The period length of undulators is 16mm, the magnetic gap is 5mm and the peak field is 1.58T. Each undulator contains 504 vertical racetrace coils made of NbTi wires which are wound on 504 active poles. A 65K shielding is designed to reduce the thermal radiation from the vacuum chamber. The cooling of the magnet is forced by the liquid helium pipes which are installed in the middle of the magnet yoke surface and the sides of the gap in the direction of the electron beam. There is no beam vacuum chamber due to the small magnetic gap. A prototype of 4m long is being manufactured before the mass production and will be finished this year. The paper will describe the design parameters, the configuration of the prototype and the test plan of this year.  
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FRXB02 Development of 36 GHz RF Systems for RF Linearisers 4518
 
  • A. Castilla, G. Burt
    Lancaster University, Lancaster, United Kingdom
  • M. Behtouei, B. Spataro
    INFN/LNF, Frascati, Italy
  • G. Burt
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • J.C. Cai, A. Castilla, A. Latina, X. Liu, I. Syratchev, X.W. Wu, W. Wuensch
    CERN, Geneva, Switzerland
  • J.C. Cai, A. Castilla
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • A.W. Cross, L. Zhang
    USTRAT/SUPA, Glasgow, United Kingdom
  • L.J.R. Nix
    University of Strathclyde, Glasgow, United Kingdom
 
  Funding: This project has received funding from the European Union’s Horizon2020 research and innovation programme under grant agreement No 777431.
As part of the deign studies, the CompactLight project plans to use an injector in the C-band. Which constitutes a particular complication for the harmonic system in charge of linearising the beam’s phase space, since it means its operation frequency could be higher than the standard X-band RF technologies. In the present work, we investigated a 36 GHz (Ka-band) as the ideal frequency for the harmonic system. A set of structure designs are presented as candidates for the lineariser, based on different powering schemes and pulse compressor technologies. The comparison is made both in terms of beam dynamics and RF performance. Given the phase stability requirements for the MW class RF sources needed for this system, we performed careful studies of a Gyro-Klystron and a multi-beam klystron as potential RF sources, with both showing up to 3 MW available power using moderate modulator voltages. Alternatives for pulse compression at Ka-band are also discussed in this work.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-FRXB02  
About • paper received ※ 17 May 2021       paper accepted ※ 19 July 2021       issue date ※ 25 August 2021  
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FRXB03
MgB₂ Based High-Current Power Transmission Lines for the HL-LHC Magnets: From Concept to Prototype Validation  
 
  • A. Ballarino
    CERN, Geneva, Switzerland
 
  The powering of the HL-LHC magnets requires transferring multiple large quasi-DC currents from the power converters, located in new radiation-free underground galleries, to the magnets. Superconducting power transmission lines based on MgB2 superconductor, called Superconducting Links, ensure the electrical transmission from the current leads, near the power converters, to the magnets in the LHC main tunnel. They span a physical distance of up to about 120 metres, snaking through a complex underground environment that includes a vertical path of about 10 metres, and transfer DC currents totalling up to 120 kA at temperatures of up to 25 K. This paper summarizes the development done in order to conceive, construct and industrialize cold powering systems including 100 kA Superconducting Links. The systems, which are cooled by the forced flow of helium gas, incorporate HTS REBCO based current leads and Nb-Ti terminations for the connection to the magnets’ busbars. Demonstrator cold powering systems were recently constructed and tested at CERN in nominal and transient conditions representative of the final operation modes. The results from these tests are also presented and discussed.  
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FRXB04 Newly Development of Ceramics Chamber with Integrated Pulsed Magnet for Super-Narrow Bore in KEK-PF 4524
 
  • C. Mitsuda, K. Harada, Y. Kobayashi, S. Nagahashi, T. Nogami, T. Obina, R. Takai, H. Takaki, T. Uchiyama, A. Ueda
    KEK, Ibaraki, Japan
  • K. Hamaji, K. Iwamoto, A. Sasagawa, A. Yokoyama
    KYOCERA Corporation, Higashiomi-city, Shiga, Japan
  • Y. Lu
    Sokendai, Ibaraki, Japan
 
  Ceramics chamber with integrated pulsed magnet (CCiPM) is a new air-core type magnet that has a plan to be used as a multipole injection magnet, a dipole injection kicker, and a fast correction kicker in the next-generation light source. The magnet coils are implanted completely into the thickness of cylindrical ceramic and integrated with ceramic structurally. The first CCiPM was developed for an internal diameter of 60 mm as a magnet bore to establish the basic production techniques. The technique has been enhanced to realize narrower bore over 3 years, and finally, the achieved internal diameters were 40 and 30 mm in newly developed CCiPM. These super small bores have an expectation to conform to the size of the vacuum beam duct in the ring of a future light source. New CCiPMs are under the off-line test to confirm the vacuum durability, electrical characteristics, and magnetic performance, and the beam test for the CCiPM with 30 mm diameter has also proceeded in parallel. The points of production technique and the recent results of the off-line test will be presented in this conference.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-FRXB04  
About • paper received ※ 19 May 2021       paper accepted ※ 19 July 2021       issue date ※ 31 August 2021  
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FRXB05 Muon Ionization Cooling Experiment: Results & Prospects 4528
 
  • C.T. Rogers
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
 
  A high-energy muon collider could be the most powerful and cost-effective collider approach in the multi-TeV regime, and a neutrino source based on decay of an intense muon beam would be ideal for measurement of neutrino oscillation parameters. Muon beams may be created through the decay of pions produced in the interaction of a proton beam with a target. The muons are subsequently accelerated and injected into a storage ring where they decay producing a beam of neutrinos, or collide with counter-rotating antimuons. Cooling of the muon beam would enable more muons to be accelerated resulting in a more intense neutrino source and higher collider luminosity. Ionization cooling is the novel technique by which it is proposed to cool the beam. The Muon Ionization Cooling Experiment collaboration constructed a section of an ionization cooling channel and used it to provide the first demonstration of ionization cooling. Here the observation of ionization cooling is described. The cooling performance is studied for a variety of beam and magnetic field configurations. The outlook for muon ionization cooling demonstrations is discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-FRXB05  
About • paper received ※ 19 May 2021       paper accepted ※ 19 July 2021       issue date ※ 23 August 2021  
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FRXB06
Direct response time measurements on semiconductor photocathodes  
 
  • G. Loisch, M. Groß, D.K. Kalantaryan, C. Koschitzki, M. Krasilnikov, X. Li, O. Lishilin, D. Melkumyan, R. Niemczyk, A. Oppelt, H.J. Qian, F. Stephan, G. Vashchenko, T. Weilbach
    DESY Zeuthen, Zeuthen, Germany
  • Y. Chen, S. Lederer
    DESY, Hamburg, Germany
  • L. Monaco, D. Sertore
    INFN/LASA, Segrate (MI), Italy
  • R. Valizadeh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
 
  Semiconductor photocathodes like Cs2Te enable stable electron sources with high photon to electron conversion rate (quantum efficiency, QE) for high brightness photoinjectors. Besides QE, work function and vacuum stability, bunch lengthening is a key figure of merit for these sources, resulting from UV photon penetration into the semiconductor and scattering of excited electrons before emission. These processes and their statistical variation lead to a delay, as well as to lengthening of the extracted electron bunch w.r.t. the incident laser pulse, often referred to as "response time". Thus far, no direct measurement of the response time of Cs2Te, one of the most widely used cathode materials, has been reported. As such a measurement is crucial for photocathode laser based bunch shaping, short bunch applications, emission modeling and for evaluating new cathode materials like CsKSb, a measurement procedure has been established at the photoinjector test facility at DESY in Zeuthen (PITZ) to measure longitudinal bunch shape variation due to cathode emission effects. Here, we introduce the method and show first results on direct cathode response measurements of Cs2Te cathodes.  
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FRXB07 Injector Optimization for the IR-FEL Operation at the Compact ERL at KEK 4531
 
  • O.A. Tanaka, N. Higashi, T. Miyajima
    KEK, Ibaraki, Japan
 
  Funding: Work supported by NEDO project "Development of advanced laser processing with intelligence based high-brightness and high-efficiency laser technologies (TACMI project)".
The Compact Energy Recovery Linac (cERL) at KEK is a test accelerator to develop ERL technologies and to operate with a high average beam current and a high beam quality. cERL consists of a photoinjector, a main linac for energy recovery, a recirculation loop and a beam dump. A recent upgrade of the cERL to the middle Infrared Free Electron Laser (IR-FEL) imposed new conditions to maintain beam parameters. Therefore, the injector should be optimized to meet the following requirements at the exit of the main linac. The rms bunch length should be 2 ps, the rms longitudinal emittance should be kept the least, and simultaneously the rms transverse emittance should be kept less than 3 c mm mrad. In this work we describe the strategy and results of the injector optimization to achieve the better performance of the cERL-FEL.
 
slides icon Slides FRXB07 [3.450 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-FRXB07  
About • paper received ※ 19 May 2021       paper accepted ※ 22 July 2021       issue date ※ 14 August 2021  
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