TH1AA —  Plenary Session 9   (01-Sep-22   08:30—10:30)
Chair: R.E. Laxdal, FRIB, East Lansing, Michigan, USA
Paper Title Page
TH1AA01
 Nitrogen Gas-Jet Curtain for Windowless Helium Gas Cell Equipped With Differential Pumping Systems  
 
  • H. Imao
    RIKEN Nishina Center, Wako, Japan
  
  Windowless helium gas cells are used for heavy ion beam charge strippers, high intensity beam targets, and GARIS (GAs-filled Recoil Ion Separator) for nuclear physics experiments. They are usually accompanied by a differential pumping system, but due to the high diffusion rate of helium gas, helium gas diffuses into the region where a high vacuum is required, and as a result, it is difficult to increase the helium gas pressure. To solve this problem, we invented the "nitrogen gas curtain". This not only prevents helium gas from leaking out to the high vacuum side, but also allows nitrogen to leak out instead of helium, making it easier to increase the vacuum level. This system has been incorporated into the gas stripper and the GARIS-3 apparatus at the RIKEN RIBF and continues to operate stably. In this talk, the concept, design method, utility, and performance of the nitrogen gas curtain will be explained in detail*.
* RIKEN Accel. Prog. Rep. 52 (2019) p.14 		 
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slides icon Slides TH1AA01 [18.645 MB]  
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TH1AA02 Developments Towards FRIB Upgrade to 400 MeV/u for Heaviest Uranium Ions 653
 
  • K.E. McGee, K. Elliott, A. Ganshyn, W. Hartung, S.H. Kim, P.N. Ostroumov, J.T. Popielarski, L. Popielarski, A. Taylor, T. Xu
    FRIB, East Lansing, Michigan, USA
  • G.V. Eremeev, F. Furuta, M. Martinello, O.S. Melnychuk, A.V. Netepenko
    Fermilab, Batavia, Illinois, USA
  • B.M. Guilfoyle, M.P. Kelly, T. Reid
    ANL, Lemont, Illinois, USA
  
  High-Q0 medium-velocity (beta opt = 0.6) 5-cell elliptical cavities for superconducting linacs are critical technology for advancing current and future projects such as the Proton Improvement Plan II linac and the proposed energy upgrade of Michigan State University’s Facility For Rare Isotope Beams linac, FRIB400. Previous work established the validity of the novel geometry of the FRIB400 prototype 644 MHz 5-cell elliptical β = 0.65 cavities for future high Q0 development. In collaboration with FNAL, two leading-edge high-Q0 recipes, N-doping and Mid-T baking, were tested in the 5-cell format. 2/0 N-doping + cold electropolishing was successful at achieving FRIB400 and PIP-II Q0 requirements, achieving an unprecedented 3.8 x 1010 at 17.5 MV/m, satisfying the FRIB400 Q0 requirements by 1.75 times in a low-gauss environment. Mid-T baking exceeded FRIB400 Q0 requirements by 1.4 times, and benefitted from decreased residual resistance compared to the N-doped cavity test. Systematic ultrasonic thickness measurements in single-cell revealed bulk (150 microns) EP with the modified EP tool is consistent across the inner surfaces of the cavity walls.  
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slides icon Slides TH1AA02 [44.708 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TH1AA02  
About • Received ※ 11 August 2022 — Revised ※ 22 August 2022 — Accepted ※ 23 September 2022 — Issue date ※ 14 October 2022
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TH1AA03 Accelerator development for Global Security 657
 
  • S. Biedron
    Element Aero, Chicago, USA
  
  Many facilities and projects in global security have to do with global security concerns. From direct interrogation to radiation testing, there are myriad of security applications of particle accelerators. . This paper will review accelerator design and technology development including novel sources being developed.  
slides icon Slides TH1AA03 [24.972 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TH1AA03  
About • Received ※ 31 August 2022 — Revised ※ 06 September 2022 — Accepted ※ 16 September 2022 — Issue date ※ 23 September 2022
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TH1AA04 Spatiotemporal Structure in Intense THz Pulsed Beams 663
 
  • G.A. Hine
    ORNL, Oak Ridge, Tennessee, USA
  
  Optically generated terahertz radiation, with gigavolt per meter (GV/m) electric fields accessible in tabletop experiments, provides a promising source of accelerating gradients for future particle accelerator applications. Manipulation and characterization of radiation is essential for efficiently producing high fields and effectively delivering them to an accelerating structure or interaction region. The talk will cover a method of generating and characterizing high quality and structured terahertz pulsed laser beams for compact particle acceleration.  
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slides icon Slides TH1AA04 [1.126 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TH1AA04  
About • Received ※ 23 August 2022 — Revised ※ 07 September 2022 — Accepted ※ 26 September 2022 — Issue date ※ 12 October 2022
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TH1AA05 R&D of Liquid Lithium Stripper at FRIB 668
 
  • T. Kanemura, N.K. Bultman, R. Madendorp, F. Marti, T. Maruta, Y. Momozaki, J.A. Nolen, P.N. Ostroumov, A.S. Plastun, J. Wei, Q. Zhao
    FRIB, East Lansing, Michigan, USA
  • D.B. Chojnowski, Y. Momozaki, J.A. Nolen, C.B. Reed, J.R. Specht
    ANL, Lemont, Illinois, USA
  • M.J. LaVere
    MSU, East Lansing, Michigan, USA
  
  Funding: The U.S. Department of Energy, Office of Science, Office of Nuclear Physics. The Facility for Rare Isotope Beams (FRIB) is a DOE Office of Science User Facility under Award Number DE-SC0000661
Charge stripping is one of the most important processes in the acceleration of intense heavy ion beams, and the charge stripper greatly affects the performance of the accelerator facility. In this talk, the design method and the achieved performance of the liquid lithium stripper recently developed for FRIB will be reported. 		 
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slides icon Slides TH1AA05 [1.663 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TH1AA05  
About • Received ※ 10 August 2022 — Revised ※ 20 August 2022 — Accepted ※ 31 August 2022 — Issue date ※ 16 September 2022
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TH1AA06 Low Level RF Control Algorithms for the CERN Proton LINAC4 673
 
  • P. Baudrenghien, B. Bielawski, R.B. Borner
    CERN, Meyrin, Switzerland
  
  The CERN Linac4 Low Level RF (LLRF) uses a Linear Gaussian Regulator and an Adaptive Feed Forward to regulate the accelerating field in the cavities in the presence of strong beam loading. A Klystron Polar Loop is also implemented to compensate the RF perturbations caused by the ripples and droop in the klystron High Voltage supply. The talk presents the important parts of the regulation, shows results as the system has evolved from first prototype (2013) to operational beams (2020), and mentions some important issues encountered during the commissioning and the first years of operation, with their mitigations.  
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slides icon Slides TH1AA06 [4.183 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TH1AA06  
About • Received ※ 24 August 2022 — Revised ※ 31 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 06 September 2022
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