THPTEV —  Thursday Poster SRF Technology   (01-Jul-21   11:10—12:10)
Paper Title Page
  • K. Ozeki, O. Kamigaito, N. Sakamoto, K. Suda, K. Yamada
    RIKEN Nishina Center, Wako, Japan
  In RIKEN, three cryomodules which contain ten SC-QWRs in total (4 + 4 + 2) were constructed, and beam supply has been started since last year. The FPCs for RIKEN QWR have a disk-type single vacuum window at room-temperature region. A vacuum leakage occurred at one FPC, after 4th cool-down test. In addition, second vacuum leakage occurred at another FPC, after starting beam supply. A dew condensation at air side of vacuum window may degrade the brazing of vacuum window. In order to prevent a dew condensation and to restore damaged FPCs, an additional outer vacuum window using machinable ceramics was designed and attached to the FPCs. In this contribution, a structure of the FPC, troubles, provision for those troubles, and plan for reconstruction are reported.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2021-THPTEV001  
About • Received ※ 22 June 2021 — Revised ※ 26 November 2021 — Accepted ※ 18 January 2022 — Issue date ※ 12 May 2022
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THPTEV002 Enhanced Pneumatic Tuner Control for FRIB Half-Wave Resonators 829
  • W. Chang, W. Hartung, S.H. Kim, J.T. Popielarski, T. Xu, C. Zhang, S. Zhao
    FRIB, East Lansing, Michigan, USA
  The superconducting driver linac for the Facility for Rare Isotope Beams (FRIB) includes a total of 46 cryomodules; 31 cryomodules contain half-wave resonators (HWRs) with pneumatic tuners. Pneumatic tuner control is via solenoid valves connecting the tuner to a helium gas supply manifold and a gas return line. For precise compensation of cavity detuning over a small range, the control voltage for the solenoid valves must be calibrated. Some valves have hysteresis in the gas flow rate as a function of control voltage, such that their response may be nonlinear and not repeatable–this makes the control algorithm challenging. To improve the system performance, a new pneumatic tuner control system was developed which regulates the position of one stepper motor instead of the two solenoid valves.  
poster icon Poster THPTEV002 [1.325 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2021-THPTEV002  
About • Received ※ 24 June 2021 — Revised ※ 15 December 2021 — Accepted ※ 17 February 2022 — Issue date ※ 16 May 2022
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THPTEV003 LCLS-II Cryomodules Production Experience and Lessons Learned Towards LCLS-II-HE Project 832
  • T.T. Arkan, D.J. Bice, J.N. Blowers, C.J. Grimm, B.D. Hartsell, J.A. Kaluzny, M. Martinello, T.H. Nicol, Y.M. Orlov, S. Posen, K.S. Premo, R.P. Stanek
    Fermilab, Batavia, Illinois, USA
  Funding: DOE
LCLS-II is an upgrade project for the linear coherent light source (LCLS) at SLAC. The LCLS-II linac consists of thirty-five 1.3 GHz and two 3.9 GHz superconducting RF (SRF) continuous wave (CW) cryomodules with high quality factor cavities. Cryomodules were produced at Fermilab and at Jefferson Lab in collaboration with SLAC. Fermilab successfully completed the assembly, testing and delivery of seventeen 1.3 GHz and three 3.9 GHz cryomodules. LCLS-II-HE is a planned upgrade project to LCLS-II. The LCLS-II-HE linac will consist of twenty-three 1.3 GHz cryomodules with high gradient and high quality factor cavities. This paper presents LCLS-II-HE cryomodule production plans, emphasizing the improvements done based on the challenges, mitigations, and lessons learned from LCLS-II.
poster icon Poster THPTEV003 [0.620 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2021-THPTEV003  
About • Received ※ 21 June 2021 — Revised ※ 11 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 27 October 2021
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THPTEV004 Surface Oxides on Nb and Nb₃Sn Surfaces: Toward a Deeper Understanding 836
  • Z. Sun, M. Liepe, T.E. Oseroff, R.D. Porter
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • T. Arias, Z. Baraissov, D.A. Muller, N. Sitaraman
    Cornell University, Ithaca, New York, USA
  • C. Dukes
    University of Virginia, Charlottesville, Virginia, USA
  • D. Johnson-McDaniel, M. Salim
    CCMR, Ithaca, New York, USA
  Surface oxides on Nb and Nb3Sn SRF cavities, as a thin ’dirty’ layer, could be critical to their performance as suggested by recent theory. Although these oxides have been studied in the past, we intend here to provide a deeper understanding based on a systematic study on coupon samples that have been processed under the different conditions currently used in SRF cavity treatments. Our aim is to obtain a more complete picture of the oxide evolution. This then might help to explain the observed cavity performance variation, and might allow designing a process to achieve a designed, optimized surface with controlled oxides types and thickness. We find that the surface oxides are in amorphous phase that exhibits normal conducting behaviors, while the pentoxide further degrades with time. Also, we observed a thin hydroxide layer on the outermost surface and possibly Nb(OH)x motifs in the bulk. Moreover, distinctive oxide structures were found in Nb3Sn samples from vapor diffusion, electroplating, and sputtering. The semiconducting SnOx appeared through the oxide depth in vapor diffused Nb3Sn, while a ~1 nm SnOx layer merely exists at the outermost surface of electroplated Nb3Sn.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2021-THPTEV004  
About • Received ※ 09 July 2021 — Revised ※ 11 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 04 November 2021
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THPTEV006 Design of the PIP-II 650 MHz Low Beta Cryomodule 841
  • N. Bazin, S. Berry, G. Maitre, O. Napoly, C. Simon
    CEA-DRF-IRFU, France
  • S. Bouaziz, R. Cubizolles, M. Lacroix
    CEA-IRFU, Gif-sur-Yvette, France
  • S.K. Chandrasekaran, Y.M. Orlov, V. Roger
    Fermilab, Batavia, Illinois, USA
  The Proton Improvement Plan II (PIP-II) that will be installed at Fermilab is the first U.S. accelerator project that will have significant contributions from international partners. CEA joined the international collaboration in 2018, and is responsible of the 650 MHz low-beta section made of 9 cryomodules, with the design of the cryostat (i.e the cryomodule without the cavities, the power couplers and the frequency tuning systems) and the manufacturing of its components, the assembly and tests of the pre-production cryomodule and the 9 series ones. This paper will present the design of the 650 MHz low-beta cryomodule.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2021-THPTEV006  
About • Received ※ 02 July 2021 — Accepted ※ 30 January 2022 — Issue date ※ 01 May 2022  
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THPTEV008 Development of a Digital LLRF System for SRF Cavities in RAON Accelerator 845
  • H. Jang, D.H. Gil, Y. Jung, H. Kim, Y. Kim, M. Lee
    IBS, Daejeon, Republic of Korea
  An ion accelerator, RAON is planned and under construction in Daejeon, Korea by Rare Isotope Science Project (RISP) team in Institute of Basic Science (IBS). The purpose of this accelerator is the generation of rare isotope by ISOL (Isotope Separation On-Line) and IF (In-flight Fragmentation) method. To achieve this goal RAON adopted the superconducting cavities at three different frequency (81.25 MHz, 162.5 MHz and 325 MHz) and their RF field will be controlled independently for the acceleration of ions with various A/q. A solid state power amplifier and a low level RF (LLRF) controller pairs are under development to generate and to control the RF for the cavities. Recently the development and evaluation of the digital-based LLRF have been performed. For the operation and test of SRF cavities, self-excited loop (SEL) and generator-driven-resonator (GDR) algorithm is digitally implemented and its test was performed. In this paper the status and test result of RAON LLRF controller will be described.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2021-THPTEV008  
About • Received ※ 21 June 2021 — Revised ※ 30 August 2021 — Accepted ※ 26 September 2021 — Issue date ※ 23 November 2021
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THPTEV011 Experimental Validation of the Use of Cold Cathode Gauge inside the Cryomodule Insulation Vacuum 848
  • H. Jenhani, P. Carbonnier
    CEA-IRFU, Gif-sur-Yvette, France
  The Proton Improvement Plan - II (PIP-II) project is underway at Fermilab with an international collaboration involving CEA in the development and testing of 650 MHz cryomodules. The risk analysis related to cryomodule operation proposed to add a vacuum gauge on the power coupler to prevent the untimely rupture of its ceramic. Due to the advanced design of the cryomodules, the gauge needs to be integrated inside the insulation vacuum to reduce the impact of this new modification. The lack of experience feedback on a similar operating condition requires an experimental validation before the implementation. This article details the experimental tests carried out before the approval of this solution.  
poster icon Poster THPTEV011 [0.664 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2021-THPTEV011  
About • Received ※ 21 June 2021 — Revised ※ 16 August 2021 — Accepted ※ 23 November 2021 — Issue date ※ 15 January 2022
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THPTEV012 Substitution of Spring Clamps for Bolts on SRF Cavity Flanges to Minimize Particle Generation 853
  • G.H. Biallas
    Hyperboloid LLC, Yorktown, Virginia, USA
  • E. Daly, K. Macha, C.E. Reece
    JLab, Newport News, Virginia, USA
  Funding: Funding supplied by US Department of Energy SBIR Grant #DE-SC0019579
Hyperboloid LLC developed and successfully tested a System of High Force Spring Clamps to substitute, one for one, for bolts on the flanges of SRF Cavities. The Clamps are like exceptionally forceful binder clips. The System, that includes the Hydraulic Openers that apply the clamps, minimizes generation of particulates when sealing cavity flanges. Hyperboloid LLC used ANSYS to design the titanium clamps that generate the force to seal the hexagonal cross section, relatively hard aluminum gasket developed for TESLA and used at JLab and other accelerators. The System is developed to be suitable for use in SRF Clean Rooms. Results of particle counter readings during bolt and clamp installation and superfluid helium challenges to the sealed flanges are discussed. Results of a half-size clamp that could seal a soft aluminum gasket and the attempt to seal a gasket made of niobium are also discussed.
L. Monaco, P. Michelato, C. Pagani, N. Panzeri, Experimental and Theoretical Analysis of Tesla-like SFRF Cavity Flanges, INFN Milano- LASA, I-20090 Segrate (MI), Italy. Proc. EPAC 2006, Edinburgh, SC
poster icon Poster THPTEV012 [1.404 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2021-THPTEV012  
About • Received ※ 21 June 2021 — Revised ※ 16 December 2021 — Accepted ※ 28 April 2022 — Issue date ※ 01 May 2022
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THPTEV013 LCLS-II Cryomodule Production at JLab: Summary and Lessons 858
  • N.A. Huque, E. Daly, J.P. Preble, K.M. Wilson
    JLab, Newport News, Virginia, USA
  Cryomodules for the Linear Coherent Light Source II (LCLS-II) at SLAC National Accelerator Laboratory were jointly fabricated at Thomas Jefferson National Accelerator Facility (JLab) and Fermi National Accelerator Facility (FNAL). Procurements, cavity testing, cryomodule assembly, and cryomodule testing were carried out at the two labs. Twenty-one 1.3 GHz cryomodules were fabricated at JLab. The LCLS-II cryomodules are based on the design used in the European X-Ray Free Electron Laser (XFEL) but modified for continuous wave operation. The higher performance requirements lead to challenges in cavity processing, microphonics, magnetic hygiene and cryomodule transportation. This paper outlines the cryomodule production experience at JLab, as well as improvements to procedures and infrastructure to overcome the performance challenges of the LCLS-II design.  
poster icon Poster THPTEV013 [2.446 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2021-THPTEV013  
About • Received ※ 21 June 2021 — Revised ※ 02 December 2021 — Accepted ※ 24 January 2022 — Issue date ※ 01 May 2022
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THPTEV014 Managing Procurements in the Time of Covid-19: SNS-PPU as a Case Study 863
  • K.M. Wilson, G. Cheng, E. Daly, N.A. Huque, T. Huratiak, M. Laney, K. Macha, D.J. Maddox, M. Marchlik, P.D. Owen, T. Peshehonoff, M. Torres, M. Wiseman
    JLab, Newport News, Virginia, USA
  Funding: Supported by the Dept of Energy, Office of Nuclear Physics under contract DE-AC05-06OR23177 (JSA); and by UT-B which manages Oak Ridge National Laboratory under contract DE-AC05-00OR22725.
In early 2020, COVID-19 swept across the world. The accelerator industry, like many others, was impacted by disease, delays, shortages, and new working conditions. All Thomas Jefferson National Accelerator Facility (JLab) employees were sent home in mid-March 2020, with many still working remotely now. At the time, JLab was working on the Proton Power Upgrade (PPU) to the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL). Procurements had been placed and were being managed, parts were being received and inspected. This paper details the JLab procurement plan for the SNS PPU project, and the mitigations that were developed to continue to support this project smoothly under the limitations imposed by COVID-19.
poster icon Poster THPTEV014 [1.081 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2021-THPTEV014  
About • Received ※ 15 June 2021 — Revised ※ 30 November 2021 — Accepted ※ 21 January 2022 — Issue date ※ 01 May 2022
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THPTEV015 Cylindrical Magnetron Development for Nb3sn Deposition via Magnetron Sputtering 868
  • Md.N. Sayeed, H. Elsayed-Ali
    ODU, Norfolk, Virginia, USA
  • C. Côté, M.A. Farzad, A. Sarkissian
    PLASMIONIQUE Inc., Varennes, Québec, Canada
  • G.V. Eremeevpresenter
    Fermilab, Batavia, Illinois, USA
  • A-M. Valente-Feliciano
    JLab, Newport News, Virginia, USA
  Funding: This work was supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under Contract No. DE-AC05-06OR23177.
Due to its better superconducting properties (critical temperature Tc~ 18.3 K, superheating field Hsh~ 400 mT), Nb3Sn is considered as a potential alternative to niobium (Tc~ 9.25 K, Hsh~ 200 mT) for superconducting radiofrequency (SRF) cavities for particle acceleration. Magnetron sputtering is an effective method to produce superconducting Nb3Sn films. We deposited superconducting Nb3Sn films on samples with magnetron sputtering using co-sputtering, sequential sputtering, and sputtering from a stoichiometric target. Nb3Sn films produced by magnetron sputtering in our previous experiments have achieved DC superconducting critical temperature up to 17.93 K and RF superconducting transition at 17.2 K. A magnetron sputtering system with two identical cylindrical cathodes that can be used to sputter Nb3Sn films on cavities has been designed and is under development now. We report on the design and the current progress on the development of the system.
poster icon Poster THPTEV015 [1.131 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2021-THPTEV015  
About • Received ※ 22 June 2021 — Revised ※ 12 August 2021 — Accepted ※ 21 August 2021 — Issue date ※ 27 September 2021
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THPTEV016 The Role of Oxygen Concentration in Enabling High Gradients in Niobium SRF Cavities 871
  • D. Bafia, A. Grassellino, A.S. Romanenko
    Fermilab, Batavia, Illinois, USA
  We studied the role of O concentration with depth in the performance of Nb SRF cavities. An ensemble of electropolished 1.3 GHz cavities, which initially showed high field Q-slope (HFQS), was subjected to sequential testing and treatment with in-situ low temperature baking at various temperatures. We find that increasing the bake duration causes (i) an increase in the onset of HFQS until it is absent up to quench (ii) a non-monotonic relationship with the quench field (iii) an evolution of the RBCS toward a non-equilibrium behavior that drives anti-Q slope. Our data is qualitatively explained by assuming an O diffusion model and suggests that the mitigation of HFQS that arises from 120°C in-situ LTB is mediated by the diffusion of O from the native oxide which prevents the precipitation of proximity-coupled Nb nano-hydrides, in turn enabling higher quench fields. The decrease in quench field for cavities in which O has been diffused >90 nm from the RF surface may be due to a reduction of the field limit in the SS bilayer structure. We also suggest that the evolution of the RBCS occurs due to the absence of proximity coupled inclusions, bringing about non-equilibrium effects.  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2021-THPTEV016  
About • Received ※ 22 June 2021 — Revised ※ 13 September 2021 — Accepted ※ 13 October 2021 — Issue date ※ 23 November 2021
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THPTEV017 Status of the LCLS-II-HE Project at Jefferson Lab 876
  • K.M. Wilson, J. Hogan, M. Laney, A.D. Palczewski, C.E. Reece
    JLab, Newport News, Virginia, USA
  Funding: This work was supported by the U.S. Department of Energy Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177 (JSA); and for BES under contract DE’AC02’76SF00515 (SLAC).
The Linac Coherent Light Source II High Energy (LCLS-II-HE) upgrade at the SLAC National Accelerator Laboratory is being constructed in partnership with the Thomas Jefferson National Accelerator Facility (JLab) and the Fermi National Accelerator Laboratory (FNAL). The cryomodule production scope consists of the design, procurement, construction, and acceptance testing of 24 eight-cavity, 1.3 GHz cryomodules, as well as R&D activities necessary to develop the required technology. To achieve this, JLab and FNAL are also contributing to SLAC’s effort to develop the cavity recipe and production processes necessary to meet the LCLS-II-HE goal of 20.8 MV/m and average Q0 of 2.7·1010. This paper details the JLab scope, focusing on the project initiation phase, in particular technology development and prototyping, project development and planning, and implementation of lessons learned from LCLS-II.
poster icon Poster THPTEV017 [1.536 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-SRF2021-THPTEV017  
About • Received ※ 21 June 2021 — Revised ※ 12 August 2021 — Accepted ※ 02 March 2022 — Issue date ※ 01 May 2022
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