Keyword: SRF
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MOPOST011 CEA Contribution to the PIP-II Linear Accelerator cryomodule, cavity, vacuum, linac 74
 
  • N. Bazin, J. Belorgey, S. Berry, J. Drant, O. Napoly, A. Raut, P. Sahuquet, C. Simon
    CEA-DRF-IRFU, France
  • S. Arsenyev, Q. Bertrand, P. Brédy, E. Cenni, C. Cloué, R. Cubizolles, H. Jenhani, S. Ladegaillerie, A. Le Baut, A. Moreau, O. Piquet
    CEA-IRFU, Gif-sur-Yvette, France
  • O. Napoly
    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 will deliver 10 low-beta cryomodules as In-Kind Contribution to the PIP-II project, with cavities supplied by LASA-INFN and power couplers and tuning systems supplied by Fermilab. This paper presents the CEA scope of work that includes the design, manufacturing, assembly and tests of the cryomodules and the upgrade of the existing infrastructures to the PIP-II requirements.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOST011  
About • Received ※ 13 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 25 June 2022
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MOPOST015 Beam Dynamics Simulations for the Superconducting HELIAC CW Linac at GSI cavity, heavy-ion, linac, cryomodule 86
 
  • M. Schwarz, T. Conrad, H. Podlech
    IAP, Frankfurt am Main, Germany
  • K. Aulenbacher, F.D. Dziuba, S. Lauber, J. List
    IKP, Mainz, Germany
  • K. Aulenbacher, W.A. Barth, M. Basten, C. Burandt, F.D. Dziuba, V. Gettmann, T. Kürzeder, S. Lauber, J. List, M. Miski-Oglu, S. Yaramyshev
    HIM, Mainz, Germany
  • K. Aulenbacher, W.A. Barth, M. Basten, C. Burandt, F.D. Dziuba, V. Gettmann, M. Heilmann, T. Kürzeder, S. Lauber, J. List, M. Miski-Oglu, A. Rubin, S. Yaramyshev
    GSI, Darmstadt, Germany
  • W.A. Barth
    KPH, Mainz, Germany
  • H. Podlech
    HFHF, Frankfurt am Main, Germany
 
  Funding: Work supported by the German Federal Ministry of Education and Research (BMBF, contract no. 05P21RFRB2)
The superconducting (SC) continuous wave (CW) heavy ion linac HELIAC (HElm\-holtz LInear ACcelerator) is a common project of GSI and HIM under key support of IAP Frankfurt. It is intended for future experiments with heavy ions near the Coulomb barrier within super-heavy element (SHE) research and aims at developing a linac with multiple CH cavities as key components downstream the High Charge State Injector (HLI) at GSI. The design is challenging due to the requirement of intense beams in CW mode up to a mass-to-charge ratio of 6, while covering a broad output energy range from 3.5 to 7.3 MeV/u with minimum energy spread. In 2017 the first superconducting cavity of the linac has been successfully commissioned and extensively tested with beam at GSI. In the light of experience gained in this research so far, the beam dynamics layout for the entire linac has been updated and optimized in the meantime. This contribution will provide a brief overview of the recent progress on the project, as well as a potential modification to the linac layout.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOST015  
About • Received ※ 08 June 2022 — Revised ※ 09 June 2022 — Accepted ※ 03 July 2022 — Issue date ※ 10 July 2022
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MOPOTK006 Off-Energy Operation for the ESRF-EBS Storage Ring optics, injection, sextupole, lattice 437
 
  • L. Hoummi, T. Brochard, N. Carmignani, L.R. Carver, J. Chavanne, S.M. Liuzzo, T.P. Perron, R. Versteegen, S.M. White
    ESRF, Grenoble, France
  • P. Raimondi
    SLAC, Menlo Park, California, USA
 
  The ESRF-EBS is the first 4th generation source making use of the Hybrid Multi-Bend Achromat (HMBA) lattice cell, reaching an equilibrium horizontal emittance of 140 pm.rad in user mode (insertion devices (ID) gaps open). The injection in the storage ring (SR) is conducted with a short booster, operated off-energy. The RF frequency is increased compared to the nominal one to put the beam on a dispersive orbit, thus going off-axis in quadrupoles. The induced dipolar feed down effects reduce the booster horizontal emittance. The same strategy is extended to the ESRF-EBS SR, for an expected emittance reduction of about 20 pm.rad. A first approach shifts the RF frequency by +300 Hz to operate at -1% energy offset. Optimal quadrupole and sextupole settings are defined for this off-energy operation based on simulations. The settings are then tested in the SR in terms of dynamic aperture and injection efficiency.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOTK006  
About • Received ※ 07 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 05 July 2022
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MOPOTK007 Reverse Bend Option for a 6 GeV Storage Ring Lattice emittance, lattice, injection, dynamic-aperture 441
 
  • L. Hoummi, N. Carmignani, L.R. Carver, F. Cianciosi, S.M. Liuzzo, T.P. Perron, S.M. White
    ESRF, Grenoble, France
 
  Several high-energy synchrotron facilities adopted the Hybrid Multi-Bend Achromat scheme (HMBA) developed at and for the ESRF-EBS [LATTICE]. The considered lattice has been developed for a generic 6 GeV storage ring (SR) of 1100m circumference. It includes a short bending (SB) magnet at the center of the cell, and achieves a  ∼ §I{70}{πco\metre\radian} equilibrium horizontal emittance. The optics of such SR are modified introducing reverse bending magnets to further reduce the natural horizontal emittance to §I{53}{πco\metre\radian}. The impact of such modification on dynamic aperture and lifetime is assessed and optimized.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOTK007  
About • Received ※ 20 May 2022 — Revised ※ 10 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 30 June 2022
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MOPOTK008 Options for a Light Upgrade of the ESRF Booster Synchrotron Lattice lattice, booster, quadrupole, extraction 445
 
  • T.P. Perron, N. Carmignani, L.R. Carver, L. Hoummi, S.M. Liuzzo, S.M. White
    ESRF, Grenoble, France
  • P. Raimondi
    SLAC, Menlo Park, California, USA
 
  The EBS 6 GeV electron storage ring recently commissioned at ESRF, in Grenoble, France, is still operated using the old injector hardware. It is now one of the limiting factor of the facility. The large horizontal emittance of the booster beam affects injection efficiency, preventing from reaching 100% transfer efficiency between the 299.8 m long booster and the storage ring. Different lattice modifications going from minor optics changes to full machine renewal are considered . In this paper we will discuss different options of a "light" upgrade of the FODO lattice, keeping the RF system, vacuum chamber, power supplies, and most of the magnets. The upgrade then consists in creating a few new quadrupole families in the straight section vicinity and remove them from the main QF/QD families.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOTK008  
About • Received ※ 05 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 29 June 2022
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MOPOTK018 Parallelization of Radia Magnetostatics Code interface, insertion, insertion-device, synchrotron 481
 
  • A. Banerjee
    SBU, Stony Brook, New York, USA
  • J. Chavanne, G. Le Bec
    ESRF, Grenoble, France
  • O.V. Chubar
    BNL, Upton, New York, USA
  • J.P. Edelen, C.C. Hall, B. Nash
    RadiaSoft LLC, Boulder, Colorado, USA
 
  Funding: Work supported by the US DOE BES SBIR grant No. DE-SC0018556.
Radia 3D magnetostatics code has been used for the design of insertion devices for light sources over more than two decades. The code uses the magnetization integral approach that is efficient for solving permanent magnet and hybrid magnet structures. The initial version of the Radia code was sequential, its core written in C++ and interface in the Mathematica language. This paper describes a new Python-interfaced parallel version of Radia and its applications. The parallelization of the code was implemented on C++ level, following a hybrid approach. Semi-analytical calculations of interaction matrix elements and resultant magnetic fields were parallelized using the Message Passing Interface, whereas the parallelization of the "relaxation" procedure (solving for magnetizations in volumes created by subdivision) was executed using a shared memory method based on C++ multithreading. The parallel performance results are encouraging, particularly for magnetic field calculation post relaxation where a ~600 speedup with respect to sequential execution was obtained. The new parallel Radia version facilitates designs of insertion devices and lattice magnets for novel particle accelerators.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOTK018  
About • Received ※ 20 May 2022 — Revised ※ 10 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 29 June 2022
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MOPOTK051 Modeling a Nb3Sn Cryounit in GPT at UITF cavity, simulation, gun, electron 576
 
  • S. Pokharel, G.A. Krafft
    ODU, Norfolk, Virginia, USA
  • A.S. Hofler, G.A. Krafft
    JLab, Newport News, Virginia, USA
 
  Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
Nb3Sn is a prospective material for future superconducting RF (SRF) accelerator cavities. The material can achieve higher quality factors, higher temperature operation and potentially higher accelerating gradients (Eacc 96 MV/m) compared to conventional niobium. In this work, we performed modeling of the Upgraded Injector Test Facility (UITF) at Jefferson Lab utilizing newly constructed Nb3Sn cavities. We studied the effects of the buncher cavity and varied the gun voltages from 200-500 keV. We have calibrated and optimized the SRF cavity gradients and phases for the Nb3Sn five-cell cavities energy gains with the framework of General Particle Tracer (GPT). Our calculations show the beam goes cleanly through the unit. There is full energy gain out of the second SRF cavity but not from the first SRF cavity due to non-relativistic phase shifts.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOTK051  
About • Received ※ 20 May 2022 — Revised ※ 12 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 19 June 2022
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MOPOTK053 RLAs with FFA Arcs for Protons and Electrons cavity, linac, hadron, optics 584
 
  • V.S. Morozov
    ORNL RAD, Oak Ridge, Tennessee, USA
  • J.F. Benesch, R.M. Bodenstein, S.A. Bogacz, A. Coxe, K.E. Deitrick, D. Douglas, B.R. Gamage, G.A. Krafft, K.E.Price. Price, Y. Roblin, A. Seryi
    JLab, Newport News, Virginia, USA
  • J.S. Berg, S.J. Brooks, F. Méot, D. Trbojevic
    BNL, Upton, New York, USA
  • D. Douglas
    Douglas Consulting, York, Virginia, USA
  • G.H. Hoffstaetter
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Funding: Authored in part by UT-Battelle, LLC, Jefferson Science Associates, LLC, and Brookhaven Science Associates, LLC under Contracts DE-AC05-00OR22725, DE-AC05-06OR23177, and DE-SC0012704 with the US DOE.
Recirculating Linear Accelerators (RLAs) provide an efficient way of producing high-power, high-quality, continuous-wave hadron and lepton beams. However, their attractiveness had been limited by the cumbersomeness of multiple recirculating arcs and by the complexity of the spreader and recombiner regions. The latter problem sets one of the practical limitations on the maximum number of recirculations. We present an RLA design concept where the problem of multiple arcs is solved using the Fixed-Field Alternating gradient (FFA) design as in CBETA. The spreader/recombiner design is greatly simplified using an adiabatic matching approach. It allows for the spreader/recombiner function to be accomplished by a single beam line. The concept is applied to the designs of a high-power hadron accelerator being considered at ORNL and a CEBAF electron energy doubling project, FFA@CEBAF, being developed at Jefferson lab.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOTK053  
About • Received ※ 10 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 21 June 2022
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MOPOTK054 Review of Alignment and Stability Tolerances for Advanced Light Sources alignment, storage-ring, synchrotron, simulation 588
 
  • A. Khan, S.K. Sharma, V.V. Smaluk
    BNL, Upton, New York, USA
 
  Alignment and mechanical-stability specifications are essential to the performance of low-emittance storage rings. Beam dynamics simulations are usually performed to establish these specifications. However, the simulation procedures and the input parameters related to magnet positions are not well established which leads to differences in the final specifications. In this paper we discuss important parameters of the mechanical/structural systems of the storage ring that impact on the alignment and stability specification. Following a detailed review of the specifications and simulation procedures adopted at several facilities we propose a procedure to be used for a low-emittance upgrade of NSLS-II.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOTK054  
About • Received ※ 18 May 2022 — Revised ※ 13 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 07 July 2022
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MOPOTK066 Damping-Ring-Free Injector Design for Linear Colliders emittance, cavity, electron, laser 614
 
  • T. Xu, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  • S.Y. Kim, P. Piot, J.G. Power
    ANL, Lemont, Illinois, USA
  • M. Kuriki
    HU/AdSM, Higashi-Hiroshima, Japan
 
  Funding: This work was supported by the US DOE contracts # DE-SC0018656 and # DE-SC0018234 (U.S.-Japan Science & Technology Cooperation Program in HEP) with NIU and No.DE-AC02-06CH11357 with ANL.
The current designs of future electron-positron linear colliders incorporate large and complex damping rings to produce asymmetric beams for beamstrahlung mitigation at the interaction point. This paper presents the design of an damping-ring-free electron injector capable of delivering flat electron beams with phase-space partition comparable to the electron-beam parameters produced downstream of the damping ring in the proposed international linear collider (ILC) design. The performance of the proposed configuration, its sensitivity to jitter along with its impact on spin-polarization is discussed.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOTK066  
About • Received ※ 07 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 13 June 2022
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TUOXSP2 Analysis of Low RRR SRF Cavities cavity, niobium, accelerating-gradient, radio-frequency 783
 
  • K. Howard, Y.K. Kim
    University of Chicago, Chicago, Illinois, USA
  • D. Bafia, A. Grassellino
    Fermilab, Batavia, Illinois, USA
 
  Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics. This work was supported by the University of Chicago.
Recent findings in the superconducting radio-frequency (SRF) community have shown that introducing certain impurities into high-purity niobium can improve quality factors and accelerating gradients. Success has been found in nitrogen-doping, diffusion of the native oxide into the niobium surface, and thin films of alternate superconductors atop a niobium bulk cavity. We question why some impurities improve RF performance while others hinder it. The purpose of this study is to characterize the impurity profile of niobium with a low residual resistance ratio (RRR) and correlate these impurities with the RF performance of low RRR cavities so that the mechanism of recent impurity-based improvements can be better understood and improved upon. Additionally, we perform a low temperature bake on the low RRR cavity to evaluate how the intentional addition of oxygen to the RF layer affects performance. We have found that low RRR cavities experience low temperature-dependent BCS resistance behavior more prominently than their high RRR counterparts. The results of this study have the potential to unlock a new understanding on SRF materials.
 
slides icon Slides TUOXSP2 [1.495 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUOXSP2  
About • Received ※ 08 June 2022 — Accepted ※ 11 June 2022 — Issue date ※ 25 June 2022  
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TUOZSP3 The European ERL Roadmap electron, gun, FEL, linac 831
 
  • A. Hutton
    JLab, Newport News, Virginia, USA
  • M. Klein
    The University of Liverpool, Liverpool, United Kingdom
  • B.C. Kuske
    HZB, Berlin, Germany
 
  Funding: AH supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under Contract No. DE-AC05-06OR23177
Following the European Strategy process in 2019, five Roadmap Panels were set up to prepare the technologies needed for future accelerators and colliders: high-field magnets, SRF, muon colliders, plasma wakefield accelerators and Energy Recovery Linacs (ERLs). The ERL Roadmap Panel, consisting of ERL experts from around the world, first developed an overview of current and future ERLs. From this it was possible to carry out a gap analysis to see what R&D would be needed, from which the Roadmap could be developed. The European ERL Roadmap focused on three main aspects: 1) the continuation and development of facility programs for which no additional funds are needed, S-DALINAC in Darmstadt and MESA in Mainz; 2) technology development for room-temperature HOM damping and twin-axis SRF cavities; 3) the timely upgrade of bERLinPro for 100 mA current and the construction of PERLE at Orsay as a dedicated 10 MW power multi-turn facility. The roadmap entails a vision of future energy frontier electron-positron and electron-hadron collider and describes a high quality ERL program for 4.4 K SRF technology at high Q0. The presentation will address the ERL Roadmap process and result in detail.
 
slides icon Slides TUOZSP3 [2.868 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUOZSP3  
About • Received ※ 02 June 2022 — Revised ※ 17 June 2022 — Accepted ※ 25 June 2022 — Issue date ※ 29 June 2022
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TUPOST019 Evaluation of PIP-II Master Oscillator Components proton, controls, linac, ISOL 892
 
  • I. Rutkowski, K. Czuba, A. Serlat
    Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
  • B.E. Chase, E. Cullerton
    Fermilab, Batavia, Illinois, USA
 
  Funding: The paper was prepared by WUT and PIP-II, using the resources of Fermilab, a U.S. Department of Energy, Office of Science, HEP User Facility. Fermilab is acting under Contract No. DE-AC02-07CH11359.
The Proton Improvement Plan-II (PIP-II) is a planned proton facility at Fermilab. The short- and long-term beam energy stabilization requirements necessitate using a high-quality Master Oscillator (MO). The consecutive sections of the Linac will operate at 162.5, 325, and 650 MHz. The phase relations between reference signals of harmonic frequencies should be kept constant, and the phase noise should be correlated in a wide bandwidth. The possibility of simultaneously meeting both requirements using popular frequency synthesis schemes is discussed. The ultra-low noise floor of the fundamental source is challenging for other devices in the phase reference distribution system. Therefore, the sensitivity to operating conditions, including impedance matching, input power level, and power supply voltage, must be considered. This paper presents a preliminary performance test of critical components selected for the PIP-II Master Oscillator system performed using a state-of-the-art phase noise analyzer.
The paper was prepared by WUT and PIP-II, using the resources of Fermilab, a U.S. Department of Energy, Office of Science, HEP User Facility. Fermilab is acting under Contract No. DE-AC02-07CH11359.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOST019  
About • Received ※ 08 June 2022 — Revised ※ 16 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 23 June 2022
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TUPOST027 Machine Learning-Based Tuning of Control Parameters for LLRF System of Superconducting Cavities cavity, controls, LLRF, simulation 915
 
  • J.A. Diaz Cruz, S. Biedron
    UNM-ECE, Albuquerque, USA
  • J.A. Diaz Cruz
    SLAC, Menlo Park, California, USA
  • R. Pirayesh
    UNM-ME, Albuquerque, New Mexico, USA
  • S. Sosa
    ODU, Norfolk, Virginia, USA
 
  The multiple systems involved in the operation of particle accelerators use diverse control systems to reach the desired operating point for the machine. Each system needs to tune several control parameters to achieve the required performance. Traditional Low-Level RF (LLRF) systems are implemented as proportional-integral feedback loops, whose gains need to be optimized. In this paper, we explore Machine Learning (ML) as a tool to improve a traditional LLRF controller by tuning its gains using a Neural Network (NN). We present the data production scheme and a control parameter optimization using a NN. The NN training is performed using the THETA supercomputer.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOST027  
About • Received ※ 14 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 20 June 2022
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TUPOPT048 bERLinPro Becomes SEALab: Status and Perspective of the Energy Recovery Linac at HZB linac, electron, cavity, experiment 1110
 
  • A. Neumann, B. Alberdi-Esuain, T. Birke, P. Echevarria, D. Eichel, F. Falkenstern, R. Fleischhauer, A. Frahm, F. Göbel, A. Heugel, F. Hoffmann, H. Huck, T. Kamps, S. Klauke, G. Klemz, J. Kolbe, J. Kühn, B.C. Kuske, J. Kuszynski, S. Mistry, N. Ohm, H. Ploetz, S. Rotterdam, O. Schappeit, G. Schindhelm, C. Schröder, M. Schuster, H. Stein, E. Suljoti, Y. Tamashevich, M. Tannert, J. Ullrich, A. Ushakov, J. Völker, C. Wang
    HZB, Berlin, Germany
  • T. Kamps
    HU Berlin, Berlin, Germany
 
  Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of Helmholtz Association
Since end of the year 2020 the energy recovery linac (ERL) project bERLinPro of Helmholtz-Zentrum Berlin has been officially completed. But what is the status of this facility, the next scientific goals in the framework of accelerator physics at HZB, what are the perspectives? To reflect the continuation of this endeavor and the broadening of applications of this machine from high current SRF based energy recovery concept up to an ultrafast electron diffraction (UED) facility producing shortest electron pulses, the facility is now named Sealab, Superconducting RF Electron Accelerator Laboratory. In this contribution, an overview of lessons learned so far, the status of the machine, the coming set up and commissioning steps with an outlook to midterm and future applications will be given. In summary, Sealab will expand, including the ERL application, and become a general accelerator physics and technology test machine to employ UED as a first study case and will also be an ideal testbed to investigate new control schemes based on digital twins or machine learning methods.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOPT048  
About • Received ※ 06 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 03 July 2022
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TUPOPT062 A Data-Driven Anomaly Detection on SRF Cavities at the European XFEL cavity, FEL, network, experiment 1152
 
  • A. Sulc, A. Eichler, T. Wilksen
    DESY, Hamburg, Germany
 
  Funding: This work was supported by HamburgX grant LFF-HHX-03 to the Center for Data and Computing in Natural Sciences (CDCS) from the Hamburg Ministry of Science, Research, Equalities and Districts.
The European XFEL is currently operating with hundreds of superconducting radio frequency cavities. To be able to minimize the downtimes, prevention of failures on the SRF cavities is crucial. In this paper, we propose an anomaly detection approach based on a neural network model to predict occurrences of breakdowns on the SRF cavities based on a model trained on historical data. We used our existing anomaly detection infrastructure to get a subset of the stored data labeled as faulty. We experimented with different training losses to maximally profit from the available data and trained a recurrent neural network that can predict a failure from a series of pulses. The proposed model is using a tailored architecture with recurrent neural units and takes into account the sequential nature of the problem which can generalize and predict a variety of failures that we have been experiencing in operation.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOPT062  
About • Received ※ 17 May 2022 — Revised ※ 14 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 24 June 2022
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TUPOTK005 Mitigation of Parasitic Losses in the Quadrupole Resonator Enabling Direct Measurements of Low Residual Resistances of SRF Samples niobium, quadrupole, cavity, simulation 1196
 
  • S. Keckert, R. Kleindienst, J. Knobloch, F. Kramer, O. Kugeler, D.B. Tikhonov
    HZB, Berlin, Germany
  • W. Ackermann, H. De Gersem
    TEMF, TU Darmstadt, Darmstadt, Germany
  • X. Jiang, A.O. Sezgin, M. Vogel
    University Siegen, Siegen, Germany
  • J. Knobloch
    University of Siegen, Siegen, Germany
  • M. Wenskat
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
 
  The quadrupole resonator (QPR) is a dedicated sample-test cavity for the RF characterization of superconducting samples in a wide temperature, RF field and frequency range. Its main purpose are high resolution measurements of the surface resistance with direct access to the residual resistance thanks to the low frequency of the first operating quadrupole mode. Besides the well-known high resolution of the QPR, a bias of measurement data towards higher values has been observed, especially at higher harmonic quadrupole modes. Numerical studies show that this can be explained by parasitic RF losses on the adapter flange used to mount samples into the QPR. Coating several micrometer of niobium on those surfaces of the stainless steel flange that are exposed to the RF fields significantly reduced this bias, enabling a direct measurement of a residual resistance smaller than 5 nano-Ohm at 2 K and 413 MHz.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK005  
About • Received ※ 08 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 28 June 2022
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TUPOTK006 Systematic Investigation of Flux Trapping Dynamics in Niobium Samples cavity, experiment, controls, niobium 1200
 
  • F. Kramer, S. Keckert, S. Keckert, J. Knobloch, J. Knobloch, O. Kugeler
    HZB, Berlin, Germany
  • J. Knobloch, O. Kugeler
    BESSY GmbH, Berlin, Germany
  • J. Knobloch
    University of Siegen, Siegen, Germany
 
  Trapped magnetic flux in superconducting cavities can significantly increase surface resistance, and, thereby, limits the cavities’ performance. To reduce trapped flux in cavities, a better understanding of the fundamental mechanism of flux trapping is vital. We develop a new experimental design: measuring magnetic flux density at 15 points just above a niobium sheet of dimensions (100 x 60 x 3) mm with a time resolution of up to 2 ms and a flux resolution better than 0.5 µT. This setup allows us to control the temperature gradient and cooldown rate, both independently of each other, as well as the magnitude and direction of an external magnetic field. We present data gathered on a large-grain sample as well as on a fine-grain sample. Our data suggests that not only the temperature gradient but also the cooldown rate affects trapped flux. Additionally, we detect a non-trivial relationship between trapped flux and magnitude of applied field.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK006  
About • Received ※ 08 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 16 June 2022
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TUPOTK008 Cavity Designs for the Ch3 to Ch11 and Bellow Tuner Investigation of the Superconducting Heavy Ion Accelerator Heliac cavity, heavy-ion, simulation, niobium 1204
 
  • T. Conrad, M. Busch, H. Podlech, M. Schwarz
    IAP, Frankfurt am Main, Germany
  • K. Aulenbacher
    IKP, Mainz, Germany
  • K. Aulenbacher, W.A. Barth, F.D. Dziuba, V. Gettmann, T. Kürzeder, S. Lauber, J. List, M. Miski-Oglu
    HIM, Mainz, Germany
  • W.A. Barth, M. Basten, F.D. Dziuba, M. Heilmann, A. Rubin, A. Schnase, S. Yaramyshev
    GSI, Darmstadt, Germany
 
  New CH-DTL cavities designs of the planned Helmholtz Linear Accelerator (HELIAC) are developed in collaboration of HIM, GSI and IAP Frankfurt. The linac, operated in cw-mode with a final energy of 7.3 MeV/u, is intended for various experiments, in particular with heavy ions at energies close to the Coulomb barrier for research on SHE. Twelve sc CH cavities are foreseen, divided into four different cryostats. Each cavity will be equipped with dynamic bellow tuner. After successful beam tests with CH0, CH3 to CH11 are being designed. Based on the experience gained so far, optimization will be made, which will lead to both an increase in performance in terms of reducing the peak fields limiting superconductivity and a reduction in manufacturing costs and time. In order to optimize manufacturing, attention was paid to design many parts of the cavity, such as lids, spokes, tuner and helium shell, with the same geometrical dimensions. In addition, a tuner test rig was developed, which will be used to investigate the mechanical properties of the bellow tuner. For this purpose, different simulations were made in order to realize conditions as close as possible to reality in the test rig.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK008  
About • Received ※ 08 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 17 June 2022
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TUPOTK010 Nitric Acid Soaking after Imperfect Furnace Treatments cavity, niobium, radio-frequency, linac 1211
 
  • R. Ghanbari, A. Dangwal Pandey
    DESY, Hamburg, Germany
  • C. Bate
    University of Hamburg, Hamburg, Germany
  • W. Hillert, M. Wenskat
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
 
  Annealings of niobium cavities in UHV or nitrogen atmospheres are crucial for the performance in the later cryogenic tests and operation. Recovery methods for imperfect annealing conditions have been discussed, and a more recent proposal, the so-called "nitric acid soak" has been studied here in detail. It shows surprising recovery potential, albeit the unclear origin of this improvement. We present our investigation on the several potential origins. For this, we used SEM, SIMS and XPS measurements of niobium samples to study the surface morphology and contaminations. We can reject the favored hypothesis on the origin of the improvement, and propose an alternative origin.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK010  
About • Received ※ 10 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 18 June 2022
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TUPOTK011 Commissioning of a New Magnetometric Mapping System for SRF Cavity Performance Tests cavity, niobium, ECR, superconducting-cavity 1215
 
  • J.C. Wolff, J. Eschke, A. Gössel, D. Reschke, L. Steder, L. Trelle
    DESY, Hamburg, Germany
  • W. Hillert
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
 
  Funding: This work was supported by the Helmholtz Association within the topic Accelerator Research and Development (ARD) of the Matter and Technologies (MT) Program.
Magnetic flux trapped in the niobium bulk material of superconducting radio frequency (SRF) cavities degrades their quality factor and the accelerating gradient. The sensitivity for flux trapping is mainly determined by the treatment and the geometry of the cavity as well as the niobium grain size and orientation. To potentially improve the flux expulsion characteristics of SRF cavities and hence the efficiency of future accelerator facilities, further studies of the trapping behavior are essential. For this purpose a magnetometric mapping system to monitor the magnetic flux along the outer cavity surface of 1.3 GHz TESLA-Type single-cell SRF cavities has been developed and is currently in the commissioning phase at DESY. Contrary to similar approaches, this system digitizes the sensor signals already inside of the cryostat to extensively reduce the number of required cable feedthroughs. Furthermore, the signal-to-noise ratio (SNR) and consequently the measuring sensitivity can be enhanced by shorter analog signal lines, less thermal noise and the Mu-metal shielding of the cryostat. In this contribution test results gained by a prototype of the mapping system are presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK011  
About • Received ※ 10 June 2022 — Revised ※ 16 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 29 June 2022
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TUPOTK013 PEALD SIS Studies for SRF Cavities cavity, site, plasma, niobium 1222
 
  • I. González Díaz-Palacio, R.H. Blick, A. Stierle, R. Zierold
    University of Hamburg, Hamburg, Germany
  • W. Hillert, M. Wenskat
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • A. Jeromin
    DESY Nanolab, FS-NL, Hamburg, Germany
  • T.F. Keller, N. Krupka, M. Wenskat
    DESY, Hamburg, Germany
 
  Recent technological advances and material treatments have pushed Nb SRF cavities to their maximum RF performance. A novel approach for overcoming this limitation, which takes advantage of RF field only penetrates into the superconductor at a certain distance called London penetration depth, is nano-structuring multilayers with PEALD (plasma-enhanced atomic layer deposition). SIS (superconductor-insulator-superconductor) multilayers provide magnetic screening of the bulk Nb cavity, increasing the field at which the vortex penetration starts, and higher quality factor. ALD is closely related to chemical vapor deposition and bases on sequential self-limit gas-solid surface reactions facilitating conformal coatings with sub-nm precision even on complex substrates such as the interior of a cavity. As a preliminary study for SIS SRF cavities, we investigated the AlN-NbTiN/NbN multilayers grown by PEALD. Different compositions, thicknesses, and post-deposition thermal treatments have been investigated. The characterization results of superconducting properties, elemental composition, crystallinity, and cross-section are shown in this contribution.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK013  
About • Received ※ 09 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 27 June 2022
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TUPOTK014 Refurbishment of SRF Cavities and HOM Antenna Coating Studies for the Mainz Energy-Recovering Superconducting Accelerator (MESA) cavity, cryomodule, HOM, linac 1226
 
  • P.S. Plattner, F. Hug, T. Stengler
    KPH, Mainz, Germany
 
  Funding: The work received funding by BMBF through 05H21UMRB1.
The Mainz Energy-Recovering Superconducting Accelerator (MESA) will be a new recirculating accelerator, which can operate in an external beam mode and an energy recovering mode. In the ERL-mode the electrons cross an internal gas-target at MAGIX and give their kinetic energy into the Superconducting Radio Frequency (SRF) system back after experimental use. The MESA cryomodules are based on ELBE-type cryomodules, which contain two 9-cell TESLA/XFEL-type cavities. For any maintenance the clean room infrastructure at the Helmholtz Institute Mainz (HIM) can be used. Currently, a cryomodule from the decommissioned ALICE ERL at Daresbury, UK is in the process of refurbishment. The refurbishment includes an HPR rinse of the cavities suffering from field emission at present and various adjustments of the module for a future use in MESA, which includes adding piezo tuners and new HOM antennas. For the new antennas, different superconducting coatings (Nb3Sn and NbTiN) will be tested to reach higher critical temperatures in the future for giving the possibility to couple out more HOM power without quenching as the prospected cw beamload lays above 4 mA in MESA ERL operation. Using a superconducting 3 GHz six-cell injector cavity for the S-DALINAC the successful refurbishment of a SRF cavity by applying a high pressure rinse in the clean room infrastructure at HIM was demonstrated the first time.
* The authors acknowledge the transfer of one cryomodule to Mainz by STFC Daresbury.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK014  
About • Received ※ 07 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 18 June 2022 — Issue date ※ 23 June 2022
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TUPOTK016 HiPIMS-Coated Novel S(I)S Multilayers for SRF Cavities cavity, niobium, target, cathode 1234
 
  • A.Ö. Sezgin, X. Jiang, M. Vogel
    University Siegen, Siegen, Germany
  • I. González Díaz-Palacio, R. Zierold
    University of Hamburg, Hamburg, Germany
  • S. Keckert, J. Knobloch, O. Kugeler, D.B. Tikhonov
    HZB, Berlin, Germany
  • J. Knobloch
    University of Siegen, Siegen, Germany
  • R. Ries, E. Seiler
    Slovak Academy of Sciences, Institute of Electrical Engineering, Bratislava, Slovak Republic
 
  Funding: Material syntheses and characterizations via SMART, BMBF, Germany (05K19PSA). Superconducting characterizations via iFAST, H2020, EU (101004730). Part of this work via the MNaF, University of Siegen.
Pushing beyond the existing bulk niobium SRF cavities is indispensable along the path towards obtaining more sustainable next generation compact particle accelerators. One of the promising candidates to push the limits of the bulk niobium is thin film-based multilayer structures in the form of superconductor-insulator-superconductor (SIS). In this work, S(I)S multilayer structures were coated by high power impulse magnetron sputtering (HiPIMS), having industrial upscaling potential along with provid-ing higher quality films with respect to conventional magnetron sputtering techniques (e.g., DCMS), combined with (PE)-ALD techniques for deposition of the ex-situ insulating layers. On the path towards formulating opti-mized recipes for these materials to be coated on the inner walls of (S)RF cavities, the research focuses on innovat-ing the best performing S(I)S multilayer structures con-sisting of alternating superconducting thin films (e.g., NbN) with insulating layers of metal nitrides (e.g., AlN) and/or metal oxides (e.g., AlxOy) on niobium lay-ers/substrates (i.e., Nb/AlN/NbN) in comparison to the so-called SS multilayer structures (i.e., Nb/NbN). This con-tribution presents the initial materials and superconduct-ing and RF characterization results of the aforementioned multilayer systems on flat samples.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK016  
About • Received ※ 11 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 18 June 2022
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TUPOTK018 Combined In-Situ QEXAFS and XRD Investigations on Nb-Treatments in N2 Gas Atmospheres at Elevated Temperatures vacuum, site, cavity, niobium 1238
 
  • P. Rothweiler, F. Eckelt, D. Lützenkirchen-Hecht, S. Paripsa, L. Voß
    University of Wuppertal, Wuppertal, Germany
 
  Funding: We gratefully acknowledge financial support by the German Federal Ministry of Education and Research (BMBF) under project No. 05H18PXRB1.
Thin polycrystalline Nb metal foils were treated in N2 gas atmospheres at elevated temperatures of 900 °C up to 1200 °C. A combination of transmission mode Quick X-ray absorption spectroscopy (QEXAFS) at the Nb-K-edge and X-ray diffraction (XRD) used in parallel were used to investigate changes in the atomic short and long-range structure of the bulk Nb-material in-situ. A dedicated high-vacuum heating cell with a base pressure of 10-6 mbar was used to perform the heat treatments under vacuum and nitrogen gas atmosphere. The treatments typically included (i) a preheating at 900 °C under high-vacuum, (ii) a treatment in 3 mbar nitrogen gas at the desired temperature and (iii) a cooldown to room temperature under vacuum conditions. The QEXAFS and XRD data were collected in parallel during the entire process with a time resolution of 4 s. While the samples treated at 900 °C show the typical N-uptake to the octahedral interstitial sites, the samples treated at higher temperatures show the growth of distinct niobium nitride phases. The results will be discussed in more details during the conference.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK018  
About • Received ※ 08 June 2022 — Revised ※ 09 June 2022 — Accepted ※ 12 June 2022 — Issue date ※ 18 June 2022
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TUPOTK020 Status of LASA-INFN R&D Activity on PIP-II Low-beta Prototypes cavity, radiation, experiment, operation 1241
 
  • M. Bertucci, A. Bosotti, A. D’Ambros, E. Del Core, A.T. Grimaldi, P. Michelato, L. Monaco, C. Pagani, R. Paparella, D. Sertore
    INFN/LASA, Segrate (MI), Italy
  • A. Gresele
    Zanon Research & Innovation, Schio, VI, Italy
  • C. Pagani
    Università degli Studi di Milano & INFN, Segrate, Italy
 
  LASA-INFN is developing some PIP-II β=0.61 cavity prototypes so to set up a high-Q recipe allowing to reach the PIP-II performance target in view of the series production. A single-cell cavity was treated with a XFEL-like baseline recipe, whereas a multicell cavity underwent a mid-T bake step as final surface treatment. Both cavities have been then tested at the LASA vertical experimental facility. The test results are here reported and discussed. Basing on the satisfactory results so far obtained, a strategy for the qualification and upgrade of the LASA vertical test facility is outlined.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK020  
About • Received ※ 08 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 16 June 2022
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TUPOTK021 Recent Update on ESS Medium Beta Cavities at INFN LASA cavity, operation, cryomodule, status 1245
 
  • D. Sertore, M. Bertucci, M. Bonezzi, A. Bosotti, D. Cardelli, A. D’Ambros, A.T. Grimaldi, L. Monaco, R. Paparella, G.M. Zaggia
    INFN/LASA, Segrate (MI), Italy
  • C. Pagani
    Università degli Studi di Milano & INFN, Segrate, Italy
 
  The INFN LASA contribution to the European Spallation Source ERIC (European Research Infrastructure Consortium) Superconducting Linac is focused on supplying 36 cavities for the Medium Beta section of the proton accelerator. Twenty eight cavities have been fully qualified and delivered to CEA for integration into the cryomodules. We present the status of the activities dedicated to completing our contribution both by applying alternative surface treatments with respect to the series vertical BCP and by procuring new cavities.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK021  
About • Received ※ 09 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 25 June 2022  
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TUPOTK022 INFN-LASA for the Fermilab PIP-II cavity, controls, linac, site 1249
 
  • R. Paparella, M. Bertucci, M. Bonezzi, A. Bosotti, D. Cardelli, A. D’Ambros, E. Del Core, A.T. Grimaldi, L. Monaco, D. Sertore, G.M. Zaggia
    INFN/LASA, Segrate (MI), Italy
  • C. Pagani
    Università degli Studi di Milano & INFN, Segrate, Italy
 
  The status of INFN-LASA contribution to the PIP-II project at Fermilab is reported in this paper. Experimental results and ongoing activities on prototypes are summarized together with the development of related testing infrastructures. The series production of the 38 5-cell, beta 0.61 cavities designed by INFN-LASA for the LB650 section of the PIP-II linac recently commenced, the status of major procurements and associated activities is here below presented. All cavities will be produced and surface treated in industry to reach the unprecedented performances required, qualified through vertical cold test at qualified infrastructures and delivered as linac-ready at the string assembly site.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK022  
About • Received ※ 09 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 04 July 2022
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TUPOTK023 Study on Commercial Diodes as Thermometers at Low Temperature for Temperature Mapping System of Nb3sn Superconducting Radiofrequency Cavities experiment, cavity, laser, controls 1252
 
  • R. Wanison, K. Umemori, T. Yamada
    KEK, Ibaraki, Japan
  • K. Takahashi
    Sokendai, Ibaraki, Japan
  • R. Wanison
    Department of Mechanical Engineering, Faculty of Engineering, Chiang Mai University, Chiang Mai, Thailand
 
  Nb3Sn Superconducting radiofrequency (SRF) cavities has been researched and developed at Center for Applied Superconducting Accelerator (CASA), KEK. One of effec-tive tools for research on the performance of SRF cavities is a temperature mapping (T-map) system for detecting small increases in temperature. It is a thermometer array positioned precisely on an outer surface of cavity wall. Thermometer should cover at least from the range of typi-cal operating temperature of 4 K to the transition tempera-ture of 18 K, for the Nb3Sn SRF cavities. Therefore, car-bon resistor can not be used as a cheap thermometer due to low sensitivity at this temperature range. In this pro-ceeding, we report the results of the test for various com-mercially available diodes as a thermometer for T-map system. The sensitivity, stability and the repeatability are measured, cooled by a GM cryocooler.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK023  
About • Received ※ 08 June 2022 — Revised ※ 11 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 07 July 2022
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPOTK027 Field Emission Measurements at Lund Test Stand detector, cavity, cryomodule, shielding 1265
 
  • C.G. Maiano, N. Elias, E. Laface, P. Pierini, L. Sagliano, M.Y. Wang
    ESS, Lund, Sweden
  • E. Cenni
    CEA-IRFU, Gif-sur-Yvette, France
 
  We present here a description of field emission (FE) measurements set-up developed for elliptical cryomodules test activities at Lund Test Stand 2. A test campaign of field emission measurements has been developed and optimized during cryomodules tests. The scintillator detectors (and their respective shields), chosen for these measurements, have been characterized and optimized. The field emission application has been developed and integrated in the cryomodules tests operator interface. The Initial test results are presented and commented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK027  
About • Received ※ 07 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 10 July 2022
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TUPOTK028 Tuning of Superconducting Cavities Using the FFT of Transmitted Power cavity, klystron, resonance, operation 1268
 
  • E. Laface, C.G. Maiano, P. Pierini, M.Y. Wang
    ESS, Lund, Sweden
 
  We implemented a method to tune the ESS superconducting cavities based on the spectral analysis of the high resolution data available from the Low Level RF system (LLRF) for the transmitted power, without the need of connecting a network analyzer or any other dedicated instrumentation along the RF chain. A frequency peak up to 4 MHz off from the resonating frequency can be detected and used to control the stepper motor of the tuner until the cavity is stretched to the proper length to reach the correct operation frequency. Experience of its use at the ESS Test Stand 2 (TS2) facility at Lund during cryomodule acceptance testing is presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK028  
About • Received ※ 16 May 2022 — Revised ※ 11 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 14 June 2022
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TUPOTK031 A First 6 GHz Cavity Deposition with B1 Superconducting Thin Film at ASTeC cavity, target, controls, site 1279
 
  • R. Valizadeh, A.N. Hannah, O.B. Malyshev
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • E. Chyhyrynets, V.A. Garcia Diaz, C. Pira
    INFN/LNL, Legnaro (PD), Italy
  • V.R. Dhanak
    The University of Liverpool, Liverpool, United Kingdom
  • O.B. Malyshev
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • G.B.G. Stenning
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
 
  Nb3Sn, NbTiN and NbN are superconductors with critical temperatures of 18.3, 12.6-17 and 11.6-17.5 K, respectively, these are higher than that of Nb at 9.3 K. Hence, at 4 K, they have an RF resistance, an order of magnitude lower than that of Nb, which leads to quality factors above those of Nb. In recent years, there has been an extensive effort converting Nb cavities into Nb3Sn. Alloying the top inner layer of the cavity using Sn diffusion at a high temperature has had some degree of success, however, the reproducibility remains a major hindering and limiting factor. In this study, we report on the PVD deposition of NbTiN inside a 6 GHz cavity, using an external magnetic coil configuration. The deposition is done at an elevated temperature of about 650 C. We report on the superconducting properties, film structure and its stoichiometry and surface chemical state. The films have been characterised with SEM, XRD, XPS, EDS and SQUID magnetometer.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK031  
About • Received ※ 07 June 2022 — Revised ※ 09 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 06 July 2022
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TUPOTK033 First RF Measurements of Planar SRF Thin Films with a High Throughput Test Facility at Daresbury Laboratory cavity, MMI, site, pick-up 1283
 
  • D.J. Seal, G. Burt, P. Goudket, O.B. Malyshev, B.S. Sian, R. Valizadeh
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • G. Burt, D.J. Seal, B.S. Sian
    Lancaster University, Lancaster, United Kingdom
  • P. Goudket, O.B. Malyshev, R. Valizadeh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • P. Goudket
    ESS, Lund, Sweden
  • H.S. Marks
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
 
  The research on superconducting thin films for future radio frequency (RF) cavities requires measuring the RF properties of these films. However, coating and testing thin films on full-sized cavities is both challenging and timeconsuming. As a result, films are typically deposited on small, flat samples and characterised using a test cavity. At Daresbury Laboratory, a facility for testing 10 cm diameter samples has recently been commissioned. The cavity uses RF chokes to allow physical and thermal separation between itself and the sample under test. The facility allows for surface resistance measurements at a resonant frequency of 7.8 GHz, at temperatures down to 4 K, maximum RF power of 1 W and peak magnetic fields of a few mT. The main advantage of this system is the simple sample mounting procedure due to no physical welding between the sample and test cavity. This allows for a fast turnaround time of two to three days between samples. As such, this system can be used to quickly identify which samples are performing well under RF and should require further testing at higher gradient. Details of recent upgrades to this facility, together with measurements of both bulk niobium and thin film samples, will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK033  
About • Received ※ 08 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 30 June 2022 — Issue date ※ 02 July 2022
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TUPOTK034 Evaluating the Effects of Nitrogen Doping and Oxygen Doping on SRF Cavity Performance cavity, niobium, ECR, simulation 1287
 
  • H. Hu, Y.K. Kim
    University of Chicago, Chicago, Illinois, USA
  • D. Bafia
    Fermilab, Batavia, Illinois, USA
 
  Superconducting radiofrequency (SRF) cavities are resonators with extremely low surface resistance that enable accelerating cavities to have extremely high quality factors (Q0). High Q0 decreases the capital required to keep the accelerators cold by reducing power loss. The performance of SRF cavities is largely governed by the surface composition of the first §I{100}{nm} of the cavity surface. Impurities such as oxygen and nitrogen have been observed to yield high Q0, but their precise roles are still being studied. Here, we compare the performance of cavities doped with nitrogen and oxygen in terms of surface composition and heating behavior with field. A simulation of the diffusion of oxygen into the bulk of the cavity was built using COMSOL Multiphysics software. Simulated results were compared to the actual surface composition of the cavities as determined from secondary ion mass spectrometry analysis. Understanding how these impurities affects performance allows us to have further insight into the underlying mechanisms that enable these surface treatments to yield high Q0.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK034  
About • Received ※ 08 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 12 June 2022 — Issue date ※ 30 June 2022
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TUPOTK035 CVD Nb3Sn-on-Copper SRF Accelerator Cavities cavity, niobium, radio-frequency, factory 1291
 
  • G. Gaitan, P.N. Koufalis, M. Liepe
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • V.M. Arrieta, S.R. McNeal
    Ultramet, Pacoima, California, USA
  • M. Liepe
    Cornell University, Ithaca, New York, USA
 
  Funding: This work is supported by the US Department of Energy SBIR program under grant number DE-SC0017902. Gabriel Gaitan is supported by the National Science Foundation under Grant No. PHY-1549132.
Nb3Sn is the most promising alternative material for achieving superior performance in Superconducting Radio-Frequency (SRF) cavities, compared to conventional bulk Nb cavities now used in accelerators. Chemical vapor deposition (CVD) is an alternative to the vapor diffusion-based Nb3Sn growth technique predominantly used on bulk niobium cavities and may enable reaching superior RF performance at reduced cost. In collaboration with Cornell, Ultramet has developed CVD process capabilities and reactor designs to coat copper SRF cavities with thick and thin films of Nb and Nb3Sn. In this paper, we present our latest research efforts on CVD Nb3Sn-on-copper SRF cavities, including RF performance test results from two 1.3 GHz SRF cavities coated by Ultramet.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK035  
About • Received ※ 15 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 21 June 2022
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TUPOTK036 Study of Chemical Treatments to Optimize Niobium-3 Tin Growth in the Nucleation Phase niobium, cavity, radio-frequency, site 1295
 
  • L. Shpani, S.G. Arnold, G. Gaitan, M. Liepe, Z. Sun
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • T. Arias, M.M. Kelley, N. Sitaraman
    Cornell University, Ithaca, New York, USA
 
  Funding: This research is funded by the National Science Foundation under Grant No. PHY-1549132, the Center for Bright Beams.
Niobium-3 Tin (Nb3Sn) is a high-potential material for next-generation Superconducting Radiofrequency (SRF) cavities in particle accelerators. The most promising growth method to date is based on vapor diffusion of tin into a niobium substrate with nucleating agent Tin Chloride (SnCl2). Still, the current vapor diffusion recipe has significant room for realizing further performance improvement. We are investigating how different chemical treatments on the niobium substrate before coating influence the growth of a smooth and uniform Nb3Sn layer. More specifically, this study focuses on the interaction between the SnCl2 nucleating agent and the niobium surface oxides. We compare the effect of different chemical treatments with different pH values on the tin droplet distribution on niobium after the nucleation stage of coating. We also look at the effect that the nucleation temperature has on the smoothness and uniformity of the tin distribution, with the ultimate goal of optimizing the recipe to coat smooth Nb3Sn cavities.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK036  
About • Received ※ 12 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 17 June 2022
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TUPOTK037 Status Update on Cornell’s SRF Compact Conduction Cooled Cryomodule cavity, cryomodule, operation, radio-frequency 1299
 
  • N.A. Stilin, A.T. Holic, M. Liepe, T.I. O’Connell, J. Sears, V.D. Shemelin, J. Turco
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  A new frontier in Superconducting RF (SRF) development is increasing the accessibility of SRF technology to small-scale accelerator operations which are used in various industrial or research applications. This is made possible by using commercial cryocoolers as a cooling source, which removes the need for expensive liquid cryogenics and their supporting infrastructure. Cornell University is currently developing a new cryomodule based on a conduction cooling scheme. This cryomodule will use two pulse tube cryocoolers in place of liquid cryogenics in order to cool the system. A new 1.3 GHz cavity has been designed with a set of four niobium rings welded at the equator and irises which allow for a direct thermal link between the cavity and cryocooler cold heads. The cavity will use two coaxial RF input couplers capable of delivering up to 100 kW total RF power for high-current beam operation. This coupler design was modified from the Cornell ERL injector couplers, including simplifications such as removing the cold RF window and most outer bellows, while retaining inner bellows for adjustable coupling.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK037  
About • Received ※ 12 June 2022 — Revised ※ 11 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 16 June 2022
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TUPOTK038 Next Generation SRF Cavities at Cornell University cavity, simulation, radio-frequency, accelerating-gradient 1303
 
  • N.M. Verboncoeur, M. Liepe, R.D. Porter, L. Shpani
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Our goal is to develop new materials and protocols for the growth and preparation of thin-film and layered superconductors for next generation SRF cavities with higher performance for future accelerators. We are working primarily with Nb3Sn to achieve this goal, as well as other materials which aim to optimize the RF field penetration layer of the cavity. This contribution gives a general update on our most recent cavity test results. A deeper insight into RF loss distribution and dynamics during cavity testing is gained using a new global high-speed temperature mapping system (T-Map).  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK038  
About • Received ※ 11 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 22 June 2022
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TUPOTK042 Challenges to Reliable Production Nitrogen Doping of Nb for SRF Accelerating Cavities cavity, niobium, vacuum, controls 1311
 
  • C.E. Reece, M.J. Kelley, E.M. Lechner, A.D. Palczewski
    JLab, Newport News, Virginia, USA
  • J.W. Angle, M.J. Kelley
    Virginia Polytechnic Institute and State University, Blacksburg, USA
  • F.A. Stevie
    NCSU AIF, Raleigh, North Carolina, USA
 
  Funding: This work was authored by JSA LLC under U.S. DOE contract DE-AC05-06OR23177. This material is based on work supported by the U.S. DOE Early Career Award to A. Palczewski, with supplemental support from DOE BES via the LCLS-II HE R&D program. J. Angle’s support was from the Office of High Energy Physics, under grant DE-SC-0014475 to Virginia Tech.
Over the last several years, alloying of the surface layer of niobium SRF cavities has been demonstrated to beneficially lower the superconducting RF surface resistance. Nitrogen, titanium, and oxygen have all been demonstrated as effective alloying agents, occupying interstitial sites in the niobium lattice within the RF penetration depth and even deeper, when allowed to thermally diffuse into the surface at appropriate temperatures. The use of nitrogen for this function has been often termed ’nitrogen doping’ and is being applied in the LCLS-II and LCLS-II HE projects. We report characterization studies of the distribution of nitrogen into the exposed niobium surface and how such distribution is affected by the quality of the vacuum furnace environment in which the doping takes place, and the complexity of nitride crystal growth on different grain orientations of surface niobium. Using state-of-the-art quantification methods by dynamic secondary ion mass spectrometry (SIMS) depth profiling in niobium, we identify several phenomena involving furnace-sourced contamination. We also highlight a potential issue with N2 flow constraints from the flange ’caps’ used during heat treatments.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK042  
About • Received ※ 07 June 2022 — Revised ※ 09 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 05 July 2022
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TUPOTK044 Preliminary Results of a Magnetic and Temperature Map System for 3 GHz Superconducting Radio Frequency Cavities cavity, MMI, radio-frequency, niobium 1315
 
  • I.P. Parajuli, G. Ciovati, J.R. Delayen, A.V. Gurevich, B.D. Khanal
    ODU, Norfolk, Virginia, USA
  • G. Ciovati, J.R. Delayen
    JLab, Newport News, Virginia, USA
 
  Funding: Work supported by NSF Grant 100614-010. Jlab work is supported by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Superconducting radio frequency (SRF) cavities are fundamental building blocks of modern particle accelerators. A surface resistance in the tens of nanoOhm range is achieved when cooling these cavities to liquid helium temperature, ~2 - 4 K. One of the leading sources of residual losses in SRF cavities is trapped magnetic flux. Flux trapping mechanism depends on different surface preparations and cool-down conditions. We have designed, developed and commissioned a combined magnetic and temperature mapping system using anisotropic magneto-resistance sensors and carbon resistors, respectively, to study the flux trap mechanism in 3 GHz single-cell niobium cavities. In this contribution, we will describe the experimental apparatus and present preliminary test results.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK044  
About • Received ※ 02 June 2022 — Revised ※ 11 June 2022 — Accepted ※ 24 June 2022 — Issue date ※ 25 June 2022
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TUPOTK045 Magnetic Field Mapping of 1.3 GHz Superconducting Radio Frequency Niobium Cavities cavity, niobium, MMI, radio-frequency 1319
 
  • I.P. Parajuli, G. Ciovati, J.R. Delayen, A.V. Gurevich
    ODU, Norfolk, Virginia, USA
  • G. Ciovati, J.R. Delayen
    JLab, Newport News, Virginia, USA
 
  Funding: Work supported by NSF Grant 100614-010. Jlab work is supported by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Niobium is the material of choice to build superconducting radio frequency (SRF) cavities, which are fundamental building blocks of modern particle accelerators. These cavities require a cryogenic cool-down to ~2 - 4 K for optimum performance minimizing RF losses on the inner cavity surface. However, temperature-independent residual losses in SRF cavities cannot be prevented entirely. One of the significant contributor to residual losses is trapped magnetic flux. The flux trapping mechanism depends on different factors, such as surface preparations and cool-down conditions. We have developed a diagnostic magnetic field scanning system (MFSS) using Hall probes and anisotropic magneto-resistance sensors to study the spatial distribution of trapped flux in 1.3 GHz single-cell cavities. The first result from this newly commissioned system revealed that the trapped flux on the cavity surface might redistribute with increasing RF power. The MFSS was also able to capture significant magnetic field enhancement at specific cavity locations after a quench.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK045  
About • Received ※ 02 June 2022 — Revised ※ 09 June 2022 — Accepted ※ 20 June 2022 — Issue date ※ 27 June 2022
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TUPOTK054 Solid State Amplifiers for Beam Test System of PAPS at IHEP superconducting-cavity, cavity, operation, status 1342
 
  • O. Xiao, Y.L. Chi, N. Gan, X.P. Li, Z.D. Zhang
    IHEP, People’s Republic of China
 
  Solid state amplifiers are being increasingly used as RF power sources in accelerators around the world. Two solid state amplifiers with different output power and frequen-cy have been applied in beam test system of PAPS at IHEP. A 10kW solid state amplifier operating at 1.3 GHz is used to feed a normal conducting buncher. A 650 MHz solid state amplifier with the output power of 150 kW is used to feed two 2-cell superconducting cavities. So far, the debugging and acceptance test of solid state amplifi-ers have been finished. During the beam test system commissioning and operation, all solid state amplifiers operate stably. In this paper, the specifications and high power test results of solid state amplifiers are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK054  
About • Received ※ 19 May 2022 — Revised ※ 10 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 06 July 2022
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TUPOTK057 Innovative Magnetron Power Sources for Superconducting RF (SRF) Accelerators controls, cavity, operation, injection 1348
 
  • M.L. Neubauer, R.P. Johnson, R.R. Lentz, M. Popovic, T. Wynn
    Muons, Inc, Illinois, USA
  • R.A. Rimmer, H. Wang
    JLab, Newport News, Virginia, USA
 
  Funding: Work supported by DOE SBIR grant # DE-SC0022484
A magnetron suitable for 1497 MHz klystron replacements at Jefferson Lab will be constructed and tested with our novel patented subcritical voltage operation methods to drive an SRF cavity. The critical areas of magnetron manufacturing and design affecting life-cycle costs that will be modeled for improvement include: Qext, filaments, magnetic field, vane design, and novel control of outgassing. The most immediate benefit of this project is to make SRF accelerator projects more affordable for NP and other users of SRF Linacs. One of the most attractive commercial applications for SRF accelerators is to drive subcritical nuclear reactors to burn Light Water Reactor Spent Nuclear Fuel (LWR SNF). A 1 GeV proton beam hitting an internal uranium spallation neutron target can produce over 30 neutrons for each incident proton to allow the reactor to operate far below criticality to generate electricity or process heat while reducing high-level waste disposal costs. This commercial application has the additional attribute of addressing climate change.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK057  
About • Received ※ 09 June 2022 — Revised ※ 11 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 09 July 2022
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TUPOTK059 Modeling O and N Alloying in Nb for SRF Applications cavity, niobium, radio-frequency, vacuum 1354
 
  • E.M. Lechner, M.J. Kelley, A.D. Palczewski, C.E. Reece
    JLab, Newport News, Virginia, USA
  • J.W. Angle, M.J. Kelley
    Virginia Polytechnic Institute and State University, Blacksburg, USA
  • F.A. Stevie
    NCSU AIF, Raleigh, North Carolina, USA
 
  Funding: This work was coauthored by Jefferson Science Associates LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and grant No. DE-SC-0014475 to Virginia Tech for the support of J. Angle.
N and O-alloyed superconducting radio frequency cavities exhibit extraordinary quality factors. Developing diffusion models that describe interstitial N and O in Nb is important for optimizing alloyed cavity quality factors and accelerating gradients. N and O-alloyed Nb samples are examined with SEM AND SIMS and their diffusion profiles modeled.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK059  
About • Received ※ 08 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 17 June 2022
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TUPOMS006 FILO: A New Application to Correct Optics in the ESRF-EBS Storage Ring optics, quadrupole, lattice, operation 1401
 
  • S.M. Liuzzo, N. Carmignani, L.R. Carver, L. Farvacque, L. Hoummi, T.P. Perron, B. Roche, B. Vedder, S.M. White
    ESRF, Grenoble, France
 
  A new optics correction application (Fit and Improvement of Linear Optics, FILO) was designed and set in place for the ESRF-EBS storage ring. The widely used software LOCO* is not available at ESRF and despite a few trials to set it in operation, it has been decided to write a new code. The application is flexible, may be used via the control system simulators and is adapted to a user friendly operation thanks to a wizard mode. Some features of LOCO are copied over, some others are yet to be implemented. The measurement of on and off-energy response matrices using slow or fast steerers is integrated in the same application. Results obtained with this application are presented together with an overview of the future developments.
*J Safranek, Experimental determination of storage ring optics using orbit response measurements, https://doi.org/10.1016/S0168-9002(97)00309-4
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOMS006  
About • Received ※ 19 May 2022 — Revised ※ 10 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 15 June 2022
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TUPOMS007 A Long Booster Option for the ESRF-EBS 6 GeV Storage Ring booster, injection, lattice, storage-ring 1405
 
  • S.M. Liuzzo, N. Carmignani, L.R. Carver, L. Hoummi, T.P. Perron, S.M. White
    ESRF, Grenoble, France
 
  Despite the several fruitful upgrades undergone, the present injector complex of the ESRF-EBS has a rather large horizontal natural emittance at extraction of >60nmrad. Several light sources (SLS, ALBA, SIRIUS) have adopted booster injectors fitting in the same tunnel as the main SR. The study of such an injector is shown in this paper for the ESRF-EBS. The proposed solution is based on a DBA lattice structure with 5 quadrupole families and 2 sextupole families. The possibility to install this long booster on the internal wall of the ESRF storage ring tunnel is assessed and the adequate distances are analyzed. The possibility to keep the existing injector is also considered in order to use this additional ring as an accumulator ring. Injection and extraction schemes are described.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOMS007  
About • Received ※ 19 May 2022 — Revised ※ 09 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 14 June 2022
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TUPOMS009 First Year of Operation of the ESRF-EBS Ligth Source operation, injection, emittance, cavity 1413
 
  • J.-L. Revol, C. Benabderrahmane, P.B. Borowiec, E. Buratin, N. Carmignani, L.R. Carver, A. D’Elia, M. Dubrulle, F. Ewald, A. Franchi, G. Gautier, L. Hardy, L. Hoummi, J. Jacob, L. Jolly, G. Le Bec, I. Leconte, S.M. Liuzzo, M. Morati, T.P. Perron, Q. Qin, B. Roche, K.B. Scheidt, V. Serrière, R. Versteegen, S.M. White
    ESRF, Grenoble, France
 
  The European Synchrotron Radiation Facility - Extremely Brilliant Source (ESRF-EBS) is a facility upgrade allowing its scientific users to take advantage of the first high-energy 4th generation light source. In December 2018, after 30 years of operation, the beam stopped for a 12-month shutdown to dismantle the old storage ring and to install the new X-ray source. On 25 August 2020, the user programme was restarted with beam parameters very close to nominal values. This paper reports on the present operation performance of the source, highlighting the ongoing and planned development.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOMS009  
About • Received ※ 08 June 2022 — Revised ※ 16 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 06 July 2022
Cite • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPOTK060 Prospects of Ultrafast Electron Diffraction Experiments at Sealab electron, experiment, cavity, gun 2201
 
  • B. Alberdi-Esuain, J.-G. Hwang, T. Kamps, A. Neumann, J. Völker
    HZB, Berlin, Germany
  • T. Kamps
    HU Berlin, Berlin, Germany
 
  Ultrafast Electron Diffraction (UED) is a pump-probe experimental technique that aims to image the structural changes that happen in a target structure due to photo-excitation. Development of MeV UED capabilities is one of the main objectives at Sealab, a superconducting RF accelerator facility being commissioned in Helmholtz-Zentrum Berlin. In order to perform UED experiments, the optimization of temporal resolution is of the utmost importance. The composition of the SRF Photoinjector, currently the main beam-line in Sealab, offers superb flexibility to manipulate the longitudinal phase-space of the electron bunch. At the same time, the CW operation of the accelerator provides an enhanced beam stability compared to warm guns, together with MHz repetition rates. This work aims to show the capacity of the SRF Photoinjector in Sealab to reach the required temporal resolution and explain the development and current status of the necessary tools to perform UED experiments at the facility.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK060  
About • Received ※ 08 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 03 July 2022  
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WEPOMS003 Beam Dynamics with a Superconducting Harmonic Cavity for the SOLEIL Upgrade cavity, simulation, synchrotron, operation 2229
 
  • A. Gamelin, W. Foosang, P. Marchand, R. Nagaoka
    SOLEIL, Gif-sur-Yvette, France
  • N. Yamamoto
    KEK, Ibaraki, Japan
 
  In 4th generation low emittance synchrotron light sources, harmonic cavities are critical components needed to reach the required performance. However, RF systems with harmonic cavities can be limited by their own set of instabilities. An instability dominated by the coupled-bunch mode l=1 can prevent the RF system from reaching the flat potential condition, hence limiting the maximum bunch lengthening. Here we report how this instability impacts the performance of 3rd and 4th harmonic superconducting cavities for the SOLEIL Upgrade.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS003  
About • Received ※ 08 June 2022 — Accepted ※ 22 June 2022 — Issue date ※ 26 June 2022  
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THPOST025 Operational Experience with the Improved VSR DEMO Collimating Shielded Bellow in BESSY II operation, cavity, vacuum, synchrotron 2497
 
  • H.-W. Glock, V. Dürr, F. Glöckner, J. Knobloch, M. Ries, A. Vélez
    HZB, Berlin, Germany
  • J. Knobloch
    University of Siegen, Siegen, Germany
  • A. Vélez
    Technical University Dortmund, Dortmund, Germany
 
  Funding: Work supported by grants of the Helmholtz Association
The Collimating Shielded Bellow (CsB) is designed to serve both as a flexible beam pipe connection between two adjacent superconducting cavities as foreseen in VSR DEMO and as a synchrotron light collimator to shield the down-stream cavity from synchrotron radiation. A convoluted inner RF shield was applied to prevent fundamental mode heating of the stainless-steel-made bellow in the cryogenic environment, making the such captured inner volume very difficult to access for inspection and cleaning. A first version of the device was successfully tested as part of the beam pipe of the synchrotron light source BESSY II under regular operation for more than a year. It suffered from an unfavorable long outgassing commissioning. Therefore a detachable design, allowing for rigorous inner surface preparation and cleaning, was built and recently installed in BESSY II. CsB version 2 design and experimental outcomes are described in the paper. First results indicated a significantly improved vacuum commissioning performance, which was confirmed later on.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOST025  
About • Received ※ 14 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 10 July 2022  
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THPOST026 Design of the Magnetic Shield for VSR DEMO cavity, simulation, shielding, GUI 2501
 
  • H.-W. Glock, P. Anumula, F. Glöckner, J. Knobloch, F. Pflocksch, A. Vélez
    HZB, Berlin, Germany
  • J. Knobloch
    University of Siegen, Siegen, Germany
  • A. Vélez
    Technical University Dortmund, Dortmund, Germany
 
  Funding: Work supported by grants of the Helmholtz Association
The VSR DEMO module, recently under development at HZB, will house two 4-cell 1.5 GHz superconducting RF cavities with a particularly powerful HOM damping scheme based on five waveguide HOM absorbers per cavity. A magnetic shield made of high-permeable material is needed around the cavities in order to prevent the ambient magnetic field exceeding very few µT thereby causing considerable unwanted RF losses. The shield needs to accommodate the waveguides, the fundamental power coupler, two beam pipes, two He feed / return lines, the tuner and the support structures, whilst being manufacturable and mountable. The paper discusses those difficulties and presents the matured magnetic shield design. Numerical simulations are used to evaluate the efficacy of the shield.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOST026  
About • Received ※ 14 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 22 June 2022 — Issue date ※ 22 June 2022
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THPOST038 On-Site Transport and Handling Tests of Cryomodules for the European Spallation Source cryomodule, cavity, site, diagnostics 2527
 
  • F. Schlander, A. Bignami, N. Gazis
    ESS, Lund, Sweden
 
  The cryomodules for the superconducting Linac of the European Spallation Source ’ ESS are now arriving in a steady stream and the long-distance transport requirements are well understood. For the on-site transportation, handling and storage, several challenges have risen, including the intermediate storage of cryomodules before testing and/or installation. In comparison to the long-distance transports, the cryomodule on-site transports and respective handling until installation take place with specialised and limited transport protection. This requires additional measures and tests of those handling steps with extended diagnostics, to make sure that handling and transport refrains from damages on the last mile. Those handling procedures and executed tests will be described in this contribution.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOST038  
About • Received ※ 07 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 25 June 2022
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THPOPT001 Online Optimization of the ESRF-EBS Storage Ring Lifetime sextupole, octupole, lattice, simulation 2552
 
  • N. Carmignani, L.R. Carver, L. Hoummi, S.M. Liuzzo, T.P. Perron, P. Raimondi, S.M. White
    ESRF, Grenoble, France
 
  In the first year of operation of the EBS storage ring, online nonlinear dynamics optimisations were performed to increase the Touschek lifetime. Several sextupole, octupole and skew quadrupole knobs have been studied in simulations and tested in the machine. A fast optimisation procedure has been defined and it is followed at each machine restart. The knobs and the optimisation procedure are described in the paper. As a result, up to 41 h Touschek lifetime in nominal multi-bunch mode have been achieved.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT001  
About • Received ※ 07 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 21 June 2022
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THPOPT002 Beam Power Deposition on the Cryogenic Permanent Magnet Undulator simulation, cryogenics, undulator, impedance 2556
 
  • L.R. Carver, C. Benabderrahmane, P. Brumund, N. Carmignani, J. Chavanne, G. Le Bec, R. Versteegen, S.M. White
    ESRF, Grenoble, France
 
  X-rays with high brilliance and low phase errors are generated in the Cryogenic Permanent Magnet Undulator (CPMU) currently in use at the ESRF. In the event of a failure of the cryogenic cooling the beam will continue to deposit power into the module, even when the undulator jaws are fully opened. This could lead to unacceptably high heating of the magnet blocks which could cause their demagnetisation. Impedance simulations were performed using IW2D and CST to compute the power deposited by the beam in both the closed and open jaw settings. This was followed by thermal simulations to compute the expected temperature rise. These results will help advise the operational procedure in the event of a cooling failure.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT002  
About • Received ※ 07 June 2022 — Revised ※ 09 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 27 June 2022
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THPOPT019 Multi-Alkali Antimonide Photocathode Development for High Brightness Beams cathode, brightness, gun, electron 2610
 
  • S. Mistry, T. Kamps, J. Kühn, C. Wang
    HZB, Berlin, Germany
  • T. Kamps
    HU Berlin, Berlin, Germany
  • C. Wang
    University Siegen, Siegen, Germany
 
  Funding: This work is funded by the DFG CO 1509/10-1 | MI 2917/1-1
Photocathode R&D at the Helmholtz-Zentrum Berlin (HZB) is driven by the motivation to produce high brightness electron beams for the SRF photoinjector test facility, Sealab/ bERLinPro. Multi-alkali antimonides are the choice photocathode material due to high quantum efficiency (QE) and low intrinsic emittance in the visible range. In this work a more robust alternative to the tried and tested Cs-K-Sb is considered. Na-K-Sb offers similar advantages to Cs-K-Sb including, high QE at green wavelengths but moreover, it offers excellent stability at elevated temperatures. This property could lengthen the cathode lifetime by enhancing the robustness of the photocathode inside the SRF gun. In this work, a status report showcasing first results towards the development of a growth procedure for Na-K-Sb is presented by means of spectral response and XPS measurements conducted in the HZB photocathode lab.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT019  
About • Received ※ 03 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 04 July 2022
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THPOPT022 Study on QE Evolution of Cs2Te Photocathodes in ELBE SRF Gun-II cathode, gun, operation, vacuum 2617
 
  • R. Xiang, A. Arnold, S. Ma, P. Michel, P. Murcek, A.A. Ryzhov, J. Schaber, J. Teichert, P.Z. Zwartek
    HZDR, Dresden, Germany
 
  The quality of the photocathodes is critical for the sta-bility and reliability of the photoinjector’s operation. Thanks to the robust magnesium and Cs2Te photocathodes, SRF gun-II at HZDR has been proven to be a suc-cessful example in CW mode for high current user operation. In this contribution, we will present our observation of the QE evolution of Cs2Te photocathodes during SRF gun operation. The variables including substrate surface, film thickness, Cs/Te stoichiometric, multipacting, RF loading and charge extract are considered in the analysis.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT022  
About • Received ※ 07 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 06 July 2022
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THPOPT040 Injection Using a Non-Linear Kicker at the ESRF injection, kicker, simulation, emittance 2679
 
  • S.M. White, T.P. Perron
    ESRF, Grenoble, France
 
  The ESRF injection consists in a standard four kickers bump off-axis injection. Although this scheme is very robust and reliable it is known to disturb users during injections and may represent a severe limitation in case frequent injections are required. The non-linear kicker injection scheme provides a possible solution to this problem by acting only on the injected beam. This paper reports on the potential integration of a non-linear kicker injection scheme at the ESRF. A layout and specifications for the kicker are proposed and simulations are provided to evaluate the performance and limitations of such scheme.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT040  
About • Received ※ 07 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 01 July 2022
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THPOPT041 Commissioning of New Kicker Power Supplies to Improve Injection Perturbations at the ESRF injection, power-supply, kicker, storage-ring 2683
 
  • S.M. White, N. Carmignani, L.R. Carver, M. Dubrulle, L. Hoummi, M. Morati, T.P. Perron, B. Roche
    ESRF, Grenoble, France
 
  The ESRF-EBS storage ring resumed operation in 2020. Due to the reduced lifetime, top-up injection is required for all operation modes. Perturbations on the stored beam introduced by the pulsed injection elements represent a significant disturbance to the beam lines that need to run experiments across injection. In order to reduce these perturbation, new kicker power supplies with slower ramping times and better shot-to-shot reproducibility were developed at ESRF to improve the efficiency of the feed-forward compensation scheme. This paper reports on the design, commissioning and first experimental validation of these new power supplies.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT041  
About • Received ※ 07 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 01 July 2022
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THPOPT050 Development and Construction of Cryogenic Permanent Magnet Undulators for ESRF-EBS undulator, permanent-magnet, vacuum, cryogenics 2712
 
  • C. Benabderrahmane, P. Brumund, J. Chavanne, D. Coulon, G. Le Bec, B. Ogier, R. Versteegen
    ESRF, Grenoble, France
 
  The ESRF Extremely Brilliant Source (ESRF-EBS) is on operation for Users since August 2020 after 20 months of shutdown. This first of a kind fourth generation high energy synchrotron is based on a Hybrid Multi-Bend Achromat lattice. The main goal of the ESRF-EBS is to reduce the horizontal emittance, which leads to a signifi-cant increase of the X-ray source brilliance. To cover the intensive demand of short period small gap undulators at ESRF-EBS, a new design for a 2 m Cryogenic Permanent Magnet Undulator (CPMU) has been developed. Six CPMUs will be installed in the next years; the first two CPMUs have been constructed and actually used on ID15 and ID16 beamline, the third one is under con-structing. An intensive refurbishment work has been done on the existing insertion devices to adapt them to the new accelerator which has shorter straight section and closer dipoles to the IDs than in the old one. This contribution will review the development, construc-tion and commissioning of the new CPMUs, and the refurbishment work done on the existing ones to adapt them to the new accelerator.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT050  
About • Received ※ 02 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 18 June 2022
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THPOTK022 Cryogenic Infrastructure for the Mainz Energy-Recovering Superconducting Accelerator (MESA) cryogenics, experiment, target, cryomodule 2813
 
  • T. Stengler, K. Aulenbacher, F. Hug, P.S. Plattner, D. Simon
    KPH, Mainz, Germany
 
  Funding: Work supported by the German Research Foundation (DFG) under the Cluster of Excellence "PRISMA+" EXC 2118/2019
The "Mainz Energy-Recovering Superconducting Accelerator" (MESA), currently under construction at the Institute of Nuclear Physics, Johannes Gutenberg University Mainz, Germany, requires a cryogenic infrastructure for its superconducting components. Prior to the start of the project, a helium liquefier was purchased that is capable of supplying the existing infrastructure of the Institute for Nuclear Physics, as well as the SRF test facility of the Helmholtz Institute. The liquefier has already been purchased in such a way that nitrogen pre-cooling can be integrated and can be upgraded for the operation of MESA. In addition to the superconducting accelerator modules, all components of the P2 experiment, i.e. solenoid, target and polarimeter (hydromoller), must also be supplied with liquid helium. Therefore, besides the upgrade of the liquefier, it is necessary to extend the system with a dedicated cryogenic supply for the P2 target. This paper presents the current status of the cryogenic supply of the MESA accelerator, the future modifications and additions.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOTK022  
About • Received ※ 07 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 06 July 2022
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THPOTK025 Heat Loads Measurement Methods for the ESS Elliptical Cryomodules SAT at Lund Test Stand cavity, cryogenics, cryomodule, ECR 2819
 
  • N. Elias, X.T. Su
    ESS, Lund, Sweden
  • W. Gaj, P. Halczynski, M. Sienkiewicz, F.D. Skalka
    IFJ-PAN, Kraków, Poland
 
  The Site Acceptance Testing of all ESS elliptical cryomodules is done at Lund Test Stand. The cryogenic heat loads (static and dynamic) are an essential part of the acceptance criteria. We present complementary measurement methods for evaluating the cryogenic heat loads and discuss a qualitative comparison between them. We also present a summary of the results of these methods for one of the cryomodules.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-THPOTK025  
About • Received ※ 07 June 2022 — Revised ※ 13 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 10 July 2022
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