TUP —  Tuesday Poster Session   (02-Jul-19   14:30—18:00)
Paper Title Page
TUP002 Modeling of Superconducting Spoke Cavity with its Control Loops Systems for the MYRRHA Linac Project -1
 
  • M. Dominiczak
    ACS, Orsay, France
  • F. Bouly
    LPSC, Grenoble Cedex, France
  • N. Gandolfo, C. Joly
    IPN, Orsay, France
 
  In the construction framework of a future 600 MeV/4 mA CW Superconducting Linac accelerator for the MYRRHA project at SCK’CEN (Mol, Belgium), modeling works under Matlab/Simulink are carried out upstream to understand the behaviour of 352 MHz single Spoke cavity with its environment and its associated feedback control loops (LLRF and cold tuning system). One of the main goal is to assess the feasibility of cavity failure compensation in the Superconducting Linac. Indeed, stringent reliability requirements must be fulfilled to ensure an efficient operation of the MYRRHA Accelerator Driven System: unexpected beam interruptions, due to failures, must be compensated in less than 3 seconds. Our preliminary study focuses on the fast frequency re-tuning of the cavity and the power balances. Our goal is to prepare the R&D tests foreseen at IPN Orsay on a prototype cryomodule including two SC Spoke cavities equipped with couplers, tuners with feedback loop and connected to dedicate LLRF.
Nicolas Gandolfo, IPNO, Orsay (France)
Christophe Joly, IPNO, Orsay (France)
Frédéric Bouly, LPSC, Grenoble (France)
 
 
TUP003
Design of a Multimodal Quadripole Resonator for Thin Films Characterization  
 
  • S. Bira, S. Blivet, P. Duchesne, D. Longuevergne, G. Martinet, G. Olry
    IPN, Orsay, France
 
  Nowadays, most of superconducting cavities are made of bulk Niobium. The high quality of today’s surface processes allows us to reach accelerating gradient very close to Niobium limit. New materials such as Nb3Sn, NbN and MgB2, showing higher critical temperature and magnetic field must be investigated to improve acceleration capabilities. As these materials could only be used as thin films, the tuning and optimization of the deposition processes require to be performed on small and flat samples. In that sense, it is necessary to perform cryogenic RF tests directly on these flat samples. These tests have to be realized with high resolution measurements of surface resistance in a large range of magnetic field and operating temperature. In order to perform these measurements, a quadrupole resonator has been designed at the Institute of Nuclear Physics of Orsay, France. It is based on the quadrupole resonator developed at CERN. However, it allows to characterize smaller disks of 20 mm in diameter. Regarding the size of the sample, the resonator has been tuned to operate at 1.3 GHz. Higher harmonics such as 2.6 GHz and 3.9 GHz can also be excited  
 
TUP004 Latest Cryogenic Test Results of the Superconducting β=0.069 CH-cavities for the HELIAC-project -1
 
  • M. Basten, M. Busch, T. Conrad, H. Podlech, M. Schwarz
    IAP, Frankfurt am Main, Germany
  • K. Aulenbacher, W.A. Barth, C. Burandt, F.D. Dziuba, V. Gettmann, M. Heilmann, T. Kürzeder, S. Lauber, J. List, M. Miski-Oglu, J. Salvatore, A. Schnase, S. Yaramyshev
    GSI, Darmstadt, Germany
  • K. Aulenbacher, W.A. Barth, C. Burandt, F.D. Dziuba, V. Gettmann, T. Kürzeder, S. Lauber, J. List, M. Miski-Oglu
    HIM, Mainz, Germany
  • K. Aulenbacher, S. Lauber
    IKP, Mainz, Germany
  • F.D. Dziuba, J. List
    KPH, Mainz, Germany
 
  The upcoming FAIR (Facility for Antiproton and Ion Research) project at GSI will use the existing UNILAC (UNIversal Linear Accelerator) as an injector, reducing the beam time for the ambitious Super Heavy Element (SHE) program. To keep the UNILAC user program competitive a new superconducting (sc) continuous wave (cw) high intensity heavy ion LINAC should provide ion beams with max. duty factor above the coulomb barrier. The fundamental sc LINAC design comprises a low energy beam transport (LEBT)-section followed by a sc Drift Tube Linac (DTL) consisting of sc Crossbar-H-mode (CH) structures for acceleration up to 7.3 MeV/u. The latest milestones towards the new cw LINAC HELIAC (HELmholtz LInear ACcelerator) have been the successful tests and commissioning of the first demonstrator section with heavy ion beam in 2017 and 218 as well as the successful test under cryogenic conditions of the second CH-cavity in 2018. Now the third CH-cavity has been tested at cryogenic temperatures of 4 Kelvin at the Institute for Applied Physics (IAP) at Goethe University Frankfurt (GUF). The results of these measurements as well as the status of the HELIAC-project will be presented.  
poster icon Poster TUP004 [0.958 MB]  
 
TUP005 Cavity Designs for the CH3 to CH11 of the Superconducting Heavy Ion Accelerator HELIAC -1
SUSP009   use link to see paper's listing under its alternate paper code  
 
  • T. Conrad, M. Basten, M. Busch, H. Podlech, M. Schwarz
    IAP, Frankfurt am Main, Germany
  • K. Aulenbacher, W.A. Barth, F.D. Dziuba, V. Gettmann, T. Kürzeder, S. Lauber, J. List, M. Miski-Oglu
    HIM, Mainz, Germany
  • K. Aulenbacher
    KPH, Mainz, Germany
  • W.A. Barth, M. Heilmann, A. Rubin, A. Schnase, S. Yaramyshev
    GSI, Darmstadt, Germany
 
  In collaboration of GSI, HIM and Goethe University Frankfurt new designs for the CH-DTL cavities of the proposed Helmholtz Linear Accelerator (HELIAC) are developed. The cw-mode operated linac with a final energy of 7.3 MeV/u is intended for various experiments, especially with heavy ions at energies near the coulomb barrier. Currently twelve superconducting CH-cavities are considered which will be split into four different cryostats. Each cavity will be equipped with dynamic bellow tuners. After successful beam tests with CH0 as well as last surface preparations and ongoing rf tests with CH1 and CH2, CH3 to CH11 will be designed. Based on the successful test results, individual optimizations are carried out on the cavity design. Attention was paid to reduce production costs, for example by keeping the cavity diameter in each cryostat constant despite varying particle velocities and gap numbers. In addition to reaching the resonance frequency of 216.816 MHz and the influence of the bellow tuners on the frequency, the mechanical stability of the bellow tuners, the thermal effects on the cavity and the measures to mitigate secondary electron emission are investigated.  
 
TUP006
Space-Charge and Cavity Induced Beam Instabilities in Single Spoke Cavities  
 
  • A. Pathak
    University of Mumbai, Centre for Excellence in Basic Sciences, Mumbai, India
  • S. Krishnagopal
    BARC, Mumbai, India
 
  Modern high-intensity linear accelerators employ multiple families (with the different geometric beta) of single spoke resonator at lower velocity range. Though these structures are pretty efficient at lower velocities, the presence of an intense non-linear space-charge field in the beam and the quadrupolar asymmetry in these spoke cavities leads an unacceptable increase in beam emittance and halo growth. We perform a systematic study to determine the contribution from the non-linear space-charge field in the beam and the spoke cavities to the beam instabilities and resonances in the presence of statistical cavity and beam errors. Three-dimensional envelope equations are used to determine the stability condition of the envelope, and a self-developed fully three-dimensional particle-in-cell code PARTRACK was used to model the effect of the non-linear space-charge forces in the linac.  
 
TUP007 Electromagnetic Design of the Prototype Spoke Cavity for the JAEA-ADS Linac -1
 
  • J. Tamura, K. Hasegawa, Y. Kondo, F.M. Maekawa, S.I. Meigo, B. Yee-Rendón
    JAEA/J-PARC, Tokai-mura, Japan
  • E. Kako, T. Konomi, H. Sakai, K. Umemori
    KEK, Ibaraki, Japan
 
  The Japan Atomic Energy Agency (JAEA) is proposing an accelerator-driven subcritical system (ADS) as a future project to transmute long-lived nuclides to short-lived or stable ones. In the JAEA-ADS, a high-power proton beam of 30 MW with a final beam energy of 1.5 GeV is required with a high reliability. Furthermore, the accelerator needs to be operated in a continuous wave mode in order to be compatible with the reactor operation. As the first step toward the detailed design of the JAEA-ADS linac, we are planning to demonstrate a high-field measurement by prototyping a low-beta single spoke resonator (SSR1). We performed the electromagnetic design, and confirmed that the cavity performances of the SSR1 model with and without dimensional constraint.  
 
TUP008 HOMs Extraction Structure Design for HEPS 166.6 MHz Cavities -1
 
  • X.R. Hao
    IHEP, Beijing, People’s Republic of China
 
  Higher order modes (HOMs) may af{}fect beam stability and refrigeration requirements of superconducting cavity such as the 166.6~MHz superconducting(SC) cavity, which is studied at IHEP. Under certain conditions beam-induced HOMs can accumulate suf{}f{}icient energy to destabilize the beam or quench the SC cavities. In order to limit these ef{}fects, we considers the use of coaxial HOM couplers on the cut-of{}f tubes of the SC cavity. However, HOMs cannot be ef{}fectively extracted by HOM couplers. Therefore, it is necessary to design a HOMs extraction structure to introduce the dangerous modes from the cavity into the bundle tube, which are designed to couple to potentially dangerous modes while suf{}ficiently rejecting the fundamental mode. The HOMs extraction structure consists of an enlarged tubes, a coaxial structure, and the petal. The extraction of the dangerous modes and the suppression of the fundamental mode are realized by the petal structure and the coaxial structure. In order to verify the designs, a rapid prototype for the favored structure was fabricated and characterized on a low-power test-stand.  
poster icon Poster TUP008 [1.665 MB]  
 
TUP010 Mechanical Design and Horizontal Tests of a Dressed 166.6 MHz Quarter-wave β=1 SRF Cavity System -1
 
  • X.Y. Zhang, X.R. Hao, D.B. Li, Z.Q. Li, H.Y. Lin, Q. Ma, Z.H. Mi, Q.Y. Wang, P. Zhang
    IHEP, Beijing, People’s Republic of China
 
  Funding: This work has been supported by HEPS-TF project.
A 166.6 MHz quarter-wave β=1 superconducting proof-of-principle cavity has been designed and recently been dressed with a helium jacket, fundamental power coupler and tuner. The cavity was subsequently installed in a modified cryomodule and tested in a horizontal manner at both 4.2 K and 2 K. The helium jacket was successfully developed with a focus on minimizing frequency shift due to helium pressure fluctuation while retaining a reasonable tuning range. The Lorentz force detuning (LFD) and microphonics were also optimized during the design. The df/dp and LFD coefficient were measured to be -3.1 Hz/mbar and -0.8 Hz/(MV/m)2. These are in good agreement with simulations. Future work is mainly to reduce the stiffness of the cavity and further suppress the vibration mode of the inner conductor.
 
poster icon Poster TUP010 [1.245 MB]  
 
TUP011 QWR085 Design for Bisol Post Accelerator SCL2 -1
 
  • M. Chen, S. Chen, A.Q. Cheng, J.K. Hao, K.X. Liu, Y.Q. Liu, D.M. Ouyang, S.W. Quan, F. Zhu
    PKU, Beijing, People’s Republic of China
  • Z. Peng
    CIAE, Beijing, People’s Republic of China
 
  BISOL(Beijing Isotope-Separation-On-Line Neutron-Rich Beam Facility) is a new generation radioactive ion beam(RIB) facility[1]. It consists a CARR nuclear reactor, a high intensity deuteron accelerator and a post accelera-tor. QWR085 cavity is supposed to be used in SCL2 of post accelerator. This paper mainly talks about the elec-tromagnetic design, mechanical design and vibration damper design of QWR085.  
 
TUP012 Evaluation of High Performance Large Grain Medium Purity SRF Cavity From KEK -1
 
  • P. Dhakal, G. Ciovati, G.R. Myneni
    JLab, Newport News, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
We presented the RF measurement on a 1.3 GHz single cell cavity fabricated at KEK using large grain ingot niobium with RRR=107. The cavity reached to 35 MV/m with Q0 = 2.0×10zEhNZeHn at 2.0 K, record performance on the cavity made from medium purity ingot niobium. The cavity was cool down with different temperature gradient along the cavity axis in order to understand the flux expulsion mechanism when the cavity does through the superconducting transition and effect of trap residual magnetic field on the residual resistance. The measurement showed the excellent flux expulsion with the flux trapping sensitivity of 0.29 nΩ/mG for electro polished surface and 0.44 nΩ/mG for cavity followed by low temperature baking at 120°C for 12 hours.
We acknowledge KEK for sending this cavity for evaluations.
 
 
TUP013
Non-Evaporative Getter-Based Differential Pumping System for SRILAC at RIBF  
 
  • H. Imao
    RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama, Japan
  • O. Kamigaito, N. Sakamoto, T. Watanabe, Y. Watanabe, K. Yamada
    RIKEN Nishina Center, Wako, Japan
  • K. Oyamada
    SHI Accelerator Service Ltd., Tokyo, Japan
 
  Upgrades of the RIKEN heavy-ion linac (RILAC) involving a new superconducting linac (SRILAC) are undergoing to promote super-heavy element searches at the RIKEN radioactive isotope beam factory (RIBF). Stable ultra-high vacuum (<10-8 Pa) and particulate-free conditions are strictly necessary for keeping the performance of the superconductive radio frequency (SRF) cavities of the SRILAC. It is crucially important to develop neighboring warm sections to prevent contamination from the existing old RILAC and beamlines built almost four decades ago. In the present study, non-evaporative getter-based differential pumping systems were newly developed to achieve the pressure reduction from the existing beamline vacuum (10-5–10-6 Pa ) to the ultra-high vacuum within very limited length (<80 cm) ensuring the large beam aperture of more than 40 mm. They are also equipped with compact electrostatic particle removers. We will describe and discuss details of the design, construction and performance of the system.  
 
TUP014 Mechanical Design and Fabrication Aspects of Prototype SSR2 Jacketed Cavities -1
 
  • M. Parise, D. Passarelli, F. Ruiu
    Fermilab, Batavia, Illinois, USA
  • P. Duchesne, D. Longuevergne, D. Reynet
    IPN, Orsay, France
 
  A total of 35 Superconducting SSR2 spoke cavities will be installed in the PIP II SRF linac at Fermilab and a total of 8 prototype SSR2 cavities will be manufactured for the prototype cryomodule. In this paper, the mechanical design and fabrication aspects of the prototype jacketed SSR2 cavity will be presented. RF and mechanical design activities were conducted in parallel directly on the jacketed cavity in order to minimize the number of design iterations. Also, the lessons learned from other spoke cavities experiences (i.e. SSR1 at Fermilab and ESS double spoke at IPNO) were considered since the early stage of the design.  
 
TUP015
The Design and Construction of a Parallel-Feed SRF Linac  
 
  • P.B. Welander, Z. Li, M.H. Nasr, S.G. Tantawi
    SLAC, Menlo Park, California, USA
 
  Funding: Research funded by a SLAC Laboratory-Directed Research and Development award, supported by the U.S. Department of Energy, contract number DE-AC02-76SF00515.
Development of superconducting RF (SRF) accelerator technology that enables both higher gradient and higher efficiency is crucial for future machines. While much of the recent R&D focus has been on materials and surface science, our aim is to optimize the cavity geometry to maximize performance with current materials. The recent demonstration of a highly efficient parallel-feed normal-conducting RF structure at SLAC has served as a proof-of-concept. Instead of coupled elliptical cells, the structure employs isolated re-entrant cells. To feed RF power to the cavities, each cell is directly coupled to an integrated manifold. The structure is made in two parts, split along the beam axis, which are then joined. Applied to SRF, simulations suggest such a structure could nearly double the achievable gradient, while reducing cryogenic RF loss by more than half. We are experimentally verifying the concept using an X-band SRF design to be tested at SLAC.
 
 
TUP016 Quarter-wave Resonator with the Optimized Shape for Quantum Information Systems -1
 
  • S.V. Kutsaev, R.B. Agustsson, P.R. Carriere, A. Moro, A.Yu. Smirnov, K.V. Taletski
    RadiaBeam, Santa Monica, California, USA
  • A.N. Cleland, É. Dumur
    The University of Chicago, Chicago, Illinois, USA
  • Z.A. Conway
    ANL, Argonne, Illinois, USA
  • K.V. Taletski
    MEPhI, Moscow, Russia
 
  Funding: This work was supported by the U.S. Department of Energy, Office of High Energy Physics, under SBIR grant DE-SC0018753
Quantum computers (QC), if realized, could disrupt many computationally intense fields of science. The building block element of a QC is a quantum bit (qubit). Qubits enable the use of quantum superposition and multi-state entanglement in QC calculations, allowing a QC to simultaneously calculate millions of computations at once. However, quantum states stored in a qubit degrade with decreased quality factors and interactions with the environment. One technical solution to improve qubit lifetimes and network interactions is a circuit comprised of a Josephson junction located inside of a high Q-factor superconducting 3D cavity. RadiaBeam, in collaboration with Argonne National Laboratory and The University of Chicago, has developed a superconducting radio-frequency quarter-wave resonant cavity (QWR) for quantum computation. Here a 6 GHz QWR was optimized to include tapering of the inner and outer conductors, a toroidal shape for the resonator shorting plane, and the inner conductor to reduce parasitic capacitance. In this paper, we present the results of the qubit cavity design optimization, fabrication, processing and testing in a single-photon regime at mK temperatures.
 
 
TUP017
New SRF Disk and Spoke Structure  
 
  • R.A. Kostin, A. Kanareykin
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • I.V. Gonin, V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
 
  Euclid Techlabs in collaboration with Ferilab Technical Division is developing a new type of periodic compensated SRF structure, that has a significantly higher coupling coefficient between the cells than in conventional elliptical cavities with coupling through the apertures. The new cavity design - Disk and Spoke (DAS), is based on a combination of two ideas, the Disk and Washer (DAW) structure and the multi-spoke cavity. This resonator has strong coupling between the cells, providing stable accelerating fields in the presence of either manufacturing errors or mechanical detuning, and better HOM extraction. At the same time, the proposed structure has significantly higher G*R/Q (where G is a multiplication of Q factor and surface resistance) coefficient, i.e. lower cryogenic losses. The results of preliminary simulations are presented and discussed.  
 
TUP018 New SRF Structures Processed at the ANL Cavity Processing Facility -1
 
  • T. Reid, Z.A. Conway, B.M. Guilfoyle, M. Kedzie, M.P. Kelly, M.K. Ng
    ANL, Argonne, Illinois, USA
 
  Argonne National Laboratory (ANL) has extended high quality cavity processing techniques based on those developed for the International Linear Collider to several more complex superconducting RF cavities. Recently, these include a bunch lengthening harmonic cavity, a crabbing rf-dipole cavity, a compact half-wave cavity, and both medium and high frequency elliptical cavities. These systems are an improved version of the one originally developed for 1.3 GHz 9-cell cavities and include a second rotating electrical contact that can support multiple cathodes, necessary for optimum polishing in difficult cavity geometries. All include the possibility for external water cooling.  
poster icon Poster TUP018 [4.322 MB]  
 
TUP019 Status of High Temperature Vacuum Heat Treatment Program at IPN Orsay -1
 
  • M. Fouaidy, F. Chatelet, V. Delpech, F. Galet, D. Le Dréan, D. Longuevergne, R. Martret, G. Olry, T. Pépin-Donat
    IPN, Orsay, France
  • M. Baudrier, P. Carbonnier, E. Fayette, X. Hanus, Th. Proslier, D. Roudier, P. Sahuquet, C. Servouin
    CEA-DRF-IRFU, France
  • E. Cenni, L. Maurice
    CEA-IRFU, Gif-sur-Yvette, France
 
  In the framework of ESS, a vacuum furnace dedicated to High Temperature Heat Treatment under Vacuum (VH2T2) of SRF bulk Nb cavities was developed and commissioned in May 2016. This furnace is currently used for interstitial hydrogen removal (10h00 @ 650 °C) of two type of cavities: 1) the whole series of 26 ESS 352 MHz spoke resonators equipped with their Ti LHe tank well, 2) some prototypes of ESS high beta and medium beta cavities. Up to know IPN Orsay VH2T2 (10h00 @ 650 °C) was successfully applied to more than 16 cavities. In this paper we will first report about these VH2T2 tests. Finally, we have just started testing nitrogen infusion and nitrogen doping processes on samples and 1.3 GHz cavities: the preliminary results will be discussed.  
 
TUP020 Statistical Analysis of the 120°C Bake Procedure of Superconducting Radio Frequency Cavities -1
 
  • L. Steder, D. Reschke
    DESY, Hamburg, Germany
 
  DESY is and was very active in R&D related to SRF cavities. Many single and nine cell cavities with different surface treatment histories were tested vertically. Results of these cold tests are accelerating gradient and quality factor of the cavities. Using the large number of available datasets the parameters of the 120°C bake procedure, which is applied to avoid high-field Q-slope, are analysed. The impact of different durations and temperatures on accelerating gradient, quality factor and residual resistance is studied in detail and is compared to results obtained with the recently proposed procedure of modified low temperature bake. For this procedure additional four hours at temperatures around 75°C are implemented before the standard bake at about 120°C. Since the claim is, that cavities treated with such a modified procedure achieve extra-ordinary large accelerating gradients it is a very interesting research field for the European XFEL continuous wave mode upgrade. For this purpose cavities with high quality factors are needed, but in addition large maximal accelerating fields are required to maintain high energies in the pulsed operation mode of the accelerator.  
poster icon Poster TUP020 [0.747 MB]  
 
TUP021 Effect of Cathode Rotation and Acid Flow in Vertical Electropolishing of 1.3 GHz Niobium Nine-Cell Cavity -1
 
  • V. Chouhan, Y.I. Ida, K.N. Nii, T.Y. Yamaguchi
    MGH, Hyogo-ken, Japan
  • H. Hayano, S. Kato, H. Monjushiro, T. Saeki
    KEK, Ibaraki, Japan
 
  We have been carrying out R&D on vertical electropolishing (VEP) technique to establish it as an alternate of the horizontal EP (HEP) technique used for the surface treatment of niobium (Nb) superconducting RF (SRF) cavities. We have earlier reported on a VEP parameter study for 1.3 GHz single and nine-cell Nb cavities. The optimized VEP parameters and a unique rotating cathode yielded uniform removal and a smooth surface in the single cell cavity. The unique cathode and a dual flow mechanism for acid circulation were applied to improve the removal uniformity in the nine-cell cavity. The vertically electropolished single and nine cell cavities achieved the same RF performance as achieved after the HEP processes. We are making efforts to further improve the removal uniformity in the nine-cell cavity. Here, we report on a VEP of the 1.3 GHz Nb nine-cell cavity at a higher cathode rotation speed of 50 rpm. The VEP results reveal that the speed could be considered for improving the uniformity in removal while maintaining the surface smoothness. Required improvements in the VEP facility and acid flow condition for achieving uniform EP and a smooth surface are also described.  
 
TUP022 Fermilab EP Facility Improvement -1
 
  • F. Furuta, D.J. Bicepresenter, A.C. Crawford, T.J. Ring
    Fermilab, Batavia, Illinois, USA
 
  Electro-chemical Polishing (EP) is one of the key technologies of surface treatments for niobium superconducting cavities. We have established a single-cell scale horizontal electro-polishing facility at Fermilab and routinely processed the niobium cavities with the frequencies of 1.3 GHz to 3.9 GHz. The precise control of EP parameters, especially the temperatures of cavity outside wall, allows the uniform removal over the cell with the variation of ±15%. Here we report the details of our EP process and recent improvements on our EP facility at Fermilab.  
poster icon Poster TUP022 [1.711 MB]  
 
TUP023 Experience of LCLS-II Cavities Radial Tuning at DESY -1
 
  • A. Sulimov, J.H. Thie
    DESY, Hamburg, Germany
  • A. Gresele
    Ettore Zanon S.p.A., Nuclear Division, Schio, Italy
  • A. Navitski
    RI Research Instruments GmbH, Bergisch Gladbach, Germany
  • A.D. Palczewski
    JLab, Newport News, Virginia, USA
 
  Radial tuning (rolling) was applied to three LCLS-II cavities to prevent that their lengths exceed the technical limits. The cavities have a reduced frequency due to additional material removal during cavity treatment well beyond the baseline recipe. The mechanical condition of the cavities was relatively soft because of the thermal history and the niobium manufacture requirement of an optimal flux expulsion. The niobium was highly recrystallized by 3 hours annealing at 900°C and 975°C respectively. Each cavity received an inner surface treatment of 200 µm electro-polishing (EP) and an external 30 µm buffered chemical polishing (BCP) as part of the baseline recipe. Each cavity received an addition ~100 µm of chemical removal along with a second annealing treatment before the radial tuning process. Detailed information about the accuracy and homogeneity of LCLS-II cavities rolling is presented as well as results of field distribution analysis for TM011 zero-mode with a comparison to standard cavities.  
poster icon Poster TUP023 [0.521 MB]  
 
TUP024 Radial Tuning Devices for 1.3 GHz TESLA Shape Cavities -1
 
  • A. Sulimov, J.H. Thie
    DESY, Hamburg, Germany
 
  Radial tuning devices at DESY can be applied to any TESLA shape 1.3 GHz cavity to reduce its elongation due to excessive additional material removal (>300 µm) or to compensate critical manufacturing uncertainties. Radial deformation of cavity cells can be provided by a special chain or a rolling device with three rollers. The chain distributes the radial forces on the equator area around the cell. The rollers are moving radially in relation to the rotating cavity and provide an equator diameter reduction. Both devices have the contour close to the cell shape at the equator area. The required equator radius deviation depends on the tuning target and usually varies between (0.02…0.60) mm. Different aspects of the tuning procedure and material properties are described using the example of cavity rolling.  
poster icon Poster TUP024 [0.252 MB]  
 
TUP025
Preliminary Vertical Test Result and Plan for 5-Cell 650 MHz Cavity  
 
  • W. Xu, T. Hayes, D. Holmes, G.T. McIntyre, K. Mernick, P. Orfin, R. Porqueddu, S.K. Seberg, F. Severino, K.S. Smith, R. Than, B.P. Xiao, A. Zaltsman
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work supported by LDRD program of Brookhaven Science Associ-ates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE.
Currently, we carry out performance study on a 5-cell 650 MHz SRF cavity with various post-processing and cooling down procedure. The first round of post-processing is to get a baseline performance of the cavity, which is only BCP, HPR and 600°C bakeout. The vertical test found field emission limit at 18 MV. The cavity was pulled out from VTF for additional HPR. This paper will address the post-processing, vertical test and discuss test results and plan.
 
 
TUP026 Vibro-tumbling as an Alternative to Standard Mechanical Polishing Techniques for SRF Cavities -1
 
  • E. Chyhyrynets, O. Azzolini, V.A. Garcia, G. Keppel, C. Pirapresenter, F. Stivanello, L. Zanotto
    INFN/LNL, Legnaro (PD), Italy
 
  Funding: Work supported by the INFN V group experiment TEFEN, Agreement N. KE2722/BE/FCC and from the European Union’s H2020 Framework Programme under grant agreement no. 764879 (EASITrain)
Centrifugal Barrel Polishing (CBP) is a common tool in the Nb bulk SC cavities production, prior to elec-tropolishing (EP). Indeed, the mechanical polishing is fun-damental also in the superconducting thin film resonant cavities in which one of the main issues that limits the per-formances is the surface preparation. A promising vi-bro-tumbling technique is being studied and implemented with a possibility to replace or improve mechanical treat-ment steps (grinding, barrel polishing). The simplic-ity of the technology allows it to adapt to any cavity geom-etry, both for Nb and Cu materials. The presented work contains last results on 6 GHz cavities obtained at LNL-INFN, both Nb bulk and Cu cavities.
 
poster icon Poster TUP026 [5.584 MB]  
 
TUP027 Vertical Electropolishing of Niobium Nine-Cell Cavity with a Cavity Flipping System for Uniform Removal -1
 
  • K.N. Nii, V. Chouhan, Y.I. Ida, T.Y. Yamaguchi
    MGH, Hyogo-ken, Japan
  • H. Hayano, S. Kato, H. Monjushiro, T. Saeki
    KEK, Ibaraki, Japan
 
  Marui Galvanizing Co., Ltd. has been developing vertical electropolishing (VEP) technology for single and nine-cell niobium superconducting radio frequency cavities using a unique cathode namely Ninja cathode in collaboration with KEK. The VEP process usually results in non-uniform removal with a large asymmetry along the cavity length. In order to suppress the asymmetry in removal, we are making different approaches. Flipping of the cavity during the VEP process is one of the approaches applied so far. A unique VEP setup, which allows the flipping of a multi-cell cavity, has been developed as reported earlier. Here, we report the improvement in the setup with automation for cavity flipping. VEP experiments were conducted with the improved system. VEP parameters were studied and the VEP results including the removal trend are discussed in detail.  
poster icon Poster TUP027 [1.347 MB]  
 
TUP028 Development of Vertical Electropolishing Facility for Nb 9-Cell Cavity (3) -1
 
  • Y.I. Ida, V. Chouhan, K.N. Niipresenter
    MGH, Hyogo-ken, Japan
  • T. Akabori, G. Mitoya, K. Miyano
    HKK, Morioka, Japan
  • Y. Anetai, F. Takahashi
    WING. Co.Ltd, Iwate-ken, Japan
  • H. Hayano, S. Kato, H. Monjushiro, T. Saeki, M. Sawabe
    KEK, Ibaraki, Japan
 
  The 1st report was delivered in May, 2018 at the IPAC 18 in Vancouver, Canada. The 2nd report was delivered in September, 2018 at the LINAC 18 in Beijing, China. We will make our 3rd report in July, 2019 at the SRF-19 in Dresden, Germany. There will be two main points this time. The first is that by using our improved Ninja Electrode Premium, we can out-perform our number one and number two competitors in terms of uniform electropolishing of the interior of the 9-cell cavity. The second point is that we can remove hydrogen gas, reacted during electropolishing, from the cavity chambers in a manner that has not been successfully achieved by 1st report, May 2018 and 2nd report, September 2018. We will report our 9-cell vertical polishing revolver-type unit that solves the above two problems.  
poster icon Poster TUP028 [0.444 MB]  
 
TUP029 An Experimental Analysis of Effective EP Parameters for Low-Frequency Cylindrical Nb Cavities -1
 
  • C.E. Reece
    JLab, Newport News, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Work supported by the U.S. DoE, Office of Science, Office of Basic Energy Sciences.
While the basic process of electropolishing niobium with 1:9 HF:H2SO4 electrolyte has been well characterized, the specific process parameters used to electropolish different superconducting radio frequency (SRF) cavity geometries requires thoughtful attention. One seeks to realize confidently local diffusion-limited polishing at each point on the surface while maximizing uniformity of removal rate. Since the reaction rate is temperature dependent, this implies that one must manage the cavity surface temperature during polishing. Too-high applied voltage aggravates temperature and thus removal non-uniformity, but too-low applied voltage risks placing the large-diameter locations "off the current plateau," yielding etching rather than polishing. The majority of recent experience has been with elliptical L-band SRF cavities and some half-wave cavities at ANL. Lower frequency cavities with increased surface area and larger cathode-to-equator distance require fresh analysis and optimization. In preparation for SNS PPU project, JLab performed some EP process development runs with SNS high beta cavities to help identify viable parameter regimes for communication to cavity vendors. Results from this study are presented.
 
 
TUP030
Automation of Particulate Characterization  
 
  • J.K. Spradlin, C.E. Reecepresenter, O. Trofimova, A-M. Valente-Feliciano
    JLab, Newport News, Virginia, USA
 
  Funding: Notice: This manuscript has been authored by Jefferson Science Associates, LLC under Contract No. DE-AC05-06OR23177 with the U.S. Department of Energy.
Foreign particles residing on the field carrying surface of accelerator cavities are a known mechanism for field emission. Developing the methods and tools for collecting and characterizing particles found in an accelerator enables process development towards field emission free SRF cavities. Methods are presented for sampling assemblies, components, processes, and environmental conditions utilizing forensic techniques with specialized tooling. Sampling activities to date have produced an inventory of over 850 GSR spindles. Traditional SEM + EDS analysis of this volume of spindles is challenged by labor investment, spindle sampling methods, and the subsequent data pipeline which ultimately results in a statically inadequate dataset for any particulate distribution characterization. A complete systematic analysis of the spindles is enabled by third party software controlling SEM automation for EDS data acquisition. Details of spindle creation, collection equipment, component sampling, automating particle assessment, and data analysis used to characterize samples from beamline elements in CEBAF are presented.
 
poster icon Poster TUP030 [3.257 MB]  
 
TUP031 Heat Treatment for Jacketed Half-wave Resonator Cavity -1
 
  • Y. Jung, B.H. Choi, D.H. Gil, M.O. Hyunpresenter, H. Kim, J.W. Kim, M.S. Kim, D.Y. Lee, J. Lee, S. Lee
    IBS, Daejeon, Republic of Korea
 
  Vertical tests of a prototype half-wave resonator cavity are being tested. The performance of the cavities, such as quality factor and accelerating electrical field, are measured and compared to the target design value. In previous study, we reported the effect of the heat treatment on a prototype bare HWR cavity. We baked a jacketed HWR cavity to improve a performance for 10 h at 650°C. In this study, we will report the effect of the heat treatment on the jacketed HWR cavity.  
 
TUP032 Modal Analysis and Vibration Test for Quarter Wave Resonator for RAON -1
 
  • M.O. Hyun, H.C. Jung, Y. Kim, M. Lee
    IBS, Daejeon, Republic of Korea
 
  Funding: This paper was supported by the Rare Isotope Science Project (RISP), which is funded by the Ministry of Science and ICT (MSIT) and National Research Foundation (NRF) of the Republic of Korea.
The Rare Isotope Science Project (RISP) in the Institute of Basic Science (IBS), Korea, is developing and con-structing the multi-purpose linear accelerator at the north side of Daejeon, South Korea. RISP accelerator (RAON) is composed with low-energy region (SCL3) and high-energy region (SCL2), and low-energy region is made with quarter-wave resonator (QWR) and half-wave resonator (HWR) when high-energy region is made with single spoke resonator type-1 (SSR1) and type-2 (SSR2). This paper shows about the initial resonance issues of QWR superconducting (SC) cavity during cold test and SRF disturbance measurement. Afterwards, this paper shows the modal analysis and vibration test of QWR SC cavity.
 
poster icon Poster TUP032 [0.584 MB]  
 
TUP033 Modal Analysis of the EXFEL 1.3 GHz Cavity and Cryomodule Main Components and Comparison with Measured Data -1
 
  • S. Barbanotti, A. Bellandi, J. Branlard, K. Jensch
    DESY, Hamburg, Germany
 
  Future upgrades of the European X-ray Free Electron Laser (EXFEL) may require driving the linac at higher duty factor, possibly extending to Continuous Wave (CW) mode. An R&D program has started at DESY, to prepare for a CW upgrade. Cryomodules are being tested in CW mode in our CryoModule Test Bench (CMTB) to study the performance and main issues for such an operation mode. Sensitivity to vibration causing microphonics is one of the main concerns for the CW operation in mode. Therefore a detailed analysis is being performed to evaluate the frequency spectrum of the EXFEL cryomodule main components: the cavity itself, the cavity string, the cold mass and the vacuum vessel. Finite Element Modal Analyses have been performed and the results compared with data measured at the CMTB. This paper summarizes the main results and conclusions of such a study.  
 
TUP034 Microphonics Testing of LCLS II Cryomodules at Jefferson Lab -1
 
  • T. Powers, N.C. Brock, G.K. Davis
    JLab, Newport News, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177
Jefferson Lab is partnering with Fermilab to build the 36 cryomodules for the LCLS II accelerator that will be installed at SLAC. The cavities have design loaded-Q of 4×107, which means that it has a control bandwidth of 16 Hz. The JLab prototype cryomodule was instrumented with a series of seven accelerometers, and impulse hammer response measurements were made while the cryomodule was being built and after it was installed in the JLab cryomodule test facility. This was done so that we could understand the shapes of the modes of the structure. These results were compared to impulse hammer testing from the outside of the cryomodule and to individual cavity frequency shifts when the cryomodule was cold. The prototype cryomodule had excessive microphonics of 150 Hz peak due to a thermos-acoustic oscillation. Design modifications were implemented and subsequently the cryomodules had microphonics on the order of 10 to 20 Hz. Results of the modal analysis as well as the background microphonics observed when operated under various cryogenic conditions and with different modifications will be presented.
 
 
TUP036
Commissioning of Klystron Transmitters up to 270 kW at 1.3 GHz  
 
  • B. Schriefer, W. Anders
    HZB, Berlin, Germany
 
  In Berlin-Adlershof the Helmholtz-Zentrum Berlin (HZB) is constructing the energy recovery linac ’BERLinPro’. Three klystron transmitters each 270 kWCW at 1.3 GHz are installed at the injection path of the ERL. The RF plant includes circulators and water loads. This paper describes the commissioning of the first klystron, calibration of the RF level control system as well as comparison with calorimetric output power measurements to verify the results.  
 
TUP037 Construction of Superconducting Linac Booster for Heavy-Ion Linac at RIKEN Nishina Center -1
 
  • K. Yamada, T. Dantsuka, H. Imao, O. Kamigaito, K. Kusaka, H. Okuno, K. Ozeki, N. Sakamoto, K. Suda, T. Watanabe, Y. Watanabe
    RIKEN Nishina Center, Wako, Japan
  • H. Hara, A. Miyamoto, K. Sennyu, T. Yanagisawa
    MHI-MS, Kobe, Japan
  • E. Kako, H. Nakai, H. Sakai, K. Umemori
    KEK, Ibaraki, Japan
 
  At RIKEN Nishina Center, the RIKEN Heavy-Ion Linac (RILAC) is undergoing an upgrade of its acceleration voltage in order to allow it further investigation of new super-heavy elements. In this project, a new superconducting (SC) booster linac, so-called SRILAC, is being developed and constructed. The SRILAC consists of 10 TEM quarter-wavelength resonators made of pure niobium sheets which operate at 4 K. The target performance of each cavity is set as Q0 of 1×109 with its accelerating gradient of 6.8 MV/m. Recently we succeeded to develop high performance SC-cavities which satisfies the requirement with a wide margin. The cryomodule assembly is under way, and installation of cryomodules and He liquefaction system will be completed by the end of FY2018. The cooling-down test is scheduled in the Q1 of FY2019. This contribution makes a report on the construction status of the SRILAC.  
 
TUP039
Flux Expulsion Lessons Learned from LCLS-II  
 
  • S. Posen, A. Grassellino, E.R. Harms, O.S. Melnychuk, A.S. Romanenko, D.A. Sergatskov, N. Solyak, G. Wu
    Fermilab, Batavia, Illinois, USA
  • D. Gonnella, T.J. Peterson
    SLAC, Menlo Park, California, USA
  • A.D. Palczewski
    JLab, Newport News, Virginia, USA
 
  Trapped magnetic flux can be a significant source of Q0 degradation, particularly in applications where high Q0 is crucial. Recent R&D studies at Fermilab revealed that the fraction of external field that is trapped in the wall of the cavity during cooldown can be significantly influenced by a number of factors including the cooldown itself, by thermal gradients, and by heat treatment during processing. These lessons learned were applied to cavities in the LCLS-II project, including experiments on single cell cavities to study the material, modification of the heat treatment, and optimization of the cryomodule. In this contribution, we discuss the influence of these modifications to improve magnetic flux expulsion on the performance of cryomodules for LCLS-II.  
 
TUP041 SRF testing for Mainz Energy Recovering Superconducting Accelerator MESA -1
 
  • T. Stengler, K. Aulenbacher, F. Hug, S.D.W. Thomas
    KPH, Mainz, Germany
  • K. Aulenbacher
    GSI, Darmstadt, Germany
  • K. Aulenbacher
    HIM, Mainz, Germany
 
  Funding: This work is supported by the German Research Foundation (DFG) under the Cluster of Excellence "PRISMA+" EXC 2118/2019
The two superconducting radio frequency acceleration cryomodules for the new multiturn ERL ’Mainz Energy Recovering Superconducting Accelerator’ MESA at Johannes Gutenberg-Universität Mainz have been fabricated and are currently under testing at the Helmholtz Institut Mainz. These modules are based on the ELBE modules of the Helmholtz Center Dresden-Rossendorf but are modified to suit the high current and energy-recovering operation at MESA. The energy gain per module per turn should be 25 MeV, provided by two TESLA cavities, which were vertically tested at DESY, Hamburg, Germany. These tests showed an excellent performance of the quench limit and quality factor for three out of the four cavities. The fourth cavity has a lower but still acceptable quench limit and quality factor. In order to validate the performance of the fully assembled cryomodules after delivery to Mainz a test stand has been set up at the Helmholtz Institut Mainz. The test stand is described in detail and the status of the module testing is reported.
 
 
TUP042 Measurement of Mechanical Vibration of SRILAC Cavities -1
 
  • O. Kamigaito, K. Ozeki, N. Sakamoto, K. Suda, K. Yamada
    RIKEN Nishina Center, Wako, Japan
 
  Mechanical vibration of quarter-wavelength resonators of SRILAC, the superconducting booster of the RIKEN heavy-ion linac, was measured during a vertical cold test. The measurements were performed for fully assembled cavities as well as for bare niobium cavities without the titanium jacket. In the procedure, the instantaneous resonant frequencies were measured for 10 seconds at a time interval of 1 ms and were recorded as a time series. The frequencies were analyzed by means of conventional signal analysis. The power spectrum was deduced from the autocorrelation function calculated with the fluctuation of resonant frequencies. Although the vibration amplitudes were smaller in the cavities assembled with the titanium jacket, we could not find a clear reason for this.  
poster icon Poster TUP042 [6.957 MB]  
 
TUP043 Ab-initio Study of Atomic Scale Interaction Among Nb, Sn, Cl, and O -1
 
  • A.B. Tesfamichael, T. Arias
    Cornell University, Ithaca, New York, USA
 
  Funding: Center for Bright Beam (CBB)
We employed a combination of ab-initio calculations and statistical mechanical models to understand the nature of atomic scale interaction among Nb, Sn, Cl, and O. Because of the profound nature of the interaction, we began our study by focusing only on the interaction of Nb with Sn in the absence of Cl and O. Using Density Functional Theory (DFT) we calculated: (1), binding energy of both vacant and interstitial of the super cell for both Nb and Sn atoms (2), rate of diffusion and re-evaporation upon transportation of Sn atom across z-axis from bulk Nb layer (3), electron transfer and electric field upon transportation of Sn atom both across z-axis and xy-plane from bulk Nb layer. Our calculation indicated 30-40% difference from experimental results. Therefore, we conclude that the presence of oxides is important and also Cl impurity can not not be avoided.
 
 
TUP045 Ab Initio Calculations on Impurity Doped Niobium and Niobium Surfaces -1
 
  • N. Sitaraman, T. Arias
    Cornell University, Ithaca, New York, USA
  • R.G. Farber, S.J. Sibener, R.D. Veit
    The University of Chicago, Chicago, Illinois, USA
  • M. Liepe, J.T. Maniscalco
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Funding: This work was funded by the Center for Bright Beams
We develop and apply new tools to understand Nb surface chemistry and fundamental electronic processes using theoretical ab initio methods. We study the thermodynamics of impurities and hydrides in the near-surface region as well as their effect on the surface band gap. This makes it possible for experimentalists to relate changes in STM dI/dV measurements resulting from different preparations to changes in subsurface structure. We also calculate matrix elements for electron-impurity scattering in Nb for common impurities O, N, C, and H. By transforming these matrix elements into a Wannier function basis, we calculate lifetimes for a dense set of states on the Fermi surface and determine the mean free path as a function of impurity density. This technique can be generalized to calculate other scattering amplitudes and timescales relevant to SRF theory.
 
 
TUP046 Low Frequency, Low Beta Cavity Performance Improvement Studies -1
 
  • P. Kolb, R.E. Laxdal, Z.Y. Yao
    TRIUMF, Vancouver, Canada
 
  In recent years, new discoveries such as N2 doping and infusion lead to a significant increases in Q0 and accelerating gradient for 1.3 GHz, β=1 elliptical cavities. To understand and to adapt these treatments for lower frequency, \beta < 1 cavities, two coaxial test cavities, one quarter-wave resonator (QWR) and one half-wave resonator (HWR), have been built and put through a systematic study of these new treatments to show the effectiveness of these treatments at different frequencies. These cavities are tested in their fundamental mode and several higher order modes to study the frequency dependence of new cavity treatments such as N2 doping and infusion. Results of these studies are presented.  
 
TUP047
Field and Frequency Dependence of the Surface Resistance of Superconducting Microwave Resonators  
 
  • P.N. Koufalis, M. Ge, M. Liepe, J.T. Maniscalcopresenter, R.D. Porter
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Understanding the frequency and field dependence of the surface resistance of superconducting niobium microwave resonators is important for the maximization of quality factor and accelerating gradients of higher frequency cavities. Results of this dependence at 500, 1300, 2600, and 3900 MHz for various cavity treatments, including high temperature nitrogen-doping, low temperature infusion, and vacuum heat treatments are presented in this letter. We demonstrate that the temperature dependent component of the surface resistance decreases with increasing field strength for 2.6 and 3.9 GHz cavities without the need for nitrogen-doping or low temperature infusion. Similarly, it is demonstrated that doping or infusion treatments can further intensify this effect at 2.6 and 3.9 GHz and introduce it to 1.3 GHz cavities.  
 
TUP048
Field Dependent Surface Resistance Variation as a Function of the Frequency  
 
  • M. Martinello, M. Checchin, A. Grassellino, O.S. Melnychuk, S. Posen, A.S. Romanenko, D.A. Sergatskov
    Fermilab, Batavia, Illinois, USA
 
  A focused study on the field dependence of the temperature-dependent component of the surface resistance (BCS component) as a function of the cavity resonant frequency is presented. The study analyzes cavities with different resonant frequency (650 MHz, 1.3 GHz, 2.6 GHz and 3.9 GHz) processed with state-of-the-art surface treatments (EP, BCP, 120°C baking and N-doping). The findings show that the decreasing of the BCS surface resistance may appear even in clean niobium cavities if the resonant frequency is high enough, which suggests new routes toward understanding the anti-Q slope effect.  
 
TUP049 Maximum Performance of Cavities Affected by the High-field Q-slope (HFQS) -1
 
  • G. Ciovati
    JLab, Newport News, Virginia, USA
  • A.V. Gurevich, I.P. Parajuli
    ODU, Norfolk, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The work of I. P. and A. G. is supported by NSF Grant PHY 100614-010.
The performance of high-purity, bulk niobium SRF cavities treated by chemical processes such as BCP or EP is limited by the so-called high-field Q-slope (HFQS). Several models and experimental studies have been proposed and performed over the years to understand the origin of these anomalous losses but a general consensus on what these orgins are is yet to be established. In this contribution, we present the results from the RF tests of several 1.3 GHz single-cell cavities limited by the HFQS and tested using a variable input coupler. This allowed to maintain close to critical coupling even at high field and the data showed that the HFQS did not saturate and that in some cases a power dissipation of up to 200 W at 2 K could be sustained without quench.
 
 
TUP050 A Multi-layered SRF Cavity for Conduction Cooling Applications -1
 
  • G. Ciovati, G. Cheng, E. Daly, G.V. Eremeev, J. Henry, R.A. Rimmer
    JLab, Newport News, Virginia, USA
  • I.P. Parajuli
    ODU, Norfolk, Virginia, USA
  • U. Pudasaini
    The College of William and Mary, Williamsburg, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Some of the work was supported by the 2008 PECASE Award of G. Ciovati. I. Parajuli is supported by NSF Grant PHYS-100614-010
Industrial application of SRF technology would favor the use of cryocoolers to conductively cool SRF cavities for particle accelerators, operating at or above 4.3 K. In order to achieve a lower surface resistance than Nb at 4.3 K, a superconductor with higher critical temperature should be used, whereas a metal with higher thermal conductivity than Nb should be used to conduct the heat to the cryocoolers. A standard 1.5 GHz bulk Nb single-cell cavity has been coated with a ~2 µm thick layer of Nb3Sn on the inner surface and with a 5 mm thick Cu layer on the outer surface for conduction cooled applications. The cavity performance has been measured at 4.3 K and 2.0 K in liquid He. The cavity reached a peak surface magnetic field of ~40 mT with a quality factor of 6×109 and 3.5×109 at 4.3 K, before and after applying the thick Cu layer, respectively.
 
 
TUP051 Progress Towards Commissioning the Cornell DC Field Dependence Cavity -1
SUSP014   use link to see paper's listing under its alternate paper code  
 
  • J.T. Maniscalco, T. Gruber, A.T. Holic, M. Liepe
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  The Cornell DC Field Dependence Cavity is a new coaxial test resonator designed to study the impact of strong (up to 200 mT or more) DC surface magnetic fields on the superconducting surface resistance, providing physical insight into the root of the ‘‘anti-Q-slope’’ and probing critical fields. In this report we report progress in the commissioning of this new apparatus, including finalized design elements and results of prototype tests.  
 
TUP052 Design and Commissioning of a Magnetic Field Scanning System for SRF Cavities -1
SUSP031   use link to see paper's listing under its alternate paper code  
 
  • I.P. Parajuli, J.R. Delayen, A.V. Gurevich, J. Nice
    ODU, Norfolk, Virginia, USA
  • G. Ciovati, W.A. Clemens, J.R. Delayen
    JLab, Newport News, Virginia, USA
 
  Funding: Work supported by NSF Grant 100614-010. G. C. is supported by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Trapped magnetic vortices are one of the leading sources of residual losses in SRF cavities. Mechanisms of flux pinning depend on the materials treatment and cool-down conditions. A magnetic field scanning system using flux-gate magnetometers and Hall probes has been designed and built to allow measuring the local magnetic field of trapped vortices normal to the outer surface of 1.3 GHz single-cell SRF cavities at cryogenic temperatures. Such system will allow inferring the key information about the distribution and magnitude of trapped flux in the SRF cavities for different material, surface preparations and cool-down conditions.
 
 
TUP053 Optimal Thermal Gradient for Flux Expulsion in 600°C Heat-treated CEBAF 12 GeV Upgrade Cavities -1
 
  • R.L. Geng, F. Marhauser, P.D. Owen
    JLab, Newport News, Virginia, USA
 
  We will present results on measurement of flux expulsion in CEBAF 12 GeV upgrade cavities and original CEBAF cavities and the search for optimal thermal gradient for reducing the trapped flux in cavities installed in CEBAF linacs. Preliminary measurements of one C100 cavities has shown that a nearly perfect flux expulsion can be achieved at an optimal thermal gradient - a surprising result contrary to the expectation of zero flux expulsion for 600°C heat treated niobium cavities. These results could lead to a cost-effective path for improving the quality factor of cavities installed in CEBAF and ultimately saving accelerator operation cost.  
 
TUP054 How Is Flux Expulsion Affected by Geometry: Experimental Evidence and Model -1
 
  • D. Longuevergne
    IPN, Orsay, France
 
  Measurements of magnetic sensitivity to trapped flux on several type of cavity geometries have been performed at IPNO showing a clear geometrical effect. Magnetic sensitivity depends not only on material quality but also on the cavity geometry and on the residual magnetic field orientation. A presentation of experimental data will be done. These will be as well compared to the theoretical magnetic sensitivities calculated thanks to a simple Labview routine  
poster icon Poster TUP054 [1.312 MB]  
 
TUP055 Nonlinear Dynamics and Dissipation of Vortex Lines Driven by Strong RF Fields -1
SUSP033   use link to see paper's listing under its alternate paper code  
 
  • M.R.P. Walive Pathiranage, A.V. Gurevich
    ODU, Norfolk, Virginia, USA
 
  Trapped vortices can contribute significantly to a residual surface resistance of superconducting radio frequency (SRF) cavities but the nonlinear dynamics of flexible vortex lines driven by strong rf currents has not been well understood. Here we report extensive numerical simulations of large-amplitude oscillations of a trapped vortex line under the strong rf magnetic field. The rf power dissipated by an oscillating vortex segment driven by the rf Meissner currents was calculated by taking into account the nonlinear vortex line tension, vortex mass and a nonlinear Larkin-Ovchinnikov and overheating viscous drag force. We calculated the field dependence of the surface resistance Rs and showed that at low frequencies Rs(H) increases with H but as the frequency increases, Rs(H) becomes a non-monotonic function of H which decreases with H at higher fields. These results suggest that trapped vortices can contribute to the extended Q(H) rise observed on the SRF cavities.  
poster icon Poster TUP055 [1.744 MB]  
 
TUP056 A First-Principles Study on Magnetic Flux Trapping at Niobium Grain Boundaries -1
 
  • P. Garg, K.N. Solanki
    Arizona State University, Tempe, USA
  • T.R. Bielerpresenter
    Michigan State University, East Lansing, Michigan, USA
  • L.D. Cooley
    NHMFL, Tallahassee, Florida, USA
 
  Niobium is basis for all superconducting radio frequency cavities, a technology that accelerates charged particle beams to energy levels not possible by other means. When cavities are pushed to limits, significant heating appears at extended material defects, like grain boundaries. Therefore, it is crucial to understand how grain boundary (GB) structure and associated properties lead to trapping of magnetic field, and whether GB itself has any unusual magnetic behavior. Using first-principles calculations, external magnetic field along the GB plane was simulated within an all-electron full-potential linearized augmented plane-wave framework. A ground state with non-zero flux, indicative of flux trapping, was obtained at some grain boundaries, this outcome being influenced strongly by GB local structure. Furthermore, electronic density of states and charge-transfer calculations suggested non-zero spin polarization at grain boundaries, which may be consistent with recent observations of unusual paramagnetic magnetization as a function of specimen surface area for cavity-grade niobium.  
 
TUP057 Study of Flux Trapping Variability between Batches of Tokyo Denkai Niobium used for the LCLS-II Project and Subsequent 9-cell RF Loss Distribution between the Batches -1
 
  • A.D. Palczewski
    JLab, Newport News, Virginia, USA
  • D. Gonnella
    SLAC, Menlo Park, California, USA
  • O.S. Melnychuk, D.A. Sergatskov
    Fermilab, Batavia, Illinois, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
During the LCLS-II project a second batch of niobium was procured from Tokyo Denkai Co Ltd in order to make additional cavities. The original production material came from Two vendors Tokyo Denkai Co., Ltd. (TD) and Ningxia Orient Tantalum Industry Co., Ltd. (OTIC/NX)). It was found TD niobium required a lower annealing temperature (900°C) to obtain satisfactory flux expulsion characteristics compared to NX which required a slightly higher annealing temperature (950°-975°C). In order to ensure the new TD material performed equivalent to the niobium produced 4 year before after 900°C annealing; each heat lot of niobium had its flux expulsion characteristics parametrized and custom thermal treatments developed for each lot. Subsequent pure heat lot 9 cell cavities were made and tested. We will look at the flux expulsion characteristics of each lot, and RF loss of the 9-cell cavities produced using the individual heat lots.
 
poster icon Poster TUP057 [1.446 MB]  
 
TUP058 Characterization of Small AMR Sensors in Liquid Helium to Measure Residual Magnetic Field on Superconducting Samples -1
 
  • G. Martinet
    IPN, Orsay, France
 
  Trapped residual magnetic flux is responsible of residual resistance degradation on superconducting materials used in SRF technologies. To characterize this effect on superconducting samples, compact sensors are required to mount on sample characterization devices. In this paper, we present results on AMR sensors supplied from different manufacturers in the temperature range from 4.2 K up to 300 K.  
 
TUP059 Investigation of Trapped Flux Dynamics via DC-Magnetic Quenching -1
 
  • P. Nunez von Voigt, J. Knobloch, O. Kugeler
    HZB, Berlin, Germany
  • J. Knobloch
    University of Siegen, Siegen, Germany
 
  Trapped magnetic flux increases the surface resistance in superconducting radio-frequency cavities. A better understanding of its behaviour could help to develop a method of expelling trapped flux from the superconducting surface. Using a superconducting coil with ferrite core attached to a 3 GHz sample Niobium cavity fully immersed in liquid Helium, we were able to subject the cavity walls to unusually large magnetic fields (estimated > 150 mT) and create magnetic quenches. With Fluxgate sensors attached in three spatial directions inside the cavity, we were able to monitor the quench dynamics and extract parameters of the flux dynamics from the hysteretic behaviour of the measured fields resulting from the applied coil current. First results of manipulation of the trapped flux with high magnetic fields are presented.  
 
TUP060 Development of Temperature and Magnetic Field Mapping System for Superconducting Cavities at KEK -1
SUSP019   use link to see paper's listing under its alternate paper code  
 
  • T. Okada, E. Kako, T. Konomi, H. Sakai, K. Umemori
    Sokendai, Ibaraki, Japan
  • E. Kako, T. Konomi, M. Masuzawa, H. Sakai, K. Tsuchiya, R. Ueki, K. Umemori
    KEK, Ibaraki, Japan
  • A. Poudel, T. Tajima
    LANL, Los Alamos, New Mexico, USA
 
  A temperature and magnetic field mapping system for a single cell superconducting cavity is being developed at KEK. The mapping system is used to observe the temperature distribution and the ambient magnetic field distribution around the outer surface of the cavity. A total of 36 boards at every 10 degrees are attached on the cavity. Each board consists of 15 carbon resistors of 100 Ω at room temperature and 3 AMR sensors of X, Y and Z directions at the equator. The calibration of the resisters and AMR sensors were carefully and precisely carried out at low temperature. The data logging system using NI loggers is enabled to measure within 1 ms in the whole cavity surface. The initial test results in the vertical test of the single-cell cavity will be reported in this paper.  
 
TUP061 Gradients of 50 MV/m in TESLA Shaped Cavities via Modified Low Temperature Bake -1
 
  • D. Bafia, J. Zasadzinski
    IIT, Chicago, Illinois, USA
  • D. Bafia, A. Grassellino, O.S. Melnychuk, A.S. Romanenko, Z-H. Sung
    Fermilab, Batavia, Illinois, USA
 
  This paper will discuss the 75/120 C modified low temperature bake capable of giving unprecedented accel-erating gradients of above 50 MV/m for 1.3 GHz TESLA-shaped niobium SRF cavities in CW operation. A bifurca-tion in the Q0 vs Eacc curve is observed after retesting cavities without disassembly in between, yielding per-formance that ranges from exceptional to above state-of-the-art. Atomic Force Microscopy studies on cavity cut-outs gives a possible mechanism responsible for this branching in performance, namely, the dissociation and growth of room temperature niobium nano-hydrides that exist near the RF surface, which are made superconduct-ing only through the proximity effect. In-situ low temper-ature baking of cavity cutouts reveals a dissociation of these room temperature nano-hydrides, which could ex-plain the higher performance of cavities subject to similar in-situ heating in the dewar.  
 
TUP062 New Insights in the Quench Mechanisms in Nitrogen Doped Cavities -1
 
  • D. Bafia, J. Zasadzinski
    IIT, Chicago, Illinois, USA
  • D. Bafia, D.J. Bice, A. Grassellino, O.S. Melnychuk, A.S. Romanenko, D.A. Sergatskov
    Fermilab, Batavia, Illinois, USA
  • D. Gonnella
    SLAC, Menlo Park, California, USA
  • A.D. Palczewski
    JLab, Newport News, Virginia, USA
 
  This paper will cover a systematic study of the quench in nitrogen doped cavities: three cavities were sequentially treated/reset with different doping recipes which are known to produce different levels of quench field. Analysis of mean free path and TMAP coupled with sample analysis reveals new insights on the physics of the premature quench in nitrogen doped cavities; new recipes demonstrate the possibility to increase quench fields well beyond 30 MV/m.  
 
TUP063
Low Temperature Baking Study for High-gradient SRF Cavities at Cornell University  
 
  • M. Ge, T. Gruber, J.J. Kaufman, P.N. Koufalis, M. Liepe, J.T. Maniscalco
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Under certain conditions, low-temperature vacuum baking can significantly increase SRF accelerating gradients with high-quality factors. Such performance improvements would greatly benefit future accelerators. In this paper, we report latest results from high-gradient research at Cornell, which focuses on 75°C vacuum baking to improve maximum fields. We demonstrate that such low-temperature bakes can significantly improve quench fields in certain cases. We further report on high-pulsed power results of these cavities before and after baking.  
 
TUP064 Flashover on RF Window of HWR SRF Cavity -1
SUSP006   use link to see paper's listing under its alternate paper code  
 
  • X. Liu, Z. Gao, Y. He, G. Huang
    IMP/CAS, Lanzhou, People’s Republic of China
 
  Breakdown on the RF ceramic windows always happen in different kinds of accelerator. It is one of the main limitations in current day superconducting cavities and couplers. The PT signal trip caused by discharge on the surface of RF ceramic window lead LLRF control system trip which affect the stable operation of the superconducting linac. Simulation of field emission electron trajectory in superconducting cavity and experimental measurements of the frequency of the pickup signal trip have been performed. A lot of aged window with characteristics of flashover were studied by means of material characterization. The flashover on the surface of RF ceramic window caused by electrons and field emission provide the origin of initial electrons. A modified design of the pickup antenna have solved the PT pickup trip problem.  
 
TUP066 New Design of SSR2 Spoke Cavity for PIP II SRF Linac -1
 
  • P. Berrutti, I.V. Gonin, T.N. Khabiboulline, M. Parise, D. Passarelli, G.V. Romanov, F. Ruiu, A.I. Sukhanov, V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
 
  Funding: US Department of Energy
Superconducting SSR2 spoke cavities provide acceleration of the H in PIP II SRF linac from 35 to 185 MeV. The RF and mechanical design of the SSR2 cavities has been completed and satisfies the technical requirements. However, our resent results of the high RF power tests of fully dressed SSR1 cavities show considerably strong multipacting (MP), which took significant time to process. On the other hand, the new results of the tests of balloon cavity showed significant mitigation of MP. In this paper we present the results of the improved design of the SSR2 cavity, based on the balloon cavity concept. The electromagnetic design is presented, including RF parameter optimization, MP simulations, field asymmetry analysis, High Order Mode (HOM) calculations. Mechanical analysis of the dressed cavity is presented also, which includes Lorentz Force Detuning optimization, and reduction of the cavity resonance frequency sensitivity versus He pressure fluctuations. The design completely satisfies the PIP II technical requirements.
 
 
TUP067
Plasma Processing to Reduce Field Emission in LCLS-II 1.3 GHz SRF Cavities  
FRCAB7   use link to access more material from this paper's primary paper code  
SUSP022   use link to access more material from this paper's primary paper code  
 
  • B. Giaccone, J. Zasadzinski
    IIT, Chicago, Illinois, USA
  • P. Berrutti, B. Giaccone, A. Grassellino, M. Martinello
    Fermilab, Batavia, Illinois, USA
  • M. Doleans
    ORNL, Oak Ridge, Tennessee, USA
  • D. Gonnella, G. Lanza, M.C. Ross
    SLAC, Menlo Park, California, USA
 
  Plasma cleaning for LCLS-II 9-cell 1.3 GHz cavities is under study at Fermilab. Starting from ORNL method, we have developed a new technique for plasma ignition using HOMs. Plasma processing is being applied to contaminated and field emitting cavities, here are discussed the first results in terms of Q and radiation vs E measured before and after treatment. Further studies are ongoing to optimize plasma parameters and to acquire statistics on plasma cleaning effectiveness.  
slides icon Slides TUP067 [14.701 MB]  
 
TUP068 Study of Surface Treatment of 1.3 GHz Single-cell Copper Cavity for Niobium Sputtering -1
SUSP018   use link to see paper's listing under its alternate paper code  
 
  • F.Y. Yang, J. Dai, P. He, Z.Q. Li, Y. Ma, P. Zhang
    IHEP, Beijing, People’s Republic of China
 
  Funding: This work has been supported in part by PAPS project and National Key Programme for S&T Research and Development (Grant NO.: 2016YFA0400400)
A R&D program on niobium sputtering on copper cavities has started at IHEP in 2017. Single-cell 1.3 GHz copper cavity has been chosen as a substrate. A chemical polishing system has subsequently developed and commissioned recently to accommodate the etching of both copper samples and a cavity. Different polishing agents have been tested on copper samples and later characterized. The results of these surface treatment tests are presented.
 
poster icon Poster TUP068 [1.228 MB]  
 
TUP069
RF Behavior of ECR Nb/Cu Films  
 
  • A-M. Valente-Feliciano, C.E. Reece, J.K. Spradlin, O. Trofimova
    JLab, Newport News, Virginia, USA
  • C.Z. Antoine
    CEA-IRFU, Gif-sur-Yvette, France
  • M. Arzeo
    CERN, Geneva, Switzerland
  • Th. Proslier
    CEA-DRF-IRFU, France
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
The different processes involved in energetic condensation are exploited in electron cyclotron resonance (ECR) generated plasma deposition to tailor Nb film growth in sequential steps. The resulting Nb/Cu films display high quality material and show promise of high RF performance. In order to better understand the residual and flux induced surface resistance contributing factors, the RF performance of ECR Nb/Cu films is measured at different temperatures and frequencies in a quadrupole resonator (QPR). In parallel, film material and superconducting properties are evaluated with various microscopy and magnetometry techniques. This contribution presents the correlation of ECR Nb film material characteristics with RF performance with the objective to minimize RF losses in Nb/Cu films.
 
 
TUP070 The SRF Thin Film Test Facility in LHe-Free Cryostat -1
 
  • O.B. Malyshev, J.A. Conlon, P. Goudket, N. Pattalwar, S.M. Pattalwar
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • G. Burt
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • G. Burt
    Lancaster University, Lancaster, United Kingdom
 
  An ongoing programme of development superconducting thin film coating for SRF cavities requires a facility for a quick sample evaluation at the RF conditions. One of the key specifications is a simplicity of the testing procedure, allowing an easy installation and quick turnover of the testing samples. Choked test cavities operating at 7.8 GHz with three RF chokes have been designed and tested at DL in a LHe cryostat verifying that the system could perform as required. Having a sample and a cavity physically separate reduces the complexity involved in changing samples (major causes of low throughput rate and high running costs for other test cavities) and also allows direct measurement of the RF power dissipated in the sample via power calorimetry. However, changing a sample and preparation for a test requires about two-week effort per sample. In order to simplify the measurements and achieve a faster turnaround, a new cryostat cooled with a closed-cycle refrigerator has been designed, built and tested. Changing a sample, cooling down and testing can be reduced to 2-3 days per sample. Detailed design and results of testing of this facility will be reported at the conference.  
 
TUP072 The Development of Niobium Sputtering on Copper Cavities at IHEP -1
 
  • J. Dai, P. He, Z.Q. Li, Y. Ma, F.Y. Yang, P. Zhang
    IHEP, Beijing, People’s Republic of China
 
  A R&D program focusing on niobium sputtering on copper cavities started at IHEP in 2017. Single-cell 1.3 GHz elliptical cavity shape has been initially chosen as sputtering substrate. A magnetron sputtering system have been developed in 2018. In addition, a surface treatment facility to polish the copper substrate before sputtering has been developed and commissioned. This paper will present the Nb/Cu coating activities at IHEP.  
 
TUP073 Superconducting Thin Films Characterization at HZB with the Quadrupole Resonator -1
 
  • D.B. Tikhonov, S. Keckert, J. Knobloch, O. Kugeler, Y. Tamashevich
    HZB, Berlin, Germany
  • A-M. Valente-Feliciano
    JLab, Newport News, Virginia, USA
 
  Funding: EASITrain - European Advanced Superconductivity Innovation and Training. This Marie Sklodowska-Curie Action Innovative Training Networks founded by H2020 under Grant Agreement no. 764879
Superconducting thin films have great potential as post-Nb material for use in SRF applications in future accelerators and industry. To test the RF-performance of such films in practice, would require the building and coating of a full RF cavity. Deposition of thin films on such scales in test facilities are challenging, in particular when curved surfaces have to be coated. This greatly complicates their systematic research. In this contribution we report on the method we use to characterize small and flat thin film samples (Deposited onto both Nb and Cu substrates) in an actual cavity named the Quadrupole Resonator (QPR). We also summarize the latest measurement results of NbTiN thin films. The Quadrupole Resonator at HZB is a tool that is able to perform SRF characterizations at frequencies ~415, 847, 1300 MHz with RF fields using an RF-DC power compensation technique.
 
poster icon Poster TUP073 [2.318 MB]  
 
TUP074
Understanding Electrochemistry of Nb in Thin Film Deposition Process  
 
  • C.U. Kim, G. Ni
    University of Texas at Arlington, Arlington, USA
  • L.D. Cooley, P.J. Lee
    NHMFL, Tallahassee, Florida, USA
 
  Funding: This work was supported by the US Department of Energy under contract DE-SC0018379
We investigate whether the precursors for Nb3Sn coating on a seamless Cu superconducting radio-frequency cavity can be formed by electrochemical methods. Our primary interest is to use electroplating to create Nb and/or bronze layers in sequence on polished surfaces of Cu and induce growth of Nb3Sn superconducting layer via solid state diffusion. A few unsuccessful attempts have been reported for the plating Nb using non-aqueous electrolyte solution, motivating us to study the mechanism behind failures and find ways to overcome the very factors that have thwarted previous efforts. For this, we have studied the electrochemistry of Nb in a non-aqueous media, with a weighted emphasis on understanding the mechanism of plating inhibition. Our investigation, although partial, finds that both electro-plating and chemical-plating of Nb are possible in an organic solvent based electrolyte system. In this paper, we will discuss the electrochemistry of the Nb and also present ways to enable Nb coating via electrochemical routes.
 
 
TUP075
New Progress for Nb Sputtered 325 MHz QWR Cavities in IMP  
 
  • F. Pan, H. Guo, Y. He, T.C. Jiang, C.L. Li, M. Lu, T. Tan
    IMP/CAS, Lanzhou, People’s Republic of China
 
  Comparing with bulk niobium cavities, the Nb/Cu cavities feature a much better stability at 4.5 K. Last year, two 325 MHz QWR copper cavities coated with biased DC diode sputterred Nb for CiADS has been accomplished at IMP. But vertical tests showed the cavities had low Q0 at 4 K. To solve the issue, a new coating system was designed and built. The sputtering target was redesigned and manufactured. The coating parameters were selected again and auxiliary heating was used to control the coating temperature in the process of sputtering. The power and Ar pressure during coating were also carefully selected. The paper covers resulting film characters, vertical tests with the evolution of the sputtering process, and improvements we made since last year.  
 
TUP076 Electrochemical Deposition of Nb3Sn on the Surface of Cu Substrates -1
SUSP005   use link to see paper's listing under its alternate paper code  
 
  • M. Lu, Q.W. Chu, Y. He, Z.Q. Lin, F. Pan, T. Tan, Z.Q. Yang
    IMP/CAS, Lanzhou, People’s Republic of China
 
  Coating superconducting Nb3Sn thin film on the inner surface of a superconducting RF cavity is one of the most promising approaches to improve the performance of the accelerating cavity. Compared with traditional evaporation and sputtering, electrochemical coating has the advantages on process simplicity, low cost and mass production. However, the conventional electroplating, because of its low growth temperature and aqueous reaction environment, tends to produce porous, loosely bonded, and often contaminated film. All these properties result in excessive pinning center and deteriorate the superconducting radio frequency cavities performance. In this paper, a new method including multi-layer electroplating and heat treatment is used to deposit Nb3Sn thin film on top of copper substrates. Important growth parameters, e.g. electrical current density, layer thickness ratio, and annealing temperature are studied. The morphology of the film surfaces was observed by scanning electron microscope (SEM) and the structure of the film was analyzed by X-ray diffraction (XRD). The results showed that a flat and uniform Nb3Sn layer on copper can be obtained, and the thickness is about 7 micron.  
poster icon Poster TUP076 [0.716 MB]  
 
TUP077 Nb3Sn Thin Film Coating Method for Superconducting Multilayered Structure -1
 
  • R. Ito, T. Nagata
    ULVAC, Inc, Chiba, Japan
  • H. Hayano, R. Katayama, T. Kubo, T. Saeki
    KEK, Ibaraki, Japan
  • H. Ito
    Sokendai, Ibaraki, Japan
  • Y. Iwashita
    Kyoto ICR, Uji, Kyoto, Japan
 
  S-I-S (superconductor-insulator-superconductor) multilayered structure has been proposed in order to increase the maximum acceleration gradient of SRF cavities. Nb3Sn is the material most expected as a superconducting layer of the S-I-S multilayered structure because it offers both a large critical temperature and large predicted Hsh. Most important in fabricating Nb3Sn thin films is the stoichiometry of the material produced, and the lack of tin leads to performance degradation. We have launched a new in-house DC magnetron sputtering apparatus for Nb3Sn deposition. Nb and Sn layers were alternately and repeatedly deposited on Si wafer while adjusting the film thickness of each layer, so we successfully obtained Nb-Sn films having appropriate composition ratio. The as-deposited films were annealed under the temperature of 600 degree C for 1 hour to generate the Nb3Sn phase. The characteristics of Nb-Sn films evaluated by XRD, XRF, FE-SEM, and so on. We also measured critical temperature of the annealed films. In this paper, the detail of the Nb3Sn coating method and the measurement result of the Nb-Sn films will be reported.  
 
TUP078 Lower Critical Field Measurement of NbN Multilayer Thin Film Superconductor at KEK -1
SUSP013   use link to see paper's listing under its alternate paper code  
 
  • H. Ito
    Sokendai, Ibaraki, Japan
  • C.Z. Antoine
    CEA-IRFU, Gif-sur-Yvette, France
  • H. Hayano, R. Katayama, T. Kubo, T. Saeki
    KEK, Ibaraki, Japan
  • R. Ito, T. Nagata
    ULVAC, Inc, Chiba, Japan
  • Y. Iwashita, H. Tongu
    Kyoto ICR, Uji, Kyoto, Japan
 
  Funding: The work is supported by Japan Society for the Promotion of Science Grant-in-Aid for Young Scientist (A) No.17H04839.
The multilayer thin film structure of the superconductor has been proposed by A. Gurevich to enhance the maximum gradient of SRF cavities. The lower critical field Hc1 at which the vortex start penetrating the superconducting material will be improved by coating Nb with thin film superconductor such as NbN. It is expected that the enhancement of Hc1 depends on the thickness of each layer. In order to determine the optimum thickness of each layer and to compare the measurement results with the theoretical prediction proposed by T. Kubo, we developed the Hc1 measurement system using the third harmonic response of the applied AC magnetic field at KEK. For the Hc1 measurement without the influence of the edge or the shape effects, the AC magnetic field can be applied locally by the solenoid coil of 5mm diameter in our measurement system. ULVAC made the NbN-SiO2 multilayer thin film samples of various NbN thicknesses. In this report, the measurement result of the bulk Nb sample and NbN-SiO2 multilayer thin film samples of different thickness of NbN layer will be discussed.
 
 
TUP079 Deposition of Nb3Sn Films by Multilayer Sequential Sputtering for SRF Cavity Application -1
SUSP015   use link to see paper's listing under its alternate paper code  
 
  • Md.N. Sayeed, H. Elsayed-Ali
    ODU, Norfolk, Virginia, USA
  • M.C. Burton, G.V. Eremeev, C.E. Reece, A-M. Valente-Feliciano
    JLab, Newport News, Virginia, USA
  • U. Pudasaini
    The College of William and Mary, Williamsburg, Virginia, USA
 
  Nb3Sn is considered as an alternative of Nb for SRF accelerator cavity application due to its potential to obtain higher quality factors and higher accelerating gradients at a higher operating temperature. Magnetron sputtering is one of the effective techniques that can be used to fabricate Nb3Sn on SRF cavity surface. We report on the surface properties of Nb3Sn films fabricated by sputtering multiple layers of Nb and Sn on sapphire and niobium substrates followed by annealing at 950°C for 3 h. The crystal structure, film microstructure, composition and surface roughness were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and atomic force microscopy (AFM). The RF performance of the Nb3Sn coated Nb substrates were measured by a surface impedance characterization system. We also report on the design of a multilayer sputter deposition system to coat a single-cell SRF cavity.  
 
TUP080 Tuner Design and Test for 166.6 MHz SRF Cavity of HEPS -1
 
  • Z.H. Mi, Z.Q. Li, H.Y. Lin, W.M. Pan, Q.Y. Wang, P. Zhang, X.Y. Zhang, H.J. Zheng
    IHEP, Beijing, People’s Republic of China
 
  The 166.6 MHz superconducting RF cavities have been proposed for the High Energy Photon Source (HEPS), a 6 GeV kilometer-scale light source. The cavity is of quarter-wave type made of bulk niobium with ’=1. Each cavity will be operated at 4.2 K providing 1.2 MV accelerating. To compensate the frequency change due to manufacturing uncertainty, Lorentz force, beam loading, He pressure and microphonics the plunger tuner and gap tuner are chosen as options. Now the plunger tuner and low temperature gap tuner have been test with cavity, while the warm gap tuner is being designed. Details of the design and summary of the test results of the two type tuners with cavity are presented in this paper.  
poster icon Poster TUP080 [1.141 MB]  
 
TUP081 Status of the HL-LHC Crab Cavity Tuner -1
 
  • K. Artoos, L. Arnaudon, R. Calaga, E. Cano-Pleite, O. Capatina, T. Capelli, D.F. Cartaxo dos Santos, M. Garlaschè, D.C. Glenat, A. Krawczyk, R. Leuxe, P. Minginette, J.S. Swieszek
    CERN, Geneva, Switzerland
  • T.J. Jones
    STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
  • A. Krawczyk, B. Prochal
    IFJ-PAN, Kraków, Poland
  • J.A. Mitchell
    Lancaster University, Lancaster, United Kingdom
  • S. Verdú-Andrés
    BNL, Upton, Long Island, New York, USA
 
  Funding: Research supported by the HL-LHC project
The resonance frequency of the HL-LHC Double Quarter Wave (DQW) and Radio Frequency Dipole (RFD) crab cavities is set to the operating frequency of 400.79 MHz by deforming the cavities. For both types of cavities, the tuning principle foresees a symmetric mechanical deformation of parts of the cavities in vertical direction, with the tuner motor placed outside on top of the vacuum vessel. The tuner design was successfully tested on the DQW prototype cryomodule with two cavities in 2018 in the SPS at CERN. This paper describes the design of DQW and RFD crab tuners. The experience and results of assembly and cold testing is given together with some required improvements. Finally, the final series crab tuners preparation is reported.
 
 
TUP082
Active Microphonics Compensation Development at FNAL.  
 
  • W. Schappert, B.E. Chase, J. Einstein-Curtis, J.P. Holzbauer, Y.M. Pischalnikovpresenter
    Fermilab, Batavia, Illinois, USA
 
  Latest results in the development of techniques used to actively compensate microphonics for the narrow-bandwidth SRF cavities will be presented.  
poster icon Poster TUP082 [0.765 MB]  
 
TUP083 Performance of the 650 MHz SRF Cavity Tuner for PIP II Project -1
 
  • Y.M. Pischalnikov, S.K. Chandrasekaran, S. Cheban, I.V. Gonin, T.N. Khabiboulline, V.P. Yakovlev, J.C. Yun
    Fermilab, Batavia, Illinois, USA
  • C. Contreras-Martinez
    FRIB, East Lansing, Michigan, USA
 
  The PIP-II linac will include fifty seven 650MHz SRF cavities. Each cavity will be equipped with tuner for coarse and fine frequency tuning. Design and operations parameters will be discussed. Results from room temperature tests with prototype tuner installed on a 650MHz ’G=0.90 elliptical cavity will be presented.  
poster icon Poster TUP083 [1.567 MB]  
 
TUP084 Testing of the Piezo-actuators at High Dynamic Rate Operational Conditions -1
 
  • Y.M. Pischalnikov, J.C. Yun
    Fermilab, Batavia, Illinois, USA
  • C. Contreras-Martinez
    FRIB, East Lansing, Michigan, USA
 
  Reliability of the piezo-actuators that deployed into SRF cavity tuner and operated at high dynamic rate operational conditions made significant impact on the overall performance of the SRF linacs. We tested at FNAL piezo-actuators P-P-844K075 that were developed at Physik Instrumente for LCLS II project. Even these actuators were developed for CW linac we tested them at high dynamic rate inside cryogenic/insulated vacuum environment. Results of the tests will be presented. Different modes of the piezo-actuators failure will be discussed.  
poster icon Poster TUP084 [3.168 MB]  
 
TUP085 Operation of an SRF Cavity Tuner Submerged into Liquid He -1
 
  • Y.M. Pischalnikov, D.J. Bice, A. Grassellino, T.N. Khabiboulline, O.S. Melnychuk, R.V. Pilipenko, S. Posen, O.V. Pronitchev, A.S. Romanenko
    Fermilab, Batavia, Illinois, USA
 
  To precisely control the resonance of 1.3 GHz SRF cavities during testing at the FNAL’s Vertical Test Facility, we install for the first time a double lever tuner and operate it when submerged into the liquid He bath. Both active components of the tuner: electromechanical actuator (stepper motor) and piezo-actuators are operated inside superfluid helium. Accuracy in controlling the SRF cavity resonance frequency will be presented. Specifics of the tuner operation when submerged into liquid He will be discussed.  
poster icon Poster TUP085 [2.164 MB]  
 
TUP086 Frequency Tuning System Based on Mobile Plungers For Superconductive Coaxial Half Wave Resonators -1
 
  • D. Bychanok, S. Huseu, S.A. Maksimenko
    INP BSU, Minsk, Belarus
  • A.V. Butenko, E. Syresin
    JINR, Dubna, Moscow Region, Russia
  • E.A. Gurnevich
    Belarussian State University, Scientific Research Institute of Nuclear Problems, Minsk, Belarus
  • M. Gusarova, M.V. Lalayan, S.M. Polozov
    MEPhI, Moscow, Russia
 
  The design of a prototype of the frequency tuning system (FTS) for superconductive coaxial half wave cavities (HWR) [1] developed for the Nuclotron-based Ion Collider fAcility (NICA) injector is presented. The proposed system is based on mobile plungers placed in the technological holes in the end caps of the resonator. The FTS allows controlling the penetration depth of plungers, which is monotonically related to the resonant frequency shift of the cavity. The developed FTS includes slow/fast tuner parts and is more compact and simple in comparison to traditional mechanical systems, which deform reversibly the HWR by applying an effort on the beam ports [2]. The similar plunger-based tuner design was considered for QWR cavities in [3]. The results of numerical simulations of the resonant frequency for a wide range of plunger parameters are presented and discussed. The most important parameters for effective frequency shift are estimated.
[1] S. Matsievskiy et al., RuPAC’18. doi:10.18429/JACoW-RUPAC2018-WEPSB48
[2] N. Misiara et al., LINAC’16. doi:10.18429/JACoW-LINAC2016-MOPRC026
[3] D. Longuevergne et al., ‘‘A cold tuner system with mobile plunger’’, in Proc. SRF2013, paper THIOD04.
 
 
TUP087 Development and Performances of Spoke Cavity Tuner for MYRRHA Linac Project -1
 
  • N. Gandolfo, S. Blivet, P. Duchesne, D. Le Dréan
    IPN, Orsay, France
 
  In the framework of the Multi-purpose hYbrid Research Reactor for High-tech Applications (MYRRHA) 100 MeV linac construction, a fully equipped prototype cryomodule is being developed. In order to control the resonance frequency of the cavities during operation, a tuner has been studied with the specific requirements: high degree of reliability and high tuning speed. This paper reports the design consideration and the first performances measurement in vertical cryostat test at an early stage of the prototyping phase.  
poster icon Poster TUP087 [2.367 MB]  
 
TUP088
Vacuum Barrier Design of ADS Injector Helium Cryogenic System  
 
  • X. Wang
    IMP/CAS, Lanzhou, People’s Republic of China
 
  In helium cryogenic superconducting accelerator system, vacuum barrier is important equipment to isolate vacuum of different systems. At first, this paper briefly introduces ADS injector cryogenic system.then describes structure design of vacuum barrier after that thermal-stress coupled analysis model is established. We obtain temperature and stress distribution of different working conditions and verify the rationality of structure design. This design provides reference basis for optimization and similar design of large cryogenic system  
 
TUP089 FRIB LS1 Cryomodule’s Solenoid Commissioning -1
 
  • M. Xu, H. Ao, B. Bird, R. Bliton, C. Compton, J. Curtin, L. Hodges, K. Holland, S.J. Miller, K. Saitopresenter, T. Xu, C. Zhang
    FRIB, East Lansing, Michigan, USA
 
  Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661 and the National Science Foundation under Cooperative Agreement PHY-1102511.
The Facility for Rare Isotope Beams (FRIB) is a heavy ion accelerator that produces rare isotopes for science. To achieve the high beam quality of FRIB’s linear accelera-tor (linac), the superconducting solenoid packages are employed for beam focusing and steering in the cry-omodule. The solenoid packages will generate a maxi-mum 8T focusing field along beam direction and 0.124 T bending field for beam steering. A total 74 solenoid packages have been produced and the first segment linac (LS1) of FRIB have completed commissioning and beam acceleration. In this paper, the cryomodule’s solenoid commissioning and the performance of the LS1 linac are introduced. The lessons learned during the testing will also be presented.
 
 
TUP090
Performance of Quarter Wave Resonators in the FRIB Superconducting Driver Linear Accelerator  
 
  • S.H. Kim, F. Casagrande, W. Chang, V. Ganni, W. Hartung, P. Knudsen, H. Maniar, S.J. Miller, D.G. Morris, A.S. Plastun, J.T. Popielarski, H.T. Ren, K. Saitopresenter, M. Thrush, J. Wei, T. Xu, C. Zhang, S. Zhao
    FRIB, East Lansing, Michigan, USA
 
  Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661, the State of Michigan and Michigan State University.
All 15 Quarter-wave resonator (QWR) cryomodules for FRIB superconducting driver linear accelerator (linac), which consists of 12 β=0.041 QWRs and 92 β=0.085 QWRs, have been commissioned in the FRIB Linac Segment 1 (LS1). All cavities are excited to the accelerating gradients higher than the FRIB design and phase-locked to the FRIB master clock together with amplitude lock, operated at 4 K. We will present performance of the cavities, RF power couplers, and frequency tuners in the ’on-line’ cryomodule tests and the phased FRIB beam commissioning. We will also discuss the phase and amplitude stability of the cavity accelerating fields and the conditioning effects such as field emission and multipacting.
 
 
TUP091
Production Status of Superconducting Cryomodules for the Facility for Rare Isotope Beams  
 
  • C. Compton, H. Ao, J. Asciutto, B. Bird, W. Hartung, S.J. Miller, J.T. Popielarski, L. Popielarski, K. Saito, M. Shuptar, B.P. Tousignant, M. Xu
    FRIB, East Lansing, Michigan, USA
 
  Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661
The Facility for Rare Isotope Beams (FRIB) is a Superconducting Radio Frequency (SRF) accelerator project under construction at Michigan State University (MSU). The driver linac is designed with four cavity types (β = 0.041, 0.085, 0.29, and 0.53) and 6 different cryomodule designs. The FRIB Cryomodule Department has assembled 40 of 46 required cryomodules with 32 units tested and installed in the accelerator tunnel. Focus remains on the assembly, testing, and installation of the remaining cryomodules; scheduled to conclude by the end of 2019. A status on production rate, installation activities, and recent lessons learned will be presented.
 
 
TUP092
Experiences of Superconducting Radio Frequency Coldmass Production for the FRIB Linear Accelerator  
 
  • K. Elliott, L. Popielarskipresenter
    FRIB, East Lansing, Michigan, USA
 
  Funding: *Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661 and the National Science Foundation under Cooperative Agreement PHY-1102511.
The superconducting radio frequency (SRF) portion of the Facility for Rare Isotope Beams (FRIB) linear accelerator consists of 46 cryomodules of 6 different types. Each cryomodule contains a coldmass consisting of a string of SRF resonators. There are four different types of resonators; a β=0.041 quarter wavelength resonator (QWR), a β=0.085 QWR, a β=0.29 half wavelength resonator (HWR), and a β=0.53 HWR. In total there are 324 SRF resonators in the FRIB linear accelerator. This paper provides a summary of experiences from the assembly of all FRIB coldmass types in a clean room environment.
 
poster icon Poster TUP092 [1.481 MB]  
 
TUP093 Summary of FRIB Cavity Processing in the SRF Coldmass Processing Facility and Lessons Learned -1
 
  • E.S. Metzgar, B.W. Barker, K. Elliott, W. Hartung, L. Popielarskipresenter, G.V. Simpson, D.R. Victory, J.D. Whaley
    FRIB, East Lansing, Michigan, USA
 
  Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661 and the National Science Foundation under Cooperative Agreement PHY-1102511.
Baseline coldmass production for the linear particle accelerator at the Facility for Rare Isotope Beams (FRIB) is nearing completion. This paper will review the processing of cavities through the FRIB superconducting radio frequency (SRF) coldmass production facility focusing on chemical processing and high-pressure rinsing. Key processing data will be compiled and correlations between processing variables and cavity RF testing results will be examined.
 
 
TUP094 Improvements to LCLS-II Cryomodule Transportation -1
 
  • N.A. Huque, E. Daly, P.D. Owen
    JLab, Newport News, Virginia, USA
  • B.D. Hartsell, J.P. Holzbauer
    Fermilab, Batavia, Illinois, USA
 
  The Linear Coherent Light Source (LCLS-II) is currently being constructed at the SLAC National Laboratory. A total of 35 cryomodules will be fabricated at Jefferson Lab (JLab) in Virginia and Fermi National Laboratory (FNAL) in Illinois and transported via road to SLAC. A shipping frame with an inner bed isolated by springs was designed to protect the CMs from shocks and vibrations during shipments. Successful road testing of the JLab prototype paved the way for production CM shipments. The initial production shipments lead to several catastrophic failures in beamline vacuum in the cryomodules. The failures were determined to be due to fatigue in Fundamental Power Coupler (FPC) bellows due to excessive motion during shipment. A series of instrumented CM shipping tests and component tests were undertaken to develop a solution. A modified spring layout was tested and implemented, which reduced shocks on the CMs. FPC coupler bellows restraints were tested on a shaker table and on a CM during shipping; they were able to reduce bellows motion by a factor of three. The updated shipping system is currently in use and has successfully delivered six cryomodules to SLAC from JLab and FNAL.  
poster icon Poster TUP094 [0.958 MB]  
 
TUP095 Lessons Learned Assembling the SSR1 Cavities String for PIP-II -1
 
  • D. Passarelli, D.J. Bice, M. Parise, T.J. Ring, G. Wu
    Fermilab, Batavia, Illinois, USA
  • S. Berry
    CEA-DRF-IRFU, France
 
  The string assembly of the prototype Single Spoke Resonator type 1 (SSR1) cryomodule for PIP-II at Fermilab was successfully completed. Lessons learned from the preparation, assembly and the quality control activities of the final fully integrated assembly will be presented.  
 
TUP096 Optimization of Clean Room Infrastructure and Procedure During LCLS-II Cryomodule Production at Fermilab -1
 
  • G. Wu, S.D. Adams, T.T. Arkan, M.A. Battistoni, D.J. Bicepresenter, M.B. Chlebek, E.R. Harms, B.M. Kuhn, A.M. Rowe
    Fermilab, Batavia, Illinois, USA
  • S. Berry, O. Napoly
    CEA-DRF-IRFU, France
 
  Funding: The work is supported by Fermilab which is operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
Optimization of Fermilab string assembly procedure and infrastructure has yielded a significant improvement of cryomodule particulate counts. Late production of LCLS-II cryomodules were tested at CMTF at Fermilab and showed little to no x-ray up to administrative limit. The paper describes the field emission measurement instrumentation, field emission results of LCLS-II cyomodules, clean room infrastructure upgrade and procedure optimization.
 
 
TUP098 Preparation for the Advanced Demonstrator Testing at GSI -1
 
  • V. Gettmann, K. Aulenbacher, W.A. Barth, F.D. Dziuba, M. Heilmann, T. Kürzeder, S. Lauber, J. List, M. Miski-Oglu, S. Yaramyshev
    GSI, Darmstadt, Germany
  • K. Aulenbacher, W.A. Barth, F.D. Dziuba, T. Kürzeder, S. Lauber, J. List, M. Miski-Oglu
    HIM, Mainz, Germany
  • K. Aulenbacher, F.D. Dziuba, S. Lauber
    IKP, Mainz, Germany
  • M. Basten, H. Podlech, M. Schwarz
    IAP, Frankfurt am Main, Germany
 
  The superconducting (sc) heavy ion Helmholtz Linear Accelerator (HELIAC) is under development at GSI. As a first step, the cw-Linac demonstrator was the first part for the proposed cw-LINAC@GSI. A superconducting CH-cavity, embedded by two superconducting solenoids has been tested with beam in 2017/2018 successfully. The sc CH-structure, designed at Goethe-University of Frankfurt, is the key component and offers a variety of research and development. As a next step the first cryostat of the HELIAC, the so called Advanced Demonstrator will be tested in the same testing environment at GSI. Therefore, a bigger concrete Bunker as well as the connection to the cryo plant is under development. The cold string was assembled in a rehabilitated clean room at GSI. For future clean room assemblies a fully equipped clean room is under preparation at Helmholtz-Institut Mainz. The mechanical suspension, composed of hanging components on crossed steel ropes, is a reliable concept to prevent the displacement during cool down. The cryogenic systems as well as all other mechanical tasks were solved. These and the future Advanced Demonstrator preparation will be presented.  
 
TUP099 Particulate Sampling and Analysis During Refurbishment of Prototype European XFEL Cryomodule -1
 
  • N. Krupka, C. Bate, D. Reschke, S. Saegebarth, M. Schalwat, P. Schilling, S. Sievers
    DESY, Hamburg, Germany
 
  Funding: This work was supported by the Helmholtz Association within the topic Accelerator Research and Development (ARD) of the Matter and Tech-nologies (MT) Program.
The cryomodule PXFEL31 is one of three prototype cryomodules for the European XFEL. In preparation of the series module assembly it was used for the qualification of infrastructure and personnel at CEA Saclay. After transport and tests at DESY the cryomodule was stored for several years. Last year we decided to refurbish this module with new cavities for the installation in the FLASH accelerator. During the disassembly of the cavity string in the clean room at DESY we took several particulate samples for analysis. Optical and laser optical microscopy give us an insight on the quantity and type of the particulates. We expect to get hints where the particulates come from and how they are transported through the cavity string during transport and operation.
 
poster icon Poster TUP099 [2.599 MB]  
 
TUP100 Thermal Load Studies on the Photocathode Insert with Exchangeable Plug for the BERLinPro SRF-Photoinjector -1
SUSP039   use link to see paper's listing under its alternate paper code  
 
  • J. Kühn, N. Al-Saokalpresenter, M. Bürger, M. Dirsat, A. Frahm, A. Jankowiak, T. Kamps, G. Klemz, S. Mistry, A. Neumann, H. Plötz
    HZB, Berlin, Germany
 
  For the operation of an SRF photoinjector a well-functioning and efficient cooling system of the photocathode is necessary. A test experiment was set up of the photocathode cooling system based on the original components, which we call thermal contact experiment (TCX). We present the results of our thermal load studies on the photocathode insert with exchangeable photocathode plug. The goal was to test all components before they are installed in the cold string of the BERLinPro SRF-Photoinjector to ensure the operation of very sensitive semiconductor photocathodes. The tests include the investigation of the cooling performance, the thermal load management and the mechanical stability of the photocathode insert.  
 
TUP101 LCLS-II Cryomodules Production Experience and Lessons Learned at Fermilab -1
 
  • T.T. Arkan, J.N. Blowers, C.M. Ginsburg, C.J. Grimm, J.A. Kaluzny, T.H. Nicol, Y.O. Orlov, K.S. Premo, R.P. Stanek, G. Wu
    Fermilab, Batavia, Illinois, USA
 
  LCLS-II is a planned upgrade project for the linear coherent light source (LCLS) at SLAC. The LCLS-II Linac will consist of thirty-five 1.3 GHz and two 3.9 GHz superconducting RF continuous wave (CW) cryomodules that Fermilab and Jefferson Lab are currently producing in collaboration with SLAC. The LCLS-II 1.3 GHz cryomodule design is based on the European XFEL pulsed-mode cryomodule design with modifications needed for CW operation. Two prototype cryomodules had been assembled and tested. After prototype cryomodule tests, both laboratories have increased their cryomodule production rate to meet the challenging LCLS-II project installation schedule requirements of approximately one cryomodule per month per laboratory. To date, Fermilab has completed the assembly and testing of sixteen 1.3 GHz cryomodules. Fermilab has successfully shipped five CMs to SLAC and will continue to ship with a two-week throughput. The first 3.9 GHz cryomodule assembly is scheduled to start in June 2019; production readiness verifications are in progress. This paper presents LCLS-II cryomodule assembly and production experience, emphasizing the challenges, the mitigations and lessons learned  
poster icon Poster TUP101 [0.834 MB]  
 
TUP102 Superconducting Harmonic Cavity for Bunch Lengthening in the APS Upgrade -1
 
  • M.P. Kelly, Z.A. Conway, M. Kedzie, S.W.T. MacDonald, T. Reid, U. Wienands, G.P. Zinkann
    ANL, Argonne, Illinois, USA
 
  A superconducting cavity based Bunch Lengthening System is under construction for the Argonne’s Advanced Photon Source (APS) Upgrade. The system will reduce the undesirable effects of Touschek scattering on the beam lifetime by providing bunch lengthening in the longitudinal direction by 2-4 times. The major technical components for the beam-driven 1.4 GHz fourth harmonic superconducting cryomodule are in hand and have been tested. These include a superconducting cavity, cw rf power couplers, a pneumatic cavity slow tuner and beamline higher-order mode absorbers. Initial assembly and engineering testing of the cryomodule is underway. Final integrated testing will be complete in 2021. Transportation to and commissioning in the APS is planned for 2022-23.  
 
TUP103 Pansophy Data as Used to Develop Metrics and Evaluate Trends Across SRF Projects and Facilities to Further Quality Improvement Initiatives -1
 
  • M.G. McDonald, V.D. Bookwalter, M. Dickey, E.A. McEwen
    JLab, Newport News, Virginia, USA
 
  Pansophy, a JLAB SRF engineering data management system (EDMS), is composed of a collection of technolo-gies that together provide for the collection, management and analysis of data for the production and testing of cavities and cryomodules. From its inception in 2000, when data collection was a priority for such projects as SNS, CEBAF 12GeV upgrade, LCLS-II, and in the future the SNS-PPU, the focus has turned to data analysis and reporting on quality metrics and key performance indica-tors (KPIs). Reporting enhancements include monthly quality metrics, project specific KPIs, and trending across projects. With the use of Pareto Charts to help analyze vendor quality and non-conformance, timelines of pro-ject and facility metrics, project managers and subject matter experts (SME) are able to look for trends and pre-pare further quality improvement initiatives for their projects.  
 
TUP104 Improvement of a Clean Assembly Work for Superconducting RF Cryomodule and Its Application to the KEK-STF Cryomodule -1
 
  • H. Sakai, E. Kako, T. Konomi, K. Umemori, Y. Yamamoto
    KEK, Ibaraki, Japan
  • T. Ebisawa, A. Kasugai
    QST, Aomori, Japan
 
  We usually encountered the degradation of the superconducting RF cavities on the cryomodule test even though the performance of these cavities was good on the vertical test. In reality, the degradation of Q-values of two cavities of cERL main-linac were observed after cryomodule assembly in KEK [1] and STF cryomodule also met the degradation after the cryomodule assembly [2]. Some dusts and invisible particles might enter the cavity and generate field emission during the assembly work. Field emission is the most important cause of this degradation. In this paper, first we introduce some trials for the improved clean assembly work to SRF cavity by re-examining our clean assembly work and vacuum work. For example, slow pumping system with vacuum particle monitor was developed to know and control the particle movement during slow pumping and venting. Next we show the application of this improved work to the STF re-assemble cryomodule work in KEK.
[1} H. Sakai et al., SRF’13, Paris, France, p.855, 2013.
[2] Y. Yamamoto et al., IPAC’16, Busan, Korea, p.2158, 2016.
 
 
TUP105 Preparation of the Cryomodule Assembly for the Linear IFMIF Prototype Accelerator (LIPAc) in Rokkasho -1
 
  • T. Ebisawa, A. Kasugai, K. Kondo, S. Maebara, K. Sakamoto
    QST, Aomori, Japan
  • N. Bazin, S. Berry
    CEA-DRF-IRFU, France
  • P. Cara
    IFMIF/EVEDA, Rokkasho, Japan
  • H. Dzitko, G. Phillips
    F4E, Germany
  • E. Kako, H. Sakai, K. Umemori
    KEK, Ibaraki, Japan
 
  The staged installation and commissioning of LIPAc is ongoing at Rokkasho Fusion Institute of QST, Japan for validating the low energy section of the IFMIF deuteron accelerator up to 9 MeV. The LIPAc Superconducting Radio Frequency accelerator (SRF) cryomodule is assembled under the responsibility of the EU Home Team, and the assembly work recently started at Rokkasho in March 2019. To fulfil the cleanliness requirements for the assembly process, QST took the responsibility to prepare the infrastructure of a cleanroom and associated devices. In this present paper, the details of the preparation work for the cryomodule assembly made by QST will be presented.  
poster icon Poster TUP105 [2.116 MB]  
 
TUP106 Mechanical Tuner for a 325 MHz Balloon Single Spoke Resonator -1
 
  • R.E. Laxdal, J.J. Keir, B. Matheson, N. Muller, Z.Y. Yao
    TRIUMF, Vancouver, Canada
 
  TRIUMF has designed, fabricated and tested the first balloon variant of the single spoke resonator at 325 MHz and β=0.3. TRIUMF has also designed and built a mechanical tuner as part of the development. The tuner employs a nutcracker lever pressing at the beam ports driven by a scissor jack. The scissor is actuated through a tube coupling to a warm ball-screw and servo-motor located outside the cryostat. The design and warm tests of the tuner will be presented.  
poster icon Poster TUP106 [1.089 MB]