Keyword: SRF
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MO1A01 The FRIB Superconducting Linac - Status and Plans cryomodule, ion, linac, cryogenics 1
 
  • J. Wei, H. Ao, S. Beher, N.K. Bultman, F. Casagrande, C. Compton, L.R. Dalesio, K.D. Davidson, A. Facco, F. Feyzi, V. Ganni, A. Ganshyn, P.E. Gibson, T. Glasmacher, W. Hartung, L. Hodges, L.T. Hoff, H.-C. Hseuh, A. Hussain, M. Ikegami, S. Jones, K. Kranz, R.E. Laxdal, S.M. Lidia, G. Machicoane, F. Marti, S.J. Miller, D.G. Morris, A.C. Morton, J.A. Nolen, P.N. Ostroumov, J.T. Popielarski, L. Popielarski, G. Pozdeyev, T. Russo, K. Saito, G. Shen, S. Stanley, H. Tatsumoto, T. Xu, Y. Yamazaki
    FRIB, East Lansing, USA
  • K. Dixon, M. Wiseman
    JLab, Newport News, Virginia, USA
  • A. Facco
    INFN/LNL, Legnaro (PD), Italy
  • K. Hosoyama
    KEK, Ibaraki, Japan
  • H.-C. Hseuh
    BNL, Upton, Long Island, New York, USA
  • M.P. Kelly, J.A. Nolen
    ANL, Argonne, Illinois, USA
  • R.E. Laxdal
    TRIUMF, Vancouver, Canada
 
  With an average beam power two orders of magnitude higher than operating heavy-ion facilities, the Facility for Rare Isotope Beams (FRIB) stands at the power frontier of the accelerator family. This report summarizes the current design and construction status as well as plans for commissioning, operations and upgrades.
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.
 
slides icon Slides MO1A01 [48.813 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MO1A01  
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MOPRC026 Mechanical Design of the HWR Cavities for the SARAF SRF LINAC cavity, linac, simulation, cryomodule 126
 
  • N. Misiara, L. Boudjaoui, G. Ferrand, P. Hardy, F. Leseigneur, C. Madec, N. Pichoff
    CEA/IRFU, Gif-sur-Yvette, France
 
  SNRC and CEA collaborate to the upgrade of the SARAF accelerator to 5 mA CW 40 MeV deuteron and proton beams (Phase 2). CEA is in charge of the design, construction and commissioning of the superconducting linac (SARAF-LINAC Project). The SCL consists in 4 cryomodules. The first two identical cryomodules host 6 half-wave resonator (HWR) low beta cavities (β = 0.09) at 176 MHz. The last two identical cryomodules will host 7 HWR high-beta cavities (β = 0.18) at 176 MHz. The fully equipped cavity includes the niobium cavity with its helium tank, the couplers and the frequency tuning system. In this paper, the mechanical design and the foreseen qualification procedures for both cavities and tuning systems are presented with compliance, to the best extent, to the rules of Unfired Pressure Vessels NF-EN 13445 (1-5) standards.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPRC026  
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MOPRC027 Surface Roughness Effect on the Performance of Nb3Sn Cavities cavity, pulsed-power, niobium, klystron 129
 
  • R.D. Porter, D.L. Hall, M. Liepe, J.T. Maniscalco
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Funding: DOE award DE-SC0008431
Surface roughness of current Niobium-3 Tin (Nb3Sn) superconducting radio-frequency (SRF) accelerator cavities can cause enhancement of the surface magnetic field. This enhancement can push the surface magnetic field beyond the critical field, which, if it occurs over a large enough area, can cause the cavity to quench. This paper presents simulations of the surface magnetic field enhancements in SRF cavities caused by the surface roughness of current Cornell Nb3Sn cavities, which have achieved record efficiency. Simple, smooth cavity geometry is defined and surface magnetic fields calculated using SLANS2. The cavity geometry is modified with a small rough region for which the geometry is determined from AFM scans of a Nb3Sn coated sample and the surface fields are calculated again. The calculated surface fields of the smooth and rough cavities are compared to determine the extent of the field enhancement, the area over which the enhancement is significant, and which surface features cause large field enhancement. We find that 1% of the surface analyzed has fields enhance by more than 45%. On average the Q-factor is increased by (3.8 ± 1.0) \%.
 
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MOPLR010 4 K SRF Operation of the 10 MeV CEBAF Photo-Injector cryomodule, operation, cavity, cryogenics 155
 
  • G.V. Eremeev, M.A. Drury, J.M. Grames, R. Kazimi, M. Poelker, J.P. Preble, R. Suleiman, Y.W. Wang, M. Wright
    JLab, Newport News, Virginia, USA
 
  Funding: Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
SRF accelerating cavities are often operated in superfluid helium of temperature near 2 K to enhance the cavity quality factor Q0 and manage cryogenic heat loads, which are particularly important at large SRF accelerator facilities. This temperature paradigm, however, need not put SRF technology out of the reach of small institutions or even limit SRF operation at large facilities to provide 10-100 MeV beam energy. At the Jefferson Lab CEBAF accelerator there are regularly scheduled maintenance periods during which the liquid helium temperature is raised to 4 K, reducing cryogenic plant power consumption by ~50% and saving megawatts of electrical power. During such a recent period, we accelerated a continuous-wave electron beam at the CEBAF photo-injector to 6.3 MeV/c with current ~80μA using two niobium cavities at helium temperature of 4 K. This contribution describes the SRF and cryogenic performance and uses measured beam quality and energy stability as key metrics. These measurements indicate that 4 K operation of niobium SRF cavities in CEBAF and at small institutions may be a sensible and cost effective mode of operation, provided the cryogenic load associated with lower Q0 is manageable for the number of SRF cavities needed. For Jefferson Lab, this enhances our scientific reach allowing additional low-energy ~10 MeV experiments each year.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR010  
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MOPLR020 Challenges in Realizing the LCLS-II Cryomodule Production cryomodule, cavity, linac, superconducting-RF 181
 
  • A. Burrill
    SLAC, Menlo Park, California, USA
 
  The LCLS-II project requires the assembly and installation of 37 cryomodules in order to deliver a 4 GeV electron beam to the undulators to produce both soft and hard x-rays at a repetition rate up to 1 MHz. All of the cryomodules will operate in continuous wave mode, with 35 operating at 1.3 GHz for acceleration and 2 operating at 3.9 GHz to linearize the longitudinal beam profile. One of the challenges of this project, and the topic of this paper, is coordinating the effort of three DOE labs in order to realize this machine in just a few years time. This coordination is necessary due to the fact that the cryomodules will be assembled at both Jefferson Lab and Fermi Lab, tested, and then shipped to SLAC for installation, commissioning and operation. This paper will report on our experiences to date, issues that have been identified and planned mitigation going forward.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR020  
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MOPLR023 Examination of Cutouts Inner Surfaces from Nb3Sn Coated Cavity cavity, niobium, ion, accelerating-gradient 189
 
  • U. Pudasaini, M.J. Kelley
    The College of William and Mary, Williamsburg, Virginia, USA
  • G.V. Eremeev, C.E. Reece
    JLab, Newport News, Virginia, USA
  • J. Tuggle
    Virginia Polytechnic Institute and State University, Blacksburg, USA
 
  Funding: Supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177 and Office of High Energy Physics under grant SC00144475.
The potential for higher operating temperature and higher gradient have motivated SRF cavity researchers to pursue Nb3Sn as an alternative to Nb for nearly fifty years. Far and away the most common embodiment has been a few micron-thick Nb3Sn layer on the cavity interior surface obtained by vapor diffusion coating, with one or another set of parameters. While many cavities have been made and RF tested, reports of dissecting a cavity in detail to examine the coating and relate it to RF measurements are rare. We coated a BCP-treated single cell cavity in a typical process of tin/tin chloride activation at 500 C followed by tin vapor deposition at 1200 C. After RF-testing, we cut and examined sections from several locations to learn composition, thickness topography of the interior surface. The effect of process variables, such as surface preparation, process temperature and duration, and vapor chemistry needs to be explored.
 
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MOPLR025 Investigation of Low-Level Nitrogen in Niobium by Secondary Ion Mass Spectrometry ion, niobium, cavity, factory 196
 
  • J. Tuggle
    Virginia Polytechnic Institute and State University, Blacksburg, USA
  • M.J. Kelley
    The College of William and Mary, Williamsburg, Virginia, USA
  • A.D. Palczewski, C.E. Reece
    JLab, Newport News, Virginia, USA
  • F.A. Stevie
    NCSU AIF, Raleigh, North Carolina, USA
 
  Funding: Supported by the U.S. DOE Office of Science, ONP contract DE-AC05-06OR23177 and OHEP grant SC00144475. Tuggle is supported by Nanoscale Characterization and Fabrication Laboratory at Virginia Tech.
Understanding the improvement of the SRF cavity quality factor by low-level nitrogen addition ("N-doping") is attracting much attention from researchers. Precise, repeatable measurement of the nitrogen profile in the parts-per-thousand to parts-per-million range is vital. Secondary Ion Mass Spectrometry (SIMS) is the approach of choice because of excellent sensitivity and depth resolution. Accurate quantitation must consider sample properties, such as surface topography and crystal structure, calibration of the instrument with reference materials, and data analysis. We report the results of a SIMS study in which polycrystal and single crystal coupons were N-doped, each accompanied by new SRF-grade niobium sheet equivalent to a single cell cavity.
 
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MOPLR026 Material Qualification of LCLS-II Production Niobium Material Including RF and Flux Expulsion Measurements on Single Cell Cavities cavity, niobium, cryomodule, controls 199
 
  • A.D. Palczewski, F. Marhauser
    JLab, Newport News, Virginia, USA
  • A. Grassellino, S. Posen
    Fermilab, Batavia, Illinois, USA
 
  Funding: Work at JLab is supported by the U.S. Department of Energy under contract DE-AC05-06OR23177 and Fermilab is operated by Fermi Research Alliance, LLC under Contract No. De-AC02-07CH11359.
It has been shown that cooldown details through transition temperature can significantly affect the amount of trapped magnetic flux in SRF cavities, which can lead to performance degradation proportional to the magnitude of the ambient magnetic field.[*] It has also more recently been shown that depending on the exact material properties - even when the material used originated from the same batch from the same vendor - and subsequent heat treatment, the percent of flux trapped during a cool-down could vary widely for identical cool-down parameters.[**] For LCLS-II, two material vendors have produced half of the niobium used for the cavity cells (Tokyo Denkai Co., Ltd. (TD) and Ningxia Orient Tantalum Industry Co., Ltd. (NX)). Both vendors delivered material well within specifications set out by the project (according to ASTM B 393-05), which allows yet some variation of material characteristics such as grain size and defect density. In this contribution, we present RF and magnetic flux expulsion measurements of four single cell cavities made out of two different niobium batches from each of the two LCLS-II material suppliers and draw conclusions on potential correlations of flux expulsion capability with material parameters. We present observations of limited flux expulsion in cavities made from the production material and treated with the baseline LCLS-II recipe.
[*] A. Romanenko et al J. Appl. Phys. 115, 184903 (2014)
[**] S. Posenet et al., Journal of Applied Physics 119, 213903 (2016).
 
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MOPLR032 Preparation for Cavity Material Studies at the Vertical High-Temperature UHV-Furnace of the S-DALINAC vacuum, niobium, simulation, superconductivity 209
 
  • R. Grewe, L. Alff, J. Conrad, T. Kürzeder, M. Major, N. Pietralla
    TU Darmstadt, Darmstadt, Germany
  • F. Hug
    IKP, Mainz, Germany
 
  Funding: Work supported by the Federal Ministry of Education and Research through grant No. 05H15RDRBA.
Since 2005 the Institute for Nuclear Physics at the Technische Universität Darmstadt operates a high temperature vacuum furnace. It is designed to reach temperatures of up to 1800°C. It has been used for baking out several niobium superconducting RF cavities at 850°C with proven success*. Current research for improving the performance of SRF cavities is focused on nitrogen treatment of such cavities. Nitrogen doping of SRF cavtities results in an up to four times higher quality-factor as compared to untreated cavities**. At higher temperatures between 1300°C and 1700°C the so-called delta-phase of NbN forms, which is highly interesting for applications to superconducting accelerator technology***. The UHV-furnace at the S-DALINAC offers the possibility to treat niobium samples at considerably higher temperatures than what has been done up to now in order to study the effect of delta-phase NbN and N-doping on superconducting properties. The furnace has been refurbished and recommissioned to realize research on nitrogen treatment of niobium samples. We will report on our first experiences with operating the upgraded furnace.
*Araz et al., Proceedings of SRF05, 2015
**Grasselino et al., Superconducting Science and Technology, 2013
***Pham Tu et al., Proceedings of SRF87, 1987
 
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MOPLR038 Fabrication of 9 Cell Coupon Cavity for Vertical Electropolishing Test cavity, cathode, polarization, controls 220
 
  • S. Kato, H. Hayano, H. Inoue, H. Monjushiro, T. Saeki, M. Sawabe
    KEK, Ibaraki, Japan
  • V. Chouhan, Y.I. Ida, K.N. Nii, T.Y. Yamaguchi
    MGH, Hyogo-ken, Japan
 
  We have been using single cell coupon cavities to establish vertical electropolishing (VEP) process for a couple of years. A series of in-situ measurements of an EP current at an individual coupon in a coupon cavity can help determination of appropriate EP conditions. VEPed coupons which are surface analysed with XPS, SEM and the other tools can also bring lot information and expertise to development of VEP cathode and optimization of VEP conditions. This time we fabricated the world first 9-cell coupon cavity where 3 sample coupons at the equators and 6 sample coupons at positions close to the irises can be installed. VEP of this coupon cavity with a newly developed Ninja cathode brought useful information for improvement of the VEP facility and optimization of the VEP conditions.  
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MOPLR043 Cavity Processing and Preparation of 650 MHz Elliptical Cell Cavities for PIP-II cavity, vacuum, factory, cathode 229
 
  • A.M. Rowe, S.K. Chandrasekaran, A. Grassellino, O.S. Melnychuk, M. Merio, D.A. Sergatskov
    Fermilab, Batavia, Illinois, USA
  • T. Reid
    ANL, Argonne, Illinois, USA
 
  Funding: Operated by Fermi Research Alliance, LLC under Contract No. De-AC02-07CH11359 with the United States Department of Energy.
The PIP-II project at Fermilab requires fifteen 650 MHz SRF cryomodules as part of the 800 MeV LINAC that will provide a high intensity proton beam to the Fermilab neutrino program. A total of fifty-seven high-performance SRF cavities will populate the cryomodules and will operate in both pulsed and continuous wave modes. These cavities will be processed and prepared for performance testing utilizing adapted cavity processing infrastructure already in place at Fermilab and Argonne. The processing recipes implemented for these structures will incorporate state-of-the art processing and cleaning techniques developed for 1.3 GHz SRF cavities for the ILC, XFEL, and LCLS-II projects. This paper describes the details of the processing recipes and associated chemistry, heat treatment, and cleanroom processes at the Fermilab and Argonne cavity processing facilities. This paper also presents single and multi-cell cavity test results with quality factors above 5·1010 and accelerating gradients above 30 MV/m.
 
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MOPLR047 Advanced Vertical Electro-Polishing studies at Cornell with Faraday cavity, niobium, status, target 233
 
  • F. Furuta, M. Ge, T. Gruber, G.H. Hoffstaetter, J.J. Kaufman, M. Liepe, J. Sears
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • T.D. Hall, M.E. Inman, S.T. Snyder, E.J. Taylor
    Faraday Technology, Inc., Clayton, Ohio, USA
 
  Cornell's SRF group and Faraday Technology Inc. have started collaborations on two phase-II SBIR projects. Both projects are aiming for the development of advanced Vertical Electro-Polishing (VEP) for Nb SRF cavities, such as HF free or acid free VEP protocols. These could be eco-friendlier alternatives for the standard, HF-based EP electrolyte used, and could bring new breakthrough performance for Nb SRF cavities. Here we give a status update and report first results from these two projects.  
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MOP106021 Superconducting Traveling Wave Cavity Tuning Studies cavity, accelerating-gradient, feedback, acceleration 327
 
  • R.A. Kostin
    LETI, Saint-Petersburg, Russia
  • P.V. Avrakhov, A. Kanareykin
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • N. Solyak, V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
 
  Funding: Work supported by US DOE SBIR # DE-SC0006300
Superconducting traveling wave cavity (SCTW) can provide 1.2-1.4 times larger accelerating gradient than conventional standing wave SRF cavities [1]. Firstly, traveling wave opens the way to use other than Pi-mode phase advance per cell which increase transit time factor. Secondly, traveling wave is not so sensitive to cavity length as standing wave, which length is limited to 1 meter because of field flatness degradation. 3 cell SCTW cavity was proposed [2] and built for high gradient traveling wave demonstration and tuning studies. This paper describes analytical model that was used for cavity development. Tuning properties and requirements are also discussed.
' r.kostin@euclidtechlabs.com
 
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TU2A03 Resonance Control for Future Linear Accelerators cavity, controls, resonance, electron 363
 
  • W. Schappert
    Fermilab, Batavia, Illinois, USA
 
  Many of the next generation of particle accelerators (LCLS II, PIP II) are designed for relatively low beam loading. Low beam loading requirement means the cavities can operate with narrow bandwidths, minimizing capital and base operational costs of the RF power system. With such narrow bandwidths, however, cavity detuning from microphonics or dynamic Lorentz Force Detuning becomes a significant factor, and in some cases can significantly increase both the acquisition cost and the operational cost of the machine. In addition to the efforts to passive environmental detuning reduction (microphonics) active resonance control for the SRF cavities for next generation linear machine will be required. State of the art in the field of the SRF Cavity active resonance control and the results from the recent efforts at FNAL will be presented in this talk.  
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TU3A01 Beam Commissioning Results From the R&D ERL at BNL gun, cathode, laser, cavity 374
 
  • D. Kayran, Z. Altinbas, D.R. Beavis, S.A. Belomestnykh, I. Ben-Zvi, D.M. Gassner, L.R. Hammons, J.P. Jamilkowski, P. K. Kankiya, R.F. Lambiase, V. Litvinenko, R.J. Michnoff, T.A. Miller, J. Morris, V. Ptitsyn, T. Seda, B. Sheehy, K.S. Smith, E. Wang, W. Xu
    BNL, Upton, Long Island, New York, USA
  • S.A. Belomestnykh, I. Ben-Zvi, L.R. Hammons, V. Litvinenko, V. Ptitsyn
    Stony Brook University, Stony Brook, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy
BNL R&D ERL beam commissioning started in June 2014 [*]. The key components of R&D ERL are the highly damped 5-cell 704 MHz superconducting RF cavity and the high-current superconducting RF gun. The gun is equipped with a multi-alkaline photocathode insertion system. The first photocurrent from ERL SRF gun has been observed in November 2014. In June 2015 a high charge 0.5nC and 20 uA average current were demonstrated. In July 2015 gun to dump beam test started. The beam was successfully transported from the SRF gun through the injection system, then through the linac to the beam dump. All ERL components have been installed. In October 2015, SRF gun cavity has been found contaminated during severe cathode stalk RF conditioning. This cavity has been sent for repair and modification for later use in low-energy RHIC electron cooler (LEReC)[**]. LEReC scheduled to start commissioning in early of 2018. We present our results of BNL ERL beam commissioning, the measured beam properties, the operational status, and future prospects.
*) D.Kayran et al., Status and commissioning results of the R&D ERL at BNL. Proc. ERL2015, p. 11-14
**)J. Kewisch et al., ERL for Low Energy Electron Cooling at RHIC (LEReC). Proc. ERL2015, p. 67-71
 
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TUOP02 CBETA: The Cornell/BNL 4-Turn ERL with FFAG Return Arcs for eRHIC Prototyping linac, electron, cryomodule, gun 384
 
  • G.H. Hoffstaetter, J. Barley, A.C. Bartnik, I.V. Bazarov, J. Dobbins, B.M. Dunham, R.G. Eichhorn, R.E. Gallagher, C.M. Gulliford, Y. Li, M. Liepe, W. Lou, C.E. Mayes, J.R. Patterson, D.M. Sabol, E.N. Smith, K.W. Smolenski
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • I. Ben-Zvi, J.S. Berg, S.J. Brooks, G.J. Mahler, F. Méot, M.G. Minty, S. Peggs, V. Ptitsyn, T. Roser, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, H. Witte
    BNL, Upton, Long Island, New York, USA
  • D. Douglas
    JLab, Newport News, Virginia, USA
 
  Cornell University has prototyped technology essential for any high brightness electron ERL. This includes a DC gun and an SRF injector Linac with world-record current and normalized brightness in a bunch train, a high-current CW cryomodule, a high-power beam stop, and several diagnostics tools for high-current and high-brightness beams, e.g. slid measurements for 6-D phase-space densities, a fast wire scanner for beam profiles, and beam loos diagnostics. All these are now available to equip a one-cryomodule ERL, and laboratory space has been cleared out and is radiation shielded to install this ERL at Cornell. BNL has designed a multi-turn ERL for eRHIC, where beam is transported more than 20 times around the RHIC tunnel. The number of transport lines is minimized by using two non-scaling (NS) FFAG arcs. A collaboration between BNL and Cornell has been formed to investigate the new NS-FFAG optics and the multi-turn eRHIC ERL design by building a 4-turn, one-cryomodule ERL at Cornell. It has a NS-FFAG return loop built with permanent magnets and is meant to accelerate 40mA beam to 200MeV.  
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TUOP07 High Performance Next-Generation Nb3Sn Cavities for Future High Efficiency SRF Linacs cavity, niobium, accelerating-gradient, pulsed-power 398
 
  • D.L. Hall, J.J. Kaufman, M. Liepe, J.T. Maniscalco, R.D. Porter
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Funding: DOE
A 1.3 GHz ILC-shape single-cell Nb3Sn cavity fabricated at Cornell has shown record performance, exceeding the cryogenic efficiency of niobium cavities at the gradients and quality factors demanded by some contemporary accelerator designs. An optimisation of the coating process has resulted in more cavities of the same design that achieve similar performance, proving the reproducibility of the method. In this paper, we discuss the current limitations on the peak accelerating gradients achieved by these cavities. In particular, high-pulsed-power RF testing, and thermometry mapping of the cavity during CW operation, are used to draw conclusions regarding the nature of the quench limitation. In light of these promising results, the feasibility and utility of applying the current state of the technology to a real-life application is discussed.
 
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TUOP08 On Magnetic Flux Trapping in Superconductors solenoid, niobium, experiment, cavity 402
 
  • R.G. Eichhorn, J. Hoke, Z. Mayle
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Magnetic flux trapped on the cool-down has become an important factor in the performance in superconducting cavities. We have conducted flux trapping experiments on samples that reveal a very interesting feature of the mechanism on flux trapping which might impact magnetic shielding concepts of future cryomodules.  
slides icon Slides TUOP08 [1.787 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUOP08  
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TUPRC015 Final Acceptance Test of SRF Photo-Injector Cold String for the BERLinPro Energy Recovery Linac cavity, cathode, gun, target 445
 
  • A. Neumann, D. Böhlick, P. Echevarria, A. Frahm, F. Göbel, T. Kamps, J. Knobloch, O. Kugeler, M. Schuster, J. Ullrich, A. Ushakov
    HZB, Berlin, Germany
  • A. Burrill
    SLAC, Menlo Park, California, USA
  • G. Ciovati, P. Kneisel
    JLab, Newport News, Virginia, USA
  • A. Matheisen, M. Schalwat, M. Schmökel
    DESY, Hamburg, Germany
  • E.N. Zaplatin
    FZJ, Jülich, Germany
 
  Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin and grants of Helmholtz Association.
Helmholtz-Zentrum Berlin (HZB) is currently designing and building an high average current all superconducting CW driven ERL as a prototype to demonstrate low normalized beam emittance of 1 mm·mrad at 100mA and short pulses of about 2 ps. In order to achieve these demanding goals HZB started a staged program for developing this class of required high current, high brightness SRF electron sources. In this contribution we will present the current status of the module assembly and testing of the prototype SRF photo-injector cavity cold string. The steps taken to install the cathode insert system with the cavity in the cleanroom and the following horizontal test of the cold string as final acceptance test prior installation into its cryostat are shown. First beam in a dedicated diagnostics teststand called Gunlab are planned for this winter.
 
poster icon Poster TUPRC015 [2.077 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPRC015  
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TUPRC024 Design and Implementation of an Automated High-Pressure Water Rinse System for FRIB SRF Cavity Processing cavity, alignment, operation, controls 468
 
  • I.M. Malloch, E.S. Metzgar, L. Popielarski, S. Stanley
    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.
Traditionally, high-pressure water rinse (HPR) systems have consisted of relatively simple pump and rinse wand actuator systems intended to clean superconducting radio frequency (SRF) cavities during processing prior to test assembly. While these types of systems have proven effective at achieving satisfactory levels of cleanliness, large amounts of operator touch-labor are involved, especially in SRF cavities with complex geometries, where several fixture changes and cavity manipulations may be required. With this labor comes the risk of cavity damage or contamination, and the expense of the operator's time. To reduce this operator intervention and maximize cavity cleanliness and process throughput, a new, fully-automated, robotic HPR system has been commissioned in the Facility for Rare Isotope Beams (FRIB) cavity processing facility. This paper summarizes the design and commissioning process of the HPR system, and demonstrates improvements to the FRIB processing facility through the minimization of cavity contamination risk and reduction of technician labor through system automation. Comparative cavity RF test results are presented to further demonstrate system effectiveness.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPRC024  
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TUPRC025 Low Temperature Nitrogen Baking of a Q0 SRF Cavities cavity, niobium, radio-frequency, impedance 472
 
  • P.N. Koufalis, F. Furuta, M. Ge, D. Gonnella, J.J. Kaufman, M. Liepe, J.T. Maniscalco, R.D. Porter
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  Nitrogen-doping has led to an unprecedented increase in the intrinsic quality factor of bulk-niobium superconducting RF cavities. So far, high temperature baking in a nitrogen atmosphere is used almost exclusively to dope cavities. Recently, we have set focus on low temperature baking to produce similar performance increases and we present those results here.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPRC025  
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TUPLR007 LCLS-II Cryomodules Production at Fermilab cryomodule, cavity, vacuum, alignment 481
 
  • T.T. Arkan, C.J. Grimm, J.A. Kaluzny, Y.O. Orlov, T.J. Peterson, K. Premo
    Fermilab, Batavia, Illinois, USA
 
  Funding: US DOE
LCLS-II is an 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 (JLab) will assemble 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. Fermilab and JLab will each assemble and test a prototype 1.3 GHz cryomodule to assess the results of the CW modifications, in advance of 16 and 17 production 1.3 GHz cryomodules, respectively. Fermilab is solely responsible for the 3.9 GHz cryomodules. After the prototype cryomodule tests are complete and lessons learned incorporated, both laboratories will increase their cryomodule production rates to meet the challenging LCLS-II project requirement of approximately one cryomodule per month per laboratory. This paper presents the Fermilab Cryomodule Assembly Facility (CAF) infrastructure for LCLS-II cryomodule production, the Fermilab prototype 1.3 GHz CW cryomodule (pCM) assembly and readiness for production assembly.
 
poster icon Poster TUPLR007 [2.474 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR007  
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TUPLR011 Performance of the Novel Cornell ERL Main Linac Prototype Cryomodule cavity, linac, cryomodule, HOM 492
 
  • F. Furuta, J. Dobbins, R.G. Eichhorn, M. Ge, D. Gonnella, G.H. Hoffstaetter, M. Liepe, T.I. O'Connell, P. Quigley, D.M. Sabol, J. Sears, E.N. Smith, V. Veshcherevich
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
 
  The main linac cryomodule (MLC) for the future energy-recovery linac (ERL) based X-ray light source at Cornell has been designed, fabricated, and tested. It houses six 7-cell SRF cavities with individual higher order-modes (HOMs) absorbers, cavity frequency tuners, and one magnet/BPM section. Cavities have achieved the specification values of 16.2MV/m with high-Q of 2.0·1010 in 1.8K in continuous wave (CW) mode. During initial MLC cavity testing, we encountered some field emission, reducing Q and lowering quench field. To overcome field emission and find optimal cool-down parameters, RF processing and thermal cycles with different cool-down conditions has been done. Here we report on these studies and present final results from the MLC cavity performance.  
poster icon Poster TUPLR011 [2.389 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR011  
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TUPLR022 Particulate Study on Materials for Cleanroom Assembly of SRF Cavities cavity, niobium, operation, experiment 512
 
  • L. Zhao, A.V. Reilly
    JLab, Newport News, Virginia, USA
 
  Reducing particulates is an important aspect for clean-room operation. Knowing that it is impossible to completely eliminate all particulates in a clean room, efforts have been made to prevent particulates from entering SRF cavities during high pressure rinsing (HPR) and assembly. At Jefferson Lab, one practice to achieve this goal has been clamping covers to cavity open flanges during assembly. Several cover materials that have been used are examined and alternative candidate materials are under development. Clamps as a known particulate generator are carefully examined and cleaning efficiency of different methods is studied. Cover tests were done on different cavity flanges, including an LCLS-II beam pipe flange, which helps the selection of cover materials for prototype and production of the project.
Authored by Jefferson Science Associates, LLC under U.S. DOE Contracts DE-AC05-06OR23177 and DE-AC02-76SF00515 for the LCLS-II Project.
 
poster icon Poster TUPLR022 [1.282 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR022  
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TUPLR023 Impurity Content Optimization to Maximize Q-Factors of Superconducting Resonators cavity, factory, niobium, superconductivity 515
 
  • M. Martinello, M. Checchin, A. Grassellino, O.S. Melnychuk, S. Posen, A. Romanenko, D.A. Sergatskov
    Fermilab, Batavia, Illinois, USA
  • M. Checchin
    Illinois Institute of Technology, Chicago, Illlinois, USA
  • J. Zasadzinski
    IIT, Chicago, Illinois, USA
 
  Quality factor of superconducting radio-frequency (SRF) cavities is degraded whenever magnetic flux is trapped in the cavity walls during the cooldown. In this contribution we study how the trapped flux sensitivity, defined as the trapped flux surface resistance normalized for the amount of trapped flux, depends on the mean free path. A systematic study of a variety of 1.3 GHz cavities with different surface treatments (EP, 120 C bake and different N-doping) is carried out. A bell shaped trend appears for the range of mean free path studied. Over-doped cavities fall at the maximum of this curve defining the largest values of sensitivity. In addition, we have studied the trend of the BCS surface resistance contribution as a function of mean free path, showing that N-doped cavities follow close to the theoretical minimum. Adding these results together we show that the 2/6 N-doping treatment gives the highest Q-factor values at 2 K and 16 MV/m, as long as the magnetic field fully trapped during the cavity cooldown is lower than 10 mG.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR023  
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TUPLR025 Optimal Nitrogen Doping Level to Reach High Q0 cavity, cryomodule, niobium, electron 523
 
  • D. Gonnella, 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
 
  Funding: NSF and US DOE
New continuous wave (CW) accelerators such as LCLS-II at SLAC require many SRF cavities operating in the medium field region at unprecedented high Q. In order to achieve this demanding goal, nitrogen-doping of the SRF cavities will be used. Nitrogen-doping has been shown to affect the BCS resistance both by a lowering of Rbcs at low fields and by the introduction of an anti-Q slope which enables the Q to continue increasing as the RF field is increased. The exact strength of this anti-Q slope is heavily dependent on the doping recipe and specifically the mean free path of the RF penetration layer of the doped cavities. In addition to its effect on Rbcs, the mean free path affects the amount of residual resistance obtained due to trapped magnetic flux. We have analyzed nine cavities prepared with different levels of nitrogen-doping to understand how BCS and residual resistance are affected by changes in the mean free path. Here we present a model based on these experimental results to predict the optimal doping level to reach the maximum Q at 16 MV/m based on the ambient magnetic field conditions. We find that if the cavities can be cooled with small amounts of trapped flux, moderate nitrogen-doping is better, while if they will have large amounts of trapped flux, lighter dopings should be used.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR025  
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TUPLR030 First FRIB β=0.53 Prototype Coldmasss Build cavity, cryomodule, vacuum, solenoid 538
 
  • D.R. Victory, K. Elliott, B. Oja, J.T. Popielarski, M.S. Wilbur
    FRIB, East Lansing, 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.
The β=0.53 coldmass consists of eight Superconducting Radio Frequency (SRF) β=0.53 cavities, eight Fundamental mode Power Couplers (FPC), and one 8 T solenoid. This is the first coldmass with this version of cavity and it has brought new challenges to overcome. The Facility for Rare Isotope Beams (FRIB) contains 18 cryomodules with β=0.53 cavity coldmasses, and this type of coldmass is the highest power and most produced ones in FRIB. During the final cleaning stage and the cavity assembly, particle detection equipment is used to verify the cavity cleanliness levels for cavity certification test and for coldmass assembly. This method allows for cleanliness detection of specific areas inside the cavity at any time a vacuum flange is off. The fixtures, techniques and procedures used to build the β=0.53 coldmasses will be presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR030  
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TUPLR033 First FRIB β=0.041 Production Coldmass Build cavity, solenoid, alignment, cryomodule 541
 
  • K. Elliott, S.J. Miller, B. Oja, J.T. Popielarski, L. Popielarski, D.R. Victory, M.S. Wilbur, T. Xu
    FRIB, East Lansing, USA
  • M. Wiseman
    JLab, Newport News, Virginia, 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.
Three β=0.041 cryomodules are required for the Facility for Rare Isotope Beams (FRIB) accelerator. Cleanroom assembly of all three coldmasses for these cryomodules has been completed. The cleanroom assembly includes; the superconducting radio frequency (SRF) cavities, the superconducting solenoids, fundamental power couplers (FPC), beam position monitors, alignment rail, and transport cart. This paper will provide an overview of the techniques and procedures used to assemble this cavity string such that it can be used in the FRIB accelerator.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR033  
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TUPLR035 RF Analysis of Electropolishing for EXFEL Cavities Production at Ettore Zanon Spa cavity, shielding, cathode, superconductivity 544
 
  • A.A. Sulimov
    DESY, Hamburg, Germany
  • M. Giaretta, A. Gresele, A. Visentin
    Ettore Zanon S.p.A., Nuclear Division, Schio, Italy
 
  After successful finishing of superconducting cavities mass production at Ettore Zanon S.p.A. (EZ) for the European XFEL (EXFEL), the authors had the possibility to provide a detailed analysis of the electropolishing (EP) process. The analysis of EP material removal is based on specified RF measurements and was used for the determination of both, the ratio between cavity's iris and equator and uniformity in different cells. A comparison of the RF measurements results with mechanical measurements is presented.  
poster icon Poster TUPLR035 [0.195 MB]  
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TUPLR041 Manufacturing, Assembly and Tests of the LIPAc Medium Energy Beam Transport Line (MEBT) vacuum, linac, controls, beam-transport 554
 
  • I. Podadera, P. Abramian, B. Brañas, J. Calero, J. Castellanos, J.M. García, D. Gavela, A. Guirao, J.L. Gutiérrez, D. Jiménez-Rey, M. Lafoz, D. López, L.M. Martínez, E. Molina Marinas, J. Mollá, C. Oliver, A. Soleto, F. Toral, R. Varela, V. Villamayor
    CIEMAT, Madrid, Spain
  • J. Castellanos
    UNED, Madrid, Spain
  • O. Nomen
    IREC, Sant Adria del Besos, Spain
 
  Funding: This work has been funded by the Spanish Ministry of Economy and Competitiveness under the Agreement as published in BOE, 16/01/2013, page 1988 and the project FIS2013-40860-R.
LIPAc* will be a 9 MeV, 125 mA CW deuteron accelerator which aims to validate the technology that will be used in the future IFMIF-DONES accelerator**. The acceleration of the beam will be carried out in two stages. An RFQ will increase the energy up to 5 MeV before a Superconducting RF (SRF) linac made of a chain of eight Half Wave Resonators bring the particles to the final energy. Between both stages, a Medium Energy Beam Transport line (MEBT)*** is in charge of transporting and matching the beam between the RFQ and the SRF. The transverse focusing of the beam is controlled by five quadrupole magnets with integrated steerers, grouped in one triplet and one doublet. Two buncher cavities surrounding the doublet handle the longitudinal dynamics. Two movable collimators are also included to purify the beam optics coming out the RFQ and avoid losses in the SRF. In this contribution, the final integrated design of the beamline will be shown, together with the auxiliaries. The manufacturing of all the components and the integration in the beamline will be depicted. The final tests carried out to the beamline prior to the installation in the accelerator will be also reported.
* P. Cara et al., IPAC16, to be published, Busan, Korea (2016).
** A. Ibarra et al., Fus. Sci. Tech., 66, 1, p. 252-259 (2014).
*** I. Podadera et al., IPAC11, San Sebastian, Spain (2011).
 
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TUPLR048 Status and Lesson Learned from Manufacturing of FPC Couplers for the XFEL Program Windows, cryomodule, factory, status 572
 
  • S. Sierra, G. Garcin, Ch.L. Lievin, G. Vignette
    TED, Velizy-Villacoublay, France
  • A. Gallas, W. Kaabi
    LAL, Orsay, France
  • M. Knaak, M. Pekeler, L. Zweibaeumer
    RI Research Instruments GmbH, Bergisch Gladbach, Germany
 
  For the XFEL accelerator, Thales, RI research Instrument and LAL are working on the manufacturing, assembly and conditioning of Fundamental power couplers. 670 couplers has been manufactured. The main characteristics of these couplers are remained at 1.3 GHz. The paper describes the full production activity from the starting of the program We describe the lesson learned from a mass production of FPC coupler and different steps necessaries for obtaining a rate up to 10 couplers a week. we propose also some other way to be optimized for a future possible mass production of such components. With comparison of processes and adaptation which could benefit to an increase rate, if needed, including some of them which could be studies from the coupler definition to the manufacturing process in order to obtain a stable and possible increased rate or lower cost of production by decreasing the risks on programs. The status of the production curve during the program is also given  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR048  
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TUPLR061 Cryomodule and Power Coupler for RIKEN Superconducting QWR cryomodule, cavity, vacuum, linac 598
 
  • K. Ozeki, O. Kamigaito, H. Okuno, N. Sakamoto, K. Suda, Y. Watanabe, K. Yamada
    RIKEN Nishina Center, Wako, Japan
  • E. Kako, H. Nakai, K. Umemori
    KEK, Ibaraki, Japan
  • K. Okihira
    MHI, Hiroshima, Japan
  • K. Sennyu, T. Yanagisawa
    MHI-MS, Kobe, Japan
 
  In RIKEN Nishina Center, we are constructing a prototype of low-beta superconducting QWR for ions. Presently, the designs of cryomodule, which contains two QWRs, and power coupler are being carried out. In this contribution, the progress situation for the construction of cryomodule and power coupler will be reported. This work was funded by ImPACT Program of Council for Science, Technology and innovation (Cabinet Office, Government of Japan).  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR061  
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TUPLR072 Fabrication and Low Temperature Test Plan for Rare Isotope Science Project cryomodule, cavity, radiation, linac 619
 
  • W.K. Kim, M.J. Joung, Y. Jung, H. Kim, J.-W. Kim, Y. Kim, I. Shin
    IBS, Daejeon, Republic of Korea
 
  Quarter-wave resonator (QWR), half-wave resonator (HWR) and single-spoke resonator (SSR) cryomodules are used for RAON accelerator. The layout of RAON accelerator and three types of cryomodules such as QWR, HWR and SSR are shown in the linac. SRF test facility which consists of cryoplant, cleanroom, vertical test facility and horizontal test facility is constructed. Cleanroom has high pressure rinsing (HPR), ultrasonic cleaning (USC), buffered chemical polishing (BCP), high vacuum furnace and cavity assemble place. The test plan for cavity and cryomodules is presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR072  
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TUP106004 Status of RRR Analysis for RAON Accelerator niobium, cavity, vacuum, superconductivity 628
 
  • Y. Jung, H. Kim, W.K. Kim
    IBS, Daejeon, Republic of Korea
  • J. Lee, J. Seo
    Vitzrotech Co., Ltd., Ansan City, Kyunggi-Do, Republic of Korea
 
  Residual resistance ratio (RRR) of 300-grade niobium has been analyzed to find optimal welding condition for a superconducting cavity. RRR values were not only measured along the welding directions, but also perpendicular to the welding lines. In this presentation, we will show the RRR analysis as a function of the distance, the welding speed, and the welding pressure.  
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TUP106006 Vertical Test Results on ESS Medium Beta Elliptical Cavity Prototype cavity, linac, cryomodule, status 631
 
  • E. Cenni
    CEA/IRFU, Gif-sur-Yvette, France
  • S. Berry, P. Bosland, F. Éozénou, L. Maurice, J. Plouin, C. Servouin
    CEA/DSM/IRFU, France
  • G. Costanza
    Lund University, Lund, Sweden
  • C. Darve
    ESS, Lund, Sweden
  • G. Devanz, X. Hanus, F. Peauger, D. Roudier
    CEA/DRF/IRFU, Gif-sur-Yvette, France
 
  The ESS elliptical superconducting Linac consists of two types of 704.42 MHz cavities, medium and high beta, to accelerate the beam from 216 MeV (spoke cavity Linac) up to the final energy at 2 GeV. The last Linac optimization, called Optimus+ [1], has been carried out taking into account the limitations of SRF cavity performance (field emission). The medium and high-beta parts of the Linac are composed of 36 and 84 elliptical cavities, with geometrical beta values of 0.67 and 0.86 respectively. This work presents the latest vertical test results on ESS medium beta elliptical cavity prototypes. We describe the cavity preparation procedure from buffer chemical polishing to vertical test. Finally magnetic probes (Fluxgate) were installed on the cavity to determine magnetic field background during vertical test. The latest vertical test results showed that our cavity design performance are beyond requirements.  
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WE1A01 PIP-II Injector Test: Challenges and Status rfq, cryomodule, operation, solenoid 641
 
  • P. Derwent, J.-P. Carneiro, J.P. Edelen, V.A. Lebedev, L.R. Prost, A. Saini, A.V. Shemyakin, J. Steimel
    Fermilab, Batavia, Illinois, USA
 
  The Proton Improvement Plan II (PIP-II) at Fermilab is a program of upgrades to the injection complex. At its core is the design and construction of a CW-compatible, pulsed H superconducting RF linac. To validate the concept of the front-end of such machine, a test accelerator known as PXIE is under construction. It includes a 10 mA DC, 30 keV H ion source, a 2 m-long Low Energy Beam Transport (LEBT), a 2.1 MeV CW RFQ, followed by a Medium Energy Beam Transport (MEBT) that feeds the first of 2 cryomodules increasing the beam energy to about 25 MeV, and a High Energy Beam Transport section (HEBT) that takes the beam to a dump. The ion source, LEBT, RFQ, and initial version of the MEBT have been built, installed, and commissioned. This report presents the overall status of the PXIE warm front end, including results of the beam commissioning through the installed components, and progress with SRF cryomodules and other systems.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-WE1A01  
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WE1A03 The Superconducting Radio-Frequency Linear Accelerator Components for the European Spallation Source: First Test Results cavity, cryomodule, linac, proton 651
 
  • C. Darve, N. Elias, F. Schlander
    ESS, Lund, Sweden
  • C. Arcambal, P. Bosland, E. Cenni, G. Devanz
    CEA/IRFU, Gif-sur-Yvette, France
  • S. Bousson, P. Duthil, G. Olivier, G. Olry, D. Reynet
    IPN, Orsay, France
  • G. Costanza
    Lund University, Lund, Sweden
  • H. Li, R.J.M.Y. Ruber, R. Santiago Kern
    Uppsala University, Uppsala, Sweden
  • F. Peauger
    CEA/DSM/IRFU, France
 
  The European Spallation Source requires a pulsed Linac with an average beam power on the target of 5MW which is about five times higher than the most powerful spallation source in operation today. Over 97% of the acceleration occurs in superconducting cavities. ESS will be the first accelerator to employ double spoke cavities to accelerate beam. Accelerating gradients of 9MV/meter is required in the spoke section. The spoke section will be followed by 36 elliptical 704 MHz cavities with a geometrical beta of 0.67 and elliptical 704 MHz cavities with a geometrical beta of 0.86. Accelerating gradients of 20MV/m is required in the elliptical section. Initial gradient test results will be presented in which results exceed expected requirements.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-WE1A03  
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WE1A04 Performance Analysis of the European XFEL SRF Cavities, From Vertical Test to Operation in Modules cryomodule, cavity, linac, controls 657
 
  • N. Walker, D. Reschke, J. Schaffran, L. Steder, M. Wenskat
    DESY, Hamburg, Germany
  • L. Monaco
    INFN/LASA, Segrate (MI), Italy
 
  More than 800 resonators have been fabricated, vertically qualified and operated in module tests before the accelerating module installation in the linac, which will be completed before the conference. An analysis of this experience, with correlation of the final cavity performances with production, preparation and assembly stages, is underway and at the time of the conference a summary of the activities will be available.  
slides icon Slides WE1A04 [3.436 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-WE1A04  
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WE2A02 FRIB Cryomodule Design and Production cryomodule, linac, cavity, alignment 673
 
  • T. Xu, H. Ao, B. Bird, N.K. Bultman, E.E. Burkhardt, F. Casagrande, C. Compton, J.L. Crisp, K.D. Davidson, K. Elliott, A. Facco, V. Ganni, A. Ganshyn, W. Hartung, M. Ikegami, P. Knudsen, S.M. Lidia, I.M. Malloch, S.J. Miller, D.G. Morris, P.N. Ostroumov, J.T. Popielarski, L. Popielarski, M.A. Reaume, K. Saito, S. Shanab, G. Shen, M. Shuptar, S. Stark, J. Wei, J.D. Wenstrom, M. Xu, Y. Xu, Y. Yamazaki, Z. Zheng
    FRIB, East Lansing, Michigan, USA
  • A. Facco
    INFN/LNL, Legnaro (PD), Italy
  • K. Hosoyama
    KEK, Ibaraki, Japan
  • M.P. Kelly
    ANL, Argonne, Illinois, USA
  • R.E. Laxdal
    TRIUMF, Vancouver, Canada
  • M. Wiseman
    JLab, Newport News, Virginia, USA
 
  Funding: U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661
The Facility for Rare Isotope Beams (FRIB), under con-struction at Michigan State University, will utilize a driver linac to accelerate stable ion beams from protons to ura-nium up to energies of >200 MeV per nucleon with a beam power of up to 400 kW. Superconducting technology is widely used in the FRIB project, including the ion sources, linac, and experiment facilities. The FRIB linac consists of 48 cryomodules containing a total of 332 superconducting radio-frequency (SRF) resonators and 69 superconducting solenoids. We report on the design and the construction of FRIB cryomodules.
 
slides icon Slides WE2A02 [3.823 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-WE2A02  
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THOP01 Experimental Study of Nucleation for Nb3Sn Diffusion Coatings on Niobium SRF Cavities niobium, experiment, background, accelerating-gradient 740
 
  • U. Pudasaini, M.J. Kelley
    The College of William and Mary, Williamsburg, Virginia, USA
  • G.V. Eremeev, M.J. Kelley, C.E. Reece
    JLab, Newport News, Virginia, USA
 
  Funding: Partially authored by Jefferson Science Associates under Contract No. DE-AC05-06OR23177. Work at William & Mary supported by Office of High Energy Physics under grant SC0014475
Nb3Sn has the potential to achieve superior performance both in terms of operating temperature (4.2 K vs 2 K) and accelerating gradient resulting in significant reduction in both initial and operating costs of SRF linacs. Cavity interior surface coatings are obtained by two-step vapor diffusion: nucleation followed by deposition. To gain more understanding of nucleation and its effect on the subsequent coating, we investigated the effect of varying parameters in a typical tin/tin chloride process. We report findings obtained by SEM/EDS, AFM, SAM and other materials characterization approaches.
 
slides icon Slides THOP01 [2.784 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THOP01  
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THOP02 Investigation of Nitrogen Absorption Rate and Nitride Growth on SRF Cavity Grade RRR Niobium as a Function of Furnace Temperature niobium, cavity, ion, injection 744
 
  • A.D. Palczewski, C.E. Reece
    JLab, Newport News, Virginia, USA
  • M.J. Kelley
    The College of William and Mary, Williamsburg, Virginia, USA
  • J. Tuggle
    Virginia Polytechnic Institute and State University, Blacksburg, USA
 
  Funding: Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
The current state of the art processing of niobium superconducting radio frequency cavities with nitrogen diffusion is performed at 800C in a furnace with a partial pressure of approximately ~20 mtorr of nitrogen. Multiple studies have shown the bulk of the nitrogen absorbed by the niobium forms a thick (1-3 microns) non-superconducting nitride layer which must be removed to produce optimal RF results. The depth profiling of interstitial nitrogen and surface nitrides has already been probed using SIMS measurements. These measurements have also been modeled by extrapolating data from nitride growth studies performed at atmospheric pressure and temperatures above 1000 C (**). One open question is whether there is a diffusion zone at lower temperature in which the niobium will absorb nitrogen but not create a non-superconducting nitride layer; or is the absorption of nitrogen only possible by first forming a nitride buffer layer which then frees up nitrogen for absorption. A systematic study of absorption rate vs. temperature and correlated SIMS measurements needs to be performed to answer this question. We report on the absorption rate vs. temperature from 400 C to 900 C of cavity grade niobium with metallurgically flat witness samples. The witness samples surface depth profile of NbN via SIMS's will be presented and correlated to the absorption.**
* Gonnella et al., Proceedings of SRF2015 Pre-release MOPB042 (2015)
** Tuggle et al., Investigation of Low-Level Nitrogen in Niobium by Secondary Ion Mass Spectrometry, these proceedings (2016)
 
poster icon Poster THOP02 [2.235 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THOP02  
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THOP03 Cold Bead-Pull Test Stand for SRF Cavities cavity, HOM, niobium, simulation 748
 
  • A.V. Vélez, A. Frahm, J. Knobloch, A. Neumann
    HZB, Berlin, Germany
 
  Bead-pull measurements represent a final step in the fabrication process of an SRF cavity. These tests allow to characterize the flatness of the field profile in order to perform mechanical tuning if needed. These test has been always performed at room temperature, where material properties differ from the superconducting state properties. Still questions like mechanical deformation due to assymetrical thermal shrincage have not yet been answered experimentaly. In this paper, an upgrade of the former Cold-Bead pull system developed by HZB [1] is presented. This test stand is capable of holding a 9-cell Tesla cavity at LHe temperature providing a realistic insight to cavity parameters under realistic conditions. A copper test pill-box is placed in series with the multi-cell cavity in order to perform 1.8K calibration of the bead. Results will be presented on this paper and compared to electromagnetic simulations.  
slides icon Slides THOP03 [2.731 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THOP03  
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THPRC008 Status of the Development and Manufacturing of LCLS-II Fundamental Power Couplers status, Windows, cryomodule, factory 782
 
  • S. Sierra, G. Garcin, Ch.L. Lievin, C. Ribaud, G. Vignette
    TED, Velizy-Villacoublay, France
  • M. Knaak, A. Navitski, M. Pekeler, L. Zweibaeumer
    RI Research Instruments GmbH, Bergisch Gladbach, Germany
 
  For the LCLS-II project, Thales and RI research Instrument are working on the manufacturing and assembly of the Fundamental Power Couplers. The paper describes the production of the Fundamental Power Couplers for the LCLS-II project. The main characteristics of these couplers are remained at 1.3 GHz. It describes the main challenges to be overcome principally on the Warm Internal conductor, with a thickness of copper of 150μm. The results obtained on this coating We describe the results obtained on the prototype phase and the status of the serial production on the date of the paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPRC008  
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THPRC017 Performance of SRF Cavity Tuners at LCLS II Prototype Cryomodule at FNAL cavity, cryomodule, operation 808
 
  • J.P. Holzbauer, Y.M. Pischalnikov, W. Schappert, J.C. Yun
    Fermilab, Batavia, Illinois, USA
 
  Performances of the fast/slow tuners mounted on the 8 SRF cavities of first LCLS-II prototype cryomodule assembled at FNAL will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPRC017  
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THPRC021 Status of β=0.53 Pre-Production Cryomodule cavity, linac, cryomodule, alignment 811
 
  • H. Ao, B. Bird, G.D. Bryant, B. Bullock, N.K. Bultman, C. Compton, A. Facco, J.D. Hulbert, S.J. Miller, J.T. Popielarski, L. Popielarski, M.A. Reaume, K. Saito, M. Shuptar, J. Simon, S. Stark, B.P. Tousignant, J.D. Wenstrom, K. Witgen, T. Xu, Z. Zheng
    FRIB, East Lansing, 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 driver linac for the Facility for Rare Isotope Beams (FRIB) comprises four kinds of cavities (=0.041, 0.085, 0.29, and 0.53) and six types of cryomodules including matching modules. FRIB has started the fabrication of a β=0.53 preproduction cryomodule, which is the first prototype for a half-wave (=0.29 and 0.53) cavity. This paper describes the fabrication progress and the lessons learned from the β=0.53 preproduction cryomodule.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPRC021  
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THPRC026 Optical Design of the PI-Test MEBT Beam Scraping System focusing, linac, emittance, space-charge 827
 
  • A. Saini, A.V. Shemyakin
    Fermilab, Batavia, Illinois, USA
 
  PI-Test [1] is an accelerator facility under construction at Fermilab that will provide a platform to demonstrate critical technologies and concept of front-end of the PIP-II superconducting radio frequency (SRF) linac. It will be capable to accelerate an H ion beam with average current of 2 mA up to 25 MeV in continuous wave (CW) regime. To protect the SRF components from beam irradiation, the Medium Energy Beam Transport (MEBT) section of PI-Test includes an elaborated beam scraping system. It consists of four assemblies spread along the MEBT, with each assembly composed of four radiation-cooled, electrically isolated plates that can be moved into the beam in horizontal and vertical direction. The primary objectives of scraping system are to intercept particles with large transverse action and to protect the beamline elements and SRF linac in case of errors with beam focusing or steering. In this paper we formulate requirements for the scraping system and discuss factors affecting its efficiency. An optical design compatible with PI-Test MEBT is also presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPRC026  
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THPLR008 3-Cell Superconducting Traveling Wave Cavity Tuning at Room Temperature cavity, accelerating-gradient, feedback, factory 858
 
  • R.A. Kostin
    LETI, Saint-Petersburg, Russia
  • P.V. Avrakhov, A. Kanareykin
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • T.N. Khabiboulline, A.M. Rowe, N. Solyak, V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
 
  Funding: Work supported by US DOE SBIR # DE-SC0006300
A superconducting traveling wave (SCTW) cavity with a feedback waveguide will support a higher average acceleration gradient compared to conventional SRF standing wave cavities [1]. Euclid Techlabs, in collaboration with Fermilab, previously demonstrated a high accelerating gradient in a single cell cavity with a feedback waveguide [2], and the new waveguide design did not limit the cavity performance. The next step is high gradient traveling wave SRF cavity test. A 3-Cell SCTW cavity was designed and developed [3] to demonstrate the SRF traveling wave regime. Two Nb SCTW cavities were built, characterized and cold tested in 2016. This paper presents the results of cavity inspection, field flatness analysis, along with a discussion of the tuning procedure.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR008  
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THPLR027 Progress Towards a 2.0 K Half-Wave Resonator Cryomodule for Fermilab's PIP-II Project cryomodule, vacuum, cavity, linac 906
 
  • Z.A. Conway, A. Barcikowski, G.L. Cherry, R.L. Fischer, B.M. Guilfoyle, C.S. Hopper, M. Kedzie, M.P. Kelly, S.H. Kim, S.W.T. MacDonald, P.N. Ostroumov, T. Reid
    ANL, Argonne, Illinois, USA
  • V.A. Lebedev, A. Lunin
    Fermilab, Batavia, Illinois, USA
 
  Funding: This material is supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics and Office of High-Energy Physics, Contracts No. DE-AC02-76-CH03000 and DE-AC02-06CH11357.
In support of Fermilab's Proton Improvement Plan-II project Argonne National Laboratory is constructing a superconducting half-wave resonator cryomodule. This cryomodule is designed to operate at 2.0 K, a first for low-velocity ion accelerators, and will accelerate ≥1 mA proton/H beams from 2.1 to 10.3 MeV. Since 2014 the construction of 9 162.5 MHz b = 0.112 superconducting half-wave resonators, the vacuum vessel and the majority of the cryomodule subsystems have been finished. Here we will update on the status of this work and report on preliminary cavity test results. This will include cavity performance measurements where we found residual resistances of < 3 nanoOhms at low fields and peak voltage gains of 5.9 MV, which corresponds to peak surface fields of 134 MV/m and 144 mT electric and magnetic respectively.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR027  
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THPLR028 Simulation of Mechanical Oscillations in PIP-II Cryomodule Using ACE3P cavity, simulation, linac, proton 910
 
  • L. Xiao, O. Kononenko, C.-K. Ng
    SLAC, Menlo Park, California, USA
 
  Funding: Work supported by the US DOE under contract DE-AC02-76SF00515.
The linac in the PIP-II project at Fermilab consists of different sections of superconducting rf (SRF) cavities that can accelerate the proton beams to 800 MeV. At the end of the linac is a section containing a number of HB (β = 0.92) cryomodules operating at 650 MHz, with each cryomodule consisting of six SRF cavities. Previous calculations have been carried out to determine the mechanical modes of a single cavity in the 650 MHz cryomodule. In this paper, the parallel code suite ACE3P is used to evaluate the mechanical modes for a string of SRF cavities in the 650 MHz cryomodule. The effects of multi cavities on the mechanical mode frequencies and any possible coupling between cavities will be investigated.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR028  
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THPLR029 Update on the SC 325 MHz CH-Cavity and Power Coupler Processing cavity, linac, ion, heavy-ion 913
 
  • M. Busch, M. Amberg, M. Basten, F.D. Dziuba, P.A. Mundine, H. Podlech, U. Ratzinger
    IAP, Frankfurt am Main, Germany
 
  Funding: Work supported by GSI, BMBF Contr. No. 05P15RFRBA
The 325 MHz CH-Cavity which has been developed and successfully vertically tested at the Institute for Applied Physics, Frankfurt, has reached the final production stage. The helium vessel has been welded to the frontal joints of the cavity and further tests in a horizontal environment are in preparation. Furthermore the corresponding power couplers have been conditioned and tested at a dedicated test stand up to the power level of 40 kW (pulsed) for the targeted beam operation. The final step of the whole prototype development is a beam test with a 11.4 AMeV, 10 mA ion beam at GSI, Darmstadt.
 
poster icon Poster THPLR029 [1.858 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR029  
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THPLR035 FZJ SRF TSR with Integrated LHe Vessel cavity, simulation, operation, electromagnetic-fields 926
 
  • E.N. Zaplatin
    FZJ, Jülich, Germany
 
  Single- or Multi-Spoke SRF cavities are one of the basic accelerating structures for the low and intermediate energy part of many accelerators. Different types of external loads on the resonator walls predetermine the main working conditions of the SC cavities. The most important of them are very high electromagnetic fields that result in strong Lorentz forces acting on cavity walls and the pressure on cavity walls from the helium tank that also deforms the cavity shape. For the accelerators operating in pulsed regime the Lorentz forces are the dominant factor. The liquid helium vessel pressure instability even for 2K operations is the source of large microphonics and dominates for cw operation. Here we propose an innovative integrated helium vessel-cavity and stiffener design that will provide an effective passive damping minimizing df/dp ratio. Minimizing df/dp may be accomplished without an enhancement of the structure rigidity, which in turn minimizes the load on the cavity tuner. A separate stiffening scheme reducing Lorentz force cavity detuning to be added without violation of df/dp optimization. The developed at the Research Center in Jülich, Germany (FZJ) the 352 MHz, β=v/c=0.48 Triple-Spoke Resonator was used as an example to demonstrate the proposed conceptual integrated helium vessel-cavity design.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR035  
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THPLR036 SRF Low-Beta Elliptical Resonator Two-Ring Stiffening cavity, simulation, resonance, vacuum 929
 
  • E.N. Zaplatin
    FZJ, Jülich, Germany
  • I.V. Gonin, T.N. Khabiboulline, V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
 
  Elliptical SRF cavities are the basic accelerating structures for the high energy part of many accelerators. Since a series of external loads on the resonator walls predetermine the main working conditions of the SC cavities the detailed investigation of their mechanical properties should be conducted in parallel with the main RF design. The effects of very high electromagnetic fields that result in strong Lorentz forces and the pressure on cavity walls from the helium tank that also deforms the cavity shape, the tuning scheme resulting in the change of accelerating field profile and mechanical eigen resonances of cavities which are the main source of the microphonics must be taken into account during integrated design of the resonator and its liquid helium vessel. SRF elliptical cavities for the medium energies (β=v/c is around 0.6) inherently have more flexible shape and their ultimate stiffening with a "standard" stiffening rings installed between resonator cells becomes problematic. The second row of the rings should enhance the overall cavity rigidity. In the paper we report the basic investigations of the cavity two-row ring stiffening using FNAL 650 MHz β=0.61 as an example. The single-cell investigation results were used as the reference to develop the ultimate scheme of the helium vessel structure to ensure the best resonator stability.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR036  
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THPLR037 Development of a Superconducting Twin Axis Cavity cavity, HOM, niobium, linac 932
 
  • H. Park, A. Hutton, F. Marhauser
    JLab, Newport News, Virginia, USA
  • S.U. De Silva, J.R. Delayen, H. Park
    ODU, Norfolk, Virginia, USA
 
  Superconducting cavities with two separate accelerating axes have been proposed in the past for energy recovery linac applications. While the study showed the advantages of such cavity, the designs present serious fabrication challenges. Hence the proposed cavities have never been built. The new design, elliptical twin cavity, proposed by Jefferson Lab and optimized by Center for Accelerator Science at Old Dominion University, allows similar level of engineering and fabrication techniques of a typical elliptical cavity. This paper describes preliminary LOM and HOM spectrum, engineering and fabrication processes of the twin axis cavity.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR037  
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THPLR038 Resonance Control for Narrow Bandwidth PIP-II Cavities cavity, resonance, flattop, FPGA 936
 
  • W. Schappert, J.P. Holzbauer, Y.M. Pischalnikov
    Fermilab, Batavia, Illinois, USA
 
  The PIP-II project at FNAL calls for a SRF pulsed proton driver linac to support the expanding neutrino physics program including DUNE/LBNF. The relatively low beam current and high quality factors called for in the design means that these cavities will be operated with small RF bandwidths, meaning that they will be sensitive to microphonics. Combined with a 20 Hz pulsed operational structure and the use of four different, complex cavity geometries means that resonance control will be extremely challenging. Work is ongoing at FNAL to develop active resonance stabilization techniques using fast piezoelectric tuners in support of PIP-II. These techniques as well as testing and development results using a prototype, dressed low-beta single-spoke cavity will be presented along with an outlook for future efforts.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR038  
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