SRF2019 - List of Keywords (linac)

Paper	Title	Other Keywords	Page
MOFAA1	LCLS-II: Status, Issues and Plans	cavity, SRF, cryomodule, FEL	1
	M.C. Ross SLAC, Menlo Park, California, USA
	Funding: Work supported by Department of Energy contract DE-AC02-76SF00515 The Linac Coherent Light Source II (LCLS-II) project requires the assembly, test, and installation of 37 cryomodules (CM) in order to deliver a 4 GeV CW electron beam to the FEL undulators for production of both hard and soft X-ray pulses at a repetition rate of up to 1 MHz. SRF cavity performance in the 30+ tested CM exceeds gradient and cryogenic dynamic heat-load requirements (set at 16 MV/m and 10 W resp). In this talk we present microphonics, shipping, magnetic-flux exclusion, and field emission performance. The US funding agency, DOE, has recently approved an additional 20 CM for the extension of LCLS-II to 8 GeV. This paper will also include initial cavity and heat-load performance results for the extension project, LCLS-II-HE.
	Slides MOFAA1 [30.146 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOFAA1
About •	paper received ※ 25 June 2019 paper accepted ※ 04 July 2019 issue date ※ 14 August 2019
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MOFAA3	The FRIB SC-Linac - Installation and Phased Commissioning	cryomodule, MMI, cavity, cryogenics	12
	J. Wei, H. Ao, S. Beher, B. Bird, N.K. Bultman, F. Casagrande, D. Chabot, W. Chang, S. Cogan, C. Compton, J. Curtin, K.D. Davidson, E. Daykin, K. Elliott, A. Facco, A. Fila, V. Ganni, A. Ganshyn, P.E. Gibson, T. Glasmacher, I. Grender, W. Hartung, L. Hodges, K. Holland, H.-C. Hseuh, A. Hussain, M. Ikegami, S. Jones, T. Kanemura, S.H. Kim, P. Knudsen, M.G. Konrad, J. LeTourneau, Z. Li, S.M. Lidia, G. Machicoane, P. Manwiller, F. Marti, T. Maruta, E.S. Metzgar, S.J. Miller, D.G. Morris, C. Nguyen, K. Openlander, P.N. Ostroumov, A.S. Plastun, J.T. Popielarski, L. Popielarski, J. Priller, M.A. Reaume, H.T. Ren, T. Russo, K. Saito, M. Shuptar, J.W. Stetson, D.R. Victory, R. Walker, X. Wang, J.D. Wenstrom, M. Wright, M. Xu, T. Xu, Y. Yamazaki, Q. Zhao, S. Zhao FRIB, East Lansing, Michigan, USA K. Dixon, M. Wiseman JLab, Newport News, Virginia, USA A. Facco INFN/LNL, Legnaro (PD), Italy K. Hosoyama KEK, Ibaraki, Japan M.P. Kelly ANL, Lemont, Illinois, USA R.E. Laxdal TRIUMF, Vancouver, Canada
	Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661. The Facility for Rare Isotope Beams (FRIB) superconducting (SC) driver linac is designed to accelerate all stable ions including uranium to energies above 200 MeV/u primarily with 46 cryomodules containing 324 quarter-wave resonators (QWR) and half-wave (HWR) resonators. With the newly commissioned helium refrigeration system supplying liquid helium to the QWR and solenoids, heavy ion beams including Ne, Ar, Kr and Xe were accelerated to the charge stripper location above 20 MeV/u with the first linac segment consisting of 15 cryomodules containing 10⁴ QWRs of β=0.041 and 0.085 and 39 solenoids. Installation of cryomodules with β=0.29 and 0.53 HWRs is proceeding in parallel. Development of β=0.65 elliptical resonators is on-going supporting the FRIB energy upgrade to 400 MeV/u. This paper summarizes the SC-linac installation and phased commissioning status that is on schedule and on budget to the FRIB project.
	Slides MOFAA3 [46.571 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOFAA3
About •	paper received ※ 23 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019
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MOP005	The Facility for Rare Isotope Beams Superconducting Cavity Production Status and Findings Concerning Surface Defects	cavity, SRF, niobium, status	31
	C. Compton NSCL, East Lansing, Michigan, USA H. Ao, J. Asciutto, K. Elliott, W. Hartung, S.H. Kim, E.S. Metzgar, S.J. Miller, J.T. Popielarski, L. Popielarski, K. Saito, T. Xu FRIB, East Lansing, Michigan, USA J. Craft SLAC, Menlo Park, California, 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), located on the campus of Michigan State University (MSU) will require 324 Superconducting Radio Frequency (SRF) cavities in the driver linac. Four types of cavities of two classes, quarter-wave (β=0.041 and 0.085) and half-wave (β=0.29 and 0.53), will be housed in 46 cryomodules. To date, FRIB has tested over 300 cavities in vertical Dewar tests as part of the certification procedures. Incoming cavities, fabricated in industry, are sequenced through acceptance inspection and checked for non-conformance. If accepted, the cavities are processed, assembled onto a vertical test stand, and cold tested. A large database of cavity surface images has been collected with the aid of a borescope camera. Borescope inspection is a standard step that is performed at incoming inspection, post-acid bulk etch, and after failed tests (if necessary) for each cavity, in order to locate any non-conformances. Findings of surface defects relating to degraded cavity performance will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP005
About •	paper received ※ 02 July 2019 paper accepted ※ 13 August 2019 issue date ※ 14 August 2019
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MOP019	Surface Preparation and Optimization of SC CH Cavities	cavity, operation, coupling, ECR	71
	P. Müller, M. Basten, M. Busch, T. Conrad, H. Podlech IAP, Frankfurt am Main, Germany K. Aulenbacher, F.D. Dziuba, M. Miski-Oglu HIM, Mainz, Germany W.A. Barth GSI, Darmstadt, Germany
	The Institute of Applied Physics (IAP) introduced the superconducting multi-gap CH-structure, which is mainly designed for low beta hadron acceleration. In 2017, a 217 MHz sc CH-structure was successfully tested with beam at GSI and multiple CH-structures are currently under development for the GSI cw linac. RF performance of all sc cavities are limited by the surface properties of the used material. Therefore, sufficient surface preparation and optimization is necessary to achieve optimal performance. Presently as standard procedure BCP and HPR is used for CH-cavities. Several surface treatments will be applied to the very first CH-prototype, a 360 MHz, 19-cell cavity. Prior to the first treatment, the status of the cavity was examined, including leak tests and performance tests at 4 and 2 K. This paper presents the performance development of a sc CH cavity depending on different preparation methods.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP019
About •	paper received ※ 23 June 2019 paper accepted ※ 05 July 2019 issue date ※ 14 August 2019
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MOP022	Superconducting RF Cavity Materials Research at the S-DALINAC	cavity, niobium, SRF, simulation	74
	R. Grewe, L. Alff, M. Arnold, J. Conrad, S. Flege, M. Major, N. Pietralla TU Darmstadt, Darmstadt, Germany F. Hug IKP, Mainz, Germany
	Funding: Supported by BMBF Through 05H18RDRB2 Current state-of-the-art superconducting rf (srf) accelerators are mostly using cavities made of high RRR bulk niobium (Nb). The maximum field gradients and quality factors (Q₀) of these cavities are basically reached now. To further increase the srf cavity properties for future accelerator facilities, research of new materials for srf cavity applications is necessary. The current research at the S-DALINAC* is focused on the development of bake-out procedures of Nb samples and cavities in nitrogen (N) atmosphere of up to 100 mbar to nucleate the delta-phase (d-phase) of the Nb-N binary system. The d-phase has superconducting properties which exceed the properties of bulk Nb. This makes the d-phase attractive for srf applications. The vertical test cryostat (vt) at the S-DALINAC has been upgraded and recommissioned to allow investigations of the quality factor and accelerating field gradients of cavities before and after bake-out. The vt upgrade includes a newly developed variable input coupling to allow matching of the external q-factor (Qex) to Q₀. The results of the ongoing research of the nitrogen atmosphere bake-out procedures and the upgrade of the vt will be presented. *N. Pietralla, Nuclear Physics News, Vol. 28, No. 2, 4 (2018)
	Poster MOP022 [1.759 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP022
About •	paper received ※ 21 June 2019 paper accepted ※ 01 July 2019 issue date ※ 14 August 2019
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MOP033	The Beam Dynamics Updates of the Fermilab PIP-II 800 MeV Superconducting Linac	SRF, cavity, optics, emittance	123
	A. Saini, V.P. Yakovlev Fermilab, Batavia, Illinois, USA E. Pozdeyev FRIB, East Lansing, Michigan, USA
	The Proton Improvement Plan (PIP) -II is a high intensity proton facility being developed to support a neutrino program over the next two decades at Fermilab. At its core is the design and construction of a Continuous Wave compatible superconducting radio frequency linear accelerator that would accelerate an average beam current of 2 mA up to 800 MeV. This paper presents recent updates in the beam dynamics leading to a reliable and robust linac design and simplifying the cryo-module assembly.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP033
About •	paper received ※ 23 June 2019 paper accepted ※ 01 July 2019 issue date ※ 14 August 2019
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MOP034	European XFEL: Accelerating Module Repair at DESY	cavity, FEL, SRF, operation	127
	D. Kostin, J. Eschke, K. Jensch, N. Krupka, D. Reschke, S. Saegebarth, J. Schaffran, M. Schalwat, P. Schilling, M. Schmökel, S. Sievers, N. Steinhau-Kühl, E. Vogel, H. Weise, M. Wiencek, B. van der Horst DESY, Hamburg, Germany
	The European XFEL is in operation since 2017. The design projected energy of 17.5 GeV was reached, even with the last 4 main linac accelerating modules not yet installed. 2 out of 4 not installed modules did suffer from strong cavity performance degradation, namely increased field emission, and required surface processing. The first of two modules is reassembled and tested. The module test results confirm a successful repair action. The module repair and test steps are described together with cavities performance evolution.
	Poster MOP034 [1.863 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP034
About •	paper received ※ 17 June 2019 paper accepted ※ 29 June 2019 issue date ※ 14 August 2019
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MOP036	Microphonics Suppression Study in ARIEL e-Linac Cryomodules	cavity, cryomodule, GUI, pick-up	136
	Y. Ma, K. Fong, J.J. Keir, D. Kishi, S.R. Koscielniak, D. Lang, R.E. Laxdal, S.L. Liu, R.S. Sekhon, X. Wang TRIUMF, Vancouver, Canada
	Now the stage of the 30 MeV portion of ARIEL (The Advanced Rare Isotope Laboratory) e-Linac (1.3 GHz, SRF) is under commissioning which includes an injector cryomodule (ICM) with a single nine-cell cavity and the 1st accelerator cryomodule (ACM1) with two cavities configuration. The two ACM1 cavities are driven by a single klystron with vector-sum control and running in CW mode. We have observed a ponderomotive instability in ACM1 driven by the Lorentz force and seeded through microphonics that impacts beam stability [1-5]. Extensive damping has been implemented during a recent shut-down. The beam test results show 20 MeV acceleration gain can be reached by ACM1. A fast piezoelectric (Pie-zo) tuner is under development to allow a fast tuning compensation for the e-Linac cavities. In this paper, the progress of the microphonics suppression of Cryomod-ules is presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP036
About •	paper received ※ 24 June 2019 paper accepted ※ 01 July 2019 issue date ※ 14 August 2019
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MOP045	The LCLS-II HE High Q and Gradient R&D Program	cavity, SRF, cryomodule, niobium	154
	D. Gonnella, S. Aderhold, A. Burrill, G.R. Hays, T.O. Raubenheimer, M.C. Ross SLAC, Menlo Park, California, USA D. Bafia, M. Checchin, A. Grassellino, M. Martinello, A.S. Romanenko Fermilab, Batavia, Illinois, USA M. Ge, M. Liepe, S. Posen Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA A.D. Palczewski, C.E. Reece JLab, Newport News, Virginia, USA
	Funding: US DOE and the LCLS-II HE Project The LCLS-II HE project is a high energy upgrade to the superconducting LCLS-II linac. It consists of adding twenty additional 1.3 GHz cryomodules to the linac, with cavities operating at a gradient of 20.8 MV/m with a Q₀ of 2.7·10¹⁰. Performance of LCLS-II cryomodules has suggested that operations at this high of a gradient will not be achievable with the existing cavity recipe employed. Therefore a research program was developed between SLAC, Fermilab, Thomas Jefferson National Accelerator Facility, and Cornell University in order to improve the cavity processing method of the SRF cavities and reach the HE goals. This program explores the doping regime beyond what was done for LCLS-II and also has looked to further developed nitrogen-infusion. Here we will summarize the results from this R\&D program, showing significant improvement on both single-cell and 9-cell cavities compared with the original LCLS-II cavity recipe.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP045
About •	paper received ※ 25 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019
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MOP050	Modular Power Couplers for 217 MHz Superconducting CH-Cavities	cavity, Windows, heavy-ion, simulation	168
	J. List, K. Aulenbacher, W.A. Barth, C. Burandt, F.D. Dziuba, V. Gettmann, T. Kürzeder, S. Lauber, M. Miski-Oglu HIM, Mainz, Germany K. Aulenbacher, W.A. Barth, C. Burandt, V. Gettmann, M. Heilmann, T. Kürzeder, S. Lauber, J. List, M. Miski-Oglu, A. Schnase, S. Yaramyshev GSI, Darmstadt, Germany K. Aulenbacher, F.D. Dziuba, S. Lauber, J. List IKP, Mainz, Germany M. Basten, M. Busch, H. Podlech, M. Schwarz IAP, Frankfurt am Main, Germany
	The HELmholtz LInear ACcelerator (HELIAC) is being developed by a collaboration of HIM, GSI and the Goethe University of Frankfurt. It is a superconducting (sc), continuous wave (cw) heavy ion linac that comprises novel Crossbar H-mode (CH) cavities. In April 2017 and November/December 2018 the first sc CH-cavity of the linac was tested with beam. The first operations of the cavity showed, that the prototype of the rf power coupler needs to be further improved. A new version of the coupler is being designed at the HIM. Further development will mainly be focused on the heat input into the cryostat caused by the coupler. Also the coupler will have a modular design. This improves the accessibility and maintenance of the coupler. Various cryogenic and rf tests are foreseen, to provide a reliable, fail-safe coupler for the HELIAC. For an enhanced coupler test stand a movable reflector has been designed and built. With its movable semi-reflective element, it allows to operate the test stand in a resonance mode. In addition, the movable reflector can vary the coupling factor. This contribution discusses the recent coupler R&D for the HELIAC.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP050
About •	paper received ※ 21 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019
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MOP051	3.9 GHz SRF Production Cavities for LCLS-II	cavity, cryomodule, radiation, vacuum	173
	S. Aderhold, A. Burrill SLAC, Menlo Park, California, USA D.J. Bice, C.M. Ginsburg, C.J. Grimm, T.N. Khabiboulline, O.S. Melnychuk, D.A. Sergatskov, N. Solyak, G. Wu Fermilab, Batavia, Illinois, USA
	Funding: This work was supported by the US DOE and the LCLS-II Project. The main part of the SRF linac for the Linac Coherent Light Source II (LCLS-II) at SLAC will consist of 35 cryomodules with superconducting RF cavities operating at 1.3 GHz. In addition, two cryomodules with 3.9 GHz cavities will be installed and help to linearize the longitudinal phase space of the beam. During the design verification phase, four prototype 9-cell 3.9 GHz cavities had been built by industry and then processed, including chemical surface removal and heat treatment, and tested at Fermi National Accelerator Laboratory. Based on the resulting cavity treatment recipe, 24 cavities (for two cryomodules to be installed in the linac and one spare cryomodule) have been built by industry and tested at Fermilab prior to cryomodule string assembly. We present an overview of the cavity production and the results of the vertical acceptance tests for the LCLS-II 3.9 GHz cavities.
	Poster MOP051 [1.015 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP051
About •	paper received ※ 02 July 2019 paper accepted ※ 03 July 2019 issue date ※ 14 August 2019
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MOP054	Fabrication of 3.0-GHz Single-cell Cavities for Thin-film Study	cavity, SRF, MMI, FEL	177
	T. Saeki, H. Hayano, H. Inoue, R. Katayama, T. Kubo KEK, Ibaraki, Japan F.E. Hannon, R.A. Rimmer, A-M. Valente-Feliciano JLab, Newport News, Virginia, USA H. Ito Sokendai, Ibaraki, Japan Y. Iwashita, H. Tongu Kyoto ICR, Uji, Kyoto, Japan
	Funding: This work is supported by JSPS KAKENHI JP17H04839, JSPS KAKENHI JP26600142, Japan-US Research Collaboration Program, and the Collaborative Research Program of ICR Kyoto Univ. (2018-13). We fabricated 3.0-GHz single-cell cavities with Cu and Nb materials for testing thin-film creations on the inner surface of the cavities in collaboration between Jefferson Laboratory (JLab) and KEK. The cavity was designed at JLab. According to the design of cavity, the press-forming dies and trimming fixtures for the cavity-cell were also designed and fabricated at JLab. These dies and trimming fixtures were transported to KEK, and the rest of fabrication processes were done at KEK. Finally nine Cu 3.0-GHz single-cell cavities and six Nb 3.0-GHz single-cell cavities were fabricated. Two Cu 3.0-GHz single-cell cavities were mechanically polished at Jlab. All of these cavities will be utilized for the tests of various thin-film creations at JLab and KEK. This presentation describes details of the fabrication of these cavities.
	Poster MOP054 [1.203 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP054
About •	paper received ※ 05 July 2019 paper accepted ※ 13 August 2019 issue date ※ 14 August 2019
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MOP055	Fabrication and Performance of Superconducting Quarter-Wavelength Resonators for SRILAC	cavity, operation, cryomodule, acceleration	182
	K. Suda, O. Kamigaito, K. Ozeki, N. Sakamoto, Y. Watanabe, K. Yamada 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
	A new superconducting booster linac (SRILAC) at the RIKEN heavy-ion linac is under construction. Ten 73-MHz low-beta quarter-wavelength resonators (QWRs) that operate at 4 K have been fabricated from pure niobium sheets. The cavity parts were assembled by electron beam welding. The resonant frequency for each cavity was adjusted by changing the lengths of the straight sections before welding. The performance and frequency were evaluated by vertical tests. All the cavities exceeded the design specifications of Q₀ = 1x10⁹ and E_acc = 6.8 MV/m. Details of the fabrication and frequency tuning as well as the performance of the cavities are reported.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP055
About •	paper received ※ 17 July 2019 paper accepted ※ 13 August 2019 issue date ※ 14 August 2019
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MOP057	Electropolishing of PIP-II Low Beta Cavity Prototypes	cavity, cathode, experiment, FEL	194
	M. Bertucci, A. Bosotti, A. D’Ambros, P. Michelato, L. Monaco, C. Pagani, R. Paparella, D. Sertore INFN/LASA, Segrate (MI), Italy A. Gresele, A. Visentin Ettore Zanon S.p.A., Nuclear Division, Schio, Italy C. Pagani Università degli Studi di Milano & INFN, Segrate, Italy D. Rizzetto, M. Rizzi Ettore Zanon S.p.A., Schio, Italy
	We present the upgrade of the EP facility for the surface treatment of PIP-II low beta cavities. The main process parameters, such as voltage, treatment time, acid throughput and cathode geometry, already optimized on the previous experience of 1.3 GHz Tesla-shape cavities, are discussed taking into account the different cavity size and geometry. The first surface treatments have been performed at Ettore Zanon SpA on single cell cavity prototypes in order to reach good final surface finishing and the required thickness removal. In the meantime, the upgrade of the system for the treatment of multicell PIP-II prototype cavities is presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP057
About •	paper received ※ 23 June 2019 paper accepted ※ 02 July 2019 issue date ※ 14 August 2019
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MOP060	INFN-LASA for the PIP-II Project	cavity, niobium, SRF, interface	205
	R. Paparella, M. Bertucci, A. Bignami, A. Bosotti, M. Chiodini, A. D’Ambros, P. Michelato, L. Monaco, D. Sertore INFN/LASA, Segrate (MI), Italy J.F. Chen SARI-CAS, Pudong, Shanghai, People’s Republic of China C. Pagani Università degli Studi di Milano & INFN, Segrate, Italy L. Sagliano ESS, Lund, Sweden
	INFN-LASA joined the international effort for the PIP-II project in Fermilab to build the 650 MHz superconducting cavities realizing the low-beta section of the 800 MeV proton linac. After developing the electro-magnetic and mechanical design, INFN-Milano started the prototyping phase by producing five single-cells and two complete 5-cells cavities. This paper reports the status of PIP-II activities at INFN-LASA summarizing manufacturing experience and preliminary experimental results.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP060
About •	paper received ※ 24 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019
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MOP065	Upgrade of the S-DALINAC Injector Capture Section	cavity, MMI, gun, target	227
	S. Weih, M. Arnold, J. Enders, N. Pietralla TU Darmstadt, Darmstadt, Germany D.B. Bazyl, H. De Gersem, W.F.O. Müller TEMF, TU Darmstadt, Darmstadt, Germany
	Funding: Work supported by DFG through GRK 2128 "AccelencE" The superconducting injector section of the S-DALINAC (superconducting Darmstadt linear electron accelerator) [1] constists of two cryomodules with three 3-GHz SRF cavities in total. The first cavity of this pre-accelerator is currently a 5-cell structure designed for relativistic particle velocities. Since the gun delivers a 250 keV beam (β=0.74), this cavity is not suited for an efficient capture of the low-energy electron bunches provided by the normal-conducting section of the injector. Beam dynamics simulations and operational experience have shown a large low-energy tail in the phase-space distribution of the bunch downstream of the injector, which arises from the large phase-slippage during the capture in the 5-cell. It is therefore intended to replace the cavity with a beta-adapted 6-cell, re-using most of the cryostat parts. This contribution presents the status of the injector upgrade and the layout and manufacturing status of the new cavity. *N. Pietralla, Nuclear Physics News, Vol. 28, No. 2, 4 (2018)
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP065
About •	paper received ※ 21 June 2019 paper accepted ※ 02 July 2019 issue date ※ 14 August 2019
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MOP081	Considerations for Efficient RF Operation for the Advanced cw-Linac Demonstrator at GSI	cavity, cryomodule, heavy-ion, SRF	267
	C. Burandt, K. Aulenbacher, W.A. Barth, F.D. Dziuba, V. Gettmann, T. Kürzeder, S. Lauber, J. List, M. Miski-Oglu, S. Yaramyshev HIM, Mainz, Germany K. Aulenbacher, W.A. Barth, C. Burandt, F.D. Dziuba, V. Gettmann, M. Heilmann, T. Kürzeder, S. Lauber, J. List, M. Miski-Oglu, A. Schnase, S. Yaramyshev GSI, Darmstadt, Germany K. Aulenbacher, F.D. Dziuba, S. Lauber, J. List IKP, Mainz, Germany M. Basten, M. Busch, H. Podlech, M. Schwarz IAP, Frankfurt am Main, Germany
	The FAIR@GSI accelerator facility will require the GSI-UNILAC to provide short heavy ion pulses of highest intensity at low repetition rate for injection into the 18 Tm synchrotron SIS18. However, successful physics programs like SHE (Super Heavy Elements) rely on the UNILAC providing for heavy ion beams of high average current and high duty factor. In the next future, a dedicated super-conducting (sc) cw-Linac should therefore deliver cw beams to the experiments associated with those programs. As a first step towards this goal, beam tests with a single sc Cross-bar H-mode (CH) cavity were successfully conducted in 2017/2018. Within the scope of an Advanced Demonstrator project, current activities now aim at a beam test of a full cryomodule with three sc CH cavities and a sc rebuncher. Given a limited amount of rf power available per cavity and the necessity to accelerate different ion species with different mass-to-charge ratios, the loaded quality factor Q of the different resonators has to be chosen very carefully. This contribution discusses the simulations performed in this context.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP081
About •	paper received ※ 21 June 2019 paper accepted ※ 29 June 2019 issue date ※ 14 August 2019
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MOP087	IFMIF Resonators Development and Performance	cavity, SRF, cryomodule, solenoid	293
	G. Devanz, M. Baudrier, P. Carbonnier, F. Éozénou, E. Fayette, D. Roudier, P. Sahuquet, C. Servouin CEA-DRF-IRFU, France N. Bazin, S. Chel, L. Maurice CEA-IRFU, Gif-sur-Yvette, France
	The prototype IFMIF cryomodule encloses eight superconducting 175 MHz beta 0.09 Half-Wave Resonators (HWR). They are designed together with the power coupler to accelerate a high intensity deuteron beam (125 mA) from to 5 to 9 MeV. One prototype HWR and the 8 cavities to be hosted in the cryomodule have been manufactured, prepared and tested. The paper describes the phases of the cavities development, including fabrication, processing, and RF resonant frequency management. We focus on the results of the RF tests which have been performed for all bare and jacketed HWRs in a vertical cryostat.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP087
About •	paper received ※ 23 June 2019 paper accepted ※ 03 July 2019 issue date ※ 14 August 2019
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MOP097	Preliminary Design of the IFMIF-DONES Superconducting Linac	cavity, cryomodule, SRF, neutron	311
	T. Plomion, N. Bazin, N. Chauvin, G. Devanz, J. Plouin, K. Romieu CEA-DRF-IRFU, France S. Chel CEA-IRFU, Gif-sur-Yvette, France
	The linear accelerator for the DONES facility (DEMO oriented neutron source) will serve as a neutron source for the assessment of materials damage in future fusion reactors. The DONES accelerator, which is based on the design of LIPac (Linear IFMIF Prototype Accelerator, which is under construction in Rokkasho, Japan) will accelerate deuterons from 100 keV up to 40 MeV at full CW current of 125 mA. This paper will present the preliminary design of the superconducting linac which is based on five cryomodules.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP097
About •	paper received ※ 21 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019
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TUP002	Modeling of Superconducting Spoke Cavity with its Control Loops Systems for the MYRRHA Linac Project	cavity, LLRF, cryomodule, feedback	387
	M. Dominiczak ACS, Orsay, France F. Bouly LPSC, Grenoble Cedex, France N. Gandolfo, C. Joly Université Paris-Saclay, CNRS/IN2P3, IJCLab, 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)
	Poster TUP002 [1.335 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP002
About •	paper received ※ 23 June 2019 paper accepted ※ 04 July 2019 issue date ※ 14 August 2019
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TUP004	Latest Cryogenic Test Results of the Superconducting β=0.069 CH-cavities for the HELIAC-project	cavity, vacuum, cryomodule, heavy-ion	392
	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 TUP004 [0.958 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP004
About •	paper received ※ 22 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019
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TUP005	Cavity Designs for the CH3 to CH11 of the Superconducting Heavy Ion Accelerator HELIAC	cavity, heavy-ion, resonance, electron	396
	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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP005
About •	paper received ※ 19 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019
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TUP007	Electromagnetic Design of the Prototype Spoke Cavity for the JAEA-ADS Linac	cavity, SRF, proton, superconductivity	399
	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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP007
About •	paper received ※ 02 July 2019 paper accepted ※ 04 July 2019 issue date ※ 14 August 2019
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TUP013	Non-Evaporative Getter-Based Differential Pumping System for SRILAC at RIBF	vacuum, SRF, cavity, operation	419
	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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP013
About •	paper received ※ 03 July 2019 paper accepted ※ 14 August 2019 issue date ※ 14 August 2019
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TUP023	Experience of LCLS-II Cavities Radial Tuning at DESY	cavity, HOM, SRF, FEL	456
	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 TUP023 [0.521 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP023
About •	paper received ※ 23 June 2019 paper accepted ※ 01 July 2019 issue date ※ 14 August 2019
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TUP028	Development of Vertical Electropolishing Facility for Nb 9-Cell Cavity (3)	cavity, scattering, cathode, controls	470
	Y.I. Ida, V. Chouhan, K.N. Nii 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 TUP028 [0.444 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP028
About •	paper received ※ 24 June 2019 paper accepted ※ 29 June 2019 issue date ※ 14 August 2019
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TUP033	Modal Analysis of the EXFEL 1.3 GHz Cavity and Cryomodule Main Components and Comparison with Measured Data	cavity, cryomodule, FEL, vacuum	488
	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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP033
About •	paper received ※ 18 June 2019 paper accepted ※ 01 July 2019 issue date ※ 14 August 2019
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TUP037	Construction of Superconducting Linac Booster for Heavy-Ion Linac at RIKEN Nishina Center	cryomodule, vacuum, controls, booster	502
	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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP037
About •	paper received ※ 02 July 2019 paper accepted ※ 04 July 2019 issue date ※ 14 August 2019
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TUP042	Measurement of Mechanical Vibration of SRILAC Cavities	cavity, niobium, ECR, cryomodule	513
	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 TUP042 [6.957 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP042
About •	paper received ※ 27 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019
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TUP064	Flashover on RF Window of HWR SRF Cavity	cavity, pick-up, electron, SRF	597
	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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP064
About •	paper received ※ 23 June 2019 paper accepted ※ 04 July 2019 issue date ※ 14 August 2019
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TUP066	New Design of SSR2 Spoke Cavity for PIP II SRF Linac	cavity, quadrupole, multipactoring, HOM	600
	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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP066
About •	paper received ※ 21 June 2019 paper accepted ※ 01 July 2019 issue date ※ 14 August 2019
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TUP084	Testing of the Piezo-actuators at High Dynamic Rate Operational Conditions	SRF, cavity, operation, vacuum	656
	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 TUP084 [3.168 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP084
About •	paper received ※ 23 June 2019 paper accepted ※ 04 July 2019 issue date ※ 14 August 2019
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TUP086	Frequency Tuning System Based on Mobile Plungers For Superconductive Coaxial Half Wave Resonators	cavity, simulation, SRF, vacuum	664
	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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP086
About •	paper received ※ 22 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019
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TUP087	Development and Performances of Spoke Cavity Tuner for MYRRHA Linac Project	cavity, controls, simulation, operation	667
	N. Gandolfo, S. Blivet, P. Duchesne, D. Le Dréan Université Paris-Saclay, CNRS/IN2P3, IJCLab, 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 TUP087 [2.367 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP087
About •	paper received ※ 01 July 2019 paper accepted ※ 03 July 2019 issue date ※ 14 August 2019
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TUP089	FRIB LS1 Cryomodule’s Solenoid Commissioning	solenoid, cryomodule, MMI, controls	671
	M. Xu, H. Ao, B. Bird, R. Bliton, C. Compton, J. Curtin, L. Hodges, K. Holland, S.J. Miller, K. Saito, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP089
About •	paper received ※ 24 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019
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TUP093	Summary of FRIB Cavity Processing in the SRF Coldmass Processing Facility and Lessons Learned	cavity, niobium, SRF, controls	680
	E.S. Metzgar, B.W. Barker, K. Elliott, W. Hartung, L. Popielarski, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP093
About •	paper received ※ 22 June 2019 paper accepted ※ 29 June 2019 issue date ※ 14 August 2019
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TUP096	Optimization of Clean Room Infrastructure and Procedure During LCLS-II Cryomodule Production at Fermilab	cavity, cryomodule, vacuum, detector	695
	G. Wu, S.D. Adams, T.T. Arkan, M.A. Battistoni, D.J. Bice, 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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP096
About •	paper received ※ 23 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019
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TUP098	Preparation for the Advanced Demonstrator Testing at GSI	cavity, solenoid, cryomodule, heavy-ion	698
	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.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP098
About •	paper received ※ 22 June 2019 paper accepted ※ 01 July 2019 issue date ※ 14 August 2019
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TUP101	LCLS-II Cryomodules Production Experience and Lessons Learned at Fermilab	cryomodule, vacuum, cavity, FEL	709
	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 TUP101 [0.834 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP101
About •	paper received ※ 20 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019
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TUP106	Mechanical Tuner for a 325 MHz Balloon Single Spoke Resonator	cavity, cryomodule, simulation, operation	730
	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 TUP106 [1.089 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP106
About •	paper received ※ 23 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019
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WETEA3	Status of the IFMIF/EVEDA Superconducting Linac	cavity, SRF, solenoid, cryomodule	735
	N. Bazin, G. Devanz, H. Jenhani, O. Piquet CEA-DRF-IRFU, France S. Chel CEA-IRFU, Gif-sur-Yvette, France T. Ebisawa QST, Aomori, Japan G. Phillips F4E, Germany D. Regidor, F. Toral CIEMAT, Madrid, Spain
	The IFMIF accelerator aims to provide an accelerator-based D-Li neutron source to produce high intensity high energy neutron flux to test samples as possible candidate materials to a full lifetime of fusion energy reactors. A prototype of the low energy part of the accelerator (LIPAc) is under construction at Rokkasho Fusion Institute in Japan. It includes one cryomodule containing 8 half-wave resonators (HWR) operating at 175 MHz and eight focusing solenoids. The talk will cover the progress of developments in the IFMIF/EVEDA cryomodule: the qualification of 8 cavities, the RF conditioning results of 8 high-power couplers, the manufacturing and test of the 8 superconducting solenoids and the equivalent operational equivalent tests performed at Saclay. The assembling status of the cryomodule at Rokkasho site will also be presented.
	Slides WETEA3 [11.091 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-WETEA3
About •	paper received ※ 20 June 2019 paper accepted ※ 29 June 2019 issue date ※ 14 August 2019
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WETEB1	Development of Superconducting Quarter-Wave Resonator and Cryomodule for Low-Beta Ion Accelerators at RIKEN Radioactive Isotope Beam Factory	cavity, cryomodule, vacuum, SRF	750
	N. Sakamoto, T. Dantsuka, M. Fujimaki, H. Imao, O. Kamigaito, K. Kusaka, H. Okuno, K. Ozeki, K. Suda, A. Uchiyama, T. Watanabe, Y. Watanabe, K. Yamada 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
	A prototype cryomodule with a superconducting quarter- wave resonator (SC QWR) has been developed at RIKEN Radioactive Isotope Beam Factory (RIBF). During the last SRF conference, we presented the performance of our first SC QWR and the first cool-down test of its cryomodule. Since then, we have continued our efforts to improve cavity performance and succeeded in recovering deteriorated Q₀. In this paper, we report what we constructed and learned from the prototype, including design issues with the cavity and its cryomodule. Design issues related to the new SC QWRs and their cryomodules for the SC linac booster of the RIKEN Heavy-Ion Linac (RILAC) are described as well.
	Slides WETEB1 [120.252 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-WETEB1
About •	paper received ※ 24 June 2019 paper accepted ※ 05 July 2019 issue date ※ 14 August 2019
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WETEB6	Active Suppression of Microphonics Detuning in High QL Cavities	cavity, controls, resonance, SRF	776
	N. Banerjee, G.H. Hoffstaetter, M. Liepe, P. Quigley Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: This work was performed through the support of New York State Energy Research and Development Agency (NYSERDA). SRF 2019 provided travel support in the form of a student grant. Accelerators operating with low beam loading such as Energy Recovery Linacs (ERL) greatly benefit from using SRF cavities operated at high loaded quality factors, since it leads to lower RF power requirements. However, large microphonics detuning several times the operating bandwidth of the cavities severely limit the maximum accelerating fields which can be sustained in a stable manner. In this talk, I will describe an active microphonics control technique based on the narrow band Active noise Control (ANC) algorithm which we have used in CBETA, a multi-turn SRF ERL being commissioned at Cornell University. I will describe its stability and performance during beam operations of CBETA with consistent reduction of peak detuning by almost a factor of 2 on multiple cavities.
	Slides WETEB6 [10.296 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-WETEB6
About •	paper received ※ 23 June 2019 paper accepted ※ 29 June 2019 issue date ※ 14 August 2019
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WETEB7	A Ferroelectric Fast Reactive Tuner for Superconducting Cavities	cavity, controls, experiment, superconducting-cavity	781
	N.C. Shipman, J. Bastard, M.R. Coly, F. Gerigk, A. Macpherson, N. Stapley CERN, Geneva, Switzerland I. Ben-Zvi BNL, Upton, New York, USA G. Burt, A. Castilla Lancaster University, Lancaster, United Kingdom C.-J. Jing, A. Kanareykin Euclid TechLabs, LLC, Solon, Ohio, USA S. Kazakov Fermilab, Batavia, Illinois, USA E. Nenasheva Ceramics Ltd., St. Petersburg, Russia
	A prototype FerroElectric Fast Reactive Tuner (FE-FRT) for superconducting cavities has been developed, which allows the frequency to be controlled by application of a potential difference across a ferroelectric residing within the tuner. This technique has now become practically feasible due to the recent development of a new extremely low loss ferroelectric material. In a world first, CERN has tested the prototype FE-FRT with a superconducting cavity, and frequency tuning has been successfully demonstrated. This is a significant first step in the development of an entirely new class of tuner. These will allow electronic control of cavity frequencies, by a device operating at room temperature, within timescales that will allow active compensation of microphonics. For many applications this could eliminate the need to use over-coupled fundamental power couplers, thus significantly reducing RF amplifier power.
	Slides WETEB7 [21.570 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-WETEB7
About •	paper received ※ 23 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019
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THFUA2	Evaluation of the Superconducting Characteristics of Multi-Layer Thin-Film Structures of NbN and SiO₂ on Pure Nb Substrate	experiment, DTL	807
	R. Katayama, H. Hayano, T. Kubo, T. Saeki KEK, Ibaraki, Japan C.Z. Antoine CEA-IRFU, Gif-sur-Yvette, France H. Ito Sokendai, Ibaraki, Japan R. Ito ULVAC, Inc, Chiba, Japan Y. Iwashita, H. Tongu Kyoto ICR, Uji, Kyoto, Japan T. Nagata ULVAC, Inc., Tsukuba, Japan
	In recent years, it has been pointed out that the maximum accelerating gradient of a superconducting RF cavity can be increased by coating the inner surface of the cavity with a multilayer thin-film structure consisting of alternating insulating and superconducting layers. In this structure, the principal parameter that limits the performance of the cavity is the critical magnetic field or effective Hc1 at which vortices begin penetrating into the superconductor layer. This is predicted to depend on the combination of the film thickness. We made samples that have a NbN/SiO₂ thin-film structure on a pure Nb substrate with several layers of NbN film deposited using DC magnetron sputtering method. Here, we report the measurement results of effective Hc1 of NbN/SiO₂(30 nm)/Nb multilayer samples with thicknesses of NbN layers in the range from 50 nm to 800 nm by using the third-harmonic voltage method. Experimental results show that an optimum thickness exists, which increases the effective Hc1 by 23.8 %.
	Slides THFUA2 [2.333 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THFUA2
About •	paper received ※ 03 July 2019 paper accepted ※ 05 July 2019 issue date ※ 14 August 2019
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THP023	RF Commissioning of the CBETA Main Linac Cryomodule	cavity, operation, LLRF, controls	881
	N. Banerjee, J. Dobbins, G.H. Hoffstaetter, R.P.K. Kaplan, M. Liepe, C.W. Miller, P. Quigley, E.N. Smith, V. Veshcherevich Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: This work was performed through the support of New York State Energy Research and Development Agency (NYSERDA). The Cornell BNL ERL Test Accelerator (CBETA) employs a superconducting Main Linac Cryomodule in order to perform multi-turn energy recovery operation. Optimizing the field stability of the low bandwidth SRF cavities in the presence of microphonics with limited available RF power is a challenging task. Despite of this, the Main Linac Cryomodule has been successfully used in CBETA to impart a maximum energy gain of 54 MeV, well above the energy gain requirement of CBETA. In this paper, we present an overview of our RF commissioning procedure including automatic coarse tuning, measurement of DAC and phase offsets. We further detail our microphonics measurements from our most recent run period.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP023
About •	paper received ※ 23 June 2019 paper accepted ※ 29 June 2019 issue date ※ 14 August 2019
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THP032	SRF Gun and SRF Linac Driven THz at ELBE Successfully in User Operation	gun, SRF, radiation, electron	915
	R. Xiang, A. Arnold, P.E. Evtushenko, S. Kovalev, U. Lehnert, P.N. Lu, S. Ma, P. Michel, P. Murcek, A.A. Ryzhov, J. Schaber, Ch. Schneider, J. Teichert HZDR, Dresden, Germany H. Vennekate RI Research Instruments GmbH, Bergisch Gladbach, Germany I. Will MBI, Berlin, Germany
	Funding: The work was partly supported by the German Federal Ministry of Education and Research (BMBF) grant 05K12CR1 and Deutsche Forschungsgemeinschaft (DFG) project (XI 10⁶/2-1). The first all-SRF accelerator driven THz source has been operated as a user facility since 2018 at ELBE radiation center. The CW electron beam is extracted from SRF gun II, accelerated to relativistic energies and compressed to sub-ps length in the ELBE SRF linac with a chicane. THz pulses are produced by pass-ing the short electron bunches through a diffraction radiator (CDR) and an undulator. The coherent THz power increases quadratically with bunch charge. The pulse energy up to 10 µJ at 0.3 THz with 100 kHz has been generated.
	Poster THP032 [1.207 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP032
About •	paper received ※ 02 July 2019 paper accepted ※ 04 July 2019 issue date ※ 14 August 2019
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THP033	Cryogenic Systems Studies for the MINERVA 100 MeV Proton SC LINAC Project	cryogenics, cavity, cryomodule, proton	918
	O. Kochebina, F. Dieudegard, T. Junquera Accelerators and Cryogenic Systems, Orsay, France D. Vandeplassche SCK•CEN, Mol, Belgium
	The construction of the first phase of the MYRRHA project (MINERVA: 100 MeV-4 mA proton Linac) was recently decided by the Belgium Government. In the long term, the MYRRHA project plans to construct an ADS demonstrator for the transmutation of long-lived radioactive waste. It will include a subcritical reactor of 100 MW thermal power and a CW proton Linac accelerator (600 MeV-4 mA). The main challenge of this Linac is an extremely high reliability performance to limit stresses and long restart procedures of the reactor. The MINERVA Linac includes 30 cryomodules housing 60 Single-Spoke SC cavities. A cryomodule prototype with its valve box is under construction at IPNO institute. The cavities operate at 352 MHz in a superfluid Helium bath at 2K. Therefore, a reliable SC Linac Cryogenic System is essential. This article presents the preliminary studies in this subject including the analysis of high thermal loads induced by the CW mode operation of cavities (950 W@2 K per cryomodule). A Cryogenic Refrigerator with an equivalent power capacity of 2645 W @4.5 K (3970 W with 1.5 overcapacity factor) is proposed. The constrains for the He distribution in the Linac tunnel are also discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP033
About •	paper received ※ 23 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019
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THP053	Analysis of the Results of the Tests of IFMIF Accelerating Units	cavity, cryomodule, SRF, vacuum	992
	N. Bazin, S. Chel, M. Desmons, G. Devanz, H. Jenhani, O. Piquet CEA-DRF-IRFU, France
	The prototype IFMIF-EVEDA cryomodule encloses eight superconducting 175 MHz β=0.09 Half-Wave Resonators (HWR). They are designed together with the power coupler to accelerate a high intensity deuteron beam (125 mA) from to 5 to 9 MeV. Two cavity packages, complete with tuning system and power couplers, have been tested in a dedicated horizontal test cryostat - SaTHoRI (Satellite de Tests HOrizontal des Résonateurs IFMIF). The successful operational equivalent tests and tuning of the SRF accelerating units is reported.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP053
About •	paper received ※ 21 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019
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THP059	RF Incoming Inspection of 1.3 GHz Cryomodules for LCLS-II at SLAC National Accelerator Laboratory	cryomodule, cavity, HOM, controls	1014
	S. Aderhold, C. Adolphsen, A. Burrill, D. Gonnella, J. Nelson SLAC, Menlo Park, California, USA
	Funding: This work was supported by the US DOE and the LCLS-II Project. The main part of the SRF linac for the Linac Coherent Light Source II (LCLS-II) at SLAC National Accelerator Laboratory will consist of 35 cryomodules with superconducting RF cavities operating at 1.3 GHz. The cryomodules are assembled and tested at Fermi National Accelerator Laboratory and Thomas Jefferson National Accelerator Facility. Following the transport to SLAC, the cryomodules undergo several incoming inspection steps before ultimately being moved to the tunnel for installation in the linac. The RF part of the incoming inspection covers measurements of a number of parameters like cavity frequency spectrum, notch filter frequency of the higher order mode couplers and external quality factor Q_ext of the input coupler. The inspection results are compared to measurements at the partner labs prior to shipping and the nominal values in order to verify that the cryomodules have not been damaged during the transport and are ready for installation. We present an overview and analysis of the inspections for the cryomodules received to date.
	Poster THP059 [1.223 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP059
About •	paper received ※ 02 July 2019 paper accepted ※ 02 July 2019 issue date ※ 14 August 2019
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THP061	Performance of FRIB Production Quarter-Wave and Half-Wave Resonators in Dewar Certification Tests	cavity, cryomodule, SRF, MMI	1023
	W. Hartung, W. Chang, S.H. Kim, D. Norton, J.T. Popielarski, K. Saito, J.F. Schwartz, T. Xu, C. Zhang FRIB, East Lansing, Michigan, USA
	The Facility for Rare Isotope Beams (FRIB) is under construction at Michigan State University (MSU). The FRIB superconducting driver linac will accelerate ion beams to 200 MeV per nucleon. The driver linac requires 10⁴ quarter-wave resonators (QWRs, β = 0.041 and 0.085) and 220 half-wave resonators (HWRs, β = 0.29 and 0.54). The jacketed resonators are Dewar tested at MSU before installation into cryomodules. The cryomodules for β = 0.041, 0.085, and 0.29 have been completed and certified; 88% of the β = 0.54 HWRs have been certified (as of March 2019). Beam commissioning of the QWR cryomodules is in progress. The Dewar certification tests have provided valuable statistics on the performance of production QWRs and HWRs at 4.3 K and 2 K and on performance limits. Results will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP061
About •	paper received ※ 12 July 2019 paper accepted ※ 13 August 2019 issue date ※ 14 August 2019
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THP063	Inivestigation of the Possibility of High Efficiency L-Band SRF Cavity for Medium-Beta Heavy Ion Multi-Charge-State Beams	cavity, emittance, cryomodule, heavy-ion	1035
	S.M. Shanab, K. Saito, Y. Yamazaki FRIB, East Lansing, Michigan, USA
	Funding: This work was supported in part by the U.S. National Science Foundation, under Grant PHY-1102511 and by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661. The possibility of L-band SRF elliptical cavity in order to accelerate heavy ion multi-charge-state beams is being investigated for accelerating energy higher than 200 MeV/u. A first simple analytic study was performed and the result showed that the longitudinal acceptance of 1288 MHz is sufficient for heavy-ion multi-charge-state (5 charge states) medium-beta linac. Encouraged this result, detail beam dynamic simulation took place. The cryogenic heat load is also calculated for this linac with taken into consideration cavity doping technology. In this paper, a summary of the beam dynamics and cryogen-ic heat load calculations for 1288 MHz linac for heavy-ion multi-charge-state (5 charge states) medium-beta beams.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP063
About •	paper received ※ 24 June 2019 paper accepted ※ 14 August 2019 issue date ※ 14 August 2019
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THP072	Development of HOM Absorbers for CW Superconducting Cavities in Energy Recovery Linac	HOM, cavity, superconducting-cavity, SRF	1060
	T. Ota, S. Nakamura, K. Sato, M. Takasaki Toshiba Energy Systems & Solutions Corporation, Keihin Product Operations, Yokohama, Japan E. Kako, T. Konomi, H. Sakai, K. Umemori KEK, Ibaraki, Japan A. Miyamoto Toshiba, Yokohama, Japan
	Higher Order Modes (HOM) absorbers for superconducting cavities have been developing at TOSHIBA in collaboration with High Energy Accelerator Research Organization (KEK) since 2015. A new prototype HOM absorber for 1.3 GHz 9-cell superconducting cavity was fabricated. An AlN lossy dielectrics cylinder was brazed with a thin copper plate, and the cool-down tests by nitrogen gas was carried out. The copper plate and a copper cylinder were joined by electron beam welding. SUS flanges were electron beam welded to both ends of the copper cylinder to fabricate a whole prototype HOM absorber. Fabrication process of the prototype HOM absorber will be presented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP072
About •	paper received ※ 21 June 2019 paper accepted ※ 03 July 2019 issue date ※ 14 August 2019
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THP074	Microphonics Noise Suppression with Observer Based Feedback	cavity, controls, SRF, resonance	1068
	M. Keikha, K. Fong TRIUMF, Vancouver, Canada M. Moallem SFU, Surrey, Canada
	Funding: TRIUMF Detuning of superconducting radio frequency (SRF) cavities is mainly caused by the Lorentz force, which is the radiation pressure induced by a high radio frequency (RF) field, and environmental mechanical vibrations that induce undesirable interference signals referred to as microphonics. Both of these influences can be described by a second order differential equation of the mechanical vibration modes of the cavity. In this paper we consider three dominant mechanical modes of the system and develop a control scheme based on input-output linearization. It is shown through simulation studies that the proposed control technique can successfully the suppress microphonic noise due to the SRF cavity¿s dynamics.
	Poster THP074 [0.610 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP074
About •	paper received ※ 22 June 2019 paper accepted ※ 01 July 2019 issue date ※ 14 August 2019
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THP089	Development of Superconducting RF Double Spoke Cavity at IHEP	cavity, coupling, SRF, niobium	1114
	Q. Zhou, F.S. He, W.M. Pan IHEP, Beijing, People’s Republic of China
	The China Spallation Neutron Source (CSNS) is de-signed to produce spallation neutrons. CSNS upgrade is planned to increase beam power by inserting a SRF linac after drift tube linac (DTL). IHEP is developing a 325MHz double spoke cavity at ¿0 of 0.5 for the CSNS SRF linac. The cavity shape was optimized to minimize Ep/Ea while keeping Bp/Ep reasonably low. Meanwhile, mechanical design was applied to check stress, Lorentz force detuning and microphonic effects, and to minimize pressure sensitivity. A new RF coupling scheme was pro-posed to avoid electrons hitting directly on ceramic win-dow. After fabrication and post processing of cavity, the cavity reached Bp of 120mT at E_acc = 13.8MV/m and Q₀ = 1.72·10¹⁰ under vertical test at 2K.
	Poster THP089 [2.176 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP089
About •	paper received ※ 22 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019
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THP090	Characterization of SSR1 Cavities for PIP-II Linac	cavity, radiation, cryomodule, multipactoring	1120
	A.I. Sukhanov, F.G. Garcia, B.M. Hanna, S. Kazakov, Y.M. Pischalnikov, O.V. Prokofiev, W. Schappert, I. Terechkine, V.P. Yakovlev, J.C. Yun Fermilab, Batavia, Illinois, USA C. Contreras-Martinez FRIB, East Lansing, Michigan, USA S. Samani Queen Mary University of London, London, United Kingdom
	A cryomodule of 325 MHz Single Spoke Resonator type 1 (SSR1) superconducting RF cavities is being built at Fermilab for the PIP-II project. Twelve SSR1 cavities were manufactured in industry in USA (10 cavities) and India (2 cavities) and delivered to Fermilab. In this paper we present results of characterization of fully integrated jacketed cavities with high power coupler and tuner at the Fermilab Spoke Test Cryostat (STC).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP090
About •	paper received ※ 23 June 2019 paper accepted ※ 01 July 2019 issue date ※ 14 August 2019
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THP092	Status of Cryomodule Testing at CMTB for CW R&D	cavity, cryomodule, FEL, operation	1129
	J. Branlard, V. Ayvazyan, A. Bellandi, J. Eschke, C. Gümüş, D. Kostin, K.P. Przygoda, H. Schlarb, J.K. Sekutowicz DESY, Hamburg, Germany
	Cryo Module Test Bench (CMTB) is a facility to perform tests on European XFEL like superconducting accelerating modules. The 120 kW Inductive Output Tube (IOT) installed in the facility allows driving the eight superconducting cavities inside the module under test in a vector-sum or single cavity control fashion with average Continuous Wave (CW) gradients higher than 20 MV/m. The scope of these tests is to evaluate the feasibility of upgrading European XFEL to CW operation mode. Following the successful tests done on a prototype module XM-3 the initial performance results on the production module XM50 will be presented in this paper. Because of European XFEL requirements, XM50 is equipped with modified couplers that allow a variable Loaded Quality factor(QL) to values higher than 4x10⁷. A cost relevant open question is the maximum QL that can be reached while maintaining the system within the European XFEL field stability specifications of 0.01 % in amplitude and 0.01 deg in phase. Because of this, the LLRF system capability of rejecting microphonic and RF disturbances, as well as Lorentz Force Detuning (LFD) related effects in open and closed loop is of prime interest.
	Poster THP092 [1.514 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP092
About •	paper received ※ 25 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019
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THP096	ESS Prototype Cavities Developed at CEA Saclay	cavity, SRF, niobium, HOM	1143
	E. Cenni CEA-IRFU, Gif-sur-Yvette, France M. Baudrier, P. Carbonnier, G. Devanz, X. Hanus, L. Maurice, J. Plouin, D. Roudier, P. Sahuquet CEA-DRF-IRFU, 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 up to the final energy at 2 GeV. 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. CEA Saclay is in charge of the cavity prototypes that is designing, manufacturing, testing and integrating them into demonstrator cryomodules. We have manufactured 6 medium beta and 5 high beta cavities and we present here the latest results concerning these activities.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP096
About •	paper received ※ 22 June 2019 paper accepted ※ 02 July 2019 issue date ※ 14 August 2019
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THP103	Reconstruction of the Longitudinal Phase Space for the Superconducting CW HELIAC	heavy-ion, cavity, emittance, proton	1173
	S. Lauber, K. Aulenbacher, W.A. Barth, C. Burandt, F.D. Dziuba, V. Gettmann, T. Kürzeder, J. List, M. Miski-Oglu HIM, Mainz, Germany K. Aulenbacher, W.A. Barth, C. Burandt, F.D. Dziuba, P. Forck, V. Gettmann, M. Heilmann, T. Kürzeder, S. Lauber, J. List, M. Miski-Oglu, T. Sieber, S. Yaramyshev GSI, Darmstadt, Germany K. Aulenbacher, F.D. Dziuba, S. Lauber IKP, Mainz, Germany H. Podlech, M. Schwarz IAP, Frankfurt am Main, Germany
	The superconducting (SC) heavy ion HElmholtz LInear ACcelerator (HELIAC) is under development at GSI in Darmstadt in cooperation with Helmholtz Institute Mainz (HIM) and Goethe-University Frankfurt (GUF). A novel design is used for the accelerating cavities, namely SC continuous wave (CW) multigap Crossbar H-Mode cavities. For this a dedicated beam dynamics layout - the EQUidistant mUltigap Structure (EQUUS) - has been carried out a couple of years ago and is under further development. In December 2018 the GSI High Charge State Injector (HLI) delivered heavy ion beam to the already commissioned first of series superconducting RF cavity. Proper 6D-matching to the CH cavity demands sufficient beam characterisation. Slit-grid emittance measurements provided for the transverse phase space determination. By measuring the longitudinal projection of the bunch with a Feschenko Monitor (Beam Shape Monitor), the bunch profile was obtained. With a dedicated algorithm, the full longitudinal phase space at the HLI-exit could be reconstructed from a set of BSM measurements. The basic reconstruction method, all relevant BSM measurements and the resulting phase space reconstruction will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP103
About •	paper received ※ 19 June 2019 paper accepted ※ 29 June 2019 issue date ※ 14 August 2019
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THP104	Numerical Estimation of Beam Break-Up Instability in TESLA Cavities	dipole, cavity, solenoid, focusing	1178
	V. Volkov, V.M. Petrov BINP SB RAS, Novosibirsk, Russia
	In this article the numerically estimated BBU instability behaviors of a 9 cell superconducting TESLA cavity are presented for first two pass-band trapped dipole modes (18 in all). The given BBU threshold current values are calculated by the method of beam energy gain averaging on phases of dipole mode fields. BBU instability behaviors in cases of applying the cavities in Linacs as well in Energy Recovery Linacs (ERLs) are considered. The BBU influence on beam emittance degradation is demonstrated. Examples for suppression of beam BBU oscillations by a solenoid focusing and applying of an external RF generator with a feedback are visualized.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP104
About •	paper received ※ 23 June 2019 paper accepted ※ 02 July 2019 issue date ※ 14 August 2019
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FRCAA3	Industrial Cavity Production: Lessons Learned to Push the Boundaries of Nitrogen-Doping	cavity, niobium, cryomodule, SRF	1199
	D. Gonnella, S. Aderhold, A. Burrill, M.C. Ross SLAC, Menlo Park, California, USA E. Daly, G.K. Davis, F. Marhauser, A.D. Palczewski, K.M. Wilson JLab, Newport News, Virginia, USA A. Grassellino, C.J. Grimm, T.N. Khabiboulline, O.S. Melnychuk, S. Posen, D.A. Sergatskov Fermilab, Batavia, Illinois, USA
	Funding: Work supported by US DOE Contract DE-AC02-76SF00515. Nitrogen doping has been proven now in several labs to enhance Q₀ values of 1.3 GHz cavities in the gradient domain favored by CW operation. The choice of doping for the LCLS-II project has given the community a wealth of statistics and experience on the challenge of transferring the doping technology to industry. Overall, industry-produced nitrogen-doped cavities have shown excellent performance, however some technical issues have arisen. This talk focuses on lessons learned from the production of over 300 nitrogen-doped cavities for LCLS-II and how issues were mitigated to further improve performance. Finally, I will discuss pushing the boundaries of nitrogen-doping further by exploring different doping regimes in order to maintain excellent Q₀ performance, while reaching higher quench fields.
	Slides FRCAA3 [16.880 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-FRCAA3
About •	paper received ※ 02 July 2019 paper accepted ※ 03 July 2019 issue date ※ 14 August 2019
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FRCAA4	Progress in SRF CH-Cavities for the HELIAC CW Linac at GSI	cavity, heavy-ion, cryomodule, MMI	1206
	M. Miski-Oglu, K. Aulenbacher, W.A. Barth, C. Burandt, F.D. Dziuba, V. Gettmann, T. Kürzeder, S. Lauber, J. List, S. Yaramyshev HIM, Mainz, Germany K. Aulenbacher, W.A. Barth, C. Burandt, F.D. Dziuba, V. Gettmann, M. Heilmann, T. Kürzeder, S. Lauber, J. List, A. Rubin, A. Schnase, S. Yaramyshev GSI, Darmstadt, Germany K. Aulenbacher, F.D. Dziuba, J. List KPH, Mainz, Germany M. Basten, M. Busch, T. Conrad, H. Podlech, M. Schwarz IAP, Frankfurt am Main, Germany S. Lauber IKP, Mainz, Germany
	The machine beam commissioning is a major milestone of the R&D for the superconducting heavy ion continuous wave linear accelerator HELIAC of Helmholtz Institute Mainz (HIM) and GSI developed in collaboration with IAP Goethe-University Frankfurt. During successful beam commissioning of the superconducting 15-gap Crossbar H-mode cavity at GSI Helmholtzzentrum für Schwerionenforschung heavy ions up to the design beam energy have been accelerated. The design acceleration gain of 3.5 MeV has been reached with full transmission for heavy ion beams of up to 1.5 particle mueA. We present fabrication experience and results of off-line and on-line cavity performance. The next step is the procurement and commissioning of so called ’Advanced Demonstrator’ - the first of series cryomodule for the entire accelerator HELIAC. Results of further Demonstrator beam tests, as well as the status of the Advanced demonstrator project will be reported.
	Slides FRCAA4 [9.864 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-FRCAA4
About •	paper received ※ 23 June 2019 paper accepted ※ 02 July 2019 issue date ※ 14 August 2019
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FRCAB3	The Design of an Automated High-Pressure Rinsing System for SRF Cavity and the Outlook for Future Automated Cleanroom on Strings Assembly	cavity, controls, SRF, alignment	1216
	H. Guo, Q.W. Chu, Y. He, C.L. Li, Y.K. Song, T. Tan, Z.M. You IMP/CAS, Lanzhou, People’s Republic of China
	High-pressure rinsing (HPR) and cavity assembly are two critical steps in cavity post-processing. Traditionally, high-pressure rinsing processing is based on ultra pure water system, pump, rinsing wand and simple-functional control system; cavity assembly processing is based on simple fixtures, wrenches, bolts and nuts. Beside the equipments, at least two operators are required in either of these two processing. Operators and their actions could bring mistakes and cause extra airborne particle contamination in cleanroom. To avoid the risk from labors, a robot has been introduced in IMP cleanroom for HPR assisting and assembly assisting. Labor cost and cavity RF test results are compared between the circumstances with and without robot assisting. In this work, an automated HPR system that has been designed and will be installed in IMP cleanroom will be presented. In addition, a future automated cleanroom on strings assembly will be discussed as well.
	Slides FRCAB3 [6.203 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-FRCAB3
About •	paper received ※ 03 July 2019 paper accepted ※ 12 July 2019 issue date ※ 14 August 2019
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Paper

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MOFAA1

LCLS-II: Status, Issues and Plans

cavity, SRF, cryomodule, FEL

1

M.C. Ross
SLAC, Menlo Park, California, USA

Funding: Work supported by Department of Energy contract DE-AC02-76SF00515
The Linac Coherent Light Source II (LCLS-II) project requires the assembly, test, and installation of 37 cryomodules (CM) in order to deliver a 4 GeV CW electron beam to the FEL undulators for production of both hard and soft X-ray pulses at a repetition rate of up to 1 MHz. SRF cavity performance in the 30+ tested CM exceeds gradient and cryogenic dynamic heat-load requirements (set at 16 MV/m and 10 W resp). In this talk we present microphonics, shipping, magnetic-flux exclusion, and field emission performance. The US funding agency, DOE, has recently approved an additional 20 CM for the extension of LCLS-II to 8 GeV. This paper will also include initial cavity and heat-load performance results for the extension project, LCLS-II-HE.

Slides MOFAA1 [30.146 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOFAA1

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paper received ※ 25 June 2019 paper accepted ※ 04 July 2019 issue date ※ 14 August 2019

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MOFAA3

The FRIB SC-Linac - Installation and Phased Commissioning

cryomodule, MMI, cavity, cryogenics

12

J. Wei, H. Ao, S. Beher, B. Bird, N.K. Bultman, F. Casagrande, D. Chabot, W. Chang, S. Cogan, C. Compton, J. Curtin, K.D. Davidson, E. Daykin, K. Elliott, A. Facco, A. Fila, V. Ganni, A. Ganshyn, P.E. Gibson, T. Glasmacher, I. Grender, W. Hartung, L. Hodges, K. Holland, H.-C. Hseuh, A. Hussain, M. Ikegami, S. Jones, T. Kanemura, S.H. Kim, P. Knudsen, M.G. Konrad, J. LeTourneau, Z. Li, S.M. Lidia, G. Machicoane, P. Manwiller, F. Marti, T. Maruta, E.S. Metzgar, S.J. Miller, D.G. Morris, C. Nguyen, K. Openlander, P.N. Ostroumov, A.S. Plastun, J.T. Popielarski, L. Popielarski, J. Priller, M.A. Reaume, H.T. Ren, T. Russo, K. Saito, M. Shuptar, J.W. Stetson, D.R. Victory, R. Walker, X. Wang, J.D. Wenstrom, M. Wright, M. Xu, T. Xu, Y. Yamazaki, Q. Zhao, S. Zhao
FRIB, East Lansing, Michigan, USA
K. Dixon, M. Wiseman
JLab, Newport News, Virginia, USA
A. Facco
INFN/LNL, Legnaro (PD), Italy
K. Hosoyama
KEK, Ibaraki, Japan
M.P. Kelly
ANL, Lemont, Illinois, USA
R.E. Laxdal
TRIUMF, Vancouver, Canada

Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661.
The Facility for Rare Isotope Beams (FRIB) superconducting (SC) driver linac is designed to accelerate all stable ions including uranium to energies above 200 MeV/u primarily with 46 cryomodules containing 324 quarter-wave resonators (QWR) and half-wave (HWR) resonators. With the newly commissioned helium refrigeration system supplying liquid helium to the QWR and solenoids, heavy ion beams including Ne, Ar, Kr and Xe were accelerated to the charge stripper location above 20 MeV/u with the first linac segment consisting of 15 cryomodules containing 10⁴ QWRs of β=0.041 and 0.085 and 39 solenoids. Installation of cryomodules with β=0.29 and 0.53 HWRs is proceeding in parallel. Development of β=0.65 elliptical resonators is on-going supporting the FRIB energy upgrade to 400 MeV/u. This paper summarizes the SC-linac installation and phased commissioning status that is on schedule and on budget to the FRIB project.

Slides MOFAA3 [46.571 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOFAA3

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paper received ※ 23 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019

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MOP005

The Facility for Rare Isotope Beams Superconducting Cavity Production Status and Findings Concerning Surface Defects

cavity, SRF, niobium, status

31

C. Compton
NSCL, East Lansing, Michigan, USA
H. Ao, J. Asciutto, K. Elliott, W. Hartung, S.H. Kim, E.S. Metzgar, S.J. Miller, J.T. Popielarski, L. Popielarski, K. Saito, T. Xu
FRIB, East Lansing, Michigan, USA
J. Craft
SLAC, Menlo Park, California, 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), located on the campus of Michigan State University (MSU) will require 324 Superconducting Radio Frequency (SRF) cavities in the driver linac. Four types of cavities of two classes, quarter-wave (β=0.041 and 0.085) and half-wave (β=0.29 and 0.53), will be housed in 46 cryomodules. To date, FRIB has tested over 300 cavities in vertical Dewar tests as part of the certification procedures. Incoming cavities, fabricated in industry, are sequenced through acceptance inspection and checked for non-conformance. If accepted, the cavities are processed, assembled onto a vertical test stand, and cold tested. A large database of cavity surface images has been collected with the aid of a borescope camera. Borescope inspection is a standard step that is performed at incoming inspection, post-acid bulk etch, and after failed tests (if necessary) for each cavity, in order to locate any non-conformances. Findings of surface defects relating to degraded cavity performance will be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP005

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paper received ※ 02 July 2019 paper accepted ※ 13 August 2019 issue date ※ 14 August 2019

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MOP019

Surface Preparation and Optimization of SC CH Cavities

cavity, operation, coupling, ECR

71

P. Müller, M. Basten, M. Busch, T. Conrad, H. Podlech
IAP, Frankfurt am Main, Germany
K. Aulenbacher, F.D. Dziuba, M. Miski-Oglu
HIM, Mainz, Germany
W.A. Barth
GSI, Darmstadt, Germany

The Institute of Applied Physics (IAP) introduced the superconducting multi-gap CH-structure, which is mainly designed for low beta hadron acceleration. In 2017, a 217 MHz sc CH-structure was successfully tested with beam at GSI and multiple CH-structures are currently under development for the GSI cw linac. RF performance of all sc cavities are limited by the surface properties of the used material. Therefore, sufficient surface preparation and optimization is necessary to achieve optimal performance. Presently as standard procedure BCP and HPR is used for CH-cavities. Several surface treatments will be applied to the very first CH-prototype, a 360 MHz, 19-cell cavity. Prior to the first treatment, the status of the cavity was examined, including leak tests and performance tests at 4 and 2 K. This paper presents the performance development of a sc CH cavity depending on different preparation methods.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP019

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paper received ※ 23 June 2019 paper accepted ※ 05 July 2019 issue date ※ 14 August 2019

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MOP022

Superconducting RF Cavity Materials Research at the S-DALINAC

cavity, niobium, SRF, simulation

74

R. Grewe, L. Alff, M. Arnold, J. Conrad, S. Flege, M. Major, N. Pietralla
TU Darmstadt, Darmstadt, Germany
F. Hug
IKP, Mainz, Germany

Funding: Supported by BMBF Through 05H18RDRB2
Current state-of-the-art superconducting rf (srf) accelerators are mostly using cavities made of high RRR bulk niobium (Nb). The maximum field gradients and quality factors (Q₀) of these cavities are basically reached now. To further increase the srf cavity properties for future accelerator facilities, research of new materials for srf cavity applications is necessary. The current research at the S-DALINAC* is focused on the development of bake-out procedures of Nb samples and cavities in nitrogen (N) atmosphere of up to 100 mbar to nucleate the delta-phase (d-phase) of the Nb-N binary system. The d-phase has superconducting properties which exceed the properties of bulk Nb. This makes the d-phase attractive for srf applications. The vertical test cryostat (vt) at the S-DALINAC has been upgraded and recommissioned to allow investigations of the quality factor and accelerating field gradients of cavities before and after bake-out. The vt upgrade includes a newly developed variable input coupling to allow matching of the external q-factor (Qex) to Q₀. The results of the ongoing research of the nitrogen atmosphere bake-out procedures and the upgrade of the vt will be presented.
*N. Pietralla, Nuclear Physics News, Vol. 28, No. 2, 4 (2018)

Poster MOP022 [1.759 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP022

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paper received ※ 21 June 2019 paper accepted ※ 01 July 2019 issue date ※ 14 August 2019

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MOP033

The Beam Dynamics Updates of the Fermilab PIP-II 800 MeV Superconducting Linac

SRF, cavity, optics, emittance

123

A. Saini, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA
E. Pozdeyev
FRIB, East Lansing, Michigan, USA

The Proton Improvement Plan (PIP) -II is a high intensity proton facility being developed to support a neutrino program over the next two decades at Fermilab. At its core is the design and construction of a Continuous Wave compatible superconducting radio frequency linear accelerator that would accelerate an average beam current of 2 mA up to 800 MeV. This paper presents recent updates in the beam dynamics leading to a reliable and robust linac design and simplifying the cryo-module assembly.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP033

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paper received ※ 23 June 2019 paper accepted ※ 01 July 2019 issue date ※ 14 August 2019

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MOP034

European XFEL: Accelerating Module Repair at DESY

cavity, FEL, SRF, operation

127

D. Kostin, J. Eschke, K. Jensch, N. Krupka, D. Reschke, S. Saegebarth, J. Schaffran, M. Schalwat, P. Schilling, M. Schmökel, S. Sievers, N. Steinhau-Kühl, E. Vogel, H. Weise, M. Wiencek, B. van der Horst
DESY, Hamburg, Germany

The European XFEL is in operation since 2017. The design projected energy of 17.5 GeV was reached, even with the last 4 main linac accelerating modules not yet installed. 2 out of 4 not installed modules did suffer from strong cavity performance degradation, namely increased field emission, and required surface processing. The first of two modules is reassembled and tested. The module test results confirm a successful repair action. The module repair and test steps are described together with cavities performance evolution.

Poster MOP034 [1.863 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP034

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paper received ※ 17 June 2019 paper accepted ※ 29 June 2019 issue date ※ 14 August 2019

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MOP036

Microphonics Suppression Study in ARIEL e-Linac Cryomodules

cavity, cryomodule, GUI, pick-up

136

Y. Ma, K. Fong, J.J. Keir, D. Kishi, S.R. Koscielniak, D. Lang, R.E. Laxdal, S.L. Liu, R.S. Sekhon, X. Wang
TRIUMF, Vancouver, Canada

Now the stage of the 30 MeV portion of ARIEL (The Advanced Rare Isotope Laboratory) e-Linac (1.3 GHz, SRF) is under commissioning which includes an injector cryomodule (ICM) with a single nine-cell cavity and the 1st accelerator cryomodule (ACM1) with two cavities configuration. The two ACM1 cavities are driven by a single klystron with vector-sum control and running in CW mode. We have observed a ponderomotive instability in ACM1 driven by the Lorentz force and seeded through microphonics that impacts beam stability [1-5]. Extensive damping has been implemented during a recent shut-down. The beam test results show 20 MeV acceleration gain can be reached by ACM1. A fast piezoelectric (Pie-zo) tuner is under development to allow a fast tuning compensation for the e-Linac cavities. In this paper, the progress of the microphonics suppression of Cryomod-ules is presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP036

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paper received ※ 24 June 2019 paper accepted ※ 01 July 2019 issue date ※ 14 August 2019

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MOP045

The LCLS-II HE High Q and Gradient R&D Program

cavity, SRF, cryomodule, niobium

154

D. Gonnella, S. Aderhold, A. Burrill, G.R. Hays, T.O. Raubenheimer, M.C. Ross
SLAC, Menlo Park, California, USA
D. Bafia, M. Checchin, A. Grassellino, M. Martinello, A.S. Romanenko
Fermilab, Batavia, Illinois, USA
M. Ge, M. Liepe, S. Posen
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
A.D. Palczewski, C.E. Reece
JLab, Newport News, Virginia, USA

Funding: US DOE and the LCLS-II HE Project
The LCLS-II HE project is a high energy upgrade to the superconducting LCLS-II linac. It consists of adding twenty additional 1.3 GHz cryomodules to the linac, with cavities operating at a gradient of 20.8 MV/m with a Q₀ of 2.7·10¹⁰. Performance of LCLS-II cryomodules has suggested that operations at this high of a gradient will not be achievable with the existing cavity recipe employed. Therefore a research program was developed between SLAC, Fermilab, Thomas Jefferson National Accelerator Facility, and Cornell University in order to improve the cavity processing method of the SRF cavities and reach the HE goals. This program explores the doping regime beyond what was done for LCLS-II and also has looked to further developed nitrogen-infusion. Here we will summarize the results from this R\&D program, showing significant improvement on both single-cell and 9-cell cavities compared with the original LCLS-II cavity recipe.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP045

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paper received ※ 25 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019

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MOP050

Modular Power Couplers for 217 MHz Superconducting CH-Cavities

cavity, Windows, heavy-ion, simulation

168

J. List, K. Aulenbacher, W.A. Barth, C. Burandt, F.D. Dziuba, V. Gettmann, T. Kürzeder, S. Lauber, M. Miski-Oglu
HIM, Mainz, Germany
K. Aulenbacher, W.A. Barth, C. Burandt, V. Gettmann, M. Heilmann, T. Kürzeder, S. Lauber, J. List, M. Miski-Oglu, A. Schnase, S. Yaramyshev
GSI, Darmstadt, Germany
K. Aulenbacher, F.D. Dziuba, S. Lauber, J. List
IKP, Mainz, Germany
M. Basten, M. Busch, H. Podlech, M. Schwarz
IAP, Frankfurt am Main, Germany

The HELmholtz LInear ACcelerator (HELIAC) is being developed by a collaboration of HIM, GSI and the Goethe University of Frankfurt. It is a superconducting (sc), continuous wave (cw) heavy ion linac that comprises novel Crossbar H-mode (CH) cavities. In April 2017 and November/December 2018 the first sc CH-cavity of the linac was tested with beam. The first operations of the cavity showed, that the prototype of the rf power coupler needs to be further improved. A new version of the coupler is being designed at the HIM. Further development will mainly be focused on the heat input into the cryostat caused by the coupler. Also the coupler will have a modular design. This improves the accessibility and maintenance of the coupler. Various cryogenic and rf tests are foreseen, to provide a reliable, fail-safe coupler for the HELIAC. For an enhanced coupler test stand a movable reflector has been designed and built. With its movable semi-reflective element, it allows to operate the test stand in a resonance mode. In addition, the movable reflector can vary the coupling factor. This contribution discusses the recent coupler R&D for the HELIAC.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP050

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paper received ※ 21 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019

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MOP051

3.9 GHz SRF Production Cavities for LCLS-II

cavity, cryomodule, radiation, vacuum

173

S. Aderhold, A. Burrill
SLAC, Menlo Park, California, USA
D.J. Bice, C.M. Ginsburg, C.J. Grimm, T.N. Khabiboulline, O.S. Melnychuk, D.A. Sergatskov, N. Solyak, G. Wu
Fermilab, Batavia, Illinois, USA

Funding: This work was supported by the US DOE and the LCLS-II Project.
The main part of the SRF linac for the Linac Coherent Light Source II (LCLS-II) at SLAC will consist of 35 cryomodules with superconducting RF cavities operating at 1.3 GHz. In addition, two cryomodules with 3.9 GHz cavities will be installed and help to linearize the longitudinal phase space of the beam. During the design verification phase, four prototype 9-cell 3.9 GHz cavities had been built by industry and then processed, including chemical surface removal and heat treatment, and tested at Fermi National Accelerator Laboratory. Based on the resulting cavity treatment recipe, 24 cavities (for two cryomodules to be installed in the linac and one spare cryomodule) have been built by industry and tested at Fermilab prior to cryomodule string assembly. We present an overview of the cavity production and the results of the vertical acceptance tests for the LCLS-II 3.9 GHz cavities.

Poster MOP051 [1.015 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP051

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paper received ※ 02 July 2019 paper accepted ※ 03 July 2019 issue date ※ 14 August 2019

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MOP054

Fabrication of 3.0-GHz Single-cell Cavities for Thin-film Study

cavity, SRF, MMI, FEL

177

T. Saeki, H. Hayano, H. Inoue, R. Katayama, T. Kubo
KEK, Ibaraki, Japan
F.E. Hannon, R.A. Rimmer, A-M. Valente-Feliciano
JLab, Newport News, Virginia, USA
H. Ito
Sokendai, Ibaraki, Japan
Y. Iwashita, H. Tongu
Kyoto ICR, Uji, Kyoto, Japan

Funding: This work is supported by JSPS KAKENHI JP17H04839, JSPS KAKENHI JP26600142, Japan-US Research Collaboration Program, and the Collaborative Research Program of ICR Kyoto Univ. (2018-13).
We fabricated 3.0-GHz single-cell cavities with Cu and Nb materials for testing thin-film creations on the inner surface of the cavities in collaboration between Jefferson Laboratory (JLab) and KEK. The cavity was designed at JLab. According to the design of cavity, the press-forming dies and trimming fixtures for the cavity-cell were also designed and fabricated at JLab. These dies and trimming fixtures were transported to KEK, and the rest of fabrication processes were done at KEK. Finally nine Cu 3.0-GHz single-cell cavities and six Nb 3.0-GHz single-cell cavities were fabricated. Two Cu 3.0-GHz single-cell cavities were mechanically polished at Jlab. All of these cavities will be utilized for the tests of various thin-film creations at JLab and KEK. This presentation describes details of the fabrication of these cavities.

Poster MOP054 [1.203 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP054

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paper received ※ 05 July 2019 paper accepted ※ 13 August 2019 issue date ※ 14 August 2019

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MOP055

Fabrication and Performance of Superconducting Quarter-Wavelength Resonators for SRILAC

cavity, operation, cryomodule, acceleration

182

K. Suda, O. Kamigaito, K. Ozeki, N. Sakamoto, Y. Watanabe, K. Yamada
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

A new superconducting booster linac (SRILAC) at the RIKEN heavy-ion linac is under construction. Ten 73-MHz low-beta quarter-wavelength resonators (QWRs) that operate at 4 K have been fabricated from pure niobium sheets. The cavity parts were assembled by electron beam welding. The resonant frequency for each cavity was adjusted by changing the lengths of the straight sections before welding. The performance and frequency were evaluated by vertical tests. All the cavities exceeded the design specifications of Q₀ = 1x10⁹ and E_acc = 6.8 MV/m. Details of the fabrication and frequency tuning as well as the performance of the cavities are reported.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP055

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paper received ※ 17 July 2019 paper accepted ※ 13 August 2019 issue date ※ 14 August 2019

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MOP057

Electropolishing of PIP-II Low Beta Cavity Prototypes

cavity, cathode, experiment, FEL

194

M. Bertucci, A. Bosotti, A. D’Ambros, P. Michelato, L. Monaco, C. Pagani, R. Paparella, D. Sertore
INFN/LASA, Segrate (MI), Italy
A. Gresele, A. Visentin
Ettore Zanon S.p.A., Nuclear Division, Schio, Italy
C. Pagani
Università degli Studi di Milano & INFN, Segrate, Italy
D. Rizzetto, M. Rizzi
Ettore Zanon S.p.A., Schio, Italy

We present the upgrade of the EP facility for the surface treatment of PIP-II low beta cavities. The main process parameters, such as voltage, treatment time, acid throughput and cathode geometry, already optimized on the previous experience of 1.3 GHz Tesla-shape cavities, are discussed taking into account the different cavity size and geometry. The first surface treatments have been performed at Ettore Zanon SpA on single cell cavity prototypes in order to reach good final surface finishing and the required thickness removal. In the meantime, the upgrade of the system for the treatment of multicell PIP-II prototype cavities is presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP057

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paper received ※ 23 June 2019 paper accepted ※ 02 July 2019 issue date ※ 14 August 2019

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MOP060

INFN-LASA for the PIP-II Project

cavity, niobium, SRF, interface

205

R. Paparella, M. Bertucci, A. Bignami, A. Bosotti, M. Chiodini, A. D’Ambros, P. Michelato, L. Monaco, D. Sertore
INFN/LASA, Segrate (MI), Italy
J.F. Chen
SARI-CAS, Pudong, Shanghai, People’s Republic of China
C. Pagani
Università degli Studi di Milano & INFN, Segrate, Italy
L. Sagliano
ESS, Lund, Sweden

INFN-LASA joined the international effort for the PIP-II project in Fermilab to build the 650 MHz superconducting cavities realizing the low-beta section of the 800 MeV proton linac. After developing the electro-magnetic and mechanical design, INFN-Milano started the prototyping phase by producing five single-cells and two complete 5-cells cavities. This paper reports the status of PIP-II activities at INFN-LASA summarizing manufacturing experience and preliminary experimental results.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP060

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paper received ※ 24 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019

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MOP065

Upgrade of the S-DALINAC Injector Capture Section

cavity, MMI, gun, target

227

S. Weih, M. Arnold, J. Enders, N. Pietralla
TU Darmstadt, Darmstadt, Germany
D.B. Bazyl, H. De Gersem, W.F.O. Müller
TEMF, TU Darmstadt, Darmstadt, Germany

Funding: Work supported by DFG through GRK 2128 "AccelencE"
The superconducting injector section of the S-DALINAC (superconducting Darmstadt linear electron accelerator) [1] constists of two cryomodules with three 3-GHz SRF cavities in total. The first cavity of this pre-accelerator is currently a 5-cell structure designed for relativistic particle velocities. Since the gun delivers a 250 keV beam (β=0.74), this cavity is not suited for an efficient capture of the low-energy electron bunches provided by the normal-conducting section of the injector. Beam dynamics simulations and operational experience have shown a large low-energy tail in the phase-space distribution of the bunch downstream of the injector, which arises from the large phase-slippage during the capture in the 5-cell. It is therefore intended to replace the cavity with a beta-adapted 6-cell, re-using most of the cryostat parts. This contribution presents the status of the injector upgrade and the layout and manufacturing status of the new cavity.
*N. Pietralla, Nuclear Physics News, Vol. 28, No. 2, 4 (2018)

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP065

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paper received ※ 21 June 2019 paper accepted ※ 02 July 2019 issue date ※ 14 August 2019

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MOP081

Considerations for Efficient RF Operation for the Advanced cw-Linac Demonstrator at GSI

cavity, cryomodule, heavy-ion, SRF

267

C. Burandt, K. Aulenbacher, W.A. Barth, F.D. Dziuba, V. Gettmann, T. Kürzeder, S. Lauber, J. List, M. Miski-Oglu, S. Yaramyshev
HIM, Mainz, Germany
K. Aulenbacher, W.A. Barth, C. Burandt, F.D. Dziuba, V. Gettmann, M. Heilmann, T. Kürzeder, S. Lauber, J. List, M. Miski-Oglu, A. Schnase, S. Yaramyshev
GSI, Darmstadt, Germany
K. Aulenbacher, F.D. Dziuba, S. Lauber, J. List
IKP, Mainz, Germany
M. Basten, M. Busch, H. Podlech, M. Schwarz
IAP, Frankfurt am Main, Germany

The FAIR@GSI accelerator facility will require the GSI-UNILAC to provide short heavy ion pulses of highest intensity at low repetition rate for injection into the 18 Tm synchrotron SIS18. However, successful physics programs like SHE (Super Heavy Elements) rely on the UNILAC providing for heavy ion beams of high average current and high duty factor. In the next future, a dedicated super-conducting (sc) cw-Linac should therefore deliver cw beams to the experiments associated with those programs. As a first step towards this goal, beam tests with a single sc Cross-bar H-mode (CH) cavity were successfully conducted in 2017/2018. Within the scope of an Advanced Demonstrator project, current activities now aim at a beam test of a full cryomodule with three sc CH cavities and a sc rebuncher. Given a limited amount of rf power available per cavity and the necessity to accelerate different ion species with different mass-to-charge ratios, the loaded quality factor Q of the different resonators has to be chosen very carefully. This contribution discusses the simulations performed in this context.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP081

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paper received ※ 21 June 2019 paper accepted ※ 29 June 2019 issue date ※ 14 August 2019

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MOP087

IFMIF Resonators Development and Performance

cavity, SRF, cryomodule, solenoid

293

G. Devanz, M. Baudrier, P. Carbonnier, F. Éozénou, E. Fayette, D. Roudier, P. Sahuquet, C. Servouin
CEA-DRF-IRFU, France
N. Bazin, S. Chel, L. Maurice
CEA-IRFU, Gif-sur-Yvette, France

The prototype IFMIF cryomodule encloses eight superconducting 175 MHz beta 0.09 Half-Wave Resonators (HWR). They are designed together with the power coupler to accelerate a high intensity deuteron beam (125 mA) from to 5 to 9 MeV. One prototype HWR and the 8 cavities to be hosted in the cryomodule have been manufactured, prepared and tested. The paper describes the phases of the cavities development, including fabrication, processing, and RF resonant frequency management. We focus on the results of the RF tests which have been performed for all bare and jacketed HWRs in a vertical cryostat.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP087

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paper received ※ 23 June 2019 paper accepted ※ 03 July 2019 issue date ※ 14 August 2019

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MOP097

Preliminary Design of the IFMIF-DONES Superconducting Linac

cavity, cryomodule, SRF, neutron

311

T. Plomion, N. Bazin, N. Chauvin, G. Devanz, J. Plouin, K. Romieu
CEA-DRF-IRFU, France
S. Chel
CEA-IRFU, Gif-sur-Yvette, France

The linear accelerator for the DONES facility (DEMO oriented neutron source) will serve as a neutron source for the assessment of materials damage in future fusion reactors. The DONES accelerator, which is based on the design of LIPac (Linear IFMIF Prototype Accelerator, which is under construction in Rokkasho, Japan) will accelerate deuterons from 100 keV up to 40 MeV at full CW current of 125 mA. This paper will present the preliminary design of the superconducting linac which is based on five cryomodules.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-MOP097

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paper received ※ 21 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019

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TUP002

Modeling of Superconducting Spoke Cavity with its Control Loops Systems for the MYRRHA Linac Project

cavity, LLRF, cryomodule, feedback

387

M. Dominiczak
ACS, Orsay, France
F. Bouly
LPSC, Grenoble Cedex, France
N. Gandolfo, C. Joly
Université Paris-Saclay, CNRS/IN2P3, IJCLab, 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)

Poster TUP002 [1.335 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP002

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paper received ※ 23 June 2019 paper accepted ※ 04 July 2019 issue date ※ 14 August 2019

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TUP004

Latest Cryogenic Test Results of the Superconducting β=0.069 CH-cavities for the HELIAC-project

cavity, vacuum, cryomodule, heavy-ion

392

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 TUP004 [0.958 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP004

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paper received ※ 22 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019

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TUP005

Cavity Designs for the CH3 to CH11 of the Superconducting Heavy Ion Accelerator HELIAC

cavity, heavy-ion, resonance, electron

396

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.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP005

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paper received ※ 19 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019

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TUP007

Electromagnetic Design of the Prototype Spoke Cavity for the JAEA-ADS Linac

cavity, SRF, proton, superconductivity

399

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.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP007

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paper received ※ 02 July 2019 paper accepted ※ 04 July 2019 issue date ※ 14 August 2019

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TUP013

Non-Evaporative Getter-Based Differential Pumping System for SRILAC at RIBF

vacuum, SRF, cavity, operation

419

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.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP013

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paper received ※ 03 July 2019 paper accepted ※ 14 August 2019 issue date ※ 14 August 2019

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TUP023

Experience of LCLS-II Cavities Radial Tuning at DESY

cavity, HOM, SRF, FEL

456

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 TUP023 [0.521 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP023

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paper received ※ 23 June 2019 paper accepted ※ 01 July 2019 issue date ※ 14 August 2019

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TUP028

Development of Vertical Electropolishing Facility for Nb 9-Cell Cavity (3)

cavity, scattering, cathode, controls

470

Y.I. Ida, V. Chouhan, K.N. Nii
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 TUP028 [0.444 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP028

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paper received ※ 24 June 2019 paper accepted ※ 29 June 2019 issue date ※ 14 August 2019

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TUP033

Modal Analysis of the EXFEL 1.3 GHz Cavity and Cryomodule Main Components and Comparison with Measured Data

cavity, cryomodule, FEL, vacuum

488

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.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP033

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paper received ※ 18 June 2019 paper accepted ※ 01 July 2019 issue date ※ 14 August 2019

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TUP037

Construction of Superconducting Linac Booster for Heavy-Ion Linac at RIKEN Nishina Center

cryomodule, vacuum, controls, booster

502

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.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP037

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paper received ※ 02 July 2019 paper accepted ※ 04 July 2019 issue date ※ 14 August 2019

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TUP042

Measurement of Mechanical Vibration of SRILAC Cavities

cavity, niobium, ECR, cryomodule

513

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 TUP042 [6.957 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP042

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paper received ※ 27 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019

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TUP064

Flashover on RF Window of HWR SRF Cavity

cavity, pick-up, electron, SRF

597

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.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP064

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paper received ※ 23 June 2019 paper accepted ※ 04 July 2019 issue date ※ 14 August 2019

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TUP066

New Design of SSR2 Spoke Cavity for PIP II SRF Linac

cavity, quadrupole, multipactoring, HOM

600

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.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP066

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paper received ※ 21 June 2019 paper accepted ※ 01 July 2019 issue date ※ 14 August 2019

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TUP084

Testing of the Piezo-actuators at High Dynamic Rate Operational Conditions

SRF, cavity, operation, vacuum

656

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 TUP084 [3.168 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP084

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paper received ※ 23 June 2019 paper accepted ※ 04 July 2019 issue date ※ 14 August 2019

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TUP086

Frequency Tuning System Based on Mobile Plungers For Superconductive Coaxial Half Wave Resonators

cavity, simulation, SRF, vacuum

664

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.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP086

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paper received ※ 22 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019

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TUP087

Development and Performances of Spoke Cavity Tuner for MYRRHA Linac Project

cavity, controls, simulation, operation

667

N. Gandolfo, S. Blivet, P. Duchesne, D. Le Dréan
Université Paris-Saclay, CNRS/IN2P3, IJCLab, 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 TUP087 [2.367 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP087

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paper received ※ 01 July 2019 paper accepted ※ 03 July 2019 issue date ※ 14 August 2019

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TUP089

FRIB LS1 Cryomodule’s Solenoid Commissioning

solenoid, cryomodule, MMI, controls

671

M. Xu, H. Ao, B. Bird, R. Bliton, C. Compton, J. Curtin, L. Hodges, K. Holland, S.J. Miller, K. Saito, 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.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP089

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paper received ※ 24 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019

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TUP093

Summary of FRIB Cavity Processing in the SRF Coldmass Processing Facility and Lessons Learned

cavity, niobium, SRF, controls

680

E.S. Metzgar, B.W. Barker, K. Elliott, W. Hartung, L. Popielarski, 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.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP093

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paper received ※ 22 June 2019 paper accepted ※ 29 June 2019 issue date ※ 14 August 2019

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TUP096

Optimization of Clean Room Infrastructure and Procedure During LCLS-II Cryomodule Production at Fermilab

cavity, cryomodule, vacuum, detector

695

G. Wu, S.D. Adams, T.T. Arkan, M.A. Battistoni, D.J. Bice, 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.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP096

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paper received ※ 23 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019

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TUP098

Preparation for the Advanced Demonstrator Testing at GSI

cavity, solenoid, cryomodule, heavy-ion

698

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.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP098

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paper received ※ 22 June 2019 paper accepted ※ 01 July 2019 issue date ※ 14 August 2019

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TUP101

LCLS-II Cryomodules Production Experience and Lessons Learned at Fermilab

cryomodule, vacuum, cavity, FEL

709

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 TUP101 [0.834 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP101

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paper received ※ 20 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019

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TUP106

Mechanical Tuner for a 325 MHz Balloon Single Spoke Resonator

cavity, cryomodule, simulation, operation

730

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 TUP106 [1.089 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-TUP106

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paper received ※ 23 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019

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WETEA3

Status of the IFMIF/EVEDA Superconducting Linac

cavity, SRF, solenoid, cryomodule

735

N. Bazin, G. Devanz, H. Jenhani, O. Piquet
CEA-DRF-IRFU, France
S. Chel
CEA-IRFU, Gif-sur-Yvette, France
T. Ebisawa
QST, Aomori, Japan
G. Phillips
F4E, Germany
D. Regidor, F. Toral
CIEMAT, Madrid, Spain

The IFMIF accelerator aims to provide an accelerator-based D-Li neutron source to produce high intensity high energy neutron flux to test samples as possible candidate materials to a full lifetime of fusion energy reactors. A prototype of the low energy part of the accelerator (LIPAc) is under construction at Rokkasho Fusion Institute in Japan. It includes one cryomodule containing 8 half-wave resonators (HWR) operating at 175 MHz and eight focusing solenoids. The talk will cover the progress of developments in the IFMIF/EVEDA cryomodule: the qualification of 8 cavities, the RF conditioning results of 8 high-power couplers, the manufacturing and test of the 8 superconducting solenoids and the equivalent operational equivalent tests performed at Saclay. The assembling status of the cryomodule at Rokkasho site will also be presented.

Slides WETEA3 [11.091 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-WETEA3

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paper received ※ 20 June 2019 paper accepted ※ 29 June 2019 issue date ※ 14 August 2019

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WETEB1

Development of Superconducting Quarter-Wave Resonator and Cryomodule for Low-Beta Ion Accelerators at RIKEN Radioactive Isotope Beam Factory

cavity, cryomodule, vacuum, SRF

750

N. Sakamoto, T. Dantsuka, M. Fujimaki, H. Imao, O. Kamigaito, K. Kusaka, H. Okuno, K. Ozeki, K. Suda, A. Uchiyama, T. Watanabe, Y. Watanabe, K. Yamada
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

A prototype cryomodule with a superconducting quarter- wave resonator (SC QWR) has been developed at RIKEN Radioactive Isotope Beam Factory (RIBF). During the last SRF conference, we presented the performance of our first SC QWR and the first cool-down test of its cryomodule. Since then, we have continued our efforts to improve cavity performance and succeeded in recovering deteriorated Q₀. In this paper, we report what we constructed and learned from the prototype, including design issues with the cavity and its cryomodule. Design issues related to the new SC QWRs and their cryomodules for the SC linac booster of the RIKEN Heavy-Ion Linac (RILAC) are described as well.

Slides WETEB1 [120.252 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-WETEB1

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paper received ※ 24 June 2019 paper accepted ※ 05 July 2019 issue date ※ 14 August 2019

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WETEB6

Active Suppression of Microphonics Detuning in High QL Cavities

cavity, controls, resonance, SRF

776

N. Banerjee, G.H. Hoffstaetter, M. Liepe, P. Quigley
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: This work was performed through the support of New York State Energy Research and Development Agency (NYSERDA). SRF 2019 provided travel support in the form of a student grant.
Accelerators operating with low beam loading such as Energy Recovery Linacs (ERL) greatly benefit from using SRF cavities operated at high loaded quality factors, since it leads to lower RF power requirements. However, large microphonics detuning several times the operating bandwidth of the cavities severely limit the maximum accelerating fields which can be sustained in a stable manner. In this talk, I will describe an active microphonics control technique based on the narrow band Active noise Control (ANC) algorithm which we have used in CBETA, a multi-turn SRF ERL being commissioned at Cornell University. I will describe its stability and performance during beam operations of CBETA with consistent reduction of peak detuning by almost a factor of 2 on multiple cavities.

Slides WETEB6 [10.296 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-WETEB6

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paper received ※ 23 June 2019 paper accepted ※ 29 June 2019 issue date ※ 14 August 2019

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WETEB7

A Ferroelectric Fast Reactive Tuner for Superconducting Cavities

cavity, controls, experiment, superconducting-cavity

781

N.C. Shipman, J. Bastard, M.R. Coly, F. Gerigk, A. Macpherson, N. Stapley
CERN, Geneva, Switzerland
I. Ben-Zvi
BNL, Upton, New York, USA
G. Burt, A. Castilla
Lancaster University, Lancaster, United Kingdom
C.-J. Jing, A. Kanareykin
Euclid TechLabs, LLC, Solon, Ohio, USA
S. Kazakov
Fermilab, Batavia, Illinois, USA
E. Nenasheva
Ceramics Ltd., St. Petersburg, Russia

A prototype FerroElectric Fast Reactive Tuner (FE-FRT) for superconducting cavities has been developed, which allows the frequency to be controlled by application of a potential difference across a ferroelectric residing within the tuner. This technique has now become practically feasible due to the recent development of a new extremely low loss ferroelectric material. In a world first, CERN has tested the prototype FE-FRT with a superconducting cavity, and frequency tuning has been successfully demonstrated. This is a significant first step in the development of an entirely new class of tuner. These will allow electronic control of cavity frequencies, by a device operating at room temperature, within timescales that will allow active compensation of microphonics. For many applications this could eliminate the need to use over-coupled fundamental power couplers, thus significantly reducing RF amplifier power.

Slides WETEB7 [21.570 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-WETEB7

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paper received ※ 23 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019

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THFUA2

Evaluation of the Superconducting Characteristics of Multi-Layer Thin-Film Structures of NbN and SiO₂ on Pure Nb Substrate

experiment, DTL

807

R. Katayama, H. Hayano, T. Kubo, T. Saeki
KEK, Ibaraki, Japan
C.Z. Antoine
CEA-IRFU, Gif-sur-Yvette, France
H. Ito
Sokendai, Ibaraki, Japan
R. Ito
ULVAC, Inc, Chiba, Japan
Y. Iwashita, H. Tongu
Kyoto ICR, Uji, Kyoto, Japan
T. Nagata
ULVAC, Inc., Tsukuba, Japan

In recent years, it has been pointed out that the maximum accelerating gradient of a superconducting RF cavity can be increased by coating the inner surface of the cavity with a multilayer thin-film structure consisting of alternating insulating and superconducting layers. In this structure, the principal parameter that limits the performance of the cavity is the critical magnetic field or effective Hc1 at which vortices begin penetrating into the superconductor layer. This is predicted to depend on the combination of the film thickness. We made samples that have a NbN/SiO₂ thin-film structure on a pure Nb substrate with several layers of NbN film deposited using DC magnetron sputtering method. Here, we report the measurement results of effective Hc1 of NbN/SiO₂(30 nm)/Nb multilayer samples with thicknesses of NbN layers in the range from 50 nm to 800 nm by using the third-harmonic voltage method. Experimental results show that an optimum thickness exists, which increases the effective Hc1 by 23.8 %.

Slides THFUA2 [2.333 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THFUA2

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paper received ※ 03 July 2019 paper accepted ※ 05 July 2019 issue date ※ 14 August 2019

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THP023

RF Commissioning of the CBETA Main Linac Cryomodule

cavity, operation, LLRF, controls

881

N. Banerjee, J. Dobbins, G.H. Hoffstaetter, R.P.K. Kaplan, M. Liepe, C.W. Miller, P. Quigley, E.N. Smith, V. Veshcherevich
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: This work was performed through the support of New York State Energy Research and Development Agency (NYSERDA).
The Cornell BNL ERL Test Accelerator (CBETA) employs a superconducting Main Linac Cryomodule in order to perform multi-turn energy recovery operation. Optimizing the field stability of the low bandwidth SRF cavities in the presence of microphonics with limited available RF power is a challenging task. Despite of this, the Main Linac Cryomodule has been successfully used in CBETA to impart a maximum energy gain of 54 MeV, well above the energy gain requirement of CBETA. In this paper, we present an overview of our RF commissioning procedure including automatic coarse tuning, measurement of DAC and phase offsets. We further detail our microphonics measurements from our most recent run period.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP023

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paper received ※ 23 June 2019 paper accepted ※ 29 June 2019 issue date ※ 14 August 2019

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THP032

SRF Gun and SRF Linac Driven THz at ELBE Successfully in User Operation

gun, SRF, radiation, electron

915

R. Xiang, A. Arnold, P.E. Evtushenko, S. Kovalev, U. Lehnert, P.N. Lu, S. Ma, P. Michel, P. Murcek, A.A. Ryzhov, J. Schaber, Ch. Schneider, J. Teichert
HZDR, Dresden, Germany
H. Vennekate
RI Research Instruments GmbH, Bergisch Gladbach, Germany
I. Will
MBI, Berlin, Germany

Funding: The work was partly supported by the German Federal Ministry of Education and Research (BMBF) grant 05K12CR1 and Deutsche Forschungsgemeinschaft (DFG) project (XI 10⁶/2-1).
The first all-SRF accelerator driven THz source has been operated as a user facility since 2018 at ELBE radiation center. The CW electron beam is extracted from SRF gun II, accelerated to relativistic energies and compressed to sub-ps length in the ELBE SRF linac with a chicane. THz pulses are produced by pass-ing the short electron bunches through a diffraction radiator (CDR) and an undulator. The coherent THz power increases quadratically with bunch charge. The pulse energy up to 10 µJ at 0.3 THz with 100 kHz has been generated.

Poster THP032 [1.207 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP032

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paper received ※ 02 July 2019 paper accepted ※ 04 July 2019 issue date ※ 14 August 2019

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THP033

Cryogenic Systems Studies for the MINERVA 100 MeV Proton SC LINAC Project

cryogenics, cavity, cryomodule, proton

918

O. Kochebina, F. Dieudegard, T. Junquera
Accelerators and Cryogenic Systems, Orsay, France
D. Vandeplassche
SCK•CEN, Mol, Belgium

The construction of the first phase of the MYRRHA project (MINERVA: 100 MeV-4 mA proton Linac) was recently decided by the Belgium Government. In the long term, the MYRRHA project plans to construct an ADS demonstrator for the transmutation of long-lived radioactive waste. It will include a subcritical reactor of 100 MW thermal power and a CW proton Linac accelerator (600 MeV-4 mA). The main challenge of this Linac is an extremely high reliability performance to limit stresses and long restart procedures of the reactor. The MINERVA Linac includes 30 cryomodules housing 60 Single-Spoke SC cavities. A cryomodule prototype with its valve box is under construction at IPNO institute. The cavities operate at 352 MHz in a superfluid Helium bath at 2K. Therefore, a reliable SC Linac Cryogenic System is essential. This article presents the preliminary studies in this subject including the analysis of high thermal loads induced by the CW mode operation of cavities (950 W@2 K per cryomodule). A Cryogenic Refrigerator with an equivalent power capacity of 2645 W @4.5 K (3970 W with 1.5 overcapacity factor) is proposed. The constrains for the He distribution in the Linac tunnel are also discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP033

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paper received ※ 23 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019

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THP053

Analysis of the Results of the Tests of IFMIF Accelerating Units

cavity, cryomodule, SRF, vacuum

992

N. Bazin, S. Chel, M. Desmons, G. Devanz, H. Jenhani, O. Piquet
CEA-DRF-IRFU, France

The prototype IFMIF-EVEDA cryomodule encloses eight superconducting 175 MHz β=0.09 Half-Wave Resonators (HWR). They are designed together with the power coupler to accelerate a high intensity deuteron beam (125 mA) from to 5 to 9 MeV. Two cavity packages, complete with tuning system and power couplers, have been tested in a dedicated horizontal test cryostat - SaTHoRI (Satellite de Tests HOrizontal des Résonateurs IFMIF). The successful operational equivalent tests and tuning of the SRF accelerating units is reported.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP053

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paper received ※ 21 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019

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THP059

RF Incoming Inspection of 1.3 GHz Cryomodules for LCLS-II at SLAC National Accelerator Laboratory

cryomodule, cavity, HOM, controls

1014

S. Aderhold, C. Adolphsen, A. Burrill, D. Gonnella, J. Nelson
SLAC, Menlo Park, California, USA

Funding: This work was supported by the US DOE and the LCLS-II Project.
The main part of the SRF linac for the Linac Coherent Light Source II (LCLS-II) at SLAC National Accelerator Laboratory will consist of 35 cryomodules with superconducting RF cavities operating at 1.3 GHz. The cryomodules are assembled and tested at Fermi National Accelerator Laboratory and Thomas Jefferson National Accelerator Facility. Following the transport to SLAC, the cryomodules undergo several incoming inspection steps before ultimately being moved to the tunnel for installation in the linac. The RF part of the incoming inspection covers measurements of a number of parameters like cavity frequency spectrum, notch filter frequency of the higher order mode couplers and external quality factor Q_ext of the input coupler. The inspection results are compared to measurements at the partner labs prior to shipping and the nominal values in order to verify that the cryomodules have not been damaged during the transport and are ready for installation. We present an overview and analysis of the inspections for the cryomodules received to date.

Poster THP059 [1.223 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP059

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paper received ※ 02 July 2019 paper accepted ※ 02 July 2019 issue date ※ 14 August 2019

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THP061

Performance of FRIB Production Quarter-Wave and Half-Wave Resonators in Dewar Certification Tests

cavity, cryomodule, SRF, MMI

1023

W. Hartung, W. Chang, S.H. Kim, D. Norton, J.T. Popielarski, K. Saito, J.F. Schwartz, T. Xu, C. Zhang
FRIB, East Lansing, Michigan, USA

The Facility for Rare Isotope Beams (FRIB) is under construction at Michigan State University (MSU). The FRIB superconducting driver linac will accelerate ion beams to 200 MeV per nucleon. The driver linac requires 10⁴ quarter-wave resonators (QWRs, β = 0.041 and 0.085) and 220 half-wave resonators (HWRs, β = 0.29 and 0.54). The jacketed resonators are Dewar tested at MSU before installation into cryomodules. The cryomodules for β = 0.041, 0.085, and 0.29 have been completed and certified; 88% of the β = 0.54 HWRs have been certified (as of March 2019). Beam commissioning of the QWR cryomodules is in progress. The Dewar certification tests have provided valuable statistics on the performance of production QWRs and HWRs at 4.3 K and 2 K and on performance limits. Results will be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP061

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paper received ※ 12 July 2019 paper accepted ※ 13 August 2019 issue date ※ 14 August 2019

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THP063

Inivestigation of the Possibility of High Efficiency L-Band SRF Cavity for Medium-Beta Heavy Ion Multi-Charge-State Beams

cavity, emittance, cryomodule, heavy-ion

1035

S.M. Shanab, K. Saito, Y. Yamazaki
FRIB, East Lansing, Michigan, USA

Funding: This work was supported in part by the U.S. National Science Foundation, under Grant PHY-1102511 and by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661.
The possibility of L-band SRF elliptical cavity in order to accelerate heavy ion multi-charge-state beams is being investigated for accelerating energy higher than 200 MeV/u. A first simple analytic study was performed and the result showed that the longitudinal acceptance of 1288 MHz is sufficient for heavy-ion multi-charge-state (5 charge states) medium-beta linac. Encouraged this result, detail beam dynamic simulation took place. The cryogenic heat load is also calculated for this linac with taken into consideration cavity doping technology. In this paper, a summary of the beam dynamics and cryogen-ic heat load calculations for 1288 MHz linac for heavy-ion multi-charge-state (5 charge states) medium-beta beams.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP063

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paper received ※ 24 June 2019 paper accepted ※ 14 August 2019 issue date ※ 14 August 2019

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THP072

Development of HOM Absorbers for CW Superconducting Cavities in Energy Recovery Linac

HOM, cavity, superconducting-cavity, SRF

1060

T. Ota, S. Nakamura, K. Sato, M. Takasaki
Toshiba Energy Systems & Solutions Corporation, Keihin Product Operations, Yokohama, Japan
E. Kako, T. Konomi, H. Sakai, K. Umemori
KEK, Ibaraki, Japan
A. Miyamoto
Toshiba, Yokohama, Japan

Higher Order Modes (HOM) absorbers for superconducting cavities have been developing at TOSHIBA in collaboration with High Energy Accelerator Research Organization (KEK) since 2015. A new prototype HOM absorber for 1.3 GHz 9-cell superconducting cavity was fabricated. An AlN lossy dielectrics cylinder was brazed with a thin copper plate, and the cool-down tests by nitrogen gas was carried out. The copper plate and a copper cylinder were joined by electron beam welding. SUS flanges were electron beam welded to both ends of the copper cylinder to fabricate a whole prototype HOM absorber. Fabrication process of the prototype HOM absorber will be presented in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP072

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paper received ※ 21 June 2019 paper accepted ※ 03 July 2019 issue date ※ 14 August 2019

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THP074

Microphonics Noise Suppression with Observer Based Feedback

cavity, controls, SRF, resonance

1068

M. Keikha, K. Fong
TRIUMF, Vancouver, Canada
M. Moallem
SFU, Surrey, Canada

Funding: TRIUMF
Detuning of superconducting radio frequency (SRF) cavities is mainly caused by the Lorentz force, which is the radiation pressure induced by a high radio frequency (RF) field, and environmental mechanical vibrations that induce undesirable interference signals referred to as microphonics. Both of these influences can be described by a second order differential equation of the mechanical vibration modes of the cavity. In this paper we consider three dominant mechanical modes of the system and develop a control scheme based on input-output linearization. It is shown through simulation studies that the proposed control technique can successfully the suppress microphonic noise due to the SRF cavity¿s dynamics.

Poster THP074 [0.610 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP074

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paper received ※ 22 June 2019 paper accepted ※ 01 July 2019 issue date ※ 14 August 2019

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THP089

Development of Superconducting RF Double Spoke Cavity at IHEP

cavity, coupling, SRF, niobium

1114

Q. Zhou, F.S. He, W.M. Pan
IHEP, Beijing, People’s Republic of China

The China Spallation Neutron Source (CSNS) is de-signed to produce spallation neutrons. CSNS upgrade is planned to increase beam power by inserting a SRF linac after drift tube linac (DTL). IHEP is developing a 325MHz double spoke cavity at ¿0 of 0.5 for the CSNS SRF linac. The cavity shape was optimized to minimize Ep/Ea while keeping Bp/Ep reasonably low. Meanwhile, mechanical design was applied to check stress, Lorentz force detuning and microphonic effects, and to minimize pressure sensitivity. A new RF coupling scheme was pro-posed to avoid electrons hitting directly on ceramic win-dow. After fabrication and post processing of cavity, the cavity reached Bp of 120mT at E_acc = 13.8MV/m and Q₀ = 1.72·10¹⁰ under vertical test at 2K.

Poster THP089 [2.176 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP089

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paper received ※ 22 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019

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THP090

Characterization of SSR1 Cavities for PIP-II Linac

cavity, radiation, cryomodule, multipactoring

1120

A.I. Sukhanov, F.G. Garcia, B.M. Hanna, S. Kazakov, Y.M. Pischalnikov, O.V. Prokofiev, W. Schappert, I. Terechkine, V.P. Yakovlev, J.C. Yun
Fermilab, Batavia, Illinois, USA
C. Contreras-Martinez
FRIB, East Lansing, Michigan, USA
S. Samani
Queen Mary University of London, London, United Kingdom

A cryomodule of 325 MHz Single Spoke Resonator type 1 (SSR1) superconducting RF cavities is being built at Fermilab for the PIP-II project. Twelve SSR1 cavities were manufactured in industry in USA (10 cavities) and India (2 cavities) and delivered to Fermilab. In this paper we present results of characterization of fully integrated jacketed cavities with high power coupler and tuner at the Fermilab Spoke Test Cryostat (STC).

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP090

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paper received ※ 23 June 2019 paper accepted ※ 01 July 2019 issue date ※ 14 August 2019

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THP092

Status of Cryomodule Testing at CMTB for CW R&D

cavity, cryomodule, FEL, operation

1129

J. Branlard, V. Ayvazyan, A. Bellandi, J. Eschke, C. Gümüş, D. Kostin, K.P. Przygoda, H. Schlarb, J.K. Sekutowicz
DESY, Hamburg, Germany

Cryo Module Test Bench (CMTB) is a facility to perform tests on European XFEL like superconducting accelerating modules. The 120 kW Inductive Output Tube (IOT) installed in the facility allows driving the eight superconducting cavities inside the module under test in a vector-sum or single cavity control fashion with average Continuous Wave (CW) gradients higher than 20 MV/m. The scope of these tests is to evaluate the feasibility of upgrading European XFEL to CW operation mode. Following the successful tests done on a prototype module XM-3 the initial performance results on the production module XM50 will be presented in this paper. Because of European XFEL requirements, XM50 is equipped with modified couplers that allow a variable Loaded Quality factor(QL) to values higher than 4x10⁷. A cost relevant open question is the maximum QL that can be reached while maintaining the system within the European XFEL field stability specifications of 0.01 % in amplitude and 0.01 deg in phase. Because of this, the LLRF system capability of rejecting microphonic and RF disturbances, as well as Lorentz Force Detuning (LFD) related effects in open and closed loop is of prime interest.

Poster THP092 [1.514 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP092

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paper received ※ 25 June 2019 paper accepted ※ 30 June 2019 issue date ※ 14 August 2019

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THP096

ESS Prototype Cavities Developed at CEA Saclay

cavity, SRF, niobium, HOM

1143

E. Cenni
CEA-IRFU, Gif-sur-Yvette, France
M. Baudrier, P. Carbonnier, G. Devanz, X. Hanus, L. Maurice, J. Plouin, D. Roudier, P. Sahuquet
CEA-DRF-IRFU, 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 up to the final energy at 2 GeV. 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. CEA Saclay is in charge of the cavity prototypes that is designing, manufacturing, testing and integrating them into demonstrator cryomodules. We have manufactured 6 medium beta and 5 high beta cavities and we present here the latest results concerning these activities.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP096

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paper received ※ 22 June 2019 paper accepted ※ 02 July 2019 issue date ※ 14 August 2019

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THP103

Reconstruction of the Longitudinal Phase Space for the Superconducting CW HELIAC

heavy-ion, cavity, emittance, proton

1173

S. Lauber, K. Aulenbacher, W.A. Barth, C. Burandt, F.D. Dziuba, V. Gettmann, T. Kürzeder, J. List, M. Miski-Oglu
HIM, Mainz, Germany
K. Aulenbacher, W.A. Barth, C. Burandt, F.D. Dziuba, P. Forck, V. Gettmann, M. Heilmann, T. Kürzeder, S. Lauber, J. List, M. Miski-Oglu, T. Sieber, S. Yaramyshev
GSI, Darmstadt, Germany
K. Aulenbacher, F.D. Dziuba, S. Lauber
IKP, Mainz, Germany
H. Podlech, M. Schwarz
IAP, Frankfurt am Main, Germany

The superconducting (SC) heavy ion HElmholtz LInear ACcelerator (HELIAC) is under development at GSI in Darmstadt in cooperation with Helmholtz Institute Mainz (HIM) and Goethe-University Frankfurt (GUF). A novel design is used for the accelerating cavities, namely SC continuous wave (CW) multigap Crossbar H-Mode cavities. For this a dedicated beam dynamics layout - the EQUidistant mUltigap Structure (EQUUS) - has been carried out a couple of years ago and is under further development. In December 2018 the GSI High Charge State Injector (HLI) delivered heavy ion beam to the already commissioned first of series superconducting RF cavity. Proper 6D-matching to the CH cavity demands sufficient beam characterisation. Slit-grid emittance measurements provided for the transverse phase space determination. By measuring the longitudinal projection of the bunch with a Feschenko Monitor (Beam Shape Monitor), the bunch profile was obtained. With a dedicated algorithm, the full longitudinal phase space at the HLI-exit could be reconstructed from a set of BSM measurements. The basic reconstruction method, all relevant BSM measurements and the resulting phase space reconstruction will be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP103

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paper received ※ 19 June 2019 paper accepted ※ 29 June 2019 issue date ※ 14 August 2019

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THP104

Numerical Estimation of Beam Break-Up Instability in TESLA Cavities

dipole, cavity, solenoid, focusing

1178

V. Volkov, V.M. Petrov
BINP SB RAS, Novosibirsk, Russia

In this article the numerically estimated BBU instability behaviors of a 9 cell superconducting TESLA cavity are presented for first two pass-band trapped dipole modes (18 in all). The given BBU threshold current values are calculated by the method of beam energy gain averaging on phases of dipole mode fields. BBU instability behaviors in cases of applying the cavities in Linacs as well in Energy Recovery Linacs (ERLs) are considered. The BBU influence on beam emittance degradation is demonstrated. Examples for suppression of beam BBU oscillations by a solenoid focusing and applying of an external RF generator with a feedback are visualized.

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-THP104

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paper received ※ 23 June 2019 paper accepted ※ 02 July 2019 issue date ※ 14 August 2019

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FRCAA3

Industrial Cavity Production: Lessons Learned to Push the Boundaries of Nitrogen-Doping

cavity, niobium, cryomodule, SRF

1199

D. Gonnella, S. Aderhold, A. Burrill, M.C. Ross
SLAC, Menlo Park, California, USA
E. Daly, G.K. Davis, F. Marhauser, A.D. Palczewski, K.M. Wilson
JLab, Newport News, Virginia, USA
A. Grassellino, C.J. Grimm, T.N. Khabiboulline, O.S. Melnychuk, S. Posen, D.A. Sergatskov
Fermilab, Batavia, Illinois, USA

Funding: Work supported by US DOE Contract DE-AC02-76SF00515.
Nitrogen doping has been proven now in several labs to enhance Q₀ values of 1.3 GHz cavities in the gradient domain favored by CW operation. The choice of doping for the LCLS-II project has given the community a wealth of statistics and experience on the challenge of transferring the doping technology to industry. Overall, industry-produced nitrogen-doped cavities have shown excellent performance, however some technical issues have arisen. This talk focuses on lessons learned from the production of over 300 nitrogen-doped cavities for LCLS-II and how issues were mitigated to further improve performance. Finally, I will discuss pushing the boundaries of nitrogen-doping further by exploring different doping regimes in order to maintain excellent Q₀ performance, while reaching higher quench fields.

Slides FRCAA3 [16.880 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-FRCAA3

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paper received ※ 02 July 2019 paper accepted ※ 03 July 2019 issue date ※ 14 August 2019

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FRCAA4

Progress in SRF CH-Cavities for the HELIAC CW Linac at GSI

cavity, heavy-ion, cryomodule, MMI

1206

M. Miski-Oglu, K. Aulenbacher, W.A. Barth, C. Burandt, F.D. Dziuba, V. Gettmann, T. Kürzeder, S. Lauber, J. List, S. Yaramyshev
HIM, Mainz, Germany
K. Aulenbacher, W.A. Barth, C. Burandt, F.D. Dziuba, V. Gettmann, M. Heilmann, T. Kürzeder, S. Lauber, J. List, A. Rubin, A. Schnase, S. Yaramyshev
GSI, Darmstadt, Germany
K. Aulenbacher, F.D. Dziuba, J. List
KPH, Mainz, Germany
M. Basten, M. Busch, T. Conrad, H. Podlech, M. Schwarz
IAP, Frankfurt am Main, Germany
S. Lauber
IKP, Mainz, Germany

The machine beam commissioning is a major milestone of the R&D for the superconducting heavy ion continuous wave linear accelerator HELIAC of Helmholtz Institute Mainz (HIM) and GSI developed in collaboration with IAP Goethe-University Frankfurt. During successful beam commissioning of the superconducting 15-gap Crossbar H-mode cavity at GSI Helmholtzzentrum für Schwerionenforschung heavy ions up to the design beam energy have been accelerated. The design acceleration gain of 3.5 MeV has been reached with full transmission for heavy ion beams of up to 1.5 particle mueA. We present fabrication experience and results of off-line and on-line cavity performance. The next step is the procurement and commissioning of so called ’Advanced Demonstrator’ - the first of series cryomodule for the entire accelerator HELIAC. Results of further Demonstrator beam tests, as well as the status of the Advanced demonstrator project will be reported.

Slides FRCAA4 [9.864 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-FRCAA4

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paper received ※ 23 June 2019 paper accepted ※ 02 July 2019 issue date ※ 14 August 2019

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FRCAB3

The Design of an Automated High-Pressure Rinsing System for SRF Cavity and the Outlook for Future Automated Cleanroom on Strings Assembly

cavity, controls, SRF, alignment

1216

H. Guo, Q.W. Chu, Y. He, C.L. Li, Y.K. Song, T. Tan, Z.M. You
IMP/CAS, Lanzhou, People’s Republic of China

High-pressure rinsing (HPR) and cavity assembly are two critical steps in cavity post-processing. Traditionally, high-pressure rinsing processing is based on ultra pure water system, pump, rinsing wand and simple-functional control system; cavity assembly processing is based on simple fixtures, wrenches, bolts and nuts. Beside the equipments, at least two operators are required in either of these two processing. Operators and their actions could bring mistakes and cause extra airborne particle contamination in cleanroom. To avoid the risk from labors, a robot has been introduced in IMP cleanroom for HPR assisting and assembly assisting. Labor cost and cavity RF test results are compared between the circumstances with and without robot assisting. In this work, an automated HPR system that has been designed and will be installed in IMP cleanroom will be presented. In addition, a future automated cleanroom on strings assembly will be discussed as well.

Slides FRCAB3 [6.203 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2019-FRCAB3

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paper received ※ 03 July 2019 paper accepted ※ 12 July 2019 issue date ※ 14 August 2019

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