Keyword: SRF
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MOZGBF4 Evolution of the Superconducting Linac Output Energy at the Spallation Neutron Source cavity, cryomodule, operation, linac 73
 
  • S.-H. Kim, D.E. Anderson, M.T. Crofford, M. Doleans, J. Galambos, S.W. Gold, M.P. Howell, M.A. Plum, D.J. Vandygriff
    ORNL, Oak Ridge, Tennessee, USA
  • R. Afanador, D.L. Barnhart, B. DeGraff, J.D. Mammosser, C.J. McMahan, T.S. Neustadt, C.C. Peters, J. Saunders, D.M. Vandygriff
    ORNL RAD, Oak Ridge, Tennessee, USA
  
  Funding: This work was supported by SNS through UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE.
The SNS linac out­put en­ergy has in­creased since the start of neu­tron pro­duc­tion in FY2007. The var­i­ous im­prove­ments that con­tributed to the in­crease of the linac out­put en­ergy are LLRF/con­trol sys­tem im­prove­ment, high volt­age con­verter mod­u­la­tor sys­tem im­prove­ment, high-power RF sys­tem im­prove­ment, cry­omod­ule re­pairs, spare cry­omod­ule de­vel­op­ment and ac­cel­er­at­ing gra­di­ent im­prove­ment through in-situ plasma pro­cess­ing. In this paper, the his­tory of the SNS SCL out­put en­ergy is re­ported, and plans for the near-term fu­ture and for the Pro­ton Power Up­grade (PPU) pro­ject are also pre­sented. 		 
slides icon Slides MOZGBF4 [34.185 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOZGBF4  
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MOPMF072 On the Feasibility of a Pulsed 14 TeV C.M.E. Muon Collider in the LHC Tunnel collider, luminosity, proton, acceleration 296
 
  • V.D. Shiltsev, D.V. Neuffer
    Fermilab, Batavia, Illinois, USA
  
  We will con­sider tech­ni­cal fea­si­bil­ity, key ma­chine pa­ra­me­ters and major chal­lenges of the re­cently pro­posed 14 TeV c.m.e. muon-muon col­lider in the LHC tun­nel.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF072  
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MOPML034 Development Status of Superconducting RF Transmission Electron Microscope cavity, acceleration, LLRF, gun 481
 
  • N. Higashi, A. Enomoto, Y. Funahashi, T. Furuya, X.J. Jin, Y. Kamiya, S. Michizono, F. Qiu, M. Yamamoto
    KEK, Ibaraki, Japan
  • S. Yamashita
    University of Tokyo, Tokyo, Japan
  
  Now we are de­vel­op­ing a new type of trans­mis­sion elec­tron mi­cro­scope (TEM) em­ploy­ing the ac­cel­er­a­tor tech­nolo­gies. In place of a DC ther­mal gun gen­er­ally used in con­ven­tional TEMs, we apply a pho­to­cath­ode gun and a spe­cial-shaped su­per­con­duct­ing cav­ity, named two-mode cav­ity. The two-mode cav­ity has two res­o­nant modes of TM010 (1.3 GHz) and TM020 (2.6 GHz). To su­per­im­pose these, we can sup­press the in­crease of the en­ergy spread, which is needed for the high-spa­tial-res­o­lu­tion TEMs. We have al­ready de­vel­oped some pro­to­types of the pho­to­cath­ode gun and two-mode cav­ity, and now in the mid­dle of the per­for­mance tests. In this pre­sen­ta­tion, we will show the lat­est sta­tus of the de­vel­op­ment.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML034  
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MOPML053 Mu*STAR Accelerator-Driven Subcritical Reactors Burning Spent Nuclear Fuel at Light-Water-Reactor Sites target, site, neutron, operation 524
 
  • R.P. Johnson, R.J. Abrams, M.A. Cummings, T.J. Roberts
    Muons, Inc, Illinois, USA
  
  This pro­ject will use mod­el­ing and sim­u­la­tion tools to op­ti­mize many as­pects of the Mu*STAR de­sign and begin to ex­plore ac­ci­dent sce­nar­ios. At pre­sent we have a con­cep­tual de­sign of the ac­cel­er­a­tor, the re­ac­tor, the spal­la­tion tar­get, and the frac­tional dis­til­la­tion to sep­a­rate volatile fis­sion prod­ucts. Our GAIN pro­ject with ORNL is prepar­ing a de­sign of the Fuel Pro­cess­ing Plant that will con­vert spent nu­clear fuel into the molten-salt fuel for Mu*STAR. This in­cludes all of the nu­clear com­po­nents, but not such things as the tur­bine and gen­er­a­tor, phys­i­cal plant, con­trol and mon­i­tor­ing sys­tems, etc. We cur­rently have basic sim­u­la­tions of the re­ac­tor neu­tron­ics, and a start at cal­cu­lat­ing the fuel evo­lu­tion. These have used MCNP and ORI­GEN, and ini­tial re­sults have been re­port­ed1. This pro­ject will sup­port the use of ad­di­tional neu­tron­ics and multi-physics codes, en­abling a much more thor­ough analy­sis of the sys­tem.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML053  
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TUYGBE2 CBETA, the 4-Turn ERL with SRF and Single Return Loop electron, linac, gun, cryomodule 635
 
  • G.H. Hoffstaetter, N. Banerjee, J. Barley, A.C. Bartnik, I.V. Bazarov, D.C. Burke, J.A. Crittenden, L. Cultrera, J. Dobbins, S.J. Full, F. Furuta, R.E. Gallagher, M. Ge, C.M. Gulliford, B.K. Heltsley, R.P.K. Kaplan, V.O. Kostroun, Y. Li, M. Liepe, W. Lou, C.E. Mayes, J.R. Patterson, P. Quigley, D.M. Sabol, D. Sagan, J. Sears, C.H. Shore, E.N. Smith, K.W. Smolenski, V. Veshcherevich, D. Widger
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • J.S. Berg, S.J. Brooks, C. Liu, G.J. Mahler, F. Méot, R.J. Michnoff, M.G. Minty, S. Peggs, V. Ptitsyn, T. Roser, P. Thieberger, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, F.J. Willeke, H. Witte
    BNL, Upton, Long Island, New York, USA
  • D. Douglas
    JLab, Newport News, Virginia, USA
  • J.K. Jones
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • D. Jusic
    Cornell University, Ithaca, New York, USA
  • D.J. Kelliher
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
  • B.C. Kuske, M. McAteer, J. Völker
    HZB, Berlin, Germany
  
  Funding: Supported by NSF award DMR-0807731, DOE grant DE-AC02-76SF00515, and NYSERDA.
A col­lab­o­ra­tion be­tween Cor­nell Uni­ver­sity and Brookhaven Na­tional Lab­o­ra­tory has de­signed and is con­struct­ing CBETA, the Cor­nell-BNL ERL Test Ac­cel­er­a­tor on the Cor­nell cam­pus. The ERL tech­nol­ogy that has been pro­to­typed at Cor­nell for many years is being used for this new ac­cel­er­a­tor, in­clud­ing a DC elec­tron source and an SRF in­jec­tor Linac with world-record cur­rent and nor­mal­ized bright­ness in a bunch train, a high-cur­rent linac cry­omod­ule op­ti­mized for ERLs, a high-power beam stop, and sev­eral di­ag­nos­tics tools for high-cur­rent and high-bright­ness beams. BNL has de­signed multi-turn ERLs for sev­eral pur­pose, dom­i­nantly for the elec­tron beam of eRHIC, its Elec­tron Ion Col­lider (EIC) pro­ject and for the as­so­ci­ated fast elec­tron cool­ing sys­tem. Also in JLEIC, the EIC de­signed at JLAB, an ERL is en­vi­sioned to be used for elec­tron cool­ing. The num­ber of trans­port lines in an ERL is min­i­mized by using re­turn arcs that are com­prised of a Fixed Field Al­ter­nat­ing-gra­di­ent (FFA) de­sign. This tech­nique will be tested in CBETA, which has a sin­gle re­turn for the 4-beam en­er­gies with strongly-fo­cus­ing per­ma­nent mag­nets of Hal­bach type. The high-bright­ness beam with 150~MeV and up to 40~mA will have ap­pli­ca­tions be­yond ac­cel­er­a­tor re­search, in in­dus­try, in nu­clear physics, and in X-ray sci­ence. Low cur­rent elec­tron beam has al­ready been sent through the most rel­e­vant parts of CBETA, from the DC gun through both cry­omod­ules, through one of the 8 sim­i­lar sep­a­ra­tor lines, and through one of the 27 sim­i­lar FFA struc­tures. Fur­ther con­struc­tion is en­vi­sioned to lead to a com­mis­sion­ing start for the full sys­tem early in 2019. 		 
slides icon Slides TUYGBE2 [17.343 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUYGBE2  
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TUPAF014 Beam Dynamics Studies For the IFMIF-DONES SRF-Linac linac, cryomodule, cavity, solenoid 687
 
  • L. Du, N. Bazin, N. Chauvin, S. Chel, J. Plouin
    CEA/IRFU, Gif-sur-Yvette, France
  
  The DONES (DEMO ori­ented neu­tron source) pro­ject is aimed at con­struct­ing a DEMO of IFMIF to pro­vide suf­fi­cient ma­te­r­ial dam­age [1]. In the SRF-Linac of this pro­ject, losses can cause harm­ful ma­te­r­ial ac­ti­va­tion and must be main­tained much less than 1W/m. It's a chal­lenge to keep losses at such a low level with high beam power and high space charge. This paper pre­sents two de­signs of the DONES SRF-Linac, one with 4 cry­omod­ules and an­other with 5 cry­omod­ules. The de­sign de­tails to re­duce the losses and the multi-par­ti­cle sim­u­la­tion re­sults will be shown. The er­rors stud­ies for these re­sults will also be dis­cussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF014  
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TUPAF076 Design of PIP-II Medium Energy Beam Transport vacuum, linac, kicker, cryomodule 905
 
  • A. Saini, C.M. Baffes, A.Z. Chen, V.A. Lebedev, L.R. Prost, A.V. Shemyakin
    Fermilab, Batavia, Illinois, USA
  
  Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics
The Pro­ton Im­prove­ment Plan-II (PIP-II) is a pro­posed up­grade for the ac­cel­er­a­tor com­plex at Fer­mi­lab. The cen­tral piece of PIP-II is a su­per­con­duct­ing radio fre­quency (SRF) 800 MeV linac ca­pa­ble of op­er­at­ing in both CW and pulse regimes. The PIP-II linac com­prises a warm front-end that in­cludes a H− ion source ca­pa­ble of de­liv­er­ing 15-mA, 30-keV DC or pulsed beam, a Low En­ergy Beam Trans­port (LEBT), a 162.5 MHz, CW Ra­dio-Fre­quency Quadru­pole (RFQ) ac­cel­er­at­ing the ions to 2.1 MeV and, a 14-m Medium En­ergy Beam Trans­port (MEBT) be­fore beam is in­jected into SRF part of the linac. This paper pre­sents the PIP-II MEBT de­sign and, dis­cusses op­er­a­tional fea­tures and con­sid­er­a­tions that lead to ex­ist­ing op­tics de­sign such as bunch by bunch chop­ping sys­tem, min­i­miza­tion of ra­di­a­tion com­ing to the warm front-end from the SRF linac using a con­crete wall, a ro­bust vac­uum pro­tec­tion sys­tem etc. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF076  
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TUZGBE5 A Combined Temperature and Magnetic Field Mapping System for SRF Cavities cavity, operation, niobium, experiment 1228
 
  • J.M. Köszegi, K. Alomari, J. Knobloch, O. Kugeler, B. Schmitz
    HZB, Berlin, Germany
  
  In the past decade, a sig­nif­i­cant im­prove­ment of SRF cav­ity per­for­mance has been achieved, yet a num­ber of per­for­mance lim­it­ing mech­a­nisms, such as mag­netic flux trap­ping, still exist. We pre­sent a di­ag­nos­tics tool which com­bines flux ex­pul­sion mea­sure­ment dur­ing the su­per­con­duct­ing phase tran­si­tion with tem­per­a­ture map­ping dur­ing op­er­a­tion. This sys­tem has a time res­o­lu­tion for both tem­per­a­ture and mag­netic field map­ping of 2 ms for full cav­ity cov­er­age, so that short-lived events, in­clud­ing cav­ity quenches, can eas­ily be re­solved.  
slides icon Slides TUZGBE5 [1.358 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUZGBE5  
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TUPMF002 A Cu Photocathode for the Superconducting RF Photoinjector of BERLinPro cathode, gun, cavity, laser 1247
 
  • J. Kühn, M. Bürger, A. Frahm, A. Jankowiak, T. Kamps, G. Klemz, G. Kourkafas, A. Neumann, N. Ohm, M. Schmeißer, M. Schuster, J. Völker
    HZB, Berlin, Germany
  • P. Murcek, J. Teichert
    HZDR, Dresden, Germany
  
  The ini­tial com­mis­sion­ing of the Su­per­con­duct­ing RF (SRF) pho­toin­jec­tor is done with a Cu pho­to­cath­ode due to its ro­bust­ness with re­gard to in­ter­ac­tions with the SRF cav­ity of the in­jec­tor. Here we pre­sent the prepa­ra­tion and char­ac­ter­i­za­tion of a Cu pho­to­cath­ode plug and the di­ag­nos­tics to in­sert the pho­to­cath­ode in the back wall of the SRF cav­ity. A poly­crys­talline bulk Cu plug was pol­ished, par­ti­cle free cleaned and char­ac­ter­ized by x-ray pho­to­elec­tron spec­troscopy. Dur­ing the trans­fer of the pho­to­cath­ode in­sert into the gun mod­ule the whole process was con­trolled by sev­eral di­ag­nos­tic tools mon­i­tor­ing the in­sert po­si­tion as well as RF, vac­uum and cryo­genic sig­nals. We dis­cuss the chal­lenges of the pho­to­cath­ode trans­fer into an SRF cav­ity and how they can be tack­led.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF002  
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TUPML053 The BERLinPro SRF Photoinjector System - From First RF Commissioning to First Beam cathode, cavity, operation, solenoid 1660
 
  • A. Neumann, D. Böhlick, M. Bürger, P. Echevarria, A. Frahm, H.-W. Glock, F. Göbel, S. Heling, K. Janke, A. Jankowiak, T. Kamps, S. Klauke, G. Klemz, J. Knobloch, G. Kourkafas, J. Kühn, O. Kugeler, N. Leuschner, N. Ohm, E. Panofski, H. Plötz, S. Rotterdam, M.A.H. Schmeißer, M. Schuster, H. Stein, Y. Tamashevich, J. Ullrich, A. Ushakov, J. Völker
    HZB, Berlin, Germany
  
  Funding: The work is funded by the Helmholtz-Association, BMBF, the state of Berlin and HZB.
Helmholtz-Zen­trum Berlin (HZB) is cur­rently con­struct­ing a high av­er­age cur­rent su­per­con­duct­ing (SC) ERL as a pro­to­type to demon­strate low nor­mal­ized beam emit­tance of 1 mm-mrad at 100 mA and short pulses of about 2 ps. To at­tain the re­quired beam prop­er­ties, an SRF based photo-in­jec­tor sys­tem was de­vel­oped and dur­ing the past year un­der­went RF com­mis­sion­ing and was setup within a ded­i­cated di­ag­nos­tics beam­line called Gun­lab to an­a­lyze beam dy­nam­ics of both, a cop­per cath­ode and a Cs2KSb cath­ode as well as their quan­tum ef­fi­ciency at UV and green light re­spec­tively. The medium power pro­to­type - a first stage to­wards the final high power 100 mA de­sign - pre­sented here fea­tures a 1.4 x λ/2 cell SRF cav­ity with a nor­mal-con­duct­ing, high quan­tum ef­fi­ciency CsK2Sb cath­ode, im­ple­ment­ing a mod­i­fied HZDR-style cath­ode in­sert. This in­jec­tor po­ten­tially al­lows for 6 mA beam cur­rent and up to 3.5 MeV ki­netic en­ergy, lim­ited by the mod­i­fied twin TTF-III fun­da­men­tal power cou­plers. In this con­tri­bu­tion, the first RF com­mis­sion­ing re­sults of the photo-in­jec­tor mod­ule will be pre­sented in­clud­ing dark cur­rent analy­sis as well as mea­sured beam prop­er­ties with an ini­tially in­stalled Cop­per cath­ode. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML053  
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WEYGBF3 Nb3Sn Multicell Cavity Coating at JLab cavity, niobium, factory, superconductivity 1798
 
  • U. Pudasaini, M.J. Kelley
    The College of William and Mary, Williamsburg, Virginia, USA
  • G. Ciovati, G.V. Eremeev, M.J. Kelley, C.E. Reece
    JLab, Newport News, Virginia, USA
  • M.J. Kelley
    Virginia Polytechnic Institute and State University, Blacksburg, USA
  • I.P. Parajuli, MNS. Sayeed
    ODU, Norfolk, Virginia, USA
  
  Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics.
Fol­low­ing en­cour­ag­ing re­sults with Nb3Sn-coated R&D cav­i­ties, the ex­ist­ing coat­ing sys­tem was up­graded to allow for Nb3Sn coat­ing of CEBAF ac­cel­er­a­tor cav­i­ties. The up­grade was de­signed to allow Nb3Sn coat­ing of orig­i­nal CEBAF 5-cell cav­i­ties with the vapor dif­fu­sion tech­nique. Sev­eral CEBAF cav­i­ties were coated in the up­graded sys­tem to in­ves­ti­gate vapor dif­fu­sion coat­ings on ex­tended struc­tures. Wit­ness sam­ples coated along with the cav­i­ties were char­ac­ter­ized with ma­te­r­ial sci­ence tech­niques, while coated cav­i­ties were mea­sured at 4 and 2 K. The progress, lessons learned, and the path­for­ward are dis­cussed. 		 
slides icon Slides WEYGBF3 [2.381 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEYGBF3  
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WEPAK012 Developing Kalman Filter Based Detuning Control with a Digital SRF CW Cavity Simulator cavity, controls, FPGA, LLRF 2114
 
  • A. Ushakov, P. Echevarria, A. Neumann
    HZB, Berlin, Germany
  
  Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of the Helmholtz Association
Con­tin­u­ous wave op­er­ated su­per­con­duct­ing cav­i­ties ex­pe­ri­enc­ing small net beam load­ing and thus op­er­ate po­ten­tially at nar­row band­width re­quire pre­cise de­tun­ing con­trol to reach the high sta­bil­ity re­quire­ments for RF fields within fa­cil­i­ties as FEL or ERL based pho­ton sources. Es­pe­cially mi­cro­phon­ics com­pen­sa­tion down to sub-hertz de­tun­ing regime be­sides im­prov­ing sta­bil­ity re­duces the risk of rise of Lorentz force de­tun­ing dri­ven pon­dero­mo­tive in­sta­bil­i­ties. Usu­ally the com­plex and sec­ond order na­ture of the me­chan­i­cal to RF de­tun­ing trans­fer func­tions of cav­ity and cav­ity-tuner sys­tem re­quire for more ad­vanced con­trol schemes. In this paper we will show the ap­pli­ca­tion of a Kalman fil­ter based de­tun­ing es­ti­ma­tor al­go­rithm first in­tro­duced dur­ing IPAC2017 [1] to the SRF cav­ity sim­u­la­tor de­vel­oped at Helmholtz Zen­trum Berlin [2]. Re­sults using the al­go­rithm in ob­server mode to de­tun­ing com­pen­sa­tion at­tempts in closed loop mode are pre­sented.
* A. Ushakov, P. Echevarria, A. Neumann, Proc. of IPAC 2017, Copenhagen, Denmark 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAK012  
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WEPAK013 SRF Cavity Simulator for LLRF Algorithms Debugging cavity, controls, LLRF, FPGA 2118
 
  • P. Echevarria, J. Knobloch, A. Neumann, A. Ushakov
    HZB, Berlin, Germany
  • E. Aldekoa, J. Jugo
    University of the Basque Country, Faculty of Science and Technology, Bilbao, Spain
  
  Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of Helmholtz Association
The avail­abil­ity of nio­bium su­per­con­duct­ing cav­i­ties, ei-ther due to a lack of a real cav­ity or due to the time needed for the ex­per­i­ment set up (vac­uum, cryo­gen­ics, ca­bling, etc.), is lim­ited, and thus it can block or delay the de­velop-ment of new al­go­rithms such as low level RF con­trol. Hard­ware-in-the-loop sim­u­la­tions, where an ac­tual cav­ity is re­placed by an elec­tron­ics sys­tem, can help to solve this issue. In this paper we pre­sent a Cav­ity Sim­u­la­tor im­ple-mented in a Na­tional In­stru­ments PXI equipped with an FPGA mod­ule. This mod­ule op­er­ates with one in­ter­medi-ate fre­quency input which is IQ-de­mod­u­lated and fed to the elec­tri­cal cav­ity's model, where the trans­mit­ted and re-flected volt­ages are cal­cu­lated and IQ-mod­u­lated to gener-ate two in­ter­me­di­ate fre­quency out­puts. Some more ad-vanced fea­tures such as me­chan­i­cal vi­bra­tion modes dri­ven by Lorentz-force de­tun­ing or ex­ter­nal mi­cro­phon­ics have also been im­ple­mented. This Cav­ity Sim­u­la­tor is planned to be con­nected to an mTCA chas­sis to close the loop with a LLRF con­trol sys­tem. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAK013  
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WEPAL005 Beam Size Measurement and PSF Evaluate of KB Mirror Monitor at SSRF storage-ring, optics, electron, photon 2151
 
  • D.C. Zhu, J.S. Cao, Y.F. Sui, J.H. Yue
    IHEP, Beijing, People's Republic of China
  
  Funding: Work supported by National Nature Science Foundation of China(11605213)
A Kirk­patrick Baez mir­ror imag­ing sys­tem was de­signed and in­stalled to mea­sure the trans­verse beam size and emit­tance of SSRF stor­age ring. Two crossed cylin­dri­cal mir­rors are used to image the di­pole source point in the hor­i­zon­tal and ver­ti­cal di­rec­tion. Both mir­rors could be moved in and out in order to in­ter­change­able with an orig­i­nal X-ray pin­hole sys­tem. Hard X-ray with peak en­ergy of 20.5 keV was fo­cused at the X-ray scin­til­la­tor cam­era. Aber­ra­tion and point spread func­tion which would cause image blur were eval­u­ated. Sys­tem com­mis­sion­ing and op­ti­miza­tion have been done. PSF mea­sure­ment was ac­quired using beam based cal­i­bra­tion scheme by vary­ing the beam im­ages with dif­fer­ent quadru­pole set­tings and fit­ting them with the cor­re­spond­ing the­o­ret­i­cal beam sizes. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL005  
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WEPAL039 LCLS-II Gun/Buncher LLRF System Design gun, LLRF, cavity, controls 2258
 
  • G. Huang, K.S. Campbell, L.R. Doolittle, J.A. Jones, Q. Qiang, C. Serrano
    LBNL, Berkeley, California, USA
  • S. Babel, A.L. Benwell, M. Boyes, G.W. Brown, D. Cha, J.H. De Long, J.A. Diaz Cruz, B. Hong, A. McCollough, A. Ratti, C.H. Rivetta, D. Rogind, F. Zhou
    SLAC, Menlo Park, California, USA
  • R. Bachimanchi, C. Hovater, D.J. Seidman
    JLab, Newport News, Virginia, USA
  • B.E. Chase, E. Cullerton, J. Einstein-Curtis, D.W. Klepec
    Fermilab, Batavia, Illinois, USA
  • J.A. Diaz Cruz
    CSU, Fort Collins, Colorado, USA
  
  Funding: This work was supported by the LCLS-II Project and the U.S. Department of Energy, Contract n. DE-AC02-05CH11231.
For a free elec­tron laser, the sta­bil­ity of in­jec­tor is crit­i­cal to the final elec­tron beam pa­ra­me­ters, e.g., beam en­ergy, beam ar­rival time, and even­tu­ally it de­ter­mines the pho­ton qual­ity. The LCLS-II pro­ject's in­jec­tor con­tains a VHF cop­per cav­ity as the gun and a two-cell L-band cop­per cav­ity as its buncher. The cav­ity de­signs are in­her­ited from the APEX de­sign, but re­quires more field sta­bil­ity than demon­strated in APEX op­er­a­tion. The gun LLRF sys­tem de­sign uses a con­nec­tor­ized RF front end and low noise dig­i­tizer, to­gether with the same gen­eral pur­pose FPGA car­rier board used in the LCLS-II SRF LLRF sys­tem. The buncher LLRF sys­tem di­rectly adopts the SRF LLRF chas­sis de­sign, but pro­grams the con­troller to run the nor­mal con­duct­ing cav­i­ties. In this paper, we de­scribe the gun/buncher LLRF sys­tem de­sign, in­clud­ing the hard­ware de­sign, the firmware de­sign and bench test. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL039  
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WEPAL055 TPS Beam Trip Analysis and Dose Distribution radiation, kicker, neutron, storage-ring 2302
 
  • B.Y. Chen, F.Y. Chang, S. Fann, C.S. Huang, C.H. Kuo, T.Y. Lee, C.C. Liang, W.Y. Lin, Y.C. Lin, Y.-C. Liu
    NSRRC, Hsinchu, Taiwan
  
  Fail­ure analy­sis dur­ing TPS users op­er­a­tion is im-por­tant to im­prove the per­for­mance of the TPS stor­age ring. In this re­port, we dis­cuss the par­tic­u­lar ra­di­a­tion dose pat­terns, rel­e­vant to dif­fer­ent beam trips, and the de­vel­op­ment of a tool to help us analyse this dose dis­tri-bu­tion. We will use this analysing tool to train our abil­ity for fu­ture fail­ure analy­sis to shorten the time it takes to find the prob­lem.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL055  
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WEPMF012 Power Requirement and Preliminary Coupler Design for the eRHIC Crab Cavity System cavity, operation, proton, electron 2394
 
  • S. Verdú-Andrés, I. Ben-Zvi, D. Holmes, Q. Wu
    BNL, Upton, Long Island, New York, USA
  • I. Ben-Zvi
    Stony Brook University, Stony Brook, USA
  
  Funding: Work supported by Brookhaven Science Associates LLC under contract no. DE-SC0012704 with the U.S. Department of Energy.
Crab cav­i­ties are de­flect­ing cav­i­ties op­er­ated in such a way that the bunch cen­ter is in syn­chro­nism with the zero-cross­ing kick volt­age. In that case, beam load­ing is zero for an on-axis beam. The crab cav­ity sys­tem of the fu­ture elec­tron-ion col­lider eRHIC will ma­nip­u­late 275 GeV pro­ton beams. At high en­er­gies, the beam off­set can be as large as 2 mm (in­clud­ing me­chan­i­cal and elec­tri­cal off­set tol­er­ances). The beam load­ing re­sult­ing from such off­set can greatly incur in large power re­quire­ments to the RF am­pli­fier. The choice of ex­ter­nal Q for the Fun­da­men­tal Power Cou­pler (FPC) is crit­i­cal to limit the power re­quire­ment to prac­ti­cal val­ues. The loaded Q of the eRHIC crab cav­i­ties is mainly gov­erned by the ex­ter­nal Q of the FPC, so the ex­ter­nal Q will also de­fine the cav­ity band­width and thus the tun­ing re­quire­ments to coun­ter­act fre­quency tran­sients from ex­ter­nal per­tur­ba­tions. This paper dis­cusses the choice of ex­ter­nal Q for the FPC of the eRHIC crab cav­i­ties and in­tro­duces the de­sign of a pre­lim­i­nary FPC an­tenna con­cept that would pro­vide the ap­pro­pri­ate ex­ter­nal Q. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF012  
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WEPMF036 RF Test Result of a BNL N-Doped 500 MHz B-Cell Cavity at Cornell cavity, vacuum, superconducting-cavity, niobium 2440
 
  • F. Furuta, M. Ge, T. Gruber, J.J. Kaufman, M. Liepe, J.T. Maniscalco, J. Sears
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • F. Gao, J. Rose
    BNL, Upton, Long Island, New York, USA
  
  Cor­nell's SRF group has col­lab­o­rated with Brookhaven Na­tional Lab­o­ra­tory (BNL) on one 500 MHz CESR type SRF "B-cell" cav­ity (BNL B-cell) for the Na­tional Syn­chro­tron Light Source II. Cor­nell has been re­spon­si­ble for RF sur­face prepa­ra­tion, ver­ti­cal test­ing, and short cav­ity string as­sem­bly. As a state-of-the-art sur­face prepa­ra­tion pro­to­col, Cor­nell se­lected Ni­tro­gen dop­ing for the BNL B-cell. N-dop­ing has been well demon­strated and es­tab­lished to push the cav­ity qual­ity fac­tor (Q0) higher in 1.3GHz SRF cav­i­ties at many lab­o­ra­to­ries. Cor­nell cal­cu­lated that N-dop­ing could also be ben­e­fi­cial on a 500MHz SRF cav­ity, with a po­ten­tial to in­crease its Q0 by a fac­tor of two com­pared with the tra­di­tional chem­i­cal pol­ish­ing based sur­face prepa­ra­tion pro­to­col. Here we re­port on the de­tailed sur­face prepa­ra­tion and ver­ti­cal test re­sult of the BNL B-cell.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF036  
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WEPMF037 HF Free Bipolar Electro-Polishing Studies on Niobium SRF Cavities at Cornell With Faraday Technology cavity, niobium, MMI, radio-frequency 2443
 
  • F. Furuta, M. Ge, T. Gruber, J.J. Kaufman, P.N. Koufalis, M. Liepe, J. Sears
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • T.D. Hall, M.E. Inman, R. Radhakrishnan, S.T. Snyder, E.J. Taylor
    Faraday Technology, Inc., Clayton, Ohio, USA
  
  Cor­nell's SRF group and Fara­day Tech­nol­ogy have been col­lab­o­rat­ing on two phase-II SBIR pro­jects. One of them is the de­vel­op­ment and com­mis­sion­ing of a 9-cell scale HF free Bipo­lar Elec­tro-Pol­ish­ing (BEP) sys­tem. Fara­day Tech­nol­ogy has up­graded their 1.3 GHz sin­gle-cell BEP sys­tem for host­ing 9-cell cav­i­ties. Ini­tial com­mis­sion­ing of the new sys­tem was done with a three sin­gle-cell cav­ity string, and high a gra­di­ent of 40MV/m was demon­strated dur­ing the RF tests at Cor­nell. After this suc­cess with the test string, the 9-cell cav­ity was processed with the new sys­tem at Fara­day and RF test was per­formed at Cor­nell. Here we re­port de­tailed re­sults from these 9-cell scale HF free BEP stud­ies.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF037  
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WEPMF038 Microphonics Suppression in the CBETA Linac Cryomodules cavity, linac, cryomodule, controls 2447
 
  • N. Banerjee, J. Dobbins, F. Furuta, G.H. Hoffstaetter, R.P.K. Kaplan, M. Liepe, 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. The linac cryomodules were constructed with funding from the National Science Foundation.
The Cor­nell-BNL ERL Test Ac­cel­er­a­tor (CBETA) is a new multi-turn en­ergy re­cov­ery linac cur­rently under con­struc­tion at Cor­nell Uni­ver­sity. It uses two su­per­con­duct­ing linacs, both of which are sus­cep­ti­ble to mi­cro­phon­ics de­tun­ing. The high-cur­rent in­jec­tor ac­cel­er­ates elec­trons to 6 MeV and the main linac ac­cel­er­ates and de­cel­er­ates elec­trons by 36 MeV. In this paper, we dis­cuss var­i­ous mea­sures taken to re­duce vi­bra­tions caused by in­sta­bil­i­ties and flow tran­sients in the cryo­genic sys­tem of the main linac cry­omod­ule. We fur­ther de­scribe the use of a Least Mean Square al­go­rithm in es­tab­lish­ing a sta­ble Ac­tive Mi­cro­phon­ics Com­pen­sa­tion sys­tem for op­er­a­tion of the main linac cav­i­ties. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF038  
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WEPMF042 A Computational Method for More Accurate Measurements of the Surface Resistance in SRF Cavities cavity, operation, niobium, radio-frequency 2458
 
  • J.T. Maniscalco, M. Liepe
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  The prin­ci­pal loss mech­a­nism for su­per­con­duct­ing RF cav­i­ties in nor­mal op­er­a­tion is Ohmic heat­ing due to the mi­crowave sur­face re­sis­tance in the su­per­con­duct­ing sur­face. The typ­i­cal method for cal­cu­lat­ing this field-de­pen­dent sur­face re­sis­tance Rs(H) from RF mea­sure­ments of qual­ity fac­tor Q0 im­plic­itly re­turns a weighted av­er­age of Rs over the sur­face as a func­tion of peak sur­face mag­netic field H, not the true value of Rs as a func­tion of the local mag­ni­tude of H. In this work we pre­sent a com­pu­ta­tional method to con­vert a mea­sured Q0 vs. Hpeak to a more ac­cu­rate Rs vs. Hlocal, given knowl­edge about cav­ity geom­e­try and field dis­tri­b­u­tion.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF042  
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WEPMF044 Updates on the DC Field Dependence Cavity cavity, niobium, multipactoring, simulation 2465
 
  • J.T. Maniscalco, M. Liepe
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Work at Cor­nell has demon­strated good agree­ment be­tween a the­o­ret­i­cal model by A. Gure­vich of the anti-Q-slope (a field-de­pen­dent de­crease of the mi­crowave sur­face re­sis­tance) and ex­per­i­men­tal re­sults from im­pu­rity-doped nio­bium. As a corol­lary, the model pre­dicts that a strong DC mag­netic field ap­plied par­al­lel to the RF sur­face will pro­duce a sim­i­lar de­crease in sur­face re­sis­tance. In order to ex­plore this pre­dic­tion for many ma­te­ri­als, we have de­signed a new coax­ial cav­ity with a strong, uni­form DC field su­per­im­posed over a weak RF field on a re­mov­able and re­place­able nio­bium sam­ple. Here we pre­sent up­dates on the progress of this new cav­ity.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF044  
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WEPMF045 Performance of the Prototype SRF Half-Wave-Resonators Tested at Cornell for the RAON Project cavity, multipactoring, pick-up, radiation 2468
 
  • M. Ge, F. Furuta, T. Gruber, S.W. Hartman, M. Liepe, J.T. Maniscalco, T.I. O'Connell, P.J. Pamel, J. Sears, V. Veshcherevich
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • B.H. Choi, J. Joo, J.W. Kim, W.K. Kim, J. Lee, I. Shin
    IBS, Daejeon, Republic of Korea
  
  Two pro­to­type su­per­con­duct­ing half-wave-res­onator (162.5 MHz and β=0.12) for the RAON pro­ject have been suc­cess­fully tested at Cor­nell Uni­ver­sity. De­tailed ver­ti­cal per­for­mance test­ing in­cluded (1) test of the bare cav­ity with­out the he­lium tank, and (2) test of the dressed cav­ity with a he­lium tank. In this paper, we re­port on the de­vel­op­ment of the test in­fra­struc­ture, test re­sults, and per­for­mance data analy­sis, show­ing that the spec­i­fi­ca­tions for RAON were met.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF045  
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WEPMF046 Modeling of the Frequency and Field Dependence of the Surface Resistance of Impurity-Doped Niobium cavity, niobium, experiment, ECR 2471
 
  • J.T. Maniscalco, P.N. Koufalis, M. Liepe
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  The anti-Q-slope, a field-de­pen­dent de­crease in sur­face re­sis­tance ob­served in im­pu­rity-doped nio­bium, has been in­ves­ti­gated ex­ten­sively in 1.3 GHz cav­i­ties. New early re­search into this ef­fect has re­cently been per­formed at higher and lower fre­quen­cies, re­veal­ing an ad­di­tional de­pen­dence on fre­quency: the anti-Q-slope is stronger at higher fre­quen­cies and weaker at lower fre­quen­cies. Sev­eral mod­els have been pro­posed to ex­plain the anti-Q-slope, with vary­ing suc­cess in this new fre­quency-de­pen­dent regime. In this work, we an­a­lyze re­cent ex­per­i­men­tal data from a low-tem­per­a­ture-doped 1.3 GHz cav­ity and a high-tem­per­a­ture ni­tro­gen-doped 2.6 GHz cav­ity and dis­cuss the im­pli­ca­tions of these re­sults on the pro­posed mod­els.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF046  
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WEPMF047 Performance of Samples With Novel SRF Materials and Growth Techniques cavity, superconducting-RF, niobium, site 2475
 
  • T.E. Oseroff, M. Ge, M. Liepe, J.T. Maniscalco, R.D. Porter
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • S.R. McNeal
    Ultramet, Pacoima, California, USA
  • M.J. Sowa
    Veeco-CNT, Medford, USA
  
  Novel ma­te­ri­als are cur­rently being stud­ied in an at­tempt to push ac­cel­er­at­ing su­per­con­duct­ing RF cav­i­ties to sup­port higher ac­cel­er­at­ing fields and to op­er­ate with lower power loss. Grow­ing lay­ers of these ma­te­ri­als of the qual­ity nec­es­sary has proven to be dif­fi­cult. In this work, we pre­sent the SRF per­for­mance of pla­nar sam­ples of the promis­ing ma­te­ri­als, NbN and Nb¬3Sn, grown using atomic layer de­po­si­tion (ALD) and chem­i­cal vapor de­po­si­tion (CVD) re­spec­tively. Re­sults are promis­ing.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF047  
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WEPMF050 Update on Nb3Sn Progress at Cornell University cavity, niobium, accelerating-gradient, site 2479
 
  • R.D. Porter, J. Ding, D.L. Hall, M. Liepe
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • T.A. Arias, P. Cueva, D.A. Muller, N. Sitaraman
    Cornell University, Ithaca, New York, USA
  
  Nio­bium-3 Tin (Nb3Sn) is the most promis­ing al­ter­na­tive ma­te­r­ial for SRF ac­cel­er­a­tor cav­i­ties. The ma­te­r­ial can achieve higher qual­ity fac­tors, higher tem­per­a­ture op­er­a­tion and po­ten­tially higher ac­cel­er­at­ing gra­di­ents com­pared to con­ven­tional nio­bium. Cor­nell Uni­ver­sity has a lead­ing pro­gram to pro­duce 2 - 3 mi­crom­e­ter thick coat­ings of Nb3Sn on Nb for SRF ap­pli­ca­tions using vapor dif­fu­sion. This pro­gram has been the first to pro­duce qual­ity fac­tors higher than achiev­able with con­ven­tional Nb at us­able ac­cel­er­at­ing gra­di­ents. Here we pre­sent an up­date on progress at Cor­nell Uni­ver­sity, in­clud­ing stud­ies of the for­ma­tion of the Nb3Sn layer, den­sity func­tional the­ory cal­cu­la­tions of Nb3Sn growth, and de­signs for a sam­ple host cav­ity for mea­sur­ing the quench field of Nb3Sn.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF050  
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WEPMK008 In-Depth Analysis of the Vertical Test Results of the Third-Harmonic Cavities for the E-XFEL Injector cavity, FEL, experiment, feedback 2644
 
  • M. Bertucci, A. Bignami, A. Bosotti, J.F. Chen, C.G. Maiano, P. Michelato, L. Monaco, R. Paparella, P. Pierini, D. Sertore
    INFN/LASA, Segrate (MI), Italy
  • C.G. Maiano, P. Pierini
    ESS, Lund, Sweden
  • C. Pagani
    Università degli Studi di Milano & INFN, Segrate, Italy
  
  The re­sults of the ver­ti­cal tests per­formed at LASA on the 3.9 GHz third-har­monic cav­i­ties for the E-XFEL in­jec­tor are here dis­cussed. Analy­sis of ex­per­i­men­tal data al­lows to con­firm that such high fre­quency cav­ity, pre­pared with stan­dard BCP treat­ment and 800°C an­neal­ing treat­ment, suf­fers an in­trin­sic per­for­mance lim­i­ta­tion at around 22 MV/m (@ 2 K) due to a global ther­mal dis­si­pa­tion mech­a­nism. A quan­ti­ta­tive in­ter­pre­ta­tion of the high field Q slope is also pre­sented ac­cord­ing to the lat­est the­o­ret­i­cal mod­els of field-de­pen­dent sur­face re­sis­tance.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMK008  
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WEPMK009 Status of the ESRF-EBS Magnets quadrupole, dipole, sextupole, octupole 2648
 
  • C. Benabderrahmane, J.C. Biasci, J-F. B. Bouteille, J. Chavanne, L. Eybert, L. Goirand, G. Le Bec, L. Lefebvre, S.M. Liuzzo, D. Martin, C. Penel, P. Raimondi, J.-L. Revol, F. Villar, S.M. White
    ESRF, Grenoble, France
  
  The ESRF-EBS (Ex­tremely Bril­liant Source) is an up­grade pro­ject planned at the Eu­ro­pean Syn­chro­tron Ra­di­a­tion Fa­cil­ity (ESRF) in the pe­riod 2015-2022. A new stor­age ring will be built, aim­ing to de­crease the hor­i­zon­tal emit­tance and to im­prove the bril­liance and co­her­ence of the X-ray beams. The lat­tice of the new stor­age ring re­lies on mag­nets with de­mand­ing spec­i­fi­ca­tions: dipoles with lon­gi­tu­di­nal gra­di­ent (field rang­ing from 0.17 T up to 0.67 T), strong quadrupoles (up to 90 T/m), com­bined func­tion di­pole-quadrupoles with high gra­di­ent (0.57 T and 37 T/m), strong sex­tupoles and oc­tupoles. The de­sign of these mag­nets is based on in­no­v­a­tive so­lu­tions; in par­tic­u­lar, the lon­gi­tu­di­nal gra­di­ent dipoles are per­ma­nent mag­nets and the com­bined di­pole-quadrupoles are sin­gle-sided de­vices. The lon­gi­tu­di­nal gra­di­ent dipoles have been as­sem­bled and mea­sured in house. The de­sign of the mag­nets, pro­duc­tion sta­tus and mag­netic mea­sure­ment re­sults will be pre­sented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMK009  
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WEPMK012 Update on Plasma Processing R&D for LCLS-II plasma, cavity, HOM, experiment 2656
 
  • P. Berrutti, A. Grassellino, T.N. Khabiboulline, M. Martinello
    Fermilab, Batavia, Illinois, USA
  • M. Doleans, S.-H. Kim, K.E. Tippey
    ORNL, Oak Ridge, Tennessee, USA
  • D. Gonnella, G. Lanza, M.C. Ross
    SLAC, Menlo Park, California, USA
  
  Funding: Fermi Research Alliance, LLC, under Contract DE-AC02-07CH11359 with the U.S. DOE
SRF cav­i­ties per­for­mance preser­va­tion is cru­cial, from ver­ti­cal test to ac­cel­er­a­tor op­er­a­tion. Field emis­sion is still one of the main prob­lems to over­come and plasma clean­ing has been proven suc­cess­ful by SNS, in clean­ing field emit­ters and in­creas­ing the work func­tion of Nb. A col­lab­o­ra­tion has been es­tab­lished be­tween FNAL, SLAC and ORNL with the pur­pose of ap­ply­ing plasma pro­cess­ing to LCLS-II cav­i­ties, in order to min­i­mize and over­come field emis­sion with­out af­fect­ing the high Q of N-doped cav­i­ties. The recipe will fol­low the neon-oxy­gen ac­tive plasma adopted at SNS, al­low­ing in-situ pro­cess­ing of cav­i­ties and cry­omod­ules from hy­dro­car­bon con­t­a­m­i­nants. A novel method for plasma ig­ni­tion has been de­vel­oped at FNAL: a plasma glow dis­charge is ig­nited using high order modes to over­come lim­i­ta­tions im­posed by the fun­da­men­tal power cou­pler. The re­sults of ex­per­i­ments on 9-cell LCLS-II cav­ity are pre­sented, along with plasma ig­ni­tion stud­ies. In ad­di­tion the RF sys­tem is shown and N-doped Nb sam­ples stud­ies are dis­cussed. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMK012  
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WEPMK014 A New Design for the Hilumi Radio-Frequency Dipole Bare Cavity cavity, niobium, GUI, resonance 2659
 
  • M. Parise, P. Berrutti, L. Ristori
    Fermilab, Batavia, Illinois, USA
  
  Crab­bing cav­i­ties are one of the tech­no­log­i­cal land­mark that will allow the LHC to op­ti­mize its per-for­mance and max­i­mize its in­te­grated lu­mi­nos­ity by al­low­ing a head-on col­li­sion be­tween the bunches de­spite the non-zero cross­ing angle. A total of 8 crab cav­i­ties will be in­stalled in the in­ter­ac­tion re­gion of each of the two ex­per­i­ments, ATLAS and CMS. In the last years, the two types of crab cav­i­ties were de-signed, built and tested under the US-LARP R&D pro-gram. Hor­i­zon­tal crab­bing is ob­tained with a ra­dio-fre­quency di­pole cav­ity (RFD) de­signed by Old Do-min­ion Uni­ver­sity (ODU), SLAC and Fer­mi­lab (FNAL). In this paper a new me­chan­i­cal de­sign, that uses pas­sive stiff­en­ers, is pre­sented. This de­sign leads to a de­crease of the Lorentz Force De­tun­ing fre­quency shift, sat­isfy the re­quire­ments on pres­sure sen­si­tiv­ity, val­i­date the struc­tural in­tegrity and in­crease the tuner sen­si­tiv­ity and the max­i­mum elas­tic tun­ing range. Fur­ther­more, it will be pos­si­ble to greatly sim­plify the shape of the mag­netic shield and He­lium ves­sel with re­spect to the cur­rent de­sign.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMK014  
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WEPMK015 Optimization of Vertical Electro-Polishing Process: Experiments with Updated Cathode on Single-Cell Cavity and Performance Achieved in Vertical Test cavity, cathode, linac, superconductivity 2662
 
  • F. Éozénou, L. Maurice
    CEA/DSM/IRFU, France
  • P. Carbonnier, C. Madec, Th. Proslier, C. Servouin
    CEA/DRF/IRFU, Gif-sur-Yvette, France
  • V. Chouhan, Y.I. Ida, K.N. Nii, T.Y. Yamaguchi
    MGH, Hyogo-ken, Japan
  • H. Hayano, S. Kato, H. Monjushiro, T. Saeki, M. Sawabe
    KEK, Ibaraki, Japan
  
  Marui Gal­va­niz­ing Co.​Ltd., and CEA have been study­ing Ver­ti­cal Elec­tro-Pol­ish­ing (VEP) on Nb sin­gle-cell ac­cel­er­at­ing su­per­con­duct­ing ac­cel­er­a­tor cav­ity with the goal of mass-pro­duc­tion and cost-re­duc­tion, in col­lab­o­ra­tion with KEK within TYL-FJPPL Par­ti­cle Physics Lab­o­ra­tory. Marui has in­vented and patented a ro­ta­tive cath­ode called ‘i-Ninja'. The ver­sion 5 has been tested for the first time in Eu­rope at CEA Saclay. The four wings of the cath­ode re­move ef­fi­ciently, bub­bles of hy­dro­gen, and the cho­sen pa­ra­me­ters make it pos­si­ble to achieve bet­ter sur­face and uni­form ma­te­r­ial re­moval com­pared to VEP with a fixed cath­ode. The ef­fect of the tem­per­a­ture of the cav­ity walls on cur­rent os­cil­la­tions has been pre­cisely stud­ied. Two sin­gle-cell cav­i­ties have been elec­tro-pol­ished and tested at 2 K in ver­ti­cal cryo­stat and the re­sults will be pre­sented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMK015  
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WEPMK016 New Insight on Nitrogen Infusion Revealed by Successive Nanometric Material Removal cavity, accelerating-gradient, factory, niobium 2665
 
  • M. Checchin, A. Grassellino, M. Martinello, O.S. Melnychuk, S. Posen, A.S. Romanenko, D.A. Sergatskov
    Fermilab, Batavia, Illinois, USA
  
  In this study we pre­sent new in­sight on low tem­per­a­ture ni­tro­gen in­fu­sion on bulk nio­bium su­per­con­duct­ing ra­dio-fre­quency (SRF) cav­i­ties. Ni­tro­gen in­fu­sion is a ther­mal treat­ment re­cently dis­cov­ered at Fer­mi­lab that al­lows to reach high ac­cel­er­at­ing gra­di­ents, of the order of 45MV/m, with high Q-fac­tors, of the order of 2 · 1010. De­tailed depth de­pen­dent RF stud­ies (by means of sub­se­quent HF rinses) and com­par­ison­with SIMS re­sults pin­pointed in­ter­sti­tial ni­tro­gen as the re­spon­si­ble for the im­proved per­for­mance and un­cov­ered the ex­ten­sion of its pro­file in­side the ma­te­r­ial.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMK016  
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WEPML003 Precision Q0 Measurement of an SRF Cavity with a Digital RF Techniques cavity, coupling, impedance, GUI 2674
 
  • J.P. Holzbauer, B.M. Hanna, Y.M. Pischalnikov, W. Schappert, D.A. Sergatskov, A.I. Sukhanov
    Fermilab, Batavia, Illinois, USA
  
  Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
Di­rect mea­sure­ment of the qual­ity fac­tor of SRF cav­ity using tra­di­tional RF tech­niques is es­sen­tial for cav­ity pro­duc­tion and de­vel­op­ment. Sys­tem­atic ef­fects of the mea­sure­ment can con­tribute sig­nif­i­cant amounts of error to these mea­sure­ments if not ac­counted for. This paper will pre­sent mea­sure­ments taken at Fer­mi­lab using a dig­i­tal RF sys­tem to char­ac­ter­ize and cor­rect for these sys­tem­atic ef­fects and di­rectly mea­sure the qual­ity fac­tor ver­sus gra­di­ent curve for a sin­gle spoke res­onator in the Spoke Test Cryo­stat at Fer­mi­lab. These mea­sure­ments will be com­pared to tra­di­tional calori­met­ric mea­sure­ments, and a dis­cus­sion of im­prov­ing/ex­tend­ing these tech­niques to other test­ing sit­u­a­tions will be in­cluded. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML003  
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WEPML004 Production Tuner Testing for LCLS-II Cryomodule Production cavity, cryomodule, LLRF, interface 2678
 
  • J.P. Holzbauer, Y.M. Pischalnikov, W. Schappert, J.C. Yun
    Fermilab, Batavia, Illinois, USA
  • C. Contreras-Martinez
    FRIB, East Lansing, USA
  
  Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
LCLS-II 1.3 GHz cry­omod­ule pro­duc­tion is well un­der­way at Fer­mi­lab. Sev­eral dozen cav­ity/tuner sys­tems have been tested, in­clud­ing tun­ing to 1.3 GHz, cold land­ing fre­quency, range/sen­si­tiv­ity of the slow tuner, and range/sen­si­tiv­ity of the fast tuner. All this test­ing in­for­ma­tion as well as lessons learned from tuner in­stal­la­tion will be pre­sented. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML004  
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WEPML005 Testing of SSR1 Production Tuner for PIP-II cavity, linac, niobium, cryomodule 2681
 
  • J.P. Holzbauer, D. Passarelli, Y.M. Pischalnikov
    Fermilab, Batavia, Illinois, USA
  
  Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
The PIP-II pro­ject at Fer­mi­lab is a pro­ton dri­ver linac call­ing for the use of five dif­fer­ent, novel cav­ity geome­tries. Pro­to­typ­ing at Fer­mi­lab is in the ad­vanced stages for the low-beta sin­gle-spoke res­onator (SSR1) and as­so­ci­ated tech­nolo­gies. A pro­duc­tion tuner de­sign has been fab­ri­cated and tested, both warm and cold in the Spoke Test Cryo­stat (STC). This paper will pre­sent the de­tailed stud­ies on this tuner, in­clud­ing slow motor/piezo­elec­tric tuner range and hys­tere­sis as well as dy­namic me­chan­i­cal sys­tem char­ac­ter­i­za­tion. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML005  
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WEPML006 Modified Slow Tuner Design for Cavity 1 Inside LCLS II Cryomodules cavity, cryomodule, interface, simulation 2684
 
  • Y.M. Pischalnikov, T.T. Arkan, S. Cheban, J.P. Holzbauer, J.A. Kaluzny, Y.O. Orlov, J.C. Yun
    Fermilab, Batavia, Illinois, USA
  
  Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
Ini­tial LCLS-II cry­omod­ule test­ing at Fer­mi­lab showed mi­cro­phon­ics on the fur­thest up­stream cav­ity (num­ber 1) at least fac­tor 2 larger than on the rest of the cav­i­ties. Test­ing in­di­cated that this was a dif­fer­ence in the me­chan­i­cal sup­port of cav­ity 1, not a local acoustic source. Fur­ther in­ves­ti­ga­tion pointed to the up­stream beam-pipe of the cav­ity 1. The up­stream cav­ity flange has a solid spool piece con­nec­tion to the beam­line gate valve un­like the other cav­i­ties, which all con­nect through bel­lows. The gate valve's weight is sup­ported by slid­ing sys­tem (free in z-axis) con­nected to large di­am­e­ter He­lium gas re­turn pipe. The tuner de­sign was mod­i­fied to trans­form in­ter­face be­tween cav­ity#1 and gate valve. Arms of the tuner for cav­ity 1 were ex­tended and be­came the sup­port struc­ture for gate valve, elim­i­nat­ing the con­nec­tion to the he­lium re­turn pipe. Mod­i­fi­ca­tion of the tuner de­sign and re­sults in mi­cro­phon­ics mit­i­ga­tions will be pre­sented. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML006  
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WEPML008 Tuner Testing of a Dressed 3.9 GHz Cavity for LCLS-II at Fermilab cavity, operation, background, FEL 2690
 
  • J.P. Holzbauer, S. Aderhold, T.N. Khabiboulline, Y.M. Pischalnikov, W. Schappert, J.C. Yun
    Fermilab, Batavia, Illinois, USA
  • C. Contreras-Martinez
    FRIB, East Lansing, USA
  
  Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
Fer­mi­lab is re­spon­si­ble for the de­sign of the 3.9 GHz cry­omod­ule for LCLS-II. In­te­grated ac­cep­tance test­ing of a dressed 3.9 GHz cav­ity for the LCLS-II pro­ject has been done at the Fer­mi­lab Hor­i­zon­tal Test Stand. This test in­cluded a slim blade tuner (based on INFN & XFEL de­signs) with in­te­grated piezo­elec­tric fast/fine tuner. This paper will pre­sent re­sults of the me­chan­i­cal setup, cold test­ing, and cold func­tion of this tuner in­clud­ing fast and slow tuner range, sen­si­tiv­ity, and hys­tere­sis. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML008  
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WEPML010 Operation Regime Analysis of Conduction Cooled Cavities Through Multi-Physics Simulation cavity, operation, simulation, niobium 2697
 
  • R.A. Kostin, R. Dhuley, M.G. Geelhoed, R.D. Kephart, T.K. Kroc, O.V. Prokofiev, J.C.T. Thangaraj
    Fermilab, Batavia, Illinois, USA
  • A. Kanareykin
    Euclid TechLabs, LLC, Solon, Ohio, USA
  
  Funding: Department of Energy
Eu­clid Tech­labs in col­lab­o­ra­tion with Fer­mi­lab IARC (Batavia, IL) is de­vel­op­ing in­dus­trial su­per­con­duct­ing 10MeV elec­tron linac. Con­duc­tion cool­ing is used for cool­ing in­stead of liq­uid he­lium bath to sim­plify linac main­te­nance. The cav­ity linked to com­mer­cially avail­able cryo-cooler cold head through highly con­duc­tive alu­minium strips. How­ever, this so­lu­tion raises a prob­lem of con­tact ther­mal re­sis­tance. This paper shows some re­sults of Com­sol mul­ty­physics sim­u­la­tions of the cav­ity cool­ing by AL strips. Some in­sight was ob­tained on the ac­cept­able range of con­tact re­sis­tance. Op­er­a­tion regimes were ob­tained at dif­fer­ent ac­cel­er­at­ing gra­di­ents and cav­ity tem­per­a­tures. The re­sults of sim­u­la­tion are pre­sented and dis­cussed. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML010  
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WEPML013 Anti-Q-slope enhancement in high-frequency niobium cavities cavity, ECR, niobium, experiment 2707
 
  • M. Martinello, S. Aderhold, S.K. Chandrasekaran, M. Checchin, A. Grassellino, O.S. Melnychuk, S. Posen, A.S. Romanenko, D.A. Sergatskov
    Fermilab, Batavia, Illinois, USA
  
  N-doped 1.3 GHz nio­bium cav­i­ties showed for the first time the so-called anti-Q-slope, i.e. the in­creas­ing of the Q-fac­tor as a func­tion of the ac­cel­er­at­ing field. It was ver­i­fied that the anti-Q-slope is con­se­quence of the de­creas­ing of the tem­per­a­ture-de­pen­dent com­po­nent of the sur­face re­sis­tance as a func­tion of the field. This trend is op­po­site com­pared to the in­creas­ing of the sur­face re­sis­tance pre­vi­ously ob­served in 1.3 GHz stan­dard (EP, BCP, 120 C baked) nio­bium cav­i­ties. The ef­fect of the dif­fer­ent state-of-the-art sur­face treat­ments on the field de­pen­dence of the sur­face re­sis­tance is stud­ied for 650 MHz, 1.3 GHz, 2.6 GHz and 3.9 Ghz cav­i­ties. This pro­ceed­ing shows that the field de­pen­dence of the tem­per­a­ture-de­pen­dent com­po­nent of the sur­face re­sis­tance has a strong fre­quency de­pen­dence and that the anti-Q-slope may ap­pear even in clean nio­bium cav­i­ties if the res­o­nant fre­quency is high enough, sug­gest­ing new routes to­ward the un­der­stand­ing of the anti-Q-slope ef­fect.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML013  
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WEPML016 Development of Nb3Sn Coatings for Superconducting RF Cavities at Fermilab cavity, factory, superconductivity, network 2718
 
  • S. Posen, S.K. Chandrasekaran, O.S. Melnychuk, D.A. Sergatskov, B. Tennis, Y. Trenikhina
    Fermilab, Batavia, Illinois, USA
  • J. Lee
    NU, Evanston, Illinois, USA
  
  Nb3Sn films are a promis­ing al­ter­na­tive ma­te­r­ial for su-per­con­duct­ing RF cav­i­ties, with proven high qual­ity fac­tors at medium fields and pre­dic­tions for in­creased su­per­heat­ing field as well. In this con­tri­bu­tion, we de-scribe the lat­est re­sults from the Fer­mi­lab Nb3Sn SRF pro­gram. Early ex­per­i­ments have been fo­cused on sin­gle cell 1.3 GHz cav­i­ties. We briefly re­view ef­forts to bring the pa­ra­me­ters used in the coat­ing process into a range where they pro­duce uni­form sur­faces with­out re­gions show­ing signs of ex­cess tin or thin/un­coated areas. We then pre­sent the lat­est cav­ity re­sults, after mod­i­fi­ca­tions to the coat­ing recipe based on feed­back from film ap­pear-ance and RF per­for­mance. These re­sults show high Q0 at medium fields and a max­i­mum field of ~18 MV/m.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML016  
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WEPML040 Further Tests on the Final State of the SC 325 MHz CH-Cavity and Coupler Test Bench Update cavity, linac, heavy-ion, framework 2783
 
  • M. Busch, M. Basten, J. List, P. Müller, H. Podlech, M. Schwarz
    IAP, Frankfurt am Main, Germany
  • W.A. Barth, J. List
    GSI, Darmstadt, Germany
  • W.A. Barth
    HIM, Mainz, Germany
  • W.A. Barth
    MEPhI, Moscow, Russia
  
  Funding: Work supported by BMBF Contr. No. 05P15RFBA
At the In­sti­tute for Ap­plied Physics, Goethe-Uni­ver­sity Frank­furt, a sc 325 MHz CH-cav­ity has been de­vel­oped and suc­cess­fully tested up to 14.1 mV/m and has now reached the final pro­duc­tion stage with the he­lium ves­sel welded to the frontal joints of the cav­ity and final pro­cess­ing steps have been per­formed. Fur­ther tests in a ver­ti­cal and hor­i­zon­tal en­vi­ron­ment are being pre­pared for in­ten­sive stud­ies. This cav­ity is a pro­to­type for en­vis­aged beam tests with a pulsed ion beam at 11.4 AMeV. In this con­tri­bu­tion the re­sults of the per­formed RF tests are being pre­sented. Fur­ther­more, first mea­sure­ments of the re­cently in­stalled 217 MHz cou­pler test bench are shown. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML040  
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WEPML045 Infrastructure for Superconducting CH-Cavity Preparation at HIM cavity, linac, vacuum, heavy-ion 2796
 
  • T. Kürzeder, K. Aulenbacher, W.A. Barth, F.D. Dziuba, V. Gettmann, M. Miski-Oglu, E. Riehn
    HIM, Mainz, Germany
  • K. Aulenbacher, R.G. Heine, T. Stengler
    IKP, Mainz, Germany
  • W.A. Barth, S. Yaramyshev
    GSI, Darmstadt, Germany
  • F. Hug
    KPH, Mainz, Germany
  
  A su­per­con­duct­ing cw LINAC for heavy ions is cur­rently under de­vel­op­ment at GSI in Darm­stadt and HIM in Mainz. This Linac is based on 217 MHz multi­gap bulk nio­bium Cross­bar H-mode RF-cav­i­ties. In order to treat and pre­pare RF-cav­i­ties with such a com­plex geom­e­try a new clean­room fa­cil­ity has been al­ready built at the Helmholtz-In­sti­tut in Mainz. All tools and ma­chines in­side the clean­room can han­dle cav­i­ties with up to 800 mm in di­am­e­ter and with up to 1300 mm in length. In its ISO-class 6 and 4 zones, re­spec­tively it fea­tures a large ul­tra­sonic and con­duc­tance rins­ing bath, a high pres­sure rins­ing (HPR) cab­i­net and a vac­uum oven. The HPR cab­i­net has an in­side clear­ance of 1.4 m. The large cav­i­ties sit on a ro­tat­ing table, while the ris­ing wand moves ver­ti­cally up and down. Due to the cross­bar struc­ture of the RF-cav­i­ties the HPR de­vice al­lows for off axis-rins­ing in their quad­rants. For RF test­ing a 52 m² (4 m x 13 m) con­crete shielded area with suf­fi­cient liq­uid he­lium and ni­tro­gen sup­ply is lo­cated next to the clean­room and the cryo-mod­ule as­sem­bly area. We will re­port on the new SRF in­fra­struc­ture in Mainz and the com­mis­sion­ing of the new high pres­sure rins­ing cab­i­net.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML045  
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WEPML047 Study on RF Coupler Kicks of SRF Cavities in the BESSY VSR Module cavity, storage-ring, HOM, GUI 2804
 
  • A.V. Tsakanian, T. Mertens
    Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), Berlin, Germany
  • H.-W. Glock, J. Knobloch, M. Ries, A.V. Vélez
    HZB, Berlin, Germany
  
  The BESSY VSR up­grade of the BESSY II light source rep­re­sents a novel ap­proach to si­mul­ta­ne­ously store long (ca. 15ps) and short (ca. 1.7ps) bunches in the stor­age ring with the stan­dard user op­tics. This chal­leng­ing goal re­quires in­stal­la­tion of four new SRF multi-cell cav­i­ties (2x1.5GHz and 2x1.75GHz) equipped with strong wave­guide HOM dampers en­sur­ing tol­er­a­ble beam cou­pling im­ped­ance, nec­es­sary for sta­ble op­er­a­tion. These cav­i­ties will op­er­ate at high 20MV/m in CW mode and at the zero-cross­ing phase ac­cord­ing to the ac­cel­er­at­ing volt­age. Con­se­quently the trans­verse volt­ages will be max­i­mum and can im­pact the trans­verse beam dy­nam­ics. The asym­met­ric char­ac­ter of those trans­verse kicks are caused by cav­ity fun­da­men­tal power cou­plers (FPC) with strong mono­pole terms, in­tro­duc­ing trans­verse kick to on-axis par­ti­cles. Dif­fer­ent FPC ori­en­ta­tions were an­a­lyzed to op­ti­mize the net cou­pler kick from the four cav­ity chain. The cou­pler kick strength of each cav­ity is es­ti­mated tak­ing into ac­count ac­cel­er­at­ing mode am­pli­tudes and phases re­quired for op­er­a­tion in VSR mode.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML047  
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WEPML048 HOM Power Levels in the BESSY VSR Cold String HOM, cavity, simulation, GUI 2808
 
  • A.V. Tsakanian, T. Flisgen
    Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), Berlin, Germany
  • H.-W. Glock, J. Knobloch, A.V. Vélez
    HZB, Berlin, Germany
  
  The BESSY VSR up­grade of the BESSY II light source rep­re­sents a novel ap­proach to si­mul­ta­ne­ously store long (ca. 15ps) and short (ca. 1.7ps) bunches in the stor­age ring. This chal­leng­ing goal re­quires in­stal­la­tion of four new SRF cav­i­ties (2x1.5 GHz and 2x1.75 GHz) in one mod­ule for in­stal­la­tion in a sin­gle straight. These cav­i­ties are equipped with strong wave­guide HOM dampers nec­es­sary for sta­ble op­er­a­tion. The ex­pected HOM power and spec­trum has been an­a­lyzed for the com­plete cold string. The cold string is a com­bi­na­tion of var­i­ous el­e­ments such as SRF cav­i­ties, bel­lows with and with­out shield­ing, warm HOM beampipe ab­sorbers and UHV pump­ing domes. The pre­sented study is per­formed for var­i­ous BESSY VSR bunch fill­ing pat­terns with 300 mA beam cur­rent. The con­tri­bu­tion of each com­po­nent to the total HOM power is pre­sented. In ad­di­tion the op­ti­miza­tion of dif­fer­ent cav­ity arrange­ments in the mod­ule is per­formed in order to reach the op­ti­mal op­er­a­tion con­di­tions with equally dis­trib­uted power lev­els along the string and tol­er­a­ble beam cou­pling im­ped­ance.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML048  
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WEPML049 The Challenge to Measure nΩ Surface Resistance on SRF Samples quadrupole, pick-up, cavity, simulation 2812
 
  • S. Keckert, T. Junginger, J. Knobloch, O. Kugeler
    HZB, Berlin, Germany
  • T. Junginger
    Lancaster University, Lancaster, United Kingdom
  
  Sys­tem­atic re­search on fun­da­men­tal lim­its of su­per­con­duct­ing ma­te­ri­als for SRF ap­pli­ca­tions and their in­trin­sic ma­te­r­ial prop­er­ties rel­e­vant for use in an ac­cel­er­a­tor re­quires stud­ies in a wide pa­ra­me­ter space of tem­per­a­ture, RF field and fre­quency. The Quadru­pole Res­onator at HZB en­ables pre­ci­sion mea­sure­ments on pla­nar sam­ples at tem­per­a­tures of 1.8 K to >20 K, RF fields of up to 120 mT, and fre­quen­cies of 420 MHz, 850 MHz and 1285 MHz. In the past years the ca­pa­bil­i­ties of the setup were stud­ied in­ten­sively and de­vel­oped fur­ther. Sources of sys­tem­atic er­rors, such as mi­cro­phon­ics or mis­align­ment have been iden­ti­fied and elim­i­nated. In this con­tri­bu­tion the cur­rent sta­tus of the QPR and its sys­tem­atic lim­i­ta­tions are dis­cussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML049  
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WEPML053 Availability of the TiN Coating-Free Ceramic in the STF-type Power Coupler for ILC electron, vacuum, cryomodule, GUI 2819
 
  • Y. Yamamoto, E. Kako, T. Matsumoto, S. Michizono, A. Yamamoto
    KEK, Ibaraki, Japan
  • M. Irikura, M. Ishibashi, H. Yasutake
    Toshiba Electron Tubes & Devices Co., Ltd (TETD), Tochigi, Japan
  • C. Julie, E. Montesinos
    CERN, Geneva, Switzerland
  
  In the Su­per­con­duct­ing RF Test Fa­cil­ity (STF) in KEK, the re­search and de­vel­op­ment for the power cou­pler with the TiN coat­ing-free ce­ramic has been done from 2014. In 2016, the high power test at the test bench was stopped due to the worse vac­uum level by the un­usual heat­ing around the RF win­dow with the TiN coat­ing-free ce­ramic and the coax­ial ta­pered sec­tion, which was caused by the enor­mous emis­sion of the sec­ondary elec­trons from the ce­ramic. And, the sit­u­a­tion was never also changed by the ul­tra­pure water rins­ing for the power cou­plers sev­eral times. How­ever, in 2017, the ul­tra­sonic rins­ing was done for the power cou­plers for the first time by the col­lab­o­ra­tion be­tween KEK and TETD. After that, the sit­u­a­tion was dras­ti­cally im­proved, and the sec­ondary elec­tron emis­sion al­most dis­ap­peared even in the higher RF duty. This shows that the TiN coat­ing-free ce­ramic is the prospec­tive item for the cost re­duc­tion in ILC. In this re­port, the re­cent re­sult for the power cou­pler with the TiN coat­ing-free ce­ramic will be pre­sented in de­tailed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML053  
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WEPML067 Second Sound Quench Detection on Superconducting Cavities cavity, detector, site, superconducting-cavity 2843
 
  • Z.C. Liu, S. Bai, J. Gao, F.S. He, H.Y. Lin, P. Zhang
    IHEP, Beijing, People's Republic of China
  
  Sec­ond sound is an ef­fec­tive way to de­tect the quench po­si­tion on su­per­con­duct­ing cav­ity. A sec­ond sound quench site de­tec­tion sys­tem is under de­vel­op­ing for the PAPS. High gra­di­ent is very im­por­tant for su­per­con­duct­ing cav­ity, how­ever it may be lim­ited by quench on the cav­ity high field re­gion. Quench can be caused by var­i­ous rea­sons. To lo­cate the po­si­tion is the key to re­veal the mys­ter­ies of quench. Now we are de­vel­op­ing the quench po­si­tion de­tec­tion sys­tem by RTD sen­sors such as Cer­nox and OST sen­sors.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML067  
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WEPML078 Development of a Superconducting Double-Spoke Cavity at IMP cavity, accelerating-gradient, ion-source, niobium 2869
 
  • T.C. Jiang, H. Guo, Y. He, C.L. Li, L.B. Liu, T. Tan, P.R. Xiong, Z.M. You, W.M. Yue, S.H. Zhang, S.X. Zhang
    IMP/CAS, Lanzhou, People's Republic of China
  
  Su­per­con­duct­ing multi-spoke cav­i­ties are well-known op­tional choice for ac­cel­er­a­tion of heavy ions in medium ve­loc­ity regimes. The paper de­scribes the de­sign, fab­ri­ca­tion and test re­sults of the su­per­con­duct­ing dou­ble-spoke cav­ity de­vel­oped at IMP. After Buffered Chem­i­cal Pol­ish­ing and High pres­sure Rins­ing, one cav­ity has un­der­gone high gra­di­ent RF test­ing at 4 K in the Ver­ti­cal Test Stand. We pre­sent mea­sure­ments of the qual­ity fac­tor as a func­tion of ac­cel­er­at­ing field and max­i­mum field on the sur­face. Ac­cel­er­at­ing gra­di­ent of more than 15 MV/m is reached with peak elec­tric field of 61 MV/m, and peak mag­netic field of 118 mT.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML078  
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THXGBD3 Status of the ESRF-Extremely Brilliant Source Project vacuum, operation, injection, dipole 2882
 
  • J.-L. Revol, C. Benabderrahmane, P. Berkvens, J.C. Biasci, J-F. B. Bouteille, T. Brochard, N. Carmignani, J.M. Chaize, J. Chavanne, F. Cianciosi, A. D'Elia, R.D. Dimper, M. Dubrulle, D. Einfeld, F. Ewald, L. Eybert, G. Gautier, L. Goirand, L. Hardy, J. Jacob, B. Joly, M.L. Langlois, G. Le Bec, I. Leconte, S.M. Liuzzo, C. Maccarrone, T.R. Mairs, T. Marchial, H.P. Marques, D. Martin, J.M. Mercier, A. Meunier, M. Morati, J. Pasquaud, T.P. Perron, E. Plouviez, E. Rabeuf, P. Raimondi, P. Renaud, B. Roche, K.B. Scheidt, V. Serrière, P. Van Vaerenbergh, R. Versteegen, S.M. White
    ESRF, Grenoble, France
  
  The ESRF - the Eu­ro­pean Syn­chro­tron Ra­di­a­tion Fa­cil­ity - is a user fa­cil­ity in Greno­ble, France, and the source of in­tense high-en­ergy (6 GeV) X-rays. In 2019, the ex­ist­ing stor­age ring will be re­moved and a new lat­tice will be in­stalled in its place, dra­mat­i­cally re­duc­ing the equi­lib­rium hor­i­zon­tal emit­tance. This 'fourth-gen­er­a­tion' syn­chro­tron will pro­duce an X-ray beam 100 times more bril­liant and co­her­ent than the ESRF source today. The Ex­tremely Bril­liant Source (EBS) pro­ject was launched in 2015 and is now well un­der­way, on track for its sched­uled com­ple­tion in 2020. The de­sign is com­pleted, the pro­cure­ment in full swing, the as­sem­bly has started, and crit­i­cal in­stal­la­tion ac­tiv­i­ties are being pre­pared. The cur­rent sta­tus, three years into the pro­ject, will be re­vealed, along with the ex­pected per­for­mance of the ac­cel­er­a­tor and the tech­ni­cal chal­lenges in­volved. This paper will focus on the im­ple­men­ta­tion of the pro­ject.  
slides icon Slides THXGBD3 [13.547 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THXGBD3  
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THPAF028 Multi-Objectives Genetic Algorithms (MOGA) Optimization of PETRA IV Scenarios lattice, injection, sextupole, dynamic-aperture 3015
 
  • X.N. Gavaldà, J. Keil, R. Wanzenberg
    DESY, Hamburg, Germany
  
  This paper re­ports the ap­pli­ca­tion of Multi-Ob­jec­tive Ge­netic Al­go­rithms (MOGA) to op­ti­mize the lin­ear and non­lin­ear beam dy­nam­ics of the dif­fer­ent PETRA IV sce­nar­ios to trans­form PETRA III stor­age ring in a dif­fracted lim­ited one. As it is well known, the dy­namic aper­ture and mo­men­tum ac­cep­tance of these kinds of lat­tices are dra­mat­i­cally re­duced due to the in­crease of the sex­tupoles strengths to com­pen­sate its strong fo­cus­ing. The re­duc­tion of the dy­namic aper­ture jeop­ar­dizes the cur­rent off-axis in­jec­tion sys­tem and lower beam life­times in­crease the beam in­sta­bil­i­ties and the ra­di­a­tion safety con­cerns of the stor­age ring. MOGA searches the best set­tings of quadrupoles and sex­tupoles in a multi-di­men­sional pa­ra­me­ter space tak­ing into ac­count the dy­namic prop­er­ties and the nat­ural emit­tance as ob­jec­tives at the level of ten pi­come­ters. The lat­tices stud­ied are the so-called 'Twist lat­tice' based in a phase space ex­change lat­tice, a so­lu­tion based in the ESRF-Hy­brid Multi-bend Achro­mat (HMA) de­sign and fi­nally the 'dou­ble 'I' lat­tice com­bin­ing a non-in­ter­leaved sex­tupoles cell with an ESRF-HMA cell.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF028  
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THPAF084 Impact of RF Coupler Kicks on Beam Dynamics in BESSY VSR cavity, simulation, kicker, lattice 3182
 
  • T. Mertens
    Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), Berlin, Germany
  • T. Atkinson, F. Glöckner, A. Jankowiak, M. Ries, A.V. Tsakanian
    HZB, Berlin, Germany
  
  The ex­pected BESSY II up­grade to BESSY VSR re­quires the in­stal­la­tion of a su­per­con­duct­ing RF sys­tem, con­sist­ing of four cav­i­ties. Two cav­i­ties will op­er­ate at 1.5 GHz and two at 1.75 GHz. Each of them is equipped with a Fun­da­men­tal Power Cou­pler and with Higher Order Mode (HOM) damp­ing wave­guide cou­plers. Ded­i­cated sim­u­la­tions of these cav­i­ties and cou­plers have shown that at the lo­ca­tion of the FPC the beam will see a trans­verse kick [*], per­turb­ing the closed orbit and af­fect­ing trans­verse beam dy­nam­ics. We pre­sent the re­sults of sim­u­la­tions and ex­per­i­ments of the im­pact on trans­verse beam dy­nam­ics of these cou­pler in­duced kicks for dif­fer­ent FPC ori­en­ta­tions.
[*] Study on RF Coupler Kicks of SRF Cavities in the BESSY VSR Module
A. Tsakanian#, H.-W. Glock, T. Mertens, M. Ries, A. Velez, J. Knobloch
IPAC18 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF084  
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THPAK076 Development and Benchmarking of the IMPACT-T Code rfq, linac, simulation, space-charge 3408
 
  • H.P. Li, M.J. Easton, Y.R. Lu, Z. Wang
    PKU, Beijing, People's Republic of China
  • J. Qiang
    LBNL, Berkeley, California, USA
  
  The multi-par­ti­cle track­ing code IM­PACT-T is widely used to cal­cu­late the par­ti­cle mo­tion in high in­ten­sity linacs. The code is a self-con­sis­tent three-di­men­sional beam dy­nam­ics sim­u­la­tion tool­box that uti­lizes the par­ti­cle-in-cell method in the time do­main. In the col­lab­o­ra­tion be­tween PKU and LBNL, an RFQ mod­ule was im­ple­mented to the IM­PACT-T code, which en­ables sim­u­la­tions of the ac­cel­er­a­tor front-end. In order to bench­mark the newly de­vel­oped mod­ule in the IM­PACT-T code, we have sim­u­lated the beam trans­port in Bei­jing Iso­tope Sep­a­ra­tion On-Line (BISOL) high in­ten­sity deuteron dri­ver linac. It con­sists of a 3 MeV RFQ and 40 MeV su­per­con­duct­ing HWR linac with five cry­omod­ules. After com­par­ing the sim­u­la­tion re­sults with PARMTEQM, TraceWin and Tou­tatis, we ob­tained a very good agree­ment, which rep­re­sents the val­i­da­tion of the new code.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK076  
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THPAL007 Upgrade of PIAVE Superconducting RFQs at INFN-Legnaro rfq, operation, cavity, superconducting-RF 3623
 
  • G. Bisoffi, E. Bissiato, D. Bortolato, F. Chiurlotto, T. Contran, E. Fagotti, A. Minarello, P. Modanese, E. Munaron, D. Scarpa
    INFN/LNL, Legnaro (PD), Italy
  • V. Andreev
    ITEP, Moscow, Russia
  • A. Bosotti, R. Paparella
    INFN/LASA, Segrate (MI), Italy
  • L.M.A. Ferreira
    CERN, Geneva, Switzerland
  • K. Kasprzak
    IFJ-PAN, Kraków, Poland
  • R.C. Pardo
    ANL, Argonne, Illinois, USA
  
  Su­per­con­duct­ing RFQs (SRFQs), the first SC RFQs ever made op­er­a­tional for users, have been op­er­ated on the PIAVE SC heavy ion linac in­jec­tor at INFN-Leg­naro since 2006. The struc­ture is split into two res­onators and is lim­ited to the ac­cel­er­at­ing RFQ sec­tions. The res­onators had never ex­ceeded 80% of the de­sign ac­cel­er­at­ing fields. In 2015, an up­grade plan started, aimed at in­creas­ing the ac­cel­er­at­ing fields, while im­prov­ing their slow and fast tun­ing sys­tems, re­pair­ing de­graded com­po­nents, im­ple-ment­ing a LASER align­ment method. The up­grade plan was suc­cess­fully con­cluded in sum­mer 2017. The res­ona-tors were kept sta­bly locked for days at a field larger than the nom­i­nal one. Even­tu­ally, a test beam was ac­cel­er­ated suc­cess­fully for 72 hours, with neg­li­gi­ble lock­ing is­sues. SRFQs en­tered once again rou­tine op­er­a­tion in De­cem­ber 2017. The new fea­tures will allow to ac­cel­er­ate heavy ions with an A/q value as high as 8.5 (ver­sus a for­mer max­i­mum A/q=7.5), al­low­ing op­er­a­tion of the very first ac­cel­er­ated ura­nium beams at INFN-LNL, after the re­lat-ed au­tho­riza­tions shall have been is­sued.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL007  
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THPAL012 Soft Chemical Polishing and Surface Analysis of Niobium Samples cavity, niobium, linac, operation 3641
 
  • J. Conrad, L. Alff, M. Arnold, S. Flege, R. Grewe, M. Major, N. Pietralla
    TU Darmstadt, Darmstadt, Germany
  • F. Hug
    IKP, Mainz, Germany
  
  Funding: Work supported by the German Federal Ministry for Education and Research (BMBF) under Grant No. 05H15RDRBA
The Su­per­con­duct­ing Darm­stadt Lin­ear Ac­cel­er­a­tor S-DALINAC uses twelve Nio­bium Cav­i­ties with a RRR of 280 which are op­er­ated at 2 K. The op­er­at­ing fre­quency is 3 GHz; the de­sign value of the ac­cel­er­at­ing gra­di­ent is 5 MV/m. To achieve the tar­get value of 3 x 10˄9 for Q0, dif­fer­ent sur­face prepa­ra­tion meth­ods were ap­plied and sys­tem­at­i­cally tested using a ver­ti­cal 2 K cryo­stat. A well-es­tab­lished tech­nique is the so called Darm­stadt Soft Chem­i­cal Pol­ish­ing, which con­sists of an ul­tra­sonic clean­ing of the cav­ity with ul­tra­pure water fol­lowed by ox­i­diz­ing the inner sur­face with ni­tric acid. After rins­ing with water the nio­bium oxide layer is re­moved with hy­dro­flu­o­ric acid in a sep­a­rate sec­ond step. Fi­nally the struc­ture is rinsed and then dried by a ni­tro­gen flow. Until now each cav­ity in op­er­a­tion was chem­i­cally treated with a proven record of suc­cess. In order to un­der­stand and to op­ti­mize the process on the nio­bium sur­face, sys­tem­atic tests with sam­ples were per­formed and an­a­lyzed using ma­te­r­ial sci­ence tech­niques like SEM, SIMS and EDX. We will re­port on the re­sults of our re­search and we will give a re­view on our ex­pe­ri­ences with var­ied chem­i­cal pro­ce­dures. 		 
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THPAL015 Evaluation of superconducting characteristics on the thin-film structure by NbN and Insulator coatings on pure Nb substrate cavity, embedded, radio-frequency, electromagnetic-fields 3653
 
  • R. Katayama, Y. Iwashita, H. Tongu
    Kyoto ICR, Uji, Kyoto, Japan
  • C.Z. Antoine
    CEA/IRFU, Gif-sur-Yvette, France
  • A. Four
    CEA/DRF/IRFU, Gif-sur-Yvette, France
  • H. Hayano, T. Kubo, T. Saeki
    KEK, Ibaraki, Japan
  • H. Ito
    Sokendai, Ibaraki, Japan
  • R. Ito, T. Nagata
    ULVAC, Inc, Chiba, Japan
  • H. Oikawa
    Utsunomiya University, Utsunomiya, Japan
  
  Funding: The work is supported by JSPS KAKENHI Grant Numbers JP17H04839, JP26600142 and the Collaborative Research Program of ICR Kyoto University (grant 2016-8, 2017-8, 2017-9).
In re­cent years, it is pointed out that the max­i­mum ac­cel­er­at­ing gra­di­ent of a su­per­con­duct­ing RF cav­ity can be pushed up by coat­ing the inner sur­face of cav­ity with a mul­ti­layer thin-film struc­ture that con­sists of al­ter­nate in­su­la­tor and su­per­con­duc­tive 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 start pen­e­trate into the first su­per­con­duc­tor layer. We made a sam­ple that has NbN/SiO2 thin-film struc­ture on pure Nb sub­strate by DC mag­netron sput­ter­ing method. In this paper, we will re­port the mea­sure­ment re­sults of ef­fec­tive Hc1 of the sam­ple by the third-har­monic volt­age method. 		 
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THPAL034 Dynamic Tuner Development for Medium β Superconducting Elliptical Cavities cavity, linac, operation, superconducting-RF 3709
 
  • C. Contreras-Martinez, P.N. Ostroumov
    FRIB, East Lansing, USA
  • E. Borissov, S. Cheban, Y.M. Pischalnikov, V.P. Yakovlev, J.C. Yun
    Fermilab, Batavia, Illinois, USA
  
  Funding: Work supported by U.S. DOE SCGSR program under contract number DE-SC0014664, Michigan State University, and Fermi Research Alliance under contract N. DEAC02-07CH11959 with the U.S. DOE
The Fa­cil­ity for Rare Iso­tope Beams (FRIB) is de­vel­op­ing a 5-cell 644 MHz βopt=0.65 el­lip­ti­cal cav­ity for a fu­ture linac en­ergy up­grade to 400 MeV/u for the heav­i­est ura­nium ions. Su­per­con­duct­ing el­lip­ti­cal cav­i­ties op­er­ated in con­tin­u­ous wave, such as the ones for FRIB, are prone to mi­cro­phon­ics which can ex­cite me­chan­i­cal modes of the cav­i­ties. It has been shown that the de­tun­ing due to mi­cro­phon­ics can be mit­i­gated with the use of piezo ac­tu­a­tors (fast tuner) as op­posed to the costly op­tion of in­creas­ing the input RF power. The FRIB slow/fast dy­namic tuner will be based on the Fer­mi­lab ex­pe­ri­ence with sim­i­lar tuners like those de­vel­oped for the linac co­her­ent light source (LCLS) II and pro­ton im­prove­ment plan (PIP) II. This paper will pre­sent the re­sults of tuner prop­er­ties on the bench. 		 
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THPAL036 Nb3Sn Thin Films for the Production of Higher Gradient SRF Cavities at Reduced Cost cavity, niobium, superconductivity, site 3716
 
  • S.A. Kahn, M.A. Cummings
    Muons, Inc, Illinois, USA
  • E.Z. Barzi, D. Turrioni
    Fermilab, Batavia, Illinois, USA
  • S. Falletta
    Politecnico di Torino, Torino, Italy
  • A. Kikuchi
    NIMS, Tsukuba, Ibaraki, Japan
  
  High gra­di­ent su­per­con­duct­ing cav­i­ties (SRF) will be needed for fu­ture ac­cel­er­a­tors. The higher gra­di­ent can achieve the high en­ergy with fewer cav­i­ties. How­ever the ac­cel­er­at­ing field of nio­bium cav­i­ties is lim­ited by the peak mag­netic field on the cav­ity sur­face. Cav­i­ties coated with Nb3Sn have a sig­nif­i­cantly larger Hc2 al­low­ing the cav­ity to achieve a larger gra­di­ent. Mea­sure­ments of Nb3Sn coated cav­i­ties have achieved about half the the­o­ret­i­cal pre­dicted gra­di­ent. It is pos­si­ble to im­prove Nb3Sn plated cav­ity per­for­mance.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL036  
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THPAL039 Improved Magnetron Stability and Reduced Noise in Efficient Transmitters for Superconducting Accelerators controls, cavity, feedback, experiment 3726
 
  • G.M. Kazakevich, R.P. Johnson
    Muons, Inc, Illinois, USA
  • V.A. Lebedev, V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
  
  State of the art high-cur­rent su­per­con­duct­ing ac­cel­er­a­tors re­quire ef­fi­cient RF sources with a fast dy­namic phase and power con­trol. This al­lows for com­pen­sa­tion of the phase and am­pli­tude de­vi­a­tions of the ac­cel­er­at­ing volt-age in the Su­per­con­duct­ing RF (SRF) cav­i­ties caused by mi­cro­phon­ics, etc. Ef­fi­cient mag­netron trans­mit­ters with fast phase and power con­trol are at­trac­tive RF sources for this ap­pli­ca­tion. They are more cost ef­fec­tive than tra­di­tional RF sources such as kly­strons, IOTs and solid-state am­pli­fiers used with large scale ac­cel­er­a­tor pro­jects. How­ever, un­like tra­di­tional RF sources, con­trolled mag­netrons op­er­ate as forced os­cil­la­tors. Study of the im­pact of the con­trol­ling sig­nal on mag­netron sta­bil­ity, noise and ef­fi­ciency is there­fore im­por­tant. This paper dis­cusses ex­per­i­ments with 2.45 GHz, 1 kW tubes and ver­i­fies our an­a­lyt­i­cal model which is based on the charge drift ap­prox­i­ma­tion.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL039  
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THPAL041 Power Coupler Design for the LUCRECE Project cavity, simulation, coupling, linac 3732
 
  • H. Guler, D. Auguste, J. Bonis, O. Bouras, M. El Khaldi, W. Kaabi, P. Lepercq
    LAL, Orsay, France
  
  The LU­CRECE pro­ject aims at de­vel­op­ing an el­e­men­tary RF sys­tem (cav­ity, power source, LLRF and con­trols) suit­able for con­tin­u­ous (CW) op­er­a­tion at 1.3 GHz. This ef­fort is made in the frame­work of the ad­vanced and com­pact FEL pro­ject LUNEX5 (free elec­tron Laser Using a New ac­cel­er­a­tor for the Ex­ploita­tion of X-ray ra­di­a­tion of 5th gen­er­a­tion), using su­per­con­duct­ing linac tech­nol­ogy for high rep­e­ti­tion rate and multi-user op­er­a­tion (www.​lunex5.​com). In this con­text, based on its large ex­pe­ri­ence on cou­pler de­sign and RF con­di­tion­ing, LAL Lab­o­ra­tory is in charge of the de­sign and the fab­ri­ca­tion of RF cou­plers that could op­er­ate at up to 15-20 kW in CW mode. For this pur­pose, geom­e­try based on COR­NELL 65kW CW cou­plers will me mod­i­fied to ful­fil the LCLS2 type cav­ity with the high nec­es­sary cou­pling level. Elec­tro­mag­netic sim­u­la­tions and op­ti­mi­sa­tion and as­so­ci­ated ther­mal heat­ing will be dis­cussed. Meth­ods to de­crease the ther­mal im­pact, and strat­egy for RF con­di­tion­ing will be con­sid­ered.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL041  
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THPAL045 Determination of the Electron Bunch Length With Third Harmonic Cavity for the Taiwan Photon Source cavity, operation, simulation, electron 3745
 
  • Z.K. Liu, F.Y. Chang, L.-H. Chang, M.H. Chang, S.W. Chang, L.J. Chen, F.-T. Chung, M.-C. Lin, C.H. Lo, Ch. Wang, M.-S. Yeh, T.-C. Yu
    NSRRC, Hsinchu, Taiwan
  
  The Tai­wan Pho­ton Source (TPS) is a mod­ern 3 GeV low emit­tance light source with RMS bunch lengths of about 3 mm at a beam cur­rent of 500 mA and op­er­at­ing gap volt­age of 3.2 MV. With a higher har­monic cav­ity, we could in­crease the Tou­schek life­time and lower the heat load of in-vac­uum un­du­la­tors by length­en­ing the bunch lengths. Pre­lim­i­nary stud­ies show that for full and uni-form fill pat­terns, the bunch lengths could be in­creased by a fac­tor of four. How­ever, this cal­cu­la­tion ig­nores phase tran­sient ef­fects and may over­es­ti­mate the ef­fect of har­monic cav­i­ties. A multi-bunch, multi-par­ti­cle track­ing method has been de­vel­oped to de­ter­mine the bunch lengths for non-uni­form fill pat­terns, which also takes phase tran­sient ef­fects into ac­count and the ex­pected max­i­mum bunch length­en­ing fac­tor for dif­fer­ent TPS op­er­a­tion con­di­tions are dis­cussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL045  
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THPAL065 Improving the Work Function of Nitrogen-Doped Niobium Surfaces for SRF Cavities by Plasma Processing plasma, cavity, niobium, accelerating-gradient 3802
 
  • K.E. Tippey, R. Afanador, M. Doleans, S.-H. Kim, J.D. Mammosser, C.J. McMahan
    ORNL, Oak Ridge, Tennessee, USA
  • M. Martinello
    Fermilab, Batavia, Illinois, USA
  
  Funding: DOE research grant FWP-ERKCSA2; DOE contract DE-AC05-00OR22725
Work func­tion and sur­face chemistries of SiC-pol­ished, elec­trop­o­l­ished, and ni­tro­gen-doped nio­bium coupons were an­a­lyzed be­fore and after plasma pro­cess­ing using a neon-oxy­gen gas mix­ture. These stud­ies rep­re­sent an ini­tial en­quiry into the fea­si­bil­ity of ap­ply­ing the plasma pro­cess­ing tech­nique de­signed at ORNL for the Spal­la­tion Neu­tron Source (SNS) to the ni­tro­gen-doped Nb cav­i­ties for the Co­her­ent Light Source II (LCLS-II). Work func­tion of all mea­sured sam­ples was in­creased after plasma pro­cess­ing, which in­di­cates the strong po­ten­tial of the plasma pro­cess­ing tech­nique as a tool for in­creas­ing the ac­cel­er­at­ing gra­di­ent of ni­tro­gen-doped cav­i­ties. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL065  
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THPAL076 Experimental Methods for the Assessment of NEG Pumps Working in Dust-Sensitive Environments vacuum, cavity, experiment, background 3828
 
  • T. Porcelli, E. Maccallini, P. Manini, M. Mura, M.F. Urbano
    SAES Getters S.p.A., Lainate, Italy
  
  NEG pumps have been widely adopted by many ac­cel­er­a­tor fa­cil­i­ties since decades. How­ever, their use in dust-sen­si­tive areas - such as su­per­con­duc­tive radio fre­quency (SRF) cav­i­ties - has al­ways been lim­ited by con­cerns about ac­ci­den­tal dust emis­sion, which could in­duce detri­men­tal field emis­sion. As fu­ture ma­chines will nec­es­sar­ily rely on highly-ef­fi­cient SRF cav­i­ties, able to sup­ply very high ac­cel­er­at­ing gra­di­ents, re­quire­ments in terms of par­ti­cle re­lease from vac­uum com­po­nents (e.g., pumps and valves) are be­com­ing more and more strin­gent. At the same time, achiev­ing sta­ble ul­tra-high vac­uum con­di­tions is cru­cial, as con­densed resid­ual gas might also be a po­ten­tial source of field emis­sion. At pre­sent, a uni­fied stan­dard pro­ce­dure to as­sess dust gen­er­a­tion and prop­a­ga­tion along a ma­chine is still miss­ing and dis­cus­sions are on­go­ing in the vac­uum com­mu­nity. Re­cent ex­per­i­men­tal mea­sure­ments demon­strated the com­pat­i­bil­ity of sin­tered NEG pumps with ul­tra-clean en­vi­ron­ments, due to their in­trin­sic very low dust re­lease. In par­al­lel, in-situ tests per­formed at dif­fer­ent ac­cel­er­a­tor fa­cil­i­ties showed ab­sence of dust con­t­a­m­i­na­tion from NEGs and no im­pact on cav­i­ties ef­fi­ciency.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL076  
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THPAL080 Parallel-Feed SRF Accelerator Structures cavity, coupling, simulation, impedance 3835
 
  • P.B. Welander, Z. Li, M.H. Nasr, S.G. Tantawi
    SLAC, Menlo Park, California, USA
  
  Funding: This work is supported by the Department of Energy, Laboratory Directed Research and Development program at SLAC National Accelerator Laboratory, under contract DE-AC02-76SF00515.
De­vel­op­ment of SRF ac­cel­er­a­tor tech­nol­ogy that en­ables both higher gra­di­ent and higher ef­fi­ciency is cru­cial for fu­ture ma­chines. While much of the re­cent R&D focus has been on ma­te­ri­als and sur­face sci­ence, our aim is to op­ti­mize the cav­ity geom­e­try to max­i­mize per­for­mance with cur­rent ma­te­ri­als. The re­cent demon­stra­tion of a highly ef­fi­cient par­al­lel-feed NCRF struc­ture at SLAC has served as a proof-of-con­cept. Ap­plied to SRF, such a struc­ture could dra­mat­i­cally re­duce power con­sump­tion while boost­ing the achiev­able gra­di­ent. In­stead of cou­pled el­lip­ti­cal cells, our struc­ture em­ploys iso­lated reen­trant cells. To feed RF power to the cav­i­ties, each cell is di­rectly cou­pled to an in­te­grated man­i­fold. The struc­ture is made in two parts, split along the beam axis, which are then joined. Such a struc­ture has been fab­ri­cated from bulk Cu and tested at SLAC - de­signed for X-band, it op­er­ates at a record gra­di­ent of 150 MV/m. Adapt­ing to SRF at 1.3 GHz and fab­ri­cat­ing from Nb, such a cav­ity could achieve more than 50% lower RF loss and 40% higher gra­di­ent com­pared to the TESLA cav­ity. We will de­scribe our sim­u­la­tions and pro­pose an ex­per­i­men­tal roadmap for demon­strat­ing this tech­nol­ogy. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL080  
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THPAL081 A 3 GHz SRF Reduced-beta Cavity for the S-DALINAC cavity, linac, operation, electron 3838
 
  • D.B. Bazyl, H. De Gersem, W.F.O. Müller
    TEMF, TU Darmstadt, Darmstadt, Germany
  • J. Enders, S. Weih
    TU Darmstadt, Darmstadt, Germany
  
  Funding: Work supported by DFG through GRK 2128
In order to re­duce the en­ergy spread and to be able to use a 200 keV spin-po­lar­ized elec­tron source, the ini­tial part of the in­jec­tor linac of the su­per­con­duct­ing Darm­stadt elec­tron lin­ear ac­cel­er­a­tor S-DALINAC needs to be up­graded. The de­ci­sions on the cav­ity type, num­ber of cells and value of geo­met­ric beta are mo­ti­vated. The main part of this work is ded­i­cated to the me­chan­i­cal de­sign of the cav­ity. A pre­cise eval­u­a­tion of the me­chan­i­cal char­ac­ter­is­tics of an SRF cav­ity is nec­es­sary dur­ing the de­sign stage. The de­pen­dence of the res­o­nant fre­quency of the fun­da­men­tal mode on ex­ter­nal me­chan­i­cal loads needs to be in­ves­ti­gated for de­vel­op­ing the tun­ing pro­ce­dures. The re­sults of the mul­ti­physics sim­u­la­tions and of the op­ti­miza­tion of the me­chan­i­cal de­sign are pre­sented. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL081  
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THPAL086 Superconducting Thin Film RF Measurements cavity, vacuum, niobium, operation 3856
 
  • P. Goudket, L. Bizel-Bizellot, L. Gurran, O.B. Malyshev, S.M. Pattalwar, R. Valizadeh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • G. Burt, L. Gurran
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • P. Goudket, T. Junginger, O.B. Malyshev, S.M. Pattalwar, R. Valizadeh
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • L. Gurran, T. Junginger
    Lancaster University, Lancaster, United Kingdom
  
  As part of an on­go­ing pro­gramme of SRF Thin Films de­vel­op­ment, a ra­diofre­quency (RF) cav­ity and cryo­stat ded­i­cated to the mea­sure­ment of su­per­con­duct­ing coat­ings at GHz fre­quen­cies was de­signed to eval­u­ate sur­face re­sis­tive losses on a flat sam­ple. The res­onator has now been used for mea­sure­ments on Thin Film sam­ples. Re­sults from a test on a sam­ple pre­vi­ously tested at Cor­nell Uni­ver­sity are pre­sented. In order to sim­plify the mea­sure­ments and achieve a faster turn­around, the ex­per­i­ment will be moved to a new cryo­stat fit­ted with a cry­ocooler. This will limit the mea­sure­ments to low power only, but will allow a much faster sort­ing of sam­ples to iden­tify those that would ben­e­fit from fur­ther in­ves­ti­ga­tion. A de­scrip­tion of the sys­tem and ini­tial re­sults will be pre­sented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL086  
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THPAL089 Design, Assembly and Commissioning of a New Cryogenic Facility for Complex Superconducting Thin Film Testing experiment, site, cavity, operation 3859
 
  • O.B. Malyshev, L. Bizel-Bizellot, K.D. Dumbell, P. Goudket, N. Pattalwar, S.M. Pattalwar, P. Pizzol, P.A. Smith, R. Valizadeh, S. Wilde
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • P. Pizzol
    The University of Liverpool, Liverpool, United Kingdom
  
  An on­go­ing study on the su­per­con­duct­ing thin films for fu­ture su­per­con­duct­ing RF cav­i­ties re­quires an in­tense test­ing of var­i­ous su­per­con­duct­ing prop­er­ties. We have de­signed, built and tested a new fa­cil­ity for com­plex su­per­con­duct­ing thin film test­ing that in­cludes: (1) RRR mea­sure­ment with and with­out mag­netic field, (2) pla­nar and (3) tubu­lar mag­netic field pen­e­tra­tion ex­per­i­ments, (4) a su­per­con­duct­ing coax­ial res­onator for bulk nio­bium and su­per­con­duct­ing thin film char­ac­ter­i­sa­tion. The sys­tem is based on a closed cycle re­frig­er­a­tor, elim­i­nat­ing the need for liq­uid he­lium, thus mak­ing it sim­ple and safe to op­er­ate. The de­tails of the de­sign and com­mis­sion­ing will be pre­sented at the con­fer­ence.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL089  
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THPAL092 Test Particle Monte Carlo Simulation of NEG Coated Narrow Tubular Samples vacuum, ECR, experiment, simulation 3862
 
  • O. Seify, A.N. Hannah, O.B. Malyshev, Sirvinskaite, R. Sirvinskaite, R. Valizadeh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • Sirvinskaite, R. Sirvinskaite
    Loughborough University, Loughborough, Leicestershire, United Kingdom
  
  The pump­ing prop­er­ties of the NEG coated vac­uum cham­bers play an im­por­tant role in the ef­fi­ciency of vac-uum sys­tem of ac­cel­er­a­tors. The stick­ing prob­a­bil­ity of the NEG films is one the most im­por­tant pa­ra­me­ters to char­ac­terise the pump­ing prop­er­ties of the NEG coated vac­uum cham­bers. In order to in­ves­ti­gate the NEG film stick­ing prob­a­bil­ity, Test Par­ti­cle Monte-Carlo (TPMC) mod­els were used. The mod­els were based on the de­sign of the in­stalled ex­per­i­men­tal setup in ASTeC Vac­uum Sci­ence group lab­o­ra­tory at Dares­bury Lab­o­ra­tory (DL). The re­sults of the sim­u­la­tions have been used for in­ter-pret­ing the re­sults of the mea­sure­ments in the ex­peri-men­tal setup.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL092  
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THPAL104 The Magnetic Field Measurement Systems for a Cryogenic Undulator and a Superconducting Undulator at SSRF cryogenics, undulator, GUI, vacuum 3878
 
  • H.F. Wang
    SSRF, Shanghai, People's Republic of China
  • M.F. Qian, W. Zhang, Q.G. Zhou
    SINAP, Shanghai, People's Republic of China
  
  Two cryo­genic per­ma­nent mag­net un­du­la­tors (CPMU) have been de­vel­oped and as­sem­bled into stor­age ring at SSRF，in order to reach larger mag­netic field and to pro­duce higher bril­liance in the hard X rays do­main. Low­er­ing the tem­per­a­ture of per­ma­nent mag­nets in­creases the mag­netic pro­duced field about by 15%. A set of mag­netic mea­sure­ment sys­tem and a suit­able mag­netic field op­ti­miza­tion method have been de­vel­oped. The de­sign of a mag­netic mea­sure­ment bench based on a Hall probe to per­form low tem­per­a­ture mea­sure­ment has been fin­ished. In ad­di­tion, a 50-pe­riod su­per­con­duct­ing un­du­la­tor pro­to­type with 16mm pe­riod length is also being de­vel­oped for more pho­tons with some spe­cific pho­ton char­ac­ter­is­tic. And a spe­cial hall probe sys­tem has been built in order to char­ac­ter­ize the mag­netic field dis­tri­b­u­tion of the SCU pro­to­type.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL104  
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THPAL105 Lower Critical Field Measurement System of Thin Film Superconductor controls, experiment, simulation, embedded 3882
 
  • H. Ito
    Sokendai, Ibaraki, Japan
  • C.Z. Antoine
    CEA/IRFU, Gif-sur-Yvette, France
  • A. Four
    CEA/DRF/IRFU, Gif-sur-Yvette, France
  • H. Hayano, T. Kubo, T. Saeki
    KEK, Ibaraki, Japan
  • R. Ito, T. Nagata
    ULVAC, Inc, Chiba, Japan
  • Y. Iwashita, R. Katayama, H. Tongu
    Kyoto ICR, Uji, Kyoto, Japan
  • H. Oikawa
    Utsunomiya University, Utsunomiya, Japan
  
  Funding: The work is supported by Japan Society for the Promotion of Science Grant-in-Aid for Young Scientist (A) No.17H04839.
Su­per­con­duct­ing thin film is the promis­ing tech­nol­ogy to in­crease the per­for­mance of SRF cav­i­ties. The lower crit­i­cal field Hc1, which is one of the im­por­tant phys­i­cal pa­ra­me­ters char­ac­ter­iz­ing a su­per­con­duct­ing ma­te­r­ial, will be en­hanced by coat­ing Nb with thin film su­per­con­duc­tor such as NbN. To in­ves­ti­gate the per­for­mance of thin film, we de­vel­oped the Hc1 mea­sure­ment sys­tem using the third har­monic re­sponse of ap­plied AC mag­netic field. The mea­sure­ment sys­tem con­sists of he­lium cryo­stat with two of GM re­frig­er­a­tors, sam­ple Cu stage, so­le­noid coil Cu mount, so­le­noid coil, tem­per­a­ture sen­sors, and liq­uid he­lium level meter. AC mag­netic field is pro­duced by a coil which is dri­ven by func­tion gen­er­a­tor and power am­pli­fier at around 1 kHz. In order to con­trol the tem­per­a­ture of the sam­ple stage and coil mount, the depth of ther­mal an­chors at­tached to the stage and the mount can be moved by the motor. By this tem­per­a­ture con­trol the sam­ple state can be eas­ily trans­ferred from Meiss­ner state to mixed state. So that the mea­sure­ment is re­peated for var­i­ous ap­plied mag­netic field, and the tran­si­tion curve can be made. In this re­port, per­for­mance of the mea­sure­ment sys­tem is de­scribed. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL105  
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THPAL120 Cryogenics Infrastructure at TRIUMF's Particle Accelerator Facilities cryogenics, TRIUMF, ISAC, operation 3925
 
  • A.N. Koveshnikov, Y. Bylinskii, G.W. Hodgson, D. Kishi, R.E. Laxdal, R.R. Nagimov, D. Yosifov
    TRIUMF, Vancouver, Canada
  
  Funding: TRIUMF receives federal funding via a contribution agreement with the National Research Council of Canada.
Cryo­genic in­fra­struc­ture is an in­dis­pens­able part of TRI­UMF ac­cel­er­a­tor fa­cil­i­ties. At the mo­ment TRI­UMF op­er­ates three he­lium cryo­genic sys­tems sup­port­ing op­er­a­tion of three major ac­cel­er­a­tor sys­tems: 520 MeV pro­ton cy­clotron, su­per­con­duc­tive ra­dio-fre­quency (SRF) heavy ion lin­ear ac­cel­er­a­tor at the Rare Iso­tope Beams (RIB) fa­cil­ity, and SRF elec­tron lin­ear ac­cel­er­a­tor (e-linac) at Ad­vanced Rare Iso­topE Lab­o­ra­tory (ARIEL). Ap­pli­ca­tions of cryo­genic ther­mal loads vary from cryo­genic ab­sorp­tion pump­ing of the cy­clotron vac­uum tank to cryo­genic cool­ing of su­per­con­duct­ing (SC) RF cav­i­ties of pro­duc­tion ac­cel­er­a­tors and sup­port of re­search and de­vel­op­ment at SRF de­part­ment. Wide range of pro­duc­tion tech­niques for cryo­genic re­frig­er­a­tion in­cludes he­lium re­frig­er­a­tors based on both pis­ton and tur­bine ex­pan­sion cold­boxes for both 4 K and 2 K tem­per­a­ture cryo­genic loads. This paper pre­sents the de­tails of TRI­UMF cryo­genic sys­tems as well as op­er­a­tional ex­pe­ri­ence of var­i­ous cryo­genic in­stal­la­tions. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL120  
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THPAL126 Nitrogen Bake-out Procedures at the Vertical High-Temperature UHV-Furnace of the S-DALINAC cavity, vacuum, niobium, linac 3937
 
  • R. Grewe, L. Alff, M. Arnold, J. Conrad, S. Flege, M. Major, N. Pietralla
    TU Darmstadt, Darmstadt, Germany
  • F. Hug
    IKP, Mainz, Germany
  
  Funding: Work supported by the Federal Ministry of Education and Research through grant No. 05H15RDRBA.
As the per­for­mance lim­its of bulk Nb srf cav­i­ties are reached, our re­search is fo­cused on ma­te­ri­als with su­pe­rior srf prop­er­ties like Nb3Sn and NbN. Re­search on NbN re­sulted in the "ni­tro­gen-dop­ing" process used for in­creas­ing the qual­ity fac­tors of srf cav­i­ties for the LCLS-II pro­ject. This process leads to delta-phase Nb-N, a phase with higher crit­i­cal sc pa­ra­me­ters than bulk Nb. This phase is formed at tem­per­a­tures of 800°C in ni­tro­gen at­mos­pheres of 10-2 mbar. Other crys­talline phases of NbN have even bet­ter sc pa­ra­me­ters. We con­cen­trate our re­search on ap­plic­a­bil­ity of delta-phase NbN for cav­i­ties. The delta-phase forms at tem­per­a­tures of above 1300°C, which is more than most of the fur­naces at ac­cel­er­a­tor fa­cilites are ca­pa­ble of. Since 2005 the In­sti­tute for Nu­clear Physics at the Tech­nis­che Uni­ver­sität Darm­stadt op­er­ates a high tem­per­a­ture vac­uum fur­nace which has been up­graded to allow tem­per­a­tures of up to 1750°C and bake­outs of nio­bium sam­ples and cav­i­ties in ni­tro­gen at­mos­pheres. We will re­port on the cur­rent sta­tus of our re­search on ni­tro­gen bake-out pro­ce­dures on Nb sam­ples. The sam­ples have been an­a­lyzed at the Ma­te­r­ial Sci­ence De­parte­ment with SIMS, REM and XRD. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL126  
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THPAL129 Magnetron Sputtering of Nb3Sn for SRF Cavities cavity, site, target, controls 3946
 
  • MNS. Sayeed, H. Elsayed-Ali
    ODU, Norfolk, Virginia, USA
  • G.V. Eremeev, M.J. Kelley, C.E. Reece
    JLab, Newport News, Virginia, USA
  • M.J. Kelley, U. Pudasaini
    The College of William and Mary, Williamsburg, Virginia, USA
  • M.J. Kelley
    Virginia Polytechnic Institute and State University, Blacksburg, USA
  
  Nb3Sn is a po­ten­tial can­di­date for sur­face ma­te­r­ial of SRF cav­i­ties since it can en­able the cav­ity to op­er­ate at higher tem­per­a­tures with high qual­ity fac­tor and at an in­creased ac­cel­er­at­ing gra­di­ent. Nb-Sn films were de­posited using mag­netron sput­ter­ing of in­di­vid­ual Nb and Sn tar­gets onto Nb and sap­phire sub­strates. The as-de­posited films were an­nealed at 1200 °C for 3 hours. The films were char­ac­ter­ized for their struc­ture by X-ray Dif­frac­tion (XRD), mor­phol­ogy by Field Emis­sion Scan­ning Elec­tron Mi­croscopy (FESEM), and com­po­si­tion by En­ergy Dis­per­sive X-ray Spec­troscopy (EDS) and Time of Flight Sec­ondary Ion Mass Spec­trom­e­try (ToF-SIMS). The sur­face re­sis­tiv­ity was mea­sured down to cryo­genic tem­per­a­ture to de­ter­mine the su­per­con­duct­ing tran­si­tion tem­per­a­ture and its width. The com­po­si­tion of the mul­ti­lay­ered films was con­trolled by vary­ing the thick­ness of the Nb and Sn lay­ers. The films showed crys­talline Nb3Sn phases with Tc up to 17.6 K.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL129  
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THPAL130 Effect of Deposition Temperature and Duration on Nb3Sn Diffusion Coating cavity, niobium, experiment, superconductivity 3950
 
  • U. Pudasaini, M.J. Kelley
    The College of William and Mary, Williamsburg, Virginia, USA
  • G.V. Eremeev, M.J. Kelley, C.E. Reece
    JLab, Newport News, Virginia, USA
  • M.J. Kelley, J. Tuggle
    Virginia Polytechnic Institute and State University, Blacksburg, USA
  
  Funding: Partially authored by Jefferson Science Associates under contract no. DE¬AC05¬06OR23177. Work at College of William & Mary supported by Office of High Energy Physics under grant SC0014475.
Nb3Sn is a po­ten­tial can­di­date to re­place Nb in SRF ac­cel­er­a­tor cav­i­ties to re­duce cost and ad­vance per­for-mance. Tin vapor dif­fu­sion is the pre­ferred tech­nique to re­al­ize such cav­i­ties by grow­ing a few mi­crons thick Nb3Sn coat­ing on the in­te­rior sur­face of the nio­bium cav­ity. The coat­ing process typ­i­cally uses tem­per­a­tures of 1100-1200 °C for 3-6 hours. It is im­por­tant to bet­ter un­der­stand the coat­ing process, and op­ti­mize the coat­ing pa­ra­me­ters to over­come the cur­rent lim­i­ta­tion on the per­for­mance of Nb3Sn coated SRF cav­i­ties. We in­vesti-gate Nb3Sn coat­ings pre­pared in the tem­per­a­ture range of 900-1200 °C and du­ra­tion of 3 - 12 hours using var­i­ous ma­te­r­ial char­ac­ter­i­za­tion tools. Vari­a­tion of these pa-ram­e­ters ap­pears to have no­table ef­fect on mi­crostruc­ture and topog­ra­phy of the ob­tained sur­face. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL130  
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THPAL131 Studies of Electropolishing and Oxypolishing Treated Diffusion Coated Nb3Sn Surfaces cavity, niobium, experiment, superconductivity 3954
 
  • U. Pudasaini, M.J. Kelley
    The College of William and Mary, Williamsburg, Virginia, USA
  • G.V. Eremeev, M.J. Kelley, C.E. Reece
    JLab, Newport News, Virginia, USA
  • M.J. Kelley, J. Tuggle
    Virginia Polytechnic Institute and State University, Blacksburg, USA
  
  The Nb3Sn-coated cav­i­ties aim to en­hance per­for-mance and sig­nif­i­cantly re­duce cost. Their fab­ri­ca­tion in­volves tin vapor dif­fu­sion coat­ing of Nb3Sn on the in­te­rior sur­face of a Nb cav­ity. Con­trolled re­moval of first few lay­ers to ob­tain a smoother and cleaner sur­face could be de­sir­able to im­prove the high field RF per­for-mance. Our first re­sults from the ap­pli­ca­tion of elec-trop­o­l­ish­ing and oxy­pol­ish­ing tech­niques on Nb3Sn-coated sur­faces in­di­cated re­duced sur­face rough­ness, and the sur­face com­po­si­tion ap­peared nom­i­nally un­changed. Sys­tem­atic stud­ies ex­plore the ef­fect of dif­fer­ent pol­ish-ing pa­ra­me­ters into the rough­ness and com­po­si­tion. We pre­sent the lat­est re­sults from SEM/EDS and AFM stud­ies of Nb3Sn-coated sam­ples treated with elec­trop­o­l­ish­ing and oxy­pol­ish­ing.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL131  
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THPAL142 Surface Characterization of NbTiN Films for Accelerator Applications site, FEL, detector, lattice 3975
 
  • D.R. Beverstock, M.J. Kelley, C.E. Reece, J.K. Spradlin, A-M. Valente-Feliciano
    JLab, Newport News, Virginia, USA
  
  Funding: Work supported by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
The de­vel­op­ment of next-gen­er­a­tion SRF cav­i­ties re­quires the de­ploy­ment of in­no­v­a­tive ma­te­r­ial so­lu­tions with RF per­for­mance be­yond bulk Nb. The­o­ret­i­cal in­ter­est has stim­u­lated ef­forts to grow and char­ac­ter­ize thin multi-layer su­per­con­duc­tor/in­su­la­tor/su­per­con­duc­tor (SIS) struc­tures for their po­ten­tial ca­pa­bil­ity of sup­port­ing oth­er­wise in­ac­ces­si­ble sur­face mag­netic fields in SRF cav­i­ties *. The ternary B1-com­pound NbTiN is among the can­di­date su­per­con­duct­ing ma­te­ri­als for SIS struc­tures. Sin­gle crys­tal NbTiN films with thick­nesses below 15 nm are also of in­ter­est for the de­vel­op­ment of high res­o­lu­tion, high sen­si­tiv­ity (SNSPD) de­tec­tors for par­ti­cle physics ap­pli­ca­tion. Using DC re­ac­tive mag­netron sput­ter­ing, NbTiN can be de­posited with nom­i­nal su­per­con­duct­ing pa­ra­me­ters. This con­tri­bu­tion pre­sents the on-go­ing ma­te­r­ial sur­face and su­per­con­duct­ing prop­er­ties char­ac­ter­i­za­tion in order to op­ti­mize the NbTiN films for each ap­pli­ca­tion.
* A Gurevich, "Maximum screening fields of superconducting multilayer structures", AIP ADVANCES 5, 017112 (2015) 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL142  
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THPAL143 Commissioning of JLab Vertical Cavity Processing System for SRF Nb Single Cell and Multicell Cavity With HF-Free Pulse-Reverse Electopolishing cavity, controls, niobium, MMI 3978
 
  • H. Tian, M. Lester, J. Musson, H.L. Phillips, C.E. Reece, C. Seaton
    JLab, Newport News, Virginia, USA
  
  Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177
Pulse re­versed elec­trop­o­l­ish­ing of nio­bium SRF cav­i­ties, using a di­lute aque­ous H2SO4 elec­trolyte with­out HF yields equiv­a­lent RF per­for­mance with tra­di­tional EP. Com­par­ing with pre­sent EP process for Nb SRF cav­ity which uses 1:10 vol­ume ratio of HF (49%) and H2SO4 (98%), pulse re­verse EP (also known as bipo­lar EP (BPEP)) is eco­log­i­cally friendly and uses rel­a­tively be­nign elec­trolyte op­tions for cav­ity pro­cess­ing. In this study, we re­port the com­mis­sion­ing of a new ver­ti­cal cav­ity pro­cess­ing sys­tem for SRF Nb sin­gle cell and multi-cell cav­i­ties with HF-free pulse-re­verse elec­trop­o­l­ish­ing at Jef­fer­son Lab, to­gether with RF test of cav­i­ties being processed. We re­port the scale-up chal­lenges and in­ter­pre­ta­tions from process R&D to im­ple­men­ta­tion. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL143  
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THPAL144 952.6 MHz SRF Cavity Development for JLEIC cavity, HOM, damping, electron 3982
 
  • R.A. Rimmer, W.A. Clemens, F. Fors, J. Guo, F.E. Hannon, J. Henry, F. Marhauser, L. Turlington, H. Wang, S. Wang
    JLab, Newport News, Virginia, USA
  
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177
JLab is de­vel­op­ing new SRF cav­ity de­signs at 952.6 MHz for the pro­posed Jef­fer­son Lab Elec­tron-Ion Col­lider (JLEIC). New cav­i­ties will be re­quired for the ion ring, cooler ERL and booster and even­tu­ally for an up­grade of the elec­tron ring to allow the high­est pos­si­ble bunch col­li­sion rate. The chal­lenges in­clude the need for high fun­da­men­tal mode power cou­plers and strong HOM damp­ing, with high HOM power ca­pa­bil­ity. Ini­tial focus is on the cooler ERL 5-cell cav­ity as this is a crit­i­cal com­po­nent for the strong, high en­ergy, bunched-beam cool­ing con­cept. 1-cell and 5-cell Nb pro­to­type cav­i­ties have been de­signed and fab­ri­cated. De­tails con­cern­ing the cav­ity fab­ri­ca­tion and test re­sults will be pre­sented. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL144  
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THPAL145 Magnetron R&D toward the Amplitude Modulation Control for SRF Accelerator injection, controls, cavity, simulation 3986
 
  • R.A. Rimmer, T. E. Plawski, H. Wang
    JLab, Newport News, Virginia, USA
  • A. Dudas, S.A. Kahn, M.L. Neubauer
    Muons, Inc, Illinois, USA
  
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and SBIR grant DE-SC0013203
The scheme of using a high ef­fi­ciency mag­netron to drive a su­per­con­duct­ing radio fre­quency (SRF) ac­cel­er­a­tor cav­ity needs not only the in­jec­tion phase lock­ing but also the am­pli­tude mod­u­la­tion to com­pen­sate the cav­ity's mi­crophomics caused cav­ity volt­age change and the beam load­ing vari­a­tion. To be able to do a fast and ef­fi­cient mod­u­la­tion, the mag­netron's mag­netic field has to be trimmed by an ex­ter­nal coil to com­pen­sate the fre­quency push­ing ef­fect due to the anode cur­rent change [1]. A low eddy cur­rent mag­netron body has been de­signed and built [2]. This paper will pre­sent the an­a­lyt­i­cal pre­dic­tion, sim­u­la­tion and ex­per­i­men­tal re­sults on the 2.45 GHz mag­netron test stand with the mod­u­la­tion fre­quency up to 1 kHz. In ad­di­tion, the pro­gresses on the in­jec­tion lock to a cop­per cav­ity, new 1497 MHz mag­netron pro­to­type, 13 kW high power mag­netron test stand de­vel­op­ment and newly built low level RF (LLRF) con­troller for the am­pli­tude mod­u­la­tion will be re­ported.
[1] M. Neubauer et al, THPIK123, Proceedings of IPAC 2017, Copenhagen, Denmark
[2] S. A. Kahn et al, THPIK121, Proceedings of IPAC 2017, Copenhagen, Denmark
 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL145  
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THPAL146 802 MHz ERL Cavity Design and Development cavity, collider, electron, hadron 3990
 
  • F. Marhauser, S. Castagnola, W.A. Clemens, J.G. Dail, P. Dhakal, F. Fors, J. Henry, R.A. Rimmer, L. Turlington, R.S. Williams
    JLab, Newport News, Virginia, USA
  • R. Calaga, K.M. Dr. Schirm, E. Jensen
    CERN, Geneva, Switzerland
  
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177, and CERN Contract NR. KE3080/ATS
In the frame­work of a col­lab­o­ra­tion be­tween CERN and JLab, an SRF ac­cel­er­at­ing cav­ity for en­ergy re­cov­ery linacs op­er­at­ing at 802 MHz was de­vel­oped in the con­text of the CERN's Large Hadron elec­tron Col­lider (LHeC) de­sign study. A sin­gle-cell and a five-cell cav­ity from fine grain high RRR nio­bium were built at JLab to val­i­date the basic RF de­sign in ver­ti­cal tests. Two cop­per sin­gle-cell cav­i­ties were pro­duced in par­al­lel for R&D pur­poses at CERN. The cav­ity de­sign has since been adapted as base­line for the main linac cav­i­ties in the pro­posed Pow­er­ful En­ergy Re­cov­ery Linac Ex­per­i­ment fa­cil­ity (PERLE) at Orsay. De­tails con­cern­ing the cav­ity fab­ri­ca­tion and test re­sults for the Nb cav­i­ties are pre­sented. 		 
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THPMF017 Operation Improvements and Emittance Reduction of the ESRF Booster emittance, booster, operation, quadrupole 4077
 
  • N. Carmignani, N. Benoist, J-F. B. Bouteille, M.G. Di Vito, F. Ewald, L. Farvacque, A. Franchi, O. Goudard, J.M. Koch, S. Lagarde, S.M. Liuzzo, B. Ogier, T.P. Perron, P. Raimondi, D. Robinson, F. Taoutaou, E.T. Taurel, P.V. Verdier, R. Versteegen, P. Vidal, S.M. White
    ESRF, Grenoble, France
  
  The ESRF stor­age ring will be re­placed by the Ex­tremely Bril­liant Source (EBS) in 2020 and the equi­lib­rium emit­tance will de­crease from the pre­sent 4 nmrad to 134 pmrad. The cur­rent in­jec­tor sys­tem, com­posed by a linac and a syn­chro­tron booster, will be used to in­ject into the new stor­age ring. To in­crease the in­jec­tion ef­fi­ciency in the new stor­age ring, three meth­ods to re­duce the hor­i­zon­tal emit­tance of the booster have been con­sid­ered and tested. This paper pre­sents the stud­ies and achieve­ments in terms of op­er­a­tion im­prove­ments and emit­tance re­duc­tion.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF017  
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THPMF019 ESRF-EBS Lattice Model with Canted Beamlines lattice, optics, MMI, quadrupole 4081
 
  • S.M. Liuzzo, N. Carmignani, J. Chavanne, L. Farvacque, T.P. Perron, P. Raimondi, S.M. White
    ESRF, Grenoble, France
  
  The ESRF Ex­tremely Bril­liant Source (ESRF-EBS) lat­tice model is up­dated to in­clude three canted beam­lines. The cells are mod­i­fied where nec­es­sary to in­clude 3-Pole Wig­gler (3PW), 2-Pole Wig­gler (2PW) and Short Bend­ing Mag­net (SBM) sources. Sev­eral lat­tices are ob­tained for the dif­fer­ent stages that will bring from com­mis­sion­ing to op­er­a­tion with users. A scheme for tune mod­i­fi­ca­tion keep­ing key op­tics knobs un­changed is pro­posed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF019  
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THPMF020 A 4th Generation Light Source for South-East Europe lattice, emittance, storage-ring, synchrotron 4084
 
  • H. Ghasem, R. Bartolini
    DLS, Oxfordshire, United Kingdom
  • D. Einfeld
    ESRF, Grenoble, France
  
  In Eu­rope, most of the Syn­chro­tron Light Sources are lo­cated in the mid­dle, west and north­ern re­gions while the south-east is still lack­ing any major pro­ject. Hence a new ini­tia­tive has been set up to pro­pose the con­struc­tion of a 4th Gen­er­a­tion Light Source in that re­gion. De­sign re­quire­ments limit the beam en­ergy be­tween 2.5 GeV to 3 GeV, the cir­cum­fer­ence is lim­ited to 350 m, the emit­tance should be smaller than 250 pm rad and at least 14 to 16 straights have to be avail­able for the users. Sev­eral mag-net con­fig­u­ra­tions have been in­ves­ti­gated and the re­sults re­vealed that the HMBA lat­tice can fully meets the re­quire­ments and is there­fore pro­posed for the Light Source in the SEE-re­gion of Eu­rope. These stud­ies show that for a 4th Gen­er­a­tion Light Source with en­er­gies up to 3 GeV a cir­cum­fer­ences of 350 m will be ad­e­quate.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF020  
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THPMF021 ESRF Operation Status injection, operation, power-supply, booster 4088
 
  • J.-L. Revol, J.C. Biasci, N. Carmignani, A. D'Elia, A. Franchi, L. Hardy, J. Jacob, I. Leconte, S.M. Liuzzo, H.P. Marques, T.P. Perron, E. Plouviez, P. Raimondi, B. Roche, K.B. Scheidt, L. Torino, S.M. White
    ESRF, Grenoble, France
  
  The Eu­ro­pean Syn­chro­tron Ra­di­a­tion Fa­cil­ity (ESRF) is un­der­go­ing the sec­ond phase (2015-2022) of an Up-grade which con­cerns its in­fra­struc­ture, beam­lines and X-ray source. This paper re­ports on the pre­sent op­er­a­tional source per­for­mance, high­light­ing the most re­cent de­vel­op­ments, and the prepa­ra­tion of the Ex­tremely Bril­liant Source pro­ject. The ren­o­va­tion of the in­jec­tor and the re­cent op­er­a­tion in top-up mode are also de­tailed.  
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THPMF034 Status Report of the Berlin Energy Recovery Linac Project BERLinPro gun, cathode, vacuum, cavity 4127
 
  • M. Abo-Bakr, W. Anders, Y. Bergmann, K.B. Bürkmann-Gehrlein, A.B. Büchel, P. Echevarria, A. Frahm, H.-W. Glock, F. Glöckner, F. Göbel, B.D.S. Hall, S. Heling, H.-G. Hoberg, A. Jankowiak, C. Kalus, T. Kamps, G. Klemz, J. Knobloch, J. Kolbe, G. Kourkafas, J. Kühn, B.C. Kuske, J. Kuszynski, A.N. Matveenko, M. McAteer, A. Meseck, R. Müller, A. Neumann, N. Ohm, K. Ott, E. Panofski, F. Pflocksch, L. Pichl, J. Rahn, M.A.H. Schmeißer, O. Schüler, M. Schuster, J. Ullrich, A. Ushakov, J. Völker
    HZB, Berlin, Germany
  • A. Bundels
    Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), Berlin, Germany
  
  Funding: Work supported by the German Bundesministerium für Bildung und Forschung, Land Berlin and grants of Helmholtz Association
The Helmholtz-Zen­trum Berlin is con­struct­ing the En­ergy Re­cov­ery Linac Pro­to­type BERLinPro, a demon­stra­tion fa­cil­ity for the sci­ence and tech­nol­ogy of ERLs for fu­ture light source ap­pli­ca­tions. BERLinPro is de­signed to ac­cel­er­ate a high cur­rent (100 mA, 50 MeV), high bril­liance (norm. emit­tance below 1 mm mrad) cw elec­tron beam. We re­port on the last year's progress, in­clud­ing the comis­sion­ing of the gun mod­ule as the first SRF com­po­nent to be in­stalled in BERLinPro. 		 
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THPMF038 Status of the BESSY VSR Project cavity, vacuum, operation, electron 4138
 
  • P. Schnizer, W. Anders, Y. Bergmann, P. Goslawski, H. Hartmut, A. Jankowiak, J. Knobloch, A. Neumann, K. Ott, M. Ries, A. Schälicke, A.V. Vélez
    HZB, Berlin, Germany
  
  BESSY VSR is set out to pro­vide a vari­able pulse pat­tern to the BESSY II users. This pro­ject is now fully funded and head­ing into its im­ple­men­ta­tion phase. The pulse pat­tern, con­sist­ing of long and short pulses, re­quire in­sert­ing cav­i­ties pro­vid­ing a 3rd and a 3.5th har­monic of the fun­da­men­tal har­monic of the ring. There­fore 1.5 and 1.75 GHz cav­i­ties are de­vel­oped with ap­pro­pri­ate higher order mode damp­ing spec­trum. Sim­i­larly the BESSY II ring and in­jec­tor chain has to be up­graded to pro­vide ap­pro­pri­ate di­ag­nos­tics and in­crease the in­jec­tion ef­fi­ciency. In this paper we give the cur­rent sta­tus of the pro­ject and give an overview of sci­en­tific chal­lenges cur­rently being tack­led.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF038  
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THPMF039 Study of Magnesium Photocathodes for Superconducting RF Photoinjectors laser, gun, cathode, cavity 4142
 
  • R. Xiang, A. Arnold, P.N. Lu, P. Murcek, J. Teichert, H. Vennekate
    HZDR, Dresden, Germany
  
  Funding: The work is supported by the German Federal Ministry of Education and Research (BMBF) grant 05K12CR1.
The su­per­con­duct­ing RF pho­toin­jec­tor (SRF Gun II) has suc­cess­fully served for the ELBE user fa­cil­ity at HZDR. Nev­er­the­less, the qual­ity of pho­to­cath­odes is one of the most crit­i­cal is­sues in im­prov­ing the sta­bil­ity and re­li­a­bil­ity for its ap­pli­ca­tion. Mag­ne­sium has a com­pa­ra­bly low work func­tion (3.6 eV) and shows a quan­tum ef­fi­ciency up to 0.3% after laser clean­ing. How­ever, the pre­sent clean­ing process with a high in­ten­sity laser beam is time con­sum­ing and pro­duces un­wanted sur­face rough­ness, which leads to a higher ther­mal emit­tance. Ther­mal treat­ment and Ex­cimer laser clean­ing for Mg cath­odes are in­ves­ti­gated as al­ter­na­tive meth­ods. In this work, the new clean­ing pro­ce­dures are tested and op­ti­mized, and the quan­tum ef­fi­ciency of Mg sam­ples with dif­fer­ent mi­crostruc­ture, com­po­si­tion and sup­pli­ers are com­pared. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF039  
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THPMF040 Experiences with the SRF Gun II for User Operation at the ELBE Radiation Source gun, radiation, undulator, electron 4145
 
  • J. Teichert, A. Arnold, M. Bawatna, P.E. Evtushenko, M. Gensch, B.W. Green, S. Kovalev, U. Lehnert, P.N. Lu, P. Michel, P. Murcek, H. Vennekate, R. Xiang
    HZDR, Dresden, Germany
  
  Funding: The work is supported by the German Federal Ministry of Education and Research (BMBF) grant 05K12CR1.
The sec­ond ver­sion of the su­per­con­duct­ing RF pho-toin­jec­tor (SRF Gun II) was suc­cess­fully com­mis­sioned at the ELBE ra­di­a­tion source in 2014. The gun fea­tures an im­proved 3.5-cell nio­bium cav­ity com­bined with a su­per-con­duct­ing so­le­noid in­te­grated in the cryo­stat. With a Mg pho­to­cath­ode the SRF Gun II is able to gen­er­ate bunches with up to 200 pC and with sub-ps length in CW mode with 100 kHz pulse fre­quency for the THz ra­di­a­tion fa-cil­ity at ELBE. In the ELBE linac, the beam is ac­cel­erat-ed, gets a proper cor­re­lated en­ergy spread, and is com-pressed in a mag­netic chi­cane. Sub-ps pulses are ob­tained pro­duc­ing co­her­ent dif­frac­tion ra­di­a­tion and su­per­ra­di­ant un­du­la­tor ra­di­a­tion. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF040  
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THPMF063 The MESA 15 kW cw 1.3 GHz Solid State Power Amplifier Prototype operation, experiment, linac, cavity 4216
 
  • R.G. Heine, F. Fichtner
    IKP, Mainz, Germany
  
  The Mainz En­ergy re­cov­er­ing Su­per­con­duct­ing Ac­cel­er­a­tor MESA is a multi-turn en­ergy re­cov­ery linac with beam en­er­gies in the 100 MeV regime cur­rently de­signed and build at In­sti­tut für Kern­physik (KPH) of Jo­hannes Guten­berg-Uni­ver­sität Mainz. The main ac­cel­er­a­tor con­sists of two su­per­con­duct­ing Rossendorf type mod­ules, while the in­jec­tor MAMBO (Mil­liAMpere BOoster) re­lies on nor­mal con­duct­ing tech­nolgy. The high power RF sys­tem is planned com­pletely in solid state tech­nol­ogy. With the high power de­mands of the nor­mal con­duct­ing RF cav­i­ties up-to-date tran­sis­tor tech­nol­ogy with in­creased power den­sity has to be used. A 15 kW CW power ampi­fier pro­to­type with the new tech­nol­ogy has been de­vel­oped by Sigma Phi Elec­tron­ics and de­liverd to KPH. In this paper we will pre­sent the re­sults of the per­for­mance mea­sure­ments of the am­pli­fier.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF063  
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THPMK066 Cryogenic Permanent Magnet Undulator of SSRF permanent-magnet, undulator, cryogenics, vacuum 4449
 
  • Y.Z. He, M.F. Qian, H.F. Wang, W. Zhang, Q.G. Zhou
    SINAP, Shanghai, People's Republic of China
  
  Funding: Work supported by the State Key Lab of Advanced Metals and Materials (2016-Z03) and the Youth Innovation Promotion Association of CAS (Grant No: 2017305)
The two Cryo­genic Per­ma­nent Mag­net Un­du­la­tors (CP­MU18 with PrFeB mag­nets P46H and CP­MU20 with NdFeB mag­nets N48H) were de­signed and de­vel­oped in SSRF in the past few years (2014-2017).This paper in­tro­duces mag­netic per­for­mance of the per­ma­nent mag­nets, de­sign pa­ra­me­ters of the two CPMUs, cryo­genic cool­ing and mag­netic field of the two CPMUs and so on. When gap of the two CPMUs is about 6.0 mm, the mea­sure­ment re­sults showed that the ef­fec­tive mag­netic field peak of CP­MU18 at 300 K and 77 K was 0.82 T, 0.92T, re­spec­tively, and the mag­netic field phase error is about 3 de­grees and 5 de­grees re­spec­tively. The ef­fec­tive mag­netic field peak of CP­MU20 at 300 K and 140 K was 0.94T and 1.03T, re­spec­tively, and the mag­netic field phase error was 3 de­grees and 3.5 de­grees re­spec­tively. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK066  
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THPMK106 Architectural Considerations for Recirculated and Energy-Recovered Hard XFEL Drivers FEL, linac, recirculation, operation 4560
 
  • D. Douglas, S.V. Benson, T. Powers, Y. Roblin, T. Satogata, C. Tennant
    JLab, Newport News, Virginia, USA
  • D. Angal-Kalinin, N. Thompson, A.E. Wheelhouse, P.H. Williams
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • T.K. Charles
    CERN, Geneva, Switzerland
  • R.C. York
    FRIB, East Lansing, Michigan, USA
  
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
A con­flu­ence of events mo­ti­vates dis­cus­sion of de­sign op­tions for hard XFEL dri­ver ac­cel­er­a­tors. Firstly, mul­ti­ple su­per­con­duct­ing ra­dio-fre­quency (SRF) dri­ven sys­tems are now on­line (Eu­ro­pean XFEL), in con­struc­tion (LCLS-II), or in de­sign (MARIE); these pro­vide in­creas­ing ev­i­dence of the trans­for­ma­tional po­ten­tial they offer for fun­da­men­tal sci­ence with its con­comi­tant ben­e­fits. Sec­ondly, op­er­a­tion of 12 GeV CEBAF* val­i­dates use of re­cir­cu­la­tion in high en­ergy SRF linacs. Thirdly, ad­vances in the analy­sis and con­trol of ef­fects such as co­her­ent syn­chro­tron ra­di­a­tion (CSR) and the mi­crobunch­ing in­sta­bil­ity (uBI) have been re­cently achieved. Col­lec­tively, these de­vel­op­ments offer in­sights pro­vid­ing ex­tended fa­cil­ity sci­ence reach, re­duced costs, mul­ti­plic­ity (i.e., sup­port of nu­mer­ous FELs op­er­at­ing over a range of wave­lengths), and en­hanced scal­a­bil­ity and upgrad­abil­ity (to higher pow­ers and en­er­gies). We will dis­cuss the re­la­tion­ship amongst the var­i­ous threads, and in­di­cate how they in­form de­sign choices for the sys­tem ar­chi­tec­ture of an op­tion for the UK-XFEL** - that of a staged multi-user X-ray FEL and nu­clear physics fa­cil­ity based on a multi-pass re­cir­cu­lat­ing SRF CW linac.
*M. Spata, "12 GeV CEBAF Initial Operations and Challenges", these proceedings.
**P. Williams et al., Proc. FLS2018, Shanghai, China (March 2018).
 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK106  
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THPMK144 Lattices for a 4th-Generation Synchrotron Light Source lattice, synchrotron, emittance, radiation 4639
 
  • G. K. Shamuilov
    Uppsala University, Uppsala, Sweden
  
  In­spired by the ESRF up­grade (Ex­tremely Bril­liant Source, EBS), I pre­sent some mod­ern lat­tices for a medium-sized 4th-gen­er­a­tion syn­chro­tron ra­di­a­tion source. They in­cor­po­rate new el­e­ments, such as anti-bend mag­nets. The com­posed lat­tices are op­ti­mized using a sim­ple dou­ble-ob­jec­tive al­go­rithm. Its goal is to min­i­mize the nat­ural emit­tance and ab­solute chro­matic­i­ties si­mul­ta­ne­ously. Then, the lat­tices are an­a­lyzed and com­pared to a ver­sion of the ESRF-EBS lat­tice scaled down in size. The de­sign is per­formed to meet the needs of the user com­mu­nity of the Siber­ian Syn­chro­tron and Ter­a­hertz Ra­di­a­tion Cen­tre under the um­brella of the Bud­ker In­sti­tute of Nu­clear Physics.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK144  
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THPML066 Filling Pattern Measurement System Upgrade in SSRF* operation, storage-ring, synchrotron, injection 4791
 
  • N. Zhang, F.Z. Chen, Y.M. Zhou
    SSRF, Shanghai, People's Republic of China
  
  Funding: Work supported by National Natural Science Foundation of China (No.11575282 No.11375255 No.11305253)
Fill­ing pat­tern af­fects var­i­ous op­er­a­tion per­for­mance of a syn­chro­tron light source. A new di­ag­nos­tic beam charge mon­i­tor (BCM) with high band­width multi-chan­nels dig­i­tizer was de­vel­oped to per­form bunch-by-bunch charge mea­sure­ment and record fill­ing pat­tern for SSRF stor­age ring. Sig­nals picked up from but­ton elec-trodes were sam­pled syn­chro­nously with RF fre­quency, and IQ (In-phase and Quad­ra­ture phase) sam­pling meth-od was em­ployed for noise-fil­ter­ing and phase in­de­pend-ence cal­i­bra­tion. Lay­out and eval­u­a­tion ex­per­i­ment of the sys­tem are pre­sented in this paper. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML066  
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THPML068 Upgrade of Bunch Phase Monitor at SSRF Storage Ring injection, storage-ring, pick-up, experiment 4797
 
  • Y.M. Zhou, Y.B. Leng, T. Wu, N. Zhang
    SSRF, Shanghai, People's Republic of China
  
  Beam in­sta­bil­ity is a se­ri­ous prob­lem for physics in beam di­ag­no­sis tech­nol­ogy. With re­gard to the eval­u­a­tion of lon­gi­tu­di­nal phase os­cil­la­tions dur­ing the tran­sient in­jec­tion process, bunch-by-bunch phase mea­sure­ment is a use­ful tool for study­ing the be­hav­ior of the re­filled bunches. A new up­graded beam phase mon­i­tor sys­tem with 1.2GHz band­width PXI wave­form dig­i­tizer has been de­vel­oped at Shang­hai syn­chro­tron ra­di­a­tion source (SSRF). Bunch-by-bunch phase in­for­ma­tion, re­trieved from but­ton pickup sig­nals, is cal­cu­lated by the zero-cross­ing de­tec­tion method with the best phase res­o­lu­tion of 0.4ps. The re­filled bunches can be sep­a­rated from the stored ones, and the lon­gi­tu­di­nal off­set of each re­filled bunch has been mea­sured. Sev­eral groups of ex­per­i­ments have been per­formed to ver­ify the re­peata­bil­ity of bunch-by-bunch phase mea­sure­ment, and some re­sults re­gard­ing re­filled bunches will be dis­cussed in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML068  
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THPML070 Point Spread Function Study of Quasi-Monochromatic X-Ray Pinhole Camera at SSRF simulation, photon, experiment, synchrotron 4803
 
  • B. Gao, H.J. Chen
    SINAP, Shanghai, People's Republic of China
  • J. Chen, Y.B. Leng
    SSRF, Shanghai, People's Republic of China
  
  Since 2009 an X-ray pin­hole cam­era that has been used to pre­sent the trans­verse beam size and emit­tance on di­ag­nos­tic beam line of the stor­age ring at SSRF. The real beam size is a func­tion of the image size of the CCD cam­era and point spread func­tion (PSF) of the sys­tem. The per­for­mance of the mea­sure­ment of the trans­verse elec­tron beam size is given by the width of the PSF of X-ray pin­hole cam­era. The con­tri­bu­tions to the PSF width are the PSF of pin­hole it­self due to dif­frac­tion, and the PSF of the screen and cam­era. An X-ray mono­chro­matic sys­tem has been es­tab­lished to mea­sure the PSF ac­cu­rately, and de­crease the vari­a­tion in the beam size be­tween the the­o­ret­i­cal val­ues and the mea­sured ones at SSRF. In this ar­ti­cle, both cal­cu­lated and mea­sured PSF of quasi-mono­chro­matic X-ray pin­hole cam­era will be pre­sented in de­tail.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML070  
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THPML072 Injection Comparison using Bunch-by-Bunch Beam Size Measurement System at SSRF injection, damping, storage-ring, betatron 4811
 
  • H.J. Chen, J. Chen, B. Gao, Y.B. Leng
    SINAP, Shanghai, People's Republic of China
  
  In­jec­tion tran­sient process hap­pens every 5-10 min­utes in stor­age ring dur­ing nor­mal top-up op­er­at­ing mode at SSRF, which is a proper win­dow for ma­chine sta­tus and in­jec­tion per­for­mance eval­u­a­tion. In the re­cent year, a bunch-by-bunch beam size mea­sure­ment sys­tem has been im­ple­mented at SSRF, which has the ca­pa­bil­ity to offer trans­verse bunch-by-bunch po­si­tion and size in­for­ma­tion and is a pow­er­ful tool for in­jec­tion study. In this paper, we sum­ma­rize three in­jec­tion study re­sults from July 2017 to April 2018, in­clud­ing be­ta­tron os­cil­la­tion am­pli­tude, spec­trum, hor­i­zon­tal tune and damp­ing time com­par­i­son. The os­cil­la­tion am­pli­tude and tem­po­ral be­hav­ior of re­cent in­jec­tion are all bet­ter than re­sults be­fore con­tributed to the in­jec­tion op­ti­miza­tion work dur­ing main­te­nance in 2018 win­ter. In ad­di­tion, the prin­ci­pal com­po­nent analy­sis method is also ap­plied to fur­ther study the in­jec­tion be­hav­ior in turn-by-turn or bunch-by-bunch di­rec­tion to the re­filled bucket.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML072  
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THPML122 Beta-SRF - A New Facility to Characterize SRF Materials near Fundamental Limits cavity, TRIUMF, linac, accelerating-gradient 4961
 
  • E. Thoeng
    UBC & TRIUMF, Vancouver, British Columbia, Canada
  • R.A. Baartman, R.E. Laxdal, B. Matheson, G. Morris, N. Muller, S. Saminathan
    TRIUMF, Vancouver, Canada
  • A. Chen
    UBC, Vancouver, Canada
  • T. Junginger
    Lancaster University, Lancaster, United Kingdom
  
  Funding: Natural Sciences and Engineering Research Council of Canada (NSERC) & UBC (NSERC) IsoSiM Program
De­mands of CW high-power LINAC re­quire SRF cav­i­ties op­er­at­ing at the fron­tier of high ac­cel­er­at­ing gra­di­ent and low RF power dis­si­pa­tion, i.e. high qual­ity fac­tor (Q0). This re­quire­ment poses a chal­lenge for stan­dard sur­face treat­ment recipes of SRF cav­i­ties. In a re­cent break­through, el­lip­ti­cal SRF cav­i­ties doped with Ni­tro­gen have been shown to im­prove Q0 by a fac­tor of 3, close to the fun­da­men­tal SRF limit. The fun­da­men­tal mech­a­nisms at mi­cro­scopic level and op­ti­mum dop­ing recipe, how­ever, have still not fully been un­der­stood. Ma­te­ri­als other than Nb have also been pro­posed for SRF cav­i­ties to over­come the fun­da­men­tal limit al­ready reached with Ni­tro­gen dop­ing, e.g. Nb3Sn, MgB2, and Nb-SIS mul­ti­layer. At TRI­UMF, a unique ex­per­i­men­tal fa­cil­ity is cur­rently being de­vel­oped to ad­dress these is­sues. This fa­cil­ity will be able to probe local sur­face mag­netic field in the order of the Lon­don Pen­e­tra­tion Depth (sev­eral tens of nm) via \beta decay de­tec­tion of a low-en­ergy ra­dioac­tive ion-beam. This al­lows depth-res­o­lu­tion and layer-by-layer mea­sure­ment of mag­netic field shield­ing ef­fec­tive­ness of dif­fer­ent SRF ma­te­ri­als at high-par­al­lel field (up to 200 mT). De­sign and cur­rent de­vel­op­ment of this fa­cil­ity will be pre­sented here, as well as com­mis­sion­ing and fu­ture mea­sure­ments strate­gies for new SRF ma­te­ri­als. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML122  
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THPML132 Cryogenic Performance of an SRF Deflecting Cavity Fabricated Using Alternative Techniques for the ARIEL eLinac cavity, linac, niobium, cryogenics 4992
 
  • D.W. Storey
    Victoria University, Victoria, B.C., Canada
  • R.E. Laxdal, Z.Y. Yao
    TRIUMF, Vancouver, Canada
  
  A 650 MHz SRF de­flect­ing mode cav­ity has been built and tested for use as a three-way beam sep­a­ra­tor in the ARIEL eLinac. The cav­ity op­er­ates in a TE-like mode, and has been op­ti­mized for high shunt im­ped­ance with min­i­mal lon­gi­tu­di­nal foot­print. The de­vice is the first SRF cav­ity to be fully fab­ri­cated in house at TRI­UMF. The re­quire­ments of the cav­ity al­lowed for the de­vel­op­ment of low cost man­u­fac­tur­ing tech­niques, in­clud­ing the use of Re­ac­tor grade nio­bium and at­mos­pheric pres­sure TIG weld­ing. The cav­ity has been fab­ri­cated and tested at 4 K and 2 K, ob­tain­ing a 4 K Qo of 4·108 at the op­er­at­ing volt­age of 0.3 MV, sur­pass­ing the goal volt­age and qual­ity fac­tor re­quired for op­er­a­tion. Re­sults of the cryo­genic tests of the cav­ity will be pre­sented here.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML132  
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