Keyword: cavity
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MOPAB016 Small Longitudinal Emittance Setup in Injectors with Gold Beam for Beam Energy Scan in RHIC emittance, operation, luminosity, extraction 90
 
  • H. Huang, C.J. Gardner, C. Liu, V. Schoefer, K. Zeno
    BNL, Upton, New York, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
In re­cent years, RHIC physics pro­gram calls for gold beam col­li­sions with en­er­gies at and lower than the nom­i­nal RHIC in­jec­tion en­ergy. To get shorter bunches at the three higher en­er­gies (9.8GeV/c, 7.3GeV/c and 4.75GeV/c), RHIC 28MHz cav­i­ties were used. The lon­gi­tu­di­nal emit­tance out of in­jec­tors needs to fit in the 28MHz cav­i­ties in RHIC. At two lower en­er­gies (4.6 and 3.85 GeV/c), the 9MHz RF cav­i­ties were used, which set dif­fer­ent re­quire­ments from in­jec­tors. Ex­ten­sive beam stud­ies were car­ried out to es­tab­lish needed beam pa­ra­me­ters, such as bunch in­ten­si­ties and lon­gi­tu­di­nal emit­tances. In gen­eral, enough in­ten­sity can be pro­vided for all en­er­gies within the lon­gi­tu­di­nal emit­tance con­straint. This paper sum­ma­rizes the re­cent in­jec­tor op­er­a­tion ex­pe­ri­ences for var­i­ous en­er­gies. 		 
poster icon Poster MOPAB016 [2.641 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB016  
About • paper received ※ 16 May 2021       paper accepted ※ 17 August 2021       issue date ※ 01 September 2021  
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MOPAB043 Validation of APS-U Beam Dynamics Using 6-GeV APS Beam HOM, simulation, lattice, impedance 189
 
  • L. Emery, P.S. Kallakuri, R.R. Lindberg, A. Xiao
    ANL, Lemont, Illinois, USA
  
  Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
Sev­eral beam mea­sure­ments at the Ad­vanced Pho­ton Sources were done with a low­ered-en­ergy beam of 6 GeV in order to ver­ify or val­i­date cal­cu­la­tion codes and some pre­dic­tions for the APS-U. Though the APS lat­tice is ob­vi­ously dif­fer­ent from that of the APS-U some as­pects of the beams at 6 GeV are sim­i­lar, for ex­am­ple, the syn­chro­tron ra­di­a­tion damp­ing rate. At 6 GeV, one can also store more cur­rent and run with a higher rf bucket al­low­ing the char­ac­ter­i­za­tion of larger mo­men­tum aper­ture lat­tices. We re­port mea­sure­ments (or plans of mea­sure­ments) on gen­eral in­sta­bil­i­ties thresh­olds, life­time, and other sub­tle ef­fects. The im­por­tant topic of ion in­sta­bil­i­ties at 6 GeV is cov­ered in a sep­a­rate paper by J. Calvey at this con­fer­ence. 		 
poster icon Poster MOPAB043 [0.829 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB043  
About • paper received ※ 20 May 2021       paper accepted ※ 23 June 2021       issue date ※ 02 September 2021  
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MOPAB045 Measurements and Simulations of High Charge Beam in the APS Booster booster, injection, simulation, extraction 197
 
  • J.R. Calvey, J.C. Dooling, K.C. Harkay, K.P. Wootton, C. Yao
    ANL, Lemont, Illinois, USA
  
  For the APS-Up­grade, swap-out in­jec­tion will re­quire the booster to sup­port up to 17 nC bunch charge, sev­eral times what is used in the pre­sent APS. Booster in­jec­tion ef­fi­ciency drops sharply at high charge, and is the pre­sent bot­tle­neck lim­it­ing high charge trans­port through the in­jec­tors. Par­ti­cle track­ing sim­u­la­tions have been used to un­der­stand what causes are lim­it­ing the in­jec­tion ef­fi­ciency, and to guide plans for im­prov­ing it. In par­tic­u­lar, bunch length blowup in the in­jected beam and beam load­ing in the RF cav­i­ties have been iden­ti­fied as the biggest fac­tors. Sim­u­la­tions and mea­sure­ments have also been done to char­ac­ter­ize beam prop­er­ties along the booster en­ergy ramp. So far, a bunch charge of 12 nC has been suc­cess­fully ex­tracted from the booster.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB045  
About • paper received ※ 19 May 2021       paper accepted ※ 26 July 2021       issue date ※ 19 August 2021  
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MOPAB046 Plan for Operating the APS-Upgrade Booster with a Frequency Sweep injection, booster, extraction, emittance 201
 
  • J.R. Calvey, T.G. Berenc, A.R. Brill, L. Emery, T. Fors, K.C. Harkay, T.J. Madden, N. Sereno, U. Wienands
    ANL, Lemont, Illinois, USA
  • A. Gu
    UCB, Berkeley, California, USA
  
  The APS-Up­grade pre­sents sev­eral chal­leng­ing de­mands to the booster syn­chro­tron. Swap-out in­jec­tion re­quires the booster to cap­ture a high charge bunch (up to 17 nC), ac­cel­er­ate it to 6 GeV, and main­tain a low emit­tance at ex­trac­tion for in­jec­tion into the stor­age ring. To ac­com­mo­date these con­flict­ing de­mands, the RF fre­quency will be ramped be­tween in­jec­tion and ex­trac­tion. How­ever, the RF cav­ity tuners will re­main sta­tic, which means the cou­plers will need to with­stand a high re­flected power at ex­trac­tion. This paper pre­sents a plan for a sys­tem that will meet the re­quire­ments for in­jec­tion ef­fi­ciency, ex­tracted emit­tance, and equiv­a­lent power at the cou­pler. Re­sults from track­ing sim­u­la­tions and beam stud­ies with a fre­quency ramp will also be shown.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB046  
About • paper received ※ 28 May 2021       paper accepted ※ 02 June 2021       issue date ※ 15 August 2021  
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MOPAB050 Spatial Autoresonant Acceleration of Electrons by an Axysimmetric Transverse Electric Field electron, resonance, acceleration, cyclotron 217
 
  • E.A. Orozco, O. Otero Olarte
    UIS, Bucaramanga, Colombia
  
  In this re­search, The au­tores­o­nance ac­cel­er­a­tion of elec­trons by an ax­isym­met­ric trans­verse elec­tric field in pres­ence of a sta­tion­ary in­ho­mo­ge­neous mag­netic field is stud­ied. The dy­nam­ics of elec­trons is de­ter­mined by the nu­mer­i­cal so­lu­tion of the rel­a­tivis­tic New­ton-Lorentz equa­tion using a fi­nite dif­fer­ence scheme. The in­ho­mo­ge­neous ex­ter­nal mag­netic field is gen­er­ated with a three-coil sys­tem and cal­cu­lated using the Biot-Savart law. The elec­trons move along a TE011 cylin­der cav­ity in a sta­tion­ary mag­netic field whose axis co­in­cides with the cav­ity axis. The mag­netic field pro­file ob­tained is such that it keeps the phase dif­fer­ence be­tween the elec­tric field vec­tor of the mi­crowave mode and the ve­loc­ity vec­tor of the par­ti­cle within the ac­cel­er­a­tion band. For an elec­tron in­jected lon­gi­tu­di­nally with an en­ergy of 1 keV and that starts at the ra­dial mid­point of the cav­ity, it is ac­cel­er­ated up to an en­ergy of about 185 keV using an elec­tric field am­pli­tude of 14 kV/cm and a fre­quency of 2.45 GHz at a dis­tance of 14 cm.  
poster icon Poster MOPAB050 [3.298 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB050  
About • paper received ※ 17 May 2021       paper accepted ※ 15 June 2021       issue date ※ 30 August 2021  
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MOPAB068 Collective Effects Studies for the SOLEIL Upgrade impedance, synchrotron, storage-ring, feedback 274
 
  • A. Gamelin, D. Amorim, P. Brunelle, W. Foosang, A. Loulergue, L.S. Nadolski, R. Nagaoka, R. Ollier, M.-A. Tordeux
    SOLEIL, Gif-sur-Yvette, France
  
  The SOLEIL up­grade pro­ject aims to re­place the ac­tual SOLEIL stor­age ring by a 4th gen­er­a­tion light source. The pro­ject has just fin­ished its con­cep­tual de­sign re­port (CDR) phase*. Com­pared to the SOLEIL stor­age ring, the up­graded stor­age ring de­sign in­cludes many new fea­tures of 4th gen­er­a­tion light sources that will im­pact col­lec­tive ef­fects, such as re­duced beam pipe aper­tures, a smaller mo­men­tum com­paction fac­tor and the pres­ence of har­monic cav­i­ties (HC). To mit­i­gate them, we rely on sev­eral damp­ing mech­a­nisms pro­vided by the syn­chro­tron ra­di­a­tion, the trans­verse feed­back sys­tem, and the HC (Lan­dau damp­ing and bunch length­en­ing). This ar­ti­cle pre­sents a first es­ti­mate of the col­lec­tive ef­fects im­pact of the up­graded de­sign.
* Conceptual Design Report: Synchrotron SOLEIL Upgrade, 2021, in press. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB068  
About • paper received ※ 17 May 2021       paper accepted ※ 02 June 2021       issue date ※ 20 August 2021  
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MOPAB069 Equilibrium Bunch Density Distribution with Multiple Active and Passive RF Cavities beam-loading, impedance, synchrotron, storage-ring 278
 
  • A. Gamelin
    SOLEIL, Gif-sur-Yvette, France
  • N. Yamamoto
    KEK, Ibaraki, Japan
  
  This paper de­scribes a method to get the equi­lib­rium bunch den­sity dis­tri­b­u­tion with an ar­bi­trary num­ber of ac­tive or pas­sive RF cav­i­ties in uni­form fill­ing. This method is an ex­ten­sion of the one pre­sented by M. Ven­turini which as­sumes a pas­sive har­monic cav­ity and no beam load­ing in the main RF cav­ity*.
*M. Venturini, "Passive higher-harmonic rf cavities with general settings and multibunch instabilities in electron storage rings," Physical Review Accelerators and Beams, 2018. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB069  
About • paper received ※ 17 May 2021       paper accepted ※ 23 June 2021       issue date ※ 28 August 2021  
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MOPAB070 mbtrack2, a Collective Effect Library in Python impedance, collective-effects, simulation, synchrotron 282
 
  • A. Gamelin, W. Foosang, R. Nagaoka
    SOLEIL, Gif-sur-Yvette, France
  
  This ar­ti­cle in­tro­duces mb­track2, a col­lec­tive ef­fect li­brary writ­ten in python3. The idea be­hind mb­track2 is to build a co­her­ent ob­ject-ori­ented frame­work to work on col­lec­tive ef­fects in syn­chro­trons. mb­track2 is com­posed of dif­fer­ent mod­ules al­low­ing to eas­ily write scripts for sin­gle bunch or multi-bunch track­ing using MPI par­al­leliza­tion in a trans­par­ent way. The base of the track­ing model of mb­track2 is in­spired by mb­track, a C multi-bunch track­ing code ini­tially de­vel­oped at SOLEIL*. In ad­di­tion, many tools to pre­pare or analyse track­ing sim­u­la­tions are in­cluded.
* R. Nagaoka, R. Bartolini, and J. Rowland, Studies of Collective Effects in SOLEIL and Diamond Using the Multiparticle Tracking Codes SBTRACK and MBTRACK, in Proc. PAC’09, 2009. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB070  
About • paper received ※ 17 May 2021       paper accepted ※ 06 July 2021       issue date ※ 23 August 2021  
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MOPAB072 Single-Bunch Thresholds for the Diamond-II Storage Ring impedance, simulation, storage-ring, beam-loading 290
 
  • T. Olsson, R.T. Fielder
    DLS, Oxfordshire, United Kingdom
  
  The pro­posed Di­a­mond Light Source up­grade will see the stor­age ring re­placed with a multi­bend achro­mat lat­tice, in­creas­ing the ca­pac­ity of the fa­cil­ity whilst re­duc­ing the emit­tance and pro­vid­ing higher bright­ness for the users. As part of the de­sign work, track­ing stud­ies have been per­formed to de­ter­mine the sin­gle-bunch thresh­olds in­clud­ing both the re­sis­tive-wall and geo­met­ric con­tri­bu­tions to the im­ped­ance. As the ma­chine de­sign also fore­sees a third order har­monic cav­ity, the paper also pro­vides an ini­tial as­sess­ment of the ef­fects of bunch length­en­ing on the sin­gle-bunch thresh­olds.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB072  
About • paper received ※ 18 May 2021       paper accepted ※ 01 June 2021       issue date ※ 18 August 2021  
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MOPAB079 Experience of the First Six Years Operations and Plans in NSlS-II operation, MMI, feedback, vacuum 308
 
  • G.M. Wang
    BNL, Upton, New York, USA
  
  NSLS-II is a 3 GeV third-gen­er­a­tion syn­chro­tron light source at BNL. The stor­age ring was com­mis­sioned in 2014 and began its rou­tine op­er­a­tions in the De­cem­ber of the same year. Since then, we have been con­tin­u­ously in­stalling and com­mis­sion­ing new in­ser­tion de­vices, their front-ends, and beam­lines. At this point, the fa­cil­ity hosts 28 op­er­at­ing beam­lines from var­i­ous ra­di­a­tion sources, in­clud­ing damp­ing wig­gler, IVU, EPU, 3PW, and bend­ing mag­nets for in­frared beam­lines. Over the past six years, the stor­age ring per­for­mance con­tin­u­ously im­proved, in­clud­ing 500 mA with lim­ited in­ser­tion de­vices close due to RF power lim­i­ta­tion and rou­tinely 400 mA top off op­er­a­tion, >95% op­er­a­tion re­li­a­bil­ity, main­te­nance of beam mo­tion short- and long-term sta­bil­ity. In this paper, we re­port NSLS-II ac­cel­er­a­tor op­er­a­tions ex­pe­ri­ence and plans for fu­ture fa­cil­ity de­vel­op­ments.  
poster icon Poster MOPAB079 [2.064 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB079  
About • paper received ※ 17 May 2021       paper accepted ※ 21 June 2021       issue date ※ 11 August 2021  
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MOPAB092 Project of Wuhan Photon Source storage-ring, injection, linac, dipole 346
 
  • H.H. Li, Y. Deng, J.H. He, Y. Nie, L. Tang, J. Wang, Y.X. Zhu
    IAS, Wuhan City, People’s Republic of China
  
  Wuhan Pho­ton Source (WHPS) has been de­signed as a fourth-gen­er­a­tion light source, which con­sists of a low en­ergy stor­age ring (1.5 GeV), a medium en­ergy stor­age ring (4.0 GeV), and a linac work­ing as a full en­ergy in­jec­tor. It has been planned to build the low en­ergy light source first as the Phase I pro­ject, and then the medium en­ergy light source after its com­ple­tion. The low en­ergy stor­age ring has been op­ti­mized with the main de­sign pa­ra­me­ters as fol­low­ing: An 8-cell, 500 mA stor­age ring, with a cir­cum­fer­ence of 180 m and na­ture emit­tance 238.4 pm-rad. Based on hy­brid-7BA lat­tice struc­ture, it reaches the soft X-ray dif­frac­tion limit. And at the mid­dle of each cell, a 3.5 T su­perB mag­net is used to ex­tend the pho­ton en­ergy to the hard X-ray re­gion. The swap-out in­jec­tion is cho­sen due to the small dy­namic aper­ture and a full en­ergy S-band LINAC will be used as its in­jec­tor. A 3rd har­monic cav­ity is de­signed for bunch length­en­ing to keep a suf­fi­cient life­time. More de­tails of the WHPS phase I pro­ject will be de­scribed in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB092  
About • paper received ※ 10 June 2021       paper accepted ※ 23 June 2021       issue date ※ 30 August 2021  
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MOPAB107 RF Plans for the Diamond-II Upgrade HOM, linac, booster, gun 391
 
  • C. Christou, P. Gu, P.J. Marten, S.A. Pande, A.F. Rankin
    DLS, Oxfordshire, United Kingdom
  
  The RF sys­tem for the pro­posed Di­a­mond-II up­grade will be based on nor­mal-con­duct­ing EU HOM-damped cav­i­ties pow­ered by high pow­ered solid state am­pli­fiers and con­trolled by dig­i­tal low level RF sys­tems built on the mi­croTCA plat­form. Rea­sons for these de­sign choices are dis­cussed, and ex­pe­ri­ence of the se­lected tech­nolo­gies in the Di­a­mond-I ring are re­viewed. The stor­age ring will also in­clude a third har­monic cav­ity, and the dif­fer­ent de­sign op­tions for this de­vice are dis­cussed. RF de­sign of the booster ring is pre­sented, and de­tails are given of an up­graded linac and gun de­sign in­tended to im­prove the charge de­liv­ered for top-up.  
poster icon Poster MOPAB107 [1.703 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB107  
About • paper received ※ 18 May 2021       paper accepted ※ 20 May 2021       issue date ※ 20 August 2021  
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MOPAB108 ESRF-EBS 352.37 MHz Radio Frequency System SRF, operation, MMI, HOM 395
 
  • J. Jacob, P.B. Borowiec, A. D’Elia, G. Gautier, V. Serrière
    ESRF, Grenoble, France
  
  The ESRF 352 MHz Radio Fre­quency (RF) sys­tem has been up­graded and tai­lored to the new 4th Gen­er­a­tion Ex­tremely Bril­liant Source EBS, that was in­stalled in 2019 and com­mis­sioned in 2020. The five for­mer five-cell cav­i­ties were re­placed with 13 sin­gle cell strongly HOM damped cav­i­ties that were de­vel­oped in house, 10 of which are pow­ered from ex­ist­ing 1 MW kly­stron trans­mit­ters. The re­main­ing three cav­i­ties are in­di­vid­u­ally fed by three 150 kW solid state am­pli­fiers. All this re­quired a re­con­struc­tion in record time of an elab­o­rate WR2300 wave­guide net­work. The low level RF sys­tem as well as the cav­ity and trans­mit­ter con­trol sys­tem have been re­built. The RF de­sign, com­mis­sion­ing and op­er­a­tion ex­pe­ri­ence will be re­ported, in­clud­ing plans for a 4th har­monic RF sys­tem for bunch length­en­ing to fur­ther im­prove the per­for­mance of the new EBS ring.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB108  
About • paper received ※ 19 May 2021       paper accepted ※ 27 May 2021       issue date ※ 28 August 2021  
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MOPAB127 Construction of an Impedance Model for Diamond-II impedance, simulation, lattice, dipole 455
 
  • R.T. Fielder, T. Olsson
    DLS, Oxfordshire, United Kingdom
  
  Im­ped­ance mod­els for ac­cel­er­a­tors have tra­di­tion­ally been pre­sented in a sta­tic form, usu­ally as ta­bles or spread­sheets which must be read man­u­ally. As part of the Di­a­mond-II up­grade work, we have de­vel­oped an im­ped­ance model using a lat­tice struc­ture. This al­lows more di­rect in­te­gra­tion with sim­u­la­tion codes while keep­ing im­por­tant in­for­ma­tion eas­ily human read­able. We pre­sent here a de­scrip­tion of this im­ple­men­ta­tion method, along with an overview of the Di­a­mond-II im­ped­ance model de­rived from the lat­est en­gi­neer­ing de­sign.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB127  
About • paper received ※ 18 May 2021       paper accepted ※ 20 May 2021       issue date ※ 27 August 2021  
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MOPAB146 Status of the C-Band Engineering Research Facility (CERF-NM) Test Stand Development at LANL GUI, klystron, controls, radiation 509
 
  • D. Gorelov
    Private Address, Los Alamos, USA
  • R.L. Fleming, S.K. Lawrence, J.W. Lewellen, D. Perez, M.E. Schneider, E.I. Simakov, T. Tajima
    LANL, Los Alamos, New Mexico, USA
  • M.E. Middendorf
    ANL, Lemont, Illinois, USA
  
  Funding: LDRD-DR Project 20200057DR
C-Band struc­tures re­search is of in­creas­ing in­ter­est to the ac­cel­er­a­tor com­mu­nity. The RF fre­quency range of 4-6 GHz gives the op­por­tu­nity to achieve sig­nif­i­cant in­crease in the ac­cel­er­at­ing gra­di­ent, and hav­ing the wake­fields at the man­age­able lev­els, while keep­ing the geo­met­ric di­men­sions of the struc­ture tech­no­log­i­cally con­ve­nient. Strong team of sci­en­tists, in­clud­ing the­o­rists re­search­ing prop­er­ties of met­als under stress­ful ther­mal con­di­tions and high elec­tro­mag­netic fields, met­al­lur­gists work­ing with cop­per as well as al­loys of in­ter­est, and ac­cel­er­a­tor sci­en­tists de­vel­op­ing new struc­ture de­signs, is formed at LANL to de­velop a CERF-NM fa­cil­ity. A 50 MW, 5.712 GHz Canon kly­stron, was pur­chased in 2019, and laid the basis for this fa­cil­ity. As of Jan-21, the con­struc­tion of the Test Stand has been fin­ished and the high gra­di­ent pro­cess­ing of the wave­guide com­po­nents has been started. Fu­ture plans in­clude high gra­di­ent test­ing of var­i­ous ac­cel­er­at­ing struc­tures, in­clud­ing bench­mark C-band ac­cel­er­at­ing cav­ity, a pro­ton ß=0.5 cav­ity, and cav­i­ties made from dif­fer­ent al­loys. An up­grade to the fa­cil­ity is planned to allow for test­ing ac­cel­er­a­tor cav­i­ties at cryo­genic tem­per­a­tures. 		 
poster icon Poster MOPAB146 [3.778 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB146  
About • paper received ※ 17 May 2021       paper accepted ※ 26 May 2021       issue date ※ 25 August 2021  
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MOPAB155 Magnetic Breakdowns in Side-Coupled X-Band Accelerating Structures impedance, coupling, simulation, accelerating-gradient 540
 
  • S.P. Antipov, P.V. Avrakhov, S.V. Kuzikov
    Euclid TechLabs, Solon, Ohio, USA
  • V.A. Dolgashev
    SLAC, Menlo Park, California, USA
  • C. Jing
    Euclid Beamlabs, Bolingbrook, USA
  
  Funding: DOE SBIR
Side cou­pled ac­cel­er­at­ing struc­tures are pop­u­lar in the in­dus­trial re­al­iza­tions of linacs due to their high shunt im­ped­ance and ease of tun­ing. We de­signed and fab­ri­cated a side-cou­pled X-band ac­cel­er­at­ing struc­ture that achieved 133 MOhm/m shut im­ped­ance. This struc­ture was fab­ri­cated out of two halves using a novel braze­less ap­proach. The two cop­per halves are joined to­gether using a stain­less steel join­ing piece with knife edges that bite into cop­per. This struc­ture had been tested at high power at SLAC Na­tional Ac­cel­er­a­tor Lab­o­ra­tory. The per­for­mance of the struc­ture had been lim­ited by mag­netic break­downs on the side-cou­pling cells. In this paper we will pre­sent re­sults of the high gra­di­ent tests and af­ter-test analy­sis. Scan­ning elec­tron mi­croscopy im­ages show a typ­i­cal mag­netic-field in­duced break­down. 		 
poster icon Poster MOPAB155 [1.069 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB155  
About • paper received ※ 20 May 2021       paper accepted ※ 23 June 2021       issue date ※ 21 August 2021  
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MOPAB187 Design and Calculation of the RF System of DC140 Cyclotron cyclotron, coupling, simulation, resonance 636
 
  • A.S. Zabanov, V.B. Zarubin
    JINR/FLNR, Moscow region, Russia
  • J. Franko, G.G. Gulbekyan, I.V. Kalagin, N.Yu. Kazarinov, S.V. Mitrofanov, V.A. Sokolov, K. Verlamov
    JINR, Dubna, Moscow Region, Russia
  
  Flerov Lab­o­ra­tory of Nu­clear Re­ac­tion of Joint In­sti­tute for Nu­clear Re­search car­ries out the works under cre­at­ing of FLNR JINR Ir­ra­di­a­tion Fa­cil­ity based on the cy­clotron DC140. The fa­cil­ity is in­tended for SEE test­ing of mi­crochip, for pro­duc­tion of track mem­branes and for solv­ing of ap­plied physics prob­lems. The main sys­tems of DC140 are based on the DC72 cy­clotron ones that now are under re­con­struc­tion. The DC140 cy­clotron is in­tended for ac­cel­er­a­tion of heavy ions with mass-to-charge ratio A/Z within in­ter­val from 5 to 5.5 up to two fixed en­er­gies 2.124 and 4.8 MeV per unit mass. The in­ten­sity of the ac­cel­er­ated ions will be about 1 pmcA for light ions (A<86) and about 0.1 pmcA for heav­ier ions (A>132). The de­signed RF-sys­tem of the DC-72 cy­clotron with a half-wave cav­ity is not suit­able due to the big ver­ti­cal size. For this rea­son, a new quar­ter-wave RF-sys­tem was de­vel­oped for the DC140 cy­clotron pro­ject. The re­sults of cal­cu­lat­ing the pa­ra­me­ters of the new RF-sys­tem are given in this work.  
poster icon Poster MOPAB187 [0.488 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB187  
About • paper received ※ 17 May 2021       paper accepted ※ 24 May 2021       issue date ※ 30 August 2021  
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MOPAB190 An 8 GeV Linac as the Booster Replacement in the Fermilab Power Upgrade linac, injection, cryomodule, booster 643
 
  • D.V. Neuffer, S.A. Belomestnykh, M. Checchin, D.E. Johnson, S. Posen, E. Pozdeyev, V.S. Pronskikh, N. Solyak, V.P. Yakovlev
    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.
In­creas­ing the Main In­jec­tor (MI) beam power above ~1.2 MW re­quires re­place­ment of the 8 GeV Booster by a higher in­ten­sity al­ter­na­tive. Pre­vi­ously, rapid-cy­cling syn­chro­tron (RCS) and Linac so­lu­tions were con­sid­ered for this pur­pose. In this paper, we con­sider the Linac ver­sion that pro­duces 8 GeV H− beam for in­jec­tion into the Re­cy­cler Ring (RR) or Main In­jec­tor (MI). The Linac takes ~1 GeV beam from the PIP-II Linac and ac­cel­er­ates it to ~2 GeV in a cw SRF linac, fol­lowed by a ~2-8 GeV pulsed linac using 1300 MHz cry­omod­ules. The linac com­po­nents in­cor­po­rate re­cent im­prove­ments in SRF tech­nol­ogy. The linac con­fig­u­ra­tion and beam dy­nam­ics re­quire­ments are pre­sented. In­jec­tion op­tions are dis­cussed. Re­search needed to im­ple­ment the Booster re­place­ment is de­scribed. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB190  
About • paper received ※ 15 May 2021       paper accepted ※ 28 May 2021       issue date ※ 14 August 2021  
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MOPAB191 Method Development for Cavity Failure Compensation in a Superconducting Linac linac, emittance, lattice, ECR 647
 
  • F. Bouly
    LPSC, Grenoble Cedex, France
  
  Re­li­a­bil­ity is a major chal­lenge within the per­spec­tive of im­prov­ing the per­for­mances and sus­tain­abil­ity of MegaWatt class ac­cel­er­a­tors. To op­ti­mize the op­er­a­tional costs of such ac­cel­er­a­tors the avail­abil­ity re­quire­ments are be­com­ing more and more chal­leng­ing. These re­quire­ments are even more strin­gent in the case of Ac­cel­er­a­tor Dri­ven sys­tems (ADS). As an ex­am­ple, for the MYRRHA (Mul­ti­pur­pose Hy­brid Re­search Re­ac­tor for High-tech Ap­pli­ca­tions) ADS demon­stra­tor, the ac­tual avail­abil­ity limit is set to a max­i­mum of 10 beam in­ter­rup­tions (longer than 3 sec­onds) over a 3-month op­er­at­ing cycle. For this pur­pose, the ac­cel­er­a­tor de­sign is based on a re­dun­dant and fault-tol­er­ant scheme to en­able rapid mit­i­ga­tion of a cav­ity fail­ure. The adopted strat­egy is to apply for local com­pen­sa­tion: a failed cav­ity is com­pen­sated by sev­eral neigh­bor­ing cav­i­ties. Beam dy­nam­ics stud­ies and method de­vel­op­ments to apply such a fail­ure com­pen­sa­tion scheme are here re­viewed. First sim­u­la­tion re­sults for su­per­con­duct­ing linac re­tun­ing and po­ten­tial fu­ture im­prove­ments will be dis­cussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB191  
About • paper received ※ 19 May 2021       paper accepted ※ 21 May 2021       issue date ※ 30 August 2021  
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MOPAB192 LILac Energy Upgrade to 13 MeV linac, proton, controls, LLRF 651
 
  • B. Koubek, S. Altürk, M. Busch, H. Höltermann, J.D. Kaiser, H. Podlech, U. Ratzinger, M. Schuett, M. Schwarz, W. Schweizer, D. Strehl, R. Tiede, C. Trageser
    BEVATECH, Frankfurt, Germany
  • A. Brunzel, P. Nonn, H. Schlarb
    DESY, Hamburg, Germany
  • A.V. Butenko, D.E. Donets, B.V. Golovenskiy, A. Govorov, K.A. Levterov, D.A. Lyuosev, A.A. Martynov, V.A. Monchinsky, D.O. Ponkin, K.V. Shevchenko, I.V. Shirikov, E. Syresin
    JINR, Dubna, Moscow Region, Russia
  
  In the frame of the NICA (Nu­clotron-based Ion Col­lider fA­cil­ity) ion col­lider up­grade a new light ion LINAC for pro­tons and ions will be built in col­lab­o­ra­tion be­tween JINR and BE­VAT­ECH GmbH. While ions with a mass-to-charge ratio up to 3 will be fed into the NU­CLOTRON ring with an en­ergy of 7 MeV/u, pro­tons are sup­posed to be ac­cel­er­ated up to an en­ergy of 13 MeV using a third IH struc­ture. This en­ergy up­grade com­prises a third IH struc­ture, a dual-use De­buncher cav­ity as well as an ex­ten­sion of the LLRF con­trol sys­tem built on Mi­croTCA tech­nol­ogy.  
poster icon Poster MOPAB192 [4.914 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB192  
About • paper received ※ 11 May 2021       paper accepted ※ 31 May 2021       issue date ※ 02 September 2021  
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MOPAB194 First 3D Printed IH-Type Linac Structure - Proof-of-Concept for Additive Manufacturing of Linac rf Cavities vacuum, cyclotron, experiment, linac 654
 
  • H. Hähnel, U. Ratzinger
    IAP, Frankfurt am Main, Germany
  
  Ad­di­tive man­u­fac­tur­ing (or "3D print­ing") has be­come a pow­er­ful tool for rapid pro­to­typ­ing and man­u­fac­tur­ing of com­plex geome­tries. As tech­nol­ogy is evolv­ing, the qual­ity and ac­cu­racy of parts man­u­fac­tured this way is ever im­prov­ing. Es­pe­cially in­ter­est­ing for the world of par­ti­cle ac­cel­er­a­tors is the process of 3D print­ing of stain­less steel (and cop­per) parts. We pre­sent the first fully func­tional IH-type drift tube struc­ture man­u­fac­tured by metal 3D print­ing. A 433 MHz pro­to­type cav­ity has been con­structed to act as a proof-of-con­cept for the tech­nol­ogy. The cav­ity is de­signed to be UHV ca­pa­ble and in­cludes cool­ing chan­nels reach­ing into the stems of the DTL struc­ture. We pre­sent the first ex­per­i­men­tal re­sults for this pro­to­type.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB194  
About • paper received ※ 18 May 2021       paper accepted ※ 01 June 2021       issue date ※ 19 August 2021  
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MOPAB195 Development of a Disk-and-Washer Cavity for the J-PARC Muon g-2/EDM Experiment experiment, linac, quadrupole, coupling 658
 
  • Y. Takeuchi, J. Tojo
    Kyushu University, Fukuoka, Japan
  • E. Cicek, K. Futatsukawa, N. Kawamura, T. Mibe, M. Otani, T. Yamazaki, M. Yoshida
    KEK, Ibaraki, Japan
  • Y. Iwashita
    Kyoto ICR, Uji, Kyoto, Japan
  • R. Kitamura, Y. Kondo, T. Morishita
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  • Y. Nakazawa
    Ibaraki University, Hitachi, Ibaraki, Japan
  • N. Saito
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  • Y. Sue, K. Sumi, M. Yotsuzuka
    Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan
  • H.Y. Yasuda
    University of Tokyo, Tokyo, Japan
  
  At J-PARC, an ex­per­i­ment using muons ac­cel­er­ated by a linac is planned to mea­sure the anom­alous mag­netic mo­ment of muons and to search for the elec­tric di­pole mo­ment. A 1296 MHz disk and washer (DAW) cou­pled cav­ity linac (CCL) is being de­vel­oped for use in the mid­dle beta sec­tion of the muon linac. The DAW CCL con­sists of 14 tanks with 11 cells each. All tanks are con­nected by bridge cou­plers and elec­tro­mag­netic quadru­pole dou­blets for fo­cus­ing are in­stalled in each bridge cou­pler. The basic de­sign of the DAW cav­ity has al­ready been com­pleted, and now de­tailed cav­ity de­sign stud­ies and man­u­fac­tur­ing process stud­ies are un­der­way. In this poster, we will re­port about these stud­ies and the prepa­ra­tion sta­tus of man­u­fac­tur­ing the DAW cav­ity.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB195  
About • paper received ※ 20 May 2021       paper accepted ※ 01 June 2021       issue date ※ 26 August 2021  
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MOPAB203 Benchmark of Superconducting Cavity Models at SNS Linac linac, superconducting-cavity, simulation, operation 671
 
  • A.P. Shishlo
    ORNL, Oak Ridge, Tennessee, USA
  
  Funding: This manuscript has been authored by UT-Battelle, LLC, under Contract No. DE-AC0500OR22725 with the U.S. Department of Energy.
A bench­mark of su­per­con­duct­ing cav­ity mod­els against Time-of-Flight mea­sure­ments at the SNS linac is pre­sented. The su­per­con­duct­ing part of SNS linac (SCL) in­cludes 81 RF cav­i­ties that ac­cel­er­ates H− beam from 185.6 MeV to the final en­ergy of 1 GeV. Dur­ing the op­er­a­tion some of cav­i­ties can be­come un­sta­ble, and its am­pli­tudes should be re­duced, or they should be com­pletely switched off. In this case, the SCL is re­tuned by using a linac sim­u­la­tion code. This sim­u­la­tion tool relay on an ac­cu­racy of the su­per­con­duct­ing cav­ity model. This paper de­scribes the com­par­i­son of the mea­sured beam ac­cel­er­a­tion by one of the SCL cav­i­ties and sim­u­la­tions of this process. Dif­fer­ent cav­ity mod­els are used in sim­u­la­tions. The sub­ject of this study is lim­ited to the lon­gi­tu­di­nal beam dy­nam­ics, so no ef­fects on trans­verse beam char­ac­ter­is­tics have been con­sid­ered. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB203  
About • paper received ※ 14 May 2021       paper accepted ※ 20 May 2021       issue date ※ 28 August 2021  
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MOPAB206 The RF Parameters of Heavy Ions Linac DTL, rfq, linac, MEBT 679
 
  • A. Sitnikov, G. Kropachev, T. Kulevoy, D.N. Selesnev, A.I. Semennikov
    ITEP, Moscow, Russia
  • M.L. Smetanin, A.V. Telnov, N.V. Zavyalov
    VNIIEF, Sarov, Russia
  
  The new linac for A/Z = 8, out­put en­ergy 4 MeV/u and 3 mA cur­rent is under de­vel­op­ment at NRC "Kur­cha­tov In­sti­tute"-ITEP. The linac con­sists of Ra­dio-Fre­quency Quadru­pole (RFQ) with op­er­at­ing fre­quency 40 MHz and two sec­tions of Drift Tube Linac (DTL) with op­er­at­ing fre­quency 80 and 160 MHz, cor­re­spon­dently. Both DTL has a mod­u­lar struc­ture and con­sists of sep­a­rated in­di­vid­u­ally phased res­onators with fo­cus­ing mag­netic quadrupoles lo­cated be­tween the cav­i­ties. The DTL1 is based on the quar­ter-wave res­onators mean­while DTL2 is based on IH 5-gap res­onators. The 6D beam match­ing be­tween RFQ and DTLs is pro­vided by mag­netic quadru­pole lenses and 2-gaps RF-bunch­ers. The paper pre­sents re­sults of the ra­dio-fre­quency (RF) de­sign of linac ac­cel­er­at­ing struc­tures.  
poster icon Poster MOPAB206 [0.559 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB206  
About • paper received ※ 14 May 2021       paper accepted ※ 01 July 2021       issue date ※ 28 August 2021  
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MOPAB208 LLRF Measurements and Cu-plating at the First-of-Series Cavity Section of the Alvarez 2.0 at GSI DTL, operation, simulation, vacuum 686
 
  • M. Heilmann, T. Dettinger, X. Du, L. Groening, S. Mickat, A. Rubin
    GSI, Darmstadt, Germany
  
  The Al­varez 2.0 will re­place the ex­ist­ing post-strip­per DTL of the GSI UNI­LAC. Today’s GSI com­prises the UNI­LAC and the syn­chro­tron SIS18 and is going to serve as the in­jec­tor chain for the Fa­cil­ity of An­tipro­ton and Ion Re­search (FAIR). The new Al­varez-type DTL is op­er­ated at 108.4 MHz pro­vid­ing ac­cel­er­a­tion from 1.4 MeV/u to 11.4 MeV/u along a total length of 55 me­ters. The first-of-se­ries (FoS) cav­ity sec­tion has 12 RF-gaps along a total length of 1.9 m. It is the first cav­ity sec­tion of the new DTL. All main com­po­nents were de­liv­ered in 2019, fol­lowed by suc­cess­ful SAT and in­stal­la­tion of the 11 drift tubes and cop­per-plat­ing. Com­ple­tion of first low level RF-mea­sure­ments prior to cop­per plat­ing and the sub­se­quent plat­ing are major pro­ject mile­stones. These pro­ceed­ings re­port on the re­sults and com­pares them to sim­u­la­tion using CST Mi­crowave Stu­dio.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB208  
About • paper received ※ 18 May 2021       paper accepted ※ 31 May 2021       issue date ※ 23 August 2021  
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MOPAB209 Commissioning of SANAEM RFQ Accelerator rfq, vacuum, plasma, proton 690
 
  • B. Yasatekin, A. Alacakir, A.S. Bolukdemir, I. Kilic, Y. Olgac
    TENMAK-NUKEN, Ankara, Turkey
  • E. Cicek
    KEK, Ibaraki, Japan
  • E. Cosgun
    UNIST, Ulsan, Republic of Korea
  
  The for­mer SANAEM RFQ is up­graded with a newly man­u­fac­tured cav­ity, made of oxy­gen-free cop­per (OFC), hav­ing the ca­pa­bil­ity of ac­cel­er­at­ing pro­tons from 20 keV to 1.3 MeV. In the as­sem­bling of cav­ity vanes, flanges, etc., in­dium wire is pre­ferred over the braz­ing process pro­vid­ing a more flex­i­ble and easy method for vac­uum seal­ing. After as­sem­bling the cav­ity, argon plasma clean­ing is per­formed for the final clean­ing and RF pre-con­di­tion­ing. Vac­uum tests re­vealed that lev­els of 2·10-7 mbar could be achieved quite eas­ily. RF power con­di­tion­ing of the RFQ cav­ity is suc­cess­fully com­pleted with the ob­ser­va­tion of quite few sparks. In the com­mis­sion­ing tests with the pro­ton beam, a mag­netic an­a­lyzer is used to mea­sure the en­ergy of the par­ti­cles. This paper pre­sents the strat­egy and the re­sults con­cern­ing the com­mis­sion­ing of the pro­ton beam with spe­cial em­pha­sis on the RFQ cav­ity.  
poster icon Poster MOPAB209 [5.076 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB209  
About • paper received ※ 19 May 2021       paper accepted ※ 14 June 2021       issue date ※ 29 August 2021  
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MOPAB210 High-Gradient Booster for Enhanced Proton Radiography at LANSCE linac, booster, proton, focusing 693
 
  • S.S. Kurennoy, Y.K. Batygin
    LANL, Los Alamos, New Mexico, USA
  
  In­creas­ing en­ergy of pro­ton beam at LAN­SCE from 800 MeV to 3 GeV im­proves ra­di­og­ra­phy res­o­lu­tion ~10 times. We pro­pose ac­com­plish­ing this en­ergy boost with a com­pact cost-ef­fec­tive linac based on cryo-cooled nor­mal con­duct­ing high-gra­di­ent RF ac­cel­er­at­ing struc­tures. High-gra­di­ent struc­tures ex­ceed­ing 100 MV/m have been de­vel­oped for elec­tron ac­cel­er­a­tion and op­er­ate with short RF pulse lengths below 1 us. Though such pa­ra­me­ters are un­usual for typ­i­cal pro­ton linacs, they fit per­fectly for pro­ton ra­di­og­ra­phy (pRad) ap­pli­ca­tions. The pRad lim­its con­tigu­ous trains of beam mi­cro-pulses to less than 80 ns to pre­vent blur in im­ages. For a com­pact pRad booster at LAN­SCE, we de­velop a staged de­sign: a short sec­tion to cap­ture and com­press the 800-MeV pro­ton beam fol­lowed by the main high-gra­di­ent linac. Our beam dy­nam­ics study ad­dresses the beam mag­netic fo­cus­ing and min­i­miz­ing its en­ergy spread, which are chal­leng­ing in high-gra­di­ent struc­tures but very im­por­tant for suc­cess­ful pRad op­er­a­tion.  
poster icon Poster MOPAB210 [0.809 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB210  
About • paper received ※ 10 May 2021       paper accepted ※ 17 August 2021       issue date ※ 23 August 2021  
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MOPAB211 Beam Coupling Impedances of Ferrite-Loaded Cavities: Calculations and Measurements impedance, dipole, resonance, coupling 696
 
  • S.S. Kurennoy, R.C. McCrady
    LANL, Los Alamos, New Mexico, USA
  
  We have de­vel­oped an ef­fi­cient method of cal­cu­lat­ing im­ped­ances in cav­i­ties with dis­per­sive fer­rite dampers. The fer­rite dis­per­sive prop­er­ties in the fre­quency range of in­ter­est are fit­ted in CST, which al­lows using both wake­field and lossy eigen­mode solvers. A sim­ple test cav­ity with or with­out fer­rite in­serts is ex­plored both nu­mer­i­cally and ex­per­i­men­tally. The res­o­nance fre­quen­cies and beam cou­pling im­ped­ances at cav­ity res­o­nances are cal­cu­lated with CST to un­der­stand the mode struc­ture. The cav­ity trans­verse cou­pling im­ped­ances are also mea­sured on a test stand using a two-wire method. We com­pare re­sults of im­ped­ance cal­cu­la­tions and mea­sure­ments for a few dif­fer­ent con­fig­u­ra­tions, with and with­out fer­rites, to en­sure a com­plete un­der­stand­ing of the cav­ity res­o­nances and their damp­ing with fer­rite. These re­sults are im­por­tant to pro­vide ad­e­quate damp­ing of un­de­sired trans­verse modes in in­duc­tion-linac cells.  
poster icon Poster MOPAB211 [1.105 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB211  
About • paper received ※ 10 May 2021       paper accepted ※ 21 May 2021       issue date ※ 19 August 2021  
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MOPAB232 Observation of Polarization-Dependent Changes in Higher-Order Mode Responses as a Function of Transverse Beam Position in Tesla-Type Cavities at FAST HOM, electron, dipole, cryomodule 756
 
  • R.M. Thurman-Keup, D.R. Edstrom, A.H. Lumpkin, P.S. Prieto, J. Ruan
    Fermilab, Batavia, Illinois, USA
  • J.A. Diaz Cruz
    UNM-ECE, Albuquerque, USA
  • J.A. Diaz Cruz, B.T. Jacobson, J.P. Sikora, F. Zhou
    SLAC, Menlo Park, California, USA
  
  Funding: FNAL supported by U.S. Department of Energy, Office of Science, under contract DE-AC02-07CH11359. SLAC supported by U.S. Department of Energy, Office of Science, under contract DE-AC02-76SF00515.
Higher-or­der modes (HOMs) in su­per­con­duct­ing rf cav­i­ties pre­sent prob­lems for an elec­tron bunch tra­vers­ing the cav­ity in the form of long-range wake­fields from pre­vi­ous bunches. These may di­lute the emit­tance of the macropulse av­er­age, es­pe­cially with low emit­tance beams at fa­cil­i­ties such as the Eu­ro­pean X-ray Free-elec­tron Laser (XFEL) and the up­graded Linac Co­her­ent Light Source (LCLS-II). Here we pre­sent ob­ser­va­tions of HOMs dri­ven by the beam at the Fer­mi­lab Ac­cel­er­a­tor Sci­ence and Tech­nol­ogy (FAST) fa­cil­ity. The FAST fa­cil­ity fea­tures two in­de­pen­dent TESLA-type cav­i­ties (CC1 and CC2) after a pho­to­cath­ode rf gun fol­lowed by an 8-cav­ity cry­omod­ule. The HOM sig­nals were ac­quired from cav­i­ties using band­pass fil­ters of 1.75 ± 0.15 GHz, 2.5 ± 0.2 GHz, and 3.25 ± 0.2 GHz and recorded using an 8-GHz, 20 GSa/s os­cil­lo­scope. The fre­quency res­o­lu­tion ob­tained is suf­fi­cient to sep­a­rate po­lar­iza­tion com­po­nents of many of the HOMs. These HOM sig­nals were cap­tured from CC1 and cav­i­ties 1 and 8 of the cry­omod­ule for var­i­ous ini­tial tra­jec­to­ries through the cav­i­ties, and we ob­serve cor­re­la­tions be­tween tra­jec­tory, HOM sig­nals, and which po­lar­iza­tion com­po­nent of a mode is af­fected. 		 
poster icon Poster MOPAB232 [2.144 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB232  
About • paper received ※ 20 May 2021       paper accepted ※ 25 May 2021       issue date ※ 28 August 2021  
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MOPAB236 Ion Beam Dynamics in Linac-100 Facility at Jinr linac, acceleration, emittance, rfq 767
 
  • S.M. Polozov, V.S. Dyubkov, Y. Lozeev, T.A. Lozeeva, A.V. Samoshin
    MEPhI, Moscow, Russia
  
  The heavy-ion linac LINAC-100 is a su­per­con­duct­ing dri­ver-ac­cel­er­a­tor pro­posed as one of the prospec­tive pro­jects at JINR. Its goal is to ac­cel­er­ate pri­mary sta­ble iso­tope CW high-in­ten­sity beams to en­er­gies up to 100 MeV/u*. This linac is dis­cussed as the first stage of a new rare iso­tope fa­cil­ity DE­R­ICA (Dubna Elec­tron-Ra­dioac­tive Ion Col­lider fA­cil­ity), being under de­vel­op­ment at JINR since 2017**. LINAC-100 is sup­posed to work with a wide range of beams with A/Z 3.5/7, Ura­nium U34+ being the heav­i­est. Its con­cept has un­der­gone many changes, mostly con­sid­er­ing strip­ping cells to in­crease ac­cel­er­a­tor ef­fi­ciency. Dur­ing the lat­est in­ves­ti­ga­tions of var­i­ous strip­ping cells [***, ****], Ura­nium beam strip­ping at the en­ergy 10 MeV/u and uti­liz­ing three ad­ja­cent charge states 59-61+ re­sulted in 60% out­put beam in­ten­sity preser­va­tion (or 30 pA over­all out­put cur­rent). The cur­rent lay­out of the LINAC-100 is the fol­low­ing: one or two (sep­a­rately for light and heavy ions) nor­mal con­duct­ing front-end linacs, gas strip­per cell at 10 MeV/u, and the SC sec­tion. In this paper three charge state Ura­nium beam dy­nam­ics in the cur­rent ver­sion of SC LINAC-100 sec­tion is pre­sented.
*S Polozov 2020 PhysScr 95 084006
**A S Fomichev Phys Usp 62(7) 675-690 2019
***Tolstikhina I 2018 Basic At Int of Acc H Ions in Matter 98 1
**** W Barth J Phys Conf Ser 1350:012096 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB236  
About • paper received ※ 20 May 2021       paper accepted ※ 13 August 2021       issue date ※ 17 August 2021  
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MOPAB247 Multipacting Studies for the JAEA-ADS Five-Cell Elliptical Superconducting RF Cavities multipactoring, electron, SRF, simulation 793
 
  • B. Yee-Rendón, Y. Kondo, F.M. Maekawa, S.I. Meigo, J. Tamura
    JAEA/J-PARC, Tokai-mura, Japan
  • E. Cicek
    KEK, Ibaraki, Japan
  
  The Five-cell El­lip­ti­cal Su­per­con­duct­ing Ra­dio-Fre­quency Cav­i­ties (SRFC) pro­vide the final ac­cel­er­a­tion in the JAEA-ADS linac (from 208 MeV to 1.5 GeV); thus, their per­for­mance is es­sen­tial for the suc­cess of the JAEA-ADS pro­ject. After their op­ti­miza­tion of the cav­ity geom­e­try to achieve a high ac­cel­er­a­tion gra­di­ent with lower elec­tro­mag­netic peaks, the next step in the R&D strat­egy is the ac­cu­rate es­ti­ma­tion of beam-cav­ity ef­fects which can af­fect the per­for­mance of the cav­i­ties. To this end, mul­ti­pact­ing stud­ies were de­vel­oped to in­ves­ti­gate its ef­fect in the cav­ity op­er­a­tion reg­i­men and find coun­ter­mea­sures. The re­sults of this study will help in the de­vel­op­ment of the SRFC mod­els and in the con­sol­i­da­tion of the JAEA-ADS pro­ject.  
poster icon Poster MOPAB247 [0.599 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB247  
About • paper received ※ 10 May 2021       paper accepted ※ 07 June 2021       issue date ※ 02 September 2021  
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MOPAB255 Demonstration of a Novel Longitudinal Phase Space Linearization Method without Higher Harmonics electron, gun, simulation, laser 805
 
  • R. Stark
    University of Hamburg, Hamburg, Germany
  • K. Flöttmann, M. Hachmann
    DESY, Hamburg, Germany
  • F.J. Grüner
    Center for Free-Electron Laser Science, Universität Hamburg, Hamburg, Germany
  • B. Zeitler
    CFEL, Hamburg, Germany
  
  Non­lin­ear cor­re­la­tions in the lon­gi­tu­di­nal phase space of elec­tron bunches can be a de­ci­sive lim­i­ta­tion to the achiev­able bunch length com­pres­sion and at­tain­abil­ity of small en­ergy spreads. To over­come the re­stric­tions im­posed by non­lin­ear dis­tor­tions, the lon­gi­tu­di­nal phase space dis­tri­b­u­tion must be lin­earized. Pre­vi­ously, a novel lin­eariza­tion pro­ce­dure based on the con­trolled ex­pan­sion of the bunch be­tween two radio fre­quency cav­i­ties op­er­ated at the same fun­da­men­tal fre­quency has been pre­sented in *. A demon­stra­tion of this lin­eariza­tion method is pre­sented in this work.
*B. Zeitler, K. Floettmann, and F. Grüner, "Linearization of the longitudinal phase space without higher harmonic field," Phys. Rev. ST Accel. Beams, vol. 18, p. 120102, 2015. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB255  
About • paper received ※ 18 May 2021       paper accepted ※ 02 June 2021       issue date ※ 12 August 2021  
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MOPAB289 Machine Learning Training for HOM reduction and Emittance Preservation in a TESLA-type Cryomodule at FAST HOM, emittance, electron, controls 916
 
  • J.A. Diaz Cruz
    UNM-ECE, Albuquerque, USA
  • J.A. Diaz Cruz, A.L. Edelen, B.T. Jacobson, J.P. Sikora
    SLAC, Menlo Park, California, USA
  • D.R. Edstrom, A.H. Lumpkin, R.M. Thurman-Keup
    Fermilab, Batavia, Illinois, USA
  
  Low emit­tance elec­tron beams are of high im­por­tance at fa­cil­i­ties like the LCLS-II at SLAC. Emit­tance di­lu­tion ef­fects due to off-axis beam trans­port for a TESLA-type cry­omod­ule (CM) have been shown at the Fer­mi­lab Ac­cel­er­a­tor Sci­ence and Tech­nol­ogy fa­cil­ity. The re­sults showed the cor­re­la­tion be­tween the elec­tron beam-in­duced cav­ity high-or­der modes (HOMs) and sub­macropulse cen­troid slew­ing and os­cil­la­tion down­stream of the CM. Mit­i­ga­tion of emit­tance di­lu­tion can be achieved by re­duc­ing the HOM sig­nals and the vari­ances in the sub­macropulse beam po­si­tions down­stream of the CM. Here we pre­sent a Ma­chine Learn­ing based op­ti­miza­tion and model con­struc­tion for HOM sig­nal level re­duc­tion using Neural Net­works and Gauss­ian Processes. To gather train­ing data we per­formed ex­per­i­ments using sin­gle bunch and 50 bunch elec­tron beams with charges up to 125 pC/b. We mea­sured HOM sig­nals of all cav­i­ties and beam po­si­tion with a set of BPMs down­stream of the CM. The beam tra­jec­tory was changed using V/H125 cor­rec­tor set lo­cated up­stream of the CM. The re­sults pre­sented here will in­form the LCLS-II in­jec­tor com­mis­sion­ing and will serve as a pro­to­type for HOM re­duc­tion and emit­tance preser­va­tion.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB289  
About • paper received ※ 19 May 2021       paper accepted ※ 09 June 2021       issue date ※ 24 August 2021  
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MOPAB290 Machine Learning-Based LLRF and Resonance Control of Superconducting Cavities controls, LLRF, simulation, SRF 920
 
  • J.A. Diaz Cruz, S. Biedron, M. Martínez-Ramón
    UNM-ECE, Albuquerque, USA
  • J.A. Diaz Cruz
    SLAC, Menlo Park, California, USA
  • R. Pirayesh
    UNM-ME, Albuquerque, New Mexico, USA
  • S. Sosa
    ODU, Norfolk, Virginia, USA
  
  Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics, under award number DE-SC0019468.
Su­per­con­duct­ing radio fre­quency (SRF) cav­i­ties with high loaded qual­ity fac­tors that op­er­ate in con­tin­u­ous wave (CW) and low beam load­ing are sen­si­tive to mi­cro­phon­ics-in­duced de­tun­ing. Cav­ity de­tun­ing can re­sult in an in­crease of op­er­a­tional power and/or in a cav­ity quench. Such SRF cav­i­ties have band­widths on the order of 10 Hz and de­tun­ing re­quire­ments can be as tight as 10 Hz. Pas­sive meth­ods to mit­i­gate vi­bra­tion sources and their im­pact in the cry­omod­ule/cav­ity en­vi­ron­ment are widely used. Ac­tive res­o­nance con­trol tech­niques that use step­per mo­tors and piezo­elec­tric ac­tu­a­tors to tune the cav­ity res­o­nance fre­quency by com­pen­sat­ing for mi­cro­phon­ics de­tun­ing have been in­ves­ti­gated. These con­trol tech­niques could be fur­ther im­proved by ap­ply­ing Ma­chine Learn­ing (ML), which has shown promis­ing re­sults in other par­ti­cle ac­cel­er­a­tor con­trol sys­tems. In this paper, we de­scribe a Low-level RF (LLRF) and res­o­nance con­trol sys­tem based on ML meth­ods that op­ti­mally and adap­tively tunes the con­trol pa­ra­me­ters. We pre­sent sim­u­la­tions and test re­sults ob­tained using a low power test bench with a cav­ity em­u­la­tor. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB290  
About • paper received ※ 03 June 2021       paper accepted ※ 11 June 2021       issue date ※ 27 August 2021  
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MOPAB291 Design of Cavity BPM Pickup for EuPRAXIA@SPARC_LAB coupling, GUI, pick-up, simulation 924
 
  • Sh. Bilanishvili
    INFN/LNF, Frascati (Roma), Italy
  
  EuPRAXIA@​SPARC_​LAB will make avail­able at LNF a unique com­bi­na­tion of­fer­ing three dif­fer­ent op­tions. A high-bright­ness elec­tron beam with 1 GeV en­ergy gen­er­ated in a novel X-band RF linac; A PW-class laser sys­tem, and a com­pact light-source di­rectly dri­ven by a plasma ac­cel­er­a­tor*. Plasma and con­ven­tional RF linac dri­ven FEL pro­vide beam with pa­ra­me­ters of 30- 200pC charge range, 10-100Hz rep­e­ti­tion rate, and 1 GeV elec­tron en­ergy**. The con­trol of the charge and the tra­jec­tory mon­i­tor­ing at a few pC and a few um is manda­tory in this ma­chine. Par­tic­u­larly in the plasma in­ter­ac­tion re­gion, where the pickup res­o­lu­tion under 1 um is re­quired. As a pos­si­ble so­lu­tion, a cav­ity beam po­si­tion mon­i­tor (cBPM) is pro­posed. A pro­to­type in the C-band fre­quency range has been de­signed. The pickup was op­ti­mized for low charge and sin­gle-shot bunches. The poster pre­sents the process to achieve the re­quired spec­i­fi­ca­tions. The sim­u­la­tions were per­formed to study RF prop­er­ties and the elec­tro­mag­netic re­sponse of the de­vice. Fi­nally, the over­all per­for­mance of the pickup is dis­cussed, and the­o­ret­i­cal res­o­lu­tion is ap­prox­i­mated.
* https://www.researchgate.net/publication/335459394FromSPARCLABtoEuPRAXIASPARC_LAB
**http://www.lnf.infn.it/sis/preprint/detail-new.php?id=5416 		 
poster icon Poster MOPAB291 [16.718 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB291  
About • paper received ※ 19 May 2021       paper accepted ※ 09 June 2021       issue date ※ 14 August 2021  
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MOPAB322 Electronics for Bead-pull Measurement of Radio Frequency Accelerating Structures in LEHIPA controls, software, rfq, interface 993
 
  • S. Rosily, S. Krishnagopal
    Homi Bhbha National Institute (HBNI), DAE, Mumbai, India
  • S. Krishnagopal, S. Singh
    BARC, Mumbai, India
  
  For car­ry­ing out bead-pull char­ac­ter­i­sa­tion of RFQ and DTL at the Low En­ergy High In­ten­sity Pro­ton Ac­cel­er­a­tor of BARC, a con­troller for si­mul­ta­ne­ous mo­tion of 64 axis, tuners or post cou­plers, was de­vel­oped. Also, a bead mo­tion con­troller with in­te­grated phase mea­sure­ment sen­sor was de­vel­oped. The paper dis­cusses the re­quire­ments of the sys­tem, the ar­chi­tec­ture of the con­trol sys­tems, op­er­a­tion and re­sults. The re­sults ob­tained from the sen­sor was com­pared to that ob­tained using an in­de­pen­dent USB VNA. The ad­van­tages of the sys­tem es­pe­cially with ad­di­tion of in­ter­nal phase mea­sure­ment sen­sor in­clud­ing min­imis­ing po­si­tion error, flex­i­bil­ity in bead­pull to se­lec­tively in­crease res­o­lu­tion at spec­i­fied lo­ca­tions and ease of im­ple­ment­ing auto-tun­ing al­go­rithms are dis­cussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB322  
About • paper received ※ 20 May 2021       paper accepted ※ 24 May 2021       issue date ※ 21 August 2021  
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MOPAB323 Commissioning of the LCLS-II Prototype HOM Detectors with Tesla-Type Cavities at Fast HOM, electron, cryomodule, detector 996
 
  • J.P. Sikora, J.A. Diaz Cruz, B.T. Jacobson
    SLAC, Menlo Park, California, USA
  • J.A. Diaz Cruz
    UNM-ECE, Albuquerque, USA
  • D.R. Edstrom, A.H. Lumpkin, P.S. Prieto, J. Ruan, R.M. Thurman-Keup
    Fermilab, Batavia, Illinois, USA
  
  Funding: *Work supported by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy. **Work supported by the U.S. Department of Energy, contract DE-AC02-76SF00515.
Ex­per­i­ments at the Fer­mi­lab Ac­cel­er­a­tor Sci­ence and Tech­nol­ogy* (FAST) fa­cil­ity de­tected elec­tron beam-in­duced high order mode (HOM) sig­nals from Tesla su­per­con­duct­ing cav­i­ties. This paper de­scribes some of the sig­nal de­tec­tion hard­ware used in this ex­per­i­ment, as well as mea­sure­ments of the HOM sig­nal mag­ni­tude ver­sus beam tra­jec­tory. These mea­sure­ments were made both with a sin­gle bunch and with a train of 50 bunches at bunch charges from 400 pC/b down to 10 pC/b. The de­tec­tion hard­ware is de­signed for use with the Tesla su­per­con­duct­ing cav­i­ties of LCLS-II at SLAC** and is based on a pro­to­type al­ready in use at Fer­mi­lab. The HOM sig­nal passes through a band­pass fil­ter that is cen­tered on sev­eral cav­ity di­pole modes and a zero bias Schot­tky diode de­tects its mag­ni­tude. Di­rect com­par­isons were made be­tween the FNAL chas­sis and the SLAC pro­to­type for iden­ti­cal beam steer­ing con­di­tions. To sup­port mea­sure­ments with bunch charges as low as 10 pC, the SLAC de­tec­tor has RF am­pli­fi­ca­tion be­tween the band­pass fil­ter and the diode de­tec­tor. With this hard­ware, us­able HOM sig­nal mea­sure­ments are ob­tained with a sin­gle bunch of 10 pC in cry­omod­ule cav­i­ties as will be needed for LCLS-II. 		 
poster icon Poster MOPAB323 [2.076 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB323  
About • paper received ※ 17 May 2021       paper accepted ※ 07 June 2021       issue date ※ 25 August 2021  
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MOPAB329 Operations of Copper Cavities at Cryogenic Temperatures coupling, linac, cryogenics, ECR 1020
 
  • H. Wang, U. Ratzinger, M. Schuett
    IAP, Frankfurt am Main, Germany
  
  How the anom­alous skin ef­fect by cop­per af­fects the ef­fi­ciency of cop­per- cav­i­ties will be stud­ied in the ex­per­i­ment, es­pe­cially at lower tem­per­a­tures. The ac­cu­rate qual­ity fac­tor Q and res­o­nant fre­quency of three coax­ial cav­i­ties will be mea­sured over the tem­per­a­ture range from 300 to 22 K. The three coax­ial cav­i­ties have the same struc­ture, but dif­fer­ent lengths, which cor­re­spond to res­o­nant fre­quen­cies: around 100 MHz, 220 MHz and 340 MHz. The mo­ti­va­tion is to check the fea­si­bil­ity of an ef­fi­cient pulsed, liq­uid ni­tro­gen cooled ion linac.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB329  
About • paper received ※ 19 May 2021       paper accepted ※ 07 June 2021       issue date ※ 24 August 2021  
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MOPAB330 Production and Performance Evaluation of a Compact Deflecting Cavity to Measure the Bunch Length in the cERL resonance, vacuum, coupling, impedance 1023
 
  • D. Naito, Y. Honda, T. Miyajima, N. Yamamoto
    KEK, Ibaraki, Japan
  
  At the KEK com­pact en­ergy re­cov­ery linac, we try to gen­er­ate an in­frared free-elec­tron laser (FEL). To gen­er­ate the FEL, an elec­tron bunch should be com­pressed along the lon­gi­tu­di­nal di­rec­tion. The mea­sure­ment of the bunch length is key to op­ti­mize the bunch com­pres­sion. We plan to mea­sure the bunch length by de­flect­ing cav­i­ties in the burst mode. The de­flect­ing cav­i­ties are re­quired to be a time res­o­lu­tion of 33 fs in order to not only mea­sure the bunch length but also re­solve the struc­ture in­side the elec­tron bunch. To achieve the re­quire­ment, we de­vel­oped a c-band cav­ity whose RF input port is com­pact. The de­flect­ing cav­ity is a sin­gle cell and nor­mal con­duct­ing cav­ity. The de­flec­tion mode of the cav­ity is TM110. The 12 cav­i­ties will be lo­cated at the exit of un­du­la­tors. In this pre­sen­ta­tion, we ex­plain the de­sign of our cav­ity and re­port the pro­duc­tion of the first cav­ity. We also re­port the eval­u­a­tion of the res­o­nance fre­quency, the un­loaded Q and the ex­ter­nal Q of the cav­ity. From the mea­sure­ments and sim­u­la­tions, the R/Q is es­ti­mated to be 1 mega orms. The time res­o­lu­tion of the cav­ity is ex­pected to be 400 fs when the input RF power is 1 kW and the beam en­ergy is 20 MeV.  
poster icon Poster MOPAB330 [12.920 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB330  
About • paper received ※ 12 May 2021       paper accepted ※ 08 June 2021       issue date ※ 15 August 2021  
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MOPAB331 Design Consideration of a Longitudinal Kicker Cavity for Compensating Transient Beam Loading Effect in Synchrotron Light Sources kicker, resonance, coupling, impedance 1027
 
  • D. Naito, S. Sakanaka, T. Takahashi, N. Yamamoto
    KEK, Ibaraki, Japan
  • T. Yamaguchi
    Sokendai, Ibaraki, Japan
  
  In ul­tra-low-emit­tance syn­chro­tron light sources, bunch-length­en­ing using the com­bi­na­tion of main and har­monic cav­i­ties is lim­ited by the tran­sient beam-load­ing (TBL) ef­fect which is caused by gaps in the fill pat­tern. To man­age this ef­fect, we pro­posed a TBL com­pen­sa­tion tech­nique using a wide-band lon­gi­tu­di­nal kicker cav­ity*. In the fu­ture KEK-LS stor­age ring, for ex­am­ple, the kicker cav­ity should pro­vide a com­pen­sa­tion volt­age of 50 kV with a -3dB band­width (BW) of about 5 MHz, as well as its higher-or­der modes (HOM) should be damped suf­fi­ciently. In this pre­sen­ta­tion, we re­port our con­cep­tual de­sign of the kicker cav­ity. We em­ployed the sin­gle-mode (SM) cav­ity con­cept so that harm­ful HOMs are dumped by rf ab­sorbers on the beam pipes. The dis­tinc­tive fea­ture of the SM cav­ity is its sim­ple struc­ture since it has no HOM damper on the cav­ity. An­other fea­ture is its low R/Q by which the TBL ef­fect in the kicker cav­ity it­self can be re­duced sig­nif­i­cantly. We em­ployed a fre­quency of 1.5 GHz (third-har­monic) and R/Q of 60 orms through op­ti­miza­tions. Using this kicker cav­ity with a dou­ble rf sys­tem, a bunch length­en­ing by a fac­tor of 4.3 (i.e., 40.9 ps) is ex­pected for the KEK-LS case.
* N.Yamamoto et al., Phys. Rrev. Acc. Beams 21, 012001 (2018) 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB331  
About • paper received ※ 19 May 2021       paper accepted ※ 11 June 2021       issue date ※ 10 August 2021  
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MOPAB332 Design of 4th Harmonic RF Cavities for ESRF-EBS HOM, SRF, impedance, coupling 1031
 
  • A. D’Elia, J. Jacob, V. Serrière, X.W. Zhu
    ESRF, Grenoble, France
  
  Funding: European Union’s Horizon 2020 research and innovation program under grant #871072
An ac­tive 4th har­monic RF sys­tem for bunch length­en­ing is under study at the ESRF to im­prove the per­for­mance of the new EBS stor­age ring, mainly for few bunch op­er­a­tion with high cur­rents per bunch, by re­duc­ing Tou­schek and in­tra­beam scat­ter­ing, thereby in­creas­ing the life­time and lim­it­ing the emit­tance growth. It will also re­duce im­ped­ance heat­ing of the vac­uum cham­bers. The 4th Har­monic 1.41 GHz nor­mal con­duct­ing cav­ity de­sign takes in­spi­ra­tion from the KEK idea of using a TM020 mode ex­hibit­ing a re­duced R/Q but a higher un­loaded Q with re­spect to TM010. We pro­pose to use mul­ti­cell cav­i­ties for their com­pact­ness, the re­duced num­ber of re­quired an­cil­lar­ies and the ease of con­trol for a re­duced num­ber of cav­i­ties. The draw­back is the com­plex­ity of the model and the ne­ces­sity to damp the lower order TM010 mode (LOM) as well as the higher order modes (HOM). The RF de­sign of a 4th har­monic mul­ti­cell damped cav­ity will be pre­sented. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB332  
About • paper received ※ 19 May 2021       paper accepted ※ 17 August 2021       issue date ※ 18 August 2021  
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MOPAB333 ESRF-EBS 352 MHz HOM Damped RF Cavities SRF, impedance, HOM, MMI 1034
 
  • A. D’Elia, J. Jacob, V. Serrière
    ESRF, Grenoble, France
  
  For the new ESRF-EBS Stor­age Ring (SR), HOM damped RF cav­i­ties were needed to cope with the re­duced thresh­olds for Lon­gi­tu­di­nal Cou­pled Bunch In­sta­bil­i­ties (LCBI). The 352 MHz cav­i­ties were de­signed at the ESRF based on an im­proved ver­sion of the 500 MHz EU/ALBA/BESSY struc­tures. A short de­scrip­tion of the cav­ity de­sign will be pre­sented as well as an overview of the fab­ri­ca­tion, the prepa­ra­tion and the per­for­mance of 13 such cav­i­ties for the ESRF-EBS SR. A study of the im­ped­ance of a whole cav­ity equipped with its an­cil­lar­ies (HOM ab­sorbers, ion pump and tuner) will be pre­sented. One of the three HOM ab­sorbers, the smaller one on top of the cav­ity, was fi­nally not in­stalled on the ma­chine. The rea­sons and a de­tailed analy­sis in terms of HOM im­ped­ances that jus­ti­fies this choice will be re­ported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB333  
About • paper received ※ 19 May 2021       paper accepted ※ 07 June 2021       issue date ※ 23 August 2021  
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MOPAB334 Status and Recent Development of FAIR Ring RF Systems LLRF, power-supply, operation, status 1037
 
  • U. Laier, R. Balß, C. Christoph, M. Frey, P. Hülsmann, H. Klingbeil, H.G. König, D.E.M. Lens, J.S. Schmidt, A. Stuhl, K.G. Thomin, T. Winnefeld
    GSI, Darmstadt, Germany
  • H. Klingbeil
    TEMF, TU Darmstadt, Darmstadt, Germany
  
  Funding: GSI Helmholtzzentrum für Schwerionenforschung GmbH
Five dif­fer­ent Ring RF Sys­tems are re­quired for the op­er­a­tion of FAIR (Fa­cil­ity for An­tipro­ton and Ion Re­search). These sys­tems have to op­er­ate at fre­quen­cies be­tween 310 kHz and 3.2 MHz, with gap volt­ages up to 40 kVp and duty cy­cles from 5·10-4 up to cw. All sys­tems will be re­al­ized using in­duc­tively loaded (fer­rite or mag­netic alloy) cav­i­ties dri­ven by tetrode-based am­pli­fiers fed by switch-mode power sup­plies. To sta­bi­lize the am­pli­tude, res­o­nance fre­quency and phase, ver­sa­tile dig­i­tal feed­back and feed­for­ward con­trol will be used. This con­tri­bu­tion will pre­sent the lat­est de­vel­op­ment on the power part and the LLRF of the four RF sys­tems of the SIS100 (SIS100 Ac­cel­er­a­tion, SIS100 Bunch Com­pres­sion, SIS100 Bar­rier Bucket and SIS100 Lon­gi­tu­di­nal Feed­back) as well as the CR De­buncher sys­tem which is part of the Col­lec­tor Ring. The progress of these sys­tems varies by a large de­gree. This note will give an overview re­gard­ing the sta­tus of the de­sign, pro­cure­ment, re­al­iza­tion, test­ing, op­ti­miza­tion, com­mis­sion­ing and prepa­ra­tion for in­stal­la­tion of these RF sys­tems. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB334  
About • paper received ※ 18 May 2021       paper accepted ※ 07 June 2021       issue date ※ 17 August 2021  
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MOPAB337 Design Study of the Spiral Buncher Cavities for the High Current Injector at IUAC linac, impedance, bunching, rfq 1048
 
  • S. Kedia, R. Ahuja, R. Mehta, C.P. Safvan
    IUAC, New Delhi, India
  
  Two high en­ergy beam trans­port (HEBT) cav­i­ties have been de­signed to pro­vide the lon­gi­tu­di­nal beam bunch­ing be­tween drift tube linac and su­per­con­duct­ing su­per-buncher of the su­per­con­duct­ing lin­ear (SC-LINAC) ac­cel­er­a­tor. The spi­ral type cav­i­ties were cho­sen over stan­dard quar­ter wave-type geom­e­try due to its higher shunt im­ped­ance. The TRACE-3D ion-op­ti­cal codes have been used to de­ter­mine the bunch­ing volt­age and phys­i­cal lo­ca­tion of the cav­i­ties. The two-gap RF cav­ity re­quires 80 kV/gap to pro­vide the lon­gi­tu­di­nal beam bunch­ing at the en­trance of the su­per­con­duct­ing buncher. The CST-MWS sim­u­la­tions were per­formed to de­sign the spi­ral type bunch­ing cav­i­ties. The var­i­ous pa­ra­me­ters in­clud­ing shunt im­ped­ance, qual­ity fac­tor, av­er­age ac­cel­er­at­ing field, and total power loss were de­ter­mined using CST-MWS sim­u­la­tions. The ratio of drift tube ra­dius to the gap was op­ti­mized to achieve the max­i­mum ef­fec­tive elec­tric field with min­i­mum field pen­e­tra­tion within the gap. The Solid­Works soft­ware has been used to pre­pare a me­chan­i­cal model for the fab­ri­ca­tion.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB337  
About • paper received ※ 15 May 2021       paper accepted ※ 26 May 2021       issue date ※ 01 September 2021  
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MOPAB339 Design Of An X-band 3MeV Standing-wave Accelerating Structure with Nose-cone Structure Made From Two Halves coupling, impedance, electron, bunching 1051
 
  • F. Liu, H.B. Chen, J. Shi, C.-X. Tang, H. Zha
    TUB, Beijing, People’s Republic of China
  
  This work pre­sents an X-band 3MeV stand­ing-wave ac­cel­er­at­ing struc­ture with nose cones made from two halves. Milling two lon­gi­tu­di­nally split halves is one eco­nomic method to man­u­fac­ture ac­cel­er­at­ing struc­ture for de­crease of weld­ing, with in­creas­ing the dif­fi­culty in ma­chin­ing. This lin­ear ac­cel­er­a­tor in­cludes 4 buncher cav­i­ties and 4 ac­cel­er­at­ing cav­i­ties, and nose cone is ap­plied to achieve high shunt im­ped­ance. A tech­ni­cal pro­to­type is under fab­ri­ca­tion to bring two milled halves man­u­fac­ture way into prac­ti­cal ap­pli­ca­tion.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB339  
About • paper received ※ 19 May 2021       paper accepted ※ 26 May 2021       issue date ※ 17 August 2021  
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MOPAB341 First C-Band High Gradient Cavity Testing Results at LANL proton, GUI, operation, klystron 1057
 
  • E.I. Simakov, R.L. Fleming, D. Gorelov, T.A. Jankowski, M.F. Kirshner, J.W. Lewellen, J.D. Pizzolatto, M.E. Schneider, T. Tajima
    LANL, Los Alamos, New Mexico, USA
  • X. Lu, E.A. Nanni, S.G. Tantawi
    SLAC, Menlo Park, California, USA
  • M.E. Middendorf
    ANL, Lemont, Illinois, USA
  
  Funding: Los Alamos National Laboratory LDRD Program.
This poster will re­port the re­sults of high gra­di­ent test­ing of the two pro­ton β=0.5 C-band ac­cel­er­at­ing cav­i­ties. The cav­i­ties for pro­ton ac­cel­er­a­tion were fab­ri­cated at SLAC and tested at high gra­di­ent C-band ac­cel­er­a­tor test stand at LANL. One cav­ity was made of cop­per, and the sec­ond was made of a cop­per-sil­ver alloy. LANL test stand was con­structed around a 50 MW, 5.712 GHz Canon kly­stron and is ca­pa­ble to pro­vide power for con­di­tion­ing sin­gle cell ac­cel­er­at­ing cav­i­ties for op­er­a­tion at sur­face elec­tric fields up to 300 MV/m. These β=0.5 C-band cav­i­ties were the first two cav­i­ties tested on LANL C-band test stand. The pre­sen­ta­tion will re­port achieved gra­di­ents, break­down prob­a­bil­i­ties, and other char­ac­ter­is­tics mea­sured dur­ing the high power op­er­a­tion. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB341  
About • paper received ※ 19 May 2021       paper accepted ※ 25 May 2021       issue date ※ 15 August 2021  
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MOPAB342 Design, Fabrication, and Commissioning of the Mode Launchers for High Gradient C-Band Cavity Testing at LANL GUI, klystron, simulation, MMI 1060
 
  • E.I. Simakov, J.E. Acosta, D. Gorelov, M.F. Kirshner, J.W. Lewellen
    LANL, Los Alamos, New Mexico, USA
  • P. Borchard
    Dymenso LLC, San Francisco, USA
  • M.E. Schneider
    MSU, East Lansing, Michigan, USA
  
  Funding: Los Alamos National Laboratory LDRD Program.
This poster will re­port on the de­sign, fab­ri­ca­tion, and op­er­a­tion sta­tus of the new high gra­di­ent C-band TM01 mode launch­ers for the high gra­di­ent C-band test stand at LANL. Mod­ern ap­pli­ca­tions re­quire ac­cel­er­a­tors with op­ti­mized cost of con­struc­tion and op­er­a­tion, nat­u­rally call­ing for high-gra­di­ent ac­cel­er­a­tion. At LANL we com­mis­sioned a test stand pow­ered by a 50 MW, 5.712 GHz Canon kly­stron. The test is ca­pa­ble of con­di­tion­ing sin­gle cell ac­cel­er­at­ing cav­i­ties for op­er­a­tion at sur­face elec­tric fields up to 300 MV/m. The rf field is cou­pled into the cav­ity from a WR187 wave­guide through a mode launcher that con­verts the fun­da­men­tal mode of the rec­tan­gu­lar wave­guide into the TM01 mode of the cir­cu­lar wave­guide. Sev­eral de­signs for mode launch­ers were con­sid­ered and the final de­sign was cho­sen based on a com­pro­mise be­tween the field en­hance­ments, band­width, and sim­plic­ity and cost of fab­ri­ca­tion. Four mode launch­ers were fab­ri­cated and cold-tested. Two mode launch­ers with the best trans­mis­sion char­ac­ter­is­tics were in­stalled and con­di­tioned to high power. The pre­sen­ta­tion will re­port achieved gra­di­ents, break­down prob­a­bil­i­ties, and other char­ac­ter­is­tics mea­sured dur­ing op­er­a­tion. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB342  
About • paper received ※ 19 May 2021       paper accepted ※ 25 May 2021       issue date ※ 27 August 2021  
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MOPAB343 Optimization of the Parasitic-Mode Damping on the 1.5 GHz TM020-type Harmonic Cavity damping, impedance, coupling, simulation 1064
 
  • T. Yamaguchi
    Sokendai, Ibaraki, Japan
  • D. Naito, S. Sakanaka, T. Takahashi, N. Yamamoto
    KEK, Ibaraki, Japan
  
  Bunch-length­en­ing har­monic cav­ity is one of the es­sen­tial tools to mit­i­gate the in­tra­beam scat­ter­ing in the 4th-gen­er­a­tion syn­chro­tron light sources. For this pur­pose, we pro­posed a nor­mal-con­duct­ing 1.5 GHz har­monic cav­ity* of TM020-type**. Thanks to its low R/Q (68 ohms) and high un­loaded Q (34, 000), bunch gap tran­sient in the har­monic cav­ity can be re­duced to ~20% as com­pared to that in a typ­i­cal TM010 cav­ity. Fur­ther­more, harm­ful par­a­sitic modes in this cav­ity can be heav­ily damped by in­stalling fer­rites where no mag­netic fields of TM020-mode exist. How­ever, some of the par­a­sitic modes, e.g. TM021 and TM120 modes, are dif­fi­cult to damp be­cause their field pat­terns are sim­i­lar to that of the TM020 mode. To damp such modes ef­fec­tively, we op­ti­mized the cav­ity inner shape by tai­lor­ing the cur­va­ture at the cav­ity equa­tor, the shape of the nose cones, and in­tro­duc­ing "bumps" on the inner wall. Our goals of the cou­pling im­ped­ances are fxR < 2.4[kohm GHz] and RT < 23 kohm/m in the lon­gi­tu­di­nal and the trans­verse planes, re­spec­tively. As a re­sult of op­ti­miza­tion, we al­most achieved these goals. To con­firm our sim­u­la­tion re­sults, fab­ri­ca­tion of a low-power test cav­ity is in progress.
* N . Yamamoto et al., Phys. Rev. Acc. Beams 21, 012001 (2018).
** H. Ego et al., Proc. of the 11th Annual Meeting of Particle Accelerator Society of Japan (PASJ2014), MOOL14 (2014).
 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB343  
About • paper received ※ 19 May 2021       paper accepted ※ 26 May 2021       issue date ※ 27 August 2021  
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MOPAB344 Machine Learning Models for Breakdown Prediction in RF Cavities for Accelerators operation, network, vacuum, linac 1068
 
  • C. Obermair, A. Apollonio, T. Cartier-Michaud, N. Catalán Lasheras, L. Felsberger, W.L. Millar, W. Wuensch
    CERN, Geneva, Switzerland
  • C. Obermair, F. Pernkopf
    TUG, Graz, Austria
  
  Radio Fre­quency (RF) break­downs are one of the most preva­lent lim­its in RF cav­i­ties for par­ti­cle ac­cel­er­a­tors. Dur­ing a break­down, field en­hance­ment as­so­ci­ated with small de­for­ma­tions on the cav­ity sur­face re­sults in elec­tri­cal arcs. Such arcs de­grade a pass­ing beam and if they occur fre­quently, they can cause ir­repara­ble dam­age to the RF cav­ity sur­face. In this paper, we pro­pose a ma­chine learn­ing ap­proach to pre­dict the oc­cur­rence of break­downs in CERN’s Com­pact LIn­ear Col­lider (CLIC) ac­cel­er­at­ing struc­tures. We dis­cuss state-of-the-art al­go­rithms for data ex­plo­ration with un­su­per­vised ma­chine learn­ing, break­down pre­dic­tion with su­per­vised ma­chine learn­ing, and re­sult val­i­da­tion with Ex­plain­able-Ar­ti­fi­cial In­tel­li­gence (Ex­plain­able AI). By in­ter­pret­ing the model pa­ra­me­ters of var­i­ous ap­proaches, we go fur­ther in ad­dress­ing op­por­tu­ni­ties to elu­ci­date the physics of a break­down and im­prove ac­cel­er­a­tor re­li­a­bil­ity and op­er­a­tion.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB344  
About • paper received ※ 20 May 2021       paper accepted ※ 16 July 2021       issue date ※ 10 August 2021  
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MOPAB347 High Power Coupler Conditioning for bERLinPro Energy Recovery Linac Injector booster, vacuum, SRF, MMI 1080
 
  • A. Neumann, W. Anders, F. Göbel, A. Heugel, S. Klauke, J. Knobloch, M. Schuster, Y. Tamashevich
    HZB, Berlin, Germany
  
  Funding: The work is funded by the Helmholtz-Association, BMBF, the state of Berlin and HZB.
Helmholtz Zen­trum Berlin is cur­rently fi­nal­iz­ing the con­struc­tion of the demon­stra­tor En­ergy Re­cov­ery Linac bERLinPro *. The first part, which will be com­mis­sioned, will be the in­jec­tor con­sist­ing of a su­per­con­duct­ing RF (SRF) photo-in­jec­tor (Gun) and a Booster mod­ule made up of three two cell SRF cav­i­ties. For the lat­ter the 2.3 MeV beam from the gun needs to be ac­cel­er­ated to 6.5 MeV, whereas one Booster cav­ity will be op­er­ated in zero-cross­ing mode for bunch-short­en­ing. Thus, for the final stage with a 100 mA beam, the twin power cou­plers of the Booster cav­ity need to de­liver up to 120 kW in trav­el­ling con­ti­nous wave (CW) mode at 1.3 GHz each. To achieve that, a ded­i­cated cou­pler con­di­tion­ing setup was in­stalled and com­mis­sioned. Here, we will pre­sent the first con­di­tion­ing re­sults with the bERLinPro Booster fun­da­men­tal power cou­plers in pulsed and CW regime.
* M. Abo-Bakr et al., in Proc. 9th Int. Particle Accelerator Conf. (IPAC’18), Vancouver, BC, Canada, Apr. 4,, pp. 4127-4130, doi:10.18429/JACoW-IPAC2018-THPMF034 		 
poster icon Poster MOPAB347 [3.256 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB347  
About • paper received ※ 18 May 2021       paper accepted ※ 08 June 2021       issue date ※ 23 August 2021  
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MOPAB350 RF Buncher Cavity for Polarized He-3 Beam at BNL simulation, alignment, insertion, booster 1090
 
  • T. Kanesue, S.M. Trabocchi
    BNL, Upton, New York, USA
  • A. Murata
    TIT, Tokyo, Japan
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
A 100.625 MHz quar­ter wave res­onator type rf buncher cav­ity was fab­ri­cated for po­lar­ized He-3 spin ro­ta­tor beam line at BNL. This cav­ity will be in­stalled in the ex­ist­ing EBIS-To-Booster beam line to pro­vide ef­fec­tive volt­age of more than 40 kV for 2 MeV/u 3He2+ beam. This cav­ity has a large drift tube inner di­am­e­ter of 80 mm and small gap length of 5 mm. The buncher con­sists of 3 sec­tions, which are a cav­ity main body in­clud­ing drift tube, stem, and inner wall, a lid with a power cou­pler, and a lid with an in­duc­tive tuner. The main body was ma­chined from a bulk cop­per only by CNC ma­chin­ing. The re­sult of low power test agreed well with rf sim­u­la­tion with­out any align­ment. The dif­fer­ence be­tween mea­sured and cal­cu­lated res­o­nant fre­quency was <0.1 %, and mea­sured Q value was 92 % of that in sim­u­la­tion. The cav­ity rf de­sign and test re­sults will be shown. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB350  
About • paper received ※ 26 May 2021       paper accepted ※ 28 May 2021       issue date ※ 25 August 2021  
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MOPAB353 Design of a compact Ka-Band Mode Launcher for High-gradient Accelerators coupling, simulation, quadrupole, accelerating-gradient 1100
 
  • G. Torrisi, G.S. Mauro, G. Sorbello
    INFN/LNS, Catania, Italy
  • M. Behtouei, L. Faillace, B. Spataro, A. Variola
    INFN/LNF, Frascati, Italy
  • V.A. Dolgashev
    SLAC, Menlo Park, California, USA
  • L. Faillace, M. Migliorati
    Sapienza University of Rome, Rome, Italy
  • M. Migliorati
    INFN-Roma1, Rome, Italy
  • J.B. Rosenzweig
    UCLA, Los Angeles, California, USA
  • G. Sorbello
    University of Catania, Catania, Italy
  
  In this work, we pre­sent the RF de­sign of a table-top Ka-Band mode launcher op­er­at­ing at 35.98 GHz. The struc­ture con­sists of a sym­met­ri­cal 4-port WR28 rec­tan­gu­lar-TE10-to-cir­cu­lar-TM01 mode con­verter that is used to cou­ple a peak out­put RF power of 5 MW (pulse length up to 50 ns and rep­e­ti­tion rate up to 100 Hz) in Ka-Band lin­ear ac­cel­er­a­tor able to achieve very high ac­cel­er­at­ing gra­di­ents (up to 200 MV/m). Nu­mer­i­cal sim­u­la­tions have been car­ried out with the 3D full-wave com­mer­cial sim­u­la­tor Ansys HFSS in order to ob­tain a pre­lim­i­nary tun­ing of the ac­cel­er­at­ing field flat­ness at the op­er­at­ing fre­quency f0=35.98 GHz. The main RF pa­ra­me­ters, such as re­flec­tion co­ef­fi­cient, trans­mis­sion losses, and con­ver­sion ef­fi­ciency are given to­gether with a ver­i­fi­ca­tion of the field az­imuthal sym­me­try which avoids di­pole and quadru­pole de­flect­ing modes. To sim­plify fu­ture man­u­fac­tur­ing, re­duce fab­ri­ca­tion costs, and also re­duce the prob­a­bil­ity of RF break­down, the pro­posed new geom­e­try has "open" con­fig­u­ra­tion. This geom­e­try elim­i­nates the flow of RF cur­rents through crit­i­cal joints and al­lows this de­vice to be milled from metal blocks.  
poster icon Poster MOPAB353 [3.131 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB353  
About • paper received ※ 19 May 2021       paper accepted ※ 09 June 2021       issue date ※ 11 August 2021  
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MOPAB355 Multi-Objective Optimization of RF Structures impedance, controls, RF-structure, ECR 1103
 
  • S.J. Smith, R. Apsimon, G. Burt, M.J.W. Southerby
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • S. Setiniyaz
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • S. Setiniyaz
    Lancaster University, Lancaster, United Kingdom
  
  In this work, we apply multi-ob­jec­tive op­ti­miza­tion meth­ods to sin­gle-cell cav­ity mod­els gen­er­ated using non-uni­form ra­tio­nal basis splines (NURBS). This mod­el­ing method uses con­trol points and a NURBS to gen­er­ate the cav­ity geom­e­try, which al­lows for greater flex­i­bil­ity in the shape, lead­ing to im­proved per­for­mance. Using this ap­proach and multi-ob­jec­tive ge­netic al­go­rithms (MOGAs) we find the Pareto fron­tiers for the typ­i­cal key quan­ti­ties of in­ter­est (QoI) in­clud­ing peak fields, shunt im­ped­ance and the mod­i­fied Poynt­ing vec­tor. Vi­su­al­iz­ing these re­sults be­comes in­creas­ingly more dif­fi­cult as the num­ber of ob­jec­tives in­creases, there­fore, in order to un­der­stand these fron­tiers, we pro­vide sev­eral tech­niques for an­a­lyz­ing, vi­su­al­iz­ing and using multi-di­men­sional Pareto fronts specif­i­cally for RF cav­ity de­sign.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB355  
About • paper received ※ 19 May 2021       paper accepted ※ 15 July 2021       issue date ※ 01 September 2021  
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MOPAB356 The ESS MEBT RF Buncher Cavities Conditioning Process vacuum, controls, MEBT, EPICS 1107
 
  • I. Bustinduy, N. Garmendia, P.J. González, A. Kaftoosian, S. Masa, I. Mazkiaran, L.C. Medina, J.L. Muñoz
    ESS Bilbao, Zamudio, Spain
  • J. Etxeberria, J.P.S. Martins
    ESS, Lund, Sweden
  
  Funding: This work is part of FEDER-TRACKS project, co-funded by the European Regional Development Fund (ERDF) .
As part of the 5 MW Eu­ro­pean Spal­la­tion Source (ESS), the Medium En­ergy Beam Trans­port (MEBT) was de­signed, as­sem­bled, and in­stalled in the tun­nel since May 2020 by ESS-Bil­bao. This sec­tion of the ac­cel­er­a­tor is lo­cated be­tween the Radio Fre­quency Quadru­pole (RFQ) and the Drift Tube Linac (DTL). The main pur­pose of the MEBT is to match the in­com­ing beam from the RFQ both trans­versely and lon­gi­tu­di­nally into the DTL. The lon­gi­tu­di­nal match­ing is achieved by three 352.209 MHz RF buncher cav­i­ties. In this paper, we focus on the RF con­di­tion­ing process for each set of power cou­pler and buncher cav­ity. For this pur­pose, dif­fer­ent tools were de­vel­oped on EPICS and Python as well as elec­tron­ics hard­ware such as Fast In­ter­lock Mod­ule (FIM) and tim­ing sys­tem. These tools served to au­tom­a­tize both the cav­ity fre­quency tun­ing and the power ramp-up process and will be de­scribed in de­tail in the fol­low­ing sec­tions. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB356  
About • paper received ※ 18 May 2021       paper accepted ※ 09 June 2021       issue date ※ 17 August 2021  
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MOPAB357 The New Design of the RF System for the SPS-II Light Source storage-ring, booster, impedance, linac 1110
 
  • N. Juntong, T. Chanwattana, S. Chunjarean, S. Krainara, T. Phimsen, T. Pulampong
    SLRI, Nakhon Ratchasima, Thailand
  • K. Manasatitpong
    Synchrotron Light Research Institute (SLRI), Muang District, Thailand
  
  The new light source fa­cil­ity in Thai­land, SPS-II, is a ring-based 3 GeV light source with a cir­cum­fer­ence of ap­prox­i­mately 330 m. The tar­get stored beam cur­rent is 300 mA with an emit­tance of below 1.0 nm rad. The in­jec­tor has been changed from a full en­ergy linac to a booster in­jec­tor with 150 MeV linac. The main RF fre­quency has been re­con­sid­ered to a low-fre­quency range at 119 MHz. Low fre­quency is cho­sen with the ben­e­fit of low RF volt­age for a high RF ac­cep­tance to­gether with ex­pe­ri­ence with the pre­sent ring RF sys­tem of 118 MHz. De­tails of RF fre­quency con­sid­er­a­tion will be dis­cussed. The re­quire­ments and de­tails of the RF sys­tems in the booster ring and the stor­age ring will be pre­sented.  
poster icon Poster MOPAB357 [1.696 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB357  
About • paper received ※ 17 May 2021       paper accepted ※ 08 June 2021       issue date ※ 10 August 2021  
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MOPAB358 Design and Measurement of the 1.4 GHz Cavity for LEReC Linac electron, resonance, GUI, HOM 1113
 
  • B.P. Xiao, J.C. Brutus, J.M. Fite, K. Hamdi, D. Holmes, K. Mernick, K.S. Smith, J.E. Tuozzolo, T. Xin, A. Zaltsman
    BNL, Upton, New York, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
The Low En­ergy RHIC elec­tron Cooler (LEReC) is the first elec­tron cooler based on rf ac­cel­er­a­tion of elec­tron bunches. To fur­ther im­prove RHIC lu­mi­nos­ity for heavy ion beam en­er­gies below 10 GeV/nu­cleon, a nor­mal con­duct­ing RF cav­ity at 1.4 GHz was de­signed and fab­ri­cated for the LINAC that will pro­vide longer elec­tron bunches for the LEReC. It is a sin­gle-cell cav­ity with an ef­fec­tive cav­ity length shorter than half of the 1.4 GHz wave­length. This cav­ity was fab­ri­cated and tested on-site at BNL to ver­ify RF prop­er­ties, i.e. the res­o­nance fre­quency, FPC cou­pling strength, tuner sys­tem per­for­mance, and high power tests. In this paper, we re­port the RF test re­sults for this cav­ity. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB358  
About • paper received ※ 17 May 2021       paper accepted ※ 25 June 2021       issue date ※ 10 August 2021  
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MOPAB359 Operational Experience and Redesign of the Tuner without Spring Fingers for the LEReC Warm Cavity operation, vacuum, SRF, electron 1116
 
  • B.P. Xiao, J.M. Brennan, J.C. Brutus, K. Mernick, S. Polizzo, S.K. Seberg, F. Severino, K.S. Smith, A. Zaltsman
    BNL, Upton, New York, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
A folded coax­ial tuner with­out spring fin­gers was de­signed for the Low En­ergy RHIC elec­tron Cooler (LEReC) 2.1 GHz warm cav­ity. Dur­ing RHIC run 2019, this tuner was found to cause cav­ity trips via dif­fer­ent fail­ure modes. After an­a­lyz­ing these fail­ure modes, a new straight coax­ial tuner with­out spring fin­gers was pro­posed and was in­stalled. We show the op­er­a­tional ex­pe­ri­ence of the new tuner in this paper. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB359  
About • paper received ※ 17 May 2021       paper accepted ※ 25 June 2021       issue date ※ 12 August 2021  
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MOPAB361 Threshold in Filling Failure of RF Cavity Caused by Beam Loading in Multipactor multipactoring, simulation, electron, experiment 1122
 
  • J. Pang
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
  • Y. Dong
    Institute of Applied Physics and Computational Mathematics, People’s Republic of China
  • Y. Du
    Institute of Fluid Physics,, China Academy of Engineering Physics, Mianyang, People’s Republic of China
  
  Funding: NSFC
A pulsed RF cav­ity would be heav­ily de­tuned caused by beam load­ing of mul­ti­pactor cur­rent in the RF fill­ing process. Mul­ti­pactor zone would be ex­pended by sev­eral times than that in sta­tic states with as­sump­tions of fixed volt­age and no beam load­ing. The dy­namic of mul­ti­pactor in the RF fill­ing process was sim­u­lated by cou­pling with pa­ra­me­ters of ex­ter­nal cir­cuit with the de­vel­oped sim­u­la­tion code, and test in ex­per­i­ments with a par­al­lel-plate res­onator. Thresh­old of RF volt­age, which means the lower bound­ary of peak volt­age of mul­ti­pactor zone, had been quan­ti­fied with dif­fer­ent cav­ity pa­ra­me­ters. When we in­creased the gap length, the mea­sured thresh­old be­came larger due to the ion­iza­tion in back­ground gas. Then the sec­ondary emis­sion fac­tor would be in­creased in sim­u­la­tion for con­sis­tence with the ex­per­i­ment re­sults. Ad­di­tion­ally, some mul­ti­pactor phe­nom­e­non could not be pre­dicted pre­cisely be­cause the sim­u­la­tion code did not take ac­count of ion­iza­tion. The hys­tere­sis of phase and en­ergy of ion­iza­tion elec­trons would be a new dri­ving fac­tor for the growth of mul­ti­pactor in cer­tain con­di­tions. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB361  
About • paper received ※ 19 May 2021       paper accepted ※ 24 May 2021       issue date ※ 15 August 2021  
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MOPAB363 Design, Characteristics and Dynamic Properties of Mobile Plunger-based Frequency Tuning System for Coaxial Half Wave Resonators operation, experiment, controls, resonance 1129
 
  • D. Bychanok, S. Huseu, S.A. Maksimenko, A.E. Sukhotski
    INP BSU, Minsk, Belarus
  • A.V. Butenko, E. Syresin
    JINR, Dubna, Moscow Region, Russia
  • M. Gusarova, M.V. Lalayan, S.M. Polozov
    MEPhI, Moscow, Russia
  • V.S. Petrakovsky, A.I. Pokrovsky, A. Shvedov, S.V. Yurevich
    Physical-Technical Institute of the National Academy of Sciences of Belarus, Minsk, Belarus
  • Y. Tamashevich
    HZB, Berlin, Germany
  
  The prac­ti­cal re­al­iza­tion of a pro­to­type of the fre­quency tun­ing sys­tem (FTS) for coax­ial half-wave cav­i­ties (HWR) for the Nu­clotron-based Ion Col­lider fA­cil­ity (NICA) in­jec­tor is pre­sented. The im­pact of FTS on elec­tro­mag­netic pa­ra­me­ters of cop­per HWR pro­to­type is ex­per­i­men­tally stud­ied and dis­cussed. The most im­por­tant pa­ra­me­ters like tun­ing range, tun­ing sen­si­tiv­ity, the de­pen­dence of the res­o­nant fre­quency on the po­si­tion of the plungers are es­ti­mated. The ef­fec­tive op­er­a­tion al­go­rithms of the pro­posed FTS are dis­cussed and an­a­lyzed. The dy­namic char­ac­ter­is­tics of FTS are in­ves­ti­gated and showed the abil­ity to ad­just the fre­quency with an ac­cu­racy of about 70 Hz.  
poster icon Poster MOPAB363 [3.597 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB363  
About • paper received ※ 18 May 2021       paper accepted ※ 09 June 2021       issue date ※ 28 August 2021  
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MOPAB365 Construction and First Test Results of the Barrier and Harmonic RF Systems for the NICA Collider collider, vacuum, injection, electron 1136
 
  • A.G. Tribendis, Y.A. Biryuchevsky, K.N. Chernov, A.N. Dranitchnikov, E. Kenzhebulatov, A.A. Kondakov, A.A. Krasnov, Ya.G. Kruchkov, S.A. Krutikhin, G.Y. Kurkin, A.M. Malyshev, A.Yu. Martynovsky, N.V. Mityanina, S.V. Motygin, A.A. Murasev, V.N. Osipov, V.M. Petrov, E. Pyata, E. Rotov, V.V. Tarnetsky, I.A. Zapryagaev, A.A. Zhukov
    BINP SB RAS, Novosibirsk, Russia
  • O.I. Brovko, A.M. Malyshev, I.N. Meshkov, E. Syresin
    JINR, Dubna, Moscow Region, Russia
  • I.N. Meshkov
    Saint Petersburg State University, Saint Petersburg, Russia
  • E. Rotov
    NSU, Novosibirsk, Russia
  • A.G. Tribendis
    NSTU, Novosibirsk, Russia
  • A.V. Zinkevich
    Triada-TV, Novosibirsk, Russia
  
  This paper re­ports on the de­sign fea­tures and con­struc­tion progress of the three RF sys­tems for the NICA col­lider being built at JINR, Dubna. Each of the two col­lider rings has three RF sys­tems named RF1 to 3. RF1 is a bar­rier bucket sys­tem used for par­ti­cles cap­tur­ing and ac­cu­mu­la­tion dur­ing in­jec­tion, RF2 and 3 are res­o­nant sys­tems op­er­at­ing at 22nd and 66th har­mon­ics of the rev­o­lu­tion fre­quency and used for the 22 bunches for­ma­tion. The RF sys­tems are de­signed and pro­duced by Bud­ker INP. Solid state RF power am­pli­fiers de­vel­oped by the Tri­ada-TV com­pany, Novosi­birsk, are used for dri­ving the RF2 and three cav­i­ties. Two RF1 sta­tions were al­ready de­liv­ered to JINR, the pro­to­types of the RF2 and 3 sta­tions were built and suc­cess­fully tested at BINP. Se­ries pro­duc­tion of all eight RF2 and six­teen RF3 sta­tions is in progress. The de­sign mod­i­fi­ca­tions and test re­sults are pre­sented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB365  
About • paper received ※ 18 May 2021       paper accepted ※ 24 May 2021       issue date ※ 19 August 2021  
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MOPAB366 Improving Magnetic Materials for RCS Cavity Tuners solenoid, simulation, booster, synchrotron 1139
 
  • R.L. Madrak, N.M. Curfman, G.V. Romanov, C.-Y. Tan, I. Terechkine
    Fermilab, Batavia, Illinois, USA
  • G. Das, A.K. Samanta
    Ceramic Magnetics, Inc., National Magnetics Group, Inc., Bethlehem, USA
  
  Funding: United States Department of Energy, Contract No. DE-AC02-07CH11359
Within the Lab Di­rected R&D Pro­gram at Fer­mi­lab, and in part­ner­ship with Na­tional Mag­net­ics, we have re­cently begun to study and at­tempt to im­prove the loss pa­ra­me­ter in gar­net ma­te­r­ial. This could be used for fast tuner ap­pli­ca­tions such as in rapid cy­cling syn­chro­trons. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB366  
About • paper received ※ 19 May 2021       paper accepted ※ 25 May 2021       issue date ※ 23 August 2021  
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MOPAB371 A Coupon Tester for Normal Conducting High-Gradient Materials coupling, vacuum, RF-structure, klystron 1147
 
  • J.W. Lewellen, D. Gorelov, D. Perez, E.I. Simakov
    LANL, Los Alamos, New Mexico, USA
  • M.E. Schneider
    Michigan State University, East Lansing, Michigan, USA
  
  Funding: Los Alamos National Laboratory LDRD Program
A coupon tester is an RF struc­ture used to sub­ject a ma­te­r­ial sam­ple to very high RF fields, with the fields on the sam­ple, or coupon, being higher than else­where in the cav­ity. To date, most such cav­i­ties were orig­i­nally in­tended to ex­plore the RF prop­er­ties of su­per­con­duct­ing ma­te­ri­als, and can ex­pose the sam­ple to strong mag­netic fields, but weak to no elec­tric fields. As part of a pro­gram to de­velop ma­te­ri­als and struc­tures for high-gra­di­ent (> 100 MV/m), low-break­down-rate nor­mal-con­duct­ing ac­cel­er­a­tors, we have de­signed a C-band (5.712 GHz) cav­ity in­tended to sub­ject sam­ples to both mag­netic and elec­tric fields com­pa­ra­ble to those ex­pe­ri­enced in high-gra­di­ent struc­ture de­signs, using a TM-mode cav­ity; the elec­tric and mag­netic fields along the sam­ple coupon can be di­rectly com­pared to the fields on the iris of high-gra­di­ent struc­tures. This poster will pre­sent the de­sign cri­te­ria for our coupon tester cav­ity, nom­i­nal op­er­at­ing pa­ra­me­ters, and our struc­ture con­cept. The cav­ity de­sign will be re­fined over the next sev­eral months, and will be con­structed and in ser­vice near the start of 2022. 		 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB371  
About • paper received ※ 17 May 2021       paper accepted ※ 26 May 2021       issue date ※ 25 August 2021  
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MOPAB374 Creating Exact Multipolar Fields in Accelerating RF Cavities via an Azimuthally Modulated Design simulation, quadrupole, dipole, collider 1154
 
  • L.M. Wroe, S.L. Sheehy
    JAI, Oxford, United Kingdom
  • R. Apsimon
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • M. Dosanjh
    CERN, Meyrin, Switzerland
  • S.L. Sheehy
    The University of Melbourne, Melbourne, Victoria, Australia
  
  In this paper, we pre­sent a novel method for de­sign­ing RF struc­tures with specif­i­cally tai­lored mul­ti­po­lar field con­tri­bu­tions. This has a range of ap­pli­ca­tions, in­clud­ing the sup­pres­sion of un­wanted mul­ti­po­lar fields or the in­tro­duc­tion of wanted terms, such as for quadru­pole fo­cus­ing. In this ar­ti­cle, we out­line the gen­eral de­sign method­ol­ogy and com­pare the ex­pected re­sults to 3D CST sim­u­la­tions.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB374  
About • paper received ※ 19 May 2021       paper accepted ※ 08 June 2021       issue date ※ 10 August 2021  
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MOPAB376 Design and Fabrication of a Quadrupole Resonator for SRF R&D SRF, quadrupole, niobium, radio-frequency 1158
 
  • R. Monroy-Villa, W. Hillert, M. Wenskat
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  • S. Gorgi Zadeh, P. Putek
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
  • R. Monroy-Villa, D. Reschke, J.H. Thie
    DESY, Hamburg, Germany
  
  As Nb su­per­con­duct­ing ra­dio-fre­quency (SRF) cav­i­ties are now ap­proach­ing the the­o­ret­i­cal lim­its of the ma­te­r­ial, a va­ri­ety of dif­fer­ent sur­face treat­ments have been de­vel­oped to fur­ther im­prove their per­for­mance; al­though no fully un­der­stood the­ory is yet avail­able. Small su­per­con­duct­ing sam­ples are stud­ied to char­ac­ter­ize their ma­te­r­ial prop­er­ties and their evo­lu­tion under dif­fer­ent sur­face treat­ments. To study the RF prop­er­ties of such sam­ples under re­al­is­tic SRF con­di­tions at low tem­per­a­tures, a test cav­ity called quadru­pole res­onator (QPR) is cur­rently being fab­ri­cated. In this work we re­port the sta­tus of the QPR at Uni­ver­sität Ham­burg in col­lab­o­ra­tion with DESY. Our de­vice is based on the QPRs op­er­ated at CERN and at HZB and its de­sign will allow for test­ing sam­ples under cav­ity-like con­di­tions, i.e., at tem­per­a­tures be­tween 2K and 8 K, under mag­netic fields up to 120mT and with op­er­at­ing fre­quen­cies of 433 MHz, 866 MHz and 1300 MHz. Fab­ri­ca­tion tol­er­ance stud­ies on the elec­tro­mag­netic field dis­tri­b­u­tions and sim­u­la­tions of the sta­tic de­tun­ing of the de­vice, to­gether with a sta­tus re­port on the cur­rent man­u­fac­tur­ing process, will be pre­sented.  
poster icon Poster MOPAB376 [1.119 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB376  
About • paper received ※ 26 May 2021       paper accepted ※ 09 June 2021       issue date ※ 23 August 2021  
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MOPAB379 Topological Optimization on SRF Cavities for Nuclear and High Energy Physics niobium, superconducting-cavity, radiation, simulation 1162
 
  • H. Gassot
    Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
  
  Topol­ogy op­ti­miza­tion has been de­vel­oped for more than twenty years. The progress of ad­di­tive man­u­fac­tur­ing boosts the de­vel­op­ment in topo­log­i­cal op­ti­miza­tion since the de­sign can be com­pletely in­no­vated and re­al­ized by 3D print­ing. The po­ten­tial for cost re­duc­tions thanks to weight min­i­miza­tion give an in­ter­est­ing per­spec­tive for the small pro­duc­tion of nio­bium su­per­con­duct­ing ra­dio-fre­quency cav­i­ties, com­monly used in ac­cel­er­a­tors. The tra­di­tional man­u­fac­tur­ing tech­nolo­gies of cav­i­ties are based on multi-stage processes while ad­di­tive man­u­fac­tur­ing tech­nolo­gies can built fully func­tional parts in a sin­gle op­er­a­tion. For mod­ern ac­cel­er­a­tors that use su­per­con­duct­ing linac, in­clud­ing en­ergy re­cov­ery linacs (ERLs), it is par­tic­u­larly im­por­tant to know the per­spec­tives of ad­di­tive man­u­fac­tur­ing for SRF cav­i­ties. In this paper, we try to build a pre­lim­i­nary per­cep­tion of topo­log­i­cal op­ti­miza­tion in su­per­con­duct­ing cav­i­ties man­u­fac­tur­ing in­no­va­tion.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB379  
About • paper received ※ 11 May 2021       paper accepted ※ 17 August 2021       issue date ※ 17 August 2021  
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MOPAB380 Status and Progress of the RF System for High Energy Photon Source photon, storage-ring, booster, low-level-rf 1165
 
  • P. Zhang, J. Dai, Z.W. Deng, L. Guo, T.M. Huang, D.B. Li, J. Li, Z.Q. Li, H.Y. Lin, Y.L. Luo, Q. Ma, F. Meng, Z.H. Mi, Q.Y. Wang, X.Y. Zhang, F.C. Zhao, H.J. Zheng
    IHEP, Beijing, People’s Republic of China
  
  Funding: This work was supported in part by High Energy Photon Source, a major national science and technology infrastructure in China and in part by the Chinese Academy of Sciences.
High En­ergy Pho­ton Source (HEPS) is a 6 GeV dif­frac­tion-lim­ited syn­chro­tron light source cur­rently under con­struc­tion in Bei­jing. It adopts a dou­ble-fre­quency RF sys­tem with 166.6 MHz as fun­da­men­tal and 499.8 MHz as third har­monic. The fun­da­men­tal cav­ity is mak­ing use of a su­per­con­duct­ing quar­ter-wave β=1 struc­ture and the third har­monic is of su­per­con­duct­ing el­lip­ti­cal sin­gle-cell geom­e­try for the stor­age ring, while nor­mal-con­duct­ing 5-cell cav­i­ties are cho­sen for the booster ring. A total of 900 kW RF power shall be de­liv­ered to the beam by the 166.6 MHz cav­i­ties and the third har­monic cav­i­ties are ac­tive. All cav­i­ties are dri­ven by solid-state power am­pli­fiers and the RF fields are reg­u­lated by dig­i­tal low-level RF con­trol sys­tems. The cav­ity and an­cil­lar­ies, high-power RF sys­tem and low-level RF con­trol sys­tem are in the pro­to­typ­ing phase. This paper pre­sents the cur­rent sta­tus and progress of the RF sys­tem for HEPS. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB380  
About • paper received ※ 09 May 2021       paper accepted ※ 09 June 2021       issue date ※ 12 August 2021  
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MOPAB382 Synchrotron Light Shielding for the 166 MHz Superconducting RF Section at High Energy Photon Source shielding, synchrotron, storage-ring, radiation 1169
 
  • X.Y. Zhang, Z.Q. Li, Q. Ma, P. Zhang
    IHEP, Beijing, People’s Republic of China
  
  Funding: This work was supported by High Energy Photon Source, a major national science and technology infrastructure in China.
The High En­ergy Photo Source (HEPS) pro­ject has been under con­struc­tion since 2019, and will be first dif­frac­tion-lim­ited syn­chro­tron light source in China. A 6 GeV elec­tron beam with 200 mA cur­rent will be stored in the main ring. If syn­chro­tron light pro­duced from this en­er­getic elec­tron beam hits the su­per­con­duct­ing cav­ity’s sur­face, it would cause ther­mal break­down of the su­per­con­duc­tiv­ity. In the cur­rent lat­tice de­sign, these lights can­not be fully blocked by the col­li­ma­tor in the up­stream lat­tice cell, there­fore a shield­ing scheme in­side the rf sec­tion is re­quired. This how­ever brings great chal­lenges to the al­ready lim­ited space. The de­sign of the col­li­ma­tor has been fo­cused on ful­fill­ing shield­ing re­quire­ments while op­ti­miz­ing beam im­ped­ance, syn­chro­tron light power den­sity, ther­mal and me­chan­i­cal sta­bil­i­ties. Shield­ing ma­te­ri­als are sub­se­quently cho­sen with ded­i­cated cool­ing to en­sure long-term sta­ble op­er­a­tions. In this paper, a shield­ing scheme in­side the rf sec­tion of the HEPS stor­age ring is pre­sented. The syn­chro­tron light mainly from the up­stream bend­ing mag­net is suc­cess­fully block. The sen­si­tiv­ity to beam po­si­tion move­ment and in­stal­la­tion error is also an­a­lyzed. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB382  
About • paper received ※ 17 May 2021       paper accepted ※ 11 June 2021       issue date ※ 25 August 2021  
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MOPAB383 Pressure Test for Large Grain and Fine Grain Niobium Cavities niobium, SRF, experiment, FEM 1173
 
  • M. Yamanaka, T. Dohmae, H. Inoue, T. Saeki, K. Umemori, Y. Watanabe, K. Yoshida
    KEK, Ibaraki, Japan
  • K. Enami
    Tsukuba University, Ibaraki, Japan
  
  The pres­sure test was per­formed using a fine grain (FG) and a large grain (LG) nio­bium cav­i­ties. The cav­ity is 1.3 GHz 3-cell TESLA-like shape. The cav­ity was housed in a steel ves­sel. Water is sup­plied into the ves­sel and the cav­ity out­side is pres­sur­ized. The ap­ply­ing pres­sure and the nat­ural fre­quency of cav­ity were mea­sured dur­ing the pres­sure test. The FG and LG cav­i­ties were de­formed greatly and the pres­sure dropped sud­denly at 3.4 MPa and 1.6 MPa, re­spec­tively. The fre­quency shifted up to 3.4 MHz and 1.3 MHz, re­spec­tively. There was no leak after the pres­sure test, so the cav­ity did not rup­ture under above pres­sure. The re­sult of the pres­sure at LG cav­ity is less half than that of the FG cav­ity. We cal­cu­lated the stress dis­tri­b­u­tion in the struc­ture by ap­ply­ing outer water pres­sure using a FEM. The max­i­mum stress at cell when above test pres­sure is ap­plied, are 146 MPa in FG and 73 MPa in LG, re­spec­tively. These stresses are sim­i­lar to ten­sile strength of nio­bium spec­i­men mea­sure by our­selves. The re­sult of pres­sure tests agrees well with the cal­cu­la­tion.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB383  
About • paper received ※ 19 May 2021       paper accepted ※ 22 June 2021       issue date ※ 13 August 2021  
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MOPAB384 Nb3Sn Coating of Twin Axis Cavity for Accelerator Applications linac, niobium, SRF, dipole 1175
 
  • J.K. Tiskumara, S.U. De Silva, J.R. Delayen, H. Park
    ODU, Norfolk, Virginia, USA
  • J.R. Delayen, H. Park, U. Pudasaini, C.E. Reece
    JLab, Newport News, Virginia, USA
  • G.V. Eremeev
    Fermilab, Batavia, Illinois, USA
  
  Funding: Research supported by DOE Office of Science Accelerator Stewardship Program Award DE- SC0019399. Partially authored by Jefferson Science Associates under contract no. DEAC0506OR23177
A Su­per­con­duct­ing twin axis cav­ity con­sist­ing of two iden­ti­cal beam pipes that can ac­cel­er­ate and de­cel­er­ate beams within the same struc­ture has been pro­posed for the En­ergy Re­cov­ery Linac (ERL) ap­pli­ca­tions. There are two nio­bium twin axis cav­i­ties at JLab fab­ri­cated with the in­ten­tion of later Nb3Sn coat­ing and now we are pro­gress­ing to coat them using vapor dif­fu­sion method. Nb3Sn is a po­ten­tial al­ter­nate ma­te­r­ial for re­plac­ing Nb in SRF cav­i­ties for bet­ter per­for­mance and re­duc­ing op­er­a­tional costs. Be­cause of ad­vanced geom­e­try, larger sur­face area, in­creased num­ber of ports and hard to reach areas of the twin axis cav­i­ties, the usual coat­ing ap­proach de­vel­oped for typ­i­cal el­lip­ti­cal sin­gle-axis cav­i­ties must be eval­u­ated and re­quires to be ad­justed. In this con­tri­bu­tion, we re­port the first re­sults from the coat­ing of a twin axis cav­ity and dis­cuss cur­rent chal­lenges with an out­look for the fu­ture. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB384  
About • paper received ※ 19 May 2021       paper accepted ※ 24 May 2021       issue date ※ 20 August 2021  
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MOPAB385 An Overview of RF Systems for the EIC SRF, electron, HOM, luminosity 1179
 
  • R.A. Rimmer, J.P. Preble
    JLab, Newport News, Virginia, USA
  • K.S. Smith, A. Zaltsman
    BNL, Upton, New York, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under DOE Contract No. DE-SC0012704, by Jefferson Science Associates under contract DE-SC0002769, and by SLAC under Contract No. DE-AC02-76SF00515.
The Elec­tron Ion Col­lider (EIC) to be con­structed at Brookhaven Na­tional Lab­o­ra­tory in the USA will be a com­plex sys­tem of ac­cel­er­a­tors pro­vid­ing high lu­mi­nos­ity, high po­lar­iza­tion, vari­able cen­ter of mass en­ergy col­li­sions be­tween elec­trons and pro­tons or ions. To achieve this a va­ri­ety of RF sys­tems are re­quired. They must pro­vide for cap­ture, for­ma­tion and stor­age of Am­pere-class beams in the elec­tron and hadron stor­age rings (ESR and HSR), fast ac­cel­er­a­tion of high-charge po­lar­ized elec­tron bunches in the rapid cy­cling syn­chro­tron (RCS), pro­vi­sion of cold high cur­rent elec­tron bunches in the high-en­ergy cooler ERL and pre­cise high-gra­di­ent crab­bing of elec­trons and hadrons ei­ther side of the in­ter­ac­tion point. The chal­lenges in­clude strong HOM damp­ing in the stor­age ring cav­i­ties and cooler ERL, very high fun­da­men­tal mode power in the ESR and cooler in­jec­tor, ex­tremely sta­ble low-noise op­er­a­tion of the crab cav­i­ties, mit­i­ga­tion of tran­sient beam load­ing from gaps, and op­er­at­ing over a wide range of en­er­gies and beam cur­rents. We de­scribe the high-level sys­tem pa­ra­me­ters and prin­ci­pal de­sign choices made and progress on the R&D plan to de­velop these state of the art sys­tems. 		 
poster icon Poster MOPAB385 [1.268 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB385  
About • paper received ※ 18 May 2021       paper accepted ※ 31 May 2021       issue date ※ 22 August 2021  
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MOPAB386 Development of Nitrogen-Doping Technology for SHINE SRF, niobium, ECR, linac 1182
 
  • Y. Zong, X. Huang, Z. Wang
    SINAP, Shanghai, People’s Republic of China
  • J.F. Chen, H.T. Hou, D. Wang, J.N. Wu, Y.X. Zhang
    SARI-CAS, Pudong, Shanghai, People’s Republic of China
  • P.C. Dong
    Shanghai Advanced Research Institute, Pudong, Shanghai, People’s Republic of China
  • Y.W. Huang
    ShanghaiTech University, Shanghai, People’s Republic of China
  • J. Rong
    SSRF, Shanghai, People’s Republic of China
  
  The Shang­hai HIgh rep­e­ti­tion rate XFEL aNd Ex­treme light fa­cil­ity (SHINE) is under con­struc­tion, which needs six hun­dred 1.3GHz cav­i­ties with high qual­ity fac­tor. In this paper, we pre­sent the newest stud­ies on sin­gle cell cav­i­ties with ni­tro­gen dop­ing and cold EP treat­ment, show­ing an ob­vi­ous im­prove­ment com­pared with the pre­vi­ous re­sults.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB386  
About • paper received ※ 21 May 2021       paper accepted ※ 08 June 2021       issue date ※ 12 August 2021  
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MOPAB388 Status of the High Power Couplers for ESS Elliptical Cavities cryomodule, simulation, vacuum, SRF 1186
 
  • C. Arcambal, P. Bosland, G. Devanz, T. Hamelin, C. Madec, C. Marchand, M. Oublaid, G. Perreu, C. Servouin, C. Simon
    CEA-IRFU, Gif-sur-Yvette, France
  • M. Baudrier, C. Mayri, S. Regnaud, T.V. Vacher
    CEA-DRF-IRFU, France
  
  In the frame­work of the Eu­ro­pean Spal­la­tion Source (ESS), CEA Paris-Saclay is re­spon­si­ble for the de­liv­ery of 30 cry­omod­ules (9 medium beta (β = 0.67) and 21 high beta (β = 0.86) ones). Each cry­omod­ule con­tains 4 el­lip­ti­cal cav­i­ties equipped with a radio fre­quency power cou­pler. The ESS nom­i­nal pulse is 1.1 MW max­i­mum peak power over a width of 3.6 ms at a rep­e­ti­tion rate of 14 Hz. The de­sign of the cou­plers for medium beta and for high beta cav­i­ties is the same, ex­cept a small dif­fer­ence of the an­tenna pen­e­tra­tion to ad­just the Qext. The mass pro­duc­tion of the 120 cou­plers started and all the medium beta cou­plers have been con­di­tioned at room tem­per­a­ture. The first cry­omod­ules equipped with the power cou­plers were suc­cess­fully tested at high RF power and with cav­i­ties at 2K reach­ing the ESS nom­i­nal pulse. The main issue at the start of the se­ries pro­duc­tion could be fixed and it was due to bad TiN coat­ings that caused ab­nor­mal di­elec­tric losses in the win­dow. Thus, this paper deals with the TiN coat­ing de­fect, pre­sents the con­di­tion­ing pro­ce­dure and gives a con­di­tion­ing re­port of these 36 cou­plers.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB388  
About • paper received ※ 19 May 2021       paper accepted ※ 24 May 2021       issue date ※ 30 August 2021  
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MOPAB390 Development of a 166.6 MHz Low-Level RF System by Direct Sampling for High Energy Photon Source LLRF, controls, photon, pick-up 1189
 
  • D.B. Li, H.Y. Lin, Q.Y. Wang, P. Zhang
    IHEP, Beijing, People’s Republic of China
  
  Funding: This work was supported by High Energy Photon Source, a major national science and technology infrastructure in China.
A dig­i­tal low-level radio fre­quency (LLRF) sys­tem by di­rect sam­pling has been pro­posed for 166.6 MHz su­per­con­duct­ing cav­i­ties at High En­ergy Pho­ton Source (HEPS). The RF field in­side the cav­i­ties has to be con­trolled bet­ter than ±0.1% (peak to peak) in am­pli­tude and ±0.1 deg (peak to peak) in phase. Con­sid­er­ing that the RF fre­quency is 166.6 MHz, which is well within the ana­log band­width of mod­ern high-speed ADCs and DACs, di­rect RF sam­pling and di­rect dig­i­tal mod­u­la­tion can be achieved. A dig­i­tal LLRF sys­tem uti­liz­ing di­rect sam­pling has there­fore been de­vel­oped with em­bed­ded ex­per­i­men­tal physics and in­dus­trial con­trol sys­tem (EPICS) in the field pro­gram­ma­ble gate array (FPGA). The per­for­mance in the lab has been char­ac­ter­ized in a self-closed loop with a resid­ual peak-to-peak noise of ±0.05% in am­pli­tude and ±0.03 deg in phase, which is well below the HEPS spec­i­fi­ca­tions. Fur­ther tests on a warm 166.6 MHz cav­ity in the lab are also pre­sented. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB390  
About • paper received ※ 17 May 2021       paper accepted ※ 09 June 2021       issue date ※ 11 August 2021  
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MOPAB391 Conduction Cooling Methods for Nb3Sn SRF Cavities and Cryomodules SRF, controls, accelerating-gradient, simulation 1192
 
  • N.A. Stilin, A.T. Holic, M. Liepe, R.D. Porter, J. Sears, Z. Sun
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Rapid progress in the per­for­mance of Nb3Sn SRF cav­i­ties dur­ing the last few years has made Nb3Sn an en­ergy ef­fi­cient al­ter­na­tive to tra­di­tional Nb cav­i­ties, thereby ini­ti­at­ing a fun­da­men­tal shift in SRF tech­nol­ogy. These Nb3Sn cav­i­ties can op­er­ate at sig­nif­i­cantly higher tem­per­a­tures than Nb cav­i­ties while si­mul­ta­ne­ously re­quir­ing less cool­ing power. This crit­i­cal prop­erty en­ables the use of new, ro­bust, turn-key style cryo­genic cool­ing schemes based on con­duc­tion cool­ing with com­mer­cial cry­ocool­ers. Cor­nell Uni­ver­sity has de­vel­oped and tested a 2.6 GHz Nb3Sn cav­ity as­sem­bly which uti­lizes such cool­ing meth­ods. These tests have demon­strated sta­ble RF op­er­a­tion at 10 MV/m and the mea­sured ther­mal dy­nam­ics match what is found in nu­mer­i­cal sim­u­la­tions.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB391  
About • paper received ※ 20 May 2021       paper accepted ※ 10 June 2021       issue date ※ 17 August 2021  
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MOPAB392 Alternative RF Tuning Methods Performed on Spoke Cavities for ESS and MYRRHA Projects operation, target, simulation, experiment 1196
 
  • P. Duchesne, S. Blivet, G. Olivier, G. Olry, T. Pépin-Donat
    Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
  
  In order to ob­tain the tar­get fre­quency in op­er­a­tion, the res­o­nant fre­quency of su­per­con­duct­ing ra­diofre­quency cav­i­ties is con­trolled and ad­justed from the man­u­fac­tur­ing to the end of prepa­ra­tion phase. Reach­ing this right fre­quency can be chal­leng­ing due to the nar­row fre­quency range de­fined by the tun­ing sen­si­tiv­ity of the cav­ity and the ca­pa­bil­ity of the tuner. Me­chan­i­cal de­for­ma­tion until plas­tic­ity is at­tained is of great in­ter­est to tune SRF cav­i­ties when large fre­quency shift is needed. But once a cav­ity is dressed with its he­lium tank, the only ac­ces­si­ble part is its beam pipe, re­duc­ing the me­chan­i­cal ac­tion to a push/pull ac­tion. This lim­ited pos­si­bil­ity has hence to be skil­fully as­so­ci­ated with chem­i­cal etch­ing. An orig­i­nal me­chan­i­cal tun­ing of Spoke dressed cav­i­ties con­sists in in­creas­ing the pres­sure in­side the he­lium tank to in­duce a per­ma­nent de­for­ma­tion of the cav­ity walls. The fre­quency shift in­duced by non­lin­ear de­for­ma­tion is nu­mer­i­cally eval­u­ated in order to de­ter­mine the pres­sure in­cre­ments. Both meth­ods were suc­cess­fully per­formed on the cav­i­ties of the ESS ac­cel­er­a­tor and of the Myrrha pro­ject.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB392  
About • paper received ※ 20 May 2021       paper accepted ※ 25 June 2021       issue date ※ 02 September 2021  
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MOPAB393 Design of an RF-Dipole Crabbing Cavity System for the Electron-Ion Collider HOM, cryomodule, impedance, electron 1200
 
  • S.U. De Silva, J.R. Delayen
    ODU, Norfolk, Virginia, USA
  • J. Henry, F. Marhauser, H. Park, R.A. Rimmer
    JLab, Newport News, Virginia, USA
  
  The Elec­tron-Ion Col­lider re­quires sev­eral crab­bing sys­tems to fa­cil­i­tate head-on col­li­sions be­tween elec­tron and pro­ton beams in in­creas­ing the lu­mi­nos­ity at the in­ter­ac­tion point. One of the crit­i­cal rf sys­tems is the 197 MHz crab­bing sys­tem that will be used in crab­bing the pro­ton beam. Many fac­tors such as the low op­er­at­ing fre­quency, large trans­verse volt­age re­quire­ment, tight lon­gi­tu­di­nal and trans­verse im­ped­ance thresh­olds, and lim­ited beam line space makes the crab­bing cav­ity de­sign chal­leng­ing. The rf-di­pole cav­ity de­sign is con­sid­ered as one of the crab­bing cav­ity op­tions for the 197 MHz crab­bing sys­tem. The cav­ity is de­signed in­clud­ing the HOM cou­plers, FPC and other an­cil­lar­ies. This paper pre­sents the de­tailed elec­tro­mag­netic de­sign, me­chan­i­cal analy­sis, and con­cep­tual cry­omod­ule de­sign of the crab­bing sys­tem.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB393  
About • paper received ※ 26 May 2021       paper accepted ※ 02 June 2021       issue date ※ 11 August 2021  
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MOPAB394 Preliminary BCP Flow Field Investigation by CFD Simulations and PIV in a Transparent Model of a SRF Elliptical Low Beta Cavity experiment, simulation, SRF, laser 1204
 
  • A. D’Ambros, M. Bertucci, A. Bosotti, A.T. Grimaldi, P. Michelato, L. Monaco, R. Paparella, D. Sertore
    INFN/LASA, Segrate (MI), Italy
  • F. Cozzi, G. Pianello
    Politecnico di Milano, Milano, Italy
  • C. Pagani
    Università degli Studi di Milano & INFN, Segrate, Italy
  
  Stan­dard ver­ti­cal Buffered Chem­i­cal Pol­ish­ing (BCP) is one of the main sur­face treat­ment for Su­per­con­duct­ing Ra­diofre­quency (SRF) cav­i­ties. A fi­nite el­e­ment Com­pu­ta­tional Fluid Dy­namic (CFD) model has been de­vel­oped. Un­cer­tain­ties in the so­lu­tion of fluid sim­u­la­tions are not neg­li­gi­ble due to the com­plex geom­e­try of a SRF cav­ity; thus with­out an ex­per­i­men­tal val­i­da­tion, re­sults from this type of sim­u­la­tions can­not be con­fi­dently used to im­prove the process. To this aim, an ex­per­i­men­tal study was started to in­ves­ti­gate the fluid dy­nam­ics of the BCP process by means of Par­ti­cle Image Ve­locime­try (PIV) tech­nique. Simil­i­tude on Reynolds num­ber and Re­frac­tive Index Match­ing (RIM) tech­nique were also im­ple­mented to re­place the dan­ger­ous BCP mix­ture with a glyc­er­ine-wa­ter mix­ture. The paper de­scribes the pre­lim­i­nary re­sults from sim­u­la­tions and ex­per­i­ment.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB394  
About • paper received ※ 19 May 2021       paper accepted ※ 24 June 2021       issue date ※ 14 August 2021  
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MOPAB396 Measurements of Magnetic Field Penetration in Superconducting Materials for SRF Cavities SRF, experiment, solenoid, accelerating-gradient 1208
 
  • I.H. Senevirathne, J.R. Delayen, A.V. Gurevich
    ODU, Norfolk, Virginia, USA
  • J.R. Delayen, A-M. Valente-Feliciano
    JLab, Newport News, Virginia, USA
  
  Funding: This work is supported by NSF Grants PHY-1734075 and PHY-1416051, and DOE Award DE-SC0010081 and DE-SC0019399
Su­per­con­duct­ing ra­diofre­quency (SRF) cav­i­ties used in par­ti­cle ac­cel­er­a­tors op­er­ate in the Meiss­ner state. To achieve high ac­cel­er­at­ing gra­di­ents, the cav­ity ma­te­r­ial should stay in the Meiss­ner state under high RF mag­netic field with­out pen­e­tra­tion of vor­tices through the cav­ity wall. The field onset of flux pen­e­tra­tion into a su­per­con­duc­tor is an im­por­tant pa­ra­me­ter of merit of al­ter­na­tive su­per­con­duct­ing ma­te­ri­als other than Nb which can en­hance the per­for­mance of SRF cav­i­ties. There is a need for a sim­ple and ef­fi­cient tech­nique to mea­sure the onset of field pen­e­tra­tion into a su­per­con­duc­tor di­rectly. We have de­vel­oped a Hall probe ex­per­i­men­tal setup for the mea­sure­ment of the flux pen­e­tra­tion field through a su­per­con­duct­ing sam­ple placed under a small su­per­con­duct­ing so­le­noid mag­net which can gen­er­ate mag­netic fields up to 500 mT. The sys­tem has been cal­i­brated and used to mea­sure dif­fer­ent bulk and thin film su­per­con­duct­ing ma­te­ri­als. This sys­tem can also be used to study SIS mul­ti­layer coat­ings that have been pro­posed to en­hance the vor­tex pen­e­tra­tion field in Nb cav­i­ties. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB396  
About • paper received ※ 19 May 2021       paper accepted ※ 23 June 2021       issue date ※ 11 August 2021  
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MOPAB400 Development of Helium Vessel Welding Process for SNS PPU Cavities proton, cryomodule, neutron, accelerating-gradient 1212
 
  • P. Dhakal, E. Daly, G.K. Davis, J.F. Fischer, N.A. Huque, K. Macha, P.D. Owen, K.M. Wilson, M. Wiseman
    JLab, Newport News, Virginia, USA
  
  Funding: This manuscript has been authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
The Spal­la­tion Neu­tron Source Pro­ton Power Up­grade cav­i­ties are pro­duced by Re­search In­stru­ment with all the cav­ity pro­cess­ing done at ven­dor sites with final chem­istry ap­plied to the cav­ity to be elec­trop­o­l­ish­ing. Cav­i­ties are de­liv­ered to Jef­fer­son Lab, ready to be tested. One of the tasks to be com­pleted be­fore the ar­rival of pro­duc­tion-ready PPU cav­i­ties is to de­velop a ro­bust he­lium ves­sel weld­ing pro­to­col. We have suc­cess­fully de­vel­oped the process and ap­plied it to three six-cell high beta cav­i­ties. Here, we pre­sent the sum­mary of RF re­sults, weld­ing process de­vel­op­ment, and post he­lium ves­sel RF re­sults. 		 
poster icon Poster MOPAB400 [1.313 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB400  
About • paper received ※ 18 May 2021       paper accepted ※ 26 May 2021       issue date ※ 11 August 2021  
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MOPAB401 In-Situ EXAFS Investigations of Nb-Treatments in N2, O2 and N2-O2 Mixtures at Elevated Temperatures vacuum, site, experiment, niobium 1214
 
  • P. Rothweiler, B. Bornmann, J. Klaes, D. Lützenkirchen-Hecht, R. Wagner
    University of Wuppertal, Wuppertal, Germany
  
  Funding: We gratefully acknowledge financial support by the German Federal Ministry of Education and Research (BMBF) under project No. 05H18PXRB1.
Smooth poly­crys­talline Nb metal foils were treated in di­lute gas at­mos­pheres using a tem­per­a­ture of 900 °C. Trans­mis­sion mode X-ray ab­sorp­tion spec­troscopy (EX-AFS) at the Nb K-edge was used to in­ves­ti­gate changes in the atomic short-range order struc­ture of the bulk Nb-ma­te­r­ial in-situ. The ex­per­i­ments were per­formed in a ded­i­cated high-vac­uum cell that al­lows treat­ments in a di­lute gas at­mos­phere and tem­per­a­tures of up to 1200 °C. Typ­i­cal treat­ments in­clude (i) pre-heat­ing at 900 °C under high-vac­uum, (ii) gas ex­po­sure at the de­sired pres­sure and tem­per­a­ture, and (iii) cooldown to room tem­per­a­ture under vac­uum. EXAFS data were col­lected dur­ing the en­tire pro­ce­dure with a time res­o­lu­tion of 1 s. For the treat­ments in N2 at T = 900°C, the data show sub­tle changes in the Nb-EX­AFS, that are com­pat­i­ble with N-dop­ing of the bulk Nb, and the re­sults sug­gest Nb up­take on oc­ta­he­dral in­ter­sti­tial sites. How­ever, even a small O2-par­tial pres­sure leads to dis­tinct ox­i­da­tion of the Nb. The re­sults will be dis­cussed in more de­tail in the pre­sen­ta­tion. 		 
poster icon Poster MOPAB401 [2.032 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB401  
About • paper received ※ 19 May 2021       paper accepted ※ 26 May 2021       issue date ※ 28 August 2021  
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TUXA07 Beam Dynamics Study in a Dual Energy Storage Ring for Ion Beam Cooling* storage-ring, electron, focusing, emittance 1290
 
  • B. Dhital, G.A. Krafft
    ODU, Norfolk, Virginia, USA
  • Y.S. Derbenev, D. Douglas, A. Hutton, G.A. Krafft, F. Lin, V.S. Morozov, Y. Zhang
    JLab, Newport News, Virginia, USA
  
  Funding: * Work supported by the U.S. Department of Energy, Office of Science, and Office of Nuclear Physics under Contracts DE-AC05-06OR23177 and DE-AC02-06CH11357. / Jefferson Lab EIC Fellowship2020.
A dual en­ergy stor­age ring de­signed for beam cool­ing con­sists of two closed rings with sig­nif­i­cantly dif­fer­ent en­er­gies: the cool­ing and damp­ing rings. These two rings are con­nected by an en­ergy re­cov­er­ing su­per­con­duct­ing RF struc­ture that pro­vides the nec­es­sary en­ergy dif­fer­ence. In our de­sign, the RF ac­cel­er­a­tion has a main linac and har­monic cav­i­ties both run­ning at crest that at first ac­cel­er­ates the beam from low en­ergy EL to high en­ergy EH and then de­cel­er­ates the beam from EH to EL in the next pass. The pur­pose of the har­monic cav­i­ties is to ex­tend the bunch length in a dual en­ergy stor­age ring as such a longer bunch length may be very use­ful in a cool­ing ap­pli­ca­tion. Be­sides these cav­i­ties, a bunch­ing cav­ity run­ning on zero-cross­ing phase is used out­side of the com­mon beam­line to pro­vide the nec­es­sary lon­gi­tu­di­nal fo­cus­ing for the sys­tem. In this paper, we pre­sent a pre­lim­i­nary lat­tice de­sign along with the fun­da­men­tal beam dy­nam­ics study in such a dual en­ergy stor­age ring. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUXA07  
About • paper received ※ 19 May 2021       paper accepted ※ 07 June 2021       issue date ※ 25 August 2021  
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TUXB04 Fabrication and Tuning of a THz-Driven Electron Gun gun, electron, GUI, resonance 1297
 
  • S.M. Lewis, A.A. Haase, J.W. Merrick, E.A. Nanni, M.A.K. Othman, S.G. Tantawi
    SLAC, Menlo Park, California, USA
  • S.M. Lewis
    Fermilab, Batavia, Illinois, USA
  
  Funding: This work was supported by the Department of Energy Contract No. DE-AC02-76SF00515 (SLAC) and by NSF Grant No. PHY-1734015.
We have de­vel­oped a THz-dri­ven field emis­sion elec­tron gun and beam char­ac­ter­i­za­tion as­sem­bly. The two cell stand­ing-wave gun op­er­ates in the pi mode at 110.08 GHz. It is de­signed to pro­duce 360 keV elec­trons with 500 kW of input power sup­plied by a 110 GHz gy­ro­tron. Mul­ti­ple gun struc­tures were elec­tro­formed in cop­per using a high pre­ci­sion di­a­mond-turned man­drel. The field emis­sion cath­ode is a rounded cop­per tip lo­cated in the first cell. The cav­ity res­o­nances were me­chan­i­cally tuned using az­imuthal com­pres­sion. This work will dis­cuss de­tails of the fab­ri­ca­tion and tun­ing and pre­sent the re­sults of low power mea­sure­ments. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUXB04  
About • paper received ※ 18 May 2021       paper accepted ※ 22 June 2021       issue date ※ 28 August 2021  
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TUXC03 Ferro-Electric Fast Reactive Tuner Applications for SRF Cavities SRF, beam-loading, operation, controls 1305
 
  • N.C. Shipman, A. Castilla, M.R. Coly, F. Gerigk, A. Macpherson, N. Stapley, H. Timko
    CERN, Geneva, Switzerland
  • I. Ben-Zvi
    BNL, Upton, New York, USA
  • G. Burt, A. Castilla
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • C.-J. Jing, A. Kanareykin
    Euclid TechLabs, Solon, Ohio, USA
  
  A Ferro-Elec­tric fast Re­ac­tive Tuner (FE-FRT) is a novel type of RF cav­ity tuner con­tain­ing a low loss fer­ro­elec­tric ma­te­r­ial. FE-FRTs have no mov­ing parts and allow cav­ity fre­quen­cies to be changed ex­tremely quickly (on the timescale of 100s of ns or less). They are of par­tic­u­lar in­ter­est for SRF cav­i­ties as they can be placed out­side the liq­uid he­lium en­vi­ron­ment and with­out an FE-FRT it’s typ­i­cally very dif­fi­cult to tune SRF cav­i­ties quickly. FE-FRTs can be used for a wide va­ri­ety of use cases in­clud­ing mi­cro­phon­ics sup­pres­sion, RF switch­ing, and tran­sient beam load­ing com­pen­sa­tion. This promises en­tirely new op­er­a­tional ca­pa­bil­i­ties, in­creased per­for­mance and cost sav­ings for a va­ri­ety of ex­ist­ing and pro­posed ac­cel­er­a­tors. An overview of the the­ory and po­ten­tial ap­pli­ca­tions will be dis­cussed in de­tail.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUXC03  
About • paper received ※ 19 May 2021       paper accepted ※ 02 August 2021       issue date ※ 01 September 2021  
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TUPAB016 ESS RFQ: Installation and Tuning at Lund rfq, quadrupole, insertion, coupling 1372
 
  • P. Hamel, D. Chirpaz-Cerbat, M. Desmons, A.C. France, O. Piquet
    CEA-IRFU, Gif-sur-Yvette, France
  • A. Dubois, Y. Le Noa
    CEA-DRF-IRFU, France
  
  The 352 MHz Radio Fre­quency Quadru­pole (RFQ) for the Eu­ro­pean Spal­la­tion Source ERIC (ESS) has been de­liv­ered by the end of 2019. It has been pro­vided by CEA, IRFU, Saclay/France. It con­sists of five sec­tions with a total length of 4.6 m and ac­cel­er­ates the 70 mA pro­ton beam from 75 keV up to 3.6 MeV. It will be fed with 900 kW peak power through two coax­ial loop cou­plers. The in­stal­la­tion process (align­ment, vac­uum test), as well as the tun­ing process based on bead-pull mea­sure­ments, is pre­sented in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB016  
About • paper received ※ 18 May 2021       paper accepted ※ 06 July 2021       issue date ※ 30 August 2021  
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TUPAB017 Study of Conduction-Cooled Superconducting Quadrupole Magnets Combined with Dipole Correctors for the ILC Main Linac quadrupole, dipole, linac, SRF 1375
 
  • Y. Arimoto, S. Michizono, Y. Morikawa, N. Ohuchi, T. Oki, H. Shimizu, K. Umemori, X. Wang, A. Yamamoto, Y. Yamamoto, Z.G. Zong
    KEK, Ibaraki, Japan
  • V.S. Kashikhin
    Fermilab, Batavia, Illinois, USA
  
  A su­per­con­duct­ing rf (SRF) cry­omod­ule for In­ter­na­tional Lin­ear Col­lider(ILC) Main Linac equips focus/steer­ing mag­nets. The mag­nets are "su­per­fer­ric" mag­nets with four su­per­con­duct­ing (SC) race track coils con­duc­tively cooled from the cry­omod­ule LHe sup­ply pipe. The quadru­pole field gra­di­ent and di­pole field are 40 T/m and 0.1 T, re­spec­tively. The mag­net length and iron-pole ra­dius are 1 m and 0.045 m, re­spec­tively. It is known that dark cur­rent is gen­er­ated at SRF cav­i­ties and ac­cel­er­ated through the fol­low­ing linac string. The dark cur­rent reaches and heats the SC mag­nets. It is es­ti­mated that the power de­po­si­tion in the mag­net may reach more than a few watts and tem­per­a­ture of the SC coils may lo­cally reach to crit­i­cal tem­per­a­ture of NbTi. It is im­por­tant to make the mag­net not reach quench with suf­fi­cient con­duc­tion cool­ing. We aim to re­al­ize the SC mag­net which can sta­bly op­er­ate under such con­di­tion. We plan to de­velop test coils made of three types of SC ma­te­ri­als, NbTi, Nb3Sn, and MgB2 and study ther­mal char­ac­ter­is­tics and sta­bil­ity . We will de­velop a short model mag­net, based on the test coil re­sults. Here, we will pre­sent the mag­net de­sign study and the R&D plan.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB017  
About • paper received ※ 19 May 2021       paper accepted ※ 16 June 2021       issue date ※ 20 August 2021  
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TUPAB019 A High-Resolution, Low-Latency, Bunch-by-Bunch Feedback System for Nano-Beam Stabilization feedback, dipole, kicker, collider 1378
 
  • R.L. Ramjiawan, D.R. Bett, N. Blaskovic Kraljevic, T. Bromwich, P. Burrows, G.B. Christian, C. Perry
    JAI, Oxford, United Kingdom
  • D.R. Bett
    CERN, Geneva, Switzerland
  • N. Blaskovic Kraljevic
    ESS, Lund, Sweden
  • G.B. Christian
    DLS, Oxfordshire, United Kingdom
  
  A low-la­tency, bunch-by-bunch feed­back sys­tem em­ploy­ing high-res­o­lu­tion cav­ity Beam Po­si­tion Mon­i­tors (BPMs) has been de­vel­oped and tested at the Ac­cel­er­a­tor Test Fa­cil­ity (ATF2) at the High En­ergy Ac­cel­er­a­tor Re­search Or­ga­ni­za­tion (KEK), Japan. The feed­back sys­tem was de­signed to demon­strate nanome­ter-level ver­ti­cal sta­bi­liza­tion at the focal point of the ATF2 and can be op­er­ated using ei­ther a sin­gle BPM to pro­vide local beam sta­bi­liza­tion, or by using two BPMs to sta­bi­lize the beam at an in­ter­me­di­ate lo­ca­tion. The feed­back cor­rec­tion is im­ple­mented using a stripline kicker and the feed­back cal­cu­la­tions are per­formed on a dig­i­tal board con­structed around a Field Pro­gram­ma­ble Gate Array (FPGA). The feed­back per­for­mance was tested with trains of two bunches, sep­a­rated by 280ns, at a charge of ~1nC, where the ver­ti­cal off­set of the first bunch was mea­sured and used to cal­cu­late the cor­rec­tion to be ap­plied to the sec­ond bunch. The BPMs have been demon­strated to achieve an op­er­a­tional res­o­lu­tion of ~20nm. With the ap­pli­ca­tion of sin­gle-BPM and two-BPM feed­back, beam sta­bi­liza­tion of below 50nm and 41nm re­spec­tively has been achieved with a la­tency of 232ns.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB019  
About • paper received ※ 18 May 2021       paper accepted ※ 09 June 2021       issue date ※ 02 September 2021  
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TUPAB020 A Sub-Micron Resolution, Bunch-by-Bunch Beam Trajectory Feedback System and Its Application to Reducing Wakefield Effects in Single-Pass Beamlines feedback, wakefield, electron, kicker 1382
 
  • D.R. Bett, P. Burrows, C. Perry, R.L. Ramjiawan
    JAI, Oxford, United Kingdom
  • D.R. Bett
    CERN, Geneva, Switzerland
  • K. Kubo, T. Okugi, N. Terunuma
    KEK, Ibaraki, Japan
  
  A high-pre­ci­sion in­tra-bunch-train beam orbit feed­back cor­rec­tion sys­tem has been de­vel­oped and tested at the KEK Ac­cel­er­a­tor Test Fa­cil­ity, ATF2. The sys­tem uses the ver­ti­cal po­si­tion of the bunch mea­sured at two beam po­si­tion mon­i­tors to cal­cu­late a pair of kicks which are ap­plied to the next bunch using two up­stream kick­ers, thereby cor­rect­ing both the ver­ti­cal po­si­tion and tra­jec­tory angle. Using trains of two elec­tron bunches sep­a­rated in time by 187.6ns, the sys­tem was op­ti­mised so as to sta­bi­lize the beam off­set at the feed­back BPMs to bet­ter than 350nm, yield­ing a local tra­jec­tory angle cor­rec­tion to within 250n­rad. The qual­ity of the cor­rec­tion was ver­i­fied using three down­stream wit­ness BPMs and the re­sults were found to be in agree­ment with the pre­dic­tions of a lin­ear lat­tice model used to prop­a­gate the beam tra­jec­tory from the feed­back re­gion. This same model pre­dicts a cor­rected be am jit­ter of c.1nm at the focal point of the ac­cel­er­a­tor. Mea­sure­ments with a beam size mon­i­tor at this lo­ca­tion demon­strate that re­duc­ing the tra­jec­tory jit­ter of the beam by a fac­tor of 4 also re­duces the in­crease in the mea­sured beam size as a func­tion of beam charge by a fac­tor of ~1.6.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB020  
About • paper received ※ 13 May 2021       paper accepted ※ 01 July 2021       issue date ※ 22 August 2021  
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TUPAB035 ESS Medium Beta Cavities Status at INFN LASA SRF, linac, multipactoring, controls 1420
 
  • D. Sertore, M. Bertucci, M. Bonezzi, A. Bosotti, A. D’Ambros, A.T. Grimaldi, P. Michelato, L. Monaco, R. Paparella
    INFN/LASA, Segrate (MI), Italy
  • C. Pagani
    Università degli Studi di Milano & INFN, Segrate, Italy
  
  INFN Mi­lano con­tributes in-kind to the ESS ERIC Su­per­con­duct­ing Linac sup­ply­ing 36 cav­i­ties for the Medium Beta sec­tion of the pro­ton ac­cel­er­a­tor. The pro­duc­tion has reached com­ple­tion, being all the cav­i­ties me­chan­i­cal fab­ri­cated, BCP treated and, for most of them, also qual­i­fied with ver­ti­cal test at cold. In this paper, we re­port on the re­sults and lessons learnt and the ac­tions taken both for qual­ity con­trol man­ag­ing and re­cov­ery of the few cav­i­ties that did not reach the pro­ject goal after the first qual­i­fi­ca­tion test.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB035  
About • paper received ※ 19 May 2021       paper accepted ※ 14 June 2021       issue date ※ 15 August 2021  
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TUPAB037 The Design of a High Charge Polarized Preinjector for the Electron-Ion Collider cathode, gun, linac, electron 1428
 
  • E. Wang, W. Liu, V.H. Ranjbar, J. Skaritka, N. Tsoupas
    BNL, Upton, New York, USA
  • J.M. Grames, J. Guo
    JLab, Newport News, Virginia, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy
The de­sign of the elec­tron pre-in­jec­tor of the Elec­tron-Ion Col­lider (EIC) pro­ject to gen­er­ate 4 x 7 nC bunch has been ad­vanc­ing to meet the re­quire­ments for in­jec­tion into the Rapid Cy­cling Syn­chro­tron (RCS). The major chal­lenges are high charge trans­port and achiev­ing small en­ergy spread from 3 GHz trav­el­ing-wave plate(TWP). The de­signed prein­jec­tor in­cludes the po­lar­ized elec­tron source, bunch­ing sec­tion, TWP Linac, zigzag phase space ma­nip­u­la­tion and spin ro­ta­tor. In this re­port, we will dis­cuss the RF fre­quency se­lec­tion and the way to re­duce en­ergy spread down to 0.2% by lon­gi­tu­di­nal phase space ma­nip­u­late. We will also re­port the re­sults of beam­line sim­u­la­tion using space charge code and the con­cep­tual de­sign of spin ro­ta­tor. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB037  
About • paper received ※ 16 May 2021       paper accepted ※ 15 June 2021       issue date ※ 31 August 2021  
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TUPAB038 Simulation of the Filling Pattern Dependent Regenerative Beam Breakup Instabilities in Energy Recover Linacs HOM, linac, simulation, electron 1431
 
  • S. Setiniyaz, P.H. Williams
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • R. Apsimon
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • P.H. Williams
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  
  The in­ter­ac­tion of a trans­versely dis­placed beam with the higher modes (HOM) of the ac­cel­er­at­ing cav­i­ties causes build­ing up HOM volt­ages in the cav­ity, which in turn kicks the beam and in­creases the off­set fur­ther. This is known as re­gen­er­a­tive beam breakup (BBU) in­sta­bil­ity and it sets the beam thresh­old cur­rent for the sta­ble beam op­er­a­tion. A study by Se­tiniyaz et al.~[Se­tiniyaz2020] showed the fill­ing pat­tern and re­com­bi­na­tion schemes of multi-turn en­ergy re­cov­ery linacs (ERLs) can cre­ate many dif­fer­ent beam load­ing tran­sients, which can have a big im­pact on the cav­ity fun­da­men­tal mode volt­age and RF sta­bi­lizes. In this work, we ex­tend the study of the fill­ing pat­tern and re­com­bi­na­tion schemes to the BBU in­sta­bil­i­ties and thresh­old cur­rent. In the ERLs, the ac­cel­er­ated and de­cel­er­ated bunches can be or­dered dif­fer­ently while they pass through the cav­ity and form dif­fer­ent fill­ing pat­terns. Each pat­tern has a unique bunch en­ergy se­quence and bunch ar­rival times and hence in­ter­acts with cav­ity uniquely and thus dri­ves BBU dif­fer­ently. In this paper, we in­tro­duce a sim­u­la­tion tool to in­ves­ti­gate the fill­ing pat­tern de­pen­dence of the ERL BBU in­sta­bil­ity.
* S. Setiniyaz, R. Apsimon, and P. H. Williams, Phys. Rev. Accel. Beams 23, 072002, 2020.
 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB038  
About • paper received ※ 20 May 2021       paper accepted ※ 09 June 2021       issue date ※ 13 August 2021  
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TUPAB041 Detector Solenoid Compensation for the Electron-Ion Collider solenoid, coupling, electron, detector 1439
 
  • B.R. Gamage, T.J. Michalski, V.S. Morozov, R. Rajput-Ghoshal, A. Seryi, W. Wittmer, Y. Zhang
    JLab, Newport News, Virginia, USA
  • E. Gianfelice-Wendt
    Fermilab, Batavia, Illinois, USA
  • A. Kiselev, H. Lovelace III, B. Parker, S. Peggs, S. Tepikian, F.J. Willeke, H. Witte, Q. Wu
    BNL, Upton, New York, USA
  
  Funding: Jefferson Science Associates, LLC Contract No. DE-AC05-06OR23177, Fermi Research Alliance, LLC Contract No. DE-AC02-07CH11359, and Brookhaven Science Associates, LLC Contract No. DE-SC0012704
The cen­tral de­tec­tor in the pre­sent EIC de­sign in­cludes a 4 m long so­le­noid with an in­te­grated strength of up to 12 Tm. The elec­tron beam passes on-axis through the so­le­noid, but the hadron beam has an angle of 25 mrad. Thus the so­le­noid cou­ples hor­i­zon­tal and ver­ti­cal be­ta­tron mo­tion in both elec­tron and hadron stor­age rings, and causes a ver­ti­cal closed orbit ex­cur­sion in the hadron ring. The so­le­noid also cou­ples the trans­verse and lon­gi­tu­di­nal mo­tions of both beams, when crab cav­i­ties are also con­sid­ered. In this paper, we pre­sent schemes for closed orbit cor­rec­tion and cou­pling com­pen­sa­tion at the IP, in­clud­ing crab­bing. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB041  
About • paper received ※ 28 May 2021       paper accepted ※ 22 August 2021       issue date ※ 31 August 2021  
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TUPAB045 The Low Energy Injector Design for the Southern Advanced Photon Source electron, linac, gun, bunching 1450
 
  • Y. Han
    IHEP CSNS, Guangdong Province, People’s Republic of China
  • Y. Jiao, B. Li, X. Liu, S. Wang
    IHEP, Beijing, People’s Republic of China
  
  The South­ern Ad­vanced Pho­ton Source (SAPS) is a pro­ject under de­sign, which aims at con­struct­ing a 4th gen­er­a­tion stor­age ring with emit­tance below 100 pm.​rad at the elec­tron beam en­ergy of around 3.5 GeV. At pre­sent, two in­jec­tor op­tions are under con­sid­er­a­tion. One is a full en­ergy booster plus a low en­ergy in­jec­tor, and an­other is a full en­ergy linac in­jec­tor. In this paper, a pre­lim­i­nary de­sign of the low en­ergy in­jec­tor is pre­sented, which con­sists of an DC thermionic elec­tron gun, a bunch­ing sec­tion and an ac­cel­er­at­ing sec­tion. The beam en­ergy at the end of the in­jec­tor is about 150 MeV.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB045  
About • paper received ※ 17 May 2021       paper accepted ※ 09 June 2021       issue date ※ 21 August 2021  
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TUPAB053 Design Progress of ALS-U 3rd-Harmonic Cavity HOM, damping, impedance, simulation 1481
 
  • T.H. Luo, K.M. Baptiste, S. De Santis, D. Li, J.W. Staples, M. Venturini
    LBNL, Berkeley, California, USA
  • H.Q. Feng
    TUB, Beijing, People’s Republic of China
  
  Funding: Director, Office of Science, Office of Basic Energy Sciences, and LDRD Program of Lawrence Berkeley National Laboratory, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231
A higher-har­monic rf cav­ity (HHC) sys­tem is re­quired in the ALS-U stor­age ring to lengthen the bunches, re­duce in­tra­beam-scat­ter­ing ef­fects, and im­prove Tou­schek beam life­time. A 3rd har­monic, nor­mal con­duct­ing, pas­sive-cav­ity sys­tem has been cho­sen based on beam-dy­nam­ics re­quire­ments and cost con­sid­er­a­tions. We have ex­plored two op­tions for ALS-U 3HC sys­tem: a high-R/Q re-en­trant cav­ity with wave­guide HOM dampers, and a low-R/Q sys­tem with two el­lip­ti­cal cav­i­ties and HOM beam line ab­sorbers. In this paper, we pre­sent the re­cent progress on the cav­ity de­sign and re­lated beam dy­nam­ics stud­ies. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB053  
About • paper received ※ 19 May 2021       paper accepted ※ 11 June 2021       issue date ※ 18 August 2021  
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TUPAB072 The Status of a Grating Monochromator for Soft X-Ray Self-Seeding Experiment at SHINE electron, laser, FEL, free-electron-laser 1532
 
  • K.Q. Zhang
    SSRF, Shanghai, People’s Republic of China
  • H.X. Deng, C. Feng, B. Liu, T. Liu
    SARI-CAS, Pudong, Shanghai, People’s Republic of China
  
  The re­search sta­tus of a grat­ing mono­chro­ma­tor for soft X-ray self-seed­ing ex­per­i­ment at SHINE has been pre­sented in this paper. The mono­chro­ma­tor sys­tem in­cludes the vac­uum cav­ity, op­ti­cal el­e­ments, and me­chan­i­cal move­ment de­vices. Until now, the vac­uum cav­ity has fin­ished the man­u­fac­tured process com­pletely, the op­ti­cal mir­rors have fin­ished ma­chin­ing and mea­sured by the lon­gi­tu­di­nal trace pro­filer (LTP) and atomic force mi­cro­scope (AFM). To make sure the mono­chro­ma­tor sys­tem can achieve an op­ti­cal res­o­lu­tion of 1/10000 at the pho­ton en­ergy of 700-1300eV, the sys­tem has been in­te­grated and tested re­cently. In this year, the pre­vi­ous on­line ex­per­i­ment will be per­formed in the shang­hai soft X-ray free-elec­tron laser (FEL) user fa­cil­ity.  
poster icon Poster TUPAB072 [0.717 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB072  
About • paper received ※ 11 May 2021       paper accepted ※ 09 June 2021       issue date ※ 01 September 2021  
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TUPAB074 S-Band Transverse Deflecting Structure Design for CompactLight klystron, FEL, operation, impedance 1540
 
  • X.W. Wu, W. Wuensch
    CERN, Meyrin, Switzerland
  • S. Di Mitri
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  • N. Thompson
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  
  The Com­pact­Light pro­ject is cur­rently de­vel­op­ing the de­sign of a next gen­er­a­tion hard X-ray FEL fa­cil­ity, which is based on high-gra­di­ent X-band (12 GHz) struc­tures. How­ever, to carry out pump-and-probe ex­per­i­ments in the pro­ject, two-bunch op­er­a­tion with a spac­ing of 10 X-band rf cy­cles is pro­posed. A sub-har­monic trans­verse de­flect­ing struc­ture work­ing at S-band is pro­posed to di­rect the two bunches into two sep­a­rate FEL lines. The two FEL pulses will have in­de­pen­dently tun­able wave­lengths and can be com­bined in a sin­gle ex­per­i­ment with a tem­po­ral delay be­tween pulses of ± 100 fs. The rf de­sign of the trans­verse de­flec­tor is pre­sented in this paper.  
poster icon Poster TUPAB074 [1.557 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB074  
About • paper received ※ 19 May 2021       paper accepted ※ 10 June 2021       issue date ※ 11 August 2021  
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TUPAB077 Novel Open Cavity for Rotating Mode SLED-Type RF Pulse Compressors coupling, klystron, GUI, linear-collider 1547
 
  • X.W. Wu, A. Grudiev
    CERN, Meyrin, Switzerland
  
  A new X-band high-power ro­tat­ing mode SLAC En­ergy Dou­bler (SLED)-type rf pulse com­pres­sor is pro­posed. It is based on a novel cav­ity type, a sin­gle open bowl-shape en­ergy stor­age cav­ity with high Q0 and com­pact size, which is cou­pled to the wave­guide using a com­pact ro­tat­ing mode launcher. The novel cav­ity type is ap­plied to the rf pulse com­pres­sion sys­tem of the main linac rf mod­ule of the kly­stron-based op­tion of the Com­pact Lin­ear Col­lider (CLIC). Quasi-spher­i­cal ro­tat­ing modes of \rm{TE}1,2,4 and \rm{TE}1,2,13 are pro­posed for the cor­rec­tion cav­ity and stor­age cav­ity of the rf pulse com­pres­sion sys­tem re­spec­tively. The stor­age cav­ity work­ing at \rm{TE}1,2,13 has a Q0 of 240000 and a di­am­e­ter less than 33 cm. The de­sign of the pulse com­pres­sor and in par­tic­u­lar of the high-Q cav­ity will be pre­sented in de­tail.  
poster icon Poster TUPAB077 [1.229 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB077  
About • paper received ※ 19 May 2021       paper accepted ※ 10 June 2021       issue date ※ 12 August 2021  
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TUPAB098 Recent Progress Toward a Conduction-Cooled Superconducting Radiofrequency Electron Gun simulation, SRF, electron, accelerating-gradient 1604
 
  • O. Mohsen, N. Adams, V. Korampally, A. McKeown, D. Mihalcea, P. Piot, I. Salehinia, N. Tom
    Northern Illinois University, DeKalb, Illinois, USA
  • R. Dhuley, M.G. Geelhoed, D. Mihalcea, J.C.T. Thangaraj
    Fermilab, Batavia, Illinois, USA
  • P. Piot
    ANL, Lemont, Illinois, USA
  
  Funding: This work was supported by the US Department of Energy (DOE) under contract DE-SC0018367
High-rep­e­ti­tion-rate elec­tron sources have wide­spread ap­pli­ca­tions. This con­tri­bu­tion dis­cusses the progress to­ward a proof-of-prin­ci­ple demon­stra­tion for a con­duc­tion-cooled elec­tron source. The source con­sists of a sim­ple mod­i­fi­ca­tion of an el­lip­ti­cal cav­ity that en­hances the field elec­tric field at the pho­to­cath­ode sur­face. The source was cooled to cryo­genic tem­per­a­tures and pre­lim­i­nary mea­sure­ments for the qual­ity fac­tor and ac­cel­er­at­ing field were per­formed. Ad­di­tion­ally, we pre­sent fu­ture plans to im­prove the source along with sim­u­lated beam-dy­nam­ics per­for­mances. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB098  
About • paper received ※ 29 May 2021       paper accepted ※ 17 June 2021       issue date ※ 14 August 2021  
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TUPAB105 Simulation Studies for Dark Current Signature From DLS RF Gun simulation, electron, solenoid, cathode 1630
 
  • J. Karmakar, M. Aggarwal, S. Ghosh, B. Karmakar, P. Patra, B.K. Sahu, A. Sharma
    IUAC, New Delhi, India
  
  The Delhi Light source (DLS) is an up­com­ing com­pact THz fa­cil­ity at IUAC, New Delhi, based on pre-bunched FEL. RF con­di­tion­ing of the 2.6 cell S-band RF gun is presently car­ried out with a Cu photo-cath­ode (PC) plug and dark cur­rent is pro­duced when sub­stan­tial ac­cel­er­at­ing field is reached in­side the cav­ity. To iden­tify the pos­si­ble field emis­sion sites con­tribut­ing to dark cur­rent, sin­gle elec­tron ASTRA sim­u­la­tions are done with a phase scan of the RF field. The sim­u­la­tion is ex­tended to in­clude multi-par­ti­cle emis­sion from the PC edge as a ring. The en­er­gies pre­sent in the dark cur­rent is analysed from the the Fowler Nord­heim cur­rent plot and en­ergy phase scan plot. The dis­tri­b­u­tion of few dark cur­rent en­er­gies and their re­spec­tive tra­jec­to­ries upto the YAG screen at a given so­le­noid set­ting is traced and shown in the sim­u­la­tions. We also pre­sent the dark cur­rent im­ages cap­tured dur­ing the ini­tial RF con­di­tion­ing and try to com­pare it with the sim­u­la­tions.  
poster icon Poster TUPAB105 [0.742 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB105  
About • paper received ※ 19 May 2021       paper accepted ※ 17 August 2021       issue date ※ 28 August 2021  
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TUPAB109 Characterization of the X-Ray Angular Pointing Jitter in the LCLS Hard X-ray Undulator Line undulator, FEL, electron, detector 1640
 
  • R.A. Margraf, Z. Huang, J.P. MacArthur, G. Marcus, T. Sato, D. Zhu
    SLAC, Menlo Park, California, USA
  • Z. Huang
    Stanford University, Stanford, California, USA
  
  Funding: This work was supported by the Department of Energy, Laboratory Directed Research and Development program at SLAC National Accelerator Laboratory, under contract DE-AC02-76SF00515.
The an­gu­lar point­ing jit­ter of X-ray pulses pro­duced by an X-ray Free-Elec­tron Laser (XFEL) de­pends on both in­trin­sic prop­er­ties of the SASE (Self-am­pli­fied spon­ta­neous emis­sion) process and jit­ters in beam­line vari­ables such as elec­tron orbit. This jit­ter is of in­ter­est to the Cav­ity-Based XFEL (CBXFEL)* pro­ject at SLAC, which will lase seven un­du­la­tors in­side an X-ray cav­ity of four di­a­mond Bragg mir­rors. The CBXFEL cav­ity has a nar­row an­gu­lar band­width, thus large an­gu­lar jit­ters cause X-rays to leak out of the cav­ity and de­grade cav­ity ef­fi­ciency. To un­der­stand con­trib­u­tors to an­gu­lar point­ing jit­ter, we stud­ied the point­ing jit­ter of the Linac Co­her­ent Light Source (LCLS) Hard X-ray Un­du­la­tor line (HXU). Mono­chro­matic and pink X-rays were char­ac­ter­ized at the X-ray Pump Probe (XPP) in­stru­ment. We found pulses with high mono­chro­m­a­tized pulse en­ergy and small elec­tron beam orbit in the un­du­la­tor have the low­est an­gu­lar point­ing jit­ter. We pre­sent here our mea­sure­ment re­sults, dis­cuss why these fac­tors cor­re­late with point­ing sta­bil­ity, and pro­pose a strat­egy for CBXFEL to re­duce an­gu­lar point­ing jit­ter and ac­count for an­gu­lar point­ing jit­ter in cav­ity ef­fi­ciency mea­sure­ments.
*Gabriel Marcus et al. "CBXFEL Physics Requirements Document for the Optical cavity Based X-Ray Free Electron Lasers Research and Development Project." SLAC-I-120-103-121-00. Apr 2020. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB109  
About • paper received ※ 19 May 2021       paper accepted ※ 14 June 2021       issue date ※ 18 August 2021  
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TUPAB110 Measurement and Correction of RF Kicks in the LCLS Accelerator to Improve Two-Bunch Operation electron, FEL, klystron, experiment 1644
 
  • R.A. Margraf, F.-J. Decker, Z. Huang, G. Marcus
    SLAC, Menlo Park, California, USA
  • Z. Huang
    Stanford University, Stanford, California, USA
  
  Funding: This work was supported by the Department of Energy, Laboratory Directed Research and Development program at SLAC National Accelerator Laboratory, under contract DE-AC02-76SF00515.
RF kicks, caused by a mis­align­ment of an elec­tron beam and ac­cel­er­a­tion struc­ture, pro­duce an elec­tron orbit in the ac­cel­er­a­tor which de­creases the final en­ergy of the ac­cel­er­ated elec­tron beam and is detri­men­tal to las­ing elec­tron bunches in an X-ray Free Elec­tron Laser (XFEL). RF kicks can de­pend on the RF wave­form of the ac­cel­er­at­ing struc­ture, so con­trol­ling this ef­fect is par­tic­u­larly im­por­tant when two or more elec­tron bunches are ac­cel­er­ated within an RF fill time. Multi­bunch modes have been suc­cess­fully de­vel­oped for the Linac Co­her­ent Light Source (LCLS) ac­cel­er­a­tor at SLAC,* and are being con­tin­u­ally im­proved to ac­com­mo­date new ex­per­i­ments. One such ex­per­i­ment, the Cav­ity-Based XFEL (CBXFEL)** pro­ject will re­quire two elec­tron bunches sep­a­rated by 218.5 ns which must be iden­ti­cal in en­ergy and orbit. To re­duce vari­a­tion in en­ergy and orbit be­tween the two bunches, we stud­ied the RF kicks pro­duced by each of 75 ac­cel­er­a­tor seg­ments in the LCLS linac at sev­eral RF tim­ings. Here, we dis­cuss these mea­sure­ments and pro­pose a method to cor­rect RF kicks in the LCLS ac­cel­er­a­tor using cor­rec­tor dipoles and quadrupoles.
* F.-J. Decker, et al. Recent Developments and Plans for Two Bunch Operation, Proc. of FEL2017, TUP023.
** Gabriel Marcus et al. CBXFEL Physics Requirements Document. SLAC-I-120-103-121-00. 2020. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB110  
About • paper received ※ 19 May 2021       paper accepted ※ 15 June 2021       issue date ※ 25 August 2021  
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TUPAB127 Spare Gun Multi-Physics Analysis for LCLS-II gun, cathode, simulation, electron 1688
 
  • L. Xiao, C. Adolphsen, A. Cedillo, E.N. Jongewaard, X. Liu, C.-K. Ng, F. Zhou
    SLAC, Menlo Park, California, USA
  
  LBNL APEX VHF nor­mal con­duct­ing gun was adopted for LCLS-II CW op­er­a­tion to pro­vide ul­tra-bright high rep­e­ti­tion rate X-ray pulses. The ini­tial LCLS-II gun and in­jec­tor com­mis­sion­ing showed ex­ces­sive dark cur­rent dom­i­nated by field emis­sion around the cath­ode plug outer di­am­e­ter and the gun cav­ity nose. There is a con­cern that the dark cur­rent may get worse with time of op­er­a­tion. It is plan­ning to build a spare rf gun largely based on the cur­rent LCLS-II gun to re­place cur­rent LCLS-II gun. The pro­posed spare gun has a re­duced the peak elec­tri­cal fields around the cath­ode plug cor­ner and cav­ity nose by 10% through fur­ther op­ti­miz­ing APEX gun cav­ity shape. In ad­di­tion, there are some mod­er­ate mod­i­fi­ca­tions on the en­gi­neer­ing de­sign to in­crease me­chan­i­cal ro­bust­ness and vac­uum per­for­mance. SLAC de­vel­oped par­al­lel fi­nite-el­e­ment elec­tro­mag­netic code suite ACE3P is used to apply for the spare gun mod­el­ing in­clud­ing RF, ther­mal and struc­tural analy­sis at sta­tic and tran­sient states to en­sure its suc­cess­ful op­er­a­tion in LCLS-II. In this paper, the spare gun multi-physics analy­sis is de­scribed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB127  
About • paper received ※ 19 May 2021       paper accepted ※ 20 August 2021       issue date ※ 25 August 2021  
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TUPAB133 Brazing free RF Pulse Compressor for High Gradient Accelerators GUI, coupling, simulation, vacuum 1700
 
  • L. Kankadze, D. Alesini, F. Cardelli, G. Di Raddo, M. Diomede
    INFN/LNF, Frascati, Italy
  
  EURPRAXIA@​SPARC\LAB, is a pro­posal to up­grade the SPARC\LAB test fa­cil­ity (at LNF, Fras­cati) to a soft X-ray user fa­cil­ity based on plasma ac­cel­er­a­tion and high-gra­di­ent X-band (11.9942 GHz) ac­cel­er­at­ing mod­ules. Each mod­ule is made up of a group of 4 TW sec­tions as­sem­bled on a sin­gle girder and fed by one kly­stron by means of one rf pulse com­pres­sor sys­tem and a low at­ten­u­a­tion cir­cu­lar wave­guide net­work that trans­ports the rf power to the input hy­brids of the sec­tions. The pulse com­pres­sor is based on a sin­gle Bar­rel Open Cav­ity (BOC). The BOC use a ’whis­per­ing gallery’ mode which has an in­trin­si­cally high qual­ity fac­tor and op­er­ates in a res­o­nant ro­tat­ing wave regime. Com­pared to the con­ven­tional SLED scheme it re­quires a sin­gle cav­ity in­stead of two cav­i­ties and a 3-dB hy­brid. A new braze­less me­chan­i­cal de­sign has been pro­posed and is de­scribed in the pre­sent paper to­gether with the elec­tro-mag­netic and thermo-me­chan­i­cal sim­u­la­tions.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB133  
About • paper received ※ 21 May 2021       paper accepted ※ 15 June 2021       issue date ※ 27 August 2021  
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TUPAB166 A New Design of a Dressed Balloon Cavity with Superior Mechanical Properties multipactoring, SRF, linac, software 1769
 
  • R.A. Kostin, C. Jing, S. Ross
    Euclid Beamlabs, Bolingbrook, USA
  • I.V. Gonin, T.N. Khabiboulline, G.V. Romanov, V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
  • M.P. Kelly
    ANL, Lemont, Illinois, USA
  • R.E. Laxdal
    TRIUMF, Vancouver, Canada
  
  Funding: Work supported by the SBIR program of the U.S. Department of Energy, under grant DE-SC0020781
Su­per­con­duct­ing spoke cav­i­ties are prone to mul­ti­pactor - res­o­nant raise of a num­ber of elec­trons due to sec­ondary emis­sion. Re­cently pro­posed and tested by TRI­UMF bal­loon-type spoke cav­ity showed an out­stand­ing mul­ti­pactor (MP) sup­pres­sion prop­erty but un­for­tu­nately se­ri­ous Q degra­da­tion at high fields. A new fully de­vel­oped de­sign of a dressed bal­loon cav­ity which can be used for any pro­ton linac SSR2 sec­tion is de­vel­oped. The de­sign in­cor­po­rates ad­di­tional EP ports for high Q-fac­tor demon­stra­tion. Su­pe­rior prop­er­ties are demon­strated, such as ef­fec­tive mul­ti­pactor sup­pres­sion, 40% lower Lorentz force co­ef­fi­cient, zero sen­si­tiv­ity to ex­ter­nal pres­sure. This paper pre­sents the re­sults of cou­pled struc­tural Mul­ti­physics analy­sis, and en­gi­neer­ing de­sign of the dressed bal­loon cav­ity with EP ports. 		 
poster icon Poster TUPAB166 [1.394 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB166  
About • paper received ※ 15 May 2021       paper accepted ※ 21 June 2021       issue date ※ 12 August 2021  
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TUPAB167 Status of Conduction Cooled SRF Photogun for UEM/UED gun, SRF, cryomodule, shielding 1773
 
  • R.A. Kostin, C. Jing
    Euclid Beamlabs, Bolingbrook, USA
  • P.V. Avrakhov, A. Liu, Y. Zhao
    Euclid TechLabs, Solon, Ohio, USA
  
  Funding: DOE #DE-SC0018621
Ben­e­fit­ing from the rapid progress on RF pho­to­gun tech­nolo­gies in the past two decades, the de­vel­op­ment of MeV range ul­tra­fast elec­tron dif­frac­tion/mi­croscopy (UED and UEM) has been iden­ti­fied as an en­abling in­stru­men­ta­tion. UEM or UED use low power elec­tron beams with mod­est en­er­gies of a few MeV to study ul­tra­fast phe­nom­ena in a va­ri­ety of novel and ex­otic ma­te­ri­als. SRF pho­to­guns be­come a promis­ing can­di­date to pro­duce highly sta­ble elec­trons for UEM/UED ap­pli­ca­tions be­cause of the ul­tra­high shot-to-shot sta­bil­ity com­pared to room tem­per­a­ture RF pho­to­guns. SRF tech­nol­ogy was pro­hib­i­tively ex­pen­sive for in­dus­trial use until two re­cent ad­vance­ments: Nb3Sn and con­duc­tion cool­ing. The use of Nb3Sn al­lows to op­er­ate SRF cav­i­ties at higher tem­per­a­tures (4K) with low power dis­si­pa­tion which is within the reach of com­mer­cially avail­able closed-cy­cle cry­ocool­ers. Eu­clid is de­vel­op­ing a con­tin­u­ous wave (CW), 1.5-cell, MeV-scale SRF con­duc­tion cooled pho­to­gun op­er­at­ing at 1.3 GHz. In this paper, the tech­ni­cal de­tails of the de­sign and first ex­per­i­men­tal data are pre­sented. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB167  
About • paper received ※ 29 May 2021       paper accepted ※ 21 June 2021       issue date ※ 31 August 2021  
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TUPAB168 Beam Commissioning of a 325 MHz Proton IH-DTL at XiPAF DTL, proton, emittance, linac 1777
 
  • P.F. Ma, X. Guan, R. Tang, M.W. Wang, X.W. Wang, Q.Z. Xing, W.B. Ye, S.X. Zheng
    TUB, Beijing, People’s Republic of China
  • W. Chen, W.L. Liu, W. Lv, M.T. Qiu, B.C. Wang, D. Wang, M.C. Wang, Z.M. Wang, Y.H. Yan, Y. Yang, M.T. Zhao
    NINT, Xi’an, People’s Republic of China
  
  The In­ter-Dig­i­tal H-mode Drift Tube Linac (IH-DTL) is widely used as the main com­po­nent of in­jec­tors for med­ical syn­chro­trons. This paper de­scribes the beam com­mis­sion­ing of a com­pact 325 MHz IH-DTL with mod­i­fied KONUS beam dy­nam­ics at Ts­inghua Uni­ver­sity (THU). This IH-DTL ac­cel­er­ates the pro­ton beam from 3 MeV to 7 MeV in 1m. The av­er­age en­ergy of the beam is 7.0 MeV with the en­ergy spread range of -0.6 MeV to 0.3 MeV. The out­put trans­verse nor­mal­ized RMS emit­tance of the beam is 0.58 (x)/0.58 (y) pi mm mrad with the input emit­tance of 0.43 (x)/0.37 (y) pi mm mrad. The beam test re­sults show good agree­ment with the beam dy­nam­ics de­sign.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB168  
About • paper received ※ 08 May 2021       paper accepted ※ 16 June 2021       issue date ※ 13 August 2021  
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TUPAB170 Decouple Transverse Coupled Beam in the DTL with Tilted PMQs emittance, coupling, DTL, rfq 1785
 
  • P.F. Ma, X. Guan, R. Tang, X.W. Wang, Q.Z. Xing, X.D. Yu, S.X. Zheng
    TUB, Beijing, People’s Republic of China
  • Y.H. Pu, J. Qiao, C.P. Wang, X.C. Xie, F. Yang
    Shanghai APACTRON Particle Equipment Company Limited, Shanghai, People’s Republic of China
  
  The cou­pling of the beam is widely stud­ied in the ac­cel­er­a­tor physics field. Pro­jected trans­verse emit­tances eas­ily grow up if the beam is trans­versely-cou­pled. If we de­cou­ple the trans­verse cou­pled beam, the trans­verse emit­tance can be small. The ma­trix ap­proach based on the sym­plec­tic trans­for­ma­tion the­ory for de­cou­pling the cou­pled beam is sum­ma­rized. For a pro­ton ac­cel­er­a­tor, the trans­verse cou­pled beam is in­tro­duced by an RFQ tilted by 45°. The beam is de­cou­pled with the first five tilted quadrupoles mounted in the DTL sec­tion. A study on the gra­di­ent choice of the quadrupoles and the space charge ef­fect is given in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB170  
About • paper received ※ 08 May 2021       paper accepted ※ 21 June 2021       issue date ※ 01 September 2021  
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TUPAB173 ESS Drift Tube Linac Manufacturing, Assembly and Tuning DTL, linac, alignment, emittance 1797
 
  • F. Grespan, L. Antoniazzi, A. Baldo, C. Baltador, A. Battistello, L. Bellan, P. Bottin, M. Comunian, D. Conventi, E. Fagotti, L. Ferrari, A. Palmieri, R. Panizzolo, A. Pisent, D. Scarpa
    INFN/LNL, Legnaro (PD), Italy
  • R.A. Baron
    ESS, Lund, Sweden
  • T. Bencivenga, P. Mereu, C. Mingioni, M. Nenni, E. Nicoletti
    INFN-Torino, Torino, Italy
  • A.G. Colombo
    INFN- Sez. di Padova, Padova, Italy
  • B. Jones
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
  
  The Drift Tube Linac (DTL) for the ESS Linac will ac­cel­er­ate H+-beams of up to 62.5 mA peak cur­rent from 3.62 to 90 MeV. The struc­ture con­sists of five cav­i­ties. The first cav­ity (DTL1) is a 7.6 m long tank con­tain­ing 60 drift tubes, 23 fixed tuners, 3 mov­able tuners and 24 post-cou­plers, op­er­at­ing at a fre­quency of 352.21 MHz and an av­er­age ac­cel­er­at­ing field of 3.0 MV/m. The cav­ity is now as­sem­bled at ESS, the re­sults of align­ment and tun­ing are here pre­sented. The DTL1 "as-built" as been an­a­lyzed from the beam dy­nam­ics point of view. The man­u­fac­tur­ing of DTL4 and DTL3 is com­pleted and they are now under as­sem­bly at ESS. DTL2 and DTL5 man­u­fac­tur­ing will be com­pleted within 2021. The paper de­scribes the pro­duc­tion and as­sem­bly stages, with a focus on the sta­tis­tics of qual­ity check in terms of metrol­ogy, align­ment, leak tests.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB173  
About • paper received ※ 19 May 2021       paper accepted ※ 27 May 2021       issue date ※ 15 August 2021  
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TUPAB198 ESS DTL Tuning Using Machine Learning Methods network, DTL, linac, proton 1872
 
  • J.S. Lundquist, N. Milas, E. Nilsson
    ESS, Lund, Sweden
  • S. Werin
    Lund University, Lund, Sweden
  
  The Eu­ro­pean Spal­la­tion Source, cur­rently under con­struc­tion in Lund, Swe­den, will be the world’s most pow­er­ful neu­tron source. It is dri­ven by a pro­ton linac with a cur­rent of 62.5 mA, 2.86 ms long pulses at 14 Hz. The final sec­tion of its nor­mal-con­duct­ing front-end con­sists of a 39 m long drift tube linac (DTL) di­vided into five tanks, de­signed to ac­cel­er­ate the pro­ton beam from 3.6 MeV to 90 MeV. The high beam cur­rent and power im­pose chal­lenges to the de­sign and tun­ing of the ma­chine and the RF am­pli­tude and phase have to be set within 1% and 1 de­gree of the de­sign val­ues. The usual method used to de­fine the RF set-point is sig­na­ture match­ing, which can be a time con­sum­ing and chal­leng­ing process, and new tech­niques to meet the grow­ing com­plex­ity of ac­cel­er­a­tor fa­cil­i­ties are highly de­sir­able. In this paper we study the usage of Ma­chine Learn­ing to de­ter­mine the RF op­ti­mum am­pli­tude and phase. The data from a sim­u­lated phase scan is fed into an ar­ti­fi­cial neural net­work in order to iden­tify the needed changes to achieve the best tun­ing. Our test for the ESS DTL1 shows promis­ing re­sults, and fur­ther de­vel­op­ment of the method will be out­lined.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB198  
About • paper received ※ 17 May 2021       paper accepted ※ 21 June 2021       issue date ※ 10 August 2021  
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TUPAB211 The Accelerator System of IFMIF-DONES Multi-MW Facility linac, rfq, SRF, cryomodule 1910
 
  • I. Podadera, A. Ibarra, D. Jimenez-Rey, J. Mollá, C. Oliver, D. Regidor, R. Varela, C. de la Morena
    CIEMAT, Madrid, Spain
  • F. Arbeiter, V. Hauer
    KIT, Eggenstein-Leopoldshafen, Germany
  • N. Bazin, J. Dumas, L. Seguí
    CEA-IRFU, Gif-sur-Yvette, France
  • L. Bellan, E. Fagotti, A. Palmieri, A. Pisent
    INFN/LNL, Legnaro (PD), Italy
  • N. Chauvin, S. Chel, J. Plouin
    CEA-DRF-IRFU, France
  • G. Duglue, H. Dzitko
    F4E, Germany
  • W.C. Grabowski, A. Wysocka-Rabin
    NCBJ, Świerk/Otwock, Poland
  • M. Jaksic, T. Tadic
    RBI, Zagreb, Croatia
  • W. Królas
    IFJ-PAN, Kraków, Poland
  • R. López, A. Muñoz, C. Prieto
    Empresarios Agrupados, Madrid, Spain
  • O. Nomen, M. Sanmartí, F.J. Saura Esteban, B.K. Singh, D. Sánchez-Herranz
    IREC, Sant Adria del Besos, Spain
  
  Funding: Work carried out within EUROfusion Consortium and DONES-PreP and received funding from the Euratom research and training programme 2014-2018 & 2019-2020 under grants agreement No. 633053 & 870186
The IFMIF-DONES (DEMO-Ori­ented Neu­tron Early Source) fa­cil­ity has passed the pre­lim­i­nary de­sign phase and the de­tailed de­sign phase is very much ad­vanced. Next step will be the prepa­ra­tion phase for the con­struc­tion of the fa­cil­ity. The DONES fa­cil­ity aims at de­vel­op­ing a data­base of fu­sion-like ra­di­a­tion ef­fects on ma­te­ri­als to be used in fu­ture fu­sion re­ac­tors up to dam­age lev­els ex­pected in the EU DEMO. It will be based on an in­tense neu­tron source cre­ated by an ac­cel­er­ated deuteron beam (125 mA CW, 40 MeV) im­ping­ing on a liq­uid lithium cur­tain. The DONES Ac­cel­er­a­tor Sys­tems (AS) will be re­spon­si­ble of de­liv­er­ing this 5 MW D+ beam with very high avail­abil­ity. The beam ac­cel­er­a­tion will be per­formed by sev­eral stages: an ion source and LEBT, an RFQ, a MEBT, an SRF Linac and a HEBT trans­port­ing and de­liv­er­ing an op­ti­mized pro­file down to the tar­get. A high power RF sys­tem and sev­eral an­cil­lar­ies will en­sure the equip­ment is prop­erly op­er­ated. This con­tri­bu­tion will re­port the pre­sent sta­tus of the AS de­sign, the main chal­lenges faced, the R&D pro­gramme to over­come them, and the prospects for the con­struc­tion and com­mis­sion­ing of the DONES ac­cel­er­a­tor in Granada (Spain). 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB211  
About • paper received ※ 19 May 2021       paper accepted ※ 17 June 2021       issue date ※ 13 August 2021  
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TUPAB220 Longitudinal Dynamics with Harmonic Cavities under the Over-stretching Conditions detector, beam-loading, longitudinal-dynamics, bunching 1939
 
  • J.Y. Xu, H.S. Xu
    IHEP, Beijing, People’s Republic of China
  
  Higher har­monic cav­i­ties (HHCs) are often used to lengthen the bunches, mainly for in­creas­ing the Tou­schek life­time or for sup­press­ing the cou­pled-bunch in­sta­bil­i­ties in elec­tron stor­age rings. There have been quite many stud­ies on the beam dy­nam­ics with the con­sid­er­a­tion of HHCs. We re­vis­ited the basic lon­gi­tu­di­nal dy­nam­ics with HHCs. The de­riva­tion of the lon­gi­tu­di­nal equa­tions of mo­tion with HHCs will be pre­sented in this paper. The dif­fer­ence in the num­ber of fixed points at dif­fer­ent HHC set­tings (mainly under the over-stretch­ing con­di­tions) is also dis­cussed.  
poster icon Poster TUPAB220 [1.082 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB220  
About • paper received ※ 19 May 2021       paper accepted ※ 02 August 2021       issue date ※ 18 August 2021  
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TUPAB237 Symplectic Tracking Through Field Maps quadrupole, dipole, ion-source, radio-frequency 1992
 
  • S.D. Webb
    RadiaSoft LLC, Boulder, Colorado, USA
  • B.T. Folsom, E. Laface, R. Miyamoto
    ESS, Lund, Sweden
  
  For many ap­pli­ca­tions, it is nec­es­sary to track par­ti­cles using field maps, in­stead of an an­a­lytic rep­re­sen­ta­tion of the fields which is typ­i­cally not avail­able. These field maps come about while de­sign­ing el­e­ments such as re­al­is­tic mag­nets or ra­diofre­quency cav­i­ties, and rep­re­sent the field geom­e­try on a mesh in space. How­ever, sim­ple in­ter­po­la­tion of the fields from the field maps does not guar­an­tee that the re­sult­ing track­ing scheme sat­is­fies the sym­plec­tic con­di­tion. Here we pre­sent a gen­eral method to de­com­pose the field-map po­ten­tial in the sum of in­ter­po­lat­ing func­tions that pro­duces, by con­struc­tion, a sym­plec­tic in­te­gra­tor.  
poster icon Poster TUPAB237 [0.307 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB237  
About • paper received ※ 19 May 2021       paper accepted ※ 22 July 2021       issue date ※ 18 August 2021  
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TUPAB241 Characterization of the RF-Cavities geometry in Order to Optimize the Beam Parameters in S-Band On-Axis LINACs electron, target, emittance, impedance 2005
 
  • A. Khosravi, B. Shokri
    LAPRI, Tehran, Iran
  • N. Khosravi
    ILSF, Tehran, Iran
  
  The RF char­ac­ter­is­tics of an ac­cel­er­at­ing tube are pri­mar­ily as­signed to geo­met­ri­cal fea­tures of a cav­ity. As a con­se­quence of this geom­e­try, the final elec­tric field will make the shape of our Gauss­ian bunch and the final dose. The ac­cel­er­at­ing field can be stud­ied con­sid­er­ing the nose cone, gap, and bore ra­dius. In dual elec­tron linacs, the role of input power and bunch cur­rent is in­evitable. There­fore, the geo­met­ri­cal is­sues of RF-cav­i­ties are stud­ied in a 6MeV elec­tron on-axis SW tube. To make an ac­cu­rate com­par­i­son, each RF-cav­ity is de­signed and op­ti­mized by POIS­SON SU-PER­FISH. The op­ti­mized cav­i­ties are im­ported to the PIC solver of CST. Then the beam char­ac­ter­is­tics are stud­ied on a pre­de­fined tar­get.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB241  
About • paper received ※ 18 May 2021       paper accepted ※ 14 June 2021       issue date ※ 13 August 2021  
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TUPAB242 The Beam-Study of the Side and On-Axis RF Cavities in S-Band 6 MeV LINACs target, emittance, coupling, impedance 2008
 
  • A. Khosravi, B. Shokri
    LAPRI, Tehran, Iran
  • N. Khosravi
    ILSF, Tehran, Iran
  
  The geom­e­try of side and on-axis RF cav­i­ties are two mag­netic-cou­pled de­signs for the dif­fer­ent LINAC ap­pli­ca­tions. The elec­tro­mag­netic fields, RF power, beam pa­ra­me­ters, ther­mal sta­bil­ity, and man­u­fac­tur­ing costs are the most crit­i­cal fac­tors in cav­ity type se­lec­tion in each ap­pli­ca­tion. In this ar­ti­cle, both RF-cav­i­ties are op­ti­mized in POIS­SON SU­PER­FISH code to com­pare the beam pa­ra­me­ters ac­cu­rately. Then the op­ti­mized cav­i­ties are mak­ing a tube and com­pare in ASTRA 1D code and CST 3D soft­ware. At last, the ther­mal sen­si­tiv­ity of both mod­els is stud­ied in MPHYSICS mod­ule of the CST. As a re­sult, the final de­ci­sion can be achieved on the side or on-axis cav­i­ties con­sid­er­ing the input power, costs, beam prop­er­ties, and ther­mal sta­bil­ity for the dif­fer­ent ap­pli­ca­tions of the LINACs  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB242  
About • paper received ※ 18 May 2021       paper accepted ※ 21 June 2021       issue date ※ 26 August 2021  
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TUPAB243 Investigation of the Buncher Effect on Beam Properties in SW 3-6 MeV LINACs electron, emittance, target, impedance 2012
 
  • A. Khosravi, B. Shokri
    LAPRI, Tehran, Iran
  • N. Khosravi
    ILSF, Tehran, Iran
  
  The best qual­ity of an elec­tron beam is the pri­mary goal of a lin­ear ac­cel­er­a­tor de­sign. Beam-study on a buncher sec­tion can lead us to a bet­ter per­spec­tive of the mod­u­la­tion and ac­cel­er­a­tion of a beam to op­ti­mize the final Gauss­ian beam. Five se­tups of dif­fer­ent bunch­ers are de­signed, op­ti­mized, and pre­sented in this ar­ti­cle. A more bril­liant and con­verged beam with a higher cur­rent, trans­verse emit­tance and smaller beam size is the study’s goal.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB243  
About • paper received ※ 18 May 2021       paper accepted ※ 14 June 2021       issue date ※ 12 August 2021  
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TUPAB248 A Parallel Time Domain Thermal Solver for Transient Analysis of Accelerator Cavities gun, simulation, background, software 2030
 
  • C.-K. Ng, L. Ge, Z. Li, L. Xiao
    SLAC, Menlo Park, California, USA
  
  Funding: Work supported by US DOE under contract AC02-76SF00515.
Sim­u­la­tion of ther­mal ef­fects in ac­cel­er­a­tor cav­ity is nor­mally per­formed as­sum­ing steady state so­lu­tion where a sta­tic ther­mal solver suf­fices to eval­u­ate tem­per­a­ture gra­di­ents and im­pacts on me­chan­i­cal de­sign. How­ever, dur­ing the rf pulse ramp up or the ma­chine sys­tem cool-down process, when the field in the cav­ity changes rapidly, tran­sient ef­fects need to be taken into ac­count. A par­al­lel time do­main ther­mal solver has been de­vel­oped in the fi­nite el­e­ment multi-physics code suite ACE3P with in­te­grated elec­tro­mag­netic, ther­mal and me­chan­i­cal mod­el­ing ca­pa­bil­i­ties. The im­ple­men­ta­tion takes ad­van­tage of the par­al­lel com­pu­ta­tion in­fra­struc­ture of ACE3P and shares most of the in­gre­di­ents in mesh gen­er­a­tion, ma­trix as­sem­bly, time ad­vance­ment scheme and post­pro­cess­ing. In this paper, we will out­line the fi­nite el­e­ment for­mu­la­tion of the tran­sient ther­mal prob­lem and ver­ify the im­ple­men­ta­tion against an­a­lyt­i­cal so­lu­tions and ex­ist­ing nu­mer­i­cal re­sults. The ther­mal solver has also been cou­pled to ACE3P me­chan­i­cal solver, al­low­ing stress and strain analy­sis dur­ing the tran­sient stage. Ap­pli­ca­tion of the tran­sient ther­mal solver to re­al­is­tic ac­cel­er­a­tor cav­i­ties will be pre­sented. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB248  
About • paper received ※ 19 May 2021       paper accepted ※ 18 August 2021       issue date ※ 25 August 2021  
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TUPAB254 Limiting Coherent Longitudinal Beam Oscillations in the EIC Electron Storage Ring feedback, electron, emittance, hadron 2046
 
  • B. Podobedov
    Brookhaven National Laboratory (BNL), Electron-Ion Collider, Upton, New York, USA
  • M. Blaskiewicz
    BNL, Upton, New York, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
We study co­her­ent lon­gi­tu­di­nal beam os­cil­la­tions in the EIC elec­tron stor­age ring (ESR). We show that to avoid un­ac­cept­able hadron emit­tance growth due to fi­nite cross­ing angle, the am­pli­tude of these os­cil­la­tions needs to be lim­ited to a frac­tion of a mil­lime­ter. Using an an­a­lyt­i­cal model we es­ti­mate the am­pli­tude of these os­cil­la­tions under the two sce­nar­ios: 1) the beam is pas­sively sta­ble and the os­cil­la­tions are dri­ven by RF phase noise only; 2) a cou­pled-bunch in­sta­bil­ity, presently ex­pected in the ESR, is damped by a lon­gi­tu­di­nal feed­back sys­tem. We show that, for the 2nd sce­nario, com­fort­able spec­i­fi­ca­tions for RF phase noise and feed­back sen­sor noise will be suf­fi­cient to main­tain the os­cil­la­tion am­pli­tude within the re­quired lim­its. 		 
poster icon Poster TUPAB254 [1.347 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB254  
About • paper received ※ 12 May 2021       paper accepted ※ 18 June 2021       issue date ※ 26 August 2021  
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TUPAB256 Investigation of Damping Effects of the Crab Cavity Noise Induced Emittance Growth emittance, simulation, impedance, experiment 2054
 
  • N. Triantafyllou, L.R. Carver, A. Wolski
    The University of Liverpool, Liverpool, United Kingdom
  • F. Antoniou, H. Bartosik, P. Baudrenghien, X. Buffat, R. Calaga, Y. Papaphilippou, N. Triantafyllou
    CERN, Meyrin, Switzerland
  • L.R. Carver
    ESRF, Grenoble, France
  • T. Mastoridis
    CalPoly, San Luis Obispo, California, USA
  
  Crab cav­i­ties will be in­stalled at the two main in­ter­ac­tion points (IP1 and IP5) of the High Lu­mi­nos­ity LHC (HL-LHC) in order to min­i­mize the geo­met­ric re­duc­tion of the lu­mi­nos­ity due to the cross­ing angle. Two pro­to­type crab cav­i­ties have been in­stalled into the SPS ma­chine and were tested with a pro­ton beam in 2018, to study the ex­pected emit­tance growth in­duced by RF noise. The mea­sured emit­tance growth was found to be a fac­tor 2-3 lower than pre­dicted from the avail­able an­a­lyt­i­cal and com­pu­ta­tional mod­els. Damp­ing mech­a­nisms from the trans­verse im­ped­ance, which is not in­cluded in the avail­able the­o­ries, are stud­ied as a pos­si­ble ex­pla­na­tion for the ob­served dis­crep­ancy.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB256  
About • paper received ※ 18 May 2021       paper accepted ※ 18 June 2021       issue date ※ 23 August 2021  
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TUPAB261 The Ferrite Loaded Cavity Impedance Simulation impedance, simulation, MMI, synchrotron 2070
 
  • L. Huang, X. Li, S. Wang, S.Y. Xu
    IHEP, Beijing, People’s Republic of China
  • B. Wu
    IHEP CSNS, Guangdong Province, People’s Republic of China
  
  Funding: Work supported by NNSF of China: N0. U1832210
The Rapid Cy­cling Syn­chro­tron of the China Spal­la­tion Neu­tron Source is a high-in­ten­sity pro­ton ac­cel­er­a­tor, it ac­cu­mu­lates the 80 MeV pro­ton beam and ac­cel­er­ates it to 1.6 GeV in 20 ms. The trans­verse cou­pling bunch in­sta­bil­ity is ob­served in beam com­mis­sion­ing. The source has been in­ves­ti­gat­ing from the com­mis­sion­ing. The RF ac­cel­er­a­tion sys­tem con­sists of eight fer­rite-loaded cav­i­ties. The im­ped­ance is sim­u­lated and there is a nar­row-band im­ped­ance of the fer­rite cav­ity at about 17 MHz 		 
poster icon Poster TUPAB261 [1.145 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB261  
About • paper received ※ 13 May 2021       paper accepted ※ 31 May 2021       issue date ※ 28 August 2021  
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TUPAB263 The Phase Loop Status of the RF System in CSNS/RCS proton, feedback, space-charge, MMI 2076
 
  • L. Huang, X. Li, S. Wang
    IHEP, Beijing, People’s Republic of China
  • M.T. Li, H.Y. Liu
    IHEP CSNS, Guangdong Province, People’s Republic of China
  • Y. Liu
    DNSC, Dongguan, People’s Republic of China
  
  The Rapid Cy­cling Syn­chro­tron (RCS) of the China Spal­la­tion Neu­tron Source (CSNS) is a high in­ten­sity pro­ton ac­cel­er­a­tor. The ac­cel­er­a­tion sys­tem con­sists of eight fer­rite loaded cav­i­ties. The RCS is the space charge dom­i­nant ma­chine and it is mit­i­gated through the bunch fac­tor op­ti­miza­tion in the beam com­mis­sion­ing, so the in­jected beam will oc­cupy a larger bucket size and un­avoid­able mis­match with the bucket, thus the di­pole os­cil­la­tion is ex­cited. The phase loop scheme is de­signed to re­strict the os­cil­la­tion in the RF sys­tem, but the trans­mis­sion ef­fi­ciency is re­duced by the phase loop and the bunch fac­tor also in­creases, so the phase loop scheme is stud­ied. To keep the phase loop but also main­tain the trans­mis­sion ef­fi­ciency, we op­ti­mized the orig­i­nal phase loop scheme, but the beam loss still in­creases small when the loop on.  
poster icon Poster TUPAB263 [1.548 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB263  
About • paper received ※ 13 May 2021       paper accepted ※ 02 June 2021       issue date ※ 24 August 2021  
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TUPAB265 Bunch Lengthening of the HALF Storage Ring in the Presence of Passive Harmonic Cavities storage-ring, simulation, damping, emittance 2082
 
  • T.L. He, Z.H. Bai, G.Y. Feng, W. Li, W.W. Li, G. Liu, L. Wang, H. Xu, S.C. Zhang
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
  
  A pas­sive 3rd har­monic RF sys­tem, being nec­es­sary for the Hefei Ad­vanced Light Fa­cil­ity (HALF) stor­age ring under de­sign, will be em­ployed to lengthen the bunches for sup­press­ing the in­tra­beam scat­ter­ing and im­prov­ing the beam life­time. How­ever, the tran­sient beam load­ing due to the fun­da­men­tal mode may sig­nif­i­cantly re­duce the bunch length­en­ing. Since the scale of tran­sient ef­fects is pro­por­tional to R/Q, the ef­fects of R/Q on bunch length­en­ing, in uni­form fill pat­tern with the near-op­ti­mum con­di­tion ful­filled, are an­a­lyzed by multi­bunches mul­ti­par­ti­cles track­ing sim­u­la­tion. It in­di­cates that the pas­sive su­per­con­duct­ing har­monic cav­ity with a lower R/Q is pre­ferred by HALF.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB265  
About • paper received ※ 16 May 2021       paper accepted ※ 18 June 2021       issue date ※ 21 August 2021  
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TUPAB266 Periodic Transient Beam Loading Effects Predicted by a Semi-Analytical Method beam-loading, storage-ring, wakefield, simulation 2086
 
  • T.L. He, Z.H. Bai, G. Feng, W. Li, W.W. Li, G. Liu, L. Wang, H. Xu, S.C. Zhang
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
  
  In this paper, we im­prove a semi-an­a­lyt­i­cal method, which can be not only used for bunch length­en­ing under equi­lib­rium con­di­tions, but also ap­plied to the pre­dic­tion of a pe­ri­odic tran­sient beam load­ing ef­fect. This pe­ri­odic tran­sient is in­duced by the pres­ence of the pas­sive har­monic cav­ity and might be en­coun­tered under spe­cific con­di­tions for a ul­tra-low emit­tance stor­age ring with a higher beam cur­rent.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB266  
About • paper received ※ 16 May 2021       paper accepted ※ 21 June 2021       issue date ※ 10 August 2021  
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TUPAB272 Observation of Long-Range Wakefield Effects Generated in an Off-Resonance Tesla-Type Cavity HOM, electron, resonance, wakefield 2101
 
  • A.H. Lumpkin, D.R. Edstrom, A. Lunin, P.S. Prieto, J. Ruan, R.M. Thurman-Keup
    Fermilab, Batavia, Illinois, USA
  • J.A. Diaz Cruz
    UNM-ECE, Albuquerque, USA
  • J.A. Diaz Cruz, B.T. Jacobson, J.P. Sikora
    SLAC, Menlo Park, California, USA
  
  Funding: Work supported 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 in­ter­est in con­trol­ling emit­tance di­lu­tion ef­fects due to off-axis beam trans­port in ac­cel­er­a­tor cav­i­ties and the re­sult­ing dipo­lar modes is es­pe­cially im­por­tant for the fa­cil­i­ties with lower emit­tance beams. The Fer­mi­lab Ac­cel­er­a­tor Sci­ence and Tech­nol­ogy (FAST) fa­cil­ity has a unique con­fig­u­ra­tion of two sin­gle cav­i­ties after the pho­to­cath­ode rf gun fol­lowed by a cry­omod­ule. The sec­ond cap­ture cav­ity (CC2) was run 15 kHz off res­o­nance and with­out rf power while a 25-MeV beam was in­jected into it. The beam cen­troid ef­fects were tracked by 10 rf but­ton BPMs with bunch-by-bunch po­si­tion read­out ca­pa­bil­ity down­stream in a 12-m drift. Pos­si­ble LRW ef­fects seemed to dom­i­nate our pre­vi­ously ob­served near-res­o­nant HOM ef­fects at mode 14 in this cav­ity. This mode also shifted in fre­quency com­pared to that of the tuned case based on di­rect mea­sure­ments. Sub­macropulse ver­ti­cal po­si­tion slew­ing of 1400 mi­crons at 11 m down­stream was ob­served with a 125 pC/bunch, 50 bunches per macropulse, and 25-MeV beam. The y-po­si­tion slew am­pli­tudes as a func­tion of z were also mea­sured. Hor­i­zon­tal po­si­tions also showed a slew ef­fect. Both are emit­tance-di­lu­tion ef­fects which one wants to mit­i­gate. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB272  
About • paper received ※ 18 May 2021       paper accepted ※ 09 June 2021       issue date ※ 16 August 2021  
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TUPAB273 Observations on Submicropulse Electron-Beam Effects From Short-Range Wakefields in Tesla-Type Superconducting Rf Cavities electron, wakefield, laser, HOM 2105
 
  • A.H. Lumpkin, D.R. Edstrom, P.S. Prieto, J. Ruan, R.M. Thurman-Keup
    Fermilab, Batavia, Illinois, USA
  • J.A. Diaz Cruz
    UNM-ECE, Albuquerque, USA
  • J.A. Diaz Cruz, A.L. Edelen, B.T. Jacobson, F. Zhou
    SLAC, Menlo Park, California, USA
  
  Funding: Work supported 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.
In pre­vi­ous ex­per­i­ments at the Fer­mi­lab Ac­cel­er­a­tor Sci­ence and Tech­nol­ogy (FAST) fa­cil­ity, the ef­fects of higher-or­der modes (HOMs) in TESLA-type cav­i­ties on sub­macropulse cen­troid mo­tion were elu­ci­dated*. We now have ex­tended our in­ves­ti­ga­tions to short-range wake­fields (SRWs) in these cav­i­ties. The lat­ter re­sult in sub­mi­cropulse ef­fects where the trans­verse wake­fields cause head-tail cen­troid shifts. We used a Hama­matsu C5680 UV-vis­i­ble syn­chroscan streak cam­era to syn­chro­nously sum the OTR from each of the 50 mi­cropulses in the macropulse. We gen­er­ated the y-t ef­fect in the 41-MeV beam by pur­posely steer­ing the beam off axis in y at the en­trance of the first cap­ture cav­ity. The head-tail trans­verse kicks within the 11-ps-long mi­cropulses of 500 pC each were ob­served at the 100-mi­cron level for steer­ing off-axis in one cav­ity and sev­eral 100 mi­crons for two cav­i­ties. These SRW re­sults will be com­pared to sim­u­la­tions from the ASTRA model of a sin­gle mi­cropulse in FAST. Since the SRW kicks go in­versely with en­ergy, these emit­tance-di­lu­tion ef­fects are par­tic­u­larly rel­e­vant to the LCLS-II in­jec­tor com­mis­sion­ing plans where <1 MeV beam will be in­jected into a TESLA-type cry­omod­ule.
* A.H. Lumpkin et al, Phys. Rev. Accel. and Beams 23, 054401 (2020). 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB273  
About • paper received ※ 18 May 2021       paper accepted ※ 09 June 2021       issue date ※ 02 September 2021  
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TUPAB274 Investigations of Long-Range Wakefield Effects in a TESLA-type Cryomodule at FAST HOM, electron, cryomodule, wakefield 2109
 
  • A.H. Lumpkin, D.R. Edstrom, P.S. Prieto, J. Ruan, R.M. Thurman-Keup
    Fermilab, Batavia, Illinois, USA
  • J.A. Diaz Cruz
    UNM-ECE, Albuquerque, USA
  • J.A. Diaz Cruz, B.T. Jacobson, J.P. Sikora, F. Zhou
    SLAC, Menlo Park, California, USA
  
  Funding: *Work supported 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 preser­va­tion of low emit­tance of elec­tron beams dur­ing trans­port in the ac­cel­er­at­ing struc­tures of large fa­cil­i­ties is an on­go­ing chal­lenge. In the cases of the TESLA-type su­per­con­duct­ing rf cav­i­ties cur­rently used in the Eu­ro­pean X-ray Free-elec­tron Laser (XFEL) and the un­der-con­struc­tion Linac Co­her­ent Light Source up­grade (LCLS-II), off-axis beam trans­port may re­sult in emit­tance di­lu­tion due to trans­verse long-range wake­fields (LRWs) and short-range wake­fields (SRW)***. To in­ves­ti­gate such ef­fects, ex­per­i­ments were per­formed at the Fer­mi­lab Ac­cel­er­a­tor Sci­ence and Tech­nol­ogy (FAST) fa­cil­ity with its unique con­fig­u­ra­tion of two TESLA-type cav­i­ties after the pho­to­cath­ode rf gun fol­lowed by an 8-cav­ity cry­omod­ule CM). We gen­er­ated beam tra­jec­tory changes with the H/V125 cor­rec­tor set lo­cated 4 m up­stream of the cry­omod­ule. At 125 pC/bunch, 50 bunches, 25-MeV input, and 100-MeV exit en­ergy, we ob­served for the first time sub­macropulse po­si­tion slews of up to 500 mi­crons at lo­ca­tions ~3 m after the CM and a cen­troid os­cil­la­tion at a dif­fer­ence fre­quency of 240 kHz fur­ther down­stream. Both are emit­tance-di­lu­tion ef­fects which we mit­i­gated with se­lec­tive up­stream beam steer­ing.
***W.K.H. Panofsky and M. Bander, Rev. Sci. Instr. 39, 206 (1968). 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB274  
About • paper received ※ 18 May 2021       paper accepted ※ 09 June 2021       issue date ※ 18 August 2021  
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TUPAB292 Automation of the ReAccelerator Linac Phasing detector, controls, interface, linac 2170
 
  • D.J. Barofsky, A.I. Henriques, T.J. Kabana, A.S. Plastun
    FRIB, East Lansing, Michigan, USA
  • D.B. Crisp, A. Lapierre, S. Nash, A.C.C. Villari
    NSCL, East Lansing, Michigan, USA
  
  Funding: This work is supported by the National Science Foundation under Grant No. PHY-1565546
The ReAc­cel­er­a­tor (ReA) at the Na­tional Su­per­con­duct­ing Cy­clotron Lab­o­ra­tory at Michi­gan State Uni­ver­sity is a unique fa­cil­ity, as it of­fers the pos­si­bil­ity to reac­cel­er­ate not only sta­ble, but rare-iso­tope beams pro­duced by fast-pro­jec­tile frag­men­ta­tion or fis­sion. At ReA, beams are ac­cel­er­ated using a Ra­dio-Fre­quency-Quadru­pole and a su­per­con­duct­ing lin­ear ac­cel­er­a­tor be­fore being de­liv­ered to ex­per­i­ments. Beam prepa­ra­tion time plays a major role in the avail­abil­ity of beams to ex­per­i­ments. One of the major time con­sum­ing tasks is the linac phas­ing, since there are 23 res­onator cav­i­ties to be phased, usu­ally with very low beam in­ten­si­ties. This pro­ce­dure was au­to­mated using a com­bi­na­tion of EPICS (Ex­per­i­men­tal Physics and In­dus­trial Con­trols Sys­tem) In/Out­put Con­trollers (IOCs) and IOC trig­gered scripts to scan the res­onator phase delay and mea­sure the change in beam en­ergy. We have de­vel­oped user-friendly tools to phase the linac, which have been tested, mak­ing the task of phas­ing sub­stan­tially eas­ier. In this pre­sen­ta­tion, we will pre­sent our method­ol­ogy, chal­lenges faced, tools de­vel­oped, and ini­tial re­sults of the ap­pli­ca­tion for au­tomat­ing the phas­ing of the ReA linac. 		 
poster icon Poster TUPAB292 [1.140 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB292  
About • paper received ※ 19 May 2021       paper accepted ※ 02 June 2021       issue date ※ 11 August 2021  
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TUPAB302 Arrival Time Stabilization at Flash Using the Bunch Arrival Corrector Cavity (BACCA) electron, feedback, laser, SRF 2194
 
  • B. Lautenschlager, L. Butkowski, M.K. Czwalinna, B. Dursun, M. Hierholzer, S. Pfeiffer, H. Schlarb, Ch. Schmidt
    DESY, Hamburg, Germany
  
  For pump-probe and seed­ing ex­per­i­ments at free elec­tron lasers, a fem­tosec­ond pre­cise bunch ar­rival time sta­bil­ity is manda­tory. To sta­bi­lize the ar­rival times a fast lon­gi­tu­di­nal intra bunch-train feed­back (L-IBFB) using bunch ar­rival time mon­i­tors is ap­plied. The elec­tron bunch en­ergy prior to a bunch com­pres­sion chi­cane is mod­u­lated by su­per­con­duct­ing radio fre­quency (SRF) cav­i­ties to com­pen­sate fast ar­rival time fluc­tu­a­tions of the sub­se­quent bunches. A broad­band nor­mal con­duct­ing RF cav­ity was in­stalled in front of the first bunch com­pres­sion chi­cane at FLASH. The L-IBFB uses the nor­mal con­duct­ing cav­ity for small but fast en­ergy cor­rec­tions to­gether with the SRF cav­i­ties for larger and slower cor­rec­tions. Cur­rent mea­sure­ments show ar­rival time sta­bil­i­ties of the elec­tron bunches to­wards 5 fs (rms) at the end of the linac, if the nor­mal con­duct­ing cav­ity acts to­gether with the SRF cav­i­ties in the L-IBFB sys­tem.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB302  
About • paper received ※ 19 May 2021       paper accepted ※ 23 June 2021       issue date ※ 12 August 2021  
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TUPAB306 Status of Beam-Based Feedback Research and Development for Continuous Wave SRF Linac ELBE controls, electron, feedback, LLRF 2200
 
  • A. Maalberg, M. Kuntzsch
    HZDR, Dresden, Germany
  • E. Petlenkov
    TalTech, Tallinn, Estonia
  
  The su­per­con­duct­ing elec­tron lin­ear ac­cel­er­a­tor ELBE at Helmholtz-Zen­trum Dres­den-Rossendorf is a ver­sa­tile light source op­er­ated in con­tin­u­ous wave mode. As the de­mand on the beam sta­bil­ity in­creases, the im­prove­ment of the beam con­trol schemes cur­rently in­stalled at ELBE be­comes highly rel­e­vant. This im­prove­ment can be achieved by an up­grade of the ex­ist­ing dig­i­tal Mi­croTCA.4-based LLRF con­trol scheme by beam-based feed­back. By pre­sent­ing both the de­sign and im­ple­men­ta­tion de­tails of the new con­trol scheme this con­tri­bu­tion re­ports the sta­tus of the work in progress.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB306  
About • paper received ※ 19 May 2021       paper accepted ※ 21 June 2021       issue date ※ 19 August 2021  
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TUPAB328 Machine Learning for Time Series Prediction of an Accelerator Beam to Recognize Equipment Malfunction SRF, linac, ion-source, neutron 2272
 
  • C.C. Peters
    ORNL RAD, Oak Ridge, Tennessee, USA
  • W. Blokland, D.L. Brown, F. Liu, C.D. Long, D. Lu, P. Ramuhalli, D.E. Womble, J. Zhang, A.P. Zhukov
    ORNL, Oak Ridge, Tennessee, USA
  
  Funding: ORNL is managed by UT-Battelle, LLC, under contract DE-AC05- 00OR22725 for the U.S. Department of Energy.
The Spal­la­tion Neu­tron Source (SNS) is an ac­cel­er­a­tor based pulsed neu­tron source based on a 1 GeV pulsed pro­ton Su­per­con­duct­ing Radio Fre­quency (SRF) lin­ear ac­cel­er­a­tor (linac). Since be­gin­ning high power beam op­er­a­tion in 2006 cor­re­la­tions have been found link­ing abrupt beam loss events to SRF cav­ity in­sta­bil­i­ties. With the planned up­grades to dou­ble the beam power we ex­pect in­creased rates of degra­da­tion and the im­por­tance of min­i­miz­ing these beam loss events will be­come ever more im­por­tant. To fur­ther limit degra­da­tion, we are de­vel­op­ing ma­chine learn­ing ap­proaches to mon­i­tor the beam and to de­tect, pre­dict and pre­vent beam loss events. Ini­tial re­search has shown that pre­cur­sors to beam loss events are de­tectable. The ini­tial steps are to use ML-based clas­si­fi­ca­tion to rec­og­nize anom­alies and to use Long Short-Term Mem­ory (LSTM) au­toen­coders to pre­dict beam loss. In this paper, we de­scribe re­cent progress in ap­ply­ing ma­chine learn­ing for rec­og­niz­ing anom­alies and pre­dict­ing beam loss and pre­sent ini­tial re­sults of our re­search using ac­quired data from dif­fer­ent di­ag­nos­tics and the Ma­chine Pro­tec­tion Sys­tem (MPS). 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB328  
About • paper received ※ 23 May 2021       paper accepted ※ 28 May 2021       issue date ※ 23 August 2021  
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TUPAB329 Pattern Based Parameter Setup of the SNS Linac linac, DTL, operation, beam-losses 2276
 
  • C.C. Peters
    ORNL RAD, Oak Ridge, Tennessee, USA
  • A.P. Shishlo
    ORNL, Oak Ridge, Tennessee, USA
  
  Funding: ORNL is managed by UT-Battelle, LLC, under contract DE-AC05- 00OR22725 for the U.S. Department of Energy.
The­o­ret­i­cal and prac­ti­cal as­pects of beam tun­ing pro­ce­dures used for the SNS linac are dis­cussed. The SNS linac in­cludes two sec­tions of beam ac­cel­er­a­tion. Ac­cel­er­a­tion in the first sec­tion up to 185.5 MeV is done with a room tem­per­a­ture cop­per linac which con­sists of both Drift Tube Linac (DTL) and Cou­pled Cav­ity Linac (CCL) Radio Fre­quency (RF) cav­i­ties. The sec­ond sec­tion con­sists of 81 Su­per­con­duct­ing RF (SRF) cav­i­ties which ac­cel­er­ate the beam to the final beam en­ergy of 1 GeV. The linac is cur­rently ca­pa­ble of de­liv­er­ing an av­er­age beam power out­put of 1.44 MW with typ­i­cal yearly op­er­at­ing hours of around 4500 hours. Due to the high power out­put and high avail­abil­ity of the linac, ac­ti­va­tion of ac­cel­er­a­tor equip­ment is a sig­nif­i­cant con­cern. The linac tun­ing process con­sists of three stages: model based setup of am­pli­tudes and phases of the RF cav­i­ties, em­pir­i­cal beam loss re­duc­tion, and then doc­u­men­ta­tion of the final am­pli­tudes and phases of RF cav­i­ties after the em­pir­i­cal tun­ing. The final step is needed to en­sure fast re­cov­ery from an SRF cav­ity fail­ure. This paper dis­cusses mod­els, al­go­rithms, di­ag­nos­tic tools, soft­ware, and prac­tices that are used for these stages. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB329  
About • paper received ※ 22 May 2021       paper accepted ※ 28 May 2021       issue date ※ 26 August 2021  
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TUPAB333 Status of PIP-II 650 MHz Prototype Dressed Cavity Qualification SRF, cryomodule, status, superconductivity 2279
 
  • G.V. Eremeev, D.J. Bice, C. Boffo, S.K. Chandrasekaran, S. Cheban, F. Furuta, I.V. Gonin, C.J. Grimm, S. Kazakov, T.N. Khabiboulline, A. Lunin, M. Martinello, N. Nigam, J.P. Ozelis, Y.M. Pischalnikov, K.S. Premo, O.V. Prokofiev, O.V. Pronitchev, G.V. Romanov, N. Solyak, A.I. Sukhanov, G. Wu
    Fermilab, Batavia, Illinois, USA
  • M. Bagre, V. Jain, A. Puntambekar, S. Raghvendra, P. Shrivastava
    RRCAT, Indore (M.P.), India
  • P. Bhattacharyya, S. Ghosh, S. Seth
    VECC, Kolkata, India
  • R. Kumar
    BARC, Mumbai, India
  • J. Lewis, P.A. McIntosh, A.E. Wheelhouse
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • C. Pagani, R. Paparella
    INFN/LASA, Segrate (MI), Italy
  • C. Pagani
    Università degli Studi di Milano & INFN, Segrate, Italy
  • T. Reid
    ANL, Lemont, Illinois, USA
  • A.D. Shabalina
    STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
  
  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.
Low-beta and high-beta sec­tions of PIP-II linac will use nine low-beta cry­omod­ules with four cav­i­ties each and four high-beta cry­omod­ules with six cav­i­ties each. These cav­i­ties will be pro­duced and qual­i­fied in col­lab­o­ra­tion be­tween Fer­mi­lab and the in­ter­na­tional part­ner labs. Prior to their in­stal­la­tion into pro­to­type cry­omod­ules, sev­eral dressed cav­i­ties, which in­clude jack­eted cav­i­ties, high power cou­plers, and tuners, will be qual­i­fied in STC hor­i­zon­tal test bed at Fer­mi­lab. After qual­i­fi­ca­tion of bare β = 0.9 cav­i­ties at Fer­mi­lab, sev­eral pre-pro­duc­tion β = 0.92 and β = 0.61 cav­i­ties have been and are being fab­ri­cated and qual­i­fied. Pro­cure­ments have also been started for high power cou­plers and tuners. In this con­tri­bu­tion we pre­sent the cur­rent sta­tus of pro­to­type dressed cav­ity qual­i­fi­ca­tion for PIP-II. 		 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB333  
About • paper received ※ 23 May 2021       paper accepted ※ 19 July 2021       issue date ※ 25 August 2021  
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TUPAB338 Surface Roughness Reduction of Nb3Sn Thin Films via Laser Annealing for Superconducting Radio-Frequency Cavities laser, SRF, superconductivity, HOM 2283
 
  • Z. Sun, M. Ge, M. Liepe, T.E. Oseroff, R.D. Porter
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • A.B. Connolly, M.O. Thompson
    Cornell University, Ithaca, USA
  
  Su­per­con­duct­ing radio fre­quency (SRF) cav­i­ties, a key com­po­nent of par­ti­cle ac­cel­er­a­tors, await new SRF ma­te­ri­als be­yond the state-of-the-art nio­bium. Nb3Sn is one of the most com­pet­i­tive can­di­dates, since it in­creases the su­per­heat­ing field, al­lows the op­er­a­tion tem­per­a­ture up to 4K, and im­proves cav­ity ef­fi­ciency. Sur­face rough­ness and grain bound­aries, how­ever, sig­nif­i­cantly af­fect the RF per­for­mance of cur­rent Nb3Sn cav­i­ties. Here, we ex­plore a post laser an­neal­ing tech­nique to re­duce the sur­face rough­ness. In doing so, we de­posited a TiN laser-ab­sorber on Nb3Sn and Nb sur­faces, and then an­nealed the sam­ples by laser scan­ning via dif­fer­ent laser sys­tems. The Nb3Sn sur­face rough­ness was min­i­mized to 101 nm (Ra) by laser an­neal­ing via 308 nm, 35 ns pulses. Sur­face imag­ing and Fourier analy­sis re­vealed laser an­neal­ing is able to re­move sharp edges and <1 um wave­length fea­tures.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB338  
About • paper received ※ 20 May 2021       paper accepted ※ 09 June 2021       issue date ※ 19 August 2021  
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TUPAB339 High Power Test of the Antenna Adjustable Power Coupler for 325 MHz Superconducting Cavities vacuum, multipactoring, electron, pick-up 2286
 
  • J.Y. Yoon, E.-S. Kim, C.S. Park, S.H. Park
    KUS, Sejong, Republic of Korea
  • J. Bahng
    Korea University Sejong Campus, Sejong, Republic of Korea
  • E. Kako
    KEK, Ibaraki, Japan
  • K.R. Kim
    PAL, Pohang, Republic of Korea
  
  Funding: The Ministry of Education (South Korea)
The power cou­pler is de­vel­op­ment at Korea Uni­ver­sity for a Sin­gle Spoke Res­onator (SSR) of heavy ion ac­cel­er­a­tor. Our power cou­pler is a coax­ial ca­pac­i­tive type based on a con­ven­tional 3-1/8 inch elec­tronic in­dus­tries al­liance (EIA) 50 Ω coax­ial trans­mis­sion line with a ti­ta­nium ni­tride (TiN) coated sin­gle ce­ramic win­dow. A high power test is rec­tan­gu­lar test cav­ity with high vac­uum and var­i­ous mea­sur­ing equip­ment, such as an arc de­tec­tor, a power meter, and an elec­tron pick-up probe. The in­ter­lock sys­tem under vac­uum and arc in­stru­men­ta­tions pre­vent the RF win­dow from break­ing the power cou­pler win­dow dur­ing the high power test. We con­duct high power tests for more than 12 hrs at 12 kW in a 325 MHz con­ti­nous wave (CW) mode to ver­ify the per­for­mance of the de­signed power cou­pler.
*Superconducting, *Power Coupler 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB339  
About • paper received ※ 12 May 2021       paper accepted ※ 21 June 2021       issue date ※ 22 August 2021  
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TUPAB340 Design of the Magnetic Shielding for 166 MHz and 500 MHz Superconducting RF Cavities at High Energy Photon Source shielding, simulation, photon, superconducting-cavity 2289
 
  • L. Guo, Y. Chen, J. Li, Z.Q. Li, Q. Ma, P. Zhang, X.Y. Zhang, H.J. Zheng
    IHEP, Beijing, People’s Republic of China
  
  Funding: This work was supported by High Energy Photon Source, a major national science and technology infrastructure in China.
Five 166 MHz quar­ter-wave β=1 su­per­con­duct­ing cav­i­ties and two 500 MHz sin­gle-cell el­lip­ti­cal su­per­con­duct­ing cav­i­ties have been de­signed for the stor­age ring of High En­ergy Pho­ton Source (HEPS). It is nec­es­sary to shield mag­netic field for su­per­con­duct­ing cav­i­ties to re­duce the resid­ual sur­face re­sis­tance due to mag­netic flux trap­ping dur­ing cav­ity cool down. The mag­netic shield­ing for both 166 MHz and 500 MHz su­per­con­duct­ing cav­i­ties have been de­signed. The resid­ual mag­netic field in­side the cav­i­ties have been cal­cu­lated by using Opera-3D sim­u­la­tion soft­ware. The ge­o­graphic lo­ca­tion of the cav­ity being in­stalled at the HEPS site and the fringe field of the up­stream mag­net are con­sid­ered. These are re­ported in this paper. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB340  
About • paper received ※ 18 May 2021       paper accepted ※ 17 June 2021       issue date ※ 20 August 2021  
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TUPAB341 Optimization of Two-Cell Cavities for the W and H Working Points of the FCC-ee Considering Higher-Order Mode Effects HOM, impedance, damping, ECR 2292
 
  • S. Udongwo, S.G. Zadeh, U. van Rienen
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
  • R. Calaga
    CERN, Meyrin, Switzerland
  
  Funding: The European Organization for Nuclear Research (CERN)
The lep­ton col­lider of the fu­ture cir­cu­lar col­lider (FCC-ee) aims at con­duct­ing pre­ci­sion mea­sure­ments on the Z, W, and H bosons and the top quark. The pre­sent RF base­line con­sid­ers sin­gle-cell cav­i­ties at 400 MHz for the high cur­rent Z-pole work­ing point, four-cell 400 MHz cav­i­ties for the W and H work­ing points, and a hy­brid RF sys­tem com­posed of four-cell 400 MHz and five-cell 800 MHz cav­i­ties for the high en­ergy tt work­ing point. The W work­ing point has shown lim­i­ta­tions in the achiev­able HOM damp­ing for beam sta­bil­ity re­quire­ments using four-cell cav­i­ties. A two-cell cav­ity is stud­ied as an al­ter­na­tive sce­nario for the cur­rent W- and H-RF se­tups with a spe­cial focus on HOM damp­ing dur­ing the op­ti­miza­tion of the RF geom­e­try. 		 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB341  
About • paper received ※ 19 May 2021       paper accepted ※ 21 June 2021       issue date ※ 02 September 2021  
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TUPAB342 Preliminary Cryogenic Cold Test Results of the First 9-Cell LSF Shape Cavity niobium, SRF, multipactoring, laser 2296
 
  • R.L. Geng, W.A. Clemens, R.S. Williams
    JLab, Newport News, Virginia, USA
  • S.A. Belomestnykh
    Fermilab, Batavia, Illinois, USA
  • Y. Fuwa
    JAEA/J-PARC, Tokai-mura, Japan
  • H. Hayano
    KEK, Ibaraki, Japan
  • Y. Iwashita
    Kyoto ICR, Uji, Kyoto, Japan
  • Z. Li
    SLAC, Menlo Park, California, USA
  • V.D. Shemelin
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Supplemental support by US-Japan Collaboration on HEP.
Fol­low­ing suc­cess­ful pro­to­typ­ing and test­ing of sin­gle- & 5-cell LSF shape cav­i­ties *, **, the first 9-cell LSF shape cav­ity LSF9-1 was suc­cess­fully con­structed using an in­no­v­a­tive process at JLab with the in-house fa­cil­i­ties. The cav­ity was then shipped to KEK for post-fab­ri­ca­tion me­chan­i­cal ad­just­ment and ILC TDR style treat­ment and sur­face pro­cess­ing. Cold test­ing was car­ried out at the JLab VTA fa­cil­ity, in­stru­mented with a suite of Kyoto in­stru­ments. Fa­vor­able val­ues for the bath pres­sure de­tun­ing sen­si­tiv­ity and Lorentz force de­tun­ing co­ef­fi­cient were ex­per­i­men­tally mea­sured, val­i­dat­ing the de­sign im­prove­ment in cell stiff­en­ers. Pass-band mea­sure­ments in­di­cate 4 out of 9 cells reach­ing gra­di­ent ca­pa­bil­ity of > 45 MV/m, in­clud­ing 2 cells reach­ing 51 MV/m. Cor­nell OST de­tec­tors iden­ti­fied the cell and lo­ca­tion re­spon­si­ble for the cur­rent hard quench limit. Mul­ti­pact­ing-like bar­ri­ers ob­served in end cells are in­ves­ti­gated both an­a­lyt­i­cally and nu­mer­i­cally. The cav­ity was shipped to FNAL and re­ceived a light EP at the joint ANL/FNAL fa­cil­ity for fur­ther cold test­ing at Jlab. Two new 9-cell LSF cav­i­ties are being con­structed in­clud­ing one made of large-grain nio­bium ma­te­r­ial.
* R. L. Geng et al.,WEPWI013, IPAC15.
** R. L. Geng et al., MOP064, SRF’19.
 		 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB342  
About • paper received ※ 09 May 2021       paper accepted ※ 14 June 2021       issue date ※ 30 August 2021  
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TUPAB343 Final Design Studies for the VSR DEMO 1.5 GHz Coupler multipactoring, SRF, operation, electron 2300
 
  • E. Sharples-Milne, V. Dürr, P. Echevarria, J. Knobloch, A. Neumann, A.V. Vélez
    HZB, Berlin, Germany
  
  With the 1.5 GHz cou­plers for the Vari­able pulse length Stor­age Ring (VSR) DEMO now in the man­u­fac­tur­ing stages, the stud­ies that led to the final cou­pler de­sign will be pre­sented. The sys­tem spe­cific con­straints and de­sign mod­i­fi­ca­tions that com­bat the chal­lenges of ther­mo­me­chan­i­cal stresses, higher order mode (HOM) prop­a­ga­tion and di­men­sional con­straints are ex­plored. This in­cludes S-Pa­ra­me­ter analy­sis, an in-depth study of the cou­pling fac­tor, and mul­ti­pact­ing stud­ies for the av­er­age (1.5 kW) and peak (16 kW) power.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB343  
About • paper received ※ 19 May 2021       paper accepted ※ 17 June 2021       issue date ※ 01 September 2021  
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TUPAB344 Evaluation of Anisotropic Magnetoresistive (AMR) Sensors for a Magnetic Field Scanning System for SRF Cavities SRF, experiment, niobium, MMI 2304
 
  • I.P. Parajuli, G. Ciovati, J.R. Delayen, A.V. Gurevich
    ODU, Norfolk, Virginia, USA
  • G. Ciovati, J.R. Delayen
    JLab, Newport News, Virginia, USA
  
  Funding: Work supported by NSF Grant 100614-010. G. C. is supported by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
One of the sig­nif­i­cant causes of resid­ual losses in su­per­con­duct­ing ra­dio-fre­quency (SRF) cav­i­ties is trapped mag­netic flux. The flux trap­ping mech­a­nism de­pends on many fac­tors that in­clude cool-down con­di­tions, sur­face prepa­ra­tion tech­niques, and am­bi­ent mag­netic field ori­en­ta­tion. Suit­able di­ag­nos­tic tools are not yet avail­able to quan­ti­ta­tively cor­re­late such fac­tors’ ef­fect on the flux trap­ping mech­a­nism. A mag­netic field scan­ning sys­tem (MFSS) con­sist­ing of AMR sen­sors, flux­gate mag­ne­tome­ters, or Hall probes is re­cently com­mis­sioned to scan the local mag­netic field of trapped vor­tices around 1.3 GHz sin­gle-cell SRF cav­i­ties. In this con­tri­bu­tion, we will pre­sent re­sults from sen­si­tiv­ity cal­i­bra­tion and the first tests of AMR sen­sors in the MFSS. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB344  
About • paper received ※ 19 May 2021       paper accepted ※ 09 June 2021       issue date ※ 25 August 2021  
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TUPAB345 Availability Modeling of the Solid-State Power Amplifiers for the CERN SPS RF Upgrade operation, simulation, MMI, SRF 2308
 
  • L. Felsberger, A. Apollonio, T. Cartier-Michaud, E. Montesinos, J.C. Oliveira, J.A. Uythoven
    CERN, Geneva, Switzerland
  
  Funding: This project has received funding from the Euratom research and training programme 2019-2020 under grant agreement No 945077.
As part of the LHC In­jec­tor Up­grade pro­gram a com­plete over­haul of the Super Pro­ton Syn­chro­tron Ra­dio-Fre­quency (RF) sys­tem took place. New cav­i­ties have been in­stalled for which the solid-state tech­nol­ogy was cho­sen to de­liver a com­bined RF power of 2 MW from 2560 RF am­pli­fiers. This strat­egy promises high avail­abil­ity as the sys­tem con­tin­ues op­er­a­tion when some of the am­pli­fiers fail. This study quan­ti­fies the op­er­a­tional avail­abil­ity that can be achieved with this new in­stal­la­tion. The eval­u­a­tion is based on a Monte Carlo sim­u­la­tion of the sys­tem using the novel Avail­Sim4 sim­u­la­tion soft­ware. A model based on life­time es­ti­ma­tions of the RF mod­ules is com­pared against data from early op­er­a­tional ex­pe­ri­ence. Sen­si­tiv­ity analy­ses have been made, that give in­sight to the cho­sen op­er­a­tional sce­nario. With the in­creas­ing use of solid-state RF power am­pli­fiers, the find­ings of this study pro­vide a use­ful ref­er­ence for fu­ture ap­pli­ca­tion of this tech­nol­ogy in par­ti­cle ac­cel­er­a­tors. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB345  
About • paper received ※ 19 May 2021       paper accepted ※ 01 July 2021       issue date ※ 02 September 2021  
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TUPAB346 Development of a 500-MHz 150-kW Solid-State Power Amplifier for High Energy Photon Source GUI, controls, photon, booster 2312
 
  • Y.L. Luo, T.M. Huang, J. Li, H.Y. Lin, Q. Ma, Q.Y. Wang, P. Zhang, F.C. Zhao
    IHEP, Beijing, People’s Republic of China
  
  A 500-MHz 150-kW solid-state power am­pli­fier (SSA) has been de­vel­oped to test the 500-MHz nor­mal con­duct­ing cav­i­ties for High En­ergy Pho­ton Source (HEPS) booster ring. It will also be used to power nor­mal con­duct­ing cav­i­ties in the ini­tial beam com­mis­sion­ing stage of the HEPS stor­age ring. A total num­ber of 96 am­pli­fier mod­ules are com­bined ini­tially by coax­ial and later by wave­guide com­bin­ers to de­liver the 150-kW RF power. The final out­put is of EIA stan­dard WR1800 rec­tan­gu­lar wave­guide. Each am­pli­fier mod­ule con­sists four tran­sis­tors equipped with in­di­vid­ual cir­cu­la­tor and load and out­puts 2-kW RF power. Mod­u­lar­ity, re­dun­dancy and sat­is­fac­tory RF per­for­mance are demon­strated. In the final stage of HEPS pro­ject, this 150-kW am­pli­fier will be mod­i­fied to a 100-kW am­pli­fier to join the other five 100-kW SSAs for nor­mal op­er­a­tion of the booster cav­i­ties. The de­vel­op­ment and test re­sults are pre­sented in this paper.  
poster icon Poster TUPAB346 [1.870 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB346  
About • paper received ※ 19 May 2021       paper accepted ※ 21 June 2021       issue date ※ 12 August 2021  
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TUPAB347 Development of a 166-MHz 260-kW Solid-State Power Amplifier for High Energy Photon Source controls, photon, status, power-supply 2315
 
  • Y.L. Luo, T.M. Huang, J. Li, H.Y. Lin, Q. Ma, Q.Y. Wang, P. Zhang, F.C. Zhao
    IHEP, Beijing, People’s Republic of China
  
  166-MHz 260-kW solid-state power am­pli­fiers have been cho­sen to drive the 166.6-MHz su­per­con­duct­ing cav­i­ties for the stor­age ring of High En­ergy Pho­ton Source. Highly mod­u­lar yet com­pact are de­sired. A total num­ber of 112 am­pli­fier mod­ules of 3 kW each are com­bined in a multi-stage power com­bin­ing topol­ogy. The final out­put is of 9-3/16" 50 Ω coax­ial rigid line. Each am­pli­fier mod­ule con­sists of 3 LDMOS tran­sis­tors with in­di­vid­ual cir­cu­la­tor and load. Ther­mal sim­u­la­tions of the am­pli­fier mod­ule have been con­ducted to op­ti­mize cool­ing ca­pa­bil­i­ties for both trav­el­ling-wave and full-re­flec­tion op­er­a­tion sce­nar­ios. High ef­fi­ciency, suf­fi­cient re­dun­dancy and ex­cel­lent RF per­for­mances of the 260-kW sys­tem are demon­strated. A con­trol sys­tem is also in­te­grated and EPICS is used to man­age the mon­i­tored data. The de­sign and test re­sults of the am­pli­fier sys­tem are pre­sented in this paper.  
poster icon Poster TUPAB347 [1.972 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB347  
About • paper received ※ 19 May 2021       paper accepted ※ 21 June 2021       issue date ※ 19 August 2021  
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TUPAB348 Magnetron R&D for High Efficiency CW RF Sources for Industrial Accelerators injection, experiment, GUI, MMI 2318
 
  • H. Wang, K. Jordan, R.M. Nelson, R.A. Rimmer, S.O. Solomon
    JLab, Newport News, Virginia, USA
  • B.R.L. Coriton, C.P. Moeller, K.A. Thackston
    GA, San Diego, California, USA
  
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177, and DOE OS/HEP Accelerator Stewardship award 2019-2021.
The scheme of using high-ef­fi­ciency mag­netrons to drive ra­diofre­quency ac­cel­er­a­tors has been demon­strated at 2450 MHz in CW mode *. Mag­netron test stands at JLab and GA have been set up to fur­ther test the noise fig­ure and the lock­ing speed of the in­jec­tion phase-lock method. For higher power ap­pli­ca­tions, power com­bin­ing ex­per­i­ments using a TM010 cav­ity-type com­biner and a magic tee for the bi­nary com­biner while using a sin­gle clean in­jec­tion sig­nal has been car­ried out at 2450 MHz. The fre­quency pulling ef­fect be­tween the mag­netron and a low-Q cav­ity has been shown to en­hance the fre­quency lock­ing band­width com­pared to the in­jec­tion phase-lock alone. The prin­ci­ple has been stud­ied by the equiv­a­lent cir­cuit sim­u­la­tion, an­a­lyt­i­cal model, and fi­nally con­firmed ex­per­i­men­tally on the mag­netrons. Due to the pan­demic delay in 2020, the equiv­a­lent high power tests using a 75kW, 915MHz in­dus­trial mag­netron will be done in 2021 and will be re­ported in a fu­ture paper.
* H. Wang, et al, Magnetron R&Ds for High-Efficiency CW RF Sources of Particle Accelerators, WEXXPLS1, proceedings of IPAC 2019, Melbourne, Australia, May 19 -24, 2019. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB348  
About • paper received ※ 22 May 2021       paper accepted ※ 21 June 2021       issue date ※ 16 August 2021  
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TUPAB349 High Efficiency, Low Cost RF Sources for Accelerators and Colliders klystron, controls, simulation, electron 2322
 
  • R.L. Ives, T. Bui, G. Collins, H. Freund, T.W. Habermann, D. Marsden, M.E. Read
    CCR, San Mateo, California, USA
  • B.E. Chase, J. Reid
    Fermilab, Batavia, Illinois, USA
  • N. Chaudhary, J.R. Conant, T. Cox, R. Ho, C. McVey, C.M. Walker
    CPI, Palo Alto, California, USA
  • J.C. Frisch, L. Ma
    SLAC, Menlo Park, California, USA
  • A. Jensen
    Leidos Corp, Billerica, MA, USA
  • J.M. Potter
    JP Accelerator Works, Los Alamos, New Mexico, USA
  • W. Sessions
    Georgia Tech Research Institute, Smyrna, Georgia, USA
  
  Funding: U.S. Department of Energy
Cal­abazas Creek Re­search, Inc. (CCR) and its col­lab­o­ra­tors are de­vel­op­ing high ef­fi­ciency, low cost RF sources. Phase and Am­pli­tude Con­trolled Mag­netrons: CCR, Fer­mi­lab, and Com­mu­ni­ca­tions & Power In­dus­tries, LLC (CPI) re­cently de­vel­oped a 100 kW, 1.3 GHz mag­netron sys­tem with am­pli­tude and phase con­trol. The sys­tem op­er­ated at more than 80% ef­fi­ciency and demon­strated rapid con­trol of am­pli­tude and phase. Mul­ti­ple Beam Tri­odes: CCR, in col­lab­o­ra­tion with CPI and JP Ac­cel­er­a­tor Works, Inc., is de­vel­op­ing 200 kW, pulsed and CW RF sources from 350 to 700 MHz with pro­jected ef­fi­cien­cies ex­ceed­ing 80% and cost of $0.50/Watt. Pro­to­type tubes are sched­uled for tests in spring 2021. High Ef­fi­ciency Kly­strons:CCR, CPI, and Lei­dos, Inc. are build­ing a 1.3 GHz, 100 kW kly­stron op­er­at­ing at 80% ef­fi­ciency. High power test­ing is sched­uled for sum­mer 2021. Mul­ti­ple Beam IOTs: CCR and Geor­gia Tech Re­search In­sti­tute are de­vel­op­ing MBIOTs with sim­pli­fied input cou­pling and high ef­fi­ciency. Sim­u­la­tions in­di­cate that 3rd har­monic drive power can in­crease the ef­fi­ciency 8-10 %. The pro­gram is de­vel­op­ing a pro­to­type tube to pro­duce 200 kW peak, 100 kW av­er­age power at 704 MHz. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB349  
About • paper received ※ 18 May 2021       paper accepted ※ 01 June 2021       issue date ※ 24 August 2021  
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TUPAB354 352-MHz Solid State RF System Development at the Advanced Photon Source GUI, controls, PLC, klystron 2335
 
  • D. Horan, D.J. Bromberek, N.P. DiMonte, A. Goel, T.J. Madden, A. Nassiri, G. Trento, G.J. Waldschmidt
    ANL, Lemont, Illinois, USA
  
  De­vel­op­ment ef­fort is un­der­way on a 352MHz, 200kW solid state rf sys­tem in­tended as the base de­sign to re­place the ex­ist­ing kly­stron-based rf sys­tems presently in use at the Ad­vanced Pho­ton Source (APS). A six­teen-in­put, 200kW final com­bin­ing cav­ity was de­signed, built, and suc­cess­fully tested to 29kW CW in com­biner mode, and to 200kW CW in back-feed mode, where an ex­ter­nal kly­stron was used to trans­mit power into the com­bin­ing cav­ity. A four-port wave­guide com­biner was also tested in both back­feed and com­biner mode to 193kW and 26kW re­spec­tively. Slow and fast in­ter­lock sys­tems were de­signed and im­ple­mented to sup­port the test­ing process. An EPICS and Pro­gram­ma­ble Logic Con­troller (PLC)-based sys­tem was de­vel­oped to con­trol, com­mu­ni­cate with, and mon­i­tor the rf am­pli­fiers used in the com­biner-mode test, and to mon­i­tor and log sys­tem per­for­mance pa­ra­me­ters re­lat­ing to the com­bin­ing cav­ity. Low-level rf con­trol of the cav­ity in 29kW com­biner-mode op­er­a­tion was achieved using the ex­ist­ing APS ana­log low-level rf hard­ware. Test data and de­sign de­tails are pre­sented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB354  
About • paper received ※ 18 May 2021       paper accepted ※ 31 May 2021       issue date ※ 24 August 2021  
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TUPAB355 Design and Implementation of a Production Model Bias Tee multipactoring, high-voltage, MMI, linac 2339
 
  • T.L. Larter, E. Gutierrez, S.H. Kim, D.G. Morris, J.T. Popielarski, T. Xu, S. Zhao
    FRIB, East Lansing, Michigan, USA
  
  Funding: This work is supported by the US Department of Energy Office of Science under Cooperative Agreement DE-SC0000661, the State of Michigan and Michigan State University.
The Fa­cil­ity for Rare Iso­tope Beams (FRIB) in­cludes two types of half wave SC res­onators (HWR) op­er­at­ing at 322MHz. The fun­da­men­tal power cou­plers used to trans­mit RF power into the HWRs com­monly suf­fer from mul­ti­pact­ing which can re­sult in long con­di­tion­ing times. A bias tee can be used to apply a high volt­age to the cou­plers to help al­le­vi­ate mul­ti­pact­ing. A pro­duc­tion ver­sion of the bias tee was com­mis­sioned for use at FRIB. The bias tee went through sev­eral de­sign re­vi­sions to di­ag­nose and cor­rect ther­mal dis­si­pa­tion is­sues. This paper will dis­cuss de­tails of de­sign and chal­lenges faced dur­ing pro­duc­tion val­i­da­tion of the bias tee. 		 
poster icon Poster TUPAB355 [0.630 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB355  
About • paper received ※ 19 May 2021       paper accepted ※ 28 May 2021       issue date ※ 14 August 2021  
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TUPAB356 Electron Beam Driven Cavities electron, simulation, linac, klystron 2342
 
  • M. Schuett, U. Ratzinger
    IAP, Frankfurt am Main, Germany
  
  State of the art high power feeder for RF cav­i­ties used as ac­cel­er­a­tors gen­er­ally re­quire RF am­pli­fiers con­sist­ing of a vac­uum tube, such as a kly­stron or Grid Tubes. In ad­di­tion, a num­ber of cost in­ten­sive RF aux­il­iary de­vices are needed: Mod­u­la­tor, wave­guides, cir­cu­la­tor, power dump and cou­plers. The equip­ment re­quires sig­nif­i­cant floor space within the linac build­ing. Al­ter­na­tively, we pro­pose a di­rect dri­ven sys­tem. Aμbunched elec­tron beam is in­jected di­rectly into the cav­ity. A high per­veance bunched elec­tron beam can be gen­er­ated by a stan­dard elec­tron gun com­bined with a de­flect­ing beam chop­per*, an off-the-shelf IOT or kly­stron, re­spec­tively. The pulse rate is de­ter­mined by the res­o­nance fre­quency of the cav­ity. The res­onator hereby acts like the out­put cav­ity of a kly­stron: Within its prop­a­ga­tion through the cav­ity the beam is de­cel­er­ated in­creas­ing the stored en­ergy of the ac­cel­er­a­tor. We pre­sent 3D par­ti­cle PIC sim­u­la­tions eval­u­at­ing the geom­e­try and beam prop­er­ties in order to op­ti­mize the cou­pling ef­fi­ciency and cav­ity ex­ci­ta­tion of state-of-art CH par­ti­cle ac­cel­er­a­tor struc­tures.
* S. Setzer, T. Weiland and U. Ratzinger, A Chopped Electron Beam Driver for H-Type Cavities, 20th ‘International Linac Conference, Monterey, California, August 21-25, 2000, pp. 1001-1003 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB356  
About • paper received ※ 19 May 2021       paper accepted ※ 21 June 2021       issue date ※ 21 August 2021  
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TUPAB358 Novel 500 MHz Solid State Power Amplifier Module Development at Sirius operation, impedance, synchrotron, storage-ring 2349
 
  • M.H. Wallner, R.H. Farias, A.P.B. Lima, F. Santiago de Oliveira
    LNLS, Campinas, Brazil
  
  A new solid state power am­pli­fier (SSPA) mod­ule is being de­vel­oped at the Brazil­ian Cen­ter for Re­search in En­ergy and Ma­te­ri­als (CNPEM) to drive one of the su­per­con­duct­ing RF cav­i­ties to be in­stalled at Sir­ius, its new 3 GeV fourth gen­er­a­tion syn­chro­tron light source. Sev­eral pro­to­types have been built and tested in-house, and a pla­nar balun was de­signed to achieve a push-pull con­fig­u­ra­tion at deep class AB op­er­a­tion. Ef­forts to op­ti­mize heat ex­change in var­i­ous ways have been made. Re­sults ob­tained thus far are pre­sented and the next steps con­cern­ing de­vel­op­ment are dis­cussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB358  
About • paper received ※ 19 May 2021       paper accepted ※ 18 June 2021       issue date ※ 18 August 2021  
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TUPAB395 Vacuum System Models for Minerva Linac Design vacuum, linac, rfq, MEBT 2443
 
  • S. Rey, M.A. Baylac, F. Bouly, E. Froidefond
    LPSC, Grenoble Cedex, France
  • F. Davin, D. Vandeplassche
    SCK•CEN, Mol, Belgium
  • L. Perrot, H. Saugnac
    Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
  
  The goal of the MYRRHA pro­ject is to demon­strate the tech­ni­cal fea­si­bil­ity of trans­mu­ta­tion in a 100 MW Ac­cel­er­a­tor Dri­ven Sys­tem (ADS) by build­ing a new flex­i­ble ir­ra­di­a­tion com­plex at Mol (Bel­gium). The MYRRHA fa­cil­ity re­quires a 600 MeV ac­cel­er­a­tor de­liv­er­ing a max­i­mum pro­ton cur­rent of 4 mA in con­tin­u­ous wave op­er­a­tion, with an ad­di­tional re­quire­ment for ex­cep­tional re­li­a­bil­ity. Sup­ported by SCK•CEN and the Bel­gian fed­eral gov­ern­ment the pro­ject has en­tered in its phase I: this in­cludes the de­vel­op­ment and the con­struc­tion of the linac first part, up to 100 MeV. We here re­view the MIN­ERVA linac vac­uum sys­tem mod­el­ling stud­ies that en­abled to val­i­date the choice of ma­te­ri­als and vac­uum equip­ment. The strengths and weak­nesses of the vac­uum de­sign, high­lighted by the mod­els, will be dis­cussed as well as the re­quired im­prove­ments.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB395  
About • paper received ※ 19 May 2021       paper accepted ※ 01 June 2021       issue date ※ 12 August 2021  
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TUPAB399 RF Characterisation of New Coatings for Future Circular Collider Beam Screens impedance, laser, collider, electron 2453
 
  • P. Krkotić, F. Pérez, M. Pont, N.D. Tagdulang
    ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
  • S. Calatroni
    CERN, Meyrin, Switzerland
  • X. Granados, J. Gutierrez, T. Puig, A. Romanov, G.T. Telles
    ICMAB, Bellatera, Spain
  • A.N. Hannah, O.B. Malyshev, R. Valizadeh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • J.M. O’Callaghan Castella
    Universitat Politécnica de Catalunya, Barcelona, Spain
  • D. Whitehead
    The University of Manchester, Laser Processing Research Center, Manchester, United Kingdom
  
  For the fu­ture high en­ergy col­lid­ers being under the de­sign at this mo­ment, the choice of a low sur­face im­ped­ance beam screen coat­ing ma­te­r­ial has be­come of fun­da­men­tal im­por­tance to en­sure suf­fi­ciently low beam im­ped­ance and con­se­quently guar­an­teed sta­ble op­er­a­tion at high cur­rents. We have stud­ied the use of high-tem­per­a­ture su­per­con­duct­ing coated con­duc­tors as pos­si­ble coat­ing ma­te­ri­als for the beam screen of the FCC-hh. In ad­di­tion, amor­phous car­bon coat­ing and laser-based sur­face treat­ment tech­niques are ef­fec­tive sur­face treat­ments to lower the sec­ondary elec­tron yield and min­imise the elec­tron cloud build-up. We have de­vel­oped and adapted dif­fer­ent ex­per­i­men­tal se­tups based on res­onat­ing struc­tures at fre­quen­cies below 10 GHz to study the re­sponse of these coat­ings and their mod­i­fied sur­faces under the in­flu­ence of RF fields and DC mag­netic fields up to 9 T. Tak­ing the FCC-hh as a ref­er­ence, we will show that the sur­face re­sis­tance for RE­BCO-CCs is much lower than that of Cu. Fur­ther we show that the ad­di­tional sur­face mod­i­fi­ca­tions can be op­ti­mised to min­imise their im­pact on the sur­face im­ped­ance. Re­sults from se­lected coat­ings will be pre­sented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB399  
About • paper received ※ 19 May 2021       paper accepted ※ 25 June 2021       issue date ※ 16 August 2021  
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TUPAB417 Pushing Spatial Resolution Limits In Single-Shot Time-Resolved Transmission Electron Microscopy at the UCLA Pegasus Laboratory electron, space-charge, gun, simulation 2506
 
  • P.E. Denham, P. Musumeci
    UCLA, Los Angeles, USA
  
  Funding: This work was supported by DOESTTR grant No. DE-SC0013115 and by by the National Science Foundation under STROBE Science and Technology Center Grant No. DMR-1548924
We pre­sent the de­sign of a high-speed sin­gle shot rel­a­tivis­tic elec­tron mi­cro­scope planned for im­ple­men­ta­tion at the UCLA PE­GA­SUS Lab­o­ra­tory ca­pa­ble of imag­ing with less than 30~nm spa­tial res­o­lu­tion and image ac­qui­si­tion time on the order of 10~ps. This work is based on a multi-cav­ity ac­cel­er­a­tion scheme for pro­duc­ing rel­a­tivis­tic beams (3.75 MeV) with sup­pressed rms en­ergy spread (σδ ≈5e-5), and a means to re­duce smooth space charge aber­ra­tions by gen­er­at­ing a quasi-op­ti­mal 4D par­ti­cle dis­tri­b­u­tion at the sam­ple plane. start-to-end sim­u­la­tion re­sults are used to val­i­date the en­tire setup. Ul­ti­mately, a fea­si­ble work­ing point is demon­strated. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB417  
About • paper received ※ 19 May 2021       paper accepted ※ 28 July 2021       issue date ※ 12 August 2021  
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WEXA01 Successful Crabbing of Proton Beams luminosity, collider, emittance, impedance 2510
 
  • R. Calaga
    CERN, Meyrin, Switzerland
  
  Funding: Research supported by the HL-LHC project and by the DOE and UK-STFC.
Many fu­ture par­ti­cle col­lid­ers re­quire beam crab­bing to re­cover the geo­met­ric lu­mi­nos­ity loss from the non-zero cross­ing angle at the in­ter­ac­tion point. A first demon­stra­tion ex­per­i­ment of crab­bing with hadron beams was suc­cess­fully car­ried out with high en­ergy pro­tons. This break­through re­sult is fun­da­men­tal to achieve the physics goals of the high lu­mi­nos­ity LHC up­grade pro­ject (HL-LHC) and the fu­ture cir­cu­lar col­lider (FCC). The ex­pected peak lu­mi­nos­ity gain (re­lated to col­li­sion rate) is 65% for HL-LHC, and even greater for the FCC. Novel beam physics ex­per­i­ments with pro­ton beams in CERN’s Super Pro­ton Syn­chro­tron (SPS) were per­formed to demon­strate sev­eral crit­i­cal as­pects for the op­er­a­tion of crab cav­i­ties in the fu­ture HL-LHC in­clud­ing trans­parency with a pair of cav­i­ties, a full char­ac­ter­i­za­tion of the cav­ity im­ped­ance with high beam cur­rents and con­trolled emit­tance growth from crab cav­ity in­duced RF noise. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEXA01  
About • paper received ※ 14 May 2021       paper accepted ※ 28 July 2021       issue date ※ 15 August 2021  
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WEXA02 Operational Electron Cooling in the Relativistic Heavy Ion Collider electron, operation, collider, cathode 2516
 
  • A.V. Fedotov, K.A. Drees, W. Fischer, X. Gu, D. Kayran, J. Kewisch, C. Liu, K. Mernick, M.G. Minty, V. Schoefer, H. Zhao
    BNL, Upton, New York, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
Since the in­ven­tion of the elec­tron cool­ing tech­nique its ap­pli­ca­tion to cool hadron beams in col­lid­ers was con­sid­ered for nu­mer­ous ac­cel­er­a­tor physics pro­jects world­wide. How­ever, achiev­ing the re­quired high-bright­ness elec­tron beams of re­quired qual­ity and cool­ing of ion beams in col­li­sions was deemed to be chal­leng­ing. An elec­tron cool­ing of ion beams em­ploy­ing a high-en­ergy ap­proach with RF-ac­cel­er­ated elec­tron bunches was re­cently suc­cess­fully im­ple­mented at BNL. It was used to cool ion beams in both col­lider rings with ion beams in col­li­sion. Elec­tron cool­ing in RHIC be­came fully op­er­a­tional dur­ing the 2020 physics run and led to sub­stan­tial im­prove­ments in lu­mi­nos­ity. This pre­sen­ta­tion will dis­cuss im­ple­men­ta­tion, op­ti­miza­tion and chal­lenges of elec­tron cool­ing for col­lid­ing ion beams in RHIC. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEXA02  
About • paper received ※ 18 May 2021       paper accepted ※ 15 June 2021       issue date ※ 13 August 2021  
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WEXB01 The ESS Elliptical Cavity Cryomodules Production at CEA cryomodule, status, site, vacuum 2536
 
  • C. Madec
    CEA, Gif-sur-Yvette, France
  • C. Arcambal, S. Berry, A. Bouygues, G. Devanz, C. Mayri, P. Sahuquet, T. Trublet
    CEA-DRF-IRFU, France
  • P. Bosland, E. Cenni, C. Cloué, T. Hamelin, O. Piquet
    CEA-IRFU, Gif-sur-Yvette, France
  • P. Pierini
    ESS, Lund, Sweden
  
  CEA in Kind con­tri­bu­tion to the ESS su­per­con­duct­ing LINAC in­cludes 30 el­lip­ti­cal medium and high-beta cry­omod­ules. CEA is in charge of the pro­duc­tion of all the com­po­nents (ex­cept the cav­i­ties de­liv­ered by LASA and STFC) as well as the as­sem­bly of the cry­omod­ules and a few cryo­genic and RF tests. The power cou­plers op­er­at­ing at a max­i­mum power of 1.1MW on a 3.6ms pulse at 14Hz are con­di­tioned at high RF power on a ded­i­cated stand. The as­sem­bly of the cry­omod­ules is per­formed at CEA by a pri­vate Com­pany under the su­per­vi­sion of CEA. This paper pre­sents the sta­tus of the cry­omod­ules pro­duc­tion and the in­fra­struc­ture ded­i­cated to this pro­ject at CEA Saclay.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEXB01  
About • paper received ※ 18 May 2021       paper accepted ※ 19 July 2021       issue date ※ 21 August 2021  
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WEXB06 Development of an APF IH-DTL in the J-PARC Muon g-2/EDM Experiment DTL, linac, experiment, focusing 2544
 
  • Y. Nakazawa, H. Iinuma
    Ibaraki University, Hitachi, Ibaraki, Japan
  • E. Cicek, N. Kawamura, T. Mibe, M. Yoshida
    KEK, Ibaraki, Japan
  • N. Hayashizaki
    RLNR, Tokyo, Japan
  • Y. Iwata
    NIRS, Chiba-shi, Japan
  • R. Kitamura, Y. Kondo, T. Morishita
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  • M. Otani, N. Saito
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  • Y. Sue, K. Sumi, M. Yotsuzuka
    Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan
  • Y. Takeuchi
    Kyushu University, Fukuoka, Japan
  • T. Yamazaki
    KEK, Tokai Branch, Tokai, Naka, Ibaraki, Japan
  • H.Y. Yasuda
    University of Tokyo, Tokyo, Japan
  
  An in­ter-dig­i­tal H-mode drift-tube linac (IH-DTL) is under de­vel­op­ment in a muon linac at the J-PARC muon g-2/EDM ex­per­i­ment. It ac­cel­er­ates muons from 0.34 MeV to 4.3 MeV at an op­er­at­ing fre­quency of 324 MHz. The cav­ity can be minia­tur­ized by in­tro­duc­ing the al­ter­na­tive phase fo­cus­ing (APF) method that en­ables trans­verse fo­cus­ing only with an E-field. The APF IH-DTL cav­ity was mod­eled by a three-di­men­sional field analy­sis, and the beam dy­nam­ics were eval­u­ated nu­mer­i­cally. The beam emit­tance was cal­cu­lated as 0.316pi and 0.189pi mm mrad in the hor­i­zon­tal and ver­ti­cal di­rec­tions, re­spec­tively. It sat­is­fies the ex­per­i­men­tal re­quire­ment. Ac­tu­ally, the field error due to the fab­ri­ca­tion er­rors and ther­mal ex­pan­sion dur­ing op­er­a­tion causes an emit­tance growth. It was eval­u­ated that the op­ti­mized tuners can sup­press the emit­tance growth to less than 10%. In this paper, the de­tailed de­sign of the APF IH-DTL in­clud­ing the tuner will be re­ported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEXB06  
About • paper received ※ 19 May 2021       paper accepted ※ 29 July 2021       issue date ※ 20 August 2021  
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WEXC03 Review of Superconducting Radio Frequency Gun cathode, gun, SRF, operation 2556
 
  • R. Xiang
    HZDR, Dresden, Germany
  
  The suc­cess of pro­posed high power free-elec­tron lasers (FELs) and en­ergy re­cov­ery linac (ERL) largely de­pends on the de­vel­op­ment of the elec­tron source, which re­quires the best beam qual­ity and CW op­er­a­tion. An el­e­gant way to re­al­ize this av­er­age bril­liance is to com­bine the high beam qual­ity of ma­ture nor­mal con­duct­ing radio fre­quency pho­toin­jec­tor with the quick de­vel­op­ing su­per­con­duct­ing radio fre­quency tech­nol­ogy, to build su­per­con­duct­ing rf pho­toin­jec­tors (SRF guns). In last decade, sev­eral SRF gun pro­grams based on dif­fer­ent ap­proaches have achieved promis­ing progress, even suc­ceeded in rou­tine op­er­a­tion at BNL and HZDR [*,**]. In the near fu­ture SRF guns are ex­pected to play an im­por­tant role for hard X-ray FEL fa­cil­i­ties. In this con­tri­bu­tion, we will re­view the de­sign con­cepts, pa­ra­me­ters, and the sta­tus of the major SRF gun pro­jects.
*I. Petrushina et al., Phys. Rev. Lett. 124, 244801
**J. Teichert at al., Phys. Rev. Accel. Beams 24, 033401
 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEXC03  
About • paper received ※ 19 May 2021       paper accepted ※ 28 June 2021       issue date ※ 11 August 2021  
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WEPAB006 EIC Crab Cavity Multipole Analysis multipole, dynamic-aperture, collider, simulation 2589
 
  • Q. Wu, Y. Luo, B.P. Xiao
    BNL, Upton, New York, USA
  • S.U. De Silva
    ODU, Norfolk, Virginia, USA
  • J.A. Mitchell
    CERN, Geneva, Switzerland
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
Crab cav­i­ties are spe­cial­ized RF de­vices de­signed for col­lid­ers tar­get­ing high lu­mi­nosi­ties. It is a straight­for­ward so­lu­tion to re­trieve head-on col­li­sion with cross­ing angle ex­ist­ing to fast sep­a­rate both beams after col­li­sion. The Elec­tron Ion Col­lider (EIC) has a cross­ing angle of 25 mrad, and will use local crab­bing to min­i­mize the dy­namic aper­ture re­quire­ment through­out the rings. The cur­rent crab cav­ity de­sign for the EIC lacks axial sym­me­try. There­fore, their higher order com­po­nents of the fun­da­men­tal de­flect­ing mode have a po­ten­tial of af­fect­ing the long-term beam sta­bil­ity. We pre­sent here the mul­ti­pole analy­sis and pre­lim­i­nary par­ti­cle track­ing re­sults from the cur­rent crab cav­ity de­sign. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB006  
About • paper received ※ 18 May 2021       paper accepted ※ 25 June 2021       issue date ※ 12 August 2021  
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WEPAB009 Study of Harmonic Crab Cavity in EIC Beam-Beam Simulations simulation, resonance, betatron, electron 2595
 
  • D. Xu, Y. Hao
    FRIB, East Lansing, Michigan, USA
  • Y. Luo, C. Montag
    BNL, Upton, New York, USA
  • J. Qiang
    LBNL, Berkeley, California, USA
  
  In the Elec­tron-Ion Col­lider (EIC) de­sign, crab cav­i­ties are adopted to com­pen­sate the geo­met­ric lu­mi­nos­ity loss from the cross­ing angle. From pre­vi­ous stud­ies, higher-or­der syn­chro-be­ta­tron res­o­nances are ex­cited since the hadron beam is long and the cross­ing angle is large. To re­duce the lu­mi­nos­ity degra­da­tion rate, dif­fer­ent com­bi­na­tions of har­monic crab cav­i­ties are stud­ied with both weak-strong and strong-strong sim­u­la­tion meth­ods. The fre­quency map analy­sis (FMA) is also used for com­par­i­son. This study helps de­ter­mine the crab cav­ity pa­ra­me­ters for the fu­ture EIC.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB009  
About • paper received ※ 17 May 2021       paper accepted ※ 23 June 2021       issue date ※ 30 August 2021  
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WEPAB010 Full Range Tune Scan Studies Using Graphics Processing Units with CUDA in EIC Beam-Beam Simulations simulation, resonance, betatron, GPU 2598
 
  • D. Xu, Y. Hao
    FRIB, East Lansing, Michigan, USA
  • Y. Luo, C. Montag
    BNL, Upton, New York, USA
  • J. Qiang
    LBNL, Berkeley, California, USA
  
  The hadron beam in the Elec­tron-Ion Col­lider (EIC) suf­fers high order be­ta­tron and syn­chro-be­ta­tron res­o­nances. In this paper, we pre­sent a weak-strong full range (0.0~0.5) frac­tional tune scan with a step size as small as 0.001. Mul­ti­ple Graph­ics Pro­cess­ing Units (GPUs) are used to speed up the sim­u­la­tion. A code par­al­lelized with MPI and CUDA is im­ple­mented. The good tune re­gion from weak-strong scan is fur­ther checked by the self-con­sis­tent strong-strong sim­u­la­tion. This study pro­vides beam dy­nam­ics guid­ance in choos­ing proper work­ing points for the fu­ture EIC.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB010  
About • paper received ※ 17 May 2021       paper accepted ※ 23 June 2021       issue date ※ 23 August 2021  
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WEPAB019 RF Harmonic Kicker R&D Demonstration and Its Application to the RCS Injection of the EIC kicker, injection, electron, operation 2632
 
  • G.-T. Park, M.W. Bruker, J.M. Grames, J. Guo, R.A. Rimmer, S.O. Solomon, H. Wang
    JLab, Newport News, Virginia, USA
  
  The Rapid Cy­cling Syn­chro­tron (RCS) of the Elec­tron-Ion Col­lider (EIC) at Brookhaven Na­tional Lab­o­ra­tory (BNL) * is an ac­cel­er­at­ing com­po­nent of the elec­tron in­jec­tion com­plex, which pro­vides po­lar­ized elec­trons in elec­tron-ion col­li­sions in the main Elec­tron Stor­age Ring (ESR). We pre­sent the in­jec­tion scheme into the RCS based on an ul­tra-fast har­monic kicker, whose "five odd-har­monic modes" pro­to­type was de­vel­oped in the con­text of the Jef­fer­son Lab EIC (JLEIC) con­cep­tual de­sign **. In its early stage of R&D, the sharp (~3 ns width) wave­form con­struc­tion, beam dy­nam­ics, and pulsed power op­er­a­tion with short ramp­ing time (~10 us) will be dis­cussed to­gether with the fab­ri­ca­tion work of the JLEIC pro­to­type ***.
* BNL, "Electron Ion Collider Conceptual Design Report", 2020
** G. Park et. al, JLAB-TN-044
*** G. Park et. al., JLAB-TN-046 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB019  
About • paper received ※ 17 May 2021       paper accepted ※ 22 June 2021       issue date ※ 27 August 2021  
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WEPAB020 The Relation Between Field Flatness and the Passband Frequency in the Elliptical Cavities SRF, simulation, gun, accelerating-gradient 2636
 
  • G.-T. Park, R.A. Rimmer, H. Wang
    JLab, Newport News, Virginia, USA
  
  A tech­nique that pre­dicts the field flat­ness of the op­er­at­ing pi-mode based on the pass­band fre­quency is highly de­sir­able when the di­rect mea­sure­ment of the field is not avail­able. Such a tech­nique was de­vel­oped for the SNS-PPU cav­ity, a 6-cell SRF cav­ity whose field flat­ness is im­por­tant for cold op­er­a­tion. In this paper, we will pre­sent the the­ory on the re­la­tions be­tween field pro­file and pass­band fre­quen­cies of the ar­bi­trary de­formed cav­i­ties, the sim­u­la­tion stud­ies, and com­par­i­son with the ex­per­i­men­tal mea­sure­ments.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB020  
About • paper received ※ 17 May 2021       paper accepted ※ 24 June 2021       issue date ※ 31 August 2021  
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WEPAB038 Commissioning of a New X-Band, Low-Noise LLRF System klystron, LLRF, MMI, linac 2683
 
  • A.V. Edwards, M. Boronat Arevalo, N. Catalán Lasheras, G. McMonagle
    CERN, Meyrin, Switzerland
  • A.C. Dexter
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  
  To in­crease beam en­ergy in the CLEAR fa­cil­ity at CERN and study the CLIC ac­cel­er­at­ing struc­ture pro­to­type in op­er­at­ing con­di­tions, the first X-band test fa­cil­ity at CERN was up­graded in 2020. Both, the ac­qui­si­tion and soft­ware sys­tems at X-band test stand 1 (Xbox1) were up­graded to ex­hibit low phase noise which is rel­e­vant to kly­stron based CLIC and to the use of crab cav­i­ties in the beam de­liv­ery sys­tem. The new LLRF uses down-con­ver­sion which ne­ces­si­tates a local os­cil­la­tor which can be pro­duced by two dif­fer­ent meth­ods. The first is a PLL, a com­monly used tech­nique which has been pre­vi­ously em­ployed at the other X-band fa­cil­i­ties at CERN. The sec­ond is a novel ap­pli­ca­tion of a sin­gle side­band up-con­ver­tor. The up-con­ver­tor sys­tem has demon­strated re­duced phase noise when com­pared with the PLL. The com­mis­sion­ing of the new sys­tem began in late 2020 with the con­di­tion­ing of a 50 MW Kly­stron. Mea­sure­ments of the qual­ity of the new LLRF will be shown. These will com­pare the PLL and up-con­ver­tor with par­tic­u­lar at­ten­tion on the qual­ity of the phase mea­sure­ments. Also, a pre­lim­i­nary study of phase shifts in the wave­guide net­work due to tem­per­a­ture changes will be pre­sented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB038  
About • paper received ※ 13 May 2021       paper accepted ※ 05 July 2021       issue date ※ 23 August 2021  
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WEPAB041 Testing of the Milliampere Booster Prototype Cavity linac, vacuum, operation, solenoid 2693
 
  • R.G. Heine
    KPH, Mainz, Germany
  
  The Mil­liampere Booster (MAMBO) is the in­jec­tor linac for the Mainz En­ergy-re­cov­er­ing Su­per­con­duct­ing Ac­cel­er­a­tor MESA. MESA is a multi-turn en­ergy re­cov­ery linac with beam en­er­gies in the 100 MeV regime cur­rently de­signed and built at In­sti­tut für Kern­physik (KPH) of Jo­hannes Guten­berg-Uni­ver­sität Mainz. The main ac­cel­er­a­tor con­sists of two su­per­con­duct­ing Rossendorf type mod­ules, while the in­jec­tor MAMBO re­lies on nor­mal con­duct­ing tech­nolgy. The MAMBO RF cav­i­ties are bi-pe­ri­odic pi/2 struc­tures with 33 cells and 37 cells, re­spec­tively. In this paper we pre­sent the re­sults of the com­mis­sion­ing and test­ing of a 13 cell pro­to­type struc­ture.  
poster icon Poster WEPAB041 [2.824 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB041  
About • paper received ※ 18 May 2021       paper accepted ※ 23 June 2021       issue date ※ 23 August 2021  
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WEPAB048 Design of an Optical Cavity for Generating Intense THz Pulse Based on Coherent Cherenkov Radiation electron, radiation, gun, experiment 2711
 
  • P. Wang, Y. Koshiba, T. Murakami, K. Murakoshi, K. Sakaue, Y. Tadenuma, M. Washio
    Waseda University, Tokyo, Japan
  • R. Kuroda
    AIST, Tsukuba, Japan
  • K. Sakaue
    The University of Tokyo, Graduate School of Engineering, Bunkyo, Japan
  
  We have been study­ing ter­a­hertz (THz) gen­er­a­tion via Cherenkov ra­di­a­tion with high-qual­ity elec­tron beams from a pho­to­cath­ode rf (radio fre­quency) gun. In our early stud­ies, we have suc­ceeded in the gen­er­a­tion of co­her­ent Cherenkov ra­di­a­tion by con­trol­ling the tilt of the elec­tron beam using an rf-de­flec­tor. For fur­ther en­hance­ment, we are plan­ning to stack the THz pulses in an op­ti­cal cav­ity. Multi-bunch op­er­a­tion of the rf-gun will gen­er­ate elec­tron beams with a rep­e­ti­tion rate of 119 MHz, and THz pulses as well. These pulses will be ac­cu­mu­lated in the cav­ity for up to 150 pulses. In this con­fer­ence, we re­port the de­sign study of the en­hance­ment cav­ity and dis­cuss the per­for­mance of the THz source.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB048  
About • paper received ※ 19 May 2021       paper accepted ※ 02 June 2021       issue date ※ 22 August 2021  
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WEPAB065 Studies of the Energy Recovery Performance of the PERLE Project linac, HOM, electron, radiation 2744
 
  • K.D.J. André, B.J. Holzer
    CERN, Geneva, Switzerland
  • S.A. Bogacz
    JLab, Newport News, Virginia, USA
  
  The Pow­er­ful En­ergy Re­cov­ery Linac for Ex­per­i­ments (PERLE) is an ac­cel­er­a­tor fa­cil­ity for the de­vel­op­ment and ap­pli­ca­tion of the en­ergy re­cov­ery tech­nique for an in­tense 500 MeV elec­tron beam. The paper pre­sents the stud­ies that have been per­formed to as­sess the qual­ity of the ERL lat­tice de­sign and beam op­tics. The stud­ies in­clude the Co­her­ent Syn­chro­tron Ra­di­a­tion (CSR) emis­sion and wake­fields in the su­per­con­duct­ing ra­dio-fre­quency struc­tures of the linacs. The lat­tice de­sign and op­tics prin­ci­ples of the ERL struc­ture are dis­cussed, in­volv­ing the ver­ti­cal de­flec­tion sys­tem and the 180° arcs. Fi­nally, the re­sults of the front-to-end track­ing sim­u­la­tions that con­sider the com­plete multi-turn en­ergy re­cov­ery process are pre­sented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB065  
About • paper received ※ 18 May 2021       paper accepted ※ 24 June 2021       issue date ※ 14 August 2021  
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WEPAB079 Optics Studies on the Operation of a New Wiggler and Bunch Shortening at the DELTA Storage Ring wiggler, optics, storage-ring, operation 2772
 
  • B. Büsing, P. Hartmann, A. Held, S. Khan, C. Mai, D. Schirmer, G. Schmidt
    DELTA, Dortmund, Germany
  
  Funding: Work supported by Deutsche Forschungsgemeinschaft via project INST 212/330-1 AOBJ: 619186
The 1.5-GeV elec­tron stor­age ring DELTA is a syn­chro­tron light source op­er­ated by the TU Dort­mund Uni­ver­sity. Ra­di­a­tion from hard X-rays to the THz regime is pro­vided by di­pole mag­nets and in­ser­tion de­vices like un­du­la­tors and wig­glers. To pro­vide even shorter wave­lengths, a new 22-pole su­per­con­duct­ing 7-T wig­gler has been in­stalled. The edge fo­cus­ing of the wig­gler has a large im­pact on the lin­ear op­tics of the stor­age ring. Mea­sure­ments re­gard­ing its in­flu­ence and sim­u­la­tions were per­formed. In ad­di­tion, a sec­ond ra­diofre­quency (RF) cav­ity has been in­stalled to com­pen­sate the in­creased en­ergy loss per turn due to the new wig­gler. As a con­se­quence of the higher RF power, the elec­tron bunches are shorter com­pared to the old setup with only one cav­ity. In view of re­duc­ing the bunch length even more, stud­ies of the stor­age ring op­tics with re­duced mo­men­tum com­paction fac­tor were per­formed. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB079  
About • paper received ※ 19 May 2021       paper accepted ※ 24 June 2021       issue date ※ 22 August 2021  
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WEPAB081 The Broad-Band Impedance Budget in the Storage Ring of the ALS-U Project impedance, vacuum, wakefield, storage-ring 2779
 
  • D. Wang, K.L.F. Bane, R. Bereguer, T. Cui, S. De Santis, P. Gach, D. Li, T.H. Luo, T. Miller, T. Oliver, O. Omolayo, C. Steier, T.L. Swain, M. Venturini, G. Wang
    LBNL, Berkeley, California, USA
  
  De­sign work is un­der­way for the up­grade of the Ad­vanced Light Source (ALS-U) to a dif­frac­tion-lim­ited soft x-rays ra­di­a­tion source. Like other 4th-gen­er­a­tion light source ma­chines, the ALS-U mul­ti­ple-bend achro­mat stor­age-ring (SR) is po­ten­tially sen­si­tive to beam-cou­pling im­ped­ance ef­fects. This paper pre­sents the SR broad-band im­ped­ance bud­get in both the lon­gi­tu­di­nal and trans­verse planes. In our mod­el­ing we fol­low the com­monly ac­cepted ap­proach of sep­a­rat­ing the re­sis­tive-wall and the geo­met­ric parts of the im­ped­ance, the for­mer being de­scribed by an­a­lyt­i­cal for­mu­las and the lat­ter ob­tained by nu­mer­i­cal elec­tro­mag­netic codes (pri­mar­ily CST Stu­dio soft­ware) as­sum­ing per­fectly con­duct­ing ma­te­ri­als. We dis­cuss the main sources of im­ped­ance. Re­sults of our analy­sis are the basis for the sin­gle bunch in­sta­bil­ity study and would feed­back on the de­sign of crit­i­cal vac­uum com­po­nents.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB081  
About • paper received ※ 20 May 2021       paper accepted ※ 01 July 2021       issue date ※ 14 August 2021  
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WEPAB082 Single Bunch Instability Simulations in the Storage Ring of the ALS-U Project impedance, simulation, storage-ring, operation 2783
 
  • D. Wang, K.L.F. Bane, S. De Santis, M.P. Ehrlichman, D. Li, T.H. Luo, O. Omolayo, G. Penn, C. Steier, M. Venturini
    LBNL, Berkeley, California, USA
  
  As the broad-band im­ped­ance mod­el­ing and the vac­uum cham­ber de­sign of the new Ad­vanced Light Source stor­age ring (ALS- U) reach ma­tu­rity, we re­port on progress in sin­gle-bunch col­lec­tive ef­fects stud­ies. A pseudo-Green func­tion wake rep­re­sent­ing the en­tire ring was ear­lier ob­tained by nu­mer­i­cal and an­a­lyt­i­cal meth­ods. Macropar­ti­cle sim­u­la­tions using the com­puter code "el­e­gant" and this wake func­tion are used to de­ter­mine the in­sta­bil­ity thresh­olds for lon­gi­tu­di­nal and trans­verse mo­tion. We con­sider var­i­ous op­er­at­ing con­di­tions, such as with­out/with higher-har­monic RF cav­i­ties, zero/fi­nite lin­ear chro­matic­ity, and with­out/with a trans­verse bunch-by-bunch feed­back sys­tem. Re­sults show enough mar­gin for the broad­band im­ped­ance bud­get when the sin­gle-bunch in­sta­bil­ity thresh­olds are com­pared with the de­sign bunch charge.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB082  
About • paper received ※ 20 May 2021       paper accepted ※ 01 July 2021       issue date ※ 18 August 2021  
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WEPAB090 Higher Order Mode Damping for 166 MHz and 500 MHz Superconducting RF Cavities at High Energy Photon Source HOM, impedance, damping, storage-ring 2798
 
  • H.J. Zheng, Z.Q. Li, F. Meng, N. Wang, H.S. Xu, P. Zhang, X.Y. Zhang
    IHEP, Beijing, People’s Republic of China
  
  Funding: This work was supported in part by High Energy Photon Source, in part by the National Natural Science Foundation of China under Grant No. 11905232.
Su­per­con­duct­ing rf cav­i­ties have been cho­sen for High En­ergy Pho­ton Source, a 6 GeV dif­frac­tion-lim­ited syn­chro­tron light source under con­struc­tion in Bei­jing. The main ac­cel­er­at­ing cav­ity adopted a quar­ter-wave β=1 struc­ture op­er­at­ing at 166 MHz while the third har­monic cav­ity uti­lized the sin­gle-cell el­lip­ti­cal geom­e­try at 500 MHz for the stor­age ring. The high beam cur­rent (200 mA) re­quires a strong damp­ing of higher order modes (HOMs) ex­cited in the su­per­con­duct­ing cav­i­ties. To meet the beam sta­bil­ity re­quire­ments, en­larged beam pipes with a di­am­e­ter of 505 mm for the 166 MHz cav­ity and 300 mm for the 500 MHz cav­ity were cho­sen to allow all HOMs to prop­a­gate along the beam tubes and to be damped by beam-line ab­sorbers. This paper pre­sents the HOM damp­ing scheme and the cav­ity im­ped­ance analy­sis re­sults. In ad­di­tion, power losses due to HOMs were also eval­u­ated for var­i­ous op­er­a­tion modes (high charge and high lu­mi­nos­ity) of the HEPS. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB090  
About • paper received ※ 17 May 2021       paper accepted ※ 22 June 2021       issue date ※ 11 August 2021  
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WEPAB098 Cryogenic Component and Material Testing for Compact Electron Beamlines cryogenics, cathode, electron, gun 2818
 
  • G.E. Lawler, N. Majernik, J.B. Rosenzweig
    UCLA, Los Angeles, California, USA
  
  Funding: This work was supported by the Center for Bright Beams, National Science Foundation Grant No. PHY-1549132 and DOE Contract DE-SC0020409
Cryo­genic regimes of op­er­a­tion are, for var­i­ous rea­sons, highly ad­van­ta­geous for nor­mal con­duct­ing ac­cel­er­a­tor struc­tures. Liq­uid cryo­gen-based sys­tems are costly to im­ple­ment and main­tain. As a re­sult, de­vel­op­ing cryo­genic test fa­cil­i­ties at a smaller more cost ef­fec­tive scale using cryo-cool­ers is at­trac­tive. Be­fore real im­ple­men­ta­tions of a cryo-cooler based beam­line, a sig­nif­i­cant amount of in­for­ma­tion is nec­es­sary re­gard­ing the be­hav­ior and prop­er­ties of var­i­ous com­po­nents and ma­te­ri­als at cryo­genic tem­per­a­tures. Find­ing this in­for­ma­tion lack­ing for our par­tic­u­lar beam­line case and by ex­ten­sion sim­i­lar elec­tron beam­lines, we en­deavor to gen­er­ate a thor­ough beam­line-rel­e­vant ma­te­r­ial and com­po­nent prop­er­ties down to the range of a liq­uid ni­tro­gen tem­per­a­tures (77 K) and the nom­i­nal op­er­at­ing tem­per­a­ture of a mod­est Gif­ford-McMa­hon cry­ocooler (45 K). 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB098  
About • paper received ※ 19 May 2021       paper accepted ※ 01 July 2021       issue date ※ 18 August 2021  
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WEPAB110 Solid-State Driven X-Band Linac for Electron Microscopy electron, linac, simulation, gun 2853
 
  • A. Dhar, E.A. Nanni, M.A.K. Othman, S.G. Tantawi
    SLAC, Menlo Park, California, USA
  
  Funding: This work was supported by the Department of Energy Contract No. DE-AC02-76SF00515.
Mi­cro­crys­tal elec­tron dif­frac­tion (Mi­croED) is a tech­nique used by sci­en­tists to image mol­e­c­u­lar crys­tals with cryo-elec­tron mi­croscopy (cryo-EM)*. How­ever, cryo-EMs re­main ex­pen­sive, lim­it­ing Mi­croED’s ac­ces­si­bil­ity. Cur­rent cryo-EMs ac­cel­er­ate elec­trons to 200-300 keV using DC elec­tron guns with a nA of cur­rent and low emit­tance. How­ever at higher volt­ages these DC guns rapidly grow in size. Re­plac­ing these elec­tron guns with a com­pact linac pow­ered by solid-state sources could lower cost while main­tain­ing beam qual­ity, thereby in­creas­ing ac­ces­si­bil­ity. Uti­liz­ing com­pact high shunt im­ped­ance X-band struc­tures en­sures that each RF cycle con­tains at most a few elec­trons, pre­serv­ing beam co­her­ence. CW op­er­a­tion of the RF linac is pos­si­ble with dis­trib­uted solid-state ar­chi­tec­tures** that use 100W solid-state am­pli­fiers at X-band fre­quen­cies. We pre­sent an ini­tial de­sign for a pro­to­type low-cost CW RF linac for high-through­put Mi­croED pro­duc­ing 200 keV elec­trons with a stand­ing-wave ar­chi­tec­ture where each cell is in­di­vid­u­ally pow­ered by a solid-state am­pli­fier. This de­sign also pro­vides an up­grade path for fu­ture com­pact MeV-scale sources on the order of 1 meter in size.
* Jones, C. G. et al. ACS central science 4, 1587-1592 (2018).
** D. C. Nguyen et al, Proc. 9th International Particle Accelerator Conference (IPAC’18), no. 9, pp. 520-523 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB110  
About • paper received ※ 19 May 2021       paper accepted ※ 24 June 2021       issue date ※ 19 August 2021  
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WEPAB138 Superconducting RF Gun with High Current and the Capability to Generate Polarized Electron Beams gun, SRF, electron, cathode 2936
 
  • I. Petrushina
    SUNY SB, Stony Brook, New York, USA
  • S.A. Belomestnykh, S. Kazakov, T.N. Khabiboulline, M. Martinello, Y.M. Pischalnikov, V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
  • J.C. Brutus, P. Inacker, Y.C. Jing, V. Litvinenko, J. Skaritka, E. Wang
    BNL, Upton, New York, USA
  • J.M. Grames, M. Poelker, R. Suleiman, E.J-M. Voutier
    JLab, Newport News, Virginia, USA
  
  High-cur­rent low-emit­tance CW elec­tron beams are in­dis­pens­able for nu­clear and high-en­ergy physics fixed tar­get and col­lider ex­per­i­ments, cool­ing high en­ergy hadron beams, gen­er­at­ing CW beams of mono­en­er­getic X-rays (in FELs) and gamma-rays (in Comp­ton sources). Po­lar­iza­tion of elec­trons in these beams pro­vides extra value by open­ing a new set of ob­serv­ables and fre­quently im­prov­ing the data qual­ity. We re­port on the up­grade of the unique and fully func­tional CW SRF 1.25 MeV SRF gun, built as part of the Co­her­ent elec­tron Cool­ing (CeC) pro­ject, which has demon­strated sus­tained CW op­er­a­tion with CsK2Sb pho­to­cath­odes gen­er­at­ing elec­tron bunches with record-low trans­verse emit­tances and record-high bunch charge ex­ceed­ing 10 nC. We pro­pose to ex­tend the ca­pa­bil­i­ties of this sys­tem to high av­er­age cur­rent of 100 mil­liampere in two steps: in­creas­ing the cur­rent 30-fold at each step with the goal to demon­strate re­li­able long-term op­er­a­tion of the high-cur­rent low-emit­tance CW SRF guns. We also pro­pose to test po­lar­ized GaAs pho­to­cath­odes in the ul­tra-high vac­uum (UHV) en­vi­ron­ment of the SRF gun, which has never been suc­cess­fully demon­strated in RF ac­cel­er­a­tors.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB138  
About • paper received ※ 25 May 2021       paper accepted ※ 29 July 2021       issue date ※ 23 August 2021  
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WEPAB148 RF Design of an X-Band TM02 Mode Cavity for Field Emitter Testing electron, coupling, insertion, multipactoring 2961
 
  • Z. Li, S.G. Tantawi
    SLAC, Menlo Park, California, USA
  • S.V. Baryshev, T. Posos, M.E. Schneider
    Michigan State University, East Lansing, Michigan, USA
  
  Funding: Work at SLAC was supported by DOE under contract No. DE-AC02-76SF00515. Work at MSU was supported by DOE under Award No. DE-SC0020429 and under Cooperative Agreement Award No. DE-SC0018362.
Pla­nar poly­crys­talline syn­thetic di­a­mond with ni­tro­gen-dop­ing/in­cor­po­ra­tion was found to be a re­mark­able field emit­ter. It is ca­pa­ble of gen­er­at­ing a high charge beam and han­dling mod­er­ate vac­uum con­di­tions. In­te­grat­ing it with an ef­fi­cient RF cav­ity could there­fore pro­vide a com­pact elec­tron source for RF in­jec­tors. Un­der­stand­ing the per­for­mance met­rics of the emit­ter in RF fields is es­sen­tial to­ward de­vel­op­ing such a de­vice. We in­ves­ti­gated a test setup of the field emit­ter at the X-band fre­quency. The setup in­cluded an X-band cav­ity op­er­at­ing at the TM02 mode. The field emit­ter ma­te­r­ial will be plated on the tip of a in­ser­tion rod on the cav­ity back plate. Part of the back plate and the emit­ter rod are de­mount­able, al­low­ing for ex­change of the field emit­ters. The TM02 mode was cho­sen such that the de­sign of the de­mount­able back plate does not in­duce field en­hance­ment at the in­stal­la­tion gap. The cav­ity were op­ti­mized to achieve a high sur­face field at the emit­ter tip and a max­i­mum en­ergy gain of the emit­ted elec­trons at a given input power. We will pre­sent the RF and me­chan­i­cal de­sign of such a TM02 X-band cav­ity for field emit­ter test­ing. 		 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB148  
About • paper received ※ 14 May 2021       paper accepted ※ 12 July 2021       issue date ※ 25 August 2021  
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WEPAB149 The RF Gun for the Siberian Circular Light Source "SKIF" gun, cathode, electron, linac 2965
 
  • V. Volkov, A.M. Batrakov, S.M. Gurov, S.E. Karnaev, A.A. Kondakov, S.A. Krutikhin, G.Y. Kurkin, A.E. Levichev, O.I. Meshkov, V.K. Ovchar, A.V. Pavlenko, O.A. Pavlov, A.G. Tribendis, N.G. Vasileva
    BINP SB RAS, Novosibirsk, Russia
  • A.E. Levichev, A.V. Pavlenko
    NSU, Novosibirsk, Russia
  • A.G. Tribendis
    NSTU, Novosibirsk, Russia
  
  The Siber­ian Cir­cu­lar Light Source is a new medium-en­ergy high bright­ness syn­chro­tron light fa­cil­ity that is under con­struc­tion on the Bud­ker In­sti­tute of Nu­clear Physics (BINP) in Rus­sia, Novosi­birsk. The ac­cel­er­a­tor fa­cil­ity is di­vided for con­ve­nience into three com­po­nents; a 3 GeV stor­age ring, a full-en­ergy booster syn­chro­tron, and a 200 MeV in­jec­tor linac with a thermionic grid­ded RF gun elec­tron source. This paper de­scribes the RF gun de­sign and plans for op­er­a­tions.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB149  
About • paper received ※ 19 May 2021       paper accepted ※ 07 June 2021       issue date ※ 10 August 2021  
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WEPAB150 Monotron Beam Break Up Instability Analysis HOM, klystron, dipole, resonance 2968
 
  • V. Volkov, V.M. Petrov
    BINP SB RAS, Novosibirsk, Russia
  
  New fea­tures of monotron beam break up (BBU) in­sta­bil­ity such as the typ­ing of high order mono­pole modes (HOMs)in each cav­ity by two classes one of them are sta­ble and other ones are un­sta­ble, HOM ef­fec­tive qual­ity fac­tor de­pend­ing on av­er­age beam cur­rent, and nor­mal­ized in­vari­able thresh­old cur­rent in­di­vid­u­ally char­ac­ter­izes each HOM are in­ves­ti­gated in this ar­ti­cle in de­tail.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB150  
About • paper received ※ 19 May 2021       paper accepted ※ 09 June 2021       issue date ※ 10 August 2021  
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WEPAB151 Regenerative Beam Break Up Instability Analysis HOM, dipole, linac, experiment 2971
 
  • V. Volkov, V.M. Petrov
    BINP SB RAS, Novosibirsk, Russia
  
  New fea­tures of re­gen­er­a­tive beam break up (BBU) in­sta­bil­ity such as the typ­ing of high order di­pole modes (HOMs)in each cav­ity by two classes, one of them are sta­ble and other ones are un­sta­ble, HOM ef­fec­tive qual­ity fac­tor de­pend­ing on av­er­age beam cur­rent, and nor­mal­ized in­vari­able thresh­old cur­rent in­di­vid­u­ally char­ac­ter­izes each HOM are in­ves­ti­gated in this ar­ti­cle in de­tail.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB151  
About • paper received ※ 19 May 2021       paper accepted ※ 22 June 2021       issue date ※ 10 August 2021  
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WEPAB165 Metamaterial Waveguide HOM Loads for SRF Accelerating Cavities HOM, GUI, vacuum, SRF 2994
 
  • S.V. Kuzikov
    Euclid TechLabs, Solon, Ohio, USA
  
  Sup­pres­sion of beam in­duced HOMs is nec­es­sary for most SRF ac­cel­er­at­ing cav­i­ties dri­ven with high cur­rents. One of the prob­lems in de­sign of a HOM load is that vac­uum com­pat­i­ble ma­te­ri­als with high enough imag­i­nary part of the di­elec­tric per­mit­tiv­ity, which pro­vides ab­sorp­tion, have also a high real part of the per­mit­tiv­ity. This does not allow ab­sorb­ing RF ra­di­a­tion at short dis­tance and in broad fre­quency band. We pro­pose con­sid­er­ing ar­ti­fi­cial meta­ma­te­ri­als where be­sides lossy di­elec­tric pieces, an ab­sorber with high mag­netic per­me­abil­ity is in­cluded. In our pro­posal, we sug­gest com­pos­ing a wave­guide HOM load of a meta­ma­te­r­ial con­sisted of well-known ce­ramic and fer­rite plates placed pe­ri­od­i­cally in a stack. Such a de­sign pro­vides low re­turn losses, com­pact­ness and broad fre­quency range of the op­er­a­tion.  
poster icon Poster WEPAB165 [1.844 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB165  
About • paper received ※ 19 May 2021       paper accepted ※ 02 June 2021       issue date ※ 15 August 2021  
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WEPAB177 Consideration of Triple-Harmonic Operation for the J-PARC RCS operation, bunching, injection, simulation 3020
 
  • H. Okita
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  • M. Furusawa, Y. Sugiyama
    KEK, Tokai, Ibaraki, Japan
  • K. Hara, K. Hasegawa, M. Nomura, C. Ohmori, T. Shimada, F. Tamura, M. Yamamoto, M. Yoshii
    KEK/JAEA, Ibaraki-Ken, Japan
  
  The wide­band mag­netic alloy (MA) cav­i­ties are em­ployed in the J-PARC RCS. The dual-har­monic op­er­a­tion, in which each MA cav­ity is dri­ven by su­per­po­si­tion of the fun­da­men­tal ac­cel­er­at­ing volt­age and the sec­ond har­monic volt­age, sig­nif­i­cantly im­proves the bunch­ing fac­tor and is in­dis­pens­able for ac­cel­er­a­tion of the high in­ten­sity beams. The orig­i­nal LLRF con­trol sys­tem was re­placed with the new sys­tem in 2019, which can con­trol the am­pli­tudes of the higher har­mon­ics as well as the fun­da­men­tal and sec­ond har­mon­ics. There­fore we con­sider to use ad­di­tion­ally the third har­monic volt­age for fur­ther im­prove­ment of the bunch­ing fac­tor dur­ing ac­cel­er­a­tion. By the triple-har­monic op­er­a­tion, the flat RF bucket can be re­al­ized with a higher syn­chro­nous phase and im­prove­ment of the bunch­ing fac­tor is ex­pected. In this pre­sen­ta­tion, we de­scribe the lon­gi­tu­di­nal sim­u­la­tion stud­ies of the triple-har­monic op­er­a­tion. Also the pre­lim­i­nary test re­sults are pre­sented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB177  
About • paper received ※ 18 May 2021       paper accepted ※ 25 June 2021       issue date ※ 18 August 2021  
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WEPAB209 Review of Medical Accelerator Development at Sameer, India linac, electron, photon, acceleration 3113
 
  • T.S. Dixit, N. Bansode, A.P. Bhagwat, S.T. Chavan, A.P. Deshpande, G. Gaikwad, S. Ghosh, R. Krishnan, C.S. Nainwad, G.D. Panchal, S.N. Pethe, K.A. Thakur, V.B. Ukey, M.M. Vidwans
    SAMEER, Mumbai, India
  
  Funding: Ministry of Electronics and Information Technology (MeitY), Government of India
At the Med­ical Elec­tron­ics Di­vi­sion of SAMEER, R&D for the de­vel­op­ment of a 4 MeV en­ergy elec­tron linac for Can­cer ther­apy was taken up in the late ’80s. An S-band stand­ing wave side cou­pled struc­ture op­er­at­ing at pi/2 mode was de­vel­oped for elec­tron ac­cel­er­a­tion. The linac was in­te­grated with other sub­sys­tems in col­lab­o­ra­tion with CSIO and PGIMER and the first ma­chine was com­mis­sioned at PGI, Chandi­garh in 1990. There­after, a lot of mod­i­fi­ca­tions like en­ergy, dose rate, iso-cen­ter height etc. were made in the sys­tem, and later 4 more ma­chines were com­mis­sioned in hos­pi­tals for treat­ment. More than 1,50,000 pa­tients have been treated using SAMEER’s 6 MeV on­col­ogy sys­tem. Sub­se­quently, de­vel­op­ment of dual-mode and vari­able en­ergy elec­tron and pho­ton out­put ma­chines was un­der­taken. Two-pho­ton en­er­gies of 6 and 15 MV and mul­ti­ple elec­tron en­er­gies start­ing from 6 to 18 MeV for treat­ment was of­fered from the linac. The elec­tron en­ergy vari­a­tion was done using plunger mech­a­nism in the side cou­pling cav­ity. This linac was suc­cess­fully baked and RF tested for var­i­ous pa­ra­me­ters. This paper de­scribes the ex­per­i­men­tal pa­ra­me­ters achieved for both low and high en­ergy dual-mode linac. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB209  
About • paper received ※ 14 May 2021       paper accepted ※ 07 July 2021       issue date ※ 01 September 2021  
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WEPAB244 Optimization and Machine Learning Applied to the RF Manipulations of Proton Beams in the CERN PS beam-loading, operation, extraction, simulation 3201
 
  • A. Lasheen, H. Damerau, S.C. Johnston
    CERN, Meyrin, Switzerland
  
  The 25 ns bunch spac­ing in the LHC is de­fined by a se­quence of RF ma­nip­u­la­tions in the Pro­ton Syn­chro­tron (PS). Mul­ti­ple RF sys­tems cov­er­ing a large range of rev­o­lu­tion har­mon­ics (7 to 21, 42, 84, 168) allow per­form­ing RF ma­nip­u­la­tions such as beam split­ting, and non-adi­a­batic bunch short­en­ing. For the nom­i­nal beam sent to LHC, each bunch is split in 12 in the PS. The rel­a­tive am­pli­tude and phase set­tings of the RF sys­tems need to be pre­cisely ad­justed to min­i­mize the bunch-by-bunch vari­a­tions in in­ten­sity, lon­gi­tu­di­nal emit­tance, and bunch shape. How­ever, due to tran­sient beam-load­ing, the ideal set­tings, as well as the best achiev­able beam qual­ity, vary with beam in­ten­sity. Slow drifts of the hard­ware may also af­fect beam qual­ity. In this paper, au­tom­a­tized op­ti­miza­tion rou­tines based on par­ti­cle sim­u­la­tions with in­ten­sity ef­fects are pre­sented, to­gether with the first con­sid­er­a­tions of ma­chine learn­ing. The op­ti­miza­tion rou­tines are used to as­sess the best achiev­able lon­gi­tu­di­nal beam qual­ity ex­pected with the PS RF sys­tems up­grades, in the frame­work of the LHC In­jec­tor Up­grade pro­ject.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB244  
About • paper received ※ 19 May 2021       paper accepted ※ 01 July 2021       issue date ※ 19 August 2021  
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WEPAB254 Design of a 10 MeV Beamline at the Upgraded Injector Test Facility for e-Beam Irradiation electron, radiation, solenoid, focusing 3232
 
  • X. Li, H. Baumgart, G. Ciovati
    ODU, Norfolk, Virginia, USA
  • G. Ciovati, F.E. Hannon, S. Wang
    JLab, Newport News, Virginia, USA
  
  Funding: Jefferson lab LDRD.
Elec­tron beam ir­ra­di­a­tion near 10 MeV is suit­able for waste­water treat­ment. The Up­graded In­jec­tor Test Fa­cil­ity (UITF) at Jef­fer­son Lab is a CW su­per­con­duct­ing lin­ear ac­cel­er­a­tor ca­pa­ble of pro­vid­ing an elec­tron beam of en­ergy up to 10 MeV and up to 100 µA cur­rent. This con­tri­bu­tion pre­sents the beam trans­port sim­u­la­tions for a beam­line to be used for the ir­ra­di­a­tion of waste­water sam­ples at the UITF. The sim­u­la­tions were done using the code Gen­eral Par­ti­cle Tracer with the goal of ob­tain­ing an 8 MeV elec­tron beam of ra­dius (3-σ) of ~2.4 cm. The achieved en­ergy spread is ~74.5 keV. The space charge ef­fects were in­ves­ti­gated when the bunch charge is var­ied to be up to 1000 times and the re­sults showed that they do not af­fect the beam qual­ity sig­nif­i­cantly. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB254  
About • paper received ※ 20 May 2021       paper accepted ※ 25 June 2021       issue date ※ 18 August 2021  
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WEPAB258 Beam Dynamics Design of a 162.5 MHz Superconducting RFQ Accelerator rfq, emittance, accelerating-gradient, focusing 3248
 
  • Ying. Xia, H.P. Li, Y.R. Lu, Q.Y. Tan, Z. Wang
    PKU, Beijing, People’s Republic of China
  • Y.R. Lu
    IAP, Frankfurt am Main, Germany
  
  Su­per­con­duct­ing(SC) RFQ has lower power con­sump­tion, larger aper­ture and higher ac­cel­er­at­ing gra­di­ent than room tem­per­a­ture RFQ. We plan to de­sign a 162.5MHz SC RFQ to ac­cel­er­ate the 30 mA pro­ton beams from 35 keV to 2.5 MeV, which will be used as a neu­tron source for BNCT and neu­tron imag­ing pro­ject. At an in­ter-vane volt­age of 180kV, the beam dy­nam­ics de­sign was car­ried out with ac­cept­able peak sur­face elec­tric field, high trans­mis­sion ef­fi­ciency, and rel­a­tively short cav­ity length.  
poster icon Poster WEPAB258 [1.251 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB258  
About • paper received ※ 17 May 2021       paper accepted ※ 06 July 2021       issue date ※ 13 August 2021  
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WEPAB293 The Trip Event Logger for Online Fault Diagnosis at the European XFEL controls, FEL, operation, EPICS 3344
 
  • J.H.K. Timm, J. Branlard, A. Eichler, H. Schlarb
    DESY, Hamburg, Germany
  
  The low-level RF (LLRF) sys­tem at the Eu­ro­pean XFEL, DESY, is of major im­por­tance for a high-per­for­mant and re­li­able op­er­a­tion. Faults here can jeop­ar­dize the over­all op­er­a­tion. There­fore, the trip event log­ger is cur­rently de­vel­opped, - a fault di­ag­no­sis tool to de­tect er­rors on­line, in­form the op­er­a­tors and trig­ger au­to­matic su­per­vi­sory ac­tions. Fur­ther goals are to pro­vide in­for­ma­tion for a fault tree and event tree analy­sis as well as a data­base of la­beled faulty data sets for of­fline analy­sis. The tool is based on the C++ frame­work ChimeraTK Ap­pli­ca­tion Core. With this close in­ter­con­nec­tion to the con­trol sys­tem it is pos­si­ble not only to mon­i­tor but also to in­ter­vene as it is of great im­por­tance for su­per­vi­sory tasks. The core of the tool con­sists of fault analy­sis mod­ules rang­ing from sim­ple ones (e.g., limit check­ing) to ad­vanced ones (model-based, ma­chine learn­ing, etc.). Within this paper the ar­chi­tec­ture and the im­ple­men­ta­tion of the trip event log­ger are pre­sented.  
poster icon Poster WEPAB293 [7.919 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB293  
About • paper received ※ 19 May 2021       paper accepted ※ 02 July 2021       issue date ※ 21 August 2021  
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WEPAB295 Parameter Estimation of Short Pulse Normal-Conducting Standing Wave Cavities gun, coupling, RF-structure, resonance 3351
 
  • S. Pfeiffer, J. Branlard, F. Burkart, M. Hoffmann, H. Schlarb
    DESY, Hamburg, Germany
  
  The lin­ear ac­cel­er­a­tor ARES (Ac­cel­er­a­tor Re­search Ex­per­i­ment at SIN­BAD) is a new re­search fa­cil­ity at DESY. Elec­tron bunches with a max­i­mum rep­e­ti­tion rate of 50 Hz are ac­cel­er­ated to a tar­get en­ergy of 155 MeV. The fa­cil­ity aims for ul­tra-sta­ble sub-fem­tosec­ond ar­rival-times and high peak-cur­rents at the ex­per­i­ment, plac­ing high de­mands on the ref­er­ence dis­tri­b­u­tion and field reg­u­la­tion of the RF struc­ture. In this con­tri­bu­tion, we pre­sent the phys­i­cal pa­ra­me­ter es­ti­ma­tion of key RF prop­er­ties such as cav­ity de­tun­ing not di­rectly mea­sur­able on the RF field decay. The method can be used as a fast mon­i­tor of inner cell tem­per­a­ture. The es­ti­mated prop­er­ties are fi­nally com­pared with the mea­sured ones.  
poster icon Poster WEPAB295 [0.860 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB295  
About • paper received ※ 19 May 2021       paper accepted ※ 05 July 2021       issue date ※ 10 August 2021  
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WEPAB297 A Recent Upgrade on Phase Drift Compensation System for a Stable Beam Injection at J-PARC Linac linac, DTL, injection, controls 3357
 
  • E. Cicek, Z. Fang, Y. Fukui, K. Futatsukawa
    KEK, Ibaraki, Japan
  • T. Hirane, S. Shinozaki
    JAEA/J-PARC, Tokai-mura, Japan
  • Y. Sato
    Nippon Advanced Technology Co., Ltd., Tokai, Japan
  
  J-PARC linac, con­sist­ing of 324 MHz and 972 MHz ac­cel­er­a­tion sec­tions, de­liv­ers H− beam to the rapid cy­cling syn­chro­tron (RCS). The drift in the beam in­jec­tion mo­men­tum from linac to RCS was mea­sured to be highly de­pen­dent on the hu­mid­ity at the kly­stron gallery. Also, changes in both tem­per­a­ture and hu­mid­ity strongly af­fect the rf field phase con­trolled within the dig­i­tal feed­back (DFB) sys­tem. To cope with this, a unique phase drift com­pen­sa­tion sys­tem, namely the phase drift mon­i­tor (PDM) sys­tem, is im­ple­mented in the MEBT2B1 sta­tion as the first step at the linac. How­ever, the com­pen­sa­tion of the drift cor­rec­tion could not be achieved di­rectly since two dif­fer­ent fre­quen­cies were used. The new PDM, which adapts the di­rect sam­pling method using the Radio Fre­quency Sys­tem-on-Chip (RFSoC), will pave the way to en­sure rf phase sta­bil­ity at all sta­tions si­mul­ta­ne­ously. Here we pre­sent the ef­fects of tem­per­a­ture and hu­mid­ity on the rf field phase, along with per­for­mance and pre­lim­i­nary test re­sults con­cern­ing the phase drift com­pen­sa­tion.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB297  
About • paper received ※ 19 May 2021       paper accepted ※ 01 July 2021       issue date ※ 30 August 2021  
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WEPAB299 Spallation Neutron Source Proton Power Upgrade Low-Level RF Control System Development controls, LLRF, operation, neutron 3363
 
  • M.T. Crofford, J.A. Ball, J.E. Breeding, M.P. Martinez, J.S. Moss, M. Musrock
    ORNL, Oak Ridge, Tennessee, USA
  • L.R. Doolittle, C. Serrano, V.K. Vytla
    LBNL, Berkeley, California, USA
  • J. Graham, C.K. Roberts, J.W. Sinclair, Z. Sorrell, S. Whaley
    ORNL RAD, Oak Ridge, Tennessee, USA
  
  Funding: * This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under contract number DE-AC05-00OR22725.
The Pro­ton Power Up­grade (PPU) Pro­ject is ap­proved for the Spal­la­tion Neu­tron Source at Oak Ridge Na­tional Lab­o­ra­tory and will dou­ble the pro­ton beam power ca­pa­bil­ity from 1.4 MW to 2.8 MW with 2 MW beam power avail­able to the first tar­get sta­tion. A sec­ond tar­get sta­tion is planned and will uti­lize the re­main­ing beam power in the fu­ture. The pro­ton power in­crease will be sup­ported with the ad­di­tion of twenty-eight new su­per­con­duct­ing cav­i­ties pow­ered by 700 kW peak power kly­strons to in­crease beam en­ergy while in­creases to the beam cur­rent will be done with a com­bi­na­tion of ex­ist­ing RF mar­gin, and DTL HPRF up­grades. The orig­i­nal low-level RF con­trol sys­tem has proven to be re­li­able over the past 15 years of op­er­a­tions, but ob­so­les­cence is­sues man­date a re­place­ment sys­tem be de­vel­oped for the PPU pro­ject. The re­place­ment sys­tem is re­al­ized in a µTCA.4 plat­form using a com­bi­na­tion of com­mer­cial off-the-shelf boards and cus­tom hard­ware to sup­port the re­quire­ments of PPU. This paper pre­sents the pro­to­type hard­ware, firmware, and soft­ware de­vel­op­ment ac­tiv­i­ties along with pre­lim­i­nary test­ing re­sults of the new sys­tem. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB299  
About • paper received ※ 18 May 2021       paper accepted ※ 21 June 2021       issue date ※ 12 August 2021  
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WEPAB300 Python Based Tools for FRIB LLRF Operation and Management controls, LLRF, EPICS, linac 3367
 
  • S.R. Kunjir, D.G. Morris, S. Zhao
    FRIB, East Lansing, Michigan, USA
  
  Funding: This work is supported by the US Department of Energy Office of Science under Cooperative Agreement DE-SC0000661, the State of Michigan and Michigan State University.
Some Python based tools have been de­vel­oped at the Fa­cil­ity for Rare Iso­tope Beams (FRIB) for the ease of op­er­a­tion and man­age­ment of the low level radio fre­quency (LLRF) con­trollers. Uti­liz­ing the rich fea­tures in Python, some tasks can be eas­ily ap­plied to a whole seg­ment, one type of cry­omod­ule (CM), a spe­cific cry­omod­ule or in­di­vid­ual cav­i­ties grouped by a com­plex cus­tom query. The tasks in­clude, for ex­am­ple, 1) test­ing in­ter­face con­nec­tions be­tween var­i­ous sub-sys­tems prior to an op­er­a­tional run; 2) set­ting, check­ing and sav­ing/restor­ing pa­ra­me­ters dur­ing and after an op­er­a­tional run; 3) up­dat­ing LLRF con­troller firmware and soft­ware dur­ing main­te­nance. With these tools, rou­tine man­ual tasks are stream­lined to achieve sig­nif­i­cantly greater ef­fi­ciency in terms of scal­a­bil­ity, time, mem­ory and net­work re­sources. Con­sid­er­ing chan­nel ac­cess se­cu­rity, beam on/off sta­tus etc., the strat­egy of choos­ing ei­ther input/out­put con­troller (IOC) or Python for the im­ple­men­ta­tion of cer­tain tasks is also dis­cussed in the paper. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB300  
About • paper received ※ 18 May 2021       paper accepted ※ 01 July 2021       issue date ※ 29 August 2021  
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WEPAB301 Design of an X-Band LLRF System for TEX Test Facility at LNF-INFN LLRF, klystron, insertion, GUI 3371
 
  • L. Piersanti, D. Alesini, M. Bellaveglia, S. Bini, B. Buonomo, F. Cardelli, C. Di Giulio, M. Diomede, A. Falone, G. Franzini, A. Gallo, A. Liedl, S. Pioli, S. Quaglia, L. Sabbatini, M. Scampati, G. Scarselletta, A. Stella
    INFN/LNF, Frascati, Italy
  
  Funding: Latino is a project co-funded by Regione Lazio within POR-FESR 2014-2020 program
In the frame­work of LATINO pro­ject (Lab­o­ra­tory in Ad­vanced Tech­nolo­gies for IN­nO­va­tion) funded by Lazio re­gional gov­ern­ment, a TEst stand for X-band (TEX) is being com­mis­sioned at Fras­cati Na­tional Lab­o­ra­to­ries (LNF) of INFN. TEX is born as a col­lab­o­ra­tion with CERN, aimed at car­ry­ing out high power tests of X-band ac­cel­er­at­ing struc­ture pro­to­types and wave­guide com­po­nents, and it is of para­mount im­por­tance in view of the con­struc­tion of EuPRAXIA@​SPARC_​LAB fa­cil­ity at LNF. In order to gen­er­ate, ma­nip­u­late and mea­sure the RF pulses needed to feed the RF power unit (solid state Scan­di­Nova K400 mod­u­la­tor, CPI 50 MW 50 Hz kly­stron) an X-band low level RF sys­tem has been de­vel­oped, mak­ing use of a com­mer­cial S-band (2.856 GHz) Lib­era dig­i­tal LLRF (man­u­fac­tured by In­stru­men­ta­tion Tech­nolo­gies) with a newly de­signed up/down con­ver­sion stage and a ref­er­ence gen­er­a­tion/dis­tri­b­u­tion sys­tem, which is able to pro­duce co­her­ent ref­er­ence fre­quen­cies for the Amer­i­can S-band (2.856 GHz) and Eu­ro­pean X-band (11.994 GHz). In this paper the main fea­tures of such sys­tems will be re­viewed to­gether with pre­lim­i­nary lab­o­ra­tory mea­sure­ment re­sults. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB301  
About • paper received ※ 19 May 2021       paper accepted ※ 12 July 2021       issue date ※ 16 August 2021  
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WEPAB322 Status of Digital BPM Signal Processor for SHINE FPGA, FEL, electron, electronics 3430
 
  • L.W. Lai, F.Z. Chen, Y.B. Leng, T. Wu, Y.M. Zhou
    SSRF, Shanghai, People’s Republic of China
  • J. Wan
    SINAP, Shanghai, People’s Republic of China
  
  Funding: Youth Innovation Promotion Association, CAS (Grant No. 2019290); The National Key Research and Development Program of China (Grant No. 2016YFA0401903).
Dig­i­tal sig­nal proces­sors that can han­dle 1MHz bunch rate BPM sig­nal pro­cess­ing are under de­vel­op­ment for SHINE. Two dif­fer­ent proces­sors have been de­vel­oped at the same time, in­clud­ing an in­ter­me­di­ate fre­quency sig­nal proces­sor with a sam­pling rate higher than 500MHz, which can be used in gen­eral BPM ap­pli­ca­tions; and a di­rect RF sam­pling proces­sor, which can di­rectly sam­ple the C band cav­ity BPM sig­nal with­out ana­log down-con­ver­sion mod­ules and greatly sim­pli­fies the cav­ity BPM sys­tem. This paper will in­tro­duce the de­sign, de­vel­op­ment sta­tus, and per­for­mance eval­u­a­tions of the proces­sors. 		 
poster icon Poster WEPAB322 [1.919 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB322  
About • paper received ※ 20 May 2021       paper accepted ※ 10 June 2021       issue date ※ 24 August 2021  
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WEPAB329 LCLS-II Average Current Monitor vacuum, coupling, simulation, network 3443
 
  • P. Borchard, J.S. Hoh
    Dymenso LLC, San Francisco, USA
  
  The LCLS-II pro­ject at SLAC is a high power up­grade to the ex­ist­ing free-elec­tron laser fa­cil­ity. The LCLS-II Ac­cel­er­a­tor Sys­tem will in­clude a new 4 GeV con­tin­u­ous-wave su­per­con­duct­ing lin­ear ac­cel­er­a­tor in the first kilo­me­ter of the SLAC lin­ear ac­cel­er­a­tor tun­nel and sup­ple­ments the ex­ist­ing low power pulsed linac. Av­er­age Cur­rent Mon­i­tors (ACMs) are needed to pro­tect against ex­ces­sive beam power which might oth­er­wise cause dam­age to the beam dumps. The ACM cav­i­ties are pill­box-shaped stain­less steel RF cav­ity with two ra­dial probe ports with cou­plers, one ra­dial test port with a cou­pler, and a mech­a­nism for me­chan­i­cally fine-tun­ing the cav­ity res­o­nant fre­quency. The ACM RF cav­i­ties will be lo­cated at points of known or con­strained beam en­ergy and will mon­i­tor the beam cur­rent, a safety sys­tem will trip off the beam if the beam power ex­ceeds the al­lowed value.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB329  
About • paper received ※ 19 May 2021       paper accepted ※ 16 June 2021       issue date ※ 12 August 2021  
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WEPAB358 Development of Low-Z Collimator for SuperKEKB impedance, electron, positron, operation 3537
 
  • S. Terui, T. Abe, Y. Funakoshi, T. Ishibashi, H.N. Nakayama, K. Ohmi, D. Zhou
    KEK, Ibaraki, Japan
  • A. Natochii
    University of Hawaii, Honolulu,, USA
  
  Col­li­ma­tor jaws for Su­perKEKB main ring, which is an elec­tron-positron col­lider, in­stalled to sup­press back­ground noise in a par­ti­cle de­tec­tor com­plex named Belle II. The col­li­ma­tors are suc­cess­ful to re­duce back­grounds when the col­li­ma­tor was closed. But, in high cur­rent op­er­a­tions with 500 mA or more, jaws were oc­ca­sion­ally dam­aged by hit­ting ab­nor­mal beams. This trou­ble is a low-fre­quency, which is once-a-com­mis­sion­ing pe­riod cur­rently, but a high-con­se­quence one be­cause we are not able to apply high volt­age on de­tec­tors in Belle II by high back­grounds. Low-Z col­li­ma­tor jaw, that is durable through hit­ting un­con­trol­lable beam, have been de­signed due to pro­tect im­por­tant com­po­nent as the so­lu­tion of the trou­ble. The low-Z col­li­ma­tor jaws are in­stal­lable in a pre­sent col­li­ma­tor cham­ber, have a pair of ver­ti­cally op­posed mov­able jaws. One pair of low-Z col­li­ma­tor jaws was in­stalled. The paper is to de­scribe what did we cal­cu­late and mea­sure to make a low-Z col­li­ma­tor, how did we make a low-Z col­li­ma­tor, the im­pact of the in­stalled low-Z col­li­ma­tor, mainly trans­verse mode cou­pling in­sta­bil­ity.  
poster icon Poster WEPAB358 [0.788 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB358  
About • paper received ※ 16 May 2021       paper accepted ※ 22 July 2021       issue date ※ 31 August 2021  
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WEPAB381 Multipactor Simulations for MYRRHA Spoke Cavity: Comparison Between SPARK3D, MUSICC3D, CST PIC and Measurement multipactoring, electron, simulation, niobium 3606
 
  • N. Hu, M. Chabot, J.-L. Coacolo, D. Longuevergne, G. Olry
    Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
  • M.B. Belhaj
    ONERA, Toulouse, France
  
  The mul­ti­pactor ef­fect can lead to ther­mal break­down (quench), high field emis­sion and lim­ited ac­cel­er­at­ing gra­di­ent in su­per­con­duct­ing ac­cel­er­a­tor de­vices. To de­ter­mine the mul­ti­pactor break­down power level, mul­ti­pactor sim­u­la­tions can be per­formed. The ob­jec­tive of this study is to com­pare the re­sults given by dif­fer­ent sim­u­la­tion codes with the re­sults of ver­ti­cal test­ing of SRF cav­i­ties. In this paper, Spark3D, MU­S­IC­C3D and CST Stu­dio PIC solver have been used to sim­u­late the mul­ti­pactor ef­fect in Spoke cav­ity de­vel­oped within the frame­work of MYRRHA pro­ject. Then, a bench­mark of these three sim­u­la­tion codes has been made. The break­down power level, the mul­ti­pactor order and the most promi­nent lo­ca­tion of mul­ti­pactor are pre­sented. Fi­nally, the sim­u­la­tion re­sults are com­pared with the mea­sure­ments done dur­ing the ver­ti­cal tests.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB381  
About • paper received ※ 19 May 2021       paper accepted ※ 24 June 2021       issue date ※ 30 August 2021  
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WEPAB394 Development of a New Interlock and Data Acquisition for the RF System at High Energy Photon Source controls, EPICS, FPGA, PLC 3630
 
  • Z.W. Deng, J.P. Dai, H.Y. Lin, Q.Y. Wang, P. Zhang
    IHEP, Beijing, People’s Republic of China
  
  Funding: This work was supported by High Energy Photon Source, a major national science and technology infrastructure in China.
A new in­ter­lock and data ac­qui­si­tion (DAQ) sys­tem is being de­vel­oped for the RF sys­tem at High En­ergy Pho­ton Source (HEPS) to pro­tect es­sen­tial de­vices as well as to lo­cate the fault. Var­i­ous sig­nals col­lected and pre-processed by the DAQ sys­tem and in­di­vid­ual in­ter­lock sig­nals from solid-state power am­pli­fiers, low-level RFs, arc de­tec­tors, etc. are sent to the in­ter­lock sys­tem for logic de­ci­sion to con­trol the RF switch. Pro­gram­ma­ble logic con­trollers (PLC) are used to col­lect slow sig­nals like tem­per­a­ture, water flowrate, etc., while fast ac­qui­si­tion for RF sig­nals is re­al­ized by ded­i­cated boards with down-con­ver­sion fron­tend and dig­i­tal sig­nal pro­cess­ing boards. In order to im­prove the re­sponse time, field pro­gram­ma­ble gate array (FPGA) has been used for in­ter­lock logic im­ple­men­ta­tion with an em­bed­ded ex­per­i­men­tal physics and in­dus­trial con­trol sys­tem (EPICS). Data stor­age is man­aged by using EPICS Archiver Ap­pli­ance and an op­er­a­tor in­ter­face is de­vel­oped by using Con­trol Sys­tem Stu­dio (CSS) run­ning on a stand­alone com­puter. This paper pre­sents the de­sign and the first test of the new in­ter­lock and DAQ for HEPS RF sys­tem. 		 
poster icon Poster WEPAB394 [2.140 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB394  
About • paper received ※ 16 May 2021       paper accepted ※ 14 July 2021       issue date ※ 31 August 2021  
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WEPAB402 Status and Progress of the High-Power RF System for High Energy Photon Source booster, photon, GUI, storage-ring 3653
 
  • T.M. Huang, J. Li, H.Y. Lin, Y.L. Luo, Q. Ma, W.M. Pan, P. Zhang, F.C. Zhao
    IHEP, Beijing, People’s Republic of China
  
  Funding: Work was supported in part by High Energy Photon Source, a major national science and technology infrastructure in China, and in part by the National Natural Science Foundation of China(12075263).
High En­ergy Pho­ton Source is a 6-GeV dif­frac­tion-lim­ited syn­chro­tron light source cur­rently under con­struc­tion in Bei­jing. Three types of high-power RF sys­tems are used to drive the booster and the stor­age ring. For the booster ring, a total of 600-kW con­tin­u­ous-wave (CW) RF power is gen­er­ated by six 500-MHz solid-state power am­pli­fiers (SSA) and fed into six nor­mal-con­duct­ing cop­per cav­i­ties. Con­cern­ing the stor­age ring, five CW 260-kW SSAs at 166 MHz and two CW 260-kW SSAs at 500-MHz are used to drive five fun­da­men­tal and two third-har­monic su­per­con­duct­ing cav­i­ties re­spec­tively. The RF power dis­tri­b­u­tions are re­al­ized by 9-3/16" rigid coax­ial line for the 166-MHz sys­tem and EIA stan­dard WR1800 wave­guide for the 500-MHz one. High-power cir­cu­la­tors and loads are in­stalled at the out­puts of all SSAs to fur­ther pro­tect the power trans­mit­ters from dam­ages due to re­flected power al­though each am­pli­fier mod­ule is equipped with in­di­vid­ual iso­la­tors. The over­all sys­tem lay­out and the progress of the main com­po­nents are pre­sented in this paper. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB402  
About • paper received ※ 18 May 2021       paper accepted ※ 02 July 2021       issue date ※ 29 August 2021  
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THPAB002 Lattice Design for BEPCII Upgrade lattice, quadrupole, dynamic-aperture, electron 3756
 
  • H. Geng, W.B. Liu, J. Qiu, J. Xing, C.H. Yu, Y. Zhang
    IHEP, Beijing, People’s Republic of China
  
  The Bei­jing Elec­tron Positron Col­lider II (BEPCII) has achieved a se­ries of achieve­ments in high-en­ergy physics study. Along with the deep­en­ing of the re­search, more im­por­tant physics is ex­pected in higher en­ergy re­gions (>2.1 GeV). As the upper limit of BEPCII de­sign en­ergy is 2.1GeV, an ur­gent up­grade is re­quired for BEPCII. To achieve a higher lu­mi­nos­ity at higher en­ergy, the num­ber of RF cav­i­ties is ex­pected to be dou­bled. In this paper, the lat­tice de­sign for the up­grade of BEPCII is stud­ied. The dy­namic aper­ture track­ing re­sult shows that the lat­tice could meet the in­jec­tion re­quire­ment of the BEPCII beam with a rea­son­able mar­gin.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB002  
About • paper received ※ 14 May 2021       paper accepted ※ 17 June 2021       issue date ※ 01 September 2021  
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THPAB007 Technology Spinoff and Lessons Learned from the 4-Turn ERL CBETA permanent-magnet, radiation, SRF, linac 3762
 
  • K.E. Deitrick, N. Banerjee, A.C. Bartnik, D.C. Burke, J.A. Crittenden, J. Dobbins, C.M. Gulliford, G.H. Hoffstaetter, Y. Li, W. Lou, P. Quigley, D. Sagan, K.W. Smolenski
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • J.S. Berg, S.J. Brooks, R.L. Hulsart, G.J. Mahler, F. Méot, R.J. Michnoff, S. Peggs, T. Roser, D. Trbojevic, N. Tsoupas
    BNL, Upton, New York, USA
  • T. Miyajima
    KEK, Ibaraki, Japan
  
  The Cor­nell-BNL ERL Test Ac­cel­er­a­tor (CBETA) de­vel­oped sev­eral en­ergy-sav­ing mea­sures: multi-turn en­ergy re­cov­ery, low-loss su­per­con­duct­ing ra­diofre­quency (SRF) cav­i­ties, and per­ma­nent mag­nets. With green tech­nol­ogy be­com­ing im­per­a­tive for new high-power ac­cel­er­a­tors, the lessons learned will be im­por­tant for pro­jects like the FCC-ee or new light sources, where spin­offs and lessons learned from CBETA are al­ready con­sid­ered for mod­ern de­signs.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB007  
About • paper received ※ 20 May 2021       paper accepted ※ 05 July 2021       issue date ※ 28 August 2021  
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THPAB014 Matlab Simulations of the Helium Liquefier in the FREIA Laboratory simulation, HOM, interface, coupling 3781
 
  • E. Waagaard, R.J.M.Y. Ruber, V.G. Ziemann
    Uppsala University, Uppsala, Sweden
  
  We de­scribe sim­u­la­tions that track a state vec­tor with pres­sure, tem­per­a­ture, and gas flow through the he­lium liq­ue­fier in the FREIA lab­o­ra­tory. Most com­po­nents, in­clud­ing three-way heat ex­chang­ers, are rep­re­sented by ma­tri­ces that allow us to track the state through the sys­tem. The only non-lin­ear el­e­ment is the Joule-Thom­son valve, which is rep­re­sented by a non-lin­ear map for the state vari­ables. Re­al­is­tic prop­er­ties for the en­thalpy and other ther­mo­dy­namic quan­ti­ties are taken into ac­count with the help of the Cool­prop li­brary. The re­sult­ing sys­tem of equa­tions is rapidly solved by it­er­a­tion and shows good agree­ment with the ob­served LHe yield with and with­out ni­tro­gen pre-cool­ing.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB014  
About • paper received ※ 13 May 2021       paper accepted ※ 14 July 2021       issue date ※ 21 August 2021  
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THPAB015 Studies of the Imperfection in Crab Crossing Scheme for Electron-Ion Collider electron, solenoid, luminosity, proton 3784
 
  • Y. Hao, J.S. Berg, D. Holmes, Y. Luo, C. Montag
    BNL, Upton, New York, USA
  • V.S. Morozov
    JLab, Newport News, Virginia, USA
  • J. Qiang
    LBNL, Berkeley, California, USA
  • D. Xu
    FRIB, East Lansing, Michigan, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
Crab cross­ing scheme is the es­sen­tial scheme that ac­com­mo­dates large cross­ing angle with­out loss of lu­mi­nos­ity in the de­sign of Elec­tron-Ion col­lider (EIC). The ideal op­tics and phase ad­vances of the crab cav­ity pair are set to cre­ate a local crab­bing bump in the in­ter­ac­tion re­gion (IR). How­ever, there are al­ways small er­rors in the ac­tual lat­tice of IR. In this ar­ti­cle, we will pre­sent the sim­u­la­tion and an­a­lyt­i­cal stud­ies on the im­per­fec­tions in the crab cross­ing scheme in the EIC de­sign. The tol­er­ance of the im­per­fec­tion and the pos­si­ble reme­dies can be con­cluded from these stud­ies. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB015  
About • paper received ※ 17 May 2021       paper accepted ※ 16 July 2021       issue date ※ 30 August 2021  
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THPAB029 Dynamic Aperture Evaluation for the Hadron Storage Ring in the Electron-Ion Collider dynamic-aperture, electron, proton, dipole 3812
 
  • Y. Luo, J.S. Berg, M. Blaskiewicz, W. Fischer, X. Gu, H. Lovelace III, C. Montag, R.B. Palmer, S. Peggs, V. Ptitsyn, F.J. Willeke, H. Witte
    BNL, Upton, New York, USA
  • Y. Hao, D. Xu
    FRIB, East Lansing, Michigan, USA
  • H. Huang
    ODU, Norfolk, Virginia, USA
  • V.S. Morozov, E.A. Nissen, T. Satogata
    JLab, Newport News, Virginia, USA
  • J. Qiang
    LBNL, Berkeley, California, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The Elec­tron-Ion Col­lider (EIC) is aim­ing at a de­sign lu­mi­nos­ity of 1e34 cm-2s−1. To main­tain such a high lu­mi­nos­ity, both beams in the EIC need an ac­cept­able beam life­time in the pres­ence of the beam-beam in­ter­ac­tion. For this pur­pose, we car­ried out weak-strong el­e­ment-by-el­e­ment par­ti­cle track­ing to eval­u­ate the long-term dy­namic aper­ture for the hadron ring lat­tice de­sign. We im­proved our sim­u­la­tion code Sim­Track to treat some new lat­tice de­sign fea­tures, such as ra­di­ally off­set on-mo­men­tum or­bits, co­or­di­nate trans­for­ma­tions in the in­ter­ac­tion re­gion, etc. In this ar­ti­cle, we will pre­sent the pre­lim­i­nary dy­namic aper­ture cal­cu­la­tion re­sults with β*- func­tion scan, ra­dial orbit shift, cross­ing angle col­li­sion, and mag­netic field er­rors. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB029  
About • paper received ※ 17 May 2021       paper accepted ※ 31 August 2021       issue date ※ 01 September 2021  
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THPAB067 Simulation of the APS-U Orbit Motion Due to RF Noise simulation, synchrotron, resonance, photon 3911
 
  • V. Sajaev
    ANL, Lemont, Illinois, USA
  
  Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
APS Up­grade stor­age ring will keep the same rf sys­tem that is presently used at APS. This rf sys­tem has am­pli­tude and phase noise dom­i­nated by the lines at 60, 180, and 360 Hz. APS presently op­er­ates with syn­chro­tron fre­quency close to 2 kHz, which is far away from the rf noise fre­quen­cies, and still the rf sys­tem noise con­tributes over 2 mi­crom­e­ters rms into the hor­i­zon­tal orbit noise due to beam en­ergy vari­a­tion. APS-U will op­er­ate with a bunch-length­en­ing cav­ity, which will lower the syn­chro­tron fre­quency down to about 200 Hz. This could po­ten­tially lead to large orbit noise and other neg­a­tive con­se­quences due to en­ergy vari­a­tion caused by the rf sys­tem noise. In this paper, we will pre­sent sim­u­la­tions of the rf noise-in­duced orbit mo­tion at APS and APS-U and de­fine the rf am­pli­tude and phase noise re­quire­ments that need to be achieved for APS-U op­er­a­tion. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB067  
About • paper received ※ 12 May 2021       paper accepted ※ 13 July 2021       issue date ※ 22 August 2021  
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THPAB069 Design Concepts for a High-Gradient C-Band Linac FEL, electron, linac, accelerating-gradient 3919
 
  • T.B. Bolin, S.I. Sosa Guitron
    UNM-ECE, Albuquerque, USA
  • S. Biedron
    UNM-ME, Albuquerque, New Mexico, USA
  • J.R. Cary
    Tech-X, Boulder, Colorado, USA
  • M. Dal Forno
    SLAC, Menlo Park, California, USA
  
  Funding: This work was performed under Contract No. 89233218CNA000001, supported by the U.S. DOE’s National Nuclear Security Administration, for the operation of Los Alamos National Laboratory (LANL).
Dur­ing the last decade, the pro­duc­tion of soft to hard x-rays (up to 25 keV) at XFEL fa­cil­i­ties has en­abled new de­vel­op­ments in a broad range of dis­ci­plines. One caveat is that these in­stru­ments can re­quire a large amount of real es­tate. For ex­am­ple, the XFEL dri­ver is typ­i­cally an elec­tron beam lin­ear ac­cel­er­a­tor (LINAC) and the need for higher elec­tron beam en­er­gies ca­pa­ble of gen­er­at­ing higher en­ergy X-rays can re­quire longer linacs; costs quickly be­come pro­hib­i­tive, re­quir­ing state of art meth­ods. One cost-sav­ing mea­sure is to pro­duce a high ac­cel­er­at­ing gra­di­ent while re­duc­ing cav­ity size. Com­pact ac­cel­er­at­ing struc­tures are also high-fre­quency. Here, we de­scribe de­sign con­cepts for a high-gra­di­ent, cryo-cooled LINAC for XFEL fa­cil­i­ties in the C-band regime (~4-8 GHz). We are also ex­plor­ing C-band for dif­fer­ent ap­pli­ca­tions in­clud­ing dri­vers for se­cu­rity ap­pli­ca­tions. We in­ves­ti­gate 2 dif­fer­ent trav­el­ing wave (TW) geome­tries op­ti­mized for high-gra­di­ent op­er­a­tion as mod­eled with VSim soft­ware. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB069  
About • paper received ※ 20 May 2021       paper accepted ※ 02 July 2021       issue date ※ 13 August 2021  
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THPAB081 High-Power Prototype Canon Coupler for APS-U Booster Cavities booster, GUI, coupling, injection 3956
 
  • G.J. Waldschmidt, D.J. Bromberek, D. Horan, G. Trento, U. Wienands
    ANL, Lemont, Illinois, USA
  • T. Harada, H. Oikawa, H. Takahashi
    CETD, Tochigi, Japan
  
  The Ad­vanced Pho­ton Source Up­grade (APS-U) plans to achieve a beam cap­ture ef­fi­ciency above 90% at 17 nC bunch charge into the Booster. Due to large beam load­ing at in­jec­tion, the 352-MHz Booster cav­i­ties will be sig­nif­i­cantly de­tuned ne­ces­si­tat­ing ef­fec­tive-power han­dling much greater than the 100kW ef­fec­tive power rat­ing of the pre­sent cou­pler. Canon Elec­tron Tubes & De­vices Co., Ltd. (CETD) has de­signed and built a com­pact cou­pler for the APS-U Booster using a high-power ce­ramic disk win­dow de­sign in ad­di­tion to ac­com­mo­dat­ing sig­nif­i­cant space re­stric­tions and ad­di­tional di­ag­nos­tics and cool­ing re­quire­ments. The cou­pler de­sign was mod­i­fied from an ex­ist­ing 500MHz, 800kW cou­pler that has been in rou­tine op­er­a­tion at KEKB. The APS-U cou­pler has been in­stalled and tested in the high-power 352-MHz test stand at the APS. The de­tails of the de­sign and test­ing of the pro­to­type cou­pler will be re­ported in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB081  
About • paper received ※ 18 May 2021       paper accepted ※ 28 July 2021       issue date ※ 26 August 2021  
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THPAB083 Measurement of the Longitudinal Phase-Space of the APS Photo-Injector Beam linac, gun, dipole, lattice 3963
 
  • Y. Sun
    ANL, Lemont, Illinois, USA
  
  Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
An S-band photo-cath­ode RF gun (PCG) ex­ists at the front of the linac. The high-bright­ness pho­toin­jec­tor beam is ac­cel­er­ated by the linac and and can be used for ac­cel­er­a­tor tech­nol­ogy and beam physics R&D ex­per­i­ments in the Linac Ex­ten­sion Area (LEA). For some ap­pli­ca­tions, the beam needs to be com­pressed by a mag­netic bunch com­pres­sor in the mid­dle of the linac. An S-band trans­verse-mode cav­ity (Tcav) is avail­able at the end of the linac for beam lon­gi­tu­di­nal phase-space di­ag­nos­tics. Beam com­mis­sion­ing ex­pe­ri­ence of the Tcav is re­ported in this paper. The cav­ity rf con­di­tion­ing and cal­i­bra­tion was per­formed. There is a hor­i­zon­tally bend­ing di­pole mag­net down­stream of the Tcav, which kicks beam in the ver­ti­cal plane. Beam image on a YAG screen down­stream of the Tcav and di­pole mag­net con­tains the sin­gle-shot in­for­ma­tion of the lon­gi­tu­di­nal phase-space of the photo-in­jec­tor beam. The first mea­sure­ments of the lon­gi­tu­di­nal phase-space of the com­pressed and non-com­pressed pho­toin­jec­tor beam are dis­cussed. Im­prove­ments of the mea­sure­ment res­o­lu­tion are planned. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB083  
About • paper received ※ 25 May 2021       paper accepted ※ 12 July 2021       issue date ※ 26 August 2021  
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THPAB106 Optimization of a High Bunch Charge ERL Injection Merger for PERLE emittance, linac, space-charge, booster 3983
 
  • B. Hounsell, M. Klein, C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  • S.A. Bogacz
    JLab, Newport News, Virginia, USA
  • C. Bruni, B. Hounsell, W. Kaabi
    Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
  • B. Hounsell, B.L. Militsyn, C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • B.L. Militsyn
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  
  De­liv­ery of high charge elec­tron bunches into the main loop of an ERL (en­ergy re­cov­ery linac) while pre­serv­ing the emit­tance is chal­leng­ing. This is be­cause at the typ­i­cal in­jec­tion mo­men­tum, space charge forces still have a sig­nif­i­cant ef­fect on the beam dy­nam­ics. In this work we con­sider the de­sign of the merger for PERLE, an ERL test fa­cil­ity to be based at IJ­CLab in France. Pre­vi­ous sim­u­la­tions have shown that the base­line DC gun based in­jec­tor can achieve the re­quired emit­tance at the booster linac exit. The qual­ity of the 500 pC bunches must then be pre­served with space charge through the merger at total beam en­ergy of 7 MeV keep­ing the emit­tance below 6 mm mrad. The beam dy­nam­ics in the merger were sim­u­lated using the code OPAL and op­ti­mised using a ge­netic al­go­rithm. Three pos­si­ble merger schemes were in­ves­ti­gated. The goal of the op­ti­mi­sa­tion was to min­imise the emit­tance growth while also achiev­ing the re­quired Twiss pa­ra­me­ters to match onto the spreader at the main linac exit. A three di­pole so­lu­tion is then ex­am­ined in more de­tail.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB106  
About • paper received ※ 19 May 2021       paper accepted ※ 16 July 2021       issue date ※ 02 September 2021  
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THPAB121 Plasma Muon Beam Cooling for HEP plasma, focusing, simulation, emittance 3999
 
  • M.A. Cummings, R.J. Abrams, R.P. Johnson, S.A. Kahn, T.J. Roberts
    Muons, Inc, Illinois, USA
  • V.S. Morozov, A.V. Sy
    JLab, Newport News, Virginia, USA
  • K. Yonehara
    Fermilab, Batavia, Illinois, USA
  
  Ion­iza­tion cool­ing has the po­ten­tial to shrink the phase space of a muon beam by a fac­tor of 106 within the muons’ short life­time (2.2 µs) be­cause the col­li­sion fre­quency in a cool­ing medium is ex­tremely high com­pared to con­ven­tional beam cool­ing meth­ods. It has been re­al­ized that ion­iza­tion cool­ing in­her­ently pro­duces a plasma of free elec­trons in­side the ab­sorber ma­te­r­ial, and this plasma can have an im­por­tant ef­fect on the muon beam. In par­tic­u­lar, under the right cir­cum­stances, it can both im­prove the rate of cool­ing and re­duce the equi­lib­rium emit­tance of the beam. This has the po­ten­tial to im­prove the per­for­mance of muon fa­cil­i­ties based on muon cool­ing; in par­tic­u­lar a fu­ture muon col­lider. We de­scribe how this pro­ject will in­te­grate Plasma muon beam cool­ing into both the basic He­li­cal Cool­ing Chan­nel (HCC) and ex­treme Para­met­ric-res­o­nance Ion­iza­tion Cool­ing (PIC) tech­niques. This po­ten­tially whole new ap­proach to muon cool­ing has ex­cit­ing prospects for sig­nif­i­cantly re­duced muon beam emit­tance.  
poster icon Poster THPAB121 [1.214 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB121  
About • paper received ※ 19 May 2021       paper accepted ※ 12 July 2021       issue date ※ 26 August 2021  
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THPAB138 FEbreak: A Comprehensive Diagnostic and Automated Conditioning Interface for Analysis of Breakdown and Dark Current Effects controls, FPGA, real-time, software 4027
 
  • M.E. Schneider, S.V. Baryshev
    Michigan State University, East Lansing, Michigan, USA
  • R.L. Fleming, D. Gorelov, J.W. Lewellen, E.I. Simakov
    LANL, Los Alamos, New Mexico, USA
  • E. Jevarjian
    MSU, East Lansing, Michigan, USA
  
  Funding: DE-AC02-06CH11357, No. DE-SC0018362, DE-NA-0003525, DE-AC52-06NA25396, LA-UR-21-20613
As the next gen­er­a­tion of ac­cel­er­a­tor tech­nol­ogy pushes to­wards being able to achieve higher and higher gra­di­ents there is a need to de­velop high-fre­quency struc­tures that can sup­port these fields *. The con­di­tion­ing process of the struc­tures and wave­guides to high gra­di­ent is a la­bor-in­ten­sive process, its length in­creases as the max­i­mum gra­di­ent is in­creased. This re­sults in the need to au­to­mate the con­di­tion­ing process. This au­toma­tion must allow for high ac­cu­racy cal­cu­la­tions of the break­down prob­a­bil­i­ties as­so­ci­ated with the con­di­tion­ing process which can be used to in­struct the con­di­tion­ing pro­ce­dure with­out the need for human in­ter­ven­tion. To au­to­mate the con­di­tion­ing process at LANL’s high gra­di­ent C-band ac­cel­er­a­tor test stand we de­vel­oped FEbreak that is a break­out prob­a­bil­ity and con­di­tion­ing au­toma­tion soft­ware that is a part of the FE­mas­ter se­ries **, ***, ****. FEbreak di­rectly in­ter­faces with the rest of FE­mas­ter to au­to­mate the data col­lec­tion and data pro­cess­ing to not only an­a­lyze the break­down prob­a­bil­ity but also the dark cur­rent ef­fects as­so­ci­ated with these high gra­di­ent struc­tures.
* E. I. Simakov Nuc. Inst. and Meth, in Phy. Research Section A: Acc. Spec, 907 221 (2019)
** E. Jevarjian arXiv:2009.13046
*** T. Y. Posos arXiv:2012.03578
**** M. Schneider arXiv:2012.10804
 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB138  
About • paper received ※ 18 May 2021       paper accepted ※ 02 July 2021       issue date ※ 23 August 2021  
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THPAB145 Cold Test of a Novel S-Band 1.6 Cell Photocathode RF Gun gun, coupling, cathode, simulation 4045
 
  • Zh.X. Tang, S.X. Dong, Y.J. Pei, B.F. Wei
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
  
  Funding: Work supported by National Natural Science Foundation of China(Grant No. 11805199 and U1832135) and Fundamental Research Funds for the Central Universities (Grant No. WK2310000072)
The pho­to­cath­ode RF gun is one of the most crit­i­cal com­po­nents for high qual­ity elec­tron beam sources. The asym­met­ric multi-pole field con­tributes to the trans­verse emit­tance growth and de­grades the beam qual­ity. In order to over­come the prob­lem, we pro­pose a novel ro­ta­tion­ally sym­met­ric 1.6 cell RF gun to con­struct the sym­met­ric field in this paper. The con­crete pro­posal is that a coax­ial cell cav­ity with a sym­met­ri­cal dis­tri­b­u­tion of four grooves is con­cate­nated to the pho­to­cath­ode end of the tra­di­tional 0.6 cell cav­ity to form the novel 0.6 cell cav­ity. Through the de­tailed de­sign study, the pro­file of the RF gun is op­ti­mized to im­prove the shunt im­ped­ance and mode sep­a­ra­tion and make the sur­face peak elec­tric field at the pho­to­cath­ode end. Con­sid­er­ing the fill­ing time, a cou­pling slot is de­signed to cou­ple input power into the RF gun. The RF cav­ity is ma­chined by nu­mer­i­cal con­trol ma­chine tool, and the tun­ing and low power RF mea­sure­ment are car­ried out. The ex­per­i­men­tal re­sults are con­sis­tent with the sim­u­la­tion re­sults. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB145  
About • paper received ※ 09 May 2021       paper accepted ※ 30 August 2021       issue date ※ 02 September 2021  
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THPAB146 Preliminary Study of Femtosecond Electron Source Based on THz Acceleration and Field Emission electron, FEM, cathode, gun 4048
 
  • Zh.X. Tang, G. Feng, B.F. Wei
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
  
  Funding: Work supported by National Natural Science Foundation of China (Grant No. U1832135 and 11805199) and Fundamental Research Funds for the Central Universities (Grant No. WK2310000072)
In this paper, we pro­pose a novel elec­tron gun based on THz ac­cel­er­a­tion and field emis­sion to gen­er­ate fem­tosec­ond elec­tron bunches. The field emis­sion cath­ode is placed in the cen­ter of the cav­ity, and the stand­ing wave field is es­tab­lished in the cav­ity to achieve the field emis­sion con­di­tions and ex­tract the elec­tron beam. Be­cause the pe­riod of THz band is about pi­cosec­ond, the fem­tosec­ond bunch is formed by con­trol­ling the field strength and the pulse width of the ex­tracted beam. We an­a­lyzed the fea­si­bil­ity of field emis­sion and the length of the pulse beam. The sur­face peak field in­ten­sity of the struc­ture of the cav­ity with dif­fer­ent emit­ters are sim­u­lated by CST soft­ware. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB146  
About • paper received ※ 09 May 2021       paper accepted ※ 18 August 2021       issue date ※ 02 September 2021  
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THPAB147 Preliminary Study of 500 MHz HOM-Free RF Cavity HOM, coupling, GUI, damping 4050
 
  • Zh.X. Tang
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
  
  Funding: Work supported by National Natural Science Foundation of China(Grant No. U1832135 and 11805199)}
In this paper, we study the mi­crowave char­ac­ter­is­tics of 500 MHz RF cav­ity, in­clud­ing the op­ti­miza­tion of cav­ity struc­ture, the sim­u­la­tion de­sign of high-or­der mode (HOM) ab­sorp­tion struc­ture and the de­sign of cou­pler. The cav­ity struc­ture is sim­u­lated by CST. The ab­sorp­tion wave­guide is de­signed and op­ti­mized. The cou­pler is de­signed. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB147  
About • paper received ※ 09 May 2021       paper accepted ※ 16 July 2021       issue date ※ 23 August 2021  
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THPAB153 Design, Construction and Tests of the Cooling System with a Cryocooler for Cavity Testing cryogenics, SRF, vacuum, simulation 4056
 
  • P. Pizzol, J.W. Lewellen, E.R. Olivas, E.I. Simakov, T. Tajima
    LANL, Los Alamos, New Mexico, USA
  
  Cryo­geni­cally cooled nor­mal-con­duct­ing cav­i­ties have shown higher gra­di­ents than those op­er­ated at room tem­per­a­ture. We are con­struct­ing a com­pact cool­ing sys­tem with a cry­ocooler to test C-band nor­mal-con­duct­ing cav­i­ties and 1.3 GHz su­per­con­duct­ing cav­i­ties. This paper de­scribes the de­sign, con­struc­tion, and cool­ing test re­sults as well as some low-power cav­ity Q mea­sure­ment re­sults.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB153  
About • paper received ※ 17 May 2021       paper accepted ※ 21 June 2021       issue date ※ 12 August 2021  
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THPAB156 Built-in Thermionic Electron Source for an SRF Linacs cathode, electron, gun, SRF 4062
 
  • I.V. Gonin, S. Kazakov, R.D. Kephart, T.N. Khabiboulline, T.H. Nicol, N. Solyak, J.C.T. Thangaraj, V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
  
  The de­sign of a thermionic elec­tron source con­nected di­rectly to a su­per­con­duct­ing cav­ity, the key part of an SRF gun, is de­scribed. The re­sults of beam dy­nam­ics op­ti­miza­tion are pre­sented which allow lack of beam cur­rent in­ter­cept­ing in the su­per­con­duct­ing cav­ity. The elec­tron source con­cept is pre­sented in­clud­ing the cath­ode-grid as­sem­bly, ther­mal in­su­la­tion of the cath­ode from the cav­ity, and the gun res­onator de­sign. The cav­ity ther­mal load caused by the gun is an­a­lyzed in­clud­ing the sta­tic heat load, black body ra­di­a­tion, back­ward elec­tron heat­ing, etc.  
poster icon Poster THPAB156 [0.670 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB156  
About • paper received ※ 19 May 2021       paper accepted ※ 12 July 2021       issue date ※ 28 August 2021  
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THPAB167 Technical Design of an RFQ Injector for the IsoDAR Cyclotron rfq, cyclotron, simulation, coupling 4075
 
  • H. Höltermann, D. Koser, B. Koubek, H. Podlech, U. Ratzinger, M. Schuett, M. Syha
    BEVATECH, Frankfurt, Germany
  • J.M. Conrad, J. Smolsky, L.H. Waites, D. Winklehner
    MIT, Cambridge, Massachusetts, USA
  
  For the Iso­DAR (Iso­tope De­cay-At-Rest) ex­per­i­ment, a high in­ten­sity (10 mA CW) pri­mary pro­ton beam is needed. To gen­er­ate this beam, H2+ is ac­cel­er­ated in a cy­clotron and stripped into pro­tons after ex­trac­tion. An RFQ, par­tially em­bed­ded in the cy­clotron yoke, will be used to bunch and ax­i­ally in­ject H2+ ions into the main ac­cel­er­a­tor. The strong RFQ bunch­ing ca­pa­bil­i­ties will be used to op­ti­mize the over­all in­jec­tion ef­fi­ciency. To keep the setup com­pact the dis­tance be­tween the ion source and RFQ can be kept very short as well. In this paper, we de­scribe the tech­ni­cal de­sign of the RFQ. We focus on two crit­i­cal as­pects: 1. The use of a split-coax­ial struc­ture, ne­ces­si­tated by the low fre­quency of 32.8 MHz (match­ing the cy­clotron RF) and the de­sired small tank di­am­e­ter; 2. The high cur­rent, CW op­er­a­tion, re­quir­ing a good cool­ing con­cept for the RFQ tank and vanes.  
poster icon Poster THPAB167 [2.162 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB167  
About • paper received ※ 14 May 2021       paper accepted ※ 27 July 2021       issue date ※ 22 August 2021  
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THPAB170 RF Deflector Design for Rapid Proton Therapy proton, simulation, polarization, quadrupole 4086
 
  • E.J.C. Snively, G.B. Bowden, V.A. Dolgashev, Z. Li, E.A. Nanni, D.T. Palmer, S.G. Tantawi
    SLAC, Menlo Park, California, USA
  
  Funding: This work is supported by US Department of Energy Contract No. DE-AC02-76SF00515.
Pen­cil beam scan­ning of charged par­ti­cle beams is a key tech­nol­ogy en­abling high dose rate can­cer ther­apy. The po­ten­tial ben­e­fits of high-speed dose de­liv­ery in­clude not only a re­duc­tion in total treat­ment time and im­prove­ments to mo­tion man­age­ment dur­ing treat­ment but also the pos­si­bil­ity of en­hanced healthy tis­sue spar­ing through the FLASH ef­fect, a promis­ing new treat­ment modal­ity. We pre­sent here the de­sign of an RF de­flec­tor op­er­at­ing at 2.856 GHz for the rapid steer­ing of 150 MeV pro­ton beams. The de­sign uti­lizes a TE11-like mode sup­ported by two posts pro­trud­ing into a pill­box geom­e­try to form an RF di­pole. This con­fig­u­ra­tion pro­vides a sig­nif­i­cant en­hance­ment to the ef­fi­ciency of the struc­ture, char­ac­ter­ized by a trans­verse shunt im­ped­ance of 68 MOhm/m, as com­pared to a con­ven­tional TM11 de­flec­tor. We dis­cuss sim­u­la­tions of the struc­ture per­for­mance for sev­eral op­er­at­ing con­fig­u­ra­tions in­clud­ing the ad­di­tion of a per­ma­nent mag­net quadru­pole to am­plify the RF-dri­ven de­flec­tion. In ad­di­tion to sim­u­la­tion stud­ies, we will pre­sent pre­lim­i­nary re­sults from a 3-cell pro­to­type fab­ri­cated using four cop­per slabs to ac­com­mo­date the non-ax­i­ally sym­met­ric cell geom­e­try. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB170  
About • paper received ※ 19 May 2021       paper accepted ※ 14 July 2021       issue date ※ 28 August 2021  
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THPAB173 Fundamental Study on Electromagnetic Characteristics of Half-Wave Resonator for 200 MeV Energy Upgrade of KOMAC Proton Linac simulation, linac, proton, SRF 4098
 
  • J.J. Dang, Y.-S. Cho, H.S. Kim, H.-J. Kwon, S. Lee
    Korea Atomic Energy Research Institute (KAERI), Gyeongbuk, Republic of Korea
  
  Funding: This work has been supported through KOMAC operation fund of KAERI by the Korea government (MSIT).
A su­per­con­duct­ing linac has been de­vel­oped at KOrea Multi-pur­pose Ac­cel­er­a­tor Com­plex (KOMAC). A goal of the SRF linac is to in­crease pro­ton beam en­ergy from 100 MeV to 200 MeV. 350 MHz medium beta half-wave res­onator (HWR) should pro­vide 3.6 MV ac­cel­er­at­ing volt­age to achieve the en­ergy up­grade. An elec­tro­mag­netic (EM) analy­sis on the para­met­ri­cally de­signed HWR cav­ity was con­ducted. The cav­ity de­sign was op­ti­mized to re­duce a peak elec­tric field and a peak mag­netic field while sat­is­fy­ing the re­quired ac­er­at­ing volt­age. In ad­di­tion, a me­chan­i­cal-EM cou­pled sim­u­la­tion was con­ducted to es­ti­mate a he­lium pres­sure sen­si­tiv­ity. Also, Lorentz force de­tun­ing was sim­u­lated. The de­sign is being op­ti­mized to min­i­mize the fre­quency de­tun­ing due to the he­lium pres­sure and Lorentz force. 		 
poster icon Poster THPAB173 [0.800 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB173  
About • paper received ※ 19 May 2021       paper accepted ※ 21 June 2021       issue date ※ 22 August 2021  
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THPAB183 New Longitudinal Beam Production Methods in the CERN Proton Synchrotron Booster space-charge, emittance, proton, resonance 4130
 
  • S.C.P. Albright, F. Antoniou, F. Asvesta, H. Bartosik, C. Bracco, E. Renner
    CERN, Meyrin, Switzerland
  • E. Renner
    TU Vienna, Wien, Austria
  
  As part of the LHC In­jec­tors Up­grade (LIU) pro­ject, sig­nif­i­cant im­prove­ments were made to the CERN Pro­ton Syn­chro­tron Booster (PSB) dur­ing the 2019/2020 long shut­down, in­clud­ing a new Finemet-based wide­band RF sys­tem, ren­o­vated lon­gi­tu­di­nal beam con­trol, and a new mag­netic cycle. To meet the re­quire­ments of the di­verse ex­per­i­men­tal pro­gram, the PSB pro­vides beams with in­ten­si­ties span­ning three or­ders of mag­ni­tude and a large range of lon­gi­tu­di­nal emit­tances. To max­i­mize the bright­ness, in par­tic­u­lar for the LHC beams, the volt­ages at low en­ergy are de­signed to re­duce the im­pact of trans­verse space charge using a sec­ond RF har­monic in bunch length­en­ing mode. At high en­er­gies, the risk of lon­gi­tu­di­nal mi­crowave in­sta­bil­ity is avoided by op­ti­miz­ing the lon­gi­tu­di­nal dis­tri­b­u­tion to raise the in­sta­bil­ity thresh­old. RF phase noise is ap­plied to pro­vide con­trolled lon­gi­tu­di­nal emit­tance blow-up and to shape the lon­gi­tu­di­nal dis­tri­b­u­tion. This paper dis­cusses the de­sign of the RF func­tions used to meet the beam spec­i­fi­ca­tions, whilst en­sur­ing lon­gi­tu­di­nal sta­bil­ity.  
poster icon Poster THPAB183 [6.692 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB183  
About • paper received ※ 18 May 2021       paper accepted ※ 22 July 2021       issue date ※ 01 September 2021  
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THPAB187 Determination of Required Tolerances and Stop Band Width for Cells Manufacturing and Tuning in Compensated High Energy Accelerating Structures coupling, linac, hadron, factory 4139
 
  • I.V. Rybakov, V.V. Paramonov
    RAS/INR, Moscow, Russia
  
  The re­quired value of the spread for ac­cel­er­at­ing field dis­tri­b­u­tion comes from the beam dy­nam­ics con­di­tions and for cav­i­ties in high en­ergy hadron linacs is ~1%. The stan­dard de­vi­a­tion of the ac­cel­er­at­ing field dis­tri­b­u­tion de­pends on the spread in fre­quen­cies of ac­cel­er­at­ing and cou­pling cells, stop band­width and de­vi­a­tions in cou­pling co­ef­fi­cients. The de­vi­a­tions in fre­quen­cies for ac­cel­er­at­ing, cou­pling cells, cou­pling co­ef­fi­cients, are di­rectly re­lated to tol­er­ances man­u­fac­tur­ing tol­er­ances for cells. The stop band­width should be ad­justed with cell tun­ing. Re­la­tions be­tween the stan­dard de­vi­a­tion of field dis­tri­b­u­tion and de­vi­a­tions in cells pa­ra­me­ters* are known. To­gether with the re­la­tion be­tween de­vi­a­tions in cells di­men­sions and cells pa­ra­me­ters** rec­om­men­da­tions for cells man­u­fac­tur­ing tol­er­ances could be ob­tained. In re­la­tion to the cou­pling co­ef­fi­cient of com­pen­sated ac­cel­er­at­ing struc­tures (ACS, SCS, CDS, DAW) for high-en­ergy parts of linacs some rec­om­men­da­tions for the de­ter­mi­na­tion of op­ti­mal man­u­fac­tur­ing tol­er­ances and ac­cept­able stop­band are pre­sented.
* V.F. Vikulov and V.E. Kalyuzhny // Tech. Phys., v. 50, 1980, pp. 773-779
** I.V. Rybakov, V.V. Paramonov, A.K. Skassyrskaya // Proc. RuPAC 2016, pp. 291-293 		 
poster icon Poster THPAB187 [0.649 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB187  
About • paper received ※ 18 May 2021       paper accepted ※ 25 June 2021       issue date ※ 11 August 2021  
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THPAB200 Cavity Control Modelling for SPS-to-LHC Beam Transfer Studies controls, beam-loading, simulation, injection 4168
 
  • L.E. Medina Medrano, T. Argyropoulos, P. Baudrenghien, H. Timko
    CERN, Geneva, Switzerland
  
  Funding: Research supported by the HL-LHC project.
To ac­cu­rately sim­u­late in­jec­tion losses in the LHC and the High-Lu­mi­nos­ity LHC era, a re­al­is­tic beam dis­tri­b­u­tion model at SPS ex­trac­tion is needed. To achieve this, the beam-load­ing com­pen­sa­tion by the SPS cav­ity con­troller has to be in­cluded, as it mod­u­lates the bunch po­si­tions with re­spect to the rf buck­ets. This dy­namic cav­ity con­trol model also al­lows gen­er­at­ing a more re­al­is­tic beam halo, from which the LHC in­jec­tion losses will mainly orig­i­nate. In this paper, the im­ple­men­ta­tion of the pre­sent SPS cav­ity con­troller in CERN’s Beam Lon­gi­tu­di­nal Dy­nam­ics par­ti­cle track­ing code is de­scribed. Just like in the ma­chine, the feed­back and feed­for­ward con­trols are in­cluded in the sim­u­la­tion model, as well as the gen­er­a­tor-beam-cav­ity in­ter­ac­tion. Bench­mark­ing against mea­sure­ments of the gen­er­ated beam dis­tri­b­u­tions at SPS ex­trac­tion are pre­sented. 		 
poster icon Poster THPAB200 [4.164 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB200  
About • paper received ※ 18 May 2021       paper accepted ※ 27 July 2021       issue date ※ 15 August 2021  
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THPAB219 Beam Dynamics in Coherent Electron Cooling Accelerator electron, simulation, linac, emittance 4216
 
  • Y.C. Jing, V. Litvinenko, I. Petrushina, I. Pinayev, K. Shih, Y.H. Wu
    BNL, Upton, New York, USA
  • V. Litvinenko
    Stony Brook University, Stony Brook, USA
  • I. Petrushina, Y.H. Wu
    SUNY SB, Stony Brook, New York, USA
  • K. Shih
    SBU, Stony Brook, New York, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Co­her­ent elec­tron Cool­ing (CeC) has the po­ten­tial to sub­stan­tially re­duce the cool­ing time of the high-en­ergy hadrons and hence to boost lu­mi­nos­ity in high-in­ten­sity hadron-hadron and elec­tron-hadron col­lid­ers. Re­cent de­vel­op­ment in CeC cool­ing the­ory re­quires the ac­cel­er­a­tor to de­liver high-qual­ity elec­tron bunches with low beam noise. In this paper, we pre­sent our de­sign of the CeC ac­cel­er­a­tor to achieve the elec­tron beam re­quire­ments and com­pare our find­ings with the ex­per­i­men­tal ob­ser­va­tions. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB219  
About • paper received ※ 27 May 2021       paper accepted ※ 27 July 2021       issue date ※ 20 August 2021  
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THPAB220 Multibunch Studies for LCLS-II High Energy Upgrade dipole, linac, emittance, HOM 4219
 
  • R.J. England, K.L.F. Bane, Z. Li, T.O. Raubenheimer, M.D. Woodley
    SLAC, Menlo Park, California, USA
  • M. Borland
    ANL, Lemont, Illinois, USA
  • A. Lunin
    Fermilab, Batavia, Illinois, USA
  
  Funding: The work is supported in part by DOE Contract No. DE-AC02-76SF00515.
The Linac Co­her­ent Light Source (LCLS) X-ray free-elec­tron laser at SLAC is being up­graded to LCLS-II with a su­per­con­duct­ing linac and 1 MHz bunch rep­e­ti­tion rate. The pro­posed high-en­ergy up­grade (LCLS-II-HE) will in­crease the beam en­ergy from 4 to 8 GeV, ex­tend­ing the reach of ac­ces­si­ble X-ray pho­ton en­er­gies. With the in­creased rep­e­ti­tion rate and longer linac of LCLS-II-HE, multi-bunch ef­fects are of greater con­cern. We use re­cently in­tro­duced ca­pa­bil­i­ties in the beam trans­port code EL­E­GANT to study di­pole and mono­pole beam breakup ef­fects for LCLS-II HE beam pa­ra­me­ters. The re­sults in­di­cate that res­o­nant di­pole kicks have steady-state set­tle times on the order of 500 bunches or less and ap­pear man­age­able. We also con­sider a sta­tis­ti­cal vari­a­tion of the cav­ity fre­quen­cies and trans­verse off­sets of cav­i­ties and quadrupoles. Res­o­nant emit­tance growth dri­ven by mono­pole kicks is found to be dis­rupted by fre­quency vari­a­tion be­tween cav­i­ties. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB220  
About • paper received ※ 19 May 2021       paper accepted ※ 15 July 2021       issue date ※ 16 August 2021  
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THPAB221 Multi-Objective Optimization with ACE3P and IMPACT cathode, simulation, lattice, interface 4223
 
  • D.A. Bizzozero, J. Qiang
    LBNL, Berkeley, California, USA
  • L. Ge, Z. Li, C.-K. Ng, L. Xiao
    SLAC, Menlo Park, California, USA
  
  Funding: This work is supported by the Director of the Office of Science of the US Department of Energy under contracts DE-AC02-05-CH11231 and DE-AC02-76-SF00515.
Photo in­jec­tor de­sign is an im­por­tant con­sid­er­a­tion in the con­struc­tion of next-gen­er­a­tion ac­cel­er­a­tors. In cur­rent in­jec­tor op­ti­miza­tion, com­po­nents (e.g. RF cav­i­ties) are in­di­vid­u­ally shape-op­ti­mized for per­for­mance sub­ject to re­quire­ments such as peak sur­face field, shunt im­ped­ance, and res­o­nant fre­quency. Once these com­po­nent shapes are de­ter­mined, beam dy­nam­ics sim­u­la­tions op­ti­mize the in­jec­tor lat­tice by ad­just­ing pa­ra­me­ters such as the am­pli­tude and phase of the dri­ving fields. How­ever, this form of beam dy­nam­ics op­ti­miza­tion is re­stricted by the fixed geom­e­try and field pro­file of the com­po­nents. To op­ti­mize ac­cel­er­a­tor de­sign more gen­er­ally, a cou­pled op­ti­miza­tion of the cav­ity shape and beam pa­ra­me­ters is re­quired. For this cou­pled op­ti­miza­tion prob­lem, we have cre­ated an in­te­grated ACE3P-IM­PACT work­flow. Within this work­flow, com­po­nent geome­tries are ad­justed, field modes are com­puted with Omega3P (a mod­ule in the ACE3P suite), and beam dy­nam­ics are sim­u­lated with IM­PACT-T. This work­flow is en­cap­su­lated into a multi-ob­jec­tive op­ti­miza­tion al­go­rithm using the DEAP* and libEnsem­ble** Python li­braries to yield a Pareto-op­ti­mal set of so­lu­tions for a sim­ple in­jec­tor model.
* F.-A. Fortin et al, DEAP: Evolutionary Algorithms Made Easy, J Mach Learn Res, 13, 2171-2175, July 2012
** S. Hudson et al, libEnsemble User Manual, Argonne National Laboratory, Rev 0.7.1, 2020 		 
poster icon Poster THPAB221 [1.842 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB221  
About • paper received ※ 19 May 2021       paper accepted ※ 02 August 2021       issue date ※ 26 August 2021  
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THPAB244 Design of Interdigital H-Mode Re-Buncher at KoBRA Beamline bunching, heavy-ion, impedance, simulation 4285
 
  • Y. Lee, E.-S. Kim
    KUS, Sejong, Republic of Korea
  
  KOrea Broad ac­cep­tance Re­coil spec­trom­e­ter & Ap­pa­ra­tus (KOBRA) is an ex­per­i­men­tal fa­cil­ity for low en­ergy nu­clear physics in the heavy ion ac­cel­er­a­tor com­plex RAON. Two re-buncher sys­tems at KOBRA beam­line are re­quired to lon­gi­tu­di­nally focus the 40Ar9+ with 27MeV/u. The nor­mal con­duct­ing IH res­onator with seven-gap as the re-buncher struc­ture was cho­sen be­cause of the re­duc­tion in the risk of par­tic­u­late con­t­a­m­i­na­tion and total power con­sump­tion. In this paper, the de­tailed de­sign re­sults of the 162.5 MHz IH re-buncher cav­ity will be pre­sented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB244  
About • paper received ※ 19 May 2021       paper accepted ※ 27 July 2021       issue date ※ 13 August 2021  
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THPAB268 Hierarchical Intelligent Real-Time Optimal Control for LLRF Using Time Series Machine Learning Methods and Transfer Learning controls, LLRF, network, simulation 4329
 
  • R. Pirayesh, S. Biedron
    UNM-ME, Albuquerque, New Mexico, USA
  • S. Biedron, J.A. Diaz Cruz, M. Martínez-Ramón
    UNM-ECE, Albuquerque, USA
  • J.A. Diaz Cruz
    SLAC, Menlo Park, California, USA
  
  Funding: supported by DOE, Office of Science, Office of High Energy Physics, under award number DE-SC0019468, Contract No. DE-AC02-76SF00515, also supported Office of Basic Energy Sciences. ALCF, Element Aero
Ma­chine learn­ing (ML) has re­cently been ap­plied to Low-level RF (LLRF) con­trol sys­tems to keep the volt­age and phase of Su­per­con­duct­ing Ra­diofre­quency (SRF) cav­i­ties sta­ble within 0.01 de­gree in phase and 0.01% am­pli­tude as con­straints. Model pre­dic­tive con­trol (MPC) uses an op­ti­miza­tion al­go­rithm of­fline to min­i­mize a cost func­tion with con­straints on the states and con­trol input. The sur­ro­gate model op­ti­mally con­trols the cav­i­ties on­line. Time se­ries deep ML struc­tures in­clud­ing re­cur­rent neural net­work (RNN) and long short-term mem­ory (LSTM) can model the con­trol input of MPC and dy­nam­ics of LLRF as a sur­ro­gate model. When the pre­dicted states di­verge from the mea­sured states more than a thresh­old at each time step, the states’ mea­sure­ments from the cav­ity fine-tune the sur­ro­gate model with trans­fer learn­ing. MPC does the op­ti­miza­tion of­fline again with the up­dated sur­ro­gate model, and, next, trans­fer learn­ing fine-tunes the sur­ro­gate model with the new data from the op­ti­mal con­trol in­puts. The sur­ro­gate model pro­vides us with a com­pu­ta­tion­ally faster and ac­cu­rate mod­el­ing of MPC and LLRF, which in turn re­sults in a more sta­ble con­trol sys­tem.
Machine learning, Surrogate model, control, LLRF, MPC, Transfer learning 		 
poster icon Poster THPAB268 [0.377 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB268  
About • paper received ※ 16 May 2021       paper accepted ※ 13 July 2021       issue date ※ 28 August 2021  
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THPAB271 JLAB LLRF 3.0 Development and Tests LLRF, controls, FPGA, cryomodule 4340
 
  • T.E. Plawski, R. Bachimanchi, S. Higgins, C. Hovater, J. Latshaw, C.I. Mounts, D.J. Seidman, J. Yan
    JLab, Newport News, Virginia, USA
  
  The Jef­fer­son Lab LLRF 3.0 sys­tem is being de­vel­oped to re­place legacy LLRF sys­tems in the CEBAF ac­cel­er­a­tor. The new de­sign builds upon 25 years of de­sign and op­er­a­tional RF con­trol ex­pe­ri­ence, and our re­cent col­lab­o­ra­tion in the de­sign of the LCLSII LLRF sys­tem. The new cav­ity con­trol al­go­rithm is a fully func­tional phase and am­pli­tude locked Self Ex­cit­ing Loop (SEL). This paper dis­cusses the progress of the LLRF 3.0 hard­ware de­sign, FPGA firmware de­vel­op­ment, User Data­gram Pro­to­col (UDP) op­er­a­tion, and re­cent LLRF 3.0 sys­tem tests on the CEBAF Booster cry­omod­ule in the Up­grade In­jec­tor Test Fa­cil­ity (UITF).  
poster icon Poster THPAB271 [1.940 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB271  
About • paper received ※ 14 May 2021       paper accepted ※ 06 July 2021       issue date ※ 11 August 2021  
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THPAB272 Validation of Two Re-Buncher Cavities under High Beam Loading for LIPAc LLRF, beam-loading, operation, MEBT 4343
 
  • D. Gavela, I. Podadera, F. Toral
    CIEMAT, Madrid, Spain
  • I. Moya
    Fusion for Energy, Garching, Germany
  • F. Scantamburlo
    IFMIF/EVEDA, Rokkasho, Japan
  
  Funding: Work partially supported by the Spanish Ministry of Science and Innovation under project AIC-A-2011-0654 and FIS2013-40860-R
Two re-buncher cav­i­ties were in­stalled at the Medium En­ergy Beam Trans­port line of the LIPAc ac­cel­er­a­tor, presently being com­mis­sioned at Rokkasho (Japan). They are IH-type cav­i­ties with five gaps pro­vid­ing an ef­fec­tive volt­age of 350 kV at 175 MHz for a nom­i­nal op­er­a­tion of 125 mA CW deuterons at 5 MeV. After full con­di­tion­ing and beam­line in­te­gra­tion in Eu­rope, the cav­i­ties were in­stalled in the ac­cel­er­a­tor with spe­cial care given to the align­ment with re­spect to the rest of the com­po­nents. The RF line, cool­ing cir­cuits, and in­stru­men­ta­tion were also mounted. The cav­i­ties were op­er­ated with an FPGA-based LLRF sys­tem. A re-con­di­tion­ing of the cav­i­ties was per­formed in the first place, fol­lowed by tests with a pulsed beam with in­creas­ing cur­rents. A max­i­mum pulsed beam cur­rent of 100 mA was reached while op­er­at­ing the buncher cav­i­ties, under which they reached volt­ages up to 340 kV and 260 kV re­spec­tively. As ex­pected, the beam load­ing was sig­nif­i­cant, lead­ing to a se­ries of dif­fi­cul­ties and re­quired strate­gies for a good op­er­a­tion that are dis­cussed in this paper. The ef­fect on the beam dy­nam­ics, mea­sured by beam po­si­tion mon­i­tors down­stream of the bunch­ers is also dis­cussed. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB272  
About • paper received ※ 19 May 2021       paper accepted ※ 02 September 2021       issue date ※ 02 September 2021  
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THPAB287 Providing Computing Power for High Level Controllers in MicroTCA-based LLRF Systems via PCI Express Extension controls, LLRF, software, Ethernet 4363
 
  • P. Nonn, A. Eichler, S. Pfeiffer, H. Schlarb, J.H.K. Timm
    DESY, Hamburg, Germany
  
  It is pos­si­ble to con­nect the PCIe bus of a high per­for­mance com­puter to a Mi­croTCA crate. This al­lows the soft­ware on the com­puter to com­mu­ni­cate with the mod­ules in the crate, as if they were pe­riph­er­als of the com­puter. This ar­ti­cle will dis­cuss the use of this fea­ture in re­spect to ac­cel­er­a­tor con­trol with a focus on High Level Con­trollers.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB287  
About • paper received ※ 19 May 2021       paper accepted ※ 26 July 2021       issue date ※ 26 August 2021  
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THPAB296 The Spallation Neutron Source Normal Conducting Linac RF System Design for the Proton Power Upgrade Project DTL, GUI, klystron, linac 4383
 
  • J.S. Moss, M.T. Crofford, S.W. Lee, G.D. Toby
    ORNL, Oak Ridge, Tennessee, USA
  • M.E. Middendorf
    ORNL RAD, Oak Ridge, Tennessee, USA
  
  Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under contract number DE-AC05-00OR22725.
The Pro­ton Power Up­grade (PPU) pro­ject at the Spal­la­tion Neu­tron Source will dou­ble the avail­able pro­ton beam power from 1.4 to 2.8 MW by in­creas­ing the beam en­ergy from 1.0 to 1.3 GeV and the beam cur­rent from 26 to 38 mA. The in­crease in beam cur­rent re­sulted in the need to re­design the ex­ist­ing nor­mal con­duct­ing linac (NCL) RF Sys­tems. High-power test­ing of the ex­ist­ing NCL RF Sys­tems con­fig­ured to ac­cel­er­ate PPU-level beam pro­vided the data used to make the final de­sign de­ci­sions. This paper de­scribes the de­vel­op­ment and ex­e­cu­tion of those in-situ tests and the sub­se­quent re­sults. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB296  
About • paper received ※ 17 May 2021       paper accepted ※ 22 July 2021       issue date ※ 18 August 2021  
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THPAB317 Experiment and Simulation Study on the Capture and Acceleration Process of XiPAF Synchrotron acceleration, synchrotron, experiment, proton 4409
 
  • Y. Li, X. Guan, X.Y. Liu, M.W. Wang, X.W. Wang, Q.Z. Xing, Y. Yang, H.J. Yao, W.B. Ye, S.X. Zheng
    TUB, Beijing, People’s Republic of China
  • W.L. Liu, D. Wang, Z.M. Wang, Y. Yang, M.T. Zhao
    NINT, Shannxi, People’s Republic of China
  
  The beam com­mis­sion­ing of the cap­ture and ac­cel­er­a­tion process on the XiPAF (Xi’an 200MeV Pro­ton Ap­pli­ca­tion Fa­cil­ity) syn­chro­tron has been car­ried out. The ef­fi­ciency of the ex­per­i­ment re­sults has been com­pared with the sim­u­la­tion re­sults. At pre­sent, the ef­fi­ciency of the cap­ture process with sin­gle-har­monic is about 73%, and the ac­cel­er­a­tion ef­fi­ciency is about 82%, and the sim­u­la­tion re­sults are 77% and 96% with­out space charge ef­fect, re­spec­tively. In order to im­prove ef­fi­ciency, dual-har­monic was used dur­ing the cap­ture and ac­cel­er­a­tion process. Dur­ing the ex­per­i­ment, the cap­ture ef­fi­ciency was in­creased by 5%, and the ac­cel­er­a­tion ef­fi­ciency was in­creased by 4%. The cap­ture ef­fi­ciency de­creases with the in­crease of the max­i­mum RF volt­ages. We an­a­lyzed the rea­sons for the de­crease in cap­ture ef­fi­ciency. In the next step, fur­ther ver­i­fi­ca­tion will be car­ried out through ex­per­i­ments under dif­fer­ent con­di­tions.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB317  
About • paper received ※ 19 May 2021       paper accepted ※ 08 July 2021       issue date ※ 19 August 2021  
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THPAB320 ALD-Based NbTiN Studies for SIS R&D site, plasma, SRF, niobium 4420
 
  • I. González Díaz-Palacio, R.H. Blick, R. Zierold
    University of Hamburg, Hamburg, Germany
  • W. Hillert, M. Wenskat
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  
  Su­per­con­duc­tor-In­su­la­tor-Su­per­con­duc­tor mul­ti­lay­ers im­prove the per­for­mance of SRF cav­i­ties pro­vid­ing mag­netic screen­ing of the bulk cav­ity and lower sur­face re­sis­tance. In this frame­work NbTiN mix­tures stand as a po­ten­tial ma­te­r­ial of in­ter­est. Atomic layer de­po­si­tion (ALD) al­lows for uni­form coat­ing of com­plex geome­tries and en­ables tun­ing of the sto­i­chiom­e­try and pre­cise thick­ness con­trol in sub-nm range. In this talk, we re­port about NbTiN thin films de­posited by plasma-en­hanced ALD on in­su­lat­ing AlN buffer layer. The de­po­si­tion process has been op­ti­mized by study­ing the su­per­con­duct­ing elec­tri­cal prop­er­ties of the films. Post-de­po­si­tion ther­mal an­neal­ing stud­ies with vary­ing tem­per­a­tures, an­neal­ing times, and gas at­mos­pheres have been per­formed to fur­ther im­prove the thin film qual­ity and the su­per­con­duct­ing prop­er­ties. Our ex­per­i­men­tal stud­ies show an in­crease in Tc by 87.5% after ther­mal an­neal­ing and a max­i­mum Tc of 13.9 K has been achieved for NbTiN of 23 nm thick­ness. Fu­ture steps in­clude lat­tice char­ac­ter­i­za­tion, using XRR/XRD/EBSD/PALS, and SRF mea­sure­ments to ob­tain Hc1 and the su­per­con­duct­ing gap.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB320  
About • paper received ※ 24 May 2021       paper accepted ※ 23 July 2021       issue date ※ 26 August 2021  
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THPAB322 Transient Beam Loading in the CBETA Multi-Turn ERL linac, beam-loading, operation, SRF 4422
 
  • N. Banerjee
    Enrico Fermi Institute, University of Chicago, Chicago, Illinois, USA
  • G.H. Hoffstaetter
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Funding: This work was supported by NSF Grant No. DMR0807731, DOE Award No. DE-SC0012704, and NYSERDA Agreement No. 102192.
The Cor­nell-BNL ERL Test Ac­cel­er­a­tor (CBETA) is the first su­per­con­duct­ing multi-turn ERL that has been com­mis­sioned at Cor­nell Uni­ver­sity in a low cur­rent mode. In this paper, we first dis­cuss a new model of beam load­ing which is valid for the low in­jec­tion en­er­gies used in CBETA. Using this model, we ex­plore the ef­fect of bunch pat­terns, beam turn-on, and turn-off tran­sients on the fun­da­men­tal mode of the 7-cell SRF cav­i­ties used in the main linac. In par­tic­u­lar, we ex­am­ine the op­er­a­tional con­straints on the rf sys­tem at the de­sign cur­rent of 40 mA. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB322  
About • paper received ※ 20 May 2021       paper accepted ※ 29 July 2021       issue date ※ 26 August 2021  
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THPAB336 Novel Magnetron Operation and Control Methods for Superconducting RF Accelerators controls, injection, operation, SRF 4442
 
  • G.M. Kazakevich, R.P. Johnson
    Muons, Inc, Illinois, USA
  • T.N. Khabiboulline, G.V. Romanov, V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
  
  High power mag­netrons de­signed and op­ti­mized for in­dus­trial heat­ing, being in­jec­tion-locked, have been sug­gested to power su­per­con­duct­ing RF cav­i­ties for ac­cel­er­a­tors due to lower cost and higher ef­fi­ciency. How­ever, stan­dard op­er­a­tion meth­ods do not pro­vide high ef­fi­ciency with wide­band con­trol sup­press­ing mi­cro­phon­ics. We have de­vel­oped and ex­per­i­men­tally ver­i­fied novel meth­ods of op­er­at­ing and con­trol­ling the mag­netron that pro­vide sta­ble RF gen­er­a­tion with higher ef­fi­ciency and lower noise than other RF sources. By our method the mag­netrons op­er­ate with the anode volt­age no­tably lower than the self-ex­ci­ta­tion thresh­old im­prov­ing its per­for­mance. This is also a promis­ing way to in­crease tube re­li­a­bil­ity and longevity. A mag­netron op­er­at­ing with the anode volt­age lower than the self-ex­ci­ta­tion thresh­old, in so-called stim­u­lated co­her­ent gen­er­a­tion mode has spe­cial ad­van­tage for pulse op­er­a­tion with a gated in­jec­tion-lock­ing sig­nal. This elim­i­nates the need for ex­pen­sive pulsed HV mod­u­la­tors and ad­di­tion­ally in­creases the mag­netron RF source ef­fi­ciency due to ab­sence of losses in HV mod­u­la­tors.  
poster icon Poster THPAB336 [0.960 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB336  
About • paper received ※ 15 May 2021       paper accepted ※ 08 July 2021       issue date ※ 18 August 2021  
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THPAB337 Resonance Control System for the PIP-II IT HWR Cryomodule controls, feedback, cryomodule, resonance 4446
 
  • P. Varghese, B.E. Chase, P.M. Hanlet, H. Maniar, D.J. Nicklaus, S. Sankar Raman
    Fermilab, Batavia, Illinois, USA
  • L.R. Doolittle, S. Paiagua, C. Serrano
    LBNL, Berkeley, California, USA
  
  The HWR (half-wave-res­onator) cry­omod­ule is the first one in the su­per­con­duct­ing sec­tion of the PIP-II LINAC pro­ject at Fer­mi­lab. PIP-II IT is a test fa­cil­ity for the pro­ject where the in­jec­tor, warm front-end, and the first two su­per­con­duct­ing cry­omod­ules are being tested. The HWR cry­omod­ule com­prises 8 cav­i­ties op­er­at­ing at a fre­quency of 162.5 MHz and ac­cel­er­at­ing beam up to 10 MeV. Res­o­nance con­trol of the cav­i­ties is per­formed with a pneu­mat­i­cally op­er­ated slow tuner which com­presses the cav­ity at the beam ports. He­lium gas pres­sure in a bel­lows mounted to an end wall of the cav­ity is con­trolled by two so­le­noid valves, one on the pres­sure side and one on the vac­uum side. The res­o­nant fre­quency of the cav­ity can be con­trolled in one of two modes. A pres­sure feed­back con­trol loop can hold the cav­ity tuner pres­sure at a fixed value for the de­sired res­o­nant fre­quency. Al­ter­nately, the feed­back loop can reg­u­late the cav­ity tuner pres­sure to bring the RF de­tun­ing error to zero. The res­o­nance con­troller is in­te­grated into the LLRF con­trol sys­tem for the cry­omod­ule. The con­trol sys­tem de­sign and per­for­mance of the res­o­nance con­trol sys­tem are de­scribed in this paper.  
poster icon Poster THPAB337 [4.426 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB337  
About • paper received ※ 12 May 2021       paper accepted ※ 26 July 2021       issue date ※ 15 August 2021  
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THPAB338 Performance of the LLRF System for the Fermilab PIP-II Injector Test controls, LLRF, resonance, cryomodule 4450
 
  • P. Varghese, B.E. Chase, P.M. Hanlet, H. Maniar, D.J. Nicklaus
    Fermilab, Batavia, Illinois, USA
  • L.R. Doolittle, C. Serrano
    LBNL, Berkeley, California, USA
  
  PIP-II IT is a test fa­cil­ity for the PIP-II pro­ject where the in­jec­tor, warm front-end, and the first two su­per­con­duct­ing cry­omod­ules are being tested. The 8-cav­ity half-wave-res­onator (HWR) cry­omod­ule op­er­at­ing at 162.5 MHz is fol­lowed by the 8-cav­ity sin­gle-spoke res­onator(SSR1) cry­omod­ule op­er­at­ing at 325 MHz. The LLRF sys­tems for both cry­omod­ules are based on a com­mon SOC FPGA-based hard­ware plat­form. The res­o­nance con­trol sys­tems for the two cry­omod­ules are quite dif­fer­ent, the first being a pneu­matic sys­tem based on he­lium pres­sure and the lat­ter a piezo/step­per motor type con­trol. The data ac­qui­si­tion and con­trol sys­tem can sup­port both CW and Pulsed mode op­er­a­tions. Beam load­ing com­pen­sa­tion is avail­able which can be used for both man­ual/au­to­matic con­trol in the LLRF sys­tem. The user in­ter­faces in­clude EPICS, Lab­view, and ACNET. Test­ing of the RF sys­tem has pro­gressed to the point of being ready for a 2 mA beam to be ac­cel­er­ated to 25 MeV. The de­sign and per­for­mance of the field con­trol and res­o­nance con­trol sys­tem op­er­a­tion with beam are pre­sented in this paper.  
poster icon Poster THPAB338 [5.482 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB338  
About • paper received ※ 13 May 2021       paper accepted ※ 27 July 2021       issue date ※ 19 August 2021  
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THPAB343 Test Results of the Prototype SSR1 Cryomodule for PIP-II at Fermilab cryomodule, SRF, vacuum, focusing 4461
 
  • D. Passarelli, J. Bernardini, C. Boffo, B.M. Hanna, S. Kazakov, T.N. Khabiboulline, A. Lunin, J.P. Ozelis, M. Parise, Y.M. Pischalnikov, V. Roger, B. Squires, A.I. Sukhanov, G. Wu, V.P. Yakovlev, S. Zorzetti
    Fermilab, Batavia, Illinois, USA
  • C. Contreras-Martinez
    FRIB, East Lansing, Michigan, USA
  
  Funding: Work supported by Fermi Research Alliance, LLC under Contract No. DEAC02- 07CH11359 with the United States Department of Energy
A pro­to­type cry­omod­ule con­tain­ing eight Sin­gle Spoke Res­onators type-1 (SSR1) op­er­at­ing at 325 MHz and four su­per­con­duct­ing fo­cus­ing lenses has been suc­cess­fully as­sem­bled and cold tested in the frame­work of PIP-II pro­ject at Fer­mi­lab. The per­for­mance of cav­i­ties and fo­cus­ing lenses along with test re­sults of other cry­omod­ule’s key pa­ra­me­ters are pre­sented in this con­tri­bu­tion. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB343  
About • paper received ※ 20 May 2021       paper accepted ※ 08 August 2021       issue date ※ 26 August 2021  
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THPAB347 Status of Sirius Storage Ring RF System operation, storage-ring, MMI, controls 4470
 
  • A.P.B. Lima, D. Daminelli, R.H.A. Farias, F.K.G. Hoshino, F.S. Oliveira, R.R.C. Santos, M.H. Wallner
    LNLS, Campinas, Brazil
  
  The de­sign con­fig­u­ra­tion of the Sir­ius Light Source RF Sys­tem is based on two su­per­con­duct­ing RF cav­i­ties and eight 60 kW solid state am­pli­fiers op­er­at­ing at 500 MHz. The cur­rent con­fig­u­ra­tion, based on a 7-cell room tem­per­a­ture cav­ity, was ini­tially planned for com­mis­sion­ing and ini­tial tests of the beam­lines. How­ever, it will have to re­main in op­er­a­tion longer than planned. Sir­ius has been op­er­at­ing in decay mode for beam­line tests with an ini­tial cur­rent of 70 mA. We pre­sent an overview of the first-year op­er­a­tion of the RF sys­tem and the prepa­ra­tions for the in­stal­la­tion of the two su­per­con­duct­ing cav­i­ties, which is ex­pected to take place in 2023.  
poster icon Poster THPAB347 [1.322 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB347  
About • paper received ※ 16 May 2021       paper accepted ※ 23 July 2021       issue date ※ 16 August 2021  
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THPAB348 INFN-LASA for the PIP-II LB650 Linac SRF, linac, experiment, cryogenics 4474
 
  • R. Paparella, M. Bertucci, M. Bonezzi, A. Bosotti, A. D’Ambros, A.T. Grimaldi, P. Michelato, L. Monaco, D. Sertore
    INFN/LASA, Segrate (MI), Italy
  • C. Pagani
    Università degli Studi di Milano & INFN, Segrate, Italy
  
  INFN joined the in­ter­na­tional ef­fort for the PIP-II pro­ject at Fer­mi­lab and it’s going to con­tribute to the low-beta sec­tion of the PIP-II pro­ton linac. In par­tic­u­lar, INFN-LASA is fi­nal­iz­ing its com­mit­ment to de­liver in kind the full set of the LB650 cav­i­ties, namely 36 plus spares 5-cell cav­i­ties at 650 MHz and geo­met­ri­cal beta 0.61. All cav­i­ties, de­signed by INFN-LASA, will be pro­duced and sur­face treated in in­dus­try, qual­i­fied through ver­ti­cal cold test, and de­liv­ered as ready for string in­stal­la­tion. This paper re­ports the sta­tus of INFN’s con­tri­bu­tion to PIP-II and of on­go­ing ac­tiv­i­ties to­ward the ex­per­i­men­tal qual­i­fi­ca­tions of in­fra­struc­tures and pro­to­types.  
poster icon Poster THPAB348 [4.076 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB348  
About • paper received ※ 16 May 2021       paper accepted ※ 01 July 2021       issue date ※ 01 September 2021  
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THPAB351 INFN-LASA Experimental Activities on PIP-II Low-Beta Cavity Prototypes target, experiment, SRF, superconductivity 4481
 
  • M. Bertucci, A. Bosotti, A. D’Ambros, A.T. Grimaldi, P. Michelato, L. Monaco, C. Pagani, R. Paparella, D. Sertore
    INFN/LASA, Segrate (MI), Italy
  • A. Gresele, A. Torri
    Ettore Zanon S.p.A., Nuclear Division, Schio, Italy
  • M. Rizzi
    Ettore Zanon S.p.A., Schio, Italy
  
  This paper re­ports on the first re­sults ob­tained by INFN-LASA on PIP-II low-beta cav­ity pro­to­types. The goal of this ac­tiv­ity was to val­i­date the ref­er­ence sur­face treat­ment based on Elec­trop­o­l­ish­ing as a bulk re­moval step. The cav­ity treat­ment pro­ce­dures are here pre­sented to­gether with the strat­egy used for their op­ti­miza­tion. The ex­per­i­men­tal re­sults of cav­ity cold tests for a sin­gle cell pro­to­type are pre­sented and dis­cussed. Hav­ing this cav­ity achieved the re­quested per­for­mance, the base­line pro­ce­dure is con­sid­ered as val­i­dated and a plan for a fu­ture high-Q cav­ity sur­face treat­ment is pro­posed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB351  
About • paper received ※ 19 May 2021       paper accepted ※ 23 July 2021       issue date ※ 22 August 2021  
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THPAB352 Computer Vision Techniques Used to Monitor the Alignment of Cavities and Solenoids in the PIP-II Prototype SSR1 Cryomodule solenoid, alignment, target, cryomodule 4485
 
  • S. Zorzetti, J. Bernardini, D. Passarelli
    Fermilab, Batavia, Illinois, USA
  
  The align­ment of the SRF PIP-II string com­po­nents is stud­ied as the ac­cept­able beam de­flec­tion, off­set and de­fo­cus­ing, which may oth­er­wise cause beam loss. Sim­u­la­tions and mea­sure­ments es­tab­lished that the max­i­mum de­vi­a­tion of the beam pipe from the ref­er­ence orbit should not ex­ceed a small frac­tion of the beam aper­ture. To ob­serve the trans­la­tions and ro­ta­tions of each sin­gle com­po­nent within the cry­omod­ule, op­ti­cal in­stru­ments (H-BCAM) sur­vey­ing highly re­flec­tive tar­gets, in­stalled in the in­ter­nal as­sem­bly of the mod­ule were used. The align­ment mon­i­tor­ing con­cept for the PIP II SSR1 pro­to­type cry­omod­ule, along with rel­e­vant mea­sure­ments of the com­po­nents’ po­si­tion mon­i­tor­ing dur­ing cold­mass cooldown is pre­sented in this con­tri­bu­tion. This de­vel­op­ment paves the way to new com­puter vi­sion ap­pli­ca­tions in the field of cry­omod­ule as­sem­blies in clean­room en­vi­ron­ment, in which ro­bot­i­cally-as­sisted op­er­a­tions have the po­ten­tial to dra­mat­i­cally re­duce the risk of chem­i­cal and par­tic­u­late con­t­a­m­i­na­tion.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB352  
About • paper received ※ 19 May 2021       paper accepted ※ 02 August 2021       issue date ※ 28 August 2021  
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THPAB369 Research and Design of an X-Band 100-MeV Compact Electron Accelerator for Very High Energy Electron Therapy in Tsinghua University electron, gun, linac, klystron 4502
 
  • X. Lin, H.B. Chen, J. Shi, C.-X. Tang, H. Zha, L.Y. Zhou
    TUB, Beijing, People’s Republic of China
  
  A 100-MeV Com­pact Elec­tron Ac­cel­er­a­tor scheme based on the Ts­inghua X-band (11.424 GHz) High Power Test stand (TPot-X) was pro­posed for Very High En­ergy Elec­tron (VHEE) ra­dio­ther­apy. A pulse com­pres­sor with cor­rec­tion cav­ity chain was de­signed to com­press the 50 MW, 1500 ns mi­crowave pulse from the X-band kly­stron to 120 MW, 300 ns. The ac­cel­er­a­tion sys­tem con­sists of 3 parts, a buncher which bunches and boosts the elec­tron from a thermionic cath­ode gun to 8 MeV, and two ac­cel­er­at­ing struc­ture which fur­ther boost the elec­tron en­ergy to 100MeV. The de­tailed de­sign and con­sid­er­a­tion are pre­sented in this ar­ti­cle.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB369  
About • paper received ※ 19 May 2021       paper accepted ※ 01 July 2021       issue date ※ 17 August 2021  
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FRXB02 Development of 36 GHz RF Systems for RF Linearisers klystron, HOM, linac, impedance 4518
 
  • A. Castilla, G. Burt
    Lancaster University, Lancaster, United Kingdom
  • M. Behtouei, B. Spataro
    INFN/LNF, Frascati, Italy
  • G. Burt
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • J.C. Cai, A. Castilla, A. Latina, X. Liu, I. Syratchev, X.W. Wu, W. Wuensch
    CERN, Geneva, Switzerland
  • J.C. Cai, A. Castilla
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • A.W. Cross, L. Zhang
    USTRAT/SUPA, Glasgow, United Kingdom
  • L.J.R. Nix
    University of Strathclyde, Glasgow, United Kingdom
  
  Funding: This project has received funding from the European Union’s Horizon2020 research and innovation programme under grant agreement No 777431.
As part of the deign stud­ies, the Com­pact­Light pro­ject plans to use an in­jec­tor in the C-band. Which con­sti­tutes a par­tic­u­lar com­pli­ca­tion for the har­monic sys­tem in charge of lin­earis­ing the beam’s phase space, since it means its op­er­a­tion fre­quency could be higher than the stan­dard X-band RF tech­nolo­gies. In the pre­sent work, we in­ves­ti­gated a 36 GHz (Ka-band) as the ideal fre­quency for the har­monic sys­tem. A set of struc­ture de­signs are pre­sented as can­di­dates for the lin­eariser, based on dif­fer­ent pow­er­ing schemes and pulse com­pres­sor tech­nolo­gies. The com­par­i­son is made both in terms of beam dy­nam­ics and RF per­for­mance. Given the phase sta­bil­ity re­quire­ments for the MW class RF sources needed for this sys­tem, we per­formed care­ful stud­ies of a Gyro-Kly­stron and a multi-beam kly­stron as po­ten­tial RF sources, with both show­ing up to 3 MW avail­able power using mod­er­ate mod­u­la­tor volt­ages. Al­ter­na­tives for pulse com­pres­sion at Ka-band are also dis­cussed in this work. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-FRXB02  
About • paper received ※ 17 May 2021       paper accepted ※ 19 July 2021       issue date ※ 24 August 2021  
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FRXC01 Superconducting Radio-Frequency Cavity Fault Classification Using Machine Learning at Jefferson Laboratory cryomodule, network, SRF, radio-frequency 4535
 
  • C. Tennant, A. Carpenter, T. Powers, L.S. Vidyaratne
    JLab, Newport News, Virginia, USA
  • K.M. Iftekharuddin, M. Rahman
    ODU, Norfolk, Virginia, USA
  • A.D. Shabalina
    STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
  
  Funding: This work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under Contract No. DE-AC05-06OR23177.
We re­port on the de­vel­op­ment of ma­chine learn­ing mod­els for clas­si­fy­ing C100 su­per­con­duct­ing ra­diofre­quency (SRF) cav­ity faults in the Con­tin­u­ous Elec­tron Beam Ac­cel­er­a­tor Fa­cil­ity (CEBAF) at Jef­fer­son Lab. Of the 418 SRF cav­i­ties in CEBAF, 96 are de­signed with a dig­i­tal low-level RF sys­tem con­fig­ured such that a cav­ity fault trig­gers record­ings of RF sig­nals for each of eight cav­i­ties in the cry­omod­ule. Sub­ject mat­ter ex­perts an­a­lyze the col­lected time-se­ries data and iden­tify which of the eight cav­i­ties faulted first and clas­sify the type of fault. This in­for­ma­tion is used to find trends and strate­gi­cally de­ploy mit­i­ga­tions to prob­lem­atic cry­omod­ules. How­ever, man­u­ally la­bel­ing the data is la­bo­ri­ous and time-con­sum­ing. By lever­ag­ing ma­chine learn­ing, near real-time - rather than post­mortem - iden­ti­fi­ca­tion of the of­fend­ing cav­ity and clas­si­fi­ca­tion of the fault type has been im­ple­mented. We dis­cuss the per­for­mance of the ma­chine learn­ing mod­els dur­ing a re­cent physics run. We also dis­cuss ef­forts for fur­ther in­sights into fault types through un­su­per­vised learn­ing tech­niques and pre­sent pre­lim­i­nary work on cav­ity and fault pre­dic­tion using data col­lected prior to a fail­ure event. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-FRXC01  
About • paper received ※ 16 May 2021       paper accepted ※ 01 July 2021       issue date ※ 11 August 2021  
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FRXC06 Development of the Prototype of the Cavity BPM System for SHINE FEL, experiment, electron, controls 4552
 
  • J. Chen, Y.B. Leng, R.X. Yuan
    SSRF, Shanghai, People’s Republic of China
  • S.S. Cao
    SINAP, Shanghai, People’s Republic of China
  • L.W. Lai
    SARI-CAS, Pudong, Shanghai, People’s Republic of China
  
  The Shang­hai high rep­e­ti­tion rate XFEL and ex­treme light fa­cil­ity (SHINE) under con­struc­tion is de­signed as one of the most ad­vanced FEL fa­cil­i­ties in the world, which will pro­duce co­her­ent x-rays with wave­lengths from 0.05 to 3 nm and max­i­mum rep­e­ti­tion rate of 1MHz. In order to achieve pre­cise, sta­ble align­ment of the elec­tron and photo beams in the un­du­la­tor, the pro­to­type of the cav­ity beam po­si­tion mon­i­tors (CBPM) in­clud­ing C-band and X-band have been de­signed and fab­ri­cated for the SHINE. And the re­quire­ment of the trans­verse po­si­tion res­o­lu­tion is bet­ter than 200 nm for a sin­gle bunch of 100 pC at the dy­namic range of ±100 µm. In this paper, we pre­sent the de­sign of the cav­ity with high loaded Q and the RF front-end with low noise-fig­ure, ad­justable gain, sin­gle-stage down-con­ver­sion and phase-locked with ref­er­ence clock, and also de­scribed the struc­ture and spec­i­fi­ca­tions of the home-made data ac­qui­si­tion (DAQ) sys­tem. The con­struc­tion of the ex­per­i­ment plat­form and pre­lim­i­nary mea­sure­ment re­sult with beam at Shang­hai Soft X-ray FEL fa­cil­ity (SXFEL) will be ad­dressed as well.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-FRXC06  
About • paper received ※ 20 May 2021       paper accepted ※ 06 July 2021       issue date ※ 14 August 2021  
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