Author: Spataro, B.
Paper Title Page
MOPAB270 Beam Dynamics Studies in a Standing Wave Ka-band Linearizer 857
 
  • J. Scifo, M. Behtouei, L. Faillace, M. Ferrario, A. Giribono, B. Spataro, C. Vaccarezza
    INFN/LNF, Frascati, Italy
  • M. Migliorati
    INFN-Roma1, Rome, Italy
  • M. Migliorati
    Sapienza University of Rome, Rome, Italy
  • G. Torrisi
    INFN/LNS, Catania, Italy
  
  Next-gen­er­a­tion FEL user fa­cil­i­ties re­quire high-qual­ity elec­tron beams with kA peak cur­rent. The com­bi­na­tion of a high bright­ness RF in­jec­tor and a mag­netic com­pres­sion stage rep­re­sents a very per­for­mant so­lu­tion in terms of elec­tron beam emit­tance and peak cur­rent. One of the im­por­tant is­sues is the de­sign of a proper de­vice that acts as a lin­earizer for the beam lon­gi­tu­di­nal phase space. Re­cently, the de­sign of a SW Ka band RF ac­cel­er­at­ing struc­ture has been pro­posed with promis­ing re­sults. The paper re­ports on elec­tron beam dy­nam­ics stud­ies in the de­scribed RF struc­ture.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB270  
About • paper received ※ 19 May 2021       paper accepted ※ 29 August 2021       issue date ※ 26 August 2021  
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MOPAB353 Design of a compact Ka-Band Mode Launcher for High-gradient Accelerators 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 ※ 27 August 2021  
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MOPAB410 Preliminary Studies of a Compact VHEE Linear Accelerator System for FLASH Radiotherapy 1229
 
  • L. Giuliano, F. Bosco, M. Carillo, D. De Arcangelis, L. Faillace, L. Ficcadenti, M. Migliorati, A. Mostacci, L. Palumbo
    Sapienza University of Rome, Rome, Italy
  • D. Alesini, M. Behtouei, B. Spataro
    INFN/LNF, Frascati, Italy
  • G. Cuttone, G. Torrisi
    INFN/LNS, Catania, Italy
  • V. Favaudon, S. Heinrich, A. Patriarca
    Institut Curie - Centre de Protonthérapie d’Orsay, Orsay, France
  
  Funding: The work is supported by La Sapienza University, research grant "grandi progetti di ricerca 2020".
The Flash Radio Ther­apy is a rev­o­lu­tion­ary new tech­nique in the can­cer cure: it spares healthy tis­sue from the dam­age of the ion­iz­ing ra­di­a­tion main­tain­ing the tumor con­trol as ef­fi­cient as in con­ven­tional ra­dio­ther­apy. To allow the im­ple­men­ta­tion of the FLASH Ther­apy con­cept into ac­tual clin­i­cal use, it is nec­es­sary to have a lin­ear ac­cel­er­a­tor able to de­liver the very high dose and very high dose rate (>106 Gy/s) in a very short ir­ra­di­a­tion time (beam on time < 100ms). Low en­ergy S-band Linacs (up to 7 MeV) are being used in Ra­dio­bi­ol­ogy and pre-clinic ap­pli­ca­tions but in order to treat deep tu­mors, the en­ergy of the elec­trons should achieve the range of 60-100 MeV. In this paper, we ad­dress the main is­sues in the de­sign of a com­pact C band (5.712 GHz) elec­tron linac-VHEE for FLASH Radio Ther­apy. We pre­sent pre­lim­i­nary stud­ies on C-band struc­tures at La Sapienza and at INFN-LNS, aim­ing to reach a high ac­cel­er­at­ing gra­di­ent and high cur­rent nec­es­sary to de­liver a dose >1 Gy/pulse, with very short elec­tron pulse. 		 
poster icon Poster MOPAB410 [0.650 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB410  
About • paper received ※ 19 May 2021       paper accepted ※ 09 June 2021       issue date ※ 21 August 2021  
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WEPAB051 Beam Dynamics for a High Field C-Band Hybrid Photoinjector 2714
 
  • L. Faillace, F. Bosco, M. Carillo, L. Giuliano, M. Migliorati, A. Mostacci, L. Palumbo
    Sapienza University of Rome, Rome, Italy
  • R.B. Agustsson, I.I. Gadjev, S.V. Kutsaev, A.Y. Murokh
    RadiaBeam, Santa Monica, California, USA
  • M. Behtouei, A. Giribono, B. Spataro, C. Vaccarezza
    INFN/LNF, Frascati, Italy
  • A. Fukasawa, N. Majernik, J.B. Rosenzweig, O. Williams
    UCLA, Los Angeles, California, USA
  • S.G. Tantawi
    SLAC, Menlo Park, California, USA
  
  Funding: This work supported by DARPA GRIT under contract no. 20204571 and partially by INFN National Committee V through the ARYA project.
In this paper, we pre­sent a new class of a hy­brid pho­toin­jec­tor in C-Band. This pro­ject is the ef­fort re­sult of a UCLA/Sapienza/INFN-LNF/SLAC/Ra­di­a­Beam col­lab­o­ra­tion. This de­vice is an in­te­grated struc­ture con­sist­ing of an ini­tial stand­ing-wave 2.5-cell gun con­nected to a trav­el­ing-wave sec­tion at the input cou­pler. Such a scheme nearly avoids power re­flec­tion back to the kly­stron, re­mov­ing the need for a high-power cir­cu­la­tor. It also in­tro­duces strong ve­loc­ity bunch­ing due to a 90° phase shift in the ac­cel­er­at­ing field. A rel­a­tively high cath­ode elec­tric field of 120 MV/m pro­duces a ~4 MeV beam with ~20 MW input RF power in a small foot-print. The beam trans­verse dy­nam­ics are con­trolled with a ~0.27 T fo­cus­ing so­le­noid. We show the sim­u­la­tion re­sults of the RF/mag­netic de­sign and the op­ti­mized beam dy­nam­ics that shows 6D phase space com­pen­sa­tion at 250 pC. Proper beam shap­ing at the cath­ode yields a ~0.5 mm-mrad trans­verse emit­tance. A beam waist oc­curs si­mul­ta­ne­ously with a lon­gi­tu­di­nal focus of <400 fs rms and peak cur­rent >600 A. We dis­cuss ap­pli­ca­tion of this in­jec­tor to an In­verse-Comp­ton Scat­ter­ing sys­tem and pre­sent cor­re­spond­ing start-to-end beam dy­nam­ics sim­u­la­tions. 		 
poster icon Poster WEPAB051 [0.827 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB051  
About • paper received ※ 18 May 2021       paper accepted ※ 01 July 2021       issue date ※ 15 August 2021  
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WEPAB238 Modeling Short Range Wakefield Effects in a High Gradient Linac 3185
 
  • F. Bosco, M. Carillo, L. Faillace, L. Giuliano, M. Migliorati, A. Mostacci, L. Palumbo
    Sapienza University of Rome, Rome, Italy
  • M. Behtouei, L. Faillace, A. Giribono, B. Spataro, C. Vaccarezza
    INFN/LNF, Frascati, Italy
  • F. Bosco, M. Migliorati
    INFN-Roma1, Rome, Italy
  • L. Giuliano, A. Mostacci, L. Palumbo
    INFN-Roma, Roma, Italy
  • J.B. Rosenzweig
    UCLA, Los Angeles, California, USA
  
  Funding: This work is supported by DARPA GRIT under contract no. 20204571 and partially by INFN National committee V through the ARYA project.
The in­ter­ac­tion of charged beams with the sur­round­ing ac­cel­er­at­ing struc­tures re­quires a thor­ough in­ves­ti­ga­tion due to po­ten­tial neg­a­tive ef­fects on the phase space qual­ity. In­deed, the wake­fields act­ing back on the beam are re­spon­si­ble for emit­tance di­lu­tion and in­sta­bil­i­ties, such as the beam break-up, which limit the per­for­mances of elec­tron-based ra­di­a­tion sources and lin­ear col­lid­ers. Here we in­tro­duce a new track­ing code which is meant to in­ves­ti­gate the ef­fects of short-range trans­verse wake­fields in lin­ear ac­cel­er­a­tors. The track­ing is based on quasi-an­a­lyt­i­cal mod­els for the beam dy­nam­ics which, in ad­di­tion to the basic op­tics spec­i­fied by the ap­plied fields, in­clude di­pole wake­field forces and a sim­ple ap­proach to ac­count for space-charge ef­fects. Such fea­tures pro­vide a re­li­able tool which eas­ily al­lows to in­spect the per­for­mances of a linac. To val­i­date the model, a par­al­lel analy­sis for a ref­er­ence case is per­formed with well-known beam dy­nam­ics codes, and com­par­isons are shown. As an il­lus­tra­tive ap­pli­ca­tion, we dis­cuss a study on align­ment tol­er­ances eval­u­at­ing the emit­tance growth in­duced by mis­aligned ac­cel­er­at­ing sec­tions. 		 
poster icon Poster WEPAB238 [1.747 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB238  
About • paper received ※ 18 May 2021       paper accepted ※ 07 July 2021       issue date ※ 01 September 2021  
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WEPAB256 Three-Dimensional Space Charge Oscillations in a Hybrid Photoinjector 3240
 
  • M. Carillo, M. Behtouei, F. Bosco, L. Faillace, A. Giribono, L. Giuliano, M. Migliorati, A. Mostacci, L. Palumbo
    Sapienza University of Rome, Rome, Italy
  • L. Ficcadenti
    INFN-Roma, Roma, Italy
  • J.B. Rosenzweig
    UCLA, Los Angeles, California, USA
  • B. Spataro, C. Vaccarezza
    INFN/LNF, Frascati, Italy
  
  Funding: This work supported by DARPA GRIT under contract no. 20204571 and partially by INFN National committee V through the ARYA project.
A new hy­brid C-band photo-in­jec­tor, con­sist­ing of a stand­ing wave RF gun con­nected to a trav­el­ing wave struc­ture, op­er­at­ing in a ve­loc­ity bunch­ing regime, has shown to pro­duce an ex­tremely high bright­ness beam with very low emit­tance and a very high peak cur­rent through a si­mul­ta­ne­ous com­pres­sion of the beam in the lon­gi­tu­di­nal and trans­verse di­men­sions. A beam slice analy­sis has been per­formed in order to un­der­stand the evo­lu­tion of the rel­e­vant phys­i­cal pa­ra­me­ters of the beam in the lon­gi­tu­di­nal and trans­verse phase spaces along the struc­ture. A sim­ple model for the en­ve­lope equa­tion has been de­vel­oped to de­scribe the beam be­hav­ior in this par­tic­u­lar dy­nam­ics regime that we term "triple waist", since all three di­men­sions reach a min­i­mum con­di­tion al­most si­mul­ta­ne­ously. The model an­a­lyzes the trans­verse en­ve­lope dy­nam­ics at the exit of the hy­brid photo-in­jec­tor, in the down­stream drift where the triple waist oc­curs. The an­a­lyt­i­cal so­lu­tions ob­tained from the en­ve­lope equa­tion are com­pared with the sim­u­la­tions, show­ing a good agree­ment. Fi­nally, these re­sults have been an­a­lyzed also in terms of plasma os­cil­la­tion to ob­tain a fur­ther phys­i­cal in­ter­pre­ta­tion of the beam dy­nam­ics. 		 
poster icon Poster WEPAB256 [1.162 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB256  
About • paper received ※ 19 May 2021       paper accepted ※ 21 July 2021       issue date ※ 13 August 2021  
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WEPAB398 A C-Band RF Mode Launcher with Quadrupole Field Components Cancellation for High Brightness Applications 3638
 
  • G. Pedrocchi
    SBAI, Roma, Italy
  • D. Alesini, F. Cardelli, A. Gallo, A. Giribono, B. Spataro
    INFN/LNF, Frascati, Italy
  • G. Castorina
    AVO-ADAM, Meyrin, Switzerland
  • L. Ficcadenti
    INFN-Roma, Roma, Italy
  • M. Migliorati, A. Mostacci, L. Palumbo
    Sapienza University of Rome, Rome, Italy
  
  The R&D of high gra­di­ent ra­diofre­quency de­vices is aimed to de­velop in­no­v­a­tive and com­pact ac­cel­er­at­ing stuc­tures based on new man­u­fac­tor­ing tech­niques and ma­te­ri­als in order to pro­duce de­vices op­er­at­ing with the high­est ac­cel­er­at­ing gra­di­ent. Re­cent stud­ies have shown a large in­crease in the max­i­mum sus­tained RF sur­face elec­tric fields in cop­per struc­ture op­er­at­ing at cryo­genic tem­per­a­ture. These novel ap­proaches allow sig­nif­i­cant per­for­mance im­prove­ments of RF pho­toin­jec­tors. In­deed the op­er­a­tion at high sur­face fields re­sults in con­sid­er­able in­crease of elec­tron bril­liance. This re­quires high field qual­ity in the RF pho­toin­jec­tor and specif­i­cally in its poweer cou­pler. In this work we pre­sent a novel power cou­pler for the RF pho­toin­jec­tor. The cou­pler is a com­pact C-band TM01 mode launcher with a four­fold sym­me­try which min­i­mized both the di­pole and the quadru­pole RF field com­po­nents.  
poster icon Poster WEPAB398 [1.799 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB398  
About • paper received ※ 13 May 2021       paper accepted ※ 06 July 2021       issue date ※ 23 August 2021  
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FRXB02 Development of 36 GHz RF Systems for RF Linearisers 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, Meyrin, 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 ※ 25 August 2021  
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