Accelerator System Design, RF, Injection and Extract
Paper Title Page
MOPAB02 Progress in the Upgrade of the CERN PS Booster Recombination 24
 
  • J.L. Abelleira, W. Bartmann, J. Borburgh, E. Bravin, U. Raich
    CERN, Geneva, Switzerland
 
  The CERN PS Booster re­com­bi­na­tion lines (BT) will be up­graded fol­low­ing the ex­trac­tion en­ergy in­crease fore­seen in 2018 and meant to re­duce the di­rect space-charge tune shift in the PS in­jec­tion for the fu­ture HL-LHC beams. Hence­forth the main line el­e­ments, re­com­bi­na­tion septa, quadrupoles and dipoles must be scaled up to this en­ergy. An in­crease in the beam rigid­ity by a fac­tor 1.3 would re­quire the same fac­tor in the field in­te­gral of the septa, ∫Bdl, in order to bend the same angle and pre­serve the pre­sent re­com­bi­na­tion geom­e­try, which is one of the main up­grade con­straints. This paper de­scribes the new op­tics, in par­tic­u­lar in the new and longer septa. In ad­di­tion we con­sider the up­grade of the so called BTM line that brings the beam to the ex­ter­nal dump and where emit­tance mea­sure­ments are taken thanks to three pairs of grids. The new pro­posed op­tics has also the ad­van­tage to sim­plify the de­sign of the new dipoles. Here we study this new op­tics and the is­sues re­lated to the emit­tance mea­sure­ment at the new higher en­ergy.  
 
MOPAB04 An Overview of the Preparation and Characteristics of the ISIS Stripping Foil 29
 
  • H. V. Smith, B. Jones
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
 
  The ISIS fa­cil­ity at the Ruther­ford Ap­ple­ton Lab­o­ra­tory is a pulsed neu­tron and muon source, for ma­te­ri­als and life sci­ence re­search. H− ions are in­jected into an 800 MeV, 50 Hz rapid cy­cling syn­chro­tron from a 70 MeV lin­ear ac­cel­er­a­tor, over ~130 turns by charge ex­change in­jec­tion. Up to 3·1013 pro­tons per pulse can be ac­cel­er­ated, with the beam cur­rent of 240 μA split be­tween the two spal­la­tion neu­tron tar­gets. The 40 × 120 mm alu­minium oxide strip­ping foils used for in­jec­tion are man­u­fac­tured on-site. This paper gives an overview of the prepa­ra­tion and char­ac­ter­is­tics of the ISIS foils, in­clud­ing mea­sure­ments of foil thick­ness and el­e­men­tal com­po­si­tion. Con­sid­er­a­tion is also given to the beam foot­print on the foil and how this could be op­ti­mised.  
 
TUO1AB01 High Gradient RF System for Upgrade of J-PARC 162
 
  • C. Ohmori, K. Hara, K. Hasegawa, M. Toda, M. Yoshii
    KEK, Ibaraki, Japan
  • M. Nomura, T. Shimada, F. Tamura, M. Yamamoto
    JAEA/J-PARC, Tokai-mura, Japan
  • A. Schnase
    GSI, Darmstadt, Germany
 
  Mag­netic alloy cav­i­ties are suc­cess­fully used for J-PARC syn­chro­trons. These cav­i­ties gen­er­ate much higher RF volt­age than or­di­nary fer­rite-loaded cav­i­ties. The MR (Main Ring) up­grade pro­ject aims to de­liver the beam power of 750 kW to the neu­trino ex­per­i­ment. It in­cludes re­place­ments of all RF cav­i­ties for high rep­e­ti­tion rate of about 1 Hz. By the re­place­ments, the total ac­cel­er­a­tion volt­age will be dou­bled, while power sup­plies and am­pli­fiers re­main the same. The key issue is the de­vel­op­ment of a high gra­di­ent RF sys­tem using high im­ped­ance mag­netic alloy, FT3L. A ded­i­cated pro­duc­tion sys­tem for the FT3L cores with 80 cm di­am­e­ter was as­sem­bled in the J-PARC and demon­strated that we can pro­duce ma­te­r­ial with two times higher muQf prod­uct com­pared to the cores used for pre­sent cav­i­ties. The first 5-cell FT3L cav­ity was as­sem­bled and the sta­tus of high power test is re­ported.  
 
TUO1AB02 Upgrades of the RF Systems in the LHC Injector Complex 165
 
  • H. Damerau, M.E. Angoletta, T. Argyropoulos, P. Baudrenghien, A. Blas, T. Bohl, A.C. Butterworth, A. Findlay, R. Garoby, S.S. Gilardoni, S. Hancock, W. Höfle, J.C. Molendijk, E. Montesinos, M.M. Paoluzzi, D. Perrelet, C. Rossi, E.N. Shaposhnikova
    CERN, Geneva, Switzerland
 
  In the frame­work of the LHC In­jec­tor Up­grade (LIU) pro­ject the ra­dio-fre­quency (RF) sys­tems of the syn­chro­trons in the LHC in­jec­tor chain will un­dergo sig­nif­i­cant im­prove­ments to reach the high beam in­ten­sity and qual­ity re­quired by the High-Lu­mi­nos­ity (HL) LHC. Fol­low­ing the re­cent up­grade of the lon­gi­tu­di­nal beam con­trol sys­tem in the PS Booster (PSB), tests with Finemet cav­i­ties are being per­formed in view of a com­plete re­place­ment of the ex­ist­ing RF sys­tems in the PSB by ones based on this tech­nol­ogy. In the PS a sim­i­lar wide-band Finemet cav­ity has been in­stalled as a lon­gi­tu­di­nal damper. New 1-turn delay feed­backs on the main ac­cel­er­at­ing cav­i­ties to re­duce their im­ped­ance have also been com­mis­sioned. Ad­di­tional feed­back and beam con­trol im­prove­ments are fore­seen. A major up­grade of the main RF sys­tem in the SPS by re­group­ing sec­tions of its trav­el­ling wave cav­i­ties, in­creas­ing the num­ber of cav­i­ties from four to six, will re­duce beam-load­ing and allow higher in­ten­si­ties to be ac­cel­er­ated. The up­grade in­cludes the in­stal­la­tion of two new RF power plants and new feed­back sys­tems. All up­grades will be eval­u­ated with re­spect to their ex­pected ben­e­fits for the beams to the LHC.  
slides icon Slides TUO1AB02 [4.317 MB]  
 
TUO1AB03
Enhancements of the Fermilab Booster to Reduce Losses and Extend Lifetime: The Proton Improvement Plan  
 
  • R.M. Zwaska
    Fermilab, Batavia, Illinois, USA
 
  The Pro­ton Im­prove­ment Plan is a cam­paign of up­grades, im­prove­ments, and re­place­ments of equip­ment in the Fer­mi­lab Pro­ton Source to en­able op­er­a­tion of the ma­chines at higher through­put for an ex­tended pe­riod. The Fer­mi­lab Pro­ton Source is prin­ci­pally com­posed of a 400 MeV linac and Booster syn­chro­tron. This talk will con­cen­trate on a num­ber of im­prove­ments in in­jec­tion, ex­trac­tion, and the RF sys­tems. The notch­ing sys­tem in the Booster has been re­built with shorter kick­ers and a ded­i­cated ab­sorber within the ring. The cog­ging sys­tem is also being changed to a sys­tem using fast mag­netic feed­back, re­plac­ing the pre­vi­ous sys­tem which used ra­dial RF feed­back. A laser-based H neu­tral­iza­tion sys­tem will be im­ple­mented in the linac's MEBT, largely elim­i­nat­ing the loss from notch­ing. The Booster RF sys­tem is un­der­go­ing a com­pre­hen­sive over­haul. The am­pli­fier stages have all been re­placed with a mostly solid-state sys­tem. The cav­i­ties are being com­pre­hen­sively re­fur­bished. Har­monic cav­i­ties will be added. The RF power sys­tems of the drift tube linac are also under study, with pos­si­ble im­ple­men­ta­tion of a 200 MHz kly­stron, and likely im­ple­men­ta­tion of a mod­ern mod­u­la­tor.  
slides icon Slides TUO1AB03 [7.757 MB]  
 
TUO1AB04 Current Status on ESS Medium Energy Beam Transport 170
 
  • I. Bustinduy, M. Magan, F. Sordo
    ESS Bilbao, Bilbao, Spain
  • R. Miyamoto
    ESS, Lund, Sweden
 
  The Eu­ro­pean Spal­la­tion Source, ESS, uses a high power lin­ear ac­cel­er­a­tor for pro­duc­ing in­tense beams of neu­trons. Dur­ing last year the ESS linac cost was reeval­u­ated, as a con­se­quence im­por­tant mod­i­fi­ca­tions were in­tro­duced to the linac de­sign that af­fected Medium En­ergy Beam Trans­port (MEBT) sec­tion. RFQ out­put beam en­ergy in­creased from 3 MeV to 3.62 MeV, and beam cur­rent under nom­i­nal con­di­tions was in­creased from 50 to 62.5mA. The con­sid­ered MEBT is being de­signed pri­mar­ily to match the RFQ out­put beam char­ac­ter­is­tics to the DTL input both trans­ver­sally and lon­gi­tu­di­nally. For this pur­pose a set of eleven quadrupoles is used to match the beam char­ac­ter­is­tics trans­ver­sally, com­bined with three 352.2 MHz CCL type buncher cav­i­ties, which are used to ad­just the beam in order to ful­fill the re­quired lon­gi­tu­di­nal pa­ra­me­ters. Fi­nally, thermo-me­chan­i­cal cal­cu­la­tions for ad­justable halo scrap­ing blades, with sig­nif­i­cant im­pact on the HEBT, will be dis­cussed.  
slides icon Slides TUO1AB04 [5.290 MB]  
 
WEO3AB02 Status of Preparations for a 10 us H Laser-Assisted Stripping Experiment 299
 
  • S.M. Cousineau, A.V. Aleksandrov, V.V. Danilov, T.V. Gorlov, Y. Liu, A.A. Menshov, M.A. Plum, A. Rakhman, A.P. Shishlo
    ORNL, Oak Ridge, Tennessee, USA
  • F.G. Garcia, N.F. Luttrell
    UTK, Knoxville, Tennessee, USA
  • Y. Takeda
    KEK, Ibaraki, Japan
 
  At the Spal­la­tion Neu­tron Source ac­cel­er­a­tor prepa­ra­tions are un­der­way for a 10 us laser-as­sisted H strip­ping ex­per­i­ment. This is a three or­ders of mag­ni­tude in­crease in pulse du­ra­tion com­pared the to ini­tial 2006 proof of prin­ci­ple ex­per­i­ment. The focus of the ex­per­i­ment is the val­i­da­tion of meth­ods that re­duce the av­er­age laser power re­quire­ment, in­clud­ing laser-ion beam tem­po­ral match­ing, ion beam dis­per­sion tai­lor­ing, and spe­cial­ized lon­gi­tu­di­nal and trans­verse op­tics. In this pre­sen­ta­tion we re­port on the sta­tus of prepa­ra­tions and the an­tic­i­pated sched­ule for the ex­per­i­ment.  
slides icon Slides WEO3AB02 [7.250 MB]  
 
WEO3AB03
The Design and Construction Status of Injection and Extraction System for CSNS/RCS  
 
  • S. Wang
    IHEP, Beijing, People's Republic of China
 
  The China Spal­la­tion Neu­tron Source (CSNS) ac­cel­er­a­tor con­sists of an 80MeV H linac and a 1.6GeV pro­ton Rapid Cy­cling Syn­chro­tron(RCS), and it pro­vides 100 kW beam to neu­tron tar­get. The in­jec­tion and ex­trac­tion sys­tems play an im­por­tant role in the RCS. The H strip­ping paint­ing and sin­gle turn ex­trac­tion are adopted in the RCS. Now the hard­ware of the in­jec­tion and ex­trac­tion sys­tems are being fab­ri­cated and tested. The de­sign of the in­jec­tion sys­tem and ex­trac­tion sys­tem of the RCS are in­tro­duced, in­clud­ing some sim­u­la­tion study and op­ti­miza­tion. The con­struc­tion sta­tus of hard­ware is also de­scribed, in­clud­ing the test re­sults of hard­ware of the in­jec­tion and ex­trac­tion sys­tems.  
slides icon Slides WEO3AB03 [5.085 MB]  
 
WEO4AB01 Radio Frequency Quadrupole for Landau Damping in Accelerators. Analytical and numerical studies. 315
 
  • A. Grudiev, K.S.B. Li
    CERN, Geneva, Switzerland
  • M. Schenk
    LHEP, Bern, Switzerland
 
  It is pro­posed to use a radio fre­quency quadru­pole (RFQ) to in­tro­duce a lon­gi­tu­di­nal spread of the be­ta­tron fre­quency for Lan­dau damp­ing of trans­verse beam in­sta­bil­i­ties in cir­cu­lar ac­cel­er­a­tors. The ex­ist­ing the­ory of sta­bil­ity di­a­grams for Lan­dau damp­ing is ap­plied to the case of an RFQ. As an ex­am­ple, the re­quired quadrupo­lar strength is cal­cu­lated for sta­bi­liz­ing the Large Hadron Col­lider (LHC) beams at 7 TeV. It is shown that this strength can be pro­vided by a su­per­con­duct­ing RF de­vice which is only a few me­ters long. Fur­ther­more, the sta­bi­liz­ing ef­fect of such a de­vice is proven nu­mer­i­cally by means of the Py­HEAD­TAIL macropar­ti­cle track­ing code for the case of a slow head-tail in­sta­bil­ity ob­served in the LHC at 3.5 TeV.  
slides icon Slides WEO4AB01 [1.991 MB]  
 
WEO4AB02 New PSB H Injection and 2 GeV Transfer to the CERN PS 320
 
  • W. Bartmann, J.L. Abelleira, B. Balhan, E. Benedetto, J. Borburgh, C. Bracco, C. Carli, G.P. Di Giovanni, V. Forte, S.S. Gilardoni, B. Goddard, G. Gräwer, K. Hanke, M. Hourican, A. Huschauer, M. Meddahi, B. Mikulec, G. Rumolo, L. Sermeus, R. Steerenberg, G. Sterbini, Z. Szoke, R. Wasef, Y. Wei, W.J.M. Weterings
    CERN, Geneva, Switzerland
 
  At CERN Linac4 is being com­mis­sioned as first step in the LHC in­jec­tor up­grade to pro­vide 160 MeV H ions. In order to fully de­ploy its po­ten­tial, the PSB con­ven­tional mul­ti­turn in­jec­tion will be re­placed by a charge ex­change in­jec­tion. An ex­pected bright­ness im­prove­ment of about a fac­tor 2 would then be dif­fi­cult to di­gest at PS in­jec­tion due to space charge. There­fore the trans­fer en­ergy be­tween PSB and PS will be in­creased at the same time from 1.4 to 2 GeV. This paper de­scribes the new PSB in­jec­tion sys­tem and the sta­tus of its test stand. Mod­i­fi­ca­tions of the PSB ex­trac­tion and re­com­bi­na­tion septa and kick­ers in the trans­fer line are shown. A new fo­cussing struc­ture for the trans­fer lines to match the hor­i­zon­tal dis­per­sion at PS in­jec­tion and the de­sign of a new eddy cur­rent sep­tum for the PS in­jec­tion are pre­sented.  
slides icon Slides WEO4AB02 [2.867 MB]  
 
WEO4AB03
Study on the Beam Distribution and Painting Range during the Injection Process for CSNS/RCS  
 
  • M.Y. Huang, N. Huang, J. Qiu, S. Wang
    IHEP, Beijing, People's Republic of China
 
  Funding: Work supported by National Natural Science Foundation of China (11205185, 11175020, 11175193)
In this paper, firstly, we stud­ied the beam dis­tri­b­u­tion dur­ing the in­jec­tion process for the Rapid Cy­cling Syn­chro­tron of the China Spal­la­tion Neu­tron Source (CSNS/RCS). The in­jec­tion processes with and with­out the space charge were both sim­u­lated by the code ORBIT, and the beam dis­tri­b­u­tion of each turn can be ob­tained. Then, the par­ti­cle mo­tion dur­ing the in­jec­tion process can be stud­ied and the beam aper­ture which was re­quired can be ob­tained. Sec­ondly, the in­jec­tion processes for dif­fer­ent trans­verse phase space paint­ing ranges were dis­cussed and sim­u­lated. Then, the op­ti­mized paint­ing range for CSNS/RCS can be ob­tained.
 
slides icon Slides WEO4AB03 [0.977 MB]  
 
THO3AB02 Dynamic Correction of Extraction Beam Displacement by Field Ringing of Extraction Pulsed Kicker Magnets in the J-PARC 3-GeV RCS 389
 
  • H. Harada, H. Hotchi, S.I. Meigo, P.K. Saha, F. Tamura
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
 
  The 3-GeV rapid cy­cling syn­chro­tron (RCS) of J-PARC is de­signed for a high-in­ten­sity out­put beam power of 1MW. The RCS is ex­tracted two bunches by using eight pulsed kicker and three DC sep­tum mag­nets with 25Hz rep­e­ti­tion. The ex­tracted beam is si­mul­ta­ne­ously de­liv­ered to the ma­te­r­ial and life sci­ence ex­per­i­men­tal fa­cil­ity (MLF) as well as the 50-GeV main ring syn­chro­tron (MR). The kicker mag­nets have the ring­ing of flat-top field and the ring­ing causes the po­si­tion dis­place­ment. The dis­place­ment is big issue be­cause it causes an emit­tance growth of the ex­tracted beam di­rectly. In the beam tun­ing, we per­formed a tim­ing scan of each kicker mag­net by using a shorter pulse beam in order to un­der­stand the char­ac­ter­is­tics of ring­ing field. We then care­fully op­ti­mized the trig­ger tim­ings of each kicker for the ring­ing com­pen­sa­tion. We have suc­cess­fully com­pen­sated the ex­tracted beam dis­place­ments to (min., max.) = (1.1 mm, +0.6 mm) as com­pared to (14 mm, +10 mm) with no ring­ing com­pen­sa­tion. The pro­ce­dure for ring­ing com­pen­sa­tion and ex­per­i­men­tal re­sults are re­ported in this paper.  
 
THO3AB03 Pulse-to-pulse Transverse Beam Emittance Controlling for the MLF and MR in the 3-GeV RCS of J-PARC 394
 
  • P.K. Saha, H. Harada, H. Hotchi, T. Takayanagi
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
 
  The 3-GeV RCS (Rapid Cy­cling Syn­chro­tron) of J-PARC (Japan Pro­ton Ac­cel­er­a­tor Re­search Com­plex) is a MW-class pro­ton beam source for the muon and neu­tron pro­duc­tion tar­gets in the MLF (Ma­te­r­ial and Life Sci­ence Ex­per­i­men­tal Fa­cil­ity) as well as an in­jec­tor for 50-GeV MR (Main Ring). Not only the beam in­ten­sity but RCS has to pro­vide two dif­fer­ent trans­verse sizes of the ex­tracted beam for the MLF and MR even in si­mul­ta­ne­ous op­er­a­tion. Namely, a wider one for the MLF, while a nar­rower one for the MR. We pro­posed a pulse-to-pulse di­rect con­trol­ling of the trans­verse in­jec­tion paint­ing area so as to en­sure a de­sired ex­tracted beam emit­tance. The in­jec­tion sys­tem de­sign is ca­pa­ble of chang­ing paint­ing area be­tween MLF and MR. The ex­tracted beam pro­file for the MR is mea­sured to be suf­fi­ciently nar­rower than that for the MLF and is also shown to be con­sis­tent with ORBIT beam sim­u­la­tions. It is thus one re­mark­able progress in re­cent high in­ten­sity multi-user ma­chine to con­firm that the beam pa­ra­me­ters can be dy­nam­i­cally con­trolled and de­liv­ered as re­quested by the users even in si­mul­ta­ne­ous op­er­a­tion. A de­tail of both de­sign and ex­per­i­men­tal stud­ies are pre­sented in this paper.  
slides icon Slides THO3AB03 [2.225 MB]  
 
THO3AB04 Modeling and Feedback Design Techniques for Controlling Intra-bunch Instabilities at CERN SPS Ring 399
 
  • C.H. Rivetta, J.D. Fox, O. Turgut
    SLAC, Menlo Park, California, USA
  • W. Höfle, K.S.B. Li
    CERN, Geneva, Switzerland
 
  Funding: Work supported by the U.S. Department of Energy under contract # DE-AC02-76SF00515 and the US LHC Accelerator Research Program (LARP).
The feed­back con­trol of in­tra-bunch in­sta­bil­i­ties dri­ven by elec­tron-clouds or strong head-tail cou­pling (trans­verse mode cou­pled in­sta­bil­i­ties –TMCI) re­quires band­width suf­fi­cient to sense the ver­ti­cal po­si­tion and apply mul­ti­ple cor­rec­tions within a nanosec­ond-scale bunch. These re­quire­ments im­pose chal­lenges and lim­its in the de­sign and im­ple­men­ta­tion of the feed­back sys­tem. This paper pre­sents model-based de­sign tech­niques for feed­back sys­tems to ad­dress the sta­bi­liza­tion of the trans­verse bunch dy­nam­ics. These tech­niques in­clude in the de­sign the ef­fect of noise and sig­nals per­turb­ing the bunch mo­tion. They also in­clude re­al­is­tic lim­i­ta­tions such as band­width, non­lin­ear­i­ties in the hard­ware and max­i­mum power de­liv­er­able. Ro­bust­ness of the sys­tem is eval­u­ated as a func­tion of pa­ra­me­ter vari­a­tions of the bunch.
 
slides icon Slides THO3AB04 [2.153 MB]