Keyword: space-charge
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MOPAB028 Estimation of Longitudinal Dimensions of Sub-Picosecond Electron Bunches with the 3-Phase Method booster, electron, simulation, gun 139
 
  • H. Purwar, C. Bruni, A. Gonnin
    LAL, Orsay, France
  • T. Vinatier
    DESY, Hamburg, Germany
  
  An es­ti­ma­tion of the lon­gi­tu­di­nal di­men­sions for short elec­tron bunches in an ac­cel­er­at­ing field is an im­por­tant di­ag­nos­tic and can be ex­tremely help­ful in eval­u­at­ing the per­for­mance of an ac­cel­er­a­tor. We in­ves­ti­gate a method for close es­ti­ma­tion of bunch length for sub-pi­cosec­ond elec­tron bunches from the mea­sure­ment of their en­ergy spreads. Three or more mea­sure­ments for the bunch en­ergy spread are made by vary­ing the phase of the ac­cel­er­at­ing struc­ture and later a re­con­struc­tion of the bunch lon­gi­tu­di­nal di­men­sions, namely bunch length, ini­tial en­ergy spread and chirp at the en­trance of the ac­cel­er­at­ing struc­ture are ob­tained using the least square method. A com­par­i­son of the ob­tained re­sults with ASTRA sim­u­la­tions is also in­cluded to val­i­date the 3-phase method for sub-ps elec­tron bunches. It is a sim­ple method from both un­der­stand­ing (easy re­con­struc­tion using trans­port ma­tri­ces) and ex­per­i­men­tal point of views (mul­ti­ple mea­sure­ments of en­ergy spread with vary­ing phase of the ac­cel­er­at­ing struc­ture).  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB028  
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MOPAB039 Development of a Control System Based on Experimental Data for Space Charge Lenses electron, plasma, operation, ion 166
 
  • S. Klaproth, C. Beberweil, M. Droba, O. Meusel, H. Podlech, B.E.J. Scheible, K. Schulte, K.I. Thoma, C. Wagner
    IAP, Frankfurt am Main, Germany
  
  Space charge lenses use a con­fined elec­tron cloud for the fo­cus­ing of ion beams. The elec­tron den­sity gives the fo­cus­ing strength whereas the den­sity dis­tri­b­u­tion in­flu­ences the map­ping qual­ity of the space charge lens and is re­lated to the con­fine­ment. The major role of the elec­tron den­sity with re­spect to the fo­cus­ing qual­ity has been pointed out many times in the past *,**. With an au­to­mated mea­sure­ment sys­tem the ra­dial light den­sity pro­file, plasma sta­bil­ity and mean value of the elec­tron den­sity have been mea­sured in re­spect to the con­fin­ing fields and the pres­sure. The re­sults are sum­ma­rized in 3D-maps. The the­o­ret­i­cal model ap­prox­i­ma­tions for space charge lenses pre­dicts high elec­tron den­si­ties then mea­sured. With the au­to­mated sys­tem the re­al­is­tic 3D-maps can be con­sid­ered in­stead of an ap­prox­i­ma­tion of a the­o­ret­i­cal den­sity in­clud­ing knowl­edge of the most sta­ble elec­tron cloud achiev­able within the pa­ra­me­ter range of the lens. The ex­per­i­men­tal re­sults of the au­to­mated mea­sure­ment sys­tem will be pre­sented here and a con­cept of a con­trol sys­tem for this type of space charge lenses will be ex­plained.
* O. Meusel, 'Focussing and transport of ion beams using space charge lenses', PhD thesis, 2006 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB039  
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MOPAB045 Reconstruction of the 3D Charge Distribution of an Electron Bunch Using a Novel Variable-Polarization Transverse Deflecting Structure (TDS) simulation, electron, experiment, laser 188
 
  • D. Marx, R.W. Aßmann, U. Dorda, U. Dorda, B. Marchetti
    DESY, Hamburg, Germany
  • P. Craievich
    PSI, Villigen PSI, Switzerland
  • A. Grudiev, A. Grudiev, A. Grudiev
    CERN, Geneva, Switzerland
  
  A TDS is a well-known de­vice for the char­ac­ter­i­za­tion of the lon­gi­tu­di­nal prop­er­ties of an elec­tron bunch in a lin­ear ac­cel­er­a­tor. So far, the cor­re­la­tion of the slice prop­er­ties in the hor­i­zon­tal/ver­ti­cal planes of the elec­tron bunch dis­tri­b­u­tion has been char­ac­ter­ized by using a TDS sys­tem de­flect­ing in the ver­ti­cal/hor­i­zon­tal di­rec­tions re­spec­tively and analysing the image on a sub­se­quent screen*. Re­cently, an in­no­v­a­tive de­sign for a TDS struc­ture has been pro­posed, which in­cludes the pos­si­bil­ity of con­tin­u­ously vary­ing the angle of the trans­verse streak­ing field in­side a TDS struc­ture**. This al­lows the beam dis­tri­b­u­tion to be char­ac­ter­ized in all trans­verse di­rec­tions. By col­lect­ing mea­sure­ments of bunches streaked at dif­fer­ent an­gles and com­bin­ing them using to­mo­graphic tech­niques, it is pos­si­ble to re­trieve 3D dis­tri­b­u­tions of the charge den­sity. In this paper, a method is pro­posed and sim­u­la­tion re­sults are pre­sented to show the fea­si­bil­ity of such an ap­proach at the up­com­ing ac­cel­er­a­tor R&D fa­cil­ity, SIN­BAD, at DESY***.
* M. Roehrs et al., Phys. Rev. ST Accel. Beams 12, 050704 (2009).
** A. Grudiev, Report No. CLIC-Note-1067, 2016.
*** B. Marchetti et al. X-band TDS project contribution to these conference proceedings.
 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB045  
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MOPAB048 Simulation of fs Bunch Length Determination with the 3-Phase Method and THz Dielectric Loaded Waveguides injection, linac, simulation, electron 199
 
  • T. Vinatier, R.W. Aßmann, U. Dorda, B. Marchetti
    DESY, Hamburg, Germany
  
  In this paper, we in­ves­ti­gate with ASTRA sim­u­la­tions the ca­pa­bil­ity of the 3-phase method to re­con­struct the length of a fs elec­tron bunch. We show that a stan­dard 3 GHz trav­el­ling wave ac­cel­er­at­ing struc­ture is not suited for this pur­pose, be­cause of the too im­por­tant ef­fect of the space-charge forces and of the too small vari­a­tions of the in­duced en­ergy spread with the bunch in­jec­tion phase. Our sim­u­la­tions demon­strate that the use of di­elec­tric-loaded wave­guides dri­ven by THz pulses would allow over­com­ing these two lim­i­ta­tions and pos­si­bly achiev­ing an ul­ti­mate res­o­lu­tion bet­ter than 5% for the de­ter­mi­na­tion of a 6.25 fs rms bunch length at 100 MeV en­ergy and 1 pC charge. The next steps of the study to bet­ter eval­u­ate, in sim­u­la­tions and ex­per­i­ments, the pos­si­ble sources of degra­da­tion of the 3-phase method res­o­lu­tion are also men­tioned.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB048  
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MOPAB137 Validation of a Novel Emittance Diagnostic Method for Beams with Significant Space Charge emittance, focusing, quadrupole, simulation 451
 
  • R.B. Fiorito, C.P. Welsch, H.D. Zhang
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • M.E. Conde, N.R. Neveu, J.F. Power
    ANL, Argonne, Illinois, USA
  • O. Mete Apsimon
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • A.G. Shkvarunets
    UMD, College Park, Maryland, USA
  
  Funding: Work supported by the EU under grant agreement 624890, the STFC Cockcroft Institute Core Grant No. ST/G008248/1.
Exact knowl­edge of beam emit­tance is of cen­tral im­por­tance for es­sen­tially every ac­cel­er­a­tor. How­ever, there are only few meth­ods to de­ter­mine it when the beam has sig­nif­i­cant space charge. We re­port on our progress to val­i­date a novel di­ag­nos­tic method that has been pro­posed to de­ter­mine the RMS emit­tance of an elec­tron beam with space charge. This method uses RMS di­ver­gence and beam size data mea­sured at a screen placed in a free drift re­gion for se­lected val­ues of mag­netic fo­cus­ing strength. A novel al­go­rithm is then used to de­ter­mine the cross cor­re­la­tion term and con­se­quently the RMS emit­tance of the beam. Sim­u­la­tions, quadru­pole scans, phase space to­mog­ra­phy and op­ti­cal dif­frac­tion-di­elec­tric foil ra­di­a­tion in­ter­fer­om­e­try are cur­rently being em­ployed to de­ter­mine and com­pare the hor­i­zon­tal (x) and ver­ti­cal (y) emit­tances of the 14 MeV wit­ness elec­tron beam at Ar­gonne Na­tional Lab­o­ra­tory's Wake­field Ac­cel­er­a­tor. The re­sults of sim­u­la­tions and cur­rent mea­sure­ments are pre­sented and the ad­van­tages of the new tech­nique are dis­cussed. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB137  
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MOPIK075 Design, Simulation and Compare of Flat Cathode Electron Guns with Spherical Cathode Electron Guns for Industrial Accelerators cathode, gun, electron, simulation 702
 
  • M. Nazari, F. Abbasi
    Shahid Beheshti University, Tehran, Iran
  • S. Ahmadiannamin
    ILSF, Tehran, Iran
  • F. Ghasemi
    NSTRI, Tehran, Iran
  • S. Haghtalab
    IPM, Tehran, Iran
  
  In this ar­ti­cle, elec­tron guns with flat and spher­i­cal cath­odes have been de­signed and sim­u­lated for in­dus­trial ac­cel­er­a­tors. After check­ing the dif­fer­ent fea­tures of each cath­ode geom­e­try, there has been dis­cussed about op­ti­mum val­ues of this fea­tures. The most im­por­tant fea­tures in se­lect­ing the best cath­ode geom­e­try for in­dus­trial ac­cel­er­a­tors are beam waist ra­dius, beam waist po­si­tion, cur­rent den­sity and price. Fi­nally after com­par­ing the dif­fer­ent fea­tures of both geome­tries with each other, suit­able geom­e­try was se­lected.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK075  
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MOPIK113 Beam Phase Space Tomography for FXR LIA emittance, simulation, solenoid, electron 801
 
  • Y.H. Wu, Y.-J. Chen
    LLNL, Livermore, California, USA
  
  Funding: This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
Know­ing the ini­tial beam pa­ra­me­ters en­ter­ing an ac­cel­er­a­tor or a down­stream beam­line al­lows us to se­lect trans­port tunes op­ti­mized for a de­sired ac­cel­er­a­tor per­for­mance. In this study, we re­port un­fold­ing LLNL's FXR [1] beam pa­ra­me­ters by using the to­mog­ra­phy tech­nique [2, 3] to con­struct the beam phase space along the ac­cel­er­a­tor's down­stream beam­line. The un­folded phase spaces from to­mog­ra­phy and sim­u­la­tions are con­sis­tent. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK113  
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TUPAB142 Tracking of Electrons Created at Wrong RF Phases in the RHIC Low Energy Cooler electron, cathode, cavity, laser 1666
 
  • J. Kewisch, A.V. Fedotov, D. Kayran, S. Seletskiy
    BNL, Upton, Long Island, New York, USA
  
  Funding: Work supported by the US Department of Energy under contract No. DE-SC0012704.
The RHIC Low En­ergy Cooler will be based on a 400 keV DC elec­tron gun with a photo-cath­ode and a 2.2 MeV SRF booster cav­ity. Elec­tron that leave the cath­ode at the wrong time may be de­cel­er­ated and turned around in the booster and re­turn to the cath­ode with en­er­gies up to 1 MeV. On the way back these elec­tron will en­counter the de­fo­cussing EM fields up to nine fol­low­ing elec­tron bunches. Such elec­trons may be cre­ated for var­i­ous rea­sons: Cos­mic rays, stray laser light in­clud­ing a cat­a­strophic fail­ure of the laser tim­ing sys­tem or as sec­on­daries of re­turn­ing elec­trons. We pre­sent track­ing re­sults from the GPT pro­gram* and dis­cuss the con­se­quences for the ma­chine pro­tec­tion sys­tem.
* www.pulsar.nl 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB142  
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TUPAB143 Dependence of LEReC Beam Energy Spread on Photocathode Laser Modulation laser, electron, impedance, flattop 1669
 
  • S. Seletskiy, M. Blaskiewicz, A.V. Fedotov, D. Kayran, J. Kewisch, M.G. Minty, B. Sheehy, Z. Zhao
    BNL, Upton, Long Island, New York, USA
  • B. Sheehy
    Sheehy Scientific Consulting, Wading River, New York, USA
  
  Pre­sent re­quire­ments to the pho­to­cath­ode DC gun of the low en­ergy RHIC elec­tron cool­ing (LEReC) pro­ject is to pro­duce 100 ps long bunch of elec­trons with 130 pC charge. The laser pulse of re­quired length will be pro­duced with the stack­ing of mul­ti­ple few pi­cosec­ond long sub-pulses. De­pend­ing on the choice of the laser sub-pulse length and on the rel­a­tive delay be­tween these sub-pulses one can ob­tain laser pulse with var­i­ous lon­gi­tu­di­nal in­ten­sity mod­u­la­tions. The lon­gi­tu­di­nal mod­u­la­tion of laser in­ten­sity cre­ates lon­gi­tu­di­nal mod­u­la­tion of elec­tron bunch charge. Such mod­u­la­tion is known to cause the growth of e-beam un­cor­re­lated en­ergy spread in pho­toin­jec­tors - the ef­fect we would like to avoid. In this paper we es­ti­mate growth of e-beam en­ergy spread due to its ini­tial den­sity mod­u­la­tion and set re­quire­ments to the max­i­mum al­low­able depth of lon­gi­tu­di­nal mod­u­la­tion of pho­to­cath­ode laser in­ten­sity.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB143  
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TUPVA059 Overcoming the Space Charge Limit: Development of an Electron Lens for SIS18 electron, ion, gun, injection 2211
 
  • D. Ondreka, P.J. Spiller
    GSI, Darmstadt, Germany
  • P. Apse-Apsitis
    Riga Technical University, Riga, Latvia
  • K. Schulte
    IAP, Frankfurt am Main, Germany
  
  The 'Fa­cil­ity for Anti-Pro­ton and Ion Re­search' (FAIR) presently under con­struc­tion will de­liver in­tense ion beams to its ex­per­i­men­tal users. The re­quested in­ten­si­ties re­quire fill­ing the ex­ist­ing syn­chro­tron SIS18, which serves as in­jec­tor to FAIR, up to the space charge (SC) limit. Op­er­a­tion under these con­di­tions is chal­leng­ing due to the large tune foot­print of the beam, de­mand­ing del­i­cate con­trol of ad­verse ef­fects caused by ma­chine im­per­fec­tions to avoid emit­tance growth and beam loss. To fa­cil­i­tate the high in­ten­sity op­er­a­tion, the in­stal­la­tion of an elec­tron lens for SC com­pen­sa­tion into SIS18 is fore­seen. This re­quires an elec­tron beam of a cur­rent of sev­eral am­peres with lon­gi­tu­di­nal and trans­verse dis­tri­b­u­tions matched to those of the ion beam dur­ing the cycle. The elec­tron beam needs to be RF mod­u­lated at a band­width of a few MHz with time vary­ing am­pli­tude rang­ing from DC to fully mod­u­lated, while the trans­verse size needs to be con­tin­u­ously adapted to the adi­a­bat­i­cally shrink­ing ion beam. This con­tri­bu­tion re­ports on the re­quire­ments on an elec­tron lens for SC com­pen­sa­tion in SIS18.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA059  
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TUPVA140 Space charge effects of catch-up collision in a CW double-pass proton linac simulation, linac, proton, cavity 2429
 
  • Y. Tao, K. Hwang, J. Qiang
    LBNL, Berkeley, California, USA
  
  Re­cir­cu­lat­ing su­per­con­duct­ing pro­ton linac has an ad­van­tage to re­duce the num­ber of cav­i­ties and the re­sult­ing ac­cel­er­a­tor con­struc­tion/op­er­a­tion costs. Beam dy­nam­ics sim­u­la­tions were done re­cently in a dou­ble pass re­cir­cu­lat­ing pro­ton linac using a sin­gle bunch. For con­tin­u­ous wave (CW) op­er­a­tion, the high en­ergy pro­ton beam bunch dur­ing the sec­ond pass will catch up and col­lide with the low en­ergy pro­ton bunch at a num­ber of lo­ca­tions in­side the su­per­con­duct­ing linac. In this paper, we re­port on the study of the space-charge ef­fects dur­ing a col­li­sion on both beams through the rest of the linac.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA140  
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WEXB1 Studies and Observations of Beam Dynamics Near a Sum Resonance resonance, synchrotron, emittance, simulation 2503
 
  • G. Franchetti
    GSI, Darmstadt, Germany
  • S.S. Gilardoni, A. Huschauer, F. Schmidt, R. Wasef
    CERN, Geneva, Switzerland
  
  The ef­fect of space charge on bunches stored for long term in a can be se­vere for beam sur­vival. This may be the case in pro­jects as SIS100 at GSI or LIU at CERN. In the past decade sys­tem­atic sim­u­la­tion stud­ies and ex­per­i­ments per­formed at CERN and GSI have high­lighted the space charge in­duced pe­ri­odic cross­ing of “one di­men­sional” res­o­nances as the un­der­ly­ing mech­a­nism of long term beam loss or emit­tance growth. How­ever only in 2012, for the first time, the ef­fect of space charge on a nor­mal third order cou­pled res­o­nance was in­ves­ti­gated at the CERN-PS. The ex­per­i­men­tal re­sults have high­lighted an un­prece­dented asym­met­ric beam re­sponse where in the hor­i­zon­tal plane the beam ex­hibits a thick halo, whereas the ver­ti­cal pro­file has only core growth. The quest for ex­plain­ing these re­sults re­quires a jour­ney thor­ough the 4 di­men­sional dy­nam­ics of the cou­pled res­o­nance in­ves­ti­gat­ing the fix-lines, and re­quires a de­tailed code-ex­per­i­ment bench­mark­ing also in­clud­ing beam pro­file bench­mark­ing. This study shows that the ex­per­i­men­tal re­sults of the 2012 PS mea­sure­ments can be ex­plained by the dy­nam­ics the fixed lines also in­clud­ing the ef­fect of the dis­per­sion.  
slides icon Slides WEXB1 [18.195 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEXB1  
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WEPAB031 OCELOT as a Framework for Beam Dynamics Simulations of X-Ray Sources simulation, wakefield, FEL, electron 2642
 
  • S.I. Tomin
    XFEL. EU, Hamburg, Germany
  • I.V. Agapov, M. Dohlus, I. Zagorodnov
    DESY, Hamburg, Germany
  
  We de­scribe the OCELOT open source pro­ject fo­cus­ing on new beam dy­nam­ics sim­u­la­tion ca­pa­bil­i­ties of the whole ma­chine in mod­ern elec­tron-based x-ray sources. Nu­mer­i­cal ap­proaches for par­ti­cle track­ing and field cal­cu­la­tions are dis­cussed. In de­vel­op­ing of the full-di­men­sional nu­mer­i­cal mod­el­ing we pur­sue two im­por­tant com­pet­i­tive as­pects: the sim­u­la­tion has to be fast and has to in­clude ac­cu­rate es­ti­ma­tions of col­lec­tive ef­fects. The sim­u­la­tion re­sults for the Eu­ro­pean XFEL [1] are pre­sented. The re­sults have been bench­marked agains other codes and some of such bench­marks are shown.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB031  
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WEPAB118 High Power Sub-Femtosecond X-Ray Pulse Study for the LCLS undulator, electron, simulation, photon 2848
 
  • J.P. MacArthur
    Stanford University, Stanford, California, USA
  • J.P. Duris, Z. Huang, A. Marinelli
    SLAC, Menlo Park, California, USA
  
  The de­sire to re­solve sub-fem­tosec­ond elec­tron dy­nam­ics has pushed FEL fa­cil­i­ties to shorter pulse lengths. How­ever, cur­rent short-pulse schemes pro­vide low pulse en­ergy and a gain-length lim­ited lower bound on the pulse du­ra­tion. The X-ray Laser-En­hanced At­tosec­ond Pulses (XLEAP) pro­ject at SLAC is de­signed im­ple­ment an En­hanced Self Am­pli­fied Spon­ta­neous Emis­sion (ESASE) scheme, which pro­duces sub-fs cur­rent spikes by mod­u­lat­ing and com­press­ing the elec­tron beam. We show through a se­ries of Gen­e­sis sim­u­la­tions that the cur­rent spike is ca­pa­ble of pro­duc­ing sub-fs pulses with a peak power well above 100 GW. Space-charge in­duced beam chirp can de­crease pulse lengths below 400 as, and multi-stage schemes can in­crease peak x-ray pow­ers to around 1 TW.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB118  
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WEPIK014 Coupled Bunch Instability and Its Cure at J-PARC RCS impedance, kicker, emittance, injection 2946
 
  • Y. Shobuda, H. Harada, H. Hotchi, P.K. Saha, T. Takayanagi, F. Tamura, N. Tani, T. Togashi, Y. Watanabe, K. Yamamoto, M. Yamamoto
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  • Y.H. Chin, Y. Irie, T. Toyama
    KEK, Ibaraki, Japan
  
  The RCS at J-PARC is a kicker-im­ped­ance dom­i­nant ma­chine, which vi­o­lates the im­ped­ance bud­get from a clas­si­cal view­point. Nev­er­the­less, we have re­cently suc­ceeded to ac­cel­er­ate a 1-MW equiv­a­lent beam by mak­ing max­i­mum use of the space charge ef­fect on the beam in­sta­bil­i­ties. In this re­port, we ex­plain the ma­nip­u­la­tion to sup­press the beam in­sta­bil­ity, at first. Then, we dis­cuss some is­sues to sup­press the beam in­sta­bil­i­ties for beams with much smaller trans­verse emit­tance, as well as the pre­sent sta­tus of our ef­forts to re­duce the kicker im­ped­ance to­ward the re­al­iza­tion of the higher beam power at the RCS.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK014  
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WEPIK074 Twiss Parameter Measurement and Application to Space Charge Dynamics resonance, betatron, emittance, lattice 3101
 
  • K. Ohmi, S. Igarashi, T. Toyama
    KEK, Ibaraki, Japan
  • H. Harada, S. Hatakeyama
    JAEA/J-PARC, Tokai-mura, Japan
  • N. Kuroo
    UTTAC, Tsukuba, Ibaraki, Japan
  • Y. Sato
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  • R. Tomás, A. Wegscheider
    CERN, Geneva, Switzerland
  
  We are look­ing for fea­si­ble and quan­ti­ta­tive method to eval­u­ate space charge in­duced beam loss in J-PARC MR. One pos­si­ble way is space charge sim­u­la­tion and the­ory based on mea­sured Twiss pa­ra­me­ter. Twiss pa­ra­me­ter mea­sure­ment using turn-by-turn mon­i­tors is pre­sented. Res­o­nance strengths of lat­tice mag­nets and space charge force are es­ti­mated by the mea­sured Twiss pa­ra­me­ters. Emit­tance growth and beam loss under the res­o­nance strengths are dis­cussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK074  
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WEPIK094 LEIR Impedance Model and Coherent Beam Instability Observations impedance, ion, injection, electron 3159
 
  • N. Biancacci, H. Bartosik, A. Huschauer, E. Métral, T.L. Rijoff, B. Salvant, R. Scrivens
    CERN, Geneva, Switzerland
  • M. Migliorati
    University of Rome La Sapienza, Rome, Italy
  
  The LEIR ma­chine is the first syn­chro­tron in the ion ac­cel­er­a­tion chain at CERN and it is re­spon­si­ble to de­liver high in­ten­sity ion beams to the LHC. Fol­low­ing the re­cent progress in the un­der­stand­ing of the in­ten­sity lim­i­ta­tions, de­tailed stud­ies of the ma­chine im­ped­ance started. In this work we de­scribe the pre­sent LEIR im­ped­ance model, de­tail­ing the con­tri­bu­tion to the total lon­gi­tu­di­nal and trans­verse im­ped­ance of sev­eral ma­chine el­e­ment. We then com­pare the ma­chine tune shift ver­sus in­ten­sity pre­dic­tions against mea­sure­ments at in­jec­tion en­ergy and sum­ma­rize the co­her­ent in­sta­bil­ity ob­ser­va­tions in ab­sence of trans­verse damper feed­back.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK094  
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WEPIK101 Novel Implementation of Quadrupole and Higher Order Fringe Fields to Accelerator Design quadrupole, multipole, sextupole, dipole 3184
 
  • B.D. Muratori
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  
  Until re­cently, in the ini­tial de­sign phase of any ac­cel­er­a­tor pro­ject, it was not pos­si­ble to have an ad­e­quate de­scrip­tion of quadru­pole and higher order mul­ti­pole fringe fields. We re­port on the lat­est de­vel­op­ments in an­a­lyt­i­cal fringe fields for mul­ti­poles, par­tic­u­larly for quadrupoles and sex­tupoles. We show how they can be used to im­prove ac­cel­er­a­tor codes and make them both faster and more pre­cise. We also show how the an­a­lyt­i­cal for­mu­lae for the fringe fields yield ex­pres­sions for both the scalar and vec­tor po­ten­tials in elec­tro­mag­net­ism. We con­clude by dis­cussing the ap­pli­ca­tion of both po­ten­tials to the de­sign of mul­ti­pole mag­nets as well as the im­ple­men­ta­tion of sym­plec­tic kick ap­prox­i­ma­tions for fringe fields in thin lens mod­els that could be used in ac­cel­er­a­tor codes.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK101  
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WEPVA037 Machine Development Studies in the CERN PS Booster, in 2016 injection, emittance, extraction, booster 3339
 
  • E. Benedetto, S.C.P. Albright, M.E. Angoletta, W. Bartmann, J.M. Belleman, A. Blas, M. Cieslak-Kowalska, G.P. Di Giovanni, A. Findlay, V. Forte, A. Garcia-Tabares, G. Guidoboni, S. Hancock, M. Jaussi, B. Mikulec, J.C. Molendijk, A. Oeftiger, T.L. Rijoff, F. Schmidt, P. Zisopoulos
    CERN, Geneva, Switzerland
  • M. Cieslak-Kowalska
    EPFL, Lausanne, Switzerland
  • P. Zisopoulos
    Uppsala University, Uppsala, Sweden
  
  The paper pre­sents the out­stand­ing stud­ies per­formed in 2016 in prepa­ra­tion of the PS Booster up­grade, within the LHC In­jec­tor Up­grade pro­ject (LIU), to pro­vide twice higher bright­ness and in­ten­sity to the High-Lu­mi­nos­ity LHC. Major changes in­clude the in­crease of in­jec­tion and ex­trac­tion en­ergy, the im­ple­men­ta­tion of a H− charge-ex­change in­jec­tion sys­tem, the re­place­ment of the pre­sent Main Power Sup­ply and the de­ploy­ment of a new RF sys­tem (and re­lated Low-Level), based on the Finemet tech­nol­ogy. Al­though the major im­prove­ments will be vis­i­ble only after the up­grade, the pre­sent ma­chine can al­ready ben­e­fit of the work done, in terms of bet­ter bright­ness, trans­mis­sion and im­proved re­pro­ducibil­ity of the pre­sent op­er­a­tional beams. Stud­ies ad­dress the space-charge lim­i­ta­tions at low en­ergy, for which a de­tailed op­tics model is needed and for which mit­i­ga­tion mea­sure­ments are under study, and the blow-up re­duc­tion at in­jec­tion in the down­stream ma­chine, for which the beams need care­ful prepa­ra­tion and trans­mis­sion. More­over they ad­dress the re­quire­ments and the re­li­a­bil­ity of new beam in­stru­men­ta­tion and hard­ware that is being in­stalled in view of LIU.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA037  
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WEPVA067 Preliminary Results on the Resonant Excitation of THz Wakefield in a Multi-Mode Dielectric Loaded Waveguide by Bunch Train electron, wakefield, radiation, experiment 3426
 
  • D. Wang, Y.-C. Du, W. Gai, W.-H. Huang, L. Niu, X.L. Su, C.-X. Tang, Q.L. Tian, L.X. Yan
    TUB, Beijing, People's Republic of China
  • S.P. Antipov
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • Y.F. Liang
    Tsinghua University, Beijing, People's Republic of China
  
  Funding: Work supported by the National Nature Science Foundation of China (NSFC Grants No.11475097) and the National Key Scientific Instrument and Equipment Development Project of China (Grants No. 2013YQ12034504)
We re­port the pre­lim­i­nary ex­per­i­men­tal re­sults on the res­o­nant ex­ci­ta­tion of THz wake­field in a multi-mode di­elec­tric loaded wave­guide (DLW) by elec­tron bunch train at the Ts­inghua Uni­ver­sity ac­cel­er­a­tor beam­line. The bunch train with cer­tain lon­gi­tu­di­nal pe­ri­od­ic­ity was gen­er­ated based on non­lin­ear lon­gi­tu­di­nal space charge os­cil­la­tion [1]. By pass­ing such bunch train through a multi-mode DLW, we ob­served se­lec­tive ex­ci­ta­tion of the fifth lon­gi­tu­di­nal mode (TM05 mode) was res­o­nantly ex­cited. Fu­ture ex­per­i­ment plan is to tune the bunch train in­ter­val with a chi­cane in the beam­line in order to se­lec­tively ex­cite ar­bi­trary mode for tun­able THz ra­di­a­tion source with multi-mode DLWs.
*wangdan16@mail.tsinghua.edu.cn
*yanlx@mail.tsinghua.edu.cn
 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA067  
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THOAA2 Research on Compensation of Superconducting Cavity Failures in C-ADS Injector-I FPGA, hardware, cavity, linac 3635
 
  • J.P. Dai, C. Meng, Y. Shao, Z. Xue, F. Yan
    IHEP, Beijing, People's Republic of China
  
  Funding: Work supported by Natural Science Foundation of China (11575216)
For the pro­ton ac­cel­er­a­tors such as the China Ac­cel­er­a­tor Dri­ven sub­crit­i­cal Sys­tem(C-ADS), it is es­sen­tial and dif­fi­cult to achieve ex­tremely high per­for­mance re­li­a­bil­ity re­quire­ment. In order to achieve this per­for­mance re­li­a­bil­ity re­quire­ment, in ad­di­tion to hard­ware im­prove­ment, a fail­ure tol­er­ant de­sign is manda­tory. A com­pen­sa­tion mech­a­nism to cope with hard­ware fail­ure, mainly RF fail­ures of su­per­con­duct­ing cav­i­ties, will be in place in order to main­tain the high up­time, short re­cov­ery time and ex­tremely low fre­quency of beam loss. This paper pro­poses an in­no­v­a­tive and chal­leng­ing way for com­pen­sa­tion and re­match of cav­ity fail­ure with the hard­ware im­ple­men­ta­tion of the scheme using fast elec­tronic de­vices and Field Pro­gram­ma­ble Gate Ar­rays (FPGAs). A method com­bined build­ing an equiv­a­lent model for the FPGA with an im­proved ge­netic al­go­rithm has been de­vel­oped. Re­sults based on the model and al­go­rithm are com­pared with TRACEWIN sim­u­la­tion to show the pre­ci­sion and cor­rect­ness of the mech­a­nism. 		 
slides icon Slides THOAA2 [2.414 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THOAA2  
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THPAB013 A Fast Particle Tracking Tool for the Simulation of Dielectric Laser Accelerators simulation, laser, GPU, plasma 3716
 
  • F. Mayet, R.W. Aßmann, U. Dorda, W. Kuropka
    DESY, Hamburg, Germany
  • W. Kuropka, F. Mayet
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  
  Funding: GBMF - Gordon and Betty Moore Foundation
In order to sim­u­late the beam dy­nam­ics in grat­ing based Di­elec­tric Laser Ac­cel­er­a­tors (DLA) fully self-con­sis­tent PIC codes are usu­ally em­ployed. These codes model the evo­lu­tion of both the elec­tro­mag­netic fields in­side a laser-dri­ven DLA and the beam phase space very ac­cu­rately. The main draw­back of these codes is that they are com­pu­ta­tion­ally very ex­pen­sive. While the sim­u­la­tion of a sin­gle DLA pe­riod is fea­si­ble with these codes, long multi-pe­riod struc­tures can­not be stud­ied with­out ac­cess to HPC clus­ters. We pre­sent a fast par­ti­cle track­ing tool for the sim­u­la­tion of long DLA struc­tures. DLA­Tracker is a par­al­lelized code based on the an­a­lyt­i­cal re­con­struc­tion of the in-chan­nel elec­tro­mag­netic fields and a Boris/Vay-type par­ti­cle pusher. It com­pu­ta­tional ker­nel is writ­ten in OpenCL and can run on both CPUs and GPUs. The main code is fol­low­ing a mod­u­lar ap­proach and is writ­ten in Python 2.7. This way the code can be eas­iliy ex­tended for dif­fer­ent use cases. In order to bench­mark the code, sim­u­la­tion re­sults are com­pared to re­sults ob­tained with the PIC code VSim 7.2. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB013  
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THPAB027 Symplectic Multi-Particle Tracking Using Cuda GPU, simulation, kicker, emittance 3756
 
  • Zh.C. Liu
    IHEP, Beijing, People's Republic of China
  • J. Qiang
    LBNL, Berkeley, California, USA
  
  Funding: Work supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 and the Ministry of Science and Technology of China under Grant No.2014CB845501.
The sym­plec­tic track­ing model can pre­serve phase space struc­ture and re­duce non-phys­i­cal ef­fects in long term sim­u­la­tion. Though this model is com­pu­ta­tion­ally ex­pen­sive, it is very suit­able for par­al­leliza­tion and can be ac­cel­er­ated sig­nif­i­cantly by using Graphic Pro­cess­ing Units (GPUs). Using a sin­gle GPU, the code achieves a speedup of more than 400 com­pared with the time on a sin­gle CPU core. It also shows good scal­a­bil­ity on a GPU clus­ter at Oak Ridge Lead­er­ship Com­put­ing Fa­cil­ity. In this paper, we re­port on the GPU code im­ple­ment, the per­for­mance test on both sin­gle-GPU and multi-GPU clus­ter, and an ap­pli­ca­tion of beam dy­nam­ics sim­u­la­tion. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB027  
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THPAB049 Progress in the Understanding of the Performance Limitations in the CERN Low Energy Ion Ring resonance, ion, sextupole, optics 3819
 
  • A. Huschauer, H. Bartosik, S. Hancock, V. Kain
    CERN, Geneva, Switzerland
  
  The per­for­mance of heavy ion beams in the CERN Low En­ergy Ion Ring is mainly lim­ited by beam loss oc­cur­ing dur­ing the ra­dio-fre­quency cap­ture and the first part of ac­cel­er­a­tion. Since Oc­to­ber 2015, the dri­ving mech­a­nism of these losses has been stud­ied in de­tail and an in­ter­play of di­rect space charge forces and ex­cited be­ta­tron res­o­nances was iden­ti­fied as the most plau­si­ble ex­pla­na­tion of the phe­nom­e­non. In this paper we sum­ma­rize the cur­rent un­der­stand­ing of the loss mech­a­nism by pre­sent­ing re­cent ex­per­i­men­tal and sim­u­la­tion stud­ies. We dis­cuss strate­gies to mit­i­gate beam loss and fur­ther im­prove the per­for­mance of the ac­cel­er­a­tor in the fu­ture.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB049  
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THPAB050 Simulations of Beam-Beam Interactions With RF-Track for the AWAKE Primary Beam Lines electron, proton, simulation, plasma 3823
 
  • J.S. Schmidt, A. Latina
    CERN, Geneva, Switzerland
  
  The AWAKE pro­ject at CERN will use a high-en­ergy pro­ton beam at 400 GeV/c to drive wake'elds in a plasma. The am­pli­tude of these wake'elds will be probed by in­ject­ing into the plasma a low-en­ergy elec­tron beam (10-20 MeV/c), which will be ac­cel­er­ated to sev­eral GeV. Up­stream of the plasma cell the two beams will ei­ther be trans­ported coax­i­ally or with an o'set of few mil­lime­tres for about 6 m. The in­ter­ac­tion be­tween the two beams in this beam line has been in­ves­ti­gated in the past, with a ded­i­cated sim­u­la­tion code track­ing par­ti­cles under the in'uence of di­rect space-charge e'ects. These sim­u­la­tions have re­cently been cross­checked with a new sim­u­la­tion code called RF-Track, de­vel­oped at CERN to sim­u­late low en­ergy ac­cel­er­a­tors. RF-Track can track mul­ti­ple-specie beams at ar­bi­trary en­er­gies, tak­ing into ac­count the full elec­tro­mag­netic par­ti­cle-to-par­ti­cle in­ter-ac­tion. For its char­ac­ter­is­tics RF-Track seems an ideal tool to study the AWAKE two-beam in­ter­ac­tion. The re­sults of these stud­ies are pre­sented in this paper and com­pared to the pre­vi­ous re­sults. The im­pli­ca­tions for the fa­cil­ity per­for­mance are dis­cussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB050  
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THPAB059 CSR and Space Charge Studies for the CLARA Phase 1 Beamline dipole, electron, simulation, linac 3851
 
  • B.S. Kyle, R.B. Appleby
    UMAN, Manchester, United Kingdom
  • J.K. Jones, P.H. Williams
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • M.J. de Loos, S.B. van der Geer
    Pulsar Physics, Eindhoven, The Netherlands
  
  The in­stal­la­tion of Phase 1 of CLARA, the UK's new FEL test fa­cil­ity, is cur­rently un­der­way at Dares­bury Lab­o­ra­tory. When com­pleted, it will be able to de­liver 45 MeV elec­tron beams to the pre-ex­ist­ing VELA beam­line, which runs par­al­lel. Phase 1 con­sists of a 10 Hz pho­to­cath­ode gun, a 2 m long S-band trav­el­ling wave linac, a spec­trom­e­ter line, and as­so­ci­ated op­tics and di­ag­nos­tics. A de­tailed study into the beam dy­nam­ics of the lat­tice is pre­sented, with a focus to­wards the ef­fects of space charge and co­her­ent syn­chro­tron ra­di­a­tion on the elec­tron bunch. Sim­u­la­tions dis­agreed with pre­dic­tions from a one-di­men­sional model of co­her­ent ra­di­a­tion, and this dis­agree­ment is be­lieved to be due to a vi­o­la­tion of the Der­benev cri­te­rion.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB059  
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THPAB081 The Effects of Space-Charge on the Dynamics of the Ion Booster in the Jefferson Lab EIC (JLEIC) booster, resonance, injection, emittance 3906
 
  • E.W. Nissen, S.A. Bogacz
    JLab, Newport News, Virginia, USA
  
  Funding: Notice: This manuscript has been authored by Jefferson Science Associates, LLC under Contract No. DE-AC05-06OR23177 with the U.S. Department of Energy.
Op­ti­miza­tion of the booster syn­chro­tron de­sign to op­er­ate in the ex­treme space-charge dom­i­nated regime is pro­posed. This study is mo­ti­vated by the ul­tra-high lu­mi­nos­ity promised by the JLEIC ac­cel­er­a­tor com­plex, which poses sev­eral beam dy­nam­ics and lat­tice de­sign chal­lenges for its in­di­vid­ual com­po­nents. We ex­am­ine the ef­fects of space charge on the dy­nam­ics of the booster syn­chro­tron for the pro­posed JLEIC elec­tron ion col­lider. This booster will in­ject and ac­cu­mu­late pro­tons and heavy ions at an en­ergy of 280 MeV and then en­gage in a process of ac­cel­er­a­tion and elec­tron cool­ing to bring it to its ex­trac­tion en­ergy of 8 GeV. This would then be sent into the ion col­lider ring part of JLEIC. In order to ex­am­ine the ef­fects of space charge on the dy­nam­ics of this process we use the soft­ware SYN­ER­GIA. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB081  
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THPVA004 Pushing the Space Charge Limit: Electron Lenses in High-Intensity Synchrotrons? electron, synchrotron, ion, resonance 4417
 
  • W.D. Stem, O. Boine-Frankenheim
    TEMF, TU Darmstadt, Darmstadt, Germany
  • O. Boine-Frankenheim
    GSI, Darmstadt, Germany
  
  Funding: Work is supported by BMBF contract FKZ:05P15RDRBA
Sev­eral ac­cel­er­a­tor pro­jects re­quire an in­crease in the num­ber of par­ti­cles per bunch, which is con­strained by the space charge limit. Above this limit the trans­verse space charge force in com­bi­na­tion with the lat­tice struc­ture causes beam qual­ity degra­da­tion and beam loss. Pro­posed de­vices to mit­i­gate this beam loss in ion beams are elec­tron lenses. An elec­tron lens im­parts a non­lin­ear, lo­cal­ized fo­cus­ing kick to coun­ter­act the (global) space-charge forces in the pri­mary beam. This ef­fort is met with many chal­lenges, in­clud­ing a re­duced dy­namic aper­ture (DA), res­o­nance cross­ing, and beam-beam align­ment. This con­tri­bu­tion pro­vides a de­tailed study of ide­al­ized elec­tron lens use in high-in­ten­sity par­ti­cle ac­cel­er­a­tors, in­clud­ing a com­par­i­son be­tween an­a­lyt­i­cal cal­cu­la­tions and py­OR­BIT par­ti­cle-in-cell (PIC) sim­u­la­tions. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA004  
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THPVA005 Investigation of Electron Beam Assisted Density Boosting in Plasma Traps Using the Example of a Gabor Plasma Lens electron, plasma, simulation, experiment 4421
 
  • C. Beberweil, M. Droba, S. Klaproth, O. Meusel, D. Noll, H. Podlech, K. Schulte, K.I. Thoma
    IAP, Frankfurt am Main, Germany
  • S. Gammino, D. Mascali
    INFN/LNS, Catania, Italy
  • L. Malferrari, A. Montanari, F. Odorici
    INFN-Bologna, Bologna, Italy
  
  Gabor lenses are plasma traps that can be used for fo­cus­ing an ion beam lin­early with­out aber­ra­tions* by the elec­tric field of a con­fined elec­tron cloud. They com­bine strong elec­tro­sta­tic fo­cus­ing with the pos­si­bil­ity of space charge com­pen­sa­tion and pro­vide an at­trac­tive al­ter­na­tive to con­ven­tional ion beam op­tics in a LEBT sec­tion. The fo­cus­ing per­for­mance strongly de­pends on the den­sity and dis­tri­b­u­tion of the en­closed elec­tron plasma*. As the Gabor lens is usu­ally op­er­ated close to the ion source, resid­ual gas ion­iza­tion is sup­posed to be the cen­tral elec­tron gen­er­a­tion mech­a­nism. An elec­tron source is in­tro­duced in order to in­ves­ti­gate the pos­si­bil­ity of boost­ing the elec­tron den­sity in plasma traps using the ex­am­ple of a Gabor lens. This way, a Gabor lens could be op­er­ated under XUHV con­di­tions, where resid­ual gas ion­iza­tion is sup­pressed. The par­ti­cle in cell code ben­der** was used to sim­u­late the in­jec­tion into the con­fin­ing fields of the space charge lens in dif­fer­ent geo­met­ri­cal con­fig­u­ra­tions and a pro­to­type ex­per­i­ment was con­structed con­sist­ing of a Gabor lens and an elec­tron source sys­tem. In this con­tri­bu­tion, sim­u­la­tions and mea­sure­ments will be pre­sented.
* Schulte, K., et al. Electron cloud dynamics in a Gabor space charge lens. 2012
** Noll, D., et al. The particle-in-cell code bender and its application to non-relativistic beam transport. 2015 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA005  
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THPVA019 Self-consistent Space Charge Tracking Method based on Lie Transform simulation, proton, sextupole, emittance 4454
 
  • E. Laface, J. F. Esteban Müller
    ESS, Lund, Sweden
  
  In this paper we pro­pose to de­scribe the self-force of a par­ti­cles beam, known as space charge, as an Hamil­to­nan term de­pen­dent on the dis­tri­b­u­tion of the par­ti­cles' co­or­di­nates: Hsc = Hsc(ρ(x,y,z)). This Hamil­ton­ian is then used, to­gether with the ki­netic com­po­nent Hk in a Lie trans­form to gen­er­ate a trans­port map by e-L:Hk +Hsc: where the Lie op­er­a­tor :Hk + Hsc: is de­fined ac­cord­ing to the Dragt's no­ta­tion [1]. Then the Lie trans­form is used to trans­port di­rectly the dis­tri­b­u­tion func­tion ρ(x, y, z) in a self-con­sis­tent it­er­a­tive al­go­rithm. The re­sult of this proof-of-con­cept idea is ver­i­fied on a drift space and on a FODO chan­nel and com­pared with a tra­di­tional multi-par­ti­cles sim­u­la­tion code.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA019  
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THPVA021 Dynamics of Spectator Particles in Space-Charge Fields of Mismatched Beams With Cross-Plane Coupling lattice, coupling, simulation, proton 4462
 
  • M. Holz, V.G. Ziemann
    Uppsala University, Uppsala, Sweden
  
  In ac­cel­er­a­tors with high beam power, even mod­er­ate beam losses must be avoided. These losses are due to par­ti­cles reach­ing large trans­verse am­pli­tudes that form a low den­sity halo or­bit­ing the beam core. To study the beam halo for­ma­tion, we place a spec­ta­tor par­ti­cle out­side the beam core and let it in­ter­act with the core's elec­tric field. The core, we model by a self-con­sis­tent trans­verse Gauss­ian beam in­clud­ing non-lin­ear space charge forces and cross-plane cou­pling.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA021  
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THPVA023 Studies of Longitudinal Beam Stability in CERN PS Booster After Upgrade impedance, simulation, emittance, injection 4469
 
  • D. Quartullo, S.C.P. Albright, E.N. Shaposhnikova
    CERN, Geneva, Switzerland
  
  The CERN PS Booster, com­prised of four su­per­posed rings, is the first syn­chro­tron in the LHC pro­ton in­jec­tion chain. In 2021, after major up­grades, the in­jec­tion and ex­trac­tion beam en­er­gies, as well as the ac­cel­er­a­tion rate, will be in­creased. The re­quired beam in­ten­si­ties should be a fac­tor of two higher for nom­i­nal LHC and fixed-tar­get beams, and the cur­rently used nar­row-band fer­rite sys­tems will be re­placed by broad-band Finemet cav­i­ties in all four rings. Fu­ture beam sta­bil­ity was in­ves­ti­gated using sim­u­la­tions with the Beam Lon­gi­tu­di­nal Dy­nam­ics (BLonD) code. The sim­u­la­tion re­sults for ex­ist­ing sit­u­a­tion were com­pared with beam mea­sure­ments and gave a good agree­ment. An ac­cu­rate im­ped­ance model, to­gether with a care­ful es­ti­ma­tion of the lon­gi­tu­di­nal space charge, was used in sim­u­la­tions of the fu­ture ac­cel­er­a­tion cycle in sin­gle and dou­ble RF, with phase and ra­dial loops and con­trolled lon­gi­tu­di­nal emit­tance blow-up. Since the beam is not ul­tra-rel­a­tivis­tic and fills the whole ring (h=1), the front and multi-turn back wakes were taken into ac­count, as well as the RF feed­backs which re­duce the ef­fect of the Finemet im­ped­ance at the rev­o­lu­tion fre­quency har­mon­ics.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA023  
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THPVA032 Space-Charge Simulation of Integrable Rapid Cycling Synchrotron lattice, sextupole, optics, resonance 4501
 
  • J.S. Eldred, A. Valishev
    Fermilab, Batavia, Illinois, USA
  
  In­te­grable op­tics is an in­no­va­tion in par­ti­cle ac­cel­er­a­tor de­sign that en­ables strong non­lin­ear fo­cus­ing with­out gen­er­at­ing para­met­ric res­o­nances. We use a Syn­er­gia space-charge sim­u­la­tion to in­ves­ti­gate the ap­pli­ca­tion of in­te­grable op­tics to a high-in­ten­sity hadron ring that could re­place the Fer­mi­lab Booster. We find that in­cor­po­rat­ing in­te­gra­bil­ity into the de­sign sup­presses the beam halo gen­er­ated by a mis­matched KV beam. Our in­te­grable rapid cy­cling syn­chro­tron (iRCS) de­sign in­cludes other fea­tures of mod­ern ring de­sign such as low mo­men­tum com­paction fac­tor and har­mon­i­cally can­cel­ing sex­tupoles. Ex­per­i­men­tal tests of high-in­ten­sity beams in in­te­grable lat­tices will take place over the next sev­eral years at the Fer­mi­lab In­te­grable Op­tics Test Ac­cel­er­a­tor (IOTA) and the Uni­ver­sity of Mary­land Elec­tron Ring (UMER).  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA032  
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THPVA037 Injection of a Self-Consistent Beam at the Spallation Neutron Source injection, simulation, closed-orbit, target 4516
 
  • J.A. Holmes, S.M. Cousineau, T.V. Gorlov, M.A. Plum
    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. This research was supported by the DOE Office of Science, Basic Energy Science.
We plan to demon­strate the in­jec­tion of a self-con­sis­tent beam into the Spal­la­tion Neu­tron Source (SNS). Self-con­sis­tent beams are de­fined to be el­lip­soidal dis­tri­b­u­tions with uni­form den­sity and to re­tain these prop­er­ties under all lin­ear trans­for­ma­tions. Self-con­sis­tent dis­tri­b­u­tions may gen­er­ate very lit­tle halo if re­al­ized in prac­tice. Some may also be ma­nip­u­lated to gen­er­ate flat beams. Self-con­sis­tent dis­tri­b­u­tions in­volve very spe­cial re­la­tion­ships be­tween the phase space co­or­di­nates, mak­ing them dif­fi­cult to re­al­ize ex­per­i­men­tally. One self-con­sis­tent dis­tri­b­u­tion, the 2D ro­tat­ing dis­tri­b­u­tion, can be painted into the SNS ring, with slight mod­i­fi­ca­tion of the lat­tice. How­ever, it is un­known how ro­bust self-con­sis­tent dis­tri­b­u­tions will be under real world trans­port in the pres­ence of non­lin­ear­i­ties and other col­lec­tive ef­fects. This paper stud­ies these is­sues and the mit­i­ga­tion of un­wanted ef­fects by ap­ply­ing re­al­is­tic de­tailed com­pu­ta­tional mod­els to the sim­u­la­tion of the in­jec­tion of ro­tat­ing beams into SNS. The re­sult is a fea­si­ble pre­scrip­tion for the in­jec­tion of a ro­tat­ing self-con­sis­tent dis­tri­b­u­tion into the SNS ring. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA037  
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THPVA086 Beam Dynamics Studies of an Accelerating Tube for 6 MeV Electron LINAC emittance, electron, simulation, linac 4657
 
  • S. Zarei
    Nuclear Science and Technology Research, InstituteRadiation Application School, Tehran, Iran
  • F. Abbasi
    Shahid Beheshti University, Tehran, Iran
  • S. Ahmadiannamin
    ILSF, Tehran, Iran
  • F. Ghasemi
    NSTRI, Tehran, Iran
  • M. Lamehi
    IPM, Tehran, Iran
  
  Side cou­pled stand­ing wave ac­cel­er­at­ing tubes are widely used in a low en­ergy lin­ear ac­cel­er­a­tor be­cause of rel­a­tively high ac­cel­er­at­ing gra­di­ent and low sen­si­tiv­ity to con­struc­tion tol­er­ances. The ef­fec­tive in­ter­ac­tion of par­ti­cles and elec­tro­mag­netic fields is im­por­tant for ac­cel­er­ate elec­trons to in­tended en­ergy with the great­est ef­fi­ciency and beam qual­ity out­put. In this paper, we pre­sent the beam dy­nam­ics of a 6 MeV Side cou­pled stand­ing wave ac­cel­er­at­ing tube using a space charge track­ing al­go­rithm (ASTRA). The de­signed ac­cel­er­at­ing tube that feeds by a max­i­mum power of 2.6 MW res­o­nant at fre­quency of 2998.5 MHz in pi/2 mode. 37.5 per­cent cap­ture ef­fi­ciency, 6.82 pi-mm-mrad hor­i­zon­tal emit­tance, 6.78 pi-mm-mrad ver­ti­cal emit­tance, 2.24 mm hor­i­zon­tal and ver­ti­cal beam size and 1079 keV en­ergy spread of the out­put beam have been de­ter­mined from the re­sults of beam dy­nam­ics stud­ies in ASTRA  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA086  
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