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space-charge

      
Paper Title Other Keywords Page
MOPKF017 New Simulations on Microbunching Instability at TTF2 cathode, simulation, linac, damping 339
 
  • Y. Kim, Y. Kim, D. Son
    CHEP, Daegu
  • K. Floettmann
    DESY, Hamburg
  Microbunching instability in the FEL driver linac can be induced by collective self-fields such as longitudinal space charge, coherent synchrotron radiation, and geometric wakefields. In this paper, we describe the first start-to-end simulations including all important collective self-fields from the cathode to the end of TTF2 linac with 1.5 million macroparticles.  
 
MOPKF018 Injector and Bunch Compressor for the European XFEL Project emittance, linac, gun, simulation 342
 
  • Y. Kim, Y. Kim, D. Son
    CHEP, Daegu
  • M. Dohlus, K. Floettmann, T. Limberg
    DESY, Hamburg
  For the proper operation of European XFEL project, we should supply high quality electron beams with low emittance, short bunch length, and low energy spread to a 200 m long undulator. In this paper, we describe the optimization and design concepts of the XFEL injector and bunch compressors to control the beam parameter dilution due to the microbunching instability and CSR.  
 
MOPKF044 Wake Fields Effects in the Photoinjector of the SPARC Project emittance, impedance, linac, optics 405
 
  • V. Fusco, M. Ferrario, B. Spataro
    INFN/LNF, Frascati (Roma)
  • M.  Migliorati, L. Palumbo
    Rome University La Sapienza, Roma
  When a bunch travels off axis across structures whose shape is not uniform, such as RF cavity or bellows, generates longitudinal and transverse wake fields. In addition transverse time dependent fields (like transverse RF components and wake fields ) may induce correlated slice centroids displacement, so that each slice centroid motion become affected also by space charge forces generated by the next slices. An evaluation of the emittance degradation and induced energy spread in the SPARC injector is performed with an improved version of the code Homdyn and the results are discussed. A comparison with other codes (ABCI, PARMELA 3D) to validate our model is also presented.  
 
MOPKF060 Space Charge Effects for the ERL Prototype at Daresbury Laboratory emittance, linac, quadrupole, focusing 446
 
  • B.D. Muratori, C. Gerth
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • N. Vinokurov
    BINP SB RAS, Novosibirsk
  Daresbury Laboratory is currently building an Energy Recovery Linac Prototype (ERLP) that will operate at a beam energy of 35 MeV. In this paper we examine the Space Charge effects on the beam dynamics in the ERLP injector line. This is done in two distinct ways. The first is based on an analytic formula derived by Vinokurov through the envelope equations and a Kapchinsky-Vladimirsky (KV) distribution. This formula gives a rough estimate of the space charge effects in the case that no quadrupoles or dipoles are present in the injector line. The second estimate is given by the multi-particle tracking code ASTRA for the whole injector line both with and without quadrupoles. Both methods are compared and are found to be in good agreement. Typical examples of injector lines are given together with specific calculations for the ERLP.  
 
MOPKF067 Comparison of Different Buncher Cavity Designs for the 4GLS ERLP gun, linac, higher-order-mode, emittance 467
 
  • E. Wooldridge, C.D. Beard, C. Gerth
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • A. Buechner
    FZR/FWFE, Dresden
  A DC photocathode gun is part of the injector of the Energy Recovery Linac Prototype (ERLP) currently built at Daresbury Laboratory. A buncher is required for the ERLP to decrease the bunch length off the gun. Three different single-cell cavity designs were investigated: The Cornell buncher, the Elbe Buncher and an EU cavity without Higher Order Mode (HOM) dampers. The properties of these cavities were studied with the computer codes CST's Microwave Studio and ASTRA. The fundamental frequency and field pattern was investigated in Microwave Studio. The EU cavity had to be scaled from 500MHz as the required frequency for the buncher is 1.3GHz. As the anticipated kinetic energy of the electron beam after the gun is about 350keV a particle tracking code including the space charge forces is mandatory to study the effect of the different buncher cavity designs on the beam dynamics. The particle tracking code ASTRA was used to study the performance of the bunchers for a variety of beam parameters. From these investigations it was found that the three bunchers produce very similar effects on the particle bunch.  
 
TUPLT003 Transfer Matrices for the Coupled Space Charge Dominated Six-dimensional Particle Motion lattice, storage-ring, coupling, electron 1135
 
  • D.K. Kalantaryan, Y.L. Martirosyan
    CANDLE, Yerevan
  In this paper we present exact analytical solutions for the particle motion in the six-dimensional phase space taking into account the space charge forces of fully linear coupled beam. The transfer matrices for the typical elements of magnetic lattice, such as drifts, cavities, quadrupole and dipole magnets have been obtained. The symplectic transfer matrices are used to develop a tracking program for the coupled betatron and synchro-betatron motion that enables the simulation of the tilted beam effects in circular accelerators.  
 
TUPLT026 High Current Ion Beams at Frankfurt University ion, electron, power-supply, plasma 1198
 
  • M. Droba, O. Meusel, U. Ratzinger, K. Volk
    IAP, Frankfurt-am-Main
  A new building for the physics faculty at the Goethe-University in Frankfurt is under construction including an experimental hall. The Institute of Applied Physics IAP has started development of a high current ion beam facility consisting of a high voltage terminal(150 kV,I_beam < 300 mA,H-,p,Bi+), a 10 MV linear rf accelerator and a high current storage ring for 150 keV beams. The 150 kV terminal equipment is already ordered while the subsequent units are in the design stage. The storage ring will use a stellarator-like magnetic configuration to allow for a high degree of space charge compensation by electrons. The facility will allow high current beam investigations as well as experiments in fields of plasma, nuclear and atomic physics.  
 
TUPLT029 Status of the Superconducting D+-CH-DTL Design for IFMIF rfq, quadrupole, simulation, linac 1207
 
  • A.C. Sauer, H. Deitinghoff, H. Klein, H. Liebermann, O. Meusel, H. Podlech, U. Ratzinger, R. Tiede
    IAP, Frankfurt-am-Main
  Within the IFMIF project (International Fusion Materials Irradiation Facility) a high current D+-linac operated in cw mode has to be developed. The acceleration of a 125 mA D+-beam from 0.1 MeV up to 40 MeV must be performed at an extremely low loss rate (0.1-0.2 microA/m). One optional layout of the acceleration facility consists of a high current ion source, low energy beam transport (LEBT), Radio-Frequency-Quadrupol (RFQ) followed by a superconducting H-type DTL. The matching of the beam between subsequent linac sections has to be carefully optimized to avoid an activation of the structures. Actual beam dynamics simulations for such a linac design including parameter errors of components are reported. Consequences for the LEBT- and RFQ-section are discussed.  
 
TUPLT045 Separatrix Formalism Applied to Linacs Accelerating Particles with Different Charge to Mass Ratio linac, acceleration, proton, simulation 1252
 
  • A. Bogdanov, R. Maier, Y. Senichev
    FZJ/IKP, Jülich
  We have developed separatrix formalism for superconducting linear accelerators. This method allows optimizing the quasi-synchronous velocity behavior along a linac. It gives a great advantage in acceleration of particles with different charge to mass ratio. In the article design optimization of structure supposed to accelerate different particles is presented. As an example for numerical simulation superconducting injector COSY is taken.  
 
TUPLT051 Beam Optical Design of a Multi Charge Ion Recirculator for Charge Breeders ion, optics, quadrupole, dipole 1267
 
  • R. Cee, W. Mittig, A.C.C. Villari
    GANIL, Caen
  Ions of high charge states as required for both stable and radioactive beams in order to optimally profit from the existing accelerating voltage can be produced by means of a charge breeder. However, the energy increase obtained is accompanied by an intensity decrease due to the low efficiency of the charge breeding process. With respect to the production of radioactive beams an enhancement of the breeding efficiency would be most desirable to avoid a high power primary beam as yet inevitable to counteract the loss in intensity. For this purpose the beam optics of an ion recirculation capable to separate the desired charge state and to reinject the remaining charge spectrum has been designed. The ions extracted from both sides of the charge breeder are focused by electrostatic quadrupole doublets and bent by two 180° dipole magnets. After one revolution the optics realises horizontally a (1:1) and vertically a (1:-1) point-to-point image independent from the charge state of the ions. The second order geometric aberrations as well as most of the chromatic aberrations vanish.  
 
TUPLT162 Computation of the Longitudinal Space Charge Effect in Photoinjectors simulation, linac, laser, bunching 1506
 
  • C. Limborg-Deprey, P. Emma, Z. Huang, J.J. Welch, J. Wu
    SLAC, Menlo Park, California
  The LCLS Photoinjector produces a 100A, 10 ps long electron bunch which is later compressed down to 100 fs to produce the peak current required for producing SASE radiation. SASE saturation will be reached in the LCLS only if the emittance and uncorrelated energy spread remain respectively below 1.2 mm.mrad and 5. 10-4. This high beam quality will not be met if the Longitudinal Space Charge (LSC) instability develops in the injector and gets amplified in the compressors. The Longitudinal Space Charge instability originates in the injector beamline, from an initial modulation of the current density. Numerical computations, performed with Multiparticle Space Charge tracking codes, showing the evolution of the longitudinal phase space along the LCLS Photoinjector beamline, are presented. Those results are compared with an analytical model for various regimes of energy and acceleration. This study justifies the necessity to insert a "laser heater" in the LCLS Photoinjector beamline to warm up the beam and thus prevent the amplification of the LSC instability in the compressors. Numerical calculations of the 'laser heater' performances are presented.  
 
TUPLT164 CEBAF Injector Achieved World's Best Beam Quality for Three Simultaneous Beams with a Wide Range of Bunch Charges laser, gun, electron, cathode 1512
 
  • R. Kazimi, K. Beard, F.J. Benesch, A. Freyberger, J.M. Grames, T. Hiatt, A. Hutton, G.A. Krafft, L. Merminga, M. Poelker, M. Spata, M. Tiefenback, B.C. Yunn, Y. Zhang
    Jefferson Lab, Newport News, Virginia
  The CEBAF accelerator simultaneously provides three 499 MHz interleaved continuous electron beams spanning 5 decades in beam intensity (a few nA to 200 uA) to three experimental halls. The typical three-user physics program became more challenging when a new experiment, G0, was approved for more than six times higher bunch charge than is routine. The G0 experiment requires up to 8 million electrons per bunch (at a reduced repetition rate of 31 MHz) while the lowest current hall operates at 100 electrons per bunch simultaneously. This means a bunch destined to one hall may experience significant space charge forces while the next bunch, for another hall, is well below the space charge limit. This disparity in beam intensity is to be attained while maintaining best ever values in the beam quality, including final relative energy spread (<2.5x 10-5 rms) and transverse emittance (<1 mm-mrad norm. rms). The difficulties related to space charge emerge in the 10m long, 100 keV section of the CEBAF injector during initial beam production and acceleration. A series of changes were introduced in the CEBAF injector to meet the new requirements, including changes in the injector setup, adding new magnets, replacing lasers used for the photocathode and modifying typical laser parameters, stabilizing RF systems, and changes to standard operating procedures. In this paper, we will discuss all these modifications in some detail including the excellent agreement between the experimental results and detailed simulations. We will also present some of our operational results.  
 
TUPLT165 A PARMELA Model of the CEBAF Injector valid over a Wide Range of Parameters simulation, laser, emittance, electron 1515
 
  • Y. Zhang, K. Beard, F.J. Benesch, Y.-C. Chao, A. Freyberger, J.M. Grames, R. Kazimi, G.A. Krafft, R. Li, L. Merminga, M. Poelker, M. Tiefenback, B.C. Yunn
    Jefferson Lab, Newport News, Virginia
  A pre-existing PARMELA model of the CEBAF injector has been recently verified using machine survey data and also extended to 60 MeV region. The initial distribution and temperature of an electron bunch are determined by the photocathode laser spot size and emittance measurements. The improved injector model has been used for extensive computer simulations of the simultaneous delivery of the Hall A beam required for a hypernuclear experiment, and the Hall C beam, required for a parity experiment. The Hall C beam requires a factor of 6 higher bunch charge than the Hall A beam, with significantly increased space charge effects, while the Hall A beam has an exceedingly stringent energy spread requirement of 2.5x 10-5 rms. Measurements of the beam properties of both beams at several energies (100 keV, 500 keV, 5 MeV, 60 MeV) and several values of the bunch charge were performed using the standard quad-wire scanner technique. Comparisons of simulated particle transmission rate, longitudinal beam size, transverse emittance and twiss parameters, and energy spread against experimental data yield reasonably good agreement. The model is being used for searching for optimal setting of the CEBAF injector.  
 
TUPLT166 Beam Invariants for Diagnostics diagnostics, beam-transport, quadrupole 1518
 
  • V.V. Danilov, A.V. Aleksandrov
    ORNL/SNS, Oak Ridge, Tennessee
  This paper deals with some measurable quantities of beams preserved under symplectic transformations. General beam distributions have no determined area, and rms quantities of the beam do not provide invariants in general nonlinear case. It is shown, though, that in the 1D case there exist some integral and local invariants, directly linked to Liouville's theorem. Beam invariants, related to general properties of symplectic transformations, are also found and presented for 2D and 3D cases. If measured at different locations, they can tell whether the transformation is symplectic or there exist diffusion, friction, or other non-Hamiltonian dynamic processes in the beam.  
 
TUPLT170 The SNS Beam Power Upgrade linac, extraction, kicker, klystron 1527
 
  • S. Henderson, S. Assadi, R. Cutler, V.V. Danilov, G.W. Dodson, R.E. Fuja, J. Galambos, J.A. Holmes, N. Holtkamp, D.-O. Jeon, S. Kim, L.V. Kravchuk, M.P. McCarthy, G.R. Murdoch, D.K. Olsen, T.J. Shea, M.P. Stockli
    ORNL/SNS, Oak Ridge, Tennessee
  The Spallation Neutron Source (SNS) accelerator systems, which consist of an H- injector, a 1 GeV linear accelerator, an accumulator ring and associated transport lines, will provide a 1 GeV, 1.44 MW proton beam to a liquid mercury target for neutron production. The SNS is presently under construction at Oak Ridge National Laboratory and will begin operations in 2006. Even in the baseline design, many of the accelerator subsystems are capable of supporting higher beam intensities and higher beam energy. We report on upgrade scenarios for the SNS accelerator systems which increase the 1.44 MW baseline beam power to at least 3 MW, and perhaps as high as 5 MW. The increased SNS beam power can be achieved primarily by increasing the H- ion source current, installing additional superconducting cryomodules to increase the final linac beam energy to 1.3-1.4 GeV, and modifying injection and extraction hardware in the ring to handle the increased beam energy. The upgrade beam parameters will be presented, the required hardware modifications will be described, and the beam dynamics implications will be discussed.  
 
TUPLT171 ORBIT Simulations of the SNS Accumulator Ring simulation, injection, electron, linac 1530
 
  • J.A. Holmes, S.C. Bunch, S.M. Cousineau, V.V. Danilov, S. Henderson, A. Shishlo
    ORNL/SNS, Oak Ridge, Tennessee
  • M. Plum
    LANL, Los Alamos, New Mexico
  • Y. Sato
    IUCF, Bloomington, Indiana
  As SNS undergoes construction, many detailed questions arise concerning strategies for commissioning and operating the accumulator ring. The ORBIT Code is proving to be an indispensible tool for addressing these questions and for providing guidance to the physicists and decision makers as operation draws near. This paper shows the application of ORBIT to a number of ring issues including exclusion of the HEBT RF cavities during commissioning, the detailed effect of the injection chicane magnets on the beam, the effects and correction of magnet alignment and multipole errors, debunching of the linac 402.5 MHz beam structure, the injection of self consistent uniform beam configurations, and initial electron cloud simulations.  
 
WEOALH01 Particle-in-cell Beam Dynamics Simulations simulation, electromagnetic-fields, damping, cathode 170
 
  • T. Lau, E. Gjonaj, T. Weiland
    TEMF, Darmstadt
  We describe the application of the Conformal Finite Integration Technique (CFIT) in the time-domain to beam dynamics simulations with the Particle-In-Cell (PIC) method. The conformal method results in a more accurate field solution for complicated geometries than the traditional FIT approach. For long-time simulations we investigate several methods for the suppression of the spurious noise, typically emerging in PIC simulations. The results are compared with the analytical solution for a bunch in a semi-infinite waveguide for each of the presented methods. As a realistic example simulations for the RF-Gun installed at Photo Injector Test Facility in DESY Zeuthen (PITZ) will be presented.  
Video of talk
Transparencies
 
WEYLH03 Collective Effects and Instabilities in Space Charge Dominated Beams resonance, simulation, electron, impedance 189
 
  • J.A. Holmes
    ORNL/SNS, Oak Ridge, Tennessee
  Significant progress in the detailed computational study of collective beam dynamics is being driven by the spectacular increase in computer power. To take advantage of this, sophisticated physics models are being applied to ever more realistic and detailed situations, so that it is no longer necessary to restrict computer studies to highly idealized depictions of beam dynamics questions. This presentation will illustrate the application of a number of collective beam dynamics models to a range of accelerator physics problems in high intensity proton rings. In particular, we will consider the effects of space charge, transverse and longitudinal impedances, and electron cloud formation on beam parameters, stability, halo formation, collimation and losses, and possible equilibrium configurations. Examples will be taken from PSR, the CERN PS Ring, and SNS.  
Video of talk
Transparencies
 
WEPLT008 Simulated Emittance Growth due to Electron Cloud for SPS and LHC emittance, electron, simulation, injection 1831
 
  • E. Benedetto, D. Schulte, F. Zimmermann
    CERN, Geneva
  • G. Rumolo
    GSI, Darmstadt
  The emittance growth caused by an electron cloud is simulated by the HEADTAIL code. The simulation result depends on the number of beam-cloud "interaction points"(IPs), the phase advance between the IPs, the number of macro-particles used to represent beam and cloud, and on the betatron tune. Simulations include a transverse feedback system and, optionally, a large chromaticity, as employed in actual SPS operation. Simulation results for the SPS are compared with observations, and the emittance growth in the LHC is computed as a function of the average electron density.  
 
WEPLT013 Investigation of Space Charge Effects and Intrabeam Scattering for Lead Ions in the SPS injection, proton, scattering, emittance 1846
 
  • H. Burkhardt, D. Manglunki, M. Martini, F. Roncarolo
    CERN, Geneva
  • G. Rumolo
    GSI, Darmstadt
  Space charge effects and intrabeam scattering usually play a minor role in high energy machines like the SPS. They can potentially become a limitation for the heavy ion beams needed for the LHC at the injection plateau in the SPS. Experimental studies on space charge limitations performed on low energy proton beams in the SPS will be described. Theoretical studies have been performed to predict emittance growth times due to intrabeam scattering using several different codes.  
 
WEPLT028 High-intensity and High-density Charge-exchange Injection Studies into the CERN PS Booster at Intermediate Energies injection, simulation, linac, emittance 1891
 
  • M. Martini
    CERN, Geneva
  • C.R. Prior
    CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon
  For the high brilliance LHC ultimate beam and the high intensity CNGS beam, single batch injections into the CERN Proton Synchrotron (PS) will be used to increase the overall machine intensity compared with the present double batch injections. Charge-exchange injection into the PS Booster with a new linac at intermediate energies is thus examined. A key parameter to consider is the energy dependence of beam incoherent tune shifts at injection. Increasing the linac energy from the present 50 MeV to 160 MeV should yield a safer tune shift. For each PS Booster ring, a charge-exchange injection scheme is envisaged inside a proper straight section, redesigned with new bends to make a local bump and using the existing fast bump magnets for horizontal phase-space painting. ACCSIM simulations for charge-exchange injection at 160 MeV have been investigated for both LHC and CNGS beams. After optimizing the parameters that are used for the space charge tracking routines, the results of the simulations agree well with expectations, signifying that the LHC ultimate and CNGS beams may be provided with single PS Booster batches within the required emittances. For assessment, simulation of injection at 50 MeV for the current LHC beam has been performed, yielding a fairly good agreement with measured performance. Concurrently, similar charge-exchange injection simulations have been carried out using an alternative programme developed at the Rutherford Appleton Laboratory.  
 
WEPLT030 Stability Diagrams for Landau Damping with Two-dimensional Betatron Tune Spread from Both Octupoles and Non-linear Space Charge applied to the LHC at Injection octupole, betatron, injection, damping 1897
 
  • E. Métral, F. Ruggiero
    CERN, Geneva
  The joint effect of space-charge non-linearities and octupole lenses is discussed for the case of a quasi-parabolic transverse distribution of a monochromatic beam. The self-consistent non-linear space-charge tune shift corresponding to the above distribution function is first derived analytically. The exact dispersion relation is also given but not solved. Instead, noting that a good approximation of the non-linear space-charge tune shift is obtained considering only linear terms in the action variables, the dispersion relation is solved analytically in this approximate case. As expected, in the absence of external (octupolar) non-linearities, the result of Möhl and Schönauer is recovered: there is no stability region. In the absence of space charge, the stability diagrams of Berg and Ruggiero are also recovered. Finally, the new result is applied to the LHC at injection.  
 
WEPLT047 A Test Suite of Space-charge Problems for Code Benchmarking simulation, focusing, proton, quadrupole 1942
 
  • A. Adelmann
    PSI, Villigen
  • J. Amundson, P. Spentzouris
    Fermilab, Batavia, Illinois
  • J. Qiang, R.D. Ryne
    LBNL/CBP, Berkeley, California
  A set of problems is presented for benchmarking beam dynamics codes with space charge. As examples, we show comparisons using the IMPACT, MaryLie/IMPACT, and MAD9P codes. The accuracy and convergence of the solutions as a function of solver algorithms, simulations parameters such as number of macro particles, grid size, etc. are studied.  
 
WEPLT048 Beam Dynamic Studies of the 72 MeV Beamline with a 'Super Buncher' cyclotron, simulation, transverse-dynamics, proton 1945
 
  • A. Adelmann, S. Adam, R. Dölling, M. Pedrozzi, J.-Y. Raguin, P. Schmelzbach
    PSI, Villigen
  A significant increase of the beam intensity increase of the PSI 590 MeV proton accelerator facility above 2 mA requires a higher accelerating voltage in the main RF cavities. A corresponding increase of the voltage in the flattop cavity would result in a complete rebuild of this device. As an alternative, a scheme with a strong buncher in the 72 MeV beam transfer line is being studied. The goal is to restore the narrow phase width (~ 2 deg/RF at 50 MHz) of the beam bunches observed at extraction from Injector 2 at injection into the Ring Cyclotron. If we can find and inject a stable particle distribution, as done in the Injector 2, the flat-top cavity might eventually be decommissioned. First results of multi particle tracking in full 6 dimensional phase space with space charge are presented.  
 
WEPLT053 Dynamical Effects of the Montague Resonance emittance, simulation, synchrotron, resonance 1960
 
  • I. Hofmann, G. Franchetti
    GSI, Darmstadt
  • J. Qiang, R.D. Ryne
    LBNL/CBP, Berkeley, California
  In high-intensity accelerators emittance coupling, known as Montague resonance, may be an issue if the tune split is small. For static tunes within the stop-band of this fourth order space charge driven coupling the final emittances may become equal (equipartition). Using 2D computer simulation we show, however, that slow crossing of the resonance leads to merely an exchange of emittances. In 3D this is similar, if the crossing occurs over a time-scale shorter or comparable with a synchrotron period. For much slower crossing we find, instead, that the exchange may be suppressed by synchrotron motion. We explain this effect in terms of the mixing caused by the synchrotron motion.  
 
WEPLT058 A Space Charge Algorithm for Ellipsoidal Bunches with Arbitrary Beam Size and Particle Distribution linac 1975
 
  • G. Franchetti, A. Orzhekovskaya
    GSI, Darmstadt
  For the GSI future project beam loss control of a high intensity bunched beam stored in SIS100 for 106 turns is an important issue. In a recent study (G. Franchetti et al., Phys. Rev. ST Accel. Beams 6, 124201 (2003)) an analytical space charge algorithm was proposed, which allowed noise-free calculations over a large number of turns. Here we present a generalization of this algorithm to arbitrary 3D dimensions and arbitrary distributions observing ellipsoidal symmetry. Applications to long-term tracking with space charge are presented  
 
WEPLT059 Beam Loss Modeling for the SIS100 beam-losses, resonance, lattice, synchrotron 1978
 
  • G. Franchetti, I. Hofmann
    GSI, Darmstadt
  In long term storage dynamic aperture is typically regarded as the quantity which has to be maintained sufficiently large in order to prevent beam loss. In the SIS100 of the GSI future project, a beam size occupying a large fraction of the beam pipe is foreseen. This circumstance requires a careful description of the lattice magnetic imperfections. The dynamic aperture is estimated in relation with an optimization of the SIS100 working point. For a space-charge-free bunched beam, estimates of beam loss are computed and compared with dynamic aperture. The impact of space charge will be discussed, and preliminary results on its effect on dynamic aperture and beam loss are presented.  
 
WEPLT060 Linear Coupling Theory of High Intensity Beams resonance, coupling, emittance, simulation 1981
 
  • G. Franchetti, I. Hofmann
    GSI, Darmstadt
  • M. Aslaninejad
    IPM, Tehran
  It is planned to use linear coupling in the SIS18 in order to fully or partially equilibrate the transverse emittances before transfer to the projected SIS100 synchrotron. In this paper we show that space charge significantly modifies the coupling mechanism. In particular the width of the stop-band is dominated by the space charge tune shift for weak skew strength. The conditions are discussed, under which slow crossing of the coupling resonance leads to the desired goal of equalizing emittances while maintaining a sufficient matching of the beam to the ring and extraction optics.  
 
WEPLT067 Space Charge Problem in Low Energy Super-conducting Accelerator focusing, linac, resonance, simulation 2002
 
  • N.E. Vasyukhin, R. Maier, Y. Senichev
    FZJ/IKP, Jülich
  At present the super-conducting option of linear accelerators is considered for low energy, and new type of RF cavities is considered for this purpose. However, together with electrodynamics problems we should solve the transverse stability problem, since in structures with external focusing elements the focusing period is longer, and in higher accelerating field the defocusing factor increases as well. In this paper we consider the transverse stability problem, taking into account the non-linear space charge problem. The fundamental mechanism of hallo creation in super-conducting linear accelerators is investigated to minimize the particle losses. The theoretical results are supported by numerical simulation.  
 
WEPLT078 The IFMIF High Energy Beam Transport Line target, linac, octupole, simulation 2032
 
  • D. Uriot, R. Duperrier, J. Payet
    CEA/DSM/DAPNIA, Gif-sur-Yvette
  The IFMIF project (International Fusion Materials Irradiation Facility) requests two linacs designed to accelerate 125 mA deuteron beams up to 40 MeV. The linac has to work in CW mode and uses one RFQ and 10 DTL tanks. After extraction and transport, the deuteron beams with strong internal space charge forces have to be bunched, accelerated and transported to target for the production of high neutron flux. This paper presents the high energy beam transport line which provides a flat rectangular beam profile on the liquid lithium target. Transverse uniformisation is obtained by using non-linear mutipole lenses (octupoles and duodecapoles). Beam dynamics with and without errors has been study.  
 
WEPLT086 Non Gaussien Transverse Distributions in a Stochastic Model for Beam Halos emittance, simulation, beam-losses, linac 2056
 
  • N. Cufaro Petroni
    INFN-Bari, Bari
  • S. De Martino, S. De Siena, F. Illuminati
    Universita' degli Studi di Salerno, Dipartimento di Fisica E.R. Caianiello, Baronissi
  The formation of the beam halo in charged particle accelerators is studied in a dynamical stochastic model for the collective motion of the particle beam. The density and the phase of the charged beam obey a set of coupled nonlinear hydrodynamic equations with time-reversal invariance. The linearized theory for this collective dynamics is given in terms of a classical Schroedinger equation. Self-consistent solutions with space-charge effects lead to quasi-stationary beam configurations with enhanced transverse dispersion and transverse emittance growth. In the limit of a frozen space-charge core it is possible to determine and study the properties of stationary, stable core-plus-halo beam distributions. We explore the effect of non-Gaussian transverse distributions. In this case the underling stochastic process is allowed to jump, and the transverse distribution tails are heavier than in the Gaussian case giving rise to a halo effect. The stationary transverse distribution plays the role of an attractor for every other distribution, and we give an estimation of the time needed by a non stationary, halo-free distribution to relax toward the stationary distribution with a halo.  
 
WEPLT107 Nonlinear field Effects in the JPARC Main Ring resonance, sextupole, injection, betatron 2101
 
  • A.Y. Molodojentsev, S. Machida, Y. Mori
    KEK, Ibaraki
  Main Ring (MR) of the Japanese Particle Accelerator Research Complex (JPARC) should provide acceleration of the high-intensity proton beam from the energy of 3GeV to 50 GeV. The expected beam intensity is 3.3·1014 ppp and the repetition rate is about 0.3 Hz. The imaginary transition lattice of the ring was adopted, which has the natural linear chromaticity about (-30) for both transverse phase planes. The expected momentum spread of the captured particles before the acceleration is less than 0.007. Two independent families of the chromatic sextupole magnets are use to eliminate the linear chromatic tune shift. This chromatic sextupole field nonlinearity will excite the normal 'octupole' resonances and will lead to the amplitude dependent tune shifts in both transverse phase planes. Additional sextupole magnets are planed to excite the third-order horizontal resonance, which will be used for the slow extraction. Incoherent tune shift of the low-energy proton beam is about (-0.16) so that some particles could cross nearest low-order resonances. Optimization of the 'bare' working point of MR at the injection energy has been performed to minimize the influence of the linear coupling and high-order coupling resonances. Excitation of the linear coupling resonance has been introduced by the realistic misalignment errors adopted for MR. The 'bare' working point during the slow extraction has been analyzed. The influence of the normal sextupole resonances on the large amplitude particle behavior at the scraper location has been studied including random sextupole field component of the MR bending magnets. Realistic distortion of the ideal ring super-periodicity by the injection kicker magnets has been included in the tracking procedure for the on- and off-momentum particles. Finally, correction schemes have been considered for most dangerous resonances around the optimized 'bare' working point. The space-charge effects of the proton beam have not been included in this study.  
 
WEPLT118 Performance of the TU/e 2.6 Cell Rf-photogun in the 'Pancake' Regime plasma, simulation, focusing, acceleration 2128
 
  • S.B. van der Geer, G.J.H. Brussaard, O.J. Luiten, M.J. Van der Wiel
    TUE, Eindhoven
  • G. Pöplau
    Rostock University, Faculty of Engineering, Rostock
  • M.J. de Loos
    PP, Soest
  The 2.6 cell rf-photogun currently in operation at Eindhoven University of Technology has been designed as a booster for a 2 MeV semi-DC accelerator with a field of 1 GV/m. In this paper we present GPT simulation results of the TU/e gun, operated without its pre-accelerator, in the low-charge short-pulse regime. The main part of the paper describes detailed calculations of bunch lengthening due to path-length differences and space-charge effects, making use of high-precision field-maps and the newly developed 3D mesh-based space-charge model of GPT. It is shown that with the present set-up bunches can be produced that are well suited for injection into a planned experiment for controlled acceleration in a plasma-wakefield accelerator.  
 
WEPLT152 Experimental Results of the Small Isochronous Ring simulation, cyclotron, diagnostics, ion 2194
 
  • J.A. Rodriguez, F. Marti, R.C. York
    NSCL, East Lansing, Michigan
  • E. Pozdeyev
    Jefferson Lab, Newport News, Virginia
  The Small Isochronous Ring (SIR) has been in operation since December 2003. The main purpose of this ring, developed and built at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University (MSU), is to simulate the dynamics of intense beams in large accelerators. To observe the same effects, the beam power needed in SIR is orders of magnitude lower and the time scale is much longer than in the full scale machines. These differences simplify the design and operation of the accelerator. The ring measurements can be used to validate the results of space charge codes. After a variable number of turns, the injected hydrogen bunch (with energies up to 30 keV) is extracted and its longitudinal profile is measured using a fast Faraday cup. We present a summary of the design, the results of the first six months of operation and the comparison with selected space charge codes.  
 
WEPLT154 UAL Implementation of String Space Charge Formalism emittance, lattice, synchrotron, quadrupole 2200
 
  • R.M. Talman
    Cornell University, Laboratory for Elementary-Particle Physics, Ithaca, New York
  • N. Malitsky
    BNL, Upton, Long Island, New York
  By reformulating the force between point charges as the force on a point charge due to a co-moving line charge (or "string",) space charge calculations can be reformulated as intrabeam scattering, with no intermediate, particle-in-cell step required.[*] This approach is expected to be especially useful for calculating emittance dilution of ultrashort bunches in magnetic fields, where coherent radiative effects are important. This paper describes the partial implementation of this approach within UAL (Unified Accelerator Libraries.) The interparticle force is calculated and applied to the dynamics of a bunch represented by just two superparticles in an idealized lattice, with emphasis on the head-tail effect. Gridding of the interparticle force, as needed for realistic multiparticle simulation, is also described.

* R. Talman, "String Formulation of Space Charge Forces in a Deflected Bunch". Submitted to PRSTAB, January, 2004

 
 
WEPLT168 ORBIT Benchmark of Space-charge-induced Emittance Growth in the CERN PS emittance, simulation, resonance, lattice 2221
 
  • S.M. Cousineau, J.A. Holmes
    ORNL/SNS, Oak Ridge, Tennessee
  • E. Métral
    CERN, Geneva
  Particle tracking codes provide an invaluable tool in the design and operation of high intensity machines. An important task in the development of these codes is the validation of the space charge models through benchmark with experimental data. Presented here are benchmarks of the ORBIT particle tracking code with recent measurements of space-charge-induced transverse emittance growth in the CERN PS machine. Benchmarks of two experimental data sets are performed: Integer resonance crossing, and Montague resonance crossing.  
 
WEPLT169 Benchmark and Threshold Analysis of Longitudinal Microwave Instability in the PSR injection, impedance, proton, storage-ring 2224
 
  • S.M. Cousineau, J.A. Holmes
    ORNL/SNS, Oak Ridge, Tennessee
  • C. Beltran, R.J. Macek
    LANL/LANSCE, Los Alamos, New Mexico
  A set of inductive inserts used to provide passive longitudinal space charge compensation in the Los Alamos Proton Storage Ring cause a strong microwave instability in the beam when the inductors are at room temperature. We use the ORBIT code to perform benchmarks of the microwave instability dynamics, including the mode spectrum and the instability growth time. Additionally, we analyze the experimental instability intensity threshold and compare it with the simulated threshold. For all parameters benchmarked, results of simulations are in good agreement with the experimental data.  
 
WEPLT170 Injection Schemes for Self Consistent Space Charge Distributions injection, closed-orbit, vacuum, betatron 2227
 
  • V.V. Danilov, S.M. Cousineau, S. Henderson, J.A. Holmes, M. Plum
    ORNL/SNS, Oak Ridge, Tennessee
  This paper is based on recently found sets of self-consistent 2D and 3D time-dependent space charge distributions. A subset of these distributions can be injection-painted into an accumulator ring, such as Spallation Neutron Source Ring, to produce periodic space charge conditions. The periodic condition guarantees zero space-charge-induced halo growth and beam loss during injection. Practical aspects of such schemes are discussed, and simulations of a few specific cases are presented.  
 
WEPLT183 Clearing of Electron Cloud in SNS electron, extraction, proton, ion 2248
 
  • L. Wang, Y.Y. Lee, D. Raparia, J. Wei, S.Y. Zhang
    BNL, Upton, Long Island, New York
  In this paper we describe a mechanism using the clearing electrodes to remove the electron cloud in the Spallation Neutron Source (SNS) accumulator ring, where strong multipacting could happen at median clearing fields. A similar phenomenon was reported in an experimental study at Los Alamos laboratory's Proton Synchrotron Ring (PSR). We also investigated the effectiveness of the solenoid's clearing mechanism in the SNS, which differs from the short bunch case, such as in B-factories.  
 
THOALH03 The Measurements of the Longitudinal Beam Profile on the Preinjector VEPP-5 electron, radiation, single-bunch, linac 259
 
  • S. Gurov, P.A. Bak, P.V. Logatchev, V. Pavlov, E. Pyata
    BINP SB RAS, Novosibirsk
  • D. Chernousov
    ICKC, Novosibirsk
  For effective work of preinjector VEPP-5 it is necessary 3 ns bunch with charge 1* 1010 electrons from termogun compress to bunch with 40 ps duration on the positron target. A new streak-camera with RF cavity on the main linac frequency is used. Streak-camera with circle scanning allows see 350 ps single light signal with sub-ps resolution. An additional slow scanning can obtain the trochoidal scanning. Thus one can see with picosecond resolution and with less then 1 psec synchronization the train of ten bunches which are spacing by 350psec. The results of worked streak-camera with RF-cavity for circle scanning are presented.  
Video of talk
Transparencies
 
THPLT030 A Novel Device for Non-intersecting Bunch Shape Measurement at the High Current GSI-Linac electron, background, linac, ion 2541
 
  • P. Forck, C. Dorn, M.H. Herty, P. Strehl
    GSI, Darmstadt
  • V. Peplov
    RAS/INR, Moscow
  • S. Sharamentov
    ANL, Argonne, Illinois
  Due to the high current of heavy ions accelerated at the UNILAC at GSI, non-intersecting beam diagnostics are mandatory. For bunch length and bunch structure determination in the range of 0.3 to 5 ns a novel device has been realized. It uses the time spectrum of secondary electrons created by atomic collisions between beam ions and residual gas molecules. These electrons are accelerated by an electric field of 400 V/mm toward an electro-static energy analyzer. The analyzer is used to restrict of the effective source region. Then the electrons are deflected by an rf-resonator running in phase with the acceleration frequency (36 or 108 MHz) to transform the time spectrum into spatial separation. The detection is done with a multi-channel plate equipped with a phosphor screen and observed by a digital CCD camera. The achieved time resolution is at least 50 ps, corresponding to 2 degree of rf frequency. The general layout of the device and first results will be presented.  
 
THPLT034 Implementation of Higher Order Moments for Beam Dynamics Simulation with the V-Code simulation, gun, emittance, laser 2553
 
  • W. Ackermann, T. Weiland
    TEMF, Darmstadt
  Based on the moment approach V-Code is implemented to simulate charged particle beam dynamics in linear accelerators. Its main aim is to perform elementary studies in those cases when the beam can be considered as a whole and thus making the motion of individual particles negligible in the overall view. Therefore an ensemble of particles can be well described by the moments of its phase-space distribution and the regarded order influences naturally the achievable accuracy as well as the computational effort. Since the well known moment equations generally are not closed, a technique to limit the number of involved moments has to be applied. So far all moments up to the second order have been considered whereas higher order moments are truncated. As a further step towards higher accuracy the influence of higher order moments has to be investigated. For this reason additional third-order equations are implemented into the V-Code and the achieved results are compared with previous second-order-based ones as well as with higher order approximations.  
 
THPLT035 Development of a 3D-Gun-Code based on a Charge Conserving Algorithm simulation, electron, cathode, gun 2556
 
  • E. Gjonaj, J. Mudiganti, T. Weiland
    TEMF, Darmstadt
  Recent efforts in the development of electron sources are aiming at high intensity electron beams, beyond the limitations posed by space-charge effects in conventional guns. Field emitter arrays, multi-beam and sheet-beam guns are a few examples of emerging technology, which require an accurate characterization of the limiting current in complicated 3D-geometry. The newly developed gun code at the Technische Universität Darmstadt, implements a novel approach to the numerical simulation of space-charge-limited electron emission, which is based on the local conservation of charge for arbitrary cathode surfaces. It is shown that, imposing exact charge conservation using the CAD-data of the geometry eliminates the spurious oscillations in the charge density, which typically arise when the piecewise-planar diode approximation is applied in the simulation. The accuracy of this approach is demonstrated in the validation study of a spherical diode and in the large-scale simulation of a Traveling Wave Tube amplifier.  
 
THPLT037 Investigation of Numerical Noise in PIC-Codes simulation, accumulation, emittance, focusing 2562
 
  • S. Schnepp, S. Setzer, T. Weiland
    TEMF, Darmstadt
  For a detailed analysis of the dynamics of space charge dominated beams a combination of Particle-in-Cell methods with efficient FDTD schemes is widely used. Besides the calculation of the forces acting on the particles the interaction of the beam itself with the surrounding geometries is taken into account. A drawback of this method is its sensitivity to numerical noise in the spectral range nearby the grid cutoff frequency. In this paper we will present results of detailed studies of the impact of the bunch shape on the level of the numerical noise. Furthermore an a priori scheme for efficient noise suppression is derived which does not affect the FDTD update algorithm.  
 
THPLT048 Progress in 3D Space-charge Calculations in the GPT Code acceleration, brightness, electron, emittance 2592
 
  • G. Pöplau, U. Van Rienen
    Rostock University, Faculty of Engineering, Rostock
  • M.J. de Loos
    PP, Soest
  • S.B. van der Geer
    TUE, Eindhoven
  The mesh-based 3D space-charge routine in the GPT (General Particle Tracer, Pulsar Physics) code scales linearly with the number of particles in terms of CPU time and allows a million particles to be tracked on a normal PC. The crucial ingredient of the routine is a non-equidistant multi-grid Poisson solver to calculate the electrostatic potential in the rest frame of the bunch. The solver has been optimized for very high and very low aspect ratio bunches present in state-of-the-art high-brightness electron accelerators. In this paper, we explore the efficiency and accuracy of the calculations as function of meshing strategy and boundary conditions.  
 
THPLT054 Emittance Diluition due to 3D Perturbations in RF Photoinjectors. emittance, cathode, focusing, extraction 2607
 
  • M. Quattromini, L. Giannessi, C. Ronsivalle
    ENEA C.R. Frascati, Frascati (Roma)
  The predictions from different simulation codes are compared to investigate the effects of non axis-symmetric conditions, fluctuations in cathode's quantum efficiency and other sources of dishomogeneities in the performances of a typical RF photoinjector. The layout includes a RF gun and a focusing solenoid in a configuration aimed at minimizing the emittance growth due to space charge effects.  
 
THPLT059 Design Study of a Movable Emittance Meter Device for the SPARC Photoinjector emittance, simulation, cathode, radiation 2622
 
  • A. Cianchi, L. Catani
    INFN-Roma II, Roma
  • M. Boscolo, M. Castellano, A. Clozza, G. Di Pirro, M. Ferrario, D. Filippetto, V. Fusco
    INFN/LNF, Frascati (Roma)
  • L. Giannessi, L. Picardi, M. Quattromini, C. Ronsivalle
    ENEA C.R. Frascati, Frascati (Roma)
  Preliminary studies of the SPARC rf gun are planned to obtain an accurate analysis and optimization of the emittance compensation scheme, measuring the beam emittance evolution downstream the RF gun with an appropriate diagnostic system. Since with a space charge dominated beam the use of the quad-scan method is not possible a 1D pepper-pot method will be used. A mask with narrow slits will be mounted on a movable support, spanning a 1.5 m meters region to measure the emittance in several positions and reconstruct its behavior in the post gun section. Numerical simulations of the measurement process, mainly based on PARMELA and TREDI, are used to estimate the achievable accuracy and to optimize the experimental setup. Wake field effects induced by the beam propagation through the long bellows have been also investigated with HOMDYN. Based on these simulations the design of the apparatus, called emittance-meter, has been realized and is under construction at LNF.  
 
THPLT071 Upgraded Symplectic 3D Beam Tracking of the J-PARC 3 GeV RCS injection, quadrupole, emittance, simulation 2658
 
  • M.J. Shirakata, H. Fujimori, Y. Irie
    KEK, Ibaraki
  The J-PARC 3 GeV ring is a rapid cycling synchrotron which consists of the large bore size magnets. The beam tracking with the 3D distributed magnetic fields is kept developing in order to investigate the beam injection process. In the case of the high intensity hadron accelerator, an accurate beam simulation is important for the designing because a very small amount of beam loss can be critical from the maintenance point of view. In order to improve the tracking accuracy and to save the calculation time, the symplectic integration with the fractal decomposition method has been introduced. The updated simulation results of the beam injection on the J-PARC 3 GeV RCS and the improved performance of ‘GenericSolver' are presented in this paper. The quadrupole fields are also treated as the 3D distributed magnetic fields because they interfered with the bump magnet fields. The remarkable features on the large bore magnet system in the ring accelerator are also discussed.  
 
THPLT082 Beam Diagnostics for a Photocathode Rf-gun System emittance, laser, electron, simulation 2688
 
  • K. Sakaue, N. Kudo, R. Kuroda, M. Washio
    RISE, Tokyo
  • H. Hayano, J. Urakawa
    KEK, Ibaraki
  • S. Kashiwagi
    ISIR, Osaka
  Beam diagnostic systems for high quality electron beam emitted from photo-cathode rf gun have been developed. Beam characteristics such as bunch length and emittance measurements were performed at Waseda University. The bunch length was measured using an rms bunch length monitor based on beam spectrum analysis. The monitor is very useful as the non-destructive and conventional tool even for the relatively low energy electron beam around 5MeV. The measurement results of the rms bunch lengths using this monitor are in good agreement with the simulation results of PARMELA. However, it is not applicable for the measurement of longitudinal profile of the electron bunch, so that we have started the manufacturing of a deflection cavity, so-called RF-Kicker, to measure the longitudinal profiles of the bunch. The emittance has been measured by using a slit scan technique. By using double slit scan technique, emittance of 9mmmrad has been obtained. Though the value is not satisfactory small, we believe that much smaller emittance can be obtained by optimizing a laser profile. The measurement results and progress of rf gun at Waseda University will be presented at the conference.  
 
THPLT099 The Analysis of the Electron Beam Scanning Method for the Beam Profile Monitoring. electron, ion, scattering, injection 2721
 
  • D.A. Liakin
    ITEP, Moscow
  The method of the beam profile monitoring with scanning electron beam is analyzed. Simulation model of the ion/electron beam interaction is presented and some simulation results are shown. In the report the estimation of overall performance characteristics of this method such as sensitivity, spatial resolution, frequency bandwidth etc. are given.  
 
THPLT146 Beam Diagnostics of the Small Isochronous Ring injection, diagnostics, emittance, extraction 2798
 
  • J.A. Rodriguez, F. Marti
    NSCL, East Lansing, Michigan
  • E. Pozdeyev
    Jefferson Lab, Newport News, Virginia
  The purpose of this paper is to describe the beam diagnostic systems in the Small Isochronous Ring (SIR) developed and built at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University (MSU). SIR is a small-scale experiment that simulates the dynamics of intense beams in large accelerators. A 20 to 30 keV hydrogen or deuterium ion bunch is injected in the ring, extracted after a variable number of turns and its longitudinal profile is studied. Some of the diagnostic tools available in SIR include an emittance measurement system in the injection line, scanning wires in different sections of the ring, phosphor screens at the injection and extraction points and a fast Faraday cup in the extraction line. The design of these systems and the kind of beam information they provide are discussed in detail.  
 
THPLT177 Maps for Fast Electron Cloud Simulations at RHIC electron, simulation, luminosity, proton 2870
 
  • U. Iriso, S. Peggs
    BNL, Upton, Long Island, New York
  Luminosity in several colliders, including RHIC, is limited by the electron cloud effect. A careful re-distribution of the bunch pattern around the azimuth of a ring can decrease the average electron density for a fixed total bunch current, allowing the luminosity to be increased. In the search for a bunch pattern that maximizes the luminosity, a fast computer simulation is a key requirement. We discuss the use of fast polynomial maps to simulate the bunch to bunch evolution of the electron density at RHIC. Such maps are empirically derived from existing conventional slow simulation codes.  
 
THPLT179 MADX-UAL Suite for Off-line Accelerator Design and Simulation simulation, quadrupole, sextupole, optics 2873
 
  • N. Malitsky, R.P. Fliller III, F.C. Pilat, V. Ptitsyn, S. Tepikian, J. Wei
    BNL, Upton, Long Island, New York
  • F. Schmidt
    CERN, Geneva
  • R.M. Talman
    Cornell University, Laboratory for Elementary-Particle Physics, Ithaca, New York
  We present here an accelerator modeling suite that integrates the capability of MADX and UAL packages, based on the Standard eXchange Format (SXF) interface. The resulting environment introduces a one-stop collection of accelerator applications ranging from the lattice design to complex beam dynamics studies. The extended capabilities of the MADX-UAL integrated approach have been tested and effectively used in two accelerator projects: RHIC, where direct comparison of operational and simulated data is possible, and the SNS Accumulator Ring, still in its design phase.