Keyword: space-charge
Paper Title Other Keywords Page
MOPEA037 Theoretical Study on the Two-stage Collimation System Design collimation, scattering, vacuum, simulation 157
 
  • N. Wang, S. Wang
    IHEP, Beijing, People's Republic of China
  
  Two-stage collimation system is widely used in high intensity machines to localize the beam losses in a restricted area. In the well-known theory, the optical constrains are expressed by the betatronic phase advances between primary and secondary collimators, which minimize the size of the secondary halo. In this paper, the physical model is developed considering the characteristic of the space charge dominated beams. Numerical studied are performed to verify the theoretical model.  
 
MOPFI028 Physical Design Progress of an 800 MeV High Power Proton Driver extraction, cyclotron, injection, acceleration 342
 
  • J.J. Yang, Shizhong. An, M. Li, T.J. Zhang, J.Q. Zhong
    CIAE, Beijing, People's Republic of China
  
  We presented the conceptual design of an 800 MeV high power proton ring cyclotron in the paper[1] . A more detailed physical design was carried out since then. The most challenging issues regarding the high power operation, including the space charge effects and beam loss during the extraction, are quantitatively studied by using state-of-the-art high performance computation technique. On that basis the fundamental structure of the cyclotron is adjusted and optimized so as to meet the requirements of MW-class operation. Reference: [1] T. Zhang, J. Yang, M. Li, et. al., Conceptual design of an 800 MeV high power proton driver, Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 269(24) (2011) 2964-2967  
 
MOPFI039 The Design of a Compact THz Source Based on Photocathode RF Gun electron, radiation, gun, emittance 375
 
  • W.W. Li, Z.G. He, R. Huang, Q.K. Jia
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  
  Narrow-band THz coherent Cherenkov radiation can be driven by a subpicosecond electron bunch traveling along the axis of a hollow cylindrical dielectric-lined waveguide. We present a scheme of compact THz radiation source based on the photocathode rf gun. On the basis of our analytic result, the subpicosecond electron bunch with high charge (800pC) can be generated directly in the photocathode rf gun. A narrow emission spectrum peaked at 0.24 THz with 2 megawatt (MW) peak power is expected to gain in the proposed scheme (the length of the facility is about 1.2 m), according to the analytical and simulated results.  
 
MOPME020 Development of the New Measurement Method for the Incoherent Tune Spread and the Tune Shift Caused by the Space Charge Effect dipole, emittance, simulation, injection 512
 
  • S. Kato
    Tohoku University, Graduate School of Science, Sendai, Japan
  • H. Harada, H. Hotchi, M. Kinsho, K. Okabe
    JAEA/J-PARC, Tokai-mura, Japan
  
  For the high intensity accelerator, the incoherent tune which is the frequency of the individual particles is shifted and decreases due to the space charge effect. In addition, the incoherent tune is formed into spread shape commonly. When the incoherent tune satisfies a resonance condition, it might be occurred the beam emittance growth and the beam loss. So it is necessary to reduce the incoherent tune spread and the tune shift as much as possible. To achieve this condition, it is desired to measure the incoherent tune spread and the tune shift directly. Therefore we are developing the new measurement method of the incoherent tune spread and the shift due to the space charge effect. From the simulation results, it was cleared that the beam distribution can be modified in the case of using the mono frequency dipole exciter because a particle which has the tune corresponding to the exciter can be resonated temporary. In addition, it was cleared that it is possible to evaluate the incoherent tune spread and the tune shift by the measurement of the distribution transition. We present the outline of this method and the developing plane at the J-PARC RCS.  
 
MOPWA034 Electron Tracking Simulations in the Presence of the Beam and External Fields emittance, electron, simulation, proton 741
 
  • M. Patecki, B. Dehning, G. Iadarola, M. Sapinski
    CERN, Geneva, Switzerland
  
  The ionisation profile monitors installed in the CERN LHC and SPS, makes use of the ionisation of small quantities of injected neon gas by the circulating beam. The electrons produced are guided towards the readout system using a combination of electric and magnetic fields. However, in the presence of the beam field their tracks are modified and the resulting profile is distorted. The Geant4 physics simulation package has been used to simulate the ionisation process, while the CERN-developed PyECLOUD code has been used for tracking the resulting ionised particles. In this paper the results of simulations are compared with observations, with conclusions presented on the accuracy of the reconstruction of high-intensity beam profiles.  
 
MOPWA061 A New Tool for Longitudinal Tomography in Fermilab's Main Injector and Recycler Rings booster, controls, injection, emittance 816
 
  • N.J. Evans, S.E. Kopp
    The University of Texas at Austin, Austin, Texas, USA
  • P. Adamson, D.J. Scott
    Fermilab, Batavia, USA
  
  Funding: U.S Department of Energy
We are developing software to compute tomographic reconstructions of longitudinal phase space distributions in the Fermi National Accelerator Laboratory Main Injector and Recycler rings using data from existing resistive wall current monitors to diagnose beam quality at injection and provide input distributions for simulation of losses. Building on the algorithm developed by *S. Hancock et al. at CERN the software is able to process a full synchrotron period of a Booster batch of 81 bunches with 18.94 ns spacing and a sampling rate of 2.5 GHz, in < 30 sec, or every ~270 injections. Processing an entire injection opens up the possibility of investigating coupled bunch instabilities via tomography. To speed reconstruction for use on a full injection, phase space maps are created once for a given set of parameters and saved for injections with similar machine settings. We present an overview of the system and studies done on the effect of small errors present including: random noise, mismatch between sampling rate and machine period, errors in locating bunch centers, and trigger jitter.
*Tomographic Measurements of Longitudinal Phase Space Density; 1998 ed. - Hancock, S et al - CERN-PS-98-030-RF 		 
 
MOPWO002 PTCC: New Beam Dynamics Design Code for Linear Accelerators linac, simulation, plasma, cavity 882
 
  • Y. N. Nour El-Din, T.M. Abuelfadl
    Cairo University, Giza, Egypt
  
  Funding: Work supported by the Egyptian Science and Technology Development Fund (STDF) No. 953.
A fast and accurate beam dynamics design code, named PTCC (Particle Tracking Code in C) is developed to simulate particles dynamic in linear accelerators. PTCC solves the relativistic equations of motion for the macro-particles when subjected to electromagnetic fields excited in RF cavities. The self-fields of the particles are also part of the electromagnetic fields through which the particles are tracked. Self-fields are calculated using a modified 2D cylindrically symmetric mesh based method, making use of beam and field symmetry to provide fast simulation. The code has been benchmarked with the well known code ASTRA which is used mainly in simulations of next generation FEL linacs. PTCC provides a new tool for designing buncher section of linear accelerators that convert DC beam into bunches. New buncher design tool and benchmark results of PTCC with ASTRA are presented. 		 
 
MOPWO013 A New Scalable Software Package for Large Scale Beam Dynamic Simulations simulation, target, DTL, solenoid 912
 
  • R. Zhao, J. Xu
    IS, Beijing, People's Republic of China
  • Y. He, C. Li, X. Qi, L. Yang
    IMP, Lanzhou, People's Republic of China
  
  Large scale Beam Dynamics Simulations (BDS) are important in accelerator design and optimization. With the fast development of supercomputers, new software packages need to be developed in order to fully make use of hardware and software progresses. In this paper, we will introduce a new BDS software package, LOCUS3D, which is developed for efficient use of these new techniques. It is based on Particle-In-Cell (PIC) method, and includes space charge effect by solving the Poisson’s equation. Parallel Poisson solver has been developed with MPI. Standard accelerator devices can be simulated and new devices can be added. Benchmark results have been obtained on several different platforms, such as INSPUR cluster at RDCPS, BG/P at ANL. Large-scale simulation with 109 particles can be simulated now in the simulations. LOCUS3D will be used for more realistic accelerator simulations in the near future.  
 
MOPWO014 Numerical Methods to the Space Charge Compensation (SCC) Effect of the LEBT Beam electron, ion, simulation, ion-source 915
 
  • S.X. Peng, J. Chen, J.E. Chen, Z.Y. Guo, P.N. Lu, Y.T. Luo, H.T. Ren, Z.H. Wang, Y. Xu, T. Zhang, J. Zhao
    PKU, Beijing, People's Republic of China
  • A.L. Zhang
    Graduate University, Chinese Academy of Sciences, Beijing, People's Republic of China
  
  Numerical simulation as well as experimental researches on space charge compensation for high intensity, low energy ion beam has been done at Peking University (PKU). In this paper we will describe the simulation model proposed at PKU and use it on the PKU ECR single-charged ion source. It consists of a new concept of equivalent density and more consideration of physical process. A series of arithmetical equations is gained through theoretical derivation. Although no numerical solutions have been carried out from our computation, it is foreseeable that the final result will be achieved soon.  
 
MOPWO020 Space Charge Dominated Envelope Dynamics using GPUs simulation, controls, luminosity, focusing 924
 
  • N.V. Kulabukhova
    St. Petersburg State University, St. Petersburg, Russia
  
  High power accelerator facilities lead to necessity to consider space charge forces. It is therefore important to study the space charge dynamics in the corresponding channels. To represent the space charge forces of the beam we have developed special software based on some analytical models for space charge distributions. Because calculations for space charge dynamics become extremely time consuming, we use a special algorithm for predictor-corrector method for evaluation scheme for beam map evaluation including the space charge forces. This method allows us to evaluate the map along the references trajectory and to create the beam envelope dynamics. The corresponding computer codes are realized using CUDA implementation of maps for particle dynamics. Some numerical results for different types of the beam channels are discussed. The survey of advantages and disadvantages of using different methods of parallelization and some parallel approaches will be done.  
 
MOPWO057 A Precise Beam Dynamics Model of the PSI Injector 2 cyclotron, simulation, injection, emittance 1020
 
  • A.M. Kolano, R.J. Barlow
    University of Huddersfield, Huddersfield, United Kingdom
  • A. Adelmann, C. Baumgarten
    PSI, Villigen PSI, Switzerland
  
  The Injector 2 at PSI (Paul Scherrer Institut), is a 72 MeV separate sector cyclotron producing a high intensity proton beam up to 3 mA CW, which is subsequently injected to the 590 MeV Ring Cyclotron. The injection energy of the pre-bunched beam is 870 keV at an intensity of 10 to 11 mA. In this paper we describe a full 3D model of the PSI injector 2, starting just before the two bunchers and including the multi stage collimation scheme in the cyclotron. The precise beam dynamics model is based on the OPAL (Object Oriented Parallel Accelerator Library) simulation code. OPAL is a tool for charged-particle optic calculations in large accelerator structures and beam lines including 3D space charge. The presented model will be validated with data from radial profile measurements and loss rates from the collimators and the electrostatic septum in the Injector 2. Based on this model we will estimate the intensity limit of this machine and comment of future operation modes.  
 
MOPWO070 Higher Order Symplectic Integration of Collective Effects collective-effects, simulation, wakefield, beam-transport 1046
 
  • S.D. Webb, D.T. Abell
    Tech-X, Boulder, Colorado, USA
  
  Long time tracking simulations of intense beams requires a proper account for the collective effects. Many tracking codes allow the number of space charge kicks, for example, to be determined by the end user. This makes no guarantee that the integration is second order accurate in the step size. In this proceeding, we present results on the proper second- and fourth-order symplectic integration of the Hamiltonian dynamics of particles under collective interactions using a model Hamiltonian with collective space charge forces to illustrate the underlying principles.  
 
MOPWO085 A Hybrid Technique for Computing Courant-Snyder Parameters from Beam Profile Data emittance, simulation, linac, DTL 1073
 
  • C.K. Allen
    ORNL, Oak Ridge, Tennessee, USA
  • E.N. Dai
    Washington University in St. Louis, St. Louis, USA
  
  Funding: Work supported by ORNL/SNS, which is managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725.
We present a technique for computing the Courant-Snyder parameters of a charged-particle beam from profile measurement data. Such algorithms are not new, but this particular method has very robust convergence properties resulting from a novel approach that combines both deterministic and non-deterministic methods. The general idea is as follows: given a model of the beamline, in the zero-current case it is possible to compute the Courant-Snyder parameters directly from profile data using a deterministic, linear-algebraic approach. For the finite beam current case we can construct a smooth curve of these deterministic solutions starting from the zero-current solution and terminating at the finite-current case. We are guaranteed convergence, and convergence to the finite-current solution connected to the zero-current Courant-Snyder parameters. This approach avoids the convergence issues associated with a fully iterative, non-deterministic method. The details of the technique are outlined and examples are presented using profile data taken from the SNS accelerator. 		 
 
TUPEA035 Plasma Effect in the Longitudinal Space Charge Induced Microbunching Instability plasma, impedance, electron, background 1220
 
  • D. Huang, Q. Gu
    SINAP, Shanghai, People's Republic of China
  • K.Y. Ng
    Fermilab, Batavia, USA
  
  Funding: National Science Foundation of China (NSFC), grant No. 11275253, and US DOE, contract DE-FG02-92ER40747.
In many cases, the longitudinal space charge (LSC) is a dominant factor to bring in the microbunching instability in the LINAC of a Free-Electron-Laser (FEL) facility. The current model of LSC impedance* derived from the fundamental electromagnetic theor** is widely used to explain the physics of the LSC-induced microbunching instability***. However, in the case of highly bright electron beams, the plasma effect starts to play a role. In this paper, the basic model of the LSC impedance including the plasma effect is built up by solving the Vlasov and Poisson equations in 6 dimensional phase space, and the investigation is done to study the modification to the gain of the instability based on the model. The solutions indicate that the gain does not only depend on the spatial information of the beam, but also on the velocity (momentum) and time information. The comparison of the gains of the microbunching instability in the LINAC of Shanghai soft X-ray Free Electron Laser Facility (SXFEL) computed by various methods is also given and the discrepancy is illustrated.
* Marco Venturini, Phys. Rev. ST Accel. Beams 11, 034401 (2008)
** J. D. Jackson, Classical Electrodynamics (Wiley, 1999)
*** Z. Huang, et. al., Phys, Rev. ST Accel. Beams 7, 074401 (2004)
 		 
 
TUPEA062 Advanced Gabor Lens Lattice for Medical Applications laser, ion, proton, focusing 1277
 
  • J.K. Pozimski, M. Aslaninejad, P.A. Posocco
    Imperial College of Science and Technology, Department of Physics, London, United Kingdom
  
  The widespread introduction of Hadron therapy for cancer treatment is inhibited by the large costs for the accelerator and treatment facility and the subsequent maintenance costs which reflects into the cost per treatment. In the long term future (laser) plasma wakefield accelerated hadrons could offer compact treatment devices with significantly reduced treatment costs. In the moment the particle distributions produced by such accelerators do not fulfill the medical requirements. Beside the reliable production of a sufficient number of ions at the required energy the formation of a particle beam suitable for treatment from the burst of ions created in the acceleration process is one of the major challenges. While conventional optical systems will be operating at the technical limits which would be contradictory to the cost argument, space charge lenses of the Gabor type might be a cost effective alternative. An advanced beam line consisting of Gabor lenses, a few cavities and an dipole will be presented together with results from particle transport simulations.  
 
TUPFI088 Space-charge Studies for Ionization Cooling Lattices emittance, lattice, collider, simulation 1553
 
  • D. Stratakis, R.B. Palmer
    BNL, Upton, Long Island, New York, USA
  • D.P. Grote
    LLNL, Livermore, California, USA
  
  Funding: This work is funded by US Dept. of Energy grant numbers DE AC02-98CH10886
Intense muon beams provide a promising solution to a variety of applications ranging from nanotechnology to nuclear detections systems and from medical sciences to high energy physics. Production of such intense beam requires the beam to be cooled and ionization cooling via particle matter interaction is considered one of the most practical methods. Here a theoretical and numerical study on space-charge effects on such ionization cooling channels is presented. We show that space-charge can strongly affect the design of muon cooling systems by limiting their minimum cooling rate. Space-charge compensation solutions are discussed and the minimum cooling emittance as a function of the beam charge and pulse width is identified. 		 
 
TUPME001 Effect of Self-consistency on Space Charge Induced Beam Loss resonance, simulation, emittance, controls 1556
 
  • G. Franchetti
    GSI, Darmstadt, Germany
  
  In long term storage space charge driven incoherent effect may lead to a slow beam diffusion that causes emittance growth and beam loss. However, when beam loss are relevant the full mechanism cannot be understood only driven by an incoherent effect. In this proceeding the issue of the self-consistency is discussed, and its impact presented for simplified examples and for the SIS100.  
 
TUPME012 Space Charge Simulation based on a Measured Optics in J-PARC MR optics, resonance, sextupole, coupling 1589
 
  • K. Ohmi, S. Igarashi, Y. Sato, J. Takano
    KEK, Ibaraki, Japan
  • S. Hatakeyama
    JAEA/J-PARC, Tokai-mura, Japan
  
  Linear optics parameters, beta, alpha, phase, x-y coupling and dispersion are measured by phase space monitor and/or other tools. Nonlinear effects due to the space charge and magnets are dominantly determined by linear optics. For example, the beam distribution is mainly determined by linear optics, and error of beta function at a sextuple magnet is larger than error of magnet strength generally. This means space charge simulation based on the measured optics takes into account of the major part of errors. We discuss how beam loss degrade and which resonances are induced by the errors in the simulations.  
 
TUPME034 Experimental Studies for Future LHC Beams in the SPS emittance, injection, optics, brightness 1652
 
  • H. Bartosik, T. Argyropoulos, T. Bohl, S. Cettour-Cave, J. Esteban Müller, W. Höfle, G. Iadarola, Y. Papaphilippou, G. Rumolo, B. Salvant, F. Schmidt, E.N. Shaposhnikova, H. Timko
    CERN, Geneva, Switzerland
  • A.Y. Molodozhentsev
    KEK, Ibaraki, Japan
  
  The High Luminosity LHC (HL-LHC) project requires significantly higher beam intensity than presently accessible in the LHC injector chain. The aim of the LHC injectors upgrade project (LIU) is to prepare the CERN accelerators for the future needs of the LHC. Therefore a series of machine studies with high brightness beams were performed, assessing the present performance reach and identifying remaining limitations. Of particular concern are beam loading and longitudinal instabilities at high energy, space charge for beams with 50ns bunch spacing and electron cloud effects for beams with 25ns bunch spacing. This paper provides a summary of the performed studies, that have been possible thanks to the implementation of the SPS low gamma-transition optics.  
 
TUPME046 Performance of SPS Low Transition Energy Optics for LHC Ion Beams optics, ion, emittance, scattering 1667
 
  • F. Antoniou, G. Arduini, H. Bartosik, T. Bohl, S. Cettour Cave, K. Cornelis, D. Manglunki, Y. Papaphilippou
    CERN, Geneva, Switzerland
  
  An optics with low transition energy has been developed in the SPS for removing intensity limitations of the LHC proton beam and has become operational towards the second part of the 2012 LHC proton run. This optics was also used for filling the LHC with lead ions during the p/Pb run of the beginning of 2013. The impact of this optics in the performance of the LHC ion beam is studied here, especially with respect to collective effects, at the SPS injection energy. In particular, the potential gain of the increased beam sizes provided by this optics, with respect to losses and emittance blow up due to space-charge and Intrabeam Scattering (IBS) is evaluated. The measured lifetime is compared with the one provided by the Touschek effect and its interplay with RF noise is studied. The models are supported by measurements in the SPS and in the LHC flat bottom.  
 
TUPME047 Sub-Harmonic Bunching System of CLIC Drive Beam Injector bunching, collider, klystron, acceleration 1670
 
  • S. Sanaye Hajari, S. Döbert, S. Döbert, H. Shaker
    CERN, Geneva, Switzerland
  • S. Sanaye Hajari, H. Shaker
    IPM, Tehran, Iran
  
  In the Compact Linear Collider (CLIC) the RF power for the acceleration of the Main Beam is extracted from a high-current Drive Beam that runs parallel with the main linac. The sub-harmonic bunching system of the drive beam injector has been studied in detail and optimized. The model consists of a thermionic gun, three travelling wave sub-harmonic bunchers followed by a tapered travelling wave buncher. The simulation of the beam dynamics has been carried out with PARMELA with the goal of optimizing the overall bunching process and in particular capturing particles as much as possible in the buncher acceptance and decreasing the satellite population.  
 
TUPME064 Envelope Perturbations in a Space-Charge-Dominated Electron Beam simulation, resonance, quadrupole, lattice 1712
 
  • W.D. Stem, B.L. Beaudoin, I. Haber, R.A. Kishek, T.W. Koeth
    UMD, College Park, Maryland, USA
  
  Funding: Supported by the US Dept. of Energy, Office of High Energy Physics, and by the US Dept. of Defense, Office of Naval Research and the Joint Technology Office.
Linear perturbation analysis of the RMS envelope equations predicts a frequency splitting of the transverse envelope resonances with the onset of space charge. These resonances are a potential source of beam degradation for space-charge-dominated particle accelerators and storage rings. We use WARP for both envelope code integration and particle-in-cell (PIC) simulations to predict the behavior of these resonances for an existing alternating gradient lattice storage ring. The focus of these simulations is tailored toward examining physics that is scalable to future high-intensity accelerators. This paper provides detailed simulation results and a design for an experimental demonstration at the University of Maryland Electron Ring (UMER), a high intensity 10 keV electron storage ring. 		 
 
TUPWA004 Advanced Considerations for Designing Very High-intensity Linacs through Novel Methods of Beam Analysis, Optimization, Measurement & Characterisation emittance, linac, extraction, rfq 1727
 
  • P.A.P. Nghiem, N. Chauvin, D. Uriot
    CEA/DSM/IRFU, France
  • W. Simeoni
    CEA/IRFU, Gif-sur-Yvette, France
  
  Research in fundamental physics, nuclear physics or advanced materials, requires linear accelerators as irradiation sources with higher and higher beam intensity. In such machines, not only high beam power but also high space charge are the major challenges. This double concern often induces conflicting issues, which should be overcome from the accelerator design stage. It progressively appears that the usual methods are no more sufficient. Even new concepts are to be invented. With mega-watt beams, losses and also micro-losses must be minimised while with very strong space charge, few room can be reserved for beam diagnostics. New strategies for design and tuning are to be carried out. The beam itself can no more be described only by its classical values like emittance and Twiss parameters. Core and halo parts should be instead precisely defined and kept under surveillance. The beam phase space distribution itself becomes determinant, which is very far from waterbag or gaussian distributions. This paper aims at proposing new considerations for very high-intensity linacs while recalling the usual ones, from designing and tuning methods to beam definitions and characterisations.  
 
TUPWA019 Comparison of Tracking Simulation with Experiment on the GSI UNILAC DTL, emittance, simulation, linac 1763
 
  • X. Yin
    IHEP, Beijing, People's Republic of China
  • W.A. Barth, W.B. Bayer, L. Groening, I. Hofmann, S.G. Richter, S.G. Yaramyshev
    GSI, Darmstadt, Germany
  • A. Franchi
    CERN, Geneva, Switzerland
  • A.C. Sauer
    IAP, Frankfurt am Main, Germany
  
  In the European framework “High Intensity Pulsed Proton Injector” (HIPPI), the 3D linac code comparison and benchmarking program with experiment have been initialed. PARMILA and HALODYN are involved in this work. Both of these codes have been developed and used for linac design and beam dynamics studies. In this paper, we compare the simulation results with experiment results which was carried out on the UNILAC Alvarez DTL. And discuss physics aspects of the different linac design and beam dynamics simulation codes.  
 
TUPWA020 The Implementation of Equipartitioning in the Proton Linac Code PADSC emittance, lattice, quadrupole, linac 1766
 
  • Y.L. Zhao, S. Fu, Z. Li
    IHEP, Beijing, People's Republic of China
  
  The high intensity accelerator projects place extremely stringent requirements on particle loss, since even very small losses can lead to unacceptably high levels of radioactivity that can hinder or prevent hands-on maintenance. Such losses are known to be associated with emittance growth and beam halo. Non-equipartitioning contributes a lot for emittance growth and beam halo. The present equipartitioning realization has assumed that the emittance and space charge force are keeping constant, which will induce errors. The implementation in the proton linac code PADSC does equipartitioning optimization according to the real space charge force and emittance in the quasi period lattice.  
 
TUPWA025 DESIGN STUDIES OF THE C-ADS MAIN LINAC WITH ONLY SPOKE CAVITIES linac, emittance, proton, simulation 1781
 
  • S.H. Liu, Y. He, Z.J. Wang
    IMP, Lanzhou, People's Republic of China
  
  The China ADS(C-ADS) project undertaken by the Chinese Academy of Science is based on superconducting proton linac. The design goal is to accelerate 10mA CW proton beam up to 1.5GeV. The accelerator includes an injector section and a main superconducting linac. Two injectors are under studying by IHEP and IMP respectively. In this paper, an alternative design of the main linac with full spoke cavity base on the beam characteristics from IMP injectorⅡis described. In addition, multi-particle beam dynamics simulations have been performed using TraceWin code to estimate the space charge effect.  
 
TUPWA034 On the Choice of Linac Parameters for Minimal Beam Losses linac, emittance, resonance, beam-losses 1787
 
  • M. Eshraqi
    ESS, Lund, Sweden
  • J.-M. Lagniel
    GANIL, Caen, France
  
  In high intensity linear accelerators, the tune spreads induced by the space-charge forces in the radial and longitudinal planes are key parameters for halo formation and beam losses. For matched beams they are the parameters governing the number of resonances (including coupling resonances) which affect the beam and determine the respective sizes of the stable and halo areas in phase space. The number and strength of the resonances excited in mismatched beams leading to even higher amplitude halos are also directly linked to the tune spreads. In this paper, the equations making the link between the basic linac parameters (rf frequency, zero-current phase advances, beam intensity and emittances) and the tune spreads are given. A first analysis of the way these linac parameters can be chosen to minimize the tune spreads is presented. The parameters of ESS linac are used for this study.  
 
TUPWA045 Longitudinal Space Charge Effects in the CLIC Drive Beam simulation, quadrupole, lattice, luminosity 1811
 
  • R.L. Lillestøl, S. Döbert, A. Latina, D. Schulte
    CERN, Geneva, Switzerland
  • E. Adli, K.N. Sjobak
    University of Oslo, Oslo, Norway
  
  The CLIC main beam is accelerated by rf power generated from a high-intensity, low-energy electron drive beam. The accelerating fields are produced in Power Extraction and Transfer Structures, and are strongly dependent on the drive beam bunch distribution, as well as other parameters. We investigate how longitudinal space charge affects the bunch distribution and the corresponding power production, and discuss how the bunch length evolution can affect the main beam. We also describe the development of a Particle-in-Cell space charge solver which was used for the study.  
 
TUPWA058 Experimental Study of Soliton Wave Trains in Intense Electron Beams electron, simulation, laser, induction 1835
 
  • Y. Mo, B.L. Beaudoin, D.W. Feldman, I. Haber, R.A. Kishek, P.G. O'Shea
    UMD, College Park, Maryland, USA
  
  Funding: Supported by the US Dept. of Energy, Office of High Energy Physics, and by the US Dept. of Defense, Office of Naval Research and the Joint Technology Office.
Longitudinal perturbations in intense beams can lead to instabilities or degradation of beam quality, ultimately affecting the performance of accelerators, especially near the source where space charge is important. In this experimental study, conducted on the University of Maryland Electron Ring (UMER), large-amplitude perturbations are purposefully generated and their propagation observed over a long transport length. It is found that narrow, large-amplitude perturbations on a long-pulse beam develop into Korteweg-deVries (KdV) type soliton wave trains. Each peak in the wave train has a constant width and amplitude over a long propagation distance, with the amplitude inversely proportional to the square of the width. Furthermore, two such pulses are seen to interact with each other and emerge from the collision unchanged. The experimental data is compared with the KdV model and particle-in-cell simulations with good agreement. We induce perturbations using two methods: using photoemission to perturb the density at the cathode, or using an induction cell to directly perturb particle velocities. 		 
 
TUPWA064 Suppression of Halo Formation in FODO Focusing Channel with Nonlinear Focusing quadrupole, multipole, focusing, emittance 1850
 
  • Y.K. Batygin, A. Scheinker
    LANL, Los Alamos, New Mexico, USA
  
  Averaging method was applied to analyze focusing properties of a quadrupole FODO channel with inserted multipole lenses. General expression for averaged focusing potential is obtained as a function of position of multipole lenses with respect to FODO quadrupole lenses. Obtained results were applied to the problem of intense beam transport in combined FODO structure. Numerical and analytical treatments of high-brightness beam dynamics with suppressed space-charge induced halo formation are presented.  
 
TUPWA065 Design Issues of Low Energy Beam Transport solenoid, focusing, emittance, ion 1853
 
  • Y.K. Batygin
    LANL, Los Alamos, New Mexico, USA
  
  Low energy beam transport (LEBT) is an important element of ion accelerator facilities to provide beam matching between ion source and accelerator structure, perform required beam diagnostics measurements, dispose extra particle components, and create necessary time structure of the beam. Most of existing ion LEBT are based on solenoid focusing. Design criteria for ion LEBT with magnetostatic focusing are discussed. Dynamics in LEBT is optimized in terms of maximizing acceptance of the channel and transported beam current, and minimizing spherical aberrations in solenoids and space charge induced beam emittance growth.  
 
TUPWA066 Space Charge Neutralization of Low Energy H− Beam emittance, simulation, ion, ion-source 1856
 
  • Y.K. Batygin, I.N. Draganić, C.M. Fortgang, G. Rouleau
    LANL, Los Alamos, New Mexico, USA
  
  LANSCE Ion Source Test Stand is used for systematic study of H− source performance and details of low energy beam transport. It includes cesiated, multicusp-field, surface –production H− ion source, focusing solenoids, slit-collector emittance stations, 4.5o bending magnet, and electrostatic deflector. Series of experiments were performed to measure space charge neutralization of low energy H− beam. Measurements were done for 80 keV and 35 keV H− beams at various pressure of residual gas. Results of measurements are compared with results of beam dynamics simulations to determine level of space charge neutralization. Applicability of theoretical models of beam neutralization is discussed.  
 
TUPWA067 Beam Emittance Growth Effects in High-intensity RFQ resonance, rfq, emittance, linac 1859
 
  • Y.K. Batygin, R.W. Garnett, L. Rybarcyk
    LANL, Los Alamos, New Mexico, USA
  
  Beam dynamics in an RFQ are strongly affected by coupling between transverse and longitudinal particle oscillations. The adiabatic process of high-intensity bunched beam formation results in equipartitioning in the RFQ, which determines the longitudinal beam emittance. Avoiding parametric resonances is an important design criterion to prevent significant emittance growth of the beam. Manufacturing errors can result in beam emittance growth and reduction of beam transmission. This paper will present the results of a study where analytical and numerical evaluations were performed to determine the effect of the aforementioned factors on beam quality in a high-current RFQ.  
 
TUPWO008 High-Current Beam Transport Simulations Including Gabor Lenses in Varying Non-Neutral Plasma States electron, simulation, focusing, plasma 1892
 
  • M. Droba, H. Dinter, O. Meusel, D. Noll, U. Ratzinger, K. Schulte
    IAP, Frankfurt am Main, Germany
  
  The Gabor space charge lens has theoretically and experimentally been investigated at IAP for many years. Especially the application in high current, Low Energy Beam Transport (LEBT) sections seems efficient and attractive. The focusing properties and imaging quality of this lens type depend on the transverse and longitudinal confinement of the electron column. Different non-neutral plasma states have been observed and calculated. In general, they can be disturbed by the interaction with ion beams. This results in a shift and in a modification of the work function with a rise of aberrations and beam emittance growth. It is necessary to understand such processes for transport channels using intense ion beams to preserve the high beam brilliance. The beam transport simulations including Gabor lenses in various non-neutral plasma states will be presented and compared with experimental results.  
 
TUPWO022 Space Charge Effects Study and Optimization in CSNS/LRBT emittance, lattice, linac, injection 1928
 
  • Z.P. Li, N. Huang, W.B. Liu, S. Wang
    IHEP, Beijing, People's Republic of China
  
  The linac to ring beam transport line (LRBT) of China Spallation Neutron Source (CSNS) connecting the linac and the rapid cycling synchrotron (RCS) transports 80 MeV negative hydrogen ions (H−) beams for RCS injection. Space charge effect in LRBT is significant due to small emittance and high current density of the beam, which is a major cause of emittance growth and beam loss. An achromatic transverse optical matching was performed by TRACE 3D code. Emittance growths of beams with different initial distributions in different LRBT lattices were studied separately. Simulation results show that the LRBT design with triplet can mitigate the emittance growth by lattice optimization of the front matching section and no beam loss occurs at 15mA. The location and parameters of the debuncher in LRBT were also optimized to reduce the momentum spread and energy jitter.  
 
TUPWO034 Focusing Magnetic Field Design for a FEL Linac linac, focusing, electron, solenoid 1949
 
  • Q.S. Chen, Q. Fu, T. Hu, B. Qin, B. Wu, H. Zeng
    HUST, Wuhan, People's Republic of China
  • J. Li, Y.J. Pei
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  
  A linac-based Free Electron Laser is planned to be built in Huazhong University of Science and Technology (HUST). As an important part of the whole project, the focusing magnetic field is carefully designed. Space-charge force is calculated at first to give a rough evaluation about the focusing field. Start-to-end simulation shows that the magnetic field has only great effect on spot size and phase space. With the final designed field, 10-ps-length pulse containing 200pC electrons can be got and the corresponding RMS emittance and RMS radius are 7 πmm•mrad and 0.25 mm, respectively. Finally, a new idea (double-peak scheme) is discussed and excitation current is proposed as the evaluation index.  
 
TUPWO046 The ESS Linac Simulator: A First Benchmark with TraceWin linac, simulation, cavity, multipole 1970
 
  • E. Laface, M. Eshraqi, R. Miyamoto
    ESS, Lund, Sweden
  
  The ESS Linac Simulator, ELS, will be the core of the online model used in the normal operations of the ESS linac. ESS Linac Simulator will operate through the eXtensible Accelerator Language, XAL, in order to provide an effective interface capable to simulate and predict the beam dynamics of the accelerator. The ELS is capable of simulating the dynamics of the beam envelope in both transverse and longitudinal planes in real time. In order to validate the effectiveness of the physics implemented, the ELS calculations are here benchmarked with TraceWin: the simulation code used for the design of the accelerator.  
 
TUPWO056 Modelling of the EMMA ns-FFAG Ring using GPT simulation, electron, injection, closed-orbit 1994
 
  • R.T.P. D'Arcy
    UCL, London, United Kingdom
  • J.K. Jones, B.D. Muratori
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • S.B. van der Geer
    Pulsar Physics, Eindhoven, The Netherlands
  
  EMMA (Electron Machine with Many Applications) is a prototype non-scaling Fixed-Field Alternating Gradient (ns-FFAG) accelerator whose construction at Daresbury Laboratory, UK, was completed in the autumn of 2010. The energy recovery linac ALICE serves as an injector for the EMMA ring, within an effective energy range of 10 to 20 MeV. The ring is composed of 42 cells, each containing one focusing and one defocusing quadrupole. Acceleration over many turns of the EMMA machine has recently been confirmed. In some cases the bunch will traverse upwards of 100 turns, at which point the effects of space-charge may be significant. It is therefore necessary to model the electron beam transport in the ring using a code capable of both calculating the effect of and compensating for space-charge. Therefore the General Particle Tracer (GPT) code has been used. A range of injection beam parameters have been modelled for comparison with experimental results and those of other codes. The simulated effects of space-charge on the tune shift of the machine are also compared with those expected from theory.  
 
WEOAB103 Experimental Observations of a Multi-stream Instability in a Long Intense Beam simulation, electron, factory, background 2044
 
  • B.L. Beaudoin, S. Bernal, I. Haber, R.A. Kishek, T.W. Koeth
    UMD, College Park, Maryland, USA
  
  Funding: Supported by the US Dept. of Energy, Office of High Energy Physics, and by the US Dept. of Defense, Office of Naval Research and the Joint Technology Office.
We have observed evidence of a multi-stream instability in a long non-relativistic space-charge dominated beam evolving with an initial non-linear distribution and zero external longitudinal containment. This type of instability can be detrimental to intense accelerators that propagate rectangular distributions, such as in a ring with single or multi-bunch injection. The longitudinal forces in these intense bunches causes the beam to expand axially; in the case of the University of Maryland Electron Ring (UMER), the initial long bunch is injected to fill a fraction of the ring, coasting beyond the point where the head and tail overlap. Adjacent filaments at that point are separated in velocity space by 2cs and approach a separation of cs. The onset of the instability has been observed to depend on the injected beam current, bunch length, and other experimental factors. Comparisons with simple analytical calculations and PIC simulations have shown good agreement in the time to onset. 		 
slides icon Slides WEOAB103 [1.681 MB]  
 
WEPWA008 Simulating the Bunch Structure in the THz Source FLUTE simulation, laser, linac, dipole 2141
 
  • S. Naknaimueang, E. Huttel, S. Marsching, A.-S. Müller, M.J. Nasse, R. Rossmanith, M. Schreck, M. Schuh, M. Schwarz, M. Weber, P. Wesolowski
    KIT, Karlsruhe, Germany
  • M.T. Schmelling
    MPI-K, Heidelberg, Germany
  
  FLUTE is a planned THz source at KIT operating at a beam energy of 40 to 50 MeV in a wide bunch charge range. It consists of a laser driven rf-gun, a linac and a magnetic bunch compressor. The high current density combined with relatively low energy of FLUTE leads to complex strong self-field and beam-radiation field interactions, which are the limiting factors for the bunch compression efficiency. The results of numerical studies are presented in this paper.  
 
WEPWA009 RF Bunch Compression Studies for FLUTE linac, cavity, simulation, gun 2144
 
  • M. Schuh, E. Huttel, S. Marsching, A.-S. Müller, S. Naknaimueang, M.J. Nasse, R. Rossmanith, R. Ruprecht, M. Schreck, M. Schwarz, M. Weber, P. Wesolowski
    KIT, Karlsruhe, Germany
  • R.W. Aßmann, K. Flöttmann, H. Schlarb
    DESY, Hamburg, Germany
  
  FLUTE is a planned 40 to 50 MeV accelerator test facility consisting, in the first phase, of an electron gun with an output energy of about 7 MeV, a traveling wave linac and a magnet chicane bunch compressor. The machine will serve as a source of intense THz radiation using coherent synchrotron radiation (CSR), coherent transition radiation (CTR), and coherent edge radiation (CER) as generation mechanisms. It is planned to operate the machine in the charge regime from a few pC up to several nC in order to study bunch compression schemes as well as the THz radiation generation. In this contribution the effect of velocity bunching by using a dedicated buncher cavity at low energy and operating the linac off-crest is studied in order to deliver RMS bunch lengths in the femtosecond range at low charge.  
 
WEPWA064 Simulations of the ALICE ERL FEL, linac, simulation, electron 2265
 
  • J.K. Jones, D.J. Dunning, F. Jackson, J.W. McKenzie, P.H. Williams
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  
  ALICE is a low-energy Energy Recovery Linac operated at Daresbury Laboratory in Cheshire, UK. The ALICE injector is based around a 350 kV DC photo-cathode electron gun. With an operating voltage of 325 keV, electron dynamics in the ALICE injector are space-charge dominated and highly non-linear, and this complicates simulations of the beam dynamics in this region. With an intermediate energy of 6.5 MeV, and a final ring energy of 27.5 MeV, the space-charge effects in the rest of the machine can also not be ignored. In this paper we summarise some of the work that has been performed to understand and optimise the simulations of the ALICE ERL, in several different operating modes, and using several different modelling codes.  
 
WEPWA091 Simulation Design of a Low Energy Bunch Compressor with Space Charge Effect gun, electron, dipole, cathode 2307
 
  • A. He, Y. Hidaka, T.V. Shaftan, G.M. Wang, F.J. Willeke, L. Yang, L.-H. Yu
    BNL, Upton, Long Island, New York, USA
  
  Funding: Department of Energy, USA
Following the proposal of electron beam slicing method to generate short x-ray pulses in storage ring, we studied the feasibility of the crucial technique required by electron beam slicing, i.e., the generation of very low energy electron beam with very small beam size (30 μm) and very short bunch length (100 fs). Based on one of the BNL RF gun, 5 MeV beam energy and 50 pC bunch charge was assumed in the study. The beam ‘natural’ energy-time negative chirp, due to space charge effect, was used and the bunch length is compressed from from 0.8 ps to ~150 fs with a chicane structure. The system is in the space charge dominated regime. We use the code PARMELA and Generic optimization method for parameters optimization with various strategies to overcome the damaging from the space charge effect. After optimization, the beam transverse size is 50 micron and the bunch length is 150 fs, close to our original specification. In this paper we describe the design and the physical process in the compressor and focus section. The study confirmed the possibility to generate strong focused and compressed very low energy beam in the space charge dominated regime. 		 
 
WEPEA015 Possibility Study of High Repetition Rate Operation of JPARC Main Ring sextupole, injection, multipole, quadrupole 2528
 
  • K. Fan, S. Igarashi, K. Ishii, T. Koseki, M. Uota
    KEK, Ibaraki, Japan
  
  The original design of JPARC main ring is to provide high beam power of 750 kW with machine repetition rate of 0.3 Hz. However, the severe space charge effects at low injection energy limit the beam intensity. In order to raise the beam power to the design limit, one logical way is to increase the repetition rate. However, the resulting eddy current in the laminations and pipes may impair the field quality of all magnets. In addition, the activation of beam pipe becomes severer in high beam power operation. Titanium beam pipe is proposed to replace the stainless steel pipe to reduce the activation and decrease the decay time. However, titanium has lower resistivity, severer eddy current effects are expected. The studies investigate the eddy current effects on field quality of the main dipole, quadrupole and sextupole magnets.  
 
WEPEA023 Space Charge Effects for Different CSNS/RCS Working Points resonance, lattice, simulation, emittance 2549
 
  • S.Y. Xu, N. Wang, S. Wang
    IHEP, Beijing, People's Republic of China
  
  The China Spallation Neutron Source (CSNS) operates at 25 Hz repetition rate with the design beam power of 100 KW. CSNS consists of an 80-MeV linac and a 1.6-GeV Rapid Cycling Synchrotron (RCS). Due to the high beam density and high repetition rate for CSNS/RCS, the rate of beam loss must be controlled to a very low level. The major source of beam loss is associated with resonances. Thus, choosing he best suitable working points on the tune diagram is important to reach low beam loss. Different tune areas are explored and compared by considering resonances and the effects of space charge, which can drive particles into the excited resonances. Different working points are simulated and compared by using the codes ORBIT and SIMPSONS.  
 
WEPEA024 Combine Effects of Space Charge and Chromaticity Sextupoles at CSNS/RCS sextupole, emittance, simulation, acceleration 2552
 
  • S.Y. Xu, S. Wang
    IHEP, Beijing, People's Republic of China
  
  Most high current proton synchrotrons, such as The Rapid Cycling Synchrotron (RCS) of The China Spallation Neutron Source (CSNS), are operated under the transition energy, and the natural chromaticity is small. These proton synchrotrons can work without chromatic correction. To reduce the tune spread produced by the chromaticity, chromatic correction is considered by using chromaticity sextupoles for this type of proton synchrotrons, such as J-PARC and SNS. Many chromatic correction schemes are compared for the CSNS/RCS, and the harmonic sextupoles are considered to correct nonlinear effect of chromaticity sextupoles. The dynamic aperture is obtained by particle tracking, and the combine effects of sextupole field and space charge effects are investigated by using the code ORBIT and SIMPSONS.  
 
WEPEA033 Optimization of Injector System for Early Commissioning Phase of Compact-ERL. emittance, laser, solenoid, gun 2573
 
  • J.G. Hwang, E.-S. Kim
    Kyungpook National University, Daegu, Republic of Korea
  • T. Miyajima
    KEK, Ibaraki, Japan
  
  Injector system of Compact-Energy Recovery Linear accelerator, which is currently develping in Photon Factory of KEK at Japan, consists of the photo-cathode DC gun, two solenoids, a 1.3 GHz buncher ,three 1.3 GHz 2 cell injector cavities, 5 quadrupole magnet and merger section. Target values of beam produced by the injector system are kinetic energy of 5 MeV, the normalized transverse emittance of under 0.1 mm-mrad and the bunch length of under 3 ps with the 7.7 pC charge per bunch and the repetition rate of 1.3 Ghz. In this low energy region, the effect of the space charge is dominated to cause the emittance growth. The optimization is performed by using MOGA (Multi-Object Genetic Algorithm) with code GPT to consider the effect of space charge under optimization. The code General Particle Tracer (GPT) is a 3D Paricle-In-Cell(PIC) code based on multi-layer object-oriented design. Using this method with code GPT, the target values was achieved at the exit of the merger section such as the normalized emittance of 0.1 mm-mrad with bunch length of 3 ps and kinetic energy of 5 MeV.  
 
WEPEA038 Two and three Dimensional Models for Analytical and Numerical Space Charge Simulation controls, linac, simulation, ion 2585
 
  • S.N. Andrianov, N.V. Kulabukhova
    St. Petersburg State University, St. Petersburg, Russia
  
  In this article there is described an analytical approach to describe the self-field of two- and three dimensional ellipsoidal presentation of space charge distribution. The corresponding results can be evaluated in both numerical and the analytic presentation for some model distributions of charge. The corresponding results can be embedded in the Lie formalism used to describe the map for the beam dynamics. The corresponding linear and nonlinear maps are evaluated in terms of the matrix representation of the evolution operator of the beam. Appropriate solutions for nonlinear differential equations are based on a prediction-correction method (the converging recursive procedure). These solutions are compared with the Vlasov equation solutions. A special software package for the described approach is presented.  
 
WEPEA040 Space Charge and Cavity Modeling for the ESS Linac Simulator linac, cavity, proton, simulation 2588
 
  • E. Laface, M. Eshraqi, R. Miyamoto
    ESS, Lund, Sweden
  
  The proton linac of the European Spallation Source will operate at unprecedented beam power of 5 MW. Such power requires a precise modeling of the beam dynamics in order to protect its components from losses. The high peak current of 62.5 mA produces a space charge force that dominates the dynamics at low energy, while the high gradient required to accelerate up to 2 GeV in the 500 m of linac length is challenging for the dynamics in the RF cavities. This paper presents modelings of the space charge force and RF cavities used in the ESS Linac Simulator. The simulator is under development as part of the XAL on-line model, and it will be adopted for the ESS linac operations.  
 
WEPEA052 Investigations on CERN PSB Beam Dynamics with Strong Direct Space Charge Effects Using the PTC-ORBIT Code simulation, emittance, resonance, injection 2621
 
  • V. Forte, E. Benedetto, C. Carli, M. Martini, B. Mikulec, E. Métral, F. Schmidt
    CERN, Geneva, Switzerland
  • A.Y. Molodozhentsev
    KEK, Ibaraki, Japan
  
  The CERN PS Booster (PSB) is the first synchrotron of the LHC injector chain consisting out of four superposed rings and providing beam for many users. As part of the LIU project, the machine will be upgraded. Space charge and resonances are serious issues for the good quality of the beam at injection energy. Consequently simulations are needed to track the beam in the machine taking into account space charge effects: PTC-ORBIT has been used as tracking code. This paper presents simulations results compared with the measurements for machine performances evaluation and code-benchmarking purposes.  
 
WEPEA070 Space Charge Effects and Limitations in the Cern Proton Synchrotron resonance, emittance, proton, injection 2669
 
  • R. Wasef, G. Arduini, H. Damerau, S.S. Gilardoni, S. Hancock, C. Hernalsteens, A. Huschauer, F. Schmidt
    CERN, Geneva, Switzerland
  • G. Franchetti
    GSI, Darmstadt, Germany
  
  Space charge produces a large incoherent tune-spread which, in presence of betatronic resonances, could lead to beam losses and emittance growth. In the CERN Proton Synchrotron, at the current injection kinetic energy (1.4 GeV) and even at the future kinetic energy (2 GeV), space charge is one of the main limitations for high brightness beams and especially for the future High-Luminosity LHC beams. Several detailed studies and measurements have been carried out to improve the understanding of space charge limitations to determine the maximum acceptable tune spread and identify the most important resonances causing losses and emittance growth.  
 
WEPEA073 A 180 MeV Injection Upgrade Design for the ISIS Synchrotron injection, synchrotron, simulation, acceleration 2678
 
  • J.W.G. Thomason, D.J. Adams, B.S. Drumm, D.J.S. Findlay, I.S.K. Gardner, M.C. Hughes, S.J.S. Jago, B. Jones, R.J. Mathieson, S.J. Payne, B.G. Pine, A. Seville, H. V. Smith, C.M. Warsop, R.E. Williamson
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
  • J. Pasternak
    STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
  • D.C. Plostinar, C.R. Prior, G.H. Rees
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
  
  ISIS is the spallation neutron source at the Rutherford Appleton Laboratory in the UK. Obsolescence and reliability issues are motivating plans to replace the present 70 MeV H minus linac, and this paper presents an overview of a design to allow injection of beam into the present ISIS ring at 180 MeV, which would increase intensity as a result of reduced space charge and optimised injection. The key topics addressed are design of the injection straight, injection painting and dynamics, foil specifications, acceleration dynamics, transverse space charge, instabilities, RF beam loading and activation.  
 
THOAB103 Phase Space Tomography Research at Daresbury quadrupole, electron, simulation, FEL 3096
 
  • K.M. Hock, D.J. Holder, M.G. Ibison, B.D. Muratori, A. Wolski
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  
  We report on the progress of phase space tomography research at Daresbury. The efforts over the past three years have been focussed on measuring the electron beam at the ALICE tomography section. Based on this result, we have developed techniques for improving resolution using normalised phase space, removing streaking artefacts by thresholding, demonstrating reliability of reconstructed phase space. We have developed in-house reconstruction codes using both the Filtered Back Projection and the Maximum Entropy Techniques. We are currently using a combination of simulation and measurements to investigate the onset of space charge effects at low bunch charges over short distances.  
slides icon Slides THOAB103 [0.878 MB]  
 
THYB101 Suppressing Transverse Beam Halo with Nonlinear Magnetic Fields lattice, resonance, damping, octupole 3099
 
  • S.D. Webb, D.T. Abell, D.L. Bruhwiler, J.R. Cary
    Tech-X, Boulder, Colorado, USA
  • V.V. Danilov
    ORNL, Oak Ridge, Tennessee, USA
  • S. Nagaitsev, A. Valishev
    Fermilab, Batavia, USA
  
  Funding: This work was supported in part by the US Department of Energy's Office of Science, Office of High Energy Physics, under grant No. DE-SC0006247.
Traditional space charge driven resonances, such as beam halo, arise due to the underlying linear nature of accelerator lattices. In this talk, we present initial results on a new class of intrinsically nonlinear lattices, which introduce a large tune spread naturally. The resulting nonlinear decoherence suppresses the onset of beam halo. 		 
slides icon Slides THYB101 [63.510 MB]  
 
THPME041 Configurable Field Magnets for a Proton Beam Dynamics R&D Ring multipole, dipole, injection, proton 3603
 
  • S.J. Brooks
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
  
  Magnets with many independently-powered coils can provide nearly arbitrary combinations of multipoles up to a certain order. This paper gives examples of field quality in such an "omni-magnet", which is normal-conducting and simulated with Poisson. Since the magnets also have quite large apertures they may be used to make a general-purpose FFAG and synchrotron test ring for beam dynamics studies. This could use the 3MeV H− beam from the RAL proton Front End Test Stand (FETS) and outline ring parameters are given for that situation.  
 
THPWA041 Acceptance and Transmission Simulations of the FETS RFQ emittance, rfq, simulation, solenoid 3720
 
  • S. Jolly, R.T.P. D'Arcy
    UCL, London, United Kingdom
  • A.P. Letchford
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
  • J.K. Pozimski
    Imperial College of Science and Technology, Department of Physics, London, United Kingdom
  • J.K. Pozimski
    STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
  
  A 4m-long, 324MHz four-vane RFQ, consisting of four coupled sections, has been designed for the Front End Test Stand (FETS) at RAL in the UK. A novel design method, integrating the CAD and electromagnetic design of the RFQ with beam dynamics simulations, was used to optimise the design of the RFQ. With the design of the RFQ fixed, the focus has been on optimising the transmission of the RFQ at 3 MeV and matching the output of the FETS Low Energy Beam Transport (LEBT) to the RFQ acceptance. Extensive simulations have been carried out using General Particle Tracer (GPT) to map out the acceptance of the FETS RFQ for a 65 keV H− input beam. Particular attention has focussed on optimising the simulations to match the optimised output of the FETS Penning-type H− ion source. Results are presented of the transverse phase space limits on the RFQ input acceptance in both the zero current and full space charge regimes.  
 
THPWA042 Investigation of Space Charge Compensation at FETS ion, ion-source, emittance, rfq 3723
 
  • J.K. Pozimski, S.M.H. Alsari, P. Savage
    Imperial College of Science and Technology, Department of Physics, London, United Kingdom
  • D.C. Faircloth, A.P. Letchford
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
  
  In order to contribute to the development of high power proton accelerators in the MW range, to prepare the way for an ISIS upgrade and to contribute to the UK design effort on neutrino factories, a front end test stand (FETS) is being constructed at the Rutherford Appleton Laboratory (RAL) in the UK. The aim of the FETS is to demonstrate the production of a 60 mA, 2 ms, 50 pps chopped beam at 3 MeV with sufficient beam quality. The ion source and LEBT are operational with the RFQ under manufacture. As a more detailed knowledge is of interest also for other projects like ESS and LINAC4 the FETS LEBT was updated to perform a detailed experimental analysis of space charge compensation utilizing a pulsed decompensation electrode together with a residual gas ion energy spectrometer and a fast emittance measurement device. In the FETS LEBT a high degree of space charge compensation (~90%) and a rise time of space charge compensation around ~ 50 μs could be concluded from measurements . In this paper the results of the experimental work will be presented together with discussion of the findings in respect to beam transport.  
 
THPWO005 Commissioning of the Spiral2 Deuteron Injector rfq, proton, emittance, solenoid 3764
 
  • D. Uriot, O. Tuske
    CEA/DSM/IRFU, France
  • J.-L. Biarrotte
    IPN, Orsay, France
  
  The SPIRAL-2 superconducting linac driver, which aims at delivering 5 mA, 40 MeV deuterons and up to 1 mA, 14.5 A.MeV q/A=1/3 heavy ions, has now entered its construction phase in GANIL (Caen, France). The linac is composed of two injectors feeding one single RFQ, followed by a superconducting section based on 88 MHz independently-phased quarter-wave cavities with room temperature focusing elements. The protons/deuteron injector have been fully built and commissioned at CEA Saclay in 2012, before moving and final installation at GANIL in 2013. Beam emittances have been measured at different positions of the LEBT and especially at the RFQ injection point. The space-charge beam compensation has been also carefully studied. This paper describes all the results obtained during this commissioning.  
 
THPWO021 Gabor Lens Performance Studies at the GSI High Current Test Injector emittance, ion, electron, beam-transport 3806
 
  • K. Schulte, M. Droba, O. Meusel, U. Ratzinger
    IAP, Frankfurt am Main, Germany
  • A. Adonin, R. Berezov, R. Hollinger, J. Pfister
    GSI, Darmstadt, Germany
  
  At the Institute for Applied Physics (IAP) the application of Gabor space charge lenses as a focusing device for low energy ion beams has already been studied for several years. Inside Gabor lenses electrons are confined by external fields. In case of a homogeneously distributed electron cloud the resulting linear electric space charge field enables the focusing of high intensity heavy ion beams without aberrations. Therefore, the Gabor lens is a promising approach for mass-independent focusing and possible space charge compensation of ion beams. In mid-2012 the performance of a prototype lens has successfully been tested at the GSI High Current Test Injector (HOSTI). GSI and IAP are currently investigating the possible application of such a device for the continuous operation at the High Current Injector (HSI) for FAIR. This contribution will present the results of beam transport experiments at HOSTI as well as the determination of related plasma properties.  
 
THPWO081 Design Options of a High-power Proton Synchrotron for LAGUNA-LBNO dipole, proton, emittance, optics 3948
 
  • Y. Papaphilippou, J. Alabau-Gonzalvo, A. Alekou, F. Antoniou, M. Benedikt, I. Efthymiopoulos, R. Garoby, F. Gerigk, B. Goddard, C. Lazaridis, A.S. Parfenova, E.N. Shaposhnikova, R. Steerenberg
    CERN, Geneva, Switzerland
  
  Design studies have been initiated at CERN, exploring the prospects of future high-power proton beams for producing neutrinos, within the LAGUNA-LBNO project. These studies include the design of a 2 MW high-power proton synchrotron (HP-PS) using the LP-SPL as injector. This paper resumes the design options under study in order to reach this high power, and their implications regarding layout, magnet technology beam loss control and RF considerations. Optics optimization studies are also presented including beam transfer and collimation considerations.  
 
THPWO087 Measurement of Resonant Space Charge Effects in the J-PARC Linac emittance, linac, resonance, simulation 3966
 
  • D.C. Plostinar
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
  • M. Ikegami
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  • Y. Liu, T. Maruta
    KEK/JAEA, Ibaraki-Ken, Japan
  
  Traditionally, high intensity linac designs follow the “equipartitioning condition”, a strict control of the transverse and longitudinal tune ratios throughout the linac that ensures space-charge driven emittance exchange between the longitudinal and transverse planes is minimised. However, equipartitioning imposes strict rules on the linac design, thus limiting the design options and increasing the overall construction cost. More recently, practical tools have been developed that offer guidelines in designing non-equipartitioned linacs, by charting the stable regions in a tune ratio diagram (Hofmann’s Charts). While these stability diagrams have been backed by extensive multiparticle simulations and some experimental evidence, questions still remain regarding the practical consequences of crossing the resonances. In this paper preliminary results are presented from an experimental study conducted in the J-PARC linac, where for the first time we measured both the transverse and longitudinal emittance for different linac working points. A detailed analysis will be presented as well as a discussion on the wider implications of this experiment.