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Holmes, J.A.

  
Paper Title Page
MOPCH130 Simulations for SNS Ring Commissioning 348
 
  • J.A. Holmes, S.M. Cousineau, S. Henderson, M.A. Plum
    ORNL, Oak Ridge, Tennessee
 
  In preparation for SNS ring commissioning, a number of operational issues have been studied using ORBIT Code simulations. These include beam injection without the use of time-dependent painting, beam accumulation and transport to the extraction dump and to the target, optimal painting schemes for various beam intensities, detailed tracking through the extraction septum with fully correct geometry, quadrupole current constraints in the ring-to-target transfer line (RTBT), and detailed modeling of H minus carbon foil stripping at injection. All these studies incorporated detailed physics including beam-foil interactions, symplectic single particle tracking, space charge and impedances, and losses due to apertures and collimation.  
MOPCH129 Status of the SNS Beam Power Upgrade Project 345
 
  • S. Henderson, A.V. Aleksandrov, D.E. Anderson, S. Assadi, I.E. Campisi, F. Casagrande, M.S. Champion, R.I. Cutler, V.V. Danilov, G.W. Dodson, D.A. Everitt, J. Galambos, J.R. Haines, J.A. Holmes, N. Holtkamp, T. Hunter, D.-O. Jeon, S.-H. Kim, D.C. Lousteau, T.L. Mann, M.P. McCarthy, T. McManamy, G.R. Murdoch, M.A. Plum, B.R. Riemer, M.P. Stockli, D. Stout, R.F. Welton
    ORNL, Oak Ridge, Tennessee
 
  The baseline Spallation Neutron Source (SNS) accelerator complex, consisting 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. Upgrades to the SNS accelerator and target systems to increase the beam power to at least 2 MW, with a design goal of 3 MW, are in the planning stages. The increased SNS beam power can be achieved primarily by increasing the peak H- ion source current from 38 mA to 59 mA, installing additional superconducting cryomodules to increase the final linac beam energy to 1.3 GeV, and modifying injection and extraction hardware in the ring to handle the increased beam energy. The mercury target power handling capability will be increased to 2 MW or greater by i) mitigating cavitation damage to the target container through improved materials/surface treatments, and introducing a fine dispersion of gas bubbles in the mercury, and ii) upgrading the proton beam window, inner reflector plug and moderators. The upgrade beam parameters will be presented and the required hardware modifications will be described.  
MOPCH131 SNS Ring Commissioning Results 351
 
  • M.A. Plum, A.V. Aleksandrov, S. Assadi, W. Blokland, I.E. Campisi, P. Chu, S.M. Cousineau, V.V. Danilov, C. Deibele, G.W. Dodson, J. Galambos, M. Giannella, S. Henderson, J.A. Holmes, D.-O. Jeon, S.-H. Kim, C.D. Long, T.A. Pelaia, T.J. Shea, A.P. Shishlo, Y. Zhang
    ORNL, Oak Ridge, Tennessee
 
  The Spallation Neutron Source (SNS) comprises a 1.5-MW, 60-Hz, 1-GeV linac, an accumulator ring, associated beam lines, and a spallation neutron target. Construction began in 1999 and the project is on track to be completed in June 2006. By September 2005 the facility was commissioned up through the end of the superconducting linac, and in January 2006 commissioning began on the High Energy Beam Transport beam line, the accumulator ring, and the Ring to Target Beam Transport beam line up to the Extraction Beam Dump. In this paper we will discuss early results from ring commissioning including a comparison of achieved vs. design beam machine parameters and the maximum beam intensity achieved to date.  
TUOCFI02 First Results of SNS Laser Stripping Experiment 980
 
  • V.V. Danilov, A.V. Aleksandrov, S. Assadi, J. Barhen, Y. Braiman, D.L. Brown, W. Grice, S. Henderson, J.A. Holmes, Y. Liu, A.P. Shishlo
    ORNL, Oak Ridge, Tennessee
 
  Thin carbon foils are used as strippers for charge exchange injection into high intensity proton rings. However, the stripping foils become radioactive and produce uncontrolled beam loss, which is one of the main factors limiting beam power in high intensity proton rings. Recently, we presented a scheme for laser stripping of an H- beam for the SNS ring. First, H- atoms are converted to H0 by a magnetic field, then H0 atoms are excited from the ground state to the upper levels by a laser, and the excited states are converted to protons by a magnetic field. This paper presents first results of the SNS laser stripping proof-of-principle experiment. The experimental setup is described, and possible explanations of the data are discussed.  
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THOAFI01 The Development of Computational Tools for Halo Analysis and Study of Halo Growth in the Spallation Neutron Source Linear Accelerator 2768
 
  • D.A. Bartkoski, A.V. Aleksandrov, S.M. Cousineau, S. Henderson, J.A. Holmes
    ORNL, Oak Ridge, Tennessee
 
  Computational tools have been developed to quantify the halo in a beam by analyzing beam profiles and identifying the halo particles using the Gaussian area ratio and kurtosis methods. Simulations of various injection quadrupole magnet configurations using three types of initial simulated distributions, along with an analysis of their phase space and rms properties, provides insight into the development of halo in the Spallation Neurton Source linear accelerator. Finally, comparisons with machine beam profile data, taken at the same conditions as that of the simulated data, show how accurately the simulations model the beam and its halo development and provide a better understanding of the best machine configuration with which to minimize beam halo and losses.  
slides icon Transparencies
THPCH025 Electron Cloud Self-consistent Simulations for the SNS Ring 2832
 
  • A.P. Shishlo, S.M. Cousineau, V.V. Danilov, S. Henderson, J.A. Holmes, M.A. Plum
    ORNL, Oak Ridge, Tennessee
 
  The electron cloud dynamics is simulated for the Spallation Neutron Source ring using the self-consistent electron-cloud model for long-bunched proton beams implemented in the ORBIT code. These simulations feature simultaneous calculations of the dynamics of the proton bunch and of the electron cloud, including electron multipacting using a realistic secondary emission surface model. The frequency spectra and growth rates of the proton bunch transverse instability are studied as functions of the RF cavity voltage. The effectiveness of an electron-cloud instability suppression system is also studied using an ORBIT model of the real feedback system. SNS is a collaboration of six US National Laboratories: Argonne National Laboratory (ANL), Brookhaven National Laboratory (BNL), Thomas Jefferson National Accelerator Facility (TJNAF), Los Alamos National Laboratory (LANL), Lawrence Berkeley National Laboratory (LBNL), and Oak Ridge National Laboratory (ORNL).  
WEPCH141 Accelerator Physics Code Web Repository 2254
 
  • F. Zimmermann, R. Basset, E. Benedetto, U. Dorda, M. Giovannozzi, Y. Papaphilippou, T. Pieloni, F. Ruggiero, G. Rumolo, F. Schmidt, E. Todesco
    CERN, Geneva
  • D.T. Abell
    Tech-X, Boulder, Colorado
  • R. Bartolini
    Diamond, Oxfordshire
  • O. Boine-Frankenheim, G. Franchetti, I. Hofmann
    GSI, Darmstadt
  • Y. Cai, M.T.F. Pivi
    SLAC, Menlo Park, California
  • Y.H. Chin, K. Ohmi, K. Oide
    KEK, Ibaraki
  • S.M. Cousineau, V.V. Danilov, J.A. Holmes, A.P. Shishlo
    ORNL, Oak Ridge, Tennessee
  • L. Farvacque
    ESRF, Grenoble
  • A. Friedman
    LLNL, Livermore, California
  • M.A. Furman, D.P. Grote, J. Qiang, G.L. Sabbi, P.A. Seidl, J.-L. Vay
    LBNL, Berkeley, California
  • D. Kaltchev
    TRIUMF, Vancouver
  • T.C. Katsouleas
    USC, Los Angeles, California
  • E.-S. Kim
    PAL, Pohang, Kyungbuk
  • S. Machida
    CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon
  • J. Payet
    CEA, Gif-sur-Yvette
  • T. Sen
    Fermilab, Batavia, Illinois
  • J. Wei
    BNL, Upton, Long Island, New York
  • B. Zotter
    Honorary CERN Staff Member, Grand-Saconnex
 
  In the framework of the CARE HHH European Network, we have developed a web-based dynamic accelerator-physics code repository. We describe the design, structure and contents of this web repository, illustrate its usage, and discuss our future plans.