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Macek, R.J.

Paper Title Page
ROPB010 Self-Consistent Electron-Cloud Simulation for Long Proton Bunches 722
  • A.P. Shishlo, S.M. Cousineau, V.V. Danilov, S. Henderson, J.A. Holmes, Y. Sato
    ORNL, Oak Ridge, Tennessee
  • S.-Y. Lee
    IUCF, Bloomington, Indiana
  • R.J. Macek
    LANL, Los Alamos, New Mexico
  Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos, and Oak Ridge.

The results of numerical electron-cloud simulations for long-bunch proton beams in accumulator rings are presented and compared with data from the Proton Storage Ring at LANL. The frequency spectra and growth rate of proton-bunch transverse instabilities are studied as functions of the RF cavity voltage, external magnetic fields, beam pipe surface properties, and other factors. We used the recently developed electron-cloud module in the ORBIT code. The model includes a fully self-consistent coupled treatment of the "proton bunch – electron-cloud" dynamics and the multipacting process with a realistic secondary emission surface model. Realistic lattices and proton bunch distributions are used. The efficiency of electron-cloud instability suppression has also been studied using a new ORBIT model.

FPAE011 8 GeV H- Ions: Transport and Injection 1222
  • W. Chou, A.I. Drozhdin, C. Hill, M.A. Kostin, J.-F. Ostiguy, Z. Tang
    Fermilab, Batavia, Illinois
  • H.C. Bryant
    UNM, Albuquerque, New Mexico
  • R.J. Macek
    LANL, Los Alamos, New Mexico
  • G. Rees
    CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon
  • P.S. Yoon
    Rochester University, Rochester, New York
  Funding: Work supported by the Universities Research Association, INC. under contract with the U.S. Department of Energy NO. DE-AC02-76CH03000.

Fermilab is working on the design of an 8 GeV superconducting RF H- linac called the Proton Driver. The energy of the H- beam is an order of magnitude higher than any existing H- beams. This brings up a number of new challenges to the transport, stripping and injection into the next machine (the Main Injector), such as blackbody radiation stripping, magnetic field and residual gas stripping, Stark states of hydrogen atoms, foil stripping efficiency, single and multiple Coulomb scattering, energy deposition, foil heating and stress, radiation activation, collimation, jitter correction, etc. This paper will give a summary of these studies.*

*For details the reader is referred to FERMILAB-TM-2285-AD-T.

RPAT038 Diagnostic for Electron Clouds Trapped in Quadrupoles 2547
  • R.J. Macek, A. A. Browman
    TechSource, Santa Fe, New Mexico
  Funding: Work supported by a DOE SBIR Phase I grant DE-FG02-04ER84105.

Simulations have indicated that electron clouds generated by beam-induced multipactor can be trapped in the mirror-like fields of magnetic quadrupoles and thereby contribute significantly to the electron cloud buildup in high intensity accelerators and storage rings. This could be the most important source of electrons driving the two-stream (e-p) instability at the Los Alamos PSR and may also play a significant role in electron cloud effects at some of the new high intensity accelerator projects. We will describe the physics design and optimization of an electron-sweeping detector designed to measure the trapped electrons at various times after the beam pulse has passed. The instrument can also serve as an electro-magnetically shielded detector providing a signal obtained from electrons striking the wall during the passage of beam bunches.