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Veitzer, S.A.

Paper Title Page
TPAT087 The Effect of Magnetic Field Errors on Dynamical Friction in Electron Coolers 4206
 
  • D.L. Bruhwiler, D.T. Abell, R. Busby, S.A. Veitzer
    Tech-X, Boulder, Colorado
  • A.V. Fedotov, V. Litvinenko
    BNL, Upton, Long Island, New York
 
  Funding: Work supported by US DOE grants DE-FG03-01ER83313 and DE-FG03-95ER40926.

A proposed luminosity upgrade to the Relativistic Heavy Ion Collider (RHIC) includes a novel electron cooling section,* which would use ~55 MeV electrons to cool fully-ionized 100 GeV/nucleon gold ions. A strong (1-5 T) solenoidal field will be used to magnetize the electrons and thus enhance the dynamical friction force on the ions. The physics of magnetized friction is being simulated for RHIC parameters, using the VORPAL code.** Most theoretical treatments for magnetized dynamical friction do not consider the effect of magnetic field errors, except in a parametric fashion.*** However, field errors can in some cases dramatically reduce the velocity drag and corresponding cooling rate. We present a simple analytical model for the magnetic field errors, which must be Lorentz transformed into the beam frame for use in our simulations. The simulated dynamical friction for the case of a perfect solenoidal field will be compared with results from this new model, for parameters relevant to RHIC.

*Fedotov et al., Proc. 33rd ICFA Adv. Beam Dynamics Workshop (2004). **Nieter & Cary, J. Comp. Phys. 196 (2004). ***Parkhomchuk, Nucl. Instr. Meth. Phys. Res. A 441 (2000).

 
ROPB006 Filling in the Roadmap for Self-Consistent Electron Cloud and Gas Modeling 525
 
  • J.-L. Vay, M.A. Furman, P.A. Seidl
    LBNL, Berkeley, California
  • R.H. Cohen, K. Covo, A. Friedman, D.P. Grote, A.W. Molvik
    LLNL, Livermore, California
  • P. Stoltz, S.A. Veitzer
    Tech-X, Boulder, Colorado
  • J. Verboncoeur
    UCB, Berkeley, California
 
  Funding: This work was performed under the auspices of the U.S. Department of Energy by University of California, LLNL and LBNL under contracts W-7405-Eng-48, and DE-AC03-76F00098.

Electron clouds and gas pressure rise limit the performance of many major accelerators. A multi-laboratory effort to understand the underlying physics via the combined application of experiment,* theory, and simulation is underway. We present here the status of the simulation capability development, based on a merge of the three-dimensional parallel Particle-In-Cell accelerator code WARP and the electron cloud code POSINST, with additional functionalities.** The development of the new capability follows a "roadmap" describing the different functional modules, and their inter-relationships, that are ultimately needed to reach self-consistency. Newly developed functionalities include a novel particle mover bridging the time scales between electrons and ions motion.*** Samples of applications of the new capability to the modeling of intense charge dominated beams**** and LHC beams***** will be shown as available.

*A.W. Molvik, these proceedings. **J.-L. Vay, Proc. "ECLOUD04," Napa (California), 2004. ***R.H. Cohen, these proceedings. ****P.A. Seidl, these proceedings. *****M.A. Furman, these proceedings.

 
FPAP021 A Cross-Platform Numerical Model of Ion-Wall Collisions 1707
 
  • S.A. Veitzer, P. Stoltz
    Tech-X, Boulder, Colorado
  • R.H. Cohen, A.W. Molvik
    LLNL, Livermore, California
  • J.-L. Vay
    LBNL, Berkeley, California
 
  Ion collisions with beam-pipe walls is a significant source of secondary electron clouds and desorbed neutral gasses in particle accelerators. Ions may reflect from beam-pipe walls and undergo further collisions downstream. These effects can cause beam degradation and are expected to be problematic in the design of heavy ion accelerators. The well-known SRIM code provides physically-based monte carlo simulations of ion-wall collisions. However, it is difficult to interface SRIM with high-performance simulation codes. We present details on the development of a package of Python modules which integrate the simulation of ion-wall interactions at grazing incidences with the high-performance particle-in-cell and electron cloud codes WARP and POSINST. This software package, called GriPY, calculates reflected angles and energies of ions which strike beam-pipe walls at grazing incidences, based upon interpolation of monte carlo statistics generated by benchmark simulations run in SRIM for a variety of relevant incident angles and energies. We present here solutions for 1.8 MeV K+ ions and 1 Gev protons incident on stainless steel.