| Paper |
Title |
Page |
| TUAX05 |
Studies of e-cloud build up for the FNAL main injector and for the LHC
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102 |
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- M. A. Furman
LBNL, Berkeley, California
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We present a summary of recent simulation studies of the electron-cloud (EC) build-up for the FNAL Main Injector and for the LHC. In the first case we pay particular attention to the dependence on bunch intensity (Nb) at injection energy, and we focus on the dipole magnets and field-free regions. The saturated value of the average EC density shows a clear threshold in Nb beyond which the beam will be approximately neutralized on average. For the case of the LHC we limit our discussion to arc dipoles at collision energy, and bunch spacings tb=25 ns or tb=75 ns. The main variables exercised in this study are Nb and the peak value of the secondary emission yield (dmax). For tb=25 ns we conclude that the EC power deposition is comfortably below the available cooling capacity of the cryogenic system if dmax is below ~1.2 at nominal Nb. For tb=75 ns, the EC power deposition is insignificant. As a byproduct of this exercise, we reach a detailed understanding of the significant role played by the backscattered secondary electrons.
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| THAW01 |
New simulation capabilities of electron clouds in ion beams with large tune depression
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279 |
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- J.-L. Vay, M. A. Furman, P. A. Seidl
LBNL, Berkeley, California
- R. H. Cohen, A. Friedman, D. P. Grote, M. Kireeff Covo, A. W. Molvik
LLNL, Livermore, California
- P. Stoltz, S. A. Veitzer
Tech-X, Boulder, Colorado
- J. Verboncoeur
UCB, Berkeley, California
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We have developed a new, comprehensive set of simulation tools aimed at modeling the interaction of intense ion beams and electron clouds (e-clouds). The set contains the 3-D accelerator PIC code WARP and the 2-D “slice” e-cloud code POSINST [M. Furman, this workshop], as well as a merger of the two, augmented by new modules for impact ionization and neutral gas generation. The new capability runs on workstations or parallel supercomputers and contains advanced features such as mesh refinement, disparate adaptive time stepping, and a new “drift-Lorentz” particle mover for tracking charged particles in magnetic fields using large time steps. It is being applied to the modeling of ion beams (1 MeV, 180 mA, K+) for heavy ion inertial fusion and warm dense matter studies, as they interact with electron clouds in the High-Current Experiment (HCX) [experimental results discussed by A. Molvik, this workshop]. We will describe the capabilities and simulation results with detailed comparisons against the HCX experiment, as well as their application (in a different regime) to the modeling of e-clouds in the Large Hadron Collider (LHC).
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