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Title |
Page |
| 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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| THAW02 |
New experimental measurements of electron clouds in ion beams with large tune depression*
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288 |
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- A. W. Molvik, R. H. Cohen, A. Friedman, M. Kireeff Covo
LLNL, Livermore, California
- F. M. Bieniosek, P. A. Seidl, J.-L. Vay
LBNL, Berkeley, California
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We study electron clouds in high perveance beams (K = 8E-4) with a large tune depression of 0.2 (defined as the ratio of a single particle oscillation response to the applied focusing fields, with and without space charge). These 1 MeV, 180 mA, K+ beams have a beam potential of +2 kV when electron clouds are minimized. Simulation results are discussed in a companion paper [J-L. Vay, this Conference]. We have developed the first diagnostics that quantitatively measure the accumulation of electrons in a beam [M. Kireeff Covo, et al., to be submitted to Phys. Rev. Lett.]. This, together with measurements of electron sources, will enable the electron particle balance to be measured, and electron-trapping efficiencies determined. We measure and simulate ~10 MHz electron oscillations in the last quadrupole magnet when we flood the beam with electrons from an end wall. Experiments where the heavy-ion beam is transported with solenoid magnetic fields, rather than with quadrupole magnetic or electrostatic fields, are being initiated. We will discuss the initial results using electrode sets (in the middle and at the ends of magnets) to either expel or to trap electrons within the magnets.
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