| Paper | Title | Page |
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| WEAY04 | Analysis of the magnetized friction force | 210 |
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| A comprehensive examination of theoretical models for the friction force, in use by the electron cooling community, was performed. Here, we present our insights about the models gained as a result of comparison between the friction force formulas and direct numerical simulations, as well as studies of the cooling process as a whole. | ||
| WEBX03 | Modeling of Non-linear Effects in RF Cavities | 0 |
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Emerging accelerator applications require electron beam radii comparable to RF cavity apertures, placing more stringent demands on the modeling of particle motion in RF cavities using map-based techniques. High-gradient cavities and cavities with significant axial asymmetries also demand improvements in modeling capabilities. A new method has been developed for computing high-order nonlinear maps for arbitrary RF cavities*. It has been implemented through fifth order in MaryLie/IMPACT, so simulations can include the effects of space-charge. We describe this new approach and present comparisons with more traditional approaches.
* D. T. Abell, submitted to PRST-AB. |
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| WEBY05 | Simulating dynamical friction in wiggler-based high-energy electron coolers, including finite-time effects | 0 |
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| The proposed RHIC-II luminosity upgrade includes a novel electron cooling section, using ~55 MeV electrons to cool fully-ionized gold. We present simulations of the dynamical friction force exerted on the Au ions. Rather than a strong solenoid, a long helical wiggler magnet is used to provide focusing and suppress recombination. In the rest frame of the relativistic electron and ion beams, with non-relativistic motion and electrostatic fields, the Lorentz transformed wiggler field yields strong, rapidly-varying electric fields. The VORPAL simulation framework applies a semi-analytic binary collision algorithm, in which ion-electron collisions are modeled pairwise. This model is combined with standard particle-in-cell (PIC) techniques, through an operator-splitting approach, to include the effects of external fields. Charge shielding due to electron-electron interactions is also included via PIC. Simulated friction results are compared with BETACOOL, which integrates the standard unmagnetized formulas. With finite interaction times and electron wiggle motion correctly included, we find good agreement with VORPAL. |