| Paper | Title | Page |
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| WEPCH120 | Simulation of 3D Space-charge Fields of Bunches in a Beam Pipe of Elliptical Shape | 2200 |
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| Recent applications in accelerator design require precise 3D calculations of space-charge fields of bunches of charged particles additionally taking into account the shape of the beam pipe. An actual problem of this kind is the simulation of e-clouds in damping rings. In this paper a simulation tool for 3D space-charge fields is presented where a beam pipe with an arbitrary elliptical shape is assumed. The discretization of the Poisson equation by the method of finite differences on a Cartesian grid is performed having the space charge field solved only in the points inside the elliptical cross-section of the beam pipe taking care of the conducting boundaries of the pipe. The new routine will be implemented in the tracking code ASTRA. Numerical examples demonstrate the performance of the solution strategy underling the new routine. Further tracking results with the new method are compared to established space-charge algorithms such as the FFT-approach. | ||
| WEPCH121 | 3D Space-charge Calculations for Bunches in the Tracking Code ASTRA | 2203 |
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| Precise and fast 3D space-charge calculations for bunches of charged particles are of growing importance in recent accelerator designs. One of the possible approaches is the particle-mesh method computing the potential of the bunch in the rest frame by means of Poisson's equation. In that, the charge of the particles are distributed on a mesh. Fast methods for solving Poisson's equation are the direct solution applying Fast Fourier Methods (FFT) and a finite difference discretization combined with a multigrid method for solving the resulting linear system of equations. Both approaches have been implemented in the tracking code ASTRA. In this paper the properties of these two algorithms are discussed. Numerical examples will demonstrate the advantages and disadvantages of each method, respectively. | ||
| WEPCH122 | 2D Wake Field Calculations of Tapered Structures with Different FDTD Discretization Schemes | 2206 |
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The continual performance improvement of particle accelerators requires advanced prediction of parasitic wake field effects, even in structures of comparatively weak influence like tapers. In the case of smooth tapered components, even well established codes like MAFIA* demonstrate strong discretization dependency of the results or solver instabilities, making them not reliable in such applications. Grid dispersion is assumed to generate this failure. In Ref.** an alternative discretization scheme is described, using a homogeneous rotated mesh intended to eliminate such grid dispersion effects. In order to study the dependence on the discretization applied, we use this scheme to calculate wake fields in prototype taper structures of rotational symmetry. Furthermore a comparison is provided with the results of a non-rotated mesh, MAFIA runs and - so far applicable - analytical approaches.
*MAFIA V4.107: CST GmbH, Bad Nauheimer Str. 19, D-64289 Darmstadt**R. Hampel et al. New discretization scheme for wake field computation in cylindrically symmetric structure. Proc. EPAC'04, pp 2559 |