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| WEPOY004 | Integrated Green Function for Charged Particle moving along Bending Orbit | 2997 |
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| Electro-magnetic field for moving charged particle is given by Liennard-Wiechert potential. The field contains high frequency component corresponding to synchrotron light, ω=3cγ3/(2ρ). The frequency is too high to study beam behavior generally. Green function integrated over beam distribution and/or over in a region σx/nx× σy/ny× σz/nz (nxyz ∼ 10) is useful to study instability and emittance growth of the beam. The green function is regarded as the wake field for coherent synchrotron radiation in three dimension space. | ||
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| WEPOY007 | Simulation of Electromagnetic Scattering Through the E-XFEL Third Harmonic Cavity Module | 3001 |
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Funding: The work is part of EuCARD-2, partly funded by the European Commission, GA 31245. N.~Y.~Joshi receives additional funding from The Cockcroft Institute of Science and Technology. The European-XFEL is being fabricated in Hamburg to serve as an X-ray Free Electron Laser (FEL) light source. The electron beam will be accelerated through linacs consisting of 1.3 GHz superconducting cavities along a length of 2.1 km. In addition, third harmonic cavities will improve the quality of the beam by linearising the field profile and hence reducing the energy spread. There are eight 3.9 GHz cavities within a single module AH1 of E-XFEL. The beam-excited electromagnetic (EM) field in these cavities can be decomposed into a series of eigenmodes. These modes are, in general, not cut-off between one cavity and the next, as they are able to couple to each other throughout the module. Here for the first time, we evaluate components of the scattering matrix for module AH1. This is a computationally expensive system, and hence we employ a Generalized Scattering Matrix (GSM) technique to allow rapid computation with reduced memory requirements. Verification is provided on reduced structures, which are compared to finite element mesh-based codes. The mode spectrum for the dipole bands of interest in an eight-cavity chain have been calculated and external Q factors for the modes are derived. |
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| WEPOY060 | YACS - Progression Towards Isoparametric 2.5D Finite Elements | 3135 |
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Funding: Work supported by the BMBF under contract no. 05K13PEB. YACS is a 2.5D finite element method solver capable of solving for the full 3D eigenfrequency spectra of resonant axisymmetric structures while reducing the computational problem to a 2D rotation plane. Prior studies and benchmarks, comparing YACS to well known commercial 3D and 2D applications, already demonstrated its capabilities of performing fast optimizations of geometries, due to its minimal computational overhead. However, because of the first order elements and basis functions used for approximation of the domain and field, this solving speed advantage vastly diminishes when targeting higher accuracies. In order to circumvent these issues, YACS was upgraded to support arbitrary order basis functions and curved meshes, leading to, but not limited to, isoparametric finite elements. This led to distinct performance and convergence improvements, especially when considering curved geometries, ideally representable by a polynomial mapping, e.g. when choosing a cavity geometry parametrization based on splines. |
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