Eigenmode compendium of the third harmonic module of the European X-ray Free Electron Laser
| Autor: | Roger Jones, T. Flisgen, Liangliang Shi, T. Galek, Nicoleta Baboi, Ursula van Rienen, Nirav Joshi, Johann Heller |
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| Jazyk: | angličtina |
| Rok vydání: | 2017 |
| Předmět: |
Nuclear and High Energy Physics
Physics and Astronomy (miscellaneous) Concatenation Degrees of freedom (statistics) 01 natural sciences String (physics) law.invention Resonator law Normal mode 0103 physical sciences ddc:530 lcsh:Nuclear and particle physics. Atomic energy. Radioactivity Innovative Radio Frequency Technologies (RF) [12] 010302 applied physics Physics Coordination and Communication [12.1] 010308 nuclear & particles physics Order (ring theory) Particle accelerator Surfaces and Interfaces Accelerators and Storage Rings 3. Good health Computational physics lcsh:QC770-798 Physics::Accelerator Physics Laser beam quality |
| Zdroj: | Flisgen, T, Heller, J, Galek, T, Shi, L, Joshi, N, Baboi, N, Jones, R M & Rienen, U V 2017, ' Eigenmode compendium of the third harmonic module of the European X-ray Free Electron Laser ', Physical Review Accelerators and Beams, vol. 20, no. 4, 042002 . https://doi.org/10.1103/PhysRevAccelBeams.20.042002 Phys. Rev. Accel. Beams, (2017) pp. 042002 Physical Review Accelerators and Beams, Vol 20, Iss 4, p 042002 (2017) Physical review accelerators and beams 20(4), 042002 (2017). doi:10.1103/PhysRevAccelBeams.20.042002 |
| Popis: | Chains of superconducting radio-frequency resonators are key components of modern particle accelerators such as the European XFEL, which is currently under construction in the north of Germany. In addition to the accelerating mode of the resonators, their beam excited higher order modes are of special interest, because they can harm the beam quality. In contrast to the accelerating mode, these modes are in general not confined within single resonators of the cavity string. For instance, eigenmodes can be localized between adjacent cavities or can be distributed along the entire chain of cavities. Therefore, the full chain has to be considered for a reasonable investigation of its resonant spectra. Accounting for such complex structures is computationally challenging and is therefore often avoided. In this article, the challenge is faced by using the so-called state-space concatenation approach, which is a combination of domain decomposition and model-order reduction. The technique allows for a reduction of the number of degrees of freedom by a factor of $\ensuremath{\approx}\text{ }1.471\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$. The method is employed to generate a compendium of eigenmodes in the chain of third harmonic cavities for the European XFEL. The results are discussed in detail and are compared with experimental measurements. The compendium serves as a reference for experiments (inter alia for diagnostics based on higher order modes) at the third harmonic cavity string of the European XFEL, it allows for qualitative understanding of resonant effects appearing in chains of cavities, and it is meant to be a proof of principle of the state-space concatenation approach to handle very long and complex radio-frequency structures. To the authors' knowledge, it is the first time that a modal compendium of a structure with the given complexity is generated. The article presents geometrical details of the chain, defines quantities relevant to superconducting radio-frequency cavities, and describes the employed computational approach. |
| Databáze: | OpenAIRE |
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