Investigation of Geometric Variations for Multicell Cavities Using Perturbative Methods

Korinna Brackebusch,Ursula Van Rienen

doi:10.1109/tmag.2015.2487542

Korinna Brackebusch, Ursula Van Rienen

Open Access

https://doi.org/10.1109/tmag.2015.2487542

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Journal: IEEE transactions on magnetics	Publication Date: Mar 1, 2016
Citations: 6	License type: CC BY 3.0

Affiliation: University of Rostock

Abstract

The design of multicell accelerator cavities is a challenging task, since it implies the manipulation of various shape parameters regarding different (partially contradicting) optimization goals. Simulating the electromagnetic characteristics of the full structure depending on various geometric parameters typically involves an enormous computational effort. In most cases, this limits the observed frequency range and the number of optimization passes. For the same reason, the effects of unintended shape deviations are usually excluded from the optimization processes, even though they may be of particular importance for the final design. Perturbative methods offer an efficient approach to tackle this issue. They allow the computation of the eigenmodes and the derived cavity performance parameters for a vast number of cavity designs based on one initial design. In this paper, we investigate the applicability of perturbative methods for performance optimization and simultaneous consideration of the shape variations of a multicell structure.

Highlights

O NE OF the main challenges in designing a superconducting multicell cavity is to provide the best possible beam acceleration and simultaneously guarantee an adequate damping of higher order modes (HOMs) [1]
For a reliable operation of the cavity, it is essential to investigate the characteristics of its HOMs, since they can be excited by a particle beam and seriously impair it
It is evident that C6 and C7 present the candidates with the highest differences

Summary

INTRODUCTION

O NE OF the main challenges in designing a superconducting multicell cavity is to provide the best possible beam acceleration and simultaneously guarantee an adequate damping of higher order modes (HOMs) [1]. This requires an eigenmode analysis of the closed RF structure over a wide frequency range. A further substantial advantage is the fact that the modes of a structure with symmetry-breaking elements (e.g., tuned end-cells) can be derived from the modes of a fully symmetric structure For this purpose, it is only necessary to compute the unperturbed modes for different symmetry settings and to merge them. The shape deformations that may be caused by manufacturing tolerances or operational demands are emulated by a distinct variation in the equator and iris radii of the individual cells

THEORY AND REALIZATION

ACCURACY

RESULTS

CONCLUSION