Coupled simulation of 400 MHz elliptical cavity with Soprano and Static Stress Solver of Opera
Published on 17 Apr 2018
Presenter: Anastasia Xydou, CERN
Abstract: The LHC (RF) cavity is a metallic chamber which contains an oscillating electromagnetic field. The cavity is made of copper and the desired superconducting behavior is achieved by sputter-depositing its inner surface with a film of niobium (Nb) with a thickness of the order of 1 m. Each cavity is enveloped in a cryogenic container referred to as a helium tank, containing liquid helium at 4.5 K. On the LHC, the cavities are tuned to oscillate at
400 MHz. During the several steps of the assembly, the center frequency of the cavities is measured. Mechanical tuning is performed to compensate for any frequency shift by applying permanent deformation on the cavities. Coupled electromagnetic with mechanical simulations that can predict the frequency shift at any assembly step as well as at the application of mechanical loads during operation is of high importance. The multi-physics solver of Opera is used to calculate initially the center frequency of a dressed LHC cavity (cavity and He tank) with the Harmonic High Frequency; then with the Static Stress several load cases are examined giving feedback to a second Harmonic HF which calculates the frequency shift.