HOM study and parameter calculation of the TESLA cavity model

Abstract

The Superconducting Proton Linac (SPL) is the project for a superconducting, high current H-accelerator at CERN. To find dangerous higher order modes (HOMs) in the SPL superconducting cavities, simulation and analysis for the cavity model using simulation tools are necessary. The existing TESLA 9-cell cavity geometry data have been used for the initial construction of the models in HFSS. Monopole, dipole and quadrupole modes have been obtained by applying different symmetry boundaries on various cavity models. In calculation, scripting language in HFSS was used to create scripts to automatically calculate the parameters of modes in these cavity models (these scripts are also available in other cavities with different cell numbers and geometric structures). The results calculated automatically are then compared with the values given in the TESLA paper. The optimized cavity model with the minimum error will be taken as the base for further simulation of the SPL cavities.

Influence of higher order modes on the beam stability in the high power superconducting proton linac

“…The exact geometries are listed in Appendix A. A HOM analysis was done with HFSS TM v11 [37], using postprocessing scripts [38]. The TM monopole [39] and dipole modes with the highest ðR=QÞ n values, found for both cavity families in the considered velocity range, are listed in Tables III and IV.…”