HOM Suppression Improvement for Mass Production of EXFEL Cavities at RI

Alexey Sulimov, Michael Pekeler, Jan-Hendrik Thie, Daniel Trompetter, Schaa, Volker RW (Ed.), Yamazaki, Yoshishige (Ed.), Facco, Alberto (Ed.), McCausey, Amy (Ed.)
During cold RF tests of the European XFEL (EXFEL) cavities at DESY it was observed that the damping of the second monopole mode (TM011) showed the largest variation, which was sometimes up to 2-3 times lower than the originally allowed limit. It was concluded that this TM011-damping degradation was caused by cavity geometry deviation within the specified mechanical tolerances. The particular influence of different mechanical parameters was analyzed and additional RF measurements were carried
more » ... nts were carried out to find the most critical geometry parameters. Stability of the equator welding and regularity of chemical treatment were investigated for different cavity cells. In spite of the high fabrication rate during EXFEL cavity mass production the TM011 suppression was improved to an acceptable level.
doi:10.18429/jacow-linac2016-thplr018 fatcat:z3q2odd34vcndnms3xj2elrxyy