MULTIPACTING IN HOM COUPLERS AT THE 1.3GHz 9-CELL TESLA TYPE SRF CAVITY

During the XFEL [1] prototype module tests on the module test stand at DESY [2], [3], [4] RF power measurement anomaly on the higher order mode (HOM) couplers at the cavity operating frequency was detected and investigated. HOM coupler multipacting, predicted by the analytical simulations [5], was found to be the source of the anomalous signal peak. TESLA type SRF cavity HOM coupler multipacting simulations and observations are presented, compared and discussed.