RF behaviour of 3 GHz SCDTL structures

The 3 GHz linac section designed for the low energy (7–65 MeV) part of TOP (Therapy Oncological Protons) linac consists of eight modules of the structure SCDTL (Side Coupled Drift Tube Linac). The non axisymmetric cavities required a full 3D modelling. Electromagnetic calculations carried out by using MAFIA code gave the full mode spectrum, power losses, the coupling coefficients distribution and some indications for the tuning procedure. This paper reports a comparison between the results of this study and some RF measurements on the first module (7–13.4 MeV)