A new tuning procedure for the DTL RF field pattern

The DTL tank is a multi-cell cavity. In a fabricated tank, the measured average axial field Eo for each cell may obviously deviate from the designed value. It is generally thought the deviation is due to the errors in fabrication and assembly. But it is not always true. In this paper, it is shown that the deviation may already exist before fabrication in some cases. It is partly due to the imperfection of the current design procedures. A new design method is introduced to reduce the deviation in the design stage.