
PIModeStructure (PIMS) cavities will be used in the high energy section of LINAC4 (10^{2}160 MeV). Each cavity is made of 7 coupled cells, operated in the πmode at a resonant frequency of 352.2 MHz. The cell length remains constant for each of the 12 cavities but changes from cavity to cavity to synchronise with the increased beam energy. This paper reports on the tuning process required to get a constant voltage in each cell at the resonant frequency and consisting in remachining to the required level the tuning rings located on each cellwall. An algorithm based on single cell detuning, equivalent circuit simulations and precise 3D simulations for the 3 different cell types of each cavity has been developed and successfully applied to the tuning of the first PIMS cavity. In order to reduce the simulation effort for the remaining 11 cavities, an interpolation algorithm based on 3 cavities has been developed and validated. In a second tuning step, after the electron beam welding of all cells, the final adjustment of singlecell frequencies and field flatness is achieved by cutting the length of one plunger tuner per cell.

