An Automatic Cavity Phasing Routine for HIE-ISOLDE

The broad experimental programme at ISOLDE means that the same beam species and energy are rarely studied twice and the cavities of the linac must be scaled or re-phased for each experiment. In order to expedite machine set-up a software routine that automatically calculates the cavity phases has been developed. The routine takes as input the beam parameters, the state of the linac (the available cavities and their condition) and the desired final energy, and calculates the necessary phases and voltages to be applied to each cavity. Different algorithms for partitioning the voltage were implemented. A beam dynamics error study was carried out in order to better understand the challenges facing the automatic phasing routine. The effects of a variety of different errors on the efficacy of the phasing application were studied, leading to a specification of the tolerances required for the calibration of the rf system and the accuracy of the survey system that monitors the positions of the cavities.