Design and validation methodology of the control system for a particle beam size measurement instrument at the CERN laboratory

Abstract

A new generation of the Beam Wire Scanner (BWS) instrument is being developed for the Large Hadron Collider (LHC) and its injector chain at the European Organization for Nuclear Research (CERN). This is an electro-mechanical system based on a Permanent Magnet Synchronous Motor (PMSM), a robust resolver and a high precision optical encoder. This system is located in underground installations and has to withstand large irradiation levels provoked by particle beams. The control electronics is situated away from it to avoid the destructive impact of ionizing particles, introducing long distances of up to 250m for powering and measuring the system. Challenges arise when imposing large acceleration to obtain a scanning speed of the wire of no less than 20ms−1 and above, with a target position accuracy of 5µm rms. This paper details the methodology of the system and control design, which includes performance evaluation benchmark at different design stages and the target electronics development. Finally, the first field results performed inside the Super Proton Synchrotron (SPS) accelerator machine are presented.