The development of a B-Train system for the CERN proton synchrotron booster

Abstract

In particle accelerators, large electromagnets generate the perpendicular magnetic field that dictates the beam trajectory based on the Lorentz force law. Therefore, precise knowledge of the integrated dipole field produced by these accelerator-magnets is essential for transverse and longitudinal beam control. Consequently, machine operators rely on look-up tables, prediction models, or online measurement systems, called B-Trains, to acquire and distribute the magnetic dipole field in real-time. At the European Organization for Nuclear Research (CERN) accelerator complex, all synchrotrons have been fitted with a new standardised B-Train setup as part of a site-wide consolidation project. This so-called Field In REal-time STreaming from Online Reference-Magnets (FIRESTORM) system has been developed in-house to accommodate the various requirements of the six different machines. One such machine is the Proton Synchrotron Booster (PSB), which was constructed in the 1970s and has undergone several upgrades to meet the ever-increasing demand for higher energies. The most recent upgrade, which occurred in 2020, enabled the PSB to accelerate beams up to 2.0 GeV every 1.2 s. This thesis deals with the work involved in implementing the new B-Train setup for the main-bending-magnets of the PSB. The first part provides an overview of the new FIRESTORM system, detailing its architecture and the operating principle behind several components. The results of a metrological characterisation of its offline performance are also provided, including drift correction, gain calibration and frequency response, in addition to the overall latency of its distribution network. Furthermore, the FIRESTORM system underwent an online qualification campaign to compare its capabilities with the previous Legacy setup. The second part focuses on the calibration process of the induction-coils. It is well known that saturation of the yoke affects the longitudinal field profile of an acceleratormagnet and, by extension, the measurement accuracy. Therefore, this thesis presents a novel measurement method developed for measuring fast-pulsed magnetic fields using the Single Stretched Wire (SSW) system. Being the reference standard, the SSW is commonly used to measure steady-state magnetic fields with absolute precision. This new procedure expands the capabilities of the SSW setup, enabling accurate measurements of timevarying magnetic fields in addition to those at steady-state. Furthermore, this work also proposes a magnetic model that characterises the quasi-static and dynamic responses of iron-dominated bending-magnets. The model presents a method for predicting eddy-currents as a summation of response-functions. Using the PSB main-bending-magnet as a test case, the model successfully replicates the transfer-function with a relative accuracy of less than 200 ppm.