SOLEIL, Gif-sur-Yvette
Beam orbit stability is a crucial parameter for 3rd generation light sources in order to achieve their optimum performance. Sub-micron stability is now a common requirement for vertical beam position. To reach such performance, Global Orbit Feedback Systems are mandatory. This paper describes the different design approaches for Global Orbit Feedback Systems. A few machines can use a single set of strong correctors. Most machines have their strong corrector bandwidth limited by eddy currents in aluminium vacuum chamber, or power-supplies speed or digitization granularity. Then, a second set of fast correctors is required for high frequency correction. But Fast and Slow Orbit Feedback Systems cannot work together with a common frequency range, they fight each other. An earlier solution has been to separate fast and slow systems by a frequency deadband. This approach does not allow correcting efficiently the orbit shift due to the gap movements of the increasingly sophisticated insertion devices that are installed on new machines. The different solutions that have been recently implemented are reviewed.
