| Paper | Title | Page |
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| TUPC20 | The SOLEIL BPM and Orbit Feedback Systems | 189 |
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| SOLEIL is a third generation light source built in France, near Paris. Its BPM system is important for machine studies and for delivering stable beams to the users. A beam stable to 1/10th of the dimensions requires submicron stability in the vertical plane. The monitors, anchored either to the girders or to the ground, are fixed points of the vacuum chamber. Bellows avoid transverse drifts due to mechanical stress. The electronics design was driven by combined efforts through an active communication between accelerator labs (SOLEIL at first, later joined by DIAMOND) and Instrumentation Technologies. The result is the “Libera Electron” beam position processor. It combines a 0.2μm rms resolution and micron level stability for beam delivery with accurate turn-by-turn measurements (3μm resolution at 0.8MHz) for machine commissioning and beam physics studies. It also features position interlock, tune measurement, and postmortem capabilities. A Slow Orbit Feedback for correcting low frequency drifts (0 to 0.1Hz) is currently in operation. The Fast Orbit Feedback to be implemented soon will suppress higher frequency perturbations up to 100Hz. | ||
| WEPC04 | Transverse Feedback Development at SOLEIL | 316 |
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The SOLEIL ring is planned to operate in both multibunch and high current per bunch modes. However, the small vertical chamber aperture around the SOLEIL ring enhances the transverse impedance both in its resistive-wall and broadband content, resulting in instabilities that appear at relatively low current compared to the desired values. A decision was therefore taken to install a digital bunch-by-bunch feedback system, with an aim to make it operational from the beginning of the user operation. The system implemented comprises components developed elsewhere, particularly the FPGA processor of Spring-8, chosen among different possible solutions. Using a BPM and a stripline in the diagonal mode, a single unit of the FPGA processor board has shown to successfully suppress resistive-wall and ion induced instabilities in either one or both transverse planes up to 300 mA. The paper discusses the system characteristics including striplines whose shunt impedance was maximised by keeping the coupling impedance small*, the obtained performance as well as future extensions to overcome the encountered limitations.
* C. Mariette ID1209 |