Week 45 - Dedicated MD - SPS

800 MHz LL RF

P. Baudrenghien

The second 800 MHz SPS LLRF MD took place on Nov 5th - 6th 2014 in the SPS, 10:00-01:00. During the first MD (Oct 15th) the system was commissioned at injection energy (fixed RF frequency). The goal of this second MD was to set-up the system through the acceleration ramp. This requires the adjustment and debugging of a series of functionalities, gently adapting the processing to the varying RF frequency. The achievement was the acceleration of a 72 bunches batch, 1E11 p/bunch, with Cav1 controlled by the new LLRF system and Cav2 off (23:30). We have measured the compensation of beam loading for various feedback gains. These first measurements show a good compensation of the low-frequency part of transient beam loading (<3 MHz), consistent with the present regulation BW. We have also measured bunch profiles through the acceleration ramp with the new system. Data being analysed. More measurements of beam “quality” will be done during the third (last) MD on Nov. 26th.