Week 42 - Dedicated MD - SPS

800 MHz LLRF commissioning

P. Baudrenghien, T. Bohl, J. Galindo, G. Hagmann, F. Killing, M. Ojeda, H. Timko  BE-RF

This was the first MD to upgrade the LLRF on the SPS 800 MHz system. The news electronics is installed on Cavity 1. The first 1-2 hours were used to re-condition the cavity. We then made calibration of power chain (from LLRF to IOT output) and Antenna chain (from accelerating voltage to measured signal). We adjusted the LLRF setting and closed the feedback. From then on, the accelerating voltage was controlled by the new LLRF. The system was set at 700 kV, very stable and with little RF noise. We checked the tracking of the 800 MHz voltage with the 200 MHz. We then injected a 2 microsec long batch and made acquisitions of the uncompensated beam loading versus the feedback gain. As we worked at 26 GeV only (long bunches) the beam loading was very small at 800 MHz and the measurements are not precise enough to derive quantitative results.

Status: The system has been commissioned at 26 GeV. We will ramp the RF and beam in the next MD.