Feed forward in the LHC
The LHC operational cycle is comprised of several phases such as the ramp, the squeeze and stable beams. During the ramp and squeeze in particular, it has been ob- served that the behaviour of key LHC beam parameters such as tune, orbit and chromaticity is highly reproducible from fill to fill. To reduce the reliance on the crucial feed- back systems, it was decided to perform fill-to-fill feed- forward corrections. The LHC feed-forward application was developed to ease the introduction of corrections to the operational settings. The LHC Feed-Forward software has been used during LHC commissioning and tune and orbit corrections during ramp and squeeze have been suc- cessfully applied. As a result, the required real-time cor- rections for the above parameters have been reduced to a minimum. In parallel, successful trials have been made to apply feedforward corrections before commissioning with beam which are based on M AD - X simulation scans over the unused setting functions. In this paper we present the evolution of feedforward for the LHC and discuss further improvements of this software.