Electron-Cloud Maps for LHC Scrubbing Optimization

Electron-cloud maps as alternative to detailed build-up simulations have already been applied in the past for a few accelerators, e.g. RHIC and the LHC at 7 TeV. We here report on a first application of maps to optimize the “beam scrubbing” of the LHC arcs at injection energy: Maps are used to efficiently determine the optimum bunch filling pattern which maximizes the electron flux on the chamber wall, while respecting constraints on the central cloud density to ensure beam stability. In addition, new features have been explored, e.g. by introducing thresholds which divide regions where either linear maps or cubic maps best describe the build-up and the decay of an electron cloud. In the near future we plan to extend the map formalism to individual slices in a dipole field in order to represent the vertical “stripes”.