Requirements for real time correction of decay and snapback in the LHC superconducting magnets

The LHC superconducting magnets will have field errors with both static and dynamic components. These will affect the key beam parameters such as energy, tune, orbit and chromaticity. The allowed variations in these beam parameters during injection and the energy ramp are extremely small. The required compensation of certain multipole components of the field errors can probably not be performed with feed-forward correction alone. Real time control of beam parameters via appropriate correction magnets is therefore proposed. This paper outlines the requirements for such real time control