Automatic Procedures in the CPS Multiturn Shaving Ejection

Protons are supplied from the CERN PS to the SPS with the multiturn shaving ejection, which is one of the most complex CPS ejection processes. Computer control is not only used to provide the basic switching and adjusting functions, but also to introduce automatic feedback procedures. Whenever the actual state of certain ejection system components, including the proton beam, deviates from the desired state, such procedures are initiated by the computer control system. Automatic recovery of ejection equipment is started after power failures and intermittent faults. The ejected beam intensity is tuned and the shaving ejection efficiency is maximized by closed-loop real-time optimizations. Experience shows that successful procedures of this kind depend strongly upon reliable diagnostic instrumentation and on-line real-time diagnostic software. Fast convergence and safe behaviour are prerequisites. The merits of these automatic procedures are weighed against the considerable implementation effort.