SNS commissioning strategies and tuning algorithms

The Spallation Neutron Source (SNS) [1] has been recently commissioned. Strategies for the initial beam commissioning of the linac and storage ring will be discussed. The superconducting linac (SCL) commissioning posed unique challenges, in particular accommodating an unanticipated wide range of cavity performance. Methods for setting cavity phases and determination of amplitudes will be discussed. The ring commissioning involved the usual establishment of a circulating beam, and then measurement and correction the tune and beta functions, all with a low intensity beam. Then the gradual increase of beam intensity and phase space painting were investigated. The methods to accomplish these tasks will be discussed. Key factors in the successful commissioning were flexibility in accommodating beam conditions that are different from the design, model based applications, good communication between the different groups, and prebeam testing.