Beam scrubbing strategy for electron-cloud suppression in the Spallation neutron source ring

Electron cloud is still an unsettled issue for the high intensity SNS storage ring. Studies are undergoing, especially on the electron multipacting condition, beam instability threshold, electron density and the electron dose on the wall. It has been simulated that the electron multipacting may generate very large electron dose that the pressure rise might become unacceptable. Chamber sections with high secondary electron yield and/or locations having large numbers of primary electrons, such as the injection region or the collimation area, are likely to have higher pressure rise. Beam scrubbing is proposed as one of the principle mitigations for the electron multipacting problem in the SNS. In this article, experiments of the beam scrubbing on existing machines will be reviewed, and specifics of the will be discussed