Mechanism of electron cloud clearing in the accumulator ring of the Spallation Neutron Source

Abstract

We describe a mechanism using clearing electrodes and solenoids to remove the electron cloud in the Spallation Neutron Source’s accumulator ring. Simulation indicates that strong multipacting could happen at median clearing fields. A similar phenomenon was reported in an experimental study at Los Alamos Laboratory’s Proton Storage Ring. A weak solenoid is proven to be a good remedy for suppressing multipacting by confining electrons near the chamber wall’s surfaces. We investigated the clearing mechanism using both electrodes and solenoids.