3D-Simulation Studies of SNS Ring Doublet Magnets

The accumulator ring of the Spallation Neutron Source (SNS) at ORNL employs in its straight sections closely packed quadrupole doublet magnets with large aperture of R=15.1 cm and relatively short iron-to-iron distance of 51.4 cm. These quads have much extended fringe field, and magnetic interferences among them in the doublet assemblies is not avoidable. Though each magnet in the assemblies has been individually mapped to high accuracy of lower 10^-4level, the experimental data including the magnet interference effect in the assemblies will not be available. We have performed 3D computing simulations on a quadrupole doublet model in order to assess the degree of the interference and to obtain relevant data for the SNS ring commissioning and operation.