Mechanical design of the prototype H- ion source for the Spallation Neutron Source

The mechanical design of the prototype H^- ion source for the Spallation Neutron Source (SNS) is presented. Experience obtained in the ongoing SNS R&D program is being utilized in the current design. The physics design parameters require a 2 MHz RF-driven multicusp ion source operated at 50kW, pulsed (6% duty factor) RF-power. The four major components (plasma-generator, cesium collar, outlet electrode, the source tilt mechanism) of the mechanical packaging of the ion source are presented in details. The mechanical design has the unique capability of tilting the ion source in one plane in order to compensate the H^- ion beam deflection caused by a strong magnetic field across the outlet aperture. This B-field deflects electrons in the extracted beam back to the outlet electrode. An articulating strut system will provide accurate control over the adjustable tilt angle. This new ion source design will provide easy serviceability of maintenance parts like the RF-antenna and the cesium dispensing system