The SNS front-end, an injector for a high-power hydrogen-ion accelerator

The Spallation Neutron Source (SNS) is an accelerator-based facility under construction in Oak Ridge, TN, USA, delivering pulsed neutron beams to experimenters. Negative hydrogen ion-beams are generated and preaccelerated in a 2.5 MeV linac injector, or front end (FE), accelerated to 1 GeV energy by a linear accelerator system, converted into protons and accumulated in a ring accelerator, and then directed towards a mercury target to generate the neutrons. The proton beam arrives at the target in bursts of less than 1 μs duration and with more than 1 MW average power. The front end has been built and commissioned by LBNL in Berkeley; shipment to ORNL is essentially complete. This paper provides an overview of FE major design features and experimental results obtained during the commissioning process. The SNS-FE can be viewed as a prototype of a high-current, high duty-factor injector for other accelerator projects or, without the elaborate MEBT, as an independent 2.5 MeV accelerator for various applications.