Recent advancements with the H^-injector performance for the Spallation Neutron Source operation and upgrade

The Spallation Neutron Source (SNS) located at the Oak Ridge National Laboratory is an accelerator-based, pulsed neutron facility utilized for a broad range of scientific research and industrial applications. In the past 5 years, the facility has reliably been operated at its baseline design beam power of 1.4 MW, and it is currently undertaking an upgrade to double its power to 2.8 MW. A 65-keV H- injector, which comprises an rf-driven H- ion source and an electrostatic low energy beam transport, delivers the required high-current, time-structured H- beam to the accelerator. The H- injector can reliably provide 50-60 mA beam current at 6% duty-factor (1 ms, 60 Hz) for a 3-4 month service cycle. To ensure sufficient operational margins for the SNS routine operations and ongoing upgrade requirements, the injector system has been continuously improved on a R&D test stand. This paper presents the operational status and recent advancements with the injector system performance including the enhanced ion source beam output capability up to1/4110 mA, the improved ion source plasma ignition reliability using a 27.12-MHz RF system, and the upgraded LEBT beam chopper system etc.