New developments with H- sources

Existing spallation neutron source upgrades, planned spallation neutron sources, and high-energy accelerators for particle physics place demanding requirements on the H- sources. These requirements ask for increased beam currents and duty factor (df) while generally maintaining state-of-the art H- source emittance. A variety of H- sources are being developed to address these challenges. These include volume sources with and without the addition of cesium for enhanced H- production, increased df cesiated H- Penning and magnetron sources, and cesiated surface converter H- sources. Research on surface films of tantalum metal for enhanced volume H- production is also being studied. Innovative plasma production techniques to address the longer df requirement without sacrificing H- source reliability and lifetime will be reviewed. The physical bases, the goals, and perceived challenges will be discussed.