Incremental performance improvements for a surface-convergency H- ion source

We discuss some of the interventions on LANSCE's surface-conversion negative-hydrogen ion sources to increase reliability; lifetime and output without any major re-design of the machine. LANSCE's source presently delivers a baseline 16 mA, 60 Hz, 12% duty factor beam. We describe how better quality control and processing of tungsten filaments allow the comfortable completion of 28-day run cycles, how improved temperature control of the ion source body yields an increased H- output, how higher input power through an additional filament allows operations at plasma densities while maintaining the filament lifetime and how adequate electrode biasing inside the source provide some control over the beam Twiss parameters on exit.