Advanced Rf-Driven H- Ion Sources At The Sns

The US Spallation Neutron Source* (SNS), will require substantially higher average and pulse H- beam current than can be produced from conventional H- ion sources such as the baseline LBNL-SNS source. IT currents of 70-100 mA with an RMS emittance of 0.20-0.35 pi mm mrad and a similar to 7% duty-factor will be needed for the SNS power upgrade project in 2010. We are therefore investigating several advanced ion source concepts based on RF plasma excitation. First, a generalized discussion of our source development strategy is presented as well as the performance characteristics of a large-plasma-volume, external antenna source based on an Al2O3 plasma chamber. The design and results of computational modeling of a high-power version of this source featuring an AlN plasma chamber is subsequently discussed as well as a high-efficiency extraction system necessary for high-current operation.