Development of the next generation H − ion source for the LANSCE facility

The upgrade of the Los Alamos Neutron Science Center (LANSCE) will require an ion source producing high intensity H − beams. The new LANSCE source in particular will need to generate 40 mA of H − beam current at a duty factor of 12% (1 ms pulse at 120 Hz). To achieve this, the present Los Alamos results were first reproduced employing a prototype surface conversion source similar to the existing LANSCE source. Using these results as a benchmark for further testing, it was discovered that by moving the filament cathode into the chamber’s cusp-field, the H − ion yield was enhanced. Considering this result, two extension chambers were added with movable magnetic filters at each end of the source to further improve the H − beam current. In addition, construction has been started on a new prototype axial source which will enable more plasma ions to funnel across the filter field into the central region where the converter is located. Results of the magnetic filter operation as well as the new axial source design will be presented.