An electrostatic LEBT for a low-emittance injector: transport and focusing of a high-brightness H− beam from a magnetron ion source

In the context of developing an efficient low-energy beam transport (LEBT) system for a low-emittance injector the problem of transport and matching of a 30 mA, 35 kV H− beam from a magnetron-type ion source is studied; the analysis is done incorporating important experimental constraints. A 30 cm-long LEBT, consisting of six electrostatic quadrupole lenses and a short einzel lens, is designed. Its control parameters are optimized to achieve a solution which matches with the acceptance of a small-aperture radio-frequency quadrupole (RFQ) accelerator. The results of beam dynamics calculations are discussed, and the key issues for emittance growth and its control are acknowledged.