Design of a compact high current density injector for heavy ion fusion

A compact multiple-beam injector concept is being developed for heavy ion inertial fusion. The design is based on merging high intensity miniature beamlets of a few mA each to form a large beam. In order to minimize emittance growth, the beamlets are kept separated in grids until they are allowed to merge together at 1.2 MeV. With optimized positioning and aiming, the merged beam can quickly match into an electrostatic quadrupole (ESQ) channel. Simulation results have shown that, based on this design, a 1.6 MeV, 0.5 A beam of K/sup +/ ions at the end of the injector has a normalized emittance of approximately 1.0 /spl pi/-mm-mrad which is comparable to that from the previous low current density design. The advantage is a factor of 6 reduction in the combined injector and matching section length.