Ion Sources and Injectors for Hif Induction Linacs

For heavy ion fusion (HIF) induction linac drivers, a typical injector requires total beam current of 50-100 A and is comprised of many individual beams of 0.5-1.0 A each. As a step towards developing a full ion driver for inertial fusion energy (IFE) power plants, an Integrated Research Experiment (IRE) will be proposed within a few years [1]. The IRE will have a linac of more than 150 MeV and beam current about 18 A (ion mass 39). At present, a compact multiple-beam injector is being developed to meet the IRE specifications. In our design, about 100 miniature beamlets (of a few mA each) will be merged to form each 0.5 A beam at the matching section. The beamlets have current density up to 100 mA/cm2 at the ion source (as opposed to 3.5 mA/cm2 used in previous low current density large beam designs). With optimized positioning and aiming, the miniature beamlets can quickly merge and match into an ESQ channel thus minimizing the matching section size requirement. Simulation results have shown that when the beamlet current is small and the number of beamlets are large, the emittance of a 1.6 MeV, 0.5 A beam (after merging) at the end of the injector is 1.0 π mm-mrad.