A multi-beamlet injector for heavy ion fusion: Experiments and modeling

We have performed experiments and modeling to evaluate a proposed merging beamlet approach for use in a compact high-brightness Heavy Ion Fusion injector. We used an rf plasma source to produce the initial beamlets. An extraction current density of 100 mA/cm² was achieved, and the thermal temperature of the ions was below 1 eV. An array of converging beamlets was used to produce a beam with the envelope radius, convergence, and ellipticity matched to an electrostatic quadrupole channel. Experimental results were in good quantitative agreement with computer simulations and have demonstrated the feasibility of this concept. The size of a driver-scale injector system using this approach will be several times smaller than one designed using traditional single large-aperture beams. The success of this experiment has possible significant economical and technical impacts on the architecture of HIF drivers.