Significant experimental and theoretical progress has been
made in the U.S. heavy ion fusion program on high-current sources,
transport, and focusing. Currents over 200 mA have been transported
through a matching section and 10 half-lattice periods with
electric quadrupoles. An experiment shows control of high-beam
current with an aperture, while avoiding secondary electrons.
New theory and simulations of the neutralization of intense
beam space charge with plasma in various focusing chamber
configurations predict that near-emittance-limited beam focal
spot sizes can be obtained even with beam perveance (ratio of
beam space potential to ion energy) >10× higher than
in earlier HIF focusing experiments. Progress in a new focusing
experiment with plasma neutralization up to 10−3
perveance, and designs for a next-step experiment to study beam
brightness evolution from source to target are described.