Lithium ion beam divergence on SABRE extraction ion diode experiments

Summary form only given. Intense lithium beams are of particular interest for light ion inertial confinement fusion applications because lithium ions can be accelerated at high voltage in a single charge state (Li/sup +/) with a high mass-to-charge ratio and appropriate range for efficient focusing and heating of a hohlraum ICF target. Scaling to ion power densities adequate to drive high gain pellet implosions (600 TW at 30 MeV) will require a large number of beams transported, temporally bunched, and focused onto a target, with the necessary target standoff to ensure survival of the driver modules. For efficient long distance transport and focusing to a small pellet, lithium beam divergence must be reduced to about 12 mrad or less (depending on the transport scheme). To support the eventual development of a light ion driver module for ICF applications, we are currently working to improve the composition, uniformity, and divergence of lithium ion beams produced by both passive LiF and active laser-generated lithium ion sources on extraction applied-B ion diodes on the SABRE accelerator (1 TW, 5 MV, 250 kA). We will report on the operation of this lithium beam divergence diagnostic and on results of time-resolved divergence measurements in progress for passive LiF ion sources and laser-produced active lithium sources operated in diode configurations designed to control divergence growth. Comparisons will also be made with time-integrated divergence results obtained with small entrance aperture ultracompact pinhole cameras.