Reducing deuterium-tritium ice roughness by electrical heating of the saturated vapor

High gain targets for inertial confinement fusion (ICF) contain a layer of deuterium-tritium (DT) ice which surrounds a volume of DT gas in thermal equilibrium with the solid. The roughness of the cryogenic fuel layer inside of ICF targets is one of the sources of imperfections which cause implosions to deviate from perfect one dimensional performance. Experiments at Lawrence Livermore National Laboratory have shown that applying a heat flux across the inner surface of a hydrogen layer such as that inside an ICF target reduces the intrinsic roughness of the surface. We have developed a technique to generate this heat flux by applying and electric field to the DT vapor in the center of these shells. This vapor has a small but significant conductivity due to ionization caused by beta decay of tritium in the vapor and the solid. We describe here experiments using a 1.15 GHz cavity to apply an electric field to frozen DT inside of a sapphire test cell. The cell and cavity geometry allows visual observation of the frozen layers

Forming uniform HD layers in shells using infrared radiation

Generating a volumetric heat source in solid deuterium hydride, HD, allows the formation of a spherical crystalline shell of HD inside a transparent plastic shell. Pumping the infra-red (IR) collisionally induced vibration-rotation band of solid HD contained inside a transparent plastic shell generates the volumetric heat source in the HD lattice. HD layers 150 - 250 {micro}m thick formed near the triple point have a surface roughness rms between l-3 {micro}m and become rougher with decreasing temperature. Solid growth dynamics have a significant impact on the quality of the resultant layer

Lawrence Livermore Laboratory heavy ion fusion program

In the large fusion program at Livermore we are actively doing research in most areas of inertial confinement fusion. The areas in which we are funded for research specific to heavy ion fusion are: (1) target design; (2) energy conversion chamber design and (3) ion beam propagation in the combustion chamber. There are two main thrusts to the target design effort: (1) development of targets which are optimally suited to heavy ion fusion power production and (2) fundamental studies of the beam-target interaction

Forming and smoothing D{sub 2} and HD layers for ICF by infra-red heating

We describe a technique to form and smooth uniform solid D{sub 2}, HD or DT layers for inertial confinement fusion targets. Pumping the infrared (IR) collision induced vibration-rotation band generates a bulk heating of the solid. Shadowgraphs reveal that this bulk heat quickly redistributes the solid into a relatively uniform layer depending on the IR intensity profile. Measured redistribution time constants are used to determine the conversion efficiency of IR light into bulk heat. Phase shifting interferometry reveals that the surface roughness decreases with increasing IR heating

Performance Requirements of an Inertial Fusion Energy Source for Hydrogen Production

Performance of an inertial fusion system for the production of hydrogen is compared to a tandem-mirror-system hydrogen producer. Both systems use the General Atomic sulfur-iodine hydrogen-production cycle and produce no net electric power to the grid. An ICF-driven hydrogen producer will have higher system gains and lower electrical-consumption ratios than the design point for the tandem-mirror system if the inertial-fusion-energy gain eta Q > 8.8. For the ICF system to have a higher hydrogen production rate per unit fusion power than the tandem-mirror system requires that eta Q > 17. These can be achieved utilizing realistic laser and pellet performances