0000000000323402
AUTHOR
O. Legaie
Influence of a density mismatch on TMPTMA shells nonconcentricity
Some laser target designs require low-density organic foam shells to study fusion on the French high-power laser laser mega joule. Low-density trimethylolpropane trimethacrylate foam shells composed of C, H, and O, 2 mm diameter, 100-μm wall thickness, and 250 mg cm−3 density are synthesized by a microencapsulation technique using a droplet generator. These shells have to reach a sphericity higher than 99.9% and a nonconcentricity (NC) lower than 1%. The wall thickness variation is one of the most difficult specifications to meet. An important factor in reducing this defect is the density matching between the three phases of the emulsion at polymerization temperature. The influence of a den…
Characterization of the Microshell Surface Using Holography
AbstractTo characterize the shape, the quality, and the roughness of microshells, digital holographic microscopy technology is used because it offers an appropriate ability to these studies. It captures holograms to reconstruct a double image, one for the intensity and another one for the phase. Using rotation axis, bump counting for the complete microshell surface is possible with a very high speed. Using image stitching and three-dimensional surface rebuilding software, mapping can be done in a few minutes. Each bump can then be characterized on the map by its position, diameter, and height.
Germanium Doped CHxMicroshells for LMJ Targets
AbstractAt the CEA Laser “Megajoule” facility, amorphous hydrogenated carbon (a-C:H or CHx) is the nominal ablator used to achieve inertial confinement fusion experiments. These targets are filled with a fusible mixture of deuterium-tritium in order to perform ignition.Since the achievement of ignition greatly depends on the physical properties of the shell, there must be precise control of thicknesses, doping concentration, and roughness. Experimental devices associated with suitable characterizations are described in this paper. The tolerances and yields for each specification are also presented. Some specifications are largely reached; high-frequency surface roughness due to isolated sur…