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Spherical ablator shells that contain a thin layer of ultralow-density polymer foam have recently attracted attention in the inertial confinement fusion (ICF) community as they can be used to bring dopants for diagnostics and nuclear physics experiments in direct contact with the deuterium-tritium (DT) fuel or to study new ignition regimes by enabling the formation of uniform liquid DT fuel layers. We developed a method to fabricate these foam-lined ablator shells using a prefabricated ablator as a mold to cast the foam liner within the shell. One crucial component of this new approach is the removal of solvent from the ablator shells without collapsing the ultralow-density porous polymer network. Here, we report on a supercritical drying approach with liquid carbon dioxide that provides critical information on how to produce thin layers of low-density polymer foams in ablator shells for ICF experiments. Diffusion experiments were used to study the time required for complete solvent exchange in 2-...

Controlled doping of inertial confinement fusion (ICF) targets is needed to enable nuclear diagnostics of implosions. Here, we demonstrate that ion implantation with a custom-designed carousel holder can be used for azimuthally uniform doping of ICF fuel capsules made from a glow discharge polymer (GDP). Particular emphasis is given to the selection of the initial wall thickness of GDP capsules as well as implantation and postimplantation annealing parameters in order to minimize capsule deformation during a postimplantation thermal treatment step. In contrast to GDP, ion-implanted high-density carbon exhibits excellent thermal stability and ~100% implantation efficiency for the entire range of ion doses studied (2 × 1014 to 1 × 1016 cm−2) and for annealing temperatures up to 700°C. Finally, we demonstrate a successful doping of planar Al targets with isotopes of Kr and Xe to doses of ~1017 cm−2.

Experiments and analysis in the 2 years since the 2015 Target Fabrication Meeting have resulted in further evolution of the requirements for high-performance layered implosions. This paper is a status update on the experimental program and supporting modeling, with emphasis on the implications for fabrication requirements. Previous work on the capsule support has continued, with various other support options being explored in experiments and modeling. Work also continues on ablator composition nonuniformities, with important new results from CH experiments on Omega, and the first three-dimensional X-ray transmission measurements of Be capsules on the National Ignition Facility. Work on hohlraums continues to include near-vacuum hohlraums and U hohlraums without a gold lining. Overall, the understanding that has been achieved, along with the progress in fabrication technology, represents good continuing progress toward the goal of fusion in the laboratory.

Experiments and analysis in the 3 years since the 2012 Target Fabrication Meeting have resulted in significant improvement in understanding of the requirements for high-performance layered implosio...

Complex and precise research targets are required for the inertial confinement fusion (ICF) experiments conducted at the National Ignition Facility. During the National Ignition Campaign (NIC) the ...

The point design of beryllium capsules includes three Cu-doped layers in a 160-μm-thick beryllium shell to achieve the desired X-ray absorption profile. The beryllium capsules were deposited on glo...

The NIF point design uses a five-layer capsule to modify the X-ray absorption in order to achieve optimized shock timing. A stepped copper dopant design defines the layer structure. The production of the capsule involves pyrolysis to remove the inner plastic mandrel. Copper atoms diffuse radially and azimuthally throughout the capsule during pyrolysis. This diffusion significantly diminishes the capsule performance during implosion. Thermal and coated oxide barrier layers employed between layers mitigate the diffusion of copper during the mandrel removal process. The copper atoms do not diffuse through this barrier during pyrolysis. A capsule fabrication method that produces a capsule with a thin oxide layer will be discussed.

Targets were fabricated at Lawrence Livermore National Laboratory and were shot on the Omega laser to study the equation of state of nanoporous copper. The targets had a planar configuration and co...

Indirectly driven double shell implosions are being investigated as a possible noncryogenic path to ignition on the National Ignition Facility. Lawrence Livermore National Laboratory has made several technological advances that have produced double shell targets that represent a significant improvement to previously fielded targets. The inner capsule is supported inside the ablator shell by SiO2 aerogel with a nominal density of 50 mg/cm3. The aerogel is cast around the inner capsule and then machined concentric to it. The seamless sphere of aerogel containing the embedded capsule is then assembled between the two halves of the ablator shell. The concentricity between the two shells has been improved to less than 1.5 μm. The ablator shell consists of two hemispherical shells that mate at a step joint that incorporates a gap with a nominal thickness of 0.1 μm. Using a new flexure-based tool holder that precisely positions the diamond cutting tool on the diamond turning machine, step discontinuities...

Diamond has a unique combination of physical properties for the inertial confinement fusion ablator application, such as appropriate optical properties, high atomic density, high yield strength, an...

The current point design for ignition targets for the National Ignition Facility has a beryllium ablator. As Be is essentially impermeable to hydrogen, conceptually the shell will be filled by bori...

Highly Charged Ion (HCI) Time-of-Flight (TOF) Secondary Ion Mass Spectrometry (SIMS) has been employed to analyze the changes in the surface composition of TATB caused by low energy electron, ultraviolet, and Gamma ray irradiation. Comparisons are made between canary yellow (not irradiated) TATB and TATB that has been “greened” by exposure to radiation. We ascribe the color change from yellow to green to a loss of oxygen. Another striking aspect of this study is the presence of a feature at m/z = 30 (NO+) for highly charged ion SIMS, which does not occur in singly charged ion TOF SIMS.

The full spectrum of occupied and unoccupied σ and π orbitals is presented for solid C60, C70, and graphite, using Cls emission and absorption spectroscopy. There are significant diffcrences between C60 and C70, and even larger changes relative to their infinite analog graphite (C∝). A comparison is made with photocmission and inverse photoemission results, along with first principles quasiparticle calculations.