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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Benchmarking Uranyl Peroxide Capsule Chemistry in Organic Media

Uranyl peroxide capsules are a recent addition to polyoxometalate (POM) chemistry. Ten years of development has ensued only in water, while transition metal POMs are commonly exploited in aqueous and organic media, controlled by counterions or ligation to render the clusters hydrophilic or hydrophobic. Here, new uranyl POM behavior is recognized in organic media, including (1) stabilization and immobilization of encapsulated hydrophilic countercations, identified by Li nuclear magnetic resonance (NMR) spectroscopy, (2) formation of new cluster species upon phase transfer, (3) extraction of uranyl clusters from different starting materials including simulated spent nuclear fuel, (4) selective phase transfer of one cluster type from a mixture, and (5) phase transfer of clusters from both acidic and alkaline media. The capsule morphology of the uranyl POMs renders accurate characterization by X‐ray scattering, including the distinction of geometrically similar clusters. Compositional analysis of the aqueous phase post‐extraction provided a quantitative determination of the ion exchange process that enables transfer of the clusters into the organic phase. Preferential partitioning of uranyl POMs into organic media presents new frontiers in metal ion behavior and chemical reactions in the confined space of the cluster capsules in hydrophobic media, as well as the reactivity of clusters at the organic/aqueous interface.

Neal, Harrison A.↗
DOE OSTI2016

First beryllium capsule implosions on the National Ignition Facility

The first indirect drive implosion experiments using Beryllium (Be) capsules at the National Ignition Facility confirm the superior ablation properties and elucidate possible Be-ablator issues such as hohlraum filling by ablator material. Since the 1990s, Be has been the preferred Inertial Confinement Fusion (ICF) ablator because of its higher mass ablation rate compared to that of carbon-based ablators. This enables ICF target designs with higher implosion velocities at lower radiation temperatures and improved hydrodynamic stability through greater ablative stabilization. Recent experiments to demonstrate the viability of Be ablator target designs measured the backscattered laser energy, capsule implosion velocity, core implosion shape from self-emission, and in-flight capsule shape from backlit imaging. The laser backscatter is similar to that from comparable plastic (CH) targets under the same hohlraum conditions. Implosion velocity measurements from backlit streaked radiography show that laser energy coupling to the hohlraum wall is comparable to plastic ablators. The measured implosion shape indicates no significant reduction of laser energy from the inner laser cone beams reaching the hohlraum wall as compared with plastic and high-density carbon ablators. These results indicate that the high mass ablation rate for beryllium capsules does not significantly alter hohlraum energetics. In addition, these data, together with data for low fill-density hohlraum performance, indicate that laser power multipliers, required to reconcile simulations with experimental observations, are likely due to our limited understanding of the hohlraum rather than the capsule physics since similar multipliers are needed for both Be and CH capsules as seen in experiments.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2016

Mitigating the impact of hohlraum asymmetries in National Ignition Facility implosions using capsule shims

Here, current indirect drive implosion experiments on the National Ignition Facility (NIF) are believed to be strongly impacted by long wavelength perturbations driven by asymmetries in the hohlraum x-ray flux. To address this perturbation source, active efforts are underway to develop modified hohlraum designs with reduced asymmetry imprint. An alternative strategy, however, is to modify the capsule design to be more resilient to a given amount of hohlraum asymmetry. In particular, the capsule may be deliberately misshaped, or “shimmed,” so as to counteract the expected asymmetries from the hohlraum. Here, the efficacy of capsule shimming to correct the asymmetries in two recent NIF implosion experiments is assessed using two-dimensional radiation hydrodynamics simulations. Despite the highly time-dependent character of the asymmetries and the high convergence ratios of these implosions, simulations suggest that shims could be highly effective at counteracting current asymmetries and result in factors of a few enhancements in neutron yields. For higher compression designs, the yield improvement could be even greater.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2018

Novel Capsule Fill Tube Assemblies for the Hydrodynamic Growth Radiography Targets

Capsule Fill Tube Assemblies (CFTAs) consist of an ablator capsule and fill tube via a laser drilled funnel hole. This hole then tapers from 17 μm diameter at the outer surface of the ablator capsule to less than 5 μm diameter on the inside of the capsule over approximately 200 μm of wall thickness. Demand for better understanding of the fill tube perturbation during the capsule implosion has driven advancements in the fill tube design. Engineering efforts have been made on Hydrodynamic Growth Radiography Assemblies (HGRs) using multiple tube design variations, including alternative angles, depths, sizes, and location with engineered defects to showcase fill tube effects during an implosion. Furthermore, testing has shown that these CFTAs and HGRs have survived all fabrication and transport to from General Atomics to Lawrence Livermore National Laboratory. These assemblies have also passed cryogenic testing at General Atomics. An overview of alternative CFTA designs, fabrication methods and developments will be presented.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2018

Beryllium capsule implosions at a case-to-capsule ratio of 3.7 on the National Ignition Facility

Beryllium is a candidate ablator material for indirect-drive inertial confinement fusion experiments, motivated by its high mass ablation rate, which is advantageous for implosion coupling efficiency and stabilization of the ablation-front instability growth. In this paper, we present new data on the shock propagation, in-flight shape, and hot spot self-emission shape from gas-filled capsules that demonstrate the feasibility of predictable, symmetric, controllable beryllium implosions at a case-to-capsule ratio of 3.7. The implosions are round (Legendre mode 2 amplitude ≲5%) at an inner beam power and the energy fraction of 26%–28% of the total, indicating that larger beryllium capsules could be driven symmetrically using the National Ignition Facility.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2018

Neutronic Comparison of New HSA Cobalt Capsule Design to Legacy HSA Cobalt Capsule Design

A comparison of the neutronic properties between the legacy high specific activity (HSA) cobalt capsule design and the new HSA cobalt capsule design was conducted utilizing the full advanced test reactor core MCNP model. The neutron flux and effective neutron absorption cross section for the desired (n,gamma) reaction as well as the undesired reactions (n,2n), (n, alpha), and (n,p) for the cobalt target material for each design was calculated and compared. It was found that the effective neutron absorption cross section for the desired reaction (n,gamma) on the target material that directly produces Co-60 is slightly higher in the new design than the legacy design, and there is little statistical difference between the two target designs for the undesired reactions (n,2n), (n, ), and (n,p). Based on these results, neutronically, there does not appear to be a significant difference between the two capsule designs.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2017

Toward highly efficient electrocatalyst for Li–O 2 batteries using biphasic N-doping cobalt@graphene multiple-capsule heterostructures

To promote lithium-oxygen batteries available for practical applications, the development of advanced cathode catalysts with low-cost, high activity and stable structural properties is demanded. Such development is rooted on certain intelligent catalyst-electrode design that fundamentally facilitates electronic and ionic transport, and improves oxygen diffusivity in a porous environment. Here we design a biphasic nitrogen-doped cobalt@graphene multiple-capsule heterostructure, combined with a flexible, stable porous electrode architecture, and apply it as promising cathodes for lithium-oxygen cells. The biphasic nitrogen-doping feature improves the electric conductivity and catalytic activity; the multiple-nanocapsule configuration makes high/uniform electro-active zones possible; furthermore, the colander-like porous electrode facilitates the oxygen diffusion, catalytic reaction, and stable deposition of discharge products. Finally, the electrode exhibits much improved electrocatalytic properties associated with unique morphologies of electrochemically grown lithium peroxides.

25 ENERGY STORAGE↗
DOE OSTI2017

Capsule implosions for continuum x-ray backlighting of opacity samples at the National Ignition Facility

Direct drive implosions of plastic capsules have been performed at the National Ignition Facility to provide a broad-spectrum (500–2000 eV) X-ray continuum source for X-ray transmission spectroscopy. The source was developed for the high-temperature plasma opacity experimental platform. Initial experiments using 2.0 mm diameter polyalpha-methyl styrene capsules with ~20 μm thickness have been performed. X-ray yields of up to ~1 kJ/sr have been measured using the Dante multichannel diode array. The backlighter source size was measured to be ~100 μm FWHM, with ~350 ps pulse duration during the peak emission stage. Lastly, these results are used to simulate transmission spectra for a hypothetical iron opacity sample at 150 eV, enabling the derivation of photometrics requirements for future opacity experiments.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1970

20th Century NASA History: Mercury Manned Orbital Capsule Detail Specification and Project Mercury Capsule Flight Operations Manual

The detailed preparation required in attempting a mission of the magnitude and scope of PROJECT MERCURY obviously cannot and need not be covered in a document of the handbook type. Prior to any actual attempt to launch a manned capsule, many weeks will be spent in an extensive training and familiarization program. The information contained in this manual, therefore, will pre-suppose a detailed knowledge of the capsule systems and will be confined, for the most part, to procedural data.

Source record↗
DOE OSTI2016

Development of a krypton-doped gas symmetry capsule platform for x-ray spectroscopy of implosion cores on the NIF

The electron temperature at stagnation of an ICF implosion can be measured from the emission spectrum of high-energy x-rays that pass through the cold material surrounding the hot stagnating core. Here we describe a platform developed on the National Ignition Facility where trace levels of a mid-Z dopant (krypton) are added to the fuel gas of a symcap (symmetry surrogate) implosion to allow for the use of x-ray spectroscopy of the krypton line emission.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗