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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 145 records · Page 8

High Energy Density Physics of Inertial Confinement Fusion Ablator Materials (Final Technical Report)

The goal of this project was to conduct dynamic compression experiments and predictive simulations to reveal the fundamental high-energy-density (HED) physics of amorphous carbon. These results are essential for assessing amorphous carbon as a potential ablator material for next generation of inertial confinement fusion (ICF) capsules. We made significant progress in exploring the HED properties of amorphous carbon through experiments at Omega EP Laser and the European XFEL, in addition to billion-atom, quantum-accurate molecular dynamics (MD) simulations. Through our joint experimental and simulation program, we mapped the phase diagram of amorphous carbon, uncovering its range of metastability and identifying phase transitions to diamond and liquid carbon along the Hugoniot and at higher pressures using double shock compression pathways. Our findings indicate that amorphous carbon melts at significantly lower shock pressures than high-density carbon (diamond). However, nanocrystalline diamond nucleates across a broad range of pressures and temperatures. This emergence of the nanocrystalline microstructure during compression can negatively impact the planarity of the shock front and potentially trigger ablator/fuel mixing during Inertial Fusion Energy (IFE) applications.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

Advancing sustainable aviation fuel with high-energy-density bicycloalkanes production from corn stover mixed sugars

Bicycloalkanes stand out as a replacement for aromatics from conventional jet fuel (CJF) because of their high energy density and lower freezing point. Most reports to date have focused on synthesizing bicycloalkanes using model compounds or single sugar components of lignocellulose. Here, we utilize all lignocellulosic sugars of corn stover (CS) to produce bicycloalkanes. First, furfural (FFR) and 5-hydroxymethyl furfural (5-HMF) are produced via acid-catalyzed dehydration, achieving combined FFRs molar yields ranging from 65% to 73%, respectively. The resulting FFRs are converted to cyclopentanones with molar yields within the range of 57%–63% via hydrogenation and Piancatelli rearrangement. Further aldol condensation of cyclopentanones yields C 10 -C 12 oxygenates with 80 mol %. Lastly, these oxygenates are directly hydrodeoxygenated to bicycloalkanes in a yield of 83.8 mol %. The resulting bicycloalkanes exhibit tier α fuel properties consistent with Jet A fuel (CJF) specifications and blend compatibility with CJF at a 37% volumetric ratio.

09 BIOMASS FUELS↗

Simulation and flow physics of a shocked and reshocked high-energy-density mixing layer

This work describes a computational investigation of multimode instability growth and multimaterial mixing induced by multiple shock waves in a high-energy-density (HED) environment, where pressures exceed 1 Mbar. The simulations are based on a series of experiments performed at the National Ignition Facility (NIF) and designed as an HED analogue of non-HED shock-tube studies of the Richtmyer–Meshkov instability and turbulent mixing. A three-dimensional computational modelling framework is presented. It treats many complications absent from canonical non-HED shock-tube flows, including distinct ion and free-electron internal energies, non-ideal equations of state, radiation transport and plasma-state mass diffusivities, viscosities and thermal conductivities. The simulations are tuned to the available NIF data, and traditional statistical quantities of turbulence are analysed. Integrated measures of turbulent kinetic energy and enstrophy both increase by over an order of magnitude due to reshock. Large contributions to enstrophy production during reshock are seen from both the baroclinic source and enstrophy–dilatation terms, highlighting the significance of fluid compressibility in the HED regime. Dimensional analysis reveals that Reynolds numbers and diffusive Péclet numbers in the HED flow are similar to those in a canonical non-HED analogue, but conductive Péclet numbers are much smaller in the HED flow due to efficient thermal conduction by free electrons. It is shown that the mechanism of electron thermal conduction significantly softens local spanwise gradients of both temperature and density, which causes a minor but non-negligible decrease in enstrophy production and small-scale mixing relative to a flow without this mechanism.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

Characterizing x-ray transmission through filters used in high energy density physics diagnostics

We report on the design and implementation of a new system used to characterize the energy-dependent x-ray transmission curve, Θ(E), through filters used in high-energy density physics diagnostics. Using an Amptek X-123-CdTe x-ray spectrometer together with a partially depleted silicon surface barrier detector, both the energy spectrum and total emission of an x-ray source have been accurately measured. By coupling these detectors with a custom PROTO-XRD x-ray source with interchangeable cathodes, accurate characterizations of Θ(E) for filters of varying materials and thicknesses have been obtained. The validity of the technique has been confirmed by accurately reproducing areal densities for high-purity filters with known x-ray transmission properties. In this paper, the experimental setup is described and the results of absorption calibrations performed on a variety of different filters are presented.

47 OTHER INSTRUMENTATION↗

Exploring high-intensity laser-driven secondary sources via high-order spectral pulse shaping for high-energy-density experiments

We present here the results of an investigation that aims to explore the impact of spectral pulse shaping on the generation of high-energy electrons (>1 MeV) and x rays (∼5–9 keV) using a high-intensity (I∼10 21 W/cm 2 ) laser system. The study involved a systematic scan of a broad parameter space in group delay dispersion and third-order dispersion, with variations up to 4 × 10 3 fs −2 and 6 × 10 4 fs −3 , respectively, to identify optimal conditions for enhancing secondary source yields. Several spectral phase conditions were found to significantly enhance the generation of hot electrons and x rays by amounts reaching up to 50% relative to the transform-limited pulse. The experiment, conducted at the Scarlet laser facility (800 nm, 5 J, 30 fs) at the Ohio State University, highlights the potential of spectral pulse shaping as a powerful tool for tuning secondary laser-driven sources. These findings are particularly relevant for advancing brighter x-ray and electron probes for high-energy-density science.

Physics - Plasma physics↗

Generation and Control of Self-Organized Nonlinear Kinetic Structures in High Energy Density Plasmas in the Presence of Intense Magnetic Fields and Ultrashort Laser Pulses

Goals were to study the interplay between electron plasma waves (EPW), KEEN waves and externally generated magnetic fields. In particular, the Weibel instability B field generation process and its interrelationship with the existence of nonlinear EPWs in high energy density plasmas. We focused on a number of models of how Kinetic, Nonlinear Electron Plasma Waves, KNL-EPW and KEEN waves create anisotropic electron velocity distribution functions, e- VDF, and how these anisotropic e- VDFs in turn drive the Weibel instability and generate B fields. Our goal is to control the SRS and SKEENS processes that generate the KNL-EPW, control the anisotropy, and thus also control the dynamics of the resulting B fields, their influence on the transport coefficients and heat transport that results, their modification of SRS itself and the reinforced anisotropy driven loop gain.

(Kinetic electrostatic electron nonlinear) KEEN wa↗

Unlocking multiphysics design guidelines on Si/C composite nanostructures for high-energy-density and robust lithium-ion battery anode

In general, current material fabrication guidance for novel designs of Si/C composite particle materials focuses on electrochemical behavior and redox reactions at the nano/micro level. However, such guidance cannot provide detailed information for predicting mechanical deformations of the composite particles, especially when the mechanical field coupled with electrochemical and thermal fields. Here, we establish an electro-chemo-mechanical model and implement it to quantitatively analyze the multiphysics behavior of five representative Si/C composite nanostructures. Modeling and computation discover that yolk-shell and dual-shell structures are more robust in terms of particle fractures. When considering electrochemical performance, the yolk-shell structure is the best among the compared five Si/C composites. Finally, we map design guidance to further illustrate quantitative structure-property relationships. This study provides novel insights on Si/C composite nanostructure anode material design and additional powerful design tools for next-generation high-energy-density lithium-ion batteries.

25 ENERGY STORAGE↗

Magnetic Reconnection in High Energy Density Laboratory Plasmas

Understanding the physics of collisionless, magnetized plasmas is key to unlocking a number of important problems in space and astrophysics. Magnetic reconnection is a fundamental mechanism which can explosively release stored magnetic energy, convert it to plasma heat and flows, and accelerate particles. In this project we developed technique and conducted experiments and simulations of magnetic reconnection in laser produces plasmas. Through this project, we also developed experimental techniques to generate magnetized collisionless shocks, and we therefore expanded the scope of the project to develop these experiments. These projects make fundamental progress on understanding the dynamics of magnetized laser-produced plasmas. In additional to plasma astrophysics, these results have broad interest for laboratory high energy density plasmas, since magnetic fields can be used to confine and control plasmas in many contexts and may offer new capabilities toward laboratory ignited plasmas.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

Developing Materials for High-Energy-Density Solid State Li-S Batteries

Solid-state lithium-sulfur batteries are considered to be the next-generation power source for vehicle applications due to their high energy density (up to 3 times more than current Li-ion) and low cost of sulfur (100 times less than conventional cobalt oxide). However, issues with solid-state electrolyte stability, conduction pathways in the sulfur cathode, and the interface between solid-state electrolyte and sulfur cathode must be solved in order to allow commercialization. This project demonstrates the creation of new, advanced materials which overcome these inherent issues. Current approaches based on polymer or liquid electrolyte with additives have been able to improve stability at the cost of efficiency. In contrast, by creating new hybrid materials it is possible to achieve both stability and efficiency. We developed a novel sulfide-based solid electrolyte, a sulfur-carbon composite cathode, and explored various additives to stabilize the interface of solid electrolyte and cathode. After the desired properties were achieved, these materials were integrated into a high-performance solid-state battery, bringing low-cost high-energy solid-state lithium-sulfur batteries one step closer to reality.

25 ENERGY STORAGE↗

Study of x-ray fluorescence spectroscopy from high-energy-density plasmas (Final Report)

The primary objective of this subcontract was to support the development of x-ray fluorescence spectroscopy (XFS) as a diagnostic tool for high-energy-density (HED) plasmas. Several experimental campaigns were completed to develop and benchmark XFS at various plasmas conditions of interest for inertial confinement fusion and HED science. The experimental measurements at the Omega laser facility used x-ray absorption spectroscopy (XAS) to determine the plasma temperature from the shape of the K-edge to benchmark XFS data. During the course of these experiments, it was found that XAS can also constrain ionization from bound-bound absorption features, and it became a primary diagnostic in this study. Several experimental campaigns were conducted at the Omega laser facility to refine XAS and XFS measurements of warm dense copper.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

Exploring applications of laser-produced relativistic pair plasma jets for high-energy-density physics and astrophysics (LDRD Final Report)

We have successfully completed the ER project on the relativistic electron-positron “pair” plasmas which have unique physics property fundamental to High Energy Density (HED) plasma physics and laboratory astrophysics. Over the three-year span, we completed three discovery science experiments on NIF ARC, established a new NIF platform for the pair plasma experiments which also benefited a range of other science and HED experiments using ARC. Additional 5 experimental campaigns on Omega and Gekko facilities have also been executed successfully. Our results on the pair physics and pair-plasma interactions have been published in journal and conferences and highlighted on the Lab’s Newsline.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗