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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 1,405 records · Page 78
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

(U) Pre-shot Report: Complex Loading of CeO 2 Powder

A cylindrically converging shock compaction experiment is designed utilizing the Precision High Energy-density Liner Implosion eXperiment (PHELIX) platform to dynamically load CeO 2 powder. Parametric analyses investigating the effect of PHELIX cassette geometry, PHELIX total capacitor charge, and powder compaction model on the predicted shocked density profile of the CeO 2 powder are performed using the LANL codes FLAG and RAVEN. One PHELIX cassette geometry is designed to be used in two compaction experiments using PHELIX capacitor charges of 85 and 90 kV. Predictions of the shocked density profile in the CeO 2 powder are presented for each experimental configuration using both the Ramp and P-α compaction models. The two compaction models predict shocked density profiles in the CeO 2 powder that are significantly different and should be distinguishable using proton radiography as a diagnostic.

36 MATERIALS SCIENCE↗
DOE OSTI2018

A Tale of Three Bombs

The first three implosion bombs, Trinity, Fat Man, Gilda, and Helen (Operation Crossroads) that ushered in the nuclear era tested the limit s of 1940’s technology in diagnostics probably more so than developing the explosive devices themselves. Measuring something that is millions of times hotter than the sun, has radiation levels higher than any stellar phenomenon, and occurring in a few millionths of second was a quite formidable task. But, with the use of cameras, electronics of the day, spectrographs, geosensors, microphone, and the unsurpassed cleverness of the Manhattan scientist output of the first nuclear detonations were not only accomplished but set the standard for testing. This presentations takes a short look at some of the diagnostics, the results and failure, and how they shaped the future of atomic testing.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗
DOE OSTI2018

Developing Quantum Levitation of ICF Capsules Coated with MgB 2 Thin Films

Current inertial confinement fusion (ICF) capsule support technologies create implosion perturbations which reduce fusion yield, driving the search for new support paradigms. Quantum levitation of the capsule will eliminate the requirement of a physical support structure, increasing fusion yield. The application of an external magnetic field to a capsule coated with a superconducting film can provide the necessary conditions for levitation. Magnesium diboride (MgB 2 ) is an attractive option for ICF applications as it has a high reported superconducting transition temperature of 39 K and is a low Z compound. This project is part of an ongoing effort which seeks to coat ICF capsules with a thin layer of superconducting MgB 2 . This project studied the synthesis of MgB 2 and diffusion/reaction kinetics of B/Mg/B m ultilayer thin films. These films were sputter deposited on flat glassy carbon substrates. Films were annealed in a tube furnace at temperatures between 400 °C and 650 °C for a total of 29 hours with film characterization done at predetermined intervals. At each interval, superconducting properties of the samples were evaluated with superconducting quantum interference device (SQUID) magnetometry, while Rutherford backscattering (RBS) with 2 MeV 4 He + ions was done to determine the composition and depth profile of the films. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to characterize surface morphology. Superconducting behavior was observed in thin films annealed at and above 450 °C. Formation of superconducting MgB 2 at 450 °C h as not been previously reported below 500 °C. The surface of the samples annealed at 500 °C and below was smooth with a measured roughness of ~3 nm. After 29 hours of annealing time, the 450 °C sample had a transition temperature of 27.3 K. The highest transition temperature measured was 30.9 K and was associated with a sample annealed for 29 hours at 650 °C. Transition temperatures were weakly positively correlated with annealing temperature and showed dependence on initial structural quality and oxygen contamination. Current research is attempting to synthesize superconducting MgB 2 coatings on spherical Si beads with the findings of this study. Future efforts are focused on the construction and testing of a levitation apparatus.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Top Ten Weapons Breakthrough in Los Alamos' History

The dawn of the Nuclear Age occurred on the morning of July 16,1945, when Los Alamos conducted the Trinity test. Scientists and engineers from the U.S., Britain, and Canada proved the feasibility of weaponizing energy from plutonium nuclear fission using an implosion mechanism.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗
DOE OSTI2018

Dynamics of X-pinches Powered by a Capacitor Bank

X-pinches are formed by crossing two metal wires in the shape of the letter ‘X’ between the electrodes of a pulsed power device. The plasma generated then evolves in complex ways and has been the subject of many experiments and simulations, both as a plasma object and for its use as a source of intense soft x-rays, of interest to high energy density plasma (HEDP) studies. The dynamics of the x-pinch that lead to the emission x-ray photons begin soon after this initial explosive phase, resulting in the formation of a micro z-pinch (≤ 300 µm long, ~100 µm diameter) at the crossing point. If the current is high enough, then a subsonic plasma implosion in the micro z-pinch begins, which creates a high density, high temperature plasma. These x-pinches have been typically studied at the nanosecond time scale (rise-time $τ_r ≤ 100 ns, dI/dt > 1 kA/ns$). The microsecond x-pinch ($I_p~350 kA, τ_{1/4} = 1 µs, 0.3 kA/ns$) allows a different parameter space to be studied that compliments HEDP studies in the nanosecond regime (with an attendant lower hard-radiation hazard) but it also creates plasma conditions that are interesting in their own right, with features that make it a good model for studying the hydrodynamics of astrophysical jets, for example. With high electron density and temperatures pushing close to 0.5 keV, it is relevant for high energy density studies and provides a suitable test bed for the spectroscopy of highly ionized atoms. The aim of the original proposal was to initiate a new experimental plasma research program at Florida A&M University with three main objectives: (1) To create x-pinch plasmas from different materials using a direct capacitor bank discharge and to study the dynamics of the high-density plasmas and their associated soft x-ray emission properties and potential applications. (2) Understanding the nature of the supersonic plasma jets observed in the mid-plane of the microsecond x-pinch and their relevance as a laboratory model for studying astrophysical jets. (3) To provide a research platform to support the education of under-represented undergraduate and graduate students at Florida A&M University and to provide training in high energy density laboratory plasma physics. Each of the main objectives has been met and results of the work have been published in refereed journals or presented at several scientific meetings. A number of students both undergraduate and graduate have participated in the research program in a hands-on way and have thereby acquired training in high energy density physics. The success of the work can also be measured in two PhD dissertations (one of which is still in progress). The acquisition of important research equipment and instrumentation means that the work can continue in some fashion.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2018

Scorpius is being poised to make a sting in stockpile stewardship

Los Alamos is leading a federally directed charge to develop a new facility at the Nevada National Security Site. To study what happens to plutonium during the final stages of a nuclear weapon implosion, the plan calls for Scorpius, which will provide a radiographic capability in a lab 1,000 feet underground.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗
DOE OSTI2019

Exploring New Frontiers in Kinetic Physics in Inertial Confinement Fusion

The original objective of this Truman LDRD project was to explore the use of novel wave-particle plasma interactions in inertial confinement fusion (ICF) research. However, the emergence of many exciting developments in the national ICF program, including the Sandia- led "MagLIF" effort, led to extensive reformulation of the LDRD objectives. In the spirit of the original proposal, the research purview was broadened to encompass all "kinetic" (i.e., non-hydrodynamic) phenomena relevant to ICF. Significant research accomplishments include: developing theory and modeling strategies describing nonlocal ion losses and fusion reactivity reduction in unique burning plasma assemblies, including magnetized and spatially-deformed plasmas; developing numerical and conceptual tools describing the relationship between fuel magnetization and nuclear reaction histories in magneto-inertial fusion and applying these tools to groundbreaking MagLIF experiments on Sandia's Z Facility; and developing detailed analytic theories of the stability of imploding targets and applying them to uncover increasingly stable platforms for magnetically-driven implosions.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2019

Implicit, manifold-preserving numerical representations and solvers for multiscale kinetic simulations of plasmas

Presentation Conclusions: We have derived manifold-preserving algorithms for kinetic plasma simulation; Collisionless (PIC): we have solved the 40-year-old algorithmic challenge of developing accurate implicit PIC algorithms; Collisional (VFP): we have demonstrated a truly multiscale algorithm that has enabled routine simulation of ICF spherical capsule implosions with a few hundred cores for a couple of days.; In both cases: Strict conservation properties have been shown to be critical for long-term accuracy.; Significant algorithmic acceleration has been achieved by using nested asymptotic models.; We have seen similar benefits in other applications

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2016

DPF Test Conditions: FY 2016

A Neutron Diagnosed Subcritical Experiment (NDSE) is designed to quantitatively measure the reactivity of a subcritical (k eff <1.0) plutonium experiment and thereby improve our understanding of primary performance in the absence of underground nuclear testing. Successful implementation of this diagnostic requires a short, intense burst of neutrons be delivered to the fissile assembly at a precise time during a plutonium implosion. Monte Carlo particle transport simulations of representative subcritical experiments have been performed to establish the pulse shape, flux, and timing requirements for the NDSE neutron source. Additional requirements have also been established for detector sensitivity, acceptable background levels, and total diagnostic reliability.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2019

Preliminary Design Studies for a Hydro-Growth Radiography Platform to Study the Double Shell Ablator Joint

Double shell target assembly requires mating two hemispheres of aluminum to form the ablator, and the design of the mating joint governs the dimensions of the gap that remains following ablator assembly. Radiographic data from double shell implosions with two different joint designs demonstrate the importance of having a smaller outer gap to minimize perturbation growth, but higher quality data is desirable for validating simulations of such localized engineering features. A double shell hydrogrowth radiography platform is proposed to enable detailed measurements of the joint feature evolution for comparison to simulation predictions. The conservative design is based on a successfully fielded double shell keyhole target, but the tungsten inner shell is replaced with molybdenum to allow imaging with X-rays from a zirconium backlighter (16.3 keV). Eulerian radiation-hydrodynamics simulations with adaptive mesh refinement are used to predict joint feature evolution for several different joint designs. Synthetic radiographs produced from ablator-only calculations demonstrate that the evolution of different joint morphologies can be radiographed and distinguished. Feedthrough of the joint perturbation to a molybdenum inner shell is predicted to be measurable at a convergence ratio of 2.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Modeling of Nonlocal Electron Conduction for Inertial Confinement Fusion

In this report Chenhall presents a new Monte Carlo (MC) transport method developed as part of his PhD thesis work funded via fellowship by Sandia National Laboratories. The model is used to simulate the electron thermal transport within inertial confinement fusion (ICF) type problems. The new model aims to improve upon the currently used implicit Schurtz, Nicolai, and Busquet (iSNB) method, in particular by using finite particle ranges in comparison to the exponential solution of a diffusion method and by improved higher order angular modeling. The new method is being developed using the 1D LILAC and 2D DRACO codes developed by the Rochester Laboratory for Laser Energetics. The model is compared to iSNB for several ICF type problems: Omega shot 60303 a shock timing experiment, Omega shot 68951 a cryo target implosion and a NIF phase plate polar direct drive design. Overall, the MC method performs at least as well as the iSNB method and appears to indicate a lower predicted preheat ahead of the shock fronts. However, the difference in overall results between iSNB and MC transport is small for the choice of test problems and further simulations will need to be run to fully understand the difference between the models.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2016

Auto-magnetizing (AutoMag) liners for MagLIF: Helically-wound composite liners.

Magnetized Liner Inertial Fusion (MagLIF) is an inertial confinement fusion (ICF) concept that includes a strong magnetic field embedded in the fuel to mitigate thermal conduction loss during the implosion. MagLIF experiments on Sandia's 20 MA Z Machine uses an external Helmholtz-like coil pair for fuel premagnetization. By contrast, the novel AutoMag concept employs a composite liner (cylindrical tube) with helically oriented conduction paths separated by insulating material to provide axial premagnetization of the fuel. Initially, during a current prepulse that slowly rises to %7E1 MA, current flows helically through the AutoMag liner, and sources the fuel with an axial field. Next, a rapidly rising main current pulse breaks down the insulation and current in the liner becomes purely axial. The liner and premagnetized fuel are then compressed by the rapidly growing azimuthal field external to the liner. This integrated axial-field-production mechanism offers a few potential advantages when compared to the external premagnetization coils. AutoMag can increase drive current to MagLIF experiments by enabling a lower inductance transmission line, provide higher premagnetization field (>30 T), and greatly increase radial x-ray diagnostic access. 3D electromagnetic simulations using ANSYS Maxwell have been completed in order to explore the current distributions within the helical conduction paths, the inter - wire dielectric strength properties, and the thermal properties of the helical conduction paths during premagnetization (%7E1 MA in 100ns). Three liner designs, of varying peak field strength, and associated varying risk of dielectric breakdown, will soon be tested in experiments on the %7E 1 MA, 100ns Mykonos facility. Experiments will measure B z (t) inside of the line r and assess failure mechanisms.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2016

Investigating Laser Preheat and Applied Magnetic Fields Relevant to the MagLIF Fusion Scheme

The MAGnetized Liner Inertial Fusion (MagLIF) scheme has achieved thermonuclear fusion yields on the Z Facility by imploding a cylindrical liner filled with D 2 fuel that is preheated with a multi-kJ laser and pre-magnetized with an axial Bz=10 T magnetic field. Preheating (T e = 100-200 eV) and pre-magnetizing (10-30 T) the fuel serves to reduce the implosion velocity required to achieve multi-keV fusion-relevant temperatures at stagnation with a modest radial convergence. The challenge of fuel preheat in MagLIF is to deposit multiple-kJ of energy into the underdense (n e /n c <0.1) fuel over ~10 mm target length efficiently and without introducing contaminants. Once the fuel is heated the applied axial magnetic field (ω ce τ e ~ 10) needs to suppress electron thermal conduction sufficiently to prevent unacceptable heat losses to the liner walls. In this LDRD we investigated laser energy deposition at two facilities: The OMEGA-EP laser at the Laboratory for Laser Energetics and the Z-beamlet laser at Sandia National Labs utilizing the PECOS chamber. Multiple experiments were carried out investigating laser transmission through LEH foils, laser heating of underdense gasses and the effects of magnetization on laser preheat. The studies find that magneto-hydrodynamic simulations are able to reproduce energy deposition at MagLIF-like conditions but that at the intensities currently used to preheat MagLIF significant laser plasma instabilities (LPI) occur which partly explain the inability of codes to reproduce previous MagLIF preheat studies. The experiments find that reducing the intensity and smoothing the beam dramatically reduces the amount of stimulated Brillouin backscatter and produces deposition profiles more similar to those produced in simulations. The experiments have provided a large and varied dataset that can be compared to simulations. As part of the LDRD new experimental capabilities have also been developed that will be used to design future MagLIF integrated experiments and investigate fuel magnetization.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2019

Benchmarking 3D-MHD simulations of electrothermal instability growth by studying z-pinches with engineered defects

The electrothermal instability (ETI) is driven by Joule heating and arises from the dependence of resistivity on temperature. ETI may drive azimuthally correlated surface density variations which seed magneto Rayleigh-Taylor (MRT) instability growth. Liner implosion studies suggest that dielectric surface coatings reduce the amplitude of ETI driven perturbations. Furthermore, previous fundamental physics studies suggest that non-metallic inclusions within the metal can seed ETI growth. In this project, we aimed to (1) determine how dielectric coatings modify ETI growth by varying the coating thickness and the surface structure of the underlying metal, and (2) study overheating from engineered defects—designed lattices of micron-scale pits. Engineered pits divert current density and drive local overheating in a way that can be compared with 3DMHD simulations. All experiments were executed on the Sandia Mykonos Facility. Facility and diagnostic investments enabled high quality data to be gathered in support of project deliverables.

42 ENGINEERING↗
DOE OSTI2020

The Road to Trinity: Seventy-five years ago, Los Alamos scientists detonated the world’s first nuclear explosion

With a brilliant hot flash and a loud boom, the giant mushroom cloud with its fiery core filled the predawn sky above the New Mexico desert. The nuclear age had begun. It was 75 years ago on July 16, 1945, that Los Alamos scientists changed the world with the successful detonation of “the Gadget” – the device created to test the Fat Man implosion-type plutonium weapon before it was taken into combat. However, the road to Trinity, as the test was named by J. Robert Oppenheimer, who is thought to have been inspired by a line in a John Donne poem, was a difficult one.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗
DOE OSTI2020

Visit Lab’s new Trinity website for videos, posters, stories and more

History was made 75 years ago today. In the early morning hours, Los Alamos scientists, engineers, and staff successfully detonated the Gadget – a plutonium, implosion-type nuclear weapon – in the New Mexico desert during the Trinity Test on July 16, 1945. Weeks later, World War II ended and, today, Trinity’s scientific legacy endures. Watch, read and learn how Los Alamos changed the world. Visit the Lab’s new website int.lanl.gov/trinity.

99 GENERAL AND MISCELLANEOUS↗
DOE OSTI2020

(U) PRAD0697 & PRAD0698: Complex Loading of CeO₂ Powder

Cerium(IV) oxide (CeO₂) powder is shock compressed using the Precision High Energy-density Liner Implosion eXperiment (PHELIX) platform. Experimental results are compared against several modeling approaches. Compaction behavior is best captured with a P-∝ model, which calculates CeO₂ powder bulk densities within 80-99% of experimental values but overpredicts densi cation at the cylindrical target's outer radius and center by up to 20%. Preliminary calculations suggest that accuracy could be increased with the inclusion of a coupled strength model. Several common computational modeling approaches for the shock compression response of granular materials and the magnetohydrodynamic (MHD) force upon the impactor/liner in pulsed power compression experiments are investigated and analyzed for their validity. The Bi-linear Ramp, P-∝ PACXP, and P-∝ Menikoff-Kober continuum compaction models are calibrated to planar impact Hugoniot data for CeO₂ powder and used to predict the powder's shock compaction response under non-planar shock wave compression. MHD calculations of the PHELIX pulsed power driver are performed using an idealized resistor-inductor-capacitor (RLC) circuit calibrated to previous experiments. All simulations are performed using the LANL code FLAG. Two validation experiments are computationally designed using the calibrated compaction and circuit models, executed using the PHELIX platform on CeO₂ targets with initial porous densities of 3.95 and 4.03 g/cm³, measured with proton radiography, and analyzed against the model predictions. The two P-∝ models more accurately describe CeO₂ powder densi cation than the Bi-linear Ramp model. However, the two P-∝ models overpredict bulk density of the shock compressed CeO₂ powder by up to 20% when the appropriate impact velocities are applied. MHD calculations for both validation experiments underpredict liner impact velocities by 4-11% when using the idealized RLC circuit model calibrated to previous experiments. Compensating underpredictions of impact velocity and overpredictions of powder densication lead to a false accuracy in pre-shot calculations compared to experimental data. To improve correlation between simulations and experiments, the following improvements are suggested: 1. A coupled strength model for CeO₂ powder that updates strength as a function of porosity and applied stress. 2. An improved MHD circuit model that more accurately captures the PHELIX machine.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Foams in Hohlraums

Foam materials are starting to find application in laser-heated hohlraums used to drive inertial confinement fusion (ICF) implosions. The disparate scales of the solid foam elements (nm) compared to the typical problem scale (mm) make it expensive to resolve the individual foam elements in hydrodynamic calculations. In this project we developed two new models for treating foam materials – a 3D hydrodynamic model that treats the foam as bits of pre-expanded solid material separated by voids, and a subgrid model that captures the essential physics of laser-heated foams without requiring resolution of the individual solid elements. We also explored the microphysics of the transition from interpenetrating kinetic behavior to fully-collisional fluid-like behavior during the early time heating and expansion of foam elements through a combination of single-fluid and multi-fluid hydrodynamics calculations and particle-in-cell calculations. The model was benchmarked against these calculations and against experimental data on laser-heated chemical and additive-manufactured (AM) foams. Since there was no existing data on laser-heated AM foams, we performed the first experiments on such foams at the Jupiter Laser Facility. Samples of three different types of printed AM foams were heated using a single 0.5 micron laser. The foam densities ranged from 10 to 100 mg/cc (supercritical for 0.5 micron light). We measured the backscattered light (power and spectrum), the transmitted light, and the time-integrated temperature of the foam samples. This benchmarked subgrid foam model is a new capability that should allow routine calculation of ICF designs using foam elements, potentially opening up a new design space.

36 MATERIALS SCIENCE↗