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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 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

AZD5582 plus SIV-specific antibodies reduce lymph node viral reservoirs in antiretroviral therapy-suppressed macaques

The main barrier to HIV cure is a persistent reservoir of latently infected CD4 + T cells harboring replication-competent provirus that fuels rebound viremia upon antiretroviral therapy (ART) interruption. A leading approach to target this reservoir involves agents that reactivate latent HIV proviruses followed by direct clearance of cells expressing induced viral antigens by immune effector cells and immunotherapeutics. We previously showed that AZD5582, an antagonist of inhibitor of apoptosis proteins and mimetic of the second mitochondrial-derived activator of caspases (IAPi/SMACm), induces systemic reversal of HIV/SIV latency but with no reduction in size of the viral reservoir. In this study, we investigated the effects of AZD5582 in combination with four SIV Env-specific Rhesus monoclonal antibodies (RhmAbs) ± N-803 (an IL-15 superagonist) in SIV-infected, ART-suppressed rhesus macaques. Here we confirm the efficacy of AZD5582 in inducing SIV reactivation, demonstrate enhancement of latency reversal when AZD5582 is used in combination with N-803 and show a reduction in total and replication-competent SIV-DNA in lymph-node-derived CD4 + T cells in macaques treated with AZD5582 + RhmAbs. Further exploration of this therapeutic approach may contribute to the goal of achieving an HIV cure.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2024

Sustainable layered cathode with suppressed phase transition for long-life sodium-ion batteries

Sodium-ion batteries are among the most promising alternatives to lithium-based technologies for grid and other energy storage applications due to their cost benefits and sustainable resource supply. For the cathode—the component that largely determines the energy density of a sodium-ion battery cell—one major category of materials is P2-type layered oxides. Unfortunately, at high state-of-charge, such materials tend to undergo a phase transition with a very large volume change and consequent structural degradation during long-term cycling. Here we address this issue by introducing vacancies into the transition metal layer of P2-Na$_{0.7}$Fe$_{0.1}$Mn$_{0.75\square}$$_{0.15}$O2 (‘$_{\square}$’ represents a vacancy). The transition metal vacancy serves to suppress migration of neighbouring Na ions and therefore maintain structural and thermal stability in Na-depleted states. Moreover, the specific Na-O-$_{\square}$ configuration triggers a reversible anionic redox reaction and boosts the energy density. As a result, the cathode design here enables pouch cells with energy densities of 170 Wh kg -1 and 120 Wh kg -1 that can operate for over 600 and 1,000 cycles, respectively. In conclusion, our work not only suggests a feasible strategy for cathode design but also confirms the possibility of developing a battery chemistry that features a reduced need for critical raw materials.

25 ENERGY STORAGE↗
DOE OSTI2020

Electrochemically induced iodine migration in mixed halide perovskites: suppression through chloride insertion

The role of chloride in improving the stability of mixed halide perovskites (MAPbCl x Br 0.5 (1–x) I 0.5(1–x) ) 3 is probed using spectroelectrochemistry. Here, the injection of holes into mixed halide perovskite films through applied anodic bias results in the selective migration of iodine with ultimate expulsion into the electrolyte. Increasing the Cl content (x = 0 to 0.1) in the mixed halide perovskite suppresses the iodine mobility and thus decreases the rate of its expulsion into the solution. Implications of iodine mobility induced by hole accumulation and its impact on overall stability is discussed.

14 SOLAR ENERGY↗
DOE OSTI2020

Suppression of voltage-decay in Li 2 MnO 3 cathode via reconstruction of layered-spinel coexisting phases

Voltage decay, i.e., the voltage decrease during electrochemical cycling, has been a decade-long challenge for lithium-ion batteries. This issue not only leads to a substantial loss of energy density, but also raises challenges for the battery management system, hindering the commercial application of high capacity lithium-rich oxide. Here, we show that through a combination of electrochemical conditioning and thermal treatment, Li 2 MnO 3 , the parent compound of lithium-rich oxide, which typically displays severe voltage and capacity decay, could be converted into a new phase that essentially suppresses the voltage decay with improved capacity retention and rate performance. Furthermore, by combining atomic-sensitive nuclear magnetic resonance, differential electrochemical mass spectrometry and synchrotron-based resonant inelastic X-ray scattering, we disclose that treatment triggers the formation of three-coexisting phases, i.e., the lithium-rich layered, spinel and defect spinel phases, which enables improved reversibility of the oxygen redox activity and enhanced manganese redox reactions in the initial cycle. Our findings suggest the key role of the local structure in the voltage decay problem and provide insights for material optimizations towards lithium- and manganese-rich cathodes without the voltage decay.

25 ENERGY STORAGE↗
DOE OSTI2023

Narrowing the band gap and suppressing electron–hole recombination in β-Fe 2 O 3 by chlorine doping

Here, the effects of halogen (F, Cl, Br, I, and At) doping in the direct-band-gap β-Fe 2 O 3 semiconductor on its band structures and electron–hole recombination have been investigated by density functional theory. Doping Br, I, and At in β-Fe 2 O 3 leads to transformation from a direct-band-gap semiconductor to an indirect-band-gap semiconductor because their atomic radii are too large; however, F- and Cl-doped β-Fe 2 O 3 remain as direct-band-gap semiconductors. Due to the deep impurity states of the F dopant, this study focuses on the effects of the Cl dopant on the band structures of β-Fe 2 O 3 . Two impurity levels are introduced when Cl is doped into β-Fe 2 O 3 , which narrows the band gap by approximately 0.3 eV. After doping Cl, the light-absorption edge of β-Fe 2 O 3 redshifts from 650 to 776 nm, indicating that its theoretical solar to hydrogen efficiency for solar water splitting increases from 20.6% to 31.4%. In addition, the effective mass of the holes in halogen-doped β-Fe 2 O 3 becomes significantly larger than that in undoped β-Fe 2 O 3 , which may suppress electron–hole recombination.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2024

Designed additive suppresses interpenetration in IRMOF-10

MOF interpenetration leads to reduced surface areas and diminution of guest storage capacity. Here we report an additive strategy to suppress interpenetration within IRMOF-10 resulting in improved surface area and crystallinity upon activation.

Chemistry↗
DOE OSTI2025

Quarkonium suppression in strongly coupled plasmas

Suppression of open heavy quarks and quarkonia in heavy-ion collisions are among the most informative probes of quark-gluon plasma (QGP). Interpreting the full wealth of data obtained from the collision events requires a precise theoretical understanding of the evolution of heavy quarks and quarkonia as they propagate through a strongly coupled plasma. Such calculations require the evaluation of a gauge-invariant correlator of chromoelectric fields. This chromoelectric correlator encodes all the characteristics of QGP that the dissociation and recombination dynamics of quarkonium are sensitive to, which is to say can in principle measure. We review its distinctive qualitative features at weak coupling in QCD up to next-to-leading order and at strong coupling in N = 4 SYM using the AdS/CFT correspondence, as well as its formulation in Euclidean QCD. Furthermore, we report on recent progress in applying our results to the calculation of the final quarkonium abundances after propagating through a cooling droplet of QGP, which illustrates how we may learn about QGP from quarkonium measurements. We devote special attention to how the presence of a strongly coupled plasma modifies the transport description of quarkonium, in comparison to approaches that rely on weak coupling approximations to describe quarkonium dissociation and recombination.

Scheihing-Hitschfeld, Bruno [University of Califor↗
DOE OSTI2020

Fluctuation suppression in microgels by polymer electrolytes

Structural details of thermoresponsive, cationically poly(N-iso-propylacrylamide-co-methacrylamido propyl trimethyl ammonium chloride) microgels and the influence of the anionic electrolyte polystyrene sulfonate (PSS) on the internal structure and dynamics of the cationic microgels have been studied with a combination of small angle neutron scattering (SANS) and neutron spin echo (NSE) spectroscopy. While SANS can yield information on the overall size of the particles and on the typical correlation length inside the particles, studying the segmental polymer dynamics with NSE gives access to more internal details, which only appear due to their effect on the polymer motion. The segmental dynamics of the microgels studied in this paper is to a large extent suppressed by the PSS additive. Possible scenarios of the influence of the polyanions on the microgel structure and dynamics are discussed.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

An improved theory of the response of DIII-D H-mode discharges to static resonant magnetic perturbations and its implications for the suppression of edge localized modes

The plasma response to an externally generated, static, n = 2, resonant magnetic perturbation (RMP) in the pedestal region of DIII-D H-mode discharge #158115 is investigated using a toroidal generalization of the asymptotic matching model presented by Fitzpatrick [Phys. Plasmas 27, 042506 (2020)]. Just as in a recent paper [Q. M. Hu et al., Phys. Plasmas 26, 120702 (2019)], it is hypothesized that the density pump-out phenomenon is due to locked magnetic island chains induced at the bottom of the pedestal, whereas the suppression of edge localized modes is associated with a locked magnetic island chain induced at the top of the pedestal. Neutral penetration inside the last closed magnetic flux-surface is found to have a significant influence on locked magnetic island chain formation at the bottom of the pedestal. It is found that locked island formation at the top of the pedestal is only possible when q95 lies in certain narrow windows. Finally, it is inferred that, in order to successfully induce a locked island chain at the top of the pedestal, an external RMP field-coil system must generate a magnetic field that is simultaneously strongly amplified by the plasma (via the ideal kink response) and has a large resonant component at a rational surface that lies close to the top of the pedestal.

Fitzpatrick, R. (ORCID:0000000162379309)↗
DOE OSTI2020

Modeling q 95 windows for the suppression of edge localized modes by resonant magnetic perturbations in the DIII-D tokamak

A toroidal asymptotic matching model of the response of a tokamak plasma to a static resonant magnetic perturbation (RMP) is used to simulate the n = 3 RMP-induced edge-localized-mode-suppression windows in q 95 that are evident when the plasma current is slowly ramped in DIII-D discharge #145380. All quantities employed in the simulation are derived from experimental measurements, apart from the neutral particle data. Three cases are considered. In the first case, the natural frequencies of tearing modes resonant in the plasma are determined by the ion flows at the corresponding resonant surfaces, which is the prediction of nonlinear tearing mode theory. In the second case, the natural frequencies are determined by the local E x B velocities at the resonant surfaces. In the third case, the natural frequencies are determined by the electron flows at the resonant surfaces, which is the prediction of linear tearing mode theory. The second case gives the best agreement between the simulations and the experimental observations. The first and third cases only lead to partial agreement between the simulations and the observations. In the first case, the lack of complete agreement may be a consequence of using an inaccurate assumption for the neutral particle distribution in the pedestal. In the third case, the lack of complete agreement is probably due to the fact that the response of a tokamak plasma to an RMP is not accurately described by linear tearing mode theory.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2021

Suppression of power losses during laser pulse propagation in underdense plasma slab

For current state-of-the-art terawatt lasers, the primary laser scattering mechanisms in plasma include Forward Raman Scattering (FRS), excitation of plasma waves, and the self-modulational instability (SMI). Using 2D PIC simulations, we demonstrate the dominance of the FRS in the regime with medium-to-low density plasma and non-relativistic laser fields. However, the use of multi-colored lasers with frequency detuning exceeding the plasma frequency, Δω > ω pe , suppresses the FRS. Finally, the laser power can then be transmitted efficiently.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2022

Measuring magnetic flux suppression in high-power laser–plasma interactions

Here, Biermann battery magnetic field generation driven by high power laser–solid interactions is explored in experiments performed with the OMEGA EP laser system. Proton deflectometry captures changes to the strength, spatial profile, and temporal dynamics of the self-generated magnetic fields as the target material or laser intensity is varied. Measurements of the magnetic flux during the interaction are used to help validate extended magnetohydrodynamic (MHD) simulations. Results suggest that kinetic effects cause suppression of the Biermann battery mechanism in laser–plasma interactions relevant to both direct and indirect-drive inertial confinement fusion. Experiments also find that more magnetic flux is generated as the target atomic number is increased, which is counter to a standard MHD understanding.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2023

The competing effects of wave amplitude and collisions on multi-ion species suppression of stimulated Brillouin scattering in inertial confinement fusion Hohlraums

Reduction in stimulated Brillouin scattering (SBS) from National Ignition Facility Hohlraums has been predicted through the use of multi-ion species materials on Hohlraum walls. This approach to controlling SBS is based upon introducing a lighter ion species to the heavier ion species Hohlraum wall in order to greatly increase the ion Landau damping of ion acoustic waves (IAWs). In a collisionless plasma, if the IAWs driven by SBS reach sufficient amplitudes, this increased damping is reduced or even eliminated by ion trapping in the IAWs. Here, the nonlinear behavior of IAWs is simulated with a multi-ion species Vlasov code, including interspecies ion–ion collisions, self-collisions, and electron–ion pitch-angle collisions. The effect of collisions on the trapping of ions and electrons in a large-amplitude IAW is studied in a regime of relevance to current Inertial Confinement Fusion experiments. Our simulations show that collisions can scatter trapped particles out of resonance with the IAW, suppressing trapping and helping to maintain an effective Landau damping of the IAW. The IAW amplitude required to trap particles in the presence of strong collisions is estimated analytically. These estimates are tested for strongly damped IAWs in tantalum oxide and pure helium plasmas. Here our simulations show that, above a threshold amplitude, the damping is reduced by an amount inversely proportional to the wave amplitude. Thus, the success of controlling SBS using a multispecies plasma may depend sensitively on laser power and pulse length.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2023

Defect-mediated diffusion of implanted Mg in GaN: Suppressing dopant redistribution by sequential thermal and microwave annealing

The diffusion behavior of Mg in Mg/N co-implanted GaN is investigated in response to a set of annealing conditions and methodologies, namely, 1000 °C/30 min thermal anneal, by high-temperature pulsed gyrotron microwave annealing at 1420 or 1500 °C, or by thermal and microwave annealing, sequentially. After 1000 °C annealing, the diffusion of Mg in GaN is found to be negligible, as measured by secondary ion mass spectrometry. Annealing by gyrotron microwave annealing alone induces the diffusion of Mg at a rate on the order of 10 −12 cm 2 /s. However, the use of a thermal anneal before microwave gyrotron annealing reduces this rate by an order of magnitude to 10 −13 cm 2 /s. We find that a model that considers Mg diffusion from an inhomogeneous medium that contains a defect-rich implanted region near-surface to a relatively pristine region below the implant range better explains the observed diffusion behavior than a conventional model that assumes a homogeneous medium. By analyzing the diffusion behavior using the Boltzmann–Matano method, we present a discussion of reduction in [V Ga ] by thermal annealing at 1000 °C, leading to a suppressed diffusion coefficient during subsequent high-temperature annealing relative to diffusion after 1420/1500 °C annealing alone. This effect holds potential for improvement in the precision of selectively doped regions for future applications based on the (Al)GaN material system. An improved field profile control in real devices can increase the breakdown and current-handling capabilities in power electronic applications.

Meyers, V.↗
DOE OSTI2023

Suppressing parametric instabilities in direct-drive inertial-confinement-fusion plasmas using broadband laser light

It has long been recognized that broadband laser light has the potential to control parametric instabilities in inertial-confinement-fusion (ICF) plasmas. Here, we use results from laser-plasma-interaction simulations to estimate the bandwidth requirements for mitigating the three predominant classes of instabilities in direct-drive ICF implosions: cross-beam energy transfer (CBET), two-plasmon decay (TPD), and stimulated Raman scattering (SRS). We find that for frequency-tripled, Nd:glass laser light, a bandwidth of 8.5 THz can significantly increase laser absorption by suppressing CBET, while ∼13 THz is needed to mitigate absolute TPD and SRS on an ignition-scale platform. None of the glass lasers used in contemporary ICF experiments, however, possess a bandwidth greater than 1 THz and reaching larger values requires the use of an auxiliary broadening technique such as optical parametric amplification or stimulated-rotational-Raman scattering. An arguably superior approach is the adoption of an argon-fluoride (ArF) laser as an ICF driver. Besides having a broad bandwidth of ∼10 THz, the ArF laser also possesses the shortest wavelength (193 nm) that can scale to the high energy/power required for ICF—a feature that helps to mitigate parametric instabilities even further. We show that these native properties of ArF laser light are sufficient to eliminate nearly all CBET scattering in a direct-drive target and also raise absolute TPD and SRS thresholds well above those for broadband glass lasers. The effective control of parametric instabilities with broad bandwidth is potentially a “game changer” in ICF because it would enable higher laser intensities and ablation pressures in future target designs.

Bates, J. W. (ORCID:0000000188087240)↗
DOE OSTI2024

Explosively driven Richtmyer–Meshkov instability jet suppression and enhancement via coupling machine learning and additive manufacturing

The ability to control the behavior of fluid instabilities at material interfaces, such as the shock-driven Richtmyer–Meshkov instability, is a grand technological challenge with a broad number of applications ranging from inertial confinement fusion experiments to explosively driven shaped charges. In this work, we use a linear-geometry shaped charge as a means of studying methods for controlling material jetting that results from the Richtmyer–Meshkov instability. A shaped charge produces a high-velocity jet by focusing the energy from the detonation of high explosives. The interaction of the resulting detonation wave with a hollowed cavity lined with a thin metal layer produces the unstable jetting effect. By modifying the characteristics of the detonation wave prior to striking the lined cavity, the kinetic energy of the jet can be enhanced or reduced. Modifying the geometry of the liner material can also be used to alter jetting properties. We apply optimization methods to investigate several design parameterizations for both enhancing or suppressing the shaped-charge jet. This is accomplished using 2D and 3D hydrodynamic simulations to investigate the design space that we consider. We also apply new additive manufacturing methods for producing the shaped-charge assemblies, which allow for the experimental testing of complicated design geometries obtained through computational optimization. We present a direct comparison of our optimized designs with experimental results carried out at the High Explosives Application Facility at Lawrence Livermore National Laboratory.

36 MATERIALS SCIENCE↗