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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 OSTI2024

From shockwaves to the gravitational memory effect

We study the relationship between shockwave geometries and the gravitational memory effect in four-dimensional asymptotically flat spacetime. In particular, we show the ’t Hooft commutation relations of shockwave operators are equivalent to the commutation relation between soft and Goldstone modes parametrizing a sector of the gravitational phase space. We demonstrate this equivalence via a diffeomorphism that takes a shockwave metric to a metric whose transverse traceless component is the gravitational memory. The shockwave momentum in ’t Hooft’s analysis is related to the soft graviton mode, which is responsible for the memory effect, while the shift in the shockwave position is related to the Goldstone mode. This equivalence opens new directions to utilize the gravitational memory effect to explore the observational implications of shockwave geometries in flat space.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2020

Shockwave Arrival Times from Operation Redwing and Operation Upshot-Knothole

Back in the 1940s, 50s, and 60s, 210 nuclear tests were conducted in the atmosphere. As part of the testing program, EG&G performed shockwave arrival-time measurements for different shots in different operations using pressure transducers at different distances from ground zero. They then developed correlations unique to each set of data. They did not attempt to correlate all data onto one curve. As a fireball moves, material is picked up and pulled in, which is called entrainment. This extra material increases the mass of the fireball, and as the energy is spread out over a larger and larger mass, the specific internal energy of the fireball gases drops, which causes the temperature to drop as well. When the energy in the solid angle of a spherical shockwave hits the surface, it is reflected. Shortly thereafter, it catches up with the outward-moving shockwave and re-combines with it, causing it to expand at a slightly faster rate. As the shockwave grows, it approaches a hemispherical shape. The purpose of this project is to demonstrate that the shockwave arrival-time data can, in fact, be correlated onto a single function when the shockwave time-dependent solution is modified to include a geometric factor, θ, and is corrected for an entrainment coefficient.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗
DOE OSTI2024

Rindler fluids from gravitational shockwaves

We study a correspondence between gravitational shockwave geometry and its fluid description near a Rindler horizon in Minkowski spacetime. Utilizing the Petrov classification that describes algebraic symmetries for Lorentzian spaces, we establish an explicit mapping between a potential fluid and the shockwave metric perturbation, where the Einstein equation for the shockwave geometry is equivalent to the incompressibility condition of the fluid, augmented by a shockwave source. Then we consider an Ansatz of a stochastic quantum source for the potential fluid, which has the physical interpretation of shockwaves created by vacuum energy fluctuations. Under such circumstance, the Einstein equation, or equivalently, the incompressibility condition for the fluid, becomes a stochastic differential equation. By smearing the quantum source on a stretched horizon in a Lorentz invariant manner with a Planckian width (similarly to the membrane paradigm), we integrate fluctuations near the Rindler horizon to find an accumulated effect of the variance in the round-trip time of a photon traversing the horizon of a causal diamond.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

QCD–Gravity Double Copy in Regge Asymptotics: From \(2\rightarrow n\) Amplitudes to Radiation in Shockwave Collisions

This paper discusses multi-particle production in QCD and in gravity at ultrarelativistic energies, their double-copy relations, and strong parallels in emergent shockwave dynamics. Dispersive techniques are applied to derive the BFKL equation for multi-gluon production in Regge asymptotics. Identical methods apply in gravity and are captured by a gravitational Lipatov equation. The building blocks in both cases are Lipatov vertices and reggeized propagators satisfying double-copy relations; in gravity, Weinberg’s soft theorem is recovered as a limit of the Lipatov framework. BFKL evolution in QCD generates wee parton states of maximal occupancy characterized by an emergent semi-hard saturation scale. Renormalization group equations in the Color Glass Condensate (CGC) EFT describe wee parton correlations and their rapidity evolution. A shockwave picture of deeply inelastic scattering and hadron–hadron collisions follows, with multi-particle production described by Cutkosky’s rules in strong time-dependent fields. Gluon radiation in the CGC EFT has a double copy in gravitational shockwave collisions, with a similar correspondence applicable between gluon and graviton shockwave propagators. Possible extensions of this semi-classical double copy are outlined for computing multi-particle production in gravitational shockwave collisions, self-force and tidal contributions, and classical and quantum noise in the focusing of geodesics.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
NASA NTRS2014

Shockwave Consolidation of Nanostructured Thermoelectric Materials

Nanotechnology based thermoelectric materials are considered attractive for developing highly efficient thermoelectric devices. Nano-structured thermoelectric materials are predicted to offer higher ZT over bulk materials by reducing thermal conductivity and increasing electrical conductivity. Consolidation of nano-structured powders into dense materials without losing nanostructure is essential towards practical device development. Using the gas atomization process, amorphous nano-structured powders were produced. Shockwave consolidation is accomplished by surrounding the nanopowder-containing tube with explosives and then detonating. The resulting shock wave causes rapid fusing of the powders without the melt and subsequent grain growth. We have been successful in generating consolidated nano-structured bismuth telluride alloy powders by using the shockwave technique. Using these consolidated materials, several types of thermoelectric power generating devices have been developed. Shockwave consolidation is anticipated to generate large quantities of nanostructred materials expeditiously and cost effectively. In this paper, the technique of shockwave consolidation will be presented followed by Seebeck Coefficient and thermal conductivity measurements of consolidated materials. Preliminary results indicate a substantial increase in electrical conductivity due to shockwave consolidation technique.

Prasad, Narasimha S.↗
DOE OSTI2020

Shockwave dissipation by interface-dominated porous structures

The advent of additive manufacturing (AM) has enabled topological control of structures at the micrometer scale, transforming the properties of polymers for a variety of applications. Examples include tailored mechanical responses, acoustic properties, and thermal properties. Porous polymer materials are a class of materials used for shock and blast mitigation, yet they frequently possess a lack of structural order and are largely developed and evaluated via trial-and-error. Here, we demonstrate control of shockwave dissipation through interface-dominated structures prepared by AM using 2-photon polymerization. A fractal structure with voids, or free surfaces, arranged less than 100 μm apart, allows for rarefaction interactions on the timescale of the shockwave loading. Simulations and dynamic x-ray phase contrast imaging experiments show that fractal structures with interfaces assembled within a “critical” volume reduce shockwave stress and wave velocity by over an order of magnitude within the first unit cell.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Universal features of 2 → N scattering in QCD and gravity from shockwave collisions

A remarkable double-copy relation of Einstein gravity to QCD in Regge asymptotics is Γ μ ν = 1 2 C μ C ν − 1 2 N μ N ν , where Γ μ ν is the gravitational Lipatov vertex in the 2 → 3 graviton scattering amplitude, C μ its Yang-Mills counterpart, and N μ the QED bremsstrahlung vertex. In QCD, the Lipatov vertex is a fundamental building block of the BFKL equation describing the 2 → N scattering of gluons at high energies. Likewise, the gravitational Lipatov vertex is a key ingredient in a 2D effective field theory framework describing trans-Planckian 2 → N graviton scattering. We construct a quantitative correspondence between a semiclassical Yang-Mills framework for radiation in gluon shockwave collisions and its counterpart in general relativity. In particular, we demonstrate the Lipatov double copy in a dilute-dilute approximation corresponding to R S , L , R S , H ≪ b , where R S , L , R S , H are the respective emergent Schwarzchild radii generated in shockwave collisions and b is the impact parameter. We outline extensions of the correspondence developed here to the dilute-dense computation of gravitational wave radiation in the close vicinity of one of the black holes, the construction of graviton propagators in the shockwave background, and a renormalization group approach to compute 2 → N amplitudes that incorporates graviton Reggeization and coherent graviton multiple scattering. Published by the American Physical Society 2024

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
NASA NTRS1992

Stepwise shockwave velocity determinator

To provide an uncomplicated and inexpensive method for measuring the far-field velocity of a surface shockwave produced by an explosion, a stepwise shockwave velocity determinator (SSVD) was developed. The velocity determinator is constructed of readily available materials and works on the principle of breaking discrete sensors composed of aluminum foil contacts. The discrete sensors have an average breaking threshold of approximately 7 kPa. An incremental output step of 250 mV is created with each foil contact breakage and is logged by analog-to-digital instrumentation. Velocity data obtained from the SSVD is within approximately 11 percent of the calculated surface shockwave velocity of a muzzle blast from a 30.06 rifle.

Roth, Timothy E.↗
DOE OSTI2025

Single-shot in-line x-ray phase-contrast imaging of void-shockwave interactions in fusion energy materials

Recent breakthroughs in nuclear fusion, specifically the report of reactions exceeding scientific breakeven at the National Ignition Facility (NIF), highlight the potential of inertial fusion energy (IFE) as a sustainable and virtually limitless energy source. However, further progress in IFE requires characterization of defects in ablator materials and how they affect fuel capsule compression. Voids within the ablator can degrade energy yield, but their impact on the density distribution has primarily been studied through simulations, with limited high-resolution experimental validation. To address this, we used the x-ray free-electron laser (XFEL) at the matter in extreme conditions (MECs) instrument at the Linac coherent light source (LCLS) to capture 2D x-ray phase-contrast (XPC) images of a void-bearing sample with a composition similar to inertial confinement fusion (ICF) ablators. By driving a compressive shockwave through the sample using MEC's long-pulse laser system, we analyzed how voids influence shockwave propagation and density distribution during compression. To quantify this impact, we extracted phase information using two phase retrieval algorithms. First, we applied the contrast transfer function (CTF) method, paired with Tikhonov regularization and a fast optimization approach to generate an initial phase estimate. We then refined the result using a projected gradient descent (PGD) method that works directly with the sample's refractive index. Comparing these results with radiation adaptive grid Eulerian (xRAGE) radiation hydrodynamic simulations enables identification of model validation needs or improvements. By calculating phase maps in situ, it becomes possible to reconstruct areal density maps, improving understanding of laser-capsule interactions and advancing IFE research.

Hodge, D. S. [Colorado State Univ., Fort Collins, ↗
NASA NTRS1972

Shockwave determination of the shear velocity at very high pressures.

Description of a proposed shockwave experiment that may provide some understanding on the behavior of planet core materials in the presence of high temperatures and pressures. Shockwave experimentation is shown to offer promise of revealing some information on shear velocity behavior at high pressures, and its relevance to properties of planet interiors consists in that abrupt changes in shear velocities at boundary layers could be experimentally confirmed where abrupt changes in density are suspected from seismic interpretation.

Anderson, O. L.↗
DOE OSTI2025

The Effects of Shockwave Pressures on Ultrafast Vibrational Energy Transfer in BNFF, a Hydrogen-Free Energetic Material

Energy conversion in energetic materials from shock-wave-induced lattice compression to bond breaking critically depends on vibrational coupling and energy transfer between intra- and intermolecular vibrations, though the details of the mechanisms remain unknown. Herein, we indirectly tune the strength of intermolecular interactions in 3,4-bis(3-nitrofurazan-4-yl)furoxan (BNFF), a hydrogen-free energetic material characterized by van der Waals interactions, by applying high static pressure using a diamond anvil cell and monitoring vibrational energy transfer (VET) with ultrafast broadband infrared pump–probe spectroscopy. As BNFF is compressed from ambient pressure to 9 GPa, we find that VET accelerates by ∼ 0.9 ps/GPa. Density functional theory is applied in tandem with experiments to assign mode character and elucidate VET pathways. In conclusion, we find that furazan ring O–N–O vibrations, which are high-frequency detonation-relevant vibrational modes, experience increased sensitivity to lattice compression under shockwave pressures. These findings provide new mechanistic insight into how intermolecular interactions govern the rate and selectivity of VET.

Energy transfer↗
DOE OSTI2024

Mechanochemically responsive polymer enables shockwave visualization

Abstract Understanding the physical and chemical response of materials to impulsive deformation is crucial for applications ranging from soft robotic locomotion to space exploration to seismology. However, investigating material properties at extreme strain rates remains challenging due to temporal and spatial resolution limitations. Combining high-strain-rate testing with mechanochemistry encodes the molecular-level deformation within the material itself, thus enabling the direct quantification of the material response. Here, we demonstrate a mechanophore-functionalized block copolymer that self-reports energy dissipation mechanisms, such as bond rupture and acoustic wave dissipation, in response to high-strain-rate impacts. A microprojectile accelerated towards the polymer permanently deforms the material at a shallow depth. At intersonic velocities, the polymer reports significant subsurface energy absorption due to shockwave attenuation, a mechanism traditionally considered negligible compared to plasticity and not well explored in polymers. The acoustic wave velocity of the material is directly recovered from the mechanochemically-activated subsurface volume recorded in the material, which is validated by simulations, theory, and acoustic measurements. This integration of mechanochemistry with microballistic testing enables characterization of high-strain-rate mechanical properties and elucidates important insights applicable to nanomaterials, particle-reinforced composites, and biocompatible polymers.

Science & Technology - Other Topics↗
NASA NTRS1973

Shockwave-boundary layer interference heating analysis.

Interference heating correlations have been developed based on existing wind tunnel test data taken with simple configurations such as wedge/flat plate and compression corner models. For turbulent flow, peak interference heating was first correlated with shock strength (pressure ratio across shock wave) and then as a function of Reynolds number. The peak interference Stanton number was found to exhibit the same Reynolds number and Prandtl number characteristics as the Stanton number variation for undisturbed flow over a flat plate. Similar correlations were developed for laminar flow. Results indicated that for laminar flow at higher Reynolds number, the impinging shockwave may act as a boundary layer trip and cause boundary layer transition resulting in high interference heating. The correlations derived in this study can be used to scale wind tunnel model test data to a full-scale space vehicle at supersonic or hypersonic flight conditions.

Hung, F. T.↗
NASA NTRS2018

Characterization of CO Thermochemistry in Incident Shockwaves

Incident shock waves in pure CO have been characterized in the Electric Arc Shock Tube facility at NASA Ames Research Center. Spectrally and spatially resolved emission spectra characterize radiative signatures from CO in the VUV (Vacuum Ultra-Violet) and mid-infrared and atomic carbon and C2 in the visible. CO absorption of a single vibrational line is also measured with a tunable diode laser. The experimental data analyzed here are at a pressure of 0.25 Torr in the driven section and span a shock velocity range from 3.4-9.5 km/s. The emission and absorption signals are analyzed to extract temperature relaxation behind the shock which is used to derive the rate of CO dissociation. The emission spectra are compared to results using different kinetic parameters for CO dissociation and C2 dissociation and exchange. Different rates from the literature are found to match the data from 3.4-6.6 km/s and 6.6-9.5 km/s. Areas for improvement in CO and C2 radiation modeling are suggested on the basis of the analysis.

Entry↗
NASA NTRS2018

Characterization of CO Thermochemistry in Incident Shockwaves

Incident shock waves in pure CO have been characterized in the Electric Arc ShockTube facility at NASA Ames Research Center. Spectrally and spatially resolved emissionspectra characterize radiative signatures from CO in the VUV and mid-infrared and atomiccarbon and C2 in the visible. CO absorption of a single vibrational line is also measuredwith a tunable diode laser. The experimental data analyzed here are at a pressure of 0.25Torr in the driven section and span a shock velocity range from 3.4-9.5 km/s. The emissionand absorption signals are analyzed to extract temperature relaxation behind the shockwhich is used to derive the rate of CO dissociation. The emission spectra are compared toresults using different kinetic parameters for CO dissociation and C2 dissociation andexchange. Different rates from the literature are found to match the data from 3.4-6.6 km/sand 6.6-9.5 km/s. Areas for improvement in CO and C2 radiation modeling are suggested onthe basis of the analysis.

CO↗
DOE OSTI2021

Effect of X-ray free-electron laser-induced shockwaves on haemoglobin microcrystals delivered in a liquid jet

X-ray free-electron lasers (XFELs) enable obtaining novel insights in structural biology. The recently available MHz repetition rate XFELs allow full data sets to be collected in shorter time and can also decrease sample consumption. However, the microsecond spacing of MHz XFEL pulses raises new challenges, including possible sample damage induced by shock waves that are launched by preceding pulses in the sample-carrying jet. We explored this matter with an X-ray-pump/X-ray-probe experiment employing haemoglobin microcrystals transported via a liquid jet into the XFEL beam. Diffraction data were collected using a shock-wave-free single-pulse scheme as well as the dual-pulse pump-probe scheme. The latter, relative to the former, reveals significant degradation of crystal hit rate, diffraction resolution and data quality. Crystal structures extracted from the two data sets also differ. Since our pump-probe attributes were chosen to emulate EuXFEL operation at its 4.5 MHz maximum pulse rate, this prompts concern about such data collection.

59 BASIC BIOLOGICAL SCIENCES↗