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DOE OSTI2021

Modeling Subsurface Explosions Recorded on a Distributed Fiber Optic Sensor

Fiber optic distributed acoustic sensors (DAS) are becoming a widely used tool for seismic sensing. Here we examine recordings of two subsurface chemical explosions, DAG-1 and DAG-3, each of which was about one metric ton (TNT equivalent), that were recorded from a helical fiber installed in two boreholes 80 m away from the source location. Several clear phases including the initial P wave, a weak S wave, and a surface reflected P wave are observed on the helical DAS data. We estimate a velocity model using arrival times measured from the fiber. The DAS waveform data were compared with colocated accelerometers at specific depths in both frequency and time domains. Furthermore, the spectra of the DAS data matched spectra estimated from the accelerometer records. Comparisons of observed waveform shape between the accelerometer records and the fiber measurements (strain-rate) show reasonable agreement except for the data near the event depth. The DAS data and the accelerometer agreed in relative amplitudes but we had difficulties in matching absolute amplitudes, possibly due to errors in metadata. Synthetic strain-rate waveforms were calculated using a 2D wavenumber algorithm and matched the waveform shape and relative amplitudes. In general, DAS is effective at recording strong ground motions at high spatial density. Comparison of the synthetic seismograms with observed data indicate that the waveforms are not consistent with a pure isotropic explosion source and that the observed S waves originate from very near the source region.

58 GEOSCIENCES↗

NASA NTRS1982

The use of the PUCOT for elastic modulus measurements on intermetallics at high temperatures

The piezoelectric ultrasonic composite oscillator technique (PUCOT) is being applied to measure the elastic constants of the aluminides in the temperature ranges 300 to 1700 K (CoAl and NiAl) and 300 to 1500 K (FeAl). The PUCOT consists of piezoelectric quartz drive and gauge crystals to excite longitudinal or torsional ultrasonic (80 kHz) resonant stress waves in the specimen and alumina spacer rod of appropriate resonant lengths. The resonant system is driven by a closed loop oscillator which maintains a constant gauge voltage and hence constant strain amplitude in the specimen. While the specimen is heated at 20 K/h the resonant period is measured continuously. The elastic moduli are calculated from these values of the resonant period and accurate determinations of specimen length. The technique is described and some results given.

Wolfenden, A.↗

DOE OSTI2024

Gravitational-wave and Gravitational-wave Memory Signatures of Core-collapse Supernovae

Abstract In this paper, we calculate the energy, signal-to-noise ratio (SNR), detection range, and angular anisotropy of the matter, matter memory, and neutrino memory gravitational-wave (GW) signatures of 21 three-dimensional initially nonrotating core-collapse supernova (CCSN) models carried to late times. We find that inferred energy, SNR, and detection range are angle-dependent quantities, and that the spread of possible energy, signal to noise, and detection ranges across all viewing angles generally increases with progenitor mass. When examining the low-frequency matter memory and neutrino memory components of the signal, we find that the neutrino memory is the most detectable component of a CCSN GW signal, and that DECIGO is best equipped to detect both matter memory and neutrino memory. Moreover, we find that the polarization angle between the h + and h × strains serves as a unique identifier of matter and neutrino memory. Finally, we develop a Galactic density- and stellar mass-weighted formalism to calculate the rate at which we can expect to detect CCSN GW signals with the Advanced Laser Interferometer Gravitational-Wave Observatory (aLIGO). When considering only the matter component of the signal, the aLIGO detection rate is around 65% of the total Galactic supernova rate, but increases to 90% when incorporating the neutrino memory component. We find that all future detectors (Einstein Telescope, Cosmic Explorer, DECIGO) will be able to detect CCSN GW signals from the entire Galaxy, and for the higher-mass progenitors even into the Local Group of galaxies.

Choi, Lyla (ORCID:0000000153860133)↗

DOE OSTI2025

Superconducting Levitated Detector of Gravitational Waves

A magnetically levitated mass couples to gravity and can act as an effective gravitational wave detector. We show that a superconducting sphere levitated in a quadrupolar magnetic field, when excited by a gravitational wave, will produce magnetic field fluctuations that can be read out using a flux tunable microwave resonator. With a readout operating at the standard quantum limit, such a system could achieve broadband strain noise sensitivity of h ≲ 10 − 20 / Hz for frequencies of 1 kHz–1 MHz, opening new corridors for astrophysical probes of new physics. Published by the American Physical Society 2025

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

NASA NTRS1981

A New Tool for Industry

Ultrasonic P2L2 bolt monitor is a new industrial tool, developed at Langley Research Laboratory, which is lightweight, portable, extremely accurate because it is not subject to friction error, and it is cost-competitive with the least expensive of other types of accurate strain monitors. P2L2 is an acronym for Pulse Phase Locked Loop. The ultrasound system which measures the stress that occurs when a bolt becomes elongated in the process of tightening, transmits sound waves to the bolt being fastened and receives a return signal indicating changes in bolt stress. Results are translated into a digital reading of the actual stress on the bolt. Device monitors the bolt tensioning process on mine roof bolts that provide increased safety within the mine. Also has utility in industrial applications.

Source record↗

NASA NTRS2007

Dog-Bone Horns for Piezoelectric Ultrasonic/Sonic Actuators

A shape reminiscent of a dog bone has been found to be superior to other shapes for mechanical-amplification horns that are components of piezoelectrically driven actuators used in a series of related devices denoted generally as ultrasonic/sonic drill/corers (USDCs). The first of these devices was reported in Ultrasonic/Sonic Drill/Corers With Integrated Sensors (NPO-20856), NASA Tech Briefs, Vol. 25, No. 1 (January 2001), page 38. The dog-bone shape was conceived especially for use in a more recent device in the series, denoted an ultrasonic/ sonic gopher, that was described in Ultrasonic/Sonic Mechanisms for Drilling and Coring (NPO-30291), NASA Tech Briefs, Vol. 27, No. 9 (September 2003), page 65. The figure shows an example of a dog-bone-shaped horn and other components of an ultrasonic gopher. Prerequisite to a meaningful description of this development is an unavoidably lengthy recapitulation of the principle of operation of a USDC and, more specifically, of the ultrasonic/sonic gopher as described previously in NASA Tech Briefs. The ultrasonic actuator includes a stack of piezoelectric rings, the horn, a metal backing, and a bolt that connects the aforementioned parts and provides compressive pre-strain to the piezoelectric stack to prevent breakage of the rings during extension. The stack of piezoelectric rings is excited at the resonance frequency of the overall ultrasonic actuator. Through mechanical amplification by the horn, the displacement in the ultrasonic vibration reaches tens of microns at the tip of the horn. The horn hammers an object that is denoted the free mass because it is free to move longitudinally over a limited distance between hard stops: The free mass bounces back and forth between the ultrasonic horn and a tool bit (a drill bit or a corer). Because the longitudinal speed of the free mass is smaller than the longitudinal speed of vibration of the tip of the horn, contact between the free mass and the horn tip usually occurs at a phase of the vibration favorable to transfer of momentum from the horn to the free mass. Therefore, the free mass picks up momentum and is accelerated back to the tool bit. Upon impact of the free mass on the tool bit, momentum is transferred to the tool bit. The impacts of the free mass on the tool bit repeat at a sonic frequency that can range from tens of hertz to about 1 kHz. The shock waves caused by the impacts of the free mass propagate to the interface between the tool bit and the medium (typically, rock, ice, or other brittle material) to be drilled or cored. The medium becomes fractured when its ultimate strain is exceeded at the medium/tool-bit interface. This concludes the description of the principle of operation.

Sherrit, Stewart↗

DOE OSTI2021

Probing the lattice structure of dynamically compressed and released single crystal iron through the alpha to epsilon phase transition

In this work, experiments using broadband Laue x-ray diffraction (XRD) were used to examine the lattice structure of dynamically compressed [100]-oriented single crystal iron samples at the Dynamic Compression Sector at the Advanced Photon Source. These experiments used 1 μm thick iron single crystal samples sandwiched between a polyimide ablator and a polycarbonate window. A 100 J, 10 ns duration laser pulse incident on the polyimide ablator was used to shock compress the iron samples to initial stresses greater than 25 GPa, exceeding the ~13 GPa alpha (body-centered-cubic or bcc structure) to epsilon (hexagonal-close-packed or hcp structure) phase transition stress. XRD measurements were performed at various times relative to the shock wave entering the iron sample: early times, <~150 ps while the initial shock waves propagated through the iron; intermediate times, after the iron equilibrated with the ablator and window reaching a plateau stress state (12 or 17 GPa) lasting several nanoseconds; and late times, during uniaxial strain release. The early time measurements show that in <~150 ps, the high-pressure hcp phase is relaxed with a c/a ratio of 1.61, contrary to previous laser shock experiments where a c/a ratio of 1.7 was inferred. In the plateau stress state and partially released states, XRD measurements showed that the hcp structure retained a c/a ratio of 1.61 with no observable changes in the microstructure. Upon stress release at ~1 GPa/ns release rate, the reverse phase transition (hcp to bcc) to the original single crystal orientation (implying a transformation memory effect) was observed to reach completion somewhere between 13 and 11 GPa, indicating little stress hysteresis under rapid uniaxial strain release. A similar memory effect for the reverse hcp to bcc transformation has been previously observed under hydrostatic compression. However, the bcc/hcp orientation relationships differ somewhat between dynamic and static compression experiments, implying that the transformation pathway under uniaxial dynamic strain differs from the Burgers mechanism.

36 MATERIALS SCIENCE↗

DOE OSTI2022

Fully Distributed Multi-Material Magnetic Sensing Structures for Multiparameter DAS Applications

This dissertation demonstrates the first of its kind distributed magnetic field sensor based on a fiber optic distributed acoustic sensing (DAS) scheme. Ferromagnetic nickel and Metglas® were dispersed internally within a fiber optic preform and then drawn on an in-house fiber optic draw tower to lengths in the kilometers. Due to the close proximity of the ferromagnetic metals and fiber optic core, the magnetostrictive strain response of the ferromagnetic materials when exposed to a magnetic field would perturbate within the fiber cladding and transfer that strain, internally, to the fiber optic core. Strain resulting from the magnetostrictive effect allows the DAS based sensor to accurately translate strain into readable magnetic field data. Due to the high sensitivity seen in this sensor design, multiparameter sources, acoustic and magnetic fields, were tested and validated and a three dimensional magnetic-field vector sensor was proposed. Numerical analysis of the novel sensor design was first implemented using COMSOL Multiphysics, where inputs such as magnetostrictive element shape, size, distance, and number were first investigated. Upon optimizing system constraints, the sensor design was further modified such that single mode operation was consistent across multiple fiber draws while retaining high strain transfer from the ferromagnetic elements to the fiber optic core. Ferromagnetic material selection was evaluated as a function of the saturation magnetostriction constants and a total of 4 modules were used to fully characterize the complex physics involved in this sensor design. All fabrication and testing were performed in-house using a full scale 3-story fiber draw tower and custom environmental testing stations to imitate naturally occurring events such as magnetic or acoustic point sources. A unique stacking method was used to embed ferromagnetic nickel and Metglas® into a fiber optic preform which when combined with a custom fiber draw process resulted in consistent multi-material fibers drawn to lengths of 1-km. In-house testing facilities included different types of electromagnetic generators, in addition to a soil test bed, and an outdoor test bed which allowed 100 meters of fiber to be tested simultaneously. All tested sensors demonstrated high strain transfer capabilities on the order of 0.01-10 μϵ depending on the materials used, ferromagnetic rod number, and core to metal spacing. Due to the sensitivity of the system the difference between AC and DC was distinct, and directional magnetostriction was studied. Transverse and longitudinal magnetic wave propagation was controlled through a solenoid and rectangular Helmholtz coil, both built in-house. A three-dimensional magnetic field vector sensor was proposed due to the success of the magnetic field sensor, and a design was proposed and initially tested to validate direction as a function of field strength and distance. To summarize, this dissertation explores the first fully distributed magnetic field sensor using DAS based techniques and one of the first multi-material fiber draw processes which can produce consistent single mode fiber up to 1-km. Due to extensive FEA modeling, multiple iterations of the magnetic sensor were fully characterized and an equation describing the relationship between sensor design and strain transfer has been created and validated experimentally. Multi-parameter tests including acoustic and magnetic fields were implemented and an algorithm was developed to separate the mixed signals. Finally, a test was performed to demonstrate the feasibility of sensing magnetic fields directionally. Cumulative results demonstrate a high-quality sensor alternative to current designs which may surpass other magnetic sensors due to innate multi-parameter capabilities, in addition to the inexpensive production cost and extremely long operating lengths.

02 PETROLEUM↗

NASA NTRS1968

Electro-optic modulator for infrared laser using gallium arsenide crystal

Gallium arsenide electro-optic modulator used for infrared lasers has a mica quarter-wave plate and two calcite polarizers to amplitude or phase modulate an infrared laser light source in the wavelength range from 1 to 3 microns. The large single crystal has uniformly high resistivities, is strain free, and comparable in quality to good optical glass.

Walsh, T. E.↗

NASA NTRS1973

Response of panels to turbulence-induced, surface-pressure fluctuations and resulting acoustic radiation to the flow field.

The response of finite rectangular panels, excited by turbulent boundary layers and the resulting acoustical radiation into the flow field is studied. The method of normal modes and the technique of spectral analysis are used to compute the power spectra of the panel amplitude and strain response. Computed results are compared with the corresponding response measurements for panels exposed to attached and separated flows at supersonic speeds and attached flow at subsonic speeds. The thin plate and the convected wave equations are coupled through the boundary condition on the panel to give a formula for the radiation pressure power spectra. A formula for the acoustical damping ratio of the panel is obtained through the principle of virtual work.-

Chyu, W. J.↗

NASA NTRS1977

Impact behavior of graphite-epoxy simulated fan blades

The response of a graphite-epoxy material, Modmor II/PR-286, to foreign object impact was investigated by impacting spherical projectiles of three different materials - gelatin, ice, and steel - on simulated blade specimens. Visual and metallographic inspection revealed three damage mechanisms: penetration, leading edge bending failure, and stress wave delamination and cracking. The steel projectiles caused penetration damage regardless of the impact location and angle. For the ice and gelatin particles impacting the leading edge, failure was due to large local bending strains, resulting in significant material removal and delamination damage.

Cook, T. S.↗

DOE OSTI2021

Techniques for studying materials under extreme states of high energy density compression

The properties of materials under extreme conditions of pressure and density are of key interest to a number of fields, including planetary geophysics, materials science, and inertial confinement fusion. In geophysics, the equations of state of planetary materials, such as hydrogen and iron, under ultrahigh pressure and density provide a better understanding of their formation and interior structure [Celliers et al., “Insulator-metal transition in dense fluid deuterium,” Science 361, 677–682 (2018) and Smith et al., “Equation of state of iron under core conditions of large rocky exoplanets,” Nat. Astron. 2, 591–682 (2018)]. The processes of interest in these fields occur under conditions of high pressure (100 GPa–100 TPa), high temperature (>3000 K), and sometimes at high strain rates (>103 s−1) depending on the process. With the advent of high energy density (HED) facilities, such as the National Ignition Facility (NIF), Linear Coherent Light Source, Omega Laser Facility, and Z, these conditions are reachable and numerous experimental platforms have been developed. To measure compression under ultrahigh pressure, stepped targets are ramp-compressed and the sound velocity, measured by the velocity interferometer system for any reflector diagnostic technique, from which the stress-density of relevant materials is deduced at pulsed power [M. D. Knudson and M. P. Desjarlais, “High-precision shock wave measurements of deuterium: Evaluation of exchange-correlation functionals at the molecular-to-atomic transition,” Phys. Rev. Lett. 118, 035501 (2017)] and laser [Smith et al., “Equation of state of iron under core conditions of large rocky exoplanets,” Nat. Astron. 2, 591–682 (2018)] facilities. To measure strength under high pressure and strain rates, experimenters measure the growth of Rayleigh–Taylor instabilities using face-on radiography [Park et al., “Grain-size-independent plastic flow at ultrahigh pressures and strain rates,” Phys. Rev. Lett. 114, 065502 (2015)]. The crystal structure of materials under high compression is measured by dynamic x-ray diffraction [Rygg et al., “X-ray diffraction at the national ignition facility,” Rev. Sci. Instrum. 91, 043902 (2020) and McBride et al., “Phase transition lowering in dynamically compressed silicon,” Nat. Phys. 15, 89–94 (2019)]. Medium range material temperatures (a few thousand degrees) can be measured by extended x-ray absorption fine structure techniques, Yaakobi et al., “Extended x-ray absorption fine structure measurements of laser-shocked V and Ti and crystal phase transformation in Ti,” Phys. Rev. Lett. 92, 095504 (2004) and Ping et al., “Solid iron compressed up to 560 GPa,” Phys. Rev. Lett. 111, 065501 (2013), whereas more extreme temperatures are measured using x-ray Thomson scattering or pyrometry. This manuscript will review the scientific motivations, experimental techniques, and the regimes that can be probed for the study of materials under extreme HED conditions.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

NASA NTRS2024

Investigation into the Origin of the RF Phase Noise for the LISA Laser Transmitter

The Laser Interferometer Space Antenna (LISA) mission is a collaborative consortium led by the European Space Agency (ESA)in cooperation with the National Aeronautics and Space Administration (NASA). LISA’s goal is to capture gravitational wave events, such as spacetime distortions caused by massive orbiting bodies. Multiple low noise, single frequency master oscillator power amplifier (MOPA) lasers with a polarization-maintaining Yb-fiber amplifier will serve as the light sources for the LISA observatory. The NASA Goddard Space Flight Center (GSFC)is currently developing the laser transmitters for this project. The LISA lasers will carry radio frequency (RF)sidebands for exchanging reference RF clock information between spacecrafts. Excess phase noise, especially carrier-sideband differential phase noise added to the modulation side band by the phase modulator and the fiber amplifier, becomes a concern. In the gravitational wave frequency ranges, leading sources of this RF “differential” phase noise can be both intrinsic and extrinsic. Examples of intrinsic sources include thermal load on the active fiber, thermo-mechanical induced birefringence, and nonlinearities in the various passive and active fibers. Extrinsic sources can include external temperature fluctuations and infrasonic mechanical strain or vibrations. These noise spectra usually include both white and pink (1/f) thermal noise contributions. This work investigates the physical origins and impact of these sources of RF phase noise, and their characteristic spectra and management will be discussed.

Laser Interferometer Space Antenna↗

NASA NTRS2002

Fiber-Optic Pressure Sensor With Dynamic Demodulation Developed

Researchers at the NASA Glenn Research Center developed in-house a method to detect pressure fluctuations using a fiber-optic sensor and dynamic signal processing. This work was in support of the Intelligent Systems Controls and Operations project under NASA's Information Technology Base Research Program. We constructed an optical pressure sensor by attaching a fiber-optic Bragg grating to a flexible membrane and then adhering the membrane to one end of a small cylinder. The other end of the cylinder was left open and exposed to pressure variations from a pulsed air jet. These pressure variations flexed the membrane, inducing a strain in the fiber-optic grating. This strain was read out optically with a dynamic spectrometer to record changes in the wavelength of light reflected from the grating. The dynamic spectrometer was built in-house to detect very small wavelength shifts induced by the pressure fluctuations. The spectrometer is an unbalanced interferometer specifically designed for maximum sensitivity to wavelength shifts. An optimum pathlength difference, which was determined empirically, resulted in a 14-percent sensitivity improvement over theoretically predicted path-length differences. This difference is suspected to be from uncertainty about the spectral power difference of the signal reflected from the Bragg grating. The figure shows the output of the dynamic spectrometer as the sensor was exposed to a nominally 2-kPa peak-to-peak square-wave pressure fluctuation. Good tracking, sensitivity, and signal-to-noise ratios are evident even though the sensor was constructed as a proof-of-concept and was not optimized in any way. Therefore the fiber-optic Bragg grating, which is normally considered a good candidate as a strain or temperature sensor, also has been shown to be a good candidate for a dynamic pressure sensor.

Lekki, John D.↗

DOE OSTI2022

Strong increase in ultrasound attenuation below T c in Sr 2 RuO 4 : Possible evidence for domains

Recent experiments suggest that Sr 2 RuO 4 has a two-component superconducting order parameter (OP). A two-component OP has multiple degrees of freedom in the superconducting state that can result in low-energy collective modes or the formation of domain walls—a possibility that would explain a number of experimental observations including the smallness of the signature of time reversal symmetry breaking at T c and telegraph noise in critical current experiments. We use resonant ultrasound spectroscopy to perform ultrasound attenuation measurements across the superconducting T c of Sr 2 RuO 4 . We find that compressional sound attenuation increases by a factor of 7 immediately below T c , in sharp contrast with what is found in both conventional (s-wave) and high-T c (d-wave) superconductors. Our observations are most consistent with the presence of domain walls that separate different configurations of the superconducting OP. Here, the fact that we only observe an increase in sound attenuation for compressional strains, and not for shear strains, suggests an inhomogeneous superconducting state formed of two distinct, accidentally degenerate superconducting OPs that are not related to each other by symmetry. Whatever the mechanism, a factor of 7 increase in sound attenuation is a singular characteristic that must be reconciled with any potential theory of superconductivity in Sr 2 RuO 4 .

36 MATERIALS SCIENCE↗

NASA NTRS1980

Generalized Grueneisen tensor from solid nonlinearity parameters

Anharmonic effects in solids are often described in terms of generalized Grueneisen parameters which measure the strain dependence of the lattice vibrational frequencies. The relationship between these parameters and the solid nonlinearity parameters measured directly in ultrasonic harmonic generation experiments is derived using an approach valid for normal-mode elastic wave propagation in any crystalline direction. The resulting generalized Grueneisen parameters are purely isentropic in contrast to the Brugger-Grueneisen parameters which are of a mixed thermodynamic state. Experimental data comparing the isentropic generalized Grueneisen parameters and the Brugger-Grueneisen parameters are presented.

Cantrell, J. H., Jr.↗

DOE OSTI2022

In situ detection and characterization of alkali-silica reaction damage in concrete using contactless ultrasonic wavefield imaging

Here we present work to characterize cracking damage in concrete caused by alkali-silica reactivity distress. We apply contactless ultrasonic scan inspection, exploiting Rayleigh wave scattering from concrete inhomogeneities. The scanning system utilizes a multi-channel MEMS sensor array to collect ultrasonic wavefield data from concrete subjected to ASR-promoting environments. The location and extent of ASR damage are established by internal expansion measurements from embedded strain gauges, scanning electron microscope images of cored samples, and expansion measurements from companion samples. A wavefield data processing method extracts oscillatory fields from the ultrasonic wavefield data to detect distinct zones of ASR damage. A damage index is proposed to further characterize the extent of ASR damage. The results confirm the feasibility and accuracy of the approach to characterize ASR damage in concrete. The fully contactless ultrasonic scanning measurement system does not require separate material samples and enables in situ characterization of ASR damage within concrete structures.

36 MATERIALS SCIENCE↗

NASA NTRS2019

Directional limits on persistent gravitational waves using data from Advanced LIGO’s first two observing runs

We perform an unmodeled search for persistent, directional gravitational wave (GW) sources using data from the first and second observing runs of Advanced LIGO. We do not find evidence for any GW signals. We place limits on the broadband GW flux emitted at 25 Hz from point sources with a power law spectrum at F(α;Θ) < (0.05–25) × 10^(−8) erg/sq. cmsHz and the (normalized) energy density spectrum in GWs at 25 Hz from extended sources at Ω(α)(Θ) < (0.19–2.89) × 10^(−8) per sr where α is the spectral index of the energy density spectrum. These represent improvements of 2.5–3× over previous limits. We also consider point sources emitting GWs at a single frequency, targeting the directions of Sco X-1, SN 1987A, and the Galactic center. The best upper limits on the strain amplitude of a potential source in these three directions range from h(0) < (3.6–4.7) × 10^(−25), 1.5× better than previous limits set with the same analysis method. We also report on a marginally significant outlier at 36.06 Hz. This outlier is not consistent with a persistent gravitational-wave source as its significance diminishes when combining all of the available data.

B. P. Abbott↗