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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 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Improved optical standing-wave beam splitters for dilute Bose–Einstein condensates

Bose–Einstein condensate (BEC)-based atom interferometry exploits low temperatures and long coherence lengths to facilitate high-precision measurements. Progress in atom interferometry promises improvements in navigational devices like gyroscopes and accelerometers, as well as applications in fundamental physics such as accurate determination of physical constants. Previous work demonstrates that beam splitters and mirrors for coherent manipulation of dilute BEC momentum in atom interferometers can be implemented with sequences of non-resonant standing-wave light pulses. While previous work focuses on the optimization of the optical pulses’ amplitude and duration to produce high-order momentum states with high fidelity, we explore how varying the shape of the optical pulses affects optimal beam-splitter performance, as well as the effect of pulse shape on the sensitivity of optimized parameters in achieving high fidelity in high-momentum states. Here, in simulations of two-pulse beam splitters utilizing optimized square, triangle, and sinc-squared pulse shapes applied to dilute BECs, we, in some cases, reduce parameter sensitivity by an order of magnitude while maintaining fidelity.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2022

Current advances on Talbot–Lau x-ray imaging diagnostics for high energy density experiments (invited)

Talbot–Lau x-ray interferometry is a refraction-based diagnostic that can map electron density gradients through phase-contrast methods. The Talbot–Lau x-ray deflectometry (TXD) diagnostics have been deployed in several high energy density experiments. To improve diagnostic performance, a monochromatic TXD was implemented on the Multi-Tera Watt (MTW) laser using 8 keV multilayer mirrors (Δθ/θ = 4.5%-5.6%). Copper foil and wire targets were irradiated at 10 14 –10 15 W/cm 2 . Laser pulse length (~10 to 80 ps) and backlighter target configurations were explored in the context of Moiré fringe contrast and spatial resolution. Foil and wire targets delivered increased contrast <30%. The best spatial resolution (<6 μm) was measured for foils irradiated 80° from the surface. Further TXD diagnostic capability enhancement was achieved through the development of advanced data postprocessing tools. The Talbot Interferometry Analysis (TIA) code enabled x-ray refraction measurements from the MTW monochromatic TXD. Additionally, phase, attenuation, and dark-field maps of an ablating x-pinch load were retrieved through TXD. The images show a dense wire core of ~60 μm diameter surrounded by low-density material of ~40 μm thickness with an outer diameter ratio of ~2.3. Attenuation at 8 keV was measured at ~20% for the dense core and ~10% for the low-density material. Instrumental and experimental limitations for monochromatic TXD diagnostics are presented. Enhanced postprocessing capabilities enabled by TIA are demonstrated in the context of high-intensity laser and pulsed power experimental data analysis. Significant advances in TXD diagnostic capabilities are presented. Furthermore, these results inform future diagnostic technique upgrades that will improve the accuracy of plasma characterization through TXD.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2021

Laser scattering by submicron droplets formed during the electrical explosion of thin metal wires

Abstract This paper presents the results of studying dispersed media formation during the electrical explosion of thin metal wires in vacuum by using low-current generators (~1–10 kA). Particular attention is paid to the analysis of the composition and structure of the corresponding explosion products as well as to the problem of their visualization using simultaneous laser interferometry and shadow imaging at two wavelengths (1.064 µ m and 0.532 µ m). Our findings indicate the important role in the visualization of the explosion products that belongs to multiple scattering by submicron droplets of dense condensed matter, which are mixed with metal vapor. The hypothesis on the existence of submicron droplets in the products of exploding metal wires correlates with the results obtained by soft x-ray radiography combined with a laser probing technique. Taking into account the multiple scattering by submicron droplets, it is possible to significantly clarify the parameters of the explosion products visualized via laser probing techniques as well as to gain a deeper insight into the physics behind the electrical wire explosion.

Physics↗
DOE OSTI2024

Requirements for probing chiral Casimir-Polder forces in a molecular Talbot-Lau interferometer

We theoretically investigate the influence of chiral Casimir-Polder (CP) forces in Talbot-Lau interferometry, based on three nanomechanical gratings. We study scenarios where the second grating is either directly written into a chiral material or where the nanomask is coated with chiral substances. We show requirements for probing enantiospecific effects in matter-wave interferometry in the transmission signal and the interference fringe visibility, which depend on the de Broglie wavelength and the molecular chirality. The proposed setup is particularly sensitive to CP forces in the nonretarded regime where chiral effects can be comparable in magnitude to their electric and magnetic counterparts. While the first and third gratings do not change the phase of the matter wave, applying a coating of chiral substances to them enhances the instrument's chiral selectivity. Published by the American Physical Society 2024

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2025

Measurements of source emittance and beam coherence properties of the upgraded Advanced Photon Source

The Advanced Photon Source (APS) has been upgraded with a multi-bend achromat lattice, achieving significantly reduced electron beam emittance and enhanced X-ray coherence. Precise characterization of these properties is essential for optimizing beamline performance and enabling new experiments that take full advantage of the upgraded source. We report on measurements of source size and transverse coherence properties using grating interferometry at two beamlines: the APS 3-ID-B undulator beamline and the 1-BM-B bending magnet beamline. The results confirm the world-record horizontal emittance of the upgraded APS below 30 pm rad and validate the theoretical design parameters. We further investigate the impact of optical aberrations and mechanical vibrations at the 12-ID-C beamline on coherence preservation. These measurements establish a benchmark for future beamline enhancements and demonstrate the effectiveness of grating interferometry for high-precision beam characterization. Our findings provide critical insights into synchrotron beam dynamics, coherence degradation mechanisms, and strategies for optimizing beamline X-ray optics at next-generation light sources.

Advanced Photon Source↗
DOE OSTI2020

Optical Response of Soda-Lime Glass Shocked to 14 GPa

To investigate the potential use of soda-lime glass (SLG) as an optical window in shock wave experiments, laser interferometry (VISAR) was used to determine the window correction and the refractive index in SLG samples subjected to plane shock wave compression. Symmetric plate impact experiments were conducted at peak stresses varying between 4 and 14 GPa and laser interferometry ($λ_0$ = 532$\textit {nm}$ wavelength) measurements were used to monitor the particle velocity histories at the impact surface. The higher stress experiments displayed a constant state prior to stress unloading. In contrast, the lower stress experiments (4.3 and 7.8 GPa) displayed an initial constant state followed by weakly time-dependent response prior to stress unloading. Because the actual particle velocities were independently known from the projectile velocity measurements, the window correction factor and the refractive index changes were determined over the stress range examined. Above 7.5 GPa, our window correction and refractive index results show significant differences with previously published data for the same material. Potential reasons for these differences are indicated.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Fundamental physics opportunities with future ground-based mm/sub-mm VLBI arrays

The Event Horizon Telescope (EHT) Collaboration recently published the first images of the supermassive black holes in the cores of the Messier 87 and Milky Way galaxies. These observations have provided a new means to study supermassive black holes and probe physical processes occurring in the strong-field regime. We review the prospects of future observations and theoretical studies of supermassive black hole systems. Current ground-based very-long-baseline interferometry (VLBI) arrays like the EHT and proposed future extensions like the next-generation Event Horizon Telescope will greatly enhance the capabilities of black-hole imaging interferometry. These enhancements will open up several previously inaccessible avenues of investigation, thereby providing important new insights into the properties of supermassive black holes and their environments. This review describes the current state of knowledge for five key science cases, summarising the unique challenges and opportunities for fundamental physics investigations that future mm/sub-mm VLBI developments will enable.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Slow Electron Holes in the Earth's Magnetosheath

Here, we present a statistical analysis of electrostatic solitary waves observed aboard Magnetospheric Multiscale spacecraft in the Earth's magnetosheath. Applying single-spacecraft interferometry to several hundred solitary waves collected in about 2-minute interval, we show that almost all of them have the electrostatic potential of positive polarity and propagate quasi-parallel to the local magnetic field with plasma frame velocities of the order of 100 km/s. The solitary waves have typical parallel half-widths from 10 to 100 m that is between 1 and 10 Debye lengths and typical amplitudes of the electrostatic potential from 10 to 200 mV that is between 0.01% and 1% of local electron temperature. The solitary waves are associated with quasi-Maxwellian ion velocity distribution functions, and their plasma frame velocities are comparable with ion thermal speed and well below electron thermal speed. We argue that the solitary waves of positive polarity are slow electron holes and estimate the time scale of their acceleration, which occurs due to interaction with ions, to be of the order of one second. The observation of slow electron holes indicates that their lifetime was shorter than the acceleration time scale. We argue that multi-spacecraft interferometry applied previously to these solitary waves is not applicable because of their too-short spatial scales. The source of the slow electron holes and the role in electron-ion energy exchange remain to be established.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2026

Early-stage uranium-hydrogen corrosion kinetics and mechanism

Research into the early-stage uranium-hydrogen degradation mechanism lacks unified interpretation and understanding due to inadequate temporal and spatial characterization resolution required to unify reaction observations. In this study, white-light interferometry was adapted to characterize the uranium-hydrogen reaction at a temperature of 50 °C and hydrogen pressure of 13.8 kPa. The uranium surface remained unchanged for 62 min during the hydride induction period before the first hydride blister appeared. This blister was monitored from induction through critical spallation and UH₃ powder release during rapid surface hydriding. The critical spallation dimensions measured for height, diameter, area, and perimeter of the first blister were 1.79 µm, 17.58 µm, 187.7 µm 2 and 59.79 µm. Hydriding growth kinetics were assessed by tracking the first hydride site over the reaction time. Analysis shows that the spall-front velocity of the hydride was changing at a rate of 0.91 µm/min which compares favorably with legacy Sievert’s experiments in literature. Total percentage of the surface area hydrided after 242 min was 42.7%, and post-characterization of the UH 3 powders shows both α-UH 3 and β-UH 3 . This work highlights the strength of characterizing the early-stage uranium-hydrogen reaction using white-light interferometry, but more importantly, unifying the understanding and mechanism of the uranium-hydrogen reaction kinetics.

Materials science↗
DOE OSTI2020

Electron plasma wave Thomson scattering on laboratory plasma jets

Plasma jets created from a 15 lm thick Al foil on a 1 MA pulsed power machine were studied using a new electron plasma wave (EPW) Thomson scattering system in conjunction with previously developed ion acoustic wave (IAW) Thomson scattering and interferometry. These diagnostics give multiple ways of measuring the electron temperature and density of the jet. Analysis of the EPW feature found the on-axis density of the jet to be between 5 X 10 18 and 1.4 X 10 19 cm -3 , which either matched or was higher than interferometry measurements. Outside of the jet, both of these diagnostics measured a density of 7 X 10 17 cm -3 . On one shot, the EPW spectral feature showed two pairs of peaks within a 250 lm scattering length on the edge of the jet, which shows that the boundary of the jet ~1 mm radius jet is 0.1 mm. While electron temperature measurements of the plasma jet are complicated by the probe beam producing inverse bremsstrahlung heating of the jet, comparison of the electron temperature measured between IAW and EPW Thomson scattering showed the EPW feature to imply significantly higher electron temperatures than the IAW feature (e.g., 160 eV vs 70 eV in one case). Various sources of this discrepancy (for example, density gradients, collisions, and a lag in ionization) and their impact on the plasma are discussed.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2020

Hugoniot states and optical response of soda lime glass shock compressed to 120 GPa

In contrast to relatively pure silica glass (fused silica-FS), commercial silica-rich glasses contain significant fractions of additional oxide components. In particular, soda-lime glass (SLG) consists of approximately 71% SiO 2 by weight, which raises the question: what is the effect of additional cations on the shock compression response of silica-rich glasses? To address this concern, plate impact experiments were conducted to determine the high-pressure Hugoniot states for shocked SLG (37 to 120 GPa) and compared with recently reported results on FS. Using laser interferometry, particle velocity profiles were measured at the impact surface and the SLG/LiF window interface. In all experiments, the transmitted profiles show a single shock wave, with no features indicative of a phase transformation. The Hugoniot states determined from the wave profiles are described well using a linear shock velocity–particle velocity relation. Interferometry measurements (using 1550-nm wavelength laser) at the impact surface show that SLG is transparent when shocked to 55 GPa, transparent for tens of nanoseconds after impact between 55 and 81 GPa, and opaque beyond 81 GPa. From impact surface measurements, a linear relationship between the apparent and true particle velocity was observed, resulting in a linear relationship between the refractive index (at 1550 nm) and density. At 120 GPa, the SLG density is nearly twice its ambient value, indicating that SLG can achieve highly dense amorphous states. When compared to FS, shocked SLG is much less compressible and likely does not transform to a crystalline phase. A plausible explanation for this difference is indicated.

58 GEOSCIENCES↗
DOE OSTI2025

Experimental study of high-energy single-pulse nanosecond discharges in pin-to-pin configuration

Single-pulse pin-to-pin nanosecond pulsed discharges in ambient air (gap distances of 3–7 mm) were investigated at high pulse energies (∼20–30 mJ deposited energy per 11 ns full width at half maximum pulse). A Michelson interferometry setup (532 nm continuous-wave laser) was employed to record time-resolved interferograms of the discharge, enabling spatially resolved calculation of the electron number density. An intensified charge-coupled device camera was used to capture the spatiotemporal evolution of the discharge (streamer formation and spark channel development), and Coherent Anti-Stokes Raman Spectroscopy (CARS) was used to measure post-discharge N 2 vibrational temperatures. Discharge current and voltage were monitored with a back-current shunt. The discharge was initiated with simultaneous cathode-directed and anode-directed streamers that bridge the gap within ∼1 ns and form a luminous, filamentary plasma channel immediately after breakdown. Laser interferometry measurements showed peak electron number densities of the order of 10 1 7–10 18 cm −3 , occurring about 15–20 ns after pulse arrival at the discharge gap. Shorter gap discharges yielded higher peak electron densities, consistent with the higher energy density in the smaller gaps. Spatially, the electron density was highest near the electrodes and decreased toward the midgap region, with 5 and 7 mm gaps exhibiting a pronounced drop in the central channel. CARS indicated initial vibrational temperatures of approximately 4000–6000 K in the spark core of ∼50 ns after the discharge onset, decaying on a ∼500 ns timescale as the plasma cooled and recombined.

Coherent anti-Stokes Raman spectroscopy↗
DOE OSTI2026

Multi-diagnostic characterization of laser-produced tin plasmas for EUV lithography

We present a comprehensive characterization of laser-produced tin (Sn) plasmas relevant to extreme ultraviolet (EUV) lithography using a multi-diagnostic suite integrated into the new experimental platform, “SparkLight.” Tin plasmas are generated by irradiating a continuously moving tin-coated wire with laser pulses (1064 nm, 10 ns, up to 5.7 × 10 10 W/cm 2 ) and probed via coherent Thomson scattering, laser interferometry, and EUV emission spectroscopy. Thomson scattering measurements reveal electron temperatures and densities that decay with distance from the target. Densities derived from Thomson scattering are cross-validated against laser interferometry, showing excellent agreement. Correlating the results of these laser diagnostics with spatially resolved EUV spectroscopy suggests that the bulk of useful EUV emission originates within 150 μm of the target and is generated under suboptimal plasma conditions. This work demonstrates a practical integrated approach for plasma characterization in EUV source development.

Musikhin, S. [Princeton Plasma Physics Laboratory ↗
DOE OSTI2022

Fast wave interferometer for ion density measurement on DIII-D

=A fast wave interferometer (FWI), which can measure ion mass density, has been developed on DIII-D for its use on future fusion reactors, as well as for the study of ion behavior in current plasma devices. The frequency of the fast waves used for the FWI is around 60 MHz, and require antennas and coaxial cables or waveguides, which, unlike traditional mirror-based optical interferometers, are less susceptible to neutron/gamma-ray radiation and are relatively immune to impurity deposition and erosion as well as alignment issues. The bulk ion density evaluated using FWI show good agreement with that derived from CO 2 interferometry within about 15%. When the ion mass density measurement by FWI is combined with an electron density measurement from CO 2 interferometry, Z eff measurements are also enabled and are in agreement with those from visible Bremsstrahlung measurements. Additionally, large-bandwidth FWI measurements clearly resolve 10–100 kHz coherent modes and demonstrate its potential as a core fluctuation diagnostic, sensitive to both magnetic and ion density perturbations.

Instruments & Instrumentation↗
DOE OSTI2022

Novel light field imaging device with enhanced light collection for cold atom clouds

We present a light field imaging system that captures multiple views of an object with a single shot. The system is designed to maximize the total light collection by accepting a larger solid angle of light than a conventional lens with equivalent depth of field. This is achieved by populating a plane of virtual objects using mirrors and fully utilizing the available field of view and depth of field. Simulation results demonstrate that this design is capable of single-shot tomography of objects of size $\mathcal{O}$(1 mm 3 ), reconstructing the 3-dimensional (3D) distribution and features not accessible from any single view angle in isolation. In particular, for atom clouds used in atom interferometry experiments, the system can reconstruct 3D fringe patterns with size $\mathcal{O}$(100 μm). We also demonstrate this system with a 3D-printed prototype. The prototype is used to take images of $\mathcal{O}$(1 mm 3 ) sized objects, and 3D reconstruction algorithms running on a single-shot image successfully reconstruct $\mathcal{O}$(100 μm) internal features. The prototype also shows that the system can be built with 3D printing technology and hence can be deployed quickly and cost-effectively in experiments with needs for enhanced light collection or 3D reconstruction. Imaging of cold atom clouds in atom interferometry is a key application of this new type of imaging device where enhanced light collection, high depth of field, and 3D tomographic reconstruction can provide new handles to characterize the atom clouds.

47 OTHER INSTRUMENTATION↗
DOE OSTI2024

Saturating the one-axis twisting quantum Cramér-Rao bound with a total spin readout

We show that the lowest quantum Cramér-Rao bound achievable in interferometry with a one-axis twisted spin coherent state is saturated by the asymptotic method of moments error of a protocol that uses one call to the one-axis twisting, one call to time-reversed one-axis twisting, and a final total spin measurement (i.e., a twist-untwist protocol). The result is derived by first showing that the metrological phase diagram for one-axis twisting is asymptotically characterized by a single quantum Fisher information value N(N + 1)/2 for all times, then constructing a twist-untwist protocol having a method of moments error that saturates this value. The case of finite-range one-axis twisting is similarly analyzed, and a simple functional form for the metrological phase diagram is found in both the short-range and long-range interaction regimes. Numerical evidence suggests that the finite-range analogues of twist-untwist protocols can exhibit a method of moments error that asymptotically saturates the lowest quantum Cramér-Rao bound achievable in interferometry with finite-range one-axis twisted spin coherent states for all interaction times.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Source size measurement options for low-emittance light sources

Radiation-based techniques for measuring electron source sizes are widely used as emittance diagnostics at existing synchrotron sources. Three of these techniques, namely, pinhole imaging, double-slit interferometry, and a K-edge filter-based beam position and size monitor system (ps-BPM), are evaluated for measuring source sizes at low-emittance storage rings. Each technique is reviewed with a detailed system description, design optimization, and practical considerations targeted for small source sizes. Pinhole imaging has the simplest setup and gives the beam profile in both transverse dimensions but with limited resolution. Double-slit interferometry has the highest resolution but with a limited detectable size range. The ps-BPM system shows reasonable resolution for monitoring small source sizes and divergence and can give real-time information of the source position and angle. New facilities may consider an integrated system that combines some or all of these techniques.

43 PARTICLE ACCELERATORS↗
DOE OSTI2024

Achieving a near-ideal silicon crystal neutron interferometer using submicrometer fabrication techniques

Perfect-crystal neutron interferometry, which is analogous to Mach-Zehnder interferometry, uses Bragg diffraction to form interfering neutron paths. The measured phase shifts can be used to probe many types of interactions whether it be nuclear, electromagnetic, gravitational, or topological in nature. For a perfect-crystal interferometer to preserve coherence, the crystal must possess a high degree of dimensional tolerance as well as being relatively defect-free with minimal internal stresses. In the past, perfect-crystal neutron interferometers have been produced by a two-step process. First, a resin diamond wheel would be used to remove excess material and shape the interferometer. Afterword, the crystal would be etched to remove surface defects and elevate strains. This process has had limitations in terms of repeatability and in maximizing the final contrast, or fringe visibility, of the interferometer. We have tested various fabrication and post-fabrication techniques on a single perfect-crystal neutron interferometer and measured the interferometer's performance at each step. Here we report a robust, nonetching fabrication process with high final contrast. For the interferometer used in this work, we achieved contrasts of greater than 90% several times and ultimately finished with an interferometer that has 92% contrast and a uniform phase distribution. Published by the American Physical Society 2024

Huber, M. G. (ORCID:0000000237958445)↗