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At least 361 records · Page 20
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Non-Interference of Lunar Activities

As dozens of countries and private sector companies have expressed interest in establishing lunar operations by the end of the decade, including many in the South Pole region, it will be critical to determine how to deconflict lunar activities. Although lunar interference concerns have been broadly identified, and deconfliction has been identified as an area of further work in Section 11 of the Artemis Accords, there is not broad consensus in the lunar scientific or technical community on key questions such as how to identify relevant sites, the extent of protection needed, or mechanisms for mitigation. This paper seeks feedback from the scientific and technical community to determine the breadth of interference concerns and clarify community usage of the terms “interference”, “contamination”, and “deconfliction”. The paper proposes a framework for further deconfliction activity.

Lunar↗
NASA NTRSDate not supplied

Non-Interference of Lunar Activities

As dozens of countries and private sector companies have expressed interest in establishing lunar operations by the end of the decade, including many in the South Pole region, it will be critical to determine how to deconflict lunar activities. Although lunar interference concerns have been broadly identified, and deconfliction has been identified as an area of further work in Section 11 of the Artemis Accords, there is not broad consensus in the lunar scientific or technical community on key questions such as how to identify relevant sites, the extent of protection needed, or mechanisms for mitigation. This paper seeks feedback from the scientific and technical community to determine the breadth of interference concerns and clarify community usage of the terms “interference”, “contamination”, and “deconfliction”. The paper proposes a framework for further deconfliction activity.

Lunar↗
DOE OSTI2019

Spectral notch interference mitigation for stretch processing synthetic aperture radar

Various technologies for mitigating interference in stretch-processed SAR imagery are described herein. Stretch-processed SAR data is received at a computing device. The stretch-processed (or deramped) SAR data is then reramped, thereby removing frequency-variant components of narrowband interference signals in the deramped data. A frequency-domain transform is executed over the reramped data to generate a spectral characteristic of the reramped data. A spectral notch filter is applied to frequency bands corresponding to the peaks of the spectral characteristic in order to filter out the narrowband interference signals. An inverse frequency-domain transform can then be executed over the filtered spectral characteristic to return to a phase-history representation of the SAR data. The phase history resulting from the inverse frequency-domain transform is a ramped phase history, which can then be deramped prior to use in connection with generating images of the scanned scene.

Musgrove, Cameron↗
DOE OSTI2019

CORROSION RESISTANCE OF LASER-INTERFERENCE STRUCTURED ALUMINUM ALLOY 2024 COATED WITH MIL-PRF-85582 PRIMER

The use of aluminum alloys in aerospace industry requires more effective and reliable joining techniques. The lubricant contaminants from prior rolling operations affect surface energies and the quality of coating adhe-sion and adhesive bonded joints. In this study, a new laser-based technique is investigated as a surface treatment for coating applications. The laser interference power profile was created by splitting the beam and guiding both beams towards the specimen and overlapping them on the specimen surface, creating a line-interference pattern on the specimen surface. The laser-interference structuring (LIS) was used without any chemical treatments, such as those in chemical conversion coating (CCC) and sulfuric acid anodizing (SAA), which is a much simpler process than those chemical-based. To assess the effect of LIS on corrosion re-sistance of coating, Al 2024 panels prepared by LIS, CCC and SAA were coated with MIL-PRF-85582, Type I, Class N primer and exposed to salt spray environment according to ASTM B117. The exposure is currently in progress and the corrosion attack on the coated panels will be evaluated by the degree of blister formation and rust creepage.

Sabau, Adrian↗
DOE OSTI2026

Investigating Interference Term in DUNE And SBND Neutrino Interactions with ACHILLES

Understanding neutrino-nucleus interactions is critical for conducting precise neutrino oscillation ex- periments. However, uncertainties in neutrino-nucleus cross section measurements and our incomplete understanding of nuclear effects remain a significant challenge in neutrino physics. In this paper, we investigate contributions from quantum interference between one-body and two-body interactions in charged-current quasi-elastic (CCQE) neutrino scattering amplitudes, using the ACHILLES event gen- erator. Simulations are performed using muon neutrino flux from Fermilab’s Booster Neutrino Beam (BNB), as well as Long-Baseline Neutrino Facility (LBNF) flux. We observe the neutrino flux interact- ing with Argon nuclei as detected by the Short Baseline Near Detector (SBND) and DUNE Near Detector (DUNE-ND), both Liquid Argon Time Projection Chambers (LArTPC). We focus on one muon and one proton final states with cascade interactions. We analyze multiple experimental observables including outgoing kinematic variables, energy-momentum transfer variables, and Transverse Kinematic Imbalance (TKI) variables. In this study, we also investigate the effects of PRISM (a method of sampling flux from multiple off-axis angles which creates different neutrino energy spectra). We find that the ratio of in- terference to quasi-elastic contributions gives a non-flat distribution across a 0-3.5 GeV energy range, indicating that effects of interference vary with the neutrino energy sampled. Our ultimate goal is to reduce systematic uncertainties from neutrino interactions when conducting oscillation experiments by working to disentangle the effects of quantum interference from the quasi-elastic signature.

Serumaga, Peera [Fermilab; UC, San Diego] (ORCID:0↗
DOE OSTI2015

Polyatomic interferences on high precision uranium isotope ratio measurements by MC-ICP-MS: Applications to environmental sampling for nuclear safeguards

Modern mass spectrometry and separation techniques have made measurement of major uranium isotope ratios a routine task; however accurate and precise measurement of the minor uranium isotopes remains a challenge as sample size decreases. One particular challenge is the presence of isobaric interferences and their impact on the accuracy of minor isotope 234 U and 236 U measurements. Furthermore, we present techniques used for routine U isotopic analysis of environmental nuclear safeguards samples and evaluate polyatomic interferences that negatively impact accuracy as well as methods to mitigate their impacts.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Interference fringe (IF) technique for droplet contact angle and thickness measurements: Ultralow contact angle and nanoscale thickness measurement

Recently, reflection interference fringe (RIF) and transmission fringe (TIF) techniques have been introduced to investigate the origin of far-field interference fringe (IF) formation and to determine a droplet's contact angle and thickness by measuring the fringe radius. In this study, characteristics of the IF technique are analyzed based on the RIF and TIF by varying the schematics, such as configuration (transmission/reflection), the droplet's side (left-hand side/right-hand side), and the substrate types (flat/prism). The analysis also investigates the refraction effect at the droplet edge and the maximum incidence and contact angles. The schematic variation shows that the widest contact angle range can be measured in a transmission configuration with droplet's right-hand side, and that the fringe radius decreases with incidence angles on a prism substrate, consistent with the recent observation. Refraction at the droplet edge causes the fringe radius to increase or decrease depending on the degree of refraction. Based on the characteristics study, it is revealed that the IF technique can determine nanometer-scale thicknesses below 100 nm on droplets, corresponding to ultra-small contact angles of less than 0.01°, with an extended working distance of 3000 mm and an optimized incidence angle, assuming a spherical profile. This finding is significant, as it demonstrates that the nanoscale thickness can be determined in situ under ambient conditions using a simple optical configuration, without requiring a sophisticated setup, such as a microscope. It is anticipated that the IF technique can be combined with other nanoscale thickness measurement techniques to enhance its measurement reliability.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Investigation of Mechanical and Electromagnetic Interference Shielding Properties of Nickel–CFRP Textile Composites

The most common materials used for electromagnetic interference shielding are metals and their alloys. However, those materials are heavy and highly reflective. In order to eliminate or reduce the intensity of wave radiation in their working environment, lightweight materials that have interference shielding properties are needed. In this paper, nickel wire mesh yarns (warps) were woven into carbon fibers-reinforced plastic yarns (wefts) to produce metal–carbon textile composite materials. The plain weave and 2/2 twill weave techniques were used, and the woven fabrics were laminated to manufacture experimental test samples. The nickel, which has high magnetic permeability and good electric conductivity, and carbon fibers, which have good electrical, thermal and mechanical properties, were used together to achieve the desired properties. The shielding effectiveness of each sample was investigated using a network analyzer connected with coaxial transmission line test in accordance with ASTM 4935-99 standard, with the frequencies ranging from 500 MHz to 1.5 GHz. Here, the plain weave structure showed higher shielding effectiveness than twill weave. The absorption losses for both materials were relatively greater than reflection losses. In reference to the orientation of wire mesh yarns about the loading axis, the tensile strengths in the transversal direction were 19.04 and 16.34% higher than the tensile strengths in longitudinal direction for plain weave and twill weave, respectively. The fractography analysis with SEM showed a ductile fracture of wire mesh and brittle fracture of epoxy matrix and carbon fibers.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Dynamic modeling studies of basin-scale pressure interference and CO 2 plume evolution in multi-well geologic CO 2 storage

This research employs numerical modeling to analyze how CO 2 plumes and pressure fronts evolve when CO 2 is injected into a single storage formation from multiple projects located in proximity. Here, this analysis also evaluates the extent to which injection well spacing alleviates pressure buildup in the absence of active pressure management tactics. The simulation approach was based on a single, homogenous saline aquifer in which CO 2 injection occurs under a one-injector baseline case and several multi-well cases where well spacing varies. Analysis results show that the extent of pressure buildup is in the range of tens or a few hundreds of kilometers and contingent upon the defining pressure buildup demarcating the front edge. For the geological setting evaluated in this paper, our analysis suggests that without active basin pressure management strategies, commercial-scale projects would likely need to be sited far apart to avoid pressure interference from one another. Analysis results show the radius of CO 2 plume varies approximately from 2 to 3 km from injection wells (each injecting 1 Mt/year for 30 years) depending on cases and modeling parameters assumed. Given the pressure interference, this paper thus draws attention to the importance of greater coordination among storage operators and regulatory stakeholders. Because this analysis assumes a very specific geologic setting, this exploratory analysis bears further investigations across other geologic scenarios.

42 ENGINEERING↗
DOE OSTI2020

Laser-interference pulse number dependence of surface chemistry and sub-surface microstructure of AA2024-T3 alloy

The laser-based treatment of a metal surface is an intrinsically non-chemical technique that can alter both the topology and chemistry of surfaces. A laser-based treatment for coating and joining applications can offer alternative surface preparations to the chemically-based surface preparation techniques, which are subject to severe environmental protection and hazardous-waste management considerations. In this study, the surface chemistry and sub-surface microstructural changes are investigated for a novel surface processing method using laser interferometry produced by two beams of a pulsed Nd:YAG laser. The two-beam laser-interference allowed the structuring of the surface at length scales much less than that of the laser beam spot. Surface chemistry changes in the oxide layer of AA 2024-T3 aluminum alloy rolled sheet due to laser processing were investigated using x-ray photoelectron spectroscopy (XPS). Near surface microstructural changes have been investigated with scanning electron microscopy and energy dispersive x-ray spectroscopy (SEM/EDS), and scanning transmission electron microscopy (STEM) as a function of number of interfering laser shots. SEM microstructure pictures of the top surface shows the minimization of surface defects, as all of the sharp features from a rolled sheet surface were smoothed by laser-structuring. STEM images indicate that the laser-interference processing reduced the formation of CuMn-rich precipitates over a 500–800 nm depth from the top surface. XPS data indicated that the Al oxide layer is modified compared to that of the baseline specimen and that the oxide thickness increases with the number of shots per spot. Finally, the additional thicker oxide on Al alloys is expected to increase the corrosion resistance of the coated Al 2024.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Harnessing Quantum Interference in Molecular Dielectric Materials

We investigate the relationship between dielectric response and charge transport in molecule-based materials operating in the quantum coherent regime. We find that quantum interference affects these observables differently, for instance, allowing current passing through certain materials to be reduced by orders of magnitude without affecting dielectric behavior (or band gap). As an example, we utilize ab initio electronic structure theory to calculate conductance and dielectric constants of cross-conjugated anthraquinone (AQ)-based and linearly conjugated anthracene (AC)-based materials. In spite of having nearly equal fundamental gaps, electrode bonding configurations, and molecular dimensions, we find a ~1.7 order of magnitude (~50-fold) reduction in the conductance of the AQ-based material relative to the AC-based material, a value in close agreement with recent measurements, while the calculated dielectric constants of both materials are nearly identical. From these results, we propose two molecular materials in which quantum interference is used to reduce leakage currents across a ~25 Å monolayer gap with dielectric constants larger than 4.5.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Effects of electron interference on temperature dependent transport properties of two dimensional electron gas at MgZnO/ZnO interfaces

We report the effects of electron interference on temperature dependent transport properties of two dimensional electron gas (2DEG) confined at the interface in polycrystalline MgZnO/ZnO heterostructures grown by pulsed laser deposition on c-alumina substrates. On increasing Mg concentration in the MgZnO layer, the sheet electron concentration was found to increase and the sheet resistance was found to decrease. In addition, the electron concentration and mobility were almost temperature independent in the range from 4.2 to 300 K, indicating the formation of 2DEG at the interface. The temperature dependent resistivity measurements showed a negative temperature coefficient of resistivity at low temperatures together with negative magnetoresistance. These were found to be caused by electron interference effects, and the experimental data could be explained using the models of quantum corrections to conductivity.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

Interference with a quantum dot single-photon source and a laser at telecom wavelength

The interference of photons emitted by dissimilar sources is an essential requirement for a wide range of photonic quantum information applications. Many of these applications are in quantum communications and need to operate at standard telecommunication wavelengths to minimize the impact of photon losses and be compatible with existing infrastructure. Here, we demonstrate for the first time the quantum interference of telecom-wavelength photons from an InAs/GaAs quantum dot single-photon source and a laser; an important step towards such applications. The results are in good agreement with a theoretical model, indicating a high degree of indistinguishability for the interfering photons.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

New edge magnetoplasmon interference like photovoltage oscillations and their amplitude enhancement in the presence of an antidot lattice

We present new photovoltage oscillation in a pure two dimensional electron gas (2DEG) and in the presence of circular or semicircular antidot lattices. Results were interpreted as EMPs-like photovoltage oscillations. We observed and explained the photovoltage oscillation amplitude enhancement in the presence of an antidot lattice with regard to the pure 2DEG. The microwave frequency excitation range is 139 – 350 GHz. The cyclotron and magnetoplasmon resonances take place in the magnetic field range 0.4 – 0.8 T. This original experimental condition allows edge magnetoplasmons EMPs interference like observation at low magnetic field, typically B < B{sub c} where B{sub c} is the magnetic field at which the cyclotron resonance takes place. The different oscillation periods observed and their microwave frequency dependence were discussed. For 139 and 158 GHz microwave excitation frequencies, a unique EMPs-like interference period was found in the presence of antidots whereas two periods were extracted for 295 or 350 GHz. An explanation of this effect is given taking account of strong electron interaction with antidot at low magnetic field. Indeed, electrons involved in EMPs like phenomenon interact strongly with antidots when electron cyclotron orbits are larger than or comparable to the antidot diameter.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Ultra-small and broadband polarization splitters based on double-slit interference

An ultra-small and broadband polarization splitter is numerically and experimentally demonstrated based on the double-slit interference in a polymer-film-coated double-slit structure. The hybrid slab waveguide (air-polymer-Au) supports both the transverse-magnetic and transverse-electric modes. The incident beam from the back side can excite these two guided modes of orthogonally polarized states in the hybrid structure. By exploiting the difference slit widths and the large mode birefringence, these two guided modes propagate to the opposite directions along the front metal surface. Moreover, the short interference length broadens the operation bandwidth. Experimentally, a polarization splitter with a lateral dimension of only about 1.6 μm and an operation bandwidth of 50 nm is realized. By designing the double-slit structure in a hybrid strip waveguide, the device dimension can be significant downscaled to about 0.3 × 1.3 μm{sup 2}. Such an ultra-small and broadband polarization splitter may find important applications in the integrated photonic circuits.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

Landau-Zener-Stückelberg-Majorana interference in a 3D transmon driven by a chirped microwave

By driving a 3D transmon with microwave fields, we generate an effective avoided energy-level crossing. Then we chirp microwave frequency, which is equivalent to driving the system through the avoided energy-level crossing by sweeping the avoided crossing. A double-passage chirp produces Landau-Zener-Stückelberg-Majorana (LZSM) interference that agree well with the numerical results, especially with the initial state being an eigen-energy state in the center of an avoided level crossing. A time-resolved state tomography measurement is performed in the evolution of LZSM interference, showing an experimental evidence for the dynamical evolution of quantum state. Our method is fully applicable to other quantum systems that contain no intrinsic avoided level crossing, providing an alternative approach for quantum control and quantum simulation.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

Effects of phase singularity in the interference of two laser fields with a wide spectrum

The interference of laser beams with a wide spectrum is studied theoretically and numerically. It is shown that in the cross section of such intersecting beams in a small vicinity of zero of the complex mutual coherence function, the change in the argument of the slow amplitude of this function corresponds to the phase singularity. An approximate analytical representation of the mutual coherence function in the vicinity of the singularity point is given. It is found that an average ‘funnel’ diameter of the modulus of the mutual coherence function that arises in the singularity region does not depend on the intensity of the light beams and remains constant when the longitudinal coordinate changes. The emergence of phase dislocations in the interference pattern is established. (laser beams)

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

Design and analysis of logic NOR, NAND and XNOR gates based on interference effect

We have developed and analysed logic NOR, NAND and XNOR gates based on two dimensional (2D) photonic crystals at a wavelength of 1.55 μm. The interference and self-collimation effects are used to design logic gates, which control the output by adjusting the phase difference to achieve constructive or destructive interference. The splitter is a line defect of the photonic crystal with a row of periodically arranged air rods. The radius of the defect rods depends on the function of the logic element. The use of these logic gates can reduce the size of logic devices. (optical logic elements)

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗