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Sample records for near-field coupled processes

  1. Panel discussion on near-field coupled processes with emphasis on performance assessment

    SciTech Connect

    Codell, R.B.; Baca, R.G.; Ahola, M.P.

    1996-04-01

    The presentations in this panel discussion involve the general topic of near-field coupled processes and postclosure performance assessment with an emphasis on rock mechanics. The potential impact of near-field rock mass deformation on repository performance was discussed, as well as topics including long term excavation deterioration, the performance of geologic seals, and coupled processes concerning rock mechanics in performance assessments.

  2. Modeled near-field environment porosity modifications due to coupled thermohydrologic and geochemical processes

    SciTech Connect

    Glassley, W. E.; Nitao, J. J.

    1998-10-30

    Heat deposited by waste packages in nuclear waste repositories can modify rock properties by instigating mineral dissolution and precipitation along hydrothermal flow pathways. Modeling this reactive transport requires coupling fluid flow to permeability changes resulting from dissolution and precipitation. Modification of the NUFT thermohydrologic (TH) code package to account for this coupling in a simplified geochemical system has been used to model the time- dependent change in porosity, permeability, matrix and fracture saturation, and temperature in the vicinity of waste-emplacement drifts, using conditions anticipated for the potential Yucca Mountain repository. The results show, within a few hundred years, dramatic porosity reduction approximately 10 m above emplacement drifts. Most of this reduction is attributed to deposition of solute load at the boiling front, although some of it also results from decreasing temperature along the flow path. The actual distribution of the nearly sealed region is sensitive to the time- dependent characteristics of the thermal load imposed on the environment and suggests that the geometry of the sealed region can be engineered by managing the waste-emplacement strategy.

  3. Near Field Environment Process Model Report

    SciTech Connect

    R.A. Wagner

    2000-11-14

    Waste emplacement and activities associated with construction of a repository system potentially will change environmental conditions within the repository system. These environmental changes principally result from heat generated by the decay of the radioactive waste, which elevates temperatures within the repository system. Elevated temperatures affect distribution of water, increase kinetic rates of geochemical processes, and cause stresses to change in magnitude and orientation from the stresses resulting from the overlying rock and from underground construction activities. The recognition of this evolving environment has been reflected in activities, studies and discussions generally associated with what has been termed the Near-Field Environment (NFE). The NFE interacts directly with waste packages and engineered barriers as well as potentially changing the fluid composition and flow conditions within the mountain. As such, the NFE defines the environment for assessing the performance of a potential Monitored Geologic Repository at Yucca Mountain, Nevada. The NFe evolves over time, and therefore is not amenable to direct characterization or measurement in the ambient system. Analysis or assessment of the NFE must rely upon projections based on tests and models that encompass the long-term processes of the evolution of this environment. This NFE Process Model Report (PMR) describes the analyses and modeling based on current understanding of the evolution of the near-field within the rock mass extending outward from the drift wall.

  4. Source near-field effects on HPM coupling

    SciTech Connect

    King, R.J.; Hudson, H.G.

    1988-08-01

    This report gives an overview of many of these issues and cites examples. It is part of an on-going effort to investigate all aspects of the phenomenology of HPM interactions with systems. Experimental results are given for near-field coupling into generic test systems. While we do not exhaustively answer all of these questions, certain trends are observed. From these, some general conclusions are drawn to guide the use of HPM simulators for testing full systems. 3 refs., 43 figs., 2 tabs.

  5. Nonadiabatic photodissociation process using an optical near field.

    PubMed

    Kawazoe, Tadashi; Kobayashi, Kiyoshi; Takubo, Satoru; Ohtsu, Motoichi

    2005-01-01

    We demonstrated the deposition of nanometric Zn dots using photodissociation with gas-phase diethylzinc and an optical near field under nonresonant conditions. To explain the experimental results, we proposed an exciton-phonon polariton model, and discuss the quantitative experimental dependence of the deposition rate on the optical power and photon energy based on photodissociation involving multiple-step excitation via molecular vibration modes. The physical basis of this process, which seems to violate the Franck-Condon principle, is the optically nonadiabatic excitation of the molecular vibration mode due to the steep spatial gradient of the optical near-field energy. PMID:15638622

  6. Near-field environment/processes working group summary

    SciTech Connect

    Murphy, W.M.

    1995-09-01

    This article is a summary of the proceedings of a group discussion which took place at the Workshop on the Role of Natural Analogs in Geologic Disposal of High-Level Nuclear Waste in San Antonio, Texas on July 22-25, 1991. The working group concentrated on the subject of the near-field environment to geologic repositories for high-level nuclear waste. The near-field environment may be affected by thermal perturbations from the waste, and by disturbances caused by the introduction of exotic materials during construction of the repository. This group also discussed the application of modelling of performance-related processes.

  7. Active control of near-field coupling in conductively coupled microelectromechanical system metamaterial devices

    NASA Astrophysics Data System (ADS)

    Pitchappa, Prakash; Manjappa, Manukumara; Ho, Chong Pei; Qian, You; Singh, Ranjan; Singh, Navab; Lee, Chengkuo

    2016-03-01

    We experimentally report a structurally reconfigurable metamaterial for active switching of near-field coupling in conductively coupled, orthogonally twisted split ring resonators (SRRs) operating in the terahertz spectral region. Out-of-plane reconfigurable microcantilevers integrated into the dark SRR geometry are used to provide active frequency tuning of dark SRR resonance. The geometrical parameters of individual SRRs are designed to have identical inductive-capacitive resonant frequency. This allows for the excitation of classical analogue of electromagnetically induced transparency (EIT) due to the strong conductive coupling between the SRRs. When the microcantilevers are curved up, the resonant frequency of dark SRR blue-shifts and the EIT peak is completely modulated while the SRRs are still conductively connected. EIT modulation contrast of ˜50% is experimentally achieved with actively switchable group delay of ˜2.5 ps. Electrical control, miniaturized size, and readily integrable fabrication process of the proposed structurally reconfigurable metamaterial make it an ideal candidate for the realization of various terahertz communication devices such as electrically controllable terahertz delay lines, buffers, and tunable data-rate channels.

  8. Thermodynamic coupling of heat and matter flows in near-field regions of nuclear waste repositories

    SciTech Connect

    Carnahan, C.L.

    1983-11-01

    In near-field regions of nuclear waste repositories, thermodynamically coupled flows of heat and matter can occur in addition to the independent flows in the presence of gradients of temperature, hydraulic potential, and composition. The following coupled effects can occur: thermal osmosis, thermal diffusion, chemical osmosis, thermal filtration, diffusion thermal effect, ultrafiltration, and coupled diffusion. Flows of heat and matter associated with these effects can modify the flows predictable from the direct effects, which are expressed by Fourier's law, Darcy's law, and Fick's law. The coupled effects can be treated quantitatively together with the direct effects by the methods of the thermodynamics of irreversible processes. The extent of departure of fully coupled flows from predictions based only on consideration of direct effects depends on the strengths of the gradients driving flows, and may be significant at early times in backfills and in near-field geologic environments of repositories. Approximate calculations using data from the literature and reasonable assumptions of repository conditions indicate that thermal-osmotic and chemical-osmotic flows of water in semipermeable backfills may exceed Darcian flows by two to three orders of magnitude, while flows of solutes may be reduced greatly by ultrafiltration and chemical osmosis, relative to the flows predicted by advection and diffusion alone. In permeable materials, thermal diffusion may contribute to solute flows to a smaller, but still significant, extent.

  9. Resonance hybridization and near field properties of strongly coupled plasmonic ring dimer-rod nanosystem

    SciTech Connect

    Koya, Alemayehu Nana; Ji, Boyu; Hao, Zuoqiang; Lin, Jingquan

    2015-09-21

    Combined effects of polarization, split gap, and rod width on the resonance hybridization and near field properties of strongly coupled gold dimer-rod nanosystem are comparatively investigated in the light of the constituent nanostructures. By aligning polarization of the incident light parallel to the long axis of the nanorod, introducing small split gaps to the dimer walls, and varying width of the nanorod, we have simultaneously achieved resonance mode coupling, huge near field enhancement, and prolonged plasmon lifetime. As a result of strong coupling between the nanostructures and due to an intense confinement of near fields at the split and dimer-rod gaps, the extinction spectrum of the coupled nanosystem shows an increase in intensity and blueshift in wavelength. Consequently, the near field lifespan of the split-nanosystem is prolonged in contrast to the constituent nanostructures and unsplit-nanosystem. On the other hand, for polarization of the light perpendicular to the long axis of the nanorod, the effect of split gap on the optical responses of the coupled nanosystem is found to be insignificant compared to the parallel polarization. These findings and such geometries suggest that coupling an array of metallic split-ring dimer with long nanorod can resolve the huge radiative loss problem of plasmonic waveguide. In addition, the Fano-like resonances and immense near field enhancements at the split and dimer-rod gaps imply the potentials of the nanosystem for practical applications in localized surface plasmon resonance spectroscopy and sensing.

  10. Near field fluid coupling between internal motion of the organ of Corti and the basilar membrane

    SciTech Connect

    Elliott, Stephen J.; Ni, Guangjian

    2015-12-31

    The pressure distribution in each of the fluid chambers of the cochlea can be decomposed into a 1D, or plane wave, component and a near field component, which decays rapidly away from the excitation point. The transverse motion of the basilar membrane, BM, for example, generates both a 1D pressure field, which couples into the slow wave, and a local near field pressure, proportional to the BM acceleration, that generates an added mass on the BM due to the fluid motion. When the organ of Corti, OC, undergoes internal motion, due for example to outer hair cell activity, this motion will not itself generate any 1D pressure if the OC is incompressible and the BM is constrained not to move volumetrically, and so will not directly couple into the slow wave. This motion will, however, generate a near field pressure, proportional to the OC acceleration, which will act on the OC and thus increases its effective mass. The near field pressure due to this OC motion will also act on the BM, generating a force on the BM proportional to the acceleration of the OC, and thus create a “coupling mass” effect. By reciprocity, this coupling mass is the same as that acting on the OC due to the motion of the BM. This near field fluid coupling is initially observed in a finite element model of a slice of the cochlea. These simulations suggest a simple analytical formulation for the fluid coupling, using higher order beam modes across the width of the cochlear partition. It is well known that the added mass due to the near field pressure dominates the overall mass of the BM, and thus significantly affects the micromechanical dynamics. This work not only quantifies the added mass of the OC due its own motion in the fluid, and shows that this is important, but also demonstrates that the coupling mass effect between the BM and OC significantly affects the dynamics of simple micromechanical models.

  11. Near field fluid coupling between internal motion of the organ of Corti and the basilar membrane

    NASA Astrophysics Data System (ADS)

    Elliott, Stephen J.; Ni, Guangjian

    2015-12-01

    The pressure distribution in each of the fluid chambers of the cochlea can be decomposed into a 1D, or plane wave, component and a near field component, which decays rapidly away from the excitation point. The transverse motion of the basilar membrane, BM, for example, generates both a 1D pressure field, which couples into the slow wave, and a local near field pressure, proportional to the BM acceleration, that generates an added mass on the BM due to the fluid motion. When the organ of Corti, OC, undergoes internal motion, due for example to outer hair cell activity, this motion will not itself generate any 1D pressure if the OC is incompressible and the BM is constrained not to move volumetrically, and so will not directly couple into the slow wave. This motion will, however, generate a near field pressure, proportional to the OC acceleration, which will act on the OC and thus increases its effective mass. The near field pressure due to this OC motion will also act on the BM, generating a force on the BM proportional to the acceleration of the OC, and thus create a "coupling mass" effect. By reciprocity, this coupling mass is the same as that acting on the OC due to the motion of the BM. This near field fluid coupling is initially observed in a finite element model of a slice of the cochlea. These simulations suggest a simple analytical formulation for the fluid coupling, using higher order beam modes across the width of the cochlear partition. It is well known that the added mass due to the near field pressure dominates the overall mass of the BM, and thus significantly affects the micromechanical dynamics. This work not only quantifies the added mass of the OC due its own motion in the fluid, and shows that this is important, but also demonstrates that the coupling mass effect between the BM and OC significantly affects the dynamics of simple micromechanical models.

  12. Near-field coupling model between PCB and grounded transmission line based on plane wave spectrum

    NASA Astrophysics Data System (ADS)

    Leseigneur, Christelle; Baudry, David; Ravelo, Blaise; Louis, Anne

    2013-10-01

    This article presents an explicit model of electromagnetic (EM) coupling between electronic circuits and metallic wire placed above the ground plane. The model is based on the interaction between the EM near-field (NF) that has been treated with plane wave spectrum (PWS) and the Taylor model. The routine process illustrating the methodology is addressed is this article. The practicability of the model developed was upheld with different analytical and real demonstrators. First, the NF coupling between a straight transmission line (TL) and 1 GHz Wilkinson power divider (PWD) designed and implemented in planar technology was provided. Subsequently, simulations with a powerful commercial tool and measurements from 0.2 GHz to 2 GHz revealed a good agreement between the coupling voltages from the proposed model. As a second proof of concept, a printed circuit board incorporating a 40 MHz RF oscillator was placed 5 mm above the grounded TL. Once again, coupling voltages matched measurements were observed with magnitude relative difference lower than 5 dB. The hereby model presents huge benefits not only in terms of flexibility in the design process but it can also be run with very less computation time compared to the existing standard simulators. The model can be potentially a good candidate for investigating complex systems EMC engineering.

  13. Resonance tuning due to Coulomb interaction in strong near-field coupled metamaterials

    SciTech Connect

    Roy Chowdhury, Dibakar; Xu, Ningning; Zhang, Weili; Singh, Ranjan

    2015-07-14

    Coulomb's law is one of the most fundamental laws of physics that describes the electrostatic interaction between two like or unlike point charges. Here, we experimentally observe a strong effect of Coulomb interaction in tightly coupled terahertz metamaterials where the split-ring resonator dimers in a unit cell are coupled through their near fields across the capacitive split gaps. Using a simple analytical model, we evaluated the Coulomb parameter that switched its sign from negative to positive values indicating the transition in the nature of Coulomb force from being repulsive to attractive depending upon the near field coupling between the split ring resonators. Apart from showing interesting effects in the strong coupling regime between meta-atoms, Coulomb interaction also allows an additional degree of freedom to achieve frequency tunable dynamic metamaterials.

  14. Resonance tuning due to Coulomb interaction in strong near-field coupled metamaterials

    NASA Astrophysics Data System (ADS)

    Roy Chowdhury, Dibakar; Xu, Ningning; Zhang, Weili; Singh, Ranjan

    2015-07-01

    Coulomb's law is one of the most fundamental laws of physics that describes the electrostatic interaction between two like or unlike point charges. Here, we experimentally observe a strong effect of Coulomb interaction in tightly coupled terahertz metamaterials where the split-ring resonator dimers in a unit cell are coupled through their near fields across the capacitive split gaps. Using a simple analytical model, we evaluated the Coulomb parameter that switched its sign from negative to positive values indicating the transition in the nature of Coulomb force from being repulsive to attractive depending upon the near field coupling between the split ring resonators. Apart from showing interesting effects in the strong coupling regime between meta-atoms, Coulomb interaction also allows an additional degree of freedom to achieve frequency tunable dynamic metamaterials.

  15. Accurate near-field calculation in the rigorous coupled-wave analysis method

    NASA Astrophysics Data System (ADS)

    Weismann, Martin; Gallagher, Dominic F. G.; Panoiu, Nicolae C.

    2015-12-01

    The rigorous coupled-wave analysis (RCWA) is one of the most successful and widely used methods for modeling periodic optical structures. It yields fast convergence of the electromagnetic far-field and has been adapted to model various optical devices and wave configurations. In this article, we investigate the accuracy with which the electromagnetic near-field can be calculated by using RCWA and explain the observed slow convergence and numerical artifacts from which it suffers, namely unphysical oscillations at material boundaries due to the Gibbs phenomenon. In order to alleviate these shortcomings, we also introduce a mathematical formulation for accurate near-field calculation in RCWA, for one- and two-dimensional straight and slanted diffraction gratings. This accurate near-field computational approach is tested and evaluated for several representative test-structures and configurations in order to illustrate the advantages provided by the proposed modified formulation of the RCWA.

  16. Fano profiles induced by near-field coupling in heterogeneous dimers of gold and silver nanoparticles.

    PubMed

    Bachelier, G; Russier-Antoine, I; Benichou, E; Jonin, C; Del Fatti, N; Vallée, F; Brevet, P-F

    2008-11-01

    The near-field coupling between a gold and a silver spherical nanoparticle is investigated theoretically. Fano profiles are observed in the absorption cross section of the gold nanoparticle due to the coupling between the spectrally localized surface plasmon resonance of the silver nanoparticle and the continuum of interband transitions of the gold one. The effect of dimer internal characteristics (particle sizes and distance), surrounding medium (through the refractive index), and external excitation (polarization and propagation directions) are addressed. In particular, it is shown that the near-field coupling can be tuned from the weak to the strong regime by rotating the polarization direction, and that the Fano profiles are sensitive to the shadowing effect even for small particle sizes. PMID:19113308

  17. Near-field coupling and resonant cavity modes in plasmonic nanorod metamaterials.

    PubMed

    Song, Haojie; Zhang, Junxi; Fei, Guangtao; Wang, Junfeng; Jiang, Kang; Wang, Pei; Lu, Yonghua; Iorsh, Ivan; Xu, Wei; Jia, Junhui; Zhang, Lide; Kivshar, Yuri S; Zhang, Lin

    2016-10-14

    Plasmonic resonant cavities are capable of confining light at the nanoscale, resulting in both enhanced local electromagnetic fields and lower mode volumes. However, conventional plasmonic resonant cavities possess large Ohmic losses at metal-dielectric interfaces. Plasmonic near-field coupling plays a key role in a design of photonic components based on the resonant cavities because of the possibility to reduce losses. Here, we study the plasmonic near-field coupling in the silver nanorod metamaterials treated as resonant nanostructured optical cavities. Reflectance measurements reveal the existence of multiple resonance modes of the nanorod metamaterials, which is consistent with our theoretical analysis. Furthermore, our numerical simulations show that the electric field at the longitudinal resonances forms standing waves in the nanocavities due to the near-field coupling between the adjacent nanorods, and a new hybrid mode emerges due to a coupling between nanorods and a gold-film substrate. We demonstrate that this coupling can be controlled by changing the gap between the silver nanorod array and gold substrate. PMID:27607837

  18. Near-Field Infrared Pump-Probe Imaging of Surface Phonon Coupling in Boron Nitride Nanotubes.

    PubMed

    Gilburd, Leonid; Xu, Xiaoji G; Bando, Yoshio; Golberg, Dmitri; Walker, Gilbert C

    2016-01-21

    Surface phonon modes are lattice vibrational modes of a solid surface. Two common surface modes, called longitudinal and transverse optical modes, exhibit lattice vibration along or perpendicular to the direction of the wave. We report a two-color, infrared pump-infrared probe technique based on scattering type near-field optical microscopy (s-SNOM) to spatially resolve coupling between surface phonon modes. Spatially varying couplings between the longitudinal optical and surface phonon polariton modes of boron nitride nanotubes are observed, and a simple model is proposed. PMID:26727539

  19. Temporal coupled-mode theory model for resonant near-field thermophotovoltaics

    SciTech Connect

    Karalis, Aristeidis; Joannopoulos, J. D.

    2015-10-05

    A temporal Coupled-Mode Theory model is developed to predict performance of resonant near-field ThermoPhotoVoltaic systems, which typically requires numerically intensive calculations. It is formulated for both orthogonal and non-orthogonal (coupled) modes and includes load-voltage dependencies and non-idealities, such as background absorption and radiation losses. Its good accuracy is confirmed by comparing with exact transfer-matrix calculations for two simple planar systems: a plasmonic emitter across a bulk semiconductor absorber and a metal-backed thin-film semiconductor emitter across an identical absorber.

  20. Light transport in dense composite media: role of near-field coupling

    NASA Astrophysics Data System (ADS)

    Rezvani Naraghi, Roxana; Sukhov, Sergey; Sáenz, Juan José; Dogariu, Aristide

    In scattering media, optical waves comprise both homogeneous and evanescent components. At very high concentrations of scatterers, particles are located in close proximity and interact through evanescent near fields. Thus, in this regime the energy is not only carried by propagating waves but it also evolves through evanescent coupling between individual scatterers. We have shown that in dense composite media additional transmission channels open because of these near-field interactions between close proximity scatters and, consequently, a new regime of transport emerges. This is clearly beyond simple descriptions of scatterers acting independently of their environment and framed in terms of far-field characteristics such as Mie cross-sections. We will show that, because in the dense media the energy can transfer through both diffusion and evanescent channels, the total transmittance is T =TCS +TNF = 1 1 L (lCS* +lNF*) L (lCS* +lNF*) . Correcting the total transmission in this manner is appealing because it is done in terms of physically meaningful and measurable quantities such a near-field (NF) scattering cross-section σNF.

  1. Collective properties and strong coupling in the near-field of a meta-surface

    NASA Astrophysics Data System (ADS)

    Felbacq, Didier

    2015-08-01

    Meta{surfaces or 2D metamaterials are generally seen as a device able to control the far-field behavior of light. Several studies have shown the possibility of controlling the polarization state, the directivity, the light-by-light manipulation or the generation of second harmonic signal. However, because of their resonant properties, meta{ surfaces also have interesting properties in the near-field. In the present work, a meta{surface made of a set of parallel line distributed dipoles was studied. The coupling of a quantum emitter with the photonic surface modes supported by the meta{surface is investigated.

  2. An ab-initio coupled mode theory for near field radiative thermal transfer.

    PubMed

    Chalabi, Hamidreza; Hasman, Erez; Brongersma, Mark L

    2014-12-01

    We investigate the thermal transfer between finite-thickness planar slabs which support surface phonon polariton modes (SPhPs). The thickness-dependent dispersion of SPhPs in such layered materials provides a unique opportunity to manipulate and enhance the near field thermal transfer. The key accomplishment of this paper is the development of an ab-initio coupled mode theory that accurately describes all of its thermal transfer properties. We illustrate how the coupled mode parameters can be obtained in a direct fashion from the dispersion relation of the relevant modes of the system. This is illustrated for the specific case of a semi-infinite SiC substrate placed in close proximity to a thin slab of SiC. This is a system that exhibits rich physics in terms of its thermal transfer properties, despite the seemingly simple geometry. This includes a universal scaling behavior of the thermal conductance with the slab thickness and spacing. The work highlights and further increases the value of coupled mode theories in rapidly calculating and intuitively understanding near-field transfer. PMID:25606933

  3. Hybrid modelling of near-field coupling onto grounded wire under ultra-short duration perturbation

    NASA Astrophysics Data System (ADS)

    Ravelo, B.; Liu, Y.

    2014-10-01

    A time-frequency (TF) hybrid model (HM) for investigating the interaction between EM near-field (NF) aggression and grounded wire is addressed. The HM is based on the combination of techniques for extracting the EM NF radiated by electronic structures and the calculation of electrical disturbances across the wire due to EM coupling. The computation method is fundamentally inspired from transmission line (TL) theory under EM illumination. The methodology including flow chart interpreting the routine algorithm based on the combination of frequency and time domain approaches is featured. An experimental result showing the EM coupling between patch antenna-wire from 1.5-3.5GHz reveals the efficiency of the HM in frequency domain. The relevance of this HM was illustrated with a structure comprised of 20cm aggressor and 5cm victim I-shaped wires placed above a planar ground plane. The aggressor was excited with 40ns duration perturbation signal. After Matlab implementation of the HM, the disturbance voltages across the extremity of the victim wire were extracted. This simple and fast HM is useful for the EMC engineering during the design and fabrication phases of electrical and electronic systems.

  4. From near-field to far-field coupling in the third dimension: retarded interaction of particle plasmons.

    PubMed

    Taubert, Richard; Ameling, Ralf; Weiss, Thomas; Christ, André; Giessen, Harald

    2011-10-12

    We study the transition from the near-field to the far-field coupling regime of particle plasmons in a three-dimensional geometry. In the far-field regime, retardation plays the dominant role and the plasmonic resonances are radiatively coupled. When the spatial arrangement of the oscillators is matched to their resonance wavelength, superradiant-like effects are observed. PMID:21879724

  5. Coupled near-field and far-field exposure assessment framework for chemicals in consumer products.

    PubMed

    Fantke, Peter; Ernstoff, Alexi S; Huang, Lei; Csiszar, Susan A; Jolliet, Olivier

    2016-09-01

    Humans can be exposed to chemicals in consumer products through product use and environmental emissions over the product life cycle. Exposure pathways are often complex, where chemicals can transfer directly from products to humans during use or exchange between various indoor and outdoor compartments until sub-fractions reach humans. To consistently evaluate exposure pathways along product life cycles, a flexible mass balance-based assessment framework is presented structuring multimedia chemical transfers in a matrix of direct inter-compartmental transfer fractions. By matrix inversion, we quantify cumulative multimedia transfer fractions and exposure pathway-specific product intake fractions defined as chemical mass taken in by humans per unit mass of chemical in a product. Combining product intake fractions with chemical mass in the product yields intake estimates for use in life cycle impact assessment and chemical alternatives assessment, or daily intake doses for use in risk-based assessment and high-throughput screening. Two illustrative examples of chemicals used in personal care products and flooring materials demonstrate how this matrix-based framework offers a consistent and efficient way to rapidly compare exposure pathways for adult and child users and for the general population. This framework constitutes a user-friendly approach to develop, compare and interpret multiple human exposure scenarios in a coupled system of near-field ('user' environment), far-field and human intake compartments, and helps understand the contribution of individual pathways to overall human exposure in various product application contexts to inform decisions in different science-policy fields for which exposure quantification is relevant. PMID:27318619

  6. Tunable Lattice Coupling of Multipole Plasmon Modes and Near-Field Enhancement in Closely Spaced Gold Nanorod Arrays

    PubMed Central

    Huang, Yu; Zhang, Xian; Ringe, Emilie; Hou, Mengjing; Ma, Lingwei; Zhang, Zhengjun

    2016-01-01

    Considering the nanogap and lattice effects, there is an attractive structure in plasmonics: closely spaced metallic nanoarrays. In this work, we demonstrate experimentally and theoretically the lattice coupling of multipole plasmon modes for closely spaced gold nanorod arrays, offering a new insight into the higher order cavity modes coupled with each other in the lattice. The resonances can be greatly tuned by changes in inter-rod gaps and nanorod heights while the influence of the nanorod diameter is relatively insignificant. Experimentally, pronounced suppressions of the reflectance are observed. Meanwhile, the near-field enhancement can be further enhanced, as demonstrated through surface enhanced Raman scattering (SERS). We then confirm the correlation between the near-field and far-field plasmonic responses, which is significantly important for maximizing the near-field enhancement at a specific excitation wavelength. This lattice coupling of multipole plasmon modes is of broad interest not only for SERS but also for other plasmonic applications, such as subwavelength imaging or metamaterials. PMID:26983501

  7. Tunable Lattice Coupling of Multipole Plasmon Modes and Near-Field Enhancement in Closely Spaced Gold Nanorod Arrays

    NASA Astrophysics Data System (ADS)

    Huang, Yu; Zhang, Xian; Ringe, Emilie; Hou, Mengjing; Ma, Lingwei; Zhang, Zhengjun

    2016-03-01

    Considering the nanogap and lattice effects, there is an attractive structure in plasmonics: closely spaced metallic nanoarrays. In this work, we demonstrate experimentally and theoretically the lattice coupling of multipole plasmon modes for closely spaced gold nanorod arrays, offering a new insight into the higher order cavity modes coupled with each other in the lattice. The resonances can be greatly tuned by changes in inter-rod gaps and nanorod heights while the influence of the nanorod diameter is relatively insignificant. Experimentally, pronounced suppressions of the reflectance are observed. Meanwhile, the near-field enhancement can be further enhanced, as demonstrated through surface enhanced Raman scattering (SERS). We then confirm the correlation between the near-field and far-field plasmonic responses, which is significantly important for maximizing the near-field enhancement at a specific excitation wavelength. This lattice coupling of multipole plasmon modes is of broad interest not only for SERS but also for other plasmonic applications, such as subwavelength imaging or metamaterials.

  8. Tunable Lattice Coupling of Multipole Plasmon Modes and Near-Field Enhancement in Closely Spaced Gold Nanorod Arrays.

    PubMed

    Huang, Yu; Zhang, Xian; Ringe, Emilie; Hou, Mengjing; Ma, Lingwei; Zhang, Zhengjun

    2016-01-01

    Considering the nanogap and lattice effects, there is an attractive structure in plasmonics: closely spaced metallic nanoarrays. In this work, we demonstrate experimentally and theoretically the lattice coupling of multipole plasmon modes for closely spaced gold nanorod arrays, offering a new insight into the higher order cavity modes coupled with each other in the lattice. The resonances can be greatly tuned by changes in inter-rod gaps and nanorod heights while the influence of the nanorod diameter is relatively insignificant. Experimentally, pronounced suppressions of the reflectance are observed. Meanwhile, the near-field enhancement can be further enhanced, as demonstrated through surface enhanced Raman scattering (SERS). We then confirm the correlation between the near-field and far-field plasmonic responses, which is significantly important for maximizing the near-field enhancement at a specific excitation wavelength. This lattice coupling of multipole plasmon modes is of broad interest not only for SERS but also for other plasmonic applications, such as subwavelength imaging or metamaterials. PMID:26983501

  9. Modeling of the Near Field Coupling Between an External Loop and an Implantable Spiral Chip Antennas in Biosensor Systems

    NASA Technical Reports Server (NTRS)

    Simons, Rainee N.; Miranda, Felix A.

    2006-01-01

    In this paper, the near field coupling between an external hand-held loop antenna and an implantable miniature (1x1 mm) printed square spiral chip antenna used in bio-MEMS sensors for contact-less powering and RF telemetry is investigated. The loop and the spiral are inductively coupled and effectively form a transformer. The numerical results include the quasi-stationary magnetic field pattern of the implanted antenna, near zone wave impedance as a function of the radial distance and the values of the lumped elements in the equivalent circuit model for the transformer.

  10. Enhanced near-field radiative heat transfer between a nanosphere and a hyperbolic metamaterial mediated by coupled surface phonon polaritons

    NASA Astrophysics Data System (ADS)

    Bai, Yang; Jiang, Yongyuan; Liu, Linhua

    2015-06-01

    We study the near-field radiative heat transfer between a silicon carbide (SiC) nanosphere and a SiC-SiO2 multi-layered hyperbolic metamaterial (HMM) by means of fluctuational electrodynamics. Results show that the absorbed mean power at the volume resonant frequency of the SiC nanosphere is one order of magnitude stronger than that of bulk SiC medium. This enhancement of near-field radiative heat transfer is mediated by the coupled surface phonon polaritons at the forbidden region of the Bloch mode. Moreover, the forbidden region of the Bloch mode is tuned by the geometry structure of the multi-layered HMM and overlapped with the volume resonant frequency of the SiC nanosphere, thus generating stronger absorption.

  11. Electromagnetically induced transparency with large delay-bandwidth product induced by magnetic resonance near field coupling to electric resonance

    SciTech Connect

    Li, Hai-ming; Liu, Shao-bin Liu, Si-yuan; Zhang, Hai-feng; Bian, Bo-rui; Kong, Xiang-kun; Wang, Shen-yun

    2015-03-16

    In this paper, we numerically and experimentally demonstrate electromagnetically induced transparency (EIT)-like spectral response with magnetic resonance near field coupling to electric resonance. Six split-ring resonators and a cut wire are chosen as the bright and dark resonator, respectively. An EIT-like transmission peak located between two dips can be observed with incident magnetic field excitation. A large delay bandwidth product (0.39) is obtained, which has potential application in quantum optics and communications. The experimental results are in good agreement with simulated results.

  12. Density controlled nanophotonic waveguide gratings for efficient on-chip out-coupling in the near field (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Vercruysse, Dries; Mukund, Vignesh; Jansen, Roelof; Stahl, Richard; Van Dorpe, Pol; Lagae, Liesbet; Rottenberg, Xavier

    2016-05-01

    Waveguide optics takes up a prominent role in the progressing miniaturization of optical devices. Chip integrated photonic waveguides especially allow for complex routing schemes of light across a chip. In/out-coupling diffraction gratings form an essential tool in waveguide systems, as they facilitate the interaction between the waveguide system and the near or far-field.[1,2] Ideally, these gratings would couple out all light in the waveguide into a beam with a predefined polarization and, phase and intensity profile. As such they should be able to produce any functional beam that is typically prepared by free space optics. Yet, in practice there is typically a design trade-off between beam quality and out-coupling efficiency.[2] Light in the waveguide has to travel laterally through the grating to be coupled out. The light therefore decays exponentially over the grating, causing much more light to be coupled out at the start of the grating than at the end. This asymmetry results in a warped out-coupling intensity that heavily influences the light beam's intensity profile. Especially when the grating is addressing points in the near field, as is the case for focusing waveguide grating couplers, this effect can be highly disruptive. In this work we present a grating constructed from a field of sub-wavelength scatterers, rather than full grating lines. By tuning the position and the density of the scatterers, the phase and the intensity of the out-coupled light can be set precisely over large grating areas. An iterative design algorithm is developed that carefully tunes the density so as to control the light intensity in the waveguide and the amount of out-coupled light. Using FDTD simulations we show that these gratings can efficiently couple out light into a nearly diffraction limited spot with an even angular intensity. We verify this experimentally by fabricating these gratings in the SiN/SiO2 system using e-beam lithography. In addition, we also show that

  13. Detection and processing of electromagnetic and near-field acoustic signals in elasmobranch fishes.

    PubMed Central

    Kalmijn, A D

    2000-01-01

    The acoustic near field of quietly moving underwater objects and the bio-electric field of aquatic animals exhibit great similarity, as both are predominantly governed by Laplace's equation. The acoustic and electrical sensory modalities thus may, in directing fishes to their prey, employ analogous processing algorithms, suggesting a common evolutionary design, founded on the salient physical features shared by the respective stimulus fields. Sharks and rays are capable of orientating to the earth's magnetic field and, hence, have a magnetic sense. The electromagnetic theory of orientation offers strong arguments for the animals using the electric fields induced by ocean currents and by their own motions in the earth's magnetic field. In the animal's frame of reference, in which the sense organs are at rest, the classical concept of motional electricity must be interpreted in relativistic terms. In the ampullae of Lorenzini, weak electric fields cause the ciliated apical receptor-cell membranes to produce graded, negative receptor currents opposite in direction to the fields applied. The observed currents form part of a positive-feedback mechanism, supporting the generation of receptor potentials much larger than the input signal. Acting across the basal cell membranes, the receptor potentials control the process of synaptic transmission. PMID:11079385

  14. Near-field examination of perovskite-based superlenses and superlens-enhanced probe-object coupling

    PubMed Central

    Kehr, S.C.; Liu, Y.M.; Martin, L.W.; Yu, P.; Gajek, M.; Yang, S.-Y.; Yang, C.-H.; Wenzel, M.T.; Jacob, R.; von Ribbeck, H.-G.; Helm, M.; Zhang, X.; Eng, L.M.; Ramesh, R.

    2011-01-01

    A planar slab of negative-index material works as a superlens with sub-diffraction-limited resolution, as propagating waves are focused and, moreover, evanescent waves are reconstructed in the image plane. Here we demonstrate a superlens for electric evanescent fields with low losses using perovskites in the mid-infrared regime. The combination of near-field microscopy with a tunable free-electron laser allows us to address precisely the polariton modes, which are critical for super-resolution imaging. We spectrally study the lateral and vertical distributions of evanescent waves around the image plane of such a lens, and achieve imaging resolution of λ/14 at the superlensing wavelength. Interestingly, at certain distances between the probe and sample surface, we observe a maximum of these evanescent fields. Comparisons with numerical simulations indicate that this maximum originates from an enhanced coupling between probe and object, which might be applicable for multifunctional circuits, infrared spectroscopy and thermal sensors. PMID:21427720

  15. Near-field examination of perovskite-based superlenses and superlens-enhanced probe-object coupling.

    PubMed

    Kehr, S C; Liu, Y M; Martin, L W; Yu, P; Gajek, M; Yang, S-Y; Yang, C-H; Wenzel, M T; Jacob, R; von Ribbeck, H-G; Helm, M; Zhang, X; Eng, L M; Ramesh, R

    2011-01-01

    A planar slab of negative-index material works as a superlens with sub-diffraction-limited resolution, as propagating waves are focused and, moreover, evanescent waves are reconstructed in the image plane. Here we demonstrate a superlens for electric evanescent fields with low losses using perovskites in the mid-infrared regime. The combination of near-field microscopy with a tunable free-electron laser allows us to address precisely the polariton modes, which are critical for super-resolution imaging. We spectrally study the lateral and vertical distributions of evanescent waves around the image plane of such a lens, and achieve imaging resolution of λ/14 at the superlensing wavelength. Interestingly, at certain distances between the probe and sample surface, we observe a maximum of these evanescent fields. Comparisons with numerical simulations indicate that this maximum originates from an enhanced coupling between probe and object, which might be applicable for multifunctional circuits, infrared spectroscopy and thermal sensors. PMID:21427720

  16. Note: Quasi-real-time analysis of dynamic near field scattering data using a graphics processing unit

    NASA Astrophysics Data System (ADS)

    Cerchiari, G.; Croccolo, F.; Cardinaux, F.; Scheffold, F.

    2012-10-01

    We present an implementation of the analysis of dynamic near field scattering (NFS) data using a graphics processing unit. We introduce an optimized data management scheme thereby limiting the number of operations required. Overall, we reduce the processing time from hours to minutes, for typical experimental conditions. Previously the limiting step in such experiments, the processing time is now comparable to the data acquisition time. Our approach is applicable to various dynamic NFS methods, including shadowgraph, Schlieren and differential dynamic microscopy.

  17. Optical security based on near-field processes at the nanoscale

    NASA Astrophysics Data System (ADS)

    Naruse, Makoto; Tate, Naoya; Ohtsu, Motoichi

    2012-09-01

    Optics has been playing crucial roles in security applications ranging from authentication and watermarks to anti-counterfeiting. However, since the fundamental physical principle involves optical far-fields, or propagating light, diffraction of light causes severe difficulties, for example in device scaling and system integration. Moreover, conventional security technologies in use today have been facing increasingly stringent demands to safeguard against threats such as counterfeiting of holograms, requiring innovative physical principles and technologies to overcome their limitations. Nanophotonics, which utilizes interactions between light and matter at the nanometer scale via optical near-field interactions, can break through the diffraction limit of conventional propagating light. Moreover, nanophotonics has some unique physical attributes, such as localized optical energy transfer and the hierarchical nature of optical near-field interactions, which pave the way for novel security functionalities. This paper reviews the physical principles and describes some experimental demonstrations of systems based on nanophotonics with respect to security applications such as tamper resistance against non-invasive and invasive attacks, hierarchical information retrieval, hierarchical holograms, authentication, and traceability.

  18. A coupled soil-fluid-structure simulation of the near-field earthquake effects on gravity type quay-walls

    NASA Astrophysics Data System (ADS)

    Zeinoddini, M.; Matin Nikoo, H.; Ahmadpour, F.

    2013-08-01

    This study focuses on non-linear seismic response of concrete gravity quay-wall structures subjected to near-fault ground motions, a subject which seems not to have received much attention in the literature. A two-dimensional coupled fluid-structure-soil finite element modelling is employed to obtain the quay-wall response. The seawater medium is represented by acoustic type, potential based fluid elements. The elasto-plastic behavior of the soil medium is idealized using Drucker-Prager yield criterion based on associated flow rule assumption. Four nodded plane strain elements are used to model the concrete wall, foundation, subsoil, backfill and seabed zones. Fluid Structure Interface (FSI) elements are considered between the seawater interfaces with the quay-wall and the seabed. Frictional contact elements are employed between the wall and soil interfaces. The numerical model is validated using field measurements available for permanent drifts in a quay-wall damaged during Kobe earthquake. Reasonable agreements are obtained between the model predictions and the field measurements. Non-linear seismic analyses of the selected quay-wall subjected to both near-fault and far-fault ground motions are performed. An incremental dynamic analysis approach (IDA) is used. In general, at least for models examined in the current study, the gravity quay-walls are found to be more vulnerable to near-field, in comparison with the corresponding far-field, earthquakes.

  19. Adaptive and robust statistical methods for processing near-field scanning microwave microscopy images.

    PubMed

    Coakley, K J; Imtiaz, A; Wallis, T M; Weber, J C; Berweger, S; Kabos, P

    2015-03-01

    Near-field scanning microwave microscopy offers great potential to facilitate characterization, development and modeling of materials. By acquiring microwave images at multiple frequencies and amplitudes (along with the other modalities) one can study material and device physics at different lateral and depth scales. Images are typically noisy and contaminated by artifacts that can vary from scan line to scan line and planar-like trends due to sample tilt errors. Here, we level images based on an estimate of a smooth 2-d trend determined with a robust implementation of a local regression method. In this robust approach, features and outliers which are not due to the trend are automatically downweighted. We denoise images with the Adaptive Weights Smoothing method. This method smooths out additive noise while preserving edge-like features in images. We demonstrate the feasibility of our methods on topography images and microwave |S11| images. For one challenging test case, we demonstrate that our method outperforms alternative methods from the scanning probe microscopy data analysis software package Gwyddion. Our methods should be useful for massive image data sets where manual selection of landmarks or image subsets by a user is impractical. PMID:25463325

  20. Direct-write PVDF nonwoven fiber fabric energy harvesters via the hollow cylindrical near-field electrospinning process

    NASA Astrophysics Data System (ADS)

    Liu, Z. H.; Pan, C. T.; Lin, L. W.; Huang, J. C.; Ou, Z. Y.

    2014-02-01

    One-dimensional piezoelectric nanomaterials have attracted great attention in recent years for their possible applications in mechanical energy scavenging devices. However, it is difficult to control the structural diameter, length, and density of these fibers fabricated by micro/nano-technologies. This work presents a hollow cylindrical near-field electrospinning (HCNFES) process to address production and performance issues encountered previously in either far-field electrospinning (FFES) or near-field electrospinning (NFES) processes. Oriented polyvinylidene fluoride (PVDF) fibers in the form of nonwoven fabric have been directly written on a glass tube for aligned piezoelectricity. Under a high in situ electrical poling field and strong mechanical stretching (the tangential speed on the glass tube collector is about 1989.3 mm s-1), the HCNFES process is able to uniformly deposit large arrays of PVDF fibers with good concentrations of piezoelectric β-phase. The nonwoven fiber fabric (NFF) is transferred onto a polyethylene terephthalate (PET) substrate and fixed at both ends using copper foil electrodes as a flexible textile-fiber-based PVDF energy harvester. Repeated stretching and releasing of PVDF NFF with a strain of 0.05% at 7 Hz produces a maximum peak voltage and current at 76 mV and 39 nA, respectively.

  1. Source processes of near-field deformation accompanying recent lava lake level decrease at Nyiragongo, DR. Congo

    NASA Astrophysics Data System (ADS)

    Geirsson, Halldor; Smets, Benoît; d'Oreye, Nicolas; Cayol, Valerie; Samsonov, Sergey; De Rauw, Dominique; Kervyn, Francois

    2016-04-01

    Nyiragongo volcano in the Democratic Republic of Congo, Central Africa, is one of the rare volcanoes that host a long-living lava lake. The evolution of this lava lake is very dynamic, with height changes spanning hundreds of meters over the past decades and including drastic height changes in relation to flank eruptions of the volcano in 1977 and 2002 (Smets et al., this meeting). Since September 30, 2011, the level of the lava lake has been progressively falling, reaching ~70 m below the lowest platform (termed "platform P3" hereafter) in July 2014. Platform P3 is constructed from successive overflows of the lava lake from 2002 to 2011, amounting to ~400 m thickness since the emptying of the lava lake following the 2002 flank eruption. Coinciding with the recent fall of the lava lake, differences of photogrammetry-derived DEM models, and InSAR time series, show a very near-field (out to ~200-300 m distance from the ~200 m-wide lava lake, i.e. on platform P3) deformation signal with up to meter-scale deformation near the crater. Ring-fractures have also formed in platform P3. Here we compare and contrast plausible models of processes contributing to this near-field deformation, including thermal contraction, elastic response, block rotation, structural weaknesses, and subsurface shape of the lava lake.

  2. Nano-material processing with laser radiation in the near field of a scanning probe tip

    NASA Astrophysics Data System (ADS)

    Jersch, J.; Demming, F.; Hildenhagen, J.; Dickmann, K.

    1998-04-01

    We report preliminary results of using a scanning probe microscope/laser combination to perform nanostructuring on insulator and metal surfaces in air. This technique enables processing of structures with a lateral resolution of approximately 10 nm. In this paper we present our last structuring results with both scanning tunnelling and scanning force microscopy. Some possible interaction mechanisms responsible for the structuring will be discussed.

  3. Departures from plane-wave-like coupling to a Maverick missile in the radiating near-field region of a horn antenna

    NASA Astrophysics Data System (ADS)

    Voss, D. E.; Koslover, R. A.; Cremer, C. D.; Silvestro, J.; Miner, L. M.

    1990-05-01

    The High Power Microwaves (HPM) susceptibility testing often requires irradiating test objects at the highest fluences possible. For aperture antennas, the highest fluences are generally found in the radiating near field region. For valid effects testing, the energy coupled to the object interior must accurately replicate that which would occur in a true weapon environment (plane wave illumination). Some believe that valid testing requires object placement at distances from the aperture exceeding 2 D squared/lambda (D=antenna effective diameter). Many also believe testing at farther away than 2 D squared/lambda guarantees plane wave-like coupling conditions. Neither view is correct. Testing in the reactive field region (less than lambda from the aperture) is generally invalid due to dominance of reactive coupling. For testing in the radiating near field, determination of validity is less trivial. An investigation was performed quantifying deviations from plane wave coupling. The measurements, using an instrumented Maverick missile in an anechoic chamber, and supported by theory, indicate conditions for which testing the Maverick missile accurately simulates plane wave coupling.

  4. Numerical study of the THM effects on the near-field safety of ahypothetical nuclear waste repository - BMT1 of the DECOVALEX IIIproject. Part 3: Effects of THM coupling in sparsely fracturedrocks

    SciTech Connect

    Rutqvist, J.; Chijimatsu, M.; Jing, L.; Millard, A.; Nguyen,T.S.; Rejeb, A.; Sugita, Y.; Tsang, C.F.

    2004-09-09

    BENCHPAR project, the impact of thermal-hydrological-mechanical (THM) couplings on the performance of a bentonite-back-filled nuclear waste repository in near-field crystalline rocks is evaluated in a Bench-Mark Test problem (BMT1) and the results are presented in a series of three companion papers in this issue. This is the third paper with focus on the effects of THM processes at a repository located in a sparsely fractured rock. Several independent coupled THM analyses presented in this paper show that THM couplings have the most significant impact on the mechanical stress evolution, which is important for repository design, construction and post-closure monitoring considerations. The results show that the stress evolution in the bentonite-back-filled excavations and the surrounding rock depends on the post-closure evolution of both fields of temperature and fluid pressure.It is further shown that the time required to full resaturation may play an important role for the mechanical integrity of the repository drifts.In this sense, the presence of hydraulically conducting fractures in the near-field rock might actually improve the mechanical performance of the repository. Hydraulically conducting fractures in the near-field rocks enhances the water supply to the buffers/back-fills, which promotes a more timely process of resaturation and development of swelling pressures in the back-fill, thus provides timely confining stress and support to the rock walls. In one particular case simulated in this study, it was shown that failure in the drift walls could be prevented if the compressive stresses in back-fill were fully developed within 50 years,which is when thermally induced rock strain begins to create high differential (failure-prone) stresses in the near-field rocks.

  5. Imaging cervical cytology with scanning near-field optical microscopy (SNOM) coupled with an IR-FEL

    PubMed Central

    Halliwell, Diane E.; Morais, Camilo L. M.; Lima, Kássio M. G.; Trevisan, Julio; Siggel-King, Michele R. F.; Craig, Tim; Ingham, James; Martin, David S.; Heys, Kelly A.; Kyrgiou, Maria; Mitra, Anita; Paraskevaidis, Evangelos; Theophilou, Georgios; Martin-Hirsch, Pierre L.; Cricenti, Antonio; Luce, Marco; Weightman, Peter; Martin, Francis L.

    2016-01-01

    Cervical cancer remains a major cause of morbidity and mortality among women, especially in the developing world. Increased synthesis of proteins, lipids and nucleic acids is a pre-condition for the rapid proliferation of cancer cells. We show that scanning near-field optical microscopy, in combination with an infrared free electron laser (SNOM-IR-FEL), is able to distinguish between normal and squamous low-grade and high-grade dyskaryosis, and between normal and mixed squamous/glandular pre-invasive and adenocarcinoma cervical lesions, at designated wavelengths associated with DNA, Amide I/II and lipids. These findings evidence the promise of the SNOM-IR-FEL technique in obtaining chemical information relevant to the detection of cervical cell abnormalities and cancer diagnosis at spatial resolutions below the diffraction limit (≥0.2 μm). We compare these results with analyses following attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy; although this latter approach has been demonstrated to detect underlying cervical atypia missed by conventional cytology, it is limited by a spatial resolution of ~3 μm to 30 μm due to the optical diffraction limit. PMID:27406404

  6. Imaging cervical cytology with scanning near-field optical microscopy (SNOM) coupled with an IR-FEL.

    PubMed

    Halliwell, Diane E; Morais, Camilo L M; Lima, Kássio M G; Trevisan, Julio; Siggel-King, Michele R F; Craig, Tim; Ingham, James; Martin, David S; Heys, Kelly A; Kyrgiou, Maria; Mitra, Anita; Paraskevaidis, Evangelos; Theophilou, Georgios; Martin-Hirsch, Pierre L; Cricenti, Antonio; Luce, Marco; Weightman, Peter; Martin, Francis L

    2016-01-01

    Cervical cancer remains a major cause of morbidity and mortality among women, especially in the developing world. Increased synthesis of proteins, lipids and nucleic acids is a pre-condition for the rapid proliferation of cancer cells. We show that scanning near-field optical microscopy, in combination with an infrared free electron laser (SNOM-IR-FEL), is able to distinguish between normal and squamous low-grade and high-grade dyskaryosis, and between normal and mixed squamous/glandular pre-invasive and adenocarcinoma cervical lesions, at designated wavelengths associated with DNA, Amide I/II and lipids. These findings evidence the promise of the SNOM-IR-FEL technique in obtaining chemical information relevant to the detection of cervical cell abnormalities and cancer diagnosis at spatial resolutions below the diffraction limit (≥0.2 μm). We compare these results with analyses following attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy; although this latter approach has been demonstrated to detect underlying cervical atypia missed by conventional cytology, it is limited by a spatial resolution of ~3 μm to 30 μm due to the optical diffraction limit. PMID:27406404

  7. Simulation of near-field and far-field optical properties of electromagnetically coupled multi-layered nanoparticles

    NASA Astrophysics Data System (ADS)

    Xu, Hongxing; Käll, Mikael

    2001-03-01

    Recent studies of nanoparticle-oligonucleotide conjugates^1 and “hot sites” in single-molecule surface-enhanced Raman scattering (SERS)^2 have highlighted the importance of clustering effects for the optical properties of metal nanoparticles. However, many applications in the life-sciences require coated nanoparticles, e.g. in order to induce biocompatibility or biorecognition. Such a coating will change the optical properties of the nanoparticle system. We here describe a calculational procedure that can be used to model the optical response of clusters composed of shelled spherical nanoparticles. Both far-field (e.g. extinction cross section) and near-field (e.g. SERS effect) optical properties can be evaluated. We will discuss how the wavelength dependent optical properties are influenced by core nanoparticle size and composition; surrounding medium; shell thickness and dielectric constant, and interparticle separation distance. ^1R. Elghanian et al., Science, 277, 1078 (1997); ^2H. Xu et al., Phys. Rev. Lett., 83, 4357 (1999) and Phys. Rev. E, 62, 4318 (2000)

  8. Simulations of near-field and far-field optical properties of electromagnetically coupled multi-layered nanoparticles

    NASA Astrophysics Data System (ADS)

    Xu, Hongxing

    2004-03-01

    Recent studies of nanoparticle-oligonucleotide conjugates[1] and "hot sites" in single-molecule surface-enhanced Raman scattering(SERS)[2] have highlighted the importance of clustering effects for the optical properties of metal nanoparticles. However, many applications in the life-sciences require coated nanoparticles, e.g. in order to induce biocompatibility or biorecognition. Such a coating will change the optical properties of nanoparticle system. We here describe a recursive method based on the extended Mie theory, which can be used to model the optical response clusters of shelled spherical nanoparticles. Both far-field (e.g. extinction cross section) and near-field (e.g. SERS effect) optical properties can be evaluated. We will discuss how the wavelength dependent optical properties are influenced by core nanoparticle size and composition; surrounding medium; shell thickness and dielectric constant, and interparticle separation distance. [1]R. Elghanian et al., Science, 277, 1078(1997); [2]H. Xu et al., Phys. Rev. Lett., 83, 4357(1999) and Phys. Rev. E, 62, 4318(2000)

  9. Some important mechanisms and processes in the near field of the Swedish repository for spent nuclear fuel

    SciTech Connect

    Neretnieks, I.

    1993-12-31

    In repositories for nuclear waste there are many processes that will be instrumental in damaging the canisters and releasing the nuclides. Based on experiences from studies of the performance of repositories and of an actual design, the major mechanisms influencing the integrity and performance of a repository are described and discussed. The paper addresses only conditions in crystalline rock repositories. The low water flow rate in fractures and channels plays a dominant role in limiting the interaction between water and waste. Molecular diffusion in the backfill and rock matrix, as well as in the mobile water, is an important transport process, but actually limits the exchange rate because diffusive transport is slow. Solubility limits of both waste matrix and of individual nuclides are also important. Complicating processes include alpha-radiolysis, which may change the water chemistry in the near-field. The sizes and locations of water flowpaths and damages in the canisters considerably influence the release rates. Uncertainties in data are large. Nevertheless the system is very robust in the sense that practically no reasonably conceivable assumptions or data will lead to large nuclide releases. Several natural analogues have been found to exhibit similarities with a waste repository and help to validate concepts and to increase our confidence that all major issues have been considered.

  10. A case study on the influence of THM coupling on the near field safety of a spent fuel repository in sparsely fractured granite

    SciTech Connect

    Nguyen, T.S.; Borgesson, L.; Chijimatsu, M.; Hernelind, J.; Jing, L.; Kobayashi, A.; Rutqvist, J.

    2009-03-01

    In order to demonstrate the feasibility of geological disposal of spent CANDU fuel in Canada, a safety assessment was performed for a hypothetical repository in the Canadian Shield. The assessment shows that such repository would meet international criteria for dose rate; however, uncertainties in the assumed evolution of the repository were identified. Such uncertainties could be resolved by the consideration of coupled Thermal-Hydro-Mechanical-Chemical (THMC) processes. In Task A of the DECOVALEX-THMC project, THM models were developed within the framework of the theory of poroelasticity. Such model development was performed in an iterative manner, using experimental data from laboratory and field tests. The models were used to perform near-field simulations of the evolution of the repository in order to address the above uncertainties. This paper presents the definition and rationale of task A and the results of the simulations. From a repository safety point of view, the simulations predict that the maximum temperature would be well below the design target of 100 C, however the load on the container can marginally exceed the design value of 15 MPa. However, the most important finding from the simulations is that a rock damage zone could form around the emplacement borehole. Such damage zone can extend a few metres from the walls of the emplacement holes, with permeability values that are orders of magnitude higher than the initial values. The damage zone has the potential to increase the radionuclide transport flux from the geosphere; the effect of such an increase should be taken into account in the safety assessment and mitigated if necessary by the provision of sealing systems.

  11. A case study on the influence of THM coupling on the near field safety of a spent fuel repository in sparsely fractured granite

    NASA Astrophysics Data System (ADS)

    Nguyen, Thanh Son; Börgesson, Lennart; Chijimatsu, Masakazu; Hernelind, Jan; Jing, Lanru; Kobayashi, Akira; Rutqvist, Jonny

    2009-05-01

    In order to demonstrate the feasibility of geological disposal of spent CANDU fuel in Canada, a safety assessment was performed for a hypothetical repository in the Canadian Shield. The assessment shows that the maximum long term radionuclide release from such repository would meet international criteria for dose rate; however, uncertainties in the assumed evolution of the repository were identified. Such uncertainties could be resolved by the consideration of coupled Thermal-Hydro-Mechanical-Chemical (THMC) processes. In Task A of the DECOVALEX-THMC project, THM models were developed within the framework of the theory of poroelasticity. Such model development was performed in an iterative manner, using experimental data from laboratory and field tests. The models were used to perform near-field simulations of the evolution of the repository in order to address the above-mentioned uncertainties. This paper presents the definition and rationale of task A and the results of the simulations. From a repository safety point of view, the simulations predict that the maximum temperature would be well below the design target of 100°C; however, the stress on the container can marginally exceed the design value of 15 MPa. However, the most important finding from the simulations is that a rock damage zone could form around the emplacement borehole. Such damage zone can extend a few metres from the walls of the emplacement holes, with permeability values that are orders of magnitude higher than the initial values. The damage zone has the potential to increase the radionuclide transport flux from the geosphere; the effect of such an increase should be taken into account in the safety assessment and mitigated if necessary by the provision of sealing systems.

  12. Joint inversion of teleseismic, geodetic, and near-field waveform datasets for rupture process of the 2015 Gorkha, Nepal, earthquake

    NASA Astrophysics Data System (ADS)

    Kobayashi, Hiroaki; Koketsu, Kazuki; Miyake, Hiroe; Takai, Nobuo; Shigefuji, Michiko; Bhattarai, Mukunda; Sapkota, Soma Nath

    2016-04-01

    The 2015 Gorkha earthquake and its aftershocks caused severe damage mostly in Nepal, while countries around the Himalayan region were warned for decades about large Himalayan earthquakes and the seismic vulnerability of these countries. However, the magnitude of the Gorkha earthquake was smaller than those of historical earthquakes in Nepal, and the most severe damage occurred in the north and northeast of Kathmandu. We explore reasons for these unexpected features by performing a joint source inversion of teleseismic, geodetic, and near-field waveform datasets to investigate the rupture process. Results indicate that the source fault was limited to the northern part of central Nepal and did not reach the Main Frontal Thrust. The zone of large slip was located in the north of Kathmandu, and the fault rupture propagated eastward with an almost constant velocity. Changes in the Coulomb failure function (ΔCFF) due to the Gorkha earthquake were computed, indicating that southern and western regions neighboring the source fault are potential source regions for future earthquakes related to the Gorkha earthquake. These two regions may correspond to the historical earthquakes of 1866 and 1344. Possible future earthquakes in the regions are predicted, and the warning for Himalayan seismic hazards remains high even after the Gorkha earthquake.

  13. Plasmon-induced transparency in metamaterials: Active near field coupling between bright superconducting and dark metallic mode resonators

    NASA Astrophysics Data System (ADS)

    Cao, Wei; Singh, Ranjan; Zhang, Caihong; Han, Jiaguang; Tonouchi, Masayoshi; Zhang, Weili

    2013-09-01

    Structured plasmonic metamaterial devices offer the design flexibility to be size scaled for operation across the electromagnetic spectrum and are extremely attractive for generating electromagnetically induced transparency and slow-light behaviors via coupling of bright and dark subwavelength resonators. Here, we experimentally demonstrate a thermally active superconductor-metal coupled resonator based hybrid terahertz metamaterial on a sapphire substrate that shows tunable transparency and slow light behavior as the metamaterial chip is cooled below the high-temperature superconducting phase transition temperature. This hybrid metamaterial opens up the avenues for designing micro-sized active circuitry with switching, modulation, and "slowing down terahertz light" capabilities.

  14. Bayesian exploration of coseismic seafloor deformation process during the 2011 Tohoku-Oki earthquake using near-field tsunami records

    NASA Astrophysics Data System (ADS)

    Jiang, J.; Simons, M.

    2014-12-01

    The diverse range of data for the 2011 Mw 9.0 Tohoku-oki earthquake are unprecedented. However, several models using joint data sets still disagree on the estimated slip distribution due to (1) choice of fault geometry and elastic structure; (2) choice of regularization scheme in optimization approaches; (3) lack or under-estimation of model prediction error due to imperfect forward modeling. Some important questions therefore remain unresolved, e.g., what is the profile of fault slip as one approaches the trench, and how much of the co-seismic signals is recorded in seafloor geodetic measurements. To obtain robust and detailed features of the co-seismic process, we present an approach to invert for the seafloor deformation field using only tsunami waveforms recorded by near-field stations, including GPS buoys, ocean bottom pressure gauges, cable pressure gauges and open ocean DART buoys. In addition to observational error, we incorporate model prediction error by considering the uncertainty in dispersion characteristics of tsunami propagation simulations. We adopt an analytical Bayesian approach to derive the posterior distributions for the coseismic seafloor deformation with minimal a priori assumptions. The analytical approach provides fast and robust characterization of coseismic seafloor deformation using the first arrivals of tsunami waveforms with potential for real-time applications. Our models show that large seafloor uplift is required at the trench, with maximum seafloor uplift occurring about 50 km from the trench. The actual fault slip depends on the assumed elastic structure and fault geometry; in the case of a homogeneous half-space and simplified fault geometry, slip decreases towards the trench. This method also provides direct comparisons with seafloor geodetic measurements and a quantitative estimation of the respective contributions from co- and post-seismic processes.

  15. The Role of Turbulence in Chemical and Dynamical Processes in the Near-Field Wake of Subsonic Aircraft

    NASA Technical Reports Server (NTRS)

    Lewellen, D. C.; Lewellen, W. Steve

    2002-01-01

    During this grant, covering the period from September 1998 to December 2001, we continued the investigation of the role of turbulent mixing in the wake of subsonic aircraft initiated in 1994 for NASA's Atmospheric Effects of Aviation Project. The goal of the research has been to provide sufficient understanding and quantitative analytical capability to assess the dynamical, chemical, and microphysical interactions in the near-field wake that have the greatest potential to influence the global atmospheric impact of the projected fleet of subsonic aircraft. Through large-eddy simulations we have shown that turbulence in the early wake dynamics can have a strong effect on both the ice microphysics of contrail evolution and on wake chemistry. The wake vortex dynamics are the primary determinant of the vertical extent of the contrail; this together with the local wind shear largely determines the horizontal extent. The fraction of the initial ice crystals surviving the wake vortex dynamics, their spatial distribution, and the ice mass distribution are all sensitive to the aircraft type, assumed initial ice crystal number, and ambient humidity and turbulence conditions. Our model indicates that there is a significant range of conditions for which a smaller aircraft such as a B737 produces as significant a persistent contrail as a larger aircraft such as a B747, even though the latter consumes almost five times as much fuel. Large-eddy simulations of the near wake of a B757 provided a fine-grained chemical-dynamical representation of simplified NOx - HOx chemistry in wakes of ages from a few seconds to several minutes. By sampling the simulated data in a manner similar to that of in situ aircraft measurements it was possible to provide a likely explanation for a puzzle uncovered in the 1996 SUCCESS flight measurements of OH and HO2 The results illustrate the importance of considering fluid dynamics effects in interpreting chemistry results when mixing rates and species

  16. Communication: dynamical embedding: correct quantum response from coupling TDDFT for a small cluster with classical near-field electrodynamics for an extended region.

    PubMed

    Gao, Yi; Neuhauser, Daniel

    2013-05-14

    We show how to obtain the correct electronic response of a large system by embedding; a small region is propagated by TDDFT (time-dependent density functional theory) simultaneously with a classical electrodynamics evolution using the Near-Field method over a larger external region. The propagations are coupled through a combined time-dependent density yielding a common Coulomb potential. We show that the embedding correctly describes the plasmonic response of a Mg(0001) slab and its influence on the dynamical charge transfer between an adsorbed H2O molecule and the substrate, giving the same spectral shape as full TDDFT (similar plasmon peak and molecular-dependent differential spectra) with much less computational effort. The results demonstrate that atomistic embedding electrodynamics is promising for nanoplasmonics and nanopolaritonics. PMID:23676021

  17. Communication: Dynamical embedding: Correct quantum response from coupling TDDFT for a small cluster with classical near-field electrodynamics for an extended region

    SciTech Connect

    Gao Yi; Neuhauser, Daniel

    2013-05-14

    We show how to obtain the correct electronic response of a large system by embedding; a small region is propagated by TDDFT (time-dependent density functional theory) simultaneously with a classical electrodynamics evolution using the Near-Field method over a larger external region. The propagations are coupled through a combined time-dependent density yielding a common Coulomb potential. We show that the embedding correctly describes the plasmonic response of a Mg(0001) slab and its influence on the dynamical charge transfer between an adsorbed H{sub 2}O molecule and the substrate, giving the same spectral shape as full TDDFT (similar plasmon peak and molecular-dependent differential spectra) with much less computational effort. The results demonstrate that atomistic embedding electrodynamics is promising for nanoplasmonics and nanopolaritonics.

  18. Coupling diffusion and high-pH precipitation/dissolution in the near field of a HLW repository in clay by means of reactive solute transport models

    NASA Astrophysics Data System (ADS)

    Samper, J.; Font, I.; Yang, C.; Montenegro, L.

    2004-12-01

    The reference concept for a HLW repository in clay in Spain includes a 75 cm thick bentonite buffer which surrounds canisters. A concrete sustainment 20 cm thick is foreseen between the bentonite buffer and the clay formation. The long term geochemical evolution of the near field is affected by a high-pH hyperalkaline plume induced by concrete. Numerical models of multicomponent reactive transport have been developped in order to quantify the evolution of the system over 1 Ma. Water flow is negligible once the bentonite buffer is saturated after about 20 years. Therefore, solute transport occurs mainly by diffusion. Models account for aqueous complexation, acid-base and redox reactions, cation exchange, and mineral dissolution precipitation in the bentonite, the concrete and the clay formation. Numerical results obtained witth CORE2D indicate that the high-pH plume causes significant changes in porewater chemistry both in the bentonite buffer and the clay formation. Porosity changes caused by mineral dissolution/precipitation are extremely important. Therefore, coupled modes of diffusion and reactive transport accounting for changes in porosity caused by mineral precipitation are required in order to obtain realistic predictions.

  19. Nanofabrication using near-field optical probes

    PubMed Central

    McLeod, Euan; Ozcan, Aydogan

    2012-01-01

    Nanofabrication using near-field optical probes is an established technique for rapid prototyping and automated maskless fabrication of nanostructured devices. In this review, we present the primary types of near-field probes and their physical processing mechanisms. Highlights of recent developments include improved resolution by optimizing the probe shape, incorporation of surface plasmonics in probe design, broader use in biological and magnetic storage applications, and increased throughput using probe arrays as well as high speed writing and patterning. PMID:22713756

  20. Land subsidence, structures and processes at the Dead Sea shoreline as revealed by a near-field photogrammetry survey at Ghor Haditha, Jordan

    NASA Astrophysics Data System (ADS)

    Al-Halbouni, Djamil; Holohan, Eoghan P.; Walter, Thomas; Alrshdan, Hussam; Sawarieh, Ali; Dahm, Torsten

    2015-04-01

    Rapid recession of the Dead Sea in the last few decades has led to an increasing rate of sinkhole formation around the lake shore. The development of these sinkholes and other land subsidence phenomena poses a major geological hazard to the local population, agriculture and industry. For a better understanding of the underlying physical processes and for determining current and future areas of sinkhole hazard, we conducted field investigations and a first low altitude ("near-field") aerial photogrammetric survey with a Helikite Balloon at Ghor Haditha, Jordan, in October 2014. From the near-field photogrammetry, we generated a high resolution Digital Elevation Model of the surveyed area. This enables a detailed quantification of sinkhole sizes and distribution as well of morphological parameters such as the sinkhole depth/diameter ratio (D). Values of the latter are generally greater in the mechanically stronger alluvial fan sediments (D = 3.0 - 0.4) than in the weaker muds of the former Dead Sea lakebed (D = 0.3 - 0.1). Importantly, the point of emanation of a very recent and sediment-laden stream at c. 10m below the former floor of the Dead Sea can be structurally and morphologically connected to the main sinkhole area. This provides evidence for channelised subterranean groundwater flows beneath this area. From our observations, two processes were identified as key factors for the development of large land subsidence structures and local sinkhole clusters: (1) Subrosion of weak material due to groundwater following preferred flow paths of ancient and current wadi riverbeds and (2) rapid dissolution of soluble material (salt) in this aragonite-rich mud. The heterogeneous geology and alternation of aquifers (alluvial fan sediments) and aquicludes (mud-flats) lead to the formation of complex subsurface flow channels that represent the secondary porosity of the internal structure of karst aquifers. As a consequence of these subterranean channels, local bending and

  1. DECOVALEX-THMC Task D: Long-Term Permeability/Porosity Changes inthe EDZ and Near Field due to THM and THC Processes in Volcanic andCrystaline-Bentonite Systems, Status Report October 2005

    SciTech Connect

    Birkholzer, J.; Rutqvist, J.; Sonnenthal, E.; Barr, D.

    2005-11-01

    The DECOVALEX project is an international cooperativeproject initiated by SKI, the Swedish Nuclear Power Inspectorate, withparticipation of about 10 international organizations. The name DECOVALEXstands for DEvelopment of COupled models and their VALidation againstExperiments. The general goal of this project is to encouragemultidisciplinary interactive and cooperative research on modelingcoupled processes in geologic formations in support of the performanceassessment for underground storage of radioactive waste. Three multi-yearproject stages of DECOVALEX have been completed in the past decade,mainly focusing on coupled thermal-hydrological-mechanicalprocesses.Currently, a fourth three-year project stage of DECOVALEX isunder way, referred to as DECOVALEX-THMC. THMC stands for Thermal,Hydrological, Mechanical, and Chemical processes. The new project stageaims at expanding the traditional geomechanical scope of the previousDECOVALEX project stages by incorporating geochemical processes importantfor repository performance. The U.S. Department of Energy (DOE) leadsTask D of the new DECOVALEX phase, entitled "Long-termPermeability/Porosity Changes in the EDZ and Near Field due to THC andTHM Processes for Volcanic and Crystalline-Bentonite Systems." In itsleadership role for Task D, DOE coordinates and sets the direction forthe cooperative research activities of the international research teamsengaged in Task D.

  2. Abstraction of Drift-Scale Coupled Processes

    SciTech Connect

    N.D. Francis; D. Sassani

    2000-03-31

    This Analysis/Model Report (AMR) describes an abstraction, for the performance assessment total system model, of the near-field host rock water chemistry and gas-phase composition. It also provides an abstracted process model analysis of potentially important differences in the thermal hydrologic (TH) variables used to describe the performance of a geologic repository obtained from models that include fully coupled reactive transport with thermal hydrology and those that include thermal hydrology alone. Specifically, the motivation of the process-level model comparison between fully coupled thermal-hydrologic-chemical (THC) and thermal-hydrologic-only (TH-only) is to provide the necessary justification as to why the in-drift thermodynamic environment and the near-field host rock percolation flux, the essential TH variables used to describe the performance of a geologic repository, can be obtained using a TH-only model and applied directly into a TSPA abstraction without recourse to a fully coupled reactive transport model. Abstraction as used in the context of this AMR refers to an extraction of essential data or information from the process-level model. The abstraction analysis reproduces and bounds the results of the underlying detailed process-level model. The primary purpose of this AMR is to abstract the results of the fully-coupled, THC model (CRWMS M&O 2000a) for effects on water and gas-phase composition adjacent to the drift wall (in the near-field host rock). It is assumed that drift wall fracture water and gas compositions may enter the emplacement drift before, during, and after the heating period. The heating period includes both the preclosure, in which the repository drifts are ventilated, and the postclosure periods, with backfill and drip shield emplacement at the time of repository closure. Although the preclosure period (50 years) is included in the process models, the postclosure performance assessment starts at the end of this initial period

  3. Novel concepts in near-field optics: from magnetic near-field to optical forces

    NASA Astrophysics Data System (ADS)

    Yang, Honghua

    near-field response of a linear rod antenna is studied with Babinet's principle. Babinet's principle connects the magnetic field of a structure to the electric field of its complement structure. Using combined far- and near-field spectroscopy, imaging, and theory, I identify magnetic dipole and higher order bright and dark magnetic resonances at mid-infrared frequencies. From resonant length scaling and spatial field distributions, I confirm that the theoretical requirement of Babinet's principle for a structure to be infinitely thin and perfectly conducting is still fulfilled to a good approximation in the mid-infrared. Thus Babinet's principle provides access to spatial and spectral magnetic field properties, leading to targeted design and control of magnetic optical antennas. Lastly, a novel form of nanoscale optical spectroscopy based on mechanical detection of optical gradient force is explored. It is to measure the optical gradient force between induced dipole moments of a sample and an atomic force microscope (AFM) tip. My study provides the theoretical basis in terms of spectral behavior, resonant enhancement, and distance dependence of the optical gradient force from numerical simulations for a coupled nanoparticle model geometry. I show that the optical gradient force is dispersive for local electronic and vibrational resonances, yet can be absorptive for collective polaronic excitations. This spectral behavior together with the distance dependence scaling provides the key characteristics for its measurement and distinction from competing processes such as thermal expansion. Furthermore, I provide a perspective for resonant enhancement and control of optical forces in general.

  4. Near-field optical microscopy nanoarray

    NASA Astrophysics Data System (ADS)

    Semin, David J.; Ambrose, W. Patrick; Goodwin, Peter M.; Wendt, Joel R.; Keller, Richard A.

    1997-04-01

    Multiplexing near-field scanning optical microscopy (NSOM) by the use of a nanoarray with parallel imaging is studied. The fabrication, characterization, and utilization of nanoarrays with approximately 100 nm diameter apertures spaced 500 nm center-to-center is presented. Extremely uniform nanoarrays with approximately 108 apertures were fabricated by electron beam lithography and reactive ion etching. The nanoarrays were characterized by atomic force microscopy and scanning electron microscopy. In this paper we utilize these nanoarrays in a laser-illuminated microscope with parallel detection on a charge-coupled device. Detection of B-phycoerythrin molecules using near- field illumination is presented. In principle, our system can be used to obtain high lateral resolution NSOM images over a wide-field of view (e.g. 50 - 100 micrometers ) within seconds.

  5. A near-field optical microscopy nanoarray

    SciTech Connect

    Semin, D.J.; Ambrose, W.P.; Goodwin, P.M.; Kwller, A.; Wendt, J.R.

    1996-12-31

    Multiplexing near-field scanning optical microscopy (NSOM) by the use of a nanoarray with parallel imaging is studied. The fabrication, characterization, and utilization of nanoarrays with {approximately} 100 nm diameter apertures spaced 500 nm center-to- center is presented. Extremely uniform nanoarrays with {approximately} 10{sup 8} apertures were fabricated by electron beam lithography and reactive ion etching. The nanoarrays were characterized by atomic force microscopy (AFM) and scanning electron microscopy (SEM). In this paper we utilize these nanoarrays in a laser-illuminated microscope with parallel detection on a charge- coupled device (CCD). Detection of B-phycoerythrin (B-PE) molecules using near-field illumination is presented. In principle, our system can be used to obtain high lateral resolution NSOM images over a wide-field of view (e.g. 50-100 {mu}m) within seconds.

  6. Antenna Near-Field Probe Station Scanner

    NASA Technical Reports Server (NTRS)

    Zaman, Afroz J. (Inventor); Lee, Richard Q. (Inventor); Darby, William G. (Inventor); Barr, Philip J. (Inventor); Lambert, Kevin M (Inventor); Miranda, Felix A. (Inventor)

    2011-01-01

    A miniaturized antenna system is characterized non-destructively through the use of a scanner that measures its near-field radiated power performance. When taking measurements, the scanner can be moved linearly along the x, y and z axis, as well as rotationally relative to the antenna. The data obtained from the characterization are processed to determine the far-field properties of the system and to optimize the system. Each antenna is excited using a probe station system while a scanning probe scans the space above the antenna to measure the near field signals. Upon completion of the scan, the near-field patterns are transformed into far-field patterns. Along with taking data, this system also allows for extensive graphing and analysis of both the near-field and far-field data. The details of the probe station as well as the procedures for setting up a test, conducting a test, and analyzing the resulting data are also described.

  7. Near-field/altered-zone models report

    SciTech Connect

    Hardin, E. L., LLNL

    1998-03-01

    lithophysal units. These units are made up of moderately to densely welded, devitrified, fractured tuff. The rock's chemical composition is comparable to that of typical granite, but has textural features and mineralogical characteristics of large-scale, silicic volcanism. Because the repository horizon will be approximately 300 m below the ground surface and 200 m above the water table, the repository will be partially saturated. The welded tuff matrix in the host units is highly impermeable, but water and gas flow readily through fractures. The degree of fracturing in these units is highly variable, and the hydrologic significance of fracturing is an important aspect of site investigation. This report describes the characterization and modeling of a region around the potential repository--the altered zone--a region in which the temperature will be increased significantly by waste-generated heat. Numerical simulation has shown that, depending on the boundary conditions, rock properties, and repository design features incorporated in the models, the altered zone (AZ) may extend from the water table to the ground surface. This report also describes models of the near field, the region comprising the repository emplacement drifts and the surrounding rock, which are critical to the performance of engineered components. Investigations of near-field and altered-zone (NF/AZ) processes support the design of underground repository facilities and engineered barriers and also provide constraint data for probabilistic calculations of waste-isolation performance (i.e., performance assessment). The approach to investigation, which is an iterative process involving hypothesis testing and experimentation, has relied on conceptualizing engineered barriers and on performance analysis. This report is a collection, emphasizing conceptual and numerical models, of the recent results contributed from studies of NF/AZ processes and of quantitative measures of NF/AZ performance. The selection and

  8. Radiation Entropy and Near-Field Thermophotovoltaics

    NASA Astrophysics Data System (ADS)

    Zhang, Zhuomin M.

    2008-08-01

    Radiation entropy was key to the original derivation of Planck's law of blackbody radiation, in 1900. This discovery opened the door to quantum mechanical theory and Planck was awarded the Nobel Prize in Physics in 1918. Thermal radiation plays an important role in incandescent lamps, solar energy utilization, temperature measurements, materials processing, remote sensing for astronomy and space exploration, combustion and furnace design, food processing, cryogenic engineering, as well as numerous agricultural, health, and military applications. While Planck's law has been fruitfully applied to a large number of engineering problems for over 100 years, questions have been raised about its limitation in micro/nano systems, especially at subwavelength distances or in the near field. When two objects are located closer than the characteristic wavelength, wave interference and photon tunneling occurs that can result in significant enhancement of the radiative transfer. Recent studies have shown that the near-field effects can realize emerging technologies, such as superlens, sub-wavelength light source, polariton-assisted nanolithography, thermophotovoltaic (TPV) systems, scanning tunneling thermal microscopy, etc. The concept of entropy has also been applied to explain laser cooling of solids as well as the second law efficiency of devices that utilize thermal radiation to produce electricity. However, little is known as regards the nature of entropy in near-field radiation. Some history and recent advances are reviewed in this presentation with a call for research of radiation entropy in the near field, due to the important applications in the optimization of thermophotovoltaic converters and in the design of practical systems that can harvest photon energies efficiently.

  9. Ionic contrast terahertz near field imaging

    NASA Astrophysics Data System (ADS)

    Gallot, Guilhem

    2013-09-01

    We demonstrated the direct and noninvasive imaging of functional neurons by Ionic Contrast Terahertz (ICT) near-field microscopy. This technique provides quantitative measurements of ionic concentrations in both the intracellular and extracellular compartments and opens the way to direct noninvasive imaging of neurons during electrical, toxin, or thermal stresses. Furthermore, neuronal activity results from both a precise control of transient variations in ionic conductance and a much less studied water exchange between the extracellular matrix and the intraaxonal compartment. The developed ICT technique associated with a full three-dimensional simulation of the axon-aperture near-field system allows a precise measurement of the axon geometry and therefore the direct visualization of neuron swelling induced by temperature change or neurotoxin poisoning. We also developed Terahertz Attenuated Total Reflection (ATR) devices perfectly suited for studying cell layers. Inserted in a terahertz time-domain system, and using a high resistivity low loss silicon prism to couple the terahertz wave into the sample, the detection scheme is based on the relative differential spectral phase of two orthogonal polarizations. Biological sample imaging as well as subwavelength (λ/16) longitudinal resolution are demonstrated.

  10. NASA-JSC antenna near-field measurement system

    NASA Technical Reports Server (NTRS)

    Cooke, W. P.; Friederich, P. G.; Jenkins, B. M.; Jameson, C. R.; Estrada, J. P.

    1988-01-01

    Work was completed on the near-field range control software. The capabilities of the data processing software were expanded with the addition of probe compensation. In addition, the user can process the measured data from the same computer terminal used for range control. The design of the laser metrology system was completed. It provides precise measruement of probe location during near-field measurements as well as position data for control of the translation beam and probe cart. A near-field range measurement system was designed, fabricated, and tested.

  11. Report of near field group

    SciTech Connect

    Palmer, R.B.; Baggett, N.; Claus, J.; Fernow, R.; Stumer, I.; Figueroa, H.; Kroll, N.; Funk, W.; Lee-Whiting, G.; Pickup, M.

    1985-04-01

    Substantial progress since the Los Alamos Workshop two years ago is reported. A radio-frequency model of a grating accelerator has been tested at Cornell, and extensive calculations compared with observations. Alternative structures consisting of either hemispherical bumps on a plane, or conducting spheres in space, have also been rf modeled. The use of liquid droplets to form such structures has been proposed and a conceptual design studied. Calculations and experiments have examined the effects of surface plasmas, and shown that in this case the reflectivity is low. However, calculations and observations suggest that gradients in excess of 1 GeV/meter should be obtainable without forming such plasma. An examination of wake fields shows that, with Landau damping, these are independent of wavelength. The use of near field structures to act as high gradient focusing elements has been studied and shows promise, independent of the acceleration mechanism. A proposal has been made to establish a facility that would enable ''proof of principle experiments'' to be performed on these and other laser driven accelerator mechanisms. 11 refs., 10 figs.

  12. Near field zones of quiet

    NASA Astrophysics Data System (ADS)

    Joseph, P.; Elliott, S. J.; Nelson, P. A.

    1994-05-01

    This paper examines the consequences of driving a single secondary loudspeaker to cancel the pressure due to some primary source at a point in its near field. This simple technique has been applied to the sound field in a highly reverberant room to produce zones of quiet in the vicinity of the loudspeaker, which have diameters that are typically equal to one-tenth of the acoustic wavelength, within which the sound pressure level is attenuated by at least 10 dB. The principal advantage gained with this strategy over other active techniques for controlling the sound field in rooms is that the sound pressure level well away from the control point is largely unaffected, an increase of only a small fraction of one dB being typical. Such a loudspeaker-microphone configuration could be located, for example, in the head rests of cars or aeroplanes, or indeed anywhere where the listener is seated for significant lengths of time and subjected to high ambient noise levels such that auditory comfort may be disturbed.

  13. Near-field thermodynamics and nanoscale energy harvesting

    NASA Astrophysics Data System (ADS)

    Latella, Ivan; Pérez-Madrid, Agustín; Lapas, Luciano C.; Rubi, J. Miguel

    2015-10-01

    We study the thermodynamics of near-field thermal radiation between two identical polar media at different temperatures. As an application, we consider an idealized energy harvesting process from sources at near room temperature at the nanoscale. We compute the maximum work flux that can be extracted from the radiation in the near-field regime and compare it with the corresponding maximum work flux in the blackbody regime. This work flux is considerably higher in the near-field regime. For materials that support surface phonon polaritons, explicit expressions for the work flux and an upper bound for the efficiency as functions of the surface wave frequency are obtained.

  14. Signal of microstrip scanning near-field optical microscope in far- and near-field zones.

    PubMed

    Morozov, Yevhenii M; Lapchuk, Anatoliy S

    2016-05-01

    An analytical model of interference between an electromagnetic field of fundamental quasi-TM(EH)00-mode and an electromagnetic field of background radiation at the apex of a near-field probe based on an optical plasmon microstrip line (microstrip probe) has been proposed. The condition of the occurrence of electromagnetic energy reverse flux at the apex of the microstrip probe was obtained. It has been shown that the nature of the interference depends on the length of the probe. Numerical simulation of the sample scanning process was conducted in illumination-reflection and illumination-collection modes. Results of numerical simulation have shown that interference affects the scanning signal in both modes. However, in illumination-collection mode (pure near-field mode), the signal shape and its polarity are practically insensible to probe length change; only signal amplitude (contrast) is slightly changed. However, changing the probe length strongly affects the signal amplitude and shape in the illumination-reflection mode (the signal formed in the far-field zone). Thus, we can conclude that even small background radiation can significantly influence the signal in the far-field zone and has practically no influence on a pure near-field signal. PMID:27140358

  15. Near Field Communication: Introduction and Implications

    ERIC Educational Resources Information Center

    McHugh, Sheli; Yarmey, Kristen

    2012-01-01

    Near field communication is an emerging technology that allows objects, such as mobile phones, computers, tags, or posters, to exchange information wirelessly across a small distance. Though primarily associated with mobile payment, near field communication has many different potential commercial applications, ranging from marketing to nutrition,…

  16. Source Rupture Process for the February 21, 2011, Mw6.1, New Zealand Earthquake and the Characteristics of Near-field Strong Ground Motion

    NASA Astrophysics Data System (ADS)

    Meng, L.; Shi, B.

    2011-12-01

    time duration to the observations, especially for the vertical component. Synthetics Fourier spectra are reasonably similar to the recordings. The simulated PGA values of vertical and S26W components are consistent with the recorded, and for the S64E component, the PGA derived from our simulation is smaller than that from observation. The resultant Fourier spectra both for the synthetic and observation is much similar with each other for three components of acceleration time histories, except for the vertical component, where the derived spectra from synthetic data is smaller than that resultant from observation when the frequency is above 10 Hz. Both theoretical study and numerical simulation indicate that, for the 2011 Mw 6.1, New Zealand Earthquake, the higher dynamic stress drop during the source rupture process could play an important role to the anomalous ground-motion amplification beside to the other site-related seismic effects. The composite source modeling based on the simple Brune's pulse model could approximately provide us a good insight into earthquake source related rupture processes for a moderate-sized earthquake.

  17. Attosecond nanoscale near-field sampling

    NASA Astrophysics Data System (ADS)

    Förg, B.; Schötz, J.; Süßmann, F.; Förster, M.; Krüger, M.; Ahn, B.; Okell, W. A.; Wintersperger, K.; Zherebtsov, S.; Guggenmos, A.; Pervak, V.; Kessel, A.; Trushin, S. A.; Azzeer, A. M.; Stockman, M. I.; Kim, D.; Krausz, F.; Hommelhoff, P.; Kling, M. F.

    2016-05-01

    The promise of ultrafast light-field-driven electronic nanocircuits has stimulated the development of the new research field of attosecond nanophysics. An essential prerequisite for advancing this new area is the ability to characterize optical near fields from light interaction with nanostructures, with sub-cycle resolution. Here we experimentally demonstrate attosecond near-field retrieval for a tapered gold nanowire. By comparison of the results to those obtained from noble gas experiments and trajectory simulations, the spectral response of the nanotaper near field arising from laser excitation can be extracted.

  18. Attosecond nanoscale near-field sampling.

    PubMed

    Förg, B; Schötz, J; Süßmann, F; Förster, M; Krüger, M; Ahn, B; Okell, W A; Wintersperger, K; Zherebtsov, S; Guggenmos, A; Pervak, V; Kessel, A; Trushin, S A; Azzeer, A M; Stockman, M I; Kim, D; Krausz, F; Hommelhoff, P; Kling, M F

    2016-01-01

    The promise of ultrafast light-field-driven electronic nanocircuits has stimulated the development of the new research field of attosecond nanophysics. An essential prerequisite for advancing this new area is the ability to characterize optical near fields from light interaction with nanostructures, with sub-cycle resolution. Here we experimentally demonstrate attosecond near-field retrieval for a tapered gold nanowire. By comparison of the results to those obtained from noble gas experiments and trajectory simulations, the spectral response of the nanotaper near field arising from laser excitation can be extracted. PMID:27241851

  19. Attosecond nanoscale near-field sampling

    PubMed Central

    Förg, B.; Schötz, J.; Süßmann, F.; Förster, M.; Krüger, M.; Ahn, B.; Okell, W. A.; Wintersperger, K.; Zherebtsov, S.; Guggenmos, A.; Pervak, V.; Kessel, A.; Trushin, S. A.; Azzeer, A. M.; Stockman, M. I.; Kim, D.; Krausz, F.; Hommelhoff, P.; Kling, M. F.

    2016-01-01

    The promise of ultrafast light-field-driven electronic nanocircuits has stimulated the development of the new research field of attosecond nanophysics. An essential prerequisite for advancing this new area is the ability to characterize optical near fields from light interaction with nanostructures, with sub-cycle resolution. Here we experimentally demonstrate attosecond near-field retrieval for a tapered gold nanowire. By comparison of the results to those obtained from noble gas experiments and trajectory simulations, the spectral response of the nanotaper near field arising from laser excitation can be extracted. PMID:27241851

  20. Attosecond nanoscale near-field sampling

    DOE PAGESBeta

    Forg, B.; Schotz, J.; SuBmann, F.; Forster, M.; Kruger, M.; Ahn, B.; Okell, W. A.; Wintersperger, K.; Zherebtsov, S.; Guggenmos, A.; et al

    2016-05-31

    The promise of ultrafast light-field-driven electronic nanocircuits has stimulated the development of the new research field of attosecond nanophysics. An essential prerequisite for advancing this new area is the ability to characterize optical near fields from light interaction with nanostructures, with sub-cycle resolution. Here we experimentally demonstrate attosecond near-field retrieval for a tapered gold nanowire. Furthermore, by comparison of the results to those obtained from noble gas experiments and trajectory simulations, the spectral response of the nanotaper near field arising from laser excitation can be extracted.

  1. Drift-Scale Coupled Processes (DST and THC Seepage) Models

    SciTech Connect

    E. Gonnenthal; N. Spyoher

    2001-02-05

    The purpose of this Analysis/Model Report (AMR) is to document the Near-Field Environment (NFE) and Unsaturated Zone (UZ) models used to evaluate the potential effects of coupled thermal-hydrologic-chemical (THC) processes on unsaturated zone flow and transport. This is in accordance with the ''Technical Work Plan (TWP) for Unsaturated Zone Flow and Transport Process Model Report'', Addendum D, Attachment D-4 (Civilian Radioactive Waste Management System (CRWMS) Management and Operating Contractor (M and O) 2000 [153447]) and ''Technical Work Plan for Nearfield Environment Thermal Analyses and Testing'' (CRWMS M and O 2000 [153309]). These models include the Drift Scale Test (DST) THC Model and several THC seepage models. These models provide the framework to evaluate THC coupled processes at the drift scale, predict flow and transport behavior for specified thermal loading conditions, and predict the chemistry of waters and gases entering potential waste-emplacement drifts. The intended use of this AMR is to provide input for the following: (1) Performance Assessment (PA); (2) Abstraction of Drift-Scale Coupled Processes AMR (ANL-NBS-HS-000029); (3) UZ Flow and Transport Process Model Report (PMR); and (4) Near-Field Environment (NFE) PMR. The work scope for this activity is presented in the TWPs cited above, and summarized as follows: continue development of the repository drift-scale THC seepage model used in support of the TSPA in-drift geochemical model; incorporate heterogeneous fracture property realizations; study sensitivity of results to changes in input data and mineral assemblage; validate the DST model by comparison with field data; perform simulations to predict mineral dissolution and precipitation and their effects on fracture properties and chemistry of water (but not flow rates) that may seep into drifts; submit modeling results to the TDMS and document the models. The model development, input data, sensitivity and validation studies described in

  2. Drift-Scale Coupled Processes (DST and THC Seepage) Models

    SciTech Connect

    E. Sonnenthale

    2001-04-16

    The purpose of this Analysis/Model Report (AMR) is to document the Near-Field Environment (NFE) and Unsaturated Zone (UZ) models used to evaluate the potential effects of coupled thermal-hydrologic-chemical (THC) processes on unsaturated zone flow and transport. This is in accordance with the ''Technical Work Plan (TWP) for Unsaturated Zone Flow and Transport Process Model Report'', Addendum D, Attachment D-4 (Civilian Radioactive Waste Management System (CRWMS) Management and Operating Contractor (M&O) 2000 [1534471]) and ''Technical Work Plan for Nearfield Environment Thermal Analyses and Testing'' (CRWMS M&O 2000 [153309]). These models include the Drift Scale Test (DST) THC Model and several THC seepage models. These models provide the framework to evaluate THC coupled processes at the drift scale, predict flow and transport behavior for specified thermal loading conditions, and predict the chemistry of waters and gases entering potential waste-emplacement drifts. The intended use of this AMR is to provide input for the following: Performance Assessment (PA); Near-Field Environment (NFE) PMR; Abstraction of Drift-Scale Coupled Processes AMR (ANL-NBS-HS-000029); and UZ Flow and Transport Process Model Report (PMR). The work scope for this activity is presented in the TWPs cited above, and summarized as follows: Continue development of the repository drift-scale THC seepage model used in support of the TSPA in-drift geochemical model; incorporate heterogeneous fracture property realizations; study sensitivity of results to changes in input data and mineral assemblage; validate the DST model by comparison with field data; perform simulations to predict mineral dissolution and precipitation and their effects on fracture properties and chemistry of water (but not flow rates) that may seep into drifts; submit modeling results to the TDMS and document the models. The model development, input data, sensitivity and validation studies described in this AMR are required

  3. Near field heat transfer in superlattices

    NASA Astrophysics Data System (ADS)

    Esquivel-Sirvent, Raul

    2015-03-01

    I present a theoretical calculation of the near field heat transfer between super lattices made of alternative layers of both metallic and semiconducting materials. The calculation of the near field transfer requires the knowledge of the reflectivities, that are obtained by calculating the surface impedance of the super lattice. Depending on the periodicity of the lattice and the dielectric function of the materials the near field heat transfer can be modulated or engineered. Additional control on the heat transfer is achieved by introducing defects in the superlattice. The results are extended to include photonic hypercrystals that effectively behave like a hyperbolic metamaterial even in the near field (1), where the tuning of the heat transfer is modified by Partial Support from DGAPA-UNAM project IN 111214.

  4. Millimeter wave near-field study

    NASA Technical Reports Server (NTRS)

    Kefauver, Neill

    1990-01-01

    The possibility is evaluated of current technology measuring large aperture millimeter wave antennas. Included are a mathematical modeling of system errors, experimental data supporting error model, predictions of system accuracy at millimeter wavelengths, advantage of near-field measurements, and a cost estimate for a facility upgrade. The use is emphasized of software compensation and other inexpensive alternatives to develop a near optimum solution to near-field measurement problems at millimeter wavelengths.

  5. Quantitative imaging of the optical near field.

    PubMed

    Kühler, Paul; García de Abajo, F Javier; Leiprecht, Philipp; Kolloch, Andreas; Solis, Javier; Leiderer, Paul; Siegel, Jan

    2012-09-24

    When exposing small particles on a substrate to a light plane wave, the scattered optical near field is spatially modulated and highly complex. We show, for the particular case of dielectric microspheres, that it is possible to image these optical near-field distributions in a quantitative way. By placing a single microsphere on a thin film of the photosensitive phase change material Ge(2)Sb(5)Te(5) and exposing it to a single short laser pulse, the spatial intensity modulation of the near field is imprinted into the film as a pattern of different material phases. The resulting patterns are investigated by using optical as well as high-resolution scanning electron microscopy. Quantitative information on the local optical near field at each location is obtained by calibrating the material response to pulsed laser irradiation. We discuss the influence of polarization and angle of incidence of the laser beam as well as particle size on the field distribution. The experimental results are in good quantitative agreement with a model based on a rigorous solution of Maxwell's equations. Our results have potential application to near-field optical lithography and experimental determination of near fields in complex nanostructures. PMID:23037356

  6. Thermal infrared near-field spectroscopy.

    PubMed

    Jones, Andrew C; Raschke, Markus B

    2012-03-14

    Despite the seminal contributions of Kirchhoff and Planck describing far-field thermal emission, fundamentally distinct spectral characteristics of the electromagnetic thermal near-field have been predicted. However, due to their evanescent nature their direct experimental characterization has remained elusive. Combining scattering scanning near-field optical microscopy with Fourier-transform spectroscopy using a heated atomic force microscope tip as both a local thermal source and scattering probe, we spectroscopically characterize the thermal near-field in the mid-infrared. We observe the spectrally distinct and orders of magnitude enhanced resonant spectral near-field energy density associated with vibrational, phonon, and phonon-polariton modes. We describe this behavior and the associated distinct on- and off-resonance nanoscale field localization with model calculations of the near-field electromagnetic local density of states. Our results provide a basis for intrinsic and extrinsic resonant manipulation of optical forces, control of nanoscale radiative heat transfer with optical antennas, and use of this new technique of thermal infrared near-field spectroscopy for broadband chemical nanospectroscopy. PMID:22280474

  7. Near-field thermodynamics: Useful work, efficiency, and energy harvesting

    SciTech Connect

    Latella, Ivan Pérez-Madrid, Agustín; Lapas, Luciano C.; Miguel Rubi, J.

    2014-03-28

    We show that the maximum work that can be obtained from the thermal radiation emitted between two planar sources in the near-field regime is much larger than that corresponding to the blackbody limit. This quantity, as well as an upper bound, for the efficiency of the process is computed from the formulation of thermodynamics in the near-field regime. The case when the difference of temperatures of the hot source and the environment is small, relevant for energy harvesting, is studied in detail. We also show that thermal radiation energy conversion can be more efficient in the near-field regime. These results open new possibilities for the design of energy converters that can be used to harvest energy from sources of moderate temperature at the nanoscale.

  8. Near-Field Photothermal Heating with a Plasmonic Nanofocusing Probe

    NASA Astrophysics Data System (ADS)

    Chen, Xiang; Dong, Biqing; Balogun, Oluwaseyi

    2016-03-01

    Noble metal nanostructures support plasmon resonances—collective oscillation of charge carriers at optical frequencies—and serve as effective tools to create bright light sources at the nanoscale. These sources are useful in broad application areas including, super-resolution imaging and spectroscopy, nanolithography, and near-field optomechanical transducers. The feasibility of these applications relies on efficient conversion of free-space propagating light to plasmons. Recently, we demonstrated a hybrid nanofocusing scheme for efficient coupling of light to plasmons at the apex of a scanning probe. In the approach, free-space light is coupled to propagating surface plasmon polaritons (SPPs) on the tapered shaft of the scanning probe. The SPPs propagate adiabatically towards the probe tip where they are coupled to localized plasmons (LSPs). The nanofocusing scheme was explored in a near-field scanning optical microscope for super-resolution imaging, near-field transduction of nanomechanical vibrations, and local detection of ultrasound. Owing to the strong concentration of light at the probe, significant heating of the tip and a sample positioned in the optical near-field is expected. This paper investigates the local heating produced by the plasmonic nanofocusing probe under steady-state conditions using the tip-enhanced Raman scattering approach. In addition, a finite element model is explored to study the coupling of free propagating light to LSPs, and to estimate the temperature rise expected in a halfspace heated by absorption of the LSPs. This study has implications for exploring the plasmonic nanofocusing probe in heat-assisted nanofabrication and fundamental studies of nanoscale heat transport in materials.

  9. Parallel scanning near-field photolithography: the snomipede.

    PubMed

    ul Haq, Ehtsham; Liu, Zhuming; Zhang, Yuan; Ahmad, Shahrul A Alang; Wong, Lu-Shin; Armes, Steven P; Hobbs, Jamie K; Leggett, Graham J; Micklefield, Jason; Roberts, Clive J; Weaver, John M R

    2010-11-10

    The “Millipede”, developed by Binnig and co-workers (Bining, G. K.; et al. IBM J. Res. Devel. 2000, 44, 323.), elegantly solves the problem of the serial nature of scanning probe lithography processes, by deploying massive parallelism. Here we fuse the “Millipede” concept with scanning near-field photolithography to yield a “Snomipede” that is capable of executing parallel chemical transformations at high resolution over macroscopic areas. Our prototype has sixteen probes that are separately controllable using a methodology that is, in principle, scalable to much larger arrays. Light beams generated by a spatial modulator or a zone plate array are coupled to arrays of cantilever probes with hollow, pyramidal tips. We demonstrate selective photodeprotection of nitrophenylpropyloxycarbonyl-protected aminosiloxane monolayers on silicon dioxide and subsequent growth of nanostructured polymer brushes by atom-transfer radical polymerization, and the fabrication of 70 nm structures in photoresist by a Snomipede probe array immersed under water. Such approaches offer a powerful means of integrating the top-down and bottom-up fabrication paradigms, facilitating the reactive processing of materials at nanometer resolution over macroscopic areas. PMID:20945880

  10. Active Extraction of Near-field Thermal Radiation

    NASA Astrophysics Data System (ADS)

    Ding, Ding; Kim, Taeyong; Minnich, Austin

    Radiative heat transport between materials supporting surface-phonon polaritons is greatly enhanced when the materials are placed at sub-wavelength separation as a result of the contribution of near-field surface modes. However, the enhancement is limited to small separations due to the evanescent decay of the surface waves. In this work, we propose and numerically demonstrate an active radiative cooling (ARC) scheme to extract these modes to the far-field. Our approach exploits the monochromatic nature of near-field thermal radiation to drive a transition in a laser gain medium, which, when coupled with external optical pumping, allows the resonant surface mode to be emitted into the far-field. We also provide further insights into our ARC scheme by applying the theoretical framework used for laser cooling of solids (LCS) to ARC. We show that LCS and ARC can be described with the same mathematical formalism by replacing the electron-phonon coupling parameter in LCS with the electron-photon coupling parameter in ARC. Using this framework, we examine the predictions of the formalism for LCS and ARC using realistic parameters and find that ARC can achieve higher efficiency and extracted power over a wide range of conditions. Our study demonstrates a new approach to manipulate near-field thermal radiation for thermal management.

  11. Controllable near-field intensity and spot size of hybrid terahertz metamaterial.

    PubMed

    Meng, Dejia; Hoque, M N F; Wang, Wei; Fan, Zhaoyang; Wang, Kejia; Lai, Jianjun; Chen, Changhong

    2015-04-15

    We report controllable near fields around split-ring resonator (SRR) gaps of an active terahertz metamaterial. As extension of parallel-plate capacitors, patterned VO2 is integrated into the metallic SRRs to manipulate the near-field intensity and hot spot size through its metal-insulator transition. This design enhances the device reliability by preventing VO2 dielectric breakdown at a strongly enhanced near field. The near-field intensity and spot size are tunable in broad ranges, and the device is demonstrated to be capable of compensating resonant frequency drift arisen from different interactions due to near-field coupling. It provides an effective method to actively manipulate the light-matter interaction through the strongly enhanced and tunable near fields. PMID:25872063

  12. Volumetric Near-Field Microwave Plasma Generation

    NASA Technical Reports Server (NTRS)

    Exton, R. J.; Balla, R. Jeffrey; Herring, G. C.; Popovic, S.; Vuskovic, L.

    2003-01-01

    A periodic series of microwave-induced plasmoids is generated using the outgoing wave from a microwave horn and the reflected wave from a nearby on-axis concave reflector. The plasmoids are spaced at half-wavelength separations according to a standing-wave pattern. The plasmoids are enhanced by an effective focusing in the near field of the horn (Fresnel region) as a result of a diffractive narrowing. Optical imaging, electron density, and rotational temperature measurements characterize the near field plasma region. Volumetric microwave discharges may have application to combustion ignition in scramjet engines.

  13. Near-field scanning study for radio frequency interference estimation

    NASA Astrophysics Data System (ADS)

    Pan, Jingnan

    This dissertation discusses the novel techniques using near-fields scanning to do radio frequency interference (RFI) estimation. As the electronic products are becoming more and more complicated, the radio frequency (RF) receiver in the system is very likely interfered by multiple noise sources simultaneously. A method is proposed to identify the interference from different noise sources separately, even when they are radiating at the same time. This method is very helpful for engineers to identify the contribution of the coupling from different sources and further solve the electromagnetic interference issues efficiently. On the other hand, the equivalent dipole-moment models and a decomposition method based on reciprocity theory can also be used together to estimate the coupling from the noise source to the victim antennas. This proposed method provides convenience to estimate RFI issues in the early design stage and saves the time of RFI simulation and measurements. The finite element method and image theory can also predict the far fields of the radiation source, locating above a ground plane. This method applies the finite element method (FEM) to get the equivalent current sources from the tangential magnetic near fields. With the equivalent current sources, the far-field radiation can be calculated based on Huygens's Principle and image theory. By using only the magnetic near fields on the simplified Huygens's surface, the proposed method significantly saves measurement time and cost while also retaining good far-field prediction.

  14. Near-field compact dielectric optics

    NASA Astrophysics Data System (ADS)

    Feuermann, Daniel; Gordon, Jeffrey M.; Ng, Tuck Wah

    2006-08-01

    Aplanatic optics crafted from transparent dielectrics can approach the etendue limit for radiative transfer in pragmatic near-field systems. Illustrations are presented for the more demanding realm of high numerical aperture (NA) at the source and/or target. These light couplers can alleviate difficulties in aligning system components, and can achieve the fundamental compactness limit for optical devices that satisfy Fermat's principle.

  15. Active thermal extraction of near-field thermal radiation

    NASA Astrophysics Data System (ADS)

    Ding, D.; Kim, T.; Minnich, A. J.

    2016-02-01

    Radiative heat transport between materials supporting surface-phonon polaritons is greatly enhanced when the materials are placed at subwavelength separation as a result of the contribution of near-field surface modes. However, the enhancement is limited to small separations due to the evanescent decay of the surface waves. In this work, we propose and numerically demonstrate an active scheme to extract these modes to the far field. Our approach exploits the monochromatic nature of near-field thermal radiation to drive a transition in a laser gain medium, which, when coupled with external optical pumping, allows the resonant surface mode to be emitted into the far field. Our study demonstrates an approach to manipulate thermal radiation that could find applications in thermal management.

  16. Near-field NanoThermoMechanical memory

    SciTech Connect

    Elzouka, Mahmoud; Ndao, Sidy

    2014-12-15

    In this letter, we introduce the concept of NanoThermoMechanical Memory. Unlike electronic memory, a NanoThermoMechanical memory device uses heat instead of electricity to record, store, and recover data. Memory function is achieved through the coupling of near-field thermal radiation and thermal expansion resulting in negative differential thermal resistance and thermal latching. Here, we demonstrate theoretically via numerical modeling the concept of near-field thermal radiation enabled negative differential thermal resistance that achieves bistable states. Design and implementation of a practical silicon based NanoThermoMechanical memory device are proposed along with a study of its dynamic response under write/read cycles. With more than 50% of the world's energy losses being in the form of heat along with the ever increasing need to develop computer technologies which can operate in harsh environments (e.g., very high temperatures), NanoThermoMechanical memory and logic devices may hold the answer.

  17. Near-field heat transfer between gold nanoparticle arrays

    SciTech Connect

    Phan, Anh D.; Phan, The-Long; Woods, Lilia M.

    2013-12-07

    The radiative heat transfer between gold nanoparticle layers is presented using the coupled dipole method. Gold nanoparticles are modelled as effective electric and magnetic dipoles interacting via electromagnetic fluctuations. The effect of higher-order multipoles is implemented in the expression of electric polarizability to calculate the interactions at short distances. Our findings show that the near-field radiation reduces as the radius of the nanoparticles is increased. Also, the magnetic dipole contribution to the heat exchange becomes more important for larger particles. When one layer is displayed in parallel with respect to the other layer, the near-field heat transfer exhibits oscillatory-like features due to the influence of the individual nanostructures. Further details about the effect of the nanoparticles size are also discussed.

  18. Coping Processes of Couples Experiencing Infertility

    ERIC Educational Resources Information Center

    Peterson, Brennan D.; Newton, Christopher R.; Rosen, Karen H.; Schulman, Robert S.

    2006-01-01

    This study explored the coping processes of couples experiencing infertility. Participants included 420 couples referred for advanced reproductive treatments. Couples were divided into groups based on the frequency of their use of eight coping strategies. Findings suggest that coping processes, which are beneficial to individuals, may be…

  19. Noise analysis for near-field 3D FM-CW radar imaging systems

    NASA Astrophysics Data System (ADS)

    Sheen, David M.

    2015-05-01

    Near field radar imaging systems are used for demanding security applications including concealed weapon detection in airports and other high-security venues. Despite the near-field operation, phase noise and thermal noise can limit performance in several ways. Practical imaging systems can employ arrays with low gain antennas and relatively large signal distribution networks that have substantial losses which limit transmit power and increase the effective noise figure of the receiver chain, resulting in substantial thermal noise. Phase noise can also limit system performance. The signal coupled from transmitter to receiver is much larger than expected target signals. Phase noise from this coupled signal can set the system noise floor if the oscillator is too noisy. Frequency modulated continuous wave (FM-CW) radar transceivers used in short range systems are relatively immune to the effects of the coupled phase noise due to range correlation effects. This effect can reduce the phase-noise floor such that it is below the thermal noise floor for moderate performance oscillators. Phase noise is also manifested in the range response around bright targets, and can cause smaller targets to be obscured. Noise in synthetic aperture imaging systems is mitigated by the processing gain of the system. In this paper, the effects of thermal noise, phase noise, and processing gain are analyzed in the context of a near field 3-D FM-CW imaging radar as might be used for concealed weapon detection. In addition to traditional frequency domain analysis, a time-domain simulation is employed to graphically demonstrate the effect of these noise sources on a fast-chirping FM-CW system.

  20. From classical to modern near-field optics and the future

    NASA Astrophysics Data System (ADS)

    Ohtsu, Motoichi

    2014-11-01

    This paper reviews the framework of classical near-field optics and recent progress in modern near-field optics. Some applications are also reviewed, including novel optical functional devices, nano-fabrication technologies, energy conversion technologies, and information processing systems. Novel theoretical models based on mathematical science are also presented, as well as an outlook for the future, hinting at the possibilities of near-field optics.

  1. Evaluation of near-field earthquake effects

    SciTech Connect

    Shrivastava, H.P.

    1994-11-01

    Structures and equipment, which are qualified for the design basis earthquake (DBE) and have anchorage designed for the DBE loading, do not require an evaluation of the near-field earthquake (NFE) effects. However, safety class 1 acceleration sensitive equipment such as electrical relays must be evaluated for both NFE and DBE since they are known to malfunction when excited by high frequency seismic motions.

  2. Bicollimated near-field Gregorian reflector antenna

    NASA Astrophysics Data System (ADS)

    Rao, J. B. L.

    1983-02-01

    A bicollimated near-field Gregorian reflector is structurally similar to a classical confocal parabolic reflector, but its surfaces are shaped to have better scan capability. A geometrical optics procedure is used in designing the reflector surfaces. A three dimensional ray tracing procedure is used in analyzing the aperture phase errors as the beam is scanned to different angles. The results show that the bicollimated configuration has about 45% greater angular scanning range than the corresponding confocal parabolic dual-reflector system.

  3. Hill Ciphers over Near-Fields

    ERIC Educational Resources Information Center

    Farag, Mark

    2007-01-01

    Hill ciphers are linear codes that use as input a "plaintext" vector [p-right arrow above] of size n, which is encrypted with an invertible n x n matrix E to produce a "ciphertext" vector [c-right arrow above] = E [middle dot] [p-right arrow above]. Informally, a near-field is a triple [left angle bracket]N; +, *[right angle bracket] that…

  4. Near-field radiofrequency electromagnetic exposure assessment.

    PubMed

    Rubtsova, Nina; Perov, Sergey; Belaya, Olga; Kuster, Niels; Balzano, Quirino

    2015-09-01

    Personal wireless telecommunication devices, such as radiofrequency (RF) electromagnetic field (EMF) sources operated in vicinity of human body, have possible adverse health effects. Therefore, the correct EMF assessment is necessary in their near field. According to international near-field measurement criteria, the specific absorption rate (SAR) is used for absorbed energy distribution assessment in tissue simulating liquid phantoms. The aim of this investigation is to validate the relationship between the H-field of incident EMF and absorbed energy in phantoms. Three typical wireless telecommunication system frequencies are considered (900, 1800 and 2450 MHz). The EMF source at each frequency is an appropriate half-wave dipole antenna and the absorbing medium is a flat phantom filled with the suitable tissue simulating liquid. Two methods for SAR estimation have been used: standard procedure based on E-field measured in tissue simulating medium and a proposed evaluation by measuring the incident H-field. Compared SAR estimations were performed for various distances between sources and phantom. Also, these research data were compared with simulation results, obtained by using finite-difference time-domain method. The acquired data help to determine the source near-field space characterized by the smallest deviation between SAR estimation methods. So, this region near the RF source is suitable for correct RF energy absorption assessment using the magnetic component of the RF fields. PMID:26444190

  5. Ideal near-field thermophotovoltaic cells

    NASA Astrophysics Data System (ADS)

    Molesky, Sean; Jacob, Zubin

    2015-05-01

    We ask the question, what are the ideal characteristics of a near-field thermophotovoltaic cell? Our search leads us to a reformulation of near-field radiative heat transfer in terms of the joint density of electronic states of the emitter-absorber pair in the thermophotovoltaic system. This form reveals that semiconducting materials with narrowband absorption spectra are critical to the energy-conversion efficiency. This essential feature is unavailable in conventional bulk semiconductor cells but can be obtained using low-dimensional materials. Our results show that the presence of matched van Hove singularities resulting from quantum confinement in the emitter and absorber of a thermophotovoltaic cell boosts both the magnitude and spectral selectivity of radiative heat transfer, dramatically improving energy-conversion efficiency. We provide a model near-field thermophotovoltaic system design making use of this idea by employing the van Hove singularities present in carbon nanotubes. Shockley-Queisser analysis shows that the predicted heat transfer characteristics of this model device are fundamentally better than existing thermophotovoltaic designs. Our work paves the way for the use of quantum dots, quantum wells, two-dimensional semiconductors, semiconductor nanowires, and carbon nanotubes as future materials for thermophotovoltaic cells.

  6. Near-field millimeter - wave imaging of nonmetallic materials

    SciTech Connect

    Gopalsami, N.; Bakhtiari, S.; Raptis, A.C.

    1996-12-31

    A near-field millimeter-wave (mm-wave) imaging system has been designed and built in the 94-GHz range for on-line inspection of nonmetallic (dielectric) materials. The imaging system consists of a transceiver block coupled to an antenna that scans the material to be imaged; a reflector plate is placed behind the material. A quadrature IF mixer in the transceiver block enables measurement of in-phase and quadrature-phase components of reflected signals with respect to the transmitted signal. All transceiver components, with the exception of the Gunn-diode oscillator and antenna, were fabricated in uniform blocks and integrated and packaged into a compact unit (12.7 x 10.2 x 2.5 cm). The objective of this work is to test the applicability of a near-field compact mm-wave sensor for on-line inspection of sheetlike materials such as paper, fabrics, and plastics. This paper presents initial near-field mm-wave images of paper and fabric samples containing known artifacts.

  7. Tip-enhanced near-field optical microscopy

    PubMed Central

    Mauser, Nina; Hartschuh, Achim

    2013-01-01

    Tip-enhanced near-field optical microscopy (TENOM) is a scanning probe technique capable of providing a broad range of spectroscopic information on single objects and structured surfaces at nanometer spatial resolution and with highest detection sensitivity. In this review, we first illustrate the physical principle of TENOM that utilizes the antenna function of a sharp probe to efficiently couple light to excitations on nanometer length scales. We then discuss the antenna-induced enhancement of different optical sample responses including Raman scattering, fluorescence, generation of photocurrent and electroluminescence. Different experimental realizations are presented and several recent examples that demonstrate the capabilities of the technique are reviewed. PMID:24100541

  8. Evaluation of near field rock treatment during constructions (LADSfeature #22)

    SciTech Connect

    Sonnenthal, Eric; Spycher, Nicolas

    1998-11-24

    The purpose of this report is to evaluate the effect of near-field rock treatment by injection of reactive material (calcite) above the drift for the purpose of decreasing postclosure drift seepage. The method used for the calculation was a coupled reaction-transport numerical model for gas-water-rock interaction. This includes the mass conservation of heat, liquid and gas for thermohydrological calculations, of aqueous and gaseous species for advective and diffusive transport, and the kinetics of mineral-water reactions.

  9. Near-field Interferometric Imaging of Lightning

    NASA Astrophysics Data System (ADS)

    Stock, M.; Wu, T.; Akiyama, Y.; Kawasaki, Z.; Ushio, T.

    2015-12-01

    In the past, lightning interferometric mapping systems assumed that a source is very far from the measurement location. The assumption greatly simplifies the mathematics needed to locate the source, but the resulting source positions are limited to two spatial dimensions (azimuth and elevation). For short baseline systems, this assumption is very good because the source is almost always much farther away than the diameter of the array, making three-dimensional location all but impossible. By removing the far-field assumption, if the array is large enough it is possible to locate the source in three spatial dimensions using purely interferometric techniques. The purely interferometric method is quite different from the more typical time-of-arrival method. Instead of measuring arrival times or time differences of the radiation arriving at each station, a volume is imaged over a some integration period and then searched for a source. It is not necessary to know that a source exists in the integration period for the interferometric imaging technique to produce a well defined solution. Interferometric imaging can locate sources buried in noise, can locate both continuous and impulsive emission, and is capable of locating multiple simultaneously radiating sources. If the waveforms are corrected for propagation delay to the search volume, the integration period can be made arbitrarily small (limited only by the frequencies being observed), allowing the progression of lightning to be examined in detail. Near-field interferometry works equally well on a wide range of different signal types, from the LF to VHF bands in radio, or even on acoustic emissions from lightning. Near-field imaging can be used to correct the angular locations of short baseline systems when a source is very close to the array, or to produce full three-dimensional maps of lightning with long baseline arrays. Presented here are preliminary results of applying near-field interferometric imaging to the

  10. Scanning tip microwave near field microscope

    DOEpatents

    Xiang, X.D.; Schultz, P.G.; Wei, T.

    1998-10-13

    A microwave near field microscope has a novel microwave probe structure wherein the probing field of evanescent radiation is emitted from a sharpened metal tip instead of an aperture or gap. This sharpened tip, which is electrically and mechanically connected to a central electrode, extends through and beyond an aperture in an end wall of a microwave resonating device such as a microwave cavity resonator or a microwave stripline resonator. Since the field intensity at the tip increases as the tip sharpens, the total energy which is radiated from the tip and absorbed by the sample increases as the tip sharpens. The result is improved spatial resolution without sacrificing sensitivity. 17 figs.

  11. Scanning tip microwave near field microscope

    DOEpatents

    Xiang, Xiao-Dong; Schultz, Peter G.; Wei, Tao

    1998-01-01

    A microwave near field microscope has a novel microwave probe structure wherein the probing field of evanescent radiation is emitted from a sharpened metal tip instead of an aperture or gap. This sharpened tip, which is electrically and mechanically connected to a central electrode, extends through and beyond an aperture in an endwall of a microwave resonating device such as a microwave cavity resonator or a microwave stripline resonator. Since the field intensity at the tip increases as the tip sharpens, the total energy which is radiated from the tip and absorbed by the sample increases as the tip sharpens. The result is improved spatial resolution without sacrificing sensitivity.

  12. Earthquake-Ionosphere Coupling Processes

    NASA Astrophysics Data System (ADS)

    Kamogawa, Masashi

    an ionospheric phenomenon attributed to tsunami, termed tsunamigenic ionospheric hole (TIH) [Kakinami and Kamogwa et al., GRL, 2012]. After the TEC depression accompanying a monoperiodic variation with approximately 4-minute period as an acoustic resonance between the ionosphere and the solid earth, the TIH gradually recovered. In addition, geomagnetic pulsations with the periods of 150, 180 and 210 seconds were observed on the ground in Japan approximately 5 minutes after the mainshock. Since the variation with the period of 180 seconds was simultaneously detected at the magnetic conjugate of points of Japan, namely Australia, field aligned currents along the magnetic field line were excited. The field aligned currents might be excited due to E and F region dynamo current caused by acoustic waves originating from the tsunami. This result implies that a large earthquake generates seismogenic field aligned currents. Furthermore, monoperiodical geomagnetic oscillation pointing to the epicenter of which velocity corresponds to Rayleigh waves occurs. This may occur due to seismogenic arc-current in E region. Removing such magnetic oscillations from the observed data, clear tsunami dynamo effect was found. This result implies that a large EQ generates seismogenic field aligned currents, seismogenic arc-current and tsunami dynamo current which disturb geomagnetic field. Thus, we found the complex coupling process between a large EQ and an ionosphere from the results of Tohoku EQ.

  13. Active Thermal Extraction and Temperature Sensing of Near-field Thermal Radiation

    PubMed Central

    Ding, D.; Kim, T.; Minnich, A. J.

    2016-01-01

    Recently, we proposed an active thermal extraction (ATX) scheme that enables thermally populated surface phonon polaritons to escape into the far-field. The concept is based on a fluorescence upconversion process that also occurs in laser cooling of solids (LCS). Here, we present a generalized analysis of our scheme using the theoretical framework for LCS. We show that both LCS and ATX can be described with the same mathematical formalism by replacing the electron-phonon coupling parameter in LCS with the electron-photon coupling parameter in ATX. Using this framework, we compare the ideal efficiency and power extracted for the two schemes and examine the parasitic loss mechanisms. This work advances the application of ATX to manipulate near-field thermal radiation for applications such as temperature sensing and active radiative cooling. PMID:27595609

  14. Active Thermal Extraction and Temperature Sensing of Near-field Thermal Radiation.

    PubMed

    Ding, D; Kim, T; Minnich, A J

    2016-01-01

    Recently, we proposed an active thermal extraction (ATX) scheme that enables thermally populated surface phonon polaritons to escape into the far-field. The concept is based on a fluorescence upconversion process that also occurs in laser cooling of solids (LCS). Here, we present a generalized analysis of our scheme using the theoretical framework for LCS. We show that both LCS and ATX can be described with the same mathematical formalism by replacing the electron-phonon coupling parameter in LCS with the electron-photon coupling parameter in ATX. Using this framework, we compare the ideal efficiency and power extracted for the two schemes and examine the parasitic loss mechanisms. This work advances the application of ATX to manipulate near-field thermal radiation for applications such as temperature sensing and active radiative cooling. PMID:27595609

  15. Curved laser microjet in near field.

    PubMed

    Kotlyar, Victor V; Stafeev, Sergey S; Kovalev, Alexey A

    2013-06-20

    With the use of the finite-difference time-domain-based simulation and a scanning near-field optical microscope that has a metal cantilever tip, the diffraction of a linearly polarized plane wave of wavelength λ by a glass corner step of height 2λ is shown to generate a low divergence laser jet of a root-parabolic form: over a distance of 4.7λ on the optical axis, the beam path is shifted by 2.1λ. The curved laser jet of the FWHM length depth of focus=9.5λ has the diameter FWHM=1.94λ over the distance 5.5λ, and the intensity maximum is 5 times higher than the incident wave intensity. The discrepancy between the analytical and the experimental results amounts to 11%. PMID:23842153

  16. MOUNTAIN-SCALE COUPLED PROCESSES (TH/THC/THM)MODELS

    SciTech Connect

    Y.S. Wu

    2005-08-24

    This report documents the development and validation of the mountain-scale thermal-hydrologic (TH), thermal-hydrologic-chemical (THC), and thermal-hydrologic-mechanical (THM) models. These models provide technical support for screening of features, events, and processes (FEPs) related to the effects of coupled TH/THC/THM processes on mountain-scale unsaturated zone (UZ) and saturated zone (SZ) flow at Yucca Mountain, Nevada (BSC 2005 [DIRS 174842], Section 2.1.1.1). The purpose and validation criteria for these models are specified in ''Technical Work Plan for: Near-Field Environment and Transport: Coupled Processes (Mountain-Scale TH/THC/THM, Drift-Scale THC Seepage, and Drift-Scale Abstraction) Model Report Integration'' (BSC 2005 [DIRS 174842]). Model results are used to support exclusion of certain FEPs from the total system performance assessment for the license application (TSPA-LA) model on the basis of low consequence, consistent with the requirements of 10 CFR 63.342 [DIRS 173273]. Outputs from this report are not direct feeds to the TSPA-LA. All the FEPs related to the effects of coupled TH/THC/THM processes on mountain-scale UZ and SZ flow are discussed in Sections 6 and 7 of this report. The mountain-scale coupled TH/THC/THM processes models numerically simulate the impact of nuclear waste heat release on the natural hydrogeological system, including a representation of heat-driven processes occurring in the far field. The mountain-scale TH simulations provide predictions for thermally affected liquid saturation, gas- and liquid-phase fluxes, and water and rock temperature (together called the flow fields). The main focus of the TH model is to predict the changes in water flux driven by evaporation/condensation processes, and drainage between drifts. The TH model captures mountain-scale three-dimensional flow effects, including lateral diversion and mountain-scale flow patterns. The mountain-scale THC model evaluates TH effects on water and gas

  17. Surface Wave Multipath Signals in Near-Field Microwave Imaging

    PubMed Central

    Meaney, Paul M.; Shubitidze, Fridon; Fanning, Margaret W.; Kmiec, Maciej; Epstein, Neil R.; Paulsen, Keith D.

    2012-01-01

    Microwave imaging techniques are prone to signal corruption from unwanted multipath signals. Near-field systems are especially vulnerable because signals can scatter and reflect from structural objects within or on the boundary of the imaging zone. These issues are further exacerbated when surface waves are generated with the potential of propagating along the transmitting and receiving antenna feed lines and other low-loss paths. In this paper, we analyze the contributions of multi-path signals arising from surface wave effects. Specifically, experiments were conducted with a near-field microwave imaging array positioned at variable heights from the floor of a coupling fluid tank. Antenna arrays with different feed line lengths in the fluid were also evaluated. The results show that surface waves corrupt the received signals over the longest transmission distances across the measurement array. However, the surface wave effects can be eliminated provided the feed line lengths are sufficiently long independently of the distance of the transmitting/receiving antenna tips from the imaging tank floor. Theoretical predictions confirm the experimental observations. PMID:22566992

  18. Surface wave multipath signals in near-field microwave imaging.

    PubMed

    Meaney, Paul M; Shubitidze, Fridon; Fanning, Margaret W; Kmiec, Maciej; Epstein, Neil R; Paulsen, Keith D

    2012-01-01

    Microwave imaging techniques are prone to signal corruption from unwanted multipath signals. Near-field systems are especially vulnerable because signals can scatter and reflect from structural objects within or on the boundary of the imaging zone. These issues are further exacerbated when surface waves are generated with the potential of propagating along the transmitting and receiving antenna feed lines and other low-loss paths. In this paper, we analyze the contributions of multi-path signals arising from surface wave effects. Specifically, experiments were conducted with a near-field microwave imaging array positioned at variable heights from the floor of a coupling fluid tank. Antenna arrays with different feed line lengths in the fluid were also evaluated. The results show that surface waves corrupt the received signals over the longest transmission distances across the measurement array. However, the surface wave effects can be eliminated provided the feed line lengths are sufficiently long independently of the distance of the transmitting/receiving antenna tips from the imaging tank floor. Theoretical predictions confirm the experimental observations. PMID:22566992

  19. Near-field thermoacoustic tomography of small animals

    NASA Astrophysics Data System (ADS)

    Kellnberger, Stephan; Hajiaboli, Amir; Razansky, Daniel; Ntziachristos, Vasilis

    2011-06-01

    Near-field radiofrequency thermoacoustic (NRT) tomography is a new imaging method that was developed to mitigate limitations of conventional thermoacoustic imaging approaches, related to hard compromises between signal strength and spatial resolution. By utilizing ultrahigh-energy electromagnetic impulses at ~20 ns duration along with improved energy absorption coupling in the near-field, this method can deliver high-resolution images without compromising signal to noise ratio. NRT is a promising modality, offering cost-effectiveness and ease of implementation and it can be conveniently scaled to image small animals and humans. However, several of the performance metrics of the method are not yet documented. In this paper, we characterize the expected imaging performance via numerical simulations based on a finite-integration time-domain (FITD) technique and experiments using tissue mimicking phantoms and different biological samples. Furthermore, we show for the first time whole-body tomographic imaging results from mice, revealing clear anatomical details along with highly dissipative inclusions introduced for control. The best spatial resolution achieved for those experiments was 150 µm.

  20. Electrooptic sensor module fabrication for near-field intrabody communication

    NASA Astrophysics Data System (ADS)

    Furuya, Akinori; Sasaki, Ai-ichiro; Morimura, Hiroki; Kagami, Osamu; Shinagawa, Mitsuru

    2014-09-01

    In this paper, we describe how to obtain a low cost electrooptic (EO) sensor module for the mass production of near-field intrabody communication devices. In our previous study, we used a bulk cleavage technique to fabricate EO modulators without the need for any optical polishing or washing processes. In this study, we fabricated EO modulators as a miniaturized chip sensor without a base portion, and clarified the feasibility of assembling optical components by only a passive alignment technique with a compact housing.

  1. Near-field performance assessment for the Saltstone Disposal Facility

    SciTech Connect

    Seitz, R.R.; Dicke, C.A.; Walton, J.C.

    1993-12-31

    A near-field performance assessment (PA) was conducted for the Saltstone Disposal Facility (SDF) at the Savannah River Site in South Carolina. The analysis was conducted in four parts: general screening calculations, degradation calculations, and flow and transport through the fractured and nonfractured facility. Modeling approaches and example sensitivity analysis results from the simulations of the fractured facility are discussed. Design considerations that may not be apparent without addressing flow and transport through fractures and lessons learned during the process are also presented.

  2. Infrared near-field imaging and spectroscopy based on thermal or synchrotron radiation

    SciTech Connect

    Peragut, Florian; De Wilde, Yannick; Brubach, Jean-Blaise; Roy, Pascale

    2014-06-23

    We demonstrate the coupling of a scattering near-field scanning optical microscope combined with a Fourier transform infrared spectrometer. The set-up operates using either the near-field thermal emission from the sample itself, which is proportional to the electromagnetic local density of states, or with an external infrared synchrotron source, which is broadband and highly brilliant. We perform imaging and spectroscopy measurements with sub-wavelength spatial resolution in the mid-infrared range on surfaces made of silicon carbide and gold and demonstrate the capabilities of the two configurations for super-resolved near-field mid-infrared hyperspectral imaging and that the simple use of a properly chosen bandpass filter on the detector allows one to image the spatial distribution of materials with sub-wavelength resolution by studying the contrast in the near-field images.

  3. The Survey on Near Field Communication.

    PubMed

    Coskun, Vedat; Ozdenizci, Busra; Ok, Kerem

    2015-01-01

    Near Field Communication (NFC) is an emerging short-range wireless communication technology that offers great and varied promise in services such as payment, ticketing, gaming, crowd sourcing, voting, navigation, and many others. NFC technology enables the integration of services from a wide range of applications into one single smartphone. NFC technology has emerged recently, and consequently not much academic data are available yet, although the number of academic research studies carried out in the past two years has already surpassed the total number of the prior works combined. This paper presents the concept of NFC technology in a holistic approach from different perspectives, including hardware improvement and optimization, communication essentials and standards, applications, secure elements, privacy and security, usability analysis, and ecosystem and business issues. Further research opportunities in terms of the academic and business points of view are also explored and discussed at the end of each section. This comprehensive survey will be a valuable guide for researchers and academicians, as well as for business in the NFC technology and ecosystem. PMID:26057043

  4. The Survey on Near Field Communication

    PubMed Central

    Coskun, Vedat; Ozdenizci, Busra; Ok, Kerem

    2015-01-01

    Near Field Communication (NFC) is an emerging short-range wireless communication technology that offers great and varied promise in services such as payment, ticketing, gaming, crowd sourcing, voting, navigation, and many others. NFC technology enables the integration of services from a wide range of applications into one single smartphone. NFC technology has emerged recently, and consequently not much academic data are available yet, although the number of academic research studies carried out in the past two years has already surpassed the total number of the prior works combined. This paper presents the concept of NFC technology in a holistic approach from different perspectives, including hardware improvement and optimization, communication essentials and standards, applications, secure elements, privacy and security, usability analysis, and ecosystem and business issues. Further research opportunities in terms of the academic and business points of view are also explored and discussed at the end of each section. This comprehensive survey will be a valuable guide for researchers and academicians, as well as for business in the NFC technology and ecosystem. PMID:26057043

  5. Gold Coating of Fiber Tips in Near-Field Scanning Optical Microscopy

    NASA Technical Reports Server (NTRS)

    Vikram, Chandra S.; Witherow, William K.

    2000-01-01

    We report what is believed to be the first experimental demonstration of gold coating by a chemical baking process on tapered fiber tips used in near-field scanning optical microscopy. Many tips can be simultaneously coated.

  6. Tuning near-field enhancements on an off-resonance nanorod dimer via temporally shaped femtosecond laser

    NASA Astrophysics Data System (ADS)

    Du, Guangqing; Yang, Qing; Chen, Feng; Lu, Yu; Wu, Yanmin; Ou, Yan; Hou, Xun

    2015-11-01

    We theoretically investigated ultrafast thermal dynamics tuning of near-field enhancements on an off-resonance gold nanorod dimer via temporally shaped femtosecond (fs) laser double pulses. The nonequilibrium thermal excitation is self-consistently coupled into a near-field scattering model for exploring the ultrafast near-field enhancement effects. It is revealed that the near electric-field localized within the gold nanorod dimer can be largely promoted via optimizing the temporal separation and the pulse energy ratio of temporally shaped femtosecond laser double pulses. The results are explained as thermal dynamics manipulation of plasmon resonances in the nanorod dimer via tailoring temporally shaped femtosecond laser. This study provides basic understanding for tuning near-field properties on poorly fabricated metallic nano-structures via temporally shaped femtosecond laser, which can find potential applications in the fields such as fs super-resolution near-field imaging, near-field optical tweezers, and fs photothermal therapy.

  7. Coupled processes associated with nuclear waste repositories

    SciTech Connect

    Tsang, C.F.

    1987-01-01

    This book deals with coupled processes which affect a nuclear waste repository. While there are many descriptive accounts of environmental degradation resulting from various land uses, the author emphasizes the geomorphic processes responsible for such changes and the reasons why various reclamation practices are valuable in environmental management.

  8. Coupled transport processes in semipermeable media

    SciTech Connect

    Jacobsen, J.S.; Carnahan, C.L.

    1990-03-01

    The thermodynamics of irreversible processes leads to nonlinear governing equations for direct and coupled mass transport processes. Analytical solutions of linearized versions of these equations can be used to verify numerical solutions of the nonlinear equations under conditions such that nonlinear terms are relatively small. This report presents derivations of the analytical solutions for one-dimensional and axisymmetric geometries. 7 refs.

  9. Near-field imaging of optical antenna modes in the mid-infrared.

    PubMed

    Olmon, Robert L; Krenz, Peter M; Jones, Andrew C; Boreman, Glenn D; Raschke, Markus B

    2008-12-01

    Optical antennas can enhance the coupling between free-space propagating light and the localized excitation of nanoscopic light emitters or receivers, thus forming the basis of many nanophotonic applications. Their functionality relies on an understanding of the relationship between the geometric parameters and the resulting near-field antenna modes. Using scattering-type scanning near-field optical microscopy (s-SNOM) with interferometric homodyne detection, we investigate the resonances of linear Au wire antennas designed for the mid-IR by probing specific vector near-field components. A simple effective wavelength scaling is observed for single wires with lambda(eff) = lambda /(2.0+/- 0.2), specific to the geometric and material parameters used. The disruption of the coherent current oscillation by introducing a gap gives rise to an effective multipolar mode for the two near-field coupled segments. Using antenna theory and numerical electrodynamics simulations two distinct coupling regimes are considered that scale with gap width or reactive near-field decay length, respectively. The results emphasize the distinct antenna behavior at optical frequencies compared to impedance matched radio frequency (RF) antennas and provide experimental confirmation of theoretically predicted scaling laws at optical frequencies. PMID:19065168

  10. Far-field subwavelength imaging with near-field resonant metalens scanning at microwave frequencies

    PubMed Central

    Wang, Ren; Wang, Bing-Zhong; Gong, Zhi-Shuang; Ding, Xiao

    2015-01-01

    A method for far-field subwavelength imaging at microwave frequencies using near-field resonant metalens scanning is proposed. The resonant metalens is composed of switchable split-ring resonators (SRRs). The on-SRR has a strong magnetic coupling ability and can convert evanescent waves into propagating waves using the localized resonant modes. In contrast, the off-SRR cannot achieve an effective conversion. By changing the switch status of each cell, we can obtain position information regarding the subwavelength source targets from the far field. Because the spatial response and Green’s function do not need to be measured and evaluated and only a narrow frequency band is required for the entire imaging process, this method is convenient and adaptable to various environment. This method can be used for many applications, such as subwavelength imaging, detection, and electromagnetic monitoring, in both free space and complex environments. PMID:26053074

  11. Vibrational near-field mapping of planar and buried three-dimensional plasmonic nanostructures.

    PubMed

    Dregely, Daniel; Neubrech, Frank; Duan, Huigao; Vogelgesang, Ralf; Giessen, Harald

    2013-01-01

    Nanoantennas confine electromagnetic fields at visible and infrared wavelengths to volumes of only a few cubic nanometres. Assessing their near-field distribution offers fundamental insight into light-matter coupling and is of special interest for applications such as radiation engineering, attomolar sensing and nonlinear optics. Most experimental approaches to measure near-fields employ either diffraction-limited far-field methods or intricate near-field scanning techniques. Here, using diffraction-unlimited far-field spectroscopy in the infrared, we directly map the intensity of the electric field close to plasmonic nanoantennas. We place a patch of probe molecules with 10 nm accuracy at different locations in the near-field of a resonant antenna and extract the molecular vibrational excitation. We map the field intensity along a dipole antenna and gap-type antennas. Moreover, this method is able to assess the near-field intensity of complex buried plasmonic structures. We demonstrate this by measuring for the first time the near-field intensity of a three-dimensional plasmonic electromagnetically induced transparency structure. PMID:23892519

  12. Dynamic near-field optical interaction between oscillating nanomechanical structures

    PubMed Central

    Ahn, Phillip; Chen, Xiang; Zhang, Zhen; Ford, Matthew; Rosenmann, Daniel; Jung, II Woong; Sun, Cheng; Balogun, Oluwaseyi

    2015-01-01

    Near-field optical techniques exploit light-matter interactions at small length scales for mechanical sensing and actuation of nanomechanical structures. Here, we study the optical interaction between two mechanical oscillators—a plasmonic nanofocusing probe-tip supported by a low frequency cantilever, and a high frequency nanomechanical resonator—and leverage their interaction for local detection of mechanical vibrations. The plasmonic nanofocusing probe provides a confined optical source to enhance the interaction between the two oscillators. Dynamic perturbation of the optical cavity between the probe-tip and the resonator leads to nonlinear modulation of the scattered light intensity at the sum and difference of their frequencies. This double-frequency demodulation scheme is explored to suppress unwanted background and to detect mechanical vibrations with a minimum detectable displacement sensitivity of 0.45 pm/Hz1/2, which is limited by shot noise and electrical noise. We explore the demodulation scheme for imaging the bending vibration mode shape of the resonator with a lateral spatial resolution of 20 nm. We also demonstrate the time-resolved aspect of the local optical interaction by recording the ring-down vibrations of the resonator at frequencies of up to 129 MHz. The near-field optical technique is promising for studying dynamic mechanical processes in individual nanostructures. PMID:26014599

  13. Dynamic near-field optical interaction between oscillating nanomechanical structures

    SciTech Connect

    Ahn, Phillip; Chen, Xiang; Zhang, Zhen; Ford, Matthew; Rosenmann, Daniel; Jung, II Woong; Sun, Cheng; Balogun, Oluwaseyi

    2015-05-27

    Near-field optical techniques exploit light-matter interactions at small length scales for mechanical sensing and actuation of nanomechanical structures. Here, we study the optical interaction between two mechanical oscillators—a plasmonic nanofocusing probe-tip supported by a low frequency cantilever, and a high frequency nanomechanical resonator—and leverage their interaction for local detection of mechanical vibrations. The plasmonic nanofocusing probe provides a confined optical source to enhance the interaction between the two oscillators. Dynamic perturbation of the optical cavity between the probe-tip and the resonator leads to nonlinear modulation of the scattered light intensity at the sum and difference of their frequencies. This double-frequency demodulation scheme is explored to suppress unwanted background and to detect mechanical vibrations with a minimum detectable displacement sensitivity of 0.45pm/Hz1/2, which is limited by shot noise and electrical noise. We explore the demodulation scheme for imaging the bending vibration mode shape of the resonator with a lateral spatial resolution of 20nm. We also demonstrate the time-resolved aspect of the local optical interaction by recording the ring-down vibrations of the resonator at frequencies of up to 129MHz. The near-field optical technique is promising for studying dynamic mechanical processes in individual nanostructures.

  14. Dynamic near-field optical interaction between oscillating nanomechanical structures

    DOE PAGESBeta

    Ahn, Phillip; Chen, Xiang; Zhang, Zhen; Ford, Matthew; Rosenmann, Daniel; Jung, II Woong; Sun, Cheng; Balogun, Oluwaseyi

    2015-05-27

    Near-field optical techniques exploit light-matter interactions at small length scales for mechanical sensing and actuation of nanomechanical structures. Here, we study the optical interaction between two mechanical oscillators—a plasmonic nanofocusing probe-tip supported by a low frequency cantilever, and a high frequency nanomechanical resonator—and leverage their interaction for local detection of mechanical vibrations. The plasmonic nanofocusing probe provides a confined optical source to enhance the interaction between the two oscillators. Dynamic perturbation of the optical cavity between the probe-tip and the resonator leads to nonlinear modulation of the scattered light intensity at the sum and difference of their frequencies. This double-frequencymore » demodulation scheme is explored to suppress unwanted background and to detect mechanical vibrations with a minimum detectable displacement sensitivity of 0.45pm/Hz1/2, which is limited by shot noise and electrical noise. We explore the demodulation scheme for imaging the bending vibration mode shape of the resonator with a lateral spatial resolution of 20nm. We also demonstrate the time-resolved aspect of the local optical interaction by recording the ring-down vibrations of the resonator at frequencies of up to 129MHz. The near-field optical technique is promising for studying dynamic mechanical processes in individual nanostructures.« less

  15. Assessment of Near-Field Sonic Boom Simulation Tools

    NASA Technical Reports Server (NTRS)

    Casper, J. H.; Cliff, S. E.; Thomas, S. D.; Park, M. A.; McMullen, M. S.; Melton, J. E.; Durston, D. A.

    2008-01-01

    A recent study for the Supersonics Project, within the National Aeronautics and Space Administration, has been conducted to assess current in-house capabilities for the prediction of near-field sonic boom. Such capabilities are required to simulate the highly nonlinear flow near an aircraft, wherein a sonic-boom signature is generated. There are many available computational fluid dynamics codes that could be used to provide the near-field flow for a sonic boom calculation. However, such codes have typically been developed for applications involving aerodynamic configuration, for which an efficiently generated computational mesh is usually not optimum for a sonic boom prediction. Preliminary guidelines are suggested to characterize a state-of-the-art sonic boom prediction methodology. The available simulation tools that are best suited to incorporate into that methodology are identified; preliminary test cases are presented in support of the selection. During this phase of process definition and tool selection, parallel research was conducted in an attempt to establish criteria that link the properties of a computational mesh to the accuracy of a sonic boom prediction. Such properties include sufficient grid density near shocks and within the zone of influence, which are achieved by adaptation and mesh refinement strategies. Prediction accuracy is validated by comparison with wind tunnel data.

  16. Coupling environmental models and geospatial data processing

    NASA Astrophysics Data System (ADS)

    Brandmeyer, Jo Ellen

    2000-10-01

    This research investigated geospatial functions for solving environmental problems from the perspective of the environmental modeler. Its purpose is to better understand the different approaches to coupling complex models and geospatial data processing, plus the implications for the coupled system. To this end, various coupling methodologies were systematically explored using a geographic information system (GIS) and an emissions processor (SMOKE) for air quality models (AQMs). SMOKE converts an emissions inventory into the format required by an AQM. A GIS creates a file describing the spatial distribution of emissions among the cells in a modeling domain. To demonstrate advantages of a coupled GIS---environmental model system, two methods of spatially distributing on-road mobile emissions to cells were examined. The existing method calculates emissions for each road class, but distributes emissions to the cells using population density. For the new method a GIS builds road density by class and then distributes the emissions using road density. Comparing these methods reveals a significantly different spatial pattern of emissions. Next, various model-coupling methodologies were analyzed, revealing numerous coupling approaches, some of which were categorized in the literature. Critiquing these categorizations while comparing them with documented implementations led to the development of a new coupling hierarchy. The properties of each hierarchical level are discussed with the advantages and limitations of each design. To successfully couple models, the spatial and temporal scales of all models in the coupled system and the spatiotemporal extents of the data must be reconciled. Finally, a case study demonstrated methodologies for coupling SMOKE and a GIS. One methodology required a new approach utilizing dynamically linked libraries. Consequently, emissions were processed using SMOKE from a GIS. Also, a new method of converting data from netCDF files into a database

  17. Experimental characterization of Fabry-Perot resonances of magnetostatic volume waves in near-field metamaterials

    NASA Astrophysics Data System (ADS)

    Chabalko, Matthew J.; Ricketts, David S.

    2015-02-01

    In this work, we report on the experimental demonstration of magnetoquasistatic volume wave resonances in a 2-dimensional near field metamaterial (MM). Previous works have described only theoretically the magnetostatic waves in near field MMs and have reported peaks and valleys in the mutual coupling of MM enhanced wireless power transfer that they have attributed to Fabry-Perot resonances, however, neither has been experimentally measured nor characterized. We report on the direct magnetic field measurement of magnetostatic volume waves in a 2D near-field MM and show that the periodic peaks and valleys in mutual coupling observed previously are indeed due to a Fabry-Perot oscillation. In addition, we show that these resonances can be predicted from experimentally extracted permeability and the dimensions of the system.

  18. A unidirectional subwavelength focusing near-field plate

    SciTech Connect

    Imani, Mohammadreza F.; Grbic, Anthony

    2014-01-28

    Near-field plates consist of non-periodically patterned surfaces that can overcome the diffraction limit and confine electromagnetic fields to subwavelength dimensions. Previous near-field plates experimentally demonstrated extreme field tailoring capabilities. However, their performance suffered from radiation/reflection in undesired directions, those other than the subwavelength focus. This issue can limit the practical use of near-field plates. In this paper, we address this issue by designing a unidirectional near-field plate that can form a subwavelength focal pattern, while suppressing the field radiated/reflected in other directions. The design and operation of the proposed unidirectional near-field plate are verified through full-wave simulation. The unidirectional near-field plate may find application in high resolution imaging and probing, high density data storage, and wireless power transfer systems. As an example, its utility as a high resolution probe is demonstrated through full-wave electromagnetic simulation.

  19. DRIFT-SCALE COUPLED PROCESSES (DST AND TH SEEPAGE) MODELS

    SciTech Connect

    J.T. Birkholzer; S. Mukhopadhyay

    2005-01-13

    The purpose of this report is to document drift-scale modeling work performed to evaluate the thermal-hydrological (TH) behavior in Yucca Mountain fractured rock close to waste emplacement drifts. The heat generated by the decay of radioactive waste results in rock temperatures elevated from ambient for thousands of years after emplacement. Depending on the thermal load, these temperatures are high enough to cause boiling conditions in the rock, giving rise to water redistribution and altered flow paths. The predictive simulations described in this report are intended to investigate fluid flow in the vicinity of an emplacement drift for a range of thermal loads. Understanding the TH coupled processes is important for the performance of the repository because the thermally driven water saturation changes affect the potential seepage of water into waste emplacement drifts. Seepage of water is important because if enough water gets into the emplacement drifts and comes into contact with any exposed radionuclides, it may then be possible for the radionuclides to be transported out of the drifts and to the groundwater below the drifts. For above-boiling rock temperatures, vaporization of percolating water in the fractured rock overlying the repository can provide an important barrier capability that greatly reduces (and possibly eliminates) the potential of water seeping into the emplacement drifts. In addition to this thermal process, water is inhibited from entering the drift opening by capillary forces, which occur under both ambient and thermal conditions (capillary barrier). The combined barrier capability of vaporization processes and capillary forces in the near-field rock during the thermal period of the repository is analyzed and discussed in this report.

  20. Drift-Scale Coupled Processes (DST and TH Seepage) Models

    SciTech Connect

    J. Birkholzer; S. Mukhopadhyay

    2004-09-29

    The purpose of this report is to document drift-scale modeling work performed to evaluate the thermal-hydrological (TH) behavior in Yucca Mountain fractured rock close to waste emplacement drifts. The heat generated by the decay of radioactive waste results in rock temperatures elevated from ambient for thousands of years after emplacement. Depending on the thermal load, these temperatures are high enough to cause boiling conditions in the rock, giving rise to water redistribution and altered flow paths. The predictive simulations described in this report are intended to investigate fluid flow in the vicinity of an emplacement drift for a range of thermal loads. Understanding the TH coupled processes is important for the performance of the repository because the thermally driven water saturation changes affect the potential seepage of water into waste emplacement drifts. Seepage of water is important because if enough water gets into the emplacement drifts and comes into contact with any exposed radionuclides, it may then be possible for the radionuclides to be transported out of the drifts and to the groundwater below the drifts. For above-boiling rock temperatures, vaporization of percolating water in the fractured rock overlying the repository can provide an important barrier capability that greatly reduces (and possibly eliminates) the potential of water seeping into the emplacement drifts. In addition to this thermal process, water is inhibited from entering the drift opening by capillary forces, which occur under both ambient and thermal conditions (capillary barrier). The combined barrier capability of vaporization processes and capillary forces in the near-field rock during the thermal period of the repository is analyzed and discussed in this report.

  1. Near-field imaging techniques for surface inspection

    NASA Astrophysics Data System (ADS)

    Dannenberg, Florian; Hahlweg, Cornelius; Pescoller, Lukas; Zhao, Wenjing

    2014-09-01

    Following the recent work on the characterization of flexo-printing plates a concept for inspection of glossy surfaces using a defined out of focus image of the surface under parallel illumination is presented, which in principle represents a near field distribution of the reflection function of the surface. The image turns out to be equivalent to a focussed shadowgraph as used for the investigation of processes in transparent media. Beside the plain 'reflected shadow imaging' several degrees of freedom can be exploited for configuration of the feature emphasis. The method is especially interesting for the quality control of printed matter. In the paper the definition of the system, the mechanism of the imaging process and its relation to the real image of the surface itself are considered. Further, questions of resolution, extractable features and extended applications are discussed.

  2. Induction coupled thermomagnetic processing: A disruptive technology

    DOE PAGESBeta

    Ahmad, Aquil; Mackiewicz-Ludtka, Gail; Pfaffmann, George; Ludtka, Gerard Michael

    2016-06-01

    Here, one of the major goals of the U.S. Department of Energy (DoE) is to achieve energy savings with a corresponding reduction in the carbon footprint. With this in mind, the DoE sponsored the Induction Coupled Thermomagnetic Processing (ITMP) project with major partners Eaton Corp., Ajax Tocco Magnethermic, and Oak Ridge National Laboratory (ORNL) to evaluate the viability of processing metals in a strong magnetic field.

  3. CAD/CAM-coupled image processing systems

    NASA Astrophysics Data System (ADS)

    Ahlers, Rolf-Juergen; Rauh, W.

    1990-08-01

    Image processing systems have found wide application in industry. For most computer integrated manufacturing faci- lities it is necessary to adapt these systems thus that they can automate the interaction with and the integration of CAD and CAM Systems. In this paper new approaches will be described that make use of the coupling of CAD and image processing as well as the automatic generation of programmes for the machining of products.

  4. Near field interactions in terahertz metamaterials

    NASA Astrophysics Data System (ADS)

    Keiser, George R.

    Terahertz (THz) frequencies comprise the portion of the electromagnetic spectrum more energetic than microwaves, but less energetic than infrared light. The THz band presents many opportunities for condensed matter physics and optics engineering. From the physics perspective, advances in the generation and detection of THz radiation have opened the door for spectroscopic studies of a range of solid-state phenomena that manifest at THz frequencies. From an engineering perspective, THz frequencies are an under-used spectral region, ripe for the development of new devices. In both cases, the challenge for researchers is to overcome a lack of sources, detectors, and optics for THz light, termed the THz Gap. Metamaterials (MMs), composite structures with engineered index of refraction, n, and impedance, Z, provide one path towards realizing THz optics. MMs are an ideal platform for the design of local EM field distributions, and far-field optical properties. This is especially true at THz frequencies, where fabrication of inclusions is easily accomplished with photolithography. Historically, MM designs have been based around static configurations of resonant inclusions that work only in a narrow frequency band, limiting applications. Broadband and tunable MMs are needed to overcome this limit. This dissertation focuses on creating tunable and controllable MM structures through the manipulation of electromagnetic interactions between MM inclusions. We introduce three novel MM systems. Each system is studied computationally with CST-Studio, and experimentally via THz spectroscopy. First, we look at the tunable transmission spectrum of two coupled split ring resonators (SRRs) with different resonant frequencies. We show that introducing a lateral displacement between the two component resonators lowers the electromagnetic coupling between the SRRs, activating a new resonance. Second, we study an SRR array, coupled to a non-resonant closed ring array. We show that lowering

  5. Nanospectrofluorometry inside single living cell by scanning near-field optical microscopy

    NASA Astrophysics Data System (ADS)

    Lei, F. H.; Shang, G. Y.; Troyon, M.; Spajer, M.; Morjani, H.; Angiboust, J. F.; Manfait, M.

    2001-10-01

    Near-field fluorescence spectra with subdiffraction limit spatial resolution have been taken in the proximity of mitochondrial membrane inside breast adenocarcinoma cells (MCF7) treated with the fluorescent dye (JC-1) by using a scanning near-field optical microscope coupled with a confocal laser microspectrofluorometer. The probe-sample distance control is based on a piezoelectric bimorph shear force sensor having a static spring constant k=5 μN/nm and a quality factor Q=40 in a physiological medium of viscosity η=1.0 cp. The sensitivity of the force sensor has been tested by imaging a MCF7 cell surface.

  6. Heat flux splitter for near-field thermal radiation

    SciTech Connect

    Ben-Abdallah, P.; Belarouci, A.; Frechette, L.; Biehs, S.-A.

    2015-08-03

    We demonstrate the possibility to efficiently split the near-field heat flux exchanged between graphene nano-disks by tuning their doping. This result paves the way for the development of an active control of propagation directions for heat fluxes exchanged in the near field throughout integrated nanostructured networks.

  7. Coupled transport processes in semipermeable media

    SciTech Connect

    Jacobsen, J.S.; Carnahan, C.L.

    1990-04-01

    A numerical simulator has been developed to investigate the effects of coupled processes on heat and mass transport in semipermeable media. The governing equations on which the simulator is based were derived using the thermodynamics of irreversible processes. The equations are nonlinear and have been solved numerically using the n-dimensional Newton's method. As an example of an application, the numerical simulator has been used to investigate heat and solute transport in the vicinity of a heat source buried in a saturated clay-like medium, in part to study solute transport in bentonite packing material surrounding a nuclear waste canister. The coupled processes considered were thermal filtration, thermal osmosis, chemical osmosis and ultrafiltration. In the simulations, heat transport by coupled processes was negligible compared to heat conduction, but pressure and solute migration were affected. Solute migration was retarded relative to the uncoupled case when only chemical osmosis was considered. When both chemical osmosis and thermal osmosis were included, solute migration was enhanced. 18 refs., 20 figs.

  8. Mesoscopic near-field radiative heat transfer at low temperatures

    NASA Astrophysics Data System (ADS)

    Maasilta, Ilari; Geng, Zhuoran; Chaudhuri, Saumyadip; Koppinen, Panu

    2015-03-01

    Near-field radiative heat transfer has mostly been discussed at room temperatures and/or macroscopic scale geometries. Here, we discuss our recent theoretical and experimental advances in understanding near-field transfer at ultra-low temperatures below 1K. As the thermal wavelengths increase with lowering temperature, we show that with sensitive tunnel junction bolometers it is possible to study near-field transfer up to distances ~ 10 μm currently, even though the power levels are low. In addition, these type of experiments correspond to the extreme near-field limit, as the near-field region starts at ~ mm distances at 0.1 K, and could have theoretical power enhancement factors of the order of 1010. Preliminary results on heat transfer between two parallel metallic wires are presented. We also comment on possible areas were such heat transfer might be relevant, such as densely packed arrays of low-temperature detectors.

  9. Modeling of Inner Magnetosphere Coupling Processes

    NASA Technical Reports Server (NTRS)

    Khazanov, George V.

    2011-01-01

    The Ring Current (RC) is the biggest energy player in the inner magnetosphere. It is the source of free energy for Electromagnetic Ion Cyclotron (EMIC) wave excitation provided by a temperature anisotropy of RC ions, which develops naturally during inward E B convection from the plasmasheet. The cold plasmasphere, which is under the strong influence of the magnetospheric electric field, strongly mediates the RC-EMIC wave-particle-coupling process and ultimately becomes part of the particle and energy interplay. On the other hand, there is a strong influence of the RC on the inner magnetospheric electric and magnetic field configurations and these configurations, in turn, are important to RC dynamics. Therefore, one of the biggest needs for inner magnetospheric research is the continued progression toward a coupled, interconnected system with the inclusion of nonlinear feedback mechanisms between the plasma populations, the electric and magnetic fields, and plasma waves. As we clearly demonstrated in our studies, EMIC waves strongly interact with electrons and ions of energies ranging from approx.1 eV to approx.10 MeV, and that these waves strongly affect the dynamics of resonant RC ions, thermal electrons and ions, and the outer RB relativistic electrons. As we found, the rate of ion and electron scattering/heating in the Earth's magnetosphere is not only controlled by the wave intensity-spatial-temporal distribution but also strongly depends on the spectral distribution of the wave power. The latter is also a function of the plasmaspheric heavy ion content, and the plasma density and temperature distributions along the magnetic field lines. The above discussion places RC-EMIC wave coupling dynamics in context with inner magnetospheric coupling processes and, ultimately, relates RC studies with plasmaspheric and Superthermal Electrons formation processes as well as with outer RB physics.

  10. Coupled transport processes in semipermeable media

    SciTech Connect

    Carnahan, C.L.; Jacobsen, J.S.

    1990-04-01

    The thermodynamics of irreversible processes (TTIP) is used to derive governing equations and phenomenological equations for transport processes and chemical reactions in water-saturated semipermeable media. TTIP is based on three fundamental postulates. The first postulate, the assumption of local equilibrium, allows the formulation of balance equations for entropy. These equations are the bases for the derivation of governing equations for the thermodynamic variables, temperature, pressure, and composition. The governing equations involve vector fluxes of heat and mass and scalar rates of chemical reactions; in accordance with the second postulate of TTIP, these fluxes and rates are related, respectively, to all scalar driving forces (gradients of thermodynamic variables) acting within the system. The third postulate of TTIP states equality (the Onsager reciprocal relations) between certain of the phenomenological coefficients relating forces and fluxes. The description by TTIP of a system undergoing irreversible processes allows consideration of coupled transport processes such as thermal osmosis, chemical osmosis, and ultrafiltration. The coupled processes can make significant contributions to flows of mass and energy in slightly permeable, permselective geological materials such as clays and shales.

  11. Atomic force microscope based near-field imaging for probing cell surface interactions

    NASA Astrophysics Data System (ADS)

    Amini, Sina

    Near-membrane and trans-membrane proteins and their interactions with the extracellular matrix (ECM) can yield valuable information about cell dynamics. However, advances in the field of nanoscale cellular processes have been hindered, in part, due to limits imposed by current technology. In this work, a novel evanescent field (EF) imaging technique is designed, modeled, created and tested for near-field imaging in the apical surface of cells. This technique and Forster resonance energy transfer (FRET) were used to investigate interactions between integrins on the cell surface and the ECM protein, fibronectin. The goal was to monitor changes in the integrin density at the cell surface as a function of clustering after binding to fibronectin on the microsphere surface. For the EF technique, quantum dot (QD)-embedded polystyrene microspheres were used to couple light into whispering gallery modes (WGMs) inside the microspheres; the resulting EF at the surface of the microsphere was used as a near-field excitation source with ~50 nm axial resolution for exciting fluorescently-labeled integrins. For FRET measurements (~10 nm axial resolution), QDs (donors) were coated on the surface of microspheres and energy transfer to red fluorescent protein (RFP)-integrin constructs (acceptors) studied. In both techniques, the QD-modified microspheres were mounted on atomic force microscope (AFM) cantilevers, functionalized with fibronectin, and brought into contact with fluorescently-labeled HeLa or vascular smooth muscle (VSM) cells. The results obtained from both methods show the clustering and activity of the integrins and are in good agreement with each other. Amsterdam discrete dipole approximation (ADDA) was used to study the effects of inhomogeneous surrounding refractive index on the quality factor and position of the WGMs due to the attachment of a microsphere to an AFM cantilever. WGMs of various QD-embedded microspheres mounted on AFM cantilevers were experimentally

  12. Synthesis report on thermally driven coupled processes

    SciTech Connect

    Hardin, E.L.

    1997-10-15

    The main purpose of this report is to document observations and data on thermally coupled processes for conditions that are expected to occur within and around a repository at Yucca Mountain. Some attempt is made to summarize values of properties (e.g., thermal properties, hydrologic properties) that can be measured in the laboratory on intact samples of the rock matrix. Variation of these properties with temperature, or with conditions likely to be encountered at elevated temperature in the host rock, is of particular interest. However, the main emphasis of this report is on direct observation of thermally coupled processes at various scales. Direct phenomenological observations are vitally important in developing and testing conceptual models. If the mathematical implementation of a conceptual model predicts a consequence that is not observed, either (1) the parameters or the boundary conditions used in the calculation are incorrect or (2) the conceptual basis of the model does not fit the experiment; in either case, the model must be revised. For example, the effective continuum model that has been used in thermohydrology studies combines matrix and fracture flow in a way that is equivalent to an assumption that water is imbibed instantaneously from fractures into adjacent, partially saturated matrix. Based on this approximation, the continuum-flow response that is analogous to fracture flow will not occur until the effective continuum is almost completely saturated. This approximation is not entirely consistent with some of the experimental data presented in this report. This report documents laboratory work and field studies undertaken in FY96 and FY97 to investigate thermally coupled processes such as heat pipes and fracture-matrix coupling. In addition, relevant activities from past years, and work undertaken outside the Yucca Mountain project are summarized and discussed. Natural and artificial analogs are also discussed to provide a convenient source of

  13. Near field wireless power transfer using curved relay resonators for extended transfer distance

    NASA Astrophysics Data System (ADS)

    Zhu, D.; Clare, L.; Stark, B. H.; Beeby, S. P.

    2015-12-01

    This paper investigates the performance of a near field wireless power transfer system that uses curved relay resonator to extend transfer distance. Near field wireless power transfer operates based on the near-field electromagnetic coupling of coils. Such a system can transfer energy over a relatively short distance which is of the same order of dimensions of the coupled coils. The energy transfer distance can be increased using flat relay resonators. Recent developments in printing electronics and e-textiles have seen increasing demand of embedding electronics into fabrics. Near field wireless power transfer is one of the most promising methods to power electronics on fabrics. The concept can be applied to body-worn textiles by, for example, integrating a transmitter coil into upholstery, and a flexible receiver coil into garments. Flexible textile coils take on the shape of the supporting materials such as garments, and therefore curved resonator and receiver coils are investigated in this work. Experimental results showed that using curved relay resonator can effectively extend the wireless power transfer distance. However, as the curvature of the coil increases, the performance of the wireless power transfer, especially the maximum received power, deteriorates.

  14. Near-field fluorescence thermometry using highly efficient triple-tapered near-field optical fiber probe

    NASA Astrophysics Data System (ADS)

    Fujii, T.; Taguchi, Y.; Saiki, T.; Nagasaka, Y.

    2012-12-01

    A novel local temperature measurement method using fluorescence near-field optics thermal nanoscopy (Fluor-NOTN) has been developed. Fluor-NOTN enables nanoscale temperature measurement in situ by detecting the temperature-dependent fluorescence lifetime of CdSe quantum dots (QDs). In this paper, we report a novel triple-tapered near-field optical fiber probe that can increase the temperature measurement sensitivity of Fluor-NOTN. The performance of the proposed probe was numerically evaluated by the finite difference time domain method. Due to improvements in both the throughput and collection efficiency of near-field light, the sensitivity of the proposed probe was 1.9 times greater than that of typical double-tapered probe. The proposed shape of the triple-tapered core was successfully fabricated utilizing a geometrical model. The detected signal intensity of dried layers of QDs was greater by more than two orders than that of auto-fluorescence from the fiber core. In addition, the near-field fluorescence lifetime of the QDs and its temperature dependence were successfully measured by the fabricated triple-tapered near-field optical fiber probe. These measurement results verified the capability of the proposed triple-tapered near-field optical fiber probe to improve the collection efficiency of near-field fluorescence.

  15. Near-Field Scanning Optical Microscopy and Raman Microscopy.

    NASA Astrophysics Data System (ADS)

    Harootunian, Alec Tate

    1987-09-01

    Both a one dimensional near-field scanning optical microscope and Raman microprobe were constructed. In near -field scanning optical microscopy (NSOM) a subwavelength aperture is scanned in the near-field of the object. Radiation transmitted through the aperture is collected to form an image as the aperture scans over the object. The resolution of an NSOM system is essentially wavelength independent and is limited by the diameter of the aperture used to scan the object. NSOM was developed in an effort to provide a nondestructive in situ high spatial resolution probe while still utilizing photons at optical wavelengths. The Raman microprobe constructed provided vibrational Raman information with spatial resolution equivalent that of a conventional diffraction limited microscope. Both transmission studies and near-field diffration studies of subwavelength apertures were performed. Diffraction theories for a small aperture in an infinitely thin conducting screen, a slit in a thick conducting screen, and an aperture in a black screen were examined. All three theories indicate collimation of radiation to the size to the size of the subwavelength aperture or slit in the near-field. Theoretical calculations and experimental results indicate that light transmitted through subwavelength apertures is readily detectable. Light of wavelength 4579 (ANGSTROM) was transmitted through apertures with diameters as small as 300 (ANGSTROM). These studies indicate the feasibility of constructing an NSOM system. One dimensional transmission and fluorescence NSOM systems were constructed. Apertures in the tips of metallized glass pipettes width inner diameters of less than 1000 (ANGSTROM) were used as a light source in the NSOM system. A tunneling current was used to maintain the aperture position in the near-field. Fluorescence NSOM was demonstrated for the first time. Microspectroscopic and Raman microscopic studies of turtle cone oil droplets were performed. Both the Raman vibrational

  16. Non-contact transportation using near-field acoustic levitation

    PubMed

    Ueha; Hashimoto; Koike

    2000-03-01

    Near-field acoustic levitation, where planar objects 10 kg in weight can levitate stably near the vibrating plate, is successfully applied both to non-contact transportation of objects and to a non-contact ultrasonic motor. Transporting apparatuses and an ultrasonic motor have been fabricated and their characteristics measured. The theory of near-field acoustic levitation both for a piston-like sound source and a flexural vibration source is also briefly described. PMID:10829622

  17. Near-field scanning optical microscopy investigations of conjugated polymers

    NASA Astrophysics Data System (ADS)

    Dearo, Jessie Ann

    The Near-Field Scanning Optical Microscopy (NSOM) studies of novel, optically active, conjugated polymers are presented. NSOM is a relatively new technique which produces super resolution (˜50--100 nm) optical images simultaneously with topography. The conjugated polymer poly(p-phenylene vinylene) (PPV) and derivatives of PPV are organic semiconductor-like materials with interesting and unique optical properties. Derivatives of PPV have been used in LEDs and have potential in other optoelectronic devices. NSOM provides a tool for investigation of the photoluminescence, absorption/reflection, photo-dynamics and photoconductivity of films of PPV and PPV derivatives on the length scale that these properties are fundamentally defined. The NSOM experiments have revealed mesoscale domains (˜100 nm) of varying photoluminescence emission and average molecular order in drop cast films of PPV. NSOM of stretch-oriented PPV have shown domains of perpendicular molecular orientation with low photoluminescence emission. Near-field photoconductivity experiments of stretch-oriented PPV have correlated the mesoscale topography with the photoconductivity properties of the polymer. NSOM experiments of films of poly(2-methoxy, 5-(2'-(ethyl(hexyloxy)-p-phenylene vinylene) (MEH-PPV) have shown that there is mesoscale spatial inhomogeneity in the photo-oxidation process which reduces photoluminescence emission. NSOM has also been used to create nanoscale photo-patterning in MEH-PPV films. The NSOM experiments of blended films of MEH-PPV in polystyrene have shown mesoscale phase separation directly correlated to variations in the optical properties of the film. Derivatives of PPV, stretch-oriented in polyethylene, show photoluminescence intensity variations perpendicular and parallel to the stretch-direction correlated to topography features. As a complement to the NSOM studies of conjugated polymers, single polymer molecule experiments of MEH-PPV are also presented. The

  18. Near-field ptychography using lateral and longitudinal shifts

    NASA Astrophysics Data System (ADS)

    Robisch, A.-L.; Kröger, K.; Rack, A.; Salditt, T.

    2015-07-01

    Image reconstruction of in-line holography depends crucially on the probing wave front used to illuminate an object. Aberrations inherent to the illumination can mix with the features imposed by the object. Conventional raw data processing methods rely on the division of the measured hologram by the intensity profile of the probe and are not able to fully eliminate artifacts caused by the illumination. Here we present a generalized ptychography approach to simultaneously reconstruct object and probe in the optical near-field. Combining the ideas of ptychographic lateral shifts of the object with variations of the propagation distance by longitudinal shifts, simultaneous reconstruction of object and probe was achieved equally well for a highly aberrated and a mildly disturbed probe without the need for an additional wave front diffuser. The method overcomes the image deterioration by a non-ideal probe and at the same time any restrictions due to linearization of the object’s transmission function or the Fresnel propagator. The method is demonstrated experimentally using visible light and hard x-rays, in both parallel beam and cone beam geometry, which is relevant for high resolution x-ray imaging. It also opens up a new approach to characterize extended wave fronts by phase retrieval.

  19. A novel mathematical model for controllable near-field electrospinning

    SciTech Connect

    Ru, Changhai E-mail: luojun@shu.edu.cn; Chen, Jie; Shao, Zhushuai; Pang, Ming; Luo, Jun E-mail: luojun@shu.edu.cn

    2014-01-15

    Near-field electrospinning (NFES) had better controllability than conventional electrospinning. However, due to the lack of guidance of theoretical model, precise deposition of micro/nano fibers could only accomplished by experience. To analyze the behavior of charged jet in NFES using mathematical model, the momentum balance equation was simplified and a new expression between jet cross-sectional radius and axial position was derived. Using this new expression and mass conservation equation, expressions for jet cross-sectional radius and velocity were derived in terms of axial position and initial jet acceleration in the form of exponential functions. Based on Slender-body theory and Giesekus model, a quadratic equation for initial jet acceleration was acquired. With the proposed model, it was able to accurately predict the diameter and velocity of polymer fibers in NFES, and mathematical analysis rather than experimental methods could be applied to study the effects of the process parameters in NFES. Moreover, the movement velocity of the collector stage can be regulated by mathematical model rather than experience. Therefore, the model proposed in this paper had important guiding significance to precise deposition of polymer fibers.

  20. Three-dimensional near-field MIMO array imaging using range migration techniques.

    PubMed

    Zhuge, Xiaodong; Yarovoy, Alexander G

    2012-06-01

    This paper presents a 3-D near-field imaging algorithm that is formulated for 2-D wideband multiple-input-multiple-output (MIMO) imaging array topology. The proposed MIMO range migration technique performs the image reconstruction procedure in the frequency-wavenumber domain. The algorithm is able to completely compensate the curvature of the wavefront in the near-field through a specifically defined interpolation process and provides extremely high computational efficiency by the application of the fast Fourier transform. The implementation aspects of the algorithm and the sampling criteria of a MIMO aperture are discussed. The image reconstruction performance and computational efficiency of the algorithm are demonstrated both with numerical simulations and measurements using 2-D MIMO arrays. Real-time 3-D near-field imaging can be achieved with a real-aperture array by applying the proposed MIMO range migration techniques. PMID:22345541

  1. Noise analysis for near field 3-D FM-CW radar imaging systems

    SciTech Connect

    Sheen, David M.

    2015-06-19

    Near field radar imaging systems are used for several applications including concealed weapon detection in airports and other high-security venues. Despite the near-field operation, phase noise and thermal noise can limit the performance in several ways including reduction in system sensitivity and reduction of image dynamic range. In this paper, the effects of thermal noise, phase noise, and processing gain are analyzed in the context of a near field 3-D FM-CW imaging radar as might be used for concealed weapon detection. In addition to traditional frequency domain analysis, a time-domain simulation is employed to graphically demonstrate the effect of these noise sources on a fast-chirping FM-CW system.

  2. Planar Near-Field Phase Retrieval Using GPUs for Accurate THz Far-Field Prediction

    NASA Astrophysics Data System (ADS)

    Junkin, Gary

    2013-04-01

    With a view to using Phase Retrieval to accurately predict Terahertz antenna far-field from near-field intensity measurements, this paper reports on three fundamental advances that achieve very low algorithmic error penalties. The first is a new Gaussian beam analysis that provides accurate initial complex aperture estimates including defocus and astigmatic phase errors, based only on first and second moment calculations. The second is a powerful noise tolerant near-field Phase Retrieval algorithm that combines Anderson's Plane-to-Plane (PTP) with Fienup's Hybrid-Input-Output (HIO) and Successive Over-Relaxation (SOR) to achieve increased accuracy at reduced scan separations. The third advance employs teraflop Graphical Processing Units (GPUs) to achieve practically real time near-field phase retrieval and to obtain the optimum aperture constraint without any a priori information.

  3. Far-field patterns of spaceborne antennas from plane-polar near-field measurements

    NASA Technical Reports Server (NTRS)

    Rahmat-Samii, Y.; Gatti, M. S.

    1985-01-01

    Certain unique features of a recently constructed plane-polar near-field measurement facility for determining the far-field patterns of large and fragile spaceborne antennas are described. In this facility, the horizontally positioned antenna rotates about its axis while the measuring probe is advanced incrementally in a fixed radial direction. The near-field measured data is then processed using a Jacobi-Bessel expansion to obtain the antenna far fields. A summary of the measurement and computational steps is given. Comparisons between the outdoor far-field measurements and the constructed far-field patterns from the near-field measured data are provided for different antenna sizes and frequencies. Application of the substitution method for the absolute gain measurement is discussed. In particular, results are shown for the 4.8-m mesh-deployable high-gain antenna of the Galileo spacecraft which has the mission of orbiting Jupiter in 1988.

  4. Rupture process of the 2010 Mw 7.8 Mentawai tsunami earthquake from joint inversion of near-field hr-GPS and teleseismic body wave recordings constrained by tsunami observations

    NASA Astrophysics Data System (ADS)

    Yue, Han; Lay, Thorne; Rivera, Luis; Bai, Yefei; Yamazaki, Yoshiki; Cheung, Kwok Fai; Hill, Emma M.; Sieh, Kerry; Kongko, Widjo; Muhari, Abdul

    2014-07-01

    The 25 October 2010 Mentawai tsunami earthquake (Mw 7.8) ruptured the shallow portion of the Sunda megathrust seaward of the Mentawai Islands, offshore of Sumatra, Indonesia, generating a strong tsunami that took 509 lives. The rupture zone was updip of those of the 12 September 2007 Mw 8.5 and 7.9 underthrusting earthquakes. High-rate (1 s sampling) GPS instruments of the Sumatra GPS Array network deployed on the Mentawai Islands and Sumatra mainland recorded time-varying and static ground displacements at epicentral distances from 49 to 322 km. Azimuthally distributed tsunami recordings from two deepwater sensors and two tide gauges that have local high-resolution bathymetric information provide additional constraints on the source process. Finite-fault rupture models, obtained by joint inversion of the high-rate (hr)-GPS time series and numerous teleseismic broadband P and S wave seismograms together with iterative forward modeling of the tsunami recordings, indicate rupture propagation ~50 km up dip and ~100 km northwest along strike from the hypocenter, with a rupture velocity of ~1.8 km/s. Subregions with large slip extend from 7 to 10 km depth ~80 km northwest from the hypocenter with a maximum slip of 8 m and from ~5 km depth to beneath thin horizontal sedimentary layers beyond the prism deformation front for ~100 km along strike, with a localized region having >15 m of slip. The seismic moment is 7.2 × 1020 N m. The rupture model indicates that local heterogeneities in the shallow megathrust can accumulate strain that allows some regions near the toe of accretionary prisms to fail in tsunami earthquakes.

  5. Laser wavelength effects in ultrafast near-field laser nanostructuring of Si

    SciTech Connect

    Zormpa, Vasileia; Mao, Xianglei; Russo, Richard E.

    2010-03-18

    We study the effect of laser wavelength (400 nm and 800 nm) on the near-field processing of crystalline silicon (Si) in the femtosecond (fs) pulse duration regime through sub-wavelength apertures. Distinct differences in the obtained nanostructures are found in each case both in terms of their physical sizes as well as their structure which can be tuned between craters and protrusions. A single or a few fs pulses can deliver enough energy on the substrate to induce sub-diffraction limited surface modification, which is among the smallest ever reported in sub-wavelength apertured Near-field Scanning Optical Microscope (NSOM) schemes.

  6. Towards better scanning near-field optical microscopy probes--progress and new developments.

    PubMed

    Heinzelmann, H; Freyland, J M; Eckert, R; Huser, T; Schürmann, G; Noell, W; Staufer, U; De Rooij, N F

    1999-01-01

    Several approaches are described with the aim of producing near-field optical probes with improved properties. Focused ion beam milling allows the fabrication of small apertures in a controlled fashion, resulting in probes with excellent polarization properties and increased transmission. Microfabrication processes are described that allow the production of apertures of 30-50 nm, facilitating the mass-fabrication of apertured tip structures that can be used in a combined force/near-field optical microscope. Finally, possible future developments are outlined. PMID:11388268

  7. Coupling Processes between Atmospheric Chemistry and Climate

    NASA Technical Reports Server (NTRS)

    Ko, M. K. W.; Weisenstein, Debra; Shia, Run-Lie; Sze, N. D.

    1998-01-01

    This is the third semi-annual report for NAS5-97039, covering January through June 1998. The overall objective of this project is to improve the understanding of coupling processes between atmospheric chemistry and climate. Model predictions of the future distributions of trace gases in the atmosphere constitute an important component of the input necessary for quantitative assessments of global change. We will concentrate on the changes in ozone and stratospheric sulfate aerosol, with emphasis on how ozone in the lower stratosphere would respond to natural or anthropogenic changes. The key modeling for this work are the AER 2-dimensional chemistry-transport model, the AER 2-dimensional stratospheric sulfate model, and the AER three-wave interactive model with full chemistry. We will continue developing our three-wave model so that we can help NASA determine the strengths and weaknesses of the next generation assessment models.

  8. Coupling Processes Between Atmospheric Chemistry and Climate

    NASA Technical Reports Server (NTRS)

    Ko, Malcolm K. W.; Weisenstein, Debra; Rodriguez, Jose; Danilin, Michael; Scott, Courtney; Shia, Run-Lie; Eluszkiewicz, Junusz; Sze, Nien-Dak

    1999-01-01

    This is the final report. The overall objective of this project is to improve the understanding of coupling processes among atmospheric chemistry, aerosol and climate, all important for quantitative assessments of global change. Among our priority are changes in ozone and stratospheric sulfate aerosol, with emphasis on how ozone in the lower stratosphere would respond to natural or anthropogenic changes. The work emphasizes two important aspects: (1) AER's continued participation in preparation of, and providing scientific input for, various scientific reports connected with assessment of stratospheric ozone and climate. These include participation in various model intercomparison exercises as well as preparation of national and international reports. and (2) Continued development of the AER three-wave interactive model to address how the transport circulation will change as ozone and the thermal properties of the atmosphere change, and assess how these new findings will affect our confidence in the ozone assessment results.

  9. Coupling Processes Between Atmospheric Chemistry and Climate

    NASA Technical Reports Server (NTRS)

    Ko, Malcolm K. W.; Weisenstein, Debra; Shia, Run-Lie; Sze, N. D.

    1998-01-01

    The overall objective of this project is to improve the understanding of coupling processes between atmospheric chemistry and climate. Model predictions of the future distributions of trace gases in the atmosphere constitute an important component of the input necessary for quantitative assessments of global change. We will concentrate on the changes in ozone and stratospheric sulfate aerosol, with emphasis on how ozone in the lower stratosphere would respond to natural or anthropogenic changes. The key modeling tools for this work are the AER 2-dimensional chemistry-transport model, the AER 2-dimensional stratospheric sulfate model, and the AER three-wave interactive model with full chemistry. We will continue developing our three-wave model so that we can help NASA determine the strength and weakness of the next generation assessment models.

  10. Coupling Processes Between Atmospheric Chemistry and Climate

    NASA Technical Reports Server (NTRS)

    Ko, M. K. W.; Weisenstein, Debra; Shia, Run-Lie; Sze, N. D.

    1998-01-01

    The overall objective of this project is to improve the understanding of coupling processes between atmospheric chemistry and climate. Model predictions of the future distributions of trace gases in the atmosphere constitute an important component of the input necessary for quantitative assessments of global change. We will concentrate on the changes in ozone and stratospheric sulfate aerosol, with emphasis on how ozone in the lower stratosphere would respond to natural or anthropogenic changes. The key modeling tools for this work are the AER two-dimensional chemistry-transport model, the AER two-dimensional stratospheric sulfate model, and the AER three-wave interactive model with full chemistry. We will continue developing our three-wave model so that we can help NASA determine the strength and weakness of the next generation assessment models.

  11. Near-field imaging and spectroscopy of hybridized plasmons (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Aeschlimann, Martin

    2015-09-01

    Understanding light-matter interactions such as the dynamic response of a metal to incident light is essential for advancing fundamental research and technological applications e.g. designing plasmonic devices such as nanoantenna directional emitters. The near-field response is determined on a length scale that is intrinsically smaller than the optical diffraction limit and so we use electrons to image the near-field distribution. We combine photoemission electron microscopy (PEEM) with a variable wavelength laser light source, an optical parametric oscillator (OPO), to perform near-field imaging and spectroscopy of whispering gallery resonator (WGR)1 arrays. These ultrahigh spatially and spectrally resolved measurements show characteristic spectral peaks and near-field mode distributions due to the excitation of different plasmon resonances. Controlling the interference between dipole and quadrupole modes allows us to direct the emission from the nanoantenna. Additionally we perform femtosecond 2-dimensional coherence spectroscopy2 on a microcavity system containing two well separated WGR nanoantennas. Hybridization of a propagating surface plasmon polariton and the localized surface plasmon in a cavity enables energy transfer between the two coupled nanoantennas. [1] E. J. R. Vessseur, F. J. García de Abajo and A. Polman Nano Letters 9 3147 (2009) [2] M. Aeschlimann et al, Science 333, 1723 (2011)

  12. Hybridized plasmon modes and near-field enhancement of metallic nanoparticle-dimer on a mirror

    PubMed Central

    Huang, Yu; Ma, Lingwei; Hou, Mengjing; Li, Jianghao; Xie, Zheng; Zhang, Zhengjun

    2016-01-01

    For the attractive plasmonic structure consisting of metal nanoparticles (NPs) on a mirror, the coexistence of near-field NP-NP and NP-mirror couplings is numerically studied at normal incidence. By mapping their 3D surface charge distributions directly, we have demonstrated two different kinds of mirror-induced bonding dipole plasmon modes and confirmed the bonding hybridizations of the mirror and the NP-dimer which may offer a much stronger near-field enhancement than that of the isolated NP dimers over a broad wavelength range. Further, it is revealed that the huge near-field enhancement of these two modes exhibit different dependence on the NP-NP and NP-mirror hot spots, while both of their near-field resonance wavelengths can be tuned to the blue exponentially by increasing the NP-NP gaps or the NP-mirror separation. Our results here benifit significantly the fundamental understanding and practical applications of metallic NPs on a mirror in plasmonics. PMID:27418039

  13. A near-field scanning microwave microscope based on a superconducting resonator for low power measurements.

    PubMed

    de Graaf, S E; Danilov, A V; Adamyan, A; Kubatkin, S E

    2013-02-01

    We report on the design and performance of a cryogenic (300 mK) near-field scanning microwave microscope. It uses a microwave resonator as the near-field sensor, operating at a frequency of 6 GHz and microwave probing amplitudes down to 100 μV, approaching low enough photon population (N ∼ 1000) of the resonator such that coherent quantum manipulation becomes feasible. The resonator is made out of a miniaturized distributed fractal superconducting circuit that is integrated with the probing tip, micromachined to be compact enough such that it can be mounted directly on a quartz tuning-fork, and used for parallel operation as an atomic force microscope (AFM). The resonator is magnetically coupled to a transmission line for readout, and to achieve enhanced sensitivity we employ a Pound-Drever-Hall measurement scheme to lock to the resonance frequency. We achieve a well localized near-field around the tip such that the microwave resolution is comparable to the AFM resolution, and a capacitive sensitivity down to 6.4 × 10(-20) F/Hz, limited by mechanical noise. We believe that the results presented here are a significant step towards probing quantum systems at the nanoscale using near-field scanning microwave microscopy. PMID:23464217

  14. Near-field thermal radiation between homogeneous dual uniaxial electromagnetic metamaterials

    NASA Astrophysics Data System (ADS)

    Chang, Jui-Yung; Basu, Soumyadipta; Yang, Yue; Wang, Liping

    2016-06-01

    Recently, near-field thermal radiation has attracted much attention in several fields since it can exceed the Planck blackbody limit through the coupling of evanescent waves. In this work, near-field radiative heat transfer between two semi-infinite dual uniaxial electromagnetic metamaterials with two different material property sets is theoretically analyzed. The near-field radiative heat transfer is calculated using fluctuational electrodynamics incorporated with anisotropic wave optics. The underlying mechanisms, namely, magnetic hyperbolic mode, magnetic surface polariton, electrical hyperbolic mode, and electrical surface polariton, between two homogeneous dual uniaxial electromagnetic metamaterials are investigated by examining the transmission coefficient and the spectral heat flux. The effect of vacuum gap distance is also studied, which shows that the enhancement at smaller vacuum gap is mainly due to hyperbolic mode and surface plasmon polariton modes. In addition, the results show that the contribution of s-polarized waves is significant and should not be excluded due to the strong magnetic response regardless of vacuum gap distances. The fundamental understanding and insights obtained here will facilitate the finding and application of novel materials for near-field thermal radiation.

  15. Far-Field Super-resolution Detection of Plasmonic Near-Fields.

    PubMed

    Boutelle, Robert Charles; Neuhauser, Daniel; Weiss, Shimon

    2016-08-23

    We demonstrate a far-field single molecule super-resolution method that maps plasmonic near-fields. The method is largely invariant to fluorescence quenching (arising from probe proximity to a metal), has reduced point-spread-function distortion compared to fluorescent dyes (arising from strong coupling to nanoscopic metallic features), and has a large dynamic range (of 2 orders of magnitude) allowing mapping of plasmonic field-enhancements regions. The method takes advantage of the sensitivity of quantum dot (QD) stochastic blinking to plasmonic near-fields. The modulation of the blinking characteristics thus provides an indirect measure of the local field strength. Since QD blinking can be monitored in the far-field, the method can measure localized plasmonic near-fields at high throughput using a simple far-field optical setup. Using this method, propagation lengths and penetration depths were mapped-out for silver nanowires of different diameters and for different dielectric environments, with a spatial accuracy of ∼15 nm. We initially use sparse sampling to ensure single molecule localization for accurate characterization of the plasmonic near-field with plans to increase density of emitters in further studies. The measured propagation lengths and penetration depths values agree well with Maxwell finite-difference time-domain calculations and with published literature values. This method offers advantages such as low cost, high throughput, and superresolved mapping of localized plasmonic fields at high sensitivity and fidelity. PMID:27501216

  16. Hybridized plasmon modes and near-field enhancement of metallic nanoparticle-dimer on a mirror.

    PubMed

    Huang, Yu; Ma, Lingwei; Hou, Mengjing; Li, Jianghao; Xie, Zheng; Zhang, Zhengjun

    2016-01-01

    For the attractive plasmonic structure consisting of metal nanoparticles (NPs) on a mirror, the coexistence of near-field NP-NP and NP-mirror couplings is numerically studied at normal incidence. By mapping their 3D surface charge distributions directly, we have demonstrated two different kinds of mirror-induced bonding dipole plasmon modes and confirmed the bonding hybridizations of the mirror and the NP-dimer which may offer a much stronger near-field enhancement than that of the isolated NP dimers over a broad wavelength range. Further, it is revealed that the huge near-field enhancement of these two modes exhibit different dependence on the NP-NP and NP-mirror hot spots, while both of their near-field resonance wavelengths can be tuned to the blue exponentially by increasing the NP-NP gaps or the NP-mirror separation. Our results here benifit significantly the fundamental understanding and practical applications of metallic NPs on a mirror in plasmonics. PMID:27418039

  17. A near-field scanning microwave microscope based on a superconducting resonator for low power measurements

    NASA Astrophysics Data System (ADS)

    de Graaf, S. E.; Danilov, A. V.; Adamyan, A.; Kubatkin, S. E.

    2013-02-01

    We report on the design and performance of a cryogenic (300 mK) near-field scanning microwave microscope. It uses a microwave resonator as the near-field sensor, operating at a frequency of 6 GHz and microwave probing amplitudes down to 100 {μ V}, approaching low enough photon population (N ˜ 1000) of the resonator such that coherent quantum manipulation becomes feasible. The resonator is made out of a miniaturized distributed fractal superconducting circuit that is integrated with the probing tip, micromachined to be compact enough such that it can be mounted directly on a quartz tuning-fork, and used for parallel operation as an atomic force microscope (AFM). The resonator is magnetically coupled to a transmission line for readout, and to achieve enhanced sensitivity we employ a Pound-Drever-Hall measurement scheme to lock to the resonance frequency. We achieve a well localized near-field around the tip such that the microwave resolution is comparable to the AFM resolution, and a capacitive sensitivity down to 6.4 × 10-20 F/sqrt{Hz}, limited by mechanical noise. We believe that the results presented here are a significant step towards probing quantum systems at the nanoscale using near-field scanning microwave microscopy.

  18. Infrared spectroscopic near-field mapping of single nanotransistors.

    PubMed

    Huber, A J; Wittborn, J; Hillenbrand, R

    2010-06-11

    We demonstrate the application of scattering-type scanning near-field optical microscopy (s-SNOM) for infrared (IR) spectroscopic material recognition in state-of-the-art semiconductor devices. In particular, we employ s-SNOM for imaging of industrial CMOS transistors with a resolution better than 20 nm, which allows for the first time IR spectroscopic recognition of amorphous SiO(2) and Si(3)N(4) components in a single transistor device. The experimentally recorded near-field spectral signature of amorphous SiO(2) shows excellent agreement with model calculations based on literature dielectric values, verifying that the characteristic near-field contrasts of SiO(2) stem from a phonon-polariton resonant near-field interaction between the probing tip and the SiO(2) nanostructures. Local material recognition by s-SNOM in combination with its capabilities of contact-free and non-invasive conductivity- and strain-mapping makes IR near-field microscopy a versatile metrology technique for nanoscale material characterization and semiconductor device analysis with application potential in research and development, failure analysis and reverse engineering. PMID:20463381

  19. Near-field fiber optic chemical sensors and biological applications

    NASA Astrophysics Data System (ADS)

    Tan, Weihong; Shi, Zhong-You; Thorsrud, Bjorn A.; Harris, C.; Kopelman, Raoul

    1994-03-01

    Near-field optics has been applied in the nanofabrication of subwavelength optical fiber chemical and biological sensors and their operation in chemical and biological analysis. A thousandfold miniaturization of immobilized optical fiber sensors has been achieved by a near- field photo-nanofabrication technique, which is based on nanofabricated optical fiber tips and near-field photopolymerization. This technique has been further developed by multistep near- field nanofabrication and multidye probe fabrication. Multistep nanofabrication can further miniaturize optical fiber sensors, while multidye fabrication results in multifunctional optic and excitonic probes with extremely small size. These probes emit multiwavelength photons or produce excitons of different energy levels, and may have multiple chemical or biological sensitivities. The nondestructive submicrometer sensor has demonstrated its ability to carry out static and dynamic determinations of pH in intact rat conceptuses of varying gestational ages. The ability of the sensors to measure pH changes, in real time, in the intact rat conceptus, demonstrates their potential applications for dynamic analysis in multicellular organisms and single cells. The near-field interaction of photons with matter is discussed.

  20. THz near-field imaging of biological tissues employing synchrotronradiation

    SciTech Connect

    Schade, Ulrich; Holldack, Karsten; Martin, Michael C.; Fried,Daniel

    2004-12-23

    Terahertz scanning near-field infrared microscopy (SNIM) below 1 THz is demonstrated. The near-field technique benefits from the broadband and highly brilliant coherent synchrotron radiation (CSR) from an electron storage ring and from a detection method based on locking onto the intrinsic time structure of the synchrotron radiation. The scanning microscope utilizes conical wave guides as near-field probes with apertures smaller than the wavelength. Different cone approaches have been investigated to obtain maximum transmittance. Together with a Martin-Puplett spectrometer the set-up enables spectroscopic mapping of the transmittance of samples well below the diffraction limit. Spatial resolution down to about lambda/40 at 2 wavenumbers (0.06 THz) is derived from the transmittance spectra of the near-field probes. The potential of the technique is exemplified by imaging biological samples. Strongly absorbing living leaves have been imaged in transmittance with a spatial resolution of 130 mu-m at about 12 wave numbers (0.36 THz). The THz near-field images reveal distinct structural differences of leaves from different plants investigated. The technique presented also allows spectral imaging of bulky organic tissues. Human teeth samples of various thicknesses have been imaged between 2 and 20 wavenumbers (between 0.06and 0.6 THz). Regions of enamel and dentin within tooth samples are spatially and spectrally resolved, and buried caries lesions are imaged through both the outer enamel and into the underlying dentin.

  1. Near-field radiative thermal transport: From theory to experiment

    SciTech Connect

    Song, Bai Fiorino, Anthony; Meyhofer, Edgar; Reddy, Pramod

    2015-05-15

    Radiative thermal transport via the fluctuating electromagnetic near-field has recently attracted increasing attention due to its fundamental importance and its impact on a range of applications from data storage to thermal management and energy conversion. After a brief historical account of radiative thermal transport, we summarize the basics of fluctuational electrodynamics, a theoretical framework for the study of radiative heat transfer in terms of thermally excited propagating and evanescent electromagnetic waves. Various approaches to modeling near-field thermal transport are briefly discussed, together with key results and proposals for manipulation and utilization of radiative heat flow. Subsequently, we review the experimental advances in the characterization of both near-field heat flow and energy density. We conclude with remarks on the opportunities and challenges for future explorations of radiative heat transfer at the nanoscale.

  2. Diagnose human tumors by THz near-field imaging

    NASA Astrophysics Data System (ADS)

    Chen, Hua; Wang, Xiaozhou; Zhao, Tian; Yang, Jinwen

    2014-09-01

    Based on a THz pipe-based near-field imaging system, we demonstrated the capability of THz imaging to diagnose human breast and liver cancers. Through THz near-field mapping of the absorption constants of cancer tissues, the acquired images can not only clearly distinguish cancer from normal tissues fast, automatically, and correctly without pathological H&E staining, but also identify the distribution region of cancer, which matches well with the identification with pathological examination. Due to its capability to perform quantitative analysis, our study indicates the potential of the THz pipe-based near-field imaging for future automation on human tumor pathological examinations and for quick definition of the tumor margins during the surgical procedure such as breast-conserving surgery. With the help of THz imaging, we can expect to economize the use of hospital and human resources.

  3. Near-field acoustical holography of military jet aircraft noise

    NASA Astrophysics Data System (ADS)

    Wall, Alan T.; Gee, Kent L.; Neilsen, Tracianne; Krueger, David W.; Sommerfeldt, Scott D.; James, Michael M.

    2010-10-01

    Noise radiated from high-performance military jet aircraft poses a hearing-loss risk to personnel. Accurate characterization of jet noise can assist in noise prediction and noise reduction techniques. In this work, sound pressure measurements were made in the near field of an F-22 Raptor. With more than 6000 measurement points, this is the most extensive near-field measurement of a high-performance jet to date. A technique called near-field acoustical holography has been used to propagate the complex pressure from a two- dimensional plane to a three-dimensional region in the jet vicinity. Results will be shown and what they reveal about jet noise characteristics will be discussed.

  4. Near-field energy extraction with hyperbolic metamaterials.

    PubMed

    Shi, Jiawei; Liu, Baoan; Li, Pengfei; Ng, Li Yen; Shen, Sheng

    2015-02-11

    Although blackbody radiation described by Planck's law is commonly regarded as the maximum of thermal radiation, thermal energy transfer in the near-field can exceed the blackbody limit due to the contribution from evanescent waves. Here, we demonstrate experimentally a broadband thermal energy extraction device based on hyperbolic metamaterials that can significantly enhance near-field thermal energy transfer. The thermal extractor made from hyperbolic metamaterials does not absorb or emit any radiation but serves as a transparent pipe guiding the radiative energy from the emitter. At the same gap between an emitter and an absorber, we observe that near-field thermal energy transfer with thermal extraction can be enhanced by around 1 order of magnitude, compared to the case without thermal extraction. The novel thermal extraction scheme has important practical implications in a variety of technologies, e.g., thermophotovoltaic energy conversion, radiative cooling, thermal infrared imaging, and heat assisted magnetic recording. PMID:25622221

  5. Processes of Change in Self-Directed Couple Relationship Education

    ERIC Educational Resources Information Center

    Wilson, Keithia L.; Halford, W. Kim

    2008-01-01

    The current study examined the learning processes involved in professionally supported self-directed couple relationship education (CRE). Fifty-nine couples completed Couple CARE, a systematic, self-directed CRE program designed in flexible delivery mode to be completed at home. Couples watched a DVD introducing key relationship ideas and skills…

  6. A sensitive near-field microscope for thermal radiation.

    PubMed

    Kajihara, Yusuke; Kosaka, Keishi; Komiyama, Susumu

    2010-03-01

    A scattering-type scanning near-field optical microscope in long-wavelength infrared (LWIR) region is developed by using an extremely sensitive detector, called the charge-sensitive infrared phototransistor. A tungsten probe attached to a quartz tuning fork is controlled in shear-force mode. Evanescent wave at a sample surface is periodically scattered by slowly (2 Hz) modulating the probe in the direction normal to the sample surface. Near-field microscopy of thermal LWIR radiation from room-temperature Au/GaAs gratings is demonstrated without using any external illumination or excitation. Achieved spatial resolution is better than 300 nm. PMID:20370184

  7. Photonic near-field imaging in multiphoton photoemission electron microscopy

    NASA Astrophysics Data System (ADS)

    Fitzgerald, J. P. S.; Word, R. C.; Saliba, S. D.; Könenkamp, R.

    2013-05-01

    We report the observation of optical near fields in a photonic waveguide of conductive indium tin oxide (ITO) using multiphoton photoemission electron microscopy (PEEM). Nonlinear two-photon photoelectron emission is enhanced at field maxima created by interference between incident 410-nm and coherently excited guided photonic waves, providing strong phase contrast. Guided modes are observed under both transverse magnetic field (TM) and transverse electric field (TE) polarized illuminations and are consistent with classical electromagnetic theory. Implications on the role of multiphoton PEEM in optical near-field imaging are discussed.

  8. Towards phonon photonics: scattering-type near-field optical microscopy reveals phonon-enhanced near-field interaction.

    PubMed

    Hillenbrand, Rainer

    2004-08-01

    Diffraction limits the spatial resolution in classical microscopy or the dimensions of optical circuits to about half the illumination wavelength. Scanning near-field microscopy can overcome this limitation by exploiting the evanescent near fields existing close to any illuminated object. We use a scattering-type near-field optical microscope (s-SNOM) that uses the illuminated metal tip of an atomic force microscope (AFM) to act as scattering near-field probe. The presented images are direct evidence that the s-SNOM enables optical imaging at a spatial resolution on a 10nm scale, independent of the wavelength used (lambda=633 nm and 10 microm). Operating the microscope at specific mid-infrared frequencies we found a tip-induced phonon-polariton resonance on flat polar crystals such as SiC and Si3N4. Being a spectral fingerprint of any polar material such phonon-enhanced near-field interaction has enormous applicability in nondestructive, material-specific infrared microscopy at nanoscale resolution. The potential of s-SNOM to study eigenfields of surface polaritons in nanostructures opens the door to the development of phonon photonics-a proposed infrared nanotechnology that uses localized or propagating surface phonon polaritons for probing, manipulating and guiding infrared light in nanoscale devices, analogous to plasmon photonics. PMID:15231334

  9. Ultrafast nanoelectronics: steering electrons in infrared near-fields (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Herink, Georg; Ropers, Claus

    2015-09-01

    Plasmonic nanostructures can break the diffraction limit and confine optical fields on the nanoscale. The coupling of intense femtosecond transients to the apex of metallic nanotips enables ultrafast electron point sources which find applications in ultrafast electron microscopy and time-resolved diffraction instruments. In this contribution, we demonstrate the impact of near-field localization onto strong-field photoemission and present the control of electron trajectories via the momentary electric near-field. The photoemission dynamics at single gold and tungsten nanotips are experimentally studied over a broad range of excitation frequencies, spanning from 1 - 400 Terahertz (THz). The transition from oscillatory electron acceleration to a field-driven interaction is presented as a result of intense, long-wavelength and localized excitation. The high field enhancement at lower frequencies is demonstrated to induce localized field emission from a nanotip with moderate incident fields as provided by table-top THz sources. Such THz-induced cold field emission can be used, e.g., for the temporal tracking of optically excited hot-electron dynamics in nanostructures. Moreover, the field-driven electron acceleration in the enhanced THz near-field is employed in a pump-probe scheme to temporally map the local THz-response of the nanostructure by projecting the momentary apex near-field onto the kinetic energy of femtosecond electron pulses. Besides the electrical characterization of nanostructures at THz-frequencies, the temporally and spatially confined interaction of free electrons with ultrashort near-fields is expected to enable a novel class of ultrafast vacuum micro- and nanoelectronic devices, and first applications are presented in this talk.

  10. Coupling Processes Between Atmospheric Chemistry and Climate

    NASA Technical Reports Server (NTRS)

    Ko, M. K. W.; Weisenstein, Debra; Shia, Run-Li; Sze, N. D.

    1997-01-01

    This is the first semi-annual report for NAS5-97039 summarizing work performed for January 1997 through June 1997. Work in this project is related to NAS1-20666, also funded by NASA ACMAP. The work funded in this project also benefits from work at AER associated with the AER three-dimensional isentropic transport model funded by NASA AEAP and the AER two-dimensional climate-chemistry model (co-funded by Department of Energy). The overall objective of this project is to improve the understanding of coupling processes between atmospheric chemistry and climate. Model predictions of the future distributions of trace gases in the atmosphere constitute an important component of the input necessary for quantitative assessments of global change. We will concentrate on the changes in ozone and stratospheric sulfate aerosol, with emphasis on how ozone in the lower stratosphere would respond to natural or anthropogenic changes. The key modeling tools for this work are the AER two-dimensional chemistry-transport model, the AER two-dimensional stratospheric sulfate model, and the AER three-wave interactive model with full chemistry.

  11. Coupling Processes between Atmospheric Chemistry and Climate

    NASA Technical Reports Server (NTRS)

    Ko, Malcolm K. W.; Weisenstein, Debra K.; Shia, Run-Lie; Scott, Courtney J.; Sze, Nien Dak

    1998-01-01

    This is the fourth semi-annual report for NAS5-97039, covering the time period July through December 1998. The overall objective of this project is to improve the understanding of coupling processes between atmospheric chemistry and climate. Model predictions of the future distributions of trace gases in the atmosphere constitute an important component of the input necessary for quantitative assessments of global change. We will concentrate on the changes in ozone and stratospheric sulfate aerosol, with emphasis on how ozone in the lower stratosphere would respond to natural or anthropogenic changes. The key modeling tools for this work are the Atmospheric and Environmental Research (AER) two-dimensional chemistry-transport model, the AER two-dimensional stratospheric sulfate model, and the AER three-wave interactive model with full chemistry. For this six month period, we report on a modeling study of new rate constant which modify the NOx/NOy ratio in the lower stratosphere; sensitivity to changes in stratospheric water vapor in the future atmosphere; a study of N2O and CH4 observations which has allowed us to adjust diffusion in the 2-D CTM in order to obtain appropriate polar vortex isolation; a study of SF6 and age of air with comparisons of models and measurements; and a report on the Models and Measurements II effort.

  12. Coupling Processes Between Atmospheric Chemistry and Climate

    NASA Technical Reports Server (NTRS)

    Ko, Malcolm; Weisenstein, Debra; Rodriquez, Jose; Danilin, Michael; Scott, Courtney; Shia, Run-Lie; Eluszkiewicz, Janusz; Sze, Nien-Dak; Stewart, Richard W. (Technical Monitor)

    1999-01-01

    This is the final report for NAS5-97039 for work performed between December 1996 and November 1999. The overall objective of this project is to improve the understanding of coupling processes among atmospheric chemistry, aerosol and climate, all important for quantitative assessments of global change. Among our priority are changes in ozone and stratospheric sulfate aerosol, with emphasis on how ozone in the lower stratosphere would respond to natural or anthropogenic changes. The work emphasizes two important aspects: (1) AER's continued participation in preparation of, and providing scientific input for, various scientific reports connected with assessment of stratospheric ozone and climate. These include participation in various model intercomparison exercises as well as preparation of national and international reports. (2) Continued development of the AER three-wave interactive model to address how the transport circulation will change as ozone and the thermal properties of the atmosphere change, and assess how these new findings will affect our confidence in the ozone assessment results.

  13. Nano-Scale Fabrication Using Optical-Near-Field

    NASA Astrophysics Data System (ADS)

    Yatsui, Takashi; Ohtsu, Motoichi

    This paper reviews the specific nature of nanophotonics, i.e., a novel optical nano-technology, utilizing dressed photon excited in the nano-material. As examples of nanophotnic fabrication, optical near-field etching and increased spatial homogeneity of contents in compound semiconductors is demonstrated with a self-organized manner.

  14. Near-field analysis of a compressive supersonic ramp

    NASA Astrophysics Data System (ADS)

    Emanuel, George

    1982-07-01

    Steady, two-dimensional, inviscid, supersonic flow is analyzed for a compressive turn where the wall is contoured to provide a centered compression fan. The focal point of the compression is the origin of the usual (primary) oblique shock wave, a slipstream, and a secondary pressure disturbance. This disturbance can be an expansion, a weak solution shock, or a strong solution shock. In the vicinity of the focal point (the near field) there are seven possibilities, one of which is no real solution. For small wall turn angles, there is a unique near-field solution where the primary shock is the weak solution. In this case the secondary disturbance, whose strength is quite small, is either an expansion or a weak solution oblique shock wave. For larger turn angles, two near-field solutions are possible, and for still larger angles, none. At relatively large wall turn angles, where the usual oblique shock equations still provide an attached solution, the near-field equations do not have a solution when the Mach number is sufficiently large.

  15. Near-Field Spectroscopy with Nanoparticles Deposited by AFM

    NASA Technical Reports Server (NTRS)

    Anderson, Mark S.

    2008-01-01

    An alternative approach to apertureless near-field optical spectroscopy involving an atomic-force microscope (AFM) entails less complexity of equipment than does a prior approach. The alternative approach has been demonstrated to be applicable to apertureless near-field optical spectroscopy of the type using an AFM and surface enhanced Raman scattering (SERS), and is expected to be equally applicable in cases in which infrared or fluorescence spectroscopy is used. Apertureless near-field optical spectroscopy is a means of performing spatially resolved analyses of chemical compositions of surface regions of nanostructured materials. In apertureless near-field spectroscopy, it is common practice to utilize nanostructured probe tips or nanoparticles (usually of gold) having shapes and dimensions chosen to exploit plasmon resonances so as to increase spectroscopic-signal strengths. To implement the particular prior approach to which the present approach is an alternative, it is necessary to integrate a Raman spectrometer with an AFM and to utilize a special SERS-active probe tip. The resulting instrumentation system is complex, and the tasks of designing and constructing the system and using the system to acquire spectro-chemical information from nanometer-scale regions on a surface are correspondingly demanding.

  16. Nanostructuring thin polymer films with optical near fields.

    PubMed

    Martín-Fabiani, Ignacio; Siegel, Jan; Riedel, Stephen; Boneberg, Johannes; Ezquerra, Tiberio A; Nogales, Aurora

    2013-11-13

    In the present work, we report on the application of optical near fields to nanostructuring of poly(trimethylene terephthalate) (PTT) thin films. By exposure to a single ultraviolet nanosecond laser pulse, the spatial intensity modulation of the near-field distribution created by a silica microsphere is imprinted into the films. Setting different angles of incidence of the laser, elliptical or circular periodic ring patterns can be produced with periods as small as half the laser wavelength used. These highly complex patterns show optical and topographical contrast and can be characterized by optical microscopy (OM) and atomic force microscopy (AFM). We demonstrate the key role of the laser wavelength and coherence length in achieving smooth, extended patterns in PTT by using excimer laser (193 nm) and Nd:YAG laser (266 nm) pulses. Reference experiments performed in Ge2Sb2Te5 (GST) demonstrate that nanopatterning in PTT is triggered by ablation as opposed to GST, in which nanopatterning originates from laser-induced phase change, accompanied by a small topographical contrast. The experiments presented in this work demonstrate the suitability of optical near fields for structuring polymer films, opening up new possibilities for nanopatterning and paving the way for potential applications where optical near fields and polymer nanostructures are involved. PMID:24127989

  17. Near-Field Noise Computation for a Supersonic Circular Jet

    NASA Technical Reports Server (NTRS)

    Loh, Ching Y.; Hultgren, Lennart S.

    2005-01-01

    A fully expanded, high-Reynolds-number, supersonic circular jet of Mach number 1.4 is simulated, using a 3-D finite-volume Navier-Stokes solver, with emphasis on the near field noise. The numerical results are generally in good agreement with existing experimental findings.

  18. Near-Field Noise Computation for a Subsonic Coannular Jet

    NASA Technical Reports Server (NTRS)

    Loh, Ching Y.; Hultgren, Lennart S.; Jorgenson, Philip C. E.

    2008-01-01

    A high-Reynolds-number, subsonic coannular jet is simulated, using a three-dimensional finite-volume LES method, with emphasis on the near field noise. The nozzle geometry used is the NASA Glenn 3BB baseline model. The numerical results are generally in good agreement with existing experimental findings.

  19. Approximate Near-Field Blast Theory: A Generalized Approach

    SciTech Connect

    Hutchens, G.J.

    1999-10-25

    A method for analyzing strong shock waves in arbitrary one-dimensional geometry is presented. An approximation to classical Taylor-Sedov theory is extended to the near-field case where source mass is not negligible, accounting for differences in the chemical properties of the source mass and ambient medium. Results from example calculations are compared with previously published analytical formulae.

  20. Photon-induced near-field electron microscopy.

    PubMed

    Barwick, Brett; Flannigan, David J; Zewail, Ahmed H

    2009-12-17

    In materials science and biology, optical near-field microscopies enable spatial resolutions beyond the diffraction limit, but they cannot provide the atomic-scale imaging capabilities of electron microscopy. Given the nature of interactions between electrons and photons, and considering their connections through nanostructures, it should be possible to achieve imaging of evanescent electromagnetic fields with electron pulses when such fields are resolved in both space (nanometre and below) and time (femtosecond). Here we report the development of photon-induced near-field electron microscopy (PINEM), and the associated phenomena. We show that the precise spatiotemporal overlap of femtosecond single-electron packets with intense optical pulses at a nanostructure (individual carbon nanotube or silver nanowire in this instance) results in the direct absorption of integer multiples of photon quanta (nhomega) by the relativistic electrons accelerated to 200 keV. By energy-filtering only those electrons resulting from this absorption, it is possible to image directly in space the near-field electric field distribution, obtain the temporal behaviour of the field on the femtosecond timescale, and map its spatial polarization dependence. We believe that the observation of the photon-induced near-field effect in ultrafast electron microscopy demonstrates the potential for many applications, including those of direct space-time imaging of localized fields at interfaces and visualization of phenomena related to photonics, plasmonics and nanostructures. PMID:20016598

  1. Radiative heat transfer in the extreme near field.

    PubMed

    Kim, Kyeongtae; Song, Bai; Fernández-Hurtado, Víctor; Lee, Woochul; Jeong, Wonho; Cui, Longji; Thompson, Dakotah; Feist, Johannes; Reid, M T Homer; García-Vidal, Francisco J; Cuevas, Juan Carlos; Meyhofer, Edgar; Reddy, Pramod

    2015-12-17

    Radiative transfer of energy at the nanometre length scale is of great importance to a variety of technologies including heat-assisted magnetic recording, near-field thermophotovoltaics and lithography. Although experimental advances have enabled elucidation of near-field radiative heat transfer in gaps as small as 20-30 nanometres (refs 4-6), quantitative analysis in the extreme near field (less than 10 nanometres) has been greatly limited by experimental challenges. Moreover, the results of pioneering measurements differed from theoretical predictions by orders of magnitude. Here we use custom-fabricated scanning probes with embedded thermocouples, in conjunction with new microdevices capable of periodic temperature modulation, to measure radiative heat transfer down to gaps as small as two nanometres. For our experiments we deposited suitably chosen metal or dielectric layers on the scanning probes and microdevices, enabling direct study of extreme near-field radiation between silica-silica, silicon nitride-silicon nitride and gold-gold surfaces to reveal marked, gap-size-dependent enhancements of radiative heat transfer. Furthermore, our state-of-the-art calculations of radiative heat transfer, performed within the theoretical framework of fluctuational electrodynamics, are in excellent agreement with our experimental results, providing unambiguous evidence that confirms the validity of this theory for modelling radiative heat transfer in gaps as small as a few nanometres. This work lays the foundations required for the rational design of novel technologies that leverage nanoscale radiative heat transfer. PMID:26641312

  2. Measurement of the permittivity and loss of high-loss materials using a Near-Field Scanning Microwave Microscope.

    PubMed

    Gregory, A P; Blackburn, J F; Lees, K; Clarke, R N; Hodgetts, T E; Hanham, S M; Klein, N

    2016-02-01

    In this paper improvements to a Near-Field Scanning Microwave Microscope (NSMM) are presented that allow the loss of high loss dielectric materials to be measured accurately at microwave frequencies. This is demonstrated by measuring polar liquids (loss tangent tanδ≈1) for which traceable data is available. The instrument described uses a wire probe that is electromagnetically coupled to a resonant cavity. An optical beam deflection system is incorporated within the instrument to allow contact mode between samples and the probe tip to be obtained. Liquids are contained in a measurement cell with a window of ultrathin glass. The calibration process for the microscope, which is based on image-charge electrostatic models, has been adapted to use the Laplacian 'complex frequency'. Measurements of the loss tangent of polar liquids that are consistent with reference data were obtained following calibration against single-crystal specimens that have very low loss. PMID:26686660

  3. Generation of single-crystalline domain in nano-scale silicon pillars by near-field short pulsed laser

    NASA Astrophysics Data System (ADS)

    In, Jung Bin; Xiang, Bin; Hwang, David J.; Ryu, Sang-Gil; Kim, Eunpa; Yoo, Jae-Hyuck; Dubon, Oscar; Minor, Andrew M.; Grigoropoulos, Costas P.

    2014-01-01

    We observe laser-induced grain morphology change in silicon nanopillars under a transmission electron microscopy (TEM) environment. We couple the TEM with a near-field scanning optical microscopy pulsed laser processing system. This novel combination enables immediate scrutiny on the grain morphologies that the pulsed laser irradiation produces. We find unusual transformation of the tip of the amorphous or polycrystalline silicon pillar into a single crystalline domain via melt-mediated crystallization. On the basis of the three-dimensional finite difference simulation result and the dark field TEM data, we propose that the creation of the distinct single crystalline tip originates from the dominant grain growth initiated at the apex of the non-planar liquid-solid interface. Our microscopic observation provides a fundamental basis for laser-induced conversion of amorphous nanostructures into coarse-grained crystals.

  4. Surface-polariton propagation for scanning near-field optical microscopy application.

    PubMed

    Keilmann, F

    1999-01-01

    Surface plasmon-, phonon- and exciton-polaritons exist on specific materials in specific spectral regions. We assess the properties of such travelling surface-bound electromagnetic waves relevant for scanning near-field optical microscopy applications, i.e. the tightness of surface binding, the attenuation, the phase velocity and the coupling with free-space electromagnetic waves. These quantities can be directly determined by photographic imaging of surface plasmon- and surface phonon-polaritons, in both the visible and mid-infared regions. Focusing of mid-infrared surface plasmons is demonstrated. Surface waveguides to transport and focus photons to the tip of a scanning near-field probe are outlined. PMID:11388308

  5. Sub-10 nm near-field localization by plasmonic metal nanoaperture arrays with ultrashort light pulses

    PubMed Central

    Lee, Hongki; Kim, Chulhong; Kim, Donghyun

    2015-01-01

    Near-field localization by ultrashort femtosecond light pulses has been investigated using simple geometrical nanoapertures. The apertures employ circular, rhombic, and triangular shapes to localize the distribution of surface plasmon. To understand the geometrical effect on the localization, aperture length and period of the nanoapertures were varied. Aperture length was shown to affect the performance more than aperture period due mainly to intra-aperture coupling of near-fields. Triangular apertures provided the strongest spatial localization below 10 nm in size as well as the highest enhancement of field intensity by more than 7000 times compared to the incident light pulse. Use of ultrashort pulses was found to allow much stronger light localization than with continuous-wave light. The results can be used for super-localization sensing and imaging applications where spatially localized fields can break through the limits in achieving improved sensitivity and resolution. PMID:26628326

  6. Sub-10 nm near-field localization by plasmonic metal nanoaperture arrays with ultrashort light pulses.

    PubMed

    Lee, Hongki; Kim, Chulhong; Kim, Donghyun

    2015-01-01

    Near-field localization by ultrashort femtosecond light pulses has been investigated using simple geometrical nanoapertures. The apertures employ circular, rhombic, and triangular shapes to localize the distribution of surface plasmon. To understand the geometrical effect on the localization, aperture length and period of the nanoapertures were varied. Aperture length was shown to affect the performance more than aperture period due mainly to intra-aperture coupling of near-fields. Triangular apertures provided the strongest spatial localization below 10 nm in size as well as the highest enhancement of field intensity by more than 7000 times compared to the incident light pulse. Use of ultrashort pulses was found to allow much stronger light localization than with continuous-wave light. The results can be used for super-localization sensing and imaging applications where spatially localized fields can break through the limits in achieving improved sensitivity and resolution. PMID:26628326

  7. Electrically tunable near-field radiative heat transfer via ferroelectric materials

    SciTech Connect

    Huang, Yi; Boriskina, Svetlana V.; Chen, Gang

    2014-12-15

    We explore ways to actively control near-field radiative heat transfer between two surfaces that relies on electrical tuning of phonon modes of ferroelectric materials. Ferroelectrics are widely used for tunable electrical devices, such as capacitors and memory devices; however, their tunable properties have not yet been examined for heat transfer applications. We show via simulations that radiative heat transfer between two ferroelectric materials can be enhanced by over two orders of magnitude over the blackbody limit in the near field, and can be tuned as much as 16.5% by modulating the coupling between surface phonon polariton modes at the two surfaces via varying external electric fields. We then discuss how to maximize the modulation contrast for tunable thermal devices using the studied mechanism.

  8. Nonlinear nanoprobes for characterizing ultrafast optical near field

    NASA Astrophysics Data System (ADS)

    Li, Haifeng

    With the rapid development of ultrafast optics and nanophotonics, it is crucial to measure the spatiotemporal evolution of an ultrafast optical near field in nanometer spatial and femtosecond temporal resolution with minimal perturbation. Although near-field scanning optical microscopy (NSOM) can achieve nanoscale spatial resolution and various ultrashort pulse diagnostic tools can characterize femtosecond laser pulses, yet such capability to noninvasively characterize the nanoscale characteristics of femtosecond pulses in all three spatial dimensions remains elusive. In this dissertation, we developed different types of nonlinear optical probes to characterize ultrashort optical pulses. The nonlinear optical probe is composed of three parts, a silica fiber taper, a single nanowire bonded to the end of the fiber and nonlinear nanoparticles attached on the tip of the nanowire. The optical fiber taper can be readily mounted on a mechanical stage and served as a macroscopic interface for handling and positioning control. The single nanowire bridges the dimension gap between the nanocrystals and the fiber taper, and is critical for achieving large aspect ratio and hence minimizing optical scattering and perturbation. The nonlinear nanoparticles give rise to its capability to characterize ultrashort optical pulses. The unique fusion of nanoscale and nonlinear features in developed nonlinear optical probes provides the ability of probing ultrafast optical field in complex 3D microand nano- structures. The demonstration of such ability is crucial for understanding the interaction of ultrafast optical fields and nanoscale systems. The fabrication processes of the nonlinear optical probes are illustrated in detail and the optical properties of the probes are investigated. Two different types of nonlinear optical probes, two-photon fluorescent nanoprobes and Second HARmonic nanoProbes (SHARP), are fabricated. Interferometric autocorrelation measurements near the focal point

  9. Spectrally Enhancing Near-Field Radiative Transfer between Metallic Gratings by Exciting Magnetic Polaritons in Nanometric Vacuum Gaps

    NASA Astrophysics Data System (ADS)

    Yang, Yue; Wang, Liping

    2016-07-01

    In the present Letter, we theoretically demonstrate that near-field radiative transport between one-dimensional periodic grating microstructures separated by nanometer vacuum gaps can be spectrally enhanced by exciting magnetic polaritons. Fluctuational electrodynamics that incorporates scattering matrix theory with rigorous coupled-wave analysis is employed to exactly calculate the near-field radiative flux between two metallic gratings. In addition to the well-known coupled surface plasmon polaritons, the radiative flux can be also spectrally enhanced due to the magnetic polariton, which is excited in the gap between the grating ridges. The mechanism of magnetic polaritons in the near-field radiative transport are elucidated in detail, while the unusual enhancement cannot be predicted by either Derjaguin's or the effective medium approximations. The effects of the vacuum gap distance and grating geometry parameters between the two gratings are investigated. The findings will open a new way to spectrally control near-field radiative transfer by magnetic polaritons with micro- or nanostructured metamaterials, which holds great potential for improving the performance of energy systems like near-field thermophotovoltaics.

  10. Spectrally Enhancing Near-Field Radiative Transfer between Metallic Gratings by Exciting Magnetic Polaritons in Nanometric Vacuum Gaps.

    PubMed

    Yang, Yue; Wang, Liping

    2016-07-22

    In the present Letter, we theoretically demonstrate that near-field radiative transport between one-dimensional periodic grating microstructures separated by nanometer vacuum gaps can be spectrally enhanced by exciting magnetic polaritons. Fluctuational electrodynamics that incorporates scattering matrix theory with rigorous coupled-wave analysis is employed to exactly calculate the near-field radiative flux between two metallic gratings. In addition to the well-known coupled surface plasmon polaritons, the radiative flux can be also spectrally enhanced due to the magnetic polariton, which is excited in the gap between the grating ridges. The mechanism of magnetic polaritons in the near-field radiative transport are elucidated in detail, while the unusual enhancement cannot be predicted by either Derjaguin's or the effective medium approximations. The effects of the vacuum gap distance and grating geometry parameters between the two gratings are investigated. The findings will open a new way to spectrally control near-field radiative transfer by magnetic polaritons with micro- or nanostructured metamaterials, which holds great potential for improving the performance of energy systems like near-field thermophotovoltaics. PMID:27494474

  11. The thermal near-field: Coherence, spectroscopy, heat-transfer, and optical forces

    NASA Astrophysics Data System (ADS)

    Jones, Andrew C.; O'Callahan, Brian T.; Yang, Honghua U.; Raschke, Markus B.

    2013-12-01

    One of the most universal physical processes shared by all matter at finite temperature is the emission of thermal radiation. The experimental characterization and theoretical description of far-field black-body radiation was a cornerstone in the development of modern physics with the groundbreaking contributions from Gustav Kirchhoff and Max Planck. With its origin in thermally driven fluctuations of the charge carriers, thermal radiation reflects the resonant and non-resonant dielectric properties of media, which is the basis for far-field thermal emission spectroscopy. However, associated with the underlying fluctuating optical source polarization are fundamentally distinct spectral, spatial, resonant, and coherence properties of the evanescent thermal near-field. These properties have been recently predicted theoretically and characterized experimentally for systems with thermally excited molecular, surface plasmon polariton (SPP), and surface phonon polariton (SPhP) resonances. We review, starting with the early historical developments, the emergence of theoretical models, and the description of the thermal near-field based on the fluctuation-dissipation theory and in terms of the electromagnetic local density of states (EM-LDOS). We discuss the optical and spectroscopic characterization of distance dependence, magnitude, spectral distribution, and coherence of evanescent thermal fields. Scattering scanning near-field microscopy proved instrumental as an enabling technique for the investigations of several of these fundamental thermal near-field properties. We then discuss the role of thermal fields in nano-scale heat transfer and optical forces, and the correlation to the van der Waals, Casimir, and Casimir-Polder forces. We conclude with an outlook on the possibility of intrinsic and extrinsic resonant manipulation of optical forces, control of nano-scale radiative heat transfer with optical antennas and metamaterials, and the use of thermal infrared near-field

  12. Thermal excitation of plasmons for near-field thermophotovoltaics

    SciTech Connect

    Guo, Yu; Molesky, Sean; Hu, Huan; Cortes, Cristian L.; Jacob, Zubin

    2014-08-18

    The traditional approaches of exciting plasmons consist of either using electrons (e.g., electron energy loss spectroscopy) or light (Kretchman and Otto geometry) while more recently plasmons have been excited even by single photons. A different approach: thermal excitation of a plasmon resonance at high temperatures using alternate plasmonic media was proposed by S. Molesky et al. [Opt. Express 21, A96–A110 (2013)]. Here, we show how the long-standing search for a high temperature narrowband near-field emitter for thermophotovoltaics can be fulfilled by thermally exciting plasmons. We also describe a method to control Wein's displacement law in the near-field using high temperature epsilon-near-zero metamaterials. Finally, we show that our work opens up an interesting direction of research for the field of slow light: thermal emission control.

  13. Plasmonic and photonic scattering and near fields of nanoparticles.

    PubMed

    Schmid, Martina; Andrae, Patrick; Manley, Phillip

    2014-01-01

    We theoretically compare the scattering and near field of nanoparticles from different types of materials, each characterized by specific optical properties that determine the interaction with light: metals with their free charge carriers giving rise to plasmon resonances, dielectrics showing zero absorption in wide wavelength ranges, and semiconductors combining the two beforehand mentioned properties plus a band gap. Our simulations are based on Mie theory and on full 3D calculations of Maxwell's equations with the finite element method. Scattering and absorption cross sections, their division into the different order electric and magnetic modes, electromagnetic near field distributions around the nanoparticles at various wavelengths as well as angular distributions of the scattered light were investigated. The combined information from these calculations will give guidelines for choosing adequate nanoparticles when aiming at certain scattering properties. With a special focus on the integration into thin film solar cells, we will evaluate our results. PMID:24475923

  14. Tip-enhanced Raman spectroscopy and near-field polarization

    NASA Astrophysics Data System (ADS)

    Saito, Yuika; Mino, Toshihiro; Verma, Prabhat

    2015-12-01

    Tip-enhanced Raman spectroscopy (TERS) is a powerful tool for High-resolution Raman spectroscopy. In this method, a metal coated nano-tip acts as a plasmonic antenna to enhance the originally weak Raman scattering from a nanometric volume of a sample. The technique enables to detect Raman scattering light from nano-scale area and also enhance the light intensity with combination of near-filed light and localized surface plasmon generated at a metallized tip apex. Nowadays TERS is used to investigate various nano-scale samples, for examples, carbon nanotubes, graphenes DNA and biomaterials. As the TERS developed, there is high demand to investigate the properties of near-field light e.g. polarization properties. We have analyzed the polarization properties of near-field light in TERS and successfully realized the quantitative nano-imaging by visible light.

  15. Probe Station and Near-Field Scanner for Testing Antennas

    NASA Technical Reports Server (NTRS)

    Zaman, Afroz; Lee, Richard Q.; Darby, William G.; Barr, Philip J.; Miranda, Felix A.; Lambert, Kevin

    2006-01-01

    A facility that includes a probe station and a scanning open-ended waveguide probe for measuring near electromagnetic fields has been added to Glenn Research Center's suite of antenna-testing facilities, at a small fraction of the cost of the other facilities. This facility is designed specifically for nondestructive characterization of the radiation patterns of miniaturized microwave antennas fabricated on semiconductor and dielectric wafer substrates, including active antennas that are difficult to test in traditional antenna-testing ranges because of fragility, smallness, or severity of DC-bias or test-fixture requirements. By virtue of the simple fact that a greater fraction of radiated power can be captured in a near-field measurement than in a conventional far-field measurement, this near-field facility is convenient for testing miniaturized antennas with low gains.

  16. Mars Pathfinder Near-Field Rock Distribution Re-Evaluation

    NASA Technical Reports Server (NTRS)

    Haldemann, A. F. C.; Golombek, M. P.

    2003-01-01

    We have completed analysis of a new near-field rock count at the Mars Pathfinder landing site and determined that the previously published rock count suggesting 16% cumulative fractional area (CFA) covered by rocks is incorrect. The earlier value is not so much wrong (our new CFA is 20%), as right for the wrong reason: both the old and the new CFA's are consistent with remote sensing data, however the earlier determination incorrectly calculated rock coverage using apparent width rather than average diameter. Here we present details of the new rock database and the new statistics, as well as the importance of using rock average diameter for rock population statistics. The changes to the near-field data do not affect the far-field rock statistics.

  17. Near-field effects of asteroid impacts in deep water

    SciTech Connect

    Gisler, Galen R; Weaver, Robert P; Gittings, Michael L

    2009-06-11

    Our previous work has shown that ocean impacts of asteroids below 500 m in diameter do not produce devastating long-distance tsunamis. Nevertheless, a significant portion of the ocean lies close enough to land that near-field effects may prove to be the greatest danger from asteroid impacts in the ocean. Crown splashes and central jets that rise up many kilometres into the atmosphere can produce, upon their collapse, highly non-linear breaking waves that could devastate shorelines within a hundred kilometres of the impact site. We present illustrative calculations, in two and three dimensions, of such impacts for a range of asteroid sizes and impact angles. We find that, as for land impacts, the greatest dangers from oceanic impacts are the short-term near-field, and long-term atmospheric effects.

  18. Plasmonic and photonic scattering and near fields of nanoparticles

    PubMed Central

    2014-01-01

    We theoretically compare the scattering and near field of nanoparticles from different types of materials, each characterized by specific optical properties that determine the interaction with light: metals with their free charge carriers giving rise to plasmon resonances, dielectrics showing zero absorption in wide wavelength ranges, and semiconductors combining the two beforehand mentioned properties plus a band gap. Our simulations are based on Mie theory and on full 3D calculations of Maxwell’s equations with the finite element method. Scattering and absorption cross sections, their division into the different order electric and magnetic modes, electromagnetic near field distributions around the nanoparticles at various wavelengths as well as angular distributions of the scattered light were investigated. The combined information from these calculations will give guidelines for choosing adequate nanoparticles when aiming at certain scattering properties. With a special focus on the integration into thin film solar cells, we will evaluate our results. PMID:24475923

  19. Near-field imaging of quantum cascade laser transverse modes.

    PubMed

    Yu, Nanfang; Diehl, Laurent; Cubukcu, Ertugrul; Pflügl, Christian; Bour, David; Corzine, Scott; Zhu, Jintian; Höfler, Gloria; Crozier, Kenneth B; Capasso, Federico

    2007-10-01

    We report near field imaging of the transverse lasing modes of quantum cascade lasers. A mid-infrared apertureless near-field scanning optical microscope was used to characterize the modes on the laser facet. A very stable mode pattern corresponding to a TM(00) mode was observed as function of increasing driving current for a narrow active region quantum cascade laser. Higher order modes were observed for devices with a larger active region width-to-wavelength ratio operated in pulsed mode close to threshold. A theoretical model is proposed to explain why specific transverse modes are preferred close to threshold. The model is in good agreement with the experimental results. PMID:19550591

  20. Technical basis and programmatic requirements for laboratory study of hydrological properties of the near-field environment

    SciTech Connect

    Lin, W.

    1993-10-01

    This document contains the technical basis and programmatic requirements for a study plant governs laboratory study of hydrological properties of the near-field environment of a nuclear waste repository. The Study Plan (SP), known as ``Near-Field Environment Hydrological Properties (NFEHP),`` will be reviewed by Yucca Mountain Site Characterization Project Office (YMPO) of the United States Department of Energy (DOE). The final version of the SP may be different from this document. The SP is identified by Work Breakdown Structure (WBS) as WBS 1.2.2.2.2. This study is described in Section 8.3.4.2.4.1 of the Site Characterization Plant (SCP). The purpose and objective of the Near-Field Environment Hydrological Properties study are to understand, at the laboratory scale, hydrological processes expected to occur within the near field of nuclear waste repository after waste package emplacement.

  1. Graphene-enhanced infrared near-field microscopy.

    PubMed

    Li, Peining; Wang, Tao; Böckmann, Hannes; Taubner, Thomas

    2014-08-13

    Graphene is a promising two-dimensional platform for widespread nanophotonic applications. Recent theories have predicted that graphene can also enhance evanescent fields for subdiffraction-limited imaging. Here, for the first time we experimentally demonstrate that monolayer graphene offers a 7-fold enhancement of evanescent information, improving conventional infrared near-field microscopy to resolve buried structures at a 500 nm depth with λ/11-resolution. PMID:25019504

  2. Near-Field Source Localization by Using Focusing Technique

    NASA Astrophysics Data System (ADS)

    He, Hongyang; Wang, Yide; Saillard, Joseph

    2008-12-01

    We discuss two fast algorithms to localize multiple sources in near field. The symmetry-based method proposed by Zhi and Chia (2007) is first improved by implementing a search-free procedure for the reduction of computation cost. We present then a focusing-based method which does not require symmetric array configuration. By using focusing technique, the near-field signal model is transformed into a model possessing the same structure as in the far-field situation, which allows the bearing estimation with the well-studied far-field methods. With the estimated bearing, the range estimation of each source is consequently obtained by using 1D MUSIC method without parameter pairing. The performance of the improved symmetry-based method and the proposed focusing-based method is compared by Monte Carlo simulations and with Crammer-Rao bound as well. Unlike other near-field algorithms, these two approaches require neither high-computation cost nor high-order statistics.

  3. Sample heating in near-field scanning optical microscopy

    NASA Astrophysics Data System (ADS)

    Erickson, Elizabeth S.; Dunn, Robert C.

    2005-11-01

    Heating near the aperture of aluminum coated, fiber optic near-field scanning optical microscopy probes was studied as a function of input and output powers. Using the shear-force feedback method, near-field probes were positioned nanometers above a thermochromic polymer and spectra were recorded as the input power was varied. Excitation at 405 nm of a thin polymer film incorporating perylene and N-allyl-N-methylaniline leads to dual emission peaks in the spectra. The relative peak intensity is temperature sensitive leading to a ratiometric measurement, which avoids complications based solely on intensity. Using this method, we find that the proximal end of typical near-field probes modestly increase in temperature to 40-45 °C at output powers of a few nanowatts (input power of ˜0.15mW). This increases to 55-65 °C at higher output powers of 50 nW or greater (input power of ˜2-4mW). Thermal heating of the probe at higher powers leads to probe elongation, which limits the heating experienced by the sample.

  4. Near-field photometry for organic light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Li, Rui; Harikumar, Krishnan; Isphording, Alexandar; Venkataramanan, Venkat

    2013-03-01

    Organic Light Emitting Diode (OLED) technology is rapidly maturing to be ready for next generation of light source for general lighting. The current standard test methods for solid state lighting have evolved for semiconductor sources, with point-like emission characteristics. However, OLED devices are extended surface emitters, where spatial uniformity and angular variation of brightness and colour are important. This necessitates advanced test methods to obtain meaningful data for fundamental understanding, lighting product development and deployment. In this work, a near field imaging goniophotometer was used to characterize lighting-class white OLED devices, where luminance and colour information of the pixels on the light sources were measured at a near field distance for various angles. Analysis was performed to obtain angle dependent luminous intensity, CIE chromaticity coordinates and correlated colour temperature (CCT) in the far field. Furthermore, a complete ray set with chromaticity information was generated, so that illuminance at any distance and angle from the light source can be determined. The generated ray set is needed for optical modeling and design of OLED luminaires. Our results show that luminance non-uniformity could potentially affect the luminaire aesthetics and CCT can vary with angle by more than 2000K. This leads to the same source being perceived as warm or cool depending on the viewing angle. As OLEDs are becoming commercially available, this could be a major challenge for lighting designers. Near field measurement can provide detailed specifications and quantitative comparison between OLED products for performance improvement.

  5. Complex Near-Field Plasmonic Response of Au Nanospirals

    NASA Astrophysics Data System (ADS)

    Hachtel, Jordan; Davidson, Roderick; Lupini, Andrew; Lawrie, Benjamin; Haglund, Richard; Pantelides, Sokrates

    Complex metallic nanostructures that support unique near-field surface plasmon modes have shown applications across the fields of photovoltaics, bio-sensing, and even quantum computing. Chiral Au nanospirals not only possess a non-symmetric morphology that results in second-harmonic generation, but possess multiple distinct near-field plasmonic modes that cover a wide range of plasmon frequencies. We use cathodoluminescence (CL) and electron energy loss spectroscopy (EELS) within a scanning transmission electron microscopy (STEM) to study the surface plasmons and map them with nanoscale precision. The two techniques are complementary as EELS measures excitations in the sample, while CL measures the subsequent radiative decays. We STEM-EELS/CL to map and analyze the spatial profile, intensity and polarization response of the intricate near-field plasmon modes in these versatile nanostructures. This work was funded by the Department of Energy Grant DE-FG02-09ER46554 and the Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division.

  6. Near-field thermal electromagnetic transport: An overview

    NASA Astrophysics Data System (ADS)

    Edalatpour, Sheila; DeSutter, John; Francoeur, Mathieu

    2016-07-01

    A general near-field thermal electromagnetic transport formalism that is independent of the size, shape and number of heat sources is derived. The formalism is based on fluctuational electrodynamics, where fluctuating currents due to thermal agitation are added to Maxwell's curl equations, and is thus valid for heat sources in local thermodynamic equilibrium. Using a volume integral formulation, it is shown that the proposed formalism is a generalization of the classical electromagnetic scattering framework in which thermal emission is implicitly assumed to be negligible. The near-field thermal electromagnetic transport formalism is afterwards applied to a problem involving three spheres with size comparable to the wavelength, where all multipolar interactions are taken into account. Using the thermal discrete dipole approximation, it is shown that depending on the dielectric function, the presence of a third sphere slightly affects the spatial distribution of power absorbed compared to the two-sphere case. A transient analysis shows that despite a non-uniform spatial distribution of power absorbed, the sphere temperature remains spatially uniform at any instant due to the fact that the thermal resistance by conduction is much smaller than the resistance by radiation. The formalism proposed in this paper is general, and could be used as a starting point for adapting solution methods employed in traditional electromagnetic scattering problems to near-field thermal electromagnetic transport.

  7. Improved optical fiber probes for scanning near field optical microscopy

    NASA Astrophysics Data System (ADS)

    Wheaton, Bryan R.

    2004-12-01

    The motivation behind this work stems from a combination of my interest in atomic force microscopy (AFM) and the need to apply AFM to several areas of glass research. AFM was used as the main characterization tool in the study of near-field scanning optical microscopy (NSOM) tip formation, evaluation of phase separation in glasses and copper oxide semiconductor film formation. The use of atomic force microscopy (AFM) to evaluate the evolving tip structure of an optical fiber probe for NSOM was studied. This study demonstrates the feasibility of predicting the final tip cone angle, without taking the etching process to completion. Cone angles reported in this study ranged from 58 to 152 degrees, depending on the fiber type and etch conditions. The ability to vary the probe cone angle, and utilize AFM to evaluate the cone angle that results from a set of etch conditions, are valuable additions to the development of NSOM fiber tips. The chemical and spatial variation of phase separated morphologies in glasses can range from a few angstroms to microns, often requiring very high magnification for detection. Historically phase separated glasses have been characterized by transmission electron microscopy (TEM), a time consuming and costly technique. Atomic force microscopy (AFM) provides an inexpensive alternative to TEM and has proven to be a powerful tool in the evaluation of type, degree and scale of phase separation in glasses down to the nanometer level. AFM was used to show that the thickness and uniformity of the CuO films grown in-situ on the surface of copper containing alkali borosilicate glasses increased with time and temperature, however an upper time limit was reached in which no further thickness increases were realized. Tenorite, cuprite and copper metal films were produced depending on the heat treatment environment. XPS was utilized to confirm that copper oxide film formation during heat treatments of glasses near Tg results from the oxidation of copper

  8. Hyperbolic metamaterial-based near-field thermophotovoltaic system for hundreds of nanometer vacuum gap.

    PubMed

    Jin, Seokmin; Lim, Mikyung; Lee, Seung S; Lee, Bong Jae

    2016-03-21

    Artificially designed hyperbolic metamaterial (HMM) possesses extraordinary electromagnetic features different from those of naturally existing materials. In particular, the dispersion relation of waves existing inside the HMM is hyperbolic rather than elliptical; thus, waves that are evanescent in isotropic media become propagating in the HMM. This characteristic of HMMs opens a novel way to spectrally control the near-field thermal radiation in which evanescent waves in the vacuum gap play a critical role. In this paper, we theoretically investigate the performance of a near-field thermophotovoltaic (TPV) energy conversion system in which a W/SiO2-multilayer-based HMM serves as the emitter at 1000 K and InAs works as the TPV cell at 300 K. By carefully designing the thickness of constituent materials of the HMM emitter, the electric power of the near-field TPV devices can be increased by about 6 times at 100-nm vacuum gap as compared to the case of the plain W emitter. Alternatively, in regards to the electric power generation, HMM emitter at experimentally achievable 100-nm vacuum gap performs equivalently to the plain W emitter at 18-nm vacuum gap. We show that the enhancement mechanism of the HMM emitter is due to the coupled surface plasmon modes at multiple metal-dielectric interfaces inside the HMM emitter. With the minority carrier transport model, the optimal p-n junction depth of the TPV cell has also been determined at various vacuum gaps. PMID:27136882

  9. Optical near-field investigations of individual single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Hartschuh, Achim

    2009-03-01

    Optical excitation of semiconducting nanotubes creates excitons that determine nearly all light-based applications. Near-field photoluminescence (PL) and Raman imaging with a spatial resolution better than 15 nm was used to probe the spectroscopic properties of excitonic states along single nanotubes on substrates [1,2]. The PL intensity was found to decrease towards the nanotube ends on a length scale of few 10 nm probably caused by exciton transport to localized end states followed by efficient non-radiative recombination. DNA-wrapping of nanotubes results in pronounced emission energy variations on a length scale of few 10 nm indicating the potential of the material for nanoscale sensing applications [3]. Inter-nanotube energy transfer was studied for different pairs of semiconducting nanotubes forming bundles and crossings [4]. Efficient transfer is found to be limited to a few nanometres because of competing fast non-radiative relaxation and can be explained in terms of electromagnetic near-field coupling. We also report on our recent experimental results on time-resolved near-field PL measurements, electrically gated nanotubes and the PL of nanotubes on metal surfaces. [4pt] References: [0pt] [1] A. Hartschuh, Angew. Chem. Int. Ed. 47, 8178 (2008). [0pt] [2] I. O. Maciel et. al, Nature Mat. 7, 878 (2008). [0pt] [3] H. Qian et. al, Nano Lett. 8, 2706 (2008). [0pt] [4] H. Qian et. al, Nano Lett. 8, 1363 (2008).

  10. Phase interpretation for polarization-dependent near-field images of high-density gratings

    NASA Astrophysics Data System (ADS)

    Zheng, Jiangjun; Zhou, Changhe; Wang, Bo

    2008-06-01

    It has been described that the near-field images of a high-density grating at the half self-imaging distance could be different for TE and TM polarization states. We propose that the phases of the diffraction orders play an important role in such polarization dependence. The view is verified through the coincidence of the numerical result of finite-difference time-domain method and the reconstructed results from the rigorous coupled-wave analysis. Field distributions of TE and TM polarizations are given numerically for a grating with period d = 2.3 λ, which are verified through experiments with the scanning near-field optical microscopy technique. The concept of phase interpretation not only explains the polarization dependence at the half self-imaging distance of gratings with a physical view, but also, it could be widely used to describe the near-field diffraction of a variety of periodic diffractive optical elements whose feature size comparable to the wavelength.

  11. On the slow dynamics of near-field acoustically levitated objects under High excitation frequencies

    NASA Astrophysics Data System (ADS)

    Ilssar, Dotan; Bucher, Izhak

    2015-10-01

    This paper introduces a simplified analytical model describing the governing dynamics of near-field acoustically levitated objects. The simplification converts the equation of motion coupled with the partial differential equation of a compressible fluid, into a compact, second order ordinary differential equation, where the local stiffness and damping are transparent. The simplified model allows one to more easily analyse and design near-field acoustic levitation based systems, and it also helps to devise closed-loop controller algorithms for such systems. Near-field acoustic levitation employs fast ultrasonic vibrations of a driving surface and exploits the viscosity and the compressibility of a gaseous medium to achieve average, load carrying pressure. It is demonstrated that the slow dynamics dominates the transient behaviour, while the time-scale associated with the fast, ultrasonic excitation has a small presence in the oscillations of the levitated object. Indeed, the present paper formulates the slow dynamics under an ultrasonic excitation without the need to explicitly consider the latter. The simplified model is compared with a numerical scheme based on Reynolds equation and with experiments, both showing reasonably good results.

  12. Coupling entropy of co-processing model on social networks

    NASA Astrophysics Data System (ADS)

    Zhang, Zhanli

    2015-08-01

    Coupling entropy of co-processing model on social networks is investigated in this paper. As one crucial factor to determine the processing ability of nodes, the information flow with potential time lag is modeled by co-processing diffusion which couples the continuous time processing and the discrete diffusing dynamics. Exact results on master equation and stationary state are achieved to disclose the formation. In order to understand the evolution of the co-processing and design the optimal routing strategy according to the maximal entropic diffusion on networks, we propose the coupling entropy comprehending the structural characteristics and information propagation on social network. Based on the analysis of the co-processing model, we analyze the coupling impact of the structural factor and information propagating factor on the coupling entropy, where the analytical results fit well with the numerical ones on scale-free social networks.

  13. Unified theory of near-field analysis and measurement - Scattering and inverse scattering

    NASA Astrophysics Data System (ADS)

    Wacker, P. F.

    1981-03-01

    The scanning procedures of unified theory of near-field analysis and measurement are adapted to the determination of scattering patterns of electromagnetic and scalar systems from measurements made in the near, intermediate, or far field, with emphasis on high accuracy and efficient data processing. The scanning procedures include spherical, improved plane polar, and many types of plane rectangular, plane radial, and circular cylindrical scanning. Application of group representation to inverse scattering analysis is discussed.

  14. Atomic Response in the Near-Field of Nanostructured Plasmonic Metamaterial.

    PubMed

    Aljunid, Syed Abdullah; Chan, Eng Aik; Adamo, Giorgio; Ducloy, Martial; Wilkowski, David; Zheludev, Nikolay I

    2016-05-11

    We report on reflection spectra of cesium atoms in close vicinity of a nanostructured metallic meta-surface. We show that the hyperfine sub-Doppler spectrum of the 6(2)S1/2-6(2)P3/2 resonance transition at 852 nm is strongly affected by the coupling to the plasmonic resonance of the nanostructure. Fine tuning of dispersion and positions of the atomic lines in the near-field of plasmonic metamaterials could have uses and implications for atom-based metrology, sensing, and the development of atom-on-a-chip devices. PMID:27018806

  15. Quantitative and Direct Near-Field Analysis of Plasmonic-Induced Transparency and the Observation of a Plasmonic Breathing Mode.

    PubMed

    Khunsin, Worawut; Dorfmüller, Jens; Esslinger, Moritz; Vogelgesang, Ralf; Rockstuhl, Carsten; Etrich, Christoph; Kern, Klaus

    2016-02-23

    We investigated experimentally and numerically in the optical near-field a plasmonic model system similar to a dolmen-type structure for phenomena such as plasmon-induced transparency. Through engineering of coupling strength, structure orientation, and incident angle and phase of the excitation source it was possible to control near-field excitation of the dark modes. We showed that quantitative analysis of near-field amplitude and excitation strength provided essential information that allowed identifying the interaction between the bright and the dark mode and how it causes the formation of plasmon-induced transparency features and a Fano resonance. In addition, we introduced a mechanism to excite field distributions in plasmonic structures that cannot be accessed directly using far-field illumination and demonstrated the excitation of a dark mode akin to a symmetry-forbidden plasmonic breathing mode using a linearly polarized far-field source. PMID:26789080

  16. Concurrent polarization retrieval in multi-heterodyne scanning near-field optical microscopy: validation on silicon form-birefringent grating.

    PubMed

    Yu, L; Sfez, T; Paeder, V; Stenberg, P; Nakagawa, W; Kuittinen, M; Herzig, H P

    2012-10-01

    We demonstrate a concurrent polarization-retrieval algorithm based on a multi-heterodyne scanning near-field optical microscopy (MH-SNOM) measurement system. This method relies on calibration of the polarization properties of the MH-SNOM using an isotropic region of the sample in the vicinity of the nanostructures of interest. We experimentally show the effectiveness of the method on a silicon form-birefringent grating (FBG) with significant polarization diversity. Three spatial dimensional near-field measurements are in agreement with theoretical predictions obtained with rigorous coupled-wave analysis (RCWA). Pseudo-far-field measurements are performed to obtain the effective refractive index of the FBG, emphasizing the validity of the proposed method. This reconstruction algorithm makes the MH-SNOM a powerful tool to analyze concurrently the polarization-dependent near-field optical response of nanostructures with sub wavelength resolution as long as a calibration area is available in close proximity. PMID:23188273

  17. Decision making based on optical excitation transfer via near-field interactions between quantum dots

    NASA Astrophysics Data System (ADS)

    Naruse, Makoto; Nomura, Wataru; Aono, Masashi; Ohtsu, Motoichi; Sonnefraud, Yannick; Drezet, Aurélien; Huant, Serge; Kim, Song-Ju

    2014-10-01

    Optical near-field interactions between nanostructured matters, such as quantum dots, result in unidirectional optical excitation transfer when energy dissipation is induced. This results in versatile spatiotemporal dynamics of the optical excitation, which can be controlled by engineering the dissipation processes and exploited to realize intelligent capabilities such as solution searching and decision making. Here, we experimentally demonstrate the ability to solve a decision making problem on the basis of optical excitation transfer via near-field interactions by using colloidal quantum dots of different sizes, formed on a geometry-controlled substrate. We characterize the energy transfer behavior due to multiple control light patterns and experimentally demonstrate the ability to solve the multi-armed bandit problem. Our work makes a decisive step towards the practical design of nanophotonic systems capable of efficient decision making, one of the most important intellectual attributes of the human brain.

  18. Exact Reconstruction for Near-Field Three-Dimensional Planar Millimeter-Wave Holographic Imaging

    NASA Astrophysics Data System (ADS)

    Qiao, Lingbo; Wang, Yingxin; Zhao, Ziran; Chen, Zhiqiang

    2015-12-01

    In this paper, an exact reconstruction formula is presented for near-field three-dimensional (3D) planar millimeter-wave (MMW) holographic imaging. The proposed formula is derived based on scalar diffraction theory, and the round-trip imaging process is equivalent to a unidirectional optical field propagation. Because of compensating the propagation loss of the source for the near-field imaging configuration, the inconsistency in range domain of the reconstructed 3D images is avoided. The proposed reconstruction formula also gives a phase correction for the reconstructed complex-valued reflectivity of the target and the range coordinate can be exactly determined. Simulations and laboratory imaging experiments are performed to demonstrate the effectiveness of the proposed reconstruction formula.

  19. Decision making based on optical excitation transfer via near-field interactions between quantum dots

    SciTech Connect

    Naruse, Makoto; Nomura, Wataru; Ohtsu, Motoichi; Aono, Masashi; Sonnefraud, Yannick; Drezet, Aurélien; Huant, Serge; Kim, Song-Ju

    2014-10-21

    Optical near-field interactions between nanostructured matters, such as quantum dots, result in unidirectional optical excitation transfer when energy dissipation is induced. This results in versatile spatiotemporal dynamics of the optical excitation, which can be controlled by engineering the dissipation processes and exploited to realize intelligent capabilities such as solution searching and decision making. Here, we experimentally demonstrate the ability to solve a decision making problem on the basis of optical excitation transfer via near-field interactions by using colloidal quantum dots of different sizes, formed on a geometry-controlled substrate. We characterize the energy transfer behavior due to multiple control light patterns and experimentally demonstrate the ability to solve the multi-armed bandit problem. Our work makes a decisive step towards the practical design of nanophotonic systems capable of efficient decision making, one of the most important intellectual attributes of the human brain.

  20. Cryogenic Near-Field Microscopy in Correlated Electronic Systems

    NASA Astrophysics Data System (ADS)

    Gozar, Adrian

    2015-03-01

    We present results on the performance of a scattering-based scanning near-field optical microscope. The instrument was designed for measuring nano-scale complex dielectric properties of materials in a variable-temperature environment. The setup has a 20 - 30 nm spatial resolution with sample temperatures in the 10 - 300 K range. Spectral operation is in the infrared to visible and 0.1 - 1 THz regions. We illustrate these capabilities with results in graphene and ultra-thin sub-surface oxide films.

  1. Near-field spillover from a subreflector: Theory and experiment

    NASA Technical Reports Server (NTRS)

    Lee, S. W.; Acosta, R.; Cherrette, A. R.; Lam, P. T.

    1986-01-01

    In a dual reflector antenna, the spillover from the subreflector is important in determining the accuracy of near-field measurements. This is especially so when some of the feed elements are placed far away from the focus. In this paper, we present a high-frequency GTD analysis of the spillover field over a plane just behind the subreflector. Special attention is given to the field near the incident shadow boundary and the role played by the slope diffraction term. Our computations are in excellent agreement with experimental results.

  2. Magnetic dipole moment determination by near-field analysis

    NASA Technical Reports Server (NTRS)

    Eichhorn, W. L.

    1972-01-01

    A method for determining the magnetic moment of a spacecraft from magnetic field data taken in a limited region of space close to the spacecraft. The spacecraft's magnetic field equations are derived from first principles. With measurements of this field restricted to certain points in space, the near-field equations for the spacecraft are derived. These equations are solved for the dipole moment by a least squares procedure. A method by which one can estimate the magnitude of the error in the calculations is also presented. This technique was thoroughly tested on a computer. The test program is described and evaluated, and partial results are presented.

  3. Focusing properties of near-field time reversal

    NASA Astrophysics Data System (ADS)

    de Rosny, Julien; Fink, Mathias

    2007-12-01

    A time-reversal mirror (TRM) is a plane apparatus that generates the time symmetric of a wave produced by an initial source. Here we look for the conditions to obtain subwavelength focusing when the initial source is in the near field of the TRM and the propagating medium is homogeneous and isotropic. Three variants of TRM are studied: TRM made of monopoles, dipoles, or both of them. The analysis is performed in terms of evanescent and propagative waves. We conclude that only the dipole-TRM leads to subwavelength focusing.

  4. Focusing properties of near-field time reversal

    SciTech Connect

    Rosny, Julien de; Fink, Mathias

    2007-12-15

    A time-reversal mirror (TRM) is a plane apparatus that generates the time symmetric of a wave produced by an initial source. Here we look for the conditions to obtain subwavelength focusing when the initial source is in the near field of the TRM and the propagating medium is homogeneous and isotropic. Three variants of TRM are studied: TRM made of monopoles, dipoles, or both of them. The analysis is performed in terms of evanescent and propagative waves. We conclude that only the dipole-TRM leads to subwavelength focusing.

  5. Simulation study of 'perfect lens' for near-field nanolithography

    NASA Astrophysics Data System (ADS)

    Guo, Xiaowei; Dong, Qiming; Liu, Yong

    2011-09-01

    The near-field perfect lens (NFPL) in imaging chrome gratings is investigated by using finite difference time domain (FDTD) method. The surface plasmon focused effect in and beneath the NFPL layer is demonstrated. The effects of the grating parameters and NFPL permittivity on image fidelity are explored. It is found that the excitation of surface plasmons results in frequency-increased images at large duty cycles and small imaginary part of NFPL permittivities. It is also shown that maximum intensity distributions on image plane occur at some specified pitches and duty cycles. The physics mechanisms are presented to explain these phenomena.

  6. Determination of near field excavation disturbance in crystalline rock

    SciTech Connect

    Koopmans, R.; Hughes, R.W.

    1986-01-01

    The computerized dilatometer system has rapidly and economically provided deformation moduli of low and high modulus rock, determined the extent of excavation disturbance surrounding an underground opening and located open fracture within a rock mass. Results from both test sites indicate that the moduli obtained were influenced by the in situ tangential stress field. It has been shown that the near field excavation disturbance is kept to a minimum through the use of careful excavation techniques such as the tunnel boring machine. In turn, the in situ tangential stress levels and deformation moduli are maximized while the corresponding permeability is minimized.

  7. Near Field Imaging at Microwave and Millemeter Wave Frequencies

    SciTech Connect

    Sheen, David M.; McMakin, Douglas L.; Hall, Thomas E.

    2007-06-03

    Near field imaging at microwave and millimeter wave frequencies is useful for a wide variety of applications including concealed weapon detection, through-wall and inner-wall imaging, ground penetrating radar imaging, radar cross section analysis, and non-destructive evaluation of materials. A variety of novel imaging techniques have been developed for many of these applications at the Pacific Northwest National Laboratory (PNNL) . These techniques make use of wideband holographic wavefront reconstruction methods, and have been developed to optimize the image quality and resolution. This paper will summarize several of these techniques and show imaging results for several interesting application areas.

  8. Micromachined photoplastic probe for scanning near-field optical microscopy

    NASA Astrophysics Data System (ADS)

    Genolet, G.; Despont, M.; Vettiger, P.; Staufer, U.; Noell, W.; de Rooij, N. F.; Cueni, T.; Bernal, M.-P.; Marquis-Weible, F.

    2001-10-01

    We present a hybrid probe for scanning near-field optical microscopy (SNOM), which consists of a micromachined photoplastic tip with a metallic aperture at the apex that is attached to an optical fiber, thus combining the advantages of optical fiber probes and micromachined tips. The tip and aperture are batch fabricated and assembled to a preetched optical fiber with micrometer centering precision. Rectangular apertures of 50 nm×130 nm have been produced without the need of any postprocessing. Topographical and optical imaging with a probe having an aperture of 300 nm demonstrate the great potential of the photoplastic probe for SNOM applications.

  9. Plasmonic lithography modeling and measurement of near-field distribution of plasmonic nano-aperture

    NASA Astrophysics Data System (ADS)

    Kim, Yongwoo; Kim, Seok; Jung, Howon; Jang, Jinhee; Lee, Jae Yong; Hahn, Jae W.

    2012-03-01

    In plasmonic nano lithography, a photoresist responds to the localized electric field which decays evanescently in the direction of depth. A simple analytic model is suggested to predict profiles of exposed and finally developed pattern with a finite contrast of photoresist. In this model, the developing process is revisited by accounting the variation of dissolution rate with respect to expose dose distribution. We introduce the concept of nominal developing thickness (NDT) to determine the optimized developing process fitting to the isointensity profile. Based on this model, we obtained three dimensional distribution of near-field of bowtie shaped plasmonic nano aperture in a metal film from the near-field lithography pattern profile. For the near-field exposure, we fabricated a nano aperture in a aluminum metal film which is coated on the contact probe tip. By illuminating 405 nm diode laser source, the positive type photoresist is exposed by the localized electric field produced by nano aperture. The exposed photoresist is developed by the TMAH based solution with a optimum NDT, which leads the developing march encounters the isoexposure contour at threshold dose. From the measurement of developed pattern profile with a atomic force microscope (AFM), the three-dimensional isoexposure (or iso-intensity) surface at the very near region from the exit plane of an aperture (depth: 5 ~ 50 nm) is profiled. Using the threshold dose of photoresist and exposure time, the absolute intensity level is also measured. The experimental results are quantitatively compared with the calculation of FDTD (finite- difference time-domain) method. Concerning with the error in exposure time and threshold dose value, the error in measurement of profile and intensity are less than 6% and 1%, respectively. We expect the lithography model described in this presentation allows more elaborated expectation of developed pattern profile. Furthermore, a methodology of mapping is useful for the

  10. Aeroacoustic near-field measurements with microscale resolution

    NASA Astrophysics Data System (ADS)

    Haufe, D.; Pietzonka, S.; Schulz, A.; Bake, F.; Enghardt, L.; Czarske, J. W.; Fischer, A.

    2014-10-01

    In order to analyse aeroacoustic phenomena at near-fields, e.g. the sound-flow interaction at aircraft engine liners, measurements of the flow velocity and the acoustic particle velocity (APV) with microscale resolution are required. To this end, the APV measurement with a high spatial resolution of 10 µm was conducted by means of a laser Doppler velocity profile sensor. For validation of the APV measurements using the profile sensor in a superposed flow, a good agreement with indirect microphone measurements as a reference was achieved, up to a maximum Mach number of 0.25. Aeroacoustic measurements at a minimum distance of 350 µm to the perforation of a bias flow liner were performed using the profile sensor. As a result, acoustically induced velocity oscillations near the rim of the orifice were detected with microscale resolution. The phase-resolved oscillation field indicates vortex shedding from the perforation, which is initiated by the sound-flow interaction. Thus, it is demonstrated that the profile sensor is a valuable tool for analysing aeroacoustic phenomena at near-fields, down to the Kolmogorov scale.

  11. Unidirectional wireless power transfer using near-field plates

    NASA Astrophysics Data System (ADS)

    Imani, Mohammadreza F.; Grbic, Anthony

    2015-05-01

    One of the obstacles preventing wireless power transfer from becoming ubiquitous is their leakage of power: high-amplitude electromagnetic fields that can interfere with other electronic devices, increase health concerns, or hinder power metering. In this paper, we present near-field plates (NFPs) as a novel method to tailor the electromagnetic fields generated by a wireless power transfer system while maintaining high efficiency. NFPs are modulated arrays or surfaces designed to form prescribed near-field patterns. The NFP proposed in this paper consists of an array of loaded loops that are designed to confine the electromagnetic fields of a resonant transmitting loop to the desired direction (receiving loop) while suppressing fields in other directions. The step-by-step design procedure for this device is outlined. Two NFPs are designed and examined in full-wave simulation. Their performance is shown to be in close agreement with the design predictions, thereby verifying the proposed design and operation. A NFP is also fabricated and experimentally shown to form a unidirectional wireless power transfer link with high efficiency.

  12. Near-Field Microscopy Studies of Lung Surfactant Collapse

    NASA Astrophysics Data System (ADS)

    Aga, Rachel; Dunn, Robert

    2003-03-01

    Respiratory distress syndrome (RDS), the fourth leading cause of infant mortality in the United States, arises from an insufficiently developed lung surfactant (LS). Healthy LS, a mixture of lipids and proteins that coats the inner surface of the lungs, reduces the alveolar surface tension to a few millinewtons per meter and, thus, facilitates breathing by stabilizing the large surface area changes associated with respiration. In the absence of an effective LS, surfactant collapse pressure (i.e., monolayer compressibility) and the ability of the monolayer to re-spread during the breathing cycle are reduced, resulting in labored breathing, reduced oxygen transport, and often death in those afflicted. In this study, we investigate the mechanism of collapse and re-spreading of a monolayer formed by a replacement surfactant commonly used in treatment of RDS. Through confocal microscopy fluorescence images obtained at a series of pressures near collapse, we find evidence for multilayer formation in the films. A further understanding of the collapse mechanism is obtained by comparing high resolution fluorescence and topography information measured with near-field scanning optical microscopy. The combined data from both confocal and near-field measurements are used to develop a model of lung surfactant collapse and re-spreading.

  13. Unidirectional wireless power transfer using near-field plates

    SciTech Connect

    Imani, Mohammadreza F.; Grbic, Anthony

    2015-05-14

    One of the obstacles preventing wireless power transfer from becoming ubiquitous is their leakage of power: high-amplitude electromagnetic fields that can interfere with other electronic devices, increase health concerns, or hinder power metering. In this paper, we present near-field plates (NFPs) as a novel method to tailor the electromagnetic fields generated by a wireless power transfer system while maintaining high efficiency. NFPs are modulated arrays or surfaces designed to form prescribed near-field patterns. The NFP proposed in this paper consists of an array of loaded loops that are designed to confine the electromagnetic fields of a resonant transmitting loop to the desired direction (receiving loop) while suppressing fields in other directions. The step-by-step design procedure for this device is outlined. Two NFPs are designed and examined in full-wave simulation. Their performance is shown to be in close agreement with the design predictions, thereby verifying the proposed design and operation. A NFP is also fabricated and experimentally shown to form a unidirectional wireless power transfer link with high efficiency.

  14. Key issues influencing the performance of near-field barriers

    SciTech Connect

    Tasker, P.W.; Wisbey, S.J.; Boyle, C.B.

    1993-12-31

    In developing a national strategy for the disposal of radioactive wastes, each country will consider isolation options that are appropriate to the types of waste that are produced. The options are developed in response to specific national regulatory requirements, and thus will focus on different aspects of performance. However, there are a number of technical concerns that are common to all programmes. The major issues concerning the behavior of the chemical and physical barriers in the near field of a radioactive waste repository are discussed in this paper. The description of key issue has been divided into the following categories: barrier design, barrier evolution, scientific understanding through modelling, and validation of performance. The near-field barriers are selected and designed to provide appropriate radionuclide containment and control. Factors affecting the evolution of these barriers, such as container degradation and gas generation, determine the subsequent release of radionuclides to the human environment. Modelling repository evolution is therefore an integral feature of performance assessments, and issues such as the treatment of inhomogeneities and non-equilibrium chemistry may need to be addressed. However, the use of mathematical and computer models implies a requirement for validation. The use of demonstration experiments and natural analogues builds confidence in the predictions of repository performance models, and provides a degree of validation for otherwise inaccessible timescales.

  15. Thermodynamically coupled mass transport processes in a saturated clay

    SciTech Connect

    Carnahan, C.L.

    1984-11-01

    Gradients of temperature, pressure, and fluid composition in saturated clays give rise to coupled transport processes (thermal and chemical osmosis, thermal diffusion, ultrafiltration) in addition to the direct processes (advection and diffusion). One-dimensional transport of water and a solute in a saturated clay subjected to mild gradients of temperature and pressure was simulated numerically. When full coupling was accounted for, volume flux (specific discharge) was controlled by thermal osmosis and chemical osmosis. The two coupled fluxes were oppositely directed, producing a point of stagnation within the clay column. Solute flows were dominated by diffusion, chemical osmosis, and thermal osmosis. Chemical osmosis produced a significant flux of solute directed against the gradient of solute concentration; this effect reduced solute concentrations relative to the case without coupling. Predictions of mass transport in clays at nuclear waste repositories could be significantly in error if coupled transport processes are not accounted for. 14 references, 8 figures, 1 table.

  16. Fostering new relational experience: clinical process in couple psychotherapy.

    PubMed

    Marmarosh, Cheri L

    2014-03-01

    One of the most critical goals for couple psychotherapy is to foster a new relational experience in the session where the couple feels safe enough to reveal more vulnerable emotions and to explore their defensive withdrawal, aggressive attacking, or blaming. The lived intimate experience in the session offers the couple an opportunity to gain integrative insight into their feelings, expectations, and behaviors that ultimately hinder intimacy. The clinical processes that are necessary include empathizing with the couple and facilitating safety within the session, looking for opportunities to explore emotions, ruptures, and unconscious motivations that maintain distance in the relationship, and creating a new relational experience in the session that has the potential to engender integrative insight. These clinical processes will be presented with empirical support. Experts from a session will be used to highlight how these processes influence the couple and promote increased intimacy. (PsycINFO Database Record (c) 2014 APA, all rights reserved). PMID:24059733

  17. Process for fabricating a charge coupled device

    DOEpatents

    Conder, Alan D.; Young, Bruce K. F.

    2002-01-01

    A monolithic three dimensional charged coupled device (3D-CCD) which utilizes the entire bulk of the semiconductor for charge generation, storage, and transfer. The 3D-CCD provides a vast improvement of current CCD architectures that use only the surface of the semiconductor substrate. The 3D-CCD is capable of developing a strong E-field throughout the depth of the semiconductor by using deep (buried) parallel (bulk) electrodes in the substrate material. Using backside illumination, the 3D-CCD architecture enables a single device to image photon energies from the visible, to the ultra-violet and soft x-ray, and out to higher energy x-rays of 30 keV and beyond. The buried or bulk electrodes are electrically connected to the surface electrodes, and an E-field parallel to the surface is established with the pixel in which the bulk electrodes are located. This E-field attracts charge to the bulk electrodes independent of depth and confines it within the pixel in which it is generated. Charge diffusion is greatly reduced because the E-field is strong due to the proximity of the bulk electrodes.

  18. Phase transformations coupled to deformation processes

    NASA Astrophysics Data System (ADS)

    Lookman, Turab

    2013-06-01

    Phase transformation processes have a substantial impact on the inelastic and damage response of materials. Yet, our understanding of how different loading conditions affect volume fractions of transformed phases, microstructure and transformation pathways is very much in its infancy. With an emphasis on distilling single crystal physics that can, in principle, be incorporated into higher length scale models, I will discuss how recent atomistic simulations on Ti are beginning to provide insights into transformation pathways and the interplay of phase transformations and deformation processes. These simulations are complemented by shock experiments on Zr, Ti together with characterization studies at the Advanced Photon Source.

  19. Quantitative Imaging of Rapidly Decaying Evanescent Fields Using Plasmonic Near-Field Scanning Optical Microscopy

    PubMed Central

    Zhang, Zhen; Ahn, Phillip; Dong, Biqin; Balogun, Oluwaseyi; Sun, Cheng

    2013-01-01

    Non-propagating evanescent fields play an important role in the development of nano-photonic devices. While detecting the evanescent fields in far-field can be accomplished by coupling it to the propagating waves, in practice they are measured in the presence of unwanted propagating background components. It leads to a poor signal-to-noise ratio and thus to errors in quantitative analysis of the local evanescent fields. Here we report on a plasmonic near-field scanning optical microscopy (p-NSOM) technique that incorporates a nanofocusing probe for adiabatic focusing of propagating surface plasmon polaritons at the probe apex, and for enhanced coupling of evanescent waves to the far-field. In addition, a harmonic demodulation technique is employed to suppress the contribution of the background. Our experimental results show strong evidence of background free near-field imaging using the new p-NSOM technique. Furthermore, we present measurements of surface plasmon cavity modes, and quantify their contributing sources using an analytical model. PMID:24076563

  20. Near-field localization by two dimensional metallic nano-post arrays with ultrashort light pulses

    NASA Astrophysics Data System (ADS)

    Lee, Hongki; Kim, Chulhong; Kim, Donghyun

    2016-03-01

    Locally amplified near-fields can be induced with nanostructures within a sub-diffraction-limited volume, which is useful for biomedical imaging and sensing applications. Employment of field localization in the biomedical applications where the pulsed light is used necessitates the spatial and temporal characteristics of fields near nanostructures. We considered the gold nano-post arrays of three different shapes to localize the near-fields which are circular, rhombic, and triangular. They were modeled to be located on an ITO film and a quartz substrate with periods changing from 300 to 900 nm by 200 nm. Their size changes from 50 to 250 nm which corresponds to the radius for the case of circular nanoposts and the distance between the center and the vertices for equilateral rhombic and triangular nanoposts. Numerical calculation of near-fields at the top of nanoposts was performed with finite difference time domain method when the Gaussian pulses at center wavelengths of 532, 633, and 850 nm were normally incident. Near-fields localization occurred mainly at vertices of the nanoposts, which makes the triangular nanoposts of primary interest with an observation of the strongest field intensity within a diffraction limited field-of-view. The observed fields on the triangular vertices were enhanced by 7.85, 51.54, and 7268 when the center wavelengths were 532, 633, and 850 nm respectively. Their temporal peaks were delayed by 2.05, 4.03, and 14.49 fs, which indicates the correlation between field enhancement and time delay associated with electron damping process. It was shown that with rhombic and triangular nanoposts fields can be localized below 10 nm on vertices and their signal-to-noise ratio increased with a larger period.

  1. Plasmonic electric near-field enhancement in self-organized gold nanoparticles in macroscopic arrays

    NASA Astrophysics Data System (ADS)

    Mondes, V.; Antonsson, E.; Plenge, J.; Raschpichler, C.; Halfpap, I.; Menski, A.; Graf, C.; Kling, M. F.; Rühl, E.

    2016-06-01

    When plasmonic nanoparticles are incorporated into nanostructures and they are exposed to external optical fields, plasmonic coupling causes electric near-field enhancement which is significantly larger than that of isolated nanoparticles. We report on the plasmonic coupling in arrays of gold nanospheres (20 ± 3 and 50 ± 4 nm) prepared by colloidal chemistry and self-organization. This yields field enhancement in arrays with areas of several mm2 and provides an alternative approach to lithographic methods for preparation of nanostructures for plasmonic applications. Gold nanospheres are surface-functionalized by organic ligands, which define the interparticle distance in the array upon self-organization of the nanoparticles. The experiments are accompanied by finite-difference time-domain simulations, which quantify the dependence of the field enhancement on the interparticle distance.

  2. Near-field photocurrent nanoscopy on bare and encapsulated graphene

    PubMed Central

    Woessner, Achim; Alonso-González, Pablo; Lundeberg, Mark B.; Gao, Yuanda; Barrios-Vargas, Jose E.; Navickaite, Gabriele; Ma, Qiong; Janner, Davide; Watanabe, Kenji; Cummings, Aron W.; Taniguchi, Takashi; Pruneri, Valerio; Roche, Stephan; Jarillo-Herrero, Pablo; Hone, James; Hillenbrand, Rainer; Koppens, Frank H. L.

    2016-01-01

    Optoelectronic devices utilizing graphene have demonstrated unique capabilities and performances beyond state-of-the-art technologies. However, requirements in terms of device quality and uniformity are demanding. A major roadblock towards high-performance devices are nanoscale variations of the graphene device properties, impacting their macroscopic behaviour. Here we present and apply non-invasive optoelectronic nanoscopy to measure the optical and electronic properties of graphene devices locally. This is achieved by combining scanning near-field infrared nanoscopy with electrical read-out, allowing infrared photocurrent mapping at length scales of tens of nanometres. Using this technique, we study the impact of edges and grain boundaries on the spatial carrier density profiles and local thermoelectric properties. Moreover, we show that the technique can readily be applied to encapsulated graphene devices. We observe charge build-up near the edges and demonstrate a solution to this issue. PMID:26916951

  3. Numerical calculations of ultrasonic fields I: transducer near fields

    SciTech Connect

    Johnson, J.A.

    1982-03-01

    A computer code for the calculation of linear acoustic wave propagation in homogeneous fluid and solid materials has been derived from the thermal-hydraulics code STEALTH. The code uses finite-difference techniques in a two-dimensional mesh made up of arbitrarily shaped quadrilaterals. Problems with two-dimensional plane strain or two-dimensional axial symmetries can be solved. Free, fixed, or stressed boundaries can be used. Transducers can be modeled by time dependent boundary conditions or by moving pistons. This paper gives a brief description of the method and shows the results of the calculation of the near fields of circular flat and focused transducers. These results agree with analytic theory along the axis of symmetry and with other codes that use a Huygens reconstruction technique off-axis.

  4. Numerical calculations of ultrasonic fields I: transducer near fields

    SciTech Connect

    Johnson, J.A.

    1982-04-01

    A computer code for the calculation of linear acoustic wave propagation in homogeneous fluid and solid materials has been derived from the thermal-hydraulics code STEALTH. The code uses finite-difference techniques in a two dimensional mesh made up of arbitrarily shaped quadrilaterals. Problems with two dimensional plane strain or two dimensional axial symmetries can be solved. Free, fixed or stressed boundaries can be used. Transducers can be modeled by time dependent boundary conditions or by moving pistons. A brief description of the method is given and the results of the calculation of the near fields of circular flat and focused transducers are shown. These results agree with analytic theory along the axis of symmetry and with other codes that use a Huygens' reconstruction technique off axis.

  5. Directional generation of graphene plasmons by near field interference.

    PubMed

    Wang, Lei; Cai, Wei; Zhang, Xinzheng; Xu, Jingjun; Luo, Yongsong

    2016-08-22

    The highly unidirectional excitation of graphene plasmons (GPs) through near-field interference of orthogonally polarized dipoles is investigated. The preferred excitation direction of GPs by a circularly polarized dipole can be simply understood with the angular momentum conservation law. Moreover, the propagation direction of GPs can be switched not only by changing the phase difference between dipoles, but also by placing the z-polarized dipole to its image position, whereas the handedness of the background field remains the same. The unidirectional excitation of GPs can be extended into arc graphene surface as well. Furthermore, our proposal on directional generation of GPs can be realized in a semiconductor nanowire/graphene system, where a semiconductor nanowire can mimic a circularly polarized dipole when illuminated by two orthogonally polarized plane waves. PMID:27557254

  6. Near field and exit wave computations for electron microscopy.

    PubMed

    Howie, A

    2013-11-01

    The partial wave phase shift formalism of atomic scattering is applied to compute exit wave functions for isolated Au and Si atoms under both plane wave and focused probe illumination. Connections between the far field and near field (exit) waves are clarified. This approach treats the Coulomb singularity properly though at 100 keV large numbers of phase shifts are required. In principle any form of incident wave can be handled so it may provide a means for testing traditional scattering theories used in electron microscopy. By applying the analysis to an atom embedded in a constant potential rather than free space, exit spheres of radius half the interatomic spacing can be used. PMID:23726769

  7. Study of Near Field Communication Technology in University Scenarios

    NASA Astrophysics Data System (ADS)

    Ruiz, Irene Luque; Miraz, Guillermo Matas; Gómez-Nieto, Miguel Ángel

    2009-08-01

    In this paper we present an introduction to the possibilities of NFC (Near Field Communication) technology in the University environment. NFC is the key for the development of interactive systems where "intelligent" objects interact with the user just only by touching the objects with a NFC device. We support that a University environment with active objects dispatching information and services to the users (students and teachers) can introduce an appropriate environment for the fulfillment of the new Educational European directives. Here, we briefly describe some of the possibilities of the NFC technology and we include an example of the use of NFC through a Smart Poster for a scenario where a Department directory is considered.

  8. Electromagnetic Near Field Measurements of Two Critical Assemblies

    NASA Astrophysics Data System (ADS)

    Goettee, Jeffrey; Goorley, Tim; Mayo, Douglas; Myers, William; Goda, Joetta; Sage, Frank

    2015-04-01

    Preliminary measurements of the fast metal nuclear reactors at the National Criticality Experiments Research Center (NCERC) and at White Sands Missile Range (WSMR) within the past year characterize the very near field environment of these critical assemblies. Both reactors are fast, highly enriched uranium metal reactors and can be operated in a burst mode above prompt supercritical. Initial measurements of the electric and the magnetic fields within the reactor cell are consistent between the two facilities, and begin to describe the dependance on distance and polarization as might be assumed from initial Monte Carlo modelling of these facilities. The amplitude and time variation of the electric and magnetic fields are consistent with burst time scales. The polarization is consistent with the geometry of the source and with Compton scattering from fission gammas as the dominant ionization mechanism. An overview of the two fast neutron sources and the excursion dynamics, the experimental details, and summary of the modelling calculations will be provided as background.

  9. Near field properties in relativistic heavy ion collisions

    NASA Astrophysics Data System (ADS)

    Li, Yang; Fries, Rainer; Kapusta, Joseph

    2006-04-01

    We study the properties of the soft gluon field produced in relativistic heavy ion collisions. In the spirit of McLerran-Venugopalan model, we write the field potential in a power series of the proper time τ and solve the Yang-Mills equation along with color current conservation equations simultaneously. We find that the classical gluon field at small τ, i.e., the near field, is mainly longitudinal. We also calculate the energy-momentum tensor of the field. This gluon field will decay and thermalize into a quark gluon plasma. Our results can be used as the initial conditions for the consequent relativistic hydrodynamic description of the dense parton matter.

  10. Near-field phase singularity in subwavelength metallic microstructures

    SciTech Connect

    Kang Ming; Guo Qinghua; Chen Jing; Gu Bing; Li Yongnan; Wang Huitian

    2011-10-15

    A near-field phase singularity (NFPS) depending on the spin state of the incident electromagnetic (EM) radiation is very fascinating because it can enrich the functionality of the EM radiation in metamaterials. Here we present a microscopic dipole model to describe the NFPS effect under the time-harmonic quasistatic limit. The results reveal that NFPS exists for the longitudinal components of both electric and magnetic fields as well as the transverse component of time-averaged Poynting vector. The localized surface plasmon polariton in the subwavelength metallic structure contributes to enhance the generation efficiency of NFPS by introducing the resonance of the electric dipole. This effect not only is promising for microtrapping and manipulation but also enriches the functionality of the existing metamaterials.

  11. Near-field photocurrent nanoscopy on bare and encapsulated graphene

    NASA Astrophysics Data System (ADS)

    Woessner, Achim; Alonso-González, Pablo; Lundeberg, Mark B.; Gao, Yuanda; Barrios-Vargas, Jose E.; Navickaite, Gabriele; Ma, Qiong; Janner, Davide; Watanabe, Kenji; Cummings, Aron W.; Taniguchi, Takashi; Pruneri, Valerio; Roche, Stephan; Jarillo-Herrero, Pablo; Hone, James; Hillenbrand, Rainer; Koppens, Frank H. L.

    2016-02-01

    Optoelectronic devices utilizing graphene have demonstrated unique capabilities and performances beyond state-of-the-art technologies. However, requirements in terms of device quality and uniformity are demanding. A major roadblock towards high-performance devices are nanoscale variations of the graphene device properties, impacting their macroscopic behaviour. Here we present and apply non-invasive optoelectronic nanoscopy to measure the optical and electronic properties of graphene devices locally. This is achieved by combining scanning near-field infrared nanoscopy with electrical read-out, allowing infrared photocurrent mapping at length scales of tens of nanometres. Using this technique, we study the impact of edges and grain boundaries on the spatial carrier density profiles and local thermoelectric properties. Moreover, we show that the technique can readily be applied to encapsulated graphene devices. We observe charge build-up near the edges and demonstrate a solution to this issue.

  12. Scanning near field microwave microscopy based on an active resonator

    NASA Astrophysics Data System (ADS)

    Qureshi, Naser; Kolokoltsev, Oleg; Ordonez-Romero, Cesar Leonardo

    2014-03-01

    A large number of recent implementations of near field scanning microwave microscopy (NFSMM) have been based on the perturbation of a resonant cavity connected to a sharp scanning probe. In this work we present results from an alternative approach: the perturbation of a microwave source connected to a scanning tip. Based on a yittrium iron garnet (YIG) cavity ring resonator this scanning probe system has a quality factor greater than 106, which allows us to detect very small frequency shifts, which translates to a very high sensitivity in sample impedance measurements. Using a selection of representative semiconductor, metal and biological samples we show how this approach leads to unusually high sensitivity and spatial resolution. Work supported by a grant from PAPIIT, UNAM 104513.

  13. Theoretical and experimental examination of near-field acoustic levitation.

    PubMed

    Nomura, Hideyuki; Kamakura, Tomoo; Matsuda, Kazuhisa

    2002-04-01

    A planar object can be levitated stably close to a piston sound source by making use of acoustic radiation pressure. This phenomenon is called near-field acoustic levitation [Y. Hashimoto et al., J. Acoust. Soc. Am. 100, 2057-2061 (1996)]. In the present article, the levitation distance is predicted theoretically by numerically solving basic equations in a compressible viscous fluid subject to the appropriate initial and boundary conditions. Additionally, experiments are carried out using a 19.5-kHz piston source with a 40-mm aperture and various aluminum disks of different sizes. The measured levitation distance agrees well with the theory, which is different from a conventional theory, and the levitation distance is not inversely proportional to the square root of the surface density of the levitated disk in a strict sense. PMID:12002842

  14. Detection of reflector surface from near field phase measurements

    NASA Technical Reports Server (NTRS)

    Ida, Nathan

    1991-01-01

    The deviation of a reflector antenna surface from a perfect parabolic shape causes degradation of the performance of the antenna. The problem of determining the shape of the reflector surface in a reflector antenna using near field phase measurements is not a new one. A recent issue of the IEEE tansactions on Antennas and Propagation (June 1988) contained numerous descriptions of the use of these measurements: holographic reconstruction or inverse Fourier transform. Holographic reconstruction makes use of measurement of the far field of the reflector and then applies the Fourier transform relationship between the far field and the current distribution on the reflector surface. Inverse Fourier transformation uses the phase measurements to determine the far field pattern using the method of Kerns. After the far field pattern is established, an inverse Fourier transform is used to determine the phases in a plane between the reflector surface and the plane in which the near field measurements were taken. These calculations are time consuming since they involve a relatively large number of operations. A much faster method can be used to determine the position of the reflector. This method makes use of simple geometric optics to determine the path length of the ray from the feed to the reflector and from the reflector to the measurement point. For small physical objects and low frequencies, diffraction effects have a major effect on the error, and the algorithm provides incorrect results. It is believed that the effect is less noticeable for large distortions such as antenna warping, and more noticeable for small, localized distortions such as bumps and depressions such as might be caused by impact damage.

  15. Solar terrestrial coupling through space plasma processes

    SciTech Connect

    Birn, J.

    2000-12-01

    This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The project investigates plasma processes that govern the interaction between the solar wind, charged particles ejected from the sun, and the earth's magnetosphere, the region above the ionosphere governed by the terrestrial magnetic field. Primary regions of interest are the regions where different plasma populations interact with each other. These are regions of particularly dynamic plasma behavior, associated with magnetic flux and energy transfer and dynamic energy release. The investigations concerned charged particle transport and energization, and microscopic and macroscopic instabilities in the magnetosphere and adjacent regions. The approaches combined space data analysis with theory and computer simulations.

  16. Near-field radiative heat transfer between arbitrarily shaped objects and a surface

    NASA Astrophysics Data System (ADS)

    Edalatpour, Sheila; Francoeur, Mathieu

    2016-07-01

    A fluctuational electrodynamics-based formalism for calculating near-field radiative heat transfer between objects of arbitrary size and shape and an infinite surface is presented. The surface interactions are treated analytically via Sommerfeld's theory of electric dipole radiation above an infinite plane. The volume integral equation for the electric field is discretized using the thermal discrete dipole approximation (T-DDA). The framework is verified against exact results in the sphere-surface configuration and is applied to analyze near-field radiative heat transfer between a complex-shaped probe and an infinite plane, both made of silica. It is found that, when the probe tip size is approximately equal to or smaller than the gap d separating the probe and the surface, coupled localized surface phonon (LSPh)-surface phonon-polariton (SPhP) mediated heat transfer occurs. In this regime, the net spectral heat rate exhibits four resonant modes due to LSPhs along the minor axis of the probe, while the net total heat rate in the near field follows a d-0.3 power law. Conversely, when the probe tip size is much larger than the separation gap d , heat transfer is mediated by SPhPs, resulting in two resonant modes in the net spectral heat rate, corresponding to those of a single emitting silica surface, while the net total heat rate approaches a d-2 power law. It is also demonstrated that a complex-shaped probe can be approximated by a prolate spheroidal electric dipole when the thermal wavelength is larger than the major axis of the spheroidal dipole and when the separation gap d is much larger than the radius of curvature of the dipole tip facing the surface.

  17. Dissociative identity disorder and the process of couple therapy.

    PubMed

    Macintosh, Heather B

    2013-01-01

    Couple therapy in the context of dissociative identity disorder (DID) has been neglected as an area of exploration and development in the couple therapy and trauma literature. What little discussion exists focuses primarily on couple therapy as an adjunct to individual therapy rather than as a primary treatment for couple distress and trauma. Couple therapy researchers have begun to develop adaptations to provide effective support to couples dealing with the impact of childhood trauma in their relationships, but little attention has been paid to the specific and complex needs of DID patients in couple therapy (H. B. MacIntosh & S. Johnson, 2008 ). This review and case presentation explores the case of "Lisa," a woman diagnosed with DID, and "Don," her partner, and illustrates the themes of learning to communicate, handling conflicting needs, responding to child alters, and addressing sexuality and education through their therapy process. It is the hope of the author that this discussion will renew interest in the field of couple therapy in the context of DID, with the eventual goal of developing an empirically testable model of treatment for couples. PMID:23282049

  18. High throughput optical lithography by scanning a massive array of bowtie aperture antennas at near-field

    NASA Astrophysics Data System (ADS)

    Wen, X.; Datta, A.; Traverso, L. M.; Pan, L.; Xu, X.; Moon, E. E.

    2015-11-01

    Optical lithography, the enabling process for defining features, has been widely used in semiconductor industry and many other nanotechnology applications. Advances of nanotechnology require developments of high-throughput optical lithography capabilities to overcome the optical diffraction limit and meet the ever-decreasing device dimensions. We report our recent experimental advancements to scale up diffraction unlimited optical lithography in a massive scale using the near field nanolithography capabilities of bowtie apertures. A record number of near-field optical elements, an array of 1,024 bowtie antenna apertures, are simultaneously employed to generate a large number of patterns by carefully controlling their working distances over the entire array using an optical gap metrology system. Our experimental results reiterated the ability of using massively-parallel near-field devices to achieve high-throughput optical nanolithography, which can be promising for many important nanotechnology applications such as computation, data storage, communication, and energy.

  19. High throughput optical lithography by scanning a massive array of bowtie aperture antennas at near-field

    PubMed Central

    Wen, X.; Datta, A.; Traverso, L. M.; Pan, L.; Xu, X.; Moon, E. E.

    2015-01-01

    Optical lithography, the enabling process for defining features, has been widely used in semiconductor industry and many other nanotechnology applications. Advances of nanotechnology require developments of high-throughput optical lithography capabilities to overcome the optical diffraction limit and meet the ever-decreasing device dimensions. We report our recent experimental advancements to scale up diffraction unlimited optical lithography in a massive scale using the near field nanolithography capabilities of bowtie apertures. A record number of near-field optical elements, an array of 1,024 bowtie antenna apertures, are simultaneously employed to generate a large number of patterns by carefully controlling their working distances over the entire array using an optical gap metrology system. Our experimental results reiterated the ability of using massively-parallel near-field devices to achieve high-throughput optical nanolithography, which can be promising for many important nanotechnology applications such as computation, data storage, communication, and energy. PMID:26525906

  20. Manipulating quantum dot fluorescence by utilizing Brownian induced near-field interactions with plasmonic nanoparticles

    NASA Astrophysics Data System (ADS)

    Palombo, Nola

    Quantum dots (QDs) are semiconductor nanocrystals with size-dependent optical properties; thus making them supreme fluorophores. Plasmonic nanoparticles (PNPs), such as gold and silver nanoparticles, support localized surface plasmons on their surface. When the localized surface plasmons are excited, a highly concentrated electromagnetic field is formed near the particle. Therefore, if a QD is within the near-field of a PNP, the emission or excitation of the QD can be enhanced. However, due to Forster Resonance Energy Transfer (FRET), the QD fluorescence could instead be quenched by the proximity of PNPs. Whether enhancement or quenching occurs, is dependent upon the distance and geometry of the nanoparticles. Enhanced QD fluorescence would be helpful in biomedical sensing and imaging and solar energy conversion applications. In addition, quenched QD fluorescence caused by FRET could be applied to FRET-based sensing and imaging in medical diagnosis. This master's thesis first theoretically models the stochastic movement of QDs and PNPs in an aqueous solution. The simulation is based upon the Direct Simulation Monte Carlo method coupled with Langevin equations. Using this simulation, we were able to predict the percentage of QDs in the near-field region of PNPs. The percentage of QDs in the near-field region of GNPs for a concentration of 1 × 1013 QDs/mL and 5 × 108 GNPs/mL, is a very small percentage of 2 × 10-5%. Yet, the concentration of QDs in the near-field region of GNPs was calculated to be 1,510,000 QDs mL-1. In addition, this master's thesis experimentally explores the enhancement and quenching of QD emission for different concentrations and sizes of PNPs in aqueous solutions. The fluorescence spectra of two types of QD-PNP mixtures were measured. The first mixture was QDs and gold nanoparticles (GNPs) dispersed in distilled water, where the emission wavelength of the QDs matches the localized surface plasmon excitation wavelength of the GNPs. The second

  1. Reciprocity theory of apertureless scanning near-field optical microscopy with point-dipole probes.

    PubMed

    Esslinger, Moritz; Vogelgesang, Ralf

    2012-09-25

    Near-field microscopy offers the opportunity to reveal optical contrast at deep subwavelength scales. In scanning near-field optical microscopy (SNOM), the diffraction limit is overcome by a nanoscopic probe in close proximity to the sample. The interaction of the probe with the sample fields necessarily perturbs the bare sample response, and a critical issue is the interpretation of recorded signals. For a few specific SNOM configurations, individual descriptions have been modeled, but a general and intuitive framework is still lacking. Here, we give an exact formulation of the measurable signals in SNOM which is easily applicable to experimental configurations. Our results are in close analogy with the description Tersoff and Hamann have derived for the tunneling currents in scanning tunneling microscopy. For point-like scattering probe tips, such as used in apertureless SNOM, the theory simplifies dramatically to a single scalar relation. We find that the measured signal is directly proportional to the field of the coupled tip-sample system at the position of the tip. For weakly interacting probes, the model thus verifies the empirical findings that the recorded signal is proportional to the unperturbed field of the bare sample. In the more general case, it provides guidance to an intuitive and faithful interpretation of recorded images, facilitating the characterization of tip-related distortions and the evaluation of novel SNOM configurations, both for aperture-based and apertureless SNOM. PMID:22897563

  2. Theoretical analysis of the microwave-drill near-field localized heating effect

    NASA Astrophysics Data System (ADS)

    Jerby, E.; Aktushev, O.; Dikhtyar, V.

    2005-02-01

    The microwave-drill principle [Jerby et al., Science 298, 587 (2002)] is based on a localized hot-spot effect induced by a near-field coaxial applicator. The microwave drill melts the nonmetallic material locally and penetrates mechanically into it to shape the hole. This paper presents a theoretical analysis of the thermal-runaway effect induced in front of the microwave drill. The model couples the Maxwell's and heat equations including the material's temperature-dependent properties. A finite-difference time-domain algorithm is applied in a two-time-scale numerical model. The simulation is demonstrated for mullite, and benchmarked in simplified cases. The results show a temperature rise of ˜103K/s up to 1300K within a hot spot confined to a ˜4-mm width (˜0.1 wavelength). The input-port response to this near-field effect is modeled by equivalent time-varying lumped-circuit elements. Besides the physical insight, this theoretical study provides computational tools for design and analysis of microwave drills and for their real-time monitoring and adaptive impedance matching.

  3. Analysis of biological tissues using scanning near-field infrared microspectroscopy

    NASA Astrophysics Data System (ADS)

    Jeung, Andrew G.; Erramilli, Shyamsunder; Hong, Mi K.; Huie, Phil; Smith, Todd I.

    1997-10-01

    Infrared absorption microspectroscopy is a useful technique to analyze biological tissues, as it can rapidly and non- destructively provide quantitative information about the molecular composition of tissue on a small spatial scale. At the Stanford Picosecond Free Electron Laser Center, a Scanning Near-field Infrared Microscope (SNIM) with the Free Electron Laser (FEL) as its illumination source has been used for in situ microspectroscopic characterization of constituents in human atherosclerotic tissue. The system consists of a Near-field Scanning Optical Microscope utilizing a tapered chalcogenide fiber as the scanning probe. The Stanford mid-infrared FEL provides high power infrared radiation that can be easily coupled into the chalcogenide fiber and whose wavelength is continuously tunable from 3 to 15 micrometers. With the FEL, the SNIM can acquire an image at a single wavelength of a 200 micrometer square region with 2 micrometer spatial resolution in under 30 minutes. It can also obtain infrared spectra at sub- wavelength resolution. The SNIM was used to examine unstained, frozen microtone sections of human atherosclerotic lesions. Spectra from localized regions in the sample were taken and analyzed to determine the distribution of various protein, lipid, and mineral constituents among the tissue microstructures. These findings were compared with results obtained by polarization microscopy and traditional histological staining techniques. The molecular information obtained in these studies can potentially lead to a greater understanding of atherosclerosis. Moreover, they demonstrate the usefulness of SNIM towards micrometer-scale vibrational microspectroscopy.

  4. Eliminating amplitude death by the asymmetry coupling and process delay in coupled oscillators

    NASA Astrophysics Data System (ADS)

    Yao, Chenggui; Zhao, Qi; Zou, Wei

    2016-02-01

    Coupling mode plays a key role in determining the dynamical behavior and realizing certain system's rhythm and function in the complex systems. In this work, the effects of the asymmetry and process delay in the coupling on the dynamical behavior are investigated. We find that both the asymmetry and process delay effectively reduce the region of the frequency-mismatch-induced amplitude death in the parameter space, and make the system to recover oscillation in the amplitude death regime so as to retain sustained system's rhythm function. Furthermore, we show the asymmetry and process delay can destroy synchronization. Our results suggest that the asymmetry coupling and process delay are of crucial importance in controlling amplitude death and synchronization, and hence that their considerations are vital for modeling real life problems.

  5. Near-field photochemical and radiation-induced chemical fabrication of nanopatterns of a self-assembled silane monolayer.

    PubMed

    Fischer, Ulrich Christian; Hentschel, Carsten; Fontein, Florian; Stegemann, Linda; Hoeppener, Christiane; Fuchs, Harald; Hoeppener, Stefanie

    2014-01-01

    A general concept for parallel near-field photochemical and radiation-induced chemical processes for the fabrication of nanopatterns of a self-assembled monolayer (SAM) of (3-aminopropyl)triethoxysilane (APTES) is explored with three different processes: 1) a near-field photochemical process by photochemical bleaching of a monomolecular layer of dye molecules chemically bound to an APTES SAM, 2) a chemical process induced by oxygen plasma etching as well as 3) a combined near-field UV-photochemical and ozone-induced chemical process, which is applied directly to an APTES SAM. All approaches employ a sandwich configuration of the surface-supported SAM, and a lithographic mask in form of gold nanostructures fabricated through colloidal sphere lithography (CL), which is either exposed to visible light, oxygen plasma or an UV-ozone atmosphere. The gold mask has the function to inhibit the photochemical reactions by highly localized near-field interactions between metal mask and SAM and to inhibit the radiation-induced chemical reactions by casting a highly localized shadow. The removal of the gold mask reveals the SAM nanopattern. PMID:25247126

  6. A Methodology for Near-Field Tsunami Inundation Forecasting

    NASA Astrophysics Data System (ADS)

    Gusman, A. R.; Tanioka, Y.

    2014-12-01

    Here we describe a new methodology for near-field tsunami inundation forecasting. We designed an algorithm that can produce high-resolution tsunami inundation maps of near-field sites before the actual tsunami hits the shore. This algorithm relies on a database of precomputed tsunami waveforms at several near-shore points and precomputed tsunami inundation maps from various earthquake fault model scenarios. By using numerical forward model, it takes several hours to simulate tsunami inundation in each site from each fault model. After information about a tsunami source is estimated, tsunami waveforms at near-shore points can be simulated in real-time. A scenario that gives the most similar tsunami waveforms is selected as the site-specific best scenario and the tsunami inundation from that scenario is selected as the tsunami inundation forecast. To test the algorithm, tsunami inundation along the Sanriku coast is forecasted by using source models for the 2011 Tohoku earthquake estimated from GPS, W phase, or offshore tsunami waveform data. The forecasting algorithm is capable of providing a tsunami inundation forecast that is similar to that obtained by numerical forward modeling, but with remarkably smaller CPU time. The time required to forecast tsunami inundation in 15 coastal sites from the Sendai Plain to Miyako City is approximately 3 minutes after information about the tsunami source is obtained. We found that the tsunami inundation forecasts from the 5-min GPS, 10-min W phase fault models, and 35-min tsunami source model are all reliable for tsunami early warning purposes and quantitatively match the observations well, although the latter model gives tsunami forecasts with highest overall accuracy. We evaluated the effectiveness of this algorithm in the real world by carrying out a tsunami evacuation drill in Kushiro City, Hokkaido, Japan, involving the city residents. The participants found that the use of the tsunami inundation forecast map produced by

  7. Direct measurement of source RDP`s and yields from near-field Soviet seismic data. Final report

    SciTech Connect

    Saikia, C.K.; McLaren, J.P.; Helmberger, D.V.

    1994-08-01

    The objective of this study was to investigate the source characteristics represented in the form of a reduced displacement potential (RDP) of Soviet nuclear explosions and was based on the availability of in-country near-field data. At the start of the project, it was thought that data would be readily accessible to us with the start of the open exchange of seismic data between the US and the Soviet Union. In fact, we did receive near-field waveforms of two Soviet nuclear explosions from Azghir test site near the Caspian Sea following which the transfer of data stopped till the end of the project. Consequently, the research effort was descoped. Only recently, some additional data have become available at CSS (Center for Seismic Studies). We have undertaken a thorough investigation of the limited data available from a large coupled shot (64 kT) in Azghir followed five years later by a decoupled shot (8 kT). We have successfully modeled the near-field data from these events to determine their source RDP`s and establish a decoupling factor of 15 using a time-domain waveform modeling technique. The results of this study are presented in the enclosed manuscript: Analysis of near-field data from a Soviet decoupling experiment.

  8. Nanomovement of azo polymers induced by metal tip enhanced near-field irradiation

    SciTech Connect

    Ishitobi, Hidekazu; Tanabe, Mamoru; Sekkat, Zouheir; Kawata, Satoshi

    2007-08-27

    Nanomovement of azo polymers induced by metal tip enhanced near-field illumination was studied. A protrusion with 47 nm full width at half maximum was induced with a resolution beyond the diffraction limit. At the top of the protrusion, an anisotropic movement occurs in a direction nearly parallel to the polarization of the incident light, and suggests the existence at the tip end of not only a longitudinal but also a lateral component of the electric field of light. The anisotropic photofluidity and the optical gradient force played important roles in the process of the light induced polymer movement.

  9. Near-field dynamics of ultrashort pulsed Bessel beams in media with Kerr nonlinearity.

    PubMed

    Polesana, P; Dubietis, A; Porras, M A; Kucinskas, E; Faccio, D; Couairon, A; Di Trapani, P

    2006-05-01

    The near-field dynamics of a femtosecond Bessel beam propagating in a Kerr nonlinear medium (fused silica) is investigated both numerically and experimentally. We demonstrate that the input Bessel beam experiences strong nonlinear reshaping. Due to the combined action of self-focusing and nonlinear losses the reshaped beam exhibits a radial compression and reduced visibility of the Bessel oscillations. Moreover, we show that the reshaping process starts from the intense central core and gradually replaces the Bessel beam profile during propagation, highlighting the conical geometry of the energy flow. PMID:16803062

  10. Near-field tsunami edge waves and complex earthquake rupture

    USGS Publications Warehouse

    Geist, Eric L.

    2013-01-01

    The effect of distributed coseismic slip on progressive, near-field edge waves is examined for continental shelf tsunamis. Detailed observations of edge waves are difficult to separate from the other tsunami phases that are observed on tide gauge records. In this study, analytic methods are used to compute tsunami edge waves distributed over a finite number of modes and for uniformly sloping bathymetry. Coseismic displacements from static elastic theory are introduced as initial conditions in calculating the evolution of progressive edge-waves. Both simple crack representations (constant stress drop) and stochastic slip models (heterogeneous stress drop) are tested on a fault with geometry similar to that of the M w = 8.8 2010 Chile earthquake. Crack-like ruptures that are beneath or that span the shoreline result in similar longshore patterns of maximum edge-wave amplitude. Ruptures located farther offshore result in reduced edge-wave excitation, consistent with previous studies. Introduction of stress-drop heterogeneity by way of stochastic slip models results in significantly more variability in longshore edge-wave patterns compared to crack-like ruptures for the same offshore source position. In some cases, regions of high slip that are spatially distinct will yield sub-events, in terms of tsunami generation. Constructive interference of both non-trapped and trapped waves can yield significantly larger tsunamis than those that produced by simple earthquake characterizations.

  11. Imaging Nanoscale Electromagnetic Near-Field Distributions Using Optical Forces.

    PubMed

    Huang, Fei; Tamma, Venkata Ananth; Mardy, Zahra; Burdett, Jonathan; Wickramasinghe, H Kumar

    2015-01-01

    We demonstrate the application of Atomic Force Microscopy (AFM) for mapping optical near-fields with nanometer resolution, limited only by the AFM probe geometry. By detecting the optical force between a gold coated AFM probe and its image dipole on a glass substrate, we profile the electric field distributions of tightly focused laser beams with different polarizations. The experimentally recorded focal force maps agree well with theoretical predictions based on a dipole-dipole interaction model. We experimentally estimate the aspect ratio of the apex of gold coated AFM probe using only optical forces. We also show that the optical force between a sharp gold coated AFM probe and a spherical gold nanoparticle of radius 15 nm, is indicative of the electric field distribution between the two interacting particles. Photo Induced Force Microscopy (PIFM) allows for background free, thermal noise limited mechanical imaging of optical phenomenon over wide range of wavelengths from Visible to RF with detection sensitivity limited only by AFM performance. PMID:26073331

  12. Investigation of the arcjet plume near field using electrostatic probes

    NASA Technical Reports Server (NTRS)

    Sankovic, John M.

    1990-01-01

    The near field plum of a 1 kW class arcjet thruster was investigated using electrostatic probes of various geometries. The electron number densities and temperatures were determined in a simulated hydrazine plume at axial distances between 3 cm (1.2 in) and 15 cm (5.9 in) and radial distances extending to 10 cm (3.9 in) off centerline. Values of electron number densities obtained using cylindrical and spherical probes of different geometries agreed very well. The electron density on centerline followed a source flow approximation for axial distances as near as 3 cm (1.2 in) from the nozzle exit plane. The model agreed well with previously obtained data in the far field. The effects of propellant mass flow rate and input power level were also studied. Cylindrical probes were used to obtain ion streamlines by changing the probe orientation with respect to the flow. The effects of electrical configuration on the plasma characteristics of the plume were also investigated by using a segmented anode/nozzle thruster. The results showed that the electrical configuration in the nozzle affected the distribution of electrons in the plume.

  13. Investigation of the Arcjet near Field Plume Using Electrostatic Probes

    NASA Technical Reports Server (NTRS)

    Sankovic, John M.

    1990-01-01

    The near field plume of a 1 kW class arcjet thruster was investigated using electrostatic probes of various geometries. The electron number densities and temperatures were determined in a simulated hydrazine plume at axial distances between 3 cm (1.2 in.) and 15 cm (5.9 in.) and radial distances extending to 10 cm (3.9 in.) off centerline. Values of electron number densities obtained using cylindrical and spherical probes of different geometries agreed very well. The electron density on centerline followed a source flow approximation for axial distances as near as 3 cm (1.2 in.) from the nozzle exit plane. The model agreed well with previously obtained data in the far field. The effects of propellant mass flow rate and input power level were also studied. Cylindrical probes were used to obtain ion streamlines by changing the probe orientation with respect to the flow. The effects of electrical configuration on the plasma characteristics of the plume were also investigated by using a segmented anode/nozzle thruster. The results showed that the electrical configuration in the nozzle affected the distribution of electrons in the plume.

  14. Radiation and near field in resistance-inductor circuit transients

    NASA Astrophysics Data System (ADS)

    Latypov, Damir; Bulmer, John

    2012-06-01

    A full wave solution to the classical problem of a transient response in an RL circuit is analyzed. We show that when radiation effects are rigorously taken into account, the response differs from a familiar exponential decay. The circuit behaves more like an RLC circuit and can exhibit an underdamped response. As a result of a two way energy transfer between the circuit and the near field in the underdamped regime, despite the radiation losses, current decay may be slower than predicted by the standard RL circuit model. During a transient, when retardation effects become important, inductance can no longer be defined as a coefficient of proportionality between the magnetic flux through the circuit and the current in the circuit. If rate of current decay is nearly constant, one can define a time-dependent generalized inductance which turns into conventional inductance after time D/c, where D is the diameter of the current loop. Connection of this generalized inductance with the radiation damping problem is discussed. The theory developed in this paper has been used to analyze ultra wide band radiation observed during a fast laser triggered superconducting to normal transition of a superconducting switch.

  15. Near-Field Acoustical Characterization of Clustered Rocket Engines

    NASA Technical Reports Server (NTRS)

    Kandula, Max; Vu, Bruce T.; Lindsay Halie K.

    2005-01-01

    This paper presents an approach for the prediction and characterization of the near-field acoustic levels from closely-spaced clustered rocket engines. The calculations are based on the method proposed by Eldred, wherein the flowfield from the clustered rockets is divided into two zones. Zone 1 contains the isolated nozzles which produce noise independently, and extends up to a distance where the individual flows completely mix to form an equivalent single nozzle flow. Zone 2 is occupied by the single mixed stream starting from the station where the jets merge. The acoustic fields from the two zones are computed separately on the basis of the NASA-SP method of Eldred developed for a single equivalent nozzle. A summation of the spectra for the two zones yields the total effective sound pressure level for the clustered engines. Under certain conditions of nozzle spacing and flow parameters, the combined sound pressure level spectrum for the clustered nozzles displays a double peak. Test cases are presented here to demonstrate the importance of hydrodynamic interactions responsible for the double peak in the sound spectrum in the case of clustered rocket nozzles, and the role of ground reflections in the case of non-interfering jets. A graphics interface (Rocket Acoustic Prediction Tool) has been developed to take into account the effects of clustered nozzles and ground reflections.

  16. Nanosensors: From near field to far field applications

    NASA Astrophysics Data System (ADS)

    Herrera, Gloria M.; Félix, Hilsamar; Fierro, Pedro M.; Balaguera, Marcia; Pacheco, Leonardo; Briano, Julio G.; Marquez, Francisco; Ríos, Carlos; Hernández-Rivera, Samuel P.

    2011-06-01

    The DoD Center for Chemical Sensors Development at the University of Puerto Rico-Mayagüez has worked in developing sensors for threat agents for over 8 years. Work has continued under the ALERT DHS Center of Excellence. The approaches for sensing have covered many types of threat chemicals and some types of biological simulants, including high energetic materials, homemade explosives, mixtures and formulations, chemical agents simulants, toxic industrial chemicals and spore forming microorganisms. Sensing in the far field has been based in vibrational spectroscopy: Raman and infrared. Near field detection has been mainly based on nanotechnology enabled sensing platforms for Surface Enhanced Raman Scattering. Initial use of colloidal suspensions of silver and gold nanospheres eventually evolved to metallic and metal oxide nanorods and to particle immobilization, including sample smearing on substrates and drop-on-demand thermal inkjet printing of nanoparticles. Chemical reduction of metal ions has been substituted by clean photonic physical reduction that leaves the nanoactive surface highly exposed and overcomes the physico-chemical problem of double electrical layers posed by colloidal suspensions of nanoparticles. New avenues have open wide research endeavors by using laser techniques to form nanoprisms and interference based metallic nano-images and micro-images. UV based metal reduction on top of metal oxides nanostructures promises to provide the selectivity and sensitivity expected for the last 30-40 years. Various applications and experimental setups will be discussed.

  17. Generalized method of eigenoscillations for near-field optical microscopy

    NASA Astrophysics Data System (ADS)

    Jiang, Bor-Yuan; Zhang, Lingfeng; Castro Neto, Antonio; Basov, Dimitri; Fogler, Michael

    2015-03-01

    Electromagnetic interaction between a sub-wavelength particle (the ``probe'') and a material surface (the ``sample'') is studied theoretically. The interaction is shown to be governed by a series of resonances (eigenoscillations), corresponding to surface polariton modes localized near the probe. The resonance parameters depend on the dielectric function and geometry of the probe, as well as the surface reflectivity of the material. Calculation of such resonances is carried out for several axisymmetric particle shapes (spherical, spheroidal, and pear-shaped). For spheroids an efficient numerical method is proposed, capable of handling cases of large or strongly momentum-dependent surface reflectivity. The method is applied to modeling near-field spectroscopy studies of various materials. For highly resonant materials such as aluminum oxide (by itself or covered with graphene) a rich structure of the simulated signal is found, including multi-peak spectra and nonmonotonic approach curves. These features have a strong dependence on physical parameters, e.g., the probe shape. For less resonant materials such as silicon oxide the dependence is weaker, and the spheroid model is generally applicable.

  18. The integrated project NF-PRO: recent advances in European research on the near-field system

    SciTech Connect

    Sneyers, Alain; Grambow, Bernd; Aranyossy, Jean-Francois; Johnson, Lawrence

    2007-07-01

    The Integrated Project NF-PRO (Sixth Framework Programme by the European Commission) investigates key-processes in the near-field of a geological repository for the disposal of high-level vitrified waste and spent fuel. The paper discusses the project scope and content and gives a summary overview of advances made by NF-PRO. (authors)

  19. The coupling of pathways and processes through shared components

    PubMed Central

    2011-01-01

    Background The coupling of pathways and processes through shared components is being increasingly recognised as a common theme which occurs in many cell signalling contexts, in which it plays highly non-trivial roles. Results In this paper we develop a basic modelling and systems framework in a general setting for understanding the coupling of processes and pathways through shared components. Our modelling framework starts with the interaction of two components with a common third component and includes production and degradation of all these components. We analyze the signal processing in our model to elucidate different aspects of the coupling. We show how different kinds of responses, including "ultrasensitive" and adaptive responses, may occur in this setting. We then build on the basic model structure and examine the effects of additional control regulation, switch-like signal processing, and spatial signalling. In the process, we identify a way in which allosteric regulation may contribute to signalling specificity, and how competitive effects may allow an enzyme to robustly coordinate and time the activation of parallel pathways. Conclusions We have developed and analyzed a common systems platform for examining the effects of coupling of processes through shared components. This can be the basis for subsequent expansion and understanding the many biologically observed variations on this common theme. PMID:21714894

  20. Nonlinear spectroscopy in the near-field: time resolved spectroscopy and subwavelength resolution non-invasive imaging

    NASA Astrophysics Data System (ADS)

    Namboodiri, Mahesh; Khan, Tahirzeb; Karki, Khadga; Kazemi, Mehdi Mohammad; Bom, Sidhant; Flachenecker, Günter; Namboodiri, Vinu; Materny, Arnulf

    2014-04-01

    The combination of near-field microscopy along with nonlinear optical spectroscopic techniques is presented here. The scanning near-field imaging technique can be integrated with nonlinear spectroscopic techniques to improve spatial and axial resolution of the images. Additionally, ultrafast dynamics can be probed down to nano-scale dimension. The review shows some examples for this combination, which resulted in an exciton map and vibrational contrast images with sub-wavelength resolution. Results of two-color femtosecond time-resolved pump-probe experiments using scanning near-field optical microscopy (SNOM) on thin films of the organic semiconductor 3,4,9,10 Perylenetetracarboxylic dianhydride (PTCDA) are presented. While nonlinear Raman techniques have been used to obtain highly resolved images in combination with near-field microscopy, the use of femtosecond laser pulses in electronic resonance still constitutes a big challenge. Here, we present our first results on coherent anti-Stokes Raman scattering (fs-CARS) with femtosecond laser pulses detected in the near-field using SNOM. We demonstrate that highly spatially resolved images can be obtained from poly(3-hexylthiophene) (P3HT) nano-structures where the fs-CARS process was in resonance with the P3HT absorption and with characteristic P3HT vibrational modes without destruction of the samples. Sub-diffraction limited lateral resolution is achieved. Especially the height resolution clearly surpasses that obtained with standard microCARS. These results will be the basis for future investigations of mode-selective dynamics in the near-field.

  1. Vectorial near-field imaging of a GaN based photonic crystal cavity

    SciTech Connect

    La China, F. Intonti, F.; Caselli, N.; Lotti, F.; Vinattieri, A.; Gurioli, M.; Vico Triviño, N.; Carlin, J.-F.; Butté, R.; Grandjean, N.

    2015-09-07

    We report a full optical deep sub-wavelength imaging of the vectorial components of the electric local density of states for the confined modes of a modified GaN L3 photonic crystal nanocavity. The mode mapping is obtained with a scanning near-field optical microscope operating in a resonant forward scattering configuration, allowing the vectorial characterization of optical passive samples. The optical modes of the investigated cavity emerge as Fano resonances and can be probed without the need of embedded light emitters or evanescent light coupling into the nanocavity. The experimental maps, independently measured in the two in-plane polarizations, turn out to be in excellent agreement with numerical predictions.

  2. A three-dimensional finite element model of near-field scanning microwave microscopy

    NASA Astrophysics Data System (ADS)

    Balusek, Curtis; Friedman, Barry; Luna, Darwin; Oetiker, Brian; Babajanyan, Arsen; Lee, Kiejin

    2012-10-01

    A three-dimensional finite element model of an experimental near-field scanning microwave microscope (NSMM) has been developed and compared to experiment on non conducting samples. The microwave reflection coefficient S11 is calculated as a function of frequency with no adjustable parameters. There is qualitative agreement with experiment in that the resonant frequency can show a sizable increase with sample dielectric constant; a result that is not obtained with a two-dimensional model. The most realistic model shows a semi-quantitative agreement with experiment. The effect of different sample thicknesses and varying tip sample distances is investigated numerically and shown to effect NSMM performance in a way consistent with experiment. Visualization of the electric field indicates that the field is primarily determined by the shape of the coupling hooks.

  3. Near field effects of millimeter-wave power transmission for medical applications

    NASA Astrophysics Data System (ADS)

    Yoon, Hargsoon; Song, Kyo D.; Lee, Kunik; Kim, Jaehwan; Choi, Sang H.

    2011-04-01

    An integration of micro devices system and wireless power transmission (WPT) technology offers a great potential to revolutionize current health care devices. The system integration of wireless power transmission devices with smart microsensors is crucial for replacing a power storage devices and miniaturizing wireless biomedical systems. Our research goal is to replace battery power supply with an implantable millimeter-wave rectenna. Recently, a hat system with a small millimeter-wave antenna which can feed millimeter-wave power to thin-film rectenna array embedding Schottky diodes was introduced for neural sensing and stimulation applications. In order to prove the design concept and investigate wireless power coupling efficiency under the system design, near-field wireless power transmission was studied in terms of wave frequency and distance. Also, in this paper, we will present the influence of biological objects to the wireless power transmission, simulating the experimental conditions of human objects for future medical applications.

  4. Efficient near-field energy transfer and relieved Casimir stiction between sub-wavelength gratings

    NASA Astrophysics Data System (ADS)

    Liu, Xianglei; Zhao, Bo; Zhang, Zhuomin

    2015-03-01

    The promising applications of near-field heat transfer in thermophotovoltaic devices, thermal imaging, thermal rectifiers, and local thermal management have motivated the search for nanostructures capable of supporting higher efficiency or greater heat flux than simple planar substances. In this work, efficient and delocalized radiative heat transfer between two aligned 1D sub-wavelength gratings is demonstrated based on the scattering theory using the rigorous coupled-wave analysis (RCWA). It is shown that the heat flux can be greatly enhanced and the accurate prediction may differ significantly from that of the geometry-based Derjaguin's proximity approximation (PA). The underlying mechanism is attributed to the excitation of hyperbolic modes that increase the energy transmission by supporting propagation of waves with large parallel wavevectors and. Besides efficient energy transport, the performance is robust, insensitive to the relative lateral shift. In addition, the Casimir stiction considering both quantum and thermal fluctuations is found to be relieved compared with bulks.

  5. 'Squeezing' near-field thermal emission for ultra-efficient high-power thermophotovoltaic conversion.

    PubMed

    Karalis, Aristeidis; Joannopoulos, J D

    2016-01-01

    We numerically demonstrate near-field planar ThermoPhotoVoltaic systems with very high efficiency and output power, at large vacuum gaps. Example performances include: at 1200 °K emitter temperature, output power density 2 W/cm(2) with ~47% efficiency at 300 nm vacuum gap; at 2100 °K, 24 W/cm(2) with ~57% efficiency at 200 nm gap; and, at 3000 °K, 115 W/cm(2) with ~61% efficiency at 140 nm gap. Key to this striking performance is a novel photonic design forcing the emitter and cell single modes to cros resonantly couple and impedance-match just above the semiconductor bandgap, creating there a 'squeezed' narrowband near-field emission spectrum. Specifically, we employ surface-plasmon-polariton thermal emitters and silver-backed semiconductor-thin-film photovoltaic cells. The emitter planar plasmonic nature allows for high-power and stable high-temperature operation. Our simulations include modeling of free-carrier absorption in both cell electrodes and temperature dependence of the emitter properties. At high temperatures, the efficiency enhancement via resonant mode cross-coupling and matching can be extended to even higher power, by appropriately patterning the silver back electrode to enforce also an absorber effective surface-plasmon-polariton mode. Our proposed designs can therefore lead the way for mass-producible and low-cost ThermoPhotoVoltaic micro-generators and solar cells. PMID:27363522

  6. Teleseismic and near-field analysis of the Nahanni earthquakes in the Northwest Territories, Canada

    USGS Publications Warehouse

    Choy, G.L.; Boatwright, J.

    1988-01-01

    The analysis of the Nahanni earthquakes of October 5, 1985 (Ms 6.6), and December 23, 1985 (Ms 6.9), will have important implications for the assessment of seismic hazards in intraplate environments. To maximize the information available to seismic engineers, broadband data recorded teleseismically are analyzed jointly with strong-motion data recorded in the near field. The time-domain analysis of teleseismic data yields the source mechanisms, depths, and complexities of rupture of each earthquake. Both earthquakes occurred as shallow thrusts with centroid depths (6 to 7km) and shallowly dipping fault planes that correspond well with the aftershock distributions obtained from a local survey run by the Canadian Geological Survey. The shallow nodal plane for the October 5 earthquake dips 30?? to the WSW, while the shallow nodal planes of the subevents for the December 23 earthquake dip an average of 23?? to the WSW. The October 5 earthquake has an impulsive initial rupture, followed by a weak subevent of longer duration but smaller moment release. The December 23 earthquake exhibits more complexity, being comprised of three subevents of similar size. The subevent delays derived from the teleseismic analysis are used to help interpret arrivals in records of ground velocity recorded in the near field of the December 23 earthquake. The rupture geometries inferred from the joint near- and far-field analysis suggest that the rupture processes were unusually complicated and that the 2g peak that occurs late in one of the near-field records could be a localized phenomenon. -from Authors

  7. Analyses of biological systems using scanning near-field infrared microscopy

    NASA Astrophysics Data System (ADS)

    Jeung, Andrew G.

    1998-12-01

    We report the construction of a Scanning Near-field Infrared Microscope (SNIM) and its successful operation towards infrared microspectroscopic analysis of biological tissue. Infrared microspectroscopy is a useful technique that can rapidly identify and localize the chemical constituents within biological tissues and cells on the basis of the vibrational spectroscopic signatures of their organic functional groups. Such analysis may be particularly useful if carried out using near-field optics so as to achieve subwavelength resolution unavailable to Fourier Transform InfraRed (FTIR) microscopy. We constructed SNIM by adapting a conventional scanning near-field microscope for use in the infrared. In particular, we employ infrared- transmitting chalcogenide fibers to serve as the fiber optic probes, and a free electron laser, a laser tunable in the mid-infrared wavelength range, is used as the illumination source. SNIM has acquired mid-infrared images of metal, semiconductor, and biological samples. We have demonstrated resolution down to 2.5 micrometers, and the device appears to be sensitive to differences in sample absorption of less than 0.1 OD. We used SNIM to examine unstained microtome sections of human atherosclerotic lesions, both by infrared imaging and by localized vibrational spectroscopy. In this way, we were able to identify and localize protein, lipid, and mineral components within the tissue. The studies of atherosclerotic tissue illustrate the usefulness of SNIM towards in situ vibrational microspectroscopic investigation of biological systems. In addition, SNIM has demonstrated the ability to perform infrared microscopic imaging in a liquid medium, and we have successfully used the device to take images of living cells in a liquid environment. We believe that SNIM provides a unique opportunity to study the cellular processes of living cells and bacteria by spectroscopic means.

  8. Near Field Communication-based telemonitoring with integrated ECG recordings

    PubMed Central

    Morak, J.; Kumpusch, H.; Hayn, D.; Leitner, M.; Scherr, D.; Fruhwald, F.M.; Schreier, G.

    2011-01-01

    Objectives Telemonitoring of vital signs is an established option in treatment of patients with chronic heart failure (CHF). In order to allow for early detection of atrial fibrillation (AF) which is highly prevalent in the CHF population telemonitoring programs should include electrocardiogram (ECG) signals. It was therefore the aim to extend our current home monitoring system based on mobile phones and Near Field Communication technology (NFC) to enable patients acquiring their ECG signals autonomously in an easy-to-use way. Methods We prototypically developed a sensing device for the concurrent acquisition of blood pressure and ECG signals. The design of the device equipped with NFC technology and Bluetooth allowed for intuitive interaction with a mobile phone based patient terminal. This ECG monitoring system was evaluated in the course of a clinical pilot trial to assess the system’s technical feasibility, usability and patient’s adherence to twice daily usage. Results 21 patients (4f, 54 ± 14 years) suffering from CHF were included in the study and were asked to transmit two ECG recordings per day via the telemonitoring system autonomously over a monitoring period of seven days. One patient dropped out from the study. 211 data sets were transmitted over a cumulative monitoring period of 140 days (overall adherence rate 82.2%). 55% and 8% of the transmitted ECG signals were sufficient for ventricular and atrial rhythm assessment, respectively. Conclusions Although ECG signal quality has to be improved for better AF detection the developed communication design of joining Bluetooth and NFC technology in our telemonitoring system allows for ambulatory ECG acquisition with high adherence rates and system usability in heart failure patients. PMID:23616890

  9. Turbulence Measurements in the Near Field of a Wingtip Vortex

    NASA Technical Reports Server (NTRS)

    Chow, Jim; Zilliac, Greg; Bradshaw, Peter

    1997-01-01

    The roll-up of a wingtip vortex, at Reynolds number based on chord of 4.6 million was studied with an emphasis on suction side and near wake measurements. The research was conducted in a 32 in. x 48 in. low-speed wind tunnel. The half-wing model had a semi-span of 36 in. a chord of 48 in. and a rounded tip. Seven-hole pressure probe measurements of the velocity field surrounding the wingtip showed that a large axial velocity of up to 1.77 U(sub infinity) developed in the vortex core. This level of axial velocity has not been previously measured. Triple-wire probes have been used to measure all components of the Reynolds stress tensor. It was determined from correlation measurements that meandering of the vortex was small and did not appreciably contribute to the turbulence measurements. The flow was found to be turbulent in the near-field (as high as 24 percent RMS w - velocity on the edge of the core) and the turbulence decayed quickly with streamwise distance because of the nearly solid body rotation of the vortex core mean flow. A streamwise variation of the location of peak levels of turbulence, relative to the core centerline, was also found. Close to the trailing edge of the wing, the peak shear stress levels were found at the edge of the vortex core, whereas in the most downstream wake planes they occurred at a radius roughly equal to one-third of the vortex core radius. The Reynolds shear stresses were not aligned with the mean strain rate, indicating that an isotropic-eddy-viscosity based prediction method cannot accurately model the turbulence in the cortex. In cylindrical coordinates, with the origin at the vortex centerline, the radial normal stress was found to be larger than the circumferential.

  10. Image formation properties and inverse imaging problem in aperture based scanning near field optical microscopy.

    PubMed

    Schmidt, S; Klein, A E; Paul, T; Gross, H; Diziain, S; Steinert, M; Assafrao, A C; Pertsch, T; Urbach, H P; Rockstuhl, C

    2016-02-22

    Aperture based scanning near field optical microscopes are important instruments to study light at the nanoscale and to understand the optical functionality of photonic nanostructures. In general, a detected image is affected by both the transverse electric and magnetic field components of light. The discrimination of the individual field components is challenging as these four field components are contained within two signals in the case of a polarization resolved measurement. Here, we develop a methodology to solve the inverse imaging problem and to retrieve the vectorial field components from polarization and phase resolved measurements. Our methodology relies on the discussion of the image formation process in aperture based scanning near field optical microscopes. On this basis, we are also able to explain how the relative contributions of the electric and magnetic field components within detected images depend on the chosen probe. We can therefore also describe the influence of geometrical and material parameters of individual probes within the image formation process. This allows probes to be designed that are primarily sensitive either to the electric or magnetic field components of light. PMID:26907063

  11. Reactive Transport and Coupled THM Processes in Engineering Barrier Systems (EBS)

    SciTech Connect

    Steefel, Carl; Rutqvist, Jonny; Tsang, Chin-Fu; Liu, Hui-Hai; Sonnenthal, Eric; Houseworth, Jim; Birkholzer, Jens

    2010-08-31

    Geological repositories for disposal of high-level nuclear wastes generally rely on a multi-barrier system to isolate radioactive wastes from the biosphere. The multi-barrier system typically consists of a natural barrier system, including repository host rock and its surrounding subsurface environment, and an engineering barrier system (EBS). EBS represents the man-made, engineered materials placed within a repository, including the waste form, waste canisters, buffer materials, backfill and seals (OECD, 2003). EBS plays a significant role in the containment and long-term retardation of radionuclide release. EBS is involved in complex thermal, hydrogeological, mechanical, chemical and biological processes, such as heat release due to radionuclide decay, multiphase flow (including gas release due to canister corrosion), swelling of buffer materials, radionuclide diffusive transport, waste dissolution and chemical reactions. All these processes are related to each other. An in-depth understanding of these coupled processes is critical for the performance assessment (PA) for EBS and the entire repository. Within the EBS group of Used Fuel Disposition (UFD) Campaign, LBNL is currently focused on (1) thermal-hydraulic-mechanical-chemical (THMC) processes in buffer materials (bentonite) and (2) diffusive transport in EBS associated with clay host rock, with a long-term goal to develop a full understanding of (and needed modeling capabilities to simulate) impacts of coupled processes on radionuclide transport in different components of EBS, as well as the interaction between near-field host rock (e.g., clay) and EBS and how they effect radionuclide release. This final report documents the progress that LBNL has made in its focus areas. Specifically, Section 2 summarizes progress on literature review for THMC processes and reactive-diffusive radionuclide transport in bentonite. The literature review provides a picture of the state-of-the-art of the relevant research areas

  12. Coupling and Hydrodynamic Limit for the Inclusion Process

    NASA Astrophysics Data System (ADS)

    Opoku, Alex; Redig, Frank

    2015-08-01

    We show propagation of local equilibrium for the symmetric inclusion process (SIP) after diffusive rescaling of space and time, as well as the local equilibrium property of the non-equilibrium steady state in the boundary driven SIP. The main tool is self-duality and a coupling between SIP particles and independent random walkers.

  13. Response of marine composites subjected to near field blast loading

    NASA Astrophysics Data System (ADS)

    LiVolsi, Frank

    Experimental studies were performed to understand the explosive response of composite panels when exposed to near-field explosive loading in different environments. The panel construction under consideration was an E-glass fiber-reinforced composite laminate infused with vinyl ester resin (Derakane 8084). The panel was layered bi-axially with plain-woven fiber orientations at 0° and 90°. Panel dimensions were approximately 203 mm x 203 mm x 1 mm (8 in x 8 in x 0.04 in). Experiments were carried out with the panel fully clamped in a holding fixture, which was in turn fastened inside a water tank. The fixture was fastened in such a way as to allow for explosive loading experiments in the following environments: water submersion with water backing, water submersion with air backing, and air immersion with air backing. Experiments were performed in room temperature conditions, and additional experiments in the submerged environments were also performed at high and low water temperatures of 40°C and 0°C, respectively. A stereo Digital Image Correlation (DIC) system was employed to capture the full-field dynamic behavior of the panel during the explosive event. Results indicated that the immersion environment contributes significantly to the blast response of the material and to the specimens' appreciable damage characteristics. The water submersion with air backing environment was found to encourage the greatest panel center point deflection and the most significant damage mechanisms around the boundary. The air immersion with air backing environment was found to encourage less center point deflection and exhibited significant impact damage from the explosive capsule. The water submersion with water backing environment encouraged the least panel deflection and minimal interlaminate damage around the panel boundary and center. Water temperature was found to influence the panel center point deflection, but not damage mechanisms. Maximum positive center point

  14. Near field scanning optical microscopy of polycrystalline semiconductors

    NASA Astrophysics Data System (ADS)

    Herndon, Mary Kay

    1999-09-01

    Photovoltaic devices are commonly used for space applications and remote terrestrial power requirements. Polycrystalline solar cell devices often have much lower efficiencies than their crystalline counterparts, but because they can be fabricated much more cheaply, they can still be cost-effective when compared to single crystal devices. The long term goal of this work is to provide information that will lead to higher quality devices with improved cost efficiency. In order to do this, a better understanding of the mechanisms that take place in these materials is needed. The goal of this thesis was to improve our understanding of these devices by adapting a novel characterization technique, Near Field Scanning Optical Microscopy (NSOM), to the study of polycrystalline films. Visible light NSOM is a relatively new technique that allows for optical characterization of materials with resolution beyond the far-field diffraction limit. By using NSOM to study the physical and electrical properties of polycrystalline solar cells, individual grains can be studied and more insight can be gained as to how various properties of the thin films affect the device efficiency. For this research, an NSOM was designed and built to be versatile enough to handle the sorts of samples and measurements required for studying a variety of photovoltaic devices. As a first step, the NSOM was used to characterize single crystal GaAs solar cell devices. Measurements of topography and NSOM-induced photocurrent were obtained simultaneously on cross sections of the material, allowing the p-n junction to be probed. Because the NSOM data could be compared to an expected result, this allowed verification of the new microscope's imaging capabilities and ensured accurate data interpretation. Effects of surface recombination were detected on the cleaved edges. The NSOM was used to characterize surface quality and study the effects of surface passivation treatments. Of the polycrystalline materials

  15. Mass transport analysis in the near field of geologic repository

    NASA Astrophysics Data System (ADS)

    Lim, Doo-Hyun

    A two-dimensional model for the groundwater flow and the contaminant transport has been developed. A water-saturated, deep geologic repository for high-level radioactive wastes (HLW) is considered. The region containing a waste canister, a backfill material around the canister, and the near-field rock (NFR) surrounding the backfill is considered. Discrete-Fracture Network (DFN) is generated in the NFR based on distribution functions of the fracture geometry parameters by random sampling. Flow-bearing fracture network is identified, and is transformed into an equivalent continuous porous medium in two different ways without calculating flow rates through individual fractures. The first transformation is applied locally, generating a heterogeneous porous medium. The second transformation is applied for the entire NFR, resulting in a homogeneous porous medium. While the heterogeneous porous medium is considered to represent characteristics of water flow in DFN better than the homogeneous porous medium, the homogeneous porous medium was often used in previous performance assessment studies for its simplicity. After these transformations, the spatial distribution of groundwater flow rate is calculated by a finite element method. The numerical results for the total discharge at the outer boundary of the homogenized NFR after the second transformation are benchmarked by analytical solutions with a relative difference smaller than 0.55%. The contaminant transport is simulated by a random-walk particle-tracking method, based on the obtained flow-rate distribution. Previous study for a step equation that determines the movement of contaminant particles has been critically reviewed. Numerical results obtained by the first and second transformations have been compared. The second transformation gives smaller mean values of the residence time of particles in the NFR and greater mean values of the mass absorption rate at the outer boundary of NFR than the first one does. Thus

  16. Simulation of Stochastic Processes by Coupled ODE-PDE

    NASA Technical Reports Server (NTRS)

    Zak, Michail

    2008-01-01

    A document discusses the emergence of randomness in solutions of coupled, fully deterministic ODE-PDE (ordinary differential equations-partial differential equations) due to failure of the Lipschitz condition as a new phenomenon. It is possible to exploit the special properties of ordinary differential equations (represented by an arbitrarily chosen, dynamical system) coupled with the corresponding Liouville equations (used to describe the evolution of initial uncertainties in terms of joint probability distribution) in order to simulate stochastic processes with the proscribed probability distributions. The important advantage of the proposed approach is that the simulation does not require a random-number generator.

  17. A novel ultrasonic clutch using near-field acoustic levitation.

    PubMed

    Chang, Kuo-Tsi

    2004-10-01

    This paper investigates design, fabrication and drive of an ultrasonic clutch with two transducers. For the two transducers, one serving as a driving element of the clutch is connected to a driving shaft via a coupling, and the other serving as a slave element of the clutch is connected to a slave shaft via another coupling. The principle of ultrasonic levitation is first expressed. Then, a series-resonant inverter is used to generate AC voltages at input terminals of each transducer, and a speed measuring system with optic sensors is used to find the relationship between rotational speed of the slave shaft and applied voltage of each transducer. Moreover, contact surfaces of the two transducers are coupled by the frictional force when both the two transducers are not energized, and separated using the ultrasonic levitation when at least one of the two transducers is energized at high voltages at resonance. PMID:15358528

  18. Optical far- and near-field femtosecond laser ablation of Si for nanoscale chemical analysis

    SciTech Connect

    Zormpa, Vasileia; Mao, Xianglei; Russo, Richard E.

    2010-02-02

    Extending spatial resolution in laser-based chemical analysis to the nanoscale becomes increasingly important as nanoscience and nanotechnology develop. Implementation of femtosecond laser pulses arises as a basic strategy for increasing resolution since it is associated with spatially localized material damage. In this work we study femtosecond laser far- and near-field processing of silicon (Si) at two distinct wavelengths (400 and 800 nm), for nanoscale chemical analysis. By tightly focusing femtosecond laser beams in the far-field we were able to produce sub-micrometer craters. In order to further reduce the crater size, similar experiments were performed in the near-field through sub-wavelength apertures, resulting to the formation of sub-30 nm craters. Laser Induced Breakdown Spectroscopy (LIBS) was used for chemical analysis with a goal to identify the minimum crater size from which spectral emission could be measured. Emission from sub-micrometer craters (full-with-at-half-maximum) was possible, which are among the smallest ever reported for femtosecond LIBS.

  19. Three-Dimensional Super-Resolution Morphology by Near-Field Assisted White-Light Interferometry

    PubMed Central

    Wang, Feifei; Liu, Lianqing; Yu, Peng; Liu, Zhu; Yu, Haibo; Wang, Yuechao; Li, Wen Jung

    2016-01-01

    Recent developments in far-field fluorescent microscopy have enabled nanoscale imaging of biological entities by ingenious applications of fluorescent probes. For non-fluorescence applications, however, scanning probe microscopy still remains one of the most commonly used methods to “image” nanoscale features in all three dimensions, despite its limited throughput and invasiveness to scanned samples. Here, we propose a time-efficient three-dimensional super-resolution microscopy method: near-field assisted white light interferometry (NFWLI). This method takes advantage of topography acquisition using white-light interferometry and lateral near-field imaging via a microsphere superlens. The ability to discern structures in central processing units (CPUs) with minimum feature sizes of approximately 50 nm in the lateral dimensions and approximately 10 nm in the axial dimension within 25 s (40 times faster than atomic force microscopes) was demonstrated. We elaborate in this paper the principles of NFWLI and demonstrate its potential for becoming a practical method for high-speed and non-toxic three-dimensional nanoscale imaging. PMID:27102207

  20. Near-field hazard assessment of March 11, 2011 Japan Tsunami sources inferred from different methods

    USGS Publications Warehouse

    Wei, Y.; Titov, V.V.; Newman, A.; Hayes, G.; Tang, L.; Chamberlin, C.

    2011-01-01

    Tsunami source is the origin of the subsequent transoceanic water waves, and thus the most critical component in modern tsunami forecast methodology. Although impractical to be quantified directly, a tsunami source can be estimated by different methods based on a variety of measurements provided by deep-ocean tsunameters, seismometers, GPS, and other advanced instruments, some in real time, some in post real-time. Here we assess these different sources of the devastating March 11, 2011 Japan tsunami by model-data comparison for generation, propagation and inundation in the near field of Japan. This study provides a comparative study to further understand the advantages and shortcomings of different methods that may be potentially used in real-time warning and forecast of tsunami hazards, especially in the near field. The model study also highlights the critical role of deep-ocean tsunami measurements for high-quality tsunami forecast, and its combination with land GPS measurements may lead to better understanding of both the earthquake mechanisms and tsunami generation process. ?? 2011 MTS.

  1. Three-Dimensional Super-Resolution Morphology by Near-Field Assisted White-Light Interferometry

    NASA Astrophysics Data System (ADS)

    Wang, Feifei; Liu, Lianqing; Yu, Peng; Liu, Zhu; Yu, Haibo; Wang, Yuechao; Li, Wen Jung

    2016-04-01

    Recent developments in far-field fluorescent microscopy have enabled nanoscale imaging of biological entities by ingenious applications of fluorescent probes. For non-fluorescence applications, however, scanning probe microscopy still remains one of the most commonly used methods to “image” nanoscale features in all three dimensions, despite its limited throughput and invasiveness to scanned samples. Here, we propose a time-efficient three-dimensional super-resolution microscopy method: near-field assisted white light interferometry (NFWLI). This method takes advantage of topography acquisition using white-light interferometry and lateral near-field imaging via a microsphere superlens. The ability to discern structures in central processing units (CPUs) with minimum feature sizes of approximately 50 nm in the lateral dimensions and approximately 10 nm in the axial dimension within 25 s (40 times faster than atomic force microscopes) was demonstrated. We elaborate in this paper the principles of NFWLI and demonstrate its potential for becoming a practical method for high-speed and non-toxic three-dimensional nanoscale imaging.

  2. Three-Dimensional Super-Resolution Morphology by Near-Field Assisted White-Light Interferometry.

    PubMed

    Wang, Feifei; Liu, Lianqing; Yu, Peng; Liu, Zhu; Yu, Haibo; Wang, Yuechao; Li, Wen Jung

    2016-01-01

    Recent developments in far-field fluorescent microscopy have enabled nanoscale imaging of biological entities by ingenious applications of fluorescent probes. For non-fluorescence applications, however, scanning probe microscopy still remains one of the most commonly used methods to "image" nanoscale features in all three dimensions, despite its limited throughput and invasiveness to scanned samples. Here, we propose a time-efficient three-dimensional super-resolution microscopy method: near-field assisted white light interferometry (NFWLI). This method takes advantage of topography acquisition using white-light interferometry and lateral near-field imaging via a microsphere superlens. The ability to discern structures in central processing units (CPUs) with minimum feature sizes of approximately 50 nm in the lateral dimensions and approximately 10 nm in the axial dimension within 25 s (40 times faster than atomic force microscopes) was demonstrated. We elaborate in this paper the principles of NFWLI and demonstrate its potential for becoming a practical method for high-speed and non-toxic three-dimensional nanoscale imaging. PMID:27102207

  3. The near-field transport code Tullgarn and its use in performance assessment

    SciTech Connect

    Sellin, P.; Kjellbert, N.

    1993-12-31

    The near-field radionuclide migration code Tullgarn has been developed for performance assessment purposes. As a part of the PROPER-code package it has been successfully applied in the SKB 91 safety analysis. THe features and processes included in the code are: (1) Radioactive chain decay; (2) Different canister failure mechanisms (copper corrosion from sulphide attack, steel corrosion, internal overpressure and initially defective canisters); (3) Spent fuel dissolution. The model is based on the assumption that the dissolution rate is proportional to the {alpha}-dose rate; (4) Transport calculations are done with a resistance-network model. Tullgarn calculates the stationary release of radionuclides from a defect in the canister through the buffer and out into a fracture in the rock or up to the damaged zone under the deposition tunnel. Tullgarn can be used as a stand-alone model for near-field release calculations or as a submodel in an integrated assessment. In the SKB 91 analysis, Tullgarn gave the source term to the far-field model.

  4. Numerical Investigation of Near-Field Plasma Flows in Magnetic Nozzles

    NASA Technical Reports Server (NTRS)

    Sankaran, Kamesh; Polzin, Kurt A.

    2009-01-01

    The development and application of a multidimensional numerical simulation code for investigating near-field plasma processes in magnetic nozzles are presented. The code calculates the time-dependent evolution of all three spatial components of both the magnetic field and velocity in a plasma flow, and includes physical models of relevant transport phenomena. It has been applied to an investigation of the behavior of plasma flows found in high-power thrusters, employing a realistic magnetic nozzle configuration. Simulation of a channel-flow case where the flow was super-Alfvenic has demonstrated that such a flow produces adequate back-emf to significantly alter the shape of the total magnetic field, preventing the flow from curving back to the magnetic field coil in the near-field region. Results from this simulation can be insightful in predicting far-field behavior and can be used as a set of self-consistent boundary conditions for far-field simulations. Future investigations will focus on cases where the inlet flow is sub-Alfvenic and where the flow is allowed to freely expand in the radial direction once it is downstream of the coil.

  5. Fiber-coupled THz spectroscopy for monitoring polymeric compounding processes

    NASA Astrophysics Data System (ADS)

    Vieweg, N.; Krumbholz, N.; Hasek, T.; Wilk, R.; Bartels, V.; Keseberg, C.; Pethukhov, V.; Mikulics, M.; Wetenkamp, L.; Koch, M.

    2007-06-01

    We present a compact, robust, and transportable fiber-coupled THz system for inline monitoring of polymeric compounding processes in an industrial environment. The system is built on a 90cm x 90cm large shock absorbing optical bench. A sealed metal box protects the system against dust and mechanical disturbances. A closed loop controller unit is used to ensure optimum coupling of the laser beam into the fiber. In order to build efficient and stable fiber-coupled antennas we glue the fibers directly onto photoconductive switches. Thus, the antenna performance is very stable and it is secured from dust or misalignment by vibrations. We discuss fabrication details and antenna performance. First spectroscopic data obtained with this system is presented.

  6. Gene regulation and noise reduction by coupling of stochastic processes

    PubMed Central

    Hornos, José Eduardo M.; Reinitz, John

    2015-01-01

    Here we characterize the low noise regime of a stochastic model for a negative self-regulating binary gene. The model has two stochastic variables, the protein number and the state of the gene. Each state of the gene behaves as a protein source governed by a Poisson process. The coupling between the the two gene states depends on protein number. This fact has a very important implication: there exist protein production regimes characterized by sub-Poissonian noise because of negative covariance between the two stochastic variables of the model. Hence the protein numbers obey a probability distribution that has a peak that is sharper than those of the two coupled Poisson processes that are combined to produce it. Biochemically, the noise reduction in protein number occurs when the switching of genetic state is more rapid than protein synthesis or degradation. We consider the chemical reaction rates necessary for Poisson and sub-Poisson processes in prokaryotes and eucaryotes. Our results suggest that the coupling of multiple stochastic processes in a negative covariance regime might be a widespread mechanism for noise reduction. PMID:25768447

  7. Gene regulation and noise reduction by coupling of stochastic processes

    NASA Astrophysics Data System (ADS)

    Ramos, Alexandre F.; Hornos, José Eduardo M.; Reinitz, John

    2015-02-01

    Here we characterize the low-noise regime of a stochastic model for a negative self-regulating binary gene. The model has two stochastic variables, the protein number and the state of the gene. Each state of the gene behaves as a protein source governed by a Poisson process. The coupling between the two gene states depends on protein number. This fact has a very important implication: There exist protein production regimes characterized by sub-Poissonian noise because of negative covariance between the two stochastic variables of the model. Hence the protein numbers obey a probability distribution that has a peak that is sharper than those of the two coupled Poisson processes that are combined to produce it. Biochemically, the noise reduction in protein number occurs when the switching of the genetic state is more rapid than protein synthesis or degradation. We consider the chemical reaction rates necessary for Poisson and sub-Poisson processes in prokaryotes and eucaryotes. Our results suggest that the coupling of multiple stochastic processes in a negative covariance regime might be a widespread mechanism for noise reduction.

  8. Near-field noise predictions of an aircraft in cruise

    NASA Technical Reports Server (NTRS)

    Rawls, John W., Jr.

    1987-01-01

    The physics of the coupling of sound waves with the boundary layer is not yet well understood. It is believed, however, that for effective coupling of the sound waves and instability waves in the boundary layer, a matching of both frequency and wave number must occur. This requires that the sound field be accurately defined in both space and time. Currently analytical prediction methods lack sufficient accuracy to predict the noise levels from components of a turbofan engine. Although empirical methods do not yield the detail required for an analysis of the receptivity of sound by a boundary layer, valuable insight can be gained as to the changes in noise levels that might be expected under various operating conditions and aircraft configurations.

  9. Near-field microwave scanning probe imaging of conductivity inhomogeneities in CVD graphene.

    PubMed

    Tselev, Alexander; Lavrik, Nickolay V; Vlassiouk, Ivan; Briggs, Dayrl P; Rutgers, Maarten; Proksch, Roger; Kalinin, Sergei V

    2012-09-28

    We have performed near-field scanning microwave microscopy (SMM) of graphene grown by chemical vapor deposition. Due to the use of probe-sample capacitive coupling and a relatively high ac frequency of a few GHz, this scanning probe method allows mapping of local conductivity without a dedicated counter electrode, with a spatial resolution of about 50 nm. Here, the coupling was enabled by atomic layer deposition of alumina on top of graphene, which in turn enabled imaging both large-area films, as well as micron-sized islands, with a dynamic range covering a low sheet resistance of a metal film and a high resistance of highly disordered graphene. The structures of graphene grown on Ni films and Cu foils are explored, and the effects of growth conditions are elucidated. We present a simple general scheme for interpretation of the contrast in the SMM images of our graphene samples and other two-dimensional conductors, which is supported by extensive numerical finite-element modeling. We further demonstrate that combination of the SMM and numerical modeling allows quantitative information about the sheet resistance of graphene to be obtained, paving the pathway for characterization of graphene conductivity with a sub-100 nm special resolution. PMID:22948033

  10. Plasmonic nanofocused four-wave mixing for femtosecond near-field imaging

    NASA Astrophysics Data System (ADS)

    Kravtsov, Vasily; Ulbricht, Ronald; Atkin, Joanna M.; Raschke, Markus B.

    2016-05-01

    Femtosecond nonlinear optical imaging with nanoscale spatial resolution would provide access to coupled degrees of freedom and ultrafast response functions on the characteristic length scales of electronic and vibrational excitations. Although near-field microscopy provides the desired spatial resolution, the design of a broadband high-contrast nanoprobe for ultrafast temporal resolution is challenging due to the inherently weak nonlinear optical signals generated in subwavelength volumes. Here, we demonstrate broadband four-wave mixing with enhanced nonlinear frequency conversion efficiency at the apex of a nanometre conical tip. Far-field light is coupled through a grating at the shaft of the tip, generating plasmons that propagate to the apex while undergoing asymptotic compression and amplification, resulting in a nonlinear conversion efficiency of up to 1 × 10–5. We apply this nonlinear nanoprobe to image the few-femtosecond coherent dynamics of plasmonic hotspots on a nanostructured gold surface with spatial resolution of a few tens of nanometres. The approach can be generalized towards spatiotemporal imaging and control of coherent dynamics on the nanoscale, including the extension to multidimensional spectroscopy and imaging.

  11. Near-field Microwave Scanning Probe Imaging of Conductivity Inhomogeneities in CVD Graphene

    SciTech Connect

    Tselev, Alexander; Lavrik, Nickolay V; Vlassiouk, Ivan V; Briggs, Dayrl P; Rutgers, Maarten; Proksch, Roger; Kalinin, Sergei V

    2012-01-01

    We have performed near-field scanning microwave microscopy (SMM) of graphene grown by chemical vapor deposition. Due to the use of probe-sample capacitive coupling and a relatively high ac frequency of a few GHz, this scanning probe method allows mapping of local conductivity without a dedicated counter electrode, with a spatial resolution of about 50 nm. Here, the coupling was enabled by atomic layer deposition of alumina on top of graphene, which in turn enabled imaging both large-area films, as well as micron-sized islands, with a dynamic range covering a low sheet resistance of a metal film and a high resistance of highly disordered graphene. The structures of graphene grown on Ni films and Cu foils are explored, and the effects of growth conditions are elucidated. We present a simple general scheme for interpretation of the contrast in the SMM images of our graphene samples and other two-dimensional conductors, which is supported by extensive numerical finite-element modeling. We further demonstrate that combination of the SMM and numerical modeling allows quantitative information about the sheet resistance of graphene to be obtained, paving the pathway for characterization of graphene conductivity with a sub-100 nm special resolution.

  12. Plasmonic nanofocused four-wave mixing for femtosecond near-field imaging.

    PubMed

    Kravtsov, Vasily; Ulbricht, Ronald; Atkin, Joanna M; Raschke, Markus B

    2016-05-01

    Femtosecond nonlinear optical imaging with nanoscale spatial resolution would provide access to coupled degrees of freedom and ultrafast response functions on the characteristic length scales of electronic and vibrational excitations. Although near-field microscopy provides the desired spatial resolution, the design of a broadband high-contrast nanoprobe for ultrafast temporal resolution is challenging due to the inherently weak nonlinear optical signals generated in subwavelength volumes. Here, we demonstrate broadband four-wave mixing with enhanced nonlinear frequency conversion efficiency at the apex of a nanometre conical tip. Far-field light is coupled through a grating at the shaft of the tip, generating plasmons that propagate to the apex while undergoing asymptotic compression and amplification, resulting in a nonlinear conversion efficiency of up to 1 × 10(-5). We apply this nonlinear nanoprobe to image the few-femtosecond coherent dynamics of plasmonic hotspots on a nanostructured gold surface with spatial resolution of a few tens of nanometres. The approach can be generalized towards spatiotemporal imaging and control of coherent dynamics on the nanoscale, including the extension to multidimensional spectroscopy and imaging. PMID:26854567

  13. Numerical simulation of the SAGD process coupled with geomechanical behavior

    NASA Astrophysics Data System (ADS)

    Li, Pingke

    Canada has vast oil sand resources. While a large portion of this resource can be recovered by surface mining techniques, a majority is located at depths requiring the application of in situ recovery technologies. Although a number of in situ recovery technologies exist, the steam assisted gravity drainage (SAGD) process has emerged as one of the most promising technologies to develop the in situ oil sands resources. During the SAGD operations, saturated steam is continuously injected into the oil sands reservoir, which induces pore pressure and stress variations. As a result, reservoir parameters and processes may also vary, particularly when tensile and shear failure occur. This geomechanical effect is obvious for oil sands material because oil sands have the in situ interlocked fabric. The conventional reservoir simulation generally does not take this coupled mechanism into consideration. Therefore, this research is to improve the reservoir simulation techniques of the SAGD process applied in the development of oil sands and heavy oil reservoirs. The analyses of the decoupled reservoir geomechanical simulation results show that the geomechanical behavior in SAGD has obvious impact on reservoir parameters, such as absolute permeability. The issues with the coupled reservoir geomechanical simulations of the SAGD process have been clarified and the permeability variations due to geomechanical behaviors in the SAGD process investigated. A methodology of sequentially coupled reservoir geomechanical simulation technique was developed based on the reservoir simulator, EXOTHERM, and the geomechanical simulator, FLAC. In addition, a representative geomechanical model of oil sands material was summarized in this research. Finally, this reservoir geomechanical simulation methodology was verified with the UTF Phase A SAGD project and applied in a SAGD operation with gas-over-bitumen geometry. Based on this methodology, the geomechanical effect on the SAGD production

  14. Method of processing materials using an inductively coupled plasma

    DOEpatents

    Hull, D.E.; Bieniewski, T.M.

    1987-04-13

    A method of processing materials. The invention enables ultrafine, ultrapure powders to be formed from solid ingots in a gas free environment. A plasma is formed directly from an ingot which insures purity. The vaporized material is expanded through a nozzle and the resultant powder settles on a cold surface. An inductively coupled plasma may also be used to process waste chemicals. Noxious chemicals are directed through a series of plasma tubes, breaking molecular bonds and resulting in relatively harmless atomic constituents. 3 figs.

  15. Evolution of Biomass Burning Aerosol Optical Properties in the Near Field

    NASA Astrophysics Data System (ADS)

    Sedlacek, A. J., III; Arnott, W. P.; Chand, D.; Fortner, E.; Freedman, A.; Kleinman, L. I.; Onasch, T. B.; Shilling, J. E.; Springston, S. R.

    2014-12-01

    Biomass burning (BB) events are known to produce chemically rich environments that can impact the evolution of primary aerosols and influence secondary aerosols production rates. With their increasing in frequency, BB events are expected to exert an ever-increasing impact on climate due to aerosol radiative forcing processes. One area that is still poorly understood is the evolution of these smoke aerosols in the near field. Recent literature suggests that BB aerosols undergo a rapid evolution near their source that is then followed by a slower aging phase. During the summer of 2013, the Department of Energy-sponsored an aircraft field campaign called the Biomass Burning Observation Project (BBOP) that specifically targeted the evolution of smoke aerosols in the near field (< 2 hours). Results examining the evolution of BB optical and microphysical properties will be presented. To probe these properties, the BBOP field campaign deployed a Single Particle Soot Photometer (SP2) to probe the mixing state of refractory black carbon (rBC) and a Soot Particle Aerosol Mass Spectrometer (SP-AMS) to investigate the composition of both non-refractory and rBC-containing particles. Aerosol optical properties were measured in situ using a 355 nm Photoacoustic spectrometer (PAS), a 532 nm photo thermal interferometer (PTI), a 630 nm cavity Attenuation Phase Shifted (CAPS) spectrometer, a 3-λ nephelometer, and a 3-λ PSAP. The BBOP study represented the maiden aircraft deployment for the SP-AMS, the 355 nm PAS and 532 nm PTI. Discussion will be on the near-field evolution of particle mixing state and morphology, chemical composition, and microphysical processes that determine aerosol size distributions and single scattering albedo (SSA) of light absorbing aerosols. In the cases studied, increases in the coating thickness of refractive black carbon (rBC) particles, organic aerosol/rBC ratio, scattering/CO ratio, and aerosol size distributions have been observed. Results will be

  16. Nanofocusing beyond the near-field diffraction limit via plasmonic Fano resonance

    NASA Astrophysics Data System (ADS)

    Song, Maowen; Wang, Changtao; Zhao, Zeyu; Pu, Mingbo; Liu, Ling; Zhang, Wei; Yu, Honglin; Luo, Xiangang

    2016-01-01

    paper, we propose a periodically repeated ring-disk complementary structure to break the near-field diffraction limit via plasmonic Fano resonance, originating from the interference between the complex hybrid plasmon resonance and the continuum of propagating waves through the silver film. This plasmonic Fano resonance introduces a π phase jump in the adjacent channels and amplitude modulation to achieve radiationless electromagnetic interference. As a result, deep subwavelength spots as small as 0.0045λ2 at 36 nm above the silver film have been numerically demonstrated. This plate holds promise for nanolithography, subdiffraction imaging and microscopy. Electronic supplementary information (ESI) available: The plasmon hybridization modes have been analyzed. The transmittance, reflectance and absorbance have been plotted to have a better understanding of the coupling in a silver nanoring. The dependencies of the intensity enhancement on the total numbers of building blocks have been shown. See DOI: 10.1039/c5nr06504f

  17. Modeling of the near-field distribution of pollutants coming from a coastal outfall

    NASA Astrophysics Data System (ADS)

    Lyubimova, T. P.; Roux, B.; Luo, S.; Parshakova, Y. N.; Shumilova, N. S.

    2013-04-01

    The present study concerns the 3-D distribution of pollutants emitted from a coastal outfall in the presence of strong sea currents. The problem is solved using the nonlinear Reynolds-averaged Navier-Stokes equations in the framework of the k-ɛ model. The constants of the logarithmic law for the vertical velocity profile in the bottom boundary layer are obtained by processing experimental data from acoustic Doppler current profilers (ADCPs). The near-field distribution of pollutants at different distances from the diffuser is obtained in terms of the ambient flow velocity (steady or with tidal effect) and outfall discharge characteristics. It is shown that even in the case where the effluent density is substantially lower than the ambient sea water density the plume can impact the seabed, creating a risk of pollution of removable bottom sediments.

  18. On the horizontal wobbling of an object levitated by near-field acoustic levitation.

    PubMed

    Kim, Cheol-Ho; Ih, Jeong-Guon

    2007-11-01

    A circular planar object can be levitated with several hundreds of microns by ultrasonic near-field acoustic levitation (NFAL). However, when both the sound source and the levitated object are circularly shaped and the center of the levitated object does not coincide with the source center, instability problem often occurs. When this happens, it becomes difficult to pick up or transport the object for the next process. In this study, when the center of the levitated object was offset from the source center, the moving direction of the levitated object was predicted by using the time averaged potential around the levitated object. The wobbling frequency of the levitated object was calculated by analyzing the nonlinear wobbling motion of the object. It was shown that the predicted wobbling frequencies agreed with measured ones well. Finally, a safe zone was suggested to avoid the unstable movement of an object. PMID:17590402

  19. Characterization of Coupled Hydrologic-Biogeochemical Processes Using Geophysical Data

    SciTech Connect

    Hubbard, Susan

    2005-06-01

    Biogeochemical and hydrological processes are naturally coupled and variable over a wide range of spatial and temporal scales. Many remediation approaches also induce dynamic transformations in natural systems, such as the generation of gases, precipitates and biofilms. These dynamic transformations are often coupled and can reduce the hydraulic conductivity of the geologic materials, making it difficult to introduce amendments or to perform targeted remediation. Because it is difficult to predict these transformations, our ability to develop effective and sustainable remediation conditions at contaminated sites is often limited. Further complicating the problem is the inability to collect the necessary measurements at a high enough spatial resolution yet over a large enough volume for understanding field-scale transformations.

  20. Calcium dynamics in astrocyte processes during neurovascular coupling

    PubMed Central

    Otsu, Yo; Couchman, Kiri; Lyons, Declan G; Collot, Mayeul; Agarwal, Amit; Mallet, Jean-Maurice; Pfrieger, Frank W; Bergles, Dwight E; Charpak, Serge

    2015-01-01

    Enhanced neuronal activity in the brain triggers a local increase in blood flow, termed functional hyperemia, via several mechanisms, including calcium (Ca2+) signaling in astrocytes. However, recent in vivo studies have questioned the role of astrocytes in functional hyperemia because of the slow and sparse dynamics of their somatic Ca2+ signals and the absence of glutamate metabotropic receptor 5 in adults. Here, we reexamined their role in neurovascular coupling by selectively expressing a genetically encoded Ca2+ sensor in astrocytes of the olfactory bulb. We show that in anesthetized mice, the physiological activation of olfactory sensory neuron (OSN) terminals reliably triggers Ca2+ increases in astrocyte processes but not in somata. These Ca2+ increases systematically precede the onset of functional hyperemia by 1–2 s, reestablishing astrocytes as potential regulators of neurovascular coupling. PMID:25531572

  1. A STIMULUS PARADIGM FOR ANALYSIS OF NEAR-FIELD HYDRODYNAMIC SENSITIVITY IN CRUSTACEANS

    PubMed

    Wilkens; Douglass

    1994-04-01

    We present several relatively simple procedures for studying the physiology of near-field mechanoreceptors in crustaceans which extend previous measures of sensitivity. The advantages include the quantitative analysis of range fractionation and directionality of receptors and interneurons in the sensory hierarchy of the central nervous system (CNS), based on a stimulus paradigm that is reproducible and easy to use. The technical considerations for quantitative fluid-coupled stimulation addressed by this paper are the complexity of dipole flow fields, reflected interference from traveling waves, and the underlying stimulus wave form. The techniques described here offer corresponding advantages for physiological experiments using other aquatic organisms. In electrophysiological experiments, crustacean preparations are typically placed in an experimental chamber filled with water or saline solution. For studies on near-field sensory receptors, i.e. those responding to flow fields in the aquatic medium, a dipole or vibrating sphere is frequently used to generate stimulus waves (Tautz et al. 1981; Wiese and Wollnik, 1983; Ebina and Wiese, 1984; Hatt, 1986; Heinisch and Wiese, 1987; Tautz, 1987; Wiese and Marschall, 1990; Killian and Page, 1992b). A dipole stimulator is easily constructed by attaching a spherical probe to an electromechanical device such as a loudspeaker, pen motor or piezo crystal. A periodic signal fed to the transducer generates the oscillating dipole movements. With the sphere immersed in the bathing medium, dipole flow fields are generated (see Kalmijn, 1988, for further discussion of dipole sources), whereas dipole oscillations introduced at the air­saline interface generate traveling surface waves. Numerous additional devices and techniques have been used to stimulate crustacean receptors. Several involve wave motion introduced from one end of the chamber by diaphragms or paddles (Laverack, 1962b, 1963; Flood and Wilkens, 1978), by cylindrical

  2. Strong near field enhancement in THz nano-antenna arrays

    PubMed Central

    Feuillet-Palma, Cheryl; Todorov, Yanko; Vasanelli, Angela; Sirtori, Carlo

    2013-01-01

    A key issue in modern photonics is the ability to concentrate light into very small volumes, thus enhancing its interaction with quantum objects of sizes much smaller than the wavelength. In the microwave domain, for many years this task has been successfully performed by antennas, built from metals that can be considered almost perfect at these frequencies. Antenna-like concepts have been recently extended into the THz and up to the visible, however metal losses increase and limit their performances. In this work we experimentally study the light coupling properties of dense arrays of subwavelength THz antenna microcavities. We demonstrate that the combination of array layout with subwavelength electromagnetic confinement allows for 104-fold enhancement of the electromagnetic energy density inside the cavities, despite the low quality factor of a single element. This effect is quantitatively described by an analytical model that can be applied for the optimization of any nanoantenna array. PMID:23449101

  3. Strong near field enhancement in THz nano-antenna arrays.

    PubMed

    Feuillet-Palma, Cheryl; Todorov, Yanko; Vasanelli, Angela; Sirtori, Carlo

    2013-01-01

    A key issue in modern photonics is the ability to concentrate light into very small volumes, thus enhancing its interaction with quantum objects of sizes much smaller than the wavelength. In the microwave domain, for many years this task has been successfully performed by antennas, built from metals that can be considered almost perfect at these frequencies. Antenna-like concepts have been recently extended into the THz and up to the visible, however metal losses increase and limit their performances. In this work we experimentally study the light coupling properties of dense arrays of subwavelength THz antenna microcavities. We demonstrate that the combination of array layout with subwavelength electromagnetic confinement allows for 10(4)-fold enhancement of the electromagnetic energy density inside the cavities, despite the low quality factor of a single element. This effect is quantitatively described by an analytical model that can be applied for the optimization of any nanoantenna array. PMID:23449101

  4. Tiled-grating compressor with uncompensated dispersion for near-field-intensity smoothing.

    PubMed

    Huang, H; Kessler, Terrance

    2007-07-01

    A tiled-grating compressor, in which the spatial dispersion is not completely compensated, reduces the near-field-intensity modulation caused by tiling gaps and provides near-field spatial filtering of the input laser beam, thus reducing the laser damage to the final optics. PMID:17603592

  5. Coupled Biogeochemical Process Evaluation for Conceptualizing Trichloroethylene Co-Metabolism

    SciTech Connect

    Rick Colwell; Corey Radtke; Mark Delwiche; Deborah Newby; Lynn Petzke; Mark Conrad; Eoin Brodie; Hope Lee; Bob Starr; Dana Dettmers; Ron Crawford; Andrzej Paszczynski; Nick Bernardini; Ravi Paidisetti; Tonia Green

    2006-06-01

    Chlorinated solvent wastes (e.g., trichloroethene or TCE) often occur as diffuse subsurface plumes in complex geological environments where coupled processes must be understood in order to implement remediation strategies. Monitored natural attenuation (MNA) warrants study as a remediation technology because it minimizes worker and environment exposure to the wastes and because it costs less than other technologies. However, to be accepted MNA requires different ?lines of evidence? indicating that the wastes are effectively destroyed. We are studying the coupled biogeochemical processes that dictate the rate of TCE co-metabolism first in the medial zone (TCE concentration: 1,000 to 20,000 ?g/L) of a plume at the Idaho National Laboratory?s Test Area North (TAN) site and then at Paducah or the Savannah River Site. We will use flow-through in situ reactors (FTISR) to investigate the rate of methanotrophic co-metabolism of TCE and the coupling of the responsible biological processes with the dissolved methane flux and groundwater flow velocity. TCE co-metabolic rates at TAN are being assessed and interpreted in the context of enzyme activity, gene expression, and cellular inactivation related to intermediates of TCE co-metabolism. By determining the rate of TCE co-metabolism at different groundwater flow velocities, we will derive key modeling parameters for the computational simulations that describe the attenuation, and thereby refine such models while assessing the contribution of microbial co-metabolism relative to other natural attenuation processes. This research will strengthen our ability to forecast the viability of MNA at DOE and other sites contaminated with chlorinated hydrocarbons.

  6. Coupled Biogeochemical Process Evaluation for Conceptualizing Trichloroethylene Co-Metabolism

    SciTech Connect

    Colwell, Frederick; Radtke, Corey; Newby, Deborah; Delwiche, Mark; Crawf, Ronald L.; Paszczynski, Andrzej; Strap, Janice; Conrad, Mark; Brodic, Eoin; Starr, Robert; Lee, Hope

    2006-04-05

    Chlorinated solvent wastes (e.g., trichloroethene or TCE) often occur as diffuse subsurface plumes in complex geological environments where coupled processes must be understood in order to implement remediation strategies. Monitored natural attenuation (MNA) warrants study as a remediation technology because it minimizes worker and environment exposure to the wastes and because it costs less than other technologies. However, to be accepted MNA requires 'lines of evidence' indicating that the wastes are effectively destroyed. Our research will study the coupled biogeochemical processes that dictate the rate of TCE co-metabolism in contaminated aquifers first at the Idaho National Laboratory and then at Paducah or the Savannah River Site, where natural attenuation of TCE is occurring. We will use flow-through in situ reactors to investigate the rate of methanotrophic co-metabolism of TCE and the coupling of the responsible biological processes with the dissolved methane flux and groundwater flow velocity. We will use new approaches (e.g., stable isotope probing, enzyme activity probes, real-time reverse transcriptase polymerase chain reaction, proteomics) to assay the TCE co-metabolic rates, and interpret these rates in the context of enzyme activity, gene expression, and cellular inactivation related to intermediates of TCE co-metabolism. By determining the rate of TCE co-metabolism at different methane concentrations and groundwater flow velocities, we will derive key modeling parameters for the computational simulations that describe the attenuation, and thereby refine such models while assessing the contribution of microbial relative to other natural attenuation processes. This research will strengthen our ability to forecast the viability of MNA at DOE and other sites that are contaminated with chlorinated hydrocarbons.

  7. Results From an International Simulation Study on Couples Thermal, Hydrological, and Mechanical (THM) Processes Near Geological Nuclear Waste Repositories

    SciTech Connect

    J. Rutqvist; D. Barr; J.T. Birkholzer; M. Chijimatsu; O. Kolditz; Q. Liu; Y. Oda; W. Wang; C. Zhang

    2006-08-02

    As part of the ongoing international DECOVALEX project, four research teams used five different models to simulate coupled thermal, hydrological, and mechanical (THM) processes near waste emplacement drifts of geological nuclear waste repositories. The simulations were conducted for two generic repository types, one with open and the other with back-filled repository drifts, under higher and lower postclosure temperatures, respectively. In the completed first model inception phase of the project, a good agreement was achieved between the research teams in calculating THM responses for both repository types, although some disagreement in hydrological responses is currently being resolved. In particular, good agreement in the basic thermal-mechanical responses was achieved for both repository types, even though some teams used relatively simplified thermal-elastic heat-conduction models that neglected complex near-field thermal-hydrological processes. The good agreement between the complex and simplified process models indicates that the basic thermal-mechanical responses can be predicted with a relatively high confidence level.

  8. Near field to far field transformations and multiple beam forming and steering

    NASA Technical Reports Server (NTRS)

    1984-01-01

    The feasibility of acoustic verification of microwave near field to far field transformation algorithms using the Phased Array Sonic Simulation System was studied. Existing electromagnetic near field measurement techniques and transformation algorithms (equations) were investigated. It was analytically determined that acoustic verification is valid. Acoustic simulation of electromagnetic near field to far field transformations is emphasized. The acoustic simulation of electromagnetic near field to far field transformation is verified for the modal expansion method. In the modal expansion method, data from antenna near field measurements are converted to a summation or spectrum of modes corresponding to wave numbers in the measurement coordinate system. Fourier transformation of those measurements preserves the far field information in a spectral form that is then readily extractable.

  9. Modeling Coupled Processes in Clay Formations for Radioactive Waste Disposal

    SciTech Connect

    Liu, Hui-Hai; Rutqvist, Jonny; Zheng, Liange; Sonnenthal, Eric; Houseworth, Jim; Birkholzer, Jens

    2010-08-31

    As a result of the termination of the Yucca Mountain Project, the United States Department of Energy (DOE) has started to explore various alternative avenues for the disposition of used nuclear fuel and nuclear waste. The overall scope of the investigation includes temporary storage, transportation issues, permanent disposal, various nuclear fuel types, processing alternatives, and resulting waste streams. Although geologic disposal is not the only alternative, it is still the leading candidate for permanent disposal. The realm of geologic disposal also offers a range of geologic environments that may be considered, among those clay shale formations. Figure 1-1 presents the distribution of clay/shale formations within the USA. Clay rock/shale has been considered as potential host rock for geological disposal of high-level nuclear waste throughout the world, because of its low permeability, low diffusion coefficient, high retention capacity for radionuclides, and capability to self-seal fractures induced by tunnel excavation. For example, Callovo-Oxfordian argillites at the Bure site, France (Fouche et al., 2004), Toarcian argillites at the Tournemire site, France (Patriarche et al., 2004), Opalinus clay at the Mont Terri site, Switzerland (Meier et al., 2000), and Boom clay at Mol site, Belgium (Barnichon et al., 2005) have all been under intensive scientific investigations (at both field and laboratory scales) for understanding a variety of rock properties and their relations with flow and transport processes associated with geological disposal of nuclear waste. Clay/shale formations may be generally classified as indurated and plastic clays (Tsang et al., 2005). The latter (including Boom clay) is a softer material without high cohesion; its deformation is dominantly plastic. For both clay rocks, coupled thermal, hydrological, mechanical and chemical (THMC) processes are expected to have a significant impact on the long-term safety of a clay repository. For

  10. Range-gated imaging for near-field target identification

    SciTech Connect

    Yates, G.J.; Gallegos, R.A.; McDonald, T.E.

    1996-12-01

    The combination of two complementary technologies developed independently at Los Alamos National Laboratory (LANL) and Sandia National Laboratory (SNL) has demonstrated feasibility of target detection and image capture in a highly light-scattering, medium. The technique uses a compact SNL developed Photoconductive Semiconductor Switch/Laser Diode Array (PCSS/LDA) for short-range (distances of 8 to 10 m) large Field-Of-View (FOV) target illumination. Generation of a time-correlated echo signal is accomplished using a photodiode. The return image signal is recorded with a high-speed shuttered Micro-Channel-Plate Image Intensifier (MCPII), declined by LANL and manufactured by Philips Photonics. The MCPII is rated using a high-frequency impedance-matching microstrip design to produce 150 to 200 ps duration optical exposures. The ultra first shuttering producer depth resolution of a few inches along the optic axis between the MCPII and the target, producing enhanced target images effectively deconvolved from noise components from the scattering medium in the FOV. The images from the MCPII are recorded with an RS-170 Charge-Coupled-Device camera and a Big Sky, Beam Code, PC-based digitizer frame grabber and analysis package. Laser pulse data were obtained by the but jitter problems and spectral mismatches between diode spectral emission wavelength and MCPII photocathode spectral sensitivity prevented the capture of fast gating imaging with this demonstration system. Continued development of the system is underway.

  11. Upscalling processes in an ocean-atmosphere multiscale coupled model

    NASA Astrophysics Data System (ADS)

    Masson, S. G.; Berthet, S.; Samson, G.; Crétat, J.; Colas, F.; Echevin, V.; Jullien, S.; Hourdin, C.

    2015-12-01

    This work explores new pathways toward a better representation of the multi-scale physics that drive climate variability. We are analysing the key upscaling processes by which small-scale localized errors have a knock-on effect onto global climate. We focus on the Peru-Chilli coastal upwelling, an area known to hold among the strongest models biases in the Tropics. Our approach is based on the development of a multiscale coupling interface allowing us to couple WRF with the NEMO oceanic model in a configuration including 2-way nested zooms in the oceanic and/or the atmospheric component of the coupled model. Upscalling processes are evidenced and quantified by comparing three 20-year long simulations of a tropical channel (45°S-45°N), which differ by their horizontal resolution: 0.75° everywhere, 0.75°+0.25° zoom in the southeastern Pacific or 0.25° everywhere. This set of three 20-year long simulations was repeated with 3 different sets of parameterizations to assess the robustness of our results. Our results show that adding an embedded zoom over the southeastern Pacific only in the atmosphere cools down the SST along the Peru-Chili coast, which is a clear improvement. This change is associated with a displacement of the low-level cloud cover, which moves closer to the coast cooling further the coastal area SST. Offshore, we observe the opposite effect with a reduction of the cloud cover with higher resolution, which increases solar radiation and warms the SST. Increasing the resolution in the oceanic component show contrasting results according to the different set parameterization used in the experiments. Some experiment shows a coastal cooling as expected, whereas, in other cases, we observe a counterintuitive response with a warming of the coastal SST. Using at the same time an oceanic and an atmospheric zoom mostly combines the results obtained when using the 2-way nesting in only one component of the coupled model. In the best case, we archive by this

  12. Narrow-band near-field nanoscopy in the spectral range from 1.3 to 8.5 THz

    NASA Astrophysics Data System (ADS)

    Kuschewski, F.; von Ribbeck, H.-G.; Döring, J.; Winnerl, S.; Eng, L. M.; Kehr, S. C.

    2016-03-01

    Nano-spectroscopy in the terahertz frequency range remains challenging despite recent technological progress in developing both THz emitter sources and near-field optical microscopy (SNOM). Here, we combine scattering-type SNOM with a free-electron laser light source, to tune into the 1.3-8.5 THz range. A significant portion of this range, namely, the frequencies above ˜3 THz, is not covered by previously reported near-field microscopy systems. However, it constitutes an indispensable regime where many elementary processes in solids including collective lattice excitations, charge, and spin transport occur. Our approach of nano-spectroscopy and nano-imaging provides a versatile analysis of nanostructures as small as 50 nm, hence beating the optical diffraction limit by λ/4600.

  13. Determination of the far-field from measured near-field data, theory and measuring technique of the near-field far-field transformation

    NASA Astrophysics Data System (ADS)

    Schrott, A.; Stein, V.

    1980-12-01

    Methods are described for measuring the far field of antennas at distances that are small compared to the wavelength of the field. The so called compact test range is explained and the principle of the near field far field transformation is described. The advantages and disadvantages of the planar, cylindrical, and spherical transformation techniques are discussed. Theory and measuring technique for the spherical method are treated extensively. An assessment of the influence of errors is given and the acceptable tolerances are presented. A proposal is given for the construction of a near field test range. Finally the performance of the method is demonstrated with the aid of some examples.

  14. The simulation of far-field wavelets using frequency-domain air-gun array near-field wavelets

    NASA Astrophysics Data System (ADS)

    Song, Jian-Guo; Deng, Yong; Tong, Xin-Xin

    2013-12-01

    Air-gun arrays are used in marine-seismic exploration. Far-field wavelets in subsurface media represent the stacking of single air-gun ideal wavelets. We derived single air-gun ideal wavelets using near-field wavelets recorded from near-field geophones and then synthesized them into far-field wavelets. This is critical for processing wavelets in marineseismic exploration. For this purpose, several algorithms are currently used to decompose and synthesize wavelets in the time domain. If the traveltime of single air-gun wavelets is not an integral multiple of the sampling interval, the complex and error-prone resampling of the seismic signals using the time-domain method is necessary. Based on the relation between the frequency-domain phase and the time-domain time delay, we propose a method that first transforms the real near-field wavelet to the frequency domain via Fourier transforms; then, it decomposes it and composes the wavelet spectrum in the frequency domain, and then back transforms it to the time domain. Thus, the resampling problem is avoided and single air-gun wavelets and far-field wavelets can be reliably derived. The effect of ghost reflections is also considered, while decomposing the wavelet and removing the ghost reflections. Modeling and real data processing were used to demonstrate the feasibility of the proposed method.

  15. Tilt effects on moment tensor inversion in the near field of active volcanoes

    NASA Astrophysics Data System (ADS)

    van Driel, M.; Wassermann, J.; Pelties, C.; Schiemenz, A.; Igel, H.

    2015-09-01

    Dynamic tilts (rotational motion around horizontal axes) change the projection of local gravity onto the horizontal components of seismometers. This causes sensitivity of these components to tilt, especially at low frequencies. We analyse the consequences of this effect onto moment tensor inversion for very long period (vlp) events in the near field of active volcanoes on the basis of synthetic examples using the station distribution of a real deployed seismic network and the topography of Mt. Merapi volcano (Java, Indonesia). The examples show that for periods in the vlp range of 10-30 s tilt can have a strong effect on the moment tensor inversion, although its effect on the horizontal seismograms is significant only for few stations. We show that tilts can be accurately computed using the spectral element method and include them in the Green's functions. The (simulated) tilts might be largely influenced by strain-tilt coupling (stc). However, due to the frequency dependence of the tilt contribution to the horizontal seismograms, only the largest tilt signals affect the source inversion in the vlp frequency range. As these are less sensitive to stc than the weaker signals, the effect of stc can likely be neglected in this application. In the converse argument, this is not necessarily true for longer periods, where the horizontal seismograms are dominated by the tilt signal and rotational sensors would be necessary to account for it. As these are not yet commercially available, this study underlines the necessity for the development of such instruments.

  16. Indirect interband transition induced by optical near fields with large wave numbers

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Maiku; Nobusada, Katsuyuki

    2016-05-01

    Optical near fields (ONFs) have Fourier components with large wave numbers that are two or three orders of magnitude larger than those of far-field propagating light owing to their nonuniformity in space. By utilizing these large wave numbers, the ONF is expected to induce an indirect interband transition between Bloch states having different wave numbers and directly generate an electron-hole pair without electron-phonon coupling. We perform time-dependent dynamics calculations of a one-dimensional periodic potential with an indirect band-gap structure and demonstrate that the ONF definitely induces an indirect interband transition. Instead of using the general Bloch boundary condition, which is usually imposed in conventional band structure calculations, we adopt an alternative boundary condition, the Born-von Kármán boundary condition, to appropriately treat indirect interband transitions. The calculated absorption spectra for the far-field and ONF excitations show different absorption edges and spectral patterns. We argue that this difference can be experimentally measured as evidence of the effects of the large wave numbers of the ONF.

  17. Photoconductive terahertz near-field detector with a hybrid nanoantenna array cavity

    SciTech Connect

    Mitrofanov, Oleg; Brener, Igal; Luk, Ting S.; Reno, John L.

    2015-11-19

    Nanoscale structuring of optical materials leads to modification of their properties and can be used for improving efficiencies of photonic devices and for enabling new functionalities. In ultrafast optoelectronic switches for generation and detection of terahertz (THz) radiation, incorporation of nanostructures allows us to overcome inherent limitations of photoconductive materials. We propose and demonstrate a nanostructured photoconductive THz detector for sampling highly localized THz fields, down to the level of λ/150. The nanostructure that consists of an array of optical nanoantennas and a distributed Bragg reflector forms a hybrid cavity, which traps optical gate pulses within the photoconductive layer. The effect of photon trapping is observed as enhanced absorption at a designed wavelength. This optically thin photoconductive THz detector allows us to detect highly confined evanescent THz fields coupled through a deeply subwavelength aperture as small as 2 μm (λ/150 at 1 THz). As a result, by monolithically integrating the THz detector with apertures ranging from 2 to 5 μm we realize higher spatial resolution and higher sensitivity in aperture-type THz near-field microscopy and THz time-domain spectroscopy.

  18. Photoconductive terahertz near-field detector with a hybrid nanoantenna array cavity

    DOE PAGESBeta

    Mitrofanov, Oleg; Brener, Igal; Luk, Ting S.; Reno, John L.

    2015-11-19

    Nanoscale structuring of optical materials leads to modification of their properties and can be used for improving efficiencies of photonic devices and for enabling new functionalities. In ultrafast optoelectronic switches for generation and detection of terahertz (THz) radiation, incorporation of nanostructures allows us to overcome inherent limitations of photoconductive materials. We propose and demonstrate a nanostructured photoconductive THz detector for sampling highly localized THz fields, down to the level of λ/150. The nanostructure that consists of an array of optical nanoantennas and a distributed Bragg reflector forms a hybrid cavity, which traps optical gate pulses within the photoconductive layer. Themore » effect of photon trapping is observed as enhanced absorption at a designed wavelength. This optically thin photoconductive THz detector allows us to detect highly confined evanescent THz fields coupled through a deeply subwavelength aperture as small as 2 μm (λ/150 at 1 THz). As a result, by monolithically integrating the THz detector with apertures ranging from 2 to 5 μm we realize higher spatial resolution and higher sensitivity in aperture-type THz near-field microscopy and THz time-domain spectroscopy.« less

  19. Optical forces on a Rayleigh dielectric particle in a patterned near-field landscape

    NASA Astrophysics Data System (ADS)

    Zelenina, Anna; Quidant, Romain; Petrov, Dmitri; Badenes, Goncal

    2005-07-01

    The trapping of micro-objects by optical radiation forces, so-called optical tweezers, has become widely used in physical, chemical and biological experiments where accurate and non-invasive manipulation is required. Recent advances in beam shaping render it possible for instance to rotate or to dynamically manipulate independently several elements. Today, one of the remaining challenges of conventional optical tweezers is the direct manipulation of systems with sizes belonging to the sub-wavelength or Rayleigh regime. Indeed, the diffraction limit prevents in that case from achieving a commensurable trapping volume and thus does not allow for minimizing the fluctuations in position of the trapped object due to its strong Brownian motion. In order to overcome this limitation, it has been proposed to use evanescent fields instead of the usual propagating fields. Recent advances in optics of noble metal nano-structures have recently provided new configurations to achieve nano-optical tweezers. Especially, tightly localized modes resulting from the coupling between resonant noble metal nanostructures may offer the gradient forces able to trap and manipulate Rayleigh objects. In this work, we calculate the radiation forces exerted on a nanometric dielectric sphere when exposed to a patterned optical near-field landscape at an interface decorated with resonant gold nanostructures. By comparing their magnitude with other forces that affect the movement of the particle, we discuss the practical ability of our configuration for multiple parallel optical manipulation.

  20. Queueing up for enzymatic processing: correlated signaling through coupled degradation.

    PubMed

    Cookson, Natalie A; Mather, William H; Danino, Tal; Mondragón-Palomino, Octavio; Williams, Ruth J; Tsimring, Lev S; Hasty, Jeff

    2011-01-01

    High-throughput technologies have led to the generation of complex wiring diagrams as a post-sequencing paradigm for depicting the interactions between vast and diverse cellular species. While these diagrams are useful for analyzing biological systems on a large scale, a detailed understanding of the molecular mechanisms that underlie the observed network connections is critical for the further development of systems and synthetic biology. Here, we use queueing theory to investigate how 'waiting lines' can lead to correlations between protein 'customers' that are coupled solely through a downstream set of enzymatic 'servers'. Using the E. coli ClpXP degradation machine as a model processing system, we observe significant cross-talk between two networks that are indirectly coupled through a common set of processors. We further illustrate the implications of enzymatic queueing using a synthetic biology application, in which two independent synthetic networks demonstrate synchronized behavior when common ClpXP machinery is overburdened. Our results demonstrate that such post-translational processes can lead to dynamic connections in cellular networks and may provide a mechanistic understanding of existing but currently inexplicable links. PMID:22186735

  1. A Fully Coupled Computational Model of the Silylation Process

    SciTech Connect

    G. H. Evans; R. S. Larson; V. C. Prantil; W. S. Winters

    1999-02-01

    This report documents the development of a new finite element model of the positive tone silylation process. Model development makes use of pre-existing Sandia technology used to describe coupled thermal-mechanical behavior in deforming metals. Material properties and constitutive models were obtained from the literature. The model is two-dimensional and transient and focuses on the part of the lithography process in which crosslinked and uncrosslinked resist is exposed to a gaseous silylation agent. The model accounts for the combined effects of mass transport (diffusion of silylation agent and reaction product), chemical reaction resulting in the uptake of silicon and material swelling, the generation of stresses, and the resulting material motion. The influence of stress on diffusion and reaction rates is also included.

  2. Evaluation of Near Field Atmospheric Dispersion Around Nuclear Facilities Using a Lorentzian Distribution Methodology

    SciTech Connect

    Hawkley, Gavin

    2014-01-01

    Atmospheric dispersion modeling within the near field of a nuclear facility typically applies a building wake correction to the Gaussian plume model, whereby a point source is modeled as a plane source. The plane source results in greater near field dilution and reduces the far field effluent concentration. However, the correction does not account for the concentration profile within the near field. Receptors of interest, such as the maximally exposed individual, may exist within the near field and thus the realm of building wake effects. Furthermore, release parameters and displacement characteristics may be unknown, particularly during upset conditions. Therefore, emphasis is placed upon the need to analyze and estimate an enveloping concentration profile within the near field of a release. This investigation included the analysis of 64 air samples collected over 128 wk. Variables of importance were then derived from the measurement data, and a methodology was developed that allowed for the estimation of Lorentzian-based dispersion coefficients along the lateral axis of the near field recirculation cavity; the development of recirculation cavity boundaries; and conservative evaluation of the associated concentration profile. The results evaluated the effectiveness of the Lorentzian distribution methodology for estimating near field releases and emphasized the need to place air-monitoring stations appropriately for complete concentration characterization. Additionally, the importance of the sampling period and operational conditions were discussed to balance operational feedback and the reporting of public dose.

  3. Near-field radiative thermal control with graphene covered on different materials

    NASA Astrophysics Data System (ADS)

    Wang, Ao; Zheng, Zhiheng; Xuan, Yimin

    2016-09-01

    Based on the structure of double-layer parallel plates, this paper demonstrates that thermal radiation in near field is greatly enhanced due to near-field effects, exceeding Planck‧s blackbody radiation law. To study the effect of graphene on thermal radiation in near field, the authors add graphene layer into the structure and analyze the ability of graphene to control near-field thermal radiation with different materials. The result indicates that the graphene layer effectively suppresses the near-field thermal radiation between metal plates or polar-dielectric plates, having good ability of thermal insulation. But for doped-silicon plates, depending on the specific models, graphene has different control abilities, suppressing or enhancing, and the control abilities mainly depend on the material graphene is attached to. The authors also summarize some common rules about the different abilities of graphene to control the near-field thermal radiation. In consideration of the thickness of 0.34 nm of monolayer graphene, this paper points out that graphene plays a very important role in controlling the near-field thermal radiation.

  4. Upscaled modeling of CO2 injection with coupled thermal processes

    NASA Astrophysics Data System (ADS)

    Gasda, Sarah; Stephansen, Annette; Dahle, Helge; Aavatsmark, Ivar

    2013-04-01

    Large-scale models of CO2 storage in geological formations must capture the relevant physical, chemical and thermodynamical processes that affect the migration and ultimate fate of injected CO2. These processes should be modeled over the appropriate length and time scales. Some important mechanisms include convection-driven dissolution, caprock roughness, and local capillary effects, all of which can impact the direction and speed of the plume as well as long-term trapping efficiency. In addition, CO2 can be injected at a different temperature than reservoir conditions, leading to significant density variation within the plume over space and time. This impacts buoyancy and migration patterns, which becomes particularly important for injection sites with temperature and pressure conditions near the critical point. Therefore, coupling thermal processes with fluid flow should be considered in order to correctly capture plume migration and trapping within the reservoir. A practical modeling approach for CO2 storage over relatively large length and time scales is the vertical-equilibrium model, which solves partially integrated conservation equations for flow in two lateral dimensions. We couple heat transfer within the vertical equilibrium framework for fluid flow, focusing on the thermal processes that most impact the CO2 plume. We investigate a simplified representation of heat exchange between the plume and the reservoir that also includes transport of heat within the plume. In addition, we explore CO2 thermodynamic models for reliable prediction of density under different injection pressures, temperatures and composition. The model concept is demonstrated on simple systems and applied to a realistic storage aquifer.

  5. Near-field millimeter-wave imaging for weapons detection

    NASA Astrophysics Data System (ADS)

    Sheen, David M.; McMakin, Douglas L.; Collins, H. D.; Hall, Thomas E.

    1993-04-01

    Various millimeter-wave imaging systems capable of imaging through clothing for the detection of contraband metal, plastic, or ceramic weapons, have been developed at PNL. Two dimensional scanned holographic systems, developed at 35, 90, and 350 GHz, are used to obtain high resolution images of metal and plastic targets concealed by clothing. Coherent single-frequency amplitude and phase data, which is gathered over a two-dimensional scanned aperture, is reconstructed to the target plane using a holographic wavefront reconstruction technique. Practical weapon detection systems require high-speed scanning. To achieve this goal, a 35 GHz linear sequentially switched array has been built and integrated into a high speed linear scanner. This system poses special challenges on calibration/signal processing of the holographic system. Further, significant improvements in speed are required to achieve real time operation. Toward this goal, a wideband scanned system which allows for a two- dimensional image formation from a one-dimensional scanned (or array) system has been developed. Signal/image processing techniques developed and implemented for this technique are a variation on conventional synthetic aperture radar (SAR) techniques which eliminate far- field and narrow-bandwidth requirements. Performance of this technique is demonstrated with imaging results obtained from a Ka-band system.

  6. Near-field millimeter-wave imaging for weapon detection

    SciTech Connect

    Sheen, D.M.; McMakin, D.L.; Collins, H.D.; Hall, T.E.

    1992-11-01

    Various millimeter-wave imaging systems capable of imaging through clothing for the detection of contraband metal, plastic, or ceramic weapons, have been developed at PNL. Two dimensional scanned holographic systems, developed at 35, 90, and 350 GHz, are used to obtain high resolution images of metal and plastic targets concealed by clothing. Coherent single-frequency amplitude and phase data, which is gathered over a two-dimensional scanned aperture, is reconstructed to the target plane using a holographic wavefront reconstruction technique. Practical weapon detection systems require high-speed scanning. To achieve this goal, a 35 GHz linear sequentially switched array has been built and integrated into a high speed linear scanner. This system poses special challenges on calibration / signal processing of the holographic system. Further, significant improvements in speed are required to achieve real time operation. Toward this goal, a wideband scanned system which allows for a two-dimensional image formation from a one-dimensional scanned (or array) system has been developed . Signal / image processing techniques developed and implemented for this technique are a variation on conventional synthetic aperture radar (SAR) techniques which eliminate far-field and narrow bandwidth requirements. Performance of this technique is demonstrated with imaging results obtained from a K[sub a]-band system.

  7. Near-field millimeter-wave imaging for weapon detection

    SciTech Connect

    Sheen, D.M.; McMakin, D.L.; Collins, H.D.; Hall, T.E.

    1992-11-01

    Various millimeter-wave imaging systems capable of imaging through clothing for the detection of contraband metal, plastic, or ceramic weapons, have been developed at PNL. Two dimensional scanned holographic systems, developed at 35, 90, and 350 GHz, are used to obtain high resolution images of metal and plastic targets concealed by clothing. Coherent single-frequency amplitude and phase data, which is gathered over a two-dimensional scanned aperture, is reconstructed to the target plane using a holographic wavefront reconstruction technique. Practical weapon detection systems require high-speed scanning. To achieve this goal, a 35 GHz linear sequentially switched array has been built and integrated into a high speed linear scanner. This system poses special challenges on calibration / signal processing of the holographic system. Further, significant improvements in speed are required to achieve real time operation. Toward this goal, a wideband scanned system which allows for a two-dimensional image formation from a one-dimensional scanned (or array) system has been developed . Signal / image processing techniques developed and implemented for this technique are a variation on conventional synthetic aperture radar (SAR) techniques which eliminate far-field and narrow bandwidth requirements. Performance of this technique is demonstrated with imaging results obtained from a K{sub a}-band system.

  8. Drift-Scale Coupled Processes (DST and THC Seepage) Models

    SciTech Connect

    P. Dixon

    2004-04-05

    The purpose of this Model Report (REV02) is to document the unsaturated zone (UZ) models used to evaluate the potential effects of coupled thermal-hydrological-chemical (THC) processes on UZ flow and transport. This Model Report has been developed in accordance with the ''Technical Work Plan for: Performance Assessment Unsaturated Zone'' (Bechtel SAIC Company, LLC (BSC) 2002 [160819]). The technical work plan (TWP) describes planning information pertaining to the technical scope, content, and management of this Model Report in Section 1.12, Work Package AUZM08, ''Coupled Effects on Flow and Seepage''. The plan for validation of the models documented in this Model Report is given in Attachment I, Model Validation Plans, Section I-3-4, of the TWP. Except for variations in acceptance criteria (Section 4.2), there were no deviations from this TWP. This report was developed in accordance with AP-SIII.10Q, ''Models''. This Model Report documents the THC Seepage Model and the Drift Scale Test (DST) THC Model. The THC Seepage Model is a drift-scale process model for predicting the composition of gas and water that could enter waste emplacement drifts and the effects of mineral alteration on flow in rocks surrounding drifts. The DST THC model is a drift-scale process model relying on the same conceptual model and much of the same input data (i.e., physical, hydrological, thermodynamic, and kinetic) as the THC Seepage Model. The DST THC Model is the primary method for validating the THC Seepage Model. The DST THC Model compares predicted water and gas compositions, as well as mineral alteration patterns, with observed data from the DST. These models provide the framework to evaluate THC coupled processes at the drift scale, predict flow and transport behavior for specified thermal-loading conditions, and predict the evolution of mineral alteration and fluid chemistry around potential waste emplacement drifts. The DST THC Model is used solely for the validation of the THC

  9. Near-field induction heating of metallic nanoparticles due to infrared magnetic dipole contribution

    NASA Astrophysics Data System (ADS)

    Chapuis, Pierre-Olivier; Laroche, Marine; Volz, Sebastian; Greffet, Jean-Jacques

    2008-03-01

    We revisit the electromagnetic heat transfer between a metallic nanoparticle and a highly conductive metallic semi-infinite substrate, commonly studied using the electric dipole approximation. For infrared and microwave frequencies, we find that the magnetic polarizability of the particle is larger than the electric one. We also find that the local density of states in the near field is dominated by the magnetic contribution. As a consequence, the power absorbed by the particle in the near field is due to dissipation by fluctuating eddy currents. These results show that a number of near-field effects involving metallic particles should be affected by the fluctuating magnetic fields.

  10. Fluorescence near-field microscopy of DNA at sub-10 nm resolution.

    PubMed

    Ma, Ziyang; Gerton, Jordan M; Wade, Lawrence A; Quake, Stephen R

    2006-12-31

    We demonstrate apertureless near-field microscopy of single molecules at sub-10 nm resolution. With a novel phase filter, near-field images of single organic fluorophores were obtained with approximately sixfold improvement in the signal-to-noise ratio. The improvement allowed pairs of molecules separated by approximately 15 nm to be reliably and repeatedly resolved, thus demonstrating the first true Rayleigh resolution test for near-field images of single molecules. The potential of this technique for biological applications was demonstrated with an experiment that measured the helical rise of A-form DNA. PMID:17280412

  11. Wavelength encoded polarization measurements for simultaneous spectral and polarimetric characterization in near field

    NASA Astrophysics Data System (ADS)

    Patel, H. S.; Swami, M. K.; Kushwaha, P. K.; Uppal, A.; Gupta, P. K.

    2016-08-01

    We report a scheme for polarization sensitive near field imaging of nanostructured samples by making use of broadband polarized near field illumination and detection of polarization states of scattered light by a spectrally encoded analyzer. The analyzer comprising a combination of polarizer, a multi-order waveplate and a broadband quarter waveplate allows analysis of the spectrally encoded polarization states of scattered light for characterization of the polarization properties of nano structures from a single image scan. The scheme was validated by measuring the near field polarization parameters of silver nanowires. The approach allows simultaneous measurement of polarization characteristics as well as spectral features of the nano materials.

  12. Phase stabilized homodyne of infrared scattering type scanning near-field optical microscopy

    SciTech Connect

    Xu, Xiaoji G.; Gilburd, Leonid; Walker, Gilbert C.

    2014-12-29

    Scattering type scanning near-field optical microscopy (s-SNOM) allows sub diffraction limited spatial resolution. Interferometric homodyne detection in s-SNOM can amplify the signal and extract vibrational responses based on sample absorption. A stable reference phase is required for a high quality homodyne-detected near-field signal. This work presents the development of a phase stabilization mechanism for s-SNOM to provide stable homodyne conditions. The phase stability is found to be better than 0.05 rad for the mid infrared light source. Phase stabilization results in improved near field images and vibrational spectroscopies. Spatial inhomogeneities of the boron nitride nanotubes are measured and compared.

  13. A quasi-optical vector near-field measurement system at terahertz band.

    PubMed

    Lou, Zheng; Hu, Jie; Zhou, Kang-Min; Miao, Wei; Shi, Sheng-Cai

    2014-06-01

    This paper describes a vector near-field measurement system at terahertz band based on a high sensitivity superconducting receiver equipped with a quasi-optical probe for high resolution near-field sensing. A novel single-receiver rather than commonly used dual-receiver configuration is adopted for vector measurement. Performances of the measurement system including stability and dynamic range are studied. Vector near-field measurement of a diagonal feedhorn at 850 GHz is presented and shows good agreement with simulation and direct far-field measurement. PMID:24985832

  14. Generation of nearly 3D-unpolarized evanescent optical near fields using total internal reflection.

    PubMed

    Hassinen, Timo; Popov, Sergei; Friberg, Ari T; Setälä, Tero

    2016-07-01

    We analyze the time-domain partial polarization of optical fields composed of two evanescent waves created in total internal reflection by random electromagnetic beams with orthogonal planes of incidence. We show that such a two-beam configuration enables to generate nearly unpolarized, genuine three-component (3D) near fields. This result complements earlier studies on spectral polarization, which state that at least three symmetrically propagating beams are required to produce a 3D-unpolarized near field. The degree of polarization of the near field can be controlled by adjusting the polarization states and mutual correlation of the incident beams. PMID:27367071

  15. Near-field microscope probe for far infrared time domain measurements

    NASA Astrophysics Data System (ADS)

    Mitrofanov, O.; Brener, I.; Wanke, M. C.; Ruel, R. R.; Wynn, J. D.; Bruce, A. J.; Federici, J.

    2000-07-01

    A near-field probe fabrication technique for far-infrared frequencies based on photoconducting antennas is developed. A subwavelength-size field source is accomplished by means of an aperture and protruding high refractive index tip. The near-field probe is tested by using free space traveling electromagnetic pulses with a broadband spectrum in the range of 0.3-1.5 THz. A spatial resolution of 60 μm is achieved for a 50 μm aperture. The described probe may be used for near-field transmission microscopy in illumination and collection modes. Resolution may be further improved by means of a smaller aperture.

  16. Direct subwavelength imaging and control of near-field localization in individual silver nanocubes

    SciTech Connect

    Mårsell, Erik; Svärd, Robin; Miranda, Miguel; Guo, Chen; Harth, Anne; Lorek, Eleonora; Mauritsson, Johan; Arnold, Cord L.; L'Huillier, Anne; Mikkelsen, Anders; Losquin, Arthur; Xu, Hongxing

    2015-11-16

    We demonstrate the control of near-field localization within individual silver nanocubes through photoemission electron microscopy combined with broadband, few-cycle laser pulses. We find that the near-field is concentrated at the corners of the cubes, and that it can be efficiently localized to different individual corners depending on the polarization of the incoming light. The experimental results are confirmed by finite-difference time-domain simulations, which also provide an intuitive picture of polarization dependent near-field localization in nanocubes.

  17. Investigation of Coupled Processes and Impact of High Temperature Limits in Argillite Rock

    SciTech Connect

    Zheng, Liange; Rutqvist, Jonny; Kim, Kunhwi; Houseworth, Jim

    2015-07-01

    The focus of research within the UFD Campaign is on repository-induced interactions that may affect the key safety characteristics of an argillaceous rock. These include thermal-hydrological-mechanical-chemical (THMC) process interactions that occur as a result of repository construction and waste emplacement. Some of the key questions addressed in this report include the development of fracturing in the excavation damaged zone (EDZ) and THMC effects on the near-field argillaceous rock and buffer minerals and petrophysical characteristics, particularly the impacts of induced temperature rise caused by waste heat.

  18. Near-field thermal emission between corrugated surfaces separated by nano-gaps

    NASA Astrophysics Data System (ADS)

    Didari, Azadeh; Pinar Mengüç, M.

    2015-06-01

    Near-field thermal radiation with its many potential applications in different fields requires a thorough understanding for the development of new devices. In this paper, we report that near-field thermal emission between two parallel SiC thin films separated by a nano-gap, supporting surface phonon polaritons, as modeled via Finite Difference Time Domain Method (FDTD), can be enhanced when structured nanoparticles of different shapes and sizes are present on the surface of the emitting films. We compare different nano-particle shapes and discuss the configurations, which have the highest impact on the enhancement of near-field thermal emission and on the near-field heat flux. Convolutional Perfectly Matched Layer (CPML) boundary condition is used as the boundary condition of choice as it was determined to give the most accurate results compared against the other methodologies when working with sub-wavelength structures.

  19. Scanning near-field thermoelectric microscopy for subsurface nanoscale thermoelectric behavior

    NASA Astrophysics Data System (ADS)

    Xu, K. Q.; Zeng, H. R.; Zhao, K. Y.; Li, G. R.; Shi, X.; Chen, L. D.

    2016-05-01

    A novel scanning near-field thermoelectric microscopy (STeM) was proposed and developed for characterizing subsurface, nanoscale Seebeck coefficient of thermoelectric energy materials. In STeM, near-field evanescent thermal wave was induced around the thermal probe's contact with the thermoelectric sample's surface via a periodically modulated heated thermal probe, giving rise to a thermoelectric near-field interaction with simultaneous excitation of three harmonic signals for local Seebeck coefficient derivation. The near-field STeM was capable of characterizing local Seebeck coefficient of thermoelectric materials with high lateral resolution at nanometer scale and more importantly provides a convenient, powerful tool for quantitative characterization of subsurface nanoscale thermoelectric properties.

  20. A survey of near-field testing methods for large aperture antennas and future trends

    NASA Technical Reports Server (NTRS)

    Newell, A. C.

    1983-01-01

    In recent years, a near-field antenna measurements have progressed from theoretical concepts to a wide variety of operational measurement systems. The current status of this work is summarized and its possible application to large space antennas is discussed.

  1. On the use of Si-based nanohole arrays as near-field biochips

    SciTech Connect

    Eberle, H.-G.; Dressler, C; Beuthan, J; Mueller, G

    2002-11-30

    Near-field biochips based on nanohole arrays produced in silicon wafers are described and the first studies of cells and DNA with the help of a laser scanning microscope are presented. (laser biology and medicine)

  2. Optimization and maximum potential of optical antennae in near-field enhancement.

    PubMed

    Chen, PingPing; Liu, Ju; Wang, Li; Jin, Kuijuan; Yin, Yan; Li, ZhiYuan

    2015-06-20

    We investigate four types of gold nanoantennae (the monopole, the dipole, the cone-shaped, and the cone-bowtie antenna), under a fixed working wavelength. The finite-difference time-domain (FDTD) simulations show that the near-field enhancement values do not increase monotonously when the antennae sizes decrease, and optimization conditions vary with the antenna shapes. We also propose a distributed dipole ring model to analytically calculate the near field. The size condition for the strongest enhancement is the compromising result of the total radiated energy and the near-field distribution factor. Assuming the cone-bowtie antenna is the best for high enhancement, the maximum potential in near-field enhancement is 2×10(5) for a linear signal or 4×10(10) for typical nonlinear signals. PMID:26193035

  3. Father responsivity: couple processes and the coconstruction of fatherhood.

    PubMed

    Matta, Dana Shawn; Knudson-Martin, Carmen

    2006-03-01

    Forty in-depth interviews of heterosexual parents of children 5 five years of age and younger are analyzed using a qualitative grounded theory approach to understand how couples coproduce fatherhood within their day-to-day relationships and in social, cultural, and economic contexts. The analysis identifies the construct "responsivity" as a central process through which, to varying degrees, fathers are aware of the needs of their wives and children and able to take an active part in meeting them. Three groups of fathers are examined according to their level of responsivity: low, moderate, and high. Factors influencing degree of father responsivity include gender constructions, power and the wife's influence, attunement, work schedules, and emotional tradeoffs. Implications for practice are suggested. PMID:16615251

  4. Computational Diagnostic Techniques for Electromagnetic Scattering: Analytical Imaging, Near Fields, and Surface Currents

    NASA Technical Reports Server (NTRS)

    Hom, Kam W.; Talcott, Noel A., Jr.; Shaeffer, John

    1997-01-01

    This paper presents three techniques and the graphics implementations which can be used as diagnostic aides in the design and understanding of scattering structures: Imaging, near fields, and surface current displays. The imaging analysis is a new bistatic k space approach which has potential for much greater information than standard experimental approaches. The near field and current analysis are implementations of standard theory while the diagnostic graphics displays are implementations exploiting recent computer engineering work station graphics libraries.

  5. The near-field acoustic levitation of high-mass rotors

    SciTech Connect

    Hong, Z. Y.; Lü, P.; Geng, D. L.; Zhai, W.; Yan, N.; Wei, B.

    2014-10-15

    Here we demonstrate that spherical rotors with 40 mm diameter and 0-1 kg mass can be suspended more than tens of micrometers away from an ultrasonically vibrating concave surface by near-field acoustic radiation force. Their rotating speeds exceed 3000 rpm. An acoustic model has been developed to evaluate the near-field acoustic radiation force and the resonant frequencies of levitation system. This technique has potential application in developing acoustic gyroscope.

  6. Terahertz near-field imaging of surface plasmon waves in graphene structures

    DOE PAGESBeta

    Mitrofanov, O.; Yu, W.; Thompson, R. J.; Jiang, Y.; Greenberg, Z. J.; Palmer, J.; Brener, I.; Pan, W.; Berger, C.; de Heer, W. A.; et al

    2015-09-08

    In this study, we introduce a near-field scanning probe terahertz (THz) microscopy technique for probing surface plasmon waves on graphene. Based on THz time-domain spectroscopy method, this near-field imaging approach is well suited for studying the excitation and evolution of THz plasmon waves on graphene as well as for mapping of graphene properties at THz frequencies on the sub-wavelength scale.

  7. Experimental demonstration of multiwire endoscopes capable of manipulating near-fields with subwavelength resolution

    NASA Astrophysics Data System (ADS)

    Belov, Pavel A.; Palikaras, George K.; Zhao, Yan; Rahman, Atiqur; Simovski, Constantin R.; Hao, Yang; Parini, Clive

    2010-11-01

    Endoscopes formed by arrays of metallic wires can transmit, magnify, and demagnify near-field distributions with subwavelength resolution. Our experiments demonstrate that despite their small apertures, the parallel multiwire endoscopes can be used to transmit near-field distributions with a resolution of five thousandths of a wavelength to a distance of a half-wavelength in the microwave frequency range, and tapered multiwire endoscopes with flat input and output interfaces provide threefold image magnification and demagnification.

  8. Lift-Off Acoustics Prediction of Clustered Rocket Engines in the Near Field

    NASA Technical Reports Server (NTRS)

    Vu, Bruce; Plotkin, Ken

    2010-01-01

    This slide presentation presents a method of predicting acoustics during lift-off of the clustered rocket engines in the near field. Included is a definition of the near field, and the use of deflectors and shielding. There is discussion about the use of PAD, a software system designed to calculate the acoustic levels from the lift of of clustered rocket enginee, including updates to extend the calculation to directivity, water suppression, and clustered nozzles.

  9. The near-field acoustic levitation of high-mass rotors

    NASA Astrophysics Data System (ADS)

    Hong, Z. Y.; Lü, P.; Geng, D. L.; Zhai, W.; Yan, N.; Wei, B.

    2014-10-01

    Here we demonstrate that spherical rotors with 40 mm diameter and 0-1 kg mass can be suspended more than tens of micrometers away from an ultrasonically vibrating concave surface by near-field acoustic radiation force. Their rotating speeds exceed 3000 rpm. An acoustic model has been developed to evaluate the near-field acoustic radiation force and the resonant frequencies of levitation system. This technique has potential application in developing acoustic gyroscope.

  10. The near-field acoustic levitation of high-mass rotors.

    PubMed

    Hong, Z Y; Lü, P; Geng, D L; Zhai, W; Yan, N; Wei, B

    2014-10-01

    Here we demonstrate that spherical rotors with 40 mm diameter and 0-1 kg mass can be suspended more than tens of micrometers away from an ultrasonically vibrating concave surface by near-field acoustic radiation force. Their rotating speeds exceed 3000 rpm. An acoustic model has been developed to evaluate the near-field acoustic radiation force and the resonant frequencies of levitation system. This technique has potential application in developing acoustic gyroscope. PMID:25362441

  11. Anomalous diffusion and scaling in coupled stochastic processes

    SciTech Connect

    Bel, Golan; Nemenman, Ilya

    2009-01-01

    Inspired by problems in biochemical kinetics, we study statistical properties of an overdamped Langevin processes with the friction coefficient depending on the state of a similar, unobserved, process. Integrating out the latter, we derive the Pocker-Planck the friction coefficient of the first depends on the state of the second. Integrating out the latter, we derive the Focker-Planck equation for the probability distribution of the former. This has the fonn of diffusion equation with time-dependent diffusion coefficient, resulting in an anomalous diffusion. The diffusion exponent can not be predicted using a simple scaling argument, and anomalous scaling appears as well. The diffusion exponent of the Weiss-Havlin comb model is derived as a special case, and the same exponent holds even for weakly coupled processes. We compare our theoretical predictions with numerical simulations and find an excellent agreement. The findings caution against treating biochemical systems with unobserved dynamical degrees of freedom by means of standandard, diffusive Langevin descritpion.

  12. Point-by-point near-field optical energy deposition around plasmonic nanospheres in absorbing media.

    PubMed

    Harrison, R K; Ben-Yakar, Adela

    2015-08-01

    Here we investigate the effects of absorbing media on plasmon-enhanced near-field optical energy deposition. We find that increasing absorption by the medium results in increased particle scattering at the expense of particle absorption, and that much of this increased particle scattering is absorbed by the medium close to the particle surface. We present an analytical method for evaluating the spatial distribution of near-field enhanced absorption surrounding plasmonic metal nanospheres in absorbing media using a new point-by-point method. We propose criteria to define relevant near-field boundaries and calculate the properties of the local absorption enhancement, which redistributes absorption to the near-field and decays asymptotically as a function of the distance from the particle to background levels. Using this method, we performed a large-scale parametric study to understand the effect of particle size and wavelength on the near-field absorption for gold nanoparticles in aqueous media and silicon, and identified conditions that are relevant to enhanced local infrared absorption in silicon. The presented approach provides insight into the local energy transfer around plasmonic nanoparticles for predicting near-field effects for advanced concepts in optical sensing, thin-film solar cells, nonlinear imaging, and photochemical applications. PMID:26367296

  13. Microwave Imaging and Holographic Diagnostic to Antennas in Cylindrical Near-Field Measurement

    NASA Technical Reports Server (NTRS)

    Hussein, Ziad A.

    1995-01-01

    In this paper, the issues pertaining to microwave imaging and holographic diagnostic to antennas in cylindrical near-field measurements are addressed. The theoretical approach is based on expanding the work in [1] and [2] where a cylindrical wave expansion of the field on a cylindrical near-field surface is given. The sampling probe is modeled by its equivalent aperture current (idealized circular aperture) and incorporated into the near-field to far-field transformation. The method of steepest decent is applied to obtain the far-field. In its implementation, however, one could specify directly the angular spectrum at which the far-field is desired to be calculated without resorting to interpolation. The microwave imaging and holographic diagnostic is based on back projection where a plane wave expansion of the far-field is obtained. This approach necessitates the knowledge of the far-field at exact angular spectrum resulting from application of 2-D FFT. Hence, we were able to construct simply the near-field on a plane not necessarily on the aperture plane of the test antenna but also on planes perpendicular to the aperture plane [3]. And a 3-D high resolution and high precision antenna imaging of the test antenna is obtained from cylindrical near-field simulated measurements. In addition microwave holographic diagnostic of large NASA scatterometer radar antenna obtained from measured near-field on a cylindrical surface will be given if time permits.

  14. Mountain-Scale Coupled Processes (TH/THC/THM)

    SciTech Connect

    P. Dixon

    2004-02-09

    The purpose of this Model Report is to document the development of the Mountain-Scale Thermal-Hydrological (TH), Thermal-Hydrological-Chemical (THC), and Thermal-Hydrological-Mechanical (THM) Models and evaluate the effects of coupled TH/THC/THM processes on mountain-scale UZ flow at Yucca Mountain, Nevada. This Model Report was planned in ''Technical Work Plan (TWP) for: Performance Assessment Unsaturated Zone'' (BSC 2002 [160819], Section 1.12.7), and was developed in accordance with AP-SIII.10Q, Models. In this Model Report, any reference to ''repository'' means the nuclear waste repository at Yucca Mountain, and any reference to ''drifts'' means the emplacement drifts at the repository horizon. This Model Report provides the necessary framework to test conceptual hypotheses for analyzing mountain-scale hydrological/chemical/mechanical changes and predict flow behavior in response to heat release by radioactive decay from the nuclear waste repository at the Yucca Mountain site. The mountain-scale coupled TH/THC/THM processes models numerically simulate the impact of nuclear waste heat release on the natural hydrogeological system, including a representation of heat-driven processes occurring in the far field. The TH simulations provide predictions for thermally affected liquid saturation, gas- and liquid-phase fluxes, and water and rock temperature (together called the flow fields). The main focus of the TH Model is to predict the changes in water flux driven by evaporation/condensation processes, and drainage between drifts. The TH Model captures mountain-scale three dimensional (3-D) flow effects, including lateral diversion at the PTn/TSw interface and mountain-scale flow patterns. The Mountain-Scale THC Model evaluates TH effects on water and gas chemistry, mineral dissolution/precipitation, and the resulting impact to UZ hydrological properties, flow and transport. The THM Model addresses changes in permeability due to mechanical and thermal disturbances in

  15. High-order-harmonic generation by enhanced plasmonic near-fields in metal nanoparticles

    NASA Astrophysics Data System (ADS)

    Shaaran, T.; Ciappina, M. F.; Guichard, R.; Pérez-Hernández, J. A.; Roso, L.; Arnold, M.; Siegel, T.; Zaïr, A.; Lewenstein, M.

    2013-04-01

    We present theoretical investigations of high-order-harmonic generation (HHG) resulting from the interaction of noble gases with localized surface plasmons. These plasmonic near-fields are produced when a metal nanoparticle is subject to a few-cycle laser pulse. The enhanced field, which largely depends on the geometrical shape of the metallic nanostructure, has a strong spatial dependency. We demonstrate that the strong nonhomogeneity of this laser field plays an important role in the HHG process and leads to a significant increase of the harmonic-cutoff energy. In order to understand and characterize this feature, we include the functional form of the laser electric field obtained from recent attosecond streaking experiments [F. Süßmann and M. F. Kling, Proc. SPIE0277-786X10.1117/12.893551 8096, 80961C (2011)] in the time-dependent Schrödinger equation. By performing classical simulations of the HHG process we show consistency between them and the quantum-mechanical predictions. These allow us to understand the origin of the extended harmonic spectra as a selection of particular trajectory sets. The use of metal nanoparticles is an alternate way of generating coherent XUV light with a laser field whose characteristics can be synthesized locally.

  16. Near-field engineering of Fano resonances in a plasmonic assembly for maximizing CARS enhancements.

    PubMed

    He, Jinna; Fan, Chunzhen; Ding, Pei; Zhu, Shuangmei; Liang, Erjun

    2016-01-01

    Surface enhanced coherent anti-Stokes Raman scattering (SECARS) is a sensitive tool and promising for single molecular detection and chemical selective imaging. However, the enhancement factors (EF) were only 10~100 for colloidal silver and gold nanoparticles usually used as SECARS substrates. In this paper, we present a design of SECARS substrate consisting of three asymmetric gold disks and strategies for maximizing the EF by engineering near-field properties of the plasmonic Fano nanoassembly. It is found that the E-field "hot spots" corresponding to three different frequencies involved in SECARS process can be brought to the same spatial locations by tuning incident orientations, giving rise to highly confined SECARS "hot spots" with the EF reaching single-molecule sensitivity. Besides, an even higher EF of SECARS is achieved by introducing double Fano resonances in this plasmonic nanoassembly via further enlarging the sizes of the constituent disks. These findings put an important step forward to the plasmonic substrate design for SECARS as well as for other nonlinear optical processes. PMID:26861192

  17. Yucca Mountain near-field environment considerations for engineered barrier system design and performance

    SciTech Connect

    Wilder, D.G.

    1991-05-01

    The United States Department of Energy (DOE) is investigating the suitability of Yucca Mountain (YM) as a potential site for the nation`s first High-Level Nuclear Waste Repository. This responsibility includes materials testing and selections, design criteria development, waste form characterizations, performance assessments, and Near-Field (NF) environment characterization. These areas of responsibility are interrelated and to a large extent depend on environmental conditions surrounding the EBS components. The focus of this paper is to discuss what is currently known about the NF environment, particularly those aspects whose interaction with EBS components have significant impacts on the performance of the EBS and its ability to contribute to the isolation of radioactive waste. Reference designs and design/processes assumptions are used to evaluate the expected NF environmental conditions. This report will not focus on providing parameter values but rather on the processes that influence those parameters and on the impacts of those parameters on the performance of EBS components. Where values are given, they should be viewed as typical of YM as a whole but not necessarily representative of the actual NF environment conditions that surround the EBS components. 19 refs., 6 figs.

  18. Near-field engineering of Fano resonances in a plasmonic assembly for maximizing CARS enhancements

    NASA Astrophysics Data System (ADS)

    He, Jinna; Fan, Chunzhen; Ding, Pei; Zhu, Shuangmei; Liang, Erjun

    2016-02-01

    Surface enhanced coherent anti-Stokes Raman scattering (SECARS) is a sensitive tool and promising for single molecular detection and chemical selective imaging. However, the enhancement factors (EF) were only 10~100 for colloidal silver and gold nanoparticles usually used as SECARS substrates. In this paper, we present a design of SECARS substrate consisting of three asymmetric gold disks and strategies for maximizing the EF by engineering near-field properties of the plasmonic Fano nanoassembly. It is found that the E-field “hot spots” corresponding to three different frequencies involved in SECARS process can be brought to the same spatial locations by tuning incident orientations, giving rise to highly confined SECARS “hot spots” with the EF reaching single-molecule sensitivity. Besides, an even higher EF of SECARS is achieved by introducing double Fano resonances in this plasmonic nanoassembly via further enlarging the sizes of the constituent disks. These findings put an important step forward to the plasmonic substrate design for SECARS as well as for other nonlinear optical processes.

  19. Near-field engineering of Fano resonances in a plasmonic assembly for maximizing CARS enhancements

    PubMed Central

    He, Jinna; Fan, Chunzhen; Ding, Pei; Zhu, Shuangmei; Liang, Erjun

    2016-01-01

    Surface enhanced coherent anti-Stokes Raman scattering (SECARS) is a sensitive tool and promising for single molecular detection and chemical selective imaging. However, the enhancement factors (EF) were only 10~100 for colloidal silver and gold nanoparticles usually used as SECARS substrates. In this paper, we present a design of SECARS substrate consisting of three asymmetric gold disks and strategies for maximizing the EF by engineering near-field properties of the plasmonic Fano nanoassembly. It is found that the E-field “hot spots” corresponding to three different frequencies involved in SECARS process can be brought to the same spatial locations by tuning incident orientations, giving rise to highly confined SECARS “hot spots” with the EF reaching single-molecule sensitivity. Besides, an even higher EF of SECARS is achieved by introducing double Fano resonances in this plasmonic nanoassembly via further enlarging the sizes of the constituent disks. These findings put an important step forward to the plasmonic substrate design for SECARS as well as for other nonlinear optical processes. PMID:26861192

  20. Evolutionary games of condensates in coupled birth-death processes

    NASA Astrophysics Data System (ADS)

    Weber, Markus F.; Knebel, Johannes; Krueger, Torben; Frey, Erwin

    2015-03-01

    Condensation phenomena occur in many systems, both in a classical and a quantum mechanical context. Typically, the entities that constitute a system collectively concentrate in one distinct state during condensation. For example, cooling of an equilibrated bosonic gas may lead to condensation into the quantum ground state. Notably, the mathematical theory of this Bose-Einstein condensation is not limited to quantum theory but was also successfully applied to condensation in random networks. In our work, we follow the opposite path. We apply the theory of evolutionary dynamics to describe condensation in a bosonic system that is driven and dissipative. It was shown that the system may condense into multiple quantum states, but into which states has remained elusive. We find that vanishing of relative entropy production determines these states. We illuminate the physical principles underlying the condensation and show that the condensates do not need to be static but may engage in ``evolutionary games'' with exchange of particles. On the mathematical level, the condensation is described by coupled birth-death processes. The generic structure of these processes implies that our results also apply to condensation in other systems, ranging from population biology to chemical kinetics.

  1. 3-D Modelling of Electromagnetic, Thermal, Mechanical and Metallurgical Couplings in Metal Forming Processes

    SciTech Connect

    Chenot, Jean-Loup; Bay, Francois

    2007-04-07

    The different stages of metal forming processes often involve - beyond the mechanical deformations processes - other physical coupled problems, such as heat transfer, electromagnetism or metallurgy. The purpose of this paper is to focus on problems involving electromagnetic couplings. After a brief recall on electromagnetic modeling, we shall then focus on induction heating processes and present some results regarding heat transfer, as well as mechanical couplings. A case showing coupling for metallurgic microstructure evolution will conclude this paper.

  2. A compact, short-pulse laser for near-field, range-gated imaging

    SciTech Connect

    Zutavern, F.J.; Helgeson, W.D.; Loubriel, G.M.; Yates, G.J.; Gallegos, R.A.; McDonald, T.E.

    1996-12-31

    This paper describes a compact laser, which produces high power, wide-angle emission for a near-field, range-gated, imaging system. The optical pulses are produced by a 100 element laser diode array (LDA) which is pulsed with a GaAs, photoconductive semiconductor switch (PCSS). The LDA generates 100 ps long, gain-switched, optical pulses at 904 nm when it is driven with 3 ns, 400 A, electrical pulses from a high gain PCSS. Gain switching is facilitated with this many lasers by using a low impedance circuit to drive an array of lasers, which are connected electrically in series. The total optical energy produced per pulse is 10 microjoules corresponding to a total peak power of 100 kW. The entire laser system, including prime power (a nine volt battery), pulse charging, PCSS, and LDA, is the size of a small, hand-held flashlight. System lifetime, which is presently limited by the high gain PCSS, is an active area of research and development. Present limitations and potential improvements will be discussed. The complete range-gated imaging system is based on complementary technologies: high speed optical gating with intensified charge coupled devices (ICCD) developed at Los Alamos National Laboratory (LANL) and high gain, PCSS-driven LDAs developed at Sandia National Laboratories (SNL). The system is designed for use in highly scattering media such as turbid water or extremely dense fog or smoke. The short optical pulses from the laser and high speed gating of the ICCD are synchronized to eliminate the back-scattered light from outside the depth of the field of view (FOV) which may be as short as a few centimeters. A high speed photodiode can be used to trigger the intensifier gate and set the range-gated FOV precisely on the target. The ICCD and other aspects of the imaging system are discussed in a separate paper.

  3. High-resolution apertureless near-field optical imaging using gold nanosphere probes.

    PubMed

    Kim, Zee Hwan; Leone, Stephen R

    2006-10-12

    An apertureless near-field scanning optical microscope (ANSOM) that utilizes the enhanced field around a gold nanosphere, which is attached to the end of an atomic force microscope (AFM) tip, is used to image the local dielectric constant of the patterned metallic surfaces and local electric field around plasmonic nanosphere samples. A colloidal gold nanosphere (approximately 50 nm diameter) is linked to the extremity of the conventional etched-silicon probe. The scattering of laser radiation (633 or 532 nm) is modulated by the oscillating nanosphere-functionalized silicon tip, and the scattered radiation is detected. The approach curve (scattering intensity as a function of the tip-sample distance), the polarization dependence (scattering intensity as a function of the excitation polarization direction), and ANSOM image contrast confirm that the spherical nanosphere attached to the silicon tip acts as a point dipole that interacts with the sample surface via a dipole-dipole coupling, in which the dipole created by the field at the tip interacts with its own image dipole in the sample. The image obtained with the nanoparticle functionalized tip provides a dielectric map of the sample surface with a spatial resolution better than 80 nm. In addition, we show that the functionalized tip is capable of imaging the local electric field distribution above the plasmonic nanosphere samples. Overall, the result shows that high-resolution ANSOM is possible without the aid of the lightning-rod effect. With an improved tip-fabrication method, we believe that the method can provide a versatile high-resolution chemical imaging that is not available from usual forms of ANSOM. PMID:17020365

  4. Coherent interaction with two-level fluctuators using near field scanning microwave microscopy

    PubMed Central

    de Graaf, S. E.; Danilov, A. V.; Kubatkin, S. E.

    2015-01-01

    Near field Scanning Microwave Microscopy (NSMM) is a scanning probe technique that non-invasively can obtain material properties on the nano-scale at microwave frequencies. While focus has been on developing room-temperature systems it was recently shown that this technique can potentially reach the quantum regime, opening up for applications in materials science and device characterization in solid state quantum information processing. In this paper we theoretically investigate this new regime of NSMM. Specifically we show that interaction between a resonant NSMM probe and certain types of two-level systems become possible when the NSMM probe operates in the (sub-) single photon regime, and we expect a high signal-to-noise ratio if operated under the right conditions. This would allow to detect single atomic material defects with energy splittings in the GHz range with nano-scale resolution, provided that individual defects in the material under study are well enough separated. We estimate that this condition is fulfilled for materials with loss tangents below tan δ ∼ 10−3 which holds for materials used in today’s quantum circuits and devices where typically tan δ < 10−5. We also propose several extensions to a resonant NSMM that could improve sensitivity and functionality also for microscopes operating in a high power regime. PMID:26597218

  5. Time-Domain Optimized Near-Field Estimator for Ultrasound Imaging: Initial Development and Results

    PubMed Central

    Ellis, Michael A.; Walker, William F.

    2009-01-01

    For nearly four decades, adaptive beamforming (ABF) algorithms have been applied in RADAR and SONAR signal processing. These algorithms reduce the contribution of undesired off-axis signals while maintaining a desired response along a specific look direction. Typically, higher resolution and contrast is attainable using adaptive beamforming at the price of an increased computational load. In this paper, we describe a novel ABF designed for medical ultrasound, named the Time-domain Optimized Near-field Estimator (TONE). We performed a series of simulations using synthetic ultrasound data to test the performance of this algorithm and compared it to conventional, data independent, delay and sum beamforming (CBF) method. We also performed experiments using a Philips SONOS 5500 phased array imaging system. CBF was applied using the default parameters of the Philips scanner, whereas TONE was applied on per channel, unfocused data using an unfocused transmit beam. TONE images were reconstructed at a sampling of 67 µm laterally and 19 µm axially. The results obtained for a series of five 20-µm wires in a water tank show a significant improvement in spatial resolution when compared to CBF. We also analyzed the performance of TONE as a function of speed of sound errors and array sparsity, finding it robust to both. PMID:18270066

  6. Coherent interaction with two-level fluctuators using near field scanning microwave microscopy

    NASA Astrophysics Data System (ADS)

    de Graaf, S. E.; Danilov, A. V.; Kubatkin, S. E.

    2015-11-01

    Near field Scanning Microwave Microscopy (NSMM) is a scanning probe technique that non-invasively can obtain material properties on the nano-scale at microwave frequencies. While focus has been on developing room-temperature systems it was recently shown that this technique can potentially reach the quantum regime, opening up for applications in materials science and device characterization in solid state quantum information processing. In this paper we theoretically investigate this new regime of NSMM. Specifically we show that interaction between a resonant NSMM probe and certain types of two-level systems become possible when the NSMM probe operates in the (sub-) single photon regime, and we expect a high signal-to-noise ratio if operated under the right conditions. This would allow to detect single atomic material defects with energy splittings in the GHz range with nano-scale resolution, provided that individual defects in the material under study are well enough separated. We estimate that this condition is fulfilled for materials with loss tangents below tan δ ˜ 10-3 which holds for materials used in today’s quantum circuits and devices where typically tan δ < 10-5. We also propose several extensions to a resonant NSMM that could improve sensitivity and functionality also for microscopes operating in a high power regime.

  7. Coherent interaction with two-level fluctuators using near field scanning microwave microscopy.

    PubMed

    de Graaf, S E; Danilov, A V; Kubatkin, S E

    2015-01-01

    Near field Scanning Microwave Microscopy (NSMM) is a scanning probe technique that non-invasively can obtain material properties on the nano-scale at microwave frequencies. While focus has been on developing room-temperature systems it was recently shown that this technique can potentially reach the quantum regime, opening up for applications in materials science and device characterization in solid state quantum information processing. In this paper we theoretically investigate this new regime of NSMM. Specifically we show that interaction between a resonant NSMM probe and certain types of two-level systems become possible when the NSMM probe operates in the (sub-) single photon regime, and we expect a high signal-to-noise ratio if operated under the right conditions. This would allow to detect single atomic material defects with energy splittings in the GHz range with nano-scale resolution, provided that individual defects in the material under study are well enough separated. We estimate that this condition is fulfilled for materials with loss tangents below tan δ ∼ 10(-3) which holds for materials used in today's quantum circuits and devices where typically tan δ < 10(-5). We also propose several extensions to a resonant NSMM that could improve sensitivity and functionality also for microscopes operating in a high power regime. PMID:26597218

  8. Application of near-field microwave sensing techniques for segregation detection in concrete members

    NASA Astrophysics Data System (ADS)

    Bois, K. J.; Benally, A. D.; Zoughi, R.; Nowak, P. S.

    2000-05-01

    In this presentation, a simple, low-cost near-field microwave nondestructive inspection technique for segregation detection in concrete members is presented. This process employs information from the measured magnitude of reflection coefficient at the aperture of an open-ended rectangular waveguide sensor. These measurements, whose results will be presented, were conducted using a Hewlett-Packard HP8510B network analyzer. However, in practice a simple and relatively inexpensive inspection apparatus constructed from discrete microwave components can easily be employed. It is shown that the standard deviation of magnitude of reflection coefficient measurement is linearly correlated with the aggregate density in concrete. Furthermore, for concrete in which the aggregate has segregated, this measurable parameter will change as a function of vertical position of the microwave scan. Results correlating the microwave measurements to the actual aggregate density of a well consolidated concrete specimen and a specimen in which the aggregate has segregated will be presented. Finally, the simple and low cost application of this method for in situ detection of aggregate segregation in concrete structures will be discussed.

  9. Near-field acoustic holography using sparse regularization and compressive sampling principles.

    PubMed

    Chardon, Gilles; Daudet, Laurent; Peillot, Antoine; Ollivier, François; Bertin, Nancy; Gribonval, Rémi

    2012-09-01

    Regularization of the inverse problem is a complex issue when using near-field acoustic holography (NAH) techniques to identify the vibrating sources. This paper shows that, for convex homogeneous plates with arbitrary boundary conditions, alternative regularization schemes can be developed based on the sparsity of the normal velocity of the plate in a well-designed basis, i.e., the possibility to approximate it as a weighted sum of few elementary basis functions. In particular, these techniques can handle discontinuities of the velocity field at the boundaries, which can be problematic with standard techniques. This comes at the cost of a higher computational complexity to solve the associated optimization problem, though it remains easily tractable with out-of-the-box software. Furthermore, this sparsity framework allows us to take advantage of the concept of compressive sampling; under some conditions on the sampling process (here, the design of a random array, which can be numerically and experimentally validated), it is possible to reconstruct the sparse signals with significantly less measurements (i.e., microphones) than classically required. After introducing the different concepts, this paper presents numerical and experimental results of NAH with two plate geometries, and compares the advantages and limitations of these sparsity-based techniques over standard Tikhonov regularization. PMID:22978881

  10. Study on Transient Properties of Levitated Object in Near-Field Acoustic Levitation

    NASA Astrophysics Data System (ADS)

    Jia, Bing; Chen, Chao; Zhao, Chun-Sheng

    2011-12-01

    A new approach to the study on the transient properties of the levitated object in near-field acoustic levitation (NFAL) is presented. In this article, the transient response characteristics, including the levitated height of an object with radius of 24 mm and thickness of 5 mm, the radial velocity and pressure difference of gas at the boundary of clearance between the levitated object and radiating surface (squeeze film), is calculated according to several velocity amplitudes of radiating surface. First, the basic equations in fluid areas on Arbitrary Lagrange—Euler (ALE) form are numerically solved by using streamline upwind petrov galerkin (SUPG) finite elements method. Second, the formed algebraic equations and solid control equations are solved by using synchronous alternating method to gain the transient messages of the levitated object and gas in the squeeze film. Through theoretical and numerical analyses, it is found that there is a oscillation time in the transient process and that the response time does not simply increase with the increasing of velocity amplitudes of radiating surface. More investigations in this paper are helpful for the understanding of the transient properties of levitated object in NFAL, which are in favor of enhancing stabilities and responsiveness of levitated object.

  11. Nano-scale imaging and spectroscopy of plasmonic systems, thermal near-fields, and phase separation in complex oxides

    NASA Astrophysics Data System (ADS)

    Jones, Andrew C.

    -rods. Strong spatial field variation on lengths scales as short as 20 nm is observed associated with the dipolar and quadrupolar modes of both systems with details sensitively depending on the nanoparticle structure and environment. In light of recent publications predicting distinct spectral characteristics of thermal electromagnetic near-fields, I demonstrate the extension of s-SNOM techniques through the implementation of a heated atomic force microscope (AFM) tip acting as its own intrinsic light source for the characterization of thermal near-fields. Here, I detail the spectrally distinct and orders of magnitude enhanced resonant spectral near-field energy density associated with vibrational, phonon, and phonon-polariton modes. Modeling the thermal light scattering by the AFM, the scattering cross-section for thermal light may be related to the electromagnetic local density of states (EM-LDOS) above a surface. Lastly, the unique capability of s-SNOM techniques to characterize phase separation phenomena in correlated electron systems is discussed. This measurement capability provides new microscopic insight into the underlying mechanisms of the rich phase transition behavior exhibited by these materials. As a specific example, the infrared s-SNOM mapping of the metal-insulator transition and the associated nano-domain formation in individual VO2 micro-crystals subject to substrate stress is presented. Our results have important implications for the interpretation of the investigations of conventional polycrystalline thin films where the mutual interaction of constituent crystallites may affect the nature of phase separation processes.

  12. Modeling of coupled geochemical and transport processes: An overview

    SciTech Connect

    Carnahan, C.L.

    1989-10-01

    Early coupled models associated with fluid flow and solute transport have been limited by assumed conditions of constant temperature, fully saturated fluid flow, and constant pore fluid velocity. Developments including coupling of chemical reactions to variable fields of temperature and fluid flow have generated new requirements for experimental data. As the capabilities of coupled models expand, needs are created for experimental data to be used for both input and validation. 25 refs.

  13. Two-photon absorption induced by electric field gradient of optical near-field and its application to photolithography

    SciTech Connect

    Yamaguchi, Maiku; Kawazoe, Tadashi; Yatsui, Takashi; Nobusada, Katsuyuki

    2015-05-11

    An electric field gradient is an inherent property of the optical near-field (ONF). We investigated its effect on electron excitation in a quantum dot via model calculations combining a density matrix formalism and a classical Lorentz model. The electric field gradient of the ONF was found to cause two-photon absorption by an unusual mechanism. Furthermore, the absorption exhibits a nonmonotonic dependence on the spatial arrangement of the nanosystem, completely different from that of conventional two-photon absorption induced by an intense electric field. The present two-photon absorption process was verified in a previous experimental observation by reinterpreting the results of ONF photolithography.

  14. Evolutionary games of condensates in coupled birth–death processes

    PubMed Central

    Knebel, Johannes; Weber, Markus F.; Krüger, Torben; Frey, Erwin

    2015-01-01

    Condensation phenomena arise through a collective behaviour of particles. They are observed in both classical and quantum systems, ranging from the formation of traffic jams in mass transport models to the macroscopic occupation of the energetic ground state in ultra-cold bosonic gases (Bose–Einstein condensation). Recently, it has been shown that a driven and dissipative system of bosons may form multiple condensates. Which states become the condensates has, however, remained elusive thus far. The dynamics of this condensation are described by coupled birth–death processes, which also occur in evolutionary game theory. Here we apply concepts from evolutionary game theory to explain the formation of multiple condensates in such driven-dissipative bosonic systems. We show that the vanishing of relative entropy production determines their selection. The condensation proceeds exponentially fast, but the system never comes to rest. Instead, the occupation numbers of condensates may oscillate, as we demonstrate for a rock–paper–scissors game of condensates. PMID:25908384

  15. Scattering-type scanning near-field optical microscopy with reconstruction of vertical interaction.

    PubMed

    Wang, Le; Xu, Xiaoji G

    2015-01-01

    Scattering-type scanning near-field optical microscopy provides access to super-resolution spectroscopic imaging of the surfaces of a variety of materials and nanostructures. In addition to chemical identification, it enables observations of nano-optical phenomena, such as mid-infrared plasmons in graphene and phonon polaritons in boron nitride. Despite the high lateral spatial resolution, scattering-type near-field optical microscopy is not able to provide characteristics of near-field responses in the vertical dimension, normal to the sample surface. Here, we present an accurate and fast reconstruction method to obtain vertical characteristics of near-field interactions. For its first application, we investigated the bound electromagnetic field component of surface phonon polaritons on the surface of boron nitride nanotubes and found that it decays within 20 nm with a considerable phase change in the near-field signal. The method is expected to provide characterization of the vertical field distribution of a wide range of nano-optical materials and structures. PMID:26592949

  16. Scattering-type scanning near-field optical microscopy with reconstruction of vertical interaction

    NASA Astrophysics Data System (ADS)

    Wang, Le; Xu, Xiaoji G.

    2015-11-01

    Scattering-type scanning near-field optical microscopy provides access to super-resolution spectroscopic imaging of the surfaces of a variety of materials and nanostructures. In addition to chemical identification, it enables observations of nano-optical phenomena, such as mid-infrared plasmons in graphene and phonon polaritons in boron nitride. Despite the high lateral spatial resolution, scattering-type near-field optical microscopy is not able to provide characteristics of near-field responses in the vertical dimension, normal to the sample surface. Here, we present an accurate and fast reconstruction method to obtain vertical characteristics of near-field interactions. For its first application, we investigated the bound electromagnetic field component of surface phonon polaritons on the surface of boron nitride nanotubes and found that it decays within 20 nm with a considerable phase change in the near-field signal. The method is expected to provide characterization of the vertical field distribution of a wide range of nano-optical materials and structures.

  17. Design and Characterization of a Novel Near Field Detector for Three Dimensional X-ray Diffraction

    NASA Astrophysics Data System (ADS)

    Annett, Scott; Margulies, Lawrence; Dale, Darren; Kycia, Stefan

    Three dimensional x-ray diffraction microscopy (3DXRD) is a powerful technique that provides crystallographic and spatial information of a large number of grains in a sample simultaneously. A key component of a 3DXRD experiment is the near field detector which provides high resolution spatial information of the sample. A novel design for a near field detector was developed and characterized. This design, called the Quad Near Field Detector, utilizes four quadrants, each with a dedicated scintillating phosphor and optical microscope. A novel translation stage for focusing the microscopes was developed, tested, and implemented. The near field detector was calibrated and characterized at the Cornell High Energy Synchrotron Source. A flood field correction was developed for the detector to correct for variations in intensity response. Diffraction data of all four quadrants was able to reproduce the crystal orientation of the ruby calibrant. In conclusion, the design and implementation of the Quad Near Field Detector was a success and will be a useful tool for future 3DXRD experiments.

  18. Graphene-based platform for nano-scale infrared near-field spectroscopy of biological materials

    NASA Astrophysics Data System (ADS)

    Khatib, Omar; Wood, Joshua D.; Doidge, Gregory P.; Damhorst, Gregory L.; Rangarajan, Aniruddh; Bashir, Rashid; Pop, Eric; Lyding, Joseph W.; Basov, Dimitri N.

    2014-03-01

    In biological and life sciences, Fourier Transform Infrared (FTIR) spectroscopy serves as a noninvasive probe of vibrational fingerprints used to identify chemical and molecular species. Near-field spectroscopy, based on the illumination of an atomic force microscope (AFM) tip with an infrared laser, allows for determination of IR properties of a material at nanometer length scales. However, application of near-field IR spectroscopy to most biological systems has thus far been elusive. Physiological conditions required for experimentation are incompatible with typical implementations of nano-FTIR. Recently it became possible to trap water and small biomolecules underneath large-area graphene sheets grown by chemical vapor deposition (CVD). The graphene layer serves as an IR-transparent cover that allows for a near-field interrogation of the underlying layers. We present near-field nano-imaging and spectroscopy data of unencapsulated Tobacco Mosaic Viruses (TMV), compared to those sandwiched between two large-area graphene sheets, and discuss the applicability of near-field IR spectroscopy to trapped biomolecules in aqueous environments.

  19. Scattering-type scanning near-field optical microscopy with reconstruction of vertical interaction

    PubMed Central

    Wang, Le; Xu, Xiaoji G.

    2015-01-01

    Scattering-type scanning near-field optical microscopy provides access to super-resolution spectroscopic imaging of the surfaces of a variety of materials and nanostructures. In addition to chemical identification, it enables observations of nano-optical phenomena, such as mid-infrared plasmons in graphene and phonon polaritons in boron nitride. Despite the high lateral spatial resolution, scattering-type near-field optical microscopy is not able to provide characteristics of near-field responses in the vertical dimension, normal to the sample surface. Here, we present an accurate and fast reconstruction method to obtain vertical characteristics of near-field interactions. For its first application, we investigated the bound electromagnetic field component of surface phonon polaritons on the surface of boron nitride nanotubes and found that it decays within 20 nm with a considerable phase change in the near-field signal. The method is expected to provide characterization of the vertical field distribution of a wide range of nano-optical materials and structures. PMID:26592949

  20. THz near-field imaging of biological tissues employing synchrotron radiation (Invited Paper)

    NASA Astrophysics Data System (ADS)

    Schade, Ulrich; Holldack, Karsten; Martin, Michael C.; Fried, Daniel

    2005-04-01

    Terahertz scanning near-field infrared microscopy (SNIM) below 1 THz is demonstrated. The near-field technique benefits from the broadband and highly brilliant coherent synchrotron radiation (CSR) from an electron storage ring and from a detection method based on locking on to the intrinsic time structure of the synchrotron radiation. The scanning microscope utilizes conical waveguides as near-field probes with apertures smaller than the wavelength. Different cone approaches have been investigated to obtain maximum transmittance. Together with a Martin-Puplett spectrometer the set-up enables spectroscopic mapping of the transmittance of samples well below the diffraction limit. Spatial resolution down to about λ/40 at 2 wavenumbers (0.06 THz) is derived from the transmittance spectra of the near-field probes. The potential of the technique is exemplified by imaging biological samples. Strongly absorbing living leaves have been imaged in transmittance with a spatial resolution of 130 μm at about 12 wavenumbers (0.36 THz). The THz near-field images reveal distinct structural differences of leaves from different plants investigated. The technique presented also allows spectral imaging of bulky organic tissues. Human teeth samples of various thicknesses have been imaged between 2 and 20 wavenumbers (between 0.06 and 0.6 THz). Regions of enamel and dentin within tooth samples are spatially and spectrally resolved, and buried caries lesions are imaged through both the outer enamel and into the underlying dentin.

  1. Near-field study of magneto-optical samples: theoretical comparison of transversal and polar effects

    NASA Astrophysics Data System (ADS)

    Van Labeke, Daniel; Vial, A.; Barchiesi, Dominique

    1996-09-01

    The density of integration of magneto-optical devices is limited by diffraction of light. Recently some groups have proposed to use Near-Field Microscopy to overcome this limitation and some experiments have been performed both in transmission and reflection. In this paper we study theoretically magneto-optical effect in near-field. We consider a magneto-optical sample with details smaller than the wavelength. This sample is modelled as a multilayer rough structure. At least one layer has magneto-optical properties. The corrugation at the interfaces are very small compared to the optical wavelength. We do not consider the writing problem and the experiment is only modelled in the reading mode. Moreover, the magnetic properties are considered in the saturation regime. For this study we use an extension of the method that we used to describe near- field microscope with isotropic sample. The diffracted fields are determined in each layer by using a perturbative version of the Rayleigh method which leads to the resolution of a linear equation for each diffracted wave. The near- field above the sample is thus obtained by summing all the diffracted waves. We consider two geometries for the magnetization: polar effect where the magnetization is perpendicular to the sample and transversal effect where it is in the plane. We compare near-field images obtained in transmission and reflection by changing magnetization orientation. Comparisons with far-field results are also proposed.

  2. Electromagnetic Simulation of the Near-Field Distribution around a Wind Farm

    DOE PAGESBeta

    Yang, Shang-Te; Ling, Hao

    2013-01-01

    An efficienmore » t approach to compute the near-field distribution around and within a wind farm under plane wave excitation is proposed. To make the problem computationally tractable, several simplifying assumptions are made based on the geometry problem. By comparing the approximations against full-wave simulations at 500 MHz, it is shown that the assumptions do not introduce significant errors into the resulting near-field distribution. The near fields around a 3 × 3 wind farm are computed using the developed methodology at 150 MHz, 500 MHz, and 3 GHz. Both the multipath interference patterns and the forward shadows are predicted by the proposed method.« less

  3. Dual-channel near-field control by polarizations using isotropic and inhomogeneous metasurface

    NASA Astrophysics Data System (ADS)

    Wan, Xiang; Cai, Ben Geng; Li, Yun Bo; Cui, Tie Jun

    2015-11-01

    We propose a method for dual-channel near-field manipulations by designing isotropic but inhomogeneous metasurfaces. As example, we present a dual-channel near-field focusing metasurface device. When the device is driven by surface waves from different channels on the metasurface, the near fields will be focused at the same spatial point with different polarizations. Conversely, if a linearly polarized source is radiated at the spatial focal point, different channels will be evoked on the metasurface controlled by polarization. We fabricated and measured the metasurface device in the microwave frequency. Well agreements between the simulation and measurement results are observed. The proposed method exhibits great flexibility in controlling the surface waves and spatial waves simultaneously. It is expected that the proposed method and dual-channel device will facilitate the manipulation of near electromagnetic or optical waves in different frequency regimes.

  4. Improvement of infrared near-field spectrum by asymmetric interferometer configuration

    NASA Astrophysics Data System (ADS)

    Ikemoto, Yuka; Okamura, Hidekazu; Moriwaki, Taro; Suto, Hitoshi; Kinoshita, Toyohiko

    2015-08-01

    Infrared synchrotron radiation (IR-SR) is a highly brilliant white light source. We are developing an infrared near-field spectroscopy system with an IR-SR light source. The near-field spectroscopy system previously reported comprised an atomic force microscope (AFM) and a commercial Fourier transform infrared (FTIR) spectrometer. In the present study, the configuration of the FTIR interferometer has been modified to an asymmetric one. In the asymmetric interferometer, one beam split by a beamsplitter is focused onto the tip of an AFM probe, and the other beam goes to a movable mirror. The scattered light from the probe and the light reflected by the movable mirror interfere with each other. The near-field signal is extracted by a modulation method with an AFM oscillation frequency. The signal-to-noise ratio has been improved 6-fold and the signal-to-background ratio is improved 8-fold compared with those observed in the previous system.

  5. Near-Field Spectroscopy and Imaging of Subwavelength Plasmonic Terahertz Resonators

    DOE PAGESBeta

    Mitrofanov, Oleg; Khromova, Irina; Siday, Thomas; Thompson, Robert J.; Ponomarev, Andrey N.; Brener, Igal; Reno, John L.

    2016-04-22

    We describe the temporal evolution of the terahertz (THz) field leading to the excitation of plasmonic resonances in carbon microfibers. The field evolution is mapped in space and time for the 3/2 wavelength resonance using a subwavelength aperture THz near-field probe with an embedded THz photoconductive detector. The excitation of surface waves at the fiber tips leads to the formation of a standing wave along the fiber. Local THz time-domain spectroscopy at one of the standing wave crests shows a clear third-order resonance peak at 1.65 THz, well described by the Lorentz model. Lastly, this application of the subwavelength aperturemore » THz near-field microscopy for mode mapping and local spectroscopy demonstrates the potential of near-field methods for studies of subwavelength plasmonic THz resonators.« less

  6. Natural geochemical analogues of the near field of high-level nuclear waste repositories

    SciTech Connect

    Apps, J.A.

    1995-09-01

    United States practice has been to design high-level nuclear waste (HLW) geological repositories with waste densities sufficiently high that repository temperatures surrounding the waste will exceed 100{degrees}C and could reach 250{degrees}C. Basalt and devitrified vitroclastic tuff are among the host rocks considered for waste emplacement. Near-field repository thermal behavior and chemical alteration in such rocks is expected to be similar to that observed in many geothermal systems. Therefore, the predictive modeling required for performance assessment studies of the near field could be validated and calibrated using geothermal systems as natural analogues. Examples are given which demonstrate the need for refinement of the thermodynamic databases used in geochemical modeling of near-field natural analogues and the extent to which present models can predict conditions in geothermal fields.

  7. Sub-nanosecond time-resolved near-field scanning magneto-optical microscope.

    PubMed

    Rudge, J; Xu, H; Kolthammer, J; Hong, Y K; Choi, B C

    2015-02-01

    We report on the development of a new magnetic microscope, time-resolved near-field scanning magneto-optical microscope, which combines a near-field scanning optical microscope and magneto-optical contrast. By taking advantage of the high temporal resolution of time-resolved Kerr microscope and the sub-wavelength spatial resolution of a near-field microscope, we achieved a temporal resolution of ∼50 ps and a spatial resolution of <100 nm. In order to demonstrate the spatiotemporal magnetic imaging capability of this microscope, the magnetic field pulse induced gyrotropic vortex dynamics occurring in 1 μm diameter, 20 nm thick CoFeB circular disks has been investigated. The microscope provides sub-wavelength resolution magnetic images of the gyrotropic motion of the vortex core at a resonance frequency of ∼240 MHz. PMID:25725848

  8. Near-field visualization of plasmonic lenses: an overall analysis of characterization errors

    PubMed Central

    Wang, Jing; Xu, Zongwei; Fang, Fengzhou

    2015-01-01

    Summary Many factors influence the near-field visualization of plasmonic structures that are based on perforated elliptical slits. Here, characterization errors are experimentally analyzed in detail from both fabrication and measurement points of view. Some issues such as geometrical parameter, probe–sample surface interaction, misalignment, stigmation, and internal stress, have influence on the final near-field probing results. In comparison to the theoretical ideal case of near-field probing of the structures, numerical calculation is carried out on the basis of a finite-difference and time-domain (FDTD) algorithm so as to support the error analyses. The analyses performed on the basis of both theoretical calculation and experimental probing can provide a helpful reference for the researchers probing their plasmonic structures and nanophotonic devices. PMID:26665078

  9. Near Field Radiation Characteristics of Implantable Square Spiral Chip Inductor Antennas for Bio-Sensors

    NASA Technical Reports Server (NTRS)

    Nessel, James A.; Simons, Rainee N.; Miranda, Felix A.

    2007-01-01

    The near field radiation characteristics of implantable Square Spiral Chip Inductor Antennas (SSCIA) for Bio-Sensors have been measured. Our results indicate that the measured near field relative signal strength of these antennas agrees with simulated results and confirm that in the near field region the radiation field is fairly uniform in all directions. The effects of parameters such as ground-plane, number of turns and microstrip-gap width on the performance of the SSCIA are presented. Furthermore, the SSCIA antenna with serrated ground plane produce a broad radiation pattern, with a relative signal strength detectable at distances within the range of operation of hand-held devices for self-diagnosis.

  10. Dual-channel near-field control by polarizations using isotropic and inhomogeneous metasurface.

    PubMed

    Wan, Xiang; Cai, Ben Geng; Li, Yun Bo; Cui, Tie Jun

    2015-01-01

    We propose a method for dual-channel near-field manipulations by designing isotropic but inhomogeneous metasurfaces. As example, we present a dual-channel near-field focusing metasurface device. When the device is driven by surface waves from different channels on the metasurface, the near fields will be focused at the same spatial point with different polarizations. Conversely, if a linearly polarized source is radiated at the spatial focal point, different channels will be evoked on the metasurface controlled by polarization. We fabricated and measured the metasurface device in the microwave frequency. Well agreements between the simulation and measurement results are observed. The proposed method exhibits great flexibility in controlling the surface waves and spatial waves simultaneously. It is expected that the proposed method and dual-channel device will facilitate the manipulation of near electromagnetic or optical waves in different frequency regimes. PMID:26527420

  11. Dual-channel near-field control by polarizations using isotropic and inhomogeneous metasurface

    PubMed Central

    Wan, Xiang; Cai, Ben Geng; Li, Yun Bo; Cui, Tie Jun

    2015-01-01

    We propose a method for dual-channel near-field manipulations by designing isotropic but inhomogeneous metasurfaces. As example, we present a dual-channel near-field focusing metasurface device. When the device is driven by surface waves from different channels on the metasurface, the near fields will be focused at the same spatial point with different polarizations. Conversely, if a linearly polarized source is radiated at the spatial focal point, different channels will be evoked on the metasurface controlled by polarization. We fabricated and measured the metasurface device in the microwave frequency. Well agreements between the simulation and measurement results are observed. The proposed method exhibits great flexibility in controlling the surface waves and spatial waves simultaneously. It is expected that the proposed method and dual-channel device will facilitate the manipulation of near electromagnetic or optical waves in different frequency regimes. PMID:26527420

  12. Terahertz near-field microscopy with subwavelength spatial resolution based on photoconductive antennas.

    PubMed

    Bitzer, Andreas; Ortner, Alex; Walther, Markus

    2010-07-01

    Imaging and sensing applications based on pulsed terahertz radiation have opened new possibilities for scientific and industrial applications. Many exploit the unique features of the terahertz (THz) spectral region, where common packaging materials are transparent and many chemical compounds show characteristic absorptions. Because of their diffraction limit, THz far-field imaging techniques lack microscopic resolution and, if subwavelength features have to be resolved, near-field techniques are required. Here, we present a THz near-field microscopy approach based on photoconductive antennas as the THz emitter and as a near-field probe. Our system allows us to measure amplitude, phase, and polarization of the electric fields in the vicinity of a sample with a spatial resolution on the micrometer scale (approximately lambda/20). Using a dielectric (plant leaf) and a metallic structure (microwire) as examples, we demonstrate the capabilities of our approach. PMID:20648112

  13. Terahertz pulse propagation in the near field and the far field.

    PubMed

    Gürtler, A; Winnewisser, C; Helm, H; Jepsen, P U

    2000-01-01

    We present a detailed investigation of the propagation properties of beams of ultrashort terahertz (THz) pulses emitted from large-aperture (LA) antennas. The large area of the emitter is demonstrated to have substantial influence on the temporal pulse profile in both the near field and the far field. We perform a numerical analysis based on scalar and vectorial broadband diffraction theory and are able to distinguish between near-field and far-field contributions to the total THz signal. We find that the THz beam from a LA antenna propagates like a Gaussian beam and that the temporal profile of the THz pulse, measured in the near field, contains information about the temporal and spatial field distribution on the emitter surface, which is intrinsically connected to the carrier dynamics of the antenna substrate. As a result of pulse reshaping, focusing of the THz beam leads to a reduced relative pulse momentum, with implications in THz field-ionization experiments. PMID:10641841

  14. Near-field fluorescence imaging with 32 nm resolution based on microfabricated cantilevered probes

    NASA Astrophysics Data System (ADS)

    Eckert, Rolf; Freyland, J. Moritz; Gersen, Henkjan; Heinzelmann, Harry; Schürmann, Gregor; Noell, Wilfried; Staufer, Urs; de Rooij, Nico F.

    2000-12-01

    High-resolution near-field optical imaging with microfabricated probes is demonstrated. The probes are made from solid quartz tips fabricated at the end of silicon cantilevers and covered with a 60-nm-thick aluminum film. Transmission electron micrographs indicate a continuous aluminum layer at the tip apex. A specially designed instrument combines the advantages of near-field optical and beam-deflection force microscopy. Near-field optical data of latex bead projection patterns in transmission and of single fluorophores have been obtained in constant-height imaging mode. An artifact-free optical resolution of 31.7±3.6 nm has been deduced from full width at half maximum values of single molecule images.

  15. Nonoptically probing near-field microscopy for the observation of biological living specimens

    NASA Astrophysics Data System (ADS)

    Kawata, Yoshimasa; Murakami, Manabu; Egami, Chikara; Sugihara, Okihiro; Okamoto, Naomichi; Tsuchimori, Masaaki; Watanabe, Osamu; Nakamura, Osamu

    2001-04-01

    We present the observation of living specimens with subwavelength resolution by using the nonoptically probing near-field microscopy we have developed recently. In the near-field microscope, the optical field distributions near the specimens are recorded as the surface topography of a photosensitive film, and the topographical distributions are readout with an atomic-force microscopy. Since the near-field microscope does not require the scanning of a probe tip for illumination or detection or scattering of light, it is possible to observe moving biological specimens and fast phenomena. We demonstrate the observation of a moving paramecium and euglena gracilis with subwavelength resolution. The observation of the nucleus inside a euglena cell was also demonstrated.

  16. An evaluation of near-field host rock temperatures for a spent fuel repository

    SciTech Connect

    Altenhofen, M.K.; Lowery, P.S.

    1988-11-01

    A repository heat transfer analysis has been performed by the Pacific Northwest Laboratory (PNL) for the US Department of Energy's Performance Assessment Scientific Support Program. The objective of this study was to evaluate the near-field thermal environmental conditions for a spent fuel repository system. A spent fuel logistics analysis was performed using a waste management system simulation model, WASTES-II, to evaluate the thermal characteristics of spent fuel received at the repository. A repository-scale thermal analysis was performed using a finite difference heat transfer code, TEMPEST, to evaluate the near-field host rock temperature. The calculated temporal and spatial distributions of near-field host rock temperatures provide input to the repository source term model in evaluations of engineered barrier system performance. 9 refs., 10 figs., 2 tabs.

  17. Neptunium Solubility in the Near-Field Environment of A Proposed Yucca Mountain Repository

    SciTech Connect

    D.C. Sassani

    2004-05-14

    For representing the source-term of a proposed repository at Yucca Mountain, NV, total system performance assessment models evaluate the disequilibrium degradation of the waste forms to capture a bounding rate for radionuclide source-term availability and use solubility constraints that are more representative of longer-term, equilibrium processes to limit radionuclide mass transport from the source-term. These solubility limits capture precipitation processes occurring either as the waste forms alter, or in the near-field environment as chemical conditions evolve. A number of alternative models for solubility controls on dissolved neptunium concentrations have been evaluated. These include idealized models based on precipitation of neptunium as separate oxide minerals and more complex considerations of trace amounts of neptunium being incorporated into the secondary uranyl phases from waste form alteration. Thermodynamic models for neptunium under oxidizing conditions indicate that tetravalent neptunium (NpO{sub 2}) solids are more stable relative to pentavalent (Np{sub 2}O{sub 5}) phases, and thereby set lower dissolved concentrations of neptunyl species. Data on solids and solutions from slow flow through (dripping) tests on spent fuel grains indicate that neptunium is tetravalent in the spent fuel and that over {approx}9 years the neptunium concentrations are near to or below calculated NpO{sub 2} solubility. The possibility of kinetic rate limitations to NpO{sub 2} precipitation has led to temperature-dependent studies of NpO{sub 2} precipitation kinetics and solubility to reduce uncertainties and confirm application of the model.

  18. Three-dimensional radar imaging techniques and systems for near-field applications

    NASA Astrophysics Data System (ADS)

    Sheen, David M.; Hall, Thomas E.; McMakin, Douglas L.; Jones, A. Mark; Tedeschi, Jonathan R.

    2016-05-01

    The Pacific Northwest National Laboratory has developed three-dimensional holographic (synthetic aperture) radar imaging techniques and systems for a wide variety of near-field applications. These applications include radar crosssection (RCS) imaging, personnel screening, standoff concealed weapon detection, concealed threat detection, throughbarrier imaging, ground penetrating radar (GPR), and non-destructive evaluation (NDE). Sequentially-switched linear arrays are used for many of these systems to enable high-speed data acquisition and 3-D imaging. In this paper, the techniques and systems will be described along with imaging results that demonstrate the utility of near-field 3-D radar imaging for these compelling applications.

  19. Graphene-assisted near-field radiative heat transfer between corrugated polar materials

    SciTech Connect

    Liu, X. L.; Zhang, Z. M.

    2014-06-23

    Graphene has attracted great attention in nanoelectronics, optics, and energy harvesting. Here, the near-field radiative heat transfer between graphene-covered corrugated silica is investigated based on the exact scattering theory. It is found that graphene can improve the radiative heat flux between silica gratings by more than one order of magnitude and alleviate the performance sensitivity to lateral shift. The underlying mechanism is mainly attributed to the improved photon tunneling of modes away from phonon resonances. Besides, coating with graphene leads to nonlocal radiative transfer that breaks Derjaguin's proximity approximation and enables corrugated silica to outperform bulk silica in near-field radiation.

  20. Imaging of green fluorescent protein in live plant by scanning near-field optical microscopy

    NASA Astrophysics Data System (ADS)

    Xu, Jianhua; Chen, Tao; Sun, Jialin; Guo, Jihua; Zhao, Jun

    2002-04-01

    An auxin/IAA induced in vivo green fluorescent protein (GFP) in a living plant Arabidopsis root has been studied by a scanning near-field microscope in transmission mode. The promising near-field images of the inducible GFPs at sub- surface of a plant cell suggest that they may locate proximity to the cell wall, i.e. both sides of and in the cytoplasm membrane. The clear and faint fluorescent spots with 1-3 micrometers showed that the proteins localized nearer and farther to the cell wall, respectively. All GFP molecules gathered together in a cell, and no individual GFP was observed in the experiment.

  1. Near field and altered zone environmental report Volume I: technical bases for EBS design

    SciTech Connect

    Wilder, D. G., LLNL

    1997-08-01

    This report presents an updated summary of results for the waste package (WP) and engineered barrier system (EBS) evaluations, including materials testing, waste-form characterization, EBS performance assessments, and near-field environment (NFE) characterization. Materials testing, design criteria and concept development, and waste-form characterization all require an understanding of the environmental conditions that will interact with the WP and EBS. The Near-Field Environment Report (NFER) was identified in the Waste Package Plan (WPP) (Harrison- Giesler, 1991) as the formal means for transmitting and documenting this information.

  2. Near field thermal memory based on radiative phase bistability of VO2

    NASA Astrophysics Data System (ADS)

    Dyakov, S. A.; Dai, J.; Yan, M.; Qiu, M.

    2015-08-01

    We report the concept of a near-field memory device based on the radiative bistability effect in the system of two closely separated parallel plates of SiO2 and VO2 which exchange heat by thermal radiation in vacuum. We demonstrate that the VO2 plate, having metal-insulator transition at 340 K, has two thermodynamical steady-states. One can switch between the states using an external laser impulse. We show that due to near-field photon tunneling between the plates, the switching time is found to be only 5 ms which is several orders lower than in case of far field.

  3. Millimeter-wave near-field imaging with bow-tie antennas.

    PubMed

    Omarouayache, Rachid; Payet, Pierre; Raoult, Jérémy; Chusseau, Laurent

    2015-05-01

    A near-field reflectometry experiment operating at 60 GHz is built in view of material and circuit inspection. Experiments are always obtained in constant height mode of operation. The bow-tie near-field probe acts mostly as a linearly-polarized electric dipole and allows strongly subwavelength resolution of ≈ λ/130. Its interaction with sample is shown polarization dependent and sensitive to both the local topography and the local dielectric constant or metal conductivity. Resonant and non-resonant probes are both evaluated. PMID:25969302

  4. Demonstration of strong near-field radiative heat transfer between integrated nanostructures.

    PubMed

    St-Gelais, Raphael; Guha, Biswajeet; Zhu, Linxiao; Fan, Shanhui; Lipson, Michal

    2014-12-10

    Near-field heat transfer recently attracted growing interest but was demonstrated experimentally only in macroscopic systems. However, several projected applications would be relevant mostly in integrated nanostructures. Here we demonstrate a platform for near-field heat transfer on-chip and show that it can be the dominant thermal transport mechanism between integrated nanostructures, overcoming background substrate conduction and the far-field limit (by factors 8 and 7, respectively). Our approach could enable the development of active thermal control devices such as thermal rectifiers and transistors. PMID:25420115

  5. Shape matters: Near-field fluid mechanics dominate the collective motions of ellipsoidal squirmers.

    PubMed

    Kyoya, K; Matsunaga, D; Imai, Y; Omori, T; Ishikawa, T

    2015-12-01

    Microswimmers show a variety of collective motions. Despite extensive study, questions remain regarding the role of near-field fluid mechanics in collective motion. In this paper, we describe precisely the Stokes flow around hydrodynamically interacting ellipsoidal squirmers in a monolayer suspension. The results showed that various collective motions, such as ordering, aggregation, and whirls, are dominated by the swimming mode and the aspect ratio. The collective motions are mainly induced by near-field fluid mechanics, despite Stokes flow propagation over a long range. These results emphasize the importance of particle shape in collective motion. PMID:26764823

  6. Near-field VLBI and its applications to Space Science Missions.

    NASA Astrophysics Data System (ADS)

    Cimo, G.; Molera Calves, G.; Pogrebenko, S. V.; Duev, D. A.; Bocanegra Bohamon, T.; Gurvits, L. I.

    2014-04-01

    Near-field Very Long Baseline Interferometry (VLBI) is a radio astronomical technique that, when applied to observations of spacecraft, provides unique insights on those areas of space mission scientific return, which require precise determination of lateral position of spacecraft on the celestial sphere. The Planetary Radio Interferometry and Doppler Experiment (PRIDE) exploits near-field VLBI for accurate estimation of the state-vector of a spacecraft using arrays of radio telescopes available around the world. We will present new results of recent experiments with current ESA's missions (Venus Express, Mars Express, Gaia) while showing the numerous implementations of the PRIDE technique.

  7. Near-field magnetophotoluminescence spectroscopy of composition fluctuations in InGaAsN.

    SciTech Connect

    Mintariov, A. M.; Kosel, T. H.; Merz, J. L.; Blagnov, P. A.; Vlasov, A. S.; Ustinov, V. M.; Cook, R. E.; Materials Science Division; Univ. of Notre Dame; Ioffe Physico-Technical Inst.

    2001-12-31

    The localization of excitons on quantum-dot-like compositional fluctuations has been observed in temperature-dependent near-field magnetophotoluminescence spectra of InGaAsN. Localization is driven by the giant bowing parameter of these alloys and manifests itself by the appearance of ultranarrow lines (half-width <1 meV) at temperatures below 70 K. We show how near-field optical scanning microscopy can be used for the estimation of the size, density, and nitrogen excess of individual compositional fluctuations (clusters), thus revealing random versus phase-separation effects in the distribution of nitrogen.

  8. Near-field thermal radiation between hyperbolic metamaterials: Graphite and carbon nanotubes

    SciTech Connect

    Liu, X. L.; Zhang, R. Z.; Zhang, Z. M.

    2013-11-18

    The near-field radiative heat transfer for two hyperbolic metamaterials, namely, graphite and vertically aligned carbon nanotubes (CNTs), is investigated. Graphite is a naturally existing uniaxial medium, while CNT arrays can be modeled as an effective anisotropic medium. Different hyperbolic modes can be separately supported by these materials in certain infrared regions, resulting in a strong enhancement in near-field heat transfer. It is predicted that the heat flux between two CNT arrays can exceed that between SiC plates at any vacuum gap distance and is about 10 times higher with a 10 nm gap.

  9. Near-field studies of microwave three-dimensional photonic crystals with waveguides.

    PubMed

    Liu, Rong-Juan; Li, Zhi-Yuan; Zhou, Fei; Zhang, Dao-Zhong

    2007-11-12

    By utilizing a vector network analyzer, the field distributions on the surface of a three-dimensional woodpile photonic crystal with a straight waveguide or a bend waveguide buried under the surface were measured in the microwave regime. The information of field profile and propagation characteristics of the guided modes can be successfully extracted from the surface near-field measurement. This work indicates that the near-field detection can become a promising means for experimental characterization of three-dimensional photonic crystal devices in supplement to the usual transmission spectrum measurement. PMID:19550839

  10. Alterations of single molecule fluorescence lifetimes in near-field optical microscopy

    SciTech Connect

    Ambrose, W.P.; Goodwin, P.M.; Keller, R.A.; Martin, J.C. )

    1994-07-15

    Fluorescence lifetimes of single Rhodamine 6G molecules on silica surfaces were measured with pulsed laser excitation, time-correlated single photon counting, and near-field scanning optical microscopy (NSOM). The fluorescence lifetime varies with the position of a molecule relative to a near-field probe. Qualitative features of lifetime decreases are consistent with molecular excited state quenching effects near metal surfaces. The technique of NSOM provides a means of altering the environment of a single fluorescent molecule and its decay kinetics in a repeatable fashion.

  11. Near-field scanning microwave microscopy of few-layer graphene.

    SciTech Connect

    Kalugin, Nikolai G.; Gonzales, Edward; Kalichava, Irakli; Gin, Aaron V.; Wickey, Lee; Del Barga, Christopher; Talanov, Vladimir V.; Shaner, Eric Arthur

    2010-08-01

    Near-field microwave microscopy can be used as an alternative to atomic-force microscopy or Raman microscopy in determination of graphene thickness. We evaluated the values of AC impedance for few layer graphene. The impedance of mono and few-layer graphene at 4GHz was found predominantly active. Near-field microwave microscopy allows simultaneous imaging of location, geometry, thickness, and distribution of electrical properties of graphene without device fabrication. Our results may be useful for design of future graphene-based microwave devices.

  12. Cancer cell imaging by stable wet near-field scanning optical microscope with resonance tracking method

    NASA Astrophysics Data System (ADS)

    Park, Kyoung-Duck; Park, Doo Jae; Jeong, Mun Seok; Choi, Geun Chang; Lee, Seung Gol; Byeon, Clare Chisu; Choi, Soo Bong

    2014-05-01

    We report on a successful topographical and optical imaging of various cancer cells in liquid and in air by using a stable wet near-field scanning optical microscope that utilizes a resonance tracking method. We observed a clear dehydration which gives rise to a decrease in the cell volume down to 51%. In addition, a micro-ball lens effect due to the round-shaped young cancer cells was observed from near-field imaging, where the refractive index of young cancer cells was deduced.

  13. Method of processing materials using an inductively coupled plasma

    DOEpatents

    Hull, Donald E.; Bieniewski, Thomas M.

    1990-01-01

    A method for making fine power using an inductively coupled plasma. The method provides a gas-free environment, since the plasma is formed without using a gas. The starting material used in the method is in solid form.

  14. Small spatial and fast temporal ionosphere-magnetosphere coupling processes

    NASA Astrophysics Data System (ADS)

    Zhu, Hua

    2000-09-01

    I have developed a two-dimensional, three-fluid model (electrons, ions and neutrals) to simulate small-scale magnetosphere-ionosphere coupling processes. The code includes ionization and recombination processes, the Hall term in Ohm's law, and various heat sources in the energy equations. The electro-dynamic response and the evolution of the collision frequencies are treated self- consistently in a height resolved ionosphere. The model allows for the propagation of Alfvén waves. The simulation is particularly suited for fast temporal variations and small spatial scale ionospheric structures associated with filamentary aurora and ionospheric heating experiments (e.g. HAARP). I have investigated the evolution of field-aligned currents in the magnetosphere-ionosphere system and found several notable effects-ion heating due to plasma- neutral friction, electron heating resulting from energetic particle precipitation and ohmic dissipation by strong field-aligned currents. The simulation of plasma. heating in the ionosphere is motivated by a specific auroral event that was simultaneously observed with optical and radar instruments. The results indicate that a consistent explanation of this event requires ohmic heating of electrons in a strong field-aligned electric current layer. They suggest strongly that the observed sequence of events can be explained only if spatial structure is present in the ionosphere so that it requires at least a two-dimensional model. Electron heating in strong field-aligned currents also provides a mechanism to deposit energy in the F-region of ionosphere and thus can explain the formation of tall auroral arcs. The simulation of the formation of field-aligned currents shows a strong plasma density depletion in the region of downward field-aligned current layer. The depletion is due to the divergent flow of the plasma. Similarly, the plasma density increases in the region of upward field- aligned current because of the convergent plasma motion

  15. ‘Squeezing’ near-field thermal emission for ultra-efficient high-power thermophotovoltaic conversion

    PubMed Central

    Karalis, Aristeidis; Joannopoulos, J. D.

    2016-01-01

    We numerically demonstrate near-field planar ThermoPhotoVoltaic systems with very high efficiency and output power, at large vacuum gaps. Example performances include: at 1200 °K emitter temperature, output power density 2 W/cm2 with ~47% efficiency at 300 nm vacuum gap; at 2100 °K, 24 W/cm2 with ~57% efficiency at 200 nm gap; and, at 3000 °K, 115 W/cm2 with ~61% efficiency at 140 nm gap. Key to this striking performance is a novel photonic design forcing the emitter and cell single modes to cros resonantly couple and impedance-match just above the semiconductor bandgap, creating there a ‘squeezed’ narrowband near-field emission spectrum. Specifically, we employ surface-plasmon-polariton thermal emitters and silver-backed semiconductor-thin-film photovoltaic cells. The emitter planar plasmonic nature allows for high-power and stable high-temperature operation. Our simulations include modeling of free-carrier absorption in both cell electrodes and temperature dependence of the emitter properties. At high temperatures, the efficiency enhancement via resonant mode cross-coupling and matching can be extended to even higher power, by appropriately patterning the silver back electrode to enforce also an absorber effective surface-plasmon-polariton mode. Our proposed designs can therefore lead the way for mass-producible and low-cost ThermoPhotoVoltaic micro-generators and solar cells. PMID:27363522

  16. ‘Squeezing’ near-field thermal emission for ultra-efficient high-power thermophotovoltaic conversion

    NASA Astrophysics Data System (ADS)

    Karalis, Aristeidis; Joannopoulos, J. D.

    2016-07-01

    We numerically demonstrate near-field planar ThermoPhotoVoltaic systems with very high efficiency and output power, at large vacuum gaps. Example performances include: at 1200 °K emitter temperature, output power density 2 W/cm2 with ~47% efficiency at 300 nm vacuum gap; at 2100 °K, 24 W/cm2 with ~57% efficiency at 200 nm gap; and, at 3000 °K, 115 W/cm2 with ~61% efficiency at 140 nm gap. Key to this striking performance is a novel photonic design forcing the emitter and cell single modes to cros resonantly couple and impedance-match just above the semiconductor bandgap, creating there a ‘squeezed’ narrowband near-field emission spectrum. Specifically, we employ surface-plasmon-polariton thermal emitters and silver-backed semiconductor-thin-film photovoltaic cells. The emitter planar plasmonic nature allows for high-power and stable high-temperature operation. Our simulations include modeling of free-carrier absorption in both cell electrodes and temperature dependence of the emitter properties. At high temperatures, the efficiency enhancement via resonant mode cross-coupling and matching can be extended to even higher power, by appropriately patterning the silver back electrode to enforce also an absorber effective surface-plasmon-polariton mode. Our proposed designs can therefore lead the way for mass-producible and low-cost ThermoPhotoVoltaic micro-generators and solar cells.

  17. COUPLING

    DOEpatents

    Hawke, B.C.

    1963-02-26

    This patent relates to a releasable coupling connecting a control rod to a control rod drive. This remotely operable coupling mechanism can connect two elements which are laterally and angviarly misaligned, and provides a means for sensing the locked condition of the elements. The coupling utilizes a spherical bayonet joint which is locked against rotation by a ball detent lock. (AEC)

  18. Photoplastic near-field optical probe with sub-100 nm aperture made by replication from a nanomould.

    PubMed

    Kim, G M; Kim, B J; Ten Have, E S; Segerink, F; Van Hulst, N F; Brugger, J

    2003-03-01

    Polymers have the ability to conform to surface contours down to a few nanometres. We studied the filling of transparent epoxy-type EPON SU-8 into nanoscale apertures made in a thin metal film as a new method for polymer/metal near-field optical structures. Mould replica processes combining silicon micromachining with the photo-curable SU-8 offer great potential for low-cost nanostructure fabrication. In addition to offering a route for mass production, the transparent pyramidal probes are expected to improve light transmission thanks to a wider geometry near the aperture. By combining silicon MEMS, mould geometry tuning by oxidation, anti-adhesion coating by self-assembled monolayer and mechanical release steps, we propose an advanced method for near-field optical probe fabrication. The major improvement is the possibility to fabricate nanoscale apertures directly on wafer scale during the microfabrication process and not on free-standing tips. Optical measurements were performed with the fabricated probes. The full width half maximum after a Gaussian fit of the intensity profile indicates a lateral optical resolution of approximately 60 nm. PMID:12641773

  19. Client Discourses on the Process of Seeking Same-Sex Couple Counselling

    ERIC Educational Resources Information Center

    Grove, Jan; Peel, Elizabeth; Owen-Pugh, Valerie

    2013-01-01

    How same-sex couples manage the process of seeking help for their relationships is an under-researched area. Twelve semi-structured interviews were conducted with 16 people who had engaged in same-sex couple counselling, and were analysed using discourse analysis. The ways in which the couples positioned themselves as part of a "minority…

  20. Efficiency and Usability of a Near Field Communication-Enabled Tablet for Medication Administration

    PubMed Central

    Neri, Pamela M; Robertson, Alexandra; McEvoy, Dustin; Dinsmore, Michael; Sweet, Micheal; Bane, Anne; Takhar, Sukhjit S; Miles, Stephen

    2014-01-01

    Background Barcode-based technology coupled with the electronic medication administration record (e-MAR) reduces medication errors and potential adverse drug events (ADEs). However, many current barcode-enabled medication administration (BCMA) systems are difficult to maneuver and often require multiple barcode scans. We developed a prototype, next generation near field communication-enabled medication administration (NFCMA) system using a tablet. Objective We compared the efficiency and usability of the prototype NFCMA system with the traditional BCMA system. Methods We used a mixed-methods design using a randomized observational cross-over study, a survey, and one-on-one interviews to compare the prototype NFCMA system with a traditional BCMA system. The study took place at an academic medical simulation center. Twenty nurses with BCMA experience participated in two simulated patient medication administration scenarios: one using the BCMA system, and the other using the prototype NFCMA system. We collected overall scenario completion time and number of medication scanning attempts per scenario, and compared those using paired t tests. We also collected participant feedback on the prototype NFCMA system using the modified International Business Machines (IBM) Post-Study System Usability Questionnaire (PSSUQ) and a semistructured interview. We performed descriptive statistics on participant characteristics and responses to the IBM PSSUQ. Interview data was analyzed using content analysis with a qualitative description approach to review and categorize feedback from participants. Results Mean total time to complete the scenarios using the NFCMA and the BCMA systems was 202 seconds and 182 seconds, respectively (P=.09). Mean scan attempts with the NFCMA was 7.6 attempts compared with 6.5 attempts with the BCMA system (P=.12). In the usability survey, 95% (19/20) of participants agreed that the prototype NFCMA system was easy to use and easy to learn, with a pleasant

  1. RADIATION EFFECTS ON MATERIALS IN THE NEAR-FIELD OF NUCLEAR WASTE REPOSITORY

    EPA Science Inventory

    Successful, demonstrated containment of radionuclides in the near-field can greatly reduce the complexity of the performance assessment analysis of a geologic repository. The chemical durability of the waste form, the corrosion rate of the canister, and the physical and chemical ...

  2. Harmonic demodulation and minimum enhancement factors in field-enhanced near-field optical microscopy.

    PubMed

    Scarpettini, A F; Bragas, A V

    2015-01-01

    Field-enhanced scanning optical microscopy relies on the design and fabrication of plasmonic probes which had to provide optical and chemical contrast at the nanoscale. In order to do so, the scattering containing the near-field information recorded in a field-enhanced scanning optical microscopy experiment, has to surpass the background light, always present due to multiple interferences between the macroscopic probe and sample. In this work, we show that when the probe-sample distance is modulated with very low amplitude, the higher the harmonic demodulation is, the better the ratio between the near-field signal and the interferometric background results. The choice of working at a given n harmonic is dictated by the experiment when the signal at the n + 1 harmonic goes below the experimental noise. We demonstrate that the optical contrast comes from the nth derivative of the near-field scattering, amplified by the interferometric background. By modelling the far and near field we calculate the probe-sample approach curves, which fit very well the experimental ones. After taking a great amount of experimental data for different probes and samples, we conclude with a table of the minimum enhancement factors needed to have optical contrast with field-enhanced scanning optical microscopy. PMID:25231792

  3. Near-field and far-field goniophotometry of focused LED arrays

    NASA Astrophysics Data System (ADS)

    Jacobs, Valéry A.; Forment, Stefaan; Rombauts, Patrick; Hanselaer, Peter

    2014-05-01

    Luminaires are conventionally modeled using a far-field representation. To calculate this representation, a photometer revolves a light source at fixed distance and illuminances are measured in a set of angular directions. Using the inversesquare- law, the far-field intensity, also termed luminous intensity distribution is then calculated. For Lambertian sources, the far-field starts from a distance of five times the maximal dimension of a light source; which is called the limiting photometric distance. The advent of luminaires composed of LED arrays with narrow beams have shown that this limit is no longer valid and far larger distances (up to 15 times the maximal diameter) are suggested by the lighting community. This problem is even more outspoken when the individual LEDs are focused at close distance, as in e.g. surgical luminaires. To overcome these problems, we exploit the use of a near-field representation to describe an array of two narrow-beam LEDs focused at close distance. For such a test source, this paper shows how a near-field luminance goniometer is able to construct ray-data. Ray files can be used to calculate a near-field representation and far-field representation of a light source. These measurements are validated by a theoretical derivation of the intensity of an array, using a simple analytical model to describe the emission of the individual LEDs. This near-field approach makes discussions to determine the far-field photometric distance superfluous.

  4. On the near field mean flow structure of transverse jets issuing into a supersonic freestream

    NASA Astrophysics Data System (ADS)

    Dickmann, Dean Anthony

    The near field mean flow structure of transverse jets issuing from a surface into supersonic crossflow is examined using numerical methods and separation topology. The Navier-Stokes solver Falcon, developed at Lockheed Martin, was used to simulate the interaction between the jet and freestream over a flat plate and a generic missile body. The near field flow structure included a lambda bow shock upstream of the jet interacting with the approaching boundary layer that forms a pair of horseshoe vortices while another lambda-structure closer to the jet formed a second pair of horseshoe vortices. As the jet was turned downstream by the crossflow, the so-called barrel shock terminates in a Mach disk while vortices formed within the jet plume. Downstream of the jet exit, new flow structure was identified in the form of three pairs of vortices. Horn, near field and far field wake vortices were present downstream of the jet as well as a series of compression waves resulting in a gradual pressure rise downstream of the jet overexpansion. The wave formations and the vortices formed from them affected separation topology, performance parameters and amplification coefficients. The current understanding of the flow structure in the near field of a transverse jet in supersonic flow must be amended to include these newly identified vortices and compression waves.

  5. A New Method for Analyzing Near-Field Faraday Probe Data in Hall Thrusters

    NASA Technical Reports Server (NTRS)

    Huang, Wensheng; Shastry, Rohit; Herman, Daniel A.; Soulas, George C.; Kamhawi, Hani

    2013-01-01

    This paper presents a new method for analyzing near-field Faraday probe data obtained from Hall thrusters. Traditional methods spawned from far-field Faraday probe analysis rely on assumptions that are not applicable to near-field Faraday probe data. In particular, arbitrary choices for the point of origin and limits of integration have made interpretation of the results difficult. The new method, called iterative pathfinding, uses the evolution of the near-field plume with distance to provide feedback for determining the location of the point of origin. Although still susceptible to the choice of integration limits, this method presents a systematic approach to determining the origin point for calculating the divergence angle. The iterative pathfinding method is applied to near-field Faraday probe data taken in a previous study from the NASA-300M and NASA-457Mv2 Hall thrusters. Since these two thrusters use centrally mounted cathodes, the current density associated with the cathode plume is removed before applying iterative pathfinding. A procedure is presented for removing the cathode plume. The results of the analysis are compared to far-field probe analysis results. This paper ends with checks on the validity of the new method and discussions on the implications of the results.

  6. Near-field dispersal modeling for liquid fuel-air explosives

    SciTech Connect

    Gardner, D.R.

    1990-07-01

    The near-field, explosive dispersal of a liquid into air has been explored using a combination of analytical and numerical models. The near-field flow regime is transient, existing only as long as the explosive forces produced by the detonation of the burster charge dominate or are approximately equal in magnitude to the aerodynamic drag forces on the liquid. The near-field model provides reasonable initial conditions for the far-field model, which is described in a separate report. The near-field model consists of the CTH hydrodynamics code and a film instability model. In particular, the CTH hydrodynamics code is used to provide initial temperature, pressure, and velocity fields, and bulk material distribution for the far-field model. The film instability model is a linear stability model for a radially expanding fluid film, and is used to provide a lower bound on the breakup time and an upper and lower bound on the initial average drop diameter for the liquid following breakup. Predictions of the liquid breakup time and the initial arithmetic average drop diameter from the model compare favorably with the sparse experimental data. 26 refs., 20 figs., 8 tabs.

  7. Near-field imaging and nano-Fourier-transform infrared spectroscopy using broadband synchrotron radiation.

    PubMed

    Hermann, Peter; Hoehl, Arne; Patoka, Piotr; Huth, Florian; Rühl, Eckart; Ulm, Gerhard

    2013-02-11

    We demonstrate scanning near-field optical microscopy with a spatial resolution below 100 nm by using low intensity broadband synchrotron radiation in the IR regime. The use of such a broadband radiation source opens up the possibility to perform nano-Fourier-transform infrared spectroscopy over a wide spectral range. PMID:23481749

  8. Electroless silver plating for metallization of near-field optical fiber probes

    NASA Astrophysics Data System (ADS)

    Li, Chang'an; Xu, Lina; Gu, Ning

    2007-10-01

    By using mercaptopropyltrimethoxysilane (MPTS) self-assembled monolayers (SAMs), electroless silver plating is developed for the metallization of near-field optical fiber probes. This method has the advantages of controllability, no pinholes, convenience, low cost, and smooth tip surface. The metallized probes are characterized by optical microscopy, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDXS).

  9. A MEMS Device Capable of Measuring Near-Field Thermal Radiation between Membranes

    PubMed Central

    Feng, Chong; Tang, Zhenan; Yu, Jun; Sun, Changyu

    2013-01-01

    For sensors constructed by freestanding membranes, when the gap between a freestanding membrane and the substrate or between membranes is at micron scale, the effects of near-field radiative heat transfer on the sensors' thermal performance should be considered during sensor design. The radiative heat flux is transferred from a membrane to a plane or from a membrane to a membrane. In the current study of the near-field thermal radiation, the scanning probe technology has difficulty in making a membrane separated at micron scale parallel to a plane or another membrane. A novel MEMS (micro electromechanical system) device was developed by sacrificial layer technique in this work to realize a double parallel freestanding membrane structure. Each freestanding membrane has a platinum thin-film resistor and the distance between the two membranes is 1 μm. After evaluating the electrical and thermal characteristics of the lower freestanding membrane,experimental measurements of near-field radiative heat transfer between the lower membrane and the upper membrane were carried out by setting the lower membrane as a heat emitter and the upper membrane as a heat receiver. The near-field radiative heat transfer between the two membranes was validated by finding a larger-than-blackbody radiative heat transfer based on the experimental data. PMID:23385413

  10. A New Method for Analyzing Near-Field Faraday Probe Data in Hall Thrusters

    NASA Technical Reports Server (NTRS)

    Huang, Wensheng; Shastry, Rohit; Herman, Daniel A.; Soulas, George C.; Kamhawi, Hani

    2013-01-01

    This paper presents a new method for analyzing near-field Faraday probe data obtained from Hall thrusters. Traditional methods spawned from far-field Faraday probe analysis rely on assumptions that are not applicable to near-field Faraday probe data. In particular, arbitrary choices for the point of origin and limits of integration have made interpretation of the results difficult. The new method, called iterative pathfinding, uses the evolution of the near-field plume with distance to provide feedback for determining the location of the point of origin. Although still susceptible to the choice of integration limits, this method presents a systematic approach to determining the origin point for calculating the divergence angle. The iterative pathfinding method is applied to near-field Faraday probe data taken in a previous study from the NASA-300M and NASA-457Mv2 Hall thrusters. Since these two thrusters use centrally mounted cathodes the current density associated with the cathode plume is removed before applying iterative pathfinding. A procedure is presented for removing the cathode plume. The results of the analysis are compared to far-field probe analysis results. This paper ends with checks on the validity of the new method and discussions on the implications of the results.

  11. Multi-band near-field radiative heat transfer between two anisotropic fishnet metamaterials

    NASA Astrophysics Data System (ADS)

    Bai, Yang; Jiang, Yongyuan; Liu, Linhua

    2015-06-01

    We study the near-field radiative heat transfer between two metal-insulator-metal sandwiched-like fishnet metamaterials (FMMs) by fluctuation electrodynamics. Results show that multi-band heat flux between the fishnet metamaterials is achieved, which is attributed to the thermally excited surface modes within the FMM. Apart from the electric response mode of the near-field heat flux, magnetic modes are also existed, which are related with the excitations of the surface plasmon polaritons (SPPs) propagating on the outer surface of metal (external SPPs) and along the inner metal-dielectric interface (internal SPPs). Moreover, we show that the electromagnetic parameters of this anisotropic fishnet metamaterial depend on the angles θ of the incident light when heating the fishnet metamaterial, and thus the overall effect of the anisotropic FMM parameters is considered to predict the near-field radiative heat transfer. Different external-SPPs and internal-SPPs modes are excited at different frequencies which is attributed to the anisotropic electromagnetic response of FMM, which open new frequency channels of the near-field radiative heat transfer. This kind of anisotropic metamaterial should assist in thermal management in nanoscale.

  12. Three-dimensional mapping of optical near field of a nanoscale bowtie antenna.

    PubMed

    Guo, Rui; Kinzel, Edward C; Li, Yan; Uppuluri, Sreemanth M; Raman, Arvind; Xu, Xianfan

    2010-03-01

    Ridge nanoscale aperture antennas have been shown to be a high transmission nanoscale light source. They provide a small, polarization-dependent near-field optical spot with much higher transmission efficiency than circularly-shaped apertures with similar field confinement. This provides significant motivations to understand the electromagnetic fields in the immediate proximity to the apertures. This paper describes an experimental three-dimensional optical near-field mapping of a bowtie nano-aperture. The measurements are performed using a home-built near-field scanning optical microscopy (NSOM) system. An aluminum coated Si(3)N(4) probe with a 150 nm hole at the tip is used to collect optical signals. Both contact and constant-height scan (CHS) modes are used to measure the optical intensity at different longitudinal distances. A force-displacement curve is used to determine the tip-sample separation distance allowing the optical intensities to be mapped at distances as small as 50 nm and up to micrometer level. The experimental results also demonstrate the polarization dependence of the transmission through the bowtie aperture. Numerical simulations are also performed to compute the aperture's electromagnetic near-field distribution and are shown to agree with the experimental results. PMID:20389507

  13. Near-Field Radiation Between Graphene-Covered Carbon Nanotube Arrays

    NASA Astrophysics Data System (ADS)

    Zhang, Richard; Liu, Xianglei; Zhang, Zhuomin; Nanoscale Thermal Radiation Laboratory Team

    2015-03-01

    It has been shown that at nanometer gap distances, or the near-field, thermal radiation is enhanced over blackbody between hyperbolic metamaterials. It was shown that vertically aligned carbon nanotube (VACNT) arrays in the near-field demonstrate exceptional enhancement. In this study, graphene is covered on the surfaces of two semi-infinite VACNT arrays separated by a sub-micron vacuum gap. Doped graphene (μ >= 0.3 eV) is found to improve photon tunneling in a broad hyperbolic frequency range, due to the interaction with graphene-graphene surface plasmons. Increasing doping that shifts the peak spectral heat flux toward higher frequencies attests to the tunable bandgap of graphene. Although graphene covering of VACNT does not offer many magnitudes of near-field heat flux enhancement over uncovered VACNT, this study identifies conditions (i.e. gap distance and doping) that best augments heat transfer to that of VACNT arrays. In addition, this study demonstrates the near-field Poynting vector to determine the energy absorption due to graphene. It is found that graphene, in low frequencies and high chemical potentials, attenuates large penetration depths of hyperbolic modes, thereby increasing the contribution of graphene-graphene surface plasmons. This study has an impact toward designing carbon-based emitters and thermal junctions.

  14. Method of processing materials using an inductively coupled plasma

    DOEpatents

    Hull, Donald E.; Bieniewski, Thomas M.

    1989-01-01

    A method for coating surfaces or implanting ions in an object using an inductively coupled plasma. The method provides a gas-free environment, since the plasma is formed without using a gas. The coating material or implantation material is intitially in solid form.

  15. High ethylene to ethane processes for oxidative coupling

    DOEpatents

    Chafin, Richard B.; Warren, Barbara K.

    1991-01-01

    Oxidative coupling of lower alkane to higher hydrocarbon is conducted using catalyst comprising barium and/or strontium component and a metal oxide combustion promoter in the presence of vapor phase halogen component. High ethylene to ethane mole ratios in the product can be obtained over extended operating periods.

  16. High ethylene to ethane processes for oxidative coupling

    DOEpatents

    Chafin, R.B.; Warren, B.K.

    1991-12-17

    Oxidative coupling of lower alkane to higher hydrocarbon is conducted using a catalyst comprising barium and/or strontium component and a metal oxide combustion promoter in the presence of vapor phase halogen component. High ethylene to ethane mole ratios in the product can be obtained over extended operating periods.

  17. Imaging finite-fault earthquake source by iterative deconvolution and stacking (IDS) of near-field complete seismograms

    NASA Astrophysics Data System (ADS)

    Wang, Rongjiang; Zhang, Yong; Zschau, Jochen; Chen, Yun-tai; Parolai, Stefano; Diao, Faqi; Dahm, Torsten

    2015-04-01

    By combining the complementary advantages of conventional inversion and back-projection methods, we have developed an iterative deconvolution and stacking (IDS) approach for imaging earthquake rupture processes with near-field complete waveform data. This new approach does not need any manual adjustment of the physical (empirical) constraints, such as restricting the rupture time and duration, smoothing the spatiotemporal slip distribution, etc., and therefore has the ability to image complex multiple ruptures automatically. The advantages of the IDS method over traditional linear or non-linear optimization algorithms are demonstrated by the case studies of the 2008 Wenchuan (China), 2011 Tohoku (Japan) and 2014 Pisagua-Iquique (Chile) earthquakes. For such large earthquakes, the IDS method is considerably more stable and efficient than previous inversion methods. Additionally, the robustness of this method is demonstrated by comprehensive synthetic tests, indicating its potential contribution to tsunami early warning and earthquake rapid response systems. It is also shown that the IDS method can be used for teleseismic waveform inversions. For the 2011 Tohoku earthquakes, for example, the IDS method can provide, without tuning any physical or empirical constraints, teleseismic rupture models consistent with those derived from the near-field GPS and strong-motion data.

  18. E-field extraction from Hx- and Hy- near field values by using plane wave spectrum method

    NASA Astrophysics Data System (ADS)

    Ravelo, B.; Riah, Z.; Baudry, D.; Mazari, B.

    2011-01-01

    This paper deals with a technique for calculating the 3D E-field components knowing only the two components (Hx and Hy) of the H-field in near-zone. The originality of the under study technique lies on the possibility to take into account the evanescent wave influences. The presented E-field extraction process is based on the exploitation of the Maxwell-Ampere relation combined with the plane wave spectrum (PWS) method. The efficiency of the proposed technique is evidenced by comparing the E-field deduced from H-field and the own E-field radiated by the association of electrical- and also magnetic- elementary dipoles in different configurations by using Matlab text programming environment. In addition, as a concrete demonstrator, the concept was also validated with the computation of EM-wave radiated by an open-end microstrip transmission line. As result of comparison, very good agreement between the exact E-field and that one extracted from the H-field was realized by considering the near-field scanned at the height, z = 5 mm and 8 mm above the under test structure at the operating frequency, f = 1 GHz. The presented technique can simplify the difficulties about the E-near-field measurement in EMC applications.

  19. Analysis of near-field method for optical data storage using microstrip probe under illumination and illumination-collection mode

    NASA Astrophysics Data System (ADS)

    Morozov, Yevhenii; Kryuchyn, Andriy A.; Petrov, Viacheslav V.; Lapchuk, Anatoliy S.

    2014-09-01

    Results of numerical simulation of near-field optical data storage using microstrip probe are presented. Simulation is carried out on the basis of the finite-difference time-domain method. Features of the information reading process from the ROM and RW (based on the phase transmissions of Ge2Sb2Te5 film) formats of optical discs under illumination and illumination-collection mode are analyzed and considered. Mathematical modeling has shown that the signal from the ROM-format disc under illumination mode, despite the fact that the probe has a significant far-field transmission coefficient, has a large crosstalk and small spatial resolution (significantly worse than a size of probe aperture). Unlike illumination mode, signal under illumination-collection mode (pure near-field method) has a resolution close to the size of the aperture, good amplitude and contrast, as well as relatively low crosstalk. However, information reading under illumination-collection mode from RW-format disc is not able to get the same good quality signal. Therefore the further optimization of the method is required to improve the signal quality of RW format.

  20. Coupling processes related to the Sun-weather problem

    NASA Technical Reports Server (NTRS)

    Goldberg, R. A.; Herman, J. R.

    1979-01-01

    Physical mechanisms for coupling the energetics of solar activity to meteorological responses are reviewed. Although several hypotheses have been advanced, none can be said to be sufficiently complete to be applied to weather or climate prediction. Solar activity indicators potentially useful for forecasting are identified, including sunspots, solar flares, and magnetic sector boundary crossings. Additional experiments, studies, and analyses are required before Sun-weather concepts can be utilized for predicting meteorological responses.

  1. Photodissociation path in H2 + induced by nonuniform optical near fields: Two-step excitation via vibrationally excited states

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Maiku; Nobusada, Katsuyuki

    2016-02-01

    In this paper, effects of the spatial nonuniformity of an optical near field (ONF) on the molecular photodissociation process are presented. The dissociation dynamics of H2 + was theoretically investigated by solving a non-Born-Oppenheimer Schrödinger equation. It was found that in addition to two dissociation mechanisms, which are one-photon and three-photon processes induced by uniform laser light excitation, the nonuniform ONF opens another dissociation path: two-step excitation mediated by vibrationally excited states. The nonuniformity of the ONF causes a transition between vibrational states that is forbidden according to conventional selection rules, leading to the dissociation path. The dependences of photodissociation on the intensity and nonuniformity of the ONF were calculated and the results validated the two-step dissociation mechanism.

  2. Thin film coating process using an inductively coupled plasma

    DOEpatents

    Kniseley, Richard N.; Schmidt, Frederick A.; Merkle, Brian D.

    1990-01-30

    Thin coatings of normally solid materials are applied to target substrates using an inductively coupled plasma. Particles of the coating material are vaporized by plasma heating, and pass through an orifice to a first vacuum zone in which the particles are accelerated to a velocity greater than Mach 1. The shock wave generated in the first vacuum zone is intercepted by the tip of a skimmer cone that provides a second orifice. The particles pass through the second orifice into a second zone maintained at a higher vacuum and impinge on the target to form the coating. Ultrapure coatings can be formed.

  3. Sparse Multi-Static Arrays for Near-Field Millimeter-Wave Imaging

    SciTech Connect

    Sheen, David M.

    2013-12-31

    This paper describes a novel design technique for sparse multi-static linear arrays. The methods described allow the development of densely sampled linear arrays suitable for high-resolution near-field imaging that require dramatically fewer antenna and switch elements than the previous state of the art. The techniques used are related to sparse array techniques used in radio astronomy applications, but differ significantly in design due to the transmit-receive nature of the arrays, and the application to linear arrays that achieve dense uniform sampling suitable for high-resolution near-field imaging. As many as 3 to 5 or more samples per antenna can be obtained, compared to 1 sample per antenna for the current state of the art. This could dramatically reduce cost and improve performance over current active millimeter-wave imaging systems.

  4. Light concentration in the near-field of dielectric spheroidal particles with mesoscopic sizes.

    PubMed

    Mendes, Manuel J; Tobías, Ignacio; Martí, Antonio; Luque, Antonio

    2011-08-15

    This paper presents a numerical study of the light focusing properties of dielectric spheroids with sizes comparable to the illuminating wavelength. An analytical separation-of-variables method is used to determine the electric field distribution inside and in the near-field outside the particles. An optimization algorithm was implemented in the method to determine the particles' physical parameters that maximize the forward scattered light in the near-field region. It is found that such scatterers can exhibit pronounced electric intensity enhancement (above 100 times the incident intensity) in their close vicinity, or along wide focal regions extending to 10 times the wavelength. The results reveal the potential of wavelength-sized spheroids to manipulate light beyond the limitations of macroscopic geometrical optics. This can be of interest for several applications, such as light management in photovoltaics. PMID:21934983

  5. CFD predictions of near-field pressure signatures of a low-boom aircraft

    NASA Technical Reports Server (NTRS)

    Fouladi, Kamran; Baize, Daniel G.

    1992-01-01

    A three dimensional Euler marching code has been utilized to predict near-field pressure signatures of an aircraft with low boom characteristics. Computations were extended to approximately six body lengths aft of the aircraft in order to obtain pressure data at three body lengths below the aircraft for a cruise Mach number of 1.6. The near-field pressure data were extrapolated to the ground using a Whitham based method. The distance below the aircraft where the pressure data are attained is defined in this paper as the 'separation distance.' The influences of separation distances and the still highly three-dimensional flow field on the predicted ground pressure signatures and boom loudness are presented in this paper.

  6. Dynamic near-field nanofocusing by V-shaped metal groove via a femtosecond laser excitation

    NASA Astrophysics Data System (ADS)

    Du, Guangqing; Yang, Qing; Chen, Feng; Lu, Yu; Ou, Yan; Yong, Jiale; Hou, Xun

    2016-03-01

    The ultrafast dynamics of plasmonic near-field nanofocusing by a V-shaped groove milled on Au film via a femtosecond laser excitation is theoretically studied based on finite element method. The spatiotemporal evolution of the focused e-fields around the V-groove geometry is obtained. It is revealed that the strong nanofocusing at the V-shaped groove occurs at the moderate electron temperature of 3000 K in the electron-phonon uncoupled state via a femtosecond laser pulse excitation. The phenomenon is explained as the electron thermal dynamics manipulation of plasmon resonances due to femtosecond laser fluence modifications. This study provides basic understanding of ultrafast dynamics of near-field nanofocusing in V-shaped geometry for wide applications in the fields such as super-resolution imaging, SERS, and photothermal therapy.

  7. Near-field testing of the 5-meter model of the tetrahedral truss antenna

    NASA Technical Reports Server (NTRS)

    Kefauver, Neill; Cencich, Tom; Osborn, Jim; Osmanski, J. T.

    1986-01-01

    This report documents the technical results from near-field testing of the General Dynamics 5-meter model of the tetrahedral truss antenna at the Martin Marietta Denver Aerospace facility. A 5-meter square side of the tetrahedral served as the perimeter of the antenna, and a mesh surface and extensive surface contouring cord network was used to create a parabolic aperture shape to within an rms accuracy of 30 mils or better. Pattern measurements were made with offset feed systems radiating at frequencies of 7.73, 11.60, 2.27, and 4.26 (all in GHz). This report discusses the method of collecting the data, system measurement accuracy, the test data compiled, and diagostics and isolation of causes of pattern results. The technique of using near-field phase for measuring surface mechanical tolerances is included. Detailed far field antenna patterns and their implications are provided for all tests conducted.

  8. Reactive Near-field to Far-field Transformation at 30 to 150MHz

    NASA Astrophysics Data System (ADS)

    Watanabe, Takuto; Hashimoto, Osamu; Takizawa, Koji; Kurihara, Hiroshi

    In this paper, radiation patterns of a small loop antenna (l<λ/10) were estimated by reactive near-field (E- and H- field) obtained by FIT (Finite Integral Technique) analysis at 30 to 150MHz applying the equivalent theorem. Then, accuracy of estimation was examined by variations of sampling intervals of reactive near-field on a virtual closed surface S (L×L×L) divided into Δx=Δy=Δz. As a result, an estimated result at the condition of Δx=Δy=Δz=L/30 was good agreement with the simulation (MW-studio/CST) within 0.3dB difference. Moreover differences of estimated results, between the minimum interval (L/30) and the maximum interval (L), were within 3.05dB at 30MHz, 3.44dB at 75MHz, and 3.56dB at 150MHz.

  9. Information Content of the Near-Field I: Two-Dimensional Samples

    NASA Technical Reports Server (NTRS)

    Frazin, Richard A.; Fischer, David G.; Carney, P. Scott

    2004-01-01

    Limits on the effective resolution of many optical near-field experiments are investigated. The results are applicable to variants of total-internal-reflection microscopy (TIRM), photon-scanning-tunneling microscopy (PSTM), and near-field-scanning-optical microscopy (NSOM) in which the sample is weakly scattering and the direction of illumination may be controlled. Analytical expressions for the variance of the estimate of the complex susceptibility of an unknown two-dimensional object as a function of spatial frequency are obtained for Gaussian and Poisson noise models, and a model-independent measure is examined. The results are used to explore the transition from near-zone to far-zone detection. It is demonstrated that the information content of the measurements made at a distance of even one wavelength away from the sample is already not much different from the information content of the far field. Copyright 2004 Optical Society of America

  10. Hyperbolic phonon-polaritons in boron nitride for near-field optical imaging and focusing

    NASA Astrophysics Data System (ADS)

    Li, Peining; Lewin, Martin; Kretinin, Andrey V.; Caldwell, Joshua D.; Novoselov, Kostya S.; Taniguchi, Takashi; Watanabe, Kenji; Gaussmann, Fabian; Taubner, Thomas

    2015-06-01

    Hyperbolic materials exhibit sub-diffractional, highly directional, volume-confined polariton modes. Here we report that hyperbolic phonon polaritons allow for a flat slab of hexagonal boron nitride to enable exciting near-field optical applications, including unusual imaging phenomenon (such as an enlarged reconstruction of investigated objects) and sub-diffractional focusing. Both the enlarged imaging and the super-resolution focusing are explained based on the volume-confined, wavelength dependent propagation angle of hyperbolic phonon polaritons. With advanced infrared nanoimaging techniques and state-of-art mid-infrared laser sources, we have succeeded in demonstrating and visualizing these unexpected phenomena in both Type I and Type II hyperbolic conditions, with both occurring naturally within hexagonal boron nitride. These efforts have provided a full and intuitive physical picture for the understanding of the role of hyperbolic phonon polaritons in near-field optical imaging, guiding, and focusing applications.

  11. Hyperbolic phonon-polaritons in boron nitride for near-field optical imaging and focusing.

    PubMed

    Li, Peining; Lewin, Martin; Kretinin, Andrey V; Caldwell, Joshua D; Novoselov, Kostya S; Taniguchi, Takashi; Watanabe, Kenji; Gaussmann, Fabian; Taubner, Thomas

    2015-01-01

    Hyperbolic materials exhibit sub-diffractional, highly directional, volume-confined polariton modes. Here we report that hyperbolic phonon polaritons allow for a flat slab of hexagonal boron nitride to enable exciting near-field optical applications, including unusual imaging phenomenon (such as an enlarged reconstruction of investigated objects) and sub-diffractional focusing. Both the enlarged imaging and the super-resolution focusing are explained based on the volume-confined, wavelength dependent propagation angle of hyperbolic phonon polaritons. With advanced infrared nanoimaging techniques and state-of-art mid-infrared laser sources, we have succeeded in demonstrating and visualizing these unexpected phenomena in both Type I and Type II hyperbolic conditions, with both occurring naturally within hexagonal boron nitride. These efforts have provided a full and intuitive physical picture for the understanding of the role of hyperbolic phonon polaritons in near-field optical imaging, guiding, and focusing applications. PMID:26112474

  12. Writing 40 nm marks by using a beaked metallic plate near-field optical probe.

    PubMed

    Matsumoto, T; Anzai, Y; Shintani, T; Nakamura, K; Nishida, T

    2006-01-15

    We have developed a near-field optical probe that uses a triangular metallic plate with a three-dimensionally tapered apex as a light source for thermally assisted magnetic recording. Numerical analysis using a finite-element method shows that the size of the optical spot generated at the apex is 15 nm x 20 nm, and the efficiency (defined as the ratio between the power of the optical near field at the surface of the recording medium and that of the incident light) is 15% when the incident light is focused by a lens with a numerical aperture of 0.8. The metallic plate was fabricated on the surface of a quartz slider and used for writing marks on a phase change recording medium. The marks were observed with a scanning electron microscope, and we confirmed that marks with a diameter of 40 nm were successfully written on the medium. PMID:16441049

  13. Analysis of optical near-field energy transfer by stochastic model unifying architectural dependencies

    SciTech Connect

    Naruse, Makoto; Akahane, Kouichi; Yamamoto, Naokatsu; Holmström, Petter; Thylén, Lars; Huant, Serge; Ohtsu, Motoichi

    2014-04-21

    We theoretically and experimentally demonstrate energy transfer mediated by optical near-field interactions in a multi-layer InAs quantum dot (QD) structure composed of a single layer of larger dots and N layers of smaller ones. We construct a stochastic model in which optical near-field interactions that follow a Yukawa potential, QD size fluctuations, and temperature-dependent energy level broadening are unified, enabling us to examine device-architecture-dependent energy transfer efficiencies. The model results are consistent with the experiments. This study provides an insight into optical energy transfer involving inherent disorders in materials and paves the way to systematic design principles of nanophotonic devices that will allow optimized performance and the realization of designated functions.

  14. Near-field testing of the 30 GHz TRW proof-of-concept multibeam antenna

    NASA Technical Reports Server (NTRS)

    Kunath, R. R., Jr.; Zakrajsek, R. J.

    1986-01-01

    Near-field testing was conducted on the 30 GHz TRW proof-of-concept (POC) Multibeam Antenna (MBA). The TRW POC MBA is a dual offset Cassegrain reflector system using a 2.7 m main reflector. This configuration was selected to assess the ability to create both multiple fixed and scanned spot beams. The POC configuration investigated frequency reuse via spatial separation of beams, polarization selectivity and time division multiple access scanning at 30 GHz. Measurements of directivity, sidelobe level, and pattern were made at NASA Lewis Research Center's Near-Field Antenna Test Facility. Presented in this paper are complete results of these measurements. Included is a detailed discussion of all testing procedures and parameters. Results of additional testing used to evaluate diffraction effects of the subreflector and distortions of the main reflector are also presented.

  15. Near-field focusing properties of zone plates in visible regime--new insights.

    PubMed

    Mote, Rakesh G; Yu, S F; Ng, B K; Zhou, Wei; Lau, S P

    2008-06-23

    Near-field focusing properties of zone plates are investigated in the visible regime by a 3-dimensional finite-difference time-domain method. It is shown that Frensel zone plates (FZPs) with metallic coatings can achieve subwavelength focusing in the visible wavelength. The characteristics of subwavelength focusing are found to be independent of the type of metal coatings used. All the FZPs exhibit similar shift in focal length and depth of focus when compared with classical calculations. These results indicate that plasmonic waves do not contribute to subwavelength focusing. Instead the subwavelength focusing characteristic is attributed to the interference of diffracted evanescent waves from a large numerical aperture. It is found that the near-field focusing of FZPs suppresses higher order foci such that the corresponding diffraction efficiency is improved. The use of phase zone plate structured on glass without opaque coating is proposed to improve the diffraction efficiency of subwavelength focusing. PMID:18575522

  16. Oscillatory penetration of near-fields in plasmonic excitation at metal-dielectric interfaces

    NASA Astrophysics Data System (ADS)

    Lee, S. C.; Kang, J. H.; Park, Q.-H.; Krishna, S.; Brueck, S. R. J.

    2016-04-01

    The electric field immediately below an illuminated metal-film that is perforated with a hole array on a dielectric consists of direct transmission and scattering of the incident light through the holes and evanescent near-field from plasmonic excitations. Depending on the size and shape of the hole apertures, it exhibits an oscillatory decay in the propagation direction. This unusual field penetration is explained by the interference between these contributions, and is experimentally confirmed through an aperture which is engineered with four arms stretched out from a simple circle to manipulate a specific plasmonic excitation available in the metal film. A numerical simulation quantitatively supports the experiment. This fundamental characteristic will impact plasmonics with the near-fields designed by aperture engineering for practical applications.

  17. Near-field radiative heat transfer between metamaterials coated with silicon carbide thin films

    SciTech Connect

    Basu, Soumyadipta Yang, Yue; Wang, Liping

    2015-01-19

    In this letter, we study the near-field radiative heat transfer between two metamaterial substrates coated with silicon carbide (SiC) thin films. It is known that metamaterials can enhance the near-field heat transfer over ordinary materials due to excitation of magnetic plasmons associated with s polarization, while strong surface phonon polariton exists for SiC. By careful tuning of the optical properties of metamaterial, it is possible to excite electrical and magnetic resonances for the metamaterial and surface phonon polaritons for SiC at different spectral regions, resulting in the enhanced heat transfer. The effect of the SiC film thickness at different vacuum gaps is investigated. Results obtained from this study will be beneficial for application of thin film coatings for energy harvesting.

  18. An Analysis of Near Fields of 34m Antennas of JPL/NASA Deep Space Network

    NASA Technical Reports Server (NTRS)

    Jamnejad, Vahraz; Juan, Nuria Llombart

    2011-01-01

    This paper addresses the issue of calculating near fields of the 34m Beam Waveguide (BWG) antennas of the NASA/JPL Deep Space Network (DSN). Calculating the near fields of DSN antennas are of interest in receive mode where the transmitting signals from nearby flying objects such as helicopters and airplanes could interfere with the operation of sensitive RF receiving system of DSN antennas, and in the transmit mode where fields from high-powered DSN antennas interfere with receivers on nearby flying objects, as well as safety considerations for the operators and visitors to the grounds surrounding the antenna sites. A complete and detailed analysis has been performed using PO/PTD techniques, including surface errors and support struts effects. Some results are presented, including comparisons with preliminary field tests.

  19. Hyperbolic phonon-polaritons in boron nitride for near-field optical imaging and focusing

    PubMed Central

    Li, Peining; Lewin, Martin; Kretinin, Andrey V.; Caldwell, Joshua D.; Novoselov, Kostya S.; Taniguchi, Takashi; Watanabe, Kenji; Gaussmann, Fabian; Taubner, Thomas

    2015-01-01

    Hyperbolic materials exhibit sub-diffractional, highly directional, volume-confined polariton modes. Here we report that hyperbolic phonon polaritons allow for a flat slab of hexagonal boron nitride to enable exciting near-field optical applications, including unusual imaging phenomenon (such as an enlarged reconstruction of investigated objects) and sub-diffractional focusing. Both the enlarged imaging and the super-resolution focusing are explained based on the volume-confined, wavelength dependent propagation angle of hyperbolic phonon polaritons. With advanced infrared nanoimaging techniques and state-of-art mid-infrared laser sources, we have succeeded in demonstrating and visualizing these unexpected phenomena in both Type I and Type II hyperbolic conditions, with both occurring naturally within hexagonal boron nitride. These efforts have provided a full and intuitive physical picture for the understanding of the role of hyperbolic phonon polaritons in near-field optical imaging, guiding, and focusing applications. PMID:26112474

  20. The results of near-field thermal and mechanical calculations of thermal loading schemes

    SciTech Connect

    Holland, J.F.

    1992-12-31

    Two waste emplacement schemes,borehole and in-drift are under evaluation as potential repository drift geometries for the Yucca Mountain Site Characterization Project Calculations were performed to examinethe systems implications of various thermal loadings on the near- and far-field repository environments. Ms paper reports the results of two-dimensional finite element analyses of the near-field thermal and structural response of the potential repository. Thermal calculations were run to 1000 years and mechanical calculations were run to 75 years. the time when the drifts will be backfilled. Local areal power densities (LAPDs) of 57, 80, and 100 kW/acre were used in the calculations. Both emplacement schemes meet current near-field thermal performance goals for all loadings examined. The mechanical calculations predict no intact rock failure, limited joint slippage around the drifts, and closure of apertures for vertical fractures above and below the drifts.