LABORATORY ANALYSES OF CORONA DISCHARGES

EPA Science Inventory

The paper discusses an experimental research program to characterize corona generation from different electrode geometries in a range of conditions comparable to those found in electrostatic precipitators (ESPs). A wire-parallel plate device and a wire-cylinder device were used t...

Electrostatic Structure and Double-Probe Performance in Tenuous Plasmas

NASA Astrophysics Data System (ADS)

Cully, C. M.; Ergun, R. E.

2006-12-01

Many in-situ plasma instruments are affected by the local electrostatic structure surrounding the spacecraft. In order to better understand this structure, we have developed a fully 3-dimensional self-consistent model that uses realistic spacecraft geometry, including thin (<1 mm) wires and long (>100m) booms, with open boundary conditions. One of the more surprising results is that in tenuous plasmas, the charge on the booms can dominate over the charge on the spacecraft body. For instruments such as electric field double probes and boom-mounted low-energy particle detectors, this challenges the existing paradigm: long booms do not allow the probes to escape the spacecraft potential. Instead, the potential structure simply expands as the boom is deployed. We then apply our model to the double-probe Electric Field and Waves (EFW) instruments on Cluster, and predict the magnitudes of the main error sources. The overall error budget is consistent with experiment, and the model yields some additional interesting insights. We show that the charge in the photoelectron cloud is relatively unimportant, and that the spacecraft potential is typically underestimated by about 20% by double-probe experiments.

Radiation and scattering by thin-wire structures in the complex frequency domain. [electromagnetic theory for thin-wire antennas

NASA Technical Reports Server (NTRS)

Richmond, J. H.

1974-01-01

Piecewise-sinusoidal expansion functions and Galerkin's method are employed to formulate a solution for an arbitrary thin-wire configuration in a homogeneous conducting medium. The analysis is performed in the real or complex frequency domain. In antenna problems, the solution determines the current distribution, impedance, radiation efficiency, gain and far-field patterns. In scattering problems, the solution determines the absorption cross section, scattering cross section and the polarization scattering matrix. The electromagnetic theory is presented for thin wires and the forward-scattering theorem is developed for an arbitrary target in a homogeneous conducting medium.

PILOT-SCALE EVALUATION OF TOP-INLET AND ADVANCED ELECTROSTATIC FILTRATION

EPA Science Inventory

The report gives results of an evaluation of Advanced Electrostatic Augmentation of Fabric Filtration (ESFF) on a slipstream from a stoker-fired boiler. Advanced ESFF, with its characteristic high-voltage center-wire electrode, was compared with conventional filter bags in the sa...

Electrostatic and electrodynamic response properties of nanostructures

NASA Astrophysics Data System (ADS)

Ayaz, Yuksel

1999-11-01

This thesis addresses the problem of nanostructure dielectric response to excitation by electric fields, both in the electrostatic c→infinity and the electrodynamic regimes. The nanostructures treated include planar quantum wells and quantum wires embedded in the vicinity of the bounding surface of the host semiconductor medium. Various cases are analyzed, including a single well or wire, a double well or wire, a lattice of N wells or wires and an infinite superlattice of wells or wires. The host medium is considered to have phonons and/or a bulk semiconductor plasma which interact with the plasmons of the embedded quantum wells or wires, and the host plasma is treated in both the local "cold" plasma regime and the nonlocal "hot" plasma regime. New hybridized quantum plasma collective modes emerge from these studies. The techniques employed here include the variational differential formulation of integral equations for the inverse dielectric function (in electrostatic case) and the dyadic Green's function (in the electrodynamic case) for the various systems described above. These integral equations are then solved in frequency-position representation by a variety of techniques depending on the geometrical features of the particular problem. Explicit closed form solutions for the inverse dielectric function or dyadic Green's function facilitate identification of the coupled collective modes in terms of their frequency poles, and the residues at the pole positions provide the relative amplitudes with which these normal modes respond to external excitation. Interesting features found include, for example, explicit formulas showing the transference of coupling of a two dimensional (2D) quantum well plasmon from a surface phonon to a bulk phonon as the 2D quantum well is displaced away from the bounding surface, deeper into the medium.

Charged particle tracking through electrostatic wire meshes using the finite element method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Devlin, L. J.; Karamyshev, O.; Welsch, C. P., E-mail: carsten.welsch@cockcroft.ac.uk

Wire meshes are used across many disciplines to accelerate and focus charged particles, however, analytical solutions are non-exact and few codes exist which simulate the exact fields around a mesh with physical sizes. A tracking code based in Matlab-Simulink using field maps generated using finite element software has been developed which tracks electrons or ions through electrostatic wire meshes. The fields around such a geometry are presented as an analytical expression using several basic assumptions, however, it is apparent that computational calculations are required to obtain realistic values of electric potential and fields, particularly when multiple wire meshes are deployed.more » The tracking code is flexible in that any quantitatively describable particle distribution can be used for both electrons and ions as well as other benefits such as ease of export to other programs for analysis. The code is made freely available and physical examples are highlighted where this code could be beneficial for different applications.« less

Durability Evaluation of a Thin Film Sensor System With Enhanced Lead Wire Attachments on SiC/SiC Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Lei, Jih-Fen; Kiser, J. Douglas; Singh, Mrityunjay; Cuy, Mike; Blaha, Charles A.; Androjna, Drago

2000-01-01

An advanced thin film sensor system instrumented on silicon carbide (SiC) fiber reinforced SiC matrix ceramic matrix composites (SiC/SiC CMCs), was evaluated in a Mach 0.3 burner rig in order to determine its durability to monitor material/component surface temperature in harsh environments. The sensor system included thermocouples in a thin film form (5 microns thick), fine lead wires (75 microns diameter), and the bonds between these wires and the thin films. Other critical components of the overall system were the heavy, swaged lead wire cable (500 microns diameter) that contained the fine lead wires and was connected to the temperature readout, and ceramic attachments which were bonded onto the CMCs for the purpose of securing the lead wire cables, The newly developed ceramic attachment features a combination of hoops made of monolithic SiC or SiC/SiC CMC (which are joined to the test article) and high temperature ceramic cement. Two instrumented CMC panels were tested in a burner rig for a total of 40 cycles to 1150 C (2100 F). A cycle consisted of rapid heating to 1150 C (2100 F), a 5 minute hold at 1150 C (2100 F), and then cooling down to room temperature in 2 minutes. The thin film sensor systems provided repeatable temperature measurements for a maximum of 25 thermal cycles. Two of the monolithic SiC hoops debonded during the sensor fabrication process and two of the SiC/SiC CMC hoops failed during testing. The hoops filled with ceramic cement, however, showed no sign of detachment after 40 thermal cycle test. The primary failure mechanism of this sensor system was the loss of the fine lead wire-to-thin film connection, which either due to detachment of the fine lead wires from the thin film thermocouples or breakage of the fine wire.

Attachment of lead wires to thin film thermocouples mounted on high temperature materials using the parallel gap welding process

NASA Technical Reports Server (NTRS)

Holanda, Raymond; Kim, Walter S.; Pencil, Eric; Groth, Mary; Danzey, Gerald A.

1990-01-01

Parallel gap resistance welding was used to attach lead wires to sputtered thin film sensors. Ranges of optimum welding parameters to produce an acceptable weld were determined. The thin film sensors were Pt13Rh/Pt thermocouples; they were mounted on substrates of MCrAlY-coated superalloys, aluminum oxide, silicon carbide and silicon nitride. The entire sensor system is designed to be used on aircraft engine parts. These sensor systems, including the thin-film-to-lead-wire connectors, were tested to 1000 C.

Evaluating the Gradient of the Thin Wire Kernel

NASA Technical Reports Server (NTRS)

Wilton, Donald R.; Champagne, Nathan J.

2008-01-01

Recently, a formulation for evaluating the thin wire kernel was developed that employed a change of variable to smooth the kernel integrand, canceling the singularity in the integrand. Hence, the typical expansion of the wire kernel in a series for use in the potential integrals is avoided. The new expression for the kernel is exact and may be used directly to determine the gradient of the wire kernel, which consists of components that are parallel and radial to the wire axis.

Martian Atmospheric Pressure Static Charge Elimination Tool

NASA Technical Reports Server (NTRS)

Johansen, Michael R.

2014-01-01

A Martian pressure static charge elimination tool is currently in development in the Electrostatics and Surface Physics Laboratory (ESPL) at NASA's Kennedy Space Center. In standard Earth atmosphere conditions, static charge can be neutralized from an insulating surface using air ionizers. These air ionizers generate ions through corona breakdown. The Martian atmosphere is 7 Torr of mostly carbon dioxide, which makes it inherently difficult to use similar methods as those used for standard atmosphere static elimination tools. An initial prototype has been developed to show feasibility of static charge elimination at low pressure, using corona discharge. A needle point and thin wire loop are used as the corona generating electrodes. A photo of the test apparatus is shown below. Positive and negative high voltage pulses are sent to the needle point. This creates positive and negative ions that can be used for static charge neutralization. In a preliminary test, a floating metal plate was charged to approximately 600 volts under Martian atmospheric conditions. The static elimination tool was enabled and the voltage on the metal plate dropped rapidly to -100 volts. This test data is displayed below. Optimization is necessary to improve the electrostatic balance of the static elimination tool.

Electrostatic bonding of thin (cycle sine 3 mil) 7070 cover glass to Ta2O5 AR-coated thin (cycle sine 2 mil) silicon wafers and solar cells

NASA Technical Reports Server (NTRS)

Egelkrout, D. W.

1981-01-01

Electrostatic bonding of thin cover glass to thin solar cells was researched. Silicon solar cells, wafers, and Corning 7070 glass of from about 0.002" to about 0.003" in thickness were used in the investigation to establish optimum parameters for producing mechanically acceptable bonds while minimizing thermal stresses and resultant solar cell electrical parameter degradation.

Lorentz Contraction and Current-Carrying Wires

ERIC Educational Resources Information Center

van Kampen, Paul

2008-01-01

The force between two parallel current-carrying wires is investigated in the rest frames of the ions and the electrons. A straightforward Lorentz transformation shows that what appears as a purely magnetostatic force in the ion frame appears as a combined magnetostatic and electrostatic force in the electron frame. The derivation makes use of a…

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Joshua, E-mail: joshuk7@uci.edu; Park, Sun-Jun; Nguyen, Thao

With the growing prominence of wearable electronic technology, there is a need to improve the mechanical reliability of electronics for more demanding applications. Conductive wires represent a vital component present in all electronics. Unlike traditional planar and rigid electronics, these new wearable electrical components must conform to curvilinear surfaces, stretch with the body, and remain unobtrusive and low profile. In this paper, the piezoresistive response of shrink induced wrinkled gold thin films under strain demonstrates robust conductive performance in excess of 200% strain. Importantly, the wrinkled metallic thin films displayed negligible change in resistance of up to 100% strain. Themore » wrinkled metallic wires exhibited consistent performance after repetitive strain. Importantly, these wrinkled thin films are inexpensive to fabricate and are compatible with roll to roll manufacturing processes. We propose that these wrinkled metal thin film wires are an attractive alternative to conventional wires for wearable applications.« less

Thin wire pointing method

NASA Technical Reports Server (NTRS)

Green, G.; Mattauch, R. J. (Inventor)

1983-01-01

A method is described for forming sharp tips on thin wires, in particular phosphor bronze wires of diameters such as one-thousandth inch used to contact micron size Schottky barrier diodes, which enables close control of tip shape and which avoids the use of highly toxic solutions. The method includes dipping an end of a phosphor bronze wire into a dilute solution of sulfamic acid and applying a current through the wire to electrochemically etch it. The humidity in the room is controlled to a level of less than 50%, and the voltage applied between the wire and another electrode in the solutions is a half wave rectified voltage. The current through the wire is monitored, and the process is stopped when the current falls to a predetermined low level.

Attachment of Free Filament Thermocouples for Temperature Measurements on CMC

NASA Technical Reports Server (NTRS)

Lei, Jih-Fen; Cuy, Michael D.; Wnuk, Stephen P.

1997-01-01

Ceramic Matrix Composites (CMC) are being developed for use as enabling materials for advanced aeropropulsion engine and high speed civil transport applications. The characterization and testing of these advanced materials in hostile, high-temperature environments require accurate measurement of the material temperatures. Commonly used wire Thermo-Couples (TC) can not be attached to this ceramic based material via conventional spot-welding techniques. Attachment of wire TC's with commercially available ceramic cements fail to provide sufficient adhesion at high temperatures. While advanced thin film TC technology provides minimally intrusive surface temperature measurement and has good adhesion on the CMC, its fabrication requires sophisticated and expensive facilities and is very time consuming. In addition, the durability of lead wire attachments to both thin film TC's and the substrate materials requires further improvement. This paper presents a newly developed attachment technique for installation of free filament wire TC's with a unique convoluted design on ceramic based materials such as CMC's. Three CMC's (SiC/SiC CMC and alumina/alumina CMC) instrumented with type IC, R or S wire TC's were tested in a Mach 0.3 burner rig. The CMC temperatures measured from these wire TC's were compared to that from the facility pyrometer and thin film TC's. There was no sign of TC delamination even after several hours exposure to 1200 C. The test results proved that this new technique can successfully attach wire TC's on CMC's and provide temperature data in hostile environments. The sensor fabrication process is less expensive and requires very little time compared to that of the thin film TC's. The same installation technique/process can also be applied to attach lead wires for thin film sensor systems.

Investigation of Electrostatic Charge in Hose Lines

DTIC Science & Technology

2006-10-01

of the system. A INSULATORINSULATOR Ir1 Q Q dH vH A INSULATORINSULATOR Ir2 Q dm dl 2 vm LmLH S1 S2 S3EXTERNAL WIRE BRAID ON HOSE vl 2vm dm Lm dl...sizes of fuel hoses , including hoses with and without integrally bonded grounding wire braid ; (4) Different lengths of hose test sections; (5...Different earth grounding contact conditions along the hose test section, such as: (i) Complete insulation from the ground; (ii) Wire braid conductor along

CubeSat Measurement and Demonstration of Coulomb Drag Effect for Deorbiting

NASA Astrophysics Data System (ADS)

2013-08-01

Deorbiting satellites by passive or active electrodynamic tether Lorentz force effect is well known. Probably less well known is that a charged conducting tether also interacts with the streaming ionospheric plasma by electrostatic Coulomb drag. Especially for the case of small satellites deorbited by thin tethers, the Coulomb drag effect can be larger than the Lorentz force effect. When a tether is optimised for Coulomb drag, the goal is only to keep it charged. The fact that the charged tether gathers current is then a side effect which can be minimised by using negative voltage and by making the tether very thin. Using negative voltage in most cases implies that one can use the satellite's conducting surface as the other electrode so that no electron or ion emitter is needed on the spacecraft for closing the circuit. Thinness of the tether is a large benefit not only from the mass saving and power consumption minimisation points of view, but also because a sufficiently thin tether (made e.g. four 25-50 micrometre thin aluminium wires) poses nearly no threat to other space assets in the even of an unwanted collision. ESTCube-1 is an Estonian 1U CubeSat which is scheduled for Vega launch in May 2013 to 680 km polar orbit. The payload of ESTCube-1 is a 10 m long Heytether made of 25-50 aluminium wires which can be charged to plus orminus 500 V by onboard voltage sources and electron gun. The mission of ESTCube-1 is to demonstrate deployment of very thin multiline (and thus micrometeoroid tolerant) tether and to measure the Coulomb drag effect on the charged tether by ionospheric plasma ram flow. The Coulomb drag has not been measured before and besides useful for deorbiting the effect can also be used to propel interplanetary spacecraft by the fast moving solar wind plasma stream. The measurement of the micronewton scale force is carried out by turning the voltage on and off in a synchronous way with the satellite's rotation and by measuring the cumulative change in the rotation rate over many spin periods. In the presentation we will give the latest update of the ESTCube-1 project as well as its follow-up Aalto-1 satellite mission.

Condensation on a noncollapsing vapor bubble in a subcooled liquid

NASA Technical Reports Server (NTRS)

Baumeister, K. J.; Simoneau, R. J.

1979-01-01

An experimental procedure is presented by which an estimate can be made of the condensation coefficient on a noncollapsing stationary vapor bubble in subcooled liquid nitrogen. Film boiling from a thin wire was used to generate vapor bubbles which remain fixed to the wire at their base. A balance was established between the evaporation in the thin annular region along the wire and the condensation in the vapor bubbles.

Process for producing fine and ultrafine filament superconductor wire

DOEpatents

Kanithi, H.C.

1992-02-18

A process for producing a superconductor wire made up of a large number of round monofilament rods is provided for, comprising assembling a multiplicity of round monofilaments inside each of a multiplicity of thin wall hexagonal tubes and then assembling a number of said thin wall hexagonal tubes within an extrusion can and subsequently consolidating, extruding and drawing the entire assembly down to the desired wire size. 8 figs.

Process for producing fine and ultrafine filament superconductor wire

DOEpatents

Kanithi, Hem C.

1992-01-01

A process for producing a superconductor wire made up of a large number of round monofilament rods is provided for, comprising assembling a multiplicity of round monofilaments inside each of a multiplicity of thin wall hexagonal tubes and then assembling a number of said thin wall hexagonal tubes within an extrusion can and subsequently consolidating, extruding and drawing the entire assembly down to the desired wire size.

Computer program for thin-wire structures in a homogeneous conducting medium

NASA Technical Reports Server (NTRS)

Richmond, J. H.

1974-01-01

A computer program is presented for thin-wire antennas and scatters in a homogeneous conducting medium. The anaylsis is performed in the real or complex frequency domain. The program handles insulated and bare wires with finite conductivity and lumped loads. The output data includes the current distribution, impedance, radiation efficiency, gain, absorption cross section, scattering cross section, echo area and the polarization scattering matrix. The program uses sinusoidal bases and Galerkin's method.

Study on the shrinkage behavior and conductivity of silver microwires during electrostatic field assisted sintering

NASA Astrophysics Data System (ADS)

Shangguan, Lei; Ma, Liuhong; Li, Mengke; Peng, Wei; Zhong, Yinghui; Su, Yufeng; Duan, Zhiyong

2018-05-01

An electrostatic field was applied to sintering Ag microwires to achieve a more compact structure and better conductivity. The shrinkage behavior of Ag microwires shows anisotropy, since bigger particle sizes, less micropores and smoother surfaces were observed in the direction of the electrostatic field in comparsion with the direction perpendicular to the electrostatic field, and the shrinkage rate of Ag microwires in the direction of electrostatic field improves about 2.4% with the electrostatic field intensity of 800 V cm‑1. The electrostatic field assisted sintering model of Ag microwires is proposed according to thermal diffuse dynamics analysis and experimental research. Moreover, the grain size of Ag microwres sintered with electrostatic field increases with the electrostatic field intensity and reaches 113 nm when the electrostatic field intensity is 800 V cm‑1, and the resistivity decreases to 2.07  ×  10‑8 Ω m as well. This method may overcome the restriction of metal wires which fabricated by the pseudoplastic metal nanoparticle fluid and be used as interconnects in nanoimprint lithography.

Obstacle Detection Algorithms for Rotorcraft Navigation

NASA Technical Reports Server (NTRS)

Kasturi, Rangachar; Camps, Octavia I.; Huang, Ying; Narasimhamurthy, Anand; Pande, Nitin; Ahumada, Albert (Technical Monitor)

2001-01-01

In this research we addressed the problem of obstacle detection for low altitude rotorcraft flight. In particular, the problem of detecting thin wires in the presence of image clutter and noise was studied. Wires present a serious hazard to rotorcrafts. Since they are very thin, their detection early enough so that the pilot has enough time to take evasive action is difficult, as their images can be less than one or two pixels wide. After reviewing the line detection literature, an algorithm for sub-pixel edge detection proposed by Steger was identified as having good potential to solve the considered task. The algorithm was tested using a set of images synthetically generated by combining real outdoor images with computer generated wire images. The performance of the algorithm was evaluated both, at the pixel and the wire levels. It was observed that the algorithm performs well, provided that the wires are not too thin (or distant) and that some post processing is performed to remove false alarms due to clutter.

Pressure Measurements for Tungsten Wire Explosions in Water

NASA Astrophysics Data System (ADS)

Afanas'ev, V. N.

2005-07-01

Successful wire array implosion experiments carried out on PBFA- Z accelerator [1], in which a record-breaking soft x-ray yield of more than 1.5 MJ was observed, stimulated interest in research of electric explosion of thin metal wires. The results of pressure measurements micron's tungsten wire explosion, which carried out in deionized water. Thin tungsten wire explosion was investigated experimentally at current pulse 100 ns duration. The shock waves from the 70 μm tungsten wire explosion were measured by the piezoceramic pressure gauge. The gauges were placed at a range from 3 to 15 mm of wire. The piezoceramic gauges were calibrated on the stable electron beams generator with nanoseconds duration. Experiments were carried out for verifying the tungsten plasma equation of state parameters under different values of the deposited energy. [1] R. B. Spielman, C. Deeney, G. A. Chandler et al., Phys.Plasmas #5, ð. 2105, 1998. The work was supported by ISTC # 1826

Metal organic vapour-phase epitaxy growth of GaN wires on Si (111) for light-emitting diode applications

PubMed Central

2013-01-01

GaN wires are grown on a Si (111) substrate by metal organic vapour-phase epitaxy on a thin deposited AlN blanket and through a thin SiNx layer formed spontaneously at the AlN/Si interface. N-doped wires are used as templates for the growth of core-shell InGaN/GaN multiple quantum wells coated by a p-doped shell. Standing single-wire heterostructures are connected using a metallic tip and a Si substrate backside contact, and the electroluminescence at room temperature and forward bias is demonstrated at 420 nm. This result points out the feasibility of lower cost nitride-based wires for light-emitting diode applications. PMID:23391377

Implications of possible shuttle charging. [prediction analysis techniques for insulation and electrical grounding against ionospheric conductivity

NASA Technical Reports Server (NTRS)

Taylor, W. W. L.

1979-01-01

Shuttle charging is discussed and two analyses of shuttle charging are performed. The first predicts the effective collecting area of a wire grid, biased with the respect to the potential of the magnetoplasma surrounding it. The second predicts the intensity of broadband electromagnetic noise that is emitted when surface electrostatic discharges occur between the beta cloth and the wire grid sewn on it.

Welding Wires To Thin Thermocouple Films

NASA Technical Reports Server (NTRS)

Holanda, Raymond; Kim, Walter S.; Danzey, Gerald A.; Pencil, Eric; Wadel, Mary

1993-01-01

Parallel-gap resistance welding yields joints surviving temperatures of about 1,000 degrees C. Much faster than thermocompression bonding. Also exceeds conductive-paste bonding and sputtering thin films through porous flame-sprayed insulation on prewelded lead wires. Introduces no foreign material into thermocouple circuit and does not require careful control of thickness of flame-sprayed material.

Antibacterial effect of visible light reactive TiO2/Ag nanocomposite thin film on the orthodontic appliances.

PubMed

Yun, Kwidug; Oh, Gyejeong; Vang, Mongsook; Yang, Hongso; Lim, Hyunpil; Koh, Jeongtae; Jeong, Woonjo; Yoon, Dongjoo; Lee, Kyungku; Lee, Kwangmin; Park, Sangwon

2011-08-01

This study evaluated the antibacterial effect of a visible light reactive TiO2/Ag nanocomposite thin film on dental orthodontic wire (STS 304 wire). The growth of S. mutans and A. actinomycetemcomitans was suppressed on the specimens coated with TiO2/Ag compared to the uncoated specimens. The antibacterial effect of the TiO2/Ag nanocomposite thin film was improved under visible light irradiation.

Laser shape setting of superelastic nitinol wires: Functional properties and microstructure

NASA Astrophysics Data System (ADS)

Tuissi, Ausonio; Coduri, Mauro; Biffi, Carlo Alberto

Shape setting is one of the most important steps in the production route of Nitinol Shape Memory Alloys (SMAs), as it can fix the functional properties, such as the shape memory effect and the superelasticity (SE). The conventional method for making the shape setting is performed at 400-500∘C in furnaces. In this work, a laser beam was adopted for performing straight shape setting on commercially available austenitic Nitinol thin wires. The laser beam, at different power levels, was moved along the wire length for inducing the functional performances. Calorimetric, pseudo-elastic and microstructural features of the laser annealed wires were studied through differential scanning calorimetry, tensile testing and high energy X-ray diffraction, respectively. It can be stated that the laser technology can induce SE in thin Nitinol wires: the wire performances can be modulated in function of the laser power and improved functional properties can be obtained.

Numerical analysis of transient fields near thin-wire antennas and scatterers

NASA Astrophysics Data System (ADS)

Landt, J. A.

1981-11-01

Under the premise that `accelerated charge radiates,' one would expect radiation on wire structures to occur from driving points, ends of wires, bends in wires, or locations of lumped loading. Here, this premise is investigated in a series of numerical experiments. The numerical procedure is based on a moment-method solution of a thin-wire time-domain electric-field integral equation. The fields in the vicinity of wire structures are calculated for short impulsive-type excitations, and are viewed in a series of time sequences or snapshots. For these excitations, the fields are spatially limited in the radial dimension, and expand in spheres centered about points of radiation. These centers of radiation coincide with the above list of possible source regions. Time retardation permits these observations to be made clearly in the time domain, similar to time-range gating. In addition to providing insight into transient radiation processes, these studies show that the direction of energy flow is not always defined by Poynting's vector near wire structures.

Method and apparatus for fabricating a thin-film solar cell utilizing a hot wire chemical vapor deposition technique

DOEpatents

Wang, Qi; Iwaniczko, Eugene

2006-10-17

A thin-film solar cell is provided. The thin-film solar cell comprises an a-SiGe:H (1.6 eV) n-i-p solar cell having a deposition rate of at least ten (10) .ANG./second for the a-SiGe:H intrinsic layer by hot wire chemical vapor deposition. A method for fabricating a thin film solar cell is also provided. The method comprises depositing a n-i-p layer at a deposition rate of at least ten (10) .ANG./second for the a-SiGe:H intrinsic layer.

Tungsten wire and tubing joined by nickel brazing

NASA Technical Reports Server (NTRS)

1965-01-01

Thin tungsten wire and tungsten tubing are brazed together using a contacting coil of nickel wire heated to its melting point in an inert-gas atmosphere. This method is also effective for brazing tungsten to tungsten-rhenium parts.

Electrostatic bonding of thin (approximately 3 mil) 7070 cover glass to Ta2O5 AR-coated thin (approximately 2 mil) silicon wafers and solar cells

NASA Technical Reports Server (NTRS)

Egelkrout, D. W.; Horne, W. E.

1980-01-01

Electrostatic bonding (ESB) of thin (3 mil) Corning 7070 cover glasses to Ta2O5 AR-coated thin (2 mil) silicon wafers and solar cells is investigated. An experimental program was conducted to establish the effects of variations in pressure, voltage, temperature, time, Ta2O5 thickness, and various prebond glass treatments. Flat wafers without contact grids were used to study the basic effects for bonding to semiconductor surfaces typical of solar cells. Solar cells with three different grid patterns were used to determine additional requirements caused by the raised metallic contacts.

Non-contact current and voltage sensor

DOEpatents

Carpenter, Gary D; El-Essawy, Wael; Ferreira, Alexandre Peixoto; Keller, Thomas Walter; Rubio, Juan C; Schappert, Michael A

2014-03-25

A detachable current and voltage sensor provides an isolated and convenient device to measure current passing through a conductor such as an AC branch circuit wire, as well as providing an indication of an electrostatic potential on the wire, which can be used to indicate the phase of the voltage on the wire, and optionally a magnitude of the voltage. The device includes a housing that contains the current and voltage sensors, which may be a ferrite cylinder with a hall effect sensor disposed in a gap along the circumference to measure current, or alternative a winding provided through the cylinder along its axis and a capacitive plate or wire disposed adjacent to, or within, the ferrite cylinder to provide the indication of the voltage.

Facile fabrication of wire-type indium gallium zinc oxide thin-film transistors applicable to ultrasensitive flexible sensors.

PubMed

Kim, Yeong-Gyu; Tak, Young Jun; Kim, Hee Jun; Kim, Won-Gi; Yoo, Hyukjoon; Kim, Hyun Jae

2018-04-03

We fabricated wire-type indium gallium zinc oxide (IGZO) thin-film transistors (TFTs) using a self-formed cracked template based on a lift-off process. The electrical characteristics of wire-type IGZO TFTs could be controlled by changing the width and density of IGZO wires through varying the coating conditions of template solution or multi-stacking additional layers. The fabricated wire-type devices were applied to sensors after functionalizing the surface. The wire-type pH sensor showed a sensitivity of 45.4 mV/pH, and this value was an improved sensitivity compared with that of the film-type device (27.6 mV/pH). Similarly, when the wire-type device was used as a glucose sensor, it showed more variation in electrical characteristics than the film-type device. The improved sensing properties resulted from the large surface area of the wire-type device compared with that of the film-type device. In addition, we fabricated wire-type IGZO TFTs on flexible substrates and confirmed that such structures were very resistant to mechanical stresses at a bending radius of 10 mm.

Wire winding increases lifetime of oxide coated cathodes

NASA Technical Reports Server (NTRS)

Kerslake, W.; Vargo, D.

1965-01-01

Refractory-metal heater base wound with a thin refractory metal wire increases the longevity of oxide-coated cathodes. The wire-wound unit is impregnated with the required thickness of metal oxide. This cathode is useful in magnetohydrodynamic systems and in electron tubes.

High extinction ratio and low transmission loss thin-film terahertz polarizer with a tunable bilayer metal wire-grid structure.

PubMed

Huang, Zhe; Parrott, Edward P J; Park, Hongkyu; Chan, Hau Ping; Pickwell-MacPherson, Emma

2014-02-15

A thin-film terahertz polarizer is proposed and realized via a tunable bilayer metal wire-grid structure to achieve high extinction ratios and good transmission. The polarizer is fabricated on top of a thin silica layer by standard micro-fabrication techniques to eliminate the multireflection effects. The tunable alignment of the bilayer aluminum-wire grid structure enables tailoring of the extinction ratio and transmission characteristics. Using terahertz time-domain spectroscopy (THz-TDS), a fabricated polarizer is characterized, with extinction ratios greater than 50 dB and transmission losses below 1 dB reported in the 0.2-1.1 THz frequency range. These characteristics can be improved by further tuning the polarizer parameters such as the pitch, metal film thickness, and lateral displacement.

Decomposition of poly(amide-imide) film enameled on solid copper wire using atmospheric pressure non-equilibrium plasma.

PubMed

Sugiyama, Kazuo; Suzuki, Katsunori; Kuwasima, Shusuke; Aoki, Yosuke; Yajima, Tatsuhiko

2009-01-01

The decomposition of a poly(amide-imide) thin film coated on a solid copper wire was attempted using atmospheric pressure non-equilibrium plasma. The plasma was produced by applying microwave power to an electrically conductive material in a gas mixture of argon, oxygen, and hydrogen. The poly(amide-imide) thin film was easily decomposed by argon-oxygen mixed gas plasma and an oxidized copper surface was obtained. The reduction of the oxidized surface with argon-hydrogen mixed gas plasma rapidly yielded a metallic copper surface. A continuous plasma heat-treatment process using a combination of both the argon-oxygen plasma and argon-hydrogen plasma was found to be suitable for the decomposition of the poly(amide-imide) thin film coated on the solid copper wire.

Piezoelectric and Electrostatic Polymeric Transducers for Acoustic Emission Detection.

DTIC Science & Technology

1984-12-01

the fabrication of ultrasonic transducers for acoustic emission (A.E.) detection using polyvinylidene fluoride ( PVDF ) active elements. ii) the...characterization of PVDF transducers. The second report compared the sensitivity of PVDF transducers with polypropylene electrostatic transducer...detection using polyvinylidene 1uoride ( PVDF ) active elements. ii) the fabrication of electrostatic transducers using thin film of non-polar

A Bridge between Two Important Problems in Optics and Electrostatics

ERIC Educational Resources Information Center

Capelli, R.; Pozzi, G.

2008-01-01

It is shown how the same physically appealing method can be applied to find analytic solutions for two difficult and apparently unrelated problems in optics and electrostatics. They are: (i) the diffraction of a plane wave at a perfectly conducting thin half-plane and (ii) the electrostatic field associated with a parallel array of stripes held at…

Wire Detection Algorithms for Navigation

NASA Technical Reports Server (NTRS)

Kasturi, Rangachar; Camps, Octavia I.

2002-01-01

In this research we addressed the problem of obstacle detection for low altitude rotorcraft flight. In particular, the problem of detecting thin wires in the presence of image clutter and noise was studied. Wires present a serious hazard to rotorcrafts. Since they are very thin, their detection early enough so that the pilot has enough time to take evasive action is difficult, as their images can be less than one or two pixels wide. Two approaches were explored for this purpose. The first approach involved a technique for sub-pixel edge detection and subsequent post processing, in order to reduce the false alarms. After reviewing the line detection literature, an algorithm for sub-pixel edge detection proposed by Steger was identified as having good potential to solve the considered task. The algorithm was tested using a set of images synthetically generated by combining real outdoor images with computer generated wire images. The performance of the algorithm was evaluated both, at the pixel and the wire levels. It was observed that the algorithm performs well, provided that the wires are not too thin (or distant) and that some post processing is performed to remove false alarms due to clutter. The second approach involved the use of an example-based learning scheme namely, Support Vector Machines. The purpose of this approach was to explore the feasibility of an example-based learning based approach for the task of detecting wires from their images. Support Vector Machines (SVMs) have emerged as a promising pattern classification tool and have been used in various applications. It was found that this approach is not suitable for very thin wires and of course, not suitable at all for sub-pixel thick wires. High dimensionality of the data as such does not present a major problem for SVMs. However it is desirable to have a large number of training examples especially for high dimensional data. The main difficulty in using SVMs (or any other example-based learning method) is the need for a very good set of positive and negative examples since the performance depends on the quality of the training set.

ELECTROSTATIC AIR CLEANING DEVICE AND METHOD

DOEpatents

Silverman, L.; Anderson, D.M.

1961-07-18

A method and apparatus for utilizing friction-charged particulate material from an aerosol are described. A bed of the plastic spheres is prepared, and the aerosol is passed upwardly through the bed at a rate just large enough to maintain the bed in a fluidized state wim over-all circulation of the balls. Wire members criss-crossing through the bed rub against the balls and maintain their surfaces with electrostatic charges. The particulate material in the aerosol adheres to the surfaces of the balls.

Digital Systems Validation Handbook. Volume 2

DTIC Science & Technology

1989-02-01

power. 2. A grid of wires, solid sheet, or foil. 3. A wire from circuit to grounding block or case. 4. A wire from circuit to structure. 5. Shield...RETURN. (11) 1. Structure, for power, fault, and "discrete" circuits. 2. A grid of wires, solid sheet, or foil. 3. A wire from circuit load back to...TV (14) Television TWTD (13) Thin Wire Time Domain TX (5) Transmit U.K. (13,141 United Kingdom U.S. (14) United States UART (15) Universal Asynchronous

A tool for measuring the bending length in thin wires

NASA Astrophysics Data System (ADS)

Lorenzini, M.; Cagnoli, G.; Cesarini, E.; Losurdo, G.; Martelli, F.; Piergiovanni, F.; Vetrano, F.; Viceré, A.

2013-03-01

Great effort is currently being put into the development and construction of the second generation, advanced gravitational wave detectors, Advanced Virgo and Advanced LIGO. The development of new low thermal noise suspensions of mirrors, based on the experience gained in the previous experiments, is part of this task. Quasi-monolithic suspensions with fused silica wires avoid the problem of rubbing friction introduced by steel cradle arrangements by directly welding the wires to silica blocks bonded to the mirror. Moreover, the mechanical loss level introduced by silica (ϕfs ˜ 10-7 in thin fused silica wires) is by far less than the one associated with steel. The low frequency dynamical behaviour of the suspension can be computed and optimized, provided that the wire bending shape under pendulum motion is known. Due to the production process, fused silica wires are thicker near the two ends (necks), so that analytical bending computations are very complicated. We developed a tool to directly measure the low frequency bending parameters of fused silica wires, and we tested it on the wires produced for the Virgo+ monolithic suspensions. The working principle and a set of test measurements are presented and explained.

A tool for measuring the bending length in thin wires.

PubMed

Lorenzini, M; Cagnoli, G; Cesarini, E; Losurdo, G; Martelli, F; Piergiovanni, F; Vetrano, F; Viceré, A

2013-03-01

Great effort is currently being put into the development and construction of the second generation, advanced gravitational wave detectors, Advanced Virgo and Advanced LIGO. The development of new low thermal noise suspensions of mirrors, based on the experience gained in the previous experiments, is part of this task. Quasi-monolithic suspensions with fused silica wires avoid the problem of rubbing friction introduced by steel cradle arrangements by directly welding the wires to silica blocks bonded to the mirror. Moreover, the mechanical loss level introduced by silica (φfs ∼ 10(-7) in thin fused silica wires) is by far less than the one associated with steel. The low frequency dynamical behaviour of the suspension can be computed and optimized, provided that the wire bending shape under pendulum motion is known. Due to the production process, fused silica wires are thicker near the two ends (necks), so that analytical bending computations are very complicated. We developed a tool to directly measure the low frequency bending parameters of fused silica wires, and we tested it on the wires produced for the Virgo+ monolithic suspensions. The working principle and a set of test measurements are presented and explained.

LABORATORY ANALYSIS OF BACK-CORONA DISCHARGE

EPA Science Inventory

The paper discusses an experimental research program to characterize back-corona generation and behavior in a range of environments and geometries common to electrostatic precipitators (ESPs). A wire-parallel plate device was used to monitor the intensity and distribution of back...

THEORETICAL METHODS FOR COMPUTING ELECTRICAL CONDITIONS IN WIRE-PLATE ELECTROSTATIC PRECIPITATORS

EPA Science Inventory

The paper describes a new semi-empirical, approximate theory for predicting electrical conditions. In the approximate theory, analytical expressions are derived for calculating voltage-current characteristics and electric potential, electric field, and space charge density distri...

Non-contact current and voltage sensor having detachable housing incorporating multiple ferrite cylinder portions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carpenter, Gary D.; El-Essawy, Wael; Ferreira, Alexandre Peixoto

2016-04-26

A detachable current and voltage sensor provides an isolated and convenient device to measure current passing through a conductor such as an AC branch circuit wire, as well as providing an indication of an electrostatic potential on the wire, which can be used to indicate the phase of the voltage on the wire, and optionally a magnitude of the voltage. The device includes a housing formed from two portions that mechanically close around the wire and that contain the current and voltage sensors. The current sensor is a ferrite cylinder formed from at least three portions that form the cylindermore » when the sensor is closed around the wire with a hall effect sensor disposed in a gap between two of the ferrite portions along the circumference to measure current. A capacitive plate or wire is disposed adjacent to, or within, the ferrite cylinder to provide the indication of the voltage.« less

A modal radar cross section of thin-wire targets via the singularity expansion method

NASA Technical Reports Server (NTRS)

Richards, M. A.; Shumpert, T. H.; Riggs, L. S.

1992-01-01

A modal radar cross section (RCS) of arbitrary wire scatterers is constructed in terms of SEM parameters. Numerical results are presented for both straight and L-shaped wire targets and are compared to computations performed in the frequency domain using the method of moments.

Computer Program for Thin Wire Antenna over a Perfectly Conducting Ground Plane. [using Galerkins method and sinusoidal bases

NASA Technical Reports Server (NTRS)

Richmond, J. H.

1974-01-01

A computer program is presented for a thin-wire antenna over a perfect ground plane. The analysis is performed in the frequency domain, and the exterior medium is free space. The antenna may have finite conductivity and lumped loads. The output data includes the current distribution, impedance, radiation efficiency, and gain. The program uses sinusoidal bases and Galerkin's method.

Thin metal electrode for AMTEC

NASA Technical Reports Server (NTRS)

Williams, Roger M. (Inventor); Wheeler, Bob L. (Inventor); Jefferies-Nakamura, Barbara (Inventor); Lamb, James L. (Inventor); Bankston, C. Perry (Inventor); Cole, Terry (Inventor)

1989-01-01

An electrode having higher power output is formed of a thin, porous film (less than 1 micrometer) applied to a beta-alumina solid electrolyte (BASE). The electrode includes an open grid, current collector such as a series of thin, parallel, grid lines applied to the thin film and a plurality of cross-members such as loop of metal wire surrounding the BASE tube. The loops are electrically connected by a bus wire. The overall impedance of the electrode considering both the contributions from the bulk BASE and the porous electrode BASE interface is low, about 0.5 OHM/cm.sup.2 and power densities of over 0.3 watt/cm.sup.2 for extended periods.

Method for fabricating thin californium-containing radioactive source wires

DOEpatents

Gross, Ian G; Pierce, Larry A

2006-08-22

A method for reducing the cross-sectional diameter of a radioactive californium-containing cermet wire while simultaneously improving the wire diameter to a more nearly circular cross section. A collet fixture is used to reduce the wire diameter by controlled pressurization pulses while simultaneously improving the wire cross-sectional diameter. The method is especially suitable for use in hot cells for the production of optimized cermet brachytherapy sources that contain large amounts of radioactive californium-252.

Standard surface grinder for precision machining of thin-wall tubing

NASA Technical Reports Server (NTRS)

Jones, A.; Kotora, J., Jr.; Rein, J.; Smith, S. V.; Strack, D.; Stuckey, D.

1967-01-01

Standard surface grinder performs precision machining of thin-wall stainless steel tubing by electrical discharge grinding. A related adaptation, a traveling wire electrode fixture, is used for machining slots in thin-walled tubing.

Geometrical Effects in Noise Spectra of Superconducting Flux Qubits

NASA Astrophysics Data System (ADS)

Petukhov, Andre; Smelyanskiy, Vadim; Martinis, John

We present theoretical study of geometrical effects related to spin diffusion in superconducting flux qubits. We adopt a model of a long superconducting wire surrounded by a thin oxide layer with spins distributed uniformly over cross-sectional area of the oxide layer. Using a continuous transformation from a round cylinder to a flat wire strip, we demonstrate that the noise spectral density tends to a power law S (ω) ~(ω / Γ) - s with s 3 / 4 , approaching s = 3 / 4 for very thin wires. The ω-s dependence is valid in a broad frequency range above ωΓ stretching up to four orders of magnitude in units of characteristic diffusion decay rate Γ ~ 1 -102 Hz. The effect is highly sensitive to a cross-sectional aspect ratio of a thin wire thus revealing its geometrical origin. We substantiate our findings by detailed comparison with available experimental data and conclude that 3 / 4 power law distinguishes spin diffusion flux noise from generic `` 1 / f '' family. Supported by the AFRL Information Directorate under Grant F4HBKC4162G001.

Non-contact current and voltage sensing method using a clamshell housing and a ferrite cylinder

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carpenter, Gary D.; El-Essawy, Wael; Ferreira, Alexandre Peixoto

2016-04-26

A method of measurement using a detachable current and voltage sensor provides an isolated and convenient technique for to measuring current passing through a conductor such as an AC branch circuit wire, as well as providing an indication of an electrostatic potential on the wire, which can be used to indicate the phase of the voltage on the wire, and optionally a magnitude of the voltage. The device includes a housing that contains the current and voltage sensors, which may be a ferrite cylinder with a hall effect sensor disposed in a gap along the circumference to measure current, ormore » alternative a winding provided through the cylinder along its axis and a capacitive plate or wire disposed adjacent to, or within, the ferrite cylinder to provide the indication of the voltage.« less

Ultrasonic Guided Waves for Aging Wire Insulation Assessment

NASA Technical Reports Server (NTRS)

Anastasi, Robert F.; Madaras, Eric I.

2001-01-01

Environmentally aged wire insulation can become brittle and crack and thus expose the underlying conductive wire to the potential for short circuits and fire. The feasibility of using ultrasonic guided waves to measure insulation condition was examined. First a simple model to study guided wave propagation in a bare and thin plastic coated wire was examined and then some aviation grade wire samples that had been heat-damaged. Initial measurements indicate that ultrasonic guided wave velocity can be used to monitor insulation stiffness.

Integrated Electrical Wire Insulation Repair System

NASA Technical Reports Server (NTRS)

Williams, Martha; Jolley, Scott; Gibson, Tracy; Parks, Steven

2013-01-01

An integrated system tool will allow a technician to easily and quickly repair damaged high-performance electrical wire insulation in the field. Low-melt polyimides have been developed that can be processed into thin films that work well in the repair of damaged polyimide or fluoropolymer insulated electrical wiring. Such thin films can be used in wire insulation repairs by affixing a film of this low-melt polyimide to the damaged wire, and heating the film to effect melting, flow, and cure of the film. The resulting repair is robust, lightweight, and small in volume. The heating of this repair film is accomplished with the use of a common electrical soldering tool that has been modified with a special head or tip that can accommodate the size of wire being repaired. This repair method can furthermore be simplified for the repair technician by providing replaceable or disposable soldering tool heads that have repair film already "loaded" and ready for use. The soldering tool heating device can also be equipped with a battery power supply that will allow its use in areas where plug-in current is not available

EFFECTS OF TURBULENCE AND ELECTROHYDRODYAMICS ON THE PERFORMANCE OF ELECTROSTATIC PRECIPITATORS

EPA Science Inventory

Numerical simulations of the turbulent diffusion equation coupled with the electrohydrodynamics (EHD) are carried out for the plate-plate and wire-plate ESPs. The local particle concentration profiles and fractional collection efficiencies have been evaluated as a function of thr...

ADVANCED ELECTROSTATIC ENHANCEMENT OF FABRIC FILTRATION

EPA Science Inventory

The paper discusses laboratory and pilot plant studies of a modification of the U.S. EPA's Electrically Stimulated Fabric Filtration (ESFF) method in which corona voltage on a center-wire electrode replaces the subcorona electrodes at the bag surface. The electric field which aff...

Polarization-dependent thin-film wire-grid reflectarray for terahertz waves

DOE Office of Scientific and Technical Information (OSTI.GOV)

Niu, Tiaoming; School of Information Science and Engineering, Lanzhou University, Lanzhou 730000; Upadhyay, Aditi

2015-07-20

A thin-film polarization-dependent reflectarray based on patterned metallic wire grids is realized at 1 THz. Unlike conventional reflectarrays with resonant elements and a solid metal ground, parallel narrow metal strips with uniform spacing are employed in this design to construct both the radiation elements and the ground plane. For each radiation element, a certain number of thin strips with an identical length are grouped to effectively form a patch resonator with equivalent performance. The ground plane is made of continuous metallic strips, similar to conventional wire-grid polarizers. The structure can deflect incident waves with the polarization parallel to the stripsmore » into a designed direction and transmit the orthogonal polarization component. Measured radiation patterns show reasonable deflection efficiency and high polarization discrimination. Utilizing this flexible device approach, similar reflectarray designs can be realized for conformal mounting onto surfaces of cylindrical or spherical devices for terahertz imaging and communications.« less

Technology of Producing the Contact Connections of Superconductor Metal-Sheathed Cable

NASA Astrophysics Data System (ADS)

Jakubowski, Andrzej

2017-06-01

The technology of producing the current contact connections on the superconductor cable edges is presented. This lead cable is used as one of the major elements of the magnetic system in thermonuclear reactor construction, actuality for modern world energy. The technology is realized by the radial draft of metal thin-walled tube on the conductor's package. The filling of various profiles by round section wire is optimized. Geometrical characteristics of the dangerous crosssection (as a broken ring) of thin-walled tube injured by the sector cut-out are accounted. The comparative strength calculation of the solid and injured tubes at a longitudinal compression and lateral bending is acted. The radial draft mechanism of cylindrical thin-walled sheath with the wire packing is designed. The necessity to use the nonlinear theory for the sheaths calculate is set. The resilient co-operation of wires as the parallel located cylinders with the contact stripes of rectangular form is considered.

Shape memory alloy wires turn composites into smart structures: I. Material requirements

NASA Astrophysics Data System (ADS)

Schrooten, Jan; Michaud, Veronique J.; Zheng, Yanjun; Balta-Neumann, J. Antonio; Manson, Jan-Anders E.

2002-07-01

Composites containing thin Shape Memory Alloy (SMA) wires show great potential as materials able to adapt their shape, thermal behavior or vibrational properties to external stimuli. The functional properties of SMA-composites are directly related to the constraining effect of the matrix on the reversible martensitic transformation of the embedded pre-strained SMA wires. The present work reports results of a concerted European effort towards a fundamental understanding of the manufacturing and design of SMA composites. This first part investigates the transformational behavior of constrained SMA wires and its translation into functional properties of SMA composites. Thermodynamic and thermomechanical experiments were performed on SMA wires. A model was developed to simulate the thermomechanical behavior of the wires. From the screening of potential wires it was concluded that NiTiCu, as well as R-phase NiTi appeared as best candidates. Requirements for the host composite materials were surveyed. A Kevlar-epoxy system was chosen. Finally, the quality of the SMA wire-resin interface was assessed by two different techniques. These indicated that a thin oxide layer seems to provide the best interfacial strength. A temperature window in which SMA composites can be safely used was also defined. The manufacturing and properties of the SMA composites will be discussed in Part II.

A Novel Method of Coating Orthodontic Archwires with Nanoparticles

PubMed Central

Syed, Shibli S; Kulkarni, Dinraj; Todkar, Rohit; Bagul, Ravikiran S; Parekh, Kreena; Bhujbal, Nikita

2015-01-01

Background: The major hazard to the orthodontic tooth movement is the friction developing at the bracket wire interface. In the past, there have been various attempts to reduce this friction. We believe that coating the commercially available orthodontic wires with nanoparticles can result in a successful reduction of this friction. The objective of this study is to develop a novel method of coating orthodontic archwires with nanoparticles. Materials and Methods: Stainless steel (Ormco, CA, USA), titanium molybdenum alloy (Ormco, CA, USA) and nickel-titanium (G and H Wire Company, USA) orthodontic wires with a rectangular cross-section dimension of 0.019”× 0.025”, were selected. The wires were later coated with a uniform and smooth nanoparticle film using 100 ml nanocremics. The coating procedure described in this article is a sol-gel thin film dip coating method. Results: The coating procedure was verified by comparing the surface topography of nanocoated archwires with the commercially available archwires in an environmental scanning electron microscope (ESEM). The ESEM images prove that the surface topography of the coated wires was found to be smoother with less surface deteriorations as compared to the commercially available wires. Conclusion: Commercially available orthodontic wires can be successfully coated using a novel method of sol-gel thin film dip coating method. PMID:26028899

Findings from NASA's 2015-2017 Electric Sail Investigations

NASA Technical Reports Server (NTRS)

Wiegmann, Bruce. M.

2017-01-01

Electric Sail (E-Sail) propulsion systems will enable scientific spacecraft to obtain velocities of up to 10 astronomical units per year without expending any on-board propellant. The E-Sail propulsion is created from the interaction of a spacecraft's positively charged multi-kilometer-length conductor/s with protons that are present in the naturally occurring hypersonic solar wind. The protons are deflected via natural electrostatic repulsion forces from the Debye sheath that is formed around a charged wire in space, and this deflection of protons creates thrust or propulsion in the opposite direction. It is envisioned that this E-Sail propulsion system can provide propulsion throughout the solar system and to the heliosphere and beyond. Consistent with the concept of a "sail," no propellant is needed as electrostatic repulsion interactions between the naturally occurring solar wind protons and a positively charged wire creates the propulsion. The basic principle on which the Electric Sail operates is the exchange of momentum between an "electric sail" and solar wind, which continually flows radially away from the sun at speeds ranging from 300 to 700 kilometers per second. The "sail" consists of an array of long, charged wires which extend radially outward 10 to 30 kilometers from a slowly rotating spacecraft. Momentum is transferred from the solar wind to the array through the deflection of the positively charged solar wind protons by a high voltage potential applied to the wires. The thrust generated by an E-Sail is proportional to the area of the sail, which is given by the product of the total length of the wires and the effective wire diameter. The wire is approximately 0.1 millimeters in diameter. However, the effective diameter is determined by the distance the applied electric potential penetrates into space around the wire (on the order of 10 meters at 1 astronomical unit). As a result, the effective area over which protons are repelled is proportional to the size of the region of electric potential, or the plasma sheath region, surround the wires of the array. A large sheath is, therefore, beneficial to the generation of thrust. However, this benefit must be balanced with the additional fact that electron collection is proportional to sheath size. Electrons collected by the wire array must be injected back into the solar wind in order to maintain the potential on the wires - which requires power. The primary power requirement for E-Sail operation is, therefore, also proportional to sheath size.

Interfacial Microstructure and Its Influence on Resistivity of Thin Layers Copper Cladding Steel Wires

NASA Astrophysics Data System (ADS)

Li, Hongjuan; Ding, Zhimin; Zhao, Ruirong

2018-04-01

The interfacial microstructure and resistivity of cold-drawn and annealed thin layers copper cladding steel (CCS) wires have been systematically investigated by the methods of scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), and resistivity testing. The results showed that the Cu and Fe atoms near interface diffused into each other matrixes. The Fe atoms diffused into Cu matrixes and formed a solid solution. The mechanism of solid solution is of substitution type. When the quantity of Fe atoms exceeds the maximum solubility, the supersaturated solid solution would form Fe clusters and decompose into base Cu and α-Fe precipitated phases under certain conditions. A few of α-Fe precipitates was observed in the copper near Cu/Fe interfaces of cold-drawn CCS wires, with 1-5 nm in size. A number of α-Fe precipitates of 1-20 nm in size can be detected in copper near Cu/Fe interfaces of CCS wires annealed at 850°C. When annealing temperature was less than 750°C, the resistivity of CCS wires annealed was lower than that of cold-drawn CCS wires. However, when annealing temperature was above 750°C, the resistivity of CCS wires was greater than that of cold-drawn CCS wires and increased with rising the annealing temperature. The relationship between nanoscale α-Fe precipitation and resistivity of CCS wires has been well discussed.

Equilibrium charge distribution on a finite straight one-dimensional wire

NASA Astrophysics Data System (ADS)

Batle, Josep; Ciftja, Orion; Abdalla, Soliman; Elhoseny, Mohamed; Alkhambashi, Majid; Farouk, Ahmed

2017-09-01

The electrostatic properties of uniformly charged regular bodies are prominently discussed on college-level electromagnetism courses. However, one of the most basic problems of electrostatics that deals with how a continuous charge distribution reaches equilibrium is rarely mentioned at this level. In this work we revisit the problem of equilibrium charge distribution on a straight one-dimensional (1D) wire with finite length. The majority of existing treatments in the literature deal with the 1D wire as a limiting case of a higher-dimensional structure that can be treated analytically for a Coulomb interaction potential between point charges. Surprisingly, different models (for instance, an ellipsoid or a cylinder model) may lead to different results, thus there is even some ambiguity on whether the problem is well-posed. In this work we adopt a different approach where we do not start with any higher-dimensional body that reduces to a 1D wire in the appropriate limit. Instead, our starting point is the obvious one, a finite straight 1D wire that contains charge. However, the new tweak in the model is the assumption that point charges interact with each other via a non-Coulomb power-law interaction potential. This potential is well-behaved, allows exact analytical results and approaches the standard Coulomb interaction potential as a limit. The results originating from this approach suggest that the equilibrium charge distribution for a finite straight 1D wire is a uniform charge density when the power-law interaction potential approaches the Coulomb interaction potential as a suitable limit. We contrast such a finding to results obtained using a different regularised logarithmic interaction potential which allows exact treatment in 1D. The present self-contained material may be of interest to instructors teaching electromagnetism as well as students who will discover that simple-looking problems may sometimes pose important scientific challenges.

ESD Test Apparatus for Soldering Irons

NASA Technical Reports Server (NTRS)

Sancho, Jose; Esser, Robert

2013-01-01

ESDA (Electrostatic Discharge Association) ESD STM 13.1-2000 requires frequent testing of the voltage leakage from the tip of a soldering iron and the resistance from the tip of the soldering iron to the common point ground. Without this test apparatus, the process is time-consuming and requires several wires, alligator clips, or test probes, as well as additional equipment. Soldering iron tips must be tested for electrostatic discharge risks frequently, and this typically takes a lot of time in setup and testing. This device enables the operator to execute the full test in one minute or less. This innovation is a simple apparatus that plugs into a digital multimeter (DMM) and the Common Point Ground (CPG) reference. It enables the user to perform two of the electrostatic discharge tests required in ESD STM 13.1-2000. The device consists of a small black box with two prongs sticking out of one end, two inputs on the opposite end (one of the inputs is used to connect the reference CPG to the DMM), and a metal tab on one side. Inside the box are wires, several washers of various materials, and assembly hardware (nuts and screws/bolts). The device is a passive electronic component that is plugged into a DMM. The operator sets the DMM to read voltage. The operator places the heated tip of the soldering iron onto the metal tab with a small amount of solder to ensure a complete connection. The voltage is read and recorded. The operator switches the DMM to read resistance. The operator places the heated tip of the soldering iron onto the metal tab with a small amount of solder to ensure a complete connection. The resistance is recorded. If the recorded voltage and resistance are below a number stated in ESDA ESD STM 13.1-2000, the test is considered to pass. The device includes all the necessary wiring internal to its body so the operator does not need to do any independent wiring, except for grounding. It uses a stack of high-thermal-resistance washers to minimize the heat transfer from the soldering iron to the wiring used to measure the resistance and voltages. This minimizes thermal error. The device allows very rapid execution of a test that is performed frequently.

John F. Kennedy Space Center's Technology Development and Application 2006-2007 Report

NASA Technical Reports Server (NTRS)

2008-01-01

Topics covered include: Reversible Chemochromic Hydrogen Detectors; Determining Trajectory of Triboelectrically Charged Particles, Using Discrete Element Modeling; Using Indium Tin Oxide To Mitigate Dust on Viewing Ports; High-Performance Polyimide Powder Coatings; Controlled-Release Microcapsules for Smart Coatings for Corrosion Applications; Aerocoat 7 Replacement Coatings; Photocatalytic Coatings for Exploration and Spaceport Design; New Materials for the Repair of Polyimide Electrical Wire Insulation; Commodity-Free Calibration; Novel Ice Mitigation Methods; Crack Offset Measurement With the Projected Laser Target Device; New Materials for Structural Composites and Protective Coatings; Fire Chemistry Testing of Spray-On Foam Insulation (SOFI); Using Aerogel-Based Insulation Material To Prevent Foam Loss on the Liquid-Hydrogen Intertank; Particle Ejection and Levitation Technology (PELT); Electrostatic Characterization of Lunar Dust; Numerical Analysis of Rocket Exhaust Cratering; RESOLVE Projects: Lunar Water Resource Demonstration and Regolith Volatile Characterization; Tribocharging Lunar Soil for Electrostatic Beneficiation; Numerically Modeling the Erosion of Lunar Soil by Rocket Exhaust Plumes; Trajectory Model of Lunar Dust Particles; Using Lunar Module Shadows To Scale the Effects of Rocket Exhaust Plumes; Predicting the Acoustic Environment Induced by the Launch of the Ares I Vehicle; Measuring Ultrasonic Acoustic Velocity in a Thin Sheet of Graphite Epoxy Composite; Hail Size Distribution Mapping; Launch Pad 39 Hail Monitor Array System; Autonomous Flight Safety System - Phase III; The Photogrammetry Cube; Bird Vision System; Automating Range Surveillance Through Radio Interferometry and Field Strength Mapping Techniques; Next-Generation Telemetry Workstation; GPS Metric Tracking Unit; and Space-Based Range.

Workmanship Training Industry

NASA Technical Reports Server (NTRS)

Patterson, Ashley; Sikes, Larry; Corbin, Cheryl; Rucka, Rebecca

2015-01-01

Special processes require special skills, knowledge and experienced application. For over 15 years, the NASA Johnson Space Center's Receiving, Inspection and Test Facility (RITF) has provided Workmanship Standards compliance training, issuing more than 500 to 800 training completion certificates annually. It is critical that technicians and inspectors are trained and that they maintain their proficiency to implement the applicable standards and specifications. Training services include 'hands-on' training to engineers, technicians, and inspectors in the areas of electrostatic discharge (ESD), soldering, fiber optics, lithium battery handling, torque and wire safety, and wire wrapping.

OZONE GENERATION IN DC-ENERGIZED ELECTROSTATIC PRECIPATORS

EPA Science Inventory

Ozone emissions from a short wire-plate precipitator and three commercial electronic air cleaners were measured. Ozone generation was most strongly affected by the corona current and polarity of the discharge electrode. To a lesser extent, the type of corona (i.e. whether tuft or...

Wire Test Grip Fixture

NASA Technical Reports Server (NTRS)

Burke, Christopher S.

2011-01-01

Wire-testing issues, such as the gripping strains imposed on the wire, play a critical role in obtaining clean data. In a standard test frame fitted with flat wedge grips, the gripping action alone creates stresses on the wire specimen that cause the wire to fail at the grip location. A new test frame, which is outfitted with a vacuum chamber, negated the use of any conventional commercially available wire test fixtures, as only 7 in. (17.8 cm) existed between the grip faces. An innovative grip fixture was designed to test thin gauge wire for a variety of applications in an existing Instron test frame outfitted with a vacuum chamber.

A Review of Gas-Cooled Reactor Concepts for SDI Applications

DTIC Science & Technology

1989-08-01

710 program .) Wire- Core Reactor (proposed by Rockwell). The wire- core reactor utilizes thin fuel wires woven between spacer wires to form an open...reactor is based on results of developmental studies of nuclear rocket propulsion systems. The reactor core is made up of annular fuel assemblies of...XE Addendum to Volume II. NERVA Fuel Development , Westinghouse Astronuclear Laboratory, TNR-230, July 15’ 1972. J I8- Rover Program Reactor Tests

Reliability Criteria for Thick Bonding Wire.

PubMed

Dagdelen, Turker; Abdel-Rahman, Eihab; Yavuz, Mustafa

2018-04-17

Bonding wire is one of the main interconnection techniques. Thick bonding wire is widely used in power modules and other high power applications. This study examined the case for extending the use of traditional thin wire reliability criteria, namely wire flexure and aspect ratio, to thick wires. Eleven aluminum (Al) and aluminum coated copper (CucorAl) wire samples with diameter 300 μm were tested experimentally. The wire response was measured using a novel non-contact method. High fidelity FEM models of the wire were developed and validated. We found that wire flexure is not correlated to its stress state or fatigue life. On the other hand, aspect ratio is a consistent criterion of thick wire fatigue life. Increasing the wire aspect ratio lowers its critical stress and increases its fatigue life. Moreover, we found that CucorAl wire has superior performance and longer fatigue life than Al wire.

Reliability Criteria for Thick Bonding Wire

PubMed Central

Yavuz, Mustafa

2018-01-01

Bonding wire is one of the main interconnection techniques. Thick bonding wire is widely used in power modules and other high power applications. This study examined the case for extending the use of traditional thin wire reliability criteria, namely wire flexure and aspect ratio, to thick wires. Eleven aluminum (Al) and aluminum coated copper (CucorAl) wire samples with diameter 300 μm were tested experimentally. The wire response was measured using a novel non-contact method. High fidelity FEM models of the wire were developed and validated. We found that wire flexure is not correlated to its stress state or fatigue life. On the other hand, aspect ratio is a consistent criterion of thick wire fatigue life. Increasing the wire aspect ratio lowers its critical stress and increases its fatigue life. Moreover, we found that CucorAl wire has superior performance and longer fatigue life than Al wire. PMID:29673194

High reliability bond program using small diameter aluminum wire

NASA Technical Reports Server (NTRS)

Macha, M.; Thiel, R. A.

1975-01-01

The program was undertaken to characterize the performance of small diameter aluminum wire ultrasonically bonded to conductors commonly encountered in hybrid assemblies, and to recommend guidelines for improving this performance. Wire, 25.4, 38.1 and 50.8 um (1, 1.5 and 2 mil), was used with bonding metallization consisting of thick film gold, thin film gold and aluminum as well as conventional aluminum pads on semiconductor chips. The chief tool for evaluating the performance was the double bond pull test in conjunction with a 72 hour - 150 C heat soak and -65 C to +150 C thermal cycling. In practice the thermal cycling was found to have relatively little effect compared to the heat soak. Pull strength will decrease after heat soak as a result of annealing of the aluminum wire; when bonded to thick film gold, the pull strength decreased by about 50% (weakening of the bond interface was the major cause of the reduction). Bonds to thin film gold lost about 30 - 40% of their initial pull strenth; weakening of the wire itself at the bond heel was the predominant cause. Bonds to aluminum substrate metallization lost only about 22%. Bonds between thick and thin film gold substrate metallization and semiconductor chips substantiated the previous conclusions but also showed that in about 20 to 25% of the cases, bond interface failure occurred at the semiconductor chip.

HIGH RESISTIVITY BEHAVIOR OF HOT-SIDE ELECTROSTATIC PRECIPITATORS

EPA Science Inventory

The report gives results of experiments to explain the high resistivity behavior of hot-side electrostatic precipitators (ESPs) collecting fly ash. The working hypothesis is that the behavior is the result of the buildup of a thin layer of sodium-ion-depleted fly ash which has a ...

Effect of sheath material and reaction overpressure on Ag protrusions into the TiO2 insulation coating of Bi-2212 round wire

NASA Astrophysics Data System (ADS)

Hossain, I.; Jiang, J.; Matras, M.; Trociewitz, U. P.; Lu, J.; Kametani, F.; Larbalestier, D.; Hellstrom, E.

2017-12-01

In order to develop a high current density in coils, Bi-2212 wires must be electrically discrete in tight winding packs. It is vital to use an insulating layer that is thin, fulfils the dielectric requirements, and can survive the heat treatment whose maximum temperature reaches 890 °C in oxygen. A thin (20-30 µm) ceramic coating could be better as the insulating layer compared to alumino-silicate braided fiber insulation, which is about 150 μm thick and reacts with the Ag sheathed Bi-2212 wire during heat treatment. At present, TiO2 seems to be the most viable ceramic material for such a thin insulation because it is chemically compatible with Ag and Bi-2212 and its sintering temperature is lower than the maximum temperature used for the Bi-2212 heat treatment. However, recent tests of a large Bi-2212 coil insulated only with TiO2 showed severe electrical shorting between the wires after over pressure heat treatment (OPHT). The origin of the shorting was frequent silver protrusions into the porous TiO2 layer that electrically connected adjacent Bi-2212 wires. To understand the mechanism of this unexpected behaviour, we investigated the effect of sheath material and hydrostatic pressure on Ag protrusions. We found that Ag protrusions occur only when TiO2-insulated Ag-0.2%Mg sheathed wire (Ag(Mg) wire) undergoes OPHT at 50 bar. No Ag protrusions were observed when the TiO2-insulated Ag(Mg) wire was processed at 1 bar. The TiO2-insulated wires sheathed with pure Ag that underwent 50 bar OPHT were also free from Ag protrusions. A key finding is that the Ag protrusions from the Ag(Mg) sheath actually contain no MgO, suggesting that local depletion of MgO facilitates local, heterogeneous deformation of the sheath under hydrostatic overpressure. Our study also suggests that predensifying the Ag(Mg) wire before insulating it with TiO2 and doing the final OPHT can potentially limit Ag protrusions.

Development of ultrasonic electrostatic microjets for distributed propulsion and microflight

NASA Astrophysics Data System (ADS)

Amirparviz, Babak

This dissertation details the first attempt to design and fabricate a distributed micro propulsion system based on acoustic streaming. A novel micro propulsion method is suggested by combining Helmholtz resonance, acoustic streaming and flow entrainment and thrust augmentation. In this method, oscillatory motion of an electrostatically actuated diaphragm creates a high frequency acoustic field inside the cavity of a Helmholtz resonator. The initial fluid motion velocity is amplified by the Helmholtz resonator structure and creates a jet flow at the exit nozzle. Acoustic streaming is the phenomenon responsible for primary jet stream creation. Primary jets produced by a few resonators can be combined in an ejector configuration to induce flow entrainment and thrust augmentation. Basic governing equations for the electrostatic actuator, deformation of the diaphragm and the fluid flow inside the resonator are derived. These equations are linearized and used to derive an equivalent electrical circuit model for the operation of the device. Numerical solution of the governing equations and simulation of the circuit model are used to predict the performance of the experimental systems. Thrust values as high as 30.3muN are expected per resonator. A micro machined electrostatically-driven high frequency Helmholtz resonator prototype is designed and fabricated. A new micro fabrication technique is developed for bulk micromachining and in particular fabrication of the resonator. Geometric stops for wet anisotropic etching of silicon are introduced for the fist time for structure formation. Arrays of high frequency (>60kHz) micro Helmholtz resonators are fabricated. In one sample more than 1000 resonators cover the surface of a four-inch silicon wafer and in effect convert it to a distributed propulsion system. A high yield (>85%) micro fabrication process is presented for realization of this propulsion system taking advantage of newly developed deep glass micromachining and lithography on thin (15mum) silicon methods. Extensive test and characterization are performed on the micro jets using current frequency component analysis, laser interferometry, acoustic measurements, hot-wire anemometers, video particle imaging and load cells. The occurrence of acoustic streaming at jet nozzles is verified and flow velocities exceeding 1m/s are measured at the 15mum x 330mum jet exit nozzle.

Effects of an Inhomogenous Electric Field on an Evaporating Thin Film in a Microchannel

NASA Astrophysics Data System (ADS)

Liu, Xiuliang; Hu, Chen; Li, Huafeng; Yu, Fei; Kong, Xiaming

2018-03-01

In this paper, heat transfer enhancement in an evaporating thin film along the wall of a microchannel under an imposed inhomogenous electrostatic field is analyzed. The mathematical model, based on the augmented Young-Laplace equation with the inhomogenous electrostatic field taken into consideration, is developed. The 2D inhomogenous electric field with the curved liquid-vapor interface is solved by the lattice Boltzmann method. Numerical solutions for the thin film characteristics are obtained for both constant wall temperature and uniform wall heat flux boundary conditions. The numerical results show that the liquid film becomes thinner and the heat transfer coefficient increases under an imposed electric field. Both of octane and water are chosen as the working mediums, and similar result about the enhancement of heat transfer on evaporating thin film by imposing electric field is obtained. It is found that applying an electric field on the evaporating thin film can enhance evaporative heat transfer in a microchannel.

Depositing High-T(sub c) Superconductors On Normal-Conductor Wires

NASA Technical Reports Server (NTRS)

Kirlin, Peter S.

1994-01-01

Experiments have demonstrated feasibility of depositing thin layers of high-T(sub c) superconductor on normally electrically conductive wires. Superconductivity evident at and below critical temperature (T{sub c}) of 71 K. OMCVD, organometallic vapor deposition, apparatus coats Ag wire with layer high-T(sub c) superconductor. Superconductive phase of this material formed subsequently by annealing under controlled conditions.

Solar Power Wires Based on Organic Photovoltaic Materials

NASA Astrophysics Data System (ADS)

Lee, Michael R.; Eckert, Robert D.; Forberich, Karen; Dennler, Gilles; Brabec, Christoph J.; Gaudiana, Russell A.

2009-04-01

Organic photovoltaics in a flexible wire format has potential advantages that are described in this paper. A wire format requires long-distance transport of current that can be achieved only with conventional metals, thus eliminating the use of transparent oxide semiconductors. A phase-separated, photovoltaic layer, comprising a conducting polymer and a fullerene derivative, is coated onto a thin metal wire. A second wire, coated with a silver film, serving as the counter electrode, is wrapped around the first wire. Both wires are encased in a transparent polymer cladding. Incident light is focused by the cladding onto to the photovoltaic layer even when it is completely shadowed by the counter electrode. Efficiency values of the wires range from 2.79% to 3.27%.

Flexible Microstrip Circuits for Superconducting Electronics

NASA Technical Reports Server (NTRS)

Chervenak, James; Mateo, Jennette

2013-01-01

Flexible circuits with superconducting wiring atop polyimide thin films are being studied to connect large numbers of wires between stages in cryogenic apparatus with low heat load. The feasibility of a full microstrip process, consisting of two layers of superconducting material separated by a thin dielectric layer on 5 mil (approximately 0.13 mm) Kapton sheets, where manageable residual stress remains in the polyimide film after processing, has been demonstrated. The goal is a 2-mil (approximately 0.051-mm) process using spin-on polyimide to take advantage of the smoother polyimide surface for achieving highquality metal films. Integration of microstrip wiring with this polyimide film may require high-temperature bakes to relax the stress in the polyimide film between metallization steps.

Characteristics of coated copper wire specimens using high frequency ultrasonic complex vibration welding equipments.

PubMed

Tsujino, J; Ihara, S; Harada, Y; Kasahara, K; Sakamaki, N

2004-04-01

Welding characteristic of thin coated copper wires were studied using 40, 60, 100 kHz ultrasonic complex vibration welding equipments with elliptical to circular vibration locus. The complex vibration systems consisted of a longitudinal-torsional vibration converter and a driving longitudinal vibration system. Polyurethane coated copper wires of 0.036 mm outer diameter and copper plates of 0.3 mm thickness and the other dimension wires were used as welding specimens. The copper wire part is completely welded on the copper substrate and the insulated coating material is driven from welded area to outsides of the wire specimens by high frequency complex vibration.

Numerical Analysis of Transient Temperature Response of Soap Film

NASA Astrophysics Data System (ADS)

Tanaka, Seiichi; Tatesaku, Akihiro; Dantsuka, Yuki; Fujiwara, Seiji; Kunimine, Kanji

2015-11-01

Measurements of thermophysical properties of thin liquid films are important to understand interfacial phenomena due to film structures composed of amphiphilic molecules in soap film, phospholipid bilayer of biological cell and emulsion. A transient hot-wire technique for liquid films less than 1 \\upmu m thick such as soap film has been proposed to measure the thermal conductivity and diffusivity simultaneously. Two-dimensional heat conduction equations for a solid cylinder with a liquid film have been solved numerically. The temperature of a thin wire with liquid film increases steeply with its own heat generation. The feasibility of this technique is verified through numerical experiments for various thermal conductivities, diffusivities, and film thicknesses. Calculated results indicate that the increase in the volumetric average temperature of the thin wire sufficiently varies with the change of thermal conductivity and diffusivity of the soap film. Therefore, the temperature characteristics could be utilized to evaluate both the thermal conductivity and diffusivity using the Gauss-Newton method.

Morphing hybrid honeycomb (MOHYCOMB) with in situ Poisson’s ratio modulation

NASA Astrophysics Data System (ADS)

Heath, Callum J. C.; Neville, Robin M.; Scarpa, Fabrizio; Bond, Ian P.; Potter, Kevin D.

2016-08-01

Electrostatic adhesion can be used as a means of reversible attachment. Through application of high voltage (~2 kV) across closely spaced parallel plate electrodes, significant shear stresses (11 kPa) can be generated. The highest levels of electrostatic holding force can be achieved through close contact of connection surfaces; this is facilitated by flexible electrodes which can conform to reduce air gaps. Cellular structures are comprised of thin walled elements, making them ideal host structures for electrostatic adhesive elements. The reversible adhesion provides control of the internal connectivity of the cellular structure, and determines the effective cell geometry. This would offer variable stiffness and control of the effective Poisson’s ratio of the global cellular array. Using copper-polyimide thin film laminates and PVDF thin film dielectrics, double lap shear electrostatic adhesive elements have been introduced to a cellular geometry. By activating different groups of reversible adhesive interfaces, the cellular array can assume four different cell configurations. A maximum stiffness modulation of 450% between the ‘All off’ and ‘All on’ cell morphologies has been demonstrated. This structure is also capable of in situ effective Poisson’s ratio variations, with the ability to switch between values of -0.45 and 0.54. Such a structure offers the potential for tuneable vibration absorption (due to its variable stiffness properties), or as a smart honeycomb with controllable curvature and is termed morphing hybrid honeycomb.

SMA Foils for MEMS: From Material Properties to the Engineering of Microdevices

NASA Astrophysics Data System (ADS)

Kohl, Manfred; Ossmer, Hinnerk; Gueltig, Marcel; Megnin, Christof

2018-03-01

In the early nineties, microelectromechanical systems (MEMS) technology has been still in its infancy. As silicon (Si) is not a transducer material, it was clear at the very beginning that mechanically active materials had to be introduced to MEMS in order to enable functional microdevices with actuation capability beyond electrostatics. At that time, shape memory alloys (SMAs) have been available in bulk form, mainly as SMA wires and SMA plates. On the macro scale, these materials show highest work densities compared to other actuation principles in the order of 107 J/m3, which stimulated research on the integration of SMA to MEMS. Subsequently, two approaches for producing planar materials have been initiated (1) magnetron sputtering of SMA thin films and (2) the integration of rolled SMA foils, which both turned out to be very successful creating a paradigm change in microactuation technology. The following review covers important milestones of the research and development of SMA foil-based microactuators including materials characterization, design engineering, technology, and demonstrator development as well as first commercial products.

SMA Foils for MEMS: From Material Properties to the Engineering of Microdevices

NASA Astrophysics Data System (ADS)

Kohl, Manfred; Ossmer, Hinnerk; Gueltig, Marcel; Megnin, Christof

2017-12-01

In the early nineties, microelectromechanical systems (MEMS) technology has been still in its infancy. As silicon (Si) is not a transducer material, it was clear at the very beginning that mechanically active materials had to be introduced to MEMS in order to enable functional microdevices with actuation capability beyond electrostatics. At that time, shape memory alloys (SMAs) have been available in bulk form, mainly as SMA wires and SMA plates. On the macro scale, these materials show highest work densities compared to other actuation principles in the order of 107 J/m3, which stimulated research on the integration of SMA to MEMS. Subsequently, two approaches for producing planar materials have been initiated (1) magnetron sputtering of SMA thin films and (2) the integration of rolled SMA foils, which both turned out to be very successful creating a paradigm change in microactuation technology. The following review covers important milestones of the research and development of SMA foil-based microactuators including materials characterization, design engineering, technology, and demonstrator development as well as first commercial products.

Applications of Thin Film Thermocouples for Surface Temperature Measurement

NASA Technical Reports Server (NTRS)

Martin, Lisa C.; Holanda, Raymond

1994-01-01

Thin film thermocouples provide a minimally intrusive means of measuring surface temperature in hostile, high temperature environments. Unlike wire thermocouples, thin films do not necessitate any machining of the surface, therefore leaving intact its structural integrity. Thin films are many orders of magnitude thinner than wire, resulting in less disruption to the gas flow and thermal patterns that exist in the operating environment. Thin film thermocouples have been developed for surface temperature measurement on a variety of engine materials. The sensors are fabricated in the NASA Lewis Research Center's Thin Film Sensor Lab, which is a class 1000 clean room. The thermocouples are platinum-13 percent rhodium versus platinum and are fabricated by the sputtering process. Thin film-to-leadwire connections are made using the parallel-gap welding process. Thermocouples have been developed for use on superalloys, ceramics and ceramic composites, and intermetallics. Some applications of thin film thermocouples are: temperature measurement of space shuttle main engine turbine blade materials, temperature measurement in gas turbine engine testing of advanced materials, and temperature and heat flux measurements in a diesel engine. Fabrication of thin film thermocouples is described. Sensor durability, drift rate, and maximum temperature capabilities are addressed.

Wrinkle-Free Hydroforming of Wire Mesh

NASA Technical Reports Server (NTRS)

Fadness, J.

1986-01-01

Plastic films lubricate workpiece so it deforms smoothly. Thin layers of plastic below top die and above bottom die ensure wire screen slides as shaped by hydroforming. Plastic layers are 0.0043 in. (0.11 m) thick. Preformed to contours of dies and final workpiece. New method of hydroforming fine-wire-mesh heat-shield screens eliminates wrinkles and marks. Prevents screen from being damaged and pores from becoming blocked.

Electronic scraps--recovering of valuable materials from parallel wire cables.

PubMed

de Araújo, Mishene Christie Pinheiro Bezerra; Chaves, Arthur Pinto; Espinosa, Denise Crocce Romano; Tenório, Jorge Alberto Soares

2008-11-01

Every year, the number of discarded electro-electronic products is increasing. For this reason recycling is needed, to avoid wasting non-renewable natural resources. The objective of this work is to study the recycling of materials from parallel wire cable through unit operations of mineral processing. Parallel wire cables are basically composed of polymer and copper. The following unit operations were tested: grinding, size classification, dense medium separation, electrostatic separation, scrubbing, panning, and elutriation. It was observed that the operations used obtained copper and PVC concentrates with a low degree of cross contamination. It was concluded that total liberation of the materials was accomplished after grinding to less than 3 mm, using a cage mill. Separation using panning and elutriation presented the best results in terms of recovery and cross contamination.

Role of out-of-plane dielectric thickness in the electrostatic simulation of atomically thin lateral junctions

NASA Astrophysics Data System (ADS)

Nipane, Ankur; Zhang, Yefei; Teherani, James T.

2018-06-01

Two-dimensional materials enable novel electronic and optoelectronic devices due to their unique properties. Device modeling plays a fundamental role in developing these novel devices by providing insights into the underlying physics. In this work, we present the dramatic impact of the simulated out-of-plane dielectric thickness on the electrostatics of lateral junctions formed from atomically thin materials. We show that unlike bulk junctions, the boundary conditions on the edges of the simulation region significantly affect the electrostatics of two-dimensional (2D) lateral junctions by modifying the out-of-plane electric field. We also present an intuitive understanding of the Neumann boundary conditions imposed on the boundaries of the simulation region. The Neumann boundary conditions alter the intended simulation by generating reflections of the device across the boundaries. Finally, we derive a minimal dielectric thickness for a symmetrically doped 2D lateral p-n junction, above which the out-of-plane simulation region boundaries minimally affect the simulated electric field, electrostatic potential, and depletion width of the junction.

Onset of two-dimensional superconductivity in space charge doped few-layer molybdenum disulfide

NASA Astrophysics Data System (ADS)

Biscaras, Johan; Chen, Zhesheng; Paradisi, Andrea; Shukla, Abhay

2015-11-01

Atomically thin films of layered materials such as molybdenum disulfide (MoS2) are of growing interest for the study of phase transitions in two-dimensions through electrostatic doping. Electrostatic doping techniques giving access to high carrier densities are needed to achieve such phase transitions. Here we develop a method of electrostatic doping which allows us to reach a maximum n-doping density of 4 × 1014 cm-2 in few-layer MoS2 on glass substrates. With increasing carrier density we first induce an insulator to metal transition and subsequently an incomplete metal to superconductor transition in MoS2 with critical temperature ~10 K. Contrary to earlier reports, after the onset of superconductivity, the superconducting transition temperature does not depend on the carrier density. Our doping method and the results we obtain in MoS2 for samples as thin as bilayers indicates the potential of this approach.

An Electrostatically Self-Assembled Thin Film Made of Zn-Substituted Tungstoborate and Rhodamine B with Photoelectrochemical Properties.

PubMed

Mao, Xu; Zhang, Jia-Ning; Gao, Li-Hua; Su, Yu; Chen, Peng-Xia; Wang, Ke-Zhi

2016-04-01

An electrostatically self-assembled multilayer thin film consisting of alternating layers of Keggin polyoxometalate of Zn-substituted tungstoborate (BW11Zn) and Rhodamine B (RhB) has successfully been prepared on a quartz and indium-tin oxide (ITO) glass substrate. The ultraviolet-visible (UV-vis) absorption spectra demonstrated that the electrostatically self-assembled film of (BW11Zn/RhB)n was uniformly deposited layer by layer, and the RhB molecules in the film formed the J-aggregation. The photoelectrochemical investigations showed that the films generated stable cathodic photocurrents that originated from RhB, and the maximal cathodic photocurrent density generated by an eight-layer film was 4.9 µA/cm2 while the film was irradiated with 100 mW/cm2 polychromatic light of 730 nm > λ > 325 nm at an applied potential of 0 V versus a saturated calomel electrode.

MEMS deformable mirror embedded wavefront sensing and control system

NASA Astrophysics Data System (ADS)

Owens, Donald; Schoen, Michael; Bush, Keith

2006-01-01

Electrostatic Membrane Deformable Mirror (MDM) technology developed using silicon bulk micro-machining techniques offers the potential of providing low-cost, compact wavefront control systems for diverse optical system applications. Electrostatic mirror construction using bulk micro-machining allows for custom designs to satisfy wavefront control requirements for most optical systems. An electrostatic MDM consists of a thin membrane, generally with a thin metal or multi-layer high-reflectivity coating, suspended over an actuator pad array that is connected to a high-voltage driver. Voltages applied to the array elements deflect the membrane to provide an optical surface capable of correcting for measured optical aberrations in a given system. Electrostatic membrane DM designs are derived from well-known principles of membrane mechanics and electrostatics, the desired optical wavefront control requirements, and the current limitations of mirror fabrication and actuator drive electronics. MDM performance is strongly dependent on mirror diameter and air damping in meeting desired spatial and temporal frequency requirements. In this paper, we present wavefront control results from an embedded wavefront control system developed around a commercially available high-speed camera and an AgilOptics Unifi MDM driver using USB 2.0 communications and the Linux development environment. This new product, ClariFast TM, combines our previous Clarifi TM product offering into a faster more streamlined version dedicated strictly to Hartmann Wavefront sensing.

A user's manual for the Electromagnetic Surface Patch code: ESP version 3

NASA Technical Reports Server (NTRS)

Newman, E. H.; Dilsavor, R. L.

1987-01-01

This report serves as a user's manual for Version III of the Electromagnetic Surface Patch Code or ESP code. ESP is user-oriented, based on the method of moments (MM) for treating geometries consisting of an interconnection of thin wires and perfectly conducting polygonal plates. Wire/plate junctions must be about 0.1 lambda or more from any plate edge. Several plates may intersect along a common edge. Excitation may be by either a delta-gap voltage generator or by a plane wave. The thin wires may have finite conductivity and also may contain lumped loads. The code computes most of the usual quantities of interest such as current distribution, input impedance, radiation efficiency, mutual coupling, far zone gain patterns (both polarizations) and radar-cross-section (both/cross polarizations).

Microspectroscopy with Terahertz bioMEMS

NASA Astrophysics Data System (ADS)

Akalin, Tahsin; Treizebré, Anthony

2006-04-01

Biological applications require more and more compact, sensitive and reliable microsystems. We will present solutions in order to realize a "microspectroscopy" up to Terahertz frequencies of various biological entities (living cell, neurons, proteins...). We investigate these entities in liquid phase. In a recent work, we have demonstrated a solution to excite efficiently a single wire transmission line [1]. The propagation mode is similar to a surface plasmon and known as a Goubau-mode [2]. The wire we used is extremely thin compared to other recent solutions at terahertz frequencies. There are three orders of magnitude in the size of the wire used by K. Wang and D.M. Mittleman. Typically the wire's width is 1μm compared to the 900μm diameter metal wire in [3]. Moreover our solution is in a planar configuration which is more suitable for microfluidic applications. We benefit from the high confinement of the electromagnetic field around this very thin gold wire to optimize the sensitivity of these Terahertz BioMEMS. Microfluidic channels are placed below the strip in a perpendicular direction. We will first present some properties of the Planar Goubau-Line (PGL) [4] and the measurements results obtained with structures fabricated on glass and quartz substrates. In a last part resonant structures and Mach-Zehnder type interferometers will also be presented.

Highly Conductive Thin Uniform Gold-Coated DNA Nanowires.

PubMed

Stern, Avigail; Eidelshtein, Gennady; Zhuravel, Roman; Livshits, Gideon I; Rotem, Dvir; Kotlyar, Alexander; Porath, Danny

2018-06-01

Over the past decades, DNA, the carrier of genetic information, has been used by researchers as a structural template material. Watson-Crick base pairing enables the formation of complex 2D and 3D structures from DNA through self-assembly. Various methods have been developed to functionalize these structures for numerous utilities. Metallization of DNA has attracted much attention as a means of forming conductive nanostructures. Nevertheless, most of the metallized DNA wires reported so far suffer from irregularity and lack of end-to-end electrical connectivity. An effective technique for formation of thin gold-coated DNA wires that overcomes these drawbacks is developed and presented here. A conductive atomic force microscopy setup, which is suitable for measuring tens to thousands of nanometer long molecules and wires, is used to characterize these DNA-based nanowires. The wires reported here are the narrowest gold-coated DNA wires that display long-range conductivity. The measurements presented show that the conductivity is limited by defects, and that thicker gold coating reduces the number of defects and increases the conductive length. This preparation method enables the formation of molecular wires with dimensions and uniformity that are much more suitable for DNA-based molecular electronics. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Using the Cycloid as an Introduction to Transformations of "E" and "B" Fields

ERIC Educational Resources Information Center

Frodyma, Marc; Le, My Phuong

2018-01-01

The transformations of electric and magnetic fields are usually introduced by viewing systems such as a long, straight current-carrying wire and a parallel plate capacitor in two different reference frames. These well-known examples show that magnetism is a necessary consequence of augmenting electrostatics with relativity. Because they require…

Magnetic properties of permalloy wires in vycor capillaries

NASA Astrophysics Data System (ADS)

Lubitz, P.; Ayers, J. D.; Davis, A.

1991-11-01

Thin wires of NiFe alloys with compositions near 80% Ni were prepared by melting the alloy in vycor tubes and drawing fibers from the softened glass. The resulting fibers consist of relatively thick-walled vycor capillaries containing permalloy wires filling a few percent of the volume. The wires are continuous over considerable lengths, uniform in circular cross section, nearly free of contact with the walls and can be drawn to have diameters less than 1 μm. Their magnetic properties are generally similar to bulk permalloy, but show a variety of magnetic switching behaviors for fields along the wire axis, depending on composition, wire diameter, and thermal history. As pulled, the wires can show sharp switching, reversible rotation or mixed behavior. This method can produce NiFe alloy wires suitable for use in applications as sensor, memory or inductive elements; other alloys, such as supermalloy and sendust, also can be fabricated as fine wires by this method.

Electrostatic Deformation of Liquid Surfaces by a Charged Rod and a Van De Graaff Generator

ERIC Educational Resources Information Center

Slisko, Josip; García-Molina, Rafael; Abril, Isabel

2014-01-01

Authors of physics textbooks frequently use the deflection of a thin, vertically falling water jet by a charged balloon, comb, or rod as a visually appealing and conceptually relevant example of electrostatic attraction. Nevertheless, no attempts are made to explore whether these charged bodies could cause visible deformation of a horizontal water…

On the influence that the ground electrode diameter has in the propulsion efficiency of an asymmetric capacitor in nitrogen gas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martins, Alexandre A.; Pinheiro, Mario J.

In this work, the propulsion force developed in an asymmetric capacitor will be calculated for three different diameters of the ground electrode. The used ion source is a small diameter wire, which generates a positive corona discharge in nitrogen gas directed to the ground electrode. By applying the fluid dynamic and electrostatic theories, all hydrodynamic and electrostatic forces that act on the considered geometries will be computed in an attempt to provide a physical insight on the force mechanism that acts on the asymmetrical capacitors, and also to understand how to increase the efficiency of propulsion.

Deposition of thermal and hot-wire chemical vapor deposition copper thin films on patterned substrates.

PubMed

Papadimitropoulos, G; Davazoglou, D

2011-09-01

In this work we study the hot-wire chemical vapor deposition (HWCVD) of copper films on blanket and patterned substrates at high filament temperatures. A vertical chemical vapor deposition reactor was used in which the chemical reactions were assisted by a tungsten filament heated at 650 degrees C. Hexafluoroacetylacetonate Cu(I) trimethylvinylsilane (CupraSelect) vapors were used, directly injected into the reactor with the aid of a liquid injection system using N2 as carrier gas. Copper thin films grown also by thermal and hot-wire CVD. The substrates used were oxidized silicon wafers on which trenches with dimensions of the order of 500 nm were formed and subsequently covered with LPCVD W. HWCVD copper thin films grown at filament temperature of 650 degrees C showed higher growth rates compared to the thermally ones. They also exhibited higher resistivities than thermal and HWCVD films grown at lower filament temperatures. Thermally grown Cu films have very uniform deposition leading to full coverage of the patterned substrates while the HWCVD films exhibited a tendency to vertical growth, thereby creating gaps and incomplete step coverage.

Wire Frame Holds Water-Soap Film in Space

NASA Technical Reports Server (NTRS)

2003-01-01

Expedition 6 astronaut Dr. Don Pettit photographed a cube shaped wire frame supporting a thin film made from a water-soap solution during his Saturday Morning Science aboard the International Space Station's (ISS) Destiny Laboratory. Food coloring was added to several faces to observe the effects of diffusion within the film.

Fragmentation of Thin Wires under High Voltage Pulses and Bipolar Fusion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Papageorgiou, C. D.; Raptis, T. E.

2010-01-21

In this article we present an alternative explanation of the phenomenon of wire fragmentation under high transient currents based on classical electromagnetism. We also explain how this phenomenon can be utilized as a primitive example of low energy-high power disruptive phenomena that can affect even nuclear matter.

An investigation of flow-limited field-injection electrostatic spraying (FFESS) and its applications to thin film deposition

NASA Astrophysics Data System (ADS)

Singh, Ravindra Pratap

Electrostatic spraying is the process of controlled disruption of a liquid surface due to excess surface charge density. The technique has found applications in a wide range of fields from agricultural sprays to fuel injectors to colloidal thrusters for space vehicle propulsion. Over the past 20 years, the technique has been intensely studied in material processing for synthesis of ceramic and metal powders, nanoparticles and thin films. The importance of the technique lies in its simple setup, high deposition efficiency, and ambient atmosphere operation. In conventional electrostatic spraying (CESS), one uses a conducting nozzle to charge the liquid, mostly by induction charging. CESS is therefore restricted to the single jet mode of spraying which occurs at low spray currents. It lacks stability and reproducibility in the high current, multiple jet regime, which can generate much finer sprays. In flow-limited field-injection electrostatic spraying (FFESS), one uses a field-injection electrode to stably and controllably inject higher currents into the liquid, a la Fowler-Nordheim, using an otherwise insulating nozzle. This way, it is possible to stably electrospray in the multiple jet mode. In addition to producing much finer sprays, the multi-jet mode atomizes liquids at higher rates, and spreads the spray over a wider region and more uniformly than single jet sprays, thus paving way for large-area uniform thin film deposition. A simple yet comprehensive theory is formulated to describe the multi jet formation. The theory, which is based on the energy minimization principle, takes into account, for the first time, the interactions between charged jets which leads to saturation in the number of jets at high spray currents. The possibility of using an array of nozzles to obtain uniform large-area high-throughput thin film deposition is also investigated. A large number of FFESS nozzles with alternating positive and negative polarities arranged in a periodic 2-dimensional array are found to produce uniform thin films over large areas. Deposition of TiO2 and silver thin films using multi jet FFESS is studied, demonstrating great control on film morphology and properties. TiO2 thin films deposited on high-intensity discharge arc lamps are found to improve the quality of its light output. Silver thin films of high purity and conductivity, and with good adhesion, could be deposited at relatively high deposition rates and high deposition efficiency as compared to CVD techniques.

Metallurgical investigation of wire breakage of tyre bead grade.

PubMed

Palit, Piyas; Das, Souvik; Mathur, Jitendra

2015-10-01

Tyre bead grade wire is used for tyre making application. The wire is used as reinforcement inside the polymer of tyre. The wire is available in different size/section such as 1.6-0.80 mm thin Cu coated wire. During tyre making operation at tyre manufacturer company, wire failed frequently. In this present study, different broken/defective wire samples were collected from wire mill for detailed investigation of the defect. The natures of the defects were localized and similar in nature. The fracture surface was of finger nail type. Crow feet like defects including button like surface abnormalities were also observed on the broken wire samples. The defect was studied at different directions under microscope. Different advanced metallographic techniques have been used for detail investigation. The analysis revealed that, white layer of surface martensite was formed and it caused the final breakage of wire. In this present study we have also discussed about the possible reason for the formation of such kind of surface martensite (hard-phase).

The Insulation of Copper Wire by the Electrostatic Coating Process.

DTIC Science & Technology

1983-06-30

fluorinated ethylene propylene), ECFTE (ethylene- chlorotrifluoro ethylene), and PFA (perfluoroalkoxy resin). Another material of interest with good...Fluoroplastics - Fluoroplastics are a family of polymers with the general paraffin structure that have some or all of the hydrogen replaced by fluorine ...ETFE (ethylene-tetrafluoroethylene copolymer), PFA (perfluoroalkoxy resin), ECTFE (ethylene-chlorotrifluoroethylene), and FEP ( fluorinated ethylene

An Electrostatic-Barrier-Forming Window that Captures Airborne Pollen Grains to Prevent Pollinosis

PubMed Central

Takikawa, Yoshihiro; Matsuda, Yoshinori; Nonomura, Teruo; Kakutani, Koji; Kusakari, Shin-Ichi; Toyoda, Hideyoshi

2017-01-01

An electrostatic-barrier-forming window (EBW) was devised to capture airborne pollen, which can cause allergic pollinosis. The EBW consisted of three layers of insulated conductor wires (ICWs) and two voltage generators that supplied negative charges to the two outer ICW layers and a positive charge to the middle ICW layer. The ICWs generated an attractive force that captured pollen of the Japanese cedar, Cryptomeria japonica, from air blown through the EBW. The attractive force was directly proportional to the applied voltage. At ≥3.5 kV, the EBW exerted sufficient force to capture all pollen carried at an air flow of 3 m/s, and pollen-free air passed through the EBW. The findings demonstrated that the electrostatic barrier that formed inside the EBW was very effective at capturing airborne pollen; thus, it could allow a home to remain pollen-free and healthy despite continuous pollen exposure. PMID:28098835

An Electrostatic-Barrier-Forming Window that Captures Airborne Pollen Grains to Prevent Pollinosis.

PubMed

Takikawa, Yoshihiro; Matsuda, Yoshinori; Nonomura, Teruo; Kakutani, Koji; Kusakari, Shin-Ichi; Toyoda, Hideyoshi

2017-01-15

An electrostatic-barrier-forming window (EBW) was devised to capture airborne pollen, which can cause allergic pollinosis. The EBW consisted of three layers of insulated conductor wires (ICWs) and two voltage generators that supplied negative charges to the two outer ICW layers and a positive charge to the middle ICW layer. The ICWs generated an attractive force that captured pollen of the Japanese cedar, Cryptomeria japonica , from air blown through the EBW. The attractive force was directly proportional to the applied voltage. At ≥3.5 kV, the EBW exerted sufficient force to capture all pollen carried at an air flow of 3 m/s, and pollen-free air passed through the EBW. The findings demonstrated that the electrostatic barrier that formed inside the EBW was very effective at capturing airborne pollen; thus, it could allow a home to remain pollen-free and healthy despite continuous pollen exposure.

Electrostatic micromotor based on ferroelectric ceramics

NASA Astrophysics Data System (ADS)

Baginsky, I. L.; Kostsov, E. G.

2004-11-01

A new electrostatic micromotor is described that utilizes the electromechanical energy conversion principle earlier described by the authors. The electromechanical energy conversion is based on reversible electrostatic rolling of thin metallic films (petals) on a ferroelectric surface. The motor's active media are layers of ferroelectric ceramics (about 100 µm in thickness). The characteristics of the electrostatic rolling of the petals on different ceramic surfaces are studied, as well as the dynamic characteristics of the micromotors. It is shown that the use of antiferroelectric material allows one to reach a specific energy capacitance comparable to that of the micromotors based on ferroelectric films and to achieve a specific power of 30-300 µW mm-2.

Development of Thin Film Thermocouples on Ceramic Materials for Advanced Propulsion System Applications

NASA Technical Reports Server (NTRS)

Holanda, R.

1992-01-01

Thin film thermocouples have been developed for use on metal parts in jet engines to 1000 c. However, advanced propulsion systems are being developed that will use ceramic materials and reach higher temperatures. The purpose of this work is to develop thin film thermocouples for use on ceramic materials. The new thin film thermocouples are Pt13Rh/Pt fabricated by the sputtering process. Lead wires are attached using the parallel-gap welding process. The ceramic materials tested are silicon nitride, silicon carbide, aluminum oxide, and mullite. Both steady state and thermal cycling furnace tests were performed in the temperature range to 1500 C. High-heating-rate tests were performed in an arc lamp heat-flux-calibration facility. The fabrication of the thin film thermocouples is described. The thin film thermocouple output was compared to a reference wire thermocouple. Drift of the thin film thermocouples was determined, and causes of drift are discussed. The results of high heating rate tests up to 2500 C/sec are presented. The stability of the ceramic materials is examined. It is concluded that Pt13Rh/Pt thin film thermocouples are capable of meeting lifetime goals of 50 hours or more up to temperature of 1500 C depending on the stability of the particular ceramic substrate.

Thin film thermocouples for high temperature measurement on ceramic materials

NASA Technical Reports Server (NTRS)

Holanda, Raymond

1992-01-01

Thin film thermocouples have been developed for use on metal parts in jet engines to 1000 C. However, advanced propulsion systems are being developed that will use ceramic materials and reach higher temperatures. The purpose of this work is to develop thin film thermocouples for use on ceramic materials. The thin film thermocouples are Pt13Rh/Pt fabricated by the sputtering process. Lead wires are attached using the parallel-gap welding process. The ceramic materials are silicon nitride, silicon carbide, aluminum oxide, and mullite. Both steady state and thermal cycling furnace tests were performed in the temperature range to 1500 C. High-heating-rate tests were performed in an arc lamp heat-flux-calibration facility. The fabrication of the thin film thermocouples is described. The thin film thermocouple output was compared to a reference wire thermocouple. Drift of the thin film thermocouples was determined, and causes of drift are discussed. The results of high-heating-rate tests up to 2500 C/sec are presented. The stability of the ceramic materials is examined. It is concluded that Pt13Rh/Pt thin film thermocouples are capable of meeting lifetime goals of 50 hours or more up to temperatures of 1500 C depending on the stability of the particular ceramic substrate.

Development of thin film thermocouples on ceramic materials for advanced propulsion system applications

NASA Technical Reports Server (NTRS)

Holanda, Raymond

1993-01-01

Thin film thermocouples were developed for use on metal parts in jet engines to 1000 C. However, advanced propulsion systems are being developed that will use ceramic materials and reach higher temperatures. The purpose is to develop thin film thermocouples for use on ceramic materials. The new thin film thermocouples are Pt13Rh/Pt fabricated by the sputtering process. Lead wires are attached using the parallel-gap welding process. The ceramic materials tested are silicon nitride, silicon carbide, aluminum oxide, and mullite. Both steady state and thermal cycling furnace tests were performed in the temperature range to 1500 C. High-heating-rate tests were performed in an arc lamp heat-flux-calibration facility. The fabrication of the thin film thermocouples is described. The thin film thermocouple output was compared to a reference wire thermocouple. Drift of the thin film thermocouples was determined, and causes of drift are discussed. The results of high heating rate tests up to 2500 C/sec are presented. The stability of the ceramic materials is examined. It is concluded that Pt13Rh/Pt thin film thermocouples are capable of meeting lifetime goals of 50 hr or more up to temperatures of 1500 C depending on the stability of the particular ceramic substrate.

Aerogel-supported filament

DOEpatents

Wuest, Craig R.; Tillotson, Thomas M.; Johnson, III, Coleman V.

1995-01-01

The present invention is a thin filament embedded in a low density aerogel for use in radiation detection instruments and incandescent lamps. The aerogel provides a supportive matrix that is thermally and electrically nonconductive, mechanically strong, highly porous, gas-permeable, and transparent to ionizing radiation over short distances. A low density, open-cell aerogel is cast around a fine filament or wire, which allows the wire to be positioned with little or no tension and keeps the wire in place in the event of breakage. The aerogel support reduces the stresses on the wire caused by vibrational, gravitational, electrical, and mechanical forces.

Aerogel-supported filament

DOEpatents

Wuest, C.R.; Tillotson, T.M.; Johnson, C.V. III

1995-05-16

The present invention is a thin filament embedded in a low density aerogel for use in radiation detection instruments and incandescent lamps. The aerogel provides a supportive matrix that is thermally and electrically nonconductive, mechanically strong, highly porous, gas-permeable, and transparent to ionizing radiation over short distances. A low density, open-cell aerogel is cast around a fine filament or wire, which allows the wire to be positioned with little or no tension and keeps the wire in place in the event of breakage. The aerogel support reduces the stresses on the wire caused by vibrational, gravitational, electrical, and mechanical forces. 6 Figs.

Piezo-Potential Generation in Capacitive Flexible Sensors Based on GaN Horizontal Wires.

PubMed

El Kacimi, Amine; Pauliac-Vaujour, Emmanuelle; Delléa, Olivier; Eymery, Joël

2018-06-12

We report an example of the realization of a flexible capacitive piezoelectric sensor based on the assembly of horizontal c¯-polar long Gallium nitride (GaN) wires grown by metal organic vapour phase epitaxy (MOVPE) with the Boostream ® technique spreading wires on a moving liquid before their transfer on large areas. The measured signal (<0.6 V) obtained by a punctual compression/release of the device shows a large variability attributed to the dimensions of the wires and their in-plane orientations. The cause of this variability and the general operating mechanisms of this flexible capacitive device are explained by finite element modelling simulations. This method allows considering the full device composed of a metal/dielectric/wires/dielectric/metal stacking. We first clarify the mechanisms involved in the piezo-potential generation by mapping the charge and piezo-potential in a single wire and studying the time-dependent evolution of this phenomenon. GaN wires have equivalent dipoles that generate a tension between metallic electrodes only when they have a non-zero in-plane projection. This is obtained in practice by the conical shape occurring spontaneously during the MOVPE growth. The optimal aspect ratio in terms of length and conicity (for the usual MOVPE wire diameter) is determined for a bending mechanical loading. It is suggested to use 60⁻120 µm long wires (i.e., growth time less than 1 h). To study further the role of these dipoles, we consider model systems with in-plane 1D and 2D regular arrays of horizontal wires. It is shown that a strong electrostatic coupling and screening occur between neighbouring horizontal wires depending on polarity and shape. This effect, highlighted here only from calculations, should be taken into account to improve device performance.

Low cost, formable, high T(sub c) superconducting wire

NASA Technical Reports Server (NTRS)

Smialek, James L. (Inventor)

1991-01-01

A ceramic superconductivity part such as a wire is produced through the partial oxidation of a specially formulated copper alloy in the core. The alloys contain low level quantities of rare earth and alkaline earth dopant elements. Upon oxidation at high temperature, superconducting oxide phases are formed as a thin film.

Media-Rich Learning through Universal Computing and Wireless Thin Client.

ERIC Educational Resources Information Center

Cain, Mark

There is a whole infrastructure that must support a successful universal student computing requirement. Conventional approaches would have the students plugging into a wired network. That would necessitate network wires and hubs or many ports in each classroom. Students would need access to course-related software. Because the needs would change…

Breakdown dynamics of electrically exploding thin metal wires in vacuum

NASA Astrophysics Data System (ADS)

Sarkisov, G. S.; Caplinger, J.; Parada, F.; Sotnikov, V. I.

2016-10-01

Using a two-frame intensified charge coupled device (iCCD) imaging system with a 2 ns exposure time, we observed the dynamics of voltage breakdown and corona generation in experiments of fast ns-time exploding fine Ni and stainless-steel (SS) wires in a vacuum. These experiments show that corona generation along the wire surface is subjected to temporal-spatial inhomogeneity. For both metal wires, we observed an initial generation of a bright cathode spot before the ionization of the entire wire length. This cathode spot does not expand with time. For 25.4 μm diameter Ni and SS wire explosions with positive polarity, breakdown starts from the ground anode and propagates to the high voltage cathode with speeds approaching 3500 km/s or approximately one percent of light speed.

Self-healable electrically conducting wires for wearable microelectronics.

PubMed

Sun, Hao; You, Xiao; Jiang, Yishu; Guan, Guozhen; Fang, Xin; Deng, Jue; Chen, Peining; Luo, Yongfeng; Peng, Huisheng

2014-09-01

Electrically conducting wires play a critical role in the advancement of modern electronics and in particular are an important key to the development of next-generation wearable microelectronics. However, the thin conducting wires can easily break during use, and the whole device fails to function as a result. Herein, a new family of high-performance conducting wires that can self-heal after breaking has been developed by wrapping sheets of aligned carbon nanotubes around polymer fibers. The aligned carbon nanotubes offer an effective strategy for the self-healing of the electric conductivity, whereas the polymer fiber recovers its mechanical strength. A self-healable wire-shaped supercapacitor fabricated from a wire electrode of this type maintained a high capacitance after breaking and self-healing. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Finite element simulations of electrostatic dopant potentials in thin semiconductor specimens for electron holography.

PubMed

Somodi, P K; Twitchett-Harrison, A C; Midgley, P A; Kardynał, B E; Barnes, C H W; Dunin-Borkowski, R E

2013-11-01

Two-dimensional finite element simulations of electrostatic dopant potentials in parallel-sided semiconductor specimens that contain p-n junctions are used to assess the effect of the electrical state of the surface of a thin specimen on projected potentials measured using off-axis electron holography in the transmission electron microscope. For a specimen that is constrained to have an equipotential surface, the simulations show that the step in the projected potential across a p-n junction is always lower than would be predicted from the properties of the bulk device, but is relatively insensitive to the value of the surface state energy, especially for thicker specimens and higher dopant concentrations. The depletion width measured from the projected potential, however, has a complicated dependence on specimen thickness. The results of the simulations are of broader interest for understanding the influence of surfaces and interfaces on electrostatic potentials in nanoscale semiconductor devices. © 2013 Elsevier B.V. All rights reserved.

Amine-Rich Organic Thin Films for Cell Culture: Possible Electrostatic Effects in Cell-Surface Interactions

NASA Astrophysics Data System (ADS)

Wertheimer, Michael R.; St-Georges-Robillard, Amélie; Lerouge, Sophie; Mwale, Fackson; Elkin, Bentsian; Oehr, Christian; Wirges, Werner; Gerhard, Reimund

2012-11-01

In recent communications from these laboratories, we observed that amine-rich thin organic layers are very efficient surfaces for the adhesion of mammalian cells. We prepare such deposits by plasma polymerization at low pressure, atmospheric pressure, or by vacuum-ultraviolet photo-polymerization. More recently, we have also investigated a commercially available material, Parylene diX AM. In this article we first briefly introduce literature relating to electrostatic interactions between cells, proteins, and charged surfaces. We then present certain selected cell-response results that pertain to applications in orthopedic and cardiovascular medicine: we discuss the influence of surface properties on the observed behaviors of two particular cell lines, human U937 monocytes, and Chinese hamster ovary cells. Particular emphasis is placed on possible electrostatic attractive forces due to positively charged R-NH3+ groups and negatively charged proteins and cells, respectively. Experiments carried out with electrets, polymers with high positive or negative surface potentials are added for comparison.

Onset of two-dimensional superconductivity in space charge doped few-layer molybdenum disulfide

PubMed Central

Biscaras, Johan; Chen, Zhesheng; Paradisi, Andrea; Shukla, Abhay

2015-01-01

Atomically thin films of layered materials such as molybdenum disulfide (MoS2) are of growing interest for the study of phase transitions in two-dimensions through electrostatic doping. Electrostatic doping techniques giving access to high carrier densities are needed to achieve such phase transitions. Here we develop a method of electrostatic doping which allows us to reach a maximum n-doping density of 4 × 1014 cm−2 in few-layer MoS2 on glass substrates. With increasing carrier density we first induce an insulator to metal transition and subsequently an incomplete metal to superconductor transition in MoS2 with critical temperature ≈10 K. Contrary to earlier reports, after the onset of superconductivity, the superconducting transition temperature does not depend on the carrier density. Our doping method and the results we obtain in MoS2 for samples as thin as bilayers indicates the potential of this approach. PMID:26525386

Direct impact aerosol sampling by electrostatic precipitation

DOEpatents

Braden, Jason D.; Harter, Andrew G.; Stinson, Brad J.; Sullivan, Nicholas M.

2016-02-02

The present disclosure provides apparatuses for collecting aerosol samples by ionizing an air sample at different degrees. An air flow is generated through a cavity in which at least one corona wire is disposed and electrically charged to form a corona therearound. At least one grounded sample collection plate is provided downstream of the at least one corona wire so that aerosol ions generated within the corona are deposited on the at least one grounded sample collection plate. A plurality of aerosol samples ionized to different degrees can be generated. The at least one corona wire may be perpendicular to the direction of the flow, or may be parallel to the direction of the flow. The apparatus can include a serial connection of a plurality of stages such that each stage is capable of generating at least one aerosol sample, and the air flow passes through the plurality of stages serially.

Thermal conductance of Nb thin films at sub-kelvin temperatures.

PubMed

Feshchenko, A V; Saira, O-P; Peltonen, J T; Pekola, J P

2017-02-03

We determine the thermal conductance of thin niobium (Nb) wires on a silica substrate in the temperature range of 0.1-0.6 K using electron thermometry based on normal metal-insulator-superconductor tunnel junctions. We find that at 0.6 K, the thermal conductance of Nb is two orders of magnitude lower than that of Al in the superconducting state, and two orders of magnitude below the Wiedemann-Franz conductance calculated with the normal state resistance of the wire. The measured thermal conductance exceeds the prediction of the Bardeen-Cooper-Schrieffer theory, and demonstrates a power law dependence on temperature as T 4.5 , instead of an exponential one. At the same time, we monitor the temperature profile of the substrate along the Nb wire to observe possible overheating of the phonon bath. We show that Nb can be successfully used for thermal insulation in a nanoscale circuit while simultaneously providing an electrical connection.

Thermal conductance of Nb thin films at sub-kelvin temperatures

NASA Astrophysics Data System (ADS)

Feshchenko, A. V.; Saira, O.-P.; Peltonen, J. T.; Pekola, J. P.

2017-02-01

We determine the thermal conductance of thin niobium (Nb) wires on a silica substrate in the temperature range of 0.1-0.6 K using electron thermometry based on normal metal-insulator-superconductor tunnel junctions. We find that at 0.6 K, the thermal conductance of Nb is two orders of magnitude lower than that of Al in the superconducting state, and two orders of magnitude below the Wiedemann-Franz conductance calculated with the normal state resistance of the wire. The measured thermal conductance exceeds the prediction of the Bardeen-Cooper-Schrieffer theory, and demonstrates a power law dependence on temperature as T4.5, instead of an exponential one. At the same time, we monitor the temperature profile of the substrate along the Nb wire to observe possible overheating of the phonon bath. We show that Nb can be successfully used for thermal insulation in a nanoscale circuit while simultaneously providing an electrical connection.

Metallic and Ceramic Thin Film Thermocouples for Gas Turbine Engines

PubMed Central

Tougas, Ian M.; Amani, Matin; Gregory, Otto J.

2013-01-01

Temperatures of hot section components in today's gas turbine engines reach as high as 1,500 °C, making in situ monitoring of the severe temperature gradients within the engine rather difficult. Therefore, there is a need to develop instrumentation (i.e., thermocouples and strain gauges) for these turbine engines that can survive these harsh environments. Refractory metal and ceramic thin film thermocouples are well suited for this task since they have excellent chemical and electrical stability at high temperatures in oxidizing atmospheres, they are compatible with thermal barrier coatings commonly employed in today's engines, they have greater sensitivity than conventional wire thermocouples, and they are non-invasive to combustion aerodynamics in the engine. Thin film thermocouples based on platinum:palladium and indium oxynitride:indium tin oxynitride as well as their oxide counterparts have been developed for this purpose and have proven to be more stable than conventional type-S and type-K thin film thermocouples. The metallic and ceramic thin film thermocouples described within this paper exhibited remarkable stability and drift rates similar to bulk (wire) thermocouples. PMID:24217356

Metallic and ceramic thin film thermocouples for gas turbine engines.

PubMed

Tougas, Ian M; Amani, Matin; Gregory, Otto J

2013-11-08

Temperatures of hot section components in today's gas turbine engines reach as high as 1,500 °C, making in situ monitoring of the severe temperature gradients within the engine rather difficult. Therefore, there is a need to develop instrumentation (i.e., thermocouples and strain gauges) for these turbine engines that can survive these harsh environments. Refractory metal and ceramic thin film thermocouples are well suited for this task since they have excellent chemical and electrical stability at high temperatures in oxidizing atmospheres, they are compatible with thermal barrier coatings commonly employed in today's engines, they have greater sensitivity than conventional wire thermocouples, and they are non-invasive to combustion aerodynamics in the engine. Thin film thermocouples based on platinum:palladium and indium oxynitride:indium tin oxynitride as well as their oxide counterparts have been developed for this purpose and have proven to be more stable than conventional type-S and type-K thin film thermocouples. The metallic and ceramic thin film thermocouples described within this paper exhibited remarkable stability and drift rates similar to bulk (wire) thermocouples.

Development of Novel Magnetic Metal Oxide Films and Carbon Nanotube Materials for Magnetic Device Applications

DTIC Science & Technology

2015-01-23

From these studies we learned that nano wires of Fe grown in the lumens of multi-walled carbon nanotubes ( MWCNTs ) required four times higher 35...studies we learned that nano wires of Fe grown in the lumens of multi-walled carbon nanotubes ( MWCNTs ) required four times higher magnetic field...properties of nano-metric Fe thin films on 325 MgO(100) and nano wires of Fe prepared in the lumens of MWCNTs using magnetron DC-sputtering were studied

Effect of thickness of insulation coating on temperature of electrically exploded tungsten wires in vacuum

NASA Astrophysics Data System (ADS)

Shi, Huantong; Zou, Xiaobing; Wang, Xinxin

2017-07-01

This paper reports an interesting observation of great differences in the temperature of exploded wires with insulation coating of different thicknesses. Two kinds of polyimide-coated tungsten wires were used with the same conductive diameter 12.5 μm but a different thickness of coating, 0.75-2.25 μm and 2.25-4.25 μm, respectively. The specific energy reconstructed from the current and voltage signals was quite close for the tested wires. However, the exploding scenario, obtained from Mach-Zehnder interferograms, showed great differences: a neutral outer-layer was observed around the thick-coated wire, which was absent for the thin-coated wire; and the calculated electron density and local thermal equilibrium temperature were much higher for thick-coated wires. The heat-preserving neutral layer formed by the decomposition of the insulation was supposed to be the cause of this phenomenon.

Aircraft Electromagnetic Compatibility.

DTIC Science & Technology

1987-06-01

Human Exposure to Radio Frequency Electromagnetic Fields , 300 KiloHertz to 100 GigaHertz." 6. ARINC 429-8, "Digital Information Transfer System (DITS...142 V EXECUTIVE SUMMARY The Aircraft Electromagnetic Compatibility guidelines document deals with electromagnetic compatibility in a... electromagnetic interference paths (figure EI. TYPE PATH 400 Hz Electrostatic MagneticCharge Electric Field Transients 5 R d t Coupling 150/i 300o Wire

The Heliopause Electrostatic Rapid Transit System (HERTS) Design, Trades, and Analyses Performed in the First Year of a Two Year Investigation

NASA Technical Reports Server (NTRS)

Wiegmann, Bruce M.

2016-01-01

The Heliopause Electrostatic Rapid Transit System (HERTS)1 was one of the seven total Phase II NASA Innovative Advanced Concepts (NIAC) that was down-selected in 2015 for continued funding and research. In Phase I we learned that a spacecraft propelled by an Electric Sail (E-Sail) can travel great astronomical distances, such as to the Heliopause region of the solar system (approx.100 to 120 AU) in approximately one quarter of the time (10 years) versus the time it took the Voyager spacecraft launched in 1977 (36 years). The current work within the Phase II NIAC effort builds upon the work that was done in the Phase I NIAC and is focused on: 1) Testing of plasma interaction with a charged wire in a unique MSFC test chamber, 2) Development of a Particle-in-Cell (PIC) models that are validated in the plasma testing and used to extrapolate to the E-Sail propulsion system design. 3) Further down select of a wire deployment and control approach from those narrowed down in the Phase I effort. This paper will document the findings to date (June, 2016) of the above focused areas.

Toward self-assembled ferroelectric random access memories: hard-wired switching capacitor arrays with almost Tb/in.(2) densities.

PubMed

Evans, Paul R; Zhu, Xinhau; Baxter, Paul; McMillen, Mark; McPhillips, John; Morrison, Finlay D; Scott, James F; Pollard, Robert J; Bowman, Robert M; Gregg, J Marty

2007-05-01

We report on the successful fabrication of arrays of switchable nanocapacitors made by harnessing the self-assembly of materials. The structures are composed of arrays of 20-40 nm diameter Pt nanowires, spaced 50-100 nm apart, electrodeposited through nanoporous alumina onto a thin film lower electrode on a silicon wafer. A thin film ferroelectric (both barium titanate (BTO) and lead zirconium titanate (PZT)) has been deposited on top of the nanowire array, followed by the deposition of thin film upper electrodes. The PZT nanocapacitors exhibit hysteresis loops with substantial remnant polarizations, while although the switching performance was inferior, the low-field characteristics of the BTO nanocapacitors show dielectric behavior comparable to conventional thin film heterostructures. While registration is not sufficient for commercial RAM production, this is nevertheless an embryonic form of the highest density hard-wired FRAM capacitor array reported to date and compares favorably with atomic force microscopy read-write densities.

Giant magnetic impedance of wires with a thin magnetic coating

NASA Astrophysics Data System (ADS)

Kurlyandskaya, G. V.; Bebenin, N. G.; Vas'kovsky, V. O.

2011-02-01

In this review, we analyzed and generalized the results of experimental investigations of physical processes that occur in composite wires with a thin magnetic coating under the conditions of the appearance in them of a giant magnetoimpedance (GMI) effect. Principles of the measurements of high-frequency impedance are described in short; basic definitions are given, and the differences in the linear and nonlinear GMI regimes are described. Data are systemized on the giant magnetic impedance of wires with a thin magnetic coating (composite materials) under the conditions of a strong nonlinearity of the GMI effect, which is accompanied by the appearance of higher harmonics in the output signal. The extremely high susceptibility of the harmonic parameters to external actions can be used in the technical applications for creating ultrasensitive detectors of low magnetic fields. Special attention is paid to model calculations, which confirm the fact that the experimentally observed features of a nonlinear GMI effect are connected with the high sensitivity of the magnetic system to a circular magnetic field near the spin-reorientation phase transitions. Fine features of the effective magnetic anisotropy can play the key role and therefore cannot be ignored in the general case.

Time domain analysis of thin-wire antennas over lossy ground using the reflection-coefficient approximation

NASA Astrophysics Data System (ADS)

FernáNdez Pantoja, M.; Yarovoy, A. G.; Rubio Bretones, A.; GonzáLez GarcíA, S.

2009-12-01

This paper presents a procedure to extend the methods of moments in time domain for the transient analysis of thin-wire antennas to include those cases where the antennas are located over a lossy half-space. This extended technique is based on the reflection coefficient (RC) approach, which approximates the fields incident on the ground interface as plane waves and calculates the time domain RC using the inverse Fourier transform of Fresnel equations. The implementation presented in this paper uses general expressions for the RC which extend its range of applicability to lossy grounds, and is proven to be accurate and fast for antennas located not too near to the ground. The resulting general purpose procedure, able to treat arbitrarily oriented thin-wire antennas, is appropriate for all kind of half-spaces, including lossy cases, and it has turned out to be as computationally fast solving the problem of an arbitrary ground as dealing with a perfect electric conductor ground plane. Results show a numerical validation of the method for different half-spaces, paying special attention to the influence of the antenna to ground distance in the accuracy of the results.

Conceptual Design of an Electric Sail Technology Demonstration Mission Spacecraft

NASA Technical Reports Server (NTRS)

Wiegmann, Bruce M.

2017-01-01

There is great interest in examining the outer planets of our solar system and Heliopause region (edge of Solar System) and beyond regions of interstellar space by both the Planetary and Heliophysics communities. These needs are well docu-mented in the recent National Academy of Sciences Decadal Surveys. There is significant interest in developing revolutionary propulsion techniques that will enable such Heliopause scientific missions to be completed within 10 to15 years of the launch date. One such enabling propulsion technique commonly known as Electric Sail (E-Sail) propulsion employs positively charged bare wire tethers that extend radially outward from a rotating spacecraft spinning at a rate of one revolution per hour. Around the positively charged bare-wire tethers, a Debye Sheath is created once positive voltage is applied. This sheath stands off of the bare wire tether at a sheath diameter that is proportional to the voltage in the wire coupled with the flux density of solar wind ions within the solar system (or the location of spacecraft in the solar system. The protons that are expended from the sun (solar wind) at 400 to 800 km/sec are electrostatically repelled away from these positively charged Debye sheaths and propulsive thrust is produced via the resulting momentum transfer. The amount of thrust produced is directly proportional to the total wire length. The Marshall Space Flight Center (MSFC) Electric Sail team is currently funded via a two year Phase II NASA Innovative Advanced Concepts (NIAC) awarded in July 2015. The team's current activities are: 1) Developing a Particle in Cell (PIC) numeric engineering model from the experimental data collected at MSFC's Solar Wind Facility on the interaction between simulated solar wind interaction with a charged bare wire that can be applied to a variety of missions, 2) The development of the necessary tether deployers and tethers to enable successful de-ployment of multiple, multi km length bare tethers, 3) Controllability of the space-craft via a voltage bias to steer itself through the solar system to destinations of discovery. These activities once demonstrated analytically, will require a technology demonstration mission (TDM) around the year2020 to demonstrate that all systems work together seamlessly before a Heliophysics Electrostatic Rapid Transit System (HERTS) mission could be initiated. A notional TDM spacecraft that meets the requirements of such a mission will be showcased in this paper.

Method of forming low cost, formable High T(subc) superconducting wire

NASA Technical Reports Server (NTRS)

Smialek, James L. (Inventor)

1989-01-01

A ceramic superconductivity part, such as a wire, is produced through the partial oxidation of a specially formulated copper alloy in a core. The alloys contains low level of quantities of rare earth and alkaline earth dopant elements. Upon oxidation at high temperatures, and superconducting oxide phases are formed as a thin film.

FUEL ELEMENT AND METHOD OF PREPARATION

DOEpatents

Kingston, W.E.

1961-04-25

A nuclear fuel element in the form of a wire is reported. A bar of uranium is enclosed in a thin layer of aluminum and the composite is sheathed in beryllium, zirconium, or stainnless steel. The sheathed article is then drawn to wire form, heated to alloy the aluminum with both uranium and sheath, and finally cold worked.

Quantum anomalous Hall Majorana platform

NASA Astrophysics Data System (ADS)

Zeng, Yongxin; Lei, Chao; Chaudhary, Gaurav; MacDonald, Allan H.

2018-02-01

We show that quasi-one-dimensional quantum wires can be written onto the surface of magnetic topological insulator (MTI) thin films by gate arrays. When the MTI is in a quantum anomalous Hall state, MTI/superconductor quantum wires have especially broad stability regions for both topological and nontopological states, facilitating creation and manipulation of Majorana particles on the MTI surface.

The effect of split gate dimensions on the electrostatic potential and 0.7 anomaly within one-dimensional quantum wires on a modulation doped GaAs/AlGaAs heterostructure

NASA Astrophysics Data System (ADS)

Smith, L. W.; Al-Taie, H.; Lesage, A. A. J.; Thomas, K. J.; Sfigakis, F.; See, P.; Griffiths, J. P.; Farrer, I.; Jones, G. A. C.; Ritchie, D. A.; Kelly, M. J.; Smith, C. G.

We use a multiplexing scheme to measure the conductance properties of 95 split gates of 7 different gate dimensions fabricated on a GaAs/AlGaAs chip, in a single cool down. The number of devices for which conductance is accurately quantized reduces as the gate length increases. However, even the devices for which conductance is accurately quantized in units of 2e2 / h show no correlation between the length of electrostatic potential barrier in the channel and the gate length, using a saddle point model to estimate the barrier length. Further, the strength of coupling between the gates and the 1D channel does not increase with gate length beyond 0.7 μm. The background electrostatic profile appears as significant as the gate dimension in determining device behavior. We find a clear correlation between the curvature of the electrostatic barrier along the channel and the strength of the ``0.7 anomaly'' which identifies the electrostatic length of the channel as the principal factor governing the conductance of the 0.7 anomaly. Present address: Wisconsin Institute for Quantum Information, University of Wisconsin-Madison, Madison, WI.

Quantum oscillation and the Aharonov-Bohm effect in a multiply connected normal-conductor loop

NASA Astrophysics Data System (ADS)

Takai, Daisuke; Ohta, Kuniichi

1994-12-01

The magnetostatic and electrostatic Aharonov-Bohm (AB) effects in multiply connected normal-conductor rings are studied. A previously developed model of a single mesoscopic ring is generalized to include an arbitrary number of rings, and the oscillatory behavior of the total transmission coefficients for the serially connected N (N is equal to integer) rings are derived as a function of the magnetic flux threading each ring and as a function of the electrostatic potential applied to the rings. It is shown that quantum oscillation of multiple rings exhibits greater variety of behavior than in periodic superlattices. We investigate the influence of the scattering at a junction and the number of atoms in the ring in both magnetostatic and electrostatic oscillation of multiring systems. For the electrostatic AB effects, when scattering occurs at the junctions between the connecting wire and the ring, the conductance in the AB oscillation is modified to an N-1 peaked shape. It is shown that this oscillatory behavior is greatly influenced by the number of atoms in the ring and is controlled by the electrostatic potential or magnetic flux that is applied to the ring. We discuss the behavior of the quantum oscillations upon varying the number of connected rings and the number of minibands.

Thermal Testing and Integration: Magnetospheric MultiScale (MMS) Observatories with Digital 1-Wire Sensors

NASA Technical Reports Server (NTRS)

Solimani, Jason A.; Rosanova, Santino

2015-01-01

Thermocouples require two thin wires to be routed out of the spacecraft to connect to the ground support equipment used to monitor and record the temperature data. This large number of wires that exit the observatory complicates integration and creates an undesirable heat path during testing. These wires exiting the spacecraft need to be characterized as a thermal short that will not exist during flight. To minimize complexity and reduce thermal variables from these ground support equipment (GSE) wires, MMS pursued a hybrid path for temperature monitoring, utilizing thermocouples and digital 1-wire temperature sensors. Digital 1-wire sensors can greatly reduce harness mass, length and complexity as they can be spliced together. For MMS, 350 digital 1-wire sensors were installed on the spacecraft with only 18 wires exiting as opposed to a potential 700 thermocouple wires. Digital 1-wire sensors had not been used in such a large scale at NASAGSFC prior to the MMS mission. During the MMS thermal vacuum testing a lessons learned matrix was formulated that will assist future integration of 1-wires into thermal testing and one day into flight.

Thin film fabrication and system integration test run for a microactuator for a tuneable lens

NASA Astrophysics Data System (ADS)

Hoheisel, Dominik; Rissing, Lutz

2014-03-01

An electromagnetic microactuator, for controlling of a tuneable lens, with an integrated electrostatic element is fabricated by thin film technology. The actuator consists of two parts: the first part with microcoil and flux guide and the second part with a ring shaped back iron on a polyimide membrane. The back iron is additionally useable as electrode for electrostatic measurement of the air gap and for electrostatic actuation. By attracting the back iron an optical liquid is displaced and forms a liquid lens inside the back iron ring covered by the membrane. For testing the thin film fabrication sequence, up-scaled systems are generated in a test run. To fabricate the flux guide in an easy and quick way, a Ni-Fe foil with a thickness of 50 μm is laminated on the Si-wafer. This foil is also utilized in the following fabrication sequence as seed layer for electroplating. Compared to Ni-Fe structures deposited by electroplating, the foil is featuring better soft magnetic properties. The foil is structured by wet chemical etching and the backside of the wafer is structured by deep reactive ion etching (DRIE). For post fabrication thinning, the polyimide membrane is treated by oxygen plasma etching. To align the back iron to the microcoil and the flux guide, a flip-chip-bonder is used during test run of system integration. To adjust a constant air gap, a water solvable polymer is tested. A two component epoxy and a polyimide based glue are compared for their bonding properties of the actuator parts.

Properties of Nanocrystalline Cubic Silicon Carbide Thin Films Prepared by Hot-Wire Chemical Vapor Deposition Using SiH4/CH4/H2 at Various Substrate Temperatures

NASA Astrophysics Data System (ADS)

Tabata, Akimori; Komura, Yusuke; Hoshide, Yoshiki; Narita, Tomoki; Kondo, Akihiro

2008-01-01

Silicon carbide (SiC) thin films were prepared by hot-wire chemical vapor deposition from SiH4/CH4/H2 gases, and the influence of substrate temperature, Ts (104 < Ts < 434 °C), on the properties of the SiC thin films was investigated. X-ray diffraction patterns and Raman scattering spectra revealed that nanocrystalline cubic SiC (nc-3C-SiC) films grew at Ts above 187 °C, while completely amorphous films grew at Ts = 104 °C. Fourier transform infrared absorption spectra revealed that the crystallinity of the nc-3C-SiC was improved with increasing Ts up to 282 °C and remained almost unchanged with a further increase in Ts from 282 to 434 °C. The spin density was reduced monotonically with increasing Ts.

Radiofrequency dosimetry in subjects implanted with metallic straight wires: a numerical study.

PubMed

Mattei, E; Calcagnini, G; Censi, F; Triventi, M; Bartolini, P

2008-01-01

A numerical study to investigate the effects of the exposure to electromagnetic fields (EMF) at 900 and 1800 MHz on biological tissues implanted with thin metallic structures has been carried out, using the finite difference time domain (FDTD) solution technique. The results of the model show that the presence of a metallic wire yields to a significant increase in the local specific energy absorption rate (SAR). The present standards and/or guidelines on safe exposures of humans to EMF does not cover persons with implanted devices and thus the threshold levels to define safe exposure conditions might not apply in presence of high SAR gradients, such as the ones generated by thin metallic implanted objects. However, exposure to EMF fields below the actual safe levels even in presence of thin conductive structures cause rather low temperature rises (1 degrees C).

Imaging nanowire plasmon modes with two-photon polymerization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gruber, Christian; Trügler, Andreas; Hohenester, Ulrich

2015-02-23

Metal nanowires sustain propagating surface plasmons that are strongly confined to the wire surface. Plasmon reflection at the wire end faces and interference lead to standing plasmon modes. We demonstrate that these modes can be imaged via two-photon (plasmon) polymerization of a thin film resist covering the wires and subsequent electron microscopy. Thereby, the plasmon wavelength and the phase shift of the nanowire mode picked up upon reflection can be directly retrieved. In general terms, polymerization imaging is a promising tool for the imaging of propagating plasmon modes from the nano- to micro-scale.

Torsional Oscillations with Lorentz Force

ERIC Educational Resources Information Center

Gluck, Paul

2007-01-01

We have built a device that uses the Lorentz force on a current-carrying wire situated in a magnetic field, F = I L x B, in order to demonstrate a slowly varying alternating current by means of an optical lever. The apparatus consists of a horseshoe magnet, a length of thin enamel-coated wire (ours was 0.3 mm thick), a signal generator, a…

Electrostatic Discharge Effects on Thin Film Resistors

NASA Technical Reports Server (NTRS)

Sampson, Michael J.; Hull, Scott M.

1999-01-01

Recently, open circuit failures of individual elements in thin film resistor networks have been attributed to electrostatic discharge (ESD) effects. This paper will discuss the investigation that came to this conclusion and subsequent experimentation intended to characterize design factors that affect the sensitivity of resistor elements to ESD. The ESD testing was performed using the standard human body model simulation. Some of the design elements to be evaluated were: trace width, trace length (and thus width to length ratio), specific resistivity of the trace (ohms per square) and resistance value. However, once the experiments were in progress, it was realized that the ESD sensitivity of most of the complex patterns under evaluation was determined by other design and process factors such as trace shape and termination pad spacing. This paper includes pictorial examples of representative ESD failure sites, and provides some options for designing thin film resistors that are ESD resistant. The risks of ESD damage are assessed and handling precautions suggested.

Low Temperature Conductance of Thin Metal Wires and Films.

NASA Astrophysics Data System (ADS)

Masden, Joseph Thomas

The topic of this thesis is the study of electrical conduction in one and two dimensional systems; specifically the effects predicted by localization and electron-electron interaction theory. We have measured the resistance of wires with very small cross-sectional areas at low temperatures. We find at low temperatures that the resistance varies as T('- 1/2) and that the magnitude of the resistance rise is inversely proportional to the area, as found previously by others. From an analysis of the temperature dependence of the resistance, we find a characteristic length of 0.18 (mu)m at 1K for Pt and AuPd wires, which is the same length found by others. We have also measured the resistance of thin Pt and AuPd films and find that the resistance increases as the temperature decreases. This increase varies as the logarithm of the temperature, and the magnitude of the increase is proportional to the sheet resistance for films with sheet resistances less than about 2 K(OMEGA). A method for fabricating short wires and films was developed to determine the characteristic length by measuring the length dependence of the resistance rise. According to the theories, the behavior of the wires and films should change when the length of the wire or film is comparable to the characteristic length. For the short wires, we found this to be so, and our results are in semi-quantitative agreement with the theory. In short films, we also see an effect as the length of the film is decreased, but the results appear to be inconsistent with the theory, at least in its present form.

A new infusion pathway monitoring system utilizing electrostatic induced potential.

PubMed

Maki, Hiromichi; Yonezawa, Yoshiharu; Ogawa, Hidekuni; Ninomiya, Ishio; Sada, Kouji; Hamada, Shingo; Hahn, Alien W; Caldwell, W Morton

2006-01-01

We have developed a new infusion pathway monitoring system employing linear integrated circuits and a low-power 8-bit single chip microcomputer. The system is available for hospital and home use and it constantly monitors the intactness of the pathway. The sensor is an electro-conductive polymer electrode wrapped around the infusion polyvinyl chloride infusion tube. This records an AC (alternating current) voltage induced on the patient's body by electrostatic coupling from the normal 100 volt, 60 Hz AC power line wiring field in the patient's room. If the injection needle or infusion tube becomes detached, then the system detects changes in the induced AC voltage and alerts the nursing station, via the nurse call system or PHS (personal handy phone System).

Study and Construction of Electrostatic Biprisms Useful in Corpuscular Optics; ETUDE ET REALISATION DE BIPRISMES ELECTROSTATIQUES UTILISABLES EN OPTIQUE CORPUSCULAIRE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Septier, A.

1960-03-01

In the simultaneous injection of two beams identical except in direction in an FFAG cyclotron, two beams of equal intensity and energy are needed. The two beams can be produced either by alternating the direction of a single beam by very short, rectangular, high-voltage pulses fed to a deflector, or by chopping the beam with a static apparatus. The second method was investigated because of its simplicity. The principles and properties of the electrostatic biprism are presented. Three cases are then considered: a wire stretched between two plates, a grid between two plates, and a plate between two flat conductors.more » (T.R.H.)« less

Development of an electrostatic dust detector for tungsten dust

NASA Astrophysics Data System (ADS)

Starkey, D.; Hammond, K.; Roquemore, L.; Skinner, C. H.

2012-10-01

Next-step fusion reactors, such as ITER, are expected to have large quantities of dust that will present hazards that have yet to be encountered in current fusion devices. To manage the amount of dust within the reactors a real-time dust detector must be implemented to ensure that dust does not reach hazardous levels. An electrostatic device that accomplishes this has already been tested on NSTX and Tore Supra [1,2]. We will present modifications of this device to improve its ruggedness to withstand the conditions that will be present in ITER. The detector consists of two tungsten wires wrapped around a macor cylinder that are biased at 100-300 V. Incident dust causes a measurable transient short circuit. Initial results have demonstrated the detection of tungsten particles. We will also present a potential method of electrostatic cleaning of residual dust from the detector.[4pt] [1] C. H. Skinner et al., Rev. Sci. Instrum., 81, 10E102 (2010)[0pt] [2] H. Roche et al., Phys. Scr., T145, (2011).

Self-surface charge exfoliation and electrostatically coordinated 2D hetero-layered hybrids

PubMed Central

Yang, Min-Quan; Xu, Yi-Jun; Lu, Wanheng; Zeng, Kaiyang; Zhu, Hai; Xu, Qing-Hua; Ho, Ghim Wei

2017-01-01

At present, the technological groundwork of atomically thin two-dimensional (2D) hetero-layered structures realized by successive thin film epitaxial growth is in principle constrained by lattice matching prerequisite as well as low yield and expensive production. Here, we artificially coordinate ultrathin 2D hetero-layered metal chalcogenides via a highly scalable self-surface charge exfoliation and electrostatic coupling approach. Specifically, bulk metal chalcogenides are spontaneously exfoliated into ultrathin layers in a surfactant/intercalator-free medium, followed by unconstrained electrostatic coupling with a dissimilar transition metal dichalcogenide, MoSe2, into scalable hetero-layered hybrids. Accordingly, surface and interfacial-dominated photocatalysis reactivity is used as an ideal testbed to verify the reliability of diverse 2D ultrathin hetero-layered materials that reveal high visible-light photoreactivity, efficient charge transfer and intimate contact interface for stable cycling and storage purposes. Such a synthetic approach renders independent thickness and composition control anticipated to advance the development of ‘design-and-build' 2D layered heterojunctions for large-scale exploration and applications. PMID:28146147

Aeroelastic flutter energy harvesters self-polarized by triboelectric effects

NASA Astrophysics Data System (ADS)

Perez, M.; Boisseau, S.; Geisler, M.; Gasnier, P.; Willemin, J.; Despesse, G.; Reboud, J. L.

2018-01-01

This paper presents the performances of several electrostatic flutter energy harvesters tested in a wind tunnel between 0 and 20 m s-1. The main idea is to use the flutter capability of thin flexible films confined between lateral walls to induce simultaneously the capacitance variations and the electrostatic polarization required by the triboelectric/electrostatic conversion. This technology provides thin and flexible devices and solve the electret’s stability issue (Perez et al 2015 Smart Mater. Struct., Perez et al 2015 New Circuits and Systems). Our prototypes (<16 cm2) have a quick startup (from 3 m s-1) and an electrical power-flux density from 0.35 μW cm-2@3 m s-1 (light breeze) to 35 μW cm-2@20 m s-1 (fresh gale). A Maximum Power Point circuit has been developed to efficiently use the power provided by the energy harvesters. The energy harvester combined with its power management circuit has finally been used to supply an 868 MHz wireless sensor node with temperature and acceleration measurements, validating the complete energy harvesting chain.

Electrostatic and aerodynamic forced vibrations of a thin flexible electrode: Quasi-periodic vs. chaotic oscillations.

PubMed

Madanu, Sushma B; Barbel, Stanley I; Ward, Thomas

2016-06-01

In this paper, transverse vibrations of an electrostatically actuated thin flexible cantilever perturbed by low-speed air flow are studied using both experiments and numerical modeling. In the experiments, the dynamic characteristics of the cantilever are studied by supplying a DC voltage with an AC component for electrostatic forcing and a constant uniform air flow around the cantilever system for aerodynamic forcing. A range of control parameters leading to stable vibrations are established using a dimensionless operating parameter that is the ratio of the induced and the free stream velocities. Numerical results are validated with experimental data. Assuming the amplitude of vibrations are small, then a non-linear dynamic Euler-Bernoulli beam equation with viscous damping and gravitational effects is used to model the equation of motion. Aerodynamic forcing is modelled as a temporally sinusoidal and uniform force acting perpendicular to the beam length. The forcing amplitude is found to be proportional to the square of the air flow velocity. Numerical results strongly agree with the experiments predicting accurate vibration amplitude, displacement frequency, and quasi-periodic displacement of the cantilever tip.

Electrostatic testing of thin plastic materials

NASA Technical Reports Server (NTRS)

Skinner, S. Ballou

1988-01-01

Ten thin plastic materials (Velostat, RCAS 1200, Llumalloy, Herculite 80, RCAS 2400, Wrightlon 7000, PVC, Aclar 22A, Mylar, and Polyethylene) were tested for electrostatic properties by four different devices: (1) The static decay meter, (2) the manual triboelectric testing device, (3) the robotic triboelectric testing device, and (4) the resistivity measurement adapter device. The static decay meter measured the electrostatic decay rates in accordance with the Federal Test Method Standard 101B, Method 4046. The manual and the robotic triboelectric devices measured the triboelectric generated peak voltages and the five-second decay voltages in accordance with the criteria for acceptance standards at Kennedy Space Center. The resistivity measurement adapter measured the surface resistivity of each material. An analysis was made to correlate the data among the four testing devices. For the material tested the pass/fail results were compared for the 4046 method and the triboelectric testing devices. For the limited number of materials tested, the relationship between decay rate and surface resistivity was investigated as well as the relationship between triboelectric peak voltage and surface resistivity.

Thermal conductance of Nb thin films at sub-kelvin temperatures

PubMed Central

Feshchenko, A. V.; Saira, O.-P.; Peltonen, J. T.; Pekola, J. P.

2017-01-01

We determine the thermal conductance of thin niobium (Nb) wires on a silica substrate in the temperature range of 0.1–0.6 K using electron thermometry based on normal metal-insulator-superconductor tunnel junctions. We find that at 0.6 K, the thermal conductance of Nb is two orders of magnitude lower than that of Al in the superconducting state, and two orders of magnitude below the Wiedemann-Franz conductance calculated with the normal state resistance of the wire. The measured thermal conductance exceeds the prediction of the Bardeen-Cooper-Schrieffer theory, and demonstrates a power law dependence on temperature as T4.5, instead of an exponential one. At the same time, we monitor the temperature profile of the substrate along the Nb wire to observe possible overheating of the phonon bath. We show that Nb can be successfully used for thermal insulation in a nanoscale circuit while simultaneously providing an electrical connection. PMID:28155895

Thermal conductivity measurement of fluids using the 3ω method

NASA Astrophysics Data System (ADS)

Lee, Seung-Min

2009-02-01

We have developed a procedure to measure the thermal conductivity of dielectric liquids and gases using a steady state ac hot wire method in which a thin metal wire is used as a heater and thermometer. The temperature response of the heater wire was measured in a four-probe geometry using an electronic circuit developed for the conventional 3ω method. The measurements have been performed in the frequency range from 1 mHz to 1 kHz. We devised a method to transform the raw data into well-known linear logarithmic frequency dependence plot. After the transformation, an optimal frequency region of the thermal conductivity data was clearly determined as has been done with the data from thin metal film heater. The method was tested with air, water, ethanol, mono-, and tetraethylene glycol. Volumetric heat capacity of the fluids was also calculated with uncertainty and the capability as a probe for metal-liquid thermal boundary conductance was discussed.

Improved superconducting magnet wire

DOEpatents

Schuller, I.K.; Ketterson, J.B.

1983-08-16

This invention is directed to a superconducting tape or wire composed of alternating layers of copper and a niobium-containing superconductor such as niobium of NbTi, Nb/sub 3/Sn or Nb/sub 3/Ge. In general, each layer of the niobium-containing superconductor has a thickness in the range of about 0.05 to 1.5 times its coherence length (which for Nb/sub 3/Si is 41 A) with each copper layer having a thickness in the range of about 170 to 600 A. With the use of very thin layers of the niobium composition having a thickness within the desired range, the critical field (H/sub c/) may be increased by factors of 2 to 4. Also, the thin layers of the superconductor permit the resulting tape or wire to exhibit suitable ductility for winding on a magnet core. These compositions are also characterized by relatively high values of critical temperature and therefore will exhibit a combination of useful properties as superconductors.

Electrostatically driven fog collection using space charge injection

PubMed Central

Damak, Maher; Varanasi, Kripa K.

2018-01-01

Fog collection can be a sustainable solution to water scarcity in many regions around the world. Most proposed collectors are meshes that rely on inertial collision for droplet capture and are inherently limited by aerodynamics. We propose a new approach in which we introduce electrical forces that can overcome aerodynamic drag forces. Using an ion emitter, we introduce a space charge into the fog to impart a net charge to the incoming fog droplets and direct them toward a collector using an imposed electric field. We experimentally measure the collection efficiency on single wires, two-wire systems, and meshes and propose a physical model to quantify it. We identify the regimes of optimal collection and provide insights into designing effective fog harvesting systems. PMID:29888324

Triboelectret-based aeroelastic flutter energy harvesters

NASA Astrophysics Data System (ADS)

Perez, Matthias; Boisseau, Sebastien; Geisler, Matthias; Despesse, Ghislain; Reboud, Jean Luc

2016-11-01

This paper highlights some experimental results on several electrostatic membranes tested in a wind tunnel between 0 and 20m.s-1 for airflow energy harvesting. The main idea is to use the aeroelastic behavior of thin flexible films to induce simultaneously the capacitance variations and the polarization required by the triboelectric/electrostatic conversion. This technology provides thin and flexible devices and avoids the issue of electrets discharge. Our prototypes (<16cm2) allowed a quick startup (from 3ms-1), an electrical power-flux density from 0.1μW.cm-2 to 60μW.cm-2. In order to complete the energy harvesting chain, we have used a wireless sensor with temperature and acceleration measures coupled to a low power transmission (Bluetooth Low Energy) with reception on a smartphone.

Charge retention behavior of preferentially oriented and textured Bi3.25La0.75Ti3O12 thin films by electrostatic force microscopy

NASA Astrophysics Data System (ADS)

Kim, T. Y.; Lee, J. H.; Oh, Y. J.; Choi, M. R.; Jo, W.

2007-02-01

The authors report charge retention in preferentially (117) oriented and textured c-axis oriented ferroelectric Bi3.25La0.75Ti3O12 thin films by electrostatic force microscopy. Surface charges of the films were observed as a function of time in a selected area which consists of a single-poled region and a reverse-poled region. The highly (117) oriented film shows the extended exponential decay with characteristic scaling exponents, n =1.5-1.6. The preferentially c-axis oriented film shows a remarkable retained behavior regardless of the poling. Decay and retention mechanisms of the regions are explained by space-charge redistribution and trapping of defects in the films.

Feasibility study of an active soft catheter actuated by SMA wires

NASA Astrophysics Data System (ADS)

Konh, Bardia; Karimi, Saeed; Miller, Scott

2018-03-01

This study aims to assess the feasibility of using a combination of thin elastomer tubes and SMA wires to develop an active catheter. Cardiac catheters have been widely used in investigational and interventional procedures such as angiography, angioplasty, electro- physiology, and endocardial ablation. The commercial models manually steer inside the patient's body via internally installed pull wires. Active catheters, on the other hand, have the potential to revolutionize surgical procedures because of their computer-controlled and enhanced motion. Shape memory alloys have been used for almost a decade as a trustworthy actuator for biomedical applications. In this work, SMA wires were attached to a small pressurized elastomer tube to realize deflection. The tube was pressurized to maintain a constant stress on the SMA wires. The tip motion via actuation of SMA wires was then measured and reported. The results of this study showed that by adopting an appropriate training process for the SMA wires prior to performing the experiments and adopting an appropriate internal pressure for the elastomer tube, less external loads on SMA wires would be needed for a consistent actuation.

Gate tunable parallel double quantum dots in InAs double-nanowire devices

NASA Astrophysics Data System (ADS)

Baba, S.; Matsuo, S.; Kamata, H.; Deacon, R. S.; Oiwa, A.; Li, K.; Jeppesen, S.; Samuelson, L.; Xu, H. Q.; Tarucha, S.

2017-12-01

We report fabrication and characterization of InAs nanowire devices with two closely placed parallel nanowires. The fabrication process we develop includes selective deposition of the nanowires with micron scale alignment onto predefined finger bottom gates using a polymer transfer technique. By tuning the double nanowire with the finger bottom gates, we observed the formation of parallel double quantum dots with one quantum dot in each nanowire bound by the normal metal contact edges. We report the gate tunability of the charge states in individual dots as well as the inter-dot electrostatic coupling. In addition, we fabricate a device with separate normal metal contacts and a common superconducting contact to the two parallel wires and confirm the dot formation in each wire from comparison of the transport properties and a superconducting proximity gap feature for the respective wires. With the fabrication techniques established in this study, devices can be realized for more advanced experiments on Cooper-pair splitting, generation of Parafermions, and so on.

Homogenized boundary conditions and resonance effects in Faraday cages

PubMed Central

Hewitt, I. J.

2016-01-01

We present a mathematical study of two-dimensional electrostatic and electromagnetic shielding by a cage of conducting wires (the so-called ‘Faraday cage effect’). Taking the limit as the number of wires in the cage tends to infinity, we use the asymptotic method of multiple scales to derive continuum models for the shielding, involving homogenized boundary conditions on an effective cage boundary. We show how the resulting models depend on key cage parameters such as the size and shape of the wires, and, in the electromagnetic case, on the frequency and polarization of the incident field. In the electromagnetic case, there are resonance effects, whereby at frequencies close to the natural frequencies of the equivalent solid shell, the presence of the cage actually amplifies the incident field, rather than shielding it. By appropriately modifying the continuum model, we calculate the modified resonant frequencies, and their associated peak amplitudes. We discuss applications to radiation containment in microwave ovens and acoustic scattering by perforated shells. PMID:27279775

Homogenized boundary conditions and resonance effects in Faraday cages

NASA Astrophysics Data System (ADS)

Hewett, D. P.; Hewitt, I. J.

2016-05-01

We present a mathematical study of two-dimensional electrostatic and electromagnetic shielding by a cage of conducting wires (the so-called `Faraday cage effect'). Taking the limit as the number of wires in the cage tends to infinity, we use the asymptotic method of multiple scales to derive continuum models for the shielding, involving homogenized boundary conditions on an effective cage boundary. We show how the resulting models depend on key cage parameters such as the size and shape of the wires, and, in the electromagnetic case, on the frequency and polarization of the incident field. In the electromagnetic case, there are resonance effects, whereby at frequencies close to the natural frequencies of the equivalent solid shell, the presence of the cage actually amplifies the incident field, rather than shielding it. By appropriately modifying the continuum model, we calculate the modified resonant frequencies, and their associated peak amplitudes. We discuss applications to radiation containment in microwave ovens and acoustic scattering by perforated shells.

Homogenized boundary conditions and resonance effects in Faraday cages.

PubMed

Hewett, D P; Hewitt, I J

2016-05-01

We present a mathematical study of two-dimensional electrostatic and electromagnetic shielding by a cage of conducting wires (the so-called 'Faraday cage effect'). Taking the limit as the number of wires in the cage tends to infinity, we use the asymptotic method of multiple scales to derive continuum models for the shielding, involving homogenized boundary conditions on an effective cage boundary. We show how the resulting models depend on key cage parameters such as the size and shape of the wires, and, in the electromagnetic case, on the frequency and polarization of the incident field. In the electromagnetic case, there are resonance effects, whereby at frequencies close to the natural frequencies of the equivalent solid shell, the presence of the cage actually amplifies the incident field, rather than shielding it. By appropriately modifying the continuum model, we calculate the modified resonant frequencies, and their associated peak amplitudes. We discuss applications to radiation containment in microwave ovens and acoustic scattering by perforated shells.

Method of sealing

DOEpatents

Groh, Edward F.; Cassidy, Dale A.

1978-01-01

A thermocouple lead or other small diameter wire, cable or tube is passed through a thin material such as sheet metal and sealed thereinto by drawing complementary longitudinally angled, laterally rounded grooves terminating at their base ends in a common plane in both sides of the thin material with shearing occuring at the deep end faces thereof to form a rounded opening in the thin material substantially perpendicular to the plane of the thin material, passing a thermocouple lead or similar object through the opening so formed and sealing the opening with a sealant which simultaneously bonds the lead to the thin material.

N ,N'-dimethylperylene-3,4,9,10-bis(dicarboximide) on alkali halide (001) surfaces

NASA Astrophysics Data System (ADS)

Fendrich, Markus; Lange, Manfred; Weiss, Christian; Kunstmann, Tobias; Möller, Rolf

2009-05-01

The growth of N ,N'-dimethylperylene-3,4,9,10-bis(dicarboximide) (DiMe-PTCDI) on KBr(001) and NaCl(001) surfaces has been studied. Experimental results have been achieved using frequency modulation atomic force microscopy at room temperature under ultrahigh vacuum conditions. On both substrates, DiMe-PTCDI forms molecular wires with a width of 10nm, typically, and a length of up to 600nm at low coverages. All wires grow along either the [110] direction (or [11¯0] direction, respectively) of the alkali halide (001) substrates. There is no wetting layer of molecules: atomic resolution of the substrates can be achieved between the wires. The wires are mobile on KBr but substantially more stable on NaCl. A p(2×2) superstructure in a brickwall arrangement on the ionic crystal surfaces is proposed based on electrostatic considerations. Calculations and Monte Carlo simulations using empirical potentials reveal possible growth mechanisms for molecules within the first layer for both substrates, also showing a significantly higher binding energy for NaCl(001). For KBr, the p(2×2) superstructure is confirmed by the simulations; for NaCl, a less dense, incommensurate superstructure is predicted.

IC layout adjustment method and tool for improving dielectric reliability at interconnects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kahng, Andrew B.; Chan, Tuck Boon

Method for adjusting a layout used in making an integrated circuit includes one or more interconnects in the layout that are susceptible to dielectric breakdown are selected. One or more selected interconnects are adjusted to increase via to wire spacing with respect to at least one via and one wire of the one or more selected interconnects. Preferably, the selecting analyzes signal patterns of interconnects, and estimates the stress ratio based on state probability of routed signal nets in the layout. An annotated layout is provided that describes distances by which one or more via or wire segment edges aremore » to be shifted. Adjustments can include thinning and shifting of wire segments, and rotation of vias.« less

Variable stiffness sandwich panels using electrostatic interlocking core

NASA Astrophysics Data System (ADS)

Heath, Callum J. C.; Bond, Ian P.; Potter, Kevin D.

2016-04-01

Structural topology has a large impact on the flexural stiffness of a beam structure. Reversible attachment between discrete substructures allows for control of shear stress transfer between structural elements, thus stiffness modulation. Electrostatic adhesion has shown promise for providing a reversible latching mechanism for controllable internal connectivity. Building on previous research, a thin film copper polyimide laminate has been used to incorporate high voltage electrodes to Fibre Reinforced Polymer (FRP) sandwich structures. The level of electrostatic holding force across the electrode interface is key to the achievable level of stiffness modulation. The use of non-flat interlocking core structures can allow for a significant increase in electrode contact area for a given core geometry, thus a greater electrostatic holding force. Interlocking core geometries based on cosine waves can be Computer Numerical Control (CNC) machined from Rohacell IGF 110 Foam core. These Interlocking Core structures could allow for enhanced variable stiffness functionality compared to basic planar electrodes. This novel concept could open up potential new applications for electrostatically induced variable stiffness structures.

Ecofriendly and Nonvacuum Electrostatic Spray-Assisted Vapor Deposition of Cu(In,Ga)(S,Se)2 Thin Film Solar Cells.

PubMed

Hossain, Md Anower; Wang, Mingqing; Choy, Kwang-Leong

2015-10-14

Chalcopyrite Cu(In,Ga)(S,Se)2 (CIGSSe) thin films have been deposited by a novel, nonvacuum, and cost-effective electrostatic spray-assisted vapor deposition (ESAVD) method. The generation of a fine aerosol of precursor solution, and their controlled deposition onto a molybdenum substrate, results in adherent, dense, and uniform Cu(In,Ga)S2 (CIGS) films. This is an essential tool to keep the interfacial area of thin film solar cells to a minimum value for efficient charge separation as it helps to achieve the desired surface smoothness uniformity for subsequent cadmium sulfide and window layer deposition. This nonvacuum aerosol based approach for making the CIGSSe film uses environmentally benign precursor solution, and it is cheaper for producing solar cells than that of the vacuum-based thin film solar technology. An optimized CIGSSe thin film solar cell with a device configuration of molybdenum-coated soda-lime glass substrate/CIGSSe/CdS/i-ZnO/AZO shows the photovoltaic (j-V) characteristics of Voc=0.518 V, jsc=28.79 mA cm(-2), fill factor=64.02%, and a promising power conversion efficiency of η=9.55% under simulated AM 1.5 100 mW cm(-2) illuminations, without the use of an antireflection layer. This demonstrates the potential of ESAVD deposition as a promising alternative approach for making thin film CIGSSe solar cells at a lower cost.

Design and Fabrication of Electrostatically Actuated Silicon Microshutters Arrays

NASA Technical Reports Server (NTRS)

Oh, L.; Li, M.; Kim, K.; Kelly, D.; Kutyrev, A.; Moseley, S.

2017-01-01

We have developed a new fabrication process to actuate microshutter arrays (MSA) electrostatically at NASA Goddard Space Flight Center. The microshutters are fabricated on silicon with thin silicon nitride membranes. A pixel size of each microshutter is 100 x 200 micrometers 2. The microshutters rotate 90 degrees on torsion bars. The selected microshutters are actuated, held, and addressed electrostatically by applying voltages on the electrodes the front and back sides of the microshutters. The atomic layer deposition (ALD) of aluminum oxide was used to insulate electrodes on the back side of walls; the insulation can withstand over 100 V. The ALD aluminum oxide is dry etched, and then the microshutters are released in vapor HF.

Beam property measurement of a 300-kV ion source test stand for a 1-MV electrostatic accelerator

NASA Astrophysics Data System (ADS)

Park, Sae-Hoon; Kim, Dae-Il; Kim, Yu-Seok

2016-09-01

The KOMAC (Korea Multi-purpose Accelerator Complex) has been developing a 300-kV ion source test stand for a 1-MV electrostatic accelerator for industrial purposes. A RF ion source was operated at 200 MHz with its matching circuit. The beam profile and emittance were measured behind an accelerating column to confirm the beam property from the RF ion source. The beam profile was measured at the end of the accelerating tube and at the beam dump by using a beam profile monitor (BPM) and wire scanner. An Allison-type emittance scanner was installed behind the beam profile monitor (BPM) to measure the beam density in phase space. The measurement results for the beam profile and emittance are presented in this paper.

Review and perspectives of electrostatic turbulence and transport studies in the basic plasma physics device TORPEX

NASA Astrophysics Data System (ADS)

Avino, Fabio; Bovet, Alexandre; Fasoli, Ambrogio; Furno, Ivo; Gustafson, Kyle; Loizu, Joaquim; Ricci, Paolo; Theiler, Christian

2012-10-01

TORPEX is a basic plasma physics toroidal device located at the CRPP-EPFL in Lausanne. In TORPEX, a vertical magnetic field superposed on a toroidal field creates helicoidal field lines with both ends terminating on the torus vessel. We review recent advances in the understanding and control of electrostatic interchange turbulence, associated structures and their effect on suprathermal ions. These advances are obtained using high-resolution diagnostics of plasma parameters and wave fields throughout the whole device cross-section, fluid models and numerical simulations. Furthermore, we discuss future developments including the possibility of generating closed field line configurations with rotational transform using an internal toroidal wire carrying a current. This system will also allow the study of innovative fusion-relevant configurations, such as the snowflake divertor.

High temperature static strain measurement with an electrical resistance strain gage

NASA Technical Reports Server (NTRS)

Lei, Jih-Fen

1992-01-01

An electrical resistance strain gage that can supply accurate static strain measurement for NASP application is being developed both in thin film and fine wire forms. This gage is designed to compensate for temperature effects on substrate materials with a wide range of thermal expansion coefficients. Some experimental results of the wire gage tested on one of the NASP structure materials, i.e., titanium matrix composites, are presented.

Leak testing in parenteral packaging: establishment of direct correlation between helium leak rate measurements and microbial ingress for two different leak types.

PubMed

Morrical, Bradley D; Goverde, Marcel; Grausse, Jean; Gerwig, Tanja; Vorgrimler, Lothar; Morgen, Rachel; Büttiker, Jean-Pierre

2007-01-01

A direct test method using helium leak detection was developed to determine microbial ingress in parenteral vial/rubber closure systems. The purpose of this study was to establish a direct correlation between the helium leak rate and the presence of ingress when vials were submersed under pressure in a broth of bacteria. Results were obtained for two different types of leaks: microholes that have been laser-drilled into thin metal plates, and thin copper wire that was placed between the rubber closure and the glass vial's sealing surface. The results from the microholes showed that the helium leak rate was a function of the square of the hole diameter and fit well with theoretical calculations. The relationship with the wire gave a far more complex dependence and was not modeled theoretically. Comparison with the microbial challenge showed that for microholes a lower size limit was found to be 2 microm with a corresponding leak rate of 1.4 x 10(-3) mbarl/s. For the fine wire experiment the lower limit was 15-microm wire and a corresponding leak rate of 1.3 x 10(-5) mbarl/s. From these tests a safe, lower limit, leak rate was established.

Environmentally sensitive theory of electronic and optical transitions in atomically thin semiconductors

NASA Astrophysics Data System (ADS)

Cho, Yeongsu; Berkelbach, Timothy C.

2018-01-01

We present an electrostatic theory of band-gap renormalization in atomically thin semiconductors that captures the strong sensitivity to the surrounding dielectric environment. In particular, our theory aims to correct known band gaps, such as that of the three-dimensional bulk crystal. Combining our quasiparticle band gaps with an effective-mass theory of excitons yields environmentally sensitive optical gaps as would be observed in absorption or photoluminescence. For an isolated monolayer of MoS2, the presented theory is in good agreement with ab initio results based on the G W approximation and the Bethe-Salpeter equation. We find that changes in the electronic band gap are almost exactly offset by changes in the exciton binding energy such that the energy of the first optical transition is nearly independent of the electrostatic environment, rationalizing experimental observations.

Monitoring the layer-by-layer self-assembly of graphene and graphene oxide by spectroscopic ellipsometry.

PubMed

Zhou, Kai-Ge; Chang, Meng-Jie; Wang, Hang-Xing; Xie, Yu-Long; Zhang, Hao-Li

2012-01-01

Thin films of graphene oxide, graphene and copper (II) phthalocyanine dye have been successfully fabricated by electrostatic layer-by-layer (LbL) assembly approach. We present the first variable angle spectroscopic ellipsometry (VASE) investigation on these graphene-dye hybrid thin films. The thickness evaluation suggested that our LbL assembly process produces highly uniform and reproducible thin films. We demonstrate that the refractive indices of the graphene-dye thin films undergo dramatic variation in the range close to the absorption of the dyes. This investigation provides new insight to the optical properties of graphene containing thin films and shall help to establish an appropriate optical model for graphene-based hybrid materials.

Palladium-chromium static strain gages for high temperatures

NASA Technical Reports Server (NTRS)

Lei, Jih-Fen

1992-01-01

An electrical resistance strain gage that can provide accurate static strain measurement to a temperature of 1500 F or above is being developed both in fine wire and thin film forms. The gage is designed to be temperature compensated on any substrate material. It has a dual element: the gage element is a special alloy, palladium-13wt percent chromium (PdCr), and the compensator element is platinum (Pt). Earlier results of a PdCr based wire gage indicated that the apparent strain of this gage can be minimized and the repeatability of the apparent strain can be improved by prestabilizing the gage on the substrate for a long period of time. However, this kind of prestabilization is not practical in many applications and therefore the development of a wire gage which is prestabilized before installation on the substrate is desirable. This paper will present our recent progress in the development of a prestabilized wire gage which can provide meaningful strain data for the first thermal cycle. A weldable PdCr gage is also being developed for field testing where conventional flame-spraying installation can not be applied. This weldable gage is narrower than a previously reported gage, thereby allowing the gage to be more resistant to buckling under compressive loads. Some preliminary results of a prestabilized wire gage flame-sprayed directly on IN100, an engine material, and a weldable gage spot-welded on IN100 and SCS-6/(beta)21-S Titanium Matrix Composite (TMC), a National Aero-Space Plane (NASP) structure material, will be reported. Progress on the development of a weldable thin film gage will also be addressed. The measurement technique and procedures and the lead wire effect will be discussed.

Simple electronic apparatus for the analysis of radioactively labeled gel electrophoretograms

DOEpatents

Goulianos, Konstantin; Smith, Karen K.; White, Sebastian N.

1982-01-01

A high resolution position sensitive radiation detector for analyzing radiation emanating from a source, constructed of a thin plate having an elongated slot with conductive edges acting as a cathode, a charged anode wire positioned within 0.5 mm adjacent the source and running parallel to the slot and centered therein, an ionizable gas ionized by radiation emanating from the source provided surrounding the anode wire in the slot, a helical wire induction coil serving as a delay line and positioned beneath the anode wire for detecting gas ionization and for producing resulting ionization signals, and processing circuits coupled to the induction coil for receiving ionization signals induced therein after determining therefrom the location along the anode wire of any radiation emanating from the source. An ionization gas of 70% Ar, 29% Isobutane, 0.6% Freon 13BI, and 0.4% Methylal is used.

Structures with negative index of refraction

DOEpatents

Soukoulis, Costas M [Ames, IA; Zhou, Jiangfeng [Ames, IA; Koschny, Thomas [Ames, IA; Zhang, Lei [Ames, IA; Tuttle, Gary [Ames, IA

2011-11-08

The invention provides simplified negative index materials (NIMs) using wire-pair structures, 4-gap single ring split-ring resonator (SRR), fishnet structures and overleaf capacitor SRR. In the wire-pair arrangement, a pair of short parallel wires and continuous wires are used. In the 4-gap single-ring SRR, the SRRs are centered on the faces of a cubic unit cell combined with a continuous wire type resonator. Combining both elements creates a frequency band where the metamaterial is transparent with simultaneously negative .di-elect cons. and .mu.. In the fishnet structure, a metallic mesh on both sides of the dielectric spacer is used. The overleaf capacitor SRR changes the gap capacities to small plate capacitors by making the sections of the SRR ring overlap at the gaps separated by a thin dielectric film. This technique is applicable to conventional SRR gaps but it best deploys for the 4-gap single-ring structures.

Convergence of the Quasi-static Antenna Design Algorithm

DTIC Science & Technology

2013-04-01

was the first antenna design with quasi-static methods. In electrostatics, a perfect conductor is the same as an equipotential surface . A line of...which can cause the equipotential surface to terminate on the disk or feed wire. This requires an additional step in the solution process; the... equipotential surface is sampled to verify that the charge is enclosed by the equipotential surface . The final solution must be verified with a detailed

Single Additive Enables 3D Printing of Highly Loaded Iron Oxide Suspensions.

PubMed

Hodaei, Amin; Akhlaghi, Omid; Khani, Navid; Aytas, Tunahan; Sezer, Dilek; Tatli, Buse; Menceloglu, Yusuf Z; Koc, Bahattin; Akbulut, Ozge

2018-03-21

A single additive, a grafted copolymer, is designed to ensure the stability of suspensions of highly loaded iron oxide nanoparticles (IOPs) and to facilitate three-dimensional (3D) printing of these suspensions in the filament form. This poly (ethylene glycol)-grafted copolymer of N-[3(dimethylamino)propyl]methacrylamide and acrylic acid harnesses both electrostatic and steric repulsion to realize an optimum formulation for 3D printing. When used at 1.15 wt % (by the weight of IOPs), the suspension attains ∼81 wt % solid loading-96% of the theoretical limit as calculated by the Krieger-Dougherty equation. Rectangular, thick-walled toroidal, and thin-walled toroidal magnetic cores and a porous lattice structure are fabricated to demonstrate the utilization of this suspension as an ink for 3D printing. The electrical and magnetic properties of the magnetic cores are characterized through impedance spectroscopy (IS) and vibrating sample magnetometry (VSM), respectively. The IS indicates the possibility of utilizing wire-wound 3D printed cores as the inductive coils. The VSM verifies that the magnetic properties of IOPs before and after the ink formulation are kept almost unchanged because of the low dosage of the additive. This particle-targeted approach for the formulation of 3D printing inks allows embodiment of a fully aqueous system with utmost target material content.

Inward electrostatic precipitation of interplanetary particles

NASA Technical Reports Server (NTRS)

Rulison, Aaron J.; Flagan, Richard C.; Ahrens, Thomas J.

1993-01-01

An inward precipitator collects particles initially dispersed in a gas throughout either a cylindrical or spherical chamber onto a small central planchet. The instrument is effective for particle diameters greater than about 1 micron. One use is the collection of interplanetary dust particles (IDPs) which are stopped in a noble gas (xenon) by drag and ablation after perforating the wall of a thin-walled spacecraft-mounted chamber. First, the particles are positively charged for several seconds by the corona production of positive xenon ions from inward facing needles placed on the chamber wall. Then an electric field causes the particles to migrate toward the center of the instrument and onto the planchet. The collection time (on the order of hours for a 1 m radius spherical chamber) is greatly reduced by the use of optimally located screens which reapportion the electric field. Some of the electric field lines terminate on the wires of the screens so a fraction of the total number of particles in the chamber is lost. The operation of the instrument is demonstrated by experiments which show the migration of carbon soot particles with radius of approximately 1 micron in a 5 cm diameter cylindrical chamber with a single field enhancing screen toward a 3.2 mm central collection rod.

Surface characteristics and damage distributions of diamond wire sawn wafers for silicon solar cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sopori, Bhushan; Devayajanam, Srinivas; Basnyat, Prakash

2016-01-01

This paper describes surface characteristics, in terms of its morphology, roughness and near-surface damage of Si wafers cut by diamond wire sawing (DWS) of Si ingots under different cutting conditions. Diamond wire sawn Si wafers exhibit nearly-periodic surface features of different spatial wavelengths, which correspond to kinematics of various movements during wafering, such as ingot feed, wire reciprocation, and wire snap. The surface damage occurs in the form of frozen-in dislocations, phase changes, and microcracks. The in-depth damage was determined by conventional methods such as TEM, SEM and angle-polishing/defect-etching. However, because these methods only provide local information, we have alsomore » applied a new technique that determines average damage depth over a large area. This technique uses sequential measurement of the minority carrier lifetime after etching thin layers from the surfaces. The lateral spatial damage variations, which seem to be mainly related to wire reciprocation process, were observed by photoluminescence and minority carrier lifetime mapping. Our results show a strong correlation of damage depth on the diamond grit size and wire usage.« less

High-performance, stretchable, wire-shaped supercapacitors.

PubMed

Chen, Tao; Hao, Rui; Peng, Huisheng; Dai, Liming

2015-01-07

A general approach toward extremely stretchable and highly conductive electrodes was developed. The method involves wrapping a continuous carbon nanotube (CNT) thin film around pre-stretched elastic wires, from which high-performance, stretchable wire-shaped supercapacitors were fabricated. The supercapacitors were made by twisting two such CNT-wrapped elastic wires, pre-coated with poly(vinyl alcohol)/H3PO4 hydrogel, as the electrolyte and separator. The resultant wire-shaped supercapacitors exhibited an extremely high elasticity of up to 350% strain with a high device capacitance up to 30.7 F g(-1), which is two times that of the state-of-the-art stretchable supercapacitor under only 100% strain. The wire-shaped structure facilitated the integration of multiple supercapacitors into a single wire device to meet specific energy and power needs for various potential applications. These supercapacitors can be repeatedly stretched from 0 to 200% strain for hundreds of cycles with no change in performance, thus outperforming all the reported state-of-the-art stretchable electronics. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Numerical simulations for quantitative analysis of electrostatic interaction between atomic force microscopy probe and an embedded electrode within a thin dielectric: meshing optimization, sensitivity to potential distribution and impact of cantilever contribution

NASA Astrophysics Data System (ADS)

Azib, M.; Baudoin, F.; Binaud, N.; Villeneuve-Faure, C.; Bugarin, F.; Segonds, S.; Teyssedre, G.

2018-04-01

Recent experimental results demonstrated that an electrostatic force distance curve (EFDC) can be used for space charge probing in thin dielectric layers. A main advantage of the method is claimed to be its sensitivity to charge localization, which, however, needs to be substantiated by numerical simulations. In this paper, we have developed a model which permits us to compute an EFDC accurately by using the most sophisticated and accurate geometry for the atomic force microscopy probe. To avoid simplifications and in order to reproduce experimental conditions, the EFDC has been simulated for a system constituted of a polarized electrode embedded in a thin dielectric layer (SiN x ). The individual contributions of forces on the tip and on the cantilever have been analyzed separately to account for possible artefacts. The EFDC sensitivity to potential distribution is studied through the change in electrode shape, namely the width and the depth. Finally, the numerical results have been compared with experimental data.

Effects of BOX engineering on analogue/RF and circuit performance of InGaAs-OI-Si MOSFET

NASA Astrophysics Data System (ADS)

Maity, Subir Kr.; Pandit, Soumya

2017-11-01

InGaAs is an attractive choice as alternate channel material in n-channel metal oxide semiconductor transistor for high-performance applications. However, electrostatic integrity of such device is poor. In this paper, we present a comprehensive technology computer-aided design simulation-based study of the effect of scaling the thickness of the buried oxide (BOX) region and varying the dielectric constant of BOX material on the electrostatic integrity, analogue/radio frequency (RF) performance and circuit performance of InGaAs-on-Insulator device. Device with thin BOX layer gives better drain-induced barrier lowering performance which enhances output resistance. The carrier mobility remains almost constant with thinning of BOX layer up to certain value. By lowering the dielectric constant of the BOX material, it is further possible to improve the analogue and RF performance. Effect of BOX thickness scaling and role of BOX dielectric material on gain-frequency response of common source amplifier is also studied. It is observed that frequency response of the amplifier improves for thin BOX and with low dielectric constant-based material.

Laser Radiation Pressure Acceleration of Monoenergetic Protons in an Ultra-Thin Foil

NASA Astrophysics Data System (ADS)

Eliasson, Bengt; Liu, Chuan S.; Shao, Xi; Sagdeev, Roald Z.; Shukla, Padma K.

2009-11-01

We present theoretical and numerical studies of the acceleration of monoenergetic protons in a double layer formed by the laser irradiation of an ultra-thin film. The stability of the foil is investigated by direct Vlasov-Maxwell simulations for different sets of laser-plasma parameters. It is found that the foil is stable, due to the trapping of both electrons and ions in the thin laser-plasma interaction region, where the electrons are trapped in a potential well composed of the ponderomo-tive potential of the laser light and the electrostatic potential due to the ions, and the ions are trapped in a potential well composed of the inertial potential in an accelerated frame and the electrostatic potential due to the electrons. The result is a stable double layer, where the trapped ions are accelerated to monoenergetic energies up to 100 MeV and beyond, which makes them suitable for medical applications cancer treatment. The underlying physics of trapped and untapped ions in a double layer is also investigated theoretically and numerically.

An ionic-chemical-mechanical model for muscle contraction.

PubMed

Manning, Gerald S

2016-12-01

The dynamic process underlying muscle contraction is the parallel sliding of thin actin filaments along an immobile thick myosin fiber powered by oar-like movements of protruding myosin cross bridges (myosin heads). The free energy for functioning of the myosin nanomotor comes from the hydrolysis of ATP bound to the myosin heads. The unit step of translational movement is based on a mechanical-chemical cycle involving ATP binding to myosin, hydrolysis of the bound ATP with ultimate release of the hydrolysis products, stress-generating conformational changes in the myosin cross bridge, and relief of built-up stress in the myosin power stroke. The cycle is regulated by a transition between weak and strong actin-myosin binding affinities. The dissociation of the weakly bound complex by addition of salt indicates the electrostatic basis for the weak affinity, while structural studies demonstrate that electrostatic interactions among negatively charged amino acid residues of actin and positively charged residues of myosin are involved in the strong binding interface. We therefore conjecture that intermediate states of increasing actin-myosin engagement during the weak-to-strong binding transition also involve electrostatic interactions. Methods of polymer solution physics have shown that the thin actin filament can be regarded in some of its aspects as a net negatively charged polyelectrolyte. Here we employ polyelectrolyte theory to suggest how actin-myosin electrostatic interactions might be of significance in the intermediate stages of binding, ensuring an engaged power stroke of the myosin motor that transmits force to the actin filament, and preventing the motor from getting stuck in a metastable pre-power stroke state. We provide electrostatic force estimates that are in the pN range known to operate in the cycle. © 2016 Wiley Periodicals, Inc.

Electrostatic and aerodynamic forced vibrations of a thin flexible electrode: Quasi-periodic vs. chaotic oscillations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Madanu, Sushma B.; Barbel, Stanley I.; Ward, Thomas

In this paper, transverse vibrations of an electrostatically actuated thin flexible cantilever perturbed by low-speed air flow are studied using both experiments and numerical modeling. In the experiments, the dynamic characteristics of the cantilever are studied by supplying a DC voltage with an AC component for electrostatic forcing and a constant uniform air flow around the cantilever system for aerodynamic forcing. A range of control parameters leading to stable vibrations are established using a dimensionless operating parameter that is the ratio of the induced and the free stream velocities. Numerical results are validated with experimental data. Assuming the amplitude ofmore » vibrations are small, then a non-linear dynamic Euler-Bernoulli beam equation with viscous damping and gravitational effects is used to model the equation of motion. Aerodynamic forcing is modelled as a temporally sinusoidal and uniform force acting perpendicular to the beam length. The forcing amplitude is found to be proportional to the square of the air flow velocity. Numerical results strongly agree with the experiments predicting accurate vibration amplitude, displacement frequency, and quasi-periodic displacement of the cantilever tip.« less

Monitoring electrostatically-induced deflection, strain and doping in suspended graphene using Raman spectroscopy

NASA Astrophysics Data System (ADS)

Metten, Dominik; Froehlicher, Guillaume; Berciaud, Stéphane

2017-03-01

Electrostatic gating offers elegant ways to simultaneously strain and dope atomically thin membranes. Here, we report on a detailed in situ Raman scattering study on graphene, suspended over a Si/SiO2 substrate. In such a layered structure, the intensity of the Raman G- and 2D-mode features of graphene are strongly modulated by optical interference effects and allow an accurate determination of the electrostatically-induced membrane deflection, up to irreversible collapse. The membrane deflection is successfully described by an electromechanical model, which we also use to provide useful guidelines for device engineering. In addition, electrostatically-induced tensile strain is determined by examining the softening of the Raman features. Due to a small residual charge inhomogeneity, we find that non-adiabatic anomalous phonon softening is negligible compared to strain-induced phonon softening. These results open perspectives for innovative Raman scattering-based readout schemes in two-dimensional nanoresonators.

Adaptive composites with embedded NiTiCu wires

NASA Astrophysics Data System (ADS)

Balta-Neumann, J. Antonio; Michaud, Veronique J.; Parlinska, Magdelena; Gotthardt, Rolf; Manson, Jan-Anders E.

2001-07-01

Adaptive composites have been produced by embedding prestrained shape memory alloy (SMA) wires into an epoxy matrix, reinforced with aramid fibers. These materials demonstrate attractive effects such as shape change or a shift in the vibration frequency upon activation. When heated above their transformation temperature, the wires' strain recovery is confined, and recovery stresses are generated. As a result, if the wires are placed along the neutral axis of a composite beam, a shift in resonance vibration frequency can be observed. To optimize the design of such composites, the matrix - SMA wire interfacial shear strength has been analyzed with the pull out testing technique. It is shown that the nature of the wire surface influences the interfacial shear strength, and that satisfactory results are obtained for SMA wires with a thin oxide layer. Composite samples consisting of two different types of pre- strained NiTiCu wires embedded in either pure epoxy matrix or Kevlar-epoxy matrix were produced. The recovery force and vibration response of composites were measured in a clamped-clamped configuration, to assess the effect of wire type and volume fraction. The results are highly reproducible in all cases with a narrow hysteresis loop, which makes NiTiCu wires good candidates for adaptive composites. The recovery forces increase with the volume fraction of the embedded wires, are higher when the wires are embedded in a low CTE matrix and, at a given temperature, are higher when the wire transformation temperature is lower.

Synthesis of Au microwires by selective oxidation of Au–W thin-film composition spreads

PubMed Central

Hamann, Sven; Brunken, Hayo; Salomon, Steffen; Meyer, Robert; Savan, Alan; Ludwig, Alfred

2013-01-01

We report on the stress-induced growth of Au microwires out of a surrounding Au–W matrix by selective oxidation, in view of a possible application as ‘micro-Velcro’. The Au wires are extruded due to the high compressive stress in the tungsten oxide formed by oxidation of elemental W. The samples were fabricated as a thin-film materials library using combinatorial sputter deposition followed by thermal oxidation. Sizes and shapes of the Au microwires were investigated as a function of the W to Au ratio. The coherence length and stress state of the Au microwires were related to their shape and plastic deformation. Depending on the composition of the Au–W precursor, the oxidized samples showed regions with differently shaped Au microwires. The Au48W52 composition yielded wires with the maximum length to diameter ratio due to the high compressive stress in the tungsten oxide matrix. The values of wire length (35 μm) and diameter (2 μm) achieved at the Au48W52 composition are suitable for micro-Velcro applications. PMID:27877561

The USML-1 wire insulation flammability glovebox experiment

NASA Technical Reports Server (NTRS)

Greenberg, Paul S.; Sacksteder, Kurt R.; Kashiwagi, Takashi

1995-01-01

Flame spreading tests have been conducted using thin fuels in microgravity where buoyant convection is suppressed. In spacecraft experiments flames were ignited in quiescent atmospheres with an elevated oxygen content, demonstrating that diffusional mechanisms can be sufficient alone to sustain flame spreading. In ground-based facilities (i.e. drop towers and parabolic aircraft) low-speed convection sustains flames at much lower concentrations of atmospheric oxygen than in quiescent microgravity. Ground-based experiments are limited to very thin fuels (e.g., tissue paper); practical fuels, which are thicker, require more test time than is available. The Glovebox Facility provided for the USML 1 mission provided an opportunity to obtain flame spreading data for thicker fuel Herein we report the results from the Wire Insulation Flammability (WIF) Experiment performed in the Glovebox Facility. This experiment explored the heating, ignition and burning of 0.65 mm thick polyethylene wire insulation in low-speed flows in a reduced gravity environment. Four tests were conducted, two each in concurrent flow (WIF A and C) and opposed flow (WIF B and D), providing the first demonstration of flame spreading in controlled forced convection conducted in space.

A tension-torsional fatigue testing apparatus for micro-scale components.

PubMed

Fu, Sichao; Wang, Lei; Chen, Gang; Yu, Dunji; Chen, Xu

2016-01-01

Mechanical characterization of micro-scale components under complex loading conditions is a great challenge. To meet such a challenge, a microtension-torsional fatigue testing apparatus is developed in this study that specializes in the evaluation of multiaxial fatigue behavior of thin stent wires. The actuation and measurement in two controlled directions are incorporated in the tensile and torsional load frames, respectively, and a thrust air bearing is applied for the coupling of the two frames. The axial deformation of specimens measured by a grating sensor built in the linear motor and by a non-contact displacement detect system is compared and corrected. The accuracy of the torque measurement is proved by torsion tests on thin wires of 316L stainless steel in nominal diameters of 100 μm. Multistep torsion test, multiaxial ratcheting test, and a fully strain controlled multiaxial cyclic test are performed on 100 μm and 200 μm-diameter 316L wires using this apparatus. The capability of the equipment in tension-torsional cyclic tests for micro-scale specimens is demonstrated by the experimental results.

A tension-torsional fatigue testing apparatus for micro-scale components

NASA Astrophysics Data System (ADS)

Fu, Sichao; Wang, Lei; Chen, Gang; Yu, Dunji; Chen, Xu

2016-01-01

Mechanical characterization of micro-scale components under complex loading conditions is a great challenge. To meet such a challenge, a microtension-torsional fatigue testing apparatus is developed in this study that specializes in the evaluation of multiaxial fatigue behavior of thin stent wires. The actuation and measurement in two controlled directions are incorporated in the tensile and torsional load frames, respectively, and a thrust air bearing is applied for the coupling of the two frames. The axial deformation of specimens measured by a grating sensor built in the linear motor and by a non-contact displacement detect system is compared and corrected. The accuracy of the torque measurement is proved by torsion tests on thin wires of 316L stainless steel in nominal diameters of 100 μm. Multistep torsion test, multiaxial ratcheting test, and a fully strain controlled multiaxial cyclic test are performed on 100 μm and 200 μm-diameter 316L wires using this apparatus. The capability of the equipment in tension-torsional cyclic tests for micro-scale specimens is demonstrated by the experimental results.

Miniature hybrid microwave IC's using a novel thin-film technology

NASA Astrophysics Data System (ADS)

Eda, Kazuo; Miwa, Tetsuji; Taguchi, Yutaka; Uwano, Tomoki

1990-12-01

A novel thin-film technology for miniature hybrid microwave ICs is presented. All passive components, such as resistors and capacitors, are fully integrated on ordinary alumina ceramic substrates using the thin-film technology with very high yield. The numbers of parts and wiring processes were significantly reduced. This technology was applied to the fabrication of Ku-band solid-state power amplifiers. This thin-film technology offers the following advantages: (1) a very high yield fabrication process of thin-film capacitor having excellent electrical characteristics in the gigahertz range (Q = 230 at 12 GHz) and reliability: (2) two kinds of thin-film resistors having different temperature coefficients of resistivity and a lift-off process to integrate them with thin-film capacitors; and (3) a matching method using the thin-film capacitor.

Electronic measurements in an alternating magnetic field (AMF) for studying magnetic nanoparticle hyperthermia

NASA Astrophysics Data System (ADS)

Boekelheide, Z.; Hussein, Z. A.; Hartzell, S.

Magnetic nanoparticle hyperthermia is a promising cancer treatment in which magnetic nanoparticles are injected into a tumor and then exposed to an alternating magnetic field (AMF). This process releases heat and damages tumor cells, but the exact mechanisms behind the effectiveness of this therapy are still unclear. Accurate sensors are required to monitor the temperature and, potentially, other parameters such as magnetic field or mechanical stress during clinical therapy or lab research. Often, optical rather than electronic temperature sensors are used to avoid eddy current self-heating in conducting parts in the AMF. However, eddy current heating is strongly dependent on the size and geometry of the conducting part, thus micro- and nano-scale electronics are a promising possibility for further exploration into magnetic nanoparticle hyperthermia. This presentation quantitatively discusses the eddy current self-heating of thin wires (thermocouples) and will also present a proof of concept thin film resistive thermometer and magnetic field sensor along with measurements of their eddy current self-heating. The results show that electronic measurements are feasible in an AMF with both thin wires and patterned thin film sensors under certain conditions.

Diminish electrostatic in piezoresponse force microscopy through longer or ultra-stiff tips

NASA Astrophysics Data System (ADS)

Gomez, A.; Puig, T.; Obradors, X.

2018-05-01

Piezoresponse Force Microscopy is a powerful but delicate nanoscale technique that measures the electromechanical response resulting from the application of a highly localized electric field. Though mechanical response is normally due to piezoelectricity, other physical phenomena, especially electrostatic interaction, can contribute to the signal read. We address this problematic through the use of longer ultra-stiff probes providing state of the art sensitivity, with the lowest electrostatic interaction and avoiding working in high frequency regime. In order to find this solution we develop a theoretical description addressing the effects of electrostatic contributions in the total cantilever vibration and its quantification for different setups. The theory is subsequently tested in a Periodically Poled Lithium Niobate (PPLN) crystal, a sample with well-defined 0° and 180° domains, using different commercial available conductive tips. We employ the theoretical description to compare the electrostatic contribution effects into the total phase recorded. Through experimental data our description is corroborated for each of the tested commercially available probes. We propose that a larger probe length can be a solution to avoid electrostatic forces, so the cantilever-sample electrostatic interaction is reduced. Our proposed solution has great implications into avoiding artifacts while studying soft biological samples, multiferroic oxides, and thin film ferroelectric materials.

A High-Sensitivity Current Sensor Utilizing CrNi Wire and Microfiber Coils

PubMed Central

Xie, Xiaodong; Li, Jie; Sun, Li-Peng; Shen, Xiang; Jin, Long; Guan, Bai-ou

2014-01-01

We obtain an extremely high current sensitivity by wrapping a section of microfiber on a thin-diameter chromium-nickel wire. Our detected current sensitivity is as high as 220.65 nm/A2 for a structure length of only 35 μm. Such sensitivity is two orders of magnitude higher than the counterparts reported in the literature. Analysis shows that a higher resistivity or/and a thinner diameter of the metal wire may produce higher sensitivity. The effects of varying the structure parameters on sensitivity are discussed. The presented structure has potential for low-current sensing or highly electrically-tunable filtering applications. PMID:24824372

A high-sensitivity current sensor utilizing CrNi wire and microfiber coils.

PubMed

Xie, Xiaodong; Li, Jie; Sun, Li-Peng; Shen, Xiang; Jin, Long; Guan, Bai-ou

2014-05-12

We obtain an extremely high current sensitivity by wrapping a section of microfiber on a thin-diameter chromium-nickel wire. Our detected current sensitivity is as high as 220.65 nm/A2 for a structure length of only 35 μm. Such sensitivity is two orders of magnitude higher than the counterparts reported in the literature. Analysis shows that a higher resistivity or/and a thinner diameter of the metal wire may produce higher sensitivity. The effects of varying the structure parameters on sensitivity are discussed. The presented structure has potential for low-current sensing or highly electrically-tunable filtering applications.

Quantized conductance observed during sintering of silver nanoparticles by intense terahertz pulses

NASA Astrophysics Data System (ADS)

Takano, Keisuke; Harada, Hirofumi; Yoshimura, Masashi; Nakajima, Makoto

2018-04-01

We show that silver nanoparticles, which are deposited on a terahertz-receiving antenna, can be sintered by intense terahertz pulse irradiation. The conductance of the silver nanoparticles between the antenna electrodes is measured under the terahertz pulse irradiation. The dispersant materials surrounding the nanoparticles are peeled off, and conduction paths are created. We reveal that, during sintering, quantum point contacts are formed, leading to quantized conductance between the electrodes with the conductance quantum, which reflects the formation of atomically thin wires. The terahertz electric pulses are sufficiently intense to activate electromigration, i.e., transfer of kinetic energy from the electrons to the silver atoms. The silver atoms move and atomically thin wires form under the intense terahertz pulse irradiation. These findings may inspire nanoscale structural processing by terahertz pulse irradiation.

Notched K-wire for low thermal damage bone drilling.

PubMed

Liu, Yao; Belmont, Barry; Wang, Yiwen; Tai, Bruce; Holmes, James; Shih, Albert

2017-07-01

The Kirschner wire (K-wire) is a common bone drilling tool in orthopedic surgery to affix fractured bone. Significant heat is produced due to both the cutting and the friction between the K-wire and the bone debris during drilling. Such heat can result in high temperatures, leading to osteonecrosis and other secondary injuries. To reduce thermal injury and other high-temperature associated complications, a new K-wire design with three notches along the three-plane trocar tip fabricated using a thin micro-saw tool is studied. These notches evacuate bone debris and reduce the clogging and heat generation during bone drilling. A set of four K-wires, one without notches and three notched, with depths of 0.5, 0.75, and 1mm, are evaluated. Bone drilling experiments conducted on bovine cortical bone show that notched K-wires could effectively decrease the temperature, thrust force, and torque during bone drilling. K-wires with notches 1mm deep reduced the thrust force and torque by approximately 30%, reduced peak temperatures by 43%, and eliminated blackened burn marks in bone. This study demonstrates that a simple modification of the tip of K-wires can effectively reduce bone temperatures during drilling. Copyright © 2017 IPEM. Published by Elsevier Ltd. All rights reserved.

Bruce Wiegman with a tether for the Electostatic Propulsion System.

NASA Image and Video Library

2015-09-30

BRUCE WIEGMANN, AN ENGINEER AT NASA'S MARSHALL SPACE FLIGHT CENTER IN HUNTSVILLE, ALABAMA, EXAMINES A HAIR-THIN TETHER THAT WILL BE PART OF AN ELECTROSTATIC PROPULSION SYSTEM THAT COULD SEND SPACECRAFT ON INTERSTELLAR MISSIONS.

High efficiency ion beam accelerator system

NASA Technical Reports Server (NTRS)

Aston, G.

1981-01-01

An ion accelerator system that successfully combines geometrical and electrostatic focusing principles is presented. This accelerator system uses thin, concave, multiple-hole, closely spaced graphite screen and focusing grids which are coupled to single slot accelerator and decelerator grids to provide high ion extraction efficiency and good focusing. Tests with the system showed a substantial improvement in ion beam current density and collimation as compared with a Pierce electrode configuration. Durability of the thin graphite screen and focusing grids has been proven, and tests are being performed to determine the minimum screen and focusing grid spacing and thickness required to extract the maximum reliable beam current density. Compared with present neutral beam injector accelerator systems, this one has more efficient ion extraction, easier grid alignment, easier fabrication, a less cumbersome design, and the capacity to be constructed in a modular fashion. Conceptual neutral beam injector designs using this modular approach have electrostatic beam deflection plates downstream of each module.

A three dimensional dynamic study of electrostatic charging in materials

NASA Technical Reports Server (NTRS)

Katz, I.; Parks, D. E.; Mandell, M. J.; Harvey, J. M.; Brownell, D. H., Jr.; Wang, S. S.; Rotenberg, M.

1977-01-01

A description is given of the physical models employed in the NASCAP (NASA Charging Analyzer Program) code, and several test cases are presented. NASCAP dynamically simulates the charging of an object made of conducting segments which may be entirely or partially covered with thin dielectric films. The object may be subject to either ground test or space user-specified environments. The simulation alternately treats (1) the tendency of materials to accumulate and emit charge when subject to plasma environment, and (2) the consequent response of the charged particle environment to an object's electrostatic field. Parameterized formulations of the emission properties of materials subject to bombardment by electrons, protons, and sunlight are presented. Values of the parameters are suggested for clean aluminum, Al2O3, clean magnesium, MgO, SiO2 kapton, and teflon. A discussion of conductivity in thin dielectrics subject to radiation and high fields is given, together with a sample calculation.

Using the Cycloid as an Introduction to Transformations of E and B Fields

NASA Astrophysics Data System (ADS)

Frodyma, Marc; Le, My Phuong

2018-05-01

The transformations of electric and magnetic fields are usually introduced by viewing systems such as a long, straight current-carrying wire and a parallel plate capacitor in two different reference frames. These well-known examples show that magnetism is a necessary consequence of augmenting electrostatics with relativity. Because they require the full apparatus of Lorentz contraction and Lorentz transformation of forces, they are often postponed until the upper-division undergraduate electrodynamics course.

Thin film solar cells with Si nanocrystallites embedded in amorphous intrinsic layers by hot-wire chemical vapor deposition.

PubMed

Park, Seungil; Parida, Bhaskar; Kim, Keunjoo

2013-05-01

We investigated the thin film growths of hydrogenated silicon by hot-wire chemical vapor deposition with different flow rates of SiH4 and H2 mixture ambient and fabricated thin film solar cells by implementing the intrinsic layers to SiC/Si heterojunction p-i-n structures. The film samples showed the different infrared absorption spectra of 2,000 and 2,100 cm(-1), which are corresponding to the chemical bonds of SiH and SiH2, respectively. The a-Si:H sample with the relatively high silane concentration provides the absorption peak of SiH bond, but the microc-Si:H sample with the relatively low silane concentration provides the absorption peak of SiH2 bond as well as SiH bond. Furthermore, the microc-Si:H sample showed the Raman spectral shift of 520 cm(-1) for crystalline phase Si bonds as well as the 480 cm(-1) for the amorphous phase Si bonds. These bonding structures are very consistent with the further analysis of the long-wavelength photoconduction tail and the formation of nanocrystalline Si structures. The microc-Si:H thin film solar cell has the photovoltaic behavior of open circuit voltage similar to crystalline silicon thin film solar cell, indicating that microc-Si:H thin film with the mixed phase of amorphous and nanocrystalline structures show the carrier transportation through the channel of nanocrystallites.

The impact of electrostatic correlations on Dielectrophoresis of Non-conducting Particles

NASA Astrophysics Data System (ADS)

Alidoosti, Elaheh; Zhao, Hui

2017-11-01

The dipole moment of a charged, dielectric, spherical particle under the influence of a uniform alternating electric field is computed theoretically and numerically by solving the modified continuum Poisson-Nernst-Planck (PNP) equations accounting for ion-ion electrostatic correlations that is important at concentrated electrolytes (Phys. Rev. Lett. 106, 2011). The dependence on the frequency, zeta potential, electrostatic correlation lengths, and double layer thickness is thoroughly investigated. In the limit of thin double layers, we carry out asymptotic analysis to develop simple models which are in good agreement with the modified PNP model. Our results suggest that the electrostatic correlations have a complicated impact on the dipole moment. As the electrostatic correlations length increases, the dipole moment decreases, initially, reach a minimum, and then increases since the surface conduction first decreases and then increases due to the ion-ion correlations. The modified PNP model can improve the theoretical predictions particularly at low frequencies where the simple model can't qualitatively predict the dipole moment. This work was supported, in part, by NIH R15GM116039.

Probing spin helical surface states in topological HgTe nanowires

NASA Astrophysics Data System (ADS)

Ziegler, J.; Kozlovsky, R.; Gorini, C.; Liu, M.-H.; Weishäupl, S.; Maier, H.; Fischer, R.; Kozlov, D. A.; Kvon, Z. D.; Mikhailov, N.; Dvoretsky, S. A.; Richter, K.; Weiss, D.

2018-01-01

Nanowires with helical surface states represent key prerequisites for observing and exploiting phase-coherent topological conductance phenomena, such as spin-momentum locked quantum transport or topological superconductivity. We demonstrate in a joint experimental and theoretical study that gated nanowires fabricated from high-mobility strained HgTe, known as a bulk topological insulator, indeed preserve the topological nature of the surface states, that moreover extend phase-coherently across the entire wire geometry. The phase-coherence lengths are enhanced up to 5 μ m when tuning the wires into the bulk gap, so as to single out topological transport. The nanowires exhibit distinct conductance oscillations, both as a function of the flux due to an axial magnetic field and of a gate voltage. The observed h /e -periodic Aharonov-Bohm-type modulations indicate surface-mediated quasiballistic transport. Furthermore, an in-depth analysis of the scaling of the observed gate-dependent conductance oscillations reveals the topological nature of these surface states. To this end we combined numerical tight-binding calculations of the quantum magnetoconductance with simulations of the electrostatics, accounting for the gate-induced inhomogeneous charge carrier densities around the wires. We find that helical transport prevails even for strongly inhomogeneous gating and is governed by flux-sensitive high-angular momentum surface states that extend around the entire wire circumference.

Proton acceleration to above 5.5 MeV by interaction of 1017 W/cm2 laser pulse with H2O nano-wire targets

NASA Astrophysics Data System (ADS)

Schleifer, E.; Bruner, N.; Eisenmann, S.; Botton, M.; Pikuz, S. A., Jr.; Faenov, A. Y.; Gordon, D.; Zigler, A.

2011-05-01

Compact sources of high energy protons (50-500MeV) are expected to be key technology in a wide range of scientific applications 1-8. Particularly promising is the target normal sheah acceleration (TNSA) scheme 9,10, holding record level of 67MeV protons generated by a peta-Watt laser 11. In general, laser intensity exceeding 1018 W/cm2 is required to produce MeV level protons. Enhancing the energy of generated protons using compact laser sources is very attractive task nowadays. Recently, nano-scale targets were used to accelerate ions 12,13. Here we report on the first generation of 5.5-7.5MeV protons by modest laser intensities (4.5 × 1017 W/cm2) interacting with H2O nano-wires (snow) deposited on a Sapphire substrate. In this setup, the plasma near the tip of the nano-wire is subject to locally enhanced laser intensity with high spatial gradients, and confined charge separation is obtained. Electrostatic fields of extremely high intensities are produced, and protons are accelerated to MeV-level energies. Nano-wire engineered targets will relax the demand of peak energy from laser based sources.

A novel multi-actuation CMOS RF MEMS switch

NASA Astrophysics Data System (ADS)

Lee, Chiung-I.; Ko, Chih-Hsiang; Huang, Tsun-Che

2008-12-01

This paper demonstrates a capacitive shunt type RF MEMS switch, which is actuated by electro-thermal actuator and electrostatic actuator at the same time, and than latching the switching status by electrostatic force only. Since thermal actuators need relative low voltage compare to electrostatic actuators, and electrostatic force needs almost no power to maintain the switching status, the benefits of the mechanism are very low actuation voltage and low power consumption. Moreover, the RF MEMS switch has considered issues for integrated circuit compatible in design phase. So the switch is fabricated by a standard 0.35um 2P4M CMOS process and uses wet etching and dry etching technologies for postprocess. This compatible ability is important because the RF characteristics are not only related to the device itself. If a packaged RF switch and a packaged IC wired together, the parasitic capacitance will cause the problem for optimization. The structure of the switch consists of a set of CPW transmission lines and a suspended membrane. The CPW lines and the membrane are in metal layers of CMOS process. Besides, the electro-thermal actuators are designed by polysilicon layer of the CMOS process. So the RF switch is only CMOS process layers needed for both electro-thermal and electrostatic actuations in switch. The thermal actuator is composed of a three-dimensional membrane and two heaters. The membrane is a stacked step structure including two metal layers in CMOS process, and heat is generated by poly silicon resistors near the anchors of membrane. Measured results show that the actuation voltage of the switch is under 7V for electro-thermal added electrostatic actuation.

Thin Metallic Films From Solvated Metal Atoms

NASA Astrophysics Data System (ADS)

Trivino, Galo C.; Klabunde, Kenneth J.; Dale, Brock

1988-02-01

Metals were evaporated under vacuum and the metal atoms solvated by excess organic solvents at low temperature. Upon warming stable colloidal metal particles were formed by controlled metal atom clustering. The particles were stabilized toward flocculation by solvation and electrostatic effects. Upon solvent removal the colloidal particles grew to form thin films that were metallic in appearance, but showed higher resistivities than pure metallic films. Gold, palladium, platinium, and especially indium are discussed.

Bistability in Doped Organic Thin Film Transistors (Preprint)

DTIC Science & Technology

2007-03-01

small molecules (e.g. pentacene ). As such, they do not necessarily compete with these more typical organic transistors, but rather have pertinence...involves dipping a substrate between two dilute polyelectrolyte solutions of opposite charge to build up a thin film via the electrostatic interactions...recovery is due to trapped O2(g) remaining in the film, which causes the reverse of reaction (1) to occur and the concomitant increase in the level of

MASS SPECTROMETER

DOEpatents

White, F.A.

1960-08-23

A mass spectrometer is designed with a first adjustable magnetic field for resolving an ion beam into beams of selected masses, a second adjustable magnetic field for further resolving the ion beam from the first field into beams of selected masses, a thin foil disposed in the path of the beam between the first and second magnets to dissociate molecular ions incident thereon, an electrostatic field for further resolving the ion beam from the second field into beams of selected masses, and a detector disposed adjacent to the electrostatic field to receive the ion beam.

Laser Annealing on the Surface Treatment of Thin Super Elastic NiTi Wire

NASA Astrophysics Data System (ADS)

Samal, S.; Heller, L.; Brajer, J.; Tyc, O.; Kadrevek, L.; Sittner, P.

2018-05-01

Here the aim of this research is annealing the surface of NiTi wire for shape memory alloy, super-elastic wire by solid state laser beam. The laser surface treatment was carried out on the NiTi wire locally with fast, selective, surface heat treatment that enables precisely tune the localized material properties without any precipitation. Both as drawn (hard) and straight annealing NiTi wire were considered for laser annealing with input power 3 W, with precisely focusing the laser beam height 14.3 % of the Z-axis with a spot size of 1 mm. However, straight annealing wire is more interest due to its low temperature shape setting behavior and used by companies for stent materials. The variable parameter such as speed of the laser scanning and tensile stress on the NiTi wire were optimized to observe the effect of laser response on the sample. Superelastic, straight annealed NiTi wires (d: 0.10 mm) were held prestrained at the end of the superelastic plateau (ε: 5 ∼6.5 %) above the superelastic region by a tensile machine ( Mitter: miniature testing rig) at room temperature (RT). Simultaneously, the hardness of the wires along the cross-section was performed by nano-indentation (NI) method. The hardness of the NiTi wire corresponds to phase changes were correlated with NI test. The laser induced NiTi wire shows better fatigue performance with improved 6500 cycles.

High precision electric gate for time-of-flight ion mass spectrometers

NASA Technical Reports Server (NTRS)

Sittler, Edward C. (Inventor)

2011-01-01

A time-of-flight mass spectrometer having a chamber with electrodes to generate an electric field in the chamber and electric gating for allowing ions with a predetermined mass and velocity into the electric field. The design uses a row of very thin parallel aligned wires that are pulsed in sequence so the ion can pass through the gap of two parallel plates, which are biased to prevent passage of the ion. This design by itself can provide a high mass resolution capability and a very precise start pulse for an ion mass spectrometer. Furthermore, the ion will only pass through the chamber if it is within a wire diameter of the first wire when it is pulsed and has the right speed so it is near all other wires when they are pulsed.

Measurement and Modeling of Dispersive Pulse Propagation in Drawn Wire Waveguides

NASA Technical Reports Server (NTRS)

Madaras, Eric I.; Kohl, Thomas W.; Rogers, Wayne P.

1995-01-01

An analytical model of dispersive pulse propagation in semi-infinite cylinders due to transient axially symmetric end conditions has been experimentally investigated. Specifically, the dispersive propagation of the first axially symmetric longitudinal mode in thin wire waveguides, which have ends in butt contact with longitudinal piezoelectric ultrasonic transducers, is examined. The method allows for prediction of a propagated waveform given a measured source waveform, together with the material properties of the cylinder. Alternatively, the source waveform can be extracted from measurement of the propagated waveform. The material properties required for implementation of the pulse propagation model are determined using guided wave phase velocity measurements. Hard tempered aluminum 1100 and 304 stainless steel wires, with 127, 305, and 406 micron diam., were examined. In general, the drawn wires were found to behave as transversely isotropic media.

Measurement and modeling of dispersive pulse propagation in draw wire waveguides

NASA Technical Reports Server (NTRS)

Madaras, Eric I.; Kohl, Thomas W.; Rogers, Wayne P.

1995-01-01

An analytical model of dispersive pulse propagation in semi-infinite cylinders due to transient axially symmetric end conditions has been experimentally investigated. Specifically, the dispersive propagation of the first axially symmetric longitudinal mode in thin wire waveguides, which have ends in butt contact with longitudinal piezoelectric ultrasonic transducers, is examined. The method allows for prediction of a propagated waveform given a measured source waveform, together with the material properties of the cylinder. Alternatively, the source waveform can be extracted from measurement of the propagated waveform. The material properties required for implementation of the pulse propagation model are determined using guided wave phase velocity measurements. Hard tempered aluminum 1100 and 304 stainless steel wires, with 127, 305, and 406 micron diam., were examined. In general, the drawn wires were found to behave as transversely isotropic media.

A nanofabricated wirescanner with free standing wires: Design, fabrication and experimental results

NASA Astrophysics Data System (ADS)

Veronese, M.; Grulja, S.; Penco, G.; Ferianis, M.; Fröhlich, L.; Dal Zilio, S.; Greco, S.; Lazzarino, M.

2018-05-01

Measuring the transverse size of electron beams is of crucial importance in modern accelerators, from large colliders to free electron lasers to storage rings. For this reason several kind of beam instrumentation have been developed such as optical transition radiation screens, scintillating screens, laser scanners and wire scanners. The last ones although providing only a multishot profile in one plane have demonstrated a very high resolution. Wirescanners employ thin wires with typical thickness of the order of tens of microns that are scanned across the beam, whilst ionizing radiation generated from the impact of the electrons with the wires is detected. In this paper we describe a new approach to wirescanners design based on nanofabrication technologies opening new possibilities in term of wire shape, size, material and thickness with potential for sub-micron resolution and increase flexibility for instrumentation designers. We present a device fitted with nanofabricated wires and its fabrication process. We also report the measurements performed on the FERMI FEL electron beam with the goal of providing an online profile measurement without perturbing the FEL.

Transport of energy by ultraintense laser-generated electrons in nail-wire targets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ma, T.; Lawrence Livermore National Laboratory, Livermore, California 94550; Key, M. H.

2009-11-15

Nail-wire targets (20 {mu}m diameter copper wires with 80 {mu}m hemispherical head) were used to investigate energy transport by relativistic fast electrons generated in intense laser-plasma interactions. The targets were irradiated using the 300 J, 1 ps, and 2x10{sup 20} W{center_dot}cm{sup -2} Vulcan laser at the Rutherford Appleton Laboratory. A spherically bent crystal imager, a highly ordered pyrolytic graphite spectrometer, and single photon counting charge-coupled device gave absolute Cu K{alpha} measurements. Results show a concentration of energy deposition in the head and an approximately exponential fall-off along the wire with about 60 {mu}m 1/e decay length due to resistive inhibition.more » The coupling efficiency to the wire was 3.3{+-}1.7% with an average hot electron temperature of 620{+-}125 keV. Extreme ultraviolet images (68 and 256 eV) indicate additional heating of a thin surface layer of the wire. Modeling using the hybrid E-PLAS code has been compared with the experimental data, showing evidence of resistive heating, magnetic trapping, and surface transport.« less

Direct simulation of heat transfer in a turbulent swept flow over a wire in a channel

NASA Astrophysics Data System (ADS)

Ranjan, Reetesh; Pantano, Carlos; Fischer, Paul; Siegel, Andrew

2009-11-01

We present results from direct numerical simulations of heat transfer (considered as a passive scalar) in a turbulent swept flow across a thin, cylindrical wire in a channel. This model mimics the flow through the wire-wrapped fuel pins typical of fast neutron reactor designs. Mean flow develops both along the wire and across the wire, leading to the formation of a turbulent cross-flow regime in the channel. This leads to improvement in heat transfer properties of the channel surface due to enhancement in mixing. The friction Reynolds number in the axial direction is approximately 305. Cross-flow friction Reynolds numbers ranging from 0 to 115 are examined. Two passive scalars at Prandtl number of 1.0 and 0.01 respectively, are simulated in this study. Constant flux boundary conditions are used along the walls of the channel and adiabatic conditions are used along the surface of the wire. The numerical method uses spectral elements in the plane perpendicular to the wire axis and Fourier decomposition in the direction of the axis of the wire. The simulations use up to 107 million collocation points and were performed at the Argonne Leadership BG/P supercomputer. The passive scalar field statistics are investigated, including mean scalar field, turbulence statistics and instantaneous surface scalar distribution.

Low voltage FCC for home and business

NASA Technical Reports Server (NTRS)

Wolf, L.

1972-01-01

A thin pressure-sensitive FCC for low voltage usage is described. It is recommended for installing in speakers, intercoms, doorbells, burglar alarms, and clocks, without running wires between walls. The specifications are given.

Shape Memory Micro- and Nanowire Libraries for the High-Throughput Investigation of Scaling Effects.

PubMed

Oellers, Tobias; König, Dennis; Kostka, Aleksander; Xie, Shenqie; Brugger, Jürgen; Ludwig, Alfred

2017-09-11

The scaling behavior of Ti-Ni-Cu shape memory thin-film micro- and nanowires of different geometry is investigated with respect to its influence on the martensitic transformation properties. Two processes for the high-throughput fabrication of Ti-Ni-Cu micro- to nanoscale thin film wire libraries and the subsequent investigation of the transformation properties are reported. The libraries are fabricated with compositional and geometrical (wire width) variations to investigate the influence of these parameters on the transformation properties. Interesting behaviors were observed: Phase transformation temperatures change in the range from 1 to 72 °C (austenite finish, (A f ), 13 to 66 °C (martensite start, M s ) and the thermal hysteresis from -3.5 to 20 K. It is shown that a vanishing hysteresis can be achieved for special combinations of sample geometry and composition.

Self-transducing silicon nanowire electromechanical systems at room temperature.

PubMed

He, Rongrui; Feng, X L; Roukes, M L; Yang, Peidong

2008-06-01

Electronic readout of the motions of genuinely nanoscale mechanical devices at room temperature imposes an important challenge for the integration and application of nanoelectromechanical systems (NEMS). Here, we report the first experiments on piezoresistively transduced very high frequency Si nanowire (SiNW) resonators with on-chip electronic actuation at room temperature. We have demonstrated that, for very thin (~90 nm down to ~30 nm) SiNWs, their time-varying strain can be exploited for self-transducing the devices' resonant motions at frequencies as high as approximately 100 MHz. The strain of wire elongation, which is only second-order in doubly clamped structures, enables efficient displacement transducer because of the enhanced piezoresistance effect in these SiNWs. This intrinsically integrated transducer is uniquely suited for a class of very thin wires and beams where metallization and multilayer complex patterning on devices become impractical. The 30 nm thin SiNW NEMS offer exceptional mass sensitivities in the subzeptogram range. This demonstration makes it promising to advance toward NEMS sensors based on ultrathin and even molecular-scale SiNWs, and their monolithic integration with microelectronics on the same chip.

On the Impact of Electrostatic Correlations on the Double-Layer Polarization of a Spherical Particle in an Alternating Current Field.

PubMed

Alidoosti, Elaheh; Zhao, Hui

2018-05-15

At concentrated electrolytes, the ion-ion electrostatic correlation effect is considered an important factor in electrokinetics. In this paper, we compute, in theory and simulation, the dipole moment for a spherical particle (charged, dielectric) under the action of an alternating electric field using the modified continuum Poisson-Nernst-Planck (PNP) model by Bazant et al. [ Double Layer in Ionic Liquids: Overscreening Versus Crowding . Phys. Rev. Lett. 2011 , 106 , 046102 ] We investigate the dependency of the dipole moment in terms of frequency and its variation with such quantities like ζ-potential, electrostatic correlation length, and double-layer thickness. With thin electric double layers, we develop simple models through performing an asymptotic analysis of the modified PNP model. We also present numerical results for an arbitrary Debye screening length and electrostatic correlation length. From the results, we find a complicated impact of electrostatic correlations on the dipole moment. For instance, with increasing the electrostatic correlation length, the dipole moment decreases and reaches a minimum and then it goes up. This is because of initially decreasing of surface conduction and finally increasing due to the impact of ion-ion electrostatic correlations on ion's convection and migration. Also, we show that in contrast to the standard PNP model, the modified PNP model can qualitatively explain the data from the experimental results in multivalent electrolytes.

Chameleon gravity, electrostatics, and kinematics in the outer galaxy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pourhasan, R.; Mann, R.B.; Afshordi, N.

2011-12-01

Light scalar fields are expected to arise in theories of high energy physics (such as string theory), and find phenomenological motivations in dark energy, dark matter, or neutrino physics. However, the coupling of light scalar fields to ordinary (or dark) matter is strongly constrained from laboratory, solar system, and astrophysical tests of the fifth force. One way to evade these constraints in dense environments is through the chameleon mechanism, where the field's mass steeply increases with ambient density. Consequently, the chameleonic force is only sourced by a thin shell near the surface of dense objects, which significantly reduces its magnitude.more » In this paper, we argue that thin-shell conditions are equivalent to ''conducting'' boundary conditions in electrostatics. As an application, we use the analogue of the method of images to calculate the back-reaction (or self-force) of an object around a spherical gravitational source. Using this method, we can explicitly compute the violation of the equivalence principle in the outskirts of galactic haloes (assuming an NFW dark matter profile): Intermediate mass satellites can be slower than their larger/smaller counterparts by as much as 10% close to a thin shell.« less

An Easily Constructed and Versatile Molecular Model

NASA Astrophysics Data System (ADS)

Hernandez, Sandra A.; Rodriguez, Nora M.; Quinzani, Oscar

1996-08-01

Three-dimensional molecular models are powerful tools used in basic courses of general and organic chemistry when the students must visualize the spatial distributions of atoms in molecules and relate them to the physical and chemical properties of such molecules. This article discusses inexpensive, easily carried, and semipermanent molecular models that the students may build by themselves. These models are based upon two different types of arrays of thin flexible wires, like telephone hook-up wires, which may be bent easily but keep their shapes.

Size dependence of energetic properties in nanowire-based energetic materials

NASA Astrophysics Data System (ADS)

Menon, L.; Aurongzeb, D.; Patibandla, S.; Bhargava Ram, K.; Richter, C.; Sacco, A.

2006-08-01

We prepared nanowire-array-based thin film energetic nanocomposites based on Al -Fe2O3. The ignition properties as a function of wire dimensions and interwire spacing have been investigated. We show significant variations in ignition behavior, which we relate to the kinetic and heat transfer dynamics of the various configurations studied. Our results indicate the possibility for nanoscale control of reaction parameters such as flame temperature and burn rate in such composites for optimized configurations (optimum wire size, interwire spacing, film thickness, etc.).

Palladium-chromium static strain gage for high temperature propulsion systems

NASA Technical Reports Server (NTRS)

Lei, Jih-Fen

1991-01-01

The present electrical strain gage for high temperature static strain measurements is in its fine-wire and thin-film forms designed to be temperature-compensated on any substrate material. The gage element is of Pd-Cr alloy, while the compensator is of Pt. Because the thermally-induced apparent strain of this compensated wire strain gage is sufficiently small, with good reproducibility between thermal cycles to 800 C, output figures can be corrected within a reasonable margin of error.

Electrostatic wire for stabilizing a charged particle beam

DOEpatents

Prono, Daniel S.; Caporaso, George J.; Briggs, Richard J.

1985-01-01

In combination with a charged particle beam generator and accelerator, apparatus and method are provided for stabilizing a beam of electrically charged particles. A guiding means, disposed within the particle beam, has an electric charge induced upon it by the charged particle beam. Because the sign of the electric charge on the guiding means and the sign of the particle beam are opposite, the particles are attracted toward and cluster around the guiding means to thereby stabilize the particle beam as it travels.

Continuous-Tone Electrostatic Electrography

DTIC Science & Technology

1948-12-15

TRANSLATOR <»>: Schaf fort, R.M. Williams, D.I. WfOiwp, L*E, = TYRS. SERIES . NUMBER AND PERIOD OF R*RO«T COVERED: Quarterly Progress ropt fjT...a passing wire (a ohöft distance abo’ve tho plato) or a series qf point a or othor oourpoo of aom<^> ^mat similar geometry hold at high voltage In... temporale of tho plat©» If tho dark decay i„s not of thermal : origin, an exponential typo of decay would still ho anticipated. Ih such caoe

Beam-centroid tracking instrument for ion thrusters

NASA Astrophysics Data System (ADS)

Pollard, J. E.

1995-03-01

Thrust vector stability for an electrostatic ion engine can be measured with improved sensitivity and time resolution by the method described here. Four double-wire Langmuir probes, aligned in the form of a cross, are placed in the exhaust plume and are translated by a motorized positioning system to balance the currents collected along two orthogonal axes. The thrust vector position is thereby measured with an angular resolution of less than 0.01 deg and a response time of less than 5 sec.

Electrostatic wire stabilizing a charged particle beam

DOEpatents

Prono, D.S.; Caporaso, G.J.; Briggs, R.J.

1983-03-21

In combination with a charged particle beam generator and accelerator, apparatus and method are provided for stabilizing a beam of electrically charged particles. A guiding means, disposed within the particle beam, has an electric charge induced upon it by the charged particle beam. Because the sign of the electric charge on the guiding means and the sign of the particle beam are opposite, the particles are attracted toward and cluster around the guiding means to thereby stabilize the particle beam as it travels.

Effect of Split Gate Size on the Electrostatic Potential and 0.7 Anomaly within Quantum Wires on a Modulation-Doped GaAs /AlGaAs Heterostructure

NASA Astrophysics Data System (ADS)

Smith, L. W.; Al-Taie, H.; Lesage, A. A. J.; Thomas, K. J.; Sfigakis, F.; See, P.; Griffiths, J. P.; Farrer, I.; Jones, G. A. C.; Ritchie, D. A.; Kelly, M. J.; Smith, C. G.

2016-04-01

We study 95 split gates of different size on a single chip using a multiplexing technique. Each split gate defines a one-dimensional channel on a modulation-doped GaAs /AlGaAs heterostructure, through which the conductance is quantized. The yield of devices showing good quantization decreases rapidly as the length of the split gates increases. However, for the subset of devices showing good quantization, there is no correlation between the electrostatic length of the one-dimensional channel (estimated using a saddle-point model) and the gate length. The variation in electrostatic length and the one-dimensional subband spacing for devices of the same gate length exceeds the variation in the average values between devices of different lengths. There is a clear correlation between the curvature of the potential barrier in the transport direction and the strength of the "0.7 anomaly": the conductance value of the 0.7 anomaly reduces as the barrier curvature becomes shallower. These results highlight the key role of the electrostatic environment in one-dimensional systems. Even in devices with clean conductance plateaus, random fluctuations in the background potential are crucial in determining the potential landscape in the active device area such that nominally identical gate structures have different characteristics.

Modeling and simulations of the double-probe electric field instrument in tenuous and cold streaming plasmas

NASA Astrophysics Data System (ADS)

Miyake, Y.; Cully, C. M.; Usui, H.; Nakashima, H.

2013-12-01

In order to increase accuracy and reliability of in-situ measurements made by scientific spacecraft, it is imperative to develop comprehensive understanding of spacecraft-plasma interactions. In space environments, not only the spacecraft charging but also surrounding plasma disturbances such as caused by the wake formation may interfere directly with in-situ measurements. The self-consistent solutions of such phenomena are necessary to assess their effects on scientific spacecraft systems. As our recent activity, we work on the modeling and simulations of Cluster double-probe instrument in tenuous and cold streaming plasmas [1]. Double-probe electric field sensors are often deployed using wire booms with radii much less than typical Debye lengths of magnetospheric plasmas (millimeters compared to tens of meters). However, in tenuous and cold streaming plasmas seen in the polar cap and lobe regions, the wire booms have a high positive potential due to photoelectron emission and can strongly scatter approaching ions. Consequently, an electrostatic wake formed behind the spacecraft is further enhanced by the presence of the wire booms. We reproduce this process for the case of the Cluster satellite by performing plasma particle-in-cell (PIC) simulations [2], which include the effects of both the spacecraft body and the wire booms in a simultaneous manner, on modern supercomputers. The simulations reveal that the effective thickness of the booms for the Cluster Electric Field and Wave (EFW) instrument is magnified from its real thickness (2.2 millimeters) to several meters, when the spacecraft potential is at 30-40 volts. Such booms enhance the wake electric field magnitude by a factor of about 2 depending on the spacecraft potential, and play a principal role in explaining the in situ Cluster EFW data showing sinusoidal spurious electric fields of about 10 mV/m amplitudes. The boom effects are quantified by comparing PIC simulations with and without wire booms. The paper also reports some recent progress of ongoing PIC simulation research that focuses on spurious electric field generation in subsonic ion flows. Our preliminary simulation results revealed that; (1) there is no apparent wake signature behind the spacecraft in such a condition, but (2) spurious electric field over 1 mV/m amplitude is observed in the direction of the flow vector. The observed field amplitude is sometimes comparable to the convection electric field (a few mV/m) associated with the flow. Our analysis also confirmed that the spurious field is caused by a weakly-asymmetric potential pattern created by the ion flow. We will present the parametric study of such spurious fields for various conditions of plasma flows. [References] [1] Miyake, Y., C. M. Cully, H. Usui, and H. Nakashima (2013), Plasma particle simulations of wake formation behind a spacecraft with thin wire booms, submitted to J. Geophys. Res. [2] Miyake, Y., and H. Usui (2009), New electromagnetic particle simulation code for the analysis of spacecraft-plasma interactions, Phys. Plasmas, 16, 062904, doi:10.1063/1.3147922.

Motor for High Temperature Applications

NASA Technical Reports Server (NTRS)

Roopnarine (Inventor)

2013-01-01

A high temperature motor has a stator with poles formed by wire windings, and a rotor with magnetic poles on a rotor shaft positioned coaxially within the stator. The stator and rotor are built up from stacks of magnetic-alloy laminations. The stator windings are made of high temperature magnet wire insulated with a vitreous enamel film, and the wire windings are bonded together with ceramic binder. A thin-walled cylinder is positioned coaxially between the rotor and the stator to prevent debris from the stator windings from reaching the rotor. The stator windings are wound on wire spools made of ceramic, thereby avoiding need for mica insulation and epoxy/adhesive. The stator and rotor are encased in a stator housing with rear and front end caps, and rear and front bearings for the rotor shaft are mounted on external sides of the end caps to keep debris from the motor migrating into the bearings' races.

The Fine Wire Technique for Flexor Tenolysis.

PubMed

Rosenblum, Matthew K; Baltodano, Pablo A; Weinberg, Maxene H; Whipple, Lauren A; Gemmiti, Amanda L; Whipple, Richard E

2017-11-01

Flexor tenolysis surgery for flexor digitorum profundus and superficialis adhesions is a common procedure performed by hand surgeons. Releasing these adhered tendons can greatly improve hand function and improve quality of life. Recent evidence, however, has shown that the outcomes of tenolysis surgeries are often suboptimal and can result in relapsing adhesions or even tendon ruptures. This article describes a new technique with potential for reduced complication rates: The Fine Wire Technique for Flexor Tenolysis (FWT). Following FWT, the patient detailed in this article had an excellent recovery of function and no complications: including tendon rupture, infection, hematomas, or any other complications. She reported a major improvement from her preoperative functionality and continues to have this level of success. The wire's thinness allows for a swift tenolysis. The FWT is a new option available to the hand surgeon associated with good functional results. The wire is readily available to the clinician and is also inexpensive.

Effect of fluoride prophylactic agents on the mechanical properties of nickel-titanium-based orthodontic wires.

PubMed

Walker, Mary P; White, Richard J; Kula, Katherine S

2005-06-01

Titanium-based alloys have high corrosion resistance because they form a thin, stable oxide layer. Nevertheless, fluoride prophylactic agents can cause corrosion and associated discoloration of titanium-based orthodontic wires. The purpose of this investigation was to study the effects of fluoride prophylactic agents on the mechanical properties of nickel-titanium (Ni-Ti) and copper-nickel-titanium (Cu-Ni-Ti) orthodontic archwires. Preformed rectangular Ni-Ti and Cu-Ni-Ti wires were immersed in either an acidulated fluoride agent, a neutral fluoride agent, or distilled water (control) for 1.5 hours at 37 degrees C. After immersion, the loading and unloading elastic modulus and yield strength of the wires were measured with a 3-point bend test in a water bath at 37 degrees C, in accordance with the criteria in the current American National Standard/American Dental Association Specification No. 32 for Orthodontic Wires (2000). Scanning electron microscopy was also used to characterize the effects of the fluoride treatment on the wire topography. Unloading mechanical properties of Ni-Ti orthodontic wires were significantly decreased after exposure to both fluoride agents (1-way analysis of variance [ANOVA] and Dunnett's post hoc, alpha =.05); however, Cu-Ni-Ti wire mechanical properties were not significantly affected by either fluoride agent (1-way ANOVA, alpha =.05). Corrosive changes in surface topography were observed for both wires, with Cu-Ni-Ti appearing to be more severely affected. The results suggest that using topical fluoride agents with Ni-Ti wire could decrease the functional unloading mechanical properties of the wire and contribute to prolonged orthodontic treatment.

STRUCTURE AND HIGH-FIELD PERFORMANCE OF JELLY ROLL PROCESSED Nb{sub 3}Sn WIRES USING Sn-Ta AND Sn-Ti BASED ALLOY SHEET

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tachikawa, K.; Tsuyuki, T.; Hayashi, Y.

Sn-Ta based alloy buttons of different compositions were prepared by the melt diffusion process among constituent metal powders, and then pressed into plates. Meanwhile Sn-Ti based alloy plates were sliced from the melt and cast ingot. Resulting Sn-based alloy plates were rolled into thin sheets. The Sn-based alloy sheet was laminated with a Nb sheet, and wound into a Jelly Roll (JR) composite. The composite was encased in a sheath, and fabricated into a thin wire followed by the heat treatment. The application of hydrostatic extrusion is useful at the initial stage of the fabrication. The JR wires using Sn-Tamore » and Sn-Ti based alloy sheets show a non-Cu J{sub c} of {approx}250 A/mm{sup 2} and {approx}150 A/mm{sup 2} at 20 T and 22 T, respectively, at 4.2 K. It has been found that the Nb impregnates into the Sn-based alloy layers during the reaction, and Nb{sub 3}Sn layers are synthesized by the mutual diffusion between the Nb sheet and the Sn-based alloy sheet without formation of voids. Sn-Ti based alloy sheets are attractive due to their easiness of mass production. Structure and high-field performance of JR processed Nb{sub 3}Sn wires prepared from Sn-based alloy sheets with different compositions are compared in this article.« less

Radius correction formula for capacitances and effective length vectors of monopole and dipole antenna systems

NASA Astrophysics Data System (ADS)

Macher, W.; Oswald, T. H.

2011-02-01

In the investigation of antenna systems which consist of one or several monopoles, a realistic modeling of the monopole radii is not always feasible. In particular, physical scale models for electrolytic tank measurements of effective length vectors (rheometry) of spaceborne monopoles are so small that a correct scaling of monopole radii often results in very thin, flexible antenna wires which bend too much under their own weight. So one has to use monopoles in the model which are thicker than the correct scale diameters. The opposite case, where the monopole radius has to be modeled too thin, appears with certain numerical antenna programs based on wire grid modeling. This problem arises if the underlying algorithm assumes that the wire segments are much longer than their diameters. In such a case it is eventually not possible to use wires of correct thickness to model the monopoles. In order that these numerical and experimental techniques can be applied nonetheless to determine the capacitances and effective length vectors of such monopoles (with an inaccurate modeling of monopole diameters), an analytical correction method is devised. It enables one to calculate the quantities for the real antenna system from those obtained for the model antenna system with wrong monopole radii. Since a typical application of the presented formalism is the analysis of spaceborne antenna systems, an illustration for the monopoles of the WAVES experiment on board the STEREO-A spacecraft is given.

Self Healing Coating/Film Project

NASA Technical Reports Server (NTRS)

Summerfield, Burton; Thompson, Karen; Zeitlin, Nancy; Mullenix, Pamela; Calle, Luz; Williams, Martha

2015-01-01

Kennedy Space Center (KSC) has been developing self healing materials and technologies. This project seeks to further develop self healing functionality in thin films for applications such as corrosion protective coatings, inflatable structures, space suit materials, and electrical wire insulation.

Electrostatic energy and screened charge interaction near the surface of metals with different Fermi surface shape

NASA Astrophysics Data System (ADS)

Gabovich, A. M.; Il'chenko, L. G.; Pashitskii, E. A.; Romanov, Yu. A.

1980-04-01

Using the Poisson equation Green function for a self-consistent field in a spatially inhomogeneous system, expressions for the electrostatic energy and screened charge interaction near the surface of a semi-infinite metal and a thin quantizing film are derived. It is shown that the decrease law and Friedel oscillation amplitude of adsorbed atom indirect interaction are determined by the electron spectrum character and the Fermi surface shape. The results obtained enable us to explain, in particular, the submonolayer adsorbed film structure on the W and Mo surfaces.

Structural phase transition in monolayer MoTe2 driven by electrostatic doping

NASA Astrophysics Data System (ADS)

Wang, Ying; Xiao, Jun; Zhu, Hanyu; Li, Yao; Alsaid, Yousif; Fong, King Yan; Zhou, Yao; Wang, Siqi; Shi, Wu; Wang, Yuan; Zettl, Alex; Reed, Evan J.; Zhang, Xiang

2017-10-01

Monolayers of transition-metal dichalcogenides (TMDs) exhibit numerous crystal phases with distinct structures, symmetries and physical properties. Exploring the physics of transitions between these different structural phases in two dimensions may provide a means of switching material properties, with implications for potential applications. Structural phase transitions in TMDs have so far been induced by thermal or chemical means; purely electrostatic control over crystal phases through electrostatic doping was recently proposed as a theoretical possibility, but has not yet been realized. Here we report the experimental demonstration of an electrostatic-doping-driven phase transition between the hexagonal and monoclinic phases of monolayer molybdenum ditelluride (MoTe2). We find that the phase transition shows a hysteretic loop in Raman spectra, and can be reversed by increasing or decreasing the gate voltage. We also combine second-harmonic generation spectroscopy with polarization-resolved Raman spectroscopy to show that the induced monoclinic phase preserves the crystal orientation of the original hexagonal phase. Moreover, this structural phase transition occurs simultaneously across the whole sample. This electrostatic-doping control of structural phase transition opens up new possibilities for developing phase-change devices based on atomically thin membranes.

On the convergence of an iterative formulation of the electromagnetic scattering from an infinite grating of thin wires

NASA Technical Reports Server (NTRS)

Brand, J. C.

1985-01-01

Contraction theory is applied to an iterative formulation of electromagnetic scattering from periodic structures and a computational method for insuring convergence is developed. A short history of spectral (or k-space) formulation is presented with an emphasis on application to periodic surfaces. The mathematical background for formulating an iterative equation is covered using straightforward single variable examples including an extension to vector spaces. To insure a convergent solution of the iterative equation, a process called the contraction corrector method is developed. Convergence properties of previously presented iterative solutions to one-dimensional problems are examined utilizing contraction theory and the general conditions for achieving a convergent solution are explored. The contraction corrector method is then applied to several scattering problems including an infinite grating of thin wires with the solution data compared to previous works.

Near-wall turbulence alteration through thin streamwise riblets

NASA Technical Reports Server (NTRS)

Wilkinson, Stephen P.; Lazos, Barry S.

1987-01-01

The possibility of improving the level of drag reduction associated with near-wall riblets is considered. The methodology involves the use of a hot-wire anemometer to study various surface geometries on small, easily constructed models. These models consist of small, adjacent rectangular channels on the wall aligned in the streamwise direction. The VITA technique is modified and applied to thin-element-array and smooth flat-plate data and the results are indicated schematically.

Beam Position and Phase Monitor - Wire Mapping System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Watkins, Heath A; Shurter, Robert B.; Gilpatrick, John D.

2012-04-10

The Los Alamos Neutron Science Center (LANSCE) deploys many cylindrical beam position and phase monitors (BPPM) throughout the linac to measure the beam central position, phase and bunched-beam current. Each monitor is calibrated and qualified prior to installation to insure it meets LANSCE requirements. The BPPM wire mapping system is used to map the BPPM electrode offset, sensitivity and higher order coefficients. This system uses a three-axis motion table to position the wire antenna structure within the cavity, simulating the beam excitation of a BPPM at a fundamental frequency of 201.25 MHz. RF signal strength is measured and recorded formore » the four electrodes as the antenna position is updated. An effort is underway to extend the systems service to the LANSCE facility by replacing obsolete electronic hardware and taking advantage of software enhancements. This paper describes the upgraded wire positioning system's new hardware and software capabilities including its revised antenna structure, motion control interface, RF measurement equipment and Labview software upgrades. The main purpose of the wire mapping system at LANSCE is to characterize the amplitude response versus beam central position of BPPMs before they are installed in the beam line. The wire mapping system is able to simulate a beam using a thin wire and measure the signal response as the wire position is varied within the BPPM aperture.« less

Electro-osmosis over inhomogeneously charged surfaces in presence of non-electrostatic ion-ion interactions

NASA Astrophysics Data System (ADS)

Ghosh, Uddipta; Chakraborty, Suman

2016-06-01

In this study, we attempt to bring out a generalized formulation for electro-osmotic flows over inhomogeneously charged surfaces in presence of non-electrostatic ion-ion interactions. To this end, we start with modified electro-chemical potential of the individual species and subsequently use it to derive modified Nernst-Planck equation accounting for the ionic fluxes generated because of the presence of non-electrostatic potential. We establish what we refer to as the Poisson-Helmholtz-Nernst-Planck equations, coupled with the Navier-Stokes equations, to describe the complete transport process. Our analysis shows that the presence of non-electrostatic interactions between the ions results in an excess body force on the fluid, and modifies the osmotic pressure as well, which has hitherto remained unexplored. We further apply our analysis to a simple geometry, in an effort to work out the Smoluchowski slip velocity for thin electrical double layer limits. To this end, we employ singular perturbation and develop a general framework for the asymptotic analysis. Our calculations reveal that the final expression for slip velocity remains the same as that without accounting for non-electrostatic interactions. However, the presence of non-electrostatic interactions along with ion specificity can significantly change the quantitative behavior of Smoluchowski slip velocity. We subsequently demonstrate that the presence of non-electrostatic interactions may significantly alter the effective interfacial potential, also termed as the "Zeta potential." Our analysis can potentially act as a guide towards the prediction and possibly quantitative determination of the implications associated with the existence of non-electrostatic potential, in an electrokinetic transport process.

Self-Powered Electrostatic Filter with Enhanced Photocatalytic Degradation of Formaldehyde Based on Built-in Triboelectric Nanogenerators.

PubMed

Feng, Yawei; Ling, Lili; Nie, Jinhui; Han, Kai; Chen, Xiangyu; Bian, Zhenfeng; Li, Hexing; Wang, Zhong Lin

2017-12-26

Recently, atmospheric pollution caused by particulate matter or volatile organic compounds (VOCs) has become a serious issue to threaten human health. Consequently, it is highly desirable to develop an efficient purifying technique with simple structure and low cost. In this study, by combining a triboelectric nanogenerator (TENG) and a photocatalysis technique, we demonstrated a concept of a self-powered filtering method for removing pollutants from indoor atmosphere. The photocatalyst P25 or Pt/P25 was embedded on the surface of polymer-coated stainless steel wires, and such steel wires were woven into a filtering network. A strong electric field can be induced on this filtering network by TENG, while both electrostatic adsorption effect and TENG-enhanced photocatalytic effect can be achieved. Rhodamine B (RhB) steam was selected as the pollutant for demonstration. The absorbed RhB on the filter network with TENG in 1 min was almost the same amount of absorption achieved in 15 min without using TENG. Meanwhile, the degradation of RhB was increased over 50% under the drive of TENG. Furthermore, such a device was applied for the degradation of formaldehyde, where degradation efficiency was doubled under the drive of TENG. This work extended the application for the TENG in self-powered electrochemistry, design and concept of which can be possibly applied in the field of haze governance, indoor air cleaning, and photocatalytic pollution removal for environmental protection.

Test progress on the electrostatic membrane reflector

NASA Technical Reports Server (NTRS)

Mihora, D. J.

1981-01-01

An extemely lightweight type of precision reflector antenna, being developed for potential deployment from the space shuttle, uses electrostatic forces to tension a thin membrane and form it into a concave reflector surface. The typical shuttle-deployed antenna would have a diameter of 100 meters and an RMS surface smoothness of 10 to 1 mm for operation at 1 to 10 GHz. NASA Langley Research Center built and is currently testing a subscale (16 foot diameter) model of the membrane reflector portion of such an antenna. Preliminary test results and principal factors affecting surface quality are addressed. Factors included are the effect of the perimeter boundary, splicing of the membrane, the long-scale smoothness of commercial membranes, and the spatial controllability of the membrane using voltage adjustments to alter the electrostatic pressure. Only readily available commercial membranes are considered.

Blast Coating of Superelastic NiTi Wire with PTFE to Enhance Wear Properties

NASA Astrophysics Data System (ADS)

Dunne, Conor F.; Roche, Kevin; Twomey, Barry; Hodgson, Darel; Stanton, Kenneth T.

2015-03-01

This work investigates the deposition of polytetrafluoroethylene (PTFE) onto a superelastic NiTi wire using an ambient temperature-coating technique known as CoBlast. The process utilises a stream of abrasive (Al2O3) and a coating medium (PTFE) sprayed simultaneously at the surface of the substrate. Superelastic NiTi wire is used in guidewire applications, and PTFE coatings are commonly applied to reduce damage to vessel walls during insertion and removal, and to aid in accurate positioning by minimising the force required to advance, retract or rotate the wire. The CoBlast coated wires were compared to wire treated with PTFE only. The coated samples were examined using variety of techniques: X-ray diffraction (XRD), microscopy, surface roughness, wear testing and flexural tests. The CoBlast coated samples had an adherent coating with a significant resistance to wear compared to the samples coated with PTFE only. The XRD revealed that the process gave rise to a stress-induced martensite phase in the NiTi which may enhance mechanical properties. The study indicates that the CoBlast process can be used to deposit thin adherent coatings of PTFE onto the surface of superelastic NiTi.

Designing an efficient rectifying cut-wire metasurface for electromagnetic energy harvesting

NASA Astrophysics Data System (ADS)

Oumbé Tékam, Gabin T.; Ginis, Vincent; Danckaert, Jan; Tassin, Philippe

2017-02-01

Electromagnetic energy harvesting, i.e., capturing energy from ambient microwave signals, may become an essential part in extending the battery lifetime of wearable devices. Here, we present a design of a microwave energy harvester based on a cut-wire metasurface with an integrated PN junction diode. The cut wire with a quasistatic electric-dipole moment is designed to have a resonance at 6.75 GHz, leading to a substantial cross-section for absorption. The external microwaves create a unidirectional current through the rectifying action of the integrated diode. Using an electrical-circuit model, we design the operating frequency and the resistive load of the cut wire. Subsequently, by optimizing our design using full-wave numerical simulations, we obtain an energy harvesting efficiency of 50% for incident power densities in agreement with the typical power density of WiFi signals. Finally, we study the effect of connecting adjacent unit cells of the metasurface in parallel by a thin highly inductive wire and we demonstrate that this allows for the collection of current from all individual cells, while the microwave resonance of the unit cell is not significantly altered, thus solving the wiring problem that arises in many nonlinear metamaterials.

Thin film temperature sensor

NASA Technical Reports Server (NTRS)

Grant, H. P.; Przybyszewski, J. S.

1980-01-01

Thin film surface temperature sensors were developed. The sensors were made of platinum-platinum/10 percent rhodium thermocouples with associated thin film-to-lead wire connections and sputtered on aluminum oxide coated simulated turbine blades for testing. Tests included exposure to vibration, low velocity hydrocarbon hot gas flow to 1250 K, and furnace calibrations. Thermal electromotive force was typically two percent below standard type S thermocouples. Mean time to failure was 42 hours at a hot gas flow temperature of 1250 K and an average of 15 cycles to room temperature. Failures were mainly due to separation of the platinum thin film from the aluminum oxide surface. Several techniques to improve the adhesion of the platinum are discussed.

Electrochemical Corrosion Properties of Commercial Ultra-Thin Copper Foils

NASA Astrophysics Data System (ADS)

Yen, Ming-Hsuan; Liu, Jen-Hsiang; Song, Jenn-Ming; Lin, Shih-Ching

2017-08-01

Ultra-thin electrodeposited Cu foils have been developed for substrate thinning for mobile devices. Considering the corrosion by residual etchants from the lithography process for high-density circuit wiring, this study investigates the microstructural features of ultra-thin electrodeposited Cu foils with a thickness of 3 μm and their electrochemical corrosion performance in CuCl2-based etching solution. X-ray diffraction and electron backscatter diffraction analyses verify that ultra-thin Cu foils exhibit a random texture and equi-axed grains. Polarization curves show that ultra-thin foils exhibit a higher corrosion potential and a lower corrosion current density compared with conventional (220)-oriented foils with fan-like distributed fine-elongated columnar grains. Chronoamperometric results also suggest that ultra-thin foils possess superior corrosion resistance. The passive layer, mainly composed of CuCl and Cu2O, forms and dissolves in sequence during polarization.

Bright and durable field-emission source derived from frozen refractory-metal Taylor cones

DOE PAGES

Hirsch, Gregory

2017-02-22

A novel method for creating conical field-emission structures possessing unusual and desirable physical characteristics is described. This process is accomplished by solidification of electrostatically formed high-temperature Taylor cones created on the ends of laser melted refractory-metal wires. Extremely rapid freezing ensures that the resultant solid structures preserve the shape and surface smoothness of the flawless liquid Taylor-cones to a very high degree. The method also enables in situ and rapid restoration of the frozen cones to their initial pristine state after undergoing physical degradation during use. This permits maximum current to be delivered without excessive concern for any associated reductionmore » in field-emitter lifetime resulting from operation near or even above the damage threshold. In addition to the production of field emitters using polycrystalline wires as a substrate, the feasibility of producing monocrystalline frozen Taylor-cones having reproducible crystal orientation by growth on single-crystal wires was demonstrated. Finally, the development of the basic field-emission technology, progress to incorporate it into a pulsed electron gun employing laser-assisted field emission for ultrafast experiments, and some additional advances and opportunities are discussed.« less

Morphological Control of GaN and Its Effect within Electrochemical Heterojunctions

DOE PAGES

Parameshwaran, Vijay; Clemens, Bruce

2016-08-17

With morphological control through a solid source chemical vapor deposition process, GaN polycrystalline films, single-crystal nanowires, and mixed film/wires are grown on silicon to form a heterojunction that is a basis for III-V nitride device development. By contacting the GaN/Si structure to the CoCp 2 0/ + redox pair and performing impedance spectroscopy measurements, the band diagram of this junction is built for these three configurations. This serves as a basis for understanding the electrical nature of III-V nitride/Si interfaces that exist in several photonic device technologies, especially in context of using GaN nanomaterials grown on silicon for various applications.more » When these junctions are exposed to low-power UV illumination in contact with the Fc/Fc + redox pair, photocurrents of 18, 110, and 482 nA/cm 2 are generated for the nanowires, mixed film/wires, and films respectively. These currents, along with the electrostatics investigated through the impedance spectroscopy, show the trends of photoconversion with GaN morphology in this junction. Furthermore, they suggest that the mixed film/wires are a promising design for solar-based applications such as photovoltaics and water splitting electrodes.« less

Bright and durable field-emission source derived from frozen refractory-metal Taylor cones

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hirsch, Gregory

A novel method for creating conical field-emission structures possessing unusual and desirable physical characteristics is described. This process is accomplished by solidification of electrostatically formed high-temperature Taylor cones created on the ends of laser melted refractory-metal wires. Extremely rapid freezing ensures that the resultant solid structures preserve the shape and surface smoothness of the flawless liquid Taylor-cones to a very high degree. The method also enables in situ and rapid restoration of the frozen cones to their initial pristine state after undergoing physical degradation during use. This permits maximum current to be delivered without excessive concern for any associated reductionmore » in field-emitter lifetime resulting from operation near or even above the damage threshold. In addition to the production of field emitters using polycrystalline wires as a substrate, the feasibility of producing monocrystalline frozen Taylor-cones having reproducible crystal orientation by growth on single-crystal wires was demonstrated. Finally, the development of the basic field-emission technology, progress to incorporate it into a pulsed electron gun employing laser-assisted field emission for ultrafast experiments, and some additional advances and opportunities are discussed.« less

Morphological Control of GaN and Its Effect within Electrochemical Heterojunctions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parameshwaran, Vijay; Clemens, Bruce

With morphological control through a solid source chemical vapor deposition process, GaN polycrystalline films, single-crystal nanowires, and mixed film/wires are grown on silicon to form a heterojunction that is a basis for III-V nitride device development. By contacting the GaN/Si structure to the CoCp 2 0/ + redox pair and performing impedance spectroscopy measurements, the band diagram of this junction is built for these three configurations. This serves as a basis for understanding the electrical nature of III-V nitride/Si interfaces that exist in several photonic device technologies, especially in context of using GaN nanomaterials grown on silicon for various applications.more » When these junctions are exposed to low-power UV illumination in contact with the Fc/Fc + redox pair, photocurrents of 18, 110, and 482 nA/cm 2 are generated for the nanowires, mixed film/wires, and films respectively. These currents, along with the electrostatics investigated through the impedance spectroscopy, show the trends of photoconversion with GaN morphology in this junction. Furthermore, they suggest that the mixed film/wires are a promising design for solar-based applications such as photovoltaics and water splitting electrodes.« less

In-Situ Wire Damage Detection System

NASA Technical Reports Server (NTRS)

Jolley, Scott T. (Inventor); Gibson, Tracy L. (Inventor); Medelius, Pedro J. (Inventor); Roberson, Luke B. (Inventor); Tate, Lanetra C. (Inventor); Smith, Trent M. (Inventor); Williams, Martha K. (Inventor)

2014-01-01

An in-situ system for detecting damage in an electrically conductive wire. The system includes a substrate at least partially covered by a layer of electrically conductive material forming a continuous or non-continuous electrically conductive layer connected to an electrical signal generator adapted to delivering electrical signals to the electrically conductive layer. Data is received and processed to identify damage to the substrate or electrically conductive layer. The electrically conductive material may include metalized carbon fibers, a thin metal coating, a conductive polymer, carbon nanotubes, metal nanoparticles or a combination thereof.

Subcutaneous electrode structure

NASA Technical Reports Server (NTRS)

Lund, G. F. (Inventor)

1980-01-01

A subcutaneous electrode structure suitable for a chronic implant and for taking a low noise electrocardiogram of an active animal, comprises a thin inflexible, smooth disc of stainless steel having a diameter as of 5 to 30 mm, which is sutured in place to the animal being monitored. The disc electrode includes a radially directed slot extending in from the periphery of the disc for approximately 1/3 of the diameter. Electrical connection is made to the disc by means of a flexible lead wire that extends longitudinally of the slot and is woven through apertures in the disc and held at the terminal end by means of a spot welded tab. Within the slot, an electrically insulative sleeve, such as silicone rubber, is placed over the wire. The wire with the sleeve mounted thereon is captured in the plane of the disc and within the slot by means of crimping tabs extending laterally of the slot and over the insulative wire. The marginal lip of the slot area is apertured and an electrically insulative potting material such as silicone rubber, is potted in place overlaying the wire slot region and through the apertures.

Development of LaRC (TM): IA thermoplastic polyimide coated aerospace wiring

NASA Technical Reports Server (NTRS)

Keating, Jack

1995-01-01

NASA Langley has invented LaRC(exp TM) IA and IAX which are thermoplastic polyimides with good melting, thermal and chemical resistance properties. It was the objective of this contract to prepare and extrude LaRC (exp TM) polyimide onto aircraft wire and evaluate the polymers performance in this critical application. Based on rheology and chemical resistance studies at Imitec, LaRC (exp TM) IAX melts readily in an extruder, facilitating the manufacture of thin wall coatings. The polyimide does not corode the extruder, develop gel particles nor advance in viscosity. The insulated wire was tested according to MiL-W-22759E test specifications. The resulting wire coated with LaRC (exp TM) IAX displayed exceptional properties: surface resistance, non blocking, non burning, hot fluid resistance, impulse dielectric, insulation resistance, low temperature flexibility, thermal aging, wire weight, dimensions, negligible high temperature shrinkage and stripability. The light weight and other properties merit its application in satellites, missiles and aircraft applications. The extruded IAX results in a polyimide aircraft insulation without seams, outstanding moisture resistance, continuous lengths and abrasion resistance.

Electrostatically assisted fabrication of silver-dielectric core/shell nanoparticles thin film capacitor with uniform metal nanoparticle distribution and controlled spacing.

PubMed

Li, Xue; Niitsoo, Olivia; Couzis, Alexander

2016-03-01

An electrostatically-assisted strategy for fabrication of thin film composite capacitors with controllable dielectric constant (k) has been developed. The capacitor is composed of metal-dielectric core/shell nanoparticle (silver/silica, Ag@SiO2) multilayer films, and a backfilling polymer. Compared with the simple metal particle-polymer mixtures where the metal nanoparticles (NP) are randomly dispersed in the polymer matrix, the metal volume fraction in our capacitor was significantly increased, owing to the densely packed NP multilayers formed by the electrostatically assisted assembly process. Moreover, the insulating layer of silica shell provides a potential barrier that reduces the tunneling current between neighboring Ag cores, endowing the core/shell nanocomposites with a stable and relatively high dielectric constant (k) and low dielectric loss (D). Our work also shows that the thickness of the SiO2 shell plays a dominant role in controlling the dielectric properties of the nanocomposites. Control over metal NP separation distance was realized not only by variation the shell thickness of the core/shell NPs but also by introducing a high k nanoparticle, barium strontium titanate (BST) of relatively smaller size (∼8nm) compared to 80-160nm of the core/shell Ag@SiO2 NPs. The BST assemble between the Ag@SiO2 and fill the void space between the closely packed core/shell NPs leading to significant enhancement of the dielectric constant. This electrostatically assisted assembly method is promising for generating multilayer films of a large variety of NPs over large areas at low cost. Copyright © 2015 Elsevier Inc. All rights reserved.

Young's modulus measurement of aluminum thin film with cantilever structure

NASA Astrophysics Data System (ADS)

Lee, ByoungChan; Lee, SangHun; Lee, Hwasu; Shin, Hyungjae

2001-09-01

Micromachined cantilever structures are commonly used for measuring mechanical properties of thin film materials in MEMS. The application of conventional cantilever theory in experiment raises severe problem. The deformation of the supporting post and flange is produced by the applied electrostatic force and lead to more reduced measurement value than real Young's modulus of thin film materials. In order to determine Young's modulus of aluminum thin film robustly and reproducibly, the modified cantilever structure is proposed. Two measurement methods, which are cantilever tip deflection measurement and resonant frequency measurement, are used for confirming the reliability of the proposed cantilever structure as well. Measured results indicate that the proposed measurement scheme provides useful and credible Young's modulus value for thin film materials with sub-micron thickness. The proved validation of the proposed scheme makes sure that in addition to Young's modulus of aluminum thin film, that of other thin film materials which are aluminum alloy, metal, and so forth, can be extracted easily and clearly.

Preparation, mechanical strengths, and thermal

NASA Astrophysics Data System (ADS)

Inoue, A.; Furukawa, S.; Hagiwara, M.; Masumoto, T.

1987-05-01

Ni-based amorphous wires with good bending ductility have been prepared for Ni75Si8B17 and Ni78P12B10 alloys containing 1 to 2 at. pct Al or Zr by melt spinning in rotating water. The enhancement of the wire-formation tendency by the addition of Al has been clarified to be due to the increase in the stability of the melt jet through the formation of a thin A12O3 film on the outer surface. The maximum wire diameter is about 190 to 200 μm for the Ni-Si (or P)-B-Al alloys and increases to about 250 μm for the Ni-Si-B-Al-Cr alloys containing 4 to 6 at. pct Cr. The tensile fracture strength and fracture elongation are 2730 MPa and 2.9 pct for (Ni0.75Si0.08B0.17 99Al1) wire and 2170 MPa and 2.4 pct for (Ni0.78P0.12B0.1)99Al1 wire. These wires exhibit a fatigue limit under dynamic bending strain in air with a relative humidity of 65 pct; this limit is 0.50 pct for a Ni-Si-B-Al wire, which is higher by 0.15 pct than that of a Fe75Si10B15 amorphous wire. Furthermore, the Ni-base wires do not fracture during a 180-deg bending even for a sample annealed at temperatures just below the crystallization temperature, in sharp contrast to high embrittlement tendency for Fe-base amorphous alloys. Thus, the Ni-based amorphous wires have been shown to be an attractive material similar to Fe- and Co-based amorphous wires because of its high static and dynamic strength, high ductility, high stability to thermal embrittlement, and good corrosion resistance.

Effects of electron recirculation on a hard x-ray source observed during the interaction of a high intensity laser pulse with thin Au targets

NASA Astrophysics Data System (ADS)

Compant La Fontaine, A.; Courtois, C.; Lefebvre, E.; Bourgade, J. L.; Landoas, O.; Thorp, K.; Stoeckl, C.

2013-12-01

The interaction of a high intensity laser pulse on the preplasma of a high-Z solid target produced by the pulse's pedestal generates high-energy electrons. These electrons subsequently penetrate inside the solid target and produce bremsstrahlung photons, generating an x-ray source which can be used for photonuclear studies or to radiograph high area density objects. The source characteristics are compared for targets with thin (20 μm) and thick (100 μm) Au foils on the Omega EP laser at Laboratory for Laser Energetics. Simulations using the particle-in-cell code CALDER show that for a 20 μm thickness Au target, electrons perform multiple round-trips in the target under the effect of the laser ponderomotive potential and the target electrostatic potential. These relativistic electrons have random transverse displacements, with respect to the target normal, attributed to electrostatic fluctuation fields. As a result, the x-ray spot size is increased by a factor 2 for thin target compared to thick targets, in agreement with experimental results. In addition, the computed doses agree with the measured ones provided that electron recirculation in the thin target is taken into account. A dose increase by a factor 1.7 is then computed by allowing for recirculation. In the 100 μm target case, on the other hand, this effect is found to be negligible.

High Resolution Adjustable Mirror Control for X-ray Astronomy

NASA Astrophysics Data System (ADS)

Trolier-McKinstry, Susan

We propose to build and test thin film transistor control circuitry for a new highresolution adjustable X-ray mirror technology. This control circuitry will greatly simplify the wiring scheme to address individual actuator cells. The result will be a transformative improvement for the X-ray Surveyor mission concept: mathematical models, which fit the experimental data quite well, indicate that 0.5 arcsecond imaging is feasible through this technique utilizing thin slumped glass substrates with uncorrected angular resolution of order 5-10 arcseconds. In order to correct for figures errors in a telescope with several square meters of collecting area, millions of actuator cells must be set and held at specific voltages. It is clearly not feasible to do this via millions of wires, each one connected to an actuator. Instead, we propose to develop and test thin-film technology that operates on the same principle as megapixel computer screens. We will develop the technologies needed to build thin film piezoelectric actuators, controlled by thin film ZnO transistors, on flexible polyimide films, and to connect those films to the back surfaces of X-ray mirrors on thin glass substrates without deforming the surface. These technologies represent a promising avenue of the development of mirrors for the X-Ray Surveyor mission concept. Such a telescope will make possible detailed studies of a wide variety of astrophysical sources. One example is the Warm-Hot Intergalactic Medium (WHIM), which is thought to account for a large fraction of the normal matter in the universe but which has not been detected unambiguously to date. Another is the growth of supermassive black holes in the early universe. This proposal supports NASA's goals of technical advancement of technologies suitable for future missions, and training of graduate students.

Force on an Asymmetric Capacitor

DTIC Science & Technology

2003-06-01

antigravity devices, or devices that demonstrate that there is an interaction of gravity with electric phenomena.) The thin wire electrode must be at a...September 2002) American Antigravity . http://tventura.hypermart.net/index.html (accessed September 2002). 2. Stein, W. B. Electrokinetic Propulsion

Study on brush of moving electrode type electrostatic precipitator (MEEP)

NASA Astrophysics Data System (ADS)

Zhao, Haibao; He, Yuzhong; Yao, Yuping

2018-02-01

MEEP was an efficient particle removal technology for coal plant and sintering machine. As the stability of brush in MEEP was relatively poor, the experiments was designed for the brush which was made by 0Cr18Ni9 stainless steel wire to find the failure mode and cause. Combining the results of the experiments, the failure models of brushes were different under different conditions and the brushes were suitable for being used in the condition of small diameter particles. And the life span of brushes can be more than 6 years.

Designing Diameter-Modulated Heterostructure Nanowires of PbTe/Te by Controlled Dewetting.

PubMed

Kumar, Abinash; Kundu, Subhajit; Samantaray, Debadarshini; Kundu, Paromita; Zanaga, Daniele; Bals, Sara; Ravishankar, N

2017-12-13

Heterostructures consisting of semiconductors with controlled morphology and interfaces find applications in many fields. A range of axial, radial, and diameter-modulated nanostructures have been synthesized primarily using vapor phase methods. Here, we present a simple wet chemical routine to synthesize heterostructures of PbTe/Te using Te nanowires as templates. A morphology evolution study for the formation of these heterostructures has been performed. On the basis of these control experiments, a pathway for the formation of these nanostructures is proposed. Reduction of a Pb precursor to Pb on Te nanowire templates followed by interdiffusion of Pb/Te leads to the formation of a thin shell of PbTe on the Te wires. Controlled dewetting of the thin shell leads to the formation of cube-shaped PbTe that is periodically arranged on the Te wires. Using control experiments, we show that different reactions parameters like rate of addition of the reducing agent, concentration of Pb precursor and thickness of initial Te nanowire play a critical role in controlling the spacing between the PbTe cubes on the Te wires. Using simple surface energy arguments, we propose a mechanism for the formation of the hybrid. The principles presented are general and can be exploited for the synthesis of other nanoscale heterostructures.

Multilayer out-of-plane overlap electrostatic energy harvesting structure actuated by blood pressure for powering intra-cardiac implants

NASA Astrophysics Data System (ADS)

Deterre, M.; Risquez, S.; Bouthaud, B.; Dal Molin, R.; Woytasik, M.; Lefeuvre, E.

2013-12-01

We present an innovative multilayer out-of-plane electrostatic energy harvesting device conceived in view of scavenging energy from regular blood pressure in the heart. This concept involves the use of a deformable packaging for the implant in order to transmit the blood pressure to the electrostatic transducer. As shown in previous work, this is possible by using thin metal micro-bellows structure, providing long term hermeticity and high flexibility. The design of the electrostatic device has overcome several challenges such as the very low frequency of the mechanical excitation (1 to 2 Hz) and the small available room in the medical implant. Analytical and numerical models have been used to maximize the capacitance variation, and hence to optimize the energy conversion. We have theoretically shown that a 25-layer transducer with 6-mm diameter and 1-mm thickness could harvest at least 20 mJ per heart beat in the left ventricle under a maximum voltage of 75 V. These results show that the proposed concept is promising and could power the next generation of leadless pacemakers.

Design, Fabrication and Levitation Experiments of a Micromachined Electrostatically Suspended Six-Axis Accelerometer

PubMed Central

Cui, Feng; Liu, Wu; Chen, Wenyuan; Zhang, Weiping; Wu, Xiaosheng

2011-01-01

A micromachined electrostatically suspended six-axis accelerometer, with a square plate as proof mass housed by a top stator and bottom stator, is presented. The device structure and related techniques concerning its operating principles, such as calculation of capacitances and electrostatic forces/moments, detection and levitation control of the proof mass, acceleration measurement, and structural parameters design, are described. Hybrid MEMS manufacturing techniques, including surface micromachining fabrication of thin film electrodes and interconnections, integration fabrication of thick nickel structures about 500 μm using UV-LIGA by successful removal of SU-8 photoresist mold, DRIE of silicon proof mass in thickness of 450 μm, microassembly and solder bonding, were employed to fabricate this prototype microdevice. A levitation experiment system for the fabricated microaccelerometer chip is introduced, and levitation results show that fast initial levitation within 10 ms and stable full suspension of the proof mass have been successfully demonstrated. PMID:22247662

Reliability of ultra-thin insulation coatings for long-term electrophysiological recordings

NASA Astrophysics Data System (ADS)

Hooker, S. A.

2006-03-01

Improved measurement of neural signals is needed for research into Alzheimer's, Parkinson's, epilepsy, strokes, and spinal cord injuries. At the heart of such instruments are microelectrodes that measure electrical signals in the body. Such electrodes must be small, stable, biocompatible, and robust. However, it is also important that they be easily implanted without causing substantial damage to surrounding tissue. Tissue damage can lead to the generation of immune responses that can interfere with the electrical measurement, preventing long-term recording. Recent advances in microfabrication and nanotechnology afford the opportunity to dramatically reduce the physical dimensions of recording electrodes, thereby minimizing insertion damage. However, one potential cause for concern is the reliability of the insulating coatings, applied to these ultra-fine-diameter wires to precisely control impedance. Such coatings are often polymeric and are applied everywhere but the sharpened tips of the wires, resulting in nominal impedances between 0.5 MOhms and 2.0 MOhms. However, during operation, the polymer degrades, changing the exposed area and the impedance. In this work, ultra-thin ceramic coatings were deposited as an alternative to polymer coatings. Processing conditions were varied to determine the effect of microstructure on measurement stability during two-electrode measurements in a standard buffer solution. Coatings were applied to seven different metals to determine any differences in performance due to the surface characteristics of the underlying wire. Sintering temperature and wire type had significant effects on coating degradation. Dielectric breakdown was also observed at relatively low voltages, indicating that test conditions must be carefully controlled to maximize reliability.

Carbon Nanotube/Space Durable Polymer Nanocomposite Films for Electrostatic Charge Dissipation

NASA Technical Reports Server (NTRS)

Smith, J. G., Jr.; Watson, K. A.; Thompson, C. M.; Connell, J. W.

2002-01-01

Low solar absorptivity, space environmentally stable polymeric materials possessing sufficient electrical conductivity for electrostatic charge dissipation (ESD) are of interest for potential applications on spacecraft as thin film membranes on antennas, solar sails, large lightweight space optics, and second surface mirrors. One method of imparting electrical conductivity while maintaining low solar absorptivity is through the use of single wall carbon nanotubes (SWNTs). However, SWNTs are difficult to disperse. Several preparative methods were employed to disperse SWNTs into the polymer matrix. Several examples possessed electrical conductivity sufficient for ESD. The chemistry, physical, and mechanical properties of the nanocomposite films will be presented.

Electrostatic Self-Assembly of Diamond Nanoparticles onto Al- and N-Polar Sputtered Aluminum Nitride Surfaces.

PubMed

Yoshikawa, Taro; Reusch, Markus; Zuerbig, Verena; Cimalla, Volker; Lee, Kee-Han; Kurzyp, Magdalena; Arnault, Jean-Charles; Nebel, Christoph E; Ambacher, Oliver; Lebedev, Vadim

2016-11-17

Electrostatic self-assembly of diamond nanoparticles (DNPs) onto substrate surfaces (so-called nanodiamond seeding) is a notable technique, enabling chemical vapor deposition (CVD) of nanocrystalline diamond thin films on non-diamond substrates. In this study, we examine this technique onto differently polarized (either Al- or N-polar) c -axis oriented sputtered aluminum nitride (AlN) film surfaces. This investigation shows that Al-polar films, as compared to N-polar ones, obtain DNPs with higher density and more homogeneously on their surfaces. The origin of these differences in density and homogeneity is discussed based on the hydrolysis behavior of AlN surfaces in aqueous suspensions.

Design and fabrication of a three-finger prosthetic hand using SMA muscle wires

NASA Astrophysics Data System (ADS)

Simone, Filomena; York, Alexander; Seelecke, Stefan

2015-03-01

Bio-inspired hand-like gripper systems based on shape memory alloy (SMA) wire actuation have the potential to enable a number of useful applications in, e.g., the biomedical field or industrial assembly systems. The inherent high energy density makes SMA solutions a natural choice for systems with lightweight, low noise and high force requirements, such as hand prostheses or robotic systems in a human/machine environment. The focus of this research is the development, design and realization of a SMA-actuated prosthetic hand prototype with three fingers. The use of thin wires (100 μm diameter) allows for high cooling rates and therefore fast movement of each finger. Grouping several small wires mechanically in parallel allows for high force actuation. To save space and to allow for a direct transmission of the motion to each finger, the SMA wires are attached directly within each finger, across each phalanx. In this way, the contraction of the wires will allow the movement of the fingers without the use of any additional gears. Within each finger, two different bundles of wires are mounted: protagonist ones that create bending movement and the antagonist ones that enable stretching of each phalanx. The resistance change in the SMA wires is measured during actuation, which allows for monitoring of the wire stroke and potentially the gripping force without the use of additional sensors. The hand is built with modern 3D-printing technologies and its performance while grasping objects of different size and shape is experimentally investigated illustrating the usefulness of the actuator concept.

Temperature Controlled Electrostatic Disorder and Polymorphism in Ultrathin Films of α-Sexithiophene

NASA Astrophysics Data System (ADS)

Hoffman, Benjamin; Jafari, Sara; McAfee, Terry; Apperson, Aubrey; O'Connor, Brendan; Dougherty, Daniel

Competing phases in well-ordered alpha-sexithiophene (α-6T) are shown to contribute to electrostatic disorder observed by differences in surface potential between mono- and bi-layer crystallites. Ultrathin films are of key importance to devices in which charge transport occurs in the first several monolayers nearest to a dielectric interface (e.g. thin film transistors) and complex structures in this regime impact the general electrostatic landscape. This study is comprised of 1.5 ML sample crystals grown via organic molecular beam deposition onto a temperature controlled hexamethyldisilazane (HMDS) passivated SiO2 substrate to produce well-ordered layer-by-layer type growth. Sample topography and surface potential were characterized simultaneously using Kelvin Probe Force Microscopy to then isolate contact potential differences by first and second layer α-6T regions. Films grown on 70° C, 120° C substrates are observed to have a bilayer with lower, higher potential than the monolayer, respectively. Resulting interlayer potential differences are a clear source of electrostatic disorder and are explained as subtle shifts in tilt-angles between layers relative to the substrate. These empirical results continue our understanding of how co-existing orientations contribute to the complex electrostatics influencing charge transport. NSF CAREER award DMR-1056861.

Basic study on hot-wire flow meter in forced flow of liquid hydrogen

NASA Astrophysics Data System (ADS)

Oura, Y.; Shirai, Y.; Shiotsu, M.; Murakami, K.; Tatsumoto, H.; Naruo, Y.; Nonaka, S.; Kobayashi, H.; Inatani, Y.; Narita, N.

2014-01-01

Liquid hydrogen (LH2) is a key issue in a carbon-free energy infrastructure at the energy storage and transportation stage. The typical features of LH2 are low viscosity, large latent heat and small density, compared with other general liquids. It is necessary to measure a mass flow of liquid hydrogen with a simple and compact method, especially in a two phase separate flow condition. We have proposed applying a hot-wire type flow meter, which is usually used a for gas flow meter, to LH2 flow due to the quite low viscosity and density. A test model of a compact LH2 hot-wire flow meter to measure local flow velocities near and around an inside perimeter of a horizontal tube by resistance thermometry was designed and made. The model flow meter consists of two thin heater wires made of manganin fixed in a 10 mm-diameter and 40 mm-length tube flow path made of GFRP. Each rigid heater wire was set twisted by 90 degrees from the inlet to the outlet along the inner wall. In other words, the wires were aslant with regard to the LH2 stream line. The heated wire was cooled by flowing LH2, and the flow velocity was obtained by means of the difference of the cooling characteristic in response to the flow velocity. In this report, we show results on the basic experiments with the model LH2 hot-wire flow meter. First, the heat transfer characteristics of the two heater wires for several LH2 flow velocities were measured. Second, the heating current was controlled to keep the wire temperature constant for various flow velocities. The relations between the flow velocity and the heating current were measured. The feasibility of the proposed model was confirmed.

Removal of Long-Lived Radon Daughters by Electropolishing Thin Layers of Stainless Steel

NASA Astrophysics Data System (ADS)

White, James; Schnee, Richard; Bunker, Raymond; Bowles, Michael; Cushman, Priscilla; Epland, Matthew; Pepin, Mark; Guiseppe, Vince

2012-10-01

Long-lived alpha and beta emitters in the Radon decay chain on detector surfaces may be limiting background in many experiments attempting to detect dark matter or neutrinoless double beta decay. To screen detector surfaces for this radioactive contamination, a low-radiation, multi-wire proportional chamber (the BetaCage) is under construction. Removal of Pb-210 implanted on its 25-micron stainless steel wires without causing significant variation in the diameter of the wires is critical to the BetaCage's ultimate sensitivity. An apparatus to perform electropolishing trials to remove roughly a micron of material has been assembled. These trials have shown promising results. Stainless steel square samples implanted with Pb-210 have shown counts with a reduction factor greater than 10 after electropolishing according to gamma assay. Furthermore, alpha counting has produced similar results, with a reduction factor greater than 100. Lastly, the diameters of wires after electropolishing have remained sufficiently uniform, with reduction in thickness consistent with expectations.

Orthogonal fluxgate mechanism operated with dc biased excitation

NASA Astrophysics Data System (ADS)

Sasada, I.

2002-05-01

A mode of operation is presented for an orthogonal fluxgate built with a thin magnetic wire. By adding a proper dc bias to the wire excitation, the new mode is easily established. In this case, the fundamental component of the induced voltage at the sensing coil (secondary voltage) is made sensitive to the axial magnetic field, compared to the second harmonic in a conventional orthogonal fluxgate. The operating principle is explained using a magnetization rotation model. A method is proposed to cancel the offset that is inevitable when the magnetic anisotropy is present in a magnetic wire at an angle to its circumference. Experimental results are shown for a sensor head consisting of a 2-cm-long Co-based amorphous wire 120 μm in diameter with a 220-turn sensing coil. The sensitivity obtained is higher than that obtained using a conventional type of the orthogonal fluxgate built with the same sensor head. It is also demonstrated that the proposed method for canceling the offset works well.

Electroless-plating technique for fabricating thin-wall convective heat-transfer models

NASA Technical Reports Server (NTRS)

Avery, D. E.; Ballard, G. K.; Wilson, M. L.

1984-01-01

A technique for fabricating uniform thin-wall metallic heat-transfer models and which simulates a Shuttle thermal protection system tile is described. Two 6- by 6- by 2.5-in. tiles were fabricated to obtain local heat transfer rates. The fabrication process is not limited to any particular geometry and results in a seamless thin-wall heat-transfer model which uses a one-wire thermocouple to obtain local cold-wall heat-transfer rates. The tile is relatively fragile because of the brittle nature of the material and the structural weakness of the flat-sided configuration; however, a method was developed and used for repairing a cracked tile.

Liquid-phase deposition of thin Si films by ballistic electro-reduction

NASA Astrophysics Data System (ADS)

Ohta, T.; Gelloz, B.; Kojima, A.; Koshida, N.

2013-01-01

It is shown that the nanocryatalline silicon ballistic electron emitter operates in a SiCl4 solution without using any counter electrodes and that thin amorphous Si films are efficiently deposited on the emitting surface with no contaminations and by-products. Despite the large electrochemical window of the SiCl4 solution, electrons injected with sufficiently high energies preferentially reduce Si4+ ions at the interface. Using an emitter with patterned line emission windows, a Si-wires array can be formed in parallel. This low-temperature liquid-phase deposition technique provides an alternative clean process for power-effective fabrication of advanced thin Si film structures and devices.

Cold-Drawn Bioabsorbable Ferrous and Ferrous Composite Wires: An Evaluation of Mechanical Strength and Fatigue Durability

NASA Astrophysics Data System (ADS)

Schaffer, Jeremy E.; Nauman, Eric A.; Stanciu, Lia A.

2012-08-01

Yield strengths exceeding 1 GPa with elastic strains exceeding 1 pct were measured in novel bioabsorbable wire materials comprising high-purity iron (Fe), manganese (Mn), magnesium (Mn), and zinc (Zn), which may enable the development of self-expandable, bioabsorbable, wire-based endovascular stents. The high strength of these materials is attributed to the fine microstructure and fiber textures achieved through cold drawing techniques. Bioabsorbable vascular stents comprising nutrient metal compositions may provide a means to overcome the limitations of polymer-based bioabsorbable stents such as excessive strut thickness and poor degradation rate control. Thin, 125- μm wires comprising combinations of ferrous alloys surrounding a relatively anodic nonferrous core were manufactured and tested using monotonic and cyclic techniques. The strength and durability properties are tested in air and in body temperature phosphate-buffered saline, and then they were compared with cold-drawn 316L stainless steel wire. The antiferromagnetic Fe35Mn-Mg composite wire exhibited more than 7 pct greater elasticity (1.12 pct vs 1.04 pct engineering strain), similar fatigue strength in air, an ultimate strength of more than 1.4 GPa, and a toughness exceeding 35 mJ/mm3 compared with 30 mJ/mm3 for 316L.

Temperature Diffusion Distribution of Electric Wire Deteriorated by Overcurrent

NASA Astrophysics Data System (ADS)

Choi, Chung-Seog; Kim, Hyang-Kon; Kim, Dong-Woo; Lee, Ki-Yeon

This study presents thermal diffusion distribution of the electric wires when overcurrent is supplied to copper wires. And then, this study intends to provide a basis of knowledge for analyzing the causes of electric accidents through hybrid technology. In the thermal image distribution analysis of the electric wire to which fusing current was supplied, it was found that less heat was accumulated in the thin wires because of easier heat dispersion, while more heat was accumulated in the thicker wires. The 3-dimensional thermal image analysis showed that heat distribution was concentrated at the center of the wire and the inclination of heat distribution was steep in the thicker wires. When 81A was supplied to 1.6mm copper wire for 500 seconds, the surface temperature of wire was maximum 46.68°C and minimum 30.87°C. It revealed the initial characteristics of insulation deterioration that generates white smoke without external deformation. In the analysis with stereoscopic microscope, the surface turned dark brown and rough with the increase of fusing current. Also, it was known that exfoliation occurred when wire melted down with 2 times the fusing current. With the increase of current, we found the number of primary arms of the dendrite structure to be increased and those of the secondary and tertiary arms to be decreased. Also, when the overcurrent reached twice the fusing current, it was found that columnar composition, observed in the cross sectional structure of molten wire, appeared and formed regular directivity. As described above, we could present the burning pattern and change in characteristics of insulation and conductor quantitatively. And we could not only minimize the analysis error by combining the information but also present the scientific basis in the analysis of causes of electric accidents, mediation of disputes on product liability concerning the electric products.

Application of Rapid Prototyping and Wire Arc Spray to the Fabrication of Injection Mold Tools (MSFC Center Director's Discretionary Fund)

NASA Technical Reports Server (NTRS)

Cooper, K. G.

2000-01-01

Rapid prototyping (RP) is a layer-by-layer-based additive manufacturing process for constructing three-dimensional representations of a computer design from a wax, plastic, or similar material. Wire arc spray (WAS) is a metal spray forming technique, which deposits thin layers of metal onto a substrate or pattern. Marshall Space Flight Center currently has both capabilities in-house, and this project proposed merging the two processes into an innovative manufacturing technique, in which intermediate injection molding tool halves were to be fabricated with RP and WAS metal forming.

Unconventional Current Scaling and Edge Effects for Charge Transport through Molecular Clusters

PubMed Central

2017-01-01

Metal–molecule–metal junctions are the key components of molecular electronics circuits. Gaining a microscopic understanding of their conducting properties is central to advancing the field. In the present contribution, we highlight the fundamental differences between single-molecule and ensemble junctions focusing on the fundamentals of transport through molecular clusters. In this way, we elucidate the collective behavior of parallel molecular wires, bridging the gap between single molecule and large-area monolayer electronics, where even in the latter case transport is usually dominated by finite-size islands. On the basis of first-principles charge-transport simulations, we explain why the scaling of the conductivity of a junction has to be distinctly nonlinear in the number of molecules it contains. Moreover, transport through molecular clusters is found to be highly inhomogeneous with pronounced edge effects determined by molecules in locally different electrostatic environments. These effects are most pronounced for comparably small clusters, but electrostatic considerations show that they prevail also for more extended systems. PMID:29043825

Experimental plasma studies

NASA Technical Reports Server (NTRS)

Dunn, M. G.

1972-01-01

The rate coefficients for the reactions C(+) + e(-) + e(-) yields C + e(-) and CO(+) + e(-) yields C + O were measured over the electron temperature range of approximately 1500 deg K to 7000 deg K. The measurements were performed in CO that had expanded from equilibrium reservoir conditions of 7060 deg K at 17.3 atm pressure and from 6260 deg K at 10.0 atm pressure. Two RAM flight probes were used to measure electron density and electron temperature in the expanding flow of a shock tunnel. Experiments were performed in the inviscid flow with both probes and in the nozzle-wall boundary layer with the constant bias-voltage probe. The distributions of electron density and electron temperature were independently measured using voltage-swept thin-wire probes. Thin-wire Langmuir probes were also used to measure the electron-density and electron-temperature distributions in the boundary layer of a sharp flat plate located on the nozzle centerline. Admittance measurements were performed with the RAM C and RAM C-C S-band antennas in the presence of an ionized boundary layer.

Removal of long-lived 222Rn daughters by electropolishing thin layers of stainless steel

NASA Astrophysics Data System (ADS)

Schnee, R. W.; Bowles, M. A.; Bunker, R.; McCabe, K.; White, J.; Cushman, P.; Pepin, M.; Guiseppe, V. E.

2013-08-01

Long-lived alpha and beta emitters in the 222Rn decay chain on detector surfaces may be the limiting background in many experiments attempting to detect dark matter or neutrinoless double beta decay. Removal of tens of microns of material via electropolishing has been shown to be effective at removing radon daughters implanted into material surfaces. Some applications, however, require the removal of uniform and significantly smaller thicknesses. Here, we demonstrate that electropolishing < 1 μm from stainless-steel plates reduces the contamination efficiently, by a factor > 100. Examination of electropolished wires with a scanning electron microscope confirms that the thickness removed is reproducible and reasonably uniform. Together, these tests demonstrate the effectiveness of removal of radon daughters for a proposed low-radiation, multi-wire proportional chamber (the BetaCage), without compromising the screener's energy resolution. More generally, electropolishing thin layers of stainless steel may effectively remove radon daughters without compromising precision-machined parts.

Removal of long-lived {sup 222}Rn daughters by electropolishing thin layers of stainless steel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schnee, R. W.; Bowles, M. A.; Bunker, R.

Long-lived alpha and beta emitters in the {sup 222}Rn decay chain on detector surfaces may be the limiting background in many experiments attempting to detect dark matter or neutrinoless double beta decay. Removal of tens of microns of material via electropolishing has been shown to be effective at removing radon daughters implanted into material surfaces. Some applications, however, require the removal of uniform and significantly smaller thicknesses. Here, we demonstrate that electropolishing < 1 μm from stainless-steel plates reduces the contamination efficiently, by a factor > 100. Examination of electropolished wires with a scanning electron microscope confirms that the thicknessmore » removed is reproducible and reasonably uniform. Together, these tests demonstrate the effectiveness of removal of radon daughters for a proposed low-radiation, multi-wire proportional chamber (the BetaCage), without compromising the screener’s energy resolution. More generally, electropolishing thin layers of stainless steel may effectively remove radon daughters without compromising precision-machined parts.« less

Magnesium Diboride Current Leads

NASA Technical Reports Server (NTRS)

Panek, John

2010-01-01

A recently discovered superconductor, magnesium diboride (MgB2), can be used to fabricate conducting leads used in cryogenic applications. Dis covered to be superconducting in 2001, MgB2 has the advantage of remaining superconducting at higher temperatures than the previously used material, NbTi. The purpose of these leads is to provide 2 A of electricity to motors located in a 1.3 K environment. The providing environment is a relatively warm 17 K. Requirements for these leads are to survive temperature fluctuations in the 5 K and 11 K heat sinks, and not conduct excessive heat into the 1.3 K environment. Test data showed that each lead in the assembly could conduct 5 A at 4 K, which, when scaled to 17 K, still provided more than the required 2 A. The lead assembly consists of 12 steelclad MgB2 wires, a tensioned Kevlar support, a thermal heat sink interface at 4 K, and base plates. The wires are soldered to heavy copper leads at the 17 K end, and to thin copper-clad NbTi leads at the 1.3 K end. The leads were designed, fabricated, and tested at the Forschungszentrum Karlsruhe - Institut foer Technische Physik before inclusion in Goddard's XRS (X-Ray Spectrometer) instrument onboard the Astro-E2 spacecraft. A key factor is that MgB2 remains superconducting up to 30 K, which means that it does not introduce joule heating as a resistive wire would. Because the required temperature ranges are 1.3-17 K, this provides a large margin of safety. Previous designs lost superconductivity at around 8 K. The disadvantage to MgB2 is that it is a brittle ceramic, and making thin wires from it is challenging. The solution was to encase the leads in thin steel tubes for strength. Previous designs were so brittle as to risk instrument survival. MgB2 leads can be used in any cryogenic application where small currents need to be conducted at below 30 K. Because previous designs would superconduct only at up to 8 K, this new design would be ideal for the 8-30 K range.

The effects of return current and target charging in short pulse high intensity laser interactions

NASA Astrophysics Data System (ADS)

Beg, Farhat

2003-10-01

Since the introduction of the technique of chirped pulse amplification (CPA), peak laser intensities have increased dramatically. It is now possible to perform laser-plasma interaction experiments at intensities approaching 1021 Wcm-2. The electrons in the field of such lasers are highly relativistic (gamma 31) and the temperature of the hot electron distribution produced in a plasma at such extreme intensities can exceed 10 MeV. Since the resulting beam current exceeds the Alfvén limit, a neutralizing return current of cold plasma electrons moving in the opposite direction is produced. Another source of return current is that due to the escape of very energetic electrons from the target, which then creates a large electrostatic potential due to charge separation. These return currents can cause significant ohmic heating. We present results from experiments performed at Rutherford Appleton Laboratory using the VULCAN laser facility (I> 5 x1019 Wcm-2). Single wire targets were used and in some shots a secondary wire or foil was placed near the target. Three main observations were made: (i) generation of a Z-pinch in the wire due to the return current, (ii) optical transition radiation at 2w and (iii) proton emission from both the primary wire target and the secondary wire or foil. The Z-pinch was observed to be m=0 unstable. The current was estimated to be about 0.8 MA using simple energy balance considerations. Intense second harmonic emission due to coherent optical transition radiation from both the primary target and secondary objects was observed and is likely due to electron bunches accelerated by the ponderomotive jxB force of the laser. The proton emission from the secondary wire or foil was likely due to field emission of electrons from the these objects in response to the large potential produced from charging of the primary target. Results of simulations to model these interactions will also be presented.

The Integrity bare-metal stent made by continuous sinusoid technology.

PubMed

Turco, Mark A

2011-05-01

The Integrity Coronary Stent System (Medtronic Vascular, CA, USA) is a low-profile, open-cell, cobalt-chromium-alloy advanced bare-metal iteration of the well-known Driver/Micro-Driver Coronary Stent System (Medtronic Vascular). The Integrity stent is made with a process called continuous sinusoid technology. This process allows stent construction via wrapping a single thin strand of wire around a mandrel in a sinusoid configuration, with laser fusion of adjacent crowns. The wire-forming process and fusion pattern provide the stent with a continuous preferential bending plane, intended to allow easier access to, and smoother tracking within, distal and tortuous vessels while radial strength is maintained. Continuous sinusoid technology represents innovation in the design of stent platforms and will provide a future stent platform for newer technology, including drug-eluting stent platforms, drug-filled stents and core wire stents.

A haptic device for guide wire in interventional radiology procedures.

PubMed

Moix, Thomas; Ilic, Dejan; Bleuler, Hannes; Zoethout, Jurjen

2006-01-01

Interventional Radiology (IR) is a minimally invasive procedure where thin tubular instruments, guide wires and catheters, are steered through the patient's vascular system under X-ray imaging. In order to perform these procedures, a radiologist has to be trained to master hand-eye coordination, instrument manipulation and procedure protocols. The existing simulation systems all have major drawbacks: the use of modified instruments, unrealistic insertion lengths, high inertia of the haptic device that creates a noticeably degraded dynamic behavior or excessive friction that is not properly compensated for. In this paper we propose a quality training environment dedicated to IR. The system is composed of a virtual reality (VR) simulation of the patient's anatomy linked to a robotic interface providing haptic force feedback. This paper focuses on the requirements, design and prototyping of a specific haptic interface for guide wires.

Nanocube-based hematite photoanode produced in the presence of Na2HPO4 for efficient solar water splitting

NASA Astrophysics Data System (ADS)

Liu, Kan; Wang, Hongyan; Wu, Quanping; Zhao, Jun; Sun, Zhe; Xue, Song

2015-06-01

A thin film of α-Fe2O3 on FTO substrate has been synthesized from hydrothermal process in an aqueous solution of FeCl3 and Na2HPO4. A nanocube structure of α-Fe2O3 is observed within the formed hematite films and coated with phosphate ions on the surface. For comparison, another phosphate modified hematite film has been prepared by soaking the bare hematite film in Na2HPO4 solution. A negative electrostatic field can be built up on the surface of both phosphate modified hematite which will promote charge separation and extraction of photoexcited holes to the electrode surface. It is found that different types of phosphate complex exist in the hematite films, which has been determined by the isoelectric point (IEP) of the hematite films, and consequently influences the formation and strength of the electrostatic field. The effects of phosphate ions on the morphology, surface characteristics and the photoelectrochemical properties of the hematite thin films are investigated and the mechanism is proposed.

Nanoscale Investigation of Grain Growth in RF-Sputtered Indium Tin Oxide Thin Films by Scanning Probe Microscopy

NASA Astrophysics Data System (ADS)

Lamsal, B. S.; Dubey, M.; Swaminathan, V.; Huh, Y.; Galipeau, D.; Qiao, Q.; Fan, Q. H.

2014-11-01

This work studied the electronic characteristics of the grains and grain boundaries of indium tin oxide (ITO) thin films using electrostatic and Kelvin probe force microscopy. Two types of ITO films were compared, deposited using radiofrequency magnetron sputtering in pure argon or 99% argon + 1% oxygen, respectively. The average grain size and surface roughness increased with substrate temperature for the films deposited in pure argon. With the addition of 1% oxygen, the increase in the grain size was inhibited above 150°C, which was suggested to be due to passivation of the grains by the excess oxygen. Electrostatic force microscopy and Kelvin probe force microscopy (KPFM) images confirmed that the grain growth was defect mediated and occurred at defective interfaces at high temperatures. Films deposited at room temperature with 1% oxygen showed crystalline nature, while films deposited with pure argon at room temperature were amorphous as observed from KPFM images. The potential drop across the grain and grain boundary was determined by taking surface potential line profiles to evaluate the electronic properties.

Anomalous columnar order of charged colloidal platelets

NASA Astrophysics Data System (ADS)

Morales-Anda, L.; Wensink, H. H.; Galindo, A.; Gil-Villegas, A.

2012-01-01

Monte Carlo computer simulations are carried out for a model system of like-charged colloidal platelets in the isothermal-isobaric ensemble (NpT). The aim is to elucidate the role of electrostatic interactions on the structure of synthetic clay systems at high particle densities. Short-range repulsions between particles are described by a suitable hard-core model representing a discotic particle. This potential is supplemented with an electrostatic potential based on a Yukawa model for the screened Coulombic potential between infinitely thin disklike macro-ions. The particle aspect-ratio and electrostatic parameters were chosen to mimic an aqueous dispersion of thin, like-charged, rigid colloidal platelets at finite salt concentration. An examination of the fluid phase diagram reveals a marked shift in the isotropic-nematic transition compared to the hard cut-sphere reference system. Several statistical functions, such as the pair correlation function for the center-of-mass coordinates and structure factor, are obtained to characterize the structural organization of the platelets phases. At low salinity and high osmotic pressure we observe anomalous hexagonal columnar structures characterized by interpenetrating columns with a typical intercolumnar distance corresponding to about half of that of a regular columnar phase. Increasing the ionic strength leads to the formation of glassy, disordered structures consisting of compact clusters of platelets stacked into finite-sized columns. These so-called "nematic columnar" structures have been recently observed in systems of charge-stabilized gibbsite platelets. Our findings are corroborated by an analysis of the static structure factor from a simple density functional theory.

High-throughput screening for combinatorial thin-film library of thermoelectric materials.

PubMed

Watanabe, Masaki; Kita, Takuji; Fukumura, Tomoteru; Ohtomo, Akira; Ueno, Kazunori; Kawasaki, Masashi

2008-01-01

A high-throughput method has been developed to evaluate the Seebeck coefficient and electrical resistivity of combinatorial thin-film libraries of thermoelectric materials from room temperature to 673 K. Thin-film samples several millimeters in size were deposited on an integrated Al2O3 substrate with embedded lead wires and local heaters for measurement of the thermopower under a controlled temperature gradient. An infrared camera was used for real-time observation of the temperature difference Delta T between two electrical contacts on the sample to obtain the Seebeck coefficient. The Seebeck coefficient and electrical resistivity of constantan thin films were shown to be almost identical to standard data for bulk constantan. High-throughput screening was demonstrated for a thermoelectric Mg-Si-Ge combinatorial library.

Characterization of the Li beam probe with a beam profile monitor on JETa)

NASA Astrophysics Data System (ADS)

Nedzelskiy, I. S.; Korotkov, A.; Brix, M.; Morgan, P.; Vince, J.; Jet Efda Contributors

2010-10-01

The lithium beam probe (LBP) is widely used for measurements of the electron density in the edge plasma of magnetically confined fusion experiments. The quality of LBP data strongly depends on the stability and profile shape of the beam. The main beam parameters are as follows: beam energy, beam intensity, beam profile, beam divergence, and the neutralization efficiency. For improved monitoring of the beam parameters, a beam profile monitor (BPM) from the National Electrostatics Corporation (NEC) has been installed in the Li beam line at JET. In the NEC BPM, a single grounded wire formed into a 45° segment of a helix is rotated by a motor about the axis of the helix. During each full revolution, the wire sweeps twice across the beam to give X and Y profiles. In this paper, we will describe the properties of the JET Li beam as measured with the BPM and demonstrate that it facilitates rapid optimization of the gun performance.

Complex coacervate-based materials for biomedicine.

PubMed

Blocher, Whitney C; Perry, Sarah L

2017-07-01

There has been increasing interest in complex coacervates for deriving and transporting biomaterials. Complex coacervates are a dense, polyelectrolyte-rich liquid that results from the electrostatic complexation of oppositely charged macroions. Coacervates have long been used as a strategy for encapsulation, particularly in food and personal care products. More recent efforts have focused on the utility of this class of materials for the encapsulation of small molecules, proteins, RNA, DNA, and other biomaterials for applications ranging from sensing to biomedicine. Furthermore, coacervate-related materials have found utility in other areas of biomedicine, including cartilage mimics, tissue culture scaffolds, and adhesives for wet, biological environments. Here, we discuss the self-assembly of complex coacervate-based materials, current challenges in the intelligent design of these materials, and their utility applications in the broad field of biomedicine. WIREs Nanomed Nanobiotechnol 2017, 9:e1442. doi: 10.1002/wnan.1442 For further resources related to this article, please visit the WIREs website. © 2016 Wiley Periodicals, Inc.

Fluid Physics

NASA Image and Video Library

2003-01-19

Expedition 6 astronaut Dr. Don Pettit photographed a cube shaped wire frame supporting a thin film made from a water-soap solution during his Saturday Morning Science aboard the International Space Station’s (ISS) Destiny Laboratory. Food coloring was added to several faces to observe the effects of diffusion within the film.

Electric-field-driven phase transition in vanadium dioxide

NASA Astrophysics Data System (ADS)

Wu, B.; Zimmers, A.; Aubin, H.; Ghosh, R.; Liu, Y.; Lopez, R.

2011-12-01

We report on local probe measurements of current-voltage and electrostatic force-voltage characteristics of electric-field-induced insulator to metal transition in VO2 thin film. In conducting AFM mode, switching from the insulating to metallic state occurs for electric-field threshold E˜6.5×107Vm-1 at 300K. Upon lifting the tip above the sample surface, we find that the transition can also be observed through a change in electrostatic force and in tunneling current. In this noncontact regime, the transition is characterized by random telegraphic noise. These results show that electric field alone is sufficient to induce the transition; however, the electronic current provides a positive feedback effect that amplifies the phenomena.

Electrostatic Self-Assembly of Diamond Nanoparticles onto Al- and N-Polar Sputtered Aluminum Nitride Surfaces

PubMed Central

Yoshikawa, Taro; Reusch, Markus; Zuerbig, Verena; Cimalla, Volker; Lee, Kee-Han; Kurzyp, Magdalena; Arnault, Jean-Charles; Nebel, Christoph E.; Ambacher, Oliver; Lebedev, Vadim

2016-01-01

Electrostatic self-assembly of diamond nanoparticles (DNPs) onto substrate surfaces (so-called nanodiamond seeding) is a notable technique, enabling chemical vapor deposition (CVD) of nanocrystalline diamond thin films on non-diamond substrates. In this study, we examine this technique onto differently polarized (either Al- or N-polar) c-axis oriented sputtered aluminum nitride (AlN) film surfaces. This investigation shows that Al-polar films, as compared to N-polar ones, obtain DNPs with higher density and more homogeneously on their surfaces. The origin of these differences in density and homogeneity is discussed based on the hydrolysis behavior of AlN surfaces in aqueous suspensions. PMID:28335345

Analytical and numerical modeling of an axisymmetrical electrostatic transducer with interior geometrical discontinuity.

PubMed

Honzík, Petr; Podkovskiy, Alexey; Durand, Stéphane; Joly, Nicolas; Bruneau, Michel

2013-11-01

The main purpose of the paper is to contribute at presenting an analytical and a numerical modeling which would be relevant for interpreting the couplings between a circular membrane, a peripheral cavity having the same external radius as the membrane, and a thin air gap (with a geometrical discontinuity between them), and then to characterize small scale electrostatic receivers and to propose procedures that could be suitable for fitting adjustable parameters to achieve optimal behavior in terms of sensitivity and bandwidth expected. Therefore, comparison between these theoretical methods and characterization of several shapes is dealt with, which show that the models would be appropriate to address the design of such transducers.

High-Temperature, Thin-Film Strain Gages Improved

NASA Technical Reports Server (NTRS)

2005-01-01

Conventional resistance strain gage technology uses "bonded" strain gages. These foil or wire gages are bonded onto the surface of the test article with glue, ceramic cements, or flame-sprayed ceramics. These bonding agents can, in some instances, limit both the degree of strain transmission from the test structure to the gage and the maximum working temperature of the gage. Also, the bulky, bonded gage normally disrupts aerodynamic gas flow on the surface of the test structure because of its intrusive character. To respond to the urgent needs in aeronautic and aerospace research where stress and temperature gradients are high, aerodynamic effects need to be minimized, and higher operational temperatures are required, the NASA Lewis Research Center developed a thin film strain gage. This gage, a vacuum-deposited thin film formed directly on the surface of a test structure, operates at much higher temperatures than commercially available gages do and with minimal disruption of the aerodynamic flow. The gage uses an alloy, palladium-13 wt % chromium (hereafter, PdCr), which was developed by United Technologies Research Center under a NASA contract. PdCr is structurally stable and oxidation resistant up to at least 1100 C (2000 F); its temperature-induced resistance change is linear, repeatable, and not sensitive to the rates of heating and cooling. An early strain gage, which was made of 25-micrometer-diameter PdCr wire and demonstrated to be useable to 800 C, won an R&D 100 award in 1991. By further improving the purity of the material and by developing gage fabrication techniques that use sputter-deposition, photolithography patterning, and chemical etching, we have made an 8- to 10-m PdCr thin-film strain gage that can measure dynamic and static strain to at least 1100 C. For static strain measurements, a 5-m-thick Pt element serves as a temperature compensator to further minimize the temperature effect of the gage. These thin-film gages provide the advantage of minimally intrusive surface strain measurements and give highly repeatable readings with low drift at temperatures from ambient to 1100 C. This is a 300 C advance in operating temperature over the PdCr wire gage and a 500 C advance over commercially available gages made of other materials.

Functionalized bioinspired microstructured optical fiber pores for applications in chemical vapor sensing

NASA Astrophysics Data System (ADS)

Calkins, Jacob A.

Chemical vapor sensing for defense, homeland security, environmental, and agricultural application is a challenge, which due combined requirements of ppt sensitivity, high selectivity, and rapid response, cannot be met using conventional analytical chemistry techniques. New sensing approaches and platforms are necessary in order to make progress in this rapidly evolving field. Inspired by the functionalized nanopores on moth sensilla hairs that contribute to the high selectivity and sensitivity of this biological system, a chemical vapor sensor based on the micro to nanoscale pores in microstructured optical fibers (MOFs) was designed. This MOF based chemical vapor sensor design utilizes MOF pores functionalized with organic self-assembled monolayers (SAMs) for selectivity and separations and a gold plasmonic sensor for detection and discrimination. Thin well-controlled gold films in MOF pores are critical components for the fabrication of structured plasmonic chemical vapor sensors. Thermal decomposition of dimethyl Au(II) trifluoroacetylacetonate dissolved in near-critical CO2 was used to deposit gold island films within the MOF pores. Using a 3mercatopropyltrimethoxysilane adhesion layer, continuous gold thin films as thin as 20--30 nm were deposited within MOF pores as small as 500 nm in diameter. The gold island films proved to be SERS active and were used to detect 900 ppt 2,4 DNT vapor in high pressure nitrogen and 6 ppm benzaldehyde. MOF based waveguide Raman (WGR), which can probe the air/silica interface between a waveguiding core and surrounding pores, was developed to detect and characterize SAMs and other thin films deposited in micro to nanoscale MOF pores. MOF based WGR was used to characterize an octadecyltrichlorosilane (OTS) SAM deposited in 1.6 mum diameter pores iv to demonstrate that the SAM was well-formed, uniform along the pore length, and only a single layer. MOF based WGR was used to detect a human serum albumin monolayer deposited on the OTS SAM and monitor in-situ the combustion of an OTS SAM in high pressure oxygen. Light scattering, an optical characterization technique that provides ellipsometric data from micro to nanoscale cylinders, was developed in order to characterize highly smooth wires and MOF pores. Clean, bare gold wires etched from MOF pore templates were found to have angle dependent Psi and Delta values that agree with numerically calculated and finite element modeled values over the full angular 340° collection range. Light scattering was shown to be sensitive to ellipticities in the cross-section of silica, gold, and silicon wires down to 1%. Using alkanethiol SAMs deposited on gold wires, light scattering was demonstrated to be able to detect films as thin as 1.5 nm, and able to distinguish between a decanethiol (1.5 nm) and an octadecanethiol SAM (2.7 mn). The high sensitivity of light scattering will allow it to characterize SAMs and thin films on the inner surfaces of MOF pores. WGR and light scattering provide the analytical tools that will allow for the further development of organic SAMs and thin films within MOF pores for analyte selectivity and chromatographic separations. This high selectivity combined with the sensitivity of a 3-dimensional nanostructured gold plasmonic sensor allows for the fabrication of a chemical vapor sensor inspired by the field performance of moth sensilla hairs.

Hydrogen in thin Pd-based layers deposited on reticulated vitreous carbon-A new system for electrochemical capacitors

NASA Astrophysics Data System (ADS)

Łukaszewski, M.; Żurowski, A.; Czerwiński, A.

Reticulated vitreous carbon (RVC) has been used as a matrix for electrodeposition of thin layers of Pd and Pd-rich Pd-Rh alloys. It was found that RVC substrate does not affect qualitatively hydrogen absorption behavior of Pd-based deposits. Similarly to thin Pd or Pd alloy layers deposited on Au wires, the α-β phase transition controls the overall rate of hydrogen absorption and desorption into/from Pd-based/RVC electrodes. The possibility of the application of these materials as phase charging-discharging systems was investigated. The values of specific pseudocapacitance, specific power and specific energy were comparable with those for supercapacitors utilizing various redox reactions.

Electrostatic adhesion for added functionality of composite structures

NASA Astrophysics Data System (ADS)

Heath, Callum J. C.; Bond, Ian P.; Potter, Kevin D.

2016-02-01

Electrostatic adhesion can be used as a means of reversible attachment. The incorporation of electrostatic adhesion into fibre reinforced polymer (FRP) composite structures could provide significant value added functionality. Imparting large potential differences (˜2 kV) across electrodes generates an attractive force, thus providing a means of attachment. This could be used as a reversible latching mechanism or as a means of controllable internal connectivity. Varying the connectivity for discrete elements of a substructure of a given design allows for control of internal load paths and moment of area of the cross section. This could facilitate variable stiffness (both in bending and torsion). Using a combination of existing fabrication techniques, functional electrodes have been integrated within a FRP. Copper polyimide thin film laminate material has been both co-cured with carbon fibre reinforced epoxy and bonded to PVC closed cell foam core material to provide a range of structural configurations with integrated electrodes. The ability of such integrated devices to confer variations in global bending stiffness of basic beam structures is investigated. Through the application of 4 kV across integrated electrostatic adhesive devices, a 112% increase in flexural stiffness has been demonstrated for a composite sandwich structure.

Nanoscale patterning of electronic devices at the amorphous LaAlO3/SrTiO3 oxide interface using an electron sensitive polymer mask

NASA Astrophysics Data System (ADS)

Bjørlig, Anders V.; von Soosten, Merlin; Erlandsen, Ricci; Dahm, Rasmus Tindal; Zhang, Yu; Gan, Yulin; Chen, Yunzhong; Pryds, Nini; Jespersen, Thomas S.

2018-04-01

A simple approach is presented for designing complex oxide mesoscopic electronic devices based on the conducting interfaces of room temperature grown LaAlO3/SrTiO3 heterostructures. The technique is based entirely on methods known from conventional semiconductor processing technology, and we demonstrate a lateral resolution of ˜100 nm. We study the low temperature transport properties of nanoscale wires and demonstrate the feasibility of the technique for defining in-plane gates allowing local control of the electrostatic environment in mesoscopic devices.

ESD testing of the 8S actuator (u)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mchugh, Douglas C

2010-12-03

The 8S actuator is a hot-wire initiated explosive component used to drive the W76-1 2X Acorn 1V valve. It is known to be safe from human electrostatic discharge (ESD) pin-to-pin and all pin-to-cup stimuli as well as 1 amp/1 watt safe. However low impedance (furniture) ESD stimuli applied pin-to-pin has not been evaluated. Components were tested and the results analyzed. The 8S actuator has been shown to be immune to human and severe furniture ESD, whether applied pin-to-pin or pin-to-cup.

Compliant layer chucking surface

DOEpatents

Blaedel, Kenneth L [Dublin, CA; Spence, Paul A [Pleasanton, CA; Thompson, Samuel L [Pleasanton, CA

2004-12-28

A method and apparatus are described wherein a thin layer of complaint material is deposited on the surface of a chuck to mitigate the deformation that an entrapped particle might cause in the part, such as a mask or a wafer, that is clamped to the chuck. The harder particle will embed into the softer layer as the clamping pressure is applied. The material composing the thin layer could be a metal or a polymer for vacuum or electrostatic chucks. It may be deposited in various patterns to affect an interrupted surface, such as that of a "pin" chuck, thereby reducing the probability of entrapping a particle.

A thin film nitinol heart valve.

PubMed

Stepan, Lenka L; Levi, Daniel S; Carman, Gregory P

2005-11-01

In order to create a less thrombogenic heart valve with improved longevity, a prosthetic heart valve was developed using thin film nitinol (NiTi). A "butterfly" valve was constructed using a single, elliptical piece of thin film NiTi and a scaffold made from Teflon tubing and NiTi wire. Flow tests and pressure readings across the valve were performed in vitro in a pulsatile flow loop. Bio-corrosion experiments were conducted on untreated and passivated thin film nitinol. To determine the material's in vivo biocompatibility, thin film nitinol was implanted in pigs using stents covered with thin film NiTi. Flow rates and pressure tracings across the valve were comparable to those through a commercially available 19 mm Perimount Edwards tissue valve. No signs of corrosion were present on thin film nitinol samples after immersion in Hank's solution for one month. Finally, organ and tissue samples explanted from four pigs at 2, 3, 4, and 6 weeks after thin film NiTi implantation appeared without disease, and the thin film nitinol itself was without thrombus formation. Although long term testing is still necessary, thin film NiTi may be very well suited for use in artificial heart valves.

Electrostatic modification of novel materials

NASA Astrophysics Data System (ADS)

Ahn, C. H.; Bhattacharya, A.; di Ventra, M.; Eckstein, J. N.; Frisbie, C. Daniel; Gershenson, M. E.; Goldman, A. M.; Inoue, I. H.; Mannhart, J.; Millis, Andrew J.; Morpurgo, Alberto F.; Natelson, Douglas; Triscone, Jean-Marc

2006-10-01

Application of the field-effect transistor principle to novel materials to achieve electrostatic doping is a relatively new research area. It may provide the opportunity to bring about modifications of the electronic and magnetic properties of materials through controlled and reversible changes of the carrier concentration without modifying the level of disorder, as occurs when chemical composition is altered. As well as providing a basis for new devices, electrostatic doping can in principle serve as a tool for studying quantum critical behavior, by permitting the ground state of a system to be tuned in a controlled fashion. In this paper progress in electrostatic doping of a number of materials systems is reviewed. These include structures containing complex oxides, such as cuprate superconductors and colossal magnetoresistive compounds, organic semiconductors, in the form of both single crystals and thin films, inorganic layered compounds, single molecules, and magnetic semiconductors. Recent progress in the field is discussed, including enabling experiments and technologies, open scientific issues and challenges, and future research opportunities. For many of the materials considered, some of the results can be anticipated by combining knowledge of macroscopic or bulk properties and the understanding of the field-effect configuration developed during the course of the evolution of conventional microelectronics. However, because electrostatic doping is an interfacial phenomenon, which is largely an unexplored field, real progress will depend on the development of a better understanding of lattice distortion and charge transfer at interfaces in these systems.

A novel electrostatic dry powder coating process for pharmaceutical dosage forms: immediate release coatings for tablets.

PubMed

Qiao, Mingxi; Zhang, Liqiang; Ma, Yingliang; Zhu, Jesse; Chow, Kwok

2010-10-01

An electrostatic dry powder coating process for pharmaceutical solid dosage forms was developed for the first time by electrostatic dry powder coating in a pan coater system. Two immediate release coating compositions with Opadry® AMB and Eudragit® EPO were successfully applied using this process. A liquid plasticizer was sprayed onto the surface of the tablet cores to increase the conductivity of tablet cores to enhance particle deposition, electrical resistivity reduced from greater than 1×10(13)Ωm to less than 1×10(9)Ωm, and to lower the glass transition temperature (T(g)) of the coating polymer for film forming in the pan coater. The application of liquid plasticizer was followed by spraying charged coating particles using an electrostatic charging gun to enhance the uniform deposition on tablet surface. The coating particles were coalesced into a thin film by curing at an acceptable processing temperature as formation was confirmed by SEM micrographs. The results also show that the optimized dry powder coating process produces tablets with smooth surface, good coating uniformity and release profile that are comparable to that of the tablet cores. The data also suggest that this novel electrostatic dry powder coating technique is an alternative to aqueous- or solvent-based coating process for pharmaceutical products. Crown Copyright © 2010. Published by Elsevier B.V. All rights reserved.

Heating in short-pulse laser-driven cone-capped wire targets

NASA Astrophysics Data System (ADS)

Mason, R. J.; Wei, M.; King, J.; Beg, F.; Stephens, R. B.

2007-11-01

The 2-D implicit hybrid simulation code e-PLAS has been used to study heating in cone-capped copper wire targets. The code e-PLAS tracks collisional particle-in-cell (PIC) electrons traversing background plasma of collisional Eulerian cold electron and ion fluids. It computes E- and B-fields by the Implicit Moment Method [1,2]. In recent experiments [3] at the Vulcan laser facility, sub- picosecond laser pulses at 1.06 μm, and 4.0 x 10^20 W/cm^2 intensity were focused into thin-walled (˜10 μm) cones attached to copper wires. The wire diameter was varied from 10-40 μm with a typical length of 1 mm. We characterize heating of the wires as a function of their diameters and length, and relate modifications of this heating to changes in the assumed laser-generated hot electron spectrum and directivity. As in recent nail experiments [4], the cones can serve as reservoirs for hot electrons, diverting them from passage down the wires. [1] R. J. Mason, and C. Cranfill, IEEE Trans. Plasma Sci. PS-14, 45 (1986). [2] R. J. Mason, J. Comp. Phys. 71, 429 (1987). [3] J. King et al., to be submitted to Phys. Rev. Lett.. [4] R. J. Mason, M. Wei, F. Beg, R. Stephens, and C. Snell, in Proc. of ICOPS07, Albuquerque, NM, June 17-22, 2007, Talk 7D4.

Millimeter Thin and Rubber-Like Solid-State Lighting Modules Fabricated Using Roll-to-Roll Fluidic Self-Assembly and Lamination.

PubMed

Park, Se-Chul; Biswas, Shantonu; Fang, Jun; Mozafari, Mahsa; Stauden, Thomas; Jacobs, Heiko O

2015-06-24

A millimeter thin rubber-like solid-state lighting module is reported. The fabrication of the lighting module incorporates assembly and electrical connection of light-emitting diodes (LEDs). The assembly is achieved using a roll-to-roll fluidic self-assembly. The LEDs are sandwiched in-between a stretchable top and bottom electrode to relieve the mechanical stress. The top contact is realized using a lamination technique that eliminates wire-bonding. © 2015 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Platinum thin film resistors as accurate and stable temperature sensors

NASA Technical Reports Server (NTRS)

Diehl, W.

1984-01-01

The measurement characteristics of thin-Pt-film temperature sensors fabricated using advanced methods are discussed. The limitations of wound-wire Pt temperature sensors and the history of Pt-film development are outlined, and the commonly used film-deposition, structuring, and trimming methods are presented in a table. The development of a family of sputtered film resistors is described in detail and illustrated with photographs of the different types. The most commonly used tolerances are reported as + or - 0.3 C + 0.5 percent of the temperature measured.

Miniature Free-Space Electrostatic Ion Thrusters

NASA Technical Reports Server (NTRS)

Hartley, Frank T.; Stephens, James B.

2006-01-01

A miniature electrostatic ion thruster is proposed for maneuvering small spacecraft. In a thruster based on this concept, one or more propellant gases would be introduced into an ionizer based on the same principles as those of the device described in an earlier article, "Miniature Bipolar Electrostatic Ion Thruster". On the front side, positive ions leaving an ionizer element would be accelerated to high momentum by an electric field between the ionizer and an accelerator grid around the periphery of the concave laminate structure. On the front side, electrons leaving an ionizer element would be ejected into free space by a smaller accelerating field. The equality of the ion and electron currents would eliminate the need for an additional electron- or ion-emitting device to keep the spacecraft charge-neutral. In a thruster design consisting of multiple membrane ionizers in a thin laminate structure with a peripheral accelerator grid, the direction of thrust could then be controlled (without need for moving parts in the thruster) by regulating the supply of gas to specific ionizer.

Energy harvesting with stacked dielectric elastomer transducers: Nonlinear theory, optimization, and linearized scaling law

NASA Astrophysics Data System (ADS)

Tutcuoglu, A.; Majidi, C.

2014-12-01

Using principles of damped harmonic oscillation with continuous media, we examine electrostatic energy harvesting with a "soft-matter" array of dielectric elastomer (DE) transducers. The array is composed of infinitely thin and deformable electrodes separated by layers of insulating elastomer. During vibration, it deforms longitudinally, resulting in a change in the capacitance and electrical enthalpy of the charged electrodes. Depending on the phase of electrostatic loading, the DE array can function as either an actuator that amplifies small vibrations or a generator that converts these external excitations into electrical power. Both cases are addressed with a comprehensive theory that accounts for the influence of viscoelasticity, dielectric breakdown, and electromechanical coupling induced by Maxwell stress. In the case of a linearized Kelvin-Voigt model of the dielectric, we obtain a closed-form estimate for the electrical power output and a scaling law for DE generator design. For the complete nonlinear model, we obtain the optimal electrostatic voltage input for maximum electrical power output.

Prediction of Performance of Diamond Wire Saw with Respect to Texture Characteristics of Rock / Prognozowanie Wydajności Pracy Strunowej Piły Diamentowej W Odniesieniu Do Charakterystyki Tekstury Skał

NASA Astrophysics Data System (ADS)

Ghaysari, N.; Ataei, M.; Sereshki, F.; Mikaiel, R.

2012-12-01

In this study, prediction of production rate in diamond wire saw has been investigated. Performance measurements of diamond wire saw carried out in 7 different quarries of carbonate rocks in Iran. For determination textural properties, rock samples were collected from these quarries. At first, a thin section was prepared for each rock and then 5 digital photographs were taken from each section. After this, all images were digitized using AutoCAD software. Then, area, perimeter, longest diameter and shortest diameter were assigned. According to these parameters, all of the other textural characteristics and texture coefficient were determined too. The correlation between sawing rate and textural characteristics were evaluated using multiple and simple regression analyses. Then developed model was validated by P-value test. It was concluded that area, perimeter, diameter equivalent and index of grain size homogeneity are very effective on production rate. Production rate using diamond wire saw can reliably be predicted using developed model.

Shields for Enhanced Protection Against High-Speed Debris

NASA Technical Reports Server (NTRS)

Christiansen, Eric L.; Kerr, Justin H.

2003-01-01

A report describes improvements over the conventional Whipple shield (two thin, spaced aluminum walls) for protecting spacecraft against high-speed impacts of orbiting debris. The debris in question arise mainly from breakup of older spacecraft. The improved shields include exterior bumper layers composed of hybrid fabrics woven from combinations of ceramic fibers and high-density metallic wires or, alternatively, completely metallic outer layers composed of high-strength steel or copper wires. These shields are designed to be light in weight, yet capable of protecting against orbital debris with mass densities up to about 9 g/cm3, without generating damaging secondary debris particles. As yet another design option, improved shields can include sparsely distributed wires made of shape-memory metals that can be thermally activated from compact storage containers to form shields of predetermined shape upon arrival in orbit. The improved shields could also be used to augment shields installed previously.

Shields for Enhanced Protection Against High-Speed Debris

NASA Technical Reports Server (NTRS)

Christiansen, Eric L.; Kerr, Justin H.

2003-01-01

A report describes improvements over the conventional Whipple shield (two thin, spaced aluminum walls) for protecting spacecraft against high-speed impacts of orbiting debris. The debris in question arises mainly from breakup of older spacecraft. The improved shields include exterior "bumper" layers composed of hybrid fabrics woven from combinations of ceramic fibers and high-density metallic wires or, alternatively, completely metallic outer layers composed of high-strength steel or copper wires. These shields are designed to be light in weight, yet capable of protecting against orbital debris with mass densities up to about 9 g/cubic cm, without generating damaging secondary debris particles. As yet another design option, improved shields can include sparsely distributed wires made of shape memory metals that can be thermally activated from compact storage containers to form shields of predetermined shape upon arrival in orbit. The improved shields could also be used to augment shields installed previously.

Spin-polarized current in Zeeman-split d-wave superconductor/quantum wire junctions

NASA Astrophysics Data System (ADS)

Emamipour, Hamidreza

2016-06-01

We study a thin-film quantum wire/unconventional superconductor junction in the presence of an intrinsic exchange field for a d-wave symmetry of the superconducting order parameter. A strongly spin-polarized current is generated due to an interplay between Zeeman splitting of bands and the nodal structure of the superconducting order parameter. We show that strongly spin-polarized current is achievable for both metallic and tunnel junctions. This is because of the presence of a quantum wire (one-dimensional metal) in our junction. While in two-dimensional junctions with both conventional [F. Giazotto, F. Taddei, Phys. Rev. B 77 (2008) 132501] and unconventional [J. Linder, T. Yokoyama, Y. Tanaka, A. Sudbo, Phys. Rev. B 78 (2008) 014516] pairing states, highly spin polarized current takes place just for a tunnel junction. Also, the obtained spin-polarized current is tunable in sign and magnitude in terms of exchange field and applied bias voltage.

Improvement of orthodontic friction by coating archwire with carbon nitride film

NASA Astrophysics Data System (ADS)

Wei, Songbo; Shao, Tianmin; Ding, Peng

2011-10-01

In order to reduce frictional resistance between archwire and bracket during orthodontic tooth movement, carbon nitride (CNx) thin films were deposited on the surface of archwires with ion beam assisted deposition (IBAD). The energy-dispersive X-ray spectrometer (EDS) analysis showed that the CNx film was successfully deposited on the surface of the orthodontic wires. X-ray photoelectron spectroscopy (XPS) analysis suggested that the deposited CNx film was sp 2 carbon dominated structures, and diversiform bonds (N sbnd C, N tbnd C, et al.) coexisted in the film. The friction tests indicated that the CNx film significantly reduced the wire-bracket friction both in ambient air and in artificial saliva. The sp 2C rich structure of the CNx film as well as its protection function for the archwire was responsible for the low friction of the wire-bracket sliding system.

Nanophotonic applications for silicon-on-insulator (SOI)

NASA Astrophysics Data System (ADS)

de la Houssaye, Paul R.; Russell, Stephen D.; Shimabukuro, Randy L.

2004-07-01

Silicon-on-insulator is a proven technology for very large scale integration of microelectronic devices. The technology also offers the potential for development of nanophotonic devices and the ability to interface such devices to the macroscopic world. This paper will report on fabrication techniques used to form nano-structured silicon wires on an insulating structure that is amenable to interfacing nanostructured sensors with high-performance microelectronic circuitry for practical implementation. Nanostructures formed on silicon-on-sapphire can also exploit the transparent substrate for novel device geometries. This research harnesses the unique properties of a high-quality single crystal film of silicon on sapphire and uses the film thickness as one of the confinement dimensions. Lateral arrays of silicon nanowires were fabricated in the thin (5 to 20 nm) silicon layer and studied. This technique offers simplified contact to individual wires and provides wire surfaces that are more readily accessible for controlled alteration and device designs.

IEEE 1988 International Symposium on Electromagnetic Compatibility, Seattle, WA, Aug. 2-4, 1988, Record

NASA Astrophysics Data System (ADS)

Various papers on electromagnetic compatibility are presented. Some of the optics considered include: field-to-wire coupling 1 to 18 GHz, SHF/EHF field-to-wire coupling model, numerical method for the analysis of coupling to thin wire structures, spread-spectrum system with an adaptive array for combating interference, technique to select the optimum modulation indices for suppression of undesired signals for simultaneous range and data operations, development of a MHz RF leak detector technique for aircraft harness surveillance, and performance of standard aperture shielding techniques at microwave frequncies. Also discussed are: spectrum efficiency of spread-spectrum systems, control of power supply ripple produced sidebands in microwave transistor amplifiers, an intership SATCOM versus radar electromagnetic interference prediction model, considerations in the design of a broadband E-field sensing system, unique bonding methods for spacecraft, and review of EMC practice for launch vehicle systems.

Soft J-tipped guide wire-induced cardiac perforation in a patient with right ventricular lipomatosis and wall thinning.

PubMed

Hiroshima, Yuki; Tajima, Katsushi; Shiono, Yousuke; Suzuki, Ikuko; Kohno, Kei; Kato, Yuichi; Shunji, Kawamura; Kato, Takeo

2012-01-01

Cardiac tamponade caused by perforation is a rare but potentially lethal complication of central venous catheter (CVC) insertion. We herein report a case of cardiac perforation associated with the use of a soft J-tipped guide wire. Twenty minutes after the insertion of a CVC, the patient developed unexpected cardiac arrest. An autopsy revealed 400 mL of pericardial blood. The right ventricular wall was 1 mm thick with about 10 myocyte layers, which is one-third that of the normal heart. A histological analysis revealed widespread fatty infiltration of the right ventricular wall (right ventricular lipomatosis).

Micromachined actuators/sensors for intratubular positioning/steering

DOEpatents

Lee, Abraham P.; Krulevitch, Peter A.; Northrup, M. Allen; Trevino, Jimmy C.

1998-01-01

Micromachined thin film cantilever actuators having means for individually controlling the deflection of the cantilevers, valve members, and rudders for steering same through blood vessels, or positioning same within a blood vessel, for example. Such cantilever actuators include tactile sensor arrays mounted on a catheter or guide wire tip for navigation and tissues identification, shape-memory alloy film based catheter/guide wire steering mechanisms, and rudder-based steering devices that allow the selective actuation of rudders that use the flowing blood itself to help direct the catheter direction through the blood vessel. While particularly adapted for medical applications, these cantilever actuators can be used for steering through piping and tubing systems.

Microvalve

DOEpatents

Lee, A.P.; Krulevitch, P.A.; Northrup, M.A.; Trevino, J.C.

1998-10-13

Micromachined thin film cantilever actuators having means for individually controlling the deflection of the cantilevers, valve members, and rudders for steering same through blood vessels, or positioning same within a blood vessel, for example. Such cantilever actuators include tactile sensor arrays mounted on a catheter or guide wire tip for navigation and tissues identification, shape-memory alloy film based catheter/guide wire steering mechanisms, and rudder-based steering devices that allow the selective actuation of rudders that use the flowing blood itself to help direct the catheter direction through the blood vessel. While particularly adapted for medical applications, these cantilever actuators can be used for steering through piping and tubing systems. 14 figs.

Microvalve

DOEpatents

Lee, Abraham P.; Krulevitch, Peter A.; Northrup, M. Allen; Trevino, Jimmy C.

1998-01-01

Micromachined thin film cantilever actuators having means for individually controlling the deflection of the cantilevers, valve members, and rudders for steering same through blood vessels, or positioning same within a blood vessel, for example. Such cantilever actuators include tactile sensor arrays mounted on a catheter or guide wire tip for navigation and tissues identification, shape-memory alloy film based catheter/guide wire steering mechanisms, and rudder-based steering devices that allow the selective actuation of rudders that use the flowing blood itself to help direct the catheter direction through the blood vessel. While particularly adapted for medical applications, these cantilever actuators can be used for steering through piping and tubing systems.

Characterization of stable, electroactive protein cage/synthetic polymer multilayer thin films prepared by layer-by-layer assembly

NASA Astrophysics Data System (ADS)

Uto, Koichiro; Yamamoto, Kazuya; Kishimoto, Naoko; Muraoka, Masahiro; Aoyagi, Takao; Yamashita, Ichiro

2013-04-01

We have fabricated electroactive multilayer thin films containing ferritin protein cages. The multilayer thin films were prepared on a solid substrate by the alternate electrostatic adsorption of (apo)ferritin and poly( N-isopropylacrylamide- co-2-carboxyisopropylacrylamide) (NIPAAm- co-CIPAAm) in pH 3.5 acetate buffer solution. The assembly process was monitored using a quartz crystal microbalance. The (apo)ferritin/poly(NIPAAm- co-CIPAAm) multilayer thin films were then cross-linked using a water-soluble carbodiimide, 1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide. The cross-linked films were stable under a variety of conditions. The surface morphology and thickness of the multilayer thin films were characterized by atomic force microscopy, and the ferritin iron cores were observed by scanning electron microscopy to confirm the assembly mechanism. Cyclic voltammetry measurements showed different electrochemical properties for the cross-linked ferritin and apoferritin multilayer thin films, and the effect of stability of the multilayer film on its electrochemical properties was also examined. Our method for constructing multilayer films containing protein cages is expected to be useful in building more complex functional inorganic nanostructures.

Method for making thin polypropylene film

DOEpatents

Behymer, R.D.; Scholten, J.A.

1985-11-21

An economical method is provided for making uniform thickness polypropylene film as thin as 100 Angstroms. A solution of polypropylene dissolved in xylene is formed by mixing granular polypropylene and xylene together in a flask at an elevated temperature. A substrate, such as a glass plate or microscope slide is immersed in the solution. When the glass plate is withdrawn from the solution at a uniform rate, a thin polypropylene film forms on a flat surface area of the glass plate as the result of xylene evaporation. The actual thickness of the polypropylene film is functional of the polypropylene in xylene solution concentration, and the particular withdrawal rate of the glass plate from the solution. After formation, the thin polypropylene film is floated from the glass plate onto the surface of water, from which it is picked up with a wire hoop.

Development And Testing Of The Inertial Electrostatic Confinement Diffusion Thruster

NASA Technical Reports Server (NTRS)

Becnel, Mark D.; Polzin, Kurt A.

2013-01-01

The Inertial Electrostatic Confinement (IEC) diffusion thruster is an experiment in active development that takes advantage of physical phenomenon that occurs during operation of an IEC device. The IEC device has been proposed as a fusion reactor design that relies on traditional electrostatic ion acceleration and is typically arranged in a spherical geometry. The design incorporates two radially-symmetric spherical electrodes. Often the inner electrode utilizes a grid of wire shaped in a sphere with a radius 15 to 50 percent of the radius of the outer electrode. The inner electrode traditionally has 90 percent or more transparency to allow particles (ions) to pass to the center of the spheres and collide/recombine in the dense plasma core at r=0. When operating the IEC, an unsteady plasma leak is typically observed passing out one of the gaps in the lattice grid of the inner electrode. The IED diffusion thruster is based upon the idea that this plasma leak can be used for propulsive purposes. The IEC diffusion thruster utilizes the radial symmetry found in the IEC device. A cylindrical configuration is employed here as it will produce a dense core of plasma the length of the cylindrical grid while promoting the plasma leak to exhaust through an electromagnetic nozzle at one end of the apparatus. A proof-of-concept IEC diffusion thruster is operational and under testing using argon as propellant (Figure 1).

New Planar Wire Array Experiments on the LTD Generator at U Michigan

NASA Astrophysics Data System (ADS)

Weller, M. E.; Safronova, A. S.; Kantsyrev, V. L.; Shrestha, I.; Shlyaptseva, V. V.; Cooper, M. C.; Lorance, M. Y.; Stafford, A.; Petkov, E. E.; Jordan, N. M.; Patel, S. G.; Steiner, A. M.; Yager-Elorriaga, D. A.; Gilgenbach, R. M.

2014-10-01

Experiments on planar wire array z-pinches have been carried out on the MAIZE Linear Transformer Driver (LTD) generator at the University of Michigan (UM) for the first time. Specifically, Al (Al 5056, 95% Al, 5% Mg) double planar wire arrays (DPWAs) comprising six wires in each plane with interplanar gaps of 3.0 mm and 6.0 mm and interwire gaps of 0.7 mm and 1.0 mm were imploded with x-ray time-integrated spectra indicating electron temperatures of over 450 eV for K-shell Al and Mg, while producing mostly optically thin lines. In addition to x-ray time-integrated spectra, the diagnostics included x-ray time-integrated pinhole cameras, two silicon diodes, and shadowgraphy, which are analyzed and compared. The MAIZE LTD is capable of supplying up 1.0 MA, 100 kV pulses with 100 ns rise time into a matched load. However, for these experiments the LTD was charged to +-70 kV resulting in up to 0.5 MA with a current rise time of approximately 150 ns. Future experiments and the importance of studying planar wire arrays on LTD devices are discussed. This work supported by NNSA under DOE Cooperative Agreement DE-NA0001984. S. Patel & A. Steiner supported by Sandia. D. Yager-Elorriaga supported by NSF GF.

Electrostatic modulation of the electronic properties of Dirac semimetal Na3Bi thin films

NASA Astrophysics Data System (ADS)

Hellerstedt, Jack; Yudhistira, Indra; Edmonds, Mark T.; Liu, Chang; Collins, James; Adam, Shaffique; Fuhrer, Michael S.

2017-10-01

Large-area thin films of topological Dirac semimetal Na3Bi are grown on amorphous SiO2:Si substrates to realize a field-effect transistor with the doped Si acting as a back gate. As-grown films show charge carrier mobilities exceeding 7 000 cm2/V s and carrier densities below 3 ×1018cm-3 , comparable to the best thin-film Na3Bi . An ambipolar field effect and minimum conductivity are observed, characteristic of Dirac electronic systems. The results are quantitatively understood within a model of disorder-induced charge inhomogeneity in topological Dirac semimetals. The hole mobility is significantly larger than the electron mobility in Na3Bi which we ascribe to the inverted band structure. When present, these holes dominate the transport properties.

Wire-grid electromagnetic modelling of metallic cylindrical objects with arbitrary section, for Ground Penetrating Radar applications

NASA Astrophysics Data System (ADS)

Adabi, Saba; Pajewski, Lara

2014-05-01

This work deals with the electromagnetic wire-grid modelling of metallic cylindrical objects, buried in the ground or embedded in a structure, for example in a wall or in a concrete slab. Wire-grid modelling of conducting objects was introduced by Richmond in 1966 [1] and, since then, this method has been extensively used over the years to simulate arbitrarily-shaped objects and compute radiation patterns of antennas, as well as the electromagnetic field scattered by targets. For any wire-grid model, a fundamental question is the choice of the optimum wire radius and grid spacing. The most widely used criterion to fix the wire size is the so-called same-area rule [2], coming from empirical observation: the total surface area of the wires has to be equal to the surface area of the object being modelled. However, just few authors have investigated the validity of this criterion. Ludwig [3] studied the reliability of the rule by examining the canonical radiation problem of a transverse magnetic field by a circular cylinder fed with a uniform surface current, compared with a wire-grid model; he concluded that the same-area rule is optimum and that too thin wires are just as bad as too thick ones. Paknys [4] investigated the accuracy of the same-area rule for the modelling of a circular cylinder with a uniform current on it, continuing the study initiated in [3], or illuminated by a transverse magnetic monochromatic plane wave; he deduced that the same-area rule is optimal and that the field inside the cylinder is most sensitive to the wire radius than the field outside the object, so being a good error indicator. In [5], a circular cylinder was considered, embedded in a dielectric half-space and illuminated by a transverse magnetic monochromatic plane wave; the scattered near field was calculated by using the Cylindrical-Wave Approach and numerical results, obtained for different wire-grid models in the spectral domain, were compared with the exact solution. The Authors demonstrated that the well-known same-area criterion yields affordable results but is quite far from being the optimum: better results can be obtained with a wire radius shorter than what is suggested by the rule. In utility detection, quality controls of reinforced concrete, and other civil-engineering applications, many sought targets are long and thin: in these cases, two-dimensional scattering methods can be employed for the electromagnetic modelling of scenarios. In the present work, the freeware tool GPRMAX2D [6], implementing the Finite-Difference Time-Domain method, is used to implement the wire-grid modelling of buried two-dimensional objects. The source is a line of current, with Ricker waveform. Results obtained in [5] are confirmed in the time domain and for different geometries. The highest accuracy is obtained by shortening the radius of about 10%. It seems that fewer (and larger) wires need minor shortening; however, more detailed investigations are required. We suggest to use at least 8 - 10 wires per wavelength if the field scattered by the structure has to be evaluated. The internal field is much more sensitive to the modelling configuration than the external one, and more wires should be employed when shielding effects are concerned. We plan to conduct a more comprehensive analysis, in order to extract guidelines for wire sizing, to be validated on different shapes. We also look forward to verifying the possibility of using the wire-grid modelling method for the simulation of slotted objects. This work is a contribution to COST Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar". The Authors thanks COST for funding COST Action TU1208. References [1] J.H. Richmond, A wire grid model for scattering by conducting bodies, IEEE Trans. Antennas Propagation AP-14 (1966), pp. 782-786. [2] S.M. Rao, D.R. Wilton, A.W. Glisson, Electromagnetic scattering by surfaces of arbitrary shape, IEEE Trans. Antennas Propagation AP-30 (1982), pp. 409-418. [3] A.C. Ludwig, Wire grid modeling of surfaces, IEEE Trans. Antennas Propagation AP-35 (1987), pp. 1045-1048. [4] R.J. Paknys, The near field of a wire grid model, IEEE Trans. Antennas Propagation 39 (1991), pp. 994-999. [5] F. Frezza, L. Pajewski, C. Ponti, G. Schettini, Accurate wire-grid modelling of buried conducting cylindrical scatterers, Nondestructive Testing and Evaluation (2012), 27, pp. 199-207. [6] A. Giannopoulos, Modelling ground penetrating radar by GPRMAX. Construction and Building Materials (2005), 19, pp. 755-762.

Necessary Conditions for Accurate, Transient Hot-Wire Measurements of the Apparent Thermal Conductivity of Nanofluids are Seldom Satisfied

NASA Astrophysics Data System (ADS)

Antoniadis, Konstantinos D.; Tertsinidou, Georgia J.; Assael, Marc J.; Wakeham, William A.

2016-08-01

The paper considers the conditions that are necessary to secure accurate measurement of the apparent thermal conductivity of two-phase systems comprising nanoscale particles of one material suspended in a fluid phase of a different material. It is shown that instruments operating according to the transient hot-wire technique can, indeed, produce excellent measurements when a finite element method (FEM) is employed to describe the instrument for the exact geometry of the hot wire. Furthermore, it is shown that an approximate analytic solution can be employed with equal success, over the time range of 0.1 s to 1 s, provided that (a) two wires are employed, so that end effects are canceled, (b) each wire is very thin, less than 30 \\upmu m diameter, so that the line source model and the corresponding corrections are valid, (c) low values of the temperature rise, less than 4 K, are employed in order to minimize the effect of convection on the heat transfer in the time of measurement of 1 s, and (d) insulated wires are employed for measurements in electrically conducting or polar liquids to avoid current leakage or other electrical distortions. According to these criteria, a transient hot-wire instrument has been designed, constructed, and employed for the measurement of the enhancement of the thermal conductivity of water when TiO2 or multi-wall carbon nanotubes (MWCNT) are added. These new results, together with a critical evaluation of other measurements, demonstrate the importance of proper implementation of the technique.

Graphene nanoplatelet composite 'paper' as an electrostatic actuator.

PubMed

Yu, Zeyang; Drzal, Lawrence T

2018-08-03

Graphene nanoplatelets (GnP) can be made into a thin 'paper' through vacuum filtration of GnP suspension. Electrodes were fabricated from the compressed GnP paper and then by coating the surface with epoxy. The electrostatic actuator was constructed from two parallel-aligned composite papers fixed at the anode and a cathode connected to ground. The two composite papers would then separate when a voltage was applied. The GnP paper was also modified to increase surface area by introducing porosity or adding ∼10 wt% C750 (GnP with diameter less than 1 μm); or changing the relative permittivity by adding barium titanate particles; or combining these two effects by adding CNCs. Overall the output work could be significantly improved to over 400%.

Crash resistant container

DOEpatents

Pierce, Jim D.

1994-01-01

A container for hazardous materials capable of protecting the enclosed materials from high speed impact. Energy absorption is provided by a multiplicity of crushable layers of either wire mesh or perforated metal sheets which thin and flow together under impact loading. Layers of a higher tensile strength material are interspersed within the crushable layers to confine them and increase performance.

Rugged microelectronic module package supports circuitry on heat sink

NASA Technical Reports Server (NTRS)

Johnson, A. L.

1966-01-01

Rugged module package for thin film hybrid microcircuits incorporated a rigid, thermally conductive support structure, which serves as a heat sink, and a lead wire block in which T-shaped electrical connectors are potted. It protects the circuitry from shock and vibration loads, dissipates internal heat, and simplifies electrical connections between adjacent modules.

Invisible Braces

NASA Technical Reports Server (NTRS)

1989-01-01

Ceradyne, Inc., and 3M Unitek were assisted in the development of Ceramic braces by NIAC/USC. The braces are marketed by Unitek/3M, and are made from translucent polycrystalline alumina (TPA). They are designed for each tooth, connected by a thin metal wire, are strong, aesthetically appealing and as effective clinically as plastic or metal appliances.

Wireless thin film transistor based on micro magnetic induction coupling antenna.

PubMed

Jun, Byoung Ok; Lee, Gwang Jun; Kang, Jong Gu; Kim, Seunguk; Choi, Ji-Woong; Cha, Seung Nam; Sohn, Jung Inn; Jang, Jae Eun

2015-12-22

A wireless thin film transistor (TFT) structure in which a source/drain or a gate is connected directly to a micro antenna to receive or transmit signals or power can be an important building block, acting as an electrical switch, a rectifier or an amplifier, for various electronics as well as microelectronics, since it allows simple connection with other devices, unlike conventional wire connections. An amorphous indium gallium zinc oxide (α-IGZO) TFT with magnetic antenna structure was fabricated and studied for this purpose. To enhance the induction coupling efficiency while maintaining the same small antenna size, a magnetic core structure consisting of Ni and nanowires was formed under the antenna. With the micro-antenna connected to a source/drain or a gate of the TFT, working electrical signals were well controlled. The results demonstrated the device as an alternative solution to existing wire connections which cause a number of problems in various fields such as flexible/wearable devices, body implanted devices, micro/nano robots, and sensors for the 'internet of things' (IoT).

Wireless thin film transistor based on micro magnetic induction coupling antenna

PubMed Central

Jun, Byoung Ok; Lee, Gwang Jun; Kang, Jong Gu; Kim, Seunguk; Choi, Ji-Woong; Cha, Seung Nam; Sohn, Jung Inn; Jang, Jae Eun

2015-01-01

A wireless thin film transistor (TFT) structure in which a source/drain or a gate is connected directly to a micro antenna to receive or transmit signals or power can be an important building block, acting as an electrical switch, a rectifier or an amplifier, for various electronics as well as microelectronics, since it allows simple connection with other devices, unlike conventional wire connections. An amorphous indium gallium zinc oxide (α-IGZO) TFT with magnetic antenna structure was fabricated and studied for this purpose. To enhance the induction coupling efficiency while maintaining the same small antenna size, a magnetic core structure consisting of Ni and nanowires was formed under the antenna. With the micro-antenna connected to a source/drain or a gate of the TFT, working electrical signals were well controlled. The results demonstrated the device as an alternative solution to existing wire connections which cause a number of problems in various fields such as flexible/wearable devices, body implanted devices, micro/nano robots, and sensors for the ‘internet of things’ (IoT). PMID:26691929

Effects of end-ring/shield configuration on homogeneity and signal-to-noise ratio in a birdcage-type coil loaded with a human head.

PubMed

Liu, Wanzhan; Collins, Christopher M; Delp, Pamela J; Smith, Michael B

2004-01-01

We modeled four different end-ring/shield configurations of a birdcage coil to examine their effects on field homogeneity and signal-to-noise ratio (SNR) at 64 MHz and 125 MHz. The configurations are defined as: 1) conventional: a conventional cylindrical shield; 2) surrounding shield: a shield with annular extensions to closely shield the end rings; 3) solid connection: a shield with annular extensions connected to the rungs; and 4) thin wire connection: a shield with thin wires connected to the rungs. At both frequencies, the coil with conventional end-ring/shield configuration produces the most homogeneous RF magnetic (B1) field when the coil is empty, but produces the least homogeneous B1 field when the coil is loaded with a human head. The surrounding shield configuration results in the most homogeneous B1 and highest SNR in the coil loaded with the human head at both frequencies, followed closely by the solid connection configuration. Copyright 2003 Wiley-Liss, Inc.

Wireless thin film transistor based on micro magnetic induction coupling antenna

NASA Astrophysics Data System (ADS)

Jun, Byoung Ok; Lee, Gwang Jun; Kang, Jong Gu; Kim, Seunguk; Choi, Ji-Woong; Cha, Seung Nam; Sohn, Jung Inn; Jang, Jae Eun

2015-12-01

A wireless thin film transistor (TFT) structure in which a source/drain or a gate is connected directly to a micro antenna to receive or transmit signals or power can be an important building block, acting as an electrical switch, a rectifier or an amplifier, for various electronics as well as microelectronics, since it allows simple connection with other devices, unlike conventional wire connections. An amorphous indium gallium zinc oxide (α-IGZO) TFT with magnetic antenna structure was fabricated and studied for this purpose. To enhance the induction coupling efficiency while maintaining the same small antenna size, a magnetic core structure consisting of Ni and nanowires was formed under the antenna. With the micro-antenna connected to a source/drain or a gate of the TFT, working electrical signals were well controlled. The results demonstrated the device as an alternative solution to existing wire connections which cause a number of problems in various fields such as flexible/wearable devices, body implanted devices, micro/nano robots, and sensors for the ‘internet of things’ (IoT).

Chromophore Poling in Thin Films of Organic Glasses. 2. Two-Electrode Corona Discharge Setup

NASA Astrophysics Data System (ADS)

Vilitis, O.; Muzikante, I.; Rutkis, M.; Vembris, A.

2012-01-01

In Part 1 of the article we provided description of the corona discharge physics and overview of the methods used for corona poling in thin organic films. Subsequent sections describe comparatively simple technical methods for poling the organic nonlinear optical polymers using a two-electrode (point-to-plate or wire-to-plate) technique. The polarization build-up was studied by the DC positive corona method for poling the nonlinear optical (NLO) polymers. The experimental setup provides the corona discharge current from 0.5 μA up to 3 μA by applying 3 kV - 12 kV voltage to the corona electrode and makes possible selection among the types of corona electrodes (needle, multi-needle, wire, etc.). The results of experimental testing of the poling setup show that at fixed optimal operational parameters of poling - the sample orientation temperature and the discharge current - the corona charging of polymeric materials can successfully be performed applying the two-electrode technique. To study the dynamics of both poling and charge transport processes the three-electrode charging system - a corona triode - should be applied.

Accurate measurements of the thermal diffusivity of thin filaments by lock-in thermography

NASA Astrophysics Data System (ADS)

Salazar, Agustín; Mendioroz, Arantza; Fuente, Raquel; Celorrio, Ricardo

2010-02-01

In lock-in (modulated) thermography the lateral thermal diffusivity can be obtained from the slope of the linear relation between the phase of the surface temperature and the distance to the heating spot. However, this slope is greatly affected by heat losses, leading to an overestimation of the thermal diffusivity, especially for thin samples of poor thermal conducting materials. In this paper, we present a complete theoretical model to calculate the surface temperature of filaments heated by a focused and modulated laser beam. All heat losses have been included: conduction to the gas, convection, and radiation. Monofilaments and coated wires have been studied. Conduction to the gas has been identified as the most disturbing effect preventing from the direct use of the slope method to measure the thermal diffusivity. As a result, by keeping the sample in vacuum a slope method combining amplitude and phase can be used to obtain the accurate diffusivity value. Measurements performed in a wide variety of filaments confirm the validity of the conclusion. On the other hand, in the case of coated wires, the slope method gives an effective thermal diffusivity, which verifies the in-parallel thermal resistor model. As an application, the slope method has been used to retrieve the thermal conductivity of thin tubes by filling them with a liquid of known thermal properties.

Influence of orientation mismatch on charge transport across grain boundaries in tri-isopropylsilylethynyl (TIPS) pentacene thin films.

PubMed

Steiner, Florian; Poelking, Carl; Niedzialek, Dorota; Andrienko, Denis; Nelson, Jenny

2017-05-03

We present a multi-scale model for charge transport across grain boundaries in molecular electronic materials that incorporates packing disorder, electrostatic and polarisation effects. We choose quasi two-dimensional films of tri-isopropylsilylethynyl pentacene (TIPS-P) as a model system representative of technologically relevant crystalline organic semiconductors. We use atomistic molecular dynamics, with a force-field specific for TIPS-P, to generate and equilibrate polycrystalline two-dimensional thin films. The energy landscape is obtained by calculating contributions from electrostatic interactions and polarization. The variation in these contributions leads to energetic barriers between grains. Subsequently, charge transport is simulated using a kinetic Monte-Carlo algorithm. Two-grain systems with varied mutual orientation are studied. We find relatively little effect of long grain boundaries due to the presence of low impedance pathways. However, effects could be more pronounced for systems with limited inter-grain contact areas. Furthermore, we present a lattice model to generalize the model for small molecular systems. In the general case, depending on molecular architecture and packing, grain boundaries can result in interfacial energy barriers, traps or a combination of both with qualitatively different effects on charge transport.

Computational study of graphene-based vertical field effect transistor

NASA Astrophysics Data System (ADS)

Chen, Wenchao; Rinzler, Andrew; Guo, Jing

2013-03-01

Poisson and drift-diffusion equations are solved in a three-dimensional device structure to simulate graphene-based vertical field effect transistors (GVFETs). Operation mechanisms of the GVFET with and without punched holes in the graphene source contact are presented and compared. The graphene-channel Schottky barrier can be modulated by gate electric field due to graphene's low density of states. For the graphene contact with punched holes, the contact barrier thinning and lowering around punched hole edge allow orders of magnitude higher tunneling current compared to the region away from the punched hole edge, which is responsible for significant performance improvement as already verified by experiments. Small hole size is preferred due to less electrostatic screening from channel inversion layer, which gives large electric field around the punched hole edge, thus, leading to a thinner and lower barrier. Bilayer and trilayer graphenes as the source contact degrade the performance improvement because stronger electrostatic screening leads to smaller contact barrier lowering and thinning. High punched hole area percentage improves current performance by allowing more gate electric field to modulate the graphene-channel barrier. Low effective mass channel material gives better on-off current ratio.

Self-Healing Technologies for Wiring and Surfaces in Aerospace and Deep Space Exploration Applications

NASA Technical Reports Server (NTRS)

Williams, Martha Kay; Gibson, Tracy L.; Jolley, Scott T.; Caraccio-Meier, Anne Joan

2017-01-01

Self-healing technologies have been identified as critical technology gaps for future exploration. NASA and KSC have been working in this area for multiple years with established intellectual property; however, there are many challenges that remain in this area of research. How do we mimic what the body does so naturally when we as NASA have unique requirements? We have been investigating several mechanisms for self-healing: microencapsulation with a healant core to fill in voids in the case of mechanical puncture and flowable (or sealable)systems that have inherent chemical properties that allow the materials to flow back together when cut or damaged. The microcapsules containing healant have to be durable and robust, must be able to take high temperatures to meet NASA unique requirements, provide good capillary flow of the healant, and be small in diameters to fill in damage voids in thin films or surfaces. Sealable systems have to flow in a range of temperatures and yet be lightweight and chemically resistant. The systems currently being developed are based on polyimide and polyurethane matrices and have been studied for use in high performance wiring systems, inflatable systems, and habitation structures. Self-healing or self-sealing capability would significantly reduce maintenance requirements and increase the safety and reliability performance of critical systems. Advances in these self-healing technologies and some of the unique challenges needed to be overcome in order to incorporate a self-healing mechanism into wiring or thin films systems will be addressed.

Optimizing the sensing performance of a single-rod fluxgate magnetometer using thin magnetic wires

NASA Astrophysics Data System (ADS)

Can, Hava; Svec, Peter, Jr.; Tanrıseven, Sercan; Bydzovsky, Jan; Birlikseven, Cengiz; Sözeri, Hüseyin; Svec, Peter, Sr.; Topal, Uğur

2015-11-01

This paper presents the optimal conditions for the design of a single-rod fluxgate magnetometer using Co-based amorphous magnetic wires with reduced geometrical dimensions of 100 μm in diameter. In order to enhance the performance of the current sensor (i.e. the noise level, the sensitivity, the dynamical range, the scaling factor, etc), the core materials were subjected to annealing at different annealing temperatures in a longitudinal magnetic field ranging from 0 to 0.5 T. The B-H measurements have shown that the heat treatments significantly change the magnetic parameters of the cores (the saturation field, the initial and apparent permeabilities). For instance, the initial permeability μ i attains values of between 3500 and 4700 depending on the treatment conditions. These magnetic parameters were subsequently correlated with the sensor performance by using the principles of the fluxgate physics. Consequently, the enhanced fluxgate effect with improved sensing characteristics has been obtained by annealing the wire core at 250 °C (B  =  0 T). It is shown that this magnetic wire with a sensing area of 0.00785 mm2 is suitable as a sensor core for the nondestructive testing of metallic objects and the surfaces of magnetic cards. The sensor signal shows perfect linear dependence to dc or low frequency fields up to ~1 Oe. The fitting parameters R 2 of 0.9998 could be achieved in a dc field interval of  -1.0 Oe and 1.0 Oe (when R 2  =1.0, all points lie exactly on the curve with no scatter). Such linearity has not been seen in such a large dynamical range until now in the rod-type single-core fluxgates. It is also shown that there is no hysteresis on the V 2f -H dc graphs (the V 2f is the sensor signal) even after applying fields as high as 100 Oe. Besides, the cross-field effect is almost zero due to the geometry of the long-thin wire.

Earth's field NMR; a surface moisture detector?

NASA Astrophysics Data System (ADS)

Fukushima, Eiichi; Altobelli, Stephen; McDowell, Andrew; Zhang, Tongsheng

2012-10-01

Earth's field NMR (EFNMR), being free of magnets, would be an ideal teaching medium as well as a mobile NMR technique except for its weak S/N. The common EFNMR apparatus uses a powerful prepolarization field to enhance the spin magnetization before the experiment. We introduce a coil design geared to larger but manageable samples with sufficient sensitivity without prepolarization to move EFNMR closer to routine use and to provide an inexpensive teaching tool. Our coil consists of parallel wires spread out on a plywood to form a current sheet with the current return wires separated so they will not influence the main part of the coil assembly. The sensitive region is a relatively thin region parallel to the coil and close to it. A single turn of the coil is wound to be topologically equivalent to a figure-8. The two crossing segments in the center of a figure-8 form two of the parallel wires of the flat coil. Thus, a two-turn figure-8 has four crossing wires so its topologically equivalent coil will have four parallel wires with currents in phase. Together with the excellent sensitivity, this coil offers outstanding interference rejection because of the figure-8 geometry. An example of such a coil has 328 parallel wires covering a ˜1 meter square plywood which yields a good NMR signal from 26 liters of water spread out roughly over the area of the coil in less than one minute in a nearby park.

Embedding of Superelastic SMA Wires into Composite Structures: Evaluation of Impact Properties

NASA Astrophysics Data System (ADS)

Pappadà, Silvio; Rametta, Rocco; Toia, Luca; Coda, Alberto; Fumagalli, Luca; Maffezzoli, Alfonso

2009-08-01

Shape memory alloy (SMA) represents the most versatile way to realize smart materials with sensing, controlling, and actuating functions. Due to their unique mechanical and thermodynamic properties and to the possibility to obtain SMA wires with very small diameters, they are used as smart components embedded into the conventional resins or composites, obtaining active abilities, tunable properties, self-healing properties, and damping capacity. Moreover, superelastic SMAs are used to increase the impact resistance properties of composite materials. In this study, the influence of the integration of thin superelastic wires to suppress propagating damage of composite structures has been investigated. Superelastic SMAs have very high strain to failure and recoverable elastic strain, due to a stress-induced martensitic phase transition creating a plateau region in the stress-strain curve. NiTi superelastic wires ( A f = -15 °C fully annealed) of 0.10 mm in diameter have been produced and characterized by SAES Getters. The straight annealed wire shows the typical flag stress-strain behavior. The measured loading plateau is about 450 MPa at ambient temperature with a recoverable elastic strain of more than 6%. For these reasons superelastic SMA fibers can absorb much more strain energy than other fibers before their failure, partly with a constant stress level. In this paper, the improvement of composite laminates impact properties by embedding SMA wires is evaluated and indications for design and manufacturing of SMA composites with high-impact properties are also given.

A multiscale model for charge inversion in electric double layers

NASA Astrophysics Data System (ADS)

Mashayak, S. Y.; Aluru, N. R.

2018-06-01

Charge inversion is a widely observed phenomenon. It is a result of the rich statistical mechanics of the molecular interactions between ions, solvent, and charged surfaces near electric double layers (EDLs). Electrostatic correlations between ions and hydration interactions between ions and water molecules play a dominant role in determining the distribution of ions in EDLs. Due to highly polar nature of water, near a surface, an inhomogeneous and anisotropic arrangement of water molecules gives rise to pronounced variations in the electrostatic and hydration energies of ions. Classical continuum theories fail to accurately describe electrostatic correlations and molecular effects of water in EDLs. In this work, we present an empirical potential based quasi-continuum theory (EQT) to accurately predict the molecular-level properties of aqueous electrolytes. In EQT, we employ rigorous statistical mechanics tools to incorporate interatomic interactions, long-range electrostatics, correlations, and orientation polarization effects at a continuum-level. Explicit consideration of atomic interactions of water molecules is both theoretically and numerically challenging. We develop a systematic coarse-graining approach to coarse-grain interactions of water molecules and electrolyte ions from a high-resolution atomistic scale to the continuum scale. To demonstrate the ability of EQT to incorporate the water orientation polarization, ion hydration, and electrostatic correlations effects, we simulate confined KCl aqueous electrolyte and show that EQT can accurately predict the distribution of ions in a thin EDL and also predict the complex phenomenon of charge inversion.

Optimization and experimental validation of electrostatic adhesive geometry

NASA Astrophysics Data System (ADS)

Ruffatto, D.; Shah, J.; Spenko, M.

This paper introduces a method to optimize the electrode geometry of electrostatic adhesives for robotic gripping, attachment, and manipulation applications. Electrostatic adhesion is achieved by applying a high voltage potential, on the order of kV, to a set of electrodes, which generates an electric field. The electric field polarizes the substrate material and creates an adhesion force. Previous attempts at creating electro-static adhesives have shown them to be effective, but researchers have made no effort to optimize the electrode configuration and geometry. We have shown that by optimizing the geometry of the electrode configuration, the electric field strength, and therefore the adhesion force, is enhanced. To accomplish this, Comsol Multiphysics was utilized to evaluate the average electric field generated by a given electrode geometry. Several electrode patterns were evaluated, including parallel conductors, concentric circles, Hilbert curves (a fractal geometry) and spirals. The arrangement of the electrodes in concentric circles with varying electrode widths proved to be the most effective. The most effective sizing was to use the smallest gap spacing allowable coupled with a variable electrode width. These results were experimentally validated on several different surfaces including drywall, wood, tile, glass, and steel. A new manufacturing process allowing for the fabrication of thin, conformal electro-static adhesive pads was utilized. By combining the optimized electrode geometry with the new fabrication process we are able to demonstrate a marked improvement of up to 500% in shear pressure when compared to previously published values.

Plastohydrodynamic drawing and coating of stainless steel wire using a tapered bore die of no metal to metal contact

NASA Astrophysics Data System (ADS)

Hasan, S.; Basmage, O.; Stokes, J. T.; Hashmi, M. S. J.

2018-05-01

A review of wire coating studies using plasto-hydrodynamic pressure shows that most of the works were carried out by conducting experiments simultaneously with simulation analysis based upon Bernoulli's principle and Euler and Navier-Stokes (N-S) equations. These characteristics relate to the domain of Computational Fluid Dynamics (CFD) which is an interdisciplinary topic (Fluid Mechanics, Numerical Analysis of Fluid flow and Computer Science). This research investigates two aspects: (i) simulation work and (ii) experimentation. A mathematical model was developed to investigate the flow pattern of the molten polymer and pressure distribution within the wire-drawing dies, assessment of polymer coating thickness on the coated wires and speed of coating on the wires at the outlet of the drawing dies, without deploying any pressurizing pump. In addition to a physical model which was developed within ANSYS™ environment through the simulation design of ANSYS™ Workbench. The design was customized to simulate the process of wire-coating on the fine stainless-steel wires using drawing dies having different bore geometries such as: stepped parallel bore, tapered bore and combined parallel and tapered bore. The convergence of the designed CFD model and numerical and physical solution parameters for simulation were dynamically monitored for the viscous flow of the polypropylene (PP) polymer. Simulation results were validated against experimental results and used to predict the ideal bore shape to produce a thin coating on stainless wires with different diameter. Simulation studies confirmed that a specific speed should be attained by the stainless-steel wires while passing through the drawing dies. It has been observed that all the speed values within specific speed range did not produce a coating thickness having the desired coating characteristic features. Therefore, some optimization of the experimental set up through design of experiments (Stat-Ease) was applied to validate the results. Further rapid solidification of the viscous coating on the wires was targeted so that the coated wires do not stick to the winding spool after the coating process.

Application of Thin-Film Thermocouples to Localized Heat Transfer Measurements

NASA Technical Reports Server (NTRS)

Lepicovsky, J.; Bruckner, R. J.; Smith, F. A.

1995-01-01

The paper describes a proof-of-concept experiment on thin-film thermocouples used for localized heat transfer measurements applicable to experiments on hot parts of turbine engines. The paper has three main parts. The first part describes the thin-film sensors and manufacturing procedures. Attention is paid to connections between thin-film thermocouples and lead wires, which has been a source of problems in the past. The second part addresses the test arrangement and facility used for the heat transfer measurements modeling the conditions for upcoming warm turbine tests at NASA LeRC. The paper stresses the advantages of a modular approach to the test rig design. Finally, we present the results of bulk and local heat flow rate measurements, as well as overall heat transfer coefficients obtained from measurements in a narrow passage with an aspect ratio of 11.8. The comparison of bulk and local heat flow rates confirms applicability of thin-film thermocouples to upcoming warm turbine tests.

Theoretical studies of growth processes and electronic properties of nanostructures on surfaces

NASA Astrophysics Data System (ADS)

Mo, Yina

Low dimensional nanostructures have been of particular interest because of their potential applications in both theoretical studies and industrial use. Although great efforts have been put into obtaining better understanding of the formation and properties of these materials, many questions still remain unanswered. This thesis work has focused on theoretical studies of (1) the growth processes of magnetic nanowires on transition-metal surfaces, (2) the dynamics of pentacene thin-film growth and island structures on inert surfaces, and (3) our proposal of a new type of semiconducting nanotube. In the first study, we elucidated a novel and intriguing kinetic pathway for the formation of Fe nanowires on the upper edge of a monatomic-layer-high step on Cu(111) using first-principles calculations. The identification of a hidden fundamental Fe basal line within the Cu steps prior to the formation of the apparent upper step edge Fe wire produces a totally different view of step-decorating wire structures and offers new possibilities for the study of the properties of these wires. Subsequent experiments with scanning tunneling microscopy unambiguously established the essential role of embedded Fe atoms as precursors to monatomic wire growth. A more general study of adatom behavior near transition-metal step edges illustrated a systematic trend in the adatom energetics and kinetics, resulted from the electronic interactions between the adatom and the surfaces. This work opens the possibility of controlled manufacturing of one-dimensional nanowires. In the second study, we investigated pentacene thin-films on H-diamond, H-silica and OH-silica surfaces via force field molecular dynamics simulations. Pentacene island structures on these surfaces were identified and found to have a 90-degree rotation relative to the structure proposed by some experimental groups. Our work may facilitate the design and control of experimental pentacene thin-film growth, and thus the development of organic thin-film transistors. Finally, in our third study, we proposed a new type of structurally simple and energetically stable cyanide transition metal nanotube, based on the planar structure of M(CN)2, (M = Ni, Pd, Pt). These nanotubes have semiconducting character with large band gaps (2--3 eV), which are insensitive to the chirality and diameter. We have investigated the energetic, electronic, and mechanical properties of these materials in both planar and tubular forms through first-principles density functional calculations. These calculations reveal interesting multi-center bonding features that should lead to preferential growth of tubes of a particular chirality. The unique features of these nanotubes should make them capable of being mass-produced, which is one of the most significant shortcomings of semiconducting carbon nanotubes.

Comparison of analytic and iterative digital tomosynthesis reconstructions for thin slab objects

NASA Astrophysics Data System (ADS)

Yun, J.; Kim, D. W.; Ha, S.; Kim, H. K.

2017-11-01

For digital x-ray tomosynthesis of thin slab objects, we compare the tomographic imaging performances obtained from the filtered backprojection (FBP) and simultaneous algebraic reconstruction (SART) algorithms. The imaging performance includes the in-plane molulation-transfer function (MTF), the signal difference-to-noise ratio (SDNR), and the out-of-plane blur artifact or artifact-spread function (ASF). The MTF is measured using a thin tungsten-wire phantom, and the SDNR and the ASF are measured using a thin aluminum-disc phantom embedded in a plastic cylinder. The FBP shows a better MTF performance than the SART. On the contrary, the SART outperforms the FBP with regard to the SDNR and ASF performances. Detailed experimental results and their analysis results are described in this paper. For a more proper use of digital tomosynthesis technique, this study suggests to use a reconstuction algorithm suitable for application-specific purposes.

Micromachined actuators/sensors for intratubular positioning/steering

DOEpatents

Lee, A.P.; Krulevitch, P.A.; Northrup, M.A.; Trevino, J.C.

1998-06-30

Micromachined thin film cantilever actuators having means for individually controlling the deflection of the cantilevers, valve members, and rudders for steering same through blood vessels, or positioning same within a blood vessel, for example. Such cantilever actuators include tactile sensor arrays mounted on a catheter or guide wire tip for navigation and tissues identification, shape-memory alloy film based catheter/guide wire steering mechanisms, and rudder-based steering devices that allow the selective actuation of rudders that use the flowing blood itself to help direct the catheter direction through the blood vessel. While particularly adapted for medical applications, these cantilever actuators can be used for steering through piping and tubing systems. 14 figs.

Ablative Laser Propulsion Using Multi-Layered Material Systems

NASA Technical Reports Server (NTRS)

Nehls, Mary; Edwards, David; Gray, Perry; Schneider, T.

2002-01-01

Experimental investigations are ongoing to study the force imparted to materials when subjected to laser ablation. When a laser pulse of sufficient energy density impacts a material, a small amount of the material is ablated. A torsion balance is used to measure the momentum produced by the ablation process. The balance consists of a thin metal wire with a rotating pendulum suspended in the middle. The wire is fixed at both ends. Recently, multi-layered material systems were investigated. These multi-layered materials were composed of a transparent front surface and opaque sub surface. The laser pulse penetrates the transparent outer surface with minimum photon loss and vaporizes the underlying opaque layer.

An electrode to record the mouse cornea electroretinogram.

PubMed

Goto, Y

The mouse has become a popular model for the study of retinal degeneration, but an electrode suitable for recording electroretinograms from the mouse cornea is not available commercially. I developed a simple electrode suitable for the relatively small mouse eye by attaching a thin stainless-steel wire through the barrel of a 1-cc syringe. The end of the wire is formed into a coil by wrapping it around a 0.5- or 1.0-mm pin. The syringe barrel serves as a convenient way to hold the electrode in a goose-neck holder. This electrode has been used successfully to obtain electroretinograms from hundreds of mice as young as 14 days.

Surface tension of flowing soap films

NASA Astrophysics Data System (ADS)

Sane, Aakash; Mandre, Shreyas; Kim, Ildoo

2018-04-01

The surface tension of flowing soap films is measured with respect to the film thickness and the concentration of soap solution. We perform this measurement by measuring the curvature of the nylon wires that bound the soap film channel and use the measured curvature to parametrize the relation between the surface tension and the tension of the wire. We find the surface tension of our soap films increases when the film is relatively thin or made of soap solution of low concentration, otherwise it approaches an asymptotic value 30 mN/m. A simple adsorption model with only two parameters describes our observations reasonably well. With our measurements, we are also able to measure Gibbs elasticity for our soap film.

Electron-phonon interactions in semiconductor nanostructures

NASA Astrophysics Data System (ADS)

Yu, Segi

In this dissertation, electron-phonon interactions are studied theoretically in semiconductor nanoscale heterostructures. Interactions of electrons with interface optical phonons dominate over other electron-phonon interactions in narrow width heterostructures. Hence, a transfer matrix method is used to establish a formalism for determining the dispersion relations and electrostatic potentials of the interface phonons for multiple-interface heterostructure within the macroscopic dielectric continuum model. This method facilitates systematic calculations for complex structures where the conventional method is difficult to implement. Several specific cases are treated to illustrate advantages of the formalism. Electrophonon resonance (EPR) is studied in cylindrical quantum wires using the confined/interface optical phonons representation and bulk phonon representation. It has been found that interface phonon contribution to EPR is small compared with confined phonon. Different selection rules for bulk phonons and confined phonons result in different EPR behaviors as the radius of cylindrical wire changes. Experiment is suggested to test which phonon representation is appropriate for EPR. The effects of phonon confinement on elect ron-acoustic-phonon scattering is studied in cylindrical and rectangular quantum wires. In the macroscopic elastic continuum model, the confined-phonon dispersion relations are obtained for several crystallographic directions with free-surface and clamped-surface boundary conditions in cylindrical wires. The scattering rates due to the deformation potential are obtained for these confined phonons and are compared with those of bulk-like phonons. The results show that the inclusion of acoustic phonon confinement may be crucial for calculating accurate low-energy electron scattering rates. Furthermore, it has been found that there is a scaling rule governing the directional dependence of the scattering rates. The Hamiltonian describing the deformation-potential of confined acoustic phonons is derived by quantizing the appropriate, experimentally verified approximate compressional acoustic-phonon modes in a free-standing rectangular quantum wire. The scattering rate is obtained for GaAs quantum wires with a range of cross-sectional dimensions. The results demonstrate that a proper treatment of confined acoustic phonons may be essential to correctly model electron scattering rates at low energies in nanoscale structures.

Self-organised fractional quantisation in a hole quantum wire

NASA Astrophysics Data System (ADS)

Gul, Y.; Holmes, S. N.; Myronov, M.; Kumar, S.; Pepper, M.

2018-03-01

We have investigated hole transport in quantum wires formed by electrostatic confinement in strained germanium two-dimensional layers. The ballistic conductance characteristics show the regular staircase of quantum levels with plateaux at n2e 2/h, where n is an integer, e is the fundamental unit of charge and h is Planck’s constant. However as the carrier concentration is reduced, the quantised levels show a behaviour that is indicative of the formation of a zig-zag structure and new quantised plateaux appear at low temperatures. In units of 2e 2/h the new quantised levels correspond to values of n  =  1/4 reducing to 1/8 in the presence of a strong parallel magnetic field which lifts the spin degeneracy but does not quantise the wavefunction. A further plateau is observed corresponding to n  =  1/32 which does not change in the presence of a parallel magnetic field. These values indicate that the system is behaving as if charge was fractionalised with values e/2 and e/4, possible mechanisms are discussed.

Hydrogen Bond Networks and Hydrophobic Effects in the Amyloid β30-35 Chain in Water: A Molecular Dynamics Study.

PubMed

Jong, KwangHyok; Grisanti, Luca; Hassanali, Ali

2017-07-24

We have studied the conformational landscape of the C-terminal fragment of the amyloid protein Aβ 30-35 in water using well-tempered metadynamics simulations and found that it resembles an intrinsically disordered protein. The conformational fluctuations of the protein are facilitated by a collective reorganization of both protein and water hydrogen bond networks, combined with electrostatic interactions between termini as well as hydrophobic interactions of the side chains. The stabilization of hydrophobic interactions in one of the conformers involves a collective collapse of the side chains along with a squeeze-out of water sandwiched between them. The charged N- and C-termini play a critical role in stabilizing different types of protein conformations, including those involving contact-ion salt bridges as well as solvent-mediated interactions of the termini and the amide backbone. We have examined this by probing the distribution of directed water wires forming the hydrogen bond network enveloping the polypeptide. Water wires and their fluctuations form an integral part of structural signature of the protein conformation.

A 18 m 2 cylindrical tracking detector made of 2.6 m long, stereo mylar straw tubes with 100 μm resolution

NASA Astrophysics Data System (ADS)

Benussi, L.; Bertani, M.; Bianco, S.; Fabbri, F. L.; Gianotti, P.; Giardoni, M.; Ghezzo, A.; Guaraldo, C.; Lanaro, A.; Locchi, P.; Lu, J.; Lucherini, V.; Mecozzi, A.; Pace, E.; Passamonti, L.; Qaisar, N.; Ricciardi, A.; Sarwar, S.; Serdyouk, V.; Trasatti, L.; Volkov, A.; Zia, A.

1998-12-01

An array of 2424 2.6 m-long, 15 mm-diameter mylar straw tubes, arranged in two axial and four stereo layers, has been assembled. The array covers a cylindrical tracking surface of 18 m 2 and provides coordinate measurement in the drift direction and along the wire. A correction of the systematic effects which are introduced by gravitational sag and electrostatics, thus dominating the detector performance especially with long straws, allows to determine wire position from drift-time distribution. The correction has been applied to reach a space resolution of 40 μm with DME, 100 μm with Ar+C 2H 6, and 100-200 μm with CO 2. Such a resolution is the best ever obtained for straws of these dimensions. A study of the gas leakage for the straw system has been performed, and results are reported. The array is being commissioned as a subdetector of the FINUDA spectrometer, and tracking performances are being studied with cosmic rays.

Growing InGaAs quasi-quantum wires inside semi-rhombic shaped planar InP nanowires on exact (001) silicon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han, Yu; Li, Qiang; Lau, Kei May, E-mail: eekmlau@ust.hk

We report InGaAs quasi-quantum wires embedded in planar InP nanowires grown on (001) silicon emitting in the 1550 nm communication band. An array of highly ordered InP nanowire with semi-rhombic cross-section was obtained in pre-defined silicon V-grooves through selective-area hetero-epitaxy. The 8% lattice mismatch between InP and Si was accommodated by an ultra-thin stacking disordered InP/GaAs nucleation layer. X-ray diffraction and transmission electron microscope characterizations suggest excellent crystalline quality of the nanowires. By exploiting the morphological evolution of the InP and a self-limiting growth process in the V-grooves, we grew embedded InGaAs quantum-wells and quasi-quantum-wires with tunable shape and position. Roommore » temperature analysis reveals substantially improved photoluminescence in the quasi-quantum wires as compared to the quantum-well reference, due to the reduced intrusion defects and enhanced quantum confinement. These results show great promise for integration of III-V based long wavelength nanowire lasers on the well-established (001) Si platform.« less

Miniaturized optoelectronic system for telemetry of in vivo voltammetric signals.

PubMed

De Simoni, M G; De Luigi, A; Imeri, L; Algeri, S

1990-08-01

In vivo voltammetry is an electrochemical technique that uses carbon fiber microelectrodes stereotaxically implanted in brain areas to monitor monoamine metabolism and release continuously, in freely moving animals. Electric wires connect the polarograph to the animal. A wire-less transmission system (optoelectronic transmission, OPT) of voltammetric signals is described here. It uses infrared diffused light, exploiting the diffusion of the transmitted light over walls and ceiling towards a receiver. The transmission system consists of a main unit and a satellite unit (40 x 30 x 5 mm) positioned on the animal's back. Voltammetric recordings obtained by the classical system (with wires) and by OPT are well defined and almost identical in shape. The power supply is provided by two thin lithium batteries (+/- 3V) that can record for up to 20 h. OPT permits detailed behavioral observations since the animal can be left free to move in a spacious environment. Voltammetry using OPT allows simultaneous recording of neuronal firing activity as well as electroencephalographic recordings (EEG) since there is no cross-talk between the circuits used. The results illustrate the reliability and usefulness of this wire-less transmission system for studying relationships between neurochemical, behavioral and electrophysiological activities.

Crash resistant container

DOEpatents

Pierce, J.D.

1994-08-16

A container for hazardous materials capable of protecting the enclosed materials from high speed impact is disclosed. Energy absorption is provided by a multiplicity of crushable layers of either wire mesh or perforated metal sheets which thin and flow together under impact loading. Layers of a higher tensile strength material are interspersed within the crushable layers to confine them and increase performance. 1 fig.

Method and apparatus for conducting variable thickness vapor deposition

DOEpatents

Nesslage, G.V.

1984-08-03

A method of vapor depositing metal on a substrate in variable thickness comprises conducting the deposition continuously without interruption to avoid formation of grain boundaries. To achieve reduced deposition in specific regions a thin wire or ribbon blocking body is placed between source and substrate to partially block vapors from depositing in the region immediately below.

A Stroboscopic Light Source for Experiments in Mechanics

ERIC Educational Resources Information Center

Mayer, V. V.; Varaksina, E. I.

2017-01-01

We propose to attach a small stroboscopic light source to a moving object and connect the source to a pulse generator with the help of insulated thin flexible multi-cored wires. Students can assemble such a device independently in a school laboratory. The device can be used to obtain trajectories with time marks in students' research projects in…

Fabrication of an Aluminum Based Hot Electron Mixer for Terahertz Applications

NASA Technical Reports Server (NTRS)

Echternach, P. M.; LeDuc, H. G.; Skalare, A.; McGrath, W. R.

2000-01-01

Aluminum based diffusion cooled hot electron bolometers (HEB) mixers, predicted to have better noise, bandwidth and to require less LO power than Nb based diffusion cooled HEBs, have been fabricated. Preliminary DC tests were performed. The bolometer elements consisted of short (0.1 to 0.3 micron), narrow (0.08 to 0. 15 micron) and thin (11 nm) aluminum wires connected to large contact pads consisting of a novel trilayer Al/Ti/Au. The patterns were defined by electron beam lithography and the metal deposition involved a double angle process, the Aluminum wires being deposited straight on and the pads being deposited at a 45 degree angle without breaking vacuum. The Al/Ti/Au trilayer was developed to provide a way of making contact between the aluminum wire and the gold antenna. The Titanium layer acts as a diffusion barrier to avoid damage of the Aluminum contact and bolometer wire and to lower the transition temperature of the pads to below that of the bolometer wire. The Au layer avoids the formation of an oxide on the Ti layer and provides good electrical contact to the IF/antenna structure. The resistance of the bolometers as a function of temperature was measured. It is clear that below the transition temperature of the wire (1.8K) but above the transition temperature of the contact pads (0.6K), the proximity effect drives most of the bolometer wire normal, causing a very broad transition. This effect should not affect the performance of the bolometers since they will be operated at a temperature below the TC of the pads. This is evident from the IV characteristics measured at 0.3K. RF characterization tests will begin shortly.

Hysteresis of the Contact Angle of a Meniscus Inside a Capillary with Smooth, Homogeneous Solid Walls.

PubMed

Kuchin, Igor V; Starov, Victor M

2016-05-31

A theory of contact angle hysteresis of a meniscus inside thin capillaries with smooth, homogeneous solid walls is developed in terms of surface forces (disjoining/conjoining pressure isotherm) using a quasi-equilibrium approach. The disjoining/conjoining pressure isotherm includes electrostatic, intermolecular, and structural components. The values of the static receding θr, advancing θa, and equilibrium θe contact angles in thin capillaries were calculated on the basis of the shape of the disjoining/conjoining pressure isotherm. It was shown that both advancing and receding contact angles depend on the capillary radius. The suggested mechanism of the contact angle hysteresis has a direct experimental confirmation: the process of receding is accompanied by the formation of thick β-films on the capillary walls. The effect of the transition from partial to complete wetting in thin capillaries is predicted and analyzed. This effect takes place in very thin capillaries, when the receding contact angle decreases to zero.

Studies on surface morphology and electrical conductivity of PEDOT:PSS thin films in presence of gold nanoparticles

NASA Astrophysics Data System (ADS)

Bhowal, Ashim Chandra; Kundu, Sarathi

2018-04-01

PEDOT:PSS is a water soluble conducting polymer consists of positively charged PEDOT and negatively charged PSS. However, this polymer suffers low conductivity problem which restrict its use. In this paper, electrical conductivity of PEDOT:PSS thin films is improved by using charged gold nanoparticles. The nanoparticles used are synthesized using lysozyme protein. The nanoparticles coated with lysozyme protein possess positive zeta potential. In the presence of gold nanoparticles due to electrostatic interaction between positively charged nanoparticles and negatively charged PSS chains, modification takes place in the surface morphology and electrical behaviors of PEDOT:PSS thin films. The changes in the polymer matrix conformations in the presence of nanoparticles are studied by Fourier transformed Infra-red (FTIR) spectroscopy, whereas the surface morphology of prepared thin films before and after interaction with nanoparticles is investigated through atomic force microscopy (AFM). Four probe method is used to measure the variation of electrical conductivity from I-V characteristics curves.

Carbon Nanospikes Grown on Metal Wires as Microelectrode Sensors for Dopamine

PubMed Central

Zestos, Alexander G.; Yang, Cheng; Jacobs, Christopher B.; Hensley, Dale; Venton, B. Jill

2015-01-01

Carbon nanomaterials are advantageous as electrodes for neurotransmitter detection, but the difficulty of nanomaterials deposition on electrode substrates limits the reproducibility and future applications. In this study, we used plasma enhanced chemical vapor deposition (PECVD) to directly grow a thin layer of carbon nanospikes (CNS) on cylindrical metal substrates. No catalyst is required and the CNS surface coverage is uniform over the cylindrical metal substrate. The CNS growth was characterized on several metallic substrates including tantalum, niobium, palladium, and nickel wires. Using fast-scan cyclic voltammetry (FSCV), bare metal wires could not detect 1 μM dopamine while carbon nanospike coated wires could. The highest sensitivity and optimized S/N ratio was recorded from carbon nanospike-tantalum (CNS-Ta) microwires grown for 7.5 minutes, which had a LOD of 8 ± 2 nM for dopamine with FSCV. CNS-Ta microelectrodes were more reversible and had a smaller ΔEp for dopamine than carbon-fiber microelectrodes, suggesting faster electron transfer kinetics. The kinetics of dopamine redox were adsorption controlled at CNS-Ta microelectrodes and repeated electrochemical measurements displayed stability for up to ten hours in vitro and over a ten day period as well. The oxidation potential was significantly different for ascorbic acid and uric acid compared to dopamine. Growing carbon nanospikes on metal wires is a promising method to produce uniformly-coated, carbon nanostructured cylindrical microelectrodes for sensitive dopamine detection. PMID:26389138

Functional wettability in carbonate reservoirs

DOE PAGES

Brady, Patrick V.; Thyne, Geoffrey

2016-10-11

Oil adsorbs to carbonate reservoirs indirectly through a relatively thick separating water layer, and directly to the surface through a relatively thin intervening water layer. Whereas directly sorbed oil desorbs slowly and incompletely in response to changes in reservoir conditions, indirectly sorbed oil can be rapidly desorbed by changing the chemistry of the separating water layer. The additional recovery might be as much as 30% original oil in place (OOIP) above the ~30% OOIP recovered from carbonates through reservoir depressurization (primary production) and viscous displacement (waterflooding). Electrostatic adhesive forces are the dominant control over carbonate reservoir wettability. A surface complexationmore » model that quantifies electrostatic adhesion accurately predicts oil recovery trends for carbonates. Furthermore, the approach should therefore be useful for estimating initial wettability and designing fluids that improve oil recovery.« less

Measurement of electrostatically formed antennas using photogrammetry and theodolites

NASA Technical Reports Server (NTRS)

Goslee, J. W.; Hinson, W. F.; Kennefick, J. F.; Mihora, D. J.

1984-01-01

An antenna concept is presently being evaluated which has extremely low mass and high surface precision for potential depolyment from the Space Shuttle. This antenna concept derives its reflector surface quality from the application of electrostatic forces to tension and form a thin membrane into the desired concave reflector surface. The Shuttle-deployed antenna would have a diameter of 100 meters and an RMS surface smoothness of 10 to 1 mm for operation at 1 to 10 GHz. NASA Langley Research Center (LaRC) has built, and is currently testing, a subscale (1/20 scale) membrane reflector model of such an antenna. Several surface measurement systems were evaluated as part of the experimental surface measuring efforts. The surface measurement systems are addressed as well as some of the preliminary measurement results.

Determination of the electrostatic potential distribution in Pt/Fe:SrTiO3/Nb:SrTiO3 thin-film structures by electron holography

NASA Astrophysics Data System (ADS)

Marchewka, Astrid; Cooper, David; Lenser, Christian; Menzel, Stephan; Du, Hongchu; Dittmann, Regina; Dunin-Borkowski, Rafal E.; Waser, Rainer

2014-11-01

We determined the electrostatic potential distribution in pristine Pt/Fe:SrTiO3/Nb:SrTiO3 structures by electron holography experiments, revealing the existence of a depletion layer extending into the Nb-doped bottom electrode. Simulations of potential profiles in metal-insulator-metal structures were conducted assuming different types and distributions of dopants. It is found that the presence of acceptor-type dopant concentrations at the Fe:SrTiO3/Nb:SrTiO3 interface with a donor-doped insulating layer provides a good match to the measured profile. Such acceptor-type interface concentrations may be associated with Sr vacancies on the Nb:SrTiO3 side of the bottom interface.

Determination of the electrostatic potential distribution in Pt/Fe:SrTiO₃/Nb:SrTiO₃ thin-film structures by electron holography.

PubMed

Marchewka, Astrid; Cooper, David; Lenser, Christian; Menzel, Stephan; Du, Hongchu; Dittmann, Regina; Dunin-Borkowski, Rafal E; Waser, Rainer

2014-11-10

We determined the electrostatic potential distribution in pristine Pt/Fe:SrTiO3/Nb:SrTiO3 structures by electron holography experiments, revealing the existence of a depletion layer extending into the Nb-doped bottom electrode. Simulations of potential profiles in metal-insulator-metal structures were conducted assuming different types and distributions of dopants. It is found that the presence of acceptor-type dopant concentrations at the Fe:SrTiO3/Nb:SrTiO3 interface with a donor-doped insulating layer provides a good match to the measured profile. Such acceptor-type interface concentrations may be associated with Sr vacancies on the Nb:SrTiO3 side of the bottom interface.

Unidirectional photonic wire laser

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khalatpour, Ali; Reno, John L.; Kherani, Nazir P.

Photonic wire lasers are a new genre of lasers that have a transverse dimension much smaller than the wavelength. Unidirectional emission is highly desirable as most of the laser power will be in the desired direction. Owing to their small lateral dimension relative to the wavelength, however, the mode mostly propagates outside the solid core. Consequently, conventional approaches to attach a highly reflective element to the rear facet, whether a thin film or a distributed Bragg reflector, are not applicable. In this paper, we propose a simple and effective technique to achieve unidirectionality. Terahertz quantum-cascade lasers with distributed feedback (DFB)more » were chosen as the platform of the photonic wire lasers. Unidirectionality is achieved with a power ratio of the forward/backward of about eight, and the power of the forward-emitting laser is increased by a factor of 1.8 compared with a reference bidirectional DFB laser. Finally and furthermore, we achieved a wall plug power efficiency of ~1%.« less

The Fine Wire Technique for Flexor Tenolysis

PubMed Central

Baltodano, Pablo A.; Weinberg, Maxene H.; Whipple, Lauren A.; Gemmiti, Amanda L.; Whipple, Richard E.

2017-01-01

Background: Flexor tenolysis surgery for flexor digitorum profundus and superficialis adhesions is a common procedure performed by hand surgeons. Releasing these adhered tendons can greatly improve hand function and improve quality of life. Recent evidence, however, has shown that the outcomes of tenolysis surgeries are often suboptimal and can result in relapsing adhesions or even tendon ruptures. Methods: This article describes a new technique with potential for reduced complication rates: The Fine Wire Technique for Flexor Tenolysis (FWT). Results: Following FWT, the patient detailed in this article had an excellent recovery of function and no complications: including tendon rupture, infection, hematomas, or any other complications. She reported a major improvement from her preoperative functionality and continues to have this level of success. The wire’s thinness allows for a swift tenolysis. Conclusions: The FWT is a new option available to the hand surgeon associated with good functional results. The wire is readily available to the clinician and is also inexpensive. PMID:29263961

Unidirectional photonic wire laser

DOE PAGES

Khalatpour, Ali; Reno, John L.; Kherani, Nazir P.; ...

2017-08-07

Photonic wire lasers are a new genre of lasers that have a transverse dimension much smaller than the wavelength. Unidirectional emission is highly desirable as most of the laser power will be in the desired direction. Owing to their small lateral dimension relative to the wavelength, however, the mode mostly propagates outside the solid core. Consequently, conventional approaches to attach a highly reflective element to the rear facet, whether a thin film or a distributed Bragg reflector, are not applicable. In this paper, we propose a simple and effective technique to achieve unidirectionality. Terahertz quantum-cascade lasers with distributed feedback (DFB)more » were chosen as the platform of the photonic wire lasers. Unidirectionality is achieved with a power ratio of the forward/backward of about eight, and the power of the forward-emitting laser is increased by a factor of 1.8 compared with a reference bidirectional DFB laser. Finally and furthermore, we achieved a wall plug power efficiency of ~1%.« less

Oxidation of Palladium-Chromium Alloys for High Temperature Applications

NASA Technical Reports Server (NTRS)

Piltch, Nancy D.; Jih-Fen, Lei; Zeller, Mary V.

1994-01-01

An alloy consisting of Pd with 13 wt % Cr is a promising material for high temperature applications. High temperature performance is degraded by the oxidation of the material, which is more severe in the fine wires and thin films used for sensor applications than in the bulk. The present study was undertaken to improve our understanding of the physical and chemical changes occurring at these temperatures and to identify approaches to limit oxidation of the alloy. The alloy was studied in both ribbon and wire forms. Ribbon samples were chosen to examine the role of grain boundaries in the oxidation process because of the convenience of handling for the oxidation studies. Wire samples 25 microns in diameter which are used in resistance strain gages were studied to correlate chemical properties with observed electrical, physical, and structural properties. Overcoating the material with a metallic Cr film did prevent the segregation of Pd to the surface; however, it did not eliminate the oxidation of the alloy.

Vapor-liquid-solid growth of silicon and silicon germanium nanowires

NASA Astrophysics Data System (ADS)

Nimmatoori, Pramod

2009-12-01

Si and Si1-xGex nanowires are promising materials with potential applications in various disciplines of science and technology. Small diameter nanowires can act as model systems to study interesting phenomena such as tunneling that occur in the nanometer regime. Furthermore, technical challenges in fabricating nanoscale size devices from thin films have resulted in interest and research on nanowires. In this perspective, vertical integrated nanowire field effect transistors (VINFETs) fabricated from Si nanowires are promising devices that offer better control on device properties and push the transistor architecture into the third dimension potentially enabling ultra-high transistor density circuits. Transistors fabricated from Si/Si 1-xGex nanowires have also been proposed that can have high carrier mobility. In addition, the Si and Si1-xGe x nanowires have potential to be used in various applications such as sensing, thermoelectrics and solar cells. Despite having considerable potential, the understanding of the vapor-liquid-solid (VLS) mechanism utilized to fabricate these wires is still rudimentary. Hence, the objective of this thesis is to understand the effects of nanoscale size and the role of catalyst that mediates the wire growth on the growth rate of Si and Si1-xGe x nanowires and interfacial abruptness in Si/Si1-xGe x axial heterostructure nanowires. Initially, the growth and structural properties of Si nanowires with tight diameter distribution grown from 10, 20 and 50 nm Au particles dispersed on a polymer-modified substrate was studied. A nanoparticle application process was developed to disperse Au particles on the substrate surface with negligible agglomeration and sufficient density. The growth temperature and SiH4 partial pressure were varied to optimize the growth conditions amenable to VLS growth with smooth wire morphology and negligible Si thin film deposition on wire sidewalls. The Si nanowire growth rate was studied as a function of growth time, temperature, SiH4 partial pressure and wire diameter and discussed in the context of the literature. The wire growth rate was found to increase with wire diameter in agreement with a size-related effect known as the Gibbs-Thomson effect. Subsequently, the effect of P and Sb doping on the growth rate and structural properties of Si nanowires was investigated. A reduction in wire growth rate was observed upon doping, which was pronounced in case of Sb doping, ascribable to P/Sb segregation at the vapor-liquid interface (catalyst surface) and the liquid-solid interface (growth front) that in turn reduces Si incorporation at these interfaces. The second part of thesis was focused on the Si1-xGe x alloy nanowires. The effect of wire diameter and growth conditions on the interfacial abruptness of Si/Si1-xGex heterostructure nanowires was examined. Abrupt interfaces were obtained at smaller wire diameters. However, the growth temperature wasn't found to have much impact on the interfacial abruptness. These results were explained in terms of catalyst effects on the interfacial abruptness. The remaining part of the study was focused on the effect of growth conditions on the growth rate of Si1-x Gex nanowires. It was found that the Si incorporation mechanism was different between Si and Si1-xGex nanowire growth which was ascribed to changes in the gas phase or catalyst composition that can impact the SiH4 decomposition kinetics at the catalyst surface (vapor-liquid interface) and/or Si incorporation at the growth front (liquid-solid interface).

Improved Sensing Coils for SQUIDs

NASA Technical Reports Server (NTRS)

Penanen, Konstantin; Hahn, Inseob; Eom, Byeong Ho

2007-01-01

An improvement in the design and fabrication of sensing coils of superconducting quantum interference device (SQUID) magnetometers has been proposed to increase sensitivity. It has been estimated that, in some cases, it would be possible to increase sensitivity by about half or to reduce measurement time correspondingly. The pertinent aspects of the problems of design and fabrication can be summarized as follows: In general, to increase the sensitivity of a SQUID magnetometer, it is necessary to maximize the magnetic flux enclosed by the sensing coil while minimizing the self-inductance of this coil. It is often beneficial to fabricate the coil from a thicker wire to reduce its self-inductance. Moreover, to optimize the design of the coil with respect to sensitivity, it may be necessary to shape the wire to other than a commonly available circular or square cross-section. On the other hand, it is not practical to use thicker superconducting wire for the entire superconducting circuit, especially if the design of a specific device requires a persistent-current loop enclosing a remotely placed SQUID sensor. It may be possible to bond a thicker sensing-coil wire to thinner superconducting wires leading to a SQUID sensor, but it could be difficult to ensure reliable superconducting connections, especially if the bonded wires are made of different materials. The main idea is to mold the sensing coil in place, to more nearly optimum cross sectional shape, instead of making the coil by winding standard pre-fabricated wire. For this purpose, a thin superconducting wire loop that is an essential part of the SQUID magnetometer would be encapsulated in a form that would serve as a mold. A low-melting-temperature superconducting metal (e.g., indium, tin, or a lead/tin alloy) would be melted into the form, which would be sized and shaped to impart the required cross section to the coil thus formed.

Catalytic igniters and their use to ignite lean hydrogen-air mixtures

DOEpatents

McLean, William J.; Thorne, Lawrence R.; Volponi, Joanne V.

1988-01-01

A catalytic igniter which can ignite a hydrogen-air mixture as lean as 5.5% hydrogen with induction times ranging from 20 s to 400 s, under conditions which may be present during a loss-of-liquid-coolant accident at a light water nuclear reactor comprises (a) a perforate catalytically active substrate, such as a platinum coated ceramic honeycomb or wire mesh screen, through which heated gases produced by oxidation of the mixture can freely flow and (b) a plurality of thin platinum wires mounted in a thermally conductive manner on the substrate and positioned thereon so as to be able to receive heat from the substrate and the heated gases while also in contact with unoxidized gases.

Strain tolerant microfilamentary superconducting wire

DOEpatents

Finnemore, D.K.; Miller, T.A.; Ostenson, J.E.; Schwartzkopf, L.A.; Sanders, S.C.

1993-02-23

A strain tolerant microfilamentary wire capable of carrying superconducting currents is provided comprising a plurality of discontinuous filaments formed from a high temperature superconducting material. The discontinuous filaments have a length at least several orders of magnitude greater than the filament diameter and are sufficiently strong while in an amorphous state to withstand compaction. A normal metal is interposed between and binds the discontinuous filaments to form a normal metal matrix capable of withstanding heat treatment for converting the filaments to a superconducting state. The geometry of the filaments within the normal metal matrix provides substantial filament-to-filament overlap, and the normal metal is sufficiently thin to allow supercurrent transfer between the overlapped discontinuous filaments but is also sufficiently thick to provide strain relief to the filaments.

Production and reactions of silicon atoms in hot wire deposition of amorphous silicon

NASA Astrophysics Data System (ADS)

Zheng, Wengang; Gallagher, Alan

2003-10-01

Decomposing silane and hydrogen molecules on a hot tungsten filament is an alternative method of depositing hydrogenated microcrystal and amorphous Si for thin-film semmiconductor devices. This "hot-wire" method can have significant advantages, such as high film deposition rates. The deposition chemistry involves Si and H atoms released from the filament, followed by their reactions with the vapor and surfaces. To establish these deposition pathways, we measure radicals at the substrate with a home built, threshold ionization mass spectrometer. The design and operation of this mass spectrometer for radical detection, and the behavior of Si atom production and reactions, will be presented. This work is supported by the National Renewable Energy Laboratory, Golden, CO 80401

Contamination control in hybrid microelectronic modules. Part 2: Selection and evaluation of coating materials

NASA Technical Reports Server (NTRS)

Himmel, R. P.

1975-01-01

The selection, test, and evaluation of organic coating materials for contamination control in hybrid circuits is reported. The coatings were evaluated to determine their suitability for use as a conformal coating over the hybrid microcircuit (including chips and wire bonds) inside a hermetically sealed package. Evaluations included ease of coating application and repair and effect on thin film and thick film resistors, beam leads, wire bonds, transistor chips, and capacitor chips. The coatings were also tested for such properties as insulation resistance, voltage breakdown strength, and capability of immobilizing loose particles inside the packages. The selected coatings were found to be electrically, mechanically, and chemically compatible with all components and materials normally used in hybrid microcircuits.

Electronic properties of crystalline Ge1-xSbxTey thin films

NASA Astrophysics Data System (ADS)

Fallica, Roberto; Volpe, Flavio; Longo, Massimo; Wiemer, Claudia; Salicio, Olivier; Abrutis, Adulfas

2012-09-01

Ge1-xSbxTey thin films, grown by metalorganic and hot-wire liquid injection chemical vapor deposition in different crystalline phases, are investigated to determine resistivity, carrier density, and carrier mobility in the 4.2-300 K temperature range. It is found that all these chalcogenides exhibit p-type conduction, high carrier density (>2 . 1020 cm-3), and no carrier freeze-out, regardless of composition. Low-temperature mobility data show that both chemical composition and growth technique affect the defect density and, in turn, the carrier scattering mechanisms. In this regard, charge carrier mobility is analyzed according to semi-empirical scattering models and an interpretation is provided.

Apparatus for determining glowing combustibility of thin fuels

Treesearch

D.C. Jones; A. Broido

1971-01-01

Leaflike samples, approximately 8 cm in diameter, are held at the end of a mechanical arm which reproducibly controls sample movement during the ignition and burn ing process. Glowing combustion is induced by bringing the sample into contact with a small loop in an electrically heated nichrome wire. The ultimate burned-out area is measured 1n an ultraviolet detection...

Tumor Localization Using Radio Frequency Implants

DTIC Science & Technology

2006-09-01

from klystrons and other associated high - energy x-ray generating equipment in the surrounding area. The next logical concept is to use...BAT was developed to visualize the prostate organ before treatment.(34) This system requires that a technologist visually compare images received from ...distance from the transmitter. Since it is a thin wire loop, radiation can be delivered through it with minimal attenuation and

Adaptive Optics System with Deformable Composite Mirror and High Speed, Ultra-Compact Electronics

NASA Astrophysics Data System (ADS)

Chen, Peter C.; Knowles, G. J.; Shea, B. G.

2006-06-01

We report development of a novel adaptive optics system for optical astronomy. Key components are very thin Deformable Mirrors (DM) made of fiber reinforced polymer resins, subminiature PMN-PT actuators, and low power, high bandwidth electronics drive system with compact packaging and minimal wiring. By using specific formulations of fibers, resins, and laminate construction, we are able to fabricate mirror face sheets that are thin (< 2mm), have smooth surfaces and excellent optical shape. The mirrors are not astigmatic and do not develop surface irregularities when cooled. The actuators are small footprint multilayer PMN-PT ceramic devices with large stroke (2- 20 microns), high linearity, low hysteresis, low power, and flat frequency response to >2 KHz. By utilizing QorTek’s proprietary synthetic impendence power supply technology, all the power, control, and signal extraction for many hundreds to 1000s of actuators and sensors can be implemented on a single matrix controller printed circuit board co-mounted with the DM. The matrix controller, in turn requires only a single serial bus interface, thereby obviating the need for massive wiring harnesses. The technology can be scaled up to multi-meter aperture DMs with >100K actuators.

Coaxially gated in-wire thin-film transistors made by template assembly.

PubMed

Kovtyukhova, Nina I; Kelley, Brian K; Mallouk, Thomas E

2004-10-13

Nanowire field effect transistors were prepared by a wet chemical template replication method using anodic aluminum oxide membranes. The membrane pores were first lined with a thin SiO2 layer by the surface sol-gel method. Au, CdS (or CdSe), and Au wire segments were then sequentially electrodeposited within the pores, and the resulting nanowires were released by dissolution of the membrane. Electrofluidic alignment of these nanowires between source and drain leads and evaporation of gold over the central CdS (CdSe) stripe affords a "wrap-around gate" structure. At VDS = -2 V, the Au/CdS/Au devices had an ON/OFF current ratio of 103, a threshold voltage of 2.4 V, and a subthreshold slope of 2.2 V/decade. A 3-fold decrease in the subthreshold slope relative to that of planar nanocrystalline CdSe devices can be attributed to coaxial gating. The control of dimensions afforded by template synthesis should make it possible to reduce the gate dielectric thickness, channel length, and diameter of the semiconductor segment to sublithographic dimensions while retaining the simplicity of the wet chemical synthetic method.

Advanced high temperature static strain sensor development

NASA Technical Reports Server (NTRS)

Hulse, C. O.; Stetson, K. A.; Grant, H. P.; Jameikis, S. M.; Morey, W. W.; Raymondo, P.; Grudkowski, T. W.; Bailey, R. S.

1986-01-01

An examination was made into various techniques to be used to measure static strain in gas turbine liners at temperatures up to 1150 K (1600 F). The methods evaluated included thin film and wire resistive devices, optical fibers, surface acoustic waves, the laser speckle technique with a heterodyne readout, optical surface image and reflective approaches and capacitive devices. A preliminary experimental program to develop a thin film capacitive device was dropped because calculations showed that it would be too sensitive to thermal gradients. In a final evaluation program, the laser speckle technique appeared to work well up to 1150 K when it was used through a relatively stagnant air path. The surface guided acoustic wave approach appeared to be interesting but to require too much development effort for the funds available. Efforts to develop a FeCrAl resistive strain gage system were only partially successful and this part of the effort was finally reduced to a characterization study of the properties of the 25 micron diameter FeCrAl (Kanthal A-1) wire. It was concluded that this particular alloy was not suitable for use as the resistive element in a strain gage above about 1000 K.

Advanced high temperature static strain sensor development

NASA Astrophysics Data System (ADS)

Hulse, C. O.; Stetson, K. A.; Grant, H. P.; Jameikis, S. M.; Morey, W. W.; Raymondo, P.; Grudkowski, T. W.; Bailey, R. S.

1986-08-01

An examination was made into various techniques to be used to measure static strain in gas turbine liners at temperatures up to 1150 K (1600 F). The methods evaluated included thin film and wire resistive devices, optical fibers, surface acoustic waves, the laser speckle technique with a heterodyne readout, optical surface image and reflective approaches and capacitive devices. A preliminary experimental program to develop a thin film capacitive device was dropped because calculations showed that it would be too sensitive to thermal gradients. In a final evaluation program, the laser speckle technique appeared to work well up to 1150 K when it was used through a relatively stagnant air path. The surface guided acoustic wave approach appeared to be interesting but to require too much development effort for the funds available. Efforts to develop a FeCrAl resistive strain gage system were only partially successful and this part of the effort was finally reduced to a characterization study of the properties of the 25 micron diameter FeCrAl (Kanthal A-1) wire. It was concluded that this particular alloy was not suitable for use as the resistive element in a strain gage above about 1000 K.

Multicolor Layer-by-Layer films using weak polyelectrolyte assisted synthesis of silver nanoparticles

NASA Astrophysics Data System (ADS)

Rivero, Pedro Jose; Goicoechea, Javier; Urrutia, Aitor; Matias, Ignacio Raul; Arregui, Francisco Javier

2013-10-01

In the present study, we show that silver nanoparticles (AgNPs) with different shape, aggregation state and color (violet, green, orange) have been successfully incorporated into polyelectrolyte multilayer thin films using the layer-by-layer (LbL) assembly. In order to obtain colored thin films based on AgNPs is necessary to maintain the aggregation state of the nanoparticles, a non-trivial aspect in which this work is focused on. The use of Poly(acrylic acid, sodium salt) (PAA) as a protective agent of the AgNPs is the key element to preserve the aggregation state and makes possible the presence of similar aggregates (shape and size) within the LbLcolored films. This approach based on electrostatic interactions of the polymeric chains and the immobilization of AgNPs with different shape and size into the thin films opens up a new interesting perspective to fabricate multicolornanocomposites based on AgNPs.

Multicolor Layer-by-Layer films using weak polyelectrolyte assisted synthesis of silver nanoparticles

PubMed Central

2013-01-01

In the present study, we show that silver nanoparticles (AgNPs) with different shape, aggregation state and color (violet, green, orange) have been successfully incorporated into polyelectrolyte multilayer thin films using the layer-by-layer (LbL) assembly. In order to obtain colored thin films based on AgNPs is necessary to maintain the aggregation state of the nanoparticles, a non-trivial aspect in which this work is focused on. The use of Poly(acrylic acid, sodium salt) (PAA) as a protective agent of the AgNPs is the key element to preserve the aggregation state and makes possible the presence of similar aggregates (shape and size) within the LbLcolored films. This approach based on electrostatic interactions of the polymeric chains and the immobilization of AgNPs with different shape and size into the thin films opens up a new interesting perspective to fabricate multicolornanocomposites based on AgNPs. PMID:24148227

pH-sensing properties of cascaded long- and short-period fiber grating with poly acrylic acid/poly allylamine hydrochloride thin-film overlays

NASA Astrophysics Data System (ADS)

Yang, Ying

2014-11-01

Based on coupled-mode theory and transfer matrix method, the mode coupling mechanism and the reflection spectral properties of coated cascaded long- and short-period gratings (CLBG) are discussed. The effects of the thin-film parameters (film refractive index and film thickness) on the reflection spectra of the coated CLBG are simulated. By using electrostatic self-assembly method, poly acrylic acid (PAA) and poly allylamine hydrochloride (PAH) multilayer molecular pH-sensitive thin-films are assembled on the surface of the partial corroded CLBG. When the CLBG coated with PAA/PAH films are used to sense pH values, the resonant wavelengths of the CLBG have almost no shift, whereas the resonance peak reflectivities change with pH values. In addition, the sensitivities of the resonance peak reflectivities responding to pH values are improved by an order of magnitude.

Electrochemical Analysis of Conducting Polymer Thin Films

PubMed Central

Vyas, Ritesh N.; Wang, Bin

2010-01-01

Polyelectrolyte multilayers built via the layer-by-layer (LbL) method has been one of the most promising systems in the field of materials science. Layered structures can be constructed by the adsorption of various polyelectrolyte species onto the surface of a solid or liquid material by means of electrostatic interaction. The thickness of the adsorbed layers can be tuned precisely in the nanometer range. Stable, semiconducting thin films are interesting research subjects. We use a conducting polymer, poly(p-phenylene vinylene) (PPV), in the preparation of a stable thin film via the LbL method. Cyclic voltammetry and electrochemical impedance spectroscopy have been used to characterize the ionic conductivity of the PPV multilayer films. The ionic conductivity of the films has been found to be dependent on the polymerization temperature. The film conductivity can be fitted to a modified Randle’s circuit. The circuit equivalent calculations are performed to provide the diffusion coefficient values. PMID:20480052

Reaction Acceleration in Thin Films with Continuous Product Deposition for Organic Synthesis.

PubMed

Wei, Zhenwei; Wleklinski, Michael; Ferreira, Christina; Cooks, R Graham

2017-08-01

Thin film formats are used to study the Claisen-Schmidt base-catalyzed condensation of 6-hydroxy-1-indanone with substituted benzaldehydes and to compare the reaction acceleration relative to the bulk. Relative acceleration factors initially exceeded 10 3 and were on the order of 10 2 at steady state, although the confined volume reaction was not electrostatically driven. Substituent effects were muted compared to those in the corresponding bulk and microdroplet reactions and it is concluded that the rate-limiting step at steady state is reagent transport to the interface. Conditions were found that allowed product deposition from the thin film to occur continuously as the reaction mixture was added and as the solvent evaporated. Yields of 74 % and production rates of 98 mg h -1 were reached in a very simple experimental system that could be multiplexed to greater scales. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Highly sensitive graphene biosensor by monomolecular self-assembly of receptors on graphene surface

NASA Astrophysics Data System (ADS)

Kim, Ji Eun; No, Young Hyun; Kim, Joo Nam; Shin, Yong Seon; Kang, Won Tae; Kim, Young Rae; Kim, Kun Nyun; Kim, Yong Ho; Yu, Woo Jong

2017-05-01

Graphene has attracted a great deal of interest for applications in bio-sensing devices because of its ultra-thin structure, which enables strong electrostatic coupling with target molecules, and its excellent electrical mobility promising for ultra-fast sensing speeds. However, thickly stacked receptors on the graphene's surface interrupts electrostatic coupling between graphene and charged biomolecules, which can reduce the sensitivity of graphene biosensors. Here, we report a highly sensitive graphene biosensor by the monomolecular self-assembly of designed peptide protein receptors. The graphene channel was non-covalently functionalized using peptide protein receptors via the π-π interaction along the graphene's Bravais lattice, allowing ultra-thin monomolecular self-assembly through the graphene lattice. In thickness dependent characterization, a graphene sensor with a monomolecular receptor (thickness less than 3 nm) showed five times higher sensitivity and three times higher voltage shifts than graphene sensors with thick receptor stacks (thicknesses greater than 20 nm), which is attributed to excellent gate coupling between graphene and streptavidin via an ultrathin receptor insulator. In addition to having a fast-inherent response time (less than 0.6 s) based on fast binding speed between biotin and streptavidin, our graphene biosensor is a promising platform for highly sensitive real-time monitoring of biomolecules with high spatiotemporal resolution.

Rethinking Use of the OML Model in Electric Sail Development

NASA Technical Reports Server (NTRS)

Stone, Nobie H.

2016-01-01

In 1924, Irvin Langmuir and H. M. Mott-Smith published a theoretical model for the complex plasma sheath phenomenon in which they identified some very special cases which greatly simplified the sheath and allowed a closed solution to the problem. The most widely used application is for an electrostatic, or "Langmuir," probe in laboratory plasma. Although the Langmuir probe is physically simple (a biased wire) the theory describing its functional behavior and its current-voltage characteristic is extremely complex and, accordingly, a number of assumptions and approximations are used in the LMS model. These simplifications, correspondingly, place limits on the model's range of application. Adapting the LMS model to real-life conditions is the subject of numerous papers and dissertations. The Orbit-Motion Limited (OML) model that is widely used today is one of these adaptions that is a convenient means of calculating sheath effects. Since the Langmuir probe is a simple biased wire immersed in plasma, it is particularly tempting to use the OML equation in calculating the characteristics of the long, highly biased wires of an Electric Sail in the solar wind plasma. However, in order to arrive at the OML equation, a number of additional simplifying assumptions and approximations (beyond those made by Langmuir-Mott-Smith) are necessary. The OML equation is a good approximation when all conditions are met, but it would appear that the Electric Sail problem lies outside of the limits of applicability.

Deep Charging Evaluation of Satellite Power and Communication System Components

NASA Technical Reports Server (NTRS)

Schneider, T. A.; Vaughn, J. A.; Chu, B.; Wong, F.; Gardiner, G.; Wright, K. H.; Phillips, B.

2016-01-01

Deep charging, in contrast to surface charging, focuses on electron penetration deep into insulating materials applied over conductors. A classic example of this scenario is an insulated wire. Deep charging can pose a threat to material integrity, and to sensitive electronics, when it gives rise to an electrostatic discharge or arc. With the advent of Electric Orbit Raising, which requires spiraling through Earth's radiation belts, satellites are subjected to high energy electron environments which they normally would not encounter. Beyond Earth orbit, missions to Jupiter and Saturn face deep charging concerns due to the high energy radiation environments. While predictions can be made about charging in insulating materials, it is difficult to extend those predictions to complicated geometries, such as the case of an insulating coating around a small wire, or a non-uniform silicone grouting on a bus bar. Therefore, to conclusively determine the susceptibility of a system to arcs from deep charging, experimental investigations must be carried out. This paper will describe the evaluation carried out by NASA's Marshall Space Flight Center on subscale flight-like samples developed by Space Systems/Loral, LLC. Specifically, deep charging evaluations of solar array wire coupons, a photovoltaic cell coupon, and a coaxial microwave transmission cable, will be discussed. The results of each evaluation will be benchmarked against control sample tests, as well as typical power system levels, to show no significant deep charging threat existed for this set of samples under the conditions tested.

Thin and long silver nanowires self-assembled in ionic liquids as a soft template: electrical and optical properties

NASA Astrophysics Data System (ADS)

Chang, Min-Hwa; Cho, Hyun-Ah; Kim, Youn-Soo; Lee, Eun-Jong; Kim, Jin-Yeol

2014-07-01

Thin and long silver nanowires were successfully synthesized using the polyvinylpyrrolidone (PVP)-assisted polyol method in the presence of ionic liquids, tetrapropylammonium chloride and tetrapropylammonium bromide, which served as soft template salts. The first step involved the formation of Ag nanoparticles with a diameter of 40 to 50 nm through the reduction of silver nitrate. At the growing stage, the Ag nanoparticles were converted into thin and long one-dimensional wires, with uniform diameters of 30 ± 3 nm and lengths of up to 50 μm. These Ag nanowires showed an electrical conductivity of 0.3 × 105 S/cm, while the sheet resistance of a two-dimensional percolating Ag nanowire network exhibited a value of 20 Ω/sq with an optical transmittance of 93% and a low haze value.

New high-resolution electrostatic ion mass analyzer using time of flight

NASA Technical Reports Server (NTRS)

Hamilton, D. C.; Gloeckler, G.; Ipavich, F. M.; Lundgren, R. A.; Sheldon, R. B.

1990-01-01

The design of a high-resolution ion-mass analyzer is described, which is based on an accurate measurement of the time of flight (TOF) of ions within a region configured to produce a harmonic potential. In this device, the TOF, which is independent of ion energy, is determined from a start pulse from secondary electrons produced when the ion passes through a thin carbon foil at the entrance of the TOF region and at a stop pulse from the ion striking a microchannel plate upon exciting the region. A laboratory prototype instrument called 'VMASS' was built and was tested at the Goddard Space Flight Center electrostatic accelerator, showing a good mass resolution of the instrument. Sensors of the VMASS type will form part of the WIND Solar Wind and Suprathermal Ion experiment, the Soho mission, and the Advanced Composition Explorer.

X-Ray Absorption Microspectroscopy with Electrostatic Force Microscopy and its Application to Chemical States Mapping

NASA Astrophysics Data System (ADS)

Ishii, M.; Rigopoulos, N.; Poolton, N. R. J.; Hamilton, B.

2007-02-01

A new technique named X-EFM that measures the x-ray absorption fine structure (XAFS) of nanometer objects was developed. In X-EFM, electrostatic force microscopy (EFM) is used as an x-ray absorption detector, and photoionization induced by x-ray absorption of surface electron trapping sites is detected by EFM. An EFM signal with respect to x-ray photon energy provides the XAFS spectra of the trapping sites. We adopted X-EFM to observe Si oxide thin films. An edge jump shift intrinsic to the X-EFM spectrum was found, and it was explained with a model where an electric field between the trapping site and probe deepens the energy level of the inner-shell. A scanning probe under x-rays with fixed photon energy provided the chemical state mapping on the surface.

Thin film thermocouples for thermoelectric characterization of nanostructured materials

NASA Astrophysics Data System (ADS)

Grayson, Matthew; Zhou, Chuanle; Varrenti, Andrew; Chyung, Seung Hye; Long, Jieyi; Memik, Seda

2011-03-01

The increased use of nanostructured materials as thermoelectrics requires reliable and accurate characterization of the anisotropic thermal coefficients of small structures, such as superlattices and quantum wire networks. Thin evaporated metal films can be used to create thermocouples with a very small thermal mass and low thermal conductivity, in order to measure thermal gradients on nanostructures and thereby measure the thermal conductivity and the Seebeck coefficient of the nanostructure. In this work we confirm the known result that thin metal films have lower Seebeck coefficients than bulk metals, and we also calibrate the Seebeck coefficient of a thin-film Ni/Cr thermocouple with 50 nm thickness, showing it to have about 1/4 the bulk value. We demonstrate reproducibility of this thin-filmSeebeck coefficient on multiple substrates, and we show that this coefficient does, in fact, change as a function of film thickness. We will discuss prototype measurement designs and preliminary work as to how these thin films can be used to study both Seebeck coefficients and thermal conductivities of superlattices in various geometries. The same technology can in principle be used on integrated circuits for thermal mapping, under the name ``Integrated On-Chip Thermocouple Array'' (IOTA).

Evaporation system and method for gas jet deposition of thin film materials

DOEpatents

Schmitt, J.J.; Halpern, B.L.

1994-10-18

A method and apparatus are disclosed for depositing thin films of materials such as metals, oxides and nitrides at low temperature relies on a supersonic free jet of inert carrier gas to transport vapor species generated from an evaporation source to the surface of a substrate. Film deposition vapors are generated from solid film precursor materials, including those in the form of wires or powders. The vapor from these sources is carried downstream in a low pressure supersonic jet of inert gas to the surface of a substrate where the vapors deposit to form a thin film. A reactant gas can be introduced into the gas jet to form a reaction product with the evaporated material. The substrate can be moved from the gas jet past a gas jet containing a reactant gas in which a discharge has been generated, the speed of movement being sufficient to form a thin film which is chemically composed of the evaporated material and reactant gases. 8 figs.

Evaporation system and method for gas jet deposition of thin film materials

DOEpatents

Schmitt, Jerome J.; Halpern, Bret L.

1994-01-01

A method and apparatus for depositing thin films of materials such as metals, oxides and nitrides at low temperature relies on a supersonic free jet of inert carrier gas to transport vapor species generated from an evaporation source to the surface of a substrate. Film deposition vapors are generated from solid film precursor materials, including those in the form of wires or powders. The vapor from these sources is carried downstream in a low pressure supersonic jet of inert gas to the surface of a substrate where the vapors deposit to form a thin film. A reactant gas can be introduced into the gas jet to form a reaction product with the evaporated material. The substrate can be moved from the gas jet past a gas jet containing a reactant gas in which a discharge has been generated, the speed of movement being sufficient to form a thin film which is chemically composed of the evaporated material and reactant gases.

Metallization of a Rashba wire by a superconducting layer in the strong-proximity regime

NASA Astrophysics Data System (ADS)

Reeg, Christopher; Loss, Daniel; Klinovaja, Jelena

2018-04-01

Semiconducting quantum wires defined within two-dimensional electron gases and strongly coupled to thin superconducting layers have been extensively explored in recent experiments as promising platforms to host Majorana bound states. We study numerically such a geometry, consisting of a quasi-one-dimensional wire coupled to a disordered three-dimensional superconducting layer. We find that, in the strong-coupling limit of a sizable proximity-induced superconducting gap, all transverse subbands of the wire are significantly shifted in energy relative to the chemical potential of the wire. For the lowest subband, this band shift is comparable in magnitude to the spacing between quantized levels that arises due to the finite thickness of the superconductor (which typically is ˜500 meV for a 10-nm-thick layer of aluminum); in higher subbands, the band shift is much larger. Additionally, we show that the width of the system, which is usually much larger than the thickness, and moderate disorder within the superconductor have almost no impact on the induced gap or band shift. We provide a detailed discussion of the ramifications of our results, arguing that a huge band shift and significant renormalization of semiconducting material parameters in the strong-coupling limit make it challenging to realize a topological phase in such a setup, as the strong coupling to the superconductor essentially metallizes the semiconductor. This metallization of the semiconductor can be tested experimentally through the measurement of the band shift.

Geometry characteristics modeling and process optimization in coaxial laser inside wire cladding

NASA Astrophysics Data System (ADS)

Shi, Jianjun; Zhu, Ping; Fu, Geyan; Shi, Shihong

2018-05-01

Coaxial laser inside wire cladding method is very promising as it has a very high efficiency and a consistent interaction between the laser and wire. In this paper, the energy and mass conservation law, and the regression algorithm are used together for establishing the mathematical models to study the relationship between the layer geometry characteristics (width, height and cross section area) and process parameters (laser power, scanning velocity and wire feeding speed). At the selected parameter ranges, the predicted values from the models are compared with the experimental measured results, and there is minor error existing, but they reflect the same regularity. From the models, it is seen the width of the cladding layer is proportional to both the laser power and wire feeding speed, while it firstly increases and then decreases with the increasing of the scanning velocity. The height of the cladding layer is proportional to the scanning velocity and feeding speed and inversely proportional to the laser power. The cross section area increases with the increasing of feeding speed and decreasing of scanning velocity. By using the mathematical models, the geometry characteristics of the cladding layer can be predicted by the known process parameters. Conversely, the process parameters can be calculated by the targeted geometry characteristics. The models are also suitable for multi-layer forming process. By using the optimized process parameters calculated from the models, a 45 mm-high thin-wall part is formed with smooth side surfaces.

Carbon nanospikes grown on metal wires as microelectrode sensors for dopamine

DOE PAGES

Zestos, Alexander G.; Yang, Cheng; Jacobs, Christopher B.; ...

2015-09-14

Carbon nanomaterials are advantageous as electrodes for neurotransmitter detection, but the difficulty of nanomaterials deposition on electrode substrates limits the reproducibility and future applications. In our study, we used plasma enhanced chemical vapor deposition (PECVD) to directly grow a thin layer of carbon nanospikes (CNS) on cylindrical metal substrates. No catalyst is required and the CNS surface coverage is uniform over the cylindrical metal substrate. We characterized the CNS growth on several metallic substrates including tantalum, niobium, palladium, and nickel wires. Using fast-scan cyclic voltammetry (FSCV), bare metal wires could not detect 1 mu M dopamine while carbon nanospike coatedmore » wires could. Moreover, the highest sensitivity and optimized S/N ratio was recorded from carbon nanospike-tantalum (CNS-Ta) microwires grown for 7.5 minutes, which had a LOD of 8 +/- 2 nM for dopamine with FSCV. CNS-Ta microelectrodes were more reversible and had a smaller Delta E-p for dopamine than carbon-fiber microelectrodes, suggesting faster electron transfer kinetics. The kinetics of dopamine redox were adsorption controlled at CNS-Ta microelectrodes and repeated electrochemical measurements displayed stability for up to ten hours in vitro and over a ten day period as well. The oxidation potential was significantly different for ascorbic acid and uric acid compared to dopamine. Finally, growing carbon nanospikes on metal wires is a promising method to produce uniformly-coated, carbon nanostructured cylindrical microelectrodes for sensitive dopamine detection.« less

Sampling and analysis of aircraft engine cold start particles and demonstration of an electrostatic personal particle sampler.

PubMed

Armendariz, Alfredo; Leith, David; Boundy, Maryanne; Goodman, Randall; Smith, Les; Carlton, Gary

2003-01-01

Aircraft engines emit an aerosol plume during startup in extremely cold weather that can drift into areas occupied by flightline ground crews. This study tested a personal sampler used to assess exposure to particles in the plume under challenging field conditions. Area and personal samples were taken at two U.S. Air Force (USAF) flightlines during the winter months. Small tube-and-wire electrostatic precipitators (ESPs) were mounted on a stationary stand positioned behind the engines to sample the exhaust. Other ESPs were worn by ground crews to sample breathing zone concentrations. In addition, an aerodynamic particle sizer 3320 (APS) was used to determine the size distribution of the particles. Samples collected with the ESP were solvent extracted and analyzed with gas chromatography-mass spectrometry. Results indicated that the plume consisted of up to 75 mg/m(3) of unburned jet fuel particles. The APS showed that nearly the entire particle mass was respirable, because the plumes had mass median diameters less than 2 micro m. These tests demonstrated that the ESP could be used at cold USAF flightlines to perform exposure assessments to the cold start particles.

Effect of in situ electric-field-assisted growth on antiphase boundaries in epitaxial Fe3O4 thin films on MgO

NASA Astrophysics Data System (ADS)

Kumar, Ankit; Wetterskog, Erik; Lewin, Erik; Tai, Cheuk-Wai; Akansel, Serkan; Husain, Sajid; Edvinsson, Tomas; Brucas, Rimantas; Chaudhary, Sujeet; Svedlindh, Peter

2018-05-01

Antiphase boundaries (APBs) normally form as a consequence of the initial growth conditions in all spinel ferrite thin films. These boundaries result from the intrinsic nucleation and growth mechanism, and are observed as regions where the periodicity of the crystalline lattice is disrupted. The presence of APBs in epitaxial films of the inverse spinel Fe3O4 alters their electronic and magnetic properties due to strong antiferromagnetic (AF) interactions across these boundaries. We explore the effect of using in-plane in situ electric-field-assisted growth on the formation of APBs in heteroepitaxial Fe3O4 (100)/MgO(100) thin films. The electric-field-assisted growth is found to reduce the AF interactions across APBs and, as a consequence, APB-free thin-film-like properties are obtained, which have been probed by electronic, magnetic, and structural characterization. The electric field plays a critical role in controlling the density of APBs during the nucleation process by providing an electrostatic force acting on adatoms and therefore changing their kinetics. This innovative technique can be employed to grow epitaxial spinel thin films with controlled AF interactions across APBs.

Static Aeroelasticity in Combat Aircraft.

DTIC Science & Technology

1986-01-01

stiffness scaled beam machined along a predicted elastic axis, and load iola- tion cuts forward and aft of the beam, has proved to be most successful...aircraft components. Many papers deal with the activities in the field of structural optimization.’ 4sing fiber composites , a new design technique...Supersonic Design Composite Structures Fly - by - Wire Thin Profiles Aeroelastic Tailoring Unstable Aircraft V Variable Camber Lght Weight Pilot Handling

Wave Propagation and Stability for Finite Difference Schemes.

DTIC Science & Technology

1982-05-01

56 C -- t" natually associated with a signal zaa’. and thin spced approaches C in the limit way tc nake this motion quantitative wnould be to...ronnqienee of tlie identiewily teen reflection the haani~dary Let U~ ,Ohey rirly 1 i 1 irrirt wire , I.e.b, i at dsta at yr’ 1 ene Iiir.t That is. the IF 2

Control Demonstration of a Thin Deformable In-Plane Actuated Mirror

DTIC Science & Technology

2006-03-01

where a four-quadrant electrode grid sitting behind a pre-shaped membrane mirror uses electrostatic forces to deform the surface. Any manufacturing...to receive the Wavescope data due to its MATLAB and Simulink capa- bilities. The dSPACE computer system is stocked with a UART (Universal Asynchronous...cations,” SPIE Smart Structures and Materials Symposium, EAPAD Conference, Vol. 5051-45 (2003). 6. Bennet, H. E. and others, . “Development of

Explosive Testing of Class 1.3 Rocket Booster Propellant

DTIC Science & Technology

1994-08-01

molds were lined with 0.025 mm (0.001 in.) Velostat conductive plastic sheet and sprayed with a mold release that dried leaving fine Teflon powder... Velostat sheet (0.03 in.) was wrapped around the sample and grounded for improved electrostatic safety. Similar to previous cylinder tests, the...layer of thin Velostat plastic sheet, its contribution to camera viewing distortion of the flame front is not known. Overall, an average velocity over

Boundary condition for Ginzburg-Landau theory of superconducting layers

NASA Astrophysics Data System (ADS)

Koláček, Jan; Lipavský, Pavel; Morawetz, Klaus; Brandt, Ernst Helmut

2009-05-01

Electrostatic charging changes the critical temperature of superconducting thin layers. To understand the basic mechanism, it is possible to use the Ginzburg-Landau theory with the boundary condition derived by de Gennes from the BCS theory. Here we show that a similar boundary condition can be obtained from the principle of minimum free energy. We compare the two boundary conditions and use the Budd-Vannimenus theorem as a test of approximations.

Surface engineering of zirconium particles by molecular layer deposition: Significantly enhanced electrostatic safety at minimum loss of the energy density

NASA Astrophysics Data System (ADS)

Qin, Lijun; Yan, Ning; Hao, Haixia; An, Ting; Zhao, Fengqi; Feng, Hao

2018-04-01

Because of its high volumetric heat of oxidation, Zr powder is a promising high energy fuel/additive for rocket propellants. However, the application of Zr powder is restricted by its ultra-high electrostatic discharge sensitivity, which poses great hazards for handling, transportation and utilization of this material. By performing molecular layer deposition of polyimide using 1,2,4,5-benzenetetracarboxylic anhydride and ethylenediamine as the precursors, Zr particles can be uniformly encapsulated by thin layers of the polymer. The thicknesses of the encapsulation layers can be precisely controlled by adjusting the number of deposition cycle. High temperature annealing converts the polymer layer into a carbon coating. Results of thermal analyses reveal that the polymer or carbon coatings have little negative effect on the energy release process of the Zr powder. By varying the thickness of the polyimide or carbon coating, electrostatic discharge sensitivity of the Zr powder can be tuned in a wide range and its uncontrolled ignition hazard can be virtually eliminated. This research demonstrates the great potential of molecular layer deposition in effectively modifying the surface properties of highly reactive metal based energetic materials with minimum sacrifices of their energy densities.

Fabrication of Quench Condensed Thin Films Using an Integrated MEMS Fab on a Chip

NASA Astrophysics Data System (ADS)

Lally, Richard; Reeves, Jeremy; Stark, Thomas; Barrett, Lawrence; Bishop, David

Atomic calligraphy is a microelectromechanical systems (MEMS)-based dynamic stencil nanolithography technique. Integrating MEMS devices into a bonded stacked array of three die provides a unique platform for conducting quench condensed thin film mesoscopic experiments. The atomic calligraphy Fab on a Chip process incorporates metal film sources, electrostatic comb driven stencil plate, mass sensor, temperature sensor, and target surface into one multi-die assembly. Three separate die are created using the PolyMUMPs process and are flip-chip bonded together. A die containing joule heated sources must be prepared with metal for evaporation prior to assembly. A backside etch of the middle/central die exposes the moveable stencil plate allowing the flux to pass through the stencil from the source die to the target die. The chip assembly is mounted in a cryogenic system at ultra-high vacuum for depositing extremely thin films down to single layers of atoms across targeted electrodes. Experiments such as the effect of thin film alloys or added impurities on their superconductivity can be measured in situ with this process.

Observation of `third sound' in superfluid 3He

NASA Astrophysics Data System (ADS)

Schechter, A. M. R.; Simmonds, R. W.; Packard, R. E.; Davis, J. C.

1998-12-01

Waves on the surface of a fluid provide a powerful tool for studying the fluid itself and the surrounding physical environment. For example, the wave speed is determined by the force per unit mass at the surface, and by the depth of the fluid: the decreasing speed of ocean waves as they approach the shore reveals the changing depth of the sea and the strength of gravity. Other examples include propagating waves in neutron-star oceans and on the surface of levitating liquid drops. Although gravity is a common restoring force, others exist, including the electrostatic force which causes a thin liquid film to adhere to a solid. Usually surface waves cannot occur on such thin films because viscosity inhibits their motion. However, in the special case of thin films of superfluid 4He, surface waves do exist and are called `third sound'. Here we report the detection of similar surface waves in thin films of superfluid 3He. We describe studies of the speed of these waves, the properties of the surface force, and the film's superfluid density.

Method for producing strain tolerant multifilamentary oxide superconducting wire

DOEpatents

Finnemore, D.K.; Miller, T.A.; Ostenson, J.E.; Schwartzkopf, L.A.; Sanders, S.C.

1994-07-19

A strain tolerant multifilamentary wire capable of carrying superconducting currents is provided comprising a plurality of discontinuous filaments formed from a high temperature superconducting material. The discontinuous filaments have a length at least several orders of magnitude greater than the filament diameter and are sufficiently strong while in an amorphous state to withstand compaction. A normal metal is interposed between and binds the discontinuous filaments to form a normal metal matrix capable of withstanding heat treatment for converting the filaments to a superconducting state. The geometry of the filaments within the normal metal matrix provides substantial filament-to-filament overlap, and the normal metal is sufficiently thin to allow supercurrent transfer between the overlapped discontinuous filaments but is also sufficiently thick to provide strain relief to the filaments. 6 figs.

Method for producing strain tolerant multifilamentary oxide superconducting wire

DOEpatents

Finnemore, Douglas K.; Miller, Theodore A.; Ostenson, Jerome E.; Schwartzkopf, Louis A.; Sanders, Steven C.

1994-07-19

A strain tolerant multifilamentary wire capable of carrying superconducting currents is provided comprising a plurality of discontinuous filaments formed from a high temperature superconducting material. The discontinuous filaments have a length at least several orders of magnitude greater than the filament diameter and are sufficiently strong while in an amorphous state to withstand compaction. A normal metal is interposed between and binds the discontinuous filaments to form a normal metal matrix capable of withstanding heat treatment for converting the filaments to a superconducting state. The geometry of the filaments within the normal metal matrix provides substantial filament-to-filament overlap, and the normal metal is sufficiently thin to allow supercurrent transfer between the overlapped discontinuous filaments but is also sufficiently thick to provide strain relief to the filaments.

The destabilization of an initially thick liquid sheet edge

NASA Astrophysics Data System (ADS)

Lhuissier, Henri; Villermaux, Emmanuel

2011-09-01

By forcing the sudden dewetting of a free soap film attached on one edge to a straight solid wire, we study the recession and subsequent destabilization of its free edge. The newly formed rim bordering the sheet is initially thicker than the film to which it is attached, because of the Plateau border preexisting on the wire. The initial condition is thus that of an immobile massive toroidal rim connected to a thin liquid film of thickness h. The terminal Taylor-Culick receding velocity V =√2σ/ρh , where σ and ρ are the liquid surface tension and density, respectively, is only reached after a transient acceleration period which promotes the rim destabilization. The selected wavelength and associated growth time coincide with those of an inertial instability driven by surface tension.

Development of an Electrostatic Precipitator to Remove Martian Atmospheric Dust from ISRU Gas Intakes During Planetary Exploration Missions

NASA Technical Reports Server (NTRS)

Clements, J. Sidney; Thompson, Samuel M.; Cox, Nathan D.; Johansen, Michael R.; Williams, Blakeley S.; Hogue, Michael D.; Lowder, M. Loraine; Calle, Carlos I.

2011-01-01

Manned exploration missions to Mars will need dependable in situ resource utilization (ISRU) for the production of oxygen and other commodities. One of these resources is the Martian atmosphere itself, which is composed of carbon dioxide (95.3%), nitrogen (2.7%), argon (1.6%), oxygen (0.13%), carbon monoxide (0.07%), and water vapor (0.03%), as well as other trace gases. However, the Martian atmosphere also contains relatively large amounts of dust, uploaded by frequent dust devils and high Winds. To make this gas usable for oxygen extraction in specialized chambers requires the removal of most of the dust. An electrostatic precipitator (ESP) system is an obvious choice. But with an atmospheric pressure just one-hundredth of Earth's, electrical breakdown at low voltages makes the implementation of the electrostatic precipitator technology very challenging. Ion mobility, drag forces, dust particle charging, and migration velocity are also affected because the low gas pressure results in molecular mean free paths that are approximately one hundred times longer than those at Earth .atmospheric pressure. We report here on our efforts to develop this technology at the Kennedy Space Center, using gases with approximately the same composition as the Martian atmosphere in a vacuum chamber at 9 mbars, the atmospheric pressure on Mars. We also present I-V curves and large particle charging data for various versions of wire-cylinder and rod-cylinder geometry ESPs. Preliminary results suggest that use of an ESP for dust collection on Mars may be feasible, but further testing with Martian dust simulant is required.

Dynamic control of laser driven proton beams by exploiting self-generated, ultrashort electromagnetic pulses

NASA Astrophysics Data System (ADS)

Kar, S.; Ahmed, H.; Nersisyan, G.; Brauckmann, S.; Hanton, F.; Giesecke, A. L.; Naughton, K.; Willi, O.; Lewis, C. L. S.; Borghesi, M.

2016-05-01

As part of the ultrafast charge dynamics initiated by high intensity laser irradiations of solid targets, high amplitude EM pulses propagate away from the interaction point and are transported along any stalks and wires attached to the target. The propagation of these high amplitude pulses along a thin wire connected to a laser irradiated target was diagnosed via the proton radiography technique, measuring a pulse duration of ˜20 ps and a pulse velocity close to the speed of light. The strong electric field associated with the EM pulse can be exploited for controlling dynamically the proton beams produced from a laser-driven source. Chromatic divergence control of broadband laser driven protons (upto 75% reduction in divergence of >5 MeV protons) was obtained by winding the supporting wire around the proton beam axis to create a helical coil structure. In addition to providing focussing and energy selection, the technique has the potential to post-accelerate the transiting protons by the longitudinal component of the curved electric field lines produced by the helical coil lens.

Dynamic control of laser driven proton beams by exploiting self-generated, ultrashort electromagnetic pulses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kar, S., E-mail: s.kar@qub.ac.uk; Ahmed, H.; Nersisyan, G.

As part of the ultrafast charge dynamics initiated by high intensity laser irradiations of solid targets, high amplitude EM pulses propagate away from the interaction point and are transported along any stalks and wires attached to the target. The propagation of these high amplitude pulses along a thin wire connected to a laser irradiated target was diagnosed via the proton radiography technique, measuring a pulse duration of ∼20 ps and a pulse velocity close to the speed of light. The strong electric field associated with the EM pulse can be exploited for controlling dynamically the proton beams produced from amore » laser-driven source. Chromatic divergence control of broadband laser driven protons (upto 75% reduction in divergence of >5 MeV protons) was obtained by winding the supporting wire around the proton beam axis to create a helical coil structure. In addition to providing focussing and energy selection, the technique has the potential to post-accelerate the transiting protons by the longitudinal component of the curved electric field lines produced by the helical coil lens.« less

[Direct electric conduction glove for laparoscopic surgical instruments. Preliminary results of a prototype].

PubMed

Gentilli, Sergio; Morgandoa, Andrea; Velardocchia, Mauro; Pessione, Silvia; Pizzorno, Chiara

2007-01-01

The authors present their prototype of a system for electrical conduction in direct contact with laparoscopic tools, devised, designed and produced by them at the Politecnico di Torino Department of Mechanical Engineering. The system consists of a two-sided plate, one side being a non-conducting adhesive surface to stick to the surgical glove and the other a thin, flexible conductor shell. The authors used the instrument with surgical tools with metal handles during 4 laparoscopic procedures. Nowadays the method commonly used to electrify laparoscopic tools is by using a wire plugged to a fixed conducting point on the instrument. The prototype described here was devised and produced to avoid some of the awkwardness encountered during the numerous manoeuvres required to connect and disconnect the wire at the time of surgical intervention. This device permits the direct transfer (by contact) of electrical energy from the wire to surgical tools. The advantage is greater rapidity in changing surgical tools, with the possibility of immediately obtaining an electrified instrument in the surgeon's hand.

Exfoliated YBCO filaments for second-generation superconducting cable

NASA Astrophysics Data System (ADS)

Solovyov, Vyacheslav; Farrell, Paul

2017-01-01

The second-generation high temperature superconductor (2G HTS) wire is the most promising conductor for high-field magnets such as accelerator dipoles and compact fusion devices. The key element of the wire is a thin Y1Ba2Cu3O7 (YBCO) layer deposited on a flexible metal substrate. The substrate, which becomes incorporated in the 2G conductor, reduces the electrical and mechanical performance of the wire. This is a process that exfoliates the YBCO layer from the substrate while retaining the critical current density of the superconductor. Ten-centimeter long coupons of exfoliated YBCO layers were manufactured, and detailed structural, electrical, and mechanical characterization were reported. After exfoliation, the YBCO layer was supported by a 75 μm thick stainless steel foil, which makes for a compact, mechanically stronger, and inexpensive conductor. The critical current density of the filaments was measured at both 77 K and 4.2 K. The exfoliated YBCO retained 90% of the original critical current. Similarly, tests in an external magnetic field at 4.2 K confirmed that the pinning strength of the YBCO layer was also retained following exfoliation.

Testing sTGC with small angle wire edges for the ATLAS new small wheel muon detector upgrade

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roth, Itamar; Klier, Amit; Duchovni, Ehud

The LHC upgrade scheduled for 2018 is expected to significantly increase the accelerator's luminosity, and as a result the radiation background rates in the ATLAS Muon Spectrometer will increase too. Some of its components will have to be replaced in order to cope with these high rates. Newly designed small-strip Thin Gap chambers (sTGC) will replace them at the small wheel region. One of the differences between the sTGC and the currently used TGC is the alignment of the wires along the azimuthal direction. As a result, the outermost wires approach the detector's edge with a small angle. Such amore » configuration may be a cause for various problems. Two small dedicated chambers were built and tested in order to study possible edge effects that may arise from the new configuration. The sTGC appears to be stable and no spark have been observed, yet some differences in the detector response near the edge is seen and further studies should be carried out. (authors)« less

Electrical properties of sub-100 nm SiGe nanowires

NASA Astrophysics Data System (ADS)

Hamawandi, B.; Noroozi, M.; Jayakumar, G.; Ergül, A.; Zahmatkesh, K.; Toprak, M. S.; Radamson, H. H.

2016-10-01

In this study, the electrical properties of SiGe nanowires in terms of process and fabrication integrity, measurement reliability, width scaling, and doping levels were investigated. Nanowires were fabricated on SiGe-on oxide (SGOI) wafers with thickness of 52 nm and Ge content of 47%. The first group of SiGe wires was initially formed by using conventional I-line lithography and then their size was longitudinally reduced by cutting with a focused ion beam (FIB) to any desired nanometer range down to 60 nm. The other nanowire group was manufactured directly to a chosen nanometer level by using sidewall transfer lithography (STL). It has been shown that the FIB fabrication process allows manipulation of the line width and doping level of nanowires using Ga atoms. The resistance of wires thinned by FIB was 10 times lower than STL wires which shows the possible dependency of electrical behavior on fabrication method. Project support by the Swedish Foundation for Strategic Research “SSF” (No. EM-011-0002) and the Scientific and Technological Research Council of Turkey (No. TÜBİTAK).

Variable field-of-view visible and near-infrared polarization compound-eye endoscope.

PubMed

Kagawa, K; Shogenji, R; Tanaka, E; Yamada, K; Kawahito, S; Tanida, J

2012-01-01

A multi-functional compound-eye endoscope enabling variable field-of-view and polarization imaging as well as extremely deep focus is presented, which is based on a compact compound-eye camera called TOMBO (thin observation module by bound optics). Fixed and movable mirrors are introduced to control the field of view. Metal-wire-grid polarizer thin film applicable to both of visible and near-infrared lights is attached to the lenses in TOMBO and light sources. Control of the field-of-view, polarization and wavelength of the illumination realizes several observation modes such as three-dimensional shape measurement, wide field-of-view, and close-up observation of the superficial tissues and structures beneath the skin.

Lightweight, Flexible, Thin, Integrated Solar-Power Packs

NASA Technical Reports Server (NTRS)

Hanson, Robert R.

2004-01-01

Lightweight, flexible, thin, one-piece, solar-power packs are undergoing development. Each power pack of this type is a complete, modular, integrated power-supply system comprising three power subsystems that, in conventional practice, have been constructed as separate units and connected to each other by wires. These power packs are amenable to a variety of uses: For example, they could be laminated to the tops of tents and other shelters to provide or augment power for portable electronic equipment in the field, and they could be used as power sources for such small portable electronic systems as radio transceivers (including data relays and cellular telephones), laptop computers, video camcorders, and Global Positioning System receivers.

Thin and long silver nanowires self-assembled in ionic liquids as a soft template: electrical and optical properties

PubMed Central

2014-01-01

Thin and long silver nanowires were successfully synthesized using the polyvinylpyrrolidone (PVP)-assisted polyol method in the presence of ionic liquids, tetrapropylammonium chloride and tetrapropylammonium bromide, which served as soft template salts. The first step involved the formation of Ag nanoparticles with a diameter of 40 to 50 nm through the reduction of silver nitrate. At the growing stage, the Ag nanoparticles were converted into thin and long one-dimensional wires, with uniform diameters of 30 ± 3 nm and lengths of up to 50 μm. These Ag nanowires showed an electrical conductivity of 0.3 × 105 S/cm, while the sheet resistance of a two-dimensional percolating Ag nanowire network exhibited a value of 20 Ω/sq with an optical transmittance of 93% and a low haze value. PMID:25024690

Thin and long silver nanowires self-assembled in ionic liquids as a soft template: electrical and optical properties.

PubMed

Chang, Min-Hwa; Cho, Hyun-Ah; Kim, Youn-Soo; Lee, Eun-Jong; Kim, Jin-Yeol

2014-01-01

Thin and long silver nanowires were successfully synthesized using the polyvinylpyrrolidone (PVP)-assisted polyol method in the presence of ionic liquids, tetrapropylammonium chloride and tetrapropylammonium bromide, which served as soft template salts. The first step involved the formation of Ag nanoparticles with a diameter of 40 to 50 nm through the reduction of silver nitrate. At the growing stage, the Ag nanoparticles were converted into thin and long one-dimensional wires, with uniform diameters of 30 ± 3 nm and lengths of up to 50 μm. These Ag nanowires showed an electrical conductivity of 0.3 × 10(5) S/cm, while the sheet resistance of a two-dimensional percolating Ag nanowire network exhibited a value of 20 Ω/sq with an optical transmittance of 93% and a low haze value.

Thin film strain gage development program

NASA Technical Reports Server (NTRS)

Grant, H. P.; Przybyszewski, J. S.; Anderson, W. L.; Claing, R. G.

1983-01-01

Sputtered thin-film dynamic strain gages of 2 millimeter (0.08 in) gage length and 10 micrometer (0.0004 in) thickness were fabricated on turbojet engine blades and tested in a simulated compressor environment. Four designs were developed, two for service to 600 K (600 F) and two for service to 900 K (1200 F). The program included a detailed study of guidelines for formulating strain-gage alloys to achieve superior dynamic and static gage performance. The tests included gage factor, fatigue, temperature cycling, spin to 100,000 G, and erosion. Since the installations are 30 times thinner than conventional wire strain gage installations, and any alteration of the aerodynamic, thermal, or structural performance of the blade is correspondingly reduced, dynamic strain measurement accuracy higher than that attained with conventional gages is expected. The low profile and good adherence of the thin film elements is expected to result in improved durability over conventional gage elements in engine tests.

NASA Tech Briefs, January 2003

NASA Technical Reports Server (NTRS)

2003-01-01

Topics covered include: Optoelectronic Tool Adds Scale Marks to Photographic Images; Compact Interconnection Networks Based on Quantum Dots; Laterally Coupled Quantum-Dot Distributed-Feedback Lasers; Bit-Serial Adder Based on Quantum Dots; Stabilized Fiber-Optic Distribution of Reference Frequency; Delay/Doppler-Mapping GPS-Reflection Remote-Sensing System; Ladar System Identifies Obstacles Partly Hidden by Grass; Survivable Failure Data Recorders for Spacecraft; Fiber-Optic Ammonia Sensors; Silicon Membrane Mirrors with Electrostatic Shape Actuators; Nanoscale Hot-Wire Probes for Boundary-Layer Flows; Theodolite with CCD Camera for Safe Measurement of Laser-Beam Pointing; Efficient Coupling of Lasers to Telescopes with Obscuration; Aligning Three Off-Axis Mirrors with Help of a DOE; Calibrating Laser Gas Measurements by Use of Natural CO2; Laser Ranging Simulation Program; Micro-Ball-Lens Optical Switch Driven by SMA Actuator; Evaluation of Charge Storage and Decay in Spacecraft Insulators; Alkaline Capacitors Based on Nitride Nanoparticles; Low-EC-Content Electrolytes for Low-Temperature Li-Ion Cells; Software for a GPS-Reflection Remote-Sensing System; Software for Building Models of 3D Objects via the Internet; "Virtual Cockpit Window" for a Windowless Aerospacecraft; CLARAty Functional-Layer Software; Java Library for Input and Output of Image Data and Metadata; Software for Estimating Costs of Testing Rocket Engines; Energy-Absorbing, Lightweight Wheels; Viscoelastic Vibration Dampers for Turbomachine Blades; Soft Landing of Spacecraft on Energy-Absorbing Self-Deployable Cushions; Pneumatically Actuated Miniature Peristaltic Vacuum Pumps; Miniature Gas-Turbine Power Generator; Pressure-Sensor Assembly Technique; Wafer-Level Membrane-Transfer Process for Fabricating MEMS; A Reactive-Ion Etch for Patterning Piezoelectric Thin Film; Wavelet-Based Real-Time Diagnosis of Complex Systems; Quantum Search in Hilbert Space; Analytic Method for Computing Instrument Pointing Jitter; and Semiselective Optoelectronic Sensors for Monitoring Microbes.

Promising Results from Three NASA SBIR Solar Array Technology Development Programs

NASA Technical Reports Server (NTRS)

Eskenazi, Mike; White, Steve; Spence, Brian; Douglas, Mark; Glick, Mike; Pavlick, Ariel; Murphy, David; O'Neill, Mark; McDanal, A. J.; Piszczor, Michael

2005-01-01

Results from three NASA SBIR solar array technology programs are presented. The programs discussed are: 1) Thin Film Photovoltaic UltraFlex Solar Array; 2) Low Cost/Mass Electrostatically Clean Solar Array (ESCA); and 3) Stretched Lens Array SquareRigger (SLASR). The purpose of the Thin Film UltraFlex (TFUF) Program is to mature and validate the use of advanced flexible thin film photovoltaics blankets as the electrical subsystem element within an UltraFlex solar array structural system. In this program operational prototype flexible array segments, using United Solar amorphous silicon cells, are being manufactured and tested for the flight qualified UltraFlex structure. In addition, large size (e.g. 10 kW GEO) TFUF wing systems are being designed and analyzed. Thermal cycle and electrical test and analysis results from the TFUF program are presented. The purpose of the second program entitled, Low Cost/Mass Electrostatically Clean Solar Array (ESCA) System, is to develop an Electrostatically Clean Solar Array meeting NASA s design requirements and ready this technology for commercialization and use on the NASA MMS and GED missions. The ESCA designs developed use flight proven materials and processes to create a ESCA system that yields low cost, low mass, high reliability, high power density, and is adaptable to any cell type and coverglass thickness. All program objectives, which included developing specifications, creating ESCA concepts, concept analysis and trade studies, producing detailed designs of the most promising ESCA treatments, manufacturing ESCA demonstration panels, and LEO (2,000 cycles) and GEO (1,350 cycles) thermal cycling testing of the down-selected designs were successfully achieved. The purpose of the third program entitled, "High Power Platform for the Stretched Lens Array," is to develop an extremely lightweight, high efficiency, high power, high voltage, and low stowed volume solar array suitable for very high power (multi-kW to MW) applications. These objectives are achieved by combining two cutting edge technologies, the SquareRigger solar array structure and the Stretched Lens Array (SLA). The SLA SquareRigger solar array is termed SLASR. All program objectives, which included developing specifications, creating preliminary designs for a near-term SLASR, detailed structural, mass, power, and sizing analyses, fabrication and power testing of a functional flight-like SLASR solar blanket, were successfully achieved.

Adhesion of liposomes: a quartz crystal microbalance study

NASA Astrophysics Data System (ADS)

Lüthgens, Eike; Herrig, Alexander; Kastl, Katja; Steinem, Claudia; Reiss, Björn; Wegener, Joachim; Pignataro, Bruno; Janshoff, Andreas

2003-11-01

Three different systems are presented, exploring the adhesion of liposomes mediated by electrostatic and lipid-protein interactions as well as molecular recognition of ligand receptor pairs. Liposomes are frequently used to gain insight into the complicated processes involving adhesion and subsequent events such as fusion and fission mainly triggered by specific proteins. We combined liposome technology with the quartz crystal microbalance (QCM) technique as a powerful tool to study the hidden interface between the membrane and functionalized surface. Electrostatic attraction and molecular recognition were employed to bind liposomes to the functionalized quartz crystal. The QCM was used to distinguish between adsorption of vesicles and rupture due to strong adhesive forces. Intact vesicles display viscoelastic behaviour, while planar lipid bilayers as a result of vesicle rupture can be modelled by a thin rigid film. Furthermore, the adhesion of cells was modelled successfully by receptor bearing liposomes. Scanning force microscopy was used to confirm the results obtained by QCM measurements.

Electronic reconstruction of doped Mott insulator heterojunctions

NASA Astrophysics Data System (ADS)

Charlebois, M.; Hassan, S. R.; Karan, R.; Dion, M.; Senechal, D.; Tremblay, A.-M. S.

2012-02-01

Correlated electron heterostructures became a possible alternative when thin-film deposition techniques achieved structures with a sharp interface transition [1]. Soon thereafter, Okamoto & Millis introduced the concept of ``electronic reconstruction'' [2]. We study here the electronic reconstruction of doped Mott insulator heterostructures based on a Cluster Dynamical Mean Field Theory (CDMFT) calculations of the Hubbard model in the limit where electrostatic energy dominates over the kinetic energy associated with transport across layers. The grand potential of individual layers is first computed within CDMFT and then the electrostatic potential energy is taken into account in the Hartree approximation. The charge reconstruction in an ensemble of stacked planes of different nature can lead to a distribution of electron charge and to transport properties that are unique to doped-Mott insulators.[4pt] [1] J. Mannhart, D. G. Schlom, Science 327, 1607 (2010).[0pt] [2] S. Okamoto and A. J. Millis, Nature 428, 630 (2004).

Electrostatic interactions among hydrophobic ions in lipid bilayer membranes.

PubMed Central

Andersen, O S; Feldberg, S; Nakadomari, H; Levy, S; McLaughlin, S

1978-01-01

We have shown that the absorption of tetraphenylborate into black lipid membranes formed from either bacterial phosphatidylethanolamine or glycerolmonooleate produces concentration-dependent changes in the electrostatic potential between the membrane interior and the bulk aqueous phases. These potential changes were studied by a variety of techniques: voltage clamp, charge pulse, and "probe" measurements on black lipid membranes; electrophroetic mobility measurements on phospholipid vesicles; and surface potential measurements on phospholipid monolayers. The magnitude of the potential changes indicates that tetraphenylborate absorbs into a region of the membrane with a low dielectric constant, where it produces substantial boundary potentials, as first suggested by Markin et al. (1971). Many features of our data can be explained by a simple three-capacitor model, which we develop in a self-consistent manner. Some discrepancies between our data and the simple model suggest that discrete charge phenomena may be important within these thin membranes. PMID:620077

Customized Hermetic Feedthrough Developed to Isolate Fluids

NASA Technical Reports Server (NTRS)

Meredith, Roger D.

1999-01-01

A common problem occurs when refrigerant fluids wick inside the insulation of thermocouple wires through a compressor's casing feedthrough and then leak into the adjacent disconnect box outside the casing. Leaking fluids create an unfavorable situation inside the disconnect box and may contaminate the fluids. To address this problem, NASA Lewis Research Center s Manufacturing Engineering Division developed a customized hermetic feedthrough for a bank of Worthington compressors. In these compressors, bearing temperatures are measured by internal thermocouples embedded in bearings located inside the compressor casings. The thermocouple wires need to be routed outside the casing and read at another location. These wires are short and are terminated to a disconnect strip inside the casing. The bearings operate at about 170 F, but because the casing is filled with R12 refrigerant oil, the casing has a maximum temperature of about 100 F. The operating conditions of these compressors permit the use of an epoxy that is compatible with the R12 fluid. The desired finished product is a stainless steel tube that has been filled solid with epoxy after thermocouple wires bonded and sealed by epoxy have been inserted through its length. Shrink tubing extends from both ends of the tube. The process that was developed to isolate the thermocouple wires from the R12 fluid follows. For this application, use an 8-in.-long piece of 0.500-in. 304 stainless steel tube with six pairs of 24-gauge stranded, PTFE-insulated (polytetrafluoroethylene) type "T" thermocouple wires for each feedthrough. Use shrink tubing to strain relief the insulated wires at their exit from the stainless steel tube. Cut the wire to length and identify the location of the stainless steel tube sleeve with masking tape. Then, remove the outer insulation from a 2-in. section of wire that will be inside the tube, and carefully strip to bare wire a 1-in. section in the middle of the section with the outer insulation removed. For an effective seal, the epoxy must penetrate between the strands when stranded conductors are used. Make the seal with epoxy bond on the bare wire. The bare wire must be encapsulated with a thin layer of the epoxy that leaves only a very low profile. These encapsulated wires must cure before the assembly can be continued. Then, inspect the cured wires for complete encapsulation before going to the next step. Insert the wires in the stainless steel tube and orient them so that the epoxied stripped sections are staggered within the tube; then, apply shrink tubing to one end of the cleaned wires, positioning it inside the edge of the tube. The small gaps between the wires on the other end will be used to inject the epoxy into the tube. Let the epoxy cure inside the tube, free of any voids. Then, continue to fill the tube until the entire 8-in. length is nearly filled, allowing room for the other strain-relieving shrink tubing. Since this first design, the process has been adjusted to fit many needs and situations. Customized feedthroughs have been assembled from various wire types, wire gauges, and/or stainless steel tube passages. The fittings selected to mount these feedthroughs allow their use in other areas, such as pressure or vacuum systems.

Periodic unsteady effects on turbulent boundary layer transport and heat transfer: An experimental investigation in a cylinder-wall junction flow

NASA Astrophysics Data System (ADS)

Xie, Qi

Heat transfer in a turbulent boundary layer downstream of junction with a cylinder has many engineering applications including controlling heat transfer to the endwall in gas turbine passages and cooling of protruding electronic chips. The main objective of this research is to study the fundamental process of heat transport and wall heat transfer in a turbulent three-dimensional flow superimposed with local large-scale periodic unsteadiness generated by vortex shedding from the cylinder. Direct measurements of the Reynolds heat fluxes (/line{utheta},\\ /line{vtheta}\\ and\\ /line{wtheta}) and time-resolved wall heat transfer rate will provide insight into unsteady flow behavior and data for advanced turbulence models for numerical simulation of complex engineering flows. Experiments were conducted in an open-circuit, low-speed wind tunnel. Reynolds stresses and heat fluxes were obtained from turbulent heat-flux probes which consisted of two hot wires, arranged in an X-wire configuration, and a cold wire located in front of the X-wire. Thin-film surface heat flux sensors were designed for measuring time-resolved wall heat flux. A reference probe and conditional-sampling technique connected the flow field dynamics to wall heat transfer. An event detecting and ensemble-averaging method was developed to separate effects of unsteadiness from those of background turbulence. Results indicate that unsteadiness affects both heat transport and wall heat transfer. The flow behind the cylinder can be characterized by three regions: (1) Wake region, where unsteadiness is observed to have modest effect; (2) Unsteady region, where the strongest unsteadiness effect is found; (3) Outer region, where the flow approaches the two-dimensional boundary-layer behavior. Vortex shedding from both sides of the cylinder contributes to mixing enhancement in the wake region. Unsteadiness contributes up to 51% of vertical and 59% of spanwise turbulent heat fluxes in the unsteady region. The instantaneous wall Stanton number increased up to 100% compared with an undisturbed flow. Large-scale fluctuations of wall Stanton number were due to the periodic thinning and thickening of the thermal layer caused by periodic vertical velocity fluctuations. This suggests that the outerlayer motion affects near-wall flow behavior and wall heat transfer.

Thin-Wire Modeling Techniques Applied to Antenna Analysis.

DTIC Science & Technology

1974-10-11

Ol- MULT11 CRN LOOP ANTENNA ... 30 2.4.1 Balanced vs unbalanced operation ... 3 1 2.4.2 Horizontal vs vertical configuration ... 33 3.0...of the Ml A-l Mimloop ... 28 Hl; multiturn loop antenna of Ohio State University ...31 Configurations ot balanced and unbalanced MTLs ... 32...4. Evaluation of Multiturn Loop Antenna In each example the specific project is outlined and the antenna analysis problems of particular interest

Developing NanoFoil-Heated Thin-Film Thermal Battery

DTIC Science & Technology

2013-09-01

buffer discs (in gray) sandwiching the NanoFoil disc (in yellow). Two Microtherm discs (in dark gray) bracketed the sandwich to prevent excessive heat...of the fuse strip with a Microtherm disc. Cathode Electrolyte Anode Microtherm Heat paper NanoFoil Buffer Agilent 34970A 606.5 Nichrome wire Maccor...gray) sandwiching the NanoFoil disc (in yellow). Two Microtherm discs (in dark gray) bracketed the sandwich to prevent excessive heat loss

Wavelength specific excitation of gold nanoparticle thin-films

NASA Astrophysics Data System (ADS)

Lucas, Thomas M.; James, Kurtis T.; Beharic, Jasmin; Moiseeva, Evgeniya V.; Keynton, Robert S.; O'Toole, Martin G.; Harnett, Cindy K.

2014-01-01

Advances in microelectromechanical systems (MEMS) continue to empower researchers with the ability to sense and actuate at the micro scale. Thermally driven MEMS components are often used for their rapid response and ability to apply relatively high forces. However, thermally driven MEMS often have high power consumption and require physical wiring to the device. This work demonstrates a basis for designing light-powered MEMS with a wavelength specific response. This is accomplished by patterning surface regions with a thin film containing gold nanoparticles that are tuned to have an absorption peak at a particular wavelength. The heating behavior of these patterned surfaces is selected by the wavelength of laser directed at the sample. This method also eliminates the need for wires to power a device. The results demonstrate that gold nanoparticle films are effective wavelength-selective absorbers. This "hybrid" of infrared absorbent gold nanoparticles and MEMS fabrication technology has potential applications in light-actuated switches and other mechanical structures that must bend at specific regions. Deposition methods and surface chemistry will be integrated with three-dimensional MEMS structures in the next phase of this work. The long-term goal of this project is a system of light-powered microactuators for exploring cellular responses to mechanical stimuli, increasing our fundamental understanding of tissue response to everyday mechanical stresses at the molecular level.

Deep Charging Evaluation of Satellite Power and Communication System Components

NASA Technical Reports Server (NTRS)

Schneider, T. A.; Vaughn, J. A.; Chu, B.; Wong, F.; Gardiner, G.; Wright, K. H.; Phillips, B.

2016-01-01

A set of deep charging tests has been carried out by NASA's Marshall Space Flight Center on subscale flight-like samples developed by Space Systems/Loral, LLC. The samples, which included solar array wire coupons, a photovoltaic cell coupon, and a coaxial microwave transmission cable, were placed in passive and active (powered) circuit configurations and exposed to electron radiation. The energy of the electron radiation was chosen to deeply penetrate insulating (dielectric) materials on each sample. Each circuit configuration was monitored to determine if potentially damaging electrostatic discharge events (arcs) were developed on the coupon as a result of deep charging. The motivation for the test, along with charging levels, experimental setup, sample details, and results will be discussed.

Vanadium Redox Flow Batteries Using meta-Polybenzimidazole-Based Membranes of Different Thicknesses.

PubMed

Noh, Chanho; Jung, Mina; Henkensmeier, Dirk; Nam, Suk Woo; Kwon, Yongchai

2017-10-25

15, 25, and 35 μm thick meta-polybenzimidazole (PBI) membranes are doped with H 2 SO 4 and tested in a vanadium redox flow battery (VRFB). Their performances are compared with those of Nafion membranes. Immersed in 2 M H 2 SO 4 , PBI absorbs about 2 mol of H 2 SO 4 per mole of repeat unit. This results in low conductivity and low voltage efficiency (VE). In ex-situ tests, meta-PBI shows a negligible crossover of V 3+ and V 4+ ions, much lower than that of Nafion. This is due to electrostatic repulsive forces between vanadium cations and positively charged protonated PBI backbones, and the molecular sieving effect of PBI's nanosized pores. It turns out that charge efficiency (CE) of VRFBs using meta-PBI-based membranes is unaffected by or slightly increases with decreasing membrane thickness. Thick meta-PBI membranes require about 100 mV larger potentials to achieve the same charging current as thin meta-PBI membranes. This additional potential may increase side reactions or enable more vanadium ions to overcome the electrostatic energy barrier and to enter the membrane. On this basis, H 2 SO 4 -doped meta-PBI membranes should be thin to achieve high VE and CE. The energy efficiency of 15 μm thick PBI reaches 92%, exceeding that of Nafion 212 and 117 (N212 and N117) at 40 mA cm -2 .

Electrostatic spray deposition of porous Fe 2O 3 thin films as anode material with improved electrochemical performance for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Wang, L.; Xu, H. W.; Chen, P. C.; Zhang, D. W.; Ding, C. X.; Chen, C. H.

Iron oxide materials are attractive anode materials for lithium-ion batteries for their high capacity and low cost compared with graphite and most of other transition metal oxides. Porous carbon-free α-Fe 2O 3 films with two types of pore size distribution were prepared by electrostatic spray deposition, and they were characterized by X-ray diffraction, scanning electron microscopy and X-ray absorption near-edge spectroscopy. The 200 °C-deposited thin film exhibits a high reversible capacity of up to 1080 mAh g -1, while the initial capacity loss is at a remarkable low level (19.8%). Besides, the energy efficiency and energy specific average potential (E av) of the Fe 2O 3 films during charge/discharge process were also investigated. The results indicate that the porous α-Fe 2O 3 films have significantly higher energy density than Li 4Ti 5O 12 while it has a similar E av of about 1.5 V. Due to the porous structure that can buffer the volume changes during lithium intercalation/de-intercalation, the films exhibit stable cycling performance. As a potential anode material for high performance lithium-ion batteries that can be applied on electric vehicle and energy storage, rate capability and electrochemical performance under high-low temperatures were also investigated.

Tailoring nanoscale morphology of polymer: Fullerene blends using electrostatic field

DOE PAGES

Elshobaki, Moneim; Gebhardt, Ryan; Carr, John; ...

2016-12-05

In this paper, to tailor the nanoscale phase separation in polymer/fullerene blends, we study the effect of electrostatic field (E-field) on the solidification of poly(3-hexylthiophene-2, 5-diyl) (P3HT):[6,6]-phenyl-C61-butyric acid methyl ester (PC 60BM) bulk heterojunction (BHJ). In addition to untreated sample (control); wet P3HT:PC 60BM thin films were exposed to E-field of Van de Graaff (VDG) generator at three different directions – horizontal (H), tilted (T) and vertical (V) – relative to the plane of the substrate. Surface and bulk characterizations of field-treated BHJs affirm that fullerene molecules can easily penetrate the spaghetti-like P3HT and move up and down following themore » E-field. E-field treatment yields thin films with large P3HT- and PCBM-rich domains acting as continuous pathways for efficient charge separation, transport, and collection. We improve; (1) the hole mobility values up to 19.4 × 10 -4 ± 1.6 × 10 -4 cm 2 V -1 s -1 (117% higher than the control), and (2) power conversion efficient (PCE) of conventional and inverted OPVs recording 2.58 ± 0.02% and 4.1 ± 0.4%. This E-field approach can serve as a new morphology-tuning technique, which is generally applicable to other polymer-fullerene systems.« less

Room-temperature growth of thin films of niobium on strontium titanate (0 0 1) single-crystal substrates for superconducting joints

NASA Astrophysics Data System (ADS)

Shimizu, Yuhei; Tonooka, Kazuhiko; Yoshida, Yoshiyuki; Furuse, Mitsuho; Takashima, Hiroshi

2018-06-01

With the eventual aim of forming joints between superconducting wires of YBa2Cu3O7-δ (YBCO), thin films of Nb were grown at room-temperature on SrTiO3 (STO) (0 0 1), a single-crystal substrate that shows good lattice matching with YBCO. The crystallinity, surface morphology, and superconducting properties of the Nb thin films were investigated and compared with those of similar films grown on a silica glass substrate. The Nb thin films grew with an (hh0) orientation on both substrates. The crystallinity of the Nb thin films on the STO substrate was higher than that on the silica glass substrate. X-ray diffraction measurements and observation of the surface morphology by atomic-force microscopy indicated that Nb grew in the plane along the [1 0 0] and [0 1 0] directions of the STO substrate. This growth mode relaxes strain between Nb and STO, and is believed to lead to the high crystallinity observed. As a result, the Nb thin films on the STO substrates showed lower electric resistivity and a higher superconducting transition temperature than did those on the silica glass substrates. The results of this study should be useful in relation to the production of superconducting joints.

Self assembled sulfur induced interconnected nanostructure TiO2 electrode for visible light photoresponse and photocatalytic application

NASA Astrophysics Data System (ADS)

Anitha, B.; Ravidhas, C.; Venkatesh, R.; Raj, A. Moses Ezhil; Ravichandran, K.; Subramanian, B.; Sanjeeviraja, C.

2017-07-01

Pristine TiO2 and sulfur doped TiO2 (S-TiO2) thin films were coated over the glass substrates by varying the concentration of sulfur source (thiourea - 2, 4, 6, 8 and 10 at%) using a cost-effective Jet nebulizer spray technique. The deposited thin films were in anatase phase with the tetragonal structure analyzed from the XRD pattern. The chemical state of the elements was determined from XPS analysis. Pristine TiO2 and S-TiO2 thin films depict the presence of spherical particles embedded over 3-D interconnected wire-like structure from SEM analysis. Optical studies revealed reduction in band gap of S-TiO2 films on increasing the sulfur concentration (3.2-2.8 eV). The sulfur incorporation in TiO2 lattice confirmed by the fall in intensity of near band edge emission as observed from room temperature PL spectra. The charge carrier dynamics of the prepared thin films were studied by means of steady state and transient photoconduction measurements. The photocatalytic performance of pristine TiO2 and S-TiO2 thin films for the degradation of malachite green dye was investigated under visible light.

Novel Organic Membrane-based Thin-film Microsensors for the Determination of Heavy Metal Cations

PubMed Central

Arida, Hassan A.; Kloock, Joachim P.; Schöning, Michael J.

2006-01-01

A first step towards the fabrication and electrochemical evaluation of thin-film microsensors based on organic PVC membranes for the determination of Hg(II), Cd(II), Pb(II) and Cu(II) ions in solutions has been realised. The membrane-coating mixture used in the preparation of this new type of microsensors is incorporating PVC as supporting matrix, o-nitrophenyloctylether (o-NPOE) as solvent mediator and a recently synthesized Hg[dimethylglyoxime(phene)]2+ and Bis-(4-hydroxyacetophenone)-ethylenediamine as electroactive materials for Hg(II) and Cd(II), respectively. A set of three commercialised ionophores for Cd(II), Pb(II) and Cu(II) has been also used for comparison. Thin-film microsensors based on these membranes showed a Nernstian response of slope (26-30 mV/dec.) for the respective tested cations. The potentiometric response characteristics (linear range, pH range, detection limit and response time) are comparable with those obtained by conventional membranes as well as coated wire electrodes prepared from the same membrane. The realisation of the new organic membrane-based thin-film microsensors overcomes the problem of an insufficient selectivity of solid-state-based thin-film sensors.

Fabrication of high-quality single-crystal Cu thin films using radio-frequency sputtering.

PubMed

Lee, Seunghun; Kim, Ji Young; Lee, Tae-Woo; Kim, Won-Kyung; Kim, Bum-Su; Park, Ji Hun; Bae, Jong-Seong; Cho, Yong Chan; Kim, Jungdae; Oh, Min-Wook; Hwang, Cheol Seong; Jeong, Se-Young

2014-08-29

Copper (Cu) thin films have been widely used as electrodes and interconnection wires in integrated electronic circuits, and more recently as substrates for the synthesis of graphene. However, the ultra-high vacuum processes required for high-quality Cu film fabrication, such as molecular beam epitaxy (MBE), restricts mass production with low cost. In this work, we demonstrated high-quality Cu thin films using a single-crystal Cu target and radio-frequency (RF) sputtering technique; the resulting film quality was comparable to that produced using MBE, even under unfavorable conditions for pure Cu film growth. The Cu thin film was epitaxially grown on an Al2O3 (sapphire) (0001) substrate, and had high crystalline orientation along the (111) direction. Despite the 10(-3) Pa vacuum conditions, the resulting thin film was oxygen free due to the high chemical stability of the sputtered specimen from a single-crystal target; moreover, the deposited film had >5× higher adhesion force than that produced using a polycrystalline target. This fabrication method enabled Cu films to be obtained using a simple, manufacturing-friendly process on a large-area substrate, making our findings relevant for industrial applications.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zestos, Alexander G.; Yang, Cheng; Jacobs, Christopher B.

Carbon nanomaterials are advantageous as electrodes for neurotransmitter detection, but the difficulty of nanomaterials deposition on electrode substrates limits the reproducibility and future applications. In our study, we used plasma enhanced chemical vapor deposition (PECVD) to directly grow a thin layer of carbon nanospikes (CNS) on cylindrical metal substrates. No catalyst is required and the CNS surface coverage is uniform over the cylindrical metal substrate. We characterized the CNS growth on several metallic substrates including tantalum, niobium, palladium, and nickel wires. Using fast-scan cyclic voltammetry (FSCV), bare metal wires could not detect 1 mu M dopamine while carbon nanospike coatedmore » wires could. Moreover, the highest sensitivity and optimized S/N ratio was recorded from carbon nanospike-tantalum (CNS-Ta) microwires grown for 7.5 minutes, which had a LOD of 8 +/- 2 nM for dopamine with FSCV. CNS-Ta microelectrodes were more reversible and had a smaller Delta E-p for dopamine than carbon-fiber microelectrodes, suggesting faster electron transfer kinetics. The kinetics of dopamine redox were adsorption controlled at CNS-Ta microelectrodes and repeated electrochemical measurements displayed stability for up to ten hours in vitro and over a ten day period as well. The oxidation potential was significantly different for ascorbic acid and uric acid compared to dopamine. Finally, growing carbon nanospikes on metal wires is a promising method to produce uniformly-coated, carbon nanostructured cylindrical microelectrodes for sensitive dopamine detection.« less

Placement of trans-sternal wires according to an ellipsoid pressure vessel model of sternal forces.

PubMed

Casha, Aaron R; Manché, Alex; Gauci, Marilyn; Camilleri-Podesta, Marie-Therese; Schembri-Wismayer, Pierre; Sant, Zdenka; Gatt, Ruben; Grima, Joseph N

2012-03-01

Dehiscence of median sternotomy wounds remains a clinical problem. Wall forces in thin-walled pressure vessels can be calculated by membrane stress theory. An ellipsoid pressure vessel model of sternal forces is presented together with its application for optimal wire placement in the sternum. Sternal forces were calculated by computational simulation using an ellipsoid chest wall model. Sternal forces were correlated with different sternal thicknesses and radio-density as measured by computerized tomography (CT) scans of the sternum. A comparison of alternative placement of trans-sternal wires located either at the levels of the costal cartilages or the intercostal spaces was made. The ellipsoid pressure vessel model shows that higher levels of stress are operative at increasing chest diameter (P < 0.001). CT scans show that the thickness of the sternal body is on average 3 mm and 30% thicker (P < 0.001) and 53% more radio-dense (P < 0.001) at the costal cartilage levels when compared with adjacent intercostal spaces. This results in a decrease of average sternal stress from 438 kPa at the intercostal space level to 338 kPa at the costal cartilage level (P = 0.003). Biomechanical modelling suggests that placement of trans-sternal wires at the thicker bone and more radio-dense level of the costal cartilages will result in reduced stress.

Origin of thickness dependence of structural phase transition temperatures in BiFeO 3 thin films

DOE PAGES

Yang, Yongsoo; Beekman, Christianne; Siemons, Wolter; ...

2016-03-28

In this study, two structural phase transitions are investigated in highly strained BiFeO 3 thin films grown on LaAlO 3 substrates, as a function of film thickness and temperature via synchrotron x-ray diffraction. Both transition temperatures (upon heating: monoclinic MC to monoclinic MA, and MA to tetragonal) decrease as the film becomes thinner. The existence of an interface layer at the film-substrate interface, deduced from half-order peak intensities, contributes to this behavior only for the thinnest samples; at larger thicknesses (above a few nanometers) the temperature dependence can be understood in terms of electrostatic considerations akin to size effects inmore » ferroelectric phase transitions, but observed here for structural phase transitions within the ferroelectric phase and related to the rearrangement rather than the formation of domains. For ultra-thin films, the tetragonal structure is stable at all investigated temperatures (down to 30 K).« less

PZT Thin Film Piezoelectric Traveling Wave Motor

NASA Technical Reports Server (NTRS)

Shen, Dexin; Zhang, Baoan; Yang, Genqing; Jiao, Jiwei; Lu, Jianguo; Wang, Weiyuan

1995-01-01

With the development of micro-electro-mechanical systems (MEMS), its various applications are attracting more and more attention. Among MEMS, micro motors, electrostatic and electromagnetic, are the typical and important ones. As an alternative approach, the piezoelectric traveling wave micro motor, based on thin film material and integrated circuit technologies, circumvents many of the drawbacks of the above mentioned two types of motors and displays distinct advantages. In this paper we report on a lead-zirconate-titanate (PZT) piezoelectric thin film traveling wave motor. The PZT film with a thickness of 150 micrometers and a diameter of 8 mm was first deposited onto a metal substrate as the stator material. Then, eight sections were patterned to form the stator electrodes. The rotor had an 8 kHz frequency power supply. The rotation speed of the motor is 100 rpm. The relationship of the friction between the stator and the rotor and the structure of the rotor on rotation were also studied.

Direct evidence for the spin cycloid in strained nanoscale bismuth ferrite thin films

PubMed Central

Bertinshaw, Joel; Maran, Ronald; Callori, Sara J.; Ramesh, Vidya; Cheung, Jeffery; Danilkin, Sergey A.; Lee, Wai Tung; Hu, Songbai; Seidel, Jan; Valanoor, Nagarajan; Ulrich, Clemens

2016-01-01

Magnonic devices that utilize electric control of spin waves mediated by complex spin textures are an emerging direction in spintronics research. Room-temperature multiferroic materials, such as bismuth ferrite (BiFeO3), would be ideal candidates for this purpose. To realize magnonic devices, a robust long-range spin cycloid with well-known direction is desired, since it is a prerequisite for the magnetoelectric coupling. Despite extensive investigation, the stabilization of a large-scale uniform spin cycloid in nanoscale (100 nm) thin BiFeO3 films has not been accomplished. Here, we demonstrate cycloidal spin order in 100 nm BiFeO3 thin films through the careful choice of crystallographic orientation, and control of the electrostatic and strain boundary conditions. Neutron diffraction, in conjunction with X-ray diffraction, reveals an incommensurate spin cycloid with a unique [11] propagation direction. While this direction is different from bulk BiFeO3, the cycloid length and Néel temperature remain equivalent to bulk at room temperature. PMID:27585637

Multiple Differential-Amplifier MMICs Embedded in Waveguides

NASA Technical Reports Server (NTRS)

Kangaslahti, Pekka; Schlecht, Erich

2010-01-01

Compact amplifier assemblies of a type now being developed for operation at frequencies of hundreds of gigahertz comprise multiple amplifier units in parallel arrangements to increase power and/or cascade arrangements to increase gains. Each amplifier unit is a monolithic microwave integrated circuit (MMIC) implementation of a pair of amplifiers in differential (in contradistinction to single-ended) configuration. Heretofore, in cascading amplifiers to increase gain, it has been common practice to interconnect the amplifiers by use of wires and/or thin films on substrates. This practice has not yielded satisfactory results at frequencies greater than 200 Hz, in each case, for either or both of two reasons: Wire bonds introduce large discontinuities. Because the interconnections are typically tens of wavelengths long, any impedance mismatches give rise to ripples in the gain-vs.-frequency response, which degrade the performance of the cascade.

Fabrication and Characterization of Miniaturized Thermocouples

NASA Astrophysics Data System (ADS)

Munzel, Marco; Peinke, Joachim; Kittel, Achim

2002-11-01

The measurement of thermal fluctuations is important for discovering transport features of a passive scalar in fluids. We present a thermal sensor based on a miniaturized thermocouple. Its coaxial setup results from the fabrication as a micropipette normally used in neurobiology. The glass micropipettes contain a core of gold, antimony, or resistance wire and are coated with platinum. The core material is inserted as molten metal or wire and thinned during the fabrication process. The achieved tip diameters are 1μm and less which enhance the spatial and temporal resolution significantly. Because of its chemically inert coating, these sensors are applicative for detecting temperature fluctuations in large variety of liquids and gases. In addition, such thermocouples are intrinsically suitable for applications in scanning probe microscopy. The characterization of these sensors and first results from turbulent free-jet measurements are presented.

The effect of Birkeland currents on magnetic field topology

NASA Technical Reports Server (NTRS)

Peroomian, Vahe; Lyons, Larry R.; Schulz, Michael

1996-01-01

A technique was developed for the inclusion of large scale magnetospheric current systems in magnetic field models. The region 1 and 2 Birkeland current systems are included in the source surface model of the terrestrial magnetosphere. The region 1 and 2 Birkeland currents are placed in the model using a series of field aligned, infinitely thin wire segments. The normal component of the magnetic field from these currents is calculated on the surface of the magnetopause and shielded using image current carrying wires placed outside of the magnetosphere. It is found that the inclusion of the Birkeland currents in the model results in a northward magnetic field in the near-midnight tail, leading to the closure of previously open flux in the tail, and a southward magnetic field in the flanks. A sunward shift in the separatrix is observed.

Engineering and experimental analyses of the tensile loads applied during strength testing of direct bonded orthodontic brackets.

PubMed

Katona, T R; Chen, J

1994-08-01

The stress levels within the cement layer (hence, the apparent strength) of a direct bonded orthodontic bracket depends, to a large extent, on the alignment of the tensile loads that are applied to the specimen. The purpose of this analysis was to determine how the construction of a ligature wire harness affects the alignment of the applied loads. Tensile tests conducted on a modified bracket/cement system showed large variations in the force-elongation curve profiles. An engineering model was developed to explain these deviations. The results indicate that it is virtually impossible to evenly apply tensile loads to the bracket. It was also proposed that long harnesses constructed with thin ligature wire, prestressing the harness, and lubrication may reduce some of the effects of unavoidable load-bracket misalignment.

Finite Element Analysis of Adaptive-Stiffening and Shape-Control SMA Hybrid Composites

NASA Technical Reports Server (NTRS)

Gao, Xiu-Jie; Turner, Travis L.; Burton, Deborah; Brinson, L. Catherine

2005-01-01

The usage of shape memory materials has extended rapidly to many fields, including medical devices, actuators, composites, structures and MEMS devices. For these various applications, shape memory alloys (SMAs) are available in various forms: bulk, wire, ribbon, thin film, and porous. In this work, the focus is on SMA hybrid composites with adaptive-stiffening or morphing functions. These composites are created by using SMA ribbons or wires embedded in a polymeric based composite panel/beam. Adaptive stiffening or morphing is activated via selective resistance heating or uniform thermal loads. To simulate the thermomechanical behavior of these composites, a SMA model was implemented using ABAQUS user element interface and finite element simulations of the systems were studied. Several examples are presented which show that the implemented model can be a very useful design and simulation tool for SMA hybrid composites.

Antenna theory: Analysis and design

NASA Astrophysics Data System (ADS)

Balanis, C. A.

The book's main objective is to introduce the fundamental principles of antenna theory and to apply them to the analysis, design, and measurements of antennas. In a description of antennas, the radiation mechanism is discussed along with the current distribution on a thin wire. Fundamental parameters of antennas are examined, taking into account the radiation pattern, radiation power density, radiation intensity, directivity, numerical techniques, gain, antenna efficiency, half-power beamwidth, beam efficiency, bandwidth, polarization, input impedance, and antenna temperature. Attention is given to radiation integrals and auxiliary potential functions, linear wire antennas, loop antennas, linear and circular arrays, self- and mutual impedances of linear elements and arrays, broadband dipoles and matching techniques, traveling wave and broadband antennas, frequency independent antennas and antenna miniaturization, the geometrical theory of diffraction, horns, reflectors and lens antennas, antenna synthesis and continuous sources, and antenna measurements.

Low-cost label-free electrical detection of artificial DNA nanostructures using solution-processed oxide thin-film transistors.

PubMed

Kim, Si Joon; Jung, Joohye; Lee, Keun Woo; Yoon, Doo Hyun; Jung, Tae Soo; Dugasani, Sreekantha Reddy; Park, Sung Ha; Kim, Hyun Jae

2013-11-13

A high-sensitivity, label-free method for detecting deoxyribonucleic acid (DNA) using solution-processed oxide thin-film transistors (TFTs) was developed. Double-crossover (DX) DNA nanostructures with different concentrations of divalent Cu ion (Cu(2+)) were immobilized on an In-Ga-Zn-O (IGZO) back-channel surface, which changed the electrical performance of the IGZO TFTs. The detection mechanism of the IGZO TFT-based DNA biosensor is attributed to electron trapping and electrostatic interactions caused by negatively charged phosphate groups on the DNA backbone. Furthermore, Cu(2+) in DX DNA nanostructures generates a current path when a gate bias is applied. The direct effect on the electrical response implies that solution-processed IGZO TFTs could be used to realize low-cost and high-sensitivity DNA biosensors.

Current Approach in Surface Plasmons for Thin Film and Wire Array Solar Cell Applications

PubMed Central

Zhou, Keya; Guo, Zhongyi; Liu, Shutian; Lee, Jung-Ho

2015-01-01

Surface plasmons, which exist along the interface of a metal and a dielectric, have been proposed as an efficient alternative method for light trapping in solar cells during the past ten years. With unique properties such as superior light scattering, optical trapping, guide mode coupling, near field concentration, and hot-electron generation, metallic nanoparticles or nanostructures can be tailored to a certain geometric design to enhance solar cell conversion efficiency and to reduce the material costs. In this article, we review current approaches on different kinds of solar cells, such as crystalline silicon (c-Si) and amorphous silicon (a-Si) thin film solar cells, organic solar cells, nanowire array solar cells, and single nanowire solar cells. PMID:28793457

Quality of Metal Deposited Flux Cored Wire With the System Fe-C-Si-Mn-Cr-Mo-Ni-V-Co

NASA Astrophysics Data System (ADS)

Gusev, Aleksander I.; Kozyrev, Nikolay A.; Osetkovskiy, Ivan V.; Kryukov, Roman E.; Kozyreva, Olga A.

2017-10-01

Studied the effect of the introduction of vanadium and cobalt into the charge powder fused wire system Fe-C-Si-Mn-Cr-Ni-Mo-V, used in cladding assemblies and equipment parts and mechanisms operating under abrasive and abrasive shock loads. the cored wires samples were manufactured in the laboratory conditions and using appropriate powder materials and as a carbonfluoride contained material were used the dust from gas purification of aluminum production, with the following components composition, %: Al2O3 = 21-46.23; F = 18-27; Na2O = 8-15; K2O = 0.4-6; CaO = 0.7-2.3; Si2O = 0.5-2.48; Fe2O3 = 2.1-3.27; C = 12.5-30.2; MnO = 0.07-0.9; MgO = 0.06-0.9; S = 0.09-0.19; P = 0.1-0.18. Surfacing was produced on the St3 metal plates in 6 layers under the AN-26C flux by welding truck ASAW-1250. Cutting and preparation of samples for research had been implemented. The chemical composition and the hydrogen content of the weld metal were determined by modern methods. The hardness and abrasion rate of weld metal had been measured. Conducted metallographic studies of weld metal: estimated microstructure, grain size, contamination of oxide non-metallic inclusions. Metallographic studies showed that the microstructure of the surfaced layer by cored wire system Fe-C-Si-Mn-Cr-Mo-Ni-V-Co is uniform, thin dendrite branches are observed. The microstructure consists of martensite, which is formed inside the borders of the former austenite grain retained austenite present in small amounts in the form of separate islands, and thin layers of δ-ferrite, which is located on the borders of the former austenite grains. Carried out an assessment the effect of the chemical composition of the deposited metal on the hardness and wear and hydrogen content. In consequence of multivariate correlation analysis, it was determined dependence to the hardness of the deposited layer and the wear resistance of the mass fraction of the elements included in the flux-cored wires of the system Fe-C-Si-Mn-Cr-Mo-Ni-V-Co. The calculated value of the average approximation error suggests that the dependence is adequate and can be used to determine the resulting indicators. These dependencies can be used to predict the hardness of the deposited layer and its wear resistance while changing the chemical composition of the weld metal.

Proceedings of the ECOM Hybrid Microcircuit Symposium, 1976

DTIC Science & Technology

1976-06-01

remove both stationary and moving clutter. The hex fast line receiver micrýocircuit is a thin film chip-and-wire microcircuit (shown in Figure 7) which...of the following: (a) multiple usage, (b) high volume production, or (c) moderate volume and multiple usage. These criteria are not hard and fast ...compounding when the circuit complexity increases. O particular concern are open or intermittent bonds, susceptibility to moisture and impurities in the

Innovation in Building Design

NASA Technical Reports Server (NTRS)

1983-01-01

Thomas & Betts Corporation's Flat Conductor Cables, or FCC, were developed of necessity as aircraft and spacecraft became increasingly complex. In order to reduce size and weight of components, the use of thin flat wire instead of relatively thick and protrusive round cable, provided a dramatic reduction of the space occupied by the many miles of power distribution lines in an aerospace vehicle. Commercially, FCC offers cost savings in simplified building construction, reduced installation time and ease of alteration.

Characterization of Metallic Coatings and Thin Films Produced by Railgun Deposition

DTIC Science & Technology

1988-01-01

homopolar generators (10), and compensating alternators (11) are capable of delivering mnegajoules of energy in less than a second. This advancement...a DC motor which consists of two rigid parallel conducting electrodes (rails) and a combined movable armature placed between them (7), Figure 2. The...discharge bank or homopolar generater, and the plasma device to another. The second study then ended with a group of experiments using an exploding wire

Drop Tower Characterization of Army Research Lab (ARL)-Fabricated Thin-Film Lead Zirconate Titanate (PZT) Transducers

DTIC Science & Technology

2012-04-01

TRADE NAME, TRADEMARK, MANUFACTURER , OR OTHERWISE, DOES NOT CONSTITUTE OR IMPLY ITS ENDORSEMENT, RECOMMENDATION, OR FAVORING BY THE U.S. GOVERNMENT...TRADE NAMES USE OF TRADE NAMES OR MANUFACTURERS IN THIS REPORT DOES NOT CONSTITUTE AN OFFICIAL ENDORSEMENT OR APPROVAL OF THE USE OF...on Gel-Pak Ready for Noodle Wire Attachment ..................... 10 13. Waveshaper (on Right) Beside a 0.5-Inch Steel Ball

Establishment of Production Cleanliness Criteria and Processes for Printed Wiring Boards and Assemblies.

DTIC Science & Technology

1981-12-01

H (hydrogen) and He (helium) are excluded since they have no outer shell electrons to eject. If the thin film analysis capability of Auger is...comtaminant profiling (C/P) system instrumentation will detect and intepret the amounts of contaminant species in an extract in terms of parts-per-billion...Nadas, and P. Fennell Evans, J. Phys. Chem;, 74 (1970), 4572. 215 4’. FILMED 7 4-85 DTIC

Heat-Flux Sensor For Hot Engine Cylinders

NASA Technical Reports Server (NTRS)

Kim, Walter S.; Barrows, Richard F.; Smith, Floyd A.; Koch, John

1989-01-01

Heat-flux sensor includes buried wire thermocouple and thin-film surface thermocouple, made of platinum and platinum with 13 percent rhodium. Sensor intended for use in ceramic-insulated, low-heat-rejection diesel engine at temperatures of about 1,000 K. Thermocouple junction resists environment in cylinder of advanced high-temperature diesel engine created by depositing overlapping films of Pt and 0.87 Pt/0.13 Rh on iron plug. Plug also contains internal thermocouple.

Advances in Sensors and Their Integration into Aircraft Guidance and Control Systems,

DTIC Science & Technology

1983-06-01

this function taking account of the limitations of the existing air- craft systems such as:- (a) Cockpit space (b) use of existing controls particularly...electrostatically focused under the influence of high potentials to form an electron image on a thin silicon wafer target upon which a very tightly spaced ...matrix of p-n junctions have been formed. The spacing of the diodes is of the order of n m. A gain mechanism is caused because the photo electrons

Multiscale Mass-Spring Models of Carbon Nanotube Foams

DTIC Science & Technology

2010-09-06

Mesarovic et al., 2007). The study of thin structural foams (Gibson and Ashby, 1998) for cushioning (Zhang et al., 2009), energy dissipation ( Teo et al...compressible foam-like behavior under compressive cycling loads (Suhr et al., 2007; Teo et al., 2007; Tao et al., 2008; Deck et al., 2007; Cao et al., 2005). 2...and electrostatic interaction be- tween individual and bundles of carbon nanotubes (Suhr et al., 2007; Teo et al., 2007; Tao et al., 2008; Deck et al

Avoidance of an electric field by insects: Fundamental biological phenomenon for an electrostatic pest-exclusion strategy

NASA Astrophysics Data System (ADS)

Matsuda, Y.; Nonomura, T.; Kakutani, K.; Kimbara, J.; Osamura, K.; Kusakari, S.; Toyoda, H.

2015-10-01

An electric field screen is a physical device used to exclude pest insects from greenhouses and warehouses to protect crop production and storage. The screen consists of iron insulated conductor wires (ICWs) arrayed in parallel and linked to each other, an electrostatic DC voltage generator used to supply a negative charge to the ICWs, and an earthed stainless net placed on one side of the ICW layer. The ICW was negatively charged to polarize the earthed net to create a positive charge on the ICW side surface, and an electric field formed between the opposite charges of the ICW and earthed net. The current study focused on the ability of the screen to repel insects reaching the screen net. This repulsion was a result of the insect's behaviour, i.e., the insects were deterred from entering the electric field of the screen. In fact, when the screen was negatively charged with the appropriate voltages, the insects placed their antennae inside the screen and then flew away without entering. Obviously, the insects recognized the electric field using their antennae and thereby avoided entering. Using a wide range of insects and spiders belonging to different taxonomic groups, we confirmed that the avoidance response to the electric field was common in these animals.