High sensitive space electric field sensing based on micro fiber interferometer with field force driven gold nanofilm.

PubMed

Zhu, Tao; Zhou, Liming; Liu, Min; Zhang, Jingdong; Shi, Leilei

2015-10-28

The traditional electrical field sensing can be realized by utilizing electro-optic materials or liquid crystals, and has limitations of easy breakdown, free assembly and difficult measurement of low-frequency. Here, we propose a new method to realize safe measurement of spatial dynamic electric field by using a micro fiber interferometer integrated with gold nanofilm. The energy of the electric charge received through antenna forms the intrinsic electric field with two micro electrodes, one of which is the 120 nm gold film vibration beam micromachined by femtosecond lasers and integrated with the micro fiber. The change of the intrinsic electric field force due to the spatial electric field will cause the vibration of the film beam. By demodulating the output signal of the micro fiber interferometer, the electric field can be measured. We demonstrate the detectable frequency ranges from tens of Hz to tens of KHz, and the minimum electric field intensity is ~200 V/m at 1 KHz. Our electric field measurement technology combining optical fiber interference with gold nanostructures shows the advantages of security, high sensitivity, compact size, and multiplexed multi-point and remote detection.

High sensitive space electric field sensing based on micro fiber interferometer with field force driven gold nanofilm

PubMed Central

Zhu, Tao; Zhou, Liming; Liu, Min; Zhang, Jingdong; Shi, Leilei

2015-01-01

The traditional electrical field sensing can be realized by utilizing electro-optic materials or liquid crystals, and has limitations of easy breakdown, free assembly and difficult measurement of low-frequency. Here, we propose a new method to realize safe measurement of spatial dynamic electric field by using a micro fiber interferometer integrated with gold nanofilm. The energy of the electric charge received through antenna forms the intrinsic electric field with two micro electrodes, one of which is the 120 nm gold film vibration beam micromachined by femtosecond lasers and integrated with the micro fiber. The change of the intrinsic electric field force due to the spatial electric field will cause the vibration of the film beam. By demodulating the output signal of the micro fiber interferometer, the electric field can be measured. We demonstrate the detectable frequency ranges from tens of Hz to tens of KHz, and the minimum electric field intensity is ~200 V/m at 1 KHz. Our electric field measurement technology combining optical fiber interference with gold nanostructures shows the advantages of security, high sensitivity, compact size, and multiplexed multi-point and remote detection. PMID:26507680

Field-aligned currents and the auroral electrojet

NASA Technical Reports Server (NTRS)

Cahill, L. J.; Potter, W. E.; Kintner, P. M.; Arnoldy, R. L.; Choy, L. W.

1974-01-01

A Nike Tomahawk with fields and particles payload was launched on Nov. 18, 1970, over a strong westward electrojet current and auroral forms moving rapidly to the east. Electron fluxes moving up and down the magnetic field lines were measured. Upward-moving electrons below 1-keV energy were dominant and were equivalent to a net downward electric current that fluctuated between .2 and .6 microamp/sq m during the flight above 130 km. As the rocket traversed this broad region of downward electric current over and to the north of the auroral forms, the horizontal electric field slowly rotated from east to west. The magnetic measurements indicate that the westward electrojet was a horizontal sheet of current several hundred kilometers in north-south extent.

Dark sector impact on gravitational collapse of an electrically charged scalar field

NASA Astrophysics Data System (ADS)

Nakonieczna, Anna; Rogatko, Marek; Nakonieczny, Łukasz

2015-11-01

Dark matter and dark energy are dominating components of the Universe. Their presence affects the course and results of processes, which are driven by the gravitational interaction. The objective of the paper was to examine the influence of the dark sector on the gravitational collapse of an electrically charged scalar field. A phantom scalar field was used as a model of dark energy in the system. Dark matter was modeled by a complex scalar field with a quartic potential, charged under a U(1)-gauge field. The dark components were coupled to the electrically charged scalar field via the exponential coupling and the gauge field-Maxwell field kinetic mixing, respectively. Complete non-linear simulations of the investigated process were performed. They were conducted from regular initial data to the end state, which was the matter dispersal or a singularity formation in a spacetime. During the collapse in the presence of dark energy dynamical wormholes and naked singularities were formed in emerging spacetimes. The wormhole throats were stabilized by the violation of the null energy condition, which occurred due to a significant increase of a value of the phantom scalar field function in its vicinity. The square of mass parameter of the dark matter scalar field potential controlled the formation of a Cauchy horizon or wormhole throats in the spacetime. The joint impact of dark energy and dark matter on the examined process indicated that the former decides what type of an object forms, while the latter controls the amount of time needed for the object to form. Additionally, the dark sector suppresses the natural tendency of an electrically charged scalar field to form a dynamical Reissner-Nordström spacetime during the gravitational collapse.

Electric field effect on exchange interaction in ultrathin Co films with ionic liquids

NASA Astrophysics Data System (ADS)

Ishibashi, Mio; Yamada, Kihiro T.; Shiota, Yoichi; Ando, Fuyuki; Koyama, Tomohiro; Kakizakai, Haruka; Mizuno, Hayato; Miwa, Kazumoto; Ono, Shimpei; Moriyama, Takahiro; Chiba, Daichi; Ono, Teruo

2018-06-01

Electric-field modulations of magnetic properties have been extensively studied not only for practical applications but also for fundamental interest. In this study, we investigated the electric field effect on the exchange interaction in ultrathin Co films with ionic liquids. The exchange coupling J was characterized from the direct magnetization measurement as a function of temperature using Pt/ultrathin Co/MgO structures. The trend of the electric field effect on J is in good agreement with that of the theoretical prediction, and a large change in J by applying a gate voltage was observed by forming an electric double layer using ionic liquids.

Methods for controlling pore morphology in aerogels using electric fields and products thereof

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

Worsley, Marcus A.; Baumann, Theodore F.; Satcher, Jr., Joe H.

In one embodiment, an aerogel or xerogel includes column structures of a material having minor pores therein and major pores devoid of the material positioned between the column structures, where longitudinal axes of the major pores are substantially parallel to one another. In another embodiment, a method includes heating a sol including aerogel or xerogel precursor materials to cause gelation thereof to form an aerogel or xerogel and exposing the heated sol to an electric field, wherein the electric field causes orientation of a microstructure of the sol during gelation, which is retained by the aerogel or xerogel. In onemore » approach, an aerogel has elongated pores extending between a material arranged in column structures having structural characteristics of being formed from a sol exposed to an electric field that causes orientation of a microstructure of the sol during gelation which is retained by the elongated pores of the aerogel.« less

Electric Field-Controlled Ion Transport In TiO2 Nanochannel.

PubMed

Li, Dan; Jing, Wenheng; Li, Shuaiqiang; Shen, Hao; Xing, Weihong

2015-06-03

On the basis of biological ion channels, we constructed TiO2 membranes with rigid channels of 2.3 nm to mimic biomembranes with flexible channels; an external electric field was employed to regulate ion transport in the confined channels at a high ionic strength in the absence of electrical double layer overlap. Results show that transport rates for both Na+ and Mg2+ were decreased irrespective of the direction of the electric field. Furthermore, a voltage-gated selective ion channel was formed, the Mg2+ channel closed at -2 V, and a reversed relative electric field gradient was at the same order of the concentration gradient, whereas the Na+ with smaller Stokes radius and lower valence was less sensitive to the electric field and thus preferentially occupied and passed the channel. Thus, when an external electric field is applied, membranes with larger nanochannels have promising applications in selective separation of mixture salts at a high concentration.

Dielectrophoresis-magnetophoresis force driven magnetic nanoparticle movement in transformer oil based magnetic fluids.

PubMed

Lee, Jong-Chul; Lee, Sangyoup

2013-09-01

Magnetic fluid is a stable colloidal mixture contained magnetic nanoparticles coated with a surfactant. Recently, it was found that the fluid has properties to increase heat transfer and dielectric characteristics due to the added magnetic nanoparticles in transformer oils. The magnetic nanoparticles in the fluid experience an electrical force directed toward the place of maximum electric field strength when the electric field is applied. And when the external magnetic field is applied, the magnetic nanoparticles form long chains oriented along the direction of the field. The behaviors of magnetic nanoparticles in both the fields must play an important role in changing the heat transfer and dielectric characteristics of the fluids. In this study, we visualized the movement of magnetic nanoparticles influenced by both the fields applied in-situ. It was found that the magnetic nanoparticles travel in the region near the electrode by the electric field and form long chains along the field direction by the magnetic field. It can be inferred that the movement of magnetic nanoparticles appears by both the fields, and the breakdown voltage of transformer oil based magnetic fluids might be influenced according to the dispersion of magnetic nanoparticles.

Convection Electric Field Observations by THEMIS and the Van Allen Probes

NASA Astrophysics Data System (ADS)

Califf, S.; Li, X.; Bonnell, J. W.; Wygant, J. R.; Malaspina, D.; Hartinger, M.; Thaller, S. A.

2013-12-01

We present direct electric field measurements made by THEMIS and the Van Allen Probes in the inner magnetosphere, focusing on the large-scale, near-DC convection electric field. The convection electric field drives plasma Earthward from the tail into the inner magnetosphere, playing a critical role in forming the ring current. Although it is normally shielded deep inside the magnetosphere, during storm times this large-scale electric field can penetrate to low L values (L < 3), eroding the plasmasphere and also providing a mechanism for ~100 keV electron injection into the slot region and inner radiation belt. The relationship of the convection electric field with the plasmasphere is also important for understanding the dynamic outer radiation belt, as the plasmapause boundary has been strongly correlated with the dynamic variation of the outer radiation belt electrons.

Electrostrictive Graft Elastomers

NASA Technical Reports Server (NTRS)

Su, Ji (Inventor); Harrison, Joycelyn S. (Inventor); St.Clair, Terry L. (Inventor)

2003-01-01

An electrostrictive graft elastomer has a backbone molecule which is a non-crystallizable, flexible macromolecular chain and a grafted polymer forming polar graft moieties with backbone molecules. The polar graft moieties have been rotated by an applied electric field, e.g., into substantial polar alignment. The rotation is sustained until the electric field is removed. In another embodiment, a process for producing strain in an elastomer includes: (a) providing a graft elastomer having a backbone molecule which is a non-crystallizable, flexible macromolecular chain and a grafted polymer forming polar graft moieties with backbone molecules; and (b) applying an electric field to the graft elastomer to rotate the polar graft moieties, e.g., into substantial polar alignment.

Electric and magnetic fields and tumor progression. Final report

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

Keng, P.C.; Grota, L.J.; Michaelson, S.

This laboratory study has rigorously investigated two previously reported biological effects of 60-Hz electric and magnetic fields. The first effect involves nighttime suppression of melatonin synthesis in the pineal glands of rats exposed to high electric fields. The second concerns the increase in colony forming ability of human colon cancer cells exposed to 1.4-G magnetic fields. Neither effect was detected in the present study. A series of published laboratory studies on rats reported that 60-Hz electric fields at various field levels up to 130 kV/m suppress the nighttime synthesis of melatonin, a hormone produced by the pineal gland. Since melatoninmore » is known to modulate the immune system and may inhibit cancer cell activity, changes in physiological levels of melatonin may have significant health consequences. In the repeat experiments, field exposure did not alter nighttime levels of melatonin or enzyme activities in the pineal gland. A small but statistically significant reduction of about 20% in serum melatonin was seen in exposed animals. Pineal melatonin was also unaffected by the presence of red light as a cofactor with field exposure or by time-shifting the daily field exposure period. Another study reported that 60-Hz magnetic fields can affect the colony forming ability of human cancer cells after exposure in a culture medium. In the repeat experiments, field exposure did not alter the colony forming ability of human Colo 205 cells in two different cell concentrations at plating or in two different incubation conditions. Field exposure also did not affect cell cycling in any of the four cell lines tested.« less

Distributed charging of electrical assets

DOEpatents

Ghosh, Soumyadip; Phan, Dung; Sharma, Mayank; Wu, Chai Wah; Xiong, Jinjun

2016-02-16

The present disclosure relates generally to the field of distributed charging of electrical assets. In various examples, distributed charging of electrical assets may be implemented in the form of systems, methods and/or algorithms.

Investigating the mechanism of aggregation of colloidal particles during electrophoretic deposition

NASA Astrophysics Data System (ADS)

Guelcher, Scott Arthur

Charged particles deposited near an electrode aggregate to form ordered clusters in the presence of both dc and ac applied electric fields. The aggregation process could have important applications in areas such as coatings technology and ceramics processing. This thesis has sought to identify the phenomena driving the aggregation process. According to the electroosmotic flow developed by Solomentsev et al. (1997), aggregation in dc electric fields is caused by convection in the electroosmotic flow about deposited particles, and it is therefore an electrokinetic phenomenon which scales linearly with the electric field and the zeta-potential of the particles. Trajectories of pairs of particles aggregating to form doublets have been shown to scale linearly with the electric field and the zeta-potential of the particles, as predicted by the electroosmotic flow model. Furthermore, quantitative agreement has been demonstrated between the experimental and calculated trajectories for surface-to-surface separation distances between the particles ranging from one to two radii. The trajectories were calculated from the electroosmotic flow model with no fitting parameters; the only inputs to the model were the mobility of the deposited particles, the zeta- potential of the particles, and the applied electric field, all of which were measured independently. Clustering of colloidal particles deposited near an electrode in ac fields has also been observed, but a suitable model for the aggregation process has not been proposed and quantitative data in the literature are scarce. Trajectories of pairs of particles aggregating to form doublets in an ac field have been shown to scale with the root-mean-square (rms) electric field raised to the power 1.4 over the range of electric fields 10-35 V/cm (100-Hz sine and square waves). The aggregation is also frequency dependent; the doublets aggregate fastest at 30 Hz (square wave) and slowest at 500 Hz (square wave), while the interaction is repulsive at 1 kHz (square wave). The advantage of ac fields is that the process can operated at frequencies sufficiently high to avoid the negative effects of electrochemical reactions.

Electrorheological crystallization of proteins and other molecules

DOEpatents

Craig, G.D.; Rupp, B.

1996-06-11

An electrorheological crystalline mass of a molecule is formed by dispersing the molecule in a dispersion fluid and subjecting the molecule dispersion to a uniform electrical field for a period of time during which time an electrorheological crystalline mass is formed. Molecules that may be used to form an electrorheological crystalline mass include any organic or inorganic molecule which has a permanent dipole and/or which is capable of becoming an induced dipole in the presence of an electric field. The molecules used to form the electrorheological crystalline mass are preferably macromolecules, such as biomolecules, such as proteins, nucleic acids, carbohydrates, lipoproteins and viruses. Molecules are crystallized by a method in which an electric field is maintained for a period of time after the electrorheological crystalline mass has formed during which time at least some of the molecules making up the electrorheological crystalline mass form a crystal lattice. The three dimensional structure of a molecule is determined by a method in which an electrorheological crystalline mass of the molecule is formed, an X-ray diffraction pattern of the electrorheological crystalline mass is obtained and the three dimensional structure of the molecule is calculated from the X-ray diffraction pattern. 4 figs.

Electrorheological crystallization of proteins and other molecules

DOEpatents

Craig, George D.; Rupp, Bernhard

1996-01-01

An electrorheological crystalline mass of a molecule is formed by dispersing the molecule in a dispersion fluid and subjecting the molecule dispersion to a uniform electrical field for a period of time during which time an electrorheological crystalline mass is formed. Molecules that may be used to form an electrorheological crystalline mass include any organic or inorganic molecule which has a permanent dipole and/or which is capable of becoming an induced dipole in the presence of an electric field. The molecules used to form the electrorheological crystalline mass are preferably macromolecules, such as biomolecules, such as proteins, nucleic acids, carbohydrates, lipoproteins and viruses. Molecules are crystallized by a method in which an electric field is maintained for a period of time after the electrorheological crystalline mass has formed during which time at least some of the molecules making up the electrorheological crystalline mass form a crystal lattice. The three dimensional structure of a molecule is determined by a method in which an electrorheological crystalline mass of the molecule is formed, an x-ray diffraction pattern of the electrorheological crystalline mass is obtained and the three dimensional structure of the molecule is calculated from the x-ray diffraction pattern.

One-dimensional nonlinear instability study of a slightly viscoelastic, perfectly conducting liquid jet under a radial electric field

NASA Astrophysics Data System (ADS)

Li, Fang; Yin, Xie-Yuan; Yin, Xie-Zhen

2016-05-01

A one-dimensional electrified viscoelastic model is built to study the nonlinear behavior of a slightly viscoelastic, perfectly conducting liquid jet under a radial electric field. The equations are solved numerically using an implicit finite difference scheme together with a boundary element method. The electrified viscoelastic jet is found to evolve into a beads-on-string structure in the presence of the radial electric field. Although the radial electric field greatly enhances the linear instability of the jet, its influence on the decay of the filament thickness is limited during the nonlinear evolution of the jet. On the other hand, the radial electric field induces axial non-uniformity of the first normal stress difference within the filament. The first normal stress difference in the center region of the filament may be greatly decreased by the radial electric field. The regions with/without satellite droplets are illuminated on the χ (the electrical Bond number)-k (the dimensionless wave number) plane. Satellite droplets may be formed for larger wave numbers at larger radial electric fields.

Combined calculi for photon orbital and spin angular momenta

NASA Astrophysics Data System (ADS)

Elias, N. M.

2014-08-01

Context. Wavelength, photon spin angular momentum (PSAM), and photon orbital angular momentum (POAM), completely describe the state of a photon or an electric field (an ensemble of photons). Wavelength relates directly to energy and linear momentum, the corresponding kinetic quantities. PSAM and POAM, themselves kinetic quantities, are colloquially known as polarization and optical vortices, respectively. Astrophysical sources emit photons that carry this information. Aims: PSAM characteristics of an electric field (intensity) are compactly described by the Jones (Stokes/Mueller) calculus. Similarly, I created calculi to represent POAM characteristics of electric fields and intensities in an astrophysical context. Adding wavelength dependence to all of these calculi is trivial. The next logical steps are to 1) form photon total angular momentum (PTAM = POAM + PSAM) calculi; 2) prove their validity using operators and expectation values; and 3) show that instrumental PSAM can affect measured POAM values for certain types of electric fields. Methods: I derive the PTAM calculi of electric fields and intensities by combining the POAM and PSAM calculi. I show how these quantities propagate from celestial sphere to image plane. I also form the PTAM operator (the sum of the POAM and PSAM operators), with and without instrumental PSAM, and calculate the corresponding expectation values. Results: Apart from the vector, matrix, dot product, and direct product symbols, the PTAM and POAM calculi appear superficially identical. I provide tables with all possible forms of PTAM calculi. I prove that PTAM expectation values are correct for instruments with and without instrumental PSAM. I also show that POAM measurements of "unfactored" PTAM electric fields passing through non-zero instrumental circular PSAM can be biased. Conclusions: The combined PTAM calculi provide insight into mathematically modeling PTAM sources and calibrating POAM- and PSAM-induced measurement errors.

Wireless Sensing System Using Open-circuit, Electrically-conductive Spiral-trace Sensor

NASA Technical Reports Server (NTRS)

Woodard, Stanley E. (Inventor); Taylor, Bryant D. (Inventor)

2013-01-01

A wireless sensing system includes a sensor made from an electrical conductor shaped to form an open-circuit, electrically-conductive spiral trace having inductance and capacitance. In the presence of a time-varying magnetic field, the sensor resonates to generate a harmonic response having a frequency, amplitude and bandwidth. A magnetic field response recorder wirelessly transmits the time-varying magnetic field to the sensor and wirelessly detects the sensor's response frequency, amplitude and bandwidth.

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

Lin, Meng-Lin; Peng, J. S.; Lee, Sanboh, E-mail: sblee@mx.nthu.edu.tw

We studied the digestive ripening of thiol-capped gold nanoparticles under simultaneous action of electric field and reflux heating in a silicone oil bath at 130 °C, using transmission electron microscopy. Observation revealed that a polydispersed gold nanoparticle system reached the state of nearly monodispersity under the action of an electric field and the thiol-capped gold nanoparticles carried negative charges. The electric field caused the increase of the particle size for the nearly monodispersed gold nanoparticle system. The self-assembly of the nearly monodisperse gold nanoparticles under the action of an electric field of a high field intensity was observed. The gold nanoparticlesmore » tended to form self-assembled nanostructures of six-fold symmetry. This study provides a new route for system engineering to control the particle size of metallic nanoparticles by electric field and digestive ripening.« less

Electric Field Effects in Self-Propagating High-Temperature Synthesis under Microgravity Conditions

NASA Technical Reports Server (NTRS)

Unuvar, C.; Frederick, D. M.; Shaw, B. D.; Munir, Z. A.

2003-01-01

Self-propagating high-temperature synthesis (SHS) has been used to form many materials. SHS generally involves mixing reactants together (e.g., metal powders) and igniting the mixture such that a combustion (deflagration) wave passes though the mixture. The imposition of an electric field (AC or DC) across SHS reactants has been shown to have a marked effect on the dynamics of wave propagation and on the nature, composition, and homogeneity of the product . The use of an electric field with SHS has been termed "field-assisted SHS". Combustion wave velocities and temperatures are directly affected by the field, which is typically perpendicular to the average wave velocity. The degree of activation by the field (e.g., combustion rate) is related to the current density distribution within the sample, and is therefore related to the temperature-dependent spatial distribution of the effective electrical conductivity of reactants and products. Furthermore, the field can influence other important SHS-related phenomena including capillary flow, mass-transport in porous media, and Marangoni flows. These phenomena are influenced by gravity in conventional SHS processes (i.e., without electric fields). As a result the influence of the field on SHS under reduced gravity is expected to be different than under normal gravity. It is also known that heat loss rates from samples, which can depend significantly on gravity, can influence final products in SHS. This research program is focused on studying field-assisted SHS under reduced gravity conditions. The broad objective of this research program is to understand the role of an electric field in SHS reactions under conditions where gravity-related effects are suppressed. The research will allow increased understanding of fundamental aspects of field-assisted SHS processes as well as synthesis of materials that cannot be formed in normal gravity.

Method and apparatus for atomization and spraying of molten metals

DOEpatents

Hobson, David O.; Alexeff, Igor; Sikka, Vinod K.

1990-01-01

A method and device for dispersing molten metal into fine particulate spray, the method comprises applying an electric current through the molten metal and simultaneously applying a magnetic field to the molten metal in a plane perpendicular to the electric current, whereby the molten metal is caused to form into droplets at an angle perpendicular to both the electric current and the magnetic field. The device comprises a structure for providing a molten metal, appropriately arranged electrodes for applying an electric current through the molten metal, and a magnet for providing a magnetic field in a plane perpendicular to the electric current.

Method and apparatus for atomization and spraying of molten metals

DOEpatents

Hobson, D.O.; Alexeff, I.; Sikka, V.K.

1988-07-19

A method and device for dispersing molten metal into fine particulate spray, the method comprises applying an electric current through the molten metal and simultaneously applying a magnetic field to the molten metal in a plane perpendicular to the electric current, whereby the molten metal is caused to form into droplets at an angle perpendicular to both the electric current and the magnetic field. The device comprises a structure for providing a molten metal, appropriately arranged electrodes for applying an electric current through the molten metal, and a magnet for providing a magnetic field in a plane perpendicular to the electric current. 11 figs.

Mechanics of water pore formation in lipid membrane under electric field

NASA Astrophysics Data System (ADS)

Bu, Bing; Li, Dechang; Diao, Jiajie; Ji, Baohua

2017-04-01

Transmembrane water pores are crucial for substance transport through cell membranes via membrane fusion, such as in neural communication. However, the molecular mechanism of water pore formation is not clear. In this study, we apply all-atom molecular dynamics and bias-exchange metadynamics simulations to study the process of water pore formation under an electric field. We show that water molecules can enter a membrane under an electric field and form a water pore of a few nanometers in diameter. These water molecules disturb the interactions between lipid head groups and the ordered arrangement of lipids. Following the movement of water molecules, the lipid head groups are rotated and driven into the hydrophobic region of the membrane. The reorientated lipid head groups inside the membrane form a hydrophilic surface of the water pore. This study reveals the atomic details of how an electric field influences the movement of water molecules and lipid head groups, resulting in water pore formation.

Dependence of nuclear quadrupole resonance transitions on the electric field gradient asymmetry parameter for nuclides with half-integer spins

DOE PAGES

Cho, Herman

2016-02-28

Allowed transition energies and eigenstate expansions have been calculated and tabulated in numerical form as functions of the electric field gradient asymmetry parameter for the zero field Hamiltonian of quadrupolar nuclides with I = 3/2,5/2,7/2, and 9/2. These results are essential to interpret nuclear quadrupole resonance (NQR) spectra and extract accurate values of the electric field gradient tensors. Furthermore, applications of NQR methods to studies of electronic structure in heavy element systems are proposed.

Lattice calculation of electric dipole moments and form factors of the nucleon

NASA Astrophysics Data System (ADS)

Abramczyk, M.; Aoki, S.; Blum, T.; Izubuchi, T.; Ohki, H.; Syritsyn, S.

2017-07-01

We analyze commonly used expressions for computing the nucleon electric dipole form factors (EDFF) F3 and moments (EDM) on a lattice and find that they lead to spurious contributions from the Pauli form factor F2 due to inadequate definition of these form factors when parity mixing of lattice nucleon fields is involved. Using chirally symmetric domain wall fermions, we calculate the proton and the neutron EDFF induced by the C P -violating quark chromo-EDM interaction using the corrected expression. In addition, we calculate the electric dipole moment of the neutron using a background electric field that respects time translation invariance and boundary conditions, and we find that it decidedly agrees with the new formula but not the old formula for F3. Finally, we analyze some selected lattice results for the nucleon EDM and observe that after the correction is applied, they either agree with zero or are substantially reduced in magnitude, thus reconciling their difference from phenomenological estimates of the nucleon EDM.

Relation Between Lightning Activity of Summer and Winter Thunderclouds and Surface Electric Field Variation, Japan

NASA Technical Reports Server (NTRS)

Michimoto, K.; Shimura, T.; Suzuki, T.

1999-01-01

In winter, active convective clouds frequently form along the coastline of the Hokuriku district, in association with strong advection of Siberian air masses over the Sea of Japan. On the other hand, in summer, many thunderclouds form in the Kanto region in the afternoon every day. Summer and winter thunderclouds were investigated by field works, operation of the C- and X-band weather radars and a car-borne fieldmill. The investigation found a very close relation between the temporal variation of 3-dimensional radar echo and surface electric field magnitude detected by a car-borne fieldmill in the case of summer thunderclouds and winter convective clouds or thunderclouds. The study probed the close relation among radar echoes, quantity of thunderclouds and surface electric field magnitude in the summer and winter seasons. We think that summer thundercloud activity can basically be equated with winter thundercloud lightning activity, except that the magnitude of surface electric field under summer thunderclouds in the case of the Kanto region cannot be equated with that under winter thunderclouds in the case of the Hokuriku district in winter.

Electrical properties of PMMA ion-implanted with low-energy Si+ beam

NASA Astrophysics Data System (ADS)

Hadjichristov, G. B.; Gueorguiev, V. K.; Ivanov, Tz E.; Marinov, Y. G.; Ivanov, V. G.; Faulques, E.

2010-01-01

The electrical properties of polymethylmethacrylate (PMMA) after implantation with silicon ions accelerated to an energy of 50 keV are studied under DC electric bias field. The electrical response of the formed material is examined as a function of Si+ fluence in the range 1014 - 1017 cm-2. The carbonaceous subsurface region of the Si+-implanted PMMA displays a significant DC conductivity and a sizable field effect that can be used for electronic applications.

Scalable Electrospray Components for Portable Power Applications Using MEMS Fabrication Techniques

DTIC Science & Technology

2006-11-01

electric field induced between the electrode and the conducting liquid initially causes a Taylor cone to form at the tip of the tube where the field...voltage source, creating a strong electrical potential difference between the two. A Taylor -cone forms at the tip of each nozzle from the electro...Combustion Institute, 20, pp. 965-972. Muler, N. and Fréchette, L.G., 2002: Performance Analysis of Brayton and Rankine Cycle Microsystems for

Radiation Shielding System Using a Composite of Carbon Nanotubes Loaded with Electropolymers

NASA Technical Reports Server (NTRS)

McKay, Chris; Chen, Bin

2012-01-01

Single-wall carbon nanotubes (SWCNTs) coated with a hydrogen-rich, electrically conducting polymer such as polyethylene, receive and dissipate a portion of incoming radiation pulse energy to electrical signals that are transmitted along the CNT axes, and are received at energy-dissipating terminals. In this innovation, an array of highly aligned nanowires is grown using a strong electric field or another suitable orientation procedure. Polyethylene (PE), polymethymlethacrylate (PMMA), or other electrically conducting polymer is spin-coated onto the SWCNTs with an average thickness of a few hundred nanometers to a few tenths of micrometers to form a PE/SWCNT composite. Alternatively, the polymer is spin-coated onto the nanowire array or an anodized alumina membrane (AAM) to form a PE/metal core shell structure, or PE can be electropolymerized using the SWCNTs or the metal nanowires as an electrode to form a PE/SWCNT core shell structure. The core shell structures can be extruded as anisotropic fibers. A monomer can be polymerized in the presence of SWCNTs to form highly cross-linked PE/SWCNT films. Alternatively, Pb colloid solution can be impregnated into a three-dimensional PE/SWCNT nanostructure to form a PW/SWCNT/Pb composite structure. A face-centered cubic (FCC) arrangement provides up to 12 interconnection channels connected to each core, with transverse channel dimensions up to 20 nm, with adequate mechanical compressive strength, and with an associated electrical conductivity of around 3 Seimens/cm for currents ranging from 0.01 to 10 mA. This threedimensional nanostructure is used as a host material to house appropriate radiation shielding material such as hydrogen- rich polymer/CNT structures, metal nanoparticles, and nanowires. Thicknesses of this material required to attenuate 10 percent, 50 percent, and 90 percent of an incident beam (gamma, X-ray, ultraviolet, neutron, proton, and electron) at energies in the range of 0 440 MeV are being determined, for example, by measuring fluence rate reduction. For example, a radiation field arrives first at an exposed surface of the innovation and produces an associated first electric field within the metal-like fingers of the three-dimensional nanostructure. This field is intensified near the exposed tips of the fingers, and this intensified field generates an intensified second electric field near the adjacent exposed tips of the coated CNSs. This generates an associated electrical current in the CNSs, and the associated electropolymer coating. The current is received by the second substrate transport component and is transported to the dissipation mechanism located contiguously to the second substrate.

Electromagnetic coupling of spins and pseudospins in bilayer graphene

NASA Astrophysics Data System (ADS)

Winkler, R.; Zülicke, U.

2015-03-01

We present a theoretical study of bilayer-graphene's electronic properties in the presence of electric and magnetic fields. In contrast to known materials, including single-layer graphene, any possible coupling of physical quantities to components of the electric field has a counterpart where the analogous component of the magnetic field couples to exactly the same quantities. For example, a purely electric spin splitting appears as the magneto-electric analogue of the magnetic Zeeman spin splitting. The measurable thermodynamic response induced by magnetic and electric fields is thus completely symmetric. The Pauli magnetization induced by a magnetic field takes exactly the same functional form as the polarization induced by an electric field. Although they seem counterintuitive, our findings are consistent with fundamental principles such as time reversal symmetry. For example, only a magnetic field can give rise to a macroscopic spin polarization, whereas only a perpendicular electric field can induce a macroscopic polarization of the sublattice-related pseudospin in bilayer graphene. These rules enforced by symmetry for the matter-field interactions clarify the nature of spins versus pseudospins. We have obtained numerical values of prefactors for relevant terms. NSF Grant DMR-1310199 and Marsden Fund Contract No. VUW0719.

High-order harmonic generation driven by inhomogeneous plasmonics fields spatially bounded: influence on the cut-off law

NASA Astrophysics Data System (ADS)

Neyra, E.; Videla, F.; Ciappina, M. F.; Pérez-Hernández, J. A.; Roso, L.; Lewenstein, M.; Torchia, G. A.

2018-03-01

We study high-order harmonic generation (HHG) in model atoms driven by plasmonic-enhanced fields. These fields result from the illumination of plasmonic nanostructures by few-cycle laser pulses. We demonstrate that the spatial inhomogeneous character of the laser electric field, in a form of Gaussian-shaped functions, leads to an unexpected relationship between the HHG cutoff and the laser wavelength. Precise description of the spatial form of the plasmonic-enhanced field allows us to predict this relationship. We combine the numerical solutions of the time-dependent Schrödinger equation (TDSE) with the plasmonic-enhanced electric fields obtained from 3D finite element simulations. We additionally employ classical simulations to supplement the TDSE outcomes and characterize the extended HHG spectra by means of their associated electron trajectories. A proper definition of the spatially inhomogeneous laser electric field is instrumental to accurately describe the underlying physics of HHG driven by plasmonic-enhanced fields. This characterization opens up new perspectives for HHG control with various experimental nano-setups.

Structured DC Electric Fields With and Without Associated Plasma Density Gradients Observed with the C/NOFS Satellite

NASA Technical Reports Server (NTRS)

Pfaff, R.; Rowland, D.; Klenzing, J.; Freudenreich, H.; Bromund, K.; Liebrecht, C.; Roddy, P.; Hunton, D.

2009-01-01

DC electric field observations and associated plasma drifts gathered with the Vector Electric Field Investigation on the Air Force Communication/Navigation Outage Forecasting System (C/NOFS) satellite typically reveal considerable variation at large scales (approximately 100's of km), in both daytime and nighttime cases, with enhanced structures usually confined to the nightside. Although such electric field structures are typically associated with plasma density depletions and structures, as observed by the Planar Langmuir Probe on C/NOFS, what is surprising is the number of cases in which large amplitude, structured DC electric fields are observed without a significant plasma density counterpart structure, including their appearance at times when the ambient plasma density appears relatively quiescent. We investigate the relationship of such structured DC electric fields and the ambient plasma density in the C/NOFS satellite measurements observed thus far, taking into account both plasma density depletions and enhancements. We investigate the mapping of the electric fields along magnetic field lines from distant altitudes and latitudes to locations where the density structures, which presumably formed the original seat of the electric fields, are no longer discernible in the observations. In some cases, the electric field structures and spectral characteristics appear to mimic those associated with equatorial spread-F processes, providing important clues to their origins. We examine altitude, seasonal, and longitudinal effects in an effort to establish the origin of such structured DC electric fields observed both with, and without, associated plasma density gradients

Low-frequency RF Coupling To Unconventional (Fat Unbalanced) Dipoles

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

Ong, M M; Brown, C G; Perkins, M P

2010-12-07

The report explains radio frequency (RF) coupling to unconventional dipole antennas. Normal dipoles have thin equal length arms that operate at maximum efficiency around resonance frequencies. In some applications like high-explosive (HE) safety analysis, structures similar to dipoles with ''fat'' unequal length arms must be evaluated for indirect-lightning effects. An example is shown where a metal drum-shaped container with HE forms one arm and the detonator cable acts as the other. Even if the HE is in a facility converted into a ''Faraday cage'', a lightning strike to the facility could still produce electric fields inside. The detonator cable concentratesmore » the electric field and carries the energy into the detonator, potentially creating a hazard. This electromagnetic (EM) field coupling of lightning energy is the indirect effect of a lightning strike. In practice, ''Faraday cages'' are formed by the rebar of the concrete facilities. The individual rebar rods in the roof, walls and floor are normally electrically connected because of the construction technique of using metal wire to tie the pieces together. There are two additional requirements for a good cage. (1) The roof-wall joint and the wall-floor joint must be electrically attached. (2) All metallic penetrations into the facility must also be electrically connected to the rebar. In this report, it is assumed that these conditions have been met, and there is no arcing in the facility structure. Many types of detonators have metal ''cups'' that contain the explosives and thin electrical initiating wires, called bridge wires mounted between two pins. The pins are connected to the detonator cable. The area of concern is between the pins supporting the bridge wire and the metal cup forming the outside of the detonator. Detonator cables usually have two wires, and in this example, both wires generated the same voltage at the detonator bridge wire. This is called the common-mode voltage. The explosive component inside a detonator is relatively sensitive, and any electrical arc is a concern. In a safety analysis, the pin-to-cup voltage, i.e., detonator voltage, must be calculated to decide if an arc will form. If the electric field is known, the voltage between any two points is simply the integral of the field along a line between the points. Eq. 1.1. For simplicity, it is assumed that the electric field and dipole elements are aligned. Calculating the induced detonator voltage is more complex because of the field concentration caused by metal components. If the detonator cup is not electrically connected to the metal HE container, the portion of the voltage generated by the dipole at the detonator will divide between the container-to-cup and cup-to-pin gaps. The gap voltages are determined by their capacitances. As a simplification, it will be assumed the cup is electrically attached, short circuited, to the HE container. The electrical field in the pin-to-cup area is determined by the field near the dipole, the length of the dipole, the shape of the arms, and the orientation of the arms. Given the characteristics of a lightning strike and the inductance of the facility, the electric fields in the ''Faraday cage'' can be calculated. The important parameters for determining the voltage in an empty facility are the inductance of the rebars and the rate of change of the current, Eq. 1.3. The internal electric fields are directly related to the facility voltages, however, the electric fields in the pin-to-cup space is much higher than the facility fields because the antenna will concentrate the fields covered by the arms. Because the lightning current rise-time is different for every strike, the maximum electric field and the induced detonator voltage should be described by probability distributions. For pedantic purposes, the peak field in the simulations will be simply set to 1 V/m. Lightning induced detonator voltages can be calculated by scaling up with the facility fields. Any metal object around the explosives, such as a work stand, will also distort the electric fields. A computer simulation of the electric fields in a facility with a work stand and HE container is shown. In this configuration, the work stand is grounded, and the intensity of field around the HE (denoted in dark blue) is reduced relative to the rest of the work bay (denoted lighter blue). The area above work stand posts has much higher fields indicated by red. The fields on top of the container are also affected. Without an understanding of how the electric fields are distributed near the detonator cable and container, it is not possible to calculate the induced detonator voltage. The average lightning current has rise- and fall-times of 3 us and 50 us respectively, and this translates to a wavelength that is long when compared with the length of the HE container or detonator cable.« less

Hidden momentum and the Abraham-Minkowski debate

NASA Astrophysics Data System (ADS)

Saldanha, Pablo L.; Filho, J. S. Oliveira

2017-04-01

We use an extended version of electrodynamics, which admits the existence of magnetic charges and currents, to discuss how different models for electric and magnetic dipoles do or do not carry hidden momentum under the influence of external electromagnetic fields. Based on that, we discuss how the models adopted for the electric and magnetic dipoles from the particles that compose a material medium influence the expression for the electromagnetic part of the light momentum in the medium. We show that Abraham expression is compatible with electric dipoles formed by electric charges and magnetic dipoles formed by magnetic charges, while Minkowski expression is compatible with electric dipoles formed by magnetic currents and magnetic dipoles formed by electric currents. The expression ɛ0E ×B , on the other hand, is shown to be compatible with electric dipoles formed by electric charges and magnetic dipoles formed by electric currents, which are much more natural models. So this expression has an interesting interpretation in the Abraham-Minkowski debate about the momentum of light in a medium: It is the expression compatible with the nonexistence of magnetic charges. We also provide a simple justification of why Abraham and Minkowski momenta can be associated with the kinetic and canonical momentum of light, respectively.

Physical deposition behavior of stiff amphiphilic polyelectrolytes in an external electric field

NASA Astrophysics Data System (ADS)

Hu, Dongmei; Zuo, Chuncheng; Cao, Qianqian; Chen, Hongli

2017-08-01

Coarse-grained molecular dynamics simulations are conducted to study the physical deposition behavior of stiff amphiphilic polyelectrolytes (APEs) in an external electric field. The effects of chain stiffness, the charge distribution of a hydrophilic block, and electric field strength are investigated. Amphiphilic multilayers, which consist of a monolayer of adsorbed hydrophilic monomers (HLMs), a hydrophobic layer, and another hydrophilic layer, are formed in a selective solvent. All cases exhibit locally ordered hydrophilic monolayers. Two kinds of hydrophobic micelles are distinguished based on local structures. Stripe and network hydrophobic patterns are formed in individual cases. Increasing the chain stiffness decreases the thickness of the deposited layer, the lateral size of the hydrophobic micelles, and the amount of deposition. Increasing the number of positively charged HLMs in a single chain has the same effect as increasing chain stiffness. Moreover, when applied normally to the substrate, the electric field compresses the deposited structures and increases the amount of deposition by pulling more PEs toward the substrate. A stronger electric field also facilitates the formation of a thinner and more ordered hydrophilic adsorption layer. These estimates help us explore how to tailor patterned nano-surfaces, nano-interfaces, or amphiphilic nanostructures by physically depositing semi-flexible APEs which is of crucial importance in physical sciences, life sciences and nanotechnology.

Electro-Acoustic Behavior of the Mitotic Spindle: A Semi-Classical Coarse-Grained Model

PubMed Central

Havelka, Daniel; Kučera, Ondřej; Deriu, Marco A.; Cifra, Michal

2014-01-01

The regulation of chromosome separation during mitosis is not fully understood yet. Microtubules forming mitotic spindles are targets of treatment strategies which are aimed at (i) the triggering of the apoptosis or (ii) the interruption of uncontrolled cell division. Despite these facts, only few physical models relating to the dynamics of mitotic spindles exist up to now. In this paper, we present the first electromechanical model which enables calculation of the electromagnetic field coupled to acoustic vibrations of the mitotic spindle. This electromagnetic field originates from the electrical polarity of microtubules which form the mitotic spindle. The model is based on the approximation of resonantly vibrating microtubules by a network of oscillating electric dipoles. Our computational results predict the existence of a rapidly changing electric field which is generated by either driven or endogenous vibrations of the mitotic spindle. For certain values of parameters, the intensity of the electric field and its gradient reach values which may exert a not-inconsiderable force on chromosomes which are aligned in the spindle midzone. Our model may describe possible mechanisms of the effects of ultra-short electrical and mechanical pulses on dividing cells—a strategy used in novel methods for cancer treatment. PMID:24497952

Fuel cell assembly unit for promoting fluid service and electrical conductivity

DOEpatents

Jones, Daniel O.

1999-01-01

Fluid service and/or electrical conductivity for a fuel cell assembly is promoted. Open-faced flow channel(s) are formed in a flow field plate face, and extend in the flow field plate face between entry and exit fluid manifolds. A resilient gas diffusion layer is located between the flow field plate face and a membrane electrode assembly, fluidly serviced with the open-faced flow channel(s). The resilient gas diffusion layer is restrained against entering the open-faced flow channel(s) under a compressive force applied to the fuel cell assembly. In particular, a first side of a support member abuts the flow field plate face, and a second side of the support member abuts the resilient gas diffusion layer. The support member is formed with a plurality of openings extending between the first and second sides of the support member. In addition, a clamping pressure is maintained for an interface between the resilient gas diffusion layer and a portion of the membrane electrode assembly. Preferably, the support member is spikeless and/or substantially flat. Further, the support member is formed with an electrical path for conducting current between the resilient gas diffusion layer and position(s) on the flow field plate face.

BiFeO3 Thin Films: A Playground for Exploring Electric-Field Control of Multifunctionalities

NASA Astrophysics Data System (ADS)

Yang, Jan-Chi; He, Qing; Yu, Pu; Chu, Ying-Hao

2015-07-01

A promising approach to the next generation of low-power, functional, and green nanoelectronics relies on advances in the electric-field control of lattice, charge, orbital, and spin degrees of freedom in novel materials. The possibility of electric-field control of these multiple materials functionalities offers interesting options across a range of modern technologies, including information communication, computing processes, data storage, active components, and functional electronics. This article reviews electric-field control and modulation of various degrees of freedom through the medium of multiferroic BiFeO3. Coexisting order parameters and inherent couplings in this materials system form a potent playground, enabling direct and indirect manipulation to obtain intriguing properties and functionalities with an electric stimulus. An in-depth understanding of those electrically controlled phenomena and breakthroughs is highlighted, paving a new route toward multifunctional nanoelectronics. This article concludes with a brief discussion on foreseeable challenges as well as future directions.

Electric field measuring and display system. [for cloud formations

NASA Technical Reports Server (NTRS)

Wojtasinski, R. J.; Lovall, D. D. (Inventor)

1974-01-01

An apparatus is described for monitoring the electric fields of cloud formations within a particular area. It utilizes capacitor plates that are alternately shielded from the clouds for generating an alternating signal corresponding to the intensity of the electric field of the clouds. A synchronizing signal is produced for controlling sampling of the alternating signal. Such samplings are fed through a filter and converted by an analogue to digital converter into digital form and subsequently fed to a transmitter for transmission to the control station for recording.

Frequency Response Calculations of Input Characteristics of Cavity-Backed Aperture Antennas Using AWE with Hybrid FEM/MoM Technique

NASA Technical Reports Server (NTRS)

Reddy, C. J.; Deshpande, M. D.

1997-01-01

Application of Asymptotic Waveform Evaluation (AWE) is presented in conjunction with a hybrid Finite Element Method (FEM)/Method of Moments (MoM) technique to calculate the input characteristics of cavity-backed aperture antennas over a frequency range. The hybrid FEM/MoM technique is used to form an integro-partial-differential equation to compute the electric field distribution of the cavity-backed aperture antenna. The electric field, thus obtained, is expanded in a Taylor series around the frequency of interest. The coefficients of 'Taylor series (called 'moments') are obtained using the frequency derivatives of the integro-partial-differential Equation formed by the hybrid FEM/MoM technique. Using the moments, the electric field in the cavity is obtained over a frequency range. Using the electric field at different frequencies, the input characteristics of the antenna are obtained over a wide frequency band. Numerical results for an open coaxial line, probe fed cavity, and cavity-backed microstrip patch antennas are presented. Good agreement between AWE and the exact solution over the frequency range is observed.

Application of Model Based Parameter Estimation for Fast Frequency Response Calculations of Input Characteristics of Cavity-Backed Aperture Antennas Using Hybrid FEM/MoM Technique

NASA Technical Reports Server (NTRS)

Reddy C. J.

1998-01-01

Model Based Parameter Estimation (MBPE) is presented in conjunction with the hybrid Finite Element Method (FEM)/Method of Moments (MoM) technique for fast computation of the input characteristics of cavity-backed aperture antennas over a frequency range. The hybrid FENI/MoM technique is used to form an integro-partial- differential equation to compute the electric field distribution of a cavity-backed aperture antenna. In MBPE, the electric field is expanded in a rational function of two polynomials. The coefficients of the rational function are obtained using the frequency derivatives of the integro-partial-differential equation formed by the hybrid FEM/ MoM technique. Using the rational function approximation, the electric field is obtained over a frequency range. Using the electric field at different frequencies, the input characteristics of the antenna are obtained over a wide frequency range. Numerical results for an open coaxial line, probe-fed coaxial cavity and cavity-backed microstrip patch antennas are presented. Good agreement between MBPE and the solutions over individual frequencies is observed.

Lattice calculation of electric dipole moments and form factors of the nucleon

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

Abramczyk, M.; Aoki, S.; Blum, T.

In this paper, we analyze commonly used expressions for computing the nucleon electric dipole form factors (EDFF)more » $$F_3$$ and moments (EDM) on a lattice and find that they lead to spurious contributions from the Pauli form factor $$F_2$$ due to inadequate definition of these form factors when parity mixing of lattice nucleon fields is involved. Using chirally symmetric domain wall fermions, we calculate the proton and the neutron EDFF induced by the CP-violating quark chromo-EDM interaction using the corrected expression. In addition, we calculate the electric dipole moment of the neutron using a background electric field that respects time translation invariance and boundary conditions, and we find that it decidedly agrees with the new formula but not the old formula for $$F_3$$. In conclusion, we analyze some selected lattice results for the nucleon EDM and observe that after the correction is applied, they either agree with zero or are substantially reduced in magnitude, thus reconciling their difference from phenomenological estimates of the nucleon EDM.« less

Lattice calculation of electric dipole moments and form factors of the nucleon

DOE PAGES

Abramczyk, M.; Aoki, S.; Blum, T.; ...

2017-07-10

In this paper, we analyze commonly used expressions for computing the nucleon electric dipole form factors (EDFF)more » $$F_3$$ and moments (EDM) on a lattice and find that they lead to spurious contributions from the Pauli form factor $$F_2$$ due to inadequate definition of these form factors when parity mixing of lattice nucleon fields is involved. Using chirally symmetric domain wall fermions, we calculate the proton and the neutron EDFF induced by the CP-violating quark chromo-EDM interaction using the corrected expression. In addition, we calculate the electric dipole moment of the neutron using a background electric field that respects time translation invariance and boundary conditions, and we find that it decidedly agrees with the new formula but not the old formula for $$F_3$$. In conclusion, we analyze some selected lattice results for the nucleon EDM and observe that after the correction is applied, they either agree with zero or are substantially reduced in magnitude, thus reconciling their difference from phenomenological estimates of the nucleon EDM.« less

Plasma rotation by electric and magnetic fields in a discharge cylinder

NASA Technical Reports Server (NTRS)

Wilhelm, H. E.; Hong, S. H.

1977-01-01

A theoretical model for an electric discharge consisting of a spatially diverging plasma sustained electrically between a small ring cathode and a larger ring anode in a cylindrical chamber with an axial magnetic field is developed to study the rotation of the discharge plasma in the crossed electric and magnetic fields. The associated boundary-value problem for the coupled partial differential equations which describe the electric potential and the plasma velocity fields is solved in closed form. The electric field, current density, and velocity distributions are discussed in terms of the Hartmann number and the Hall coefficient. As a result of Lorentz forces, the plasma rotates with speeds as high as 1 million cm/sec around its axis of symmetry at typical conditions. As an application, it is noted that rotating discharges of this type could be used to develop a high-density plasma-ultracentrifuge driven by j x B forces, in which the lighter (heavier) ion and atom components would be enriched in (off) the center of the discharge cylinder.

Electric field controlled emulsion phase contactor

DOEpatents

Scott, Timothy C.

1995-01-01

A system for contacting liquid phases comprising a column for transporting a liquid phase contacting system, the column having upper and lower regions. The upper region has a nozzle for introducing a dispersed phase and means for applying thereto a vertically oriented high intensity pulsed electric field. This electric field allows improved flow rates while shattering the dispersed phase into many micro-droplets upon exiting the nozzle to form a dispersion within a continuous phase. The lower region employs means for applying to the dispersed phase a horizontally oriented high intensity pulsed electric field so that the dispersed phase undergoes continuous coalescence and redispersion while being urged from side to side as it progresses through the system, increasing greatly the mass transfer opportunity.

Method of using an electric field controlled emulsion phase contactor

DOEpatents

Scott, Timothy C.

1993-01-01

A system for contacting liquid phases comprising a column for transporting a liquid phase contacting system, the column having upper and lower regions. The upper region has a nozzle for introducing a dispersed phase and means for applying thereto a vertically oriented high intensity pulsed electric field. This electric field allows improved flow rates while shattering the dispersed phase into many micro-droplets upon exiting the nozzle to form a dispersion within a continuous phase. The lower region employs means for applying to the dispersed phase a horizontally oriented high intensity pulsed electric field so that the dispersed phase undergoes continuous coalescence and redispersion while being urged from side to side as it progresses through the system, increasing greatly the mass transfer opportunity.

Electric field controlled emulsion phase contactor

DOEpatents

Scott, T.C.

1995-01-31

A system is described for contacting liquid phases comprising a column for transporting a liquid phase contacting system, the column having upper and lower regions. The upper region has a nozzle for introducing a dispersed phase and means for applying thereto a vertically oriented high intensity pulsed electric field. This electric field allows improved flow rates while shattering the dispersed phase into many micro-droplets upon exiting the nozzle to form a dispersion within a continuous phase. The lower region employs means for applying to the dispersed phase a horizontally oriented high intensity pulsed electric field so that the dispersed phase undergoes continuous coalescence and redispersion while being urged from side to side as it progresses through the system, increasing greatly the mass transfer opportunity. 5 figs.

Is an electric field always a promoter of wetting? Electro-dewetting of metals by electrolytes probed by in situ X-ray nanotomography

DOE PAGES

Nave, Maryana I.; Gu, Yu; Karen Chen-Wiegart, Yu-Chen; ...

2017-01-05

We developed a special electrochemical cell enabling quantitative analysis andin situX-ray nanotomography of metal/electrolyte interfaces subject to corrosion. Using this cell and applying the nodoid model to describe menisci formed on tungsten wires during anodization, the evolution of the electrolyte surface tension, the concentration of reaction products, and the meniscus contact angle were studied. In contrast to the electrowetting effect, where the applied electric field decreases the contact angle of electrolytes, anodization of the tungsten wires increases the contact angle of the meniscus. Hence, an electric field favors dewetting rather than wetting of the newly formed surface. Finally, the discoveredmore » effect opens up new opportunities for the control of wetting phenomena and calls for the revision of existing theories of electrowetting.« less

Fabricating and using a micromachined magnetostatic relay or switch

NASA Technical Reports Server (NTRS)

Tai, Yu-Chong (Inventor); Wright, John A. (Inventor)

2001-01-01

A micromachined magnetostatic relay or switch includes a springing beam on which a magnetic actuation plate is formed. The springing beam also includes an electrically conductive contact. In the presence of a magnetic field, the magnetic material causes the springing beam to bend, moving the electrically conductive contact either toward or away from another contact, and thus creating either an electrical short-circuit or an electrical open-circuit. The switch is fabricated from silicon substrates and is particularly useful in forming a MEMs commutation and control circuit for a miniaturized DC motor.

Electric field induced sheeting and breakup of dielectric liquid jets

NASA Astrophysics Data System (ADS)

Khoshnevis, Ahmad; Tsai, Scott S. H.; Esmaeilzadeh, Esmaeil

2014-01-01

We report experimental observations of the controlled deformation of a dielectric liquid jet subjected to a local high-voltage electrostatic field in the direction normal to the jet. The jet deforms to the shape of an elliptic cylinder upon application of a normal electrostatic field. As the applied electric field strength is increased, the elliptic cylindrical jet deforms permanently into a flat sheet, and eventually breaks-up into droplets. We interpret this observation—the stretch of the jet is in the normal direction to the applied electric field—qualitatively using the Taylor-Melcher leaky dielectric theory, and develop a simple scaling model that predicts the critical electric field strength for the jet-to-sheet transition. Our model shows a good agreement with experimental results, and has a form that is consistent with the classical drop deformation criterion in the Taylor-Melcher theory. Finally, we statistically analyze the resultant droplets from sheet breakup, and find that increasing the applied electric field strength improves droplet uniformity and reduces droplet size.

Self-Aligned Growth of Organic Semiconductor Single Crystals by Electric Field.

PubMed

Kotsuki, Kenji; Obata, Seiji; Saiki, Koichiro

2016-01-19

We proposed a novel but facile method for growing organic semiconductor single-crystals via solvent vapor annealing (SVA) under electric field. In the conventional SVA growth process, nuclei of crystals appeared anywhere on the substrate and their crystallographic axes were randomly distributed. We applied electric field during the SVA growth of 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) on the SiO2/Si substrate on which a pair of electrodes had been deposited beforehand. Real-time observation of the SVA process revealed that rodlike single crystals grew with their long axes parallel to the electric field and bridged the prepatterned electrodes. As a result, C8-BTBT crystals automatically formed a field effect transistor (FET) structure and the mobility reached 1.9 cm(2)/(V s). Electric-field-assisted SVA proved a promising method for constructing high-mobility single-crystal FETs at the desired position by a low-cost solution process.

Photodetachment dynamics in a time-dependent oscillating electric field

NASA Astrophysics Data System (ADS)

Wang, De-hua; Xu, Qin-feng; Du, Jie

2017-03-01

Using the time-dependent form of closed orbit theory, as developed by Haggerty and Delos [M.R. Haggerty, J.B. Delos, Phys. Rev. A 61, 053406 (2000)], and by Yang and Robicheaux [B.C. Yang, F. Robicheaux, Phys. Rev. A 93, 053413 (2016)], we study the photodetachment dynamics of a hydrogen negative ion in a time-dependent oscillating electric field. Compared to the photodetachment in a static electric field, the photodetachment dynamics of a negative ion in the time-dependent oscillating electric field become much more complicated but more interesting. Since the applied electric field is oscillating with time, the photodetachment cross section of the negative ion in the oscillating electric field is time-dependent. In a time-dependent framework, we put forward an analytical formula for calculating the instantaneous photodetachment cross section of this system. Our study suggests that the instantaneous photodetachment cross section exhibits oscillatory structure, which depends sensitively on the frequency of the oscillating electric field. With increasing frequency of the oscillating electric field, the number of closed orbits increases and the oscillatory structure in the photodetachment cross section becomes much more complicated. The connection between the detached electron's closed orbit with the oscillating cross section is analyzed quantitatively. This study provides a clear and intuitive picture for the photodetachment processes of a negative ion in the presence of an oscillating electric field. We hope that our work will be useful in guiding future experimental research.

PROGRAM TO DEVELOP ENGINEERING DATA FOR FABRIC FILTRATION WITH INTEGRAL PARTICLE CHARGING AND COLLECTION IN A COMBINED ELECTRIC AND FLOW FIELD

EPA Science Inventory

The paper discusses an EPA program to develop engineering data for the application of electrostatics to fabric filtration in the form of integral particle charging and collection in a combined electric and flow field, which causes particle deposition to be dominated by electrosta...

Assembly of ordered colloidal aggregrates by electric-field-induced fluid flow

PubMed Central

Yeh, Syun-Ru; Seul, Michael; Shraiman, Boris I.

2017-01-01

Suspensions of colloidal particles form a variety of ordered planar structures at an interface in response to an a.c. or d.c. electric field applied normal to the interface1–3. This field-induced pattern formation can be useful, for example, in the processing of materials. Here we explore the origin of the ordering phenomenon. We present evidence suggesting that the long-ranged attraction between particles which causes aggregation is mediated by electric-field-induced fluid flow. We have imaged an axially symmetric flow field around individual particles on a uniform electrode surface. The flow is induced by distortions in the applied electric field owing to inhomogeneities in the ‘double layer’ of ions and counterions at the electrode surface. The beads themselves can create these inhomogeneities, or alternatively, we can modify the electrode surfaces by lithographic patterning so as to introduce specified patterns into the aggregated structures. PMID:28943661

Sound diffraction at wall impedance discontinuities in a circular cylinder - Investigated using Wiener-Hopf technique

NASA Technical Reports Server (NTRS)

Cho, Y.-C.

1983-01-01

The results of ground observations as well as high resolution rocket electric field and particle observations during a breakup event of an intense magnetospheric substorm over northern Scandinavia are discussed. In particular, the characteristics of the substorm-associated electric field, ionospheric currents, and power dissipation during a time period about 15 minutes after substorm onset are addressed. A comparison of the observations with those of a pre-breakup event earlier in the day (Marklund et al., 1982) showed that the ionospheric substorm-related electric field could be split up into two parts: (1) an ambient LT-dependent field, probably of magnetospheric origin; and (2) a small-scale electric field associated with the bright auroral structures, which is superimposed on the LT-dependent field. The consequences for the location of the ionospheric currents and the Joule energy dissipation relative to the auroral forms are discussed. Previously announced in STAR as N83-23117

Monitoring the effects of chelating agents and electrical fields on active forms of Pb and Zn in contaminated soil.

PubMed

Tahmasbian, Iman; Safari Sinegani, Ali Akbar

2013-11-01

The application of electrical fields and chelating agents is an innovative hybrid technology used for the decontamination of soil polluted by heavy metals. The effects of four center-oriented electrical fields and chelating agents on active fractions of lead and zinc were investigated in this pot experiment. Ethylenediaminetetraacetic acid (EDTA) as a synthetic chelator and cow manure extract (CME) and poultry manure extract (PME) as natural chelators were applied to the pots (2 g kg(-1)) 30 days after the first irrigation. Two weeks later, four center-oriented electrical fields were applied in each pot (in three levels of 0, 10, and 30 V) for 1 h each day for 14 days. The soil near the cathode and anodes was collected and analyzed as cathodic and anodic soil, respectively. Results indicated that the soluble-exchangeable fraction of lead and zinc were decreased in the cathodic soil, while the carbonate-bound fractions were increased. In the anodic soil, however, the opposite result was observed. EDTA enhanced the soluble-exchangeable form of the metals in both anodic and cathodic soils. Furthermore, the amounts of carbonate-bound heavy metals were increased by the application of CME in both soils. The organic-bound fraction of the metals was increased by the application of natural chelators, while electrical fields had no significant impacts on this fraction.

Method of using an electric field controlled emulsion phase contactor

DOEpatents

Scott, T.C.

1993-11-16

A system is described for contacting liquid phases comprising a column for transporting a liquid phase contacting system, the column having upper and lower regions. The upper region has a nozzle for introducing a dispersed phase and means for applying thereto a vertically oriented high intensity pulsed electric field. This electric field allows improved flow rates while shattering the dispersed phase into many micro-droplets upon exiting the nozzle to form a dispersion within a continuous phase. The lower region employs means for applying to the dispersed phase a horizontally oriented high intensity pulsed electric field so that the dispersed phase undergoes continuous coalescence and redispersion while being urged from side to side as it progresses through the system, increasing greatly the mass transfer opportunity. 5 figures.

Dependence of the ferroelectric domain shape on the electric field of the microscope tip

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

Starkov, Alexander S.; Starkov, Ivan A., E-mail: starkov@feec.vutbr.cz

2015-08-21

A theory of an equilibrium shape of the domain formed in an electric field of a scanning force microscope (SFM) tip is proposed. We do not assume a priori that the domain has a fixed form. The shape of the domain is defined by the minimum of the free energy of the ferroelectric. This energy includes the energy of the depolarization field, the energy of the domain wall, and the energy of the interaction between the domain and the electric field of the SFM tip. The contributions of the apex and conical part of the tip are examined. Moreover, inmore » the proposed approach, any narrow tip can be considered. The surface energy is determined on the basis of the Ginzburg-Landau-Devonshire theory and takes into account the curvature of the domain wall. The variation of the free energy with respect to the domain shape leads to an integro-differential equation, which must be solved numerically. Model results are illustrated for lithium tantalate ceramics.« less

Tissue interactions with nonionizing electromagnetic fields. Final report, March 1979-February 1986

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

Adey, W.R.; Bawin, S.M.; Byus, C.V.

1986-08-01

This report provides an overview of this research program focused on basic research in nervous system responses to electric fields at 60 Hz. The emphasis in this project was to determine the fundamental mechanisms underlying some phenomena of electric field interactions in neural systems. The five studies of the initial program were tests of behavioral responses in the rat based upon the hypothesis that electric field detection might follow psychophysical rules known from prior research with light, sound and other stimuli; tests of electrophysiological responses to ''normal'' forms of stimulation in rat brain tissue exposed in vitro to electric fields,more » based on the hypothesis that the excitability of brain tissue might be affected by fields in the extracellular environment; tests of electrophysiological responses of spontaneously active pacemaker neurons of the Aplysia abdominal ganglion, based on the hypothesis that electric field interactions at the cell membrane might affect the balance among the several membrane-related processes that govern pacemaker activity; studies of mechanisms of low frequency electromagnetic field interactions with bone cells in the context of field therapy of ununited fractures; and manipulation of cell surface receptor proteins in studies of their mobility during EM field exposure.« less

Ion Velocity Distribution in a Low-Power Cylindrical Hall Thruster

DTIC Science & Technology

2010-07-01

profile inside a CHT – the magnetic field lines are believed to form equipotential surfaces , creating an electric field that has a significant axial...centerline of the channel. The resulting equipotential surfaces provide an electric field profile with a significant outward pointing radial component...pole and creating a region of the channel with a low surface -to-volume area (a cylindrical region), the CHT as developed by Princeton University reduces

A proposed concept for the extraction of energy stored in magnetic or electric fields in space

NASA Technical Reports Server (NTRS)

Papailiou, D. D.

1976-01-01

It is known that enormous energy resources associated with electric, magnetic, gravitational, and other fields exist in space. It is also known that the major difficulty in 'tapping' this energy arises from the extremely low density level at which this energy exists. An analytical study has been made of a particular scheme that appears promising for an efficient utilization of some of these energy resources in propulsion. The principle involves the exchange of energy between a fluctuating magnetic field and a velocity field of electrically conducting fluid in turbulent motion located onboard a spacecraft. Under certain conditions the total energy of the turbulent flow field onboard the spacecraft can be increased and this increase appears in the form of Joulean heat. The utilization of the fluctuating part of the magnetic field, in the form of Joulean dissipation (because of its random character) does not introduce any drag on the spacecraft. The application appears promising for flights in the vicinity of Jupiter and other planets. The rate at which energy is gained by the conducting fluid is of the order of 100 watts when the rms value of the fluctuating magnetic field strength is about 1 gauss.

Molecular-like hierarchical self-assembly of monolayers of mixtures of particles

PubMed Central

Singh, P.; Hossain, M.; Gurupatham, S. K.; Shah, K.; Amah, E.; Ju, D.; Janjua, M.; Nudurupati, S.; Fischer, I.

2014-01-01

We present a technique that uses an externally applied electric field to self-assemble monolayers of mixtures of particles into molecular-like hierarchical arrangements on fluid-liquid interfaces. The arrangements consist of composite particles (analogous to molecules) which are arranged in a pattern. The structure of a composite particle depends on factors such as the relative sizes of the particles and their polarizabilities, and the electric field intensity. If the particles sizes differ by a factor of two or more, the composite particle has a larger particle at its core and several smaller particles form a ring around it. The number of particles in the ring and the spacing between the composite particles depend on their polarizabilities and the electric field intensity. Approximately same sized particles form chains (analogous to polymeric molecules) in which positively and negatively polarized particles alternate. PMID:25510331

Self-assembly of metal nanowires induced by alternating current electric fields

NASA Astrophysics Data System (ADS)

García-Sánchez, Pablo; Arcenegui, Juan J.; Morgan, Hywel; Ramos, Antonio

2015-01-01

We describe the reversible assembly of an aqueous suspension of metal nanowires into two different 2-dimensional stable configurations. The assembly is induced by an AC electric field of magnitude around 10 kV/m. It is known that single metal nanowires orientate parallel to the electric field for all values of applied frequency, according to two different mechanisms depending on the frequency. These different mechanisms also govern the mutual interaction between nanowires, which leads to directed-assembly into distinctive structures, the shape of which depends on the frequency of the applied field. We show that for frequencies higher than the typical frequency for charging the electrical double layer at the metal-electrolyte interface, dipole-dipole interaction leads to the formation of chains of nanowires. For lower frequencies, the nanowires form wavy bands perpendicular to the electric field direction. This behavior appears to be driven by the electroosmotic flow induced on the metal surface of the nanowires. Remarkably, no similar structures have been reported in previous studies of nanowires.

Space-charge-limited currents for cathodes with electric field enhanced geometry

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

Lai, Dingguo, E-mail: laidingguo@nint.ac.cn; Qiu, Mengtong; Xu, Qifu

This paper presents the approximate analytic solutions of current density for annulus and circle cathodes. The current densities of annulus and circle cathodes are derived approximately from first principles, which are in agreement with simulation results. The large scaling laws can predict current densities of high current vacuum diodes including annulus and circle cathodes in practical applications. In order to discuss the relationship between current density and electric field on cathode surface, the existing analytical solutions of currents for concentric cylinder and sphere diodes are fitted from existing solutions relating with electric field enhancement factors. It is found that themore » space-charge-limited current density for the cathode with electric-field enhanced geometry can be written in a general form of J = g(β{sub E}){sup 2}J{sub 0}, where J{sub 0} is the classical (1D) Child-Langmuir current density, β{sub E} is the electric field enhancement factor, and g is the geometrical correction factor depending on the cathode geometry.« less

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

Fukao, Shinji; Nakanishi, Yoshikazu; Mizoguchi, Tadahiro

X-rays are radiated due to the bremsstrahlung caused by the collision of electrons with a metal target placed opposite the negative electric surface of a crystal by changing the temperature of a LiNbO{sub 3} single crystal uniaxially polarized in the c-axis direction. It is suggested that both electric field intensity and electron density determine the intensity of X-ray radiation. Electrons are supplied by the ionization of residual gas in space, field emission from a case inside which a crystal is located, considered to be due to the high electric-field intensity formed by the surface charges on the crystal, and anmore » external electron source, such as a thermionic source. In a high vacuum, it was found that the electrons supplied by electric-field emission mainly contribute to the radiation of X-rays. It was found that the integrated intensity of X-rays can be maximized by supplying electrons both external and by electric-field emission. Furthermore, the integrated intensity of the X-rays is stable for many repeated temperature changes.« less

A combined vector potential-scalar potential method for FE computation of 3D magnetic fields in electrical devices with iron cores

NASA Technical Reports Server (NTRS)

Wang, R.; Demerdash, N. A.

1991-01-01

A method of combined use of magnetic vector potential based finite-element (FE) formulations and magnetic scalar potential (MSP) based formulations for computation of three-dimensional magnetostatic fields is introduced. In this method, the curl-component of the magnetic field intensity is computed by a reduced magnetic vector potential. This field intensity forms the basic of a forcing function for a global magnetic scalar potential solution over the entire volume of the region. This method allows one to include iron portions sandwiched in between conductors within partitioned current-carrying subregions. The method is most suited for large-scale global-type 3-D magnetostatic field computations in electrical devices, and in particular rotating electric machinery.

Performance and Mechanisms of Ultrafiltration Membrane Fouling Mitigation by Coupling Coagulation and Applied Electric Field in a Novel Electrocoagulation Membrane Reactor.

PubMed

Sun, Jingqiu; Hu, Chengzhi; Tong, Tiezheng; Zhao, Kai; Qu, Jiuhui; Liu, Huijuan; Elimelech, Menachem

2017-08-01

A novel electrocoagulation membrane reactor (ECMR) was developed, in which ultrafiltration (UF) membrane modules are placed between electrodes to improve effluent water quality and reduce membrane fouling. Experiments with feedwater containing clays (kaolinite) and natural organic matter (humic acid) revealed that the combined effect of coagulation and electric field mitigated membrane fouling in the ECMR, resulting in higher water flux than the conventional combination of electrocoagulation and UF in separate units (EC-UF). Higher current densities and weakly acidic pH in the EMCR favored faster generation of large flocs and effectively reduced membrane pore blocking. The hydraulic resistance of the formed cake layers on the membrane surface in ECMR was reduced due to an increase in cake layer porosity and polarity, induced by both coagulation and the applied electric field. The formation of a polarized cake layer was controlled by the applied current density and voltage, with cake layers formed under higher electric field strengths showing higher porosity and hydrophilicity. Compared to EC-UF, ECMR has a smaller footprint and could achieve significant energy savings due to improved fouling resistance and a more compact reactor design.

Magnetic and electric field meters developed for the US Department of Energy

NASA Technical Reports Server (NTRS)

Kirkham, H.; Johnson, A.

1988-01-01

This report describes work done at the Jet Propulsion Laboratory for the Office of Energy Storage and Distribution of DOE on the measurement of power line fields. A magnetic field meter is discussed that uses fiber optics to couple a small measuring probe to a remote readout device. The use of fiber optics minimizes electric field perturbation due to the presence of the probe and provides electric isolation for the probe, so that it could be used in a high field or high voltage environment. Power to operate the sensor electronics is transferred via an optical fiber, and converted to electrical form by a small photodiode array. The fundamental, the second and third harmonics of the field are filtered and separately measured, as well as the broadband rms level of the field. The design of the meter is described in detail and data from laboratory tests are presented. The report also describes work done to improve the performance of a DC bushing in a Swedish factory, using the improved meter. The DC electric fields are measured with synchronous detection to provide field magnitude data in two component directions.

Pressure, temperature, and electric field dependence of phase transformations in niobium modified 95/5 lead zirconate titanate

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

Dong, Wen D.; Carlos Valadez, J.; Gallagher, John A.

2015-06-28

Ceramic niobium modified 95/5 lead zirconate-lead titanate (PZT) undergoes a pressure induced ferroelectric to antiferroelectric phase transformation accompanied by an elimination of polarization and a volume reduction. Electric field and temperature drive the reverse transformation from the antiferroelectric to ferroelectric phase. The phase transformation was monitored under pressure, temperature, and electric field loading. Pressures and temperatures were varied in discrete steps from 0 MPa to 500 MPa and 25 °C to 125 °C, respectively. Cyclic bipolar electric fields were applied with peak amplitudes of up to 6 MV m{sup −1} at each pressure and temperature combination. The resulting electric displacement–electric field hysteresis loops weremore » open “D” shaped at low pressure, characteristic of soft ferroelectric PZT. Just below the phase transformation pressure, the hysteresis loops took on an “S” shape, which split into a double hysteresis loop just above the phase transformation pressure. Far above the phase transformation pressure, when the applied electric field is insufficient to drive an antiferroelectric to ferroelectric phase transformation, the hysteresis loops collapse to linear dielectric behavior. Phase stability maps were generated from the experimental data at each of the temperature steps and used to form a three dimensional pressure–temperature–electric field phase diagram.« less

Electric-Field-Induced Alignment of Block Copolymer/Nanoparticle Blends

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

Liedel, Clemens; Schindler, Kerstin; Pavan, Mariela J.

External electric fi elds readily align birefringent block-copolymer mesophases. In this study the effect of gold nanoparticles on the electric-fi eld-induced alignment of a lamellae-forming polystyrene- block -poly(2-vinylpyridine) copolymer is assessed. Nanoparticles are homogeneously dispersed in the styrenic phase and promote the quantitative alignment of lamellar domains by substantially lowering the critical field strength above which alignment proceeds. The results suggest that the electric-fi eldassisted alignment of nanostructured block copolymer/nanoparticle composites may offer a simple way to greatly mitigate structural and orientational defects of such fi lms under benign experimental conditions.

Electrodynamics of ionospheric weather over low latitudes

NASA Astrophysics Data System (ADS)

Abdu, Mangalathayil Ali

2016-12-01

The dynamic state of the ionosphere at low latitudes is largely controlled by electric fields originating from dynamo actions by atmospheric waves propagating from below and the solar wind-magnetosphere interaction from above. These electric fields cause structuring of the ionosphere in wide ranging spatial and temporal scales that impact on space-based communication and navigation systems constituting an important segment of our technology-based day-to-day lives. The largest of the ionosphere structures, the equatorial ionization anomaly, with global maximum of plasma densities can cause propagation delays on the GNSS signals. The sunset electrodynamics is responsible for the generation of plasma bubble wide spectrum irregularities that can cause scintillation or even disruptions of satellite communication/navigation signals. Driven basically by upward propagating tides, these electric fields can suffer significant modulations from perturbation winds due to gravity waves, planetary/Kelvin waves, and non-migrating tides, as recent observational and modeling results have demonstrated. The changing state of the plasma distribution arising from these highly variable electric fields constitutes an important component of the ionospheric weather disturbances. Another, often dominating, component arises from solar disturbances when coronal mass ejection (CME) interaction with the earth's magnetosphere results in energy transport to low latitudes in the form of storm time prompt penetration electric fields and thermospheric disturbance winds. As a result, drastic modifications can occur in the form of layer restructuring (Es-, F3 layers etc.), large total electron content (TEC) enhancements, equatorial ionization anomaly (EIA) latitudinal expansion/contraction, anomalous polarization electric fields/vertical drifts, enhanced growth/suppression of plasma structuring, etc. A brief review of our current understanding of the ionospheric weather variations and the electrodynamic processes underlying them and some outstanding questions will be presented in this paper.

Quantum control via a genetic algorithm of the field ionization pathway of a Rydberg electron

NASA Astrophysics Data System (ADS)

Gregoric, Vincent C.; Kang, Xinyue; Liu, Zhimin Cheryl; Rowley, Zoe A.; Carroll, Thomas J.; Noel, Michael W.

2017-08-01

Quantum control of the pathway along which a Rydberg electron field ionizes is experimentally and computationally demonstrated. Selective field ionization is typically done with a slowly rising electric field pulse. The (1/n*)4 scaling of the classical ionization threshold leads to a rough mapping between arrival time of the electron signal and principal quantum number of the Rydberg electron. This is complicated by the many avoided level crossings that the electron must traverse on the way to ionization, which in general leads to broadening of the time-resolved field ionization signal. In order to control the ionization pathway, thus directing the signal to the desired arrival time, a perturbing electric field produced by an arbitrary wave-form generator is added to a slowly rising electric field. A genetic algorithm evolves the perturbing field in an effort to achieve the target time-resolved field ionization signal.

The electric field structure of auroral arcs as determined from barium plasma injection experiments

NASA Technical Reports Server (NTRS)

Wescott, E. M.

1981-01-01

Barium plasma injection experiments have revealed a number of features of electric fields in and near auroral forms extending from a few hundred to many thousands of km in altitude. There is evidence for V-type potential structures over some auroras, but not in others. For some auroral arcs, large E fields are found at ionospheric altitudes outside the arc but the E field inside the arc is near zero. In a few other auroras, most recently one investigated in an experiment conducted from Poker Flat on March 22, 1980, large, rapidly fluctuating E fields were detected by barium plasma near 600 km altitude. These E fields suggest that the motion of auroral rays can be an effect of low-altitude electric fields, or that V-type potential structures may be found at low altitudes.

COMSOL based Simulation on the Effect of Electric Field changes due to Lightning on Ground

NASA Astrophysics Data System (ADS)

Premlet, B.; Joby, N. E.; Sabu, S.

2017-12-01

The phenomenon of lightning is accompanied by localised changes in atmospheric electric fields. In cloud-to-ground strike locations, changes in atmospheric electric fields can even be observed at the ground a few minutes prior to a strike. A lot of research has been done already on the electrostatic changes prior to lightning in the region above ground. Through this work, we investigate into the effects of lightning electric fields on/under ground with the aid of simulations done in COMSOL Multiphysics. Horizontal and vertical profiles of voltage gradient, electric field, polarisation etc. are investigated. Simulation experiments were conducted using a general model of lightning electric fields formed using data recorded by the Electric Field Mills(EFMs) from three diverse parts of the world- Kennedy Space Centre (KSC),Florida (Using GHRC datasets),Sonnblick Observatory, Austria and National Centre for Earth Science Studies Trivandrum (NCESS),India. COMSOL models of the global electric circuit were developed using Sandstone as the base model for ground. Similar works in literature have only dealt with lightning electric fields above the ground. This work is the first step towards a high-level simulation on the effects of atmospheric electric field on/below ground. The results of this simulation work can aid lightning forecasting and preparedness by opening new doors for voltage based prediction methods at ground. It is also a tool to understand phenomena such as fulgurites, corona effect etc. It also helps in the design of buried cables and improved grounding systems. This work can also be a first step towards understanding localised potential variations at the ground during lightning.

Controlled nanopatterning of a polymerized ionic liquid in a strong electric field

DOE PAGES

Bocharova, Vera; Agapov, Alexander L.; Tselev, Alexander; ...

2014-12-17

Nanolithography has become a driving force in advancements of the modern day's electronics, allowing for miniaturization of devices and a steady increase of the calculation, power, and storage densities. Among various nanofabrication approaches, scanning probe techniques, including atomic force microscopy (AFM), are versatile tools for creating nanoscale patterns utilizing a range of physical stimuli such as force, heat, or electric field confined to the nanoscale. In this study, the potential of using the electric field localized at the apex of an AFM tip to induce and control changes in the mechanical properties of an ion containing polymer—a polymerized ionic liquidmore » (PolyIL)—on a very localized scale is explored. In particular, it is demonstrated that by means of AFM, one can form topographical features on the surface of PolyIL-based thin films with a significantly lower electric potential and power consumption as compared to nonconductive polymer materials. Lastly,, by tuning the applied voltage and ambient air humidity, control over dimensions of the formed structures is reproducibly achieved.« less

AC Electric Field Communication for Human-Area Networking

NASA Astrophysics Data System (ADS)

Kado, Yuichi; Shinagawa, Mitsuru

We have proposed a human-area networking technology that uses the surface of the human body as a data transmission path and uses an AC electric field signal below the resonant frequency of the human body. This technology aims to achieve a “touch and connect” intuitive form of communication by using the electric field signal that propagates along the surface of the human body, while suppressing both the electric field radiating from the human body and mutual interference. To suppress the radiation field, the frequency of the AC signal that excites the transmitter electrode must be lowered, and the sensitivity of the receiver must be raised while reducing transmission power to its minimally required level. We describe how we are developing AC electric field communication technologies to promote the further evolution of a human-area network in support of ubiquitous services, focusing on three main characteristics, enabling-transceiver technique, application-scenario modeling, and communications quality evaluation. Special attention is paid to the relationship between electro-magnetic compatibility evaluation and regulations for extremely low-power radio stations based on Japan's Radio Law.

Electric-field control of spin waves in multiferroic BiFeO3: Theory

NASA Astrophysics Data System (ADS)

de Sousa, Rogério; Rovillain, P.; Gallais, Y.; Sacuto, A.; Méasson, M. A.; Colson, D.; Forget, A.; Bibes, M.; Barthélémy, A.; Cazayous, M.

2011-03-01

Our recent experiment demonstrated gigantic (30%) electric-field tuning of magnon frequencies in multiferroic BiFeO3. We demonstrate that the origin of this effect is related to two linear magnetoelectric interactions that couple the component of electric field perpendicular to the ferroelectric vector to a quadratic form of the Néel vector. We calculate the magnon spectra due to each of these interactions and show that only one of them is consistent with experimental data. At high electric fields, this interaction induces a phase transition to a homogeneous state, and the multi-magnon spectra will fuse into two magnon frequencies. We discuss the possible microscopic mechanisms responsible for this novel interaction and the prospect for applications in magnonics. We acknowledge support from NSERC-Discovery (Canada) and the Agence Nationale pour la Recherche (France).

Geomagnetic responses to the solar wind and the solar activity

NASA Technical Reports Server (NTRS)

Svalgaard, L.

1975-01-01

Following some historical notes, the formation of the magnetosphere and the magnetospheric tail is discussed. The importance of electric fields is stressed and the magnetospheric convection of plasma and magnetic field lines under the influence of large-scale magnetospheric electric fields is outlined. Ionospheric electric fields and currents are intimately related to electric fields and currents in the magnetosphere and the strong coupling between the two regions is discussed. The energy input of the solar wind to the magnetosphere and upper atmosphere is discussed in terms of the reconnection model where interplanetary magnetic field lines merge or connect with the terrestrial field on the sunward side of the magnetosphere. The merged field lines are then stretched behind earth to form the magnetotail so that kinetic energy from the solar wind is converted into magnetic energy in the field lines in the tail. Localized collapses of the crosstail current, which is driven by the large-scale dawn/dusk electric field in the magnetosphere, divert part of this current along geomagnetic field lines to the ionosphere, causing substorms with auroral activity and magnetic disturbances. The collapses also inject plasma into the radiation belts and build up a ring current. Frequent collapses in rapid succession constitute the geomagnetic storm.

Electrically tunable laser based on oblique heliconical cholesteric liquid crystal

PubMed Central

Xiang, Jie; Varanytsia, Andrii; Minkowski, Fred; Paterson, Daniel A.; Storey, John M. D.; Imrie, Corrie T.; Lavrentovich, Oleg D.; Palffy-Muhoray, Peter

2016-01-01

A cholesteric liquid crystal (CLC) formed by chiral molecules represents a self-assembled one-dimensionally periodic helical structure with pitch p in the submicrometer and micrometer range. Because of the spatial periodicity of the dielectric permittivity, a CLC doped with a fluorescent dye and pumped optically is capable of mirrorless lasing. An attractive feature of a CLC laser is that the pitch p and thus the wavelength of lasing λ¯ can be tuned, for example, by chemical composition. However, the most desired mode to tune the laser, by an electric field, has so far been elusive. Here we present the realization of an electrically tunable laser with λ¯ spanning an extraordinarily broad range (>100 nm) of the visible spectrum. The effect is achieved by using an electric-field-induced oblique helicoidal (OH) state in which the molecules form an acute angle with the helicoidal axis rather than align perpendicularly to it as in a field-free CLC. The principal advantage of the electrically controlled CLCOH laser is that the electric field is applied parallel to the helical axis and thus changes the pitch but preserves the single-harmonic structure. The preserved single-harmonic structure ensures efficiency of lasing in the entire tunable range of emission. The broad tuning range of CLCOH lasers, coupled with their microscopic size and narrow line widths, may enable new applications in areas such as diagnostics, sensing, microscopy, displays, and holography. PMID:27807135

Electrically tunable laser based on oblique heliconical cholesteric liquid crystal.

PubMed

Xiang, Jie; Varanytsia, Andrii; Minkowski, Fred; Paterson, Daniel A; Storey, John M D; Imrie, Corrie T; Lavrentovich, Oleg D; Palffy-Muhoray, Peter

2016-11-15

A cholesteric liquid crystal (CLC) formed by chiral molecules represents a self-assembled one-dimensionally periodic helical structure with pitch [Formula: see text] in the submicrometer and micrometer range. Because of the spatial periodicity of the dielectric permittivity, a CLC doped with a fluorescent dye and pumped optically is capable of mirrorless lasing. An attractive feature of a CLC laser is that the pitch [Formula: see text] and thus the wavelength of lasing [Formula: see text] can be tuned, for example, by chemical composition. However, the most desired mode to tune the laser, by an electric field, has so far been elusive. Here we present the realization of an electrically tunable laser with [Formula: see text] spanning an extraordinarily broad range (>100 nm) of the visible spectrum. The effect is achieved by using an electric-field-induced oblique helicoidal (OH) state in which the molecules form an acute angle with the helicoidal axis rather than align perpendicularly to it as in a field-free CLC. The principal advantage of the electrically controlled CLC OH laser is that the electric field is applied parallel to the helical axis and thus changes the pitch but preserves the single-harmonic structure. The preserved single-harmonic structure ensures efficiency of lasing in the entire tunable range of emission. The broad tuning range of CLC OH lasers, coupled with their microscopic size and narrow line widths, may enable new applications in areas such as diagnostics, sensing, microscopy, displays, and holography.

Quantum transport and the Wigner distribution function for Bloch electrons in spatially homogeneous electric and magnetic fields

NASA Astrophysics Data System (ADS)

Iafrate, G. J.; Sokolov, V. N.; Krieger, J. B.

2017-10-01

The theory of Bloch electron dynamics for carriers in homogeneous electric and magnetic fields of arbitrary time dependence is developed in the framework of the Liouville equation. The Wigner distribution function (WDF) is determined from the single-particle density matrix in the ballistic regime, i.e., collision effects are excluded. In the theory, the single-particle transport equation is established with the electric field described in the vector potential gauge, and the magnetic field is treated in the symmetric gauge. No specific assumptions are made concerning the form of the initial distribution in momentum or configuration space. The general approach is to employ the accelerated Bloch state representation (ABR) as a basis so that the dependence upon the electric field, including multiband Zener tunneling, is treated exactly. Further, in the formulation of the WDF, we transform to a new set of variables so that the final WDF is gauge invariant and is expressed explicitly in terms of the position, kinetic momentum, and time. The methodology for developing the WDF is illustrated by deriving the exact WDF equation for free electrons in homogeneous electric and magnetic fields resulting in the same form as given by the collisionless Boltzmann transport equation (BTE). The methodology is then extended to the case of electrons described by an effective Hamiltonian corresponding to an arbitrary energy band function; the exact WDF equation results for the effective Hamiltonian case are shown to approximate the free electron results when taken to second order in the magnetic field. As a corollary, in these cases, it is shown that if the WDF is a wave packet, then the time rate of change of the electron quasimomentum is given by the Lorentz force. In treating the problem of Bloch electrons in a periodic potential in the presence of homogeneous electric and magnetic fields, the methodology for deriving the WDF reveals a multiband character due to the inherent nature of the Bloch states. The K0 representation of the Bloch envelope functions is employed to express the multiband WDF in a useful form. In examining the single-band WDF, it is found that the collisionless WDF equation matches the equivalent BTE to first order in the magnetic field. These results are necessarily extended to second order in the magnetic field by employing a unitary transformation that diagonalizes the Hamiltonian using the ABR to second order. The unitary transformation process includes a discussion of the multiband WDF transport analysis and the identification of the combined Zener-magnetic-field induced tunneling.

[Measurement of the electric field of the heart in a homogeneous volume conductor].

PubMed

Tsukerman, B M; Titomir, L I

1975-01-01

The paper describes a technique and some results of experimental measurements of electrical potentials generated by an isolated dog heart in homogeneous conductor, drawing equipotential maps of the field, and calculating the characteristics of the dipole equivalent generator of the heart. The form of potential distribution on a spherical surface around the heart and its ideal orthogonal vectorcardiograms are discussed.

Slightly uneven electric field trigatron employed in tens of microseconds charging time.

PubMed

Lin, Jiajin; Yang, Jianhua; Zhang, Jiande; Zhang, Huibo; Yang, Xiao

2014-09-01

To solve the issue of operation instability for the trigatron switch in the application of tens of microseconds or even less charging time, a novel trigatron spark gap with slightly uneven electric field was presented. Compared with the conventional trigatron, the novel trigatron was constructed with an obvious field enhancement on the edge of the opposite electrode. The selection of the field enhancement was analyzed based on the theory introduced by Martin. A low voltage trigatron model was constructed and tested on the tens of microseconds charging time platform. The results show that the character of relative range was improved while the trigger character still held a high level. This slightly uneven electric field typed trigatron is willing to be employed in the Tesla transformer - pulse forming line system.

AC-electric field dependent electroformation of giant lipid vesicles.

PubMed

Politano, Timothy J; Froude, Victoria E; Jing, Benxin; Zhu, Yingxi

2010-08-01

Giant vesicles of larger than 5 microm, which have been of intense interest for their potential as drug delivery vehicles and as a model system for cell membranes, can be rapidly formed from a spin-coated lipid thin film under an electric field. In this work, we explore the AC-field dependent electroformation of giant lipid vesicles in aqueous media over a wide range of AC-frequency from 1 Hz to 1 MHz and peak-to-peak field strength from 0.212 V/mm to 40 V/mm between two parallel conducting electrode surfaces. By using fluorescence microscopy, we perform in-situ microscopic observations of the structural evolution of giant vesicles formed from spin-coated lipid films under varied uniform AC-electric fields. The real-time observation of bilayer bulging from the lipid film, vesicle growth and fusing further examine the critical role of AC-induced electroosmotic flow of surrounding fluids for giant vesicle formation. A rich AC-frequency and field strength phase diagram is obtained experimentally to predict the AC-electroformation of giant unilamellar vesicles (GUVs) of l-alpha-phosphatidylcholine, where a weak dependence of vesicle size on AC-frequency is observed at low AC-field voltages, showing decreased vesicle size with a narrowed size distribution with increased AC-frequency. Formation of vesicles was shown to be constrained by an upper field strength of 10 V/mm and an upper AC-frequency of 10 kHz. Within these parameters, giant lipid vesicles were formed predominantly unilamellar and prevalent across the entire electrode surfaces. Copyright 2010 Elsevier B.V. All rights reserved.

Dependence of nuclear quadrupole resonance transitions on the electric field gradient asymmetry parameter for nuclides with half-integer spins

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

Cho, Herman

2016-09-01

Allowed transition energies and eigenstate expansions have been calculated and tabulated in numerical form as functions of the electric field gradient asymmetry parameter for the zero field Hamiltonian of quadrupolar nuclides with I = 3/2, 5/2, 7/2, and 9/2. These results may be used to interpret nuclear quadrupole resonance (NQR) spectra and extract accurate values of the electric field gradient tensors. Applications of NQR methods to studies of electronic structure in heavy element systems are proposed. This material is based upon work supported by the U.S. Department of Energy Office of Science, Office of Basic Energy Sciences, Heavy Element Chemistrymore » program.« less

Synthesis of In2O3 nanowire-decorated Ga2O3 nanobelt heterostructures and their electrical and field-emission properties.

PubMed

Lin, Jing; Huang, Yang; Bando, Yoshio; Tang, Chengchun; Li, Chun; Golberg, Dmitri

2010-04-27

We report on the synthesis of In2O3 nanowire-decorated Ga2O3 nanobelt heterostructures via a simple catalyst-free method. A typical heterostructure, where an In2O3 nanowire forms a sort of a "dorsal fin" on the Ga2O3 nanobelt, exhibits the T-shaped cross-section. The structure, electrical porperties, and field-emission properties of this material are systematically investigated. The heterostructures possess a typical n-type semiconducting behavior with enhanced conductivity. Field-emission measurements show that they have a low turn-on field (approximately 1.31 V/microm) and a high field-enhancement factor (over 4000). The excellent field-emission characteristics are attributed to their special geometry and good electrical properties. The present In2O3-decorated Ga2O3 heterostructures are envisaged to be decent field-emitters useful in advanced electronic and optoelectronic nanodevices.

PLASMA DEVICE

DOEpatents

Baker, W.R.

1961-08-22

A device is described for establishing and maintaining a high-energy, rotational plasma for use as a fast discharge capacitor. A disc-shaped, current- conducting plasma is formed in an axinl magnetic field and a crossed electric field, thereby creating rotational kinetic enengy in the plasma. Such energy stored in the rotation of the plasma disc is substantial and is convertible tc electrical energy by generator action in an output line electrically coupled to the plasma volume. Means are then provided for discharging the electrical energy into an external circuit coupled to the output line to produce a very large pulse having an extremely rapid rise time in the waveform thereof. (AE C)

Introducing time-dependent molecular fields: a new derivation of the wave equations

NASA Astrophysics Data System (ADS)

Baer, Michael

2018-02-01

This article is part of a series of articles trying to establish the concept molecular field. The theory that induced us to introduce this novel concept is based on the Born-Huang expansion as applied to the Schroedinger equation that describes the interaction of a molecular system with an external electric field. Assuming the molecular system is made up of two coupled adiabatic states the theory leads from a single spatial curl equation, two space-time curl equations and one single space-time divergent equation to a pair of decoupled wave equations usually encountered within the theory of fields. In the present study, just like in the previous study [see Baer et al., Mol. Phys. 114, 227 (2016)] the wave equations are derived for an electric field having two features: (a) its intensity is high enough; (b) its duration is short enough. Although not all the findings are new the derivation, in the present case, is new, straightforward, fluent and much friendlier as compared to the previous one and therefore should be presented again. For this situation the study reveals that the just described interaction creates two fields that coexist within a molecule: one is a novel vectorial field formed via the interaction of the electric field with the Born-Huang non-adiabatic coupling terms (NACTs) and the other is an ordinary, scalar, electric field essentially identical to the original electric field. Section 4 devoted to the visualization of the outcomes via two intersecting Jahn-Teller cones which contain NACTs that become singular at the intersection point of these cones. Finally, the fact that eventually we are facing a kind of a cosmic situation may bring us to speculate that singular NACTs are a result of cosmic phenomena. Thus, if indeed this singularity is somehow connected to reality then, like other singularities in physics, it is formed at (or immediately after) the Big Bang and consequently, guarantees the formation of molecules.

In situ emulsification using a non-uniform alternating electric field

NASA Astrophysics Data System (ADS)

Choi, Suhwan; Saveliev, Alexei V.

2014-08-01

We report an electric field based method for in situ emulsification of water droplets immersed in a continuous oil phase. High density water-in-oil emulsions are generated using non-uniform ac electric fields applied between needle and plate electrodes. An initial water droplet is entrained in the area of high electric field near the needle electrode where it is dispersed under the influence of high electric stresses. Breakup mechanisms responsible for a gradual dispersion of the water droplets are investigated. Identified mechanisms involve drop elongation to a cylindrical shape followed by a capillary breakup, ac electrospraying from individual water droplets, and formation and breakup of bead-like structures comprised by the water droplets interconnected by thin water bridges. Water droplets with diameters close to 1 μm and a narrow size distribution are formed at long processing times. The generated emulsion has a well-defined boundary and is confined near the needle electrode in a shape resembling a pendant drop.

Electric-field triggered controlled release of bioactive volatiles from imine-based liquid crystalline phases.

PubMed

Herrmann, Andreas; Giuseppone, Nicolas; Lehn, Jean-Marie

2009-01-01

Application of an electric field to liquid crystalline film forming imines with negative dielectric anisotropy, such as N-(4-methoxybenzylidene)-4-butylaniline (MBBA, 1), results in the expulsion of compounds that do not participate in the formation of the liquid crystalline phase. Furthermore, amines and aromatic aldehydes undergo component exchange with the imine by generating constitutional dynamic libraries. The strength of the electric field and the duration of its application to the liquid crystalline film influence the release rate of the expelled compounds and, at the same time, modulate the equilibration of the dynamic libraries. The controlled release of volatile organic molecules with different chemical functionalities from the film was quantified by dynamic headspace analysis. In all cases, higher headspace concentrations were detected in the presence of an electric field. These results point to the possibility of using imine-based liquid crystalline films to build devices for the controlled release of a broad variety of bioactive volatiles as a direct response to an external electric signal.

Improvement of a device for detection and characterization of certain atmospheric pollutants. Final report. Perfectionnement d'un appareillage de detection et de caracterisation de certains pollutants atmospheriques

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

Tesseyre, Y.

The study allowed development of an original measuring system for mobility, involving simultaneously a repulsive electrical field and a continuous gas flow. It made it possible to define a model to calculate ionic transparency of grates, taking into account electrical fields below and above them, ion mobility, speed of gas flow and geometric transparency. Calculation of the electrical field proceeded in a plane-plane system, taking into account the space load and diffusion; a graphic method was developed to determine the field, thus avoiding numerical integration of the diffusion equation. The tracings of the mobility spectra obtained in different gases mademore » it possible to determine characteristic discrete mobility values comparable to those observed by other more sophisticated systems for measuring mobilities, such as the flight time systems. Detection of pollutants in weak concentration in dry air was shown. However, the presence of water vapor in the air forms agglomerates around the ions formed, reducing resolution of the system and making it less applicable under normal atmospheric conditions.« less

Effect of interphase permittivity on the electric field distribution of epoxy nanocomposites

NASA Astrophysics Data System (ADS)

Pradeep, Lavanya; Nelson, Avinash; Preetha, P.

2018-05-01

Epoxy plays a vital role in high voltage insulation system due to its superior electrical and thermal properties. Literature reports the enhancement in these properties by the addition of nanofillers to epoxy and this enhancement is attributed to the effect of interphase. Characterization of polymer nanocomposites proves the importance of interphase formed between the polymer and nanoparticle in the composite. It was observed that the permittivity of the interphase is having a significant effect on the properties of these materials. In this work, a three dimensional Epoxy nanocomposite with 0.5 vol%, 1 vol% of alumina particles are modeled using unit cell approach in COMSOL Multiphysics. Simulation is done using several existing interphase permittivity models and field distribution is observed. Results shows the noticeable influence of interphase permittivity on the electric field distribution. A good correlation of electric field distribution with the AC breakdown strength is observed.

Tuning the Schottky barrier in the arsenene/graphene van der Waals heterostructures by electric field

NASA Astrophysics Data System (ADS)

Li, Wei; Wang, Tian-Xing; Dai, Xian-Qi; Wang, Xiao-Long; Ma, Ya-Qiang; Chang, Shan-Shan; Tang, Ya-Nan

2017-04-01

Using density functional theory calculations, we investigate the electronic properties of arsenene/graphene van der Waals (vdW) heterostructures by applying external electric field perpendicular to the layers. It is demonstrated that weak vdW interactions dominate between arsenene and graphene with their intrinsic electronic properties preserved. We find that an n-type Schottky contact is formed at the arsenene/graphene interface with a Schottky barrier of 0.54 eV. Moreover, the vertical electric field can not only control the Schottky barrier height but also the Schottky contacts (n-type and p-type) and Ohmic contacts (n-type) at the interface. Tunable p-type doping in graphene is achieved under the negative electric field because electrons can transfer from the Dirac point of graphene to the conduction band of arsenene. The present study would open a new avenue for application of ultrathin arsenene/graphene heterostructures in future nano- and optoelectronics.

Electro-active device using radial electric field piezo-diaphragm for sonic applications

NASA Technical Reports Server (NTRS)

Bryant, Robert G. (Inventor); Fox, Robert L. (Inventor)

2005-01-01

An electro-active transducer for sonic applications includes a ferroelectric material sandwiched by first and second electrode patterns to form a piezo-diaphragm coupled to a mounting frame. When the device is used as a sonic actuator, the first and second electrode patterns are configured to introduce an electric field into the ferroelectric material when voltage is applied to the electrode patterns. When the device is used as a sonic sensor, the first and second electrode patterns are configured to introduce an electric field into the ferroelectric material when the ferroelectric material experiences deflection in a direction substantially perpendicular thereto. In each case, the electrode patterns are designed to cause the electric field to: i) originate at a region of the ferroelectric material between the first and second electrode patterns, and ii) extend radially outward from the region of the ferroelectric material (at which the electric field originates) and substantially parallel to the plane of the ferroelectric material. The mounting frame perimetrically surrounds the peizo-diaphragm and enables attachment of the piezo-diaphragm to a housing.

The Dynamics of Oblate Drop Between Heterogeneous Plates Under Alternating Electric Field. Non-uniform Field

NASA Astrophysics Data System (ADS)

Kashina, M. A.; Alabuzhev, A. A.

2018-02-01

The dynamics of the incompressible fluid drop under the non-uniform electric field are considered. The drop is bounded axially by two parallel solid planes and the case of heterogeneous plates is investigated. The external electric field acts as an external force that causes motion of the contact line. We assume that the electric current is alternative current and the AC filed amplitude is a spatially non-uniform function. In equilibrium, the drop has the form of a circular cylinder. The equilibrium contact angle is 0.5 π. In order to describe this contact line motion the modified Hocking boundary condition is applied: the velocity of the contact line is proportional to the deviation of the contact angle and the speed of the fast relaxation processes, which frequency is proportional to twice the frequency of the electric field. The Hocking parameter depends on the polar angle, i.e. the coefficient of the interaction between the plate and the fluid (the contact line) is a function of the plane coordinates. This function is expanded in a series of the Laplace operator eigenfunctions.

Radiation of X-Rays Using Uniaxially Polarized LiNbO3 Single Crystal

NASA Astrophysics Data System (ADS)

Fukao, Shinji; Nakanishi, Yoshikazu; Mizoguchi, Tadahiro; Ito, Yoshiaki; Nakamura, Toru; Yoshikado, Shinzo

2009-03-01

X-rays are radiated due to the bremsstrahlung caused by the collision of electrons with a metal target placed opposite the negative electric surface of a crystal by changing the temperature of a LiNbO3 single crystal uniaxially polarized in the c-axis direction. It is suggested that both electric field intensity and electron density determine the intensity of X-ray radiation. Electrons are supplied by the ionization of residual gas in space, field emission from a case inside which a crystal is located, considered to be due to the high electric-field intensity formed by the surface charges on the crystal, and an external electron source, such as a thermionic source. In a high vacuum, it was found that the electrons supplied by electric-field emission mainly contribute to the radiation of X-rays. It was found that the integrated intensity of X-rays can be maximized by supplying electrons both external and by electric-field emission. Furthermore, the integrated intensity of the X-rays is stable for many repeated temperature changes.

Power system applications of fiber optic sensors

NASA Technical Reports Server (NTRS)

Johnston, A. R.; Jackson, S. P.; Kirkham, H.; Yeh, C.

1986-01-01

This document is a progress report of work done in 1985 on the Communications and Control for Electric Power Systems Project at the Jet Propulsion Laboratory. These topics are covered: Electric Field Measurement, Fiber Optic Temperature Sensing, and Optical Power transfer. Work was done on the measurement of ac and dc electric fields. A prototype sensor for measuring alternating fields was made using a very simple electroscope approach. An electronic field mill sensor for dc fields was made using a fiber optic readout, so that the entire probe could be operated isolated from ground. There are several instances in which more precise knowledge of the temperature of electrical power apparatus would be useful. This report describes a number of methods whereby the distributed temperature profile can be obtained using a fiber optic sensor. The ability to energize electronics by means of an optical fiber has the advantage that electrical isolation is maintained at low cost. In order to accomplish this, it is necessary to convert the light energy into electrical form by means of photovoltaic cells. JPL has developed an array of PV cells in gallium arsenide specifically for this purpose. This work is described.

Aligned Single Wall Carbon Nanotube Polymer Composites Using an Electric Field

NASA Technical Reports Server (NTRS)

Park, Cheol; Wiklinson, John; Banda, Sumanth; Ounaies, Zoubeida; Wise, Kristopher E.; Sauti, Godfrey; Lillehei, Peter T.; Harrison, Joycelyn S.

2005-01-01

While high shear alignment has been shown to improve the mechanical properties of single wall carbon nanotubes (SWNT)-polymer composites, it is difficult to control and often results in degradation of the electrical and dielectric properties of the composite. Here, we report a novel method to actively align SWNTs in a polymer matrix, which allows for control over the degree of alignment of SWNTs without the side effects of shear alignment. In this process, SWNTs are aligned via field-induced dipolar interactions among the nanotubes under an AC electric field in a liquid matrix followed by immobilization by photopolymerization while maintaining the electric field. Alignment of SWNTs was controlled as a function of magnitude, frequency, and application time of the applied electric field. The degree of SWNT alignment was assessed using optical microscopy and polarized Raman spectroscopy and the morphology of the aligned nanocomposites was investigated by high resolution scanning electron microscopy. The structure of the field induced aligned SWNTs is intrinsically different from that of shear aligned SWNTs. In the present work, SWNTs are not only aligned along the field, but also migrate laterally to form thick, aligned SWNT percolative columns between the electrodes. The actively aligned SWNTs amplify the electrical and dielectric properties in addition to improving the mechanical properties of the composite. All of these properties of the aligned nanocomposites exhibited anisotropic characteristics, which were controllable by tuning the applied field conditions.

Roll to Roll Electric Field "Z" Alignment of Nanoparticles from Polymer Solutions for Manufacturing Multifunctional Capacitor Films.

PubMed

Guo, Yuanhao; Batra, Saurabh; Chen, Yuwei; Wang, Enmin; Cakmak, Miko

2016-07-20

A roll to roll continuous processing method is developed for vertical alignment ("Z" alignment) of barium titanate (BaTiO3) nanoparticle columns in polystyrene (PS)/toluene solutions. This is accomplished by applying an electric field to a two-layer solution film cast on a carrier: one is the top sacrificial layer contacting the electrode and the second is the polymer solution dispersed with BaTiO3 particles. Flexible Teflon coated mesh is utilized as the top electrode that allows the evaporation of solvent through the openings. The kinetics of particle alignment and chain buckling is studied by the custom-built instrument measuring the real time optical light transmission during electric field application and drying steps. The nanoparticles dispersed in the composite bottom layer form chains due to dipole-dipole interaction under an applied electric field. In relatively weak electric fields, the particle chain axis tilts away from electric field direction due to bending caused by the shrinkage of the film during drying. The use of strong electric fields leads to maintenance of alignment of particle chains parallel to the electric field direction overcoming the compression effect. At the end of the process, the surface features of the top porous electrodes are imprinted at the top of the top sacrificial layer. By removing this layer a smooth surface film is obtained. The nanocomposite films with "Z" direction alignment of BaTiO3 particles show substantially increased dielectric permittivity in the thickness direction for enhancing the performance of capacitors.

[Electrical response of inner membrane structures of corynebacteria during electrotransformation].

PubMed

Tiurin, M V; Voroshilova, E B; Rostova, Iu G; Oparina, N Iu; Gusiatiner, M M

1998-01-01

The efficiency of the electrotransformation of intact cells of corynebacteria by a solitary impulse with a complex shape amounted to 10(6) transformants/microgram of plasmid pNV1 DNA at an electric field strength of 14.2 kW/cm; the voltage-current curve of the cell samples was nonlinear. Under these conditions, the structure of the electric current impulse passing intact cells or protoplasts included oscillations characterized by increasing amplitude and a duration of 170 microseconds, which were not detected in the structure of the electric current impulses at field strengths insufficient for obtaining transformants. These changes in the impulse shape suggest the involvement of internal closed membrane structures in the electrical response of cells to the exogenous electric impulse. Most probably, under conditions of electrical treatment optimal for transformation, electropores are formed in the intracellular membranes of corynebacteria.

Electrical Field Guided Electrospray Deposition for Production of Gradient Particle Patterns.

PubMed

Yan, Wei-Cheng; Xie, Jingwei; Wang, Chi-Hwa

2018-06-06

Our previous work demonstrated the uniform particle pattern formation on the substrates using electrical field guided electrospray deposition. In this work, we reported for the first time the fabrication of gradient particle patterns on glass slides using an additional point, line, or bar electrode based on our previous electrospray deposition configuration. We also demonstrated that the polydimethylsiloxane (PDMS) coating could result in the formation of uniform particle patterns instead of gradient particle patterns on glass slides using the same experimental setup. Meanwhile, we investigated the effect of experimental configurations on the gradient particle pattern formation by computational simulation. The simulation results are in line with experimental observations. The formation of gradient particle patterns was ascribed to the gradient of electric field and the corresponding focusing effect. Cell patterns can be formed on the particle patterns deposited on PDMS-coated glass slides. The formed particle patterns hold great promise for high-throughput screening of biomaterial-cell interactions and sensing.

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

Shlapakovski, A. S.; Beilin, L.; Krasik, Ya. E.

Nanosecond-scale evolution of plasma and RF electromagnetic fields during the release of energy from a microwave pulse compressor with a plasma interference switch was investigated numerically using the code MAGIC. The plasma was simulated in the scope of the gas conductivity model in MAGIC. The compressor embodied an S-band cavity and H-plane waveguide tee with a shorted side arm filled with pressurized gas. In a simplified approach, the gas discharge was initiated by setting an external ionization rate in a layer crossing the side arm waveguide in the location of the electric field antinode. It was found that with increasingmore » ionization rate, the microwave energy absorbed by the plasma in the first few nanoseconds increases, but the absorption for the whole duration of energy release, on the contrary, decreases. In a hybrid approach modeling laser ignition of the discharge, seed electrons were set around the electric field antinode. In this case, the plasma extends along the field forming a filament and the plasma density increases up to the level at which the electric field within the plasma decreases due to the skin effect. Then, the avalanche rate decreases but the density still rises until the microwave energy release begins and the electric field becomes insufficient to support the avalanche process. The extraction of the microwave pulse limits its own power by terminating the rise of the plasma density and filament length. For efficient extraction, a sufficiently long filament of dense plasma must have sufficient time to be formed.« less

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.

Knots in electromagnetism

NASA Astrophysics Data System (ADS)

Arrayás, M.; Bouwmeester, D.; Trueba, J. L.

2017-01-01

Maxwell equations in vacuum allow for solutions with a non-trivial topology in the electric and magnetic field line configurations at any given moment in time. One example is a space filling congruence of electric and magnetic field lines forming circles lying on the surfaces of nested tori. In this example the electric, magnetic and Poynting vector fields are orthogonal everywhere. As time evolves the electric and magnetic fields expand and deform without changing the topology and energy, while the Poynting vector structure remains unchanged while propagating with the speed of light. The topology is characterized by the concept of helicity of the field configuration. Helicity is an important fundamental concept and for massless fields it is a conserved quantity under conformal transformations. We will review several methods by which linked and knotted electromagnetic (spin-1) fields can be derived. A first method, introduced by A. Rañada, uses the formulation of the Maxwell equations in terms of differential forms combined with the Hopf map from the three-sphere S3 to the two-sphere S2. A second method is based on spinor and twistor theory developed by R. Penrose in which elementary twistor functions correspond to the family of electromagnetic torus knots. A third method uses the Bateman construction of generating null solutions from complex Euler potentials. And a fourth method uses special conformal transformations, in particular conformal inversion, to generate new linked and knotted field configurations from existing ones. This fourth method is often accompanied by shifting singularities in the field to complex space-time points. Of course the various methods must be closely related to one another although they have been developed largely independently and they suggest different directions in which to expand the study of topologically non-trivial field configurations. It will be shown how the twistor formulation allows for a direct extension to massless fields of other spin values, such as spin-2 fields satisfying the linearized Einstein vacuum equation, and how the formulation by A. Rañada can be extended to fields for which the electric and magnetic fields are not orthogonal everywhere. Underlying the various methods is the fact that electric and magnetic field lines can be described as the level curves of complex functions. Compactification of R3 naturally leads to finite energy solutions because the fields at infinity in all directions should all converge towards zero. An intriguing question that is raised by the finite energy is whether there is a connection to the quantization of the classical electromagnetic field. We will review some issues related to this question. Another interesting question is why the general formulation of topologically non-trivial solutions uses the electric and magnetic fields instead of the electromagnetic vector potentials. This leads to a discussion of the Clebsch representation of the electromagnetic field strength 2-form. Finally, a topic of great interest is the possibility of experimentally generating and investigating linked and knotted field configurations. Since the non-trivial topological field solutions exploit the special conformal symmetry of the underlying vacuum wave-equations it will only be possible to approximate the solutions in an experiment, which necessarily introduces material objects that will break the special conformal symmetry. We will review the research on plasma configurations in which the magnetic field-line configuration approximates plasma torus knots leading to the prediction of topological solitons in plasma.

FAST OPENING SWITCH

DOEpatents

Bender, M.; Bennett, F.K.; Kuckes, A.F.

1963-09-17

A fast-acting electric switch is described for rapidly opening a circuit carrying large amounts of electrical power. A thin, conducting foil bridges a gap in this circuit and means are provided for producing a magnetic field and eddy currents in the foil, whereby the foil is rapidly broken to open the circuit across the gap. Advantageously the foil has a hole forming two narrow portions in the foil and the means producing the magnetic field and eddy currents comprises an annular coil having its annulus coaxial with the hole in the foil and turns adjacent the narrow portions of the foil. An electrical current flows through the coil to produce the magnetic field and eddy currents in the foil. (AEC)

Donor impurity-related photoionization cross section in GaAs cone-like quantum dots under applied electric field

NASA Astrophysics Data System (ADS)

Iqraoun, E.; Sali, A.; Rezzouk, A.; Feddi, E.; Dujardin, F.; Mora-Ramos, M. E.; Duque, C. A.

2017-06-01

The donor impurity-related electron states in GaAs cone-like quantum dots under the influence of an externally applied static electric field are theoretically investigated. Calculations are performed within the effective mass and parabolic band approximations, using the variational procedure to include the electron-impurity correlation effects. The uncorrelated Schrödinger-like electron states are obtained in quasi-analytical form and the entire electron-impurity correlated states are used to calculate the photoionisation cross section. Results for the electron state energies and the photoionisation cross section are reported as functions of the main geometrical parameters of the cone-like structures as well as of the electric field strength.

Boundary-value problem for a counterrotating electrical discharge in an axial magnetic field. [plasma centrifuge for isotope separation

NASA Technical Reports Server (NTRS)

Hong, S. H.; Wilhelm, H. E.

1978-01-01

An electrical discharge between two ring electrodes embedded in the mantle of a cylindrical chamber is considered, in which the plasma in the anode and cathode regions rotates in opposite directions under the influence of an external axial magnetic field. The associated boundary-value problem for the coupled partial differential equations describing the azimuthal velocity and radial current-density fields is solved in closed form. The velocity, current density, induced magnetic induction, and electric fields are presented for typical Hartmann numbers, magnetic Reynolds numbers, and geometry parameters. The discharge is shown to produce anodic and cathodic plasma sections rotating at speeds of the order 1,000,000 cm/sec for conventional magnetic field intensities. Possible application of the magnetoactive discharge as a plasma centrifuge for isotope separation is discussed.

Semiconductor structures having electrically insulating and conducting portions formed from an AlSb-alloy layer

DOEpatents

Spahn, O.B.; Lear, K.L.

1998-03-10

The semiconductor structure comprises a plurality of semiconductor layers formed on a substrate including at least one layer of a III-V compound semiconductor alloy comprising aluminum (Al) and antimony (Sb), with at least a part of the AlSb-alloy layer being chemically converted by an oxidation process to form superposed electrically insulating and electrically conducting portions. The electrically insulating portion formed from the AlSb-alloy layer comprises an oxide of aluminum (e.g., Al{sub 2}O{sub 3}), while the electrically conducting portion comprises Sb. A lateral oxidation process allows formation of the superposed insulating and conducting portions below monocrystalline semiconductor layers for forming many different types of semiconductor structures having particular utility for optoelectronic devices such as light-emitting diodes, edge-emitting lasers, vertical-cavity surface-emitting lasers, photodetectors and optical modulators (waveguide and surface normal), and for electronic devices such as heterojunction bipolar transistors, field-effect transistors and quantum-effect devices. The invention is expected to be particularly useful for forming light-emitting devices for use in the 1.3--1.6 {mu}m wavelength range, with the AlSb-alloy layer acting to define an active region of the device and to effectively channel an electrical current therein for efficient light generation. 10 figs.

Semiconductor structures having electrically insulating and conducting portions formed from an AlSb-alloy layer

DOEpatents

Spahn, Olga B.; Lear, Kevin L.

1998-01-01

A semiconductor structure. The semiconductor structure comprises a plurality of semiconductor layers formed on a substrate including at least one layer of a III-V compound semiconductor alloy comprising aluminum (Al) and antimony (Sb), with at least a part of the AlSb-alloy layer being chemically converted by an oxidation process to form superposed electrically insulating and electrically conducting portions. The electrically insulating portion formed from the AlSb-alloy layer comprises an oxide of aluminum (e.g. Al.sub.2 O.sub.3), while the electrically conducting portion comprises Sb. A lateral oxidation process allows formation of the superposed insulating and conducting portions below monocrystalline semiconductor layers for forming many different types of semiconductor structures having particular utility for optoelectronic devices such as light-emitting diodes, edge-emitting lasers, vertical-cavity surface-emitting lasers, photodetectors and optical modulators (waveguide and surface normal), and for electronic devices such as heterojunction bipolar transistors, field-effect transistors and quantum-effect devices. The invention is expected to be particularly useful for forming light-emitting devices for use in the 1.3-1.6 .mu.m wavelength range, with the AlSb-alloy layer acting to define an active region of the device and to effectively channel an electrical current therein for efficient light generation.

Electrokinetic Aggregation of Colloidal Particles on Electrodes

NASA Astrophysics Data System (ADS)

Anderson, John L.; Solomentsev, Yuri E.; Guelcher, Scott A.

1999-11-01

Colloidal particles deposited on an electrode have been observed to attract each other and form clusters in the presence of an applied electric field. This aggregation is important to the formation of dense monolayer films during electrophoretic depositon processes. Under dc fields two particles attract each other over a length scale comparable to the particle size, and the velocity of approach between two particles is proportional to the applied electric field and the particles' zeta potential. We have developed a theory for particle aggregation based on electroosmotic flow about each deposited particle. Experimental results for the relative motion of two particles are in good quantitative agreement with the theory. Our recent experiments with ac fields also show attraction between particles that is roughly proportional to the rms electric field but inversely proportional to the frequency. We discuss here a model based on electrokinetic processes that can account for some of the observations in ac fields.

Magnetic-field enhancement beyond the skin-depth limit

NASA Astrophysics Data System (ADS)

Shin, Jonghwa; Park, Namkyoo; Fan, Shanhui; Lee, Yong-Hee

2010-02-01

Electric field enhancement has been actively studied recently and many metallic structures that are capable of locally enhancing electric field have been reported. The Babinet's principle can be utilized, especially in the form of Booker's extension, to transform the known electric field enhancing structures into magnetic field enhancing structures. The authors explain this transformation process and discuss the regime in which this principle breaks down. Unless the metals used can be well approximated with a PEC model, the principle's predictions fails to hold true. Authors confirm this aspect using numerical simulations based on realistic material parameters for actual metals. There is large discrepancy especially when the structural dimensions are comparable or less than the skin-depth at the wavelength of interest. An alternative way to achieve magnetic field enhancement is presented and the design of a connected bow-tie structure is proposed as an example. FDTD simulation results confirm the operation of the proposed structure.

Control of the Intrinsic Sensor Response to Volatile Organic Compounds with Fringing Electric Fields.

PubMed

Henning, Alex; Swaminathan, Nandhini; Vaknin, Yonathan; Jurca, Titel; Shimanovich, Klimentiy; Shalev, Gil; Rosenwaks, Yossi

2018-01-26

The ability to control surface-analyte interaction allows tailoring chemical sensor sensitivity to specific target molecules. By adjusting the bias of the shallow p-n junctions in the electrostatically formed nanowire (EFN) chemical sensor, a multiple gate transistor with an exposed top dielectric layer allows tuning of the fringing electric field strength (from 0.5 × 10 7 to 2.5 × 10 7 V/m) above the EFN surface. Herein, we report that the magnitude and distribution of this fringing electric field correlate with the intrinsic sensor response to volatile organic compounds. The local variations of the surface electric field influence the analyte-surface interaction affecting the work function of the sensor surface, assessed by Kelvin probe force microscopy on the nanometer scale. We show that the sensitivity to fixed vapor analyte concentrations can be nullified and even reversed by varying the fringing field strength, and demonstrate selectivity between ethanol and n-butylamine at room temperature using a single transistor without any extrinsic chemical modification of the exposed SiO 2 surface. The results imply an electric-field-controlled analyte reaction with a dielectric surface extremely compelling for sensitivity and selectivity enhancement in chemical sensors.

Thermocouple shield

DOEpatents

Ripley, Edward B [Knoxville, TN

2009-11-24

A thermocouple shield for use in radio frequency fields. In some embodiments the shield includes an electrically conductive tube that houses a standard thermocouple having a thermocouple junction. The electrically conductive tube protects the thermocouple from damage by an RF (including microwave) field and mitigates erroneous temperature readings due to the microwave or RF field. The thermocouple may be surrounded by a ceramic sheath to further protect the thermocouple. The ceramic sheath is generally formed from a material that is transparent to the wavelength of the microwave or RF energy. The microwave transparency property precludes heating of the ceramic sheath due to microwave coupling, which could affect the accuracy of temperature measurements. The ceramic sheath material is typically an electrically insulating material. The electrically insulative properties of the ceramic sheath help avert electrical arcing, which could damage the thermocouple junction. The electrically conductive tube is generally disposed around the thermocouple junction and disposed around at least a portion of the ceramic sheath. The concepts of the thermocouple shield may be incorporated into an integrated shielded thermocouple assembly.

On the importance of body posture and skin modelling with respect to in situ electric field strengths in magnetic field exposure scenarios

NASA Astrophysics Data System (ADS)

Schmid, Gernot; Hirtl, Rene

2016-06-01

The reference levels and maximum permissible exposure values for magnetic fields that are currently used have been derived from basic restrictions under the assumption of upright standing body models in a standard posture, i.e. with arms laterally down and without contact with metallic objects. Moreover, if anatomical modelling of the body was used at all, the skin was represented as a single homogeneous tissue layer. In the present paper we addressed the possible impacts of posture and skin modelling in scenarios of exposure to a 50 Hz uniform magnetic field on the in situ electric field strength in peripheral tissues, which must be limited in order to avoid peripheral nerve stimulation. We considered different body postures including situations where body parts form large induction loops (e.g. clasped hands) with skin-to-skin and skin-to-metal contact spots and compared the results obtained with a homogeneous single-layer skin model to results obtained with a more realistic two-layer skin representation consisting of a low-conductivity stratum corneum layer on top of a combined layer for the cellular epidermis and dermis. Our results clearly indicated that postures with loops formed of body parts may lead to substantially higher maximum values of induced in situ electric field strengths than in the case of standard postures due to a highly concentrated current density and in situ electric field strength in the skin-to-skin and skin-to-metal contact regions. With a homogeneous single-layer skin, as is used for even the most recent anatomical body models in exposure assessment, the in situ electric field strength may exceed the basic restrictions in such situations, even when the reference levels and maximum permissible exposure values are not exceeded. However, when using the more realistic two-layer skin model the obtained in situ electric field strengths were substantially lower and no violations of the basic restrictions occurred, which can be explained by the current-limiting effect of the low-conductivity stratum corneum layer.

Self-consistent evolution of plasma discharge and electromagnetic fields in a microwave pulse compressor

NASA Astrophysics Data System (ADS)

Shlapakovski, A. S.; Beilin, L.; Hadas, Y.; Schamiloglu, E.; Krasik, Ya. E.

2015-07-01

Nanosecond-scale evolution of plasma and RF electromagnetic fields during the release of energy from a microwave pulse compressor with a plasma interference switch was investigated numerically using the code MAGIC. The plasma was simulated in the scope of the gas conductivity model in MAGIC. The compressor embodied an S-band cavity and H-plane waveguide tee with a shorted side arm filled with pressurized gas. In a simplified approach, the gas discharge was initiated by setting an external ionization rate in a layer crossing the side arm waveguide in the location of the electric field antinode. It was found that with increasing ionization rate, the microwave energy absorbed by the plasma in the first few nanoseconds increases, but the absorption for the whole duration of energy release, on the contrary, decreases. In a hybrid approach modeling laser ignition of the discharge, seed electrons were set around the electric field antinode. In this case, the plasma extends along the field forming a filament and the plasma density increases up to the level at which the electric field within the plasma decreases due to the skin effect. Then, the avalanche rate decreases but the density still rises until the microwave energy release begins and the electric field becomes insufficient to support the avalanche process. The extraction of the microwave pulse limits its own power by terminating the rise of the plasma density and filament length. For efficient extraction, a sufficiently long filament of dense plasma must have sufficient time to be formed.

Method for making field-structured memory materials

DOEpatents

Martin, James E.; Anderson, Robert A.; Tigges, Chris P.

2002-01-01

A method of forming a dual-level memory material using field structured materials. The field structured materials are formed from a dispersion of ferromagnetic particles in a polymerizable liquid medium, such as a urethane acrylate-based photopolymer, which are applied as a film to a support and then exposed in selected portions of the film to an applied magnetic or electric field. The field can be applied either uniaxially or biaxially at field strengths up to 150 G or higher to form the field structured materials. After polymerizing the field-structure materials, a magnetic field can be applied to selected portions of the polymerized field-structured material to yield a dual-level memory material on the support, wherein the dual-level memory material supports read-and-write binary data memory and write once, read many memory.

Remote electrical arc suppression by laser filamentation.

PubMed

Schubert, Elise; Mongin, Denis; Kasparian, Jérôme; Wolf, Jean-Pierre

2015-11-02

We investigate the interaction of narrow plasma channels formed in the filamentation of ultrashort laser pulses, with a DC high voltage. The laser filaments prevent electrical arcs by triggering corona that neutralize the high-voltage electrodes. This phenomenon, that relies on the electric field modulation and free electron release around the filament, opens new prospects to lightning and over-voltage mitigation.

Closed-form nonlinear frequency of flexoelectric nanobeams with surface and nonlocal effects under closed circuit electric field

NASA Astrophysics Data System (ADS)

Barati, Mohammad Reza

2018-02-01

Nonlocal and surface effects on nonlinear vibration characteristics of a flexoelectric nanobeams under magnetic field are examined. Eringen’s nonlocal elasticity as well as surface elasticity theories are employed to describe the size-dependency of the flexoelectric nanobeam. Also, flexoelectricity is an important size-dependent phenomena for piezoelectric structures at nanoscale, related to the strain gradient-electric polarization coupling. After the derivation of governing equation via Hamilton’s principle, Galerkin method is employed to satisfy boundary conditions. Also, analytical procedures are implemented to obtain the closed-form nonlinear frequency of flexoelectric nanobeam. It is showed that magnetic field intensity, flexoelectric parameter, nonlocal parameter, elastic foundation and applied voltage on the top surface of the nanobeam have great influences on nonlinear vibration frequency.

Electric-Field-Induced Amplitude Tuning of Ferromagnetic Resonance Peak in Nano-granular Film FeCoB-SiO2/PMN-PT Composites.

PubMed

Luo, Mei; Zhou, Peiheng; Liu, Yunfeng; Wang, Xin; Xie, Jianliang

2016-12-01

One of the challenges in the design of microwave absorbers lies in tunable amplitude of dynamic permeability. In this work, we demonstrate that electric-field-induced magnetoelastic anisotropy in nano-granular film FeCoB-SiO 2 /PMN-PT (011) composites can be used to tune the amplitude of ferromagnetic resonance peak at room temperature. The FeCoB magnetic particles are separated from each other by SiO 2 insulating matrix and present slightly different in-plane anisotropy fields. As a result, multi-resonances appear in the imaginary permeability (μ″) curve and mixed together to form a broadband absorption peak. The amplitude of the resonance peak could be modulated by external electric field from 118 to 266.

Ionizing potential waves and high-voltage breakdown streamers.

NASA Technical Reports Server (NTRS)

Albright, N. W.; Tidman, D. A.

1972-01-01

The structure of ionizing potential waves driven by a strong electric field in a dense gas is discussed. Negative breakdown waves are found to propagate with a velocity proportional to the electric field normal to the wavefront. This causes a curved ionizing potential wavefront to focus down into a filamentary structure, and may provide the reason why breakdown in dense gases propagates in the form of a narrow leader streamer instead of a broad wavefront.

Dead Zone Accretion Flows in Protostellar Disks

NASA Technical Reports Server (NTRS)

Turner, Neal; Sano, T.

2008-01-01

Planets form inside protostellar disks in a dead zone where the electrical resistivity of the gas is too high for magnetic forces to drive turbulence. We show that much of the dead zone nevertheless is active and flows toward the star while smooth, large-scale magnetic fields transfer the orbital angular momentum radially outward. Stellar X-ray and radionuclide ionization sustain a weak coupling of the dead zone gas to the magnetic fields, despite the rapid recombination of free charges on dust grains. Net radial magnetic fields are generated in the magnetorotational turbulence in the electrically conducting top and bottom surface layers of the disk, and reach the midplane by ohmic diffusion. A toroidal component to the fields is produced near the midplane by the orbital shear. The process is similar to the magnetization of the solar tachocline. The result is a laminar, magnetically driven accretion flow in the region where the planets form.

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

Băloi, Mihaela-Andreea, E-mail: mihaela.baloi88@e-uvt.ro; Crucean, Cosmin

The production of fermions in dipolar electric fields on de Sitter universe is studied. The amplitude and probability of pair production are computed using the exact solution of the Dirac equation in de Sitter spacetime. The form of the dipolar fields is established using the conformal invariance of the Maxwell equations. We obtain that the momentum conservation law is broken in the process of pair production in dipolar electric fields. Also we establish that there are nonvanishing probabilities for processes in which the helicity is conserved/nonconserved. The Minkowski limit is recovered when the expansion factor becomes zero.

Method for electrically isolating an electrically conductive member from another such member

DOEpatents

Tsang, K.L.; Chen, Y.

1984-02-09

The invention relates to methods for electrically isolating a first electrically conductive member from another such member by means of an electrically insulating medium. In accordance with the invention, the insulating medium is provided in the form of MgO which contains a dopant selected from lithium, copper, cobalt, sodium, silver, gold and hydrogen. The dopant is present in the MgO in an amount effective to suppress dielectric breakdown of the MgO, even at elevated temperatures and in the presence of electrical fields.

Bardeen regular black hole with an electric source

NASA Astrophysics Data System (ADS)

Rodrigues, Manuel E.; Silva, Marcos V. de S.

2018-06-01

If some energy conditions on the stress-energy tensor are violated, is possible construct regular black holes in General Relativity and in alternative theories of gravity. This type of solution has horizons but does not present singularities. The first regular black hole was presented by Bardeen and can be obtained from Einstein equations in the presence of an electromagnetic field. E. Ayon-Beato and A. Garcia reinterpreted the Bardeen metric as a magnetic solution of General Relativity coupled to a nonlinear electrodynamics. In this work, we show that the Bardeen model may also be interpreted as a solution of Einstein equations in the presence of an electric source, whose electric field does not behave as a Coulomb field. We analyzed the asymptotic forms of the Lagrangian for the electric case and also analyzed the energy conditions.

High pressure xenon ionization detector

DOEpatents

Markey, J.K.

1989-11-14

A method is provided for detecting ionization comprising allowing particles that cause ionization to contact high pressure xenon maintained at or near its critical point and measuring the amount of ionization. An apparatus is provided for detecting ionization, the apparatus comprising a vessel containing a ionizable medium, the vessel having an inlet to allow high pressure ionizable medium to enter the vessel, a means to permit particles that cause ionization of the medium to enter the vessel, an anode, a cathode, a grid and a plurality of annular field shaping rings, the field shaping rings being electrically isolated from one another, the anode, cathode, grid and field shaping rings being electrically isolated from one another in order to form an electric field between the cathode and the anode, the electric field originating at the anode and terminating at the cathode, the grid being disposed between the cathode and the anode, the field shaping rings being disposed between the cathode and the grid, the improvement comprising the medium being xenon and the vessel being maintained at a pressure of 50 to 70 atmospheres and a temperature of 0 to 30 C. 2 figs.

High pressure xenon ionization detector

DOEpatents

Markey, John K.

1989-01-01

A method is provided for detecting ionization comprising allowing particles that cause ionization to contact high pressure xenon maintained at or near its critical point and measuring the amount of ionization. An apparatus is provided for detecting ionization, the apparatus comprising a vessel containing a ionizable medium, the vessel having an inlet to allow high pressure ionizable medium to enter the vessel, a means to permit particles that cause ionization of the medium to enter the vessel, an anode, a cathode, a grid and a plurality of annular field shaping rings, the field shaping rings being electrically isolated from one another, the anode, cathode, grid and field shaping rings being electrically isolated from one another in order to form an electric field between the cathode and the anode, the electric field originating at the anode and terminating at the cathode, the grid being disposed between the cathode and the anode, the field shaping rings being disposed between the cathode and the grid, the improvement comprising the medium being xenon and the vessel being maintained at a pressure of 50 to 70 atmospheres and a temperature of 0.degree. to 30.degree. C.

Electric field mediated breakdown of thin liquid films separating microscopic emulsion droplets

NASA Astrophysics Data System (ADS)

Mostowfi, Farshid; Khristov, Khristo; Czarnecki, Jan; Masliyah, Jacob; Bhattacharjee, Subir

2007-04-01

The authors present a microfluidic technique for electrically induced breakup of thin films formed between microscopic emulsion droplets. The method involves creating a stationary film at the intersection of two microchannels etched onto a glass substrate. After stabilizing the film, a ramped potential is applied across it. The electrical stresses developed at the film interfaces lead to its rupture above a threshold potential. The potential difference at which the film ruptures assesses the film stability. This approach is employed to demonstrate how surfactant (lecithin) adsorption imparts stability to an ultrathin oil film formed between two water droplets.

Electrical structure in two thunderstorm anvil clouds

NASA Technical Reports Server (NTRS)

Marshall, Thomas C.; Rust, W. David; Winn, William P.; Gilbert, Kenneth E.

1989-01-01

Electrical structures in two thunderstorm anvil clouds (or 'anvils'), one in New Mexico, the other in Oklahoma, were investigated, using measurements of electric field by balloon-carried instruments and a one-dimensional model to calculate the time and spatial variations of electrical parameters in the clear air below the anvil. The electric field soundings through the two thunderstorm anvils showed similar charge structures; namely, negatively charged screening layers on the top and the bottom surfaces, a layer of positive charge in the interior, and one or two layers of zero charge. It is suggested that the positive charge originated in the main positive charge region normally found at high altitudes in the core of thunderclouds, and the negatively charged layers probably formed as screening layers, resulting from the discontinuity in the electrical conductivity at the cloud boundaries.

Charged perfect fluid tori in strong central gravitational and dipolar magnetic fields

NASA Astrophysics Data System (ADS)

Kovář, Jiří; Slaný, Petr; Cremaschini, Claudio; Stuchlík, Zdeněk; Karas, Vladimír; Trova, Audrey

2016-06-01

We study electrically charged perfect fluid toroidal structures encircling a spherically symmetric gravitating object with Schwarzschild spacetime geometry and endowed with a dipole magnetic field. The work represents a direct continuation of our previous general-relativistic studies of electrically charged fluid in the approximation of zero conductivity, which formed tori around a Reissner-Nordström black hole or a Schwarzschild black hole equipped with a test electric charge and immersed in an asymptotically uniform magnetic field. After a general introduction of the zero-conductivity charged fluid model, we discuss a variety of possible topologies of the toroidal fluid configurations. Along with the charged equatorial tori forming interesting coupled configurations, we demonstrate the existence of the off-equatorial tori, for which the dipole type of magnetic field seems to be necessary. We focus on orbiting structures with constant specific angular momentum and on those in permanent rigid rotation. We stress that the general analytical treatment developed in our previous works is enriched here by the integrated form of the pressure equations. To put our work into an astrophysical context, we identify the central object with an idealization of a nonrotating magnetic neutron star. Constraining ranges of its parameters and also parameters of the circling fluid, we discuss a possible relevance of the studied toroidal structures, presenting along with their topology also pressure, density, temperature and charge profiles.

Multifluid magnetohydrodynamics of weakly ionized plasmas

NASA Astrophysics Data System (ADS)

Menzel, Raymond

The process of star formation is an integral part of the new field of astrobiology, which studies the origins of life. Since the gas that collapses to form stars and their resulting protoplanetary disks is known to be weakly ionized and contain magnetic fields, star formation is governed by multifluid magnetohydrodynamics. In this thesis we consider two important problems involved in the process of star formation that may have strongly affected the origins of life, with the goal of determining the thermal effects of these flows and modeling the physical conditions of these environments. We first considered the outstanding problem of how primitive bodies, specifically asteroids, were heated in protoplanetary disks early in their lifetime. Reexamining asteroid heating due to the classic unipolar induction heating mechanism described by Sonett et al. (1970), we find that this mechanism contains a subtle conceptual error. As original conceived, heating due to this mechanism is driven by a uniform, supersonic, fully-ionized, magnetized, T Tauri solar wind, which sweeps past an asteroid and causes the asteroid to experience a motional electric field in its rest frame. We point out that this mechanism ignores the interaction between the body surface and the flow, and thus only correctly describes the electric field far away from the asteroid where the plasma streams freely. In a realistic protoplanetary disk environment, we show that the interaction due to friction between the asteroid surface and the flow causes a shear layer to form close to the body, wherein the motional electric field predicted by Sonett et al. decreases and tends to zero at the asteroid surface. We correct this error by using the equations of multifluid magnetohydrodynamics to explicitly treat the shear layer. We calculate the velocity field in the plasma, and the magnetic and electric fields everywhere for two flows over an idealized infinite asteroid with varying magnetic field orientations. We show that the total electric field in the asteroid may either be of comparable strength to the electric field predicted by Sonett et al. or vanish depending on the magnetic field geometry. We include the effects of dust grains in the gas and calculate the heating rates in the plasma flow due to ion-neutral scattering and viscous dissipation. We term this newly discovered heating mechanism "electrodynamic heating", use measurements of asteroid electrical conductivities to estimate the upper limits of the possible heating rates and amount of thermal energy that can be deposited in the solid body, and compare these to the heating produced by the decay of radioactive nuclei like Al26. For the second problem we modeled molecular line emission from time-dependent multifluid MHD shock waves in star-forming regions. By incorporating realistic radiative cooling by CO and H2 into the numerical method developed by Ciolek & Roberge (2013), we present the only current models of truly time-dependent multifluid MHD shock waves in weakly-ionized plasmas. Using the physical conditions determined by our models, we present predictions of molecular emission in the form of excitation diagrams, which can be compared to observations of protostellar outflows in order to trace the physical conditions of these environments. Current work focuses on creating models for varying initial conditions and shock ages, which are and will be the subject of several in progress studies of observed molecular outflows and will provide further insight into the physics and chemistry of these flows.

High sensitivity electric field monitoring system for control of field-induced CD degradation in reticles (EFM)

NASA Astrophysics Data System (ADS)

Sebald, Thomas; Rider, Gavin

2009-04-01

It has recently been reported [1] that production reticles are subject to progressive CD degradation during use and intense study is under way to try and identify the causes of it. One damage mechanism which has already been identified and quantified [2] is electric field induced migration of chrome (EFM). This can be caused by electric fields that are more than 100x weaker than those that cause ESD. Such low level electric fields can be experienced by a reticle during normal handling and processing steps, as well as coming from external sources during transportation and storage. The field strength of concern is lower than most electrostatic field meters are designed to measure and it can be difficult or impossible to measure such fields inside the cramped environment of equipment. To measure this risk a new sensor device ("E-Reticle") has been developed having the same materials of construction and form factor as a standard chrome-on-quartz reticle. It allows the electric field that a reticle would experience during normal use and handling to be measured and recorded. Results from testing of this device in a semiconductor production facility are reported, showing that certain processes like reticle washing are inherently hazardous. It also enables identification of problems with electrostatic protection measures inside equipment, such as unbalanced ionizers or poor load port grounding. The device is shown to be capable of recording electric fields in the reticle handling environment that are below the recommended maximum that is being proposed for the 2009 ITRS guidelines.

Covariant electromagnetic field lines

NASA Astrophysics Data System (ADS)

Hadad, Y.; Cohen, E.; Kaminer, I.; Elitzur, A. C.

2017-08-01

Faraday introduced electric field lines as a powerful tool for understanding the electric force, and these field lines are still used today in classrooms and textbooks teaching the basics of electromagnetism within the electrostatic limit. However, despite attempts at generalizing this concept beyond the electrostatic limit, such a fully relativistic field line theory still appears to be missing. In this work, we propose such a theory and define covariant electromagnetic field lines that naturally extend electric field lines to relativistic systems and general electromagnetic fields. We derive a closed-form formula for the field lines curvature in the vicinity of a charge, and show that it is related to the world line of the charge. This demonstrates how the kinematics of a charge can be derived from the geometry of the electromagnetic field lines. Such a theory may also provide new tools in modeling and analyzing electromagnetic phenomena, and may entail new insights regarding long-standing problems such as radiation-reaction and self-force. In particular, the electromagnetic field lines curvature has the attractive property of being non-singular everywhere, thus eliminating all self-field singularities without using renormalization techniques.

DC conductivity of a suspension of insulating particles with internal rotation

NASA Astrophysics Data System (ADS)

Pannacci, N.; Lemaire, E.; Lobry, L.

2009-04-01

We analyse the consequences of Quincke rotation on the conductivity of a suspension. Quincke rotation refers to the spontaneous rotation of insulating particles dispersed in a slightly conducting liquid and subject to a high DC electric field: above a critical field, each particle rotates continuously around itself with an axis pointing in any direction perpendicular to the DC field. When the suspension is subject to an electric field lower than the threshold one, the presence of insulating particles in the host liquid decreases the bulk conductivity since the particles form obstacles to ion migration. But for electric fields higher than the critical one, the particles rotate and facilitate ion migration: the effective conductivity of the suspension is increased. We provide a theoretical analysis of the impact of Quincke rotation on the apparent conductivity of a suspension and we present experimental results obtained with a suspension of PMMA particles dispersed in weakly conducting liquids.

High-spatial-frequency periodic surface structures on steel substrate induced by subnanosecond laser pulses

NASA Astrophysics Data System (ADS)

Hikage, Haruki; Nosaka, Nami; Matsuo, Shigeki

2017-11-01

By irradiation with 0.5 ns laser pulses at a wavelength λ = 1.064 µm, laser-induced periodic surface structures (LIPSS) were fabricated on a steel substrate. In addition to low-spatial-frequency LIPSS (LSFL), a high-spatial-frequency LIPSS (HSFL) of period Λ ∼ 0.4λ with two-dimensional expansion was formed, although it is generally recognized that HSFL are formed only by ultrafast laser pulses. The wavevector of the observed HSFL was perpendicular to the electric field of the irradiated laser pulse (each ridge/groove of the HSFL was parallel to the electric field). We discuss the relationship between the formation of HSFL and the pulse duration.

Stability of parallel electroosmotic flow subject to an axial modulated electric field

NASA Astrophysics Data System (ADS)

Suresh, Vinod; Homsy, George

2001-11-01

The stability of parallel electroosmotic flow in a micro-channel subjected to an AC electric field is studied. A spatially uniform time harmonic electric field is applied along the length of a two-dimensional micro-channel containing a dilute electrolytic solution, resulting in a time periodic parallel flow. The top and bottom walls of the channel are maintained at constant potential. The base state ion concentrations and double layer potential are determined using the Poisson-Boltzmann equation in the Debye-Hückel approximation. Experiments by other workers (Santiago et. al., unpublished) have shown that such a system can exhibit instabilities that take the form of mixing motion occurring in the bulk flow outside the double layer. It is shown that such instabilities can potentially result from the coupling of disturbances in the ion concentrations or electric potential to the base state velocity or ion concentrations, respectively. The stability boundary of the system is determined using Floquet theory and its dependence on the modulation frequency and amplitude of the axial electric field is studied.

Dynamics Explorer guest investigator

NASA Technical Reports Server (NTRS)

Sojka, Jan J.

1991-01-01

A data base of satellite particle, electric field, image, and plasma data was used to determine correlations between the fields and the particle auroral boundaries. A data base of 8 days of excellent coverage from all instruments was completed. The geomagnetic conditions associated with each of the selected data periods, the number of UV image passes per study day that were obtained, and the total number of UV images for each day are given in tabular form. For each of the days listed in Table 1, both Vector Electric Field Instrument (VEFI) electric potential data and LAPI integrated particle energy fluxes were obtained. On the average, between 8 and 11 passes of useful data per day were obtained. These data are displayed in a format such that either the statistical electric field model potential or the statistical precipitation energy flux could be superimposed. The Heppner and Maynard (1987) and Hardy et al. (1987) models were used for the electric potential and precipitation, respectively. In addition, the auroral image intensity along the Dynamics Explorer-2 satellite pass could be computed and plotted along with the LAPI precipitation data and Hardy et al. (1987) values.

Shaping metallic glasses by electromagnetic pulsing

PubMed Central

Kaltenboeck, Georg; Demetriou, Marios D.; Roberts, Scott; Johnson, William L.

2016-01-01

With damage tolerance rivalling advanced engineering alloys and thermoplastic forming capabilities analogous to conventional plastics, metallic glasses are emerging as a modern engineering material. Here, we take advantage of their unique electrical and rheological properties along with the classic Lorentz force concept to demonstrate that electromagnetic coupling of electric current and a magnetic field can thermoplastically shape a metallic glass without conventional heating sources or applied mechanical forces. Specifically, we identify a process window where application of an electric current pulse in the presence of a normally directed magnetic field can ohmically heat a metallic glass to a softened state, while simultaneously inducing a large enough magnetic body force to plastically shape it. The heating and shaping is performed on millisecond timescales, effectively bypassing crystallization producing fully amorphous-shaped parts. This electromagnetic forming approach lays the groundwork for a versatile, time- and energy-efficient manufacturing platform for ultrastrong metals. PMID:26853460

Control and monitoring method and system for electromagnetic forming process

DOEpatents

Kunerth, Dennis C.; Lassahn, Gordon D.

1990-01-01

A process, system, and improvement for a process for electromagnetic forming of a workpiece in which characteristics of the workpiece such as its geometry, electrical conductivity, quality, and magnetic permeability can be determined by monitoring the current and voltage in the workcoil. In an electromagnet forming process in which a power supply provides current to a workcoil and the electromagnetic field produced by the workcoil acts to form the workpiece, the dynamic interaction of the electromagnetic fields produced by the workcoil with the geometry, electrical conductivity, and magnetic permeability of the workpiece, provides information pertinent to the physical condition of the workpiece that is available for determination of quality and process control. This information can be obtained by deriving in real time the first several time derivatives of the current and voltage in the workcoil. In addition, the process can be extended by injecting test signals into the workcoil during the electromagnetic forming and monitoring the response to the test signals in the workcoil.

Control of wave propagation in a biological excitable medium by an external electric field.

PubMed

Sebestikova, Lenka; Slamova, Elena; Sevcikova, Hana

2005-03-01

We present an experimental evidence of effects of external electric fields (EFs) on the velocity of pulse waves propagating in a biological excitable medium. The excitable medium used is formed by a layer of starving cells of Dictyostelium discoideum through which the waves of increased concentration of cAMP propagate by reaction-diffusion mechanism. External dc EFs of low intensities (up to 5 V/cm) are shown to speed up the propagation of cAMP waves towards the positive electrode and slow it down towards the negative electrode. Electric fields were also found to support an emergence of new centers, emitting cAMP waves, in front of cAMP waves propagating towards the negative electrode.

Polarizing intestinal epithelial cells electrically through Ror2

PubMed Central

Cao, Lin; McCaig, Colin D.; Scott, Roderick H.; Zhao, Siwei; Milne, Gillian; Clevers, Hans; Zhao, Min; Pu, Jin

2014-01-01

ABSTRACT The apicobasal polarity of enterocytes determines where the brush border membrane (apical membrane) will form, but how this apical membrane faces the lumen is not well understood. The electrical signal across the epithelium could serve as a coordinating cue, orienting and polarizing enterocytes. Here, we show that applying a physiological electric field to intestinal epithelial cells, to mimic the natural electric field created by the transepithelial potential difference, polarized phosphorylation of the actin-binding protein ezrin, increased expression of intestinal alkaline phosphatase (ALPI, a differentiation marker) and remodeled the actin cytoskeleton selectively on the cathode side. In addition, an applied electric field also activated ERK1/2 and LKB1 (also known as STK11), key molecules in apical membrane formation. Disruption of the tyrosine protein kinase transmembrane receptor Ror2 suppressed activation of ERK1/2 and LKB1 significantly, and subsequently inhibited apical membrane formation in enterocytes. Our findings indicate that the endogenous electric field created by the transepithelial potential difference might act as an essential coordinating signal for apical membrane formation at a tissue level, through activation of LKB1 mediated by Ror2–ERK signaling. PMID:24928904

Introduction to Electrical Science.

ERIC Educational Resources Information Center

LePage, Wilbur R.; Balabanian, Norman

This text (in mimeographed form) was developed under contract with the United States Office of Education and is intended as material of a first course in the electrical engineering sequence. Introductory concepts such as charge, fields, potential difference, current, and some of the basic physical laws are presented in Chapter I. Subsequent…

Electro-Osmotic Pulse Technology for Control of Water Seepage in Various Civil Works Structures

DTIC Science & Technology

2006-10-01

where: re temperatu constantBoltzman system theof field electric theofstrength ion (negative) positive a of mass charge electric elementary...water molecules, forming acid at the anode surface. This acid , in turn, attacks the mixed metal oxide coating on the anode eroding it, creating

Transfer function of multimode fiber links using an electric field propagation model: Application to Radio over Fibre Systems.

PubMed

Gasulla, I; Capmany, J

2006-10-02

We present a closed-form expression for the evaluation of the transfer function of a multimode fiber (MMF) link based on the electric field propagation model. After validating the result we investigate the potential for broadband transmission in regions far from baseband. We find that MMFs offer the potential for broadband ROF transmission in the microwave and millimetre wave regions in short and middle reach distances.

Improved Diffraction Efficiency of Polarization-Sensitive Azobenzene-Containing Copolymers in an Electric Field

NASA Astrophysics Data System (ADS)

Davidenko, N. A.; Davidenko, I. I.; Mokrinskaya, E. V.; Pavlov, V. A.; Studzinsky, S. L.; Tarasenko, V. V.; Tonkopieva, L. S.; Chuprina, N. G.

2018-03-01

Recording media for polarization holography based on new azobenzene-containing monomers with octylmethacrylate are created. Their electrophysical and information properties are investigated. Improvement of the diffraction efficiency of holograms in these media in an external electric field formed by charging the free surface of the polymer film in a corona discharge is demonstrated. The diffraction efficiency is improved more in the copolymer, in which the azobenzene fragments possess larger dipole moments.

High-Resolution Large-Field-of-View Ultrasound Breast Imager

DTIC Science & Technology

2012-06-01

plane waves all having the same wave vector magnitude 0k but propagating in different directions . This observation forms the mathematical basis of the...origin of the object Fourier space and is oriented opposite the propagation direction of the probing plane wave field. Moreover, the 43 radius of...in water. Each element was electrically tuned to match to the 50-Ohm impedance of an RF Amplifier powered by a 4.0 MHz electrical signal from a

Electrohydrodynamics of a particle-covered drop

NASA Astrophysics Data System (ADS)

Ouriemi, Malika; Vlahovska, Petia

2014-11-01

We study the dynamics of a drop nearly-completely covered with a particle monolayer in a uniform DC electric field. The weakly conducting fluid system consists of a silicon oil drop suspended in castor oil. A broad range of particle sizes, conductivities, and shapes is explored. In weak electric fields, the presence of particles increases drop deformation compared to a particle-free drop and suppresses the electrohydrodynamic flow. Very good agreement is observed between the measured drop deformation and the small deformation theory derived for surfactant-laden drops (Nganguia et al., 2013). In stronger electric fields, where drops are expected to undergo Quincke rotation (Salipante and Vlahovska, 2010), the presence of the particles greatly decreases the threshold for rotation and the stationary tilted drop configuration observed for clean drop is replaced by a spinning drop with either a wobbling inclination or a very low inclination. These behaviors resemble the predicted response of rigid ellipsoids in uniform electric fields. At even stronger electric fields, the particles can form dynamic wings or the drop implodes. The similar behavior of particle-covered and surfactant-laden drops provides new insights into understanding stability of Pickering emulsions. Supported by NSF-CBET 1437545.

Phase boundaries, nucleation rates and speed of crystal growth of the water-to-ice transition under an electric field: a simulation study

NASA Astrophysics Data System (ADS)

Zaragoza, Alberto; Espinosa, Jorge R.; Ramos, Regina; Cobos, José Antonio; Aragones, Juan Luis; Vega, Carlos; Sanz, Eduardo; Ramírez, Jorge; Valeriani, Chantal

2018-05-01

We investigate with computer simulations the effect of applying an electric field on the water-to-ice transition. We use a combination of state-of-the-art simulation techniques to obtain phase boundaries and crystal growth rates (direct coexistence), nucleation rates (seeding) and interfacial free energies (seeding and mold integration). First, we consider ice Ih, the most stable polymorph in the absence of a field. Its normal melting temperature, speed of crystal growth and nucleation rate (for a given supercooling) diminish as the intensity of the field goes up. Then, we study polarised cubic ice, or ice Icf, the most stable solid phase under a strong electric field. Its normal melting point goes up with the field and, for a given supercooling, under the studied field (0.3 V nm‑1) ice Icf nucleates and grows at a similar rate as Ih with no field. The net effect of the field would then be that ice nucleates at warmer temperatures, but in the form of ice Icf. The main conclusion of this work is that reasonable electric fields (not strong enough to break water molecules apart) are not relevant in the context of homogeneous ice nucleation at 1 bar.

Phase boundaries, nucleation rates and speed of crystal growth of the water-to-ice transition under an electric field: a simulation study.

PubMed

Zaragoza, Alberto; Espinosa, Jorge R; Ramos, Regina; Antonio Cobos, José; Luis Aragones, Juan; Vega, Carlos; Sanz, Eduardo; Ramírez, Jorge; Valeriani, Chantal

2018-05-02

We investigate with computer simulations the effect of applying an electric field on the water-to-ice transition. We use a combination of state-of-the-art simulation techniques to obtain phase boundaries and crystal growth rates (direct coexistence), nucleation rates (seeding) and interfacial free energies (seeding and mold integration). First, we consider ice Ih, the most stable polymorph in the absence of a field. Its normal melting temperature, speed of crystal growth and nucleation rate (for a given supercooling) diminish as the intensity of the field goes up. Then, we study polarised cubic ice, or ice Icf, the most stable solid phase under a strong electric field. Its normal melting point goes up with the field and, for a given supercooling, under the studied field (0.3 V nm -1 ) ice Icf nucleates and grows at a similar rate as Ih with no field. The net effect of the field would then be that ice nucleates at warmer temperatures, but in the form of ice Icf. The main conclusion of this work is that reasonable electric fields (not strong enough to break water molecules apart) are not relevant in the context of homogeneous ice nucleation at 1 bar.

Design, Fabrication and Characterization of a MEMS-Based Three-Dimensional Electric Field Sensor with Low Cross-Axis Coupling Interference

PubMed Central

Ling, Biyun; Peng, Chunrong; Ren, Ren; Chu, Zhaozhi; Zhang, Zhouwei; Lei, Hucheng; Xia, Shanhong

2018-01-01

One of the major concerns in the development of three-dimensional (3D) electric field sensors (EFSs) is their susceptibility to cross-axis coupling interference. The output signal for each sensing axis of a 3D EFS is often coupled by electric field components from the two other orthogonal sensing axes. In this paper, a one-dimensional (1D) electric field sensor chip (EFSC) with low cross-axis coupling interference is presented. It is designed to be symmetrical, forming a pair of in-plane symmetrically-located sensing structures. Using a difference circuit, the 1D EFSC is capable of sensing parallel electric fields along symmetrical structures and eliminating cross-axis coupling interference, which is contrast to previously reported 1D EFSCs designed for perpendicular electric field component measurement. Thus, a 3D EFS with low cross-axis coupling interference can be realized using three proposed 1D EFSCs. This 3D EFS has the advantages of low cross-axis coupling interference, small size, and high integration. The testing and calibration systems of the proposed 3D EFS were developed. Experimental results show that in the range of 0–120 kV/m, cross-axis sensitivities are within 5.48%, and the total measurement errors of this 3D EFS are within 6.16%. PMID:29543744

Partially disordered antiferromagnetism and multiferroic behavior in a frustrated Ising system CoCl 2 – 2 SC ( NH 2 ) 2

DOE PAGES

Mun, Eundeok; Weickert, Dagmar Franziska; Kim, Jaewook; ...

2016-03-01

We investigate partially disordered antiferromagnetism in CoCl 2-2SC(NH 2) 2, in which ab-plane hexagonal layers are staggered along the c axis rather than stacked. A robust 1/3 state forms in applied magnetic fields in which the spins are locked, varying as a function of neither temperature nor field. By contrast, in zero field and applied fields at higher temperatures, partial antiferromagnetic order occurs, in which free spins are available to create a Curie-like magnetic susceptibility. We report measurements of the crystallographic structure and the specific heat, magnetization, and electric polarization down to T = 50mK and up to μ0H =more » 60T. The Co 2+ S = 3/2 spins are Ising-like and form distorted hexagonal layers. The Ising energy scale is well separated from the magnetic exchange, and both energy scales are accessible to the measurements, allowing us to cleanly parametrize them. In transverse fields, a quantum Ising phase transition can be observed at 2 T. Lastly, we find that magnetic exchange striction induces changes in the electric polarization up to 3μC/m 2, and single-ion magnetic anisotropy effects induce a much larger electric polarization change of 300μC/m 2.« less

A Novel Acousto-Electric Levitator for Studies of Drop and Particle Clusters and Arrays

NASA Technical Reports Server (NTRS)

Tian, Yuren; Apfel, Robert E.; Zheng, Yibing

1999-01-01

A novel and compact instrumentation for studying the behavior of drop sprays and of clusters of drops now permits fundamental research into the behavior of reacting and non-reacting fluid and solid species. The new capability is made possible by simultaneous acousto-electric levitation and charging of "seed" droplets (10-30 microns in diameter) which come together in 2-D clusters (with up to 300 droplets). These clusters are interesting in their own right because of their crystalline and quasi-crystalline forms, which depend on the acoustic and electric field parameters. By varying the electric and acoustic field intensities, one can cause a cluster of droplets to condense into larger drops (e.g. 50-300 microns) which, because of their charge, form uniformly spaced 2-D arrays of monodispersed drops (e.g. 30-40 array drops in preliminary experiments). One or more layers of these 2-D arrays can form in the acoustic standing wave. Such a configuration permits a wide range of fundamental studies of drop evaporation, combustion, and nucleation. The drops can be single or multicomponent. Therefore, fundamental materials studies can also be performed. Using this same Cluster and Array Generation (CAG) instrumentation, it has been also possible in preliminary experiments to demonstrate the clustering and arraying of solid particles, both coated with an electrically conducting layer and uncoated, and both charged and uncharged.

Channel waveguides in glass via silver-sodium field-assisted ion exchange

NASA Technical Reports Server (NTRS)

Forrest, K.; Pagano, S. J.; Viehmann, W.

1986-01-01

Multimode channel waveguides have been formed in sodium aluminosilicate glass by field-assisted diffusion of Ag(+) ions from vacuum-evaporated Ag films. The two-dimensional refractive index profiles of the waveguides were controlled by varying the diffusion time, the diffusion temperature, and the electric field strength. Estimates of the diffusion rate through a strip aperture were obtained, assuming the electric field was strong 120-240 V/mm. The maximum change in refractive index in the sodium aluminosilicate glasses was estimated near 65 percent of the change in soda-lime silicate glass. The physical properties of the glasses are given in a table.

Convective Flow Induced by Localized Traveling Magnetic Fields

NASA Technical Reports Server (NTRS)

Mazuruk, Konstantin; Rose, M. Franklin (Technical Monitor)

2001-01-01

An axisymmetric traveling magnetic field induces a meridional base flow in a cylindrical zone of an electrically conducting liquid. This remotely induced flow can be conveniently controlled, in magnitude and direction, and can have benefits for crystal growth applications. In particular, it can be used to offset natural convection. For long vertical cylinders, non-uniform and localized in the propagating direction, magnetic fields are required for this purpose. Here we investigate a particular form of this field, namely that induced by a set of a few electric current coils. An order of magnitude reduction of buoyancy convection is theoretically demonstrated for a vertical Bridgman crystal growth configuration.

Structure of Aristotelian electrodynamics

NASA Astrophysics Data System (ADS)

Jacobson, Ted

2015-07-01

Aristotelian electrodynamics (AE) describes the regime of a plasma with a very strong electric field that is not shorted out, with the charge current determined completely by pair production and the balance of the Lorentz 4-force against the curvature radiation reaction. Here it is shown how the principal null directions and associated eigenvalues of the field tensor govern AE, and how force-free electrodynamics arises smoothly from AE when the eigenvalues (and therefore the electric field in some frame) vanish. A criterion for validity of AE and force-free electrodynamics is proposed in terms of a pair of "field curvature scalars" formed from the first derivative of the principal null directions.

Electromagnetic form factors of singly heavy baryons in the self-consistent SU(3) chiral quark-soliton model

NASA Astrophysics Data System (ADS)

Kim, June-Young; Kim, Hyun-Chul

2018-06-01

The self-consistent chiral quark-soliton model is a relativistic pion mean-field approach in the large Nc limit, which describes both light and heavy baryons on an equal footing. In the limit of the infinitely heavy mass of the heavy quark, a heavy baryon can be regarded as Nc-1 valence quarks bound by the pion mean fields, leaving the heavy quark as a color static source. The structure of the heavy baryon in this scheme is mainly governed by the light-quark degrees of freedom. Based on this framework, we evaluate the electromagnetic form factors of the lowest-lying heavy baryons. The rotational 1 /Nc and strange current quark mass corrections in linear order are considered. We discuss the electric charge and magnetic densities of heavy baryons in comparison with those of the nucleons. The results of the electric charge radii of the positive-charged heavy baryons show explicitly that the heavy baryon is a compact object. The electric form factors are presented. The form factor of Σc++ is compared with that from a lattice QCD. We also discuss the results of the magnetic form factors. The magnetic moments of the baryon sextet with spin 1 /2 and the magnetic radii are compared with other works and the lattice data.

Vertical electric field induced suppression of fine structure splitting of excited state excitons in a single GaAs/AlGaAs island quantum dots

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

Ghali, Mohsen; Laboratory of Nanophotonics, Physics Department, Faculty of Science, Kafrelsheikh University, 33516 Kafrelsheikh; Ohno, Yuzo

2015-09-21

We report experimentally on fine structure splitting (FSS) of various excitonic transitions in single GaAs island quantum dots, formed by a monolayer thickness fluctuation in the narrow GaAs/AlGaAs quantum well, and embedded in an n-i-Schottky diode device. By applying a forward vertical electric field (F) between the top metallic contact and the sample substrate, we observed an in-plane polarization rotation of both the ground and the excited state excitons with increasing the electric field. The polarization rotations were accompanied with a strong decrease in the FSS of the ground as well as the excited state excitons with the field, untilmore » the FSS vanished as F approached 30 kV/cm.« less

Pair aligning improved motility of Quincke rollers.

PubMed

Lu, Shi Qing; Zhang, Bing Yue; Zhang, Zhi Chao; Shi, Yan; Zhang, Tian Hui

2018-06-06

Density-dependent speed is studied in a two-dimensional active colloid in which the colloidal particles are propelled by an external electric field via a Quincke rotation. Above the critcal electric field, dense dynamic clusters form spotaneously, in which the particles are highly aligned in velocity and move much faster than isolated units. Detailed observations on pair collision reveal that the alignment of velocity is induced by the long-ranged hydrodynamic interactions and the improvement of speed in the clusters arises from pair aligning in which two particles are closely paired and rotate synchronically. In the aligning state, the short-range in-plane dipole-dipole attraction enhances the rotation torque and gives rises to a larger rolling speed. The pair aligning becomes difficult and unstable at high electric field where the normal dipole-dipole repulsion becomes dominant. As a consequence, the dependence of speed on density becomes weak increasingly upon the increase of the electric field. This result offers an interpretation for the discrepancy between our and previous observations on Quincke rollers.

Thunderstorm Hypothesis Reasoner

NASA Technical Reports Server (NTRS)

Mulvehill, Alice M.

1994-01-01

THOR is a knowledge-based system which incorporates techniques from signal processing, pattern recognition, and artificial intelligence (AI) in order to determine the boundary of small thunderstorms which develop and dissipate over the area encompassed by KSC and the Cape Canaveral Air Force Station. THOR interprets electric field mill data (derived from a network of electric field mills) by using heuristics and algorithms about thunderstorms that have been obtained from several domain specialists. THOR generates two forms of output: contour plots which visually describe the electric field activity over the network and a verbal interpretation of the activity. THOR uses signal processing and pattern recognition to detect signatures associated with noise or thunderstorm behavior in a near real time fashion from over 31 electrical field mills. THOR's AI component generates hypotheses identifying areas which are under a threat from storm activity, such as lightning. THOR runs on a VAX/VMS at the Kennedy Space Center. Its software is a coupling of C and FORTRAN programs, several signal processing packages, and an expert system development shell.

Reversible control of magnetic interactions by electric field in a single-phase material.

PubMed

Ryan, P J; Kim, J-W; Birol, T; Thompson, P; Lee, J-H; Ke, X; Normile, P S; Karapetrova, E; Schiffer, P; Brown, S D; Fennie, C J; Schlom, D G

2013-01-01

Intrinsic magnetoelectric coupling describes the interaction between magnetic and electric polarization through an inherent microscopic mechanism in a single-phase material. This phenomenon has the potential to control the magnetic state of a material with an electric field, an enticing prospect for device engineering. Here, we demonstrate 'giant' magnetoelectric cross-field control in a tetravalent titanate film. In bulk form, EuTiO(3), is antiferromagnetic. However, both anti and ferromagnetic interactions coexist between different nearest europium neighbours. In thin epitaxial films, strain was used to alter the relative strength of the magnetic exchange constants. We not only show that moderate biaxial compression precipitates local magnetic competition, but also demonstrate that the application of an electric field at this strain condition switches the magnetic ground state. Using first-principles density functional theory, we resolve the underlying microscopic mechanism resulting in G-type magnetic order and illustrate how it is responsible for the 'giant' magnetoelectric effect.

MD simulation study of direct permeation of a nanoparticle across the cell membrane under an external electric field.

PubMed

Shimizu, Kenta; Nakamura, Hideya; Watano, Satoru

2016-06-09

Nanoparticles (NPs) have been attracting much attention for biomedical and pharmaceutical applications. In most of the applications, NPs are required to translocate across the cell membrane and to reach the cell cytosol. Experimental studies have reported that by applying an electric field NPs can directly permeate across the cell membrane without the confinement of NPs by endocytic vesicles. However, damage to the cell can often be a concern. Understanding of the mechanism underlying the direct permeation of NPs under an external electric field can greatly contribute to the realization of a technology for the direct delivery of NPs. Here we investigated the permeation of a cationic gold NP across a phospholipid bilayer under an external electric field using a coarse-grained molecular dynamics simulation. When an external electric field that is equal to the membrane breakdown intensity was applied, a typical NP delivery by electroporation was shown: the cationic gold NP directly permeated across a lipid bilayer without membrane wrapping of the NP, while a persistent transmembrane pore was formed. However, when a specific range of the electric field that is lower than the membrane breakdown intensity was applied, a unique permeation pathway was exhibited: the generated transmembrane pore immediately resealed after the direct permeation of NP. Furthermore, we found that the affinity of the NP for the membrane surface is a key for the self-resealing of the pore. Our finding suggests that by applying an electric field in a suitable range NPs can be directly delivered into the cell with less cellular damage.

Analytical and numerical investigations of bubble behavior in electric fields

NASA Astrophysics Data System (ADS)

Vorreiter, Janelle Orae

The behavior of gas bubbles in liquids is important in a wide range of applications. This study is motivated by a desire to understand the motion of bubbles in the absence of gravity, as in many aerospace applications. Phase-change devices, cryogenic tanks and life-support systems are some of the applications where bubbles exist in space environments. One of the main difficulties in employing devices with bubbles in zero gravity environments is the absence of a buoyancy force. The use of an electric field is found to be an effective means of replacing the buoyancy force, improving the control of bubbles in space environments. In this study, analytical and numerical investigations of bubble behavior under the influence of electric fields are performed. The problem is a difficult one in that the physics of the liquid and the electric field need to be considered simultaneously to model the dynamics of the bubble. Simplifications are required to reduce the problem to a tractable form. In this work, for the liquid and the electric field, assumptions are made which reduce the problem to one requiring only the solution of potentials in the domain of interest. Analytical models are developed using a perturbation analysis applicable for small deviations from a spherical shape. Numerical investigations are performed using a boundary integral code. A number of configurations are found to be successful in promoting bubble motion by varying properties of the electric fields. In one configuration, the natural frequencies of a bubble are excited using time-varying electric and pressure fields. The applied electric field is spatially uniform with frequencies corresponding to shape modes of the bubble. The resulting bubble velocity is related to the strength of the electric field as well as the characteristics of the applied fields. In another configuration, static non-uniform fields are used to encourage bubble motion. The resulting motion is related to the degree of non-uniformity of the applied field. Several geometries are investigated to study the relationship between electrode geometry and bubble behavior.

The radial electric field dynamics in the neoclassical plasmas

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

Novakovskii, S.V.; Liu, C.S.; Sagdeev, R.Z.

1997-12-01

A numerical simulation and analytical theory of the radial electric field dynamics in low collisional tokamak plasmas are presented. An initial value code {open_quotes}ELECTRIC{close_quotes} has been developed to solve the ion drift kinetic equation with a full collisional operator in the Hirshman{endash}Sigmar{endash}Clarke form together with the Maxwell equations. Different scenarios of relaxation of the radial electric field toward the steady-state in response to sudden and adiabatic changes of the equilibrium temperature gradient are presented. It is shown, that while the relaxation is usually accompanied by the geodesic acoustic oscillations, during the adiabatic change these oscillations are suppressed and only themore » magnetic pumping remains. Both the collisional damping and the Landau resonance interaction are shown to be important relaxation mechanisms. Scalings of the relaxation rates versus basic plasma parameters are presented. {copyright} {ital 1997 American Institute of Physics.}« less

On the generation of double layers from ion- and electron-acoustic instabilities

NASA Astrophysics Data System (ADS)

Fu, Xiangrong; Cowee, Misa M.; Gary, S. Peter; Winske, Dan

2016-03-01

A plasma double layer (DL) is a nonlinear electrostatic structure that carries a uni-polar electric field parallel to the background magnetic field due to local charge separation. Past studies showed that DLs observed in space plasmas are mostly associated with the ion acoustic instability. Recent Van Allen Probes observations of parallel electric field structures traveling much faster than the ion acoustic speed have motivated a computational study to test the hypothesis that a new type of DLs—electron acoustic DLs—generated from the electron acoustic instability are responsible for these electric fields. Nonlinear particle-in-cell simulations yield negative results, i.e., the hypothetical electron acoustic DLs cannot be formed in a way similar to ion acoustic DLs. Linear theory analysis and the simulations show that the frequencies of electron acoustic waves are too high for ions to respond and maintain charge separation required by DLs. However, our results do show that local density perturbations in a two-electron-component plasma can result in unipolar-like electric field structures that propagate at the electron thermal speed, suggesting another potential explanation for the observations.

Conformation and structural changes of diblock copolymers with octopus-like micelle formation in the presence of external stimuli

NASA Astrophysics Data System (ADS)

Dammertz, K.; Saier, A. M.; Marti, O.; Amirkhani, M.

2014-04-01

External stimuli such as vapours and electric fields can be used to manipulate the formation of AB-diblock copolymers on surfaces. We study the conformational variation of PS-b-PMMA (polystyrene-block-poly(methyl methacrylate)), PS and PMMA adsorbed on mica and their response to saturated water or chloroform atmospheres. Using specimens with only partial polymer coverage, new unanticipated effects were observed. Water vapour, a non-solvent for all three polymers, was found to cause high surface mobility. In contrast, chloroform vapour (a solvent for all three polymers) proved to be less efficient. Furthermore, the influence of an additional applied electric field was investigated. A dc field oriented parallel to the sample surface induces the formation of polymer islands which assemble into wormlike chains. Moreover, PS-b-PMMA forms octopus-like micelles (OLMs) on mica. Under the external stimuli mentioned above, the wormlike formations of OLMs are able to align in the direction of the external electric field. In the absence of an electric field, the OLMs disaggregate and exhibit phase separated structures under chloroform vapour.

Calculation of the radial electric field with RF sheath boundary conditions in divertor geometry

NASA Astrophysics Data System (ADS)

Gui, B.; Xia, T. Y.; Xu, X. Q.; Myra, J. R.; Xiao, X. T.

2018-02-01

The equilibrium electric field that results from an imposed DC bias potential, such as that driven by a radio frequency (RF) sheath, is calculated using a new minimal two-field model in the BOUT++ framework. Biasing, using an RF-modified sheath boundary condition, is applied to an axisymmetric limiter, and a thermal sheath boundary is applied to the divertor plates. The penetration of the bias potential into the plasma is studied with a minimal self-consistent model that includes the physics of vorticity (charge balance), ion polarization currents, force balance with E× B , ion diamagnetic flow (ion pressure gradient) and parallel electron charge loss to the thermal and biased sheaths. It is found that a positive radial electric field forms in the scrape-off layer and it smoothly connects across the separatrix to the force-balanced radial electric field in the closed flux surface region. The results are in qualitative agreement with the experiments. Plasma convection related to the E× B net flow in front of the limiter is also obtained from the calculation.

Spontaneous formation of electric current sheets and the origin of solar flares

NASA Technical Reports Server (NTRS)

Low, B. C.; Wolfson, R.

1988-01-01

It is demonstrated that the continuous boundary motion of a sheared magnetic field in a tenuous plasma with an infinite electrical conductivity can induce the formation of multiple electric current sheets in the interior plasma. In response to specific footpoint displacements, the quadrupolar magnetic field considered is shown to require the formation of multiple electric current sheets as it achieves a force-free state. Some of the current sheets are found to be of finite length, running along separatrix lines of force which separate lobes of magnetic flux. It is suggested that current sheets in the form of infinitely thin magnetic shear layers may be unstable to resistive tearing, a process which may have application to solar flares.

The Generation of Lighting in the Solar Nebula

NASA Technical Reports Server (NTRS)

Cuzzi, Jeffrey; Desch, S. J.; DeVincenzi, Donald (Technical Monitor)

1998-01-01

The process that melted and formed the chondrules, mm-sized glassy beads within meteorites, has not been conclusively identified. Origin by lightning in the solar nebula is consistent with many features of chondrules, but no viable model of lightning has yet been advanced. We present a model demonstrating how lightning could be generated in the solar nebula which differs from previous models in three important aspects. First, we identify a new', powerful charging mechanism that is based on the differences in contact potentials between particles of different composition, a form of triboelectric charging. In the presence of fine silicate grains and fine iron metal grains, large silicate particles (the chondrules) can acquire charges of +10(exp 5) e. Second, we assume that the chondrule precursor particles are selectively concentrated in clumps 1 - 100 km in size by the turbulent concentration mechanism described by Cuzzi et al. (1996). The concentration of these highly charged particles into clumps, in a background of negatively charged metal grains, is what generates the strong electric fields. Third, we make refinements in the estimates of the breakdown electric field and the ionization rate. We calculate that electric fields large enough to trigger breakdown easily could have existed over regions large enough (approx. 100km) to generate very large discharges of electrical energy (approx. 10(exp 16)erg). The discharges would have been sufficiently energetic and frequent to have formed the chondrules. We place constraints on the generation of lightning and conclude that it could not be generated if the abundance of Al-26 in chondrules was as high as the level in the CAls. This conclusion is consistent with isotopic analyses of chondrules. This possibly implies that Al-26 was non-uniformly distributed in the solar nebula or that the chondrules formed several Myr after the CAIs.

The enhancement mechanism of thin plasma layer on antenna radiation

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

Wang, Chunsheng, E-mail: wangcs@hit.edu.cn; Jiang, Binhao; Li, Xueai

A model of plasma-antenna is carried out to study the radiation enhancement mechanism of antenna covered by thin plasma layer. The results show when the radiation intensity achieves maximum, a region of equal electric field is formed due to the reflection of electric field at the interface of plasma and air. The plasma layer acted as an extension of the antenna. Furthermore, the shape of plasma layer is changed to verify the effect of plasma boundary on antenna radiation. The study shows the effect of thin plasma layer on electromagnetic field and provides a type of plasma antenna.

Evaluation of semiconductor devices for Electric and Hybrid Vehicle (EHV) ac-drive applications, volume 2

NASA Technical Reports Server (NTRS)

Lee, F. C.; Chen, D. Y.; Jovanic, M.; Hopkins, D. C.

1985-01-01

Test data of switching times characterization of bipolar transistors, of field effect transistor's switching times on-resistance and characterization, comparative data of field effect transistors, and test data of field effect transistor's parallel operation characterization are given. Data is given in the form of graphs.

Geomagnetic storm effects on the occurrences of ionospheric irregularities over the African equatorial/low-latitude region

NASA Astrophysics Data System (ADS)

Amaechi, P. O.; Oyeyemi, E. O.; Akala, A. O.

2018-04-01

The study investigated the effects of intense geomagnetic storms of 2015 on the occurrences of large scale ionospheric irregularities over the African equatorial/low-latitude region. Four major/intense geomagnetic storms of 2015 were analyzed for this study. These storms occurred on 17th March 2015 (-229 nT), 22nd June 2015 (-204 nT), 7th October 2015 (-124 nT), and 20th December 2015 (-170 nT). Total Electron Content (TEC) data obtained from five African Global Navigation Satellite Systems (GNSS) stations, grouped into eastern and western sectors were used to derive the ionospheric irregularities proxy indices, e.g., rate of change of TEC (ROT), ROT index (ROTI) and ROTI daily average (ROTIAVE). These indices were characterized alongside with the disturbance storm time (Dst), the Y component of the Interplanetary Electric Field (IEFy), polar cap (PC) index and the H component of the Earth's magnetic field from ground-based magnetometers. Irregularities manifested in the form of fluctuations in TEC. Prompt penetration of electric field (PPEF) and disturbance dynamo electric field (DDEF) modulated the behaviour of irregularities during the main and recovery phases of the geomagnetic storms. The effect of electric field over both sectors depends on the local time of southward turning of IMF Bz. Consequently, westward electric field inhibited irregularities during the main phase of March and October 2015 geomagnetic storms, while for the June 2015 storm, eastward electric field triggered weak irregularities over the eastern sector. The effect of electric field on irregularities during December 2015 storm was insignificant. During the recovery phase of the storms, westward DDEF suppressed irregularities.

Substorm Birkeland currents and Cowling channels in the ionosphere

NASA Astrophysics Data System (ADS)

Fujii, R.

2016-12-01

Field-aligned current (FAC) connects electromagnetically the ionosphere with the magnetosphere and plays important roles on dynamics and energetics in the magnetosphere and the ionosphere. In particular, connections between FACs in the ionosphere give important information on various current sources in the magnetosphere and the linkage between them, although the connection between FACs in the ionosphere does not straightforwardly give that in the magnetosphere. FACs in the ionosphere are closed to each other through ionospheric currents determined with the electric field and the Hall and Pedersen conductivities. The electric field and the conductivities are not independently distributed, but rather they are harmonized with each other spatially and temporarily in a physically consistent manner to give a certain FAC. In particular, the divergence of the Hall current due to the inhomogeneity of the Hall conductivity either flows in/out to the magnetosphere as a secondary FAC or accumulates excess charges that produce a secondary electric field. This electric field drives a current circuit connecting the Hall current with the Pedersen current; a Cowling channel current circuit. The FAC (the electric field) we observe is the sum of the primary and secondary FACs (electric fields). The talk will present characteristics of FACs and associated electric field and auroras during substorms, and the ionospheric current closures between the FACs. A statistical study has shown that the majority of region 1 currents are connected to their adjacent region 2 or region 0 currents, indicating the Pedersen current closure rather than the Hall current closure is dominant. On the other hand, the Pedersen currents associated with surge and substorm-related auroras often are connected to the Hall currents, forming a Cowling channel current circuit within the ionosphere.

Etalon (standard) for surface potential distribution produced by electric activity of the heart.

PubMed

Szathmáry, V; Ruttkay-Nedecký, I

1981-01-01

The authors submit etalon (standard) equipotential maps as an aid in the evaluation of maps of surface potential distributions in living subjects. They were obtained by measuring potentials on the surface of an electrolytic tank shaped like the thorax. The individual etalon maps were determined in such a way that the parameters of the physical dipole forming the source of the electric field in the tank corresponded to the mean vectorcardiographic parameters measured in a healthy population sample. The technique also allows a quantitative estimate of the degree of non-dipolarity of the heart as the source of the electric field.

Electrorheological fluids and methods

DOEpatents

Green, Peter F.; McIntyre, Ernest C.

2015-06-02

Electrorheological fluids and methods include changes in liquid-like materials that can flow like milk and subsequently form solid-like structures under applied electric fields; e.g., about 1 kV/mm. Such fluids can be used in various ways as smart suspensions, including uses in automotive, defense, and civil engineering applications. Electrorheological fluids and methods include one or more polar molecule substituted polyhedral silsesquioxanes (e.g., sulfonated polyhedral silsesquioxanes) and one or more oils (e.g., silicone oil), where the fluid can be subjected to an electric field.

Rotating charged black holes accelerated by an electric field

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

Bicak, Jiri; Kofron, David; Max Planck Institute for Gravitational Physics, Albert Einstein Institute, Am Muehlenberg 1, D-14476 Golm

The Ernst method of removing nodal singularities from the charged C-metric representing a uniformly accelerated black hole with mass m, charge q and acceleration A by 'adding' an electric field E is generalized. Utilizing the new form of the C-metric found recently, Ernst's simple 'equilibrium condition' mA=qE valid for small accelerations is generalized for arbitrary A. The nodal singularity is removed also in the case of accelerating and rotating charged black holes, and the corresponding equilibrium condition is determined.

Electrical transport of spin-polarized carriers in disordered ultrathin films.

PubMed

Hernandez, L M; Bhattacharya, A; Parendo, Kevin A; Goldman, A M

2003-09-19

Slow, nonexponential relaxation of electrical transport accompanied by memory effects has been induced in quench-condensed ultrathin amorphous Bi films by the application of a parallel magnetic field. This behavior, which is very similar to space-charge limited current flow, is found in extremely thin films well on the insulating side of the thickness-tuned superconductor-insulator transition. It may be the signature of a collective state that forms when the carriers are spin polarized at low temperatures and in high magnetic fields.

A study of nucleate boiling and critical heat flux with EHD enhancement

NASA Astrophysics Data System (ADS)

Hristov, Y.; Zhao, D.; Kenning, D. B. R.; Sefiane, K.; Karayiannis, T. G.

2009-05-01

The paper describes results from an experimental and theoretical study of the effect of an electric field on nucleate boiling and the critical heat flux (CHF) in pool boiling of R123 at atmospheric pressure on a horizontal wall with a smooth surface. Two designs of electrode (parallel rods and wire mesh) were used. The experimental data exhibit some differences from the data obtained by other researchers in similar experiments on a wall with a different surface finish and with a slightly different design of wire mesh electrode. The hydrodynamic model for EHD enhancement of CHF cannot reconcile the differences. A theoretical model has been developed for the growth of a single vapour bubble on a superheated wall in an electric field, leading to a numerical simulation based on the level-set method. The model includes matching of sub-models for the micro- and macro-regions, conduction in the wall, distortion of the electric field by the bubble, the temperature dependence of electrical properties and free-charge generation. In the present form of the model, some of these effects are realised in an approximate form. The capability to investigate dry-spot formation and wall temperature changes that might lead to CHF has been demonstrated.

Magnetically insulated transmission line oscillator

DOEpatents

Bacon, Larry D.; Ballard, William P.; Clark, M. Collins; Marder, Barry M.

1988-01-01

A magnetically insulated transmission line oscillator employs self-generated magnetic fields to generate microwave energy. An anode of the oscillator includes slow-wave structures which are formed of a plurality of thin conductive vanes defining cavities therebetween, and a gap is formed between the anode and a cathode of the oscillator. In response to a pulsed voltage applied to the anode and cathode, self-generated magnetic fields arfe produced in a cross-field orientation with respect to the orientation of the electric field between the anode and the cathode. The cross-field magnetic fields insulate the flow of electrons in the gap and confine the flow of electrons within the gap.

Magnetically insulated transmission line oscillator

DOEpatents

Bacon, L.D.; Ballard, W.P.; Clark, M.C.; Marder, B.M.

1987-05-19

A magnetically insulated transmission line oscillator employs self-generated magnetic fields to generate microwave energy. An anode of the oscillator includes slow-wave structures which are formed of a plurality of thin conductive vanes defining cavities therebetween, and a gap is formed between the anode and a cathode of the oscillator. In response to a pulsed voltage applied to the anode and cathode, self-generated magnetic fields are produced in a cross-field orientation with respect to the orientation of the electric field between the anode and the cathode. The cross-field magnetic fields insulate the flow of electrons in the gap and confine the flow of electrons within the gap. 11 figs.

Multi-winding homopolar electric machine

DOEpatents

Van Neste, Charles W

2012-10-16

A multi-winding homopolar electric machine and method for converting between mechanical energy and electrical energy. The electric machine includes a shaft defining an axis of rotation, first and second magnets, a shielding portion, and a conductor. First and second magnets are coaxial with the shaft and include a charged pole surface and an oppositely charged pole surface, the charged pole surfaces facing one another to form a repulsive field therebetween. The shield portion extends between the magnets to confine at least a portion of the repulsive field to between the first and second magnets. The conductor extends between first and second end contacts and is toroidally coiled about the first and second magnets and the shield portion to develop a voltage across the first and second end contacts in response to rotation of the electric machine about the axis of rotation.

The effect of electric field geometry on the performance of electromembrane extraction systems: footprints of a third driving force along with migration and diffusion.

PubMed

Moazami, Hamid Reza; Hosseiny Davarani, Saied Saeed; Mohammadi, Jamil; Nojavan, Saeed; Abrari, Masoud

2015-09-03

The distribution of electric field vectors was first calculated for electromembrane extraction (EME) systems in classical and cylindrical electrode geometries. The results showed that supported liquid membrane (SLM) has a general field amplifying effect due to its lower dielectric constant in comparison with aqueous donor/acceptor solutions. The calculated norms of the electric field vector showed that a DC voltage of 50 V can create huge electric field strengths up to 64 kV m(-1) and 111 kV m(-1) in classical and cylindrical geometries respectively. In both cases, the electric field strength reached its peak value on the inner wall of the SLM. In the case of classical geometry, the field strength was a function of the polar position of the SLM whereas the field strength in cylindrical geometry was angularly uniform. In order to investigate the effect of the electrode geometry on the performance of real EME systems, the analysis was carried out in three different geometries including classical, helical and cylindrical arrangements using naproxen and sodium diclofenac as the model analytes. Despite higher field strength and extended cross sectional area, the helical and cylindrical geometries gave lower recoveries with respect to the classical EME. The observed decline of the signal was proved to be against the relations governing migration and diffusion processes, which means that a third driving force is involved in EME. The third driving force is the interaction between the radially inhomogeneous electric field and the analyte in its neutral form. Copyright © 2015 Elsevier B.V. All rights reserved.

Electrically Guided Assembly of Colloidal Particles

NASA Astrophysics Data System (ADS)

Ristenpart, W. D.; Aksay, I. A.; Saville, D. A.

2002-11-01

In earlier work it was shown that the strength and frequency of an applied electric field alters the dynamic arrangement of particles on an electrode. Two-dimensional 'gas,' 'liquid' and 'solid' arrangements were formed, depending on the field strength and frequency. Since the particles are similarly charged, yet migrate over large distances under the influence of steady or oscillatory fields, it is clear that both hydrodynamic and electrical processes are involved. Here we report on an extensive study of electrically induced ordering in a parallel electrode cell. First, we discuss the kinetics of aggregation in a DC field as measured using video microscopy and digital image analysis. Rate constants were determined as a function of applied electric field strength and particle zeta potential. The kinetic parameters are compared to models based on electrohydrodynamic and electroosmotic fluid flow mechanisms Second, using monodisperse micron-sized particles, we examined the average interparticle spacing over a wide range of applied frequencies and field strengths. Variation of these parameters allows formation of closely-spaced arrangements and ordered arrays of widely separated particles. We find that there is a strong dependence on frequency, but there is surprisingly little influence of the electric field strength past a small threshold. Last, we present experiments with binary suspensions of similarly sized particles with negative but unequal surface potentials. A long-range lateral attraction is observed in an AC field. Depending on the frequency, this attractive interaction results in a diverse set of aggregate morphologies, including superstructured hexagonal lattices. These results are discussed in terms of induced dipole-dipole interactions and electrohydrodynamic flow. Finally, we explore the implications for practical applications.

Piezoelectric wave motor

DOEpatents

Yerganian, Simon Scott

2001-07-17

A piezoelectric motor having a stator in which piezoelectric elements are contained in slots formed in the stator transverse to the desired wave motion. When an electric field is imposed on the elements, deformation of the elements imposes a force perpendicular to the sides of the slot, deforming the stator. Appropriate frequency and phase shifting of the electric field will produce a wave in the stator and motion in a rotor. In a preferred aspect, the piezoelectric elements are configured so that deformation of the elements in direction of an imposed electric field, generally referred to as the d.sub.33 direction, is utilized to produce wave motion in the stator. In a further aspect, the elements are compressed into the slots so as to minimize tensile stresses on the elements in use.

Piezoelectric wave motor

DOEpatents

Yerganian, Simon Scott

2003-02-11

A piezoelectric motor having a stator in which piezoelectric elements are contained in slots formed in the stator transverse to the desired wave motion. When an electric field is imposed on the elements, deformation of the elements imposes a force perpendicular to the sides of the slot, deforming the stator. Appropriate frequency and phase-shifting of the electric field will produce a wave in the stator and motion in a rotor. In a preferred aspect, the piezoelectric elements are configured so that deformation of the elements in the direction of an imposed electric field, generally referred to as the d.sub.33 direction, is utilized to produce wave motion in the stator. In a further aspect, the elements are compressed into the slots so as to minimize tensile stresses on the elements in use.

Fractional power-law spatial dispersion in electrodynamics

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

Tarasov, Vasily E., E-mail: tarasov@theory.sinp.msu.ru; Departamento de Análisis Matemático, Universidad de La Laguna, 38271 La Laguna, Tenerife; Trujillo, Juan J., E-mail: jtrujill@ullmat.es

2013-07-15

Electric fields in non-local media with power-law spatial dispersion are discussed. Equations involving a fractional Laplacian in the Riesz form that describe the electric fields in such non-local media are studied. The generalizations of Coulomb’s law and Debye’s screening for power-law non-local media are characterized. We consider simple models with anomalous behavior of plasma-like media with power-law spatial dispersions. The suggested fractional differential models for these plasma-like media are discussed to describe non-local properties of power-law type. -- Highlights: •Plasma-like non-local media with power-law spatial dispersion. •Fractional differential equations for electric fields in the media. •The generalizations of Coulomb’s lawmore » and Debye’s screening for the media.« less

Dielectric aggregation kinetics of cells in a uniform AC electric field.

PubMed

Tada, Shigeru; Natsuya, Tomoyuki; Tsukamoto, Akira

2014-01-01

Cell manipulation and separation technologies have potential biological and medical applications, including advanced clinical protocols such as tissue engineering. An aggregation model was developed for a human carcinoma (HeLa) cell suspension exposed to a uniform AC electric field, in order to explore the field-induced structure formation and kinetics of cell aggregates. The momentum equations of cells under the action of the dipole-dipole interaction were solved theoretically and the total time required to form linear string-like cluster was derived. The results were compared with those of a numerical simulation. Experiments using HeLa cells were also performed for comparison. The total time required to form linear string-like clusters was derived from a simple theoretical model of the cell cluster kinetics. The growth rates of the average string length of cell aggregates showed good agreement with those of the numerical simulation. In the experiment, cells were found to form massive clusters on the bottom of a chamber. The results imply that the string-like cluster grows rapidly by longitudinal attraction when the electric field is first applied and that this process slows at later times and is replaced by lateral coagulation of short strings. The findings presented here are expected to enable design of methods for the organization of three-dimensional (3D) cellular structures without the use of micro-fabricated substrates, such as 3D biopolymer scaffolds, to manipulate cells into spatial arrangement.

Dependence of Interaction Free Energy between Solutes on an External Electrostatic Field

PubMed Central

Yang, Pei-Kun

2013-01-01

To explore the athermal effect of an external electrostatic field on the stabilities of protein conformations and the binding affinities of protein-protein/ligand interactions, the dependences of the polar and hydrophobic interactions on the external electrostatic field, −Eext, were studied using molecular dynamics (MD) simulations. By decomposing Eext into, along, and perpendicular to the direction formed by the two solutes, the effect of Eext on the interactions between these two solutes can be estimated based on the effects from these two components. Eext was applied along the direction of the electric dipole formed by two solutes with opposite charges. The attractive interaction free energy between these two solutes decreased for solutes treated as point charges. In contrast, the attractive interaction free energy between these two solutes increased, as observed by MD simulations, for Eext = 40 or 60 MV/cm. Eext was applied perpendicular to the direction of the electric dipole formed by these two solutes. The attractive interaction free energy was increased for Eext = 100 MV/cm as a result of dielectric saturation. The force on the solutes along the direction of Eext computed from MD simulations was greater than that estimated from a continuum solvent in which the solutes were treated as point charges. To explore the hydrophobic interactions, Eext was applied to a water cluster containing two neutral solutes. The repulsive force between these solutes was decreased/increased for Eext along/perpendicular to the direction of the electric dipole formed by these two solutes. PMID:23852018

Electrical Characteristics of Organic Field Effect Transistor Formed by Gas Treatment of High-k Al2O3 at Low Temperature

NASA Astrophysics Data System (ADS)

Lee, Sunwoo; Yoon, Seungki; Park, In-Sung; Ahn, Jinho

2009-04-01

We studied the electrical characteristics of an organic field effect transistor (OFET) formed by the hydrogen (H2) and nitrogen (N2) mixed gas treatment of a gate dielectric layer. We also investigated how device mobility is related to the length and width variations of the channel. Aluminum oxide (Al2O3) was used as the gate dielectric layer. After the treatment, the mobility and subthreshold swing were observed to be significantly improved by the decreased hole carrier localization at the interfacial layer between the gate oxide and pentacene channel layers. H2 gas plays an important role in removing the defects of the gate oxide layer at temperatures below 100 °C.

Effect of electrical energy on the efficacy of biofilm treatment using the bioelectric effect

PubMed Central

Kim, Young Wook; Subramanian, Sowmya; Gerasopoulos, Konstantinos; Ben-Yoav, Hadar; Wu, Hsuan-Chen; Quan, David; Carter, Karen; Meyer, Mariana T; Bentley, William E; Ghodssi, Reza

2015-01-01

Background/Objectives: The use of electric fields in combination with small doses of antibiotics for enhanced treatment of biofilms is termed the ‘bioelectric effect’ (BE). Different mechanisms of action for the AC and DC fields have been reported in the literature over the last two decades. In this work, we conduct the first study on the correlation between the electrical energy and the treatment efficacy of the bioelectric effect on Escherichia coli K-12 W3110 biofilms. Methods: A thorough study was performed through the application of alternating (AC), direct (DC) and superimposed (SP) potentials of different amplitudes on mature E. coli biofilms. The electric fields were applied in combination with the antibiotic gentamicin (10 μg/ml) over a course of 24 h, after the biofilms had matured for 24 h. The biofilms were analysed using the crystal violet assay, the colony-forming unit method and fluorescence microscopy. Results: Results show that there is no statistical difference in treatment efficacy between the DC-, AC- and SP-based BE treatment of equivalent energies (analysis of variance (ANOVA) P>0.05) for voltages <1 V. We also demonstrate that the efficacy of the BE treatment as measured by the crystal violet staining method and colony-forming unit assay is proportional to the electrical energy applied (ANOVA P<0.05). We further verify that the treatment efficacy varies linearly with the energy of the BE treatment (r2 =0.984). Our results thus suggest that the energy of the electrical signal is the primary factor in determining the efficacy of the BE treatment, at potentials less than the media electrolysis voltage. Conclusions: Our results demonstrate that the energy of the electrical signal, and not the type of electrical signal (AC or DC or SP), is the key to determine the efficacy of the BE treatment. We anticipate that this observation will pave the way for further understanding of the mechanism of action of the BE treatment method and may open new doors to the use of electric fields in the treatment of bacterial biofilms. PMID:28721233

En route to surface-bound electric field-driven molecular motors.

PubMed

Jian, Huahua; Tour, James M

2003-06-27

Four caltrop-shaped molecules that might be useful as surface-bound electric field-driven molecular motors have been synthesized. The caltrops are comprised of a pair of electron donor-acceptor arms and a tripod base. The molecular arms are based on a carbazole or oligo(phenylene ethynylene) core with a strong net dipole. The tripod base uses a silicon atom as its core. The legs of the tripod bear sulfur-tipped bonding units, as acetyl-protected benzylic thiols, for bonding to a gold surface. The geometry of the tripod base allows the caltrop to project upward from a metallic surface after self-assembly. Ellipsometric studies show that self-assembled monolayers of the caltrops are formed on Au surfaces with molecular thicknesses consistent with the desired upright-shaft arrangement. As a result, the zwitterionic molecular arms might be controllable when electric fields are applied around the caltrops, thereby constituting field-driven motors.

Droplet manipulation by an external electric field for crystalline film growth.

PubMed

Komino, Takeshi; Kuwabara, Hirokazu; Ikeda, Masaaki; Yahiro, Masayuki; Takimiya, Kazuo; Adachi, Chihaya

2013-07-30

Combining droplet manipulation by the application of an electric field with inkjet printing is proposed as a unique technique to control the surface wettability of substrates for solution-processed organic field-effect transistors (FETs). With the use of this technique, uniform thin films of 2,7-dioctyl[1]benzothieno[2,3,-b][1]benzothiopene (C8-BTBT) could be fabricated on the channels of FET substrates without self-assembled monolayer treatment. High-speed camera observation revealed that the crystals formed at the solid/liquid interface. The coverage of the crystals on the channels depended on the ac frequency of the external electric field applied during film formation, leading to a wide variation in the carrier transport of the films. The highest hole mobility of 0.03 cm(2) V(-1) s(-1) was obtained when the coverage was maximized with an ac frequency of 1 kHz.

Tikekar superdense stars in electric fields

NASA Astrophysics Data System (ADS)

Komathiraj, K.; Maharaj, S. D.

2007-04-01

We present exact solutions to the Einstein-Maxwell system of equations with a specified form of the electric field intensity by assuming that the hypersurface {t=constant} are spheroidal. The solution of the Einstein-Maxwell system is reduced to a recurrence relation with variable rational coefficients which can be solved in general using mathematical induction. New classes of solutions of linearly independent functions are obtained by restricting the spheroidal parameter K and the electric field intensity parameter α. Consequently, it is possible to find exact solutions in terms of elementary functions, namely, polynomials and algebraic functions. Our result contains models found previously including the superdense Tikekar neutron star model [J. Math. Phys. 31, 2454 (1990)] when K=-7 and α=0. Our class of charged spheroidal models generalize the uncharged isotropic Maharaj and Leach solutions [J. Math. Phys. 37, 430 (1996)]. In particular, we find an explicit relationship directly relating the spheroidal parameter K to the electromagnetic field.

Finite element method (FEM) model of the mechanical stress on phospholipid membranes from shock waves produced in nanosecond electric pulses (nsEP)

NASA Astrophysics Data System (ADS)

Barnes, Ronald; Roth, Caleb C.; Shadaram, Mehdi; Beier, Hope; Ibey, Bennett L.

2015-03-01

The underlying mechanism(s) responsible for nanoporation of phospholipid membranes by nanosecond pulsed electric fields (nsEP) remains unknown. The passage of a high electric field through a conductive medium creates two primary contributing factors that may induce poration: the electric field interaction at the membrane and the shockwave produced from electrostriction of a polar submersion medium exposed to an electric field. Previous work has focused on the electric field interaction at the cell membrane, through such models as the transport lattice method. Our objective is to model the shock wave cell membrane interaction induced from the density perturbation formed at the rising edge of a high voltage pulse in a polar liquid resulting in a shock wave propagating away from the electrode toward the cell membrane. Utilizing previous data from cell membrane mechanical parameters, and nsEP generated shockwave parameters, an acoustic shock wave model based on the Helmholtz equation for sound pressure was developed and coupled to a cell membrane model with finite-element modeling in COMSOL. The acoustic structure interaction model was developed to illustrate the harmonic membrane displacements and stresses resulting from shockwave and membrane interaction based on Hooke's law. Poration is predicted by utilizing membrane mechanical breakdown parameters including cortical stress limits and hydrostatic pressure gradients.

Optically initiated silicon carbide high voltage switch

DOEpatents

Caporaso, George J [Livermore, CA; Sampayan, Stephen E [Manteca, CA; Sullivan, James S [Livermore, CA; Sanders,; David, M [Livermore, CA

2011-02-22

An improved photoconductive switch having a SiC or other wide band gap substrate material, such as GaAs and field-grading liners composed of preferably SiN formed on the substrate adjacent the electrode perimeters or adjacent the substrate perimeters for grading the electric fields.

Absolute and convective instabilities of a film flow down a vertical fiber subjected to a radial electric field

NASA Astrophysics Data System (ADS)

Liu, Rong; Chen, Xue; Ding, Zijing

2018-01-01

We consider the motion of a gravity-driven flow down a vertical fiber subjected to a radial electric field. This flow exhibits rich dynamics including the formation of droplets, or beads, driven by a Rayleigh-Plateau mechanism modified by the presence of gravity as well as the Maxwell stress at the interface. A spatiotemporal stability analysis is performed to investigate the effect of electric field on the absolute-convective instability (AI-CI) characteristics. We performed a numerical simulation on the nonlinear evolution of the film to examine the transition from CI to AI regime. The numerical results are in excellent agreement with the spatiotemporal stability analysis. The blowup behavior of nonlinear simulation predicts the formation of touchdown singularity of the interface due to the effect of electric field. We try to connect the blowup behavior with the AI-CI characteristics. It is found that the singularities mainly occur in the AI regime. The results indicate that the film may have a tendency to form very sharp tips due to the enhancement of the absolute instability induced by the electric field. We perform a theoretical analysis to study the behaviors of the singularities. The results show that there exists a self-similarity between the temporal and spatial distances from the singularities.

Electric field enhancement due to a saw-tooth asperity in a channel and implications on microscale gas breakdown

NASA Astrophysics Data System (ADS)

Venkattraman, Ayyaswamy

2014-10-01

The electric field enhancement due to an isolated saw-tooth asperity in an infinite channel is considered with the goal of providing some inputs to the choice of field enhancement factors used to describe microscale gas breakdown. The Schwarz-Christoffel transformation is used to map the interior of the channel to the upper half of the transformed plane. The expression for the electric field in the transformed plane is then used to determine the electric field distribution in the channel as well as field enhancement near the asperity. The effective field enhancement factor is determined and its dependence on operating and geometrical parameters is studied. While the effective field enhancement factor depends only weakly on the height of the asperity in comparison to the channel, it is influenced significantly by the base angles of the asperity. Due to the strong dependence of field emission current density on electric field, the effective field enhancement factor (βeff) is shown to vary rapidly with the applied electric field irrespective of the geometrical parameters. This variation is included in the analysis of microscale gas breakdown and compared with results obtained using a constant βeff as is done traditionally. Even though results for a varying βeff may be approximately reproduced using an equivalent constant βeff independent of E-field, it might be important for a range of operating conditions. This is confirmed by extracting βeff from experimental data for breakdown in argon microgaps with plane-parallel cathodes and comparing its dependence on the E-field. While the use of two-dimensional asperities is shown to be a minor disadvantage of the proposed approach in its current form, it can potentially help in developing predictive capabilities as opposed to treating βeff as a curve-fitting parameter.

Tuning the electronic properties and Schottky barrier height of the vertical graphene/MoS2 heterostructure by an electric gating

NASA Astrophysics Data System (ADS)

Nguyen, Chuong V.

2018-04-01

In this paper, the electronic properties and Schottky contact in graphene/MoS2 (G/MoS2) heterostructure under an applied electric field are investigated by means of the density functional theory. It can be seen that the electronic properties of the G/MoS2 heterostructure are preserved upon contacting owing to the weak van der Waals interaction. We found that the n-type Schottky contact is formed in the G/MoS2 heterostructure with the Schottky barrier height of 0.49 eV. Furthermore, both Schottky contact and Schottky barrier height in the G/MoS2 heterostructure could be controlled by the applied electric field. If a positive electric field of 4 V/nm is applied to the system, a transformation from the n-type Schottky contact to the p-type one was observed, whereas the system keeps an n-type Schottky contact when a negative electric field is applied. Our results may provide helpful information to design, fabricate, and understand the physics mechanism in the graphene-based two-dimensional van der Waals heterostructures like as G/MoS2 heterostructure.

Maxwell-Higgs equation on higher dimensional static curved spacetimes

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

Mulyanto, E-mail: mulyanto37@gmail.com; Akbar, Fiki Taufik, E-mail: ftakbar@fi.itb.ac.id; Gunara, Bobby Eka, E-mail: bobby@fi.itb.ac.id

In this paper we consider a class of solutions of Maxwell-Higgs equation in higher dimensional static curved spacetimes called Schwarzchild de-Sitter spacetimes. We obtain the general form of the electric fields and magnetic fields in background Schwarzchild de-Sitter spacetimes. However, determining the interaction between photons with the Higgs scalar fields is needed further studies.

Electrically reversible cracks in an intermetallic film controlled by an electric field

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

Liu, Z. Q.; Liu, J. H.; Biegalski, M. D.

Cracks in solid-state materials are typically irreversible. We report electrically reversible opening and closing of nanoscale cracks in an intermetallic thin film grown on a ferroelectric substrate driven by a small electric field (~0.83 kV/cm). Accordingly, a nonvolatile colossal electroresistance on-off ratio of more than 10 8 is measured across the cracks in the intermetallic film at room temperature. Cracks are easily formed with low-frequency voltage cycling and remain stable when the device is operated at high frequency, which offers intriguing potential for next-generation high-frequency memory applications. Moreover, endurance testing demonstrates that the opening and closing of such cracks canmore » reach over 10 7 cycles under 10-μs pulses, without catastrophic failure of the film.« less

Electrically reversible cracks in an intermetallic film controlled by an electric field

DOE PAGES

Liu, Z. Q.; Liu, J. H.; Biegalski, M. D.; ...

2018-01-03

Cracks in solid-state materials are typically irreversible. We report electrically reversible opening and closing of nanoscale cracks in an intermetallic thin film grown on a ferroelectric substrate driven by a small electric field (~0.83 kV/cm). Accordingly, a nonvolatile colossal electroresistance on-off ratio of more than 10 8 is measured across the cracks in the intermetallic film at room temperature. Cracks are easily formed with low-frequency voltage cycling and remain stable when the device is operated at high frequency, which offers intriguing potential for next-generation high-frequency memory applications. Moreover, endurance testing demonstrates that the opening and closing of such cracks canmore » reach over 10 7 cycles under 10-μs pulses, without catastrophic failure of the film.« less

Electric-field induced surface instabilities of soft dielectrics and their effects on optical transmittance and scattering

NASA Astrophysics Data System (ADS)

Shian, Samuel; Kjeer, Peter; Clarke, David R.

2018-03-01

When a voltage is applied to a percolative, mechanically compliant mat of carbon nanotubes (CNTs) on a smooth elastomer bilayer attached to an ITO coated glass substrate, the in-line optical transmittance decreases with increasing voltage. Two regimes of behavior have been identified based on optical scattering, bright field optical microscopy, and confocal optical microscopy. In the low field regime, the electric field produces a spatially inhomogeneous surface deformation of the elastomer that causes local variations in optical refraction and modulates the light transmittance. The spatial variation is associated with the distribution of the CNTs over the surface. At higher fields, above a threshold voltage, an array of pits in the surface form by a nucleation and growth mechanism and these also scatter light. The formation of pits, and creases, in the thickness of the elastomer, is due to a previously identified electro-mechanical surface instability. When the applied voltage is decreased from its maximum, the transmittance returns to its original value although there is a transmittance hysteresis and a complicated time response. When the applied voltage exceeds the threshold voltage, there can be remnant optical contrast associated with creasing of the elastomer and the recovery time appears to be dependent on local jamming of CNTs in areas where the pits formed. A potential application of this work as an electrically tunable privacy window or camouflaging devices is demonstrated.

A theoretical study of the dissociation of the sI methane hydrate induced by an external electric field

NASA Astrophysics Data System (ADS)

Luis, D. P.; Herrera-Hernández, E. C.; Saint-Martin, H.

2015-11-01

Molecular dynamics simulations in the equilibrium isobaric—isothermal (NPT) ensemble were used to examine the strength of an external electric field required to dissociate the methane hydrate sI structure. The water molecules were modeled using the four-site TIP4P/Ice analytical potential and methane was described as a simple Lennard-Jones interaction site. A series of simulations were performed at T = 260 K with P = 80 bars and at T = 285 K with P = 400 bars with an applied electric field ranging from 1.0 V nm-1 to 5.0 V nm-1. For both (T,P) conditions, applying a field greater than 1.5 V nm-1 resulted in the orientation of the water molecules such that an ice Ih-type structure was formed, from which the methane was segregated. When the simulations were continued without the external field, the ice-like structures became disordered, resulting in two separate phases: gas methane and liquid water.

Dependence of electrical and time stress in organic field effect transistor with low temperature forming gas treated Al2O3 gate dielectrics.

PubMed

Lee, Sunwoo; Chung, Keum Jee; Park, In-Sung; Ahn, Jinho

2009-12-01

We report the characteristics of the organic field effect transistor (OFET) after electrical and time stress. Aluminum oxide (Al2O3) was used as a gate dielectric layer. The surface of the gate oxide layer was treated with hydrogen (H2) and nitrogen (N2) mixed gas to minimize the dangling bond at the interface layer of gate oxide. According to the two stress parameters of electrical and time stress, threshold voltage shift was observed. In particular, the mobility and subthreshold swing of OFET were significantly decreased due to hole carrier localization and degradation of the channel layer between gate oxide and pentacene by electrical stress. Electrical stress is a more critical factor in the degradation of mobility than time stress caused by H2O and O2 in the air.

Unavoidable electric current caused by inhomogeneities and its influence on measured material parameters of thermoelectric materials

NASA Astrophysics Data System (ADS)

Song, K.; Song, H. P.; Gao, C. F.

2018-03-01

It is well known that the key factor determining the performance of thermoelectric materials is the figure of merit, which depends on the thermal conductivity (TC), electrical conductivity, and Seebeck coefficient (SC). The electric current must be zero when measuring the TC and SC to avoid the occurrence of measurement errors. In this study, the complex-variable method is used to analyze the thermoelectric field near an elliptic inhomogeneity in an open circuit, and the field distributions are obtained in closed form. Our analysis shows that an electric current inevitably exists in both the matrix and the inhomogeneity even though the circuit is open. This unexpected electric current seriously affects the accuracy with which the TC and SC are measured. These measurement errors, both overall and local, are analyzed in detail. In addition, an error correction method is proposed based on the analytical results.

Wireless tamper detection sensor and sensing system

NASA Technical Reports Server (NTRS)

Woodard, Stanley E. (Inventor); Taylor, Bryant D. (Inventor)

2011-01-01

A wireless tamper detection sensor is defined by a perforated electrical conductor. The conductor is shaped to form a geometric pattern between first and second ends thereof such that the conductor defines an open-circuit that can store and transfer electrical and magnetic energy. The conductor resonates in the presence of a time-varying magnetic field to generate a harmonic response. The harmonic response changes when the conductor experiences a change in its geometric pattern due to severing of the conductor along at least a portion of the perforations. A magnetic field response recorder is used to wirelessly transmit the time-varying magnetic field and wirelessly detecting the conductor's harmonic response.

Novel non-equilibrium modelling of a DC electric arc in argon

NASA Astrophysics Data System (ADS)

Baeva, M.; Benilov, M. S.; Almeida, N. A.; Uhrlandt, D.

2016-06-01

A novel non-equilibrium model has been developed to describe the interplay of heat and mass transfer and electric and magnetic fields in a DC electric arc. A complete diffusion treatment of particle fluxes, a generalized form of Ohm’s law, and numerical matching of the arc plasma with the space-charge sheaths adjacent to the electrodes are applied to analyze in detail the plasma parameters and the phenomena occurring in the plasma column and the near-electrode regions of a DC arc generated in atmospheric pressure argon for current levels from 20 A up to 200 A. Results comprising electric field and potential, current density, heating of the electrodes, and effects of thermal and chemical non-equilibrium are presented and discussed. The current-voltage characteristic obtained is in fair agreement with known experimental data. It indicates a minimum for arc current of about 80 A. For all current levels, a field reversal in front of the anode accompanied by a voltage drop of (0.7-2.6) V is observed. Another field reversal is observed near the cathode for arc currents below 80 A.

Influence of the solid dielectric over the electric field from the ozone cell gap with double dielectric barrier

NASA Astrophysics Data System (ADS)

Ganea, I.

2017-05-01

The distilled water has the advantage of high value dielectric constant (ε = 81) in relation to ceramic glass materials, currently used for constructing the dielectric barrier. It was necessary to build a thin-walled enclosure of solid insulating material that contain distilled water to achieve a dielectric barrier. This was necessary to avoid exposing the liquid to the direct action of ozone. Dielectric permittivity of the solid dielectric material and the thickness of these walls have diminished the value of the electric field form the gaseous gap of the ozone cell compared to the case with the dielectric barrier from distilled water. The author of this work deduced theoretical relationships that express the values of the electric field intensity in the gap of the cell with two dielectrics and compared them with similar relationships of the intensity of the electric field from the gap of the ozone cell with one dielectric. In this work the author presenting experimental results which confirm the theoretical deducting regarding the use of the solid dielectric as enclosure for the liquid dielectric.

Double relaxation via AdS/CFT

NASA Astrophysics Data System (ADS)

Amiri-Sharifi, S.; Ali-Akbari, M.; Kishani-Farahani, A.; Shafie, N.

2016-08-01

We exploit the AdS/CFT correspondence to investigate thermalization in an N = 2 strongly coupled gauge theory including massless fundamental matter (quark). More precisely, we consider the response of a zero temperature state of the gauge theory under influence of an external electric field which leads to a time-dependent current. The holographic dual of the above set-up is given by introducing a time-dependent electric field on the probe D7-brane embedded in an AdS5 ×S5 background. In the dual gravity theory an apparent horizon forms on the brane which, according to AdS/CFT dictionary, is the counterpart of the thermalization process in the gauge theory side. We classify different functions for time-dependent electric field and study their effect on the apparent horizon formation. In the case of pulse functions, where the electric field varies from zero to zero, apart from non-equilibrium phase, we observe the formation of two separate apparent horizons on the brane. This means that the state of the gauge theory experiences two different temperature regimes during its time evolution.

Modeling and simulation of dielectrophoretic collective dynamics in a suspension of polarizable particles under the action of a gradient AC electric field.

PubMed

Tada, Shigeru; Shen, Yan; Qiu, Zhiyong

2017-06-01

When a suspension of polarizable particles is subjected to a gradient AC electric field, the particles exhibit collective motion due to an interaction between the dipole induced in the particles and the spatial gradient of the electric field; this is known as dielectrophoresis. In the present study, the collective dynamics of suspended particles in a parallel-plate electric chamber was investigated by simulating numerically the trajectories of individual particles under the action of combined dielectrophoretic and dipole-dipole interparticle forces. The particles were transported by the dielectrophoretic forces toward the grounded electrodes. Before long, when the particles approached the site of the minimum field strength, attractive/repulsive interparticle forces became dominant and acted among the particles attempting to form a column-like cluster, having the particles distribution in concentric circles in its cross-section, in line with the centerline of the grounded electrodes. Our results also well reproduced the transient particle aggregation that was observed experimentally. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Theory of Dielectric Breakdown in Randomly Inhomogeneous Materials

NASA Astrophysics Data System (ADS)

Gyure, Mark Franklin

1990-01-01

Two models of dielectric breakdown in disordered metal-insulator composites have been developed in an attempt to explain in detail the greatly reduced breakdown electric field observed in these materials. The first model is a two dimensional model in which the composite is treated as a random array of conducting cylinders embedded in an otherwise uniform dielectric background. The two dimensional samples are generated by the Monte Carlo method and a discretized version of the integral form of Laplace's equation is solved to determine the electric field in each sample. Breakdown is modeled as a quasi-static process by which one breakdown at a time occurs at the point of maximum electric field in the system. A cascade of these local breakdowns leads to complete dielectric failure of the system after which the breakdown field can be determined. A second model is developed that is similar to the first in terms of breakdown dynamics, but uses coupled multipole expansions of the electrostatic potential centered at each particle to obtain a more computationally accurate and faster solution to the problem of determining the electric field at an arbitrary point in a random medium. This new algorithm allows extension of the model to three dimensions and treats conducting spherical inclusions as well as cylinders. Successful implementation of this algorithm relies on the use of analytical forms for off-centered expansions of cylindrical and spherical harmonics. Scaling arguments similar to those used in theories of phase transitions are developed for the breakdown field and these arguments are discussed in context with other theories that have been developed to explain the break-down behavior of random resistor and fuse networks. Finally, one of the scaling arguments is used to predict the breakdown field for some samples of solid fuel rocket propellant tested at the China Lake Naval Weapons Center and is found to compare quite well with the experimentally measured breakdown fields.

Precessional switching of antiferromagnets by electric field induced Dzyaloshinskii-Moriya torque

NASA Astrophysics Data System (ADS)

Kim, T. H.; Grünberg, P.; Han, S. H.; Cho, B. K.

2018-05-01

Antiferromagnetic insulators (AFIs) have attracted much interest from many researchers as promising candidates for use in ultrafast, ultralow-dissipation spintronic devices. As a fast method of reversing magnetization, precessional switching is realized when antiferromagnetic Néel orders l =(s1+s2 )/2 surmount the magnetic anisotropy or potential barrier in a given magnetic system, which is described well by the antiferromagnetic plane pendulum (APP) model. Here, we report that, as an alternative switching scenario, the direct coupling of an electric field with Dzyaloshinskii-Moriya (DM) interaction, which stems from spin-orbit coupling, is exploited for optimal switching. We derive the pendulum equation of motion of antiferromagnets, where DM torque is induced by a pulsed electric field. The temporal DM interaction is found to not only be in the form of magnetic torques (e.g., spin-orbit torque or magnetic field) but also modifies the magnetic potential that limits l 's activity; as a result, appropriate controls (e.g., direction, magnitude, and pulse shape) of the induced DM vector realize deterministic reversal in APP. The results present an approach for the control of a magnetic storage device by means of an electric field.

Towards multicaloric effect with ferroelectrics

NASA Astrophysics Data System (ADS)

Liu, Yang; Zhang, Guangzu; Li, Qi; Bellaiche, Laurent; Scott, James F.; Dkhil, Brahim; Wang, Qing

2016-12-01

Utilizing thermal changes in solid-state materials strategically offers caloric-based alternatives to replace current vapor-compression technology. To make full use of multiple forms of the entropy and achieve higher efficiency for designs of cooling devices, the multicaloric effect appears as a cutting-edge concept encouraging researchers to search for multicaloric materials with outstanding caloric properties. Here we report the multicaloric effect in BaTi O3 single crystals driven simultaneously by mechanical and electric fields and described via a thermodynamic phenomenological model. It is found that the multicaloric behavior is mainly dominated by the mechanical field rather than the electric field, since the paraelectric-to-ferroelectric transition is more sensitive to mechanical field than to electric field. The use of uniaxial stress competes favorably with pressure due to its much higher caloric strength and negligible elastic thermal change. It is revealed that multicaloric response can be significantly larger than just the sum of mechanocaloric and electrocaloric effects in temperature regions far above the Curie temperature but cannot exceed this limit near the Curie temperature. Our results also show the advantage of the multicaloric effect over the mechanically mediated electrocaloric effect or electrically mediated mechanocaloric effect. Our findings therefore highlight the importance of ferroelectric materials to develop multicaloric cooling.

On the generation of double layers from ion- and electron-acoustic instabilities

DOE PAGES

Fu, Xiangrong; Cowee, Misa M.; Gary, Stephen Peter; ...

2016-03-17

A plasma double layer (DL) is a nonlinear electrostatic structure that carries a uni-polar electric field parallel to the background magnetic field due to local charge separation. Past studies showed that DLs observed in space plasmas are mostly associated with the ion acoustic instability. Recent Van Allen Probes observations of parallel electric fields traveling much faster than the ion acoustic speed have motivated a computational study to test the hypothesis that a new type of DLs – electron acoustic DLs – generated from the electron acoustic instability are responsible for these electric fields. Nonlinear particle-in-cell simulations yield negative results, i.e.more » the hypothetical electron acoustic DLs cannot be formed in a way similar to ion acoustic DLs. We find that linear theory analysis and the simulations show that the frequencies of electron acoustic waves are too high for ions to respond and maintain charge separation required by DLs. However, our results do show that local density perturbations in a two-electron-component plasma can result in unipolar-like electric fields that propagate at the electron thermal speed, suggesting another potential explanation for the observations.« less

On the generation of double layers from ion- and electron-acoustic instabilities

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

Fu, Xiangrong, E-mail: xrfu@lanl.gov; Cowee, Misa M.; Winske, Dan

2016-03-15

A plasma double layer (DL) is a nonlinear electrostatic structure that carries a uni-polar electric field parallel to the background magnetic field due to local charge separation. Past studies showed that DLs observed in space plasmas are mostly associated with the ion acoustic instability. Recent Van Allen Probes observations of parallel electric field structures traveling much faster than the ion acoustic speed have motivated a computational study to test the hypothesis that a new type of DLs—electron acoustic DLs—generated from the electron acoustic instability are responsible for these electric fields. Nonlinear particle-in-cell simulations yield negative results, i.e., the hypothetical electronmore » acoustic DLs cannot be formed in a way similar to ion acoustic DLs. Linear theory analysis and the simulations show that the frequencies of electron acoustic waves are too high for ions to respond and maintain charge separation required by DLs. However, our results do show that local density perturbations in a two-electron-component plasma can result in unipolar-like electric field structures that propagate at the electron thermal speed, suggesting another potential explanation for the observations.« less

Near-membrane electric field calcium ion dehydration.

PubMed

Barger, James P; Dillon, Patrick F

2016-12-01

The dehydration of ion-water complexes prior to ion channel transit has focused on channel protein-mediated dissociation of water. Ion dehydration by the membrane electric field has not previously been considered. Near membrane electric fields have previously been shown to cause the disassociation of non-covalently bound small molecule-small molecule, small molecule-protein, and protein-protein complexes. It is well known that cosmotropic, structure making ions such as calcium and sodium significantly bind multiple water ions in solution. It is also known that these ions are often not hydrated as they pass through membrane ion channels. Using capillary electrophoresis, the range of electric fields needed to strip water molecules from calcium ions has been measured. Ion migration velocity is a linear function of the electric field. At low electric fields, the migration rate of calcium ion was shown to be linearly related to the applied electric field. Using a form of the Stoke's equation applicable to ion migration, the hydrated calcium radius was found to be 0.334nm, corresponding to a water hydration shell of 5.09 water molecules. At higher electric fields, the slope of the calcium migration velocity as a function of the electric field increased, which was modeled as a decrease in the radius of the migrating ion as the water was removed. Using a tanh function to model the transition of the ion from a hydrated to a stripped state, the transition had a midpoint at 446V/cm, and was 88% complete at 587V/cm with a correlation coefficient of 0.9996. The migration velocity of the stripped calcium ion was found to be a function of both the decrease in radius and an increase in the effective, electronic viscosity of the dipole medium through which the dehydrated ion moved. The size of the electric field needed to dehydrate calcium occurs 6-7nm from the cell membrane. Calcium ions within this distance from the membrane will be devoid of water molecules when they reach the calcium selective channel pore entrances, all known to be approximately 1-2nm from the membrane. No matter what the calcium pore structure, calcium ions reaching the channel entrance will be devoid of a water shell. Copyright © 2016 Elsevier Ltd. All rights reserved.

Wireless sensing system for non-invasive monitoring of attributes of contents in a container

NASA Technical Reports Server (NTRS)

Woodard, Stanley E. (Inventor)

2010-01-01

A wireless sensing system monitors the level, temperature, magnetic permeability and electrical dielectric constant of a non-gaseous material in a container. An open-circuit electrical conductor is shaped to form a two-dimensional geometric pattern that can store and transfer electrical and magnetic energy. The conductor resonates in the presence of a time-varying magnetic field to generate a harmonic response. The conductor is mounted in an environmentally-sealed housing. A magnetic field response recorder wirelessly transmits the time-varying magnetic field to power the conductor, and wirelessly detects the harmonic response that is an indication of at least one of level of the material in the container, temperature of the material in the container, magnetic permeability of the material in the container, and dielectric constant of the material in the container.

Pulsed plasmoid electric propulsion

NASA Technical Reports Server (NTRS)

Bourque, Robert F.; Parks, Paul B.; Tamano, Teruo

1990-01-01

A method of electric propulsion is explored where plasmoids such as spheromaks and field reversed configurations (FRC) are formed and then allowed to expand down a diverging conducting shell. The plasmoids contain a toroidal electric current that provides both heating and a confining magnetic field. They are free to translate because there are no externally supplied magnetic fields that would restrict motion. Image currents in the diverging conducting shell keep the plasmoids from contacting the wall. Because these currents translate relative to the wall, losses due to magnetic flux diffusion into the wall are minimized. During the expansion of the plasma in the diverging cone, both the inductive and thermal plasma energy are converted to directed kinetic energy producing thrust. Specific impulses can be in the 4000 to 20000 sec range with thrusts from 0.1 to 1000 Newtons, depending on available power.

The Analysis of a Vortex Type Magnetohydrodynamic Induction Generator

NASA Technical Reports Server (NTRS)

Lengyel, L. L.

1962-01-01

Consideration it is given to the performance to the characteristics of an AC magnetohydrodynamic power generator, A rotating magnetic field is imposed on the vortex flow of an electrically conducting fluid, which is injected tangentially into an annulus formed by two nonconducting concentric cylinders and two nonconducting end plates. A perturbation technique is used to determine the two dimensional velocity and three dimensional electromagnetic field and current distributions. Finally, the generated power, the ohmic losses, the effective power and the electrical efficiency of the converter system are calculated.

Propagation Modelling and Decision Aids for Communications, Radar and Navigation Systems (La Modelisation de la Propagation et Aides a la Decision Pour les Sysemes de elecommunicaions, de Radar et de Navigation)

DTIC Science & Technology

1994-09-01

the refractive index i. can be density, temperature , ion composition, ionospheric determined from a simplified form of the Appleton- electric field...see Cannon 119941. the electron density profile is based upon the underlying neutral composition. temperature and wind together with electric field...in many of the newer HF predictions decision software , NSSDC/WDC-A-R&S 90-19, National Space aids. They also provide a very useful stand alone

Generalization of the lightning electromagnetic equations of Uman, McLain, and Krider based on Jefimenko equations

DOE PAGES

Shao, Xuan-Min

2016-04-12

The fundamental electromagnetic equations used by lightning researchers were introduced in a seminal paper by Uman, McLain, and Krider in 1975. However, these equations were derived for an infinitely thin, one-dimensional source current, and not for a general three-dimensional current distribution. In this paper, we introduce a corresponding pair of generalized equations that are determined from a three-dimensional, time-dependent current density distribution based on Jefimenko's original electric and magnetic equations. To do this, we derive the Jefimenko electric field equation into a new form that depends only on the time-dependent current density similar to that of Uman, McLain, and Krider,more » rather than on both the charge and current densities in its original form. The original Jefimenko magnetic field equation depends only on current, so no further derivation is needed. We show that the equations of Uman, McLain, and Krider can be readily obtained from the generalized equations if a one-dimensional source current is considered. For the purpose of practical applications, we discuss computational implementation of the new equations and present electric field calculations for a three-dimensional, conical-shape discharge.« less

Auroral particles

NASA Technical Reports Server (NTRS)

Evans, David S.

1987-01-01

The problems concerning the aurora posed prior to the war are now either solved in principle or were restated in a more fundamental form. The pre-war hypothesis concerning the nature of the auroral particles and their energies was fully confirmed, with the exception that helium and oxygen ions were identified as participating in the auroral particle precipitation in addition to the protons. The nature of the near-Earth energization processes affecting auroral particles was clarified. Charged particle trajectories in various electric field geometries were modeled. The physical problems have now moved from determining the nature and geometry of the electric fields, which accelerate charged particles near the Earth, to accounting for the existence of these electric fields as a natural consequence of the solar wind's interaction with Earth. Ultimately the reward in continuing the work in auroral and magnetospheric particle dynamics will be a deeper understanding of the subtleties of classical electricity and magnetism as applied to situations not blessed with well-defined and invariant geometries.

Micro-cones on a liquid interface in high electric field: Ionization effects

NASA Astrophysics Data System (ADS)

Subbotin, Andrey V.; Semenov, Alexander N.

2018-02-01

We formulate and explore electrohydrodynamic equations for conductive liquids taking dissociation/recombination processes into account and discover a novel type of liquid cones which carry both surface and net bulk charge and can be formed on a liquid interface in an electric field. The bulk charge is generated by the corona discharge due to a high electric field at the cone apex. We establish correlation between the cone angle and physical parameters of the liquid on the one hand and the electric current passing through the cone on the other hand. It is shown that the current strongly increases when the cone angle tends to a critical value which is a function of the dielectric permittivity of the liquid. The cone stability with respect to axially symmetric perturbations is analyzed. It is shown that the cones with apex angles close to the critical angle are likely to be stable. The effect of the imposed flow on the cone apex stability is also discussed.

Definition of Shifts of Optical Transitions Frequencies due to Pulse Perturbation Action by the Photon Echo Signal Form

NASA Astrophysics Data System (ADS)

Lisin, V. N.; Shegeda, A. M.; Samartsev, V. V.

2015-09-01

A relative phase shift between the different groups of excited dipoles, which appears as result of its frequency splitting due to action of a pulse of electric or magnetic fields, depends on a time, if the pulse overlaps in time with echo-pulse. As а consequence, the echo waveform is changed. The echo time form is modulated. The inverse modulation period well enough approximates Zeeman and pseudo-Stark splitting in the cases of magnetic and, therefore, electrical fields. Thus the g-factors of ground 4I15/2 and excited 4F9/2 optical states of Er3+ ion in LuLiF4 and YLiF4 have been measured and pseudo-Stark shift of R1 line in ruby has been determined.

Switchable diode effect in oxygen vacancy-modulated SrTiO3 single crystal

NASA Astrophysics Data System (ADS)

Pan, Xinqiang; Shuai, Yao; Wu, Chuangui; Luo, Wenbo; Sun, Xiangyu; Zeng, Huizhong; Bai, Xiaoyuan; Gong, Chaoguan; Jian, Ke; Zhang, Lu; Guo, Hongliang; Tian, Benlang; Zhang, Wanli

2017-09-01

SrTiO3 (STO) single crystal wafer was annealed in vacuum, and co-planar metal-insulator-metal structure of Pt/Ti/STO/Ti/Pt were formed by sputtering Pt/Ti electrodes onto the surface of STO after annealing. The forming-free resistive switching behavior with self-compliance property was observed in the sample. The sample showed switchable diode effect, which is explained by a simple model that redistribution of oxygen vacancies (OVs) under the external electric field results in the formation of n-n+ junction or n+-n junction (n donated n-type semiconductor; n+ donated heavily doped n-type semiconductor). The self-compliance property is also interpreted by the formation of n-n+/n+-n junction caused by the migration of the OVs under the electric field.

Positrons as interface-sensitive probes of polar semiconductor heterostructures

NASA Astrophysics Data System (ADS)

Makkonen, I.; Snicker, A.; Puska, M. J.; Mäki, J.-M.; Tuomisto, F.

2010-07-01

Group-III nitrides in their wurtzite crystal structure are characterized by large spontaneous polarization and significant piezoelectric contributions in heterostructures formed of these materials. Polarization discontinuities in polar heterostructures grown along the (0001) direction result in huge built-in electric fields on the order of megavolt per centimeter. We choose the III-nitride heterostructures as archetypal representatives of polar heterostructures formed of semiconducting or insulating materials and study the behavior of positrons in these structures using first-principles electronic-structure theory supported by positron annihilation experiments for bulk systems. The strong electric fields drive positrons close to interfaces, which is clearly seen in the predicted momentum distributions of annihilating electron-positron pairs as changes relative to the constituent bulk materials. Implications of the effect to positron defect studies of polar heterostructures are addressed.

Dynamical features and electric field strengths of double layers driven by currents. [in auroras

NASA Technical Reports Server (NTRS)

Singh, N.; Thiemann, H.; Schunk, R. W.

1985-01-01

In recent years, a number of papers have been concerned with 'ion-acoustic' double layers. In the present investigation, results from numerical simulations are presented to show that the shapes and forms of current-driven double layers evolve dynamically with the fluctuations in the current through the plasma. It is shown that double layers with a potential dip can form even without the excitation of ion-acoustic modes. Double layers in two-and one-half-dimensional simulations are discussed, taking into account the simulation technique, the spatial and temporal features of plasma, and the dynamical behavior of the parallel potential distribution. Attention is also given to double layers in one-dimensional simulations, and electrical field strengths predicted by two-and one-half-dimensional simulations.

Interaction of biological systems with static and ELF electric and magnetic fields

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

Anderson, L.E.; Kelman, B.J.; Weigel, R.J.

1987-01-01

Although background levels of atmospheric electric and geomagnetic field levels are extremely low, over the past several decades, human beings and other life forms on this planet have been subjected to a dramatically changing electromagnetic milieu. An exponential increase in exposure to electromagnetic fields has occurred, largely because of such technological advances as the growth of electrical power generation and transmission systems, the increased use of wireless communications, and the use of radar. In addition, electromagnetic field generating devices have proliferated in industrial plants, office buildings, homes, public transportation systems, and elsewhere. Although significant increases have occurred in electromagnetic fieldmore » strenghths spanning all frequency ranges, this symposium addresses only the impact of these fields at static and extremely low frequencies (ELF), primarily 50 and 60 Hz. This volume contains the proceedings of the symposium entitled /open quotes/Interaction of biological systems with static and ELF electric and magnetic fields/close quotes/. The purpose of the symposium was to provide a forum for discussions of all aspects of research on the interaction of static and ELF electromagnetic fields with biological systems. These systems include simple biophysical models, cell and organ preparations, whole animals, and man. Dosimetry, exposure system design, and artifacts in ELF bioeffects research were also addressed, along with current investigations that examine fundamental mechanisms of interactions between the fields and biological processes. Papers are indexed separately.« less

Electric field measurement of two commercial active/sham coils for transcranial magnetic stimulation.

PubMed

Smith, James Evan; Peterchev, Angel V

2018-06-22

Sham TMS coils isolate the ancillary effects of their active counterparts, but typically induce low-strength electric fields (E-fields) in the brain, which could be biologically active. We measured the E-fields induced by two pairs of commonly-used commercial active/sham coils. Approach: E-field distributions of the active and sham configurations of the Magstim 70 mm AFC and MagVenture Cool-B65 A/P coils were measured over a 7-cm-radius, hemispherical grid approximating the cortical surface. Peak E-field strength was recorded over a range of pulse amplitudes. Main results: The Magstim and MagVenture shams induce peak E-fields corresponding to 25.3% and 7.72% of their respective active values. The MagVenture sham has an E-field distribution shaped like its active counterpart. The Magstim sham induces nearly zero E-field under the coil's center, and its peak E-field forms a diffuse oval 3-7 cm from the center. Electrical scalp stimulation paired with the MagVenture sham is estimated to increase the sham E-field in the brain up to 10%. Significance: Different commercial shams induce different E-field strengths and distributions in the brain, which should be considered in interpreting outcomes of sham stimulation. © 2018 IOP Publishing Ltd.

Electrically Driving Donor Spin Qubits in Silicon Using Photonic Bandgap Resonators

NASA Astrophysics Data System (ADS)

Sigillito, A. J.; Tyryshkin, A. M.; Lyon, S. A.

In conventional experiments, donor nuclear spin qubits in silicon are driven using radiofrequency (RF) magnetic fields. However, magnetic fields are difficult to confine at the nanoscale, which poses major issues for individually addressable qubits and device scalability. Ideally one could drive spin qubits using RF electric fields, which are easy to confine, but spins do not naturally have electric dipole transitions. In this talk, we present a new method for electrically controlling nuclear spin qubits in silicon by modulating the hyperfine interaction between the nuclear spin qubit and the donor-bound electron. By fabricating planar superconducting photonic bandgap resonators, we are able to use pulsed electron-nuclear double resonance (ENDOR) techniques to selectively probe both electrically and magnetically driven transitions for 31P and 75As nuclear spin qubits. The electrically driven spin resonance mechanism allows qubits to be driven at either their transition frequency, or at one-half their transition frequency, thus reducing bandwidth requirements for future quantum devices. Moreover, this form of control allows for higher qubit densities and lower power requirements compared to magnetically driven schemes. In our proof-of-principle experiments we demonstrate electrically driven Rabi frequencies of approximately 50 kHz for widely spaced (10 μm) gates which should be extendable to MHz for nanoscale devices.

Artificial stimulation of auroral electron acceleration by intense field aligned currents

NASA Technical Reports Server (NTRS)

Holmgren, G.; Bostrom, R.; Kelley, M. C.; Kintner, P. M.; Lundin, R.; Bering, E. A.; Sheldon, W. R.; Fahleson, U. V.

1979-01-01

A cesium-doped high explosion was detonated at 165 km altitude in the auroral ionosphere during quiet conditions. An Alfven wave pulse with a 200-mV/m electric field was observed, with the peak occurring 135 ms after the explosion at a distance of about 1 km. The count rate of fixed energy 2-keV electron detectors abruptly increased at 140 ms, peaked at 415 ms, and indicated a downward field-aligned beam of accelerated electrons. An anomalously high-field aligned beam of backscattered electrons was also detected. The acceleration is interpreted as due to production of an electrostatic shock or double layer between 300 and 800 km altitude. The structure was probably formed by an instability of the intense field-aligned currents in the Alfven wave launched by the charge-separation electric field due to the explosion.

Aircraft electric field measurements: Calibration and ambient field retrieval

NASA Technical Reports Server (NTRS)

Koshak, William J.; Bailey, Jeff; Christian, Hugh J.; Mach, Douglas M.

1994-01-01

An aircraft locally distorts the ambient thundercloud electric field. In order to determine the field in the absence of the aircraft, an aircraft calibration is required. In this work a matrix inversion method is introduced for calibrating an aircraft equipped with four or more electric field sensors and a high-voltage corona point that is capable of charging the aircraft. An analytic, closed form solution for the estimate of a (3 x 3) aircraft calibration matrix is derived, and an absolute calibration experiment is used to improve the relative magnitudes of the elements of this matrix. To demonstrate the calibration procedure, we analyze actual calibration date derived from a Lear jet 28/29 that was equipped with five shutter-type field mill sensors (each with sensitivities of better than 1 V/m) located on the top, bottom, port, starboard, and aft positions. As a test of the calibration method, we analyze computer-simulated calibration data (derived from known aircraft and ambient fields) and explicitly determine the errors involved in deriving the variety of calibration matrices. We extend our formalism to arrive at an analytic solution for the ambient field, and again carry all errors explicitly.

A Nontoxic Barlow's Wheel

ERIC Educational Resources Information Center

Daffron, John A.; Greenslade, Thomas B., Jr.

2015-01-01

Barlow's wheel has been a favorite demonstration since its invention by Peter Barlow (1776-1862) in 1822. In the form shown in Fig. 1, it represents the first electric motor. The interaction between the electric current passing from the axle of the wheel to the rim and the magnetic field produced by the U-magnet produces a torque that turns…

Analyzing intrinsic plasmonic chirality by tracking the interplay of electric and magnetic dipole modes.

PubMed

Hu, Li; Huang, Yingzhou; Pan, Lujun; Fang, Yurui

2017-09-11

Plasmonic chirality represents significant potential for novel nanooptical devices due to its association with strong chiroptical responses. Previous reports on plasmonic chirality mechanism mainly focus on phase retardation and coupling. In this paper, we propose a model similar to the chiral molecules for explaining the intrinsic plasmonic chirality mechanism of varies 3D chiral structures quantitatively based on the interplay and mixing of electric and magnetic dipole modes (directly from electromagnetic field numerical simulations), which forms mixed electric and magnetic polarizability.

Cosmic Rays and Clouds, 1. Formation of Lead Mesoatoms In Neutron Monitor By Soft Negative Muons and Expected Atmospheric Electric Field Effect In The Cosmic Ray Neutron Component

NASA Astrophysics Data System (ADS)

Dorman, L. I.; Dorman, I. V.

We extend our model (Dorman and Dorman, 1995) of cosmic ray atmospheric electric field effect on the case of neutron monitor. We take into account that about 0.07 of neu- tron monitor counting rate caused by negative soft muons captured by lead nucleons and formed mesoatoms with generation of several MeV energy neutrons from lead. In this case the neutron monitor or neutron supermonitor works as analyzer which de- tects muons of only one, negative sign. It is very important because the atmospheric electric field effect have opposite signs for positive and negative muons that main part of this effect in the muon telescope or in ionization chamber is compensated and we can observe only small part of total effect of one sign muons. On the basis of our gen- eral theory of cosmic ray meteorological effects with taking into account of negative soft muon acceleration and deceleration in the Earth atmosphere (in dependence of di- rection and intensity of electric field) we discuss the possibility of existing this effect in cosmic ray neutron component and made some rough estimations. REFERENCES: Dorman L.I. and Dorman I.V., 1995. "Cosmic-ray atmospheric electric field effects". Canadian J. of Physics, Vol. 73, pp. 440-443.

Hypervelocity gun. [using both electric and chemical energy for projectile propulsion

NASA Technical Reports Server (NTRS)

Ford, F. C.; Biehl, A. J. (Inventor)

1965-01-01

A velocity amplifier system which uses both electric and chemical energy for projectile propulsion is provided in a compact hypervelocity gun suitable for laboratory use. A relatively heavy layer of a tamping material such as concrete encloses a loop of an electrically conductive material. An explosive charge at least partially surrounding the loop is adapted to collapse the loop upon detonation of the charge. A source of electricity charges the loop through two leads, and an electric switch which is activated by the charge explosive charge, disconnects the leads from the source of electricity and short circuits them. An opening in the tamping material extends to the loop and forms a barrel. The loop, necked down in the opening, forms the sabot on which the projectile is located. When the loop is electrically charged and the explosive detonated, the loop is short circuited and collapsed thus building up a magnetic field which acts as a sabot catcher. The sabot is detached from the loop and the sabot and projectile are accelerated to hypervelocity.

Polymer composites with graphene nanofillers: electrical properties and applications.

PubMed

Tjong, Sie Chin

2014-02-01

Graphene with extraordinary high elastic modulus and excellent electrical conductivity has good prospects for use as the filler material for fabricating novel polymer composites designed for electrostatic discharge and EMI shielding protection, field emission, gas sensor, and fuel cell applications. Large amounts of graphene oxide (GO) can be obtained by wet chemical oxidation of graphite into a mixture of concentrated sulfuric acid, sodium nitrate and potassium permanganate. Accordingly, carbon atoms in the basal plane and edges of GO are decorated with oxygenated functional groups, forming an electrical insulator. To restore electrical conductivity, chemical reduction or thermal annealing is needed to eliminate oxygenated groups of GO. However, such treatments induce internal defects and remove oxygenated atoms of GO partially. The remnant-oxygenated groups affect electrical conductivity of graphene greatly. Nevertheless, reduced graphene oxide and thermally reduced graphene oxide are sufficiently conductive to form polymer nanocomposites at very low percolation threshold. This review provides the fundamentals and state-of-the-art developments in the fabrication methods and electrical property characterizations as well as the applications of novel graphene/polymer nanocomposites. Particular attention is paid to their processing-structural-electrical property relationships.

Physics of GAM-initiated L-H transition in a tokamak

NASA Astrophysics Data System (ADS)

Askinazi, L. G.; Belokurov, A. A.; Bulanin, V. V.; Gurchenko, A. D.; Gusakov, E. Z.; Kiviniemi, T. P.; Lebedev, S. V.; Kornev, V. A.; Korpilo, T.; Krikunov, S. V.; Leerink, S.; Machielsen, M.; Niskala, P.; Petrov, A. V.; Tukachinsky, A. S.; Yashin, A. Yu; Zhubr, N. A.

2017-01-01

Based on experimental observations using the TUMAN-3M and FT-2 tokamaks, and the results of gyrokinetic modeling of the interplay between turbulence and the geodesic acoustic mode (GAM) in these installations, a simple model is proposed for the analysis of the conditions required for L-H transition triggering by a burst of radial electric field oscillations in a tokamak. In the framework of this model, one-dimensional density evolution is considered to be governed by an anomalous diffusion coefficient dependent on radial electric field shear. The radial electric field is taken as the sum of the oscillating term and the quasi-stationary one determined by density and ion temperature gradients through a neoclassical formula. If the oscillating field parameters (amplitude, frequency, etc) are properly adjusted, a transport barrier forms at the plasma periphery and sustains after the oscillations are switched off, manifesting a transition into the high confinement mode with a strong inhomogeneous radial electric field and suppressed transport at the plasma edge. The electric field oscillation parameters required for L-H transition triggering are compared with the GAM parameters observed at the TUMAN-3M (in the discharges with ohmic L-H transition) and FT-2 tokamaks (where no clear L-H transition was observed). It is concluded based on this comparison that the GAM may act as a trigger for the L-H transition, provided that certain conditions for GAM oscillation and tokamak discharge are met.

Ionization of Rydberg atoms colliding with a metal surface

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

Sjakste, J.; Borisov, A. G.; Gauyacq, J. P.

2006-04-15

We report on a theoretical study of the ionization process of Xe* Rydberg atoms colliding with a metal surface, in the presence of an external electric field. The evolution of the Xe* outer electron is studied by a wave packet propagation approach, allowing to include all dynamical aspects of the collision, in particular nonadiabatic inter-Rydberg transitions. We investigate how the different Xe* Stark states formed in the external field couple together and ionize on the surface and how the different polarizations of the electronic cloud in the Xe* states are reflected in their ionization properties. We show that the presencemore » of the external electric field can significantly perturb the dynamics of the ionization process. Our results account for recent results from Dunning et al. [Nucl. Inst. Meth. B 203, 69 (2003)]. In particular, it is explained how the external electric field present in the experimental procedure of Dunning et al. leads to the apparent absence of a polarization effect in the ionization process.« less

Drift waves, intense parallel electric fields, and turbulence associated with asymmetric magnetic reconnection at the magnetopause

NASA Astrophysics Data System (ADS)

Ergun, R. E.; Chen, L.-J.; Wilder, F. D.; Ahmadi, N.; Eriksson, S.; Usanova, M. E.; Goodrich, K. A.; Holmes, J. C.; Sturner, A. P.; Malaspina, D. M.; Newman, D. L.; Torbert, R. B.; Argall, M. R.; Lindqvist, P.-A.; Burch, J. L.; Webster, J. M.; Drake, J. F.; Price, L.; Cassak, P. A.; Swisdak, M.; Shay, M. A.; Graham, D. B.; Strangeway, R. J.; Russell, C. T.; Giles, B. L.; Dorelli, J. C.; Gershman, D.; Avanov, L.; Hesse, M.; Lavraud, B.; Le Contel, O.; Retino, A.; Phan, T. D.; Goldman, M. V.; Stawarz, J. E.; Schwartz, S. J.; Eastwood, J. P.; Hwang, K.-J.; Nakamura, R.; Wang, S.

2017-04-01

Observations of magnetic reconnection at Earth's magnetopause often display asymmetric structures that are accompanied by strong magnetic field (B) fluctuations and large-amplitude parallel electric fields (E||). The B turbulence is most intense at frequencies above the ion cyclotron frequency and below the lower hybrid frequency. The B fluctuations are consistent with a thin, oscillating current sheet that is corrugated along the electron flow direction (along the X line), which is a type of electromagnetic drift wave. Near the X line, electron flow is primarily due to a Hall electric field, which diverts ion flow in asymmetric reconnection and accompanies the instability. Importantly, the drift waves appear to drive strong parallel currents which, in turn, generate large-amplitude ( 100 mV/m) E|| in the form of nonlinear waves and structures. These observations suggest that turbulence may be common in asymmetric reconnection, penetrate into the electron diffusion region, and possibly influence the magnetic reconnection process.

Generation and control of polarization-entangled photons from GaAs island quantum dots by an electric field.

PubMed

Ghali, Mohsen; Ohtani, Keita; Ohno, Yuzo; Ohno, Hideo

2012-02-07

Semiconductor quantum dots are potential sources for generating polarization-entangled photons efficiently. The main prerequisite for such generation based on biexciton-exciton cascaded emission is to control the exciton fine-structure splitting. Among various techniques investigated for this purpose, an electric field is a promising means to facilitate the integration into optoelectronic devices. Here we demonstrate the generation of polarization-entangled photons from single GaAs quantum dots by an electric field. In contrast to previous studies, which were limited to In(Ga)As quantum dots, GaAs island quantum dots formed by a thickness fluctuation were used because they exhibit a larger oscillator strength and emit light with a shorter wavelength. A forward voltage was applied to a Schottky diode to control the fine-structure splitting. We observed a decrease and suppression in the fine-structure splitting of the studied single quantum dot with the field, which enabled us to generate polarization-entangled photons with a high fidelity of 0.72 ± 0.05.

Ethylene Removal in Strong Electric Field Formed by Floating Multi-Electrode

NASA Astrophysics Data System (ADS)

Nagasawa, Takeshi

Ethylene gas that contains the acetic acid ester element can be removed by applying the pulse voltage to the floating multi-electrode device. This phenomenon is caused in the weak discharge by the strong electric field between the narrow electrodes. This device is possible in very small electric power (<1.5Wh). When this device was installed in the container for preservation, the following results were obtained: Each removal effect of ethylene gas is 16ppm/35min for bananas 10.8kg, 14ppm/6 hour for 50 apples, and 3.5ppm/30min for 2 melons. However, ethylene gas that doesn't contain the acetic acid ester cannot be removed (ex. ethylene pure gas and Japanese apricot).

Structure of hydrothermal plumes at the Logatchev vent field, 14°45‧N, Mid-Atlantic Ridge: evidence from geochemical and geophysical data

NASA Astrophysics Data System (ADS)

Sudarikov, S. M.; Roumiantsev, A. B.

2000-09-01

In the Seventh cruise of R/V ;Professor Logatchev; anomalies of natural electric field (EF), Eh and pS were discovered using a towed instrument package (RIFT) at 14°45‧N on the MAR (Logatchev hydrothermal field). The anomalous zone (AZ) is situated close (10-35 m) to two low-temperature venting areas of degrading sulphides and a black smoker (Irina-Microsmoke) forming a distinct buoyant plume. Over or close to the main area of high-temperature venting situated to the south-east from the AZ, no EF or Eh anomalies were observed. According to the results of Mir dives the highly mineralised solutions from smoking craters at the main mound mostly form non-buoyant plumes (reverse-plumes). The buoyant plume structure shows the differentiation of the electrical and Eh fields within the plume. Maxima of the EF, Eh and EH2S anomalies were revealed in the lower part (∼15 m) of the plume. The negative redox potential plume coupled with a sulphide anomaly is more localized in comparison with the EF. This observation indicates a distinct change in the composition of buoyant plume water, which may be due to the formation and fallout of early formed Fe sulphide particles soon after venting.

Causal electric charge diffusion and balance functions in relativistic heavy-ion collisions

NASA Astrophysics Data System (ADS)

Kapusta, Joseph I.; Plumberg, Christopher

2018-01-01

We study the propagation and diffusion of electric charge fluctuations in high-energy heavy-ion collisions using the Cattaneo form for the dissipative part of the electric current. As opposed to the ordinary diffusion equation this form limits the speed at which charge can propagate. Including the noise term in the current, which arises uniquely from the fluctuation-dissipation theorem, we calculate the balance functions for charged hadrons in a simple 1+1-dimensional Bjorken hydrodynamical model. Limiting the speed of propagation of charge fluctuations increases the height and reduces the width of these balance functions when plotted versus rapidity. We also estimate the numerical value of the associated diffusion time constant from anti-de Sitter-space/conformal-field theory.

Development of effective power supply using electric double layer capacitor for static magnetic field coils in fusion plasma experiments.

PubMed

Inomoto, M; Abe, K; Yamada, T; Kuwahata, A; Kamio, S; Cao, Q H; Sakumura, M; Suzuki, N; Watanabe, T; Ono, Y

2011-02-01

A cost-effective power supply for static magnetic field coils used in fusion plasma experiments has been developed by application of an electric double layer capacitor (EDLC). A prototype EDLC power supply system was constructed in the form of a series LCR circuit. Coil current of 100 A with flat-top longer than 1 s was successfully supplied to an equilibrium field coil of a fusion plasma experimental apparatus by a single EDLC module with capacitance of 30 F. The present EDLC power supply has revealed sufficient performance for plasma confinement experiments whose discharge duration times are an order of several seconds.

Formation of ZnO at zinc oxidation by near- and supercritical water under the constant electric field

NASA Astrophysics Data System (ADS)

Shishkin, A. V.; Sokol, M. Ya.; Shatrova, A. V.; Fedyaeva, O. N.; Vostrikov, A. A.

2014-12-01

The work has detected an influence of a constant electric field (up to E = 300 kV/m) on the structure of a nanocrystalline layer of zinc oxide, formed on the surface of a planar zinc anode in water under supercritical (673 K and 23 MPa) and near-critical (673 K and 17. 5 MPa) conditions. The effect of an increase of zinc oxidation rate with an increase in E is observed under supercritical conditions and is absent at near-critical ones. Increase in the field strength leads to the formation of a looser structure in the inner part of the zinc oxide layer.

Non-equilibrium behaviour in coacervate-based protocells under electric-field-induced excitation

NASA Astrophysics Data System (ADS)

Yin, Yudan; Niu, Lin; Zhu, Xiaocui; Zhao, Meiping; Zhang, Zexin; Mann, Stephen; Liang, Dehai

2016-02-01

Although numerous strategies are now available to generate rudimentary forms of synthetic cell-like entities, minimal progress has been made in the sustained excitation of artificial protocells under non-equilibrium conditions. Here we demonstrate that the electric field energization of coacervate microdroplets comprising polylysine and short single strands of DNA generates membrane-free protocells with complex, dynamical behaviours. By confining the droplets within a microfluidic channel and applying a range of electric field strengths, we produce protocells that exhibit repetitive cycles of vacuolarization, dynamical fluctuations in size and shape, chaotic growth and fusion, spontaneous ejection and sequestration of matter, directional capture of solute molecules, and pulsed enhancement of enzyme cascade reactions. Our results highlight new opportunities for the study of non-equilibrium phenomena in synthetic protocells, provide a strategy for inducing complex behaviour in electrostatically assembled soft matter microsystems and illustrate how dynamical properties can be activated and sustained in microcompartmentalized media.

Ion mobility sensor system

DOEpatents

Xu, Jun; Watson, David B.; Whitten, William B.

2013-01-22

An ion mobility sensor system including an ion mobility spectrometer and a differential mobility spectrometer coupled to the ion mobility spectrometer. The ion mobility spectrometer has a first chamber having first end and a second end extending along a first direction, and a first electrode system that generates a constant electric field parallel to the first direction. The differential mobility spectrometer includes a second chamber having a third end and a fourth end configured such that a fluid may flow in a second direction from the third end to the fourth end, and a second electrode system that generates an asymmetric electric field within an interior of the second chamber. Additionally, the ion mobility spectrometer and the differential mobility spectrometer form an interface region. Also, the first end and the third end are positioned facing one another so that the constant electric field enters the third end and overlaps the fluid flowing in the second direction.

Non-equilibrium behaviour in coacervate-based protocells under electric-field-induced excitation

PubMed Central

Yin, Yudan; Niu, Lin; Zhu, Xiaocui; Zhao, Meiping; Zhang, Zexin; Mann, Stephen; Liang, Dehai

2016-01-01

Although numerous strategies are now available to generate rudimentary forms of synthetic cell-like entities, minimal progress has been made in the sustained excitation of artificial protocells under non-equilibrium conditions. Here we demonstrate that the electric field energization of coacervate microdroplets comprising polylysine and short single strands of DNA generates membrane-free protocells with complex, dynamical behaviours. By confining the droplets within a microfluidic channel and applying a range of electric field strengths, we produce protocells that exhibit repetitive cycles of vacuolarization, dynamical fluctuations in size and shape, chaotic growth and fusion, spontaneous ejection and sequestration of matter, directional capture of solute molecules, and pulsed enhancement of enzyme cascade reactions. Our results highlight new opportunities for the study of non-equilibrium phenomena in synthetic protocells, provide a strategy for inducing complex behaviour in electrostatically assembled soft matter microsystems and illustrate how dynamical properties can be activated and sustained in microcompartmentalized media. PMID:26876162

In Situ Observations of Electric-Field Induced Nanoparticle Aggregation

NASA Astrophysics Data System (ADS)

Woehl, T. J.; Browning, N. D.; Ristenpart, W. D.

2010-11-01

Nanoparticles have been widely observed to aggregate laterally on electrodes in response to applied electric fields. The mechanism driving this behavior, however, is unclear. Several groups have interpreted the aggregation in terms of electrohydrodynamic or electroosmotic fluid motion, but little corroborating evidence has been presented. Notably, work to date has relied on post situ observations using electron microscopy. Here we present a fluorescence microscopy technique to track the dynamics of nanoparticle aggregation in situ. Fluorescent 20-nm polystyrene nanoparticles are observed to form optically visible aggregates in response to an applied AC field. Although single particle resolution is lost, the existence of aggregates on the electrode surface is marked by growing clusters of increasingly bright intensity. We present a systematic investigation of the effects of applied potential and frequency on the aggregation rate, and we interpret the behavior in terms of a mechanism based on electrically induced convective flow.

Controlled Electrochemical Deformation of Liquid-Phase Gallium.

PubMed

Chrimes, Adam F; Berean, Kyle J; Mitchell, Arnan; Rosengarten, Gary; Kalantar-zadeh, Kourosh

2016-02-17

Pure gallium is a soft metal with a low temperature melting point of 29.8 °C. This low melting temperature can potentially be employed for creating optical components with changeable configurations on demand by manipulating gallium in its liquid state. Gallium is a smooth and highly reflective metal that can be readily maneuvered using electric fields. These features allow gallium to be used as a reconfigurable optical reflector. This work demonstrates the use of gallium for creating reconfigurable optical reflectors manipulated through the use of electric fields when gallium is in a liquid state. The use of gallium allows the formed structures to be frozen and preserved as long as the temperature of the metal remains below its melting temperature. The lens can be readily reshaped by raising the temperature above the melting point and reapplying an electric field to produce a different curvature of the gallium reflector.

The control of ultrasonic transmission by the metamaterials structure of electrorheological fluid and metal foam

NASA Astrophysics Data System (ADS)

Li, Linlin; Wang, Mingzhong; Wang, Jiahui; Zhao, Xiaopeng

2017-11-01

A metamaterial structure formed by foamed metal and starch and oil-based electrorheological (ER) fluid is designed in this paper. Experiments show that the metamaterial structure exhibits a regulation effect on the amplitude and phase of the transmitted waves of 35-80 kHz ultra-wideband ultrasonic waves in water. With the increase of the electric field, the transmission amplitude and phase of the ultrasonic wave increases, whereas the control ability of the same gradient electric field decreases. The amplitude of the transmission controlled by the metamaterial structure and electric field increases at first, and then decreases with the increase in volume fraction of the ER fluid. Thus, it is thought that the interaction between the microstructure produced by the rheological properties of the ER fluid and the porous foam metal affects the propagation of the acoustic wave.

Study of diffusion of wave packets in a square lattice under external fields along the discrete nonlinear Schrödinger equation

NASA Astrophysics Data System (ADS)

de Brito, P. E.; Nazareno, H. N.

2012-09-01

The object of the present work is to analyze the effect of nonlinearity on wave packet propagation in a square lattice subject to a magnetic and an electric field in the Hall configuration, by using the Discrete Nonlinear Schrödinger Equation (DNLSE). In previous works we have shown that without the nonlinear term, the presence of the magnetic field induces the formation of vortices that remain stationary, while a wave packet is introduced in the system. As for the effect of an applied electric field, it was shown that the vortices propagate in a direction perpendicular to the electric field, similar behavior as presented in the classical treatment, we provide a quantum mechanics explanation for that. We have performed the calculations considering first the action of the magnetic field as well as the nonlinearity. The results indicate that for low values of the nonlinear parameter U the vortices remain stationary while preserving the form. For greater values of the parameter the picture gets distorted, the more so, the greater the nonlinearity. As for the inclusion of the electric field, we note that for small U, the wave packet propagates perpendicular to the applied field, until for greater values of U the wave gets partially localized in a definite region of the lattice. That is, for strong nonlinearity the wave packet gets partially trapped, while the tail of it can propagate through the lattice. Note that this tail propagation is responsible for the over-diffusion for long times of the wave packet under the action of an electric field. We have produced short films that show clearly the time evolution of the wave packet, which can add to the understanding of the dynamics.

F-centers mechanism of long-term relaxation in lead zirconate-titanate based piezoelectric ceramics. 2. After-field relaxation

NASA Astrophysics Data System (ADS)

Ishchuk, V. M.; Kuzenko, D. V.

2016-08-01

The paper presents results of experimental study of the dielectric constant relaxation during aging process in Pb(Zr,Ti)O3 based solid solutions (PZT) after action of external DC electric field. The said process is a long-term one and is described by the logarithmic function of time. Reversible and nonreversible relaxation process takes place depending on the field intensity. The relaxation rate depends on the field strength also, and the said dependence has nonlinear and nonmonotonic form, if external field leads to domain disordering. The oxygen vacancies-based model for description of the long-term relaxation processes is suggested. The model takes into account the oxygen vacancies on the sample's surface ends, their conversion into F+- and F0-centers under external effects and subsequent relaxation of these centers into the simple oxygen vacancies after the action termination. F-centers formation leads to the violation of the original sample's electroneutrality, and generate intrinsic DC electric field into the sample. Relaxation of F-centers is accompanied by the reduction of the electric field, induced by them, and relaxation of the dielectric constant, as consequent effect.

Improvements in Ionized Cluster-Beam Deposition

NASA Technical Reports Server (NTRS)

Fitzgerald, D. J.; Compton, L. E.; Pawlik, E. V.

1986-01-01

Lower temperatures result in higher purity and fewer equipment problems. In cluster-beam deposition, clusters of atoms formed by adiabatic expansion nozzle and with proper nozzle design, expanding vapor cools sufficiently to become supersaturated and form clusters of material deposited. Clusters are ionized and accelerated in electric field and then impacted on substrate where films form. Improved cluster-beam technique useful for deposition of refractory metals.

Voltage gradients in solar array cavities as possible breakdown sites in spacecraft-charging-induced discharges

NASA Technical Reports Server (NTRS)

Stevens, N. J.; Mills, H. E.; Orange, L.

1981-01-01

A possible explanation for environmentally-induced discharges on geosynchronous satellites exists in the electric fields formed in the cavities between solar cells - the small gaps formed by the cover slides, solar cells, metallic interconnects and insulating substrate. When exposed to a substorm environment, the cover slides become less negatively charged than the spacecraft ground. If the resultant electric field becomes large enough, then the interconnect could emit electrons (probably by field emission) which could be accelerated to space by the positive voltage on the covers. An experimental study was conducted using a small solar array segment in which the interconnect potential was controlled by a power supply while the cover slides were irradiated by monoenergetic electrons. It was found that discharges could be triggered when the interconnect potential became at least 500 volts negative with respect to the cover slides. Analytical modeling of satellites exposed to substorm environments indicates that such gradients are possible. Therefore, it appears that this trigger mechanism for discharges is possible.

Split Octonion Reformulation for Electromagnetic Chiral Media of Massive Dyons

NASA Astrophysics Data System (ADS)

Chanyal, B. C.

2017-12-01

In an explicit, unified, and covariant formulation of an octonion algebra, we study and generalize the electromagnetic chiral fields equations of massive dyons with the split octonionic representation. Starting with 2×2 Zorn’s vector matrix realization of split-octonion and its dual Euclidean spaces, we represent the unified structure of split octonionic electric and magnetic induction vectors for chiral media. As such, in present paper, we describe the chiral parameter and pairing constants in terms of split octonionic matrix representation of Drude-Born-Fedorov constitutive relations. We have expressed a split octonionic electromagnetic field vector for chiral media, which exhibits the unified field structure of electric and magnetic chiral fields of dyons. The beauty of split octonionic representation of Zorn vector matrix realization is that, the every scalar and vector components have its own meaning in the generalized chiral electromagnetism of dyons. Correspondingly, we obtained the alternative form of generalized Proca-Maxwell’s equations of massive dyons in chiral media. Furthermore, the continuity equations, Poynting theorem and wave propagation for generalized electromagnetic fields of chiral media of massive dyons are established by split octonionic form of Zorn vector matrix algebra.

Subcellular Biological Effects of Nanosecond Pulsed Electric Fields

NASA Astrophysics Data System (ADS)

Kolb, Juergen F.; Stacey, Michael

Membranes of biological cells can be charged by exposure to pulsed electric fields. After the potential difference across the barrier reaches critical values on the order of 1 V, pores will form. For moderate pulse parameters of duration and amplitude, the effect is limited to the outer cell membrane. With the exposure to nanosecond pulses of several tens of kilovolts per centimeter, a similar effect is also expected for subcellular membranes and structures. Cells will respond to the disruption by different biochemical processes. This offers possibilities for the development of novel medical therapies, the manipulation of cells and microbiological decontamination.

Microwave Magnetochiral Dichroism in the Chiral-Lattice Magnet Cu2OSeO3

NASA Astrophysics Data System (ADS)

Okamura, Y.; Kagawa, F.; Seki, S.; Kubota, M.; Kawasaki, M.; Tokura, Y.

2015-05-01

Through broadband microwave spectroscopy in Faraday geometry, we observe distinct absorption spectra accompanying magnetoelectric (ME) resonance for oppositely propagating microwaves, i.e., directional dichroism, in the multiferroic chiral-lattice magnet Cu2OSeO3. The magnitude of the directional dichroism critically depends on the magnetic-field direction. Such behavior is well accounted for by considering the relative direction of the oscillating electric polarizations induced via the ME effect with respect to microwave electric fields. Directional dichroism in a system with an arbitrary form of ME coupling can be also discussed in the same manner.

Electromagnetic induction pump for pumping liquid metals and other conductive liquids

DOEpatents

Smither, R.K.

1993-05-11

An electromagnetic induction pump is described in which an electrically conductive liquid is made to flow by means of a force created by interaction of a permanent magnetic field and a DC current. The pump achieves high efficiency through combination of: powerful permanent magnet materials which provide a high strength field that is uniform and constant; steel tubing formed into a coil which is constructed to carry conducting liquids with minimal electrical resistance and heat; and application of a voltage to induce a DC current which continuously produces a force in the direction of the desired flow.

Electromagnetic induction pump for pumping liquid metals and other conductive liquids

DOEpatents

Smither, Robert K.

1993-01-01

An electromagnetic induction pump in which an electrically conductive liquid is made to flow by means of a force created by interaction of a permanent magnetic field and a DC current. The pump achieves high efficiency through combination of: powerful permanent magnet materials which provide a high strength field that is uniform and constant; steel tubing formed into a coil which is constructed to carry conducting liquids with minimal electrical resistance and heat; and application of a voltage to induce a DC current which continuously produces a force in the direction of the desired flow.

Membraneless seawater desalination

DOEpatents

Crooks, Richard A.; Knust, Kyle N.; Perdue, Robbyn K.

2018-04-03

Disclosed are microfluidic devices and systems for the desalination of water. The devices and systems can include an electrode configured to generate an electric field gradient in proximity to an intersection formed by the divergence of two microfluidic channels from an inlet channel. Under an applied bias and in the presence of a pressure driven flow of saltwater, the electric field gradient can preferentially direct ions in saltwater into one of the diverging microfluidic channels, while desalted water flows into second diverging channel. Also provided are methods of using the devices and systems described herein to decrease the salinity of water.

Transverse kinetics of a charged drop in an external electric field

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

Bondarenko, S.; Komoshvili, K.

2016-01-22

We investigate a non-equilibrium behavior of a small, dense and charged drop in the transverse plane. A collective motion of the drop’s particles with constant entropy is described. Namely, we solve Vlasov’s equation with non-isotropic initial conditions. Thereby a non-equilibrium distribution function of the process of the droplet evolution in the transverse plane is calculated. An external electric field is included in the initial conditions of the equation that affects on the form of the obtained solution. Applicability of the results to the description of initial states of quark-gluon plasma is also discussed.

Ultra Thin Poly-Si Nanosheet Junctionless Field-Effect Transistor with Nickel Silicide Contact

PubMed Central

Lin, Yu-Ru; Tsai, Wan-Ting; Wu, Yung-Chun; Lin, Yu-Hsien

2017-01-01

This study demonstrated an ultra thin poly-Si junctionless nanosheet field-effect transistor (JL NS-FET) with nickel silicide contact. For the nickel silicide film, two-step annealing and a Ti capping layer were adopted to form an ultra thin uniform nickel silicide film with low sheet resistance (Rs). The JL NS-FET with nickel silicide contact exhibited favorable electrical properties, including a high driving current (>107A), subthreshold slope (186 mV/dec.), and low parasitic resistance. In addition, this study compared the electrical characteristics of JL NS-FETs with and without nickel silicide contact. PMID:29112139

Ultra Thin Poly-Si Nanosheet Junctionless Field-Effect Transistor with Nickel Silicide Contact.

PubMed

Lin, Yu-Ru; Tsai, Wan-Ting; Wu, Yung-Chun; Lin, Yu-Hsien

2017-11-07

This study demonstrated an ultra thin poly-Si junctionless nanosheet field-effect transistor (JL NS-FET) with nickel silicide contact. For the nickel silicide film, two-step annealing and a Ti capping layer were adopted to form an ultra thin uniform nickel silicide film with low sheet resistance (Rs). The JL NS-FET with nickel silicide contact exhibited favorable electrical properties, including a high driving current (>10⁷A), subthreshold slope (186 mV/dec.), and low parasitic resistance. In addition, this study compared the electrical characteristics of JL NS-FETs with and without nickel silicide contact.

Effect of the electric field on buckled and puckered arsenene

NASA Astrophysics Data System (ADS)

Chavez, Victor Hugo; Fernandez-Escamilla, Hector Noe; Martínez-Guerra, Edgar

With the emergence of new 2D materials, more recently phosphorene, arsenene appears as a new candidate to be explored for electronic devices. We have studied the stability of arsenene pristine and the effect of a transversal electric field on its electronic properties. The calculations were performed using the SIESTA code, with the GGA exchange-correlation functional in the PBE form. We have used numerical atomic orbitals as the basis set for the valence wavefunctions employing a double ζ-polarized basis. We use the Perdew-Becke pseudopotential for an As atom that includes the scalar-relativistic effect and Troullier-Martins parametrization. We adopt the Monkhorst-Pack scheme for k-point sampling of Brillouin zone integrations with 25 ×25 ×1 and 25 ×25 ×1 for the buckled/planar and puckered systems, respectively. We found that buckled and puckered arsenenes are stable and posses indirect gap. The effect of the electric field on the electronic structure of the buckled arsenene is the modulation of indirect to direct gap, while in puckered arsenene the gap linearly decreases as electric field is increased. This research was supported by Consejo Nacional de Ciencia y Tecnología (Conacyt) under Grant No. 43830-F.

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.

Application of AWE Along with a Combined FEM/MoM Technique to Compute RCS of a Cavity-Backed Aperture in an Infinite Ground Plane Over a Frequency Range

NASA Technical Reports Server (NTRS)

Reddy, C.J.; Deshpande, M.D.

1997-01-01

A hybrid Finite Element Method (FEM)/Method of Moments (MoM) technique in conjunction with the Asymptotic Waveform Evaluation (AWE) technique is applied to obtain radar cross section (RCS) of a cavity-backed aperture in an infinite ground plane over a frequency range. The hybrid FEM/MoM technique when applied to the cavity-backed aperture results in an integro-differential equation with electric field as the unknown variable, the electric field obtained from the solution of the integro-differential equation is expanded in Taylor series. The coefficients of the Taylor series are obtained using the frequency derivatives of the integro-differential equation formed by the hybrid FEM/MoM technique. The series is then matched via the Pade approximation to a rational polynomial, which can be used to extrapolate the electric field over a frequency range. The RCS of the cavity-backed aperture is calculated using the electric field at different frequencies. Numerical results for a rectangular cavity, a circular cavity, and a material filled cavity are presented over a frequency range. Good agreement between AWE and the exact solution over the frequency range is obtained.

Long-wave analysis and control of the viscous Rayleigh-Taylor instability with electric fields

NASA Astrophysics Data System (ADS)

Cimpeanu, Radu; Anderson, Thomas; Petropoulos, Peter; Papageorgiou, Demetrios

2016-11-01

We investigate the electrostatic stabilization of a viscous thin film wetting the underside of a solid surface in the presence of a horizontally acting electric field. The competition between gravity, surface tension and the nonlocal effect of the applied electric field is captured analytically in the form of a nonlinear evolution equation. A semi-spectral solution strategy is employed to resolve the dynamics of the resulting partial differential equation. Furthermore, we conduct direct numerical simulations (DNS) of the Navier-Stokes equations and assess the accuracy of the obtained solutions when varying the electric field strength from zero up to the point when complete stabilization at the target finite wavelengths occurs. We employ DNS to examine the limitations of the asymptotically derived behavior in the context of increasing liquid film heights, with agreement found to be excellent even beyond the target lengthscales. Regimes in which the thin film assumption is no longer valid and droplet pinch-off occurs are then analyzed. Finally, the asymptotic and computational approaches are used in conjunction to identify efficient active control mechanisms allowing the manipulation of the fluid interface in light of engineering applications at small scales, such as mixing.

Modulation of the electronic property of phosphorene by wrinkle and vertical electric field

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

Li, Yan; Wei, Zhongming, E-mail: zmwei@semi.ac.cn; Li, Jingbo, E-mail: jbli@semi.ac.cn

2015-09-14

The electronic properties of wrinkled phosphorene and its response to charge injection and external vertical electric field have been studied using first-principles calculations. It is found that small-size wrinkle systems have lower energy than wrinkle-free monolayer, suggesting that free-standing phosphorene spontaneously forms small protrusion on its nanosheet. The ratio of wrinkle height to curvature radius increases with enlarging height, indicating a promotion of field enhancement factor. Furthermore, the injected charges mostly distribute at peak and valley. Direct-to-indirect band-gap transition has been found for zigzag wrinkle with height of 14.81 Å. The band gaps of wrinkled nanosheets decrease almost linearly with increasingmore » field, which is caused by charge separation of valence band maximum and conduction band minimum.« less

Charge control experiments on a CH-53E helicopter in a dusty environment

NASA Technical Reports Server (NTRS)

Moore, C. B.; Jones, J. J.; Hunyady, S. J.

1991-01-01

Charge control tests were carried out on a ground based, Marine Corps helicopter to determine if control of the electric fields acting on the engine exhaust gases could be used to reduce the electrification of the helicopter when it operated in a dusty atmosphere. The test aircraft was flown to a dusty, unpaved area and was then isolated electrically from the earth. When the helicopter engines were operated at ground idle with the rotor locked, the isolated aircraft charged positively, as had been observed previously. However, when the rotor brake was released and the turning rotor created a downdraft that raised dust clouds, the aircraft always became charged more positively, to potentials ranging form +30 to +45 kV. The dust clouds raised by the rotor downwash invariably carried negative space charges with concentrations of up to -100 nC/cu m and caused surface electric fields with strengths of up to 10 kV/m immediately down wind of the aircraft. The natural charging of the helicopter operating in these dust clouds was successfully opposed by control of the electric fields acting on the hot, electrically conductive exhaust gases. The control was achieved by placing electrostatic shield around the exhausts.

Method for correction of measured polarization angles from motional Stark effect spectroscopy for the effects of electric fields

DOE PAGES

Luce, T. C.; Petty, C. C.; Meyer, W. H.; ...

2016-11-02

An approximate method to correct the motional Stark effect (MSE) spectroscopy for the effects of intrinsic plasma electric fields has been developed. The motivation for using an approximate method is to incorporate electric field effects for between-pulse or real-time analysis of the current density or safety factor profile. The toroidal velocity term in the momentum balance equation is normally the dominant contribution to the electric field orthogonal to the flux surface over most of the plasma. When this approximation is valid, the correction to the MSE data can be included in a form like that used when electric field effectsmore » are neglected. This allows measurements of the toroidal velocity to be integrated into the interpretation of the MSE polarization angles without changing how the data is treated in existing codes. In some cases, such as the DIII-D system, the correction is especially simple, due to the details of the neutral beam and MSE viewing geometry. The correction method is compared using DIII-D data in a variety of plasma conditions to analysis that assumes no radial electric field is present and to analysis that uses the standard correction method, which involves significant human intervention for profile fitting. The comparison shows that the new correction method is close to the standard one, and in all cases appears to offer a better result than use of the uncorrected data. Lastly, the method has been integrated into the standard DIII-D equilibrium reconstruction code in use for analysis between plasma pulses and is sufficiently fast that it will be implemented in real-time equilibrium analysis for control applications.« less

Automated seed manipulation and planting

NASA Technical Reports Server (NTRS)

Garcia, Ray; Herrera, Javier; Holcomb, Scott; Kelly, Paul; Myers, Scott; Rosendo, Manny; Sivitz, Herbert; Wolsefer, Dave

1988-01-01

Activities for the Fall Semester, 1987 focused on investigating the mechanical/electrical properties of wheat seeds and forming various Seed Planting System (SPS) concepts based on those properties. The Electrical Division of the design group was formed to devise an SPS using electrostatic charge fields for seeding operations. Experiments concerning seed separation using electrical induction (rearranging of the charges within the seed) were conducted with promising results. The seeds, when exposed to the high voltage and low current field produced by a Van de Graff generator, were observed to move back and forth between two electrodes. An SPS concept has been developed based on this phenomena, and will be developed throughout the Spring Semester, 1988. The Mechanical Division centered on SPS concepts involving valves, pumps, and fluids to separate and deliver seeds. An SPS idea utilizing the pressure difference caused by air as it rushes out of holes drilled in the wall of a closed container has been formulated and will be considered for future development. Also, a system of seed separation and delivery employing a combination of centrifugal force, friction, and air flow was considered.

A unified engineering model of the first stroke in downward negative lightning

NASA Astrophysics Data System (ADS)

Nag, Amitabh; Rakov, Vladimir A.

2016-03-01

Each stroke in a negative cloud-to-ground lightning flash is composed of downward leader and upward return stroke processes, which are usually modeled individually. The first stroke leader is stepped and starts with preliminary breakdown (PB) which is often viewed as a separate process. We present the first unified engineering model for computing the electric field produced by a sequence of PB, stepped leader, and return stroke processes, serving to transport negative charge to ground. We assume that a negatively charged channel extends downward in a stepped fashion during both the PB and leader stages. Each step involves a current wave that propagates upward along the newly formed channel section. Once the leader attaches to ground, an upward propagating return stroke neutralizes the charge deposited along the channel. Model-predicted electric fields are in reasonably good agreement with simultaneous measurements at both near (hundreds of meters, electrostatic field component is dominant) and far (tens of kilometers, radiation field component is dominant) distances from the lightning channel. Relations between the features of computed electric field waveforms and model input parameters are examined. It appears that peak currents associated with PB pulses are similar to return stroke peak currents, and the observed variation of electric radiation field peaks produced by leader steps at different heights above ground is influenced by the ground corona space charge.

Formation of electron energy spectra during magnetic reconnection in laser-produced plasma

NASA Astrophysics Data System (ADS)

Huang, Kai; Lu, Quanming; Huang, Can; Dong, Quanli; Wang, Huanyu; Fan, Feibin; Sheng, Zhengming; Wang, Shui; Zhang, Jie

2017-10-01

Energetic electron spectra formed during magnetic reconnection between two laser-produced plasma bubbles are investigated by the use of two-dimensional particle-in-cell simulations. It is found that the evolution of such an interaction between the two plasma bubbles can be separated into two distinct stages: squeezing and reconnection stages. In the squeezing stage, when the two plasma bubbles expand quickly and collide with each other, the magnetic field in the inflow region is greatly enhanced. In the second stage, a thin current sheet is formed between the two plasma bubbles, and then, magnetic reconnection occurs therein. During the squeezing stage, electrons are heated in the perpendicular direction by betatron acceleration due to the enhancement of the magnetic field around the plasma bubbles. Meanwhile, non-thermal electrons are generated by the Fermi mechanism when these electrons bounce between the two plasma bubbles approaching quickly and get accelerated mainly by the convective electric field associated with the plasma bubbles. During the reconnection stage, electrons get further accelerated mainly by the reconnection electric field in the vicinity of the X line. When the expanding speed of the plasma bubbles is sufficiently large, the formed electron energy spectra have a kappa distribution, where the lower energy part satisfies a Maxwellian function and the higher energy part is a power-law distribution. Moreover, the increase in the expanding speed will result in the hardening of formed power-law spectra in both the squeezing and reconnection stages.

Water-processed carbon nanotube/graphene hybrids with enhanced field emission properties

NASA Astrophysics Data System (ADS)

Song, Meng; Xu, Peng; Song, Yenan; Wang, Xu; Li, Zhenhua; Shang, Xuefu; Wu, Huizhen; Zhao, Pei; Wang, Miao

2015-09-01

Integrating carbon nanotubes (CNTs) and graphene into hybrid structures provides a novel approach to three dimensional (3D) materials with advantageous properties. Here we present a water-processing method to create integrated CNT/graphene hybrids and test their field emission properties. With an optimized mass ratio of CNTs to graphene, the hybrid shows a significantly enhanced field emission performance, such as turn-on electric field of 0.79 V/μm, threshold electric field of 1.05 V/μm, maximum current density of 0.1 mA/cm2, and field enhancement factor of ˜1.3 × 104. The optimized mass ratio for field emission emphasizes the importance of both CNTs and graphene in the hybrid. We also hypothesize a possible mechanism for this enhanced field emission performance from the CNT/graphene hybrid. During the solution treatment, graphene oxide behaves as surfactant sheets for CNTs to form a well dispersed solution, which leads to a better organized 3D structure with more conducting channels for electron transport.

Impact of local electrostatic field rearrangement on field ionization

NASA Astrophysics Data System (ADS)

Katnagallu, Shyam; Dagan, Michal; Parviainen, Stefan; Nematollahi, Ali; Grabowski, Blazej; Bagot, Paul A. J.; Rolland, Nicolas; Neugebauer, Jörg; Raabe, Dierk; Vurpillot, François; Moody, Michael P.; Gault, Baptiste

2018-03-01

Field ion microscopy allows for direct imaging of surfaces with true atomic resolution. The high charge density distribution on the surface generates an intense electric field that can induce ionization of gas atoms. We investigate the dynamic nature of the charge and the consequent electrostatic field redistribution following the departure of atoms initially constituting the surface in the form of an ion, a process known as field evaporation. We report on a new algorithm for image processing and tracking of individual atoms on the specimen surface enabling quantitative assessment of shifts in the imaged atomic positions. By combining experimental investigations with molecular dynamics simulations, which include the full electric charge, we confirm that change is directly associated with the rearrangement of the electrostatic field that modifies the imaging gas ionization zone. We derive important considerations for future developments of data reconstruction in 3D field ion microscopy, in particular for precise quantification of lattice strains and characterization of crystalline defects at the atomic scale.

Differential form representation of stochastic electromagnetic fields

NASA Astrophysics Data System (ADS)

Haider, Michael; Russer, Johannes A.

2017-09-01

In this work, we revisit the theory of stochastic electromagnetic fields using exterior differential forms. We present a short overview as well as a brief introduction to the application of differential forms in electromagnetic theory. Within the framework of exterior calculus we derive equations for the second order moments, describing stochastic electromagnetic fields. Since the resulting objects are continuous quantities in space, a discretization scheme based on the Method of Moments (MoM) is introduced for numerical treatment. The MoM is applied in such a way, that the notation of exterior calculus is maintained while we still arrive at the same set of algebraic equations as obtained for the case of formulating the theory using the traditional notation of vector calculus. We conclude with an analytic calculation of the radiated electric field of two Hertzian dipole, excited by uncorrelated random currents.

Tortuosity of lightning return stroke channels

NASA Technical Reports Server (NTRS)

Levine, D. M.; Gilson, B.

1984-01-01

Data obtained from photographs of lightning are presented on the tortuosity of return stroke channels. The data were obtained by making piecewise linear fits to the channels, and recording the cartesian coordinates of the ends of each linear segment. The mean change between ends of the segments was nearly zero in the horizontal direction and was about eight meters in the vertical direction. Histograms of these changes are presented. These data were used to create model lightning channels and to predict the electric fields radiated during return strokes. This was done using a computer generated random walk in which linear segments were placed end-to-end to form a piecewise linear representation of the channel. The computer selected random numbers for the ends of the segments assuming a normal distribution with the measured statistics. Once the channels were simulated, the electric fields radiated during a return stroke were predicted using a transmission line model on each segment. It was found that realistic channels are obtained with this procedure, but only if the model includes two scales of tortuosity: fine scale irregularities corresponding to the local channel tortuosity which are superimposed on large scale horizontal drifts. The two scales of tortuosity are also necessary to obtain agreement between the electric fields computed mathematically from the simulated channels and the electric fields radiated from real return strokes. Without large scale drifts, the computed electric fields do not have the undulations characteristics of the data.

Analysis of the axisymmetric indentation of a semi-infinite piezoelectric material: The evaluation of the contact stiffness and the effective piezoelectric constant

NASA Astrophysics Data System (ADS)

Yang, Fuqian

2008-04-01

A general solution of the axisymmetric indentation is obtained in the closed form for a semi-infinite, transverse isotropic piezoelectric material by a rigid-conducting indenter of arbitrary-axisymmetric profile. Explicit relationships are derived for dependences of the indentation depth and the indentation-induced charge on indentation force and applied electrical potential. Simple formulas are obtained for contact stiffness and effective piezoelectric constant, which can be used in indentation test and piezoresponse force microscopy to analyze the elastic and piezoelectric responses of piezoelectric materials. Depending on the direction of electric field (the potential difference), the electric field can either increase or suppress indentation deformation. The corresponding results are given for cylindrical, conical, and paraboloidal indenters.

Nanoscale oxidation and complex oxide growth on single crystal iron surfaces and external electric field effects.

PubMed

Jeon, Byoungseon; Van Overmeere, Quentin; van Duin, Adri C T; Ramanathan, Shriram

2013-02-14

Oxidation of iron surfaces and oxide growth mechanisms have been studied using reactive molecular dynamics. Oxide growth kinetics on Fe(100), (110), and (111) surface orientations has been investigated at various temperatures and/or an external electric field. The oxide growth kinetics decreases in the order of (110), (111), and (100) surfaces at 300 K over 1 ns timescale while higher temperature increases the oxidation rate. The oxidation rate shows a transition after an initial high rate, implying that the oxide formation mechanism evolves, with iron cation re-ordering. In early stages of surface oxide growth, oxygen transport through iron interstitial sites is dominant, yielding non-stoichiometric wüstite characteristics. The dominant oxygen inward transport decreases as the oxide thickens, evolving into more stoichiometric oxide phases such as wüstite or hematite. This also suggests that cation outward transport increases correspondingly. In addition to oxidation kinetics simulations, formed oxide layers have been relaxed in the range of 600-1500 K to investigate diffusion characteristics, fitting these results into an Arrhenius relation. The activation energy of oxygen diffusion in oxide layers formed on Fe(100), (110), and (111) surfaces was estimated to be 0.32, 0.26, and 0.28 eV, respectively. Comparison between our modeling results and literature data is then discussed. An external electric field (10 MV cm(-1)) facilitates initial oxidation kinetics by promoting oxygen transport through iron lattice interstitial sites, but reaches self-limiting thickness, showing that similar oxide formation stages are maintained when cation transport increases. The effect of the external electric field on iron oxide structure, composition, and oxide activation energy is found to be minimal, whereas cation outward migration is slightly promoted.

Miniaturized two-stack Blumlein pulser with a variable repetition-rate for non-thermal irreversible-electroporation experiments

NASA Astrophysics Data System (ADS)

Min, Sun-Hong; Kwon, Ohjoon; Sattorov, Matlabjon; Baek, In-Keun; Kim, Seontae; Jeong, Jin-Young; Hong, Dongpyo; Park, Seunghyuk; Park, Gun-Sik

2017-01-01

Non-thermal irreversible electroporation (NTIRE) to avoid thermal damage to cells during intense DC ns pulsed electric fields (nsPEFs) is a recent modality for medical applications. This mechanism, related to bioelectrical dynamics of the cell, is linked to the effect of a DC electric field and a threshold effect with an electrically stimulated membrane for the charge distribution in the cell. To create the NTIRE condition, the pulse width of the nsPEF should be shorter than the charging time constant of the membrane related to the cell radius, membrane capacitance, cytoplasm resistivity, and medium resistivity. It is necessary to design and fabricate a very intense nanosecond DC electric field pulser that is capable of producing voltages up to the level of 100 kV/cm with an artificial pulse width (˜ns) with controllable repetition rates. Many devices to generate intense DC nsPEF using various pulse-forming line technologies have been introduced thus far. However, the previous Blumlein pulse-generating devices are clearly inefficient due to the energy loss between the input voltage and the output voltage. An improved two-stage stacked Blumlein pulse-forming line can overcome this limitation and decrease the energy loss from a DC power supply. A metal oxide silicon field-effect transistor switch with a fast rise and fall time would enable a high repetition rate (max. 100 kHz) and good endurance against very high voltages (DC ˜ 30 kV). The load is designed to match the sample for exposure to cell suspensions consisting of a 200 Ω resistor matched with a Blumlein circuit and two electrodes without the characteristic RC time effect of the circuit (capacitance =0.174 pF).

Dynamic characteristics of electric discharge in liquid under ultrasonic cavitation

NASA Astrophysics Data System (ADS)

Bulychev, N. A.; Kazaryan, M. A.; Averyushkin, A. S.; Kirichenko, M. N.; Zakharyan, Robert; Chernov, A. A.

2018-04-01

The characteristics of electrical discharges in liquid media under the influence of intense ultrasonic vibrations are investigated and the difference in dynamic characteristics of discharges before cavitation and after cavitation begins. The experiments carried out during this work made it possible to establish that in a liquid in an intense ultrasonic field above the cavitation threshold there exists a special form of an electric discharge characterized by volumetric luminescence in the entire space between the electrodes and the current-voltage characteristic inherent in an anomalous glow discharge in a gas.

A Nontoxic Barlow's Wheel

NASA Astrophysics Data System (ADS)

Daffron, John A.; Greenslade, Thomas B.

2015-01-01

Barlow's wheel has been a favorite demonstration since its invention by Peter Barlow (1776-1862) in 1822.1 In the form shown in Fig. 1, it represents the first electric motor. The interaction between the electric current passing from the axle of the wheel to the rim and the magnetic field produced by the U-magnet produces a torque that turns the wheel. The original device used mercury to provide electrical contact to the rim, and the dangers involved with the use of this heavy metal have caused the apparatus to disappear from the lecture hall.

Theoretical Investigations of Dielectric Breakdown in CO2: Implications for Atmospheric Discharges on Mars (and Venus)

NASA Astrophysics Data System (ADS)

Riousset, J. A.

2017-12-01

The detection of an atmospheric discharge in the Martian atmosphere by Ruf et al. [GRL, 36, L13202, 2009] supports the idea of a Martian atmospheric electric circuit [Farrell and Desch, JGR, 106, E4, 2001]. However, the lack of subsequent detection of similar events raises the question of the conditions of their initiation, and the existence of Martian lightning remains a controversial question. On Earth, atmospheric electricity manifests itself in the form of glow, corona, streamer, and leader discharges observed as Saint Elmo's fire, sprites, lightning and jets discharges, and other Transient Luminous Events (TLEs). All of these are dielectric breakdown governed by different physics. Their initiation is associated with the crossing of specific electric field thresholds: relativistic runaway, streamer propagation, conventional breakdown, or thermal runaway thresholds, some better understood than others. For example, the initiation of a lightning discharge is known to occur when the local electric field exceeds a value similar to relativistic runaway field, but the exact threshold, as well as the physical mechanisms at work, remain unclear to date. Scaling laws for electric fields (and other quantities) have been established by Pasko et al. [GRL, 25(12), 2123-2126, 1998] and Pasko [NATO Sci. Series, Springer, 253-311, 2006]. In this work, we develop profiles for initiation criteria in air and in other atmospheric environments. We further calculate their associated scaling laws to determine the ability to trigger lightning flashes and TLEs on Mars. This lets us predict the likelihood of electrical discharges and calculate the expected electric field conditions, under which discharges could be observed. We develop the analogy between Earth sand storm [Nicoll et al., Env. Res. Lett., 6, 014001, 2001] and Martian dust storms [Melnik and Parrot, JGR, 103(A12), 1998] to investigate the charge structure and resulting electric fields necessary to initiate dielectric breakdown in the Martian atmosphere. Initiation of electric discharges will be susceptible to local pressure, density, atmospheric composition, and charge structure, and will impact charge moment variations detectable by remote sensing.

Atmospheric electrical detection of organized convection.

PubMed

Markson, R

1975-06-20

Relatively simple atmospheric electrical instrumentation carried on a small aircraft constitutes a flexible and sensitive system for detecting organized convection. Data can be obtained close to the sea surface, and low-velocity flight enhances the spatial resolution. With a slow-flying airplane or powered glider, it may be possible to trace the circulation of individual convection cells and to investigate the trajectory of air which forms cumulus clouds, one of the major unsolved problems in tropical meteorology. Since space charge near the ocean surface was found on some days to be organized on a horizontal scale equivalent to the cumulus cloud scale, this suggests that some of the air which forms maritime cumulus clouds may come from within a few meters of the ocean and that atmospheric electrical instrumentation may have the potential for tracing air from the sea surface to the clouds. Although the atmospheric electrical instrumentation technique described here cannot be used for direct measurement of air velocity, it may be possible to develop model that can be used to calculate air velocities from electric field data. Even though with the technique described here it is not possible to make direct measurements of wind velocity, airborne electric field records can provide useful information about convection by delineating patterns in the wind field and structural features of thermals (rising bodies of relatively warm air) and by making possible the remote detection of thermals (29). Future plans include attempting to trace interfaces between adjacent roll vortices from the sea surface through the depth of the mixed layer (i) by flying the aircraft parallel to the wind so as to nullify the horizontal electric field (measured between wing-tip probes) while ascending and descending along the interface between adjacent roll vortices and (ii) by measuring vertical and horizontal potential gradient variations at different flight levels (30). The sensitivity of atmospheric electrical instrumentation to the top of the mixed layer and structure within it can be used to explore another important problem in boundary layer convection-why convective cloud cover and oceanic rainfall are greater at night than during the day(31). Workers in atmospheric electricity have long recognized that their domain is strongly controlled by turbulence in the lower atmosphere, and many have believed that the most effective use of atmospheric electrical techniques to assist meteorological research would be in studying exchange processes. Reiter [see (8)] effectively extended atmospheric electrical studies of boundary layer phenomena through a height range by mounting instruments on cable cars traveling between the valley floor and mountain tops in the Alps. The airborne measurements described here extend this approach. Relating the electrical structure of the atmosphere to its dynamic structure poses an interesting problem which may contribute to our understanding of the atmosphere.

The Model of Complex Structure of Quark

NASA Astrophysics Data System (ADS)

Liu, Rongwu

2017-09-01

In Quantum Chromodynamics, quark is known as a kind of point-like fundamental particle which carries mass, charge, color, and flavor, strong interaction takes place between quarks by means of exchanging intermediate particles-gluons. An important consequence of this theory is that, strong interaction is a kind of short-range force, and it has the features of ``asymptotic freedom'' and ``quark confinement''. In order to reveal the nature of strong interaction, the ``bag'' model of vacuum and the ``string'' model of string theory were proposed in the context of quantum mechanics, but neither of them can provide a clear interaction mechanism. This article formulates a new mechanism by proposing a model of complex structure of quark, it can be outlined as follows: (1) Quark (as well as electron, etc) is a kind of complex structure, it is composed of fundamental particle (fundamental matter mass and electricity) and fundamental volume field (fundamental matter flavor and color) which exists in the form of limited volume; fundamental particle lies in the center of fundamental volume field, forms the ``nucleus'' of quark. (2) As static electric force, the color field force between quarks has classical form, it is proportional to the square of the color quantity carried by each color field, and inversely proportional to the area of cross section of overlapping color fields which is along force direction, it has the properties of overlap, saturation, non-central, and constant. (3) Any volume field undergoes deformation when interacting with other volume field, the deformation force follows Hooke's law. (4) The phenomena of ``asymptotic freedom'' and ``quark confinement'' are the result of color field force and deformation force.

Silicon-on-insulator field effect transistor with improved body ties for rad-hard applications

DOEpatents

Schwank, James R.; Shaneyfelt, Marty R.; Draper, Bruce L.; Dodd, Paul E.

2001-01-01

A silicon-on-insulator (SOI) field-effect transistor (FET) and a method for making the same are disclosed. The SOI FET is characterized by a source which extends only partially (e.g. about half-way) through the active layer wherein the transistor is formed. Additionally, a minimal-area body tie contact is provided with a short-circuit electrical connection to the source for reducing floating body effects. The body tie contact improves the electrical characteristics of the transistor and also provides an improved single-event-upset (SEU) radiation hardness of the device for terrestrial and space applications. The SOI FET also provides an improvement in total-dose radiation hardness as compared to conventional SOI transistors fabricated without a specially prepared hardened buried oxide layer. Complementary n-channel and p-channel SOI FETs can be fabricated according to the present invention to form integrated circuits (ICs) for commercial and military applications.

Utilization of electromigration in civil and environmental engineering--processes, transport rates and matrix changes.

PubMed

Ottosen, Lisbeth M; Christensen, Iben V; Rorig-Dalgård, Inge; Jensen, Pernille E; Hansen, Henrik K

2008-07-01

Electromigration (movement of ions in an applied electric field) is utilized for supply or extraction of ions from various porous materials within both civil and environmental engineering. In civil engineering, most research has been conducted on the removal of chlorides from concrete to hinder reinforcement corrosion while in environmental engineering remediation of heavy metal polluted soil is the issue most studied. Never the less, experiments have been conducted with utilization for several other materials and purposes within both engineering fields. Even though there are many topics of common interest in the use of electromigration for the two fields, there is no tradition for collaboration. The present paper is a review with the aim of pointing out areas of shared interest. Focus is laid on the purposes of the different processes, transport rates of various ions in different materials and on changes in the matrix itself. Desorption and dissolution of the target elements into ionic form is a key issue to most of the processes, and can be the limiting step. The removal rate is generally below 1 cm day(- 1), but it can be much less than 1 mm day(- 1) when desorption is slow and insufficient. Matrix changes occurs under the action of the applied electric field and it includes both physico-chemical and hydrological changes. Some of the solid phases is weathered and new can be formed. Increased fundamental understanding of the effects and side effects, when applying the electric field to a porous material, can lead to improvement of the known technologies and possibly to new applications.

Interaction of two-dimensional magnetoexcitons

NASA Astrophysics Data System (ADS)

Dumanov, E. V.; Podlesny, I. V.; Moskalenko, S. A.; Liberman, M. A.

2017-04-01

We study interaction of the two-dimensional magnetoexcitons with in-plane wave vector k→∥ = 0 , taking into account the influence of the excited Landau levels (ELLs) and of the external electric field perpendicular to the surface of the quantum well and parallel to the external magnetic field. It is shown that the account of the ELLs gives rise to the repulsion between the spinless magnetoexcitons with k→∥ = 0 in the Fock approximation, with the interaction constant g decreasing inverse proportional to the magnetic field strength B (g (0) ∼ 1 / B) . In the presence of the perpendicular electric field the Rashba spin-orbit coupling (RSOC), Zeeman splitting (ZS) and nonparabolicity of the heavy-hole dispersion law affect the Landau quantization of the electrons and holes. They move along the new cyclotron orbits, change their Coulomb interactions and cause the interaction between 2D magnetoexcitons with k→∥ = 0 . The changes of the Coulomb interactions caused by the electrons and by the holes moving with new cyclotron orbits are characterized by some coefficients, which in the absence of the electric field turn to be unity. The differences between these coefficients of the electron-hole pairs forming the magnetoexcitons determine their affinities to the interactions. The interactions between the homogeneous, semihomogeneous and heterogeneous magnetoexcitons forming the symmetric states with the same signs of their affinities are attractive whereas in the case of different sign affinities are repulsive. In the heterogeneous asymmetric states the interactions have opposite signs in comparison with the symmetric states. In all these cases the interaction constant g have the dependence g (0) 1 /√{ B} .

Martian Dust Devil Electron Avalanche Process and Associated Electrochemistry

NASA Technical Reports Server (NTRS)

Jackson, Telana L.; Farrell, William M.; Delory, Gregory T.; Nithianandam, Jeyasingh

2010-01-01

Mars' dynamic atmosphere displays localized dust devils and larger, global dust storms. Based on terrestrial analog studies, electrostatic modeling, and laboratory work these features will contain large electrostatic fields formed via triboelectric processes. In the low-pressure Martian atmosphere, these fields may create an electron avalanche and collisional plasma due to an increase in electron density driven by the internal electrical forces. To test the hypothesis that an electron avalanche is sustained under these conditions, a self-consistent atmospheric process model is created including electron impact ionization sources and electron losses via dust absorption, electron dissociation attachment, and electron/ion recombination. This new model is called the Dust Devil Electron Avalanche Model (DDEAM). This model solves simultaneously nine continuity equations describing the evolution of the primary gaseous chemical species involved in the electrochemistry. DDEAM monitors the evolution of the electrons and primary gas constituents, including electron/water interactions. We especially focus on electron dynamics and follow the electrons as they evolve in the E field driven collisional gas. When sources and losses are self-consistently included in the electron continuity equation, the electron density grows exponentially with increasing electric field, reaching an equilibrium that forms a sustained time-stable collisional plasma. However, the character of this plasma differs depending upon the assumed growth rate saturation process (chemical saturation versus space charge). DDEAM also shows the possibility of the loss of atmospheric methane as a function of electric field due to electron dissociative attachment of the hydrocarbon. The methane destruction rates are presented and can be included in other larger atmospheric models.

Electrodynamics of frictional interaction in tribolink “metal-polymer”

NASA Astrophysics Data System (ADS)

Volchenko, N. A.; Krasin, P. S.; Volchenko, A. I.; Zhuravlev, D. Yu

2018-03-01

The materials of the article illustrate the estimation of the energy loading of a metal friction element in the metal-electrolyte-polymer friction pair while forming various types of double electrical layers with the release of its thermal stabilization state. The energy loading of the contact spots of the microprotrusions of the friction pairs of braking devices depends to a large extent on the electrical, thermal and chemical fields that are of a different nature to an allowable temperature and are above the surface layers of the polymer patch. The latter is significantly influenced by double electrical layers that are formed at the boundaries of the phases “metal-metal”, “metal-polymer”, “metal-semiconductor”, “semiconductor-semiconductor” and “metal-electrolyte”. When two electrically conducting phases come into contact with electrothermomechanical friction, a difference in electrical potentials arises, which is due to the formation of a double electric layer, that is an asymmetric distribution of charged particles near the phase boundary. The structure of the double electric layer does not matter for the magnitude of the reversible electrode potential, which is determined by the variation of the isobaric-isothermal potential of the corresponding electrochemical reaction.

Determination of the space-charge field amplitude in polymeric photorefractive polymers.

PubMed

Hwang, Ui-Jung; Choi, Chil-Sung; Vuong, Nguyen Quoc; Kim, Nakjoong

2005-12-22

The space-charge field built in a polymeric photorefractive polymer was calculated by a simple method based on the oriented gas model. When anisotropic chromophores in a photorefractive polymer were exposed to an external field, they oriented preferentially to exhibit a birefringence. Then, under illumination of two coherent beams and an external field, they reoriented to form a photorefractive grating. During the formation of the grating, the chromophores were reoriented by the space-charge field as well as by the external applied field. The birefringence induced in the material by an external electric field was determined by measuring the transmittance of the sample which is placed between crossed polarizers, where birefringence depicts the orientation of the chromophores. By measuring the diffraction efficiency with a modified degenerate four-wave mixing setup, the index amplitude of the grating was determined. Finally, the space-charge field was determined by comparing the diffraction efficiency with the birefringence with respect to the applied electric field. In our study, the space-charge field was about 20% of the external applied field, which coincided with previous results obtained from our laboratory.

Terahertz radiation induced chaotic electron transport in semiconductor superlattices with a tilted magnetic field.

PubMed

Wang, C; Wang, F; Cao, J C

2014-09-01

Chaotic electron transport in semiconductor superlattice induced by terahertz electric field that is superimposed on a dc electric field along the superlattice axis are studied using the semiclassical motion equations including the effect of dissipation. A magnetic field that is tilted relative to the superlattice axis is also applied to the system. Numerical simulation shows that electrons in superlattice miniband exhibit complicate nonlinear oscillating modes with the influence of terahertz radiation. Transitions between frequency-locking and chaos via pattern forming bifurcations are observed with the varying of terahertz amplitude. It is found that the chaotic regions gradually contract as the dissipation increases. We attribute the appearance of complicate nonlinear oscillation in superlattice to the interaction between terahertz radiation and internal cooperative oscillating mode relative to Bloch oscillation and cyclotron oscillation.

Electron Field Emission Properties of Textured Platinum Surfaces

NASA Technical Reports Server (NTRS)

Sovey, James S.

2002-01-01

During ground tests of electric microthrusters and space tests of electrodynamic tethers the electron emitters must successfully operate at environmental pressures possibly as high as 1x10(exp -4) Pa. High partial pressures of oxygen, nitrogen, and water vapor are expected in such environments. A textured platinum surface was used in this work for field emission cathode assessments because platinum does not form oxide films at low temperatures. Although a reproducible cathode conditioning process did not evolve from this work, some short term tests for periods of 1 to 4 hours showed no degradation of emission current at an electric field of 8 V/mm and background pressures of about 1x10(exp -6) Pa. Increases of background pressure by air flow to about 3x10(exp -4) Pa yield a hostile environment for the textured platinum field emission cathode.

STM studies of an atomic-scale gate electrode formed by a single charged vacancy in GaAs

NASA Astrophysics Data System (ADS)

Lee, Donghun; Daughton, David; Gupta, Jay

2009-03-01

Electric-field control of spin-spin interactions at the atomic level is desirable for the realization of spintronics and spin-based quantum computation. Here we demonstrate the realization of an atomic-scale gate electrode formed by a single charged vacancy on the GaAs(110) surface[1]. We can position these vacancies with atomic precision using the tip of a home-built, low temperature STM. Tunneling spectroscopy of single Mn acceptors is used to quantify the electrostatic field as a function of distance from the vacancy. Single Mn acceptors are formed by substituting Mn adatoms for Ga atoms in the first layer of the p-GaAs(110) surface[2]. Depending on the distance, the in-gap resonance of single Mn acceptors can shift as much as 200meV. Our data indicate that the electrostatic field decays according to a screened Coulomb potential. The charge state of the vacancy can be switched to neutral, as evidenced by the Mn resonance returning to its unperturbed position. Reversible control of the local electric field as well as charged states of defects in semiconductors can open new insights such as realizing an atomic-scale gate control and studying spin-spin interactions in semiconductors. http://www.physics.ohio-state.edu/sim jgupta [1] D. Lee and J.A. Gupta (in preparation) [2] D. Kitchen et al., Nature 442, 436-439 (2006)

Nonlinear dielectric effects in liquids: a guided tour

NASA Astrophysics Data System (ADS)

Richert, Ranko

2017-09-01

Dielectric relaxation measurements probe how the polarization of a material responds to the application of an external electric field, providing information on structure and dynamics of the sample. In the limit of small fields and thus linear response, such experiments reveal the properties of the material in the same thermodynamic state it would have in the absence of the external field. At sufficiently high fields, reversible changes in enthalpy and entropy of the system occur even at constant temperature, and these will in turn alter the polarization responses. The resulting nonlinear dielectric effects feature field induced suppressions (saturation) and enhancements (chemical effect) of the amplitudes, as well as time constant shifts towards faster (energy absorption) and slower (entropy reduction) dynamics. This review focuses on the effects of high electric fields that are reversible and observed at constant temperature for single component glass-forming liquids. The experimental challenges involved in nonlinear dielectric experiments, the approaches to separating and identifying the different sources of nonlinear behavior, and the current understanding of how high electric fields affect dielectric materials will be discussed. Covering studies from Debye’s initial approach to the present state-of-the-art, it will be emphasized what insight can be gained from the nonlinear responses that are not available from dielectric relaxation results obtained in the linear regime.

The use of an electric field in increasing the resistance of plants to the action of unfavorable space flight factors

NASA Astrophysics Data System (ADS)

Nechitailo, G.; Gordeev, A.

The key role in increasing the resistance of plants to unfavorable space flight factors is assigned to biomembranes of root cells. It is these biomembranes on which numerous biochemical and biophysical processes determining the adaptive capacity of plant organisms occur. In the initial period of exposure to unfavorable space flight factors the adaptational reactions of the plant organism undoubtedly increase its resistance. But the intensification of removal of H+ ions through the plasmalemma with an increase of the external influence sharply raises the quantity of cations leaving the cell, which leads to the accumu lation of a considerable quantity of intracellular negative charges. These charges together with negative charges built in the membrane force protons to concentrate on the external surface of the membrane. Since protons have a very strong electric field, they form such a charge of which the electric field is about from several to hundreds of V/cm. The concentration of positive charges of protons entails the formation of a double electric field which extremely impedes the diffusion of other ions. Thus, a proton barrier is formed. Its length can be very considerable due to which the whole process of transmembrane energy and mass-transfer is disturbed. The proton barrier is easily destroyed by a weak electric field created in the root zone. In experiment on electrostimulation of different plants under space flight conditions at the orbital station MIR the absorption of nutrient elements by the root system increased to the optimal level, the ratio of physiologically active substances in the rhizosphere was normalized, the content of chlorophyll, carotin, and ascorbic acid in leaves corresponded to the ground-based control. Understanding of the mechanism of formation of a proton barrier on the plasmalemma of root cells as a result of the response of plants to the negative action of external factors (microgravity) is of great importance. It allows the possibility of life support of the vegetable kingdom in extreme conditions to be estimated in a new way.

The use of an electric field in increasing the resistance of plants to the action of unfavorable space flight factors

NASA Astrophysics Data System (ADS)

Nechitailo, G.; Gordeev, A.

2004-01-01

The key role in increasing the resistance of plants to unfavorable space flight factors is assigned to biomembranes of root cells. It is these biomembranes in which numerous biochemical and biophysical processes determining the adaptive capacity of plant organisms occur. In the initial period of exposure to unfavorable space flight factors the adaptation reactions of the plant organism undoubtedly increase its resistance. But the intensification of removal of H + ions through the plasmalemma with an increase of the external influence sharply raises the quantity of cations leaving the cell, which leads to the accumulation of a considerable quantity of intracellular negative charges. These charges together with negative charges built in the membrane force protons to concentrate on the external surface of the membrane. Since protons have a very strong electric field, they form such a charge of which the electric field is about from several to hundreds of V/cm. The concentration of positive charges of protons entails the formation of a double electric field which extremely impedes the diffusion of other ions. Thus, a proton barrier is formed. Its length can be very considerable due to which the whole process of transmembrane energy and mass-transfer is disturbed. The proton barrier is easily destroyed by a weak electric field created in the root zone. In experiments on electrostimulation of different plants under space flight conditions at the orbital station MIR the absorption of nutrient elements by the root system increased to the optimal level, the ratio of physiologically active substances in the rhizosphere was normalized, the content of chlorophyll, carotin, and ascorbic acid in leaves corresponded to the ground-based control. Understanding of the mechanism of formation of a proton barrier on the plasmalemma of root cells as a result of the response of plants to the negative action of external factors (microgravity) is of great importance. It allows the possibility of life support of the vegetable kingdom in extreme conditions to be estimated in a new way.

KINETIC-J: A computational kernel for solving the linearized Vlasov equation applied to calculations of the kinetic, configuration space plasma current for time harmonic wave electric fields

NASA Astrophysics Data System (ADS)

Green, David L.; Berry, Lee A.; Simpson, Adam B.; Younkin, Timothy R.

2018-04-01

We present the KINETIC-J code, a computational kernel for evaluating the linearized Vlasov equation with application to calculating the kinetic plasma response (current) to an applied time harmonic wave electric field. This code addresses the need for a configuration space evaluation of the plasma current to enable kinetic full-wave solvers for waves in hot plasmas to move beyond the limitations of the traditional Fourier spectral methods. We benchmark the kernel via comparison with the standard k →-space forms of the hot plasma conductivity tensor.

Structures of water molecules in carbon nanotubes under electric fields

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

Winarto,; Takaiwa, Daisuke; Yamamoto, Eiji

2015-03-28

Carbon nanotubes (CNTs) are promising for water transport through membranes and for use as nano-pumps. The development of CNT-based nanofluidic devices, however, requires a better understanding of the properties of water molecules in CNTs because they can be very different from those in the bulk. Using all-atom molecular dynamics simulations, we investigate the effect of axial electric fields on the structure of water molecules in CNTs having diameters ranging from (7,7) to (10,10). The water dipole moments were aligned parallel to the electric field, which increases the density of water inside the CNTs and forms ordered ice-like structures. The electricmore » field induces the transition from liquid to ice nanotubes in a wide range of CNT diameters. Moreover, we found an increase in the lifetime of hydrogen bonds for water structures in the CNTs. Fast librational motion breaks some hydrogen bonds, but the molecular pairs do not separate and the hydrogen bonds reform. Thus, hydrogen bonds maintain the water structure in the CNTs, and the water molecules move collectively, decreasing the axial diffusion coefficient and permeation rate.« less

Electric manipulation of ultracold polar ^40K^87Rb molecules in a magnetic field

NASA Astrophysics Data System (ADS)

Quéméner, Goulven; Bohn, John

2009-05-01

Ultracold fermionic polar molecules of ^40K^87Rb in their absolute rovibronic ground state (v=0,n=0,^1σ) have been created recently [1] in a magnetic trap and open new perspectives to create fermionic degenerate gases of polar molecules. To achieve this goal, it is very important to understand the collisional properties of such molecules under magnetic and electric fields. In our presentation, we investigate ground state fermionic ^40K^87Rb + ^40K^87Rb collisions in the presence of a magnetic field and explore the possibility to control these collisions when an electric field is applied. We will explore the main physical processes that can lead to such manipulation. This problem is complicated by the Zeeman and Stark splitting of all levels of the polar molecules and by the possibility of forming ^40K2 + ^87Rb2 chemical products. 1 - K.-K. Ni, S. Ospelkaus, M. H. G. de Miranda, A. Pe'er, B. Neyenhuis, J. J. Zirbel, S. Kotochigova, P. S. Julienne, D. S. Jin, and J. Ye, Science 322, 231 (2008).

Generation and control of polarization-entangled photons from GaAs island quantum dots by an electric field

PubMed Central

Ghali, Mohsen; Ohtani, Keita; Ohno, Yuzo; Ohno, Hideo

2012-01-01

Semiconductor quantum dots are potential sources for generating polarization-entangled photons efficiently. The main prerequisite for such generation based on biexciton–exciton cascaded emission is to control the exciton fine-structure splitting. Among various techniques investigated for this purpose, an electric field is a promising means to facilitate the integration into optoelectronic devices. Here we demonstrate the generation of polarization-entangled photons from single GaAs quantum dots by an electric field. In contrast to previous studies, which were limited to In(Ga)As quantum dots, GaAs island quantum dots formed by a thickness fluctuation were used because they exhibit a larger oscillator strength and emit light with a shorter wavelength. A forward voltage was applied to a Schottky diode to control the fine-structure splitting. We observed a decrease and suppression in the fine-structure splitting of the studied single quantum dot with the field, which enabled us to generate polarization-entangled photons with a high fidelity of 0.72±0.05. PMID:22314357

A current disruption mechanism in the neutral sheet - A possible trigger for substorm expansions

NASA Technical Reports Server (NTRS)

Lui, A. T. Y.; Mankofsky, A.; Chang, C.-L.; Papadopoulos, K.; Wu, C. S.

1990-01-01

A linear analysis is performed to investigate the kinetic cross-field streaming instability in the earth's magnetotail neutral sheet region. Numerical solution of the dispersion equation shows that the instability can occur under conditions expected for the neutral sheet just prior to the onset of substorm expansion. The excited waves are obliquely propagating whistlers with a mixed polarization in the lower hybrid frequency range. The ensuing turbulence of this instability can lead to a local reduction of the cross-tail current causing it to continue through the ionosphere to form a substorm current wedge. A substorm expansion onset scenario is proposed based on this instability in which the relative drift between ions and electrons is primarily due to unmagnetized ions undergoing current sheet acceleration in the presence of a cross-tail electric field. The required electric field strength is within the range of electric field values detected in the neutral sheet region during substorm intervals. The skew in local time of substorm onset location and the three conditions under which substorm onset is observed can be understood on the basis of the proposed scenario.

Material cutting, shaping, and forming: A compilation

NASA Technical Reports Server (NTRS)

1974-01-01

Information is presented concerning cutting, shaping, and forming of materials, and the equipment and techniques required for utilizing these materials. The use of molds, electrical fields, and mechanical devices are related to forming materials. Material cutting methods by devices including borers and slicers are presented along with chemical techniques. Shaping and fabrication techniques are described for tubing, honeycomb panels, and ceramic structures. The characteristics of the materials are described. Patent information is included.

Electric Field Control of Magnetism Using BiFeO3-Based Heterostructures

DTIC Science & Technology

2014-04-22

dissipation in the form of heat has become a center stage issue for the microelectronics industry. By taking advantage of the strong correlations...speed and storage density, significant energy dissipation in the form of heat has become a center stage issue for the microelectronics industry. By...and storage density, significant energy dissipation in the form of heat has become a center stage issue for the microelectronics industry. By taking

Free electron laser

DOEpatents

Villa, Francesco

1990-01-01

A high gain, single-pass free electron laser formed of a high brilliance electron injector source, a linear accelerator which imparts high energy to the electron beam, and an undulator capable of extremely high magnetic fields, yet with a very short period. The electron injector source is the first stage (gap) of the linear accelerator or a radial line transformer driven by fast circular switch. The linear accelerator is formed of a plurality of accelerating gaps arranged in series. These gaps are energized in sequence by releasing a single pulse of energy which propagates simultaneously along a plurality of transmission lines, each of which feeds the gaps. The transmission lines are graduated in length so that pulse power is present at each gap as the accelerated electrons pass therethrough. The transmission lines for each gap are open circuited at their ends. The undualtor has a structure similar to the accelerator, except that the transmission lines for each gap are substantially short circuited at their ends, thus converting the electric field into magnetic field. A small amount of resistance is retained in order to generate a small electric field for replenishing the electron bunch with the energy lost as it traverses through the undulator structure.

Quantization of charged fields in the presence of critical potential steps

NASA Astrophysics Data System (ADS)

Gavrilov, S. P.; Gitman, D. M.

2016-02-01

QED with strong external backgrounds that can create particles from the vacuum is well developed for the so-called t -electric potential steps, which are time-dependent external electric fields that are switched on and off at some time instants. However, there exist many physically interesting situations where external backgrounds do not switch off at the time infinity. E.g., these are time-independent nonuniform electric fields that are concentrated in restricted space areas. The latter backgrounds represent a kind of spatial x -electric potential steps for charged particles. They can also create particles from the vacuum, the Klein paradox being closely related to this process. Approaches elaborated for treating quantum effects in the t -electric potential steps are not directly applicable to the x -electric potential steps and their generalization for x -electric potential steps was not sufficiently developed. We believe that the present work represents a consistent solution of the latter problem. We have considered a canonical quantization of the Dirac and scalar fields with x -electric potential step and have found in- and out-creation and annihilation operators that allow one to have particle interpretation of the physical system under consideration. To identify in- and out-operators we have performed a detailed mathematical and physical analysis of solutions of the relativistic wave equations with an x -electric potential step with subsequent QFT analysis of correctness of such an identification. We elaborated a nonperturbative (in the external field) technique that allows one to calculate all characteristics of zero-order processes, such, for example, scattering, reflection, and electron-positron pair creation, without radiation corrections, and also to calculate Feynman diagrams that describe all characteristics of processes with interaction between the in-, out-particles and photons. These diagrams have formally the usual form, but contain special propagators. Expressions for these propagators in terms of in- and out-solutions are presented. We apply the elaborated approach to two popular exactly solvable cases of x -electric potential steps, namely, to the Sauter potential and to the Klein step.

Electric-field control of tri-state phase transformation with a selective dual-ion switch

NASA Astrophysics Data System (ADS)

Lu, Nianpeng; Zhang, Pengfei; Zhang, Qinghua; Qiao, Ruimin; He, Qing; Li, Hao-Bo; Wang, Yujia; Guo, Jingwen; Zhang, Ding; Duan, Zheng; Li, Zhuolu; Wang, Meng; Yang, Shuzhen; Yan, Mingzhe; Arenholz, Elke; Zhou, Shuyun; Yang, Wanli; Gu, Lin; Nan, Ce-Wen; Wu, Jian; Tokura, Yoshinori; Yu, Pu

2017-06-01

Materials can be transformed from one crystalline phase to another by using an electric field to control ion transfer, in a process that can be harnessed in applications such as batteries, smart windows and fuel cells. Increasing the number of transferrable ion species and of accessible crystalline phases could in principle greatly enrich material functionality. However, studies have so far focused mainly on the evolution and control of single ionic species (for example, oxygen, hydrogen or lithium ions). Here we describe the reversible and non-volatile electric-field control of dual-ion (oxygen and hydrogen) phase transformations, with associated electrochromic and magnetoelectric effects. We show that controlling the insertion and extraction of oxygen and hydrogen ions independently of each other can direct reversible phase transformations among three different material phases: the perovskite SrCoO3-δ (ref. 12), the brownmillerite SrCoO2.5 (ref. 13), and a hitherto-unexplored phase, HSrCoO2.5. By analysing the distinct optical absorption properties of these phases, we demonstrate selective manipulation of spectral transparency in the visible-light and infrared regions, revealing a dual-band electrochromic effect that could see application in smart windows. Moreover, the starkly different magnetic and electric properties of the three phases—HSrCoO2.5 is a weakly ferromagnetic insulator, SrCoO3-δ is a ferromagnetic metal, and SrCoO2.5 is an antiferromagnetic insulator—enable an unusual form of magnetoelectric coupling, allowing electric-field control of three different magnetic ground states. These findings open up opportunities for the electric-field control of multistate phase transformations with rich functionalities.

Hybrid immersed interface-immersed boundary methods for AC dielectrophoresis

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

Hossan, Mohammad Robiul; Department of Engineering and Physics, University of Central Oklahoma, Edmond, OK 73034-5209; Dillon, Robert

2014-08-01

Dielectrophoresis, a nonlinear electrokinetic transport mechanism, has become popular in many engineering applications including manipulation, characterization and actuation of biomaterials, particles and biological cells. In this paper, we present a hybrid immersed interface–immersed boundary method to study AC dielectrophoresis where an algorithm is developed to solve the complex Poisson equation using a real variable formulation. An immersed interface method is employed to obtain the AC electric field in a fluid media with suspended particles and an immersed boundary method is used for the fluid equations and particle transport. The convergence of the proposed algorithm as well as validation of themore » hybrid scheme with experimental results is presented. In this paper, the Maxwell stress tensor is used to calculate the dielectrophoretic force acting on particles by considering the physical effect of particles in the computational domain. Thus, this study eliminates the approximations used in point dipole methods for calculating dielectrophoretic force. A comparative study between Maxwell stress tensor and point dipole methods for computing dielectrophoretic forces are presented. The hybrid method is used to investigate the physics of dielectrophoresis in microfluidic devices using an AC electric field. The numerical results show that with proper design and appropriate selection of applied potential and frequency, global electric field minima can be obtained to facilitate multiple particle trapping by exploiting the mechanism of negative dielectrophoresis. Our numerical results also show that electrically neutral particles form a chain parallel to the applied electric field irrespective of their initial orientation when an AC electric field is applied. This proposed hybrid numerical scheme will help to better understand dielectrophoresis and to design and optimize microfluidic devices.« less

Electrical Programming of Soft Matter: Using Temporally Varying Electrical Inputs To Spatially Control Self Assembly.

PubMed

Yan, Kun; Liu, Yi; Zhang, Jitao; Correa, Santiago O; Shang, Wu; Tsai, Cheng-Chieh; Bentley, William E; Shen, Jana; Scarcelli, Giuliano; Raub, Christopher B; Shi, Xiao-Wen; Payne, Gregory F

2018-02-12

The growing importance of hydrogels in translational medicine has stimulated the development of top-down fabrication methods, yet often these methods lack the capabilities to generate the complex matrix architectures observed in biology. Here we show that temporally varying electrical signals can cue a self-assembling polysaccharide to controllably form a hydrogel with complex internal patterns. Evidence from theory and experiment indicate that internal structure emerges through a subtle interplay between the electrical current that triggers self-assembly and the electrical potential (or electric field) that recruits and appears to orient the polysaccharide chains at the growing gel front. These studies demonstrate that short sequences (minutes) of low-power (∼1 V) electrical inputs can provide the program to guide self-assembly that yields hydrogels with stable, complex, and spatially varying structure and properties.

Ephemeral Electric Potential and Electric Field Sensor

NASA Technical Reports Server (NTRS)

Generazio, Edward R. (Inventor)

2017-01-01

Systems, methods, and devices of the various embodiments provide for the minimization of the effects of intrinsic and extrinsic leakage electrical currents enabling true measurements of electric potentials and electric fields. In an embodiment, an ephemeral electric potential and electric field sensor system may have at least one electric field sensor and a rotator coupled to the electric field sensor and be configured to rotate the electric field sensor at a quasi-static frequency. In an embodiment, ephemeral electric potential and electric field measurements may be taken by rotating at least one electric field sensor at a quasi-static frequency, receiving electrical potential measurements from the electric field sensor when the electric field sensor is rotating at the quasi-static frequency, and generating and outputting images based at least in part on the received electrical potential measurements.

Electric fields and vector potentials of thin cylindrical antennas

NASA Astrophysics Data System (ADS)

King, Ronold W. P.

1990-09-01

The vector potential and electric field generated by the current in a center-driven or parasitic dipole antenna that extends from z = -h to z = h are investigated for each of the several components of the current. These include sin k(h - absolute value of z), sin k (absolute value of z) - sin kh, cos kz - cos kh, and cos kz/2 - cos kh/2. Of special interest are the interactions among the variously spaced elements in parallel nonstaggered arrays. These depend on the mutual vector potentials. It is shown that at a radial distance rho approximately = h and in the range z = -h to h, the vector potentials due to all four components become alike and have an approximately plane-wave form. Simple approximate formulas for the electric fields and vector potentials generated by each of the four distributions are derived and compared with the exact results. The application of the new formulas to large arrays is discussed.

Electrokinetic effects on motion of submicron particles in microchannel

NASA Astrophysics Data System (ADS)

Sato, Yohei; Hishida, Koichi

2006-11-01

Two-fluid mixing utilizing electrokinetically driven flow in a micro-channel is investigated by micron-resolution particle image velocimetry and an image processing technique. Submicron particles are transported and mixed with deionized water by electrophoresis. The particle electrophoretic velocity that is proportional to an applied electric field is measured in a closed cell, which is used to calculate the electroosmotic flow velocity. At a constant electric field, addition of pressure-driven flow to electrokinetically driven flow in a T-shaped micro-channel enhances two-fluid mixing because the momentum flux is increased. On the other hand, on application of an alternative sinusoidal electric field, the velocity difference between pressure-driven and electroosmotic flows has a significant effect on increasing the length of interface formed between two fluids. It is concluded from the present experiments that the transport and mixing process in the micro-channel will be enhanced by accurate flow-rate control of both pressure-driven and electroosmotic flows.

Low-Voltage Paper Isotachophoresis Device for DNA Focusing

PubMed Central

Li, Xiang; Luo, Long; Crooks, Richard M.

2015-01-01

We present a new paper-based isotachophoresis (ITP) device design for focusing DNA samples having lengths ranging from 23 to at least 1517 bp. DNA is concentrated by more than two orders of magnitude within 4 min. The key component of this device is a 2 mm-long, 2 mm-wide circular paper channel formed by concertina folding a paper strip and aligning the circular paper zones on each layer. Due to the short channel length, a high electric field of ~16 kV/m is easily generated in the paper channel using two 9 V batteries. The multilayer architecture also enables convenient reclamation and analysis of the sample after ITP focusing by simply opening the origami paper and cutting out the desired layers. We profiled the electric field in the origami paper channel during ITP experiments using a nonfocusing fluorescent tracer. The result showed that focusing relies on formation and subsequent movement of a sharp electric field boundary between the leading and trailing electrolyte. PMID:26338530

Fabrication of field-effect transistor utilizing oriented thin film of octahexyl-substituted phthalocyanine and its electrical anisotropy based on columnar structure

NASA Astrophysics Data System (ADS)

Ohmori, Masashi; Nakatani, Mitsuhiro; Kajii, Hirotake; Miyamoto, Ayano; Yoneya, Makoto; Fujii, Akihiko; Ozaki, Masanori

2018-03-01

Field-effect transistors with molecularly oriented thin films of metal-free non-peripherally octahexyl-substituted phthalocyanine (C6PcH2), which characteristically form a columnar structure, have been fabricated, and the electrical anisotropy of C6PcH2 has been investigated. The molecularly oriented thin films of C6PcH2 were prepared by the bar-coating technique, and the uniform orientation in a large area and the surface roughness at a molecular level were observed by polarized spectroscopy and atomic force microscopy, respectively. The field effect mobilities parallel and perpendicular to the column axis of C6PcH2 were estimated to be (1.54 ± 0.24) × 10-2 and (2.10 ± 0.23) × 10-3 cm2 V-1 s-1, respectively. The electrical anisotropy based on the columnar structure has been discussed by taking the simulated results obtained by density functional theory calculation into consideration.

Large piezoelectricity in electric-field modified single crystals of SrTiO3

NASA Astrophysics Data System (ADS)

Khanbabaee, B.; Mehner, E.; Richter, C.; Hanzig, J.; Zschornak, M.; Pietsch, U.; Stöcker, H.; Leisegang, T.; Meyer, D. C.; Gorfman, S.

2016-11-01

Defect engineering is an effective and powerful tool to control the existing material properties and produce completely new ones, which are symmetry-forbidden in a defect-free crystal. For example, the application of a static electric field to a single crystal of SrTiO3 forms a strained near-surface layer through the migration of oxygen vacancies out of the area beneath the positively charged electrode. While it was previously shown that this near-surface phase holds pyroelectric properties, which are symmetry-forbidden in centrosymmetric bulk SrTiO3, this paper reports that the same phase is strongly piezoelectric. We demonstrate the piezoelectricity of this phase through stroboscopic time-resolved X-ray diffraction under alternating electric field and show that the effective piezoelectric coefficient d33 ranges between 60 and 100 pC/N. The possible atomistic origins of the piezoelectric activity are discussed as a coupling between the electrostrictive effect and spontaneous polarization of this near-surface phase.

Organic field effect transistors - Study of performance parameters for different dielectric layer thickness

NASA Astrophysics Data System (ADS)

Assis, Anu; Shahul Hameed T., A.; Predeep, P.

2017-06-01

Mobility and current handling capabilities of Organic Field Effect Transistor (OFET) are vitally important parameters in the electrical performance where the material parameters and thickness of different layers play significant role. In this paper, we report the simulation of an OFET using multi physics tool, where the active layer is pentacene and Poly Methyl Methacrylate (PMMA) forms the dielectric. Electrical characterizations of the OFET on varying the thickness of the dielectric layer from 600nm to 400nm are simulated and drain current, transconductance and mobility are analyzed. In the study it is found that even though capacitance increases with reduction in dielectric layer thickness, the transconductance effect is reflected many more times in the mobility which in turn could be attributed to the variations in transverse electric field. The layer thickness below 300nm may result in gate leakage current points to the requirement of optimizing the thickness of different layers for better performance.

ION MAGNETRON

DOEpatents

Gow, J.D.; Layman, R.W.

1962-10-31

A magnetohydrodynamic device or plasma generator of the ion magnetron class is described wherein a long central electrode is disposed along the axis of an evacuated cylinder. A radial electric field and an axial magnetic field are provided between the cylsnder and the electrode, forming a plasma trapping and heating region. For maximum effectiveness, neutral particles from the cylinder wall must be prevented from entering such region This is effected by forming a cylindrical sheath of electrons near the cylinder wall for ionizing undesired neutral particles, which are then trapped and removed by the magnetic field. An annular filament at one end of the device provides the electrons, which follow the axial magnetic field to a reflecting electrode at the opposite end of the device. (AEC)

Electric field stabilization of viscous liquid layers coating the underside of a surface

NASA Astrophysics Data System (ADS)

Anderson, Thomas G.; Cimpeanu, Radu; Papageorgiou, Demetrios T.; Petropoulos, Peter G.

2017-05-01

We investigate the electrostatic stabilization of a viscous thin film wetting the underside of a horizontal surface in the presence of an electric field applied parallel to the surface. The model includes the effect of bounding solid dielectric regions above and below the liquid-air system that are typically found in experiments. The competition between gravitational forces, surface tension, and the nonlocal effect of the applied electric field is captured analytically in the form of a nonlinear evolution equation. A semispectral solution strategy is employed to resolve the dynamics of the resulting partial differential equation. Furthermore, we conduct direct numerical simulations (DNS) of the Navier-Stokes equations using the volume-of-fluid methodology and assess the accuracy of the obtained solutions in the long-wave (thin-film) regime when varying the electric field strength from zero up to the point when complete stabilization occurs. We employ DNS to examine the limitations of the asymptotically derived behavior as the liquid layer thickness increases and find excellent agreement even beyond the regime of strict applicability of the asymptotic solution. Finally, the asymptotic and computational approaches are utilized to identify robust and efficient active control mechanisms allowing the manipulation of the fluid interface in light of engineering applications at small scales, such as mixing.

Out-of-plane strain and electric field tunable electronic properties and Schottky contact of graphene/antimonene heterostructure

NASA Astrophysics Data System (ADS)

Phuc, Huynh V.; Hieu, Nguyen N.; Hoi, Bui D.; Phuong, Le T. T.; Hieu, Nguyen V.; Nguyen, Chuong V.

2017-12-01

In this paper, the electronic properties of graphene/monolayer antimonene (G/m-Sb) heterostructure have been studied using the density functional theory (DFT). The effects of out-of-plane strain (interlayer coupling) and electric field on the electronic properties and Schottky contact of the G/m-Sb heterostructure are also investigated. The results show that graphene is bound to m-Sb layer by a weak van-der-Waals interaction with the interlayer distance of 3.50 Å and the binding energy per carbon atom of -39.62 meV. We find that the n-type Schottky contact is formed at the G/m-Sb heterostructure with the Schottky barrier height (SBH) of 0.60 eV. By varying the interlayer distance between graphene and the m-Sb layer we can change the n-type and p-type SBH at the G/m-Sb heterostructure. Especially, we find the transformation from n-type to p-type Schottky contact with decreasing the interlayer distance. Furthermore, the SBH and the Schottky contact could be controlled by applying the perpendicular electric field. With the positive electric field, electrons can easily transfer from m-Sb to graphene layer, leading to the transition from n-type to p-type Schottky contact.

Silicon-ion-implanted PMMA with nanostructured ultrathin layers for plastic electronics

NASA Astrophysics Data System (ADS)

Hadjichristov, G. B.; Ivanov, Tz E.; Marinov, Y. G.

2014-12-01

Being of interest for plastic electronics, ion-beam produced nanostructure, namely silicon ion (Si+) implanted polymethyl-methacrylate (PMMA) with ultrathin nanostructured dielectric (NSD) top layer and nanocomposite (NC) buried layer, is examined by electric measurements. In the proposed field-effect organic nanomaterial structure produced within the PMMA network by ion implantation with low energy (50 keV) Si+ at the fluence of 3.2 × 1016 cm-2 the gate NSD is ion-nanotracks-modified low-conductive surface layer, and the channel NC consists of carbon nanoclusters. In the studied ion-modified PMMA field-effect configuration, the gate NSD and the buried NC are formed as planar layers both with a thickness of about 80 nm. The NC channel of nano-clustered amorphous carbon (that is an organic semiconductor) provides a huge increase in the electrical conduction of the material in the subsurface region, but also modulates the electric field distribution in the drift region. The field effect via the gate NSD is analyzed. The most important performance parameters, such as the charge carrier field-effect mobility and amplification of this particular type of PMMA- based transconductance device with NC n-type channel and gate NSD top layer, are determined.

Projected Dipole Moments of Individual Two-Level Defects Extracted Using Circuit Quantum Electrodynamics.

PubMed

Sarabi, B; Ramanayaka, A N; Burin, A L; Wellstood, F C; Osborn, K D

2016-04-22

Material-based two-level systems (TLSs), appearing as defects in low-temperature devices including superconducting qubits and photon detectors, are difficult to characterize. In this study we apply a uniform dc electric field across a film to tune the energies of TLSs within. The film is embedded in a superconducting resonator such that it forms a circuit quantum electrodynamical system. The energy of individual TLSs is observed as a function of the known tuning field. By studying TLSs for which we can determine the tunneling energy, the actual p_{z}, dipole moments projected along the uniform field direction, are individually obtained. A distribution is created with 60 p_{z}. We describe the distribution using a model with two dipole moment magnitudes, and a fit yields the corresponding values p=p_{1}=2.8±0.2  D and p=p_{2}=8.3±0.4  D. For a strong-coupled TLS the vacuum-Rabi splitting can be obtained with p_{z} and tunneling energy. This allows a measurement of the circuit's zero-point electric-field fluctuations, in a method that does not need the electric-field volume.

Electron Dynamics in Nanostructures in Strong Laser Fields

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

Kling, Matthias

2014-09-11

The goal of our research was to gain deeper insight into the collective electron dynamics in nanosystems in strong, ultrashort laser fields. The laser field strengths will be strong enough to extract and accelerate electrons from the nanoparticles and to transiently modify the materials electronic properties. We aimed to observe, with sub-cycle resolution reaching the attosecond time domain, how collective electronic excitations in nanoparticles are formed, how the strong field influences the optical and electrical properties of the nanomaterial, and how the excitations in the presence of strong fields decay.

Mass spectrometer with magnetic pole pieces providing the magnetic fields for both the magnetic sector and an ion-type vacuum pump

NASA Technical Reports Server (NTRS)

Sieradski, L. M.; Giffin, C. E.; Nier, A. O. (Inventor)

1976-01-01

A mass spectrometer (MS) with unique magnetic pole pieces which provide a homogenous magnetic field across the gap of the MS magnetic sector as well as the magnetic field across an ion-type vacuum pump is disclosed. The pole pieces form the top and bottom sides of a housing. The housing is positioned so that portions of the pole pieces form part of the magnetic sector with the space between them defining the gap region of the magnetic sector, through which an ion beam passes. The pole pieces extend beyond the magnetic sector with the space between them being large enough to accommodate the electrical parts of an ion-type vacuum pump. The pole pieces which provide the magnetic field for the pump, together with the housing form the vacuum pump enclosure or housing.

Solar wind: Internal parameters driven by external source

NASA Technical Reports Server (NTRS)

Chertkov, A. D.

1995-01-01

A new concept interpreting solar wind parameters is suggested. The process of increasing twofold of a moving volume in the solar wind (with energy transfer across its surface which is comparable with its whole internal energy) is a more rapid process than the relaxation for the pressure. Thus, the solar wind is unique from the point of view of thermodynamics of irreversible processes. The presumptive source of the solar wind creation - the induction electric field of the solar origin - has very low entropy. The state of interplanetary plasma must be very far from the thermodynamic equilibrium. Plasma internal energy is contained mainly in non-degenerate forms (plasma waves, resonant plasma oscillations, electric currents). Microscopic oscillating electric fields in the solar wind plasma should be about 1 V/m. It allows one to describe the solar wind by simple dissipative MHD equations with small effective mean free path (required for hydrodynamical description), low value of electrical conductivity combined with very big apparent thermal conductivity (required for observed solar wind acceleration). These internal parameters are interrelated only due to their origin: they are externally driven. Their relation can change during the interaction of solar wind plasma with an obstacle (planet, spacecraft). The concept proposed can be verified by the special electric field measurements, not ruining the primordial plasma state.

Particle-in-cell simulations of asymmetric guide-field reconnection: quadrupolar structure of Hall magnetic field

NASA Astrophysics Data System (ADS)

Schmitz, R. G.; Alves, M. V.; Barbosa, M. V. G.

2017-12-01

One of the most important processes that occurs in Earth's magnetosphere is known as magnetic reconnection (MR). This process can be symmetric or asymmetric, depending basically on the plasma density and magnetic field in both sides of the current sheet. A good example of symmetric reconnection in terrestrial magnetosphere occurs in the magnetotail, where these quantities are similar on the north and south lobes. In the dayside magnetopause MR is asymmetric, since the plasma regimes and magnetic fields of magnetosheath and magnetosphere are quite different. Symmetric reconnection has some unique signatures. For example, the formation of a quadrupolar structure of Hall magnetic field and a bipolar Hall electric field that points to the center of the current sheet. The different particle motions in the presence of asymmetries change these signatures, causing the quadrupolar pattern to be distorted and forming a bipolar structure. Also, the bipolar Hall electric field is modified and gives rise to a single peak pointing toward the magnetosheat, considering an example of magnetopause reconnection. The presence of a guide-field can also distort the quadrupolar pattern, by giving a shear angle across the current sheet and altering the symmetric patterns, according to previous simulations and observations. Recently, a quadrupolar structure was observed in an asymmetric guide-field MR event using MMS (Magnetospheric Multiscale) mission data [Peng et al., JGR, 2017]. This event shows clearly that the density asymmetry and the guide-field were not sufficient to form signatures of asymmetric reconnection. Using the particle-in-cell code iPIC3D [Markidis et al, Mathematics and Computers in Simulation, 2010] with the MMS data from this event used to define input parameters, we found a quadrupolar structure of Hall magnetic field and a bipolar pattern of Hall electric field in ion scales, showing that our results are in an excellent agreement with the MMS observations. To our knowledge, this is the first time PIC simulations show this kind of results, since previous simulations have predicted bipolar pattern in the asymmetric guide-field reconnection.

Effect of temperature on compact layer of Pt electrode in PEMFCs by first-principles molecular dynamics calculations

NASA Astrophysics Data System (ADS)

He, Yang; Chen, Changfeng; Yu, Haobo; Lu, Guiwu

2017-01-01

Formation of the double-layer electric field and capacitance of the water-metal interface is of significant interest in physicochemical processes. In this study, we perform first- principles molecular dynamics simulations on the water/Pt(111) interface to investigate the temperature dependence of the compact layer electric field and capacitance based on the calculated charge densities. On the Pt (111) surface, water molecules form ice-like structures that exhibit more disorder along the height direction with increasing temperature. The Osbnd H bonds of more water molecules point toward the Pt surface to form Ptsbnd H covalent bonds with increasing temperature, which weaken the corresponding Osbnd H bonds. In addition, our calculated capacitance at 300 K is 15.2 mF/cm2, which is in good agreement with the experimental results. As the temperature increases from 10 to 450 K, the field strength and capacitance of the compact layer on Pt (111) first increase and then decrease slightly, which is significant for understanding the water/Pt interface from atomic level.

Final Technical Report: Electrohydrodynamic Tip Streaming

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

Basaran, Osman

2016-01-06

When subjected to strong electric fields, liquid drops and films form conical tips and emit thin jets from their tips. Such electrodydrodynamic (EDH) tip streaming or cone-jetting phenomena, which are sometimes referred to as electrospraying, occur widely in nature, e.g., in ejection of streams of small charged drops from pointed tips of raindrops in thunderclouds, and technology, e.g., in electrospray mass spectrometry or electric field-driven solvent extraction. More recently, EHD cone-jetting has emerged as a powerful technique for direct printing of solar cells, micro- and nano- particle production, and microencapsulation for controlled release. In many of the aforementioned situations, ofmore » equal importance to the processes by which one drop disintegrates to form several drops are those by which (a) two drops come together and coalesce and (b) two drops are coupled to form a double droplet system (DDS) or a capillary switch (CS). the main objective of this research program is to advance through simulation, theory, and experiment the breakup, coalescence, and oscillatory dynamics of single and pairs of charged as well as uncharged drops.« less

Formation of Dawn-Dusk Asymmetry in Earth's Magnetotail Thin Current Sheet: A Three-Dimensional Particle-In-Cell Simulation

NASA Astrophysics Data System (ADS)

Lu, San; Pritchett, P. L.; Angelopoulos, V.; Artemyev, A. V.

2018-04-01

Using a three-dimensional particle-in-cell simulation, we investigate the formation of dawn-dusk asymmetry in Earth's magnetotail. The magnetotail current sheet is compressed by an external driving electric field down to a thickness on the order of ion kinetic scales. In the resultant thin current sheet (TCS) where the magnetic field line curvature radius is much smaller than ion gyroradius, a significant portion of the ions becomes unmagnetized and decoupled from the magnetized electrons, giving rise to a Hall electric field Ez and an additional cross-tail current jy caused by the unmagnetized ions being unable to comove with the electrons in the Hall electric field. The Hall electric field transports via E × B drift magnetic flux and magnetized plasma dawnward, causing a reduction of the current sheet thickness and the normal magnetic field Bz on the duskside. This leads to an even stronger Hall effect (stronger jy and Ez) in the duskside TCS. Thus, due to the internal kinetic effects in the TCS, namely, the Hall effect and the associated dawnward E × B drift, the magnetotail dawn-dusk asymmetry forms in a short time without any global, long-term effects. The duskside preference of reconnection and associated dynamic phenomena (such as substorm onsets, dipolarizing flux bundles, fast flows, energetic particle injections, and flux ropes), which has been pervasively observed by spacecraft in the past 20 years, can thus be explained as a consequence of this TCS asymmetry.

Complex Pattern Formation from Current-Driven Dynamics of Single-Layer Homoepitaxial Islands on Crystalline Conducting Substrates

NASA Astrophysics Data System (ADS)

Kumar, Ashish; Dasgupta, Dwaipayan; Maroudas, Dimitrios

2017-07-01

We report a systematic study of complex pattern formation resulting from the driven dynamics of single-layer homoepitaxial islands on surfaces of face-centered-cubic (fcc) crystalline conducting substrates under the action of an externally applied electric field. The analysis is based on an experimentally validated nonlinear model of mass transport via island edge atomic diffusion, which also accounts for edge diffusional anisotropy. We analyze the morphological stability and simulate the field-driven evolution of rounded islands for an electric field oriented along the fast edge diffusion direction. For larger-than-critical island sizes on {110 } and {100 } fcc substrates, we show that multiple necking instabilities generate complex island patterns, including not-simply-connected void-containing islands mediated by sequences of breakup and coalescence events and distributed symmetrically with respect to the electric field direction. We analyze the dependence of the formed patterns on the original island size and on the duration of application of the external field. Starting from a single large rounded island, we characterize the evolution of the number of daughter islands and their average size and uniformity. The evolution of the average island size follows a universal power-law scaling relation, and the evolution of the total edge length of the islands in the complex pattern follows Kolmogorov-Johnson-Mehl-Avrami kinetics. Our study makes a strong case for the use of electric fields, as precisely controlled macroscopic forcing, toward surface patterning involving complex nanoscale features.

Resistive foil edge grading for accelerator and other high voltage structures

DOEpatents

Caporaso, George J.; Sampayan, Stephen F.; Sanders, David M.

2014-06-10

In a structure or device having a pair of electrical conductors separated by an insulator across which a voltage is placed, resistive layers are formed around the conductors to force the electric potential within the insulator to distribute more uniformly so as to decrease or eliminate electric field enhancement at the conductor edges. This is done by utilizing the properties of resistive layers to allow the voltage on the electrode to diffuse outwards, reducing the field stress at the conductor edge. Preferably, the resistive layer has a tapered resistivity, with a lower resistivity adjacent to the conductor and a higher resistivity away from the conductor. Generally, a resistive path across the insulator is provided, preferably by providing a resistive region in the bulk of the insulator, with the resistive layer extending over the resistive region.

Joule heating effects on particle immobilization in insulator-based dielectrophoretic devices

PubMed Central

Gallo-Villanueva, Roberto C.; Sano, Michael B.; Lapizco-Encinas, Blanca H.; Davalos, Rafael V.

2014-01-01

In this work, the temperature effects due to Joule heating obtained by application of a DC electric potential were investigated for a microchannel with cylindrical insulating posts employed for insulator based dielectrophoresis (iDEP). The conductivity of the suspending medium, the local electric field, and the gradient of the squared electric field, which directly affect the magnitude of the dielectrophoretic force exerted on particles, were computationally simulated employing COMSOL Multiphysics. It was observed that a temperature gradient is formed along the microchannel which redistributes the conductivity of the suspending medium leading to an increase of the dielectrophoretic force towards the inlet of the channel while decreasing towards the outlet. Experimental results are in good agreement with simulations on the particle trapping zones anticipated. This study demonstrates the importance of considering Joule heating effects when designing iDEP systems. PMID:24002905

Enhanced pearl-chain formation by electrokinetic interaction with the bottom surface of vessel.

PubMed

Nishimura, Satoshi; Matsumura, Hideo; Kosuge, Katsunori; Yamaguchi, Tomohiko

2007-08-14

Counterions in an electric double layer (EDL) around a colloidal particle accumulate on one side of the EDL and are deficient on the other side under an electric field, resulting in an imbalance of ionic concentration in the EDL, that is to say, the ionic polarization of EDL. It is well known that the ionic polarization of EDL induces electric dipole moments whereby the alignments of colloidal particles (e.g., pearl chains) are formed under alternating electric fields. In this study, we focus on the effect of the frequency of applied electric fields (100 Hz-1 kHz) on the alignment of silica particles settling at the bottom of a silica glass vessel. In digital imaging analyses for pearl chains of silica particles, it is confirmed that surface distances between two neighboring particles decrease but the number of particles in a pearl chain increases as the frequency of the applied electric field is lowered from 1 kHz to 100 Hz. More interestingly, electrical conductance measurements suggest that the induced ionic polarization of EDL around silica particles at the bottom of the silica vessel is enhanced as the frequency is lowered from 1 kHz to 100 Hz, whereas the ionic polarization around isolated silica particles in uniform dispersions is alleviated by the relaxation of ionic concentration in the EDL as a result of the diffusion of counterions. This curious phenomenon can be explained by considering that the ionic polarization of EDL of silica particles at the bottom of a vessel is affected by the electro-osmosis of the silica surface at the bottom of the vessel.

Scaling of Dielectric Breakdown Thresholds in Earth's and CO2-rich atmospheres: Impact for Predictions of Extraterrestrial Transient Luminous Events and Lightning Discharges

NASA Astrophysics Data System (ADS)

Riousset, J. A.

2016-12-01

Earth's atmospheric electricity manifests itself in the form of glow, corona, streamer, and leader discharges observed as Saint Elmo's fire, sprites, lightning and jets discharges, and other Transient Luminous Events (TLEs). All of these are types of dielectric breakdown, but are governed by different physics. In particular, their initiation is associated with the crossing of specific electric field thresholds: relativistic runaway, streamer propagation, conventional breakdown, or thermal runaway thresholds, some better understood than others. For example, the initiation of a lightning discharge is known to occur when the local electric field exceeds a value similar to relativistic runaway field, but the exact threshold, as well as the physical mechanisms at work, remain rather unclear to date. Scaling laws for electric fields (and other quantities) have been established by Pasko et al. [GRL, 25(12), 2123-2126, 1998] and Pasko [NATO Sci. Series, Springer, 253-311, 2006]. In this work, we develop profiles for initiation criteria in air and in other atmospheric environments. We further calculate their associated scaling laws to determine the ability to trigger lightning flashes and TLEs in our solar system. This lets us predict the likelihood of electrical discharges on, e.g., Mars, Venus and Titan, and calculate the expected electric field conditions, under which discharges have been observed on Jupiter, Saturn, Uranus, and Neptune [Leblanc et al., ISSI Spa. Sci. Series, Springer, 2008, Yair, Adv. Space Res., 50(3), 293-310, 2012]. Our results anticipate the arrival of ExoMars 2016's Schiaparelli module, which will provide the first records of electric field at the surface of the planet [Déprez et al., EGU GA, 16, 16613, 2014]. This research is also motived by the increasing probability of manned missions to Mars and the potential electrostatic hazards it may face [Yair, 2012], and by the role of electrical discharges in the creation of active radicals, some of which may be of biological importance [Miller, Science, 117, 528-529, 1953; Biochem. Biophys. Acta, 23, 480-489, 1957].

The role of electro-osmosis and dielectrophoresis in collection of micro/nano size particles in low frequency AC electric field

NASA Astrophysics Data System (ADS)

Wei, Chehung; Hsu, Che-Wei; Wang, Ching-Chieh

2007-09-01

The collecting and sorting micro size particles by electric force is easy to integrate with other bioassays. There are many forms of electric forces such as electrophoresis, dielectrophoresis and electroosmosis which can be used to manipulate particles. In an attempt to understand the role of electroosmosis and dielectrophoresis in the collection of micro size particles, a small device made of two parallel plates is used to study the particle movement under AC electric field. The device is fabricated by a top electrode and a bottom electrode separated by a spacer. The top electrode is made from an ITO glass where the bottom electrode is made of Corning 1737 glass sputtered with chromium. A dielectric layer is fabricated by spin coating a thin photo-resist (0.5~1μm) on the bottom electrode and a spacer made of curing PDMS is utilized to separate these electrodes. A 900μm × 900μm collecting chamber is fabricated on the bottom electrode via photolithography. The amine-modified polystyrene fluorescent particles whose average size is 1 μm were used for collection experiments. Different frequency and power were applied to generate the non-uniform electric field. It was found that frequency is the critical factor for electroosmotic velocity. There seems to be an optimum frequency that leads to largest particle velocity. The underlying mechanism is believed to the competing forces among dielectrophoresis and electroosmosis. This device demonstrates that the electroosmosis force is suitable for collecting bio-particles in AC electric field.

Automated characterization and assembly of individual nanowires for device fabrication.

PubMed

Yu, Kaiyan; Yi, Jingang; Shan, Jerry W

2018-05-15

The automated sorting and positioning of nanowires and nanotubes is essential to enabling the scalable manufacturing of nanodevices for a variety of applications. However, two fundamental challenges still remain: (i) automated placement of individual nanostructures in precise locations, and (ii) the characterization and sorting of highly variable nanomaterials to construct well-controlled nanodevices. Here, we propose and demonstrate an integrated, electric-field based method for the simultaneous automated characterization, manipulation, and assembly of nanowires (ACMAN) with selectable electrical conductivities into nanodevices. We combine contactless and solution-based electro-orientation spectroscopy and electrophoresis-based motion-control, planning and manipulation strategies to simultaneously characterize and manipulate multiple individual nanowires. These nanowires can be selected according to their electrical characteristics and precisely positioned at different locations in a low-conductivity liquid to form functional nanodevices with desired electrical properties. We validate the ACMAN design by assembling field-effect transistors (FETs) with silicon nanowires of selected electrical conductivities. The design scheme provides a key enabling technology for the scalable, automated sorting and assembly of nanowires and nanotubes to build functional nanodevices.

MOM3D method of moments code theory manual

NASA Technical Reports Server (NTRS)

Shaeffer, John F.

1992-01-01

MOM3D is a FORTRAN algorithm that solves Maxwell's equations as expressed via the electric field integral equation for the electromagnetic response of open or closed three dimensional surfaces modeled with triangle patches. Two joined triangles (couples) form the vector current unknowns for the surface. Boundary conditions are for perfectly conducting or resistive surfaces. The impedance matrix represents the fundamental electromagnetic interaction of the body with itself. A variety of electromagnetic analysis options are possible once the impedance matrix is computed including backscatter radar cross section (RCS), bistatic RCS, antenna pattern prediction for user specified body voltage excitation ports, RCS image projection showing RCS scattering center locations, surface currents excited on the body as induced by specified plane wave excitation, and near field computation for the electric field on or near the body.

Modeling Plasma Formation in a Micro-gap at Microwave Frequency

NASA Astrophysics Data System (ADS)

Bowman, Arthur; Remillard, Stephen

2013-03-01

In the presence of a strong electric field, gas molecules become ionized, forming a plasma. The study of this dielectric breakdown at microwave frequency has important applications in improving the operation of radio frequency (RF) devices, where the high electric fields present in small gaps can easily ionize gases like air. A cone and tuner resonant structure was used to induce breakdown of diatomic Nitrogen in adjustable micro-gaps ranging from 13 to 1,156 μm. The electric field for plasma formation exhibited strong pressure dependence in the larger gap sizes, as predicted by previous theoretical and experimental work. Pressure is proportional to the frequency of collision between electrons and molecules, which increases with pressure when the gap is large, but levels off in the micro-gap region. A separate model of the breakdown electric field based on the characteristic diffusion length of the plasma also fit the data poorly for these smaller gap sizes. This may be explained by a hypothesis that dielectric breakdown at and below the 100 μm gap size occurs outside the gap, an argument that is supported by the observation of very high breakdown threshold electric fields in this region. Optical emissions revealed that vibrational and rotational molecular transitions of the first positive electronic system are suppressed in micro-gaps, indicating that transitions into the molecular ground state do not occur in micro-gap plasmas. Acknowledgements: National Science Foundation under NSF-REU Grant No. PHY/DMR-1004811, the Provost's Office of Hope College, and the Hope College Division of Natural and Applied Sciences.

Dynamics of Ring Current and Electric Fields in the Inner Magnetosphere During Disturbed Periods: CRCM-BATS-R-US Coupled Model

NASA Technical Reports Server (NTRS)

Buzulukova, N.; Fok, M.-C.; Pulkkinen, A.; Kuznetsova, M.; Moore, T. E.; Glocer, A.; Brandt, P. C.; Toth, G.; Rastaetter, L.

2010-01-01

We present simulation results from a one-way coupled global MHD model (Block-Adaptive-Tree Solar-Wind Roe-Type Upwind Scheme, BATS-R-US) and kinetic ring current models (Comprehensive Ring Current Model, CRCM, and Fok Ring Current, FokRC). The BATS-R-US provides the CRCM/FokRC with magnetic field information and plasma density/temperature at the polar CRCM/FokRC boundary. The CRCM uses an electric potential from the BATS-R-US ionospheric solver at the polar CRCM boundary in order to calculate the electric field pattern consistent with the CRCM pressure distribution. The FokRC electric field potential is taken from BATS-R-US ionospheric solver everywhere in the modeled region, and the effect of Region II currents is neglected. We show that for an idealized case with southward-northward-southward Bz IMF turning, CRCM-BATS-R-US reproduces well known features of inner magnetosphere electrodynamics: strong/weak convection under the southward/northward Bz; electric field shielding/overshielding/penetration effects; an injection during the substorm development; Subauroral Ion Drift or Polarization Jet (SAID/PJ) signature in the dusk sector. Furthermore, we find for the idealized case that SAID/PJ forms during the substorm growth phase, and that substorm injection has its own structure of field-aligned currents which resembles a substorm current wedge. For an actual event (12 August 2000 storm), we calculate ENA emissions and compare with Imager for Magnetopause-to-Aurora Global Exploration/High Energy Neutral Atom data. The CRCM-BATS-R-US reproduces both the global morphology of ring current and the fine structure of ring current injection. The FokRC-BATS-R-US shows the effect of a realistic description of Region II currents in ring current-MHD coupled models.

Tripolar electric field Structure in guide field magnetic reconnection

NASA Astrophysics Data System (ADS)

Fu, Song; Huang, Shiyong; Zhou, Meng; Ni, Binbin; Deng, Xiaohua

2018-03-01

It has been shown that the guide field substantially modifies the structure of the reconnection layer. For instance, the Hall magnetic and electric fields are distorted in guide field reconnection compared to reconnection without guide fields (i.e., anti-parallel reconnection). In this paper, we performed 2.5-D electromagnetic full particle simulation to study the electric field structures in magnetic reconnection under different initial guide fields (Bg). Once the amplitude of a guide field exceeds 0.3 times the asymptotic magnetic field B0, the traditional bipolar Hall electric field is clearly replaced by a tripolar electric field, which consists of a newly emerged electric field and the bipolar Hall electric field. The newly emerged electric field is a convective electric field about one ion inertial length away from the neutral sheet. It arises from the disappearance of the Hall electric field due to the substantial modification of the magnetic field and electric current by the imposed guide field. The peak magnitude of this new electric field increases linearly with the increment of guide field strength. Possible applications of these results to space observations are also discussed.

Effect Of Superfluidity And Differential Rotation Of Quark Matter On Magetic Field Evolution in Neutron Star And Black Hole

NASA Astrophysics Data System (ADS)

Aurongzeb, Deeder

2010-11-01

Anomalous X-ray pulsars and soft gamma-ray repeaters reveal that existence of very strong magnetic field(> 10e15G) from neutron stars. It has been estimated that at the core the magnitude can be even higher at the center. Apart from dynamo mechanism it has been shown that color locked ferromagnetic phase [ Phys. Rev. D. 72,114003(2005)] can be a possible origin of magnetic field. In this study, we explore electric charge of strange quark matter and its effect on forming chirality in the quark-gluon plasma. We show that electromagnetic current induced by chiral magnetic effect [(Phys. Rev. D. 78.07033(2008)] can induce differential rotation in super fluid quark-gluon plasma giving additional boost to the magnetic field. The internal phase and current has no effect from external magnetic field originating from active galactic nuclei due to superconducting phase formation which screens the fields due to Meissner effect. We show that differential motion can create high radial electric field at the surface making all radiation highly polarized and directional including thermal radiation. As the electric field strength can be even stronger for a collapsing neutron star, the implication of this study to detect radiation from black holes will also be discussed. The work was partly completed at the University of Texas at austin

Investigating Perturbation Electric Fields and Their Effects on the Coupled Low-, Mid- and High-latitude Ionosphere

DTIC Science & Technology

2015-08-14

stream (SAPS) E field had been strong. During these E field events, the repeated development of equatorial ionization anomaly ( EIA ), storm-enhanced...density (SED) bulge and SED plume occurred in those longitude sectors that covered the local dusk-midnight hours. Thus, a well-formed EIA - SED...Observational results and CTIPe simulated wind vector maps suggest that 1) the enhanced growth of the EIA transported solar produced plasma to the

Core-protective half-metallicity in trilayer graphene nanoribbons

NASA Astrophysics Data System (ADS)

Jeon, Gi Wan; Lee, Kyu Won; Lee, Cheol Eui

2017-07-01

Half-metals, playing an important role in spintronics, can be described as materials that enable fully spin-polarized electrical current. Taking place in graphene-based materials, half-metallicity has been shown in zigzag-edged graphene nanoribbons (ZGNRs) under an electric field. Localized electron states on the edge carbons are a key to enabling half-metallicity in ZGNRs. Thus, modification of the localized electron states is instrumental to the carbon-based spintronics. Our simple model shows that in a trilayer ZGNRs (triZGNRs) only the middle layer may become half-metallic leaving the outer layers insulating in an electric field, as confirmed by our density functional theory (DFT) calculations. Due to the different circumstances of the edge carbons, the electron energies at the edge carbons are different near the Fermi level, leading to a layer-selective half-metallicity. We believe that triZGNRs can be the tiniest electric cable (nanocable) form and can open a route to graphene-based spintronics applications.

Effect of cholesterol on electrostatics in lipid-protein films of a pulmonary surfactant.

PubMed

Finot, Eric; Leonenko, Yuri; Moores, Brad; Eng, Lukas; Amrein, Matthias; Leonenko, Zoya

2010-02-02

We report the changes in the electrical properties of the lipid-protein film of pulmonary surfactant produced by excess cholesterol. Pulmonary surfactant (PS) is a complex lipid-protein mixture that forms a molecular film at the interface of the lung's epithelia. The defined molecular arrangement of the lipids and proteins of the surfactant film gives rise to the locally highly variable electrical surface potential of the interface, which becomes considerably altered in the presence of cholesterol. With frequency modulation Kelvin probe force microscopy (FM-KPFM) and force measurements, complemented by theoretical analysis, we showed that excess cholesterol significantly changes the electric field around a PS film because of the presence of nanometer-sized electrostatic domains and affects the electrostatic interaction of an AFM probe with a PS film. These changes in the local electrical field would greatly alter the interaction of the surfactant film with charged species and would immediately impact the manner in which inhaled (often charged) airborne nanoparticles and fibers might interact with the lung interface.

Variability in electromagnetic field levels over time, and Monte-Carlo simulation of exposure parameters.

PubMed

Pachón-García, F T; Paniagua-Sánchez, J M; Rufo-Pérez, M; Jiménez-Barco, A

2014-12-01

This article analyses the electric field levels around medium-wave transmitters, delimiting the temporal variability of the levels received at a pre-established reception point. One extensively used dosimetric criterion is to consider historical levels of the field recorded over a certain period of time so as to provide an overall perspective of radio-frequency electric field exposure in a particular environment. This aspect is the focus of the present study, in which the measurements will be synthesised in the form of exposure coefficients. Two measurement campaigns were conducted: one short term (10 days) and the other long term (1 y). The short-term data were used to study which probability density functions best approximate the measured levels. The long-term data were used to compute the principal statistics that characterise the field values over a year. The data that form the focus of the study are the peak traces, since these are the most representative from the standpoint of exposure. The deviations found were around 6 % for short periods and 12 % for long periods. The information from the two campaigns was used to develop and implement a computer application based on the Monte Carlo method to simulate values of the field, allowing one to carry out robust statistics. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

PIC simulation of a thermal anisotropy-driven Weibel instability in a circular rarefaction wave

NASA Astrophysics Data System (ADS)

Dieckmann, M. E.; Sarri, G.; Murphy, G. C.; Bret, A.; Romagnani, L.; Kourakis, I.; Borghesi, M.; Ynnerman, A.; O'C Drury, L.

2012-02-01

The expansion of an initially unmagnetized planar rarefaction wave has recently been shown to trigger a thermal anisotropy-driven Weibel instability (TAWI), which can generate magnetic fields from noise levels. It is examined here whether the TAWI can also grow in a curved rarefaction wave. The expansion of an initially unmagnetized circular plasma cloud, which consists of protons and hot electrons, into a vacuum is modelled for this purpose with a two-dimensional particle-in-cell (PIC) simulation. It is shown that the momentum transfer from the electrons to the radially accelerating protons can indeed trigger a TAWI. Radial current channels form and the aperiodic growth of a magnetowave is observed, which has a magnetic field that is oriented orthogonal to the simulation plane. The induced electric field implies that the electron density gradient is no longer parallel to the electric field. Evidence is presented here that this electric field modification triggers a second magnetic instability, which results in a rotational low-frequency magnetowave. The relevance of the TAWI is discussed for the growth of small-scale magnetic fields in astrophysical environments, which are needed to explain the electromagnetic emissions by astrophysical jets. It is outlined how this instability could be examined experimentally.

Effects of microwave electric fields on the translational diffusion of dipolar molecules in surface potential: A simulation study

NASA Astrophysics Data System (ADS)

Kapranov, Sergey V.; Kouzaev, Guennadi A.

2018-01-01

Variations of effective diffusion coefficient of polar molecules exposed to microwave electric fields in a surface potential are studied by solving coupled stochastic differential equations of motion with a deterministic component of the surface force. Being an essential tool for the simulation interpretation, a theoretical approach to effective diffusion in surface potential is first developed. The effective diffusion coefficient is represented as the product of the normal diffusion coefficient and potential-dependent correction function, whose temperature dependence is close to the Arrhenius form. The analytically found zero-diffusion condition defines the state of thermal equilibrium at the surface. The diffusion of a water-like dipole molecule in the potential of graphite surface is simulated in the field-free conditions and in the presence of the alternating electric fields of various magnitude intensities and frequencies. Temperature dependence of the correction function exhibits field-induced variations of the effective Lennard-Jones energy parameter. It demonstrates maximum departure from the zero-field value at certain frequencies and intensities, which is associated with variations in the rotational dynamics. A concept of the amplitude-frequency resonance put forward to interpret the simulation results is explained using a heuristic reasoning and is corroborated by semi-quantitative considerations in terms of the Dissado-Hill cluster theory of dielectric relaxation.

Structural, electrical, optical and magneto-electric characteristics of chemically synthesized CaCu3Ti4O12 dielectric ceramics

NASA Astrophysics Data System (ADS)

Parida, Kalpana; Choudhary, R. N. P.

2017-07-01

CaCu3Ti4O12 (CCTO) was prepared by a chemical reaction method. The pellets prepared from the calcined powder of the material were sintered at 1100 °C. Analysis of x-ray diffraction pattern, recorded on CCTO powder, confirms the phase formation of CCTO. Studies of dielectric (ɛ r, tanδ) and impedance parameters using dielectric and impedance spectroscopy of the compound have provided information about the electrical properties and the dielectric relaxation mechanism of the material. Detailed studies on the variation of electrical conductivity (dc) with temperature show semi-conducting nature of the material. Study of frequency (of applied electric field) dependence of ac conductivity at different temperatures suggests that the compound follows the Jonscher’s power law. Complex impedance spectroscopic analysis suggests that the semicircles formed in the Nyquist plot are connected to the grains, grain boundary and interface effects. An optical energy band gap of ~1.9 eV is obtained from the UV-visible absorbance spectrum. The magnetic data related to magneto-electric (ME) coefficient, measured by varying dc bias magnetic field, have been obtained at room temperature.

Electrically Driven Liquid Film Boiling Experiment

NASA Technical Reports Server (NTRS)

Didion, Jeffrey R.

2016-01-01

This presentation presents the science background and ground based results that form the basis of the Electrically Driven Liquid Film Boiling Experiment. This is an ISS experiment that is manifested for 2021. Objective: Characterize the effects of gravity on the interaction of electric and flow fields in the presence of phase change specifically pertaining to: a) The effects of microgravity on the electrically generated two-phase flow. b) The effects of microgravity on electrically driven liquid film boiling (includes extreme heat fluxes). Electro-wetting of the boiling section will repel the bubbles away from the heated surface in microgravity environment. Relevance/Impact: Provides phenomenological foundation for the development of electric field based two-phase thermal management systems leveraging EHD, permitting optimization of heat transfer surface area to volume ratios as well as achievement of high heat transfer coefficients thus resulting in system mass and volume savings. EHD replaces buoyancy or flow driven bubble removal from heated surface. Development Approach: Conduct preliminary experiments in low gravity and ground-based facilities to refine technique and obtain preliminary data for model development. ISS environment required to characterize electro-wetting effect on nucleate boiling and CHF in the absence of gravity. Will operate in the FIR - designed for autonomous operation.

Thermal and electrical transport across a magnetic quantum critical point.

PubMed

Pfau, Heike; Hartmann, Stefanie; Stockert, Ulrike; Sun, Peijie; Lausberg, Stefan; Brando, Manuel; Friedemann, Sven; Krellner, Cornelius; Geibel, Christoph; Wirth, Steffen; Kirchner, Stefan; Abrahams, Elihu; Si, Qimiao; Steglich, Frank

2012-04-25

A quantum critical point (QCP) arises when a continuous transition between competing phases occurs at zero temperature. Collective excitations at magnetic QCPs give rise to metallic properties that strongly deviate from the expectations of Landau's Fermi-liquid description, which is the standard theory of electron correlations in metals. Central to this theory is the notion of quasiparticles, electronic excitations that possess the quantum numbers of the non-interacting electrons. Here we report measurements of thermal and electrical transport across the field-induced magnetic QCP in the heavy-fermion compound YbRh(2)Si(2) (refs 2, 3). We show that the ratio of the thermal to electrical conductivities at the zero-temperature limit obeys the Wiedemann-Franz law for magnetic fields above the critical field at which the QCP is attained. This is also expected for magnetic fields below the critical field, where weak antiferromagnetic order and a Fermi-liquid phase form below 0.07 K (at zero field). At the critical field, however, the low-temperature electrical conductivity exceeds the thermal conductivity by about 10 per cent, suggestive of a non-Fermi-liquid ground state. This apparent violation of the Wiedemann-Franz law provides evidence for an unconventional type of QCP at which the fundamental concept of Landau quasiparticles no longer holds. These results imply that Landau quasiparticles break up, and that the origin of this disintegration is inelastic scattering associated with electronic quantum critical fluctuations--these insights could be relevant to understanding other deviations from Fermi-liquid behaviour frequently observed in various classes of correlated materials.

Wear forms of heterogeneous electro-rheological fluids working in a hydraulic clutch system

NASA Astrophysics Data System (ADS)

Ziabska, E.; Duchowski, J.; Olszak, A.; Osowski, K.; Kesy, A.; Kesy, Z.; Choi, S. B.

2017-09-01

The paper presents experimental results concerning the wear of heterogeneous electro-rheological (ER) fluids operating as working fluids in a complex clutch system consisting of a hydrodynamic clutch and a cylinder viscous clutch. The change of electric field intensity in the clutches results in change of sheer stress values in working fluids what causes the change of transmitted torque. This work shows that the most important factors affecting the wear of the ER fluid are the electric field of high intensity, the accompanying electrical breakdown, and the high temperature of the silicone oil. In addition, the water from the humid air absorbed mainly by hygroscopic particles influences a significant impact on the wear of the working fluid. Various forms of wear particles of the fluid depending on the prevailing conditions such as working mode are observed from the microscopic aspects. It is observed that the particles are flattened, rolled out or smashed into smaller fragments, partially melted, wrinkled and glued or caked. In addition, it is identified that the partial destruction of silicone oil is occurred due to the damage of the hydrocarbon chains, as evidenced by the decrease in its viscosity and the presence of the particle matter newly containing silicon.

Effect of Induced Charge Electroosmosis on the Dielectrophoretic Motion of Particles

NASA Astrophysics Data System (ADS)

Swaminathan, T.; Hu, Howard

2006-11-01

Most suspensions involve the formation of ionic double layers next to the surface of particles due to the induced-charge on the surface. These double layers affect the motion of the particle even under AC electric fields. They modify the net dipole moment of the particle and at the same time produce slip velocities on the surfaces of these particles. A method to numerically evaluate the effect of the double layer on the dielectrophoretic motion of particles has been previously developed to study these two effects. The technique involves a matched asymptotic expansion of the electric field near the particle surface, where the double layer is formed, and is written as a jump-boundary-condition for the electric potential when the thickness of the double layer is small compared to the size of the particle. The developed jump-boundary-condition is then used to calculate an effective zeta potential on the particle surface. Unlike classical electroosmosis, this zeta potential is no longer constant on every part of the surface and is dependent on the applied electric field. The effect of the induced-charge electroosmotic slip velocity on the dielectrophoretic motion of particles has been observed using this technique.

Electrical manipulation of glycan-phosphatidyl inositol-tethered proteins in planar supported bilayers.

PubMed Central

Groves, J T; Wülfing, C; Boxer, S G

1996-01-01

Electric fields have been used to manipulate and concentrate glycan-phosphatidyl inositol (GPI)-tethered proteins in planar supported bilayers. Naturally GPI-linked CD48, along with engineered forms of I-Ek and B7-2, in which their transmembrane domains have been genetically replaced with the GPI linkage, were studied. The proteins were labeled with fluorescently tagged antibodies, allowing the electric field-induced behavior to be followed by epifluorescence microscopy. All three protein complexes were observed to migrate toward the cathode with the B7-2 and CD48, each tethered to the membrane by a single GPI linker, moving significantly faster than the I-Ek, which has two GPI linkers. Patterns scratched into the membrane function as barriers to lateral diffusion and were used to isolate the proteins into highly concentrated corrals. All field-induced concentration profiles were completely reversible, indicating that the supported bilayer provides a stable, fluid environment in which GPI-tethered proteins can be manipulated. The ability to electrically control the spatial distribution of membrane-tethered proteins provides new opportunities for the study of biological membranes and the development of membrane-based devices. Images FIGURE 2 FIGURE 3 FIGURE 4 FIGURE 5 FIGURE 6 PMID:8913608

Streamer development in barrier discharge in air: spectral signatures and electric field

NASA Astrophysics Data System (ADS)

Hoder, Tomas; Simek, Milan; Bonaventura, Zdenek; Prukner, Vaclav

2015-09-01

Electrical breakdown in the upper atmosphere takes form of so called Transient Luminous Events (TLE). Down to the certain pressure limit, the first phases of the TLE-phenomena are controlled by the streamer mechanism. In order to understand the development of these events, streamers in 10 torr air were generated in volume barrier discharge. Stability and reproducibility of generated streamers were secured by proper electrode geometry and specific applied voltage waveform. In this work, spectrally resolved measurements of the streamer head emission with high spatial and temporal resolution are presented. Precise recordings of the emission of the second positive and first negative systems of molecular nitrogen allowed the determination of the spatio-temporal development of the reduced electric field in the streamer head. This unique experimental result reveals in more details the early stages of the streamer development and gives, besides values for streamer velocity and its diameter, quantitative information on the magnitude of the electric field. T.H. was financed through the ESF Programme TEA-IS (Grant No. 4219), M.S. and V.P. by the AVCR under collaborative project M100431201 and Z.B. acknowledges the support of grant of Czech Science Foundation GA15-04023S.

An Overview of the Efficacy of a Next Generation Electroceutical Wound Care Device.

PubMed

Kim, Hosan; Park, Soon; Housler, Greggory; Marcel, Vanessa; Cross, Sue; Izadjoo, Mina

2016-05-01

Novel approaches including nonpharmacological methodologies for prevention and control of microbial pathogens and emerging antibiotic resistance are urgently needed. Procellera is a wound care device consisting of a matrix of alternating silver (Ag) and zinc (Zn) dots held in position on a polyester substrate with a biocompatible binder. This electroceutical medical device is capable of generating a direct current voltage (0.5-0.9 Volts). Wound dressings containing metals such as Ag and/or Zn as active ingredients are being used for control of colonized and infected wounds. Reports on the presence of electric potential field across epithelium and wound current on wounding have shown that wound healing is enhanced in the presence of an external electrical field. However, majority of the electrical devices require an external power source for delivering pulsed or continuous electric power at the wound site. A microelectric potential-generating system without an external power source is an ideal treatment modality for application in both clinical and field settings. The research presented herein describes efficacy evaluation of a wireless bioelectric dressing against both planktonic and biofilm forms of wound pathogens including multidrug resistant organisms. Reprint & Copyright © 2016 Association of Military Surgeons of the U.S.

Vibration damping of elastic waves in electrically conducting media subjected to high magnetic fields

NASA Technical Reports Server (NTRS)

Horwath, T. G.

1992-01-01

The propagation of vibrational energy in bulk, torsional, and flexural modes, in electrically conducting media can undergo strong attenuation if subjected to high magnetic fields in certain spatial arrangements. The reasons for this are induced Eddy currents which are generated by the volume elements in the media moving transversally to the magnetic field at acoustic velocities. In magnetic fields achievable with superconductors, the non-conservative (dissipative) forces are compared to the elastic and inertial forces for most metals. Strong dissipation of vibrational energy in the form of heat takes place as a result. A simplified theory is presented based on engineering representations of electrodynamics, attenuation values for representative metals are calculated, and problems encountered in formulating a generalized theory based on electrodynamics of moving media are discussed. General applications as well as applications specific to maglev are discussed.

Kinetic theory for electrostatic waves due to transverse velocity shears

NASA Technical Reports Server (NTRS)

Ganguli, G.; Lee, Y. C.; Palmadesso, P. J.

1988-01-01

A kinetic theory in the form of an integral equation is provided to study the electrostatic oscillations in a collisionless plasma immersed in a uniform magnetic field and a nonuniform transverse electric field. In the low temperature limit the dispersion differential equation is recovered for the transverse Kelvin-Helmholtz modes for arbitrary values of K parallel, where K parallel is the component of the wave vector in the direction of the external magnetic field assumed in the z direction. For higher temperatures the ion-cyclotron-like modes described earlier in the literature by Ganguli, Lee and Plamadesso are recovered. In this article, the integral equation is reduced to a second-order differential equation and a study is made of the kinetic Kelvin-Helmholtz and ion-cyclotron-like modes that constitute the two branches of oscillation in a magnetized plasma including a transverse inhomogeneous dc electric field.

Use of an electric field in an electrostatic liquid film radiator.

PubMed

Bankoff, S G; Griffing, E M; Schluter, R A

2002-10-01

Experimental and numerical work was performed to further the understanding of an electrostatic liquid film radiator (ELFR) that was originally proposed by Kim et al.(1) The ELFR design utilizes an electric field that exerts a normal force on the interface of a flowing film. The field lowers the pressure under the film in a space radiator and, thereby, prevents leakage through a puncture in the radiator wall. The flowing film is subject to the Taylor cone instability, whereby a cone of fluid forms underneath an electrode and sharpens until a jet of fluid is pulled toward the electrode and disintegrates into droplets. The critical potential for the instability is shown to be as much as an order of magnitude higher than that used in previous designs.(2) Furthermore, leak stoppage experiments indicate that the critical field is adequate to stop leaks in a working radiator.

Low-Loss and Broadband Metamaterials for Negative Index and Transformational Optics Applications

DTIC Science & Technology

2012-05-22

the temporal electric field, multiplying by ǫ(ω), and then inverse Fourier transforming the result. The quantities ∂wE/∂t and ∂qE/∂t were formed...force occurs in a material with gain. Imaging and antenna opportunities are described for metal-insulator stack lenses, and analytic models are...and Transformational Optics Applications Award Number: W911NF-10-1-0492 Kevin J. Webb School of Electrical and Computer Engineering Purdue University

Electron Acceleration in the Magnetotail during Substorms in Semi-Global PIC Simulations

NASA Astrophysics Data System (ADS)

Richard, R. L.; Schriver, D.; Ashour-Abdalla, M.; El-Alaoui, M.; Lapenta, G.; Walker, R. J.

2015-12-01

To understand the acceleration of electrons during a substorm reconnection event we have applied a semi-global particle in cell (PIC) simulation box embedded within a global magnetohydrodynamic (MHD) simulation of Earth's magnetosphere for an event on February 15, 2008. The MHD results were used to populate the PIC simulation and to set the boundary conditions. In the magnetotail we found that a series of dipolarizations formed due to unsteady reconnection. We also found that the most energetic electrons were in the separatrices far from the x-point. We attributed the acceleration to a streaming instability in the separatrices. To further understand electron acceleration we have applied the large scale kinetic (LSK) technique in which tens- to hundreds- of thousands of electrons are followed within the electric and magnetic fields from the PIC simulations., Electrons are already included in the PIC simulation, but the LSK simulations will allow selected individual particles to be followed and analyzed. Initially we performed electron LSK calculations in a two dimensional version of the PIC simulation in which electrons were allowed to move in the ignorable cross tail direction. These LSK calculations showed that electrons gained energy primarily for two reasons: (1) acceleration by the average dawn to dusk electric field and (2) acceleration by intense but localized electric field structures. The overall electron transport was more dawnward than duskward due to the average electric field. At the same time electrons typically moved away from the reconnection region in both the earthward and tailward directions. Superimposed on this large-scale transport was motion in both the dusk and dawn directions across the tail because of the electric field structures, which were particularly intense in the separatrices. LSK calculations are now being carried out by using the full three-dimensional magnetic and electric fields from the PIC simulation and these results will be compared with the two-dimensional results for the same substorm event.

High-beta spherical tokamak startup in TS-4 merging experiment by use of toroidal field ramp-up

NASA Astrophysics Data System (ADS)

Kaminou, Yasuhiro; , Toru, II; Kato, Joji; Inomoto, Michiaki; Ono, Yasushi; TS Group Team; National InstituteFusion Science Collaboration

2014-10-01

We demonstrated the formation method of an ultrahigh-beta spherical tokamak by use of a field-reversed configuration and a spheromak in TS-4 device (R ~ 0.5 m, A ~ 1.5, Ip ~ 30-100 kA, B ~ 100 mT). This method is composed of the following steps: 1. Two spheromaks are merged together and a high-beta spheromak or FRC is formed by reconnection heating. 2. External toroidal magnetic field is added (current rising time ~50 μs), and spherical tokamak-like configuration is formed. In this way, the ultrahigh-beta ST is formed. The ultrahigh-beta ST formed by FRC has a diamagnetic toroidal field, and it presumed to be in a second-stable state for ballooning stability, and the one formed by spheromak has a weak paramagnetic toroidal magnetic field, while a spheormak has a strong paramagnetic toroidal magnetic field. This diamagnetic current derives from inductive electric field by ramping up the external toroidal magnetic field, and the diamagnetic current sustains high thermal pressure of the ultrahigh-beta spherical tokamak. And the beta of the ultrahigh-beta ST formed by FRC reaches about 50%. To sustain the high-beta state, 0.6 MW neutral beam injection and center solenoid coils are installed to the TS-4 device. In the poster, we report the experimental results of ultrahigh-beta spherical tokamak startup and sustainment by NBI and CS current driving experiment.

Structure of the screening layer near a plane isolated body in the deep vacuum. Part 2. Monoenergetic isotropic flow

NASA Astrophysics Data System (ADS)

Gunko, Yuri F.; Gunko, Natalia A.

2018-05-01

In this paper we consider the problem of determining the structure of the electric field near the surface of a flat insulated body under conditions of a deep vacuum. It is assumed that the emitted particles are electrons leaving the body surface under the influence of ionizing radiation whose velocities distribution near the surface is isotropic. It is estimated the thickness of the screening layer under conditions of stationary emission from a flat surface. The solutio of the problem of determining a stationary self-consistent electric field near the surface is found in a simple analytical form. The thickness of the screening layer is calculated from this formula.

ELF wave production by an electron beam emitting rocket system and its suppression on auroral field lines - Evidence for Alfven and drift waves

NASA Astrophysics Data System (ADS)

Winckler, J. R.; Erickson, K. N.; Abe, Y.; Steffen, J. E.; Malcolm, P. R.

1985-07-01

Orthogonal probes on a free-flying plasma diagnostics payload are used to study ELF electric disturbances in the auroral ionosphere that are due to the injection of powerful electron beams. Frequency spectrograms are presented for various pitch angles, pulsing characteristics, and other properties of the injected beams; the large scale DC ionospheric convection electric field is measured, together with auroral particle precipitation, visual auroral forms, and ionospheric parameters. In view of the experimental results obtained, it is postulated that the observed ELF waves are in the Alfven and drift modes, and are generated by the positive vehicle potential during beam injection.

Theory of Carbon Nanotube (CNT)-Based Electron Field Emitters

PubMed Central

Bocharov, Grigory S.; Eletskii, Alexander V.

2013-01-01

Theoretical problems arising in connection with development and operation of electron field emitters on the basis of carbon nanotubes are reviewed. The physical aspects of electron field emission that underlie the unique emission properties of carbon nanotubes (CNTs) are considered. Physical effects and phenomena affecting the emission characteristics of CNT cathodes are analyzed. Effects given particular attention include: the electric field amplification near a CNT tip with taking into account the shape of the tip, the deviation from the vertical orientation of nanotubes and electrical field-induced alignment of those; electric field screening by neighboring nanotubes; statistical spread of the parameters of the individual CNTs comprising the cathode; the thermal effects resulting in degradation of nanotubes during emission. Simultaneous consideration of the above-listed effects permitted the development of the optimization procedure for CNT array in terms of the maximum reachable emission current density. In accordance with this procedure, the optimum inter-tube distance in the array depends on the region of the external voltage applied. The phenomenon of self-misalignment of nanotubes in an array has been predicted and analyzed in terms of the recent experiments performed. A mechanism of degradation of CNT-based electron field emitters has been analyzed consisting of the bombardment of the emitters by ions formed as a result of electron impact ionization of the residual gas molecules. PMID:28348342

Ferroelectric polarization induces electric double layer bistability in electrolyte-gated field-effect transistors.

PubMed

Fabiano, Simone; Crispin, Xavier; Berggren, Magnus

2014-01-08

The dense surface charges expressed by a ferroelectric polymeric thin film induce ion displacement within a polyelectrolyte layer and vice versa. This is because the density of dipoles along the surface of the ferroelectric thin film and its polarization switching time matches that of the (Helmholtz) electric double layers formed at the ferroelectric/polyelectrolyte and polyelectrolyte/semiconductor interfaces. This combination of materials allows for introducing hysteresis effects in the capacitance of an electric double layer capacitor. The latter is advantageously used to control the charge accumulation in the semiconductor channel of an organic field-effect transistor. The resulting memory transistors can be written at a gate voltage of around 7 V and read out at a drain voltage as low as 50 mV. The technological implication of this large difference between write and read-out voltages lies in the non-destructive reading of this ferroelectric memory.

Joule heating effects on particle immobilization in insulator-based dielectrophoretic devices.

PubMed

Gallo-Villanueva, Roberto C; Sano, Michael B; Lapizco-Encinas, Blanca H; Davalos, Rafael V

2014-02-01

In this work, the temperature effects due to Joule heating obtained by application of a direct current electric potential were investigated for a microchannel with cylindrical insulating posts employed for insulator-based dielectrophoresis. The conductivity of the suspending medium, the local electric field, and the gradient of the squared electric field, which directly affect the magnitude of the dielectrophoretic force exerted on particles, were computationally simulated employing COMSOL Multiphysics. It was observed that a temperature gradient is formed along the microchannel, which redistributes the conductivity of the suspending medium leading to an increase of the dielectrophoretic force toward the inlet of the channel while decreasing toward the outlet. Experimental results are in good agreement with simulations on the particle-trapping zones anticipated. This study demonstrates the importance of considering Joule heating effects when designing insulator-based dielectrophoresis systems. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrically and spatially controllable PDLC phase gratings for diffraction and modulation of laser beams

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

Hadjichristov, Georgi B., E-mail: georgibh@issp.bas.bg; Marinov, Yordan G.; Petrov, Alexander G.

2016-03-25

We present a study on electrically- and spatially-controllable laser beam diffraction, electrooptic (EO) phase modulation, as well as amplitude-frequency EO modulation by single-layer microscale polymer-dispersed liquid crystal (PDLC) phase gratings (PDLC SLPGs) of interest for device applications. PDLC SLPGs were produced from nematic liquid crystal (LC) E7 in photo-curable NOA65 polymer. The wedge-formed PDLC SLPGs have a continuously variable thickness (2–25 µm). They contain LC droplets of diameters twice as the layer thickness, with a linear-gradient size distribution along the wedge. By applying alternating-current (AC) electric field, the PDLC SLPGs produce efficient: (i) diffraction splitting of transmitted laser beams; (ii)more » spatial redistribution of diffracted light intensity; (iii) optical phase modulation; (iv) amplitude-frequency modulation, all controllable by the driven AC field and the droplet size gradient.« less

Numerical simulation of a helical shape electric arc in the external axial magnetic field

NASA Astrophysics Data System (ADS)

Urusov, R. M.; Urusova, I. R.

2016-10-01

Within the frameworks of non-stationary three-dimensional mathematical model, in approximation of a partial local thermodynamic equilibrium, a numerical calculation was made of characteristics of DC electric arc burning in a cylindrical channel in the uniform external axial magnetic field. The method of numerical simulation of the arc of helical shape in a uniform external axial magnetic field was proposed. This method consists in that that in the computational algorithm, a "scheme" analog of fluctuations for electrons temperature is supplemented. The "scheme" analogue of fluctuations increases a weak numerical asymmetry of electrons temperature distribution, which occurs randomly in the course of computing. This asymmetry can be "picked up" by the external magnetic field that continues to increase up to a certain value, which is sufficient for the formation of helical structure of the arc column. In the absence of fluctuations in the computational algorithm, the arc column in the external axial magnetic field maintains cylindrical axial symmetry, and a helical form of the arc is not observed.

Intrinsic electric fields and proton diffusion in immobilized protein membranes. Effects of electrolytes and buffers.

PubMed Central

Zabusky, N J; Deem, G S

1979-01-01

We present a theory for proton diffusion through an immobilized protein membrane perfused with an electrolyte and a buffer. Using a Nernst-Planck equation for each species and assuming local charge neutrality, we obtain two coupled nonlinear diffusion equations with new diffusion coefficients dependent on the concentration of all species, the diffusion constants or mobilities of the buffers and salts, the pH-derivative of the titration curves of the mobile buffer and the immobilized protein, and the derivative with respect to ionic strength of the protein titration curve. Transient time scales are locally pH-dependent because of protonation-deprotonation reactions with the fixed protein and are ionic strength-dependent because salts provide charge carriers to shield internal electric fields. Intrinsic electric fields arise proportional to the gradient of an "effective" charge concentration. The field may reverse locally if buffer concentrations are large (greater to or equal to 0.1 M) and if the diffusivity of the electrolyte species is sufficiently small. The "ideal" electrolyte case (where each species has the same diffusivity) reduces to a simple form. We apply these theoretical considerations to membranes composed of papain and bovine serum albumin (BSA) and show that intrinsic electric fields greatly enhance the mobility of protons when the ionic strength of the salts is smaller than 0.1 M. These results are consistent with experiments where pH changes are observed to depend strongly on buffer, salt, and proton concentrations in baths adjacent to the membranes. PMID:233570

Photonic crystal wave guide for non-cryogenic cooled carbon nanotube based middle wave infrared sensors

NASA Astrophysics Data System (ADS)

Fung, Carmen Kar Man; Xi, Ning; Lou, Jianyong; Lai, King Wai Chiu; Chen, Hongzhi

2010-10-01

We report high sensitivity carbon nanotube (CNT) based middle wave infrared (MWIR) sensors with a two-dimensional photonic crystal waveguide. MWIR sensors are of great importance in a variety of current military applications including ballistic missile defense, surveillance and target detection. Unlike other existing MWIR sensing materials, CNTs exhibit low noise level and can be used as new nano sensing materials for MWIR detection where cryogenic cooling is not required. However, the quantum efficiency of the CNT based infrared sensor is still limited by the small sensing area and low incoming electric field. Here, a photonic nanostructure is used as a resonant cavity for boosting the electric field intensity at the position of the CNT sensing element. A two-dimensional photonic crystal with periodic holes in a polymer thin film is fabricated and a resonant cavity is formed by removing holes from the array of the photonic crystal. Based on the design of the photonic crystal topologies, we theoretically study the electric field distribution to predict the resonant behavior of the structure. Numerical simulations reveal the field is enhanced and almost fully confined to the defect region of the photonic crystal. To verify the electric field enhancement effect, experiments are also performed to measure the photocurrent response of the sensor with and without the photonic crystal resonant cavity. Experimental results show that the photocurrent increases ~3 times after adding the photonic crystal resonant cavity.

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

Jimbert, P.; Fernandez, J. I.; Eguia, I.

It is well known that one of the main advantages of the high speed forming (HSF) processes is the improvement in the forming limits of the used materials.Using the Electromagnetic Forming (EMF) technology two materials have been tested with different mechanical and physical properties: the AA5754 aluminium and the AZ31B magnesium alloys.The EMF process principle can be described as follows: A significant amount of electrical energy is stored in a bank of capacitors which are suddenly discharged releasing all the stored energy. This electric discharge runs through a coil which generates an intense transient magnetic field. At the same timemore » transient Eddy currents are induced in the electrically conductive part placed some millimetres far from the coil. Another intense magnetic field is generated due to those Eddy currents but on the opposite direction as the one generated by the coil. A big magnetic repulsion force is created between the part and the coil. This magnetic repulsion between both fields is used to launch the blank with no physical contact and obtain the desired deformation on it.The Forming Limit Diagrams (FLD) obtained in the EMF experiments were them compared to the ones obtained with the 'Nakazima' method at conventional deformation speed for both alloys. In parallel to these physical experiments, some simulations were carried out. But trying to simulate this process by FEM is a though work. There are several physics and many factors to take into account in a few microseconds deformation process. And all these factors are tightly related with each other, that is why to this date there is no commercial software able to simulate the EMF process accurately.From LABEIN-Tecnalia we are working with to different softwares to simulate the whole process: Maxwell 3D for the electromagnetic part and PAM-STAMP2G for the mechanical part of the problem.« less

Wireless Electrical Device Using Open-Circuit Elements Having No Electrical Connections

NASA Technical Reports Server (NTRS)

Taylor, Bryant Douglas (Inventor); Woodard, Stanley E. (Inventor)

2012-01-01

A wireless electrical device includes an electrically unconnected electrical conductor and at least one electrically unconnected electrode spaced apart from the electrical conductor. The electrical conductor is shaped for storage of an electric field and a magnetic field. In the presence of a time-varying magnetic field, the electrical conductor so-shaped resonates to generate harmonic electric and magnetic field responses. Each electrode is at a location lying within the magnetic field response so-generated and is constructed such that a linear movement of electric charges is generated in each electrode due to the magnetic field response so-generated.

Static electric fields modify the locomotory behaviour of cockroaches.

PubMed

Jackson, Christopher W; Hunt, Edmund; Sharkh, Suleiman; Newland, Philip L

2011-06-15

Static electric fields are found throughout the environment and there is growing interest in how electric fields influence insect behaviour. Here we have analysed the locomotory behaviour of cockroaches (Periplaneta americana) in response to static electric fields at levels equal to and above those found in the natural environment. Walking behaviour (including velocity, distance moved, turn angle and time spent walking) were analysed as cockroaches approached an electric field boundary in an open arena, and also when continuously exposed to an electric field. On approaching an electric field boundary, the greater the electric field strength the more likely a cockroach would be to turn away from, or be repulsed by, the electric field. Cockroaches completely exposed to electric fields showed significant changes in locomotion by covering less distance, walking slowly and turning more often. This study highlights the importance of electric fields on the normal locomotory behaviour of insects.

Space weather effects on ground based technology

NASA Astrophysics Data System (ADS)

Clark, T.

Space weather can affect a variety of forms of ground-based technology, usually as a result of either the direct effects of the varying geomagnetic field, or as a result of the induced electric field that accompanies such variations. Technologies affected directly by geomagnetic variations include magnetic measurements made d ringu geophysical surveys, and navigation relying on the geomagnetic field as a direction reference, a method that is particularly common in the surveying of well-bores in the oil industry. The most obvious technology affected by induced electric fields during magnetic storms is electric power transmission, where the example of the blackout in Quebec during the March 1989 magnetic storm is widely known. Additionally, space weather effects must be taken into account in the design of active cathodic protection systems on pipelines to protect them against corrosion. Long-distance telecommunication cables may also have to be designed to cope with space weather related effects. This paper reviews the effects of space weather in these different areas of ground-based technology, and provides examples of how mitigation against hazards may be achieved. (The paper does not include the effects of space weather on radio communication or satellite navigation systems).

Electrical switching of an antiferromagnet

NASA Astrophysics Data System (ADS)

Jungwirth, Tomas

Louis Néel pointed out in his Nobel lecture that while abundant and interesting from theoretical viewpoint, antiferromagnets did not seem to have any applications. Indeed, the alternating directions of magnetic moments on individual atoms and the resulting zero net magnetization make antiferromagnets hard to control by tools common in ferromagnets. Strong coupling would be achieved if the externally generated field had a sign alternating on the scale of a lattice constant at which moments alternate in AFMs. However, generating such a field has been regarded unfeasible, hindering the research and applications of these abundant magnetic materials. We have recently predicted that relativistic quantum mechanics may offer staggered current induced fields with the sign alternating within the magnetic unit cell which can facilitate a reversible switching of an antiferromagnet by applying electrical currents with comparable efficiency to ferromagnets. Among suitable materials is a high Néel temperature antiferromagnet, tetragonal-phase CuMnAs, which we have recently synthesized in the form of single-crystal epilayers structurally compatible with common semiconductors. We demonstrate electrical writing and read-out, combined with the insensitivity to magnetic field perturbations, in a proof-of-concept antiferromagnetic memory device. We acknowledge support from European Research Council Advanced Grant No. 268066.

Low reflection and field localization over surface plasmon device with subwavelength patterned aluminum film

NASA Astrophysics Data System (ADS)

Yuan, Ying; Peng, Sha; Long, Huabao; Liu, Runhan; Wei, Dong; Zhang, Xinyu; Wang, Haiwei; Xie, Changsheng

2018-02-01

In this paper, we propose a new device composed of patterned sub-wavelength arrays to investigate surface plasmons (SPs) over sub-wavelength metal nano-structures. The device consists of silicon substrate and sub-wavelength patterns fabricated on a layer of aluminum film with nanometer thickness. Each sub-wavelength pattern formed in aluminum film is composed of a basic nano-square and twelve triangles for shaping single nano-pattern, which are uniformly distributed on the four sides of each square. Reflectance spectra and electric field distribution in infrared region are simulated. Numerical simulation results demonstrate that the device can efficiently lower its reflectance in infrared spectrum, and the response frequency can be controlled by only changing the device parameters such as square side length and then triangle vertex angle. Besides, the simulated electric field distribution of the device shows obviously field localization effect at the edges of aluminum film nano-structure. The electric filed around the tips of aluminum triangles is localized into sub-wavelength scale, so as to be beyond the common diffraction limitation. Our work will help to reveal the interesting properties of SPs device, and also bring new prospect of photonic device.

Nikola Tesla: the man behind the magnetic field unit.

PubMed

Roguin, Ariel

2004-03-01

The magnetic field strength of both the magnet and gradient coils used in MR imaging equipment is measured in Tesla units, which are named for Nikola Tesla. This article presents the life and achievements of this Serbian-American inventor and researcher who discovered the rotating magnetic field, the basis of most alternating-current machinery. Nikola Tesla had 700 patents in the United States and Europe that covered every aspect of science and technology. Tesla's discoveries include the Tesla coil, AC electrical conduction, improved lighting, newer forms of turbine engines, robotics, fluorescent light, wireless transmission of electrical energy, radio, remote control, discovery of cosmic radio waves, and the use of the ionosphere for scientific purposes. He was a genius whose discoveries had a pivotal role in advancing us into the modern era. Copyright 2004 Wiley-Liss, Inc.

Alignment of carbon iron into polydimethylsiloxane to create conductive composite with low percolation threshold and high piezoresistivity: experiment and simulation

NASA Astrophysics Data System (ADS)

Dong, Shuai; Wang, Xiaojie

2017-04-01

In this study, various amounts of carbonyl iron particles (CIPs) were cured into polydimethylsiloxane (PDMS) matrix under a magnetic field up to 1.0 T to create anisotropy of conductive composite materials. The electrical resistivity for the longitudinal direction was measured as a function of filler volume fraction to understand the electrical percolation behavior. The electrical percolation threshold (EPT) of CIPs-PDMS composite cured under a magnetic field can be as low as 0.1 vol%, which is much less than most of those studies in particulate composites. Meanwhile, the effects of compressive strain on the electrical properties of CIPs-PDMS composites were also investigated. The strain sensitivity depends on filler volume fraction and decreases with the increasing of compressive strain. It has been found that the composites containing a small amount of CI particles curing under a magnetic field exhibit a high strain sensitivity of over 150. Based on the morphological observation of the composite structures, a two-dimensional stick percolation model for the CIPs-PDMS composites has been established. The Monte Carlo simulation is performed to obtain the percolation probability. The simulation results in prediction of the values of EPTs are close to that of experimental measurements. It demonstrates that the low percolation behavior of CIPs-PDMS composites is due to the average length of particle chains forming by external magnetic field.

REACTION PRODUCTS FROM THE CHLORINATION OF SEAWATER. CHAPTER 34

EPA Science Inventory

Much of the present information on the products formed when seawater is chlorinated is based on observations of laboratory experiments in which chlorine was added to seawater to stimulate conditions of electricity generating plants. Results are reported for a field study at the P...

Diffractive Hyperbola of a Skin Layer

NASA Astrophysics Data System (ADS)

Yakubov, V. P.; Vaiman, E. V.; Shipilov, S. È.; Prasath, A. K.

2018-03-01

Based on an analysis of physics of the phase transition from the quasistatic state field to the running wave field of elementary electric and magnetic dipoles located in absorbing media, it is concluded that the skin layer is formed at the boundary of this phase transition. The possibility is considered of obtaining the diffractive hyperbola of the skin layer and its subsequent application for sensing of objects in strongly absorbing media.

Effects of Pulsed Electric Fields (PEF) on Vitamin C and Its Antioxidant Properties.

PubMed

Zhang, Zhi-Hong; Zeng, Xin-An; Brennan, Charles S; Brennan, Margaret; Han, Zhong; Xiong, Xia-Yu

2015-10-13

In this study, pulsed electric fields (PEF) treatments and their effects on the structure of vitamin C (VIT-C) were estimated by fluorescence and Fourier transform infrared (FT-IR) spectroscopy, the relative content of VIT-C was measured by HPLC and the antioxidant properties of treated VIT-C by DPPH radical scavenging as well as reducing power tests. The fluorescence intensity of treated VIT-C increased slightly compared to the untreated VIT-C. Moreover, the effect of PEF on the structure of VIT-C was observed using the FT-IR spectra. These phenomena indicated that the PEF affected the conformation of VIT-C, which promoted the VIT-C isomer transformed enol-form into keto-form. In addition, the PEF treatments did not suffer the damage to VIT-C and could slow down the oxidation process in involving of experimental conditions by HPLC. The antioxidant properties of the treated VIT-C were enhanced, which was proved by radical scavenging and also the reducing power tests.

Effects of Pulsed Electric Fields (PEF) on Vitamin C and Its Antioxidant Properties

PubMed Central

Zhang, Zhi-Hong; Zeng, Xin-An; Brennan, Charles S.; Brennan, Margaret; Han, Zhong; Xiong, Xia-Yu

2015-01-01

In this study, pulsed electric fields (PEF) treatments and their effects on the structure of vitamin C (VIT-C) were estimated by fluorescence and Fourier transform infrared (FT-IR) spectroscopy, the relative content of VIT-C was measured by HPLC and the antioxidant properties of treated VIT-C by DPPH radical scavenging as well as reducing power tests. The fluorescence intensity of treated VIT-C increased slightly compared to the untreated VIT-C. Moreover, the effect of PEF on the structure of VIT-C was observed using the FT-IR spectra. These phenomena indicated that the PEF affected the conformation of VIT-C, which promoted the VIT-C isomer transformed enol-form into keto-form. In addition, the PEF treatments did not suffer the damage to VIT-C and could slow down the oxidation process in involving of experimental conditions by HPLC. The antioxidant properties of the treated VIT-C were enhanced, which was proved by radical scavenging and also the reducing power tests. PMID:26473846

Deformation of leaky-dielectric fluid globules under strong electric fields: Boundary layers and jets at large Reynolds numbers

NASA Astrophysics Data System (ADS)

Schnitzer, Ory; Frankel, Itzchak; Yariv, Ehud

2013-11-01

In Taylor's theory of electrohydrodynamic drop deformation (Proc. R. Soc. Lond. A, vol. 291, 1966, pp. 159-166), inertia is neglected at the outset, resulting in fluid velocity that scales as the square of the applied-field magnitude. For large drops, with increasing field strength the Reynolds number predicted by this scaling may actually become large, suggesting the need for a complementary large-Reynolds-number investigation. Balancing viscous stresses and electrical shear forces in this limit reveals a different velocity scaling, with the 4/3-power of the applied-field magnitude. We focus here on the flow over a gas bubble. It is essentially confined to two boundary layers propagating from the poles to the equator, where they collide to form a radial jet. At leading order in the Capillary number, the bubble deforms due to (i) Maxwell stresses; (ii) the hydrodynamic boundary-layer pressure associated with centripetal acceleration; and (iii) the intense pressure distribution acting over the narrow equatorial deflection zone, appearing as a concentrated load. Remarkably, the unique flow topology and associated scalings allow to obtain a closed-form expression for this deformation through application of integral mass and momentum balances. On the bubble scale, the concentrated pressure load is manifested in the appearance of a non-smooth equatorial dimple.

Oppositely charged colloids out of equilibrium

NASA Astrophysics Data System (ADS)

Vissers, T.

2010-11-01

Colloids are particles with a size in the range of a few nanometers up to several micrometers. Similar to atomic and molecular systems, they can form gases, liquids, solids, gels and glasses. Colloids can be used as model systems because, unlike molecules, they are sufficiently large to be studied directly with light microscopy and move sufficiently slow to study their dynamics. In this thesis, we study binary systems of polymethylmethacrylate (PMMA) colloidal particles suspended in low-polar solvent mixtures. Since the ions can still partially dissociate, a surface charge builds up which causes electrostatic interactions between the colloids. By carefully tuning the conditions inside the suspension, we make two kinds of particles oppositely charged. To study our samples, we use Confocal Laser Scanning Microscopy (CLSM). The positively and negatively charged particles can be distinguished by a different fluorescent dye. Colloids constantly experience a random motion resulting from random kicks of surrounding solvent molecules. When the attractions between the oppositely charged particles are weak, the particles can attach and detach many times and explore a lot of possible configurations and the system can reach thermodynamic equilibrium. For example, colloidal ‘ionic’ crystals consisting of thousands to millions of particles can form under the right conditions. When the attractions are strong, the system can become kinetically trapped inside a gel-like state. We observe that when the interactions change again, crystals can even emerge again from this gel-like phase. By using local order parameters, we quantitatively study the crystallization of colloidal particles and identify growth defects inside the crystals. We also study the effect of gravity on the growth of ionic crystals by using a rotating stage. We find that sedimentation can completely inhibit crystal growth and plays an important role in crystallization from the gel-like state. The surface potential and charge are studied by electrophoresis. Here, the velocity of the particles is measured while they are moving in an electric field. Using our real-space CLSM setup, we find that for a single-component system, the charge on the particles decreases with increasing volume fraction. Apart from structures that oppositely charged particles form close to thermodynamic equilibrium, we also study pattern formation when the system is driven out of equilibrium by an electric field. When oppositely charged particles are driven in opposite directions, the collisions between them cause particle of the same kind to form lanes. By combining our CLSM experiments with Brownian dynamics computer simulations, we study the structure and the dynamics of the suspension on the single-particle level. We find that the number of particles in a lane increases continuously with the field strength. By studying the dynamics and fluctuations parallel and perpendicular to the electric field direction, we identify the key mechanism of lane-formation. We show that pattern formation can easily become more complicated when we introduce alternating current (AC) fields. In addition to the formation of lanes parallel to the field-axis, bands of like-charged particles can form perpendicular to it. When the particles are sufficiently mobile, the system can be remixed again by changing the frequency. When AC-fields with higher field strengths are used, we show that complex patterns, including rotating instabilities, can emerge. The results in this thesis yield fundamental insight in electrophoresis, crystallization and pattern formation when systems are driven out of equilibrium. The results on lane- and band-formation can be relevant for the design of electronic ink (e-ink), where electrically driven oppositely charged particles are used to change the image on a piece of electronic paper.

Evaluation of the Atmospheric Boundary-Layer Electrical Variability

NASA Astrophysics Data System (ADS)

Anisimov, Sergey V.; Galichenko, Sergey V.; Aphinogenov, Konstantin V.; Prokhorchuk, Aleksandr A.

2017-12-01

Due to the chaotic motion of charged particles carried by turbulent eddies, electrical quantities in the atmospheric boundary layer (ABL) have short-term variability superimposed on long-term variability caused by sources from regional to global scales. In this study the influence of radon exhalation rate, aerosol distribution and turbulent transport efficiency on the variability of fair-weather atmospheric electricity is investigated via Lagrangian stochastic modelling. For the mid-latitude lower atmosphere undisturbed by precipitation, electrified clouds, or thunderstorms, the model is capable of reproducing the diurnal variation in atmospheric electrical parameters detected by ground-based measurements. Based on the analysis of field observations and numerical simulation it is found that the development of the convective boundary layer, accompanied by an increase in turbulent kinetic energy, forms the vertical distribution of radon and its decaying short-lived daughters to be approximately coincident with the barometric law for several eddy turnover times. In the daytime ABL the vertical distribution of atmospheric electrical conductivity tends to be uniform except within the surface layer, due to convective mixing of radon and its radioactive decay products. At the same time, a decrease in the conductivity near the ground is usually observed. This effect leads to an enhanced ground-level atmospheric electric field compared to that normally observed in the nocturnal stably-stratified boundary layer. The simulation showed that the variability of atmospheric electric field in the ABL associated with internal origins is significant in comparison to the variability related to changes in global parameters. It is suggested that vertical profiles of electrical quantities can serve as informative parameters on ABL turbulent dynamics and can even more broadly characterize the state of the environment.

Ferroelectric nanostructure having switchable multi-stable vortex states

DOEpatents

Naumov, Ivan I [Fayetteville, AR; Bellaiche, Laurent M [Fayetteville, AR; Prosandeev, Sergey A [Fayetteville, AR; Ponomareva, Inna V [Fayetteville, AR; Kornev, Igor A [Fayetteville, AR

2009-09-22

A ferroelectric nanostructure formed as a low dimensional nano-scale ferroelectric material having at least one vortex ring of polarization generating an ordered toroid moment switchable between multi-stable states. A stress-free ferroelectric nanodot under open-circuit-like electrical boundary conditions maintains such a vortex structure for their local dipoles when subject to a transverse inhomogeneous static electric field controlling the direction of the macroscopic toroidal moment. Stress is also capable of controlling the vortex's chirality, because of the electromechanical coupling that exists in ferroelectric nanodots.

Surface electrical properties experiment. Part 2: Theory of radio-frequency interferometry in geophysical subsurface probing

NASA Technical Reports Server (NTRS)

Kong, J. A.; Tsang, L.

1974-01-01

The radiation fields due to a horizontal electric dipole laid on the surface of a stratified medium were calculated using a geometrical optics approximation, a modal approach, and direct numerical integration. The solutions were obtained from the reflection coefficient formulation and written in integral forms. The calculated interference patterns are compared in terms of the usefulness of the methods used to obtain them. Scattering effects are also discussed and all numerical results for anisotropic and isotropic cases are presented.

High current ion source

DOEpatents

Brown, Ian G.; MacGill, Robert A.; Galvin, James E.

1990-01-01

An ion source utilizing a cathode and anode for producing an electric arc therebetween. The arc is sufficient to vaporize a portion of the cathode to form a plasma. The plasma leaves the generation region and expands through another regon. The density profile of the plasma may be flattened using a magnetic field formed within a vacuum chamber. Ions are extracted from the plasma to produce a high current broad on beam.

Electric-Field-Oriented Growth of Long Hair-Like Silica Microfibrils and Derived Functional Monolithic Solids

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

Hu, Michael Z.; DePaoli, David W.; Kuritz, Tanya

We present a “bottom-up” fabrication approach to first grow a new class of inorganic (silica) long hair-like microfibers or microwires and then to form monolithic solid pellet that contains parallel arrays of bundled microfibers with a controlled orientation. During the sol-gel solution processing, reactive precursor species are utilized as molecular “building blocks” for the field-directed assembly growth of microfibers driven by an electric field of pulsed direct current (dc) with controlled frequency. In principle, this reactive electrofibrilation process that combines an external field with a solid-phase nucleation and growth process has no limitation on reactions (such as the one heremore » that involves sol-gel reaction chemistry) and on materials compositions (such as the example silica oxide), thus will enable bulk production of long microfibers of wide variety of inorganic materials (other oxides or metals). Furthermore, we have fabricated uniquely architectured monolithic solid materials containing aligned microfibers by “wet press” of the in-situ grown microfiber structure in the electric field. The consolidated monolithic slabs (1 cm x 1 cm x 3 mm) have shown anisotropic properties and desirable retention of DNA molecule fragments, thus, could serve as a platform stationary-phase materials for future development of capillary electrochromatography for biomolecule separations.« less

Electric-Field-Oriented Growth of Long Hair-Like Silica Microfibrils and Derived Functional Monolithic Solids

DOE PAGES

Hu, Michael Z.; DePaoli, David W.; Kuritz, Tanya; ...

2017-09-11

We present a “bottom-up” fabrication approach to first grow a new class of inorganic (silica) long hair-like microfibers or microwires and then to form monolithic solid pellet that contains parallel arrays of bundled microfibers with a controlled orientation. During the sol-gel solution processing, reactive precursor species are utilized as molecular “building blocks” for the field-directed assembly growth of microfibers driven by an electric field of pulsed direct current (dc) with controlled frequency. In principle, this reactive electrofibrilation process that combines an external field with a solid-phase nucleation and growth process has no limitation on reactions (such as the one heremore » that involves sol-gel reaction chemistry) and on materials compositions (such as the example silica oxide), thus will enable bulk production of long microfibers of wide variety of inorganic materials (other oxides or metals). Furthermore, we have fabricated uniquely architectured monolithic solid materials containing aligned microfibers by “wet press” of the in-situ grown microfiber structure in the electric field. The consolidated monolithic slabs (1 cm x 1 cm x 3 mm) have shown anisotropic properties and desirable retention of DNA molecule fragments, thus, could serve as a platform stationary-phase materials for future development of capillary electrochromatography for biomolecule separations.« less

Three-dimensional imaging of vortex structure in a ferroelectric nanoparticle driven by an electric field.

PubMed

Karpov, D; Liu, Z; Rolo, T Dos Santos; Harder, R; Balachandran, P V; Xue, D; Lookman, T; Fohtung, E

2017-08-17

Topological defects of spontaneous polarization are extensively studied as templates for unique physical phenomena and in the design of reconfigurable electronic devices. Experimental investigations of the complex topologies of polarization have been limited to surface phenomena, which has restricted the probing of the dynamic volumetric domain morphology in operando. Here, we utilize Bragg coherent diffractive imaging of a single BaTiO 3 nanoparticle in a composite polymer/ferroelectric capacitor to study the behavior of a three-dimensional vortex formed due to competing interactions involving ferroelectric domains. Our investigation of the structural phase transitions under the influence of an external electric field shows a mobile vortex core exhibiting a reversible hysteretic transformation path. We also study the toroidal moment of the vortex under the action of the field. Our results open avenues for the study of the structure and evolution of polar vortices and other topological structures in operando in functional materials under cross field configurations.Imaging of topological states of matter such as vortex configurations has generally been limited to 2D surface effects. Here Karpov et al. study the volumetric structure and dynamics of a vortex core mediated by electric-field induced structural phase transition in a ferroelectric BaTiO 3 nanoparticle.

Complex Pattern Formation from Current-Driven Dynamics of Single-Layer Epitaxial Islands on Crystalline Conducting Substrates

NASA Astrophysics Data System (ADS)

Kumar, Ashish; Dasgupta, Dwaipayan; Maroudas, Dimitrios

We report a systematic study of complex pattern formation resulting from the driven dynamics of single-layer homoepitaxial islands on face-centered cubic (FCC) crystalline conducting substrate surfaces under the action of an externally applied electric field. The analysis is based on an experimentally validated nonlinear model of mass transport via island edge atomic diffusion, which also accounts for edge diffusional anisotropy. We analyze the morphological stability and simulate the field-driven evolution of rounded islands for an electric field oriented along the fast diffusion direction. For larger than critical island sizes on {110} and {100} FCC substrates, we show that multiple necking instabilities generate complex island patterns, including void-containing islands, mediated by sequences of breakup and coalescence events and distributed symmetrically with respect to the electric field direction. We analyze the dependence of the formed patterns on the original island size and on the duration of application of the external field. Starting from a single large rounded island, we characterize the evolution of the number of daughter islands and their average size and uniformity. The analysis reveals that the pattern formation kinetics follows a universal scaling relation. Division of Materials Sciences & Engineering, Office of Basic Energy Sciences, U.S. Department of Energy (Award No.: DE-FG02-07ER46407).

Effects of electric fields on the photonic crystal formation from block copolymers

NASA Astrophysics Data System (ADS)

Lee, Taekun; Ju, Jin-wook; Ryoo, Won

2012-03-01

Effects of electric fields on the self-assembly of block copolymers have been investigated for thin films of polystyrene-bpoly( 2-vinyl pyridine); PS-b-P2VP, 52 kg/mol-b-57 kg/mol and 133 kg/mol-b-132 kg/mol. Block copolymers of polystyrene and poly(2-vinyl pyridine) have been demonstrated to form photonic crystals of 1D lamellar structure with optical band gaps that correspond to UV-to-visible light. The formation of lamellar structure toward minimum freeenergy state needs increasing polymer chain mobility, and the self-assembly process is accelerated usually by annealing, that is exposing the thin film to solvent vapor such as chloroform and dichloromethane. In this study, thin films of block copolymers were spin-coated on substrates and placed between electrode arrays of various patterns including pin-points, crossing and parallel lines. As direct or alternating currents were applied to electrode arrays during annealing process, the final structure of thin films was altered from the typical 1D lamellae in the absence of electric fields. The formation of lamellar structure was spatially controlled depending on the shape of electrode arrays, and the photonic band gap also could be modulated by electric field strength. The spatial formation of lamellar structure was examined with simulated distribution of electrical potentials by finite difference method (FDM). P2VP layers in self-assembled film were quaternized with methyl iodide vapor, and the remaining lamellar structure was investigated by field emission scanning electron microscope (FESEM). The result of this work is expected to provide ways of fabricating functional structures for display devices utilizing photonic crystal array.

A theoretical study on the electronic structure of Au-XO(0,-1,+1) (X=C, N, and O) complexes: effect of an external electric field.

PubMed

Tielens, Frederik; Gracia, Lourdes; Polo, Victor; Andrés, Juan

2007-12-20

A theoretical study on the nature of Au-XO(0,-1,+1) (X=C, N, O) interaction is carried out in order to provide a better understanding on the adsorption process of XO molecules on Au surfaces or Au-supported surfaces. The effect of the total charge as well as the presence of an external electric field on the formation processes of the Au-XO complex are analyzed and discussed using DFT (B3LYP) and high-level ab initio (CCSD(T)//MP2) methods employing a 6-311+G(3df) basis set for X and O atoms and Stuttgart pseudopotentials for Au atom. The presence of an electric field can increase the binding of O2 molecule to Au while weakening the formation of the Au-CO complex. These behaviors are discussed in the context of adsorption or deadsorption of these molecules on Au clusters. The formation of the Au-XO complex, the effect of addition/removal of one electron, and the role of the electric field are rationalized by studying the nature of the bonding interactions by means of the electron localization function (ELF) analysis. The net interaction between Au and XO fragments is governed by the interplay of three factors: (i) the amount of charge transfer from Au to XO, (ii) the sharing of the lone pair from X atom by the Au core (V(X, Au) basin), and (iii) the role of the lone pair of Au (V(Au) basin) mainly formed by 6s electrons. The total charge of the system and the applied electric field determine the population and orientation of the V(Au) basin and, subsequently, the degree of repulsion with the V(X, Au) basin.

Method of fabricating free-form, high-aspect ratio components for high-current, high-speed microelectrics

DOEpatents

Maxwell, James L; Rose, Chris R; Black, Marcie R; Springer, Robert W

2014-03-11

Microelectronic structures and devices, and method of fabricating a three-dimensional microelectronic structure is provided, comprising passing a first precursor material for a selected three-dimensional microelectronic structure into a reaction chamber at temperatures sufficient to maintain said precursor material in a predominantly gaseous state; maintaining said reaction chamber under sufficient pressures to enhance formation of a first portion of said three-dimensional microelectronic structure; applying an electric field between an electrode and said microelectronic structure at a desired point under conditions whereat said first portion of a selected three-dimensional microelectronic structure is formed from said first precursor material; positionally adjusting either said formed three-dimensional microelectronic structure or said electrode whereby further controlled growth of said three-dimensional microelectronic structure occurs; passing a second precursor material for a selected three-dimensional microelectronic structure into a reaction chamber at temperatures sufficient to maintain said precursor material in a predominantly gaseous state; maintaining said reaction chamber under sufficient pressures whereby a second portion of said three-dimensional microelectronic structure formation is enhanced; applying an electric field between an electrode and said microelectronic structure at a desired point under conditions whereat said second portion of a selected three-dimensional microelectronic structure is formed from said second precursor material; and, positionally adjusting either said formed three-dimensional microelectronic structure or said electrode whereby further controlled growth of said three-dimensional microelectronic structure occurs.

Single channel double-duct liquid metal electrical generator using a magnetohydrodynamic device

DOEpatents

Haaland, C.M.; Deeds, W.E.

1999-07-13

A single channel double-duct liquid metal electrical generator using a magnetohydrodynamic (MHD) device. The single channel device provides useful output AC electric energy. The generator includes a two-cylinder linear-piston engine which drives liquid metal in a single channel looped around one side of the MHD device to form a double-duct contra-flowing liquid metal MHD generator. A flow conduit network and drive mechanism are provided for moving liquid metal with an oscillating flow through a static magnetic field to produce useful AC electric energy at practical voltages and currents. Variable stroke is obtained by controlling the quantity of liquid metal in the channel. High efficiency is obtained over a wide range of frequency and power output. 5 figs.

Single channel double-duct liquid metal electrical generator using a magnetohydrodynamic device

DOEpatents

Haaland, Carsten M.; Deeds, W. Edward

1999-01-01

A single channel double-duct liquid metal electrical generator using a magnetohydrodynamic (MHD) device. The single channel device provides useful output AC electric energy. The generator includes a two-cylinder linear-piston engine which drives liquid metal in a single channel looped around one side of the MHD device to form a double-duct contra-flowing liquid metal MHD generator. A flow conduit network and drive mechanism are provided for moving liquid metal with an oscillating flow through a static magnetic field to produce useful AC electric energy at practical voltages and currents. Variable stroke is obtained by controlling the quantity of liquid metal in the channel. High efficiency is obtained over a wide range of frequency and power output.

Electrical Transport Properties of Liquid Al-Cu Alloys

NASA Astrophysics Data System (ADS)

Thakore, B. Y.; Khambholja, S. G.; Suthar, P. H.; Jani, A. R.

2010-06-01

Electrical transport properties viz. electrical resistivity, thermoelectric power and thermal conductivity of liquid Al-Cu alloys as a function of Cu concentration have been studied in the present paper. Ashcroft empty core model potential has been used to incorporate the ion-electron interaction. To incorporate the exchange and correlation effects, five different forms of local field correction functions viz. Hartree, Taylor, Ichimaru et al., Farid et al. and Sarkar et al. have been used. The transport properties of binary system have been studied using Faber-Ziman formulation combined with Ashcroft-Langreth (AL) partial structure factor. The computed values of electrical resistivity are compared with experimental data and for low Cu concentration, good agreement has been observed. Further, thermoelectric power and thermal conductivity have also been predicted.

Studies into Equine Electrocardiography and Vectorcardiography

PubMed Central

Holmes, J. R.; Alps, B. J.

1967-01-01

Theoretical consideration has been given in two horses to the properties of the electric field created by the equine heart acting as a simple electric generator. The principles of the vectorial theory have been applied to test the validity of application of the dipole concept. The cardiac electric forces, althrough complex in the immediate region of the heart, appear at the body surface in a similar form to those arising from a relatively immobile, single equivalent dipole. The potential value of the technique of vectorcardiography in cardiological investigations is briefly discussed. ImagesFig. 1.Fig. 3.Fig. 5.Fig. 10.Fig. 12.Fig. 13. PMID:17649586

Observation of the avalanche of runaway electrons in air in a strong electric field.

PubMed

Gurevich, A V; Mesyats, G A; Zybin, K P; Yalandin, M I; Reutova, A G; Shpak, V G; Shunailov, S A

2012-08-24

The generation of an avalanche of runaway electrons is demonstrated for the first time in a laboratory experiment. Two flows of runaway electrons are formed sequentially in an extended air discharge gap at the stage of delay of a pulsed breakdown. The first, picosecond, runaway electron flow is emitted in the cathode region where the field is enhanced. Being accelerated in the gap, this beam generates electrons due to impact ionization. These secondary electrons form a delayed avalanche of runaway electrons if the field is strong enough. The properties of the avalanche correspond to the existing notions about the runaway breakdown in air. The measured current of the avalanche exceeds up to an order the current of the initiating electron beam.

Observation of the Avalanche of Runaway Electrons in Air in a Strong Electric Field

NASA Astrophysics Data System (ADS)

Gurevich, A. V.; Mesyats, G. A.; Zybin, K. P.; Yalandin, M. I.; Reutova, A. G.; Shpak, V. G.; Shunailov, S. A.

2012-08-01

The generation of an avalanche of runaway electrons is demonstrated for the first time in a laboratory experiment. Two flows of runaway electrons are formed sequentially in an extended air discharge gap at the stage of delay of a pulsed breakdown. The first, picosecond, runaway electron flow is emitted in the cathode region where the field is enhanced. Being accelerated in the gap, this beam generates electrons due to impact ionization. These secondary electrons form a delayed avalanche of runaway electrons if the field is strong enough. The properties of the avalanche correspond to the existing notions about the runaway breakdown in air. The measured current of the avalanche exceeds up to an order the current of the initiating electron beam.

The "Forgotten" Pseudomomenta and Gauge Changes in Generalized Landau Level Problems: Spatially Nonuniform Magnetic and Temporally Varying Electric Fields

NASA Astrophysics Data System (ADS)

Konstantinou, Georgios; Moulopoulos, Konstantinos

2017-05-01

By perceiving gauge invariance as an analytical tool in order to get insight into the states of the "generalized Landau problem" (a charged quantum particle moving inside a magnetic, and possibly electric field), and motivated by an early article that correctly warns against a naive use of gauge transformation procedures in the usual Landau problem (i.e. with the magnetic field being static and uniform), we first show how to bypass the complications pointed out in that article by solving the problem in full generality through gauge transformation techniques in a more appropriate manner. Our solution provides in simple and closed analytical forms all Landau Level-wavefunctions without the need to specify a particular vector potential. This we do by proper handling of the so-called pseudomomentum ěc {{K}} (or of a quantity that we term pseudo-angular momentum L z ), a method that is crucially different from the old warning argument, but also from standard treatments in textbooks and in research literature (where the usual Landau-wavefunctions are employed - labeled with canonical momenta quantum numbers). Most importantly, we go further by showing that a similar procedure can be followed in the more difficult case of spatially-nonuniform magnetic fields: in such case we define ěc {{K}} and L z as plausible generalizations of the previous ordinary case, namely as appropriate line integrals of the inhomogeneous magnetic field - our method providing closed analytical expressions for all stationary state wavefunctions in an easy manner and in a broad set of geometries and gauges. It can thus be viewed as complementary to the few existing works on inhomogeneous magnetic fields, that have so far mostly focused on determining the energy eigenvalues rather than the corresponding eigenkets (on which they have claimed that, even in the simplest cases, it is not possible to obtain in closed form the associated wavefunctions). The analytical forms derived here for these wavefunctions enable us to also provide explicit Berry's phase calculations and a quick study of their connection to probability currents and to some recent interesting issues in elementary Quantum Mechanics and Condensed Matter Physics. As an added feature, we also show how the possible presence of an additional electric field can be treated through a further generalization of pseudomomenta and their proper handling.

The correlated molecular electrostatic potential and electric field of 2 (1H)-pyrimidone and 2-hydroxypyrimidine

NASA Astrophysics Data System (ADS)

Leś, Andrzej; Adamowicz, Ludwik

1991-06-01

The molecular electrostatic potential and molecular electric field have been estimated by means of the expectation values of the respective one-electron operators. We used the molecular density matrix that includes the electron correlation effects up to the second-order of the many body perturbation theory. The results show that around the 2(1H)-pyrimidone molecule one may distinguish the electrophilic and nucleophilic regions, the latter characterized by two potential minima of -2.9 V. In the tautomeric form, 2-hydroxypyrimidine, a third potential minimum of -2.1 V appears close to the N1 nitrogen atom. For both molecules strong orientational forces acting on polar solvents are predicted in the vicinity of oxygen (O7) and nitrogen (N3) atoms. The electron correlation effects do not significantly alter the SCF values of the electrostatic potential and electric field at the distances within the van der Waals envelope of the pyrimidine bases. At larger distances, however, the correlation correction is significant, particularly in the direction facing the proton transfer path.

Dusty Plasma Dynamics Near Surfaces in Space

NASA Technical Reports Server (NTRS)

Colwell, Joshua E.; Robertson, S.; Horanyi, M.; Nahra, Henry (Technical Monitor)

1998-01-01

The investigation 'Dusty Plasma Dynamics Near Surfaces in Space' is an experimental and theoretical study of the dynamics of dust particles on airless bodies in the solar system in the presence of a photoelectron sheath generated by solar ultraviolet light impinging on the surface. Solar UV illumination of natural and manmade surfaces in space produces photoelectrons which form a plasma sheath near the surface. Dust particles on the surface acquire a charge and may be transported by electric fields in the photoelectron sheath generated by inhomogeneities in the surface or the illumination (such as shadows). The sheath itself has a finite vertical extent leading to (at least) an electric field normal to the illuminated surface. If dust particles are launched from the surface by some other process, such as meteoroid impact, or spacecraft activity on the surface, these grains become charged and move under the influence of gravity and the electric field. This can give rise to suspension of the particles above the surface, loss from the parent body entirely (if accelerated beyond escape velocity), and a different distribution of dust ejecta from what would be expected with purely gravitational dynamics.

An in-depth description of bipolar resistive switching in Cu/HfOx/Pt devices, a 3D kinetic Monte Carlo simulation approach

NASA Astrophysics Data System (ADS)

Aldana, S.; Roldán, J. B.; García-Fernández, P.; Suñe, J.; Romero-Zaliz, R.; Jiménez-Molinos, F.; Long, S.; Gómez-Campos, F.; Liu, M.

2018-04-01

A simulation tool based on a 3D kinetic Monte Carlo algorithm has been employed to analyse bipolar conductive bridge RAMs fabricated with Cu/HfOx/Pt stacks. Resistive switching mechanisms are described accounting for the electric field and temperature distributions within the dielectric. The formation and destruction of conductive filaments (CFs) are analysed taking into consideration redox reactions and the joint action of metal ion thermal diffusion and electric field induced drift. Filamentary conduction is considered when different percolation paths are formed in addition to other conventional transport mechanisms in dielectrics. The simulator was tuned by using the experimental data for Cu/HfOx/Pt bipolar devices that were fabricated. Our simulation tool allows for the study of different experimental results, in particular, the current variations due to the electric field changes between the filament tip and the electrode in the High Resistance State. In addition, the density of metallic atoms within the CF can also be characterized along with the corresponding CF resistance description.

Effect of Electric Field on Gas Hydrate Nucleation Kinetics: Evidence for the Enhanced Kinetics of Hydrate Nucleation by Negatively Charged Clay Surfaces.

PubMed

Park, Taehyung; Kwon, Tae-Hyuk

2018-03-06

Natural gas hydrates are found widely in oceanic clay-rich sediments, where clay-water interactions have a profound effect on the formation behavior of gas hydrates. However, it remains unclear why and how natural gas hydrates are formed in clay-rich sediments in spite of factors that limit gas hydrate formation, such as small pore size and high salinity. Herein, we show that polarized water molecules on clay surfaces clearly promote gas hydrate nucleation kinetics. When water molecules were polarized with an electric field of 10 4 V/m, gas hydrate nucleation occurred significantly faster with an induction time reduced by 5.8 times. Further, the presence of strongly polarized water layers at the water-gas interface hindered gas uptake and thus hydrate formation, when the electric field was applied prior to gas dissolution. Our findings expand our understanding of the formation habits of naturally occurring gas hydrates in clay-rich sedimentary deposits and provide insights into gas production from natural hydrate deposits.

Superconductivity in diamond.

PubMed

Ekimov, E A; Sidorov, V A; Bauer, E D; Mel'nik, N N; Curro, N J; Thompson, J D; Stishov, S M

2004-04-01

Diamond is an electrical insulator well known for its exceptional hardness. It also conducts heat even more effectively than copper, and can withstand very high electric fields. With these physical properties, diamond is attractive for electronic applications, particularly when charge carriers are introduced (by chemical doping) into the system. Boron has one less electron than carbon and, because of its small atomic radius, boron is relatively easily incorporated into diamond; as boron acts as a charge acceptor, the resulting diamond is effectively hole-doped. Here we report the discovery of superconductivity in boron-doped diamond synthesized at high pressure (nearly 100,000 atmospheres) and temperature (2,500-2,800 K). Electrical resistivity, magnetic susceptibility, specific heat and field-dependent resistance measurements show that boron-doped diamond is a bulk, type-II superconductor below the superconducting transition temperature T(c) approximately 4 K; superconductivity survives in a magnetic field up to Hc2(0) > or = 3.5 T. The discovery of superconductivity in diamond-structured carbon suggests that Si and Ge, which also form in the diamond structure, may similarly exhibit superconductivity under the appropriate conditions.

Electrical Deflection of Polar Liquid Streams: A Misunderstood Demonstration

NASA Astrophysics Data System (ADS)

Ziaei-Moayyed, Maryam; Goodman, Edward; Williams, Peter

2000-11-01

The electrical deflection of polar liquid streams, commonly used as a textbook illustration of the behavior of polar molecules, is shown to be due to the formation of electrically charged droplets in the polar liquid stream, induced by a nearby charged object, rather than any force exerted on molecular dipoles. Streams of water and polar organic liquids could be deflected in a uniform electric field, which could not have exerted any force on dipolar species. Water and polar organic liquid streams formed within a grounded, electrically screened region could not be deflected after exiting the screened region, demonstrating that there is no electrical force on uncharged polar liquid droplets. Induced charging was observed also in insulating polar organic liquids and is suggested to be due to ionic impurities. A weak deflection of a stream of a nonpolar liquid (tetrachloroethylene) was also observed, indicating that such impurity effects are quite general, even in nonpolar liquids.

Fluidic Active Transducer for Electricity Generation

PubMed Central

Yang, YoungJun; Park, Junwoo; Kwon, Soon-Hyung; Kim, Youn Sang

2015-01-01

Flows in small size channels have been studied for a long time over multidisciplinary field such as chemistry, biology and medical through the various topics. Recently, the attempts of electricity generation from the small flows as a new area for energy harvesting in microfluidics have been reported. Here, we propose for the first time a new fluidic electricity generator (FEG) by modulating the electric double layer (EDL) with two phase flows of water and air without external power sources. We find that an electric current flowed by the forming/deforming of the EDL with a simple separated phase flow of water and air at the surface of the FEG. Electric signals between two electrodes of the FEG are checked from various water/air passing conditions. Moreover, we verify the possibility of a self-powered air slug sensor by applying the FEG in the detection of an air slug. PMID:26511626

Apparatuses and methods for generating electric fields

DOEpatents

Scott, Jill R; McJunkin, Timothy R; Tremblay, Paul L

2013-08-06

Apparatuses and methods relating to generating an electric field are disclosed. An electric field generator may include a semiconductive material configured in a physical shape substantially different from a shape of an electric field to be generated thereby. The electric field is generated when a voltage drop exists across the semiconductive material. A method for generating an electric field may include applying a voltage to a shaped semiconductive material to generate a complex, substantially nonlinear electric field. The shape of the complex, substantially nonlinear electric field may be configured for directing charged particles to a desired location. Other apparatuses and methods are disclosed.

Application of the Landau-Zener-Stückelberg-Majorana dynamics to the electrically driven flip of a hole spin

NASA Astrophysics Data System (ADS)

Pasek, W. J.; Maialle, M. Z.; Degani, M. H.

2018-03-01

An idea of employing the Landau-Zener-Stückelberg-Majorana dynamics to flip a spin of a single ground state hole is introduced and explored by a time-dependent simulation. This configuration interaction study considers a hole confined in a quantum molecule formed in an InSb 〈111 〉 quantum wire by application of an electrostatic potential. An up-down spin-mixing avoided crossing is formed by nonaxial terms in the Kohn-Luttinger Hamiltonian and the Dresselhaus spin-orbit one. Manipulation of the system is possible by the dynamic change of an external vertical electric field, which enables the consecutive driving of the hole through two anticrossings. Moreover, a simple model of the power-law-type noise that impedes precise electric control of the system is included in the form of random telegraph noise to estimate the limitations of the working conditions. We show that in principle the process is possible, but it requires precise control of the parameters of the driving impulse.

The IEEE Software Engineering Standards Process

PubMed Central

Buckley, Fletcher J.

1984-01-01

Software Engineering has emerged as a field in recent years, and those involved increasingly recognize the need for standards. As a result, members of the Institute of Electrical and Electronics Engineers (IEEE) formed a subcommittee to develop these standards. This paper discusses the ongoing standards development, and associated efforts.

Introduction to power-frequency electric and magnetic fields.

PubMed Central

Kaune, W T

1993-01-01

This paper introduces the reader to electric and magnetic fields, particularly those fields produced by electric power systems and other sources using frequencies in the power-frequency range. Electric fields are produced by electric charges; a magnetic field also is produced if these charges are in motion. Electric fields exert forces on other charges; if in motion, these charges will experience magnetic forces. Power-frequency electric and magnetic fields induce electric currents in conducting bodies such as living organisms. The current density vector is used to describe the distribution of current within a body. The surface of the human body is an excellent shield for power-frequency electric fields, but power-frequency magnetic fields penetrate without significant attenuation; the electric fields induced inside the body by either exposure are comparable in magnitude. Electric fields induced inside a human by most environmental electric and magnetic fields appear to be small in magnitude compared to levels naturally occurring in living tissues. Detection of such fields thus would seem to require the existence of unknown biological mechanisms. Complete characterization of a power-frequency field requires measurement of the magnitudes and electrical phases of the fundamental and harmonic amplitudes of its three vector components. Most available instrumentation measures only a small subset, or some weighted average, of these quantities. Hand-held survey meters have been used widely to measure power-frequency electric and magnetic fields. Automated data-acquisition systems have come into use more recently to make electric- and magnetic-field recordings, covering periods of hours to days, in residences and other environments.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8206045

Numerical modelling of processes that occur in the selective waste disassembly installation

NASA Astrophysics Data System (ADS)

Cherecheş, T.; Lixandru, P.; Dragnea, D.; Cherecheş, D. M.

2017-08-01

This paper is the result of the attempts of quantitative approach of some of the processes that are occurring in the selective fragmentation with high voltage pulses installation. It has been formulated a methodology which customizes the general methods for the issue of transient electric field in mixed environments. The electromagnetic processes inside the fragmentation installation, the initiation and formation of the discharge channels, the thermodynamic and mechanical effects in the process vessel are complex, transient and very quick. One of the underlying principles of the fragmentation process consists in the differentiated reaction of materials in an electric field. Generally in the process vessel there can be found together three types of materials: dielectrics, metal, electrolytes. The conductivity of dielectric materials is virtually zero. Metallic materials conduct very well through electronic conductivity. Electrolytes have a more modest conductivity since they conduct through electrochemical processes. The electrical current, in this case, is the movement of ions having sizes and the masses different from the electrons. Here, the electric current includes displacements of ions and molecules, collisions and chemical reactions. Part of the electrical field’s energy is absorbed by the electrolyte in the form of mechanical and chemical energy.

Eshelby problem of polygonal inclusions in anisotropic piezoelectric full- and half-planes

NASA Astrophysics Data System (ADS)

Pan, E.

2004-03-01

This paper presents an exact closed-form solution for the Eshelby problem of polygonal inclusion in anisotropic piezoelectric full- and half-planes. Based on the equivalent body-force concept of eigenstrain, the induced elastic and piezoelectric fields are first expressed in terms of line integral on the boundary of the inclusion with the integrand being the Green's function. Using the recently derived exact closed-form line-source Green's function, the line integral is then carried out analytically, with the final expression involving only elementary functions. The exact closed-form solution is applied to a square-shaped quantum wire within semiconductor GaAs full- and half-planes, with results clearly showing the importance of material orientation and piezoelectric coupling. While the elastic and piezoelectric fields within the square-shaped quantum wire could serve as benchmarks to other numerical methods, the exact closed-form solution should be useful to the analysis of nanoscale quantum-wire structures where large strain and electric fields could be induced by the misfit strain.

The Origin and Coupling Mechanism of the Magnetoelectric Effect in TM Cl 2 -4SC(NH 2 ) 2 ( TM = Ni and Co)

DOE PAGES

Mun, Eundeok; Wilcox, Jason; Manson, Jamie L.; ...

2014-01-01

Most research on multiferroics and magnetoelectric effects to date has focused on inorganic oxides. Molecule-based materials are a relatively new field in which to search for magnetoelectric multiferroics and to explore new coupling mechanisms between electric and magnetic order. We present magnetoelectric behavior in NiCl 2 -4SC(NH 2 ) 2 (DTN) and CoCl 2 -4SC(NH 2 ) 2 (DTC). These compounds form tetragonal structures where the transition metal ion (Ni or Co) is surrounded by four electrically polar thiourea molecules [SC(NH 2 ) 2 ]. By tracking the magnetic and electric properties of these compounds as a function of magneticmore » field, we gain insights into the coupling mechanism by observing that, in DTN, the electric polarization tracks the magnetic ordering, whereas in DTC it does not. For DTN, all electrically polar thiourea molecules tilt in the same direction along the c -axis, breaking spatial-inversion symmetry, whereas, for DTC, two thiourea molecules tilt up and two tilt down with respect to c -axis, perfectly canceling the net electrical polarization. Thus, the magnetoelectric coupling mechanism in DTN is likely a magnetostrictive adjustment of the thiourea molecule orientation in response to magnetic order.« less

Preparation of monodisperse microbubbles using an integrated embedded capillary T-junction with electrohydrodynamic focusing.

PubMed

Parhizkar, Maryam; Stride, Eleanor; Edirisinghe, Mohan

2014-07-21

This work investigates the generation of monodisperse microbubbles using a microfluidic setup combined with electrohydrodynamic processing. A basic T-junction microfluidic device was modified by applying an electrical potential difference across the outlet channel. A model glycerol air system was selected for the experiments. In order to investigate the influence of the electric field strength on bubble formation, the applied voltage was increased systematically up to 21 kV. The effect of solution viscosity and electrical conductivity was also investigated. It was found that with increasing electrical potential difference, the size of the microbubbles reduced to ~25% of the capillary diameter whilst their size distribution remained narrow (polydispersity index ~1%). A critical value of 12 kV was found above which no further significant reduction in the size of the microbubbles was observed. The findings suggest that the size of the bubbles formed in the T-junction (i.e. in the absence of the electric field) is strongly influenced by the viscosity of the solution. The eventual size of bubbles produced by the composite device, however, was only weakly dependent upon viscosity. Further experiments, in which the solution electrical conductivity was varied by the addition of a salt indicated that this had a much stronger influence upon bubble size.

Particle Segregation in a Flowing Suspension Subject to High-Gradient Strong Electric Fields

NASA Technical Reports Server (NTRS)

Acrivos, Andreas; Qiu, Zhiyong; Khusid, Boris; Markarian, Nikolai

2002-01-01

The widespread use of electro-hydrodynamic devices and processes emphasizes a critical need for developing a comprehensive predictive theory capable of improving our fundamental understanding of the behavior of a suspension subject to an AC electric field and shear, and of facilitating the design and optimization of such devices. The currently favored approach to the qualitative interpretation of the AC field driven manipulation of suspensions is based on a model which considers only the force exerted on a single particle by an external field and neglects the field-induced and hydrodynamic interparticle interactions both being inversely proportional to the interparticle distance raised to the power three. On the other hand, the purpose of the field-induced separation is to concentrate particles in certain regions of a device. This clearly raises the fundamental question regarding the extent to which we can neglect these slow decaying electrical and hydrodynamic collective interactions and rely on the predictions of a single-particle model. Another important issue that still remains open is how to characterize the polarization of a particle exposed to a strong electric field. The presentation will address both these questions. Experiments were conducted in a parallel-plate channel in which a 10(exp -3) (v/v) suspension of heavy, positively polarized Al2O3 spheres was exposed to an AC field under conditions such that the field lines were arranged in the channel cross-section perpendicular to the streamlines of the main flow. To reduce the effects of the gravitational settling of the particles, the channel was slowly rotated (4 rpm) around a horizontal axis. Following the application of a high-gradient strong AC field (approx. kV/mm), the particles were found to move towards both the high-voltage (HV) and grounded (GR) electrodes and to form 'bristles' along their edges.

Micromachined electrical cauterizer

DOEpatents

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

1999-01-01

A micromachined electrical cauterizer. Microstructures are combined with microelectrodes for highly localized electro cauterization. Using boron etch stops and surface micromachining, microneedles with very smooth surfaces are made. Micromachining also allows for precision placement of electrodes by photolithography with micron sized gaps to allow for concentrated electric fields. A microcauterizer is fabricated by bulk etching silicon to form knife edges, then parallelly placed microelectrodes with gaps as small as 5 .mu.m are patterned and aligned adjacent the knife edges to provide homeostasis while cutting tissue. While most of the microelectrode lines are electrically insulated from the atmosphere by depositing and patterning silicon dioxide on the electric feedthrough portions, a window is opened in the silicon dioxide to expose the parallel microelectrode portion. This helps reduce power loss and assist in focusing the power locally for more efficient and safer procedures.

Micromachined electrical cauterizer

DOEpatents

Lee, A.P.; Krulevitch, P.A.; Northrup, M.A.

1999-08-31

A micromachined electrical cauterizer is disclosed. Microstructures are combined with microelectrodes for highly localized electro cauterization. Using boron etch stops and surface micromachining, microneedles with very smooth surfaces are made. Micromachining also allows for precision placement of electrodes by photolithography with micron sized gaps to allow for concentrated electric fields. A microcauterizer is fabricated by bulk etching silicon to form knife edges, then parallelly placed microelectrodes with gaps as small as 5 {mu}m are patterned and aligned adjacent the knife edges to provide homeostasis while cutting tissue. While most of the microelectrode lines are electrically insulated from the atmosphere by depositing and patterning silicon dioxide on the electric feedthrough portions, a window is opened in the silicon dioxide to expose the parallel microelectrode portion. This helps reduce power loss and assist in focusing the power locally for more efficient and safer procedures. 7 figs.

Atmosphere-Ionosphere Electrodynamic Coupling

NASA Astrophysics Data System (ADS)

Sorokin, V. M.; Chmyrev, V. M.

Numerous phenomena that occur in the mesosphere, ionosphere, and the magnetosphere of the Earth are caused by the sources located in the lower atmosphere and on the ground. We describe the effects produced by lightning activity and by ground-based transmitters operated in high frequency (HF) and very low frequency (VLF) ranges. Among these phenomena are the ionosphere heating and the formation of plasma density inhomogeneities, the excitation of gamma ray bursts and atmospheric emissions in different spectral bands, the generation of ULF/ELF/VLF electromagnetic waves and plasma turbulence in the ionosphere, the stimulation of radiation belt electron precipitations and the acceleration of ions in the upper ionosphere. The most interesting results of experimental and theoretical studies of these phenomena are discussed below. The ionosphere is subject to the action of the conductive electric current flowing in the atmosphere-ionosphere circuit. We present a physical model of DC electric field and current formation in this circuit. The key element of this model is an external current, which is formed with the occurrence of convective upward transport of charged aerosols and their gravitational sedimentation in the atmosphere. An increase in the level of atmospheric radioactivity results in the appearance of additional ionization and change of electrical conductivity. Variation of conductivity and external current in the lower atmosphere leads to perturbation of the electric current flowing in the global atmosphere-ionosphere circuit and to the associated DC electric field perturbation both on the Earth's surface and in the ionosphere. Description of these processes and some results of the electric field and current calculations are presented below. The seismic-induced electric field perturbations produce noticeable effects in the ionosphere by generating the electromagnetic field and plasma disturbances. We describe the generation mechanisms of such experimentally observed effects as excitation of plasma density inhomogeneities, field-aligned currents, and ULF/ELF emissions and the modification of electron and ion altitude profiles in the upper ionosphere. The electrodynamic model of the ionosphere modification under the influence of some natural and man-made processes in the atmosphere is also discussed. The model is based on the satellite and ground measurements of electromagnetic field and plasma perturbations and on the data on atmospheric radioactivity and soil gas injection into the atmosphere.

Method of bonding single crystal quartz by field-assisted bonding

DOEpatents

Curlee, R.M.; Tuthill, C.D.; Watkins, R.D.

1991-04-23

The method of producing a hermetic stable structural bond between quartz crystals includes providing first and second quartz crystals and depositing thin films of borosilicate glass and silicon on portions of the first and second crystals, respectively. The portions of the first and second crystals are then juxtaposed in a surface contact relationship and heated to a temperature for a period sufficient to cause the glass and silicon films to become electrically conductive. An electrical potential is then applied across the first and second crystals for creating an electrostatic field between the adjoining surfaces and causing the juxtaposed portions to be attracted into an intimate contact and form a bond for joining the adjoining surfaces of the crystals. 2 figures.

Method of bonding single crystal quartz by field-assisted bonding

DOEpatents

Curlee, Richard M.; Tuthill, Clinton D.; Watkins, Randall D.

1991-01-01

The method of producing a hermetic stable structural bond between quartz crystals includes providing first and second quartz crystals and depositing thin films of borosilicate glass and silicon on portions of the first and second crystals, respectively. The portions of the first and second crystals are then juxtaposed in a surface contact relationship and heated to a temperature for a period sufficient to cause the glass and silicon films to become electrically conductive. An electrical potential is then applied across the first and second crystals for creating an electrostatic field between the adjoining surfaces and causing the juxtaposed portions to be attracted into an intimate contact and form a bond for joining the adjoining surfaces of the crystals.

Nonequilibrium approach regarding metals from a linearised kappa distribution

NASA Astrophysics Data System (ADS)

Domenech-Garret, J. L.

2017-10-01

The widely used kappa distribution functions develop high-energy tails through an adjustable kappa parameter. The aim of this work is to show that such a parameter can itself be regarded as a function, which entangles information about the sources of disequilibrium. We first derive and analyse an expanded Fermi-Dirac kappa distribution. Later, we use this expanded form to obtain an explicit analytical expression for the kappa parameter of a heated metal on which an external electric field is applied. We show that such a kappa index causes departures from equilibrium depending on the physical magnitudes. Finally, we study the role of temperature and electric field on such a parameter, which characterises the electron population of a metal out of equilibrium.

A new type of localized fast moving electronic excitations in molecular chains

NASA Astrophysics Data System (ADS)

Korshunova, A. N.; Lakhno, V. D.

2014-06-01

It is shown that in a Holstein molecular chain placed in a strong longitudinal electric field some new types of excitations can arise. These excitations can transfer a charge over large distance (more than 1000 nucleotide pairs) along the chain retaining approximately their shapes. Excitations are formed only when a strong electric field either exists or quickly arises under especially preassigned conditions. These excitations transfer a charge even in the case when Holstein polarons are practically immobile. The results obtained are applied to synthetic homogeneous PolyG/PolyC DNA duplexes. They can also be provide the basis for explanation of famous H.W. Fink and C. Schönenberger experiment on long-range charge transfer in DNA.

Transverse circular-polarized Bessel beam generation by inward cylindrical aperture distribution.

PubMed

Pavone, S C; Ettorre, M; Casaletti, M; Albani, M

2016-05-16

In this paper the focusing capability of a radiating aperture implementing an inward cylindrical traveling wave tangential electric field distribution directed along a fixed polarization unit vector is investigated. In particular, it is shown that such an aperture distribution generates a non-diffractive Bessel beam whose transverse component (with respect to the normal of the radiating aperture) of the electric field takes the form of a zero-th order Bessel function. As a practical implementation of the theoretical analysis, a circular-polarized Bessel beam launcher, made by a radial parallel plate waveguide loaded with several slot pairs, arranged on a spiral pattern, is designed and optimized. The proposed launcher performance agrees with the theoretical model and exhibits an excellent polarization purity.

Rotational spectrum of 14N 2 · H 35Cl and 14N 2 · H 37Cl: electric field gradients at the nitrogen nuclei

NASA Astrophysics Data System (ADS)

Kisiel, Z.; Pszczólkowski, L.; Fowler, P. W.; Legon, A. C.

1997-09-01

Rotational spectra of the most abundant isotopic species of the weakly bound dimer formed between dinitrogen and hydrogen chloride were investigated. Spectroscopic constants for 14N 2 · H 37Cl were determined for the first time and those for 14N 2 · H 35Cl improved. Analysis of observed nuclear quadrupole spliting patterns within the framework of coupling of three nonequivalent nuclear spins allowed determination of splitting constants for both nuclei in the complexed dinitrogen molecule. Electric field gradient calculations at the SCF supermolecule level for the dimer are presented and account for the observed values of the nitrogen splitting constants.

Saturation of the Electric Field Transmitted to the Magnetosphere

NASA Technical Reports Server (NTRS)

Lyatsky, Wladislaw; Khazanov, George V.; Slavin, James A.

2010-01-01

We reexamined the processes leading to saturation of the electric field, transmitted into the Earth's ionosphere from the solar wind, incorporating features of the coupled system previously ignored. We took into account that the electric field is transmitted into the ionosphere through a region of open field lines, and that the ionospheric conductivity in the polar cap and auroral zone may be different. Penetration of the electric field into the magnetosphere is linked with the generation of the Alfven wave, going out from the ionosphere into the solar wind and being coupled with the field-aligned currents at the boundary of the open field limes. The electric field of the outgoing Alfven wave reduces the original electric field and provides the saturation effect in the electric field and currents during strong geomagnetic disturbances, associated with increasing ionospheric conductivity. The electric field and field-aligned currents of this Alfven wave are dependent on the ionospheric and solar wind parameters and may significantly affect the electric field and field-aligned currents, generated in the polar ionosphere. Estimating the magnitude of the saturation effect in the electric field and field-aligned currents allows us to improve the correlation between solar wind parameters and resulting disturbances in the Earth's magnetosphere.

The strain capacitor: A novel energy storage device

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

Deb Shuvra, Pranoy; McNamara, Shamus, E-mail: shamus.mcnamara@louisville.edu

2014-12-15

A novel electromechanical energy storage device is reported that has the potential to have high energy densities. It can efficiently store both mechanical strain energy and electrical energy in the form of an electric field between the electrodes of a strain-mismatched bilayer capacitor. When the charged device is discharged, both the electrical and mechanical energy are extracted in an electrical form. The charge-voltage profile of the device is suitable for energy storage applications since a larger portion of the stored energy can be extracted at higher voltage levels compared to a normal capacitor. Its unique features include the potential formore » long lifetime, safety, portability, wide operating temperature range, and environment friendliness. The device can be designed to operate over varied operating voltage ranges by selecting appropriate materials and by changing the dimensions of the device. In this paper a finite element model of the device is developed to verify and demonstrate the potential of the device as an energy storage element. This device has the potential to replace conventional energy storage devices.« less

JPRS Report, Science & Technology, Optoelectronics--LCD & Related Material

DTIC Science & Technology

1991-01-17

bottom electrode of the element are formed by the Ta film. Then, the electric field is applied in the citric acid solution and an oxide film is formed on...world, and research utilizing liquid crystal display elements and liquid crystal spatial light modulators has increased explosively . A summary of...Photographic emulsion film has been utilized in the past as the modulation device. It is regrettable but, against the two-dimensional signal, the

Electroporation of cells using EM induction of ac fields by a magnetic stimulator

NASA Astrophysics Data System (ADS)

Chen, C.; Evans, J. A.; Robinson, M. P.; Smye, S. W.; O'Toole, P.

2010-02-01

This paper describes a method of effectively electroporating mammalian cell membranes with pulsed alternating-current (ac) electric fields at field strengths of 30-160 kV m-1. Although many in vivo electroporation protocols entail applying square wave or monotonically decreasing pulses via needles or electrode plates, relatively few have explored the use of pulsed ac fields. Following our previous study, which established the effectiveness of ac fields for electroporating cell membranes, a primary/secondary coil system was constructed to produce sufficiently strong electric fields by electromagnetic induction. The primary coil was formed from the applicator of an established transcranial magnetic stimulation (TMS) system, while the secondary coil was a purpose-built device of a design which could eventually be implanted into tissue. The effects of field strength, pulse interval and cumulative exposure time were investigated using microscopy and flow cytometry. Results from experiments on concentrated cell suspensions showed an optimized electroporation efficiency of around 50%, demonstrating that electroporation can be practicably achieved by inducing such pulsed ac fields. This finding confirms the possibility of a wide range of in vivo applications based on magnetically coupled ac electroporation.

Relativistic many-body bound systems: electromagnetic properties. Monograph report

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

Danos, M.; Gillet, V.

1977-04-01

The formulae for the calculation of the electron scattering form factors, and of the static magnetic dipole and electric quadrupole moments, of relativistic many-body bound systems are derived. The framework, given in NBS Monograph 147, is relativistic quantum field theory in the Schrodinger picture; the physical particles, i.e., the solutions of the interacting fields, are given as linear combinations of the solutions of the free fields, called the parton fields. The parton--photon interaction is taken as given by minimal coupling. In addition, the contribution of the photon--vector meson vertex of the vector dominance model is derived.

Teaching Bohr Theory.

ERIC Educational Resources Information Center

Latimer, Colin J.

1983-01-01

Discusses some lesser known examples of atomic phenomena to illustrate to students that the old quantum theory in its simplest (Bohr) form is not an antiquity but can still make an important contribution to understanding such phenomena. Topics include hydrogenic/non-hydrogenic spectra and atoms in strong electric and magnetic fields. (Author/JN)

Shear flow of one-component polarizable fluid in a strong electric field

NASA Astrophysics Data System (ADS)

Sun, J. M.; Tao, R.

1996-04-01

A shear flow of one-component polarizable fluid in a strong electric field has a structural transition at a critical shear stress. When the shear stress is increased from zero up to the critical shear stress, the flow (in the x direction) has a flowing-chain (FC) structure, consisting of tilted or broken chains along the field (z direction). At the critical shear stress, the FC structure gives way to a flowing-hexagonal-layered (FHL) structure, consisting of several two-dimensional layers which are parallel to the x-z plane. Within one layer, particles form strings in the flow direction. Strings are constantly sliding over particles in strings right beneath. The effective viscosity drops dramatically at the structural change. As the shear stress reduces, the FHL structure persists even under a stress-free state if the thermal fluctuation is very weak. This structure change in the charging and discharging process produces a large hysteresis.

Agricultural and Food Processing Applications of Pulsed Power Technology

NASA Astrophysics Data System (ADS)

Takaki, Koichi; Ihara, Satoshi

Recent progress of agricultural and food processing applications of pulsed power is described in this paper. Repetitively operated compact pulsed power generators with a moderate peak power have been developed for the agricultural and the food processing applications. These applications are mainly based on biological effects and can be categorized as decontamination of air and liquid, germination promotion, inhabitation of saprophytes growth, extraction of juice from fruits and vegetables, and fertilization of liquid medium, etc. Types of pulsed power that have biological effects are caused with gas discharges, water discharges, and electromagnetic fields. The discharges yield free radicals, UV radiation, intense electric field, and shock waves. Biologically based applications of pulsed power are performed by selecting the type that gives the target objects the adequate result from among these agents or byproducts. For instance, intense electric fields form pores on the cell membrane, which is called electroporation, or influence the nuclei.

Thermal Control Utilizing an Thermal Control Utilizing an Two-Phase Loop with High Heat Flux Source

NASA Technical Reports Server (NTRS)

Jeong, Seong-Il; Didion, Jeffrey

2004-01-01

The electric field applied in dielectric fluids causes an imbalance in the dissociation-recombination reaction generated free space charges. The generated charges are redistributed by the applied electric field resulting in the heterocharge layers in the Vicinity of the electrodes. Proper design of the electrodes generates net axial flow motion pumping the fluid. The electrohydrodynamic (EHD) conduction pump is a new device that pumps dielectric fluids utilizing heterocharge layers formed by imposition of electrostatic fields. This paper evaluates the experimental performance of a two-phase breadboard thermal control loop consisting of an EHD conduction pump, condenser, pre-heater, high heat flux evaporator (HE), transport lines, and reservoir (accumulator). The generated pressure head and the maximum applicable heat flux are experimentally determined at various applied voltages and sink temperatures. Recovery from dryout condition by increasing the applied voltage to the pump is also demonstrated.

Laser-driven electron acceleration in a plasma channel with an additional electric field

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

Cheng, Li-Hong; Xue, Ju-Kui, E-mail: xuejk@nwnu.edu.cn; Liu, Jie, E-mail: liu-jie@iapcm.ac.cn

2016-05-15

We examine the electron acceleration in a two-dimensional plasma channel under the action of a laser field and an additional static electric field. We propose to design an appropriate additional electric field (its direction and location), in order to launch the electron onto an energetic trajectory. We find that the electron acceleration strongly depends on the coupled effects of the laser polarization, the direction, and location of the additional electric field. The additional electric field affects the electron dynamics by changing the dephasing rate. Particularly, a suitably designed additional electric field leads to a considerable energy gain from the lasermore » pulse after the interaction with the additional electric field. The electron energy gain from the laser with the additional electric field can be much higher than that without the additional electric field. This engineering provides a possible means for producing high energetic electrons.« less

“Beating speckles” via electrically-induced vibrations of Au nanorods embedded in sol-gel

PubMed Central

Ritenberg, Margarita; Beilis, Edith; Ilovitsh, Asaf; Barkai, Zehava; Shahmoon, Asaf; Richter, Shachar; Zalevsky, Zeev; Jelinek, Raz

2014-01-01

Generation of macroscopic phenomena through manipulating nano-scale properties of materials is among the most fundamental goals of nanotechnology research. We demonstrate cooperative “speckle beats” induced through electric-field modulation of gold (Au) nanorods embedded in a transparent sol-gel host. Specifically, we show that placing the Au nanorod/sol-gel matrix in an alternating current (AC) field gives rise to dramatic modulation of incident light scattered from the material. The speckle light patterns take form of “beats”, for which the amplitude and frequency are directly correlated with the voltage and frequency, respectively, of the applied AC field. The data indicate that the speckle beats arise from localized vibrations of the gel-embedded Au nanorods, induced through the interactions between the AC field and the electrostatically-charged nanorods. This phenomenon opens the way for new means of investigating nanoparticles in constrained environments. Applications in electro-optical devices, such as optical modulators, movable lenses, and others are also envisaged. PMID:24413086

Apparatus and method for laser beam diagnosis

DOEpatents

Salmon, Jr., Joseph T.

1991-01-01

An apparatus and method is disclosed for accurate, real time monitoring of the wavefront curvature of a coherent laser beam. Knowing the curvature, it can be quickly determined whether the laser beam is collimated, or focusing (converging), or de-focusing (diverging). The apparatus includes a lateral interferometer for forming an interference pattern of the laser beam to be diagnosed. The interference pattern is imaged to a spatial light modulator (SLM), whose output is a coherent laser beam having an image of the interference pattern impressed on it. The SLM output is focused to obtain the far-field diffraction pattern. A video camera, such as CCD, monitors the far-field diffraction pattern, and provides an electrical output indicative of the shape of the far-field pattern. Specifically, the far-field pattern comprises a central lobe and side lobes, whose relative positions are indicative of the radius of curvature of the beam. The video camera's electrical output may be provided to a computer which analyzes the data to determine the wavefront curvature of the laser beam.

Apparatus and method for laser beam diagnosis

DOEpatents

Salmon, J.T. Jr.

1991-08-27

An apparatus and method are disclosed for accurate, real time monitoring of the wavefront curvature of a coherent laser beam. Knowing the curvature, it can be quickly determined whether the laser beam is collimated, or focusing (converging), or de-focusing (diverging). The apparatus includes a lateral interferometer for forming an interference pattern of the laser beam to be diagnosed. The interference pattern is imaged to a spatial light modulator (SLM), whose output is a coherent laser beam having an image of the interference pattern impressed on it. The SLM output is focused to obtain the far-field diffraction pattern. A video camera, such as CCD, monitors the far-field diffraction pattern, and provides an electrical output indicative of the shape of the far-field pattern. Specifically, the far-field pattern comprises a central lobe and side lobes, whose relative positions are indicative of the radius of curvature of the beam. The video camera's electrical output may be provided to a computer which analyzes the data to determine the wavefront curvature of the laser beam. 11 figures.

Direct observation of spin-quadrupolar excitations in Sr2CoGe2O7 by high-field electron spin resonance

NASA Astrophysics Data System (ADS)

Akaki, Mitsuru; Yoshizawa, Daichi; Okutani, Akira; Kida, Takanori; Romhányi, Judit; Penc, Karlo; Hagiwara, Masayuki

2017-12-01

Exotic spin-multipolar ordering in spin transition metal insulators has so far eluded unambiguous experimental observation. A less studied, but perhaps more feasible fingerprint of multipole character emerges in the excitation spectrum in the form of quadrupolar transitions. Such multipolar excitations are desirable as they can be manipulated with the use of light or electric field and can be captured by means of conventional experimental techniques. Here we study single crystals of multiferroic Sr2CoGe2O7 and observe a two-magnon spin excitation appearing above the saturation magnetic field in electron spin resonance (ESR) spectra. Our analysis of the selection rules reveals that this spin excitation mode does not couple to the magnetic component of the light, but it is excited by the electric field only, in full agreement with the theoretical calculations. Due to the nearly isotropic nature of Sr2CoGe2O7 , we identify this excitation as a purely spin-quadrupolar two-magnon mode.

Human perception of electric fields and ion currents associated with high-voltage DC transmission lines.

PubMed

Blondin, J P; Nguyen, D H; Sbeghen, J; Goulet, D; Cardinal, C; Maruvada, P S; Plante, M; Bailey, W H

1996-01-01

The objective of this study was to assess the ability of humans to detect the presence of DC electric field and ion currents. An exposure chamber simulating conditions present in the vicinity of high-voltage DC (HVDC) lines was designed and built for this purpose. In these experiments, the facility was used to expose observers to DC electric fields up to 50 kV/m and ion current densities up to 120 nA/m2. Forty-eight volunteers (25 women and 23 men) between the ages of 18 and 57 years served as observers. Perception of DC fields was examined by using two psychophysical methods: an adaptive staircase procedure and a rating method derived from signal-detection theory. Subjects completed three different series of observations by using each of these methods; one was conducted without ion currents, and the other two involved various combinations of electric fields and ion currents. Overall, subjects were significantly more likely to detect DC fields as the intensity increased. Observers were able to detect the presence of DC fields alone, but only at high intensities; the average threshold was 45 kV/m. Except in the most sensitive individuals, ion current densities up to 60 nA/m2 did not significantly facilitate the detection of DC fields. However, higher ion current densities were associated with a substantial lowering of sensory thresholds in a large majority of observers. Data analysis also revealed large variations in perceptual thresholds among observers. Normative data indicating DC field and ion current intensities that can be detected by 50% of all observers are provided. In addition, for the most sensitive observers, several other detection proportions were derived from the distribution of individual detection capabilities. These data can form the basis for environmental guidelines relating to the design of HVDC lines.

Observed Enhancement of Reflectivity and Electric Field in Long-Lived Florida Anvils

NASA Technical Reports Server (NTRS)

Dye, James E.; Willett, John C.

2007-01-01

A study of two long-lived Florida anvils showed that reflectivity >20 dBZ increased in area, thickness and sometimes magnitude at mid-level well downstream of the convective cores. In these same regions electric fields maintained strengths >10 kV m1 for many tens of minutes and became quite uniform over tens of kilometers. Millimetric aggregates persisted at 9 to 10 km for extended times and distances. Aggregation of ice particles enhanced by strong electric fields might have contributed to reflectivity growth in the early anvil, but is unlikely to explain observations further out in the anvil. The enhanced reflectivity and existence of small, medium and large ice particles far out into the anvil suggest that an updraft was acting, perhaps in weak convective cells formed by instability generated from the evaporation and melting of falling ice particles. We conclude that charge separation must have occurred in these anvils, perhaps at the melting level but also at higher altitudes, in order to maintain fields >10 kV m 1 at 9 to 10 km for extended periods of time over large distances. We speculate that charge separation occurred as a result of ice-ice particle collisions (without supercooled water being present) via either a non-inductive or perhaps even an inductive mechanism, given the observed broad ice particle spectra, the strong pre-existing electric fields and the many tens of minutes available for particle interactions. The observations, particularly in the early anvil, show that the charge structure in these anvils was quite complex.

Ionospheric modification using relativistic electron beams

NASA Technical Reports Server (NTRS)

Banks, Peter M.; Fraser-Smith, Anthony C.; Gilchrist, B. E.

1990-01-01

The recent development of comparatively small electron linear accelerators (linacs) now makes possible a new class of ionospheric modification experiments using beams of relativistic electrons. These experiments can potentially provide much new information about the interactions of natural relativistic electrons with other particles in the upper atmosphere, and it may also make possible new forms of ionization structures extending down from the lower ionosphere into the largely un-ionized upper atmosphere. The consequences of firing a pulsed 1 A, 5 Mev electron beam downwards into the upper atmosphere are investigated. If a small pitch angle with respect to the ambient geomagnetic field is selected, the beam produces a narrow column of substantial ionization extending down from the source altitude to altitudes of approximately 40 to 45 km. This column is immediately polarized by the natural middle atmosphere fair weather electric field and an increasingly large potential difference is established between the column and the surrounding atmosphere. In the regions between 40 to 60 km, this potential can amount to many tens of kilovolts and the associated electric field can be greater than the field required for breakdown and discharge. Under these conditions, it may be possible to initiate lightning discharges along the initial ionization channel. Filamentation may also occur at the lower end to drive further currents in the partially ionized gases of the stratosphere. Such discharges would derive their energy from the earth-ionosphere electrical system and would be sustained until plasma depletion and/or electric field reduction brought the discharge under control. It is likely that this artificially-triggered lightning would produce measurable low-frequency radiation.

Engineering of oriented myocardium on three-dimensional micropatterned collagen-chitosan hydrogel.

PubMed

Chiu, Loraine L Y; Janic, Katarina; Radisic, Milica

2012-04-30

Surface topography and electrical field stimulation are important guidance cues that aid the organization and contractility of cardiomyocytes in vivo. We report here on the use of these biomimetic cues in vitro to engineer an implantable contractile cardiac tissue. Photocrosslinkable collagen-chitosan hydrogels with microgrooves of 10 µm, 20 µm and 100 µm in width were fabricated using polydimethylsiloxane (PDMS) molds. The hydrogels were seeded with cardiomyocytes, placed into a bioreactor array with the microgrooves aligned with the electrical field lines, and stimulated with biphasic square pulses at 1 Hz and 2.5 V/cm. At Day 6, cardiomyocytes were aligned in the direction of the microgrooves. When cultivated without electrical stimulation, the excitation threshold of engineered cardiac tissues using micropatterned hydrogels was significantly lower than using smooth hydrogels, thus showing the importance of cell alignment to cardiac function. The success rate of achieving beating constructs was higher with the application of electrical stimulation. In addition, formation of dense contractile cardiac organoids was observed in groups with both biomimetic cues. The cultivation of cardiomyocytes on hydrogels with 10 µm grooves yielded 100% beating tissues with or without electrical stimulation, thus suggesting a smaller groove width is necessary for cells to communicate and form proper gap junctions. However, electrical field stimulation further increased cell density and enhanced tissue morphology which may be essential for the integration of the tissue construct to the native heart tissue upon implantation. The biodegradability of the hydrogel substrate allows for the rapid translation of the engineered, oriented cardiac tissue to clinical applications.

Experimental investigation on the electrical contact behavior of rolling contact connector.

PubMed

Chen, Junxing; Yang, Fei; Luo, Kaiyu; Zhu, Mingliang; Wu, Yi; Rong, Mingzhe

2015-12-01

Rolling contact connector (RCC) is a new technology utilized in high performance electric power transfer systems with one or more rotating interfaces, such as radars, satellites, wind generators, and medical computed tomography machines. Rolling contact components are used in the RCC instead of traditional sliding contacts to transfer electrical power and/or signal. Since the requirement of the power transmission is increasing in these years, the rolling electrical contact characteristics become more and more important for the long-life design of RCC. In this paper, a typical form of RCC is presented. A series of experimental work are carried out to investigate the rolling electrical contact characteristics during its lifetime. The influence of a variety of factors on the electrical contact degradation behavior of RCC is analyzed under both vacuum and air environment. Based on the surface morphology and elemental composition changes in the contact zone, which are assessed by field emission scanning electron microscope and confocal laser scanning microscope, the mechanism of rolling electrical contact degradation is discussed.

Auroral zone electric fields from DE 1 and 2 at magnetic conjunctions

NASA Technical Reports Server (NTRS)

Weimer, D. R.; Goertz, C. K.; Gurnett, D. A.; Maynard, N. C.; Burch, J. L.

1985-01-01

Nearly simultaneous measurements of auroral zone electric fields are obtained by the Dynamics Explorer spacecraft at altitudes below 900 km and above 4,500 km during magnetic conjunctions. The measured electric fields are usually perpendicular to the magnetic field lines. The north-south meridional electric fields are projected to a common altitude by a mapping function which accounts for the convergence of the magnetic field lines. When plotted as a function of invariant latitude, graphs of the projected electric fields measured by both DE-1 and DE-2 show that the large-scale electric field is the same at both altitudes, as expected. Superimposed on the large-scale fields, however, are small-scale features with wavelengths less than 100 km which are larger in magnitude at the higher altitude. Fourier transforms of the electric fields show that the magnitudes depend on wavelength. Outside of the auroral zone the electric field spectrums are nearly identical. But within the auroral zone the high and low altitude electric fields have a ratio which increases with the reciprocal of the wavelength. The small-scale electric field variations are associated with field-aligned currents. These currents are measured with both a plasma instrument and magnetometer on DE-1.

Single layer multi-color luminescent display and method of making

NASA Technical Reports Server (NTRS)

Robertson, James B. (Inventor)

1992-01-01

The invention is a multi-color luminescent display comprising an insulator substrate and a single layer of host material, which may be a phosphor deposited thereon that hosts one or more different impurities, therein forming a pattern of selected and distinctly colored phosphors such as blue, green, and red phosphors in a single layer of host material. Transparent electrical conductor means may be provided for subjecting selected portions of the pattern of colored phosphors to an electric field, thereby forming a multi-color, single layer electroluminescent display. A method of forming a multi-color luminescent display includes the steps of depositing on an insulator substrate a single layer of host material, which itself may be a phosphor, with the properties to host varying quantities of different impurities and introducing one or more of said different impurities into selected areas of the said single layer of host material by thermal diffusion or ion implantation to form a pattern of phosphors of different colors in the said single layer of host material.

Defect-free erbium silicide formation using an ultrathin Ni interlayer.

PubMed

Choi, Juyun; Choi, Seongheum; Kang, Yu-Seon; Na, Sekwon; Lee, Hoo-Jeong; Cho, Mann-Ho; Kim, Hyoungsub

2014-08-27

An ultrathin Ni interlayer (∼1 nm) was introduced between a TaN-capped Er film and a Si substrate to prevent the formation of surface defects during thermal Er silicidation. A nickel silicide interfacial layer formed at low temperatures and incurred uniform nucleation and the growth of a subsequently formed erbium silicide film, effectively inhibiting the generation of recessed-type surface defects and improving the surface roughness. As a side effect, the complete transformation of Er to erbium silicide was somewhat delayed, and the electrical contact property at low annealing temperatures was dominated by the nickel silicide phase with a high Schottky barrier height. After high-temperature annealing, the early-formed interfacial layer interacted with the growing erbium silicide, presumably forming an erbium silicide-rich Er-Si-Ni mixture. As a result, the electrical contact property reverted to that of the low-resistive erbium silicide/Si contact case, which warrants a promising source/drain contact application for future high-performance metal-oxide-semiconductor field-effect transistors.

Analysis of Surface Electric Field Measurements from an Array of Electric Field Mills

NASA Astrophysics Data System (ADS)

Lucas, G.; Thayer, J. P.; Deierling, W.

2016-12-01

Kennedy Space Center (KSC) has operated an distributed array of over 30 electric field mills over the past 18 years, providing a unique data set of surface electric field measurements over a very long timespan. In addition to the electric field instruments there are many meteorological towers around KSC that monitor the local meteorological conditions. Utilizing these datasets we have investigated and found unique spatial and temporal signatures in the electric field data that are attributed to local meteorological effects and the global electric circuit. The local and global scale influences on the atmospheric electric field will be discussed including the generation of space charge from the ocean surf, local cloud cover, and a local enhancement in the electric field that is seen at sunrise.

Transparent conductor-embedding nanocones for selective emitters: optical and electrical improvements of Si solar cells

PubMed Central

Kim, Joondong; Yun, Ju-Hyung; Kim, Hyunyub; Cho, Yunae; Park, Hyeong-Ho; Kumar, M. Melvin David; Yi, Junsin; Anderson, Wayne A.; Kim, Dong-Wook

2015-01-01

Periodical nanocone-arrays were employed in an emitter region for high efficient Si solar cells. Conventional wet-etching process was performed to form the nanocone-arrays for a large area, which spontaneously provides the graded doping features for a selective emitter. This enables to lower the electrical contact resistance and enhances the carrier collection due to the high electric field distribution through a nanocone. Optically, the convex-shaped nanocones efficiently reduce light-reflection and the incident light is effectively focused into Si via nanocone structure, resulting in an extremely improved the carrier collection performances. This nanocone-arrayed selective emitter simultaneously satisfies optical and electrical improvement. We report the record high efficiency of 16.3% for the periodically nanoscale patterned emitter Si solar cell. PMID:25787933

Transparent conductor-embedding nanocones for selective emitters: optical and electrical improvements of Si solar cells.

PubMed

Kim, Joondong; Yun, Ju-Hyung; Kim, Hyunyub; Cho, Yunae; Park, Hyeong-Ho; Kumar, M Melvin David; Yi, Junsin; Anderson, Wayne A; Kim, Dong-Wook

2015-03-19

Periodical nanocone-arrays were employed in an emitter region for high efficient Si solar cells. Conventional wet-etching process was performed to form the nanocone-arrays for a large area, which spontaneously provides the graded doping features for a selective emitter. This enables to lower the electrical contact resistance and enhances the carrier collection due to the high electric field distribution through a nanocone. Optically, the convex-shaped nanocones efficiently reduce light-reflection and the incident light is effectively focused into Si via nanocone structure, resulting in an extremely improved the carrier collection performances. This nanocone-arrayed selective emitter simultaneously satisfies optical and electrical improvement. We report the record high efficiency of 16.3% for the periodically nanoscale patterned emitter Si solar cell.

Preliminary Findings from the One-Year Electric Field Study in the North Slope of Alaska (OYES-NSA), Atmospheric Radiation Measurement (ARM) Field Campaign

NASA Astrophysics Data System (ADS)

Lavigne, T.; Liu, C.

2017-12-01

Previous studies focusing on the comparison of the measured electric field to the physical properties of global electrified clouds have been conducted almost exclusively in the Southern Hemisphere. The One-Year Electric Field Study-North Slope of Alaska (OYES-NSA) aims to establish a long-running collection of this valuable electric field data in the Northern Hemisphere. Presented here is the six-month preliminary data and results of the OYES-NSA Atmospheric Radiation Mission (ARM) field campaign. The local electric field measured in Barrow, Alaska using two CS110 reciprocating shutter field meters, has been compared to simultaneous measurements from the ARM Ka-Band zenith radar, to better understand the influence and contribution of different types of clouds on the local electric field. The fair-weather electric field measured in Barrow has also been analyzed and compared to the climatology of electric field at Vostok Station, Antarctica. The combination of the electric field dataset in the Northern Hemisphere, alongside the local Ka cloud radar, global Precipitation Feature (PF) database, and quasi-global lightning activity (55oN-55oS), allows for advances in the physical understanding of the local electric field, as well as the Global Electric Circuit (GEC).

The physical foundation of the reconnection electric field

NASA Astrophysics Data System (ADS)

Hesse, M.; Liu, Y.-H.; Chen, L.-J.; Bessho, N.; Wang, S.; Burch, J. L.; Moretto, T.; Norgren, C.; Genestreti, K. J.; Phan, T. D.; Tenfjord, P.

2018-03-01

Magnetic reconnection is a key charged particle transport and energy conversion process in environments ranging from astrophysical systems to laboratory plasmas [Yamada et al., Rev. Mod. Phys. 82, 603-664 (2010)]. Magnetic reconnection facilitates plasma transport by establishing new connections of magnetic flux tubes, and it converts, often explosively, energy stored in the magnetic field to kinetic energy of charged particles [J. L. Burch and J. F. Drake, Am. Sci. 97, 392-299 (2009)]. The intensity of the magnetic reconnection process is measured by the reconnection electric field, which regulates the rate of flux tube connectivity changes. The change of magnetic connectivity occurs in the current layer of the diffusion zone, where the plasma transport is decoupled from the transport of magnetic flux. Here we report on computer simulations and analytic theory to provide a self-consistent understanding of the role of the reconnection electric field, which extends substantially beyond the simple change of magnetic connections. Rather, we find that the reconnection electric field is essential to maintain the current density in the diffusion region, which would otherwise be dissipated by a set of processes. Natural candidates for current dissipation are the average convection of current carriers away from the reconnection region by the outflow of accelerated particles, or the average rotation of the current density by the magnetic field reversal in the vicinity. Instead, we show here that the current dissipation is the result of thermal effects, underlying the statistical interaction of current-carrying particles with the adjacent magnetic field. We find that this interaction serves to redirect the directed acceleration of the reconnection electric field to thermal motion. This thermalization manifests itself in form of quasi-viscous terms in the thermal energy balance of the current layer. This collisionless viscosity, found in the pressure evolution equation, dominates near the x-line. These quasi-viscous terms act to increase the average thermal energy. Our predictions regarding current and thermal energy balance are readily amenable to exploration in the laboratory or by satellite missions, in particular, by NASA's Magnetospheric Multiscale mission.

Transient Torque Method: A Fast and Nonintrusive Technique to Simultaneously Determine Viscosity and Electrical Conductivity of Semiconducting and Metallic Melts

NASA Technical Reports Server (NTRS)

Li, C.; Ban, H.; Lin, B.; Scripa, R. N.; Su, C.-H.; Lehoczky, S. L.; Zhu, S.

2004-01-01

A transient torque method was developed to rapidly and simultaneously determine the viscosity and electrical conductivity of liquid metals and molten semiconductors. The experimental setup of the transient torque method is similar to that of the oscillation cup method. The melt sample is sealed inside a fused silica ampoule, and the ampoule is suspended by a long quartz fiber to form a torsional oscillation system. A rotating magnetic field is used to induce a rotating flow in the conductive melt, which causes the ampoule to rotate around its vertical axis. A sensitive angular detector is used to measure the deflection angle of the ampoule. Based on the transient behavior of the deflection angle as the rotating magnetic field is applied, the electrical conductivity and viscosity of the melt can be obtained simultaneously by numerically fitting the data to a set of governing equations. The transient torque viscometer was applied successfully to measure the viscosity and electrical conductivity of high purity mercury at 53.4 C. The results were in excellent agreement with published data. The method is nonintrusive; capable of rapid measurement of the viscosity of toxic, high vapor pressure melts at elevated temperatures. In addition, the transient torque viscometer can also be operated as an oscillation cup viscometer to measure just the viscosity of the melt or as a rotating magnetic field method to determine the electrical conductivity of a melt or a solid if desired.

Non-neutral plasma diode in the presence of a transverse magnetic field

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

Pramanik, Sourav; Chakrabarti, Nikhil; Kuznetsov, V. I.

An analytical study of the plasma states in non-neutral plasma diodes in the presence of an external transverse magnetic field is presented for an arbitrary neutralization parameter γ. Considerations are restricted to the regime where no electrons are turned around by the magnetic field. The emitter electric field strength E{sub 0} is used as a characteristic function to investigate the existence of solutions depending on the diode length, the applied voltage, the neutralization parameter, and the magnetic field strength. The potential distribution has a wave form for small magnitudes of the external magnetic field, as well as for the casemore » when magnetic field is absent. A new family of solutions appears along with the Bursian ones. On the other hand, as the Larmor radius becomes comparable with the beam Debye length, oscillations in the potential disappear, and only the Bursian branches remain. Unlike the vacuum diode, there are steady state solutions for the negative values of the emitter field strength. As the neutralization parameter (γ) increases, the emitter field strength relating to the SCL (space charge limit) bifurcation point diminishes, and at γ > 1, the value of the emitter's electric field strength at the space charge limit (E{sub 0,SCL}) turns out to be negative.« less

Electrically generated eddies at an eightfold stagnation point within a nanopore

PubMed Central

Sherwood, J. D.; Mao, M.; Ghosal, S.

2014-01-01

Electrically generated flows around a thin dielectric plate pierced by a cylindrical hole are computed numerically. The geometry represents that of a single nanopore in a membrane. When the membrane is uncharged, flow is due solely to induced charge electroosmosis, and eddies are generated by the high fields at the corners of the nanopore. These eddies meet at stagnation points. If the geometry is chosen correctly, the stagnation points merge to form a single stagnation point at which four streamlines cross at a point and eight eddies meet. PMID:25489206

High energy neutron dosimeter

DOEpatents

Sun, Rai Ko S.F.

1994-01-01

A device for measuring dose equivalents in neutron radiation fields. The device includes nested symmetrical hemispheres (forming spheres) of different neutron moderating materials that allow the measurement of dose equivalents from 0.025 eV to past 1 GeV. The layers of moderating material surround a spherical neutron counter. The neutron counter is connected by an electrical cable to an electrical sensing means which interprets the signal from the neutron counter in the center of the moderating spheres. The spherical shape of the device allows for accurate measurement of dose equivalents regardless of its positioning.

Nano-multiplication region avalanche photodiodes and arrays

NASA Technical Reports Server (NTRS)

Zheng, Xinyu (Inventor); Pain, Bedabrata (Inventor); Cunningham, Thomas J. (Inventor)

2011-01-01

An avalanche photodiode with a nano-scale reach-through structure comprising n-doped and p-doped regions, formed on a silicon island on an insulator, so that the avalanche photodiode may be electrically isolated from other circuitry on other silicon islands on the same silicon chip as the avalanche photodiode. For some embodiments, multiplied holes generated by an avalanche reduces the electric field in the depletion region of the n-doped and p-doped regions to bring about self-quenching of the avalanche photodiode. Other embodiments are described and claimed.

An all-diamond, hermetic electrical feedthrough array for a retinal prosthesis.

PubMed

Ganesan, Kumaravelu; Garrett, David J; Ahnood, Arman; Shivdasani, Mohit N; Tong, Wei; Turnley, Ann M; Fox, Kate; Meffin, Hamish; Prawer, Steven

2014-01-01

The interface between medical implants and the human nervous system is rapidly becoming more and more complex. This rise in complexity is driving the need for increasing numbers of densely packed electrical feedthrough to carry signals to and from implanted devices. This is particularly crucial in the field of neural prosthesis where high resolution stimulating or recording arrays near peripheral nerves or in the brain could dramatically improve the performance of these devices. Here we describe a flexible strategy for implementing high density, high count arrays of hermetic electrical feedthroughs by forming conducting nitrogen doped nanocrystalline diamond channels within an insulating polycrystalline diamond substrate. A unique feature of these arrays is that the feedthroughs can themselves be used as stimulating electrodes for neural tissue. Our particular application is such a feedthrough, designed as a component of a retinal implant to restore vision to the blind. The hermeticity of the feedthroughs means that the array can also form part of an implantable capsule which can interface directly with internal electronic chips. The hermeticity of the array is demonstrated by helium leak tests and electrical and electrochemical characterisation of the feedthroughs is described. The nitrogen doped nanocrystalline diamond forming the electrical feedthroughs is shown to be non-cyctotoxic. New fabrication strategies, such as the one described here, combined with the exceptional biostability of diamond can be exploited to generate a range of biomedical implants that last for the lifetime of the user without fear of degradation.

Rapid Microfluidic Mixers Utilizing Dispersion Effect and Interactively Time-Pulsed Injection

NASA Astrophysics Data System (ADS)

Leong, Jik-Chang; Tsai, Chien-Hsiung; Chang, Chin-Lung; Lin, Chiu-Feng; Fu, Lung-Ming

2007-08-01

In this paper, we present a novel active microfluidic mixer utilizing a dispersion effect in an expansion chamber and applying interactively time-pulsed driving voltages to the respective inlet fluid flows to induce electroosmotic flow velocity variations for developing a rapid mixing effect in a microchannel. Without using any additional equipment to induce flow perturbations, only a single high-voltage power source is required for simultaneously driving and mixing sample fluids, which results in a simple and low-cost system for mixing. The effects of the applied main electrical field, interactive frequency, and expansion ratio on the mixing performance are thoroughly examined experimentally and numerically. The mixing ratio can be as high as 95% within a mixing length of 3000 μm downstream from the secondary T-form when a driving electric field strength of 250 V/cm, a periodic switching frequency of 5 Hz, and the expansion ratio M=1:10 are applied. In addition, the optimization of the driving electric field, switching frequency, expansion ratio, expansion entry length, and expansion chamber length for achieving a maximum mixing ratio is also discussed in this study. The novel method proposed in this study can be used for solving the mixing problem in the field of micro-total-analysis systems in a simple manner.

Mechanical Enhancement of Sensitivity in Natural Rubber Using Electrolytic Polymerization Aided by a Magnetic Field and MCF for Application in Haptic Sensors

PubMed Central

Shimada, Kunio; Saga, Norihiko

2016-01-01

Sensors are essential to the fulfillment of every condition of haptic technology, and they need simultaneously to sense shear stress as well as normal force, and temperature. They also must have a strong and simple structure, softness, and large extension. To achieve these conditions simultaneously, we enhanced the sensitivity of sensors utilizing natural rubber (NR)-latex through the application of electrolytic polymerization focused on the isoprene C=C bonds in natural rubbers such as NR-latex, and then applied a magnetic field and magnetic compound fluid (MCF) as magnetically responsive fluid. When an electric field alone was used in the rubber, the effect of electrolytic polymerization was very small compared to the effect in well-known conductive polymer solution such as plastic. The MCF developed by Shimada in 2001 involved magnetite and metal particles, and acts as a filler in NR-latex. By utilizing the magnetic, electric fields and the MCF, we aligned the electrolytically polymerized C=C along the magnetic field line with the magnetic clusters formed by the aggregation of magnetite and metal particles so as to enhance the effect of electrolytic polymerization. We then demonstrated the effectiveness of the new method of rubber vulcanization on the sensitivity of the rubber by experimentally investigating its electric and dynamic characteristics. PMID:27649210

Structure of the floating water bridge and water in an electric field

PubMed Central

Skinner, Lawrie B.; Benmore, Chris J.; Shyam, Badri; Weber, J. K. R.; Parise, John B.

2012-01-01

The floating water bridge phenomenon is a freestanding rope-shaped connection of pure liquid water, formed under the influence of a high potential difference (approximately 15 kV). Several recent spectroscopic, optical, and neutron scattering studies have suggested that the origin of the bridge is associated with the formation of anisotropic chains of water molecules in the liquid. In this work, high energy X-ray diffraction experiments have been performed on a series of floating water bridges as a function of applied voltage, bridge length, and position within the bridge. The two-dimensional X-ray scattering data showed no direction-dependence, indicating that the bulk water molecules do not exhibit any significant preferred orientation along the electric field. The only structural changes observed were those due to heating, and these effects were found to be the same as for bulk water. These X-ray scattering measurements are supported by molecular dynamics (MD) simulations which were performed under electric fields of 106 V/m and 109 V/m. Directional structure factor calculations were made from these simulations parallel and perpendicular to the E-field. The 106 V/m model showed no significant directional-dependence (anisotropy) in the structure factors. The 109 V/m model however, contained molecules aligned by the E-field, and had significant structural anisotropy. PMID:23010930

Mechanical Enhancement of Sensitivity in Natural Rubber Using Electrolytic Polymerization Aided by a Magnetic Field and MCF for Application in Haptic Sensors.

PubMed

Shimada, Kunio; Saga, Norihiko

2016-09-18

Sensors are essential to the fulfillment of every condition of haptic technology, and they need simultaneously to sense shear stress as well as normal force, and temperature. They also must have a strong and simple structure, softness, and large extension. To achieve these conditions simultaneously, we enhanced the sensitivity of sensors utilizing natural rubber (NR)-latex through the application of electrolytic polymerization focused on the isoprene C=C bonds in natural rubbers such as NR-latex, and then applied a magnetic field and magnetic compound fluid (MCF) as magnetically responsive fluid. When an electric field alone was used in the rubber, the effect of electrolytic polymerization was very small compared to the effect in well-known conductive polymer solution such as plastic. The MCF developed by Shimada in 2001 involved magnetite and metal particles, and acts as a filler in NR-latex. By utilizing the magnetic, electric fields and the MCF, we aligned the electrolytically polymerized C=C along the magnetic field line with the magnetic clusters formed by the aggregation of magnetite and metal particles so as to enhance the effect of electrolytic polymerization. We then demonstrated the effectiveness of the new method of rubber vulcanization on the sensitivity of the rubber by experimentally investigating its electric and dynamic characteristics.

Ground and CHAMP observations of field-aligned current circuits generated by lower atmospheric disturbances and expectations to the SWARM to clarify their three dimensional structure

NASA Astrophysics Data System (ADS)

Iyemori, Toshihiko; Nakanishi, Kunihito; Aoyama, Tadashi; Lühr, Hermann

2014-05-01

Acoustic gravity waves propagated to the ionosphere cause dynamo currents in the ionosphere. They divert along geomagnetic field lines of force to another hemisphere accompanying electric field and then flow in the ionosphere of another hemisphere by the electric field forming closed current circuits. The oscillating current circuits with the period of acoustic waves generate magnetic variations on the ground, and they are observed as long period geomagnetic pulsations. This effect has been detected during big earthquakes, strong typhoons, tornados etc. On a low-altitude satellite orbit, the spatial distribution (i.e., structure) of the current circuits along the satellite orbit should be detected as temporal magnetic oscillations, and the effect is confirmed by a CHAMP data analysis. On the spatial structure, in particular, in the longitudinal direction, it has been difficult to examine by a single satellite or from ground magnetic observations. The SWARM satellites will provide an unique opportunity to clarify the three dimensional structure of the field-aligned current circuits.

THE MECHANISMS OF ELECTRON ACCELERATION DURING MULTIPLE X LINE MAGNETIC RECONNECTION WITH A GUIDE FIELD

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

Wang, Huanyu; Lu, Quanming; Huang, Can

2016-04-20

The interactions between magnetic islands are considered to play an important role in electron acceleration during magnetic reconnection. In this paper, two-dimensional particle-in-cell simulations are performed to study electron acceleration during multiple X line reconnection with a guide field. Because the electrons remain almost magnetized, we can analyze the contributions of the parallel electric field, Fermi, and betatron mechanisms to electron acceleration during the evolution of magnetic reconnection through comparison with a guide-center theory. The results show that with the magnetic reconnection proceeding, two magnetic islands are formed in the simulation domain. Next, the electrons are accelerated by both themore » parallel electric field in the vicinity of the X lines and the Fermi mechanism due to the contraction of the two magnetic islands. Then, the two magnetic islands begin to merge into one, and, in such a process, the electrons can be accelerated by both the parallel electric field and betatron mechanisms. During the betatron acceleration, the electrons are locally accelerated in the regions where the magnetic field is piled up by the high-speed flow from the X line. At last, when the coalescence of the two islands into one big island finishes, the electrons can be further accelerated by the Fermi mechanism because of the contraction of the big island. With the increase of the guide field, the contributions of the Fermi and betatron mechanisms to electron acceleration become less and less important. When the guide field is sufficiently large, the contributions of the Fermi and betatron mechanisms are almost negligible.« less

Neuron matters: electric activation of neuronal tissue is dependent on the interaction between the neuron and the electric field.

PubMed

Ye, Hui; Steiger, Amanda

2015-08-12

In laboratory research and clinical practice, externally-applied electric fields have been widely used to control neuronal activity. It is generally accepted that neuronal excitability is controlled by electric current that depolarizes or hyperpolarizes the excitable cell membrane. What determines the amount of polarization? Research on the mechanisms of electric stimulation focus on the optimal control of the field properties (frequency, amplitude, and direction of the electric currents) to improve stimulation outcomes. Emerging evidence from modeling and experimental studies support the existence of interactions between the targeted neurons and the externally-applied electric fields. With cell-field interaction, we suggest a two-way process. When a neuron is positioned inside an electric field, the electric field will induce a change in the resting membrane potential by superimposing an electrically-induced transmembrane potential (ITP). At the same time, the electric field can be perturbed and re-distributed by the cell. This cell-field interaction may play a significant role in the overall effects of stimulation. The redistributed field can cause secondary effects to neighboring cells by altering their geometrical pattern and amount of membrane polarization. Neurons excited by the externally-applied electric field can also affect neighboring cells by ephaptic interaction. Both aspects of the cell-field interaction depend on the biophysical properties of the neuronal tissue, including geometric (i.e., size, shape, orientation to the field) and electric (i.e., conductivity and dielectricity) attributes of the cells. The biophysical basis of the cell-field interaction can be explained by the electromagnetism theory. Further experimental and simulation studies on electric stimulation of neuronal tissue should consider the prospect of a cell-field interaction, and a better understanding of tissue inhomogeneity and anisotropy is needed to fully appreciate the neural basis of cell-field interaction as well as the biological effects of electric stimulation.

Self-triggering superconducting fault current limiter

DOEpatents

Yuan, Xing [Albany, NY; Tekletsadik, Kasegn [Rexford, NY

2008-10-21

A modular and scaleable Matrix Fault Current Limiter (MFCL) that functions as a "variable impedance" device in an electric power network, using components made of superconducting and non-superconducting electrically conductive materials. The matrix fault current limiter comprises a fault current limiter module that includes a superconductor which is electrically coupled in parallel with a trigger coil, wherein the trigger coil is magnetically coupled to the superconductor. The current surge doing a fault within the electrical power network will cause the superconductor to transition to its resistive state and also generate a uniform magnetic field in the trigger coil and simultaneously limit the voltage developed across the superconductor. This results in fast and uniform quenching of the superconductors, significantly reduces the burnout risk associated with non-uniformity often existing within the volume of superconductor materials. The fault current limiter modules may be electrically coupled together to form various "n" (rows).times."m" (columns) matrix configurations.

Dyadic Green function for the electromagnetic field in mutilayered isotropic media - An operator approach

NASA Astrophysics Data System (ADS)

Sphicopoulos, T.; Teodoridis, V.; Gardiol, F. E.

1985-08-01

The dyadic Green functions of electric and magnetic type for multilayered isotropic media are discussed, and a tractable form is obtained by an operator method, which does not involve infinite sums of Hansen functions. The formulation considers a TE-TM decomposition and the use of propagation matrices. Special attention is given to the application of these functions to the analysis of problems in the field of nondestructive measurement of materials.

Simple estimation of induced electric fields in nervous system tissues for human exposure to non-uniform electric fields at power frequency

NASA Astrophysics Data System (ADS)

Tarao, Hiroo; Miyamoto, Hironobu; Korpinen, Leena; Hayashi, Noriyuki; Isaka, Katsuo

2016-06-01

Most results regarding induced current in the human body related to electric field dosimetry have been calculated under uniform field conditions. We have found in previous work that a contact current is a more suitable way to evaluate induced electric fields, even in the case of exposure to non-uniform fields. If the relationship between induced currents and external non-uniform fields can be understood, induced electric fields in nervous system tissues may be able to be estimated from measurements of ambient non-uniform fields. In the present paper, we numerically calculated the induced electric fields and currents in a human model by considering non-uniform fields based on distortion by a cubic conductor under an unperturbed electric field of 1 kV m-1 at 60 Hz. We investigated the relationship between a non-uniform external electric field with no human present and the induced current through the neck, and the relationship between the current through the neck and the induced electric fields in nervous system tissues such as the brain, heart, and spinal cord. The results showed that the current through the neck can be formulated by means of an external electric field at the central position of the human head, and the distance between the conductor and the human model. As expected, there is a strong correlation between the current through the neck and the induced electric fields in the nervous system tissues. The combination of these relationships indicates that induced electric fields in these tissues can be estimated solely by measurements of the external field at a point and the distance from the conductor.

Spherical Ethylene/Air Diffusion Flames Subject to Concentric DC Electric Field in Microgravity

NASA Technical Reports Server (NTRS)

Yuan, Z. -G.; Hegde, U.; Faeth, G. M.

2001-01-01

It is well known that microgravity conditions, by eliminating buoyant flow, enable many combustion phenomena to be observed that are not possible to observe at normal gravity. One example is the spherical diffusion flame surrounding a porous spherical burner. The present paper demonstrates that by superimposing a spherical electrical field on such a flame, the flame remains spherical so that we can study the interaction between the electric field and flame in a one-dimensional fashion. Flames are susceptible to electric fields that are much weaker than the breakdown field of the flame gases owing to the presence of ions generated in the high temperature flame reaction zone. These ions and the electric current of the moving ions, in turn, significantly change the distribution of the electric field. Thus, to understand the interplay between the electric field and the flame is challenging. Numerous experimental studies of the effect of electric fields on flames have been reported. Unfortunately, they were all involved in complex geometries of both the flow field and the electric field, which hinders detailed study of the phenomena. In a one-dimensional domain, however, the electric field, the flow field, the thermal field and the chemical species field are all co-linear. Thus the problem is greatly simplified and becomes more tractable.

Method of making dielectric capacitors with increased dielectric breakdown strength

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

Ma, Beihai; Balachandran, Uthamalingam; Liu, Shanshan

The invention is directed to a process for making a dielectric ceramic film capacitor and the ceramic dielectric laminated capacitor formed therefrom, the dielectric ceramic film capacitors having increased dielectric breakdown strength. The invention increases breakdown strength by embedding a conductive oxide layer between electrode layers within the dielectric layer of the capacitors. The conductive oxide layer redistributes and dissipates charge, thus mitigating charge concentration and micro fractures formed within the dielectric by electric fields.

Contact formation and gettering of precipitated impurities by multiple firing during semiconductor device fabrication

DOEpatents

Sopori, Bhushan

2014-05-27

Methods for contact formation and gettering of precipitated impurities by multiple firing during semiconductor device fabrication are provided. In one embodiment, a method for fabricating an electrical semiconductor device comprises: a first step that includes gettering of impurities from a semiconductor wafer and forming a backsurface field; and a second step that includes forming a front contact for the semiconductor wafer, wherein the second step is performed after completion of the first step.

Study of electric field distorted by space charges under positive lightning impulse voltage

NASA Astrophysics Data System (ADS)

Wang, Zezhong; Geng, Yinan

2018-03-01

Actually, many insulation problems are related to electric fields. And measuring electric fields is an important research topic of high-voltage engineering. In particular, the electric field distortion caused by space charge is the basis of streamer theory, and thus quantitatively measuring the Poisson electric field caused by space charge is significant to researching the mechanism of air gap discharge. In this paper, we used our photoelectric integrated sensor to measure the electric field distribution in a 1-m rod-plane gap under positive lightning impulse voltage. To verify the reliability of this quantitative measurement, we compared the measured results with calculated results from a numerical simulation. The electric-field time domain waveforms on the axis of the 1-m rod-plane out of the space charge zone were measured with various electrodes. The Poisson electric fields generated by space charge were separated from the Laplace electric field generated by applied voltages, and the amplitudes and variations were measured for various applied voltages and at various locations. This work also supplies the feasible basis for directly measuring strong electric field under high voltage.

Crystal-field effects in the kagome antiferromagnet Ho3Ru4Al12

NASA Astrophysics Data System (ADS)

Gorbunov, D. I.; Nomura, T.; Ishii, I.; Henriques, M. S.; Andreev, A. V.; Doerr, M.; Stöter, T.; Suzuki, T.; Zherlitsyn, S.; Wosnitza, J.

2018-05-01

In Ho3Ru4Al12 , the Ho atoms form a distorted kagome lattice. We performed magnetization, magnetic-susceptibility, specific-heat, and ultrasound measurements on a single crystal. We find that the magnetic and magnetoelastic properties of Ho3Ru4Al12 result from an interplay between geometric frustration and crystal-electric-field (CEF) effects. The Ho atoms order antiferromagnetically at TN=4.5 K with reduced magnetic moments. In applied field, the magnetization shows anomalies that can be explained by CEF level crossings. We propose a CEF level scheme for which the ground-state doublet and the first two excited singlets at about 2.7 K form a quasiquartet. Indirect interlevel transitions allow for a quadrupolar interaction. This interaction explains well changes in the elastic shear modulus C44 as a function of temperature and magnetic field.

Wireless Chemical Sensor and Sensing Method for Use Therewith

NASA Technical Reports Server (NTRS)

Oglesby, Donald M. (Inventor); Taylor, Bryant D. (Inventor); Woodard, Stanley E. (Inventor)

2016-01-01

A wireless chemical sensor includes an electrical conductor and a material separated therefrom by an electric insulator. The electrical conductor is an unconnected open-circuit shaped for storage of an electric field and a magnetic field. In the presence of a time-varying magnetic field, the first electrical conductor resonates to generate harmonic electric and magnetic field responses. The material is positioned at a location lying within at least one of the electric and magnetic field responses so-generated. The material changes in electrical conductivity in the presence of a chemical-of-interest.

Wireless Chemical Sensor and Sensing Method for Use Therewith

NASA Technical Reports Server (NTRS)

Woodard, Stanley E. (Inventor); Oglesby, Donald M. (Inventor); Taylor, Bryant Douglas (Inventor)

2014-01-01

A wireless chemical sensor includes an electrical conductor and a material separated therefrom by an electric insulator. The electrical conductor is an unconnected open-circuit shaped for storage of an electric field and a magnetic field. In the presence of a time-varying magnetic field, the first electrical conductor resonates to generate harmonic electric and magnetic field responses. The material is positioned at a location lying within at least one of the electric and magnetic field responses so-generated. The material changes in electrical conductivity in the presence of a chemical-of-interest.

Wireless Chemical Sensing Method

NASA Technical Reports Server (NTRS)

Taylor, Bryant D. (Inventor); Woodard, Stanley E. (Inventor); Oglesby, Donald M. (Inventor)

2017-01-01

A wireless chemical sensor includes an electrical conductor and a material separated therefrom by an electric insulator. The electrical conductor is an unconnected open-circuit shaped for storage of an electric field and a magnetic field. In the presence of a time-varying magnetic field, the first electrical conductor resonates to generate harmonic electric and magnetic field responses. The material is positioned at a location lying within at least one of the electric and magnetic field responses so-generated. The material changes in electrical conductivity in the presence of a chemical-of-interest.

Giant Electric Field Enhancement in Split Ring Resonators Featuring Nanometer-Sized Gaps

NASA Astrophysics Data System (ADS)

Bagiante, S.; Enderli, F.; Fabiańska, J.; Sigg, H.; Feurer, T.

2015-01-01

Today's pulsed THz sources enable us to excite, probe, and coherently control the vibrational or rotational dynamics of organic and inorganic materials on ultrafast time scales. Driven by standard laser sources THz electric field strengths of up to several MVm-1 have been reported and in order to reach even higher electric field strengths the use of dedicated electric field enhancement structures has been proposed. Here, we demonstrate resonant electric field enhancement structures, which concentrate the incident electric field in sub-diffraction size volumes and show an electric field enhancement as high as ~14,000 at 50 GHz. These values have been confirmed through a combination of near-field imaging experiments and electromagnetic simulations.

Long term electromagnetic monitoring at Parkfield, CA

NASA Astrophysics Data System (ADS)

Kappler, Karl Neil

Electric and magnetic fields in the (10-4-1.0) Hz band were monitored at two sites adjacent to the San Andreas Fault near Parkfield and Hollister, California. Observed fields typically comprise natural magnetotelluric fields, with cultural and instrument noise. A data window [2002-2005], enclosing the September 28, 2004 M6 Parkfield earthquake, was analyzed to determine if anomalous electric or magnetic fields, or changes in ground conductivity, occurred before the earthquake. The data were edited, removing intervals of instrument malfunction, leaving 875 days left in the four-year period. Frequent, local spike-like disturbances were removed. The distribution of these spikes was not biased around the time of the earthquake. Signal to noise ratios, estimated via magnetotelluric processing techniques, provided an index of data quality. Plots of signal and noise amplitude spectra, showed the behavior of the ULF fields to be remarkably constant over the period of analysis. From these first-order plots, it is clear that most of the recorded energy is coherent over the spatial extent of the array. Three main statistical techniques were employed to separate local anomalous electrical or magnetic fields from the dominant coherent natural fields: transfer function estimates between components at each site were employed to subtract the dominant field, and look deeper at the 'residual' fields; the data were decomposed into principal components to identify linear combinations of array channels, which are maximally uncorrelated; the technique of canonical coherences was employed to distinguish anomalous fields which are spatially broad from anomalies which occur at a single site only, and furthermore to distinguish anomalies which are present in both the electric and magnetic fields form those which are present in only one field type. Standard remote reference apparent resistivity estimates were generated daily at Parkfield. Most of the variation was observed to be seasonal, and frequency independent, suggesting a local seasonal distortion effect. Once corrected for distortion, nearly all of the variability in the apparent resistivity was removed. In all cases, high levels of sensitivity to subtle electromagnetic effects were demonstrated, but no effects which can be described as precursors to the Parkfield earthquake were found.

Biological and Agricultural Studies on Application of Discharge Plasma and Electromagnetic Fields 5. Effects of High Electric Fields on Animals

NASA Astrophysics Data System (ADS)

Isaka, Katsuo

The biological effects of extremely low frequency electric fields on animals are reviewed with emphasis on studies of the nervous system, behavior, endocrinology, and blood chemistry. First, this paper provides a histrical overview of studies on the electric field effects initiated in Russia and the United States mainly regarding electric utility workers in high voltage substations and transmission lines. Then, the possible mechanisms of electric field effects are explained using the functions of surface electric fields and induced currents in biological objects. The real mechanisms have not yet been identified. The thresholds of electric field perception levels for rats, baboons, and humans are introduced and compared. The experimental results concerning the depression of melatonin secretion in rats exposed to electric fields are described.