WorldWideScience

Sample records for applied electric fields

  1. [Study on dewatering of activated sludge under applied electric field].

    Science.gov (United States)

    Ji, Xue-Yuan; Wang, Yi-Li; Feng, Jing

    2012-12-01

    For an electro-dewatering process of activated sludge (AS), the effect of pH and conductivity of AS, flocculation conditioning and operation factors of horizontal electric field (voltage magnitude, method of applying electric field and distance between plates) were investigated, and the corresponding optimum electro-dewatering conditions were also obtained. The results showed that the best electro-dewatering effect was achieved for AS without change of its pH value (6.93) and conductivity (1.46 mS x cm(-1)). CPAM conditioning could lead to the increase of 30%-40% in the dewatering rate and accelerate the dewatering process, whereas a slight increase in the electro-dewatering rate. The electro-dewatering rate for conditioned AS reached 83.12% during an electric field applied period of 60 minutes, while this rate for original AS could be 75.31% even the electric field applied period extended to 120 minutes. The delay of applying the electric field had an inhibition effect on the AS electro-dewatering rate. Moreover, the optimum conditions for AS electro-dewatering were followed: CPAM dose of 9 g x kg(-1), electric field strength of 600 V x m(-1), distance between the two plates of 40 mm, dehydration time of 60 minutes. Under above optimum conditions the AS electro-dewatering rate could approach to 85.33% and the moisture content in AS decreased from 99.30% to 95.15% accordingly.

  2. Charged Polymers Transport under Applied Electric Fields in Periodic Channels

    Directory of Open Access Journals (Sweden)

    Sorin Nedelcu

    2013-07-01

    Full Text Available By molecular dynamics simulations, we investigated the transport of charged polymers in applied electric fields in confining environments, which were straight cylinders of uniform or non-uniform diameter. In the simulations, the solvent was modeled explicitly and, also, the counterions and coions of added salt. The electrophoretic velocities of charged chains in relation to electrolyte friction, hydrodynamic effects due to the solvent, and surface friction were calculated. We found that the velocities were higher if counterions were moved away from the polymeric domain, which led to a decrease in hydrodynamic friction. The topology of the surface played a key role in retarding the motion of the polyelectrolyte and, even more so, in the presence of transverse electric fields. The present study showed that a possible way of improving separation resolution is by controlling the motion of counterions or electrolyte friction effects.

  3. Effect of applied DC electric fields in flame spread over polyethylene-coated electrical wire

    KAUST Repository

    Jin, Young Kyu

    2011-03-01

    We experimentally investigated the effect of applied DC electric fields on the flame spread over polyethylene-coated electrical wire. The flame-spread rates over electrical wire with negative and positive DC electric fields from 0 to ±7 kV were measured and analyzed. We compared the results for DC electric fields with previous results for AC electric fields. We explored whether or not various flame shapes could be obtained with DC electric fields and the main reason for the flame-spread acceleration, particularly at the end of the electrical wire, for AC electric fields. We found that DC electric fields do not significantly affect the flame-spread rates. However, the flame shape is mildly altered by the ionic wind effect even for DC electric fields. The flame-spread rate is relevant to the flame shape and the slanted direction in spite of the mild impact. A possible explanation for the flame spread is given by a thermal-balance mechanism and fuel-vapor jet. © 2011 The Korean Society of Mechanical Engineers.

  4. Mechanism of Carbon Nanotubes Aligning along Applied Electric Field

    Institute of Scientific and Technical Information of China (English)

    MA Shao-Jie; GUO Wan-Lin

    2008-01-01

    The mechanism of single-walled carbon nanotubes (SWCNTS)aligning in the direction of external electric field is studied by quantum mechanics calculations.The rotational torque on the carbon nanotubes is proportional to the difference between the longitudinal and transverse polarizabilities and varies with the angle of SWCNTs to the external electric field.The longitudinal polarizability increases with second power of length,while the transverse polarizability increases linearly with length.A zigzag SWCNT has larger longitudinal and transverse polarizabilities than an armchair SWCNT with the same diameter and the discrepancy becomes larger for longer tubes.

  5. The Contribution of Electric Force to Sintering Ⅱ.Natures of the Applied Electric Field for Driving lonic Diffusion

    Institute of Scientific and Technical Information of China (English)

    SHIShang-zhao

    1994-01-01

    Through discussion on the acting forces of the applied electric field on the ionic system,it was shown that a periordical field with both even and odd components is to be applied.The suitable wavelengty,the extent of the field intensity and electric potential and the application of the selected field were suggested.

  6. Removal of alum from Iron-Age wooden objects by an applied electric field

    DEFF Research Database (Denmark)

    Christensen, Iben Vernegren; Ottosen, Lisbeth M.; Jensen, Poul;

    2010-01-01

    In this paper removal of potassium, sulfate and aluminum ions from waterlogged alum treated wood with the use of an applied electric field is described. An electric DC field was applied across the wood for 4-20 days. At the end of the experiments sulfate had moved as expected towards the anode...... was not obtained in the experiments reported here, but the high conductivity and the transport of the measured ions due to the electric field indicates that an applied electric field as a method for removal of alum and other unwanted ions from treated wooden objects warrants further investigation....

  7. Crystallization Behavior of Anatase Films in Applied Electric Field Heating Process

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In this research the TiO2 thin films were prepared by sol-gel dip coating. The crystallization of the films in the applied electric field heating process was thoroughly studied by many technique, differential thermal analysis (DTA), Raman spectroscopy and atomic force microscope (AFM). Furthermore the phase formation, microstructure and photo-catalytic activity of TiO2 film were studied under the condition of an electric field heating-treatment. It is found that the existence of applied electric field promotes the phase transformation from anatase to rutile. Studies on photo-catalytic degradation show that the photo-catalytic activity of TiO2 thin films in an applied electric field is higher.

  8. Redistribution of mobile surface charges of an oil droplet in water in applied electric field.

    Science.gov (United States)

    Li, Mengqi; Li, Dongqing

    2016-10-01

    Most researches on oil droplets immersed in aqueous solutions assume that the surface charges of oil droplets are, similar to that of solid particles, immobile and distributed uniformly under external electric field. However, the surface charges at the liquid-liquid interface are mobile and will redistribute under external electric field. This paper studies the redistribution of surface charges on an oil droplet under the influence of the external electrical field. Analytical expressions of the local zeta potential on the surface of an oil droplet after the charge redistribution in a uniform electrical field were derived. The effects of the initial zeta potential, droplet radius and strength of applied electric field on the surface charge redistribution were studied. In analogy to the mobile surface charges, the redistribution of Al2O3-passivated aluminum nanoparticles on the oil droplet surface was observed under applied electrical field. Experimental results showed that these nanoparticles moved and accumulated towards one side of the oil droplet under electric field. The redistribution of the nanoparticles is in qualitative agreement with the redistribution model of the mobile surface charges developed in this work.

  9. The effects of intense laser field and applied electric and magnetic fields on optical properties of an asymmetric quantum well

    Energy Technology Data Exchange (ETDEWEB)

    Restrepo, R.L., E-mail: pfrire@eia.edu.co [Department of Physics, Cumhuriyet University, 58140 Sivas (Turkey); Escuela de Ingeniería de Antioquia-EIA, Envigado (Colombia); Grupo de Materia Condensada-UdeA, Instituto de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia-UdeA, Calle 70 No. 52-21, Medellín (Colombia); Ungan, F.; Kasapoglu, E. [Department of Physics, Cumhuriyet University, 58140 Sivas (Turkey); Mora-Ramos, M.E. [Facultad de Ciencias, Universidad Autonóma del Estado de Morelos, Ave. Universidad 1001, CP 62209, Cuernavaca, Morelos (Mexico); Morales, A.L.; Duque, C.A. [Grupo de Materia Condensada-UdeA, Instituto de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia-UdeA, Calle 70 No. 52-21, Medellín (Colombia)

    2015-01-15

    This paper presents the results of the theoretical study of the effects of non-resonant intense laser field and electric and magnetic fields on the optical properties (the linear and third-order nonlinear refractive index and absorption coefficients) in an asymmetric quantum well. The electric field and intense laser field are applied along the growth direction of the asymmetric quantum well and the magnetic field is oriented perpendicularly. To calculate the energy and the wave functions of the electron in the asymmetric quantum well, the effective mass approximation and the method of envelope wave function are used. The asymmetric quantum well is constructed by using different aluminium concentrations in both right and left barriers. The confinement in the quantum well is changed drastically by either the effect of electric and magnetic fields or by the application of intense laser field. The optical properties are calculated using the compact density matrix approach. The results show that the effect of the intense laser field competes with the effects of the electric and magnetic fields. Consequently, peak position shifts to lower photon energies due to the effect of the intense laser field and it shifts to higher photon energies by the effects of electric and magnetic fields. In general, it is found that the concentration of aluminum, electric and magnetic fields and intense laser field are external agents that modify the optical responses in the asymmetric quantum well.

  10. Finite element modeling and analysis of piezo-integrated composite structures under large applied electric fields

    Science.gov (United States)

    Rao, M. N.; Tarun, S.; Schmidt, R.; Schröder, K.-U.

    2016-05-01

    In this article, we focus on static finite element (FE) simulation of piezoelectric laminated composite plates and shells, considering the nonlinear constitutive behavior of piezoelectric materials under large applied electric fields. Under the assumptions of small strains and large electric fields, the second-order nonlinear constitutive equations are used in the variational principle approach, to develop a nonlinear FE model. Numerical simulations are performed to study the effect of material nonlinearity for piezoelectric bimorph and laminated composite plates as well as cylindrical shells. In comparison to the experimental investigations existing in the literature, the results predicted by the present model agree very well. The importance of the present nonlinear model is highlighted especially in large applied electric fields, and it is shown that the difference between the results simulated by linear and nonlinear constitutive FE models cannot be omitted.

  11. Lack of effect of an externally applied electric field on bacterial adhesion to glass

    NARCIS (Netherlands)

    Poortinga, AT; Busscher, HJ; Bos, R.R.M.

    2001-01-01

    Deposition to glass of Streptococcus salivarius HB-C12 and Staphylococcus epidermidis 3399 in a parallel plate flow chamber in the absence and presence of an externally applied electric field has been studied experimentally. No effect on bacterial adhesion, including initial deposition rates, number

  12. Electronic and Shallow Impurity States in Semiconductor Heterostructures Under an Applied Electric Field

    Institute of Scientific and Technical Information of China (English)

    ZHOU Hai-Yang; GU Shi-Wei; SHI Yao-Ming

    2005-01-01

    With the use of variational method to solve the effective mass equation, we have studied the electronic and shallow impurity states in semiconductor heterostructures under an applied electric field. The electron energy levels are calculated exactly and the impurity binding energies are calculated with the variational approach. It is found that the behaviors of electronic and shallow impurity states in heterostructures under an applied electric field are analogous to that of quantum wells. Our results show that with the increasing strength of electric field, the electron confinement energies increase, and the impurity binding energy increases also when the impurity is on the surface, while the impurity binding energy increases at first, to a peak value, then decreases to a value which is related to the impurity position when the impurity is away from the surface. In the absence of electric field, the result tends to the Levine's ground state energy (-1/4 effective Rydberg) when the impurity is on the surface, and the ground impurity binding energy tends to that in the bulk when the impurity is far away from the surface. The dependence of the impurity binding energy on the impurity position for different electric field is also discussed.

  13. Optical Conductivity of Impurity-Doped Parabolic Quantum Wells in an Applied Electric Field

    Institute of Scientific and Technical Information of China (English)

    GUO Kang-Xian; CHEN Chuan-Yu

    2005-01-01

    The optical conductivity of impurity-doped parabolic quantum wells in an applied electric field is investigated with the memory-function approach, and the analytic expression for the optical conductivity is derived. With characteristic parameters pertaining to GaAs/Ga1-xAlxAs parabolic quantum wells, the numerical results are presented.It is shown that, the smaller the well width, the larger the peak intensity of the optical conductivity, and the more asymmetric the shape of the optical conductivity; the optical conductivity is more sensitive to the electric field, the electric field enhances the optical conductivity; when the dimension of the quantum well increases, the optical conductivity increases until it reaches a maximum value, and then decreases.

  14. Experimental Study on Downwardly Spreading Flame over Inclined Polyethylene-insulated Electrical Wire with Applied AC Electric Fields

    KAUST Repository

    Lim, Seung Jae

    2014-12-30

    An experimental study on downwardly spreading flame over slanted electrical wire, which is insulated by Polyethylene (PE), was conducted with applied AC electric fields. The result showed that the flame spread rate decreased initially with increase in inclination angle of wire and then became nearly constant. The flame shape was modified significantly with applied AC electric field due to the effect of ionic wind. Such a variation in flame spread rate could be explained by a thermal balance mechanism, depending on flame shape and slanted direction of flame. Extinction of the spreading flame was not related to angle of inclination, and was described well by a functional dependency upon the frequency and voltage at extinction.

  15. Extensional flow of nematic liquid crystal with an applied electric field

    KAUST Repository

    CUMMINGS, L. J.

    2013-10-17

    Systematic asymptotic methods are used to formulate a model for the extensional flow of a thin sheet of nematic liquid crystal. With no external body forces applied, the model is found to be equivalent to the so-called Trouton model for Newtonian sheets (and fibres), albeit with a modified \\'Trouton ratio\\'. However, with a symmetry-breaking electric field gradient applied, behaviour deviates from the Newtonian case, and the sheet can undergo finite-time breakup if a suitable destabilizing field is applied. Some simple exact solutions are presented to illustrate the results in certain idealized limits, as well as sample numerical results to the full model equations. Copyright © Cambridge University Press 2013.

  16. Optical nonlinearities associated to applied electric fields in parabolic two-dimensional quantum rings

    Energy Technology Data Exchange (ETDEWEB)

    Duque, C.M., E-mail: cduque@fisica.udea.edu.co [Instituto de Física, Universidad de Antioquia, AA 1226, Medellín (Colombia); Morales, A.L. [Instituto de Física, Universidad de Antioquia, AA 1226, Medellín (Colombia); Mora-Ramos, M.E. [Instituto de Física, Universidad de Antioquia, AA 1226, Medellín (Colombia); Facultad de Ciencias, Universidad Autónoma del Estado de Morelos, Ave. Universidad 1001, CP 62209, Cuernavaca, Morelos (Mexico); Duque, C.A. [Instituto de Física, Universidad de Antioquia, AA 1226, Medellín (Colombia)

    2013-11-15

    The linear and nonlinear optical absorption as well as the linear and nonlinear corrections to the refractive index are calculated in a disc shaped quantum dot under the effect of an external magnetic field and parabolic and inverse square confining potentials. The exact solutions for the two-dimensional motion of the conduction band electrons are used as the basis for a perturbation-theory treatment of the effect of a static applied electric field. In general terms, the variation of one of the different potential energy parameters – for a fixed configuration of the remaining ones – leads to either blueshifts or redshifts of the resonant peaks as well as to distinct rates of change for their amplitudes. -- Highlights: • Optical absorption and corrections to the refractive in quantum dots. • Electric and magnetic field and parabolic and inverse square potentials. • Perturbation-theory treatment of the effect of the electric field. • Induced blueshifts or redshifts of the resonant peaks are studied. • Evolution of rates of change for amplitudes of resonant peaks.

  17. Tuning the energy gap of bilayer α-graphyne by applying strain and electric field

    Science.gov (United States)

    Yang, Hang; Wu, Wen-Zhi; Jin, Yu; Wan-Lin, Guo

    2016-02-01

    Our density functional theory calculations show that the energy gap of bilayer α-graphyne can be modulated by a vertically applied electric field and interlayer strain. Like bilayer graphene, the bilayer α-graphyne has electronic properties that are hardly changed under purely mechanical strain, while an external electric field can open the gap up to 120 meV. It is of special interest that compressive strain can further enlarge the field induced gap up to 160 meV, while tensile strain reduces the gap. We attribute the gap variation to the novel interlayer charge redistribution between bilayer α-graphynes. These findings shed light on the modulation of Dirac cone structures and potential applications of graphyne in mechanical-electric devices. Project supported by the National Key Basic Research Program of China (Grant Nos. 2013CB932604 and 2012CB933403), the National Natural Science Foundation of China (Grant Nos. 51472117 and 51535005), the Research Fund of State Key Laboratory of Mechanics and Control of Mechanical Structures, China (Grant No. 0414K01), the Nanjing University of Aeronautics and Astronautics (NUAA) Fundamental Research Funds, China (Grant No. NP2015203), and the Priority Academic Program Development of Jiangsu Higher Education Institutions.

  18. Transmittance fluctuations and non-linearity in random chains in the presence of applied electric fields

    International Nuclear Information System (INIS)

    We have carried out numerical investigations of transmittance fluctuations in disordered chains in the presence of external electric fields. We have obtained an almost constant fluctuation in a length scale smaller than the localization length. However, the value of the fluctuation in the plateau region is dependent on the external electric field and strength of disorder. We have also studied the transmittance autocorrelation as a function of external electric field to probe non-linearity in transmittance. (author). 26 refs, 4 figs

  19. Electronic structures of stacked layers quantum dots: influence of the non-perfect alignment and the applied electric field

    Institute of Scientific and Technical Information of China (English)

    Jia Bo-Yong; Yu Zhong-Yuan; Liu Yu-Min; Han Li-Hong; Yao Wen-Jie; Feng Hao; Ye Han

    2011-01-01

    Electronic structures of the artificial molecule comprising two truncated pyramidal quantum dots vertically coupled and embedded in the matrix are theoretically analysed via the finite element method. When the quantum dots are completely aligned, the electron energy levels decrease with the horizontally applied electric field. However, energy levels may have the maxima at non-zero electric field if the dots are staggered by a distance of several nanometers in the same direction of the electric field. In addition to shifting the energy levels, the electric field can also manipulate the electron wavefunctions confined in the quantum dots, in company with the non-perfect alignment.

  20. Ionization at a solid-water interface in an applied electric field: Charge regulation

    Science.gov (United States)

    Okamoto, Ryuichi; Onuki, Akira

    2016-09-01

    We investigate ionization at a solid-water interface in an applied electric field. We attach an electrode to a dielectric film bearing silanol or carboxyl groups with an areal density Γ0, where the degree of dissociation α is determined by the proton density in water close to the film. We show how α depends on the density n0 of NaOH in water and the surface charge density σm on the electrode. For σm > 0, the protons are expelled away from the film, leading to an increase in α. In particular, in the range 0 < σm < eΓ0, self-regulation occurs to realize α ≅ σm/eΓ0 for n0 ≪ nc, where nc is 0.01 mol/L for silica surfaces and is 2 × 10-5 mol/L for carboxyl-bearing surfaces. We also examine the charge regulation with decreasing the cell thickness H below the Debye length κ-1, where a crossover occurs at the Gouy-Chapman length. In particular, when σm ˜ eΓ0 and H ≪ κ-1, the surface charges remain only partially screened by ions, leading to a nonvanishing electric field in the interior.

  1. Applied electric field to fabricate colloidal crystals with the photonic band-gap in communication waveband

    Institute of Scientific and Technical Information of China (English)

    Yan Hai-Tao; Wang Ming; Ge Yi-Xian; Yu Ping

    2009-01-01

    The macropore silica colloidal crystal templates were assembled orderly in a capillary glass tube by an applied electric field method to control silica deposition. In order to achieve the photonic band gap (PBG) of colloidal crystal in optical communication waveband, the diameter of silica microspheres is selected by Bragg diffraction formula. An experiment was designed to test the bandgap of the silica crystal templates. This paper discusses the formation process and the close-packed fashion of the silica colloidal crystal templates was discussed. The surface morphology of the templates was also analyzed. The results showed that the close-packed fashion of silica array templates was face-centered cubic (FCC) structure. The agreement is very good between the experimental data and the theoretical calculation.

  2. Carbon nanotubes with atomic impurities on boron nitride sheets under applied electric fields

    OpenAIRE

    Kang, Seoung-Hun; Kim, Gunn; Kwon, Young-Kyun

    2013-01-01

    We perform first-principles calculations to investigate the structural and electronic properties of metal-doped (10, 0) carbon nanotubes (CNTs) on a single hexagonal boron nitride (hBN) sheet in the presence of an external electric field. We consider K, Cl and Ni atoms as dopants to study the dependence of the electronic properties of the CNT on doping polarity and concentration. The electric field strength is varied from -0.2 V/\\AA to +0.2 V/\\AA to explore the effects of an external electric...

  3. The effects of applied electric fields on Micrasterias. I. Morphogenesis and the pattern of cell wall deposition.

    Science.gov (United States)

    Brower, D L; McIntosh, J R

    1980-04-01

    Applied electric fields of approximately 14 V/cm have profound effects on the morphogenesis of the unicellular green alga, Micrasterias denticulata. This field corresponds to a potential drop of 15-40 mV across lobes oriented perpendicular to the applied field. These lobes show a galvanotropism toward the cathode. Lobes growing parallel to the field are stunted to varying degrees, depending on their orientation. As shown by other investigators, most cell wall material is normally deposited at the tips of growing lobes. If, however, cell expansion is osmotically inhibited in electric fields, wall material also accumulates along the cathode-facing (CF) sides of lobes oriented perpendicular to the field. Similarly, in cells growing under the influence of an applied field, radioactively labelled glucose and the methyl groups from methionine are incorporated along the CF sides of lobes as well as the lobe tips. This is also true when the label is added immediately after cells are removed from the fields, indicating that the wall-depositing machinery itself has been temporarily altered by the field. These results demonstrate that applied electric fields can be a valuable tool in elucidating the mechanisms of growth localization in Micrasterias cells. PMID:7400236

  4. Health-Economics Analyses Applied to ELF Electric and Magnetic Fields.

    Science.gov (United States)

    Kandel, Shaiela; Swanson, John; Kheifets, Leeka

    2016-06-01

    Extremely low frequency electric and magnetic fields (ELF EMFs) are a common exposure for modern populations. The prevailing public-health protection paradigm is that quantitative exposure limits are based on the established acute effects, whereas the possible chronic effects are considered too uncertain for quantitative limits, but might justify precautionary measures. The choice of precautionary measures can be informed by a health-economics analysis (HEA). We consider four such analyses of precautionary measures that have been conducted at a national or state level in California, the Netherlands, the United Kingdom, and Israel. We describe the context of each analysis, examine how they deal with some of the more significant issues that arise, and present a comparison of the input parameters and assumptions used. The four HEAs are methodologically similar. The most significant qualitative choices that have to be made are what dose-response relationship to assume, what allowance if any to make for uncertainty, and, for a CBA only, what diseases to consider, and all four analyses made similar choices. These analyses suggest that, on the assumptions made, there are some low-cost measures, such as rephasing, that can be applied to transmission in some circumstances and that can be justifiable in cost-benefit terms, but that higher cost measures, such as undergrounding, become unjustifiable. Of the four HEAs, those in the United Kingdom and Israel were influential in determining the country's EMF policy. In California and Netherlands, the HEA may well have informed the debate, but the policy chosen did not stem directly from the HEA. PMID:26800316

  5. Reactive molecular dynamics of the initial oxidation stages of Ni111 in pure water: effect of an applied electric field.

    Science.gov (United States)

    Assowe, O; Politano, O; Vignal, V; Arnoux, P; Diawara, B; Verners, O; van Duin, A C T

    2012-12-01

    Corrosion processes occurring in aqueous solutions are critically dependent upon the interaction between the metal electrode and the solvent. In this work, the interaction of a nickel substrate with water molecules has been investigated using reactive force field (ReaxFF) molecular dynamics simulations. This approach was originally developed by van Duin and co-workers to study hydrocarbon chemistry and the catalytic properties of organic compounds. To our knowledge, this method has not previously been used to study the corrosion of nickel. In this work, we studied the interaction of 480 molecules of water (ρ = 0.99 g·cm(-3)) with Ni(111) surfaces at 300 K. The results showed that a water "bilayer" was adsorbed on the nickel surface. In the absence of an applied electric field, no dissociation of water was observed. However, the nickel atoms at the surface were charged positively, whereas the first water layer was charged negatively, indicating the formation of an electric double layer. To study the corrosion of nickel in pure water, we introduced an external electric field between the metal and the solution. The electric field intensity varied between 10 and 20 MeV/cm. The presence of this electric field led to oxidation of the metal surface. The structural and morphological differences associated with the growth of this oxide film in the presence of the electric field were evaluated. The simulated atomic trajectories were used to analyze the atomic displacement during the reactive process. The growth of the oxide scale on the nickel surface was primarily due to the movement of anions toward the interior of the metal substrate and the migration of nickel toward the free surface. We found that increasing the electric field intensity sped up the corrosion of nickel. The results also showed that the oxide film thickness increased linearly with increasing electric field intensity.

  6. Lasing characteristics of a pendant drop deformed by an applied electric field.

    Science.gov (United States)

    Pu, X Y; Lee, W K

    2000-04-01

    The lasing properties of an oval-shaped resonant cavity (ORC) with a continuously variable aspect ratio have been studied. The ORC was formed with a dye-doped pendant drop placed inside a variable static electric field. When the drop ORC was pumped by a nitrogen laser, lasing from the ORC was found to have strong directional emission characteristics and an intensity enhancement factor as great as 19.5. Calculated results of light rays escaping from ORC's by refraction are in good agreement with the experimental data. PMID:18064081

  7. Effect of nonlinear absorption on electric field applied lead chloride by Z-scan technique

    Energy Technology Data Exchange (ETDEWEB)

    Rejeena, I. [International School of Photonics, Cochin University of Science and Technology, Cochin Kerala, India and M.S.M. College, Kayamkulam, Kerala (India); Lillibai,; Nampoori, V. P. N.; Radhakrishnan, P. [International School of Photonics, Cochin University of Science and Technology, Cochin Kerala (India); Rahimkutty, M. H. [M.S.M. College, Kayamkulam, Kerala (India)

    2014-10-15

    The preparation, spectral response and optical nonlinearity of gel grown lead chloride single crystals subjected to electric field of 20V using parallel plate arrangements have been investigated. Optical band gap of the samples were determined using linear absorption spectra. Open aperture z-scan was employed for the determination of nonlinear absorption coefficient of PbCl{sub 2} solution. The normalized transmittance curve exhibits a valley shows reverse saturable absorption. The non linear absorption at different input fluences were recorded using a single Gaussian laser beam in tight focus geometry. The RSA nature of the sample makes it suitable for optical limiting applications.

  8. Donor impurity states and related optical response in a lateral coupled dot-ring system under applied electric field

    Energy Technology Data Exchange (ETDEWEB)

    Correa, J.D. [Departamento de Ciencias Básicas, Universidad de Medellín, Medellín (Colombia); Mora-Ramos, M.E. [Centro de Investigación en Ciencias, Instituto de Ciencias Básicas y Aplicadas, Universidad Autonoma del Estado de Morelos, Av. Universidad 1001, CP 62209 Cuernavaca, Morelos (Mexico); Duque, C.A., E-mail: cduque@fisica.udea.edu.co [Grupo de Materia Condensada-UdeA, Instituto de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia)

    2015-09-01

    A study on the effects of an externally applied electric field on the linear optical absorption and relative refractive index change associated with transitions between off-center donor impurity states in laterally coupled quantum dot-ring system is reported. Electron states are calculated within the effective mass and parabolic band approximations by means of an exact diagonalization procedure. The states and the optical response in each case show significant sensitivity to the geometrical distribution of confining energies as well as to the strength of the applied field.

  9. Intense laser effects on nonlinear optical absorption and optical rectification in single quantum wells under applied electric and magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Duque, C.A., E-mail: cduque_echeverri@yahoo.es [Instituto de Fisica, Universidad de Antioquia, AA 1226 Medellin (Colombia); Kasapoglu, E. [Department of Physics, Cumhuriyet University, 58140 Sivas (Turkey); Sakiroglu, S. [Dokuz Eyluel University, Physics Department, 35160 Buca, Izmir (Turkey); Sari, H. [Department of Physics, Cumhuriyet University, 58140 Sivas (Turkey); Soekmen, I. [Dokuz Eyluel University, Physics Department, 35160 Buca, Izmir (Turkey)

    2011-01-01

    In this work the effects of intense laser on the electron-related nonlinear optical absorption and nonlinear optical rectification in GaAs-Ga{sub 1-x}Al{sub x}As quantum wells are studied under, applied electric and magnetic field. The electric field is applied along the growth direction of the quantum well whereas the magnetic field has been considered to be in-plane. The calculations were performed within the density matrix formalism with the use of the effective mass and parabolic band approximations. The intense laser effects are included through the Floquet method, by modifying the confining potential associated to the heterostructure. Results are presented for the nonlinear optical absorption, the nonlinear optical rectification and the resonant peak of these two optical processes. Several configurations of the dimensions of the quantum well, the applied electric and magnetic fields, and the incident intense laser radiation have been considered. The outcome of the calculation suggests that the nonlinear optical absorption and optical rectification are non-monotonic functions of the dimensions of the heterostructure and of the external perturbations considered in this work.

  10. Electron and donor-impurity-related Raman scattering and Raman gain in triangular quantum dots under an applied electric field

    Science.gov (United States)

    Tiutiunnyk, Anton; Akimov, Volodymyr; Tulupenko, Viktor; Mora-Ramos, Miguel E.; Kasapoglu, Esin; Morales, Alvaro L.; Duque, Carlos Alberto

    2016-04-01

    The differential cross-section of electron Raman scattering and the Raman gain are calculated and analysed in the case of prismatic quantum dots with equilateral triangle base shape. The study takes into account their dependencies on the size of the triangle, the influence of externally applied electric field as well as the presence of an ionized donor center located at the triangle's orthocenter. The calculations are made within the effective mass and parabolic band approximations, with a diagonalization scheme being applied to obtain the eigenfunctions and eigenvalues of the x- y Hamiltonian. The incident and secondary (scattered) radiation have been considered linearly-polarized along the y-direction, coinciding with the direction of the applied electric field. For the case with an impurity center, Raman scattering with the intermediate state energy below the initial state one has been found to show maximum differential cross-section more than by an order of magnitude bigger than that resulting from the scheme with lower intermediate state energy. The Raman gain has maximum magnitude around 35 nm dot size and electric field of 40 kV/cm for the case without impurity and at maximum considered values of the input parameters for the case with impurity. Values of Raman gain of the order of up to 104cm-1 are predicted in both cases.

  11. Strain distribution and electronic structures of the InAs/GaAs quantum ring molecule in an applied electric field

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The strain distribution and electronic structures of the InAs/GaAs quantum ring molecule are calculated via the finite element method.In our model,three identical InAs quantum rings are aligned vertically and embedded in the cubic GaAs barrier.Considering the band edge modification induced by the strain,the electronic ground state and the dependence of ground state energy on geometric parameters of the quantum ring molecule are investigated.The change of localization of the wavefunction resulting from the applied electric field along the growth direction is observed.The ground state energy decreases as the electric field intensity increases in a parabolic-like mode.The electric field changes the monotonic dependence of the energy level on the inter-ring distance into a non-monotonic one.However,the electric field has no effect on the relationships between the energy level and other geometric parameters such as the inner radius and outer radius.

  12. The effects of applied electric fields on Micrasterias. II. The distributions of cytoplasmic and plasma membrane components.

    Science.gov (United States)

    Brower, D L; Giddings, T H

    1980-04-01

    The accompanying paper describes the effects of applied electric fields on the morphogenesis and patterns of wall deposition of growing cells of Micrasterias denticulata. This paper details the effects of electric fields (approximately 14 V cm-1) on the subcellular components of Micrasterias, including a description of the plasma membrane of growing semi-cells as visualized by freeze-fracturing. There are no gross cytoplasmic abnormalities or asymmetrics in the distributions of cytoplasmic organelles caused by the fields. In particular, neither the Large Vesicles nor Dark Vesicles are concentrated in the cathode-facing (CF) halves of lobes oriented perpendicular to the fields, where extra deposition of wall material has been shown to occur. In freeze-fracture replicas, there are about twice as many plasma membrane particles near the tips of growing lobes as there are in proximal regions of the lobes. Additionally, rosettes, consisting of 6 membrane particles, are seen predominantly in the distal parts of the lobes, and these rosettes are believed to be important in the synthesis of cell wall microfibrils. The applied fields cause a large asymmetry in the distributions of membrane particles, with larger numbers being found on the CF sides of lobes oriented perpendicular to the fields. We were not able to detect a specific effect on any class of particles. Taken all together, the data support the hypothesis that some of the factors responsible for growth localization in Micrasterias reside in the plasma membrane. PMID:7400237

  13. Divertor experiments in a toroidal plasma, with E x B drift due to an applied radial electric field

    Energy Technology Data Exchange (ETDEWEB)

    Strait, E.J.

    1979-09-01

    It is proposed that the E x B drift arising from an externally applied electric field could be used in a tokamak or other toroidal magnetic plasma confinement device to remove plasma and impurities from the region near the wall and reduce the amount of plasma striking the wall. This could either augment or replace a conventional magnetic field divertor. Among the possible advantages of this scheme are easy external control over the rate of removal of plasma, more rapid removal than the naturally occurring rate in a magnetic divertor, and simplification of construction if the magnetic divertor is eliminated. Results of several related experiments performed in the Wisconsin Levitated Octupole are presented.

  14. A new theoretical formulation of coupling thermo-electric breakdown in LDPE film under dc high applied fields

    Science.gov (United States)

    Boughariou, F.; Chouikhi, S.; Kallel, A.; Belgaroui, E.

    2015-12-01

    In this paper, we present a new theoretical and numerical formulation for the electrical and thermal breakdown phenomena, induced by charge packet dynamics, in low-density polyethylene (LDPE) insulating film under dc high applied field. The theoretical physical formulation is composed by the equations of bipolar charge transport as well as by the thermo-electric coupled equation associated for the first time in modeling to the bipolar transport problem. This coupled equation is resolved by the finite-element numerical model. For the first time, all bipolar transport results are obtained under non-uniform temperature distributions in the sample bulk. The principal original results show the occurring of very sudden abrupt increase in local temperature associated to a very sharp increase in external and conduction current densities appearing during the steady state. The coupling between these electrical and thermal instabilities reflects physically the local coupling between electrical conduction and thermal joule effect. The results of non-uniform temperature distributions induced by non-uniform electrical conduction current are also presented for several times. According to our formulation, the strong injection current is the principal factor of the electrical and thermal breakdown of polymer insulating material. This result is shown in this work. Our formulation is also validated experimentally.

  15. Generalizing the correlated chromophore domain model of reversible photodegradation to include the effects of an applied electric field.

    Science.gov (United States)

    Anderson, Benjamin; Kuzyk, Mark G

    2014-03-01

    All observations of photodegradation and self-healing follow the predictions of the correlated chromophore domain model [Ramini et al., Polym. Chem. 4, 4948 (2013)]. In the present work, we generalize the domain model to describe the effects of an electric field by including induced dipole interactions between molecules in a domain by means of a self-consistent field approach. This electric field correction is added to the statistical mechanical model to calculate the distribution of domains that are central to healing. Also included in the model are the dynamics due to the formation of an irreversibly damaged species, which we propose involves damage to the polymer mediated through energy transfer from a dopant molecule after absorbing a photon. As in previous studies, the model with one-dimensional domains best explains all experimental data of the population as a function of time, temperature, intensity, concentration, and now applied electric field. Though the precise nature of a domain is yet to be determined, the fact that only one-dimensional domain models are consistent with observations suggests that they might be made of correlated dye molecules along polymer chains. Furthermore, the voltage-dependent measurements suggest that the largest polarizability axis of the molecules are oriented perpendicular to the chain. PMID:24730866

  16. Generalizing the correlated chromophore domain model of reversible photodegradation to include the effects of an applied electric field

    CERN Document Server

    Anderson, Benjamin

    2013-01-01

    All observations of photodegradation and self healing follow the predictions of the correlated chromophore domain model. [Ramini et.al. Polym. Chem., 2013, 4, 4948.] In the present work, we generalize the domain model to describe the effects of an electric field by including induced dipole interactions between molecules in a domain by means of a self-consistent field approach. This electric field correction is added to the statistical mechanical model to calculate the distribution of domains that are central to healing. Also included in the model are the dynamics due to the formation of an irreversibly damaged species. As in previous studies, the model with a one-dimensional domain best explains all experimental data of the population as a function of time, temperature, intensity, concentration, and now applied electric field. Though the nature of a domain is yet to be determined, the fact that only one-dimensional domain models are consistent with observations suggests that they might be made of correlated d...

  17. A rapid two-dimensional data collection system for the study of ferroelectric materials under external applied electric fields

    Science.gov (United States)

    Vergentev, Tikhon; Bronwald, Iurii; Chernyshov, Dmitry; Gorfman, Semen; Ryding, Stephanie H. M.; Thompson, Paul; Cernik, Robert J.

    2016-01-01

    Synchrotron X-rays on the Swiss Norwegian Beamline and BM28 (XMaS) at the ESRF have been used to record the diffraction response of the PMN–PT relaxor piezoelectric 67% Pb(Mg1/3Nb2/3)O3–33% PbTiO3 as a function of externally applied electric field. A DC field in the range 0–18 kV cm−1 was applied along the [001] pseudo-cubic direction using a specially designed sample cell for in situ single-crystal diffraction experiments. The cell allowed data to be collected on a Pilatus 2M area detector in a large volume of reciprocal space using transmission geometry. The data showed good agreement with a twinned single-phase monoclinic structure model. The results from the area detector were compared with previous Bragg peak mapping using variable electric fields and a single detector where the structural model was ambiguous. The coverage of a significantly larger section of reciprocal space facilitated by the area detector allowed precise phase analysis. PMID:27738414

  18. Determination of the effective diffusion coefficient of water through cement-based materials when applying an electrical field

    International Nuclear Information System (INIS)

    previously formulated. The formation factor, as well as the effective diffusion coefficient, does not depend on the ionic strength of the material pore solution, this being validated for solutions of different composition encompassing the cement materials pore solution diversity. The formation factor also does not vary when the amplitude of the applied electrical field varies, provided both the test duration and the electrical field amplitude are kept within acceptable boundaries. Finally, the comparison between the values of the effective diffusion coefficient obtained with both the constant field migration test and the natural diffusion techniques, for perfectly conditioned and prepared materials, leads us to invalidate the assumption that the effects of the double electrical layer are negligible. (author)

  19. Combined effects of intense laser field and applied electric field on exciton states in GaAs quantum wells: Transition from the single to double quantum well

    Energy Technology Data Exchange (ETDEWEB)

    Duque, C.A. [Instituto de Fisica, Universidad de Antioquia, Medellin (Colombia); Mora-Ramos, M.E. [Facultad de Ciencias, Universidad Autonoma del Estado de Morelos, Cuernavaca, Morelos (Mexico); Kasapoglu, E.; Sari, H. [Physics Department, Cumhuriyet University, Sivas (Turkey); Soekmen, I. [Physics Department, Dokuz Eyluel University, Izmir (Turkey)

    2012-01-15

    The effects of intense laser radiation on the exciton states in GaAs-Ga{sub 1-x}Al{sub x}As quantum wells are studied with the inclusion of applied dc electric fields oriented along the growth direction of the system. The calculations are made within the effective mass and parabolic band approximations. The intense laser effects have been included along the lines of the Floquet method, modifying the confinement potential associated to the heterostructure. The results for the exciton binding energy, the energy of the exciton-related photoluminescence peak, and the carriers overlap integral are presented for several configurations of the quantum well size, the strength of the applied electric fields, and the incident laser radiation. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Improvement in refractive-index change in LiNbO3:Ce:Cu by applying an external electric field

    Institute of Scientific and Technical Information of China (English)

    Dai Cui-Xia; Liu Li-Ren; Liu De-An; Zhou Yu; Chai Zhi-Fang; Luan Zhu

    2005-01-01

    By jointly solving two-centre material equations with a nonzero external electric field and coupled-wave equations,we have numerically studied the dependence of the non-volatile holographic recording in LiNbO3:Ce:Cu crystals on the external electric field. The dominative photovoltaic effect of the non-volatile holographic recording in doubly doped LiNbO3 crystals is directly verified. And an external electric field that is applied in the positive direction along the c-axis (or a large one in the negative direction of the c-axis) in the recording phase and another one that is applied in the negative direction of the c-axis in the fixing phase are both proved to benefit strong photorefractive performances.Experimental verifications are given with a small electric field applied externally.

  1. Applied electric field and hydrostatic pressure effects on quasistationary states in single and coupled GaAs-(Ga,Al)As quantum wells

    Science.gov (United States)

    Schönhöbel, A. M.; Girón, J. A.; Porras-Montenegro, N.

    2014-04-01

    We have studied the effects of hydrostatic pressure and an uniform electric field on the electron energy levels GaAs-(Ga,Al)As single quantum wells (QWs) and coupled double quantum wells (DQWs) by using the Enderlein's method to solve exactly the Schrodringer equation. Numerical results were obtained using the density of states (DOS) as a function of the applied electric field, hydrostatic pressure, Al concentration, and the geometry as well. We found that the quasistationary ground and excited states energy diminish with and the applied electric field, increase with the confinement potential and the width of central barrier in the DQW. In the latter structure we observed the anti-crossing between the first and second quasistationary energy levels. We found that the applied electric field and the hydrostatic pressure modify the period of Pulsations in QWs.

  2. Effect of Rare Earth Elements (Er, Ho) on Semi-Metallic Materials (ScN) in an Applied Electric Field

    Science.gov (United States)

    Kim, Hyunjung; Park, Yeonjoon; King, Glen C.; Lee, Kunik; Choi, Sang H.

    2012-01-01

    The development of materials and fabrication technology for field-controlled spectrally active optics is essential for applications such as membrane optics, filters for LIDARs, windows for sensors, telescopes, spectroscopes, cameras and flat-panel displays. The dopants of rare earth elements, in a host of optical systems, create a number of absorption and emission band structures and can easily be incorporated into many high quality crystalline and amorphous hosts. In wide band-gap semiconductors like ScN, the existing deep levels can capture or emit the mobile charges, and can be ionized with the loss or capture of the carriers which are the fundamental basis of concept for smart optic materials. The band gap shrinkage or splitting with dopants supports the possibility of this concept. In the present work, a semi-metallic material (ScN) was doped with rare earth elements (Er, Ho) and tested under an applied electric field to characterize spectral and refractive index shifts by either Stark or Zeeman Effect. These effects can be verified using the UV-Vis spectroscopy, the Hall Effect measurement and the ellipsometric spectroscopy. The optical band gaps of ScN doped with Er and doped with Ho were experimentally estimated as 2.33eV and 2.24eV ( 0.2eV) respectively. This is less than that of undoped ScN (2.5 0.2eV). The red-shifted absorption onset is a direct evidence for the decrease of band gap energy (Eg), and the broadening of valence band states is attributable to the doping cases. A decrease in refractive index with an applied field was observed as a small shift in absorption coefficient using a variable angle spectroscopic ellipsometer. In the presence of an electric field, mobile carriers are redistributed within the space charge region (SCR) to produce this electro-refractive effect. The shift in refractive index is also affected by the density and location of deep potential wells within the SCR. In addition, the microstructure change was observed by a TEM

  3. Externally applied electric fields up to 1.6 × 10(5) V/m do not affect the homogeneous nucleation of ice in supercooled water.

    Science.gov (United States)

    Stan, Claudiu A; Tang, Sindy K Y; Bishop, Kyle J M; Whitesides, George M

    2011-02-10

    The freezing of water can initiate at electrically conducting electrodes kept at a high electric potential or at charged electrically insulating surfaces. The microscopic mechanisms of these phenomena are unknown, but they must involve interactions between water molecules and electric fields. This paper investigates the effect of uniform electric fields on the homogeneous nucleation of ice in supercooled water. Electric fields were applied across drops of water immersed in a perfluorinated liquid using a parallel-plate capacitor; the drops traveled in a microchannel and were supercooled until they froze due to the homogeneous nucleation of ice. The distribution of freezing temperatures of drops depended on the rate of nucleation of ice, and the sensitivity of measurements allowed detection of changes by a factor of 1.5 in the rate of nucleation. Sinusoidal alternation of the electric field at frequencies from 3 to 100 kHz prevented free ions present in water from screening the electric field in the bulk of drops. Uniform electric fields in water with amplitudes up to (1.6 ± 0.4) × 10(5) V/m neither enhanced nor suppressed the homogeneous nucleation of ice. Estimations based on thermodynamic models suggest that fields in the range of 10(7)-10(8) V/m might cause an observable increase in the rate of nucleation.

  4. Electric fields and electrical insulation

    DEFF Research Database (Denmark)

    McAllister, Iain Wilson

    2002-01-01

    The adoption of a field-theoretical approach to problems arising in the framework of electrical insulation is discussed with reference to six main topics, which have been addressed over the last 30 years. These include uniform field electrodes, Green's differential equation, electrode surface......, it is amply demonstrated that such an approach can lead to significant progress in many areas of electrical insulation....

  5. Influence of applied electric field on the absorption coefficient and subband distances in asymmetrical AIN/GaN coupled double quantum wells

    Institute of Scientific and Technical Information of China (English)

    Cen Long-Bin; Shen Bo; qin Zhi-Xin; Zhang Guo-Yi

    2009-01-01

    The influence of applied electric fields on the absorption coefficient and subband distances in asymmetrical AlN/GaN coupled double quantum wells (CDQWs) has been investigated by solving Schrodinger and Poisson equations self-consistently. It is found that the absorption coefficient of the intersubband transition (ISBT) between the ground state and the third excited state (1odd -2even) can be equal to zero when the electric fields are applied in asymmetrical A1N/GaN CDQWs,which is related to applied electric fields induced symmetry recovery of these states. Meanwhile,the energy distances between 1odd -2even and 1even - 2even subbands have different relationships from each other with the increase of applied electric fields due to the different polarization-induced potential drops between the lett and the right wells. The results indicate that an electrical-optical modulator operated within the opto-communication wavelength range can be realized in spite of the strong polarization-induced electric fields in asymmetrical AIN/GaN CDQWs.

  6. Excitons in cylindrical GaAs-Ga{sub 1-x}Al{sub x}As quantum dots under applied electric field

    Energy Technology Data Exchange (ETDEWEB)

    Mora-Ramos, M.E. [Facultad de Ciencias, Universidad Autonoma del Estado de Morelos, Av. Universidad 1001, CP 62209, Cuernavaca, Morelos (Mexico); Duque, C.A., E-mail: cduque@fisica.udea.edu.co [Instituto de Fisica, Universidad de Antioquia, AA 1226 Medellin (Colombia)

    2012-06-15

    The exciton binding energy and photoluminescence energy transition in a GaAs-Ga{sub 1-x}Al{sub x}As cylindrical quantum dot are studied with the use of the effective mass approximation and a variational calculation procedure. The influence of these properties on the application of an electric field along the growth direction of the cylinder is particularly considered. It is shown that for zero applied field the binding energy and the photoluminescence energy transition are decreasing functions of the quantum dot radius and height. Given a fixed geometric configuration, both quantities then become decreasing functions of the electric field strength as well.

  7. Intense laser effects on donor impurity in a cylindrical single and vertically coupled quantum dots under combined effects of hydrostatic pressure and applied electric field

    Energy Technology Data Exchange (ETDEWEB)

    Duque, C.A., E-mail: cduque_echeverri@yahoo.es [Instituto de Fisica, Universidad de Antioquia, AA 1226, Medellin (Colombia); Kasapoglu, E. [Department of Physics, Cumhuriyet University, 58140 Sivas (Turkey); Sakiroglu, S. [Dokuz Eyluel University, Physics Department, 35160 Buca, Izmir (Turkey); NanoScience Center, Department of Physics, P.O. Box 35, FI-40014 University of Jyvaeskylae (Finland); Sari, H. [Department of Physics, Cumhuriyet University, 58140 Sivas (Turkey); Soekmen, I. [Dokuz Eyluel University, Physics Department, 35160 Buca, Izmir (Turkey)

    2010-10-01

    Using the effective mass and parabolic band approximations and a variational procedure we have calculated the combined effects of intense laser radiation, hydrostatic pressure, and applied electric field on shallow-donor impurity confined in cylindrical-shaped single and double GaAs-Ga{sub 1-x}Al{sub x}As QD. Several impurity positions and inputs of the heterostructure dimensions, hydrostatic pressure, and applied electric field have been considered. The laser effects have been introduced by a perturbative scheme in which the Coulomb and the barrier potentials are modified to obtain dressed potentials. Our findings suggest that (1) for on-center impurities in single QD the binding energy is a decreasing function of the dressing parameter and for small dot dimensions of the structures (lengths and radius) the binding energy is more sensitive to the dressing parameter, (2) the binding energy is an increasing/decreasing function of the hydrostatic pressure/applied electric field, (3) the effects of the intense laser field and applied electric field on the binding energy are dominant over the hydrostatic pressure effects, (4) in vertically coupled QD the binding energy for donor impurity located in the barrier region is smaller than for impurities in the well regions and can be strongly modified by the laser radiation, and finally (5) in asymmetrical double QD heterostructures the binding energy as a function of the impurity positions follows a similar behavior to the observed for the amplitude of probability of the noncorrelated electron wave function.

  8. Electric Field Imaging Project

    Science.gov (United States)

    Wilcutt, Terrence; Hughitt, Brian; Burke, Eric; Generazio, Edward

    2016-01-01

    NDE historically has focused technology development in propagating wave phenomena with little attention to the field of electrostatics and emanating electric fields. This work is intended to bring electrostatic imaging to the forefront of new inspection technologies, and new technologies in general. The specific goals are to specify the electric potential and electric field including the electric field spatial components emanating from, to, and throughout volumes containing objects or in free space.

  9. Force acting on a dielectric particle in a concentration gradient by ionic concentration polarization under an externally applied DC electric field.

    Science.gov (United States)

    Kang, Kwan Hyoung; Li, Dongqing

    2005-06-15

    There is a concentration-polarization (CP) force acting on a particle submerged in an electrolyte solution with a concentration (conductivity) gradient under an externally applied DC electric field. This force originates from the two mechanisms: (i) gradient of electrohydrodynamic pressure around the particle developed by the Coulombic force acting on induced free charges by the concentration polarization, and (ii) dielectric force due to nonuniform electric field induced by the conductivity gradient. A perturbation analysis is performed for the electric field, the concentration field, and the hydrodynamic field, under the assumptions of creeping flow and small concentration gradient. The leading order component of this force acting on a dielectric spherical particle is obtained by integrating the Maxwell and the hydrodynamic stress tensors. The analytical results are validated by comparing the surface pressure and the skin friction to those of a numerical analysis. The CP force is proportional to square of the applied electric field, effective for electrically neutral particles, and always directs towards the region of higher ionic concentration. The magnitude of the CP force is compared to that of the electrophoretic and the conventional dielectrophoretic forces. PMID:15897097

  10. Electric field analysis

    CERN Document Server

    Chakravorti, Sivaji

    2015-01-01

    This book prepares newcomers to dive into the realm of electric field analysis. The book details why one should perform electric field analysis and what are its practical implications. It emphasizes both the fundamentals and modern computational methods of electric machines. The book covers practical applications of the numerical methods in high voltage equipment, including transmission lines, power transformers, cables, and gas insulated systems.

  11. Microreactors with Electrical Fields

    NARCIS (Netherlands)

    Agiral, Anil; Gardeniers, Han J.G.E.

    2010-01-01

    The use of electric fields in chemistry is considered an important concept of process intensification. The combination of electricity with chemistry becomes particularly valuable at smaller scales, as they are exploited in microreaction technology. Microreactor systems with integrated electrodes pro

  12. Spectral-phase interferometry for direct electric-field reconstruction applied to seeded extreme-ultraviolet free-electron lasers

    CERN Document Server

    Mahieu, Benoît; De Ninno, Giovanni; Dacasa, Hugo; Lozano, Magali; Rousseau, Jean-Philippe; Zeitoun, Philippe; Garzella, David; Merdji, Hamed

    2015-01-01

    We present a setup for complete characterization of femtosecond pulses generated by seeded free-electron lasers (FEL's) in the extreme-ultraviolet spectral region. Two delayed and spectrally shifted replicas are produced and used for spectral phase interferometry for direct electric field reconstruction (SPIDER). We show that it can be achieved by a simple arrangement of the seed laser. Temporal shape and phase obtained in FEL simulations are well retrieved by the SPIDER reconstruction, allowing to foresee the implementation of this diagnostic on existing and future sources. This will be a significant step towards an experimental investigation and control of FEL spectral phase.

  13. Lattice QCD with strong external electric fields

    OpenAIRE

    Yamamoto, Arata

    2012-01-01

    We study particle generation by a strong electric field in lattice QCD. To avoid the sign problem of the Minkowskian electric field, we adopt the "isospin" electric charge. When a strong electric field is applied, the insulating vacuum is broken down and pairs of charged particles are produced by the Schwinger mechanism. The competition against the color confining force is also discussed.

  14. Apparatuses and methods for generating electric fields

    Science.gov (United States)

    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.

  15. Linear and nonlinear optical properties in an asymmetric double quantum well under intense laser field: Effects of applied electric and magnetic fields

    Science.gov (United States)

    Yesilgul, U.; Al, E. B.; Martínez-Orozco, J. C.; Restrepo, R. L.; Mora-Ramos, M. E.; Duque, C. A.; Ungan, F.; Kasapoglu, E.

    2016-08-01

    In the present study, the effects of electric and magnetic fields on the linear and third-order nonlinear optical absorption coefficients and relative change of the refractive index in asymmetric GaAs/GaAlAs double quantum wells under intense laser fields are theoretically investigated. The electric field is oriented along the growth direction of the heterostructure while the magnetic field is taken in-plane. The intense laser field is linear polarization along the growth direction. Our calculations are made using the effective-mass approximation and the compact density-matrix approach. Intense laser effects on the system are investigated with the use of the Floquet method with the consequent change in the confinement potential of heterostructures. Our results show that the increase of the electric and magnetic fields blue-shifts the peak positions of the total absorption coefficient and of the total refractive index while the increase of the intense laser field firstly blue-shifts the peak positions and later results in their red-shifting.

  16. Exciton spectra in GaAs/Ga1-xAlxAs quantum wells in an externally applied electric field

    Science.gov (United States)

    Zhu, Bangfen

    1988-12-01

    A theory on the exciton spectra in quantum wells in the presence of an external electric field is presented. The theory emphasizes the usually ignored aspect, namely, that the different exciton spinor components correspond to different in-plane angular momenta and only a single spinor component contributes to the optical transition, which in conjunction with the hybridization of the heavy and light holes will affect the exciton binding energies and oscillator strengths drastically. Numerical calculations based on the theory explain the contradictory behavior of the h12a peak observed by Collins et al., which is actually the 2p state of the light-hole-conduction-band (LH1-CB1) exciton.

  17. Cryosurgery with pulsed electric fields.

    Directory of Open Access Journals (Sweden)

    Charlotte S Daniels

    Full Text Available This study explores the hypothesis that combining the minimally invasive surgical techniques of cryosurgery and pulsed electric fields will eliminate some of the major disadvantages of these techniques while retaining their advantages. Cryosurgery, tissue ablation by freezing, is a well-established minimally invasive surgical technique. One disadvantage of cryosurgery concerns the mechanism of cell death; cells at high subzero temperature on the outer rim of the frozen lesion can survive. Pulsed electric fields (PEF are another minimally invasive surgical technique in which high strength and very rapid electric pulses are delivered across cells to permeabilize the cell membrane for applications such as gene delivery, electrochemotherapy and irreversible electroporation. The very short time scale of the electric pulses is disadvantageous because it does not facilitate real time control over the procedure. We hypothesize that applying the electric pulses during the cryosurgical procedure in such a way that the electric field vector is parallel to the heat flux vector will have the effect of confining the electric fields to the frozen/cold region of tissue, thereby ablating the cells that survive freezing while facilitating controlled use of the PEF in the cold confined region. A finite element analysis of the electric field and heat conduction equations during simultaneous tissue treatment with cryosurgery and PEF (cryosurgery/PEF was used to study the effect of tissue freezing on electric fields. The study yielded motivating results. Because of decreased electrical conductivity in the frozen/cooled tissue, it experienced temperature induced magnified electric fields in comparison to PEF delivered to the unfrozen tissue control. This suggests that freezing/cooling confines and magnifies the electric fields to those regions; a targeting capability unattainable in traditional PEF. This analysis shows how temperature induced magnified and focused

  18. Effect of electrical field strength applied by PEF processing and storage temperature on the outgrowth of yeasts and moulds naturally present in a fresh fruit smoothie.

    Science.gov (United States)

    Timmermans, R A H; Nederhoff, A L; Nierop Groot, M N; van Boekel, M A J S; Mastwijk, H C

    2016-08-01

    Pulsed electrical field (PEF) technology offers an alternative to thermal pasteurisation of high-acid fruit juices, by extending the shelf life of food products, while retaining its fresh taste and nutritional value. Substantial research has been performed on the effect of electrical field strength on the inactivation kinetics of spoilage and pathogenic micro-organisms and on the outgrowth of spoilage micro-organisms during shelf life. However, studies on the effect of electrical field strength on the inactivation and outgrowth of surviving populations during shelf life are missing. In this study, we assessed the influence of electrical field strength applied by PEF processing and storage temperature on the outgrowth of surviving yeast and mould populations naturally present in fresh fruit smoothie in time. Therefore, an apple-strawberry-banana smoothie was treated in a continuous-flow PEF system (130L/h), using similar inlet and outlet conditions (preheating temperature 41°C, maximum temperature 58°C) to assure that the amount of energy across the different conditions was kept constant. Smoothies treated with variable electrical field strengths (13.5, 17.0, 20.0 and 24.0kV/cm) were compared to smoothies without treatment for outgrowth of yeasts and moulds. Outgrowth of yeasts and moulds stored at 4°C and 7°C was analysed by plating and visual observation and yeast growth was modelled using the modified logistic growth model (Zwietering model). Results showed that the intensity of the electrical field strength had an influence on the degree of inactivation of yeast cells, resulting in a faster outgrowth over time at lower electrical field strength. Outgrowth of moulds over time was not affected by the intensity of the electrical field strength used. Application of PEF introduces a trade-off between type of spoilage: in untreated smoothie yeasts lead to spoilage after 8days when stored at 4 or 7°C, whereas in PEF treated smoothie yeasts were (partly

  19. Dielectrics in electric fields

    CERN Document Server

    Raju, Gorur G

    2003-01-01

    Discover nontraditional applications of dielectric studies in this exceptionally crafted field reference or text for seniors and graduate students in power engineering tracks. This text contains more than 800 display equations and discusses polarization phenomena in dielectrics, the complex dielectric constant in an alternating electric field, dielectric relaxation and interfacial polarization, the measurement of absorption and desorption currents in time domains, and high field conduction phenomena. Dielectrics in Electric Fields is an interdisciplinary reference and text for professionals and students in electrical and electronics, chemical, biochemical, and environmental engineering; physical, surface, and colloid chemistry; materials science; and chemical physics.

  20. Studies on the Second-Order Nonlinear Optical Properties of Parabolic and Semi-parabolic Quantum Wells with Applied Electric Fields

    Institute of Scientific and Technical Information of China (English)

    ZHANG Li; XIE Hong-Jing

    2004-01-01

    Within the framework of compact density matrix approach and iterative procedure, a detailed procedure for the calculation of the second-harmonic generation (SHG)susceptibility tensor is given in the electric-field-biased parabolic and semi-parabolic quantum wells (QWs). The simple analytical formula for the SHG susceptibility in the systems is also deduced. Numerical results on typical AlGaAs/GaAs materials show that, for the same effective width,the SHG susceptibility in semi-parabolic QW is larger than that in parabolic QW due to the self-asymmetry of the semiparabolic QW, and the applied electric field can make the SHG susceptibilities in both systems enhance remarkably.Moreover, the SHG susceptibility is also related to the parabolic confinement frequency and the relaxation rate of the systems.

  1. Electric circuit theory applied electricity and electronics

    CERN Document Server

    Yorke, R

    1981-01-01

    Electric Circuit Theory provides a concise coverage of the framework of electrical engineering. Comprised of six chapters, this book emphasizes the physical process of electrical engineering rather than abstract mathematics. Chapter 1 deals with files, circuits, and parameters, while Chapter 2 covers the natural and forced response of simple circuit. Chapter 3 talks about the sinusoidal steady state, and Chapter 4 discusses the circuit analysis. The fifth chapter tackles frequency response of networks, and the last chapter covers polyphase systems. This book will be of great help to electrical

  2. Appearance of perfect amorphous linear bulk polyethylene under applied electric field and the analysis by radial distribution function and direct tunneling effect.

    Science.gov (United States)

    Zhang, Rong; Bin, Yuezhen; Yang, Wenxiao; Fan, Shaoyan; Matsuo, Masaru

    2014-02-27

    Without melting flow, linear ultrahigh molecular weight polyethylene (UHMWPE) provided X-ray intensity curve from only amorphous halo at 129.0 °C (surface temperature, Ts arisen by Joule heat) lower than the conventionally known melting point 145.5 °C on applying electric field to UHMWPE-nickel-coated carbon fiber (NiCF) composite. Such surprising phenomenon was analyzed by simultaneous measurements of X-ray intensity, electric current, and Ts as a function of time. The calculated radial distribution function revealed the amorphous structure with disordered chain arrangement. The appearance of such amorphous phase was arisen by the phenomenon that the transferring electrons between overlapped adjacent NiCFs by tunneling effect struck together with X-ray photons and some of the transferring electron flown out from the gap to UHMWPE matrix collided against carbon atoms of UHMWPE. The impact by the collision caused disordering chain arrangement in crystal grains. PMID:24479438

  3. Bone growth in electric fields

    International Nuclear Information System (INIS)

    Research performed in several laboratories has shown that artificially induced currents affect bone growth. Studies of various current characteristics produced by implanted electrodes indicate that continuous dc, interrupted dc, and asymmetric ac all increase osteogenesis at the cathode. Stimulation from an externally applied balanced ac field was reported to reduce bone loss from disuse. The purpose of the study being reported here was to examine the influence of a uniform ac electric field on the normal skeletal growth pattern of rats. Juvenile rats received whole body exposure to uniform, vertical 60-Hz electric fields at 100 kV/m for 30 days. There were no marked alterations in the general growth pattern of the exposed animals compared to controls maintained under similar conditions. Bone growth rate, measured by tetracycline labeling, morphology of lumbar vertebrae and tibias and cortical bone area and marrow space area of tibias were not disturbed by exposure to the electric fields. (author)

  4. Transcranial Electric Field Stimulation

    OpenAIRE

    Arfaee, Arash

    2015-01-01

    Nervous stimulation with electric methods not only has a long history in the treatment of many conditions but also in the last two decades has been used increasingly as a powerful functional brain mapping tool alongside other imaging techniques. This technology has been used to record the stimulation-evoked activity of the stimulated location. This research describes work surrounding a novel technique for brain and nervous stimulation using the electric field as the medium; particularly tra...

  5. Revisiting the Corotation Electric Field

    Science.gov (United States)

    Rothwell, P. L.

    2001-05-01

    The rotation of the Earth's dipole magnetic field produces a corotation electric field in the nonrotating frame of reference. A quick calculation implies that this field might arise from the relative motion of an observer in the nonrotating frame and the motion of rotating magnetic field lines. However, upon applying Faraday's Law one finds that total time rate of change of the magnetic field as seen in the nonrotating frame is zero due to the azimuthal symmetry of the dipole. Therefore, classical EM theory(1) predicts a zero corotation electric field in the nonrotating frame for a vacuum. This conundrum has been traditionally treated in the following manner(2,3). 1) Start with a vacuum state with no conductors and plasma present. The transformation between E (the electric field in the nonrotating frame) and E' (the electric field in the rotating frame)implies that in the rotating frame E' is nonzero while E = 0. 2) In the presence of a thin conducting spherical shell (the ionosphere) polarization charges form in the shell due to the magnetic force on the electrons. A polarization electric field Ep is created such that in the idealized case the shell has a uniform electric potential. This Ep has a component along the magnetic field lines outside the shell. 3) Plasma will polarize along B, thus canceling the parallel component of Ep which allows the potential on the shell to be mapped along the magnetic field lines setting E' = 0. From the transformation equation E is now nonzero. This is the electric field required in the nonrotating frame for the plasma to corotate with the dipole. The presence of the corotation electric field is not a local result, but a nonlocal effect that requires the presence of an ionosphere and a conducting plasma. (1) W.K.H. Panofsky and M. Phillips, Classical Electricity and Magnetism, Addison-Wesley, 1956. (2) H. Alfven and C.-G. Falthammar, Cosmical Electrodynamics, 2nd ed., Oxford Press, 1963. (3) E.W.Hones and J.E.Bergeson, J. Geophys

  6. A comparative investigation of an AB- and AA-stacked bilayer graphene sheet under an applied electric field:A density functional theory study

    Institute of Scientific and Technical Information of China (English)

    Wang Tao; Guo Qing; Liu Yan; Sheng Kuang

    2012-01-01

    An AB- and AA-stacked bilayer graphene sheet (BLG) under an electric field is investigated by ab initio calculation.The interlayer distance between the two layers,band structures,and atomic charges of the system are investigated in the presence of different electric fields normal to the BLG.The AB-stacked BLG is able to tune the bandgap into 0.234 eV with the increase of the external electronic field to 1 V/nm,however,the AA-stacked BLG is not sensitive to the external electric field.In both the cases,the spacing between the BLG slightly change in terms of the electric field.The charges in the AB-stacked BLG are increased with the increase of the electric field,which is considered to be the reason that causes the bandgap opening in the AB-stacked BLG.

  7. Hydrogenic impurity binding energy in vertically coupled Ga{sub 1-x}Al{sub x}As quantum-dots under hydrostatic pressure and applied electric field

    Energy Technology Data Exchange (ETDEWEB)

    Duque, C.M. [Instituto de Fisica, Universidad de Antioquia, AA 1226, Medellin (Colombia); Barseghyan, M.G. [Department of Solid State Physics, Yerevan State University, Al. Manookian 1, 0025 Yerevan (Armenia); Duque, C.A., E-mail: cduque@fisica.udea.edu.c [Instituto de Fisica, Universidad de Antioquia, AA 1226, Medellin (Colombia)

    2009-12-15

    This work deals with a theoretical study, using a variational method and the effective mass approximation, of the ground state binding energy of a hydrogenic donor impurity in a vertically coupled multiple quantum dot structure under the effects of hydrostatic pressure and in-growth direction applied electric field. The low dimensional structure consists of three cylindrical shaped GaAs quantum dots coupled by Ga{sub 1-x}Al{sub x}As barriers. For the hydrostatic pressure has been considered the GAMMA-X crossover in the Ga{sub 1-x}Al{sub x}As material. As a general, the results show that: (1) the binding energy as a function of the impurity position has a similar shape to that shown by the electron wave function without the Coulomb interaction, (2) the presence of the electric field changes dramatically the binding energy profile destroying (favoring) the symmetry in the structures, and (3) depending on the impurity position the binding energy can increase or decrease with the hydrostatic pressure mainly due to increases or decreases of the carrier-wave function symmetry by changing the height of the potential barrier.

  8. Bending and turbulent enhancement phenomena of neutral gas flow containing an atmospheric pressure plasma by applying external electric fields measured by schlieren optical method

    Science.gov (United States)

    Yamada, Hiromasa; Yamagishi, Yusuke; Sakakita, Hajime; Tsunoda, Syuichiro; Kasahara, Jiro; Fujiwara, Masanori; Kato, Susumu; Itagaki, Hirotomo; Kim, Jaeho; Kiyama, Satoru; Fujiwara, Yutaka; Ikehara, Yuzuru; Ikehara, Sanae; Nakanishi, Hayao; Shimizu, Nobuyuki

    2016-01-01

    To understand the mechanism of turbulent enhancement phenomena of a neutral gas flow containing plasma ejected from the nozzle of plasma equipment, the schlieren optical method was performed to visualize the neutral gas behavior. It was confirmed that the turbulent starting point became closer to the nozzle exit, as the amplitude of discharge voltage (electric field) increased. To study the effect of electric field on turbulent enhancement, two sets of external electrodes were arranged in parallel, and the gas from the nozzle was allowed to flow between the upper and lower electrodes. It was found that the neutral gas flow was bent, and the bending angle increased as the amplitude of the external electric field increased. The results obtained using a simple model analysis roughly coincide with experimental data. These results indicate that momentum transport from drifted ions induced by the electric field to neutral particles is an important factor that enhances turbulence.

  9. Electric double layer of anisotropic dielectric colloids under electric fields

    Science.gov (United States)

    Han, M.; Wu, H.; Luijten, E.

    2016-07-01

    Anisotropic colloidal particles constitute an important class of building blocks for self-assembly directed by electrical fields. The aggregation of these building blocks is driven by induced dipole moments, which arise from an interplay between dielectric effects and the electric double layer. For particles that are anisotropic in shape, charge distribution, and dielectric properties, calculation of the electric double layer requires coupling of the ionic dynamics to a Poisson solver. We apply recently proposed methods to solve this problem for experimentally employed colloids in static and time-dependent electric fields. This allows us to predict the effects of field strength and frequency on the colloidal properties.

  10. Electron-related nonlinearities in GaAs-Ga{sub 1-x}Al{sub x}As double quantum wells under the effects of intense laser field and applied electric field

    Energy Technology Data Exchange (ETDEWEB)

    Mora-Ramos, M.E. [Facultad de Ciencias, Universidad Autonoma del Estado de Morelos, Ave. Universidad 1001, CP 62209, Cuernavaca, Morelos, Mexico (Mexico); Instituto de Fisica, Universidad de Antioquia, AA 1226 Medellin (Colombia); Duque, C.A., E-mail: cduque_echeverri@yahoo.es [Instituto de Fisica, Universidad de Antioquia, AA 1226 Medellin (Colombia); Kasapoglu, E.; Sari, H. [Cumhuriyet University, Physics Department, 58140 Sivas (Turkey); Soekmen, I. [Dokuz Eyluel University, Physics Department, 35160 Buca, Izmir (Turkey)

    2013-03-15

    The combined effects of intense laser radiation and applied electric fields on the intersubband-related linear and nonlinear optical properties in GaAs-based quantum wells are discussed. It is shown that for asymmetric double quantum well, the increasing laser field intensity causes progressive redshifts in the peak positions of the second and third harmonic coefficients. However, the resonant peaks of the nonlinear optical rectification can suffer a blueshift or a redshift, depending on the laser strengths. The same feature appears in the case of the resonant peaks corresponding to the total coefficients of optical absorption and relative change in the refractive index. - Highlights: Black-Right-Pointing-Pointer Nonlinear optical properties in double quantum wells. Black-Right-Pointing-Pointer Increasing laser field intensity causes redshifts in the peak positions. Black-Right-Pointing-Pointer Resonant peak of second order nonlinearities can be blue-shifted. Black-Right-Pointing-Pointer Relative change in refractive index depends of the applied electric field. Black-Right-Pointing-Pointer The energy position depends of the laser field parameter.

  11. Classical theory of electric and magnetic fields

    CERN Document Server

    Good, Roland H

    1971-01-01

    Classical Theory of Electric and Magnetic Fields is a textbook on the principles of electricity and magnetism. This book discusses mathematical techniques, calculations, with examples of physical reasoning, that are generally applied in theoretical physics. This text reviews the classical theory of electric and magnetic fields, Maxwell's Equations, Lorentz Force, and Faraday's Law of Induction. The book also focuses on electrostatics and the general methods for solving electrostatic problems concerning images, inversion, complex variable, or separation of variables. The text also explains ma

  12. Electric charge in the stochastic electric field

    CERN Document Server

    Simonov, Yu A

    2016-01-01

    The influence of electric stochastic fields on the relativistic charged particles is investigated in the gauge invariant path integral formalism. Using the cumulant expansion one finds the exponential relaxation of the charge Green's function both for spinless and Dirac charges.

  13. Synchrotron-radiation x-ray multiple diffraction applied to the study of electric-field-induced strain in an organic nonlinear optical material

    Science.gov (United States)

    Avanci, L. H.; Cardoso, L. P.; Sasaki, J. M.; Girdwood, S. E.; Roberts, K. J.; Pugh, D.; Sherwood, J. N.

    2000-03-01

    In this work, distortions produced in the unit cell of a MBANP [(-)-2-(α-methylbenzylamino)-5-nitropyridine] nonlinear organic crystal under the influence of an applied electric field, E-->, are investigated by using synchrotron-radiation x-ray multiple diffraction (XRMD). The method is based in the inherent sensitivity of this technique to determine small changes in the crystal lattice, which provide peak position changes in the XRMD pattern (Renninger scan). A typical Renninger scan shows numerous secondary peaks, each one carrying information on one particular direction within the crystal. The (hkl) peak position in the pattern, for a fixed wavelength, is basically a function of the unit cell lattice parameters. Thus small changes in any parameter due to a strain produced by E--> give rise to a corresponding variation in the (hkl) peak position and the observed strain is related to the piezoelectric coefficients. The advantage of this method is the possibility of determining more than one piezoelectric coefficient from a single Renninger scan measurement [L. H. Avanci, L. P. Cardoso, S. E. Girdwood, D. Pugh, J. N. Sherwood, and K. J. Roberts, Phys. Rev. Lett. 81, 5426 (1998)]. The method has been applied to the MBANP (monoclinic, point group 2) crystal and we were able to determine four piezoelectric coefficients: \\|d21\\|=0.2(1)×10-11 CN-1, \\|d22\\|=24.8(3)×10-11 CN-1, \\|d23\\|=1.3(1)×10-11 CN-1, and \\|d25\\|=5.9(1)×10-11 CN-1. The measurements were carried out using the SRS stations 16.3, Daresbury Laboratory, Warrington, UK.

  14. Electric Field Dependence of the Electrical Conductivity of VOx

    Science.gov (United States)

    Garcia, N.

    1985-01-01

    We have observed non-ohmic behavior in the resistivity of VOx for very small electric fields. In an attempt to explain these results several models are considered. We suggest that the sharpening of the transition to the insulating state with applied electric field is due to a reduction of the length of time during which regions of the sample fluctuate into the insulating state.

  15. Effect of intense high-frequency laser field on the linear and nonlinear intersubband optical absorption coefficients and refractive index changes in a parabolic quantum well under the applied electric field

    Energy Technology Data Exchange (ETDEWEB)

    Yesilgul, U., E-mail: uyesilgul@cumhuriyet.edu.tr [Cumhuriyet University, Physics Department, 58140 Sivas (Turkey); Ungan, F. [Cumhuriyet University, Physics Department, 58140 Sivas (Turkey); Sakiroglu, S. [Dokuz Eylül University, Physics Department, 35160 Buca, İzmir (Turkey); Mora-Ramos, M.E. [Facultad de Ciencias Universidad Autonoma del Estado de Morelos, Ave. Universidad 1001, C.P. 62209 Cuernavaca, Morelos (Mexico); Duque, C.A. [Grupo de Materia Condensada-UdeA, Instituto de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia); Kasapoglu, E.; Sarı, H. [Cumhuriyet University, Physics Department, 58140 Sivas (Turkey); Sökmen, I. [Dokuz Eylül University, Physics Department, 35160 Buca, İzmir (Turkey)

    2014-01-15

    The effects of the intense high-frequency laser field on the optical absorption coefficients and the refractive index changes in a GaAs/GaAlAs parabolic quantum well under the applied electric field have been investigated theoretically. The electron energy levels and the envelope wave functions of the parabolic quantum well are calculated within the effective mass approximation. Analytical expressions for optical properties are obtained using the compact density-matrix approach. The numerical results show that the intense high-frequency laser field has a large effect on the optical characteristics of these structures. Also we can observe that the refractive index and absorption coefficient changes are very sensitive to the electric field in large dimension wells. Thus, this result gives a new degree of freedom in the optoelectronic device applications. -- Highlights: • ILF has a large effect on the optical properties of parabolic quantum wells. • The total absorption coefficients increase as the ILF increases. • The RICs increase as the ILF increases.

  16. Nonlinear cell response to strong electric fields

    Science.gov (United States)

    Bardos, D. C.; Thompson, C. J.; Yang, Y. S.; Joyner, K. H.

    2000-07-01

    The response of living cells to externally applied electric fields is of widespread interest. In particular, the intensification of electric fields across cell membranes is believed to be responsible, through membrane rupture and reversible membrane breakdown processes, for certain types of tissue damage in electrical trauma cases which cannot be attributed to Joule heating. Large elongated cells such as skeletal muscle fibres are particularly vulnerable to such damage. Previous theoretical studies of field intensification across cell membranes in such cells have assumed the membrane current to be linear in the applied field (Ohmic membrane conductivity) and were limited to sinusoidal applied fields. In this paper, we investigate a simple model of a long cylindrical cell, corresponding to nerve or skeletal muscle cells. Employing the electroquasistatic approximation, a system of coupled first-order differential equations for the membrane electric field is derived which incorporates arbitrary time dependence in the external field and nonlinear membrane response (non-Ohmic conductivity). The behaviour of this model is investigated for a variety of applied fields in both the linear and highly nonlinear regimes. We find that peak membrane fields predicted by the nonlinear model are approximately twice as intense, for low-frequency electrical trauma conditions, as those of the linear theory.

  17. Magnetic response to applied electrostatic field in external magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Adorno, T.C. [Universidade de Sao Paulo, Instituto de Fisica, Caixa Postal 66318, Sao Paulo, SP (Brazil); University of Florida, Department of Physics, Gainesville, FL (United States); Gitman, D.M. [Universidade de Sao Paulo, Instituto de Fisica, Caixa Postal 66318, Sao Paulo, SP (Brazil); Tomsk State University, Department of Physics, Tomsk (Russian Federation); Shabad, A.E. [P. N. Lebedev Physics Institute, Moscow (Russian Federation)

    2014-04-15

    We show, within QED and other possible nonlinear theories, that a static charge localized in a finite domain of space becomes a magnetic dipole, if it is placed in an external (constant and homogeneous) magnetic field in the vacuum. The magnetic moment is quadratic in the charge, depends on its size and is parallel to the external field, provided the charge distribution is at least cylindrically symmetric. This magneto-electric effect is a nonlinear response of the magnetized vacuum to an applied electrostatic field. Referring to the simple example of a spherically symmetric applied field, the nonlinearly induced current and its magnetic field are found explicitly throughout the space; the pattern of the lines of force is depicted, both inside and outside the charge, which resembles that of a standard solenoid of classical magnetostatics. (orig.)

  18. Magnetic response to applied electrostatic field in external magnetic field

    CERN Document Server

    Adorno, T C; Shabad, A E

    2014-01-01

    We show, within QED and other possible nonlinear theories, that a static charge localized in a finite domain of space becomes a magnetic dipole, if it is placed in an external (constant and homogeneous) magnetic field in the vacuum. The magnetic moment is quadratic in the charge, depends on its size and is parallel to the external field, provided the charge distribution is at least cylindrically symmetric. This magneto-electric effect is a nonlinear response of the magnetized vacuum to an applied electrostatic field. Referring to a simple example of a spherically-symmetric applied field, the nonlinearly induced current and its magnetic field are found explicitly throughout the space, the pattern of lines of force is depicted, both inside and outside the charge, which resembles that of a standard solenoid of classical magnetostatics.

  19. Electropumping of water with rotating electric fields

    DEFF Research Database (Denmark)

    Hansen, Jesper Schmidt; De Luca, Sergio; Todd, Billy;

    2013-01-01

    exploiting the coupling of spin angular momentum to linear streaming momentum. A spatially uniform rotating electric field is applied to water molecules, which couples to their permanent electric dipole moments. The resulting molecular rotational momentum is converted into linear streaming momentum...

  20. Sensing electric fields using single diamond spins

    CERN Document Server

    Dolde, Florian; Doherty, Marcus W; Nöbauer, Tobias; Rempp, Florian; Balasubramanian, Gopalakrishnan; Wolf, Thomas; Reinhard, Friedemann; Hollenberg, Lloyd C L; Jelezko, Fedor; Wrachtrup, Jörg

    2011-01-01

    The ability to sensitively detect charges under ambient conditions would be a fascinating new tool benefitting a wide range of researchers across disciplines. However, most current techniques are limited to low-temperature methods like single-electron transistors (SET), single-electron electrostatic force microscopy and scanning tunnelling microscopy. Here we open up a new quantum metrology technique demonstrating precision electric field measurement using a single nitrogen-vacancy defect centre(NV) spin in diamond. An AC electric field sensitivity reaching ~ 140V/cm/\\surd Hz has been achieved. This corresponds to the electric field produced by a single elementary charge located at a distance of ~ 150 nm from our spin sensor with averaging for one second. By careful analysis of the electronic structure of the defect centre, we show how an applied magnetic field influences the electric field sensing properties. By this we demonstrate that diamond defect centre spins can be switched between electric and magneti...

  1. Electric field gradients in metals

    International Nuclear Information System (INIS)

    A review of the recent works on electric field gradient in metals is given. The main emphasis is put on the temperature dependence of the electric field gradient in nonmagnetic metals. Some methods of investigation of this effect using nuclear probes are described. One of them is nuclear accoustic resonance method. (S.B.)

  2. Electrical integrity of oxides in a radiation field

    Energy Technology Data Exchange (ETDEWEB)

    Zinkle, S.J. [Oak Ridge National Laboratory, TN (United States); Kinoshita, C.

    1996-04-01

    In the absence of an applied electric field, irradiation generally produces a decrease in the permanent (beam-off) electrical conductivity of ceramic insulators. However, in the past 6 years several research groups have reported a phenomenon known as radiation induced electrical degradation (RIED), which produces significant permanent increases in the electrical conductivity of ceramic insulators irradiated with an applied electric field. RIED has been reported to occur at temperatures between 420 and 800 K with applied electric fields as low as 20 V/mm.

  3. Role of two-photon electronic transitions in the formation of active dynamic conductivity in a three-barrier resonance tunneling structure with an applied Dc electric field

    International Nuclear Information System (INIS)

    The theory of active dynamic conductivity in a three-barrier resonance tunneling structure subjected to the combined action of a weak electromagnetic field and a longitudinal dc electric field is developed with regard for the contribution of laser induced one- and two-photon electronic transitions with different frequencies. For this purpose, the full Schroedinger equation is solved in the effective mass approximation and with the use of the model of rectangular potential wells and barriers for an electron. The maximum contribution of two-photon transitions to the formation of the total active dynamic conductivity in laser-induced transitions is shown not to exceed 38%. Geometric configurations of the resonance tunneling structure, for which the laser radiation intensity increases due to laser induced two-photon electronic transitions, are determined

  4. Introducing electric fields

    Science.gov (United States)

    Roche, John

    2016-09-01

    The clear introduction of basic concepts and definitions is crucial for teaching any topic in physics. I have always found it difficult to teach fields. While searching for better explanations I hit on an approach of reading foundational texts and electromagnetic textbooks in ten year lots, ranging from 1840 to the present. By combining this with modern techniques of textual interpretation I attempt to clarify three introductory concepts: how the field is defined; the principle of superposition and the role of the electrostatic field in a circuit.

  5. Electric Field Uniformity of TEPC

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Wei-hua; WANG; Zhi-qiang; LIU; Yi-na; LI; Chun-juan; LUO; Hai-long

    2012-01-01

    <正>As a proportional counter, the problem with tissue-equivalent proportional counter (TEPC) is that near the end of the anode wire the wall of detector is much closer to the anode, the electric field is stronger, and the gas gain is higher than at the center of the anode, namely end effects. In order to optimize the design of TEPC, a gas-flow TEPC (Fig. 1) is designed and constructed to take the research of electric field distribution characteristics.

  6. What Are Electric and Magnetic Fields? (EMF)

    Science.gov (United States)

    ... Experiments Stories Lessons Topics Games Activities Lessons MENU What are Electric and Magnetic Fields? (EMF) Kids Homepage ... electric power is something we take for granted. What are electric and magnetic fields? Electric and magnetic ...

  7. ESTIMATING ELECTRIC FIELDS FROM VECTOR MAGNETOGRAM SEQUENCES

    International Nuclear Information System (INIS)

    Determining the electric field distribution on the Sun's photosphere is essential for quantitative studies of how energy flows from the Sun's photosphere, through the corona, and into the heliosphere. This electric field also provides valuable input for data-driven models of the solar atmosphere and the Sun-Earth system. We show how observed vector magnetogram time series can be used to estimate the photospheric electric field. Our method uses a 'poloidal-toroidal decomposition' (PTD) of the time derivative of the vector magnetic field. These solutions provide an electric field whose curl obeys all three components of Faraday's Law. The PTD solutions are not unique; the gradient of a scalar potential can be added to the PTD electric field without affecting consistency with Faraday's Law. We then present an iterative technique to determine a potential function consistent with ideal MHD evolution; but this field is also not a unique solution to Faraday's Law. Finally, we explore a variational approach that minimizes an energy functional to determine a unique electric field, a generalization of Longcope's 'Minimum Energy Fit'. The PTD technique, the iterative technique, and the variational technique are used to estimate electric fields from a pair of synthetic vector magnetograms taken from an MHD simulation; and these fields are compared with the simulation's known electric fields. The PTD and iteration techniques compare favorably to results from existing velocity inversion techniques. These three techniques are then applied to a pair of vector magnetograms of solar active region NOAA AR8210, to demonstrate the methods with real data. Careful examination of the results from all three methods indicates that evolution of the magnetic vector by itself does not provide enough information to determine the true electric field in the photosphere. Either more information from other measurements, or physical constraints other than those considered here are necessary to find

  8. Inhibition of brain tumor cell proliferation by alternating electric fields

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Hyesun; Oh, Seung-ick; Hong, Sunghoi, E-mail: shong21@korea.ac.kr, E-mail: radioyoon@korea.ac.kr [School of Biosystem and Biomedical Science, Korea University, Seoul 136-703 (Korea, Republic of); Sung, Jiwon; Jeong, Seonghoon; Yoon, Myonggeun, E-mail: shong21@korea.ac.kr, E-mail: radioyoon@korea.ac.kr [Department of Bio-convergence Engineering, Korea University, Seoul 136-703 (Korea, Republic of); Koh, Eui Kwan [Seoul Center, Korea Basic Science Institute, Seoul 136-713 (Korea, Republic of)

    2014-11-17

    This study was designed to investigate the mechanism by which electric fields affect cell function, and to determine the optimal conditions for electric field inhibition of cancer cell proliferation. Low-intensity (<2 V/cm) and intermediate-frequency (100–300 kHz) alternating electric fields were applied to glioblastoma cell lines. These electric fields inhibited cell proliferation by inducing cell cycle arrest and abnormal mitosis due to the malformation of microtubules. These effects were significantly dependent on the intensity and frequency of applied electric fields.

  9. Electric field controlled emulsion phase contactor

    Science.gov (United States)

    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.

  10. Nonlinear optical rectification and optical absorption in GaAs-Ga1-xAlxAs asymmetric double quantum wells: Combined effects of applied electric and magnetic fields and hydrostatic pressure

    International Nuclear Information System (INIS)

    The intersubband electron-related nonlinear optical absorption and nonlinear optical rectification in GaAs-Ga1-xAlxAs asymmetric double quantum wells are studied, under the influence of combined or independent applied electric and magnetic fields as well as hydrostatic pressure. The outcome of the density matrix formalism and the effective mass, and parabolic-band approximations have been considered as main theoretical tools for the description. It is obtained that under particular geometrical conditions, with or without electric and/or magnetic field strength, the optical rectification is null and, simultaneously, in such circumstances the optical absorption has a relative maximum. It is also detected that the influence of the hydrostatic pressure leads to increasing or decreasing behaviors of the nonlinear optical absorption in dependence of the particular regime of pressure values considered, with significant distinction of the cases of opposite electric field orientations. - Highlights: → Maxima of the NOA correspond to zero in the NOR. → Electric fields can couple the double quantum wells. → Hydrostatic pressure can couple the double quantum wells. → NOA can increase/decrease with hydrostatic pressure. → Overlap between wave functions depends on the magnetic field.

  11. Nonlinear optical rectification and optical absorption in GaAs-Ga{sub 1-x}Al{sub x}As asymmetric double quantum wells: Combined effects of applied electric and magnetic fields and hydrostatic pressure

    Energy Technology Data Exchange (ETDEWEB)

    Karabulut, I. [Department of Physics, Selcuk University, Konya 42075 (Turkey); Mora-Ramos, M.E. [Facultad de Ciencias, Universidad Autonoma del Estado de Morelos, Ave. Universidad 1001, CP 62209, Cuernavaca, Morelos (Mexico); Duque, C.A., E-mail: cduque_echeverri@yahoo.e [Instituto de Fisica, Universidad de Antioquia, AA 1226, Medellin (Colombia)

    2011-07-15

    The intersubband electron-related nonlinear optical absorption and nonlinear optical rectification in GaAs-Ga{sub 1-x}Al{sub x}As asymmetric double quantum wells are studied, under the influence of combined or independent applied electric and magnetic fields as well as hydrostatic pressure. The outcome of the density matrix formalism and the effective mass, and parabolic-band approximations have been considered as main theoretical tools for the description. It is obtained that under particular geometrical conditions, with or without electric and/or magnetic field strength, the optical rectification is null and, simultaneously, in such circumstances the optical absorption has a relative maximum. It is also detected that the influence of the hydrostatic pressure leads to increasing or decreasing behaviors of the nonlinear optical absorption in dependence of the particular regime of pressure values considered, with significant distinction of the cases of opposite electric field orientations. - Highlights: {yields} Maxima of the NOA correspond to zero in the NOR. {yields} Electric fields can couple the double quantum wells. {yields} Hydrostatic pressure can couple the double quantum wells. {yields} NOA can increase/decrease with hydrostatic pressure. {yields} Overlap between wave functions depends on the magnetic field.

  12. The effects of the intense laser field on the nonlinear optical properties of a cylindrical Ga{sub 1−x}Al{sub x}As/GaAs quantum dot under applied electric field

    Energy Technology Data Exchange (ETDEWEB)

    Kasapoglu, E., E-mail: ekasap@cumhuriyet.edu.tr [Department of Physics, Cumhuriyet University, 58140 Sivas (Turkey); Duque, C.A. [Grupo de Materia Condensada-UdeA, Instituto de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia); Mora-Ramos, M.E. [Centro de Investigación en Ciencias, Instituto de Ciencias Básicas y Aplicadas, Universidad Autóonoma del Estado de Morelos, Av. Universidad 1001, CP 62209 Cuernavaca, Morelos (Mexico); Sökmen, I. [Department of Physics, Dokuz Eylül University, 35160 Buca, İzmir (Turkey)

    2015-10-01

    In the present work, the effects of the intense laser field on total optical absorption coefficient (the linear and third-order nonlinear) and total refractive index change (the linear and third-order nonlinear) for transitions between different intersubbands in the Ga{sub 1−x}Al{sub x}As/GaAs cylindrical quantum dot under external electric field are investigated. The calculations were performed within the compact density-matrix formalism with the use of the effective mass approximation. The obtained results show that both total absorption coefficient and refractive index change are sensitive to the electric and intense laser fields. By changing the intensities of the electric and laser fields, we can obtain the blue or red shift, without the need for the growth of many different samples. - Highlights: • The effects of the non-resonant intense laser field and electric field on the nonlinear optical properties of cylindrical quantum dot are investigated. • The both total absorption coefficient and refractive index change are sensitive to dot dimensions and the effects of external fields. • By changing the external fields together with dot dimensions a blue or red shift can be obtained.

  13. THOR Electric Field Instrument - EFI

    Science.gov (United States)

    Khotyaintsev, Yuri; Bale, Stuart D.; Bonnell, John W.; Lindqvist, Per-Arne; Phal, Yamuna; Rothkaehl, Hanna; Soucek, Jan; Vaivads, Andris; Åhlen, Lennart

    2016-04-01

    Turbulence Heating ObserveR (THOR) is the first mission ever flown in space dedicated to plasma turbulence. The Electric Field Instrument (EFI) will measure the vector electric field from 0 to 200 kHz. EFI consists of two sets of sensors: Spin-plane Double Probes (EFI-SDP) providing high sensitivity DC electric field in the spacecraft spin plane (2D), and the High-Frequency Antenna (EFI-HFA) providing 3D electric field at frequencies above ~1 kHz. EFI-SDP consists of 4 biased spherical probes extended on 50 m long wire booms, 90 degrees apart in the spin plane, giving a 100 m baseline for each of the two spin-plane electric field components. EFI-HFA consists of 6 x 1.25 m long monopoles, forming 3 dipolar antennas crossed at 90 degrees to each other. In addition to the sensors, EFI contains HFA and SDP pre-amplifiers, as well as bias electronics boards (BEBs) hosted in the man electronics box of the Field and Wave processor (FWP). As THOR spacecraft has a sun-pointing spin axis, EFI-SDP measures the electric field in the plane approximately orthogonal to the sun using long wire booms. The sun-pointing attitude greatly reduces errors due to wake effects and asymmetric photoelectron clouds, enabling the highly accurate in comparison to earlier missions ±0.1 mV/m near-DC electric field measurements. Interferometry using the electric field probes can be used to infer wavelengths and scale sizes at the smallest scales in the plasma. EFI also measures the floating potential of the satellite, which can be used to estimate the plasma density at very high time resolution (up to a few hundred Hz). The sun-pointing attitude greatly reduces changes in the illuminated area, and hence the associated spin-dependent errors. In combination with densities derived from the observed plasma frequency emission line, EFI monitors the plasma density from DC to a few hundred Hz. EFI measurements characterize electric field and density variations associated with kinetic scale plasma

  14. Electric fields and quantum wormholes

    Science.gov (United States)

    Engelhardt, Dalit; Freivogel, Ben; Iqbal, Nabil

    2015-09-01

    Electric fields can thread a classical Einstein-Rosen bridge. Maldacena and Susskind have recently suggested that in a theory of dynamical gravity the entanglement of ordinary perturbative quanta should be viewed as creating a quantum version of an Einstein-Rosen bridge between the particles, or a "quantum wormhole." We demonstrate within low-energy effective field theory that there is a precise sense in which electric fields can also thread such quantum wormholes. We define a nonperturbative "wormhole susceptibility" that measures the ease of passing an electric field through any sort of wormhole. The susceptibility of a quantum wormhole is suppressed by powers of the U (1 ) gauge coupling relative to that for a classical wormhole but can be made numerically equal with a sufficiently large amount of entangled matter.

  15. Electric fields and quantum wormholes

    CERN Document Server

    Engelhardt, Dalit; Iqbal, Nabil

    2015-01-01

    Electric fields can thread a classical Einstein-Rosen bridge. Maldacena and Susskind have recently suggested that in a theory of dynamical gravity the entanglement of ordinary perturbative quanta should be viewed as creating a quantum version of an Einstein-Rosen bridge between the particles, or a "quantum wormhole". We demonstrate within low-energy effective field theory that there is a precise sense in which electric fields can also thread such quantum wormholes. We define a non-perturbative "wormhole susceptibility" that measures the ease of passing an electric field through any sort of wormhole. The susceptibility of a quantum wormhole is suppressed by powers of the U(1) gauge coupling relative to that for a classical wormhole but can be made numerically equal with a sufficiently large amount of entangled matter.

  16. Asymmetric GaAs n-type double δ-doped quantum wells as a source of intersubband-related nonlinear optical response: Effects of an applied electric field

    Energy Technology Data Exchange (ETDEWEB)

    Rodríguez-Magdaleno, K.A.; Martínez-Orozco, J.C.; Rodríguez-Vargas, I. [Unidad Académica de Física, Universidad Autónoma de Zacatecas, Calz. Solidaridad Esq. Paseo a La Bufa S/N. C.P. 98060 Zacatecas (Mexico); Mora-Ramos, M.E. [Facultad de Ciencias, Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, CP 62209 Cuernavaca, Morelos (Mexico); Física Teórica y Aplicada, Escuela de Ingeniería de Antioquia, AA 7516 Medellín (Colombia); Grupo de Materia Condensada-UdeA, Instituto de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia); Duque, C.A., E-mail: cduque@fisica.udea.edu.co [Grupo de Materia Condensada-UdeA, Instituto de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia)

    2014-03-15

    In this work, the conduction band electron states and the associated intersubband-related linear and nonlinear optical absorption coefficient and relative refractive index change are calculated for an asymmetric double n-type δ-doped quantum well in a GaAs-matrix. The effects of an external applied static electric field are included. Values of the two-dimensional impurities density (N{sub 2d}) of each single δ-doped quantum well are taken to vary within the range of 1.0×10{sup 12} to 7.0×10{sup 12} cm{sup −2}, consistent with the experimental data growth regime. The optical responses are reported as a function of the δ-doped impurities density and the applied electric field. It is shown that single electron states and the related optical quantities are significantly affected by the structural asymmetry of the double δ-doped quantum well system. In addition, a brief comparison with the free-carrier-related optical response is presented. -- Highlights: • Nonlinear optics in asymmetric double n-type δ-doped quantum well in a GaAs-matrix. • The system is considered under external applied electric field in growth direction. • The 2D impurity density is consistent with the experimental data growth regime. • The optical quantities are significantly affected by the structural asymmetry of the system.

  17. Electric field effects in RUS measurements.

    Science.gov (United States)

    Darling, Timothy W; Allured, Bradley; Tencate, James A; Carpenter, Michael A

    2010-02-01

    Much of the power of the Resonant Ultrasound Spectroscopy (RUS) technique is the ability to make mechanical resonance measurements while the environment of the sample is changed. Temperature and magnetic field are important examples. Due to the common use of piezoelectric transducers near the sample, applied electric fields introduce complications, but many materials have technologically interesting responses to applied static and RF electric fields. Non-contact optical, buffered, or shielded transducers permit the application of charge and externally applied electric fields while making RUS measurements. For conducting samples, in vacuum, charging produces a small negative pressure in the volume of the material--a state rarely explored. At very high charges we influence the electron density near the surface so the propagation of surface waves and their resonances may give us a handle on the relationship of electron density to bond strength and elasticity. Our preliminary results indicate a charge sign dependent effect, but we are studying a number of possible other effects induced by charging. In dielectric materials, external electric fields influence the strain response, particularly in ferroelectrics. Experiments to study this connection at phase transformations are planned. The fact that many geological samples contain single crystal quartz suggests a possible use of the piezoelectric response to drive vibrations using applied RF fields. In polycrystals, averaging of strains in randomly oriented crystals implies using the "statistical residual" strain as the drive. The ability to excite vibrations in quartzite polycrystals and arenites is explored. We present results of experimental and theoretical approaches to electric field effects using RUS methods. PMID:19850314

  18. Electric Field Effects in RUS Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Darling, Timothy W [Los Alamos National Laboratory; Ten Cate, James A [Los Alamos National Laboratory; Allured, Bradley [UNIV NEVADA, RENO; Carpenter, Michael A [CAMBRIDGE UNIV. UK

    2009-09-21

    Much of the power of the Resonant Ultrasound Spectroscopy (RUS) technique is the ability to make mechanical resonance measurements while the environment of the sample is changed. Temperature and magnetic field are important examples. Due to the common use of piezoelectric transducers near the sample, applied electric fields introduce complications, but many materials have technologically interesting responses to applied static and RF electric fields. Non-contact optical, buffered, or shielded transducers permit the application of charge and externally applied electric fields while making RUS measurements. For conducting samples, in vacuum, charging produces a small negative pressure in the volume of the material - a state rarely explored. At very high charges we influence the electron density near the surface so the propagation of surface waves and their resonances may give us a handle on the relationship of electron density to bond strength and elasticity. Our preliminary results indicate a charge sign dependent effect, but we are studying a number of possible other effects induced by charging. In dielectric materials, external electric fields influence the strain response, particularly in ferroelectrics. Experiments to study this connection at phase transformations are planned. The fact that many geological samples contain single crystal quartz suggests a possible use of the piezoelectric response to drive vibrations using applied RF fields. In polycrystals, averaging of strains in randomly oriented crystals implies using the 'statistical residual' strain as the drive. The ability to excite vibrations in quartzite polycrystals and arenites is explored. We present results of experimental and theoretical approaches to electric field effects using RUS methods.

  19. Fano resonance and flux-dependent transport through a triple-arm Aharonov-Bohm interferometer under an applied electric field

    International Nuclear Information System (INIS)

    The electron transport through a triple-arm Aharonov-Bohm (TAAB) interferometer with an electron-electron interaction quantum dot embedded in each arm is studied using the Green's function technique by means of self-consistent calculation. Transport through one arm of the TAAB interferometer provides the 'background channel'. Linear conductance shows a symmetric structure including the effect of the Coulomb blockade, even in the out-of-equilibrium state, by applying a finite voltage across the device. Four Fano resonant peaks appear with an opposite Fano factor in the conductance, which is different from that of the double-quantum-dot AB interferometer. Not only the magnitude but also the sign of the Fano factor can be controlled more easily when the energy levels of the quantum dots in the reference arm are modified by adjusting the gate or the bias voltage in experiments. As a function of the magnetic field, the AB oscillation is also affected considerably

  20. Linear electric field mass spectrometry

    Science.gov (United States)

    McComas, David J.; Nordholt, Jane E.

    1992-01-01

    A mass spectrometer and methods for mass spectrometry. The apparatus is compact and of low weight and has a low power requirement, making it suitable for use on a space satellite and as a portable detector for the presence of substances. High mass resolution measurements are made by timing ions moving through a gridless cylindrically symmetric linear electric field.

  1. Linear electric field mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    McComas, D.J.; Nordholt, J.E.

    1991-03-29

    A mass spectrometer is described having a low weight and low power requirement, for use in space. It can be used to analyze the ionized particles in the region of the spacecraft on which it is mounted. High mass resolution measurements are made by timing ions moving through a gridless cylindrically sysmetric linear electric field.

  2. Electrical engineering is an applied mathematics

    Science.gov (United States)

    Zainal, Yuda Bakti; Sambasri, Susanto; Widodo, Rohani Jahja

    2015-05-01

    This paper presents developments and applications of Electrical Engieering (EE) as an Applied Mathematic (AM). Several characteristics of EE can be linked to human behavior. EE can "think" in the sense that they can replace to some extent, human operation. It is a concept or principle that seems to fundamental in nature and not necessarily peculiar to engineering. EE theory can be discussed from four viewpoints as: an intellectual discipline within science and the philosophy of science, a part of engineering, with industrial applications and Social Systems (SS) of the present and the future. In global communication, developed countries and developing countries should build several attractive and sound symbiosis bridges, to prevent loss of universe balances. EE applications have social impacts not only in developed countries but also in developing countries.

  3. Special Effect of Parallel Inductive Electric Field

    Institute of Scientific and Technical Information of China (English)

    陈涛; 刘振兴; W.Heikkila

    2002-01-01

    Acceleration of electrons by a field-aligned electric field during a magnetospheric substorm in the deep geomagnetic tail is studied by means of a one-dimensional electromagnetic particle code. It was found that the free acceleration of the electrons by the parallel electric field is obvious; kinetic energy variation is greater than electromagnetic energy variation in the presence of parallel electric field. Magnetic energy is greater than kinetic energy variation and electric energy variation in the absence of the parallel electric field. More wave modes in the presence of the parallel electric field are generated than those in the absence of the parallel electric field.

  4. Magnetic phase diagram of graphene nanorings in an electric field

    International Nuclear Information System (INIS)

    Magnetic properties of graphene nanorings are investigated in the presence of an electric field. Within the formalism of Hubbard model, the graphene nanorings of various geometric configurations are found to exhibit rich phase diagram. For a nanoring system which has degenerate states at the Fermi level, the system is shown to undergo an abrupt phase transition from the antiferromagnetic to a nonmagnetic state in an electric field applied cross its zigzag edges. However, the nanoring is found to always stay in the antiferromagnetic state when the electric field is applied cross its armchair edges. For the other nanoring system with a finite single-particle gap, the magnetic moments of its antiferromagnetic ground state is seen to decrease gradually to zero with the electric field applied cross the zigzag edges. When the electric field is applied cross the armchair edges, the nanoring is shown to undergo several magnetic phase transitions before settling itself in a nonmagnetic ordering. (paper)

  5. Effect of Electric Field on Conductivity and Vickers Hardness of an A1-Li Alloy

    Institute of Scientific and Technical Information of China (English)

    刘兵; 陈大融; 陈铮; 王永欣; 李晓玲

    2003-01-01

    Static electric fields were applied on an aluminium-lithium alloy during solution treatment.The conductivity and Vickers hardness of the quenched Al-Li alloy is changed with the effect of electric field.The Vickers hardness increases with the applied electric field for a certain solutionizing time but decreases with the time under an electric field.In the absence of the electric field,the Vickers hardness and the conductivity increase synchronously,while reversed after electric field treatment.Positive and negative electric fields had the similar effect.The change of the local electron density in alloy caused by electric field is presented to explain the effect.

  6. Conically shaped drops in electric fields

    Science.gov (United States)

    Stone, Howard A.; Brenner, Michael P.; Lister, John R.

    1996-11-01

    When an electric field is applied to a dielectric liquid containing a suspended immiscible fluid drop, the drop deforms into a prolate ellipsoidal shape. Above a critical field strength the drop develops conical ends, as first observed by Zeleny [Phys. Rev. 10, 1 (1917)] and Wilson & Taylor [Proc. Camb. Phil. Soc. 22, 728 (1925)] for, respectively, the case of conducting drops and soap films in air. The case of two dielectric liquids was studied recently using a slender drop approximation by Li, Halsey & Lobkovsky [Europhys. Lett 27, 575 (1994)]. In this presentation we further develop the slender body approximation to obtain coupled ordinary differential equations for the electric field and the drop shape. Analytical formulae are derived which approximately give the cone angle as a function of the dielectric constant ratio between the two fluids, and the minimum applied electric field at which conical tips first form as a function of the dielectric constant ratio. Finally, drops shapes are calculated numerically and compared with the common prolate shape assumption.

  7. GROUNDWATER AND SOIL REMEDIATION USING ELECTRICAL FIELD

    Science.gov (United States)

    Enhancements of contaminants removal and degradation in low permeability soils by electrical fields are achieved by the processes of electrical heating, electrokinetics, and electrochemical reactions. Electrical heating increases soil temperature resulting in the increase of cont...

  8. Atomistic modeling of metal surfaces under electric fields: direct coupling of electric fields to a molecular dynamics algorithm

    CERN Document Server

    Djurabekova, Flyura; Pohjonen, Aarne; Nordlund, Kai

    2011-01-01

    The effect of electric fields on metal surfaces is fairly well studied, resulting in numerous analytical models developed to understand the mechanisms of ionization of surface atoms observed at very high electric fields, as well as the general behavior of a metal surface in this condition. However, the derivation of analytical models does not include explicitly the structural properties of metals, missing the link between the instantaneous effects owing to the applied field and the consequent response observed in the metal surface as a result of an extended application of an electric field. In the present work, we have developed a concurrent electrodynamic–molecular dynamic model for the dynamical simulation of an electric-field effect and subsequent modification of a metal surface in the framework of an atomistic molecular dynamics (MD) approach. The partial charge induced on the surface atoms by the electric field is assessed by applying the classical Gauss law. The electric forces acting on the partially...

  9. Solving the electrical control of magnetic coercive field paradox

    OpenAIRE

    Vopson, Melvin; Lepadatu, S.

    2014-01-01

    The ability to tune magnetic properties of solids via electric voltages instead of external magnetic fields is a physics curiosity of great scientific and technological importance. Today, there is strong published experimental evidence of electrical control of magnetic coercive fields in composite multiferroic solids. Unfortunately, the literature indicates highly contradictory results. In some studies, an applied voltage increases the magnetic coercive field and in other studies the applied ...

  10. Simultaneous effects of hydrostatic pressure and applied electric field on the impurity-related self-polarization in GaAs/Ga{sub 1-x}Al{sub x}As multiple quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Restrepo, R.L.; Miranda, Guillermo L. [Fisica Teorica y Aplicada, Escuela de Ingenieria de Antioquia, A.A. 7516 Medellin (Colombia); Duque, C.A., E-mail: cduque_echeverri@yahoo.e [Instituto de Fisica, Universidad de Antioquia, A.A. 1226 Medellin (Colombia); Mora-Ramos, M.E. [Facultad de Ciencias, Universidad Autonoma del Estado de Morelos, Av. Universidad 1001, CP 62209 Cuernavaca, Morelos (Mexico)

    2011-05-15

    A detailed theoretical study of the combined effects of hydrostatic pressure and in-growth direction applied electric field on the binding energy and self-polarization of a donor impurity in a system of GaAs-(Ga,Al)As coupled square quantum wells is presented. The study is performed in the framework of the effective mass and parabolic band approximations and using a variational procedure. The electron effective mass, the dielectric constant, the barrier height, the well sizes, all them varying with the hydrostatic pressure are taken into account within the study. The results obtained show that the impurity binding energy and its self-polarization bear strong dependencies with the hydrostatic pressure, the strength of the applied electric field, the width of the confining potential barriers, and the impurity position. - Research highlights: {yields} Impurity binding energy and self-polarization have a conjugate behavior in MQWs. {yields} Binding energy (self-polarization) is an increasing (decreasing) function of HP. {yields} For on-center impurity, the binding energy decreases with EF. {yields} For on-center impurity the self-polarization increases with EF.

  11. Electric field distribution of electron emitter surfaces

    Science.gov (United States)

    Tagawa, M.; Takenobu, S.; Ohmae, N.; Umeno, M.

    1987-03-01

    The electric field distribution of a tungsten field emitter surface and a LaB6 thermionic emitter surface has been studied. The computer simulation of electric field distribution on the emitter surface was carried out with a charge simulation method. The electric field distribution of the LaB6 thermionic emitter was experimentally evaluated by the Schottky plot. Two independent equations are necessary for obtaining local electric field and work function; the Fowler-Nordheim equation and the equation of total energy distribution of emitted electron being used to evaluate the electric field distribution of the tungsten field emitter. The experimental results agreed with the computer simulation.

  12. Electric Field Effect in Intrinsic Josephson Junctions

    Science.gov (United States)

    Koyama, T.

    The electric field effect in intrinsic Josephson junction stacks (IJJ's) is investigated on the basis of the capacitively-coupled IJJ model. We clarify the current-voltage characteristics of the IJJ's in the presence of an external electric field. It is predicted that the IJJ's show a dynamical transition to the voltage state as the external electric field is increased.

  13. Cell separation using electric fields

    Science.gov (United States)

    Mangano, Joseph (Inventor); Eppich, Henry (Inventor)

    2009-01-01

    The present invention involves methods and devices which enable discrete objects having a conducting inner core, surrounded by a dielectric membrane to be selectively inactivated by electric fields via irreversible breakdown of their dielectric membrane. One important application of the invention is in the selection, purification, and/or purging of desired or undesired biological cells from cell suspensions. According to the invention, electric fields can be utilized to selectively inactivate and render non-viable particular subpopulations of cells in a suspension, while not adversely affecting other desired subpopulations. According to the inventive methods, the cells can be selected on the basis of intrinsic or induced differences in a characteristic electroporation threshold, which can depend, for example, on a difference in cell size and/or critical dielectric membrane breakdown voltage. The invention enables effective cell separation without the need to employ undesirable exogenous agents, such as toxins or antibodies. The inventive method also enables relatively rapid cell separation involving a relatively low degree of trauma or modification to the selected, desired cells. The inventive method has a variety of potential applications in clinical medicine, research, etc., with two of the more important foreseeable applications being stem cell enrichment/isolation, and cancer cell purging.

  14. Dielectrophoretic manipulation of macromolecules: The electric field

    International Nuclear Information System (INIS)

    The use of dielectrophoresis is fast becoming a proven technique for manipulating particles and macromolecules in microfluidic systems. Here an analytic solution for the gradient in the electric field strength, {nable}·(E·E), produced by a two-dimensional array of parallel electodes is derived using the method of Green's functions. The boundary condition for the potential between electrodes is estimated by using a linear approximation. While the Green's function used here is somewhat different from Wang , J. Phys. D 29, 1649 (1996), the resulting analytic expression for the potential field is in exact agreement with their result. Selected results for equispaced electrodes with equal widths are compared with Wang , J. Phys. D 29, 1649 (1996). The analytic solution is employed to study the effects of electrode spacing and electrode width on the gradient in electric field intensity. Results show that the magnitude in the gradient in the electric field intensity exhibited the expected dependence on the applied voltage; however, the dependence on electrode width was found to be on the order of the electrode width squared. Results to explore the effects of electrode spacing show that as the spacing is reduced below two electrode widths the magnitude of the gradient increases exponentially

  15. Laser ablation of titanium in liquid in external electric field

    Energy Technology Data Exchange (ETDEWEB)

    Serkov, A.A. [Wave Research Center of A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation); The Federal State Educational Institution of Higher Professional Education, “Moscow Institute of Physics and Technology (State University)”, 9 Institutskiy per., 141700, Dolgoprudny, Moscow Region (Russian Federation); Barmina, E.V., E-mail: barminaev@gmail.com [Wave Research Center of A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation); Shafeev, G.A. [Wave Research Center of A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation); National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), 31, Kashirskoye Highway, 115409 Moscow (Russian Federation); Voronov, V.V. [A.M. Prokhorov General Physics Institute of the Russian Academy of Sciences, 38, Vavilov Street, 119991 Moscow (Russian Federation)

    2015-09-01

    Highlights: • Ablation of a bulk Ti target by 10 ps laser pulses in liquid is experimentally studied in external DC electric field. • Applied cathodic bias leads to increase in average size of self-organized nanostructures formed upon ablation of titanium target. • Laser ablation of Ti target in external electric field results in generation of elongated titanium oxide nanoparticles. - Abstract: Ablation of a bulk Ti target by 10 ps laser pulses in water is experimentally studied in external DC electric field. It is demonstrated that both lateral size of nanostructures (NS) on Ti surface and their density depend on the electric field applied to the target. Scanning Electron Microscopy of NS reveals the shift of their size distribution function toward larger sizes with applied field (cathodic bias, 25 V DC). Density of mushroom-like NS with applied electric field amounts to 10{sup 10} cm{sup −2}. X-ray diffraction of generated nanoparticles (NPs) shows difference in the crystallographic structure of NPs of non-stoichiometric Ti oxides generated with and without electric field. This conclusion is corroborated with the optical absorption spectroscopy of obtained colloids. Transmission Electron Microscopy of NPs also shows difference in morphology of particles produced with and without cathodic bias. The results are interpreted on the basis of instability of the melt on Ti surface in the electric field.

  16. Technique applied in electrical power distribution for Satellite Launch Vehicle

    Directory of Open Access Journals (Sweden)

    João Maurício Rosário

    2010-09-01

    Full Text Available The Satellite Launch Vehicle electrical network, which is currently being developed in Brazil, is sub-divided for analysis in the following parts: Service Electrical Network, Controlling Electrical Network, Safety Electrical Network and Telemetry Electrical Network. During the pre-launching and launching phases, these electrical networks are associated electrically and mechanically to the structure of the vehicle. In order to succeed in the integration of these electrical networks it is necessary to employ techniques of electrical power distribution, which are proper to Launch Vehicle systems. This work presents the most important techniques to be considered in the characterization of the electrical power supply applied to Launch Vehicle systems. Such techniques are primarily designed to allow the electrical networks, when submitted to the single-phase fault to ground, to be able of keeping the power supply to the loads.

  17. Preseismic electric field "strange attractor" like precursor analysis applied on large (Ms > 5.5R) EQs, which occurred in Greece during December 1st, 2007 - April 30th, 2008

    CERN Document Server

    Thanassoulas, C; Verveniotis, G; Zymaris, N

    2008-01-01

    In order to investigate the capability of the preseismic electric field "strange attractor like" precursor as a time predictor of a large EQ within a short time window (short-term prediction), the specific methodology was applied on the Earth's electric field recorded during a rather long seismically active period (December 1st, 2007 - April 30th, 2008) of Greece. During this period of time a number (8) of large (Ms > 5.5R) earthquakes took place. The particular analysis is presented in detail for the following EQs: the Monemvasia EQ (January 6th 2008, Ms = 6.6R), the Methoni EQs (February 14th 2008 Ms = 6.7R, February 19th 2008 Ms = 5.6R, February 20th 2008 Ms = 6.5R, February 26th 2008 Ms = 5.7R), the Skyros EQ (March 19th 2008 Ms = 5.5R) and the Mid Southern Creta EQ (March 28th 2008 Ms = 5.6R). The obtained results from the analysis of the afore mentioned EQs, in conjunction to the ones obtained from an earlier presentation of the particular methodology (Thanassoulas et al. 2008a), suggest: an average tim...

  18. Geostatistical methods applied to field model residuals

    DEFF Research Database (Denmark)

    Maule, Fox; Mosegaard, K.; Olsen, Nils

    The geomagnetic field varies on a variety of time- and length scales, which are only rudimentary considered in most present field models. The part of the observed field that can not be explained by a given model, the model residuals, is often considered as an estimate of the data uncertainty (which...... consists of measurement errors and unmodelled signal), and is typically assumed to be uncorrelated and Gaussian distributed. We have applied geostatistical methods to analyse the residuals of the Oersted(09d/04) field model [http://www.dsri.dk/Oersted/Field_models/IGRF_2005_candidates/], which is based...... on 5 years of Ørsted and CHAMP data, and includes secular variation and acceleration, as well as low-degree external (magnetospheric) and induced fields. The analysis is done in order to find the statistical behaviour of the space-time structure of the residuals, as a proxy for the data covariances...

  19. Effect of applied electric field on slag erosion resistance of Al2 O3-C refractory%外加电场对Al2O3-C耐火材料抗渣侵蚀性能的影响

    Institute of Scientific and Technical Information of China (English)

    孙勇; 马北越; 孙朔; 于景坤; 王臻明

    2009-01-01

    By using different particle size of fused white corundum (147 μm), flake graphite, solid resin, commercial alcohol, zirconia (calcium oxide as stabilizer) as the raw materials, Al2O3-C samples with the length of 850 mm, inner (alumina-graphite) diameter of 50 mm and outer (zirconium) diameter of 85 mm were prepared by cold isostatic compaction pressed at 160 MPa after prilling in granulator. An electric field was applied to Al2O3-C refractory and the effect of current intensity (0.5 A, 1 A and 5 A) on slag erosion resistance was investigated in this paper. The results show that with the increasing of current intensity, the thickness of build-up in cathode increases significantly. CaO·6Al2O3, a high melting point compound generated on the surface of slag line, decreases the slag erosion rate of Al2O3-C refractory dramatically.

  20. Calculation of electric fields in imperfect dielectrics

    Energy Technology Data Exchange (ETDEWEB)

    Filippov, A.A.

    1985-07-01

    No existing numerical method of calculating electric fields in kinetical form allows simultaneous consideration of bias current and conductivity current. This article suggests a modification of the method of integral equations allowing computation of the field in imperfect media. The use of the method is said to be more effective than the method of equivalent discharges. The method suggested allows computation of the field while simultaneously considering conductivity current and permeability current. It also allows determination of the frequency characteristics of high voltage apparatus. Furthermore, it can be used to calculate various transient processes if the applied voltage is expanded into a Fourier series and calculations are performed individually for each member of the series.

  1. Electric Dipole Moment Experiment Systematic from Electric Field Discharge Current

    Science.gov (United States)

    Feinberg, B.; Gould, Harvey

    2014-09-01

    A magnetic field, in the direction of the electric field and synchronous with the electric field reversal, will mimic an EDM signal. One might expect a discharge across the electric field plates to produce magnetic fields with only small or vanishing components parallel to the electric field, minimizing its systematic effect. Our experimental model, using simulated discharge currents, found otherwise: the discharge current may be at an angle to the normal, and thus generate a normal magnetic field. Comparison of data from the experimental model with the results from calculations will be presented, along with estimates of the time-averaged normal magnetic field seen by atoms in an electron EDM experiment using a fountain of laser-cooled francium, as a function of discharge current.

  2. Dynamics of carbon nanotube alignment by electric fields

    International Nuclear Information System (INIS)

    The dynamics of multiwall carbon nanotube (MWCNT) alignment inside viscous media using electric fields is investigated. Electrical current measurements were performed in situ during the application of an electric field to liquid solutions of deionized water or dissolved polymer containing MWCNTs. The variation of electrical current over time was associated to the dynamics of the MWCNT network formation. The influence of the electric field magnitude and frequency on the MWCNT network formation was studied. MWCNT migration towards the negative electrode was observed when a direct current electric field was applied, whereas formation of an aligned MWCNT network was achieved for an alternating current electric field. The increase of the electric field frequency promotes a faster formation of an aligned MWCNT network and thinner MWCNT bundles. A higher viscosity of the liquid medium yields slower MWCNT alignment evidenced by a slower change of electrical current through the viscous system. An analytical model based on the dielectrophoresis-induced torque, which considers the viscosity of the medium, is also proposed to explain the dynamics of MWCNT alignment. Furthermore, aligned MWCNT/polysulfone solid composites were fabricated and electrically characterized. The solid composites presented anisotropic electrical conductivity, which was more evident for low MWCNT concentrations (0.1–0.2 wt%). (paper)

  3. Tuning Photoluminescence Response by Electric Field in Electrically Soft Ferroelectrics

    Science.gov (United States)

    Khatua, Dipak Kumar; Kalaskar, Abhijeet; Ranjan, Rajeev

    2016-03-01

    We show that an electrically soft ferroelectric host can be used to tune the photoluminescence (PL) response of rare-earth emitter ions by external electric field. The proof of this concept is demonstrated by changing the PL response of the Eu3 + ion by electric field on a model system Eu-doped 0.94 (Na1 /2Bi1 /2TiO3)-0.06 (BaTiO3) . We also show that new channels of radiative transitions, forbidden otherwise, open up due to positional disorder in the system, which can as well be tuned by electric field.

  4. Electric field effects on droplet burning

    Science.gov (United States)

    Patyal, Advitya; Kyritsis, Dimitrios; Matalon, Moshe

    2015-11-01

    The effects of an externally applied electric field are studied on the burning characteristics of a spherically symmetric fuel drop including the structure, mass burning rate and extinction characteristics of the diffusion flame. A reduced three-step chemical kinetic mechanism that reflects the chemi-ionization process for general hydrocarbon fuels has been proposed to capture the production and destruction of ions inside the flame zone. Due to the imposed symmetry, the effect of the ionic wind is simply to modify the pressure field. Our study thus focuses exclusively on the effects of Ohmic heating and kinetic effects on the burning process. Two distinguished limits of weak and strong field are identified, highlighting the relative strength of the internal charge barrier compared to the externally applied field, and numerically simulated. For both limits, significantly different charged species distributions are observed. An increase in the mass burning rate is noticed with increasing field in either limit with negligible change in the flame temperature. Increasing external voltages pushes the flame away from the droplet and causes a strengthening of the flame with a reduction in the extinction Damkhöler number.

  5. Discharge-generated electrical fields and electrical tree structures

    OpenAIRE

    L. A. Dissado; Fothergill, J; Bromley, K. S.

    1998-01-01

    The discharge-avalanche (D-A) model for electrical tree propagation in polymers is founded entirely upon basic physical concepts. Electrical discharges in an existing tree structure are taken to raise the electrical field in the polymer both along the discharge path and particularly at the tree tips. As a result of the field increase, electron multiplication avalanches occur within the polymer causing damage, possibly through ionisation of polymer molecules, which is accumulated over a period...

  6. Enhancement of antibacterial properties of Ag nanorods by electric field

    Energy Technology Data Exchange (ETDEWEB)

    Akhavan, Omid [Department of Physics, Sharif University of Technology, PO Box 11155-9161, Tehran (Iran, Islamic Republic of); Ghaderi, Elham [Tehran University of Medical Sciences, PO Box 14155-6447, Tehran (Iran, Islamic Republic of)], E-mail: oakhavan@sharif.edu

    2009-01-15

    The effect of an electric field on the antibacterial activity of columnar aligned silver nanorods was investigated. Silver nanorods with a polygonal cross section, a width of 20-60 nm and a length of 260-550 nm, were grown on a titanium interlayer by applying an electric field perpendicular to the surface of a Ag/Ti/Si(100) thin film during its heat treatment at 700 deg. C in an Ar+H{sub 2} environment. The optical absorption spectrum of the silver nanorods exhibited two peaks at wavelengths of 350 and 395 nm corresponding to the main surface plasmon resonance bands of the one-dimensional silver nanostructures. It was found that the silver nanorods with an fcc structure were bounded mainly by {l_brace}100{r_brace} facets. The antibacterial activity of the silver nanorods against Escherichia coli bacteria was evaluated at various electric fields applied in the direction of the nanorods without any electrical connection between the nanorods and the capacitor plates producing the electric field. Increasing the electric field from 0 to 50 V cm{sup -1} resulted in an exponential increase in the relative rate of reduction of the bacteria from 3.9x10{sup -2} to 10.5x10{sup -2} min{sup -1}. This indicates that the antibacterial activity of silver nanorods can be enhanced by applying an electric field, for application in medical and food-preserving fields.

  7. Galvanotactic behavior of Tetrahymena pyriformis under electric fields

    International Nuclear Information System (INIS)

    Tetrahymena pyriformis, a eukaryotic ciliate, swims toward a cathode in straight or cross-shaped microchannels under an applied electric field, a behavioral response called cathodal galvanotaxis. In straight channel experiments, a one-dimensional electric field was applied, and the galvanotactic swimming behavior of Tetrahymena pyriformis was observed and described in detail while the polarity of this field is switched. In most individual cases, the cell would immediately switch its direction toward the cathode; however, exceptional cases have been observed where cells exhibit a turning delay or do not turn after a polarity switch. In cross-channel experiments, feedback control using vision-based tracking was used to steer a cell in the microchannel intersection using a two-dimensional electric field generated by four electrodes placed at four ends of the cross channel. The motivation for this work is to study the swimming behavior of Tetrahymena pyriformis as a microrobot under the control of electric fields. (paper)

  8. Entanglement generation by electric field background

    Energy Technology Data Exchange (ETDEWEB)

    Ebadi, Zahra, E-mail: z.ebadi@ph.iut.ac.ir; Mirza, Behrouz, E-mail: b.mirza@cc.iut.ac.ir

    2014-12-15

    The quantum vacuum is unstable under the influence of an external electric field and decays into pairs of charged particles, a process which is known as the Schwinger pair production. We propose and demonstrate that this electric field can generate entanglement. Using the Schwinger pair production for constant and pulsed electric fields, we study entanglement for scalar particles with zero spins and Dirac fermions. One can observe the variation of the entanglement produced for bosonic and fermionic modes with respect to different parameters.

  9. Spin-current induced electric field

    OpenAIRE

    Sun, QF; Guo, H; Wang, J

    2003-01-01

    We theoretically investigate properties of the induced electric field of a steady-state spin-current without charge current, using an 'equivalent magnetic charge' method. Several general formula for the induced electric field are derived which play the role of 'Biot-Savart law' and 'Ampere's law.' Conversely, a moving spin is affected by an external electric field and we derive an expression for the interaction torque.

  10. Motional Spin Relaxation in Large Electric Fields

    OpenAIRE

    Schmid, Riccardo; Plaster, B; Filippone, B.W.

    2008-01-01

    We discuss the precession of spin-polarized Ultra Cold Neutrons (UCN) and $^{3}$He atoms in uniform and static magnetic and electric fields and calculate the spin relaxation effects from motional $v\\times E$ magnetic fields. Particle motion in an electric field creates a motional $v\\times E$ magnetic field, which when combined with collisions, produces variations of the total magnetic field and results in spin relaxation of neutron and $^{3}$He samples. The spin relaxation times $T_{1}$ (long...

  11. Comments on electric field experiments of positronium formation

    International Nuclear Information System (INIS)

    Validity of using static electric field in studying Ps formation mechanism is tested experimentally. At the present experimental condition, Ps intensity in low-density polyethylene was decreased seemingly in a similar way as a function of the strength of static and alternating electric fields. However, a time-dependent screening effect, possibly caused by accumulated charge, was apparent. By using an alternating field, it was possible to eliminate the screening effect. It is highly recommended to use alternating fields in the forthcoming electric field experiments. In another experiment, while applying alternating electric field, PAL was measured only when the polarity was positive or negative with respect to the positron implantation trajectory. The results showed that positive and negative fields have the same effect, indicating that the structure of terminal positron spur is symmetric, unlike the asymmetric structure at the end of muon track

  12. Ferromagnetic Liquid Thin Films Under Applied Field

    OpenAIRE

    Banerjee, S.; Widom, M.

    1999-01-01

    Theoretical calculations, computer simulations and experiments indicate the possible existence of a ferromagnetic liquid state, although definitive experimental evidence is lacking. Should such a state exist, demagnetization effects would force a nontrivial magnetization texture. Since liquid droplets are deformable, the droplet shape is coupled with the magnetization texture. In a thin-film geometry in zero applied field, the droplet has a circular shape and a rotating magnetization texture ...

  13. Thermodynamics of ferrofluids in applied magnetic fields.

    Science.gov (United States)

    Elfimova, Ekaterina A; Ivanov, Alexey O; Camp, Philip J

    2013-10-01

    The thermodynamic properties of ferrofluids in applied magnetic fields are examined using theory and computer simulation. The dipolar hard sphere model is used. The second and third virial coefficients (B(2) and B(3)) are evaluated as functions of the dipolar coupling constant λ, and the Langevin parameter α. The formula for B(3) for a system in an applied field is different from that in the zero-field case, and a derivation is presented. The formulas are compared to results from Mayer-sampling calculations, and the trends with increasing λ and α are examined. Very good agreement between theory and computation is demonstrated for the realistic values λ≤2. The analytical formulas for the virial coefficients are incorporated in to various forms of virial expansion, designed to minimize the effects of truncation. The theoretical results for the equation of state are compared against results from Monte Carlo simulations. In all cases, the so-called logarithmic free energy theory is seen to be superior. In this theory, the virial expansion of the Helmholtz free energy is re-summed in to a logarithmic function. Its success is due to the approximate representation of high-order terms in the virial expansion, while retaining the exact low-concentration behavior. The theory also yields the magnetization, and a comparison with simulation results and a competing modified mean-field theory shows excellent agreement. Finally, the putative field-dependent critical parameters for the condensation transition are obtained and compared against existing simulation results for the Stockmayer fluid. Dipolar hard spheres do not undergo the transition, but the presence of isotropic attractions, as in the Stockmayer fluid, gives rise to condensation even in zero field. A comparison of the relative changes in critical parameters with increasing field strength shows excellent agreement between theory and simulation, showing that the theoretical treatment of the dipolar interactions

  14. Formation of Organized Protein Thin Films with External Electric Field.

    Science.gov (United States)

    Ferreira, Cecília Fabiana da G; Camargo, Paulo C; Benelli, Elaine M

    2015-10-01

    The effect of an external electric field on the formation of protein GlnB-Hs films and on its buffer solution on siliconized glass slides has been analyzed by current versus electric field curves and atomic force microscopy (AFM). The Herbaspirillum seropedicae GlnB protein (GlnB-Hs) is a globular, soluble homotrimer (36 kDa) with its 3-D structure previously determined. Concentrations of 10 nM native denatured GlnB-Hs protein were deposited on siliconized glass slides under ambient conditions. Immediately after solution deposition a maximum electric field of 30 kV/m was applied with rates of 3 V/s. The measured currents were surface currents and were analyzed as transport current. Electric current started to flow only after a minimum electric field (critical value) for the systems analyzed. The AFM images showed films with a high degree of directional organization only when the proteins were present in the solution. These results showed that the applied electric field favored directional organization of the protein GlnB-Hs films and may contribute to understand the formation of protein films under applied electric fields.

  15. Remote Educational Experiment Applied To Electrical Engineering

    Directory of Open Access Journals (Sweden)

    João Mota Neto

    2013-02-01

    Full Text Available This article presents the development of an architecture for a remote educational experiment concerning the speed control applied to a direct current motor. The proposed architecture is based on the use of an Arduino Uno and Ethernet Shield, whose function is to interface between the experiment and the Internet. The user can access the control experiment through an application developed in Java, which allows the students to choose the model of the controller (P, PI and PID they want to study, change its parameters and the system response visualization through graphics and webcam. Results show the potential of the application of such architecture to remote experimentation context concerning engineering, mainly to the specific area of control systems.

  16. AC Electric Fields Drive Steady Flows in Flames

    OpenAIRE

    Drews, Aaron M.; Cademartiri, Ludovico; Chemama, Michael Leopold; Brenner, Michael P.; Whitesides, George M.; Bishop, Kyle J. M.

    2012-01-01

    We show that time-oscillating electric fields applied to plasmas present in flames create steady flows of gas. Ions generated within the flame move in the field and migrate a distance δ before recombining; the net flow of ions away from the flame creates a time-averaged force that drives the steady flows observed experimentally. A quantitative model describes the response of the flame and reveals how δ decreases as the frequency of the applied field increases. Interestingly, above a critical ...

  17. Positrons trapped in polyethylene: Electric field effect

    International Nuclear Information System (INIS)

    The intensity of the iot2-component of positrons annihilated in polyethylene is found to increase with increasing electric field, while the formation probability of the positron state responsible for this component remains independent of the field. (orig.) 891 HPOE

  18. Enhanced electrical properties of ferroelectric thin films with electric field induced domain control

    International Nuclear Information System (INIS)

    (0 0 1) oriented Pb(Zr0.5Ti0.5)O3 (PZT) thin films with high piezoelectric constant were deposited by the electric field-assisted annealing (EFA-A) of alkoxide-derived precursor thin films. So far, selective orientation control of (0 0 1) domain and (1 0 0) domain is very difficult, especially for the chemical solution deposition (CSD). We tried an electric field induced domain control to improve the electrical properties with CSD. An electric field of 10 kV/cm has been applied during an annealing. The high (0 0 1) domain ratio of 75.6% was obtained from the deconvolution of (0 0 2) and (2 0 0) X-ray diffraction peaks. The PZT thin films showed very high piezoelectric constant of 352 pm/V. This shows electric field induced domain control is very effective to enhance the electrical properties of CSD-derived PZT thin films.

  19. Radial electric fields for improved tokamak performance

    International Nuclear Information System (INIS)

    The influence of externally-imposed radial electric fields on the fusion energy output, energy multiplication, and alpha-particle ash build-up in a TFTR-sized, fusing tokamak plasma is explored. In an idealized tokamak plasma, an externally-imposed radial electric field leads to plasma rotation, but no charge current flows across the magnetic fields. However, a realistically-low neutral density profile generates a non-zero cross-field conductivity and the species dependence of this conductivity allows the electric field to selectively alter radial particle transport

  20. External Horizontally Uniform Magnetic Field Applied to Steel Solidification

    Science.gov (United States)

    Mechighel, Farid; Kadja, Mahfoud

    Based on continuum model, a mathematical model for convection flow during directional solidification of steel, Fe-0.42wt%C, in an applied magnetic field is presented. The model includes mass, momentum, energy, species and electrical potential conservation equations. The geometry under study is rectangular. The permeability in the mushy zone is treated by means of the Blake-Kozeny equation. The system of equation has been discretized by means of Finite volume method. For solution of discretized equations SIMPLER Algorithm is used. The results show the strong effect of the magnetic field on the solidification process.

  1. Essays in Applied Microeconomics With Application to Electricity Markets

    OpenAIRE

    Richter, Jan

    2013-01-01

    The thesis consists of three parts dealing with both game theoretic and general equilibrium models, which were originally motivated by research questions regarding liberalized electricity markets. However, the model frameworks developed can more or less be applied to other industries as well. In Chapter 2, I study two electricity markets connected by a fixed amount of crossborder capacity. The total amount of capacity is known to all electricity traders and allocated via an auction. The c...

  2. Rotating artificial gauge magnetic and electric fields

    CERN Document Server

    Lembessis, V E; Alshamari, S; Siddig, A; Aldossary, O M

    2016-01-01

    We consider the creation of artificial gauge magnetic and electric fields created when a two-level atom interacts with an optical Ferris wheel light field.These fields have the spatial structure of the optical Ferris wheel field intensity profile. If this optical field pattern is made to rotate in space then we have the creation of artificial electromagnetic fields which propagate in closed paths. The properties of such fields are presented and discussed

  3. The electric field effect and electromagnetic wave emission in intrinsic Josephson junctions

    Science.gov (United States)

    Koyama, T.

    2013-04-01

    We formulate a theory for the electric field effect in intrinsic Josephson junctions (IJJs). The coupled dynamical equations for the phase differences are derived in the presence of both a bias current and an applied electric field on the basis of the capacitively-coupled IJJ model. It is shown that the current-voltage characteristics of the IJJs sensitively depend on the applied electric field. The dipole emission originating from the electric field effect is also predicted.

  4. Electron electric-dipole-moment experiment using electric-field quantized slow cesium atoms

    International Nuclear Information System (INIS)

    A proof-of-principle electron electric-dipole-moment (e-EDM) experiment using slow cesium atoms, nulled magnetic fields, and electric-field quantization has been performed. With the ambient magnetic fields seen by the atoms reduced to less than 200 pT, an electric field of 6 MV/m lifts the degeneracy between states of unequal |mF| and, along with the low (≅3 m/s) velocity, suppresses the systematic effect from the motional magnetic field. The low velocity and small residual magnetic field have made it possible to induce transitions between states and to perform state preparation, analysis, and detection in regions free of applied static magnetic and electric fields. This experiment demonstrates techniques that may be used to improve the e-EDM limit by two orders of magnitude, but it is not in itself a sensitive e-EDM search, mostly due to limitations of the laser system

  5. Electron electric dipole moment experiment using electric-field quantized slow cesium atoms

    CERN Document Server

    Amini, Jason M; Gould, Harvey

    2007-01-01

    A proof-of-principle electron electric dipole moment (e-EDM) experiment using slow cesium atoms, nulled magnetic fields, and electric field quantization has been performed. With the ambient magnetic fields seen by the atoms reduced to less than 200 pT, an electric field of 6 MV/m lifts the degeneracy between states of unequal mF and, along with the low (approximately 3 m/s) velocity, suppresses the systematic effect from the motional magnetic field. The low velocity and small residual magnetic field have made it possible to induce transitions between states and to perform state preparation, analysis, and detection in regions free of applied static magnetic and electric fields. This experiment demonstrates techniques that may be used to improve the e-EDM limit by two orders of magnitude, but it is not in itself a sensitive e-EDM search, mostly due to limitations of the laser system.

  6. Pulsed electric field inactivation in a microreactor

    NARCIS (Netherlands)

    Fox, M.B.

    2006-01-01

    Pulsed electric fields (PEF) is a novel, non-thermal pasteurization method which uses short, high electric field pulses to inactivate microorganisms. The advantage of a pasteurization method like PEF compared to regular heat pasteurization is that the taste, flavour, texture and nutritional value ar

  7. The convection electric field in auroral substorms

    DEFF Research Database (Denmark)

    Gjerløv, Jesper Wittendorff; Hoffman, R.A.

    2001-01-01

    Dynamics Explorer 2 (DE 2) electric field and ion drift data are used in a statistical study of the ionospheric convection electric field in bulge-type auroral substorms. Thirty-one individual DE 2 substorm crossings were carefully selected and organized by the use of global auroral images obtained...... this database enabled us to compile a model of the ionospheric convection electric field. The characteristics of the premidnight convection reversal show a pronounced local time dependency. Far west of the surge it is a fairly well defined point reversal or convection shear. Approaching the surge and within...... the surge it is a region of weak electric fields increasing in width toward midnight that separates regions of equatorward and poleward electric fields. Therefore we adopt the term Harang region rather than the Harang discontinuity for the premidnight convection reversal. A relatively narrow convection...

  8. High diffraction efficiency in SBN with applied fields near the coercive field

    Science.gov (United States)

    Sarvestani, S. S.; Siahmakoun, A.; Duree, G.; Johnson, K.

    2001-05-01

    We present the experiments and results of our investigation of electrical fixing in SBN:60. We propose an optical method for determining the value of the coercive field in ferroelectric crystals. An interferometric method is used to map the change in the index of refraction with negative applied fields, where the minimum of the index change is an indication of the coercive field. From this experiment, values of 1.55 kV±20 V for the coercive voltage and 147±6 pm/V for the linear electro-optic coefficient are found. Two electrical-fixing techniques that result in very high diffraction efficiencies are presented, discussed and compared to previous publications on electrical fixing in SBN. High diffraction efficiencies of about 95% were achieved with the application of negative fields near the coercive region, during and after holographic recording in the crystal.

  9. On the influence of applied fields on spinel formation

    Energy Technology Data Exchange (ETDEWEB)

    KORTE,C.; FARER,J.K.; RAVISHANKAR,N.; MICHAEL,JOSEPH R.; SCHMALZRIED,J.; CARTER,C.B.

    2000-04-04

    Interfaces play an important role in determining the effect of electric fields on the mechanism of the formation spinel by solid-state reaction. The reaction occurs by the movement of phase boundaries but the rate of this movement can be affected by grain boundaries in the reactants or in the reaction product. Only by understanding these relationships will it be possible to engineer their behavior. As a particular example of such a study, MgIn{sub 2}O{sub 4} can be formed by the reaction between single-crystal MgO substrate and a thin film of In{sub 2}O{sub 3} with or without an applied electric field. High-resolution backscattered electron (BSE) imaging and electron backscattered diffraction (EBSD) in a scanning electron microscope (SEM) has been used to obtain complementary chemical and crystallographic information.

  10. Electric Field Induced Selective Disordering in Lamellar Block Copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Ruppel, Markus A [ORNL; Pester, Christian W [ORNL; Langner, Karol M [Leiden Institute of Chemistry, Leiden University, The Netherlands; Sevink, Geert [Leiden Institute of Chemistry, Leiden University, The Netherlands; Schoberth, Heiko [University of Bayreuth; Schmidt, Kristin [ORNL; Urban, Volker S [ORNL; Mays, Jimmy [ORNL; Boker, Alexander [RWTH Aachen University

    2013-01-01

    External electric fields align nanostructured block copolymers by either rotation of grains or nucleation and growth depending on how strongly the chemically distinct block copolymer components are segregated. In close vicinity to the orderdisorder transition, theory and simulations suggest a third mechanism: selective disordering. We present a time-resolved small-angle X-ray scattering study that demonstrates how an electric field can indeed selectively disintegrate ill-aligned lamellae in a lyotropic block copolymer solution, while lamellae with interfaces oriented parallel to the applied field prevail. The present study adds an additional mechanism to the experimentally corroborated suite of mechanistic pathways, by which nanostructured block copolymers can align with an electric field. Our results further unveil the benefit of electric field assisted annealing for mitigating orientational disorder and topological defects in block copolymer mesophases, both in close vicinity to the orderdisorder transition and well below it.

  11. Hydrogel Actuation by Electric Field Driven Effects

    Science.gov (United States)

    Morales, Daniel Humphrey

    the applied electric field. We extend the use of ionoprinting to develop multi-responsive bilayer gel systems capable of more complex shape transformation. The localized crosslinked regions determine the bending axis as the gel responds to the external environment. The bending can be tuned to reverse direction isothermally by changing the solvent quality or by changing the temperature at a fixed concentration. The multi-responsive behavior is caused by the volume transitions of a non-ionic, thermos-sensitive hydrogel coupled with a superabsorbent ionic hydrogel. Lastly, electric field driven microparticle assembly, using dielectrophoretic (DEP) forces, organized colloidal microparticles within a hydrogel matrix. The use of DEP forces enables rapid, efficient and precise control over the colloidal distribution. The resulting supracolloidal endoskeleton structures impart directional bending as the hydrogel shrinks. We compare the ordered particles structures to random particle distributions in affecting the hydrogel sheet bending response. This study demonstrates a universal technique for imparting directional properties in hydrogels towards new generations of hybrid soft materials.

  12. Nonpremixed flame in a counterflow under electric fields

    KAUST Repository

    Park, Daegeun

    2016-05-08

    Electrically assisted combustion has been studied in order to control or improve flame characteristics, and emphasizing efficiency and emission regulation. Many phenomenological observations have been reported on the positive impact of electric fields on flame, however there is a lack of detailed physical mechanisms for interpreting these. To clarify the effects of electric fields on flame, I have investigated flame structure, soot formation, and flow field with ionic wind electrical current responses in nonpremixed counterflow flames. The effects of direct current (DC) electric field on flame movement and flow field was also demonstrated in premixed Bunsen flames. When a DC electric field was applied to a lower nozzle, the flames moved toward the cathode side due to Lorentz force action on the positive ions, soot particles simultaneously disappeared completely and laser diagnostics was used to identify the results from the soot particles. To understand the effects of an electric field on flames, flow visualization was performed by Mie scattering to check the ionic wind effect, which is considered to play an important role in electric field assisted combustion. Results showed a bidirectional ionic wind, with a double-stagnant flow configuration, which blew from the flame (ionic source) toward both the cathode and the anode. This implies that the electric field affects strain rate and the axial location of stoichiometry, important factors in maintaining nonpremixed counterflow flames; thus, soot formation of the counterflow flame can also be affected by the electric field. In a test of premixed Bunsen flames having parallel electrodes, flame movement toward the cathode and bidirectional ionic wind were observed. Using PIV measurement it was found that a created radial velocity caused by positive ions (i.e. toward a cathode), was much faster than the velocity toward the anode. Even in a study of alternating current (AC) electric fields, bidirectional ionic wind could

  13. Electric fields in the middle atmosphere

    Science.gov (United States)

    Holzworth, Robert H.

    1987-01-01

    Middle atmospheric electrodynamics is characterized by discussing the present understanding of the background electrical conductivity and the sources for electric fields and currents within the medium. Results of recent research that contradicts the historical view of the region are presented. Of principal interest to the present direction of the field is the attempt to quantize the low and high altitude electric generators such as thunderstorms or ionospheric convection. It is noted that the many-fold increase in available electric parameter data from within the middle atmosphere has been a great stimulus to recent research; however, these measurements have tended to raise more questions than they give answers.

  14. Electric field and temperature effects in irradiated MOSFETs

    Science.gov (United States)

    Silveira, M. A. G.; Santos, R. B. B.; Leite, F. G.; Araújo, N. E.; Cirne, K. H.; Melo, M. A. A.; Rallo, A.; Aguiar, Vitor. A. P.; Aguirre, F.; Macchione, E. L. A.; Added, N.; Medina, N. H.

    2016-07-01

    Electronic devices exposed to ionizing radiation exhibit degradation on their electrical characteristics, which may compromise the functionality of the device. Understanding the physical phenomena responsible for radiation damage, which may be specific to a particular technology, it is of extreme importance to develop methods for testing and recovering the devices. The aim of this work is to check the influence of thermal annealing processes and electric field applied during irradiation of Metal Oxide Semiconductor Field Effect Transistors (MOSFET) in total ionizing dose experiments analyzing the changes in the electrical parameters in these devices

  15. Migration of amoeba cells in an electric field

    Science.gov (United States)

    Guido, Isabella; Bodenschatz, Eberhard

    2015-03-01

    Exogenous and endogenous electric fields play a role in cell physiology as a guiding mechanism for the orientation and migration of cells. Electrotaxis of living cells has been observed for several cell types, e.g. neurons, fibroblasts, leukocytes, neural crest cells, cancer cells. Dictyostelium discoideum (Dd), an intensively investigated chemotactic model organism, also exhibits a strong electrotactic behavior moving toward the cathode under the influence of electric fields. Here we report experiments on the effects of DC electric fields on the directional migration of Dd cells. We apply the electric field to cells seeded into microfluidic devices equipped with agar bridges to avoid any harmful effects of the electric field on the cells (ions formation, pH changes, etc.) and a constant flow to prevent the build-up of chemical gradient that elicits chemotaxis. Our results show that the cells linearly increase their speed over time when a constant electric field is applied for a prolonged duration (2 hours). This novel phenomenon cannot be attributed to mechanotaxis as the drag force of the electroosmotic flow is too small to produce shear forces that can reorient cells. It is independent of the cellular developmental stage and to our knowledge, it was not observed in chemotaxis. This work is supported by MaxSynBio project of the Max Planck Society.

  16. Effect of superheat and electric field on saturated film boiling

    Science.gov (United States)

    Pandey, Vinod; Biswas, Gautam; Dalal, Amaresh

    2016-05-01

    The objective of this investigation is to study the influence of superheat temperature and applied uniform electric field across the liquid-vapor interface during film boiling using a coupled level set and volume of fluid algorithm. The hydrodynamics of bubble growth, detachment, and its morphological variation with electrohydrodynamic forces are studied considering the medium to be incompressible, viscous, and perfectly dielectric at near critical pressure. The transition in interfacial instability behavior occurs with increase in superheat, the bubble release being periodic both in space and time. Discrete bubble growth occurs at a smaller superheat whereas vapor columns form at the higher superheat values. Destabilization of interfacial motion due to applied electric field results in decrease in bubble separation distance and increase in bubble release rate culminating in enhanced heat transfer rate. A comparison of maximum bubble height owing to application of different intensities of electric field is performed at a smaller superheat. The change in dynamics of bubble growth due to increasing superheat at a high intensity of electric field is studied. The effect of increasing intensity of electric field on the heat transfer rate at different superheats is determined. The boiling characteristic is found to be influenced significantly only above a minimum critical intensity of the electric field.

  17. Communication: Control of chemical reactions using electric field gradients

    Science.gov (United States)

    Deshmukh, Shivaraj D.; Tsori, Yoav

    2016-05-01

    We examine theoretically a new idea for spatial and temporal control of chemical reactions. When chemical reactions take place in a mixture of solvents, an external electric field can alter the local mixture composition, thereby accelerating or decelerating the rate of reaction. The spatial distribution of electric field strength can be non-trivial and depends on the arrangement of the electrodes producing it. In the absence of electric field, the mixture is homogeneous and the reaction takes place uniformly in the reactor volume. When an electric field is applied, the solvents separate and the reactants are concentrated in the same phase or separate to different phases, depending on their relative miscibility in the solvents, and this can have a large effect on the kinetics of the reaction. This method could provide an alternative way to control runaway reactions and to increase the reaction rate without using catalysts.

  18. Spiral Wave Generation in a Vortex Electric Field

    Institute of Scientific and Technical Information of China (English)

    YUAN Xiao-Ping; CHEN Jiang-Xing; ZHAO Ye-Hua; LOU Qin; WANG Lu-Lu; SIIEN Qian

    2011-01-01

    The effect of a vortical electric field on nonlinear patterns in excitable media is studied. When an appropriate vortex electric field is applied, the system exhibits pattern transition from chemical turbulence to spiral waves, which possess the same chtality as the vortex electric field. The underlying mechanism of this is discussed. We also show the meandering behavior of a spiral under the taming of a vortex electric field. The results obtained here may contribute to control strategies of patterns on surface reaction.%The effect of a vortical electric field on nonlinear patterns in excitable media is studied.When an appropriate vortex electric field is applied,the system exhibits pattern transition from chemical turbulence to spiral waves,which possess the same chirality as the vortex electric field.The underlying mechanism of this is discussed.We also show the meandering behavior of a spiral under the taming of a vortex electric field.The results obtained here may contribute to control strategies of patterns on surface reaction.Spiral waves are one of the most common and widely studied patterns in nature.They appear in hydrodynamic systems,chemical reactions and a large variety of biological,chemical and physical systems.[1-5] Much attention has been paid to their rich nonlinear dynamics,as well as potential applications in various biological or physiological systems,since the emergence and instability of spirals usually lead to abnormal states,for example in cardiac arrythmia[6,7] and epilepsy[8].Much research has been carried out in studying pattern formations in catalytic CO oxidation on Pt(110),[9-11] because they provide practical utilization in industry.A rich variety of spatiotemporal patterns,including travelling pulses,standing waves,target patterns,spiral waves and chemical turbulence have been observed in this system.[12-16

  19. Pulsed electric field inactivation in a microreactor

    OpenAIRE

    Fox, M.B.

    2006-01-01

    Pulsed electric fields (PEF) is a novel, non-thermal pasteurization method which uses short, high electric field pulses to inactivate microorganisms. The advantage of a pasteurization method like PEF compared to regular heat pasteurization is that the taste, flavour, texture and nutritional value are much less affected. At the moment, the PEF process faces several challenges, to which microtechnology could be an aid. The small electrode distance in microtechnological reactors enables the use ...

  20. GEM Detector Electric Field Simulation

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    GEM (Gas Electron Multiplier) detectors have been widely employed in the experimental field of high energy physics and nuclear physics. As a successor to drift chambers, GEMs are much easier to fabricate and have a much higher spatial resolution

  1. Tuning bimolecular chemical reactions by electric fields

    CERN Document Server

    Tscherbul, Timur V

    2014-01-01

    We develop a theoretical method for solving the quantum mechanical reactive scattering problem in the presence of external fields based on a hyperspherical coordinate description of the reaction complex combined with the total angular momentum representation for collisions in external fields. The method allows us to obtain converged results for the chemical reaction LiF + H -> Li + HF in an electric field. Our calculations demonstrate that, by inducing couplings between states of different total angular momenta, electric fields with magnitudes <150 kV/cm give rise to resonant scattering and a significant modification of the total reaction probabilities, product state distributions and the branching ratios for reactive vs inelastic scattering.

  2. Effect of vacancy defect on electrical properties of chiral single-walled carbon nanotube under external electrical field

    Institute of Scientific and Technical Information of China (English)

    Luo Yu-Pin; Tien Li-Gan; Tsai Chuen-Horng; Lee Ming-Hsien; Li Feng-Yin

    2011-01-01

    Ab initio calculations demonstrated that the energy gap modulation of a chiral carbon nanotube with monovacancy defect can be achieved by applying a transverse electric field. The bandstructure of this defective carbon nanotube varying due to the external electric field is distinctly different from those of the perfect nanotube and defective zigzag nanotube. This variation in bandstructure strongly depends on not only the chirality of the nanotube and also the applied direction of the transverse electric field. A mechanism is proposed to explain the response of the local energy gap between the valence band maximum state and the local gap state under external electric field. Several potential applications of these phenomena are discussed.

  3. Electric and magnetic fields in medicine and biology

    International Nuclear Information System (INIS)

    Papers Include: The effects of low frequency (50 Hz) magnetic fields on neuro-chemical transmission in vitro; Morphological changes in E Coli subjected to DC electrical fields; An investigation of some claimed biological effects of electromagnetic fields; Electrical phenomena and bone healing - a comparison of contemporary techniques; Clinical evaluations of a portable module emitting pulsed RF energy; The design, construction and performance of a magnetic nerve stimulator; The principle of electric field tomography and its application to selective read-out of information from peripheral nerves; Applied potential tomography - clinical applications; Impendance imaging using a linear electrode array; Mathematics as an aid to experiment: human body currents induced by power frequency electric fields; Effects of electric field near 750KV transmission line and protection against their harmful consequences; Leukemia and electromagnetic fields: a case-control study; Overhead power lines and childhood cancer; Magnetic measurement of nerve action currents - a new intraoperative recording technique; The potential use of electron spin resonance or impedance measurement to image neuronal electrical activity in the human brain

  4. Rotating Capacitor Measures Steady Electric Fields

    Science.gov (United States)

    Johnston, A. R.; Kirkham, H.; Eng, B.

    1986-01-01

    Portable sensor measures electric fields created by dc powerlines or other dc-high-voltage sources. Measures fields from 70 to 50,000 V/m with linearity of 2 percent. Sensor used at any height above ground. Measures both magnitude and direction of field and provides signals representing these measurements to remote readout device. Sensor functions with minimal disturbance of field it is measuring.

  5. Capillary bridges in electric fields

    NARCIS (Netherlands)

    Klingner, Anke; Buehrle, Juergen; Mugele, Frieder

    2004-01-01

    We analyzed the morphology of droplets of conductive liquids placed between two parallel plate electrodes as a function of the two control parameters electrode separation and applied voltage. Both electrodes were covered by thin insulating layers, as in conventional electrowetting experiments. Depen

  6. Midday reversal of equatorial ionospheric electric field

    Directory of Open Access Journals (Sweden)

    R. G. Rastogi

    Full Text Available A comparative study of the geomagnetic and ionospheric data at equatorial and low-latitude stations in India over the 20 year period 1956–1975 is described. The reversal of the electric field in the ionosphere over the magnetic equator during the midday hours indicated by the disappearance of the equatorial sporadic E region echoes on the ionograms is a rare phenomenon occurring on about 1% of time. Most of these events are associated with geomagnetically active periods. By comparing the simultaneous geomagnetic H field at Kodaikanal and at Alibag during the geomagnetic storms it is shown that ring current decreases are observed at both stations. However, an additional westward electric field is superimposed in the ionosphere during the main phase of the storm which can be strong enough to temporarily reverse the normally eastward electric field in the dayside ionosphere. It is suggested that these electric fields associated with the V×Bz electric fields originate at the magnetopause due to the interaction of the solar wind and the interplanetary magnetic field.

  7. Method of using an electric field controlled emulsion phase contactor

    Science.gov (United States)

    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.

  8. Nanoparticle Near-Surface Electric Field.

    Science.gov (United States)

    Chkhartishvili, Levan

    2016-12-01

    Theoretical studies show that surface reconstruction in some crystals involves splitting the surface atomic layer into two-upper and lower-sublayers consisting of atoms with only positive or only negative effective electric charges, respectively. In a macroscopic crystal with an almost infinite surface, the electric field induced by such a surface-dipole is practically totally concentrated between the sublayers. However, when the material is powdered and its particles are of sufficiently small sizes, an electric field of a significant magnitude can be induced outside the sublayers as well. We have calculated the distribution of the electric field and its potential induced at the surface of a disc-shaped particle. The suggested novel nanoscale effect explains the increase in physical reactivity of nanopowders with decreasing particle sizes. PMID:26831686

  9. Rotationally Vibrating Electric-Field Mill

    Science.gov (United States)

    Kirkham, Harold

    2008-01-01

    A proposed instrument for measuring a static electric field would be based partly on a conventional rotating-split-cylinder or rotating-split-sphere electric-field mill. However, the design of the proposed instrument would overcome the difficulty, encountered in conventional rotational field mills, of transferring measurement signals and power via either electrical or fiber-optic rotary couplings that must be aligned and installed in conjunction with rotary bearings. Instead of being made to rotate in one direction at a steady speed as in a conventional rotational field mill, a split-cylinder or split-sphere electrode assembly in the proposed instrument would be set into rotational vibration like that of a metronome. The rotational vibration, synchronized with appropriate rapid electronic switching of electrical connections between electric-current-measuring circuitry and the split-cylinder or split-sphere electrodes, would result in an electrical measurement effect equivalent to that of a conventional rotational field mill. A version of the proposed instrument is described.

  10. Effect of AC electric fields on flame spread over electrical wire

    KAUST Repository

    Kim, Minkuk

    2011-01-01

    The effect of electric fields on the characteristics of flame spread over insulated electrical wire has been investigated experimentally by varying AC voltage and frequency applied to the wire in the normal gravity condition. The polyethylene (PE) insulated electrical wire was placed horizontally on electrically non-conducting posts and one end of the wire was connected to the high voltage terminal. Thus, the electrical system is the single electrode configuration. The wire was ignited at one end and the flame spread rate along the wire has been measured from the images using a video camera. Two distinct regimes existed depending on the applied AC frequency. In the low frequency regime, the flame spread rate decreased with the frequency and voltage. While in the high frequency regime, it decreased initially with voltage and then increased. At high frequency, the spread rate was even over that without applying electric fields. This result implies that fire safety codes developed without considering the effect of electric fields may require modifications. © 2010 Published by Elsevier Inc. on behalf of The Combustion Institute. All rights reserved.

  11. Effects of high external electric fields on protein conformation

    Science.gov (United States)

    Pompa, Pier Paolo; Bramanti, Alessandro; Maruccio, Giuseppe; del Mercato, Loretta Laureana; Chiuri, Rocco; Cingolani, Roberto; Rinaldi, Ross

    2005-06-01

    Resistance of biomolecules to high electric fields is a main concern for nanobioelectronics/nanobiosensing applications, and it is also a relevant issue from a fundamental perspective, to understand the dielectric properties and structural dynamics of proteins. In nanoscale devices, biomolecules may experience electric fields as high as 107 V/m in order to elicit charge transport/transfer. Understanding the effects of such fields on their structural integrity is thus crucial to assess the reliability of biomolecular devices. In this study, we show experimental evidence for the retention of native-like fold pattern by proteins embedded in high electric fields. We have tested the metalloprotein azurin, deposited onto SiO2 substrates in air with proper electrode configuration, by applying high static electric fields (up to 106-107 V/m). The effects on the conformational properties of protein molecules have been determined by means of intrinsic fluorescence measurements. Experimental results indicate that no significant field-induced conformational alteration occurs. This behavior is also discussed and supported by theoretical predictions of the intrinsic intra-protein electric fields. As the general features of such inner fields are not peculiar of azurin, the conclusions presented here should have general validity.

  12. Effect of Electric Field on Outwardly Propagating Spherical Flame

    KAUST Repository

    Mannaa, Ossama

    2012-06-01

    The thesis comprises effects of electric fields on a fundamental study of spheri­cal premixed flame propagation.Outwardly-propagating spherical laminar premixed flames have been investigated in a constant volume combustion vessel by applying au uni-directional electric potential.Direct photography and schlieren techniques have been adopted and captured images were analyzed through image processing. Unstretched laminar burning velocities under the influence of electric fields and their associated Markstein length scales have been determined from outwardly prop­agating spherical flame at a constant pressure. Methane and propane fuels have been tested to assess the effect of electric fields on the differential diffusion of the two fuels.The effects of varying equivalence ratios and applied voltages have been in­vestigated, while the frequency of AC was fixed at 1 KHz. Directional propagating characteristics were analyzed to identify the electric filed effect. The flame morphology varied appreciably under the influence of electric fields which in turn affected the burning rate of mixtures.The flame front was found to propagate much faster toward to the electrode at which the electric fields were supplied while the flame speeds in the other direction were minimally influenced. When the voltage was above 7 KV the combustion is markedly enhanced in the downward direction since intense turbulence is generated and as a result the mixing process or rather the heat and mass transfer within the flame front will be enhanced.The com­bustion pressure for the cases with electric fields increased rapidly during the initial stage of combustion and was relatively higher since the flame front was lengthened in the downward direction.

  13. Computer Simulation of Electric Field Lines.

    Science.gov (United States)

    Kirkup, L.

    1985-01-01

    Describes a computer program which plots electric field line plots. Includes program listing, sample diagrams produced on a BBC model B microcomputer (which could be produced on other microcomputers by modifying the program), and a discussion of the properties of field lines. (JN)

  14. Electric field measurements from Halley, Antarctica

    Science.gov (United States)

    Nicoll, Keri; Harrison, R. Giles

    2016-04-01

    Antarctica is a unique location for the study of atmospheric electricity. Not only is it one of the most pollutant free places on Earth, but its proximity to the south magnetic pole means that it is an ideal location to study the effects of solar variability on the atmospheric electric field. This is due to the reduced shielding effect of the geomagnetic field at the poles which leads to a greater flux of incoming Galactic Cosmic Rays (GCRs) as well as an increased probability of energetic particle precipitation from SEPs and relativistic electrons. To investigate such effects, two electric field mills of different design were installed at the British Antarctic Survey Halley base in February 2015 (75. 58 degrees south, 26.66 degrees west). Halley is situated on the Brunt Ice Shelf in the south east of the Weddell Sea and has snow cover all year round. Preliminary analysis has focused on selection of fair weather criteria using wind speed and visibility measurements which are vital to assess the effects of falling snow, blowing snow and freezing fog on the electric field measurements. When the effects of such adverse weather conditions are removed clear evidence of the characteristic Carnegie Curve diurnal cycle exists in the Halley electric field measurements (with a mean value of 50V/m and showing a 40% peak to peak variation in comparison to the 34% variation in the Carnegie data). Since the Carnegie Curve represents the variation in thunderstorm activity across the Earth, its presence in the Halley data confirms the presence of the global atmospheric electric circuit signal at Halley. The work presented here will discuss the details of the Halley electric field dataset, including the variability in the fair weather measurements, with a particular focus on magnetic field fluctuations.

  15. Stratospheric electric field measurements with transmediterranean balloons

    Science.gov (United States)

    de La Morena, B. A.; Alberca, L. F.; Curto, J. J.; Holzworth, R. H.

    1993-01-01

    The horizontal component of the stratospheric electric field was measured using a balloon in the ODISEA Campaign of Transmediterranean Balloon Program. The balloon flew between Trapani (Sicily) and El Arenosillo (Huelva, Spain) along the 39 deg N parallel at a height between 34 and 24 km. The high values found for the field on fair-weather and its quasi-turbulent variation, both in amplitude and direction, are difficult to explain with the classical electric field source. A new source, first described by Holzworth (1989), is considered as possibly causing them.

  16. On the first Townsend coefficient at high electric field

    OpenAIRE

    Davydov, Yu. I.

    2004-01-01

    Based on the simplified approach it is shown and experimentally confirmed that gas gain in wire chambers at very low pressure becomes higher on thicker wires at the same applied high voltage. This is a consequence of the fact that the first Townsend coefficient at high reduced electric field depends almost entirely on the mean free path of electrons.

  17. On the first Townsend coefficient at high electric field

    CERN Document Server

    Davydov, Y I

    2004-01-01

    For the first time it is shown and experimentally confirmed that gas gain in wire chambers at very low pressure become higher on thicker wires at the same applied high voltage. This is a consequence of the fact that the first Townsend coefficient at high reduced electric field depends almost entirely on the electron's mean free path.

  18. Effects Of Electric Field On Hydrocarbon-Fueled Flames

    Science.gov (United States)

    Yuan, Z.-G.; Hegde, U.

    2003-01-01

    It has been observed that flames are susceptible to electric fields that are much weaker than the breakdown field strength of the flame gases. When an external electric field is imposed on a flame, the ions generated in the flame reaction zone drift in the direction of the electric forces exerted on them. The moving ions collide with the neutral species and change the velocity distribution in the affected region. This is often referred to as ionic wind effect. In addition, the removal of ions from the flame reaction zone can alter the chemical reaction pathway of the flame. On the other hand, the presence of space charges carried by moving ions affects the electric field distribution. As a result, the flame often changes its shape, location and color once an external electric field is applied. The interplay between the flame movement and the change of electric field makes it difficult to determine the flame location for a given configuration of electrodes and fuel source. In normal gravity, the buoyancy-induced flow often complicates the problem and hinders detailed study of the interaction between the flame and the electric field. In this work, the microgravity environment established at the 2.2 Second Drop Tower at the NASA Glenn Research Center is utilized to effectively remove the buoyant acceleration. The interaction between the flame and the electric field is studied in a one-dimensional domain. A specially designed electrode makes flame current measurements possible; thus, the mobility of ions, ion density, and ionic wind effect can be evaluated.

  19. Dependence of optimal spacing on applied field in ungated field emitter arrays

    Directory of Open Access Journals (Sweden)

    J. R. Harris

    2015-08-01

    Full Text Available In ungated field emitter arrays, the field enhancement factor β of each emitter tip is reduced below the value it would have in isolation due to the presence of adjacent emitters, an effect known as shielding or screening. Reducing the distance b between emitters increases the density of emission sites, but also reduces the emission per site, leading to the existence of an optimal spacing that maximizes the array current. Most researchers have identified that this optimal spacing is comparable to the emitter height h, although there is disagreement about the exact optimization. Here, we develop a procedure to determine the dependence of this optimal spacing on the applied electric field. It is shown that the nature of this dependence is governed by the shape of the β(b curve, and that for typical curves, the optimal value of the emitter spacing b decreases as the applied field increases.

  20. Nanoparticle Near-Surface Electric Field

    OpenAIRE

    Chkhartishvili, Levan

    2016-01-01

    Theoretical studies show that surface reconstruction in some crystals involves splitting the surface atomic layer into two—upper and lower—sublayers consisting of atoms with only positive or only negative effective electric charges, respectively. In a macroscopic crystal with an almost infinite surface, the electric field induced by such a surface-dipole is practically totally concentrated between the sublayers. However, when the material is powdered and its particles are of sufficiently smal...

  1. Report on Non-Contact DC Electric Field Sensors

    Energy Technology Data Exchange (ETDEWEB)

    Miles, R; Bond, T; Meyer, G

    2009-06-16

    This document reports on methods used to measure DC electrostatic fields in the range of 100 to 4000 V/m using a non-contact method. The project for which this report is written requires this capability. Non-contact measurements of DC fields is complicated by the effect of the accumulation of random space-charges near the sensors which interfere with the measurement of the field-of-interest and consequently, many forms of field measurements are either limited to AC measurements or use oscillating devices to create pseudo-AC fields. The intent of this document is to report on methods discussed in the literature for non-contact measurement of DC fields. Electric field meters report either the electric field expressed in volts per distance or the voltage measured with respect to a ground reference. Common commercial applications for measuring static (DC) electric fields include measurement of surface charge on materials near electronic equipment to prevent arcing which can destroy sensitive electronic components, measurement of the potential for lightning to strike buildings or other exposed assets, measurement of the electric fields under power lines to investigate potential health risks from exposure to EM fields and measurement of fields emanating from the brain for brain diagnostic purposes. Companies that make electric field sensors include Trek (Medina, NY), MKS Instruments, Boltek, Campbell Systems, Mission Instruments, Monroe Electronics, AlphaLab, Inc. and others. In addition to commercial vendors, there are research activities continuing in the MEMS and optical arenas to make compact devices using the principles applied to the larger commercial sensors.

  2. Anomalous electrostatic potential properties in carbon nanotube thin films under a weak external electric field

    OpenAIRE

    Ishiyama, U; Cuong, Nguyen Thanh; Okada, Susumu

    2016-01-01

    Using density functional theory, we studied the electronic properties of carbon nanotube (CNT) thin films under an electric field. The carrier accumulation due to the electric field depends strongly on the CNT species forming the thin films. Under a low electron concentration, the injected electrons are distributed throughout the CNTs, leading to an unusual electric field between CNTs, the direction of which is opposite to that of the applied field. This unusual field response of CNT thin fil...

  3. Microwave electric field sensing with Rydberg atoms

    Science.gov (United States)

    Stack, Daniel T.; Kunz, Paul D.; Meyer, David H.; Solmeyer, Neal

    2016-05-01

    Atoms form the basis of precise measurement for many quantities (time, acceleration, rotation, magnetic field, etc.). Measurements of microwave frequency electric fields by traditional methods (i.e. engineered antennas) have limited sensitivity and can be difficult to calibrate properly. Highly-excited (Rydberg) neutral atoms have very large electric-dipole moments and many dipole allowed transitions in the range of 1 - 500 GHz. It is possible to sensitively probe the electric field in this range using the combination of two quantum interference phenomena: electromagnetically induced transparency and the Autler-Townes effect. This technique allows for very sensitive field amplitude, polarization, and sub-wavelength imaging measurements. These quantities can be extracted by measuring properties of a probe laser beam as it passes through a warm rubidium vapor cell. Thus far, Rydberg microwave electrometry has relied upon the absorption of the probe laser. We report on our use of polarization rotation, which corresponds to the real part of the susceptibility, for measuring the properties of microwave frequency electric fields. Our simulations show that when a magnetic field is present and directed along the optical propagation direction a polarization rotation signal exists and can be used for microwave electrometry. One central advantage in using the polarization rotation signal rather than the absorption signal is that common mode laser noise is naturally eliminated leading to a potentially dramatic increase in signal-to-noise ratio.

  4. Electric field induced deformation of sessile drops

    Science.gov (United States)

    Corson, Lindsey; Tsakonas, Costas; Duffy, Brian; Mottram, Nigel; Brown, Carl; Wilson, Stephen

    2014-11-01

    The ability to control the shape of a drop with the application of an electric field has been exploited for many technological applications including measuring surface tension, producing an optical display device, and optimising the optical properties of microlenses. In this work we consider, both theoretically and experimentally, the deformation of pinned sessile drops with contact angles close to either 0° or 90° resting on the lower substrate inside a parallel plate capacitor due to an A.C. electric field. Using both asymptotic and numerical approaches we obtain predictive equations for the static and dynamic drop shape deformations as functions of the key experimental parameters (drop size, capacitor plate separation, electric field magnitude and contact angle). The asymptotic results agree well with the experimental results for a range of liquids. We gratefully acknowledge the financial support of EPSRC via research Grants EP/J009865 and EP/J009873.

  5. Fluorescence excitation studies of molecular photoionization in external electric fields

    International Nuclear Information System (INIS)

    Using molecular nitrogen as an example, we show that fluorescence excitation spectroscopy can be used to measure partial photoionization cross sections of free molecules in external electric fields. The production of the N2+(B2Σ/sub u/+) state was studied and the threshold for this process was found to shift linearly with the square root of the applied field. This behavior is compared with the hydrogenic case and with previously studied systems

  6. Polyelectrolytes polarization in non-uniform electric fields

    OpenAIRE

    Farahpour, Farnoush; Varnik, Fathollah; Ejtehadi, Mohammad Reza

    2014-01-01

    Stretching dynamics of polymers in microfluidics is of particular interest for polymer scientists. As a charged polymer, a polyelectrolyte can be deformed from its coiled equilibrium configuration to an extended chain by applying uniform or non-uniform electric fields. By means of hybrid lattice Boltzmann-molecular dynamics simulations, we investigate how the condensed counterions around the polyelectrolyte contribute to the polymer stretching in inhomogeneous fields. As an application, we di...

  7. Temperature/electric field scaling in Ferroelectrics

    Energy Technology Data Exchange (ETDEWEB)

    Hajjaji, Abdelowahed, E-mail: Hajjaji12@gmail.co [Laboratoire de Genie Electrique et Ferroelectricite, LGEF, INSA LYON, Bat. Gustave Ferrie, 69621 Villeurbanne Cedex (France); Guyomar, Daniel; Pruvost, Sebastien [Laboratoire de Genie Electrique et Ferroelectricite, LGEF, INSA LYON, Bat. Gustave Ferrie, 69621 Villeurbanne Cedex (France); Touhtouh, Samira [Laboratoire de Physique de la Matiere Condensee, LPMC, Departement de Physique, Faculte des Sciences, 24000 El-Jadida, Maroc (Morocco); Yuse, Kaori [Laboratoire de Genie Electrique et Ferroelectricite, LGEF, INSA LYON, Bat. Gustave Ferrie, 69621 Villeurbanne Cedex (France); Boughaleb, Yahia [Laboratoire de Physique de la Matiere Condensee, LPMC, Departement de Physique, Faculte des Sciences, 24000 El-Jadida, Maroc (Morocco)

    2010-07-01

    The effects of the field amplitude (E) and temperature on the polarization and their scaling relations were investigated on rhombohedral PMN-xPT ceramics. The scaling law was based on the physical symmetries of the problem and rendered it possible to express the temperature variation ({Delta}{theta}) as an electric field equivalent {Delta}E{sub eq}=({alpha}+2{beta}xP(E,{theta}{sub 0}))x{Delta}{theta}. Consequently, this was also the case for the relationship between the entropy ({Gamma}) and polarization (P). Rhombohedral Pb(Mg{sub 1/3}Nb{sub 2/3}){sub 0.75}Ti{sub 0.25}O{sub 3} ceramics were used for the verification. It was found that such an approach permitted the prediction of the maximal working temperature, using only purely electrical measurements. It indicates that the working temperature should not exceed 333 K. This value corresponds to the temperature maximum before the dramatic decrease of piezoelectric properties. Reciprocally, the polarization behavior under electrical field can be predicted, using only purely thermal measurements. The scaling law enabled a prediction of the piezoelectric properties (for example, d{sub 31}) under an electrical field replacing the temperature variation ({Delta}{theta}) by {Delta}E/({alpha}+2{beta}xp(E,{theta}{sub 0})). Inversely, predictions of the piezoelectric properties (d{sub 31}) as a function of temperature were permitted using purely only electrical measurements.

  8. Microfluidic Screening of Electric Fields for Electroporation

    Science.gov (United States)

    Garcia, Paulo A.; Ge, Zhifei; Moran, Jeffrey L.; Buie, Cullen R.

    2016-02-01

    Electroporation is commonly used to deliver molecules such as drugs, proteins, and/or DNA into cells, but the mechanism remains poorly understood. In this work a rapid microfluidic assay was developed to determine the critical electric field threshold required for inducing bacterial electroporation. The microfluidic device was designed to have a bilaterally converging channel to amplify the electric field to magnitudes sufficient to induce electroporation. The bacterial cells are introduced into the channel in the presence of SYTOX®, which fluorescently labels cells with compromised membranes. Upon delivery of an electric pulse, the cells fluoresce due to transmembrane influx of SYTOX® after disruption of the cell membranes. We calculate the critical electric field by capturing the location within the channel of the increase in fluorescence intensity after electroporation. Bacterial strains with industrial and therapeutic relevance such as Escherichia coli BL21 (3.65 ± 0.09 kV/cm), Corynebacterium glutamicum (5.20 ± 0.20 kV/cm), and Mycobacterium smegmatis (5.56 ± 0.08 kV/cm) have been successfully characterized. Determining the critical electric field for electroporation facilitates the development of electroporation protocols that minimize Joule heating and maximize cell viability. This assay will ultimately enable the genetic transformation of bacteria and archaea considered intractable and difficult-to-transfect, while facilitating fundamental genetic studies on numerous diverse microbes.

  9. Dependence of electric field on STM tip preparation

    DEFF Research Database (Denmark)

    Huang, D.H.; Grey, Francois; Aono, M.

    1998-01-01

    Voltage pulses applied between an STM tip and a surface can modify the surface on the nanometer scale due to electric-field-induced evaporation. However, at present, different groups have achieved surface modification with quite different bias conditions, and it is still difficult to obtain high...... reproducibility in such experiments. In this paper, we measure the tip displacement during a pulse at constant tunnelling current, and deduce that the electric field produced by the pulse depends in a systematic way on tip preparation, The results show how differences in tip preparation can be a major source...

  10. Uniform electric field induced lateral migration of a sedimenting drop

    CERN Document Server

    Bandopadhyay, Aditya; Chakraborty, Suman

    2015-01-01

    We investigate the motion of a sedimenting spherical drop in the presence of an applied uniform electric field in an otherwise arbitrary direction in the limit of low surface charge convection. We analytically solve the electric potential in and around the leaky dielectric drop, and solve for the Stokesian velocity and pressure fields. We obtain the drop velocity through perturbations in powers of the electric Reynolds number which signifies the importance of the charge relaxation time scale as compared to the convective time scale. We show that in the presence of electric field either in the sedimenting direction or orthogonal to it, there is a change in the drop velocity only in the direction of sedimentation due to an asymmetric charge distribution in the same direction. However, in the presence of an electric field applied in both the directions, and depending on the permittivities and conductivities of the two fluids, we obtain a non-intuitive lateral migration of drop in addition to the buoyancy driven ...

  11. Electric Field Quantitative Measurement System and Method

    Science.gov (United States)

    Generazio, Edward R. (Inventor)

    2016-01-01

    A method and system are provided for making a quantitative measurement of an electric field. A plurality of antennas separated from one another by known distances are arrayed in a region that extends in at least one dimension. A voltage difference between at least one selected pair of antennas is measured. Each voltage difference is divided by the known distance associated with the selected pair of antennas corresponding thereto to generate a resulting quantity. The plurality of resulting quantities defined over the region quantitatively describe an electric field therein.

  12. Electric field stimulated growth of Zn whiskers

    Science.gov (United States)

    Niraula, D.; McCulloch, J.; Warrell, G. R.; Irving, R.; Karpov, V. G.; Shvydka, Diana

    2016-07-01

    We have investigated the impact of strong (˜104 V/cm) electric fields on the development of Zn whiskers. The original samples, with considerable whisker infestation were cut from Zn-coated steel floors and then exposed to electric fields stresses for 10-20 hours at room temperature. We used various electric field sources, from charges accumulated in samples irradiated by: (1) the electron beam of a scanning electron microscope (SEM), (2) the electron beam of a medical linear accelerator, and (3) the ion beam of a linear accelerator; we also used (4) the electric field produced by a Van der Graaf generator. In all cases, the exposed samples exhibited a considerable (tens of percent) increase in whiskers concentration compared to the control sample. The acceleration factor defined as the ratio of the measured whisker growth rate over that in zero field, was estimated to approach several hundred. The statistics of lengths of e-beam induced whiskers was found to follow the log-normal distribution known previously for metal whiskers. The observed accelerated whisker growth is attributed to electrostatic effects. These results offer promise for establishing whisker-related accelerated life testing protocols.

  13. Particle creation by peak electric field

    CERN Document Server

    Adorno, T C; Gitman, D M

    2016-01-01

    The particle creation by the so-called peak electric field is considered. The latter field is a combination of two exponential parts, one exponentially-increasing and another exponentially-decreasing. We find exact solutions of the Dirac equation with the field under consideration with appropriate asymptotic conditions and calculate all the characteristics of particle creation effect, in particular, differential mean numbers of created particle, total number of created particles, and the probability for a vacuum to remain a vacuum. Characteristic asymptotic regimes are discussed in detail and a comparison with the pure asymptotically decaying field is considered.

  14. Carbon nanotube based separation columns for high electrical field strengths in microchip electrochromatography

    DEFF Research Database (Denmark)

    Mogensen, Klaus Bo; Chen, Miaoxiang Max; Mølhave, Kristian;

    2011-01-01

    Patterning carbon nanotubes into an array of pillars makes it possible to increase the electrical field strength applied across a separation column by more than one order of magnitude.......Patterning carbon nanotubes into an array of pillars makes it possible to increase the electrical field strength applied across a separation column by more than one order of magnitude....

  15. Interaction of electric and hydrodynamic fields

    Energy Technology Data Exchange (ETDEWEB)

    Ostroumov, G.A.

    1979-01-01

    A systematic presentation is made of the basic electrophysical and hydromechanical characteristics that are responsible for the processes of heat and mass exchange in insulating fluids that are found in strong electric fields. Recommendations are made with respect to the intensification of these processes as well as to their use in science and technology. Promising topics for future research are indicated. The introduction lists two ways that lead to the elaboration of two concepts that are essential to electrohydrodynamics - electrochemical and electro-power engineering. The first four chapters deal with a study of pondermotive forces in immobile media. The fifth chapter presents experimental material on electric wind in gases. Information is also given on electric wind in fluids and a theoretical interpretation of this phenomenon, and on results of experimental and theoretical studies of electric breakdown of fluids. 200 references, 108 figures, 12 tables.

  16. Health of workers exposed to electric fields.

    Science.gov (United States)

    Broadbent, D E; Broadbent, M H; Male, J C; Jones, M R

    1985-02-01

    The results of health questionnaire interviews with 390 electrical power transmission and distribution workers, together with long term estimates of their exposure to 50 Hz electric fields, and short term measurements of the actual exposure for 287 of them are reported. Twenty eight workers received measurable exposures, averaging about 30 kVm-1h over the two week measurement period. Estimated exposure rates were considerably greater, but showed fair correlation with the measurements. Although the general level of health was higher than we have found in manual workers in other industries, there were significant differences in the health measures between different categories of job, different parts of the country, and in association with factors such as overtime, working alone, or frequently changing shift. After allowing for the effects of job and location, however, we found no significant correlations of health with either measured or estimated exposure to electric fields. PMID:3970875

  17. Motional Spin Relaxation in Large Electric Fields

    CERN Document Server

    Schmid, Riccardo; Filippone, B W

    2008-01-01

    We discuss the precession of spin-polarized Ultra Cold Neutrons (UCN) and $^{3}\\mathrm{He}$ atoms in uniform and static magnetic and electric fields and calculate the spin relaxation effects from motional $v\\times E$ magnetic fields. Particle motion in an electric field creates a motional $v\\times E$ magnetic field, which when combined with collisions, produces variations of the total magnetic field and results in spin relaxation of neutron and $^{3}\\mathrm{He}$ samples. The spin relaxation times $T_{1}$ (longitudinal) and $T_{2}$ (transverse) of spin-polarized UCN and $^{3}\\mathrm{He}$ atoms are important considerations in a new search for the neutron Electric Dipole Moment at the SNS \\emph{nEDM} experiment. We use a Monte Carlo approach to simulate the relaxation of spins due to the motional $v\\times E$ field for UCN and for $^{3}\\mathrm{He}$ atoms at temperatures below $600 \\mathrm{mK}$. We find the relaxation times for the neutron due to the $v\\times E$ effect to be long compared to the neutron lifetime, ...

  18. Vacuum interface flashover with bipolar electric fields

    Energy Technology Data Exchange (ETDEWEB)

    Tucker, W.K.; Anderson, R.A.; Hasti, D.E.; Jones, E.E.; Bennett, L.F.

    1985-05-01

    High energy, compact, particle accelerators require accelerating cavities that have large gradients and operate with high efficiency. The bipolar electric fields required in these efficient accelerating cavities place severe requirements on the vacuum interface. Experimentally, we have found that the bipolar flashover field varies as t/sup -1/2/ for times out to 300 ns and then remains essentially constant at 33 kV/cm for longer duration waveforms, whereas materials subjected to unipolar electric fields follow a t/sup -1/6/ relationship. Furthermore, specific accelerating cavities offer enhancements that may be employed to achieve highly uniform electric fields across the vacuum interface. Using these results and the results of a previously developed theory of unipolar flashover, a new interface has been designed and 50 kV/cm bipolar flashover field achieved for a waveform train that lasted 1 ..mu..s. This paper will discuss the design of this vacuum interface and the evaluation of various materials that led to achieving bipolar flashover fields 50% greater than we had previously obtained for long duration waveforms. 10 refs., 6 figs.

  19. Vacuum interface flashover with bipolar electric fields

    International Nuclear Information System (INIS)

    High energy, compact, particle accelerators require accelerating cavities that have large gradients and operate with high efficiency. The bipolar electric fields required in these efficient accelerating cavities place severe requirements on the vacuum interface. Experimentally, we have found that the bipolar flashover field varies as t/sup -1/2/ for times out to 300 ns and then remains essentially constant at 33 kV/cm for longer duration waveforms, whereas materials subjected to unipolar electric fields follow a t/sup -1/6/ relationship. Furthermore, specific accelerating cavities offer enhancements that may be employed to achieve highly uniform electric fields across the vacuum interface. Using these results and the results of a previously developed theory of unipolar flashover, a new interface has been designed and 50 kV/cm bipolar flashover field achieved for a waveform train that lasted 1 μs. This paper will discuss the design of this vacuum interface and the evaluation of various materials that led to achieving bipolar flashover fields 50% greater than we had previously obtained for long duration waveforms. 10 refs., 6 figs

  20. Pulsed Electric Field treatment of packaged food

    NARCIS (Netherlands)

    Roodenburg, B.

    2011-01-01

    Food manufacturers are looking for new preservation techniques that don’t influence the fresh-like characteristics of products. Non-thermal pasteurisation of food with Pulsed Electric Fields (often referred to as PEF) is an emerging technology, where the change of the food is less than with thermal

  1. Plasma instabilities in high electric fields

    DEFF Research Database (Denmark)

    Morawetz, K.; Jauho, Antti-Pekka

    1994-01-01

    expression is derived for the nonequilibrium dielectric function epsilon(K, omega). For certain values of momenta K and frequency omega, Imepsilon(K, omega) becomes negative, implying a plasma instability. This new instability exists only for strong electric fields, underlining its nonequilibrium origin....

  2. Modelling electricity forward markets by ambit fields

    DEFF Research Database (Denmark)

    Barndorff-Nielsen, Ole; Fred Espen Benth, Fred Espen; Veraart, Almut

    This paper proposes a new modelling framework for electricity forward markets, which is based on ambit fields. The new model can capture many of the stylised facts observed in energy markets. One of the main differences to the traditional models lies in the fact that we do not model the dynamics...

  3. Field-aligned currents and ionospheric electric fields

    Science.gov (United States)

    Yasuhara, F.; Akasofu, S.-I.

    1977-01-01

    It is shown that the observed distribution of the ionospheric electric field can be deduced from an equation combining Ohm's law with the current continuity equation by using the 'observed' distribution of field-aligned currents as the boundary condition for two models of the ionosphere. The first model has one conductive annular ring representing the quiet-time auroral precipitation belt; the second has two conductive annular rings that simulate the discrete and diffuse auroral regions. An analysis is performed to determine how well the electric-field distribution can be reproduced. The results indicate that the first model reproduces the Sq(p)-type distribution, the second model reproduces reasonably well a substorm-type potential and ionospheric current patterns together with the Harang discontinuity, and that the distribution of field-aligned currents is the same for both models.

  4. Vacuum interface flashover with bipolar electric fields

    International Nuclear Information System (INIS)

    High energy, compact, particle accelerators require accelerating cavities that have large gradients and operate with high efficiency. The bipolar electric fields necessary in these efficient accelerating cavities place severe requirements on the insulator-vacuum interface. A new interface has been designed and 50 gv/cm bipolar flashover field achieved for a waveform train that lasted 1 μs. This paper discusses the design of this vacuum interface and the evaluation of various materials that led to achieving bipolar flashover fields 50% greater than the authors had previously obtained

  5. Tikekar superdense stars in electric fields

    Science.gov (United States)

    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.

  6. Fractional calculus model of electrical impedance applied to human skin.

    Science.gov (United States)

    Vosika, Zoran B; Lazovic, Goran M; Misevic, Gradimir N; Simic-Krstic, Jovana B

    2013-01-01

    Fractional calculus is a mathematical approach dealing with derivatives and integrals of arbitrary and complex orders. Therefore, it adds a new dimension to understand and describe basic nature and behavior of complex systems in an improved way. Here we use the fractional calculus for modeling electrical properties of biological systems. We derived a new class of generalized models for electrical impedance and applied them to human skin by experimental data fitting. The primary model introduces new generalizations of: 1) Weyl fractional derivative operator, 2) Cole equation, and 3) Constant Phase Element (CPE). These generalizations were described by the novel equation which presented parameter [Formula: see text] related to remnant memory and corrected four essential parameters [Formula: see text] We further generalized single generalized element by introducing specific partial sum of Maclaurin series determined by parameters [Formula: see text] We defined individual primary model elements and their serial combination models by the appropriate equations and electrical schemes. Cole equation is a special case of our generalized class of models for[Formula: see text] Previous bioimpedance data analyses of living systems using basic Cole and serial Cole models show significant imprecisions. Our new class of models considerably improves the quality of fitting, evaluated by mean square errors, for bioimpedance data obtained from human skin. Our models with new parameters presented in specific partial sum of Maclaurin series also extend representation, understanding and description of complex systems electrical properties in terms of remnant memory effects. PMID:23577065

  7. Fractional calculus model of electrical impedance applied to human skin.

    Directory of Open Access Journals (Sweden)

    Zoran B Vosika

    Full Text Available Fractional calculus is a mathematical approach dealing with derivatives and integrals of arbitrary and complex orders. Therefore, it adds a new dimension to understand and describe basic nature and behavior of complex systems in an improved way. Here we use the fractional calculus for modeling electrical properties of biological systems. We derived a new class of generalized models for electrical impedance and applied them to human skin by experimental data fitting. The primary model introduces new generalizations of: 1 Weyl fractional derivative operator, 2 Cole equation, and 3 Constant Phase Element (CPE. These generalizations were described by the novel equation which presented parameter [Formula: see text] related to remnant memory and corrected four essential parameters [Formula: see text] We further generalized single generalized element by introducing specific partial sum of Maclaurin series determined by parameters [Formula: see text] We defined individual primary model elements and their serial combination models by the appropriate equations and electrical schemes. Cole equation is a special case of our generalized class of models for[Formula: see text] Previous bioimpedance data analyses of living systems using basic Cole and serial Cole models show significant imprecisions. Our new class of models considerably improves the quality of fitting, evaluated by mean square errors, for bioimpedance data obtained from human skin. Our models with new parameters presented in specific partial sum of Maclaurin series also extend representation, understanding and description of complex systems electrical properties in terms of remnant memory effects.

  8. Influence of electric field on cellular migration

    Science.gov (United States)

    Guido, Isabella; Bodenschatz, Eberhard

    Cells have the ability to detect continuous current electric fields (EFs) and respond to them with a directed migratory movement. Dictyostelium discoideum (D.d.) cells, a key model organism for the study of eukaryotic chemotaxis, orient and migrate toward the cathode under the influence of an EF. The underlying sensing mechanism and whether it is shared by the chemotactic response pathway remains unknown. Whereas genes and proteins that mediate the electric sensing as well as that define the migration direction have been previously investigated in D.d. cells, a deeper knowledge about the cellular kinematic effects caused by the EF is still lacking. Here we show that besides triggering a directional bias the electric field influences the cellular kinematics by accelerating the movement of cells along their path. We found that the migratory velocity of the cells in an EF increases linearly with the exposure time. Through the analysis of the PI3K and Phg2 distribution in the cytosol and of the cellular adherence to the substrate we aim at elucidating whereas this speed up effect in the electric field is due to either a molecular signalling or the interaction with the substrate. This work is part of the MaxSynBio Consortium which is jointly funded by the Federal Ministry of Education and Research of Germany and the Max Planck Society.

  9. Effect of Low Electric Fields on Alpha Scintillation Light Yield in Liquid Argon

    CERN Document Server

    Agnes, P; Alexander, T; Alton, A K; Asner, D M; Back, H O; Baldin, B; Biery, K; Bocci, V; Bonfini, G; Bonivento, W; Bossa, M; Bottino, B; Brigatti, A; Brodsky, J; Budano, F; Bussino, S; Cadeddu, M; Cadoni, M; Calaprice, F; Canci, N; Candela, A; Caravati, M; Cariello, M; Carlini, M; Catalanotti, S; Cavalcante, P; Chepurnov, A; Cicalò, C; Cocco, A G; Covone, G; D'Angelo, D; D'Incecco, M; Davini, S; De Cecco, S; De Deo, M; De Vincenzi, M; Derbin, A; Devoto, A; Di Eusanio, F; Di Pietro, G; Dionisi, C; Edkins, E; Empl, A; Fan, A; Fiorillo, G; Fomenko, K; Forster, G; Franco, D; Gabriele, F; Galbiati, C; Giagu, S; Giganti, C; Giovanetti, G K; Goretti, A M; Granato, F; Gromov, M; Guan, M; Guardincerri, Y; Hackett, B R; Herner, K; Hughes, D; Humble, P; Hungerford, E V; Ianni, A; James, I; Johnson, T N; Jollet, C; Keeter, K; Kendziora, C L; Koh, G; Korablev, D; Korga, G; Kubankin, A; Li, X; Lissia, M; Loer, B; Lombardi, P; Longo, G; Ma, Y; Machulin, I N; Mandarano, A; Mari, S M; Maricic, J; Marini, L; Martoff, C J; Meregaglia, A; Meyers, P D; Milincic, R; Miller, J D; Montanari, D; Monte, A; Mount, B J; Muratova, V N; Musico, P; Napolitano, J; Agasson, A Navrer; Odrowski, S; Oleinik, A; Orsini, M; Ortica, F; Pagani, L; Pallavicini, M; Pantic, E; Parmeggiano, S; Pelczar, K; Pelliccia, N; Pocar, A; Pordes, S; Pugachev, D A; Qian, H; Randle, K; Ranucci, G; Razeti, M; Razeto, A; Reinhold, B; Renshaw, A L; Rescigno, M; Riffard, Q; Romani, A; Rossi, B; Rossi, N; Rountree, D; Sablone, D; Saggese, P; Sands, W; Savarese, C; Schlitzer, B; Segreto, E; Semenov, D A; Shields, E; Singh, P N; Skorokhvatov, M D; Smirnov, O; Sotnikov, A; Stanford, C; Suvorov, Y; Tartaglia, R; Tatarowicz, J; Testera, G; Tonazzo, A; Trinchese, P; Unzhakov, E V; Verducci, M; Vishneva, A; Vogelaar, B; Wada, M; Walker, S; Wang, H; Wang, Y; Watson, A W; Westerdale, S; Wilhelmi, J; Wojcik, M M; Xiang, X; Xiao, X; Xu, J; Yang, C; Zhong, W; Zhu, C; Zuzel, G

    2016-01-01

    Measurements were made of scintillation light yield of alpha particles from the $^{222}$Rn decay chain within the DarkSide-50 liquid argon time projection chamber. The light yield was found to increase as the applied electric field increased, with alphas in a 200 V/cm electric field exhibiting a $\\sim$2% increase in light yield compared to alphas in no field.

  10. Transport and radial electric field in torus plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Okamoto, Masao; Nakajima, Noriyoshi; Sugama, Hideo [National Inst. for Fusion Science, Toki, Gifu (Japan); Maluckov, Aleksandra A. [University of Nis, Prirodno-Matematicki Fakultet, FR (Yugoslavia); Satake, Shinsuke [Graduate University for Advanced Studies, Hayama, Kanagawa (Japan)

    2002-12-01

    Transport phenomena in torus plasmas are discussed focusing on the generation of the neoclassical radial electric field. A sophisticated {delta}f Monte Carlo particle simulation code 'FORTEC' is developed including the effect of finite orbit width (FOW), which is the non-local property of the plasma transport. It will be shown that the neoclassical radial electric field in the axisymmetric tokamak is generated due to this FOW effect. The Lagrangian approach is applied to construct a non-local transport theory in the region of near-axis. The reduction of the heat diffusivity toward the axis will be shown. From a statistical point of view, diffusion processes are studied in the presence of irregular magnetic fields. It is shown that the diffusion processes are non-local in almost all the cases if there are some irregularities in the magnetic field. (author)

  11. Lightning Location Using Electric Field Change Meters

    Science.gov (United States)

    Bitzer, P. M.; Christian, H.; Burchfield, J.

    2010-12-01

    Briefly introduced last year, the Huntsville Alabama Field Change Array (HAFCA) is a collection of electric field change meters deployed in and around Huntsville. Armed with accurate GPS timing, the array is able to sample electric field changes due to lightning strokes simultaneously at several locations. For the first time, different components of the lightning flash can be located in three dimensions using only electric field change records. In particular, this research will show spacetime locations throughout entire lightning strokes, from preliminary breakdown pulses to the return stroke and later processes that may be related to charge neutralization. To find the spacetime locations, standard time of arrival methods will be used: finding the parameters that best fit the model using the Marquardt method. However, we will also discuss using Markov Chain Monte Carlo methods which yield a better estimation of errors. With this information, we will discuss selected cases from the array to date. In particular, we will discuss the inter-comparison of HAFCA with two other well known lightning location arrays, NLDN and NALMA. Specifically, we will explore the relationship between the first LMA pulse in a lightning stroke and the locations of preliminary breakdown pulses and the implications on lightning initiation. Further, the return stroke locations will be shown to agree reasonably well with NLDN locations. We will also locate compact intracloud discharges (CIDs) and compare with NLDN locations.

  12. Self-consistent stationary MHD shear flows in the solar atmosphere as electric field generators

    CERN Document Server

    Nickeler, D H; Wiegelmann, T; Kraus, M

    2014-01-01

    Magnetic fields and flows in coronal structures, for example, in gradual phases in flares, can be described by 2D and 3D magnetohydrostatic (MHS) and steady magnetohydrodynamic (MHD) equilibria. Within a physically simplified, but exact mathematical model, we study the electric currents and corresponding electric fields generated by shear flows. Starting from exact and analytically calculated magnetic potential fields, we solveid the nonlinear MHD equations self-consistently. By applying a magnetic shear flow and assuming a nonideal MHD environment, we calculated an electric field via Faraday's law. The formal solution for the electromagnetic field allowed us to compute an expression of an effective resistivity similar to the collisionless Speiser resistivity. We find that the electric field can be highly spatially structured, or in other words, filamented. The electric field component parallel to the magnetic field is the dominant component and is high where the resistivity has a maximum. The electric field ...

  13. The manipulation of magnetic coercive field and orientation of magnetic anisotropy via electric fields

    Science.gov (United States)

    Xiang, Jun-Sen; Ye, Jun; Yang, Yun-Long; Xie, Yong; Li, Wei; Chen, Zi-Yu

    2016-08-01

    We report the effects of the electric field on the magnetic coercive field (H c) and uniaxial magnetic anisotropy (UMA) orientation of polycrystalline Ni film grown on an unpoled (0 1 1) [Pb(Mg1/3Nb2/3)O3](1‑x)–[PbTiO3] x (PMN-PT) single crystal substrate. Under various electric fields, normalized magnetic hysteresis loops of Ni films change in width; this represents the change of coercive field (ΔH c). Loop shapes are found to depend on the angle between the magnetic field and the sample, where changes in the shape reveal a small rotation of UMA. All these changes show that the magnetic properties vary periodically with a periodic electric field, by strain-mediated magnetoelectric coupling in the Ni/Ag/PMN-PT/Ag heterostructure. The poled PMN-PT produces strains under electric fields in the range of  ‑4.2 kV cm‑1  ⩽  E  ⩽  4.2 kV cm‑1, then transfers it to Ni films resulting in changes to its H c and UMA. The curves of the in-plane H c and strain, at two mutually orthogonal directions, represent butterfly patterns versus the applied electric field. In addition, the changes observed in both the H c and strain show asymmetric features in two orthogonal directions, which results in a small rotation angle of the UMA of Ni as the electric field decreases. The effective manipulation of magnitude and orientation of magnetic anisotropy via electric fields in ferromagnetic/ferroelectric (FM/FE) heterostructures is an important step towards controlling the magnetic tunnel junctions.

  14. Electric field tuning of phase separation in manganite thin films

    KAUST Repository

    Lourembam, James

    2014-01-29

    In this paper, we investigate the electric field effect on epitaxial Pr0.65(Ca0.75Sr0.25)0.35MnO3 thin films in electric double-layer transistors. Different from the conventional transistors with semiconducting channels, the sub(micrometer)-scale phase separation in the manganite channels is expected to result in inhomogeneous distribution of mobile carriers and local enhancement of electric field. The field effect is much larger in the low-temperature phase separation region compared to that in the high-temperature polaron transport region. Further enhancement of electroresistance is achieved by applying a magnetic field, and a 250% modulation of resistance is observed at 80 K, equivalent to an increase of the ferromagnetic metallic phase fraction by 0.51%, as estimated by the general effective medium model. Our results illustrate the complementary nature of electric and magnetic field effects in phase-separated manganites, providing insights on such novel electronic devices based on complex oxides.

  15. Ex vivo and in silico feasibility study of monitoring electric field distribution in tissue during electroporation based treatments

    OpenAIRE

    Kranjc, Matej; Bajd, Franci; Serša, Igor; Woo, Eung Je; Miklavčič, Damijan

    2015-01-01

    Magnetic resonance electrical impedance tomography (MREIT) was recently proposed for determining electric field distribution during electroporation in which cell membrane permeability is temporary increased by application of an external high electric field. The method was already successfully applied for reconstruction of electric field distribution in agar phantoms. Before the next step towards in vivo experiments is taken, monitoring of electric field distribution during electroporation of ...

  16. On-demand hierarchical patterning with electric fields

    OpenAIRE

    Wang, Qiming; Robinson, Dominick; Zhao, Xuanhe

    2014-01-01

    We report a method to generate hierarchical topographical patterns on demand under the control of applied voltages. The method is implemented by harnessing the electro-creasing instability in multilayer elastomer films. The critical electric field for electro-creasing instability in a layer of elastomer scales with square root of the elastomer's modulus, while the wavelength of instability pattern scales with the layer's thickness. By rationally designing elastomer films wit...

  17. Gas storage and separation by electric field swing adsorption

    Science.gov (United States)

    Currier, Robert P; Obrey, Stephen J; Devlin, David J; Sansinena, Jose Maria

    2013-05-28

    Gases are stored, separated, and/or concentrated. An electric field is applied across a porous dielectric adsorbent material. A gas component from a gas mixture may be selectively separated inside the energized dielectric. Gas is stored in the energized dielectric for as long as the dielectric is energized. The energized dielectric selectively separates, or concentrates, a gas component of the gas mixture. When the potential is removed, gas from inside the dielectric is released.

  18. Anisotropic donor states in electric field

    Energy Technology Data Exchange (ETDEWEB)

    Zakrzewski, Adam J. [Institute of Physics, Polish Academy of Sciences, Warsaw (Poland)

    2009-06-15

    In this paper we consider the application of the stabilization method to calculations of the ground state energy and resonance width of shallow donors in a uniform electric field. We show for the first time that within our formulation of this method it is very easy to include various factors influencing electronic structure of shallow impurities, like effective mass anisotropy or magnetic field. We demonstrate that the effective mass anisotropy significantly changes the lifetime of donor bound electrons. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  19. Investigation of electric field distribution on FAC-IR-300 ionization chamber

    Science.gov (United States)

    Mohammadi, S. M.; Tavakoli-Anbaran, H.; Zeinali, H. Z.

    2016-07-01

    One of the important parameters for establishing charge particle equilibrium (CPE) conditions of free-air ionization chamber is an electric field distribution. In this paper, electric field distribution inside the ionization chamber was investigated by finite element method. For this purpose, the effects of adding guard plate and guard strips on the electric field distribution in the ionization chamber were studied. it is necessary to apply a lead box around the ionization chamber body to avoid of scattered radiation effects on the ionization chamber operation, but the lead box changes the electric field distribution. In the following, the effect of lead box on the electric field distribution was studied. Finally, electric field distribution factor (kfield) was calculated by the simulation. The results of the simulation showed that presence of the guard plate and guard strips, and applying a suitable potential to lead box, a convergence of kfield to 1 was achieved.

  20. Spin generation by strong inhomogeneous electric fields

    Science.gov (United States)

    Finkler, Ilya; Engel, Hans-Andreas; Rashba, Emmanuel; Halperin, Bertrand

    2007-03-01

    Motivated by recent experiments [1], we propose a model with extrinsic spin-orbit interaction, where an inhomogeneous electric field E in the x-y plane can give rise, through nonlinear effects, to a spin polarization with non-zero sz, away from the sample boundaries. The field E induces a spin current js^z= z x(αjc+βE), where jc=σE is the charge current, and the two terms represent,respectively, the skew scattering and side-jump contributions. [2]. The coefficients α and β are assumed to be E- independent, but conductivity σ is field dependent. We find the spin density sz by solving the equation for spin diffusion and relaxation with a source term ∇.js^z. For sufficiently low fields, jc is linear in E, and the source term vanishes, implying that sz=0 away from the edges. However, for large fields, σ varies with E. Solving the diffusion equation in a T-shaped geometry, where the electric current propagates along the main channel, we find spin accumulation near the entrance of the side channel, similar to experimental findings [1]. Also, we present a toy model where spin accumulation away from the boundary results from a nonlinear and anisotropic conductivity. [1] V. Sih, et al, Phys. Rev. Lett. 97, 096605 (2006). [2] H.-A. Engel, B.I. Halperin, E.I.Rashba, Phys. Rev. Lett. 95, 166605 (2005).

  1. Radiated Electric Field Calculation of Impulse Radiating Antenna Applying Image Method%用镜像法计算冲击脉冲辐射天线辐射电场

    Institute of Scientific and Technical Information of China (English)

    王赟; 陈永光; 王庆国; 范丽思

    2012-01-01

    In order to conveniently calculate the electric radiation field of impulse radiation antenna with parabolic reflector, an analytical expression of the radiation in time domain was obtained. The expression was derived by using mirror image method based on the field expression of arbitrary wire antennas obtained by the tensor method. An ultra-wideband {UWB) electromagnetic pulse experiment system was built for the purpose of verification. The system used transverse electromagnetic (TEM) horn antenna to measure the radiation field generated by impulse radiation antenna(IRA). The tested results were compared with the radiation field in calculated time domain. It is found that the analytically calculated field waveforms are in good agreement with the experiment results, the peakto-peak error is less than 1 V, and the rise-time error is not more than 5 ps. Consequenly the validity of analytical calculation is proved.%为方便地计算抛物面冲击脉冲辐射天线的辐射电场,根据由张量法得到的任意的线天线电场计算公式,利用镜像法推导得到了冲击脉冲辐射天线辐射电场的时域解析表达式;搭建了超宽带电磁脉冲实验系统,由横电磁波喇叭天线测试场设备测试抛物反射面超宽带辐射天线产生的辐射场;应用解析表达式计算了该实验系统的时域辐射场,并与实验测试结果进行了比较。结果表明解析计算得到的辐射场波形与测试结果能够较好地符合,峰峰值相差〈1V,上升时间相差≤5ps,说明了解析计算的正确性。

  2. Electrical Resistivity of an Elasmobranch's Ampullary Jelly in Varying Electric and Magnetic Fields

    Science.gov (United States)

    Brown, Brandon; Hughes, Mary E.

    2001-03-01

    The ampullae of Lorenzini are believed to function as the electroreceptive organs in elasmobranch fishes. Though the entire excised organs have been the subject of electrical transport measurements, the jelly that fills the ampullae -- composed primarily of glycoproteins with proteins and dissolved salts -- has received less scrutiny. The specific electromagnetic properties of the jelly contribute to electroreception, and we hope to supply useful parameters to modeling efforts via precise electrical characterization. We report preliminary resistivity measurements from ampullary jelly removed, post mortem, from an adult triaenodon obesus (white-tip reef shark). We present data over a broad range of applied electrical currents. We also present data of the resistivity as a function of applied magnetic field strength.

  3. Electric field driven fractal growth dynamics in polymeric medium

    Energy Technology Data Exchange (ETDEWEB)

    Dawar, Anit; Chandra, Amita, E-mail: achandra@physics.du.ac.in

    2014-08-14

    This paper reports the extension of earlier work (Dawar and Chandra, 2012) [27] by including the influence of low values of electric field on diffusion limited aggregation (DLA) patterns in polymer electrolyte composites. Subsequently, specified cut-off value of voltage has been determined. Below the cut-off voltage, the growth becomes direction independent (i.e., random) and gives rise to ramified DLA patterns while above the cut-off, growth is governed by diffusion, convection and migration. These three terms (i.e., diffusion, convection and migration) lead to structural transition that varies from dense branched morphology (DBM) to chain-like growth to dendritic growth, i.e., from high field region (A) to constant field region (B) to low field region (C), respectively. The paper further explores the growth under different kinds of electrode geometries (circular and square electrode geometry). A qualitative explanation for fractal growth phenomena at applied voltage based on Nernst–Planck equation has been proposed. - Highlights: • The paper is an extension of earlier work [Phys. Lett. A 376 (2012) 3604] on effect of electric field on DLA. • Threshold value of electric field has been determined. • Below the threshold, growth is random. • Above the threshold, the growth is governed by diffusion, migration and convection. • Different kinds of electrode geometries have been used to simulate the growth.

  4. Electric-Field-Enhanced Jumping-Droplet Condensation

    Science.gov (United States)

    Miljkovic, Nenad; Preston, Daniel; Enright, Ryan; Limia, Alexander; Wang, Evelyn

    2013-11-01

    When condensed droplets coalesce on a superhydrophobic surface, the resulting droplet can jump due to the conversion of surface energy into kinetic energy. This frequent out-of-plane droplet jumping has the potential to enhance condensation heat and mass transfer. In this work, we demonstrated that these jumping droplets accumulate positive charge that can be used to further increase condensation heat transfer via electric fields. We studied droplet jumping dynamics on silanized nanostructured copper oxide surfaces. By characterizing the droplet trajectories under various applied external electric fields (0 - 50 V/cm), we show that condensation on superhydrophobic surfaces results in a buildup of negative surface charge (OH-) due to dissociated water ion adsorption on the superhydrophobic coating. Consequently, the opposite charge (H3O +) accumulates on the coalesced jumping droplet. Using this knowledge, we demonstrate electric-field-enhanced jumping droplet condensation whereby an external electric field opposes the droplet vapor flow entrainment towards the condensing surface to increase the droplet removal rate and overall surface heat transfer by 100% when compared to state-of-the-art dropwise condensing surfaces. This work not only shows significant condensation heat transfer enhancement through the passive charging of condensed droplets, but promises a low cost approach to increase efficiency for applications such as atmospheric water harvesting and dehumidification.

  5. Experimental study on the effects of AC electric fields on flame spreading over polyethylene-insulated electric-wire

    KAUST Repository

    Jin, Young Kyu

    2010-11-01

    In this present study, we experimentally investigated the effects of electric fields on the characteristics of flames spreading over electric-wires with AC fields. The dependence of the rate at which a flame spreads over polyethylene-insulated wires on the frequency and amplitude of the applied AC electric field was examined. The spreading of the flame can be categorized into linear spreading and non-linearly accelerated spreading of flame. This categorization is based on the axial distribution of the field strength of the applied electric field. The rate at which the flame spreads is highly dependent on the inclined direction of the wire fire. It could be possible to explain the spreading of the flame on the basis of thermal balance. © 2010 The Korean Society of Mechanical Engineers.

  6. Electric Field Induced Surface Modification of Au

    Energy Technology Data Exchange (ETDEWEB)

    Erchak, A.A.; Franklin, G.F.; Houston, J.E.; Mayer, T.M.; Michalske, T.A.

    1999-02-15

    We discuss the role of localized high electric fields in the modification of Au surfaces with a W probe using the Interfacial Force Microscope. Upon bringing a probe close to a Au surface, we measure both the interfacial force and the field emission current as a function of separation with a constant potential of 100 V between tip and sample. The current initially increases exponentially as the separation decreases. However, at a distance of less than {approximately} 500{angstrom} the current rises sharply as the surface begins to distort and rapidly close the gap. Retraction of the tip before contact is made reveals the formation of a mound on the surface. We propose a simple model, in which the localized high electric field under the tip assists the production of mobile Au adatoms by detachment from surface steps, and a radial field gradient causes a net flux of atoms toward the tip by surface diffusion. These processes give rise to an unstable surface deformation which, if left unchecked, results in a destructive mechanical contact. We discuss our findings with respect to earlier work using voltage pulses in the STM as a means of nanofabrication.

  7. Effect of an electric field on an intermittent granular flow

    OpenAIRE

    Mersch, E.; Lumay, G.; F. Boschini; Vandewalle, N.

    2010-01-01

    Granular gravity driven flows of glass beads have been observed in a silo with a flat bottom. A DC high electric field has been applied perpendicularly to the silo to tune the cohesion. The outlet mass flow has been measured. An image subtraction technique has been applied to visualize the flow geometry and a spatiotemporal analysis of the flow dynamics has been performed. The outlet mass flow is independent of voltage, but a transition from funnel flow to rathole flow is observed. This trans...

  8. Electron transport in argon in crossed electric and magnetic fields

    Science.gov (United States)

    Ness; Makabe

    2000-09-01

    An investigation of electron transport in argon in the presence of crossed electric and magnetic fields is carried out over a wide range of values of electric and magnetic field strengths. Values of mean energy, ionization rate, drift velocity, and diffusion tensor are reported here. Two unexpected phenomena arise; for certain values of electric and magnetic field we find regions where the swarm mean energy decreases with increasing electric fields for a fixed magnetic field and regions where swarm mean energy increases with increasing magnetic field for a fixed electric field. PMID:11088933

  9. Electrical Grounding - a Field for Geophysicists and Electrical Engineers Partnership

    Science.gov (United States)

    Freire, P. F.; Pane, E.; Guaraldo, N.

    2012-12-01

    , layered stratified or showing lateral variations, ranging down to several tens of kilometers deep, reaching the crust-mantle interface (typically with the order of 30-40 km). This work aims to analyze the constraints of the current soil models being used for grounding electrodes design, and suggests the need of a soil modeling methodology compatible with large grounding systems. Concerning the aspects related to soil modeling, electrical engineers need to get aware of geophysics resources, such as: - geophysical techniques for soil electrical resistivity prospection (down to about 15 kilometers deep); and - techniques for converting field measured data, from many different geophysical techniques, into adequate soil models for grounding grid simulation. It is also important to equalize the basic knowledge for the professionals that are working together for the specific purpose of soil modeling for electrical grounding studies. The authors have experienced the situation of electrical engineers working with geophysicists, but it was not clear for the latter the effective need of the electrical engineers, and for the engineers it was unknown the available geophysical resources, and also, what to do convert the large amount of soil resistivity data into a reliable soil model.

  10. The induced magnetic and electric fields' paradox leading to multicaloric effects in multiferroics

    Science.gov (United States)

    Vopson, Melvin M.

    2016-04-01

    Magneto-electric effect in multiferroics implies that an applied magnetic field induces an electric polarization change in a multiferroic solid and vice versa, an applied electric field modifies its magnetization. The magneto-electric effect is a powerful feature of multiferroics and has attracted huge interest due to potential technological applications. One such possible application is the multicaloric effect in multiferroics. However, a closer examination of this effect and its derivation leads to a paradox, in which the predicted changes in one of the order phase at a constant applied field are due to the excitation by the same field. Here this apparent paradox is first explained in detail and then solved. Understanding how electric and magnetic fields can be induced in multiferroic materials is an essential tool enabling their theoretical modeling as well as facilitating the introduction of future applications.

  11. Simple circuit to improve electric field homogeneity in contour-clamped homogeneous electric field chambers.

    Science.gov (United States)

    Herrera, José A; Canino, Carlos A; López-Cánovas, Lilia; Gigato, Regnar; Riverón, Ana Maria

    2003-04-01

    We redesigned contour-clamped homogeneous electric field (CHEF) circuitry to eliminate crossover distortion, to set identical potentials at electrodes of each equipotential pair and to drive pairs with transistors in emitter follower stages. An equipotential pair comprised the two electrodes set at the same potential to provide electric field homogeneity inside of the hexagonal array. The new circuitry consisted of two identical circuits, each having a resistor ladder, diodes and transistors. Both circuits were interconnected by diodes that controlled the current flow to electrodes when the array was energized in the 'A' or 'B' direction of the electric field. The total number of transistors was two-thirds of the total number of electrodes. Average voltage deviation from potentials expected at electrodes to achieve a homogeneous electric field was 0.06 V, whereas 0.44 V was obtained with another circuit that used transistors in push-pull stages. The new voltage clamp unit is cheap, generated homogeneous electric field, and gave reproducible and undistorted DNA band patterns. PMID:12707904

  12. Electric fields, weighting fields, signals and charge diffusion in detectors including resistive materials

    CERN Document Server

    AUTHOR|(CDS)2067623

    2016-01-01

    In this report we discuss static and time dependent electric fields in detector geometries with an arbitrary number of parallel layers of a given permittivity and weak conductivity. We derive the Green's functions i.e. the field of a point charge, as well as the weighting fields for readout pads and readout strips in these geometries. The effect of 'bulk' resistivity on electric fields and signals is investigated. The spreading of charge on thin resistive layers is also discussed in detail, and the conditions for allowing the effect to be described by the diffusion equation is discussed. We apply the results to derive fields and induced signals in Resistive Plate Chambers, Micromega detectors including resistive layers for charge spreading and discharge protection as well as detectors using resistive charge division readout like the MicroCAT detector. We also discuss in detail how resistive layers affect signal shapes and increase crosstalk between readout electrodes.

  13. Influence of magnetic field on the electrical breakdown characteristics in cylindrical diode

    International Nuclear Information System (INIS)

    The influence of magnetic field on the electrical breakdown properties is investigated by applying a magnetic field along the longitudinal direction in a cylindrical diode for two electrical polarities. Breakdown characteristics in a crossed magnetic field are analyzed with the equivalentreduced-electric-field concept and Townsend criterion. The discharge experiment at reduced pressure is carried out in the moderate magnetic field. Experimental investigation is concentrated on the magnetic dependent behavior of the electrical breakdown in the lower pressure side of Paschen's minimum. It is found that the electrical breakdown characteristics with respect to the magnetic field depend on electrical polarity of the cylindrical diode, which is interpreted by taking the gyromotion of the individual electrons in the diode into accounts under the moderate magnetic field in the lower pressure side of Paschen's minimum

  14. Stabilization and destabilization effects of the electric field on stochastic precipitate pattern formation

    NARCIS (Netherlands)

    Lagzi, István; Izsák, Ferenc

    2004-01-01

    Stabilization and destabilization effects of an applied electric field on the Liesegang pattern formation in low concentration gradient were studied with numerical model simulations. In the absence of an electric field pattern formation exhibits increasingly stochastic behaviour as the initial conce

  15. Anomalous lattice expansion in yttria stabilized zirconia under simultaneous applied electric and thermal fields: A time-resolved in situ energy dispersive x-ray diffractometry study with an ultrahigh energy synchrotron probe

    Energy Technology Data Exchange (ETDEWEB)

    Akdogan, E. K.; Savkl Latin-Small-Letter-Dotless-I y Latin-Small-Letter-Dotless-I ld Latin-Small-Letter-Dotless-I z, I.; Bicer, H.; Paxton, W.; Toksoy, F.; Tsakalakos, T. [Department of Materials Science and Engineering, Rutgers University, Piscataway, New Jersey 08854-8065 (United States); Zhong, Z. [National Synchrotron Light Source, Brookhaven National Laboratory, Upton, New York 11973 (United States)

    2013-06-21

    Nonisothermal densification in 8% yttria doped zirconia (8YSZ) particulate matter of 250 nm median particle size was studied under 215 V/cm dc electric field and 9 Degree-Sign C/min heating rate, using time-resolved in-situ high temperature energy dispersive x-ray diffractometry with a polychromatic 200 keV synchrotron probe. Densification occurred in the 876-905 Degree-Sign C range, which resulted in 97% of the theoretical density. No local melting at particle-particle contacts was observed in scanning electron micrographs, implying densification was due to solid state mass transport processes. The maximum current draw at 905 Degree-Sign C was 3 A, corresponding to instantaneous absorbed power density of 570 W/cm{sup 3}. Densification of 8YSZ was accompanied by anomalous elastic volume expansions of the unit cell by 0.45% and 2.80% at 847 Degree-Sign C and 905 Degree-Sign C, respectively. The anomalous expansion at 905 Degree-Sign C at which maximum densification was observed is characterized by three stages: (I) linear stage, (II) anomalous stage, and (III) anelastic recovery stage. The densification in stage I (184 s) and II (15 s) was completed in 199 s, while anelastic relaxation in stage III lasted 130 s. The residual strains ({epsilon}) at room temperature, as computed from tetragonal (112) and (211) reflections, are {epsilon}{sub (112)} = 0.05% and {epsilon}{sub (211)} = 0.13%, respectively. Time dependence of (211) and (112) peak widths ({beta}) show a decrease with both exhibiting a singularity at 905 Degree-Sign C. An anisotropy in (112) and (211) peak widths of {l_brace} {beta}{sub (112)}/{beta}{sub (211)}{r_brace} = (3:1) magnitude was observed. No phase transformation occurred at 905 Degree-Sign C as verified from diffraction spectra on both sides of the singularity, i.e., the unit cell symmetry remains tetragonal. We attribute the reduction in densification temperature and time to ultrafast ambipolar diffusion of species arising from the

  16. Radial-Electric-Field Piezoelectric Diaphragm Pumps

    Science.gov (United States)

    Bryant, Robert G.; Working, Dennis C.; Mossi, Karla; Castro, Nicholas D.; Mane, Pooma

    2009-01-01

    In a recently invented class of piezoelectric diaphragm pumps, the electrode patterns on the piezoelectric diaphragms are configured so that the electric fields in the diaphragms have symmetrical radial (along-the-surface) components in addition to through-the-thickness components. Previously, it was accepted in the piezoelectric-transducer art that in order to produce the out-of-plane bending displacement of a diaphragm needed for pumping, one must make the electric field asymmetrical through the thickness, typically by means of electrodes placed on only one side of the piezoelectric material. In the present invention, electrodes are placed on both sides and patterned so as to produce substantial radial as well as through-the-thickness components. Moreover, unlike in the prior art, the electric field can be symmetrical through the thickness. Tests have shown in a given diaphragm that an electrode configuration according to this invention produces more displacement than does a conventional one-sided electrode pattern. The invention admits of numerous variations characterized by various degrees of complexity. Figure 1 is a simplified depiction of a basic version. As in other piezoelectric diaphragm pumps of similar basic design, the prime mover is a piezoelectric diaphragm. Application of a suitable voltage to the electrodes on the diaphragm causes it to undergo out-of-plane bending. The bending displacement pushes a fluid out of, or pulls the fluid into, a chamber bounded partly by the diaphragm. Also as in other diaphragm pumps in general, check valves ensure that the fluid flows only in through one port and only out through another port.

  17. Phosphate vibrations probe local electric fields and hydration in biomolecules

    OpenAIRE

    Nicholas M Levinson; Bolte, Erin E.; Miller, Carrie S.; Corcelli, Steven A.; Boxer, Steven G.

    2011-01-01

    The role of electric fields in important biological processes like binding and catalysis has been studied almost exclusively by computational methods. Experimental measurements of the local electric field in macromolecules are possible using suitably calibrated vibrational probes. Here we demonstrate that the vibrational transitions of phosphate groups are highly sensitive to an electric field and quantify that sensitivity, allowing local electric field measurements to be made in phosphate-co...

  18. Phosphate vibrations probe local electric fields and hydration in biomolecules

    Science.gov (United States)

    Levinson, Nicholas M.; Bolte, Erin E.; Miller, Carrie S.

    2011-01-01

    The role of electric fields in important biological processes like binding and catalysis has been studied almost exclusively by computational methods. Experimental measurements of the local electric field in macromolecules are possible using suitably calibrated vibrational probes. Here we demonstrate that the vibrational transitions of phosphate groups are highly sensitive to an electric field and quantify that sensitivity, allowing local electric field measurements to be made in phosphate-containing biological systems without chemical modification. PMID:21809829

  19. Characterization of composite particles responsive to electric and magnetic fields

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xiaopeng; GUO Hongxia

    2004-01-01

    The multilayer particles with responses to electric and magnetic fields are a prerequisite for particles assembled under external fields. Three routes to produce particles responsive to electric and magnetic fields are presented in this article. The size and morphology, properties as well as the electric-magnetic responses of three kinds of particles are comparatively discussed. This will provide a useful basis for the control of the behavior of the particles in suspensions by external electric and magnetic fields.

  20. AC Electric Field Activated Shape Memory Polymer Composite

    Science.gov (United States)

    Kang, Jin Ho; Siochi, Emilie J.; Penner, Ronald K.; Turner, Travis L.

    2011-01-01

    Shape memory materials have drawn interest for applications like intelligent medical devices, deployable space structures and morphing structures. Compared to other shape memory materials like shape memory alloys (SMAs) or shape memory ceramics (SMCs), shape memory polymers (SMPs) have high elastic deformation that is amenable to tailored of mechanical properties, have lower density, and are easily processed. However, SMPs have low recovery stress and long response times. A new shape memory thermosetting polymer nanocomposite (LaRC-SMPC) was synthesized with conductive fillers to enhance its thermo-mechanical characteristics. A new composition of shape memory thermosetting polymer nanocomposite (LaRC-SMPC) was synthesized with conductive functionalized graphene sheets (FGS) to enhance its thermo-mechanical characteristics. The elastic modulus of LaRC-SMPC is approximately 2.7 GPa at room temperature and 4.3 MPa above its glass transition temperature. Conductive FGSs-doped LaRC-SMPC exhibited higher conductivity compared to pristine LaRC SMP. Applying an electric field at between 0.1 Hz and 1 kHz induced faster heating to activate the LaRC-SMPC s shape memory effect relative to applying DC electric field or AC electric field at frequencies exceeding1 kHz.

  1. Spontaneous electric fields in solid films: spontelectrics

    DEFF Research Database (Denmark)

    Field, David; Plekan, Oksana; Cassidy, Andrew;

    2013-01-01

    When dipolar gases are condensed at sufficiently low temperature onto a solid surface, they form films that may spontaneously exhibit electric fields in excess of 108V/m. This effect, called the ‘spontelectric effect’, was recently revealed using an instrument designed to measure scattering...... and capture of low energy electrons by molecular films. In this review it is described how this discovery was made and the properties of materials that display the spontelectric effect, so-called ‘spontelectrics’, are set out. A discussion is included of properties that differentiate spontelectrics from...

  2. Electrostatic air filters generated by electric fields

    International Nuclear Information System (INIS)

    This paper presents theoretical and experimental findings on fibrous filters converted to electrostatic operation by a nonionizing electric field. Compared to a conventional fibrous filter, the electrostatic filter has a higher efficiency and a longer, useful life. The increased efficiency is attributed to a time independent attraction between polarized fibers and charged, polarized particles and a time dependent attraction between charged fibers and charged, polarized particles. The charge on the fibers results from a dynamic process of charge accumulation due to the particle deposits and a charge dissipation due to the fiber conductivity

  3. Perturbative renormalization of the electric field correlator

    CERN Document Server

    Christensen, C

    2016-01-01

    The momentum diffusion coefficient of a heavy quark in a hot QCD plasma can be extracted as a transport coefficient related to the correlator of two colour-electric fields dressing a Polyakov loop. We determine the perturbative renormalization factor for a particular lattice discretization of this correlator within Wilson's SU(3) gauge theory, finding a ~12% NLO correction for values of the bare coupling used in the current generation of simulations. The impact of this result on existing lattice determinations is commented upon, and a possibility for non-perturbative renormalization through the gradient flow is pointed out.

  4. Perturbative renormalization of the electric field correlator

    Science.gov (United States)

    Christensen, C.; Laine, M.

    2016-04-01

    The momentum diffusion coefficient of a heavy quark in a hot QCD plasma can be extracted as a transport coefficient related to the correlator of two colour-electric fields dressing a Polyakov loop. We determine the perturbative renormalization factor for a particular lattice discretization of this correlator within Wilson's SU(3) gauge theory, finding a ∼ 12% NLO correction for values of the bare coupling used in the current generation of simulations. The impact of this result on existing lattice determinations is commented upon, and a possibility for non-perturbative renormalization through the gradient flow is pointed out.

  5. Perturbative renormalization of the electric field correlator

    Directory of Open Access Journals (Sweden)

    C. Christensen

    2016-04-01

    Full Text Available The momentum diffusion coefficient of a heavy quark in a hot QCD plasma can be extracted as a transport coefficient related to the correlator of two colour-electric fields dressing a Polyakov loop. We determine the perturbative renormalization factor for a particular lattice discretization of this correlator within Wilson's SU(3 gauge theory, finding a ∼12% NLO correction for values of the bare coupling used in the current generation of simulations. The impact of this result on existing lattice determinations is commented upon, and a possibility for non-perturbative renormalization through the gradient flow is pointed out.

  6. Electric field control of Skyrmions in magnetic nanodisks

    Science.gov (United States)

    Nakatani, Y.; Hayashi, M.; Kanai, S.; Fukami, S.; Ohno, H.

    2016-04-01

    The control of magnetic Skyrmions confined in a nanometer scale disk using electric field pulses is studied by micromagnetic simulation. A stable Skyrmion can be created and annihilated by an electric field pulse depending on the polarity of the electric field. Moreover, the core direction of the Skyrmion can be switched using the same electric field pulses. Such creation and annihilation of Skyrmions, and its core switching do not require any magnetic field and precise control of the pulse length. This unconventional manipulation of magnetic texture using electric field pulses allows a robust way of controlling magnetic Skyrmions in nanodiscs, a path toward building ultralow power memory devices.

  7. Nonlinear relaxation field in charged systems under high electric fields

    Energy Technology Data Exchange (ETDEWEB)

    Morawetz, K

    2000-07-01

    The influence of an external electric field on the current in charged systems is investigated. The results from the classical hierarchy of density matrices are compared with the results from the quantum kinetic theory. The kinetic theory yields a systematic treatment of the nonlinear current beyond linear response. To this end the dynamically screened and field-dependent Lenard-Balescu equation is integrated analytically and the nonlinear relaxation field is calculated. The classical linear response result known as Debye - On-Sager relaxation effect is only obtained if asymmetric screening is assumed. Considering the kinetic equation of one specie the other species have to be screened dynamically while the screening with the same specie itself has to be performed statically. Different other approximations are discussed and compared. (author)

  8. Brownian dipole rotator in alternating electric field

    Science.gov (United States)

    Rozenbaum, V. M.; Vovchenko, O. Ye.; Korochkova, T. Ye.

    2008-06-01

    The study addresses the azimuthal jumping motion of an adsorbed polar molecule in a periodic n -well potential under the action of an external alternating electric field. Starting from the perturbation theory of the Pauli equation with respect to the weak field intensity, explicit analytical expressions have been derived for the time dependence of the average dipole moment as well as the frequency dependences of polarizability and the average angular velocity, the three quantities exhibiting conspicuous stochastic resonance. As shown, unidirectional rotation can arise only provided simultaneous modulation of the minima and maxima of the potential by an external alternating field. For a symmetric potential of hindered rotation, the average angular velocity, if calculated by the second-order perturbation theory with respect to the field intensity, has a nonzero value only at n=2 , i.e., when two azimuthal wells specify a selected axis in the system. Particular consideration is given to the effect caused by the asymmetry of the two-well potential on the dielectric loss spectrum and other Brownian motion parameters. When the asymmetric potential in a system of dipole rotators arises from the average local fields induced by an orientational phase transition, the characteristics concerned show certain peculiarities which enable detection of the phase transition and determination of its parameters.

  9. Brownian dipole rotator in alternating electric field.

    Science.gov (United States)

    Rozenbaum, V M; Vovchenko, O Ye; Korochkova, T Ye

    2008-06-01

    The study addresses the azimuthal jumping motion of an adsorbed polar molecule in a periodic n -well potential under the action of an external alternating electric field. Starting from the perturbation theory of the Pauli equation with respect to the weak field intensity, explicit analytical expressions have been derived for the time dependence of the average dipole moment as well as the frequency dependences of polarizability and the average angular velocity, the three quantities exhibiting conspicuous stochastic resonance. As shown, unidirectional rotation can arise only provided simultaneous modulation of the minima and maxima of the potential by an external alternating field. For a symmetric potential of hindered rotation, the average angular velocity, if calculated by the second-order perturbation theory with respect to the field intensity, has a nonzero value only at n=2 , i.e., when two azimuthal wells specify a selected axis in the system. Particular consideration is given to the effect caused by the asymmetry of the two-well potential on the dielectric loss spectrum and other Brownian motion parameters. When the asymmetric potential in a system of dipole rotators arises from the average local fields induced by an orientational phase transition, the characteristics concerned show certain peculiarities which enable detection of the phase transition and determination of its parameters. PMID:18643221

  10. Electromagnetic processes in pulsars under strong electric and magnetic field conditions

    International Nuclear Information System (INIS)

    It is believed that pulsars possess huge electric and magnetic fields. However, the electric field is commonly neglected in calculations of the rate of pair production, a process which is thought to be greatly important in the radiation mechanisms of pulsars. To see the effect of the electric field, the pair production is calculated for arbitrary electric and magnetic field configurations. The formulae thus obtained are then applied to pulsars. It is shown that the correction to the ''polar gap'' height calculated in the Ruderman and Sutherland model is negligible, although it might be important for the spectrum of emerging photons. (author)

  11. Field enhancement factor dependence on electric field and implications on microscale gas breakdown: Theory and experimental interpretation

    Science.gov (United States)

    Alejandro Buendia, Jose; Venkattraman, Ayyaswamy

    2015-12-01

    In this letter, we obtain a better understanding of effective field enhancement factors (β eff) in the context of microscale gas breakdown with specific emphasis on its dependence on applied electric field. The theoretical dependence of β eff on electric field for various hemi-ellipsoidal asperities indicates that the value of β eff decreases with increasing electric field. The interpretation of experimental data using a typical one-dimensional modified Paschen law indicates a qualitatively similar electric field dependence even though the data could not be completely explained using a single effective asperity size. The values of β eff extracted from seven independent experimental datasets for microscale breakdown of argon and air are shown to be consistent and an empirical dependence on electric field is determined.

  12. Shielding ultracold dipolar molecular collisions with electric fields

    Science.gov (United States)

    Quéméner, Goulven; Bohn, John

    2016-05-01

    The prospect for shielding ultracold dipolar molecules from inelastic and reactive collisions is investigated. Molecules placed in their first rotationally excited states are found to exhibit effective long-range repulsion for applied electric fields above a certain critical value. This repulsion can safely allow the molecules to scatter while reducing the risk of inelastic or chemically reactive collisions. Several molecular species of molecules of experimental interest such as NaRb, NaK, RbSr, SrF, BaF, and YO, are considered and all are shown to exhibit orders of magnitude suppression in quenching rates in a sufficiently strong laboratory electric field. We acknowledge the financial support of the COPOMOL project (ANR-13-IS04-0004) from Agence Nationale de la Recherche and the ARO MURI Grant No. W911NF-12-1-0476.

  13. Fusion of bacterial spheroplasts by electric fields.

    Science.gov (United States)

    Ruthe, H J; Adler, J

    1985-09-25

    Spheroplasts of Escherichia coli or Salmonella typhimurium were found to fuse in an electric field. We employed the fusion method developed by Zimmermann and Scheurich (1981): Close membrane contact between cells is established by dielectrophoresis (formation of chains of cells by an a.c. field), then membrane fusion is induced by the application of short pulses of direct current. Under optimum conditions the fusion yield was routinely 90%. Fusable spheroplasts were obtained by first growing filamentous bacteria in the presence of cephalexin, then converting these to spheroplasts by the use of lysozyme. The fusion products were viable and regenerated to the regular bacterial form. Fusion of genetically different spheroplasts resulted in strains of bacteria possessing a combination of genetic markers. Fusion could not be achieved with spheroplasts obtained by growing the cells in the presence of penicillin or by using lysozyme on bacteria of usual size. PMID:3899175

  14. The impact of space electric field research on atmospheric studies

    Science.gov (United States)

    Mozer, F. S.

    1974-01-01

    Space measurements of electric fields have provided instrumentation for measuring atmospheric parameters and a better basis for understanding the electrical coupling between the magnetosphere and the atmosphere. Applications of an incoherent scatter radar (developed for ionospheric electric field research) to the measurement of atmospheric winds and turbulence and of Langmuir double probes (also developed for space research) for measurement of atmospheric electric fields are described. The increased knowledge of magnetospheric electric fields has focused attention on the electrical coupling between the magnetosphere and the atmosphere with conclusions that should considerably modify previous physical concepts in both domains.

  15. Electrical properties of two-dimensional thin films of the ferroelectric material Polyvinylidene Fluoride as a function of electric field

    Energy Technology Data Exchange (ETDEWEB)

    Belouadah, R., E-mail: r_belouadah74@yahoo.f [Departement de physique, Universite de M' sila, PB 116 Ichebilia, M' sila (Algeria); Laboratoire des Systemes Integres a base de Capteurs, Ecole Normale Superieure B.P 92 Kouba, Alger (Algeria); Kendil, D.; Bousbiat, E. [Laboratoire des Systemes Integres a base de Capteurs, Ecole Normale Superieure B.P 92 Kouba, Alger (Algeria); Guyomar, D.; Guiffard, B. [Laboratoire de Genie Electrique et Ferroelectricite, INSA-Lyon, Bat. Gustave Ferrie, 8 rue de la Physique, Villeurbanne (France)

    2009-06-01

    The study of the electrical properties of two-dimensional ferroelectric materials is very interesting because of the many possible applications relating to effects on their polarization properties. In this work we study the effect of a sinusoidal electric field on the dielectric and electrical properties of uni-axially and biaxially stretched polyvinylidene fluoride (PVDF) films. We have determined the polarization current, remanent polarization, maximal polarization, the hysteresis loop and coercive field as a function of applied electric field amplitude. The most interesting effects are the electric field (E) dependences of the resistivity. It is shown that for the biaxially stretched PVDF sample, the resistivity is almost constant, whereas for the uni-axially stretched specimen, a large decrease of resistivity is observed.

  16. Electrical properties of two-dimensional thin films of the ferroelectric material Polyvinylidene Fluoride as a function of electric field

    International Nuclear Information System (INIS)

    The study of the electrical properties of two-dimensional ferroelectric materials is very interesting because of the many possible applications relating to effects on their polarization properties. In this work we study the effect of a sinusoidal electric field on the dielectric and electrical properties of uni-axially and biaxially stretched polyvinylidene fluoride (PVDF) films. We have determined the polarization current, remanent polarization, maximal polarization, the hysteresis loop and coercive field as a function of applied electric field amplitude. The most interesting effects are the electric field (E) dependences of the resistivity. It is shown that for the biaxially stretched PVDF sample, the resistivity is almost constant, whereas for the uni-axially stretched specimen, a large decrease of resistivity is observed.

  17. The induced electric field distribution in the solar atmosphere

    Institute of Scientific and Technical Information of China (English)

    Rong Chen; Zhi-Liang Yang; Yuan-Yong Deng

    2013-01-01

    A method of calculating the induced electric field is presented.The induced electric field in the solar atmosphere is derived by the time variation of the magnetic field when the accumulation of charged particles is neglected.In order to derive the spatial distribution of the magnetic field,several extrapolation methods are introduced.With observational data from the Helioseismic and Magnetic Imager aboard NASA's Solar Dynamics Observatory taken on 2010 May 20,we extrapolate the magnetic field from the photosphere to the upper atmosphere.By calculating the time variation of the magnetic field,we can get the induced electric field.The derived induced electric field can reach a value of 102 V cm-1 and the average electric field has a maximum point at the layer 360 km above the photosphere.The Monte Carlo method is used to compute the triple integration of the induced electric field.

  18. Neutron scattering techniques for betaine calcium chloride dihydrate under applied external field (temperature, electric field and hydrostatic pressure); Etude par diffusion de neutrons du chlorure de calcium et de betaine dihydrate sous champ externe applique (temperature, champ electrique et pression hydrostatique)

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez, O

    1997-11-17

    We have studied with neutron scattering techniques betaine calcium chloride dihydrate (BCCD), a dielectric aperiodic crystal which displays a Devil`s staircase type phase diagram made up of several incommensurate and commensurate phases, having a range of stability very sensitive to temperature, electric field and hydrostatic pressure. We have measured a global hysteresis of {delta}(T) of about 2-3 K in the two incommensurate phases. A structural study of the modulated commensurate phases 1/4 and 1/5 allows us to evidence that the atomic modulation functions are anharmonic. The relevance of the modelization of the modulated structure by polar Ising pseudo-spins is then directly established. On the basis of group theory calculation in the four dimensional super-space, we interpret this anharmonic modulation as a soliton regime with respect to the lowest-temperature non modulated ferroelectric phase. The continuous character of the transition to the lowest-temperature non modulated phase and the diffuse scattering observed in this phase are accounted for the presence of ferroelectric domains separated by discommensurations. Furthermore, we have shown that X-rays induce in BCCD a strong variation with time of irradiation of the intensity of satellite peaks, and more specifically for third order ones. This is why the `X-rays` structural model is found more harmonic than the `neutron` one. Under electric field applied along the vector b axis, we confirm that commensurate phases with {delta} = even/odd are favoured and hence are polar along this direction. We have evidenced at 10 kV / cm two new higher order commensurate phases in the phase INC2, corroborating the idea of a `complete` Devil`s air-case phase diagram. A phenomenon of generalized coexistence of phases occurs above 5 kV / cm. We have characterized at high field phase transitions between `coexisting` phases, which are distinguishable from classical lock-in transitions. Under hydrostatic pressure, our results

  19. Evaluation of DC electric field distribution of PPLP specimen based on the measurement of electrical conductivity in LN2

    Science.gov (United States)

    Hwang, Jae-Sang; Seong, Jae-Kyu; Shin, Woo-Ju; Lee, Jong-Geon; Cho, Jeon-Wook; Ryoo, Hee-Suk; Lee, Bang-Wook

    2013-11-01

    High temperature superconducting (HTS) cable has been paid much attention due to its high efficiency and high current transportation capability, and it is also regarded as eco-friendly power cable for the next generation. Especially for DC HTS cable, it has more sustainable and stable properties compared to AC HTS cable due to the absence of AC loss in DC HTS cable. Recently, DC HTS cable has been investigated competitively all over the world, and one of the key components of DC HTS cable to be developed is a cable joint box considering HVDC environment. In order to achieve the optimum insulation design of the joint box, analysis of DC electric field distribution of the joint box is a fundamental process to develop DC HTS cable. Generally, AC electric field distribution depends on relative permittivity of dielectric materials but in case of DC, electrical conductivity of dielectric material is a dominant factor which determines electric field distribution. In this study, in order to evaluate DC electric field characteristics of the joint box for DC HTS cable, polypropylene laminated paper (PPLP) specimen has been prepared and its DC electric field distribution was analyzed based on the measurement of electrical conductivity of PPLP in liquid nitrogen (LN2). Electrical conductivity of PPLP in LN2 has not been reported yet but it should be measured for DC electric field analysis. The experimental works for measuring electrical conductivity of PPLP in LN2 were presented in this paper. Based on the experimental works, DC electric field distribution of PPLP specimen was fully analyzed considering the steady state and the transient state of DC. Consequently, it was possible to determine the electric field distribution characteristics considering different DC applying stages including DC switching on, DC switching off and polarity reversal conditions.

  20. Hypersensitivity test to electric magnetic fields

    International Nuclear Information System (INIS)

    The so-called electromagnetic hypersensitivity (RH) syndrome includes a number of unspecific, medically unexplained symptoms attributed to exposure to electric and magnetic fields. As a whole, laboratory tests have provided inconclusive results, in part due to the fact that many individuals show nuclear, inconsistent responses to repeated experimental field-exposures. It has been proposed that such inconsistencies could be due in part to distress caused by the lab test itself. We have developed a test to be conducted at the patient's residence, allowing for long-term follow up of exposure-response assessment and avoiding the laboratory environment and the presence of the researcher as potential stressors and confounding factors. In a pilot test, EMDEX-II magnetometers were used to continuously recording power-frequency magnetic fields in the residence of a patient with perceived EH. The patient's symptoms included distress, headache and dizziness, among other ailments. Magnetographic data of a total of 123 recording days were plotted against the corresponding data on occurrence of the symptoms episodes. As a whole, the results did not show positive linear correlation between the daily occurrence of the episode and the exposures levels recorded during the day or during the day before. These preliminary results are little supportive of the hypothesis that the patient's ailments are caused or worsened by a putative hypersensitivity to residential exposure to power-frequency magnetic fields in the 0.02-4.00 μT range. (Author) 29 refs

  1. Effects of AC Electric Field on Small Laminar Nonpremixed Flames

    KAUST Repository

    Xiong, Yuan

    2015-04-01

    Electric field can be a viable method in controlling various combustion properties. Comparing to traditional actuators, an application of electric field requires very small power consumption. Especially, alternating current (AC) has received attention recently, since it could modulate flames appreciably even for the cases when direct current (DC) has minimal effects. In this study, the effect of AC electric fields on small coflow diffusion flames is focused with applications of various laser diagnostic techniques. Flow characteristics of baseline diffusion flames, which corresponds to stationary small coflow diffusion flames when electric field is not applied, were firstly investigated with a particular focus on the flow field in near-nozzle region with the buoyancy force exerted on fuels due to density differences among fuel, ambient air, and burnt gas. The result showed that the buoyancy force exerted on the fuel as well as on burnt gas significantly distorted the near-nozzle flow-fields. In the fuels with densities heavier than air, recirculation zones were formed very close to the nozzle exit. Nozzle heating effect influenced this near-nozzle flow-field particularly among lighter fuels. Numerical simulations were also conducted and the results showed that a fuel inlet boundary condition with a fully developed velocity profile for cases with long fuel tubes should be specified inside the fuel tube to obtain satisfactory agreement in both the flow and temperature fields with those from experiment. With sub-critical AC applied to the baseline flames, particle image velocimetry (PIV), light scattering, laser-induced incandescence (LII), and laser-induced fluores- cence (LIF) techniques were adopted to identify the flow field and the structures of OH, polycyclic aromatic hydrocarbons (PAHs), soot zone. Under certain AC condi- tions of applied voltage and frequency, the distribution of PAHs and the flow field near the nozzle exit were drastically altered from the

  2. Experimental Investigation of Integrated Optical Intensive Impulse Electric Field Sensors

    Institute of Scientific and Technical Information of China (English)

    SUN Bao; CHEN Fu-Shen

    2009-01-01

    We design and fabricate an integrated optical electric field sensor with segmented electrode for intensive im-pulse electric field measurement. The integrated optical sensor is based on a Mach-Zehnder interferometer with segmented electrodes. The output/input character of the sensing system is analysed and measured. The max-imal detectable electric field range (-75 kV/m to 245 kV/m) is obtained by analysing the results. As a result, the integrated optics electric field sensing system is suitable for transient intensive electric field measurement investigation.

  3. Retrieving Storm Electric Fields From Aircraft Field Mill Data. Part 2; Applications

    Science.gov (United States)

    Koshak, W. J.; Mach, D. M.; Christian, H. J.; Stewart, M. F.; Bateman, M. G.

    2005-01-01

    The Lagrange multiplier theory and "pitch down method" developed in Part I of this study are applied to complete the calibration of a Citation aircraft that is instrumented with six field mill sensors. When side constraints related to average fields are used, the method performs well in computer simulations. For mill measurement errors of 1 V/m and a 5 V/m error in the mean fair weather field function, the 3-D storm electric field is retrieved to within an error of about 12%. A side constraint that involves estimating the detailed structure of the fair weather field was also tested using computer simulations. For mill measurement errors of 1 V/m, the method retrieves the 3-D storm field to within an error of about 8% if the fair weather field estimate is typically within 1 V/m of the true fair weather field. Using this side constraint and data from fair weather field maneuvers taken on 29 June 2001, the Citation aircraft was calibrated. The resulting calibration matrix was then used to retrieve storm electric fields during a Citation flight on 2 June 2001. The storm field results are encouraging and agree favorably with the results obtained from earlier calibration analyses that were based on iterative techniques.

  4. Retrieving Storm Electric Fields from Aircrfaft Field Mill Data: Part II: Applications

    Science.gov (United States)

    Koshak, William; Mach, D. M.; Christian H. J.; Stewart, M. F.; Bateman M. G.

    2006-01-01

    The Lagrange multiplier theory developed in Part I of this study is applied to complete a relative calibration of a Citation aircraft that is instrumented with six field mill sensors. When side constraints related to average fields are used, the Lagrange multiplier method performs well in computer simulations. For mill measurement errors of 1 V m(sup -1) and a 5 V m(sup -1) error in the mean fair-weather field function, the 3D storm electric field is retrieved to within an error of about 12%. A side constraint that involves estimating the detailed structure of the fair-weather field was also tested using computer simulations. For mill measurement errors of 1 V m(sup -l), the method retrieves the 3D storm field to within an error of about 8% if the fair-weather field estimate is typically within 1 V m(sup -1) of the true fair-weather field. Using this type of side constraint and data from fair-weather field maneuvers taken on 29 June 2001, the Citation aircraft was calibrated. Absolute calibration was completed using the pitch down method developed in Part I, and conventional analyses. The resulting calibration matrices were then used to retrieve storm electric fields during a Citation flight on 2 June 2001. The storm field results are encouraging and agree favorably in many respects with results derived from earlier (iterative) techniques of calibration.

  5. Electric-field variations within a nematic-liquid-crystal layer.

    Science.gov (United States)

    Cummings, L J; Mema, E; Cai, C; Kondic, L

    2014-07-01

    A thin layer of nematic liquid crystal (NLC) across which an electric field is applied is a setup of great industrial importance in liquid crystal display devices. There is thus a large literature modeling this situation and related scenarios. A commonly used assumption is that an electric field generated by electrodes at the two bounding surfaces of the layer will produce a field that is uniform: that is, the presence of NLC does not affect the electric field. In this paper, we use calculus of variations to derive the equations coupling the electric potential to the orientation of the NLC's director field, and use a simple one-dimensional model to investigate the limitations of the uniform field assumption in the case of a steady applied field. The extension of the model to the unsteady case is also briefly discussed.

  6. Pair prediction in a static electric field

    Energy Technology Data Exchange (ETDEWEB)

    Bachega, Riis R.A. [Universidade Federal do Para (UFPA), PA (Brazil); Marques, Glauber T. [Universidade Federal Rural da Amazonia (UFRA), Belem, PA (Brazil); Universidade Federal do Para (UFPA), PA (Brazil)

    2011-07-01

    Full text: The development of the Relativistic Quantum Mechanics was held at the end of the twenties of last century aiming to describe quantum phenomena that occur at high energy scales. The first equation proposed to describe these phenomena was the Klein-Gordon equation, which was formulated in 1927 by Swedish physicist Oscar Klein and the German physicist Walter Gordon. However, the equation led to problematic outcomes, such as negative probability densities and negative energy eigenvalues, which meant a quantum system described by the Klein-Gordon equation can decay to a state energy -{infinity}, thus freeing an infinite amount of energy. Another strange prediction of Relativistic Quantum Mechanics is the well known Klein paradox, which relates a particle on a static electric field with a potential energy much greater than the energy of the particle, and it appears that the reflection coefficient exceeds unity. This result is explained qualitatively by the pair production of particle - antiparticle in the interface potential. To solve such problems, was proposed the Second Quantization, where the Klein-Gordon scalar field is transformed into an operator can no longer be interpreted as a wave function, as in Non-Relativistic Quantum Mechanics formulated by Schroedinger. Thus, we obtain a consistent unification of quantum mechanics with special relativity, solving the problems was discussed earlier. Under the Second Quantization, you can also get a quantitative understanding of Klein's paradox, which will be the topic discussed in this work. The pair production in a static electric field provides a great analogy for a subsequent study of pair production in the event horizon of a black hole, which is known Hawking Effect. (author)

  7. Saturation of the Electric Field Transmitted to the Magnetosphere

    Science.gov (United States)

    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.

  8. Electric Eels Concentrate Their Electric Field to Induce Involuntary Fatigue in Struggling Prey.

    Science.gov (United States)

    Catania, Kenneth C

    2015-11-16

    Nature is replete with predator venoms that immobilize prey by targeting ion channels. Electric eels (Electrophorus electricus) take a different tactic to accomplish the same end. Striking eels emit electricity in volleys of 1 ms, high-voltage pulses. Each pulse is capable of activating prey motor neuron efferents, and hence muscles. In a typical attack, eel discharges cause brief, immobilizing tetanus, allowing eels to swallow small prey almost immediately. Here I show that when eels struggle with large prey or fish held precariously, they commonly curl to bring their own tail to the opposite side of prey, sandwiching it between the two poles of their powerful electric organ. They then deliver volleys of high-voltage pulses. Shortly thereafter, eels juggle prey into a favorable position for swallowing. Recordings from electrodes placed within prey items show that this curling behavior at least doubles the field strength within shocked prey, most likely ensuring reliable activation of the majority of prey motor neurons. Simulated pulse trains, or pulses from an eel-triggered stimulator, applied to a prey muscle preparations result in profound muscle fatigue and loss of contractile force. Consistent with this result, video recordings show that formerly struggling prey are temporarily immobile after this form of attack, allowing the manipulation of prey that might otherwise escape. These results reveal a unique use of electric organs to a unique end; eels superimpose electric fields from two poles, ensuring maximal remote activation of prey efferents that blocks subsequent prey movement by inducing involuntary muscle fatigue.

  9. Functionally Graded Interfaces: Role and Origin of Internal Electric Field and Modulated Electrical Response.

    Science.gov (United States)

    Maurya, Deepam; Zhou, Yuan; Chen, Bo; Kang, Min-Gyu; Nguyen, Peter; Hudait, Mantu K; Priya, Shashank

    2015-10-14

    We report the tunable electrical response in functionally graded interfaces in lead-free ferroelectric thin films. Multilayer thin film graded heterostructures were synthesized on platinized silicon substrate with oxide layers of varying thickness. Interestingly, the graded heterostructure thin films exhibited shift of the hysteresis loops on electric field and polarization axes depending upon the direction of an applied bias. A diode-like characteristics was observed in current-voltage behavior under forward and reverse bias. This modulated electrical behavior was attributed to the perturbed dynamics of charge carriers under internal bias (self-bias) generated due to the increased skewness of the potential wells. The cyclic sweeping of voltage further demonstrated memristor-like current-voltage behavior in functionally graded heterostructure devices. The presence of an internal bias assisted the generation of photocurrent by facilitating the separation of photogenerated charges. These novel findings provide opportunity to design new circuit components for the next generation of microelectronic device architectures. PMID:26378954

  10. Calculation of Electric Field Characteristics of Insulator Under Sandstorm Condition

    OpenAIRE

    Zhao Shanpeng; Zhang Youpeng; Chen Zhidong; Dong Haiyan

    2013-01-01

    Sandstorm has influence on the the electrical properties of outdoor insulator, and the analysis of the electric field characteristics of insulator under sandstorm condition is very important. The electrostatic field finite element method (FEM) is used to calculate the electric field distribution along long rod insulator under sandstorm condition with FEM software after calculating the one under clean condition. The results of calculation show that the sand deposition decreases the electric fi...

  11. Effect of Electric and Magnetic Fields on Spin Dynamics in the Resonant Electric Dipole Moment Experiment

    OpenAIRE

    Silenko, A. J.

    2013-01-01

    A buildup of the vertical polarization in the resonant electric dipole moment (EDM) experiment [Y. F. Orlov, W. M. Morse, and Y. K. Semertzidis, Phys. Rev. Lett. 96, 214802 (2006)] is affected by a horizontal electric field in the particle rest frame oscillating at a resonant frequency. This field is defined by the Lorentz transformation of an oscillating longitudinal electric field and a uniform vertical magnetic one. The effect of a longitudinal electric field is significant, while the cont...

  12. EMERGING TECHNOLOGY SUMMARY: THEORETICAL AND EXPERIMENTAL MODELING OF MULTI-SPECIES TRANSPORT IN SOILS UNDER ELECTRIC FIELDS

    Science.gov (United States)

    This project investigated an innovative approach for transport of inorganic species under the influence of electric fields. This process, commonly known as electrokinetics uses low-level direct current (dc) electrical potential difference across a soil mass applied through inert...

  13. Numerical simulation of the leaky dielectric microdroplet generation in electric fields

    Science.gov (United States)

    Kamali, Reza; Manshadi, Mohammad Karim Dehghan

    2016-07-01

    Microdroplet generation has a vast range of applications in the chemical, biomedical, and biological sciences. Several devices are applied to produce microdroplets, such as Co-flow, T-junction and Flow-focusing. The important point in the producing process is controlling the separated fluid volume in these devices. On the other hand, a large number of liquids, especially aqueous one, are influenced by electric or magnetic fields. As a consequence, an electric field could be used in order to affect the separated fluid volume. In this study, effects of an electric field on the microdroplet generation in a Co-flow device are investigated numerically. Furthermore, effects of some electrical properties such as permittivity on the separating process of microdroplets are studied. Leaky dielectric and perfect dielectric models are used in this investigation. According to the results, in the microdroplet generating process, leaky dielectric fluids show different behaviors, when an electric field is applied to the device. In other words, in a constant electric field strength, the volume of generated microdroplets can increase or decrease, in comparison with the condition without the electric field. However, for perfect dielectric fluids, droplet volume always decreases with increasing the electric field strength. In order to validate the numerical method of this study, deformation of a leaky dielectric droplet in an electric field is investigated. Results are compared with Taylor theoretical model.

  14. Switching local magnetization by electric-field-induced domain wall motion

    Science.gov (United States)

    Kakizakai, Haruka; Ando, Fuyuki; Koyama, Tomohiro; Yamada, Kihiro; Kawaguchi, Masashi; Kim, Sanghoon; Kim, Kab-Jin; Moriyama, Takahiro; Chiba, Daichi; Ono, Teruo

    2016-06-01

    Electric field effect on magnetism is an appealing technique for manipulating magnetization at a low energy cost. Here, we show that the local magnetization of an ultrathin Co film can be switched by simply applying a gate electric field without the assistance of any external magnetic field or current flow. The local magnetization switching is explained by nucleation and annihilation of magnetic domains through domain wall motion induced by the electric field. Our results lead to external-field-free and ultralow-energy spintronic applications.

  15. Direct observation of electric field induced pattern formation and particle aggregation in ferrofluids

    Energy Technology Data Exchange (ETDEWEB)

    Rajnak, Michal; Kopcansky, Peter; Timko, Milan [Institute of Experimental Physics SAS, Watsonova 47, 04001 Košice (Slovakia); Petrenko, Viktor I. [Joint Institute for Nuclear Research, Joliot-Curie 6, 141980 Dubna, Moscow Region (Russian Federation); Kyiv Taras Shevchenko National University, Volodymyrska Street 64, Kyiv 01033 (Ukraine); Avdeev, Mikhail V. [Joint Institute for Nuclear Research, Joliot-Curie 6, 141980 Dubna, Moscow Region (Russian Federation); Ivankov, Olexandr I. [Joint Institute for Nuclear Research, Joliot-Curie 6, 141980 Dubna, Moscow Region (Russian Federation); Kyiv Taras Shevchenko National University, Volodymyrska Street 64, Kyiv 01033 (Ukraine); Moscow Institute of Physics and Technology, Institutskiy per. 9, Dolgoprudniy 141700 (Russian Federation); Feoktystov, Artem [Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH, Lichtenbergstr. 1, 85747 Garching (Germany); Dolnik, Bystrik; Kurimsky, Juraj [Faculty of Electrical Engineering and Informatics, Technical University of Košice, Letná 9, 04200 Košice (Slovakia)

    2015-08-17

    Ferrofluids typically respond to magnetic fields and can be manipulated by external magnetic fields. Here, we report on formation of visually observable patterns in a diluted low-polarity ferrofluid exposed to external electric fields. This presents a specific type of ferrofluid structure driven by a combined effect of electrohydrodynamics and electrical body forces. The free charge and permittivity variation are considered to play a key role in the observed phenomenon. The corresponding changes in the ferrofluid structure have been found at nanoscale as well. By small-angle neutron scattering (SANS), we show that the magnetic nanoparticles aggregate in direct current (dc) electric field with a strong dependence on the field intensity. The anisotropic aggregates preferably orient in the direction of the applied electric field. Conducting SANS experiments with alternating current (ac) electric fields of various frequencies, we found a critical frequency triggering the aggregation process. Our experimental study could open future applications of ferrofluids based on insulating liquids.

  16. Direct observation of electric field induced pattern formation and particle aggregation in ferrofluids

    Science.gov (United States)

    Rajnak, Michal; Petrenko, Viktor I.; Avdeev, Mikhail V.; Ivankov, Olexandr I.; Feoktystov, Artem; Dolnik, Bystrik; Kurimsky, Juraj; Kopcansky, Peter; Timko, Milan

    2015-08-01

    Ferrofluids typically respond to magnetic fields and can be manipulated by external magnetic fields. Here, we report on formation of visually observable patterns in a diluted low-polarity ferrofluid exposed to external electric fields. This presents a specific type of ferrofluid structure driven by a combined effect of electrohydrodynamics and electrical body forces. The free charge and permittivity variation are considered to play a key role in the observed phenomenon. The corresponding changes in the ferrofluid structure have been found at nanoscale as well. By small-angle neutron scattering (SANS), we show that the magnetic nanoparticles aggregate in direct current (dc) electric field with a strong dependence on the field intensity. The anisotropic aggregates preferably orient in the direction of the applied electric field. Conducting SANS experiments with alternating current (ac) electric fields of various frequencies, we found a critical frequency triggering the aggregation process. Our experimental study could open future applications of ferrofluids based on insulating liquids.

  17. Enhance soil bioremediation with electric fields

    International Nuclear Information System (INIS)

    Electrokinetic remediation is an in situ remediation technique that uses low-level direct-current electric potential differences (on the order of volts per centimeter) or an electric current (on the order of milliamps per square centimeter of cross-sectional area between electrodes) applied across a soil mass by electrodes placed in an open- or closed-flow arrangement. In electrokinetic methods, the groundwater in the boreholes or an externally supplied fluid (processing fluid) is used as the conductive medium. Electrokinetic remediation technology for metal extraction is expected to decrease the cost of remediating contaminated soils to the lower end of the $100--$1,000/m3 range. This would be a significant savings in the $350 billion hazardous waste site cleanup and remediation market. The environmental restoration cost for the mixed (radioactive)-waste market is separately estimated to be $65 billion. The potential of the electrokinetic remediation technique in remediating soils contaminated with radioactive mixed waste using depolarization agents and complexing agents is noteworthy. The authors have removed uranyl ions from spiked kaolinite using the technique

  18. Can Neural Activity Propagate by Endogenous Electrical Field?

    Science.gov (United States)

    Qiu, Chen; Shivacharan, Rajat S; Zhang, Mingming; Durand, Dominique M

    2015-12-01

    It is widely accepted that synaptic transmissions and gap junctions are the major governing mechanisms for signal traveling in the neural system. Yet, a group of neural waves, either physiological or pathological, share the same speed of ∼0.1 m/s without synaptic transmission or gap junctions, and this speed is not consistent with axonal conduction or ionic diffusion. The only explanation left is an electrical field effect. We tested the hypothesis that endogenous electric fields are sufficient to explain the propagation with in silico and in vitro experiments. Simulation results show that field effects alone can indeed mediate propagation across layers of neurons with speeds of 0.12 ± 0.09 m/s with pathological kinetics, and 0.11 ± 0.03 m/s with physiologic kinetics, both generating weak field amplitudes of ∼2-6 mV/mm. Further, the model predicted that propagation speed values are inversely proportional to the cell-to-cell distances, but do not significantly change with extracellular resistivity, membrane capacitance, or membrane resistance. In vitro recordings in mice hippocampi produced similar speeds (0.10 ± 0.03 m/s) and field amplitudes (2.5-5 mV/mm), and by applying a blocking field, the propagation speed was greatly reduced. Finally, osmolarity experiments confirmed the model's prediction that cell-to-cell distance inversely affects propagation speed. Together, these results show that despite their weak amplitude, electric fields can be solely responsible for spike propagation at ∼0.1 m/s. This phenomenon could be important to explain the slow propagation of epileptic activity and other normal propagations at similar speeds. PMID:26631463

  19. Physics of magnetic insulation failure of charge streams in crossed electric and magnetic fields

    International Nuclear Information System (INIS)

    This work is devoted to physical problems of a magnetic insulating failure for the dense charge collisionless beams in a gap with applied crossed electric and magnetic fields. The analysis is provided at example of an electron flow in a magnetron diode (MD). The MD is a vacuum coaxial diode with longitudinal magnetic field and cylindrical cathode and anode with applied a pulsed voltage

  20. Manipulation of nano-entities in suspension by electric fields

    Science.gov (United States)

    Fan, Donglei

    Nanoscale entities, including nanospheres, nanodisks, nanorings, nanowires and nanotubes are potential building blocks for nanoscale devices. Among them, nanowires is an important type of nanoparticles, due to the potential application in microelectronics and bio-diagnosis. Manipulation of nanowires in suspension has been a formidable problem. As described in this thesis, using AC electric fields applied to strategically designed microelectrodes, nanowires in suspension can be driven to align, to chain, to accelerate in directions parallel and perpendicular to its orientation, to concentrate onto designated places, and to disperse in a controlled manner with high efficiency despite an extremely low Reynolds number at the level of 10-5. Randomly oriented nanowires in suspension can be rapidly assembled into extended nonlinear structures within seconds. We show that both the electric field and its gradient play the essential roles of aligning and transporting the nanowires into scaffolds according to the electric field distributions inherent to the geometry of the microelectrodes. The assembling efficiency depends strongly on the frequency of the applied AC voltages and varies as square of the voltage. Furthermore, nanowires have been rotated by AC electric fields applied to strategically designed electrodes. The rotation of the nanowires can be instantly switched on or off with precisely controlled rotation speed (to at least 25000 rpm), definite chirality, and total angle of rotation. This new method has been used to controllably rotate magnetic and non-magnetic nanowires as well as multi-wall carbon nanotubes. We have also produced a micromotor using a rotating nanowire that can drive particles into circular motion. This has application to microfluidic devices, micro-stirrers, and micro electromechanical systems (MEMS). To move and place nanowires onto designated locations with high precision, electrophoretic force has been combined with dielectrophoretic force to

  1. Patchy particle packing under electric fields.

    Science.gov (United States)

    Song, Pengcheng; Wang, Yufeng; Wang, Yu; Hollingsworth, Andrew D; Weck, Marcus; Pine, David J; Ward, Michael D

    2015-03-01

    Colloidal particles equipped with two, three, or four negatively charged patches, which endow the particles with 2-fold, 3-fold, or tetrahedral symmetries, form 1D chains, 2D layers, and 3D packings when polarized by an AC electric field. Two-patch particles, with two patches on opposite sides of the particle (2-fold symmetry) pack into the cmm plane group and 3D packings with I4mm space group symmetry, in contrast to uncharged spherical or ellipsoidal colloids that typically crystallize into a face-centered ABC layer packing. Three-patch particles (3-fold symmetry) form chains having a 21 screw axis symmetry, but these chains pair in a manner such that each individual chain has one-fold symmetry but the pair has 21 screw axis symmetry, in an arrangement that aligns the patches that would favor Coulombic interactions along the chain. Surprisingly, some chain pairs form unanticipated double-helix regions that result from mutual twisting of the chains about each other, illustrating a kind of polymorphism that may be associated with nucleation from short chain pairs. Larger 2D domains of the three-patch particles crystallize in the p6m plane group with alignment (with respect to the field) and packing densities that suggest random disorder in the domains, whereas four-patch particles form 2D domains in which close-packed rows are aligned with the field.

  2. Liquid methanol under a static electric field

    Energy Technology Data Exchange (ETDEWEB)

    Cassone, Giuseppe, E-mail: giuseppe.cassone@impmc.upmc.fr [Sorbonne Universités, UPMC Univ Paris 06, UMR 7590, IMPMC, F-75005 Paris (France); CNRS, UMR 7590, IMPMC, F-75005 Paris (France); Università degli Studi di Messina, Dipartimento di Fisica e di Scienze della Terra, Contrada Papardo, 98166 Messina (Italy); CNR-IPCF, Viale Ferdinando Stagno d’Alcontres 37, 98158 Messina (Italy); Giaquinta, Paolo V., E-mail: paolo.giaquinta@unime.it [Università degli Studi di Messina, Dipartimento di Fisica e di Scienze della Terra, Contrada Papardo, 98166 Messina (Italy); Saija, Franz, E-mail: saija@ipcf.cnr.it [CNR-IPCF, Viale Ferdinando Stagno d’Alcontres 37, 98158 Messina (Italy); Saitta, A. Marco, E-mail: marco.saitta@impmc.upmc.fr [Sorbonne Universités, UPMC Univ Paris 06, UMR 7590, IMPMC, F-75005 Paris (France); CNRS, UMR 7590, IMPMC, F-75005 Paris (France)

    2015-02-07

    We report on an ab initio molecular dynamics study of liquid methanol under the effect of a static electric field. We found that the hydrogen-bond structure of methanol is more robust and persistent for field intensities below the molecular dissociation threshold whose value (≈0.31 V/Å) turns out to be moderately larger than the corresponding estimate obtained for liquid water. A sustained ionic current, with ohmic current-voltage behavior, flows in this material for field intensities above 0.36 V/Å, as is also the case of water, but the resulting ionic conductivity (≈0.40 S cm{sup −1}) is at least one order of magnitude lower than that of water, a circumstance that evidences a lower efficiency of proton transfer processes. We surmise that this study may be relevant for the understanding of the properties and functioning of technological materials which exploit ionic conduction, such as direct-methanol fuel cells and Nafion membranes.

  3. Mapping of steady-state electric fields and convective drifts in geomagnetic fields - Part 2: The IGRF

    Science.gov (United States)

    Walker, A. D. M.

    2016-01-01

    A method of mapping electric fields along geomagnetic field lines is applied to the IGRF (International Geomagnetic Reference Field) model. The method involves integrating additional sets of first order differential equations simultaneously with those for tracing a magnetic field line. These provide a measure of the rate of change of the separation of two magnetic field lines separated by an infinitesimal amount. From the results of the integration Faraday's law is used to compute the electric field as a function of position along the field line. Examples of computations from a software package developed to implement the method are presented. This is expected to be of use in conjugate studies of magnetospheric phenomena such as SuperDARN (Super Dual Auroral Radar) observations of convection in conjugate hemispheres, or comparison of satellite electric field observations with fields measured in the ionosphere.

  4. Energy consumption in Hodgkin–Huxley type fast spiking neuron model exposed to an external electric field

    Directory of Open Access Journals (Sweden)

    K. Usha

    2016-09-01

    Full Text Available This paper evaluates the change in metabolic energy required to maintain the signalling activity of neurons in the presence of an external electric field. We have analysed the Hodgkin–Huxley type conductance based fast spiking neuron model as electrical circuit by changing the frequency and amplitude of the applied electric field. The study has shown that, the presence of electric field increases the membrane potential, electrical energy supply and metabolic energy consumption. As the amplitude of applied electric field increases by keeping a constant frequency, the membrane potential increases and consequently the electrical energy supply and metabolic energy consumption increases. On increasing the frequency of the applied field, the peak value of membrane potential after depolarization gradually decreases as a result electrical energy supply decreases which results in a lower rate of hydrolysis of ATP molecules.

  5. Periodicals in the Field of Applied Linguistics. An International Survey.

    Science.gov (United States)

    Okreglak, Ludmila, Comp.; Taylor, Marcia E., Comp.

    This volume lists and classifies journal literature in the field of applied linguistics. More than 200 periodicals are cited. Although emphasis is placed on publications dealing with language teaching, journals concerned with other aspects of applied linguistics are also included. The entries are arranged in alphabetical order, with foreign…

  6. Resistive memory effects in BiFeO3 single crystals controlled by transverse electric fields

    Science.gov (United States)

    Kawachi, S.; Kuroe, H.; Ito, T.; Miyake, A.; Tokunaga, M.

    2016-04-01

    The effects of electric fields perpendicular to the c-axis of the trigonal cell in single crystals of BiFeO3 are investigated through magnetization and resistance measurements. Magnetization and resistance exhibit hysteretic changes under applied electric fields, which can be ascribed to the reorientation of the magnetoelectric domains. Samples are repetitively switched between high- and low-resistance states by changing the polarity of the applied electric fields over 20 000 cycles at room temperature. These results demonstrate the potential of BiFeO3 for use in non-volatile memory devices.

  7. Structural characterization of electric-field assisted dip-coating of gold nanoparticles on silicon

    OpenAIRE

    Ghada H. Dushaq; Amro Alkhatib; Mahmoud S. Rasras; Nayfeh, Ammar M.

    2015-01-01

    We report the effect of applying an electric field on the surface coverage of 40nm gold colloidal nanoparticles on silicon wafer using dip-coating and electrochemical cell set up. By applying electric field during the dip-coating of silicon wafer in a solution of gold nano particles (GNP) the surface coverage increased by 10% when the electric field varied from 5V/cm to 25V/cm at fixed deposition time of 90s. Ultra High Resolution Scanning Electron Microscopy (HRSEM) images shows that the par...

  8. Electric-field-induced structural changes in water confined between two graphene layers

    Science.gov (United States)

    Sobrino Fernández, Mario; Peeters, F. M.; Neek-Amal, M.

    2016-07-01

    An external electric field changes the physical properties of polar liquids due to the reorientation of their permanent dipoles. Using molecular dynamics simulations, we predict that an in-plane electric field applied parallel to the channel polarizes water molecules which are confined between two graphene layers, resulting in distinct ferroelectricity and electrical hysteresis. We found that electric fields alter the in-plane order of the hydrogen bonds: Reversing the electric field does not restore the system to the nonpolar initial state, instead a residual dipole moment remains in the system. The square-rhombic structure of 2D ice is transformed into two rhombic-rhombic structures. Our study provides insights into the ferroelectric state of water when confined in nanochannels and shows how this can be tuned by an electric field.

  9. MTX microwave-electric-field diagnostic

    International Nuclear Information System (INIS)

    A joint Japan-U.S. project is in progress to measure the high electric fields produced by a free-electron laser beam of GW-peak-power level when injected into the plasma of the Microwave Tokamak Experiment (MTX) at the Lawrence Livermore National Laboratory in California. In this report, we discuss the planned method of measurement and the status of the work. The equipment needed is either well along in the design stage or is being built. We plan to test out the combined operation of all components in Japan before shipping to Livermore. Although the measurement appears difficult for a variety of technical and physics reasons, calculations indicate that it should be possible. (author)

  10. Difficulties in Learning the Concept of Electric Field.

    Science.gov (United States)

    Furio, C.; Guisasola, J.

    1998-01-01

    Analyzes students' main difficulties in learning the concept of electric field. Briefly describes the main conceptual profiles within which electric interactions can be interpreted and concludes that most students have difficulty using the idea of electric field. Contains 28 references. (DDR)

  11. Applying mathematical finance tools to the competitive Nordic electricity market

    International Nuclear Information System (INIS)

    This thesis models competitive electricity markets using the methods of mathematical finance. Fundamental problems of finance are market price modelling, derivative pricing, and optimal portfolio selection. The same questions arise in competitive electricity markets. The thesis presents an electricity spot price model based on the fundamental stochastic factors that affect electricity prices. The resulting price model has sound economic foundations, is able to explain spot market price movements, and offers a computationally efficient way of simulating spot prices. The thesis shows that the connection between spot prices and electricity forward prices is nontrivial because electricity is a commodity that must be consumed immediately. Consequently, forward prices of different times are based on the supply-demand conditions at those times. This thesis introduces a statistical model that captures the main characteristics of observed forward price movements. The thesis presents the pricing problems relating to the common Nordic electricity derivatives, as well as the pricing relations between electricity derivatives. The special characteristics of electricity make spot electricity market incomplete. The thesis assumes the existence of a risk-neutral martingale measure so that formal pricing results can be obtained. Some concepts introduced in financial markets are directly usable in the electricity markets. The risk management application in this thesis uses a static optimal portfolio selection framework where Monte Carlo simulation provides quantitative results. The application of mathematical finance requires careful consideration of the special characteristics of the electricity markets. Economic theory and reasoning have to be taken into account when constructing financial models in competitive electricity markets. (orig.)

  12. Electric-field-controlled unpinning of scroll waves

    Science.gov (United States)

    Jiménez, Zulma A.; Zhang, Zhihui; Steinbock, Oliver

    2013-11-01

    Three-dimensional excitation vortices exist in systems such as chemical reactions and the human heart. Their one-dimensional rotation backbone can pin to unexcitable heterogeneities, which greatly affect the structure, dynamics, and lifetime of the vortex. In experiments with the Belousov-Zhabotinsky reaction, we demonstrate vortex unpinning from a pair of inert and impermeable spheres using externally applied electric fields. Unpinning occurs abruptly but is preceded by a slow reorientation and deformation of the initially circular vortex loop. Our experimental findings are reproduced by numerical simulations of an excitable reaction-diffusion-advection model.

  13. Electric field effects on armchair MoS2 nanoribbons.

    Science.gov (United States)

    Dolui, Kapildeb; Pemmaraju, Chaitanya Das; Sanvito, Stefano

    2012-06-26

    Ab initio density functional theory calculations are performed to investigate the electronic structure of MoS(2) armchair nanoribbons in the presence of an external static electric field. Such nanoribbons, which are nonmagnetic and semiconducting, exhibit a set of weakly interacting edge states whose energy position determines the band gap of the system. We show that, by applying an external transverse electric field, E(ext), the nanoribbon band gap can be significantly reduced, leading to a metal-insulator transition beyond a certain critical value. Moreover, the presence of a sufficiently high density of states at the Fermi level in the vicinity of the metal-insulator transition leads to the onset of Stoner ferromagnetism that can be modulated, and even extinguished, by E(ext). In the case of bilayer nanoribbons we further show that the band gap can be changed from indirect to direct by applying a transverse field, an effect that might be of significance for opto-electronics applications. PMID:22546015

  14. A generalization information management system applied to electrical distribution

    Energy Technology Data Exchange (ETDEWEB)

    Geisler, K.I.; Neumann, S.A.; Nielsen, T.D.; Bower, P.K. (Empros Systems International (US)); Hughes, B.A.

    1990-07-01

    This article presents a system solution approach that meets the requirements being imposed by industry trends and the electric utility customer. Specifically, the solution addresses electric distribution management systems. Electrical distribution management is a particularly well suited area of application because it involves a high diversity of tasks, which are currently supported by a proliferation of automated islands. Islands of automation which currently exist include (among others) distribution operations, load management, automated mapping, facility management, work order processing, and planning.

  15. Dynamics of Drop Formation in an Electric Field.

    Science.gov (United States)

    Notz; Basaran

    1999-05-01

    The effect of an electric field on the formation of a drop of an inviscid, perfectly conducting liquid from a capillary which protrudes from the top plate of a parallel-plate capacitor into a surrounding dynamically inactive, insulating gas is studied computationally. This free boundary problem which is comprised of the surface Bernoulli equation for the transient drop shape and the Laplace equation for the velocity potential inside the drop and the electrostatic potential outside the drop is solved by a method of lines incorporating the finite element method for spatial discretization. The finite element algorithm employed relies on judicious use of remeshing and element addition to a two-region adaptive mesh to accommodate large domain deformations, and allows the computations to proceed until the thickness of the neck connecting an about to form drop to the rest of the liquid in the capillary is less than 0.1% of the capillary radius. The accuracy of the computations is demonstrated by showing that in the absence of an electric field predictions made with the new algorithm are in excellent agreement with boundary integral calculations (Schulkes, R. M. S. M. J. Fluid Mech. 278, 83 (1994)) and experimental measurements on water drops (Zhang, X., and Basaran, O. A. Phys. Fluids 7(6), 1184 (1995)). In the presence of an electric field, the algorithm predicts that as the strength of the applied field increases, the mode of drop formation changes from simple dripping to jetting to so-called microdripping, in accordance with experimental observations (Cloupeau, M., and Prunet-Foch, B. J. Aerosol Sci. 25(6), 1021 (1994); Zhang, X., and Basaran, O. A. J. Fluid Mech. 326, 239 (1996)). Computational predictions of the primary drop volume and drop length at breakup are reported over a wide range of values of the ratios of electrical, gravitational, and inertial forces to surface tension force. In contrast to previously mentioned cases where both the flow rate in the tube

  16. Calculation of Electric Field Characteristics of Insulator Under Sandstorm Condition

    Directory of Open Access Journals (Sweden)

    Zhao Shanpeng

    2013-09-01

    Full Text Available Sandstorm has influence on the the electrical properties of outdoor insulator, and the analysis of the electric field characteristics of insulator under sandstorm condition is very important. The electrostatic field finite element method (FEM is used to calculate the electric field distribution along long rod insulator under sandstorm condition with FEM software after calculating the one under clean condition. The results of calculation show that the sand deposition decreases the electric field strength of insulator covered with sand, and increases the field strength of the corresponding shed key points. The electric field strength of the non-sand region will increase, when the non-sand region appears in sand layer on insulator. Suspended sand particles in the ambient air can distort the electric field distribution along insulator, and which is significantly affected by the size, the quantity, the charge-to-mass ratio and the charge polarity of sand particles.

  17. Spin-wave propagation steered by electric field modulated exchange interaction.

    Science.gov (United States)

    Wang, Sheng; Guan, Xiawei; Cheng, Xiaomin; Lian, Chen; Huang, Ting; Miao, Xiangshui

    2016-01-01

    Combined ab initio and micromagnetic simulations are carried out to demonstrate the feasibility on the electrical manipulation of spin-wave propagation in ultrathin Fe films. It is discovered that the exchange interaction can be substantially weakened under the influence of electric field applied perpendicular to the magnetic film surface. Furthermore, we demonstrate that the electric field modified exchange constant could effectively control the propagation of spin waves. To be specific, an external applied electric field of 5 V/nm can effectively weaken exchange interaction by 80% and is sufficient to induce nearly twofold change of the wavenumber. This discovery may open a door to energy-efficient local manipulation of the spin wave propagation utilizing electric fields, which is crucial for both fundamental research and spin wave based logic applications. PMID:27587083

  18. Ex vivo and in silico feasibility study of monitoring electric field distribution in tissue during electroporation based treatments.

    Directory of Open Access Journals (Sweden)

    Matej Kranjc

    Full Text Available Magnetic resonance electrical impedance tomography (MREIT was recently proposed for determining electric field distribution during electroporation in which cell membrane permeability is temporary increased by application of an external high electric field. The method was already successfully applied for reconstruction of electric field distribution in agar phantoms. Before the next step towards in vivo experiments is taken, monitoring of electric field distribution during electroporation of ex vivo tissue ex vivo and feasibility for its use in electroporation based treatments needed to be evaluated. Sequences of high voltage pulses were applied to chicken liver tissue in order to expose it to electric field which was measured by means of MREIT. MREIT was also evaluated for its use in electroporation based treatments by calculating electric field distribution for two regions, the tumor and the tumor-liver region, in a numerical model based on data obtained from clinical study on electrochemotherapy treatment of deep-seated tumors. Electric field distribution inside tissue was successfully measured ex vivo using MREIT and significant changes of tissue electrical conductivity were observed in the region of the highest electric field. A good agreement was obtained between the electric field distribution obtained by MREIT and the actual electric field distribution in evaluated regions of a numerical model, suggesting that implementation of MREIT could thus enable efficient detection of areas with insufficient electric field coverage during electroporation based treatments, thus assuring the effectiveness of the treatment.

  19. Electric field effect on (6,0) zigzag single-walled aluminum nitride nanotube.

    Science.gov (United States)

    Baei, Mohammad T; Peyghan, Ali Ahmadi; Moghimi, Masoumeh

    2012-09-01

    Structural, electronic, and electrical responses of the H-capped (6,0) zigzag single-walled aluminum nitride nanotube was studied under the parallel and transverse electric fields with strengths 0-140 × 10(-4) a.u. by using density functional calculations. Geometry optimizations were carried out at the B3LYP/6-31G* level of theory using a locally modified version of the GAMESS electronic structure program. The dipole moments, atomic charge variations, and total energy of the (6,0) zigzag AlNNT show increases with increase in the applied external electric field strengths. The length, tip diameters, electronic spatial extent, and molecular volume of the nanotube do not significantly change with increasing electric field strength. The energy gap of the nanotube decreases with increases of the electric field strength and its reactivity is increased. Increase of the ionization potential, electron affinity, chemical potential, electrophilicity, and HOMO and LUMO in the nanotube with increase of the applied parallel electric field strengths shows that the parallel field has a much stronger interaction with the nanotube with respect to the transverse electric field strengths. Analysis of the parameters indicates that the properties of AlNNTs can be controlled by the proper external electric field.

  20. High-field electron transport in GaN under crossed electric and magnetic fields

    Science.gov (United States)

    Kochelap, V. A.; Korotyeyev, V. V.; Syngayivska, G. I.; Varani, L.

    2015-10-01

    High-field electron transport studied in crossed electric and magnetic fields in bulk GaN with doping of 1016 cm-3, compensation around 90% at the low lattice temperature (30 K). It was found the range of the magnetic and electric fields where the non-equilibrium electron distribution function has a complicated topological structure in the momentum space with a tendency to the formation of the inversion population. Field dependences of dissipative and Hall components of the drift velocity were calculated for the samples with short- and open- circuited Hall contacts in wide ranges of applied electric (0 — 20 kV/cm) and magnetic (1 — 10 T) fields. For former sample, field dependences of dissipative and Hall components of the drift velocity have a non-monotonic behavior. The dissipative component has the inflection point which corresponds to the maximum point of the Hall component. For latter sample, the drift velocity demonstrate a usual sub-linear growth without any critical points. We found that GaN samples with controlled resistance of the Hall circuit can be utilized as a electronic high-power switch.

  1. An Analysis of Electrical Impedance Measurements Applied for Plant N Status Estimation in Lettuce (Lactuca sativa

    Directory of Open Access Journals (Sweden)

    Rafael F. Muñoz-Huerta

    2014-06-01

    Full Text Available Nitrogen plays a key role in crop yields. Hence, farmers may apply excessive N fertilizers to crop fields, inducing environmental pollution. Crop N monitoring methods have been developed to improve N fertilizer management, most of them based on leaf or canopy optical-property measurements. However, sensitivity to environmental interference remains an important drawback. Electrical impedance has been applied to determine the physiological and nutritional status of plant tissue, but no studies related to plant-N contents are reported. The objective of this article is to analyze how the electrical impedance response of plants is affected by their N status. Four sets of lettuce (Lactuca sativa L. with a different N-source concentrations per set were used. Total nitrogen and electrical impedance spectra (in a 1 to 100 kHz frequency range were measured five times per set, three times every other day. Minimum phase angles of impedance spectra were detected and analyzed, together with the frequency value in which they occurred, and their magnitude at that frequency. High and positive correlation was observed between plant N content and frequency values at minimum phase angle with no significant variations detected between days of measurement. These results suggest that electrical impedance can be sensitive to plant N status.

  2. The influence of electric field and confinement on cell motility.

    Directory of Open Access Journals (Sweden)

    Yu-Ja Huang

    Full Text Available The ability of cells to sense and respond to endogenous electric fields is important in processes such as wound healing, development, and nerve regeneration. In cell culture, many epithelial and endothelial cell types respond to an electric field of magnitude similar to endogenous electric fields by moving preferentially either parallel or antiparallel to the field vector, a process known as galvanotaxis. Here we report on the influence of dc electric field and confinement on the motility of fibroblast cells using a chip-based platform. From analysis of cell paths we show that the influence of electric field on motility is much more complex than simply imposing a directional bias towards the cathode or anode. The cell velocity, directedness, as well as the parallel and perpendicular components of the segments along the cell path are dependent on the magnitude of the electric field. Forces in the directions perpendicular and parallel to the electric field are in competition with one another in a voltage-dependent manner, which ultimately govern the trajectories of the cells in the presence of an electric field. To further investigate the effects of cell reorientation in the presence of a field, cells are confined within microchannels to physically prohibit the alignment seen in 2D environment. Interestingly, we found that confinement results in an increase in cell velocity both in the absence and presence of an electric field compared to migration in 2D.

  3. The influence of electric field and confinement on cell motility.

    Science.gov (United States)

    Huang, Yu-Ja; Samorajski, Justin; Kreimer, Rachel; Searson, Peter C

    2013-01-01

    The ability of cells to sense and respond to endogenous electric fields is important in processes such as wound healing, development, and nerve regeneration. In cell culture, many epithelial and endothelial cell types respond to an electric field of magnitude similar to endogenous electric fields by moving preferentially either parallel or antiparallel to the field vector, a process known as galvanotaxis. Here we report on the influence of dc electric field and confinement on the motility of fibroblast cells using a chip-based platform. From analysis of cell paths we show that the influence of electric field on motility is much more complex than simply imposing a directional bias towards the cathode or anode. The cell velocity, directedness, as well as the parallel and perpendicular components of the segments along the cell path are dependent on the magnitude of the electric field. Forces in the directions perpendicular and parallel to the electric field are in competition with one another in a voltage-dependent manner, which ultimately govern the trajectories of the cells in the presence of an electric field. To further investigate the effects of cell reorientation in the presence of a field, cells are confined within microchannels to physically prohibit the alignment seen in 2D environment. Interestingly, we found that confinement results in an increase in cell velocity both in the absence and presence of an electric field compared to migration in 2D.

  4. The field of the vertical electric dipole immersed in the heterogeneous half-space

    Science.gov (United States)

    Barsukov, P. O.; Fainberg, E. B.

    2014-07-01

    The field of the vertical electric dipole (VED) immersed in the heterogeneous conductive halfspace (sea) is analyzed in time domain. In the near field of the source, the amplitudes of the electric and magnetic components of the field are proportional to power 3/2 and power 5/2 of the conductivity of the medium, respectively. After termination of the transmitter pulse, all the VED components decay with time as ˜1/ t 5/2. The possibility of applying the VED field for estimating the electrical properties of the offshore geological sections is demonstrated.

  5. Field-Induced Superconductivity in Electric Double Layer Transistors

    NARCIS (Netherlands)

    Ueno, Kazunori; Shimotani, Hidekazu; Yuan, Hongtao; Ye, Jianting; Kawasaki, Masashi; Iwasa, Yoshihiro

    2014-01-01

    Electric field tuning of superconductivity has been a long-standing issue in solid state physics since the invention of the field-effect transistor (FET) in 1960. Owing to limited available carrier density in conventional FET devices, electric-field-induced superconductivity was believed to be possi

  6. Giant enhancement of photodissociation of polar dimers in electric fields

    OpenAIRE

    González-Férez, R.; Schmelcher, P.

    2011-01-01

    We explore the photodissociation of polar dimers in static electric fields in the cold regime using the example of the LiCs molecule. A giant enhancement of the differential cross section is found for laboratory electric field strengths, and analyzed with varying rovibrational bound states, continuum energies as well as field strengths.

  7. The chromatographic separation of particles using optical electric fields

    DEFF Research Database (Denmark)

    Javier Alvarez, Nicolas; Jeppesen, Claus; Yvind, Kresten;

    2013-01-01

    We introduce a new field-flow fractionation (FFF) technique, whereby molecules are separated based on their differential interaction (dielectrophoresis (DEP)) with optical electric fields, i.e. electric fields with frequencies in the visible and near-infrared range. The results show that a parall...

  8. Generation of Electric Field and Net Charge in Hall Reconnection

    Institute of Scientific and Technical Information of China (English)

    MA Zhi-Wei; FENG Shu-Ling

    2008-01-01

    @@ Generation of Hall electric field and net charge associated with magnetic reconnection is studied under different initial conditions of plasma density and magnetic field. With inclusion of the Hall effects, decoupling of the electron and ion motions leads to the formation of a narrow layer with strong electric field and large net charge density along the separatrix. The asymmetry of the plasma density or magnetic field or both across the current sheet will largely increase the magnitude of the electric field and net charge. The results indicate that the asymmetry of the magnetic field is more effective in producing larger electric field and charge density. The electric field and net charge are always much larger in the low density or/and high magnetic field side than those in the high density or/and low magnetic field side. Both the electric field and net charge density are linearly dependent on the ratios of the plasma density or the square of the magnetic field across the current sheet. For the case with both initial asymmetries of the magnetic field and density, rather large Hall electric field and charge density are generated.

  9. Electric-field-enhanced condensation on superhydrophobic nanostructured surfaces.

    Science.gov (United States)

    Miljkovic, Nenad; Preston, Daniel J; Enright, Ryan; Wang, Evelyn N

    2013-12-23

    When condensed droplets coalesce on a superhydrophobic nanostructured surface, the resulting droplet can jump due to the conversion of excess surface energy into kinetic energy. This phenomenon has been shown to enhance condensation heat transfer by up to 30% compared to state-of-the-art dropwise condensing surfaces. However, after the droplets jump away from the surface, the existence of the vapor flow toward the condensing surface increases the drag on the jumping droplets, which can lead to complete droplet reversal and return to the surface. This effect limits the possible heat transfer enhancement because larger droplets form upon droplet return to the surface, which impedes heat transfer until they can be either removed by jumping again or finally shedding via gravity. By characterizing individual droplet trajectories during condensation on superhydrophobic nanostructured copper oxide (CuO) surfaces, we show that this vapor flow entrainment dominates droplet motion for droplets smaller than R ≈ 30 μm at moderate heat fluxes (q″ > 2 W/cm(2)). Subsequently, we demonstrate electric-field-enhanced condensation, whereby an externally applied electric field prevents jumping droplet return. This concept leverages our recent insight that these droplets gain a net positive charge due to charge separation of the electric double layer at the hydrophobic coating. As a result, with scalable superhydrophobic CuO surfaces, we experimentally demonstrated a 50% higher overall condensation heat transfer coefficient compared to that on a jumping-droplet surface with no applied field for low supersaturations (condensation heat transfer enhancement but also offers avenues for improving the performance of self-cleaning and anti-icing surfaces as well as thermal diodes.

  10. Regulation of tissue repair and regeneration by electric fields

    Institute of Scientific and Technical Information of China (English)

    WANG En-tong; ZHAO Min

    2010-01-01

    Endogenous electric fields(Efs)have been detected at wounds and damaged tissues.The potential roles of Efs in tissue repair and regeneration have been an intriguing topic for centuries.Recent researches have provided significant insights into how naturally occurring Efs may participate in the control of tissue repair and regeneration.Applied Efs equivalent to the size of fields measured in vivo direct cell migration,cell proliferation and nerve sprouting at wounds.More remarkably,physiological Efs are a guidance cue that directs cell migration which overrides other well accepted directional signals including initial injury stimulation,wound void,contact inhibition release,population pressure and chemotaxis.Efs activate many intracellular signaling pathways in a directional manner.Modulation of endogenous wound Efs affects epithelial cell migration,cell proliferation,and nerve growth at cornea wounds in vivo.Electric stimulation is being tested clinically for the treatments of bone fracture,wound healing and spinal cord injury.Efs thus may represent a novel type of signaling paradigm in tissue repair and regeneration.Combination of the electric stimulation and other well understood biochemical regulatory mechanisms may offer powerful and effective therapies for tissue repair and regeneration.This review introduces experimental evidence for the existence of endogenous Efs and discusses their roles in tissue repair and regeneration.

  11. Optical activity of microemulsion induced by electric field and its tunable behaviors

    Institute of Scientific and Technical Information of China (English)

    ZHAO; Xiaopeng(赵晓鹏); ZHAO; Qian(赵乾); XIANG; Liqin(向礼琴)

    2003-01-01

    It has been shown that optical activity can occur in microemulsion under external electric field and rotation angle can also be tuned by the electric field. A set of microemulsions (water/Span80/transformer oil) with different water concentration were prepared and their optical activity was measured with the changes of applied electric field and θ, the angle between the electric vector of the incident linearly polarized light and the external electric field, using an automatic polarimeter. The experiments indicate that when none of the external electric field, water concentration and θ are zero, there is optical activity in microemulsions. For a given concentration, rotation angle ψ increases with electric field, and it firstly increases, passes through a maximum at C = C0,then monotonically decreases as C increases when electric field keeps constant. The relationship between the rotation angle and θ is also obtained. It is thought that the electric field-induced destroy of spatial symmetry of microemulsion is responsible for the optical activity of microemulsion.

  12. Applying Smart Grid Technology For Reducing Electric Energy Consumption

    Energy Technology Data Exchange (ETDEWEB)

    Hoffman, Roy

    2010-09-15

    In recent years the term 'Smart Grid' has become a widely used buzz word with respect to the operation of Electric Power Systems. One analysis has suggested that a Smart Grid could potentially reduce annual energy consumption in the USA by 56 to 203 billion kWh in 2030, corresponding to a 1.2 to 4.3% reduction in projected retail electricity sales in 2030. This paper discusses some of the smart grid technologies pertaining to the operation of electric power distribution networks.

  13. Measurements of the vertical atmospheric electric field and of the electrical conductivity with stratospheric balloons

    Science.gov (United States)

    Iversen, I. B.; Madsen, M. M.; Dangelo, N.

    1985-01-01

    Measurements of the atmospheric (vertical) electric field with balloons in the stratosphere are reported. The atmospheric electrical conductivity is also measured and the current density inferred. The average vertical current shows the expected variation with universal time and is also seen to be influenced by external (magnetospheric) electric fields.

  14. Measurement of electric fields in the H-1NF heliac

    International Nuclear Information System (INIS)

    There are a number of laser induced fluorescence techniques which can be used to measure internal plasma electric fields. It is planned to use a technique based on Stark mixing of energy levels in a supersonic beam containing metastable helium atoms to measure radial electric fields in H-1NF. Enhanced values of radial electric field are associated with improved confinement modes in H-1NF and other magnetically confined plasmas

  15. Electric field induced bacterial flocculation of Enteroaggregative Escherichia coli 042

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Aloke [ORNL; Mortensen, Ninell P [ORNL; Mukherjee, Partha P [ORNL; Retterer, Scott T [ORNL; Doktycz, Mitchel John [ORNL

    2011-01-01

    A response of the aggregation dynamics of enteroaggregative Escherichia coli under low magnitude steady and oscillating electric fields is presented. The presence of uniform electric fields hampered microbial adhesion and biofilm formation on a transverse glass surface, but instead promoted the formation of flocs. Extremely heterogeneous distribution of live and dead cells was observed among the flocs. Moreover, floc formation was largely observed to be independent of the frequency of alternating electric fields.

  16. Effects of aging in electric field on 2024 alloy

    Institute of Scientific and Technical Information of China (English)

    王秀芳; 孙东立; 武高辉; 王美玲

    2002-01-01

    The effect of heat treatment in an electric field on micro-plastic deformation characteristics of 2024 Al alloy was investigated.The mechanism of aging in an electric field affecting the micro-plastic deformation behavior was preliminarily discussed.The results show that the resistance to micro-plastic deformation of the alloy can be greatly increased by aging in an electric field.Aging temperature,aging time and electric field strength are selected by adopting the orthogonal design method and the optimum technological parameters are obtained.

  17. Linear electric field time-of-flight ion mass spectrometer

    Science.gov (United States)

    Funsten, Herbert O.; Feldman, William C.

    2008-06-10

    A linear electric field ion mass spectrometer having an evacuated enclosure with means for generating a linear electric field located in the evacuated enclosure and means for injecting a sample material into the linear electric field. A source of pulsed ionizing radiation injects ionizing radiation into the linear electric field to ionize atoms or molecules of the sample material, and timing means determine the time elapsed between ionization of atoms or molecules and arrival of an ion out of the ionized atoms or molecules at a predetermined position.

  18. Moving antiphase boundaries using an external electric field

    Energy Technology Data Exchange (ETDEWEB)

    Vaideeswaran, Kaushik, E-mail: kaushik.vaideeswaran@alumni.epfl.ch; Shapovalov, Konstantin; Yudin, Petr V.; Setter, Nava [Ceramics Laboratory, Swiss Federal Institute of Technology (EPFL), CH-1015 Lausanne (Switzerland); Tagantsev, Alexander K. [Ceramics Laboratory, Swiss Federal Institute of Technology (EPFL), CH-1015 Lausanne (Switzerland); Ferroics Laboratory, Ioffe Physical Technical Institute, 194021 St. Petersburg (Russian Federation)

    2015-11-09

    Antiphase boundaries (APBs) are unique domain walls that may demonstrate switchable polarization in otherwise non-ferroelectric materials such as SrTiO{sub 3} and PbZrO{sub 3}. The current study explores the possibility of displacing such domain walls at the nanoscale. We suggest the possibility of manipulating APBs using the inhomogeneous electric field of an Atomic Force Microscopy (AFM) tip with an applied voltage placed in their proximity. The displacement is studied as a function of applied voltage, film thickness, and initial separation of the AFM tip from the APB. It is established, for example, that for films with thickness of 15 nm, an APB may be attracted under the tip with a voltage of 25 V from initial separation of 30 nm. We have also demonstrated that the displacement is appreciably retained after the voltage is removed, rendering it favorable for potential applications.

  19. Study of thermoelectric systems applied to electric power generation

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, A.; Vian, J.G.; Astrain, D.; Martinez, A. [Dpto. Ingenieria Mecanica, Energetica y de Materiales, Universidad Publica de Navarra, Pamplona (Spain)

    2009-05-15

    A computational model has been developed in order to simulate the thermal and electric behavior of thermoelectric generators. This model solves the nonlinear system of equations of the thermoelectric and heat transfer equations. The inputs of the program are the thermoelectric parameters as a function of temperature and the boundary conditions, (room temperature and residual heat flux). The outputs are the temperature values of all the elements forming the thermoelectric generator, (performance, electric power, voltage and electric current generated). The model solves the equation system using the finite difference method and semi-empirical expressions for the convection coefficients. A thermoelectric electric power generation test bench has been built in order to validate and determine the accuracy of the computational model, which maximum error is lower than 5%. The objective of this study is to create a design tool that allows us to solve the system of equations involved in the electric generation process without needing to impose boundary conditions that are not known in the design phase, such as the temperature of the Peltier modules. With the computational model, we study the influence of the heat flux supplied as well as the room temperature on the electric power generated. (author)

  20. Bilayer molecular assembly at a solid/liquid interface as triggered by a mild electric field.

    Science.gov (United States)

    Zheng, Qing-Na; Liu, Xuan-He; Liu, Xing-Rui; Chen, Ting; Yan, Hui-Juan; Zhong, Yu-Wu; Wang, Dong; Wan, Li-Jun

    2014-12-01

    The construction of a spatially defined assembly of molecular building blocks, especially in the vertical direction, presents a great challenge for surface molecular engineering. Herein, we demonstrate that an electric field applied between an STM tip and a substrate triggered the formation of a bilayer structure at the solid-liquid interface. In contrast to the typical high electric-field strength (10(9)  V m(-1) ) used to induce structural transitions in supramolecular assemblies, a mild electric field (10(5)  V m(-1) ) triggered the formation of a bilayer structure of a polar molecule on top of a nanoporous network of trimesic acid on graphite. The bilayer structure was transformed into a monolayer kagome structure by changing the polarity of the electric field. This tailored formation and large-scale phase transformation of a molecular assembly in the perpendicular dimension by a mild electric field opens perspectives for the manipulation of surface molecular nanoarchitectures.

  1. State-Space Based Approach to Particle Creation in Spatially Uniform Electric Fields

    CERN Document Server

    Dolby, C E; Dolby, Carl E.; Gull, Stephen F.

    2001-01-01

    Our formalism described recently in (Dolby et al, hep-th/0103228) is applied to the study of particle creation in spatially uniform electric fields, concentrating on the cases of a time-invariant electric field and a so-called `adiabatic' electric field. Several problems are resolved by incorporating the `Bogoliubov coefficient' approach and the `tunnelling' approaches into a single consistent, gauge invariant formulation. The value of a time-dependent particle interpretation is demonstrated by presenting a coherent account of the time-development of the particle creation process, in which the particles are created with small momentum (in the frame of the electric field) and are then accelerated by the electric field to make up the `bulge' of created particles predicted by asymptotic calculations. An initial state comprising one particle is also considered, and its evolution is described as being the sum of two contributions: the `sea of current' produced by the evolved vacuum, and the extra current arising f...

  2. High electric field development for the SNS nEDM Experiment

    CERN Document Server

    Ito, T M; Clayton, S M; Crawford, C; Currie, S A; Griffith, W C; Ramsey, J C; Roberts, A L; Schmid, R; Seidel, G M; Wagner, D; Yao, W

    2014-01-01

    A new experiment to search for the permanent electric dipole moment of the neutron is being developed for installation at the Spallation Neutron Source at Oak Ridge National Laboratory. This experiment will be performed in liquid helium at ? 0:4 K and requires a large electric field (E ~ 75 kV/cm) to be applied in liquid helium. We have constructed a new HV test apparatus to study electric breakdown in liquid helium. Initial results demonstrated that it is possible to apply fields exceeding 100 kV/cm in a 1 cm gap between two electropolished stainless steel electrodes12 cm in diameter for a wide range of pressures.

  3. Stress due to Electric and Magnetic fields in Viscoelastic Fluids

    CERN Document Server

    Joshi, Amey

    2013-01-01

    A clear understanding of body force densities due to external electromagnetic fields is necessary to study flow and deformation of materials exposed to the fields. In this paper, we derive an expression for stress in continua with viscous and elastic properties in presence of external, static electric or magnetic fluids. Our derivation follows from fundamental thermodynamic principles. We demonstrate the soundness of our results by showing that they reduce to known expressions for Newtonian fluids and elastic solids. We point out the extra care to be taken while applying these techniques to permanently polarized or magnetized materials and derive an expression for stress in a ferro-fluid. Lastly, we derive expressions for ponderomotive forces in several situations of interest to fluid dynamics and rheology.

  4. Surface electric fields for North America during historical geomagnetic storms

    Science.gov (United States)

    Wei, Lisa H.; Homeier, Nicole; Gannon, Jennifer L.

    2013-08-01

    To better understand the impact of geomagnetic disturbances on the electric grid, we recreate surface electric fields from two historical geomagnetic storms—the 1989 "Quebec" storm and the 2003 "Halloween" storms. Using the Spherical Elementary Current Systems method, we interpolate sparsely distributed magnetometer data across North America. We find good agreement between the measured and interpolated data, with larger RMS deviations at higher latitudes corresponding to larger magnetic field variations. The interpolated magnetic field data are combined with surface impedances for 25 unique physiographic regions from the United States Geological Survey and literature to estimate the horizontal, orthogonal surface electric fields in 1 min time steps. The induced horizontal electric field strongly depends on the local surface impedance, resulting in surprisingly strong electric field amplitudes along the Atlantic and Gulf Coast. The relative peak electric field amplitude of each physiographic region, normalized to the value in the Interior Plains region, varies by a factor of 2 for different input magnetic field time series. The order of peak electric field amplitudes (largest to smallest), however, does not depend much on the input. These results suggest that regions at lower magnetic latitudes with high ground resistivities are also at risk from the effect of geomagnetically induced currents. The historical electric field time series are useful for estimating the flow of the induced currents through long transmission lines to study power flow and grid stability during geomagnetic disturbances.

  5. Surface electric fields for North America during historical geomagnetic storms

    Science.gov (United States)

    Wei, Lisa H.; Homeier, Nichole; Gannon, Jennifer L.

    2013-01-01

    To better understand the impact of geomagnetic disturbances on the electric grid, we recreate surface electric fields from two historical geomagnetic storms—the 1989 “Quebec” storm and the 2003 “Halloween” storms. Using the Spherical Elementary Current Systems method, we interpolate sparsely distributed magnetometer data across North America. We find good agreement between the measured and interpolated data, with larger RMS deviations at higher latitudes corresponding to larger magnetic field variations. The interpolated magnetic field data are combined with surface impedances for 25 unique physiographic regions from the United States Geological Survey and literature to estimate the horizontal, orthogonal surface electric fields in 1 min time steps. The induced horizontal electric field strongly depends on the local surface impedance, resulting in surprisingly strong electric field amplitudes along the Atlantic and Gulf Coast. The relative peak electric field amplitude of each physiographic region, normalized to the value in the Interior Plains region, varies by a factor of 2 for different input magnetic field time series. The order of peak electric field amplitudes (largest to smallest), however, does not depend much on the input. These results suggest that regions at lower magnetic latitudes with high ground resistivities are also at risk from the effect of geomagnetically induced currents. The historical electric field time series are useful for estimating the flow of the induced currents through long transmission lines to study power flow and grid stability during geomagnetic disturbances.

  6. Retrieving Storm Electric Fields From Aircraft Field Mill Data. Part I: Theory

    Science.gov (United States)

    Koshak, W. J.

    2005-01-01

    It is shown that the problem of retrieving storm electric fields from an aircraft instrumented with several electric field mill sensors can be expressed in terms of a standard Lagrange multiplier optimization problem. The method naturally removes aircraft charge from the retrieval process without having to use a high voltage stinger and linearly combined mill data values. It also allows a variety of user-supplied physical constraints (the so-called side constraints in the theory of Lagrange multipliers). Additionally, this paper introduces a novel way of performing the absolute calibration of an aircraft that has several benefits over conventional analyses. In the new approach, absolute calibration is completed by inspecting the time derivatives of mill and pitch data for a pitch down maneuver performed at high (greater than 1 km) altitude. In Part II of this study, the above methods are tested and then applied to complete a full calibration of a Citation aircraft.

  7. Retrieving Storm Electric Fields from Aircraft Field Mill Data. Part 1; Theory

    Science.gov (United States)

    Koshak, W. J.

    2006-01-01

    It is shown that the problem of retrieving storm electric fields from an aircraft instrumented with several electric field mill sensors can be expressed in terms of a standard Lagrange multiplier optimization problem. The method naturally removes aircraft charge from the retrieval process without having to use a high voltage stinger and linearly combined mill data values. It allows a variety of user-supplied physical constraints (the so-called side constraints in the theory of Lagrange multipliers) and also helps improve absolute calibration. Additionally, this paper introduces an alternate way of performing the absolute calibration of an aircraft that has some benefits over conventional analyses. It is accomplished by using the time derivatives of mill and pitch data for a pitch down maneuver performed at high (greater than 1 km) altitude. In Part II of this study, the above methods are tested and then applied to complete a full calibration of a Citation aircraft.

  8. Reversible Tuning of a Block Copolymer Nanostructure via Electric Fields

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, K. [Universitat Bayreuth; Schoberth, Heiko [University of Bayreuth; Ruppel, Markus A. [Universitat Bayreuth; Zettl, H [University of Bayreuth; Weiss, Thomas [European Synchrotron Radiation Facility (ESRF); Urban, Volker S [ORNL; Krausch, G [University of Bayreuth; Boker, A. [Universitat Bayreuth

    2007-01-01

    Block copolymers consisting of incompatible components self-assemble into microphase-separated domains yielding highly regular structures with characteristic length scales of the order of several tens of nanometres. Therefore, in the past decades, block copolymers have gained considerable potential for nanotechnological applications, such as in nanostructured networks and membranes, nanoparticle templates and high-density data storage media. However, the characteristic size of the resulting structures is usually determined by molecular parameters of the constituent polymer molecules and cannot easily be adjusted on demand. Here, we show that electric d.c. fields can be used to tune the characteristic spacing of a block-copolymer nanostructure with high accuracy by as much as 6% in a fully reversible way on a timescale in the range of several milliseconds. We discuss the influence of various physical parameters on the tuning process and study the time response of the nanostructure to the applied field. A tentative explanation of the observed effect is given on the basis of anisotropic polarizabilities and permanent dipole moments of the monomeric constituents. This electric-field-induced effect further enhances the high technological potential of block-copolymer-based soft-lithography applications.

  9. First Results from the Swarm Electric Field Instruments

    Science.gov (United States)

    Knudsen, David; EFI Team

    2014-05-01

    The Swarm Electric Field Instruments (EFIs) provide measurements of plasma density, ion flow velocity, and ion and electron temperature at a rate of 2 per second. Ion velocity and magnetic field measurements will be combined during Level-1b processing to produce vector electric field estimates, also at a rate of 2 per second. Ion flow and temperature are determined from 2-D ion distribution functions recorded by two CCD-based particle detectors known as Thermal Ion Imagers. Electron temperature and density measurements are generated by two Langmuir probes. Within three weeks following launch on Nov 22, full power was applied to all sensors; since then instruments on all three spacecraft have been operating nominally. This talk will highlight the capabilities of the EFIs, and will provide an overview of observations made throughout the commissioning and early science operations phases. Acknowledgements: The EFIs were developed and built by a consortium that includes COM DEV Canada, the University of Calgary, and the Swedish Institute for Space Physics in Uppsala. The Swarm EFI project is managed and funded by the European Space Agency with additional funding from the Canadian Space Agency.

  10. Educational application for visualization and analysis of electric field strength in multiple electrode electroporation

    OpenAIRE

    Mahnič-Kalamiza Samo; Kotnik Tadej; Miklavčič Damijan

    2015-01-01

    Abstract Background Electrochemotherapy is a local treatment that utilizes electric pulses in order to achieve local increase in cytotoxicity of some anticancer drugs. The success of this treatment is highly dependent on parameters such as tissue electrical properties, applied voltages and spatial relations in placement of electrodes that are used to establish a cell-permeabilizing electric field in target tissue. Non-thermal irreversible electroporation techniques for ablation of tissue depe...

  11. Measurement of electric fields and estimation of dielectric susceptibility

    Science.gov (United States)

    Nogi, Yasuyuki; Suzuki, Kiyomitsu; Ohkuma, Yasunori

    2013-05-01

    We describe a method of measuring the spatial structures of electric fields produced by charge distributions such as those on strip electrodes, small disk electrodes, and long double-plate electrodes. An electric-field sensor with high sensitivity to ac fields is fabricated for the measurement using a thin copper sheet. The reliability of the sensor is confirmed using a parallel-plate capacitor. The electric fields are oscillated at a frequency of 300 kHz to operate the electric-field sensor successfully. The structures of the measured fields coincide well with those of theoretical fields derived from Coulomb's law. When a dielectric is inserted in an electric field, polarization charges appear on the surface of the dielectric and modify the electric field in empty space. We measure the modified field and confirm the well-known linear relation between the polarization of a dielectric and the electric field. Dielectric susceptibilities are estimated from the linear relation for four types of dielectric.

  12. Intracellular calcium during signal transduction in the lymphocyte is altered by ELF magnetic and electric fields

    Energy Technology Data Exchange (ETDEWEB)

    Liburdy, R.P. (Lawrence Berkeley Lab., CA (United States))

    1992-02-26

    Research has shown that ELF magnetic and electric fields alter calcium transport in rat thymic T-lymphocytes during signal transduction initiated by mitogen. Interestingly activated T-lymphocytes display a nonlinear dose-response for this basic field interaction which scales with the induced electric field in contrast to the applied magnetic field. Specialized multiring annular well cell culture plates based on Faraday's Law of Current Induction were used to demonstrate that the electric field associated with the magnetic field is the exposure metric of biological interest. The first real-time measurements of (Ca{sup 2+}){sub i} were recently presented and (Ca{sup 2+}){sub i} was shown to be altered by sinusoidal 60 Hz electric fields; magnetic fields that induced comparable electric fields yielded similar alterations in (Ca{sup 2+}){sub i}. The author now presents evidence that both parameters, (Ca{sup 2+}){sub i} and calcium transport, are altered by ELF fields during calcium signaling in thymocytes and scale with the induced electric field. In addition, (Ca{sup 2+}){sub i} studies have been conducted that provide evidence supporting the hypothesis that the mitogen-gated calcium channel present in the plasma cell membrane represents a specific site of interaction for ELF fields.

  13. Effective electric fields along realistic DTI-based neural trajectories for modelling the stimulation mechanisms of TMS

    NARCIS (Netherlands)

    De Geeter, N.; Crevecoeur, G.; Leemans, A.; Dupré, L.

    2015-01-01

    In transcranial magnetic stimulation (TMS), an applied alternating magnetic field induces an electric field in the brain that can interact with the neural system. It is generally assumed that this induced electric field is the crucial effect exciting a certain region of the brain. More specifically,

  14. Inner Magnetospheric Electric Fields Derived from IMAGE EUV

    Science.gov (United States)

    Gallagher, D. L.; Adrian, M. L.

    2007-01-01

    The local and global patterns of plasmaspheric plasma transport reflect the influence of electric fields imposed by all sources in the inner magnetosphere. Image sequences of thermal plasma G:istribution obtained from the IMAGE Mission Extreme Ultraviolet Imager can be used to derive plasma motions and, using a magnetic field model, the corresponding electric fields. These motions and fields directly reflect the dynamic coupling of injected plasmasheet plasma and the ionosphere, in addition to solar wind and atmospheric drivers. What is being learned about the morphology of inner magnetospheric electric fields during storm and quite conditions from this new empirical tool will be presented and discussed.

  15. Electric fields inside and outside an anisotropic dielectric sphere

    Institute of Scientific and Technical Information of China (English)

    Li Ying-Le; Wang Ming-Jun

    2009-01-01

    Analytical expressions of electric fields inside and outside an anisotropic dielectric sphere are presented by transforming an anisotropic medium into an isotropic one based on the multi-scale transformation of electromagnetic theory.The theoretical expressions are consistent with those in the literature. The inside electric field, the outside electric field and the angle between their directions are derived in detail. Numerical simulations show that the direction of the outside field influences the magnitude of the inside field, while the dielectric constant tensor greatly affects its direction.

  16. Magnetic field characteristics of electric bed-heating devices

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, B.W.; Davis, K.C.; Heimbigner, T.; Buschbom, R.L. [Pacific Northwest National Lab., Richland, WA (United States); Lee, G.M. [California State Department of Health Services, Berkeley, CA (United States); Yost, M.G. [Univ. of Washington School of Public Health, Seattle, WA (United States)

    1996-12-01

    Measurements of the flux density and spectra of magnetic fields (MFs) generated by several types of electric bed heaters (EBH) were made in order to characterize the MFs to which the fetus may be exposed in utero from the mother`s use of these devices. Data on MFs were gathered from more than 1,300 in-home and laboratory spot measurements. In-home measurements taken at seven different positions 10 cm from the EBHs determined that the mean flux density at the estimated position of the fetus relative to the device was 0.45 {micro}T (4.5 mG) for electric blankets and 0.20 {micro}T (2.0 mG) for electrically heated water beds. A rate-of-change (RC) metric applied to the nighttime segment of 24 h EMDEX-C personal-dosimeter measurements, which were taken next to the bed of volunteers, yielded an approximate fourfold to sixfold higher value for electric blanket users compared to water-bed heater users. These same data records yielded an approximate twofold difference for the same measurements when evaluated by the time-weighted-average (TWA) MF exposure metric. Performance of exposure meters was checked against standard fields generated in the laboratory, and studies of sources of variance in the in-home measurement protocols were carried out. Spectral measurements showed that the EBHs measured produced no appreciable high-frequency MFs. Data gathered during this work will be used in interpreting results from a component of the California Pregnancy Outcome Study, which evaluates the use of EBHs as a possible risk factor in miscarriage.

  17. Electric field driven plasmon dispersion in AlGaN/GaN high electron mobility transistors

    Science.gov (United States)

    Tan, Ren-Bing; Qin, Hua; Zhang, Xiao-Yu; Xu, Wen

    2013-11-01

    We present a theoretical study on the electric field driven plasmon dispersion of the two-dimensional electron gas (2DEG) in AlGaN/GaN high electron mobility transistors (HEMTs). By introducing a drifted Fermi—Dirac distribution, we calculate the transport properties of the 2DEG in the AlGaN/GaN interface by employing the balance-equation approach based on the Boltzmann equation. Then, the nonequilibrium Fermi—Dirac function is obtained by applying the calculated electron drift velocity and electron temperature. Under random phase approximation (RPA), the electric field driven plasmon dispersion is investigated. The calculated results indicate that the plasmon frequency is dominated by both the electric field E and the angle between wavevector q and electric field E. Importantly, the plasmon frequency could be tuned by the applied source—drain bias voltage besides the gate voltage (change of the electron density).

  18. Static and low frequency electric and magnetic fields

    International Nuclear Information System (INIS)

    The biological effects of exposure to low frequency electric and magnetic fields are reviewed with the objective of summarizing effects directly relevant to considerations of the health and safety of exposed people. Static and low frequency electric and magnetic fields may elicit biological reactions. Whether exposure to such fields may affect human health at field strengths present in everyday or occupational life is still unsettled. There is unsufficient knowledge to establish any dose concept relevant to health risk. 196 refs., 6 tabs

  19. Method for electric field and potential calculations in Hall plates

    OpenAIRE

    Raman, Johan; Rombouts, Pieter; Weyten, Ludo

    2013-01-01

    Electrostatic field problems occurring in Hall plates are difficult to solve, mainly because of a non-standard boundary condition defining an oblique angle of the electric field w.r.t. an isolating boundary. A new approach for solving Hall-related field problems is presented. Compared to prior approaches, the technique leads more easily to closed-form expressions for the electric field, and allows obtaining voltage-related Hall characteristics in numerically well conditioned forms.

  20. On the ionospheric coupling of auroral electric fields

    OpenAIRE

    G. T. Marklund

    2009-01-01

    The quasi-static coupling of high-altitude potential structures and electric fields to the ionosphere is discussed with particular focus on the downward field-aligned current (FAC) region. Results are presented from a preliminary analysis of a selection of electric field events observed by Cluster above the acceleration region. The degree of coupling is here estimated as the ratio between the magnetic field-aligned potential drop, ΔΦII, as inferred fro...

  1. Middle atmospheric electric fields over thunderstorms

    Science.gov (United States)

    Holzworth, Robert H.

    1992-01-01

    This grant has supported a variety of investigations all having to do with the external electrodynamics of thunderstorms. The grant was a continuation of work begun while the PI was at the Aerospace Corporation (under NASA Grant NAS6-3109) and the general line of investigation continues today under NASA Grants NAG5-685 and NAG6-111. This report will briefly identify the subject areas of the research and associated results. The period actually covered by the grant NAG5-604 included the following analysis and flights: (1) analysis of five successful balloon flights in 1980 and 1981 (under the predecessor NASA grant) in the stratosphere over thunderstorms; (2) development and flight of the Hy-wire tethered balloon system for direct measurement of the atmospheric potential to 250 kV (this involved multiple tethered balloon flight periods from 1981 through 1986 from several locations including Wallops Island, VA, Poker Flat and Ft. Greely, AK and Holloman AFB, NM.); (3) balloon flights in the stratosphere over thunderstorms to measure vector electric fields and associated parameters in 1986 (2 flights), 1987 (4 flights), and 1988 (2 flights); and (4) rocket-borne optical lightning flash detectors on two rocket flights (1987 and 1988) (the same detector design that was used for the balloon flights listed under #3). In summary this grant supported 8 stratospheric zero-pressure balloon flights, tethered aerostat flights every year between 1982-1985, instruments on 2 rockets, and analysis of data from 6 stratospheric flights in 1980/81.

  2. Gastric applications of electrical field stimulation.

    LENUS (Irish Health Repository)

    Hogan, Aisling M

    2012-02-01

    Advances in clinical applications of electricity have been vast since the launch of Hayman\\'s first cardiac pacemaker more than 70 years ago. Gastric electrical stimulation devices have been recently licensed for treatment of gastroparesis and preliminary studies examining their potential for use in refractory obesity yield promising results.

  3. AC electric field induced droplet deformation in a microfluidic T-junction.

    Science.gov (United States)

    Xi, Heng-Dong; Guo, Wei; Leniart, Michael; Chong, Zhuang Zhi; Tan, Say Hwa

    2016-08-01

    We present for the first time an experimental study on the droplet deformation induced by an AC electric field in droplet-based microfluidics. It is found that the deformation of the droplets becomes stronger with increasing electric field intensity and frequency. The measured electric field intensity dependence of the droplet deformation is consistent with an early theoretical prediction for stationary droplets. We also proposed a simple equivalent circuit model to account for the frequency dependence of the droplet deformation. The model well explains our experimental observations. In addition, we found that the droplets can be deformed repeatedly by applying an amplitude modulation (AM) signal. PMID:27173587

  4. Engineering the electronic structure and band gap of boron nitride nanoribbon via external electric field

    Science.gov (United States)

    Chegel, Raad

    2016-06-01

    By using the third nearest neighbor modified tight binding (3NN-TB) method, the electronic structure and band gap of BNNRs under transverse electric fields are explored. The band gap of the BNNRs has a decreasing with increasing the intensity of the applied electric field, independent on the ribbon edge types. Furthermore, an analytic model for the dependence of the band gap in armchair and zigzag BNNRs on the electric field is proposed. The reduction of E g is similar for some N a armchair and N z zigzag BNNRs independent of their edges.

  5. Possible effects of external electrical fields on the corrosion of copper in bentonite

    Energy Technology Data Exchange (ETDEWEB)

    Taxen, Claes (Swerea KIMAB (Sweden))

    2011-12-15

    External potentials that develop across a repository may interact with the copper canister. A study was undertaken to investigate the potential corrosion effects of voltage differences in a repository. A set of experiments was performed to study the tendency of copper in bentonite to corrode under influence of an externally applied electrical field. A model study was made to estimate possible corrosion effects of an external electrical field on a full-scale canister in the KBS-3 concept. The interaction between the repository represented by a copper canister in bentonite, and an external electrical field is illustrated with an example

  6. Rocket borne instrument to measure electric fields inside electrified clouds

    Science.gov (United States)

    Ruhnke, L. H. (Inventor)

    1973-01-01

    An apparatus for measuring the electric field in the atmosphere which includes a pair of sensors carried on a rocket for sensing the voltages in the atmosphere being measured is described. One of the sensors is an elongated probe with a fine point which causes a corona current to be produced as it passes through the electric field. An electric circuit is coupled between the probe and the other sensor and includes a high ohm resistor which linearizes the relationship between the corona current and the electric field being measured. A relaxation oscillator and transmitter are provided for generating and transmitting an electric signal having a frequency corresponding to the magnitude of the electric field.

  7. Conformational dynamics and aggregation behavior of piezoelectric diphenylalanine peptides in an external electric field

    OpenAIRE

    Kelly, Catherine M; Northey, Thomas; Ryan, Kate; Brooks, Bernard R.; Kholkin, Andrei; Rodriguez, Brian J.; Buchete, Nicolae-Viorel

    2014-01-01

    Aromatic peptides such as diphenylalanine (FF) have the characteristic capacity to self-assemble into ordered nanostructures such as peptide nanotubes, which are biocompatible, thermally and chemically stable, and have strong piezoelectric activity and high mechanical strength. The physical properties of FF aggregates open up a variety of potential biomedical applications. Electric fields are commonly applied to align FF nanotubes, yet little is known about the effect of the electric field on...

  8. Visualization of electric field in ion conductive oxides using neutron computed tomography

    International Nuclear Information System (INIS)

    Neutron computed tomography was applied to visualize of electric field in the spinel-type lithium conductive oxide Li1.33Ti1.67O4. Distribution of lithium ion in the specimen was able to be visualized by this method. Considering the distribution of lithium ion inserted through point interface, the electric field formed in the specimen appeared to be similar to that of metallic conductor. (author)

  9. Experimental Study of Pool Boiling Heat Transfer Enhancement with R123 under Non Uniform Electric Field

    Directory of Open Access Journals (Sweden)

    Hongling Yu

    2013-02-01

    Full Text Available Experimental investigations are carried out to study the effect of a non uniform electric field on the boiling heat transfer. The study has found that the heat transfer coefficient increases as the electric field strength increases. Enhanced coefficient decreases with heat flux increases and finally reaches a steady value. When the heat flux is small, high voltage has a better enhancement effect. The Onset of Nucleate Boiling (ONB undergoes a larger increase by applying a high voltage.

  10. GUIDING OF PLASMA BY ELECTRIC FIELD AND MAGNETIC FIELD

    Institute of Scientific and Technical Information of China (English)

    ZHANG TAO; HOU JUN-DA; TANG BAO-YIN; P. K. CHU; I. G. BROWN

    2001-01-01

    The relationship between the transported ion current and the cathodic arc current is determined in a vacuum arc plasma source equipped with a curved magnetic filter. Our results suggest that the outer and inner walls of the duct interact with the plasma independently. The duct magnetic field is a critical factor of the plasma output. The duct transport efficiency is to maximize at a value of bias plate voltage in the range +10 V to +20 V, and independent (within our limit of measurement) of the magnetic field strength in the duct. The plasma flux is composed of two components:a diffusion flux in the transverse direction due to particle collisions, and a drift flux due to the ion inertia. The inner wall of the magnetic duct sees only the diffusion flux while the outer wall receives both fluxes. Thus, applying a positive potential to the outer duct wall can reflect the ions and increase the output current. Our experimental data also show that biasing both sides of the duct is more effective than biasing the outer wall alone.

  11. High School Students' Representations and Understandings of Electric Fields

    Science.gov (United States)

    Cao, Ying; Brizuela, Bárbara M.

    2016-01-01

    This study investigates the representations and understandings of electric fields expressed by Chinese high school students 15 to 16 years old who have not received high school level physics instruction. The physics education research literature has reported students' conceptions of electric fields post-instruction as indicated by students'…

  12. The effect of normal electric field on the evolution of immiscible Rayleigh-Taylor instability

    Science.gov (United States)

    Tofighi, Nima; Ozbulut, Murat; Feng, James J.; Yildiz, Mehmet

    2016-04-01

    Manipulation of the Rayleigh-Taylor instability using an external electric field has been the subject of many studies. However, most of these studies are focused on early stages of the evolution. In this work, the long-term evolution of the instability is investigated, focusing on the forces acting on the interface between the two fluids. To this end, numerical simulations are carried out at various electric permittivity and conductivity ratios as well as electric field intensities using Smoothed Particle Hydrodynamics method. The electric field is applied in parallel to gravity to maintain unstable evolution. The results show that increasing top-to-bottom permittivity ratio increases the rising velocity of the bubble while hindering the spike descent. The opposite trend is observed for increasing top-to-bottom conductivity ratio. These effects are amplified at larger electric field intensities, resulting in narrower structures as the response to the excitation is non-uniform along the interface.

  13. The effect of normal electric field on the evolution of immiscible Rayleigh-Taylor instability

    Science.gov (United States)

    Tofighi, Nima; Ozbulut, Murat; Feng, James J.; Yildiz, Mehmet

    2016-10-01

    Manipulation of the Rayleigh-Taylor instability using an external electric field has been the subject of many studies. However, most of these studies are focused on early stages of the evolution. In this work, the long-term evolution of the instability is investigated, focusing on the forces acting on the interface between the two fluids. To this end, numerical simulations are carried out at various electric permittivity and conductivity ratios as well as electric field intensities using Smoothed Particle Hydrodynamics method. The electric field is applied in parallel to gravity to maintain unstable evolution. The results show that increasing top-to-bottom permittivity ratio increases the rising velocity of the bubble while hindering the spike descent. The opposite trend is observed for increasing top-to-bottom conductivity ratio. These effects are amplified at larger electric field intensities, resulting in narrower structures as the response to the excitation is non-uniform along the interface.

  14. Electric-field-driven alignment of chiral conductive polymer thin films.

    Science.gov (United States)

    Tassinari, Francesco; Mathew, Shinto P; Fontanesi, Claudio; Schenetti, Luisa; Naaman, Ron

    2014-04-29

    We investigated the effect of an electric field on the alignment and structural properties of thin films of a chiral polybithiophene-based conductive polymer, functionalized with a protected l-cysteine amino acid. Thin films were obtained by exploiting both drop-casting and spin-coating procedures. The electric properties, the polarized Raman spectrum, the UV-vis spectrum, and the CD spectra were measured as a function of the electric field intensity applied during film formation. It was found that beyond the enhancement of the conductivity observed when the electric field aligns the polymer, the electric field significantly affects the chiral properties and the effect depends on the method of deposition. PMID:24731141

  15. Defect agglomeration in ferroelectric ceramics under cyclic electric field

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The agglomeration of point defects in ferroelectric ceramics could be driven by repeated domain switching under cyclic electric field. The evolution equation of pore concentration under cyclic electric field is derived, with the help of a relation between the pore concentration and the extent of pore agglomeration. The results of the simulation agree quantitatively with the experimental data. An integrated framework about the mechanisms of electrically induced fatigue is proposed, which links the mechanisms at different scales.

  16. Effect of AC electric fields on the stabilization of premixed bunsen flames

    KAUST Repository

    Kim, Minkuk

    2011-01-01

    The stabilization characteristics of laminar premixed bunsen flames have been investigated experimentally for stoichiometric methane-air mixture by applying AC voltage to the nozzle with the single-electrode configuration. The detachment velocity either at blowoff or partial-detachment has been measured by varying the applied voltage and frequency of AC. The result showed that the detachment velocity increased with the applied AC electric fields, such that the flame could be nozzle-attached even over five times of the blowoff velocity without having electric fields. There existed four distinct regimes depending on applied AC voltage and frequency. In the low voltage regime, the threshold condition of AC electric fields was identified, below which the effect of electric fields on the detachment velocity is minimal. In the moderate voltage regime, the flame base oscillated with the frequency synchronized to AC frequency and the detachment velocity increased linearly with the applied AC voltage and nonlinearly with the frequency. In the high voltage regime, two different sub-regimes depending on AC frequency were observed. For relatively low frequency, the flame base oscillated with the applied AC frequency together with the half frequency and the variation of the detachment velocity was insensitive to the applied voltage. For relatively high frequency, the stabilization of the flame was significantly affected by the generation of streamers and the detachment velocity decreased with the applied voltage. © 2010 Published by Elsevier Inc. on behalf of The Combustion Institute. All rights reserved.

  17. Lower Atmospheric Electric Field due to Cloud Charge Distribution

    Science.gov (United States)

    Paul, Suman; Haldar, Dilip kumar; Sundar De, Syam; Ghosh, Abhijit; Hazra, Pranab; Bandyopadhyay, Bijoy

    2016-07-01

    The distributions of electric charge in the electrified clouds introduce important effects in the ionosphere and into the region between the ionosphere and the Earth. The electrical properties of the medium are changed greatly between thundercloud altitudes and the magnetosphere. A model for the penetration of DC thundercloud electric field between the Earth's upper and lower atmosphere has been presented here. The model deals with the electromagnetic responses of the atmosphere simulated through Maxwell's equations together with a time-varying source charge distribution. The modified ellipsoidal-Gaussian profile has been taken for the charge distribution of the electrified cloud. The conductivity profile of the medium is taken to be isotropic below 70 km height and anisotropic above 70 km. The Earth's surface is considered to be perfectly conducting. A general form of equation representing the thundercloud electric field component is deduced. In spite of assumptions for axial symmetry of thundercloud charge distribution considered in the model, the results are obtained giving the electric field variation in the upper atmosphere. The vertical component of the electric field would relate the global electric circuit while the radial component showed the electrical coupling between the lower atmosphere and the ionized Earth's environment. The variations of the values of field components for different heights as well as Maxwell's current have been evaluated. Coupling between the troposphere and the ionosphere is critically dependent on the height variations of electrical conductivity. Field-aligned electron density irregularities in the ionosphere may be investigated through the present analyses.

  18. The effect of electric and magnetic fields on the operation of a photovoltaic cell

    Energy Technology Data Exchange (ETDEWEB)

    Erel, Serafettin [Department of Physics, Faculty of Science and Letters, Kirikkale University, 71450 Yahsihan, Kirikkale (Turkey)

    2002-02-01

    In this work, we have investigated the effects of electric and magnetic fields on the operation of a CdS/CuInSe{sub 2} photovoltaic cell. Various electric field intensities changing from 0 to 35000V{sub dc}/m, were applied to the sample while it was irradiated by a He-Ne laser with a wavelength {lambda}=670nm. As a result, the typical values for the open circuit voltage of the photovoltaic cell significantly changed with various intensities of the electric field E{sub dc}. We also applied magnetic fields varying from 0.003 to 0.079T using a solenoid with an inductance of 10.55mH and the response of the sample was observed. In the third step of the experiment, instead of the laser beam, various intensities of white light of 50, 100,150 and also 250lux were utilised. 250lux was measured to be equivalent to the radiation power of He-Ne laser beam on the surface of the photovoltaic cell. The effect of electric fields from 0 up to 3x10{sup 5}V{sub dc} was applied and some significant experimental results were obtained. As a result of the illumination of the photovoltaic cell by the stimulated and spontaneous light emission sources under the effect of various intensities of electric field E{sub dc}, different electrical behaviours were observed.

  19. Charging gold nanoparticles in ZnO by electric fields

    International Nuclear Information System (INIS)

    Controlling the plasmon resonance frequency of metal nanostructures holds promise for both fundamental and applied research in optics. The plasmon resonance frequency depends on the number of free electrons in the metal. By adding or removing electrons to a metal nano-object, the plasmon resonance frequency shifts. In this study we indirectly change the number of free electrons in gold nanoparticles by applying an electrical potential difference over a heterostructure consisting of a ZnO layer with embedded gold nanoparticles. The potential difference induces shifts of defect energy levels in the ZnO by the electric field. This results in an exchange of electrons between particles and matrix which in turn modifies the gold nanoparticle plasmon properties. The positive charge shifts the ZnO optical absorption peak from 377 nm to 386 nm and shifts the nanoparticle plasmon from 549 nm to 542 nm. This electro-optical effect is a promising way to obtain fast optical switching in a solid state composition. (paper)

  20. Mechanical Decoupling Algorithm Applied to Electric Drive Test Bed

    OpenAIRE

    2014-01-01

    New approach and analysis are proposed in this paper to enhance the steady and rapidity of the electric drive test bed. Based on a basic drive motor dynamometer system (DMDS) test bed, detailed mathematical model and process control are established and analyzed. Relative gain array (RGA) method and diagonal matrix method are used to analyze the mechanical coupling caused by mechanical connection on the DMDS test bed, and the structure and algorithm of dynamic decoupling are proposed. Simulati...

  1. Applying a Splitting Technique to Estimate Electrical Grid Reliability

    OpenAIRE

    Wadman, Wander; Crommelin, Daan; Frank, Jason; Pasupathy, R.; Kim, S.-H.; Tolk, A.; Hill, R; Kuhl, M.E.

    2013-01-01

    As intermittent renewable energy penetrates electrical power grids more and more, assessing grid reliability is of increasing concern for grid operators. Monte Carlo simulation is a robust and popular technique to estimate indices for grid reliability, but the involved computational intensity may be too high for typical reliability analyses. We show that various reliability indices can be expressed as expectations depending on the rare event probability of a so-called power curtailment, and e...

  2. Infrared optical activity: electric field approaches in time domain.

    Science.gov (United States)

    Rhee, Hanju; Choi, Jun-Ho; Cho, Minhaeng

    2010-12-21

    Vibrational circular dichroism (VCD) spectroscopy provides detailed information about the absolute configurations of chiral molecules including biomolecules and synthetic drugs. This method is the infrared (IR) analogue of the more popular electronic CD spectroscopy that uses the ultraviolet and visible ranges of the electromagnetic spectrum. Because conventional electronic CD spectroscopy measures the difference in signal intensity, problems such as weak signal and low time-resolution can limit its utility. To overcome the difficulties associated with that approach, we have recently developed femtosecond IR optical activity (IOA) spectrometry, which directly measures the IOA free-induction-decay (FID), the impulsive chiroptical IR response that occurs over time. In this Account, we review the time-domain electric field measurement and calculation methods used to simultaneously characterize VCD and related vibrational optical rotatory dispersion (VORD) spectra. Although conventional methods measure the electric field intensity, this vibrational technique is based on a direct phase-and-amplitude measurement of the electric field of the chiroptical signal over time. This method uses a cross-polarization analyzer to carry out heterodyned spectral interferometry. The cross-polarization scheme enables us to selectively remove the achiral background signal, which is the dominant noise component present in differential intensity measurement techniques. Because we can detect the IOA FID signal in a phase-amplitude-sensitive manner, we can directly characterize the time-dependent electric dipole/magnetic dipole response function and the complex chiral susceptibility that contain information about the angular oscillations of charged particles. These parameters yield information about the VCD and VORD spectra. In parallel with such experimental developments, we have also calculated the IOA FID signal and the resulting VCD spectrum. These simulations use a quantum mechanical

  3. Vertical electric field stimulated neural cell functionality on porous amorphous carbon electrodes.

    Science.gov (United States)

    Jain, Shilpee; Sharma, Ashutosh; Basu, Bikramjit

    2013-12-01

    We demonstrate the efficacy of amorphous macroporous carbon substrates as electrodes to support neuronal cell proliferation and differentiation in electric field mediated culture conditions. The electric field was applied perpendicular to carbon substrate electrode, while growing mouse neuroblastoma (N2a) cells in vitro. The placement of the second electrode outside of the cell culture medium allows the investigation of cell response to electric field without the concurrent complexities of submerged electrodes such as potentially toxic electrode reactions, electro-kinetic flows and charge transfer (electrical current) in the cell medium. The macroporous carbon electrodes are uniquely characterized by a higher specific charge storage capacity (0.2 mC/cm(2)) and low impedance (3.3 kΩ at 1 kHz). The optimal window of electric field stimulation for better cell viability and neurite outgrowth is established. When a uniform or a gradient electric field was applied perpendicular to the amorphous carbon substrate, it was found that the N2a cell viability and neurite length were higher at low electric field strengths (≤ 2.5 V/cm) compared to that measured without an applied field (0 V/cm). While the cell viability was assessed by two complementary biochemical assays (MTT and LDH), the differentiation was studied by indirect immunostaining. Overall, the results of the present study unambiguously establish the uniform/gradient vertical electric field based culture protocol to either enhance or to restrict neurite outgrowth respectively at lower or higher field strengths, when neuroblastoma cells are cultured on porous glassy carbon electrodes having a desired combination of electrochemical properties.

  4. Effects of geomagnetic activity on the mesospheric electric fields

    Directory of Open Access Journals (Sweden)

    A. M. Zadorozhny

    Full Text Available The results of three series of rocket measurements of mesospheric electric fields carried out under different geomagnetic conditions at polar and high middle latitudes are analysed. The measurements show a clear dependence of the vertical electric fields on geomagnetic activity at polar and high middle latitudes. The vertical electric fields in the lower mesosphere increase with the increase of geomagnetic indexes Kp and ∑Kp. The simultaneous increase of the vertical electric field strength and ion conductivity was observed in the mesosphere during geomagnetic disturbances. This striking phenomenon was displayed most clearly during the solar proton events of October, 1989 accompanied by very strong geomagnetic storm (Kp=8+. A possible mechanism of generation of the vertical electric fields in the mesosphere caused by gravitational sedimentation of charged aerosol particles is discussed. Simultaneous existence in the mesosphere of both the negative and positive multiply charged aerosol particles of different sizes is assumed for explanation of the observed V/m vertical electric fields and their behaviour under geomagnetically disturbed conditions.

    Keywords. Atmospheric composition and structure (aerosols and particles · Ionosphere (electric fields and currents · Meteorology and atmospheric dynamics (atmospheric electricity

  5. Some effects of favorable and adverse electric fields on pool boiling in dielectric fluids

    International Nuclear Information System (INIS)

    The effects of the application of an electric field on pool boiling in dielectric fluids were studied in this work.Two different geometries were used: one which is favorable to the bubble detachment (favorable electric field) and other which attract the bubbles toward the heater (adverse electric field).In the favorable electric field experiments, the void fraction and impact rate were calculated from the measured indicator function.Those parameters were obtained varying the probe-heater distance and the power to the heater.The results show a reduction of the void fraction with increasing applied voltage, probably caused by the combination of the dielectrophoretic force and a smaller bubble size due to the electric field application. Also, the impact rate decreases when a voltage is applied and the heat fluxes are close to the critical heat flux (CHF).On the other hand, the impact rate increases with voltage for moderate heat fluxes.Another interesting result is the approximately exponential decay of the void fraction and impact rate with the distance to the heater. Both the void fraction and the impact rate grow with heat flux if the heat fluxes are moderate, with or without applied voltage.For highest heat fluxes the void fraction still grows with heat flux if there are no applied electric fields while decreases with heat flux when there is an applied voltage. Similar behavior is observed in the impact rate.The boiling regimes was measured with adverse electric fields using two techniques.The heat transfer in the nucleate boiling regime was measured on an electrically powered heater.The results in these experiments show a reduction in the CHF of 10 % for saturation conditions and 10 kV of applied voltage, and a reduction of up to 40 % for 20 oC of liquid subcooling.The boiling curve corresponding to the transition and film boiling was performed with quenching experiments.An increase in the heat flux was achieved when an electric field was applied in spite of the

  6. Enhanced proton acceleration in an applied longitudinal magnetic field

    CERN Document Server

    Arefiev, Alexey; Fiksel, Gennady

    2016-01-01

    Using two-dimensional particle-in-cell simulations, we examine how an externally applied strong magnetic impacts proton acceleration in laser-irradiated solid-density targets. We find that a kT-level external magnetic field can sufficiently inhibit transverse transport of hot electrons in a flat laser-irradiated target. While the electron heating by the laser remains mostly unaffected, the reduced electron transport during proton acceleration leads to an enhancement of maximum proton energies and the overall number of energetic protons. The resulting proton beam is much better collimated compared to a beam generated without applying a kT-level magnetic field. A factor of three enhancement of the laser energy conversion efficiency into multi-MeV protons is another effect of the magnetic field. The required kT magnetic fields are becoming feasible due to a significant progress that has been made in generating magnetic fields with laser-driven coils using ns-long laser pulses. The predicted improved characterist...

  7. Enhancement factors for local electric fields in inhomogeneous media

    International Nuclear Information System (INIS)

    The microstructure of dielectric films provides a significant influence on the electric field distribution in these materials. In this paper, we focus on the relationship between the electric field distribution and organization of film constituents. Using our self-consistent determination of the local electric field in inhomogeneous media, we have shown that enhanced fields can result from columnar microstructures such as typically generated by CVD-type fabrication processes, and low dielectric components in optical coatings. In addition to the microstructural enhancement, a surface specific enhancement due to presence of low dielectric components is observed

  8. Deformation of a nearly hemispherical conducting drop due to an electric field: Theory and experiment

    Science.gov (United States)

    Corson, L. T.; Tsakonas, C.; Duffy, B. R.; Mottram, N. J.; Sage, I. C.; Brown, C. V.; Wilson, S. K.

    2014-12-01

    We consider, both theoretically and experimentally, the deformation due to an electric field of a pinned nearly hemispherical static sessile drop of an ionic fluid with a high conductivity resting on the lower substrate of a parallel-plate capacitor. Using both numerical and asymptotic approaches, we find solutions to the coupled electrostatic and augmented Young-Laplace equations which agree very well with the experimental results. Our asymptotic solution for the drop interface extends previous work in two ways, namely, to drops that have zero-field contact angles that are not exactly π/2 and to higher order in the applied electric field, and provides useful predictive equations for the changes in the height, contact angle, and pressure as functions of the zero-field contact angle, drop radius, surface tension, and applied electric field. The asymptotic solution requires some numerical computations, and so a surprisingly accurate approximate analytical asymptotic solution is also obtained.

  9. Effect of electric field, stress and environment on delayed fracture of a PZT-5 ferroelectric ceramic

    Institute of Scientific and Technical Information of China (English)

    WANG Yi; SU Yanjing; CHU Wuyang; QIAO Lijie

    2005-01-01

    The combined effect of electric and mechanical loading on fracture of a PZT-5 ferroelectric ceramic in silicone oil has been investigated using a single edge notched specimen. The results show that the fracture toughness and the threshold stress intensity factor of delayed fracture in silicone oil, i.e. stress corrosion cracking, decrease linearly with the increasing applied electric field, either positive or negative. For the PZT-5 ferroelectric ceramics, delayed fracture in silicone oil under sustained positive or negative field can occur, and the threshold field for delayed fracture under sustained positive or negative field decreases linearly with applied stress intensity factor. The combined effect of electric and mechanical loading on delayed fracture in silicone oil includes fieldenhancing delayed fracture under sustained load and stress-enhancing delayed fracture in silicone oil under sustained field.

  10. 60 Hz electric field changes the membrane potential during burst phase in pancreatic β-cells: in silico analysis.

    Science.gov (United States)

    Neves, Gesilda F; Silva, José R F; Moraes, Renato B; Fernandes, Thiago S; Tenorio, Bruno M; Nogueira, Romildo A

    2014-06-01

    The production, distribution and use of electricity can generate low frequency electric and magnetic fields (50-60 Hz). Considering that some studies showed adverse effects on pancreatic β-cells exposed to these fields; the present study aimed to analyze the effects of 60 Hz electric fields on membrane potential during the silent and burst phases in pancreatic β-cells using a mathematical model. Sinusoidal 60 Hz electric fields with amplitude ranging from 0.5 to 4 mV were applied on pancreatic β-cells model. The sinusoidal electric field changed burst duration, inter-burst intervals (silent phase) and spike sizes. The parameters above presented dose-dependent response with the voltage amplitude applied. In conclusion, theoretical analyses showed that a 60 Hz electric field with low amplitudes changes the membrane potential in pancreatic β-cells.

  11. Response of the electric field gradient in ion implanted BaTiO$_{3}$ to an external electric field

    CERN Document Server

    Dietrich, M; Deicher, M; Freitag, K; Samokhvalov, V; Unterricker, S

    2001-01-01

    Single crystalline, ferroelectric BaTiO$_{3}$ as material with the highest piezoelectric constants among the perovskites with ordered sublattices was implanted with $^{111}$In($^{111}$Cd). The electric field gradient at the Ti position was measured with perturbed $\\gamma-\\gamma$-angular correlation spectroscopy (PAC) while the crystal was exposed to an external electric field. A quadratic dependence could be observed: $\

  12. Tuning phase structures of a symmetrical diblock copolymer with a patterned electric field.

    Science.gov (United States)

    Kan, Di; He, Xuehao

    2016-05-11

    Electric fields can induce the orientation of the phase interfaces of block copolymers and provide a potential method to tune polymer phase structures for nanomaterial manufacture. In this work, we applied self-consistent field theory to study the self-assembly of a diblock copolymer confined between two parallel neutral substrates on which a set of electrodes was imposed to form a patterned electric field. The results showed that an alternatively distributed electric field can induce the formation of a parallel lamellar phase structure, which exists stably only in the system with selective substrates. The phase structure was proved to be sensitive to the characteristics of the electric field distribution, such as the strength of the electric field, the size and position of the electrodes, and the corresponding phase diagram was calculated in detail. The transition pathway of the phase structure from the perpendicular layered phase to the parallel layered phase was further analysed using the minimum energy path method. It is shown that the path and the active energy barrier of the phase transition depend on the electric field strength. Compound electric field patterns that can be designed to control the formation of novel and complex microphase structures were also examined. PMID:27102422

  13. Electric field driven fractal growth dynamics in polymeric medium

    Science.gov (United States)

    Dawar, Anit; Chandra, Amita

    2014-08-01

    This paper reports the extension of earlier work (Dawar and Chandra, 2012) [27] by including the influence of low values of electric field on diffusion limited aggregation (DLA) patterns in polymer electrolyte composites. Subsequently, specified cut-off value of voltage has been determined. Below the cut-off voltage, the growth becomes direction independent (i.e., random) and gives rise to ramified DLA patterns while above the cut-off, growth is governed by diffusion, convection and migration. These three terms (i.e., diffusion, convection and migration) lead to structural transition that varies from dense branched morphology (DBM) to chain-like growth to dendritic growth, i.e., from high field region (A) to constant field region (B) to low field region (C), respectively. The paper further explores the growth under different kinds of electrode geometries (circular and square electrode geometry). A qualitative explanation for fractal growth phenomena at applied voltage based on Nernst-Planck equation has been proposed.

  14. New foundations for applied electromagnetics the spatial structure of fields

    CERN Document Server

    Mikki, Said

    2016-01-01

    This comprehensive new resource focuses on applied electromagnetics and takes readers beyond the conventional theory with the use of contemporary mathematics to improve the practical use of electromagnetics in emerging areas of field communications, wireless power transfer, metamaterials, MIMO and direction-of-arrival systems. The book explores the existing and novel theories and principles of electromagnetics in order to help engineers analyze and design devices for todays applications in wireless power transfers, NFC, and metamaterials.

  15. Relaxation of Magnetic Nanoparticle Chain without Applied Field*

    Institute of Scientific and Technical Information of China (English)

    HE Liang-Ming

    2011-01-01

    The relaxation ofa one-dimensional magnetic nanoparticle linear chain with lattice constant a is investigated in absence of applied field. There is an equilibrium state (or steady state) where all magnetic moments of particles lie along the chain (x-axis), back to which the magnetic nanoparticle chain at other state will relax. It is found that the relaxation time Tx is determined by Tx = 10β × a3. This relaxation is compared with that of single magnetic nanoparticle system.

  16. Effects of an electric field on white sharks: in situ testing of an electric deterrent.

    Directory of Open Access Journals (Sweden)

    Charlie Huveneers

    Full Text Available Elasmobranchs can detect minute electromagnetic fields, <1 nV cm(-1, using their ampullae of Lorenzini. Behavioural responses to electric fields have been investigated in various species, sometimes with the aim to develop shark deterrents to improve human safety. The present study tested the effects of the Shark Shield Freedom7™ electric deterrent on (1 the behaviour of 18 white sharks (Carcharodon carcharias near a static bait, and (2 the rates of attacks on a towed seal decoy. In the first experiment, 116 trials using a static bait were performed at the Neptune Islands, South Australia. The proportion of baits taken during static bait trials was not affected by the electric field. The electric field, however, increased the time it took them to consume the bait, the number of interactions per approach, and decreased the proportion of interactions within two metres of the field source. The effect of the electric field was not uniform across all sharks. In the second experiment, 189 tows using a seal decoy were conducted near Seal Island, South Africa. No breaches and only two surface interactions were observed during the tows when the electric field was activated, compared with 16 breaches and 27 surface interactions without the electric field. The present study suggests that the behavioural response of white sharks and the level of risk reduction resulting from the electric field is contextually specific, and depends on the motivational state of sharks.

  17. Effects of an electric field on white sharks: in situ testing of an electric deterrent.

    Science.gov (United States)

    Huveneers, Charlie; Rogers, Paul J; Semmens, Jayson M; Beckmann, Crystal; Kock, Alison A; Page, Brad; Goldsworthy, Simon D

    2013-01-01

    Elasmobranchs can detect minute electromagnetic fields, electric fields have been investigated in various species, sometimes with the aim to develop shark deterrents to improve human safety. The present study tested the effects of the Shark Shield Freedom7™ electric deterrent on (1) the behaviour of 18 white sharks (Carcharodon carcharias) near a static bait, and (2) the rates of attacks on a towed seal decoy. In the first experiment, 116 trials using a static bait were performed at the Neptune Islands, South Australia. The proportion of baits taken during static bait trials was not affected by the electric field. The electric field, however, increased the time it took them to consume the bait, the number of interactions per approach, and decreased the proportion of interactions within two metres of the field source. The effect of the electric field was not uniform across all sharks. In the second experiment, 189 tows using a seal decoy were conducted near Seal Island, South Africa. No breaches and only two surface interactions were observed during the tows when the electric field was activated, compared with 16 breaches and 27 surface interactions without the electric field. The present study suggests that the behavioural response of white sharks and the level of risk reduction resulting from the electric field is contextually specific, and depends on the motivational state of sharks.

  18. Effect of an electric field on the properties of BN Möbius stripes

    Energy Technology Data Exchange (ETDEWEB)

    Lemos de Melo, J. [Departamento de Física, CCEN, Universidade Federal da Paraíba, Caixa Postal 5008, 58051-900 João Pessoa, PB (Brazil); Azevedo, S., E-mail: sazevedo@fisica.ufpb.br [Departamento de Física, CCEN, Universidade Federal da Paraíba, Caixa Postal 5008, 58051-900 João Pessoa, PB (Brazil); Kaschny, J.R. [Instituto Federal da Bahia, Campus Vitória da Conquista, Av. Amazonas 3150, 45075-265 Vitória da conquista, BA (Brazil)

    2014-09-15

    In the present work, we present a first-principles study on the effects of an external electric field on the structural stability and electronic properties of boron nitride Möbius stripes with armchair and zigzag chirality. The calculation results indicate that the gap energy can be remarkably reduced by the application of an external field. Such reduction is in principle attributed to the occurrence of Stark effect, which significance depends on the orientation of the applied field relative to the stripe axis. Moreover, the electric field produces significant changes on dipole momentum of the structure and induces a negative shift on the calculated total energy, reducing the obtained formation energy. - Highlights: • The gap energy is remarkably reduced by the application of an external field. • The electric field produces significant changes on dipole momentum. • The field induces a negative shift on the total energy due to Stark effect.

  19. Electron electric dipole moment experiment using electric-field quantized slow cesium atoms

    OpenAIRE

    Amini, Jason M.; Munger Jr., Charles T.; Gould, Harvey

    2007-01-01

    A proof-of-principle electron electric dipole moment (e-EDM) experiment using slow cesium atoms, nulled magnetic fields, and electric field quantization has been performed. With the ambient magnetic fields seen by the atoms reduced to less than 200 pT, an electric field of 6 MV/m lifts the degeneracy between states of unequal lbar mF rbar and, along with the low (approximately 3 m/s) velocity, suppresses the systematic effect from the motional magnetic field. The low velocity and small r...

  20. Electric-Field Coupling to Spin Waves in a Centrosymmetric Ferrite

    Science.gov (United States)

    Liu, Tianyu

    A systematic control of spin waves via external electric fields has been a long standing issue for the design of magnonic devices, and is of fundamental interest. One way to attain such control is to use multiferroics, whose electric and magnetic polarizations are inherently coupled. The lack of electric polarization in a centrosymmetric ferrite, however, makes direct coupling of its magnetization to external electric fields a challenge. Indirect electric control of spin waves has been accomplished by hybridizing yttrium iron garnet (YIG), a centrosymmetric ferrite, with a piezoelectric material. Here, we predict direct control of spin waves in YIG by a flexoelectric interaction, which couples an electric field to the spatial gradient of the magnetization, and thus the spin waves. Based on a superexchange model, which describes the antiferromagnetic coupling between two nearest neighbor iron ions through an oxygen ion, including spin-orbit coupling, we estimate the coupling constant and predict a phase shift linear in the applied electric fields. The theory is then confirmed by experimental measurement of the electric-field-induced phase shift in a YIG waveguide. In addition to the flexoelectric effect, another electric effect is observed, which couples the electric field directly with the magnetization of YIG. We call this a magnetoelectric effect. By adjusting the direction of the electric field, the two effects can be well separated. Experimental results agree quantitatively with the theoretical prediction. A phenomenological coupling constant for the magnetoelectric effect is also obtained. Our findings point to an important avenue for manipulating spin waves and developing electrically tunable magnonic devices.

  1. Beyond Orientation: The Impact of Electric Fields on Block Copolymers

    Energy Technology Data Exchange (ETDEWEB)

    Liedel, Clemens [RWTH Aachen University; Boker, A. [Universitat Bayreuth; Pester, Christian [RWTH Aachen University; Ruppel, Markus A [ORNL; Urban, Volker S [ORNL

    2012-01-01

    Since the first report on electric field-induced alignment of block copolymers (BCPs) in 1991, electric fields have been shown not only to direct the orientation of BCP nanostructures in bulk, solution, and thin films, but also to reversibly induce order-order transitions, affect the order-disorder transition temperature, and control morphologies' dimensions with nanometer precision. Theoretical and experimental results of the past years in this very interesting field of research are summarized and future perspectives are outlined.

  2. On the correlation analysis of electric field inside jet engine

    OpenAIRE

    KRISHNA A.; Khattab, T.; Abdelaziz, A.F.; Guizani, M.

    2014-01-01

    A Simple channel modeling method based on correlation analysis of the electric field inside jet engine is presented. The analysis of the statistical propagation characteristics of electromagnetic field inside harsh jet engine environment is presented by using `Ansys® HFSS'. In this paper, we propose a method to locate the best position for receiving probes inside jet engine with minimum correlation between the receiver points which have strong average electric field. Moreover, a MIMO system c...

  3. Numerical Simulation of Modified Radial Electric Field by LHCD

    Institute of Scientific and Technical Information of China (English)

    Wei Wei; Ding Bojiang; Kuang Guangli

    2005-01-01

    Based on the electron's radial force equilibrium, the profiles of radial electric field in OH and LHCD phase are calculated by using a simulation code. The dependences of radial electron field on electron density and its profile and different current ratio, Irf/Ip, are given. The connections between the improvement of plasma confinement and the modified radial electric field by LHCD are discussed by comparing the calculated results with the experimental results.

  4. Mechanosensory hairs in bumblebees (Bombus terrestris) detect weak electric fields

    Science.gov (United States)

    Sutton, Gregory P.; Clarke, Dominic; Morley, Erica L.; Robert, Daniel

    2016-01-01

    Bumblebees (Bombus terrestris) use information from surrounding electric fields to make foraging decisions. Electroreception in air, a nonconductive medium, is a recently discovered sensory capacity of insects, yet the sensory mechanisms remain elusive. Here, we investigate two putative electric field sensors: antennae and mechanosensory hairs. Examining their mechanical and neural response, we show that electric fields cause deflections in both antennae and hairs. Hairs respond with a greater median velocity, displacement, and angular displacement than antennae. Extracellular recordings from the antennae do not show any electrophysiological correlates to these mechanical deflections. In contrast, hair deflections in response to an electric field elicited neural activity. Mechanical deflections of both hairs and antennae increase with the electric charge carried by the bumblebee. From this evidence, we conclude that sensory hairs are a site of electroreception in the bumblebee. PMID:27247399

  5. Mechanosensory hairs in bumblebees (Bombus terrestris) detect weak electric fields.

    Science.gov (United States)

    Sutton, Gregory P; Clarke, Dominic; Morley, Erica L; Robert, Daniel

    2016-06-28

    Bumblebees (Bombus terrestris) use information from surrounding electric fields to make foraging decisions. Electroreception in air, a nonconductive medium, is a recently discovered sensory capacity of insects, yet the sensory mechanisms remain elusive. Here, we investigate two putative electric field sensors: antennae and mechanosensory hairs. Examining their mechanical and neural response, we show that electric fields cause deflections in both antennae and hairs. Hairs respond with a greater median velocity, displacement, and angular displacement than antennae. Extracellular recordings from the antennae do not show any electrophysiological correlates to these mechanical deflections. In contrast, hair deflections in response to an electric field elicited neural activity. Mechanical deflections of both hairs and antennae increase with the electric charge carried by the bumblebee. From this evidence, we conclude that sensory hairs are a site of electroreception in the bumblebee. PMID:27247399

  6. Frequency domain methods applied to forecasting electricity markets

    International Nuclear Information System (INIS)

    The changes taking place in electricity markets during the last two decades have produced an increased interest in the problem of forecasting, either load demand or prices. Many forecasting methodologies are available in the literature nowadays with mixed conclusions about which method is most convenient. This paper focuses on the modeling of electricity market time series sampled hourly in order to produce short-term (1 to 24 h ahead) forecasts. The main features of the system are that (1) models are of an Unobserved Component class that allow for signal extraction of trend, diurnal, weekly and irregular components; (2) its application is automatic, in the sense that there is no need for human intervention via any sort of identification stage; (3) the models are estimated in the frequency domain; and (4) the robustness of the method makes possible its direct use on both load demand and price time series. The approach is thoroughly tested on the PJM interconnection market and the results improve on classical ARIMA models. (author)

  7. Impact of motion along the field direction on geometric-phase-induced false electric dipole moment signals

    OpenAIRE

    Yan, H.; Plaster, B

    2011-01-01

    Geometric-phase-induced false electric dipole moment (EDM) signals, resulting from interference between magnetic field gradients and particle motion in electric fields, have been studied extensively in the literature, especially for neutron EDM experiments utilizing stored ultracold neutrons and co-magnetometer atoms. Previous studies have considered particle motion in the transverse plane perpendicular to the direction of the applied electric and magnetic fields. We show, via Monte Carlo stu...

  8. Ablation of Myocardial Tissue With Nanosecond Pulsed Electric Fields.

    Directory of Open Access Journals (Sweden)

    Fei Xie

    Full Text Available Ablation of cardiac tissue is an essential tool for the treatment of arrhythmias, particularly of atrial fibrillation, atrial flutter, and ventricular tachycardia. Current ablation technologies suffer from substantial recurrence rates, thermal side effects, and long procedure times. We demonstrate that ablation with nanosecond pulsed electric fields (nsPEFs can potentially overcome these limitations.We used optical mapping to monitor electrical activity in Langendorff-perfused New Zealand rabbit hearts (n = 12. We repeatedly inserted two shock electrodes, spaced 2-4 mm apart, into the ventricles (through the entire wall and applied nanosecond pulsed electric fields (nsPEF (5-20 kV/cm, 350 ns duration, at varying pulse numbers and frequencies to create linear lesions of 12-18 mm length. Hearts were stained either with tetrazolium chloride (TTC or propidium iodide (PI to determine the extent of ablation. Some stained lesions were sectioned to obtain the three-dimensional geometry of the ablated volume.In all animals (12/12, we were able to create nonconducting lesions with less than 2 seconds of nsPEF application per site and minimal heating (< 0.2°C of the tissue. The geometry of the ablated volume was smoother and more uniform throughout the wall than typical for RF ablation. The width of the lesions could be controlled up to 6 mm via the electrode spacing and the shock parameters.Ablation with nsPEFs is a promising alternative to radiofrequency (RF ablation of AF. It may dramatically reduce procedure times and produce more consistent lesion thickness than RF ablation.

  9. Ablation of Myocardial Tissue With Nanosecond Pulsed Electric Fields

    Science.gov (United States)

    Xie, Fei; Varghese, Frency; Pakhomov, Andrei G.; Semenov, Iurii; Xiao, Shu; Philpott, Jonathan; Zemlin, Christian

    2015-01-01

    Background Ablation of cardiac tissue is an essential tool for the treatment of arrhythmias, particularly of atrial fibrillation, atrial flutter, and ventricular tachycardia. Current ablation technologies suffer from substantial recurrence rates, thermal side effects, and long procedure times. We demonstrate that ablation with nanosecond pulsed electric fields (nsPEFs) can potentially overcome these limitations. Methods We used optical mapping to monitor electrical activity in Langendorff-perfused New Zealand rabbit hearts (n = 12). We repeatedly inserted two shock electrodes, spaced 2–4 mm apart, into the ventricles (through the entire wall) and applied nanosecond pulsed electric fields (nsPEF) (5–20 kV/cm, 350 ns duration, at varying pulse numbers and frequencies) to create linear lesions of 12–18 mm length. Hearts were stained either with tetrazolium chloride (TTC) or propidium iodide (PI) to determine the extent of ablation. Some stained lesions were sectioned to obtain the three-dimensional geometry of the ablated volume. Results In all animals (12/12), we were able to create nonconducting lesions with less than 2 seconds of nsPEF application per site and minimal heating (< 0.2°C) of the tissue. The geometry of the ablated volume was smoother and more uniform throughout the wall than typical for RF ablation. The width of the lesions could be controlled up to 6 mm via the electrode spacing and the shock parameters. Conclusions Ablation with nsPEFs is a promising alternative to radiofrequency (RF) ablation of AF. It may dramatically reduce procedure times and produce more consistent lesion thickness than RF ablation. PMID:26658139

  10. Theoretical study on coupling effects of modulation depth between two photorefractive phase gratings with an external applied field

    Institute of Scientific and Technical Information of China (English)

    YUAN Baohong; ZHOU Zhongxiang; HOU Chunfeng; SUN Xiudong

    2001-01-01

    We used the perturbation expanding method to the hopping model and studied coupling effects of the modulation depth between two photorefractive phase gratings stored in one point with an external applied DC electric field . It has been found that the modulation depth of one of the two gratings seriously affects the spatial-charge field of the other grating.

  11. Interpretation of the electric fields measured in an ionospheric critical ionization velocity experiment

    International Nuclear Information System (INIS)

    This paper deals with the quasi-dc electric fields measured in the CRIT I ionospheric release experiment, which was launched from Wallops Island on May 13, 1986. The purpose of the experiment was to study the critical ionization velocity (CIV) mechanism in the ionosphere. Two identical barium shaped charges were fired from distances of 1.99 km and 4.34 km towards a main payload, which made full three-dimensional measurements of the electric field inside the streams. There was also a subpayload separated from the main payload by a couple of kilometers along the magnetic field. The relevance of earlier proposed mechanisms for electron heating in CIV is investigated in the light of the CRIT I results. It is concluded that both the homogeneous and the ionizing front models probably apply, but in different parts of the stream. It is also possible that electrons are directly accelerated by a magnetic-field-aligned component of the electric field; the quasi-dc electric field observed within the streams had a large magnetic-field-aligned component, persisting on the time scale of the passage of the streams. The coupling between the ambient ionosphere and the ionized barium stream in CRIT I was more complicated than is usually assumed in CIV theories, with strong magnetic-field-aligned electric fields and probably current limitation as important processes. One interpretation of the quasi-dc electric field data is that the internal electric fields of the streams were not greatly modified by magnetic-field-aligned currents, i.e., a state was established where the transverse currents were to a first approximation divergence-free. It is argued that this interpretation can explain both a reversal of the strong explosion-directed electric field in burst 1 and the absence of such a reversal in burst 2

  12. Effects of Crossed Electric and Magnetic Fields on Shallow Donor Impurity Binding Energy in a Parabolic Quantum Well

    Institute of Scientific and Technical Information of China (English)

    E. Kasapoglu; H. Sari; I. S(o)kmen

    2004-01-01

    @@ We have calculated variationally the ground state binding energy of a hydrogenic donor impurity in a parabolic quantum well in the presence of crossed electric and magnetic fields. These homogeneous crossed fields are such that the magnetic field is parallel to the heterostructure layers and the electric field is applied perpendicular to the magnetic field. The dependence of the donor impurity binding energy to the well width and the strength of the electric and magnetic fields are discussed. We hope that the obtained results will provide important improvements in device applications, especially for a suitable choice of both fields in the narrow well widths.

  13. Influence of the electric field on carriers recombination zone in bilayer organic electroluminescent device

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The electroluminescence (EL) of bilayer devices (ITO/Polymer/Alq3/Al) made from two PPV derivatives (MN-PPV and MEH-PPV),respectively,and the influence of the organic layers' thickness on the characteristics of the device are investigated. Different spectra and variations are observed for different thicknesses of Alq3 layer in this bilayer organic light-emitting diodes (LEDs) as increasing applied bias. Based on the energy level and field-assisted tunneling at the interface,we attributed these phenomena to electric field redistribution in the device and field-assisted charges being transported and tunneling through energy barrier at high electric field.

  14. Effects of weak electric fields on the activity of neurons and neuronal networks

    Energy Technology Data Exchange (ETDEWEB)

    Jeffreys, J.G.R.; Deans, J.; Bikson, M.; Fox, J

    2003-07-01

    Electric fields applied to brain tissue will affect cellular properties. They will hyperpolarise the ends of cells closest to the positive part of the field, and depolarise ends closest to the negative. In the case of neurons this affects excitability. How these changes in transmembrane potential are distributed depends on the length constant of the neuron, and on its geometry; if the neuron is electrically compact, the change in transmembrane potential becomes an almost linear function of distance in the direction of the field. Neurons from the mammalian hippocampus, maintained in tissue slices in vitro, are significantly affected by fields of around 1-5 Vm{sup -1}. (author)

  15. Electric field gradients in Hg compounds

    DEFF Research Database (Denmark)

    Arcisauskaité, Vaida; Knecht, Stefan; Sauer, Stephan P. A.;

    2012-01-01

    We examine the performance of Density Functional Theory (DFT) approaches based on the Zeroth-Order Regular Approximation (ZORA) Hamiltonian (with and without inclusion of spinorbit coupling) for predictions of electric ¿eld gradients (EFGs) at the heavy atom Hg nucleus. This is achieved by compar......We examine the performance of Density Functional Theory (DFT) approaches based on the Zeroth-Order Regular Approximation (ZORA) Hamiltonian (with and without inclusion of spinorbit coupling) for predictions of electric ¿eld gradients (EFGs) at the heavy atom Hg nucleus. This is achieved...

  16. Electric field mapping inside metallized film capacitors

    DEFF Research Database (Denmark)

    Nielsen, Dennis Achton; Popok, Vladimir; Pedersen, Kjeld

    2015-01-01

    Failure mode and effect analysis (FMEA) is an important step in the reliability assessment process of electric components. It provides knowledge of the physics of failure of a component that has been subjected to a given stress profile. This knowledge enables improvement of the component robustness...... of the metallization stripes had lost contact to the end-spray. Thus, it is shown that the surface electric potential distributions on micro-sectioned film capacitors can be obtained through KPFM analysis. We have, from KPFM measurements, shown that the degraded capacitors under investigation had suffered from...

  17. Novel high power impulse magnetron sputtering enhanced by an auxiliary electrical field

    Science.gov (United States)

    Li, Chunwei; Tian, Xiubo

    2016-08-01

    The high power impulse magnetron sputtering (HIPIMS) technique is a novel highly ionized physical vapor deposition method with a high application potential. However, the electron utilization efficiency during sputtering is rather low and the metal particle ionization rate needs to be considerably improved to allow for a large-scale industrial application. Therefore, we enhanced the HIPIMS technique by simultaneously applying an electric field (EF-HIPIMS). The effect of the electric field on the discharge process was studied using a current sensor and an optical emission spectrometer. Furthermore, the spatial distribution of the electric potential and electric field during the EF-HIPIMS process was simulated using the ANSYS software. The results indicate that a higher electron utilization efficiency and a higher particle ionization rate could be achieved. The auxiliary anode obviously changed the distribution of the electric potential and the electric field in the discharge region, which increased the plasma density and enhanced the degree of ionization of the vanadium and argon gas. Vanadium films were deposited to further compare both techniques, and the morphology of the prepared films was investigated by scanning electron microscopy. The films showed a smaller crystal grain size and a denser growth structure when the electric field was applied during the discharge process.

  18. Novel high power impulse magnetron sputtering enhanced by an auxiliary electrical field.

    Science.gov (United States)

    Li, Chunwei; Tian, Xiubo

    2016-08-01

    The high power impulse magnetron sputtering (HIPIMS) technique is a novel highly ionized physical vapor deposition method with a high application potential. However, the electron utilization efficiency during sputtering is rather low and the metal particle ionization rate needs to be considerably improved to allow for a large-scale industrial application. Therefore, we enhanced the HIPIMS technique by simultaneously applying an electric field (EF-HIPIMS). The effect of the electric field on the discharge process was studied using a current sensor and an optical emission spectrometer. Furthermore, the spatial distribution of the electric potential and electric field during the EF-HIPIMS process was simulated using the ANSYS software. The results indicate that a higher electron utilization efficiency and a higher particle ionization rate could be achieved. The auxiliary anode obviously changed the distribution of the electric potential and the electric field in the discharge region, which increased the plasma density and enhanced the degree of ionization of the vanadium and argon gas. Vanadium films were deposited to further compare both techniques, and the morphology of the prepared films was investigated by scanning electron microscopy. The films showed a smaller crystal grain size and a denser growth structure when the electric field was applied during the discharge process.

  19. Novel high power impulse magnetron sputtering enhanced by an auxiliary electrical field.

    Science.gov (United States)

    Li, Chunwei; Tian, Xiubo

    2016-08-01

    The high power impulse magnetron sputtering (HIPIMS) technique is a novel highly ionized physical vapor deposition method with a high application potential. However, the electron utilization efficiency during sputtering is rather low and the metal particle ionization rate needs to be considerably improved to allow for a large-scale industrial application. Therefore, we enhanced the HIPIMS technique by simultaneously applying an electric field (EF-HIPIMS). The effect of the electric field on the discharge process was studied using a current sensor and an optical emission spectrometer. Furthermore, the spatial distribution of the electric potential and electric field during the EF-HIPIMS process was simulated using the ANSYS software. The results indicate that a higher electron utilization efficiency and a higher particle ionization rate could be achieved. The auxiliary anode obviously changed the distribution of the electric potential and the electric field in the discharge region, which increased the plasma density and enhanced the degree of ionization of the vanadium and argon gas. Vanadium films were deposited to further compare both techniques, and the morphology of the prepared films was investigated by scanning electron microscopy. The films showed a smaller crystal grain size and a denser growth structure when the electric field was applied during the discharge process. PMID:27587123

  20. Electric-field-assisted crystallisation in phase-change materials

    Energy Technology Data Exchange (ETDEWEB)

    Kohary, Krisztian; Diosdado, Jorge A.V.; Ashwin, Peter; Wright, C. David [College of Engineering, Mathematics, and Physical Sciences, University of Exeter (United Kingdom)

    2012-10-15

    Phase-change materials are of intense research interest due mainly to their use in phase-change memory (PCM) devices that are emerging as a promising technology for future non-volatile, solid-state, electrical storage. Electrically driven transitions from the amorphous to the crystalline phase in such devices exhibit characteristic threshold switching. Several alternative electronic explanations for the origins of this characteristic behaviour have been put forward, for example Poole-Frenkel effects, delocalisation of tail states, field emission processes and space charge limited currents [for a full discussion, see Radielli et al., J. Appl. Phys. 103, 111101 (2008) and Simon et al., MRS Proc. 1251, H01-H011 (2010)]. However, an alternative to these conventional electronic models of threshold switching is based on electric field induced lowering of the system free energy, leading to the field induced nucleation of conducting crystal filaments. In this paper we investigate this alternative view. We present a detailed kinetics study of crystallisation in the presence of an electric field for the phase-change material Ge{sub 2}Sb{sub 2}Te{sub 5}. We derive quantitative crystallisation maps to show the effects of both temperature and electric field on crystallisation and we identify field ranges and parameter values where the electric field might play a significant role. Then we carry out physically realistic simulations of the threshold switching process in typical phase-change device structures, both with and without electric field dependent energy contributions to the system free energy. Our results show that threshold switching can be obtained by a mechanism driven purely by electric field induced nucleation, but the fields so required are large, of the order of 300 MV m{sup -1}, and significantly larger than the experimentally measured threshold fields. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. Field and temperature dependence of the small polaron hopping electrical conductivity in 1D disordered systems

    Energy Technology Data Exchange (ETDEWEB)

    Triberis, G P; Dimakogianni, M, E-mail: gtriber@phys.uoa.g [Solid State Section, Physics Department, University of Athens, Panepistimiopolis, 15784 Zografos, Athens (Greece)

    2009-09-23

    We investigate the effect of the electric field and the temperature on the electrical conductivity of one-dimensional disordered systems due to phonon assisted hopping of small polarons. The microscopic transport mechanism is treated within the framework of the generalized molecular crystal model and the Kubo formula, while percolation theoretical arguments lead to analytical expressions for the macroscopic behavior of the electrical conductivity at high (multi-phonon assisted hopping) and low (few-phonon assisted hopping) temperatures under the influence of moderate electric fields. The theoretical results are successfully applied to recent experimental findings for a wide temperature range and from low up to moderate electric fields. Comparison is made with other theories.

  2. Energetic Macroscopic Representation Applied To An Electrical Urban Transport System

    Directory of Open Access Journals (Sweden)

    Claudia POPESCU

    2002-12-01

    Full Text Available An energetic description of the electric transport urban system ASTRAIK 415T is proposed according to a specific formalism. This is used to simulate the trolleybus system, equipped with a chopper and a direct current series motor. DC series motor is still used for trolleybus and metro, driven by a GTO or IGBT chopper µC-controlled, which allows the implementation of command algorithms. From this synthetically representation a complete model of the electromechanical system was implemented using the Matlab-Simulink simulation environment. A control structure was deduced through model inversion. This will allow the study of the transient phenomena and the implementation of different command laws taking into account the minimum energy losses

  3. Scattering and pair creation by L-constant electric field

    CERN Document Server

    Gavrilov, S P

    2015-01-01

    Using QFT approach developed by us in Ref. arXiv:1506.01156, we consider particle scattering and vacuum instability in the so-called L-constant electric field, which is a constant electric field confined between two capacitor plates separated by a finite distance L. We obtain and analyze special sets of stationary solutions of the Dirac and Klein-Gordon equations with the L-constant electric field. Then, we represent probabilities of particle scattering and characteristics of the vacuum instability (related to the pair creation) in terms of the introduced solutions. From exact formulas, we derive asymptotic expressions for the differential mean numbers, for the total mean number of created particles, and for the vacuum-to-vacuum transition probability. Using the equivalence principle, we demonstrate that the distributions of created particles by L-constant electric field and gravitational field of a black hole have similar thermal structure.

  4. Electron propagation in crossed magnetic and electric fields

    CERN Document Server

    Kramer, T; Kleber, M; Kramer, Tobias; Bracher, Christian; Kleber, Manfred

    2004-01-01

    Laser-atom interaction can be an efficient mechanism for the production of coherent electrons. We analyze the dynamics of monoenergetic electrons in the presence of uniform, perpendicular magnetic and electric fields. The Green function technique is used to derive analytic results for the field--induced quantum mechanical drift motion of i) single electrons and ii) a dilute Fermi gas of electrons. The method yields the drift current and, at the same time it allows us to quantitatively establish the broadening of the (magnetic) Landau levels due to the electric field: Level number k is split into k+1 sublevels that render the $k$th oscillator eigenstate in energy space. Adjacent Landau levels will overlap if the electric field exceeds a critical strength. Our observations are relevant for quantum Hall configurations whenever electric field effects should be taken into account.

  5. Visualization of electrical field of electrode using voltage-controlled fluorescence release.

    Science.gov (United States)

    Jia, Wenyan; Wu, Jiamin; Gao, Di; Wang, Hao; Sun, Mingui

    2016-08-01

    In this study we propose an approach to directly visualize electrical current distribution at the electrode-electrolyte interface of a biopotential electrode. High-speed fluorescent microscopic images are acquired when an electric potential is applied across the interface to trigger the release of fluorescent material from the surface of the electrode. These images are analyzed computationally to obtain the distribution of the electric field from the fluorescent intensity of each pixel. Our approach allows direct observation of microscopic electrical current distribution around the electrode. Experiments are conducted to validate the feasibility of the fluorescent imaging method. PMID:27253615

  6. High Dynamic Range Electric Field Sensor for Electromagnetic Pulse Detection

    CERN Document Server

    Lin, Che-Yun; Lee, Beom Suk; Zhang, Xingyu; Chen, Ray T

    2014-01-01

    We design a high dynamic range electric field sensor based on domain inverted electro-optic (E-O) polymer Y-fed directional coupler for electromagnetic wave detection. This electrode-less, all optical, wideband electrical field sensor is fabricated using standard processing for E-O polymer photonic devices. Experimental results demonstrate effective detection of electric field from 16.7V/m to 750KV/m at a frequency of 1GHz, and spurious free measurement range of 70dB.

  7. Giant and tunable electric field enhancement in the terahertz regime.

    Science.gov (United States)

    Lu, Xiaoyuan; Wan, Rengang; Wang, Guoxi; Zhang, Tongyi; Zhang, Wenfu

    2014-11-01

    A novel array of slits design combining the nano-slit grating and dielectric-metal is proposed to obtain giant and tunable electric field enhancement in the terahertz regime. The maximum amplitude of electric field is more than 6000 times larger than that of the incident electric field. It is found that the enhancement depends primarily on the stripe and nano-slits width of grating, as well as the thickness of spacer layer. This property is particularly beneficial for the realization of ultra-sensitive nanoparticles detection and nonlinear optics in the terahertz range, such as the second harmonic generation (SHG).

  8. Effects of Orthogonal Rotating Electric Fields on Electrospinning Process

    CERN Document Server

    Cipolletta, Federico; Pontrelli, Giuseppe; Pisignano, Dario; Succi, Sauro

    2016-01-01

    Electrospinning is an nanotechnology process whereby an external electric field is used to accelerate and stretch a charged polymer jet, so as to produce fibers at nanoscale diameters. In quest of a further reduction in the cross section of electrified jets hence of the resulting electrospun fibers, we explore the effects of an external rotating electric field orthogonal to the jet direction. Through extensive particle simulations, it is shown that by a proper tuning of the electric field amplitude and frequency, a reduction of up to a 30% in the aforementioned radius can be obtained, thereby opening new perspectives in the design of future ultra-thin electrospun fibres.

  9. Effects of Electric Fields on the Combustion Characteristics of Lean Burn Methane-Air Mixtures

    Directory of Open Access Journals (Sweden)

    Jianfeng Fang

    2015-03-01

    Full Text Available In this work, the effects of the electric fields on the flame propagation and combustion characteristics of lean premixed methane–air mixtures were experimentally investigated in a constant volume chamber. Results show that the flame front is remarkably stretched by the applied electric field, the stretched flame propagation velocity and the average flame propagation velocity are all accelerated significantly as the input voltage increases. This indicates that the applied electric field can augment the stretch in flame, and the result is more obvious for leaner mixture. According to the analyses of the combustion pressure variation and the heat release rate, the peak combustion pressure Pmax increases and its appearance time tp is advanced with the increase of the input voltage. For the mixture of λ = 1.6 at the input voltage of −12 kV, Pmax increases by almost 12.3%, and tp is advanced by almost 31.4%, compared to the case of without electric fields. In addition, the normalized mass burning rate and the accumulated mass fraction burned are all enhanced substantially, and the flame development duration and the rapid burning duration are remarkably reduced with the increase of the input voltage, and again, the influence of electric field is more profound for leaner mixtures. The results can be explained by the electric field-induced stretch effects on lean burn methane-air mixture.

  10. Electrical properties and electrical field in depletion layer for CZT crystals

    Institute of Scientific and Technical Information of China (English)

    LI Qiang; JIE Wan-qi; FU Li; YANG Ge; ZHA Gang-qiang; WANG Tao; BAI Xu-xu

    2006-01-01

    Current—voltage (I—V) and capacitance-voltage (C—V) characteristics of Au/p-CZT contacts with different surface treatments on cadmium zinc telluride (CZT) wafer's surface were measured with Agilent 4339B high resistance meter and Agilent 4294A precision impedance analyzer,respectively. The Schottky barrier height was 0.85±0.05,0.96±0.05 eV for non-passivated and passivated CZT crystals by I—V measurement. By C—V measurement,the Schottky barrier height was 1.39±0.05,1.51±0.05 eV for non-passivated and passivated CZT crystals. The results show that the passivation treatment can increase the barrier height of the Au/p-CZT contact and decrease the leakage current. The main reason is that the higher barrier height of Au/p-CZT contacts can decrease the possibility for electrons to pass through the native TeO2 film. Most of the applied voltage appears on the depleted layer and there is only a negligible voltage drops across the nearly undepleted region. Furthermore,the electric field in the depleted layer is not uniform and can be calculated by the depletion approximation. The maximum electric field of CZT crystals is Em1=133 V/cm at x=0 for non-passivated CZT crystal and Em2=55 V/cm for passivated CZT crystal,respectively.

  11. Shutdown risk management applied at Philadelphia Electric Company

    International Nuclear Information System (INIS)

    The development and implementation of an effective risk management program requires basic risk or safety knowledge and the conversion of such information into effective management tools. ERIN Engineering and Research, Inc., under contract to the Electric Power Research Institute, has developed an effective program. Outage Risk Assessment and Management (ORAM), to provide plant and management personnel with understandable results of shutdown risk studies. With this tool, the impact of plans and decision options can be readily determined and displayed for the decision maker. This paper describes these methods and their application to the Limerick Nuclear Station of Philadelphia Electric Company. It also sets forth a broader application of these methods to include support of management decisions at-power and following forced outages. The result is an integrated risk management framework which can allow management and technical personnel to utilize readily available and understandable risk insights to optimize each activity. This paper addresses the resolution of several key issues in detail: How was the ORAM risk management method employed to represent the existing plant shutdown procedures and policies? How did the ORAM risk management method enhance the decision-making ability of the outage management staff? How was the ORAM software efficiently integrated with the outage scheduling software? How is quantitative risk information generated and used for outage planning and control? The ORAM risk management philosophy utilizes a series of colors to depict various risk configurations. Each such configuration has associated with it clear guidance. By modifying the conditions existing in the plant it is possible to impact the type of risk being encountered as well as the guidance which is appropriate for that period. In addition, the duration of a particular configuration can be effectively managed to reduce the overall risk impact. These are achieved with minimal

  12. Electrodynamics—molecular dynamics simulations of the stability of Cu nanotips under high electric field

    Science.gov (United States)

    Veske, Mihkel; Parviainen, Stefan; Zadin, Vahur; Aabloo, Alvo; Djurabekova, Flyura

    2016-06-01

    The shape memory effect and pseudoelasticity in Cu nanowires represent a possible pair of mechanisms that prevents high aspect ratio nanosized field electron emitters from being stable at room temperature and permits their growth under high electric field. By utilizing hybrid electrodynamics–molecular dynamics simulations, we show that a global electric field of 1 GV m‑1 or more significantly increases the stability and critical temperature of spontaneous reorientation of nanosized    Cu field emitters. We also show that in the studied tips the stabilizing effect of an external applied electric field is an order of magnitude greater than the destabilization caused by the field emission current. We detect the critical temperature of spontaneous reorientation using a tool that spots changes in crystal structure. The method is compatible with techniques that consider the change in potential energy, has a wider range of applicability and allows different stages in the reorientation processes to be pinpointed.

  13. Applying Nitrogen Site-Specifically Using Soil Electrical Conductivity Maps and Precision Agriculture Technology

    Directory of Open Access Journals (Sweden)

    E.D. Lund

    2001-01-01

    Full Text Available Soil texture varies significantly within many agricultural fields. The physical properties of soil, such as soil texture, have a direct effect on water holding capacity, cation exchange capacity, crop yield, production capability, and nitrogen (N loss variations within a field. In short, mobile nutrients are used, lost, and stored differently as soil textures vary. A uniform application of N to varying soils results in a wide range of N availability to the crop. N applied in excess of crop usage results in a waste of the grower’s input expense, a potential negative effect on the environment, and in some crops a reduction of crop quality, yield, and harvestability. Inadequate N levels represent a lost opportunity for crop yield and profit. The global positioning system (GPS-referenced mapping of bulk soil electrical conductivity (EC has been shown to serve as an effective proxy for soil texture and other soil properties. Soils with a high clay content conduct more electricity than coarser textured soils, which results in higher EC values. This paper will describe the EC mapping process and provide case studies of site-specific N applications based on EC maps. Results of these case studies suggest that N can be managed site-specifically using a variety of management practices, including soil sampling, variable yield goals, and cropping history.

  14. Low-energy electronic states of carbon nanocones in an electric field

    Institute of Scientific and Technical Information of China (English)

    Jun-Liang Chen; Ming-Horng Su; Chi-Chuan Hwang; Jian-Ming Lu; Chia-Chang Tsai

    2010-01-01

    The low-energy electronic states and energy gaps of carbon nanocones in an electric field are studied using a single-p-band tight-binding model. The analysis considers five perfect carbon nanocones with disclination angles of 60°, 120°, 180°, 240°and 300°, respectively. The numerical results reveal that the low-energy electronic states and energy gaps of a carbon nanocones are highly sensitive to its geometric shape (i.e. the disclination angle and height), and to the direction and magnitude of an electric field. The electric field causes a strong modulation of the state energies and energy gaps of the nanocones, changes their Fermi levels, and induces zero-gap transitions. The energy-gap modulation effect becomes particularly pronounced at higher strength of the applied electric field, and is strongly related to the geometric structure of the nanocone.

  15. Electric Field-Controlled Crystallizing CaCO3 Nanostructures from Solution.

    Science.gov (United States)

    Qi, Jian Quan; Guo, Rui; Wang, Yu; Liu, Xuan Wen; Chan, Helen Lai Wah

    2016-12-01

    The role of electric field is investigated in determining the structure, morphology, and crystallographic characteristics of CaCO3 nanostructures crystallized from solution. It is found that the lattice structure and crystalline morphology of CaCO3 can be tailed by the electric field applied to the solution during its crystallization. The calcite structure with cubic-like morphology can be obtained generally without electric field, and the vaterite structure with the morphology of nanorod is formed under the high electric field. The vaterite nanorods can be piled up to the petaliform layers. Both the nanorod and the petaliform layer can have mesocrystal structures which are piled up by much fine units of the rods with the size of several nanometers. Beautiful rose-like nanoflowers can be self-arranged by the petaliform layers. These structures can have potential application as carrier for medicine to involve into metabolism of living cell. PMID:26932759

  16. Electric-field-modulated nonvolatile resistance switching in VO₂/PMN-PT(111) heterostructures.

    Science.gov (United States)

    Zhi, Bowen; Gao, Guanyin; Xu, Haoran; Chen, Feng; Tan, Xuelian; Chen, Pingfan; Wang, Lingfei; Wu, Wenbin

    2014-04-01

    The electric-field-modulated resistance switching in VO2 thin films grown on piezoelectric (111)-0.68Pb(Mg1/3Nb2/3)O3-0.32PbTiO3 (PMN-PT) substrates has been investigated. Large relative change in resistance (10.7%) was observed in VO2/PMN-PT(111) hererostructures at room temperature. For a substrate with a given polarization direction, stable resistive states of VO2 films can be realized even when the applied electric fields are removed from the heterostructures. By sweeping electric fields across the heterostructure appropriately, multiple resistive states can be achieved. These stable resistive states result from the different stable remnant strain states of substrate, which is related to the rearrangements of ferroelectric domain structures in PMN-PT(111) substrate. The resistance switching tuned by electric field in our work may have potential applications for novel electronic devices. PMID:24634978

  17. Electric Field-Controlled Crystallizing CaCO3 Nanostructures from Solution.

    Science.gov (United States)

    Qi, Jian Quan; Guo, Rui; Wang, Yu; Liu, Xuan Wen; Chan, Helen Lai Wah

    2016-12-01

    The role of electric field is investigated in determining the structure, morphology, and crystallographic characteristics of CaCO3 nanostructures crystallized from solution. It is found that the lattice structure and crystalline morphology of CaCO3 can be tailed by the electric field applied to the solution during its crystallization. The calcite structure with cubic-like morphology can be obtained generally without electric field, and the vaterite structure with the morphology of nanorod is formed under the high electric field. The vaterite nanorods can be piled up to the petaliform layers. Both the nanorod and the petaliform layer can have mesocrystal structures which are piled up by much fine units of the rods with the size of several nanometers. Beautiful rose-like nanoflowers can be self-arranged by the petaliform layers. These structures can have potential application as carrier for medicine to involve into metabolism of living cell.

  18. Applying electrical utility least-cost approach to transportation planning

    Energy Technology Data Exchange (ETDEWEB)

    McCoy, G.A.; Growdon, K.; Lagerberg, B.

    1994-09-01

    Members of the energy and environmental communities believe that parallels exist between electrical utility least-cost planning and transportation planning. In particular, the Washington State Energy Strategy Committee believes that an integrated and comprehensive transportation planning process should be developed to fairly evaluate the costs of both demand-side and supply-side transportation options, establish competition between different travel modes, and select the mix of options designed to meet system goals at the lowest cost to society. Comparisons between travel modes are also required under the Intermodal Surface Transportation Efficiency Act (ISTEA). ISTEA calls for the development of procedures to compare demand management against infrastructure investment solutions and requires the consideration of efficiency, socioeconomic and environmental factors in the evaluation process. Several of the techniques and approaches used in energy least-cost planning and utility peak demand management can be incorporated into a least-cost transportation planning methodology. The concepts of avoided plants, expressing avoidable costs in levelized nominal dollars to compare projects with different on-line dates and service lives, the supply curve, and the resource stack can be directly adapted from the energy sector.

  19. Molecular dynamics simulation study on behaviors of liquid 1,2-dichioroethane under external electric fields

    Institute of Scientific and Technical Information of China (English)

    杜志强; 陈正隆

    2003-01-01

    Molecular dynamics simulation was carried out to study the behavior of liquid 1,2-dichloroethane molecules under external electric fields including direct current field, alternating current field and positive-half-period cosin field. The maximum applied field strength was 108 V/m , the maximum frequency of the alternating current field and that of the positive-half-period cosine field was 1012 Hz . The simulation revealed that the field type and field strength act on the population of the molecular configuration. In the strong direct current field, all trans forms converted completely into gauche forms. Order parameter and the correlation of the system torsion angle were also investigated. The results suggested that these two dynamical parameters depended also on the field type and the field strength. The maximum of order parameter was found to be at 0.6in the strong direct current field.

  20. Molecular dynamics simulation study on behaviors of liquid 1,2-dichloroethane under external electric fields

    Institute of Scientific and Technical Information of China (English)

    杜志强; 陈正隆

    2003-01-01

    Molecular dynamics simulation was carried out to study the behavior of liquid 1,2-dichloroethane molecules under external electric fields including direct current field, alternating current field and positive-half-period cosin field. The maximum applied field strength was 108 V/m , the maximum frequency of the alternating current field and that of the positive-half-period cosine field was 1012 Hz .The simulation revealed that the field type and field strength act on the population of the molecular configuration. In the strong direct current field, all trans forms converted completely into gauche forms. Order parameter and the correlation of the system torsion angle were also investigated. The results suggested that these two dynamical parameters depended also on the field type and the field strength. The maximum of order parameter was found to be at 0.6 in the strong direct current field.

  1. Exposure assessment of extremely low frequency electric fields in Tehran, Iran, 2010.

    Science.gov (United States)

    Nassiri, Parvin; Esmaeilpour, Mohammad Reza Monazzam; Gharachahi, Ehsan; Haghighat, Gholamali; Yunesian, Masoud; Zaredar, Narges

    2013-01-01

    Extremely Low-Frequency (ELF) electric and magnetic fields belonging to the nonionizing electromagnetic radiation spectrum have a frequency of 50 - 60 Hz. All people are exposed to a complex set of electric and magnetic fields that spread throughout the environment. The current study was carried out to assess people's exposure to an ELF electric field in the Tehran metropolitan area in 2010. The measurement of the electronic fields was performed using an HI-3604 power frequency field strength measurement device. A total number of 2,753 measurements were performed. Afterward, the data obtained were transferred to the base map using Arc View Version 3.2 and Arc Map Version 9.3. Finally, an interpolation method was applied to expand the intensity of the electric field to the entire city. Based on the results obtained, the electric field was divided into three parts with various intensities including 0-5 V m, 5-15 V m, and >15 V m. It should be noted that the status of high voltage transmission lines, electric substations, and specific points including schools and hospitals were also marked on the map. Minimum and maximum electric field intensities were measured tantamount to 0.31 V m and 19.80 V m, respectively. In all measurements, the electric field was much less than the amount provided in the ICNIRP Guide. The results revealed that 141 hospitals and 6,905 schools are situated in an area with electric field intensity equal to 0-5 V m, while 15 hospitals and 95 schools are located in zones of 5-15 V m and more than 15 V m. Examining high voltage transmission lines and electric substations in Tehran and its suburbs suggested that the impact of the lines on the background electric field of the city was low. Accordingly, 0.97 km of Tehran located on the city border adjacent to the high voltage transmission lines have an electric field in the range of 5 to 15 V m. The noted range is much lower than the available standards. In summary, it can be concluded that the public

  2. Desalination of a brick by application of an electric DC field

    DEFF Research Database (Denmark)

    Ottosen, Lisbeth M.; Rörig-Dalgaard, Inge

    2009-01-01

    Salts in masonry can cause various problems as decay of the masonry itself, lost adhesion of plaster and hygroscopic moisture. Chlorides are among the most common building salts and the present paper is focused on removal of chlorides from a brick in an applied electric field as a step towards...... to the brick during submersion and slower removed in the applied electric field than KCl. This indicates that the removal rate of chloride depends on the associated cation and this must be taken into account when desiding the duration of full scale actions. The electrochemical desalination was very efficient...

  3. Electric field mapping inside metallized film capacitors

    OpenAIRE

    Nielsen, Dennis Achton; Popok, Vladimir; Pedersen, Kjeld

    2015-01-01

    Failure mode and effect analysis (FMEA) is an important step in the reliability assessment process of electric components. It provides knowledge of the physics of failure of a component that has been subjected to a given stress profile. This knowledge enables improvement of the component robustness and durability and serves as verification that failure- and degradation mechanisms remain the same at different stress levels during accelerated testing. In this work we have used Kelvin probe forc...

  4. The bee, the flower and the electric field

    Directory of Open Access Journals (Sweden)

    Robert Daniel

    2016-01-01

    Full Text Available Insects use several different senses to forage on flowers, and detect floral cues such as color, shape, pattern, humidity and chemical volatiles. This presentation will present our discovery of a previously unappreciated sensory capacity in bumblebees (Bombus terrestris: the detection of floral electric fields. We show that these floral fields act as informational cues, and that they can be affected by the visit of naturally electrically charged bees. Like visual cues, floral electric fields exhibit variations in pattern and structure, which can be discriminated by bumblebees. We also show that such electric field information contributes to the complex array of floral cues that together improve a pollinator’s memory of floral rewards. Floral electric fields arise from complex interactions with the surrounding atmosphere, an interaction between plants and their environment that not well understood. Because floral electric fields can change within seconds, this new sensory modality - electrostatic field detection- may facilitate rapid and dynamic communication between flowers and their pollinators.

  5. Analysis on Electric Field Around HVAC-HVDC Hybrid Transmission Lines%Analysis on Electric Field Around HVAC-HVDC Hybrid Transmission Lines

    Institute of Scientific and Technical Information of China (English)

    LI Qian; LIU Jun-xiang; LI Hua; LIN Fu-chang

    2011-01-01

    As the transmission line corridors become more and more rare in China, it is now inevitable for people to construct HVAC-HVDC hybrid transmission lines. The research on the electric field around the transmission lines plays an important role in evaluating the electromagnetic environment nearby. However, few existing research now considered the mutual effect of HVAC-HVDC hybrid transmission lines. Thus, this research designed a program based on windows, which calculated the surface voltage gradient on the transmission lines and the electric field at ground level respectively. This research calculated the surface voltage gradient on the transmission lines by applying the improved method of successive images. For the electric field at ground level under AC transmission line, simula- tion charge method is used, while for the electric field at the ground level under DC transmission lines, deutsch as- sumption method is used. Comparing the results generated by the calculation with those in published literature, the program is reliable. Taking 500 kV transmission lines as an example, when considering the mutual effect of the HVAC-HVDC'lines, the amplitude of the surface voltage gradient will increase by about 10% and the amplitude of the electric field at ground level will increase by about 8%, making the mutual effect of the AC and DC lines unneglectable. Larger part of the electric field at ground level under hybrid lines is produced by the DC line. Thus, in order to control the electric field at ground level under hybrid lines, it should pay more attention on that produced by the DC line.

  6. Mechanical noise limit of a strain coupled magneto(elasto)electric sensor operating under a magnetic or an electric field modulation

    OpenAIRE

    X. Zhuang; Sing, M. Lam Chok; Lam Chok Sing, Marc; Dolabdjian, C.; Wang, Y.(Institute of High Energy Physics, Beijing, 100049, China); P. Finkel; Li, J; Viehland, D.

    2014-01-01

    International audience; The mechanical noise limit of a strain coupled Magneto(elasto)Electric (ME) composite has been investigated when a magnetic or an electric field modulation is applied to sense a low frequency magnetic field and access DC field measurement capabilities. The sensitivity and noise of such a composite sensor was derived from constitutive equations based on the piezoelectric and ferromagnetic material properties. The analysis was used to evaluate the equivalent noise floor ...

  7. Lorentz force electrical impedance tomography using magnetic field measurements

    Science.gov (United States)

    Zengin, Reyhan; Güneri Gençer, Nevzat

    2016-08-01

    In this study, magnetic field measurement technique is investigated to image the electrical conductivity properties of biological tissues using Lorentz forces. This technique is based on electrical current induction using ultrasound together with an applied static magnetic field. The magnetic field intensity generated due to induced currents is measured using two coil configurations, namely, a rectangular loop coil and a novel xy coil pair. A time-varying voltage is picked-up and recorded while the acoustic wave propagates along its path. The forward problem of this imaging modality is defined as calculation of the pick-up voltages due to a given acoustic excitation and known body properties. Firstly, the feasibility of the proposed technique is investigated analytically. The basic field equations governing the behaviour of time-varying electromagnetic fields are presented. Secondly, the general formulation of the partial differential equations for the scalar and magnetic vector potentials are derived. To investigate the feasibility of this technique, numerical studies are conducted using a finite element method based software. To sense the pick-up voltages a novel coil configuration (xy coil pairs) is proposed. Two-dimensional numerical geometry with a 16-element linear phased array (LPA) ultrasonic transducer (1 MHz) and a conductive body (breast fat) with five tumorous tissues is modeled. The static magnetic field is assumed to be 4 Tesla. To understand the performance of the imaging system, the sensitivity matrix is analyzed. The sensitivity matrix is obtained for two different locations of LPA transducer with eleven steering angles from -{{25}\\circ} to {{25}\\circ} at intervals of {{5}\\circ} . The characteristics of the imaging system are shown with the singular value decomposition (SVD) of the sensitivity matrix. The images are reconstructed with the truncated SVD algorithm. The signal-to-noise ratio in measurements is assumed 80 dB. Simulation studies

  8. Lorentz force electrical impedance tomography using magnetic field measurements.

    Science.gov (United States)

    Zengin, Reyhan; Gençer, Nevzat Güneri

    2016-08-21

    In this study, magnetic field measurement technique is investigated to image the electrical conductivity properties of biological tissues using Lorentz forces. This technique is based on electrical current induction using ultrasound together with an applied static magnetic field. The magnetic field intensity generated due to induced currents is measured using two coil configurations, namely, a rectangular loop coil and a novel xy coil pair. A time-varying voltage is picked-up and recorded while the acoustic wave propagates along its path. The forward problem of this imaging modality is defined as calculation of the pick-up voltages due to a given acoustic excitation and known body properties. Firstly, the feasibility of the proposed technique is investigated analytically. The basic field equations governing the behaviour of time-varying electromagnetic fields are presented. Secondly, the general formulation of the partial differential equations for the scalar and magnetic vector potentials are derived. To investigate the feasibility of this technique, numerical studies are conducted using a finite element method based software. To sense the pick-up voltages a novel coil configuration (xy coil pairs) is proposed. Two-dimensional numerical geometry with a 16-element linear phased array (LPA) ultrasonic transducer (1 MHz) and a conductive body (breast fat) with five tumorous tissues is modeled. The static magnetic field is assumed to be 4 Tesla. To understand the performance of the imaging system, the sensitivity matrix is analyzed. The sensitivity matrix is obtained for two different locations of LPA transducer with eleven steering angles from [Formula: see text] to [Formula: see text] at intervals of [Formula: see text]. The characteristics of the imaging system are shown with the singular value decomposition (SVD) of the sensitivity matrix. The images are reconstructed with the truncated SVD algorithm. The signal-to-noise ratio in measurements is assumed 80 d

  9. The Magnetic Fields of Electric Motors and their EMC

    OpenAIRE

    Dobroslav Kovac; Irena Kovacova

    2008-01-01

    This paper deals with the computer analysis of the electromagnetic compatibility (EMC) problems focused on the area of electrical machines, which can also disclose the concerning startling facts. A problem of interference between electric motor and surrounding space caused by the electromagnetic field radiation is discussed too.

  10. Electric and magnetic field measurements. Annual report 80

    Energy Technology Data Exchange (ETDEWEB)

    McKnight, R.H.; Kotter, F.R.; Misakian, M.; Ortiz, P.

    1981-02-01

    The NBS program is concerned with developing methods for evaluating and calibrating instrumentation for use in measuring the electric field and various ion-related electrical quantities in the vicinity of high-voltage direct current (HVDC) transmission lines and in apparatus designed to simulate the transmission line environment.

  11. Monte Carlo simulations of air showers in atmospheric electric fields

    CERN Document Server

    Buitink, S; Falcke, H; Heck, D; Kuijpers, J

    2009-01-01

    The development of cosmic ray air showers can be influenced by atmospheric electric fields. Under fair weather conditions these fields are small, but the strong fields inside thunderstorms can have a significant effect on the electromagnetic component of a shower. Understanding this effect is particularly important for radio detection of air showers, since the radio emission is produced by the shower electrons and positrons. We perform Monte Carlo simulations to calculate the effects of different electric field configurations on the shower development. We find that the electric field becomes important for values of the order of 1 kV/cm. Not only can the energy distribution of electrons and positrons change significantly for such field strengths, it is also possible that runaway electron breakdown occurs at high altitudes, which is an important effect in lightning initiation.

  12. Effective critical electric field for runaway electron generation

    CERN Document Server

    Stahl, Adam; Decker, Joan; Embréus, Ola; Fülöp, Tünde

    2014-01-01

    In this letter we investigate factors that influence the effective critical electric field for runaway electron generation in plasmas. We present numerical solutions of the kinetic equation, and discuss the implications for the threshold electric field. We show that the effective electric field necessary for significant runaway formation often is higher than previously calculated due to both (1) extremely strong dependence of primary generation on temperature, and (2) synchrotron radiation losses. We also address the effective critical field in the context of a transition from runaway growth to decay. We find agreement with recent experiments, but show that the observation of an elevated effective critical field can mainly be attributed to changes in the momentum-space distribution of runaways, and only to a lesser extent to a de facto change in the critical field.

  13. Study on delayed cracking of conductive notch under electric field in PZT-5H ferroelectric ceramics

    Institute of Scientific and Technical Information of China (English)

    QIAO Guangli; SU Yanjing; QIAO Lijie; CHU Wuyang

    2006-01-01

    Electric-field-induced delay cracking of conducting notch in PZT-5H ferroelectric ceramics has been studied using a compact specimen with a notch filled in conductive silver paste. The critical electric field that induces instant failure of the PZT-5H specimen is shown to be EF = 14.7(3.2 kV/cm. When an electric field lower than EF, but higher than EDF = 9.9 kV/cm was applied, a micro-crack formed at the conductive notch tip instantly, propagating slowly until the specimen failure. When the electric field was lower than EDF, the micro-crack propagated a short distance, and then stopped. When the electric field was lower than EK=4.9 kV/cm, no cracks formed at the conductive notch tip instantly, however, a delay micro-crack would form and propagate. When the electric field was lower than EDK=2.4 kV/cm, no cracks formed and delay propagation occurred. A model for electric charge emission and concentration at a conductive notch is proposed to explain the delay cracking of conducting notch.

  14. Aligned Single Wall Carbon Nanotube Polymer Composites Using an Electric Field

    Science.gov (United States)

    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.

  15. Trends in the electric field enhancement of dielectronic recombination cross sections

    International Nuclear Information System (INIS)

    The effect of external electric fields on the dielectronic recombination cross section of selected ions has been studied in the configuration-average, distorted wave approximation. By applying the linear-Stark approximation to the doubly-excited Rydberg states formed from resonant recombination, we examine the systematics of field-mixing effects on dielectronic recombination and determine the maximum field enhancement of dielectronic recombination cross sections. 8 references, 6 figures, 3 tables

  16. Effect of electric field on the photoluminescence intensity of single CdSe nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Park, So-Jung; Link, Stephan; Miller, William L.; Gesquiere, Andre [Department of Chemistry and Biochemistry and the Center for Nano- and Molecular Science and Technology, University of Texas, Austin, TX 78712 (United States); Barbara, Paul F. [Department of Chemistry and Biochemistry and the Center for Nano- and Molecular Science and Technology, University of Texas, Austin, TX 78712 (United States)], E-mail: p.barbara@mail.utexas.edu

    2007-11-15

    An investigation of the effect of an applied electric field on the photoluminescence (PL) intensity of single CdSe nanocrystals has revealed a measurable field induced PL modulation for a large fraction of the nanocrystals studied. The field induced intensity modulation characteristics (i.e. modulation sign and depth) were observed to vary from particle to particle, and even for different time periods for the same particle in many cases. Simultaneous intensity and frequency resolved PL measurement show that the PL intensity modulation is in fact due to an electric field effect on the PL quantum yield. The results are consistent with a model in which the energies of surface charge trapping sites are modulated by the applied electric field, causing in turn a modulation of the rates of exciton quenching by these sites. The complex observed field effects can be explained by the superposition of the applied and internal electric fields due to deeply trapped charges on the surface of the nanoparticle.

  17. Evolution of Spiral Waves under Modulated Electric Fields

    Institute of Scientific and Technical Information of China (English)

    MA Jun; YING He-Ping; PAN Guo-Wei; PU Zhong-Sheng

    2005-01-01

    @@ Spirals generated from the excitable media within the Barkley model is investigated under the gradient electric fields by a numerical simulation. The spiral drift and spiral break up are observed when the amplitude of the electric fields is modulated by a constant signal or a chaotic signal. It is also verified that, even in the presence of the white noise, the whole system can reach homogeneous states after the spiral breakup, by using an adaptive strategy.

  18. Dynamics of a nanowire superlattice in an ac electric field

    OpenAIRE

    Zhang, Aizhen; Voon, L. C. Lew Yan; M. Willatzen

    2005-01-01

    With a one-band envelope function theory, we investigate the dynamics of a finite nanowire superlattice driven by an ac electric field by solving numerically the time-dependent Schroedinger equation. We find that for an ac electric field resonant with two energy levels located in two different minibands, the coherent dynamics in nanowire superlattices is much more complex as compared to the standard two-level description. Depending on the energy levels involved in the transitions, the coheren...

  19. Ionizing gas breakdown waves in strong electric fields.

    Science.gov (United States)

    Klingbeil, R.; Tidman, D. A.; Fernsler, R. F.

    1972-01-01

    A previous analysis by Albright and Tidman (1972) of the structure of an ionizing potential wave driven through a dense gas by a strong electric field is extended to include atomic structure details of the background atoms and radiative effects, especially, photoionization. It is found that photoionization plays an important role in avalanche propagation. Velocities, electron densities, and temperatures are presented as a function of electric field for both negative and positive breakdown waves in nitrogen.

  20. Electric field in media with power-law spatial dispersion

    Science.gov (United States)

    Tarasov, Vasily E.

    2016-04-01

    In this paper, we consider electric fields in media with power-law spatial dispersion (PLSD). Spatial dispersion means that the absolute permittivity of the media depends on the wave vector. Power-law type of this dispersion is described by derivatives and integrals of non-integer orders. We consider electric fields of point charge and dipole in media with PLSD, infinite charged wire, uniformly charged disk, capacitance of spherical capacitor and multipole expansion for PLSD-media.

  1. Structural characterization of electric-field assisted dip-coating of gold nanoparticles on silicon

    Energy Technology Data Exchange (ETDEWEB)

    Dushaq, Ghada H.; Alkhatib, Amro; Rasras, Mahmoud S.; Nayfeh, Ammar M. [Institute Center for microsystem engineering (iMicro), Department of Electrical Engineering and Computer Science (EECS), Masdar Institute of Science and Technology, PO Box. 54224, Abu Dhabi (United Arab Emirates)

    2015-09-15

    We report the effect of applying an electric field on the surface coverage of 40nm gold colloidal nanoparticles on silicon wafer using dip-coating and electrochemical cell set up. By applying electric field during the dip-coating of silicon wafer in a solution of gold nano particles (GNP) the surface coverage increased by 10% when the electric field varied from 5V/cm to 25V/cm at fixed deposition time of 90s. Ultra High Resolution Scanning Electron Microscopy (HRSEM) images shows that the particle agglomeration becomes more noticeable at higher electric field and as the deposition time increases from 90 s to 20 min a thin film of gold is achieved. Moreover, the results are discussed in terms of chemical bonding, electrostatic force and electrophoretic mobility of Au nano particles during the electric field enhanced deposition on the Si surface. Applied voltage, time of dipping, concentration of the aqueous solution, and particles zeta potential are all can be controlled to enhance the uniformity and particles profile on the silicon surface.

  2. Structural characterization of electric-field assisted dip-coating of gold nanoparticles on silicon

    Directory of Open Access Journals (Sweden)

    Ghada H. Dushaq

    2015-09-01

    Full Text Available We report the effect of applying an electric field on the surface coverage of 40nm gold colloidal nanoparticles on silicon wafer using dip-coating and electrochemical cell set up. By applying electric field during the dip-coating of silicon wafer in a solution of gold nano particles (GNP the surface coverage increased by 10% when the electric field varied from 5V/cm to 25V/cm at fixed deposition time of 90s. Ultra High Resolution Scanning Electron Microscopy (HRSEM images shows that the particle agglomeration becomes more noticeable at higher electric field and as the deposition time increases from 90 s to 20 min a thin film of gold is achieved. Moreover, the results are discussed in terms of chemical bonding, electrostatic force and electrophoretic mobility of Au nano particles during the electric field enhanced deposition on the Si surface. Applied voltage, time of dipping, concentration of the aqueous solution, and particles zeta potential are all can be controlled to enhance the uniformity and particles profile on the silicon surface.

  3. Structural characterization of electric-field assisted dip-coating of gold nanoparticles on silicon

    International Nuclear Information System (INIS)

    We report the effect of applying an electric field on the surface coverage of 40nm gold colloidal nanoparticles on silicon wafer using dip-coating and electrochemical cell set up. By applying electric field during the dip-coating of silicon wafer in a solution of gold nano particles (GNP) the surface coverage increased by 10% when the electric field varied from 5V/cm to 25V/cm at fixed deposition time of 90s. Ultra High Resolution Scanning Electron Microscopy (HRSEM) images shows that the particle agglomeration becomes more noticeable at higher electric field and as the deposition time increases from 90 s to 20 min a thin film of gold is achieved. Moreover, the results are discussed in terms of chemical bonding, electrostatic force and electrophoretic mobility of Au nano particles during the electric field enhanced deposition on the Si surface. Applied voltage, time of dipping, concentration of the aqueous solution, and particles zeta potential are all can be controlled to enhance the uniformity and particles profile on the silicon surface

  4. Structural characterization of electric-field assisted dip-coating of gold nanoparticles on silicon

    Science.gov (United States)

    Dushaq, Ghada H.; Alkhatib, Amro; Rasras, Mahmoud S.; Nayfeh, Ammar M.

    2015-09-01

    We report the effect of applying an electric field on the surface coverage of 40nm gold colloidal nanoparticles on silicon wafer using dip-coating and electrochemical cell set up. By applying electric field during the dip-coating of silicon wafer in a solution of gold nano particles (GNP) the surface coverage increased by 10% when the electric field varied from 5V/cm to 25V/cm at fixed deposition time of 90s. Ultra High Resolution Scanning Electron Microscopy (HRSEM) images shows that the particle agglomeration becomes more noticeable at higher electric field and as the deposition time increases from 90 s to 20 min a thin film of gold is achieved. Moreover, the results are discussed in terms of chemical bonding, electrostatic force and electrophoretic mobility of Au nano particles during the electric field enhanced deposition on the Si surface. Applied voltage, time of dipping, concentration of the aqueous solution, and particles zeta potential are all can be controlled to enhance the uniformity and particles profile on the silicon surface.

  5. Visualization on the behavior of nanoparticles in magnetic fluids under the electric field

    Science.gov (United States)

    Lee, W.-H.; Lee, J.-C.

    2013-02-01

    The dielectric breakdown characteristics of magnetic fluids can be influenced by the magnetic nanoparticles included because their properties should be affected by the applied electric field. Based on measuring the dielectric breakdown voltage of magnetic fluids, we found that it is higher than that of the pure transformer oil in the case of the specific volume concentrations of magnetic nanoparticles. It is known from a numerical simulation that the conductive nanoparticles might behavior as electron scavengers in the electrically stressed magnetic fluids and change fast electrons into slowly negative charged nanoparticles for the electrical breakdown. In this study, we focus on the motion of magnetic nanoparticles in the fluids under the electric field applied by the visualization using a microchannel and an optical microscope.

  6. Static electric field enhancement in nanoscale structures

    Science.gov (United States)

    Lepetit, Bruno; Lemoine, Didier; Márquez-Mijares, Maykel

    2016-08-01

    We study the effect of local atomic- and nano-scale protrusions on field emission and, in particular, on the local field enhancement which plays a key role as known from the Fowler-Nordheim model of electronic emission. We study atomic size defects which consist of right angle steps forming an infinite length staircase on a tungsten surface. This structure is embedded in a 1 GV/m ambient electrostatic field. We perform calculations based upon density functional theory in order to characterize the total and induced electronic densities as well as the local electrostatic fields taking into account the detailed atomic structure of the metal. We show how the results must be processed to become comparable with those of a simple homogeneous tungsten sheet electrostatic model. We also describe an innovative procedure to extrapolate our results to nanoscale defects of larger sizes, which relies on the microscopic findings to guide, tune, and improve the homogeneous metal model, thus gaining predictive power. Furthermore, we evidence analytical power laws for the field enhancement characterization. The main physics-wise outcome of this analysis is that limited field enhancement is to be expected from atomic- and nano-scale defects.

  7. Large amplitude middle atmospheric electric fields - Fact or fiction?

    Science.gov (United States)

    Kelley, M. C.; Siefring, C. L.; Pfaff, R. F., Jr.

    1983-01-01

    An analysis of the measurements of large apparent dc fields in the middle atmosphere, previously gathered by two sounding rockets, shows these fields to be spurious. In the case of one of the rockets, the evidence presented suggests that the measured electric fields, aligned with the rocket's velocity vector, may be due to a negatively charged wake. A comparison of measurements made by various electric field booms also suggests that the insulating boom coatings in one experiment may have affected the results obtained. It is recommended that insulating coatings should not be used at mesospheric altitudes, because of the detrimental effects that frictional charging may have.

  8. Spiking patterns of a hippocampus model in electric fields

    International Nuclear Information System (INIS)

    We develop a model of CA3 neurons embedded in a resistive array to mimic the effects of electric fields from a new perspective. Effects of DC and sinusoidal electric fields on firing patterns in CA3 neurons are investigated in this study. The firing patterns can be switched from no firing pattern to burst or from burst to fast periodic firing pattern with the increase of DC electric field intensity. It is also found that the firing activities are sensitive to the frequency and amplitude of the sinusoidal electric field. Different phase-locking states and chaotic firing regions are observed in the parameter space of frequency and amplitude. These findings are qualitatively in accordance with the results of relevant experimental and numerical studies. It is implied that the external or endogenous electric field can modulate the neural code in the brain. Furthermore, it is helpful to develop control strategies based on electric fields to control neural diseases such as epilepsy. (interdisciplinary physics and related areas of science and technology)

  9. Spiking patterns of a hippocampus model in electric fields

    Institute of Scientific and Technical Information of China (English)

    Men Cong; Wang Jiang; Qin Ying-Mei; Wei Xi-Le; Che Yan-Qiu; Deng Bin

    2011-01-01

    We develop a model of CA3 neurons embedded in a resistive array to mimic the effects of electric fields from a new perspective.Effects of DC and sinusoidal electric fields on firing patterns in CA3 neurons are investigated in this study.The firing patterns can be switched from no firing pattern to burst or from burst to fast periodic firing pattern with the increase of DC electric field intensity.It is also found that the firing activities are sensitive to the frequency and amplitude of the sinusoidal electric field.Different phase-locking states and chaotic firing regions are observed in the parameter space of frequency and amplitude.These findings are qualitatively in accordance with the results of relevant experimental and numerical studies.It is implied that the external or endogenous electric field can modulate the neural code in the brain.Furthermore,it is helpful to develop control strategies based on electric fields to control neural diseases such as epilepsy.

  10. A novel high-sensitivity electrostatic biased electric field sensor

    International Nuclear Information System (INIS)

    In this paper, an electric field sensor (EFS) with high sensitivity is proposed for low-frequency weak-strength ac electric field (E-field) measurements. The EFS is based on a piezoelectric cantilever biased by a strong electrostatic field. The electrostatic bias can enhance the electric field force of a weak ac E-field, thus the cantilever can oscillate in a weak ac E-field and the device sensitivity improves. Theoretical analyses have been established and suggest that a stronger strength of electrostatic field bias would produce a higher sensitivity improvement. In the experiment, a demonstrated sensor consisting of a polyvinylidene fluoride (PVDF) piezoelectric cantilever and a polytetrafluoroethylene (PTFE) electret was built and tested. Instead of extra voltage sources, the PTFE electret was charged to provide the electrostatic field, allowing the EFS a low energy consumption and a simple electric circuit design. The experiment results show good agreement with the simulation. The sensitivity of the cantilever E-field sensor reached 0.84 mV (kV/m)−1 when the surface potential of the electret was  −770 V. (paper)

  11. Ponderomotive Force in the Presence of Electric Fields

    Science.gov (United States)

    Khazanov, G. V.; Krivorutsky, E. N.

    2013-01-01

    This paper presents averaged equations of particle motion in an electromagnetic wave of arbitrary frequency with its wave vector directed along the ambient magnetic field. The particle is also subjected to an E cross B drift and a background electric field slowly changing in space and acting along the magnetic field line. The fields, wave amplitude, and the wave vector depend on the coordinate along the magnetic field line. The derivations of the ponderomotive forces are done by assuming that the drift velocity in the ambient magnetic field is comparable to the particle velocity. Such a scenario leads to new ponderomotive forces, dependent on the wave magnetic field intensity, and, as a result, to the additional energy exchange between the wave and the plasma particles. It is found that the parallel electric field can lead to the change of the particle-wave energy exchange rate comparable to that produced by the previously discussed ponderomotive forces.

  12. Electric Field Screening with Backflow at Pulsar Polar Cap

    Science.gov (United States)

    Kisaka, Shota; Asano, Katsuaki; Terasawa, Toshio

    2016-09-01

    Recent γ-ray observations suggest that particle acceleration occurs at the outer region of the pulsar magnetosphere. The magnetic field lines in the outer acceleration region (OAR) are connected to the neutron star surface (NSS). If copious electron-positron pairs are produced near the NSS, such pairs flow into the OAR and screen the electric field there. To activate the OAR, the electromagnetic cascade due to the electric field near the NSS should be suppressed. However, since a return current is expected along the field lines through the OAR, the outflow extracted from the NSS alone cannot screen the electric field just above the NSS. In this paper, we analytically and numerically study the electric field screening at the NSS, taking into account the effects of the backflowing particles from the OAR. In certain limited cases, the electric field is screened without significant pair cascade if only ultra-relativistic particles (γ \\gg 1) flow back to the NSS. On the other hand, if electron-positron pairs with a significant number density and mildly relativistic temperature, expected to distribute in a wide region of the magnetosphere, flow back to the NSS, these particles adjust the current and charge densities so that the electric field can be screened without pair cascade. We obtain the condition needed for the number density of particles to screen the electric field at the NSS. We also find that in the ion-extracted case from the NSS, bunches of particles are ejected to the outer region quasi-periodically, which is a possible mechanism of observed radio emission.

  13. Radiation-induced solidification of ionic liquid under extreme electric field

    Science.gov (United States)

    Terhune, Kurt J.; King, Lyon B.; He, Kai; Cumings, John

    2016-09-01

    An extreme electric field on the order of 1010 V m‑1 was applied to the free surface of an ionic liquid to cause electric-field-induced evaporation of molecular ions from the liquid. The point of ion emission was observed in situ using a TEM. The resulting electrospray emission process was observed to create nanoscale high-aspect-ratio dendritic features that were aligned with the direction of the electric field. Upon removal of the stressing field the features were seen to remain, indicating that the ionic liquid residue was solidified or gelled. Similar electrospray experiments performed in a field-emission scanning electron microscope revealed that the features are created when the high-energy electron beam damages the molecular structure of the ionic liquid. While the electric field does not play a direct role in the fluid modification, the electric stress was critical in detecting the liquid property change. It is only because the electric stress mechanically elongated the fluid during the electrospray process and these obviously non-liquid structures persisted when the field was removed that the damage was evident. This evidence of ionic liquid radiation damage may have significant bearing on electrospray devices where it is possible to produce high-energy secondary electrons through surface impacts of emitted ions downstream of the emitter. Any such impacts that are in close proximity could see reflected secondary electrons impact the emitter causing gelling of the ionic liquid.

  14. Radiation-induced solidification of ionic liquid under extreme electric field

    Science.gov (United States)

    Terhune, Kurt J.; King, Lyon B.; He, Kai; Cumings, John

    2016-09-01

    An extreme electric field on the order of 1010 V m-1 was applied to the free surface of an ionic liquid to cause electric-field-induced evaporation of molecular ions from the liquid. The point of ion emission was observed in situ using a TEM. The resulting electrospray emission process was observed to create nanoscale high-aspect-ratio dendritic features that were aligned with the direction of the electric field. Upon removal of the stressing field the features were seen to remain, indicating that the ionic liquid residue was solidified or gelled. Similar electrospray experiments performed in a field-emission scanning electron microscope revealed that the features are created when the high-energy electron beam damages the molecular structure of the ionic liquid. While the electric field does not play a direct role in the fluid modification, the electric stress was critical in detecting the liquid property change. It is only because the electric stress mechanically elongated the fluid during the electrospray process and these obviously non-liquid structures persisted when the field was removed that the damage was evident. This evidence of ionic liquid radiation damage may have significant bearing on electrospray devices where it is possible to produce high-energy secondary electrons through surface impacts of emitted ions downstream of the emitter. Any such impacts that are in close proximity could see reflected secondary electrons impact the emitter causing gelling of the ionic liquid.

  15. Effect of an intersection of carbon nanotubes on the carrier accumulation under an external electric field

    Science.gov (United States)

    Kochi, Taketo; Okada, Susumu

    2016-08-01

    We studied the electronic structure of semiconducting carbon nanotube (CNT) thin films, in which CNTs intersect each other, under an external electric field, using first-principles total-energy calculations within the framework of the density functional theory. Our calculations show that the distribution of accumulated carriers strongly depends on the CNT species, their mutual arrangement with respect to the electrode, and carrier concentrations. Under particular conditions, an induced electric field between the CNTs is opposite to the applied field. We also showed that the quantum capacitance of the CNT thin films depends on the arrangement of the CNTs relative to the electrode.

  16. Electric field induced charge transfer through single and double-stranded DNA polymer molecules

    OpenAIRE

    Ramos, Marta M. D.; Correia, Helena M. G.

    2011-01-01

    The charge transfer through single-stranded and double-stranded DNA polymer molecules has been the subject of numerous experimental and theoretical studies concerning their applications in molecular electronics. However, the underlying mechanisms responsible for their different electrical conductivity observed in the experiments are poorly understood. Here we use a self-consistent quantum molecular dynamics method to study the effect of an applied electric field along the molecular axis on ch...

  17. Low magnetic Johnson noise electric field plates for precision measurement

    CERN Document Server

    Rabey, I M; Hinds, E A; Sauer, B E

    2016-01-01

    We describe a parallel pair of high voltage electric field plates designed and constructed to minimise magnetic Johnson noise. They are formed by laminating glass substrates with commercially available polyimide (Kapton) tape, covered with a thin gold film. Tested in vacuum, the outgassing rate is less than $5\\times10^{-5}$ mbar.l/s. The plates have been operated at electric fields up to 8.3 kV/cm, when the leakage current is at most a few hundred pA. The design is discussed in the context of a molecular spin precession experiment to measure the permanent electric dipole moment of the electron.

  18. Soybean Hydrophobic Protein Response to External Electric Field: A Molecular Modeling Approach

    Directory of Open Access Journals (Sweden)

    Vijaya Raghavan

    2013-02-01

    Full Text Available The molecular dynamic (MD modeling approach was applied to evaluate the effect of an external electric field on soybean hydrophobic protein and surface properties. Nominal electric field strengths of 0.002 V/nm and 0.004 V/nm had no major effect on the structure and surface properties of the protein isolate but the higher electric field strength of 3 V/nm significantly affected the protein conformation and solvent accessible surface area. The response of protein isolate to various external field stresses demonstrated that it is necessary to gain insight into protein dynamics under electromagnetic fields in order to be able to develop the techniques utilizing them for food processing and other biological applications.

  19. Influence of viscosity of the medium on the disposition of carbon nanotubes anisotropic structures formation induced by electric field

    International Nuclear Information System (INIS)

    To obtain carbon nanotubes (CNT)-polymer composites with anisotropic physical properties an electric field application can be used. This investigation considers factors of CNT anisotropic distribution formation induced by electric field and consideration is supported with experimental results where some factors were varied. In the article an influence of magnitude and type of electric field and time of processing by electric field on CNT anisotropic structures formation in polymer mediums of different viscosities (oil, epoxy resins) is investigated. The aim of this work was to examine the CNT structuration process induced by electric field in viscous mediums and to find out the most optimal conditions of preparation of polymer/carbon composite materials (CM) with specified distribution of carbon filler induced by electric field. Scoping on polymer/carbon CM structuration was conducted by optical microscopy method. It was found that the main factors during CNT network formation are the type and viscosity of polymer binder and applied electric field parameters. It was observed that for high viscous polymer CNT network formation is unfeasible even at high applied electric field strength. But also for low viscous medium at relatively low electric field strength the CNT network formation is complicated too. And it was seen from optical observation that a type of the polymer variation causes different response of network form under the same experimental conditions. These distinctions are considered in the article

  20. Electric field-induced softening of alkali silicate glasses

    Energy Technology Data Exchange (ETDEWEB)

    McLaren, C.; Heffner, W.; Jain, H. [Department of Materials Science and Engineering, Lehigh University, Bethlehem, Pennsylvania 18015 (United States); Tessarollo, R.; Raj, R. [Department of Mechanical Engineering, University of Colorado at Boulder, Boulder, Colorado 80309 (United States)

    2015-11-02

    Motivated by the advantages of two-electrode flash sintering over normal sintering, we have investigated the effect of an external electric field on the viscosity of glass. The results show remarkable electric field-induced softening (EFIS), as application of DC field significantly lowers the softening temperature of glass. To establish the origin of EFIS, the effect is compared for single vs. mixed-alkali silicate glasses with fixed mole percentage of the alkali ions such that the mobility of alkali ions is greatly reduced while the basic network structure does not change much. The sodium silicate and lithium-sodium mixed alkali silicate glasses were tested mechanically in situ under compression in external electric field ranging from 0 to 250 V/cm in specially designed equipment. A comparison of data for different compositions indicates a complex mechanical response, which is observed as field-induced viscous flow due to a combination of Joule heating, electrolysis and dielectric breakdown.

  1. Distribution of electric field for carbon nanotube assembly: Experiments (Ⅱ)

    Institute of Scientific and Technical Information of China (English)

    Soongeun KWON; Soo-Hyun KIM; Kwang-ho KIM; Myung-chang KANG; Hyung-woo LEE

    2011-01-01

    The distribution effect of electric field on the alignment and attachment of carbon nanotubes (CNTs) were investigated.The experimental results were compared with the simulation results according to three different shaped electrodes. In previous simulation, the round shaped electrodes were expected to be more effective for aligning and attaching a single CNT between two electrodes than conical or rectangular shaped electrodes. To verify the simulation results, three different shaped electrodes were introduced and a single multi-walled carbon nanotube (MWNT) was attached. The optimal conditions for aligning and attaching MWNTs such as the frequency, applied voltage and concentration of MWNTs solution were investigated. Through repeated experiments, frequency of 100 kHz-10 MHz, applied voltage of 0.3-1.3 Vrms/μm, concentration of 5 μg/mL in MWNTs solution were obtained as a possible condition range to attach MWNTs. Under these conditions, the yield of MWNTs attachment between two electrodes was up to 70%. In previous simulation, furthermore, it was verified that the size of the stable or quasi-stable region made CNTs aligned and attached on different shaped electrodes from the comparison of the experimental and simulation results. Most single MWNT attachment was accomplished on the round shaped electrodes.

  2. New Method for Solving Inductive Electric Fields in the Ionosphere

    Science.gov (United States)

    Vanhamäki, H.

    2005-12-01

    We present a new method for calculating inductive electric fields in the ionosphere. It is well established that on large scales the ionospheric electric field is a potential field. This is understandable, since the temporal variations of large scale current systems are generally quite slow, in the timescales of several minutes, so inductive effects should be small. However, studies of Alfven wave reflection have indicated that in some situations inductive phenomena could well play a significant role in the reflection process, and thus modify the nature of ionosphere-magnetosphere coupling. The input to our calculation method are the time series of the potential part of the ionospheric electric field together with the Hall and Pedersen conductances. The output is the time series of the induced rotational part of the ionospheric electric field. The calculation method works in the time-domain and can be used with non-uniform, time-dependent conductances. In addition no particular symmetry requirements are imposed on the input potential electric field. The presented method makes use of special non-local vector basis functions called Cartesian Elementary Current Systems (CECS). This vector basis offers a convenient way of representing curl-free and divergence-free parts of 2-dimensional vector fields and makes it possible to solve the induction problem using simple linear algebra. The new calculation method is validated by comparing it with previously published results for Alfven wave reflection from uniformly conducting ionosphere.

  3. Ion-cage interpretation for the structural and dynamic changes of ionic liquids under an external electric field.

    Science.gov (United States)

    Shi, Rui; Wang, Yanting

    2013-05-01

    In many applications, ionic liquids (ILs) work in a nonequilibrium steady state driven by an external electric field. However, how the electric field changes the structure and dynamics of ILs and its underlying mechanism still remain poorly understood. In this paper, coarse-grained molecular dynamics simulations were performed to investigate the structure and dynamics of 1-ethyl-3-methylimidazolium nitrate ([EMIm][NO3]) under a static electric field. The ion cage structure was found to play an essential role in determining the structural and dynamic properties of the IL system. With a weak or moderate electric field (0-10(7) V/m), the external electric field is too weak to modify the ion cage structure in an influential way and thus the changes of structural and dynamic properties are negligible. With a strong electric field (10(7)-10(9) V/m) applied, ion cages expand and deform apparently, leading to the increase of ion mobility and self-diffusion coefficient with electric field, and the self-diffusion of ions along the electric field becomes faster than the other two directions due to the anisotropic deformation of ion cages. In addition, the Einstein relation connecting diffusion and mobility breaks down at strong electric fields, and it also breaks down for a single ion species even at moderate electric fields (linear-response region).

  4. EFFECTS OF STATIC ELECTRIC FIELD ON THE FRACTURE BEHAVIOR OF PIEZOELECTRIC CERAMICS

    Institute of Scientific and Technical Information of China (English)

    Tong-Yi Zhang

    2002-01-01

    The paper gives an overview on experimental observations of thefailure behavior of electrically insulating and conducting cracks in piezoelectric ce-ramics. The experiments include the indentation fracture test, the bending test onsmooth samples, and the fracture test on pre-notched (or pre-cracked) compact ten-sion samples. For electrically insulating cracks, the experimental results show a com-plicated fracture behavior under electrical and mechanical loading. Fracture dataare much scattered when a static electric field is applied. A statistically based frac-ture criterion is required. For electrically conducting cracks, the experimental resultsdemonstrate that static electric fields can fracture poled and depoled lead zirconatetitanate ceramics and that the concepts of fracture mechanics can be used to mea-sure the electrical fracture toughness. Furthermore, the electrical fracture toughnessis much higher than the mechanical fracture toughness. The highly electrical fracturetoughness arises from the greater energy dissipation around the conductive crack tipunder purely electric loading, which is impossible under mechanical loading in thebrittle ceramics.

  5. Electric field sensor based on cholesteric liquid crystal Fabry-Perot etalon

    Science.gov (United States)

    Ko, Myeong Ock; Kim, Sung-Jo; Kim, Jong-Hyun; Lee, Bong Wan; Jeon, Min Yong

    2015-09-01

    We propose an electric field sensor using a cholesteric liquid crystal (CLC) Fabry-Perot etalon and a broadband optical source. The CLC cell consists of glass substrates, polyimide layers, electrodes, and CLC layer. There is a threshold behavior for CLC cell and no change in the transmitted wavelength occurs until a threshold value. The threshold value is 0.8 V/μm for fabricated CLC cell in this experiment. The transmitted or reflected wavelength from the CLC Fabry-Perot etalon depends on the applied electric field. The valley wavelengths of the transmitted light from the CLC device are linearly increased from 1303 nm to 1317 nm as the applied electric field to the CLC device is increased from 0.8 V/μm to 1.9 V/μm.

  6. Electric-Field Induced Activation of Dark Excitonic States in Carbon Nanotubes.

    Science.gov (United States)

    Uda, T; Yoshida, M; Ishii, A; Kato, Y K

    2016-04-13

    Electrical activation of optical transitions to parity-forbidden dark excitonic states in individual carbon nanotubes is reported. We examine electric-field effects on various excitonic states by simultaneously measuring photocurrent and photoluminescence. As the applied field increases, we observe an emergence of new absorption peaks in the excitation spectra. From the diameter dependence of the energy separation between the new peaks and the ground state of E11 excitons, we attribute the peaks to the dark excited states which became optically active due to the applied field. Field-induced exciton dissociation can explain the photocurrent threshold field, and the edge of the E11 continuum states has been identified by extrapolating to zero threshold. PMID:26999284

  7. A New Rotation Phenomena of Cells Induced by Homegeneous Electric Field

    Science.gov (United States)

    Hatakeyama, Toyomasa; Yagi, Hiroshi

    1990-05-01

    When at least two plant protoplasts are located close to each other under homogeneous electric field, almost all of the cells rotate in the vicinity of its frequency of 10 kHz and specific cells in the vicinity of 10 MHz. The first rotation occurs in the plane constituted by the connecting line between two cells and the applied electric field line. This angular velocity increases with the square of the field strength. On the other hand, the second rotation or new rotation occurs in any plane and its angular velocity complicatedly depends on the field strength. Furthermore, when two cells are arranged in such a way that their connecting line is parallel to the applied field, the second rotation occurs but the first does not. The distinctive feature of the second rotation can be explained by the anisotropic dielectric in the cell due to the shape of its vacuole.

  8. Determinants of the electric field during transcranial direct current stimulation

    DEFF Research Database (Denmark)

    Opitz, Alexander; Paulus, Walter; Will, Susanne;

    2015-01-01

    Transcranial direct current stimulation (tDCS) causes a complex spatial distribution of the electric current flow in the head which hampers the accurate localization of the stimulated brain areas. In this study we show how various anatomical features systematically shape the electric field...... distribution in the brain during tDCS. We constructed anatomically realistic finite element (FEM) models of two individual heads including conductivity anisotropy and different skull layers. We simulated a widely employed electrode montage to induce motor cortex plasticity and moved the stimulating electrode...... over the motor cortex in small steps to examine the resulting changes of the electric field distribution in the underlying cortex. We examined the effect of skull thickness and composition on the passing currents showing that thinner skull regions lead to higher electric field strengths. This effect...

  9. Limiting electric fields of HVDC overhead power lines.

    Science.gov (United States)

    Leitgeb, N

    2014-05-01

    As a consequence of the increased use of renewable energy and the now long distances between energy generation and consumption, in Europe, electric power transfer by high-voltage (HV) direct current (DC) overhead power lines gains increasing importance. Thousands of kilometers of them are going to be built within the next years. However, existing guidelines and regulations do not yet contain recommendations to limit static electric fields, which are one of the most important criteria for HVDC overhead power lines in terms of tower design, span width and ground clearance. Based on theoretical and experimental data, in this article, static electric fields associated with adverse health effects are analysed and various criteria are derived for limiting static electric field strengths.

  10. Electric field by pick-up ions and electrons

    Science.gov (United States)

    Yamauchi, Masatoshi; Behar, Etienne; Nilsson, Hans; Holmstrom, Mats

    2016-04-01

    Observations by the Rosetta Plasma Consortium (RPC) showed increasing distortion of the solar wind flow as Rosetta approached the Sun, i.e., as the density of the newly born ions increased. This indicates azimuthal momentum transfer from the solar wind to the newly born ions because they are displaced by the solar wind electric field up to the ion gyroradius this the solar wind velocity, and conservation of the momentum (center of the mass) makes the solar wind to azimuthally shift by "counter action" of these pick-up ion motions. To understand this azimuthal momentum transfer, it is inevitable to model the electric field by the displacement of these pick-up ions and electrons. Although the E×B drift does not make charge separation when the scale size is larger than the ion gyroradius, ions and electrons move in the opposite direction to each other within the short distance up to a gyroradius, and therefore, the charge separation occurs. Thus, the newly-ionized neutrals (ion-electron pairs) create the electric field in the opposite (shielding) direction to the solar wind electric field (like the ionopause of Venus and Mars). However, such a newly induced "shielding" electric field will simultaneously be weakened by the solar wind electrons because the solar wind is also moved by this shielding electric field to reduce it, in the same way as the plasma oscillation (time scale of about 10‑4 s). In other words, the solar wind tries to maintain the solar wind electric field as far as the momentum allows. These two opposite effects must be combined when modelling the azimuthal electric field, and resultant ion/electron motions within a gyroradius, like the case for ROSETTA. Furthermore, the effect of the induced electric field by the pick-up ions and electrons will be different when the newly born ions are created as the result of photo-ionization and of the charge exchange because the electron effect is different between them. In the presentation, we model the

  11. Electric fields, weighting fields, signals and charge diffusion in detectors including resistive materials

    OpenAIRE

    Riegler, Werner

    2016-01-01

    In this report we discuss static and time dependent electric fields in detector geometries with an arbitrary number of parallel layers of a given permittivity and weak conductivity. We derive the Green's functions i.e. the field of a point charge, as well as the weighting fields for readout pads and readout strips in these geometries. The effect of 'bulk' resistivity on electric fields and signals is investigated. The spreading of charge on thin resistive layers is also discussed in detail, a...

  12. Time development of electric fields and currents in space plasmas

    Directory of Open Access Journals (Sweden)

    A. T. Y. Lui

    2006-05-01

    Full Text Available Two different approaches, referred to as Bu and Ej, can be used to examine the time development of electric fields and currents in space plasmas based on the fundamental laws of physics. From the Bu approach, the required equation involves the generalized Ohm's law with some simplifying assumptions. From the Ej approach, the required equation can be derived from the equation of particle motion, coupled self-consistently with Maxwell's equation, and the definition of electric current density. Recently, some strong statements against the Ej approach have been made. In this paper, we evaluate these statements by discussing (1 some limitations of the Bu approach in solving the time development of electric fields and currents, (2 the procedure in calculating self-consistently the time development of the electric current in space plasmas without taking the curl of the magnetic field in some cases, and (3 the dependency of the time development of magnetic field on electric current. It is concluded that the Ej approach can be useful to understand some magnetospheric problems. In particular, statements about the change of electric current are valid theoretical explanations of change in magnetic field during substorms.

  13. Tuning the electronic properties of single-walled SiC nanotubes by external electric field

    Science.gov (United States)

    Shi, Wenwu; Wu, Shiyun; Wang, Zhiguo

    2016-07-01

    The electronic properties of SiC nanotubes (SiCNTs) under external transverse electric field were investigated using density functional theory. The pristine SiCNTs were semiconductors with band-gaps of 2.03, 2.17 and 2.25 eV for (6,6), (8,8) and (10,10) SiCNTs, respectively. It was found the band gaps was reduced with the external transverse electric filed applied. The (8,8) and (10,10) SiCNTs changed from semiconductor to metals as the intensity of electric field reached 0.7 and 0.5 V/Å. The results indicate that the electronic properties of SiCNTs can be tuned by the transvers electric field with integrality of the nanotubes.

  14. Relation between magnetic fields and electric currents in plasmas

    Directory of Open Access Journals (Sweden)

    V. M. Vasyliunas

    2005-10-01

    Full Text Available Maxwell's equations allow the magnetic field B to be calculated if the electric current density J is assumed to be completely known as a function of space and time. The charged particles that constitute the current, however, are subject to Newton's laws as well, and J can be changed by forces acting on charged particles. Particularly in plasmas, where the concentration of charged particles is high, the effect of the electromagnetic field calculated from a given J on J itself cannot be ignored. Whereas in ordinary laboratory physics one is accustomed to take J as primary and B as derived from J, it is often asserted that in plasmas B should be viewed as primary and J as derived from B simply as (c/4π∇×B. Here I investigate the relation between ∇×B and J in the same terms and by the same method as previously applied to the MHD relation between the electric field and the plasma bulk flow vmv2001: assume that one but not the other is present initially, and calculate what happens. The result is that, for configurations with spatial scales much larger than the electron inertial length λe, a given ∇×B produces the corresponding J, while a given J does not produce any ∇×B but disappears instead. The reason for this can be understood by noting that ∇×B≠4π/cJ implies a time-varying electric field (displacement current which acts to change both terms (in order to bring them toward equality; the changes in the two terms, however, proceed on different time scales, light travel time for B and electron plasma period for J, and clearly the term changing much more slowly is the one that survives. (By definition, the two time scales are equal at λe. On larger scales, the evolution of B (and hence also of ∇×B is governed by

  15. Elastic constant of Dendrobium protoplasts in AC electric fields

    Directory of Open Access Journals (Sweden)

    Pikul Wanichapichart

    2002-11-01

    Full Text Available This work reports elongation of Dendrobium protoplasts in an ac electric field between two cylindrical electrodes. A protoplast firstly was translated towards an electrode by dielectrophoretic force in 17 kV.m-1 field strength at 1 MHz, and secondly it was elongated due to an interaction between an induced electric dipole (μ and the electric field (E. Protoplast elongation was observed by varying both the field strength at 30, 45, 60, and 85 kV.m-1 and field frequency at 0.5, 1, 5, and 10 MHz. For a given field frequency and field strength, a parameter a/b (major/minor axis was measured as the protoplast elongation.Two-step elongation and restoration phases were observed. The former was completed within 2 minutes of field exposure, and the latter was completed within 15 seconds regardless of the field exposure time between 3 and 20 minutes. The evidence of a complete restoration indicated that the elasticity of the protoplast membrane obeyed Hooke’s law. This study also found that elastic constant k of the membrane varied non-linearly with the field strength. It was found to be from 0.04 to 0.08 mN.m-1, dependent on the field frequency.

  16. Manipulation of two-electron states by the electric field in stacked self-assembled dots

    International Nuclear Information System (INIS)

    A pair of electrons in vertically stacked self-assembled quantum dots is studied and the singlet-triplet energy splitting is calculated in an external electric field using the configuration-interaction method. We show that for double quantum dots the dependence of the singlet energy levels on the electric field involves multiple avoided crossings of three energy levels. The exchange interaction, i.e., the energy difference of the lowest triplet and lowest singlet states, can be tuned by an electric field in a wide range of several tens of meV. For electric fields exceeding a threshold value the exchange interaction becomes a linear function of the field when the two electrons in the singlet state start to occupy the same dot. We also consider non-symmetric confinement, non-perfectly aligned dots, in horizontal as well as vertical field orientation. In a stack of three vertically coupled dots the depth of the confinement in the central dot can be used to enhance the exchange interaction. For a deeper central dot the dependence of the exchange interaction on the electric field is anomalous-it initially decreases when the field is applied in both directions parallel and antiparallel to the axis of the stack. Such a behavior is never observed for a pair of quantum dots

  17. Electric-field control of spin-orbit torque in a magnetically doped topological insulator

    Science.gov (United States)

    Fan, Yabin; Kou, Xufeng; Upadhyaya, Pramey; Shao, Qiming; Pan, Lei; Lang, Murong; Che, Xiaoyu; Tang, Jianshi; Montazeri, Mohammad; Murata, Koichi; Chang, Li-Te; Akyol, Mustafa; Yu, Guoqiang; Nie, Tianxiao; Wong, Kin L.; Liu, Jun; Wang, Yong; Tserkovnyak, Yaroslav; Wang, Kang L.

    2016-04-01

    Electric-field manipulation of magnetic order has proved of both fundamental and technological importance in spintronic devices. So far, electric-field control of ferromagnetism, magnetization and magnetic anisotropy has been explored in various magnetic materials, but the efficient electric-field control of spin-orbit torque (SOT) still remains elusive. Here, we report the effective electric-field control of a giant SOT in a Cr-doped topological insulator (TI) thin film using a top-gate field-effect transistor structure. The SOT strength can be modulated by a factor of four within the accessible gate voltage range, and it shows strong correlation with the spin-polarized surface current in the film. Furthermore, we demonstrate the magnetization switching by scanning gate voltage with constant current and in-plane magnetic field applied in the film. The effective electric-field control of SOT and the giant spin-torque efficiency in Cr-doped TI may lead to the development of energy-efficient gate-controlled spin-torque devices compatible with modern field-effect semiconductor technologies.

  18. Asymmetry of Neoclassical Transport by Dipole Electric Field

    Institute of Scientific and Technical Information of China (English)

    王中天; 王龙

    2004-01-01

    Effects of dipole electric fields on neoclassical transport are studied. Large asymmetry in transport is created. The dipole fields, which are in a negative R-direction, reduce the ion drift, increase electron drift, and change the steps of excursion due to collisions. It is found that different levels of dipole field intensities have different types of transport. For the lowest level of the dipole field, the transport returns to the neoclassical one. For the highest level of the dipole field, the transport is turned to be the turbulence transport similar to the pseudo-classical transport. Experimental data may be corresponded to a large level of the dipole field intensity.

  19. Electric-Field-Induced Superconductivity Detected by Magnetization Measurements of an Electric-Double-Layer Capacitor

    NARCIS (Netherlands)

    Kasahara, Yuichi; Nishijima, Takahiro; Sato, Tatsuya; Takeuchi, Yuki; Ye, Jianting; Yuan, Hongtao; Shimotani, Hidekazu; Iwasa, Yoshihiro

    2011-01-01

    We report evidence for superconductivity induced by the application of strong electric fields onto the surface of a band insulator, ZrNCl, provided by the observation of a shielding diamagnetic signal. We introduced an electric-double-layer capacitor configuration and in situ magnetization measureme

  20. Soot reduction under DC electric fields in counterflow non-premixed laminar ethylene flames

    KAUST Repository

    Park, Daegeun

    2014-04-23

    The effects of DC electric fields on non-premixed ethylene flames in a counterflow burner were studied experimentally with a focus on the reduction of soot particles. The experiment was conducted by connecting a high voltage terminal and a ground terminal to a lower (fuel) and upper (oxidizer) nozzle, respectively. We applied direct current (DC) potentials in a range of -5 kV < Vdc < 5 kV. Uniform electric fields were then generated in the gap between the two nozzles. The experimental conditions were selected to cover both soot formation (SF) and soot formation oxidation (SFO) flames. The flames subjected to the negative electric fields moved toward the fuel nozzle because of an ionic wind due to the Lorentz force acting on the positive ions in the flames. In addition, the yellow luminosity significantly decreased, indicating changes in the sooting characteristics. To analyze the sooting characteristics under the electric fields, planar laser induced incandescence (PLII) and fluorescence (PLIF) techniques were used to visualize the soot, polycyclic aromatic hydrocarbons (PAHs), and OH radicals. The sooting limits in terms of the fuel and oxygen mole fractions were measured. No substantial soot formation due to the effects of the DC electric fields for the tested range of voltages and reactant mole fractions could be identified. The detailed flame behaviors and sooting characteristics under the DC electric fields are discussed. Copyright © Taylor & Francis Group, LLC.

  1. Electric field assisted aerosol assisted chemical vapour deposition of nanostructured metal oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Naik, Anupriya J.T.; Bowman, Christopher; Panjwani, Naitik [Department of Chemistry, University College London, Christopher Ingold Laboratories, 20 Gordon Street, London WC1H OAJ (United Kingdom); Warwick, Michael E.A. [Department of Chemistry, University College London, Christopher Ingold Laboratories, 20 Gordon Street, London WC1H OAJ (United Kingdom); UCL Energy Institute, Central House, 14 Upper Woburn Place, London WC1H 0HY (United Kingdom); Binions, Russell, E-mail: r.binions@qmul.ac.uk [Department of Chemistry, University College London, Christopher Ingold Laboratories, 20 Gordon Street, London WC1H OAJ (United Kingdom); School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom)

    2013-10-01

    Nanostructured thin films of tungsten, vanadium and titanium oxides were deposited on gas sensor substrates from the electric field assisted chemical vapour deposition reaction of tungsten hexaphenoxide, vanadyl acetylacetonate and titanium tetraisopropoxide respectively. The electric fields were generated by applying a potential difference between the inter-digitated electrodes of the gas sensor substrates during the deposition. The deposited films were characterised using scanning electron microscopy, X-ray diffraction and Raman spectroscopy. The application of an electric field, encouraged the formation of interesting and unusual nanostructured morphologies, with a change in scale length and island packing. It was also noted that crystallographic orientation of the films could be controlled as a function of electric field type and strength. The gas sensor properties of the films were also examined; it was found that a two to three fold enhancement in the gas response could be observed from sensors with enhanced morphologies compared to control sensors grown without application of an electric field. - Highlights: • Electric field assisted chemical vapour deposition method • Ability to create high surface area film architectures • Can produce enhanced sensor response • Good control over film properties.

  2. Electric field modelling for point-plane gap

    International Nuclear Information System (INIS)

    The electric field distribution for point-plane gap is modelled both for stressed point and stressed plane electrodes. In simulations, the influence of the discharge chamber walls is taken into account. The size of an avalanche and the corresponding current pulse are calculated. The results are compared with those got other field distribution approximations. (author)

  3. Analysis of the temporal electric fields in lossy dielectric media

    DEFF Research Database (Denmark)

    McAllister, Iain Wilson; Crichton, George C

    1991-01-01

    The time-dependent electric fields associated with lossy dielectric media are examined. The analysis illustrates that, with respect to the basic time constant, these lossy media can take a considerable time to attain a steady-state condition. Time-dependent field enhancement factors are considered...

  4. Numerical simulation of electromagnetic and flow fields of TiAI melt under electric field

    Institute of Scientific and Technical Information of China (English)

    Zhang Yong; Ding Hongsheng; Jiang Sanyong; Chen Ruirun; Guo Jingjie

    2010-01-01

    This article aims at building an electromagnetic and fluid model, based on the Maxwell equations and Navier-Stokes equations, in TiAI melt under two electric fields. FEM (Finite Element Method) and APDL (ANSYS Parametric Design Language) were employed to perform the simulation, model setup, loading and problem solving. The melt in molds of same cross section area with different flakiness ratio (i.e. width/depth) under the load of sinusoidal current or pulse current was analyzed to obtain the distribution of electromagnetic field and flow field. The results show that the induced magnetic field occupies sufficiently the domain of the melt in the mold with a flakiness ratio of 5:1. The melt is driven bipolarly from the center in each electric field. It is also found that the pulse electric field actuates the TiAI melt to flow stronger than what the sinusoidal electric field does.

  5. Time Evolution of Electric Fields in CDMS Detectors

    CERN Document Server

    Leman, S W; Brink, P L; Cabrera, B; Chagani, H; Cherry, M; Cushman, P; Silva, E Do Couto E; Doughty, T; Figueroa-Feliciano, E; Mandic, V; McCarthy, K A; Mirabolfathi, N; Pyle, M; Reisetter, A; Resch, R; Sadoulet, B; Serfass, B; Sundqvist, K M; Tomada, A; Young, B A; Zhang, J

    2011-01-01

    The Cryogenic Dark Matter Search (CDMS) utilizes large mass, 3" diameter x 1" thick target masses as particle detectors. The target is instrumented with both phonon and ionization sensors, the later providing a $\\sim$1 V cm$^{-1}$ electric field in the detector bulk. Cumulative radiation exposure which creates $\\sim 200\\times 10^6$ electron-hole pairs is sufficient to produce a comparable reverse field in the detector thereby degrading the ionization channel performance. To study this, the existing CDMS detector Monte Carlo has been modified to allow for an event by event evolution of the bulk electric field, in three spatial dimensions. Our most resent results and interpretation are discussed.

  6. Premixed combustion under electric field in a constant volume chamber

    KAUST Repository

    Cha, Min Suk

    2012-12-01

    The effects of electric fields on outwardly propagating premixed flames in a constant volume chamber were experimentally investigated. An electric plug, subjected to high electrical voltages, was used to generate electric fields inside the chamber. To minimize directional ionic wind effects, alternating current with frequency of 1 kHz was employed. Lean and rich fuel/air mixtures for both methane and propane were tested to investigate various preferential diffusion conditions. As a result, electrically induced instability showing cracked structure on the flame surface could be observed. This cracked structure enhanced flame propagation speed for the initial period of combustion and led to reduction in flame initiation and overall combustion duration times. However, by analyzing pressure data, it was found that overall burning rates are not much affected from the electric field for the pressurized combustion period. The reduction of overall combustion time is less sensitive to equivalence ratio for methane/air mixtures, whereas the results demonstrate pronounced effects on a lean mixture for propane. The improvement of combustion characteristics in lean mixtures will be beneficial to the design of lean burn engines. Two hypothetical mechanisms to explain the electrically induced instability were proposed: 1) ionic wind initiated hydrodynamic instability and 2) thermodiffusive instability through the modification of transport property such as mass diffusivity. © 2012 IEEE.

  7. PIC simulation of electrodeless plasma thruster with rotating electric field

    Energy Technology Data Exchange (ETDEWEB)

    Nomura, Ryosuke; Ohnishi, Naofumi; Nishida, Hiroyuki [Department of Aerospace Engineering, Tohoku University, Sendai 980-8579 (Japan); Department of Mechanical Systems Engineering, Tokyo University of Agriculture and Technology, Tokyo 184-8588 (Japan)

    2012-11-27

    For longer lifetime of electric propulsion system, an electrodeless plasma thruster with rotating electric field have been proposed utilizing a helicon plasma source. The rotating electric field may produce so-called Lissajous acceleration of helicon plasma in the presence of diverging magnetic field through a complicated mechanism originating from many parameters. Two-dimensional simulations of the Lissajous acceleration were conducted by a code based on Particle-In-Cell (PIC) method and Monte Carlo Collision (MCC) method for understanding plasma motion in acceleration area and for finding the optimal condition. Obtained results show that azimuthal current depends on ratio of electron drift radius to plasma region length, AC frequency, and axial magnetic field. When ratio of cyclotron frequency to the AC frequency is higher than unity, reduction of the azimuthal current by collision effect is little or nothing.

  8. The role of electric fields in the cometary environment

    International Nuclear Information System (INIS)

    Polarization electric fields in the cometary environment are shown to influence both the cometary plasma and the fine cometary dust. The role of the ambipolar electric field on the dynamics and thermodymamics of the cometary ionosphere is discussed. It is shown that this field decelerates and cools the plasma in the outer cometary ionosphere, and shock waves can develop in the plasma flow due to this deceleration. The consequences of electrostatic change of the cometary dust are considered. It is shown that while the consequences are minimal within the cometary ionosphere, they are substantial outside. The convectional electric field in the inflowing solar wind (both outside and inside the outer shock), as well as the Coulomb drag of this plasma on the charged dust, affect significantly the dynamics of the lower end of the dust mass spectrum. (author)

  9. Combining fluidized activated carbon with weak alternating electric fields for disinfection

    NARCIS (Netherlands)

    Racyte, J.; Sharabati, J.; Paulitsch-Fuchs, A.H.; Yntema, D.R.; Mayer, M.J.J.; Bruning, H.; Rijnaarts, H.H.M.

    2011-01-01

    This study presents fluidized bed electrodes as a new device for disinfection. In the fluidized bed electrodes system, granular activated carbon particles were suspended, and an alternating radio frequency electric field was applied over the suspended bed. Proof-of-principle studies with the lumines

  10. Electric-field gradients used to measure atomic short range order: as a case-study

    Science.gov (United States)

    Cottenier, S.; Meersschaut, J.; Vermeire, L.; Demuynck, S.; Swinnen, B.; Rots, M.

    1999-02-01

    A scheme is presented in order to obtain complete information on atomic short range order in crystalline materials based on measuring the electric-field gradient on a probe nucleus. Limitations and possible improvements of the method are discussed. When applied to U(In0.5Sn0.5)3, short range order with In-Sn attraction is found.

  11. The use of an electric field for the removal of alum from treated wooden objects

    DEFF Research Database (Denmark)

    Christensen, Iben Vernegren; Ottosen, Lisbeth M.; Jensen, Poul;

    2009-01-01

    In this paper the removal of sulfate and aluminum ions from waterlogged alum treated wood with the use of an applied electric field is in focus. Removal of alum is seen as the first step towards re-conservation of the wood with e.g. PEG. Alum treated wood samples from the Hjortspring finds (app....... 350 BC) was used in this investigation and a total of six experiments are presented here. An electric DC field was applied across the wood for 4-20 days. A constant current of 1-5 mA was applied and the corresponding voltage drop initially low, often below 10 V. At the end of the experiments sulfate...... has moved as expected towards the positively charged electrode (anode) and after 20 days only 10% of the sulfate was left in the wood. The majority of the sulfate was removed with the use of the electric field. It was shown that it is possible to apply the electric field and remove sulfate in both...

  12. THE ONSET OF ELECTRICAL BREAKDOWN IN DUST LAYERS: II. EFFECTIVE DIELECTRIC CONSTANT AND LOCAL FIELD ENHANCEMENT

    Science.gov (United States)

    Part 1 of the work has shown that electrical breakdown in dust layers obeys Paschen's Law, but occurs at applied field values which appear too small to initiate the breakdown. In this paper the authors show how an effective dielectric constant characterizing the dust layer can be...

  13. Momentum transfer theory of non-conservative charged particle transport in crossed electric and magnetic fields

    International Nuclear Information System (INIS)

    Momentum - transfer approximation is applied to momentum and energy balance equations describing reacting particle swarms in gases in crossed electric and magnetic fields. Transport coefficients of charged particles undergoing both inelastic and reactive, non-particle-conserving collisions with a gas of neutral molecules are calculated. Momentum - transfer theory (MTT) has been developed mainly by Robson and collaborators. It has been applied to a single reactive gas and mixtures of reactive gases in electric field only. MTT has also been applied in crossed electric and magnetic fields recently and independently of our work but the reactive collisions were not considered. Consider a swarm of electrons of charge e and mass m moving with velocity rvec v through a neutral gas under the influence of an applied electric rvec E and magnetic rvec B field. The collision processes which we shall investigate are limited to elastic, inelastic and reactive collisions of electrons with gas molecules. Here we interpret reactive collisions as collisions which produce change in number of the swarm particles. Reactive collisions involve creation (ionization by electron impact) or loss (electron attachment) of swarm particles. We consider only single ionization in approximation of the mass ratio m/m00 are masses of electrons and neutral particles, respectively. We assume that the stage of evolution of the swarm is the hydrodynamic limit (HDL). In HDL, the space - time dependence of all properties is carried by the number density n of swarm particles

  14. Relationship between ionospheric electric fields and magnetic activity indices

    Science.gov (United States)

    Shirapov, D. Sh.

    2012-02-01

    The relations between electric fields in the daytime and nighttime sectors of the polar ionosphere and magnetic activity indices of auroral region (AL) and northern polar cap (PCN) are studied. It is found that the above relations do exist and are described by: a) equations U {pc/(1)} (kV) = 27.62 + 21.43PCN with a correlation coefficient R = 0.87 and U {pc/(1)} (kV) = 4.06 + 49.21PCN - 6.24 PCN2 between the difference in the electric potentials across the polar cap in the daytime sector U {pc/(1)} and PCN and b) regression equation U {pc/(2)} (kV) = 23.33 + 0.08|AL| with R = 0.86 between the difference in the electric potentials across the polar cap in the nighttime sector U {pc/(2)} and |AL|. It is shown that: a) it is possible to use the AL and PCN indices for real-time diagnostics of instantaneous values of the electric fields in the daytime and nighttime sectors of the polar ionosphere in the process of a substorm development; b) at the expansion phase of a substorm, due to calibration of PCN values by the values of the solar wind electric field E sw, the PCN index does not feel the contribution of the western electrojet and, accordingly, the contribution of the nighttime ionospheric electric field U {pc/(2)}, governed by the reconnection in the magnetospheric tail.

  15. Manipulation of red blood cells with electric field

    Science.gov (United States)

    Saboonchi, Hossain; Esmaeeli, Asghar

    2009-11-01

    Manipulation of bioparticles and macromolecules is the central task in many biological and biotechnological processes. The current methods for physical manipulation takes advantage of different forces such as acoustic, centrifugal, magnetic, electromagnetic, and electric forces, as well as using optical tweezers or filtration. Among all these methods, however, the electrical forces are particularly attractive because of their favorable scale up with the system size which makes them well-suited for miniaturization. Currently the electric field is used for transportation, poration, fusion, rotation, and separation of biological cells. The aim of the current research is to gain fundamental understanding of the effect of electric field on the human red blood cells (RBCs) using direct numerical simulation. A front tracking/finite difference technique is used to solve the fluid flow and electric field equations, where the fluid in the cell and the blood (plasma) is modeled as Newtonian and incompressible, and the interface separating the two is treated as an elastic membrane. The behavior of RBCs is investigated as a function of the controlling parameters of the problem such as the strength of the electric field.

  16. Charge Inversion Effects in Electrophoresis of Polyelectrolytes in the Presence of Multivalent Counterions and Transversal Electric Fields

    Directory of Open Access Journals (Sweden)

    Sorin Nedelcu

    2014-12-01

    Full Text Available By molecular dynamics simulations we investigate the transport of charged polymers in confinement, under externally applied electric fields, in straight cylinders of uniform diameter and in the presence of monovalent or multivalent counterions. The applied electric field has two components; a longitudinal component along the axis of the cylinder and a transversal component perpendicular to the cylinder axis. The direction of electrophoretic velocity depends on the polyelectrolyte length, valency of the counterions present in solution and transversal electric field value. A statistical model is put forward in order to explain these observations.

  17. Water-methanol separation with carbon nanotubes and electric fields

    Science.gov (United States)

    Winarto, Affa; Takaiwa, Daisuke; Yamamoto, Eiji; Yasuoka, Kenji

    2015-07-01

    Methanol is used in various applications, such as fuel for transportation vehicles, fuel cells, and in chemical industrial processes. Conventionally, separation of methanol from aqueous solution is by distillation. However, this method consumes a large amount of energy; hence development of a new method is needed. In this work, molecular dynamics simulations are performed to investigate the effect of an electric field on water-methanol separation by carbon nanotubes (CNTs) with diameters of 0.81 to 4.07 nm. Without an electric field, methanol molecules fill the CNTs in preference to water molecules. The preference of methanol to occupy the CNTs over water results in a separation effect. This separation effect is strong for small CNT diameters and significantly decreases with increasing diameter. In contrast, under an electric field, water molecules strongly prefer to occupy the CNTs over methanol molecules, resulting in a separation effect for water. More interestingly, the separation effect for water does not decrease with increasing CNT diameter. Formation of water structures in CNTs induced by an electric field has an important role in the separation of water from methanol.Methanol is used in various applications, such as fuel for transportation vehicles, fuel cells, and in chemical industrial processes. Conventionally, separation of methanol from aqueous solution is by distillation. However, this method consumes a large amount of energy; hence development of a new method is needed. In this work, molecular dynamics simulations are performed to investigate the effect of an electric field on water-methanol separation by carbon nanotubes (CNTs) with diameters of 0.81 to 4.07 nm. Without an electric field, methanol molecules fill the CNTs in preference to water molecules. The preference of methanol to occupy the CNTs over water results in a separation effect. This separation effect is strong for small CNT diameters and significantly decreases with increasing

  18. Electric field and infrared radiation in the troposphere before earthquakes

    Directory of Open Access Journals (Sweden)

    V. A. Liperovsky

    2011-12-01

    Full Text Available Some years ago, a model of the generation of local electric fields in the atmosphere a few days before earthquakes and up to a few days after the seismic shock was proposed. In the model, the generation of the electric fields occurs because of an increased ionisation intensity of the atmosphere in the presence of aerosols. The generation of the electric field is the result of the fact that the larger aerosols, which are mainly negatively charged, have a larger velocity of gravitational precipitation than the smaller, which are mainly positively charged aerosols. The ionisation in such atmospheric regions is caused by radon, the concentration of which increases in earthquake preparation regions. The formation of mosaic-likely distributed areas of electric fields with intensities of 3 × 102 – 105 Vm−1 and, on the other hand, large areas with increased electrical conductivity cause a series of physical effects, e.g. the occurrence of infrared emissions with a specific spectrum, which may be studied using earth-based, atmospheric and satellite observations. In the present paper, the model of the generation of local electric fields is further developed, improving the description of the force balance on the aerosols in the atmosphere. A recently proposed laboratory experiment is briefly discussed, which is carried out to prove the theoretically predicted intensification of infrared emissions some hours-days before earthquakes. Besides the experiment described, it will be operated on Kamchatka in the near future to scan mosaic-likely distributed regions of electric fields in the atmosphere during earthquake preparation times.

  19. Signal amelioration of electrophoretically deposited whole-cell biosensors using external electric fields

    Energy Technology Data Exchange (ETDEWEB)

    Ben-Yoav, Hadar, E-mail: benyoav@post.tau.ac.il [Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, Tel-Aviv 69978 (Israel); Amzel, Tal [Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, Tel-Aviv 69978 (Israel); Sternheim, Marek [Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel-Aviv, 69978 (Israel); Belkin, Shimshon [Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem, 91904 (Israel); Rubin, Adi [Department of Molecular Microbiology and Biotechnology, Faculty of Life Sciences, Tel Aviv University, Tel-Aviv, 69978 (Israel); Shacham-Diamand, Yosi [Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, Tel-Aviv 69978 (Israel); Freeman, Amihay [Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel-Aviv, 69978 (Israel)

    2011-11-01

    Highlights: > We present an electrochemical whole-cell biochip that can apply electric fields. > We examine the integration of cells on a biochip using electrophoretic deposition. > The effect of electric fields on the whole-cell biosensor has been demonstrated. > Relatively short DC electric pulse improves the performance of whole-cell biosensors. > Prolonged AC electric fields deteriorated the whole-cell biosensor performance. - Abstract: This paper presents an integrated whole-cell biochip system where functioning cells are deposited on the solid micro-machined surfaces while specially designed indium tin oxide electrodes that can be used to apply controllable electric fields during various stages; for example during cell deposition. The electrodes can be used also for sensing currents associated with the sensing mechanisms of electrochemical whole-cell biosensors. In this work a new approach integrating live bacterial cells on a biochip using electrophoretic deposition is presented. The biomaterial deposition technique was characterized under various driving potentials and chamber configurations. An analytical model of the electrophoretic deposition kinetics was developed and presented here. The deposited biomass included genetically engineered bacterial cells that may respond to toxic material exposure by expressing proteins that react with specific analytes generating electrochemically active byproducts. In this study the effect of external electric fields on the whole-cell biochips has been successfully developed and tested. The research hypothesis was that by applying electric fields on bacterial whole-cells, their permeability to the penetration of external analytes can be increased. This effect was tested and the results are shown here. The effect of prolonged and short external electric fields on the bioelectrochemical signal generated by sessile bacterial whole-cells in response to the presence of toxins was studied. It was demonstrated that relatively

  20. Signal amelioration of electrophoretically deposited whole-cell biosensors using external electric fields

    International Nuclear Information System (INIS)

    Highlights: → We present an electrochemical whole-cell biochip that can apply electric fields. → We examine the integration of cells on a biochip using electrophoretic deposition. → The effect of electric fields on the whole-cell biosensor has been demonstrated. → Relatively short DC electric pulse improves the performance of whole-cell biosensors. → Prolonged AC electric fields deteriorated the whole-cell biosensor performance. - Abstract: This paper presents an integrated whole-cell biochip system where functioning cells are deposited on the solid micro-machined surfaces while specially designed indium tin oxide electrodes that can be used to apply controllable electric fields during various stages; for example during cell deposition. The electrodes can be used also for sensing currents associated with the sensing mechanisms of electrochemical whole-cell biosensors. In this work a new approach integrating live bacterial cells on a biochip using electrophoretic deposition is presented. The biomaterial deposition technique was characterized under various driving potentials and chamber configurations. An analytical model of the electrophoretic deposition kinetics was developed and presented here. The deposited biomass included genetically engineered bacterial cells that may respond to toxic material exposure by expressing proteins that react with specific analytes generating electrochemically active byproducts. In this study the effect of external electric fields on the whole-cell biochips has been successfully developed and tested. The research hypothesis was that by applying electric fields on bacterial whole-cells, their permeability to the penetration of external analytes can be increased. This effect was tested and the results are shown here. The effect of prolonged and short external electric fields on the bioelectrochemical signal generated by sessile bacterial whole-cells in response to the presence of toxins was studied. It was demonstrated that