Electric Field Characteristics Research Articles

Effect of trivalent transition metal ion substitution in multifunctional properties of Dy2O3 system

The present work describes the systematic study on inducing multiferroic properties in non-magnetic Dy2O3 system. The ceramic compounds of Dy2−xFexO3 (where x = 0.1–1.5) have been prepared by solid state reaction method. The powder X-ray diffraction patterns of all the prepared compounds reveal the strong influence of transition metal ion (Fe) in the Dy2O3 crystal structure. By Rietveld analysis, it is determined that with respect to increasing concentration of Fe3+ ion at Dy3+ site leads to transformation of crystal structure from Cubic to Orthorhombic with varying concentration of DyFeO3 phase and further increase in Fe3+ concentration leads to the formation of Garnet phase in Dy2−xFexO3 compounds. The scanning electron microscopic images of the samples confirm the change in surface morphology with increasing grain boundaries and porosity due to the substitution of Fe in Dy2O3 system which may effects on the electrical transport properties of the materials and increasing concentration of Fe in Dy2O3 system is also analyzed by energy dispersive analysis spectra. By Raman spectral analysis, it is identified that the strong absorption band of Cubic Dy2O3 compound at 373 cm−1 is gradually shifted to 257 cm−1 which indicates the molecular stretching motion of RE–O bond in REO6 octahedra and the large deviation in position of intense Raman bands below 300 cm−1 confirms the incorporation of Fe3+ ion in the host Dy2O3 lattice and imparting large polarizability in the prepared compounds due to translational motions of ReO6 octahedrons by variation in bond length and reduced mass of the bonding atoms. Diffused reflectance spectroscopy analysis implies the semiconducting nature of all the prepared compounds. It is also identified that the energy gap values goes on decreasing till DyFeO3 and then starts increasing due to change in crystal structure by cubic to orthorhombic and then orthorhombic to garnet phase. From the magnetization studies, it is found that till even substitution of Fe (i.e. x = 0.1–0.9) in Dy2−xFexO3 system, the compounds exhibits paramagnetic nature whereas from x = 1.0 i.e. DyFeO3, the samples exhibits ferromagnetic nature. The variation of magnetization behaviour from paramagnetic to ferromagnetic in higher concentration of Fe explicit the feasibility of attaining ferroic behaviour in Garnet mixed phase ceramic compounds. The electric polarization analysis reveal that while substituting Fe3+ ion in Dy3+ site by more than 50% of molecular ratio, the compounds exhibits non-zero remanance and coercivity values with respect to applied d.c. electric field and evident peculiar ferroelectric characteristic of those compounds. The maximum saturation polarization achieved in Dy0.6Fe1.4O3 compound is 0.2 µC/cm2 and found comparable with the results observed from Bismuth Ferrite related compounds.

Electrical Guidance Efficiency of Downstream‐Migrating Juvenile Sea Lampreys Decreases with Increasing Water Velocity

AbstractWe tested the efficacy of a vertically oriented field of pulsed direct current (VEPDC) created by an array of vertical electrodes for guiding downstream‐moving juvenile Sea Lampreys Petromyzon marinus to a bypass channel in an artificial flume at water velocities of 10–50 cm/s. Sea Lampreys were more likely to be captured in the bypass channel than in other sections of the flume regardless of electric field status (on or off) or water velocity. Additionally, Sea Lampreys were more likely to be captured in the bypass channel when the VEPDC was active; however, an interaction between the effects of VEPDC and water velocity was observed, as the likelihood of capture decreased with increases in water velocity. The distribution of Sea Lampreys shifted from right to left across the width of the flume toward the bypass channel when the VEPDC was active at water velocities less than 25 cm/s. The VEPDC appeared to have no effect on Sea Lamprey distribution in the flume at water velocities greater than 25 cm/s. We also conducted separate tests to determine the threshold at which Sea Lampreys would become paralyzed. Individuals were paralyzed at a mean power density of 37.0 µW/cm3. Future research should investigate the ability of juvenile Sea Lampreys to detect electric fields and their specific behavioral responses to electric field characteristics so as to optimize the use of this technology as a nonphysical guidance tool across variable water velocities.Received April 26, 2016; accepted November 1, 2016 Published online February 13, 2017

Characteristics of low altitude ionospheric electric field over Hainan Island, China

A sounding rocket experiment undertaken by the Chinese Meridian Project from a low latitude station on Hainan Island (19.5°N, 109.1°E), China, measured the DC electric field during 05:45–05:52 LT on April 5, 2013. The data observed using a set of electric field double probes, as part of the rocket’s scientific payload, revealed the special profile of how the vectors of the DC electric field vary with altitude between 130 and 190 km. During the experiment, the vertical electric field was downward, and the maximum vertical electric field was nearly 5.1 mV/m near the altitude of 176 km. The zonal electric field was eastward and slightly less than 0.6 mV/m. The plasma drift velocity was estimated from the E × B motion, and the zonal drift velocity was eastward and of the order of 100 m/s. The zonal wind velocity was also estimated using the drift velocity near the maximum density height in the F1-region, and it was found to be nearly 120 m/s. This work constituted the first in situ measurement of the DC electric field conducted within the F1-region (between 130 and 190 km) in the East Asian Sector.

Study on dielectric, optic and magnetic properties of manganese and nickel co-doped bismuth ferrite thin film

BiFeO3 (BFO), Mn (7.5%)-doped BFO (BFMO), Ni (7.5%)-doped BFO (BFNO), as well as Mn (3.75%) and Ni (3.75%) co-doped BFO (BFMNO) films were deposited on indium tin oxide (ITO)/glass substrates by sol–gel process. X-ray diffraction (XRD) analysis indicated that the BFO and BFNO presented single rhombohedral structure, while BFMO and BFMNO thin films presented tetragonal structure. The current density versus electric field (J–E) characteristics indicated that leakage conduction can be decreased with Mn and/or Ni doped. The films conduction mechanism of BFO and BFNO are space-charge-limited current in the high electric field region, while for BFMO and BFMNO is Ohmic’s conduction in all electric field region. The optical band gap of the BFO, BFMO, BFNO and BFMNO thin films are 2.18, 2.22, 2.3 and 2.32 eV, respectively. The inhomogeneous spin-modulated magnetic structure of BiFeO3 was modified by Mn and/or Ni substitution.

Analysis of electric field and emission spectrum in the glow discharge of therapeutic plasma electrode

ABSTRACTGas-filled glass plasma electrodes coupled with high-frequency high-voltage generators are used in medicine and dentistry for more than a century. In recent literature, therapeutic effects of such procedure have been explained through topical bio-oxidative effects of ozone generated by the dielectric barrier discharge. The aim of this study was to evaluate characteristics of electric field and optical emission spectrum generated in the treatment field by the glow discharge of the plasma electrode. Emission spectrum in red and near-infrared wavelength range (540–886 nm) and pulsed electric field (impulse frequency 1053 Hz, exponentially damped sine wave in the range of 33 kHz, duty cycle 20%) were recorded. Estimated electric field strength at 1-mm distance was in the range from 5.8 to 13.7 kV/m and between 106 and 108 V/m in the close proximity of electrode's surface (below 0.01 mm). Recorded factors are integral constituents in the treatment field and their properties can be correlated to the known biological and therapeutic effects of photostimulation and electrostimulation. These factors present important bioactive components which could be responsible for therapeutic effects, reported in number of clinical studies, especially those which could not be explained through topical bio-oxidative effects of ozone.

Electromagnetic Shielding Analysis of Multiple Slits on a Metal Plate Coated With a Ferrite Sheet

This paper presents a rigorous analysis of electromagnetic (EM) field penetration into multiple slits on a metal plate loaded with a ferrite sheet having frequency-dependent complex permeability. The Fourier transform is used to represent the EM fields in the spectral domain, and the mode-matching technique is enforced to obtain a solution in rapidly converging series form, leading to numerically efficient results. Electric and magnetic shielding characteristics in near-field region are investigated over wideband frequency range in terms of the presence or absence of a ferrite sheet with frequency-dependent magnetic permeability. It is observed that the shielding characteristics of electric and magnetic fields are different from each other at the low-frequency range in the near-field region. The number of slits and the ferrite sheet have significant influence on the magnetic shielding performance. In addition, the effect of nonperiodic multiple slits on the shielding effectiveness is examined. The proposed method is verified by comparing the results with those of a commercial EM solver, and good agreement is achieved using the feature selective validation.

Effects of disturbed electric fields in the low‐latitude and equatorial ionosphere during the 2015 St. Patrick's Day storm

AbstractThe 2015 St. Patrick's Day geomagnetic storm with SYM‐H value of −233 nT is an extreme space weather event in the current 24th solar cycle. In this work, we investigated the main mechanisms of the profound ionospheric disturbances over equatorial and low latitudes in the Asian‐Australian sector and the American sector during this super storm event. The results reveal that the disturbed electric fields, which comprise penetration electric fields (PEFs) and disturbance dynamo electric fields (DDEFs), play a decisive role in the ionospheric storm effects in low latitude and equatorial regions. PEFs occur on 17 March in both the American sector and the Asian‐Australian sector. The effects of DDEFs are also remarkable in the two longitudinal sectors. Both the DDEFs and PEFs show the notable local time dependence, which causes the sector differences in the characteristics of the disturbed electric fields. This differences would further lead to the sector differences in the low‐latitude ionospheric response during this storm. The negative storm effects caused by the long‐duration DDEFs are intense over the Asian‐Australian sector, while the repeated elevations of hmF2 and the equatorial ionization anomaly intensifications caused by the multiple strong PEFs are more distinctive over the American sector. Especially, the storm time F3 layer features are caught on 17 March in the American equatorial region, proving the effects of the multiple strong eastward PEFs.

English

Electrostatic oiler are made as the research object, the multiple field spray characteristics of air flow field, electric field and discrete fog field in the process of spraying were analyzed. The influence of electrostatic spray deposition characteristics has been studied by changing the electrostatic voltage and electrode gap. The experiment about electrostatic oil spray has been verified. The results show that droplets of axial velocity are larger in the outlet of spray field near the larger intensity area. Near the metal plate, the air flow accelerates the droplets and makes the fog area diffused. Due to the droplets deposition and diffusion on the metal plate, the air is around in motion. With the electrostatic voltage increases, the droplet size decreases to a certain value then basically unchanged and afterwards the droplet size increases as the electrodes distance increases. The droplet deposition area increases first and then decreases with the increase in voltage, and then decreases with the increasing in electrodes distance; the density fluctuation of the droplet deposition is uniform and the deposition amount is moderate. When the voltage reaches 50 to 60 kV and the electrode spacing reaches 195 to 225 mm, the electrostatic spray atomization effect is better. Key words: Electrostatic spraying, electrostatic oiler, multi-field characteristics, droplet deposition distribution, spraying experiment.

Schottky–Richardson, Poole–Frenkel, and Space Charge Limited Current Mechanisms in M‐Type Sr(MnTi)xFe(12‐2x)O19 Ferrite

The Static Current Density–Electric Field characteristics of Sr(MnTi)xFe(12‐2x)O19 ferrite compositions (x = 0.5, 1.0, 1.5, and 2.0) have been investigated from 4.15 to 36.30 kV/m at room temperature. Ohmic and nonohmic regions are observed at low and high field regimes. The various models, governing nonlinear conduction, are discussed qualitatively in terms of Space charge limited current (SCLC), Ionic hopping, Poole–Frenkel, Schottky–Richardson, and Fowler–Nordheim mechanisms. The results depict Child‐Langmuir type SCLC in the investigated compositions.

Investigation of microwave absorption and DC electrical properties of Mn2+ and Ti4+ substituted SrMnxTixFe(12−2x)O19 ferrite

The microwave characterization of Mn2+ and Ti4+ ions substituted M-type SrMnxTixFe(12−2x)O19 hexagonal ferrite (x = 0.5, 1.0, 1.5 and 2.0) has been reported as a function of frequency, substitution and thickness in X-band. The static current density (J)-electric field (E) characteristics have been investigated as a function of substitution at an applied field from 4 kV/m to 40 kV/m. The microwave characteristics have been measured using microwave power meter in the rectangular slotted waveguide and the current density has been measured using electrometer. The microwave absorption has been evaluated using the standard model of quarter wavelength criterion. The microwave absorption is enhanced while electrical current density is decreased with the substitution of Mn2+ and Ti4+ ions. The different compositions have scope for microwave or high frequency absorber applications.

New Experimental Investigation of Magnetic and Electric Fields in the Vicinity of High-Voltage Power Lines

In this paper, the theoretical and experimental characteristics of magnetic and electric fields in the vicinity of high voltage lines are investigated. To realize these measurements and calculations, we have developed some equations for two overhead power line configurations of 150 kV (single circuit, double circuit), based on Biot-savart law, image and Maxwell theories, in order to calculate the magnetic and electric fields. The measurements were done to a maximum distance from the tower of 50 m, at a height of 1m from the ground. These experiments take into consideration the real situations of the power lines and associated equipment. The experimental results obtained are near to that of the Biot-Savart theoretical results for a far distance from the tower; and for a distance close to the power line, the results from the image theory are in good agreement with the experimental results.

Characteristics of the horizontal electric field associated with nearby lightning return strokes

There exists inherent difficulty in measuring the horizontal electric field (Er) associated with lightning return strokes due to the overshadowing effect of the vertical electric field component, not much progress in Er measurements were observed until now. In order to study the characteristics of Er associated with nearby lightning return strokes, the modified transmission-line model with linear current decay with height (MTLL) return stroke model and Finite Difference Time Domain (FDTD) method were used to calculate Er for 12 observation points with different distances (20, 50 100, and 200m) away from the lightning channel and different heights (0, 10, and 20m) above ground. Four characteristic parameters, namely, the return-stroke speed (v), the total length of the return stroke channel (H), the ground relative permittivity (ε) and the ground conductivity (σ), were considered. Results show that the polarity of Er changes between the ground level and the space. The influence intensity rank of the four characteristic parameters on Er at ground level is: σ>v>ε>H. The influence of the characteristic parameters on Er are more important for v≤0.6c, H≤6000m and σ≤2.5×10−3S/m.

Microstructure, leakage current and dielectric tunability of Na0.5Bi0.5(Ti0.99Zn0.01)O3 thin films: An annealing atmosphere-dependent study

Na0.5Bi0.5(Ti0.99Zn0.01)O3 (NBTZn) thin films were deposited on the indium tin oxide (ITO)/glass substrates annealed under different atmospheres (air, N2, O2, O2/N2) via a metal organic decomposition process. The effects of annealing atmosphere on crystallization and electrical properties were mainly investigated. All the thin films exhibit single perovskite structures with predominant (110) orientation. Large grains are observed in N2 due to the high content of oxygen vacancy. For the film annealed in O2/N2 atmosphere, the lower leakage current density and higher dielectric tunability can be obtained, which may be ascribed to the improvement of crystallization with more homogeneous grain sizes and dense microstructure. Also, the effects of measuring frequency on dielectric constant–electric field characteristic are discussed. A higher tunability of 47.6% and figure of merit of 7.9 at 300kV/cm and 100kHz for NBTZn film can be observed.

Study on stability of electric field in multimode microwave heating cavity

Microwave heating has been widely used and the heating uniformity is related to the characteristics of electric field. In this paper, we investigate the stability of electric field in a multimode microwave cavity by analyzing the spectrum and the condition number of integral equation. Results show that the stability of the electric field is mainly dependent on microwave frequency, the permittivity of heating object and cavity geometrical parameters. Particularly, when the heating object has a low loss factor, the electric field is generally unstable. Namely, a tiny shift of the parameters mentioned above will result in dramatic changes of electric field distribution. Besides, the instability of the electric field increases with the lower loss, the higher microwave frequency or the larger permittivity of the heating object.

Characteristics of the atmospheric electric field and correlation with CO2 at a rural site in southern Balkans

In the current work, 4 years of atmospheric electric field observations at a rural site near Xanthi, Greece, are presented for 2011–2014. The site is situated in an area with very high radon fluxes and high thunderstorm activity. The annual variation is consistent with that at other Northern Hemisphere continental stations, with maxima (minima) occurring during the cold (warm) months. The diurnal variation of the atmospheric electric field both for fair weather (FW) and all weather is found to exhibit a double-peak structure corresponding to local effects and global thunderstorm activity. Comparison with the Carnegie curve shows that nighttime hours and winter months are preferable for observing the Global Electric Circuit at the Xanthi site. Finally, it is shown that atmospheric CO2 measurements can be effectively utilized as a stratification proxy, indicating conditions of potential radon trapping, whereas CO2 was found to anticorrelate with the atmospheric electric field during such conditions.

Charge transport behaviors in epitaxial BiFeO3 thick films sputtered with different Ar/O2 flow ratios

Heteroepitaxial BiFeO3 thick films were prepared on (100) LaAlO3 substrates using magnetron sputtering. The sputtering atmosphere, i.e. Ar/O2 flow ratio, showed significant influence on the charge transport behaviors of BiFeO3 films. The distinct current density–electric field (J–E) characteristics of films were fitted to three charge transport models: ionic conduction, Schottky emission, and space-charge-limited-current (SCLC). These models were verified by an Auger depth profiling study, which revealed the chemical compositions of the films across their thicknesses. The apparent flow ratio dependence of charge transport in these films is well explained by the models with the supporting Auger data.

Nonlinear plasma resonance in inhomogeneous relativistic plasma

We present a theoretical study of relativistic electron plasma oscillations in the plasma resonance region based on the renormalization group symmetry method. A steady-state solution to equations describing the electron dynamics in the vicinity of the plasma resonance is found and spatial-temporal and spectral characteristics of the potential electric field are discussed.

３次元圧電接合体の電場に及ぼす界面端における特異場の影響とその応用

Singular electric displacement fields occur around the vertex of interface in a piezoelectric material joints under loadings. In the previous study, influence of load conditions on singular electric displacement fields in the piezoelectric material joints were investigated to apply for engineering. In this study, some characteristics of singular electric displacement fields in an outside domain of piezoelectric material joints were investigated by using 3-dimensional finite element analysis. Influences of loading conditions on singular electric displacement fields are discussed . Singular electric displacement fields in an outside domain of piezoelectric material joints occur around the vertex of interface in it under loadings. Singular electric displacement fields are infulenced by tme change of the stress to depend on a piezoelectric material joints.

NEAR-GROUND TRANSIENT FIELD OF A HIGH-ALTITUDE ELECTROMAGNETIC PULSE (HEMP) CONSIDERING NONLINEAR AIR CONDUCTIVITY AND GROUND REFLECTION

Transient field of a high-altitude electromagnetic pulse (HEMP) induced near ground is simulated, of which the ground reflection can not be neglected. The Jefimenko's equation is applied to compute the incident electric field near the ground, attributed to both the primary and the secondary currents in the source region. The field-dependent air conductivity in the source region is obtained by solving three nonlinear governing equations iteratively, and the reflected field is computed in the frequency domain. The γ rays generated by a high-altitude nuclear explosion strike air molecules in the upper atmosphere, producing Compton electrons which move almost in parallel to the γ rays and constitute a primary current (1, 2). The Compton electrons also ionize air molecules, creating secondary electrons which in turns modify the effective conductivity of the atmosphere (2, 3). The electromagnetic field radiated by the primary current, under the influence of the air conductivity, is conventionally called a high-altitude electromagnetic pulse (HEMP). The Lienard-Wiechert potentials were used to compute HEMPs radiated by the primary current (4), where only the synchrotron radiation was considered, while the radiation attributed to frictional losses (Bremsstrahlung radiation) was neglected. In (5), HEMP was computed by using the Jefimenko's equation as well as the CHAP's code (3). The characteristics of electric fields attributed to primary and secondary currents were also discussed. In (6), the electric field of early-time HEMP was simulated with different heights of burst (HOBs), explosive yields and observation locations. The effective conductivity in the source region is nonlinearly related to the in situ electric field, which can significantly affect the accuracy of simulated HEMP waveform near ground. In this work, we propose an iterative method to compute both the electric field and the air conductivity distributions in the source region. The incident electric field near ground is then computed by applying the Jefimenko's equation to both the primary and the secondary currents. When the near-ground transient field in the first millisecond is concerned, reflected field components are mingled with the incident field components radiated from the portion of source region away from the line-of-sight path. The electric field reflected by the ground is computed by transforming the incident field to the frequency domain and multiplying with the frequency-dependent reflection coefficient, then transforming back to the time domain. This paper is organized as follows: The theory to compute the primary current is briefly reviewed in Section 2, the method of solving for the air conductivity and the secondary current is presented in Section 3, the method to compute the reflected field is presented in Section 4, and simulation results are discussed in Section 5. Finally, some conclusions are drawn in Section 6.

Characteristics of Narrow Bipolar Pulses observed from lightning in Sri Lanka

A detailed study on electric field characteristics of Narrow Bipolar Pulses (NBP) observed in Sri Lanka is presented here. NBPs analyzed in this work were recorded at a coastal location in the Southern part of Sri Lanka (Matara: 5.95 °N, 8.53 °E), from five highly active consecutive thunderstorm days during the month of May in 2013. The waveforms were recorded with a 10ns resolution within a 100ms time window. Both positive and negative NBPs were observed in this study with the negative type being the most frequent. Parameters presented in this study were the rise time (Tr), zero crossing time (Tz), the duration of slow front (Ts), the full width of half maximum (FWHM), the pulse duration and the ratio of amplitude of overshoot to the corresponding peak amplitude (Os/Pa). The corresponding average values of negative NBPs for these parameters were found to be 0.58µs, 3.01µs, 0.20µs, 1.38µs, 19.21µs and 0.19 respectively. Similarly, for positive events corresponding values were 1.38µs, 4.66µs, 0.48µs, 1.93µs, 16.42µs and 0.37 respectively. The above values conforms to a much narrower bipolar events when compared to previously reported values which is considered to be caused by the propagation effects of signals captured by the apparatus.