Electric Field Characteristics Research Articles

Assessment of nano dielectrics interface charge by electrokinetic sonic amplitude and atom force microscopy

Research has predicted the existence of the interface charges between nano particles and matrix polymers in nano dielectrics, which may become a dominant factor as the electrical properties of composites continue to improve. But until now, no experimental evidence has been found to prove this prediction. This research try to prove that the charging abilities of the nano particles in liquid suspension are related to that of polymeric nanocomposites, even more to find the existence evidence of interface charge in polymeric nanocomposites. Zeta potential of surface modified nano particles SiO 2 , and MgO/ paraffinic wax suspension systems have been measured by electrokinetic sonic amplitude (ESA) method to assess the charging properties. The average of zeta potential value of -62.8 mV and 2.1 mV of SiO 2 , and MgO/ wax suspension systems were obtained. The interface charge domains were detected by means of atomic force microscopy (AFM) lift model phase scanning of atomic flat surface of the corresponding polymeric nano composites. The interface charge domains have been found in SiO 2 / low density polyethylene (LDPE) nanocomposite but cannot be found in MgO/LDPE system, which agree with the tremendous deference of zeta potential of corresponding suspension. Three types of models are proposed to interpret the AFM phase scanning appearance of the domains. Measurement results of zeta potential and AFM phase scanning and j (current density)-E (electric field) characteristics of LDPE and two kinds of nano composites reveal that the interface charge zones would inhibit the conducting current densities of the composites, and the larger absolute value of zeta potential corresponds to the stronger inhibiting ability to the conducting current density in polymeric nanocomposites.

Effect of anatomical variability on electric field characteristics of electroconvulsive therapy and magnetic seizure therapy: a parametric modeling study.

Electroconvulsive therapy (ECT) and magnetic seizure therapy (MST) are conventionally applied with a fixed stimulus current amplitude, which may result in differences in the neural stimulation strength and focality across patients due to interindividual anatomical variability. The objective of this study is to quantify the effect of head anatomical variability associated with age, sex, and individual differences on the induced electric field characteristics in ECT and MST. Six stimulation modalities were modeled including bilateral and right unilateral ECT, focal electrically administered seizure therapy (FEAST), and MST with circular, cap, and double-cone coils. The electric field was computed using the finite element method in a parameterized spherical head model representing the variability in the general population. Head tissue layer thicknesses and conductivities were varied to examine the impact of interindividual anatomical differences on the stimulation strength, depth, and focality. Skull conductivity most strongly affects the ECT electric field, whereas the MST electric field is independent of tissue conductivity variation in this model but is markedly affected by differences in head diameter. Focal ECT electrode configurations such as FEAST is more sensitive to anatomical variability than that of less focal paradigms such as BL ECT. In MST, anatomical variability has stronger influence on the electric field of the cap and circular coils compared to the double-cone coil, possibly due to the more superficial field of the former. The variability of the ECT and MST electric fields due to anatomical differences should be considered in the interpretation of existing studies and in efforts to improve dosing approaches for better control of stimulation strength and focality across patients, such as individualization of the current amplitude. The conventional approach to individualizing dosage by titrating the number of pulses cannot compensate for differences in the spatial extent of stimulation that result from anatomical variability.

Current conduction in single-domain BiFeO3 thin films

Recently, the semiconducting characteristics of BiFeO3 thin films such as the photovoltaic effect or diode characteristics have been extensively investigated. However, the current conduction mechanism has not been completely clarified yet. In this study, the current conduction mechanism of the ideal BFO thin film, which has a single domain without conduction domain walls, such as 71 and 109° domain walls, has been investigated. The current density–electric field (J–E) characteristics of 100- to 1000-nm-thick BFO thin films and their temperature dependence in the range of 100–260 K have been carefully investigated. From these thickness and temperature dependences of the J–E characteristics, it can be concluded that the most probable mechanism of current conduction in the single-domain BFO thin film is space-charge-limited current (SCLC) with a shallow trap.

Characterization and modeling of electrical stress degradation in STI-based integrated power devices

Lateral DMOS transistors are widely used in mixed-signal integrated-circuit design as integrated high-voltage switches and drivers. The LDMOS with shallow-trench isolation (STI) is the device of choice to achieve voltage and current capability integrated in the basic CMOS processes. In this review, the electrical characteristics of the STI-based LDMOS transistors are investigated over an extended range of operating conditions through experiments and numerical analysis. The LDMOS high electric-field characteristics are explained to the purpose of investigating the effects on reliability and device performance under hot-carrier stress (HCS) conditions. A review of the HCS modeling is addressed to provide an understanding of the degradation kinetics and mechanisms. TCAD simulations of the degradation are finally proposed to explain the HCS effects on a wide range of biases and temperatures, confirming the experimental results.

Parameter dependence of the radial electric field in the edge pedestal of hydrogen, deuterium and helium plasmas

The characteristics of the edge radial electric field (Er) are studied in deuterium, hydrogen and helium plasmas at ASDEX Upgrade. The minimum of the Er well is analyzed as a function of pedestal parameters and the best correlation is found between the depth of the Er well and the ion pressure at the pedestal top. This result is consistent with Er being balanced by the main ion pressure gradient term. Studying the radial position of the Er minimum reveals that the Er well moves closer to the last closed flux surface the deeper the Er well is. This suggests that for deeper Er wells the distance between the steepest gradients in the ion temperature and ion density profile is reduced. The width of the Er well shows no significant variations despite changing the ion temperature, magnetic field and plasma particle species. At AUG, the Er well is on average 1.2 cm wide. A multi-machine comparison supports a machine size scaling of Er and indicates that the Er shear layer covers the outer 2% of the plasma minor radius independent of the size of the machine. Based on this scaling, the width of the Er well in ITER is estimated to ∼4 cm.

Space charge, conduction and photoluminescence measurements in gamma irradiated poly (ethylene-2,6-naphthalate)

Polyethylene naphthalate (PEN) thin films were subjected to gamma rays at different doses and changes in both the dielectric and photophysical properties were investigated. Samples were irradiated in air at room temperature by means of a 60Co gamma source at a dose rate of approximately 31Gy/min. Total doses of 650kGy (344h) and 1023kGy (550h) were adopted in this work. The space charge profiles and residual electric field of virgin material and material exposed to these representative doses, obtained after 30min of depolarization following field application in the range 40–200kV/mm, have been examined by Focused Laser-Intensity Modulation Method (FLIMM). The dependence of space charge density with electric field values and irradiation dose is analyzed. Under high DC voltages and after irradiation, PEN tends to accumulate space charge. Space charge versus electric field and current-field characteristics issued from FLIMM method and conduction measurements exhibit good agreement. The high radiation resistance of PEN film is highlighted.

On Statistical Characteristics of Electric Fields of the Thunderstorm Clouds in the Atmosphere

A series of features of the spectral characteristics of thunderstorm-cloud field perturbations is specified on the basis of long-term ground-based measurements of the electric field at remote locations. A significant increase in the spectral density of the electric-field variations during the thunderstorm has been observed. Maximum increase due to the pulsed field component, which is related to the lightning discharges, is observed in the fluctuation-period range from tens of seconds to several minutes. A significant increase is also observed in the range 0.5–1.5 mHz (10–30-min periods) in which the spectral density is increased by more than a factor of 104, whereas the increase factor at the lower frequencies is equal to 100 (about 10 times for the field). Quasimonochromatic components (with 10–20-min periods) in the frequency fluctuation spectra of an electric field of the powerful thunderstorm clouds, which drift by frequency at the cloud initiation, maturity, and dissipation stages are found. It is shown that presentation of the sequence of the pulsed field perturbations related to the discharges in the form of a pulse flow with independent intervals (Poisson flow) agrees with the form of the fluctuation spectrum of the observed field and leads to an estimate of 10 s for the average relaxation (regeneration) time of the field in the thunderstorm-cloud vicinity after the discharge.

Power-Law Relationship Between Critical Current Density, Microstructure, and the n-Value in MgB2 Superconductor Wires

Dissipation-free MgB2 superconducting wires are valuable in terms of practical applications. Herein, we have found a strong correlation between critical current density (J c ) and the n-value extracted from the electric field versus current density characteristic. The power-law relationship (m) between the J c and the n-value, $n \propto J_{c}^{m}$ , represents a critical index which is strongly dependent on operating temperatures.

Multi-State Electric Field Analysis of 1-Tower-Double-Circuit HVDC Transmission Lines Based on Charge Simulation Method

Currently, there is little experience about design of the 1-tower-double-circuit DC transmission lines. But the electromagnetic field distribution under its lines is complicated. In order to study the nominal electric field distribution of 1-tower-double-circuit DC transmission lines under different situations and a variety of operating conditions, the currents with analytical solutions are used to simulate the discrete or uneven distributed continuous charge. In the works within an acceptable range, the linear equations are built to solve simulation charge according to the electromagnetic theory. And ground nominal electric field of 1-tower-double-circuit DC transmission lines is calculated. The nominal electric field distribution extreme value extreme under different arrangements and nominal electric field distribution under a variety of operating conditions are analyzed comparatively. In this paper, the results show that the arrangements of lines have effects on the distribution characteristics of nominal electric field in normal condition. When monopole or bipolar or the bipolar of one line doesnt work, the change of nominal electric field is pronounced, but their extremes reduce.

Impact of the Insulator on the Electric Field and Generation Characteristics of Vacuum Arc Metal Plasmas

The field electron emission plays a vital role in the process of vacuum discharge breakdown. The electric field strength at the cathode tip is significant to the generation characteristics of vacuum arc metal plasmas. To increase the field strength at the cathode tip, a coaxial electrode plasma source was employed with an insulator settled between the electrodes. The math expression of the field strength is derived based on the Gauss theory. The impact of the insulator on the electric field and parameters of plasmas were investigated by MAXWELL 3D® simulation software and the Langmuir probe. In addition, a composite insulator was adopted to further strengthen the field strength. A series of experiments were performed to focus on the role of the composite insulator in detail. The experimental and simulation results indicate that, a reasonable layout of the insulator, especially the composite insulator, can effectively increase the field strength at the cathode tip and the plasma density.

Calculation of Electric Field Characteristics of Insulator Under Sandstorm Condition

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. DOI : http://dx.doi.org/10.11591/telkomnika.v12i2.3902

Tempo-spatially Resolved Ozone Characteristics During Single-electrode Dielectric Barrier Discharge (SE-DBD) Operation against Metal and Porcine Skin Surfaces

Ozone is a major component produced by low-temperature plasmas operating in oxygen-containing gas mixtures. For correlation with biological or clinical results of plas- ma medical therapies as well as for evaluation of application security, tempo-spatially resolved ozone concentrations need to be considered. When operating a single-electrode dielectric barrier discharge (SE-DBD), the electric field characteristics are dependent on the geometrical setup as well as the electrical properties of the counter electrode. Thus, the counter electrode also affects the plasma input power and hence the total production of chemical species. Therefore, we studied the power input and the tempo-spatial characteristics of ozone concentrations during operation of a SE-DBD operated at voltage pulses in the µs regime against a clean metal electrode and a metal electrode covered with porcine skin samples. At energy densities of up to 1.85 J/cm 2 , the ozone concentrations in the plasma volume amount to as much as 293 ppm whereas at a distance of 5 and 20 cm, respectively, from the discharge, concentrations have decreased beneath recom- mended safety limits of 0.1 ppm. Furthermore, significantly lower ozone concentrations could be observed when skin samples were used as part of the counter electrode.

Penetration electric field characteristics of dual plates with narrow slots for the incident plane wave

Penetration electric field characteristics of dual plates with narrow slots for the incident plane wave

Analysis of Distribution, Pattern, and Vector of Electric Field in the Inter Phases Region of Three-phase Gas Insulated Switchgear

This paper deals with the electric field characteristics in the inter-phases region of three-phase gas insulated switchgear (GIS). The electric field in a three-phase construction of a simplified GIS model was analyzed. The results show that in the inter- phases region the direction and the magnitude of electric field vector varies with the location of the observation point while in the phase-enclosure region the direction of the electric field vector tends to linear and constant. There is no zero electric field on the particle tip of a particle in the inter-phases region, except S90 particle. There is zero electric field on the particle tip of a particle in the phase-enclosure region every half cycle of applied voltage. The maximum electric field of the particles on the inter-phases region generally is higher than one of the particles on the phase-enclosure region. The electric field vector locus in the inter-phases region varies: linear, elliptic, or circular while one in phase-enclosure region is constant and linear.

Remote sensing of a NTC radio source from a Cluster tilted spacecraft pair

Abstract. The Cluster mission operated a "tilt campaign" during the month of May 2008. Two of the four identical Cluster spacecraft were placed at a close distance (~50 km) from each other and the spin axis of one of the spacecraft pair was tilted by an angle of ~46°. This gave the opportunity, for the first time in space, to measure global characteristics of AC electric field, at the sensitivity available with long boom (88 m) antennas, simultaneously from the specific configuration of the tilted pair of satellites and from the available base of three satellites placed at a large characteristic separation (~1 RE). This paper describes how global characteristics of radio waves, in this case the configuration of the electric field polarization ellipse in 3-D-space, are identified from in situ measurements of spin modulation features by the tilted pair, validating a novel experimental concept. In the event selected for analysis, non-thermal continuum (NTC) waves in the 15–25 kHz frequency range are observed from the Cluster constellation placed above the polar cap. The observed intensity variations with spin angle are those of plane waves, with an electric field polarization close to circular, at an ellipticity ratio e = 0.87. We derive the source position in 3-D by two different methods. The first one uses ray path orientation (measured by the tilted pair) combined with spectral signature of magnetic field magnitude at source. The second one is obtained via triangulation from the three spacecraft baseline, using estimation of directivity angles under assumption of circular polarization. The two results are not compatible, placing sources widely apart. We present a general study of the level of systematic errors due to the assumption of circular polarization, linked to the second approach, and show how this approach can lead to poor triangulation and wrong source positioning. The estimation derived from the first method places the NTC source region in the dawn sector, at a large L value (L ~ 10) and a medium geomagnetic latitude (35° S). We discuss these untypical results within the frame of the geophysical conditions prevailing that day, i.e. a particularly quiet long time interval, followed by a short increase of magnetic activity.

Characteristics of Electric Field and Radiation Pattern on Different Locations of the Human Body for In-Body Wireless Communication

An in-body wireless communication system has attracted increasing attention because it can replace the connectivity of biological telemetry monitoring. However, the human body is a very complex environment (lossy, dispersive, and inhomogeneous) and affects the electromagnetic (EM) wave in the near field. Moreover, the entire human geometry affects the radiation pattern in the far field. This communication presents the behavior of the EM wave in the near and far fields at 2.45 GHz when a dipole antenna (used as an implantable antenna) is embedded in the vicinity of the clavicle, upper arm, lower arm, and hand of a human body. The effect on the electric field and radiation performance is simulated by the finite-difference time-domain method. By introducing a three-layered phantom, the antenna performance is confirmed. Moreover, the measured and simulated results are in good agreement with each other. The information derived from this study can be used in the evaluation of the link budget of in-body wireless communication.

Role of cellulose crystallites in the polarization of a biopolymer composite: Wood in a nonuniform temperature field

Polarization phenomena caused by the presence of temperature gradients in a biopolymer such as wood are considered. It is shown that cellulose crystallites are centers of polarization in the fiber-forming part of the considered biocomposite. The relation for elementary polarization is obtained. It is proposed that the supermolecular structure of cellulose in samples of wood be studied by measuring the electric field characteristics of a thermal polarization nature.

Characteristics of penetration electric fields to the equatorial ionosphere during southward and northward IMF turnings

The signatures of abrupt turnings of the vertical component of the interplanetary magnetic field (IMF), Bz, can be seen at equatorial latitudes through the prompt transmission of high‐latitude electric fields to the lower latitudes, called as prompt penetration electric field (PPE). The present work studies the signatures of PPE in daytime equatorial electrojet (EEJ) index derived in the Indian sector during 2001–2005. The signatures are observed in polar (PCN index) and equatorial (EEJ index) ionosphere almost instantaneously (<1 min). The communication time of 12±6 min is observed between bow shock nose and the equatorial ionosphere, and it is found to have inverse relationship with radial component of solar wind velocity during southward and northward Bz turnings which might indicate magnetosphere crossing time scale by solar wind. Ionospheric reconfiguration time during southward turnings shows inverse relationship with solar wind flow in contrast to northward turnings with “no relationship,” indicating differences in underlying physical mechanisms during both turnings. We observe no local time dependence (within 06–18 h) in conductivity‐corrected EEJ signatures associated with Bz turnings. Regression analysis between conductivity‐corrected EEJ and interplanetary electric field shows higher efficiency during northward turnings. However, further analysis investigating the effect of actual orientation of Bz indicates that the magnitude of northward Bz does not have influence on the ionospheric signatures. It is noticed that the response signatures are mainly controlled by the magnitudes of southward Bz. Thus, the present study signifies the role of inner magnetospheric shielding electric field in addition to ceasing of convection during northward turnings.

Enhancement of In-Field Current Transport Properties in GdBCO Coated Conductors by $\hbox{BaHfO}_{3}$ Doping

We have investigated the in-field current transport property in BaHfO3 doped GdBa2Cu3O7 - δ coated conductors in a wide range of temperatures and magnetic fields. Significant improvement of in-field critical current Ic was observed, e.g., Ic@77 K, 3 T = 93 A/cm-w, Ic@20nK, 17nT = 700 A/cm-w, which is a comparable value to that of Nb3Sn wire at 4.2 K. Enhancement of the irreversibility field was also observed. These results suggest that BaHfO3 is one of the most promising materials as effective artificial pinning centers and leads to the enhancement of in-field Ic. Furthermore, we have also shown that our analytical expression of electric field versus current density characteristics based on the percolation transition model [1-3] agrees well with the experimental results over a wide range of magnetic fields and temperatures. This analytical expression is useful for the design of superconducting devices because this allows us to predict the current carrying capability of coated conductors not only Jc but also n-value at arbitrary operating conditions of temperature and magnetic field.

CTL cell에서의 우세장 발생과 특성

CTL cell that is one of the standard electromagnetic generation equipment can measure the characteristic of the electromagnetic susceptibility and the electromagnetic interference. In case of being input the same magnitude signal with the phase difference of 0o or the phase difference of 180o at two input ports of CTL cell to be the fundamental resonant frequency(TE011) of 2.20GHz, the characteristics of the electric field and the magnetic field at the uniform area were measured. And, it measured the electric field characteristic due to the variation of the input power, the test position and the input frequency under the dominant E-field and the dominant H-field of CTL cell. Using these mesuremed data, it examined the operation characteristic and the available frequency band of CTL cell.