Peak Electric Field Intensity Research Articles

Electric field simulation of multi-needle water bath electrospinning and the structural properties of SCN/PAN micro/nanofiber composite yarns

Multi-needle water bath electrospinning is one of the most efficient methods used to prepare micro/nanofiber composite yarns. The nanofiber structure can be targeted and regulated to obtain high-performance composite yarns. To explore the effect of the receiving distance on the structure and properties of micro/nanofiber composite yarns, polyacrylonitrile nanofibers were uniformly coated on silver-coated nylon yarn via a four-needle continuous water bath electrospinning method. The electric field distribution at different receiving distances was simulated by ANSYS finite element analysis software, and the effects of electric field distribution on the structure and properties of the micro/nanofiber composite yarns were studied. The results indicated that the peak electric field intensity appeared at the tip of the needles and decreased with the increase in the receiving distance. The receiving distance was constant, and the field intensity was lower when the direction of the centerline of the needle tip was farther away from the tip; however, the field intensity at the conductive core yarn was higher than that in the surrounding area (small spikes). The average field intensity of the small spikes at 180 mm was only 1/4 of that at 80 mm. When the receiving distance increased within a certain range (100∼140 mm), the nanofibers had a smooth surface and good separation, their diameters decreased continuously and the porosity changed inversely. With a further increase in the receiving distance, the nanofibers gradually bonded, their diameter increased and the porosity showed the opposite trend. The coating rate of the nanofibers showed a decreasing trend, and the mechanical properties of the micro/nano composite yarns were improved. When the receiving distance was 100 mm, the porosity reached 38.94%, and the breaking force, breaking elongation and breaking strength were 13.71 ± 1.36 cN, 22.76 ± 6.62% and 0.15 ± 0.02 cN·dtex−1, respectively. Upon consideration of all the above factors, the receiving distance of 100 mm is appropriate.

Numerical simulation of streamer discharge with different electrode shapes in C4F7N

In recent years, the environmentally friendly gas, C4F7N, has been recognized as a potential SF6 alternative gas due to its excellent insulation. To study the streamer discharge characteristics of different electrode shapes in C4F7N, a fluid model was established by COMSOL, and simulations were performed. Streamer discharge as a function of varying electrode shapes was analyzed, and the variation law of electric field intensity and photon flux was obtained, which serves as a theoretical basis for optical detection and reliable diagnosis of partial discharge. Simulation results demonstrate that under the same discharge conditions, the electric field inhomogeneity of the needle–plane model, rod–plane model, and ball–plane model decreased successively and the breakdown difficulty increased. With the increase in the applied voltage, the peak electric field intensity of the streamer head was found to increase, whereas an increase in the electrode spacing was found to decrease this property. The change in photon flux was found to be similar to the change in the electric field intensity.

Metal–ceramic composite structures for fabrication of high power density plasmonic devices

The recent decade brought many advances to plasmonics, but high power density plasmonic antennas designed to behave as heaters or operate in high temperature environments are still facing material stability challenges preventing their ultimate use. Gold has been the optimal choice among plasmonic materials but experiences morphology changes at temperature that result in device efficiency reduction and failure. Bulk titanium nitride has been explored as a solution but has deal-breaking tradeoffs in device quality factor. In this paper, we explore via proof-of-concept the use of a metal–ceramic composite structure to determine whether a bulk Au nanorod can provide strong plasmonic resonances while coated with an ultrathin conformal layer of titanium nitride or silica to provide morphological stability and sufficient plasmonic activity without excessive resonance quality degradation. We show SEM-level morphological stability for temperatures up to 500 °C with coatings below 4 nm. Computer modeling suggests the ultrathin titanium nitride has detrimental effects on the strong plasmonic resonances of a Au nanorod. We then looked into other possible coatings for solutions to stabilize high power density plasmonic antennas including plasmonic oxides, metal adhesion layers, and silica, the latter appearing to be the best option while lowering the overall peak electric field intensity, the silica increases the electric field intensity at its boundary.

Dynamically tunable ultralong photonic nanojets by a curved surface truncated dielectric microcylinder

As for microparticles (microspheres or microcylinders) that form photonic nanojets (PNJs) in the near field, a curved truncated dielectric microcylinder structure (CSTDM) is investigated by the finite element method which can form ultralong PNJs with the longest effective length: 209.49 Changing parameter h of the structure can realize long dynamic range tuning of the effective length of the PNJ. The effective length varies quasi-periodically with h; the law of the variation of main indicators of the microcylinder is further discussed, such as the effective length, the working distance, peak electric field intensity, and full width at half height.

Highly Sensitive ELC Resonator Based Differential Sensor

A highly sensitive electric LC resonator-derived differential sensor is proposed in this work, with the major focus on detecting the purity of any reference dielectric material. The proposed sensor is designed with two identical electric-LC (ELC) resonators being loaded on either side of a 50- $\Omega $ microstrip line such that the magnetic wall of the microstrip line is perfectly aligned with that of the resonators. The fabricated unloaded sensor is operating at a resonance frequency of 3.385 GHz, falling between the two ISM bands, exhibiting a peak electric field intensity at the capacitive gap. The working principle of the sensor is analyzed through a lumped element equivalent circuit model. Experimental validation is performed via the fabricated prototype of the developed sensor on Taconic TLY-5 substrate for various standard and unknown dielectric samples. For the accurate testing of various samples using the proposed sensor, an empirical relationship is developed relating the difference in the resonance frequencies of the unloaded and loaded resonators, and the sample thickness. Furthermore, a novel error modeling technique is also incorporated to take into consideration the effect of fabrication tolerance and any possible air gap between the sensor region and the test specimen. The proposed differential sensor possess a substantially higher normalized sensitivity of 4.915% (165 MHz in terms of absolute sensitivity), which is quite useful for applications requiring detection of purity of a product. Its applicability is validated here by detecting the presence of termite infestation in wood sample.

Optimal Design of Large Signal and Noise Performance of GaN/SiC Hetero-Structural IMPATT Diodes Based on QCDD Model

Successes of GaN and SiC electronics in high frequency, large power realm indicate that, the GaN/SiC hetero-structures can be used to design the impact avalanche transit time (IMPATT) diodes operating at Terahertz range, of which holds advantages over homo-structural counterparts in lower noise and reduced tunnel current. Here, the (n)GaN/(p)SiC and (p)GaN/(n)SiC double drift region (DDR) IMPATT diodes operating at 0.85 THz are proposed based on the quantum corrected drift-diffusion (QCDD) model, the performance parameters of static state, large signal and noise properties of the studied devices such as peak electric field intensity, breakdown voltage, optimal negative conductance, output power, conversion efficiency, admittance-frequency relation, quality factor, noise electric field, mean-square noise voltage per band-width and noise measure were numerically calculated and analyzed, which can guide to optimize the GaN/SiC IMPATT diodes.

Thermal Analysis of AlGaN/GaN High-Electron-Mobility Transistor and Its RF Power Efficiency Optimization with Source-Bridged Field-Plate Structure.

In this study, we consider the relationship between the temperature in a two-dimensional electron gas (2-DEG) channel layer and the RF characteristics of an AlGaN/GaN high-electron-mobility transistor by changing the geometrical structure of the field-plate. The final goal is to achieve a high power efficiency by decreasing the channel layer temperature. First, simulations were performed to compare and contrast the experimental data of a conventional T-gate head structure. Then, a source-bridged field-plate (SBFP) structure was used to obtain the lower junction temperature in the 2-DEG channel layer. The peak electric field intensity was reduced, and a decrease in channel temperature resulted in an increase in electron mobility. Furthermore, the gate-to-source capacitance was increased by the SBFP structure. However, under the large current flow condition, the SBFP structure had a lower maximum temperature than the basic T-gate head structure, which improved the device electron mobility. Eventually, an optimum position of the SBFP was used, which led to higher frequency responses and improved the breakdown voltages. Hence, the optimized SBFP structure can be a promising candidate for high-power RF devices.

2.07-kV AlGaN/GaN Schottky Barrier Diodes on Silicon With High Baliga’s Figure-of-Merit

In this letter, we demonstrate high-performance AlGaN/GaN Schottky barrier diodes (SBDs) on Si substrate with a recessed-anode structure for reduced turn-on voltage $V_{\mathrm {ON}}$ . The impact of the surface roughness after the recessed-anode formation on device characteristics is investigated. An improved surface condition can reduce the leakage current and enhance the breakdown voltage simultaneously. A low turn-on voltage of only 0.73 V can be obtained with a 50-nm recess depth. In addition, the different lengths of Schottky extension acting like a field plate are investigated. A high reverse breakdown voltage of 2070 V and a low specific ON-resistance of 3.8 $\text{m}\Omega \cdot \textrm {cm}^{2}$ yield an excellent Baliga’s figure of merit of 1127 MW/cm2, which can be attributed to the low surface roughness of only 0.6 nm and also a proper Schottky extension of 2 $\mu \text{m}$ to alleviate the peak electric field intensity in the SBDs.

Determination of a localized surface plasmon resonance mode of Cu7S4 nanodisks by plasmon coupling.

Plasmon properties such as peak position, extinction cross-section and local electric field intensity are strongly dependent on excited, localized surface plasmon resonance (LSPR) modes. In non-spherical copper chalcogenide nanoparticles, assignment of the LSPR peaks to the corresponding oscillation modes has been controversial and requires experimental verification. We determined the in-plane LSPR mode of roxbyite Cu7S4 nanodisks from the plasmon coupling effect of nanodisks in solution. Compared with individual Cu7S4 nanodisks, self-assembled Cu7S4 nanodisk arrays in chloroform exhibited a blue-shifted LSPR peak with weaker optical density. This strongly suggests that the singular LSPR peak in the near-infrared region mainly originates from the in-plane oscillation mode. In addition, we demonstrate that the same LSPR peak can be readily tuned by controlling the number of disks in the array.

Numerical simulation and experimental investigation of structural optimization of capacitance sensors for measuring steam wetness with different coaxial cylinders

Steam wetness is an important parameter, which is difficult to measure accurately. A simulation study is performed based on the theories of electrodynamics and hydrodynamics to investigate the characteristics of wetness capacitance sensors with different coaxial cylinders, and an experimental system and two capacitance probes were designed to measure steam wetness. Using a FLUENT user defined function (UDF) code, a program to compute the electric field was compiled which can transmit the data between the electric field and the flow field. The coupling of the steam flow field and the electric field within the sensors is investigated through numerical simulation. The results show that the electric field intensity decreases from the inner electrode plate to the outer electrode plate. The electric field intensity near the inner plate increases with increasing plate thickness while the sensor length has no effect on the electric field intensity distribution in the radial direction, but the peak electric field intensity decreases with increasing sensor length. The peak electric field intensity weakens with increasing electrode separation. Comparison of the numerical simulation results and the experimental results shows that the results of the simulation are similar to those of the experiments, with the output capacitance fluctuating around a fixed value as the steam flow rate changes and increasing linearly with increasing wetness. The maximum difference between the experimental data and the numerical simulation data is 0.78nF, which is a discrepancy of 19.8%.

Fine tuning slow group velocity and small pulse broadening of surface plasmon polaritons along metal–nonlinear Kerr medium interface

We propose and demonstrate a new method to fine control the group velocity of slow surface plasmon polaritons (SPPs) propagating in a metal–nonlinear Kerr medium (MNKM) waveguide by changing the incident peak electric field intensity. Tunable group velocity results from nonlinear dispersion relationship of waveguide induced by Kerr effect. The validity of this method is confirmed by numerical simulations with the finite-difference time-domain (FDTD). When the pulse with center wavelength 400nm and width 240fs propagates in MNKM waveguide of length 6μm, the largest pulse broadening is only 3.4% of the input pulse width. Our method offers a new avenue for potential applications of the tunable slow SPP pulse with small pulse broadening.

Influence of Different Buffer Layer on Intense Pulsed Field Emission of Carbon Nanotubes

In order to study influence of buffer layer on intense pulsed field emission (IPFE) of carbon nanotube films (CNTs), CNTs were synthesized on Si substrate with different buffer by pyrolysis of iron phthalocyanine (FePc). The buffer layer including Ni and Au/Ni were prepared by using electroless plating process. The surface morphologies of the films were characterized by field emission scanning electron microscopy (SEM). IPFE properties of CNTs were measured with a diode structure in single-pulse mode. It was found that the emission ability of CNTs were improved obviously by introducing buffer layer,and Au were better than Ni as buffer layer. At the same peak electric field intensity ~11.4 V/µm, The even turn-on field decreased from 6.7V/µm for Si- CNTs to 5.9 V/µm for Ni- CNTs to 4.6V/µm for Au- CNTs (the CNTs synthesized on Si substrate with Au/Ni buffer,Ni buffer and without buffer was abbreviated as Au-CNTs , Ni- CNTs,Si-CNTs, respectively) , and the peak emission current increased from 90A for Si- CNTs to 180A for Ni- CNTs to 260A for Au- CNTs.

Enhanced Light Focusing in Self‐Assembled Optoplasmonic Clusters with Subwavelength Dimensions

Compact metallo-dielectric hybrid clusters with subwavelength dimensions are fabricated by template guided self-assembly. Elastic and inelastic scattering spectroscopy and electromagnetic simulations reveal that hybrid clusters comprising TiO(2) nanoparticles on top of a cluster of strongly coupled gold nanoparticles harness synergistic electromagnetic interactions between the building blocks. This results in a boost of the peak electric field intensity and a redistribution of the field in the ambient medium. The complex phase landscape in the clusters features optical vortices that enhance the magnetic field.

Intensity of electric field radiating from high-power pulsed electromagnetic wave generator for use in biological applications

Cancer treatment is one of several new applications which use nanosecond and subnanosecond high-voltage pulses. This study focuses on the design of a compact highpower pulsed electromagnetic wave generator using a nanosecond pulsed power generator to apply a high-intensity electric field for the treatment of cancer; the pulses cause apoptosis in cancer cells. We applied an L-C inversion circuit to the pulsed power generator to obtain a voltage waveform with a single frequency, which is applied to an antenna. A water gap switch and water capacitors were used in the L-C inversion circuit to obtain a pulsed voltage with a frequency element of 250 MHz. In this experiment, an electromagnetic wave was radiated underwater by a loop antenna. A measuring double loop antenna placed 0.15 m and 0.3 m from the radiating antenna detected electric field intensities of 112 kV/m and 49 kV/m, respectively. A focusing bowl was attached to the radiating antenna to obtain a higher electric field. The electric field intensity of the radiating antenna with the focusing bowl, 300 kV/m, was 6 times higher than that without the focusing bowl. The intensity distribution of the electric field focused by the focusing bowl was measured. A measuring small loop antenna detected peak electric field intensity of 11.3 kV/cm at a focal point. Areas with electric field intensity greater than 10.8 kV/cm were approximately 5 mm square and 3 mm wide in the x-z plane and y-axis, respectively.

Effects of Chassis Currents on Hearing Aids Compatibility in the Handset

In this paper, we investigate the effects of the chassis wavemodes on the near-field electromagnetic intensities that contribute to hearing aid compatibility (HAC) tests at two different frequencies, 900 and 1880 MHz. For a comprehensive view, we also examine the far-field properties of the antenna total efficiency and bandwidth. Additionally, we examine the specific absorption rate in relation to the chassis wavemodes. The examined parameters are then related to the HAC. It was found that the chassis wavemodes have a significant effect on the antenna near-field performance, especially at the 900-MHz frequency range. We show that the optimum near-field antenna performance is achieved when the antenna resonant frequency is aligned with the chassis resonant frequency. With this, a decrease of about 50% can be achieved in the peak magnetic field intensity and a 30% decrease in the peak electric field intensity; hence, a better possibility in passing the HAC compliance tests. Moreover, controlling the chassis wavemodes has a similar effect to that of increasing the distance from the HAC scan plane—a rapid decrease in the field intensities can be achieved. Our analyses are done through simulations and these are validated against measurements.

Observation of cross-sectional electric field for GaN-based field effect transistor with field-modulating plate

Cross-sectional potential distribution of a GaN-based field effect transistor with a field-modulating plate has been measured by Kelvin prove force microscopy to investigate the effect of the field-modulating plate on an electric field under high-voltage biasing conditions. The observed potential distribution clearly revealed that the introduction of the field-modulating plate is effective in relaxing the peak electric field intensity at the drain side of the gate edge. Furthermore, the authors experimentally observed that the peak of electric field splits into two positions: drain-side edges of the gate and field-modulating plate electrodes.

Influence of electric current density on the bactericidal effectiveness of pulsed electric field treatments

A procedure applying equivalent pulsed electric field (PEF) treatments of similar peak electric field intensity, total treatment time, and treatment temperature, while delivering different amounts of electric current, was successfully developed in this study. Listeria innocua suspended in McIllvaine buffer was subjected to five PEF treatments, each with a peak electric field intensity of 28.85 kV/cm applied for 60 μs at 44.3 °C, with peak electric currents of 1.94, 2.20, 2.76, 3.51, and 4.21 kA, respectively. To apply the described treatments, the charge voltage, pulsing frequency, and initial temperature and electrical conductivity of the treated media were adjusted, based on calculations made using pertinent fundamental mathematical models. Neither the amount of electric current flowing through the treated product, nor the amount of delivered electric energy or the electric conductivity of the studied media showed any influence on the bactericidal effectiveness of the applied treatments within the studied range.

Analysis of electric field distribution in GaAs metal–semiconductor field effect transistor with a field-modulating plate

Electric field distribution in the channel of a field effect transistor (FET) with a field-modulating plate (FP) has been theoretically investigated using a two-dimensional ensemble Monte Carlo simulation. This analysis revealed that the introduction of FP is effective in canceling the influence of surface traps under forward bias conditions and in reducing the electric field intensity at the drain side of the gate edge under pinch-off bias conditions. This study also found that a partial overlap of the high-field region under the gate and that at the FP electrode is important for reducing the electric field intensity. The optimized metal–semiconductor FET with FP (FPFET) (LGF∼0.2 μm) exhibited a much lower peak electric field intensity than a conventional metal–semiconductor FET. Based on these numerically calculated results, we have proposed a design procedure to optimize the power FPFET structure with extremely high breakdown voltages while maintaining reasonable gain performance.

Multilayer Thin-film Polarizers with Reduced Electric-field Intensity

Abstract A methodology for designing pairs of layers to reduce the peak electric-field intensity in the critical layers of multilayer polarizers and oblique incidence reflectors is presented. It is shown that, for S-polarized radiation, the peak field intensity in the first high-index layer of a polarizer having (H/2 L H/2) as the basic stack, can be reduced by about a factor of seven by adding a single pair of layers on the side of incidence. Further, about a factor of four reduction in peak field intensity for S-polarized radiation occurs in the first high-index layer of a (HL)7H polarizer and oblique-incidence reflectors with the addition of three pairs of layers having different thicknesses. This methodology can also be applied for designing pairs of layers for reducing peak electric-field intensity for P-polarized radiation.

THEORY FOR PURE-TRAVELING-WAVE BOUNDARY-GUIDED TRANSPORT OF TRIBO-ELECTRIFIED PARTICLES

ABSTRACT Numerical simulations and limiting analytical solutions are used to picture synchronous and asynchronous domains of traveling-wave pumping of charge-conserving particles (having mass m, charge q, radius a and mobility b) in terms of the dimensiouless frequency Ω = (w/k)/(bE0), mass M = (m/q)(bE0)(bE0) and gravitational acceleration G= mg/qEo, where k and w are the wavenumber and angular frequency of the imposed wave and Eo is the peak electric field intensity. One- dimensional motions, which can be synchronous for o < Ω < 1 (have velocity w/k), have a subsynchronous velocity that decreases rapidly with increasing frequency for Ω > 1. Both synchronous and asynchronous motions can exist over a range Ω < Ω < 1, where Ω → 1 as M → 0. Similar identification of domains for two-dimensional pumping brings in the additional parameters G and an image force parameter I = q[(e/e0) − l]/[(ε/ε0 + + 1)]16πc2ε0E0 where c is the closest distance of the particle charge center from a dielectric of permittivity, ε, coating the electrodes. Masuda's electric curtain mode is fitted into the general picture. As the frequency is raised, synchronous hopping motions give way to an asynchronous mode which can be the “slow curtain mode”. It is shown that the “fast curtain mode” (which would also be asynchronous) does not exist. Depending on M, there is a range of frequencies over which both the synchronous and asynchronous modes can exist, depending on the initial conditions. For the one-dimensional and the curtain asynchronous modes, simple models are used to show that even at relatively low particle densities, the effect of fluid entrainmenl on the pumping is significant, generally tending to increase the velocity of asynchronous modes.