Harmonic Electric Field Research Articles

Analysis of Parametric Resonances in In-Plane Vibrations of Electrostrictive Hyperelastic Plates

Electrostriction is a recent actuation mechanism which is being explored for a variety of new micro- and millimeter scale devices along with macroscale applications such as artificial muscles. The general characteristics of these materials and the nature of actuation lend itself to possible production of very rich nonlinear dynamic behavior. In this work, principal parametric resonance of the second mode in in-plane vibrations of appropriately designed electrostrictive plates is investigated. The plates are made of an electrostrictive polymer whose mechanical response can be approximated by Mooney Rivlin model, and the induced strain is assumed to have quadratic dependence on the applied electric field. A finite element model (FEM) formulation is used to develop mode shapes of the linearized structure whose lowest two natural frequencies are designed to be close to be in 1:2 ratio. Using these two structural modes and the complete Lagrangian, a nonlinear two-mode model of the electrostrictive plate structure is developed. Application of a harmonic electric field results in in-plane parametric oscillations. The nonlinear response of the structure is studied using averaging on the two-mode model. The structure exhibits 1:2 internal resonance and large amplitude vibrations through the route of parametric excitation. The principal parametric resonance of the second mode is investigated in detail, and the time response of the averaged system is also computed at few frequencies to demonstrate stability of branches. Some results for the case of principal parametric resonance of the first mode are also presented.

The form of the magnetic fluid drop in a uniform harmonic electric field with the concentration of surface charge transportations

The form of the magnetic fluid drop in a uniform harmonic electric field with the concentration of surface charge transportations

On AC-Field-Induced Nonlinear Electroosmosis next to the Sharp Corner-Field-Singularity of Leaky Dielectric Blocks and Its Application in on-Chip Micro-Mixing.

Induced-charge electroosmosis has attracted lots of attention from the microfluidic community over the past decade. Most previous researches on this subject focused on induced-charge electroosmosis (ICEO) vortex streaming actuated on ideally polarizable surfaces immersed in electrolyte solutions. Starting from this point, we conduct herein a linear asymptotic analysis on nonlinear electroosmotic flow next to leaky dielectric blocks of arbitrary electrical conductivity and dielectric permittivity in harmonic AC electric fields, and theoretically demonstrate that observable ICEO fluid motion can be generated at high field frequencies in the vicinity of nearly insulating semiconductors, a very low electrical conductivity, of which can evidently increase the double-layer relaxation frequency (inversely proportional to the solid permittivity) to be much higher than the typical reciprocal RC time constant for induced double-layer charging on ideally polarizable surfaces. A computational model is developed to study the feasibility of this high-frequency vortex flow field of ICEO for sample mixing in microfluidics, in which the usage of AC voltage signal at high field frequencies may be beneficial to suppress electrochemical reactions to some extent. The influence of various parameters for developing an efficient mixer is investigated, and an integrated arrangement of semiconductor block array is suggested for achieving a reliable mixing performance at relatively high sample fluxes. Our physical demonstration with high-frequency ICEO next to leaky dielectric blocks using a simple channel structure offers valuable insights into the design of high-throughput micromixers for a variety of lab-on-a-chip applications.

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

We present the Kinetic-j code, a computational kernel for evaluating the linearized Vlasov equation with application to calculating the kinetic plasma response (current) to an applied time harmonic wave electric field. This code addresses the need for a configuration space evaluation of the plasma current to enable kinetic full-wave solvers for waves in hot plasmas to move beyond the limitations of the traditional Fourier spectral methods. We benchmark the kernel via comparison with the standard k→-space forms of the hot plasma conductivity tensor. Program summaryProgram Title:Kinetic-jProgram Files doi:http://dx.doi.org/10.17632/w6znwd42z8.1Licensing provisions: MITProgramming language: C++ / IDL / CUDA / PythonNature of problem: Configuration space evaluation of the linear, kinetic plasma current.Solution method: Direct numerical evaluation of the linearized solution of the Vlasov equation, i.e., provided a time harmonic wave electric field as input, evaluate the unperturbed Lorentz orbit of each phase-space (position and velocity) point trajectory and integrate over its time history, then take the first velocity moment to calculate current.Additional comments: This initial version is 1x-3v, and accepts input fields in either Cartesian or cylindrical coordinates. The code is hosted at https://github.com/ORNL-Fusion/kineticj.

Influence of the geometry and the frequency range on the interface delamination in smart patch/layer structures under combined dynamic loading

The paper deals with the interface behavior of a smart patch/layer lightweight structure subjected to combined time harmonic mechanical loading, electric field and environmental conditions. The applied dynamic shear-lag and Fourier method refer to the overlap zone of the considered structure. It gives a possibility to obtain solutions in a closed form for axial and shear stresses of the structure. The types of solutions obtained depend mainly on the adherends’ thickness, the frequency interval of applied dynamic loading and the shear modulus of the used adhesive. At a given constant ratio of thicknesses of the adherends, the frequency interval of the dynamic load can change drastically the type of solution of the considered system of ordinary differential equations. Theoretical predictions for single debond length of patch/layer structure at an elastic-brittle interface behavior are provided. The influence of the ratio of thicknesses of the adherends in PZT-5H/CFRP patch/layer structure and the frequency range of applied dynamic mechanical loading on the interface delamination is investigated. All results are illustrated in figures and tables and are discussed.

Kinetics of ion admixture in a native gas in an external harmonic electric field

We have considered the spatially homogeneous problem of the behavior of an ion admixture in a background gas after applying a harmonic electric field with arbitrary parameters for various laws of interaction of particles. The Boltzmann equation has been solved using the modified method of moments. The ion distribution function and its first moments have been analyzed. It has been shown that the universal analytic expressions for the current density and the ion energy that we derived earlier for a small field amplitude-tofrequency ratio have a considerably wider range of applications.

Magnetic fluid droplet in a harmonic electric field

A magnetic fluid droplet immersed in oil in an applied harmonic electric field is studied experimentally and theoretically. It is shown that deformations of the droplet observed experimentally are not described by the well-known theory. New double-layer droplet model which describes experimental data well is proposed.

Exact theory and numeric results for short pulse ionization of simple model atom in one dimension

Our exact theory for continuous harmonic perturbation of a one dimensional model atom by parametric variations of its potential is generalized for the cases when (a) the atom is exposed to short pulses of an external harmonic electric field and (b) the forcing is represented by short bursts of different shape changing the strength of the binding potential. This work is motivated not only by the wide use of laser pulses for atomic ionization, but also by our earlier study of the same model which successfully described the ionization dynamics in all orders, i.e., the multi-photon processes, though being treated by the non-relativistic Schrödinger equation. In particular, it was shown that the bound atom cannot survive the excitation of its potential caused by any non-zero frequency and amplitude of the continuous harmonic forcing. Our present analysis found important laws of the atomic ionization by short pulses, in particular the efficiency of ionizing this model system and presumably real ones as well.

Electric response of a magnetic colloid to periodic external excitation for different nanoparticles concentrations: Determination of the particles' effective charge

The effective electric charge of a nanoparticle in an ionic magnetic colloidal system (an ionic ferrofluid) is determined by using the impedance spectroscopy technique. The electric response of the samples to a harmonic external electric field excitation is described by means of the Poisson-Nernst-Planck model. The model proposed for the theoretical interpretation of the impedance spectroscopy data considers that the magnetic particles are electrically charged with H+ and have in their vicinity Cl− counterions, resulting in an effective charge Qeff. In the presence of an harmonic, in time, external field (frequency bigger than 104Hz) particles are assumed to be at rest, due to inertial reason. In this framework, the response of the cell is due to the H+ and Cl− present in the solution. From the spectra of the real and imaginary components of the electric impedance of the cell, by means of a best fit procedure to our model, we derive the effective electric charge of the magnetic particles and the bulk density of ions. From an independent measurement of the ζ-potential of the suspension, it is possible to calculate the hydrodynamic radius of the particle, in good agreement with that independently measured.

Internal Asymmetric Plasmonic Slot Waveguide for Third Harmonic Generation with Large Fabrication Tolerance

We propose an internal asymmetric plasmonic slot waveguide (IAPSW) containing two different materials in the slot region for third harmonic generation (THG) from 2.25 μm. In the IAPSW, the required phase matching condition is satisfied between the 0th-order mode at the fundamental frequency and 1st-order mode at the third harmonic frequency. By choosing an appropriate slot geometry and materials, the third harmonic electric field distribution can be engineered to significantly enhance the nonlinear overlap coefficient for THG. According to our simulation, a conversion efficiency up to 0.67 % with 1 W pump power is predicted within a ∼10 μm IAPSW. Additionally, the waveguide shows large fabrication tolerance in terms of geometry parameters. The proposed waveguide can find potential applications for high-speed all-optical signal processing.

Dielectric liquid drop in a harmonic electric field

The problem of the shape of a liquid drop and flows inside and outside the drop in a harmonic electric field is theoretically considered using the small-parameter expansion method. Taking the second-order terms into account makes it possible to consider charge transport over the drop surface.

The Langmuir waves associated with the 1 December 2013 type II burst

AbstractThe Langmuir waves associated with an interplanetary type II source region are presented. The type II burst was first observed on 29 November 2013 by STEREO A and B, with the shock crossing STEREO A on 1 December 2013. In the foreshock region upstream of the shock, 11 Langmuir‐like waveforms were recorded by STEREO A's Time Domain Sampler on three orthogonal antennas. The observed Langmuir wave electric fields are of large amplitude and aligned with the background magnetic field. Some of the waveforms show evidence of electrostatic decay, and several are consistent with Langmuir eigenmodes of density wells. Harmonic electric fields are observed simultaneously with the Langmuir waveforms and are consistent with fields produced by nonlinear currents. The beam speeds vb exciting the Langmuir waves are estimated from the waveform data, yielding speeds vb≈ (0.01–0.04)c. These are consistent with previous observations. The beam speeds are slower than those associated with type III solar radio bursts, consistent with the Langmuir wave electric fields being field aligned. The evidence found for electrostatic decay and against strong perpendicular fields, and so low‐wave number Langmuir/z‐mode waves, suggests that the dominant emission mechanisms for this type II foreshock involve electrostatic decay and nonlinear wave processes, rather than linear‐mode conversion. Harmonic radio emission via antenna mechanisms involving Langmuir waves remains possible.

Model of third harmonic generation and electric field induced optical second harmonic using simplified bond-hyperpolarizability model

We report for the first time a comprehensive study of the fourth rank tensor describing third harmonic generation (THG) and electric field induced second harmonic (EFISH) in centrosymmetric material from two different viewpoints: Group Theory (GT) and the Simplified Bond Hyperpolarizability Model (SBHM). We show that the fourth rank tensor related to THG and direct current (DC) EFISH can be reduced to two independent elements whereas SBHM always gives only one, reproducing perfectly well EFISH experimental results in Metal Oxyde Semiconductor (MOS). We argue that it is possible to reduce the fourth rank tensor describing EFISH to a third rank tensor and further deliver a classical explanation of EFISH regarding symmetry breaking where the term containing $r^3$ in the potential immediately leads to second harmonic generation (SHG).

Evolution of an ion admixture in an AC RF electric field

We consider the spatially homogeneous problem of the behavior of an ion admixture after the application of a harmonic electric field for various laws of interaction of ions with atoms. The expansion is performed in parameter α, which turns out to be small for a low electric field strength or at a high frequency. We use the special normalization that has been introduced earlier, in which the mobility in a weak electric field is equal to unity. It is shown that the time dependences of electric current at any frequency for any total energy acquired by ions at high frequencies become universal in this normalization and are independent of the interaction cross section. It is shown how the correction to the transverse energy of ions is accumulated. The behavior of the ion distribution function is analyzed. A simple method is proposed for determining the effective time between collisions for any law describing the interaction.

An analytic study of TTF of standing wave RF gap based on Bessel–Fourier expansion

Transit time factor (TTF) is important in design and simulation of standing wave RF gaps. The TTF is usually constructed on the basis of a square wave model, and it is always expanded as a function of reduced velocity and structure factors. In order to express the particle׳s motion more authentically, the TTF is studied based on the Bessel–Fourier (B–F) expansion which is realized in BEAMPATH code. By expanding square wave electric field into harmonic electric fields, the voltage component and the TTF component of each order are obtained from corresponding harmonic electric field. The ratios of each order of voltage components and integral voltage form the weights working as coefficients of TTF components. Consequently, the effective resultant TTF depends on not only the particle׳s velocity and the structure factors, but also the RF phase the particle experiences. Simple expressions are derived after simplifying the complicated TTF equation in this paper.

Estimation of the Engineering Critical Current Criteria for HTS Wire Carrying an Alternating Current

This paper deals with a method to estimate the engineering critical current criteria for high temperature superconducting (HTS) wire in alternating current (ac) operation. There are plenty of high temperature superconducting devices used in ac operation, such as superconducting fault current limiters and superconducting cables. However, the operating currents of those ac superconducting devices are mostly designated by the critical current measured in direct current operation based on International Electrotechnical Commision (IEC) 61788-3, so the engineering critical current criteria of the HTS wire for ac operation is needed. In this paper, the engineering critical current criteria of HTS wires for ac operation are estimated considering the odd harmonic electric fields, the calculated ac loss, and the temperature. The authors expect that the method and approaches used in this study will help to estimate the engineering critical current and to decide the operating currents of HTS applications.

Harmonic waves and sheath rectification in type III solar radio bursts

AbstractIn type III solar radio bursts and planetary foreshocks, Langmuir waves are produced by electron beams and converted partially to radio waves by linear and nonlinear processes. Lower amplitude second harmonic electric fields are observed simultaneously during the most intense Langmuir wave events in type III source regions. The electric fields at the harmonic frequencies can arise from various mechanisms, such as radio wave emission by either coalescence or antenna mechanisms, nonlinear currents, harmonics of Langmuir waves, electron trapping in Langmuir wave potentials, and Langmuir wave rectification at the sheath surrounding the spacecraft, or they can result from instrumental harmonics. In this paper the relative powers and electric field vectors of Langmuir waves and the harmonic fields are compared for multiple events. The structure of the harmonic field is shown to be determined by the Langmuir waveform, but the harmonic field direction is typically closely aligned with the solar wind flow. The magnitude, structure, and orientation of the harmonic fields is used to determine which processes are responsible. It is shown that the dominant process generating the observed harmonic fields is Langmuir wave rectification at the sheath surrounding the spacecraft.

Nonlinear and quasi-linear behavior of a curved carbon nanotube vibrating in an electric force field; an analytical approach

The nonlinear vibrational model of a slightly curved single-walled carbon nanotube (SWCNT) resting on a Winkler-type elastic foundation is developed using nonlocal Euler- Bernoulli elastic theory. The SWCNT is assumed to vibrate under an external harmonic electric force field and an analytical solution is proposed to obtain the nonlinear resonant frequencies. The results show good agreement with the numerical simulation and the obtained analytical frequency is completely related to the curvature of the nanotube. Our model predicts that although the model is nonlinear in nature, the curved SWCNT could behave linearly in a certain amount of curvatures and this quasi-linear vibrational behavior of curved SWCNT is a function of aspect ratio, nonlocal parameter, and stiffness of the foundation.

Ultrasensitive Optical Shape Characterization of Gold Nanoantennas Using Second Harmonic Generation

Second harmonic generation from plasmonic nanoantennas is investigated numerically using a surface integral formulation for the calculation of both the fundamental and the second harmonic electric field. The comparison between a realistic and an idealized gold nanoantenna shows that second harmonic generation is extremely sensitive to asymmetry in the nanostructure shape even in cases where the linear response is barely modified. Interestingly, minute geometry asymmetry and surface roughness are clearly revealed by far-field analysis, demonstrating that second harmonic generation is a promising tool for the sensitive optical characterization of plasmonic nanostructures. Furthermore, defects located where the linear field is strong (e.g., in the antenna gap) do not necessarily have the strongest impact on the second harmonic signal.

Oscillations of a layer of a crystal with cubic symmetry under the action of harmonic electric field

The linearized relations of the local gradient theory of nonferromagnetic dielectrics are used for the description of the mechanical vibrations of an infinite layer in a crystal with cubic symmetry that are induced by a time-dependent electric field. It is shown that, contrary to the classical linear theory of piezoelectricity, the local gradient theory describes the piezoelectric effect in highly symmetric crystals. When local mass displacements are taken into account, short waves become dispersive, which does not follow from the linear classical theory of piezoelectricity. The obtained results are compared with previously published results, which are based on Mindlin’s gradient theory of dielectrics. Some model parameters are evaluated.