Quasi-static Electric Field Research Articles

Local Electric Field Enhancements of Two Closely Spaced Subwavelength Spheres in Microwaves

The local electric field enhancement (LEFE) among powdered metals or dielectrics in microwaves has been widely applied in many fields, but it is still a challenge to describe the LEFE intuitively. This article presents a simple model to predict the LEFE in two closely spaced subwavelength spheres in microwaves, based on the quasistatic electric field approximation and the dipole–dipole interaction. The results show that this LEFE is related to the radius of spheres, the separation distance, and the permittivity of spheres. The proposed model is able to predict the LEFE accurately if the electric length of the two spheres is within one-tenth of a wavelength when put in free space or a waveguide. The proposed model can benefit in predicting the LEFE in subwavelength metals or dielectrics, which can benefit a wide range of applications.

Axion-like particle generation in laser-plasma interaction

The hypothetical axion and axion-like particles, feebly coupled with photon, have not yet been found in any experiment. With the improvement of laser technique, much stronger but shorter quasi-static electric and magnetic fields can be created in laboratory using laser-plasma interaction, compared to the fields of large magnets, to help the search of axion. In this article, we discuss the feasibility of ALPs exploration using planarly or cylindrically symmetric laser-plasma fields as background and an x-ray free-electron laser as probe. Both the probe and the background fields are polarized such that the existence of ALPs in the corresponding parameter space will cause polarization rotation of the probe, which can be detected with high accuracy. Besides, a structured field in the plasma creates a tunable transverse profile for the interaction and improves the signal-to-noise ratio via phase-matching mechanism. The ALP mass discussed in this article ranges from 10−3 eV to 1 keV. Some simple schemes and estimations on ALP production and polarization rotation of probe photon are given, which reveals the possibility of future laser-plasma ALP source in laboratory.

A Method for Investigating Nanosecond Processes in Micropinch Discharge Plasma

The technique is described and the results of studies of the spatial structure and dynamics of X-ray sources in the plasma of a micropinch discharge are presented. The applied technique made it possible to temporarily link the process of electron acceleration in a quasi-static electric field of a resistive nature to the process of forming a microstretch in a Z-pinch in a medium of heavy elements with a nanosecond time resolution.

Efficient ion acceleration by multistaged intense short laser pulses

We present a computational study of laser-driven ion acceleration that optimizes a combination of target transparency and extended field acceleration at moderate relativistic intensity. Our scheme applies two sequential laser pulses irradiating a thin target foil along the same direction: The first pulse drives a rapid expansion of the target, while the second one drives a quasistatic electric field in the expanding target with increasing electron temperature. In our particle-in-cell simulations we observe proton peak energies and numbers enhanced by factors of up to 3 compared with regular target-normal sheath acceleration.Received 6 October 2020Accepted 4 May 2022DOI:https://doi.org/10.1103/PhysRevResearch.4.L032003Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasHigh-energy-density plasmasLaser driven ion accelerationAccelerators & BeamsPlasma PhysicsParticles & Fields

Effect of interfacial and edge roughness on magnetoelectric control of Co/Ni microdisks on PMN-PT(011)

Uniform magnetic behavior within arrays of magnetoelectric heterostructures is important for the development of reliable strain-mediated microdevices. Multiple mechanisms may contribute to observed nonuniform magnetization reversal including surface roughness, non-uniform strain, and fabrication induced imperfections. Here, Co/Ni microdisks of 7 µm diameter were produced on both [Pb(Mg1/3Nb2/3)O3]1−x–[PbTiO3]x with x = 0.3 nominal composition (PMN-30PT) (011) and Si substrates, and the out-of-plane magnetization reversal was characterized using magneto-optical Kerr effect (MOKE). Coercivity variation across the microdisks within the arrays was observed on both the PMN-30PT and Si specimens with zero electric field applied. Co/Ni microdisks on a PMN-30PT substrate displayed relatively larger coercivity than those on a Si substrate due to the surface roughness effect. Quasistatic electric fields of varying magnitude were applied to the PMN-30PT substrate to assess the dependence of the coercivity on electric field induced strain. Our results indicate that while coercivity decreases with the increase of electric field induced strain, interfacial and edge roughness combine to realize a prohibitively large coercivity to overcome within the Co/Ni microdisks as well as a broad distribution of coercive field across a patterned microdisk array.

Особенности формирования спектров излучения двухчастичных наносистем в магнитном поле

A spectral model of luminescence of the two-component exciton-activated semiconductor quantum dot (QD) – layered plasmon composite nanoparticle (CNP) with a dielectric core and a conductive shell in an external magnetic field is constructed, taking into account the inhomogeneity of the quasi-stationary electric field generated by QD in the CNP region, outside the framework of the approximation of the dipole polarizability of the CNP. The tensor formalism of describing the characteristics of the field in each of the layers of the CNP, as well as outside the CNP, is used. It is established that with a change in the structure of the nanocomposite, the parameters of its core or shell layer, the spectral response of the system to external magnetic field action changes. It is shown that the special form of the response is associated with the characteristic magnetic properties of the nanoparticle components acquired (under the action of the field).

Features of the formation of radiation spectra of two-particle nanosystems in a magnetic field

A spectral model of luminescence of the two-component exciton-activated semiconductor quantum dot (QD) layered plasmon composite nanoparticle (CNP) with a dielectric core and a conductive shell in an external magnetic field is constructed, taking into account the inhomogeneity of the quasi-stationary electric field generated by QD in the CNP region, outside the framework of the approximation of the dipole polarizability of the CNP. The tensor formalism of describing the characteristics of the field in each of the layers of the CNP, as well as outside the CNP, is used. It is established that with a change in the structure of the nanocomposite, the parameters of its core or shell layer, the spectral response of the system to external magnetic field action changes. It is shown that the special form of the response is associated with the characteristic magnetic properties of the nanoparticle components acquired (under the action of the field). Keywords: plasma layered nanoparticle, spherical quantum dot, magnetic field, luminescence of a two-particle complex.

MEASUREMENT OF LEAKAGE CURRENTS AND QUASI-STATIONARY ELECTRIC FIELD IN THE SURFACE AREA OF THE ISS RS IN THE EARTH'S IONOSPHERE

The paper presents the results of analysis of electrical measurements performed in the space experiment "Impulse (stage 1)" on the Service module of the ISS RS. This experiment investigated the effects of the interaction of the charged component of the ionosphere to the surface of large KA, which is the ISS. This paper analyses the measurement of quasi-stationary electric field and current leakage, was, respectively, sensors of the vibration type and flat probes from the Complex control electrophysical parameters (CCEP), developed by SPJ MT. To study the dependence of measurements from the ionosphere flow direction to the surface of the ISS RS was installed two sets of sensors with the direction of the angle of "visibility" in the Nadir (towards the Earth) and to "satellite footprint " (against the velocity vector of the ISS). Carried out analysis of common regularities measurements depending on the sun-shadow environment on orbit ISS motions and depending on current geophysical dynamics of the ionosphere. Massive the measurements including more than 170 telemetric sessions were analyzed. More than 11000 hours of measurements current of leakage (or runoff current) and measurements of quasi-stationary electric field with discretization 1s and UT binding to each point were analysed. The data measurements, geophysical and orbital data were collected in an electronic album. It is shown that experimental data correlate with the crossing time of the ISS boundaries known geophysical structures: the noon Meridian, the Main ionospheric failure (MIF), the boundaries diffuse intrusion (BDI), the Equatorial Geomagnetic anomaly (EA). In this regard, despite the specificity of the ISS (the spacecraft super big sizes, the most complex spatial configuration) similar measurements, nevertheless, are quite suitable for monitoring researches of some features of an ionosphere at the level of F2 layer with a temporary scale from 1s and can be used for more detailed study of the geophysical structures and related effects in the ionosphere. In addition, the results obtained can be used for the analysis of disturbances of electromagnetic conditions near the surface of the ISS RS, for monitoring potential and currents of leakage on the surface of the ISS. Keywords: electrophysical measurements, sensors of the vibration type, flat probes, electric field, current leakage, geophysical structure, ionosphere

Flexible Noncontact Approach for Fault Location of Transmission Lines Using Electro-Optic Field Sensors

Locating faults in transmission lines is important for the safety and continuous operation of power systems. The existing fault location methods based on traveling waves mostly use current transformers to obtain the transient signals, which requires a direct connection with the live lines and therefore brings inconvenience to the installation, debugging, and maintenance. In this article, we propose a flexible noncontact approach for locating faults in transmission lines based on broadband electro-optic field sensors, where the noncontact fault location system can be easily installed, debugged, and maintained. The approach uses an electric field sensor to directly measure the quasi-static electric field generated by the faults, and then the associated time difference of arrival of the transients at two ends of a transmission line can be obtained. The approach is validated and tested by experiments both in laboratory and real 500 kV transmission lines. The artificial fault experiment shows a location error of approximately 200 m on a 177-km- long 500 kV power transmission line.

Energy Method for the Elliptic Boundary Value Problems with Asymmetric Operators in a Spherical Layer

Three-dimensional elliptic boundary value problems arising in the mathematical modeling of quasi-stationary electric fields and currents in conductors with gyrotropic conductivity tensor in domains homeomorphic to the spherical layer are considered. The same problems are mathematical models of thermal conductivity or diffusion in moving or gyrotropic media. The operators of the problems in the traditional formulation are non-symmetric. New statements of the problems with symmetric positive definite operators are proposed. For the four boundary value problems the quadratic energy functionals, to the minimization of which the solutions of these problems are reduced, are constructed. Estimates of the obtained quadratic forms are made in comparison with the form appearing in the Dirichlet principle for the Poisson equation

Slow and stopped light in dynamic Moiré gratings

We investigate a theoretical model for a dynamic Moir\'e grating which is capable of producing slow and stopped light with improved performance when compared with a static Moir\'e grating. A Moir\'e grating superimposes two grating periods which creates a narrow slow light resonance between two band gaps. A Moir\'e grating can be made dynamic by varying its coupling strength in time. By increasing the coupling strength the reduction in group velocity in the slow light resonance can be improved by many orders of magnitude while still maintaining the wide bandwidth of the initial, weak grating. We show that for a pulse propagating through the grating this is a consequence of altering the pulse spectrum and therefore the grating can also perform bandwidth modulation. Finally we present a possible realization of the system via an electro-optic grating by applying a quasi-static electric field to a poled $\chi^{(2)}$ nonlinear medium.

Характеристики опасных метеорологических явлений в Нижнем Новгороде по данным натурных наблюдений электрического поля

The characteristics of hazardous meteorological phenomena in Nizhny Novgorod city based on the electric field observations are obtained in the present paper. As a result of the analysis of quasistationary electric field variation experimental data together with the meteorological data, statistics of thunderstorm events were obtained and their classification was carried out. The data of field observations are compared with the results of numerical calculations based on the WRF model.

Thunderstorm and fair-weather quasi-static electric fields over land and ocean

Natural lightning and the associated clouds are known to behave differently over land and ocean, but many questions remain. We expand the related observational datasets by obtaining simultaneous quasi-static electric field observations over coastal land, near-shore water, and deep ocean regions during both fair-weather and thunderstorm periods. Oceanic observations were obtained using two 3-m NOAA buoys that were instrumented with Campbell Scientific electric field mills to measure the quasi-static electric fields. These data were compared to selected electric field records from the existing on-shore electric field mill suite of 31 sensors at Kennedy Space Center (KSC). Lightning occurrence times, locations and peak current estimates for both onshore and ocean were provided by the U.S. National Lightning Detection Network. The buoy instruments were first evaluated on-shore at the Florida coast, and the first system was calibrated for field enhancements and to confirm proper behavior of the system in elevated-field environments. The buoys were then moored 20 mi and 120 mi off the coast of KSC in February (20 mi) and August (120 mi) 2014. Diurnal fair-weather fields at both ocean sites matched will with each other and with those found during the Carnegie cruise, but mean values were 33% smaller, due at least in-part to constraints on the calibration procedure. Diurnal fair-weather fields variations at coastal and inland sites were a poorer match than offshore, likely because the offshore environment is “cleaner” with limited variations in local space charge, lower surface aerosol densities, little surface heating to disturb the surface charge layer during fair weather, and fewer local radioactive sources to modulate the near-surface electrical conductivity. Storm-related static fields were 4-5× larger at both oceanic sites than over land, likely due to decreased screening by near-surface space charge produced by corona current. The time-evolution of the electric field and field changes during storm approach are sufficiently different over land and ocean to warrant further study. This work shows the quality, accuracy, and reliability of these data, and has demonstrated the practicality of off-shore electric field measurements for safety- and launch-related decision making at KSC.

Bright betatron x-rays generation from picosecond laser interactions with long-scale near critical density plasmas

Our previous experimental and three-dimensional (3D) particle-in-cell (PIC) simulation results demonstrated that a well-directed electron beam with space charge of about μC and maximum energy of 100 MeV can be generated via a sub-petawatt, picosecond laser pulse interacting with a long-scale near-critical-density plasma. Effective laser energy coupling into hot electrons occurs in the presence of strong self-generated quasistatic electric and magnetic fields that confine fast electrons in relativistic ion channels. Here, we report results of 3D PIC simulations, which show that this direct laser accelerated electron beam can work as a compact high-brightness source of x rays. The relativistic electrons make betatron oscillations in the transverse fields of the ion channel and emit a bright broadband x-ray radiation with the critical energy of about 5 keV. Due to the huge number of accelerated electrons, our simulation shows that with a picosecond, 20 J laser pulse, an x-ray spectrum with a photon number of 7×1011 (>1 keV) can be generated, resulting into a peak flux of 2 ×108 photons/eV and a brilliance of 3.3×1020 photons/s/mm2/mrad2/0.1%BW.

Piezo-photo-thermoelasticity transport process for hyperbolic two-temperature theory of semiconductor material

A general solution for propagating waves in a generalized piezo-photo-thermoelastic medium for the one-dimensional (1D) problem under the hyperbolic two-temperature theory is investigated. The governing equations of the elastic waves, carrier density (plasma wave), quasi-static electric field, heat conduction equation, hyperbolic two temperature coefficient and constitutive relationships for the peizo-thermoelastic medium are obtained using Laplace transformation method in 1D. On the interface adjacent to the vacuum, mechanical stress loads, thermal and plasma boundary conditions are applied to obtain the main basic physical quantities in the Laplace domain. The inversion of Laplace transform by a numerical method is applied to obtain the complete solutions in the Laplace time domain for the main physical fields in this phenomenon. The effects on the force stress, displacement component, temperature distribution and carrier density of the thermoelastic, thermoelectric and hyperbolic two-temperature parameters by the applied force were graphically discussed.

Suppression of backward current in a low-magnetic-field foilless diode

An annular cathode is generally fixed on a cylindrical cathode holder in a magnetically insulated coaxial foilless diode. Electrons emitted from cathode plasmas or the cathode holder may easily move backward under the action of the quasi-static electric field and axial magnetic field, leading to backward current loss, which will seriously reduce the efficiency of high power microwave sources, especially under the condition of a low guiding magnetic field. A novel storage electrode immersed in the uniform magnetic field is proposed to suppress the backward current. Reverse electrons will be decelerated and blocked by the storage electrode. Under the guiding magnetic field of 0.66 T, over 66% of the backward current is suppressed (from 3.6 kA to 1.2 kA) when the storage electrode is used, and furthermore, the waveforms of the diode voltage and current are improved significantly.

The Discrepancy Between Simulation and Observation of Electric Fields in Collisionless Shocks

Recent time series observations of electric fields within collisionless shocks have shown that the fluctuating, electrostatic fields can be in excess of one hundred times that of the quasi-static electric fields. That is, the largest amplitude electric fields occur at high frequencies, not low. In contrast, many if not most kinetic simulations show the opposite, where the quasi-static electric fields dominate, unless they are specifically tailored to examine small-scale instabilities. Further, the shock ramp thickness is often observed to fall between the electron and ion scales while many simulations tend to produce ramp thicknesses at least at or above ion scales. This raises numerous questions about the role of small-scale instabilities and about the ability to directly compare simulations with observations.

Active auroral arc powered by accelerated electrons from very high altitudes

Bright, discrete, thin auroral arcs are a typical form of auroras in nightside polar regions. Their light is produced by magnetospheric electrons, accelerated downward to obtain energies of several kilo electron volts by a quasi-static electric field. These electrons collide with and excite thermosphere atoms to higher energy states at altitude of ~ 100 km; relaxation from these states produces the auroral light. The electric potential accelerating the aurora-producing electrons has been reported to lie immediately above the ionosphere, at a few altitudes of thousand kilometres1. However, the highest altitude at which the precipitating electron is accelerated by the parallel potential drop is still unclear. Here, we show that active auroral arcs are powered by electrons accelerated at altitudes reaching greater than 30,000 km. We employ high-angular resolution electron observations achieved by the Arase satellite in the magnetosphere and optical observations of the aurora from a ground-based all-sky imager. Our observations of electron properties and dynamics resemble those of electron potential acceleration reported from low-altitude satellites except that the acceleration region is much higher than previously assumed. This shows that the dominant auroral acceleration region can extend far above a few thousand kilometres, well within the magnetospheric plasma proper, suggesting formation of the acceleration region by some unknown magnetospheric mechanisms.

The influence of the magnetic field on the quasistationary electric field penetration from the ground to the ionosphere

A quantitative model of the penetration of a quasistationary electric field from the Earth’s surface into the ionosphere with an inclined magnetic field has been developed. The results of the three-dimensional model are simpler regarding interpretation and explanation than those dimensional ones. The electric conductivity problem is solved using Fourier transform at each height. The space distributions of the electric field strength and the current density are calculated. The current lines are plotted. The electric field strength in the ionosphere is in the microvolt per meter range when it is about 100 V/m in the air near ground. The known approximate estimates of decrease in the electric field penetrating into the ionosphere with decrease in the magnetic latitude are confirmed and detailed. The penetration of the electric field and currents from the ground to the ionosphere through the atmospheric conductor cannot be a physical process which creates the observed ionospheric precursors of the earthquakes.

Flare energy release and avalanche ionization of plasma by runaway electrons in lower solar atmosphere

Abstract The analysis of the electron acceleration by the quasi-stationary sub-Dreiser electric fields in the lower solar atmosphere has been done. It has been shown that the Dreiser electric field turned out to be several orders of magnitude larger than coronal values due to the inelastic collisions between electrons and hydrogen atoms. The ionization of hydrogen atoms gives rise to the resulting secondary electrons, which become runaway under the action of sub-Dreiser electric fields. This causes an further avalanche-like ionization of the plasma and leads to the acceleration of the large number of fast electrons up to relativistic energies at small (≲ 100 km) distances.