Electric Field Measurements Research Articles

Four-Port Probe for Simultaneous Measurement of Electric and Magnetic Fields in Near-Field Scanning

Four-Port Probe for Simultaneous Measurement of Electric and Magnetic Fields in Near-Field Scanning

Development of an internet-of-things-based controlled-source ultrasonic audio frequency electromagnetic receiver

Abstract. Electromagnetic exploration, characterized by its low cost, wide applicability, and high operational efficiency, finds extensive applications in fields such as oil and gas exploration, mineral prospecting, and engineering geology. Traditional controlled-source electromagnetic detection methods are typically confined to operating frequencies below 250 kHz, resulting in insufficient detection accuracy for applications such as shallow- and intermediate-depth exploration, thereby constraining their performance in high-resolution imaging. To address these challenges, we propose a controlled-source ultrasonic audio frequency electromagnetic receive system based on the internet of things (IoT). We investigate cascaded digital filtering and sampling techniques to extend the receiver's sampling rate range, thereby elevating the operating frequency of controlled-source electromagnetic acquisition from the conventional maximum of 250 kHz to 1 MHz. The receiver achieves a sampling rate of up to 2.5 MHz, comprising three magnetic field measurement channels and two electric field measurement channels. The instrument is compact, lightweight, and capable of real-time data storage locally and real-time data transmission to an upper computer. Additionally, IoT technology is introduced, leading to the design of a cloud-based real-time remote control and data acquisition scheme. Experimental results demonstrate the stability of the instrument, meeting the requirements of field exploration.

Electric field and rotational temperature measurements based on electric field-induced coherent anti-Stokes Raman scattering in visible region (E-CARSv) in hydrogen discharge plasmas

Electric field measurements with a time resolution of a few nanoseconds using an electric field-induced coherent anti-Stokes Raman scattering in the visible region (E-CARSv) scheme were performed in a repetitively pulsed nanosecond discharge plasma in a 0.3-atm hydrogen environment. The rotational temperature was estimated using the E-CARSv scheme, which enables us to extract electric fields even at elevated gas temperatures. The estimated rotational temperature was 390 K, which reduced the E-CARSv signal intensity by approximately 50% when the rotational temperature was equal to the gas temperature. Considering the reduction, the peak electric field was estimated to be −1.4 kV/mm, which is 40% higher than −1.0 kV/mm, assuming no elevated temperatures.

Characterization of Electric Field Fluctuations in the High-Latitude Ionosphere Using a Dynamical Systems Approach: CSES-01 Observations

We present an analysis of the ionospheric electric field dynamics at high latitudes during periods of quiet and disturbed geomagnetic activity by exploiting recent advancements in dynamical systems and extreme value theory. Specifically, we employed two key indicators: the instantaneous dimension d, which evaluates the degrees of freedom within the system, and the extremal index θ, which quantifies the system’s persistence in a given state. Electric field measurements were obtained from the CSES-01 satellite at mid- and high latitudes in the Southern Hemisphere. Our analysis revealed that the instantaneous dimension increases upon crossing specific ionospheric regions corresponding to the auroral oval boundaries. Outside these regions, the instantaneous dimension fluctuates around the state-space dimension, suggesting an ergodic nature of the system. As geomagnetic activity intensifies, differences in the properties of various ionospheric regions persist, albeit with an increased system instability characterized by higher θ values, thus indicating the externally driven nature of the electric field response to geomagnetic activity. This study provides new insights into the spatial and temporal variability of electric field fluctuations in the ionosphere, highlighting the complex interplay between geomagnetic conditions and ionospheric dynamics.

Environment- and Conformation-Induced Frequency Shifts of C-D Vibrational Stark Probes in NAD(P)H Cofactors.

NAD(P)H cofactors are found in all forms of life and are essential for electron and hydrogen atom transfer. The linear response of a carbon-deuterium (C-D) vibration based on the vibrational Stark effect can facilitate measurements of electric fields for critical biological reactions including cofactor-mediated hydride transfer. We find both inter- and intramolecular electric fields influence the C-D frequency in NAD(P)H and nicotinamide-like models where the reactive C4-hydrogen has been deuterated. Hence, the C-D frequency can report both environmental electrostatics and conformational changes of the nicotinamide ring. Conformation-dependent effects are mediated through space as electrostatic effects, rather than through-bond. A Stark tuning rate of ∼0.57 cm-1/(MV/cm) was determined using both experimental and computational approaches, including vibrational solvatochromism, molecular dynamics simulations, and in silico Stark calculations. The vibrational probe's Stark tuning rate is shown to be robust and suitable for measuring fields along hydride transfer reaction coordinates in enzymes.

Ultrasensitive optical electric field sensor with temperature compensation for point-wise and quasi-distributed sensing.

A point-wise and quasi-distributed optical sensing technique with the Vernier effect is proposed and achieved by multiplexing Fabry-Perot interferometers (FPIs). The FPIs are fabricated by LiNbO3 (LN) crystals of varying lengths to enable simultaneous measurement of electric field (E-field) and temperature. Compared to the traditional bulk-type optical E-field sensors, this innovative sensor enables E-field measurement without being limited by half-wave voltage and effectively avoids the influence of natural birefringence. By an algorithm based on the Fourier transform, sub-FPIs are addressable, and their interference spectra can be demodulated independently, where any two FPIs are paired to generate the fundamental Vernier effect (FVE) or harmonic Vernier effect (HVE). Thus, the measurement sensitivities of FPIs can be significantly improved by monitoring the spectral shift of the envelope in the superimposed spectra. The quasi-distributed sensing experiment is conducted using three cascaded FPIs, yielding E-field sensitivities of 2.84 nm/E (FVE) and 3.37 nm/E (HVE), with a standard deviation (STD) of spectrum variation after temperature compensation below 3.19 × 10-3. The proposed multiplexing method is significant for practical applications of the E-field quasi-distributed measurement.

Exploring the inverse line-source scattering problem in dielectric cylinders with deep neural networks

Abstract This study presents a novel approach utilizing deep neural networks to
address the inverse line-source scattering problem in dielectric cylinders. By employing
Multi-layer Perceptron models, we intend to identify the number, positions, and
strengths of hidden internal sources. This is performed by using single-frequency
phased data, from limited measurements of real electric and real magnetic surface fields.
Training data are generated by solving corresponding direct problems, using an exact
solution representation. Through extended numerical experiments, we demonstrate
the efficiency of our approach, including scenarios involving noise, reduced sample
sizes, and fewer measurements. Additionally, we examine the empirical scaling laws
governing model performance and conduct a local analysis to explore how our neural
networks handle the inherent ill-posedness of the considered inverse problems.

An Antiferroelectric‐Coated Metal Foam Infiltrated with Liquid Metal as a Dielectric Capacitor

Nickel metal foams serve as both a substrate and bottom electrode for a dielectric capacitor using atomic‐layer deposition (ALD) and a eutectic gallium–indium (EGaIn) liquid metal (LQM) counter electrode. The conformal dielectric has a composition of 6.25% Al–HfO2 in the antiferroelectric phase, confirmed with polarization versus electric field measurements. Liquid EGaIn is pressure‐infiltrated within the coated foams to form the dielectric capacitor. Capacitances up to 4 μF are realized. Calorimetry of the infiltrated capacitor shows a 60 J g−1 latent heat upon melting a frozen EGaIn electrode, suggesting that the phase change can alleviate thermal deviations from pulsed power capacitor operation. Infiltrated capacitors are also shown to survive bending and freeze–thaw cycles. The metal foam–ALD dielectric–LQM capacitor shows a combined set of thermal and electrical properties not available in other classes of capacitors.

Rapid Transport of Energetic Electrons to Low L $L$‐Shells: The Key Role of Electric Fields

AbstractThe dynamics of the outer radiation belt are traditionally associated with wave‐particle resonant interactions, which provide local electron acceleration and losses through very low‐frequency waves, and electron radial transport by ultra‐low frequency waves. However, these processes cannot explain observations of rapid radial transport of energetic electrons (on a time‐scale of a couple of hours), deep into the inner magnetosphere (down to , mapping to magnetic latitude in the ionosphere). This transport is likely associated with strong convection electric fields forming around the plasmapause. To investigate these rapid, low‐latitude electron transport, we combine low‐altitude observations of energetic electron fluxes by the ELFIN CubeSats and DMSP satellites, SuperDARN measurements of ionospheric plasma flows (electric fields), and equatorial measurements of energetic electrons and electric fields by THEMIS. Our findings demonstrate that the rapid filling of the slot region by keV electrons is directly associated with electric field penetration to low latitudes (down to ). The proposed electron transport scenario, the direct penetration of energetic electrons by strong, localized electric fields, underscores the importance of ionosphere‐magnetosphere coupling in radiation belt dynamics.

Simultaneously measuring microwave electric fields at different frequencies by Rydberg-atom-based electrometry with Zeeman-resolved Autler–Townes splitting

We provide the simultaneous traceable measurements of microwave electric fields at two different frequencies by the electromagnetically induced transparency (EIT) and Autler–Townes (AT) splitting. A static magnetic field working together with a linearly polarized probe and coupling light prepares Rydberg atoms in Zeeman sublevels with maximal |mJ| in an atomic vapor cell. Using the EIT-AT splitting of these two maximal |mJ| states, the microwave electric fields at two different frequencies are simultaneously measured, in which their frequency difference can be adjustable within the linear range of magnetic field-induced level shifts. The proposed method provides a promising prospect for calibrating multiple microwave frequencies simultaneously in the future.

High sensitivity measurement of ULF, VLF, and LF fields with a Rydberg-atom sensor.

Fields with frequencies below megahertz are challenging for Rydberg-atom-based measurements, due to the low-frequency electric field screening effect caused by the alkali-metal atoms adsorbed on the inner surface of the container. In this paper, we investigate electric field measurements in the ultralow frequency (ULF), very low frequency (VLF), and low frequency (LF) bands in a Cs vapor cell with built-in parallel electrodes. With optimization of the applied DC field, we achieve high-sensitive detection of the electric field at frequencies of 1 kHz, 10 kHz, and 100 kHz based on the Rydberg-atom sensor, with the minimum electric field strength down to 18.0 μV/cm, 6.9 μV/cm, and 3.0 μV/cm, respectively. The corresponding sensitivity is 5.7 μV/cm/Hz1/2, 2.2 μV/cm/Hz1/2, and 0.95 μV/cm/Hz1/2 for the ULF, VLF, and LF fields, which is better than a 1-cm dipole antenna. Besides, the linear dynamic range of the Rydberg-atom sensor is over 50 dB. This work presents the potential to enable more applications that utilize atomic sensing technology in the ULF, VLF, and LF fields.

Model, design, and experiments of a field mill sensor for measuring high-voltage DC electric fields

Abstract In an attempt to measure the DC field intensity in the space below the high voltage transmission line, based on the principium of electrostatic induction, the DC-induced signal is transformed into an AC signal by continuously changing the relative area of the parallel plate capacitor, and then the signal is filtered and amplified. The measured value of the field to be measured is obtained from the amplitude of the output signal. The influences of the number of openings on the electric field distribution, the induced charge, and the output current in the adjacent space of the capacitive plate are studied by modeling and simulation. An experimental device is built to study the influence of the number of plate openings on the measurement results, and the simulation results are compared and analyzed. The calibration error of the field grinding sensor designed in this paper is about 6%, and the results show that the method can be applicable to the measurement of electric fields in DC transmission engineering.

Research on Spatial Electric Field Measurement of DC Line with MEMS Electric Field Sensor

Abstract As more and more UHVDC transmission lines are put into operation or under construction, the demand for space electromagnetic environment monitoring around transmission lines is increasingly urgent. In view of the lack of effective measuring instruments and methods for spatial DC electric field, this paper studies the spatial electric field measurement of DC line with a field mills MEMS electric field sensor. The relationship between the output current of the sensor and the intensity of the DC electric field is derived. In view of the error caused by the space accumulation of induced charge on the cover of the sensor, the structure of the sensor is further designed. In the new structure design, the shielding electrode grounding method is used to solve the accumulation of space charge on the shielding sheet. After calibrating and testing the response characteristics of the sensor in the performance test platform, the sensor is used in the DC line space electric field simulation test experiment. The output results of MEMS sensor at different spacing and voltage levels are consistent with the electric field distribution law. The measurement results prove that the designed structure is feasible to measure the space electric field of DC line, which is important for monitoring the electromagnetic environment.

Integrated Optical Waveguide Electric Field Sensors Based on Bismuth Germanate.

Bismuth germanate (Bi4Ge3O12, BGO) is a widely used optical sensing material with a high electro-optic coefficient, ideal for optical electric field sensors. Achieving high precision in electric field sensing requires fabricating optical waveguides on BGO. Traditional waveguide writing methods face challenges with this material. This study explores using femtosecond laser writing technology for preparing waveguides on BGO, leveraging ultrafast optical fields for superior material modification. Our experimental analysis shows that a cladding-type waveguide, written with a femtosecond laser at 200 kHz repetition frequency and 10.15 mW average power (pulse energy of 50.8 nJ), exhibits excellent light-guiding characteristics. Simulations of near-field optical intensity distribution and refractive index variations using the refractive index reconstruction method demonstrate that the refractive index modulation ensures single-mode transmission and effectively confines light to the core layer. In situ refractive index characterization confirms the feasibility of fabricating a waveguide with a refractive index reduction on BGO. The resulting waveguide has a loss per unit length of approximately 1.2 dB/cm, marking a successful fabrication. Additionally, we design an antenna electrode, analyze sensor performance indicators, and integrate a preparation process plan for the antenna electrode. This achievement establishes a solid experimental foundation for future studies on BGO crystal waveguides in electric field measurement applications.

Electrochemical survey of electroactive microbial populations in deep-sea hydrothermal fields

Electric discharge in deep-sea hydrothermal fields leads us to expect the existence of electroactive microbial ecosystems in the environments. Electrochemical properties such as electric field distribution on the seafloor and electrical conductivity of the rock can be useful indicators of searching electroactive microbial community in natural environments. We performed electric field measurements in deep-sea hydrothermal fields and collected rock samples by a remotely operative vehicle (ROV) operation. Several spots on the seafloor with strong electric fields were detected, which included both active hydrothermal vent areas and inactive sulfide deposits far from the vents. The electrical conductivity of the rock samples was correlated with the copper and iron sulfide content. Microbial community compositions of the rock samples were characterized by small subunit (SSU) rRNA gene amplicon sequencing analysis. The abundance of several microbial components, which are highly related to electroactive microorganisms such as Geobacteraceae and Thiomicrorhabdus, was affected by the electrical properties of rock samples. The results suggested that electrochemical properties on the seafloor would be related to the abundance of possible electroactive microbial populations, and that the electrochemical survey may be a powerful tool for exploring electroactive ecosystems.

Establishment of DC Electric Field Measurements by Linear Dipole Type Sensor System

Nowadays, electric fields above the ground are measured mainly by so‐called ‘field mill type’ sensor systems. However, their measurements are limited to vertical field component only due to its technical constraint. Out of necessity of measurements of electric field components in arbitrary directions in any spaces, a linear dipole type DC electric field sensor system, which can be immersed within a fully uniform electric field, was developed. However, it had been remained unknown whether its sensor output is parameter‐dependent or not, and unknown whether it can provide reliable intensity value of measured electric fields or not. In order to clarify these points, test observations of natural electric fields have been conducted by means of plural sensor systems having different values of parameter. Obtained electric field intensity derived from the observed data has shown a parameter‐dependence despite that it should be constant for any parameter values. After a detailed analysis of the effect of the parameter along the equivalent electric circuit of the sensor system, a field‐calibrating formula, which can make the sensor system to be parameter‐independent, has been found. Finally, the linear dipole type DC electric field sensor system for obtaining reliable electric field intensities has been established. © 2024 The Author(s). IEEJ Transactions on Electrical and Electronic Engineering published by Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

An optical measurement method of DC total electric field with space charges based on probe self-rotation modulation

Researching the measurement of DC total electric field with space charges (Poisson field) can help establish a monitoring system for the electromagnetic environment of UHVDC transmission lines and protect the health of the ecological environment. This paper proposes a DC total electric field optical measurement method based on the Pockels effect and probe self-rotation modulation. It can address the issues of internal charge drift and external charge accumulation in traditional optical probes when measuring DC electric fields with space charges. Theoretical analysis was conducted on measurement under probe rotation, and the optical modulation system was integrated into a probe with dimensions of 60 mm × 30 mm × 20 mm. A self-rotating platform for the probe was designed, and the influence of rotation mode on the results was analyzed. It was found that the sensitivity was higher when using the horizontal-horizontal mode. The signal processing system was tested, showing that the probe retained around 50 % of its original output when rotating at low speeds (frequency 1–3 Hz), fully meeting the measurement requirements. The test platform has been constructed, and the probe’s sensitivity was assessed under an AC electric field and validated under a DC electric field. Finally, the optical method proposed in this paper was used to measure the DC total electric field with space charges under a small model of a unipolar HVDC transmission line. Five locations under the line were selected as measurement points, and the results were compared with those obtained from a field mill probe and numerical simulation. This comparison indicates that the proposed method agrees with experimental and simulation results. The average sensitivity of the self-rotating optical probe was 3.71 mV/(kV/m). The error did not exceed 5 % in high-field strength areas (above 20 kV/m) and was also controlled within 15 % in low-field strength areas (below 20 kV/m).

The impact of electric field strength on the accuracy of boron dopant quantification in silicon using atom probe tomography

This study investigates the impact of the surface electric field on the quantification accuracy of boron (B) implanted silicon (Si) using atom probe tomography (APT). The Si Charge-State Ratio (CSR(Si) = Si2+/Si+) was used as an indirect measure of the average apex electric field during analysis. For a range of electric fields, the accuracy of the total implanted dose and the depth profile shape determined by APT was evaluated against the National Institute of Standards and Technology Standard Reference Material 2137. The radial (non-)uniformity of the detected B was also examined. At a higher surface electric field (i.e., a greater CSR(Si)), the determined B dose converges on the certified dose. Additionally, the depth profile shape tends towards that derived by secondary ion mass spectrometry. This improvement coincides with a more uniform radial B distribution, evidenced by desorption maps. In contrast, for lower surface electric fields (i.e., a lower CSR(Si)), the B dose is significantly underestimated, and the depth profile is artificially stretched. The desorption maps also indicate a highly inhomogeneous B emission localized around the center of the detector, which is believed to be an artifact of B surface migration on the tip of the sample. For the purposes of routine investigations of semiconductor devices using APT, these results illustrate the potential origin of quantification artifacts and their severity at different operating conditions, thus providing pathways towards best practices for accurate and repeatable measurements.

(Invited) Controlling Electric Fields and Hydration at Electrochemical Junctions Using Surfactants

Tuning the electrostatics and the water structure at the nm and sub-nm scales are two important frontiers towards the broader goal of controlling reactivity at interfaces. Surfactants offer a way to influence both the electrostatics and hydration of an electrochemical interface. Here we report measurements of local electric fields generated between layers of surfactants and an electrode without application of an external potential. We estimate the value of the electric field by measuring the vibrational frequency shift of a well-defined Stark probe that is adsorbed on the electrode. The field generated by the common quaternary ammonium surfactants in aqueous media is estimated to be in the order of 1 V/nm. We show that modest quantities of surfactants (50 mM) can produce polarizing fields similar to those produced by an electrode poised at -0.8 V vs. Ag/AgCl. Furthermore, we show that under electrochemical conditions, surfactants offer a way of modulating the water content near the electrode. In a mixture of water and DMSO, there are two forces that act upon the surfactants to drive them to the interface: they hydrophobic forces and the electrostatic forces from the electrode. We measure the surfactants at the interface as a function of these variables using surface enhanced IR spectroscopy, and arrive at quantitative comparisons between these two effects. These results help in understanding the design principles of modifying interfacial reactions via tailored surfactants.

3D modeling of deep borehole electromagnetic measurements with energized casing source for fracture mapping at the Utah Frontier Observatory for Research in Geothermal Energy

AbstractWe present a 3D numerical modelling analysis evaluating the deployment of a borehole electromagnetic measurement tool to detect and image a stimulated zone at the Utah Frontier Observatory for Research in Geothermal Energy geothermal site. As the depth to the geothermal reservoir is several kilometres and the size of the stimulated zone is limited to several 100 m, surface‐based controlled‐source electromagnetic measurements lack the sensitivity for detecting changes in electrical resistivity caused by the stimulation. To overcome the limitation, the study evaluates the feasibility of using a three‐component borehole magnetic receiver system at the Frontier Observatory for Research in Geothermal Energy site. To provide sufficient currents inside and around the enhanced geothermal reservoir, we use an injection well as an energized casing source. To efficiently simulate energizing the injection well in a realistic 3D resistivity model, we introduce a novel modelling workflow that leverages the strengths of both 3D cylindrical‐mesh‐based electromagnetic modelling code and 3D tetrahedral‐mesh‐based electromagnetic modelling code. The former is particularly well‐suited for modelling hollow cylindrical objects like casings, whereas the latter excels at representing more complex 3D geological structures. In this workflow, our initial step involves computing current densities along a vertical steel‐cased well using a 3D cylindrical electromagnetic modelling code. Subsequently, we distribute a series of equivalent current sources along the well's trajectory within a complex 3D resistivity model. We then discretize this model using a tetrahedral mesh and simulate the borehole electromagnetic responses excited by the casing source using a 3D finite‐element electromagnetic code. This multi‐step approach enables us to simulate 3D casing source electromagnetic responses within a complex 3D resistivity model, without the need for explicit discretization of the well using an excessive number of fine cells. We discuss the applicability and limitations of this proposed workflow within an electromagnetic modelling scenario where an energized well is deviated, such as at the Frontier Observatory for Research in Geothermal Energy site. Using the workflow, we demonstrate that the combined use of the energized casing source and the borehole electromagnetic receiver system offer measurable magnetic field amplitudes and sensitivity to the deep localized stimulated zone. The measurements can also distinguish between parallel‐fracture anisotropic reservoirs and isotropic cases, providing valuable insights into the fracture system of the stimulated zone. Besides the magnetic field measurements, vertical electric field measurements in the open well sections are also highly sensitive to the stimulated zone and can be used as additional data for detecting and imaging the target. We can also acquire additional multiple‐source data by grounding the surface electrode at various locations and repeating borehole electromagnetic measurements. This approach can increase the number of monitoring data by several factors, providing a more comprehensive dataset for analysing the deep‐localized stimulated zone. The numerical analysis indicates that it is feasible to use the combination of the energized casing and downhole electromagnetic measurements in monitoring localized stimulated zone at large depths.