Orthogonal Magnetic Field Components Research Articles

A Broadband Magnetic Probe with Multi-Components Measurement Characteristics

In this study, a broadband magnetic probe with multi-components measurement characteristics is presented. Two orthogonal detection loops with short-circuit characteristics are introduced into the bottom of the probe to simultaneously sense two orthogonal magnetic-field components. Multiple via fences are used to restrain unwanted electromagnetic modes. Two different vias are used to form these detection loops: a connected via is used as a part of the vertical loop, and a shorted via is used for shorting these detection loops. Due to the existence of these orthogonal loops, the proposed probe is capable of simultaneously measuring two orthogonal magnetic-field components. The working frequency band is from 1 MHz to 18 GHz. The simulated and measured results are shown, compared, and analyzed to demonstrate the design rationality.

A Resonant Magnetic Probe Capable of Simultaneously Measuring Two Orthogonal Magnetic-Field Components

A Resonant Magnetic Probe Capable of Simultaneously Measuring Two Orthogonal Magnetic-Field Components

New Resonant Probes With High Detection Sensitivity and Measurement Characteristic of Two Orthogonal Magnetic-Field Components

New Resonant Probes With High Detection Sensitivity and Measurement Characteristic of Two Orthogonal Magnetic-Field Components

Unbalanced Current Identification of Three-Core Power Cables Based on Phase Detection of Magnetic Fields

Identifying unbalanced phase currents is crucial for control and fault alarm rates in power grids, especially in urban distribution networks. The zero-sequence current transformer, specifically designed for measuring unbalanced phase currents, offers advantages in measurement range, identity, and size, compared to using three separate current transformers. However, it cannot provide detailed information on the unbalance status beyond the total zero-sequence current. We present a novel method for identifying unbalanced phase currents based on phase difference detection using magnetic sensors. Our approach relies on analyzing phase difference data from two orthogonal magnetic field components generated by three-phase currents, as opposed to the amplitude data used in previous methods. This enables the differentiation of unbalance types (amplitude unbalance and phase unbalance) through specific criteria and allows for the simultaneous selection of an unbalanced phase current in the three-phase currents. In this method, the amplitude measurement range of magnetic sensors is no longer a critical factor, allowing for an easily attainable wide identification range for current line loads. This approach offers a new avenue for unbalanced phase current identification in power systems.

A Broadband Multicomponent Magnetic Probe With Improved Electric-Field Suppression Performance

This article presents a broadband multicomponent magnetic probe with improved electric-field suppression performance. First, two orthogonal sensing loops were introduced into a magnetic probe to capture simultaneously two orthogonal magnetic-field components. Then, a via array and fence were used to adjust impedance matching and restrain unwanted electromagnetic modes, respectively. In addition, shielding vias were arranged on the upper part of these loops to improve electric-field suppression performance. As a result, high electric-field suppression was obtained in the composite probe using shielding vias. Finally, the proposed magnetic probe was simulated, fabricated, and tested to verify the design’s rationality.

A Composite Probe Capable of Simultaneously Measuring Two Orthogonal Magnetic-Fields

In this brief, a broadband composite probe capable of simultaneously measuring two orthogonal magnetic-fields is proposed. A pair of center orthogonal detection loops are utilized to capture two orthogonal magnetic-field components ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$H_{x}$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$H_{y}$ </tex-math></inline-formula> ). In order to suppress undesired electromagnetic wave modes, two rows of via fences is placed on both sides of the probe. A pair of 2.92mm vertical compression-mount precision test connectors are used to achieve the good impedance matching. In order to verify the rationality of design, the composite probe is simulated, measured and studied. Compared with the conventional single-component probe, the proposed antenna has a unique advantage in simultaneously measuring two orthogonal magnetic-fields.

An Ultrawideband Differential Magnetic-Field Probe for Near-Field Scanning

In this study, a differential magnetic-field probe capable of measuring two orthogonal magnetic-field components is developed. Different from conventional single-component magnetic-field probes with a detection loop, the proposed probe consists of two orthogonal detection loops and a short-circuit point. Two orthogonal induced loops are used to sense the orthogonal magnetic-field components ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${H} _{y}$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${H} _{x}$ </tex-math></inline-formula> ). In addition, many grounded vias are inserted into the probe to suppress unwanted electromagnetic modes. To prove the design accuracy, the presented probe is simulated, measured, and analyzed. It is observed that the working frequency of the probe is 1 MHz–20 GHz.

An Ultrawideband Multicomponent Differential Magnetic Probe for Near-Field Scanning

In this brief, a novel ultrawideband multi-component differential magnetic probe is proposed. Two pairs of differential loops and connecting vias were used to simultaneously sense two orthogonal magnetic-field components (Hx and Hy). Two rows of via fences next to the loops were used to prevent unwanted electromagnetic modes. The operating frequency band of the proposed probe ranges from the 1 MHz to 20 GHz. The accuracy of the proposed probe is verified by comparing its measurement and simulation results. This significantly improves the near-field scanning efficiency compared with the conventional single-component probe.

Numerical modeling of the co-seismic electromagnetic signals observed during the 2014 Mw 4.9 Hammam Melouane earthquake, Northern Algeria

The seismic activity in northern Algeria provides the opportunity to observe earthquake-related electromagnetic signals through magnetotelluric (MT) measurements. Through an MT station, we measured the two telluric and three orthogonal magnetic field components. On December 23rd, 2014, a moderate earthquake (Mw = 4.9) occurred in the village of Hammam Melouane (Algeria), located 36 km northeast of the MT site. This event allowed the observation of a co-seismic electromagnetic signal in the MT time series. The analysis of the electromagnetic time series using Fourier transform revealed the spectral characteristics of these co-seismic electromagnetic signals with a high spectral amplitude that started at the frequency of 0.3 Hz. Then, we simulate the electric and magnetic responses of the Hammam Melouane earthquake based on the electrokinetic mechanism. We conducted the simulations using a point source model with a realistic layered earth model and compared the synthetic signals to the observed data in the frequency band 0.3–6 Hz. The result shows that the synthetic electric signals match the measured data in both amplitude and waveform for the parts of the recordings after the arrival of the S wave with a phase shift. Similarly, the synthetic magnetic field agrees with the observed data in the waveforms with a phase shift, but their amplitudes are smaller than the observed data. In the latter part of the records (>18 s), a poor disagreement can be seen between the synthetic and observed electromagnetic field signals in their shape and amplitudes. We investigated the rotation-induced magnetic field effect as a possible mechanism for the generation of additional co-seismic magnetic signals. The synthetic magnetic fields resulting from the magnetometer rotation modeling are in agreement with the observed magnetic data in terms of amplitudes after the arrival of seismic waves. The main conclusion of this study reveals that the electrokinetic effect is responsible for the generation of co-seismic electric fields while the rotation of magnetic sensors is likely the main cause of co-seismic magnetic fields.

A new borehole electromagnetic receiver developed for controlled-source electromagnetic methods

Abstract. Conventional surface electromagnetic methods have limitations of a shallow detection depth and low resolution. To increase the detection depth and resolution, borehole–surface electromagnetic methods for electromagnetic three-dimensional observations of the ground, tunnels, and boreholes have been developed. Current borehole receivers only measure a single parameter of the magnetic field component, which does not meet the special requirements of controlled-source electromagnetic (CSEM) methods. This study proposes a borehole electromagnetic receiver that realizes synchronous acquisition of the vertical electric field component in the borehole and the three-axis orthogonal magnetic field components. This receiver uses Ti electrodes and fluxgate magnetometers (fluxgates) as sensors to acquire electric and magnetic field components. Multi-component comprehensive observation methods that add the electric field component can effectively support the CSEM method, improve detection accuracy, and exhibit a strong potential for detecting deep ore bodies. We conducted laboratory and field experiments to verify the performance of our new borehole electromagnetic receiver. The receiver achieved a magnetic field noise of less than 6 pTHz-1/2 at 1 kHz, and the electric field noise floor was approximately 20 nVm-1Hz-1/2 at 1 kHz. The −3 dB electric field bandwidth can reach DC −10 kHz. The results of our experiments prove that high-quality CSEM signals can be obtained using this new borehole electromagnetic receiver and that the electric field component exhibits sufficient advantages for measuring the vertical component of the electric field.

Evaluation of errors in estimating the azimuth of powerful lightning discharges from measurements of Q-burstst

In this work, we study the variability of errors in determining the azimuth of Q-bursts’ sources on a daily time scale. Qbursts are electromagnetic pulse radiation in the extremely low frequency (ELF) range, excited by powerful lightning discharges, and they are used to locate lightnings over the world. We estimated the errors from data collected for two horizontal orthogonal magnetic field components of Q-bursts. Experimental records of Q-bursts were made at Akademik Vernadsky station from March to April 2019, which covers the vernal equinox day. We determined the azimuth of a Q-bursts’ source by digital rotation of the coordinate system until the signal in one magnetic component would drop to its minimum value. The absolute value of the azimuth error was estimated from the ratio of the Q-burst’s amplitude to the standard deviation of the residual signal. With an automated processing procedure, we analyzed over 800 thousand Q-bursts with amplitude over 10 picotesla. A characteristic diurnal pattern has been discovered in the estimated azimuth errors variations. The night level of the azimuth error exceeded the day level by about two degrees on average. The decrease-rise-decrease И-shaped swing during transition from night to day and mirror-symmetric Nshaped swing during transition from day to night were identified. Each of those transitional swings takes about four hours. A comparison of the daily variations in the total intensity of ELF background noise with the estimated daily azimuth error diagrams demonstrates the opposite character: maximal level of the ELF background noise was observed during the daytime while the estimated azimuth errors take minimal values at this time. This contradicts the generally accepted notion that increasing the noise increases the error. Thus, we suppose that the residual magnetic component in a Q-burst occurs not only from the background noise but can also result from nonlinear polarization of the incident wave due to gyrotropy of the nighttime lower ionosphere. Coherent waves resulting from diffraction of the incident field on the day-night interface in the Earth-ionosphere cavity could explain the И- and N-shaped swings of the azimuth error during the passage of the solar terminator.

Quantification of Sq parameters in 2008 based on geomagnetic observatory data

The paper presents an investigation of the time-dependent parameters of the solar quiet daily (Sq) variation for the minimum of the solar cycle 23/24 in 2008. We apply “Measure of Anomalousness” algorithm to detection of the magnetically quiet days. Global distribution of Sq amplitudes of the three orthogonal magnetic field components is analyzed using one-year data from 75 INTERMAGNET geomagnetic observatories and 46 SuperMAG stations. The study reveals strong latitudinal dependence of the Sq(X) amplitudes, which is approximated by the sixth-order polynomial trend curve. Sq(Y) amplitudes also suggest latitudinal dependence, while no significant difference is found in the Sq(Z) amplitudes across all latitudes. In the equatorial region, Sq(X) amplitudes are strongly affected by the equatorial electrojet (EEJ), having maxima during equinoctial seasons in the region of the South Atlantic magnetic anomaly (SAA). Sq(Y) demonstrates clear dependence on solar activity and amount of solar illumination, as the Sq(Y) amplitudes are typically greater in the summer-hemisphere and smaller in the winter-hemisphere. We analyze equivalent Sq current system using observatory data from the Australian mainland and narrow European-African latitudinal segment. Sq current system also strongly depends on solar activity, as the current vortices in the winter-hemisphere disintegrate showing no trace of Sq current loops’ formation, while the current vortices become evident in the summer-hemisphere.

Sensitive and stable vector magnetometer for operation in zero and finite fields.

We report on an optically pumped magnetometer that uses multiple laser beams to pump and probe spin-polarized Cs atoms. The selected sensor geometry allows for operation in finite magnetic fields as well as close to zero field. In finite fields the magnetometer employs free spin precession signals to determine the field modulus and direction as described in a separate publication. This publication focuses on the magnetometer operation close to zero field, which is based on a ground state Hanle resonance. The four laser beams permit the simultaneous measurement of two orthogonal magnetic field components in a differential detection scheme that greatly suppresses technical laser power noise. Sensitivities better than 54 fT/Hz1/2 could be demonstrated simultaneously for both measurement channels in a well shielded environment. A minimum Allan deviation, limited by residual field fluctuations, of better than 40 fT was observed for integration times of 2s. The magnetometer achieves high sensitivity and stability in offset fields as well as close to zero field and is, thus, a universal tool for low frequency magnetic field measurements.

Two-axis silicon Hall effect magnetometer

A novel single-chip sensing device for measurement of two orthogonal magnetic-field components using a common transducer zone and, for the first time, containing four contacts, is presented. On a rectangular n-type silicon substrate, n+-ohmic planar contacts are implemented − two of them are elongated and serve as power supply, and the other two terminals, positioned in the middle of the region between the elongated ones, function as outputs. A proper coupling arrangement is used for obtaining the information about vector components Bx (parallel to the supply contacts) and Bz (perpendicular to the substrate). Actually, the 2D magnetometer integrates an in-plane sensitivе Hall element and a device with vertical magnetic-field activation. The sensor operation is determined by the direction of the individual parts of the curvilinear current trajectory and the Lorentz force deflection action on them. The 2D vector sensor interface circuitry in hybrid realization comprises three instrumentation amplifiers and a differential amplifier. Simple fabrication technology is applied, containing four masks. The effective spatial resolution volume is high, constituting about 90×60×40μm3. The respective channel-magnetosensitivities without amplification reached: the lateral sensitivity Sx≈17V/AT and the vertical sensitivity Sz≈23.3V/AT. The channel cross-talk at induction B≤1.0T is no more than 3% and the lowest detected induction Bmin for the two-axis device at supply 3mA over frequency range f≤100Hz is about 11μT.

Design and analysis of miniature tri-axial fluxgate magnetometer

The detection technology of weak magnetic field is widely used in Earth resource survey and geomagnetic navigation. Useful magnetic field information can be obtained by processing and analyzing the measurement data from magnetic sensors. A miniature tri-axial fluxgate magnetometer is proposed in this paper. This miniature tri-axial fluxgate magnetometer with ring-core structure has a dynamic range of the Earth’s field ±[Formula: see text]65,000 nT, resolution of several nT. It has three independent parts placed in three perpendicular planes for measuring three orthogonal magnetic field components, respectively. A field-programmable gate array (FPGA) is used to generate stimulation signal, analog-to-digital (A/D) convertor control signal, and feedback digital-to-analog (D/A) control signal. Design and analysis details are given to improve the dynamic range, sensitivity, resolution, and linearity. Our prototype was measured and compared with a commercial standard Magson fluxgate magnetometer as a reference. The results show that our miniature fluxgate magnetometer can follow the Magson’s change trend well. When used as a magnetic compass, our prototype only has [Formula: see text] deviation compared with standard magnetic compass.

An FDTD Study of Errors in Magnetic Direction Finding of Lightning Due to the Presence of Conducting Structure Near the Field Measuring Station

Lightning electromagnetic fields in the presence of conducting (grounded) structure having a height of 60 m and a square cross-section of 40 m × 40 m within about 100 m of the observation point are analyzed using the 3D finite-difference time-domain (FDTD) method. Influence of the conducting structure on the two orthogonal components of magnetic field is analyzed, and resultant errors in the estimated lightning azimuth are evaluated. Influences of ground conductivity and lightning current waveshape parameters are also examined. When the azimuth vector passes through the center of conducting structure diagonally (e.g., azimuth angle is 45°) or parallel to its walls (e.g., azimuth angle is 0°), the presence of conducting structure equally influences Hx and Hy, so that Hx/Hy is the same as in the absence of structure. Therefore, no azimuth error occurs in those configurations. When the conducting structure is not located on the azimuth vector, the structure influences Hx and Hy differently, with the resultant direction finding error being greater when the structure is located closer to the observation point.

Temperature and 3D magnetic field measurement using the same sensing zone

A novel functional multisensor for temperature and subsequent measurement of three orthogonal magnetic-field components using the same transducer zone is presented. One central emitter, two symmetrically positioned base contacts and two pairs of output ohmic terminals on a silicon substrate, close to the bases, are implemented. Three subsequent coupling arrangements of the four output terminals use the same sensor region at different times. Temperature is measured through the voltage on the forward biased p+-n emitter junction at a constant supply current. The obtained channel sensitivities are Sx=7V/AT, Sy=9V/AT and Sz=11.3V/AT. The thermo-sensitivity is KEB=−1.82mV/°C at a current of 1mA. Magnetic induction does not perturb thermometric voltage within a wide range, −0.8T≤B≤0.8T. The spatial resolution is high reaching about 110×90×40μm3 and the channel cross-sensitivities are no more than 2.6% at induction B=1.0T. The mean lowest detected magnetic field at a frequency range f≤100Hz and a supply current 3mA is Bmin ≈13μT for the channels.

2D Silicon Magnetometer

A novel single-chip sensing device for measurement of two orthogonal magnetic-field components using one and the same transducer zone is presented. On a rectangular n-type silicon substrate, four n+- ohmic planar contacts are implemented – two of them are elongated and serves as power supply, and other two terminals positioned in the middle of the region between elongated ones, function as outputs only. A proper coupling arrangement is used for obtaining the information about vector components Bx (parallel to the supply contacts) and Bz (perpendicular to the substrate). The sensor operation is determined by the direction of individual parts of the curvilinear current trajectory and the Lorentz force action on them. The 2D magnetometer interface circuitry comprises three instrumentation amplifiers and a differential amplifier. Simple fabrication technology is applied. The effective spatial resolution is high consisting 90 x 60 x 40 μm3. The respective channel-magnetosensitivities without amplification reaches Sx ≈ 17 V/AT and Sz ≈ 23.3 V/AT, the channel cross-talk at induction B ≤ 1.0 T is no more than 3% and lowest detected induction Bmin for the two-axis device at a supply 3 mA over frequency range f ≤ 100 Hz is about 11 μT.

Analysis and Simulation of Flight Effects on an Airborne Magnetic Gradient Tensor Measurement System

A magnetic tensor gradiometer is used to measure the spatial derivatives of three orthogonal magnetic field components. Being relatively insensitive to the geomagnetic field affords it the capability of being loaded onto flying platforms to conduct an airborne geophysical survey. It is especially suitable for exploring shallow buried mines and moving magnetic targets. The aerodynamic model was provided by the open source flight simulator, FlightGear. Estimations of the magnetic gradient tensor model of the magnetic dipole, the magnetic interference model of the aircraft, and the error model of the measuring device were all used to investigate the effects of flight on the airborne magnetic gradient tensor measurement system (AMGTMS). A thorough analysis of its causes, such as the vibration of the aircraft, the different rotating sequences of the coordinate system, and the reasonable sequence of data processing, was also done. The results can be applied to the guide design, integration, calibration, and data processing of the AMGTMS, thus reducing the research and development risk.

Effect of magnetic field inhomogeneity on ion cyclotron motion coherence at high magnetic field.

A three-dimensional code based on the particle-in-cell algorithm modified to account for the inhomogeneity of the magnetic field was applied to determine the effect of Z(1), Z(2), Z(3), Z(4), X, Y, ZX, ZY, XZ(2) YZ(2), XY and X(2)-Y(2) components of an orthogonal magnetic field expansion on ion motion during detection in an FT-ICR cell. Simulations were performed for magnetic field strengths of 4.7, 7, 14.5 and 21 Tesla, including experimentally determined magnetic field spatial distributions for existing 4.7 T and 14.5 T magnets. The effect of magnetic field inhomogeneity on ion cloud stabilization ("ion condensation") at high numbers of ions was investigated by direct simulations of individual ion trajectories. Z(1), Z(2), Z(3) and Z(4) components have the largest effect (especially Z(1)) on ion cloud stability. Higher magnetic field strength and lower m/z demand higher relative magnetic field homogeneity to maintain cloud coherence for a fixed time period. The dependence of mass resolving power upper limit on Z(1) inhomogeneity is evaluated for different magnetic fields and m/z. The results serve to set the homogeneity requirements for various orthogonal magnetic field components (shims) for future FT-ICR magnet design.