Design Of Magnetometer Research Articles

A high-sensitivity scanning magnetometer based on the giant magneto-impedance effect for measuring local magnetic fields of corrosion currents

The design, main characteristics, and specific features of a new high-sensitivity magnetometer based on the giant magneto-impedance (GMI) effect in amorphous ferromagnetic microwires are considered. It is shown that, in addition to measuring homogeneous fields, the device is capable of detecting weak local magnetic fields of conduction currents and ion currents involved in corrosion processes. Results of in situ magnetic measurements of corrosion processes in the model system of copper–zinc in a sulfuric acid solution qualitatively agree with the data of direct corrosion tests employing the standard gravimetric method.

Construction of an AMR magnetometer for car detection experiments

A new construction of magnetometer with commercially available AMR (anisotropic magnetoresistive) sensors intended for vehicle detection experiments is presented. Initial experiments with simple AMR gradiometer indicated viability of the approach in a real- world setup. For further experiments and acquisition of representative data, a new design of precise multi-channel magnetometer was developed. The design supports two models of commercial AMR sensors: the proven and reliable, but obsolete Honeywell HMC1021-series sensors and newly available Sensitec AFF755B sensors. In the comparison the two types are similar in most achieved parameters, except offset stability in flipped operation regime. Unfortunately, the new AFF755B sensors seem to have perhaps inferior coupling of the flipping (set/reset) coil to the ferromagnetic core that causes insufficient saturation of the AMR material. The issue is being solved by Sensitec, current deliverables of the AFF755B have “product sample” status (September 2015).

Design of Magnetometer Based on GMI Effect in Fe-based Nano-crystalline Ribbon

基于巨磁阻抗效应(GMI)的磁强计是近年来磁强计研究领域的热点. 相比其他类型磁强计, GMI磁强计具有微型化、高灵敏度、快速响应、高温度 稳定性和低功耗的优点. 本文以铁基纳米晶带材为敏感材料, 设计并实现了GMI 磁强计传感器与后续信号处理电路, 组成一台GMI磁强计. 实验结果表明, 该磁 强计在-25000~25000nT量程内灵敏度为0.176mV·nT^-1, 满足实际弱磁场测量要求, 并且具有体积小及功耗低的特点, 有望应用于空间 探测等磁测量领域.

High-sensitivity dc field magnetometer using nonlinear resonance magnetoelectric effect

The design and operation principle of dc field magnetometer using nonlinear resonance magnetoelectric effect in a ferromagnetic–piezoelectric structure are described. It is shown that under action of ac pumping magnetic field the structure generates the output voltage containing higher harmonics whose amplitudes depend on the dc magnetic field. Best performance of the device is obtained if the signal of the third harmonics is used for the dc field measurement. The sensitivity can be considerably (by approximately three orders of magnitude) increased if advantage is taken of the acoustic resonance of the structure at this frequency. There exists the optimal pumping field ensuring the highest sensitivity. Further increasing of this field expands the range of measurable dc fields at the expense of deteriorated sensitivity. The magnetometer fabricated on the basis of a planar langatate-Metglas structure had sensitivity up to ~1V/Oe and allowed detection of the fields as low as ~10−5Oe.

Design of Induction Magnetometer Receiving Sensor for Through-the-Earth Communications

A narrowband, high sensitivity, and low-power consumption induction magnetometer (IM) receiving sensor is designed, built, and tested for through-the-Earth (TTE) communications in this paper. The optimization method is described mathematically and applied for building an IM (central frequency 3180 Hz and 3-dB bandwidth 200 Hz). In this paper, we move the resonant frequency of the coils to the central frequency and optimize the parameters of the IM to minimize the equivalent input magnetic noise level to 7 fT/√Hz within 3-dB bandwidth. The IM dimensions are Φ 40 mm × 350 mm and the power consumption is <;4.2 mW. The feathers of the IM make it a portable receiving sensor for TTE communications.

Design of the Magnetoresistive Magnetometer for ESA’s SOSMAG Project

A prototype of a Service Oriented Spacecraft Magnetometer (SOSMAG) is being developed for European Space Agency’s Space Situational Awareness program, which shall serve as a ready-to-use space weather monitoring system to be mounted on a variety of different spacecraft built without a magnetic cleanliness program. The separation between the natural magnetic field in space and the artificial magnetic field generated by the spacecraft is one of the key issues for its successful performance. The SOSMAG design is based on two types of magnetic sensors. One or two low-noise fluxgate sensors for the required high measurement accuracy will be mounted along a boom of length 1 m, and two anisotropic magnetoresistance (AMR)-based sensors will be used within the spacecraft for detection and characterization of its magnetic disturbances. This paper presents the design and performance of the AMR magnetometer that contains an application-specified integrated circuit (ASIC) and a hybrid sensor as core elements. The magnetometer front-end ASIC, originally developed for National Aeronautics and Space Administration’s Magnetospheric Multiscale mission, is based on a fourth-order sigma–delta A/D converter design. All the active electronics needed for the readout of the AMR sensor and its digitization, as well as for digitizing the magnetometer’s housekeeping data are part of the ASIC. Each of the three-axis hybrid sensors consists of a ceramics circuit board with three HMC1021 sensor elements, one bypass capacitor, a temperature sensor, and a MOSFET driver mounted in chip-on-board technology. A novel approach is used to set and reset the AMR elements. It is done in a narrow-pulsed way at 32 kHz with a pulsewidth of only 238 ns, thus minimizing the required excitation power to 30 mW in total.

Design of Ring Core Fluxgate Magnetometer as Attitude Control Sensor for Low and High Orbit Satellites

We have designed a fluxgate magnetometer which utilizes the detection of ultra-low DC fields down to (even less) 3 nT. In addition to high sensitivity, it also has quite a large dynamical measurement range. The second harmonic voltage used as the sensor signal shows linear dependence on the applied field up to 1 Oe. We report some critical factors affecting the noise level and sensitivity of magnetometer. The core diameter and magnetic properties are some of them. We will report optimal core dimensions resulting in minimal electrical noise. During experiments, we have recognized that ring-shaped six-layered ribbon core must be well attached to the template, since otherwise, it may vibrate on its original position as a function of the excitation frequency. Thus, additional electrical noises become unavoidable.

A Novel Design of Fluxgate Magnetometer: An Insect like Configuration

In the present work, we propose a novel design of the fluxgate magnetometer which utilizes the detection of ultra-low DC fields down to (even less) 10 μOe. Measurement point has four eyes, like insects, with the diameter of each having 100 μm. It means that the magnetometer can be used for the magnetization analysis of local areas as low as 8,000 μ m 2. Sensing elements used in the sensor are in the form of metallic glass with high relative permeability (∼10,000) and low coercive field (<1 Oe). In addition to high sensitivity, it also has quite a large dynamical measurement range. The 2 nd harmonic voltage used as the sensor signal shows linear dependence on the applied field till almost 0.4 Oe. Such a large dynamical range facilitates its use in spacecraft applications, mine detection, earth skills, etc.

Operation of Lorentz-Force MEMS Magnetometers With a Frequency Offset Between Driving Current and Mechanical Resonance

The paper discusses the operation of Lorentz-force-based microelectromechanical magnetometers at a driving-current frequency slightly lower than the device resonance frequency. Among the advantages with respect to operation at resonance, there are a higher achievable signal to noise ratio (thanks to the lower permitted pressure and damping coefficient, which have now no influence on the maximum sensing bandwidth) and the possibility of driving more magnetometers in series through a single current source, enabling the fabrication of low-power 3-axis magnetic field sensors. A partial drawback is represented by a loss in gain-factor. Experimental results obtained on a sample device confirm the trade-off between gain-factor decrease and bandwidth increase. Guidelines for an optimized design of Lorentz force magnetometers are given together with a comparison with other state-of-the-art technologies through the introduction of a figure of merit. In particular, it is shown how Lorentz force devices can reach better performance in terms of minimum detectable magnetic flux density per unit current consumption and bandwidth.

Design and Fabrication of Directly-Coupled HTS-SQUID Magnetometer With a Multi-Turn Input Coil

To improve the field resolution of a magnetometer for use in the Earth's field, we have developed a new magnetometer using a hybrid superconducting quantum interference device (SQUID). A multi-turn input coil (N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i</sub> turns) is inserted between a directly-coupled SQUID and a pickup coil in series in the hybrid SQUID. Screening current couples with the SQUID by both direct current injection and magnetic coupling. To avoid flux trapping, which occurs during cooling in the Earth's field, the width of the SQUID is restricted to be 5 μm. Therefore, the input coil is not stacked on the SQUID inductor like a conventional integrated SQUID but formed around the SQUID. There is an optimal N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i</sub> as a result of the trade-off relationship between the increase of the coupling strength and the decrease of the screening current with increasing N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i</sub> . The magnetometer using the hybrid SQUID with a slit hole inductor showed an effective area of 0.45 mm>; <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> at the optimal N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i</sub> of 3. The magnetic coupling was enhanced by using a square hole inductor that had a larger flux capturing area. The obtained A <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">eff</sub> (~ 0.6 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) was almost doubled from that of the conventional directly coupled magnetometer, resulting in a field noise as low as 18 fT/Hz <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/2</sup> (white).

The Design and Implementation of Tri-Axial Magnetometer

The design, implementation, and testing of a tri-axial magnetometer instrument are introduced. The design is based on the MAG3110 chip. This chip has the properties of low power consumption and high resolution in the conventional mode. It runs with the peak power at 86.4μJ and the resolution of 0.1μT. The 12C5A60S2 MCU is chose as the data process and transfer unit. The data from the MCU is received by the principal computer through serial port. The measurement results, including the strength and the three component of magnetic field are displayed on PC by real-time curve through a VB programmed interface. The comparison between the measurements and the theoretical values shows that this instrument has the characteristic of high accuracy, high sensitivity and real-time display.

A Study of Tri-Axial Fluxgate Magnetometer

This paper is devoted to study tri-axial fluxgate magnetometer, and it begin with principle of fluxgate magnetometer, and then its structure, electric design and test result analysis are introduced. At present, its development tendency is to simplify and miniaturize, we carried out study of tri-axial fluxgate magnetometer. Its technical specifications such as resolution, noise, response of step up, setting up time and sensitivity meet or even better than original design requirements. At first design of tri-axial fluxgate magnetometer is determined and a transducer is developed. Secondly, a high temperature circuit is developed with SOI (Silicon on Insulator) electronics wafer and hybrid circuit technology. At last, 5 specifications test results are presented from aspects of high temperature and high accuracies, respectively.

Laser pumping Cs atom magnetometer of theory research based on gradient tensor measuring

At present, due to space exploration, military technology, geological exploration, magnetic navigation, medical diagnosis and biological magnetic fields study of the needs of research and development, the magnetometer is given strong driving force. In this paper, it will discuss the theoretical analysis and system design of laser pumping cesium magnetometer, cesium atomic energy level formed hyperfine structure with the I-J coupling, the hyperfine structure has been further split into Zeeman sublevels for the effects of magnetic field. To use laser pump and RF magnetic field make electrons transition in the hyperfine structure to produce the results of magneto-optical double resonance, and ultimately through the resonant frequency will be able to achieve accurate value of the external magnetic field. On this basis, we further have a discussion about magnetic gradient tensor measuring method. To a large extent, it increases the magnetic field measurement of information.

Geometrical analysis of planar coil design for fluxgate magnetometer

This paper presents geometrical analysis on the design of planar coupled coils for use as magnetic sensors. Inductance and magnetic coupling of the coil are analyzed using field solver analyzer ASITIC. Effects of different coil parameters, such as winding number, spacing, and width are discussed in detail. As results, the coil design considers not only the inductance value and the height of magnetic coupling, but also the geometrical area consumed. The analysis is verified by experimental data from coupled coil fabricated using surface micromachining techniques. An outer coil area having a typical dimension of 1.8 × 1.8 mm2 and a fix inner coil diameter of 500 μm was fabricated. Coupling factor of about 0.7 and self inductance of 12.7 nH were achieved, which show a reasonably good agreement with the simulated results. The coil platform developed offers an integrated solution for the design of fluxgate magnetometer.

Integration of the electronics and batteries inside the hollow core of a search coil

A novel design of a miniature search coil magnetometer is proposed based on the integration of the electronics and batteries within the hollow core of the search coil. In contrast with conventional designs, where the search coil and its electronics have individual housings and electrostatic shields, this paper presents a design in which the core of the search coil serves both as the housing and the magnetic shield for the electronics and batteries. Moreover, the electrostatic shield of the search coil also shields the electronics and batteries. We found that a thin-wall tube core with sufficient permeability is able to replace a solid rod core without decreasing the average flux sensed by the coil winding. In addition, the outer diameter of the tube core can be increased beyond its optimum size to provide more space for the electronics and batteries without considerably affecting the search coil resolution. To validate the effectiveness of this new design, a miniature search coil magnetometer was built and tested for very low frequencies and ultra-low power consumption.

Design and Analyses of a MEMS Based Resonant Magnetometer

A novel design of a MEMS torsional resonant magnetometer based on Lorentz force is presented and fabricated. The magnetometer consists of a silicon resonator, torsional beam, excitation coil, capacitance plates and glass substrate. Working in a resonant condition, the sensor’s vibration amplitude is converted into the sensing capacitance change, which reflects the outside magnetic flux-density. Based on the simulation, the key structure parameters are optimized and the air damping effect is estimated. The test results of the prototype are in accordance with the simulation results of the designed model. The resolution of the magnetometer can reach 30 nT. The test results indicate its sensitivity of more than 400 mV/μT when operating in a 10 Pa vacuum environment.

The Design of a MEMS Surface Resonant Magnetometer

In this paper, a MEMS surface resonant magnetometer based on Lorentz force is presented. This magnetometer has three current carriers to sense the magnetic field and changes into deflection of beams which will be detected by the comb-capacitance. The alternating current carried by oscillate beams has the same frequency as resonant frequency of the magnetometer structure to make the deflection magnified Q (Quality-factor) times, therefore, it becomes more easily to measure. In this paper, the mechanical model of the sensitive element is established. The equations of stiffness of the system, deflection, first-order resonance frequency and sensitivity are setup and simulated in ANSYS, as well as second-order to fourth-order modal, and harmonic excitation response simulation. It can be seen that the simulation results are in good accordance with the theoretical calculations, which proves the feasibility and the rationality of the theoretical model. The dimensions of the structure are designed, as well as the processing sequence Anodic Silicon-Glass Bonding and Silicon DRIE Multi-user Bulk Micromachining Process which will be used to manufacture the magnetometer. The MEMS surface resonant magnetometer has a high sensitivity, simple structure and easy to manufacture. The prototype sensors are being manufactured in NEDI now.

Design of a double core linear magnetometer based on asymmetric magnetoimpedance effect in nanostructured Finemet ribbons

Abstract The techniques used to produce magnetic sensors encompass many aspects of physics and electronics and are going to develop with each passing year. In this paper, we introduce a double core giant magnetoimpedance sensor. The sensing elements are provided by heat treating the FeCuNbSiB (Finemet) ribbons at 560 °C for 1 h to achieve a high magnetic permeability associated with the nanostructured state. Sensor cores are exposed to a dc current bias in order to provide asymmetric giant magnetoimpedance (AGMI) behavior. The sensor detects both direction and amplitude of the magnetic field with a sensibility of 2 mV/Oe.

Optimization of SQUID magnetometers and gradiometers for magnetic-field-fluctuation thermometers

We report on the design and optimization of SQUID magnetometers and gradiometers intended for use in compact Magnetic-Field-Fluctuation Thermometers (MFFTs). The MFFT is a novel implementation of a noise thermometer, in which the thermally driven Johnson noise currents are detected by measuring the corresponding fluctuations of the magnetic field. This inductive readout can be realized by means of a classical wire-wound pick-up coil connected to a SQUID current sensor or by using single-chip SQUID magnetometers or gradiometers. In either case the pick-up coil should be as close as possible to the surface of the metallic temperature sensor in order to maximize amplitude and bandwidth of the spectral density of the flux noise. However, the spectral density depends on the geometries of pick-up coil and temperature sensor as well. Here we discuss the particular case of planar magnetometers and gradiometers. By solving the forward problem for an infinite slab we are able to calculate the spectral density of the flux noise in pick-up coils of arbitrary shape. The model is then applied to identify the optimal gradiometer configuration to be used in the MFFT. Finally, we compare calculations of this simple model with experimental data obtained in real setups. A MFFT containing such an optimized SQUID gradiometer was successfully operated down to 7 mK even without a superconducting magnetic shielding.

Miniaturized digital fluxgate magnetometer for small spacecraft applications

A novel design of an Earth field digital fluxgate magnetometer is presented, the small magnetometer in low-mass experiment (SMILE). The combination of a number of new techniques results in significant miniaturization of both sensor and electronics. The design uses a sensor with volume compensation, combining three dual rod cores in a Macor® cube with the side dimension of 20 mm. Use of volume compensation provides high geometrical stability of the axes and improved performance compared to component compensated sensors. The sensor is operated at an excitation frequency of 8 kHz. Most of the instrument functionality is combined in a digital signal processing core, implemented in a field programmable gate array (FPGA). The pick-up signal is digitized after amplification and filtering, and values of compensation currents for each of the axes are determined by a digital correlation algorithm, equivalent to a matched filter, and are fed to a hybrid pulse-width modulation/delta-sigma digital-to-analogue converter driving the currents through the compensation coils. Using digital design makes the instrument very flexible, reduces power consumption and opens possibilities for the customization of the operation modes. The current implementation of the design is based on commercial off-the-shelf components. A calibration of the SMILE instrument was carried out at the Nurmijärvi Geophysical Observatory, showing high linearity (within 6 nT on the whole ±50 µT scale), good orthogonality (22 arcmin) and very good temperature stability of the axes.