scholarly journals In-Plane Sensitive Magnetoresistors as a Hall Device

Proceedings ◽  
2018 ◽  
Vol 2 (13) ◽  
pp. 710
Author(s):  
Siya Lozanova ◽  
Ivan Kolev ◽  
Avgust Ivanov ◽  
Chavdar Roumenin
Keyword(s):  
Magnetic Field ◽  
High Performance ◽  
Ohmic Contacts ◽  
Signal To Noise Ratio ◽  
Current Mode ◽  
Constant Current ◽  
Field Polarity ◽  
Practical Applications ◽  
High Measurement ◽  
The Magnetic Field

A novel coupling of a pair of identical two-contact (2C) magnetoresistors transformed into an in-plane sensitive Hall device is presented. The ohmic contacts are cross-linked, also adding a load resistor bridge, providing for constant current mode of operation and eliminating the inevitable parasitic offset. This silicon configuration, apart from its simplified layout, has linear and odd output voltage as a function of the magnetic field and current. The quadratic and even magnetoresistance in the two parts of this innovative device is completely compensated, which ensures high measurement accuracy alongside with identification of the magnetic field polarity. The experimental prototypes feature sensitivity of 110 V/AT. The mean lowest detected magnetic induction B at supply current of 3 mA over frequency range f ≤ 100 Hz at a signal-to-noise ratio equal to unity is Bmin ≈ 10 μT. Тhe high performance and the complete electrical, temperature and technological matching of the parts of this unusual Hall device make it very promising for many practical applications.

scholarly journals Simulation study of the plasma-brake effect

2014 ◽  
Vol 32 (10) ◽  
pp. 1207-1216 ◽  
Author(s):  
P. Janhunen
Keyword(s):  
Magnetic Field ◽  
High Performance ◽  
Ionospheric Plasma ◽  
Low Earth Orbit ◽  
Earth Orbit ◽  
Breaking Force ◽  
Field Orientation ◽  
Particle In Cell ◽  
Leo Satellite ◽  
The Magnetic Field

Abstract. Plasma brake is a thin, negatively biased tether that has been proposed as an efficient concept for deorbiting satellites and debris objects from low Earth orbit. We simulate the interaction with the ionospheric plasma ram flow with the plasma-brake tether by a high-performance electrostatic particle in cell code to evaluate the thrust. The tether is assumed to be perpendicular to the flow. We perform runs for different tether voltage, magnetic-field orientation and plasma-ion mass. We show that a simple analytical thrust formula reproduces most of the simulation results well. The interaction with the tether and the plasma flow is laminar (i.e. smooth and not turbulent) when the magnetic field is perpendicular to the tether and the flow. If the magnetic field is parallel to the tether, the behaviour is unstable and thrust is reduced by a modest factor. The case in which the magnetic field is aligned with the flow can also be unstable, but does not result in notable thrust reduction. We also correct an error in an earlier reference. According to the simulations, the predicted thrust of the plasma brake is large enough to make the method promising for low-Earth-orbit (LEO) satellite deorbiting. As a numerical example, we estimate that a 5 km long plasma-brake tether weighing 0.055 kg could produce 0.43 mN breaking force, which is enough to reduce the orbital altitude of a 260 kg object mass by 100 km over 1 year.

scholarly journals Magnetic properties of cobalt microwires measured by piezoresistive cantilever magnetometry

2014 ◽  
Vol 1 (1) ◽  
Author(s):  
G. Tosolini ◽  
J. M. Michalik ◽  
R. Córdoba ◽  
J. M. de Teresa ◽  
F. Pérez-Murano ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Room Temperature ◽  
Signal To Noise Ratio ◽  
Static Deflection ◽  
Magnetic Structures ◽  
Dual Beam ◽  
Piezoresistive Cantilevers ◽  
Good Signal ◽  
The Magnetic Field

AbstractWe present the magnetic characterization of cobalt wires grown by focused electron beam-induced deposition (FEBID) and studied using static piezoresistive cantilever magnetometry. We have used previously developed high force sensitive submicron-thick silicon piezoresistive cantilevers. High quality polycrystalline cobalt microwires have been grown by FEBID onto the free end of the cantilevers using dual beam equipment. In the presence of an external magnetic field, the magnetic cobalt wires become magnetized, which leads to the magnetic field dependent static deflection of the cantilevers. We show that the piezoresistive signal from the cantilevers, corresponding to a maximum force of about 1 nN, can be measured as a function of the applied magnetic field with a good signal to noise ratio at room temperature. The results highlight the flexibility of the FEBID technique for the growth of magnetic structures on specific substrates, in this case piezoresistive cantilevers.

scholarly journals Practice and perspectives of using ultrasensitive magnetometers in biomedical research.

2021 ◽  
Author(s):  
Yu.V. Maslennikov ◽  
◽  
◽  
Keyword(s):  
Magnetic Field ◽  
Biomedical Research ◽  
Magnetic Measurements ◽  
Signal To Noise Ratio ◽  
Frequency Range ◽  
Optically Pumped ◽  
Technical Solutions ◽  
Further Development ◽  
The Magnetic Field

There are a large number of sensors for measuring the magnetic field of biological objects. They are characterized by the type of the measured physical parameter (magnetic field strength, magnetic flux, etc.), the level of intrinsic sensitivity, and the frequency range of the recorded signals. The long-term practice of studying biomagnetic signals shows that only SQUID-based magnetometers and optically pumped magnetometers have sensitivity levels sufficient for recording biomagnetic signals with the required signal-to-noise ratio. This chapter reflects the main directions of using such magnetometers and methods of magnetic measurements in biomedical research, gives examples of existing technical solutions, and shows possible ways of their further development.

scholarly journals The Effect of Magnetic Field Strength and Geometry on the Deposition Rate and Ionized Flux Fraction in the HiPIMS Discharge

Plasma ◽  
2019 ◽  
Vol 2 (2) ◽  
pp. 201-221 ◽  
Author(s):  
Hamidreza Hajihoseini ◽  
Martin Čada ◽  
Zdenek Hubička ◽  
Selen Ünaldi ◽  
Michael A. Raadu ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Deposition Rate ◽  
Average Power ◽  
Current Mode ◽  
Ionization Probability ◽  
Cathode Voltage ◽  
Peak Current ◽  
Voltage Mode ◽  
Operating Modes ◽  
The Magnetic Field

We explored the effect of magnetic field strength | B | and geometry (degree of balancing) on the deposition rate and ionized flux fraction F flux in dc magnetron sputtering (dcMS) and high power impulse magnetron sputtering (HiPIMS) when depositing titanium. The HiPIMS discharge was run in two different operating modes. The first one we refer to as “fixed voltage mode” where the cathode voltage was kept fixed at 625 V while the pulse repetition frequency was varied to achieve the desired time average power (300 W). The second mode we refer to as “fixed peak current mode” and was carried out by adjusting the cathode voltage to maintain a fixed peak discharge current and by varying the frequency to achieve the same average power. Our results show that the dcMS deposition rate was weakly sensitive to variations in the magnetic field while the deposition rate during HiPIMS operated in fixed voltage mode changed from 30% to 90% of the dcMS deposition rate as | B | decreased. In contrast, when operating the HiPIMS discharge in fixed peak current mode, the deposition rate increased only slightly with decreasing | B | . In fixed voltage mode, for weaker | B | , the higher was the deposition rate, the lower was the F flux . In the fixed peak current mode, both deposition rate and F flux increased with decreasing | B | . Deposition rate uniformity measurements illustrated that the dcMS deposition uniformity was rather insensitive to changes in | B | while both HiPIMS operating modes were highly sensitive. The HiPIMS deposition rate uniformity could be 10% lower or up to 10% higher than the dcMS deposition rate uniformity depending on | B | and in particular the magnetic field topology. We related the measured quantities, the deposition rate and ionized flux fraction, to the ionization probability α t and the back attraction probability of the sputtered species β t . We showed that the fraction of the ions of the sputtered material that escape back attraction increased by 30% when | B | was reduced during operation in fixed peak current mode while the ionization probability of the sputtered species increased with increasing | B | , due to increased discharge current, when operating in fixed voltage mode.

INFLUENCE OF THE MAGNETIC FIELD ON THE TRANSVERSE RUNAWAY THRESHOLD

2007 ◽  
Vol 21 (10) ◽  
pp. 1715-1720 ◽  
Author(s):  
NANA METREVELI ◽  
ZAUR KACHLISHVILI ◽  
BEKA BOCHORISHVILI
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Electric Fields ◽  
Applied Electric Field ◽  
Nonlinear Oscillations ◽  
Hot Electrons ◽  
Total Field ◽  
Practical Applications ◽  
Energy And Momentum ◽  
The Magnetic Field

The transverse runaway (TR) is a phenomenon whereby for a certain combination of energy and momentum scattering mechanisms of hot electrons, and for a certain threshold of the applied electric field, the internal (total) field tends to infinity. In this work, the effect of the magnetic field on the transverse runaway threshold is considered. It is shown that with increasing magnetic field, the applied critical electric fields relevant to TR decrease. The obtained results are important for practical applications of the TR effect as well as for the investigation of possible nonlinear oscillations that may occur near the TR threshold.

Magnetic Generator with Automatic Gain Regulation in a Wireless Tracking System for a Capsule Endoscope

2013 ◽  
Vol 401-403 ◽  
pp. 1393-1396
Author(s):  
Xu Dong Guo ◽  
Chao Ruan ◽  
Bin Ge ◽  
Rong Guo Yan ◽  
Ying Liu
Keyword(s):  
Magnetic Field ◽  
Signal To Noise Ratio ◽  
Tracking System ◽  
Reference Value ◽  
Digital Signal ◽  
Measuring Method ◽  
Magnetic Sensor ◽  
Capsule Endoscope ◽  
The Magnetic Field ◽  
Magnetic Generator

To track a capsule endoscope, a novel measuring method based on alternating magnetic field is presented. The signal-to-noise ratio of the magnetic sensor decreases sharply with the increasing tracking distance. Thus, a magnetic generator with automatic gain regulation is designed to improve the localization precision. It is composed of a microcontroller, a DA converter, a timer, a waveform synthesis circuit, a power amplifier, a sequence control circuit and excitation coils. First, the wireless magnetic sensor measures the strength of the magnetic field produced by the magnetic generator. Via radio frequency communication, the measured result is feedback to the comparator of the microcontroller. According to a deviation obtained by comparing the measured results with the reference value, the microcontroller outputs a digital signal to the DA converter to control the magnitude of the exciting current. The prototype of the system was developed and the experiment was performed. The experiment shows that the magnetic field generator can automatically adjust the strength of the exciting signal.

scholarly journals The Magnetic Fields in the Envelopes of Proto-Planetary Nebulae

1993 ◽  
Vol 155 ◽  
pp. 381-381 ◽  
Author(s):  
J.Y. Hu
Keyword(s):  
Magnetic Field ◽  
High Frequency ◽  
Signal To Noise Ratio ◽  
Planetary Nebulae ◽  
Frequency Resolution ◽  
High Signal ◽  
Max Planck ◽  
Molecular Line ◽  
Protoplanetary Nebulae ◽  
The Magnetic Field

It is possible that the magnetic field plays important role in the formation of planetary nebulae(Poscoli, 1992). In order to measure the strength of magnetic field in the envelope of protoplanetary nebulae(PPNe) we have used the Max-Planck-Institut fur Radioastronomie 100-m telescope at Effelsberg to obtain the high frequency resolution and high signal-to-noise ratio 1612 MHz spectra of PPNe, IRAS08005-2356, 18276-1431, and 20406+2953 in both circular polarization. The nature of PPN of these objects are confirmed by Slikhuis et al.(1991), Le Bertre(1987), and Hu et al.(1992) based on the extensive optical, infrared and radio molecular line observations.

Observation of Single Magnetic-Flux Quanta Using Electron Holography

1990 ◽  
Vol 48 (1) ◽  
pp. 210-211
Author(s):  
T. Matsuda ◽  
S. Hasegawa ◽  
J. Endo ◽  
N. Osakabe ◽  
A. Tonomura ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Tungsten Wire ◽  
Thin Filament ◽  
Phase Distribution ◽  
Electron Holography ◽  
Practical Applications ◽  
Magnetic Flux Quantum ◽  
Lead Film ◽  
The Magnetic Field

A Magnetic flux quantum (fluxon) penetrating a superconductor plays an important role in both fundamental and practical applications of superconductivity. However, the fluxon has evaded direct observation, because it is shaped like an extremely thin filament in addition to its small flux value, h/2e (=2x10−15Wb). Several methods have already been developed to indirectly observe each filament of flux. One method is Bitter's [1], in which magnetic powder is sprinkled on the superconductor surface. The powder accumulates at the fluxons, and the image is observed by electron microscopy.We have observed the magnetic field of a single fluxon using holographic electron interferometry [2], in which the phase distribution of an electron beam can be measured to a precision of 2Π/50. The schematic diagram of the experiment is shown in Fig. 1. A weak magnetic field is applied perpendicularly to a superconducting lead film. Fiuxons penetrating the film are observed as phase contour fringes through the electron holography process. The sample is prepared by evaporating lead on one side of a thin tungsten wire, which is shown in Fig. 2.

A new furnace for improving thermal demagnetization in paleomagnetism

2020 ◽  
Author(s):  
Huafeng Qin ◽  
Xiang Zhao ◽  
Shuangchi Liu ◽  
Greig Paterson ◽  
Zhaoxia Jiang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Curie Temperature ◽  
High Performance ◽  
Thermal Treatments ◽  
Thermal Demagnetization ◽  
Heating Wire ◽  
Low Magnetic Field ◽  
Detrimental Impact ◽  
The Magnetic Field ◽  
The Ideal

<p>Thermal demagnetization furnaces are routine facilities for paleomagnetic studies. The ideal thermal demagnetizer should maintain “zero” magnetic field during thermal treatments. However, magnetic field noises, including residual magnetic fields of material and induced fields caused by the heating current in the furnace are always present. The key to making high-performance demagnetization furnace is to reduce the magnetic field noises. By combining efficient demagnetization of shielding and a new structure of heating wire, we have developed a new demagnetization furnace with low magnetic field noises. Repeated progressive thermal demagnetization experiments using specimens that were previously completely thermal demagnetized above their Curie temperature were carry out to explore the effects of field within various types of furnace during demagnetization. These experiment confirm that magnetic field noises in the furnace can have an observable and detrimental impact on demagnetization behavior. Comparison between commercial furnaces and our new design show a notable reduction in the impacts of on thermal demagnetization behavior. The new heating element design and procedure for reducing magnetic field noises represent a significant improvement in the design of thermal demagnetizers and allows for extremely weak specimens to be successfully measured.</p>

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