scholarly journals Designing a Planar Fluxgate Using the PCB Technology

2021 ◽  
Vol 12 (2) ◽  
pp. 117-123
Author(s):  
A. A. Kolomeitsev ◽  
I. A. Zatonov ◽  
M. I. Pischanskaya ◽  
P. F. Baranov ◽  
D. P. Ilyaschenko ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Microelectromechanical Systems ◽  
Second Harmonic ◽  
Temperature Stability ◽  
Weak Magnetic Fields ◽  
Channel Temperature ◽  
Space Objects ◽  
Low Magnetic Field ◽  
Equipment And Instruments

The development of novel methods, scientific devices and means for measuring magnetic fields generated by ultra-low current is among promising directions in the development of medical equipment and instruments for geodetic surveys and space exploration. The present work is to develop a small sensor capable of detecting weak magnetic fields, which sources are biocurrents, radiation of far space objects and slight fluctuations of the geomagnetic field. Scientists estimate the strength of such magnetic fields as deciles of nanotesla. The key requirements for the sensors of ultra-low magnetic field are: resolution, noise level in the measurement channel, temperature stability, linearity and repeatability of the characteristics from one produced item to another. The aforementioned characteristics can be achieved by using planar technologies and microelectromechanical systems (MEMS) in such advanced sensors.The work describes a complete R&D cycle, from creating the computer model of the sensor under study to manufacturing of a working prototype. To assess the effect of the geometry and material properties, the Jiles–Atherton model is implemented which, unlike the majority of the models used, allows considering the non-linearity of the core, its hysteresis properties and influence of residual magnetization.The dimensions of the developed sensor are 40×20×5 mm, while the technology allows its further diminishment. The sensor has demonstrated the linearity of its properties in the range of magnetic field strength from 0.1 nT to 50 µT for a rms current of excitation of 1.25 mA at a frequency of 30 kHz. The average sensitivity for the second harmonic is 54 µV/nT.

Tuning the Magnetic Alignment of Cellulose Nanocrystals from Perpendicular to Parallel Using Lepidocrocite Nanoparticles

2019 ◽  
Author(s):  
Valentina Guccini ◽  
Sugam Kumar ◽  
Yulia Trushkina ◽  
Gergely Nagy ◽  
Christina Schütz ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Cellulose Nanocrystals ◽  
Small Angle Neutron Scattering ◽  
Lower Amount ◽  
Magnetic Alignment ◽  
Polarized Optical Microscopy ◽  
Parallel Orientation ◽  
Weak Magnetic Fields

The magnetic alignment of cellulose nanocrystals (CNC) and lepidocrocite nanorods (LpN), pristine and in hybrid suspensions has been investigated using contrast-matched small-angle neutron scattering (SANS) under in situ magnetic fields (0 – 6.8 T) and polarized optical microscopy. The pristine CNC (diamagnetic) and pristine LpN (paramagnetic) align perpendicular and parallel to the direction of field, respectively. The alignment of both the nanoparticles in their hybrid suspensions depends on the relative amount of the two components (CNC and LpN) and strength of the applied magnetic field. In the presence of 10 wt% LpN and fields < 1.0 T, the CNC align parallel to the field. In the hybrid containing lower amount of LpN (1 wt%), the ordering of CNC is partially frustrated in all range of magnetic field. At the same time, the LpN shows both perpendicular and parallel orientation, in the presence of CNC. This study highlights that the natural perpendicular ordering of CNC can be switched to parallel by weak magnetic fields and the incorporation of paramagnetic nanoparticle as LpN, as well it gives a method to influence the orientation of LpN.<br>

scholarly journals Sensitivity of PS/CoPd Janus particles to an external magnetic field

RSC Advances ◽  
2021 ◽  
Vol 11 (28) ◽  
pp. 17051-17057
Author(s):  
Anna Eichler-Volf ◽  
Yara Alsaadawi ◽  
Fernando Vazquez Luna ◽  
Qaiser Ali Khan ◽  
Simon Stierle ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Properties ◽  
External Magnetic Field ◽  
Magnetic Fields ◽  
Janus Particles ◽  
Weak Magnetic Fields

PS/CoPd Janus particles respond very sensitively to application of low external magnetic fields. Owing to the magnetic properties, the PS/CoPd particles may be used, for example, to sense the presence of weak magnetic fields as micro-magnetometers.

scholarly journals Magnetized Black Holes: Ionized Keplerian Disks and Acceleration of Ultra-High Energy Particles

Proceedings ◽  
2019 ◽  
Vol 17 (1) ◽  
pp. 13 ◽  
Author(s):  
Zdeněk Stuchlík ◽  
Martin Kološ ◽  
Arman Tursunov
Keyword(s):  
Magnetic Field ◽  
Black Holes ◽  
Magnetic Fields ◽  
High Energy ◽  
Weak Magnetic Fields ◽  
Motion Transformation ◽  
Penrose Process ◽  
Field Lines ◽  
High Energy Particles ◽  
Quasiperiodic Oscillations

Properties of charged particle motion in the field of magnetized black holes (BHs) imply four possible regimes of behavior of ionized Keplerian disks: survival in regular epicyclic motion, transformation into chaotic toroidal state, destruction due to fall into the BHs, destruction due to escape along magnetic field lines (escape to infinity for disks orbiting Kerr BHs). The regime of the epicyclic motion influenced by very weak magnetic fields can be related to the observed high-frequency quasiperiodic oscillations. In the case of very strong magnetic fields particles escaping to infinity could form UHECR due to extremely efficient magnetic Penrose process – protons with energy E > 10 21 eV can be accelerated by supermassive black holes with M ∼ 10 10 M ⊙ immersed in magnetic field with B ∼ 10 4 Gs.

scholarly journals Observations of magnetic fields in Herbig Ae/Be stars

2018 ◽  
Vol 14 (A30) ◽  
pp. 123-123
Author(s):  
Markus Schöller ◽  
Swetlana Hubrig
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
T Tauri Stars ◽  
Be Stars ◽  
T Tauri ◽  
Weak Magnetic Fields ◽  
Order Of Magnitude ◽  
Field Geometry ◽  
Herbig Ae Stars ◽  
Magnetospheric Accretion

AbstractModels of magnetically driven accretion reproduce many observational properties of T Tauri stars. For the more massive Herbig Ae/Be stars, the corresponding picture has been questioned lately, in part driven by the fact that their magnetic fields are typically one order of magnitude weaker. Indeed, the search for magnetic fields in Herbig Ae/Be stars has been quite time consuming, with a detection rate of about 10% (e.g. Alecian et al. 2008), also limited by the current potential to detect weak magnetic fields. Over the last two decades, magnetic fields were found in about twenty objects (Hubrig et al. 2015) and for only two Herbig Ae/Be stars was the magnetic field geometry constrained. Ababakr, Oudmaijer & Vink (2017) studied magnetospheric accretion in 56 Herbig Ae/Be stars and found that the behavior of Herbig Ae stars is similar to T Tauri stars, while Herbig Be stars earlier than B7/B8 are clearly different. The origin of the magnetic fields in Herbig Ae/Be stars is still under debate. Potential scenarios include the concentration of the interstellar magnetic field under magnetic flux conservation, pre-main-sequence dynamos during convective phases, mergers, or common envelope developments. The next step in this line of research will be a dedicated observing campaign to monitor about two dozen HAeBes over their rotation cycle.

scholarly journals Discovery of weak magnetic fields in four DZ white dwarfs in the local 20 pc volume

2019 ◽  
Vol 630 ◽  
pp. A65 ◽  
Author(s):  
S. Bagnulo ◽  
J. D. Landstreet
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
White Dwarfs ◽  
Field Measurements ◽  
Weak Magnetic Fields ◽  
Polluted Atmosphere ◽  
Highly Sensitive ◽  
Cool White Dwarfs ◽  
The Magnetic Field ◽  
Made In

We report the discovery of weak magnetic fields in three white dwarfs within the local 20 pc volume (WD 0816−310, WD 1009−184, and WD 1532+129), and we confirm the magnetic nature of a fourth star (WD 2138−332) in which we had previously detected a field at a 3σ level. The spectra of all these white dwarfs are characterised by the presence of metal lines and lack of H and He lines, that is, they belong to the spectral class DZ. The polarisation signal of the Ca II H+K lines of WD 1009−184 is particularly spectacular, with an amplitude of 20% that is due to the presence of a magnetic field with an average line-of-sight component of 40 kG. We have thus established that at least 40% of the known DZ white dwarfs with an He-rich atmosphere contained in the 20 pc volume have a magnetic field, while further observations are needed to establish whether the remaining DZ white dwarfs in the same volume are magnetic or not. Metal lines in the spectra of DZ white dwarfs are thought to have originated by accretion from rocky debris, and it might be argued that a link exists between metal accretion and higher occurrence of magnetism. However, we are not able to distinguish whether the magnetic field and the presence of a polluted atmosphere have a common origin, or if it is the presence of metal lines that allows us to detect a higher frequency of magnetic fields in cool white dwarfs, which would otherwise have featureless spectra. We argue that the new highly sensitive longitudinal field measurements that we have made in recent years are consistent with the idea that the magnetic field appears more frequently in older than in younger white dwarfs.

Room Temperature Sample Scanning SQUID Microscope for Imaging the Magnetic Fields of Geological Specimens

2013 ◽  
Vol 475-476 ◽  
pp. 3-6 ◽  
Author(s):  
Qing Meng Wang ◽  
Hua Feng Qin ◽  
Qing Song Liu ◽  
Tao Song
Keyword(s):  
Magnetic Field ◽  
Low Temperature ◽  
Magnetic Fields ◽  
Liquid Helium ◽  
Quantum Interference ◽  
Three Dimensional ◽  
Input Circuit ◽  
Pickup Coil ◽  
Weak Magnetic Fields ◽  
Scanning Squid

A microscope to image weak magnetic fields using a low-temperature superconducting quantum interference device (SQUID) had developed with a liquid helium consumption rate of ~0.5L/hour. The gradient pickup coil is made by a low-temperature superconducting niobium wire with a diameter of 66 μm, which is coupled to the input circuit of the SQUID and is then enwound on the sapphire bobbin. Both of the pickup coil and the SQUID sensor are installed in a red copper cold finger, which is thermally anchored to the liquid helium evaporation platform in the vacuum space of the cryostat. To reduce the distance between the pickup coil and sample, a 100 μm thick sapphire window is nestled up to the bottom of the cryostat. A three-dimensional scanning stage platform with a 50 cm Teflon sample rack under the sapphire window had the precision of 10 μm. To test the fidelity of the new facility, the distribution of the magnetic field of basalt slice specimens was determined. Results show that the spatial resolution of the newly-designed facility is 500 μm with a gradient magnetic field sensitivity of 380fT. This opens new opportunities in examining the distribution of magnetic assemblages in samples, which bear great geological and geophysical information.

scholarly journals Searching for a link between the presence of chemical spots on the surface of HgMn stars and their weak magnetic fields

2008 ◽  
Vol 4 (S259) ◽  
pp. 401-402 ◽  
Author(s):  
Igor S. Savanov ◽  
S. Hubrig ◽  
J. F. González ◽  
M. Schöller
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Imaging Technique ◽  
Doppler Imaging ◽  
Magnetic Field Topology ◽  
Weak Magnetic Fields

AbstractWe present the results of mapping the HgMn star AR Aur using the Doppler Imaging technique for several elements and discuss the obtained distributions in the framework of a magnetic field topology.

scholarly journals Effect of magnetic fields on cryptochrome-dependent responses in Arabidopsis thaliana

2009 ◽  
Vol 6 (41) ◽  
pp. 1193-1205 ◽  
Author(s):  
Sue-Re Harris ◽  
Kevin B. Henbest ◽  
Kiminori Maeda ◽  
John R. Pannell ◽  
Christiane R. Timmel ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Arabidopsis Thaliana ◽  
Magnetic Fields ◽  
Low Frequency ◽  
Zero Field ◽  
Experimental Conditions ◽  
Replication Studies ◽  
Weak Magnetic Fields ◽  
Simultaneous Control ◽  
Independent Replication

The scientific literature describing the effects of weak magnetic fields on living systems contains a plethora of contradictory reports, few successful independent replication studies and a dearth of plausible biophysical interaction mechanisms. Most such investigations have been unsystematic, devoid of testable theoretical predictions and, ultimately, unconvincing. A recent study, of magnetic responses in the model plant Arabidopsis thaliana , however, stands out; it has a clear hypothesis—that seedling growth is magnetically sensitive as a result of photoinduced radical-pair reactions in cryptochrome photoreceptors—tested by measuring several cryptochrome-dependent responses, all of which proved to be enhanced in a magnetic field of intensity 500 μT. The potential importance of this study in the debate on putative effects of extremely low-frequency electromagnetic fields on human health prompted us to subject it to the ‘gold standard’ of independent replication. With experimental conditions chosen to match those of the original study, we have measured hypocotyl lengths and anthocyanin accumulation for Arabidopsis seedlings grown in a 500 μT magnetic field, with simultaneous control experiments at 50 μT. Additionally, we have determined hypocotyl lengths of plants grown in 50 μT, 1 mT and approximately 100 mT magnetic fields (with zero-field controls), measured gene ( CHS , HY5 and GST ) expression levels, investigated blue-light intensity effects and explored the influence of sucrose in the growth medium. In no case were consistent, statistically significant magnetic field responses detected.

scholarly journals Магнитоструктурные особенности фазовых переходов в системе Mn-=SUB=-1-x-=/SUB=-Co-=SUB=-x-=/SUB=-NiGe Часть 1. Экспериментальные результаты

2021 ◽  
Vol 63 (12) ◽  
pp. 2073
Author(s):  
В.И. Митюк ◽  
Г.С. Римский ◽  
К.И. Янушкевич ◽  
В.В. Коледов ◽  
А.В. Маширов ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Phase ◽  
Experimental Studies ◽  
Anomalous Behavior ◽  
Magnetic Phase Transitions ◽  
Strong Magnetic Fields ◽  
Weak Magnetic Fields ◽  
Wide Range ◽  
Co Concentrations

Experimental studies of the magnetic and structural properties of solid solutions of the Mn1-xCoxNiGe system in a wide range of Co concentrations (0.05≤ x≤ 0.8), temperatures (5 K≤ x≤600 K) and magnetic fields (0.016 T≤ x≤ 13.5 T) have revealed a number of nontrivial magnetic and magnetocaloric features of this system. The latter include: 1) a change in the nature of magnetic phase transitions from magnetostructural transitions of the 1st order paramagnetism-antiferromagnetism (0.05≤ x≤ 0.15) to isostructural transitions of the 2nd order paramagnetism-ferromagnetism (0.15≤ x≤0.8) with a change in the concentration of Co ; 2) anomalous behavior of low-temperature regions of magnetization in weak magnetic fields; 3) a change in the saturation magnetization and the appearance of irreversible magnetic field-induced transitions at helium temperatures in strong magnetic fields.

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