scholarly journals Multi-axis integrated Hall magnetic sensors

2007 ◽  
Vol 22 (2) ◽  
pp. 20-28 ◽  
Author(s):  
Radivoje Popovic ◽  
Pavel Kejik ◽  
Serge Reymond ◽  
Dragana Popovic ◽  
Marjan Blagojevic ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Flux ◽  
Field Component ◽  
Angular Position ◽  
Magnetic Sensors ◽  
Magnetic Field Component ◽  
The Magnetic Field

Conventional Hall magnetic sensors respond only to the magnetic field component perpendicular to the surface of the sensor die. Multi-axis sensing capability can be provided in the following two ways: (a) by integrating magnetic flux concentrators on the die, and (b) by using vertical Hall devices. Here we review the most important two-and three-axis integrated Hall magnetic sensors based on these concepts. Their applications include mapping of magnetic fields and sensing angular position.

scholarly journals Magnetic fields in massive spirals: The role of feedback and initial conditions

2018 ◽  
Vol 619 ◽  
pp. L5 ◽  
Author(s):  
Evangelia Ntormousi
Keyword(s):  
Magnetic Field ◽  
Velocity Field ◽  
Magnetic Fields ◽  
Field Component ◽  
Initial Conditions ◽  
Magnetic Field Component ◽  
Stellar Feedback ◽  
Random Magnetic Field ◽  
Supernova Feedback ◽  
The Magnetic Field

Context. Magnetic fields play a very important role in the evolution of galaxies through their direct impact on star formation and stellar feedback-induced turbulence. However, their co-evolution with these processes has still not been thoroughly investigated, and the possible effect of the initial conditions is largely unknown. Aims. This Letter presents the first results from a series of high-resolution numerical models, aimed at deciphering the effect of the initial conditions and of stellar feedback on the evolution of the galactic magnetic field in isolated Milky Way-like galaxies. Methods. The models start with an ordered magnetic field of varying strength, either poloidal or toroidal, and are evolved with and without supernova feedback. They include a dark matter halo, a stellar and a gaseous disk, as well as the appropriate cooling and heating processes for the interstellar medium. Results. Independently of the initial conditions, the galaxies develop a turbulent velocity field and a random magnetic field component in under 15 Myr. Supernova feedback is extremely efficient in building a random magnetic field component up to large galactic heights. However, a random magnetic field emerges even in runs without feedback, which points to an inherent instability of the ordered component. Conclusions. Supernova feedback greatly affects the velocity field of the galaxy up to large galactic heights, and helps restructure the magnetic field up to 10 kpc above the disk, independently of the initial magnetic field morphology. On the other hand, the initial morphology of the magnetic field can accelerate the development of a random component at large heights. These effects have important implications for the study of the magnetic field evolution in galaxy simulations.

scholarly journals Observations of Magnetic Fields in Quiescent Prominences

1971 ◽  
Vol 43 ◽  
pp. 192-200 ◽  
Author(s):  
Einar Tandberg-Hanssen
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Field Component ◽  
Zeeman Effect ◽  
Mean Value ◽  
Longitudinal Component ◽  
The Other ◽  
Magnetic Field Component ◽  
The Magnetic Field

The longitudinal component of the magnetic field, B∥, has been recorded in about 135 quiescent prominences observed at Climax during the period 1968–1969. The measurements were obtained with the magnetograph which records the Zeeman effect on hydrogen, helium and metal lines. The following lines were used, Hα; He I, D3, He I, 4471 Å; Na I, D1 and D2, and the observed magnetic field component in these prominences was independent of the line. The overall mean value of the field B∥ for all the prominences was 7.3G. As a rule, the magnetic field enters the prominence on one side and exits on the other, but in traversing the prominence material, the field tends to run along the long axis of the prominence.

Emergence of Twisted Magnetic Flux Related Sigmoidal Brightening

2000 ◽  
Vol 179 ◽  
pp. 263-264
Author(s):  
K. Sundara Raman ◽  
K. B. Ramesh ◽  
R. Selvendran ◽  
P. S. M. Aleem ◽  
K. M. Hiremath
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Flux ◽  
Ultra Violet ◽  
Active Regions ◽  
Morphological Properties ◽  
Energy Storage And Conversion ◽  
The Sun ◽  
X Rays ◽  
The Magnetic Field

Extended AbstractWe have examined the morphological properties of a sigmoid associated with an SXR (soft X-ray) flare. The sigmoid is cospatial with the EUV (extreme ultra violet) images and in the optical part lies along an S-shaped Hαfilament. The photoheliogram shows flux emergence within an existingδtype sunspot which has caused the rotation of the umbrae giving rise to the sigmoidal brightening.It is now widely accepted that flares derive their energy from the magnetic fields of the active regions and coronal levels are considered to be the flare sites. But still a satisfactory understanding of the flare processes has not been achieved because of the difficulties encountered to predict and estimate the probability of flare eruptions. The convection flows and vortices below the photosphere transport and concentrate magnetic field, which subsequently appear as active regions in the photosphere (Rust & Kumar 1994 and the references therein). Successive emergence of magnetic flux, twist the field, creating flare productive magnetic shear and has been studied by many authors (Sundara Ramanet al.1998 and the references therein). Hence, it is considered that the flare is powered by the energy stored in the twisted magnetic flux tubes (Kurokawa 1996 and the references therein). Rust & Kumar (1996) named the S-shaped bright coronal loops that appear in soft X-rays as ‘Sigmoids’ and concluded that this S-shaped distortion is due to the twist developed in the magnetic field lines. These transient sigmoidal features tell a great deal about unstable coronal magnetic fields, as these regions are more likely to be eruptive (Canfieldet al.1999). As the magnetic fields of the active regions are deep rooted in the Sun, the twist developed in the subphotospheric flux tube penetrates the photosphere and extends in to the corona. Thus, it is essentially favourable for the subphotospheric twist to unwind the twist and transmit it through the photosphere to the corona. Therefore, it becomes essential to make complete observational descriptions of a flare from the magnetic field changes that are taking place in different atmospheric levels of the Sun, to pin down the energy storage and conversion process that trigger the flare phenomena.

FINITE ENERGY ONE-HALF MONOPOLE SOLUTIONS

2012 ◽  
Vol 27 (40) ◽  
pp. 1250233 ◽  
Author(s):  
ROSY TEH ◽  
BAN-LOONG NG ◽  
KHAI-MING WONG
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Flux ◽  
Topological Charge ◽  
Magnetic Monopole ◽  
Magnetic Charge ◽  
Finite Energy ◽  
Spatial Infinity ◽  
Yang Mills ◽  
The Magnetic Field

We present finite energy SU(2) Yang–Mills–Higgs particles of one-half topological charge. The magnetic fields of these solutions at spatial infinity correspond to the magnetic field of a positive one-half magnetic monopole at the origin and a semi-infinite Dirac string on one-half of the z-axis carrying a magnetic flux of [Formula: see text] going into the origin. Hence the net magnetic charge is zero. The gauge potentials are singular along one-half of the z-axis, elsewhere they are regular.

scholarly journals Magnetic Fields in OH Maser Clouds

1974 ◽  
Vol 60 ◽  
pp. 275-292 ◽  
Author(s):  
R. D. Davies
Keyword(s):  
Magnetic Field ◽  
Angular Momentum ◽  
Magnetic Fields ◽  
Magnetic Flux ◽  
Field Data ◽  
Zeeman Splitting ◽  
Galactic Rotation ◽  
Magnetic Field Data ◽  
The Magnetic Field ◽  
Maser Sources

Observations of Class I OH maser sources show a range of features which are predicted on the basis of Zeeman splitting in a source magnetic field. Magnetic field strengths of 2 to 7 mG are derived for eight OH maser sources. The fields in all the clouds are directed in the sense of galactic rotation. A model of W3 OH is proposed which incorporates the magnetic field data. It is shown that no large amount of magnetic flux or angular momentum has been lost since the condensation from the interstellar medium began.

Solar Dynamo

2020 ◽  
Author(s):  
Robert Cameron
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Flux ◽  
Differential Rotation ◽  
Large Scale ◽  
Toroidal Field ◽  
Solar Dynamo ◽  
Small Scale ◽  
The Sun ◽  
The Magnetic Field

The solar dynamo is the action of flows inside the Sun to maintain its magnetic field against Ohmic decay. On small scales the magnetic field is seen at the solar surface as a ubiquitous “salt-and-pepper” disorganized field that may be generated directly by the turbulent convection. On large scales, the magnetic field is remarkably organized, with an 11-year activity cycle. During each cycle the field emerging in each hemisphere has a specific East–West alignment (known as Hale’s law) that alternates from cycle to cycle, and a statistical tendency for a North-South alignment (Joy’s law). The polar fields reverse sign during the period of maximum activity of each cycle. The relevant flows for the large-scale dynamo are those of convection, the bulk rotation of the Sun, and motions driven by magnetic fields, as well as flows produced by the interaction of these. Particularly important are the Sun’s large-scale differential rotation (for example, the equator rotates faster than the poles), and small-scale helical motions resulting from the Coriolis force acting on convective motions or on the motions associated with buoyantly rising magnetic flux. These two types of motions result in a magnetic cycle. In one phase of the cycle, differential rotation winds up a poloidal magnetic field to produce a toroidal field. Subsequently, helical motions are thought to bend the toroidal field to create new poloidal magnetic flux that reverses and replaces the poloidal field that was present at the start of the cycle. It is now clear that both small- and large-scale dynamo action are in principle possible, and the challenge is to understand which combination of flows and driving mechanisms are responsible for the time-dependent magnetic fields seen on the Sun.

scholarly journals Dynamically dominant magnetic fields in the diffuse interstellar medium

2008 ◽  
Vol 4 (S259) ◽  
pp. 87-88 ◽  
Author(s):  
Andrew Fletcher ◽  
M. Korpi ◽  
A. Shukurov
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Flux ◽  
Interstellar Medium ◽  
Numerical Simulations ◽  
Hydrodynamic Model ◽  
Mass Conservation ◽  
Unstable Flow ◽  
Gas Density ◽  
The Magnetic Field

AbstractObservations show that magnetic fields in the interstellar medium (ISM) often do not respond to increases in gas density as would be naively expected for a frozen-in field. This may suggest that the magnetic field in the diffuse gas becomes detached from dense clouds as they form. We have investigated this possibility using theoretical estimates, a simple magneto-hydrodynamic model of a flow without mass conservation and numerical simulations of a thermally unstable flow. Our results show that significant magnetic flux can be shed from dense clouds as they form in the diffuse ISM, leaving behind a magnetically dominated diffuse gas.

Vehicle Detection and Monitoring Setup Based on Anisotropic Magnetoresistance Sensors

2014 ◽  
Vol 605 ◽  
pp. 625-628
Author(s):  
N. Hadjigeorgiou ◽  
D. Kossivakis ◽  
P. Skafidas
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Vehicle Detection ◽  
Magnetic Sensors ◽  
Anisotropic Magnetoresistance ◽  
The Creation ◽  
The Magnetic Field

The evolution in microelectronics and microarchitecture lead to the creation of cheap and reliable embedded magnetic sensors. Anisotropic Magnetoresistors (AMR), being able to measure one axis magnetic fields, have been employed in many applications so far. In this paper AMR sensor (HMC2003) manufactured by Honeywell Inc. was tested for its ability to detect the magnetic field of a vehicle. Two different sensor topologies were examined regarding their performance in vehicle detection and monitoring.

scholarly journals Investigation of Spatially Unresolved Magnetic Field Outside Sunspots Using Hinode/SOT Observations

2016 ◽  
Vol 12 (S325) ◽  
pp. 59-62
Author(s):  
Olga Botygina ◽  
Mykola Gordovskyy ◽  
Vsevolod Lozitsky
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Flux ◽  
Zeeman Effect ◽  
Active Regions ◽  
Line Ratio ◽  
Optical Telescope ◽  
Flux Tubes ◽  
Magnetic Flux Tubes ◽  
The Magnetic Field

AbstractThe structure of photospheric magnetic fields outside sunspots is investigated in three active regions using Hinode/Solar Optical Telescope(SOT) observations. We analyze Zeeman effect in FeI 6301.5 and FeI 6302.5 lines and determine the observed magnetic field value Beff for each of them. We find that the line ratio Beff(6301)/Beff(6302) is close to 1.3 in the range Beff < 0.2 kG, and close to 1.0 for 0.8 kG < Beff < 1.2 kG. We find that the observed magnetic field is formed by flux tubes with the magnetic field strengths 1.3 − 2.3 kG even in places with weak observed magnetic field fluxes. We also estimate the diameters of smallest magnetic flux tubes to be 15 − 20 km.

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