A Point-wise Solution for the Magnetic Field Vector

2002 ◽  
Author(s):  
Andrew A. Thompson
Keyword(s):  
Magnetic Field ◽  
Field Vector ◽  
Magnetic Field Vector ◽  
The Magnetic Field

scholarly journals DEVICE FOR RESEARCHES OF MAGNETIC FIELD IMPACT UPON “WHEEL-RAIL” FRICTION PAIR CHARACTERISTICS

2020 ◽  
Vol 2020 (1) ◽  
pp. 34-39
Author(s):  
Dmitriy Antipin ◽  
Vladimir Vorob'ev ◽  
Maksim Maslov ◽  
Vadim Korchagin
Keyword(s):  
Magnetic Field ◽  
Friction Pair ◽  
Point Contact ◽  
Field Vector ◽  
Magnetic Field Vector ◽  
Original Design ◽  
Magnetic Conductor ◽  
Magnetizing Force ◽  
The Impact ◽  
The Magnetic Field

The paper is dedicated to the circuit diagram substantiation of the specialized roller bench for researches of the magnetic field impact upon wheel adhesion with a rail. On the basis of the analysis of the experimental plants available at present for the study of the contact interaction of wheels with rails it is defined that two-roller benches are the most efficient for the investigation of different outer factors impact upon wheel adhesion with a rail. Taking into account mentioned above there is offered an original design of the two-roller bench equipped with the device for friction area magnetization. Two cylinders with parallel axes are theoretically a friction pair. Taking into account the presence of a non-concurrency arisen at roller manufacturing and mounting a point contact is realized in the bench. A bench formation is carried out according to a modular approach with the installation of rotary magnetic conductors. For the support of the largest magnetization of a friction area in longitudinal and transverse directions and for the decrease of stray flux in the bench there is realized a series connection of roller friction area with the sources of a magnetizing force. For the substantiation of rotary magnetic conductor position choice regarding a friction area of bench rollers there is carried out an analysis of magnetic field distribution in the friction area depending on the location of magnetic conductors. On the basis of the investigation results it is defined that a change of magnetic conductor position changes the orientation of a magnetic field vector, at that a roller friction area is magnetized in transverse and longitudinal directions. In view of this the bench design offered allows investigating the impact of longitudinal and cross magnetic fields upon friction in the contact of a wheel with a rail. Furthermore, it is defined that at small values of an angle between the direction of a magnetic field vector and the plane of a roller friction area a possibility to exclude the effect of roller magnetic additional loading appears.

scholarly journals Magnetic Absorption of Metal Nanoparticles

2018 ◽  
Vol 63 (10) ◽  
pp. 906 ◽  
Author(s):  
P. M. Tomchuk ◽  
V. M. Starkov
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Wave ◽  
Metal Nanoparticles ◽  
Symmetry Axis ◽  
Field Vector ◽  
Magnetic Field Vector ◽  
Incident Electromagnetic Wave ◽  
The Magnetic Field

The dependences of the magnetic absorption by spheroidal metal nanoparticles on the ratio between the particle curvature radii and the angle between the spheroid symmetry axis and the magnetic field vector of an incident electromagnetic wave are plotted and theoretically analyzed. An interesting result of the research is the growth of the energy absorbed by a spheroidal nanoparticle, as it becomes more oblate.

scholarly journals Temporal evolution of short-lived penumbral microjets

2020 ◽  
Vol 642 ◽  
pp. A128
Author(s):  
A. L. Siu-Tapia ◽  
L. R. Bellot Rubio ◽  
D. Orozco Suárez ◽  
R. Gafeira
Keyword(s):  
Magnetic Field ◽  
Temporal Evolution ◽  
Spectral Characteristics ◽  
Field Approximation ◽  
Weak Field ◽  
Field Vector ◽  
Magnetic Field Vector ◽  
Maximum Brightness ◽  
Time Variations ◽  
The Magnetic Field

Context. Penumbral microjets (PMJs) is the name given to elongated jet-like brightenings observed in the chromosphere above sunspot penumbrae. They are transient events that last from a few seconds to several minutes, and their origin is presumed to be related to magnetic reconnection processes. Previous studies have mainly focused on their morphological and spectral characteristics, and more recently on their spectropolarimetric signals during the maximum brightness stage. Studies addressing the temporal evolution of PMJs have also been carried out, but they are based on spatial and spectral time variations only. Aims. Here we investigate, for the first time, the temporal evolution of the polarization signals produced by short-lived PMJs (lifetimes < 2 min) to infer how the magnetic field vector evolves in the upper photosphere and mid-chromosphere. Methods. We use fast-cadence spectropolarimetric observations of the Ca II 854.2 nm line taken with the CRisp Imaging Spectropolarimeter at the Swedish 1 m Solar Telescope. The weak-field approximation (WFA) is used to estimate the strength and inclination of the magnetic field vector. By separating the Ca II 854.2 nm line into two different wavelength domains to account for the chromospheric origin of the line core and the photospheric contribution to the wings, we infer the height variation of the magnetic field vector. Results. The WFA reveals larger magnetic field changes in the upper photosphere than in the chromosphere during the PMJ maximum brightness stage. In the photosphere, the magnetic field inclination and strength undergo a transient increase for most PMJs, but in 25% of the cases the field strength decreases during the brightening. In the chromosphere, the magnetic field tends to be slightly stronger during the PMJs. Conclusions. The propagation of compressive perturbation fronts followed by a rarefaction phase in the aftershock region may explain the observed behavior of the magnetic field vector. The fact that such behavior varies among the analyzed PMJs could be a consequence of the limited temporal resolution of the observations and the fast-evolving nature of the PMJs.

scholarly journals Magnetic field vector ambiguity resolution in a quiescent prominence observed on two consecutive days

2019 ◽  
Vol 629 ◽  
pp. A138 ◽  
Author(s):  
T. Kalewicz ◽  
V. Bommier
Keyword(s):  
Magnetic Field ◽  
Solar Rotation ◽  
Field Vector ◽  
Magnetic Field Vector ◽  
Stokes Parameters ◽  
Absolute Value ◽  
The Past ◽  
Tenerife Island ◽  
The Magnetic Field ◽  
European Site

Context. Magnetic field vector measurements are always ambiguous, that is, two or more field vectors are solutions of the observed polarisation. Aims. The aim of the present paper is to solve the ambiguity by comparing the ambiguous field vectors obtained in the same prominence observed on two consecutive days. The effect of the solar rotation is to modify the scattering angle of the prominence radiation, which modifies the symmetry of the ambiguous solutions. This method, which is a kind of tomography, was successfully applied in the past to the average magnetic field vector of 20 prominences observed at the Pic du Midi. The aim of the present paper is to apply this method to a prominence observed with spatial resolution at the THÉMIS telescope (European site at Izaña, Tenerife Island). Methods. The magnetic field vector is measured by interpretation of the Hanle effect observed in the He I D3 5875.6 Å line, within the horizontal field vector hypothesis for simplicity. The ambiguity is first solved by comparing the two pairs of solutions obtained for a “big pixel” determined by averaging the observed Stokes parameters in a large region at the prominence centre. Each pixel is then disambiguated by selecting the closest solution in a propagation from the prominence centre to the prominence boundary. Results. The results previously obtained on averaged prominences are all recovered. The polarity is found to be inverse with a small angle of about −21° between the magnetic field vector and the long axis of the filament. The magnetic field strength of about 6 G is found to slightly increase with height, as previously observed. The new result is the observed decrease with height, of the absolute value of the angle between the magnetic field vector and the long axis of the filament. Conclusions. This result is in excellent agreement with prominence magnetohydrodynamical models.

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