helical field
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2021 ◽  
Author(s):  
Vitaly Kuyukov

Helical field quantum gravity



2020 ◽  
Vol 499 (3) ◽  
pp. 3673-3689
Author(s):  
J L West ◽  
R N Henriksen ◽  
K Ferrière ◽  
A Woodfinden ◽  
T Jaffe ◽  
...  

ABSTRACT We search for observational signatures of magnetic helicity in data from all-sky radio polarization surveys of the Milky Way Galaxy. Such a detection would help confirm the dynamo origin of the field and may provide new observational constraints for its shape. We compare our observational results to simulated observations for both a simple helical field, and for a more complex field that comes from a solution to the dynamo equation. Our simulated observations show that the large-scale helicity of a magnetic field is reflected in the large-scale structure of the fractional polarization derived from the observed synchrotron radiation and Faraday depth of the diffuse Galactic synchrotron emission. Comparing the models with the observations provides evidence for the presence of a quadrupolar magnetic field with a vertical component that is pointing away from the observer in both hemispheres of the Milky Way Galaxy. Since there is no reason to believe that the Galactic magnetic field is unusual when compared to other galaxies, this result provides further support for the dynamo origin of large-scale magnetic fields in galaxies.



2020 ◽  
Vol 86 (5) ◽  
Author(s):  
Anton V. Sudnikov ◽  
Aleksey D. Beklemishev ◽  
Anna A. Inzhevatkina ◽  
Ivan A. Ivanov ◽  
Vladimir V. Postupaev ◽  
...  

The paper presents experimental results from the SMOLA device that is the first facility with a helical mirror section of the magnetic field. This device is built in the Budker Institute of Nuclear Physics for the verification of the helical mirror confinement idea that is the recently introduced technique of the active control of axial losses from a confinement zone. Theory predicts that with rotating plasma, a helical mirror will provide suppression of the axial plasma flow and, simultaneously, density pinching to the axis. Experiments demonstrated that plasma density at the exit from the transport section is suppressed with activation of the helical field, the effect is significant and highly reproducible. The most pronounced effect is observed on the plasma periphery, where the mirror ratio is the highest. The integral suppression ratio reaches 2–2.5 in the discussed experiments. Experimental results are compared with simplified theoretical estimates. The integral suppression ratio matches the simple theoretical estimates even if the transversal diffusion is neglected.



Science ◽  
2019 ◽  
Vol 365 (6460) ◽  
pp. 1449-1453 ◽  
Author(s):  
Jung-Shen B. Tai ◽  
Ivan I. Smalyukh

Starting with Gauss and Kelvin, knots in fields were postulated to behave like particles, but experimentally they were found only as transient features or required complex boundary conditions to exist and could not self-assemble into three-dimensional crystals. We introduce energetically stable, micrometer-sized knots in helical fields of chiral liquid crystals. While spatially localized and freely diffusing in all directions, they resemble colloidal particles and atoms, self-assembling into crystalline lattices with open and closed structures. These knots are robust and topologically distinct from the host medium, though they can be morphed and reconfigured by weak stimuli under conditions such as those in displays. A combination of energy-minimizing numerical modeling and optical imaging uncovers the internal structure and topology of individual helical field knots and the various hierarchical crystalline organizations that they form.



2018 ◽  
Vol 982 ◽  
pp. 012004 ◽  
Author(s):  
B. Mahdavipour ◽  
A. Salar Elahi ◽  
M. Ghoranneviss


Author(s):  
Boris Filippov

AbstractInterest to lateral details of the solar filament shape named barbs, motivated by their relationship to filament chirality and helicity, showed their different orientation relative to the expected direction of the magnetic field. While the majority of barbs are stretched along the field, some barbs seem to be transversal to it and are referred to as anomalous barbs. We analyse the deformation of helical field lines by a small parasitic polarity using a simple flux rope model with a force-free field. A rather small and distant source of parasitic polarity stretches the bottom parts of the helical lines in its direction creating a lateral extension of dips below the flux-rope axis. They can be considered as normal barbs of the filament. A stronger and closer source of parasitic polarity makes the flux-rope field lines to be convex below its axis and creates narrow and deep dips near its position. As a result, the narrow structure, with thin threads across it, is formed whose axis is nearly perpendicular to the field. The structure resembles an anomalous barb. Hence, the presence of anomalous barbs does not contradict the flux-rope structure of a filament.



2016 ◽  
Vol 688 ◽  
pp. 012072
Author(s):  
Toseo Moritaka ◽  
Youichi Sakawa ◽  
Yasuhiro Kuramitsu ◽  
Taichi Morita ◽  
Yuta Yamaura ◽  
...  


2016 ◽  
Vol 11 (0) ◽  
pp. 2402074-2402074 ◽  
Author(s):  
Tatsuya SAKITO ◽  
Hideki ARIMOTO ◽  
Takaaki FUJITA ◽  
Atsushi OKAMOTO ◽  
Yusuke SHIMOOKA ◽  
...  


Author(s):  
Adrian Belanger ◽  
Tod Barker

Hard spots are serious threats to pipeline operations, especially in pre-1970s vintage pipe where they were unintentionally created in the manufacturing process. Steels with high hardness and tensile strength are susceptible to hydrogen induced cracking (HIC) and thus hard spots with hardnesses higher than that of the surrounding base material are areas in need of remediative action. One course of remediation has been sleeving, but if the sleeve is not properly sealed to the pipe, cracking can be accelerated due to the trapping of moisture. An inspection with multiple data sets (MDS) is capable of identifying hard spots through the use of high and low levels of magnetization and identifying cracking even in sleeved areas using helical field technology. This paper will show the initial tests that were done using an 18-inch MDS tool to measure different types of hardening and quenching. The results are compared to actual hard spots from a 30-inch diameter vintage pipe before and after notches were made, both with and without sleeves. The ability to assess hardness and the detectability of cracking is discussed.



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