scholarly journals Ion dynamics in the near-Earth magnetotail: Magnetic turbulence versus normal component of the average magnetic field

2002 ◽  
Vol 107 (A10) ◽  
Author(s):  
A. Greco
Keyword(s):  
Magnetic Field ◽  
Normal Component ◽  
Ion Dynamics ◽  
Magnetic Turbulence ◽  
Average Magnetic Field

Ion dynamics in the magnetotail current sheet: opposite effects of magnetic turbulence and normal component

2003 ◽  
Vol 65 (3) ◽  
pp. 315-322 ◽  
Author(s):  
A. Taktakishvili ◽  
R.E. Lopez ◽  
L. Zelenyi ◽  
A. Greco ◽  
G. Zimbardo ◽  
...  
Keyword(s):  
Current Sheet ◽  
Normal Component ◽  
Ion Dynamics ◽  
Magnetic Turbulence ◽  
Magnetotail Current Sheet

Detailed analytical investigation of magnetic field line random walk in turbulent plasmas: II. Isotropic turbulence

2009 ◽  
Vol 75 (2) ◽  
pp. 183-192 ◽  
Author(s):  
I. KOURAKIS ◽  
R. C. TAUTZ ◽  
A. SHALCHI
Keyword(s):  
Magnetic Field ◽  
Random Walk ◽  
Field Line ◽  
Isotropic Turbulence ◽  
Mean Square Displacement ◽  
Analytical Investigation ◽  
Turbulence Spectrum ◽  
Quasilinear Theory ◽  
Magnetic Turbulence ◽  
Field Lines

AbstractThe random walk of magnetic field lines in the presence of magnetic turbulence in plasmas is investigated from first principles. An isotropic model is employed for the magnetic turbulence spectrum. An analytical investigation of the asymptotic behavior of the field-line mean-square displacement 〈(Δx)2〉 is carried out, in terms of the position variable z. It is shown that 〈(Δx)2〉 varies as ~z ln z for large distance z. This result corresponds to a superdiffusive behavior of field line wandering. This investigation complements previous work, which relied on a two-component model for the turbulence spectrum. Contrary to that model, quasilinear theory appears to provide an adequate description of the field-line random walk for isotropic turbulence.

A 4 × 4 array multichannel magnetic stimulation system using submillimeter sized planar square spiral coils: The spatial distribution of electromagnetic field

2022 ◽  
pp. 1-18
Author(s):  
Lei Tian ◽  
Limei Song ◽  
Yu Zheng ◽  
Jinhai Wang
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Field ◽  
Spatial Distribution ◽  
Field Strength ◽  
Electric Field ◽  
Magnetic Stimulation ◽  
Spiral Coil ◽  
Average Magnetic Field ◽  
Stimulation System ◽  
Field Strengths

Multi-coil magnetic stimulation has advantages over single-coil magnetic stimulation, such as more accurate targeting and larger stimulation range. In this paper, a 4 × 4 array multichannel magnetic stimulation system based on a submillimeter planar square spiral coil is proposed. The effects of multiple currents with different directions on the electromagnetic field strength and the focusing zone of the array-structured magnetic stimulation system are studied. The spatial distribution characteristics of the electromagnetic field are discussed. In addition, a method is proposed that can predict the spatial distributions of the electric and magnetic fields when currents in different directions are applied to the array-structured magnetic stimulation system. The study results show that in the section of z = 2 μm, the maximum and average magnetic field strengths of the array-structured magnetic stimulation system are 6.39 mT and 2.68 mT, respectively. The maximum and average electric field strengths are 614.7 mV/m and 122.82 mV/m, respectively, where 84.39% of the measured electric field values are greater than 73 mV/m. The average magnetic field strength of the focusing zone, i.e., the zone in between the two coils, is 3.38 mT with a mean square deviation of 0.18. Therefore, the array-structured multi-channel magnetic stimulation system based on a planar square spiral coil can have a small size of 412 μm × 412 μm × 1.7 μm, which helps improving the spatial distribution of electromagnetic field and increase the effectiveness of magnetic stimulation. The main contribution of this paper is a method for designing multichannel micro-magnetic stimulation devices.

scholarly journals Magnetic turbulence and particle dynamics in the Earth’s magnetotail

2003 ◽  
Vol 21 (9) ◽  
pp. 1947-1953 ◽  
Author(s):  
G. Zimbardo ◽  
A. Greco ◽  
A. L. Taktakishvili ◽  
P. Veltri ◽  
L. M. Zelenyi
Keyword(s):  
Magnetic Field ◽  
Current Sheet ◽  
Sheet Thickness ◽  
Particle Dynamics ◽  
Particle Simulation ◽  
Mhd Waves ◽  
Magnetic Fluctuations ◽  
Magnetic Turbulence ◽  
Magnetospheric Configuration And Dynamics ◽  
Interplanetary Physics

Abstract. The influence of magnetic turbulence in the near-Earth magnetotail on ion motion is investigated by numerical simulation. The magnetotail current sheet is modelled as a magnetic field reversal with a normal magnetic field com-ponent Bn , plus a three-dimensional spectrum of magnetic fluctuations dB which represents the observed magnetic turbulence. The dawn-dusk electric field Ey is also considered. A test particle simulation is performed using different values of Bn and of the fluctuation level dB/B0. We show that when the magnetic fluctuations are taken into account, the particle dynamics is deeply affected, giving rise to an increase in the cross tail transport, ion heating, and current sheet thickness. For strong enough turbulence, the current splits in two layers, in agreement with recent Cluster observations.Key words. Magnetospheric physics (magnetospheric configuration and dynamics) – Interplanetary physics (MHD waves and turbulence) – Electromagnetics (numerical methods)

Spin spatial splitter based on a magnetic nanostructure with zero average magnetic field

2014 ◽  
Vol 313 ◽  
pp. 545-548 ◽  
Author(s):  
Xu-Hui Liu ◽  
Gui-Lian Zhang ◽  
Yong-Hong Kong ◽  
Ai-Hua Li ◽  
Xi Fu
Keyword(s):  
Magnetic Field ◽  
Average Magnetic Field ◽  
Magnetic Nanostructure

Field Topography of Defects in Magnetic Non-Destructive Testing

NDT World ◽  
2015 ◽  
Vol 19 (4) ◽  
pp. 53-56
Author(s):  
Покровский ◽  
Aleksey Pokrovskiy ◽  
Новиков ◽  
Ilya Novikov ◽  
Хвостов ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Fault Location ◽  
Extreme Values ◽  
Accurate Determination ◽  
Normal Component ◽  
Tangential Component ◽  
Destructive Testing ◽  
Hall Sensors

The defect parameters can be evaluated by defect induced magnetic field topography using Hall sensor. Investigations were carried out on specially prepared samples with artificial defects. According to calculations and tests tangential component of magnetic field strength extremes were detected values on either side of the defect in the surface layer l only. But this effect can not be detected by Hall sensors or Foerster probes due to their sizes. The normal component of the magnetic field strength provides a sufficiently accurate determination of the fault location, where this component becomes zero between the two extreme values located quite close to each other. The results of the study showed that at distances available to Hall transducers one can confine to the experimental research, whereas computational methods shall be used to study the topography of field defects at very small distances from the surface. This could open the prospects for testing at small distances from the surface of the object.

Effects of parallel ion dynamics on drift-Alfvén vortices in plasmas

1988 ◽  
Vol 39 (1) ◽  
pp. 151-155 ◽  
Author(s):  
P. K. Shukla
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Ion Dynamics ◽  
Ion Motion

Drift-Alfvén vortices are investigated, taking into account the nonlinear ion dynamics parallel to the external magnetic field. It is found that the parallel ion motion restricts the vortex speed.

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