scholarly journals Terahertz Characteristics of Magnetic Fluid Based on Microfluidic Technology

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Xinyuan Zhao ◽  
Guoyang Wang ◽  
Siyu Shao ◽  
Qinghao Meng ◽  
Jiahui Wang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Electric Fields ◽  
Field Intensity ◽  
Magnetic Fluid ◽  
Terahertz Technology ◽  
Terahertz Spectrum ◽  
Microfluidic Technology ◽  
Terahertz Transmission ◽  
The Magnetic Field

Magnetic fluid is a new functional material with both liquid fluidity and solid magnetism, which has important application value in medicine, biology, and so on. In this study, terahertz technology and microfluidic technology were combined to investigate the terahertz transmission characteristics of a magnetic fluid in different magnetic fields and different electric fields. In the external magnetic field, the intensity of the terahertz spectrum increased with an increase in the magnetic field intensity, and the response to the magnetic field in different directions was different. Under the applied electric field, the intensity of the terahertz spectrum decreased with an increase in the electric field intensity. This method is convenient for studying the terahertz characteristics of magnetic fluid and provides technical support for in-depth studies of magnetic fluid.

scholarly journals Mapping of steady-state electric fields and convective drifts in geomagnetic fields – Part 1: Elementary models

2016 ◽  
Vol 34 (1) ◽  
pp. 55-65 ◽  
Author(s):  
A. D. M. Walker ◽  
G. J. Sofko
Keyword(s):  
Magnetic Field ◽  
Steady State ◽  
Electric Field ◽  
Electric Fields ◽  
Magnetic Field Line ◽  
Geomagnetic Field ◽  
Geomagnetic Field Models ◽  
Spatial Derivatives ◽  
Field Lines ◽  
The Magnetic Field

Abstract. When studying magnetospheric convection, it is often necessary to map the steady-state electric field, measured at some point on a magnetic field line, to a magnetically conjugate point in the other hemisphere, or the equatorial plane, or at the position of a satellite. Such mapping is relatively easy in a dipole field although the appropriate formulae are not easily accessible. They are derived and reviewed here with some examples. It is not possible to derive such formulae in more realistic geomagnetic field models. A new method is described in this paper for accurate mapping of electric fields along field lines, which can be used for any field model in which the magnetic field and its spatial derivatives can be computed. From the spatial derivatives of the magnetic field three first order differential equations are derived for the components of the normalized element of separation of two closely spaced field lines. These can be integrated along with the magnetic field tracing equations and Faraday's law used to obtain the electric field as a function of distance measured along the magnetic field line. The method is tested in a simple model consisting of a dipole field plus a magnetotail model. The method is shown to be accurate, convenient, and suitable for use with more realistic geomagnetic field models.

INFLUENCE OF THE MAGNETIC FIELD ON THE TRANSVERSE RUNAWAY THRESHOLD

2007 ◽  
Vol 21 (10) ◽  
pp. 1715-1720 ◽  
Author(s):  
NANA METREVELI ◽  
ZAUR KACHLISHVILI ◽  
BEKA BOCHORISHVILI
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Electric Fields ◽  
Applied Electric Field ◽  
Nonlinear Oscillations ◽  
Hot Electrons ◽  
Total Field ◽  
Practical Applications ◽  
Energy And Momentum ◽  
The Magnetic Field

The transverse runaway (TR) is a phenomenon whereby for a certain combination of energy and momentum scattering mechanisms of hot electrons, and for a certain threshold of the applied electric field, the internal (total) field tends to infinity. In this work, the effect of the magnetic field on the transverse runaway threshold is considered. It is shown that with increasing magnetic field, the applied critical electric fields relevant to TR decrease. The obtained results are important for practical applications of the TR effect as well as for the investigation of possible nonlinear oscillations that may occur near the TR threshold.

Improved the Performance of Focusing Deep Hyperthermia Inductive Heating for Breast Cancer Treatment by Using Ferro-Fluid with Magnetic Shielding System

2013 ◽  
Vol 325-326 ◽  
pp. 353-358 ◽  
Author(s):  
Thosdeekoraphat Thanaset ◽  
Santalunai Samran ◽  
Thongsopa Chanchai
Keyword(s):  
Magnetic Field ◽  
Field Intensity ◽  
Magnetic Fluid ◽  
Magnetic Field Intensity ◽  
Magnetic Shielding ◽  
Inductive Heating ◽  
Surrounding Healthy Tissue ◽  
The Magnetic Field ◽  
Shielding System ◽  
Deep Hyperthermia

The performance improved of focusing deep hyperthermia inductive heating for breast cancer treatment using magnetic fluid nanoparticles with magnetic shielding system has been presented in the paper and the results are discussed. It is a technique challenge in hyperthermia therapy is to control locally heat the tumor region up to an appropriate temperature to destroy cancerous cells, without damaging the surrounding healthy tissue by using magnetic fluid nanoparticles and cylindrical metal shielding with aperture. We show that the magnetic field intensity can be controlled by changing the aperture size to suitable. In addition, the position of the heating can be controlled very well with the magnetic fluid together with shielding system. In the simulation, the inductive applicator is a ferrite core with diameter of 7 cm and excited by 4 MHz signal. Results have shown that the temperature increments depend on the magnetic fluid nanoparticles. In addition, the magnetic field intensity without damaging the surrounding healthy tissue when used magnetic shielded system. These results demonstrate that it is possible to achieve higher temperatures and to focus magnetic field intensity where the nanoparticles and magnetic shielding system are used.

scholarly journals Ion energy increase in laser-generated plasma expanding through axial magnetic field trap

2007 ◽  
Vol 25 (3) ◽  
pp. 453-464 ◽  
Author(s):  
L. Torrisi ◽  
D. Margarone ◽  
S. Gammino ◽  
L. Andò
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Electric Fields ◽  
Axial Magnetic Field ◽  
Ion Beam ◽  
High Vacuum ◽  
Target Surface ◽  
Axial Direction ◽  
Ion Interactions ◽  
The Magnetic Field

Laser-generated plasma is obtained in high vacuum (10−7 mbar) by irradiation of metallic targets (Al, Cu, Ta) with laser beam with intensities of the order of 1010 W/cm2. An Nd:Yag laser operating at 1064 nm wavelength, 9 ns pulse width, and 500 mJ maximum pulse energy is used. Time of flight measurements of ion emission along the direction normal to the target surface were performed with an ion collector. Measurements with and without a 0.1 Tesla magnetic field, directed along the normal to the target surface, have been taken for different target-detector distances and for increasing laser pulse intensity. Results have demonstrated that the magnetic field configuration creates an electron trap in front of the target surface along the axial direction. Electric fields inside the trap induce ion acceleration; the presence of electron bundles not only focuses the ion beam but also increases its energy, mean charge state and current. The explanation of this phenomenon can be found in the electric field modification inside the non-equilibrium plasma because of an electron bunching that increases the number of electron-ion interactions. The magnetic field, in fact, modifies the electric field due to the charge separation between the clouds of fast electrons, many of which remain trapped in the magnetic hole, and slow ions, ejected from the ablated target; moreover it increases the number of electron-ion interactions producing higher charge states.

Suppression of runaway of electrons in a Lorentz plasma. II. crossed electric and magnetic fields

1970 ◽  
Vol 4 (3) ◽  
pp. 441-450 ◽  
Author(s):  
Barbara Abraham-Shrauner
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Electric Field ◽  
Electric Fields ◽  
Cyclotron Frequency ◽  
Collision Frequency ◽  
Uniform Electric Field ◽  
Drift Motion ◽  
Electric And Magnetic Fields ◽  
The Magnetic Field

Suppression of runaway of electrons in a weak, uniform electric field in a fully ionized Lorentz plasma by crossed magnetic and electric fields is analysed. A uniform, constant magnetic field parallel to a constant or harmonically time varying electric field does not alter runaway from that in the absence of the magnetic field. For crossed, constant fields the passage to runaway or to free motion as described by constant drift motion and spiral motion about the magnetic field is lengthened in time for strong magnetic fields. The new ‘runaway’ time scale is roughly the ratio of the cyclotron frequency to the collision frequency squared for cyclotron frequencies much greater than the collision frequency. All ‘runaway’ time scales may be given approximately by t2E Teff where tE is the characteristic time of the electric field and Teff is the ffective collision time as estimated from the appropriate component of the electrical conductivity.

SEQUENTIAL RESONANT TUNNELING BETWEEN LANDAU LEVELS IN GaAs\AlGaAs SUPERLATTICES IN STRONG TILTED MAGNETIC AND ELECTRIC FIELDS

2007 ◽  
Vol 21 (08n09) ◽  
pp. 1594-1599 ◽  
Author(s):  
M. P. TELENKOV ◽  
YU. A. MITYAGIN
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Electric Fields ◽  
Resonant Tunneling ◽  
Landau Levels ◽  
Domain Formation ◽  
Tunneling Transition ◽  
The Magnetic Field ◽  
Component Parallel ◽  
Tilted Magnetic Field

The transverse resonant tunneling transport and electric field domain formation in GaAs/AlGaAs superlattices were investigated in a strong tilted magnetic field. The magnetic field component parallel to structure layers causes intensive tunneling transition between Landau levels with Δn≠0, resulting in the considerable "inhomogeneous" broadening of intersubband tunneling resonance as well as in the shift of the resonance toward higher electric fields. This leads to noticeable changes of the I-V characteristics of the superlattice, namely to smoothing of the periodic NDC structure on plateau-like regions caused by formation of the electric field domains and to the shift of the plateaus toward the higher applied voltage. The predicted behavior of the I-V characteristics of the structures in magnetic field was found experimentally.

scholarly journals Tripolar electric field Structure in guide field magnetic reconnection

2018 ◽  
Vol 36 (2) ◽  
pp. 373-379 ◽  
Author(s):  
Song Fu ◽  
Shiyong Huang ◽  
Meng Zhou ◽  
Binbin Ni ◽  
Xiaohua Deng
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Magnetic Reconnection ◽  
Electric Fields ◽  
Particle Simulation ◽  
Space Plasma Physics ◽  
Guide Field ◽  
Substantial Modification ◽  
Reconnection Layer ◽  
The Magnetic Field

Abstract. It has been shown that the guide field substantially modifies the structure of the reconnection layer. For instance, the Hall magnetic and electric fields are distorted in guide field reconnection compared to reconnection without guide fields (i.e., anti-parallel reconnection). In this paper, we performed 2.5-D electromagnetic full particle simulation to study the electric field structures in magnetic reconnection under different initial guide fields (Bg). Once the amplitude of a guide field exceeds 0.3 times the asymptotic magnetic field B0, the traditional bipolar Hall electric field is clearly replaced by a tripolar electric field, which consists of a newly emerged electric field and the bipolar Hall electric field. The newly emerged electric field is a convective electric field about one ion inertial length away from the neutral sheet. It arises from the disappearance of the Hall electric field due to the substantial modification of the magnetic field and electric current by the imposed guide field. The peak magnitude of this new electric field increases linearly with the increment of guide field strength. Possible applications of these results to space observations are also discussed. Keywords. Space plasma physics (magnetic reconnection)

scholarly journals Polar and Cluster observations of a dayside inverted-V during conjunction

2007 ◽  
Vol 25 (2) ◽  
pp. 543-555 ◽  
Author(s):  
J. D. Menietti ◽  
R. A. Frahm ◽  
A. Korth ◽  
F. S. Mozer ◽  
Y. Khotyaintsev
Keyword(s):  
Magnetic Field ◽  
Boundary Layer ◽  
Electric Field ◽  
Electric Fields ◽  
Magnetic Field Line ◽  
Large Amplitude ◽  
Field Data ◽  
Plasma Waves ◽  
Magnetic Field Data ◽  
The Magnetic Field

Abstract. We investigate particle and fields data during a conjunction of the Polar and Cluster spacecraft. This conjunction occurs near the dayside cusp boundary layer when a dayside inverted-V was observed in the particle data of both satellites. Electron, ion, electric field, and magnetic field data from each satellite confirm that the dayside inverted-V (DSIV) structure is present at the location of both satellites and the electric fields persist from the altitude of the Polar (lower) spacecraft to the altitude of the Cluster spacecraft. We observe accelerated, precipitating electrons and upward ions along the magnetic field. In addition, large amplitude electric fields perpendicular to the ambient magnetic field seen by Polar and by Cluster suggest significant parallel electric fields associated with these events. For similar DSIV events observed by the Polar spacecraft, plasma waves (identified as possible Alfvén waves) have been observed to propagate in both directions along the magnetic field line. Future conjunctions will be necessary to confirm that DSIVs are associated with reconnection sites.

scholarly journals Electron Acceleration by Strong DC Electric Fields in Extragalactic Jets

2000 ◽  
Vol 195 ◽  
pp. 311-312
Author(s):  
Y. E. Litvinenko
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Magnetic Reconnection ◽  
Current Sheet ◽  
Electric Fields ◽  
Electron Acceleration ◽  
Acceleration Time ◽  
Extragalactic Jets ◽  
Dc Electric Field ◽  
The Magnetic Field

Fast magnetic reconnection in extragalactic jets leads to electron acceleration by the DC electric field in the reconnecting current sheet. The maximum electron energy (γ > 106) and the acceleration time (< 106 s) are determined by the magnetic field dynamics in the sheet.

Seismoelectric wave conversions in porous media: Field measurements and transfer function analysis

Geophysics ◽  
2001 ◽  
Vol 66 (5) ◽  
pp. 1417-1430 ◽  
Author(s):  
Stéphane Garambois ◽  
Michel Dietrich
Keyword(s):  
Magnetic Field ◽  
Dielectric Constant ◽  
Electric Field ◽  
Electric Fields ◽  
Field Experiments ◽  
Transfer Functions ◽  
Function Analysis ◽  
Transfer Function Analysis ◽  
Electromagnetic Disturbances ◽  
The Magnetic Field

We present a series of field experiments showing the transient electric fields generated by a seismic excitation of the subsurface. After removing the powerline noise by adaptive filtering, the most prominent feature of the seismoelectric recordings is the presence of electric signals very similar to conventional seismic recordings. In one instance, we identified small‐amplitude precursory electromagnetic disturbances showing a polarity reversal on either side of the shotpoint. Concentrating on the dominant seismoelectric effect, we theoretically show that the electric field accompanying the compressional waves is approximately proportional to the grain acceleration. We also demonstrate that the magnetic field moving along with shear waves is roughly proportional to the grain velocity. These relationships hold true as long as the displacement currents are much smaller than the conduction currents (diffusive regime), which is normally the case in the low‐frequency range used in seismic prospecting. Furthermore, the analytical transfer functions thus obtained indicate that the electric field is mainly sensitive to the salt concentration and dielectric constant of the fluid, whereas the magnetic field principally depends on the shear modulus of the framework of grains and on the fluid’s viscosity and dielectric constant. Both transfer functions are essentially independent of the permeability. Our results suggest that the simultaneous recording of seismic, electric, and magnetic wavefields can be useful for characterizing porous layers at two different levels of investigation: near the receivers and at greater depth.

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