RADIATION FROM A STRIP OF ELECTRIC CURRENT IN A MAGNETOIONIC MEDIUM

1967 ◽  
Vol 45 (5) ◽  
pp. 1675-1691
Author(s):  
A. D. Wunsch
Keyword(s):  
Magnetic Field ◽  
Resonance Frequency ◽  
Electric Current ◽  
Static Magnetic Field ◽  
Radiation Resistance ◽  
Finite Width ◽  
Hybrid Resonance ◽  
Wide Range ◽  
Field Integral ◽  
A Current

The radiation resistance of a strip of electric current immersed in a cold magnetoplasma is investigated. The current is assumed to flow in a direction perpendicular to the static magnetic field. Integral expressions are obtained for the radiation resistance of a Hertzian dipole and for a current strip of finite width and length. Numerical results covering a wide range of frequencies are presented for both of the sources. It is shown that there are two frequency ranges where the radiation resistance of the Hertzian dipole is infinite, while the radiation resistance of the strip is finite everywhere except at the upper hybrid resonance frequency. The way in which the length of the strip influences its radiation resistance is discussed.

scholarly journals Invariant analytical solutions for the motion of an elastic string with electric current in a static magnetic field

2020 ◽  
Author(s):  
Evgeny Kurmyshev ◽  
Luis Manuel Pi uelas Castro ◽  
Alexander Yakhno ◽  
Liliya Yakhno
Keyword(s):  
Magnetic Field ◽  
Electric Current ◽  
Static Magnetic Field ◽  
Analytical Solutions ◽  
Elastic String

scholarly journals THE MAGNETIC PROPERTIES MEASUREMENT OF COIL FOR GRAVITATIONAL ACCELERATION DETERMINATION

2020 ◽  
Vol 5 (2) ◽  
pp. 119-128
Author(s):  
Cherly Salawane ◽  
Supriyadi Supriyadi ◽  
Ronaldo Talapessy ◽  
Mirtha Yunitha Sari Risakotta
Keyword(s):  
Magnetic Field ◽  
Magnetic Properties ◽  
Field Strength ◽  
Electric Current ◽  
Graphical Method ◽  
Current Strength ◽  
Gravitational Acceleration ◽  
The Earth ◽  
The Magnetic Field ◽  
A Current

The value of the gravitational acceleration of the earth above the earth’s surface depends on the position of the latitude and longitude of the earth’s surface, in other words, because the shape of the earth’s surface is not round like a ball. The magnitude of gravity is not the same everywhere on the surface of the earth. The purpose of this study is to analyze the value of the earth’s gravitational acceleration in a laboratory using a current balance with a graphical method. Fluctuations in the value of the magnetic field strength (B) and the value of the electric current strength (i) on the current balance cause the value of laboratory gravitational acceleration (glab) to vary in the transfer of electric charge (q) according to coil type. The magnitude of the earth’s gravitational acceleration value obtained in a laboratory with a current balance for each type of coil is as follows: SF-37 glab-nr=9.89 m/s2, SF-38 glab-nr=9.90 m/s2, SF-39 glab-nr=9.76 m/s2, SF-40 glab-nr=9.95 m/s2, SF-41 glab-nr=9.75 m/s2 dan SF-42 glab-nr=9.93 m/s2. The results obtained indicate that the value of the earth’s gravitational acceleration in a laboratory close to the literature value is the value of the glab-nr in the SF-37 coil type of 9.89 m/s2.

Galvanomagnetic and thermomagnetic phenomena

2004 ◽  
Author(s):  
Robert E. Newnham
Keyword(s):  
Magnetic Field ◽  
Heat Flow ◽  
Magnetic Fields ◽  
Hall Effect ◽  
Electric Current ◽  
Lorentz Force ◽  
Electrical Resistance ◽  
Magnetic Flux Density ◽  
Wide Range ◽  
The Magnetic Field

The Lorentz force that a magnetic field exerts on a moving charge carrier is perpendicular to the direction of motion and to the magnetic field. Since both electric and thermal currents are carried by mobile electrons and ions, a wide range of galvanomagnetic and thermomagnetic effects result. The effects that occur in an isotropic polycrystalline metal are illustrated in Fig. 20.1. As to be expected, many more cross-coupled effects occur in less symmetric solids. The galvanomagnetic experiments involve electric field, electric current, and magnetic field as variables. The Hall Effect, transverse magnetoresistance, and longitudinal magnetoresistance all describe the effects of magnetic fields on electrical resistance. Analogous experiments on thermal conductivity are referred to as thermomagnetic effects. In this case the variables are heat flow, temperature gradient, and magnetic field. The Righi–Leduc Effect is the thermal Hall Effect in which magnetic fields deflect heat flow rather than electric current. The transverse thermal magnetoresistance (the Maggi–Righi–Leduc Effect) and the longitudinal thermal magnetoresistance are analogous to the two galvanomagnetic magnetoresistance effects. Additional interaction phenomena related to the thermoelectric and piezoresistance effects will be discussed in the next two chapters. In tensor form Ohm’s Law is . . .Ei = ρijJj , . . . where Ei is electrical field, Jj electric current density, and ρij the electrical resistivity in Ωm. In describing the effect of magnetic field on electrical resistance, we expand the resistivity in a power series in magnetic flux density B. B is used rather than the magnetic field H because the Lorentz force acting on the charge carriers depends on B not H.

Stress measurement based on magnetostrictive characteristic parameters

2021 ◽  
Vol 63 (5) ◽  
pp. 283-288
Author(s):  
Entao Yao ◽  
Fei Han ◽  
Ping Wang ◽  
Yuan Zhang
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Static Magnetic Field ◽  
Stress Measurement ◽  
Maximum Relative Error ◽  
Electromagnetic Acoustic Transducer ◽  
Wide Range ◽  
The Relationship ◽  
Non Destructive

Non-destructive testing (NDT) involving stress measurement has found a wide range of applications in rail, pipeline, bridge and other engineering areas and it is therefore necessary to find a method to measure stress. In this paper, a non-destructive method is proposed to measure stress by observation of the magnetostrictive properties of the objects. Stress in the elastic range is applied to the ferromagnetic material, changing its lattice, while stress in the plastic range changes its microstructure. These are the reasons for the magnetostrictive coefficient variation of the material. An experimental platform was set up, using a cantilever beam with a strain gauge, to study the relationship between the SH wave, the static magnetic field strength and the applied uniaxial stress. The curve obtained shows the relationship between the amplitude of the electromagnetic acoustic transducer (EMAT) signal and the static magnetic field strength. The magnetostrictive parameters, sensitive to stress, were extracted from the curve. This method is verified through trials on test samples with a maximum relative error between experimental and predicted values of 8.06%.

An experimental investigation of MHD quasi-two-dimensional turbulent shear flows

2002 ◽  
Vol 456 ◽  
pp. 137-159 ◽  
Author(s):  
KARIM MESSADEK ◽  
RENE MOREAU
Keyword(s):  
Magnetic Field ◽  
Energy Transfer ◽  
Turbulent Flow ◽  
Shear Layer ◽  
Electric Current ◽  
Turbulent Shear ◽  
Two Dimensional ◽  
Joule Dissipation ◽  
Layer Width ◽  
Wide Range

An extensive experimental study is carried out to examine the properties of a quasi-two-dimensional MHD turbulent shear flow. Axisymmetric shear of a mercury layer is enforced by the action of a steady vertical magnetic field and a radial horizontal electric current flowing between a ring set of electrodes and a cylindrical wall. This shear layer is unstable, and the properties of the turbulent flow are studied for a wide range of Hartmann (up to 1800) and Reynolds numbers (up to 106). The mean velocity profiles exhibit a turbulent free shear layer, of thickness larger than that predicted by the laminar theory by two orders of magnitude. The profiles yield the expected linear dependence between the total angular momentum and the electric current when the magnetic field is large enough, but demonstrate a systematic deviation when it is moderate (Ha [lsim ] 250). The quasi-two-dimensional turbulence is characterized by an energy transfer towards the large scales, which leads to a relatively small number of large coherent structures. The properties of these structures result from the competition between the energy transfer and the Joule dissipation within the Hartmann layers. In the intermediate range of wavenumbers (k[lscr ] < k < ki, where k[lscr ] is the integral-length-scale wavenumber and ki the injection wavenumber), the energy spectra exhibit a power law close to k−5/3 when the Joule dissipation is weak and close to k−3 when it is significant. The properties of the turbulent flow in this latter regime depend on only one non-dimensional parameter, the ratio (Ha/Re)(l⊥/h)2 (Ha is the Hartmann number, Re the Reynolds number based on the cell radius, l⊥ a typical transverse scale, and h the layer width).

Current Induced G-Factor Shift in Modulation Doped Si Quantum Wells

2006 ◽  
Vol 984 ◽  
Author(s):  
Hans Malissa ◽  
Wolfgang Jantsch ◽  
Friedrich Schäffler ◽  
Zbyslaw Wilamowski
Keyword(s):  
Magnetic Field ◽  
Quantum Wells ◽  
Electric Current ◽  
Magnetic Field Direction ◽  
G Factor ◽  
Conduction Electrons ◽  
Simple Effect ◽  
Spin Resonance ◽  
The Magnetic Field ◽  
A Current

AbstractWe report the observation of a particularly simple effect of spin-orbit coupling which allows for efficient manipulation of spins by an electric current in semiconductor nanostructures. Passing an electric current density of j = 2.5 mA/cm through a modulation doped Si quantum well (density of 5 × 1011 cm-2) perpendicular to an in-plane magnetic field, we observe a shift of the spin resonance of the conduction electrons (CESR) by about 0.1 mT. This shift reverses sign when we invert (i) the current direction, (ii) the magnetic field direction and it vanishes for perpendicular magnetic field. We show that this current-induced shift in g-factor, i.e., its dependence on current and carrier density, its temperature dependence and its anisotropy can be consistently and quantitatively explained in terms of the Bychkov-Rashba coefficient determined earlier from the CESR broadening and the g-factor anisotropy [1]. Other sources of magnetic field (e.g. the Oersted effect) are negligible. This effect can be utilized for g-factor tuning, and thus for local spin manipulation: passing a current through some part of a sample may be utilized to bring those electrons into resonance with a microwave field. These spins are thus excited to Rabi oscillations and, using current pulses of suitable duration, π rotations (or by any other angle) can be achieved.

scholarly journals Intermediate shock sub-structures within a slow-mode shock occurring in partially ionised plasma

2019 ◽  
Vol 626 ◽  
pp. A46 ◽  
Author(s):  
B. Snow ◽  
A. Hillier
Keyword(s):  
Magnetic Field ◽  
Initial Conditions ◽  
Frictional Heating ◽  
Physical Parameters ◽  
Solar Chromosphere ◽  
Finite Width ◽  
Slow Mode ◽  
Wide Range ◽  
Intermediate Shock ◽  
The Magnetic Field

Context. Slow-mode shocks are important in understanding fast magnetic reconnection, jet formation and heating in the solar atmosphere, and other astrophysical systems. The atmospheric conditions in the solar chromosphere allow both ionised and neutral particles to exist and interact. Under such conditions, fine sub-structures exist within slow-mode shocks due to the decoupling and recoupling of the plasma and neutral species. Aims. We study numerically the fine sub-structure within slow-mode shocks in a partially ionised plasma, in particular, analysing the formation of an intermediate transition within the slow-mode shock. Methods. High-resolution 1D numerical simulations were performed using the (PIP) code using a two-fluid approach. Results. We discover that long-lived intermediate (Alfvén) shocks can form within the slow-mode shock, where there is a shock transition from above to below the Alfvén speed and a reversal of the magnetic field across the shock front. The collisional coupling provides frictional heating to the neutral fluid, resulting in a Sedov-Taylor-like expansion with overshoots in the neutral velocity and neutral density. The increase in density results in a decrease of the Alfvén speed and with this the plasma inflow is accelerated to above the Alfvén speed within the finite width of the shock leading to the intermediate transition. This process occurs for a wide range of physical parameters and an intermediate shock is present for all investigated values of plasma-β, neutral fraction, and magnetic angle. As time advances the magnitude of the magnetic field reversal decreases since the neutral pressure cannot balance the Lorentz force. The intermediate shock is long-lived enough to be considered a physical structure, independent of the initial conditions. Conclusions. Intermediate shocks are a physical feature that can exist as shock sub-structure for long periods of time in partially ionised plasma due to collisional coupling between species.

scholarly journals Invariant analytical solutions for the motion of an elastic string with electric current in a static magnetic field

2021 ◽  
Author(s):  
Evgeny Kurmyshev ◽  
Luis M. Piñuelas Castro ◽  
Alexander Yakhno ◽  
Liliya Yakhno
Keyword(s):  
Magnetic Field ◽  
Electric Current ◽  
Static Magnetic Field ◽  
Analytical Solutions ◽  
Elastic String
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