scholarly journals Townsend Discharges in Transverse Magnetic Fields

1983 ◽  
Vol 36 (6) ◽  
pp. 859 ◽  
Author(s):  
HA Blevin ◽  
MJ Brennan
Keyword(s):  
Magnetic Field ◽  
Steady State ◽  
Magnetic Fields ◽  
Drift Velocity ◽  
Transverse Magnetic Field ◽  
Electron Concentration ◽  
Diffusion Coefficients ◽  
Concentration Distribution ◽  
Transverse Magnetic ◽  
Electron Drift

Expressions are derived for the electron concentration in Townsend discharges in the presence of a transverse magnetic field for both steady state and pulsed conditions. These results indicate that the two components of the electron drift velocity and the four diffusion coefficients required to describe the concentration distribution can be determined by observation of photons emitted from the discharge.

scholarly journals New Calibration Parameter for Observations of Transverse Solar Magnetic Fields in the Fe I 5324.19 Å Line

1993 ◽  
Vol 141 ◽  
pp. 196-198
Author(s):  
Weihong Song ◽  
Guoxiang Ai
Keyword(s):  
Magnetic Field ◽  
Numerical Analysis ◽  
Magnetic Fields ◽  
Computational Model ◽  
Transverse Magnetic Field ◽  
Transverse Magnetic ◽  
Square Root ◽  
Solar Magnetic Fields ◽  
Doppler Broadening ◽  
Theoretical And Numerical Analysis

AbstractAdopting the computational model of papers I and II (Song et al. 1990, 1992) we have found that for a better fit of the center of the Fe I 5324.19 Å line, the effect of turbulent Doppler broadening has to be taken into account. Through theoretical and numerical analysis we conclude that the square root of the modulus of Stokes Q and U is an appropiate observational parameter to represent the transverse magnetic field, since it is approximately linearly proportional to the strength of the transverse magnetic field for suitable positions of the filter passband.

scholarly journals A Synthesized Method for Solving the 180° Ambiguity of Solar Transverse Magnetic Field

1993 ◽  
Vol 141 ◽  
pp. 461-464
Author(s):  
Wang Huaning ◽  
Lin Yuanzhang
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Transverse Magnetic Field ◽  
Field Model ◽  
Zeeman Effect ◽  
Free Field ◽  
Active Regions ◽  
Transverse Magnetic ◽  
Vector Magnetograms ◽  
Divergence Equation

The 180° ambiguity of the transverse magnetic field measured by a heliomagnetograph is an intrinsic problem due to the linear polarization in Zeeman effect(Harvey, 1969). Thus we have to make use of some criteria for calibrating the transverse magnetic fields in vector magnetograms. Up to now, a few criteria have been suggested by some solar physicists (Harvey, 1969; Krall et al., 1982; Sakurai et al., 1985; Aly, 1989; Wu and Ai, 1990; Canfield et al., 1991. The existing criteria could be classified as observational criteria and mathematical criteria. The former is based on the observation facts, such as the fibrils and the filaments in solar filtergrams, and the latter is derived from the mathematical model of solar magnetic field, such as divergence equation (∆. B = 0), potential field model and force-free field model. These criteria, however, are not applicable to all solar active regions, especially to those with complicated magnetic fields. For this reason, we suggest a synthesized method for calibrating the transverse magnetic fields in solar vector magnetograms.

Galvanomagnetic Properties of Cd3As2- MnAs (MnAs - 20%) System in Transverse Magnetic Field at Hydrostatic Pressure up to 9 Gpa

2020 ◽  
Vol 28 ◽  
pp. 3-8
Author(s):  
Louisa A. Saypulaeva ◽  
Shapiullah B. Abdulvagidov ◽  
Magomed M. Gadjialiev ◽  
Abdulabek G. Alibekov ◽  
Naida S. Abakarova ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Hydrostatic Pressure ◽  
Magnetic Fields ◽  
Transverse Magnetic Field ◽  
Magnetic Moment ◽  
Transverse Magnetic ◽  
Anomalous Behavior ◽  
Structural Transitions ◽  
Galvanomagnetic Properties ◽  
Magnetic Resistance

The Cd3As2+MnAs composite with 20 mole % of MnAs has been studied complexly in a wide ranges of temperatures, pressures and magnetic fields. Negative magnetic resistance has been found in the sample. This anomalous behavior is considered as a result of changes in tunneling processes due to reduce of distance between magnetic moment of ferromagnetic and structural transitions caused by pressure.

Possible Use of Magnetic Fields in Determining Pore Geometry of Porous Media

1971 ◽  
Vol 11 (03) ◽  
pp. 223-228 ◽  
Author(s):  
C.I. Pierce ◽  
L.C. Headley ◽  
W.K. Sawyer
Keyword(s):  
Magnetic Field ◽  
Porous Media ◽  
Magnetic Fields ◽  
Transverse Magnetic Field ◽  
Field Intensity ◽  
Flow Rate ◽  
Transverse Magnetic ◽  
Conducting Fluid ◽  
Petroleum Reservoir ◽  
The Magnetic Field

Abstract Simplified models, consisting of single, circular channels and channels of different length and diameter in series and parallel combinations, are used in conjunction with the equations of Poiseuille and Hartmann to demonstrate the dependence of the rate of flow of mercury in the models on channel dimensions when the models are subjected to transverse magnetic fields. Experimental tests conducted on mercury-saturated, glass-bead packs and a natural rock sample show that a magnetic field applied transversely to the direction of flow retards flow rate. The magnitude of the magnetic effect increased with increasing bead size and field intensity. Results of this work suggest that magnetic fields have potential in the study of the internal geometry of flow channels in porous media. Introduction The purpose of this work is to determine qualitatively by theoretical and experimental considerations whether or not a magnetic method has potential in the study of the basic properties of rock. The nature of the solid surface and the geometry of the pore network in petroleum-bearing rock plays an important role in the flow behavior of fluids in a petroleum reservoir. Hence, any technique of study that would provide new and additional information on the rock matrix would contribute to a better understanding of petroleum reservoir performance. One such technique appearing to offer performance. One such technique appearing to offer promise is in the area of magnetohydrodynamics. promise is in the area of magnetohydrodynamics. While much research, both theoretical and experimental, has been devoted to the problems concerned with the flow of conducting fluids in transverse magnetic fields in single channels, very little information has been published regarding the behavior of conducting liquids in porous media under the influence of a transverse magnetic field. Perhaps this dearth of information can be attributed Perhaps this dearth of information can be attributed to two main causes:the pores and pore connections are generally so small that intense magnetic fields are required to produce Hartmann numbers of sufficient magnitude to exert appreciable influence on flow rate, andthe extreme complexity of the channel systems in porous media render them intractable to theoretical analysis unless numerous assumptions are made to simplify network geometry. When a conducting fluid moves in a channel in a transverse magnetic field, a force is exerted on the fluid which retards its flow. The magnitude of flow-rate retardation increases with increasing field intensity, channel dimensions and channel-wall conductivity. These magnetohydrodynamic phenomena and theory have been described and developed by various investigators. Since a petroleum reservoir rock is an interconnected network of pores and channels within a rock framework, one would anticipate that the geometry of the network would exert some influence on the magnitude of the effect of a transverse magnetic field on the rate of flow of a conducting fluid therein. The purpose of this work is to demonstrate through the use of simple models and experimental data that the magnetic field effect on flow rate has potential for use in determining size and size potential for use in determining size and size distribution of pores in porous materials. THEORY Electromagnetic induction in liquids is not completely defined, and the complexities involved in many cases appear to defy true analytical expression. However, by applying some simplifying assumptions, these cases may be made tractable to solution to provide qualitative indication of system behavior. The following analysis was conducted in conjunction with laboratory tests to determine if magnet ohydrodynamics has possible potential as a tool for studying the internal geometry of porous systems. When a conducting liquid moves in a channel in a transverse magnetic field, an emf is developed in the channel normal to both the channel axis and the magnetic field. This emf causes circulating currents to flow in the liquid as shown in Fig. 1. SPEJ P. 223

Wake structure of laminar flow past a sphere under the influence of a transverse magnetic field

2019 ◽  
Vol 873 ◽  
pp. 151-173
Author(s):  
Jun-Hua Pan ◽  
Nian-Mei Zhang ◽  
Ming-Jiu Ni
Keyword(s):  
Magnetic Field ◽  
Reynolds Number ◽  
Magnetic Fields ◽  
Transverse Magnetic Field ◽  
Symmetry Plane ◽  
Transverse Magnetic ◽  
Symmetric State ◽  
Wake Structure ◽  
Plane Symmetric ◽  
Double Plane

The wake structure of an incompressible, conducting, viscous fluid past an electrically insulating sphere affected by a transverse magnetic field is investigated numerically over flow regimes including steady and unsteady laminar flows at Reynolds numbers up to 300. For a steady axisymmetric flow affected by a transverse magnetic field, the wake structure is deemed to be a double plane symmetric state. For a periodic flow, unsteady vortex shedding is first suppressed and transitions to a steady plane symmetric state and then to a double plane symmetric pattern. Wake structures in the range $210<Re\leqslant 300$ without a magnetic field have a symmetry plane. An angle $\unicode[STIX]{x1D703}$ exists between the orientation of this symmetry plane and the imposed transverse magnetic field. For a given transverse magnetic field, the final wake structure is found to be independent of the initial flow configuration with a different angle $\unicode[STIX]{x1D703}$. However, the orientation of the symmetry plane tends to be perpendicular to the magnetic field, which implies that the transverse magnetic field can control the orientation of the wake structure of a free-moving sphere and change the direction of its horizontal motion by a field–wake–trajectory control mechanism. An interesting ‘reversion phenomenon’ is found, where the wake structure of the sphere at a higher Reynolds number and a certain magnetic interaction parameter ($N$) corresponds to a lower Reynolds number with a lower $N$ value. Furthermore, the drag coefficient is proportional to $N^{2/3}$ for weak magnetic fields or to $N^{1/2}$ for strong magnetic fields, where the threshold value between these two regimes is approximately $N=4$.

The transverse magnetic field effect on steady-state solutions of the Bursian diode

2015 ◽  
Vol 22 (4) ◽  
pp. 042110 ◽  
Author(s):  
Sourav Pramanik ◽  
A. Ya. Ender ◽  
V. I. Kuznetsov ◽  
Nikhil Chakrabarti
Keyword(s):  
Magnetic Field ◽  
Steady State ◽  
Transverse Magnetic Field ◽  
Field Effect ◽  
Magnetic Field Effect ◽  
Transverse Magnetic ◽  
Steady State Solutions

TWO-DIMENSIONAL ANISOTROPIC HEISENBERG FERROMAGNET IN COEXISTING TRANSVERSE AND LONGITUDINAL MAGNETIC FIELDS

2007 ◽  
Vol 21 (22) ◽  
pp. 3877-3887 ◽  
Author(s):  
AI-YUAN HU ◽  
YUAN CHEN
Keyword(s):  
Magnetic Field ◽  
Magnetic Properties ◽  
Green Function ◽  
Magnetic Fields ◽  
Transverse Magnetic Field ◽  
Transverse Magnetic ◽  
Heisenberg Ferromagnet ◽  
Two Dimensional ◽  
Temperature Anisotropy ◽  
The Green Function

The two-dimensional spin-1/2 anisotropic Heisenberg ferromagnet is investigated in coexisting transverse and longitudinal magnetic fields. Using the Green function treatment, the magnetization and susceptibility are studied as a function of temperature, anisotropy and magnetic fields. The effects of exchange anisotropy and transverse magnetic field on the magnetic properties of the system are discussed.

scholarly journals The Townsend Ionization Coefficients in Crossed Electric and Magnetic Fields

1958 ◽  
Vol 11 (1) ◽  
pp. 18 ◽  
Author(s):  
HA Blevin ◽  
SC Haydon
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Transverse Magnetic Field ◽  
Transverse Magnetic ◽  
Ionization Coefficient ◽  
Electric And Magnetic Fields ◽  
Ionization Coefficients

An expression is obtained for the first Townsend ionization coefficient in uniform crossed electric and magnetic fields, and shown to be in better agreement with observation than previous theoretical expressions. The" equivalent pressure" concept for the effect of a transverse magnetic field on this coefficient is shown to be a valid approach to the problem, although the value for the equivalent pressure obtained in this analysis differs from the values given by earlier authors.

Transient Vibration Analysis of a Pinned Beam With Transverse Magnetic Fields and Thermal Loads

2005 ◽  
Vol 127 (3) ◽  
pp. 247-253 ◽  
Author(s):  
Guan-Yuan Wu
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Transverse Magnetic Field ◽  
Linear Thermal Expansion ◽  
Primary Resonance ◽  
Transverse Magnetic ◽  
Velocity Versus ◽  
Damping Factor ◽  
Thermal Loads ◽  
Transient Vibration

The research investigates the transient vibrations of a pinned beam with transverse magnetic fields and thermal loads. The equation of motion is derived by the Hamilton’s principal, and the damping factor is considered. The property of the material is assumed which has the linear thermal expansion and resistivity. Using the Runge–Kutta method, the amplitude versus time and velocity versus amplitude for the first mode and the first two modes are dertermined. The results show that the transient vibratory behaviors of the beam are influenced by the magnetic fields, thermal loads, and the frequencies of oscillation transverse magnetic field. Also, the period of vibration shifts to higher value with the increase of the magnetic fields and temperatures. In this paper, the effects of using different frequencies of the oscillating transverse magnetic field to display the beat phenomenon and primary resonance are also presented and discussed.

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