Characteristics of the Flow of an Ionized Perfect Gas Through a Magnetic Field

1962 ◽  
Vol 29 (3) ◽  
pp. 568-574
Author(s):  
E. N. Carabateas ◽  
G. N. Hatsopoulos
Keyword(s):  
Magnetic Field ◽  
Heat Dissipation ◽  
Perfect Gas ◽  
Flow Equations ◽  
Isentropic Flow ◽  
Magnetic Field Region ◽  
Scalar Constant ◽  
Fractional Ionization ◽  
The Difference ◽  
The Magnetic Field

The problem of the compressible flow of a perfect gas with constant fractional ionization through a magnetic field is considered. The Joulean heat dissipation is assumed to be taken out of the gas so that the flow can be treated as isentropic. The present analysis differs slightly from others previously reported in the literature [1, 2, 3, 4] mainly in that the entire conductivity tensor and the variation of its elements with gas properties are taken into account. It is felt that the somewhat unrealistic condition of isentropic flow is much less restrictive than the assumption of a scalar constant conductivity. Under these conditions, a relatively simple integration of the flow equations is possible. The assumption of isentropic flow implies that the difference in stagnation enthalpies at the entrance and exit of the magnetic field region is equal to the electrical output plus the Joulean heat. Therefore the ratio of the output power to the difference in stagnation enthalpies gives a measure of the Joulean heat dissipation and hence of the efficiency of the device.

scholarly journals First in-orbit results of the vector magnetic field measurement of the High Precision Magnetometer onboard the China Seismo-Electromagnetic Satellite

2019 ◽  
Vol 71 (1) ◽  
Author(s):  
Bin Zhou ◽  
Bingjun Cheng ◽  
Xiaochen Gou ◽  
Lei Li ◽  
Yiteng Zhang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Precision ◽  
Magnetic Field Measurement ◽  
Vector Data ◽  
Magnetic Field Data ◽  
Night Side ◽  
The Difference ◽  
The Magnetic Field ◽  
Ground Calibration ◽  
Data Calibration

Abstract The High Precision Magnetometer (HPM) is one of the main payloads onboard the China Seismo-Electromagnetic Satellite (CSES). The HPM consists of two Fluxgate Magnetometers (FGM) and the Coupled Dark State Magnetometer (CDSM), and measures the magnetic field from DC to 15 Hz. The FGMs measure the vector components of the magnetic field; while the CDSM detects the magnitude of the magnetic field with higher accuracy, which can be used to calibrate the linear parameters of the FGM. In this paper, brief descriptions of measurement principles and performances of the HPM, ground, and in-orbit calibration results of the FGMs are presented, including the thermal drift and magnetic interferences from the satellite. The HPM in-orbit vector data calibration includes two steps: sensor non-linearity corrections based on on-ground calibration and fluxgate linear parameter calibration based on the CDSM measurements. The calibration results show a reasonably good stability of the linear parameters over time. The difference between the field magnitude calculated from the calibrated FGM components and the magnitude directly measured by the CDSM is just 0.5 nT (1σ) when the linear parameters are fitted separately for the day- and the night-side. Satellite disturbances have been analyzed including soft and hard remanence as well as magnetization of the magnetic torquer, radiation from the Tri-Band Beacon, and interferences from the rotation of the solar wing. A comparison shows consistency between the HPM and SWARM magnetic field data. Observation examples are introduced in the paper, which show that HPM data can be used to survey the global geomagnetic field and monitor the magnetic field disturbances in the ionosphere.

The Magnetic Anisotropy of Stretched Rubber as a Function of the Tension to Which It Is Subjected

1945 ◽  
Vol 18 (1) ◽  
pp. 8-9 ◽  
Author(s):  
Eugénie Cotton-Feytis
Keyword(s):  
Magnetic Field ◽  
Magnetic Anisotropy ◽  
Uniaxial Crystal ◽  
Horizontal Magnetic Field ◽  
First Approximation ◽  
The Difference ◽  
The Times ◽  
Angular Displacements ◽  
The Magnetic Field ◽  
Oscillation Method

Abstract From the standpoint of its magnetic anisotropy, stretched rubber is comparable in a first approximation to a uniaxial crystal, in which the direction of the axis is the same as the direction of elongation. It is possible to measure this anisotropy by means of the oscillation method used by Krishnan, Guha and Banerjee in studying crystals. The sample to be examined is suspended in a uniform horizontal magnetic field in such a manner that its axis is horizontal. It is then so arranged that the torsion of the suspension wire is zero when the rubber sample is in a position of equilibrium in the field. The times of oscillation T′ and T for very small angular displacements around this position, in the presence and then in the absence of the magnetic field, are then recorded. In this way the difference between the specific susceptibilities in the direction of the axis and in the horizontal direction perpendicular to the axis is calculated by application of the equation:

Effect of a static magnetic field onEscherichia coliadhesion and orientation

2016 ◽  
Vol 62 (11) ◽  
pp. 944-952 ◽  
Author(s):  
Lotfi Mhamdi ◽  
Nejib Mhamdi ◽  
Naceur Mhamdi ◽  
Philippe Lejeune ◽  
Nicole Jaffrezic ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Tin Oxide ◽  
Indium Tin Oxide ◽  
Bacterial Adhesion ◽  
Parallel Magnetic Field ◽  
Field Orientation ◽  
Static Magnetic Fields ◽  
Preliminary Study ◽  
The Difference ◽  
The Magnetic Field

This preliminary study focused on the effect of exposure to 0.5 T static magnetic fields on Escherichia coli adhesion and orientation. We investigated the difference in bacterial adhesion on the surface of glass and indium tin oxide-coated glass when exposed to a magnetic field either perpendicular or parallel to the adhesion surface (vectors of magnetic induction are perpendicular or parallel to the adhesion surface, respectively). Control cultures were simultaneously grown under identical conditions but without exposure to the magnetic field. We observed a decrease in cell adhesion after exposure to the magnetic field. Orientation of bacteria cells was affected after exposure to a parallel magnetic field. On the other hand, no effect on the orientation of bacteria cells was observed after exposure to a perpendicular magnetic field.

V.—Dissymmetrical Separations in the Zeeman Effect in Tungsten and Molybdenum

1909 ◽  
Vol 29 ◽  
pp. 75-83 ◽  
Author(s):  
Robert Jack
Keyword(s):  
Magnetic Field ◽  
Wave Length ◽  
Zeeman Effect ◽  
Normal Type ◽  
Single Spectrum ◽  
Large Numbers ◽  
Middle Component ◽  
The Absolute ◽  
The Difference ◽  
The Magnetic Field

It has been mentioned by Professor Voigt of Göttingen in his newly published book and by Professor Zeeman of Amsterdam in the Physikalische Zeitschrift, that I have found examples of strongly marked dissymmetry in studying the Zeeman Effect in tungsten and molybdenum. Professor Zeeman has also discovered and published such cases of dissymmetry in other elements. Not only have many examples of normal dissymmetry been found, but almost as many cases of abnormal dissymmetry. To explain those terms, normal and abnormal, let us consider that the single spectrum line is broken up, when the light is in the magnetic field, into the three components, 1, 2, 3, where the numbers begin from the component which has the shortest wave-length. In the normal dissymmetrical triplet the middle component is nearer the component on the red side than that on the violet one, i.e. for the normal type the interval 1–2 is greater than the interval 2–3, but in the abnormal dissymmetrical triplet 2 is nearer to 1 than to 3. These observations of Professor Zeeman and myself, which were made at the same time in the Universities of Amsterdam and Göttingen, having been communicated to Professor Voigt, he wrote and published in the above-mentioned book an extension to his and Professor H. A. Lorentz's theories of the Zeeman Effect. In his original theory Professor Voigt had shown that, considering the electrons as uncoupled, cases of normal dissymmetry might arise among the Zeeman triplets, this dissymmetry being accompanied by a greater intensity of the red component than the violet one. He pointed out also that the ‘absolute’ dissymmetry or the difference between the absolute displacements of the red and violet components should be independent of the magnetic field strength used to produce the Zeeman Effect. To explain the large numbers of complicated types of Zeeman Effect which have been found —in the study of the Zeeman Effect in tungsten I discovered lines with no fewer than 17 to 19 components, the largest numbers hitherto found—Professors Voigt and Lorentz made use in their theories of couplings between electrons of the same vibration frequencies.

Characteristics of Magneto-Rheological Elastomer under Stick-Slip Condition

2020 ◽  
Vol 842 ◽  
pp. 193-198
Author(s):  
Kwang Hee Lee ◽  
Chul Hee Lee
Keyword(s):  
Magnetic Field ◽  
Glass Plate ◽  
Static Friction ◽  
Low Noise ◽  
Friction Behavior ◽  
Stick Slip ◽  
The Difference ◽  
Magneto Rheological ◽  
Squeal Noise ◽  
The Magnetic Field

This paper examines the characteristics of stick-slip phenomena between the glass plate and Magneto-Rheological Elastomer (MRE) surface. Stick-slip phenomena are the spontaneous jerking motion that occurs while two objects are sliding over each other, usually accompanied by noise. Stick-slip is generated when it involves discontinuous frictional degradation when moving from static friction to dynamic friction. The phenomena can lead to uneven wear patterns, vibration and squeal noise which cause a shorter lifespan for the corresponding mechanical elements. MREs are kind of function materials to consist of a polymeric matrix with embedded ferromagnetic particles. Mechanical properties of the MREs can be controlled by the application of magnetic fields. The magnetic field-based controllability can be applied to the control of stick-slip phenomena. The friction experiment is conducted with the Reciprocating Friction Tester (RFT). The sliding speed of the RFT should be in low-speed conditions in order to make the stick-slips relatively easy to occur. A uniform magnetic field and a weight load are applied to the MRE sample to observe the effect of various experimental parameters on the movement of the stick-slip. In addition, frictional sounds due to the stick-slip phenomenon under different loads and magnetic field strength are measured and analyzed. The results of this experiment show that as the strength of the magnetic field increases, the difference in stiffness between the wipers-glass decreases, mitigating fricatives. The result is expected to be well applied to low-noise automotive wipers based on the controllability of friction behavior and squeal noise.

On the spontaneous magnetic field in a conducting liquid in turbulent motion

1950 ◽  
Vol 201 (1066) ◽  
pp. 405-416 ◽  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Energy ◽  
Turbulent Motion ◽  
Small Scale ◽  
Flow Equations ◽  
Metallic Conductor ◽  
Set Up ◽  
The Stability ◽  
The Magnetic Field

Several recent investigations in geophysics and astrophysics have involved a consideration of the hydrodynamics of a fluid which is a good electrical conductor. In this paper one of the problems which seem likely to arise in such investigations is discussed. The fluid is assumed to be incompressible and in homogeneous turbulent motion, and externally imposed electric and magnetic fields are assumed to be absent. The equations governing the interaction of the electromagnetic field and the turbulent motion are set up with the same assumptions as are used to obtain the Maxwell and current flow equations for a metallic conductor. It is shown that the equation for the magnetic field is identical in form with that for the vorticity in a non-conducting fluid; immediate deductions are that lines of magnetic force move with the fluid when the conductivity is infinite, and that the small-scale components of the turbulence have the more powerful effect on the magnetic field. The first question considered is the stability of a purely hydrodynamical system to small disturbing magnetic fields, and it is shown that the magnetic energy of the disturbance will increase provided the conductivity is greater than a critical value determined by the viscosity of the fluid. The rate of growth of magnetic energy is approximately exponential, with a doubling time which can be simply related to the properties of the turbulence. General mechanical considerations suggest that a steady state is reached when the magnetic field has as much energy as is contained in the small-scale components of the turbulence. Estimates of this amount of energy and of the region of the spectrum in which it will lie are given in terms of observable properties of the turbulence.

scholarly journals Shape of a slowly rotating star measured by asteroseismology

2016 ◽  
Vol 2 (11) ◽  
pp. e1601777 ◽  
Author(s):  
Laurent Gizon ◽  
Takashi Sekii ◽  
Masao Takata ◽  
Donald W. Kurtz ◽  
Hiromoto Shibahashi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Rotation Period ◽  
Solar Radius ◽  
Spherically Symmetric ◽  
Convective Envelope ◽  
Stellar Radius ◽  
Nearby Stars ◽  
The Difference ◽  
Rotating Star ◽  
The Magnetic Field

Stars are not perfectly spherically symmetric. They are deformed by rotation and magnetic fields. Until now, the study of stellar shapes has only been possible with optical interferometry for a few of the fastest-rotating nearby stars. We report an asteroseismic measurement, with much better precision than interferometry, of the asphericity of an A-type star with a rotation period of 100 days. Using the fact that different modes of oscillation probe different stellar latitudes, we infer a tiny but significant flattening of the star’s shape of ΔR/R = (1.8 ± 0.6) × 10−6. For a stellar radius R that is 2.24 times the solar radius, the difference in radius between the equator and the poles is ΔR = 3 ± 1 km. Because the observed ΔR/R is only one-third of the expected rotational oblateness, we conjecture the presence of a weak magnetic field on a star that does not have an extended convective envelope. This calls to question the origin of the magnetic field.

scholarly journals ERROR IN MEASURING THE MAGNETIC LIQUID MAGNETIZATION BY THE NUCLEAR MAGNETIC RESONANCE, CAUSED BY THE UNCERTAINTY OF THE EFFECTIVE FIELD CONSTANT

2021 ◽  
Vol 57 ◽  
pp. 15-18
Author(s):  
Alexander I. Zhernovoy ◽  
◽  
Ilya A. Yakimenko ◽  
Keyword(s):  
Magnetic Field ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Effective Field ◽  
Magnetic Liquid ◽  
Different Shapes ◽  
The Difference ◽  
The Magnetic Field

The magnetic liquid magnetization is usually determined by measuring the magnetic field strength, which linearly depends on the effective field constant of the liquid and the demagnetization coefficient of the sample. The article proposes to measure the magnetic field strength, generated by the same magnetic liquid in the samples of different shapes, and to determine the magnetization relying on the difference in strength, generated by the samples of various shapes, taking advantage of the fact that the effective field constant does not depend on the shape of the sample

scholarly journals Changes with Height of Longitudinal Magnetic Field in Active Regions

1993 ◽  
Vol 141 ◽  
pp. 24-31
Author(s):  
S.I. Gopasyuk
Keyword(s):  
Magnetic Field ◽  
Field Intensity ◽  
Longitudinal Magnetic Field ◽  
Magnetic Field Intensity ◽  
Transverse Electric ◽  
Active Regions ◽  
Line Profiles ◽  
Current Value ◽  
The Difference ◽  
The Magnetic Field

Results of a study of longitudinal magnetic fields in active regions are presented. The observed magnetic field strength increases with height in the photosphere. The maximum of the magnetic field intensity coincides with the level where the central parts of λ5324,2 Å FeI and λ5269,5 FeI line profiles are formed. On the Hβ formation level the observed magnetic field intensity is smaller as compared with the potential one calculated on the basis of the observed field in FeI λ5253, 5Å line. The difference between the observed magnetic field and potential one is explained in terms of transverse electric currents. The current value can mount to 3×1011 A.

scholarly journals Transfer of continuum UV radiation inside fragmented clouds

1991 ◽  
Vol 147 ◽  
pp. 394-395
Author(s):  
P. Boisse
Keyword(s):  
Magnetic Field ◽  
Fine Structure ◽  
Energy Balance ◽  
Line Emission ◽  
Photoelectric Effect ◽  
Interstellar Clouds ◽  
Governing Factor ◽  
Structure Line ◽  
Fractional Ionization ◽  
The Magnetic Field

The penetration of visible and UV continuum radiation is a governing factor for many processes inside interstellar clouds. It determines for instance: 1) the overall chemical equilibrium (formation/destruction of molecules and neutral or ionized species, fractional ionization of the gas which is directly related to the coupling with the magnetic field); 2) the overall energy balance (heating of the dust, heating of the gas through collisions with electrons extracted from grains by the photoelectric effect or with grains; 3) cooling of the gas due to fine structure line emission (OI,CI,CII).

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