scholarly journals Distribution of magnetic field around simply and multiply connected supraconductors

1936 ◽  
Vol 157 (890) ◽  
pp. 132-146 ◽  
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Magnetic Flux ◽  
Meissner Effect ◽  
The Body ◽  
Persistent Current ◽  
Closed Circuit ◽  
Multiply Connected ◽  
Constant Flux ◽  
Connected Body

The experiments to be described in this paper arose from a suggestion by M. von Laue that it would be of interest to examine more closely the behaviour of simply and multiply connected supraconducting bodies in an external magnetic field. If a closed circuit be taken wholly within a supraconducting body, sufficiently far from the surface, the magnetic flux through the circuit should be constant as long as no part of the body is subjected to a magnetic field greater than the critical field strength. For a simply connected body, if the spontaneous ejection of flux on cooling through the transition point, the so-called Meissner effect, is complete, the constant flux through any circuit should be zero. For a multiply connected body, it should be equal to the value immediately after the body became supraconducting. Only in the case of a multiply connected body, that is, a closed circuit, can there be a resultant current through any cross-section in the steady state. This may be taken as a definition of the current I in the circuit, the so-called persistent current. Let L be the self-inductance of the circuit, calculated for the supraconducting state on the assumption that the current flows entirely in a layer very close to the surface. Let ϕ be the calculated magnetic flux through the circuit due to external magnetic field, allowing for the distortion of the field by the presence of supraconducting material. Then, if it can be assumed that the maintenance of the constant flux through the closed circuit is due to a persistent current in the above sense, the law of constant flux can be written in the form LI + ϕ = ϕ 0 . (1)

scholarly journals PERSISTENT SPIN CURRENT AND ENTANGLEMENT IN THE ANISOTROPIC SPIN RING

2007 ◽  
Vol 21 (06) ◽  
pp. 327-337 ◽  
Author(s):  
ZI-XIANG HU ◽  
YOU-QUAN LI
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Magnetic Flux ◽  
Ground State ◽  
State Energy ◽  
Spin Current ◽  
Persistent Current ◽  
One Dimensional ◽  
The Magnetic Field ◽  
Twisted Boundary Conditions

We investigate the ground state persistent spin current and the pair entanglement in one-dimensional antiferromagnetic anisotropic Heisenberg ring with twisted boundary conditions. By solving Bethe ansatz equations numerically, we calculate the dependence of the ground state energy on the total magnetic flux through the ring, and the resulting persistent current. Motivated by the recent development of the quantum entanglement theory, we study the properties of the ground state concurrence under the influence of the flux through the anisotropic Heisenberg ring. We also include an external magnetic field and discuss the properties of the persistent current and the concurrence in the presence of the magnetic field.

scholarly journals Magnetic behaviour of supraconducting tin spheres

1935 ◽  
Vol 151 (873) ◽  
pp. 316-333 ◽  
Author(s):  
K. Mendelssohn ◽  
J. D. Babbitt ◽  
Frederick Alexander Lindemann
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Magnetic Force ◽  
Magnetic Behaviour ◽  
The Body ◽  
Whole Body ◽  
Measured Field ◽  
Lines Of Force ◽  
As If ◽  
Field Strengths

Until a year ago it was generally accepted that if a body is made supraconducting while in a magnetic field the lines of magnetic force were "frozen in," i. e ., whatever lines of force passed through the body at the time when it became supraconducting remained there afterwards, unaffected by any change in the external field, so long as the body was supraconducting. Meissner and Ochsenfeld, however, showed that this supposition was not true. They measured field strengths in the immediate neighbourhood of cylinders which had been cooled to supraconductivity in an external magnetic field, and found that the field of force was then of the same nature as that to be expected in the neighbourhood of perfectly diamagnetic bodies. Thus it appeared that when a body becomes supraconducting in a magnetic field the lines of force are all pressed out of the body, and the induction inside the body falls to zero. At the same time, however, these authors report on another experiment, the result of which appears to us not entirely in accordance with the assumption that the induction in the whole body became zero. They measured the field strengths inside and outside a hollow cylinder, after it had become supraconducting in a field perpendicular to its axis, and found again that the field strength outside was as if the cylinder were almost perfectly diamagnetic, but the field inside was appreciably the same as if the cylinder were non-supraconducting. We therefore made a number of experiments, hoping to find out more exactly the nature of the phenomenon.

scholarly journals Collimation of hot electron beams by external field from magnetic-flux compression

2013 ◽  
Vol 31 (4) ◽  
pp. 579-582 ◽  
Author(s):  
Yuqiu Gu ◽  
Jinqing Yu ◽  
Weimin Zhou ◽  
Fengjuan Wu ◽  
Jian Wang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electron Beam ◽  
External Magnetic Field ◽  
Magnetic Flux ◽  
External Field ◽  
Fast Ignition ◽  
Hot Electrons ◽  
Hot Electron ◽  
Flux Compression ◽  
Magnetic Flux Compression

AbstractIn fast ignition of inertial confinement fusion, hot electron beam is considered to be an appropriate energy source for ignition. However, hot electrons are divergent as they are transporting in over-dense plasma. So collimating the hot electrons becomes one of the most important issues in fast ignition. A method to collimate hot electron beam by external magnetic field is proposed in this paper. The external field can be generated by compressing a seed magnetic field at the stage of laser-driven implosion. This method is confirmed by particle-in-cell simulations. The results show that hot electrons are well collimated by external magnetic field from magnetic-flux compression.

The Thermoelectric-Hydromagnetic Pump

1964 ◽  
Vol 86 (2) ◽  
pp. 166-168 ◽  
Author(s):  
J. F. Osterle ◽  
S. W. Angrist
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Magnetic Flux ◽  
Flux Density ◽  
Pressure Rise ◽  
Maximum Efficiency ◽  
Magnetic Flux Density ◽  
Optimum Thickness ◽  
Pumping Power ◽  
Electrically Conducting

A thermally powered pump for fluids which are electrically conducting, which utilizes the Lorentz force between an electric current induced by the Seebeck effect, and an external magnetic field is examined. The pressure rise in the pump is found to be proportional to the magnetic flux density while the flow rate is found to be inversely proportional to the magnetic flux density. Thus the pumping power and efficiency (both being proportional to the product of pressure rise and flow) are independent of the applied magnetic field. Calculations for a pump with constantan walls handling sodium and utilizing a temperature difference of 300 deg C show that a maximum efficiency of close to seven-tenths of a percent is possible. If the same pump is constructed with optimum thickness walls made of the semiconductor AgSbTe2, it would have an efficiency of nearly six percent.

SURFACE BARRIER IN THE MIXED STATE OF ANISOTROPIC SUPERCONDUCTOR

1993 ◽  
Vol 07 (12) ◽  
pp. 841-847
Author(s):  
T. KRZYSZTON
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Magnetic Flux ◽  
Flux Density ◽  
Magnetic Flux Density ◽  
Surface Barrier ◽  
Anisotropy Axis ◽  
Anisotropic Superconductor ◽  
Applied External Magnetic Field ◽  
London Theory

In the framework of London theory, the problem of equilibrium between magnetic flux density in the anisotropic superconductor and the applied external magnetic field is studied. The Gibbs free energy of a fluxoid in the presence of magnetic flux density in the sample is calculated. As a result, critical entry and exit fields are calculated and their dependence upon the angle which makes anisotropy axis and the direction of an external magnetic field.

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