Meissner-Ochsenfeld effect

The applications of superconducting materials can be summarized in two main categories high-magnetic-field and low-magnetic-field applications. 

Low-magnetic-field applications. These applications include Josephson-effect devices, magnetic-flux shields, transmission fines, and resonant cavities, all of which require superconducting materials having a high critical temperature and a high critical magnetic field. 

ASTM Standard B713-82 (1997) Standard Terminology Relating to Superconductors. In The Annual Book of ASTM Standard Vol. 02.03, pp.346-348. 

(1989) Engineer s Guide to High-Temperature Superconductivity. Wiley, New York. 

Schwartz, B.B. (1981) Superconductor Materials Science Metallurgy, Fabrication and Applications. Plenum, New York. 

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Demonstration of the Meissner-Ochsenfeld Effect A Hovering Superconductor... 

Meissner, Walther (1882-1974) and his graduate student Robert Ochsenfeld (1901-1993), both Germans working in Berlin, discovered in 1933 that a superconducting material repels a magnetic field— behaving as a perfect diamagnet. The effect became known as the Meissner (or Meissner-Ochsenfeld) effect... 

In 1935, Fritz and Heinz London (London and London, 1935) provided a first phenomenological approach to the theory of superconductivity. Using the concept of a superelectron with twice the electron s mass and charge, the London equations described very well the properties of a superconductor that is, its infinite electric conductivity as well as the decay of the magnetic field in a thin surface layer of a superconductor (the Meissner-Ochsenfeld effect) (see Appendix E). 

In the classical model of superconductivity, the London equations (London and London 1935) are equivalent to Ohm s law j = o-E for a normal electric conductor. The first of the London equations [Eq. (E.l)] represents a conductor with R = 0, while the second [Eq. (E.2)] is equivalent to the Meissner-Ochsenfeld effect (Figure E.l), and describes the decay of a magnetic field within a thin surface layer characterized by the penetration depth,... 

Meissner-Ochsenfeld effect of magnetic flux expulsion below (created by Piotr (aworski, Poznan, Poland) (b) The energy gap 2A of a superconductor. The electronic states of a normal electrically conducting metal are filled... 

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