Magnet, Superconducting

Fusion Magnets SMES Turtrogenerators I NMR Tomography Magnetic Seperators I Power Transmission Lines 

When a superconductor in its normal (i.e., nonsuper-conducting) state is placed in a magnetic field and then cooled below its critical temperature the induced magnetization, M, exactly opposes H and so from Eq. 33.3, we can write 

Although there is no magnetic field in the bulk of a superconductor it does penetrate below the surface to a depth of between 0.2 and 0.8 pm. 

These values are enormous. The world s most pow erful magnet is about 40 T  

TABLE 33.4 Magnetic Susceptibilities for Severai Diamagnetic Materials 

There is an upper limit to the strength of the magnetic field that can be applied to a superconductor without changing its diamagnetic behavior. At a critical field the magnetization goes toward zero and the material reverts to its normal state. For most elemental superconductors M rises in magnitude up to and then abruptly drops to zero this is Type I behavior. 

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Figure Bl.l 1.2. Simplified representation of an NMR spectrometer with pulsed RF and superconducting magnet. The main magnetic field Bq is vertical and centred on the sample.

It is used in arc-welding rods for stabilized grades of stainless steel. Thousands of pounds of niobium have been used in advanced air frame systems such as were used in the Gemini space program. The element has superconductive properties superconductive magnets have been... 

Fig. 3. A block diagram schematic representation of a Fourier transform nmr spectrometer, ie, a superconducting magnetic resonance system.

Fig. 22. Superconducting magnet configurations for MHD generators where the arrows represent the magnetic lines of force, (a) Solenoid (b) racetrack ...

Consortium/ Ansaldo CNR/ Ansaldo Geneva 5 T, 62 M MHD superconducting magnet under constmction... 

HTS materials, because of their ceramic nature, are quite brittle. This has introduced problems relative to the winding of superconducting magnets. One solution is to first wind the magnet with the powder-in-tube wire before the ceramic powder has been bonded and then heat treat the desired configuration to form the final product. Another solution is to form the superconductor into such fine fila-... 

FIO. 19-53 Basic process cycle for a reciprocating canister superconducting magnetic separator. (Couttesy Carpco, Inc.)... 

Other specialized uses of Sn and its alloys are as type metal, as the molten-metal bath in the manufacture of float glass and as the alloy NbsSn in superconducting magnets. The many industrial and domestic uses of tin compounds are discussed in later sections these compounds account for about 15% of the tin produced worldwide. 

Niobium finds use in the production of numerous stainless steels for use at high temperatures, and Nb/Zr wires are used in superconducting magnets. The extreme corrosion-resistance of tantalum at normal temperatures (due to the presence of an exceptionally tenacious film of oxide) leads to its application in the construction of chemical plant, especially where it can be used as a liner inside cheaper metals. Its complete inertness to body fluids makes it the ideal material for surgical use in bone repair and internal suturing. 

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