Superconducting coils

Figure Bl.l 1.2 represents the essential components of a modem high-resolution NMR spectrometer, suitable for studies of dissolved samples. The magnet has a superconducting coil in a bath of liquid Fie, jacketed by...

MSB current density map over a predefined magnet domain, where superconducting coils will be laid out, subject to constraints, such as the homogeneity of the FOV and footprint of the magnet stray field. 

Figures 4E, 5E, 6E and 7E depict the individual coil hoop stresses along the radial direction at the middle plane of each coil. Particularly for the high-field 11.75T magnet, the stress calculation indicates that the most inner coils are the ones that are most crucial in the design, because they are exposed to the greatest magnetic fields and sfresses. If is possible to use different superconductors (i.e. cheaper) to build the outer superconducting coils, since these are well within the superconductivity limit.

J. Caldwell, Magnetostatic field calculcations associated with superconducting coils in the presence of magnetic material. IEEE Trans. Magn., 1982,18(2), 397-400. 

Figure 9.29—NM R magnets and samples. Robotic introduction (on the left) of a sample in solution placed in an NMR tube within a magnetic field generated by a superconducting coil and maintained at liquid helium temperature. (Reproduced by permission of Varian.) Electromagnet ton the right) of sizeable volume used for a special kind of sample the human body (part of an MRI instrument from the SMIS Society).

Shelving spectroscopy thus involves many decisions whether the antihydrogen atom has been excited to the metastable 2 2S /2 state or not. These decisions have to be made somewhat quicker than the natural lifetime of the metastable state and are based on the observation or the non-observation of fluorescent light at Lyman-a. The detection efficiency for fluorescent light from an antihydrogen sample in a magnetic trap with superconducting coils is probably rather... 

The trapping field is similar to that discussed by Pritchard [18] and Hess[7] and is generated by a superconducting coil system operated during the measurements in persistent mode. For radial confinement we use four racetrack shaped coils which provide a quadrupole field. At maximum current (36 A) the quadrupole field reaches 1.4-1.5 Tesla at r-6.5mm, the surface of the sample cell. Two dipole fields are used for axial confinement. They are located near the ends of the racetracks at z- +50mm and z--50mm with respect to the center of the trap. 

Sensor system uses superconducting coils to measure the brain s magnetic fields. (Drawing courtesy of Samuel Williamson, New York University.)... 

Bremsstrahlung and synchrotron radiation emitted during operation are absorbed in the walls of the vessel, which must be cooled. Very good heat insulation is required between the hot walls of the vessel ( 1000 °C) and the superconducting coils of the magnets ( 5K). 

The central cylindrical section surrounded by magnetic field coils will be long, possibly as long as 100 meters. The surface of the cylinder will be fabricated with channels to carry the liquid metal coolant. Each end of the cylindrical section would be fitted with an electrostatic/ magnetic end cap to prevent excess leakage of the plasma from the ends. The magnetic field used to confine the plasma would rely on superconducting coils to minimize the power required to sustain the confinement fields. 

Figure 15.25 Sample introduction for NMR spectrometers. Left, automatic introduction of a sample placed in an NMR tube within the magnetic field produced by a superconducting coil maintained at liquid helium temperature (reproduced courtesy of Varian). Right, a large magnet employed for the introduction of a particular kind of sample - the human body (part of a MRI instrument from SMIS).

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