SELECTIVE EXCITATION OF COILS COMPRISING A SUPERCONDUCTING MAGNET

Thermal isolation of a cryostat is improved for a superconducting solenoid having a plurality of separately energizable coils or winding sections by reducing the number of conductors required to selectively energize the persistence switch controlling a particular winding section. As a consequence, the dimensions of the vent and fill tube openings of the cryostat which accomodate these conductors may be reduced. In one embodiment a diode is incorporated in series with heating element of each switch. The switches are connected ?o form a steering network to control as many as p?n(n-1) separate coils using n conductors to actuate p persistence switches. In another embodiment n(n-1)/2 coils are similarly controlled with n conductors using the time-current response of persistence switches without diodes. Still another embodiment utilizes a binary to hexadecimal converter within the cryostat to permit n externally generated signal conductor to select as many as p ? 2? -1 persistence switches.

CRYOSTAT WITH EXTERNAL REFRIGERATOR FOR SUPERCONDUCTING NMR SPECTROMETER

PATENT APPLICATION of GEORGE D. KNEIP, JR. AND MARVIN H. ANDERSON for IMPROVED CRYOSTAT WITH EXTERNAL REFRIGERATOR FOR SUPERCONDUCTING NMR SPECTROMETER Abstract of Disclosure An improved cryostat for the superconducting magnet of an NMR spectrometer comprises a nested structure of isothermal shells surrounding a thermally conductive central reservoir of substantially spherical shape containing liquid helium in which the superconducting solenoid remains operational when only partially immersed. A radiation shield surrounding the central reservoir is cooled by the boil-off of escaping helium vapor. The radiation shield is enclosed within an isothermal shell maintained at the temperature of liquid nitrogen by thermal contact with a liquid nitrogen reservoir disposed above the region of the central reservoir and shielded therefrom by a wall of the isothermal shell. An outer radiation shield surrounds the liquid nitrogen reservoir and associated isothermal shell and the outer radiation shield is maintained at a temperatures of the order of 180°K by an external refrigeration facility. A hermitically sealed containment vessel forms the outer wall of the cryostat and provides a port for evacuating to a very low common pressure all the interior spaces between adjacent nested structures. The spacing between adjacent nested surfaces is maintained by a novel internal mechanical bracing system of low thermal conductivity comprising polyester cords disposed under tension between adjacent shells. -i-

SUPERCONDUCTING ALLOYS

CRYOSTAT WITH REFRIGERATOR FOR SUPERCONDUCTION NMR SPECTROMETER

PATENT APPLICATION of GEORGE D. KNEIP, JR. AND MARVIN H. ANDERSON for IMPROVED CRYOSTAT WITH EXTERNAL REFRIGERATOR FOR SUPERCONDUCTING NMR SPECTROMETER An improved cryostat for the superconducting magnet of an NMR spectrometer comprises a nested structure of isothermal shells surrounding a thermally conductive central reservoir of substantially spherical shape containing liquid helium in which the superconducting solenoid remains operational when only partially immersed. A radiation shield surrounding the central reservoir is cooled by the boil-off of escaping helium vapor. The radiation shield is enclosed within an isothermal shell maintained at the temperature of liquid nitrogen by thermal contact with a liquid nitrogen reservoir disposed above the region of the central reservoir and shielded therefrom by a wall of the isothermal shell. An outer radiation shield surround the liquid nitrogen reservoir and associated isothermal shell and the outer radiation shield is maintained at a temperature ...

CRYOSTAT FOR SUPERCONDUCTING NMR SPECTROMETER

PATENT APPLICATION of GEORGE D. KNEIP, JR. for IMPROVED CRYOSTAT WITH EXTERNAL REFRIGERATOR FOR SUPERCONDUCTING NMR SPECTROMETER Abstract of the Disclosure An improved cryostat for the superconducting magnet of an NMR spectrometer comprises a nested structure of isothermal shells surrounding a thermally conductive central reservoir of substantially spherical shape containing liquid helium in which the superconducting solenoid remains operational when only partially immersed. A radiation shield surrounding the central reservoir is cooled by the boil-off of escaping helium vapor. The radiation shield is enclosed within an isothermal shell maintained at the temperature of liquid nitrogen by thermal contact with a liquid nitrogen reservoir disposed above the region of the central reservoir and shielded therefrom by a wall of the isothermal shell. An outer radiation shield surrounds the liquid nitrogen reservoir and associated isothermal shell and the outer radiation shield is maintained at a temperatures of the order of 235° K by vapor cooling from the boil-off of escaping forms the outer wall of the cryostat sealed containment vessel forms the outer wall of the cryostat and provides all the interior spaces between adjacent nested structures. 2chb21778 -1- 78-08

METHOD FOR INCREASING THE CRITICAL CURRENT OF SUPERCONDUCTING ALLOYS

SUPERCONDUCTING SWITCH INCORPORATING A STEERING DIODE

A persistence switch comprises a diode and superconductive wire in thermal contact with the diode. The heat evolved by current through the forward biased diode raises the temperature of the superconductor above the transition temperature. The diode chracteristic of the switch permits a plurality of such switches to be arranged in a network for selection by a relatively few signal conductors.

LOW EMISSIVITY LIQUID NITROGEN DEWAR

PATENT APPLICATION of GEORGE D. KNEIP, JR., GEORGE CHMYZ and MARVIN H. ANDERSON for LOW EMISSIVITY LIQUID NITROGEN DEWAR FOR CRYOGENIC LIQUIDS A Dewar for liquified gases includes a spun can for the liquified gas, which spun can is surrounded by an exterior shell. Between the exterior shell and the can is an evacuated space containing a second shell that functions as a radiation shield. The can and both shells are formed of an aluminum alloy havng a very high percentage of aluminum. The exterior can surface, interior surface of the exterior shell, and both surfaces of the second shell have clean, non-pitted, smooth, matted, smut free and etched appearances free from discoloration and stains so that these surfaces have low radiation emissivity properties and there is a minimum amount of radiant energy transmitted from the exterior shell to the can and reduced heating of the liquid nitrogen in the can. Each of the surfaces is initially polished, either mechanically, electrochemically or chemically ...

Apparatus for magnetic field homogenization

An NMR instrument incorporating a cryogenic (23) magnet includes a constant pressure device (32) to main­tain the pressure of cryogenic vapors at a constant value whereby a stable magnetic environment is maintained.

NMR Spectrometer with superconducting coil having rectangular cross-section wire

An NMR spectrometer includes a superconducting, solenoid coil formed of superconducting wire having a rectangular cross-section. The wire is formed of a non superconducting metal surrounding superconducting material having a small enough cross sectional area that a magnetic field resulting from current flowing in the superconductor material has a relatively constant position relative to the cross section of the wire. In one embodiment, the wire has a monofilament configuration including a core of the superconducting material surrounded by a sheath of the metal. In a second embodiment, the wire includes a copper block of the metal through which a multiplicity of superconductive strands extend.

Procédé pour l'accroissement du courant critique dans les alliages supraconducteurs