Abstract:
A cryogenically-cooled superconducting RF head-coil array which may be used in whole-body MRI scanners and/or in dedicated, head-only MRI systems. A superconducting main magnet system for a head-dedicated MRI system is also provided, and a head-only MRI system may comprise such a superconducting main magnet and a cryogenically-cooled superconducting RF head-coil array.
Abstract:
A transmit/receive switch of a nuclear magnetic resonance apparatus includes receive-path and transmit- path superconductors, which are selectively quenched to switch the connection of an NMR radio-frequency coil between transmit and receive circuits. In the transmit state, the transmit- path superconductor is in a superconducting state while the receive-path superconductor is quenched, to isolate a receive-path amplifier from the relatively higher powers of the NMR pulses applied to the sample by the ' transmit circuit. In the receive state, the receive-path superconductor is in a superconducting state while the transmit-path superconductor is quenched. A DC power source is used to supply supercritical current to the superconductors to quench the superconductors.
Abstract:
The methods of the invention for scanning a band of frequencies using a nuclear quadrupole resonance detection system with an array of high temperature superconductor sensors to detect nuclear quadrupole resonance signals improve the nuclear quadrupole resonance detection system performance.
Abstract:
Le système de mesure d'un signal de résonance magnétique au sein d'un échantillon (4) placé dans un champ magnétique extérieur statique (H), comprend un dispositif d'excitation (1 à 3, 6 à 10) pour appliquer des impulsions radiofréquence de forte intensité à une fréquence d'émission prédéterminée fe dans une zone de mesure contenant l'échantillon (4). Le dispositif d'excitation comprend une bobine d'excitation (3) raccordée à la fréquence d'émission prédéterminée fe et disposée au voisinage de l'échantillon (4) de manière à émettre un champ électromagnétique essentiellement perpendiculaire au champ magnétique extérieur statique (H). Le système comprend en outre au moins un capteur hybride supraconducteur-magnétorésistif (5) comprenant une boucle supraconductrice munie d'une constriction apte à augmenter significativement la densité du courant et au moins un capteur magnétorésistif placé à proximité immédiate de la constriction, en étant séparé de celle-ci par un dépôt isolant.
Abstract:
The use of a superconducting resonator with continuous-wave (CW) excitation allows low-noise quadrupole resonance (QR) detection without the need for a lock-in amplifier. This allows detection times to be greatly reduced. Hence, for the first time, a CW QR spectrometer using a superconducting resonator can be used in a portable device, such as a hand-held wand for detecting explosives.
Abstract:
The methods of the invention for scanning a band of frequencies using a nuclear quadrupole resonance detection system with an array of high temperature superconductor sensors to detect nuclear quadrupole resonance signals improve the nuclear quadrupole resonance detection system performance.
Abstract:
The frequency of the fundamental symmetric mode of two or more coupled essentially identical high temperature superconductor coils can be tuned, with little degradation in Q, by mechanically displacing the two or more coils with respect to one another. These coupled coils are useful in a detection system for detecting frequencies.
Abstract:
A double tuned probe for employment in NMR apparatus includes a first resonant circuit of normal phase conductor coupled to the sample and also in communication with a second circuit containing a component in a superconductive phase. Communication between the two circuits supports two RF channels which may be exhibit relative sensitivities in proportion to their relative Q values.
Abstract:
A double tuned probe for employment in NMR apparatus includes a first resonant circuit of normal phase conductor coupled to the sample and also in communication with a second circuit containing a component in a superconductive phase. Communication between the two circuits supports two RF channels which may be exhibit relative sensitivities in proportion to their relative Q values.