Abstract: A current lead arrangement for supplying current to a superconducting magnet coil, comprising a current lead and a cryogenic refrigerator. The current lead comprises a first section of low temperature superconductor (LTS) wire, joined to a second section of a high temperature superconductor (HTS) material, in turn joined to a third section of a resistive material. The cryogenic refrigerator comprises a first cooling stage and a second cooling stage. A lower end of the third section and an upper end of the second section are thermally linked to the first cooling stage, a lower end of the first section is thermally and electrically connected to the superconducting magnet coil.

Abstract: A method of operating a magnetic resonance imaging (MRI) apparatus includes exciting a body coil of the MRI apparatus to emit a radio-frequency signal, determining a center frequency of a resonance curve of the body coil, and calculating a magnet target frequency based on the determined center frequency. A magnet is ramped to the magnet target frequency.

Abstract: A method of operating a magnetic resonance imaging (MRI) apparatus includes exciting a body coil of the MRI apparatus to emit a radio-frequency signal, determining a center frequency of a resonance curve of the body coil, and calculating a magnet target frequency based on the determined center frequency. A magnet is ramped to the magnet target frequency.

Abstract: A method of operating a magnetic resonance imaging (MRI) apparatus includes exciting a body coil of the MRI apparatus to emit a radio-frequency signal, determining a center frequency of a resonance curve of the body coil, and calculating a magnet target frequency based on the determined center frequency. A magnet is ramped to the magnet target frequency.

Abstract: A method of operating a magnetic resonance imaging (MRI) apparatus includes exciting a body coil of the MRI apparatus to emit a radio-frequency signal, determining a center frequency of a resonance curve of the body coil, and calculating a magnet target frequency based on the determined center frequency. A magnet is ramped to the magnet target frequency.

Abstract: A calibration method for calibrating a measuring element for determining an electric current flowing through a basic-field magnet of a magnetic resonance imaging system includes performing a measurement with the measuring element, and performing a frequency measurement in the magnetic field of the basic-field magnet with a frequency measuring unit. The measurement of the measuring element and the frequency measurement are corresponding to the same magnetic field of the basic-field magnet. The calibration method also includes calculating a calibration factor based on a deviation between the measurement with the measuring element and the frequency measurement, and calibrating the measuring element or the electric current in the basic-field magnet based on the calibration factor.

Abstract: A calibration method for calibrating a measuring element for determining an electric current flowing through a basic-field magnet of a magnetic resonance imaging system includes performing a measurement with the measuring element, and performing a frequency measurement in the magnetic field of the basic-field magnet with a frequency measuring unit. The measurement of the measuring element and the frequency measurement are corresponding to the same magnetic field of the basic-field magnet. The calibration method also includes calculating a calibration factor based on a deviation between the measurement with the measuring element and the frequency measurement, and calibrating the measuring element or the electric current in the basic-field magnet based on the calibration factor.

Abstract: A fault-tolerant cryogenically cooled system including an outer vacuum chamber defining a vacuum region in its interior volume; a cryogenic refrigerator; equipment to be cooled, housed within the vacuum region; a free volume delimited within the vacuum region and containing a cryogen; a cold plate exposed to the free volume and thermally linked to the equipment to be cooled; a heat exchanger thermally linked to a coldest stage of the refrigerator and exposed to the free volume; a cryogen buffer vessel delimiting a buffer volume; and a passage linking the buffer volume with the free volume.

Abstract: An arrangement for cryogenic cooling includes a cryogen tank, a cryogenic recondensing refrigerator arranged to cool a heat exchanger that is exposed to the interior of the cryogen tank, and an arrangement for conducting heat from a cooled article to the cryogen tank. A further cryogen tank is provided below the heat exchanger and arranged to receive cryogen liquid recondensed on the heat exchanger.

Abstract: An arrangement for cryogenic cooling comprising a cryogen tank (14), a cryogenic recondensing refrigerator (12) arranged to cool a heat exchanger which is exposed to the interior of the cryogen tank (14) and an arrangement (16; 26) for conducting heat from a cooled article (10) to the cryogen tank. A further cryogen tank (20) is provided below the heat exchanger and arranged to receive cryogen liquid recondensed on the heat exchanger.

Abstract: In a method and apparatus for maintaining operation of ancillary equipment associated with a superconducting magnet carrying a DC current, the DC current is directed through a DC-to-AC converter, and the magnitude of the current flowing through the superconducting magnet is ramped down at a controlled rate, thereby generating a controlled voltage across a controlled impedance, and powering the ancillary equipment by the controlled voltage and an associated current, and the ramping rate is controlled in order to maintain a required controlled voltage.

Abstract: In a method and apparatus for maintaining operation of ancillary equipment associated with a superconducting magnet carrying a DC current, the DC current is directed through a DC-to-AC converter, and the magnitude of the current flowing through the superconducting magnet is ramped down at a controlled rate, thereby generating a controlled voltage across a controlled impedance, and powering the ancillary equipment by the controlled voltage and an associated current, and the ramping rate is controlled in order to maintain a required controlled voltage.