In a magnet system: —a superconducting main field magnet (7) generates a magnetic field in a first sample volume (16), —a superconducting additional field magnet (22) generates another field in a second sample volume (24), —a cryostat (2) has a cooled main coil container (6), an evacuated RT (room temperature) covering (4), and an RT bore (14) which extends through the main and the additional field magnets, and —a cooled additional coil container (21) in a vacuum. The RT covering has a flange connection (17) with an opening (19) through which the RT bore extends, a front end of the additional coil container protrudes through the opening into the RT covering such that the additional field magnet also protrudes through the opening into the RT covering, and a closure structure (20) seals the RT covering between the flange connection and the RT bore.

In a magnet system: —a superconducting main field magnet (7) generates a magnetic field in a first sample volume (16), —a superconducting additional field magnet (22) generates another field in a second sample volume (24), —a cryostat (2) has a cooled main coil container (6), an evacuated RT (room temperature) covering (4), and an RT bore (14) which extends through the main and the additional field magnets, and —a cooled additional coil container (21) in a vacuum. The RT covering has a flange connection (17) with an opening (19) through which the RT bore extends, a front end of the additional coil container protrudes through the opening into the RT covering such that the additional field magnet also protrudes through the opening into the RT covering, and a closure structure (20) seals the RT covering between the flange connection and the RT bore.

A method of correcting a magnetic field of a medical apparatus (300) comprising a magnetic resonance imaging system (302). The MRI system includes a magnet (306) for generating the magnetic field within an imaging zone 318. The magnet generates a magnetic field with a zero crossing (346, 404) outside of the imaging zone. The medical apparatus further comprises a gantry (332) configured for rotating a ferromagnetic component (336, 510) about a rotational axis (333). The method comprises the step of installing (100, 200) a magnetic correcting element (348, 900, 1000) located on a radial path (344, 504) perpendicular to the rotational axis. The magnetic correcting element is positioned on the radial path such that change in the magnetic field within the imaging zone due to the ferromagnetic component is reduced. The method further comprises repeatedly: measuring (102, 202, 1204) the magnetic field within the imaging zone; determining (104, 204, 1206) the change in the magnetic field in the imaging zone; and adjusting (106, 206, 1208) the position of the magnetic correcting element along the radial path if the change in the magnetic field is above a predetermined threshold.

A magnetic moment arrangement calculation method for magnetic field adjustment by combining correction of a component of a low-order mode with correction of a component of a high-order mode among the eigenmodes so as to calculate arrangement of the magnetic moment for approximately correcting the error magnetic field distribution, in which the low-order mode is an eigenmode group from the first of eigenmode numbers assigned to respective eigenmodes in the magnitude order of singular values to an eigenmode number specified by a first threshold value, in which the high-order mode is an eigenmode group with an eigenmode number more than the first threshold value, and in which a correction amount of the component of the high-order mode is smaller than a correction amount of the component of the low-order mode.

A method includes disposing a downhole tool having a magnet assembly into a wellbore. The method includes generating, using the magnet assembly, a magnetic polarization in a volume into a subterranean region about the wellbore. The method also includes emitting an excitation in the magnetic polarization in the volume in the subterranean region. The method includes detecting, by at least one antenna, a nuclear magnetic resonance response to the excitation of the volume in the subterranean region. The method also includes determining a property of the subterranean region based on the nuclear magnetic resonance response.

A method includes disposing a downhole tool having a magnet assembly into a wellbore. The method includes generating, using the magnet assembly, a magnetic polarization in a volume into a subterranean region about the wellbore. The method also includes emitting an excitation in the magnetic polarization in the volume in the subterranean region. The method includes detecting, by at least one antenna, a nuclear magnetic resonance response to the excitation of the volume in the subterranean region. The method also includes determining a property of the subterranean region based on the nuclear magnetic resonance response.

The invention pertains to advances in real-time methods in nuclear magnetic resonance by offering a new dual-frequency dynamic nuclear polarization (DNP) method that uses a microwave beam to polarize the spins of electrons and concomitantly act as a NMR transmitter.

The invention pertains to advances in real-time methods in nuclear magnetic resonance by offering a new dual-frequency dynamic nuclear polarization (DNP) method that uses a microwave beam to polarize the spins of electrons and concomitantly act as a NMR transmitter.

A main magnetic field correction method for a magnetic resonance imaging system includes: obtaining an estimated image of a phantom based on a first imaging sequence, the first imaging sequence having a variable resonant frequency; pre-correcting a main magnetic field based on the estimated image; obtaining a scanned image of the phantom based on the pre-corrected main magnetic field; and determining whether the quality of the scanned image is within an acceptable range, and if not, returning to the step of obtaining the estimated image.

A manufacturing method for a fluxgate chip, comprising: firstly, selecting two high-resistance silicon wafers, electroplating a ferromagnetic core on the surface of one of the two high-resistance silicon wafers, and providing a ferromagnetic core cavity on the surface of the other high-resistance silicon wafer; then, bonding the two high-resistance silicon wafers up and down; next, respectively providing coil grooves, through grooves and electrode windows on the surfaces of opposite sides of the two high-resistance silicon wafers to form a silicon wafer mold; and finally, filling the surface of the silicon wafer mold with alloy. By means of electroplating, post-bonding and final etching, on the one hand, the formed fluxgate chip has both small thickness and sufficient strength, on the other hand, large-scale batch production of the fluxgate chip can be achieved, the working efficiency is improved, and the production cost is reduced.