Field of the Invention
The present invention concerns low-temperature superconducting technology, in particular a thermal radiation shield for a superconducting magnet, and a superconducting magnet and a magnetic resonance imaging apparatus with such a shield.
Description of the Prior Art
In superconductive magnetic resonance imaging (MRI), selected dipoles in a subject are excited and a magnetic resonance signal emitted by the dipoles is received, so as to generate an image based on the magnetic resonance signal. To encourage excitation of the selected dipoles in the subject, a strong uniform magnetic field is needed. The strong uniform magnetic field can be generated by a superconducting magnet coil operating at low temperature. To thermally isolate the superconducting magnet coil, and protect it from interference from heat in forms such as conduction, convection and radiation in the surrounding environment, the superconducting magnet must be thermally isolated using a thermal radiation shield.
A thermal radiation shield comprises a cylindrical inner tube and a cylindrical outer tube arranged around the periphery of the inner tube, as well as an annular end cap which is disposed between the inner tube and the outer tube and is connected in a fixed manner to both the inner tube and the outer tube. To obtain better heat conduction characteristics, the material chosen for the outer tube is often soft, such as aluminum metal, but the annular end cap then needs to be able to provide the necessary support for the outer tube, in order to prevent the outer tube from being deformed under the action of external forces, such as electromagnetic forces.
In the prior art, a decorative border structure is generally provided at an outer edge of the annular end cap, for fitting to the outer tube, so as to provide the necessary support for the outer tube at the same time as the decorative border structure is fitted to the outer tube. However, shaping of the decorative border structure requires the use of punching, spinning and similar processes, and when shaping is complete, it is still necessary to perform additional machining processes such as milling, thus the processing is complex, and the time costs and process costs of the thermal radiation shield are high.