Chinese Academy of Sciences

Luguang Yan

Qiuliang Wang

Xinning Hu

Yinming Dai

Hui Wang

Housheng Wang

Baozhi Zhao

Jianhua Wang

Jianyi Xu

Shousen Song

Wei Lin

Zhipeng Ni

Chunzhong Wang

Lankai Li

Shunzhong Chen

Lijian Ding

Yuanzhong Lei

A superconducting magnet system for head imaging is disclosed which includes a cryocooler, a high-pressure helium container, a self-excitation heat pipe and a superconducting magnet. A second stage coldhead of the cryocooler is connected to the high-pressure helium container for converting the helium gas in the high-pressure helium container into liquid helium. The self-excitation heat pipe forms a closed cooling loop, and liquid helium in the high-pressure helium container flows circularly in the self-excitation heat pipe. The self-excitation heat pipe cools the superconducting magnet, wherein part of the liquid helium in the self-excitation heat pipe is converted into the helium gas due to the heat disturbance generated by the superconducting magnet, and the helium gas interacts with the liquid helium to generate liquid helium vibration.

Superconducting magnet system for head imaging

An open type nuclear magnetic resonance magnet system having an iron ring member. A superconducting coil and a superconducting switch form a closed-loop current circuit to generate a magnetic field. The generated magnetic field gains a magnetic flux circuit and executes magnetic field shielding through upper and lower iron yokes and a lateral iron yoke. The magnet system generates a desired magnetic field in a magnet imaging central area via the superconducting coil. To balance the extremely high electromagnetic force between the superconducting coil and the upper and lower iron yokes, an annular iron ring is mounted in a space defined by an inner perimeter wall of in a cryogenic container. The magnetic field distribution between the superconducting coil and the upper and lower iron yokes is changed via the iron ring, so that the electromagnetic interaction force therebetween is reduced.

Open-type nuclear magnetic resonance magnet system having an iron ring member

A self-shield open magnetic resonance imaging superconducting magnet comprises five pairs of coils: shim coils, first main magnetic coils, second main magnetic coils, third main magnetic coils, and shielding coils. The five pairs of coils are symmetric about the center. The shim coils are arranged closest to the center point; the first main magnetic coils, the second main magnetic coils, the third main magnetic coils, and the shielding coils are arranged in sequence outside. The first main magnetic coils are connected with reverse current. The second and third main magnetic coils are connected with positive current for providing the main magnetic field strength. The shim coils are connected with positive current for compensating the magnetic field in the central region. The shielding coils are connected with reverse current for creating a magnetic field opposite to the main magnetic field for compensating the stray magnetic field in the space.

Self-shield open magnetic resonance imaging superconducting magnet

A superconducting magnet system for nuclear magnetic resonance with a high magnetic field and a high degree of homogeneity of magnetic field is provided. The system comprises a main coil and a magnetic field homogeneity compensating coil having a combination of a forward current and a reverse current, and is composed of 24 superconducting coils formed by winding NbTi/Cu low-temperature superconducting wires. The system can produce a magnetic field of 9.4 T within a room-temperature space of 800 mm and can obtain a degree of non-homogeneity of magnetic field less than 0.1 ppm within a spherical volume of 300 mm. The system is equipped with a superconducting magnet inside, and a low-temperature vessel for liquid helium provides a low-temperature environment of 4K which is required for the normal operation of the superconducting magnet. A ferro-magnetic shielding system enables the system to have a good electromagnetic compatibility.

Superconducting magnet system for nuclear magnetic resonance with high magnetic field and high degree of homogeneity of magnetic field

A process for fabricating an ultra-low-resistance superconducting joint that has high shielding characteristics. The process includes: corroding copper on the outer surface at the end of a NbTi/Cu superconducting wire to form terminal NbTi superconducting filaments; inserting same number of NbTi superconducting filaments into each through hole of the niobium layer of a Nb/NbTi/Cu multilayer composite rod; pressing at the outside of the Nb/NbTi/Cu multilayer composite rod to combine the Nb/NbTi/Cu multilayer composite rod and NbTi superconducting filaments together to form a joint; and inserting the joint into a YBCO tube, and then filling the YBCO tube with molten bismuth-lead-tin-cadmium (BiPbSnCd) alloy solder to form a superconducting joint with high shielding and low resistance characteristics.

Process for fabricating an ultra-low-resistance superconducting joint having high shielding characteristics

A superconducting magnet system for high power microwave source focusing and cyclotron electronic apparatus is provided, wherein, the superconducting magnet comprises an inner superconducting main coil, an outer superconducting main coil, two end compensation coils, a regulating coil and a central regulating coil. These coils are formed by coiling NbSn/Cu superconducting wire. The superconducting magnet can operate off-line through solid nitrogen formed by a cryocooler and high-pressure nitrogen. The superconducting magnet and the superconducting switch constitute a closed loop, thereby achieving magnetic field stability, without outside electromagnetic interference. The superconducting magnet system can provide a magnetic field having special spatial distribution and high stability.

Superconducting magnet system for high power microwave source focusing and cyclotron electronic apparatus

A high magnetic field superconducting magnet system with large crossing warm bore is disclosed, a superconducting coil thereof includes a low temperature superconducting coil and a high temperature superconducting coil. The superconducting coils are connected to a thermal shield and a flange of a low temperature container by a supporting drawbar, thus the superconducting coils as a whole are supported inside the low temperature container. A thermal switch is connected to a primary cold head and a secondary cold head of the cryocooler. The secondary cold head of the cryocooler is connected to a magnet-reinforced supporting flange at the two ends of the low temperature superconducting coil and the high temperature superconducting coil by a cold conduction strip. The superconducting magnet system has a room temperature bore in horizontal direction and a room temperature bore in vertical direction. A thermal shield outside the room temperature bore in horizontal direction is used for preventing thermal radiation by the room temperature bore in horizontal direction to the superconducting coils. A separation supporting frame separates the low temperature superconducting coil and the high temperature superconducting coil into two parts, such that a two-dimensional room temperature space can be included inside the superconducting magnet when the superconducting magnet system is formed as a whole.

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Beijing, China

Luguang Yan