Chinese Academy of Sciences

Qiuliang Wang

Xinning Hu

Yinming Dai

Hui Wang

Luguang Yan

Chunyan Cui

Jianyi Xu

Housheng Wang

Baozhi Zhao

Jianhua Wang

Shousen Song

Wei Lin

Yaohui Wang

Lankai Li

Lijian Ding

Yuanzhong Lei

Chunzhong Wang

Jinyan Lu

Zhipeng Ni

Shunzhong Chen

An intelligent liquid helium-free whole-body magnetic resonance imaging superconducting magnet system, comprising: a vacuum container, provided with a main magnetic field superconducting coil in a radially inner side position therein, and a shielding superconducting coil in a radially outer side position therein, and a heat pipe gas tank is arranged in a vacant area between the main magnetic field superconducting coil and the shielding superconducting coil; a liquid helium reservoir, communicated with a liquid-gas storage tank, and connected with the main magnetic field superconducting coil or the shielding superconducting coil via a helium self-oscillation heat pipe; a refrigerator, fixed on the vacuum container through a thermal conduction component auto-pluggable component; the first thermal conduction component connected with the refrigerator is in close contact with the thermal radiation screen assembly, and the second thermal conduction component connected with the refrigerator is in close contact with the liquid helium reservoir.

Magnetic resonance imaging superconducting magnet system

The present application provides a method of designing a high shielding gradient coil for a planar superconducting magnetic resonance imaging (MRI) system and a gradient coil thereof, the method determines a shielding area according to an outer profile of a metal conductor around the position of the gradient coil in the planar superconducting MRI system, and performs partitioned shielding of a stray field. The constraint values of stray fields at different partitioned zones of the shielding area are adjusted according to the shielding requirements. The primary coils of both the transverse gradient coil and the longitudinal gradient coil optimized by the design method of the high shielding gradient coil contain a reverse coil, which generates a magnetic field that offsets leakage magnetic field of other coils, thus achieving the purpose of reducing the stray field of the gradient coil.

Method of designing a high shielding gradient coil for a planar superconducting magnetic resonance imaging system and gradient coil thereof

Provided is a gravity gradient measurement apparatus and measuring method, wherein a turntable rotates horizontally around an earth-vertical axis, a vacuum layer is arranged on the turntable defining a first chamber, a first three-axis accelerometer and a second three-axis accelerometer are located in the first chamber, the first three-axis accelerometer and the second three-axis accelerometer are arranged symmetrically on an x axis with respect to an origin of coordinates. Both the first three-axis accelerometer and the second three-axis accelerometer have a distance of R from the origin of coordinates. The first three-axis accelerometer and the second three-axis accelerometer are arranged symmetrically on an z axis with respect to the origin of coordinates, and the first three-axis accelerometer and the second three-axis accelerometer are spaced at a distance of h on the z axis. The measurement module uses measurements of the accelerometers to determine gravity gradients on the coordinate axes.

Gravity gradient measurement method and apparatus

A strong-magnetic focused magnet system with a terahertz source includes a first superconducting main coil and a second superconducting main coil. The second superconducting main coil surrounds the outer surface of the first superconducting main coil, and the second superconducting main coil is coaxial with the first superconducting main coil.

Strong-magnetic-focused magnet system with terahertz source

A device and a method for inhibiting vibration of a superconducting magnetic suspension rotor. The device comprises a rotor cavity housing, lateral coils, a superconducting rotor with a rotor top plane, a copper plate, pole shoes, a z-axial vibration measuring sensor, an x-axial vibration measuring sensor, a y-axial vibration measuring sensor, and a copper ring, the pole shoes having a spherical inner surface and being arranged symmetrically up and down so as to form a rotor cavity; the annular lateral coils being closely adjacent to an outside cylindrical surface of the rotor cavity housing and fixed to the same; the z-axial vibration measuring sensor being fixed to a central region of the copper plate; the x-axial vibration measuring sensor being mounted along an x-coordinate axis and the y-axial vibration measuring sensor mounted on a on the copper ring which is mounted along an equatorial plane of the rotor.

Device and method for inhibiting vibration of superconducting magnetic suspension rotor

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

A low-temperature superconducting device for measuring gravity, includes a low-temperature container, a cryocooler, a rotor chamber, a superconducting rotor, an upper levitation coil, a lower levitation coil, an upper electrode, an intermediate electrode, a lower electrode, a magnetic shielding chamber and a superconducting quantum interference device. By cooling the whole low-temperature superconducting device using a cryocooler, the intermediate electrode disposed in the body of the magnetic shielding chamber will generate an output voltage when the superconducting rotor is displaced due to a change of gravity. Thus, the superconducting quantum interference device can make the superconducting rotor return to the central balance position by adjusting the operating current of the upper levitation coil or the lower levitation coil. A change of gravity can be determined based on the operating current fed back to the upper levitation coil or the lower levitation coil.

Low-temperature superconducting device for measuring gravity

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.

High magnetic field superconducting magnet system with large crossing warm bore

A superconducting magnet system for generating high homogeneity and high magnetic field consists of a main coil, an outer coil, a quench protection circuit, a quench heater and a power supply. The main coil is composed of many concentric solenoid coils which are arranged from inside to outside. The outer coil out of the main coil includes a first back roll coil, a second back roll coil, a first superconducting coil for compensating sixth harmonic component, a second superconducting coil for compensating sixth harmonic component, a shielding ring and a shielding coil from inside to outside. Every loop circuit of the quench protection circuit is composed of a corresponding protection resistor, a diode and coil which is connected in series each other, and each coil has a corresponding quench protection heater. The classification linear diameter difference of the superconducting coils which contact each other in main coil is less than 0.05 mm. The homogeneity of the magnetic field in the 50 mm diameter working space is 0.15 ppm, because the high order harmonic component of the field is compensated by back roll method.

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Beijing, China

Qiuliang Wang