Luguang Yan

Development of wide-bore conduction-cooled superconducting magnet system for material processing applications

The application of high magnetic field to material processing, so called electromagnetic processing of material (EPM) has been recognized as cutting edge technology, especially in the field of advanced material processing. It is the most effective methods to control thermal, mass and energy transfer during material solidification. A wide-bore conduction-cooled superconducting magnet with operating current of 116 A was designed, fabricated and tested for the material processing devices. The superconducting magnet has the effective warm hole of 18 cm, the maximum center field of 6 T and homogeneity of 5% in diameter of 5 cm. After the Nb/sub 3/Sn coil insert installed, the magnet can provide the maximum center field of 10 T with effective warm bore of 10 cm. A second-stage GM cryocooler with the second-stage cooling power of 1 W is used to cool the superconducting magnet from room temperature to 4.2 K. In this paper, the design, fabrication, test, stress analysis and quench protection characteristics are presented.

Development and Application of the Maglev Transportation System

The development of the Maglev train is a very important achievement in passenger transportation for the 20th century. Based on the recent information this paper describes the development of different Maglev systems, the application of Maglev for passenger transportation, and the experience of promoting the Maglev transportation in China.

Design of Open High Magnetic Field MRI Superconducting Magnet With Continuous Current and Genetic Algorithm Method

An optimization design method of short-length actively shielded and open structure superconducting MRI magnets is suggested in the paper. Firstly, the section of the solenoid coil is simplified as a current loop with zero section to solve a linear programming problem. The position coordinates in the radius and axial, and current for the loop can be calculated by the linear programming method. Then, the cross-section of the coil is optimized with a genetic algorithm to get appropriate section size. The method of linear programming, especially combining with genetic algorithm, reduces optimizing variables, which makes the design of a magnet feasible. Based on the method, a full open MRI superconducting magnet is designed with maximum radii of 0.8 m and 1.2 m. In the paper, the detailed optimization technologies are presented.

High Temperature Superconducting YBCO Insert for 25 T Full Superconducting Magnet

A 25 T superconducting magnet with a 10 T YBCO high temperature superconducting (HTS) insert and a 15 T low temperature superconducting (LTS) (Nb3Sn and NbTi) outsert is fabricated. To design the superconducting magnet system, an optimal design software which combined the advantages of global optimization and local optimization has been proposed to study the number and type of coils to affect the final optimal results, and some important characteristics, for example, coil hoop stress and operating margin and quench characteristics are studied. The high temperature superconductor YBCO inserts with the inner diameter of 41 mm, the height of 115 mm, and outer diameter of 124 mm have been designed and fabricated with the operating temperature at 4.2 K. The outserts of NbTi and Nb3Sn with the inner diameter, outer diameter and height of 180.22, 443, and 400.5 mm, respectively, have been fabricated and tested. It reaches to the operating magnetic field at 15 T. The combined HTS and LTS coils can generate a central field of 25 T at 4.2 K. In this paper, the 25 T superconducting magnet with LTS and HTS coils are reported.

High Magnetic Field Superconducting Magnet System Up to 25 T for ExCES

The ultra-high-field superconducting magnets have been widely applied in scientific instruments for condensed matter physics. A superconducting magnet with the center field of 25 T in a warm bore-size of 32 mm in diameter has been designed for the Extreme Condition Experimental Science Facility (ExCES). The superconducting magnet consists of NbTi, Nb3Sn superconducting coils and YBCO high-temperature superconducting (HTS) insert operated at the 4.2 K. In order to prove the technical feasibility to achieve the target of 25 T, high-temperature superconductor YBCO and Bi2223 inserts have been designed, fabricated and tested in the operating temperature of 4.2 K. Inner diameter, outer diameter, and height for the YBCO insert are 40 mm, 68.9 mm, and 253 mm, respectively. The larger Bi2223 insert has the inner diameter, outer diameter, and height of 120 mm, 212 mm, and 268.8 mm, respectively. Tests at liquid helium temperature show that the YBCO and Bi2223 inserts can generate the center field of 5 T and 5.05 T, respectively. The assembly of the Bi2223 and YBCO insert coils can generate a center magnetic field of 7.6 T when tested at the liquid helium temperature. In this paper, the design, fabrication, and test of the HTS insert and the 25 T magnet are reported.

A 30 kJ Bi2223 High Temperature Superconducting Magnet for SMES with Solid-Nitrogen Protection

A conduction-cooled high temperature superconducting (HTS) magnet system through a solid nitrogen protection with energy storage of 30 kJ was developed. The HTS magnet system is used to investigate fast discharging performances with a constant output voltage. The superconducting magnet consists of 14 double pancakes wound with Bi2223 tape with the length of 200 m. The magnet has an outer diameter of 212 mm and a clear bore of 108 mm. Cryostat for the HTS magnet system is designed and the coil is cooled with a GM cryocooler together with the solid nitrogen protection technology. The superconducting magnet is fabricated and tested. The operating current is about 155 A with raping rate of 5 A/s. It can generate a central magnetic field of 4.31 T at a temperature lower than 20 K. In this paper, the magnet design, coil fabrication and cryogenic system are presented. Experimental research of the superconducting magnet as a constant voltage power supply was carried out.

Tests on a 6 T Conduction-Cooled Superconducting Magnet

A 6 T conduction-cooled superconducting magnet was designed, fabricated and tested. The magnet is composed of two coaxial NbTi solenoid coils with identical axial length. Clear bore of the magnet is phi 226 mm. The magnet is installed in a vacuum cryostat with a phi 100 mm room temperature bore. The cryostat is designed in a support frame to be rotatable in a horizontal or vertical direction. A two-stage 4 K Gifford-McMahon (GM) cryocooler is used to cool down the superconducting magnet from room temperature to 4 K. The cooling power of the 4 K cold head is 1 W. A pair of Bi-2223 high temperature superconducting current leads was employed to reduce heat leakage into 4 K cold mass. Total cold mass of the superconducting magnet is about 115 kg. It takes 82 hours to cool down the magnet from 300 K to 4 K directly through the cryocooler. The superconducting magnet reached the designed central magnetic field of 6 T in the warm bore when a 115 A energizing current is applied. The superconducting magnet was stably operating more than 275 hours continuously in full field. Further, a Nb3Sn coil insert to be installed, the magnet can provide the maximum center field of 10 T with effective warm bore of phi 100 mm. In this paper, the detailed design, fabrication and test are presented

High Magnetic Field Superconducting Magnet for 400 MHz Nuclear Magnetic Resonance Spectrometer

A superconducting magnet with the center field of 9.4 T is designed and fabricated for 400 MHz Nuclear Magnetic Resonance. Superconducting coil with NbTi/Cu superconducting wire is employed and cooled by re-condensed liquid helium and the magnet system with the clear-bore of 54 mm. The pulsed tube refrigerator with separated valve is employed to cool the magnet system. The superconducting magnet has an active shield with high pure copper shield to protect during quench of the shielding coil. The paper reports the electromagnetic design, and fabrication is detailed.

Quench Protection Design of a 1.5 T Superconducting MRI Magnet

A 1.5 T superconducting MRI magnet has been developed in our laboratory. A passive quench protection system is employed to avoid the damage through the quench event. The coils are subdivided into several groups and a heater network is implemented accordingly. With the control volume method, the numerical model of the quench time is introduced. Different design schemes of the heater strip are compared. The simulation results of currents and voltages are illustrated and the temperature rise of the coils and the heaters are discussed.

A new flywheel energy storage system using hybrid superconducting magnetic bearings

The high temperature superconductor (HTS) YBaCuO coupled with permanent magnets has been applied to construct the superconducting magnetic bearings (SMB) which can be utilized in some engineering fields such as the flywheel energy storage system (FESS). However, there are many problems needed to be resolved, such as low stiffness and damping, the uncertainty of working displacement, flux creep and flux flow. In this paper, a new FESS using hybrid SMB system which consists of SMB, active magnetic bearings (AMB), and permanent magnetic bearings (PMB) is presented. In this design, the authors constructed an experimental device for the FESS with hybrid SMB. An axial PMB is joined to provide a levitation force so as to suspend a heavier flywheel; in addition, two AMB are added in radial degrees to improve the stiffness by two orders of magnitude from 10/sup 4/ N/m to 10/sup 6/ N/m and the damping of FESS.