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Simulation of Quench in Pancake-shaped Superconducting Magnet Using a Quasi-three-dimensional Model
Wang, Qiuliang,Yoon, Cheon-Seog,Kim, Kee-Man The Korean Superconductivity Society 2000 Progress in superconductivity Vol.1 No.2
A quench phenomenon is caused by an external disturbance in a superconducting magnet, where the magnet is operating in a cryogenic environment. The heat coupling between the layers and pancakes of the magnet can induce the normal zone propagation with fast speed. In order to analyze quench behavior in a pancake-shaped superconducting magnet, a quasi-three-dimensional model is proposed. A moving mesh finite volume method is employed in solving the heat conduction equation. The quench process of the superconducting magnet is studied under the various operating conditions and cooling conditions.
Development of Testing Device for Critical Current Measurements for HTS/LTS
Qiuliang Wang,Yinming Dai,Baozhi Zhao,Shousen Song,Zhiqiang Cao,Shunzhong Chen,Quan Zhang,Housheng Wang,Junsheng Cheng,Yuanzhong Lei,Bai Ye,Xian Li,Jianhua Liu,Shangwu Zhao,Hongjie Zhang,Xinning Hu,Ch IEEE 2009 IEEE transactions on applied superconductivity Vol.19 No.3
<P>For the goal of superconducting magnet applications in the advanced testing device for high temperature superconducting (HTS) wire and sample coils, a wide bore conduction-cooled superconducting magnet with available warm bore of phi 186 mm and center field of 5 T for the background magnetic field applications was designed and fabricated and tested. A sample cryostat with two GM cryocoolers is inserted in the background magnet. The system allows measurements to be performed in a repeatable and reliable fashion. The detailed design, fabrication and thermal analysis are presented in the paper.</P>
Numerical Model for Thermal Hydraulic Analysis in Cable-in-Conduit-Conductors
Wang, Qiuliang,Kim, Kee-Man,Yoon, Cheon-Seog The Korean Society of Mechanical Engineers 2000 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.14 No.9
The issue of quench is related to safety operation of large-scale superconducting magnet system fabricated by cable-in-conduit conductor. A numerical method is presented to simulate the thermal hydraulic quench characteristics in the superconducting Tokamak magnet system, One-dimensional fluid dynamic equations for supercritical helium and the equation of heat conduction for the conduit are used to describe the thermal hydraulic characteristics in the cable-in-conduit conductor. The high heat transfer approximation between supercritical helium and superconducting strands is taken into account due to strong heating induced flow of supercritical helium. The fully implicit time integration of upwind scheme for finite volume method is utilized to discretize the equations on the staggered mesh. The scheme of a new adaptive mesh is proposed for the moving boundary problem and the time term is discretized by the-implicit scheme. It remarkably reduces the CPU time by local linearization of coefficient and the compressible storage of the large sparse matrix of discretized equations. The discretized equations are solved by the IMSL. The numerical implement is discussed in detail. The validation of this method is demonstrated by comparison of the numerical results with those of the SARUMAN and the QUENCHER and experimental measurements.
Design of Superconducting Magnet for Background Magnetic Field
Qiuliang Wang,Yinming Dai,Baozhi Zhao,Souseng Song,Shunzhong Chen,Luguang Yan,Keeman Kim IEEE 2008 IEEE transactions on applied superconductivity Vol.18 No.2
<P>For the advanced testing of High Temperature Superconducting (HTS) wire/tape and sample coils, a wide bore conduction-cooled superconducting magnet with the available warm bore of 0186 mm and a center field of 5~6 T for background magnetic field applications was designed and fabricated. The magnet is composed of four coaxial coils. All the coils were connected in series and can be powered with a single power supply. The maximum magnetic field is 5.5 T. In order to support the high stress in superconducting magnet a detailed finite element (FE) analysis with electro-plastic model has been performed. A compact cryostat with a two-stage GM cryocooler was designed and manufactured for the magnet. The detailed design of magnet system is described in this paper.</P>
Qiuliang Wang,Guoxin Xu,Yinming Dai,Baozhi Zhao,Luguang Yan,Keeman Kim IEEE 2009 IEEE transactions on applied superconductivity Vol.19 No.3
<P>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.</P>
A 30 kJ Bi2223 High Temperature Superconducting Magnet for SMES with Solid-Nitrogen Protection
Qiuliang Wang,Yinming Dai,Souseng Song,Huaming Wen,Ye Bai,Luguang Yan,Keeman Kim IEEE 2008 IEEE transactions on applied superconductivity Vol.18 No.2
<P>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.</P>
Development of a Digital Quench Detection and Dumping Circuit With Constant Voltage System for SMES
Shunzhong Chen,Qiuliang Wang,Yinming Dai,Yuanzhong Lei,Keeman Kim IEEE 2010 IEEE transactions on applied superconductivity Vol.20 No.3
<P>A digital quench detection and protection system has been developed for a micro-sized superconducting magnetic energy storage system (SMES). The digital quench detection system based on a high-performance NI-6224 digital acquisition card accepts a standard set of input signal such as magnet induced voltage, current, pressure of cryostat. It also provides improved signal processing for sensitive and exact quench detection and data logging function. Once the superconducting magnet quenches, the quench detection system activates immediately the protection circuit. Some novel protection circuits are developed to dump the electromagnetic energy stored in the magnet; these greatly enhance the dump efficiency by maintaining the magnet terminal voltage constant during the dumping energy process. This paper detailedly describes the system and presents results.</P>
Development of Strain Measurement in Superconducting Magnet Through Fiber Bragg Grating
Hongjie Zhang,Fanping Deng,Qiuliang Wang,Luguang Yan,Yingming Dai,Keeman Kim IEEE 2008 IEEE transactions on applied superconductivity Vol.18 No.2
<P>Temperature and strain responses of fiber Bragg grating sensors were measured in cryogenic environment. With temperature from room temperature down to 77 K or 4.2 K, the temperature response was found to be relatively linear above 100 K, and the temperature sensitivity decreases with the decrease of temperature, and to approximately zero for temperature less than 50 K. Technologies were developed to eliminate the multi-peaks in strain experiment, so the strain response was measured at 77 K, and was found to be linear at constant temperatures.</P>