Theory, Design, Technics And Realization Of Long Pulse High Magnetic Field System Driven By Battery

High magnetic field, as a kind of extreme condition, has become a more and more important tool in modern scientific research. High magnetic field is divided into continuous high magnetic field and pulse high magnetic field. The continuous high magnetic field can last for a long time, but the investment and operation cost is very high, also the field intensity is low. The pulse high magnetic field has high field intensity, but the field can only last for a very short time. It can’t satisfy some of the scientific research, besides, the signal acquisition is relatively difficult in short pulse magnetic field. Long pulse high magnetic field combined the advantages of field intensity and lasting time, can improve the use of high magnetic in scientific research.The pulsed power system used in WHMFC consists of parallel capacitor banks and pulsed generator. As a low energy density storage system, the capacitor banks are normally used for generating short pulsed magnetic field. Although the pulsed generator has a high energy density and good control characteristics, it always suffers from the complex control method and high harmonic interference output. Compared with the two power system referred before, the battery bank has the merits of high energy storage, DC current output and no harmonic interference. Hence, a battery bank is adopted as the power of the pulsed magnetic field.Firstly, the pulsed discharge characteristics of the battery bank are studied in theory and experiment. The pulsed discharge characteristics of the lead-acid battery are measured, including the current, voltage and the resistance. The experiment results certificates the design well.The pulsed magnet is the key of the pulsed magnetic field facility. Based on the pulsed discharge parameters of the battery, the author has done a study about long pulsed magnets and the optimization of the power supply. For analyzing the most critical problem of temperature rise in the long pulsed magnets, the relationship between the magnet temperature rise with the magnet shape and volume, revealed the contradictory relationship between the volume increases to reduce the temperature rise and the capacity of power supply. And Combined with the battery-powered circuit, the author conducted a pulse magnet electric, magnetic, thermal multi-physics coupling analysis, analyzed the influences of temperature rise resulting from the parameter change on the discharge process and the magnetic-field waveform. Proposed to improve the long-pulsed magnetic field waveform by controlling the magnet temperature rise, the final magnet optimization process is to seek the optimum configuration relationship between the power supply capacity and the magnetic field strength and pulse width.According to the design theory of the pulsed magnetic field, a40T long pulsed magnet system is designed. Due to the large volume of the pulsed magnet, it is difficult in structure design and manufacturing. This paper presents an optimized helix magnet coil, which has inner distribution reinforcement instead of cooling channel and a slit in the ends of the coil in order to avoid the electromagnetic force induced by the eddy current.The manufacture process of the magnet is very important because it often decides whether the pulse magnet can work properly and the highest magnetic field intensity it can reach. Any small defect in the process may cause damage or shorten the life of a pulse magnet. This paper has proposed solutions for problems existing in the processing, insulation, reinforcement and assembly process of the Helix inner coil. And the electrode welding and the winding process of the outer copper coil are also described in detail.The author has completed the construction of the long pulse high magnetic field device at Wuhan National High Magnetic Field Center. The composition of this apparatus system and other critical components are desired in this paper, and the final test results of the power and magnet are also given.Based on the long pulse high magnetic field system, the author has also discussed the method for building high stability long pulse high magnetic field, which can be realized by the combination of magnet and power or imposing some auxiliary means. Comparison on the feasibility and stability level between several methods has been made in the paper.Finally, the author summarizes these studies and discussed on further improvement and development of the magnets and power.