Magnetic shielding is very important in the design of a high-power dc comparator. This paper addressed the application of magnetic circuit method to calculate the magnetic shielding effectiveness of high-power dc comp...Magnetic shielding is very important in the design of a high-power dc comparator. This paper addressed the application of magnetic circuit method to calculate the magnetic shielding effectiveness of high-power dc comparators when an external radial magnetic field is added. The mathematical relationship between the magnetic shielding effectiveness and the parameters of the magnetic shielding body were obtained. To verify the validity of the calculation method, we developped a procedure to measure the magnetic shielding effectiveness of the magnetic body by measuring the induction voltage of the detection winding instead of the magnetic intensity at a point in the magnetic shielding body, making the manipulation much easier. The result calculated with the magnetic circuit method turns out to be closer to the measured one compared with that calculated with a conventional algorithm proposed by Ren, suggesting that the magnetic circuit method is an applicable tool for estimating the toroidal cavity magnetic shielding effectiveness of a heavy current comparator when a radial magnetic field is added.展开更多
The strength of the power frequency electric intensity and magnetic field of the 500-kV double circuit transmission lines was calculated by using the equivalent charge method and the Ampere's Law, and the environm...The strength of the power frequency electric intensity and magnetic field of the 500-kV double circuit transmission lines was calculated by using the equivalent charge method and the Ampere's Law, and the environmental impact factors of the fields were evaluated. By optimizing the phase sequence, the frequency electric intensity and magnetic field strength can be reduced. Within a distance of 25 m from the center of the transmission line, the power frequency electric intensity and magnetic field strength fall off sharply with the distance increase. Finally, the best phase sequence and the minimum ground clearance of the transmission lines were obtained to meet the requirements of the least impact on envionment.展开更多
The magnetic field of coaxial permanent magnet Halbach circuit is calculated first using the finite element method SUPERFISH and the approximate expression of the magnet circuit is obtained.The forces acting on IREB&#...The magnetic field of coaxial permanent magnet Halbach circuit is calculated first using the finite element method SUPERFISH and the approximate expression of the magnet circuit is obtained.The forces acting on IREB's electron in such magnetic field are analyzed by the use of fluid model and the radial force equation in modified Mathieu function form is drawn then.At last a 2.5-D particle in-cell(PIC)simulation code is used to investigate the physical process of the IREB's propagation.In the PIC simulation,the electron beam current,thickness,magnet field amplitude and the beam's initial incident angle related to the stable propagation are mainly discussed.The conclusion is made that several kilo-amperes intense annular electron beam could propagate stably,meanwhile the focusing form of such magnet geometry provides action mechanism for the interaction between beam electrons and microwave in the ubitron.展开更多
In the past three decades, molecular magnetism has been a rapidly growing interdisciplinary field in chemistry, phys- ics and materials sciences. It covers diverse range of topics including inorganic/organic/hybrid ma...In the past three decades, molecular magnetism has been a rapidly growing interdisciplinary field in chemistry, phys- ics and materials sciences. It covers diverse range of topics including inorganic/organic/hybrid magnetic molecular ma- terials, multifunctional and/or switchable magnetic molecu- lar materials, molecular nanomagnets, nanostructural mo- lecular magnets, molecular spintronics and biomagnetism. Much research on molecular magnetism has been carried out in China both before and after we organized the Interna- tional Conference on Molecule-Based Magnets 2010 （ICMM 2010） in Beijing.展开更多
基金Funded by the Natural Science Foundation of China under the grant number 50277018.
文摘Magnetic shielding is very important in the design of a high-power dc comparator. This paper addressed the application of magnetic circuit method to calculate the magnetic shielding effectiveness of high-power dc comparators when an external radial magnetic field is added. The mathematical relationship between the magnetic shielding effectiveness and the parameters of the magnetic shielding body were obtained. To verify the validity of the calculation method, we developped a procedure to measure the magnetic shielding effectiveness of the magnetic body by measuring the induction voltage of the detection winding instead of the magnetic intensity at a point in the magnetic shielding body, making the manipulation much easier. The result calculated with the magnetic circuit method turns out to be closer to the measured one compared with that calculated with a conventional algorithm proposed by Ren, suggesting that the magnetic circuit method is an applicable tool for estimating the toroidal cavity magnetic shielding effectiveness of a heavy current comparator when a radial magnetic field is added.
文摘The strength of the power frequency electric intensity and magnetic field of the 500-kV double circuit transmission lines was calculated by using the equivalent charge method and the Ampere's Law, and the environmental impact factors of the fields were evaluated. By optimizing the phase sequence, the frequency electric intensity and magnetic field strength can be reduced. Within a distance of 25 m from the center of the transmission line, the power frequency electric intensity and magnetic field strength fall off sharply with the distance increase. Finally, the best phase sequence and the minimum ground clearance of the transmission lines were obtained to meet the requirements of the least impact on envionment.
文摘The magnetic field of coaxial permanent magnet Halbach circuit is calculated first using the finite element method SUPERFISH and the approximate expression of the magnet circuit is obtained.The forces acting on IREB's electron in such magnetic field are analyzed by the use of fluid model and the radial force equation in modified Mathieu function form is drawn then.At last a 2.5-D particle in-cell(PIC)simulation code is used to investigate the physical process of the IREB's propagation.In the PIC simulation,the electron beam current,thickness,magnet field amplitude and the beam's initial incident angle related to the stable propagation are mainly discussed.The conclusion is made that several kilo-amperes intense annular electron beam could propagate stably,meanwhile the focusing form of such magnet geometry provides action mechanism for the interaction between beam electrons and microwave in the ubitron.
文摘In the past three decades, molecular magnetism has been a rapidly growing interdisciplinary field in chemistry, phys- ics and materials sciences. It covers diverse range of topics including inorganic/organic/hybrid magnetic molecular ma- terials, multifunctional and/or switchable magnetic molecu- lar materials, molecular nanomagnets, nanostructural mo- lecular magnets, molecular spintronics and biomagnetism. Much research on molecular magnetism has been carried out in China both before and after we organized the Interna- tional Conference on Molecule-Based Magnets 2010 （ICMM 2010） in Beijing.
