Recently, the single metal wire （SW） has become attractive for its potential applications in the terahertz and higher frequency range. However, as the most simple and typical surface plasmon polariton （SPP） transm...Recently, the single metal wire （SW） has become attractive for its potential applications in the terahertz and higher frequency range. However, as the most simple and typical surface plasmon polariton （SPP） transmission line, its study seems far from enough. Many important transmission behaviours have not been explained satisfactorily from the viewpoint of physics. In this paper, making use of the modified Drude model （MDM） based on the Sommerfeld theory, the transmission behaviours of SPPs along SW are systemically investigated theoretically. Some important physical phenomena such as the mode transformation, the lifetime of the radiative mode and the resonance frequency are revealed, and their mechanisms are explored. The results obtained in the paper will facilitate a general understanding of the features and the physical essence of the SPP transmission, not only for SW itself but also for other SPP transmission lines.展开更多
In this paper, a computational model is constructed to investigate the phenomenon of the initial plasma formation and current transfer in the single-wire electrical explosion in a vacuum. The process of the single-wir...In this paper, a computational model is constructed to investigate the phenomenon of the initial plasma formation and current transfer in the single-wire electrical explosion in a vacuum. The process of the single-wire electrical explosion is divided into four stages. Stage Ⅰ： the wire is in solid state. Stage Ⅱ： the melting stage. Stage Ⅲ： the wire melts completely and the initial plasma forms. Stage IV： the core and corona expand separately. The thermodynamic calculation is applied before the wire melts completely in stages Ⅰ and Ⅱ. In stage Ⅲ, a one-dimensional magnetohydrodynamics model comes into play until the instant when the voltage collapse occurs. The temperature, density, and velocity, which are derived from the magnetohydrodynamics calculation, are averaged over the distribution area. The averaged parameters are taken as the initial conditions for stage Ⅳ in which a simplified magnetohydrodynamics model is applied. A wide-range semi-empirical equation of state, which is established based on the Thomas-Fermi-Kirzhnits model, is constructed to describe the phase transition from solid state to plasma state. The initial plasma formation and the phenomenon of current transfer in the electrical explosion of aluminum wire are investigated using the computational model. Experiments of electrical explosion of aluminum wires are carried out to verify this model. Simulation results are also compared with experimental results of the electrical explosion of copper wire.展开更多
By using transmission electron microscopy, the microstructures of drawn industrial single crystal copper wires produced by Ohno Continuous Casting(OCC) process were analyzed. The results show that the typical microstr...By using transmission electron microscopy, the microstructures of drawn industrial single crystal copper wires produced by Ohno Continuous Casting(OCC) process were analyzed. The results show that the typical microstructures in the wires mainly include extended planar dislocation boundaries, a small fraction of twins and some dislocation cells sharing boundaries parallel to drawn direction. Besides the typical microstructures, 9R structure configurations were observed in the wires. The formation of 9R polytypes may be caused by the coupled emission of Shockley dislocations from a boundary.展开更多
The experimental system for electrically exploding single metal wire has been designed and manufactured. Expansion of the dense plasma column formed from an electrically exploding Cu wire of diameter 30 μm has been s...The experimental system for electrically exploding single metal wire has been designed and manufactured. Expansion of the dense plasma column formed from an electrically exploding Cu wire of diameter 30 μm has been studied with a high-speed photographer to obtain the time-dependent radius (R-t) curve. The experimental results demonstrate that the mean expansion rate of the dense plasma column is 1.94 μm/ns, 2.6 μm/ns and 3.75 μm/ns according to the peak pulse current 4.5 kA, 7 kA and 9.5 kA respectively. The results can be beneficial to giving a profound understanding of the early stage of wire-array Z-pinch physics and to improvement on their design.展开更多
To identify flow patterns in horizontal gas-liquid flows,a single-wire capacitance probe was used for voltage output for the first time.Regardless of the measurement accuracy of water layer height,the statistic parame...To identify flow patterns in horizontal gas-liquid flows,a single-wire capacitance probe was used for voltage output for the first time.Regardless of the measurement accuracy of water layer height,the statistic parameters of the voltage-time traces were compared within the same sampling time of 5s under different flow patterns,including maximum,minimum,range,and average.The results show that most of flow pattens were accurately identified except for some transition lines.展开更多
The initial stage of wire array Z-pinch,i.e.the energy deposition stage in single wire electrical explosion,plays a very important role in the performance of the whole Z-pinch process.In this paper,this stage was mode...The initial stage of wire array Z-pinch,i.e.the energy deposition stage in single wire electrical explosion,plays a very important role in the performance of the whole Z-pinch process.In this paper,this stage was modeled and simulated.Based on a mathematic model coupled with external circuit,the influence of wire dimension on the waveforms of current and voltage and the voltage-peak time in the energy deposition stage was studied.The calculated specific power indicates that time of the energy deposition extends with wire length quadratically.For normal wire dimension of wire array Z-pinch,the energy deposition time decreases slowly with the decreasing wire diameter,until approaches a minimum depended on the wire length.展开更多
It is important for the safety of transmission system to accurately calculate single-phase earth fault current distribution.Features of double sided elimination method were illustrated.Quantitative calculation of sing...It is important for the safety of transmission system to accurately calculate single-phase earth fault current distribution.Features of double sided elimination method were illustrated.Quantitative calculation of single-phase earth fault current distribution and case verification were accomplished by using the loop method.Influences of some factors,such as single-phase earth fault location and ground resistance of poles,on short-circuit current distribution were discussed.Results show that:1) results of the loop method conform to those of double sided elimination method;2) the fault location hardly influences macro-distribution of short-circuit current.However,current near fault location is evidently influenced;and 3) the short-circuit current distribution is not so sensitive to the ground resistance of poles.展开更多
基金Project supported by the Specialized Research Fund for Doctoral Program of Higher Education of China (Grant No.20100185110022)the National Basic Research Program of China (Grant No. 2007CB310401)the Fundamental Research Funds for the Central Universities of Ministry of Education of China (Grant No. ZYGX2011J037)
文摘Recently, the single metal wire （SW） has become attractive for its potential applications in the terahertz and higher frequency range. However, as the most simple and typical surface plasmon polariton （SPP） transmission line, its study seems far from enough. Many important transmission behaviours have not been explained satisfactorily from the viewpoint of physics. In this paper, making use of the modified Drude model （MDM） based on the Sommerfeld theory, the transmission behaviours of SPPs along SW are systemically investigated theoretically. Some important physical phenomena such as the mode transformation, the lifetime of the radiative mode and the resonance frequency are revealed, and their mechanisms are explored. The results obtained in the paper will facilitate a general understanding of the features and the physical essence of the SPP transmission, not only for SW itself but also for other SPP transmission lines.
基金Project supported by the National Science Foundation of China(Grant Nos.51322706,51237006,and 51325705)the Program for New Century Excellent Talents in University,China(Grant No.NCET-11-0428)the Fundamental Research Funds for the Central Universities,China
文摘In this paper, a computational model is constructed to investigate the phenomenon of the initial plasma formation and current transfer in the single-wire electrical explosion in a vacuum. The process of the single-wire electrical explosion is divided into four stages. Stage Ⅰ： the wire is in solid state. Stage Ⅱ： the melting stage. Stage Ⅲ： the wire melts completely and the initial plasma forms. Stage IV： the core and corona expand separately. The thermodynamic calculation is applied before the wire melts completely in stages Ⅰ and Ⅱ. In stage Ⅲ, a one-dimensional magnetohydrodynamics model comes into play until the instant when the voltage collapse occurs. The temperature, density, and velocity, which are derived from the magnetohydrodynamics calculation, are averaged over the distribution area. The averaged parameters are taken as the initial conditions for stage Ⅳ in which a simplified magnetohydrodynamics model is applied. A wide-range semi-empirical equation of state, which is established based on the Thomas-Fermi-Kirzhnits model, is constructed to describe the phase transition from solid state to plasma state. The initial plasma formation and the phenomenon of current transfer in the electrical explosion of aluminum wire are investigated using the computational model. Experiments of electrical explosion of aluminum wires are carried out to verify this model. Simulation results are also compared with experimental results of the electrical explosion of copper wire.
基金Project(50771076) supported by the National Natural Science Foundation of ChinaProject(07JK274) supported by the Education Department of Shaanxi Province, China
文摘By using transmission electron microscopy, the microstructures of drawn industrial single crystal copper wires produced by Ohno Continuous Casting(OCC) process were analyzed. The results show that the typical microstructures in the wires mainly include extended planar dislocation boundaries, a small fraction of twins and some dislocation cells sharing boundaries parallel to drawn direction. Besides the typical microstructures, 9R structure configurations were observed in the wires. The formation of 9R polytypes may be caused by the coupled emission of Shockley dislocations from a boundary.
基金The project supported by Pre-research Foundation of Chinese Acadeny of Engineering Physics(No.20010103)
文摘The experimental system for electrically exploding single metal wire has been designed and manufactured. Expansion of the dense plasma column formed from an electrically exploding Cu wire of diameter 30 μm has been studied with a high-speed photographer to obtain the time-dependent radius (R-t) curve. The experimental results demonstrate that the mean expansion rate of the dense plasma column is 1.94 μm/ns, 2.6 μm/ns and 3.75 μm/ns according to the peak pulse current 4.5 kA, 7 kA and 9.5 kA respectively. The results can be beneficial to giving a profound understanding of the early stage of wire-array Z-pinch physics and to improvement on their design.
基金Supported by Postdoctoral Foundation of P R China(Grant No:20080440619)
文摘To identify flow patterns in horizontal gas-liquid flows,a single-wire capacitance probe was used for voltage output for the first time.Regardless of the measurement accuracy of water layer height,the statistic parameters of the voltage-time traces were compared within the same sampling time of 5s under different flow patterns,including maximum,minimum,range,and average.The results show that most of flow pattens were accurately identified except for some transition lines.
基金Project supported by National Natural Science Foundation of China （51237006 51322706）.
文摘The initial stage of wire array Z-pinch,i.e.the energy deposition stage in single wire electrical explosion,plays a very important role in the performance of the whole Z-pinch process.In this paper,this stage was modeled and simulated.Based on a mathematic model coupled with external circuit,the influence of wire dimension on the waveforms of current and voltage and the voltage-peak time in the energy deposition stage was studied.The calculated specific power indicates that time of the energy deposition extends with wire length quadratically.For normal wire dimension of wire array Z-pinch,the energy deposition time decreases slowly with the decreasing wire diameter,until approaches a minimum depended on the wire length.
文摘It is important for the safety of transmission system to accurately calculate single-phase earth fault current distribution.Features of double sided elimination method were illustrated.Quantitative calculation of single-phase earth fault current distribution and case verification were accomplished by using the loop method.Influences of some factors,such as single-phase earth fault location and ground resistance of poles,on short-circuit current distribution were discussed.Results show that:1) results of the loop method conform to those of double sided elimination method;2) the fault location hardly influences macro-distribution of short-circuit current.However,current near fault location is evidently influenced;and 3) the short-circuit current distribution is not so sensitive to the ground resistance of poles.
