Based on the principle of thermal conduction, three metal alloys （stainless steel, copper-tungsten and graphite） were chosen as the material of the high impulse current discharging switch. Experimental results indic...Based on the principle of thermal conduction, three metal alloys （stainless steel, copper-tungsten and graphite） were chosen as the material of the high impulse current discharging switch. Experimental results indicate that the mass loss and surface erosion morphology of the electrode are related with the electrode material （conductivity σ, melting point Tin, density p and thermal capacity c） and the impulse transferred charge （or energy） per impulse for the same total impulse transferred charge. The experimental results indicate that the mass loss of stainless steel, copper-tungsten and graphite are 380.10 μg/C, 118.10 μg/C and 81.90 μg/C respectively under the condition of a total impulse transferred charge of 525 C and a transferred charge per impulse of 10.5 C. Under the same impulse transferred charge, the mass loss of copper-tungsten（118.10 μg/C） with the transferred charge per impulse at 10.5 C is far larger than the mass loss （38.61μg/C） at a 1.48 C transferred charge per impulse. The electrode erosion mechanism under high energy impulse arcs is analyzed briefly and it is suggested that by selecting high conductive metal or metal alloy as the electrode material of a high energy impulse spark gap switch and setting high erosion resistance material at the top of the electrode, the mass loss of the electrode can be reduced and the life of the switch prolonged.展开更多
The optimal axial position of the trigger-electrode of the field-distortion spark gap is investigated through electric field calculation. The electric fields of the gap are calculated when locating trigger-electrode a...The optimal axial position of the trigger-electrode of the field-distortion spark gap is investigated through electric field calculation. The electric fields of the gap are calculated when locating trigger-electrode at different positions. It is shown that if the distance d between the trigger electrode and the low electric potential electrode is greater than 1.3 mm, the maximum field intensity occurs at the edge of the trigger-electrode, which will facilitate the generation of multi-channel discharge. According to calculated results, the working characteristics of the gap is investigated and it shows that when d=1.4 mm the field distortion gap can be triggered reliably.展开更多
Gas spark gap is widely used in any pulsed power system as the key element which directly determines its repetitive performance and output characteristics. Among many factors of threeelectrode gas spark gap, backgroun...Gas spark gap is widely used in any pulsed power system as the key element which directly determines its repetitive performance and output characteristics. Among many factors of threeelectrode gas spark gap, background pressure is of much importance in determining the gap performance parameters such as the delay and jitter, and relevant studies have been rarely performed. A magneto-hydrodynamic model of the arc in gas spark gap is built and the effects of background pressure on the arc characteristics are discussed in this paper. It is demonstrated that a higher background pressure may result in radial compression of the arc column, a higher arc voltage, and a lower declination rate of arc resistance in the first quarter cycle. Relevant simulation data would be helpful for the optimization of the design of gas spark gap.展开更多
As a new method to protect the spark gap from metal particle contamination, the effect of the metal inserted insulator on the controlling behavior of metal particles was investigated in a quasi-uniform electric field....As a new method to protect the spark gap from metal particle contamination, the effect of the metal inserted insulator on the controlling behavior of metal particles was investigated in a quasi-uniform electric field. Considering that the inserted metal electrodes can decrease the electric field around the insulator and divert the electrostatic force away from the insulator, the method can be used to prevent the particles from moving toward the insulator so as to reduce the possibility of a breakdown. The inserted metal electrodes can reverse the direction of the particles＇ horizontal motion. A study on the insulator shape indicates that the inserted metal electrodes can repulse the particle and improve the particle lifting voltage significantly near the vertical surface of the insulator or ribbed insulator. For the insulator with a tilting surface the inserted metal electrodes have little influence on the particle motion. In addition, the size of the inserted electrodes shows a significant effect on the control of particle motion.展开更多
A simple, low cost, easily maintained, and reliable field distortion spark gap has been developed to operate at a voltage up to 30 kV. The header construction necessary to attach the spark gap switch to a single 12.5 ...A simple, low cost, easily maintained, and reliable field distortion spark gap has been developed to operate at a voltage up to 30 kV. The header construction necessary to attach the spark gap switch to a single 12.5 μF, 40 kV （10 k J） capacitor is described. The main features of the spark gap are its wide range of voltage operation, high current capacity, low inductance and long lifetime. The performance of spark gap has been tested in a plasma focus and results are presented in this report.展开更多
The plasma-jet triggered gas switch （PJTGS） could operate at a low working coefficient with a low jitter. We observed and analyzed the discharge process of the PJTGS at the lowest working coefficient of 47% with the...The plasma-jet triggered gas switch （PJTGS） could operate at a low working coefficient with a low jitter. We observed and analyzed the discharge process of the PJTGS at the lowest working coefficient of 47% with the trigger voltage of 40 kV and the pulse energy of 2 J to evaluate the effect of the plasma jet. The temporal and spatial evolution and the optical emission speclrum of the plasma jet were captured. And the spraying delay time and outlet velocity under different gas pressures were investigated. In addition, the particle in cell with Monte Carlo collision was employed to obtain the particle distribution of the plasma jet varying with time. The results show that, the plasma jet generated by spark discharge is sprayed into a spark gap within tens of nanoseconds, and its outlet velocity could reach 104 m s-1. The plasma jet plays a non-penetrating inducing role in the triggered discharge process of the PJTGS. On the one hand, the plasma jet provides the initial electrons needed by the discharge; on the other hand, a large number of electrons focusing on the head of the plasma jet distort the electric field between the head of the plasma jet and the opposite electrode. Therefore, a fast discharge originated from the plasma jet is induced and quickly bridges two electrodes.展开更多
A multi-gap and multi-channel gas switch with convexo-convex discal planet electrodes was designed and investigated. Eight gaps are formed in series by a trigger electrode, six intermediate electrodes and two high vol...A multi-gap and multi-channel gas switch with convexo-convex discal planet electrodes was designed and investigated. Eight gaps are formed in series by a trigger electrode, six intermediate electrodes and two high voltage electrodes with a uniform gap length of 5 ram. The self breakdown and triggered breakdown performance of the switch are reported. Both the delay time and jitter decrease with the increase in the trigger voltage, switching coefficient and the decrease in the trigger isolating resistor. The delay time of the switch is about 40 ns, and the jitter is less than 2 ns when charged with 4-85 kV and triggered by a voltage pule of -75 kV. The inductance of the switch is about 30 nH.展开更多
The conditions for the formation of spark channels with a bead structure in an inhomogeneous electric field at different polarities of voltage pulses are studied.Voltage pulses with an amplitude of up to 150 kV and a ...The conditions for the formation of spark channels with a bead structure in an inhomogeneous electric field at different polarities of voltage pulses are studied.Voltage pulses with an amplitude of up to 150 kV and a rise time of≈1.5μs were applied across a 45-mm point-to-plane gap.Under these conditions,spark channels consisting of bright and dim regions(bead structure)were observed.It is shown that when current is limited,an increase in the rise time and the gap length does not affect the formation of the bead structure.It was found that an increase in the amplitude of voltage pulses leads to an increase in the length of beads.The appearance of the bead structure is more likely at negative polarity of the pointed electrode.The formation of spark channels was studied with a four-channel ICCD camera.展开更多
文摘Based on the principle of thermal conduction, three metal alloys （stainless steel, copper-tungsten and graphite） were chosen as the material of the high impulse current discharging switch. Experimental results indicate that the mass loss and surface erosion morphology of the electrode are related with the electrode material （conductivity σ, melting point Tin, density p and thermal capacity c） and the impulse transferred charge （or energy） per impulse for the same total impulse transferred charge. The experimental results indicate that the mass loss of stainless steel, copper-tungsten and graphite are 380.10 μg/C, 118.10 μg/C and 81.90 μg/C respectively under the condition of a total impulse transferred charge of 525 C and a transferred charge per impulse of 10.5 C. Under the same impulse transferred charge, the mass loss of copper-tungsten（118.10 μg/C） with the transferred charge per impulse at 10.5 C is far larger than the mass loss （38.61μg/C） at a 1.48 C transferred charge per impulse. The electrode erosion mechanism under high energy impulse arcs is analyzed briefly and it is suggested that by selecting high conductive metal or metal alloy as the electrode material of a high energy impulse spark gap switch and setting high erosion resistance material at the top of the electrode, the mass loss of the electrode can be reduced and the life of the switch prolonged.
基金This work was supported by the National Natural Science Foundation of China No.10035020.
文摘The optimal axial position of the trigger-electrode of the field-distortion spark gap is investigated through electric field calculation. The electric fields of the gap are calculated when locating trigger-electrode at different positions. It is shown that if the distance d between the trigger electrode and the low electric potential electrode is greater than 1.3 mm, the maximum field intensity occurs at the edge of the trigger-electrode, which will facilitate the generation of multi-channel discharge. According to calculated results, the working characteristics of the gap is investigated and it shows that when d=1.4 mm the field distortion gap can be triggered reliably.
基金supported by National Natural Science Foundation of China (No. 51807184)
文摘Gas spark gap is widely used in any pulsed power system as the key element which directly determines its repetitive performance and output characteristics. Among many factors of threeelectrode gas spark gap, background pressure is of much importance in determining the gap performance parameters such as the delay and jitter, and relevant studies have been rarely performed. A magneto-hydrodynamic model of the arc in gas spark gap is built and the effects of background pressure on the arc characteristics are discussed in this paper. It is demonstrated that a higher background pressure may result in radial compression of the arc column, a higher arc voltage, and a lower declination rate of arc resistance in the first quarter cycle. Relevant simulation data would be helpful for the optimization of the design of gas spark gap.
基金National Natural Science Foundation of China(No.50637010)
文摘As a new method to protect the spark gap from metal particle contamination, the effect of the metal inserted insulator on the controlling behavior of metal particles was investigated in a quasi-uniform electric field. Considering that the inserted metal electrodes can decrease the electric field around the insulator and divert the electrostatic force away from the insulator, the method can be used to prevent the particles from moving toward the insulator so as to reduce the possibility of a breakdown. The inserted metal electrodes can reverse the direction of the particles＇ horizontal motion. A study on the insulator shape indicates that the inserted metal electrodes can repulse the particle and improve the particle lifting voltage significantly near the vertical surface of the insulator or ribbed insulator. For the insulator with a tilting surface the inserted metal electrodes have little influence on the particle motion. In addition, the size of the inserted electrodes shows a significant effect on the control of particle motion.
基金supported partially by the Higher Education Commission Project for Plasma Physics of Pakistan
文摘A simple, low cost, easily maintained, and reliable field distortion spark gap has been developed to operate at a voltage up to 30 kV. The header construction necessary to attach the spark gap switch to a single 12.5 μF, 40 kV （10 k J） capacitor is described. The main features of the spark gap are its wide range of voltage operation, high current capacity, low inductance and long lifetime. The performance of spark gap has been tested in a plasma focus and results are presented in this report.
文摘The plasma-jet triggered gas switch （PJTGS） could operate at a low working coefficient with a low jitter. We observed and analyzed the discharge process of the PJTGS at the lowest working coefficient of 47% with the trigger voltage of 40 kV and the pulse energy of 2 J to evaluate the effect of the plasma jet. The temporal and spatial evolution and the optical emission speclrum of the plasma jet were captured. And the spraying delay time and outlet velocity under different gas pressures were investigated. In addition, the particle in cell with Monte Carlo collision was employed to obtain the particle distribution of the plasma jet varying with time. The results show that, the plasma jet generated by spark discharge is sprayed into a spark gap within tens of nanoseconds, and its outlet velocity could reach 104 m s-1. The plasma jet plays a non-penetrating inducing role in the triggered discharge process of the PJTGS. On the one hand, the plasma jet provides the initial electrons needed by the discharge; on the other hand, a large number of electrons focusing on the head of the plasma jet distort the electric field between the head of the plasma jet and the opposite electrode. Therefore, a fast discharge originated from the plasma jet is induced and quickly bridges two electrodes.
基金supported by National Natural Science Foundation of China(Nos.50477019,50637010)the State Key Laboratory of Electrical Insulation and Power Equipment of China(EIPE.09207)
文摘A multi-gap and multi-channel gas switch with convexo-convex discal planet electrodes was designed and investigated. Eight gaps are formed in series by a trigger electrode, six intermediate electrodes and two high voltage electrodes with a uniform gap length of 5 ram. The self breakdown and triggered breakdown performance of the switch are reported. Both the delay time and jitter decrease with the increase in the trigger voltage, switching coefficient and the decrease in the trigger isolating resistor. The delay time of the switch is about 40 ns, and the jitter is less than 2 ns when charged with 4-85 kV and triggered by a voltage pule of -75 kV. The inductance of the switch is about 30 nH.
基金The work is performed in the framework of the State task for HCEI SB RAS,project#13.1.4.
文摘The conditions for the formation of spark channels with a bead structure in an inhomogeneous electric field at different polarities of voltage pulses are studied.Voltage pulses with an amplitude of up to 150 kV and a rise time of≈1.5μs were applied across a 45-mm point-to-plane gap.Under these conditions,spark channels consisting of bright and dim regions(bead structure)were observed.It is shown that when current is limited,an increase in the rise time and the gap length does not affect the formation of the bead structure.It was found that an increase in the amplitude of voltage pulses leads to an increase in the length of beads.The appearance of the bead structure is more likely at negative polarity of the pointed electrode.The formation of spark channels was studied with a four-channel ICCD camera.
