A crowbar impulse current circuit for testing the switch-type surge protective device （SPD） is presented. The crowbar circuit consists of a computer control circuit, a trigger voltage pulse generator, a main dischar...A crowbar impulse current circuit for testing the switch-type surge protective device （SPD） is presented. The crowbar circuit consists of a computer control circuit, a trigger voltage pulse generator, a main discharging switch, and a crowbar pseudospark switch. The active trigger technology was studied in the crowbar impulse current circuit. The circuit monitors the main discharging current and generates a trigger signal at a proper time for the crowbar pseudospark switch operation. The trigger characteristics of the main discharge switch and the crowbar pseu- dospark switch were investigated. By monitoring the preset applied capacitor voltage, the gap distance of the main discharging switch could be adjusted to ensure a discharging delay time less than 2 μs. Equipped with a surface ttashover trigger device made of high relative perimittivity dielectric material BaTiO3 （εr = 3460）, the discharge delay time of the crowbar pseudospark switch is less than 85 ns, and the minimum operating voltage is less than 1% of its self-breakdown voltage. With a storage capacitor of 9 μF , an inductor of 18 μH and a crowbar pseudospark switch, a load of 30 mΩ and an applied capacitor voltage of 40 kV, an impulse current waveform of maximum 25 kA was generated with a rise time and time to half peak value of 17.2 μs and 336μs respectively.展开更多
A trigger device and a triggered pseudospark switch （TPSS） were designed based on surface flashover technology, in order to meet the requirements from present pulse power technology and pulse current test technology...A trigger device and a triggered pseudospark switch （TPSS） were designed based on surface flashover technology, in order to meet the requirements from present pulse power technology and pulse current test technology such as a long lifetime, reliability in a wide voltage range, a short delay time, as well as small delay jitters. The trigger devices were made from different dielectric materials, with their permittivities from tens to thousands. The trigger characteristics of TPSS were investigated. The results indicate that the high-dielectric trigger device shows better performance and higher emitted charge of the electron emission within all adjusted parameters including the gas pressure and applied voltage. For the dielectric material with relative permittivity εr of 3460, when the gas pressure is 7 Pa, the hold-off voltage of TPSS is 28 kV, the minimum trigger switch voltage drops to 128 V, the minimum discharging delay time and delay jitter are less than 35ns and 6ns, respectively, and the reliable operation can be reached within a very large range of charging voltage, between 0.46% and 99% of its self-breakdown voltage.展开更多
Accurate and reliable triggering is one of the most important issues with high power pseudospark switch, because it not only has an impact on the design of discharge chamber of switch, but also has an influence on the...Accurate and reliable triggering is one of the most important issues with high power pseudospark switch, because it not only has an impact on the design of discharge chamber of switch, but also has an influence on the dynamic range of operation voltage, repetition frequencies and lifetime of switch. The unique feature of pseudospark switch is its hollow cathode geometry. The hollow cathode effect produced by the hollow cathode provides the protection of the switch for the triggering unit from erosion by high discharge plasma. In this paper, a zinc oxide (ZnO) surface flashover triggering is presented. This trigger unit possesses an excellent time delay (80 ns - 360 ns) and jitter (20 ns - 50 ns) at the switch voltage of 30 kV - 2 kV. The emitted plasma electron density is high enough to trigger switch reliably down to switch voltage of 440 V.展开更多
This is a report of the emittance and brightness measurement of an electron beam produced in a pseudospark discharge device driven by a pulse line accelerator. A ten_gap pseudospark device was operated at 200 kV, in a...This is a report of the emittance and brightness measurement of an electron beam produced in a pseudospark discharge device driven by a pulse line accelerator. A ten_gap pseudospark device was operated at 200 kV, in a nitrogen gas fill pressure of 15 Pa. The typical value of emittance was measured to be 47 mm·mrad about 5 cm downstream of the anode plane. The dependence of the beam current, HWHM emittance, the normalized emittance, and the normalized brightness on the axial distance from the anode were obtained. The highest brightness is about 2.7×10 12 A/(mrad)\+2 near the anode, and is still higher than 10 10 A/(mrad)\+2, 160 mm downstream of the anode. Such a high quality electron beam can be used for Raman free electron laser, X ray laser producing, and high power microwave.展开更多
Pseudospark discharge is a kind of gas discharge Which occurs at high voltages(10kV—【1MV) and low pressures (1—100Pa) in a special axial symmetric geometry—the so-called pseudospark chamber (PSC). The device with ...Pseudospark discharge is a kind of gas discharge Which occurs at high voltages(10kV—【1MV) and low pressures (1—100Pa) in a special axial symmetric geometry—the so-called pseudospark chamber (PSC). The device with an insulator disc being in-serted between a hollow cathode (HC) and a plane anode both with a common centralchannel is called the single-gap PSC. We call stacks of alternative insulator and展开更多
The design details and performance characterization results of a newly developed plasma focus based compact and portable system(0.5 m×0.5 m×1.2 m,weighing≈100 kg)that produces an average neutron yield of^2&...The design details and performance characterization results of a newly developed plasma focus based compact and portable system(0.5 m×0.5 m×1.2 m,weighing≈100 kg)that produces an average neutron yield of^2×10^8 neutrons/shot(of fast D-D neutrons with typical energy^2.45 Me V)at^1.8 k J energy discharge are reported.From the detailed analysis of the experimental characterization and simulation results of this system,it has been conclusively revealed that specifically in plasma focus devices with larger static inductance:(i)pinch current is a reliable and more valid neutron yield scaling parameter than peak current,(ii)the ratio of pinch/peak current improves as static inductance of the system reduces,(iii)the benign role of the higher static/pinch inductance ratio enables the supply of inductively stored energy in densely pinched plasma with a larger time constant and it is well depicted by the extended dip observed in the discharge current trace,(iv)there is the need to redefine existing index values of the pinch(Ipinch^4.7)and peak(Ipeak^3.9)currents in neutron yield scaling equations to higher values.展开更多
To satisfy the demands for compact,inexpensive terahertz(THz)sources with power of hundreds of watts,a radial sheet beam THz source which does not require an external magnetic field and is driven by a radial pseudospa...To satisfy the demands for compact,inexpensive terahertz(THz)sources with power of hundreds of watts,a radial sheet beam THz source which does not require an external magnetic field and is driven by a radial pseudospark discharge plasma electron gun(PSDP-EGUN)is proposed.Radial design has been used in pseudospark switches,but in this paper the design of a PSDP-EGUN to drive a radial THz source is presented for the first time.Being different from the latest reported axial quasi-rectangular sheet beam THz sources driven by an axial PSDP-EGUN,a new desig n consisti ng of a circular plate-shaped sheet beam that is directly gen erated by the radial PSDP-EGUN is reported.As compared to an axial system,the radial configuration may result in a larger beam current and a larger beam-wave interaction area together with a higher potential of THz output power.Theoretical analysis and pailicle-in-cell simulation have been employed in the design of the radial sheet beam THz source.Output powers in the kilowatt range have been observed in the simulation of this 0.22 THz source.Preliminary experimental results of the radial PSDP-EGUN are also presented.展开更多
Pseudospark-sourced electron beam is a promising candidate for driving vacuum electronic devices to generate millimeter wave and terahertz wave radiation as it has a very high combined beam current density. However, t...Pseudospark-sourced electron beam is a promising candidate for driving vacuum electronic devices to generate millimeter wave and terahertz wave radiation as it has a very high combined beam current density. However, the inherent velocity spread of the beam, which is difficult to measure in experiment, has a great influence on the operating frequency and efficiency of the vacuum electronic device. In this paper, the velocity distribution characteristics of the electron beam produced by a single-gap hollow cathode electron gun are numerically studied and a three-dimensional kinetic plasma simulation model of a single-gap hollow cathode electron gun is built by using particle in cell and Monte Carlo collision methods in Vorpal. Based on the simulation model, the time-dependent evolution of the plasma formation inside the hollow cathode and electron beam generation process are observed. It is demonstrated that the pseudospark-sourced electron beam has a relatively large velocity spread. The time-dependent velocity distribution of the beam is analyzed, and the dependence of the beam velocity distribution under various operating conditions such as anode–cathode potential difference, gas pressure, and cathode aperture size are also studied.展开更多
文摘A crowbar impulse current circuit for testing the switch-type surge protective device （SPD） is presented. The crowbar circuit consists of a computer control circuit, a trigger voltage pulse generator, a main discharging switch, and a crowbar pseudospark switch. The active trigger technology was studied in the crowbar impulse current circuit. The circuit monitors the main discharging current and generates a trigger signal at a proper time for the crowbar pseudospark switch operation. The trigger characteristics of the main discharge switch and the crowbar pseu- dospark switch were investigated. By monitoring the preset applied capacitor voltage, the gap distance of the main discharging switch could be adjusted to ensure a discharging delay time less than 2 μs. Equipped with a surface ttashover trigger device made of high relative perimittivity dielectric material BaTiO3 （εr = 3460）, the discharge delay time of the crowbar pseudospark switch is less than 85 ns, and the minimum operating voltage is less than 1% of its self-breakdown voltage. With a storage capacitor of 9 μF , an inductor of 18 μH and a crowbar pseudospark switch, a load of 30 mΩ and an applied capacitor voltage of 40 kV, an impulse current waveform of maximum 25 kA was generated with a rise time and time to half peak value of 17.2 μs and 336μs respectively.
文摘A trigger device and a triggered pseudospark switch （TPSS） were designed based on surface flashover technology, in order to meet the requirements from present pulse power technology and pulse current test technology such as a long lifetime, reliability in a wide voltage range, a short delay time, as well as small delay jitters. The trigger devices were made from different dielectric materials, with their permittivities from tens to thousands. The trigger characteristics of TPSS were investigated. The results indicate that the high-dielectric trigger device shows better performance and higher emitted charge of the electron emission within all adjusted parameters including the gas pressure and applied voltage. For the dielectric material with relative permittivity εr of 3460, when the gas pressure is 7 Pa, the hold-off voltage of TPSS is 28 kV, the minimum trigger switch voltage drops to 128 V, the minimum discharging delay time and delay jitter are less than 35ns and 6ns, respectively, and the reliable operation can be reached within a very large range of charging voltage, between 0.46% and 99% of its self-breakdown voltage.
基金The project supported by the National Nature Science Foundation of China(No.10035020)
文摘Accurate and reliable triggering is one of the most important issues with high power pseudospark switch, because it not only has an impact on the design of discharge chamber of switch, but also has an influence on the dynamic range of operation voltage, repetition frequencies and lifetime of switch. The unique feature of pseudospark switch is its hollow cathode geometry. The hollow cathode effect produced by the hollow cathode provides the protection of the switch for the triggering unit from erosion by high discharge plasma. In this paper, a zinc oxide (ZnO) surface flashover triggering is presented. This trigger unit possesses an excellent time delay (80 ns - 360 ns) and jitter (20 ns - 50 ns) at the switch voltage of 30 kV - 2 kV. The emitted plasma electron density is high enough to trigger switch reliably down to switch voltage of 440 V.
文摘This is a report of the emittance and brightness measurement of an electron beam produced in a pseudospark discharge device driven by a pulse line accelerator. A ten_gap pseudospark device was operated at 200 kV, in a nitrogen gas fill pressure of 15 Pa. The typical value of emittance was measured to be 47 mm·mrad about 5 cm downstream of the anode plane. The dependence of the beam current, HWHM emittance, the normalized emittance, and the normalized brightness on the axial distance from the anode were obtained. The highest brightness is about 2.7×10 12 A/(mrad)\+2 near the anode, and is still higher than 10 10 A/(mrad)\+2, 160 mm downstream of the anode. Such a high quality electron beam can be used for Raman free electron laser, X ray laser producing, and high power microwave.
基金Project supported by the National Natural Science Foundation of China.
文摘Pseudospark discharge is a kind of gas discharge Which occurs at high voltages(10kV—【1MV) and low pressures (1—100Pa) in a special axial symmetric geometry—the so-called pseudospark chamber (PSC). The device with an insulator disc being in-serted between a hollow cathode (HC) and a plane anode both with a common centralchannel is called the single-gap PSC. We call stacks of alternative insulator and
文摘The design details and performance characterization results of a newly developed plasma focus based compact and portable system(0.5 m×0.5 m×1.2 m,weighing≈100 kg)that produces an average neutron yield of^2×10^8 neutrons/shot(of fast D-D neutrons with typical energy^2.45 Me V)at^1.8 k J energy discharge are reported.From the detailed analysis of the experimental characterization and simulation results of this system,it has been conclusively revealed that specifically in plasma focus devices with larger static inductance:(i)pinch current is a reliable and more valid neutron yield scaling parameter than peak current,(ii)the ratio of pinch/peak current improves as static inductance of the system reduces,(iii)the benign role of the higher static/pinch inductance ratio enables the supply of inductively stored energy in densely pinched plasma with a larger time constant and it is well depicted by the extended dip observed in the discharge current trace,(iv)there is the need to redefine existing index values of the pinch(Ipinch^4.7)and peak(Ipeak^3.9)currents in neutron yield scaling equations to higher values.
文摘To satisfy the demands for compact,inexpensive terahertz(THz)sources with power of hundreds of watts,a radial sheet beam THz source which does not require an external magnetic field and is driven by a radial pseudospark discharge plasma electron gun(PSDP-EGUN)is proposed.Radial design has been used in pseudospark switches,but in this paper the design of a PSDP-EGUN to drive a radial THz source is presented for the first time.Being different from the latest reported axial quasi-rectangular sheet beam THz sources driven by an axial PSDP-EGUN,a new desig n consisti ng of a circular plate-shaped sheet beam that is directly gen erated by the radial PSDP-EGUN is reported.As compared to an axial system,the radial configuration may result in a larger beam current and a larger beam-wave interaction area together with a higher potential of THz output power.Theoretical analysis and pailicle-in-cell simulation have been employed in the design of the radial sheet beam THz source.Output powers in the kilowatt range have been observed in the simulation of this 0.22 THz source.Preliminary experimental results of the radial PSDP-EGUN are also presented.
基金Project supported by the Sichuan Science and Technology Program, China (Grant No. 2019YJ0188)the National Natural Science Foundation of China (Grant Nos. 61671116 and 11905026).
文摘Pseudospark-sourced electron beam is a promising candidate for driving vacuum electronic devices to generate millimeter wave and terahertz wave radiation as it has a very high combined beam current density. However, the inherent velocity spread of the beam, which is difficult to measure in experiment, has a great influence on the operating frequency and efficiency of the vacuum electronic device. In this paper, the velocity distribution characteristics of the electron beam produced by a single-gap hollow cathode electron gun are numerically studied and a three-dimensional kinetic plasma simulation model of a single-gap hollow cathode electron gun is built by using particle in cell and Monte Carlo collision methods in Vorpal. Based on the simulation model, the time-dependent evolution of the plasma formation inside the hollow cathode and electron beam generation process are observed. It is demonstrated that the pseudospark-sourced electron beam has a relatively large velocity spread. The time-dependent velocity distribution of the beam is analyzed, and the dependence of the beam velocity distribution under various operating conditions such as anode–cathode potential difference, gas pressure, and cathode aperture size are also studied.
