To optimize turn on velocity of the SiC LIMS,we proposed a new structure for the LIMS that incorporates an opti-mized n^(+)layer and a multi-light triggered electrode design for the anode.The chip size is 5.5 mm×...To optimize turn on velocity of the SiC LIMS,we proposed a new structure for the LIMS that incorporates an opti-mized n^(+)layer and a multi-light triggered electrode design for the anode.The chip size is 5.5 mm×5.5 mm in dimension.The experiment results indicate that the saturation laser energy required to trigger the prepared SiC LIMS has been decreased from 1.8 mJ to 40μJ,with the forward blocking voltage of the prepared SiC LIMSs capable of withstanding over 7000 V.The leakage current is about 0.3μA at room temperature,and the output current density achieves 4.25 kA/cm^(2)(with di/dt larger than 20 kA/μs).展开更多
The transient resistance,voltage,and power of a nonlinear GaAs photoconductive semiconductor switch （PCSS） are presented by the finite difference formula to deal with the experiment data, based on the conversation o...The transient resistance,voltage,and power of a nonlinear GaAs photoconductive semiconductor switch （PCSS） are presented by the finite difference formula to deal with the experiment data, based on the conversation of energy in the switch circuit. This method resolves the problem of directly measuring the transient characteristics of PCSS in nonlinear mode. The curve of transient voltage shows that the average electric field of PCSS in the lock-on period is always higher than the Gunn threshold,and increases monotonically. By comparing the transient power curves of the PCSS and the electrical source,it is demonstrated directly that the power shortage leads to the PCSS from the lock-on state into the selfturnoff state,so a controllable turnoff of the PCSS in lock-on by changing the distribution of the circuit power is predicted.展开更多
Synchronization for multiple-pulse at nanosecond range shows a great value on the power multiplication and synchronous electric fieldsapplications. Nanosecond or sub-ns jitter synchronization is essential for the impr...Synchronization for multiple-pulse at nanosecond range shows a great value on the power multiplication and synchronous electric fieldsapplications. Nanosecond or sub-ns jitter synchronization is essential for the improved working efficiency of the large amounts of pulse modulesand accurate requirements for the power coherent combining applications. This paper presents a trigger generator based on a laser diodetriggered GaAs photoconductive semiconductor switch (PCSS) with low jitter and compact size characteristics. It avoids the high currentsthat are harmful to high-gain mode PCSSs. In the trigger circuit, a 200 pF capacitor is charged by a microsecond-scale 18 kV pulse and thendischarged via the high-gain mode GaAs PCSS to trigger the high-power trigatron switch. When triggered by the ~10 ns pulse generated by thePCSS, the DC-charged trigatron can operate in the 20e35 kV range with 10 ns rise time and 1 ns delay-time jitter.展开更多
An experimental study of leakage current is presented in a semi-insulating（SI） Ga As photoconductive semiconductor switch（PCSS） with voltages up to 5.8 kV（average field is 19.3 kV/cm）. The leakage current increa...An experimental study of leakage current is presented in a semi-insulating（SI） Ga As photoconductive semiconductor switch（PCSS） with voltages up to 5.8 kV（average field is 19.3 kV/cm）. The leakage current increases nonlinearly with the bias voltage increasing from 1.2×10^-9 A to 3.6×10^-5A. Furthermore, the dark resistance, which is characterized as a function of electric field, does not monotonically decrease with the field but displays several distinct regimes. By eliminating the field-dependent drift velocity, the free-electron density n is extracted from the current, and then the critical field for each region of n（E） characteristic of PCSS is obtained. It must be the electric field that provides the free electron with sufficient energy to activate the carrier in the trapped state via multiple physical mechanisms, such as impurity ionization, fielddependent EL2 capture, and impact ionization of donor centers EL10 and EL2. The critical fields calculated from the activation energy of these physical processes accord well with the experimental results. Moreover, agreement between the fitting curve and experimental data of J（E）, further confirms that the dark-state characteristics are related to these field-dependent processes. The effects of voltage on SI-Ga As PCSS may give us an insight into its physical mechanism.展开更多
High power switch is one of the most important components in pulsed power technology. The RSD （Reversely Switched Dynistor）, turned on by a thin layer of an electron-hole plasma, is a high power semiconductor switch...High power switch is one of the most important components in pulsed power technology. The RSD （Reversely Switched Dynistor）, turned on by a thin layer of an electron-hole plasma, is a high power semiconductor switch. In this study, the RSD turn-on conditions were investigated by numerical analysis and device simulation as well as the experiments conducted to validate the turn-on conditions. A design of a triggering high-voltage RSD is presented based on a saturable transformer.展开更多
Photoconductive semiconductor switch(PCSS)can be applied in pulsed high power systems and microwave techniques.However,reducing the damage and increasing the lifetime of silicon carbide(SiC)PCSS are still faced severe...Photoconductive semiconductor switch(PCSS)can be applied in pulsed high power systems and microwave techniques.However,reducing the damage and increasing the lifetime of silicon carbide(SiC)PCSS are still faced severe challenges.In this study,PCSSs with various structures were prepared on 4-inch diameter,500μm thick high-purity semi-insulating 4H-SiC substrates and their on-state resistance and damage mechanisms were investigated.It was found that the PCSS of an Au/TiW/Ni electrode system annealed at 950℃had a minimum on-state resistance of 6.0Ωat 1 kV bias voltage with a 532 nm and 170 mJ pulsed laser by backside illumination single trigger.The backside illumination single trigger could reduce on-state resistance and alleviate the damage of PCSS compared to the frontside trigger when the diameter of the laser spot was larger than the channel length of PCSS.For the 200 s trigger test by a 10 Hz laser,the black branch-like ablation on Au/TiW/Ni PCSS was mainly caused by thermal stress owing to hot carriers.Replacing metal Ni with boron gallium co-doped zinc oxide(BGZO)thin films annealed at 400℃,black branch-like ablation was alleviated while concentric arc damage was obvious at the anode.The major causes of concentric arc are both pulsed laser diffraction and thermal effect.展开更多
With its unique features, photoconductive semiconductor switch (PCSS) is generally recognized today as a promising power electronic device. However, a major limitation of PCSS is its surprisingly low voltage threshold...With its unique features, photoconductive semiconductor switch (PCSS) is generally recognized today as a promising power electronic device. However, a major limitation of PCSS is its surprisingly low voltage threshold of surface flashover (SF). In this paper, an experimental study of surface flashover of a back-triggered PCSS is presented. The PCSSs with electrode gap of 18 mm are fabricated from liquid encapsulated czochralski (LEC) semi-insulating gallium arsenide (SI-GaAs), and they are either un-coated, or partly coated, or en- tirely coated PCSSs with high-strength transparent insulation. The SF fields of the PCSSs are measured and discussed. According to the experimental results, the high-dielectric-strength coating is efficient in both reducing the gas desorption from semiconductor and increasing the SF field: a well-designed PCSS can resist a voltage up to 20 kV under the repetition frequency of 30 Hz. The physical mechanism of the PCSS SF is analyzed, and the conclusion is made that having a channel structure, the SF is the breakdown of the contaminated dielectric layer at the semiconductor-ambient dielectric interface. The non-uniform distribution of the surface field and the gas desorption due to thermal effects of semiconductor surface currents are key factors causing the SF field reduction.展开更多
Pulsed power technology has an important trend in the world,which has high power,long pulse,high operating frequency and miniaturization.Thus all-solid-state pulsed power technologies based on semiconductor devices ha...Pulsed power technology has an important trend in the world,which has high power,long pulse,high operating frequency and miniaturization.Thus all-solid-state pulsed power technologies based on semiconductor devices have drawn more attention and widely used.This article introduces several kinds of semiconductor switches,such as SCR,IGBT,and SOS.The charging system based on SCR,the Marx generator,and pulsed transformer topology using IGBTs,and the system using SOS are described in detail.Some experimental results are also given.The use of semiconductor switches technology in solid state Marx generate can solve the disappointments such as short life time, low operating frequency,low reliability of conventional pulsed power equipments and has extensive perspective.展开更多
In traditional hybrid DC circuit breakers(HCBs)schemes,complex equipment is usually required to ensure current commutation from mechanical to semiconductor switches,which cause not only additional construction costs a...In traditional hybrid DC circuit breakers(HCBs)schemes,complex equipment is usually required to ensure current commutation from mechanical to semiconductor switches,which cause not only additional construction costs and volume but also additional losses and maintenance work.Different from this condition,a low-loss and compact HCB scheme that does not use separate current commutation equipment is proposed in this study.By rationally using the charge and discharge of the snubber capacitor,the self-commutated semiconductor switch(SCS)module can integrate both the current commutation and shutdown functions,thereby greatly reducing cost and volume.The working process is discussed and analyzed in detail,and then a 10-kA prototype is developed and tested,which verifies the feasibility and effectiveness of the proposed scheme.Index Terms-HVDC circuit breakers,hybrid DC circuit breakers(HCBs),self-commutated semiconductor switch(SCS).展开更多
Experiments with the limited space-charge accumulation（LSA） mode of oscillation in a large gap semiinsulating （SI） GaAs photoconductive semiconductor switch（PCSS） are discussed.It has been observed that growth a...Experiments with the limited space-charge accumulation（LSA） mode of oscillation in a large gap semiinsulating （SI） GaAs photoconductive semiconductor switch（PCSS） are discussed.It has been observed that growth and drift of a photo-activated charge domain（PACD） are quenched only when the bias voltage is more than twice the threshold voltage.The original negative resistance characteristics are directly utilized in the LSA mode;during LSA operation the spatial average of the electric field varies over a large portion of the negative differential mobility region of the velocity-electric field characteristic.The work efficiency of an SI GaAs PCSS is remarkably enhanced by electric field excursions into the positive resistance region when the total electric field is only below the threshold part of the time.The LSA mode can only operate in the certain conditions that satisfy the quenching of the accumulation layer and the smaller initial domain voltage.展开更多
Al-doped ZnO thin film （AZO） is used as a subcontact layer in 6H-SiC photoconductive semiconductor switches （PCSSs） to reduce the on-state resistance and optimize the device structure. Our photoconductive test sho...Al-doped ZnO thin film （AZO） is used as a subcontact layer in 6H-SiC photoconductive semiconductor switches （PCSSs） to reduce the on-state resistance and optimize the device structure. Our photoconductive test shows that the onstate resistance of lateral PCSS with an n＋-AZO subcontact layer is 14.7% lower than that of PCSS without an n＋-AZO subcontact layer. This occurs because a heavy-doped AZO thin film can improve Ohmic contact properties, reduce contact resistance, and alleviate Joule heating. Combined with the high transparance characteristic at 532 nm of AZO film, vertical structural PCSS devices are designed and their structural superiority is discussed. This paper provides a feasible route for fabricating high performance SiC PCSS by using conductive and transparent ZnO-based materials.展开更多
Breakdown characteristics of a gap breakdown load was investigated in this paper, and a reversely switched dynistor （RSD） discharge circuit was designed based on the load. Based on the characteristics of the load, t...Breakdown characteristics of a gap breakdown load was investigated in this paper, and a reversely switched dynistor （RSD） discharge circuit was designed based on the load. Based on the characteristics of the load, the RSD discharge circuit was improved and optimized. The volume of the magnetic switch was reduced. To protect the thyristor and RSD, a diode was anti- parallely connected with the thyristor, which reduced the time requirement when a power voltage was applied to RSD. Experimental results show the circuit designed in this paper can switch a high voltage and high current smoothly, and allows the power voltage to change in a wider range.展开更多
When the capacitor cell is discharged in the short-circuit mode, the current pulse amplitude and duration are maximal. Therefore, this mode is the most severe for discharge switches of capacitive energy storage. The c...When the capacitor cell is discharged in the short-circuit mode, the current pulse amplitude and duration are maximal. Therefore, this mode is the most severe for discharge switches of capacitive energy storage. The characteristics of the transient process of the discharge capacitive energy storage and the current loads acting in the facility discharge circuit have been defined for this mode. The test bench for definition of the LTT(Light Triggered Thyristors) loading capacity is described. The limiting characteristics have been experimentally obtained for LTT, at which there emerges the thermo-generation peak.The process of OFF-ON switching of LTTs has been investigated, the necessity is shown to use the speedup R-C circuits to ensure fast and stable transition of LTT into the conducting state. The design of the switch unit for the capacitive energy storage comprising LTTs and crowbar diodes is described, and the transient processes of current switching in crowbar diodes are considered. The tests carried out during switching of pul se current up to 100 kA at a voltage of 6 kV have confirmed the workability of the switch unit.展开更多
Photostructural changes and electrical switching are the well-known features of amorphous chalcogenides, also known as glassy semiconductors. Although the both phenomena were intensively studied experimentally and hav...Photostructural changes and electrical switching are the well-known features of amorphous chalcogenides, also known as glassy semiconductors. Although the both phenomena were intensively studied experimentally and have a wide practical application, their nature is debated up to now. I propose a new approach that considers glass as a self-organizing system owing to characteristic instability of chemical bonding in the form of bond wave. The bond wave model is shown to be suitable for explanation of the observed effects in thin films under the action of light or electrical field, a result that opens a new way for understanding and managing the processes in glassy semiconductors.展开更多
This paper overviews the benefits,challenges,research trends and potential solutions on the design and application of gallium nitride(GaN) technology in hard-switching power electronic converters from the device level...This paper overviews the benefits,challenges,research trends and potential solutions on the design and application of gallium nitride(GaN) technology in hard-switching power electronic converters from the device level up to converter level.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
基金supported by Rector’s fund of China Academy of Engineering Physics(Grant No.YZJJZQ2022002)the National Natural Science Foundation of China(Grant No.61504127).
文摘To optimize turn on velocity of the SiC LIMS,we proposed a new structure for the LIMS that incorporates an opti-mized n^(+)layer and a multi-light triggered electrode design for the anode.The chip size is 5.5 mm×5.5 mm in dimension.The experiment results indicate that the saturation laser energy required to trigger the prepared SiC LIMS has been decreased from 1.8 mJ to 40μJ,with the forward blocking voltage of the prepared SiC LIMSs capable of withstanding over 7000 V.The leakage current is about 0.3μA at room temperature,and the output current density achieves 4.25 kA/cm^(2)(with di/dt larger than 20 kA/μs).
文摘The transient resistance,voltage,and power of a nonlinear GaAs photoconductive semiconductor switch （PCSS） are presented by the finite difference formula to deal with the experiment data, based on the conversation of energy in the switch circuit. This method resolves the problem of directly measuring the transient characteristics of PCSS in nonlinear mode. The curve of transient voltage shows that the average electric field of PCSS in the lock-on period is always higher than the Gunn threshold,and increases monotonically. By comparing the transient power curves of the PCSS and the electrical source,it is demonstrated directly that the power shortage leads to the PCSS from the lock-on state into the selfturnoff state,so a controllable turnoff of the PCSS in lock-on by changing the distribution of the circuit power is predicted.
基金This work was supported by the National Science Foundation of China under grant No.51477177.
文摘Synchronization for multiple-pulse at nanosecond range shows a great value on the power multiplication and synchronous electric fieldsapplications. Nanosecond or sub-ns jitter synchronization is essential for the improved working efficiency of the large amounts of pulse modulesand accurate requirements for the power coherent combining applications. This paper presents a trigger generator based on a laser diodetriggered GaAs photoconductive semiconductor switch (PCSS) with low jitter and compact size characteristics. It avoids the high currentsthat are harmful to high-gain mode PCSSs. In the trigger circuit, a 200 pF capacitor is charged by a microsecond-scale 18 kV pulse and thendischarged via the high-gain mode GaAs PCSS to trigger the high-power trigatron switch. When triggered by the ~10 ns pulse generated by thePCSS, the DC-charged trigatron can operate in the 20e35 kV range with 10 ns rise time and 1 ns delay-time jitter.
基金supported by the National Natural Science Foundation of China(Grant No.31470822)the Advanced Research Foundation of China(Grant Nos.9140A05030114DZ02068,9140A07030514DZ02101,and 9140A07010715DZ02001)
文摘An experimental study of leakage current is presented in a semi-insulating（SI） Ga As photoconductive semiconductor switch（PCSS） with voltages up to 5.8 kV（average field is 19.3 kV/cm）. The leakage current increases nonlinearly with the bias voltage increasing from 1.2×10^-9 A to 3.6×10^-5A. Furthermore, the dark resistance, which is characterized as a function of electric field, does not monotonically decrease with the field but displays several distinct regimes. By eliminating the field-dependent drift velocity, the free-electron density n is extracted from the current, and then the critical field for each region of n（E） characteristic of PCSS is obtained. It must be the electric field that provides the free electron with sufficient energy to activate the carrier in the trapped state via multiple physical mechanisms, such as impurity ionization, fielddependent EL2 capture, and impact ionization of donor centers EL10 and EL2. The critical fields calculated from the activation energy of these physical processes accord well with the experimental results. Moreover, agreement between the fitting curve and experimental data of J（E）, further confirms that the dark-state characteristics are related to these field-dependent processes. The effects of voltage on SI-Ga As PCSS may give us an insight into its physical mechanism.
基金supported by the National Natural Science Foundation of China (Nos.50277016,50577028)Specialized Research Fund for the Doctoral Program of Higher Education (No.20050487044)
文摘High power switch is one of the most important components in pulsed power technology. The RSD （Reversely Switched Dynistor）, turned on by a thin layer of an electron-hole plasma, is a high power semiconductor switch. In this study, the RSD turn-on conditions were investigated by numerical analysis and device simulation as well as the experiments conducted to validate the turn-on conditions. A design of a triggering high-voltage RSD is presented based on a saturable transformer.
基金National Key R&D Program of China(2021YFA0716304)Shanghai Science and Technology Programs(22511100300,23DZ2201500)。
文摘Photoconductive semiconductor switch(PCSS)can be applied in pulsed high power systems and microwave techniques.However,reducing the damage and increasing the lifetime of silicon carbide(SiC)PCSS are still faced severe challenges.In this study,PCSSs with various structures were prepared on 4-inch diameter,500μm thick high-purity semi-insulating 4H-SiC substrates and their on-state resistance and damage mechanisms were investigated.It was found that the PCSS of an Au/TiW/Ni electrode system annealed at 950℃had a minimum on-state resistance of 6.0Ωat 1 kV bias voltage with a 532 nm and 170 mJ pulsed laser by backside illumination single trigger.The backside illumination single trigger could reduce on-state resistance and alleviate the damage of PCSS compared to the frontside trigger when the diameter of the laser spot was larger than the channel length of PCSS.For the 200 s trigger test by a 10 Hz laser,the black branch-like ablation on Au/TiW/Ni PCSS was mainly caused by thermal stress owing to hot carriers.Replacing metal Ni with boron gallium co-doped zinc oxide(BGZO)thin films annealed at 400℃,black branch-like ablation was alleviated while concentric arc damage was obvious at the anode.The major causes of concentric arc are both pulsed laser diffraction and thermal effect.
基金Project supported by National Natural Science Foundation of China （50837005, 5110 7099）, Foundation of the State Key Laboratory of Electrical Insulation for Power Equip- ment （EIPE09203）.
文摘With its unique features, photoconductive semiconductor switch (PCSS) is generally recognized today as a promising power electronic device. However, a major limitation of PCSS is its surprisingly low voltage threshold of surface flashover (SF). In this paper, an experimental study of surface flashover of a back-triggered PCSS is presented. The PCSSs with electrode gap of 18 mm are fabricated from liquid encapsulated czochralski (LEC) semi-insulating gallium arsenide (SI-GaAs), and they are either un-coated, or partly coated, or en- tirely coated PCSSs with high-strength transparent insulation. The SF fields of the PCSSs are measured and discussed. According to the experimental results, the high-dielectric-strength coating is efficient in both reducing the gas desorption from semiconductor and increasing the SF field: a well-designed PCSS can resist a voltage up to 20 kV under the repetition frequency of 30 Hz. The physical mechanism of the PCSS SF is analyzed, and the conclusion is made that having a channel structure, the SF is the breakdown of the contaminated dielectric layer at the semiconductor-ambient dielectric interface. The non-uniform distribution of the surface field and the gas desorption due to thermal effects of semiconductor surface currents are key factors causing the SF field reduction.
文摘Pulsed power technology has an important trend in the world,which has high power,long pulse,high operating frequency and miniaturization.Thus all-solid-state pulsed power technologies based on semiconductor devices have drawn more attention and widely used.This article introduces several kinds of semiconductor switches,such as SCR,IGBT,and SOS.The charging system based on SCR,the Marx generator,and pulsed transformer topology using IGBTs,and the system using SOS are described in detail.Some experimental results are also given.The use of semiconductor switches technology in solid state Marx generate can solve the disappointments such as short life time, low operating frequency,low reliability of conventional pulsed power equipments and has extensive perspective.
基金supported by the National Natural Science Foundation of China(No.52107004)the China Postdoctoral Science Foundation(No.2020M680484 and No.2021T140201)the Fundamental Research Funds for the Central Universities(No.2021MS003)。
文摘In traditional hybrid DC circuit breakers(HCBs)schemes,complex equipment is usually required to ensure current commutation from mechanical to semiconductor switches,which cause not only additional construction costs and volume but also additional losses and maintenance work.Different from this condition,a low-loss and compact HCB scheme that does not use separate current commutation equipment is proposed in this study.By rationally using the charge and discharge of the snubber capacitor,the self-commutated semiconductor switch(SCS)module can integrate both the current commutation and shutdown functions,thereby greatly reducing cost and volume.The working process is discussed and analyzed in detail,and then a 10-kA prototype is developed and tested,which verifies the feasibility and effectiveness of the proposed scheme.Index Terms-HVDC circuit breakers,hybrid DC circuit breakers(HCBs),self-commutated semiconductor switch(SCS).
基金Project supported by the National Natural Science Foundation of China(Nos.50837005,11204264)the Research Fund for Doctors of Xinjiang Normal University(No.XJNUBS 1220)the Research Fund for the Outstanding Young Teacher of Xinjiang Normal University (No.XJNU1214)
文摘Experiments with the limited space-charge accumulation（LSA） mode of oscillation in a large gap semiinsulating （SI） GaAs photoconductive semiconductor switch（PCSS） are discussed.It has been observed that growth and drift of a photo-activated charge domain（PACD） are quenched only when the bias voltage is more than twice the threshold voltage.The original negative resistance characteristics are directly utilized in the LSA mode;during LSA operation the spatial average of the electric field varies over a large portion of the negative differential mobility region of the velocity-electric field characteristic.The work efficiency of an SI GaAs PCSS is remarkably enhanced by electric field excursions into the positive resistance region when the total electric field is only below the threshold part of the time.The LSA mode can only operate in the certain conditions that satisfy the quenching of the accumulation layer and the smaller initial domain voltage.
基金Project supported by the Innovation Program of the Shanghai Institute of Ceramics(Grant No.Y39ZC1110G)the Innovation Program of the Chinese Academy of Sciences(Grant No.KJCX2-EW-W10)+3 种基金the Industry–Academic Joint Technological Innovations Fund Project of Jiangsu Province,China(Grant No.BY2011119)the Natural Science Foundation of Shanghai(Grant No.14ZR1419000)the Young Scientists Fund of the National Natural Science Foundation of China(Grant No.61404146)the National High-tech R&D Program of China(Grant Nos.2013AA031603 and 2014AA032602)
文摘Al-doped ZnO thin film （AZO） is used as a subcontact layer in 6H-SiC photoconductive semiconductor switches （PCSSs） to reduce the on-state resistance and optimize the device structure. Our photoconductive test shows that the onstate resistance of lateral PCSS with an n＋-AZO subcontact layer is 14.7% lower than that of PCSS without an n＋-AZO subcontact layer. This occurs because a heavy-doped AZO thin film can improve Ohmic contact properties, reduce contact resistance, and alleviate Joule heating. Combined with the high transparance characteristic at 532 nm of AZO film, vertical structural PCSS devices are designed and their structural superiority is discussed. This paper provides a feasible route for fabricating high performance SiC PCSS by using conductive and transparent ZnO-based materials.
基金supported by National Natural Science Foundation of China (No. 50907025)China Postdoctoral Science Foundation (No. 20080440931)
文摘Breakdown characteristics of a gap breakdown load was investigated in this paper, and a reversely switched dynistor （RSD） discharge circuit was designed based on the load. Based on the characteristics of the load, the RSD discharge circuit was improved and optimized. The volume of the magnetic switch was reduced. To protect the thyristor and RSD, a diode was anti- parallely connected with the thyristor, which reduced the time requirement when a power voltage was applied to RSD. Experimental results show the circuit designed in this paper can switch a high voltage and high current smoothly, and allows the power voltage to change in a wider range.
文摘When the capacitor cell is discharged in the short-circuit mode, the current pulse amplitude and duration are maximal. Therefore, this mode is the most severe for discharge switches of capacitive energy storage. The characteristics of the transient process of the discharge capacitive energy storage and the current loads acting in the facility discharge circuit have been defined for this mode. The test bench for definition of the LTT(Light Triggered Thyristors) loading capacity is described. The limiting characteristics have been experimentally obtained for LTT, at which there emerges the thermo-generation peak.The process of OFF-ON switching of LTTs has been investigated, the necessity is shown to use the speedup R-C circuits to ensure fast and stable transition of LTT into the conducting state. The design of the switch unit for the capacitive energy storage comprising LTTs and crowbar diodes is described, and the transient processes of current switching in crowbar diodes are considered. The tests carried out during switching of pul se current up to 100 kA at a voltage of 6 kV have confirmed the workability of the switch unit.
文摘Photostructural changes and electrical switching are the well-known features of amorphous chalcogenides, also known as glassy semiconductors. Although the both phenomena were intensively studied experimentally and have a wide practical application, their nature is debated up to now. I propose a new approach that considers glass as a self-organizing system owing to characteristic instability of chemical bonding in the form of bond wave. The bond wave model is shown to be suitable for explanation of the observed effects in thin films under the action of light or electrical field, a result that opens a new way for understanding and managing the processes in glassy semiconductors.
基金supported by the Engineering Research Center Program of the National Science Foundation and DOE under NSF Award Number EEC-1041877the Current Industry Partnership Program
文摘This paper overviews the benefits,challenges,research trends and potential solutions on the design and application of gallium nitride(GaN) technology in hard-switching power electronic converters from the device level up to converter level.
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.
