The types of dopants lead to distinctive microstructural evolution behavior and physical properties in materials.In this study,the effect of stoichiometric and non-stoichiometric Mn modification,namely Pb(Mn_(1/3) Nb_...The types of dopants lead to distinctive microstructural evolution behavior and physical properties in materials.In this study,the effect of stoichiometric and non-stoichiometric Mn modification,namely Pb(Mn_(1/3) Nb_(2/3))O_(3)(PMnN)and MnO_(2),on the microstructure and properties of Pb(Yb_(1/2) Nb_(1/2))O_(3)-PbZrO_(3)-PbTiO_(3)(PYN-PZT)piezoelectric ceramics are systematically investigated.It was found that stoichiometric PMnN modification inhibits the grain growth while non-stoichiometric MnO_(2) modification promotes it,and thus the former yields stronger high-power characteristics(higher internal bias field Ei and larger mechanical quality factor Q_(m))than the latter.Specifically,with an equivalent amount of Mn modifica-tion(2 mol%),PMnN and MnO_(2) modification PYN-PZT ceramics exhibit significantly different values for average grain size(1.21μm vs.14.12μm),Ei(8.5 kV/cm vs.5 kV/cm),and Qm(2376 vs.1134).To further evaluate high-power performance,the vibration velocity v of these two modified PYN-PZT under high driving conditions was measured.Under an AC electric field of 3.5 V/mm,the PYN-PZT+6PMnN ceram-ics exhibit a v of up to 0.95 m s^(−1),larger than both MnO2-doped PYN-PZT(0.72 m s^(−1))and unmodified PYN-PZT ceramics(0.1 m s^(−1)),and far outperformance than both PZT-4 and PZT-8 ceramics.Furthermore,to elucidate the origin of the exceptional high-power performance of PMnN-modified PYN-PZT,we per-formed phase-field simulations revealing a pinning effect of the grain boundary on domain wall motion.Consequently,the small grain size(high grain boundary density)in PMnN-modified PYN-PZT exhibits a strong pinning effect,resulting in a large Q_(m) and outstanding high-power performance.展开更多
Lead magnesium niobate-lead titanate(PMN-PT)piezoelectric single crystals are widely utilized due to their outstanding performance,with varying compositions significantly impacting their properties.While application o...Lead magnesium niobate-lead titanate(PMN-PT)piezoelectric single crystals are widely utilized due to their outstanding performance,with varying compositions significantly impacting their properties.While application of PMN-PT in high-power settings is rapidly evolving,material parameters are typically tested under low signal conditions(1 V),and effects of different PT(PbTiO_(3))contents on the performance of PMN-PT single crystals under high-power conditions remain unclear.This study developed a comprehensive high-power testing platform using the constant voltage method to evaluate performance of PMN-PT single crystals with different PT contents under high-power voltage stimulation.Using crystals sized at 10 mm×3 mm×0.5 mm as an example,this research explored changes in material parameters.The results exhibit that while trend of the parameter changes under high-power excitation was consistent across different PT contents,degree of the change varied significantly.For instance,a PMN-PT single crystal with 26%(in mol)PT content exhibited a 25%increase in the piezoelectric coefficient d_(31),a 13%increase in the elastic compliance coefficient s_(11)^(E),a 17%increase in the electromechanical coupling coefficient k_(31),and a 73%decrease in the mechanical quality factor Q_(m) when the power reached 7.90 W.As the PT content increased,the PMN-PT materials became more susceptible to temperature influences,significantly reducing the power tolerance and more readily reaching the depolarization temperatures.This led to loss of piezoelectric performance.Based on these findings,a clearer understanding of impact of PT content on performance of PMN-PT single crystals under high-power applications has been established,providing reliable data to support design of sensors or transducers using PMN-PT as the sensitive element.展开更多
The Jiama porphyry copper deposit in Xizang is one of the proven supergiant copper deposits in the Qinghai-Tibet Plateau at present,with the reserves of geological resources equivalent to nearly 20×10^(6)t.Howeve...The Jiama porphyry copper deposit in Xizang is one of the proven supergiant copper deposits in the Qinghai-Tibet Plateau at present,with the reserves of geological resources equivalent to nearly 20×10^(6)t.However,it features wavy and steep terrain,leading to extremely difficult field operation and heavy interference.This study attempts to determine the effects of the tensor controlled-source audiomagnetotellurics(CSAMT)with high-power orthogonal signal sources(also referred to as the high-power tensor CSAMT)when it is applied to the deep geophysical exploration in plateaus with complex terrain and mining areas with strong interference.The test results show that the high current provided by the highpower tensor CSAMT not only greatly improved the signal-to-noise ratio but also guaranteed that effective signals were received in the case of a long transmitter-receiver distance.Meanwhile,the tensor data better described the anisotropy of deep geologic bodies.In addition,the tests also show that when the transmitting current reaches 60 A,it is still guaranteed that strong enough signals can be received in the case of the transmitter-receiver distance of about 25 km,sounding curves show no near field effect,and effective exploration depth can reach 3 km.The 2D inversion results are roughly consistent with drilling results,indicating that the high-power tensor CSAMT can be used to achieve nearly actual characteristics of underground electrical structures.Therefore,this method has great potential for application in deep geophysical exploration in plateaus and mining areas with complex terrain and strong interference,respectively.This study not only serves as important guidance on the prospecting in the Qinghai-Tibet Plateau but also can be used as positive references for deep mineral exploration in other areas.展开更多
High-power laser technology is widely used in manufacturing processing,medical diagnosis,and treatment,and is one of the important fields of strategic high-tech competition in China at the moment.In the context of ind...High-power laser technology is widely used in manufacturing processing,medical diagnosis,and treatment,and is one of the important fields of strategic high-tech competition in China at the moment.In the context of industrial upgrading,high-power laser technology plays an important role in leading the development of the manufacturing industry and industrial intelligence.Based on this,this paper carries out research on high-power laser technology and industry,summarizes the basic principle and classification of high-power laser technology,analyzes the current status of high-power laser technology industry,points out the opportunities and challenges faced by the industry development,puts forward suggestions to promote the development of high-power laser technology industry,and to provide an effective reference for the application and development of high-power laser technology.展开更多
The growing demand for efficient high-power switching power supplies has spurred interest in advanced topologies.The three-phase VIENNA converter stands out for its high power factor,simplified structure,and robust pe...The growing demand for efficient high-power switching power supplies has spurred interest in advanced topologies.The three-phase VIENNA converter stands out for its high power factor,simplified structure,and robust performance.Current research focuses on its operational principles,control strategies,and behavior under various load conditions.Key considerations include component selection,thermal management,and EMI/EMC optimization.This topology finds applications across renewable energy systems,industrial equipment,telecommunications,and electric vehicle charging infrastructures.Comparative analyses with alternative topologies and cost-benefit evaluations are also addressed.Future developments are expected to emphasize the integration of wide-bandgap devices and advancements in digital control techniques to further enhance efficiency and system performance.展开更多
This research focuses on solving the fault detection and health monitoring of high-power thyristor converter.In terms of the critical role of thyristor converter in nuclear fusion system,a method based on long short-t...This research focuses on solving the fault detection and health monitoring of high-power thyristor converter.In terms of the critical role of thyristor converter in nuclear fusion system,a method based on long short-term memory(LSTM)neural network model is proposed to monitor the operational state of the converter and accurately detect faults as they occur.By sampling and processing a large number of thyristor converter operation data,the LSTM model is trained to identify and detect abnormal state,and the power supply health status is monitored.Compared with traditional methods,LSTM model shows higher accuracy and abnormal state detection ability.The experimental results show that this method can effectively improve the reliability and safety of the thyristor converter,and provide a strong guarantee for the stable operation of the nuclear fusion reactor.展开更多
Classification of plume and spatter images was studied to evaluate the welding stability. A high-speed camera was used to capture the instantaneous images of plume and spatters during high power disk laser welding. Ch...Classification of plume and spatter images was studied to evaluate the welding stability. A high-speed camera was used to capture the instantaneous images of plume and spatters during high power disk laser welding. Characteristic parameters such as the area and number of spatters, the average grayscale of a spatter image, the entropy of a spatter grayscale image, the coordinate ratio of the plume centroid and the welding point, the polar coordinates of the plume centroid were defined and extracted. Karhunen-Loeve transform method was used to change the seven characteristics into three primary characteristics to reduce the dimensions. Also, K-nearest neighbor method was used to classify the plume and spatter images into two categories such as good and poor welding quality. The results show that plume and spatter have a close relationship with the welding stability, and two categories could be recognized effectively using K-nearest neighbor method based on Karhunen-Loeve transform.展开更多
Based on the particle-in-cell technology and the secondary electron emission theory, a three-dimensional simulation method for multipactor is presented in this paper. By combining the finite difference time domain met...Based on the particle-in-cell technology and the secondary electron emission theory, a three-dimensional simulation method for multipactor is presented in this paper. By combining the finite difference time domain method and the panicle tracing method, such an algorithm is self-consistent and accurate since the interaction between electromagnetic fields and particles is properly modeled. In the time domain aspect, the generation of multipactor can be easily visualized, which makes it possible to gain a deeper insight into the physical mechanism of this effect. In addition to the classic secondary electron emission model, the measured practical secondary electron yield is used, which increases the accuracy of the algorithm. In order to validate the method, the impedance transformer and ridge waveguide filter are studied. By analyzing the evolution of the secondaries obtained by our method, multipactor thresholds of these components are estimated, which show good agreement with the experimental results. Furthermore, the most sensitive positions where multipactor occurs are determined from the phase focusing phenomenon, which is very meaningful for multipactor analysis and design.展开更多
To improve the characteristics of a diamond-like carbon （DLC） film, Ti-containing amorphous hydrogenated carbon thin films were deposited on sus304 stainless steel substrates by high-power plasma-sputtering with tit...To improve the characteristics of a diamond-like carbon （DLC） film, Ti-containing amorphous hydrogenated carbon thin films were deposited on sus304 stainless steel substrates by high-power plasma-sputtering with titanium metal as the solid plasma source in a mixed ArC2H2 atmosphere. The films were fabricated to obtain a multilayered structure of Ti/TiC/DLC gradient for improving adhesion and reducing residual stress. The effects of substrate bias and target-substrate distance on the films＇ properties were studied by glow discharge spectroscope, X-ray diffractometer, Raman spectroscope, nanoindenter, and a pin-on-disk tribometer. The results indicate that the films possess superior adhesive strength and toughness.展开更多
A two-dimensional model of the silicon NPN monolithic composite transistor is established for the first time by utilizing the semiconductor device simulator, Sentaurus-TCAD. By analyzing the internal distributions of ...A two-dimensional model of the silicon NPN monolithic composite transistor is established for the first time by utilizing the semiconductor device simulator, Sentaurus-TCAD. By analyzing the internal distributions of electric field, current density, and temperature of the device, a detailed investigation on the damage process and mechanism induced by high-power microwaves （HPM） is performed. The results indicate that the temperature elevation occurs in the negative half-period and the temperature drop process is in the positive half-period under the HPM injection from the output port. The damage point is located near the edge of the base-emitter junction of T2, while with the input injection it exists between the base and the emitter of T2. Comparing these two kinds of injection, the input injection is more likely to damage the device than the output injection. The dependences of the damage energy threshold and the damage power threshold causing the device failure on the pulse-width are obtained, and the formulas obtained have the same form as the experimental equations, which demonstrates that more power is required to destroy the device if the pulse-width is shorter. Furthermore, the simulation result in this paper has a good coincidence with the experimental result.展开更多
Thermal management is one of the key technologies for high-power Light emitting diode(LED)entering into the general illuminating field.Successful thermal management depends on optimal packaging structure and selected ...Thermal management is one of the key technologies for high-power Light emitting diode(LED)entering into the general illuminating field.Successful thermal management depends on optimal packaging structure and selected packaging materials.In this paper,the aluminum is employed as a substrate of LED,3×3 array chips are placed on the substrate,heat dissipation performance is simulated using finite element analysis(FEA)software,analyzed are the influences on the temperature of the chip with different convection coefficient,and optical properties are simulated using optical analysis software.The results show that the packaging structure can not only effectually improve the thermal performance of high-power LED array but also increase the light extraction efficiency.展开更多
To reduce the energy demand and operation cost for circular electron positron collider(CEPC), the high efficiency klystrons are being developed at Institute of High Energy Physics, Chinese Academy of Sciences. A 800-k...To reduce the energy demand and operation cost for circular electron positron collider(CEPC), the high efficiency klystrons are being developed at Institute of High Energy Physics, Chinese Academy of Sciences. A 800-k W continuous wave(CW) klystron operating at frequency of 650-MHz has been designed. The results of beam–wave interaction simulation with several different codes are presented. The efficiency is optimized to be 65% with a second harmonic cavity in three-dimensional(3D) particle-in-cell code CST. The effect of cavity frequency error and mismatch load on efficiency of klystron have been investigated. The design and cold test of reentrant cavities are described, which meet the requirements of RF section design. So far, the manufacturing and high-power test of the first klystron prototype have been completed.When the gun operated at DC voltage of 80 k V and current of 15.4 A, the klystron peak power reached 804 k W with output efficiency of about 65.3% at 40% duty cycle. The 1-d B bandwidth is ±0.8 MHZ. Due to the crack of ceramic window, the CW power achieved about 700 kW. The high-power test results are in good agreement with 3D simulation.展开更多
Microwave pre-treatment is considered as a promising technique for alleviating cutter wear. This paper introduces a high-power microwave-induced fracturing system for hard rock. The test system consists of a high-powe...Microwave pre-treatment is considered as a promising technique for alleviating cutter wear. This paper introduces a high-power microwave-induced fracturing system for hard rock. The test system consists of a high-power microwave subsystem (100 kW), a true triaxial testing machine, a dynamic monitoring subsystem, and an electromagnetic shielding subsystem. It can realize rapid microwave-induced fracturing, intelligent tuning of impedance, dynamic feedback under strong microwave fields, and active control of microwave parameters by addressing the following issues: the instability and insecurity of the system, the discharge breakdown between coaxial lines during high-power microwave output, and a lack of feedback of rock-microwave response. In this study, microwave-induced surface and borehole fracturing tests under true triaxial stress were carried out. Experimental comparisons imply that high-power microwave irradiation can reduce the fracturing time of hard rock and that the fracture range (160 mm) of a 915-MHz microwave source is about three times that of 2.45 GHz. After microwave-induced borehole fracturing, many tensile cracks occur on the rock surface and in the borehole: the maximum reduction of the P-wave velocity is 12.8%. The test results show that a high-power microwave source of 915 MHz is more conducive to assisting mechanical rock breaking and destressing. The system can promote the development of microwave-assisted rock breaking equipment.展开更多
We present a new method that can be used to calculate pulse-front distortion by measuring the spectral interference of two point-diffraction fields in their overlapped district. We demonstrate, for the first time, the...We present a new method that can be used to calculate pulse-front distortion by measuring the spectral interference of two point-diffraction fields in their overlapped district. We demonstrate, for the first time, the measurement of the pulse-front distortion of the pulse from a complex multi-pass amplification system, which exists in almost all high-power laser systems, and obtain the irregular pulse-front distribution. The method presented does not need any reference light or assumption about the pulse-front distribution, and has an accuracy of several femtoseconds.展开更多
We report high-power single-spatial-mode type-I GaSb-based tapered lasers fabricated on the InGaSb/AlGaAsSb material system. A straight ridge and three different tapered waveguide structures with varying flare angles ...We report high-power single-spatial-mode type-I GaSb-based tapered lasers fabricated on the InGaSb/AlGaAsSb material system. A straight ridge and three different tapered waveguide structures with varying flare angles are fabricated to optimize the output power and spatial-mode performance. The best devices exhibit single-spatial-mode operation with room-temperature output power up to 350？mW in continuous-wave mode at an emission wavelength around 2.0？μm with a very small far-field lateral divergence angle, which is beyond state of the art in terms of single-spatial-mode output power.展开更多
The latch-up effect induced by high-power microwave（HPM） in complementary metal–oxide–semiconductor（CMOS） inverter is investigated in simulation and theory in this paper. The physical mechanisms of excess carrie...The latch-up effect induced by high-power microwave（HPM） in complementary metal–oxide–semiconductor（CMOS） inverter is investigated in simulation and theory in this paper. The physical mechanisms of excess carrier injection and HPM-induced latch-up are proposed. Analysis on upset characteristic under pulsed wave reveals increasing susceptibility under shorter-width pulsed wave which satisfies experimental data, and the dependence of upset threshold on pulse repetitive frequency（PRF） is believed to be due to the accumulation of excess carriers. Moreover, the trend that HPMinduced latch-up is more likely to happen in shallow-well device is proposed.Finally, the process of self-recovery which is ever-reported in experiment with its correlation with supply voltage and power level is elaborated, and the conclusions are consistent with reported experimental results.展开更多
An effect of the high-power electromagnetic pulses onto the droplet of coal-water slurry inside the furnace was investigated.In contrary to the previously investigated laser-induced fuel atomization that occurs at the...An effect of the high-power electromagnetic pulses onto the droplet of coal-water slurry inside the furnace was investigated.In contrary to the previously investigated laser-induced fuel atomization that occurs at the room temperature,the pre-heated(to 400 K)slurry becomes dry enough to prevent the explosion-like steam formation.Thus,fuel does not atomize and the ignition does not accelerate.Furthermore,the absorption of several laser pulses leads to evident sintering of irradiated surface with following increase of the ignition delay time for up to 24%.Variation of the pulse energy in range 48-118 mJ(corresponding intensity up to 2.4 J·cm^-2)leads to certain variation of the increase of ignition delay.The strong pulsed overheating of the coal water slurry which does not initiate the fine atomization of the fuel generally makes its ignition longer.展开更多
基金supported by the National Key Research and Development Program of China(No.2023YFF0720700)the National Natural Science Foundation of China(Nos.52032010 and 52272120)the Central Government Funds of Guiding Local Scientific and Technological Development for Sichuan Province(No.2022ZYD0018).
文摘The types of dopants lead to distinctive microstructural evolution behavior and physical properties in materials.In this study,the effect of stoichiometric and non-stoichiometric Mn modification,namely Pb(Mn_(1/3) Nb_(2/3))O_(3)(PMnN)and MnO_(2),on the microstructure and properties of Pb(Yb_(1/2) Nb_(1/2))O_(3)-PbZrO_(3)-PbTiO_(3)(PYN-PZT)piezoelectric ceramics are systematically investigated.It was found that stoichiometric PMnN modification inhibits the grain growth while non-stoichiometric MnO_(2) modification promotes it,and thus the former yields stronger high-power characteristics(higher internal bias field Ei and larger mechanical quality factor Q_(m))than the latter.Specifically,with an equivalent amount of Mn modifica-tion(2 mol%),PMnN and MnO_(2) modification PYN-PZT ceramics exhibit significantly different values for average grain size(1.21μm vs.14.12μm),Ei(8.5 kV/cm vs.5 kV/cm),and Qm(2376 vs.1134).To further evaluate high-power performance,the vibration velocity v of these two modified PYN-PZT under high driving conditions was measured.Under an AC electric field of 3.5 V/mm,the PYN-PZT+6PMnN ceram-ics exhibit a v of up to 0.95 m s^(−1),larger than both MnO2-doped PYN-PZT(0.72 m s^(−1))and unmodified PYN-PZT ceramics(0.1 m s^(−1)),and far outperformance than both PZT-4 and PZT-8 ceramics.Furthermore,to elucidate the origin of the exceptional high-power performance of PMnN-modified PYN-PZT,we per-formed phase-field simulations revealing a pinning effect of the grain boundary on domain wall motion.Consequently,the small grain size(high grain boundary density)in PMnN-modified PYN-PZT exhibits a strong pinning effect,resulting in a large Q_(m) and outstanding high-power performance.
基金Research and Development Project on Voltage Sensors by China Southern Power Grid Digital Research Institute(210000KK52220017)。
文摘Lead magnesium niobate-lead titanate(PMN-PT)piezoelectric single crystals are widely utilized due to their outstanding performance,with varying compositions significantly impacting their properties.While application of PMN-PT in high-power settings is rapidly evolving,material parameters are typically tested under low signal conditions(1 V),and effects of different PT(PbTiO_(3))contents on the performance of PMN-PT single crystals under high-power conditions remain unclear.This study developed a comprehensive high-power testing platform using the constant voltage method to evaluate performance of PMN-PT single crystals with different PT contents under high-power voltage stimulation.Using crystals sized at 10 mm×3 mm×0.5 mm as an example,this research explored changes in material parameters.The results exhibit that while trend of the parameter changes under high-power excitation was consistent across different PT contents,degree of the change varied significantly.For instance,a PMN-PT single crystal with 26%(in mol)PT content exhibited a 25%increase in the piezoelectric coefficient d_(31),a 13%increase in the elastic compliance coefficient s_(11)^(E),a 17%increase in the electromechanical coupling coefficient k_(31),and a 73%decrease in the mechanical quality factor Q_(m) when the power reached 7.90 W.As the PT content increased,the PMN-PT materials became more susceptible to temperature influences,significantly reducing the power tolerance and more readily reaching the depolarization temperatures.This led to loss of piezoelectric performance.Based on these findings,a clearer understanding of impact of PT content on performance of PMN-PT single crystals under high-power applications has been established,providing reliable data to support design of sensors or transducers using PMN-PT as the sensitive element.
基金supported by the National Key Research and Development Program of China(2018YFC0604102)the project of China Geological Survey(DD20190015)。
文摘The Jiama porphyry copper deposit in Xizang is one of the proven supergiant copper deposits in the Qinghai-Tibet Plateau at present,with the reserves of geological resources equivalent to nearly 20×10^(6)t.However,it features wavy and steep terrain,leading to extremely difficult field operation and heavy interference.This study attempts to determine the effects of the tensor controlled-source audiomagnetotellurics(CSAMT)with high-power orthogonal signal sources(also referred to as the high-power tensor CSAMT)when it is applied to the deep geophysical exploration in plateaus with complex terrain and mining areas with strong interference.The test results show that the high current provided by the highpower tensor CSAMT not only greatly improved the signal-to-noise ratio but also guaranteed that effective signals were received in the case of a long transmitter-receiver distance.Meanwhile,the tensor data better described the anisotropy of deep geologic bodies.In addition,the tests also show that when the transmitting current reaches 60 A,it is still guaranteed that strong enough signals can be received in the case of the transmitter-receiver distance of about 25 km,sounding curves show no near field effect,and effective exploration depth can reach 3 km.The 2D inversion results are roughly consistent with drilling results,indicating that the high-power tensor CSAMT can be used to achieve nearly actual characteristics of underground electrical structures.Therefore,this method has great potential for application in deep geophysical exploration in plateaus and mining areas with complex terrain and strong interference,respectively.This study not only serves as important guidance on the prospecting in the Qinghai-Tibet Plateau but also can be used as positive references for deep mineral exploration in other areas.
文摘High-power laser technology is widely used in manufacturing processing,medical diagnosis,and treatment,and is one of the important fields of strategic high-tech competition in China at the moment.In the context of industrial upgrading,high-power laser technology plays an important role in leading the development of the manufacturing industry and industrial intelligence.Based on this,this paper carries out research on high-power laser technology and industry,summarizes the basic principle and classification of high-power laser technology,analyzes the current status of high-power laser technology industry,points out the opportunities and challenges faced by the industry development,puts forward suggestions to promote the development of high-power laser technology industry,and to provide an effective reference for the application and development of high-power laser technology.
文摘The growing demand for efficient high-power switching power supplies has spurred interest in advanced topologies.The three-phase VIENNA converter stands out for its high power factor,simplified structure,and robust performance.Current research focuses on its operational principles,control strategies,and behavior under various load conditions.Key considerations include component selection,thermal management,and EMI/EMC optimization.This topology finds applications across renewable energy systems,industrial equipment,telecommunications,and electric vehicle charging infrastructures.Comparative analyses with alternative topologies and cost-benefit evaluations are also addressed.Future developments are expected to emphasize the integration of wide-bandgap devices and advancements in digital control techniques to further enhance efficiency and system performance.
基金supported by the Open Fund of Magnetic Confinement Fusion Laboratory of Anhui Province(No.2024AMF04003)the Natural Science Foundation of Anhui Province(No.228085ME142)Comprehensive Research Facility for Fusion Technology(No.20180000527301001228)。
文摘This research focuses on solving the fault detection and health monitoring of high-power thyristor converter.In terms of the critical role of thyristor converter in nuclear fusion system,a method based on long short-term memory(LSTM)neural network model is proposed to monitor the operational state of the converter and accurately detect faults as they occur.By sampling and processing a large number of thyristor converter operation data,the LSTM model is trained to identify and detect abnormal state,and the power supply health status is monitored.Compared with traditional methods,LSTM model shows higher accuracy and abnormal state detection ability.The experimental results show that this method can effectively improve the reliability and safety of the thyristor converter,and provide a strong guarantee for the stable operation of the nuclear fusion reactor.
基金Project (51175095) supported by the National Natural Science Foundation of ChinaProjects (10251009001000001,9151009001000020) supported by the Natural Science Foundation of Guangdong Province,ChinaProject (20104420110001) supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China
文摘Classification of plume and spatter images was studied to evaluate the welding stability. A high-speed camera was used to capture the instantaneous images of plume and spatters during high power disk laser welding. Characteristic parameters such as the area and number of spatters, the average grayscale of a spatter image, the entropy of a spatter grayscale image, the coordinate ratio of the plume centroid and the welding point, the polar coordinates of the plume centroid were defined and extracted. Karhunen-Loeve transform method was used to change the seven characteristics into three primary characteristics to reduce the dimensions. Also, K-nearest neighbor method was used to classify the plume and spatter images into two categories such as good and poor welding quality. The results show that plume and spatter have a close relationship with the welding stability, and two categories could be recognized effectively using K-nearest neighbor method based on Karhunen-Loeve transform.
基金Project supported by the National Key Laboratory Foundation,China(Grant No.9140C530103110C5301)
文摘Based on the particle-in-cell technology and the secondary electron emission theory, a three-dimensional simulation method for multipactor is presented in this paper. By combining the finite difference time domain method and the panicle tracing method, such an algorithm is self-consistent and accurate since the interaction between electromagnetic fields and particles is properly modeled. In the time domain aspect, the generation of multipactor can be easily visualized, which makes it possible to gain a deeper insight into the physical mechanism of this effect. In addition to the classic secondary electron emission model, the measured practical secondary electron yield is used, which increases the accuracy of the algorithm. In order to validate the method, the impedance transformer and ridge waveguide filter are studied. By analyzing the evolution of the secondaries obtained by our method, multipactor thresholds of these components are estimated, which show good agreement with the experimental results. Furthermore, the most sensitive positions where multipactor occurs are determined from the phase focusing phenomenon, which is very meaningful for multipactor analysis and design.
文摘To improve the characteristics of a diamond-like carbon （DLC） film, Ti-containing amorphous hydrogenated carbon thin films were deposited on sus304 stainless steel substrates by high-power plasma-sputtering with titanium metal as the solid plasma source in a mixed ArC2H2 atmosphere. The films were fabricated to obtain a multilayered structure of Ti/TiC/DLC gradient for improving adhesion and reducing residual stress. The effects of substrate bias and target-substrate distance on the films＇ properties were studied by glow discharge spectroscope, X-ray diffractometer, Raman spectroscope, nanoindenter, and a pin-on-disk tribometer. The results indicate that the films possess superior adhesive strength and toughness.
文摘A two-dimensional model of the silicon NPN monolithic composite transistor is established for the first time by utilizing the semiconductor device simulator, Sentaurus-TCAD. By analyzing the internal distributions of electric field, current density, and temperature of the device, a detailed investigation on the damage process and mechanism induced by high-power microwaves （HPM） is performed. The results indicate that the temperature elevation occurs in the negative half-period and the temperature drop process is in the positive half-period under the HPM injection from the output port. The damage point is located near the edge of the base-emitter junction of T2, while with the input injection it exists between the base and the emitter of T2. Comparing these two kinds of injection, the input injection is more likely to damage the device than the output injection. The dependences of the damage energy threshold and the damage power threshold causing the device failure on the pulse-width are obtained, and the formulas obtained have the same form as the experimental equations, which demonstrates that more power is required to destroy the device if the pulse-width is shorter. Furthermore, the simulation result in this paper has a good coincidence with the experimental result.
基金Key Scientific and Technological Research Projects of Henan Province(072102240027)Dr Foundation of Henan Polytechnic University(648602)Postgraduate Degree Thesis Innovation Foundation of Henan Polytechnic University(644005)
文摘Thermal management is one of the key technologies for high-power Light emitting diode(LED)entering into the general illuminating field.Successful thermal management depends on optimal packaging structure and selected packaging materials.In this paper,the aluminum is employed as a substrate of LED,3×3 array chips are placed on the substrate,heat dissipation performance is simulated using finite element analysis(FEA)software,analyzed are the influences on the temperature of the chip with different convection coefficient,and optical properties are simulated using optical analysis software.The results show that the packaging structure can not only effectually improve the thermal performance of high-power LED array but also increase the light extraction efficiency.
基金Project supported by Yifang Wang’s Science Studio of the Ten Thousand Talents Project。
文摘To reduce the energy demand and operation cost for circular electron positron collider(CEPC), the high efficiency klystrons are being developed at Institute of High Energy Physics, Chinese Academy of Sciences. A 800-k W continuous wave(CW) klystron operating at frequency of 650-MHz has been designed. The results of beam–wave interaction simulation with several different codes are presented. The efficiency is optimized to be 65% with a second harmonic cavity in three-dimensional(3D) particle-in-cell code CST. The effect of cavity frequency error and mismatch load on efficiency of klystron have been investigated. The design and cold test of reentrant cavities are described, which meet the requirements of RF section design. So far, the manufacturing and high-power test of the first klystron prototype have been completed.When the gun operated at DC voltage of 80 k V and current of 15.4 A, the klystron peak power reached 804 k W with output efficiency of about 65.3% at 40% duty cycle. The 1-d B bandwidth is ±0.8 MHZ. Due to the crack of ceramic window, the CW power achieved about 700 kW. The high-power test results are in good agreement with 3D simulation.
基金support from the Na-tional Natural Science Foundation of China(Grant No.41827806)the liaoning Revitalization Talent Program of China(Grant No.XLYCYSZX1902).
文摘Microwave pre-treatment is considered as a promising technique for alleviating cutter wear. This paper introduces a high-power microwave-induced fracturing system for hard rock. The test system consists of a high-power microwave subsystem (100 kW), a true triaxial testing machine, a dynamic monitoring subsystem, and an electromagnetic shielding subsystem. It can realize rapid microwave-induced fracturing, intelligent tuning of impedance, dynamic feedback under strong microwave fields, and active control of microwave parameters by addressing the following issues: the instability and insecurity of the system, the discharge breakdown between coaxial lines during high-power microwave output, and a lack of feedback of rock-microwave response. In this study, microwave-induced surface and borehole fracturing tests under true triaxial stress were carried out. Experimental comparisons imply that high-power microwave irradiation can reduce the fracturing time of hard rock and that the fracture range (160 mm) of a 915-MHz microwave source is about three times that of 2.45 GHz. After microwave-induced borehole fracturing, many tensile cracks occur on the rock surface and in the borehole: the maximum reduction of the P-wave velocity is 12.8%. The test results show that a high-power microwave source of 915 MHz is more conducive to assisting mechanical rock breaking and destressing. The system can promote the development of microwave-assisted rock breaking equipment.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 10904132 and 11074225)the National Defense Science Technology Foundation of State Key Laboratory of High Temperature and Density Plasma Physics,China (Grant No. 9140C680604110C6805)
文摘We present a new method that can be used to calculate pulse-front distortion by measuring the spectral interference of two point-diffraction fields in their overlapped district. We demonstrate, for the first time, the measurement of the pulse-front distortion of the pulse from a complex multi-pass amplification system, which exists in almost all high-power laser systems, and obtain the irregular pulse-front distribution. The method presented does not need any reference light or assumption about the pulse-front distribution, and has an accuracy of several femtoseconds.
基金Supported by the National Basic Research Program of China under Grant Nos 2014CB643903 and 2013CB932904the National Natural Science Foundation of China under Grant Nos 61435012 and 61290303the Strategic Priority Research Program(B) of the Chinese Academy of Sciences under Grant No XDB01010200
文摘We report high-power single-spatial-mode type-I GaSb-based tapered lasers fabricated on the InGaSb/AlGaAsSb material system. A straight ridge and three different tapered waveguide structures with varying flare angles are fabricated to optimize the output power and spatial-mode performance. The best devices exhibit single-spatial-mode operation with room-temperature output power up to 350？mW in continuous-wave mode at an emission wavelength around 2.0？μm with a very small far-field lateral divergence angle, which is beyond state of the art in terms of single-spatial-mode output power.
基金Project supported by the Open Fund of Key Laboratory of Complex Electromagnetic Environment Science and Technology,China Academy of Engineering Physics(Grant No.2015-0214.XY.K)
文摘The latch-up effect induced by high-power microwave（HPM） in complementary metal–oxide–semiconductor（CMOS） inverter is investigated in simulation and theory in this paper. The physical mechanisms of excess carrier injection and HPM-induced latch-up are proposed. Analysis on upset characteristic under pulsed wave reveals increasing susceptibility under shorter-width pulsed wave which satisfies experimental data, and the dependence of upset threshold on pulse repetitive frequency（PRF） is believed to be due to the accumulation of excess carriers. Moreover, the trend that HPMinduced latch-up is more likely to happen in shallow-well device is proposed.Finally, the process of self-recovery which is ever-reported in experiment with its correlation with supply voltage and power level is elaborated, and the conclusions are consistent with reported experimental results.
基金performed within the framework of the Russian State Assignment“Science”project FSWW-2020-0022Investigations of the ignition techniques of waste-derived fuels were partially supported by the Tomsk Polytechnic University Competitiveness Enhancement Program(project VIU-ISHFVP-197/2019).
文摘An effect of the high-power electromagnetic pulses onto the droplet of coal-water slurry inside the furnace was investigated.In contrary to the previously investigated laser-induced fuel atomization that occurs at the room temperature,the pre-heated(to 400 K)slurry becomes dry enough to prevent the explosion-like steam formation.Thus,fuel does not atomize and the ignition does not accelerate.Furthermore,the absorption of several laser pulses leads to evident sintering of irradiated surface with following increase of the ignition delay time for up to 24%.Variation of the pulse energy in range 48-118 mJ(corresponding intensity up to 2.4 J·cm^-2)leads to certain variation of the increase of ignition delay.The strong pulsed overheating of the coal water slurry which does not initiate the fine atomization of the fuel generally makes its ignition longer.
