Germanium(Ge)-air battery,a new type of semiconductor-air battery,has garnered increasing attention owing to its environmental friendliness,safety,and excellent dynamic performance.However,the flat Ge anode is prone t...Germanium(Ge)-air battery,a new type of semiconductor-air battery,has garnered increasing attention owing to its environmental friendliness,safety,and excellent dynamic performance.However,the flat Ge anode is prone to passivation,owing to GeO_(2) accumulation on its surface,resulting in premature discharge termination.In this study,various nano-Ge pyramid structures(GePS)were prepared using chemical etching(CE)and metal-assisted chemical etching(MACE)methods to enhance the specific surface area of the Ge anode,thereby facilitating the dissolution of the passivation layer.This study revealed that the MACE method significantly accelerated the etching rate of the Ge surface,producing exceptional GePS.Furthermore,Ge-air batteries employing Ge anodes prepared using MACE demonstrated an exceptional discharge life of up to 9240 h(385 days).The peak power density reached 3.03mW/cm^(2),representing improvements of more than 2 times and 1.8 times,respectively,compared with batteries using flat Ge anodes.This study presents a straightforward approach to enhance Ge anode performance,thereby expanding the potential applications of Ge-air batteries.展开更多
To describe the complex kinetics of formation and destruction mechanism of nitrogen dioxide（NO2）, there is an increasing demand for real-time and in situ analysis of NO2 in the discharge region. Pulsed cavity ring-d...To describe the complex kinetics of formation and destruction mechanism of nitrogen dioxide（NO2）, there is an increasing demand for real-time and in situ analysis of NO2 in the discharge region. Pulsed cavity ring-down spectroscopy（CRDS） provides an excellent diagnostic approach. In the present paper, CRDS has been applied in situ for time evolution measurement of NO2 concentration which is rarely investigated in gas discharges. In pulsed direct current discharge of NO2/Ar mixture at a pressure of 500 Pa, a peak voltage of -1300 V and a frequency of 30 Hz, for higher initial NO2 concentration（3.05×10^（14）cm^（-3）, 8.88×10^（13）cm^（-3））,the NO2 concentration sharply decreases at the beginning of the discharge afterglow and then becomes almost constant, and the pace of decline increases with pulse duration; however, for lower initial NO2 concentration of 1.69×10^（13）cm^（-3）, the NO2 concentration also decreases at the beginning of the discharge afterglow for 200 ns and 1 μs pulse durations, while it slightly increases and then declines for 2 μs pulse duration. Thus, the removal of low-level NO2 could not be promoted by a higher mean energy input.展开更多
The rapid development of capacitors with high energy density and efficiency has been driven by advanced electronic systems and innovative pulsed power applications.In this study,we prepared Sr_(4.5−x)Ba_(x)Sm_(0.5)Zr_...The rapid development of capacitors with high energy density and efficiency has been driven by advanced electronic systems and innovative pulsed power applications.In this study,we prepared Sr_(4.5−x)Ba_(x)Sm_(0.5)Zr_(0.5)Nb_(9.5)O_(30)(x=2.5,3,3.5,4,4.5)dielectric ceramics,which exhibited structural distortion due to the co-occupation of Ba^(2+),Sr^(2+),and Sm^(3+)in the A-site and the partial substitution of Nb^(5+)by Zr^(4+)in the B-site.The ordered/disordered distribution due to these distortions thus generated polar nanoregions(PNRs)and induced a relaxation ferroelectric behavior,which was verified by the high-resolution transmission electron microscopy.Through the use of the Vogel–Fulcher and Maxwell–Boltzmann equations,we found that easy inversion and small dipole sizes are crucial for achieving high energy storage density and efficiency.The Sr_(4.5−x)Ba_(x)Sm_(0.5)Zr_(0.5)Nb_(9.5)O_(30)(x=3.5)dielectric ceramic displayed a ferroelectric/paraelectric transition near room temperature.Subsequent ferroelectric testing revealed large energy storage density(Wrec=4.31 J·cm^(−3))and high efficiency(η=93.8%)at 310 kV·cm−1.Furthermore,Sr_(4.5−x)Ba_(x)Sm_(0.5)Zr_(0.5)Nb_(9.5)O_(30)(x=4.5)exhibited higher breakdown field strength due to its large resistivity and small grain size.This led to energy storage density of approximately 5.3 J·cm^(−3)at 460 kV·cm^(−1).Additionally,Sr_(4.5−x)Ba_(x)Sm_(0.5)Zr_(0.5)Nb_(9.5)O_(30)(x=3.5)demonstrated current density(CD)of approximately 713.38 A·cm^(−2)and power density(PD)of approximately 87.51 MW·cm^(−3),with ultrafast discharge time of 34 ns and excellent discharge energy density(Wdis)of approximately 2.27 J·cm^(−3).Overall,this study presents a promising approach for developing dielectric ceramic materials that hold potential for applications in innovative pulsed power components.展开更多
The effects of nanosecond discharge on ignition characteristics of a stoichiometric methane–air mixture without inert diluent gas were studied by numerical simulation at 0.1 MPa and an initial temperature of 1300 K. ...The effects of nanosecond discharge on ignition characteristics of a stoichiometric methane–air mixture without inert diluent gas were studied by numerical simulation at 0.1 MPa and an initial temperature of 1300 K. A modified non-equilibrium plasma kinetic model was developed to simulate the temporal evolution of particles produced during nanosecond discharge and its afterglow. As important roles in ignition, path fluxes of O and H radicals were analyzed in detail. Different strength of E/N and different discharge duration were applied to the discharge process in this study. And the results presented that a deposited energy of 1–30 m J·cm^(-3) could dramatically reduce the ignition delay time. Furthermore, temperature and radicals analysis was conducted to investigate the effect of non-equilibrium plasma on production of intermediate radicals. Finally, sensitivity analysis was employed to have further understanding on ignition chemistries of the mixture under nanosecond discharge.展开更多
The effects of the Xe gas content and total gas pressure on the discharge characteristics of colour plasma display panels including the sustaining voltage margin, white-field chromaticity, discharge time lag （DTL）, ...The effects of the Xe gas content and total gas pressure on the discharge characteristics of colour plasma display panels including the sustaining voltage margin, white-field chromaticity, discharge time lag （DTL）, discharge current peak, and full-width-at-half-maximum （FWHM） of the discharge current pulse, are experimentally studied. The results indicate that as the Xe gas content in the He-Ne-Xe gas mixture or total pressure increases, the sustaining voltage margin increases, the white-field chromaticity improves, and the discharge current peak has a maximum value, while DTL and FWHM have a minimum value. The mean electron energy in the gas mixture discharge is also calculated through a numerical solution of Boltzmann equation. The experimental results are explained from a view of the mean electron energy variations with the Xe gas content and total gas pressure.展开更多
Low energy arc discharge characteristics was analyzed based on dynamic V-A characteristics model. It draws conclusions that discharge time relates to the source voltage and the product of inductance and stable current...Low energy arc discharge characteristics was analyzed based on dynamic V-A characteristics model. It draws conclusions that discharge time relates to the source voltage and the product of inductance and stable current, discharge time will increase when the source voltage increases; current reduce rate is in inverse proportion to the value of inductance; arc resistance when the arc occurs is the ratio of minimum arcing voltage to stable current. It also gains the expressions of arc resistance and arc power, arc resistance and arc power both increase as the source voltage increases and decrease as the value of inductance increases. Conclusions above mentioned are helpful to design intrinsically safe circuits.展开更多
BACKGROUND Laparoscopic nephrectomy is a preferred surgical approach due to its minimally invasive nature and faster recovery times.However,effective management of postoperative pain remains a significant challenge.Se...BACKGROUND Laparoscopic nephrectomy is a preferred surgical approach due to its minimally invasive nature and faster recovery times.However,effective management of postoperative pain remains a significant challenge.Several traditional methods,including opioid-based analgesia,are commonly used but are associated with side effects such as nausea,vomiting,sedation,and delayed recovery.In recent years,the erector spinae plane block(ESPB)has gained attention as an ultrasoundguided regional anesthesia technique offering promising results in various surgical procedures by reducing opioid requirements and enhancing patient comfort.AIM To evaluate the efficacy and safety of ESPB in comparison to conventional pain management strategies in patients undergoing laparoscopic nephrectomy.METHODS Following PRISMA guidelines,we searched PubMed,EMBASE,Web of Science,and the Cochrane Register for randomized controlled trials(RCTs)comparing ESPB with control for laparoscopic nephrectomy.The Cochrane Risk of Bias tool was employed for quality assessment.The primary outcome was total patient-controlled analgesia(PCA)consumption.Secondary outcomes included hospital discharge time and the incidence of postoperative nausea and vomiting.A random-effects meta-analysis was conducted to calculate pooled mean differences(MD)and odds ratios(OR)with 95%CIs.RESULTS Nine RCTs involving a total of 643 patients(ESPB group=320;control group=323)were included in the analysis.ESPB significantly reduced PCA opioid consumption compared to controls(MD:-14.24,95%CI:-20.66 to-7.83,P<0.0001).Subgroup analysis showed reduced PCA use with ESPB vs morphine(MD:-8.78,95%CI:-15.34 to-2.22,P=0.009),and a non-significant effect compared to other analgesics(MD:-48.26,95%CI:-143.60 to 47.09).No statistically significant differences were observed in discharge time or the incidence of nausea and vomiting.CONCLUSION ESPB demonstrates the potential of reducing PCA in laparoscopic nephrectomy patients;however,its impact on secondary outcomes remains inconclusive.Large-scale RCTs are needed to confirm ESPB's benefits and explore long-term effects.展开更多
Space ion electric propulsion has been widely used in the north-south position maintenance and orbit transfer missions for high-orbit satellites.However,unexpected electric breakdown by ion electric propulsion systems...Space ion electric propulsion has been widely used in the north-south position maintenance and orbit transfer missions for high-orbit satellites.However,unexpected electric breakdown by ion electric propulsion systems is still a challenging problem that needs to be solved,as it affects reliability.Based on the analysis of in-orbit and ground test data of ion thrusters from simulation and experimental results,the main influencing factors of induced electric breakdown are clarified and the mechanisms of induced electric breakdown are analyzed.It is found that the main factors inducing breakdown are the voltage and electric field strength between the grids.In addition,by monitoring the waveform of plasma discharge,the temporal characteristics of breakdown can be defined as three stages of“breakdown-spark-loop response”.Thus,three kinds of engineering suppression methods for breakdown of static vacuum with periodic short-term heating,electrode surface polishing and sealing insulation with plasma,add energy suppression circuit are carried out,and the experimental results show that the electric breakdown frequency can be reduced by about 30%.展开更多
In order to apply ultra-fine water mist technology on spontaneous coal combustion in the goaf of a coal mine,we built a small scale compartment with ultra-fine water mist for restraining coal combustion in a confined ...In order to apply ultra-fine water mist technology on spontaneous coal combustion in the goaf of a coal mine,we built a small scale compartment with ultra-fine water mist for restraining coal combustion in a confined space and then investigated the restraining efficiency and related factors.The study obtained the following results:a descending rate of heat release,an increase in O_(2),the production of CO_(2)decreased gradually,while the production of CO increased dramatically and quickly and then decreased;ultimately it tended to become stable after the discharge of an ultra-fine water mist.The technology showed that the ultra-fine water mist can effectively reduce the heat release rate of coal and the rate to generate components.We found that the restraining effect relied on the mist flux,the discharge time and other factors.A sufficient amount of mist has a better effect compared to an insufficient amount of mist.To combat coal combustion,the greater the discharge time,the better coal flames are extinguished.展开更多
Triggering characteristics of triggered vacuum switch （TVS）, including the discharge delay time, delay jitter, range of operational voltage and peak of pulsed current, are investigated. Both structure and experiment...Triggering characteristics of triggered vacuum switch （TVS）, including the discharge delay time, delay jitter, range of operational voltage and peak of pulsed current, are investigated. Both structure and experimental circuit of TVS are presented. The results indicate that TVS, as a surface flashover triggering device with high dielectric permittivity material, is with excellent triggering characteristics. When the hold-off voltage reaches 120 kV, the minimum operational voltage is 1.3 kV, and the minimum discharge delay time and jitter are 100 ns and ±10 ns, respectively. The peak current is up to 240 kA when the operational voltage reaches 100 kV. TVS can well satisfy the main demands of high voltage and current applications, and can also be used under a multi-crowbar circuit.展开更多
An analytical description for guiding of ions through nanocapillaries is given on the basis of previous work. The current entering into the capillary is assumed to be divided into a current fraction transmitted throug...An analytical description for guiding of ions through nanocapillaries is given on the basis of previous work. The current entering into the capillary is assumed to be divided into a current fraction transmitted through the capillary, a current fraction flowing away via the capillary conductivity and a current fraction remaining within the capillary, which is responsible for its charge-up. The discharging current is assumed to be governed by the Frenkel–Poole process. At higher conductivities the analytical model shows a blocking of the ion transmission, which is in agreement with recent simulations.Also, it is shown that ion blocking observed in experiments is well reproduced by the analytical formula. Furthermore, the asymptotic fraction of transmitted ions is determined. Apart from the key controlling parameter(charge-to-energy ratio), the ratio of the capillary conductivity to the incident current is included in the model. Differences resulting from the nonlinear and linear limits of the Frenkel–Poole discharge are pointed out.展开更多
基金financially supported by the National Natural Science Foundation of China(No.61904073)Spring City Plan-Special Program for Young Talents(No.K202005007)+2 种基金Yunnan Talents Support Plan for Yong Talents(No.XDYC-QNRC-2022-0482)Yunnan Local Colleges Applied Basic Research Projects(No.202101BA070001-138)Frontier Research Team of Kunming University 2023.
文摘Germanium(Ge)-air battery,a new type of semiconductor-air battery,has garnered increasing attention owing to its environmental friendliness,safety,and excellent dynamic performance.However,the flat Ge anode is prone to passivation,owing to GeO_(2) accumulation on its surface,resulting in premature discharge termination.In this study,various nano-Ge pyramid structures(GePS)were prepared using chemical etching(CE)and metal-assisted chemical etching(MACE)methods to enhance the specific surface area of the Ge anode,thereby facilitating the dissolution of the passivation layer.This study revealed that the MACE method significantly accelerated the etching rate of the Ge surface,producing exceptional GePS.Furthermore,Ge-air batteries employing Ge anodes prepared using MACE demonstrated an exceptional discharge life of up to 9240 h(385 days).The peak power density reached 3.03mW/cm^(2),representing improvements of more than 2 times and 1.8 times,respectively,compared with batteries using flat Ge anodes.This study presents a straightforward approach to enhance Ge anode performance,thereby expanding the potential applications of Ge-air batteries.
基金supported by National Natural Science Foundation of China(Nos.11175035,11405022,11475039,11605023)the National Magnetic Confinement Fusion Science Program of China(No.2013GB109005)+2 种基金Chinesisch-Deutsches Forschungsprojekt(No.GZ768)the Fundamental Research Funds for the Central Universities(Nos.DUT14ZD(G)04,DUT15RC(3)072,DUT15TD44,DUT16TD13)China Postdoctoral Science Foundation(No.2016M591423)
文摘To describe the complex kinetics of formation and destruction mechanism of nitrogen dioxide（NO2）, there is an increasing demand for real-time and in situ analysis of NO2 in the discharge region. Pulsed cavity ring-down spectroscopy（CRDS） provides an excellent diagnostic approach. In the present paper, CRDS has been applied in situ for time evolution measurement of NO2 concentration which is rarely investigated in gas discharges. In pulsed direct current discharge of NO2/Ar mixture at a pressure of 500 Pa, a peak voltage of -1300 V and a frequency of 30 Hz, for higher initial NO2 concentration（3.05×10^（14）cm^（-3）, 8.88×10^（13）cm^（-3））,the NO2 concentration sharply decreases at the beginning of the discharge afterglow and then becomes almost constant, and the pace of decline increases with pulse duration; however, for lower initial NO2 concentration of 1.69×10^（13）cm^（-3）, the NO2 concentration also decreases at the beginning of the discharge afterglow for 200 ns and 1 μs pulse durations, while it slightly increases and then declines for 2 μs pulse duration. Thus, the removal of low-level NO2 could not be promoted by a higher mean energy input.
基金the National Natural Science Foundation of China(No.12164012)the Science and Technology Major Project of Guangxi(No.AA21077012)for financial support.
文摘The rapid development of capacitors with high energy density and efficiency has been driven by advanced electronic systems and innovative pulsed power applications.In this study,we prepared Sr_(4.5−x)Ba_(x)Sm_(0.5)Zr_(0.5)Nb_(9.5)O_(30)(x=2.5,3,3.5,4,4.5)dielectric ceramics,which exhibited structural distortion due to the co-occupation of Ba^(2+),Sr^(2+),and Sm^(3+)in the A-site and the partial substitution of Nb^(5+)by Zr^(4+)in the B-site.The ordered/disordered distribution due to these distortions thus generated polar nanoregions(PNRs)and induced a relaxation ferroelectric behavior,which was verified by the high-resolution transmission electron microscopy.Through the use of the Vogel–Fulcher and Maxwell–Boltzmann equations,we found that easy inversion and small dipole sizes are crucial for achieving high energy storage density and efficiency.The Sr_(4.5−x)Ba_(x)Sm_(0.5)Zr_(0.5)Nb_(9.5)O_(30)(x=3.5)dielectric ceramic displayed a ferroelectric/paraelectric transition near room temperature.Subsequent ferroelectric testing revealed large energy storage density(Wrec=4.31 J·cm^(−3))and high efficiency(η=93.8%)at 310 kV·cm−1.Furthermore,Sr_(4.5−x)Ba_(x)Sm_(0.5)Zr_(0.5)Nb_(9.5)O_(30)(x=4.5)exhibited higher breakdown field strength due to its large resistivity and small grain size.This led to energy storage density of approximately 5.3 J·cm^(−3)at 460 kV·cm^(−1).Additionally,Sr_(4.5−x)Ba_(x)Sm_(0.5)Zr_(0.5)Nb_(9.5)O_(30)(x=3.5)demonstrated current density(CD)of approximately 713.38 A·cm^(−2)and power density(PD)of approximately 87.51 MW·cm^(−3),with ultrafast discharge time of 34 ns and excellent discharge energy density(Wdis)of approximately 2.27 J·cm^(−3).Overall,this study presents a promising approach for developing dielectric ceramic materials that hold potential for applications in innovative pulsed power components.
基金Supported by the National Natural Science Foundation of China(No.51376021)the Fundamental Research Funds for the Central Universities(No.2015YJS146)
文摘The effects of nanosecond discharge on ignition characteristics of a stoichiometric methane–air mixture without inert diluent gas were studied by numerical simulation at 0.1 MPa and an initial temperature of 1300 K. A modified non-equilibrium plasma kinetic model was developed to simulate the temporal evolution of particles produced during nanosecond discharge and its afterglow. As important roles in ignition, path fluxes of O and H radicals were analyzed in detail. Different strength of E/N and different discharge duration were applied to the discharge process in this study. And the results presented that a deposited energy of 1–30 m J·cm^(-3) could dramatically reduce the ignition delay time. Furthermore, temperature and radicals analysis was conducted to investigate the effect of non-equilibrium plasma on production of intermediate radicals. Finally, sensitivity analysis was employed to have further understanding on ignition chemistries of the mixture under nanosecond discharge.
基金supported by Natural Science Foundation of Shannxi Province (No.2004F16)the On-the-job Doctoral Foundation of Xi'an Jiaotong University (for the year 2004)
文摘The effects of the Xe gas content and total gas pressure on the discharge characteristics of colour plasma display panels including the sustaining voltage margin, white-field chromaticity, discharge time lag （DTL）, discharge current peak, and full-width-at-half-maximum （FWHM） of the discharge current pulse, are experimentally studied. The results indicate that as the Xe gas content in the He-Ne-Xe gas mixture or total pressure increases, the sustaining voltage margin increases, the white-field chromaticity improves, and the discharge current peak has a maximum value, while DTL and FWHM have a minimum value. The mean electron energy in the gas mixture discharge is also calculated through a numerical solution of Boltzmann equation. The experimental results are explained from a view of the mean electron energy variations with the Xe gas content and total gas pressure.
文摘Low energy arc discharge characteristics was analyzed based on dynamic V-A characteristics model. It draws conclusions that discharge time relates to the source voltage and the product of inductance and stable current, discharge time will increase when the source voltage increases; current reduce rate is in inverse proportion to the value of inductance; arc resistance when the arc occurs is the ratio of minimum arcing voltage to stable current. It also gains the expressions of arc resistance and arc power, arc resistance and arc power both increase as the source voltage increases and decrease as the value of inductance increases. Conclusions above mentioned are helpful to design intrinsically safe circuits.
文摘BACKGROUND Laparoscopic nephrectomy is a preferred surgical approach due to its minimally invasive nature and faster recovery times.However,effective management of postoperative pain remains a significant challenge.Several traditional methods,including opioid-based analgesia,are commonly used but are associated with side effects such as nausea,vomiting,sedation,and delayed recovery.In recent years,the erector spinae plane block(ESPB)has gained attention as an ultrasoundguided regional anesthesia technique offering promising results in various surgical procedures by reducing opioid requirements and enhancing patient comfort.AIM To evaluate the efficacy and safety of ESPB in comparison to conventional pain management strategies in patients undergoing laparoscopic nephrectomy.METHODS Following PRISMA guidelines,we searched PubMed,EMBASE,Web of Science,and the Cochrane Register for randomized controlled trials(RCTs)comparing ESPB with control for laparoscopic nephrectomy.The Cochrane Risk of Bias tool was employed for quality assessment.The primary outcome was total patient-controlled analgesia(PCA)consumption.Secondary outcomes included hospital discharge time and the incidence of postoperative nausea and vomiting.A random-effects meta-analysis was conducted to calculate pooled mean differences(MD)and odds ratios(OR)with 95%CIs.RESULTS Nine RCTs involving a total of 643 patients(ESPB group=320;control group=323)were included in the analysis.ESPB significantly reduced PCA opioid consumption compared to controls(MD:-14.24,95%CI:-20.66 to-7.83,P<0.0001).Subgroup analysis showed reduced PCA use with ESPB vs morphine(MD:-8.78,95%CI:-15.34 to-2.22,P=0.009),and a non-significant effect compared to other analgesics(MD:-48.26,95%CI:-143.60 to 47.09).No statistically significant differences were observed in discharge time or the incidence of nausea and vomiting.CONCLUSION ESPB demonstrates the potential of reducing PCA in laparoscopic nephrectomy patients;however,its impact on secondary outcomes remains inconclusive.Large-scale RCTs are needed to confirm ESPB's benefits and explore long-term effects.
文摘Space ion electric propulsion has been widely used in the north-south position maintenance and orbit transfer missions for high-orbit satellites.However,unexpected electric breakdown by ion electric propulsion systems is still a challenging problem that needs to be solved,as it affects reliability.Based on the analysis of in-orbit and ground test data of ion thrusters from simulation and experimental results,the main influencing factors of induced electric breakdown are clarified and the mechanisms of induced electric breakdown are analyzed.It is found that the main factors inducing breakdown are the voltage and electric field strength between the grids.In addition,by monitoring the waveform of plasma discharge,the temporal characteristics of breakdown can be defined as three stages of“breakdown-spark-loop response”.Thus,three kinds of engineering suppression methods for breakdown of static vacuum with periodic short-term heating,electrode surface polishing and sealing insulation with plasma,add energy suppression circuit are carried out,and the experimental results show that the electric breakdown frequency can be reduced by about 30%.
基金Project 50274061 supported by the National Natural Science Foundation of Chinaprovided by the NSFC(50274061)+3 种基金the Program for Changjiang Scholars and Innovative Research Team in University(IRT0618)the Henan Province Basic and Lead-ing-edge Technology Research Program(082300463205 and 072300420180)the Program for New Century Excellent Talents in University of Henan Province(2005HANCET-05)the Henan Poly-technic University Innovation Funds of Graduate Student Scientific Dissertation(M-20)is gratefully acknowledged
文摘In order to apply ultra-fine water mist technology on spontaneous coal combustion in the goaf of a coal mine,we built a small scale compartment with ultra-fine water mist for restraining coal combustion in a confined space and then investigated the restraining efficiency and related factors.The study obtained the following results:a descending rate of heat release,an increase in O_(2),the production of CO_(2)decreased gradually,while the production of CO increased dramatically and quickly and then decreased;ultimately it tended to become stable after the discharge of an ultra-fine water mist.The technology showed that the ultra-fine water mist can effectively reduce the heat release rate of coal and the rate to generate components.We found that the restraining effect relied on the mist flux,the discharge time and other factors.A sufficient amount of mist has a better effect compared to an insufficient amount of mist.To combat coal combustion,the greater the discharge time,the better coal flames are extinguished.
基金supported by the New Century Talent Foundation of Ministry of Education of China (NCET-08-0438)
文摘Triggering characteristics of triggered vacuum switch （TVS）, including the discharge delay time, delay jitter, range of operational voltage and peak of pulsed current, are investigated. Both structure and experimental circuit of TVS are presented. The results indicate that TVS, as a surface flashover triggering device with high dielectric permittivity material, is with excellent triggering characteristics. When the hold-off voltage reaches 120 kV, the minimum operational voltage is 1.3 kV, and the minimum discharge delay time and jitter are 100 ns and ±10 ns, respectively. The peak current is up to 240 kA when the operational voltage reaches 100 kV. TVS can well satisfy the main demands of high voltage and current applications, and can also be used under a multi-crowbar circuit.
基金supported by the Major State Basic Research Development Program of China(Grant No.2010CB832902)the National Natural Science Foundation of China(Grant Nos.11275241,11275238,11105192,and 11375034)
文摘An analytical description for guiding of ions through nanocapillaries is given on the basis of previous work. The current entering into the capillary is assumed to be divided into a current fraction transmitted through the capillary, a current fraction flowing away via the capillary conductivity and a current fraction remaining within the capillary, which is responsible for its charge-up. The discharging current is assumed to be governed by the Frenkel–Poole process. At higher conductivities the analytical model shows a blocking of the ion transmission, which is in agreement with recent simulations.Also, it is shown that ion blocking observed in experiments is well reproduced by the analytical formula. Furthermore, the asymptotic fraction of transmitted ions is determined. Apart from the key controlling parameter(charge-to-energy ratio), the ratio of the capillary conductivity to the incident current is included in the model. Differences resulting from the nonlinear and linear limits of the Frenkel–Poole discharge are pointed out.
