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High-power microwave propagation properties in the argon plasma array
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作者 刘洋 时家明 +3 位作者 程立 汪家春 袁忠才 陈宗胜 《等离子体科学与技术:英文版》 SCIE EI CAS CSCD 2019年第1期44-51,共8页
The argon plasma induced by the L-/C-band high-power microwave(HPM) is investigated theoretically and experimentally. Influences of the microwave power, pulse width, polarization and the plasma electron density on the... The argon plasma induced by the L-/C-band high-power microwave(HPM) is investigated theoretically and experimentally. Influences of the microwave power, pulse width, polarization and the plasma electron density on the protection performance of the plasma array against HPM are studied. The results show that the effect of HPM is caused by energy accumulation, with the gas breakdown emerging only after a short time. The attenuation of the wave by the plasma array with the tubes off can reach approximately 23 dB at 1.3 GHz. It can also be obtained that the protection performance of the plasma array against the TE wave is better than that against the TM one. The plasma array shows better protection performance in the L-band than in the C-band. In addition,the attenuation of 5.6 GHz HPM can reach 30 dB when the tubes are turned on in the experiment.The research shows that the plasma array has protection ability against HPM. 展开更多
关键词 HIGH-POWER MICROWAVE plasma ARRAY ARGON BREAKDOWN protection performance EXPERIMENT
1780热连轧高压水蓄势器故障快速排除方法的应用 预览
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作者 周松涛 李珂 +1 位作者 梅林 王永广 《机械管理开发》 2019年第7期150-151,共2页
系统阐述了1780热连轧机组粗除鳞高压水系统的设备组成及功能,并对使用过程出现高压蓄势器漏水、漏气问题的快速排除方法进行分析和探讨,可以有效提升事故处理效率,降低损失,对同类事故的处理具有一定借鉴意义。
关键词 粗除鳞 蓄势器 故障 快速排除
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Detection of heavy metals in water samples by laser-induced breakdown spectroscopy combined with annular groove graphite flakes
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作者 方丽 赵南京 +5 位作者 马明俊 孟德硕 贾尧 黄行九 刘文清 刘建国 《等离子体科学与技术:英文版》 SCIE EI CAS CSCD 2019年第3期16-22,共7页
The use of laser-induced breakdown spectroscopy(LIBS)for the analysis of heavy metals in water samples is investigated.Some factors such as splashing,surface ripples,extinction of emitted intensity,and a shorter plasm... The use of laser-induced breakdown spectroscopy(LIBS)for the analysis of heavy metals in water samples is investigated.Some factors such as splashing,surface ripples,extinction of emitted intensity,and a shorter plasma lifetime will influence the results if the water sample is directly measured.In order to avoid these disadvantages and the‘coffee-ring effect’,hydrophilic graphite flakes with annular grooves were used for the first time to enrich and concentrate heavy metals in water samples before being analyzed by LIBS.The proposed method and procedure have been evaluated to concentrate and analyze cadmium,chromium,copper,nickel,lead,and zinc in a water sample.The correlation coefficients were all above 0.99.The detection limits of 0.029,0.087,0.012,0.083,0.125,and 0.049 mgl^-1 for Cd,Cr,Cu,Ni,Pb,and Zn,respectively,were obtained in samples prepared in a laboratory.With this structure,the heavy metals homogeneously distribute in the annular groove and the relative standard deviations are all below 6%.This method is very convenient and suitable for online in situ analysis of heavy metals. 展开更多
关键词 LASER-INDUCED BREAKDOWN spectroscopy quantitative analysis heavy metals GRAPHITE FLAKE
Time-resolved spectroscopy of femtosecond laser-induced Cu plasma with spark discharge
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作者 王秋云 陈安民 +5 位作者 徐万鹏 张丹 王莹 李苏宇 姜远飞 金明星 《等离子体科学与技术:英文版》 SCIE EI CAS CSCD 2019年第6期140-146,共7页
The combination of spark discharge and laser-induced breakdown spectroscopy (LIBS) is called spark discharge assisted LIBS.It works under laser-plasma triggered spark discharge mode,and shows its ability to enhance sp... The combination of spark discharge and laser-induced breakdown spectroscopy (LIBS) is called spark discharge assisted LIBS.It works under laser-plasma triggered spark discharge mode,and shows its ability to enhance spectral emission intensity.This work uses a femtosecond laser as the light souuce,since femtosecond laser has many advantages in laser-induced plasma compared with nanosecond laser,meanwhile,the study on femtosecond LIBS with spark discharge is rare.Time-resolved spectroscopy of spark discharge assisted femtosecond LIBS was investigated under different discharge voltages and laser energies.The results showed that the spectral intensity was significantly enhanced by using spark discharge compared with LIBS alone.And,the spectral emission intensity using spark discharge assisted LIBS increased with the increase in the laser energy.In addition,at low laser energy,there was an obvious delay on the discharge time compared with high laser energy,and the discharge time with positive voltage was different from that with negative voltage. 展开更多
关键词 LASER-INDUCED BREAKDOWN SPECTROSCOPY FEMTOSECOND laser spark DISCHARGE emission enhancement
Al丝物理状态调控及对芯晕演化特性的影响 预览
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作者 张金海 李沫 +6 位作者 孙铁平 王亮平 李阳 吴撼宇 丛培天 盛亮 邱爱慈 《原子能科学技术》 EI CAS CSCD 北大核心 2019年第12期2336-2343,共8页
基于快直线脉冲变压器(FLTD)平台开展了数十kA电流下Al单丝芯晕演化特性研究,实验发现丝过早发生电压击穿会减少丝芯的能量沉积,而晕等离子体的迅速发展将约束丝芯的进一步膨胀,降低丝芯膨胀速度。通过调整负载两端的初始电压、丝长及... 基于快直线脉冲变压器(FLTD)平台开展了数十kA电流下Al单丝芯晕演化特性研究,实验发现丝过早发生电压击穿会减少丝芯的能量沉积,而晕等离子体的迅速发展将约束丝芯的进一步膨胀,降低丝芯膨胀速度。通过调整负载两端的初始电压、丝长及增加闪络开关等手段,抑制了Al丝的过早击穿,增加了早期能量沉积,获得了不同的丝芯物理状态(部分气化或完全气化)。Al丝的气化提高了丝芯膨胀速度,最高达11~14 km/s,晕等离子体发展缓慢,延缓了边界处不稳定性的出现,降低了后期m=0的发展速度。FLTD负极性输出时,Al丝沿轴向的极性效应更加明显,靠近阴极处丝芯膨胀慢,边界处晕等离子体密度高,不稳定性的发展速度快。 展开更多
关键词 快直线脉冲变压器 芯晕 击穿 气化
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Signal processing for real-time identification of similar metals by laser-induced breakdown spectroscopy
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作者 Sungho SHIN Youngmin MOON +3 位作者 Jaepil LEE Hyemin JANG Euiseok HWANG Sungho JEONG 《等离子体科学与技术:英文版》 SCIE EI CAS CSCD 2019年第3期84-91,共8页
Laser-induced breakdown spectroscopy(LIBS)is regarded as a promising technique for real-time sorting of scrap metals due to its capability of fast multi-elemental and in-air analysis.This work reports a method for sig... Laser-induced breakdown spectroscopy(LIBS)is regarded as a promising technique for real-time sorting of scrap metals due to its capability of fast multi-elemental and in-air analysis.This work reports a method for signal processing which ensures high accuracy and high speed during similar metal sorting by LIBS.Similar metals such as aluminum alloys or stainless steel are characterized by nearly the same constituent elements with slight variations in elemental concentration depending on metal type.In the proposed method,the original data matrix is substantially reduced for fast processing by selecting new input variables(spectral lines)using the information for the constituent elements of similar metals.Specifically,principal component analysis(PCA)of full-spectra LIBS data was performed and then,based on the loading plots,the input variables of greater significance were selected in the order of higher weights for each constituent element.The results for the classification test with aluminum alloy,copper alloy,stainless steel and cast steel showed that the classification accuracy of the proposed method was nearly the same as that of full-spectra PCA,but the computation time was reduced by a factor of 20 or more.The results demonstrated that incorporating the information for constituent elements can significantly accelerate classification speed without loss of accuracy. 展开更多
关键词 LASER-INDUCED BREAKDOWN SPECTROSCOPY classification similar metal REDUCED number of SPECTRAL LINES
An efficient procedure in quantitative analysis using laser-induced breakdown spectroscopy
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作者 潘从元 何娇 +3 位作者 王广谦 杜学维 刘永斌 苏亚辉 《等离子体科学与技术:英文版》 SCIE EI CAS CSCD 2019年第3期92-97,共6页
Laser-induced breakdown spectroscopy has become a general-purpose technique,and internal standard calibration is a common method for quantitative analysis.Calibration models should be reconstructed for different syste... Laser-induced breakdown spectroscopy has become a general-purpose technique,and internal standard calibration is a common method for quantitative analysis.Calibration models should be reconstructed for different systems and application environments.This study presents an efficient procedure in the construction and selection of calibration models for LIBS analysis.The procedure concludes data preprocess,calibration model construction,and concentration calculation.These steps can be programmed without manual intervention.Results of the quantitative analysis of Ni-based alloys using the proposed procedure are presented in this study.Ten elements are calibrated,and most have an average relative standard error of less than 10%.The proposed procedure is an effective process for constructing and selecting calibration models. 展开更多
关键词 LASER-INDUCED BREAKDOWN SPECTROSCOPY QUANTITATIVE analysis PROCEDURE ALLOYS
10kV电动机轴瓦故障处理及分析 预览
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作者 安佩 《内燃机与配件》 2019年第18期168-169,共2页
球磨机作为氧化铝行业的主要设备,球磨机的运行状况直接关系到企业的生产稳定及效经济益.球磨机的工作任务主要是将铝土矿和循环母液进行混合,利用钢球进行研磨破碎,产出的原矿浆经过稀释后,送往溶出工序进行下一步的作业.而电动机作为... 球磨机作为氧化铝行业的主要设备,球磨机的运行状况直接关系到企业的生产稳定及效经济益.球磨机的工作任务主要是将铝土矿和循环母液进行混合,利用钢球进行研磨破碎,产出的原矿浆经过稀释后,送往溶出工序进行下一步的作业.而电动机作为球磨机的驱动部分,可以间接作为球磨机运行效率的体现,并且对实现氧化铝的稳定运行和连续作业打下基础. 展开更多
关键词 球磨机 轴瓦 油流继电器 击穿
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Passivity breakdown of 13Cr stainless steel under high chloride and CO2 environment 预览
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作者 Hui-xin Li Da-peng Li +3 位作者 Lei Zhang Ya-wen Wang Xiu-yun Wang Min-xu Lu 《矿物冶金与材料学报:英文版》 SCIE EI CAS CSCD 2019年第3期329-336,共8页
Herein, the effect of high chloride ion (Cl^-) concentration on the corrosion behavior and passive film breakdown of 13Cr martensitic stainless steel under CO2 environment was demonstrated. The Cl^- concentration was ... Herein, the effect of high chloride ion (Cl^-) concentration on the corrosion behavior and passive film breakdown of 13Cr martensitic stainless steel under CO2 environment was demonstrated. The Cl^- concentration was varied from 30 to 150 g/L and cyclic potentiodynamic polarization was conducted to investigate the influence of the Cl^- concentration on the corrosion potential (Ecorr), passive breakdown potential (Epit), and repassivation potential (Erep). The results of the polarization curves revealed that 13Cr stainless steel is susceptible to pitting under high Cl^- concentration. The passive breakdown potential and repassivation potential decreased with the increase of Cl^- concentration. The semiconducting behavior of the passive film was investigated by Mott-Schottky analysis and the point defect model (PDM). It was observed that the iron cation vacancies and oxygen vacancies were continuously generated by autocatalytic reactions and the higher Cl^- concentration resulted in higher vacancies in the passive film. Once the excess vacancies condensed at the metal/film interface, the passive film became locally detached from the metal, which led to the breakdown of the passive film. 展开更多
关键词 13Cr STAINLESS steel electrochemical characterization PITTING corrosion high CHLORIDE concentration PASSIVE film BREAKDOWN
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The influence of the metal microstructure on the breakdown mechanism of Schottky diodes 预览
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作者 Sh.G.Askerov M.G.Gasanov L.KAbdullayeva 《材料物理与化学》 2019年第1期57-62,共6页
In this paper, the influence of the microstructure of a metal on the breakdown mechanism of diodes with a Schott-ky barrier is studied. It is shown that in electronic processes occurring in the contact between a metal... In this paper, the influence of the microstructure of a metal on the breakdown mechanism of diodes with a Schott-ky barrier is studied. It is shown that in electronic processes occurring in the contact between a metal and a semicon- ductor, the metal plays a very active role and is a more important contact partner than a semiconductor. Unlike the known mechanisms of breakdown of diodes (avalanche, tunnel and thermal), another mechanism is proposed in this paper - the geometric mechanism of the reverse current flow of Schottky diodes made using a metal with a polycrystal- line structure. The polycrystallinity of a metal transforms a homogeneous contact into a complex system, which consists of parallel-connected multiple elementary contacts having different properties and parameters. 展开更多
关键词 SCHOTTKY DIODE Metal-semiconductor contact Interface BARRIER HEIGHT BREAKDOWN voltage
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Investigation of the factors affecting the limit of detection of laser-induced breakdown spectroscopy for surface inspection
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作者 Tadatake SATO Kenichi TASHIRO +2 位作者 Yoshizo KAWAGUCHI Hideki OHMURA Haruhisa AKIYAMA 《等离子体科学与技术:英文版》 SCIE EI CAS CSCD 2019年第3期174-181,共8页
Laser-induced breakdown spectroscopy(LIBS)was examined to detect a trace substance adhered onto Al alloys for the surface inspection of materials to be adhesively bonded.As an example of Si contamination,silicone oil ... Laser-induced breakdown spectroscopy(LIBS)was examined to detect a trace substance adhered onto Al alloys for the surface inspection of materials to be adhesively bonded.As an example of Si contamination,silicone oil was employed and sprayed onto substrates with a controlled surface concentration.LIBS measurements employing nanosecond UV pulses(λ=266 nm)and an off-axis emission collection system with different detecting heights were performed.Because surface contaminants are involved in the plasma formed by laser ablation of the substrates,the relative contribution of the surface contaminants and the substrates to the plasma emission could be changed depending on the conditions for plasma formation.The limit of detection(LOD)was evaluated under several detecting conditions for investigating the factors that affected the LOD.A significant factor was the standard deviation values of signal intensities obtained for the clean substrates.This value varied depending on the measurement conditions.For the Al alloy(A6061),the smallest LOD obtained was 0.529μg·cm^-2.Furthermore,an improved LOD(0.299μg·cm^-2)was obtained for the Al alloy with a lower Si content. 展开更多
关键词 LASER-INDUCED BREAKDOWN spectroscopy adhesive BONDING SURFACE CONTAMINATION detection pre-bond SURFACE inspection
汽车涂装工装夹具优化和管控
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作者 周少华 《现代涂料与涂装》 CAS 2019年第8期53-55,共3页
介绍了汽车涂装工装夹具的作用,探讨了涂装工装夹具的优化和管控方法,从而减少了工装夹具在生产使用过程中的故障,使得工装夹具能够长期安全可靠地为生产服务。
关键词 工装夹具 改善 管理 故障
运动微粒导致间隙击穿的模拟研究
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作者 徐翱 钟伟 +2 位作者 金大志 陈磊 谈效华 《真空科学与技术学报》 EI CAS CSCD 北大核心 2019年第8期637-643,共7页
当在充满气体的两电极平板间隙中,运动的带电微米级微粒由于外力作用运动到电极表面附近时,可能会引起微粒与电极间局部微放电,甚至在一定条件下可能会引发间隙气体击穿,这是一种非常特殊的击穿现象。因此,本文通过理论公式和静电场模拟... 当在充满气体的两电极平板间隙中,运动的带电微米级微粒由于外力作用运动到电极表面附近时,可能会引起微粒与电极间局部微放电,甚至在一定条件下可能会引发间隙气体击穿,这是一种非常特殊的击穿现象。因此,本文通过理论公式和静电场模拟,分析了不同大小的带电微粒距离阴极表面不同距离的电场畸变情况;接着基于二维轴对称网格粒子法耦合蒙特卡洛碰撞(PIC-MCC)算法,建立了带电微粒距离电极表面1μm处引发间隙气体击穿的仿真模型,并与不考虑微粒的仿真计算结果进行了对比,获得了电子、离子在不同情况下的时空分布演化过程,揭示了带电微粒接近导致阴极表面电场增强从而发射场致电子是引发间隙气体击穿的首要原因,并阐明了这些电子引发间隙击穿的物理机制。这为进一步深入理解运动微粒引发间隙击穿的物理机理奠定了基础。 展开更多
关键词 微粒 击穿 电荷 等离子体 模拟
收集极释气对相对论返波管影响的粒子模拟 预览
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作者 王洪广 柳鹏飞 +3 位作者 张建威 李永东 曹亦兵 孙钧 《物理学报》 SCIE EI CAS CSCD 北大核心 2019年第18期184-190,共7页
相对论返波管被认为是最具有应用潜力的高功率微波器件之一.随着输出微波功率的进一步提高,相对论返波管内部包括收集极处的击穿现象越来越严重,最终导致脉冲缩短,成为器件向高功率、高能量方向发展中的最大障碍,也是目前制约其发展的... 相对论返波管被认为是最具有应用潜力的高功率微波器件之一.随着输出微波功率的进一步提高,相对论返波管内部包括收集极处的击穿现象越来越严重,最终导致脉冲缩短,成为器件向高功率、高能量方向发展中的最大障碍,也是目前制约其发展的重要问题之一.本文基于自主研发的2.5 维粒子模拟软件UNIPIC-2D,采用动态释气模型研究了不同释气系数下相对论返波管收集极释气与电离过程及引导磁场的影响.粒子模拟结果表明,随着电子不断轰击收集极,收集极表面气压升高,并发生气体电离,产生的等离子体沿引导磁场进入慢波结构区域,影响束-波相互作用过程,使得输出功率下降;随着释气系数的增大,脉冲缩短现象越来越明显;在低引导磁场情况下,击穿以及脉冲缩短现象得到一定的缓解. 展开更多
关键词 相对论返波管 收集极 脉冲缩短 击穿
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A Brief Analysis of the Financial Crisis of 2008 预览
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作者 Haonan Yu 《商业经济研究(百图)》 2019年第4期22-24,共3页
The end of the first decade of the new century was a disaster for many people around the globe financially.The fall in the housing market in the summer of 2007 caused a series of chain reactions that would eventually ... The end of the first decade of the new century was a disaster for many people around the globe financially.The fall in the housing market in the summer of 2007 caused a series of chain reactions that would eventually cause a financial breakdown that led to the Great Recession in 2008.The causes of the Great Recession in 2008 was very complicated and hard to understand.But the basis of those causes was human greed that made people unaware of the real situation and over-optimistic about their capacity of handling the situation. 展开更多
关键词 FINANCIAL BREAKDOWN GREAT RECESSION FINANCIAL CRISIS
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基于数据挖掘的CVT电容元件击穿故障分析 预览
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作者 王俊波 李慧 邱太洪 《电力电容器与无功补偿》 北大核心 2019年第3期96-100,共5页
本文介绍了基于数据挖掘技术的电容式电压互感器(CVT)准实时在线监测系统构架,改系统中海量的 CVT 二次电压数据利用数据挖掘技术可以实现电容元件击穿的准实时监测,相比传统停电预防性试验更能够及时的发现潜在缺陷,在理论上对利用二... 本文介绍了基于数据挖掘技术的电容式电压互感器(CVT)准实时在线监测系统构架,改系统中海量的 CVT 二次电压数据利用数据挖掘技术可以实现电容元件击穿的准实时监测,相比传统停电预防性试验更能够及时的发现潜在缺陷,在理论上对利用二次电压变化用于 CVT 电容元件击穿故障判别进行了分析,并通过一起典型案例的剖析验证了该方法的有效性,最后对 CVT 绝缘监督提出了建议。 展开更多
关键词 CVT 数据挖掘 电容元件 击穿
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500 kV GIS绝缘拉杆击穿故障原因分析 预览
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作者 舒剑飞 陈骏星溆 +1 位作者 吕风仪 袁培 《湖南电力》 2019年第2期33-35,共3页
本文针对一起500 kV GIS操作过程中发生的绝缘拉杆击穿故障进行了详细分析。通过气体成分检查、解体检查、返厂试验等手段,指出了故障原因并给出了相应建议。
关键词 GIS 绝缘拉杆 击穿
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加速热老化对硅橡胶击穿及电荷输运特性的影响
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作者 严玉婷 吕启深 +1 位作者 陈铮铮 严智民 《绝缘材料》 CAS 北大核心 2019年第9期48-52,共5页
实际服役的220 kV高压电缆附件用硅橡胶材料在180℃下进行加速热老化,对老化后试样的交流击穿特性、表面电位衰减特性以及交联密度进行测试与分析。结果表明:随着热老化时间的增加,硅橡胶材料的击穿强度先增大后减小,在老化14 d时达到... 实际服役的220 kV高压电缆附件用硅橡胶材料在180℃下进行加速热老化,对老化后试样的交流击穿特性、表面电位衰减特性以及交联密度进行测试与分析。结果表明:随着热老化时间的增加,硅橡胶材料的击穿强度先增大后减小,在老化14 d时达到最大值。随着老化时间的增加,硅橡胶材料的电荷迁移率先减小后增大,在老化14 d时达到最小值。结合交联密度的测试结果分析认为,在老化初期,硅橡胶分子链段进一步交联,交联密度有所提升,硅橡胶对电荷的束缚能力增强,导致电荷迁移率减小,击穿强度增大。随着老化程度的加深,硅橡胶交联结构逐渐被破坏,交联密度减小,对电荷的束缚能力减弱,导致电荷迁移率增大,击穿强度减小。 展开更多
关键词 硅橡胶 热老化 击穿 迁移率 交联密度
Cumulative material damage from train of ultrafast infrared laser pulses
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作者 A.Hanuka K.P.Wootton +4 位作者 Z.Wu K.Soong I.V.Makasyuk R.J.England L.Schachter 《高功率激光科学与工程:英文版》 CAS CSCD 2019年第1期54-59,共6页
We developed a systematic experimental method to demonstrate that damage threshold fluence(DTF)for fused silica changes with the number of femtosecond laser(800 nm,65±5 fs,10 Hz and 600 Hz)pulses.Based on the exp... We developed a systematic experimental method to demonstrate that damage threshold fluence(DTF)for fused silica changes with the number of femtosecond laser(800 nm,65±5 fs,10 Hz and 600 Hz)pulses.Based on the experimental data,we were able to develop a model which indicates that the change in DTF varies with the number of shots logarithmically up to a critical value.Above this value,DTF approaches an asymptotic value.Both DTF for a single shot and the asymptotic value as well as the critical value where this happens,are extrinsic parameters dependent on the configuration(repetition rate,pressure and geometry near or at the surface).These measurements indicate that the power of this dependence is an intrinsic parameter independent of the configuration. 展开更多
关键词 LASER-INDUCED BREAKDOWN LASER damage lasers and LASER optics
Modeling electric field of power metal-oxide-semiconductor field-effect transistor with dielectric trench based on Schwarz–Christoffel transformation
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作者 汪志刚 廖涛 王亚南 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第5期366-373,共8页
A power metal-oxide-semiconductor field-effect transistor (MOSFET) with dielectric trench is investigated to enhance the reversed blocking capability.The dielectric trench with a low permittivity to reduce the electri... A power metal-oxide-semiconductor field-effect transistor (MOSFET) with dielectric trench is investigated to enhance the reversed blocking capability.The dielectric trench with a low permittivity to reduce the electric field at reversed blocking state has been studied.To analyze the electric field,the drift region is segmented into four regions,where the conformal mapping method based on Schwarz–Christoffel transformation has been applied.According to the analysis,the improvement in the electric field for using the low permittivity trench is mainly due to the two electric field peaks generated in the drift region around this dielectric trench.The analytical results of the electric field and the potential models are in good agreement with the simulation results. 展开更多
关键词 CONFORMAL mapping Schwarz–Christoffel TRANSFORMATION electric field TRENCH metal-oxidesemiconductor FIELD-EFFECT transistor (MOSFET) breakdown voltage
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