铌镁酸铋-钛酸铅压电陶瓷准同型相界附近的性能和相变温度研究

利用传统固相烧结法制备了Bi(Mg_2/3Nb_1/3)O₃-PbTiO₃(BMN-PT)压电陶瓷, 分析了不同PbTiO₃含量对BMN-PT压电陶瓷的晶体结构、介电、压电及铁电性能的影响. XRD结果表明: 合成的BMN-PT陶瓷具有纯钙钛矿结构, 并且在PbTiO₃含量为x=0.60时, 其组分的XRD图谱在衍射角2θ=45°出现明显的分峰, 说明该组分相结构中存在三方和四方相的共存. 压电铁电性能显示, BMN-0.60PT有最大的压电常数d₃₃(~170pC/N)和平面机电耦合系数k_p(0.35), 最小的矫顽场E_c(29.4 kV/cm)及最大的剩余极化P_r(31.4 μC/cm²). 确定了BMN-PT压电陶瓷的准同型相界(MPB)为PbTiO₃含量x=0.60的组分. 介电系数温谱表明介电系数峰值温度(Tm)随着PbTiO₃含量的增大而升高, MPB组分的Tm约为276℃.     

Optimization of Cavity Combination for 20 MA LTD-Based Accelerators

Based on a transmission line code,a circuit model is proposed that could serve as the basic method for the analysis of linear transformer driver (LTD)-based accelerators.By using 1MA,100kV LTD cavities,the peak load current is optimized for a total of N cavities between 500 and 1200.The simulation results suggest that,with the same number of cavities,the peak current changes obviously with the types of combinations,and the maximum change can be as large as 1.2MA.The results also show that,for the cases considered,the optimized peak current as a function of the total number of cavities agrees with the exponential associate,and the peak current for one level LTD cannot be enhanced infinitely.Furthermore,it is found that,to obtain a 20MA peak load current,at least 1029 LTD cavities (49 in series and 21 in parallel connection) are needed.Finally,the typical parameters of the optimized design are compared to those of the existing Z accelerator.     

Ultra Fast Shutter Driven by Pulsed High Current

Radiation simulation utilizing plasma radiation sources (PRS) generates a large number of undesirable debris, which may damage the expensive diagnosing detectors. An ultra fast shutter (UFS) driven by pulsed high current can erect a physical barrier to the slowly moving debris after allowing the passage of X-ray photons. The UFS consists of a pair of thin metal foils twisting the parallel axes in a Nylon cassette, compressed with an outer magnetic field, generated from a fast capacitor bank, discharging into a single turn loop. A typical capacitor bank is of 7.5 μF charging voltages varying from 30 kV to 45 kV, with corresponding currents of approximately 90kA to140 kA and discharging current periods of approximately 13.1 μs. A shutter closing time as fast as 38 microseconds has been obtained with an aluminium foil thickness of 100 micrometers and a cross-sectional area of 15 mm by 20 mm. The design, construction and the expressions of the valve-closing time of the UFS are presented along with the measured results of valve-closing velocities.     

无机、有机及其复合电介质的纳米尺寸效应及研究进展

当电介质内的不均匀区域达到纳米级时,纳米尺度效应对介电性能的影响便不容忽视。分别以PMN-PT弛豫铁电单晶、ZnO压敏陶瓷、纳米SiO2/环氧树脂复合材料为例,通过实验证明了在无机铁电单晶、半导体陶瓷以及无机纳米/有机复合材料中存在的介电性能的纳米尺寸效应。     

Influence of Cathode Materials on Opening Performance of Plasma Opening Switch

1.IntroductionTheplasmaopeningswitchhasbeenusedforpulsecompressionandpoweramplificationinavarietyofinductiveenergystoragesystemswithconduc-tiontimerangingfromtensofnanosecondstomorethanonemicrosecond.Significantprogresshasbeenachievedduringthelastdecadeintheunderstandingoftheoperationofaplasmaopeningswitch[l~7].Theinfluenceofelectrodesontheswitchperfor-mancehasbeeninvestigatedbyseveralresearcherswithmodifyingthecathodeshape,changingthean-odematerialordiameter,andcleaningtheelectrodesuslnggasdi…     

危化品生产装置区模拟泄漏训练塔应用

危化品生产装置区模拟泄漏训练塔对于提升基层消防人员训练水平,熟练掌握消防器材装备的应用技能,提高自身作战能力具有重要作用。针对经常遇到的危化品泄漏情况,模拟泄漏训练塔的设计突出了真实展现灾害现场的各种场景,其结构合理、功能齐全、安全可靠,确为消防战斗员正确使用消防堵漏器材和消防指挥员临场决策提供可靠的技战术训练保障。     

Simulation Analysis of Transmission-Line Impedance Transformers for Petawatt-Class Pulsed Power Accelerators

Based on the transmission line code TLCODE, a 1D circuit model for a transmission- line impedance transformer was developed and the simulation results were comp...     

电泳沉积法制备PNN-PZT厚膜的研究

利用电泳沉积法在φ50 μm的铂金丝上制备了厚度约50 μm的0.2Pb(Ni_1/3Nb_2/3)O₃-(0.8-x)PbTiO₃-xPbZrO₃ (PNN-PZT)致密压电陶瓷厚膜. 研究了不同聚合度的分散剂聚乙二醇(PEG)对悬浮液的Zeta电势和厚膜表面形貌的影响.结果显示, 加入高聚合度的分散剂PEG10000所制得的悬浮液比加入低聚合度的分散剂PEG6000制得的悬浮液更稳定, 并且电泳沉积得到的厚膜也更加致密. 本研究解释了不同聚合度的PEG对悬浮液稳定的可能原因, 并比较了连续电泳沉积法与分步电泳沉积法对厚膜表面形貌的影响, 结果表明采用分步电泳沉积法制备的厚膜更加致密. 研究了不同的烧结温度对PNN-PZT厚膜形貌和介电性能的影响, 结果显示烧结温度为1180℃时, 厚膜的介电性能最好, 介电常数达988, 介电损耗为3.7%. 测试了1180℃烧结的PNN-PZT厚膜的电压位移曲线和电滞回线, 结果表明厚膜的有效压电常数为90 pm/V,剩余极化为6.00 kV/cm.     

FLTD并联RLC网路型长脉冲功率源的概念设计

快直线型变压器(简称FLTD)是一种可直接获得脉宽100ns的高功率脉冲源,它在快Z箍缩、闪光照相、强激光和高功率微波等方面具有重要应用。为了更好利用和研究FLTD技术,提出了一种FLTD与RLC整形网络组合获得快前沿且具有平顶的长脉冲驱动源概念设想,给出了脉冲源的主要组成和电气参数。通过建立等效电路,模拟了主要电气参数和负载参数对输出波形的影响,电路模拟表明:该脉冲源在100Ω纯阻性负载上输出电压达700 kV,脉冲宽度(电压90%以上平顶宽度)>150 ns,电压脉冲上升沿约为20 ns。     

高功率Z-Pinch脉冲源技术的发展

概述了脉冲功率系统中的电容储能、电感储能和磁感应储能技术。基于直线型脉冲变压器（LTD）、电感储能（LES）、等离子体断路开关（POS）以及真空磁绝缘传输线（MITL）技术的低电感、模块化脉冲源将来可能作为基本的子模块应用于超大型高功率Z－Pinch装置。