用于脉冲功率装置调试的高功率电阻分压器型负载

 介绍了电阻分压器型负载的结构、分压原理和设计方法,分析了高频作用下趋肤效应对负载阻值的影响,计算了负载和真空腔内的电场强度分布以及负载的等效电感和等效电容,利用Pspice程序模拟了回路参数对输出信号的影响。对负载的分压比进行了标定,标定结果为7.59×10^-5。为避免闪络现象的发生,设计加工接地金属套筒,用来降低负载阴极三结合点处的电场强度。负载工作电压幅值428 kV,电流幅值9.48 kA,工作阻抗45 Ω,电压和电流波形与设计值符合得较好,满足设计要求。     

Ultra-Wideband Wave Reactances of Capacitive Grids

The accuracy of transmission line models of two-dimensional freestanding capacitive grids is studied on a very wide frequency band. The grids are of infinite extent in the transverse directions and are illuminated by a linearly polarized normally incident plane wave. Comparison with reference results deduced from Finite-Difference Time-Domain (FDTD) simulations allows determining the range of validity of commonly used equivalent circuits It is shown that their accuracy strongly depends on the dimensions of the grids and the operating wavelength. Although very convenient, their implementation for calculating the frequency response of multi-layer systems could lead to unreliable results. Two closed-form new models are thus proposed. The first one results from an optimized expression of the well-known Marcuvitz's impedance, and the second one involves a series resonant LC circuit shunted by an additional capacitance. Both formulations are very accurate for a wide range of grid geometries and over the whole visible region (wavelength > grid constant).     

纳秒脉冲电压的波形重建

 介绍了一种根据脉冲电压测量系统的输入输出波形对纳秒脉冲电压信号测量系统进行参数计算的方法和技术，该方法基于最优化原理，并将其应用于快脉冲电压波形的重建。重建的波形用电容分压器实测波形进行了检验，表明重建波形有比用积分器更好的效果。     

二氧化锰纳米层的制备及电容性能研究

以Mn(NO3)2、Na OH和H2O2为原料,采用水热技术制备了Na型层状氧化锰(Na-Mn O2)。通过离子交换反应对NaMn O2进行了剥离,得到了氧化锰纳米层胶体分散液。将氧化锰纳米层分散液冷冻干燥后得到了氧化锰重组物(ERMn O2)。通过XRD、SEM和AFM对制备试样进行了分析表征。电化学测试结果表明,在1.0 mol·L-1Na2SO4水溶液中,当电流密度为0.25 A·g-1时,ERMn O2的质量比电容高达117 F·g-1远远高于其前驱物Na-Mn O2的比电容(79 F·g-1),并且表现出相似的循环稳定性。     

The Surge of Metal–Organic-Framework (MOFs)-Based Electrodes as Key Elements in Electrochemically Driven Processes for the Environment

Metal–organic-frameworks (MOFs) are emerging materials used in the environmental electrochemistry community for Faradaic and non-Faradaic water remediation technologies. It has been concluded that MOF-based materials show improvement in performance compared to traditional (non-)faradaic materials. In particular, this review outlines MOF synthesis and their application in the fields of electron- and photoelectron-Fenton degradation reactions, photoelectrocatalytic degradations, and capacitive deionization physical separations. This work overviews the main electrode materials used for the different environmental remediation processes, discusses the main performance enhancements achieved via the utilization of MOFs compared to traditional materials, and provides perspective and insights for the further development of the utilization of MOF-derived materials in electrified water treatment.     

Optimization of a Direct Sample Insertion Into a Stabilized Capacitive Plasma for Optical Emission Spectrometry (SCP-OES)

 A new sample insertion device for the stabilized capacitive plasma (SCP) has been developed, which enables it to analyze dry residues of micro amounts of liquid samples. Insertion was applied into an SCP as plasma source because of its good stability and excitation properties as well as its low instrument and operation costs. The plasma is sustained at a frequency of 27.12 MHz and an RF power of 150 W. For analysis the liquid samples are positioned at the tip of a quartz rod with the aid of a μL syringe. Then the sample is dried and the sampling rod inserted into the plasma. After optimization of the carrier gas flow (5 L/h) and the sample volume (20 μL) the detection limit for Pb with Ar as plasma gas is 200 pg. By further improving the guidance of the insertion detection limits for Pb, Cu, Cd and Mg in the 1 to 30 ng/mL range or 20 to 600 pg range absolute were obtained. It was found that the detection limits in the case of He are better than those obtained with Ar. The matrix interferences caused by changes in the concentration of the easily ionizable element Na were found to be below 10% for Na concentrations of up to 0.45 μg/mL. Ethanol concentrations of up to 14% in the analyte solutions did not cause any interferences. Received December 17, 1998. Revision June 4, 1999.     

磁绝缘传输线实验用电阻分压器型大功率负载设计

研制了一种用于磁绝缘传输线（MITL）实验的分压器型大功率水电阻负载,其阻值可在2.0~14.0 变化。利用MATLAB系统辨识工具箱和ANSYS电磁分析模块,分别获取了分压器的系统传递函数和沿面电场分布,给出了其幅频响应特性和沿面闪络可靠性分析,负载设计充分考虑了集肤效应和温升的影响。该负载已用于强光一号1.0 m长MITL特性研究实验,并获得了较好的测量波形,在负载阻值2.1 条件下,负载峰值电压为1.2 MV,峰值电流为494.4 kA,峰值时间约125 ns。将实验测量结果同TLCODE计算结果进行了对比,获得了较为一致的对比结果。     

不恢复余数法的等效变形—阵列除法器的数学分析(Ⅱ)

运算器对于CPU的性能有重要影响,除法器是运算器的一个重要组件.除法器电路常用不恢复余数法,但声称采用了不恢复余数法的各种电路采用的算法却有明显区别.及其前导文试图对不恢复余数法和不恢复余数阵列除法器电路进行分析.前导给出了不恢复余数法的一种初始形式,将给出初始形式的等效变形并展示阵列除法器电路是这种等效算法的硬件实现.     

微型化频率选择表面的设计研究

利用容性表面与感性表面之间的耦合机理能够制备微型化频率选择表面(MEFSS),周期单元尺寸将不受工作波长限制.为了提高MEFSS角度与极化的稳定性,展宽MEFSS的-3 dB带宽,文章结合传统频率选择表面"Y"形单元,利用"Y"图形构造容性表面的贴片单元与感性表面的网栅单元且以正三角形栅格拓展周期单元,采用矢量模匹配法对MEFSS栅格排布及其他结构参数变化进行精确计算.通过镀膜与光刻技术在0.15 mm厚聚酰亚胺膜两侧制备容性表面、感性表面并利用自由空间法测试.计算与实验结果均表明,采用正三角形栅格排布的MEFSS,-3 dB带宽达到7.6 GHz,不同极化下60°扫描时中心频点稳定在f₀,为MEFSS应用于曲面天线罩时提供理论与实验参考依据. 关键词： 天线罩 微型化频率选择表面 容性表面 感性表面