Microchamber setup characterization for nanosecond pulsed electric field exposure

Intracellular structures of biological cells can be disturbed by exposure to nanosecond pulsed electric field (nsPEF). A microchamber-based delivery system mounted on a microscope setup for real-time exposure to nsPEF is studied in this paper. A numerical and experimental characterization of the delivery system is performed both in frequency and time domains. The microchamber delivery system presents a high impedance compared to classical 50 Ω loads. Its frequency behavior and limits are investigated using an in-house finite-difference time-domain (FDTD) simulator and through experimental measurements. High-voltage measurements for two nsPEF generators are carried out. The applied pulse voltage measured across the microchamber electrodes is ～1 kV, corresponding to ～10 MV/m electric fields in the microchamber. Depending on the nsPEF generator used, the measured pulse durations are equal to 3.0 and 4.2 ns, respectively. The voltage distribution provided by FDTD simulations indicates a good level of homogeneity across the microchamber electrodes. Experimental results include permeabilization of biological cells exposed to 3.0-ns, 10-MV/m PEFs.     

纳秒脉冲半导体激光驱动器的研究

为了获得高功率、高重复频率的纳秒级光脉冲,介绍了一种基于Marx bank脉冲发生原理的纳秒脉冲激光驱动器的设计,以及设计过程中雪崩晶体管的选取.该驱动器采用一级小雪崩管对触发脉冲进行陡化,由小雪崩管产生的脉冲对Marx bank电路进行触发,以获得大电流窄脉冲,用于驱动半导体激光器.设计所得驱动器的峰值电流为12.5A、半峰全宽为1.51ns、重复频率为100kHz,实现了大幅度纳秒脉冲半导体激光驱动器的设计要求.结果表明,对触发脉冲的陡化,可以降低后一级Marx bank电路的雪崩电压,同时使得脉宽更窄,这将更加有利于驱动半导体激光器.     

强脉冲电场测量技术研究

强脉冲电场测量技术在强流加速器系统电磁兼容设计、核电磁脉冲（NEMP）测量、雷电电磁脉冲（LEMP）效应研究以及高压输电线、大功率开关的电磁辐射澳0量中起着关键的作用,测量结果的有效性直接影响到理论研究和系统设计的正确性。本文系统地回顾了强脉冲电场测量技术的发展,对有源电光调制法和基于Pockels效应的无源电光调制法两种常用方法进行了详细的分析比较,说明测量系统的研究正朝着提高稳定性、探头微小化、探头无源化、提高带宽、提升灵敏度、后端信号处理便捷、系统维护方便、容易实施标准化测量等方向发展;文章还对测量实践中的屏蔽、信号区分以及获取特征量等具体方法和技巧作了研究,为强脉冲电场的准确测量打下基础。     

Potential distribution for a spheroidal cell having a conductivemembrane in an electric field

When a cell is situated in a uniform electric field, the field is modified due to the relatively low conductance of the cell membrane compared to that of the surrounding fluids. In certain cases, such as in the estimation of internal and external electrokinetic forces, one requires a means of estimating the magnitude of the electric field inside and outside the cell. Most treatments consider the case when the membrane has zero conductivity, or the case of only a spherical cell. The authors solve Laplace's equation for the electric potential distribution inside and outside a cell having a prolate spheroidal shape and having a membrane with a finite, nonzero conductivity     

Energy yield of pulsed optical parametric oscillators: a rate-equation analysis

In this paper, for the first time, to our best knowledge, single explicit self-contained rate equations describing the dynamic behavior of pulsed optical parametric oscillators are derived, exactly taking into account the parametric interactions between the three waves in the nonlinear crystal, in contrast to most previous approaches which used a linearized expansion of this interaction. Universal expressions using normalized forms are derived which fully include pump depletion and reconstruction effects. Straightforward numerical integration of these equations allow us to study the input energy-output energy characteristics of these pulsed devices. We thus discuss the subthreshold behavior, threshold power, saturation, and build-up time of optical parametric oscillators and find the validity range in which the usual undepleted regime is retrieved as a limit case of the general expressions. Explicit approximated expressions of build-up times are derived which show in particular that the number of round trips needed to reach a CW behavior may be very large.     

Metal cathode patterning for OLED by nanosecond pulsed laser ablation

Throughthe efforts of researchers for about two dec-ades since Tang invented organic light-emitting diode(OLED) in 1987[1],OLEDs are coming into practicalapplications as the displayfor some niche products ,suchas mobile phone,mp3 and etc .To make a matrix…     

Implementation and parametric analysis of single and dual band planar filtering antennas for WLAN applications

Wireless Networks - Implementation and parametric analysis of single and dual band planar filtering antennas suitable for WLAN applications are described in this paper. The single band filtering...     

基于高压脉冲电场技术的污水处理系统研究设计

针对污水处理厂剩余污泥含水率高,达到70%~80%,不利于进一步处理的问题,根据污水成分及其处理工艺特点,提出了一种基于高压脉冲电场技术的污水处理的方法。本文从理论上系统地阐述了高压脉冲电场处理装置的研制,设计了低成本高压脉冲电源,最高电压10 kV,最大电流50 A,并且能方便的调节电场参数。     

The effect of a strong electric field on the conductivity of a MnGaInS4: Eu single crystal

This paper presents the results of a study of the effect of a strong electric field on the electrical properties of MnGaInS₄: Eu single crystals. The compound was obtained by the Bridgman method and consists of plane-parallel layered plates. The following parameters are determined on the basis of these studies: concentration of trap levels 10¹³–10¹⁴ cm⁻³ and activation energy 0.70–0.50 eV. It is established that the conductivity of MnGaInS₄: Eu increases in strong electric fields mainly because the current-carrier concentration increases with electric field. Fiz. Tekh. Poluprovodn. 32, 701–702 (June 1998)     

Electron holography study of electric field variations

This paper presents a review of the recent electron holography studies on electric field variation that have been carried out using multifunctional specimen holders. In addition to the standard inner potential analysis, studies on electric field variations around field emission tips have been carried out. The electric field variations caused by ballistic emission in the case of a field emitter made of a TaSi(2) nanowire have been analyzed using electron holography. The charges and electric fields in electrophotographic materials such as toner particles and organic photoconductors have been quantitatively evaluated after equipping the specimen holder with a piezodriving probe to shield the specimens from electron irradiation. The conductivity and electric field variations in the case of Ag-based conductive adhesives have been analyzed by applying an electric current through the holder. Finally, the characteristic charging effect induced by electron irradiation in biological specimens has been studied. It has also been pointed out that under certain experimental conditions, the stationary orbits of electron-induced secondary electrons can be located by electric field visualization.     

An InP-based optothyristor for pulsed power-switching applications

A high-power InP-based optothyristor has been fabricated and tested for pulsed power switching. To increase the power handling capability, the device has a 250 μm-thick Fe-doped semi-insulating (SI) InP sandwiched between two p-n junctions grown by MOCVD. The device turn-on is controlled by optical illumination on the SI-InP, which creates a high concentration of electron and hole pairs. The switched current and the di/dt rating have been studied as a function of the switch blocking voltage. It is shown that the optothyristor is capable of switching a current almost four times the current switched by a bulk SI-InP photoconductive switch under the same voltage bias     

A deep parametric study of resistor-loaded bow-tie antennas for ground-penetrating radar applications using FDTD

Resistor-loaded bow-tie antennas are analyzed thoroughly to find out their performance on ground-penetrating radar (GPR) applications. The analysis is done with the finite-difference time-domain (FDTD) technique. The antenna is pulse driven and enclosed in a rectangular conducting cavity. The ability to detect a buried conducting sheet using two such identical antennas for transmitting and receiving is investigated. Simulations are carried out for various antenna parameters like end resistor values, flare angle, and antenna length. The gap between the two antennas and their height above the ground are also varied. Moreover, the results are obtained for different sizes, depths, and positions of the buried sheet. It is studied how the broadband impedance characteristics and better target discrimination with low clutter can be achieved by optimally selecting these antenna parameters. Also, it is shown that apart from the total parallel end resistance, the individual end resistor values and the number of resistors connected have no significant effect on the input impedance and the received signal.     

自发参量下转换光场的实验研究进展综述

自发参量下转换(spontaneous parametric down-conversion,SPDC)光场是基于单色泵浦光子流和量子真空噪声对非线性晶体的综合作用而产生的,它固有的量子起源决定了在非经典光场研究中的重要地位和作用.对SPDC光场的相干特性和它在绝对测量光电探测器量子效率中的应用进行了深入而细致的研究和探讨.     

Properties of a pulsed LiIO3doubly resonant parametric oscillator

Spectral and other properties of a ruby laser pumped LiIO3pulsed doubly resonant parametric oscillator (DRO) are reported. This device is tunable from 1.12 to 1.83 μ with peak powers of 100 kW and 10-percent efficiency. The stability of the DRO is discussed. The output of the DRO was doubled into the 5600- 9150-Å range using a second LiIO3crystal. Peak second-harmonic powers were 10-15 kW.     

A submillimeter gyrotron with a pulsed magnetic field

Pulse solenoids seem promising for sumbillimeter wave generation in gyrotrons. In this paper a single-pulse submillimeter gyrotron with a pulsed magnetic field is described. At the wavelength 0.8 mm the output power 120 KW with the efficiency 15% has been obtained.     

Translational rotational motion compensation: a single algorithm for different radar maging applications

A single algorithm for various radar imaging applications is presented. The idea behind the proposed approach is that any motion between radar and target can always be modelled as a composition of translational and rotational components. Novel techniques to estimate and compensate these two motion components are discussed and also validated by application to real radar data for different targets (ships, aircraft, ground). By the translational-rotational-motion-compensation algorithm, good results can be achieved, especially in cases characterised by evident variation of the rotation rate during the coherent processing time for imaging. This usually happens in aircraft, ship or ground mover inverse synthetic aperture radar (ISAR) imaging as well as in squinted or for.ward-looking SAR. In any case, the efficiency and the accuracy of the algorithm presented for translational motion compensation might be the initial step of alternative radar imaging processing. The simplicity of the proposed algorithms makes them suitable and convenient for real-time application even for compact and low-weight radar systems to be fitted on board unmanned aerial vehicles (UAV) or other airborne platforms. The proposed concept is the result of the authors' decennial experience devoted to achieve a single, simple, robust, reliable and efficient signal processing algorithm for several real-time radar imaging applications.     

加载横电磁传输室中的电场分布计算

用“准静脉法”研究了当工作频率远低于截止频率时,放置于横电磁传输室中的被测物体中的电场分布。文中使用的是有限差分法,给出了在三维空间中不同介质交界面上拉普拉斯方程的差分格式。计算结果表明当把ＥＴＵ放入ＴＥＭＣｅｌｌ的中心时,ＥＵＴ横截面上的电场分布是均匀的。     

A model study of electric field interactions between cardiacmyocytes

The transmission of excitation via electric field coupling was studied in a model comprising two myocytes abutted end-to-end and placed in an unbounded volume conductor. Each myocyte was modeled as a small cylinder of membrane (10 microns in diameter and 100 microns in length) capped at both ends. A Beeler-Reuter model modified for the Na+ current dynamics served to simulate the membrane ionic current. There was no resistive coupling between the myocytes and the intercellular junction consisted of closely apposed pre- and post-junctional membranes, separated by a uniform cleft distance. The membrane current crossing the prejunctional membrane during the action potential upstroke tends to flow out of the cleft, but it is partly prevented from doing so by the shunt resistance constituted by the cleft volume conductor. The prejunctional upstroke gives rise to a pulse of positive potential within the cleft which induces a small capacitive current across the post-junctional membrane to yield a small positive change in the intracellular potential in the post-junctional cell. The net result is an hyperpolarization of the post-junctional cleft membrane and a slight depolarization of the rest of the cell membrane since the extracellular potential outside of the cell is zero. The magnitude of this depolarization is quite small for a flat junctional membrane and it can be increased by membrane folding and interdigitation, so as to increase the junctional membrane area by a factor of 10 or more. Even then the post-junctional depolarization does not reach threshold when the extracellular potential around the post-junctional cell is effectively zero. Threshold depolarization occurs in the presence of a large decrease of post-junctional load, by increasing the junctional membrane capacitance and/or decreasing the volume of the post-junctional cell. Assuming that the normal resistive coupling between two cardiac myocytes is 1-4 M omega, our model study indicates that electric field coupling would then be about two orders of magnitude smaller. However, substantial enhancement of the efficacy of electric field transmission was observed in the case of cells with substantial junctional membrane folding.