Numerical Analysis of the Output-Pulse Shaping Capability of Linear Transformer Drivers

Output-pulse shaping capability of a linear transformer driver （LTD） module under different conditions is studied, by conducting the whole circuit model simulation by using the PSPICE code. Results indicate that a higher impedance profile of the internal transmission line would lead to a wider adjustment range for the output current rise time and a narrower adjustment range for the current peak. The number of cavities in series has a positive effect on the output- pulse shaping capability of LTD. Such an improvement in the output-pulse shaping capability can primarily be ascribed to the increment in the axial electric length of LTD. For a triggering time interval longer than the time taken by a pulse to propagate through the length of one cavity, the output parameters of LTD could be improved significantly. The present insulating capability of gas switches and other elements in the LTD cavities may only tolerate a slightly longer deviation in the triggering time interval. It is feasible for the LTD module to reduce the output current rise time, though it is not useful to improve the peak power effectively.

Influences of Switching Jitter on the Operational Performances of Linear Transformer Drivers-Based Drivers

A whole circuit model of a linear transformer drivers （LTD） module composed of 60 cavities in series was developed in the software PSPICE to study the influence of switching jitter on the operational performances of LTDs. In the model, each brick in each cavity is capable of operating with jitter in its switch. Additionally, the manner of triggering cables entering into cavities was considered. The performances of the LTD module operating with three typical cavity-triggering sequences were simulated and the simulation results indicate that switching jitter affects slightly the peak and starting time of the output current pulse. However, the enhancement in switching jitter would significantly lengthen the rise time of the output current pulse. Without considering other factors, a jitter lower than 10 ns may be necessary for the switches in the LTD module to provide output current parameters with an acceptable deviation.

Optical Diagnostics of Multi-Gap Gas Switches for Linear Transformer Drivers

The trigger characteristics of a multi-gap gas switch with double insulating layers,a square-groove electrode supporter and a UV pre-ionizing structure are investigated aided by a high sensitivity fiber-bundle array detector, a UV fiber detector, and a framing camera, in addition to standard electrical diagnostics. The fiber-bundle-array detector is used to track the turn-on sequence of each electrode gap at a timing precision of 0.6 ns. Each fiber bundle, including five fibers with different azimuth angles, aims at the whole emitting area of each electrode gap and is fed to a photomultiplier tube. The UV fiber detector with a spectrum response of 260-320 nm,including a fused-quartz fiber of 200 μm in diameter and a solar-blinded photomultiplier tube, is adopted to study the effect of UV pre-ionizing on trigger characteristics. The framing camera,with a capacity of 4 frames per shot and an exposure time of 5 ns, is employed to capture the evolution of channel arcs. Based on the turn-on light signal of each electrode gap, the breakdown delay is divided into statistical delay and formative delay. A decrease in both of them, a smaller switch jitter and more channel arcs are observed with lower gas pressure. An increase in trigger voltage can reduce the statistical delay and its jitter, while higher trigger voltage has a relatively small influence on the formative delay and the number of channel arcs. With the UV pre-ionizing structure at 0.24 MPa gas pressure and 60 kV trigger voltage, the statistical delay and its jitter can be reduced by 1.8 ns and 0.67 ns, while the formative delay and its jitter can only be reduced by 0.5 ns and 0.25 ns.

A Multi-Gap Multi-Channel Gas Switch for the Linear Transformer Driver

A multi-gap and multi-channel gas switch with convexo-convex discal planet electrodes was designed and investigated. Eight gaps are formed in series by a trigger electrode, six intermediate electrodes and two high voltage electrodes with a uniform gap length of 5 ram. The self breakdown and triggered breakdown performance of the switch are reported. Both the delay time and jitter decrease with the increase in the trigger voltage, switching coefficient and the decrease in the trigger isolating resistor. The delay time of the switch is about 40 ns, and the jitter is less than 2 ns when charged with 4-85 kV and triggered by a voltage pule of -75 kV. The inductance of the switch is about 30 nH.

Review of high-power pulsed systems at the Institute of High Current Electronics

In this paper,we give a review of some most powerful pulsed systems developed at the Institute of High Current Electronics(HCEI),Siberian Branch,Russian Academy of Sciences,and describe latest achievements of the teams dealing with these installations.Besides the presented high-power systems,HCEI performs numerous investigations using much less powerful generators.For instance,last year much attention was paying to the research and development of the intense low-energy(<200 kV)high-current electron and ion beam and plasma sources,and their application in the technology[1-3].

Z箍缩动力学行为及其直接驱动型脉冲源研究进展

Z箍缩在惯性约束聚变、强脉冲辐射效应等前沿科技和国家安全领域发挥着重要作用。该文综述了Z箍缩等离子体动力学行为及其直接驱动型脉冲源关键技术方面的研究进展。首先,总结Z箍缩等离子体的实验诊断技术的发展,特别是激光汤姆逊散射流场诊断方法以及基于磁旋光效应的磁场诊断方法;其次,分析Z箍缩消融、内爆等过程中磁场演化图像及其作用机理的研究进展;再次,面向提升内爆品质的需求,总结预脉冲电流调控质量分布、外施轴向磁场调控等对丝阵Z箍缩内爆动力学行为的影响。同时,面向功率百太瓦级的大型Z箍缩装置建设,概述直接驱动型脉冲源新技术路线中的快直线型变压器支路技术、触发技术以及单路脉冲源的主要进展。最后,总结并提出下一步需要重点攻克的研究方向,主要包括长内爆时间下等离子体不稳定性抑制方法、大型直接驱动型脉冲源电磁能高效传输汇聚方法以及可靠运行技术等。

西北核技术研究所强脉冲辐射模拟装置近年发展综述

西北核技术研究所是我国强脉冲辐射环境建设的主体单位,成立至今自主成功研制了一系列大型辐射模拟装置,形成了具有我国自主特色的辐射环境模拟体系和技术体系。近10年来,随着应用需求的持续拓展,西北核技术研究所在辐射模拟装置及其技术方面取得了新突破。本文重点介绍了西北核技术研究所近年新建成的大型强脉冲辐射模拟装置,包括大面积脉冲γ射线试验装置“云光一号”、4 MV脉冲X射线闪光照相装置“剑光二号”及强脉冲X射线试验装置等,分析了感应电压叠加、快脉冲直线变压器、多型射线负载等方面取得的最新技术进展,提出了未来强脉冲辐射模拟装置建设及其关键技术发展的初步设想。

支路开关自放电对大型多路并联FLTD脉冲源可靠性的影响

快脉冲直线型变压器驱动源(fast linear transformer driver,FLTD)是建设下一代大型Z箍缩装置最有前景的技术路线之一。大型FLTD脉冲源中数以万计气体开关的可靠运行是提高Z箍缩装置可靠性的重要因素。该文基于15 MAZ箍缩科学实验装置的FLTD脉冲源设计,采用Monte-Carlo方法建立考虑支路开关自放电及其载荷共享效应的FLTD脉冲源可靠性计算模型,分析开关故障模式及其触发策略对脉冲源可靠性的影响。结果表明,主支路开关自放电产生的故障电压会引起开关级联自放电,降低装置可靠性。若主支路开关工作系数设定在0.5~0.7范围内,FLTD脉冲源故障率可低于1×10^(-4)。此外,触发器及触发支路开关的高可靠性对于提升脉冲源可靠性至关重要,增加触发器脉冲数量、降低触发器自放电故障率能够有效提升脉冲源可靠性,当触发器脉冲数量提升至4倍后,FLTD脉冲源故障率有望降低至1×10^(-5)以下。研究结果为大型FLTD脉冲源的开关工作系数及触发策略的选取提供参考,具有重要的工程应用价值。

高频纳秒脉冲调制器的分立磁耦合驱动器设计

随着高压纳秒固态脉冲发生器在生物、工业和环境等领域的应用日益广泛和深入,脉冲波形、电压幅值、脉冲持续时间、脉冲重复频率等参数已成为特定脉冲功率应用所需的基本可控变量。为了进一步减小电源的体积、降低成本,提出一款以正极性Marx为主电路、多个脉冲变压器为核心驱动器、具有纳秒级前沿高重复频率的高压纳秒脉冲调制器。提出的驱动器结构紧凑,无需提供多路隔离供电的驱动电源,可以在高重复频率下实现两个金属氧化物半导体场效应晶体管(MOSFETs)的栅极电压快速同步上升和下降,获得百纳秒以内、幅值可控的栅极驱动电压。不仅最大脉宽不受磁芯饱和的限制,而且负偏置电压使开关管可控关断,同时在一定程度上避免了电流流过MOSFET米勒电容而引起的寄生导通,提高了电路工作的可靠性。此外,研究了不同匝数和磁芯材料对驱动波形的影响。搭建了一台14级脉冲调制器样机,测试结果表明,基于该驱动器下的调制器输出电压和脉宽都连续可调,具有改变脉冲轮廓的能力,最大输出电压可达5.5 kV,脉宽调节范围为100 ns~50 ms,最小上升时间约18 ns,重复频率为100 kHz。

直线变压器驱动源磁芯磁化过程的仿真研究

磁芯行为对于异常工况下直线变压器驱动源(linear transformer driver,LTD)的输出特性具有很大的影响,为了预测磁芯剩磁状况,为LTD装置调试和运行提供指导,基于磁芯的测试结果构建了准确的数值模型,并应用于LTD的电路仿真。基于4级串联共用腔体LTD数值仿真研究了开关理想时序放电、开关异常自放电、开关非理想时序触发放电及去磁状况下各级磁芯的磁场强度和磁感应强度变化过程。在±70 kV充电电压下的理想时序放电后,各级磁芯最大剩磁变化量为1.27 T,稳态剩磁约为-0.38 T;在±70 kV充电电压下的单支路开关自放电引起的磁芯最大剩磁变化量为1.88 T,稳态剩磁约0.39 T,多支路开关同时自放电将使磁芯快速饱和;当触发时序系数的绝对值>1时,除最先放电的模块,其余模块磁芯先受到反向励磁,然后再正常磁化;去磁过程中越靠近负载的磁芯越早被去磁,磁场强度随着各级磁芯依次去磁而呈现阶梯式上升。该研究结果能够有效地模拟各种工况下LTD磁芯的磁化过程与剩磁状态,判断当前磁芯剩磁对下一次放电脉冲的影响。

单路直线变压器驱动源中组件自放电连锁故障影响分析

建立电路模型分析了28级单路直线变压器驱动源(LTD)中可能出现的组件自放电连锁故障过程。结果表明当任何一个4级组件被误触发时,均会导致整个单路LTD连锁动作,产生的故障电压无法被单路驱动源输出端的隔离开关限制。且当误动的组件位于单路LTD下游时,电压沿着传输线向上游传播会在第1组件较低阻抗的传输线上产生远高于正常放电时的峰值场强,有可能引发装置的绝缘故障。通过适当增加第1组件传输线内外导体的间隙可以在几乎不影响负载电流输出幅值和波形的前提下削弱反向传播的连锁故障导致的高峰值场强,从而提高装置运行的可靠性。

小型脉冲功率发生器的电路方法与实践

基于实用的观点综述性地归纳了小型脉冲功率发生器的主要电路方法,从电路的储能原理和电压叠加到开关单元设计及控制信号的产生技术。以作者的实际工作内容为主,用具体的电路实例介绍了几种脉冲功率电路的基本结构和主要结果。这些电路包括:电容储能Marx发生器,电感储能Marx发生器,混合储能Marx发生器,电容储能直线型变压器驱动器(LTD)和电感储能LTD。

固态LTD的脉宽叠加技术仿真

针对脉冲电磁场生物医学应用中所需求的高电压大电流宽范围脉冲问题,文中采用脉冲叠加的方案设计了一种长脉宽固态直线型变压器驱动源(Linear Transformer Driver, LTD)。该LTD脉冲发生器为了突破脉冲变压器伏秒积限制下的脉宽范围,采用并联叠加的方式增加输出脉宽。设计了脉冲变压器的复位电路,提高了LTD输出脉冲占空比,能够实现最少支路LTD的多次脉冲叠加。通过Pspice搭建仿真电路模型进行仿真实验,结果表明在单匝脉冲变压器伏秒积为146 V·ms的情况下,实现单级电压为300 V,脉宽为1.6μs的脉冲输出,为其原伏秒积的3倍,且所提方案能够通过增加叠加脉冲个数来实现更宽范围的脉冲延长。

Investigation of convergent Richtmyer–Meshkov instability at tin/xenon interface with pulsed magnetic driven imploding

The Richtmyer–Meshkov instability at the interface of solid state tin material and xenon gases under cylinder geometry is studied in this paper. The experiments were conducted at FP-1 facility in Institute of Fluid Physics, China Academy of Engineering Physics(CAEP). The FP-1 facility is a pulsed power driver which could generate high amplitude magnetic field to drive metal liner imploding. Convergent shock wave was generated by impacting a magnetic-driven aluminium liner onto a inner mounted tin liner. The convergent evolution of the disturbance pre-machined onto the tin liner's inner surface was diagnosed by x-radiography. The spike amplitudes were derived from x-ray frames and were compared with linear theory.An analytical model containing material strength effect was derived and matched well to the experimental results. This sensibility of the disturbance evolution to material strength property shines light to the application of Richtmyer–Meshkov instability to infer material strength.

基于磁隔离驱动的双极性Marx脉冲源研制

该文针对脉冲功率技术在食品杀菌处理等领域的双极性高电压应用需求,设计了一种基于磁隔离驱动的全固态双极性Marx脉冲源。该双极性脉冲源主电路采用双Marx型电路拓扑。驱动电路采用磁心传递控制信号,利用磁心堆叠和次级绕组反并联方式,使得系统仅需两路驱动信号即可实现双Marx主电路拓扑中四种开关的控制。驱动电路结构简单可靠,开关同步性高。基于此驱动电路和主电路,筛选了主要器件,开展了相应仿真,最终研制出全固态双极性脉冲源样机,并开展了样机的性能测试。测试结果表明,该脉冲源输出电压为0~±20 kV,脉冲宽度为3~10μs,最大重复频率为200 Hz。脉冲源的输出电压、脉冲宽度、重复频率及正负脉冲间距均灵活可调,并可通过增加Marx模块的数量来实现更高等级的输出电压。

方波脉冲下高低剩磁非晶和纳米晶磁芯磁化特性

针对百纳秒量级方波直线型变压器驱动源(linear transformer driver,LTD)磁芯应用需求,建立了可调频方波脉冲产生电路,测量高、低剩磁非晶和纳米晶磁芯的磁化特性,获得不同等值频率下的磁滞回线,得到相对磁导率、磁感应强度增量及损耗等关键参数。研究结果表明,低剩磁非晶磁芯在高频下同样具有较高的矩形比,磁导率与同种材料的高剩磁磁芯相差较小,且相同频率条件下损耗更低;与非晶磁芯相比,相同频率条件下纳米晶磁芯最大相对磁导率大,磁芯损耗小。通过曲线拟合建立了损耗随频率的变化关系,可计算LTD在不同工作频率下的磁芯损耗。

A high efficiency and power factor, segmented linear constant current LED driver

A high efficiency, high power factor, and linear constant current LED driver based on adaptive seg- mented linear architecture is presented. When the input voltage varied, the proposed LED driver automatically switched over LED strings according to the segmented LED voltage drop, which increased the LED lighting time. The efficiency and power factor are improved, while the system design is simplified by this control scheme. Without the usage of electrolytic capacitor and magnetic components, the proposed driver possesses advantages of smaller size, longer lifetime and lower cost over others. The proposed driver is implemented in 0.8 μm 5 V/40 V HVCMOS process, which occupies an active area of 820× 920μm2. The measured results show that the average value of the internal reference voltage is 500 4- 7 mV, with a standard deviation of only 4.629 mV, thus LED current can be set accurately. Under 220 V root mean square 50 Hz utility voltage and the number ratio of the three LED strings being 47 ： 17 ： 16, the system can realize a high power factor of 0.974 and power conversion efficiency of 93.4%.

CMOS high linearity PA driver with an on-chip transformer for W-CDMA application

A fully integrated high linearity differential power amplifier driver with an on-chip transformer in a standard 0.13-μm CMOS process for W-CDMA application is presented.The transformer not only accomplishes output impedance matching,but also acts as a balun for converting differential signals to single-ended ones.Under a supply voltage of 3.3 V,the measured maximum power is larger than 17 dBm with a peak power efficiency of 21%.The output power at the 1-dB compression point and the power gain are 12.7 dBm and 13.2 dB,respectively. The die size is 0.91×1.12 mm;.

防爆高压脉冲电源研究进展

围绕高压脉冲技术在易燃易爆环境下的应用这一高压电器领域的热点问题,结合防爆要求和各类脉冲电源特点,选取性能参数优越、体积小、质量轻且发热量较少的固态开关串联脉冲电源、直线型变压器驱动源和固态Marx脉冲电源等3种固态开关式脉冲电源的研究进展进行了介绍。分析发现,固态开关串联脉冲电源结构紧凑、发热量较小,但输出电压幅值依赖于前级高压直流电源,且串联开关器件的同步和均压问题突出;直线型变压器驱动源降低了隔离要求,模块化设计可拓展性好,但防爆条件下进行拓展的价值不高,且采用大量变压器结构温升较另两种固态开关式脉冲电源较高;固态Marx脉冲电源在体积和发热量方面更具优势,同时具有效率高、响应快、波形调制灵活的优点,但存在高压隔离的难题。通过对现阶段各类高压脉冲产生方式的对比,在性能、发热量要求更为严格的防爆环境下,固态开关串联脉冲电源和固态Marx脉冲电源应用前景更好,为防爆高压脉冲电源的开发提供了参考。

快脉冲直线变压器驱动源模块的原理及实验

介绍了直线型变压器驱动源（LTD）产生快脉冲的基本原理及技术优势，阐述了快脉冲LTD模块设计的要点，设计了输出脉冲上升时间小于100ns的快脉冲LTD模块，并进行了初步的实验研究。实验得到该LTD模块充电士16kV时，短路放电的电流峰值为23．7kA，电流振荡1／4周期为69.6ns；充电±50kV驱动0．850负载时，电流峰值为41．4kA，上升时间为36．8ns（10％-90％）和60．8ns（0-100％）。