Zinc Oxide Surface Flashover Triggering of Pseudospark Switch

Accurate and reliable triggering is one of the most important issues with high power pseudospark switch,because it not only has an impact on the design of discharge chamber of switch,but also has an influence on the dynamic range of operation voltage,repetition frequencies and lifetime of switch.The unique feature of pseudospark switch is its hollow cathode geometry.The hollow cathode effect produced by the hollow cathode provides the protection of the swithch for the triggering unit from erosion by high discharge plasma.In this paper,a zinc oxide(ZnO) surface flashover triggering is presented.This trigger unit possesses an excellent time delay(80ns-360ns) and jitter (20ns-50ns)at the switch voltage of 30kV-2kV.The emitted plasma electron density is high enough to trigger switch reliably down to switch voltage of 440V.     

A low-jitter self-triggered spark-discharge pre-ionization switch:primary research on its breakdown characteristics and working mechanisms

MV pulsed switch plays a key role as the transfer switch in large electromagnetic pulse simulators.To broaden the range of self-triggering time,a novel spark-discharge pre-ionization switch,in which the main gap electric field is superposed at the trigger gap to let the electrons in its spark channel also become initial electrons,is proposed and tested.The design idea is:as electrons in the spark channel of the trigger gap always exist after its breakdown,the injection time of pre-ionization should have a more negligible effect on reducing the switch jitter.The experiment results under pulses with a rise time of～100 ns support the above assumptions.When the operating voltage is from～300 to～800 kV and the self-triggering time is～45％to～75％of the peak time,the breakdown time delay jitter is less than 2 ns,and the breakdown voltage jitter is smaller than 1.25％.Under specific self-triggering time,the breakdown time delay jitter is less than 1.5 ns,and the breakdown voltage jitter is smaller than 0.8％.     

晶闸管强触发电路设计

为了研究晶闸管在强触发下的导通特性,利用功率MOSFET的快开通特性和通流能力,设计了光纤控制晶闸管强触发电路。该电路中晶闸管门极触发电流峰值范围为0.35～39.6 A,前沿范围为35～540 ns,电流上升率范围为3.4～83.3 A/μs。实验结果表明,该电路参数调节范围宽,触发电流抖动小(小于4 ns),具有较高的稳定性和可靠性。     

质子治疗装置脉冲电源研制

上海质子治疗装置项目中质子注入系统凸轨磁铁需要脉冲电源励磁,要求两台电源脉冲峰值幅度可调和波形一致,且运行可靠。本文介绍了凸轨磁铁脉冲电源的设计和测试。脉冲电源电路采用LC串联谐振作为脉冲成形发生电路,电路设计可调电感用于调整波形脉宽。晶闸管为电流开关,快恢复二极管串联晶闸管弥补大功率晶闸管的关断延迟和下冲,并增加饱和电抗器抑制励磁电流反向电流尖峰。测试结果表明,当励磁电流峰值为3 732 A时,励磁电流触发抖动小于±25 ns,励磁电流峰值重复稳定度小于0.1%,反向电流尖峰下降为峰值电流的3.75%,快恢复二极管和饱和电感器对抑制励磁电流反冲的效果明显,满足了设计要求。     

低抖动纳秒高压脉冲源研究

根据某高能物理实验要求,利用真空平面三极管驱动高压触发管,研制出脉冲幅度达10 kV、前沿小于3.5 ns、抖动低于1 ns,负载电阻R_L为50 Ω时峰值电流可达200 A的高压负脉冲源。本文介绍了该脉冲源的系统组成及工作原理,并给出了系统输出波形。     

双脉冲闸流管触发器研制

重氢闸流管开关在高压大电流快脉冲技术领域仍扮演着重要角色,闸流管的触发线路是决定闸流管开关性能的关键因素之一。除提高触发脉冲（G2）的幅度和上升速率外,采用双脉冲触发技术也可有效地改善闸流管开关的时间特性。从通用性、可靠性和可维护性的角度出发,研制了一种集成的全固态双脉冲闸流管触发器,并在BEPCⅡ运行中投入使用。通过测试,闸流管在该触发器的驱动下,时间抖动典型值<1 ns。3年多的运行实践表明,触发器的故障率极低,具有很高的可靠性。     

一种高精度低晃动可控延迟电路的设计和实现

介绍了一种可控延迟电路设计,具有精度高,晃动低,可调范围宽,低功耗的特点.延迟电路采用粗延迟和细延迟分别控制的方案,采用不同的粗延迟芯片可以达到不同的最大可调延迟范围,而细延迟的调节步长可以达到10 ps,整个电路的晃动小于100 ps,由此电路构成的延迟插件已成功地应用在量子密钥分发的实验中.     

中国散裂中子源快循环同步加速器束团长度研究

束团长度是中国散裂中子源（CSNS）快循环同步加速器（RCS）束流动力学的关键参数,通过对束团长度的研究,可了解RCS的机器性能并进一步指导机器优化研究。本文对RCS 100 kW时的束团长度进行精确测量,100 kW引出时的束团长度为105 ns。RCS 500 kW时束团长度可能超过无损引出允许值,需压缩束团长度。理论上提高腔压可压缩束团长度,本文模拟研究500 kW时束团长度随腔压曲线的变化规律,模拟结果表明提高加速后半阶段的腔压可压缩束团长度,给出了500 kW时无束流损失引出的腔压曲线。基于100 kW束流条件实验验证了通过提高加速后半阶段腔压来压缩束团长度的有效性和可行性,实验测量结果与模拟结果一致。因此,提高加速后半阶段腔压是500 kW时无损引出束流的有效方法。     

两个不同原理的延时功能NIM插件的研制

介绍了两套不同原理的延时功能NIM插件的设计。总延时量1μs的短延时插件采用它激同步时钟计数和可编程延时器件的设计方案,延时步长小于30ps,晃动小于50ps总延时量10ms的长延时插件采用基于FPGA,对外部100MHz的有源晶振计数的设计方案,延时步长10ns,晃动10ns。     

Comparative study on breakdown characteristics of trigger gap and overvoltage gap in a gas pressurized closing switch

Gas pressurized closing switches are one of the most important elements in FLTD-based systems. Improving the trigger performance of gas switches is useful for optimizing the output parameters and the reliability of the FLTD. In this paper, the breakdown characteristics of the trigger gap and the overvoltage gap are studied experimentally. The reasons for the different breakdown performance of the two gaps are also investigated. The results show that the breakdown delay of the trigger gap is more influenced by the trigger voltage, while the breakdown delay of the overvoltage gap is more influenced by the working coefficient and always higher than that of the trigger gap. The jitter of the trigger gap is more influenced by the trigger voltage and accounts more than 60% of the total switch jitter, while the jitter of the overvoltage gap is hardly changed with the trigger voltage as well as the working coefficient and maintains less than 1.4 ns. It is proved that the discharging product from the trigger gap can effectively reduce the breakdown delay and jitter of the overvoltage gap. Based on that, the effect and improvement of pre-ionization on the two gaps are also studied. It is concluded that the jitter of the trigger gap reduces obviously when the pre-ionization is added, while the pre-ionization almost has no effect on the jitter of the overvoltage gap. The jitter of the overvoltage gap is about two times higher than the trigger gap in the pre-ionizing switch.     

Design and Development of a Series Switch for High Voltage in RF Heating

Plasma is the fourth state of matter. To sustain plasma in its ionic form very high temperature is essential. RF heating systems are used to provide the required temperature. Arching phenomenon in these systems can cause enormous damage to the RF tube. Heavy current flows across the anode–cathode junction, which need to be suppressed in minimal time for its protection. Fast-switching circuit breakers are used to cut-off the load from the supply in cases of arching. The crowbar interrupts the connection between the high voltage power supply (HVPS) and the RF tube for a temporary period between which the series switch has to open. The crowbar shunts the current across the load but in the process leads to short circuiting the HVPS. Thus, to protect the load as well as the HVPS a series switch is necessary. This paper presents the design and development of high voltage Series Switch for the high power switching applications. Fiber optic based Optimum triggering scheme is designed and tested to restrict the time delay well within the stipulated limits. The design is well supported with the experimental results for the whole set-up along with the series switch at various voltage level before its approval for operation at 5.2 kV.     

Design of Capacitor Blocks with Multi-Channel Switches for Linear Transformer Driver Stages

In the linear transformer driver technology, the low inductance energy storage components and switches are directly incorporated into the individual cavities (named stages) to generate a fast output voltage pulse, which is added along a vacuum coaxial line like in an inductive voltage adder. In this paper, we outline the detailed design concept and the basic parameters of four capacitor blocks with four different types of multi-channel gas switches. The 100 kV capacitor block #1 and #2 incorporate two parallel capacitors (40 nF, 100 kV) and multi-gap multi-channel gas switches with triggering plate or triggering cable. The 200 kV capacitor block #3 and #4 incorporate two capacitors (40 nF, 100 kV) in series and rail-gap gas switches with one triggering rail or two triggering rails. Operating principles of four multi-channel gas switches are illustrated by using the equivalent electrical scheme of each switch. The basic characteristics of four capacitor blocks are given. The effect of stray capacitances on the trigger pulses is also discussed.     

Sub-ns Jitter, 1ns Risetime and 10kV Rectangular Pulse Trigger Generator

A new rectangular pulse trigger generator has been developed which can generate two 10 kV pulses with a risetime less than 1 ns, a jitter of 0.2 ns and a width of about 10 ns and 40 ns, respectively. This generator uses two polymer-foil switches and 25 ohm Blumlein transmission lines composed of two-parallel standard coaxial cables discharging into two 50 ohm output cables. The pulse width and the delay between two pulses can be adjusted by changing the length of the cables.     

100MHz程控时标脉冲产生器

本文介绍一种100MHz8通道程控时标脉冲产生器,它利用软件方法来改变各路时标对时间基准的延迟,调节灵活方便。最小时标宽度和最小延迟步长为10ns,时标延迟非线性和稳定性取决于输入高频时钟。     

多路高压电源带载测试仪

介绍了一种多路高压测试系统,并简要介绍了电路结构和电路设计、工作原理和技术指标。该仪器主要用于实验室和野外直流单路高压和多路高压系统电压值的测试,特别是对探测器偏压的测试。该仪器可以测量的额定电压最大值为6kV,电流值为0．1－10mA。仪器结构简单、集成度高、交直流供电、体积小、携带方便。     

混合模式低噪声3 kV高压直流电源设计

高压直流电源是电离室等核辐射探测器的关键部件。针对需要3 kV左右高压的电离室,本文研制了0～3 kV连续可调的低噪声、高效率、小体积及高稳定性的高压直流电源。该高压直流电源系统采用线性与开关混合模式设计,兼顾了转换效率与低噪声。核心部分升压转换部分采用线性罗耶谐振电路与高频变压器实现,保证足够低的高压电源输出纹波。罗耶谐振电路的供电电源则由边沿时间控制型超低噪声开关稳压器LT1534提供,从而实现了混合模式高压直流电源的设计。高压直流电源输出部分采用二阶RC滤波电路进一步降低了输出电压的纹波。实测输出电压范围为0～3 kV,静态功耗为0.4 W,3 kV输出时纹波为16.55 mV,由此可知该电源可用于低噪声的核辐射探测器供电场合。     

密封中子管氘-氘产额及二次电子抑制

中子管的工作参数是影响中子产额的重要因素.为了更准确地调控D-D中子管的中子产额,对中子管的工作参数与产额关系进行了研究,同时为了提高中子管束流品质及寿命,对中子管的二次电子抑制进行实验.采用控制参数变量的方法分别研究了D-D中子管的热子电流、阳极高压、靶极高压对中子产额的影响,以及二次电子抑制电阻阻值与靶极电流之间的...     

50kV,1ns前沿高压脉冲源的研制

介绍了50kV,1ns前沿高压脉冲源的工作原理及设计部件的研制,给出了脉冲高压源的输出波形,该高压脉冲源与有界波电磁脉冲模拟器辐照天线相接,可在其工作空间内产生前沿为1．2ns,脉宽为50ns的电磁环境,用于电子系统的电磁脉冲效应研究。     

High Voltage Series Switch and Crowbar Protection in RF Heating

Plasma is the fourth state of matter. High temperature is essential to sustain the plasma in ionic form. The RF heating system used to provide the required temperature may get damaged due to occurrence of arcing. Series switch (circuit breaker) is one of the most effective and efficient methods of protecting RF generators. The series switch must be operated within stipulated time after the occurrence of electric fault and therefore the triggering circuit of series switch must be designed carefully to obtain optimum results. This paper presents the designs of high voltage series switch and crowbar circuit developed for the protection of RF heating system. An optimum triggering scheme is designed to obtain the triggering with the delay of only 4.8 μS as compared to the safety margin of 10 μS. The importance of optical triggering and utilization of fiber optic has been justified. The designs are well supported with the experimental results.     

气体开关触发间隙与过压间隙击穿特性研究

为研究快脉冲直线变压器驱动源（FLTD）多间隙气体开关的触发击穿特性,针对一种环形电极两间隙等效实验开关,开展不同触发电压、工作系数和电极材料下的击穿特性实验,对比两个间隙的击穿延时和抖动,分析间隙击穿特性的主要影响因素和作用机制。实验结果表明：触发间隙击穿延时主要受触发电压影响,而工作系数是过压间隙击穿延时的主要影响因素;开关抖动主要来自于触发间隙,触发间隙抖动随触发电压的增大明显减小,过压间隙抖动基本不随触发电压和工作系数变化且维持在较低值;石墨电极开关的击穿延时和抖动明显小于不锈钢、黄铜和钨铜电极开关,具有良好的触发击穿性能。通过分析指出,是否有预电离可能是两个间隙击穿特性差异的主要原因。