脉冲中子发生器高压控制系统的自动控制设计

针对在研制脉冲中子全谱测井仪过程中传统高控系统难以对不同测井模式产生多种阳极控制时序,难以达到阳极高压、灯丝供电、靶压三者的有序的控制使中子产额稳定的要求。设计本脉冲中子发生器自动控制系统能够实现阳极高压双爆发时序,能在非弹模式下兼测得Σ及活化谱;本系统还能实现中子发生器多种状态的实时测量,靶压的PWM控制,灯丝电流的自动控制使中子产额稳定达到脉冲中子全谱稳定测量的目的。     

中子管脉冲中子束调制

随着科学技术的发展,中子管的应用日益增多。在应用中,有时需要脉冲中子束。有两种方法能获得脉冲中子束。一种是把中子管的加速高压脉冲化,这种方法因为有输送脉冲加速高压的问题,所以很少用。另一种是把离子源脉冲化,这种方法较简单,也较常用。为了给缓发中子测铀井模拟试验提供宽度为100毫秒量级的脉冲中子束,我们利用离子源脉冲化方法制作了一台中子管脉冲中子束调制装置。经过几年的运用表明,性能稳定     

基于PLC控制的200kV高压脉冲发生器

针对真空器件的老化锻炼需要,设计了基于PLC控制的正负200 k V高压脉冲发生器装置。系统采用工业PLC和工控计算机结合的方式,实现对直流高压充电电源的数字控制、氢闸流管触发脉冲的时间控制、极性转换高压继电器的转换控制、限流电阻的调节控制。利用高性能示波器的数据获取功能,通过USB接口实时获取高压脉冲的电压、电流、波形及时间信息,基于WINCC V6.2设计了良好的人机交互界面,实现了真空器件击穿的智能判断和检测,也可以在自动状态下实现器件的各种流程的老化锻炼。系统采用PLC控制,使其在大脉冲放电的恶劣环境下能可靠长期稳定地工作。     

脉冲中子测井仪综合时序发生器设计

研制了一种适用于脉冲中子测井仪的井下全谱采集控制综合时序发生器和阳极高压变换器。该时序发生器可通过阳极高压变换器产生碳氧比、中子寿命、能谱水流、脉冲中子氧活化等测井方法的中子爆发时序,并控制多种测井方式的信号采集。以综合时序发生器为电路核心的井下双路多道谱仪采用MPU+CPLD优化技术设计，阳极高压变换器实现了模块化。将采用上述技术设计的小直径脉冲中子综合测井仪应用于实际测井，现场测试结果表明，仪器的重复性良好，稳定可靠     

用嵌入式系统实现中子厅的监测

中子厅内较强的辐射限制了对中子管老炼等实验过程的实时操作与检测.针对中子厅的测量要求,设计了一套操作简便、扩展性强的远程监测系统.该系统的硬件以S3C2410处理器为核心,实现包括中子计数、图象信息采集、环境检测以及网络通信等功能.     

电桥应力系统在强脉冲中子场中的辐照效应

以快中子脉冲反应堆为试验平台,简要描述了电桥应力系统在强脉冲中子辐射场中的辐照效应表象,以效应试验结果为基础,分析了辐照效应产生机理,并据此提出了减小或消除辐照效应的基本方法.验证试验结果表明:精密桥臂电阻的瞬态中子辐射损伤是导致应变信号出现突变的根本原因,而采用辐射屏蔽和"背片法"的措施可以有效地减小或消除应力系统的辐照效应.     

DPF装置脉冲中子测量技术研究

研制了用于DPF装置脉冲中子产额和波形监测的脉冲中子飞行时间-闪烁探测系统。在中国原子能科学研究院高压倍加器上采用电流法和脉冲中子飞行时间方法标定了该系统的D-T和D-D中子灵敏度。根据测量的光响应函数,采用Monte-Carlo方法模拟了塑料闪烁探测器的中子能量响应,由此对中子灵敏度标定结果进行了能量响应修正。利用研制的闪烁探测系统对ING-103型DPF装置的D-T脉冲中子产额和时间波形进行了实验测量,并对测量结果进行了分析和讨论。测量的DPF装置D-T脉冲中子产额在1×109–2×109n/shot之间,中子时间波形的半高宽约为9ns。     

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...     

CMOS器件SEL效应电路级防护设计及试验验证

利用脉冲激光单粒子效应试验装置,开展了两种CMOS SRAM器件IDT71V416S和K6R4016V1D单粒子闭锁(SEL)效应的研究。基于CMOS电路结构SEL效应的机理及触发条件,分析两种CMOS器件的闩锁响应特性,设计了两种CMOS器件SEL效应防护电路,并探讨了两种防护电路的适用范围及限流电阻、恒流源电流的选取。利用脉冲激光和重离子辐照试验验证了两种防护方法的防护效果。结果表明,当器件工作电流和闩锁维持电流相差不大时,加入限流电阻虽能降低闩锁电流幅值,但电路不能自动退出闩锁状态。恒流源限流防护电路不但降低了SEL电流的幅值,而且自动退出闩锁状态,能更有效地减缓CMOS器件电路级闩锁效应。     

BF_3计数管的电荷积累效应和辐照效应

一、引言浓缩硼BF_3正比计数管是常用的中子探测器,一般在低中子通量和低γ场中使用,长期工作性能比较稳定,是一种良好的中子探测器。在缓发中子测井装置中,BF_3计数管的高压处于调制状态,脉冲中子束辐照时,BF_3计数管的高     

SRAM单粒子锁定效应电路级防护设计研究

高密度CMOS工艺SRAM对单粒子锁定极端敏感的特性使其在空间应用时必须采取相应的防护策略。对于抗辐照能力较弱的CTOS,电路级防护成为提高系统可靠性的一项重要内容。利用激光单粒子效应试验装置,对CYPRESS公司的CY62167DV30LL型SRAM开展了一系列单粒子锁定效应试验。通过对试验结果进行线性拟合,计算出该款SRAM维持电压为1?5?1?6 V,维持电流为9?9?11?2 mA。根据维持电流、维持电压、工作电流、工作电压,对能否采用电路级防护做出判断。提出了电源限流和分压电阻两种电路级防护方法,并定量计算出电源限流取值和分压电阻取值范围。以往文献中电阻只是作为锁定被触发后限流的一种手段,并不能阻止器件发生锁定,本研究发现在满足一定条件下分压电阻可达到退出锁定的目的。两种防护方法均通过脉冲激光试验进行了验证。     

Analysis and optimization of high-power pulse transformer for SXFEL

A C-band accelerator structure was used to accelerate electrons at the Shanghai soft X-ray free-electron laser test facility(SXFEL-TF) in Shanghai Institute of Applied Physics(SINAP). The microwave system of this accelerator structure used a 110 MW pulse modulator and a klystron(PV-5050) to provide the power supply. A pulse transformer is a crucial device in a modulator klystron system and plays significant roles in voltage level transformation, matching impedances, and polarity inversion.This study presents the optimization of a high-voltage pulse transformer. The design considerations of reducingflattop ringing and flattop droop, and shortening leading edge are provided. The model simulation, mechanical design, and the relevant experimental results are also presented.     

Design and Performance of a Compact Marx Generator for Two-Electrode Gas Switch Used in ICF Power Conditioning System

As the high-current, high-coulomb transfer two-electrode graphite gas switch had no trigger electrode and must be triggered by a nanosecond pulse, a compact Marx generator was developed to produce a nanosecond rise-time, voltage level around 100 kV negative pulse to trigger the gas switch. This paper presented the structure of the compact Marx generator and the performance used in ICF power conditioning system. The effect of the ultraviolet radiation was utilized to decrease the amplitude of the breakdown voltage of the spark gaps. Coaxial structure of the metal shell was employed to reduce the inductance of the Marx generator. Additional isolation circuits were improved to prevent the electromagnetic disturbance which was significant for the application of the two-electrode graphite gas switch. The results showed that the designed compact Marx generator was suitable and have been successfully used as the trigger generator in ICF power conditioning system.     

A Design Model of Core Snubber for EAST NBI

A transformer type iron core snubber, as a protective device against the stray capacitance during the breakdown in EAST, is analyzed in detail. Three kinds of topology are presented. Then with the analysis for equivalent circuit, the ranges of three key parameters, i.e., secondary side resistance, leakage inductance and snubber inductance, are determined. By considering the saturation of the magnetic material, a design principle is also presented. A nearly 1:10 core snubber is tested. It is proved that a high permeability core with secondary resistor can restrain the discharge current effectively.     

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。     

Non-Destructive Screening for Thermal Second Breakdown

The feasibility of developing nondestructive screening techniques to determine the second breakdown vulnerability of semiconductor devices at submicrosecond pulse conditions has been demonstrated. In addition, it has been shownl that second breakdown can be nondestructively initiated under certain current limiting conditions without causing degradation in device operating characteristics or device second breakdown vulnerability level to subsequent pulses of electrical energy. A low energy current impulse damage mechanism at second breakdown initiation has also been observed. The experimental investigations were performed using 1N4148 diodes fabricated with various junction areas and a fixed diffusion depth. The complete results of this work are documented in Reference 1.     

Recent Advances in DC Methods of Particle Acceleration

Four recent developments have contributed significantly to broadening the scope of dc particle-acceleration systems: 1. Tandem principle of utilizing the generated high-voltage several times; 2. Insulating-core transformer for generating high-voltage dc power; 3. Inclined-field acceleration tube that minimizes the "total voltage effect, a previous limitation of dc acceleration systems; 4. Ion-source and beam-optical designs to increase useful ion intensities and to improve efficiency of transporting accelerated dc beams. These developments are currently being incorporated, in various combinations, into several dc accelerator designs, including: a. Sub-Mev electron and positive-ion accelerators with high beam power; b. Tandem Van de Graaff accelerators with at least 10 million-volt potential; c. Powerful Tandem accelerator at moderate voltage and very high current. Typical systems arising out of these advances are described in the light of applications now being exploited in research and industry.     

电流型银激活探测器标定技术

为测量DPF脉冲中子产额,设计了电流型银激活探测器。该探测器由中子慢化体、天然银片、塑料闪烁体和光电倍增管组成。定义了该探测器测量DPF快脉冲中子产额时的探测灵敏度。采用高压倍加器稳态中子源对电流型银激活探测器的探测灵敏度进行了标定。稳态中子源的绝对中子产额由伴随粒子法给出。通过计算机自动记录探测器在饱和照射后其输出电流随时间的变化曲线,通过分析变化曲线求解特征参数,进而得到电流型银激活探测器在距离14 MeV脉冲中子源1 m处时的探测灵敏度为1.843´10⁹ nA^－1。在包含因子k为2时,探测灵敏度的扩展不确定度小于17.5 %。     

Spatiotemporal control of femtosecond laser filament-triggered discharge and its application in diagnosing gas flow fields

Precise control of the discharge in space and time is of great significance for better applications of discharge plasma. Here, we used a femtosecond laser filament to trigger and guide a high-voltage DC pulse discharge to achieve spatiotemporal control of the discharge plasma. In space, the discharge plasma is distributed strictly along the channel generated by the femtosecond laser filament. The breakdown voltage threshold is reduced, and the discharge length is extended. In time, the electrical parameters such as the electrode voltage and the electrode gap affect discharge delay time and jitter. By optimizing the parameters, we can achieve sub-nanosecond jitter of the discharge. Based on the spatiotemporal control of the discharge, we applied filament-triggered discharge for one-dimensional composition measurements of the gas flow field. Besides, the technique shows great potential in studying the spatiotemporal evolution of discharge plasma.     

通道电子倍增器的性能研究

本文介绍用电子和正电子束流测试单通道电子倍增器的高压坪曲线、脉冲幅度分布和效率曲线;还用电子束流测试了阈电压和坪起始电压随电子能量的变化、增益随工作电压的变化、脉冲幅度与电子能量的关系、脉冲幅度和计数率随束流强度以及本底随工作电压的变化关系。