Simulation Analysis of Transmission-Line Impedance Transformers for Petawatt-Class Pulsed Power Accelerators

Based on the transmission line code TLCODE, a 1D circuit model for a transmission- line impedance transformer was developed and the simulation results were comp...     

Optimal Matching of Magnetic Pulse Compressor

Energy transmission efficiency in the magnetic pulse generators varies with saturated time of magnetic switch. An optimal matching time exists and depends on the compression ratio, under which, the energy transmission efficiency can reach approximate 100%. The equation of required magnetic core volume is obtained by taken into account the optimal matching mode. It indicates that a great reduction on the volume is feasible under the optimal matching mode. The circuit simulation code-PSPICE is also introduced to simulate a 3-stage magnetic pulse compressor, and the results are in accordance with those of equivalent circuit analyses.     

Experimental Study of Reversely Switched Dynistor Discharge Based on Gap Breakdown Load

Breakdown characteristics of a gap breakdown load was investigated in this study, and a Reversely Switched Dynistor (RSD) discharge circuit was designed based on the load. Based on the characteristics of the load the RSD discharge circuit was improved and optimized. The volume of the magnetic switch was reduced. To protect the thyristor and RSD, a diode was anti-parallely connected with the thyristor, which reduced the time requirement when a power voltage was applied to RSD. Experimental results show the circuit designed in this study can switch a high voltage and high current smoothly, and allows the power voltage to change in a wider range.     

低能加速器开关电源研制

利用直流脉宽调制技术以及半桥变换电路,为一种低能电子直线加速器成功研制阳极开关电源。根据开关电源的特点,对该电源中低压和高压部分进行详细设计。低压部分采用SG1525A为控制核心,实现脉宽调制、软启动、稳压调节以及过压保护功能。该开关电源主要指标:输出电压0~800V,最大电流400 m A,工作频率为18.5 k Hz,纹波峰值系数为0.9‰,达到设计要求。     

120路簇射计数器读出电子学系统

120路簇射计数读出电子学系统,主要由采样保持电路、多路模拟数字转换器及模拟总线组成。为了提高整个系统的装配密度和可靠性并减小环境温度变化的影响,专门设计了一种薄膜混合集成采样保持电路。采用了计算机在线校正方法,解决了放大器增益变化、积分非线性、模拟开关台阶和传输电缆干扰等引起的测量误差问题。系统的主要指标为:线性优于0.2％,σ噪音约为1.3BADC道,串扰优于1％,Z向位置分辨优于0.6％(SQS簇射计数器模型)。     

基于3D Si PIN阵列热中子探测器的变增益宽动态前端读出电子学设计

基于Si CMOS技术的前端读出ASIC主要是根据3D Si PIN阵列热中子探测器的输出信号特性设计的。所设计的读出ASIC的主要电路模块包括电荷灵敏放大器（CSA）、模拟开关设计、具有三级电荷灵敏自动转换的自动增益控制模块（AGC）、相关双采样（CDS）和基准电流源电路。仿真结果表明,前端电路的输入动态范围为10 fC~80 pC。根据热中子探测器输出信号特性设计的ASIC的3个增益系数分别为19 V/pC、039 V/pC和94 mV/pC。所设计的ASIC的积分非线性小于 1%。单通道静态功耗约为 536 mW。零输入探测器电容时的等效噪声电荷为2416e-。计数率可达1 MHz 。     

控制棒驱动机构动态提升特性研究

基于控制棒驱动机构的磁路和电路方程以及对控制棒驱动机构动态提升过程分析,分别推导出系统静态过程和动态过程的磁路-电路-机械运动耦合方程.采用解析解的方法求解提升起始电流和提升起始时间.采用ASME规范推荐的动态分析的数值仿真方法模拟控制棒驱动机构动态提升过程,分析磁极和衔铁间不同设计间隙下系统的提升特性.结果表明,衔铁起始提升时间随着设计间隙增大而增大,且设计间隙越大,提升所需时间越长;提升速度随着时间的增加而增大,且随着时间的增加,提升加速度增大,设计间隙越小,提升结束时的冲击加速度越大.     

Numerical Analysis of the Arc Plasma in a Simplified Low-voltage Circuit Breaker Chamber with Ferromagnetic Materials

This paper is devoted to the simulation of the arc plasma in a simplified low-voltage circuit breaker chamber. Based on a group of coupled governing equations, a three-dimensional （3-D） arc plasma model is built and solved by a modified commercial code. Firstly, this paper presents a solution of the stationary state of the arc plasma and discusses the distribution of some parameters throughout the chamber. Secondly, with the ferromagnetic materials included, the balance of the stationary state is broken and a transient course is calculated. In light of the simulation results, the temperature distribution sequence, the arc motion and the plasma jet are then described and analyzed in detail.     

套管式直流蒸汽发生器动态实时仿真研究

基于基本的流体质量、能量和动量守恒原理,建立了套管式直流蒸汽发生器的动态数学模型。该模型采用集总参数和移动边界的建模方法,将直流蒸汽发生器流道分为欠热段、沸腾段和过热段。采用Gear算法求解,对建立的模型进行稳态和动态仿真,并利用RELAP程序进行校验。结果表明：所建立的模型是正确和有效的,能用来进行直流蒸汽发生器的动态特性实时仿真。     

微秒脉冲电流的测量

简要介绍Ｒｏｇｏｗｓｉｋ线圈的测量原理,给出了测量系统的构成和测量结果,测量结果表明,采用谐振逆变电源作充电器和采用流管作放电回路主开关,使得脉冲发生器具有脉冲放电幅度晃动小等优点。     

“春雷号”有界波EMP模拟器暂态过程的计算

对“春雷号”有界波ＥＭＰ模拟器主开关动作前后的暂态过程建立了相应的等效电路及微分方程，用定步长龙格－库塔法进行了数值求解，并与实测波形进行了比较，提出了改善输出波形的几种方法。这对于模拟器的设计、调整及改进都有一定的意义。     

10MW高温气冷堆的集总参数动态模型

应用基本的质量、能量和动量守恒原理，建立了10MW高温气冷堆的动态数学模型。该模型采用了集总参数的建模方法，将反应堆按照不同热工水力学属性划分为多个节块，并采用了具有6组缓发中子的点堆中子动力学公式。对建立的模型进行了动态仿真。结果表明，所建立的模型能够用来进行反应堆的动态特性仿真。     

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.     

Convection effect on an arc plasma evolution process in a two parallel contact system

A low voltage circuit breaker(LVCB) is an important piece of protection equipment which will switch off the fault current in a power system. The moving contact of a low voltage circuit breaker with a higher rated current consists of two parallel contacts. Therefore, the convection effect on the air arc evolution process in a two parallel contact system is analyzed. A threedimensional(3 D) magneto–hydro–dynamic(MHD) model of arc simulation is built. In this model, the anode consists of two parallel contacts and a bonding conductor. A nonlinear voltage–current density characteristic is employed to represent the near-anode and near-cathode voltage. The current density, arc voltage and currents through every contact are obtained. The influence of convection and conduction on the arc evolution process are quantitatively calculated. The displacements of the arc roots are obtained and the asymmetry of the arc root motion is analyzed. The arc evolution process of a two parallel contact system is preliminarily revealed.     

Experimental Study on Triggering Characteristics of a Surface Flashover Triggered Vacuum Switch

Triggering characteristics of triggered vacuum switch （TVS）, including the discharge delay time, delay jitter, range of operational voltage and peak of pulsed current, are investigated. Both structure and experimental circuit of TVS are presented. The results indicate that TVS, as a surface flashover triggering device with high dielectric permittivity material, is with excellent triggering characteristics. When the hold-off voltage reaches 120 kV, the minimum operational voltage is 1.3 kV, and the minimum discharge delay time and jitter are 100 ns and ?10 ns, respectively. The peak current is up to 240 kA when the operational voltage reaches 100 kV. TVS can well satisfy the main demands of high voltage and current applications, and can also be used under a multi-crowbar circuit.     

Statistical Modeling of Semiconductor Devices for the Tree Environment

The modeling of semiconductor devices for use with circuit analysis computer codes is a very important endeavor. The accuracy of the model ultimately will determine the accuracy of the analysis and its relation to actual circuit operation. The transistor model used in the Autonetics Transient Radiation Analysis by Computer (TRAC) code is discussed. Particular emphasis is placed on the simulation of radiation-induced photocurrent in the p-n junctions. The photocurrent generator is first derived for a single junction. The result is then extended to the transistor model by appropriately combining two junctions which interact. The interaction is accomplished by including a current transport factor at each junction, as in the Ebers and Molll) formulation. The photocurrents are then examined in terms of defining equations which lead to the criterion for measuring the photocurrent parameters which, in turn, are related to the conventionally defined primary photocurrents in the devices.     

基于3单元模型的怀特电路特性

文章基于3个单元的怀特电路模型，重点分析了回路中各个部件对系统特性的影响。结果表明，谐振电抗器的互感系数的不一致性将激励寄生频率，从而在每个谐振电抗器与电容支路中产生寄生电流，并导致磁铁电流的畸变。在理论分析基础上提出了电源及谐振部件的设计原则。     

对中国实验快堆(CEFR)某些系统和设备核安全分级的探讨

简要叙述了先进堆型模块式高温气冷堆(MHTGR)、先进沸水堆(ABWR)和中国实验快堆(CEFR)的良好安全特性并给出了它们某些系统和设备安全级别与现行压水堆PWR和沸水堆BWR的比较。据此,并通过对CEFR三回路、通风系统和柴油发电机组等安全功能的分析,从而对它们的安全分级提出了建议。     

Digital Computer Techniques for Determining Circuit Behavior in a Pulsed Nuclear Environment

Two digital computer circuit analysis programs which predict circuit response in a pulsed nuclear radiation environment are presented. One program requires that linear direct current equations be written manually and then programmed for computer solution. The other program generates the equations from topological circuit information and then solves the equations during the radiation burst automatically. Predictions generated by the automated program on four different circuits are verified experimentally.     

Application of cellular neural network (CNN) method to the nuclear reactor dynamics equations

This paper describes the application of a multilayer cellular neural network (CNN) to model and solve the nuclear reactor dynamic equations. An equivalent electrical circuit is analyzed and the governing equations of a bare, homogeneous reactor core are modeled via CNN. The validity of the CNN result is compared with numerical solution of the system of nonlinear governing partial differential equations (PDE) using MATLAB. Steady state as well as transient simulations, show very good comparison between the two methods. We used our CNN model to simulate space-time response of different reactivity excursions in a typical nuclear reactor.