小型电子直线加速器脉冲调制器输出电路的拓扑结构

在小型电子直线加速器中使用各种脉冲调制器输出电路拓扑结构以适应不同的调制器负载要求。对不同的拓扑所遇到的一些共同性问题进行了详尽的叙述与讨论。     

Temporal characteristic analysis of single event effects in pulse width modulator

In this paper,the nature and origin of single event effects (SEE) are studied by injecting laser pulses into different circuit blocks,combining with analysis to map pulse width modulators circuitry in the microchip die.A time-domain error-identification method is used in the temporal characteristic analysis of SEE.SEE signatures of different injection times are compared.More serious SEE are observed when the laser shot occurs on a rising edge of the device output for blocks of the error amplifier,current sense comparator,and T and SR latches.     

大功率固态调制器组元电路设计与实验

文章介绍了用于直线加速器的大功率固态调制器组元电路设计,电路中采用了3.3 kVIGBT及大尺寸纳米晶磁环,磁环采用国产材料,在施加偏磁情况下磁芯伏秒数达到0.006.介绍了驱动电路、反向吸收、偏磁等辅助电路.最后给出了动态磁性能测量结果及组元电路主要波形.     

Research of magnetic self-balance used in a repetitive high voltage rectangular waveform pulse adder

Compared with a sinusoidal operation, pulsed operation has more homogeneity and more efficiency in dielectric barrier discharge. In this paper, an improved pulse adder is designed and assembled to create repetitive high voltage rectangular pulses when resistive loads or capacitive loads exist. Beyond the normal pulse adder based on solid-state switches, additional metal–oxide–semiconductor field effect transistors are used in each stage for a faster falling edge.Further, the voltage difference between stages is eliminated by balancing windings. In this paper,we represent our theoretical derivation, software simulations and hardware experiments on magnetic self-balance. The experiments show that the voltage difference between stages is eliminated by balancing windings, which matches the result of simulations with almost identical circuits and parameters.     

A calculation model for breakdown time delay and jitter of gas switches under hundred-nanosecond pulses and its application in a self-triggered pre-ionized switch

In this paper,a calculation model for the breakdown time delay and jitter of gas switches under hundred-nanosecond pulses is proposed and applied in a self-triggered pre-ionized switch.The effects of injection time of pre-ionization,pulse rise time,and the pre-ionization jitter are discussed and verified through experiments.It indicates that the pre-ionization should be injected when the electric field is high enough in the gap,injection after 80％peak-time can ensure its effectiveness.Then the statistical time delay jitter will be determined by the pre-ionization jitter,which is an intrinsic restriction of the self-triggered switch.However,when the changing rate of the pulsed electric field exceeds a certain value,the breakdown time delay jitter can be partly offset in the formative stage because the formative time delay has an exponential relationship with the electric field.Therefore,lower time jitter can be obtained under pulses with a shorter pulse rise time.In general,the results of the calculation model agree with the experimental results,and the experimental parameters which lead to a low jitter can also be used as a reference.     

微带传输线在高速脉冲发生器中的应用

在高速脉冲发生器的制作中．电路分布参数是影响高速脉冲发生器技术指标的主要因素。在高速脉冲发生器设计中引入微带传输线技术,通过对微带线的设计、计算和制作,在仪器电路中采用微带线进行高速脉冲传输,从而消除了电路板分布参数对脉冲前、后沿的影响,提高了仪器输出脉冲信号的各项参数指标。     

用于非弹性散射谱和俘获谱测量的高压脉冲电源设计

设计了用于非弹性散射谱和俘获谱测量的时间、幅度可调离子源脉冲电源。采用单端正激式结构和软开关技术,逆变输出高压脉冲,占空比从0．1～0．5可调,最小脉宽8μs。目前该脉冲电源已成功应用于煤质快速分析仪中,测量精度明显优于直流方式。     

Criterion of Magnetic Saturation and Simulation of Nonlinear Magnetization for a Linear Multi-core Pulse Transformer

The linear multi-core pulse transformer is an important primary driving source used in pulsed power apparatus for the production of dense plasma owing to its compact,relatively low-cost and easy-to-handle characteristics.The evaluation of the magnetic saturation of the transformer cores is essential to the transformer design,because the energy transfer efficiency of the transformer will degrade significantly after magnetic saturation.This work propses analytical formulas of the criterion of magnetic saturation for the cores when the transformer driver practical loads.Furthermore,an electric circuit model based on a dependent source treatment for simulating the electric behavior of the cores related to their nonlinear magnetization is developed using the initial magnetization curve of the cores.The numerical simulation with the model is used to evaluate the validity of the criterion.Both the criterion and the model are found to be in agreement with the experimental data.     

高斯响应滤波器的设计及其在超短脉冲束流位置测量中的应用

以超短中激励高斯响应滤波器，可获得一串衰减正弦振荡，延长了等效的信号持续时间，从而使信号变得易于处理，此技术应用在合肥国家同步辐射光源超短脉冲束流位置测量中，极大地改善了事流诊断效果。     

脉冲调制器稳定性监控中的数据采集与处理

设计采用反馈控制的方法改善脉冲调制器输出高压脉冲幅度稳定性,分析了实现稳定性目标对数据采集系统软、硬件的要求,介绍了相关的实验测试和信号处理方法。数据采集系统由Stratix ii FPGA开发板、AD6645、上位PC机组成,借用差分放大器提高测量分辨率。数据处理采用脉冲采样样本均值作为表征幅度的特征量,并采用平均、插值、数字滤波、BP神经网络等方法来提高幅度监测值的分辨率能力和抗干扰能力。     

千道脉冲幅度分析器设计及应用

介绍一种1k道分辨率的脉冲幅度分析器,设计中采用了虚拟仪器架构.系统由完全隔离的模拟处理前端与数据采集、控制及应用系统接口、缓冲存储器等部分组成,可以胜任对多种核探测器的脉冲幅度采集和数据分析.对CPLD控制的数据采集操作、应用层和系统层的程序设计等技术细节进行了分析和说明.利用本文原理,可以设计出更高性能的脉冲幅度分析系统.     

Optimized analysis of sharpening characteristics of a compact RF pulse source based on a gyro-magnetic nonlinear transmission line for ultrawideband electromagnetic pulse application

We constructed a compact high-power RF pulse generator based on a gyro-magnetic nonlinear transmission line (GNLTL) to produce a high-voltage pulse with a sub-nanosecond rise time and a relatively high repetition rate, which shows great potential for application in the high-power ultrawideband electromagnetic effect, etc. The influence of incident pulse parameters (rise time and voltage amplitude) and line length on the sharpening characteristics of the GNLTL were investigated experimentally to optimize the rising rate of the modulated pulse front. Based on the GNLTL equivalent circuit model consisting of an LC ladder network, the rise time, the voltage conversion coefficient and the rising rate properties of a modulated pulse were also numerically analyzed in a wider range. The results show that a>90 kV RF pulse with a rise time of 350 ps and a repetition rate of 1 kHz in burst mode is produced by the GNLTL at an axial biasing magnetic field of 22 kA m⁻¹ and a line length of 30 cm under the condition of a 70 kV incident pulse. Applying a faster and higher incident pulse is conducive to improving the sharpening effect of the GNLTL. Furthermore, within a certain range, increasing the line length of the GNLTL not only reduces the rise time, but increases the voltage conversion coefficient and the rising rate of a modulated pulse. Furthermore, considering the energy loss of ferrite rings, there is an optimal line length to obtain the fastest rising rate of a modulated pulse front edge.     

多道脉冲幅度分析器死时间修正方法探讨

核分析能谱测量所用的多道脉冲幅度分析器,在进行模数转换时需要一定的时间,会使分析器产生漏计数,给测量分析带来误差,需要对死时间进行修正。针对这种情况,探讨了两种有效的死时间修正方法。     

The regulation of memory effect and its influence on discharge properties of a dielectric barrier discharge driven by bipolar pulse at atmospheric-pressure nitrogen

The regulation of memory effect that the residual charges generated during and after discharge act on the initiation and development of subsequent discharge is explored by adjusting the pulse parameters,which have an influence on the discharge characteristics.The memory effect is quantified by the measurement of 'wall voltage'through a series of reference capacitors.The influences of memory effect on the discharge properties corresponding to rising/falling time 50-500 ns,pulse width 0.5-1.5 μs,and frequency 200-600 Hz are analyzed.It is found that the'wall voltage'increases from 1.4 kV to 2.4 kV with rising/falling time from 50 ns to 500 ns,it varies in the range of 0.18 kV with frequency of 200-600 Hz,and 0.17 kV with pulse width of 0.5-1.5μs.The propagation velocity of wavelike ionization under the negative pulse slows down from 2184 km s-1 to 1026km s-1 as the rising/falling time increases from 50ns to 500ns due to the weakening of the electric field by the surface memory effect.More intense and uniform emission can be achieved through faster rising/falling time and higher frequency based on the volume memory effect,while pulse width has less influence on the emission uniformity.Furthermore,similar laws are obtained for spectral and discharge intensity.Therefore,the memory effect is most effectively regulated by rising/falling time,and the discharge properties are affected by the surface and volume memory effect.     

HT-7中长时间低漂移模拟积分器的研制

电磁测量是托卡马克装置中最基本的诊断方法,通常利用磁感应原理来测量HT-7装置内部磁场和磁通,因此需要用积分器对磁测量的输出信号进行积分。讨论了单运放模拟积分器的特点,提出了利用实时积分漂移补偿的方法设计新型积分器,解决了积分过程中积分器本身的等效输入偏移量、温度漂移及地噪声等带来的积分误差。给出了系统原理和设计框图,并在HT-7超导托卡马克的实验中,验证了该积分器能够满足等离子体长时间放电对积分器在积分精度和噪声精度上的要求。     

Improvements in time resolution and signal-to-noise ratio in a compact pico-second pulse radiolysis system

A compact pico-second pulse radiolysis system has been developing at Waseda University for studying primary processes in radiation chemistry. The system is composed of a photo-injector system and a pico-second all-solid-state laser system. An infrared (IR) and an ultraviolet (UV) laser pulses are obtained from mode-locked Nd:YLF laser system and used for generation of the white light continuum as a probe light and the irradiation to the Cu cathode of a photo-cathode RF-gun, respectively. To improve signal-to-noise (S/N) ratio and time resolution of this pulse radiolysis system, we optimized both probe light and pump electron beam. As a result, our pico-second pulse radiolysis system has been enough to study the primary processes of radiation chemistry. The experimental results and the improvements of our system are described in this paper.     

一种仿核脉冲随机信号发生器的设计与实现

针对模拟核信号发生装置的研究,本文提出了一种高精度、高灵活度的信号发生器的研制思路。利用Matlab可以便携地实现核信号的数字模拟,保证核脉冲信号的时间特性、幅度特性和脉冲形状特性。由Lab VIEW设计的上位机软件可以提供较好交互方式,便于灵活地调节发生器的各项参数,并进行相应的谱数据分析及显示。硬件电路主要由MCU、FPGA、SRAM、10 bit高速DAC、低通滤波及放大电路构成。初步的测试结果表明:该信号发生器满足核信号在时间间隔和幅值的随机分布特性,能量范围及计数率可调,谱数据的统计分析,高精度的信号输出,为仿核信号发生器的研制与改进提供了思路。     

Analysis of an Ar plasma jet in a dielectric barrier discharge conjugated with a microsecond pulse

In this work, an Ar plasma jet generated by an AC-microsecond-pulse-driven dielectric barrier discharge reactor, which had two ring-shaped electrodes isolated from the ambient atmosphere by transformer oil, was investigated. By special design of the oil insulation, a chemically active Ar plasma jet along with a safe and stable plasma process as well as low emission of CO and NO_x were successfully achieved. The results indicated that applied voltage and frequency were basic factors influencing the jet temperature, discharge power, and jet length, which increased significantly with the two operating parameters. Meanwhile, gas velocity affected the jet temperature in a reverse direction. In comparison with a He plasma jet, the Ar plasma jet had relatively low jet temperature under the same level of the input parameters, being preferable for bio-applications. The Ar plasma jet has been tested to interact with human skin within 5 min without the perception of burnt skin and electrical shock.     

核电站低压厂用变压器零序保护的分析与改进

核电站低压厂用变压器中性点零序保护采用"定时限"设计,多次出现因低压负荷回路发生单相接地故障引起的低压厂用变压器零序保护越级动作事件。梳理低压厂用变压器零序保护整定原则和分析上下级差保护配合要求,提出低压厂用变压器零序保护采用"定时限+反时限"两段式保护改进方案,经过保护校验和现场验证,改进方案可在核电站应用和推广。     

Study on the discharge mechanism and EM radiation characteristics of Trichel pulse discharge in air

The Trichel pulse stage is an unstable stage of negative corona discharge that can also involve electromagnetic (EM) radiation signals. In this paper, the discharge mechanism and radiation characteristics of the Trichel pulse are studied in the needle-plate electrode configuration. The Trichel pulse current and its EM radiation signals are measured at different applied voltages. The results show that Trichel pulse discharge changes from the random pulse stage to the continuous pulse stage as the applied voltage increases. During these different stages, the normalized shape of the Trichel pulses remains unchanged, while the frequency of the EM radiation generated by the discharge remains unchanged. The discharge mechanism and EM radiation characteristics of the Trichel pulse are theoretically analyzed in the different stages. Both the positive ion sheath and the negative ion cloud play key roles in the formation of the Trichel pulse. The EM radiation signal is generated by the rapidly changing Trichel pulse current, and the Trichel pulse current waveform determines the characteristics of the EM radiation signal.