用于2.5MeV质子静电加速器ns脉冲装置的晶体管移相倍频器

本文介绍一个幅-相和相-幅特性均优良、能跟随加速器长期稳定运行的晶体管移相倍频器。它用于我所2.5MeV质子静电加速器ns脉冲装置的电子线路中。调节该器输出电压幅值和相位,能有效地控制频率为2MHz、宽度为10—20ns的脉冲束沿中心轨道横向偏转的张角大小和对称性。     

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。     

Design and Optimization of Low-Noise Wide-Bandwidth Charge Preamplifiers for High Purity Germanium Detectors

Design criteria for low-noise wide-bandwidth charge-sensitive preamplifiers for highly-segmented HPGe detectors are presented. The attention is focused on the optimization of the preamplifier noise, long-term gain stability, and bandwidth. The charge-sensitive preamplifiers of AGATA, i.e., the Advanced GAmma Tracking Array detector for next generation nuclear physics experiments, have been designed, realized and optimized using the proposed techniques. The circuit, in conjunction with the detector, provided an Equivalent Noise Charge of 101 electrons r.m.s., a rise time of ~ 8.3 ns, no appreciable line shift in long term acquisitions, a dynamic range of as much as 92 dB. An analytical study of the circuit is made. Computer simulations and experimental results are shown and critically discussed.     

合肥光源储存环工作点测量系统设计

为适应合肥光源储存环工作点测量的需要,设计了基于Zynq的工作点测量系统。该测量系统由前端电子学、FPGA、ARM和上位机构成,系统结构紧凑,成本较低,功能丰富,可在线编程满足不同机器研究实验的需求。论文论述了参数化白噪声信号和扫频信号的产生以及相应的信号处理过程。在线实验结果表明,工作点在扫频激励模式下,水平和垂直方向的统计分辨率分别为0.0006/0.0001,白噪声激励模式下,水平和垂直方向的统计分辨率分别为0.0007/0.0036。系统进一步改进,还可测量同步振荡阻尼时间、色品等,为合肥光源存储环提供更丰富的束流测量手段。     

Effect of pulse voltage rising time on discharge characteristics of a helium-air plasma at atmospheric pressure

In this paper,the influence of voltage rising time on a pulsed-dc helium-air plasma at atmospheric pressure is numerically simulated.Simulation results show that as the voltage rising time increases from 10 ns to 30 ns,there is a decrease in the discharge current,namely 0.052 A when the voltage rising time is 10 ns and 0.038 A when the voltage rising time is 30 ns.Additionally,a shorter voltage rising time results in a faster breakdown,a more rapidly rising current waveform,and a higher breakdown voltage.Furthermore,the basic paraneters of the streamer discharge also increase with voltage rise rate,which is ascribed to the fact that more energetic electrons are produced in a shorter voltage rising time.Therefore,a pulsed-dc voltage with a short rising time is desirable for efficient production of nonequilibrium atmospheric pressure plasma discharge.     

ns脉冲中子发生器切割板电容值测量

给出了利用扫描谐振法测量ns脉冲中子发生器切割电容值的方法，并给出了切割板在静态情况下以及不同束流的动态情况下电容值的大小。     

用饱和增益开关法压缩KrF准分子激光脉冲

为提高激光作用于靶上的功率密度和耦合效率，需对目前的激光进行脉宽压缩。本工作采用饱和增益开关法，利用预放大器的放大特性对前端输出的非相干光进行了脉宽压缩，最后将脉宽为23ns的种子光压缩到了12ns，且可根据需要在5~20ns内变化。     

多束脉冲作用下韧致辐射转换靶照射量模拟

20MeV的强流脉冲电子束经加速聚焦后轰击韧致辐射转换靶,在产生脉冲X光的同时将大量能量沉积在靶内,导致靶材迅速膨胀飞散。在多个束脉冲作用下,后续脉冲由于靶材密度的降低可能无法产生足够的X光照射量。本文采用Monte-Carlo软件MCNP以及流体动力学软件ANSYSAUTODYN对靶材的动力学响应以及各脉冲所能产生的照射量进行了数值模拟,结果表明,在3个间隔500ns的20MeV、2kA、70ns、束斑1.5mm（FWHM）的电子束脉冲作用下,X光照射量无明显降低。     

一个用于加速器时间分辨分析系统的纳秒高压脉冲装置

设计了一个纳秒高压脉冲装置，脉冲电压可达16kV，前沿上升时间为10ns，此装置已用于加速器时间分析系统，系统的物理分辨时间小于0．8％，时间半高宽为25ns。     

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％.     

快响应门控光电倍增管设计

门响应时间和消光比是门控光电倍增管的两个重要性能参数。介绍了将俄制CHφT5型光电倍增管改制为门控光电倍增管的设计。采用控制光电倍增管第二聚焦极的方法,设计快响应门控制电路,使门控光电倍增管具有3个量级以上的消光比,开门延迟响应时间为70 ns,光电倍增管恢复输出的时间为20 ns。光电倍增管灵敏度降低了20%。     

On the Performance of Grid-Controlled Photomultipliers in the Nanosecond Region

Controlled photomultipliers may be used for analysing modulation frequencies and other time parameters of radiation, which lie beyond the bandwidth or the time parameters of secondary emission systems. On the basis of the electron-optical characteristics of a control system for photomultipliers with two control grids, the properties to be expected are investigated for quasi-stationary operation and under consideration of transit-time effects. Due to the electron-optical properties of the control system, disturbing residual pulses are nearly made ineffective. It is experimentally shown that when using two controlled photomultipliers of the Type SKP-1 as coincidence elements at a distance of 1.5 ns of the gating intervals, the pulse rate decreases to less than 0.1 % (Fig. 12) compared with the rate at a time coincidence of the gating intervals. These values do not only depend on the photomultiplier, but also on the length of the light pulses and the period of the control voltage. The half-width of the coincidence between a light pulse and an electrical control pulse is smaller than 0.5 ns.     

Analysis of microwave propagation in a time-varying plasma slab with particle-in-cell simulations

Continuous microwave propagation through a time-varying plasma and frequency up-conversion has been demonstrated by particle-in-cell(PIC) simulation.In principle,it is possible to transform a 2.45 GHz source radiation to an arbitrary larger frequency radiation.The energy conversion is also obtained by the theoretical analysis and has been testified by PIC simulation.The source wave was propagating in a parallel plate waveguide locally filled with the ionized gas.In this paper we would discuss the effects of the rise time,the plasma length,the switching time and the collision frequency on the energy conversion,and the methods to improve the upshift wave energy are proposed.We also put forward the new concept of the critical values of the rise time and the source wave amplitude to provide a theoretical basis for the selection of parameters in the experiments.     

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.     

BEPC Ⅱ直线加速结构的整管RF特性计算

为了在加工前对行波盘荷波导加速管的整管RF特性有所了解,在ANSYS软件中利用重新设计的轴对称型耦合器来替换实际的三维耦合器建模,充分利用加速结构的轴对称特性,并在使用较少计算资源和时间的情况下,仅利用1台计算机即可完成对整根加速管全部特性的计算,从而得到其整管RF特性。以BEPC Ⅱ直线加速器所采用的3 m长加速结构为例,使用本方法进行计算得到的填充时间、衰减常数及带宽分别为856 ns、0.56 Np及3.55 MHz,而实测结果分别为830 ns、0.57 Np及4.7 MHz。总体上,ANSYS模拟结果与实测结果较为一致。由此,模拟计算可为实际设计和加工提供指导。     

100 MHz and 100 Mbit Recording and Readout Instrumentation Systems for Electromagnetic Field Perturbations

The requirement for a wideband recording capability for instrumenting electromagnetic fields with nanosecond rise time perturbations and long duration reactions lead to the development of a modulated laser beam analog recorder. The original concept of the recorder yielded 100 MHz bandwidth records of ±40 db dynamic range of approximately 25 ?sec duration but required synchronization of the event to the rotating mirror camera of the recorder. Normalization of data required digital computer processing of densitometer conversion of film density data to analog electrical signal. An improvement of the original system, which permits continuous recording up to several minutes at 100 Mbit digital writing solves the major shortcomings of the analog recorder. Using techniques of signal conditioning and laser beam splitting and modulation of the previous system, the data stream is split into four channels recorded simultaneously and continuously on moving 70 mm film in a four-to-one interlace pattern. Each channel is organized into discrete blocks with data synchronizing words to provide block and timing identification. The physical arrangement of the recorder is such that film readout is effected on the same transport deck. Simultaneously scanned data tracks generate a parallel serial data train which is buffered, multiplexed, and recombined to produce the serial data stream.     

低功耗和快速补偿的光电倍增管偏置电路

介绍了由晶体管化的光电倍增管偏置电路的研究,该电路具有功耗低,稳定可靠,输出脉冲上升时间快,能量分辨高、脉冲线好、恢复时间快等优点。     

微通道板光电倍增管在高能物理实验中的应用前景

一种用微通道板作为榈增极的新型光电倍增管已研制成功，它的脉冲上升时间小于１ｎｓ，本文介绍了它的一般性并讨论了它的抗磁场性能和作为位置灵敏探测器的可能性。     

A New Preamplifier for Drift Chambers

We have developed a new preamplifier for drift chambers with a high gain (20mV/105 e), high speed (5 ns rise time) and low power consumption (28 mW). Some of its design considerations and performances are described. A monolithic version of the preamplifier is also developed.     

快速电荷灵敏放大器

本文介绍一种快速电荷灵敏放大器,它在基本的共源极-共基极组态放大器中插入一个共集电极组态放大节,改善了系统特征方程的根轨迹,增大了回路增益,从而有效地提高了放大器的瞬态响应特性。在外接零电容时上冲小于10％情况下,上升时间小于4.5ns,等效噪声线宽FWHME(Si)约1keV