纳秒闸控灯的研制

纳秒闸控灯是由快闸流管控制的一种低压放电灯,是一种上升时间快、持续时间短和重复频率可控的窄脉冲光源。由于其放电初始时刻可控制,在荧光寿命测量和其它短时间间隔的测量中,常用作时间定标信号。     

Zr-4合金管材的超声测厚

本文介绍了采用窄脉冲探头和脉冲回波法测量Zr-4合金管材壁厚的超声仪器和方法。壁厚测量是通过测量界面回波间隔时间来实现的。由于在信号处理和电路设计中作了改进,仪器可达到微米级测量精度。文中还介绍了采用金相实验方法标定参考标准管的工作。     

Zr-4合金管材的超声测厚

介绍了采用窄脉冲探头和脉冲回波法测量Zr-4合金管材壁厚的超声仪器和方法。壁厚 测量是通过测量界面回波间隔时间来实现的。由于在信号处理和电路设计中作了改进,仪器可达到微米级测量精度。文中还介绍了采用金相实验方法标定参考标准管的工作。     

辐射剂量测量的积分脉冲放电法

本文研究了辐射强度随时间迅速变化的辐射场剂量测量,提出积分脉冲放电法作为测量的基本方案,并设计了能在γ、X、中子混合场中工作的探测系统。     

西安脉冲堆脉冲参数测量装置研制

介绍了我国自主研制的第一套商用脉冲反应堆脉冲参数测量装置（西安脉冲堆脉冲参数测量装置）的设计方案、系统组成、工作原理、技术特点和应用情况。该装置是西安脉冲反应堆主控室控制台的主要仪表之一，具有脉冲参数测量和堆保护功能。装置采用微电子和计算机技术，实现了对反应堆脉冲工况下堆功率变化、脉冲波形与多个参数的实时自动测量与显示，并在功率超限时向反应堆保护系统和报警系统发出信号。文中对装置的工作特性做了描述，并对现场调试和运行情况作了简要介绍。     

Controlling Chaos of Semiconductor Laser Using Sliding Variable Structure Strategy

CHEL3300激光器首次尝试采用1套磁脉冲压缩快关控制的L-C反转电路实现3个独立的激光腔放电。通过调整磁脉冲压缩开关到各个放电腔电路的电感确保3个放电腔按照“天光一号”系统1次分束的要求以20ns的时间间隔依次放电。     

SSRF储存环注入脉冲电源的设计

本文介绍了采用固态半导体放电开关实现的1.7 kV、10 kA的Septum电源和7.8 kV、3.7 kA的Kicker电源,详细分析了两台脉冲电源的电容器充电电源、脉冲放电开关、放电回路结构、热漂移校正等问题.原型样机的结果表明,其电流幅度稳定性都优于±0.1%,其他主要指标均可达到设计要求.     

用于脉冲堆裂变总数测量的闪烁体探测器研制

采用波形积分法研制了用于脉冲堆裂变总数测量的闪烁体探测器,采用脉冲峰和脉冲坪信号分路引出的设计,同时测量裂变率相差较大的脉冲峰和脉冲坪。该探测器具有线性电流大、测量范围宽的特点,在测量小产额脉冲时更具优势。该裂变总数测量方法与其他方法获得的结果一致。     

真空弧离子源脉冲工作瞬间的放电行为

采用高速摄影和光谱诊断的方法研究了真空弧离子源脉冲工作瞬间的放电行为。拍摄了离子源放电瞬间吸氢电极上阴极斑的形成过程，分析了不同放电电流时阴极斑的发射光谱。实验结果表明，当脉冲工作电流为10^1—10^2A时，真空弧离子源放电区一般只有单个阴极斑，阴极斑的位置在同一次放电中的变化很小；较大的脉冲工作电流有利于提高阴极斑的温度，并最终导致氢离子浓度的增加，但也会使阴极材料的溅射更加严重，造成离子源等离子体品质下降。     

HT-7超导托卡马克上γ辐射的初步研究

尝试了在HT-7托卡马克准稳态等离子体实验平台上，对伽马辐射能谱与通量进行测量与分析。实验中，测量得到了不同放电条件下的伽马辐射能谱和通量的时间演化过程，观测到了丰富的伽马辐射行为。针对欧姆加热、低杂波、离子回旋波、离子伯恩斯坦波、长脉冲等不同放电条件下的伽马辐射行为做了研究，结合其它相关诊断数据，给出了初步的分析结果。     

梯形成形算法中成形参数与成形脉冲波形关系研究

在梯形成形算法理论基础上,利用模拟和实测核脉冲信号研究了梯形成形算法中衰减时间常数(τ_(trap))、达峰时间(n_a)与成形脉冲波形、滤波效果的关系,以及nb在分离堆积脉冲时的取值选择。研究表明,当且仅当τ_(trap)等于输入信号衰减时间常数时,成形脉冲对称;n_a值越大,滤波效果越好,脉冲宽度增加;n_b小于两个核脉冲信号发生的时间间隔时,采用梯形成形算法可分离堆积脉冲。     

中子脉冲堆积信号处理方法研究

在强辐射环境下探测中子时,探测器输出的脉冲信号时常会出现堆积的现象,从而导致脉冲波形和中子能谱的失真。本文针对脉冲堆积问题,提出了一种数字化的脉冲堆积判别与校正方法,首先通过计算脉冲信号一阶微分中的下冲过零点个数来判别脉冲堆积,然后基于构建的4种标准堆积脉冲模型（n+n、γ+γ、n+γ、γ+n）还原构成堆积的原始脉冲。实验结果表明,该方法能准确地判别脉冲堆积事件,在堆积脉冲时间间隔小至20 ns时仍能有效地还原原始脉冲,既提高了中子有效计数率又校正了畸变的中子能谱。     

Research of a fractional-turn ratio saturable pulse transformer and its application in a microsecond-range pulse modulator

As a combination device for a step-up pulse transformer and a magnetic switch,the saturable pulse transformer is widely used in pulsed-power and plasma technology.A fractional-turn ratio saturable pulse transformer is constructed and analyzed in this paper.Preliminary experimental results show that if the primary energy storage capacitors are charged to 300 V,an output voltage of about 19 kV can be obtained across the capacitor connected to the secondary windings of a fractional-tum ratio saturable pulse transformer.Theoretical and experimental results reveal that this kind of pulse transformer is not only able to integrate a step-up transformer and a magnetic switch into one device,but can also lower the saturable inductance of its secondary windings,thus leading to the relatively high step-up ratio of the pulse transformer.Meanwhile,the application of the fractional-turn ratio saturable pulse transformer in a μs range pulse modulator as a voltage step-up device and main switch is also included in this paper.The demonstrated experiments display that an output voltage with an amplitude of about 29 kV,and a 1.6 μs pulse width can be obtained across a 3500 Ω resistive load,based on a pulse modulator,if the primary energy storage capacitors are charged to 300 V.This compact fractional-turn ratio saturable pulse transformer can be applied in many other fields such as surface treatment,corona plasma generation and dielectric barrier discharge.     

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.     

Verification of the pulse height tally in MCNP 5

Pulse height tallies are commonly used in Monte Carlo codes to predict detailed measured photon spectra for spectrometry purposes. The pulse height tally is unique among the various tallies in MCNP. Unlike flux or current tallies, which are calculated as soon as the particle exits or collides in the cell, the entire set of tracks for a history must be completed before the pulse height tally can be made. The objective of this work was to verify the pulse height tally and prepare to verify the new MCNP 5 variance reduction features with the pulse height tally.In this paper, we give details to the analytic solution of the pulse height distribution using a modification to Shuttleworth’s fictitious elements, report MCNP 5 results for the pulse height tally, energy deposited and current tallies for the problem.     

Detecting the meteoroid by measuring the electromagnetic waves excited by the collision between the hypervelocity meteoroid and spacecraft

The electromagnetic pulse excited by the collision between a hypervelocity meteoroid and a spacecraft is studied both numerically and theoretically. It is found that there are two kinds of electromagnetic pulse. The high-frequency electromagnetic pulse may be excited by the sum of all the electric dipoles. Each electron can be considered as an electric dipole. The low-frequency electromagnetic pulse is produced by the Langmuir oscillation of electrons. The energy flux density and the duration time of the excited low-frequency electromagnetic pulse by the meteoroid are also studied in the present paper. It is shown that the energy flux density increases as either the impact speed or the mass of the meteoroid increases. It is also shown that the duration time decreases as both the impact speed and the mass of the meteoroid increase. By measuring the strength and the duration time of the electromagnetic pulse excited by the collision between the hypervelocity meteoroid and spacecraft, we can estimate the speed and the mass of the hypervelocity meteoroid, which will be helpful in space flight and space exploration.     

程控中子管老炼台的研制

程控中子管老炼台采用计算机控制技术,以中子管内的真空度和高压击穿情况为判据,决定高压脉冲电压幅度和限流电阻的增加或减少,对老炼工艺过程、高压脉冲 " /-"极性和限流电阻的转换进行自动控制,实时记录老炼过程的数据及相关信息.     

Effect of pulse waveform on plasma sheath expansion in plasma-based ion implantation

In this paper, the effect of the pulse waveform on plasma sheath evolution around a diamond-shaped target has been simulated using fluid dynamic model in the context of plasma-based ion implantation (PBII). The implanted parameters of ions such as ion-implanted energy, impact angle and impact current have also been studied under different pulse shapes. Understandably, the longer pulse rise time would result in the lower ion impact energy, and less sheath expanding extent. By comparing the sheath structure under different pulse rise time, we found that long pulse rise time would enhance the conformation of the sheath to the target at the earlier stage of the pulse and would reduce the tendency of the ion depletion in the plasma sheath. Accordingly increase the ion impact current at the later stage of the pulse, which is quite important for the PBII process, when the ions have been accelerated adequately.     

早稻田大学皮秒脉冲辐解装置

A compact pulse radiolysis apparatus using a BNL-type s-band photocathode RF gun is now under development at Waseda University. The laser pulse is used for excitation of the photocathode and for generation of white light, which is used for analyzing light in the pulse radiolysis.The system design is shown in Fig. 1. For absorption spectroscopy with wide wavelength region, the white-light continuum was used as analyzing light. The white light continuum was generated by focusing the high intense IR laser into the water cell. The available wavelength was 400-950 nm. Typical data obtained is shown in Fig.2 by using the system. We have performed a deconvolution technique to know the time resolution of our system. For this purpose, we have assumed the shapes of the electron pulse and the laser pulse as Gaussian distributions. Furthermore, the difference of velocity in a sample cell between the electron pulse and the laser pulse due to the refractive index of a sample was also taken into consideration and assuming that the hydrated electrons are formed as a step function and the response function is Gaussian.Thus, time resolution of the system was estimated by deconvolution of the experimental data.We have achieved a time resolution of about 26ps by measuring time profile of hydrated electrons in H2O.