稠密等离子体聚焦装置的中子产额及其稳定性研究

叙述了稠密等离子体聚焦装置(DPF)作为中子发生器的工作原理,讨论了影响DPF中子产额及其稳定性的一些因素和改进措施。利用不同电极形状、不同绝缘气体的场崎变开关可以很好地提高聚焦装置的运行性能,使装置输出中子的起伏由过去的约两个量级降到目前的3倍左右。通过对腔内电极的清洁,在不更换气体的条件下。中子产额无明显下降。     

用于DPF装置中子测量的闪烁体探测器

介绍了一种用于等离子体焦点装置(DPF装置)中子波形测量的塑料闪烁体探测器,该探测器由ST401型塑料闪烁体、XP2262B型光电倍增管构成。利用银活化中子探测器和DPF装置对该塑料闪烁体探测器进行标定,确定其中子灵敏度为0.022 5 pC每中子,,中子产额测量范围达到109～1011每脉冲,可以满足DPF装置中子参数测量的需要。     

用于DPF装置中子测量的闪烁体探测器

 介绍了一种用于等离子体焦点装置(DPF装置)中子波形测量的塑料闪烁体探测器,该探测器由ST401型塑料闪烁体、XP2262B型光电倍增管构成。利用银活化中子探测器和DPF装置对该塑料闪烁体探测器进行标定,确定其中子灵敏度为0.022 5 pC每中子,,中子产额测量范围达到10⁹～10¹¹每脉冲,可以满足DPF装置中子参数测量的需要。     

利用Si–PIN探测器测量DPF装置中子产额

介绍了Si-PIN中子探测器的结构和测量原理,分析了探测器对14MeV中子的灵敏度.利用该探测器测量了等离子焦点装置的D-T脉冲中子产额,实验结果与SDIN500探测器测量结果在5?%不确定度范围内一致     

等离子体焦点装置径向运动电流壳层的不稳定现象

在ＤＰＦ－４０等离子体焦点装置中，首次观测到径向运动电流壳层的一种不稳定现象，即不稳定模式。它属于ｍ＝０模的ＭＨＤ不稳定性，但仅具有半个波长并且发生在等离子体－电极边界上。在相继的一系列放电中，该不稳定模式五通常的稳定模式以随机方式发生。两种模式对壳层和箍缩等离子体的位形结构和运动方式及中子产额等具有显著的影响。     

稠密等离子体焦点装置研制

研制了一台用作脉冲中子源的稠密等离子体焦点装置(DPF),其放电室为Mather型结构。介绍了整个装置的工作原理及系统组成,详细论述了放电室的设计方法。实验结果表明,在550~600 Pa充氘压力范围下,当储能电容充电电压大于19 kV时,装置的平均中子产额大于5.0×10⁸(D-D)中子/脉冲,中子脉冲宽度(FWHM)为(40±5) ns。该装置能用于中子、伽马辐射诊断中探测系统灵敏度实验研究,也可用于开展快中子照相、中子活化分析以及单粒子效应等方面的研究工作。     

用于等离子体焦点装置的强流装置

研制了用于稠密等离子体焦点的强流装置,该装置采用八台低电感低内阻脉冲电容器和八个低感大电流、可控触发高压开关并联组成初级储能模块,高压开关同步击穿后产生μs级强电流经平行板传输线加载到负载。脉冲电容器和高压开关采用一体化设计,结构紧凑,使脉冲电容器与高压开关间的连接电感尽可能小;平板传输线为扇形结构,一个扇形平板传输线连接一个高压开关,平行板传输线可以将电感做得较小,有利于大电流回路的传输。在脉冲电容器充电20 kV时,假负载上可以得到500 kA的电流,电流上升时间约为3.7 μs。     

双真空烘烤排气台的研制及应用

分析了放电管稳定试验前的烘烤排气对等离子体焦点装置试验结果的影响,介绍了双真空烘烤排气台的原理和结构设计,并利用试验数据说明了该排气台在等离子体焦点装置试验中的重要性,在实际应用中具有潜在的实用价值。     

双真空烘烤排气台的研制及应用

 分析了放电管稳定试验前的烘烤排气对等离子体焦点装置试验结果的影响，介绍了双真空烘烤排气台的原理和结构设计，并利用试验数据说明了该排气台在等离子体焦点装置试验中的重要性，在实际应用中具有潜在的实用价值。     

Z加速器上产生了聚变中子

 美国圣地亚国家实验室的Z加速器上生成的热密等离子体产生了热核中子。圣地亚的研究者今年4月在费城召开的美国物理学会年会的新闻发布会上宣布了这一消息。Z加速器是世界上功率最大、效率最高的实验室X射线源,于1996年9月开始运行。这台加速器包括36台同时驱动的脉冲功率装置。脉冲持续期小于一亿分之一秒。在这样短的瞬间,Z加速器可以产生X射线的功率为290万亿瓦,能量达到190万焦耳。这台加速器主要用于国防上的武器研究以及聚变能的研究。聚变能是宇宙中最普遍的能源。太阳能及氢弹释放的能量都源自原子核的聚变反应。     

Z-pinch中PF腔中子发射的产生机制

采用束 靶机制和热核机制,利用Maxwell分布,推导了等离子体焦点装置的中子产生机制、热核反应速率、中子平均能量及中子反映速率.Using the machanism of beam target and heat nuclics, the scaling relationship between the neutron yields of denser plasma focus and the PF plasma current is induced.The results of DPF .The principle is brief discussed with denser plasma focus(DPF) as the neutron generator.We have stated that some factors that influnce the DPF discharging to produce neutron yield and some methodsthat improve stability of neutron yields on the denser plasma focus(DPF).     

Application of a Double－Wollaston－prism Laser Differential Interferometer in Plasma Focus

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Experimental study of the neutron emission mechanisms in a Filippov-type plasma focus device

The results of an experimental investigation of neutron emission characteristics in the Filippov-type plasma focus facility Dena (90 kJ, 25 kV, 288 µF) with D₂ + %1 Kr as working gas are presented. From the experimental results, one can conclude that both thermonuclear and nonthermonuclear mechanisms are always present in neutron production, but their contributions to the total neutron yield are strongly dependent on the initial pressure and discharge voltage. It has been found that at constant discharge voltages and low pressures the beam—target interaction mechanism plays an important role in the neutron production and with increasing the pressure, its role decreases and the importance of thermonuclear mechanism increases. Also at constant pressures, the contribution of beam—target interaction mechanism in neutron production decreases with increasing the discharge energy. The value of the index in the empirical neutron yield scaling law Y_n I E^/2 was found to be about 3.82.     

基于D-T紧凑型中子源的快中子照相准直屏蔽体设计及中子束特性模拟研究

中子照相是一种重要的无损检测技术,它能用于火工产品、毒品和核燃料元件等的检测。基于紧凑型D-T中子发生器,完成了一个用于快中子照相的准直屏蔽体系统（BSA）的物理设计。根据D-T中子源的能谱和角分布建立了中子源模型,采用MCNP4C蒙特卡罗程序,模拟了准直屏蔽体系统中中子和γ射线的输运,准直中子束相对于单位源中子的中子注量可以达到9.30×10-6 cm-2,准直中子束中主要是能量大于10 MeV的快中子;在设置的样品平面直径14 cm的照射视野范围,准直束中子注量的不均匀度为4.30%,准直束中中子注量与γ注量的比值为17.20,中子通量和中子注量比值J/Φ为0.992,说明准直中子束有好的平行性;准直屏蔽体外的泄露中子注量率与准直束中子注量率相比降低了2个量级。所设计的准直屏蔽体能满足快中子照相的要求。Neutron radiography is an important nondestructive testing technique. It can be used to detect the explosive devices, drug and the nuclear fuel element, etc. A beam-shaping-assembly (BSA) based on a compact D-T neutron generator is designed for fast neutron radiography in this paper. D-T neutron source model is constructed based on the neutron energy spectrum and angular distribution data. The transportation of neutron and γ-ray in the BSA is simulated using MCNP4C code. The neutron fluence of the collimated neutron beam with respect to the neutron source of the unit source is 9.30×10-6 cm-2. The collimated neutron beams is mainly fast neutrons with energies greater than 10 MeV. In the irradiation field range with a diameter of 14 cm, the neutron fluence uniformity of the collimated beam is 4.3%, the ratio of the neutron fluence to the gamma fluence in the collimated beam is 17.20, and the neutron flux and the neutron fluence ratio (J/Φ) is 0.992 which indicates that the collimated neutron beam has good parallelism. The leakage neutron fluence in outside of BSA is two orders of magnitude lower than that of the collimated neutron beam. The designed BSA can meet the need of fast neutron radiography.     

PGNAA系统中D-T中子管的慢化装置优化设计

为了提高PGNAA系统中D-T中子管的中子慢化效率,获得更高的热中子产额,借助蒙特卡罗模拟,确定了以铅为中子反射层、5个聚乙烯层和铅层相互交替作为中子慢化层、碳化硼含量为3%的含硼聚乙烯作为中子吸收层以及铅作为γ屏蔽层的中子慢化装置模型。针对中子产额为3×107 n/s 的D-T中子管,该慢化装置输出面低于5 eV中子通量可达5.28×106 n/s,占总中子通量的30.8%,有效提高了中子慢化效率。经过验证模拟结果能够满足实验要求。To improve the moderating efficiency of D-T Neutron Generator in PGNAA system, and get higher thermal neutron yield, the Monte Carlo code MCNP was used to optimize the moderation setup. The lead was selected as neutron reflector and gamma absorber, 5 polyethylene layers and 4 lead layers constituted the neutron moderator and 3% boron-doping polyethylene was selected as neutron absorber. For the yield of 3107 n/s D-T Neutron Generator, this moderation setup can provide a yield of lower than 5 eV of 5.28106 n/s, accounting for 30.8% of total neutron yield, dramatically improves the moderating efficiency. It is proved that the simulation results can satisfy the requirement of PGNAA system by preliminary experimental verification.     

厚靶D（d,n）^3He反应加速器中子源的产额、能谱和角分布

给出一种计算氘钛厚靶D(d,n)3He反应加速器中子源的产额、能谱和角分布的方法,并发展了一个计算机模拟程序,程序能够计算氘束流能量小于1.0 MeV的中子源的产额、能谱和角分布.计算时使用推荐的D(d,n)3He反应截面数据和来自SRIM-2003程序的氘在氘钛靶中的阻止本领数据.给出一些典型计算结果,包括中子积分产额、中子能谱和角分布.     

An Innovative Simple Method for Study of the Characteristics of the Trigatron Plasma Switch

A simple Semi‐Analytical method used to fit the experimentally recorded current of the closed switch discharge circuit into the free running under damped LC oscillator model and the arc plasma conductivity, electron density of the plasma and efficiency of the spark gap switch energy transfer have been driven from the model by some simple calculations. The charging voltage, switch pressure and the spark gap has been changed between 6 to 15 kV, 1 to 1.5 bar and 1.4 or 2.8 mm, respectively. The obtained values for plasma conductivity and electron density of plasma are (5‐25)(Ω mm)^–1, (0.5–3.5)·10²⁴m^–3, respectively. The efficiency of the switch is plotted Vs. Pd and E/P which in both cases the peak value has been about 80 present.