西安脉冲堆大空间中子辐照实验平台辐射场参数测量

西安脉冲堆于2010年建成了大空间中子辐照实验平台。本文介绍了该实验平台辐射场设计参数、辐射场测量方法和实测结果。采用蒙特卡罗方法计算了实验平台内中子初始谱。利用多箔活化法测量了中子能谱,解谱方法采用遗传算法,并与SAND-Ⅱ解谱方法进行了对比,对比结果较为一致,证明了遗传算法解谱的有效性。应用热释光剂量计测量了γ射线吸收剂量率。测量结果表明,该实验平台辐射场参数符合设计要求。     

氘离子轰击钼靶的二次电子发射系数测量

设计了一套二次电子测量装置,采用间接测量法,利用中子发生器产生的氘离子束,对氘离子束轰击下钼靶的二次电子发射系数进行了实验研究,获得了钼的二次电子发射系数随不同入射氘离子能量的变化趋势,氘离子束能量为170 keV时的二次电子发射系数最大,约为2.33.     

阵列BF3计数器制作与性能研究

设计和实验研制了用于脉冲中子源中子产额绝对测量的阵列BF3 计数器,并在加速器上进行了DT中子灵敏度标定实验。给出了该计数器测量DT脉冲中子产额的测量结果和测量不确定度,并与其它测量方法的测量结果进行了比较。实验验证了BF3 设计的可行性和DT脉冲中子产额测量数据的可靠性。     

加速器驱动次临界反应堆次临界度测量方法研究

以IAEA ADS基准题和日本京都大学KUCA实验装置为对象,对作者提出的次临界度测量方法[1]进行了更广泛的可行性验证。结果表明:对于局部区域功率变化引起的小扰动,通过改进表征中子注量率空间分布的特征参数,该方法仍然具有高的精度;而对于控制棒插入引起的大扰动,通过引入修正因子的方法,也仍然能准确测量次临界度。     

X射线管焦点尺寸测量方法研究

本文提出了一种焦点尺寸测量方法--锥孔法，其仅需借助射线管上的铅制锥孔，使用平板探测器采集光场图像，然后利用光场边缘射线强度分布可计算得到焦点尺寸。该方法的操作和测试条件简单，实验结果表明，该方法能方便快捷地测量焦点尺寸。     

铅铋堆零功率实验装置控制棒价值测量及方法优化

零功率实验装置的控制棒价值测量一般采用周期法、置换法或落棒法对刻棒实验进行简单处理。为提高刻棒效率，本文提出了无补偿的多步降棒刻棒方法，采用该方法对我国首个铅铋堆零功率实验装置控制棒价值进行了测量，与补偿刻棒方式及落棒法测量结果进行了对比，并通过理论计算验证了该方法的准确性。结果表明：本文方法有效降低了空间效应对测量值的影响，控制棒价值测量结果准确可靠，可在较短时间内完成较高精度的刻棒实验，适用于需经常更换装料方案的临界实验装置。     

中国实验快堆某辐照实验组件燃耗分布测量

在中国实验快堆（CEFR）上建立了实验组件燃耗分布测量的实验装置。对CEFR某一辐照实验组件中的4#及6#燃料元件棒进行了相对燃耗分布的测量，并与理论计算结果进行了比较。结果表明：两根燃料元件棒虽处于实验组件的不同位置，但相对燃耗分布基本一致；燃耗分布的实验测量结果与理论计算结果符合较好；实验组件燃耗分布测量的相对误差在10.2%以内。本文工作为开展快堆乏燃料组件燃耗测量奠定了基础。     

西安脉冲堆实验装置参数测试

反应堆各实验孔道的参数是反应堆的重要指标，也是反应堆应用的重要参数。在简单介绍西安脉冲反应堆参数测量方法、测量设计的基础上，详细给出了该堆上一些实验孔道的参数测试结果，为在该堆的应用工作提供参考。     

热分析法测量中子通量密度的探测器材料选择

热分析法测量中子通量密度是一种新测量方法,它基于热分析技术测量经中子辐照后的探测器材料所放出的退火热量。选择合适的探测器材料是对该方法进行研究的前提,工作的主要内容是根据该测量方法的原理采用多种含10B物质进行实验研究,选出合适的探测器材料。通过对实验结果的对比分析,总结出了热分析法探测器材料需要满足的条件,并初步选定晶体硼与磷灰石的混合物作为热分析法探测器材料,为以后进一步的研究提供参考。     

用热膜测速仪测量水平管内气液泡状流的液相速度和紊流结构

对热膜测速仪应用于气液两相泡状流中的测量方法进行了研究。提出了一套全新的相鉴别技术，用此方法对水平管内的气液两相泡状流的液相速度和紊流强度进行了测量。并对液相水质及温度对测量结果的影响进行了探讨。实验结果表明．在水平管泡状流中．靠管道下部液流速度和紊流强度分布与单相液流的分布差别不大；管道上部较多的气泡使两相液流速度明显低于单相液流速度，增强了紊流强度；使紊流强度分布在r／R=0．5附近有一峰值。     

Validity Analysis of Spatial Distribution Measurement of Secondary Electron by Solving Eigenmatrix Method

In order to measure the secondary electron spatial distribution of different materials in the actual environment accurately, a new type of secondary electron emission spatial distribution measurement structure was designed. The experimental measurement principle was given, and the measured data were analyzed by solving the eigenmatrix method to obtain the required secondary electron spatial distribution. The validity of proposed measurement method by simulation calculation was verified, and the simulation result was consistent with the assumed secondary electron spatial distribution function. It indicates that the measurement method is reliable and accurate. The prototype of measurement system will be developed based on this new design.     

基于多层吸收法的6 MeV电子能谱重建的研究

电子能谱的测量是电子加速器性能检测的重要环节。本文设计了一种新的测量方法--多层吸收法来对电子能谱进行测量,它是基于在辐照电子加速器上应用最多的射程法,加入Monte-Carlo模拟和迭代算法而重建出入射电子能谱的一种方法。该方法具有操作简便、测量准确、无需复杂设备等优点。本文用该方法对6 MeV加速器的电子能谱进行了测量,得到了较好的结果,且与磁谱仪的测量结果在误差范围内符合得很好,验证了其可行性。     

兰州高能电子成像实验平台电子束团长度测量研究

为提高高能电子成像的时间和空间分辨率,实验需低能散、低发射度、短脉冲的高品质束流。本文利用相干渡越辐射能谱分析法测量基于热阴极微波电子枪的高能电子成像用直线加速器的电子束团长度。通过用迈克尔逊干涉仪测量太赫兹辐射能谱,利用自相关曲线拟合法得到电子束团长度。实验结果表明,当束流宏脉冲峰值强度约为24 mA,即电荷量约为15 pC时,电子束团均方根长度约为0723 5 ps。另外,用Kramers Kronig(K K)相位分析法可重建一种可能的电子束团纵向分布。电子束团长度测量的研究可优化束流品质,对后续高能电子成像实验有重要的参考意义。     

Effects of Magnetic Field and Ion Velocity on SPT Plasma Sheath Characteristics

The distribution of magnetic field in Hall thruster channel has significant effect on its discharge process and wall plasma sheath characteristics. By creating physical models for the wall sheath region and adopting two-dimensional particle in cell simulation method, this work aims to investigate the effects of magnitude and direction of magnetic field and ion velocity on the plasma sheath characteristics. The simulation results show that magnetic field magnitudes have small impact on the sheath potential and the secondary electron emission coefficient, magnetic azimuth between the magnetic field direction and the channel radial direction is proportional to the absolute value of the sheath potential, but inversely proportional to the secondary electron emission coefficient. With the increase of the ion incident velocity, secondary electron emission coefficient is enhanced, however, electron density number, sheath potential and radial electric field are decreased. When the boundary condition is determined, with an increase of the sinmlation area radial scale, the sheath potential oscillation is aggravated, and the stability of the sheath is reduced.     

用于HL-2A装置的新型硬X射线探测器

介绍了一种应用于托卡马克等离子诊断领域的新型硬X射线探测器,该探测器主要由硅酸钇镥(Lutetium-yttrium Oxyorthosilicate,LYSO)闪烁体和硅光电倍增管(Silicon Photomultiplier,Si PM)组成。基于项目应用需求,对探测器的选型和基于粒子输运蒙特卡罗仿真软件GEANT4的探测器设计加以阐述,并搭建了前端的探测系统,在HL-2A托卡马克装置上进行了现场诊断实验。实现了硬X射线空间能谱和辐射强度分布的诊断测量。实验表明该探测器阵列具有10 ms的时间分辨率,同时具有结构紧凑、使用方便等特点,能够满足等离子体诊断中硬X射线动态能谱和强度分布测量的诊断需求。     

Recent progress on the J-TEXT three-wave polarimeter-interferometer

The J-TEXT three-wave polarimeter-interferometer system (POLARIS), which measures time-space distribution of electron density and current density, has been optimized with both the optical system and the equilibrium reconstruction method. The phase resolution of a Faraday rotation angle has been improved from 0.1 to 0.06 degree in chords from –0.18 to 0.18 m (plasma minor radius), and the sawtooth oscillation behavior has been detected by Faraday rotation angle measurement. By combining the POLARIS measured data and the equilibrium and fitting code (EFIT), an upgraded equilibrium reconstruction method has been developed, which provides a more accurate temporal and spatial distribution of current density and electron density. By means of the optimized POLARIS and improved equilibrium reconstruction, variations of profiles with increasing density have been carried out, under both Ohmic and electron cyclotron resonance heating discharges.     

New measuring technique for assay of radioactive materials in waste drums

A new measuring technique for determination of radioactive materials and estimate of the source distribution in waste is proposed. The principles of measurement and calculation results are presented.

Based on the mathematical simulation of the gamma ray measurement proposed in this paper with the Segmented Gamma Scanner calculations have been carried out. The calculation results prove that the new technique is much better than the well-known measurement method.     

辐射加工级电子束量热计设计

为设计一种可以用于测量辐射加工级电子束吸收剂量的量热计,采用高纯石墨为吸收体,发泡聚苯乙烯（EPS）为绝热层材料,结合MCNP吸收剂量模拟结果设计各个部分的结构,利用ANSYS模拟分析软件进行热分析,确定各个部分的具体尺寸。以此量热计为基础,在某公司的10 MeV电子加速器下进行实验,采用microK250高精密测温电桥测量电阻阻值,获得10 MeV标称能量下的电子束吸收剂量的测量结果,得到吸收体被照射时间变化与吸收剂量的比例关系。探讨量热计准确性的影响因素,在能量为10 MeV时测量电子束吸收剂量的总不确定度为1.43,本研究结果可为辐射加工级电子束的吸收剂量测量提供参考。     

Study of axial double layer in helicon plasma by optical emission spectroscopy and simple probe

In this work we used a passive measurement method based on a high-impedance electrostatic probe and an optical emission spectroscope (OES) to investigate the characteristics of the double layer (DL) in an argon helicon plasma.The DL can be confirmed by a rapid change in the plasma potential along the axis.The axial potential variation of the passive measurement shows that the DL forms near a region of strong magnetic field gradient when the plasma is operated in wavecoupled mode,and the DL strength increases at higher powers in this experiment.The emission intensity of the argon atom line,which is strongly dependent on the metastable atom concentration,shows a similar spatial distribution to the plasma potential along the axis.The emission intensity of the argon atom line and the argon ion line in the DL suggests the existence of an energetic electron population upstream of the DL.The electron density upstream is much higher than that downstream,which is mainly caused by these energetic electrons.     

基于CADMesh的蒙特卡罗自动建模方法及应用

为开展复杂结构场所辐射场蒙特卡罗模拟研究,使用开源的CADMesh接口程序实现一种将三维CAD数据模型导入Geant4的自动建模方法。对某废物处理设施进行自动建模,使用Geant4内建的基于命令的统计功能计算周围剂量当量率分布。将周围剂量当量率分布模拟结果与实际测量结果进行对比,模拟结果在50%误差范围内与实测数据基本符合,初步验证了该自动建模方法的适用性。