Enhancement of neutron irradiation uniformity for the CFBR-Ⅱ fast burst reactor with a biaxial rotational technique

A biaxial rotational technique is proposed to improve the neutron irradiation uniformity for a large sample,and the theoretical method is established to predict and design the main parameters. The technique used a device to rotate the target sample around two perpendicular axes simultaneously. Numerical calculations found that the lowest common multiple of the two angular speeds should be large enough to improve the uniformity,and the minimal experimental time should be no less than 600 s. For a three-dimensional sample with a size of 20 cm × 12 cm × 14 cm, the maximal non-uniform neutron irradiation factor of the sample is mainly determined by the distance between the center of the sample and of the point neutron source. It was computed to be less than 10% when the distance was no less than 34 cm. Experiments were carried out on the CFBR-II reactor and the experimental results were in good accordance with the theoretical analysis. As a result, the theoretical conclusions given above are reasonable and of reference value for the design of future irradiation experiments.

Non-Uniformity of Heavy-Ion Beam Irradiation on a Direct-Driven Pellet in Inertial Confinement Fusion

Heavy-ion-driven fusion （HIF） is a scheme to achieve inertial confinement fusion （ICF）. Investigation of the non-uniformity of heavy-ion beam （HIB） irradiation is one of the key issues for ICF driven by powerful heavy-ion beams. Ions in HIB impinge on the pellet surface and deposit their energy in a relatively deep and wide area. Therefore, the non-uniformity of HIB irradiation should be evaluated in the volume of the deposition area in the absorber layer. By using the OK1 code with some corrections, the non-uniformity of heavy-ion beam irradiation for the different ion beams on two kinds of targets were evaluated in 12-beam, 20-beam, 60-beam and 120-beam irradiation schemes. The root-mean-square （RMS） non-uniformity value becomes aRMS = 8.39% in an aluminum mono-layer pellet structure and aRMS = 6.53% in a lead-aluminum layer target for the 12-uranium-beam system. The RMS non-uniformity for the lead-aluminum layer target was lower than that for the mono-layer target. The RMS and peak-to-valley （PTV） non-uniformities are reduced with the increase in beam number, and low at the Bragg peak layer.

Polarization visualization for low-irradiance regions by perceptually uniform color space

Currently,polarization visualization strategies are accomplished by mapping polarization information into a perceptually uniform color appearance model CAM02-UCS.However,the deviation of the CAM02-UCS space from the lightness prediction results in an inaccurate match between the polarization information and the perceptual information.In this paper,we propose a novel polarization visualization strategy based on the perceptual uniform space Jzazbz.The polarization visualization be completed by placing the polarization information into the lightness Jz,colorfulness Cz and hue angle hz channels of the Jzazbz space.The experimental results show that the proposed method can significantly improve the lightness of the low irradiance and high polarization region,hence more polarization information can be sensed by human visual system.

Layered Ag-graphene films synthesized by Gamma ray irradiation for stable lithium metal ano des in carb on ate-based electrolytes

Lithium metal batteries are considered as high energy density battery systems with very promising prospects and have bee n widely studied.However,The uncon trollable plating/strippi ng behavior,infinite volume change and den drites formation of lithium metal anode restrict the applicati on.The unc on trolled n ucleati on of lithium caused by the non uniform multi-physical field distributions,can lead to the undesirable lithium deposition.Herein,a graphene composite uniformly loaded with Ag nano-particles(Ag NPs)is prepared through a facile Gamma ray irradiation method and assembled into self-supported film with layered structure(Ag-rGO film).Whe n such film is used as a lithium metal an ode host,the uncontrolled deposition is converted into a highly nucleation-induced process.On one hand,the Ag NPs distributed between the in terlayers of graphe ne can preferentially induce lithium nu cleati on and en able uniform deposition morphology of lithium between interlayers.On the other hand,the stable layered graphene structure can accommodate volume change,stabilize the interface between anode and electrolyte and inhibit dendrites formation.Therefore,the layered Ag-rGO film as anode host can reach a high Coulombic efficiency over 93.3% for 200 cycle(786 h)at a current density of 1 mA cm^(-2) for 2 mAh cm^(-2) in carbonate-based electrolyte.This work proposes a facile Gamma ray irradiation method to prepare metal/3D-skeleton structure as lithium anode host and demonstrates the potential to regulate the lithium metal deposition behaviors via manipulating the distribution of lithiophilic metal(e.g.Ag)in 3D frameworks.This may offer a practicable thinking for the subsequent design of the lithium metal anode.

双自由曲面光束整形系统的虚拟面迭代设计法

双自由曲面光束整形系统可在不改变光束相位分布的情况下实现光束空间光强分布的按需调控,然而其需要设置虚拟平面来进行双自由曲面面形的求解。研究发现,传统单一虚拟面法在应用于结构紧凑和扩束倍率较大的系统时,存在设计不精准、整形效果差等缺陷,为此,提出了一种基于虚拟面迭代策略的双自由曲面光束整形系统设计方法。基于不同参数的同轴透射式和离轴反射式光束整形系统的数值仿真研究结果,表明该方法可有效规避传统虚拟面法的局限性。以将束腰半径为5 mm的高斯光束整形为半径30 mm的准直平顶光束的透射式双自由曲面光束整形系统为例,虚拟面迭代法所设计的光束整形系统将光强分布均匀性和能量利用率相对于单一虚拟面法而言分别提升了2.93%和8.93%。

双源X射线辐照仪电气控制系统研究

作者及所属团队发明的一种双源X射线辐照仪提高自屏蔽X射线辐照仪的产能,但是新型的结构和更大的辐射剂量给环境剂量安全带来更大的挑战。为了确保人员不会被电离辐射所伤,除了通过辐射防护屏蔽设计达到自屏蔽效果,还需要很多安全联锁的检测元件和电气结构设计来检测和避免各种意外。另外为了确保辐照剂量的准确和均匀,也需要很多电气设备及检测元件。该文通过对双源X射线辐照仪设备的结构原理,以及相关人员、环境和使用方法等因素的深入探索和分析,进一步揭示这些因素对双源X射线辐照仪的安全性和可靠性的关键影响。基于此,该文进行双源X射线辐照仪的电气系统及控制程序的研究与设计。通过对双源X射线辐照仪的安全性和可靠性的测试,得到电气系统和控制程序在实际应用中的表现的有效验证。

高功率高均匀性稳态硬X射线辐照装置研制

X射线辐照广泛应用于农业育种、材料改性、器械消毒和电子设备抗核加固设计等诸多领域。本文介绍了一种高功率、高剂量均匀性的紧凑型硬X射线辐照源的研制,针对辐照的剂量率、空间均匀性、能谱等需求,通过蒙特卡罗模拟方法进行优化设计,结合长期运行可靠性对电源的要求等,采用了“三明治”型结构X射线输出窗,工作电压为225 kV,总功率为9 kW。研制的样机经过测试,在距离靶点150~200 cm的Φ500 mm辐照空间内剂量率不均匀度优于3 dB,平均剂量率最大约39.72 Gy/h,X射线能谱的平均能量约为59.88 keV。该辐照源已经在电子设备抗核加固设计、病毒辐照效应等领域得到应用。

基于均匀化激光双面辐照的热力耦合测试方法研究

为了研究以激光为热源开展材料高温力学性能测试的可行性,建立理论模型与数值模型,分析了材料在双面均匀激光光斑加热下的表面及内部温升。结果表明,理想情况下采用均匀化激光双面辐照的加热方式可以在试件加热区域内形成较均匀的温度场。为验证上述结论,建立了光斑匀化度达92%的激光双面辐照热力耦合测试试验平台,并基于相关测试方法获取了传统加热方式难以快速加热的CFRP层合板高温拉伸强度。结果表明,试件在激光加热中心测试区域(10 mm×10 mm)内的温度均匀性良好。试件在均匀化激光双面辐照下可被快速加热至923℃,测试区域内的最大温度波动为6.8%。文中提出的基于均匀化激光双面辐照的热力耦合测试方法相比传统测试方法具有通用性好、温升率高、测试温度高、测试效率高等一系列的优点。该研究可为进一步研制通用型材料/结构高温升率、高温力学性能试验系统提供关键技术支撑。

光学积分器离焦与散热结构设计

光学积分器是太阳模拟器核心匀光部件,通过适当离焦可提高辐照均匀性。针对目前光学积分器离焦精度低、装调困难、散热效率不高等不足,提出一种高温工况下能够连续离焦和有效散热的光学积分器机械结构。通过离焦分析确定投影镜组离焦范围,设计一种由螺旋传动和直线导槽组成的连续离焦结构及环形肋片的散热结构,并在热载荷下对结构参数进行有限元分析与优化。通过实际测试,光学积分器离焦-2.6 mm时,Φ100 mm辐照光斑内的辐照不均匀度±0.44%,太阳模拟器辐照均匀性最佳,表明投影镜组在高温下能够连续离焦调整,有效提高光学积分器装调精度和效率。

基于5kW非共轴聚光型模拟器性能数值研究

文章采用Tracepro软件对一个5 kW小型非共轴聚光型太阳能模拟器建立数学模型,通过实验验证了模型的准确性,并计算得到了太阳能模拟器中聚光镜的结构参数(旋转角度θ、后端开口直径、前端开口直径)和氙灯光源的安装误差(光源离焦、偏转角)对太阳能模拟器焦平面热流密度峰值和辐照不均匀度的影响规律。研究结果表明:太阳能模拟器焦平面热流密度峰值与辐照不均匀度随聚光镜旋转角度呈现逐渐下降的趋势;热流密度峰值与辐照不均匀度随聚光镜后端开口直径增加分别呈下降和上升趋势;热流密度峰值与辐照不均匀度随前端开口直径增加分别呈上升和下降趋势;光源离焦对焦平面热流密度峰值有负影响;光源偏转角度对热流密度峰值和辐照不均匀度几乎无影响。文章研究结果对太阳能模拟器聚光镜结构及汇聚光斑性能优化提供了理论指导。

Theoretical analysis of lens array for uniform irradiation on target in multimode fiber lasers

We propose and demonstrate a scheme to smooth and shape the on-target patterns in multimode fiber lasers, which includes expanding-collimating system and lens array （LA）. A smooth pattern with flat-top and sharp-edge profiles can be obtained with the irradiation nonuniformity decreasing significantly. We analyze the effects of the parameters such as defocus distance, the tilt angles, the number of the incident fiber lasers, and the diffraction-weakened LA on the uniformity irradiation of target by numerical simulations.

积分球辐射光源照度均匀性研究

针对CCD等焦面阵列光电器件常被置于积分球辐射光源出口平面进行测试的误区,研究了积分球辐射光源照度分布的均匀性,得到了合理使用积分球光源测试光电器件的依据。基于数值解析方法和蒙特卡罗方法,建立了理想积分球辐射光源照度均匀性数学模型和非理想积分球辐射光源照度均匀性仿真模型,分析了与积分球光源出口不同距离处光电器件受光面上照度分布情况,并实验测试了两套积分球辐射光源照度分布情况,得到了与积分球辐射光源不同距离处光电器件受光面上照度均匀性分布规律。研究表明:当光电器件受光面直径小于积分球光源出口直径一半、光电器件和积分球出口之间的距离与积分球出口直径的比值在3至5之间时,可在光电器件受光面上获得均匀性优于99%的照度场。

10MeV电子直线加速器辐照工艺确定的简便方法及其应用

为简化辐照工艺制定方法,以10Me V电子直线加速器为研究对象,利用铝片叠层法测定电子束单双面辐照时铝片中的剂量分布情况,并以此为基础推算、建立并验证不同密度产品10Me V电子束单双面辐照的深度剂量分布曲线,得出10Me V电子束辐照时各射程深度与材料密度的关系公式。根据深度剂量分布曲线,明确了双面辐照时均一密度产品在不同辐照深度情况下对应的剂量不均匀度(U)。以U≤2.5为标准,将产品按不同厚度分类,建立相应的辐照加工工艺,且实际生产应用效果良好。本研究对10 Me V电子直线加速器辐射加工工艺制定具有一定的指导意义。

^(60)Co辐照装置剂量场均匀性的优化设计

采用蒙特卡罗方法和MATLAB(Matrix Laboratory)程序对由576根钴源构成的辐照装置中剂量场均匀性进行优化设计。首先将程序计算结果与实验测量进行比较,接着对程序设置3200个计算点计算了辐照装置的剂量场分布;剂量场均匀性计算中,不断地改变钴源棒位置并不断计算空间平面剂量场。计算结果发现,程序计算值与实验测量值较为一致,经调整后装置的空间剂量均匀度显著提高,使得辐照装置的能量使用率大大提高。

微波辐照下均分散氧化亚铜超细粒子的制备

在微波辐照条件下 ,用沉淀法制备了氧化亚铜均分散超细粒子 .实验表明 :随加热方式、CuSO4 浓度、表面活性剂或螯合剂的不同 ,粒子的形状呈方形、雪花形、球形多种形态 ,特别是雪花形粒子 ,尚未见文献报道 .与传统加热方式相比 ,微波辐照制备的粒子均分散性更好。

分布式焦点法线聚焦菲涅耳聚光器设计及性能分析

在聚光型光伏系统中,聚光光斑的幅照度不均匀性会降低光伏电池的光电转换效率;并且造成光斑局部点的能量过高,灼伤光伏电池。根据非成像光学理论,介绍了一种基于分布式焦点法设计线聚焦菲涅耳聚光器的方法,并与传统采用共焦法设计的线聚焦菲涅耳聚光器进行了对比分析。结果表明:在保证能量聚光比以及最大能量透过率不变的情况下,使用分布式焦点法设计的菲涅耳聚光器可使聚光光斑的辐照度均匀性得到很大改善,有利于提高光伏电池的光电转换效率,延长光伏电池的使用寿命。

AAA级太阳模拟器的设计与研制

完成了一种光谱匹配、辐照不均匀度和辐照不稳定度均能达到A级标准的AAA级太阳模拟器的设计与研制。介绍了太阳模拟器的光源选择和滤光片的设计,给出了太阳模拟器的光机结构,测量了太阳模拟器的各项技术指标。结果表明,太阳模拟器的光谱匹配在波长400～1 100 nm处满足ASTM E927-10中AM1.5G A级要求。在有效辐照面55 mm×55 mm内,其平均辐照度达到1 000 W/m2,辐照不均匀度达到1.35%,辐照不稳定度达到1.27%。测量数据显示设计的太阳模拟器满足ASTM E927-10的AAA级标准。

具有一个太阳常量的高准直太阳模拟器光学系统设计

为解决现有太阳模拟器无法同时模拟真实太阳张角和真实辐照度（一个太阳常量）的难题,设计了一种新型太阳模拟器光学系统,阐述了光学系统中聚光镜的设计、光学积分器的优化技术及投影镜组的离焦对辐照不均匀度的影响.利用Zemax软件,以序列与非序列功能相结合的方式对积分器的光学参量进行优化,并设计了视场光阑和准直物镜系统.利用LightTools软件对光学系统进行仿真,结果表明：设计的太阳模拟器可以实现32′的真实太阳张角模拟,且辐照度达到一个太阳常量.同时,辐照面小于Φ100mm时,不均匀度优于±1.6%;辐照面在Φ（100～300）mm时,不均匀度优于±3.8%.

兰州重离子加速器细胞辐照装置

介绍了重离子加速器上专门设计的用于动物细胞研究的辐照装置。用聚碳酸酯薄膜蚀刻法研究了该装置的辐照均匀性。

KFTA太阳模拟器辐照均匀性仿真

文章着重介绍了太阳模拟器光学系统及氙灯的建模,尤其对短弧氙灯建模做了详细阐述,它是根据短弧氙灯的亮度分布图采用多个体光源嵌套的形式模拟氙灯,用角度切址文件和光谱分布数据定义短弧氙灯的角度分布和光谱分布。最后运用美国ORA公司的光学分析软件LightTools对太阳模拟器辐照均匀性进行仿真计算,并得到辐照度的一维、二维和三维图形。