包覆工艺对微球形燃料相弥散燃料混合均匀性的影响

针对微球形燃料相颗粒与基体粉末的流动性相差较大、难于混合均匀,建立了一种微球的包覆工艺,并研究了包覆工艺对混合均匀性的影响。采用直径约为100μm的不锈钢微球代替燃料微球,研究结果表明,在微球表面物理包覆一层基体粉末,可增加颗粒表面粗糙度,降低两组元粉末的密度差及颗粒沉降的距离,包覆层还能使颗粒间保持一定的间距,微观上形成连续的基体网络,减少甚至避免发生偏聚,有效地改善了混合均匀性。包覆工艺的最佳参数为:保温温度,76℃;保温时间,6min;黏结剂添加量,1%;粉末粒径,小于25μm。该方法可用于改善(U-Mo)-Al、(U-Mo)-Zr等微球形燃料相弥散燃料的混合均匀性。     

一种适于湿热环境的防氡涂层

利用自制的防氡涂料,在释氡模块氡提供的辐射环境下,对防氡涂层的防氡性能和防氡稳定性进行了研究。结果表明：在1^#释氡模块氡辐射环境下,涂覆0.8 mm厚的防氡涂层,消泡剂的较佳添加量为0.3%（质量分数,下同）。在消泡剂添加量为0.3%时,随着涂覆厚度的增加,防氡效率提高,当涂覆厚度大于2.0 mm后,防氡效率趋于稳定。在分别添加灰钙、白水泥、石膏和沉淀硫酸钡4种快干助剂的防氡涂层中,仅添加沉淀硫酸钡的防氡涂层的防氡效率明显下降,而添加其他3种快干助剂对防氡涂层的防氡效率基本无影响。在防氡稳定性中,白水泥和石膏的加入在一定程度上降低了防氡涂层的防氡稳定性,而添加灰钙对防氡涂层的防氡稳定性几乎无影响。在湿热和2^#释氡模块氡辐射环境下,防氡涂层仍具有良好的耐湿热老化和防氡性能。     

A Fusion Development Facility Based on the Spherical Torus

The Fusion community could soon have available an opportunity to significantly advance fusion development, an opportunity afforded by the potential of the spherical torus as a plasma confinement system. That opportunity is, in a single device at an affordable price and at a suitable site, to move sequentially through the major fusion objectives of advanced confinement physics, burning plasma and DT physics, blanket and other fusion nuclear technology development, tritium self-sufficiency, and, perhaps at the end with an upside performance outcome, a chance at net electric breakeven. Meeting this set of objectives would dramatically advance the development of fusion.     

球几何单速输运方程的一种变分解

对于球几何问题 ,讨论了一种基于微分方程的变分形式求解方法 ,数值计算显示达到了较满意的精度 ,而且计算过程比起其他近似方法要简单些     

Initial Plasma Startup Test on SUNIST Spherical Tokamak

The goal of the Sino-United Spherical Tokamak (SUNIST) at Tsinghua University is to extend the understanding of toroidal plasma physics at a low aspect ratio (R/a ≈ 1.3) and to demonstrate a maintainable target plasma by non-inductive startup. The SUNIST device isdesigned to operate with up to 13 kA of ohmic heating field current, and to 0.15 T of toroidal field at 10 kA of discharge current. All of the poloidal fields can provide 30 mVs of Volt-seconds transformer. Experimental results of plasma startup show that SUNIST has remarkable characteristics of high ramp rate (dIp/dt ≈ 50 MA/s ), high normalized current IN of about 2.8 (IN = Ip/αBT)，and high-efficiency (Ip/IROD ≈ 0.4) production of plasma current while operating at a low toroidal field. Major disruption phenomena have not been observed from magnetic diagnostics of all testing shots. Initial discharges with 52 kA of plasma current (exceeding the designed value of 50 kA),2 ms of pulse length and 50 MA/s of ramp rate have been achieved easily with pre-ionized filament.     

带热浸铝涂层MANET Ⅱ马氏体钢的氢渗透性能研究

在300～450℃温度范围内,分别在氢气相和液态铅锂合金相中,开展了带热浸铝涂层MANET Ⅱ马氏体钢的氢渗透性能研究.结果表明,实验所得到的氢渗透率减低因子(PRF),在气相中为620～263,在液态铅锂合金相中为45～30.但仍然没有满足DEMO聚变堆的设计要求.涂层的自修复效应在400 ℃以上是明显和有效的.从渗透通量与样品上游氢压的关系来看,涂层使得表面效应对渗透过程的影响很大.在上游小流量及在液态铅锂合金中鼓泡充氢可以导致渗透通量升高.扫描电镜和能谱分析(SEM-EDS)的结果表明,样品表面被液态铅锂合金所浸润的部分出现微裂纹,而未浸润部分没有出现微裂纹.微裂纹很肤浅,仅仅影响涂层的最外表面薄层,没有贯穿整个渗铝层而到达基体.未浸润表面的Al/O原子比约为2/3,浸润表面约为1/1,表明液态铅锂合金对渗铝层表面的Al2O3薄层造成了损伤.总的看来,造成氢渗透阻挡层性能退化的原因,是涂层外表面与液态铅锂合金相互作用,以及涂层在升、降温过程中产生热应力释放.     

The Gridless Plasma Ion Source （GIS） for Plasma Ion Assisted Optical Coating

High-quality optical coating is a key technology for modern optics. Ion-assisted deposition technology was used to improve the vaporized coating in 1980's. The GIS (gridless ion source), which is an advanced plasma source for producing a high-quality optical coating in large area, can produce a large area uniformity＞1000 mm(diameter), a high ion current density ～ 0.5mA/cm2, 20 eV ～ 200 eV energetic plasma ions and can activate reactive gas and film atoms. Now we have developed a GIS system. The GIS and the plasma ion-assisted deposition technology are investigated to achieve a high-quality optical coating. The GIS is a high power and high current source with a power of I kW ～ 7.5 kW, a current of 10 A ～ 70 A and an ion density of 200μA/cm2 ～ 500μA/cm2. Because of the special magnetic structure, the plasma-ion extraction efficiency has been improved to obtain a maximum ion density of 500μA/cm2 in the medium power (～ 4 kW) level. The GIS applied is of a special cathode structure, so that the GIS operation can be maintained under a rather low power and the lifetime of cathode will be extended. The GIS has been installed in the LPSX-1200 type box coating system. The coated TiO2, SiO2 films such as antireflective films with the system have the same performance reported by Leybold Co, 1992, along with a controllable refractive index and film structure.     

聚变-裂变混合能源堆球模型参数敏感性分析

在聚变-裂变混合能源堆球模型基础上,使用蒙特卡罗方法中子学程序对中子源、铀水体积比、产氚区等相关参数进行了中子学的敏感性计算。分析了各参数对混合能源堆能量放大倍数M和氚增殖比TBR的影响,并总结其基本规律,为开展进一步的混合能源堆概念设计提供了重要参考。     

Core Plasma Characteristics of a Spherical Tokamak D-3He Fusion Reactor

The magnetic fusion reactor using the advanced D-^3He fuels has the advantage of much less-neutron productions so that the consequent damages to the first wall are less serious. If the establishment of this kind of reactor becomes realistic, the exploration of 3^He on the moon will be largely motivated. Based on recent progresses in the spherical torus (ST) research, we have physically designed a D-^3He fusion reactor using the extrapolated results from the ST experiments and also the present-day tokamak scaling. It is found that the reactor size significantly depends on the wall reflection coefficient of the synchrotron radiation and of the impurity contaminations. The secondary reaction between D-D that promptly leads to the D-T reaction producing 14 MeV neutrons is also estimated. Comparison of this D-^3He ST reactor with the D-T reactor is made.     

聚变-裂变混合能源堆球模型中子学对算研究

利用蒙特卡罗程序和自主开发的蒙特卡罗-燃耗耦合程序MOCouple-s,对北京应用物理与计算数学研究所提出的聚变-裂变混合能源堆球模型进行了对算研究。对初始时刻及各燃耗时刻下的有效增殖因数、能量倍增因子、氚增殖比、中子源强度等堆芯参数进行了比较,结果总体符合较好。对寿期末重要核素的成分进行了详细比较,除个别核素外,偏差很小,表明所采用的计算程序与核参数库一致性良好。对核参数库的选择、铀水体积比等对燃耗计算结果的影响进行敏感性分析,并对外中子源驱动的次临界堆芯的燃耗计算进行详细讨论,提出可行的燃耗计算基准。     

螺线管透镜像差导致的束流发射度增长研究

螺线管透镜常作为低能束流的聚焦元件,不可避免地具有像差,导致束流发射度增长,降低束流传输效率。本文通过理论推导和计算机模拟,给出了不同束流包络、不同磁感应强度和不同磁场形状的情况下束流经过实际透镜后的发射度增长。结果表明,发射度增长主要与束流包络和磁感应强度有关。但在一定范围内,优化磁场形状也能起到控制发射度增长的作用。     

对CANDU燃料组件结构的一维瞬态辐射程序开发与验证

在气冷CANDU式燃料组件之中,辐射换热也是不容忽视的一部分。特别是在出现了系统失压/失流事故时,辐射换热将会成为保证燃料安全的主要冷却手段。本文中针对CANDU式压力管编制了针对压力管几何条件下的一维辐射换热瞬态程序。程序中采用将燃料元件棒转化为同心圆环的方式简化辐射角的计算,并加入了隔层辐射模型,使模型更加贴近实际。采用分别将程序中的几个模块的计算结果与CFX计算结果对比的方式来达到程序验证的目的,验证结果显示程序RHTPB具有良好的表现,能够满足于反应堆安全计算的需要。     

辐射条件下球腔冷冻靶温度场分布数值研究

惯性约束聚变冷冻靶系统中,为成功实现靶丸点火,冰层厚度均匀性需达到99%,表面粗糙度的均方根要小于1 μm。控制靶丸表面最大温差小于0.1 mK能满足以上点火要求。为研究辐射对惯性约束聚变间接驱动靶丸的温度场影响,建立了三维对称球腔冷冻靶系统的计算模型。考虑球腔内部激光入射口封口膜吸收率以及外部辐射温度对球腔内部温度场分布的影响,利用FLUENT软件对球腔冷冻靶温度场进行了数值模拟计算。研究表明：球腔由于自身具有的球对称几何结构,其内部的温度场分布更加均匀;受外界辐射影响,有窗侧靶丸表面温度较无窗侧温度高;辐射温度越高,靶丸表面的绝对温度越高,虽然靶丸表面的温差变化基本可忽略,但要防止由于外界辐射温度过高而导致的DT冰层均匀性恶化,应选用多层屏蔽罩结构降低辐射的影响;激光入射口封口膜吸收率大于0.2时,靶丸表面温差显著增大。     

Coupling Effect between Equilibrium Field and Heating Field and Modification of the Power Supply System on SUNIST Spherical Tokamak

Strong inductive coupling between the heating field and equilibrium field is confirmed to be responsible for the poor plasma equilibrium in initial discharges on the SUNIST spherical tokamak. A modification project for the power supply system of equilibrium field coils is successfully performed to increase the duration time of plasma current flattop from nmch less than 1ms to about 2 ms.     

锆合金包壳水侧SiC涂层研究

研究了聚碳硅烷（PCS）粉末的高温裂解特性及PCS粉末与锆粉间的化学反应机理,并在900 ℃制备了SiC涂层。研究发现,900 ℃开始,PCS裂解产物由无定形态SiC向结晶态转变。不同温度下,PCS粉末与锆粉的混合物发生一系列化学反应,产物为ZrC、Zr₂Si、Si₃Zr₅,通过调节反应温度,可控制该化学反应的程度,进而实现对涂层成分的调节。采用先驱体转化法（PIP）在锆合金包壳表面制备了SiC涂层,经PCS溶液浸涂-裂解3次循环可得到SiC陶瓷层,厚度为4 μm,涂层成分为SiC,ZrC为过渡层。划痕法测试得到涂层附着力等级为1～2级。     

Solving the Stand-off Problem for Magnetized Target Fusion: Plasma Streams as Disposable Electrodes, Together with a Local Spherical Blanket

In a fusion reactor based on the magnetized target fusion approach, the permanent power supply has to deliver currents up to a few mega-amperes to the target dropped into the reaction chamber. All the structures situated around the target will be destroyed after every pulse and have to be replaced at a frequency of 1–10 Hz. In this paper, an approach based on the use of spherical blanket surrounding the target, and pulsed plasma electrodes connecting the target to the power supply, is discussed. A brief analysis of the processes associated with creation of plasma electrodes is presented.     

添加剂对高温硫化硅橡胶耐辐射性能的影响

研究了五种不同的芳香族添加剂（联苯、萘、菲、二苯甲酮、二苯乙炔）对高温硫化硅橡胶的耐辐射性能的影响。分析了在真空下经受400kGy和600kGy的γ射线辐照下,两交联点间有效链平均分子量Mc和力学性能的变化。讨论了芳香族添加剂的辐射保护机理。结果表明芳香族添加剂,尤其是二苯乙炔,能提高硅橡胶的耐辐射性能。     

铀表面纳米铌镀层的组织结构与界面特性

采用磁控溅射离子镀技术在贫铀表面以不同偏压制备了铌镀层,利用X射线衍射仪和扫描电镜对镀层的组织结构进行了表征,利用扫描电镜与俄歇电子能谱仪对镀层与基体的界面特性进行了研究。结果表明：铌镀层平整致密,但存在靶材飞溅颗粒形成的镀层缺陷,铌镀层为体心立方结构,存在择优取向、内应力以及晶粒细化等特性且为纳米镀层;铌镀层沿基体表面的法线方向生长且为典型的柱状结构,其表面为均匀的条状颗粒组织;铌镀层与铀基体结合紧密,且存在“伪扩散层”。     

等离子喷涂Fe-Ni-B屏蔽涂层的结构与性能研究

采用大气等离子喷涂技术在1Cr18Ni9Ti钢基体上制备了Fe-Ni-B涂层,并对涂层进行了重熔处理.采用扫描电子显微镜(SEM)、X射线荧光光谱仪(EDX)对重熔前后涂层的显微组织及界面结构进行了微观分析,并对重熔前后涂层的显微硬度、热疲劳性能、结合强度进行了试验研究.结果表明,重熔处理对涂层显微结构有明显改善,涂层更为致密.涂层与基体界面处已发生相互扩散并有新相生成,涂层热疲劳性能更好,结合强度也有所提高.     

Mechanical Properties and Uniformity of Nanocrystalline Diamond Coating Deposited Around a Sphere by MPCVD

Nanocrystalline diamond coatings were deposited by MPCVD on the spheres used for a ball bearing.The nanocrystalline coatings with a grain size of 50 nm were confirmed by the surface morphology and composition analysis.The hardness of the coating is 20-40 GPa tested by nanoindentation,which is higher than that of tungsten carbide and silicon nitride substrates.The coating around the sphere observed from the Micro CT images is uniform with a thickness of12 μm.