Magnetic field enhanced radio frequency ion source and its application for Siincorporation diamond-like carbon film preparation

Various ion sources are key components to prepare functional coatings,such as diamond-like carbon(DLC)films.In this article,we present our trying of surface modification on basis of Si-incorporation diamond-like carbon(Si-DLC)produced by a magnetic field enhanced radio frequency ion source,which is established to get high density plasma with the help of magnetic field.Under proper deposition process,a contact angle of 111°hydrophobic surface was achieved without any surface patterning,where nanostructure SiC grains appeared within the amorphous microstructure.The surface property was influenced by ion flow parameters as well as the resultant surface microstructure.The magnetic field enhanced radio frequency ion source developed in this paper was useful for protective film applications.     

国外最新消息

美国NRG能源公司将建造更多的核电厂美国NRG能源公司执行总裁David Crane表示,公司将拥有更多的核电厂,包括计划在得克萨斯州建造的两座机组。(编译自路透社2007年11月6日报道)     

《原子能科学技术》征稿简则

须包括题目、作者姓名、作者单位、城市名、省名和邮政编码,并应写成叙述性文摘(含有研究目的、方法、结果和结论);关键词3～8个。3)文稿应采用阿拉伯数字进行分级编号。引言不编号,也不写引言字样。4)基金项目名称及项目编号、作者简介(第1作者姓名(出生年—)、性别(民族,汉族略)、籍贯、职称、学位、从事     

国外最新消息

切尔诺贝利核电机组完成最后一次卸料工作2008年4月23日,切尔诺贝利核电厂完成了其3号机组的最后一次卸料工作。此次卸料工作的完成,意味着切尔诺贝利核电厂已完成了所有的机组卸料工作。(编译自世界核新闻网站2008年4月24日报道)     

国际原子能机构成员国

1957年阿富汗、阿尔巴尼亚、阿根廷、澳大利亚、奥地利、白俄罗斯、巴西、保加利亚、加拿大、古巴、丹麦、多米尼加共和国、埃及、萨尔瓦多、埃塞俄比亚、法国、德国、希腊、危地马拉、海地、罗马教廷、匈牙利、冰岛、印度、印度尼西亚、以色列、意大利、日本、大韩民国、摩纳哥、摩洛哥、缅甸、荷兰、新西兰、挪威、巴基斯坦、巴拉圭、秘鲁、波兰、葡萄牙、罗马尼亚、俄罗斯联邦、塞尔维亚和黑山、南非、西班牙、斯里兰卡、瑞典、瑞士、泰国、突尼斯、土耳其、乌克兰、英国、美国、委内瑞拉、越南1958年比利时、厄瓜多尔、芬兰、伊朗伊斯兰共和国、卢森堡、墨西哥、菲律宾、苏丹     

前言

由中国文物保护技术协会释光与电子自旋共振测定年代专业委员会(挂靠在上海博物馆)和中国国家地震局地质研究所共同主办的全国第十次释光(Luminescence)与电子自旋共振(ESR)测定年代学术讨论会于2006年11月6-10日在杭州的浙江省地震局培训中心召开.来自内地和香港的大学、中国科学院及部委研究所和文博系统32个单位的专家、学者出席了讨论会.这次讨论会共有27篇论文在会上作了交流,内容涉及热释光(TL)、光释光(OSL)和电子自旋共振测定年代的理论、方法和技术;考古和地质样品年代的测定及其应用;陶瓷器古剂量的测定;释光特性与矿藏成因;热释光、光释光测量仪器研制和改进等.本选编辑录了其中13篇论文予以发表.     

一株耐辐射菌的分离与初步鉴定

对新疆古尔班通古特沙漠土样中分离到的一株耐辐射菌RL2进行了多相分类鉴定.结果发现,此菌为革兰氏阳性,球形,菌落为淡红色;菌株的(G C)mol%含量为71.62%;16S rDNA序列分析表明,菌株RL2的16S rDNA基因序列与D.radiodurans DSM20539T同源性最高(97.2%).通过表型及系统进化树分析,确定RL2菌种分类应归于Deinococcus菌属,并可能是该菌属中的-个新种.     

Activated persulfate by DBD plasma and activated carbon for the degradation of acid orange Ⅱ

In this study, the effect of activated peroxydisulfate(PDS) by dielectric barrier discharge(DBD) plasma and activated carbon(HGAC) on the removal of acid orange Ⅱ(AOⅡ) was investigated. The effects of applied voltage, PDS dosage, HGAC dosage, initial pH value, and inorganic anions on the removal rate of AOⅡ were discussed. The main free radicals degrading azo dyes during the experiment were also studied. Experimental results show that the removal rate of AOⅡ in DBD/HGAC/PDS synergistic system is much higher than that in the single system. With the applied voltage of 16 kV, HGAC dosage of 1 g l-1, PDS and AOⅡ molar ratio of 200:1, initial pH value of 5.4 and concentration of AOⅡ solution of 20 mg l-1, the removal rate of AOⅡ reached 97.6% in DBD/HGAC/PDS process after 28 min of reaction.Acidic and neutral conditions are beneficial for AOⅡ removal. Sulfate and hydroxyl radicals play an important role in the removal of AOⅡ. Inorganic anions are not conducive to the removal of AOⅡ.     

《核科学与工程》征稿简则

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单个浸没孔气泡动力学特性的数值模拟

核电厂发生严重事故时可利用池洗效应去除泄漏的放射性气溶胶。对池洗过程进行两相数值模拟研究是有必要的,在使用两相计算流体力学(CFD)程序计算之前需要确定气泡注入点处的边界条件。基于整合池洗研究(IPRESCA)项目框架和流体体积法(VOF),对单个浸没孔气泡动力学特性进行数值模拟研究,捕捉浸没孔处气泡的大小、形状和脱离频率,并对气泡注入速度对气泡脱离频率的影响进行敏感性分析。利用DBSCAN聚类算法获得了气泡质心高度,并计算得到了不同高度的气泡上升速度。给出了平均空泡份额沿z轴方向的分布,以及平均空泡份额和平均混合速度在不同高度平面沿水平及径向的分布。     

竖直下降两相流相界面结构输运特性

竖直下降两相流具有与竖直上升两相流不同的相界面结构特征及输运特性。本文对竖直下降管内的气水两相流进行了实验研究,运用微型四头电导探针对7.5、31.5及55.5倍管径横截面处的空泡份额、相界面浓度、气泡直径、气泡频率及气泡速度等相界面结构参数的局部分布进行了测量。分析获得了相界面结构参数的沿程变化规律,并研究了气相表观流速对相界面结构发展的影响及一维相界面结构输运特性。发现竖直下降泡状流的升力指向管中心,导致相界面结构参数基本呈中心峰值分布;气相表观流速的增大会提高空泡份额和相界面浓度分布的峰度;竖直下降两相流在距入口31.5倍管径处基本达到充分发展。     

Performance Analysis of Mesh-Packed Cold Traps

SIMMER-IV, a three-dimensional version of SIMMER-III, has been developed at JNC to study the safety of fast reactors mechanistically. SIMMER-IV was applied to the experimental analysis of bubbly flow to verify the models. The results of an experiment performed by Valukina et al. showed that the radial distribution of void fraction changes suddenly as the bubble size changes. In the present work, the analysis focuses on reproducing the change of the radial void distribution. The diffusion term, “lateral lift force,” and “wall force” were introduced in sequence into its momentum conservation equation. Naturally, the diffusion term improved the radial distribution of vertical velocity but did not explain the change of the radial void distribution in the experiment. Subsequent introduction of the lateral lift force increased the void fraction along the wall, but it did not change the radial void distribution as the bubble size changed. Finally, the wall force was introduced and, in accordance with the experimental results, the dependence of radial void distribution on the bubble size was proved. The behavior of a molten pool that is bubbly with steel steam plays an important role in the evaluation of LMFR severe accidents. This study is expected to improve the evaluation.     

Modeling of low-pressure subcooled boiling flow of water via the homogeneous MUSIG approach

Applying a three-dimensional two-fluid model coupled with homogeneous multiple size group (MUSIG) approach, numerical simulations of upward subcooled boiling flow of water at low pressure were performed on the computational fluid dynamics (CFD) code CFX-10 with user defined FORTRAN program. A modified bubble departure diameter correlation based on the Unal's semi-mechanistic model and the empirical correlation of Tolubinski and Kostanchuk was developed. The water boiling flow experiments at low pressure in a vertical concentric annulus from reference were used to validate the models. Moreover, the influences of the non-drag force on the radial void fraction distribution were investigated, including lift force, turbulent dispersion force and wall lubrication force. Good quantitative agreement with the experimental data is obtained, including the local distribution of bubble diameter, void fraction, and axial liquid velocity. The results indicate that the local bubble diameter first increases and then decreases due to the effect of bubble breakup and coalescence, and has the maximum bubble diameter along the radial direction. Especially, the peak void fraction phenomenon in the vicinity of the heated wall is predicted at low pressure, which is developed from the wall repulsive force between vapor bubbles and heated wall. Nevertheless, there is a high discrepancy for the prediction of the local axial vapor velocity.     

Upward air–water bubbly flow characteristics in a vertical square duct

In nuclear engineering fields, gas–liquid bubbly flows exist in channels with various shape and size cross-sections. Although many experiments have been carried out especially in circular pipes, those in a noncircular duct are very limited. To contribute to the development of gas–liquid bubbly flow model for a noncircular duct, detail measurements for the air–water bubbly flow in a square duct (side length: 0.136 m) were carried out by an X-type hot-film anemometry and a multi-sensor optical probe. Local flow parameters of the void fraction, bubble diameter, bubble frequency, axial liquid velocity and turbulent kinetic energy were measured in 11 two-phase flow conditions. These flow conditions covered bubbly flow with the area-averaged void fraction ranging from 0.069 to 0.172. A pronounced corner peak of the void fraction was observed in a quarter square area of a measuring cross-section. Due to a high bubble concentration in the corner, the maximum values of both axial liquid velocity and turbulent kinetic energy intensity were located in the corner region. It was pointed out that an effect of the corner on accumulating bubble in the corner region changed the distributions of axial liquid velocity and turbulent kinetic energy intensity significantly.     

棒束定位格架两相CFD模拟方法研究

考虑气泡合并分裂,采用MUSIG模型,对3×3格架内空气-水两相分布进行计算流体力学(CFD)数值模拟研究发现,计算对入口两相分布预计不敏感,但对气泡直径大小敏感;在定位格架下游不远处,空泡份额分布由较小直径气泡起主导作用,格架下游较远处,空泡份额分布由较大直径气泡起主导作用。考虑空气-水两相流量、几何条件和压力对气泡直径的影响,本文提出针对棒束定位格架的数值模拟气泡最大直径设置关系式,并对模型选取和模拟方法给出建议。计算表明空泡份额分布曲线形状与峰值均和实验符合较好,该模拟方法能合理预测复杂通道两相数值分布。     

Void distribution and bubble motion in bubbly flows in a 4×4 rod bundle. Part II: numerical simulation

Numerical simulations of bubbly flows in a four by four rod bundle are carried out using a multi-fluid model to examine effects of the numerical treatment of phase distribution and drag model. The transport equations of bubble number density and void fraction are used as the continuity equation of the gas phase. Two drag models are tested: one of them accounts for the bubble deformation (aspect ratio), whereas the other does not. The rod diameter, the rod pitch and the hydraulic diameter of the rod bundle are 10, 12.5 and 9.1 mm, respectively. The gas and liquid volume fluxes are J_G = 0.06 m/s and J_L = 0.9 and 1.5 m/s, respectively. The bubble diameter ranges from 1 to 5 mm. Comparisons between the numerical and measured data show that (1) the restriction on bubble lateral motion due to the presence of rods can be taken into account by using the transport equation of bubble number density, whereas that of the void fraction cannot deal with the restriction and causes large errors in the distribution of void fraction and (2) the reduction in the bubble-relative velocity near the wall is predictable by using the drag model accounting for the bubble deformation effect.     

竖直圆管内泡状流界面参数分布特性

采用双头光纤探针对内径为50 mm竖直圆管内空气-水两相泡状流界面参数径向分布特性进行了实验研究。气液两相表观速度变化范围分别为0.004～0.05 m/s和0.071～0.283 m/s。结果表明,竖直管内向上泡状流局部界面面积浓度（IAC）、空泡份额及气泡频率径向分布相类似,即气相流速较低时管道中间很大范围内以上3个局部界面参数几乎恒定,近壁区迅速下降到较低值;随气相流速的增加,局部界面参数在管道中心出现峰值。本实验中气泡聚合与破碎现象较少发生,索特平均直径沿径向近似均匀分布,且随气液两相流速变化很小。通过气泡横向受力解释了局部界面参数分布的影响机理。     

基于竖直圆管空气-水两相流实验的相间曳力模型研究

研究两相流相间阻力特性对系统程序关键本构模型封闭具有重要意义。本文基于竖直圆管开展了空气-水两相流实验,采用四探头电导探针对空泡份额、气泡弦长和界面面积浓度等气泡参数的径向分布进行了测量。结果表明空泡份额和气泡弦长呈现“核峰型”分布,而界面面积浓度并没有表现出随流速的单调关系。进一步开发了泡状流和弹状流的相间曳力模型,考虑了液相表观流速与管径对气泡尺寸分布的影响,建立了临界韦伯数与不同液相流速的关系。计算得到的空泡份额和界面面积浓度与实验数据整体符合较好,验证了模型的可靠性,为两相流相间阻力特性研究提供参考意义。     

Void distribution and bubble motion in bubbly flows in a 4×4 rod bundle. Part I: Experiments

Lack of local void fraction data in a rod bundle makes it difficult to validate a numerical method for predicting gas–liquid two-phase flow in the bundle. Distributions of local void fraction and bubble velocity in each subchannel in a 4×4 rod bundle were, therefore, measured using a double-sensor conductivity probe. Liquid velocity in the subchannel was also measured using laser Doppler velocimetry (LDV) to obtain relative velocity between bubbles and the liquid phase. The size and pitch of rods were 10 and 12.5 mm, respectively. Air and water at atmospheric pressure and room temperature were used for the gas and liquid phases, respectively. The volume fluxes of gas and liquid phases ranged from 0.06 to 0.15 m/s and from 0.9 to 1.5 m/s, respectively. Experimental results showed that the distributions of void fraction in inner and side subchannels depend not only on lift force acting on bubbles but also on geometrical constraints on bubble dynamics, i.e. the effects of rod walls on bubble shape and rise velocity. The relative velocity between bubbles and the liquid phase in the subchannel forms a non-uniform distribution over the cross-section, and the relative velocity becomes smaller as bubbles approach the wall due to the wall effects.