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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A saw-tooth plasma actuator for film cooling efficiency enhancement of a shaped hole

This paper reports the large eddy simulations of the effects of a saw-tooth plasma actuator and the laidback fan-shaped hole on the film cooling flow characteristics,and the numerical results are compared with a corresponding standard configuration (cylindrical hole without the sawtooth plasma actuator).For this numerical research,the saw-tooth plasma actuator is installed just downstream of the cooling hole and a phenomenological plasma model is employed to provide the 3D plasma force vectors.The results show that thanks to the downward force and the momentum injection effect of the saw-tooth plasma actuator,the cold jet comes closer to the wall surface and extends further downstream.The saw-tooth plasma actuator also induces a new pair of vortex which weakens the strength of the counter-rotating vortex pair (CRVP) and entrains the coolant towards the wall,and thus the diffusion of the cold jet in the crossflow is suppressed.Furthermore,the laidback fan-shaped hole reduces the vertical jet velocity causing the disappearance of downstream spiral separation node vortices,this compensates for the deficiency of the saw-tooth plasma actuator.Both effects of the laidback fan-shaped hole and the saw-tooth plasma actuator effectively control the development of the CRVP whose size and strength are smaller than those of the anti-counter rotating vortex pair in the far field,thus the centerline and the spanwise-averaged film cooling efficiency are enhanced.The average film cooling efficiency is the biggest in the Fan-Dc =1 case,which is 80％ bigger than that in the Fan-Dc =0 case and 288％ bigger than that in the Cyl-Dc =0 case.     

Studies on cooling by two-dimensional confined jet flow of high heat heat flux surface in fusion reactor

Divertor surface of a magnetic confinement fusion reactor is exposed to strong radiative heating. According to standard design of the ITER, maximum heat flux on the divertor surface becomes locally near 30 MW m⁻². To cool such high heat flux surface by water flow, it is necessary to establish a cooling method which enhanced the critical heat flux (CHF). We proposed a cooling by a planar impinging jet with free surface in the previous report. In the jet cooling on flat surface, high CHF was obtained in the limited region where the jet flow hits directly. As apart from the region, the CHF decreases abruptly with the distance from the center. To overcome this difficulty, it was proposed that the planar jet is applied to cool concave surface where the centrifugal force is efficiently used to enhance the CHF. In this study, the CHFs were investigated in the confined jet flow which was guarded by a wall on the other side of the heated wall, because the guard wall works to protect splash of water from liquid film by violent boiling and expects further enhancement of the CHF. In this study, the CHFs were investigated in the confined flow of two-dimensional jet on flat and concave surfaces in the various flow conditions and got a correlation for the CHF. Applicability of this cooling for divertor surface was assessed by using the experimental results.     

Liquid film behavior and heat-transfer mechanism near the rewetting front in a single rod air–water system

ABSTRACT

The rewetting front propagation may occur when the fuel rod is cooled by the liquid film flow after it is dried out under accident conditions for boiling water reactor cores. Our previous study has revealed the importance of precursory cooling, defined as a rapid cooling just before the rewetting, which has a significant effect on the propagation velocity. To understand the mechanism of the precursory cooling, we conducted heat-transfer experiments using a single heater rod contained inside the transparent glass pipe to measure heat-transfer behavior with simultaneous observation using a high-speed camera. The results showed characteristic effects of the wall temperature on the liquid film flow and liquid droplets formation at the rewetting front, i.e. sputtering. Even when the liquid film flows in rivulets under adiabatic condition, horizontally uniformed rewetting front was observed with increasing wall temperature due to enhanced flow resistance by sputtering. This sputtering effect was also confirmed from observations of the liquid film thickness, which increased with approaching the rewetting front. Heat-transfer coefficients were predicted roughly well with a single-phase heat-transfer correlation with entrance effects, suggesting that the thinner thermal boundary layer downstream of the rewetting front may be one of the precursory cooling mechanisms.     

Reduction of turbulent boundary layer drag through dielectric-barrier-discharge plasma actuation based on the Spalding formula

Abstract It is a very difficult task to develop a method of reducing turbulent boundary layer drag. However, in recent years, plasma flow control technology has demonstrated huge potential in friction drag reduction. To further investigate this issue, a smooth plate model was designed as a testing object arranged with a bidirectional dielectric-barrier-discharge (DBD) plasma actuator. In addition, measurement of skin friction drag was achieved by applying hot wire anemometry to obtain the velocity distribution of the turbulent boundary layer. A method of quantifying the friction drag effect was adopted based on the Spalding formula fitted with the experiment data. When plasma actuation was conducted, a velocity defect occurred at the two measuring positions, compared with the no plasma control condition; this means that the DBD plasma actuation could reduce the drag successfully in the downstream of the actuator. Moreover, drag reduction caused by backward actuation was slightly more efficient than that caused by forward actuation. With an increasing distance from plasma actuation, the drag-reduction effect could become weaker. Experimental results also show that the improvement of drag-reduction efficiency using a DBD plasma actuator can achieve about 8.78% in the local region of the experimental flat model.     

Influence of a flow obstacle on the occurrence of burnout in boiling two-phase upward flow within a vertical annular channel

When a flow obstruction such as a cylindrical spacer is set in a boiling two-phase flow within an annular channel, the inner tube of which is used as a heater, the temperature on the surface of the heating tube is severely affected by its existence. In some cases, the cylindrical spacer has a cooling effect, and in the other cases it causes the dryout of the cooling water film on the heating surface resulting in the burnout of the heating tube.In the present paper, we have focused our attention on the influence of a flow obstacle on the occurrence of burnout of the heating tube in boiling two-phase flow.The results are summarized as follows:

(1)When the heat flux approaches the burnout condition, the wall temperature on the heating tube fluctuates with a large amplitude. And once the wall temperature exceeds the Leidenfrost temperature, the burnout occurs without exception.

(2)The trigger of dryout of the water film which causes the burnout is not the nucleate boiling but the evaporation of the base film between disturbance waves.

(3)The burnout never occurs at the downstream side of the spacer. This is because the dryout area downstream of the spacer is rewetted easily by the disturbance waves.

     

Investigation of the interaction between NS-DBD plasma-induced vortexes and separated flow over a swept wing

The effect of nanosecond pulsed dielectric barrier discharge(NS-DBD) plasma flow separation control is closely related to the actuation frequency,because it involves the interaction between plasma-induced vortexes and separated flow.In order to study the mechanism of NS-DBD plasma flow separation control over a swept wing,especially the influence of the actuation frequency,at first,experimental studies of the actuation frequencies at 100 Hz are conducted to validate the numerical simulation meth...     

Investigation of the Flow Structure on a Flat Plate Induced by Unsteady Plasma Actuation with DNS Methods

An investigation into the flow characteristic on a flat plate induced by an unsteady plasma was conducted with the methods of direct numerical simulations(DNS).A simplified model of dielectric barrier discharge(DBD) plasma was applied and its parameters were calibrated with the experimental results.In the simulations,effects of the actuation frequency on the flow were examined.The instantaneous flow parameters were also drawn to serve as a detailed study on the behavior when the plasma actuator was applied to the flow.The result shows that induced by the unsteady actuation,a series of vortex pairs which showed dipole formation and periodicity distribution were formed in the boundary layer.The production of these vortex pairs indicated a strong energy exchange between the main flow and the boundary layer.They moved downstream under the action of the free stream and decayed under the influence of the fluid viscosity.The distance of the neighboring vortices was found to be determined by the actuation frequency.Interaction of the neighboring vortices would be ignored when the actuation frequency was too small to make a difference.     

CFD analysis of a turbulent jet behavior induced by a steam jet discharge through a single hole in a subcooled water tank

A computational fluid dynamics (CFD) analysis for a turbulent jet flow induced by a steam jet discharged into a subcooled water pool was performed for 10 s of transients to investigate whether the currently available CFD codes can be suitably used as a tool to investigate the applicability of the existing semi-analytical correlations to a condensing jet-induced turbulent jet and to analyze the thermal-hydraulic behavior, such as global circulation and local hot spot, in a condensation pool for advanced light water reactors. As for the numerical experiment, a series of sensitivity calculations was conducted systematically to elucidate the major factors which can cause different analysis results by varying the mesh distributions, numerical models for a convection term and an eddy viscosity term. The effect of a difference in the velocity and the temperature distribution in a region between the sparger and the pool wall has not been observed in the afore-mentioned sensitivity calculations. The comparison of the CFD results with the test data shows that the CFD analysis does not accurately simulate the local phenomenon of a turbulent jet existing downstream of a steam jet. It was found that the value of the turbulent intensity at the inlet of the turbulent jet region is the most important factor because it can determine the boundary of a turbulent jet through a momentum diffusion process in a radial direction. The comparison of the CFD results with the test data shows that the CFD analysis can accurately simulate the local phenomenon of a turbulent jet existing downstream of a steam jet only when the CFD analysis reflects the physics of a turbulent jet.     

Research on the Peristaltic Flow Acceleration Performance of Asynchronous and Duty Cycle Pulsed DBD Plasma Actuation

Using a plexiglas plate model, the performance of peristaltic flow acceleration in- duced by multiple DBD （dielectric barrier discharge） plasma actuators was studied based on PIV （particle image velocimetry）. The asynchronous and the duty cycle pulsed actuation modes were proposed and tested. The velocity fields induced by multiple DBD plasma actuators with different phase angles and duty cycle ratios were acquired and the momentum transfer characteristics of the flow field were discussed. Consequently, the mechanism of the peristalsis-acceleration multi- ple DBD plasma actuation was analyzed. The results show that the peristaltic flow acceleration effect of multiple plasma actuators occurs mainly in paraelectric direction, and the mechanism of peristaltic flow acceleration is ejection pushing effect rather than injection pumping effect. The asynchronous and the duty cycle pulsed actuation modes can, with energy consumption increase of merely 10%, achieve 65% and 42% increase of downstream velocity, and thus are promising in velocity improvement and energy saving.     

Effect of insulating oil covering electrodes on the characteristics of a dielectric barrier discharge

In this study, the effects of the fluid cooling and electric field line deformation were investigated in a dielectric barrier discharge (DBD) plasma source. The DBD plasma jet is improved by covering the ground electrode and a power electrode with insulating oil. We obtained positive results as insulating oil prevents arc formation, while it improved the supplied power and plasma jet length, and increased radical production. Radical production of this nonthermal plasma jet is studied with polyvinyl alcohol–potassium iodide liquid.