ITER水平诊断窗口冷却回路结构设计与流体分析

水平诊断窗口位于ITER装置主机水平窗口,用于容纳各项等离子体诊断设备,需要满足水冷、电磁和射线屏蔽等功能的技术要求。基于结构可靠性与加工可行性设计了水平诊断窗口冷却回路,并采用FLUENT软件进行传热和流体动力学理论计算,得到了流体流速、压力和温度分布等数值模拟结果。并通过比较和分析,优化了结构设计。保证其冷却回路能够平衡窗口框体在受等离子体辐射热时产生的34 kW热负荷,阻挡等离子体辐射热对内部诊断设备的影响,同时降低了加工难度,为ITER水平诊断窗口插件的最终设计提供依据。     

重视非IE用户:用NPAPI开发跨浏览器的插件

<正>相信大家在使用浏览器的时候都安装过插件(Plug-ins),比如在使用QQ邮箱,看Flash、用网银付款等等。然而,很多人也会发现,有时候我们在Firefox或者Chrome下,有些插件是无法安装的。其原因是这里安装的插件是按照微软自己的ActiveX标准开发的,而不适用于     

Flash病毒疫情泛滥 黑客再次掀起木马狂潮

<正>近期,微点主动防御软件自动捕获木马数量异常增高,微点反病毒专家分析与近期IE浏览器falsh播放插件漏洞有较大关系。因IE等浏览器falsh播放器插件安装率极高,可以说全球计算机用户都受到了严重威胁。且由于该插件缺乏自动更新机制等原因     

DSA体模研究及遥控装置的应用

为解决医用诊断数字减影血管造影(DSA)系统性能检测及检测人员操作时不受X射线的辐照,研制一套改进的DSA计量性能体模装置。体模的设计采用有机玻璃材料进行加工;模块的移动采用无线电信号遥控的方法;体模的性能试验在正常状态的DSA系统上进行。研究设计有机玻璃动脉模拟模块插件、骨骼模块插件、对比度线性模块插件和低对比度分辨力模块插件;模块的移动利用遥控驱动装置。试验得到:在不加载骨骼模块时,能看到直径为1mm的动脉模拟血管,同时能分辨直径2mm的模拟血管上1/2血管大小的血管瘤或栓塞;加载骨骼体模块后,可以分辨碘浓度为150mg/cm3、直径2mm的模拟动脉;遥控装置遥控距离50m,移动速度28mm/s。结果表明:体模装置完全符合国家规程JJG 1067——2011《医用诊断数字减影血管造影(DSA)系统X射线辐射源》要求;应用无线电遥控移动模块插件,避免操作时受到X射线的照射。     

微晶硅同质结薄膜太阳电池的数值模拟分析

采用太阳电池电容模拟软件(简称SCAPS)对p-i-n结构的微晶硅同质结薄膜太阳电池进行了数值模拟。研究了本征层的厚度和缺陷态浓度及窗口层的厚度等参数对电池性能的影响。得到的主要结论如下:(1)随着本征层缺陷态浓度Nt的增加,电池的各性能参数均单调下降。(2)随着本征层厚度的增加,长波段的光谱响应逐渐改善,但该层过厚则导致中波段的光谱响应急剧下降,在Nt=1.0×1016/cm3的条件下,本征层厚度在1.5～2.0μm范围内电池效率均可达到7.0%以上。(3)p型窗口层的厚度对短波段的光谱响应及短路电流密度JSC有较大影响。     

新型超支化聚合物电解质的合成及电化学性能研究

以双三氟甲基磺酸亚胺锂(LiTFSI)为溶质、三乙二醇双甲醚(TGE)为溶剂制备的电解液为介质,将超支化聚醚(PHEMO)与六次甲基二异氰酸酯(HDI)缩合生成了一种新型的超支化聚合物电解质(超支化聚氨酯,简称PHEU).利用交流阻抗技术对聚合物电解质的离子导电性能进行了研究,结果表明:温度、电解液添加量、锂盐浓度的变化均对离子电导率有较大的影响;该聚合物电解质室温离子电导率可达0.612×10-3S/cm.采用循环伏安法测得聚合物电解质的电化学稳定窗口为2～5V,可以满足锂离子电池的要求.     

测长机(仪)测头错位所造成的误差浅析

在测长机(仪)的检定和使用中,对测钩的安装无明确规定,安装时可能产生较大的错位量(如将测头反向安装,轻微转拨测钩,可见到0.5mm～1mm的明显测头错位),在测量孔径时将产生极大的误差,在此对其进行分析。     

用SiCl4/H2沉积纳米晶硅薄膜过程中氢稀释量对SiCln(n=0～2)密度的影响

用质谱、朗缪尔探针诊断技术研究了氢稀释的SiCl4作为源气体,用等离子体增强化学气相方法进行纳米晶硅薄膜的生长.进一步研究了氢稀释比率对SiCl4等离子体中SiCln(n=0～2)基团浓度的影响.等离子体中,平均电子能量和电子密度分别随着氢稀释比率的增加而达到9.25eV和3.7×109cm-3.结果发现,在0.4～0.67范围的氢稀释比率对于形成SiCln(n=0～2)基团很有利.在这个范围,平均电子能量和电子密度都有较大的值.生成较多的SiCln(n=0～2)基团将有利于提高薄膜沉积速率和薄膜质量.     

重视非IE用户：用NDApI开发跨济览器的插件

相信大家在使用浏览器的时候都安装过插件（Plug-ins），比如在使用QQ邮箱看Flash、用网银付款等等。然而，很多人也会发现，有时候我们在Firefox或者ChromeT，有些插件是无法安装的。其原因是这里安装的插件是按照微软自己的Activex标准开发的，而不适用于其他浏览器。由于IE6在国内长期占据统治地位，因此有很多网站和网络应用都采用了ActiveX标准进行开发。导致用户使用其他非IE浏览器时无法运行这部分程序。目前这个问题最广泛的例子就是广大银行的网银，相信大家也都知道大部分网银只能在IE和     

利用离子交换改性法提高分子筛在低压下的吸附量和吸附速率

自从沸石分子筛问世以来,由于其独特的结构,在气体和液体的分离、净化、干燥、环保等方面取得了广泛的应用。特别是由于分子筛的微孔中存在着强大的吸附力场,使其在真空情况下,对气体仍具有较大的吸附量,已在低温吸附泵中得到广泛的应用。近年来在各种电真空器件的应用中,亦取得明显的效果,日益受到重视。六十年代中期,已有学者对分子筛在低压下对空气及其主要成份如N_2,O_2、Ar等非极性分子的吸附性能进行了研究。首先测定了在1×10~(-2)～5000帕压强下,在液氮温度时,A、X型分子筛对N_2、Ar等的吸附等温线。结果表明5A、13X分子筛有明显的吸附能力,并且对N_2的吸附能力显著大于Ar。等测定了在1×10~(-3)～10帕的压强下,液氮温度时,A、X型分子筛对空气的吸附等温线也有类似的结果。本文提供了能在1.0×10(-2)～1.0×10~(-5)帕高真空范围内测量分子筛的吸附量和吸附速率的实验方法。这就是真空定容法和高真空定压法,分别测定吸附量和吸附速率。这两个方法比较合理地解决了国产分子筛的吸气速率的测试。本文比较了5A,13X,M型和ZSM—5型四种分子筛在不同平衡压强下对氮气的吸附量,发现5A,13X在1.33×10~(-3)～1.33×10~(-2)帕范围内吸附量较大,但在1.33×10~(-4)～1.33×10~(-3)帕范围内不理想,不能将它用在真空器件中。而把这几种分子筛用离子交换法进行改性后,M型分子筛交换Ca~( )离子后,在1.33×10~(-4)～1.33×10~(-2)帕范围内吸附量明显上升,在1.33×10~(-3)～1.33×10~(-2)帕范围内吸附量也和13X差不多。而且测量出交换了Ca~( )离子的M型分子筛在较高真空度时对空气吸附速率大于13X。离子交换法是分子筛改性的好方法,它能提高分子筛的吸附量和吸附速率。M型分子筛是一种较新型的分子筛,进行改性后在高真空状况下吸附量和吸速率又较大,因此它是一种理想的吸气剂。我们将这种M型分子筛加入适当的粘结剂在国内红外探测器的真空元件中得到了应用,使该器件真空度提高2—3个数量级,寿命也明显增加。本文也比较了加入适量的粘结剂分子筛的吸附量和吸附速率的影响,与其他吸气剂一样,吸气量和吸气速率略有降低。     

Real gas choked flow conditions at low reduced-temperatures

Real gas choked mass flux is calculated for a frictionless stream expanding isentropically until it reaches the speed of sound and without phase changes. The other parameters associated with the choked state are the pressure, density, temperature ratios, and the speed of sound. Departure of the choked mass flux from the ideal gas model is discussed first in absolute terms and then in relative terms, using the Principle of Corresponding States, for gases with boiling points in the low temperature range. Reduced-stagnation pressures are examined up to values of 30 for hydrogen, neon, nitrogen, argon, methane, krypton, xenon, and R-14 and up to 100 for ⁴He. The corresponding reduced-stagnation temperatures go down to 1.4 and in some cases down to 1.2 for nitrogen and argon. Also discussed are the limiting values of stagnation parameters for which no phase change occurs in the choked state. Compared to the ideal gas, the mass flux may almost double and the critical pressure ratio may decrease by an order of magnitude. The relevance of results is discussed qualitatively and quantitatively for Joule-Thomson cryocooling.     

As-cast microstructures and behavior at high temperature of chromium-rich cobalt-based alloys containing hafnium carbides

Hafnium is often used to improve the high temperature oxidation resistance of superalloys but not to form carbides for strengthen them against creep. In this work hafnium was added in cobalt-based alloys for verifying that HfC can be obtained in cobalt-based alloys and for characterizing their behavior at a very temperature. Three Co–25Cr–0.25 and 0.50C alloys containing 3.7 and 7.4 Hf to promote HfC carbides, and four Co–25Cr– 0 to 1C alloys for comparison (all contents in wt.%), were cast and exposed at 1200 °C for 50 h in synthetic air. The HfC carbides formed instead chromium carbides during solidification, in eutectic with matrix and as dispersed compact particles. During the stage at 1200 °C the HfC carbides did not significantly evolve, even near the oxidation front despite oxidation early become very fast and generalized. At the same time the chromium carbides present in the Co–Cr–C alloys totally disappeared in the same conditions. Such HfC-alloys potentially bring efficient and sustainable mechanical strengthening at high temperature, but their hot oxidation resistance must be significantly improved.     

Capacitance based mass metering for cryogenic fluids

This paper describes a method for measuring the mass of cryogenic fluids in on-board rocket propellant tanks or ground storage tanks. Linear approximations to the Clausius-Mossotti relationship serve as the foundation for a capacitance based mass sensor, regardless of fluid density stratification or tank shape. Sensor design considerations are presented along with the experimental results for a capacitance based mass gage tested in liquid nitrogen. This test data is shown to be consistent with theory resulting in a demonstrated mass measurement accuracy of ±0.75% and a deviation from linearity of less than ±0.30% of full scale mass. Theoretical accuracies are also shown to be ±0.73% for hydrogen and ±1.39% for oxygen for a select range of pressures and temperatures.     

Equipment using a “static-analytic” method for solubility measurements in potentially hazardous binary mixtures under cryogenic temperatures

A new apparatus designed to study, at cryogenic temperatures, thermodynamic equilibria of potentially explosive binary systems such as hydrocarbon-oxygen mixtures is described herein. This equipment has an equilibrium cell which was especially designed to minimize hazards while allowing accurate phase equilibrium measurements. Reliability of results, obtained with this equipment has been verified by working on the nitrogen-propane system, for which data are already available in literature, over a large range of compositions and at various temperatures. Four isothermal curves describing liquid phase compositions at 109.98, 113.77, 119.75 and 125.63 K have been determined. Our experimental data are represented within 2% in compositions and in pressures through the Peng-Robinson equation of state implying Mathias-Copeman alpha function and Huron-Vidal mixing rule. Comparisons to literature allow pointing out: good agreement is observed with Kremer and Knapp data (1983) while the three sets of Poon and Lu data (1974) presenting systematic positive deviation are consequently judged as suspicious.     

Gas gap thermal switches using neon or hydrogen and sorption pump

The very low pressure obtained thanks to adsorption phenomenon at low temperature can be used to build cryogenic heat switches, which offer the possibility to make or break thermal contact between two parts of a cryogenic system. The ON (conducting) and OFF (insulating) states of the switch are obtained by varying the gas pressure between two copper blocks separated by a gap of 100 μm. This pressure is controlled by acting upon the temperature of a small sorption pump (activated charcoal) connected to the gap space. For a “high” sorption pump temperature, the gas previously adsorbed in the sorption pump is released to the gap between the two blocks, allowing a good thermal conduction through the gas (ON state). On the opposite, cooling the sorption pump allows a very good vacuum between the copper blocks, which efficiently break the thermal contact (OFF state). Experimental thermal characteristics (Conductance in the ON and OFF state, ON-OFF switching temperature) of such a “Gas Gap Heat Switch” are described using hydrogen or neon as exchange gas and are compared with theoretical calculations.     

Development of No-Vent™ liquid hydrogen storage system for space applications

A number of technological advances required to store and maintain normal-boiling-point and densified cryogenic liquids, including liquid hydrogen, under zero boil-off conditions in-space, for long periods of time, have been developed. These technologies include (1) thermally optimized compact cryogen storage systems that reduce environmental heat leak to the lowest-temperature cryogen, which minimizes cryocooler size and input power, and (2) actively-cooled shields that surround the storage systems and intercept heat leak. The processes and tools used to develop these technologies are discussed. A zero boil-off liquid hydrogen storage system technology demonstrator for validating the actively-cooled shield technology is presented.     

Integrated Resonant Self-Pumped Loop and pulse tube cryocooler for cryogenic cooling distribution

Cooling distribution is a vital technology concerning cryogenic thermal management systems for many future space applications, such as in-space, zero boil-off, long-term propellant storage, cooling infrared sensors at multiple locations or at a distance from the cryocooler, and focal-plane arrays in telescopes. These applications require a cooling distribution technology that is able to efficiently and reliably deliver cooling power (generated by a cryocooler) to remote locations and uniformly distribute it over a large-surface area. On-going efforts by others under this technology development area have not shown any promising results.This paper introduces the concept of using a Resonant Self-Pumped Loop (RSPL) integrated with the proven, highly efficient pulse tube cryocooler. The RSPL and pulse tube cryocooler combination generates cooling power and provides a distributive cooling loop that can be extended long distances, has no moving parts, and is driven by a single linear compressor. The RSPL is fully coupled with the oscillating flow of the pulse tube working fluid and utilizes gas diodes to convert the oscillating flow to one-directional (DC) steady flow that circulates through the cooling loop. The proposed RSPL is extremely simple, lightweight, reliable, and flexible for packaging. There are several requirements for the RSPL to operate efficiently. These requirements will be presented in this paper. Compared to other distributive cooling technologies currently under development, the RSPL technology is unique.     

Development of a miniature cryogenic fluid circuit and a cryogenic micropump

This article presents the development of a miniaturized cryogenic fluid circuit for distributed cooling of low-temperature tracking detectors in high-energy physics (HEP). The heart of the circuit is a prototype cryogenic micropump. This volumetric pump is compatible with cooling powers of about 10-100 W, and capable of producing pressure heads of up to around 0.3 MPa. Besides detector and electronics cooling in HEP, potential applications are found in the field of superconductor technology.     

Helium liquefaction with a commercial 4 K Gifford-McMahon cryocooler

This paper describes helium liquefaction using a commercial cryocooler with 1.5 W cooling power at 4.2 K (Sumitomo model RDK415D with compressor CSW-71D, consuming 6.5 kW electrical power), equipped with heat exchangers for precooling the incoming gas. No additional cooling power of cryoliquids or additional Joule-Thomson stages were utilized. Measurements of the pressure dependence of the liquefaction rate were performed. A maximum value of 83.9 g/h was obtained for 2.25 bar stabilized input pressure. Including the time needed to cool the liquefied helium to 4.2 K at 1 bar after filling the bottle connected to the cold head, and correcting for heat screen influences, this results in a net liquefaction rate of 67.7 g/h. Maintaining a pressure close to 1 bar above the bath during liquefaction, a rate of 55.7 g/h was obtained. The simple design enables many applications of the apparatus.     

Cryogenic propellant liquefaction and storage for a precursor to a human Mars mission

An analysis of cryogenic liquefaction and storage methods for in-situ produced propellants (oxygen and methane) on Mars is presented. The application is to a subscale precursor sample return mission, intended to demonstrate critical cryogenic technologies prior to a human mission. A heat transfer analysis is included, resulting in predicted cryogenic tank surface temperatures and heat leak values for different conditions. Insulation thickness is traded off against cryocooler capacity to find optimum combinations for various insulation configurations, including multilayer insulation and microspheres. Microsphere insulation is shown to have promise, and further development is recommended.