钯膜分离氢氦过程中浓差极化现象

根据设计,未来聚变堆等离子体排灰气中除了氘氚还含有以惰性气体为主的杂质气体,会在钯膜纯化氢同位素的过程中产生不容忽视的浓差极化现象,降低排灰气的处理效率。针对这一现象,以氢氦混合气为源项,研究了钯膜在分离氢氦过程中浓差极化对渗氢性能的影响,利用极化系数对浓差极化的程度进行评估,并考察了渗氢驱动力、氦气浓度以及原料气流量对极化系数的影响。结果表明：在150,300,450 kPa时的H2/He选择性分别为37 460,18 347和7935,可以看出钯膜致密性良好;浓差极化系数随着渗氢驱动力和氦气浓度的升高而增大,对于原料气流量的变化则呈现相反趋势。     

氦氢混合气体中受激拉曼散射的脉宽特性

308nm准分子激光泵浦的氢拉曼散射介质中渗入一定比分的氦气,其输出的一阶斯托克斯光S1的脉宽将发生变化。实验获得不同氦比分的S1脉宽在20-45ns之间,与渗入氦的浓度有关。从氦对氢拉曼增益系数的影响,对实验结果进行了理论分析。     

氦氢混合气体中受激拉曼散射的脉宽特性

 308nm准分子激光泵浦的氢拉曼散射介质中渗入一定比分的氦气，其输出的一阶斯托克斯光S1的脉宽将发生变化。实验获得不同氦比分的S1脉宽在20-45ns之间，与渗入氦的浓度有关。从氦对氢拉曼增益系数的影响，对实验结果进行了理论分析。     

氦氮氧混合气湿度计算及实验研究

在海洋科学考察与海洋资源开发的潜水作业中,通常都采用以氦气为主要成分的氦氮氧混合气(以下简称氦混合气)做深潜的呼吸气。氦的热力学性质与空气的有很大差别。氦气的导热系数为空气的五倍多,因此潜水员对氦混合气环境的温度和湿度都极为敏感;氦气的质量比热约为空气的六倍,适用于空气的湿度计算式及干湿球温度与相对湿度的对照表不能用于氦混合气。显然,精确测定并计算氦混合气的湿度,对推动潜水科学     

纳米晶LaNiAl薄膜充氦技术研究

采用离子束辅助磁控溅射方法沉积出了纳米晶LaNiAl膜和纳米晶渗氦LaNiAl膜（膜厚约10 m）,通过调节Ar-He气氛的比例可控制纳米晶膜中的含氦量（He/LaNiAl的原子分数5.7%~13.8%）,通过该方法引入到LaNiAl金属薄膜中的氦量远高于采用球磨法制备的纳米LaNiAl粉中的含氦量。研究结果表明：渗氦LaNiAl膜中的氦含量（原子分数）可达13.9%,氦在膜的深度方向分布均匀;热解析分析恒温条件下沉积的渗氦膜的起始释放温度为848 K,最高释放温度为1407 K,主释放峰为1080 K,初步确定了氦主要是以团簇的形式存在于在纳米晶膜中。     

纳米晶LaNiAl薄膜充氦技术研究

采用离子束辅助磁控溅射方法沉积出了纳米晶LaNiAl膜和纳米晶渗氦LaNiAl膜（膜厚约10 m）,通过调节Ar-He气氛的比例可控制纳米晶膜中的含氦量（He/LaNiAl的原子分数5.7%~13.8%）,通过该方法引入到LaNiAl金属薄膜中的氦量远高于采用球磨法制备的纳米LaNiAl粉中的含氦量。研究结果表明:渗氦LaNiAl膜中的氦含量（原子分数）可达13.9%,氦在膜的深度方向分布均匀;热解析分析恒温条件下沉积的渗氦膜的起始释放温度为848 K,最高释放温度为1407 K,主释放峰为1080 K,初步确定了氦主要是以团簇的形式存在于在纳米晶膜中。     

纳米晶LaNiAl薄膜充氦技术研究（英文）

采用离子束辅助磁控溅射方法沉积出了纳米晶LaNiAl膜和纳米晶渗氦LaNiAl膜(膜厚约10μm),通过调节ArHe气氛的比例可控制纳米晶膜中的含氦量(He/LaNiAl的原子分数5.7%~13.8%),通过该方法引入到LaNiAl金属薄膜中的氦量远高于采用球磨法制备的纳米LaNiAl粉中的含氦量。研究结果表明:渗氦LaNiAl膜中的氦含量(原子分数)可达13.9%,氦在膜的深度方向分布均匀;热解析分析恒温条件下沉积的渗氦膜的起始释放温度为848K,最高释放温度为1407K,主释放峰为1080K,初步确定了氦主要是以团簇的形式存在于在纳米晶膜中。     

自旋极化氢(H↓)超流气体吸附膜中声模式

本文讨论了氦膜上自旋极化氢(H↓)气体超流吸附膜中声模式,与由于膜厚变化引起的氦膜第三声不同,它主要是气膜可压缩性引起的二维第四声。 关键词：     

等离子体排灰气处理技术研究进展

等离子体排灰气处理系统是聚变反应装置氘氚燃料循环系统中极为重要的环节。该系统的主要功能是从反应后的排灰气中回收剩余的氘氚燃料,并处理壁材料净化、系统维护等非正常运行模式以及分析与辅助系统中产生的含氚杂质气体。介绍了国际上聚变堆等离子体排灰气的组成和主要处理工艺,简述了钯膜分离、膜反应及催化反应-膜分离、电解反应、分解反应及氧化-分解等各关键单元技术的基本原理和研究进展,并进行了分析和评价,提出了目前国内在该领域需要开展的研究工作。     

等离子体排灰气处理技术研究进展

等离子体排灰气处理系统是聚变反应装置氘氚燃料循环系统中极为重要的环节。该系统的主要功能是从反应后的排灰气中回收剩余的氘氚燃料,并处理壁材料净化、系统维护等非正常运行模式以及分析与辅助系统中产生的含氚杂质气体。介绍了国际上聚变堆等离子体排灰气的组成和主要处理工艺,简述了钯膜分离、膜反应及催化反应-膜分离、电解反应、分解反应及氧化-分解等各关键单元技术的基本原理和研究进展,并进行了分析和评价,提出了目前国内在该领域需要开展的研究工作。     

Numerical simulation of tissue freezing by liquid nitrogen based cryoprobe

A model is presented to simulate the cooling processes during tumor cryosurgery with different kinds of flows through the cryoprobe. The heat flux between the cryoprobe wall and the tumor, the heat transfer coefficient under different inflow conditions are obtained numerically. The impact of the inlet mass flow rate, gas volume fraction on these parameters is investigated. It is found that the heat transfer coefficient decreased significantly when inflow changed from two-phase annular flow to droplet flow, and to gas flow. The inlet gas volume fraction and flow velocity only significantly affect the freezing ability of the probe when the inflow is gas or in droplet phase. Simulation of the tumor temperature profiles under different flow conditions show that the heat transfer coefficient is a crucial parameter in temperature prediction during cryosurgery. Results indicate that when the cryoprobe wall is assumed at a constant temperature conventionally, the cooling effect could be overestimated. It would be more reasonable to use the constant wall heat transfer coefficient to simulate the cooling progress under a specific flow.     

Influence of carrier gas pressure and flow rate on atomic layer deposition of HfO2 and ZrO2 thin films

Influence of the carrier gas on HfCl₄-H₂O and ZrCl₄-H₂O atomic layer processes was investigated. The growth rates of HfO₂ and ZrO₂ decreased with increasing flow rate and pressure of the N₂ carrier gas. Data of real-time quartz crystal microbalance measurements demonstrated that the effect observed was mainly due to influence of carrier gas on surface reactions and the role of overlapping the precursor pulses was negligible. At the same increase of the carrier gas mass flow, the increase of the linear flow rate led to more significant changes of thin-film properties than the increase of the carrier gas pressure did. Thin films with higher density, higher refractive index and, particularly, lower concentration of residual chlorine were obtained at higher carrier gas flow rates. Increase of the carrier gas flow rate also resulted in a higher concentration of a metastable phase in HfO₂ thin films deposited at 300 °C.     

Optical pumping system design for large production of hyperpolarized

We present a design for a spin-exchange optical pumping system to produce large quantities of highly polarized 129Xe. Low xenon concentrations in the flowing gas mixture allow the laser to maintain high Rb polarization. The large spin-exchange rate between Rb and 129Xe through the long-lived van der Waals molecules at low pressure, combined with a high flow rate, results in large production rates of hyperpolarized xenon. We report a maximum polarization of 64% achieved for a 0.3 l/h Xe flow rate, and maximum magnetization output of 6 l/h at 22% polarization. Our findings regarding the polarization dependence on temperature, nitrogen partial pressure, and gas mixture flow velocity are also reported.     

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对感应耦合氩气热等离子体的速度分布特性以及各操作参数对等离子体速度分布的影响进行了细致的研究。研究结果表明,与直流电弧热等离子体相比,感应耦合热等离子体速度小,弧流集中,速度峰值出现在等离子体炬下游,在线圈段上游出现明显的回流现象。此外,送气流量、感应电流等操作参数对等离子体速度分布有明显影响。研究结果可为等离子体球化粉末颗粒及其他应用提供理论指导。     

Dependence of properties of hydrogenated microcrystalline and amorphous silicon films prepared by planar magnetron sputtering in inert gas

Microcrystalline and amorphous hydrogenated silicon films were preparaed by rf planar magnetron sputtering in the four kinds of inert gas, i.e., He, Ne, Ar, and Kr. The dependence of such properties as x-ray diffraction, ir spectra, absorption coefficient, hydrogen content, dark conductivity and photoconductivity on the kind of inert gas was investigated. Such deposition conditions as hydrogen partial pressure, sputtering pressure and rf power were also studied mainly in relation to the microcrystallization of the films. Microcrystalline films with noticeably high deposition rate could be obtained in the case of Kr and Ar, compared to the case of He and Ne. Hydrogen concentration was found to correlate to the photoconductivity and activation energy of dark conductivity except for the case of He. Photosensitivity was appreciably larger for amorphous film than for microcrystalline one. Especially in the case of Kr, it was considerably larger than in other cases.     

射频感应等离子体制备球形钛粉的工艺研究

采用单因素法对制备球形钛粉的工艺进行研究,通过控制和调节射频等离子体工作的阳极电流与电压、中气流量、边气流量、粉体携带气流量、抽风负压和钛粉送粉速率等参数,以获得制备球形度较佳的钛粉工艺参数。通过射频感应等离子体对粒度为(17.02.0) m的钛粉球化处理研究,制备出球形度好、球化率高、表面粗糙度低的钛粉,钛粉球化率随着抽风负压增加而增加,当抽风负压大于1 800 Pa时,钛粉的球化率随着抽风负压的增大迅速降低;同样钛粉球化率也随着钛粉送粉速率增加而增加,当钛粉送粉速率大于90.0 g/min时,钛粉的球化率随着钛粉送粉速率的增大而迅速降低。     

Spectroscopic issues in optical polarization of 3He gas for Magnetic Resonance Imaging of human lungs

The Magnetic Resonance Imaging (MRI) of human lungs for diagnostic purposes became possible by using nuclear spin hyperpolarized noble gases, such as ³He. One of the methods to polarize ³He is the Metastability Exchange Optical Pumping (MEOP), which up to now has been performed at low pressure of about 1 mbar and in low magnetic field below 0.1 T (standard conditions). The equilibrium nuclear polarization can reach up to 80%, but it is dramatically reduced during the subsequent gas compression to the atmospheric pressure that is necessary for the lungs examination. Further polarization losses occur during the transportation of the gas to the hospital scanner. It was shown recently that up to 50% polarization can be obtained at elevated pressure exceeding 20 mbar, by using magnetic field higher than 0.1 T (nonstandard conditions). Therefore, following the construction of the low-field MEOP polarizer located in the lab, a dedicated portable unit was developed, which uses the magnetic field of the 1.5 T MR medical scanner and works in the continuous-flow regime. The first in Poland MRI images of human lungs in vivo were obtained on the upgraded to ³He resonance frequency Siemens Sonata medical scanner. An evident improvement in the image quality was achieved when using the new technique. The paper shows how spectroscopic measurements of ³He carried out in various experimental conditions led both to useful practical results and to significant progress in understanding fundamental processes taking place during MEOP.     

惰性气体对HFCVD沉积金刚石气相基团的影响

发射光谱法是对等离子进行在线诊断的常用方法。在丙酮/H2、丙酮/H2/He和丙酮/H2/Ar三种体系中,对热丝化学气相沉积金刚石薄膜过程中的等离子体进行了在线测量。研究了不同体积分数的惰性气体对等离子体中各活性基团强度的影响,以及CH,H与C2的相对强度的比值、电子温度的大小随惰性气体体积分数的变化关系。结果表明,各基团的强度随着惰性气体体积分数的增加呈现上升趋势,且加入同体积分数的氩气比加入氦气的影响更大;CH,H与C2的相对强度比值、电子温度随着惰性气体体积分数的增加而呈现下降趋势,且在丙酮/H2/Ar体系中要比丙酮/H2/He体系中小。     

The use of ultrasound to reduce internal concentration polarization in forward osmosis

Unlike reverse osmosis (RO) that is dominated by the hydraulic pressure differential, forward osmosis (FO) uses the osmotic pressure gradient as the driving force between a dilute feed solution and a concentrated draw solution across a membrane. High pressure is not required in FO, which means that FO can be used as an alternative to RO as an energy-saving separation process in desalination technology. However, a major limiting factor of the FO process is the internal concentration polarization (ICP). Because of the stagnant environment inside the porous supporting layer of a FO membrane, it is difficult to mitigate the ICP by simply increasing the shear stress or promoting turbulence. In this study, the ICP is reduced by ultrasound. The effect of the ultrasound frequency and output power on the ICP coefficient is investigated in a flat-sheet FO membrane module with counter-current flow. The ultrasound frequency and output power are varied between 25, 45, and 72 kHz and over the range of 10–70 W, respectively. NaCl solution is used as both the feed and draw solution. The results illustrate that moderate ultrasonic irradiation is effective for reducing the ICP in a FO process. A modified solution–diffusion model based on film theory is used to assess the effect of ultrasound on the ICP in a FO process. The ICP coefficient is estimated using this model.