10-10 Pa溅射离子泵和非蒸散型吸气剂的复合泵

不改变商用SIP的基本结构,把NEG组件WP1250装入SIP,构成(SIP NEG)的XHV复合泵.它使SIP和NEG的特点互补,综合性能优越.NEG激活前,SIP单独抽气,极限压强1.1×10-8Pa.NEG激活后,SIP和NEG联合抽气,复合泵的极限压强降到7×10-10Pa,抽速稳定的范围更广,标称抽速约是SIP抽速的2.5倍.     

NEG泵抽气性能仿真模拟与测试系统设计

烧结型非蒸散吸气剂(NEG)泵HV400具有对氢及氢同位素有很高的亲和力,即使室温状态下也能发生吸附效应。为了适用于EAST托卡马克中性束注入器工作条件下稳定抽气,针对HV400的抽气性能开展了模拟仿真和实验研究。采用Molflow软件仿真分析了工作状态下不同进气量的压力分布规律与抽气性能,得到了系统平衡压力与进气量以及抽速随着平衡压力而变化的特性曲线,发现三种气体在10^-3～10^-2 Pa时抽速有微小起伏,表明HV400对H₂、CO₂和N₂抽气性能稳定,评估结果与实际抽速相比误差分别为1.95%、3.13%和2.09%,均在合理误差范围内。基于标准化流量计法完成了NEG泵抽速测试系统设计与平台搭建,并进行了抽速性能测试实验,实验结果与仿真模拟都验证了系统设计的可行性,且在10^-3 Pa量级下抽氢效果最好,为NEG泵在中性束注入器的真空系统设计提供了理论依据和技术支持。     

非蒸散型吸气剂泵(NEG)对N_(2)气的抽气特性研究北大核心CSCD

非蒸散型吸气剂泵(NEG)是采用过渡族金属材料的吸气特性制作成的真空泵,用于超高/极高真空环境的获得及气体的纯化等方面。本文研制出吸气剂泵性能测试系统,研究了非蒸散型吸气剂泵对N_(2)气的抽气特性,分析了影响抽气性能的因素。研制的系统采用标准流量抽速测试方法,采用固定流导法流量计提供(10^(-5)~10^(-8))Pam^(3)/s的标准气体流量,可在测试罩内获得(10^(-2)~10^(-5))Pa的气体压力下实现抽速测试。实验结果表明,NEG泵激活后处于最佳抽气状态,当抽速下降之后可在超高真空条件下放置一段时间将抽速恢复至初始状态,但泵的整体抽气性能发生一定变化;当泵连续抽气时,抽速随着吸气量的增大而逐渐减小,随着泵抽气压力的增大而减小。     

复合泵在医用重离子加速器上的应用研究

同步加速器是医用重离子加速器的主加速部件。考虑到其设计空间紧凑的特点及其真空系统的设计要求,采用将非蒸散型吸气剂泵(NEG)组件嵌入国产溅射离子泵(SIP)空腔内组成的复合泵作为真空系统的主泵。本文测试了复合泵的抽气性能,测试并估算了复合泵的H2饱和容量和再生周期,计算了同步加速器真空系统的压力分布。测试及计算结果表明:相比于SIP,复合泵对N2的抽速提高了20%,对H2的抽速提高了70%～100%,且具有更高的极限真空度,其再生周期为2年,压力分布能够满足同步加速器真空系统的设计要求。     

极高真空校准室内残余气体的成分分析

用四极质谱计对316L不锈钢制作的极高真空(XHV)校准室在烘烤前、后的残余气体成分进行了分析。一个热阴极电离规(IE514)和一个四极质谱计(QMS200)连接在XHV校准室上。烘烤前,开、关热阴极电离规以及对其进行除气,放出的气体主要有H2O、CO、H2、CH4和CO2。烘烤后,开、关热阴极电离规以及对其进行除气,放出的气体主要有CO、H2、CO2和CH4。整个烘烤过程完成后2h,XHV校准室内的压力在室温下通过分子泵串联抽气机组抽至8.97×10-9Pa,用四极质谱计分析到的残余气体成分主要为H2和CO。整个烘烤过程完成后4h,打开非蒸散型吸气剂泵(NEGP)对XHV校准室抽气,结果表明NEGP对H2具有较大的抽速,但对碳氢类化合物(如CH4)和惰性气体几乎没有抽速。用NEGP对XHV校准室连续抽气72h后,XHV校准室内的压力从8.34×10-9Pa下降到9.12×10-10Pa。不锈钢XHV校准室内的残余气体成分中大量的CO和CO2主要来自于四极质谱计。     

锆铝吸气泵的设计计算及性能试验研究

一、前言 锆铝吸气泵是近十年发展起来的用一种非蒸散性吸气材料(84%Zr—16?合金)在不同温度下吸附活性气体的新型泵。此泵结构简单、体积小、造价低、操作安全可靠、维修方便、清洁无油,然而对活性气体尤其是对H2具有很大的抽气能力。但这种泵不能抽惰性气体。 锆铝吸气泵对H2及其同位素的吸气作用是可逆的,对H2抽速在10-10～10-2托这样宽的压强范围内几乎保持恒定(1)。对其他活性气体,如CO、CO2、O2、N2、H2O的吸气是以稳定的化合物扩散到吸气剂体内,则存在着饱和寿命问题,其抽速在低于10-5托压强,400 工作温度下几乎恒定到饱和为…     

TiZrV吸气剂薄膜吸气性能的研究

TiZrV合金在180℃下加热24 h即可激活,是迄今发现的激活温度最低的非蒸散型吸气剂,已在粒子加速器领域得到应用。采用直流磁控溅射法在不锈钢管道内壁获得了TiZrV薄膜,并研究了薄膜对CO和H2的吸气性能。在200℃下加热24 h后TiZrV对CO和H2的抽速分别为0.23和0.02 L.s-1.cm-2,吸气容量分别为6.8×10-5和6.6×10-2Pa.L.cm-2,且随着激活温度和时间的增加,吸气性能会有所提高。     

燃料气系统计量补偿方法探讨

炼油装置生产和消耗的燃料气是一种混合气体。混合气体中主要含有H2、CH4、C2H6、C2H4、C3H8、C3H6、C4H10、C4H8、C5H12、CO、CO2、H2S、空气等气体,比起单一气体的流量计量较为复杂。在石化企业中．日常的燃料气平衡采用的是质量平衡体系．所以不仅要求体积流量准确,而且要求混合密度计算准确。     

H_2S/CO_2环境中CO_2,pH值和Cl~-对P110套管钢电化学腐蚀的影响

针对目前高含H2S和CO2环境井下管材电化学腐蚀研究不深入的现状,采用动电位扫描技术分析了在H2S/CO2环境中环境腐蚀影响因素(CO2,pH值和Cl-)对P110套管钢电化学腐蚀行为的影响.在溶解H2S和CO2且pH=2.7的含Cl-溶液中,当混合气体中CO2含量分别为17%,34%,50%时,腐蚀电流密度(Jcorr)分别为0.328 49,0.295 73,0.237 09 mA/cm2,在含50%H2S环境中,腐蚀电流密度为0.272 89mA/cm2.与单一含H2S腐蚀环境相比,在酸性环境中CO2促进金属腐蚀,而在近中性环境中,CO2抑制金属腐蚀.在含Cl-溶液中,pH值降低,Jcorr,增加,而在不合Cl-溶液中,pH值降低,Jcorr降低.在pH=2.7的溶液中,当Cl-存在时,Jcorr提高;而在pH=5.9溶液中,当Cl-存在时Jcorr降低.     

HL-2M内置式低温泵基于DSMC方法的抽速计算

作为托克马克装置HL-2M的大型低温泵,必须确保其具有足够的抽速和较好的抽气性能。通过直接模拟蒙特卡洛方法的研究表明,HL-2M内置式低温泵在高真空分子流条件下的对H2的抽速为51.29 m~3/s,对He的抽速为24.94m~3/s,对D_2的抽速为38.04m~3/s;裸泵与带有偏滤器结构的抽速对比表明,偏滤器的结构使得低温泵的抽速下降很多,应该在允许的条件下,进一步优化偏滤器的结构;通过对粘滞系数的变化得知,真空泵的抽速受粘滞系数的变化影响较大;而对整个抽气过程的动态评估结果表明,低温真空泵具有较好的响应时间,能够满足实验的需求。     

微型复合溅射离子泵的设计研究

本文介绍了一种非蒸散型吸气剂（NEG）与微型溅射离子泵（SIP）集成构成的微型复合溅射离子泵。测试结果表明，当吸气剂激活后，复合泵的抽速达到0．45L／8，比未加吸气剂的同型溅射离子泵抽速提高了28％。该复合泵使真空器件的真空维持效果良好，可广泛应用于中小型的密闭真空器件中。     

KATRIN NEG pumping concept investigation

The Karlsruhe Tritium Neutrino experiment (KATRIN) is going to use a very large electro-static tandem spectrometer to measure the electron spectrum from the tritium beta decay, where several kilometers of non-evaporable getter (NEG) strips (type ST707) are to be used to achieve the UHV requirements. Different geometrical configurations of the NEG strips have been studied by Monte Carlo simulations. It is shown that the resulting pumping speed of the getter pumps will allow to get a pressure below 10⁻¹¹ mbar in the huge vessel with a volume of 1400 m³. By systematic assessment of the statistics of the pumping surfaces, it could be demonstrated that the design is sound.     

Outgassing measurement of an LHC collimator and estimation for the NEG performances

The outgassing rate of the collimators in the Large Hadron Collider (LHC) at CERN has an important role for the life-time of the Non-Evaporable Getter (NEG), and an accurate analysis allows the definition of future activities, like NEG vacuum activation. For these reasons, both, total outgassing rate and gas composition of a secondary collimator have been measured in the laboratory. The outgassing rate decreases by about two orders of magnitude by after bake-out and moreover, repeated bake-out further reduced the outgassing rate. The gas transmission through the NEG coated beam pipes and the resulting pressure distributions near the collimator were also measured in a dedicated setup. It is found that the main gas component after just 2 m of NEG coated beam pipe is CH₄ due to the extreme pumping speed of NEG for the other gases. Large amount of outgassing for H₂ and carbon related molecules are released when moving the collimator jaws. It is found that the NEG is very effective even in such case with large gas load.     

TiZrV吸气剂薄膜的性能研究

采用独立设计组装的磁控溅射装置完成了对不锈钢管道的镀TiZrV薄膜处理。对TiZrV薄膜的相关性能包括二次电子产额(SEY)、光致解吸(PSD)产额和吸气性能进行了研究。在200℃下加热2h后TiZrV的SEY有所下降,峰值由2.03降到1.55。不锈钢真空室在镀TiZrV薄膜处理后其PSD效应显著降低,在200℃下加热24h后,各气体的PSD产额与初始值相比可降低两个量级左右。TiZrV薄膜对CO和H2有较好的吸气效果,相同激活条件下对CO的抽速比H2高一个量级,吸气容量则较之低两个量级;另外,随着加热温度的提高和时间的延长,其吸气能力会有所提高。     

Effect of coating morphology on the electron stimulated desorption from Ti-Zr-Hf-V nonevaporable-getter-coated stainless steel

The electron stimulated desorption (ESD) was studied for quaternary Ti-Zr-Hf-V alloy coated stainless steel samples with different surface structures: dense on one sample and columnar on another. The ESD yields were measured as a function of electron accumulated dose up to ∼10²³ e⁻/m² or greater and three different NEG coating activation temperatures: 150, 180 and 250 °C. After each ESD experiment the samples were saturated with a mixture of H₂, CO and CO₂. Both samples depicted lower ESD yields for all desorbed species compared to a ternary Ti-Zr-V alloy. It was also shown that although the columnar NEG coating demonstrated better pumping properties and, for NEG activated at 150 °C, lower initial ESD yields, the higher activation temperature may result in a significant H₂ yield increase with dose for the columnar NEG coating. This effect was demonstrated for the first time and should be considered for application in particle accelerators.     

A novel route to compact,high performance pumping in UHV–XHV vacuum systems

The need to miniaturize and reduce the footprint of vacuum systems is increasing in industrial and research devices, such as portable analyzers, electron microscopes, surface science systems, semiconductor tools or particle accelerators. This poses serious challenges to the pumping groups in term of design, space constraints and weight. In this paper a novel type of combination pump is introduced, which integrates into a single device a Non Evaporable Getter (NEG) element with a small sputter ion pump (SIP). In this design, the NEG element acts as the main vacuum pump to remove hydrogen and the active gases, leaving to the SIP the ancillary task of pumping inert gases, which are not sorbed by the NEG. This approach, which develops large pumping speeds in a compact package, is helpful to achieve appropriate vacuum conditions in laboratory equipment. It can also improve and simplify the design of complex vacuum systems and apparatuses.     

Measuring volume ratios of vacuum vessels using non-evaporable getters

Several methods have been used in vacuum metrology for volume determination. Volume ratios can be determined by different gas expansion methods, which were primarily developed for the precise determination of expansion ratios in static expansion systems. Measurements of the volume ratios using the gas expansion methods below 10⁻² Pa are influenced by outgassing from chamber walls. To reduce outgassing in the expansion chambers during measurements at low pressures, we have installed non-evaporable getter (NEG) pumps, which pump hydrogen and other active gases but have a negligible pumping speed for inert gases. The volume ratio of two chambers of an experimental static expansion system has thus been measured using the inert gases argon, helium and krypton. The obtained results were compared with the measurements without the use of an NEG pump. Measurements of the pressure ratios were performed with a spinning rotor gauge (SRG).     

溅射离子泵对N2和CO抽速的理论计算

根据潘宁放电机理，导出溅射离子泵抽速的理论公式。讨论了抽速对各种放电参数的依赖关系。计算了离子泵对Ｎ２和ＣＯ的抽速。计算结果和实验测试以及经验公式的结果有较好的符合。     

The influence of ionization gauges on gas flow measurements

The pumping speed of BA-gauges using W (thoriated Ir) filaments was measured. It was found to be 0.28 (0.12) litres/s for H₂, 1.5 (0.5) litres/s for O₂; no pumping speed could be detected for CO. Outgassing rates obtained after bakeout for various samples were measured by means of the throughput method. In this work the data obtained are corrected for gauge induced gas reactions.