铬及铍表面辉光放电清洗的研究

本文对He辉光放电清洗后的铬（Cr）表面杂质去除情况和铍（Be）样品真空出气量变化进行了实验研究。使用场发射扫描电镜和表面质量测量仪对比观察了不同放电参数处理后的Cr样品表面，结果显示在放电功率为200～300W、放电室压强为1～10Pa、清洗时间为10-20min时可较好地清除表面杂质和降低表面粗糙度；对辉光放电处理前后Be样品出气情况的实验对比结果显示，清洗后1h内总出气量约降为清洗前的1／6。     

高分辨四极质谱计在HL-2A装置上的应用

将具有分辨氦(He)和氘(D2)能力的高分辨四极质谱计安装到HL-2A托卡马克装置上,同时送入氦气和氘气,得到了质谱计可分辨的最小He+/D2+峰值比.分别对真空室在辉光放电清洗前后、不同等离子体放电次数的氢同位素和氦进行测量,观察到四种工况下质谱峰m/q=4的主要成分为D2+,He+只在辉光放电清洗中作为工作气体引入.向真空室送入氘气后,比较了由分子泵和低温泵抽气的质谱情况.分压强的测量结果表明低温泵对氘气的抽速大于分子泵约18％.实验结果初步验证了高分辨四极质谱计应用于托卡马克装置可靠真空检漏和残余气体成分精确分析的可行性,并为托卡马克装置抽气泵的选型提供了依据.     

等离子体装置器壁的直流和高频辉光放电清洗

本文描述直流辉光放电、10兆周高频加直流辉光放电原理和实验方法。给出了几种工作气体(H_2,He,Ar,N_2和空气)在30升圆筒形真空室中进行直流辉光放电、直流加高频辉光放电时起辉和灭辉气压随外加电压变化实验结果。实验表明,对于几百伏外加电压下H_2,He,Ar气可在10~(-1)帕气压下起辉;可以维持到10~(-2)帕气压才灭辉。几百伏直流电压附加10兆周高频电源可使起辉气压和灭辉气压下降几倍。空气和氮气比氢更易起辉。对HT-6M托卡马克真空室进行了几十小时常温和100℃中温烘烤条件下辉光放电清洗效果比较,表明边烘烤边辉光放电对水的清洗作用更好。实验由四极质谱仪监测,并用真空传输装置将样品传送到俄歇谱仪中分析放电前后表面成分的变化。对放电有关问题进行了讨论。     

HL-2A装置直流辉光自动调节控制系统北大核心CSCD

直流辉光放电清洗的主要作用是去除HL-2A装置内的低Z杂质C、O,以及放电期间所产生的残余气体和杂质。介绍了直流辉光放电自动调节控制系统。在辉光放电过程中,实现了真空室工作气体气压和放电电压的自动调节和信号采集。本文描述了系统的设计原理,控制方案和系统实现后的具体应用效果。直流辉光放电系统的性能得到了提高,放电电流稳定性得到了显著提高,放电电压的控制精度改善为1%FS,系统从启动到稳定运行状态的时间小于40 s,HL-2A装置的清洗效率也明显获得改善。     

HL-2A装置直流辉光自动调节控制系统

直流辉光放电清洗的主要作用是去除HL-2A装置内的低Z杂质C、O,以及放电期间所产生的残余气体和杂质。介绍了直流辉光放电自动调节控制系统。在辉光放电过程中,实现了真空室工作气体气压和放电电压的自动调节和信号采集。本文描述了系统的设计原理,控制方案和系统实现后的具体应用效果。直流辉光放电系统的性能得到了提高,放电电流稳定性得到了显著提高,放电电压的控制精度改善为1%FS,系统从启动到稳定运行状态的时间小于40 s,HL-2A装置的清洗效率也明显获得改善。     

用氧化还原反应气体清洗不锈钢超高真空系统

对粒子加速器和储存环的超高真空系统，消除其表面污染的标准方法是化学清洗、真空炉焙烧、辉光放电清洗及原位烘烤真空系统，本文介绍一种可替代辉光放电的清洗方法；用一氧化氮反应气体进行清洗，它已被用于处理几种不锈钢制作的加速器真空室，用ＮＯ气体处理的效果与其它方法相比，优于普通化学清洗和真空炉焙烧，完全可以和辉光放电清洗相比较，却避免了溅射情况下可能引起的表面损伤。     

超高真空下剩余气体分析的实验

本文叙述在钛溅射离子泵超高真空系统上利用小型180°磁质谱计(Zh-3型)所做的剩余气体分析的实验。系统采用全金属密封、带冷阱的机械泵预抽,通过有机溶剂的清洗和氮气辉光放电以及中温烘烤等处理获得超高真空。对系统的各压强下的气体成分以及B-A规的影响作了分析。根据实验结果,讨论了剩余气体成分对获得超高真空等影响。     

HL-1M装置的真空运行与质谱诊断

通过对 HL- 1M装置真空运行模式、真空运行参数、氦辉光放电清洗和硅化壁处理手段等的规范化 ,显著地改善了装置的真空壁出气、本底杂质浓度、托卡马克放电杂质出气比和再循环 ,成功地实现了高参数放电、长脉冲放电和装置暴露大气后快速恢复放电 ,并成功地为演证低混杂电流驱动、离子回旋共振加热、电子回旋共振加热、中性束注入、弹丸注入和分子束注入实验和升级等离子体运行等提供了良好的真空壁条件。描述了 HL- 1M装置真空系统、壁出气和再循环控制、质谱诊断和程序脉冲送气等方面的主要实验成果 ,并为 HL- 2 A装置的真空系统研制和运行提供了有益的参考     

气体放电等离子体及应用的研究进展

由于气体放电在材料处理、热核聚变、环境净化以及等离子体推力器等各个前沿科学领域中具有广泛的应用。为了推动气体放电及等离子体理论与应用技术的研究和发展,综述了近年来各种典型气体放电机理的发展。分析了直流辉光放电、介质阻挡放电、大气压辉光放电、电子回旋共振放电、容性耦合射频放电的国内外研究现状,最后介绍了气体放电等离子体的应用领域。     

光学太阳反射镜基底的辉光放电清洗

辉光放电清洗技术是一种用来改善膜层附着力的物理清洗方法。它是将基片浸没在含有化学活性气体辉光放电的等离子体中,使基片表面受到电子、离子和光子以及活性粒子的轰击、活化,从而达到清洗的目的。对于光学镀膜来说,目前大部分真空镀膜设备上的放电电极的安排是很不合理的。为此,重新设计并改进了辉光放电装置,通过放电清洗参数对清洗效果的实验研究,获得了最佳清洗工艺。经此工艺处理过的基片制备的光学太阳反射镜用胶带纸剥离法来检验膜层的附着力,结果表明,这种方法大大提高了膜层的附着力,其性能已完全能满足光学太阳反射镜在空间的使用要求。采用辉光放电清洗基片的光学太阳反射镜,其光学性能会受到少许影响。实验表明,它可使光学太阳反射镜的太阳吸收率增大0.002(石英玻璃型)和0.004(掺铈玻璃型)。为此,我们对因光学太阳反射镜光学性能改变而引起的卫星热控温升作了估算,对于石英玻璃型和掺铈玻璃型光学太阳反射镜这一温升仅分别为1.0℃～1.5℃和1.7℃～2.7℃。     

Glow discharge mass spectrometric analysis of atmospheric particulate matter

A direct current (dc) glow discharge mass spectrometer has been used to analyze atmospheric particulate matter. The sample preparation used is simple and time-saving. The air is sucked by a pump through a single-orifice impactor stage, in which the aerosols are impacted on a metal support, forming a central spot. This metal plate is directly used as a cathode in a dc glow discharge mass spectrometer. Evaluation of the sample loading and of the discharge parameters allowed us to optimize the signal intensity and to minimize its decrease, the latter being a consequence of its consumption by continuous sputtering in the discharge. The available aerosol analysis time could be prolonged to more than 3 h, a time span necessary to perform a multielement analysis using a magnetic sector instrument and long integration times. A NIST reference aerosol was measured to evaluate the quantitative analysis potential. The internal reproducibility was better than 10% RSD, and the limits of detection were estimated to be in the low ppm or sub ppm region. Even without the use of any standards or correction factors, glow discharge mass spectrometry could offer good semiquantitative results, based only on the use of an internal standard.     

Pulsed-gas glow discharge for ultrahigh mass resolution measurements with fourier transform ion cyclotron resonance mass spectrometry

A new pulsed-gas glow discharge (GD) source has been developed for use with an external ion source Fourier transform ion cyclotron resonance (FTICR) mass spectrometer. With pulsed argon gas introduction into the GD source, the gas load and pressure in the mass analyzer region were greatly reduced; this resulted in improved mass resolution. Mass resolution of greater than 1?450?000 (fwhm) has been achieved for Cu(+) ions from a brass sample, the highest reported for any type of GD mass spectrometer. The pulsed-gas GD source promises analytical usefulness for ultrahigh resolution measurements in GD mass spectrometry.     

Atmospheric pressure chemical ionization source. 1. Ionization of compounds in the gas phase

A novel chemical ionization source for organic mass spectrometry is introduced. This new source uses a glow discharge in the flowing afterglow mode for the generation of excited species and ions. The direct-current gas discharge is operated in helium at atmospheric pressure; typical operating voltages and currents are around 500 V and 25 mA, respectively. The species generated by this atmospheric pressure glow discharge are mixed with ambient air to generate reagent ions (mostly ionized water clusters and NO+), which are then used for the ionization of gaseous organic compounds. A wide variety of substances, both polar and nonpolar, can be ionized. The resulting mass spectra generally show the parent molecular ion (M+ or MH+) with little or no fragmentation. Proton transfer from ionized water clusters has been identified as the main ionization pathway. However, the presence of radical molecular ions (M+) for some compounds indicates that other ionization mechanisms are also involved. The analytical capabilities of this source were evaluated with a time-of-flight mass spectrometer, and preliminary characterization shows very good stability, linearity, and sensitivity. Limits of detection in the single to tens of femtomole range are reported for selected compounds.     

两种不同方法测定铑粉中杂质元素含量的对比

金属铑粉在汽车催化剂、气体传感器、生物医药、化工等领域有着非常广泛的应用,其纯度会直接影响产品的性能,因此准确测定铑粉中的杂质含量进而计算得出铑粉纯度数据至关重要。目前常用的铑粉杂质检测方法有电感耦合等离子体发射光谱法（ICP-AES）和辉光放电质谱法（GD-MS）,为比较二者的实际应用效果,通过六西格玛统计方法对两种检测方法得到的数据进行对比,并对有明显差异的结果进行原因分析和改善。     

Experimental and theoretical study of the role of the gas composition and plasma-surface interactions on the SnOx films stoichiometry prepared by DC magnetron reactive sputtering

In this paper, we have studied the tin oxide films deposition by DC magnetron reactive sputtering. We have investigated the discharge parameters such as discharge voltage and deposition rate and the discharge composition as a function of the input oxygen partial pressure. We have compared these results with the deposited films stoichiometry. In the constant current discharge mode, we observe, with increasing oxygen partial pressure, a decrease of the discharge voltage followed by a slight increase, and a drop of the deposition rate. For each experimental conditions, we measure the gas composition by mass spectrometry (glow discharge mass spectrometry mode and residual gas analysis mode (RGA)) and the deposited films stoichiometry by X-ray photoemission spectroscopy. The results are fitted by means of a model, taking into account the plasma-surface interactions. All the data are fitted by the same equation, with only four fitting parameters, namely the sticking-reaction coefficients of O and O₂ on Sn and SnO surfaces. Our results show that the main reaction is the reaction between the atomic oxygen and the metallic part (Sn) of the substrate. This reaction is characterized by a sticking coefficient value (α₁⁰) of 0.96.     

Liquid sample injection using an atmospheric pressure direct current glow discharge ionization source.

An atmospheric pressure DC glow discharge in helium has been used as an ionization source for organic samples introduced by liquid injection into atmospheric pressure ionization mass spectrometry (API/MS). The glow source operates typically in the range up to 1 mA of current at less than 1 kV, although the source can be operated up to a discharge current of 10 mA. Even at the high current used in this work, the protonated molecule, MH+, is observed with little or no fragmentation for many of the samples studied. The detection limits achieved for API glow discharge detection are typically in the low femtomole region for small organic molecules including small biological neurotransmitters, drugs, pesticides, phenylthiohydantoin-substituted amino acids, and explosives. A detection limit of approximately 2 pg has been achieved for tyramine with linear quantitation over at least 3 orders of magnitude. The sensitivity in these experiments has been further improved by optimization of the skimmer-interface system and the liquid injection/nebulization design.     

An in situ glow discharge cleaning method for the LEP vacuum system

The performance of the vacuum systems of present day electron storage rings is limited by synchrotron radiation induced gas desorption. A method to reduce the electron induced desorption yield (thought to be a measure of the radiation induced desorption) by glow discharge cleaning has been developed. Initial beam lifetimes for standard LEP operation (Large Electron Position Storage Ring) have been calculated based on measured electron stimulated desorption yields and two different proposed pumping systems. (One with distributed ion pumps, the other with distributed getter pumps). After bakeout, both systems would provide an initial beam lifetime of ～ 4 min. After a helium glow discharge for 3 h at 150°C (at 1.5 torr and with a discharge current of 0.7 A m^?1), a lifetime of ～6.7 h would be obtained in the ion pumped system as compared to ～1.7 h in the getter pumped version. Results obtained with Argon discharge proved to be inferior.     

Development and evaluation of a glow discharge microwave-induced-plasma tandem source for time-of-flight mass spectrometry

In this work, a new glow discharge, microwave-induced-plasma (GDMIP), tandem ion source was developed, characterized, and used in conjunction with time-of-flight mass spectrometry. This tandem source was designed to be simple and compact The GD and the MIP unit are independent and demountable, providing flexibility in tuning and operating. The microwave plasma can be formed with very low power (a few watts) and overlapped with the glow discharge. The discharge current increased with the addition of microwave discharge when the GD was operated in constant-voltage mode, and the amplitude of the current increase was found to be related to microwave power, discharge pressure, and sampling distance. With the addition of microwave discharge, significant signal enhancement was achieved under a discharge pressure of 2.0 Torr and a discharge voltage of 500 V with 2.0-mm sampling distance. Enhanced factors of analyte signals ranging from approximately 1 to nearly 10 could be obtained with MIP boosting, while no significant change in noise level was observed. This new tandem source provides improved performance in direct solid sample analysis.     

Controlling of material analysers of the GD-OES type with help of pump-down curves

Today, material analysis in industry and research centres is very often performed by the glow-discharge optical emission spectrometry (GD-OES), which allows an extraordinarily quick material analysis (average time of analysis: 2-5 min) and a determination mainly by the pumping time of the glow discharge source. The reliability of the analysis is, especially in the case of thin films (film thickness <100 nm), determined by the purity of the discharge gas and of the surface of the source and sample.We could reduce the ultimate pressure and increase the purity of the gas at the place of analysis by improving the dimensions and construction of the pumping set, and the conduction of the pumping and venting process of a given commercial spectrometer device.Moreover, an automatic and computer-aided evaluation of the pressure vs. time run in the source chamber can inform the user about possible leaks or contamination of inner surfaces. For this purpose, it is possible to use the control computer of commercial equipment and the data acquisition system of the GD-OES instrument. Thus, one can receive important hints from the p-t plot regarding the equipment and can start leak detection, cleaning of the source chamber or replacing of components in time.     

Quadrupole-based glow discharge mass spectrometer: Design and results compared to secondary ion mass spectrometry analyses

A design of quadrupole-based glow discharge mass spectrometer is briefly presented. A glow discharge occurs when a DC voltage (up to 3 kV) is applied between two electrodes in a cell filled with Ar at ∼1 hPa pressure. In this configuration, the sample acts as the cathode, and its surface (∼12 mm²) is sputtered by impacting Ar ions. The sputtered neutral atoms are ionised downstream in the plasma, and are extracted through a diaphragm to an energy filter and quadrupole spectrometer (6 mm rods) in high vacuum. The processes of sputtering and ionisation are separated, therefore reducing matrix effects.Preliminary results of elemental analysis of stainless steel, chromium-vanadium steel, Al-Mg-Cu and Armco alloys are presented. These results are compared to secondary ion mass spectrometry (SIMS) results obtained for the same set of samples using a 5 keV Ar⁺ ion beam and a quadrupole mass analyser (16 mm rods). The glow discharge mass spectrometry (GDMS) results allowed us to find SIMS relative sensitivity factors (RSF) for the analysed materials. Simple design and quick analysis time makes the new GDMS analyser an attractive tool in material technology.