Effect of methane content and the oscillating electric field between electrodes on atmospheric Ar/methane plasma jet and DLC coating deposition

In this work, the effects of the methane gas flow and the internal oscillating electric field between electrodes on radio-frequency(RF) atmospheric pressure argon/methane plasma jet and process of diamond-like carbon(DLC) film deposition have been investigated. Properties of RF atmospheric Ar/methane plasma jet such as active species density, length, electron temperature,appearance and ionization process of argon/methane plasma jet are changed due to the changing of methane flow content and electric field vector and its gradient. With increasing methane flow,the formation of C2 hydrocarbon and CH band content is decreased because injected electrical energy to a mixture of Ar/methane gases is insufficient to stabilize the ionization process of methane gas and the electrical-chemical reaction rate is decreased. With shortening the gas gap between two electrodes, electric field strength and its gradient are increased leading to more energy injection to the electron. Electrical-chemical reactions are strengthened leading to increasing the CH band content. These phenomena introduce the Ar/methane plasma jet in different modes causing to deposit the DLC film with different structures and properties. With using quartz glass and alumina ceramic as dielectric barriers tubes, RF atmospheric pressure Ar/methane plasma jet has been used to deposit DLC coating in different modes. Increasing methane content and shortening the gas gap leads to decreasing sp3 bonded content and the quality of the deposited film.     

用于ICF的非晶SiC微球制备及微观结构研究

以四甲基硅烷、反式二丁烯和氢气为工作气源,采用化学气相沉积-高温热解法成功制备了壁厚约21μm的非晶SiC微球。利用能量色散X射线光谱仪、X射线光电子能谱仪、X射线衍射仪、Raman光谱仪、扫描电子显微镜、白光干涉仪和X射线照相机对SiC微球的化学成分、结晶状态、表面形貌与粗糙度以及密度与球形度等进行了测量和分析。结果表明:在无氧环境下,通过450~900℃的高温热解及致密化可将在聚α甲基苯乙烯芯轴上沉积的掺硅碳氢聚合物涂层转变成致密的SiC微球。SiC微球呈非晶态,其C/Si原子比约为1.3,主要含有C—Si键和C=C键,微观结构呈无规则状且颗粒分布均匀,密度、球形度和壁厚均匀性分别为2.62 g/cm~3、99.8%和96.8%。     

Influence of the gassing materials on the dielectric properties of air

Influence of the gassing materials, such as PA6, PMMA, and POM on the dielectric properties of air are investigated. In this work, the fundamental electron collision cross section data were carefully selected and validated. Then the species compositions of the air–organic vapor mixtures were calculated based on the Gibbs free energy minimization. Finally, the Townsend ionization coefficient, the Townsend electron attachment coefficient and the critical reduced electric field strength were derived from the calculated electron energy distribution function by solving the Boltzmann transport equation. The calculation results indicated that H_2O with large attachment cross sections has a great impact on the critical reduced electric field strength of the air–organic vapor mixtures. On the other hand, the vaporization of gassing materials can help to increase the dielectric properties of air circuit breakers to some degree.     

The Structure and I-V Property of a-C:F Thin Film

1. IntroductionWith the development of ultralarge-scale integration (ULSI), multilevel interconnections have be-come increasingly important. Interconnection delaycaused by parasitic caPacitance has attracted moreattention than gate delay. Low- die le ct riccon st antmaterials are required to reduce this delay and improve the swiching performance [1~41.An a-C:F thin film can be used as an ideal in-terlayer dielectric material fOr its low dielectric con-stant, good elecrtic proPerty, good ga…     

用于CSNS反角白光中子源的双屏栅电离室设计及性能研究

为测量中国散裂中子源（China Spallation Neutron Source, CSNS）反角白光中子源150 keV以下能区飞行时间法中子能谱,研制基于¹⁰B(n, α)⁷Li和⁶Li(n, t)α核反应的双屏栅电离室,采用薄窗和薄底衬的结构设计。通过Garfield++、SRIM和Simcenter Magnet Electric程序对屏栅电离室的工作气体、极间距和电场分布等工作参数进行模拟设计,并采用α源及CF₄、P10、90%Ar-10%CO₂三种气体对电离室进行性能参数测试。结果表明,选定电子漂移速度快、扩散系数小,以及阻止本领大的CF4作为CSNS/Back-n束上测试工作气体,阴极-栅极和栅极-阳极间距分别为20 mm和5 mm。屏栅电离室收集区74 mm范围内是电场均匀区,场强的相对偏差≤0.03%;性能测试结果表明,工作气体为CF₄时,电离室对²³⁹Pu/²⁴¹Am/²⁴⁴Cm混合α面源具有很好的能量分辨,最佳能量分辨率为2.4%@5.48 MeV。对比平板型电离室和硅微条探测器的测量结果,验证了本工作研制的屏栅型电离室的能量分辨优势。     

Reduction of the Electron Capture Cross-Section for Protons in Hydrocarbon Cases

The total electron capture cross section of 0.8 - 3.0 MeV protons in various hydrocarbon gases (CHn - C4H , n = 2 - 8) has been measured. We find that the electron capture cross section per carbon atom decreases as the number of carbon atoms per molecule is increased. This reduction amounts to ~7% for 3 MeV protons and is ~ 25% for 0.8 MeV protons. We find no significant change in the electron capture cross section for carbon as the number of hydrogen atoms per molecule is increased. The observed variations in the cross section can be reproduced by assuming that post-collision-interactions destroy the required velocity match between projectile and electron.     

Investigation on the Dielectric Properties of CO2 and CO2-Based Gases Based on the Boltzmann Equation Analysis

In this paper,the dielectric properties of CO_2,CO_2/air,CO_2/O2,CO_2/N_2,CO_2/CF_4,CO_2/CH_4,CO_2/He,CO_2/H_2,CO_2/NH_3 and CO_2/CO were investigated based on the Boltzmann equation analysis,in which the reduced critical electric field strength(E/N)crof the gases was derived from the calculated electron energy distribution function(EEDF) by solving the Boltzmann transport equation.In this work,it should be noted that the fundamental data were carefully selected by the published experimental results and calculations to ensure the validity of the calculation.The results indicate that if He,H_2,N_2 and CH_4,in which there are high ionization coefficients or a lack of attachment reactions,are added into CO_2,the dielectric properties will decrease.On the other hand,air,O2,NH_3 and CF_4(ranked in terms of(E/N)_(cr) value in increasing order) have the potential to improve the dielectric property of CO_2 at room temperature.     

微波非热效应对有机硫化合物结构的影响

为探究微波辐照脱除煤中有机硫的作用机理以及影响程度,通过核磁共振氢谱、红外光谱和激光共聚焦显微拉曼光谱技术,研究了微波非热效应对有机硫模型化合物结构性能的影响。红外光谱测试说明,微波辐照有机硫化合物存在非热效应并影响化学键的键能分布、基团的振动强度和稳定性,但仅限于分子的极化机制,不会破坏分子中原有的化学键也不会生成新的化学键和基团;核磁共振氢谱揭示非热效应影响了模型化合物分子内部的电子云密度分布和磁环境,对含硫化合物产生的双重极化作用既可改变微观的电子或原子极化,也可改变分子固有偶极矩的取向;显微激光拉曼光谱证明非热效应可有效极化含硫键,使之振动强度减弱,从而有助于有机硫的微波辐射脱除。     

地面放射性异常引起电离层扰动的计算研究

地面的放射性主要来源于空间辐射、地壳放射性元素衰变和人工核活动等,地面放射性可引起地表电场的变化,地表电场变化的区域和强度达到一定的条件后可引起电离层的扰动。基于LAIC电场机制假设,本文从地面放射性引起空气电离开始推导地表大气电导率变化、地面垂直电场至电离层底部传导过程,根据临界电场理论计算地面大气垂直电场、大气附加电流密度以及电离层准静态电场的电势分布,最后通过格林函数法求解得到电离层中水平电场的分布。建立了基于地面放射性活度的地表大气电导率公式,改进了地表异常电场传播到电离层的计算过程,给出了电离层电场扰动的计算公式。利用氡和地面电场仪的实例观测数据对地面放射性异常引起的电离层扰动的计算过程进行了验证,理论计算得到的地面电场和电离层扰动的结果与实际测量结果基本一致。     

Simulation and Investigation of Deuteron Trajectories in the Main Electromagnetic Field of AVF Cyclotron

The paper describes Trajectories of Deuteron, equilibrium orbits and stability of deuterons on a four sectors of tight design giving 15 MeV deuterons. So, we solved differential equations on Electromagnetic fields in central region of Cyclotron30 by paying attention to boundary value, electric and magnetic field; Then, we show the scheme of position-time and simulated trajectories of deuteron ion in these regions by programming in C++. We could get good results like energy, period of time that is comparable with a real one. We also calculate radial and vertical changes of magnetic field of Cyclone-30 by multi degree and Fourier functions. Based on measured main magnetic field by Ion Beam Application, we calculated coefficients of these functions and then investigated equilibrium orbits and stability includes Betetatron frequency, radial and vertical motion and momentum, etc. Advanced graphical tools of MATLAB give good visualization features to created models.     

Diagnosing the Fine Structure of Electron Energy Within the ECRIT Ion Source

The ion source of the electron cyclotron resonance ion thruster(ECRIT) extracts ions from its ECR plasma to generate thrust, and has the property of low gas consumption(2 sccm,standard-state cubic centimeter per minute) and high durability. Due to the indispensable effects of the primary electron in gas discharge, it is important to experimentally clarify the electron energy structure within the ion source of the ECRIT through analyzing the electron energy distribution function(EEDF) of the plasma inside the thruster. In this article the Langmuir probe diagnosing method was used to diagnose the EEDF, from which the effective electron temperature, plasma density and the electron energy probability function(EEPF) were deduced. The experimental results show that the magnetic field influences the curves of EEDF and EEPF and make the effective plasma parameter nonuniform. The diagnosed electron temperature and density from sample points increased from 4 eV/2×10~(16)m~(-3) to 10 eV/4×10~(16)m(-3) with increasing distances from both the axis and the screen grid of the ion source. Electron temperature and density peaking near the wall coincided with the discharge process. However, a double Maxwellian electron distribution was unexpectedly observed at the position near the axis of the ion source and about 30 mm from the screen grid. Besides, the double Maxwellian electron distribution was more likely to emerge at high power and a low gas flow rate. These phenomena were believed to relate to the arrangements of the gas inlets and the magnetic field where the double Maxwellian electron distribution exits. The results of this research may enhance the understanding of the plasma generation process in the ion source of this type and help to improve its performance.     

Correlation of III/V semiconductor etch results with physical parameters of high-density reactive plasmas excited by electron cyclotron resonance

Reactive ion etching is the interaction of reactive plasmas with surfaces. To obtain a detailed understanding of this process, significant properties of reactive composite low-pressure plasmas driven by electron cyclotron resonance (ECR) were investigated and compared with the radial uniformity of the etch rate. The determination of the electronic properties of chlorine-and hydrogen-containing plasmas enabled the understanding of the pressure-dependent behavior of the plasma density and provided better insights into the electronic parameters of reactive etch gases. From the electrical evaluation of I(V ) characteristics obtained using a Langmuir probe, plasmas of different compositions were investigated. The standard method of Druyvesteyn to derive the electron energy distribution functions by the second derivative of the I(V ) characteristics was replaced by a mathematical model which has been evolved to be more robust against noise, mainly, because the first derivative of the I(V ) characteristics is used. Special attention was given to the power of the energy dependence in the exponent. In particular, for plasmas that are generated by ECR with EM modes, the existence of Maxwellian distribution functions is not to be taken as a self-evident fact, but the bi-Maxwellian distribution was proven for Ar-and Kr-stabilized plasmas. In addition to the electron temperature, the global uniform discharge model has been shown to be useful for calculating the neutral gas temperature. To what extent the invasive method of using a Langmuir probe could be replaced with the non-invasive optical method of emission spectroscopy, particularly actinometry, was investigated, and the resulting data exhibited the same relative behavior as the Langmuir data. The correlation with etchrate data reveals the large chemical part of the removal process—most striking when the data is compared with etching in pure argon. Although the relative amount of the radial variation of plasma density and etch rate is approximately ±5%, the etch rate shows a slightly concave shape in contrast to the plasma density.     

低能电子辐照对环氧树脂性能的影响

为了研究低能电子辐照对环氧树脂的体积电阻率、邵氏硬度、拉伸强度和官能团结构的影响,本文在电子辐照能量为30 keV,注量率1×10¹¹ cm^-2•s^-1,总注量为1.6×10¹⁴ cm^-2,真空度10^-6 Pa条件下,结合国家标准对辐照前、后环氧树脂材料的机械性能和结构进行表征。结果表明,辐照后环氧树脂材料的体积电阻率、邵氏硬度、拉伸强度等宏观物理性能均有下降。傅里叶红外光谱图显示环氧树脂主要官能团强度降低,产生的•H、•OH等自由基与聚合物分子上的羟基与氢结合。研究结果对环氧树脂材料在辐射环境中的使用具有重要意义。     

Correlation of Ⅲ/Ⅴ semiconductor etch results with physical parameters of high-density reactive plasmas excited by electron cyclotron resonance

Reactive ion etching is the interaction of reactive plasmas with surfaces. To obtain a detailed understanding of this process, significant properties of reactive composite low-pressure plasmas driven by electron cyclotron resonance(ECR) were investigated and compared with the radial uniformity of the etch rate. The determination of the electronic properties of chlorine-and hydrogen-containing plasmas enabled the understanding of the pressure-dependent behavior of the plasma density and provided better insights into the electronic parameters of reactive etch gases. From the electrical evaluation of I(V) characteristics obtained using a Langmuir probe,plasmas of different compositions were investigated. The standard method of Druyvesteyn to derive the electron energy distribution functions by the second derivative of the I(V)characteristics was replaced by a mathematical model which has been evolved to be more robust against noise, mainly, because the first derivative of the I(V) characteristics is used. Special attention was given to the power of the energy dependence in the exponent. In particular, for plasmas that are generated by ECR with EM modes, the existence of Maxwellian distribution functions is not to be taken as a self-evident fact, but the bi-Maxwellian distribution was proven for Ar-and Kr-stabilized plasmas. In addition to the electron temperature, the global uniform discharge model has been shown to be useful for calculating the neutral gas temperature. To what extent the invasive method of using a Langmuir probe could be replaced with the noninvasive optical method of emission spectroscopy, particularly actinometry, was investigated,and the resulting data exhibited the same relative behavior as the Langmuir data. The correlation with etchrate data reveals the large chemical part of the removal process—most striking when the data is compared with etching in pure argon. Although the relative amount of the radial variation of plasma density and etch rate is approximately ?5%, the etch rate shows a slightly concave shape in contrast to the plasma density.     

基于GEM工艺的裂变时间投影室性能模拟研究

基于GEM工艺的裂变时间投影室具有探测效率高和空间分辨率高的特点,可实现裂变产物的多参量测量。本文主要研究基于GEM工艺的裂变时间投影室在不同条件下的测量精度,使用Garfield++软件计算得到裂变时间投影室中不同的裂变产物质量数测量误差约为4～6 u,并通过时间信息的径迹重建研究了裂变碎片在不同工作气体中的角度分辨。研究发现,电子漂移时间长的工作气体中,裂变产物具有更好的角度分辨,并可依此在实验中选择合适的工作气体、气压和漂移电场强度来进行裂变碎片的测量。     

Effects of the electric field at the edge of a substrate to deposit a Ø100 mm uniform diamond film in a 2.45 GHz MPCVD system

In this study, uniform diamond films with a diameter of 100 mm were deposited in a 15 kW/2.45 GHz ellipsoidal microwave plasma chemical vapour deposition system. A phenomenological model previously developed by our group was used to simulate the distribution of the electric strength and electron density of plasma. Results indicate that the electric field in the cavity includes multiple modes, i.e. TM02 and TM03. When the gas pressure exceeds 10 kPa, the electron density of plasma increases and plasma volume decreases. A T-shaped substrate was developed to achieve uniform temperature, and the substrate was suspended in air from Ø70 to 100 mm, thus eliminating vertical heat dissipation. An edge electric field was added to the system after the introduction of the T-shaped substrate. Moreover, the plasma volume in this case was greater than that in the central electric field but smaller than that in the periphery electric field of the TM02 mode. This indicates that the electric field above and below the edge benefits the plasma volume rather than the periphery electric field of the TM02 mode. The quality, uniformity and surface morphology of the deposited diamond films were primarily investigated to maintain substrate temperature uniformity. When employing the improved substrate, the thickness unevenness of the Ø100 mm diamond film decreased from 22% to 7%.     

A New Grade Carbon Black Produced by Thermal Plasma Process

This paper presents a new route about producing carbon black,by wich the natural gas cracking is carried out in the absence of oxygen thanks to an electric energy supply externally given by a plasma jet.The carbon black produced by this process has a narrow size distribution and a small average diameter of 38nm as well as a highly branched aggregate.The higher DBP value of 1.40ml/g shows it should be a high structure carbon black.The FTIR spectra shows that there are lots of aromatic c-c bonds and a large amount of nitrogen-coutaining functional groups on the carbon blacks surface,such as-NH,-CN as we3ll as -CH,-OH,-COOH groups.     

800kV高压传输装置的电场数值计算

介绍了800kV高压传输装置的组成和结构安排；对在SF6绝缘气体环境中的电缆终端进行了电场数值计算，并对计算结果进行了分析；最后得出结论，电缆终端的场强设计是可靠的。     

碳掺杂氮化硼纳米管吸附气体小分子的DFT计算

采用密度泛函理论研究了氮化硼纳米管(Boron nitride nanotubes,BNNTs)及碳掺杂氮化硼纳米管对O2、NO2、F2气体小分子的气敏特性。计算了三种气体小分子吸附在氮化硼纳米管及碳掺杂氮化硼纳米管表面不同位置时的吸附能、相互作用距离,同时还计算得到了气体分子分别吸附在碳掺杂BNNTs不同位置时的电子态密度。研究结果表明,氮化硼纳米管对O2、NO2、F2气体分子比较敏感,碳掺杂氮化硼纳米管可以明显地改变其表面的化学反应活性,增强气体分子与氮化硼纳米管之间的相互作用。