Transport characteristics of space charge-dominated multi-species deuterium beam in electrostatic low-energy beam line

The transport characteristics of a space chargedominated multi-species deuterium beam consisting of D_1^+,D_2^+, and D_3^+ particles in an electrostatic low-energy beam line are studied. First, the envelope equations of the primary D_1^+ beam are derived considering the space charge effects caused by all particles. Second, the evolution of the envelope of the multi-species deuterium beam is simulated using the PIC code TRACK, with the results showing a significant effect of the unwanted beam on the transport of the primary beam. Finally, different injected beam parameters are used to study beam matching, and a new beam extraction system for the existing duoplasmatron source is designed to obtain the ideal injected beam parameters that allow a D_1^+ beam of up to 50 m A to pass unobstructed through the electrostatic low-energy beam transport line in the presence of an unwanted(D_2^+, D_3^+)beam of 20 m A; at the same time, distortions of the beam emittance and particle distributions are observed.

Electrostatic Discharge Effects on the High-voltage Solar Array

A certain number of charges are deposited on the surface of high-voltage solar array because of effects of space plasma,high-energy charged particles,and solar illumination,hence the surface is charged.Phenomena of electrostatic discharge(ESD) occur on the surface when the deposited charges exceed a threshold amount.In this paper,the mechanism of this ESD is discussed.The ground simulation experiment of the ESD using spacecraft material under surface charging is described,and a novel ESD protecting method for high-voltage solar array,i.e.an active protecting method based on the local strong electric field array is proposed.The results show that the reversal potential gradient field between the cover surface and the substrate materials of high-voltage solar array is a triggering factor for the ESD on the array.The threshold voltage for the ESD occurring on the surface is about 500 V.The charged particles could be deflected using the electric field active protecting method,and hence the ESD on the surface is avoided even when the voltage on the conductor array increases to a certain value.These results pave the way for further developing the protecting measures for high-voltage solar arrays.

Simulation of high-intense beam transport in electrostatic accelerating column

An electrostatic accelerating column was designed and fabricated by Lanzhou University for an intense DT/D-D neutron generator. In order to achieve a neutron yield of 5.0 × 10^(12)n/s, a deuteron beam of 30 mA,accelerated to 400 kV, and transported in the electrostatic accelerating column smoothly are required. One particle-in-cell code BEAMPATH was used to simulate the beam transport, and the IONB 1.0 code was used to simulate the intense beam envelopes. Emittance growths due to space charge effect and spherical aberration were analyzed. The simulation results show that the accelerating column can transport deuteron beam of 30 mA smoothly and the requirement for the neutron generator is satisfied.

卫星柔性热控薄膜材料充放电效应试验

针对柔性热控薄膜材料导电/绝缘多层复合、微纳尺寸厚度的结构特点,采用10~70 KeV电子辐照的方法开展了kapton基二次表面镜薄膜材料充放电特性的测试试验,获得了表面充电电位、静电放电频次等关键参数,并采用蒙特卡罗方法研究了辐照电子在多层薄膜材料内的输运规律。研究结果表明由于kapton基二次表面镜薄膜结构的特殊性,当辐照电子能量为10 KeV时未发生静电放电现象,随着电子能量不断增加,薄膜材料的表面充电电位幅值与静电放电频次呈先上升后下降的变化规律,且在电子能量为25 KeV时空间充放电效应最为显著。

空间电源低气压放电的相关问题研究

随着航天技术的快速发展,空间电推进、空间电子束焊接、空间通信、深空探测等空间任务对空间电源的电压等级和功率等级要求逐渐提高。由于空间电源输出电压等级的提高,电子产品在空间环境中的低气压放电问题逐渐显现。根据气体电介质的击穿理论,空间中低于大气压的环境意味着气体击穿电压水平比在大气环境中低得多,当达到一定的阈值电场强度时,电场将加快电荷载流子的运动,并最终发生击穿或闪络。针对空间低气压放电问题进行了调研、理论分析和静电场仿真,总结出现阶段适合空间电源应用的低气压放电理论,为空间高压电源及空间电源系统的发展打下基础。

浅析静电喷涂工艺参数中的距离要点设定及确认

工艺参数的调整对自动静电喷涂影响较大,而工艺参数中的距离参数是最容易受到忽视的一个参数,在不同的喷涂条件下,合理的距离参数可提高涂料上漆率,避免涂料浪费,降低对环境的污染。

Space Materials Science in China:Ⅱ.Ground-based Researches and Academic Activities

Activities of space materials science research in China have been continuously supported by two main national programs.One is the China Space Station(CSS)program since 1992,and the other is the Strategic Priority Program(SPP)on Space Science since 2011.In CSS plan in 2019,eleven space materials science experimental projects were officially approved for execution during the construction of the space station.In the SPP Phase Ⅱ launched in 2018,seven pre-research projects are deployed as the first batch in 2018,and one concept study project in 2019.These pre-research projects will be cultivated as candidates for future selection as space experiment projects on the recovery of scientific experimental satellites in the future.A new apparatus of electrostatic levitation system for ground-based research of space materials science and rapid solidification research has been developed under the support of the National Natural Science Foundation of China.In order to promote domestic academic activities and to enhance the advancement of space materials science in China,the Space Materials Science and Technology Division belong to the Chinese Materials Research Society was established in 2019.We also organized scientists to write five review papers on space materials science as a special topic published in the journal Scientia Sinica to provide valuable scientific and technical references for Chinese researchers.

粒子束空间传输影响因素及应对方法

全面分析了初始束流分布、发散度、能散度以及地磁场对粒子束空间传输的影响情况,并针对束流长距离传输的静电扩散和地磁偏转效应进行了数值建模及定量的数值仿真研究。结果表明,对于固定束流能量、流强粒子束,可通过增大初始半径削弱粒子束静电扩散效应达到设计要求;通过背景磁场精确预测,可准确控制束流方向精度。可以看出,研究带电粒子束本身的自洽行为以及与外场的作用,对带电粒子束流的产生、传输特性研究及工程化应用都有重要意义。

PTFE-SiO_(2)复合涂层电子发射特性及抑制放电

目的调控空间电子器件有机介质聚四氟乙烯(PTFE)表面的二次电子发射系数(SEY)接近1,以降低表面电荷沉积速率,减少静电放电(ESD)的发生。方法通过磁力搅拌将PTFE分散液和SiO_(2)粉末混合均匀,制备不同浓度配比的PTFE-SiO_(2)混合溶液,将混合溶液旋涂在覆铜板表面,在80℃烘箱中加热4h得到复合涂层。利用扫描电子显微镜(SEM)对涂层表面形貌进行观察,采用局域漏电流法对复合涂层的二次电子发射系数进行测试,通过MATLAB对表面电势进行仿真计算,在SEM中对复合涂层放电特性进行测试。结果从SEM图可以看出,随着SiO_(2)浓度的增大,复合涂层表面SiO_(2)颗粒变得密集。从SEY测试结果可以看出,在SEY>1的能量区间内,复合涂层的SEY随SiO_(2)浓度的增大而逐渐降低,当SiO_(2)质量分数大于15%后,涂层的SEY基本保持不变;在SEY<1的能量区间内,当SiO_(2)浓度为15%时,复合涂层的SEY达到最大值。表面电势仿真计算结果及放电测试结果显示,复合涂层能有效降低表面电荷沉积速率及增大放电阈值。结论当SiO_(2)颗粒质量分数为15%时,复合涂层SEY的调控效果最显著,SEY最大值从2.0变化到1.6,10keV能量下的SEY从0.6变化到0.8。当SiO_(2)颗粒质量分数大于15%时,复合涂层能有效降低真空器件PTFE表面电荷沉积速率,提高放电阈值,减少静电放电的发生。因此,这是一种有效提高航天器电子器件可靠性和工作时间的表面处理方法。

基于干扰观测器的空间惯性传感器自适应控制

针对空间引力波探测航天器内部惯性传感器超高精度控制问题,提出一种基于干扰观测器的自适应控制方案,应用于探测航天器内部双检验质量静电悬浮控制,为探测任务提供高精度惯性基准。基于对系统附加干扰的观测与反馈,来设计干扰观测器实现对系统驱动噪声及非驱动噪声的分别估计;基于反步控制结构设计,基于神经网络的自适应反馈控制器,实现闭环噪声抑制与传感器电压驱动的非线性不确定性逼近。利用Lyapunov方法分析各闭环信号的收敛性,通过数值仿真来验证所提方案相比传统控制方案有更好地的稳定性,在探测频段内,非敏感轴各自由度闭环位移噪声水平达到10^(-15)m/s^(2)/Hz^(1/2)量级,残余加速度噪声水平达到10^(-14)m/s^(2)/Hz^(1/2)量级。相比常规状态反馈控制方案,噪声抑制性能提升约60%。

空间引力波探测惯性传感器关键技术与进展

空间引力波探测任务中的核心科学载荷之一是惯性传感器,旨在探测极其微弱的空间引力波的波纹变化。首先介绍了空间惯性传感器的探测机理和工作原理;然后从电容位移传感、静电反馈控制、地面评价3个方面介绍了惯性传感器设计的关键技术;并且对国内外惯性传感器的发展研究现状进行了梳理,可以看到惯性传感器关键指标为残余加速度噪声,国外在该指标上达到3×10^(-15)m/s^(2)/Hz^(1/2),国内与国外存在着3个量级的差距,因此开展高精度空间惯性传感器研究与设计具有重大战略意义和科学意义,是中国有望赶超世界科技前沿或领跑世界科技研究的重要方向之一。面向中国未来空间引力波探测任务中的惯性传感器需求,可以聚焦于惯性传感器控制体制策略、交流执行机参数优化、多自由度解耦控制技术、低噪声技术这四个方面的研究。

Influence of wire spacing and plate spacing on electrostatic precipitation of nanoparticles: An approach involving electrostatic shielding and diffusion charging

Electrostatic precipitation is a process widely used as gas cleaning device,to removal particles from gas flows.However,in a conventional and well-sized precipitator,the collection efficiency decreases for ultrafine particles,making it difficult to employ this equipment for controlling nanoparticle pollution.This paper investigates the influence of plate spacing(4 and 6.5 cm)and wire spacing(4,6,and 12 cm)on the electric current and nanoparticle collection efficiency,considering the effect of diffusion charging and electrostatic shielding.Two laboratory-scale dry wire-plate electrostatic precipitators with different plate spacings were tested for the collection of nanoparticles(6.15–241.4 nm)at three air velocities(1.9,2.9,and 3.9 cm/s).The results demonstrated the effectiveness of the equipment in removing nanoparticles(99.9%)under the highest electric fields.Higher values of the wire spacing led to increases in the current and the collection efficiency.This was associated with reduced electrostatic shielding,which is more evident in smaller ducts with a higher density of field lines.It is expected that the findings should improve knowledge on electrostatic precipitation of nanoparticles,enabling optimization of collection efficiency by considering the effects of geometric parameters.

空间尘粒静电除尘模块设计与试验验证

针对航天员在轨出舱活动归舱时可能将空间环境中的污染物携带进入空间站内的风险,研究通过等离子体环境对空间尘粒荷电,并对被荷电尘粒进行静电场集尘(electrostatic field precipitation,EFP)。首先分析空间尘粒的静电荷电与静电吸附机理,进行前端尘粒荷电计算;然后引入多依奇(Deutsch)捕集效率模型,以影响EFP模块捕集效率的关键参数——风速、结构参数和激励电压为对象进行仿真研究,确定了EFP模块的参数设计;最后对按照设计参数加工的EFP模块进行试验验证,结果表明该模块的尘粒捕集效率可达85%以上,满足了对空间尘粒亚高效过滤清除的需求,可为空间尘粒清除装置的进一步开发提供参考。

Design space of electrostatic chuck in etching chamber

One of the core semiconductor devices is the electrostatic chuck. It has been widely used in plasma- based and vacuum-based semiconductor processing. The electrostatic chuck plays an important role in adsorbing and cooling/heating wafers, and has technical advantages on non-edge exclusion, high reliability, wafer planarity, particles reduction and so on. This article extracts key design elements from the existing knowledge and techniques of electrostatic chuck by the method proposed by Paul and Beitz, and establishes a design space systematically. The design space is composed of working objects, working principles and working structures. The working objects in- volve electrostatic chuck components and materials, classifications, and relevant properties; the working principles involve clamping force, residual force, and temperature control; the working structures describe how to compose an electrostatic chuck and to fulfill the overall functions. The systematic design space exhibits the main issues during electrostatic chuck design. The design space will facilitate and inspire designers to improve the design quality and shorten the design time in the conceptual design.

Influence of mechanical damage generated by small space debris on electrostatic discharge

Recent studies have indicated that hypervelocity impacts by meteoroids and space debris can induce spacecraft anomalies. However, the basic physical process through which space debris impacts cause anomalies is not entirely clear. Currently, impact-generated plasma is thought to be the primary cause of electrical spacecraft anomalies, while the effects of impact-generated mechanical damage have rarely been researched. This paper presents new evidence showing that impact-generated mechanical damage strongly influences electrostatic discharge. Hypervelocity impact experiments were conducted in a plasma drag particle accelerator, using particles with diameters of 200–500 ?m and velocities of 2–7 km/s. The impact-generated mechanical damage on a specimen surface was measured by a stereoscopic microscope and 3D Profilometer and it indicated that microscopic irregularities around the impact crater could be responsible for local electric field enhancement. Furthermore, the influence of impact-generated mechanical damage on electrostatic discharge was simulated in an inverted potential gradient situation. The experimental results show that the electrostatic discharge voltage threshold was significantly reduced after the specimen was impacted by particles.

果树树冠静电喷雾的空间电荷效应分析

以风送静电喷雾机为例,描述了杀虫剂药液被气流剪切式喷嘴雾化时雾滴的诱导充电过程,建立了一个树冠静电喷雾过程的电子—机械简化模型,用于分析雾滴沉积过程中作用于荷电雾滴的静电力(镜像力、空间电荷力和空间电荷引力)和机械力(重力和拉力)。静电力的相对大小是通过与机械力的力比值作比较的,50μm和100μm两种充电雾滴的典型的力比值说明空间电荷引力在雾滴沉积过程中起着重要的作用。

纳米复合聚乙烯材料中的两相界面及其荷电行为

纳米复合聚烯烃绝缘材料有望在未来应用于高压直流电缆的制造,但纳米粒子改善介质电性能的根本机制尚未完全清楚。一般认为,在纳米复合聚烯烃介质中,纳米粒子与聚合物之间形成的两相界面对材料的宏观性能起到了关键性作用。Lewis和Takada分别基于胶体化学和静电学理论提出了不同的纳米复合介质中的界面模型,Tanaka根据经过表面处理的纳米粒子与聚合物基体之间的可能关系,提出了多核模型。这些模型都强调了界面对电荷的存储作用,认为复合介质通过存储电荷来改善介电性能。该文综合了国内外研究人员对纳米复合聚乙烯介质界面区微观表征的一些成果,研究人员的研究成果表明:静电力显微镜、同步辐射小角X射线散射、Zeta电位测量等方法和技术,可以作为探测纳米复合介质中的界面荷电现象的可行的手段。多种方法研究表明:在未经极化的Si O2、Al2O3复合聚乙烯体系中观测到了界面荷电分布,符合Lewis的界面荷电模型;而未经极化的Mg O复合体系中未探测到界面荷电现象。热刺激电流(TSC)测试表明复合体系的共同之处是形成均匀致密分布的深陷阱,而且材料的空间电荷抑制特性与这些深陷阱的存在密切相关。在纳米粒子与聚乙烯的复合物中,不论是纳米粒子与聚乙烯直接接触荷电,还是通过外场极化形成界面荷电,都可以理解成电荷入陷深陷阱,深陷阱界面荷电区激发的库仑场,是体系抑制空间电荷注入与改善直流电性的可能机制。

新型电聚结器结构参数对液滴聚结特性的影响

设计包覆绝缘层的高压电极并加工4种新型静电聚结器,采用水/原油乳状液为试验介质,利用显微高速摄像系统结合图像处理技术对水滴的聚结规律进行观察和分析,探索电极层数、电极间距和电场强度等因素对水滴聚结特性的影响。结果表明:包覆绝缘层的高压电极可有效防止电击穿现象的发生,增加电场强度,提高电场作用时间有助于油水分离,但高于临界场强后容易导致液滴破碎;电极层数不同时,只要达到一定的电场强度均能促进液滴聚结,但多层电极处理量大,经济效益显著;极板间距较小时,能耗低但电场畸变严重,在满足工作场强的前提下可以适当增加电极间距;能耗受含水率、电极层数和极板间距等条件影响,综合考虑各因素可降低能耗。

基于SIMION软件的空间等离子体探测器的数值仿真

空间等离子体探测器采用带偏转板的柱形静电分析器作为传感器,具有大于320°探测视场,可探测约10eV～30keV的热等离子体。利用SIMION软件采用均匀随机抽样建立粒子源的方法仿真探测器的基本特性参数:静电分析器因子、能量分辨率、偏转板因子和偏转角。仿真结果与实测结果吻合很好。静电分析器因子的仿真与实测结果偏差为3.2%,能量分辨率仿真与实测结果偏差为1.5%,偏转角-偏转板因子的关系式与实测结果的相关系数为0.999 4。仿真结果可以有效地应用于该类仪器的设计和定标过程中。

空间薄膜反射镜的研究发展现状

空间薄膜反射镜由于具有面密度低,易于折叠展开且成本低等优点很好地满足了空间反射镜的超轻量、超大口径的要求,因此在空间科学研究领域倍受关注。介绍了空间薄膜反射镜的发展,包括薄膜反射镜的理论基础,充气式薄膜反射镜和静电拉伸薄膜反射镜及其他类型的反射镜的代表成果。而后对空间薄膜反射镜的技术难点进行了分析;重点讨论了薄膜反射镜用聚酰亚胺薄膜的生产情况以及薄膜反射镜的面形控制、面形检测和反射镜支撑结构的设计。最后总结了反射镜近期的研制情况、存在的问题和应用发展趋势。认为空间薄膜反射镜作为国内外空间科学的热点,在未来的几十年内将在航天领域的太空望远镜、空间侦察相机、人造太阳、微波天线等方面得到广泛应用。