A new application field of plasma spraying technique to environmental depollution

To expand the application of plasma spraying technique, TiO2 coatings were prepared using agglomerated anatase TiO2 powder to solve the environmental problems. The composition and photocatalytic activity of plasma sprayed TiO2 coatings were investigated systematically. The content of anatase TiO2 in the sprayed coatings was approximate to 7%- 15%, which was influenced by the melting state of TiO2 powder in plasma spraying process. The surface of sprayed coating was very rough and the arithmetical mean deviation of the surface profiles (Ra) was in the range of 5.7 - 8.8 μm. Under lower arc current, the surface of the coating became rougher. The anatase to rutile phase transformation temperature of agglomerated anatase TiO2 powder was approximate to 1 173 K. The TiO2 coating sprayed under the arc current of 400 A had good photocatalytic activity for the relative high content of anatase phase in it. It is concluded that the application of plasma spraying technique to environmental field has been developed.

Physical properties of relativistic electron beam during long-range propagation in space plasma environment

It is known that ion channel can effectively limit the radial expansion of an artificial electron beam during its longrange propagation in the space plasma environment.Most prior studies discussed the focusing characteristics of the beam in the ion channel,but the establishment process and transient properties of the ion channel itself,which also plays a crucial role during the propagation of the relativistic electron beam in the plasma environment,were commonly neglected.In this study,a series of two-dimensional(2D)particle-in-cell simulations is performed and an analytical model of ion channel oscillation is constructed according to the single-particle motion.The results showed that when the beam density is higher than the density of plasma environment,ion channel can be established and always continues to oscillate periodically over the entire propagation.Multiple factors,including the beam electron density,initial beam radius,and the plasma density can affect the oscillation properties of ion channel.Axial velocity of the beam oscillates synchronously with the ion channel and this phenomenon will finally develop into a two-stream instability which can seriously affect the effective transport for relativistic electron beam.Choosing appropriate beam parameters based on various plasma environments may contribute to the improvement of the stability of ion channel.Additionally,radial expansion of the beam can be limited by ion channel and a stable long-range propagation in terrestrial atmosphere may be achieved.

A Mirror-like ECR Plasma Source for Ionosphere Environment Simulator

A compact mirror-like ECR (electron cyclotron resonance) Plasma source for the ionosphere environment simulator was described for the fort time in China. The Overall sources system was composed of a 200 W 2.45 GHz microwave source, a coastal 3A./4 TEM-mode microwave resonance applicator, column and cylindrical Nd-Fe-P magnets, a quartz bell-shaped discharge chamber, a gas inlet system and a plasma-diffusing bore. The preliminary experiment demonstrated that ambi-polar diffusion plasma stream into the simulator (-500 mm long) formed an environment with following parameters: a plasma density ne of 104 cm-3 - 106 cm-3, an electron temperature Te < 5 eV at a pressure P of 10-1 Pa-10-3 Pa, a Plasma uniformity of > 80% over the experimental target with a 160-mm-in-diameter, satisfying primarily the requirement of simulating in a severe ionosphere environment.

Influence of water environment on paint removal and the selection criteria of laser parameters

Laser paint removal in a water environment does not diffuse ablation pollution products into air.Characteristics of water,such as high specific heat and heat flux,generate different effects of the laser paint removal than in an air environment.In this study,the effects of air and water environments on the mechanism and effect of laser paint removal are analyzed and compared experimentally and theoretically.In air,thermodynamic ablation causes removal of paint,whereas in water,stress coupled with plasma shock waves cause tear and splash removal of paint layers after fracture and damage.Fracture and pressure thresholds of the paint and substrate,respectively,indicate the optimum energy density range for laser paint removal in water,providing a reference for engineering applications.

Impurity modes in two-dimensional strongly coupled complex plasma crystals

Complex plasma fluctuation processes have been extensively studied in many aspects,especially lattice waves in strongly coupled plasma crystals,which are of great significance for understanding fundamental physical phenomena.A challenge of experimental investigations in two-dimensional strongly coupled complex plasma crystals is to keep the main body and foreign particles of different masses on the same horizontal plane.To solve the problem,we have proposed a potential well formed by two negatively biased grids to bind the negatively charged particles in a two-dimensional(2D)plane,thus achieving a 2D plasma crystal in the microgravity environment.The study of such phenomena in complex plasma crystals under microgravity environment then becomes possible.In this paper,we focus on the continuum spectrum,including both phonon and optic branches of the impurity mode in a 2D system in microgravity environments.The results show the dispersion relation of the longitudinal and transverse impurity oscillation modes and their properties.Considering the macroscopic visibility of complex mesoscopic particle lattices,theoretical and experimental studies on this kind of complex plasma systems will help us further understand the physical nature of a wide range of condensed matters.

低温等离子体空气消毒机在骨科病室的应用效果

目的 针对医院骨科病室环境的常态化消毒需求,研制基于低温等离子体技术的空气消毒机,探究其在骨科病室患者住院、家属陪同、医护治疗的动态环境中的空气消毒效果。方法 以西安交通大学第二附属医院骨科病室环境为研究对象,采用自制的低温等离子体空气消毒机进行病室空气消毒,利用安德森六级筛孔空气碰撞式微生物采样器对室内空气中微生物浓度进行采样,分析低温等离子体消杀对病室空气中不同种类微生物的影响,揭示该技术对空气中悬浮微生物的消杀机制。结果 利用低温等离子体协同催化剂对病室环境进行间歇式消毒,能够保持室内臭氧浓度低至5 ppbv以内,消毒3 h后病室空气中自然菌的菌落总数减少至约150 CFU/m^(3),消亡率达92.35%;消杀2 h后马赛血杆菌的消亡率达100%;消杀3 h后人葡萄球菌、蜡样芽孢杆菌、霉菌、藤黄微球菌的消亡率分别为90.48%、80.90%、87.50%和92.82%。结论 利用低温等离子体协同催化剂的空气消毒机对病室动态环境进行间歇式消毒,室内臭氧浓度达到了一级国家标准线,在有效控制臭氧产生造成二次污染的同时,可高效杀灭空气中悬浮微生物,病室环境接近《GB 15982-2012医院消毒卫生标准》中Ⅰ类环境标准。等离子体-催化协同消杀具有高效消毒和人机共存的技术优势,可以在保障病室内空气质量安全的同时,减轻护理人员的工作量,是辅助甚至替代现有物理化学手段的有效方法。

A Simulator for Producing of High Flux Atomic Oxygen Beam by Using ECR Plasma Source

In order to study the atomic oxygen corrosion of spacecraft materials in low earth orbit environment, an atomic oxygen simulator was established. In the simulator, a 2.45 GHz microwave source with maximum power of 600 W was launched into the circular cavity to generate ECR (electron cyclotron resonance) plasma. The oxygen ion beam moved onto a negatively biased Mo plate under the condition of symmetry magnetic mirror field confine, then was neutralized and reflected to form oxygen atom beam. The properties of plasma density, electron temperature, plasma space potential and ion incident energy were characterized. The atomic oxygen beam flux was calibrated by measuring the mass loss rate of Kapton during the atomic oxygen exposure. The test results show that the atomic oxygen beam with flux of 1016-1017 atoms-cm-2·s-1 and energy of 5-30 eV and a cross section of φ80 mm could be obtained under the operating pressure of 10-1-10-3 Pa. Such a high flux source can provide accelerated simulation tests of materials and coatings for space applications.

Comparison of electrochemical properties of atmospheric pressure plasma coatings for Al_2O_3-3TiO_2 and CoNiCrAlY in sea water

To improve the durability of underwater rotating products,the corrosion characteristics in harsh marine environment were evaluated through various electrochemical experiments on the Al2O3-3TiO2 and CoNiCrAlY coating layers by atmospheric pressure plasma spray coating process.By evaluating the corrosion resistance of these materials,their applicability to environmentally friendly power generation equipment such as blades of tidal current turbines was examined.According to the Tafel analysis for micro-areas including the coating layer,the coating/metal interlayer and the base metal,the Al2O3-3TiO2 coating layer and the CoNiCrAlY coating layer show markedly lower corrosion current density than the base metal.The corrosion current density of the CoNiCrAlY coating layer (9.75316×10-8A/cm2) is about 1.6 times more than that of the Al2O3-3TiO2 coating layer (6.13139×10-8A/cm2).

无碰撞磁场重联地面实验平台的研制与建设

中国科学技术大学无碰撞磁场重联实验平台(KRX)是以揭示无碰撞磁场重联的触发机制、对无碰撞磁场重联电子扩散区的结构及相关等离子体波动进行深入细致研究为目标而建设的大型等离子体装置,是开展空间环境基本物理过程地面实验模拟的综合性平台.装置主体为直线位形,真空室直径3 m,由多段拼接而成,整体呈胶囊型,内部采用2 m×1 m全球最大氧化物阴极源产生均匀的背景等离子体.装置外部环绕10组导向场磁线圈,内部由上下两块平行电流板通同向脉冲电流构建重联磁场位形,脉冲电源采用“H”桥结构实现了可控的变速率重联驱动.在装置四周共开设200多个真空窗口,能够通过探针阵列及太赫兹偏振干涉仪、激光诱导荧光等先进光学诊断系统对磁场重联过程开展全域、主动、高精度的测量.该平台是最新一代磁场重联实验平台,其重联区域尺寸达到10倍离子惯性长度,伦德奎斯特数S有望达到105,为开展无碰撞磁场重联实验创造了良好条件,能够对磁场重联过程开展多尺度、全面细致的研究,是卫星观测和数值模拟研究重要补充.目前,实验平台已完成基础建设以及诊断等关键组件的研制,并在小型装置预研结果的基础上完善了针对多尺度、多磁岛合并、三维磁场重联等热点问题的研究方案.

月球南极尘埃等离子体环境特性

由于缺少大气和全球性磁场的保护,空间等离子体环境可直接作用于月球表面的月壤层,月壤中较小粒径的月尘带电后会在月面附近形成复杂的尘埃等离子体环境,影响探月任务的顺利实施.针对月球南极尘埃等离子体环境,本文利用SPIS(spacecraft plasma interactions software)软件,仿真研究了月球南极0—200 m高度范围的等离子体和月尘的空间分布情况及月面充电特性,揭示了月面附近尘埃等离子体环境特征及悬浮在月面附近的带电月尘对等离子体环境的影响.仿真结果与Apollo探测数据和Popel团队的理论数据吻合.研究结果:表明空间电位随着高度升高而增加,月球南极附近0—10 m电位约为–40 V,在100 m处空间电位约为–20 V;在10 m以下高度范围内月尘密度为10^(7.22)—10^(4.66) m^(–3);月表附近尘埃等离子体中的电子密度为10^(5.47) m^(–3),离子密度为10^(6.07) m–3,并随着高度升高而增大;带电月尘会影响月尘的空间分布,主要是通过影响空间电场的分布,进而导致电子分布差异,对离子的影响不大.

水环境中锑分析检测方法的研究进展

锑(Sb)是广泛存在于水环境中的一种重金属,不断被证实对人和动植物等有慢性毒性和致癌风险。在监测和治理水环境中的Sb污染方面,建立快速、高灵敏度的Sb检测分析方法至关重要。重点阐述了分光光度法、原子荧光光谱法(AFS)、电感耦合等离子体质谱法(ICP-MS)、电感耦合等离子体原子发射光谱法(ICP-OES)、原子吸收光谱法(AAS)和电化学分析法在Sb分析检测中的相关研究及应用进展,探讨了水环境中Sb检测存在的问题和面临的挑战,如检测方法灵敏度低、间接测定Sb耗时且不准确、还原剂昂贵且有毒等。此外,对Sb检测未来的发展方向进行展望。未来Sb检测趋势是发展电化学分析方法。通过电极修饰和纳米材料设计提高传感器性能,如碳基材料、金属纳米颗粒和硅基材料。有机配体、纳米复合材料和裸电极的功能化可增强灵敏度和选择性,促进传感器小型化。未来Sb检测将迈向小型化、芯片化和快速化。

一种C波段雷达接收机防护技术研究

随着战场环境日益复杂,尤其是高对抗环境下,对现有各类装备均产生了极大威胁。设计了一款C波段雷达接收机保护器,采用充气微波开关管+波导同轴转换的结构设计,创新性地提出将固态限幅器芯片融合在波导同轴转换内部,限幅芯片采用级联的形式,提高了微带限幅器的承受功率。实现接收机保护器耐受功率10 MW以上,响应时间5 ns以内,不仅可用于雷达发射期间接收机防护,还可应对外部电磁干扰、高功率微波攻击。

木星尘埃流动力学仿真过程中的随机充电策略

针对现有尘埃动力学仿真多使用连续充电策略,忽略电荷“量子化”性质对于纳米尺寸尘埃颗粒的影响这一问题,以起源于木卫一的木星尘埃流现象为研究对象,在动力学建模过程中考虑随机充电过程,以更合理地模拟纳米尺寸尘埃颗粒表面电量和轨迹的演化过程。随机充电模型仿真结果表明,只有8~200 nm尺寸范围内的尘埃颗粒可以以6~240 km/s的速度从木星磁层中逃逸。与连续充电模型的仿真结果进行对比,发现对于携带少量电荷的极小尺寸的尘埃颗粒而言,在其动力学模拟过程中考虑充电机制的“量子化”和“随机性”特点是必要的。最后通过简化模型针对尘埃流颗粒的尺寸范围进行了估计,理论结果和随机充电模型仿真结果基本相符。木星系统奇特的等离子体环境和磁场环境共同塑造了尘埃流现象,而随机充电过程则进一步使得尘埃颗粒的轨迹演化变得复杂多样。

重量法-电感耦合等离子体原子发射光谱法联用测定无取向硅钢磷酸盐体系环保涂层液中二氧化硅含量

二氧化硅是无取向硅钢环保涂层液的核心成分,其含量直接影响硅钢涂层的固化工艺及涂层产品的磁性能。因此为保证涂覆过程的顺利进行,对涂层液中二氧化硅含量的检测是十分必要的。通过在样品中分别加入硝酸、过氧化氢及高氯酸,置于电热板上进行消解处理,处理后的样品经酸溶、过滤步骤,以重量法计算沉淀中二氧化硅的含量,采用电感耦合等离子体原子发射光谱(ICP-AES)法测定滤液中可溶性硅含量,则样品中二氧化硅含量为重量法和电感耦合等离子体原子发射光谱法测定结果的合量。从而建立了重量法-电感耦合等离子体原子发射光谱法联用测定无取向硅钢磷酸盐体系环保涂层液中二氧化硅含量的方法。讨论了样品前处理用消解酸及消解温度、滤液中可溶性硅及含量、ICP-AES仪器检测时的元素干扰。结果表明,检测结果的相对标准偏差(RSD,n=12)在0.76%~1.1%,加标回收率在97.0%~104%。方法可广泛应用于各检测部门对无取向硅钢磷酸盐体系环保涂层液中二氧化硅含量的监控。

电感耦合等离子体发射光谱法测定水中7种元素的方法验证

本文通过对《水质32种元素的测定电感耦合等离子体发射光谱法》(HJ 776—2015)进行方法验证,从人、机、料、法、环5方面确定实验室满足方法所要求的人员、仪器设备、试剂和标准物质、设施与环境等条件,并确定了Cu、Zn、Fe、Mn、Al、K、Na工作曲线。结果表明,测定工作曲线相关系数均大于0.999,检出限均小于方法检出限,精密度相对标准偏差为0.2%~1.3%,准确度均在标准证书范围内,相对误差为-2.5%~4.3%,加标回收率为97.3%~100.6%,技术指标均满足方法要求,表明该实验室有能力按照该方法开展水中Cu、Zn、Fe、Mn、Al、K、Na等检测工作。

地面实验室模拟空间等离子体环境的初步测试

空间等离子体和航天器的相互作用对航天器的安全有重要影响，利用空间实验来研究这些作用的代价很大，可以通过在地面实验室中模拟空间等离子体环境来低成本地研究这些相互作用．本研究通过使用ＥＣＲ等离子体源期望在地面实验室来近似模拟空间等离子体环境，通过初步测量，我们得到了一个比较均匀的等离子体环境．

空间环境对卫星光通信系统的影响因素分析

分析了空间环境对卫星光通信系统的主要影响因素,包括高能带电粒子辐射、背景光辐照、等离子体辐射等环境。对不同轨道卫星和光通信终端主要器件造成的影响进行了详细的分析。这些影响因素对卫星光通信系统的故障处理及在轨运行保障具有重要的参考价值,通过控制、抑制空间环境影响因素,可以提高卫星光通信系统的性能及其系统稳定性。

放电等离子体技术在改善居室环境方面的研究

放电等离子体技术在净化居室环境方面具有独特的作用。文中综述了用于净化居室空气的放电等离子体反应器结构和类型 ,放电对除去居室空气中的微粒状物质、乙醛和臭气物质等的影响 ,以及放电等离子体与催化剂合用对净化居室环境的影响等。讨论了放电等离子体技术在净化居室环境方面的进一步研究方向及应用前景。

航天器空间环境模拟器中的等离子体分布规律

低轨道航天器的空间等离子体环境主要为低温、低密度、均匀等离子体,本文详细叙述了低轨道空间等离子体的特点,为了准确校准Langmuir(朗缪尔)探针,对空间模拟装置内等离子体的参数分布进行了详细的实验和数据分析,得到了电子密度、电子温度、空间电位、悬浮电位、德拜长度的分布规律,得出校准装置中心200 mm以内为稳定的等离子体,从而在安装位置上有助于更好地对探针校准。

电推进航天器的特殊环境及其影响

文章介绍了应用离子和霍耳电推进系统在航天器周围产生的等离子体和电磁场等特殊环境,讨论了这些特殊环境对航天器各分系统或部件产生的溅射腐蚀、沉积污染、充放电、等离子体干扰、碰撞动力学扰动等影响效应,探讨了研究电推进与航天器相互作用效应的地面试验技术、空间飞行试验技术和模型分析技术,介绍了离子电推进系统与航天器相容性分析评价的技术要点。