Blue emission from hydrogen-containing a-Si：H／SiO2 multilayers and the investigation of its mechanism

A series of hydrogen-containing a-Si:H/SiO2 multilayers with different a-Si:H sublayer thickness were fabricated by layer-by-layer deposition and in situ plasma oxidation in a plasma-enhanced chemical vapor deposition system (PECVD). Optical induced blue emission from the samples was observed by the naked eye at room temperature, which has never been reported in the luminescence study of Si/SiO2 multilayers up to now. Both the photoluminescence (PL) peak and the absorption edge show a blue shift as the a-Si:H sublayer thickness decreases. The origin of the blue emission and the effect of hydrogen are discussed.     

偏滤器部件W/Cu功能梯度材料的热应力缓和

W/Cu功能梯度材料是一种有希望用作聚变反应堆面向等离子体部件的侯选材料。为避免材料在使用过程中的热应力破坏,根据偏滤器部件服役的热流工况,在结合导热能力分析的情况下运用有限元软件对W/Cu梯度材料进行了优化设计。结果表明,成分分布指数的增大以及金属W厚度的增加均使表面工作温度提高;当成分分布指数为1.0～1.2时W/Cu梯度材料有最佳的热应力缓和效果。在30MW/m2的表面热流负荷下,与非梯度材料相比,经过优化设计的W/Cu功能梯度材料的等效热应力降低了62.3%,表面工作温度下降了50℃;而与单纯金属W相比,W/Cu梯度材料的表面工作温度较之降低445℃。     

非均匀动压引起的瞬时局部重联

非均匀动压冲击和冲击突然停止,可能是引起等离子体边界层的局部瞬时重联的一种新机制.用二维可压缩磁流体力学数值模拟方法研究了这两个过程.根据模拟结果,提出了一种新的瞬时重联模型,称为"横向剪切流驱动重联"模型.对这种重联过程在磁层物理中可能的应用进行了讨论.     

H2/O2/Ar可燃气体激光诱导火花点火的实验研究

对H₂/O₂/Ar可燃气体激光诱导火花点火进行了实验研究. 采用Nd:YAG激光器产生的 532 nm激光聚焦击穿气体点火, 并采用激光高速纹影系统对不同初压、激光点火能量、氩稀释度可燃气体点火的火焰结构进行了流场显示. 结果表明, 气体击穿形成椭球形等离子体, 稀疏波与等离子体作用, 在等离子体迎光侧和背光侧分别形成一对反旋的螺旋环, 导致等离子体和随后的火焰面向内弯缺, 在等离子体左侧激光轴附近形成一个向外凸出的气瓣. 等离子体的高温气体诱导火花核的形成, 受壁面反射弱激波或压缩波的作用, 初始层流火焰减速. 弧形火焰阵面与壁面的作用及其与激波或压缩波、稀疏波等作用, 导致层流火焰向湍流火焰转捩. 对摩尔比为2:1:10、初压为53.33 kPa, 激光诱导火花点火的激光器最小输出能量为 15 mJ. 随预混气初压的升高, 激光点火能量越高, 降低氩稀释度, 会加快火焰阵面传播速度.     

等离子体对壳聚糖整理棉织物效果的影响

研究等离子体预处理技术对棉织物壳聚糖功能整理效果的影响.比较3种不同的整理方法.第1种是用柠檬酸及壳聚糖的混合溶液进行一浴整理;第2种是先用柠檬酸溶液再用壳聚糖溶液进行两浴处理;第3种是使用等离子体预处理织物后再经两浴法整理.使用酸性橙Ⅱ对整理后织物染色并测试K/S值.通过测试织物大肠杆菌和金黄色葡萄球菌的抗菌率考察其抗菌性.结果表明,经等离子体预处理后再经两浴法整理的织物的K/S值以及抗菌率较一浴法或两浴法都有所提高,对大肠杆菌和金黄色葡萄球菌的抗菌率高达100%.     

中频交流脉冲电源的研制

研制了150kHz中频交流脉冲电源,给出了中频交流脉冲电源的设计思路和实现方案.该电源采用全桥逆变拓朴电路、PWM控制方式、输出功率叠加的方案,具有输出变压器原边平均电流和副边峰值电流的过流保护功能.其输出峰值电压0~1200V连续可调,频率1~150kH z可调,脉宽占空比10%~40%可调,输出平均电流0~5A,最大输出功率5kW.利用该电源进行了等离子体化学气相沉积和反应溅射实验,证明该电源各项指标运行正常,工作稳定,具有良好的应用价值.     

Plasma sheet stretching accompanied by field aligned energetic ion fluxes observed by the NUADU instrument aboard TC-2

The NUADU (NeUtral Atom Detector Unit) instrument aboard TC-2 recorded 4л solid angle images of charged particles (E >180 keV) spiraling around the magnetic field lines in the near-Earth plasma sheet (at ~ -7 RE, equatorial dawn-to-night side) during a geomagnetic storm (Dst =-219 nT) on August 24, 2005. Energetic ion beam events characterized by symmetrical, ring-like, solid angle distributions around ambient magnetic field lines were observed during a 34-minute traversal of the plasma sheet by the TC-2 spacecraft. Also, observations during these multiple crossings of the plasma sheet were monitored by the magnetometer experiment (FGM) aboard the same spacecraft. During each crossing, a whistler-mode chorus enhancement was observed in the anisotropic area by the TC-2 low frequency electromagnetic wave detector (LFEW/TC-2) at a frequency just above that of the local lower hybrid wave. A comparison of the ion pitch angle distribution (PAD) map with the ambient magnetic field shows that an enhancement in the field aligned energetic ion flux was accompanied by tailward stretching of the magnetic field lines in the plasma sheet. In contrast, the perpendicular ion-flux enhancement was accompanied by a signature indicating the corresponding shrinkage of the magnetic field lines in the plasma sheet. Since both parallel ion-flux and perpendicular ion-flux enhancements occurred intermittently, the data were interpreted to imply a dynamical, oscillatory process of the magnetic field line (stretching and shrinking) in the near-Earth plasma sheet, which might have acted to help establish an interaction region in this area which would support continuous aurora-substorm triggering during the ongoing magnetic storm. The whistler-mode chorus may have been produced due to ion gyro-resonance during particle pitch angle diffusion after the plasma sheet compression.     

射频PECVD方法生长含氢非晶碳膜的结构及摩擦学性能

利用射频等离子体增强化学气相沉积技术在不锈钢表面制备了含氢非晶碳膜.采用Raman光谱、红外光谱、X射线光电子能谱和原子力显微镜等研究了薄膜的微观结构和表面形貌,在栓盘摩擦磨损试验机上考察了薄膜在不同载荷与滑动速度下的摩擦学性能.结果表明:所制备的含氢非晶碳膜具有典型的类金刚石结构特征,薄膜均匀、致密,表面粗糙度小;薄膜与不锈钢球对磨时显示出良好的抗磨减摩性能;薄膜的抗磨减摩性能同对磨件表面上形成的转移膜以及摩擦过程中薄膜结构的石墨化相关.     

Microstructure and Corrosion Resistance of Cr7C3/γ-Fe Ceramal Composite Coating Fabricated by Plasma Cladding

A new type in situ Cr7C3/γ-Fe ceramal composite coating was fabricated on substrate of hardened and tempered grade C steel by plasma cladding with Fe-Cr-C alloy powders. The ceramal composite coating has a rapidly solidified microstructure consisting of primary Cr7C3/γ- and the Cr7C3/γ-Fe eutectics, and is metallurgically bonded to the degree C steel substrate. The corrosion resistances of the coating in water solutions of 0.5 mol/L H2SO4 and 3.5% NaCl were evaluated utilizing the electrochemical polarization corrosion-test method. Because of the inherent excellent corrosion-resisting properties of the constituting phase and the rapidly solidified homogeneous microstructure, the plasma clad ceramal composite coating exhibits excellent corrosion resistance in the water solutions of 0.5 mol/L H2SO4 and 3.5% NaCl.     

ICP-AES法测定铁精矿中硅、磷、砷含量

本文试验研究了电感耦合等离子体发射光谱分析方法测定铁精矿中的硅、磷、砷含量的仪器工作条件及分析谱线,考查了酸碱加入量及基体对测定结果准确度的影响,加标回收率分别为硅99.1%、磷102%、砷101.5%,RSD值均小于5%。分析方法应用于生产,收到了提高检测数据准确度和指导生产实效性的好效果。