Effect of moderate geomagnetic storms on equatorial plasma bubbles over eastern Africa in the year 2012: Evolution and electrodynamics

Equatorial plasma bubbles (EPBs) are common features of the equatorial and low-latitude ionosphere and are known to cause radio wave scintillation which leads to the degradation of communication and navigation systems. Although these structures have been studied for decades, a full understanding of their evolution and dynamics remains important for space weather mitigation purposes. In this study, we present cases of EPBs occurrences around April and July 2012 geomagnetic storm periods over the African equatorial sector. The EPBs were observed from the Communications/Navigation Outage Forecasting System (C/NOFS) and generally correlated well to the ionospheric irregularities observed from the Global Positioning System total electron content (GPS-TEC) measurements (rate of TEC change, ROT). This study revealed that the evolution of the EPBs during moderate storms is controlled by the strength of the daytime equatorial electrojet (EEJ) currents regardless of the strength of the equatorial ionization anomaly (EIA), the latter is observed during the July storm case in particular. These effects were more evident during the main and part of the early recovery phases of the geomagnetic storm days considered. However, the evening hours TEC gradients between regions of the magnetic equator and ionization crests also played roles in the existence of ionospheric irregularities.     

多种工质下螺旋波等离子体源波场结构数值模拟

针对螺旋波等离子体放电机理，开展了多种工质条件下的螺旋波放电等离子体内波场结构数值模拟研究。计算发现:氦气等离子体的Er分量在径向边界处的峰值更为突出，有利于等离子体在径向的输运，波电场径向分量决定了电流密度径向分量在内部的表现。在0.266 Pa和1.064 Pa两种气体压强条件下，通过波场结构验证了气压对于波阻尼影响的结论。波场结构是螺旋波在等离子体内传播以及能量沉积的微观体现，研究螺旋波波场结构是揭示其高电离效率的重要途径。初步探索了功率耦合机制，为实验系统优化及实验方案设定奠定理论基础。     

RPC-MAG The Fluxgate Magnetometer in the ROSETTA Plasma Consortium

The fluxgate magnetometer experiment onboard the ROSETTA spacecraft aims to measure the magnetic field in the interaction region of the solar wind plasma with comet 67P/Churyumov-Gerasimenko. It consists of a system of two ultra light (about 28 g each ) triaxial fluxgate magnetometer sensors, mounted on the 1.5 m long spacecraft boom. The measurement range of each sensor is ±16384 nT with quantization steps of 31 pT. The magnetometer sensors are operated with a time resolution of up to 0.05 s, corresponding to a bandwidth of 0–10 Hz. This performance of the RPC-MAG sensors allows detailed analyses of magnetic field variations in the cometary environment. RPC-MAG furthermore is designed to study possible remnant magnetic fields of the nucleus, measurements which will be done in close cooperation with the ROSETTA lander magnetometer experiment ROMAP.     

圆柱形Hall推力器磁场的设计与数值模拟

霍尔(Hall)推力器的磁场设计是提高其性能的关键技术之一。针对传统环形Hall推力器小型化带来的缺点,提出了圆柱形的Hall推力器。简要对比了环形和圆柱形两种推力器,对圆柱形推力器的工作原理、磁场设计的要求以及利用ANSYS有限元软件进行的电磁场数值模拟的结果进行了详细分析。结果表明,圆柱形推力器磁路设计是合理的,另外也证明了用ANSYS有限元软件进行电磁场模拟的可靠性。     

空气压强对激光推进器冲量耦合系数影响

设计并加工了激光推进器实验模型,以空气为推进工质,利用脉冲式CO2激光器,研究了空气压强对激光推进器冲量耦合系数影响。实验结果表明,空气压强对激光推进器性能有显著影响。在文中实验条件下,当空气压强大于6 kPa时,激光推进器冲量耦合系数随压强减小而减少较慢;当空气压强小于6 kPa时,激光推进器冲量耦合系数随压强减小而减少很快。     

距离拖引干扰对几种脉冲雷达的干扰效果分析

借助于雷达信号的模糊函数，分析了距离拖引干扰对非脉压雷达、线性调频脉压雷达和二相编码脉压雷达的干扰效果，且进行了比较，得到了一些有用的结果。     

铣槽结构液体火箭发动机推力室壳体热应力分析

介绍了液体火箭发动机推力室铣槽结构热应力的数值分析方法,通过建立液体火箭发动机推力室的流场燃烧和导热理论模型,运用有限体积法考虑液膜冷却计算出发动机工作时的燃气、燃烧室壳体和冷却工质的温度场,将得出的结果作为壳体热应力计算模型的边界条件进行热应力场有限元分析。内、外壁温度的计算数据与实验结果基本相符。     

国外几种新型微化学推力器

介绍了国外几种以微机电系统 (MEMS)技术为基础的液体和固体微化学推力器。这些新型微化学推力器具有MEMS技术微型化、低成本和批量生产的优点 ,并考虑了体积限制和高度集成等空间限制 ,能产生 10 -6～ 10N·s的推力脉冲 ,可用于微型卫星和纳米卫星的姿态调整、变轨和定向的精确控制。同时阐述了这几种微推力器结构特点和制造工艺 ,并与其他类型的推进器进行了比较     

氙离子推力器束流分布特性研究

建立了离子推力器束流分布的高斯模型,以200mm氙离子推力器为例,在不同工作环境下对推力器束流分布进行了数值模拟,并通过试验测量了推力器引出切面不同位置(轴向z=50mm,z=100mm)下的径向束电流密度和束离子密度分布。通过对数值模拟结果与试验测量结果的比较,误差为17%,认为数值模拟结果与试验测量结果吻合较好。表明离子推力器引出束流呈轴对称分布,在推力器出口附近,束离子密度很大,越往下游,密度越小且束流出现发散。     

0.1 kW微波等离子体推力器的试验与数值研究

主要对0.1 kW微波等离子体推力器进行了地面试验和数值模拟研究。试验研究分析了影响推力器效率的因素;数值研究通过采用SIMPLE方法求解了N-S方程和采用FDTD方法求解了M axwell方程,分析了影响谐振腔内等离子体参数的因素。结果表明,微波功率、工质种类和质量流率是影响谐振腔效率的主要因素,而等离子体参数则主要受微波功率的影响。