脉冲等离子体推力器宏观特性数值研究

为了揭示脉冲等离子体推力器（Pulsed plasma thruster,PPT）的宏观工作特性,以传统＂弹丸＂模型为基础,提出了一种基于电磁和气动耦合加速机理的计算模型以及延时气化效应的评估方法,并与LES-6,LES-8/9 PPT进行模型验证和实验对比。结果表明,计算所获得的PPT脉冲烧蚀质量等宏观特性与实验数据吻合较好;脉冲烧蚀质量中仅有较少一部分（LES-6约10%,LES-8/9约28%）被离子化和电磁加速排出（约31.6km/s）,其余绝大部分则是在主放电结束后以中性气体混和物低速排出（约460～680m/s）;电磁加速对PPT元冲量的贡献是主要的（LES-6约77%,LES-8/9约86%）;增强电磁加速,尤其是减少延时气化效应对PPT效率的提高是十分必要的。     

脉冲等离子体推力器烧蚀建模与仿真

为了深入地揭示平板型脉冲等离子体推力器（PPT）工作机理,通过对PPT在放电过程中的欧姆加热能量分配分析,建立了基于能量守恒原理的改进烧蚀模型,并对磁流体动力学方程中的能量方程进行了修正。结合LES-6对PPT工作过程进行了一维磁流体动力学数值仿真,获得了PPT的速度分布、放电烧蚀质量和元冲量等参数的变化过程。仿真结果表明,改进模型能正确地反映脉冲等离子体推力器工作过程,仿真得到的出口速度、元冲量与实验值吻合较好,而放电烧蚀质量则相对误差较大;当电容容量变化时,元冲量随放电能量增大呈近似的线性增长关系,放电烧蚀质量随放电能量的增大单调增加且呈非线性关系。     

高压脉冲圆柱形阳极层霍尔等离子体加速器实验

描述了一台大尺寸高压脉冲阳极层霍尔等离子体加速器。对其磁场分布进行了分析,并进行了初步实验,包括放电特征、离子流引出特征、离子束形貌等特性,以验证大尺寸的圆柱形阳极层霍尔等离子体加速器在高功率条件下的运行状况。实验发现此霍尔等离子体加速器工作稳定,可以在较高的功率上运行（大于3kW）,电流利用率较高,可超出90%,工作电压范围很宽,可在300～2kV工作,束流汇聚性良好。     

螺旋波等离子体推进研究进展

螺旋波等离子体推力器是一种新概念磁等离子体推进装置,以其电离率高、无电极烧蚀、寿命长、比冲高等优点受到国内外学者的广泛关注,该新型推力器在未来长寿命深空探测器和卫星的动力系统中具有广阔的应用前景。概述了螺旋波等离子体推力器的系统组成和工作原理、重点介绍了该推力器的研究进展、现状和关键技术,总结了国外在研的四种典型的推力器结构类型,并根据实际情况,提出了国内螺旋波技术在电推进领域的研究方向和发展思路。     

边界形状影响等离子体射流扩展特性的实验研究

为了探索燃烧室边界形状在控制燃烧稳定性方面的特性,设计了圆柱型和圆柱渐扩型充液室,运用高速录像系统研究了等离子体射流在充液室中的扩展过程。结果表明：等离子体射流在液体工质中扩展时,等离子体一液体两相流体速度差较大,TaylorHelmh01tz不稳定效应强烈,圆柱型充液室中,Taylor空腔界面自由,界面增长随机脉动性较大;渐扩型充液室能够使两相流边界受到约束,使Taylor空腔沿着充液室边界逐级扩展,从而减弱了Taylor-Helmholtz不稳定效应,有效抑制了界面增长的随机脉动性。放电电压、喷嘴直径和渐扩结构因子△D／L对Taylor空腔扩展过程均有不同程度的影响,通过对这些参数的优化匹配,可以在一定程度上实现对射流扩展过程的控制。     

Porous Alumina Ceramics Fabricated by Spark Plasma Sintering

Porous alumina of regular spherical particles was fabricated with the spark plasma sintering (SPS) and then compared to those ob-tained through conventional hot pressing (HP). The effects of the parameters of the heating process on porosity were also investigated. Microstructural studies suggest that porous ingots including regular pores be made out of regular spherical alumina particles due to the close sphere packages. A comparative study on the relative necks of the specimens produced by SPS and HP indicates an enhancement of neck growth with SPS. Contrasting the theoretical values to the experimental results over the relative necks indicates that a proper relationship between the relative necks and the porosity can be established by a sintering model.     

Interplanetary Physics Research in China During 2004 - 2005

This brief report summarized the latest advances of the interplanetary physics research in China during the period of 2004-2005, made independently by Chinese space physicists and through international collaboration. The report covers all aspects of the interplanetary physics, including theoretical studies, numerical simulation and data analysis.     

Theory and Simulation of Reconnection

Reconnection is a major commonality of solar and magnetospheric physics. It was conjectured by Giovanelli in 1946 to explain particle acceleration in solar flares near magnetic neutral points. Since than it has been broadly applied in space physics including magnetospheric physics. In a special way this is due to Harry Petschek, who in 1994 published his ground breaking solution for a 2D magnetized plasma flow in regions containing singularities of vanishing magnetic field. Petschek’s reconnection theory was questioned in endless disputes and arguments, but his work stimulated the further investigation of this phenomenon like no other. However, there are questions left open. We consider two of them – “anomalous” resistivity in collisionless space plasma and the nature of reconnection in three dimensions. The CLUSTER and SOHO missions address these two aspects of reconnection in a complementary way -- the resistivity problem in situ in the magnetosphere and the 3D aspect by remote sensing of the Sun. We demonstrate that the search for answers to both questions leads beyond the applicability of analytical theories and that appropriate numerical approaches are necessary to investigate the essentially nonlinear and nonlocal processes involved. Necessary are both micro-physical, kinetic Vlasov-equation based methods of investigation as well as large scale (MHD) simulations to obtain the geometry and topology of the acting fields and flows.     

Detector of Micrometeoroid and Artificial Space Debris Particles

The mathematical model of a space debris detector based on inflatable metal-dielectric-metal (MDM) film structure is presented. The efficiency of its implementation for detection of space debris particles at different altitudes is estimated, and the information obtained by the detector is investigated.     

消融控制电弧等离子体发生器放电特性的实验研究

通过衬套材料消融补充等离子体从而控制电弧生长的技术具有很好的应用前景。利用一个总贮能800kJ的模块化电容基脉冲功率源系统为消融控制电弧等离子体发生器强流放电提供电能输入，在一定的参数变化范围内，实验研究了脉冲功率源初始放电参数、等离子体发生器几何参数以及消融材料对消融控制电弧放电特性的影响规律。借助于理论分析，也可定性获得消融控制电弧等离子体压力和温度对上述影响参量变化的依赖关系。