面向深空探测的电磁帆推进技术研究进展

电磁帆是一类利用太阳风驱动的无工质或少工质新型推进技术,在需要推力器长时间工作的深空探测任务中具有非常广阔的应用前景。首先介绍了电磁帆的基本概念和主要分类,其次分别介绍了电帆、纯磁帆和磁等离子体帆三类推进方式的系统组成和工作原理,重点介绍了各自的研究现状,并梳理出了相关关键技术,同时介绍了等离子体磁罩技术。最后对电磁帆推进技术研究进展进行了总结,为国内开展此方面研究提供了研究方向和发展思路。     

Identification of seismic activity sources on the subsatellite track by ionospheric plasma disturbances detected with the Sich-2 onboard probes

Using a cylindrical Langmuir probe and the authors’ proprietary two-channel pressure transducer, ionospheric plasma parameter distributions along the orbit of the Sich-2 satellite (Ukraine, 2011–2012) were measured. This paper is concerned with identifying the space–time location of ionospheric plasma disturbance sources, including the epicenters of actual earthquakes (before or during the satellite flyover) and incipient earthquakes on the subsatellite track, from the measured distributions of the electron density and temperature and the neutral particle temperature along the satellite orbit. To do this, the measured ionospheric plasma parameter distributions are connected to the coordinates on the subsatellite track.It is shown that local disturbances in the electron density and temperature and neutral particle temperature distributions in the satellite orbit in the ionosphere may serve as indicators of seismic activity on the subsatellite track. The epicenters of incipient earthquakes may be set off from other plasma parameter disturbance sources associated with seismic activity using information provided by special monitoring and survey centers that monitor the current seismic situation.     

Plasma transport process in the equatorial/low-latitude ionosphere

The behaviour of the equatorial/low-latitude ionosphere and the transport processes during magnetic disturbed and quiet periods of a high solar activity year, 2014, in the American sector are investigated. Parameters used include vertical drift (Vz), transport term (W), NmF2, hmF2 and scale-height (H). The F2 plasma variations followed the diurnal local solar pattern, being higher at daytime. The sunset maximum and sunrise minimum peaks of hmF2 were directly opposite to the scale height (H) pattern. The plasma distribution was basically controlled by combined actions of the electrodynamic convection/thermospheric composition, which is geomagnetic activity dependent. The annual, semi-annual and winter-anomalies of the F2 parameters were higher at the dip equator in comparison with the low-latitude. The Vz pre-reversal peak magnitude coincided with hmF2 peak and the effects are more pronounced during geomagnetic disturbed conditions. The transport term pattern was similar to that of the scale height and it is suggested as a proxy parameter for quantifying low-latitude plasma irregularities and distribution of thermospheric composition.     

Case study of inclined sporadic E layers in the Earth’s ionosphere observed by CHAMP/GPS radio occultations: Coupling between the tilted plasma layers and internal waves

We have used the radio occultation (RO) satellite data CHAMP/GPS (Challenging Minisatellite Payload/Global Positioning System) for studying the ionosphere of the Earth. A method for deriving the parameters of ionospheric structures is based upon an analysis of the RO signal variations in the phase path and intensity. This method allows one to estimate the spatial displacement of a plasma layer with respect to the ray perigee, and to determine the layer inclination and height correction values. In this paper, we focus on the case study of inclined sporadic E (E_s) layers in the high-latitude ionosphere based on available CHAMP RO data. Assuming that the internal gravity waves (IGWs) with the phase-fronts parallel to the ionization layer surfaces are responsible for the tilt angles of sporadic plasma layers, we have developed a new technique for determining the parameters of IGWs linked with the inclined E_s structures. A small-scale internal wave may be modulating initially horizontal E_s layer in height and causing a direction of the plasma density gradient to be rotated and aligned with that of the wave propagation vector k. The results of determination of the intrinsic wave frequency and period, vertical and horizontal wavelengths, intrinsic vertical and horizontal phase speeds, and other characteristics of IGWs under study are presented and discussed.     

等离子体处理对非晶态合金镀层表面改性研究

通过微波等离子体处理方法对Ni-W、Ni-W-B非晶态合金镀层表面进行改性的研究,测量了表面改性对非晶态镀层耐蚀性、表面成分及结构的影响.结果表明,经过微波等离子体处理过的Ni-W、Ni-W-B非晶态合金镀层,提高了在H₂SO₄、HNO₃溶液中的耐蚀性以及在700℃环境下的抗氧化性能;微波等离子体处理过的非晶态合金镀层表面含W量和含O量相对提高了;镀层结构仍然是非晶态.     

低能耗非热等离子体NO还原特性

分别建立了新型低能耗N2-NO系统的单电极尖端放电和介质阻挡放电非热等离子体NO还原实验系统,通过实验研究了电极极问电压V和尖端距离lg以及Al2O3,CaO,MgO,玻璃等不同介质阻挡对活性N原子产生及NO还原率的影响规律。结果表明,NO还原率随尖端距离lg的增大而先增后减,随极间电压Vm和气体停留时间t的增大而增大,尖端距离lg是决定电极之间的电场强度Eg和气流停留时间t的关键几何变量。利用活性N原子的产生条件解释了放电外轮廓直径及电场强度随尖端距离lg变化的消长规律。不同阻挡介质所形成的气体放电的电场强度不同,提供给活性粒子的能量也不同,从而对NO还原效果具有不同的影响。单电极尖端放电NO还原特性的研究结果对介质阻挡放电NO还原有指导作用。     

Kink mode m = 1 in magnetic tube with discontinuous magnetic field

In this paper, we study conditions of realization and stability of kink modes with azimuthal wave numbers $m=\pm 1$ in cylindrical plasma flex with twisted magnetic field and homogeneous current along its axis. We assume permanent axial magnetic field both inside and outside the flex, surrounded by currentless plasma. Azimuthal magnetic field decreases inversely proportional to the distance from the boundary beyond the flex. We derived dispersion equations for stable and unstable modes in approximation of “thin” plasma flex. The analysis of equations has been provided for the case of discontinuous axial magnetic field on flex’s boundary. Conditions of propagation of wave modes have been defined. It was shown, that unstable modes can be implemented in certain interval of longitudinal wavenumbers. Results can be applied for the interpretation of solar magnetic tubes behavior, using measurements, provided by spacecrafts.     

日球层内外能量中性原子的探测

能量中性原子(Energetic Neutral Atoms, ENA, 简称能原子)是指在日球层内外空间, 拥有>0.1keV动能的原子.在此空间领域并没有温度>106K的中性气体, 但却充满动能>0.1keV的正离子.因此能原子A应该是A+离子与原地稀薄气体B原子或分子交换电荷所产生的, 即A++B→A+B+. 电荷交换涉及极小的动能变化, 新生的能原子A和离子B+基本上各自保持原有动能. 离子B+随即被当地磁场俘获, 能原子A则脱离磁场约束并携带其原属离子群的成分和能量信息而直线运动, 成为遥测空间等离子体的有效媒介. 美国人造卫星 IBEX (Interstellar Boundary Explorer) 直接探测得到来自日球层以外星际空间的能原子, 大幅延伸了利用能原子遥测空间等离子体的领域. 本文据此论述了空间能原子的发现, 综述了探测空间能原子的基本概念与实例、取得的主要成果、仪器设计和研制进展以及未来空间利用能原子遥测的发展趋势.      

等离子体鞘套对飞行器再入过程信号传播特性的影响分析

再入飞行器表面所形成的等离子体鞘套会对通信信号的传播产生影响,甚至形成通信黑障。文章从电磁波在等离子体中的传播理论出发,分析建立鞘套对电磁波吸收和反射的数学模型;并以数学模型为基础,编制面向对象的计算软件,考察影响通信信号传播特性的各种因素。结果表明,等离子体鞘套内的电子密度及其分布对通信信号的传播特性有重要影响,减小等离子体密度可显著降低信号的衰减。     

Spectroscopic data and Stark broadening of Cu I and Ag I spectral lines: Selection and analysis

Optical emission and linear laser absorption spectroscopy techniques were used in investigation of plasma with copper and silver admixture. The method of selection of spectral lines and spectroscopic data with the aim of diagnostics of multicomponent air plasma with two metal vapors admixture was developed. Energy level populations behavior on the Boltzmann plot were used for Cu I and Ag I spectroscopic data selection. In this way the selection of spectroscopic data for some of Cu I and Ag I lines was realized. Stark broadening parameters of Cu I and Ag I were examined. Experimentally obtained temperature and electron density radial distributions were used in the calculation of plasma composition in the assumption of local thermodynamic equilibrium. Linear laser absorption spectroscopy was used to examine the state of plasma.