柱形等离子体辐射场的数值计算和分析

参照金属辐射场的求解方法,在简化条件下计算出柱形等离子体行波传输和驻波传输的辐射图．当改变等离子体密度以及相关参数时,对应的辐射图会相应地发生变化,得出与信号在金属介质中传输相类似的结果．根据理想柱形等离子体表面波的色散关系得到波矢,求出的柱形等离子体辐射方向图与金属介质的辐射方向图相比,会发生较大的变化,因此利用等离子体进行信号传输有一定的价值．     

等离子体对燃气在补燃室中燃烧特性的影响

为研究等离子体对多组分燃气在发动机补燃室中的助燃特性,建立了多组分燃气供给系统以及扩散燃烧实验模型。测量了等离子体炬的发射光谱,得到了等离子体炬的主要激发态粒子;拍摄了多组分燃气在补燃室的扩散火焰照片,得到了等离子体对多组分燃气的扩散火焰形貌的影响;测量了补燃室4个不同截面上的静压和总压,分析了等离子体对多组分燃气在发动机中燃烧效率的影响。实验结果表明:等离子体炬主要产生氮气和氧气的激发态粒子;加入等离子体后,喷出冲压尾喷管的火焰长度得到进一步缩短,说明等离子体可以在更短的燃烧室长度内使得多组分燃气得到更加充分的燃烧;加入等离子体时,补燃室不同截面的静压和总压都会出现突升台阶,说明等离子体可以加快燃气的化学反应速率,提高多组分燃气在发动机中的燃烧效率,且等离子体功率越高,燃气燃烧效率的增长率越高。     

彗星环境中尘埃等离子体的电荷涨落和静电波动

本文分析了尘埃等离子体中尘埃颗粒的带电过程，给出了一套自洽的工流体方程组．运用这组方程研究了尘埃电荷的起伏涨落，得到了非磁化均匀尘埃等离子体中静电波动的色散关系．针对彗星空间环境中尘埃等离子体的特点，讨论了尘埃电荷的涨落对各种静电波动的影响．     

磁尾的平衡结构

考虑到等离子体片和等离子体幔的存在,我们从Vlasov方程出发得出一个自洽的二维磁尾平衡模式。在这个模式中,假设等离子体处于平衡状态,压强是各向同性的,还假设沿磁尾方向各种参数的变化率较垂直于等离子体片方向的变化率要小得多。晨昏方向的变化则完全忽略不计。这个模式体现出磁尾的一些主要结构要素:(ⅰ)高温等离子体组成的等离子片;(ⅱ)等离子体片中的闭合磁力线;(ⅲ)等离子体极其稀薄的磁尾瓣;(ⅳ)等离子体幔;(ⅴ)磁层顶;(ⅵ)张开的磁尾。讨论了等离子体幔的存在对磁尾平衡结构的影响,结论是等离子体幔的存在使磁尾的形状更趋于尾形,于是,至少部分克服了Birn模式的困难。      

空间尘埃等离子体中尘粒电荷的相关涨落对尘埃磁声波的影响

本文运用自洽的三流体方程组, 考虑了尘埃的充电过程, 得到均匀磁化尘埃等离子体中垂直于磁场传播的尘埃磁声波的色散关系, 结合空间环境讨论了尘埃电荷的相关涨落对尘埃磁声波的影响.      

Plasma effects of active ion beam injections in the ionosphere at rocket altitudes

Data from ARCS rocket ion beam injection experiments will be primarily discussed in this paper. There are three results from this series of active experiments that are of particular interest in space plasma physics. These are the transverse acceleration of ambient ions in the large beam volume, the scattering of beam ions near the release payload, and the possible acceleration of electrons very close to the plasma generator which produce intense high frequency waves. The ability of 100 ma ion beam injections into the upper E and F regions of the ionosphere to produce these phenomena appear to be related solely to the process by which the plasma release payload and the ion beam are neutralized. Since the electrons in the plasma release do not convect with the plasma ions, the neutralization of both the payload and beam must be accomplished by large field-aligned currents (milliamperes/square meter) which are very unstable to wave growth of various modes. Future work will concentrate on the wave production and wave-particle interactions that produce the plasma/energetic particle effects discussed in this paper and which have direct application to natural phenomena in the upper ionosphere and magnetosphere.     

空间尘埃的充电过程及与等离子体参数的关系

考虑了地球附近的彗星、行星环、行星际介质等空间尘埃等离子体环境中尘埃颗粒的充电问题．应用典型的空间尘埃等离子体参数，计算了不同种类的尘埃颗粒，以及不同等离子体成分下等离子体中尘粒的平衡电势，得到了尘埃颗粒的平衡电势与尘埃等离子体成分、温度，及其他等离子体参数之间的相互关系．     

均匀磁化暖电子等离子体中的射线方向

本文给出了暖电子等离子体中各种频率波的射线方向.揭示了射线方向矢量的一些重要特征.特别是当波在暖等离子体相应的冷等离子体谐振区附近,暖等离子体中有一个等离子体波在传播.电子等离子体波可以与寻常波或非常波相联接,并使波能比在一个相应冷等离子体中有更宽的传播角域.      

Symmetric model of spacecraft charging and plasma emission effects

The electrostatic charging of satellites in space and the interactions with the plasma in the near surroundings are investigated by making use of symmetric models. In this case, the Vlasov-Poisson system describing the ambient plasma disturbances and the plasma emitted from the surface can be integrated self-consistently within a numerical iteration scheme, and the current balance yields the floating potential of the probe. The spacecraft charging and the potentials in its surroundings are investigated for the following plasma and emission conditions: (1) in the ionosphere in the case of very negative surface potentials, (2) in the solar wind with regard to the HELIOS mission and (3) in the near vicinity of the comet Halley, where a very strong plasma emission due to the impact of neutral gases onto the surface must be regarded. Finally, the importance of the shielding due to the ambient plasma is discussed.     

束流等离子体系统的离子声孤波

考虑热束流等离子体无碰撞地通过背景等离子体时, 由等离子体系统的流体方程组出发用递减扰动法推导了描写离子声孤波的Kortewegde-Vries方程.在弱束流的条件下, 四种离子声波模式中有两种分别对应慢孤波和快孤波.计算了两种孤波振幅对等离子体参量的依赖关系, 在某些参量配合下有可能得到大振幅的正孤波和负孤波.      

利用静电双探针对辉光放电等离子体诊断分析

阐述了利用Langmuir双探针诊断等离子体参数的基本原理,对圆柱腔中的空气辉光放电等离子体进行了双探针诊断,通过实验测得伏安特性曲线,计算得出等离子体密度和电子温度。分析了密度参数变化与放电电流大小之间的关系。最后将诊断结果与准光腔系统进行比较,二者虽略有差别,但差别不大,且变化趋势一致。验证了采用本双探针系统诊断辉光放电等离子体密度的可靠性。     

Structure of plasma blobs injected into the ionosphere from a rocket

To study artificial disturbances in the ionosphere, caused by pulsed injection of plasma two MR-12 rockets with plasma guns were launched from Volgograd in 1978–1979. The pulsed plasma was ejected from the separated daughter payload, alternatively, along and transverse the magnetic field lines. The experimental and model data on structure and dynamics of the artificial plasma blobs in the ionosphere are discussed.     

Characteristics of the equatorial F-region vertical plasma drift observed during post-sunset and pre-sunrise hours

Post-sunset and pre-sunrise vertical plasma drifts at the equatorial F-region have been investigated using the HF Doppler radar and ionosonde observations. Observed vertical plasma drift features during the sunrise are found to complement that observed during the evening. The post-sunset vertical plasma drift is characterized by an upward enhancement, a pre-reversal enhancement and a reversal in the drift direction. Similarly, the pre-sunrise plasma drift is characterized by a sudden downward excursion followed by an upward turning. The wavelet analysis of the plasma drift shows the presence of fluctuations in the period range 4–32 min and the short period fluctuations are attributed to the atmospheric gravity waves.     

Characteristics of equatorial nighttime spread F – An analysis on season-longitude,solar activity and triggering causes

To understand global variability and triggering mechanisms of ionospheric nighttime equatorial spread F (ESF), we analyzed measurements from satellite and a ground-based GPS station for the years between 2010 and 2017. In this study we present seasonal-longitudinal as well as monthly variability of ESF occurrence for solar minimum and yearly variations of ESF occurrence for solar maximum and minimum periods. One of the long standing open questions in the study of ESF is what exactly initiates the Rayleigh-Taylor (RT) plasma instability growth. This question is the focus of the present work. Zonal background eastward electric field and E × B upward plasma drift speed patterns are found to be critically important in understanding plasma irregularity formation. In addition to particular patterns observed on these parameters, the background plasma density in the local evening hours just before the onset of ESF occurrence is very important. Stronger plasma densities just before the onset of irregularities resulted in stronger plasma irregularities, while relatively less dense plasma just before the onset of irregularities resulted in relatively lower plasma irregularities. Seasonal variations in ESF activity between March and September equinox seasons with comparable plasma densities can be defined in terms of the rate of change of solar flux F10.7 (dF10.7/day) index. Strongest ESF occurrence and strongest dF10.7/day are measured in the same month out of all other months in 2016 and 2017. Longitudinal variations of ESF activity in our measurements are related to longitudinal variations of plasma densities. We also found that ESF occurrence is better correlated with rate of change of F10.7 index for months in equinox seasons than for months in solstice seasons for the years between 2013 and 2016.     

Current sheet with medium scale developed turbulence and the formation of the plasma sheet of Earth''s magnetosphere and solar prominences

A current sheet model with developed medium scale turbulence has been constructed. It is suggested that regular plasma flow in the current sheet is compensated by diffusive flux and plasma mixing, leading to temperature equalization. The analyzed turbulence has the form of electrostatic vortices in which electrons and ions move with the same velocities and hence does not lead to anomalous resistivity and current dissipation. It is possible to determine the plasma pressure dependence on magnetic vector potential and to find the Grad—Shafranov equation solutions. The theory is used to explain the Earth's magnetosphere plasma sheet characteristics. It is taken into account that experimentally observed plasma velocity fluctuations in the Earth's plasma sheet and quiescent prominences are much higher than regular plasma flow velocities. The analysis of turbulent current sheet dynamics after the regular motion weakening allows to construct the prominence formation theory. The decreasing of plasma pressure in the sheet due to diffusion leads to field-aligned plasma flow and plasma tube filling by cold chromospheric plasma by the action of siphon mechanism.     

磁层亚暴恢复期间等离子片边界层区的Kelvin—Helmholtz不稳定性

本文根据两个理想的磁流体力学模型研究了磁层亚暴恢复期间等离子体片边界层区的Kelvin-Helmholtz不稳定性。一个模型由三个均匀的等离子体区组成--北尾瓣、等离子体片和南尾瓣。在此模型里,不稳定模式在北(或南)尾瓣和等离子体片之间的边界面上激发。另一个模型由五个均匀的等离子体区组成--北尾瓣、等离子体片北边界层、等离子体片中间层、等离子体片南边界层和南尾瓣,在等离子体片边界层区存在着两种不稳定模式,一种在等离子体片的北(或南)边界层和中间层之间的边界表面上激发(模式Ⅰ);另一种在等离子体片北(或南)边界层和北(或南)尾瓣之间的边界面上激发(模式Ⅱ).模式Ⅰ多数时间是不稳定的。这些不稳定模式可能引起卫星观测到的等离子体边界层的一些特征。      

自身场磁等离子体推力器数值仿真流场特性分析

磁等离子体推力器以其推力大、比冲高等特点,成为未来深空探测、星际航行任务首选的电推力器类型,研究推力器内部等离子体流场特性,有利于解释推力器出现的物理现象。针对特定自身场磁等离子体推力器,建立磁流体模型,使用TVD Lax-Friedrich格式以及ADI方法对推力器内部及羽流进行数值求解,得到等离子体流场及等离子体参数分布情况,仿真结果显示在高电流工况下,等离子体羽流更加集中,轴向加速效果更加显著,但高电流模式下阴极温度较高,不利于阴极的使用寿命。     

Estimation of plasma density from wave data of cold electron plasma

Based on the dispersion relation of electron plasma, one can expect, that the waves excited in the frequency band (f_p, f_u=sqrt(f_p^*f_p+f_c^*f_c)) should persist in experimental spectra. For wave data from a spacecraft immersed in a cold plasma such an assumption may be misleading. In measurements performed on board the INTERCOSMOS-19, ACTIVE, APEX satellites and VC36.064CE rocket the most prominent spectral structure is centered around frequency f_r fulfilling the relation f_crp and corresponds to resonant detection of Bernstein waves excited in the surrounding plasma by spacecraft systems. Input network mismatch at frequencies around fu significantly depresses natural plasma noise as well as that excited by the spacecraft. Plasma emissions in the band (f_p, f_u) are prominent if the electromagnetic excitation is preferential (topside sounders) or if the excitation introduces nonequilibrium components into the plasma e.g. particle beams or clouds. Experimental examples are presented and parameters of cold plasma spectra useful for electron density estimation are discussed. The application to other spacecraft-cold plasma configurations is suggested.     

Inconsistency of magnetic field and plasma velocity variations in the distant plasma sheet: Violation of the “frozen-in” criterion?

Measurements of the magnetic field and low energy plasma by the GEOTAIL spacecraft have been used to study the relationship between variations of the plasma velocity and of the magnetic field in the distant (100–200 R_E) and middle (40–80 R_E) tail. The analysis was carried out separately for the tail lobes and the plasma sheet. It is shown that the absolute values of the magnetic field and plasma velocity, as well as their corresponding components (V_X and B_X, V_Y and B_Y, V_Z and B_Z), are linearly connected in the tail lobes. In the plasma sheet, however, the plasma velocity and the magnetic field do not seem to be related to one another. The distant plasma sheet seems to be in a regime of turbulence. The diffusion coefficients estimated from our data set of the velocity parameters in the plasma sheet are in good agreement with the theoretical predictions of Antonova and Ovchinnikov (1996, 1999).