Numerical analysis of deflection control of a gas plasma jet based on magnetohydrodynamic staggered electrode configuration

To control the deflection of the gas plasma jet, a new analytical method is proposed based on the Magnetohydrodynamic(MHD) technique. Based on the typical MHD power generation model, the applied voltage is applied to the staggered electrodes, that is, a pair of electrodes on the same side wall are connected to generate an axial current in the channel. Under the action of the magnetic field perpendicular to the direction of the flow, the plasma is subjected to electromagnetic forces perpendicular...     

地面实验室模拟空间等离子体环境的初步测试

地面模拟电离层等离子体与高压太阳电池阵的相互作用时,需要一定密度和能量的等离子体环境,因而希望能在地面试验室中利用微波ERC等离子体源来近似模拟空间等离子体环境.文章对该等离子体源进行了初步测试,利用等离子体诊断系统获得了在大真空容器中的等离子体有关参数的测量数据,通过分析,我们得到了一个比较均匀的等离子体环境.     

A Satellite-borne Miniature Ion Mass Spectrometer for Space Plasma

The miniature design technology is an important trend in space exploration. Mass spectrometer is used extensively in the space environment detection. The miniature ion mass spectrometer utilizes a 127° cylindrical electrostatic analyzer accompanied with a Time of Flight (TOF) unit based on ultrathin carbon foil to measure the energy spectra and composition of space plasma. The Time of Flight technique has been used broadly in space plasma measurement. A new type of miniature method for the ion mass spectrometer is introduced. The total mass of the instrument is 1.8 kg and the total power consumption is 2.0W. The calibration results show that the energy measurement range is 8.71～43550eV, the energy resolution is 1.86% and the ion mass from 1 amu (1 amu = 1.67 × 10^-27 kg) to 58 amu can be resolved by the miniature mass spectrometer. The miniature ion mass spectrometer also has a potential to be increased in the field of view by an electrostatic deflecting system to extend its application in space plasma detection. The miniature ion mass spectrometer has been selected for pre-study of Chinese Strategic Priority Research Program on Space Science.     

利用栅网控制空间等离子体环境效应模拟中的等离子体参数

通常采用ECR等离子体源产生的等离子体的温度和密度都比较大,通过附加适当目数的栅网,并在栅网上加一定的偏置电位来对等离子体参数,尤其是温度、密度进行调整,满足空间等离子体环境模拟要求.本文利用14目、25目的栅网,对己有的地面实验室空间等离子体环境进行了改进,得到了更加接近空间等离子体参数的一个地面模拟环境.     

用于SiC超光滑表面加工的大气等离子体抛光系统设计

设计了一套基于射频电容耦合放电原理的大气等离子体抛光原型装置,电容耦合等离子体炬首次被应用到了抛光系统中。针对SiC反射镜的加工实验结果表明,系统工作正常,并可以实现亚纳米级的表面粗糙度。     

天线窗材料热透波特性风洞测试方法

高超声速飞行器天线窗材料在等离子体包覆条件下的热响应和热透波特性测试,是分析天线窗材料特性、研究电磁波在等离子体和天线窗中传输特性的基础。针对等离子体和天线窗中电磁波传输特性,采用矢量网络分析仪和标准增益天线组成的电磁波传输测试系统,获得了一定频率的电磁波经过等离子体和高温天线窗之后的衰减;针对高温天线窗自身热响应特性和电磁波在其中的传输特性,研究了天线窗材料在一定热流作用下的温度分布和烧蚀特性,测试了烧蚀后处于高温状态且无等离子体覆盖的天线窗对电磁波的影响,分析了天线窗高温透波特性与常温透波特性的差异。所建立的方法,为在地面等离子体风洞中开展天线窗热透波特性研究、分析天线窗和等离子体耦合作用对电磁波传输特性的影响建立了基础。     

中心等离子体片的地向对流型高速流

在GSM坐标系下, 利用TC-1卫星和Cluster/C1卫星上4s分辨率的磁场和热离子探测数据, 对中心等离子体片内的地向对流型高速流进行了统计研究(-19 Re < x< -9 Re, |y| < 10 Re, |z|< 5 Re). 统计结果表明, 地向对流型高速流会在15 Re以内出现``刹车', 在11.5 Re附近时出现``缺失'. 进一步对其速度特征进行统计分析. 结果显示, 在中心等离子体片内的高速流, 其运动方向主要为地向, 晨昏和南北方向的运动明显较弱; 在对流型高速流的地向输运过程中, 其峰值速度没有明显的下降; 在近地13 Re以内, 等离子体片内的地向对流型高速流具有较强的垂直磁力线运动速度. 这意味着对流型高速流在近地15 Re以内的“刹车”不是由高速流晨昏或南北方向的偏转造成的. 高速流在11.5 Re附近时出现的``缺失'可能与在15 Re以内出现``刹车'密切相关. TC-1卫星和Cluster卫星的观测为了解中磁尾重联高速流地向输运过程及亚暴膨胀相触发提供了重要的观测依据.     

高超飞行器表面热效应地面模拟实验研究

文章深入分析高超飞行器与临近空间大气相互作用的基本物理过程,激波加热及粒子碰撞产生等离子体的物理机制,并利用磁热屏蔽效应在高超飞行器模拟器与高速定向流间建立磁化等离子体鞘层,大幅降低中性激波气体向飞行器的能流传递,从而为高超飞行器提供有效的热防护作用。通过两次比对实验验证了磁热屏蔽效应的有效性及工程实施的可行性,为今后研制高韧性、超轻质、可重复使用热防护复合材料提供了实验数据,奠定了技术基础。实验中利用层流等离子体源作为高能流密度热源是热防护实验装备上的创新,层流等离子体源能流截面大、能流密度高,可以针对高超飞行器表面热效应进行全尺寸的模拟实验。     

Modeling Multifractality of the Solar Wind

The question of multifractality is of great importance because it allows us to investigate interplanetary hydromagnetic turbulence. The multifractal spectrum has been investigated with Voyager (magnetic field) data in the outer heliosphere and with Helios (plasma) data in the inner heliosphere. We use the Grassberger and Procaccia method that allows calculation of the generalized dimensions of the solar wind attractor in the phase space directly from the cleaned experimental signal. We analyze time series of plasma parameters of the low-speed streams of the solar wind measured in situ by Helios in the inner heliosphere. The resulting spectrum of dimensions shows a multifractal structure of the solar wind attractor. In order to quantify that multifractality, we use a simple analytical model of the dynamical system. Namely, we consider the generalized self-similar baker’s map with two parameters describing uniform compression and natural invariant measure on the attractor of the system. The action of this map exhibits stretching and folding properties leading to sensitive dependence on initial conditions. The obtained solar wind singularity spectrum is consistent with that for the multifractal measure on the weighted baker’s map.     

Complexity,Forced and/or Self-Organized Criticality,and Topological Phase Transitions in Space Plasmas

The first definitive observation that provided convincing evidence indicating certain turbulent space plasma processes are in states of ‘complexity’ was the discovery of the apparent power-law probability distribution of solar flare intensities. Recent statistical studies of complexity in space plasmas came from the AE index, UVI auroral imagery, and in-situ measurements related to the dynamics of the plasma sheet in the Earth's magnetotail and the auroral zone. In this review, we describe a theory of dynamical ‘complexity’ for space plasma systems far from equilibrium. We demonstrate that the sporadic and localized interactions of magnetic coherent structures are the origin of ‘complexity’ in space plasmas. Such interactions generate the anomalous diffusion, transport, acceleration, and evolution of the macroscopic states of the overall dynamical systems. Several illustrative examples are considered. These include: the dynamical multi- and cross-scale interactions of the macro-and kinetic coherent structures in a sheared magnetic field geometry, the preferential acceleration of the bursty bulk flows in the plasma sheet, and the onset of ‘fluctuation induced nonlinear instabilities’ that can lead to magnetic reconfigurations. The technique of dynamical renormalization group is introduced and applied to the study of two-dimensional intermittent MHD fluctuations and an analogous modified forest-fire model exhibiting forced and/or self-organized criticality [FSOC] and other types of topological phase transitions. This revised version was published online in August 2006 with corrections to the Cover Date.