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101.
Vladimir Pines Marianna ZlatkowskiArnon Chait 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2010
We present a general self-consistent kinetic theory for plasma sheath formation in solar wind plasma. The theory could be applied to anisotropic, as well as to isotropic collisionless plasma without resorting to any simplifications, limitations, or assumptions, such as the necessary existence of a ‘pre-sheath’ region of ions acceleration to ensure the Bohm criterion. The kinetic framework is first applied to sheath formation around an arbitrary oriented planar absorbing surface, charged by solar wind anisotropic plasma, under the condition of negligible photoelectric effect. We then make use of our kinetic approach for the plane geometry in isotropic collisionless plasma, as a particular case of a planar electrode orientation parallel to plasma streaming velocity, also analyzing the sheath structure around spherical and cylindrical absorbing electrodes submerged in isotropic collisionless plasma. Obtained results demonstrate principal differences in spatial charge distributions in sheath regions between spherical or cylindrical electrodes of large size and an unbound planar surface submerged in isotropic plasma. In the case of a planar electrode, we directly compare results obtained in our kinetic and hydrodynamic theories and conventional hydrodynamic theory of plasma sheath formation. The outcome from the present study have direct implications to the analysis of plasma sheath structure and associated distribution in space of charged dust grains, which is relevant to the moon exploration near the optical terminator region or in shadowed craters in the moon. 相似文献
102.
Vladimir Pines Marianna ZlatkowskiArnon Chait 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2010
In this paper we study the charging process of small grain particles by anisotropic multi-component solar wind plasmas (electrons, protons and heavy ions), versus two-component (electron/proton) plasmas. We are focusing attention on the important characteristics of the charging process, namely the charging time, floating potential and current content as functions of plasma parameters such as He++/H+ (α/p) number density and Tα/Tp temperature ratios of alpha particles to protons, as well as plasma streaming velocity v0. Measured statistical properties of solar wind plasma parameters at 1 AU show considerable variations in α/p-temperature ratios from 1 to 10, in α/p-number density ratio from 0.01 to 0.35, as well as in values of streaming velocity v0 from 200 km/s to 1000 km/s and more. Periods of these variations could last for several days each, leading to significant variability in the charging process, according to newly derived general analytical expressions. Numerical calculations performed for protons/alphas plasmas showed large disparity in the charging characteristics. For example, in anisotropic plasma, grain charging time varies up to 90% depending on α/p-particles temperature and number density ratios, whereas changes in floating potential are up to 40%. In contrast, in isotropic plasma, charging characteristic for grains do not change very much for the same plasma parameters variations, with charging time varying about 12% and floating potential only varying about 4%. It is also shown that in highly anisotropic plasma, with all ballistic electrons and ions, dust grains could not hold their charges, and characteristic discharged time is calculated. We note that the analysis is equally applicable to any sized body immersed in solar wind plasma. 相似文献
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大迎角分离流场在等离子体控制下的特性研究 总被引:2,自引:0,他引:2
设计了一种新型的大迎角主动流动控制方法。采用圆锥-圆柱组合体模拟飞行器前体,在靠近圆锥尖端处镶嵌了一对马蹄形单电极介质阻挡放电(single_Dielectric Barrier Discharge SDBD)等离子体激励器,通过风洞实验研究了等离子体激励器在不同状态下对大迎角模型前体的非对称气动载荷的控制作用。实验结果表明,通过控制等离子体激励器的开闭可以使得圆锥-圆柱组合体在大迎角下出现的侧力改变方向。还对通过调节单侧等离子体激励器的激励电压实现圆锥前体侧力系数在正负极值间连续变化的可能性进行了初步的实验探索。 相似文献
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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。 相似文献
109.
文章介绍了航天器磁力矩器在低轨道等离子体环境中的一些效应。以某型号卫星为例,计算了某型号磁力矩器产生的磁场,分析了等离子体在磁力矩器产生的磁场中的运动状态。经过建模计算,磁力矩器周围等离子体中的电子将在磁力矩器两端往复运动,而距离磁力矩器较远的电子将聚集在磁力矩器的两端附近。 相似文献
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