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K. Issautier C. Perche S. Hoang C. Lacombe M. Maksimovic J.-L. Bougeret C. Salem 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2005,35(12):2141-2146
We present the solar wind plasma parameters obtained from the Wind spacecraft during more than nine years, encompassing almost the whole solar cycle 23. Since its launch in November 1994 Wind has frequently observed the in-ecliptic solar wind upstream of the Earth’s bow shock. The WIND/WAVES thermal noise receiver was specially designed to measure the in situ plasma thermal noise spectra, from which the electron density and temperature can be accurately determined. We present and discuss histograms of such measurements performed from 1994 to 2003. Using these large data sets, we study the density and core temperature variations with solar activity cycle and with different regimes of the solar wind. We confirm the anticorrelation of the electron density with the sunspot number, and obtain a positive correlation of the core temperature, with the sunspot number. 相似文献
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Turbulent boundary layer separation control using plasma actuator at Reynolds number 2000000 总被引:3,自引:3,他引:0
《中国航空学报》2016,(5):1237-1246
An experimental investigation was conducted to evaluate the effect of symmetrical plasma actuators on turbulent boundary layer separation control at high Reynolds number. Compared with the traditional control method of plasma actuator, the whole test model was made of aluminum and acted as a covered electrode of the symmetrical plasma actuator. The experimental study of plasma actuators' effect on surrounding air, a canonical zero-pressure gradient turbulent boundary, was carried out using particle image velocimetry(PIV) and laser Doppler velocimetry(LDV) in the 0.75 m × 0.75 m low speed wind tunnel to reveal the symmetrical plasma actuator characterization in an external flow. A half model of wing-body configuration was experimentally investigated in the 3.2 m low speed wind tunnel with a six-component strain gauge balance and PIV. The results show that the turbulent boundary layer separation of wing can be obviously suppressed and the maximum lift coefficient is improved at high Reynolds number with the symmetrical plasma actuator. It turns out that the maximum lift coefficient increased by approximately 8.98% and the stall angle of attack was delayed by approximately 2° at Reynolds number2 ×10~6. The effective mechanism for the turbulent separation control by the symmetrical plasma actuators is to induce the vortex near the wing surface which could create the relatively largescale disturbance and promote momentum mixing between low speed flow and main flow regions. 相似文献
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J.S. Haase T. Dautermann M.J. Taylor N. Chapagain E. Calais D. Pautet 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
Equatorial spread-F is a common occurrence in the equatorial ionosphere that is associated with large variations in plasma density that often cause scintillation and interference in communication signals. These events are known to result from Rayleigh–Taylor instability, but the day-to-day variability of their occurrence is not well understood. The triggering mechanism of plasma depletions is still a matter of debate, but may be linked to gravity waves that under favorable conditions propagate to the middle atmosphere. Understanding the triggering of ESF was the focus of the SpreadFEx campaign near Brasilia, Brazil in 2005. The campaign provided co-located airglow and GPS observations to study the onset of plasma depletions and their evolution as they traversed the region. Comparisons between the 630.0 nm airglow data and GPS data demonstrate the ability of the compact dual frequency GPS array to detect the plasma bubbles and retrieve reliable propagation characteristics of the depletions. In this case study, a plasma depletion was detected and moved over the array at velocities of 85–110 m/s, slowing as it moved towards the east. Correlation of consecutive airglow images gives consistent estimates of the eastward drift over the same time period. Mapping the airglow data to the GPS line-of-sight geometry allows direct comparison and reveals a resolvable westward tilt of the plasma depletion that may be due to vertical shear. The uniqueness of this study is the ability to resolve locally the characteristics of the plasma depletion without relying on assumptions about the mapping of the depletion along magnetic field lines to large latitudinal distances. It presents new information for understanding ESF development and the development of depletions strong enough to produce scintillation. 相似文献
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Paul Withers 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009
Recent measurements by Mars Global Surveyor and Mars Express have greatly increased the number of observations of the martian dayside ionosphere available for study. Together with earlier measurements from the Viking era, these datasets have been used to investigate variations in well-known properties of the martian dayside ionosphere and to discover new ionospheric features. The dayside ionosphere includes the main peak, called the M2 layer, and a lower layer, called the M1 layer. In the topside, above the M2 layer, electron densities exponentially decrease with increasing altitude. 相似文献
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Erika M. Harnett Robert M. Winglee 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
The Moon spends 20% of its orbit within the terrestrial magnetosphere. During this time it experiences a dynamic plasma environment, including high-speed streams, flux ropes and a flux of heavy ions from ionospheric outflows. 3D multi-fluid simulations of the Moon within the magnetosphere during a substorm shows that a highly variable plasma flow can develop in the vicinity of the Moon due to the passage of a flux rope. The transit of a flux rope past the Moon potentially leads to a plasma wake that is mis-aligned from the optical wake by nearly 30°. This will have implications when determining the range of space weathering and surface charging the lunar surface experiences. 相似文献
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氧等离子体对空间材料作用的实验研究 总被引:1,自引:0,他引:1
利用制作的射频放电氧等离子体试验装置对单面镀铝Kapton、聚四氟乙烯、聚酯膜、聚酰亚胺、硅橡胶、碳纤维/环氧树脂复合材料、开芙拉,Ag、Cu、Al 箔及OSR(Optical Solar Reflector)等数种空间用材料作了耐氧等离子体性能试验,测量了材料试样在氧等离子体作用后的质量损失、表面电阻率、太阳吸收率α_s和红外辐射率ε等参量,并对试验结果及实用性等问题进行了分析讨论。 相似文献