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951.
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. 相似文献
952.
Numerical study of magnetic reconnection possibly occurring near heliospheric current sheet 总被引:1,自引:0,他引:1
Fengsi Wei Xueshang Feng Qiang Hu 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2005,36(12):2303-2307
The third-order accurate upwind compact difference scheme has been applied for the numerical study of the magnetic reconnection driven by a plasma blob impacting the heliospheric current sheet, under the framework of the two-dimensional compressible magnetohydrodynamics. The results show that the driven reconnection near the current sheet could occur in about 10–30 min for the interplanetary high magnetic Reynolds number, RM = 2000–10,000, a stable magnetic reconnection structure can be formed in hour order of magnitude, and there appear some basic properties such as the multiple X-line reconnections, vortex structures, filament current systems, splitting and collapse of the high-density plasma blob. These results are helpful in understanding and identifying the magnetic reconnection phenomena possibly occurring near the heliospheric current sheets. 相似文献
953.
本文利用图象分析的方法,将ISEE卫星的等离子体能谱图数值化,以便定量地分析ISEE卫星观测到的磁尾等离子体和磁场资料。以及研究磁尾中性片的纤维结构,对今后研究近地磁尾(22个地球半径以内)各种空间动力学机制,电流结构体系等问题都有很重要的利用价值。 相似文献
954.
955.
采用双波长双脉冲激光全息术,对有激波存在下的空气放电现象进行了研究。建立了双波长电弧折射率场方程,推导出冲击波区的压强同折射率之间的关系式,得出电弧场的压强分布.曲线及等离子体区的温度分布和电子、离子、原子、分子等粒子的数密度分布。 相似文献
956.
A.N. Kryshtal S.V. Gerasimenko A.D. Voitsekhovska 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2012
Process of second harmonics generation due to development of corresponding instability has been investigated for pure electron weakly oblique Bernstein mode. This mode was supposed to be modified by taking into account the influence of pair Coulomb collisions and weak large-scale electric field in flare loop. Investigated area was located near the loop foot-point in the “lower–middle” chromosphere of active region. It has been shown, that for the Fontenla–Avrett–Loeser model of solar atmosphere the investigated process of second harmonics generation starts at the extremely low threshold values of subdreicer electric field, well before the beginning of “preheating” phase of flare process. 相似文献
957.
Baolin Tan 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2007,39(12):1826-1830
The distributing profile of electric current in solar plasma loop is a key factor for the MHD instabilities of the loops. However, it is very difficult to measure such profile in single loop. In this paper, we assume that, in spite of the complexity of the structure in most of the sunspots, the distribution of the electric current in some small simple sunspots may reflect the main feature of the distribution in solar plasma loops. We utilize the high-cadence, high-resolution vector magnetograms observed by Big Bear Solar Observatory (BBSO) to derive the longitudinal electric current and analyze the distribution of the longitudinal electric current in the region of sunspots, and simulate the distributing features of the solar plasma loops. From these analysis, we find that the electric current in some small simple sunspots, or to say in plasma loops, are concentrated to their center. Such distribution feature is consistent with the theory of pinch effect in current-carrying plasma loops. 相似文献
958.
In this paper a heuristic design strategy for stabilizing the satellite attitude has been proposed. It is assumed that the satellite is actuated by a set of mutually perpendicular magnetic coils. Using well-known Lyapunov direct stability method it is shown that the proposed controller causes to a global asymptotic stable system for all near polar orbits. The design procedure is based on analyzing of the conceptual effects of magnetic coils on the satellite attitude motion. Considering these effects lead to some intuitive results which determine the global stabilizing control law. The performance and robustness of the designed controller against actuators saturation and quantization error have been verified using a real-time-hardware–software in-loop (RTHSIL) simulation results. These results show that the global stability can be achieved although some disturbances and restrictions exist. This stabilizing controller can be simply combined with a linear explicit model predictive controller (EMPC) to achieve a full three-axis control law. 相似文献
959.
等离子体气动激励抑制机翼失速分离的实验 总被引:1,自引:0,他引:1
进行了等离子体气动激励抑制机翼失速分离的风洞实验,研究了等离子体气动激励频率、电压、占空比和激励位置等对流动控制效果的影响.研究表明:在来流速度35m/s时,等离子体气动激励可以有效地抑制机翼大攻角下吸力面的流动分离,将机翼临界失速迎角由17°提高到19°;施加激励后,机翼最大升力系数提高了9.45%,阻力系数减小20.9%;激励频率在200Hz时,控制效果最好,对应的量纲一激励频率为1;迎角越大,流动分离越严重,需要更大的激励电压才能够有效抑制流动分离;最佳激励位置在流动分离起始点的前缘;在流动控制效果相当时,减小占空比可以降低能耗. 相似文献
960.
非相似余度作动系统动态力均衡控制策略 总被引:2,自引:2,他引:0
随着多电/全电化飞机关键技术的发展,由功率电传作动器——电动静液作动器(EHA)和机电作动器(EMA)构成的非相似余度作动系统,成为飞机多电/全电化发展的新趋势.介绍了非相似余度作动系统的结构组成和工作原理,建立了非相似余度作动系统力纷争的数学模型.在此基础上,分析了非相似余度作动系统动态力纷争的产生机理,基于上述原理提出了轨迹发生器+前馈补偿器、力纷争反馈PID补偿器和EHA力控制/EMA位置控制等3种减小动态力纷争的动态力均衡控制策略,并对其进行了理论分析与设计.最后,对所提出的3种动态力均衡控制策略进行了仿真对比,并从跟踪动态性能和抗负载扰动动态性能两个方面对仿真结果进行了深入分析.分析结果为非相似余度作动系统的设计和力均衡控制提供了理论依据. 相似文献