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首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >Counterstreaming electrons in magnetic clouds
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Counterstreaming electrons in magnetic clouds

机译：逆流磁性云中的电子

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Two widely used signatures of interplanetary coronal mass ejections are counterstreaming suprathermal electrons, implying magnetic structures connected to the Sun at both ends, and magnetic clouds, characterized by large-scale field rotations, low temperature, and high field strength. In order to determine to what extent these signatures coincide, electron heat flux data were examined for 14 magnetic clouds detected by ISEE 3 and IMP 8 near solar maximum and 34 clouds detected by Wind near solar minimum. The percentage of time during each cloud passage that counterstreaming electrons were detected varied widely, from 6 clouds with essentially no counterstreaming to 8 clouds with nearly 100% counterstreaming. All of the former but less than half of the latter occurred near solar minimum, suggesting a possible solar cycle dependence on the degree of magnetic openness. The counterstreaming intervals were distributed randomly throughout the clouds, with a median length of 2.5 hours. A plot of counterstreaming percentages against cloud diameter for 33 clouds modeled as cylindrical flux ropes indicates a linear dependence of the percentage of closed flux on cloud size, with the largest clouds being the most closed. Overall the results are consistent with the view that although magnetic field lines within a magnetic cloud can form a large-scale, coherent structure, reconnection in remote regions of the structure, presumably near the Sun, sporadically alters its topology fi om closed to open until the cloud assimilates into the ambient solar wind. [References: 33]
机译：行星际日冕物质抛射的两个广泛使用的特征是逆流超热电子，这意味着两端都与太阳相连的磁性结构，以及磁云，其特征是磁场旋转大，温度低，磁场强度高。为了确定这些特征在多大程度上重合，检查了由ISEE 3和IMP 8探测到的接近太阳最大值的14个磁云和由Wind探测到太阳最小值附近的34个云的电子热通量数据。在每个云通道通过期间检测到逆流电子的时间百分比变化很大，从6个基本没有逆流的云到8个几乎逆流100％的云。前者全部但少于后者的一半发生在太阳极小值附近，这表明太阳周期可能取决于磁开放度。逆流间隔是随机分布在整个云中的，平均长度为2.5小时。以圆柱状通量绳为模型的33个云的逆流百分比相对于云直径的图表明，封闭通量百分比对云尺寸的线性相关性，最大的云为最大的云。总体而言，结果与以下观点一致：尽管磁云内的磁力线可以形成大规模的，连贯的结构，但在结构的偏远区域（大概在太阳附近）的重新连接会偶尔改变其拓扑结构，使其从封闭状态变为打开状态直到云团吸收到周围的太阳风中。 [参考：33]

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