【摘要】 激光等离子体磁重联实验再现了卫星观测到的日地磁场活动特征。一方面,实验再现了太阳冕区物质抛射及耀斑结构,包括明亮的尖屋顶状环、具有微细结构的磁化等离子体团以及二者之间因为磁场拉扯而产生的二阶电流片。另一方面,实验发现存在三个电子扩散区(EDR),这与欧洲空间局Cluster卫星先后在2003年和2005年发现的分别处于地磁尾重联区中间部位及两侧分形线位置的两类EDR结构相似。所不同的是,在激光等离子体磁重联实验中,两类EDR在一次重联过程中产生,但中心EDR出现时间晚于两侧EDR,且其发展速度更快,喷流速度接近或者超过迎流Alfven速度。通过对太阳耀斑附近、地磁尾重联区以及激光等离子体自生磁场重联区位置等离子体的参数比较,显示三者在一定程度上具有Euler-Alfven相似性,这表明可以通过激光等离子体自生磁场的重联过程来研究其他两种等离子体中的磁重联现象。更多还原

【Abstract】 Laser-plasma experiments about magnetic reconnection have been used to investigate characteristics of activities of the solar magnetic field and the magnetosphere.In our recent laser plasma experiments,two side-byside thin target layers,instead of a single one,are used.It is found that at one end of the elongated current sheet(CS),a fanlike electron outflow region including three well-collimated electron jets appears.These laboratory experimental observations of three electron diffusion regions(EDRs)reproduce the characteristics of magnetic reconnection sites at the Earth’s magnetotail,which was observed by the Cluster satellites in 2003and 2005,separately.The higher than 1 MeV tail of the jet energy distribution exhibits a power-law scaling.The enhanced electron acceleration is attributed to the intense inductive electric field in the narrow electron dominated reconnection region,as well as additional acceleration as electrons are trapped inside the rapidly moving plasmoid formed in and ejected from the CS.The plasmoid ejection also induces a secondary CS.The experimental results mimic the formation process of solar coronal mass ejections and flares,and also confirm the theory and model predictions about the CS-born anomalous plasmoid as the initial stage of coronal mass ejections,and the behavior of moving-away plasmoid stretching the primary reconnected field lines into a secondary CS conjoined with two bright ridges identified.We compare the parameters of plasmas in the transition region between solar corona and chromosphere,at the reconnection site of the magnetotail,and that produced by the giant lasers,and find that all three plasma systems have Euler-Alfven similarity,meaning that the physics underlying current laser-plasma phenomena can be applicable to that of solar flares and substorms of magnetosphere.更多还原