Magnetic reconnection (MR) is a universal physical process in plasma, in which the stored magnetic energy is converted into high-velocity flows and energetic particles. It is believed that MR plays an important role in many plasma phenomena such as solar fare, gamma-ray burst, fusion plasma instabilities, etc.. The process of MR has been studied in detail by dedicated magnetic-driven experiments. Here, we report the measurements of magnetic reconnection driven by Shenguang II lasers and Gekko XVII lasers. A collimated plasma jet is observed along the direction perpendicular to the reconnection plane with the optical probing. The present jet is very different from traditional magnetic reconnection outflows as known in the two-dimensional reconnection plane. In our experiment, by changing the delay of optical probing beam, we measure the temporal evolution of jet from 0.5 ns to 2.5 ns and its velocity around 400 km/s is deduced. Highcollimated jet is also confirmed by its strong X-ray radiation recorded by an X-ray pinhole camera. With the help of optical interferograms we calculate the jet configuration and its density distribution by using Abel inverting technique. A magnetic spectrometer with an energy range from hundred eV up to one MeV is installed in front of the jet, in the direction perpendicular to the reconnection plane, to measure the accelerated electrons. Two cases are considered for checking the acceleration of electrons. The results show that more accelerated electrons can be found in the reconnection case than in the case without reconnection. We propose that the formation and collimation of the plasma jet, and the electron energy spectrum may be possible directly influenced by the reconnection electric field, which is very important for understanding the energy conversion in the process of MR and establishment of the theoretical model. Finally the electron energy spectra of three different materials Al, Ta and Au are also shown in our work. The results indicate that the higher atomic number material can obtain a better signal-noise ratio, which provides some helpful references for our future work.

利用FOI-PERFECT程序对X箍缩进行了3D数值模拟研究,给出了X箍缩的物理图像和动力学过程,探讨了Z箍缩中出现磁重联的可能性,并指出如果双丝Z箍缩中能够出现磁重联,那么X箍缩是更有利于磁重联出现的位形,并且,X箍缩中出现多重X射线暴的一个可能原因是z轴上多个位置出现磁重联。

用超高速激光纹影技术测量了Z箍缩等离子体磁重联现象。实验采用超高速光电分幅相机，配合激光纹影技术，测量了XP-1装置上两根金属丝产生的等离子体分布，论证了超高速激光纹影技术研究Z箍缩磁重联现象的可行性。双钨丝实验结果表明，电流加载约10 ns后金属丝已有明显膨胀，线性拟合得到平均膨胀速度约8 km/s，金属丝内外两侧出现了规则的极有可能是垂直磁场的电热不稳定性扰动，并沿角向高度关联。铝丝负载的实验结果表明，早期的不稳定性波长为0.4 mm，电流峰值之后金属丝初始位置仍有大量等离子体，后期的不稳定性波长约1.5 mm。这些现象揭示了不稳定性发展的一个主要特征: 短波模式受抑制，长波模式将占主导。

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。

分析了磁重联对晕等离子体加速和能量平衡过程的影响。分析表明晕等离子体向轴心的加速过程分为两个阶段:第一阶段晕等离子体在磁压或热压(依赖于丝数)作用下向轴心运动；第二阶段晕等离子体由于磁重联过程被加速到阿尔芬速度，并到达轴心形成先驱等离子体。估算表明重联层的厚度与离子的惯性长度具有相同的数量级，电流片内电子运动和离子的运动是解耦合的。在内爆滞止阶段电荷分离产生强的径向电场，这个电场将磁能转化为等离子体轴向(z方向)动能，内爆动能和轴向动能共同转化为X射线辐射能，以此解释了X射线能量大于内爆动能这一观测结果。分析了磁重联电磁脉冲的性质，对于1 MA驱动条件，电磁脉冲的总能量可达kJ量级。