摘要
利用神光Ⅱ激光器和日本大阪大学Gekko激光器构建了激光驱动等离子体磁重联过程.在垂直于磁重联平面方向发现了高速喷流,从不同观测方向实验证实了该喷流的存在并测量了喷流的流体力学演化过程,对其中的电子能谱进行了诊断分析.
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. High- collimated 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 reconnectioncase 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 A1, 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.
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2015年第16期317-323,共7页
Acta Physica Sinica
基金
国家重点基础研究发展计划(批准号:2013CBA01503)
国家自然科学基金(批准号:11205015
11273033
11135012)
北京科技新星(批准号:Z131109000413050)资助的课题~~
关键词
磁重联
电子加速
magnetic reconnection, electron acceleration
