国家自然科学基金项目(11933009), 中国科学院项目(XDA17040507、XDA15010900、QYZDJ-SSWSLH012), 云南省创新团队基金项目(2018HC023), 云南省``高层次人才培养支持计划-云岭学者''专项资助
1. Yunnan Astronomical Observatory, Chinese Academy of Sciences, Kunming 650011;2. University of Chinese Academy of Sciences, Beijing 100049;3. Department of Astronomy, Beijing Normal University, Beijing 100875;4. Center for Astronomical Mega-Science, Chinese Academy of Sciences, Beijing 100012;
激光驱动亥姆霍兹电容线圈靶的磁重联实验已经提出并进行了多年. 当实验中的金属板被强激光照射时产生自由电子, 这些自由电子的运动在连接两金属板的两个平行线圈中产生电流, 由两个平行线圈内部电流产生的磁场之间随即发生重联. 该实验不同于其他直接由Biermann电池效应所产生高beta (等离子体热压与磁压的比值)环境下的磁重联实验. 对该类实验进行了3维磁流体动力学数值模拟, 首次展示了亥姆霍兹电容器线圈靶如何驱动磁重联的过程. 数值模拟结果清楚地表明, 磁重联的出流等离子体在线圈周围发生与实验结果相一致的堆积现象. 线圈电流产生的磁场可高达100T, 使得磁重联区域周围的等离子体beta值达到10-2. 与实验室结果进行比较, 数值模拟重复了实验展示的大多数特征, 可有助于深入认识和理解实验结果背后的物理学原理.
Experiments of magnetic reconnection driven by the laser in laboratory with the Helmholtz capacitor-coil target have been carried out for years. In the experiment, the reconnecting magnetic fields are induced by the electric current inside two conjugate coils. The electric current results from the flow of free electrons between two metal plates connecting to one another via two coils, and free electrons are produced as one of the metal plate is irradiated by the intense laser. This kind of experiments of reconnection differs from others that perform the reconnection process with the magnetic field produced directly by the Biermann battery effect. The three-dimensional numerical experiments in the magnetohydrodynamical framework to show for the first time how the reconnection process is driven by the laser with the Helmholtz capacitor-coil target. The numerical simulation results indicate clearly that the outflow plasma of magnetic reconnection shows characteristic accumulation around the coils. In addition, the reconnecting magnetic field produced by the induced electric current inside the coils could be as strong as 100 T, and the plasma beta (the ratio of the thermal energy density to the magnetic energy density) around the reconnection region is around 10-2. Comparisons with the existing results of the laboratory experiments suggest that the numerical experiment duplicate most features of the laboratory experiments, which helps examine the physics behind the phenomena shown by the laboratory experiments.