近日太阳风中磁场回弯结构的MHD模拟

帕克太阳探针(Parker Solar Probe，PSP)在太阳附近发现大量磁力线回弯结构，通常还伴随有太阳风速度增加.这些磁力线回弯的产生机制到目前为止有多种解释，其中有代表性的一种是由慢太阳风中的喷流引起的.我们首先对PSP的就地观测数据进行了统计分析并给出了发生率和空间尺度随径向距离的演化情况，然后使用简化的1.5维磁流体动力学(magnetohydrodynamics，MHD)模型对喷流在太阳风中的演化进行了模拟，其中太阳风被简化为位于黄道面的球对称流.模拟结果表明喷流的确可以导致太阳附近磁力线发生偏转，验证了喷流可以对磁场方向改变有贡献的图景.不过喷流形成的原因还需要进一步研究.

An MHD simulation of magnetic switchbacks in the near-Sun solar wind

Although lots of magnetic field switchbacks have been observed near the sun using Parker Solar Probe (PSP) observations, the physical mechanisms leading to switchbacks are still under discussion. Jets was first suggested as main causes of switchbacks, later other magnetic physical processes including reconnection were also proposed to explain them. We first perform a statistical analysis on switchback events observed by PSP, then simulate the propagation of jets in the solar wind using a numerical magnetohydrodynamics (MHD) model. The observed evolution of occurrence rate and spatial scale with radial distance match well with the simulation. The simulation also shows that jets lead to the magnetic field deflection near the sun. Therefore we conclude that jets are main causes to magnetic field switchbacks. However, the formation of jets needs further study in the future.