Electron-scale magnetic holes filled with high-energy electrons can provide a seed population of electrons in the magnetosphere and might play an important role in the interaction between the magnetosphere and solar wind. Theoretical studies have investigated their generation mechanisms based on the 1D or 2D geometry of the structure. However, the generation mechanism is still unclear. Here we report on the 3D geometry of the electron-scale magnetic hole in the solar wind based on the Magnetospheric Multiscale mission. We find that the cross section of the magnetic hole with a size of ∼0.2–0.6 ρ _i (ion gyroradius) is either circular or 2D sheet-like. Electron vortices exist in both kinds of cross sections. The ellipse is a possible candidate for the geometry of the magnetic hole in the plane including its axis. Surprisingly, such an elliptical geometry suggests that the axial lengths of all our selected magnetic holes are ∼1–2 ρ _i. This 3D geometry might shed some light on the generation mechanism and role of the electron-scale magnetic hole in the astrophysical plasma.

充满高能电子的电子尺度磁空穴可以在磁层中提供电子种子群，并可能在磁层和太阳风之间的相互作用中发挥重要作用。理论研究已经研究了基于结构的一维或二维几何形状的生成机制。然而，其产生机制仍不清楚。在这里，我们报告了基于磁层多尺度任务的太阳风中电子尺度磁孔的 3D 几何形状。我们发现尺寸为∼0.2-0.6 ρ _i的磁孔的横截面(ion gyroradius) 是圆形或二维片状。两种截面都存在电子涡流。椭圆是包括其轴在内的平面中磁孔几何形状的可能候选者。令人惊讶的是，这种椭圆几何形状表明我们选择的所有磁孔的轴向长度为 ∼1–2 ρ _i。这种 3D 几何结构可能对天体物理等离子体中电子尺度磁孔的产生机制和作用有所启发。