Figuers 4 and 5 Datasets

We report the recent observation of a density duct structure in the equatorial plasmasphere, identified using data from the NASA Van Allen Probes (RBSP). The structure consists of a low-density duct located above a high-density duct, forming a "double duct" system capable of simultaneously trapping and guiding multiple whistler-mode waves at distinct frequencies. Simulations based on the electron-MHD model confirm that such density double ducts enable efficient confinement and propagation of whistler-mode waves along the background magnetic field.本研究报道了近期在赤道等离子体层中发现的密度导管结构，该结构通过美国国家航空航天局（National Aeronautics and Space Administration, NASA）范艾伦探测器（Radiation Belt Storm Probes, RBSP）的观测数据得以识别。该结构由位于高密度导管上方的低密度导管组成，形成一套“双导管”系统，可同时在不同频率下捕获并导引多种哨声模波（whistler-mode waves）。基于电子磁流体动力学（electron-MHD）模型开展的模拟结果证实，此类密度双导管能够实现哨声模波沿背景磁场的高效约束与传播。