Van Allen Probes in situ observations are used to examine detailed subpacket structure observed in strong VLF (very low frequency) rising-tone chorus elements observed at the time of a rapid MeV electron energization in the inner magnetosphere. Analysis of the frequency gap between lower and upper chorus-band waves identifies f_ceEQ, the electron gyrofrequency in the equatorial wave generation region. Initial subpackets in these strong chorus rising-tone elements begin at a frequency near 1/4 f_ceEQ and exhibit smooth gradual frequency increase across their > 10 ms temporal duration. A second much stronger subpacket is seen at frequencies around the local value of 1/4 f_ce with small wave normal angle (< 10°) and steeply rising df/dt. Smooth frequency and phase variation across and between the initial subpackets support continuous phase trapping of resonant electrons and increased potential for MeV electron acceleration. The total energy gain for individual seed electrons with energies between 100 keV and 3 MeV ranges between 2 and 15%, in their nonlinear interaction with a single chorus element.

范艾伦探针原位观测用于检查在内磁层中快速 MeV 电子激励时观察到的强 VLF（极低频）上升音合唱元素中观察到的详细子包结构。对下合唱带波和上合唱带波之间的频率间隙的分析确定了f _ceEQ ，即赤道波生成区域中的电子陀螺频率。这些强合唱升调元素中的初始子包以接近 1/4 f _{ceEQ 的}频率开始，并在其 > 10 ms 时间持续时间内表现出平滑的逐渐频率增加。第二个更强的子包出现在 1/4 f _ce局部值附近的频率处，具有小波法向角 (< 10°) 和急剧上升的 d f /d t 。初始子包之间的平滑频率和相位变化支持谐振电子的连续相位捕获并增加 MeV 电子加速的潜力。能量在 100 keV 到 3 MeV 之间的单个种子电子在与单个合唱元素的非线性相互作用中的总能量增益在 2% 到 15% 之间。