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Editors’ Highlights are summaries of recent papers by AGU’s journal editors.
Source: AGU Advances

In near-Earth space, charged particles and plasma waves can exchange energy most effectively through resonance. Cyclotron resonance is one such interaction, where particles whose gyromotion synchronizes with the wave fields can gain or lose energy from waves, influencing phenomena such as the radiation belts, auroras, and space weather effects that can affect satellites and communication systems.

Li et al. [2026] explore the particular conditions leading to anomalous resonance, which occurs when cyclotron resonance is altered by very large amplitude of plasma waves. The distinguishing contribution of the study is the exploration of anomalous resonance in realistic inhomogeneous environments. The results prove that the interplay of resonances may give rise to an inhomogeneity-driven pathway for energy redistribution across a broader energy range than previously recognized. The above findings provide new insights into a fundamental and previously underappreciated mechanism shaping plasma dynamics across a wide range of space and astrophysical systems.

Ion and electron trajectories in wave field without (left column) and with (right column) background inhomogeneity. Panels (a) and (c) show the trajectories of high- and low-energy ions, respectively, in a uniform background. In panels (b) and (d), the corresponding trajectories are shifted by the background magnetic-field inhomogeneity. This inhomogeneity breaks the trajectory symmetry, enabling a net wave–particle energy transfer. Panels (e) and (f) show the trajectories of low-energy electrons, which are hardly affected by the background inhomogeneity. ζ is the gyro-phase difference between the particle’s perpendicular velocity and the wave magnetic field, and dζ/dt is its rate of change. Credit: Li et al. [2026], Figure 5

Citation: Li, J.-H., Zhou, X.-Z., Wang, S., Liu, Z.-Y., Khotyaintsev, Y. V., Graham, D. B., et al. (2026). Bidirectional energy transfer via simultaneous wave-particle resonances in inhomogeneous space plasmas. AGU Advances, 7, e2026AV002479. https://doi.org/10.1029/2026AV002479

—Alberto Montanari, Editor-in-Chief, AGU Advances

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