Dynamic three-wave coupling between local sporadic spokes and emergence of global breathing oscillation in partially magnetized cross-field plasmas

Localized small-scale events can influence the global behavior of physical systems in unexpected ways. In partially magnetized plasmas, how localized wave interactions drive large-scale oscillations remains unclear. Here we present experimental evidence that intermittent three-wave coupling between rotating structures leads to a low-frequency breathing oscillation. This oscillation emerges from nonlinear interactions between two coherent spokes with distinct mode numbers. Frequency spectrograms from fast imaging and discharge current signals reveal that these interactions push the system into a nonlinear regime, where both small- and large-amplitude spokes dynamically appear and vanish. During this regime, global light emission decreases as large spokes grow. We also observe energy transfer between local spokes and the global breathing mode, suggesting that the oscillating azimuthal electric field contributes to additional ionization. These findings reveal a coupling between local and global plasma dynamics and may guide future efforts to improve stability and confinement in plasma sources. Localized small-scale events in plasmas can trigger significant large-scale effects, posing challenges in fields like fusion energy and space propulsion. The authors provide experimental evidence of intermittent three-wave coupling in. We have reviewed the draft summary and approve it as written. Partially magnetized plasmas, revealing nonlinear interactions that drive a global breathing oscillation, advancing our understanding of plasma stability and confinement.