Study Reveals Secondary Instabilities Triggered by EMIC Waves in Earth's Magnetosphere
Researchers used particle simulations and theory to study how electromagnetic ion cyclotron (EMIC) waves interact with cold plasma in Earth's magnetosphere, finding that secondary instabilities can develop even at low wave amplitudes. EMIC waves are common during geomagnetic storms but their effects on cold plasma have been poorly understood due to observational limitations. The findings could improve understanding of plasma heating and particle dynamics in the inner magnetosphere.
A new study published on arXiv examines secondary drift-driven instabilities that occur when parallel-propagating EMIC waves interact with multi-component cold plasma in Earth's inner magnetosphere. Using fully kinetic particle-in-cell simulations combined with linear theory, researchers found that secondary instabilities—including modified two-stream and ion-ion cross-field instabilities—persist even at low EMIC wave amplitudes, provided the cold plasma population remains sufficiently cold. The simulations demonstrate that these secondary modes produce anisotropic heating of cold protons and oxygen ions primarily perpendicular to the magnetic field, while electrons are heated in both directions. While EMIC waves are well-known for scattering hot ions in radiation belts during geomagnetic storms, their interaction with cold plasma has remained poorly characterized, partly due to spacecraft charging effects that limit cold ion observations. This work addresses that gap and may help explain plasma heating mechanisms in the magnetosphere.
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- arXiv physicsCenter
Secondary drift-driven instabilities in the presence of a parallel-propagating electromagnetic ion cyclotron wave and cold multi-component ions
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