Local generation of ULF waves by the Drift-Mirror Instability: observations and theory.

We report on the local generation of an ultra-low frequency (ULF) wave generated by the Drift-Mirror (DM) plasma instability in Earth's inner Magnetosphere [1]. Data analysis, from the Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) onboard NASA's Van Allen Probes Satellites, demonstrates that the DM plasma instability condition for single and multiple particle species is well satisfied. We also demonstrate, for the first time, that the measured wave growth rate agrees well with the predicted linear theory growth rate. Therefore, the in-situ space plasma observations and theoretical analysis demonstrate that local generation of ultra-low frequency and high amplitude plasma waves can occur in the plasma conditions of Earth's inner magnetosphere.

Finally, we present a database summary of measurements of the plasma beta parameter in Earth's inner magnetosphere. We hypothesize that DM instability might be an important ULF wave generation mechanism in Earth's inner magnetosphere.

[1]. Soto-Chavez et.al.,(2019) Phys. Plasmas 26, 042110; https://doi.org/10.1063/1.5083629