Speaker
Description
Ionospheric equatorial plasma bubbles/depletions are plasma density irregularities, which tend to develop under specific conditions during post-sunset hours and continue to evolve non-linearly into the post-midnight period. The Rayleigh–Taylor (Kruskal-Shafranov) instability mechanism is believed to be responsible for the formation of these depletions. An intriguing feature of equatorial plasma bubbles is the fact that their electron density energy spectra exhibit a power-law scaling behavior which has been interpreted as evidence of convective turbulence. In fact, if a gravitationally driven Rayleigh–Taylor instability can cause large-scale equatorial plasma bubbles, the E × B gradient drift instability can cause the unstable steep density gradients that form on the sides of equatorial plasma bubbles, resulting in irregularities with size ranging from hundreds of meters to a few kilometers. Here, using data from the Limadou CSES-01 mission, we investigate the character of the turbulent plasma motion inside the plasma bubbles/depletions using high-resolution electric field measurements from the EFD experiment. The results suggest that inside these plasma structures there is evidence for the occurrence of Bolgiano scaling, which would be one of the first evidences for the existence of Bolgiano regime in quasi-2d real convective systems.
