Abstract:
In this work, we present a simulation study of equatorial plasma bubble (EPB) in the evening time
ionosphere. The fluid simulation is performed with a high grid resolution, enabling us to probe the
steepened updrafting density structures inside EPB. Inside the density depletion that eventually
evolves as EPB, both density and updraft are functions of space from which the density as implicit
function of updraft velocity or the density distribution function is constructed. In the present study,
this distribution function and the corresponding probability distribution function are found to
evolve from Maxwellian to non-Maxwellian as the initial small depletion grows to EPB. This
non-Maxwellian distribution is of a gentle-bump type, in confirmation with the recently reported
distribution within EPB from space-borne measurements that offer favorable condition for small
scale kinetic instabilities.
