Poynting fluxes, field-aligned current densities, and the efficiency of
the Io-Jupiter electrodynamic interaction
Abstract
Juno’s highly inclined orbits provide opportunities to sample
high-latitude magnetic field lines connected to the orbit of Io, among
the other Galilean satellites. Its payload offers both remote-sensing
and in-situ measurements of the Io-Jupiter interaction. These are at
discrete points along Io’s footprint tail and at least one event (PJ12N)
was confirmed to be on a flux tube directly connecting to Io, allowing
for an investigation of how the interaction evolves down-tail. Here we
present estimated Alfvén Poynting fluxes and field-aligned current
densities along field lines connected to Io and its orbit. We explore
their dependence as a function of down-tail distance and show the
expected decay as seen in UV brightness and electron energy fluxes. We
show that the Alfvén Poynting and electron energy fluxes are highly
correlated and related by an efficiency that is fully consistent with
acceleration from Alfvén wave filamentation via a turbulent cascade
process.