A New Framework to Explain Changes in Io's Footprint Tail Electron Fluxes

We analyze precipitating electron fluxes connected to 18 crossings of Io's footprint tail aurora, over altitudes of 0.15 to 1.1 Jovian radii (R-J). The strength of precipitating electron fluxes is dominantly organized by Io-Alfven tail distance, the angle along Io's orbit between Io and an Alfven wave trajectory connected to the tail aurora. These fluxes best fit an exponential as a function of down-tail extent with ane-folding distance of 21 degrees. The acceleration region altitude likely increases down-tail, and the majority of parallel electron acceleration sustaining the tail aurora occurs above 1R(J)in altitude. We do not find a correlation between the tail fluxes and the power of the initial Alfven wave launched from Io. Finally, Juno has likely transited Io's Main Alfven Wing fluxtube, observing a characteristically distinct signature with precipitating electron fluxes similar to 600 mW/m(2)and an acceleration region extending as low as 0.4R(J)in altitude.