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In this work, we consider the dynamics of ion fluxes and magnetic field changes in turbulent regions of magnetotail dipolarizations. The data from the Cluster-II mission (magnetic field measurements from fluxgate magnetometers and energetic charged particle observations from RAPID spectrometers) were used for the analysis. We study individual events and investigate statistically the changes of charged particle fluxes during magnetic field dipolarizations observed during 2001–2015. Received changes in the spectral index indicate that CNO+ ions undergo stronger acceleration during dipolarization than protons and helium ions. Before dipolarization front monotonic growth the ions flux is observed (the maximum of flux is observed at 1–1,5 min after the start of dipolarization) in the range of ∼ 92–374 keV for proton; in the energy range ∼ 138–235 keV for He+ and in the energy range of 414–638 keV for CNO+ ions. Flux increase before arriving dipolarization front may result from the reflection of plasma sheet ions at the dipolarization front and the result of the resonant interactions of ions with low-frequency electromagnetic waves.

In situ plasma measurements as well as remote mapping of energetic neutral atoms around Jupiter provide indirect evidence that an enhancement of neutral gas is present near the orbit of the moon Europa. Simulations suggest that such a neutral gas torus can be sustained by escape from Europa’s atmosphere and consists primarily of molecular hydrogen, but the neutral gas torus has not yet been measured directly through emissions or in situ. Here we present observations by the Cosmic Origins Spectrograph (COS) of the Hubble Space Telescope (HST) from 2020 to 2021, which scanned the equatorial plane between 8 and 10 planetary radii west of Jupiter. No neutral gas emissions are detected. We derive upper limits on the emissions and compare these to modeled emissions from electron impact and resonant scattering using a Europa torus Monte Carlo model for the neutral gases. The comparison supports the previous findings that the torus is dilute and primarily consists of molecular hydrogen. A detection of sulfur ion emissions radially inward of the Europa orbit is consistent with emissions from the extended Io torus and with sulfur ion fractional abundances as previously detected.