A survey of ion cyclotron waves in Jupiter's magnetosphere

Abstract:

Ion cyclotron wave have been observed in the magnetospheres of the Earth, Jupiter, Saturn and in the solar wind upstream of Venus, Mars and several comets. These waves are produced at frequency slightly below the ion cyclotron frequency when the ions have a temperature anisotropy, with the perpendicular temperature greater than the parallel temperature. These waves have been used to investigate both plasma transport, magnetospheric dynamics and the production of fresh ions. In Jupiter’s inner magnetosphere, as observed by the Galileo spacecraft, the necessary temperature anisotropy occurs when neutrals are ionized, and produce a ring or ring-beam distribution in velocity space. This has proven to be a very sensitive measurement of ion production. But in Jupiter's middle and outer magnetosphere, the temperature anisotropy occurs due to plasma transport and conservation of adiabatic invariants, as is the case in Earth's magnetosphere. We present a survey of ion cyclotron waves in Jupiter's magnetosphere, based on our initial analysis of magnetometer data from the Juno spacecraft, and covering the period from orbital insertion in 2016 to late 2019. These results focus on the equatorial region of the outer and middle magnetosphere, which was not observed by Galileo at sufficient time resolution for this such an investigation.