2D Electron Moments of the Jovian Plasmasheet as Observed by JADE-E

Abstract:

Juno continues to orbit Jupiter and with each inbound pass crosses Jupiter’s equator closer to the planet. 24+ orbits of thermal plasma and magnetometer data are publicly available to date, and ripe for investigating the jovian plasmasheet. The electron sensors on JADE (JADE-E) have undergone inflight cross-calibration and have a background removed in their level 3 version 03 files. These are used to investigate electron moments during the plasma sheet encounters, as identified by the magnetometer data. A reversal in the radial component of magnetic field is used to identify current sheet encounters, while the magnetic field vectors allows JADE-E data to be converted to a pitch angle co-ordinate system to allow 2-dimensional moments (rather than the usual isotropic moments) to be generated.

JADE-E consists of two nearly identical sensors measuring ~0.05 to 100 keV/e electrons. These are mounted along the azimuth of the spacecraft and observe a 2-dimensional slice of phase-space. During high rate science (selected hours near perijove) the sensors are able deflect in spacecraft elevation up to ± 35 degrees in order to track the magnetic field direction, but when in low rate science (most of the middle/outer magnetosphere) there is no deflection so the slice is around a spacecraft elevation of ~0 degrees, which can limit pitch angle coverage and prevent 2-dimensional analysis. However, during current sheet encounters the variation in the magnetic field direction means that full pitch angle coverage is more likely.

Anisotropic electron temperatures can only be calculated with good pitch angle coverage, but where it is possible they will be surveyed. A hot-electron fraction is inferred from the data. We make a preliminary survey of electron properties (e.g. densities, pressures, temperatures) in the Jovian plasma sheet.