Plasma properties in the deep jovian magnetotail

摘要

New Horizons observed consistently and continuously the jovian magnetotail at distances up to 2500 Jupiter Radii (Ri) during its Jupiter flyby in 2007. The Solar Wind Around Pluto (SWAP) plasma instrument on New Horizons made in situ observations of plasma ions in the energy per charge range of similar to 21 eV to 7.8 keV. We analyze the SWAP plasma observations and derive the bulk properties of the plasma ions in the deep jovian magnetotail for 64 intervals from 500 to 1700 R-j, just before the spacecraft start crossing the jovian magnetopause. There is no clear evolution of the plasma parameters over this distance range and we show that the plasma is very diverse over this entire range. There are significant changes in the plasma parameters and the flow direction over times as short as a few hours, showing evidence that boundaries between different plasma structures pass over the spacecraft rapidly. We discuss in detail a few subintervals where two species are observed within the instrument's energy per charge range and a set of subintervals where the plasma flow rotates 20 over just six hours. We finally discuss the mass flux during the subintervals we study and the scenario of expanding plasmoids that propagate tailward and expand and interact to fill the magnetotail. This scenario is supported by the observed plasma diversity and flow characteristics. (C) 2015 Elsevier Ltd. All rights reserved.