Derivation of ions bulk properties in the deep Jovian magnetotail beyond 200Rj

Abstract:

New Horizons flew by Jupiter during 2007 and was the first spacecraft to obtain measurements in the deep Jovian magnetotail beyond 200 R_j. We analyze 50 spin-angle spectrograms obtained by Solar Wind Around Pluto (SWAP) instrument onboard New Horizons (NH) during the Jupiter encounter in order to derive the plasma ions bulk properties in this region. We excluded the observations in the Jovian boundary layer and the magnetosheath since they were analyzed in our previous studies. Here, we explain our methodology and we present our results. We show that the Jovian magnetotail has very diverse plasma populations. All of the bulk parameters of the observed plasma vary significantly within few hours. The plasma dynamic and thermal pressure varies by ~2 orders of magnitude during the magnetotail observations. In many subintervals, the non-tailward component of the flow direction is the major component. In some other cases, there is a clear tailward and very fast (~800 kms^-1) flow of cold (~10eV) plasma. Finally, we isolate some subintervals to identify consistent changes in the plasma flow so we can then relate them to physical mechanisms that take place in the deep Jovian magnetotail.