Physical Electron Belt Model from Jupiter's surface to the orbit of Europa

Abstract

The three‐dimensional model, Salammbô‐3D, which was initially developed to model the Earth's radiation belts, has been adapted to Jupiter's radiation environment. As a first step, this model has been validated between L = 1 and L = 6 (L: MacIlwain parameter), just inside Io's obit. In order to extend our three‐dimensional (3‐D) code up to L = 9.5, just inside Europa's orbit, a more realistic magnetic field than the dipole field used before has been introduced in Salammbô. Two magnetic field models are available: The model of Connerney [1981] and the one of Khurana [1997]. Both of them are composed of two parts: An internal magnetic field, intrinsic to the planet, and an external magnetic field, due to the current sheet. Results deduced from Salammbô‐3D, using these two different models, will be shown and compared. Then, to validate our 3‐D code, from Jupiter up to Europa's orbit, comparisons between simulations and two kinds of observations will be done. Firstly, Salammbô results will be compared with spacecraft data (Pioneer 10 and 11) and secondly with radio observations (Very Large Array: VLA). Indeed, with the help of Salammbô‐3D and a synchrotron model, two‐dimensional images of Jupiter's synchrotron emission can be deduced. It is then possible to investigate the global radiation belt shape by comparing simulations and VLA observations. Two important results emerge from this study. First, the extension of our model outside Io's orbit aims to show that Io does not play any role on relativistic electron dynamics, i.e., it does not create losses of particles like the inner moons (Metis, Adrastea, Amalthea, and Thebe). The second important result is that contrary to Io, Europa seems to play a significant role in determining the electron distribution in the Jovian radiation belts.