Speaker
Description
Whistler-mode waves play a significant role in scattering energetic electrons within Jupiter's magnetosphere, influencing radiation belt dynamics and auroral precipitation. However, the radial variation of their growth conditions from the dense inner plasma torus to the more tenuous middle magnetosphere has not been systematically explored using recent field and density constraints. This study aims to calculate the linear growth rate of parallel-propagating whistler-mode instability as a function of radial distance between 5 and 40 Jupiter radii. We combine the JRM33 magnetic field model, which provides the background field strength and curvature, with empirically derived electron density profiles based on Juno observations. For the inner region spanning the Io plasma torus, we adopt a multi-component Gaussian model that captures its structured nature. For the outer region extending into the magnetodisk, we employ a power-law profile consistent with recent statistical analyses of Juno plasma data. The transition between these regimes is handled in a straightforward manner. By solving the linear Vlasov dispersion relation assuming a bi-Maxwellian electron distribution, we study the instability growth rate across this radial domain. To isolate the effects of density and magnetic field, we fix other plasma parameters such as thermal velocity and ion-to-electron temperature ratio at typical magnetospheric values, while the magnetic field strength varies with radial distance according to JRM33. The electron cyclotron frequency and plasma frequency are evaluated at each radial step using the background magnetic field and density, respectively. This investigation provides a basic reference for interpreting wave activity observed by Juno and highlights radial locations where whistler-mode generation may be favoured. The results may also serve as a useful input for planning plasma wave analyses for the upcoming JUICE mission.