The Plasma Physics of the Jovian Decameter Radiation

Abstract

We have assumed that the decameter radiation from Jupiter is produced near the local electron gyrofrequency and is amplified as it propagates out of the Jovian magnetosphere. Using the VlasovMaxwell equations, which describe the propagation of radiation in hot collisionless plasmas, we have derived the growth rate for radiation that propagates almost perpendicular to the direction of the magnetic field. When the electrons are described by a loss-cone distribution function, the growth rate is large enough to lead to a large amplification factor over a source region of 100-4000 km, depending on the choice of parameters. Because we expect low-energy electrons to be trapped in the Jovian dipole field regardless of the position of the satellite lo, we maintain that this model provides a plausible mechanism for the decametric radiation not associated with lo.