JUPITER RADIO-BURSTS AND PARTICLE-ACCELERATION

Particle acceleration processes are important in understanding many of the Jovian radio and plasma wave emissions. However, except for the h igh-energy electrons that generate synchrotron emission following inwa rd diffusion from the outer magnetosphere, acceleration processes in J upiter's magnetosphere and between Jupiter and Io are poorly understoo d. We discuss very recent observations from the Ulysses spacecraft of two new Jovian radio and plasma wave emissions in which particle accel eration processes are important and have been addressed directly by co mplementary investigations. First, radio bursts known as quasi-periodi c bursts have been observed in close association with a population of highly energetic electrons. Second, a population of much lower energy (keV range) electrons on auroral field lines can be shown to be respon sible for the first observation of a Jovian plasma wave emission known as auroral hiss.