The
unique configuration at Uranus provides both a difficulty and a challenge.
Our studies have been focused on the solar wind interaction. Irena Ruvinsky
and I have a paper(postscript) accepted for publication in JGR which deals with
Alfvén waves near Uranus. Analysis of the ion beam instability near
Uranus shows that the thermal
anisotropy of energetic protons coupled with the relativistic dependence of
their mass
on energy leads to an increase of the resonant Alfvénic wave
growth rate and to a dispersion curve which differs from that of the isotropic
case.
MHD-like waves, excited
by energetic proton beams near the planetary bow shock have (in the
presence of thermal
anisotropy) a dispersion relation similar to that of Alfvén
waves at wavelengths of the order of 
m and can propagate in
the solar wind plasma away from Uranus.