  At temperatures comparable to the Fermi temperature, we have measured a
plasmon enhanced Coulomb drag in a GaAs/AlGaAs double quantum well electron
system. This measurement provides a probe of the many-body corrections to the
coupled plasmon modes, and we present a detailed comparison between experiment
and theory testing the validity of local field theories. Using a perpendicular
magnetic field to raise the magnetoplasmon energy we can induce a crossover to
single-particle Coulomb scattering.
