  We report on an unconventional $macroscopic$ field effect transistor composed
of electrons floating above the surface of superfluid helium. With this device
unique transport regimes are realized in which the charge density of the
electron layer can be controlled in a manner not possible in other material
systems. In particular, we are able to manipulate the collective behavior of
the electrons to produce a highly non-uniform, but precisely controlled, charge
density to reveal a negative source-drain current. This behavior can be
understood by considering the propagation of damped charge oscillations along a
transmission line formed by the inhomogeneous sheet of two-dimensional
electrons above, and between, the source and drain electrodes of the
transistor.
