  Based on a recent theory (Coppi, Nuclear Fusion, 42, 1, 2002) of spontaneous
toroidal rotation in tokamaks (Lee et al, Phys Rev Lett, 91, 205003, 2003) and
in astrophysical accretion disks, we propose that an analogous process could be
at play also in the Earth space environment. We use fully kinetic PIC
simulations to study the evolution of drift instabilities and we show that
indeed a macroscopic velocity shear is generated spontaneously in the plasma.
As in tokamaks, the microscopic fluctuations remain limited to the edge of the
plasma channel but the momentum spreads over the whole macroscopic system.
