  Centrifugal instability, which stems from a difference between the azimuthal
angular drift velocity of ions and electrons, is studied in the limit of fast
rotation for which ions can rotate up to twice as fast as electrons. As the
angular velocity approaches the so-called Brillouin limit, the growth rate for
the centrifugal instability in a collisionless solid-body rotating plasma
increases markedly, and is proportional to the azimuthal mode number. For large
wavenumbers, electron inertia effects set in and lead to a cut-off.
Interestingly, conditions for the onset of this instability appear to overlap
with the operating conditions envisioned for plasma mass separation devices.
