  We investigate the conditions for the emergence of wave instabilities in a
vacuum cavity delimited by cylindrical metallic walls under rotation. It is
shown that for a small vacuum gap and for an angular velocity exceeding a
certain threshold, the interactions between the surface plasmon polaritons
supported by each wall give rise to an unstable behavior of the electromagnetic
field manifested in an exponential growth with time. The instabilities occur
only for certain modes of oscillation and are due to the transformation of
kinetic energy into electromagnetic energy. We also study the possibility of
having asymmetric light flows and optical isolation relying on the relative
motion of the cavity walls.
