  The phenomenon of particle creation within a resonantly vibrating lossy
cavity is investigated for the example of a massless scalar field at finite
temperature. Leakage is provided by insertion of a dispersive mirror into a
larger ideal cavity. Via the rotating wave approximation we demonstrate that
for the case of parametric resonance the exponential growth of the number of
created particles and the strong enhancement at finite temperatures are
preserved in the presence of reasonable losses. The relevance for experimental
tests of quantum radiation via the dynamical Casimir effect is addressed.
