  We consider a micromaser model to study the influence of Dicke superradiance
in the context of the one-atom maser. The model involves a microwave cavity
into which two-level Rydberg atoms are pumped in pairs. We consider a random
pump mechanism which allows the presence of at most one pair of atoms in the
cavity at any time. We analyze the differences between the present system,
called the Dicke micromaser, and an equivalently pumped conventional one-atom
micromaser. These differences are attributed to the Dicke cooperativity in the
two-atom system. We also show that the two-atom Dicke micromaser is equivalent
to a one-atom cascade two-photon micromaser. With the introduction of a
one-photon detuning, the present theory further describes a true two-photon
micromaser. We discuss in detail the role of one-photon detuning in the
mechanism of a one-atom two-photon micromaser. This leads us to point out that
the two-atom cavity dynamics can be verified by a proper scaling of the results
from an equivalent one-atom two-photon micromaser.
