  Various aspects of the phase dynamics of an atom laser scheme based on binary
collisions are investigated. Analytical estimates of the influence of elastic
atom-atom collisions on the laser linewidth are given, and linewidths
achievable in a recently proposed atom laser scheme [Phys. Rev. A 56, 2989
(1997)] are evaluated explicitly. The extent to which a relative phase can be
established between two interfering atom lasers, as well as the properties of
that phase, are also investigated.
