  We demonstrate a \SI{650}{\mW} \SI{243}{\nm} continuous-wave laser coupled to
a linear optical enhancement cavity. The enhancement cavity can maintain
$>$\SI{30}{\W} of intracavity power for \SI{1}{\hour} of continuous operation
without degradation. This system has sufficient power for a demonstration of
two-photon laser cooling of hydrogen and may be useful for experiments on other
simple two-body atomic systems.
