  An ultracold electron source based on near-threshold photoionization of a
laser-cooled and trapped atomic gas is presented in this work. Initial DC
acceleration to $\sim$10 keV and subsequent acceleration of the created bunches
to 100 keV by RF fields makes the design suitable to serve as injector for
accelerator-based light sources, single-shot ultrafast protein crystallography,
applications in dielectric laser acceleration schemes, and potentially as an
injector for free electron lasers operating in the quantum regime. This paper
presents the design and properties of the developed DC/RF structure. It is
shown that operation at a repetition frequency of 1 kHz is achievable and
detailed particle tracking simulations are presented showing the possibility of
achieving a brightness that can exceed conventional RF photosources.
