  In this paper we discuss the design and performance of a collimated Knudsen
source which has the benefit of a simple design over recirculating sources.
Measurements of the flux, transverse velocity distribution and brightness at
different temperatures were conducted to evaluate the performance. The scaling
of the flux and brightness with the source temperature follow the theoretical
predictions. The transverse velocity distribution in the transparent operation
regime also agrees with the simulated data. The source was found able to
produce a flux of $10^{14}$ s$^{-1}$ at a temperature of 433 K. Furthermore the
transverse reduced brightness of an ion beam with equal properties as the
atomic beam reads $1.7 \times 10^2$ A/(m${}^2$ sr eV) which is sufficient for
our goal: the creation of an ultra-cold ion beam by ionization of a
laser-cooled and compressed atomic rubidium beam.
