  Photo-ionization of a laser-cooled and compressed atomic beam from a
high-flux thermal source can be used to create a high-brightness ion beam for
use in Focus Ion Beam (FIB) instruments. Here we show using calculations and
Doppler cooling simulations that an atomic rubidium beam with a brightness of
$2.1 \times 10^7 A/(m^2\,sr\,eV)$ at a current of 1 nA can be created using a
compact 5 cm long 2D magneto-optical compressor which is more than an order of
magnitude better than the current state of the art Liquid Metal Ion Source.
