  We demonstrate an intense, continuous cold atom beam generated via post
nozzle seeding of a supersonic helium jet with $^7$Li atoms. The nozzle is
cooled to about 4.4 K to reduce the forward velocity of the atoms. The atomic
beam is brought to a focus 175 cm from the nozzle by a 10 cm bore diameter
magnetic hexapole lens. Absorption and fluorescence imaging of the focus show a
flux of $2.3(4) \times 10^{12}$ atoms/s, brightness of $4.1(7)\times 10^{19}$
$\textrm{m}^{-2}\textrm{s}^{-1}\textrm{sr}^{-1}$, forward velocity of 211(2)
m/s, and longitudinal temperature of 7(3) mK. Results agree with a Monte Carlo
simulation of the seeding dynamics and a particle tracing simulation of the
atom lens. We project that 10 times higher flux would be possible with improved
vacuum system design. Our method should provide a useful high-brightness source
for atom-optical and other atomic and molecular physics applications.
