  We report on a two-fold increase of the $^{39}Ar$ loading rate in an atom
trap by enhancing the generation of metastable atoms in a discharge source.
Additional atoms in the metastable $1s_5$ level (Paschen notation) are obtained
via optically pumping both the $1s_4$ - $2p_6$ transition at 801 nm and the
$1s_2$ - $2p_6$ transition at 923 nm. By solving the master equation for the
corresponding six-level system, we identify these two transitions to be the
most suitable ones and encounter a transfer process between $1s_2$ and $1s_4$
when pumping both transitions simultaneously. We calculate the previously
unknown frequency shifts of the two transitions in $^{39}Ar$ and confirm the
results with trap loading measurements. The demonstrated increase in the
loading rate enables a corresponding decrease in the required sample size,
uncertainty and measurement time for $^{39}Ar$ dating, a significant
improvement for applications such as dating of ocean water and alpine ice
cores.
