  The performance of a newly built omega type electrostatic analyzer designed
to act as an in-line charge-state purification system for ions in the keV
energy range is reported. The analyzer consists of a set of four consecutive
electrostatic 140{\deg} concentric cylindrical electrodes enclosed by Matsuda
electrodes. This setup was recently tested and validated using $O^{5+}$ ,
$Ar^{9+}$ and $Xe^{20+}$ ion beams at an energy of 14 qkeV at the ARIBE
facility. A resolving power of 10.5 and a transmission of 100 % of the desired
charge state are measured allowing a good purification of incoming ion beams
with charge states up to 10+ and a fairly good purification for charge states
at least up to 20+. In comparison with other in-line solutions such as Wien
filter, our system has the advantage of being purely electrostatic and
therefore lacking common drawbacks as for example hysteresis.
