[en] An experiment on centrifugal separation of a He-Ar mixture gas has been performed in a weakly ionized rotating plasma. The concentration of Ar to He at the outer electrode has increased with increasing the axial magnetic field or radial current, and has reached the level 1.55 times larger than that before rotation when the magnetic field is 7.5 kG and the total electric current is 1.0 A. This result does not depend on the gas pressure from 0.6 to 20 Torr. A possible application of this device to uranium isotope separation is discussed. (author)