The efficient containment of molecular and atomic target gases within a geometrically augmented, inertially tethered collision cell was studied. The collision cell incorporates opposed containment jets whose gas flows act as collisional barriers to the escape of a relatively dense target gas in the central region of the cell. For molecular nitrogen and argon gas flows, gains of a factor of 10 have been observed in reducing target gas loss to the high vacuum system over conventional collision cells. Target gas pressures on the order of tens of mT have been contained within the collision cell with acceptable loss to the high vacuum system. Pressure probe measurements have been used to determine the most efficient placement of the containment jet sources with respect to the openings in the collision cell for molecular nitrogen and argon gas containment.