A plasma cell for controlling convection includes a transmission element configured to receive illumination from an illumination source in order to generate a plasma within a plasma generation region of the volume of gas. The plasma cell also includes a top flow control element disposed above the plasma generation, which includes an internal channel configured to direct a plume of the plasma upward, and a bottom flow control element disposed below the plasma generation region, which includes an internal channel configured to direct gas upward toward the plasma generation region. The top flow control element and the bottom flow control element are arranged within the transmission element to form one or more gas return channels for transferring gas from a region above the plasma generation region to a region below the plasma generation region.