NOVELTY - The reactor comprises a furnace, a crucible (110), a downtube, a spool structure, a flow diversion structure, a porous disc structure, and a splash guard. The crucible is positioned for heating by the furnace, and defines an interior volume. The downtube is disposed partially within the interior crucible, and includes a conduit having an inlet at a first end, an outlet at a second end and openings formed between the first end and the second end. The outlet and opening are configured to provide a recirculation path for any liquid material contained within the crucible.    USE - The reactor is useful in a gas processing system (claimed) for extracting an energy source such as hydrogen or other gases from a given material, where the reactor includes an alkaline metal reactor.    ADVANTAGE - The reactor energy efficiently, simply and economically extracts the energy source from the given material in an environmental friendly manner.    DETAILED DESCRIPTION - The reactor comprises a furnace, a crucible (110), a downtube, a spool structure, a flow diversion structure, a porous disc structure, and a splash guard. The crucible is positioned for heating by the furnace, and defines an interior volume. The downtube is disposed partially within the interior crucible, and includes a conduit having an inlet at a first end, an outlet at a second end and openings formed between the first end and the second end. The outlet and opening are configured to provide a recirculation path for any liquid material contained within the crucible. The openings are tapered at one end of the conduit. The downtube extends along a longitudinal axis of the crucible. A cross-sectional area of the downtube, as taken perpendicular to the longitudinal axis, is half of a cross-sectional area of the crucible as taken perpendicular to the longitudinal axis. The downtube further includes guide members that are coupled with the conduit and are sized and positioned to maintain the conduit along the longitudinal axis. The spool structure is coupled with the crucible, and includes an outlet (126) and an inlet (130). The inlet of the conduit is present in fluid communication with the inlet of the spool structure. The flow diversion structure is positioned adjacent to the second end of the conduit, exhibits a spherical geometry, and is spaced apart from the second end of the conduit. Each of the guide members is coupled between the conduit and the flow diversion structure. The crucible further includes a reactant inlet positioned below the second end of the conduit. The porous disc structure is positioned between the reactant inlet and the second end of the conduit. The splash guard is coupled with the conduit and positioned between the opening and the first end of the conduit. The furnace includes selectively controllable heating zones. The crucible and the downtube are formed from a stainless steel material. INDEPENDENT CLAIMS are included for:    (1) a gas processing system;    (2) a downtube; and    (3) a method for controlling a reaction within a reactor.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic view of a reactor.    Crucible (110)    Frame (114)    Flange (122)    Outlet of spool structure (126)    Inlet of spool structure. (130)