An ablation electrode system includes a handle assembly； a needle electrode assembly supported in and extending from the handle assembly. The needle electrode assembly includes an outer tube having at least a conductive distal tip and defining a cavity therein； and an inner tube disposed at least partially within the cavity of the outer tube and defining a lumen therein. The ablation electrode assembly includes a hub assembly fluidly connected to the needle electrode assembly. The hub assembly defines a first chamber and a second chamber； wherein the proximal end portion of the inner tube is in fluid communication with the first chamber and the proximal end portion of the outer tube is in fluid communication with the second chamber. The ablation electrode assembly includes a first fluid conduit fluidly connected to the first chamber； and a second fluid conduit fluidly connected to the second chamber.
