The present invention is an ablation device having a screen sphere configuration for the ablation of marginal tissue surrounding a tissue cavity. The device includes a probe having a nonconductive elongated shaft including at least one lumen therethrough and a nonconductive distal portion extending from the shaft. The nonconductive distal portion includes a plurality distal ports and a plurality of proximal ports in communication with the at least one lumen of the shaft. The device further includes an electrode array including a plurality of independent conductive wires extending through the lumen and positioned along an external surface of the nonconductive distal portion, each of the plurality of wires passes through at least an associated one of the proximal ports and through at least a corresponding one of the distal ports.
