An effector includes a tubular body having a proximal end and a distal end. The effector includes a plug or closure at the distal end of the tubular body; an active electrode at the distal end of the body; an insulator on the body; and one or more return electrodes on the insulator. The body dissipates heat generated by the one or more return electrodes from the distal end of the body to the proximal end of the body.