Tissue ablation systems

Apparatus for applying energy to a tissue surface, said apparatus comprising:

• a probe body having a support end, a working end, and a thin elastic dielectric wall surrounding an interior chamber disposed about the working end, said thin elastic dielectric wall preventing formation of a direct electrically conductive path from the plasma to the tissue surface;
• a frame which supports the dielectric wall, said frame being expandable and contractable to open and close the dielectric wall;
• a gas inlet on the probe body adapted to be connected to deliver an electrically non-conductive gas to the interior chamber;
• a first electrode structure having a surface exposed to the interior chamber and/or the gas inlet;
• a second electrode structure on an exterior surface of the probe body, said second electrode structure having a surface adapted to contact tissue;
• a radiofrequency power supply adapted to apply a radiofrequency voltage across the first and second electrode structures, wherein the voltage is sufficient to initiate a plasma in the electrically non-conductive gas within the interior chamber and to capacitively couple current in the plasma across the dielectric wall to thereby apply energy to the tissue.