| 摘要 |
An electrosurgical instrument generates a plasma to perform surface coagulation and emits a non-ionising microwave field to perform coagulation within tissue. A probe tip 510 is connected to a coaxial cable 502 to receive radio frequency and/or microwave energy from a generator, with a first electrode connected to the inner conductor 504 of the cable and a second electrode connected to the outer conductor 506. A sheath 514 surrounds the cable and provides an annular passage 516 for gas. The probe tip is preferably adjustable between a first, bipolar configuration (figure 12A) to strike and sustain plasma, and a second configuration (figure 12B) with the first electrode displaced distally as a monopole antenna. The first electrode is preferably a cylinder of dielectric with a hemispherical end, the inner conductor of the cable running through it and protruding distally. The outer conductor of the cable is connected to the second electrode by an electrically conductive, gas permeable structure such as a cage of wires. The second electrode may be a conductive tube 518 with internal projections 520 to contact the outer conductor of the cable. |
