Plasma-generating device, plasma surgical device, use of a plasma-generating device and method of generating a plasma

1. A plasma surgical device comprising:

an anode, positioned at an outermost distal end of the device,

a cathode;

an electrical insulator sleeve surrounding a substantial portion of the cathode, wherein there is a gap formed by an inside surface of the insulator sleeve and an outside surface of the cathode, the gap being capable of passing a plasma-generating gas; and

one or more intermediate electrodes electrically insulated from each other and from the anode,

one or more of the intermediate electrodes forming a plasma channel having an inlet at a location between the cathode and the anode, the plasma channel extending longitudinally through a hole in the anode and having an outlet opening at a distal end of the anode, the plasma channel having a throttling portion, the throttling portion dividing the plasma channel into

(1) a high pressure chamber positioned upstream of the throttling portion formed by two or more intermediate electrodes and having a first maximum transverse cross-sectional area, and

(2) a low pressure chamber positioned downstream of the throttling portion and having a second maximum transverse cross-sectional area,

the throttling portion having a third transverse cross-sectional area, which is smaller than the first maximum transverse cross-sectional area and the second maximum transverse cross-sectional area.

2. The plasma surgical device of claim 1 , wherein the throttling portion is a supersonic nozzle.

3. The plasma surgical device of claim 2 , wherein the second maximum transverse cross-sectional area is less than or equal to 0.65 mm 2 .

4. The plasma surgical device of claim 3 , wherein the third transverse cross-sectional area is between 0.008 and 0.12 mm 2 .

5. The plasma surgical of claim 4 , wherein the first maximum transverse cross-sectional area is between 0.03 and 0.65 mm 2 .

6. The plasma surgical device of claim 2 , wherein the throttling portion is arranged longitudinally between two of the intermediate electrodes.

7. The plasma surgical device of claim 6 , wherein the throttling portion is arranged longitudinally between (a) at least two of the intermediate electrodes forming a part of the high pressure chamber and (b) at least two of the intermediate electrodes forming a part of the low pressure chamber.

8. The plasma surgical device of claim 2 , wherein a distal end of the cathode has a tapered portion that partially projects beyond a distal end of the insulator sleeve.

9. The plasma surgical device of claim 8 , wherein the throttling portion is a de Laval nozzle.

10. The plasma surgical device of claim 1 , wherein the high pressure chamber is formed by three or more of the intermediate electrodes.

11. The plasma surgical device of claim 1 , wherein the part of the plasma channel being formed by the intermediate electrodes is formed by two or more intermediate electrodes.

12. The plasma surgical device of claim 11 , wherein the part of the plasma channel being formed by the intermediate electrodes is formed by 3-10 intermediate electrodes.

13. The plasma surgical device of claim 1 , wherein the high pressure chamber has a cylindrical portion and the low pressure chamber has a cylindrical portion.

14. The plasma surgical device of claim 1 , wherein one of the intermediate electrodes forms a plasma chamber connected to the inlet of the plasma channel,

wherein a distal end of the cathode extends longitudinally into the plasma chamber to some distance away from the inlet of the plasma channel,

wherein the plasma chamber has a transverse cross-sectional area greater than the first maximum cross-sectional area.

15. The plasma surgical device of claim 14 , wherein the throttling portion is formed by a single of the intermediate electrodes that is distinct from the intermediate electrode forming the plasma chamber.

16. A method of using the plasma surgical device of claim 1 for cutting biological tissue comprising a step of discharging plasma from the outlet of the plasma channel on the biological tissue.

17. The method of claim 16 , wherein the biological tissue is one of liver, spleen, heart, brain, or kidney.

18. The method of claim 16 , wherein the discharged plasma is suitable for cutting biological tissue.

19. The plasma surgical device of claim 1 adapted for use in laparoscopic surgery.

20. A method of generating plasma comprising a step of supplying to the plasma surgical device of claim 1 the plasma-generating gas at a rate of 0.05 to 1.00 l/min, and establishing an electric arc of 4-10 Amperes between the cathode and the anode.

21. The method of 20 , wherein the plasma-generating gas is an inert gas.

22. The method of claim 21 , wherein the plasma-generating gas is argon.

23. The method of claim 20 , wherein the generated plasma creates a static pressure between 3 and 8 bar in the high pressure chamber and a static pressure of up to 3 bar in the low pressure chamber.

24. The method of claim 23 , wherein the electric arc is capable of heating the generated plasma in the high pressure chamber to a temperature between 11,000 and 20,000°C.

25. The plasma surgical device of claim 1 having an outer cross-sectional width of 10 mm or less.