Electrosurgical method and apparatus for initiating an electrical discharge in an inert gas flow

• US 4,040,426 A
• Filed: 01/16/1976
• Issued: 08/09/1977
• Est. Priority Date: 01/16/1976
• Status: Expired due to Term

• Current Assignee: Valleylab Inc. (Medtronic Plc)
• Original Assignee: Valleylab Inc. (Medtronic Plc)
• Inventors: Morrison, Charles F. Jr.
• Primary Examiner(s): Michell, Robert W.
• Assistant Examiner(s): Thaler, Michael H.
• Application Number:
  US05/649,682
• Time in Patent Office: 571 Days
• Field of Search: 128/303.1, 128/303.17, 128/303.14, 128/303.13, 128/DIG. 22, 219/121 P, 219/75
• US Class Current: 606/49
• CPC Class Codes: A61B 18/042 using additional gas becoming plasma
• CPC Class Codes: A61B 18/1402 Probes for open surgery
• CPC Class Codes: B23K 9/167 and of a non-consumable electrode
• CPC Class Codes: H01T 1/00 Details of spark gaps
• CPC Class Codes: H05H 1/32 using an arc H05H1/28 takes precedence

Abstract

A method and apparatus for initiating an electrical discharge in a formation of flowing inert gas disposed adjacent the end of an active electrode by generating charged particles in the vicinity of said inert gas formation. The charged particles are generated by an auxiliary electrical discharge produced between the active electrode and a surrounding tube, which is not connected to any external source of biasing potential. Electrostatic charge is generated on the tube as the inert gas flows thereby. This charge bleeds off the tube through inwardly pointed tips on the tube, which act as discharge points. The charge then passes to the active electrode via the auxiliary discharge through the gas.

Claims

1. Apparatus for establishing an electrical discharge to an object comprising

a support;

a source of electrical energy;

an active electrode connected to said source of electrical energy and being supported by said support and outwardly extending therefrom;

a source of inert gas;

gas flow directing means connected to said source of inert gas for directing the gas past said electrode to thereby facilitate the establishment of a primary electrical discharge in the gas disposed adjacent the end of the electrode and extending outwardly therefrom;

discharge initiating means disposed adjacent to said electrode for initiating said electrical discharge in said gas formed adjacent the end of the electrode, said discharge initiating means including said active electrode and a second electrode having a small gap therebetween, across which an auxiliary discharge initiates said primary electrical discharge;

said second electrode being electrically isolated from any source of biasing potential and being so disposed in the gas flow established by said gas flow directing means that said gas generates electrostatic charge on said second electrode, which is discharged through said gas to said active electrode to thereby establish said auxiliary electrical discharge; and

means for returning said electrical energy from said object to said source of electrical energy.

2. Apparatus as in claim 1 where said second electrode is an electrically conductive tube disposed about and surrounding said active electrode.

3. Apparatus as in claim 2 where said second electrode includes at least one inwardly directed, pointed projection extending from said tube whereby said auxiliary discharge occurs between said pointed projection and said active electrode.

4. Apparatus as in claim 1 including an electrically conductive tube connected to said source of inert gas, through which said gas flows, said tube also being connected to said source of electrical energy at one end thereof and to said active electrode at the other end thereof.

5. Apparatus as in claim 1 where said second electrode is an electrically conductive tube which is substantially collinearly disposed with respect to said active electrode so that said gas first flows by said tube to generate said electrostatic charge thereon and then it flows past said active electrode.

6. Apparatus as in claim 5 where said active electrode is tubular.

7. Apparatus as in claim 6 where the tubular active electrode includes at least one projection extending therefrom whereby said auxiliary discharge occurs between said pointed projection and said active electrode.

8. Apparatus as in claim 1 where said discharge initiating means includes at least one pointed projection extending from at least said second electrode.

9. Apparatus as in claim 1 where said discharge initiating means includes at least one pointed projection extending from at least said active electrode.

10. An instrument comprising

a support;

an active electrode supported by said support and outwardly extending therefrom;

gas flow directing means adapted for the directing of gas past said electrode to provide gas adjacent the end of the electrode and extending outwardly therefrom; and

discharge initiating means disposed adjacent to said electrode adapted for the initiation of a primary electrical discharge in said gas formed adjacent the end of the electrode, said discharge initiating means including said active electrode and a second electrode having a small gap therebetween, across which an auxiliary discharge initiates said primary electrical discharge;

said second elctrode being electrically isolated from any source of biasing potential and being so disposed in the gas flow established by said gas flow directing means that said gas generates electrostatic charge on said second electrode, which is discharged through said gas to said active electrode to thereby establish said auxiliary electrical discharge.

11. An instrument as in claim 10 where said second electrode is an electrically conductive tube disposed about and surrounding said active electrode.

12. An instrument as in claim 11 where said second electrode includes at least one inwardly directed, pointed projection extending from said tube whereby said auxiliary discharge occurs between said pointed projection and said active electrode.

13. An instrument as in claim 10 where said second electrode is an electrically conductive tube which is substantially collinearly disposed with respect to said active electrode so that said gas first flows by said tube to generate said electrostatic charge thereon and then it flows past said active electrode.

14. An instrument as in claim 13 where said active electrode is tubular.

15. An instrument as in claim 14 where the tubular second electrode includes at least one projection extending therefrom whereby said auxiliary discharge occurs between said pointed projection and said active electrode.

16. An instrument as in claim 10 where said discharge initiating means includes at least one pointed projection extending from at least said second electrode.

17. An instrument as in claim 10 where said discharge initiating means includes at least one pointed projection extending from at least said active electrode.

18. A method of using an instrument comprising a support;

an active electrode supported by said support and outwardly extending therefrom;

gas flow directing means adapted for the directing of gas past said electrode to provide gas adjacent the end of the electrode and extending outwardly therefrom;

discharge initiating means disposed adjacent to said electrode adapted for the initiation of a primary electrical discharge in said gas formed adjacent the end of the electrode, said discharge initiating means including said active electrode and a second electrode having a small gap therebetween, across which an auxiliary discharge initiates said electrical discharge in said gas formed adjacent the end of the active electrode;

said second electrode being electrically isolated from any source of biasing potential and being so disposed in the gas flow established by said gas flow directing means that said gas flow generates electrostatic charge on said second electrode, which is discharged through said gas to said active electrode to thereby establish said auxiliary electrical discharge;

said method comprising the steps of

directing inert gas past said active electrode and outwardly therefrom;

applying electrical energy to said active electrode; and

generating said auxiliary electrical discharge so that said auxiliary electrical discharge will initiate said primary electrical discharge from said active electrode; and

positioning said active electrode adjacent a body whereby said primary electrical discharge can be initiated without having to bring said active electrode into substantial contact with said body.

19. A method as in claim 18 where said body comprises living organic tissue and said electrical discharge effects coagulation of said tissue by fulguration.

20. A method as in claim 19 where said electrical energy is in form of periodic bursts of high frequency electrical current.

21. A method as in claim 18 where said body is metallic and said electrical discharge effects welding thereof.