System, method and apparatus for generating plasma

• US 8,575,843 B2
• Filed: 05/29/2009
• Issued: 11/05/2013
• Est. Priority Date: 05/30/2008
• Status: Active Grant

• Current Assignee: Colorado State University Research Foundation (Colorado State University System)
• Original Assignee: Colorado State University Research Foundation (Colorado State University System)
• Inventors: Moore, Cameron A., Scott, Douglas A., Collins, George J.
• Primary Examiner(s): Le, Tung X
• Application Number:
  US12/995,114
• Publication Number:
  US 20110140607A1
• Time in Patent Office: 1,621 Days
• Field of Search: 31511121-11191
• US Class Current: 315/111.21
• CPC Class Codes: A61B 18/042 using additional gas becoming plasma
• CPC Class Codes: H05H 1/30 using applied electromagnetic fields, e.g. high frequency or microwave energy H05H1/28 takes precedence
• CPC Class Codes: H05H 1/36 Circuit arrangements H05H1/38, H05H1/40 take precedence

Abstract

A plasma generating system, related method and device are disclosed. The plasma generation system includes a plasma generation device, a source of ionizable gas and a driver network. The plasma generation device includes a housing, an electrode, and a resonant circuit. The housing includes a passage defined therein and directs a flow of ionizable gas therethrough. The electrode is coupled to the ionizable gas flowing through the passage of the housing. The resonant circuit includes a capacitor and an inductor connected together in series. The resonant circuit has a resonance frequency and is coupled to the electrode. The resonant circuit receives an AC signal. The driver network provides the AC signal such that the AC signal has a frequency and excites the ionizable gas flowing through the passage of the housing to a plasma.

Claims

1. A plasma-generating device, comprising:

a housing including a passage defined therein configured to direct a flow of an ionizable gas therethrough;

an electrode in communication with the ionizable gas flowing through the passage of the housing; and

a resonant circuit including a capacitor and an inductor connected together in series, the resonant circuit having a resonance frequency and electrically coupled to the electrode; and

a driver network configured to generate an AC signal having an excitation frequency substantially matching the resonance frequency of the resonant circuit, wherein the driver network provides the AC signal to the resonant circuit to excite the ionizable gas flowing through the passage of the housing to a plasma.

2. The device according to claim 1, further including an insulating tube defining the passage.

3. The device according to claim 2, wherein the electrode is disposed in proximity to the insulating tube.

4. The device according to claim 1, wherein the housing is in fluid communication with a source of the ionizable gas.

5. The device according to claim 4. wherein the electrode is disposed partially upstream adjacent the passage.

6. The device according to claim 1, further including a second electrode coupled to a ground and in communication with the plasma.

7. The device according to claim 6, wherein the housing further includes a fluid connection configured to fluidly connect to a source of ionizable gas to receive the ionizable gas, wherein the second electrode is positioned at an opposite end of a fluid connection.

8. The device according to claim 1, wherein the inductor is formed about the passage within the housing.

9. The device according to claim 1, wherein the electrode has a capacitance connected in parallel to the capacitor.

10. The device according to claim 1, wherein the capacitor and the inductor are connected together in series between the AC signal and a ground.

11. The device according to claim 1, wherein the capacitor has a capacitance value and the inductor has an inductance value, wherein a ratio of the inductance value over the capacitance value is from about 500 square-ohms to about 100,000 square-ohms.

12. The device according to claim 1, wherein at least one of the capacitor and the inductance is adjustable in magnitude.

13. The device according to claim 1, wherein the resonant circuit further includes a resistor electrically coupled to one of the capacitor and the inductor.

14. The device according to claim 13, wherein the resistance of the resistor is about two to about twenty times an equivalent series resistance of the capacitor and the inductor.

15. The device according to claim 1, further including an ignition electrode extending within an end of the housing adapted to assist the ignition of the ionizable gas.

16. The device according to claim 15, further including:

an ignition circuit coupled to the ignition electrode, the ignition circuit adapted to selectively assist in the ignition of the ionizable gas.

17. The device according to claim 16, further including a sensor component adapted to sense a current through the plasma, wherein the ignition circuit assists in the ignition of the ionizable gas when the sensor senses that the current through the plasma is about zero thereby indicating that the resonant circuit is not generating the plasma.

18. The device according to claim 15, further including:

a switch electrically coupled to a driver network providing the AC signal and the ignition electrode, and configured to connect and disconnect the ignition electrode to the driver network.

19. The device according of claim 1, wherein the resonant circuit is electrically coupled to the electrode via a conductive member to communicate electrical energy to the ionizable gas.

20. The device according to claim 1, wherein the resonant circuit is electrically coupled to the electrode via a coaxial cable.

21. The device according to claim 1, further including an electrosurgical electrode adapted to electrically couple electrosurgical energy to the plasma.

22. The device according to claim 1, further comprising:

an impedance matching network electrically coupled between the resonant circuit and a driver network providing the AC signal, the impedance matching network configured to approximately match an internal impedance of the driver network to an effective impedance of at least one of the resonant circuit when exciting the ionizable gas to the plasma and the resonant circuit when not exciting the ionizable gas to the plasma.

23. A plasma generating system, comprising:

a plasma generation device, including;

a housing including a passage defined therein configured to direct a flow of an ionizable gas therethrough;

an electrode in communication with the ionizable gas flowing through the passage of the housing; and

a resonant circuit including a capacitor and an inductor connected together in series, the resonant circuit having a resonance frequency and electrically coupled to the electrode;

a source of ionizable gas in fluid communication with the housing; and

a driver network configured to generate an AC signal having an excitation frequency substantially matching the resonance frequency of the resonant circuit, wherein the driver network provides the AC signal to excite the ionizable gas flowing through the passage of the housing to a plasma.

24. The system according to claim 23, the system further including an impedance matching network electrically coupled between the resonant circuit and the driver network providing the AC signal, the impedance matching network configured to approximately match an internal impedance of the driver network to an effective impedance of at least one of the resonant circuit when exciting the ionizable gas to the plasma and the resonant circuit when not exciting the ionizable gas to the plasma.

25. The system according to claim 23, wherein the circuit further includes a resistor electrically coupled in series with the driver network, wherein the resistor is chosen to decrease a Q and increase a bandwidth of the resonant circuit.

26. The system according to claim 23, wherein the driver network is configured to provide the frequency of the AC signal near to the resonance frequency of the resonant circuit.

27. The system according to claim 26, wherein the driver network provides the frequency of the AC signal to approximately match an internal impedance of the driver network to a predetermined impedance.

28. The system according to claim 27, wherein the predetermined impedance is an effective impedance of the resonant circuit while the resonant circuit generates the plasma.

29. The system according to claim 23, wherein the driver network provides the frequency of the AC signal to maintain a predetermined efficiency of the system.

30. The system according to claim 23, wherein the driver network provides the frequency of the AC signal to maintain a predetermined power dissipation within the plasma.

31. The system according to claim 23, wherein the driver network provides the frequency of the AC signal to maintain a power dissipation within the driver network to be about equal to a power dissipation within the resonant circuit when one of during the generation of the plasma and during no generation of the plasma.

32. The system according to claim 23, wherein the driver network provides the frequency of the AC signal within a predetermined bandwidth.

33. The system according to claim 32, wherein the bandwidth is approximately twice a frequency difference between the resonance frequency of the resonant circuit and another frequency, wherein the another frequency is defined by a frequency such that an internal impedance of the driver network is about matched to an effective impedance of the resonant circuit.

34. The system according to claim 23, wherein the driver circuit is configure to provide the AC signal to excite the ionizable gas to the plasma having an ionization greater than about 1*10⁻

7.

35. The system according to claim 23, wherein the driver circuit is configured to provide the AC signal to excite the ionizable gas to the plasma having a rotational temperature lower than about 100 degrees Celsius.

36. The system according to claim 23, wherein the driver circuit is configured to provide the AC signal to excite the ionizable gas to the plasma having a rotational temperature lower than about 50 degrees Celsius.

37. The system according to claim 23, wherein the driver circuit is configured to provide the AC signal to excite the ionizable gas to the plasma such that the rotational temperature is substantially lower than the vibration temperature when the plasma is substantially within the passage.

38. The system according to claim 23, wherein the resonant circuit has a Q value sufficient to maintain plasma ignition while dissipating at least one of about I watt and about 2 watts within the resonant circuit and the plasma.

39. The system according to claim 23, wherein the driver circuit provides the AC signal such that the AC signal dissipates from about 10'"'"'s of watts per cubic-centimeter in the plasma to about 1,000'"'"'s of watts per cubic-centimeter in the plasma.

40. The system according to claim 23, further including:

a gas cooling device in fluid communication with and disposed between the source of ionizable gas and the passage of the housing, the gas cooling device cools the ionizable gas flowing into the passage of the housing.

41. A method of generating plasma, comprising:

providing a fluid path for directing a flow of an ionizable gas;

providing a resonant circuit including a capacitor and an inductor connected together in series, the resonant circuit having a resonance frequency, wherein the resonant circuit is coupled to a driver network configured to supply an AC signal thereto;

determining an excitation frequency of the AC signal to substantially match the resonance frequency of the resonant circuit; and

applying the AC signal to the resonant circuit thereby exciting the ionizable gas to form a plasma.

42. The method according to claim 41, further including:

determining a phase difference between a phase of a current flowing through the plasma and a phase of a voltage across the plasma; and

adjusting the frequency of the AC signal as a function the phase difference.

43. The method according to claim 41, wherein the frequency of the AC signal is adjusted only as a function of the phase difference.

44. The method according to claim 41, further including adjusting the power of the AC signal while maintaining a predetermined phase difference.

45. The method according to claim 41, further including determining an impedance mismatch.

46. The method according to claim 45, further including adjusting the frequency of the AC signal to compensate for the impedance mismatch.

47. The method according to claim 45, further including adjusting an internal impedance of a driver network providing the AC signal to compensate for the impedance mismatch.

48. The method according to claim 41, further including determining a phase difference between a phase of a current flowing through the plasma and a phase of a voltage across the plasma.

49. The method according to claim 48, further including:

comparing the phase difference to a predetermined phase difference; and

adjusting an internal impedance of a driver network providing the AC signal to compensate for the comparison of the phase difference and the predetermined phase difference being greater than a predetermined threshold.

50. The method according to claim 48, further including:

comparing the phase difference to a predetermined phase difference;

adjusting the frequency of the AC signal to compensate for the comparison of the phase difference to the predetermined phase difference; and

maintaining the predetermined phase difference