Method and apparatus for plasma generation

1. A plasma source comprising: a body defining an input port, an output port, and at least one discharge section extending along a central longitudinal axis between the input port and the output port, the at least one discharge section including: a return electrode defining a first generally cylindrical interior volume having a first interior diameter disposed perpendicular to the central longitudinal axis; a supply plate comprising a supply electrode, the supply plate defining a second generally cylindrical interior volume having a second interior diameter disposed perpendicular to the central longitudinal axis; and at least one spacer defining a third generally cylindrical interior volume having a third interior diameter disposed perpendicular to the central longitudinal axis, the third interior diameter larger than the first and second interior diameters, such that a portion of the interior volume of the at least one spacer is laterally recessed relative to the return electrode and the supply electrode; wherein the at least one discharge section is formed from the at least one spacer arranged between the return electrode and the supply plate along the central longitudinal axis to define a ring-shaped discharge gap for generating a plasma therein, the discharge gap located in the recessed portion of the interior volume of the at least one spacer, and wherein the first, second and third interior volumes share the same central longitudinal axis in the at least one discharge section.

2. The plasma source of claim 1 , wherein the return electrode is electrically grounded.

3. The plasma source of claim 1 , wherein the supply plate further comprises at least one dielectric member laterally surrounding the supply electrode.

4. The plasma source of claim 3 , wherein the at least one dielectric member of the supply plate is a ring-shaped barrier dielectric member configured to laterally surround the supply electrode that is ring-shaped.

5. The plasma source of claim 1 , wherein the at least one discharge section further comprises a ring-shaped isolation dielectric member positioned adjacent to the supply plate along the central longitudinal axis.

6. The plasma source of claim 1 , wherein the first interior diameter of the return electrode and the second interior diameter of the supply plate are substantially the same.

7. The plasma source of claim 1 , wherein the discharge gap is bounded longitudinally between a lateral surface of the return electrode and a lateral surface of the supply plate and bounded laterally by the at least one spacer.

8. The plasma source of claim 7 , wherein a discharge current is formed within the discharge gap between the lateral surface of the return electrode and the lateral surface of the supply plate, the discharge current being adapted to flow parallel to the central longitudinal axis and perpendicular to the lateral surfaces.

9. The plasma source of claim 8 , wherein a current density of the discharge current is substantially uniform around the central longitudinal axis.

10. The plasma source of claim 1 , wherein the at least one spacer of the discharge section comprises a plurality of spacers joined along the central longitudinal axis.

11. The plasma source of claim 1 , wherein the body of the plasma source comprises a plurality of discharge sections arranged along the central longitudinal axis.

12. The plasma source of claim 11 , wherein the plurality of discharge sections form a plurality of discontinuous discharge gaps along the central longitudinal axis for generating respective ones of plasmas.

13. The plasma source of claim 12 , wherein the plurality of discharge gaps are substantially uniform.

14. The plasma source of claim 1 , wherein at least one of the return electrode, the supply plate or the at least one spacer is formed by one of co-firing or bonding.

15. The plasma source of claim 1 , wherein the at least one spacer is made from an electrically non-conductive material.

16. A method of manufacturing a plasma source, the method comprising: assembling at least one discharge section comprising: providing a return electrode defining a first generally cylindrical interior volume having a first interior diameter disposed perpendicular to a central longitudinal axis; providing a supply plate comprising a supply electrode, the supply plate defining a second generally cylindrical interior volume having a second interior diameter disposed perpendicular to the central longitudinal axis; providing at least one spacer that defines a third generally cylindrical interior volume having a third interior diameter disposed perpendicular to the central longitudinal axis, the third interior diameter larger than the first and second interior diameters, such that a portion of the interior volume of the at least one spacer is laterally recessed relative to the return electrode and the supply electrode; and locating the spacer between the return electrode and the supply plate along the central longitudinal axis to define a ring-shaped discharge gap for generating a plasma therein, the discharge gap located in the recessed portion of the interior volume of the spacer, wherein the first, second and third interior volumes share the same central longitudinal axis in the at least one discharge section; and forming a body comprising an input port, an output port, and the at least one discharge section extending along the central longitudinal axis between the input port and the output port.

17. The method of claim 16 , further comprising electrically grounding the return electrode.

18. The method of claim 16 , wherein the supply plate further comprises at least one dielectric member laterally surrounding the supply electrode.

19. The method of claim 16 , wherein assembling the at least one discharge section further comprises providing a ring-shaped isolation dielectric member and positioning the isolation dielectric member adjacent to the supply plate along the central longitudinal axis.

20. The method of claim 16 , wherein the discharge gap is bounded longitudinally between a lateral surface of the return electrode and a lateral surface of the supply plate and bounded laterally by the spacer.

21. The method of claim 20 , further comprising:

generating a discharge current within the discharge gap between the lateral surface of the return electrode and the lateral surface of the supply plate; and

flowing the discharge current generally parallel to the central longitudinal axis and perpendicular to the lateral surfaces.

22. The method of claim 21 , wherein a density of the discharge current is substantially uniform around the central longitudinal axis.

23. The method of claim 16 , further comprising:

assembling a plurality of discharge sections;

and arranging the plurality of discharge sections along the central longitudinal axis between the input port and the output port to form the body of the plasma source.

24. The method of claim 23 , further comprising forming a plurality of discontinuous discharge gaps by the plurality of discharge sections along the central longitudinal axis for generating respective ones of plasmas.

25. The method of claim 16 , further comprising forming at least one of the return electrode, the supply plate or the at least one spacer by one of co-firing or bonding to assemble the at least one discharge section.

26. The method of claim 16 , wherein the spacer is made from an electrically non-conductive material.