Patent Number: 
Section: claims

1. An electron beam apparatus, comprising: a vacuum chamber;  a large-area cathode disposed in the vacuum chamber;  a first power supply connected to the cathode, wherein the first power supply is configured to apply a negative voltage to the cathode sufficient to cause the cathode to emit electrons toward a substrate disposed in the vacuum chamber;  an aluminum anode positioned between the large-area cathode and the substrate, the anode being positioned on an upper surface of an electrically isolated shelf that projects inwardly from an interior portion of the vacuum chamber; and  a second power supply connected to the anode, wherein the second power supply is configured to apply a voltage to the anode that is positive relative to the voltage applied to the cathode. 2. The apparatus of  claim 1 , wherein the interior portion of the vacuum chamber is one of bead blasted, roughened, anodized or darkened. claim 1 3. The apparatus of  claim 1 , wherein the interior portion of the vacuum chamber has an absorptivity of greater than about 0.5. claim 1 4. The apparatus of  claim 1 , wherein the first power supply is configured to apply a voltage ranging from about xe2x88x921000 volts to about xe2x88x9230,000 volts. claim 1 5. The apparatus of  claim 1 , wherein the second power supply is to apply a voltage ranging from about 0 volts to about xe2x88x92250 volts. claim 1 6. The apparatus of  claim 1 , wherein the large-area cathode emits the electrons when the large-area cathode is struck with positive ions. claim 1 7. The apparatus of  claim 1 , wherein the negative voltage applied to the large-area cathode is configured to attract positive ions to the large-area cathode; and wherein the electrons are emitted in response to the positive ions striking the large-area cathode. claim 1 8. The apparatus of  claim 1 , wherein an interior portion of the vacuum chamber has an absorptivity of greater than about 0.5; and wherein the anode is freely positioned on the shelf. claim 1 9. The apparatus of  claim 1 , wherein the shelf for laying the anode defines a space around a perimeter of the anode; and wherein an interior portion of the vacuum chamber is one of bead blasted, roughened, anodized or darkened. claim 1 10. The apparatus of  claim 1 , wherein the anode defines a plurality of holes disposed therethrough; and wherein an interior portion of the vacuum chamber is one of bead blasted, roughened, anodized or darkened. claim 1 11. The apparatus of  claim 1 , wherein the anode is placed on the shelf that defines a space around a perimeter of the anode and above the anode to allow the anode to expand and contract without bowing in response to varying temperatures during operation of the electron beam apparatus; and wherein an interior portion of the vacuum chamber is one of bead blasted, roughened, anodized or darkened. claim 1 12. The apparatus of  claim 11 , wherein the interior portion of the vacuum chamber has an absorptivity of greater than about 0.5. claim 11 13. The apparatus of  claim 1 , wherein the anode defines a plurality of holes disposed therethrough. claim 1 14. The apparatus of  claim 13 , wherein the plurality of holes have a diameter that gradually decreases from a center of the anode to an edge of the anode. claim 13 15. The apparatus of  claim 13 , wherein the plurality of holes have a diameter that gradually increases from a center of the anode to an edge of the anode. claim 13 16. The apparatus of  claim 1 , wherein the anode and shelf are configured to allow both vertical and horizontal expansion of the anode, while maintaining a substantially planar upper surface of the anode, under varying thermal conditions. claim 1 17. The apparatus of  claim 16 , wherein the shelf defines a space around a perimeter of the anode. claim 16 18. The apparatus of  claim 16 , wherein at least one of the vacuum chamber, the large-area cathode or the shelf is made from aluminum. claim 16 19. The apparatus of  claim 16 , wherein the shelf defines a space above the anode. claim 16 20. The apparatus of  claim 19 , wherein the shelf further defines a space around a perimeter of the anode. claim 19 21. The apparatus of  claim 20 , wherein each space allows the anode to expand and contract without bowing in response to varying temperatures during operation of the electron beam apparatus. claim 20 22. An electron beam apparatus, comprising: a vacuum chamber, wherein an interior portion of the vacuum chamber is one of bead blasted, roughened, anodized or darkened;  a large-area cathode disposed in the vacuum chamber;  a first power supply connected to the cathode, wherein the first power supply is configured to apply a negative voltage to the cathode sufficient to cause the cathode to emit electrons toward a substrate disposed in the vacuum chamber;  an anode freely positioned between the large-area cathode and the substrate on an inwardly projecting shelf; and  a second power supply connected to the anode, wherein the second power supply is configured to apply a voltage to the anode that is positive relative to the voltage applied to the cathode. 23. The apparatus of  claim 22 , wherein an interior portion of the vacuum chamber has an absorptivity of greater than about 0.5. claim 22 24. The apparatus of  claim 22 , wherein the first power supply is configured to apply a voltage ranging from about xe2x88x921000 volts to about xe2x88x9230,000 volts. claim 22 25. The apparatus of  claim 22 , wherein the second power supply is configured to apply a voltage ranging from about 0 volts to about xe2x88x92250 volts. claim 22 26. The apparatus of  claim 22 , wherein the anode defines a plurality of holes disposed therethrough. claim 22 27. The apparatus of  claim 26 , wherein the plurality of holes has a diameter that gradually decreases from a center of the anode to an edge of the anode. claim 26 28. The apparatus of  claim 26 , wherein the plurality of holes has a diameter that gradually increases from a center of the anode to an edge of the anode. claim 26 29. The apparatus of  claim 22 , wherein the shelf is electrically isolated from the anode and the vacuum chamber. claim 22 30. The apparatus of  claim 29 , wherein the shelf defines a space around a perimeter of the anode. claim 29 31. The apparatus of  claim 29 , wherein at least one of the vacuum chamber, the large-area cathode or the shelf is made from aluminum. claim 29 32. The apparatus of  claim 29 , wherein the shelf defines a space above the anode. claim 29 33. The apparatus of  claim 32 , wherein the shelf further defines a space around a perimeter of the anode. claim 32 34. The apparatus of  claim 33 , wherein each space allows the anode to expand and contract without bowing in response to varying temperatures during operation of the electron beam apparatus. claim 33 35. An electron beam apparatus, comprising: a vacuum chamber;  a large-area cathode disposed in the vacuum chamber;  a first power supply connected to the cathode, wherein the first power supply is configured to apply a negative voltage to the cathode sufficient to cause the cathode to emit electrons toward a substrate disposed in the vacuum chamber;  an anode placed between the large-area cathode and the substrate;  an electrically isolated shelf disposed in the vacuum chamber, wherein the shelf defines a surface on which the anode is placed is inwardly projecting and; and  a second power supply connected to the anode, wherein the second power supply is configured to apply a voltage to the anode that is positive relative to the voltage applied to the cathode. 36. The apparatus of  claim 35 , wherein the shelf defines a space around a perimeter of the anode. claim 35 37. The apparatus of  claim 35 , wherein at least one of the vacuum chamber, the large-area cathode or the shelf is made from aluminum. claim 35 38. The apparatus of  claim 35 , wherein an interior portion of the vacuum chamber is one of bead blasted, roughened, anodized or darkened. claim 35 39. The apparatus of  claim 35 , wherein an interior portion of the vacuum chamber has an absorptivity of greater than about 0.5. claim 35 40. The apparatus of  claim 35 , wherein the first power supply is configured to apply a voltage ranging from about xe2x88x921000 volts to about xe2x88x9230,000 volts. claim 35 41. The apparatus of  claim 35 , wherein the second power supply is configured to apply a voltage ranging from about 0 volts to about xe2x88x92250 volts. claim 35 42. The apparatus of  claim 35 , wherein the anode defines a plurality of holes disposed therethrough. claim 35 43. The apparatus of  claim 42 , wherein the plurality of holes has a diameter that gradually decreases from a center of the anode to an edge of the anode. claim 42 44. The apparatus of  claim 42 , wherein the plurality of holes has a diameter that gradually increases from a center of the anode to an edge of the anode. claim 42 45. The apparatus of  claim 35 , wherein the shelf defines a space above the anode. claim 35 46. The apparatus of  claim 45 , wherein the shelf further defines a space around a perimeter of the anode. claim 45 47. The apparatus of  claim 46 , wherein each space allows the anode to expand and contract in response to varying temperatures during operation of the electron beam apparatus. claim 46