Anode terminal for reducing field enhancement

Abstract

An anode terminal is provided for use high voltage applications that also serves as a shield, and which reduces the overall size of the anode terminal and an enclosure containing the anode terminal. The anode terminal includes a toroid and the maximum radius of curvature that is required to provide an optimal field enhancement reduction is reserved for the section of the toroid that is closest to ground, including the walls of the enclosure. The toroid of the anode terminal has variable radii of curvature along its outer surface and is asymmetrical.

Claims

1. An apparatus comprising: an enclosure containing: a cable well having a ground end affixed to a wall of the enclosure and a high voltage end opposing the ground end; and an anode terminal affixed to the high voltage end of the cable well, comprising a toroid configured to reduce high voltage arcing, wherein the toroid of the anode terminal comprises an outer surface having a plurality of radii of curvature, and wherein the largest radius of curvature of the outer surface of the toroid of the anode terminal is along a section around the outer surface of the toroid having one or more points on the outer surface that are closest to the enclosure.

2. The apparatus according to claim 1, wherein the anode terminal further comprises a disc in a hole in a center of the toroid configured to connect the anode terminal to the high voltage end of the cable well.

3. The apparatus according to claim 2, wherein the toroid of the anode terminal is substantially perpendicular to the cable well.

4. The apparatus according to claim 2, wherein the anode terminal is asymmetrical about a plane perpendicular to the cable well and parallel to the disc.

5. The apparatus according to claim 2, wherein the plurality of radii of curvature of the outer surface of the toroid of the anode terminal include a plurality of intermediate radii of curvature less than the largest radius of curvature.

6. The apparatus according to claim 2, wherein corners of the toroid facing the center of the toroid are rounded.

7. The apparatus according to claim 2, further comprising an insulating medium in the enclosure surrounding the cable well and the anode terminal.

8. The apparatus according to claim 2, wherein the anode terminal, including the toroid and the disc, are made from aluminum.

9. The apparatus according to claim 2, wherein the anode terminal, including the toroid and the disc, are made from brass.

10. The apparatus according to claim 2, wherein the largest radius of curvature of the outer surface of the toroid of the anode terminal is approximately 3 inches and the distance between the enclosure and the one or more points along the section around the outer surface of toroid having the largest radius of curvature is approximately 4.5 inches.

11. The apparatus according to claim 2, wherein the distance between the enclosure and the one or more points along the section around the outer surface of toroid having the largest radius of curvature is approximately 1.5 times greater than the largest radius of curvature of the outer surface of the toroid of the anode terminal.

12. The apparatus according to claim 2, wherein the disc in the center of the toroid is offset towards a ground side of the anode terminal.

13. An apparatus comprising: an anode terminal comprising a toroid configured to reduce high voltage arcing, wherein the toroid of the anode terminal comprises an outer surface having a plurality of radii of curvature, and wherein the largest radius of curvature of the outer surface of the toroid of the anode terminal is along a section around the outer surface of the toroid having one or more points on the outer surface that are configured to be closest to a wall of an enclosure housing the anode terminal.

14. The apparatus according to claim 13, wherein the anode terminal further comprises a disc in a hole in a center of the toroid configured to connect the anode terminal to a high voltage end of a cable well.

15. The apparatus according to claim 14, wherein the anode terminal is asymmetrical about a plane parallel to the disc.

16. The apparatus according to claim 14, wherein the plurality of radii of curvature of the outer surface of the toroid of the anode terminal include a plurality of intermediate radii of curvature less than the largest radius of curvature.

17. The apparatus according to claim 14, wherein corners of the toroid facing the center of the toroid are rounded.

18. The apparatus according to claim 14, wherein the anode terminal, including the toroid and the disc are made from aluminum or brass.

19. The apparatus according to claim 14, wherein the largest radius of curvature of the outer surface of the toroid of the anode terminal is approximately 3 inches.

20. The apparatus according to claim 14, wherein the disc in the center of the toroid is offset towards a ground side of the anode terminal.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0032] FIG. 1 shows a cross-sectional view of an embodiment of a high-voltage power supply enclosure according to the prior art.

[0033] FIG. 2 shows a cross-sectional view of a further embodiment of a high-voltage power supply enclosure.

[0034] FIG. 3 shows a cross-sectional view of a first embodiment of the invention including a high voltage anode terminal in an enclosure, in accordance with the present invention.

[0035] FIG. 4 shows a cross-sectional view of a first embodiment of a high voltage anode terminal in accordance with the present invention.

[0036] FIG. 5A shows a cross-sectional view of a second embodiment of a high voltage anode terminal in accordance with the present invention.

[0037] FIG. 5B shows a further cross-sectional view of a second embodiment of a high voltage anode terminal in accordance with the present invention.

DETAILED DESCRIPTION OF THE FIGURES

[0038] The present invention will now be described with reference made to FIGS. 2-5B. A first attempt at making the terminal 30 of FIG. 1 more space efficient is shown in the HVPS of FIG. 2. In the embodiment of FIG. 2, a cable well 20 having a ground or low voltage end 21 and a high voltage end 22, similar to the cable well 20 of FIG. 1 is provided inside a tank 10b. A high voltage anode terminal 40 is attached to the high voltage end 22 of the cable well 20, and the high voltage terminal 40 includes a toroid 41 with a center disc 42. However, in contrast to the donut-shaped toroid 31 of the high voltage anode terminal 30 of FIG. 1, the cross-sectional shape of the toroid 41 is made a half circle instead of a full circle, as shown in FIG. 2. This change in shape reduces the required overall space by 3 inches on each side of the toroid 41, in comparison to the toroid 31 of FIG. 1. The semi-circular cross-section of toroid 41 has a radius D.sub.6 of 3 inches and the distance D.sub.2 from the toroid 41 to ground is 4.5 inches. Therefore, the preferred ratio of distance D.sub.2 to ground to the radius of curvature of the terminal 40 is maintained. With the diameter of the disc 42 and the cable well diameter 20 being 3 inches, the outer diameter D.sub.7 of the high voltage terminal 40 is reduced to 9 inches and the tank width D.sub.8 is reduced to 18 inches.

[0039] However, there is a serious flaw in this arrangement because the half circle has sharp corners resulting in edges that are worse than the original small terminals. Furthermore, the side of the terminal 40 facing ground encroaches 3 inches along the length L.sub.1 of the cable well 20, reducing its effective insulating length to a very inadequate 4 inches.

[0040] The present invention avoids these problems by providing a high voltage anode terminal comprising multiple radii of curvature along the outer surface of the toroid of the anode terminal. Smaller radii of curvature are introduced into the cross-section of the toroid, reserving the largest radius of curvature for only the outside surface facing ground. The corners of the intermediate step above are rounded on the ground side and 0.25 inches on the high voltage side.

[0041] An example of an embodiment of the present invention is shown in FIGS. 3 and 4.

[0042] In accordance with an embodiment of the present invention, a tank 10c is provided, which is filled with an insulating medium 15 and includes a cable well 20 having a ground end 21 and a high voltage end 22. A high voltage anode terminal 50 is provided, comprising a toroid 51 surrounding a center disc 52. The high voltage anode terminal, including the toroid 51 and center disc 52 may be made from materials such as aluminum or brass. The high voltage end 22 of the cable well 20 can be attached to the center disc 52 by inserting a plurality of screws through openings in the cable well 20 and disc 52, as previously described in the embodiment of FIG. 1. In an illustrative embodiment, the cable well 20 may have a diameter D.sub.1 of 3 inches and a length L.sub.1 of 7 inches, consistent with previously described embodiments. However, it is noted that the dimensions of the cable well 20 can vary in other embodiments, and the cable well 20 diameter D.sub.1 and length L.sub.1 are not limited to 3 inches and 7 inches, respectively.

[0043] In contrast to the terminals 30, 40 of FIGS. 1 and 2, the outer surface of the toroid 51 of the terminal 50 does not have a constant radius of curvature. The terminal 50 has multiple radii of curvature, which vary along the outer surface of the toroid 51. The section around the outer surface of the toroid 51 that is closest to ground (i.e., closest to the walls of the tank 10c) has the largest radius of curvature R.sub.1. In the embodiment shown in the Figures, the largest radius of curvature R.sub.1 is 3 inches. The distance D.sub.2 to ground between the toroid 51 at the points having this radius of curvature R.sub.1 is 4.5 inches, and as a result, a 1.5:1 ratio of distance D.sub.2 to ground to terminal radius of curvature R.sub.1 is provided. In embodiments where the tank 10c is cylindrical in shape having a circular cross-section, the distance D.sub.2 to ground from the toroid 51 may extend along a section around the entire perimeter of the toroid, and in embodiments where the tank 10c is a cube or box having a square, rectangular or other polygonal cross-section, the toroid 51 may be closest to ground at discrete points along a section around the perimeter of the toroid 51.

[0044] The remainder of the outer surface of the toroid 51 does not require a radius of curvature R.sub.1 that is approximately two-thirds the distance D.sub.2 to ground. To smooth out between the largest radius of curvature R.sub.1 and the smaller radii of curvature around the outer surface of the toroid 51, intermediate radii of curvature are introduced. For example, in accordance with one embodiment of the invention, an intermediate radius of curvature R.sub.2 of 1.25 inches can be provided on the ground side of the toroid 51 and an intermediate radius of curvature R.sub.3 of 1 inch can be provided on the high voltage side of the toroid 51.

[0045] The corners of the intermediate step above the maximum radius of curvature R.sub.1 and intermediate radii of curvature R.sub.2, R.sub.3 can be rounded. In the embodiment shown in the Figures, the corners of the toroid 51 can be rounded to a radius of curvature R.sub.4 of approximately 0.44 inches on the ground side and a radius of curvature R.sub.5 of 0.25 inches on the high voltage side.

[0046] In the embodiment shown in the Figures and described above, the distance D.sub.9 across the outer portion of the toroid 51 is approximately 1.5 inches. The resultant toroid 51 has an outer diameter D.sub.10 of approximately 6 inches, allowing the width D.sub.11 of the tank 10c to be reduced to 15 inches.

[0047] The center disc 52 plugging the center hole inside the toroid 51 can be offset slightly toward the ground side, resulting in a virtually negligible reduction in the well length L.sub.1. In the embodiment of the terminal 50 shown in FIG. 4, the overall height H.sub.1 of the terminal can be approximately 2.7 inches. With the disc 52 being slightly offset towards ground, the height H.sub.2 of the ground side section of the terminal 50 can be approximately 0.75 inches, the height H.sub.3 of the central portion of the terminal 50 including the center disc 52 can be approximately 0.55 inches, and the height H.sub.4 of the high voltage side section of the terminal 50 can be approximately 1.4 inches. Additionally, the distance D.sub.11 across the center of toroid 51 above the disc 52 is sufficient to receive the cable well 20, and may provide for additional space between the cable well 20 and toroid 51. This distance D.sub.11 may be, for example, 3.17 inches where the diameter D.sub.1 of the cable well 20 is 3 inches. In certain embodiments of the invention, the distance D.sub.12 across the center of the toroid 51 below the disc 52 may be the same as or greater than the distance D.sub.11 across the center of toroid 51 above the disc 52. For example, in the embodiment shown in FIG. 4, this distance D.sub.12 can be 3.25 inches. The cavity in the center of the toroid 51 on the side of the disc 52 that is not attached to the cable well 20 may provide further connections (not shown). This may include, for example, a connection to a high voltage stack.

[0048] This variable radius terminal 50, in contrast to a traditional constant radius terminal 30, makes use of larger radii of curvature only where needed and smaller radii of curvature where the distances are greater or the voltages are smaller. The terminal 50 is therefore much smaller and therefore less expensive. In comparison to the tank 10a of FIG. 1, the reduced overall size of the terminal 50 of the present invention allows the volume of the tank 10c to be potentially reduced by a ratio 2.56:1 (24.sup.2/15.sup.2 or 576/225). As a result, the size and cost of the tank 10c is reduced, and the required amount of insulating medium 15 to fill the tank 10c is also reduced.

[0049] The high voltage anode terminal 50 can be used in a variety of applications requiring a high voltage without departing from the scope of the invention, including for example in high voltage power supplies, voltage dividers, X-ray tubes and other scientific instruments.

[0050] Alternative embodiments of the high voltage anode terminal of the present invention may be provided without departing from the scope of the invention. One example of such an alternative embodiment is shown in FIGS. 5A and 5B, which illustrate a high-voltage anode terminal 60. The high-voltage anode terminal 60 does not include a central disc, as in the previous embodiments. The high-voltage anode terminal 60 may be configured for use with a higher voltage cable well, such as 225 kV, and in an enclosure having dimensions that differ from the enclosures of FIGS. 1-4. In one exemplary embodiment of the high-voltage terminal 60 shown in FIGS. 5A-5B, the possible dimensions of the high-voltage terminal 60 may be, approximately:

TABLE-US-00001 TABLE 1 D.sub.14 4.67 inches D.sub.15 5.67 inches D.sub.16  0.5 inches H.sub.5 3.45 inches H.sub.6 0.45 inches H.sub.7  2.0 inches H.sub.8 0.64 inches H.sub.9 0.37 inches R.sub.6  2.5 inches R.sub.7 1.25 inches R.sub.8  2.0 inches R.sub.9 0.313 inches 

[0051] It should be understood that, unless stated otherwise herein, any of the features, characteristics, alternatives or modifications described regarding a particular embodiment herein may also be applied, used, or incorporated with any other embodiment described herein. Additionally, the drawings herein may not be drawn to scale in whole or in part. The various dimensions of the elements of the invention that are referenced herein may be modified without departing from the scope of the invention.

[0052] Although the invention has been described and illustrated with respect to exemplary embodiments thereof, the foregoing and various other additions and omissions may be made therein and thereto without departing from the spirit and scope of the present invention.