Combined Thermal and Voltage Transfer System for an X-ray Source

Abstract

A thermal control and electrical connection means for an electronic radiation source that provides a cooling and electrical connection to an electronic radiation source in high-temperature environment is provided, including at least a means for physically dislocating a positive high-voltage generator from the anode/target of the x-ray source; a means for conveying coolant fluids to a target anode along a coaxially formed connector; and a means for removing heat from the target anode along a coaxially-formed connector. A method of removing thermal energy from the target of an electronic radiation source is also provided, including at least introducing coolant fluids onto the target; removing coolant fluids from the target; and relocating the coolant fluids to another part of the tool for disposal within the wellbore.

Claims

1. A thermal control and electrical connection tool for an electronic radiation source that provides a cooling and electrical connection to an electronic radiation source in high-temperature environment, the tool comprising: a means for physically dislocating a positive high-voltage generator from the anode/target of the x-ray source; a means for conveying coolant fluids to a target anode along a coaxially formed connector; and a means for removing heat from the target anode along a coaxially-formed connector.

2. The tool of claim 1, where the coaxial structure bypasses annular ground-potential volumes located axially adjacent to the x-ray anode/target such that the volume is used for radiation detectors used for geo-physical measurements.

3. The tool of claim 1, where the electronic radiation source is an x-ray source.

4. The tool of claim 1, where the electronic radiation source is a pulsed neutron source.

5. The tool of claim 1, where the means is disposed within a wireline tool.

6. The tool of claim 1, where the means is disposed within a LWD tool.

7. A method of removing thermal energy from the target of an electronic radiation source, the method comprising: introducing coolant fluids onto the target, removing coolant fluids from the target; and relocating of coolant fluids to another part of the tool for disposal within the wellbore.

8. The method of claim 7, further comprising bypassing annular ground-potential volumes located axially adjacent to the x-ray target anode such that the volume is used for radiation detectors used for geo-physical measurements.

9. The method of claim 7, further comprising using an x-ray source as the electronic radiation source.

10. The method of claim 7, further comprising using a pulsed neutron source as the electronic radiation source.

11. The method of claim 7, further comprising using said method within a wireline tool.

12. The method of claim 7, further comprising using said method within a LWD tool.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] FIG. 1 illustrates an example narrow format bipolar configured x-ray tube wherein the target anode is simultaneously cooled and electrically connected via an electrically conductive and narrow format bi-direction fluid conduit.

[0037] FIG. 2 illustrates an example method to connect an electrically conductive and narrow format bi-direction fluid conduit to a target anode, thereby permitting the removal of thermal energy from the target.

BRIEF DESCRIPTION OF SEVERAL EXAMPLE EMBODIMENTS

[0038] The methods and means described herein enable the efficient and stable use of ultra-high voltage x-ray tubes and electronic radiation sources within the high-temperature environment of a borehole. A thermal control and electrical interconnect mechanism for an electronic radiation source in high-temperature environments is provided, the tool including at least an electronic radiation source where in the target is cooled by a structure that also conducts the high electrical potentials required of a bipolar electronic source configuration.

[0039] With reference now to the attached Figures, FIG. 1 illustrates a bipolar configured x-ray tube [102] with a high-voltage connector [101], that is further connected to a filament or cold-cathode device [103] contained within the vacuum enclosure of the tube [104]. Electrons from the filament are accelerated between the cathode [103] and anode [105], and impinge upon a target material [105]. Heat generated within the target [105] is removed by fluid circulation [111, 112] along the same conduit [113] that is employed as a high voltage connector to the target anode [105], via a high voltage connector [110]. The non-vacuum regions surrounding the high voltage elements, may be filled with a gaseous insulator [106]. A source beam collimator [107] may be placed around the target anode [105] to create specific beam paths [108] for the produced x-rays. One benefit of the compact and narrow integrated coolant and electrical connection conduit is that is provides for a substantial annular volume around the structure, which could be used for detector placement [109]. The anti-coronal structure [202] can also be used as a collimating shield to define a conical beam path [201] from x-rays emanating from the target [203]. The anti-coronal structure can comprise a plurality of different materials, thereby permitting a continuous surface while providing low attenuation windows [205] for the x-ray beam path. The end of the coolant conduit [204] once integrated with the target structure [207] permits lower temperature coolant [206, 111] to be circulated over the target structure [207], and removing heat to another part of the tool for disposal into the well bore via a higher-temperature return conduit [112].

[0040] In one embodiment, a bipolar x-ray tube consists a coaxial electrical conductor that connects the end of a positive high-voltage generator to the anode/target of an x-ray tube in a bipolar configuration. The coaxial electrical conductor also serves as a fluid conveyance conduit providing coolant fluid to the anode and removing said coolant fluid from the target/anode along the annulus of the coaxial connector. The coaxial connector is formed in such a way as to provide annular space within the housing of the downhole tool for detector systems associated with the downhole measurement. The coolant is injected and retrieved from the coaxial conductor system through a network of conduits formed to reduce the electrical field stress on the coolant fluid as the fluid path traverses from a high-electrical-field region to a low-electrical-field region.

[0041] In a further embodiment, the coolant is introduced onto or into the anode/target of the x-ray tube, and returns along the annulus of the coaxially-formed connector, thereby carrying excess thermal energy away from the hot source/target anode, while also providing a means of conveying a high-electrical potential to the anode/target of the x-ray source.

[0042] In a further embodiment, the coaxial structure bypasses annular ground-potential volumes located axially adjacent to the x-ray anode/target, such that the volume may be used for photo detectors used for geo-physical measurements, such as in x-ray cement evaluation, x-ray imaging, or litho-density measurements.

[0043] In a further embodiment, the arrangement would be housed within a wireline tool and conveyed into a borehole by means of wireline conveyance.

[0044] In a further embodiment, the arrangement is housed within a drill collar and conveyed into a borehole by means of LWD conveyance.

[0045] The foregoing specification is provided only for illustrative purposes, and is not intended to describe all possible aspects of the present invention. While the invention has herein been shown and described in detail with respect to several exemplary embodiments, those of ordinary skill in the art will appreciate that minor changes to the description, and various other modifications, omissions and additions may also be made without departing from the spirit or scope thereof.