Multilayer X-ray source target with high thermal conductivity
View Patent ↗In one embodiment, an X-ray source target is provided that includes two or more layers of X-ray generating material at different depths within a source target for an electron beam. In one such embodiment the X-ray generating material in each layer does not extend fully across an underlying substrate surface.
1. An X-ray source target, comprising:
a structure configured to generate X-rays when impacted by an electron beam, the structure comprising:
two or more X-ray generating layers each comprising X-ray generating material extending less than the full extent of the surface of the structure; and
at least one thermally-conductive layer between each pair of X-ray generating layers; and
a thermally conductive top-layer deposited over a first X-ray generating layer relative to a cathode-facing surface of the structure, wherein the top layer comprises a thermally conductive material having a thermal conductivity in a range from about 250 W/m-K to about 1700 W/m-K.
2. The X-ray source target of claim 1 , wherein each X-ray generating layer comprises a thermally conductive material where there is no X-ray generating material.
3. The X-ray source target of claim 1 , wherein the thermally conductive material of the top-layer comprises highly ordered pyrolytic graphite (HOPG), diamond, beryllium oxide, silicon carbide, copper-molybdenum, oxygen-free high thermal conductivity copper (OFHC), silver-diamond, or any combination thereof.
4. The X-ray source target of claim 1 , further comprising a thermally-conductive substrate on which a bottommost X-ray generating layer is formed.
5. The X-ray source target of claim 1 , wherein the X-ray generating material within at least one X-ray generating layer is ring-shaped.
6. The X-ray source target of claim 1 , wherein the X-ray generating material within at least one X-ray generating layer is circular.
7. The X-ray source target of claim 1 , further comprising one or more trenches extending at least through the two or more X-ray generating layers.
8. The X-ray source target of claim 1 , wherein the structure comprises a stationary anode structure.
9. The X-ray source target of claim 1 , wherein the cross-sectional extent of the X-ray generating material within each X-ray generating layer is sized to correspond to the impact area of an electron beam during operation.
10. An X-ray source target, comprising:
a structure configured to generate X-rays when impacted by an electron beam, the structure comprising:
a substrate; and
a multi-layer structure formed on the substrate and only partially covering a cathode-facing surface of the substrate, the multi-layer structure comprising:
alternating layers of X-ray generating material and thermally-conductive material; and
a thermally conductive top-layer deposited over a first X-ray generating layer relative to the cathode-facing surface of the structure, wherein the top layer comprises a thermally conductive material having a thermal conductivity in a range from about 250 W/m-K to about 1700 W/m-K.
11. The X-ray source target of claim 10 , wherein the multi-layer structure comprises a ring-shaped multi-layer structure formed on the substrate.
12. The X-ray source of claim 10 , wherein the multi-layer structure comprises one or more trenches extending at least through the multi-layer structure.
13. The X-ray source of claim 12 , wherein at least one trench is a ring-shaped trench extending at least through the multi-layer structure.
14. The X-ray source of claim 12 , wherein at least one trench is a radial trench extending at least through the multi-layer structure.
15. The X-ray source of claim 14 , wherein each radial trench comprises a stress relief feature formed at a terminal end of the respective radial trench.
16. A method for manufacturing a multi-layer X-ray source target, comprising:
forming a thermally-conductive substrate;
forming two or more X-ray generating layers comprising X-ray generating material on the thermally conductive substrate, wherein the X-ray generating material in each X-ray generating layer, when formed, extends less than the full extent of the surface of the substrate;
between each X-ray generating layer, providing a thermally-conductive layer; and
disposing a thermally conductive top-layer over a first X-ray generating layer relative to a cathode-facing surface of the structure, wherein the top layer comprises a thermally conductive material having a thermal conductivity in a range from about 250 W/m-K to about 1700 W/m-K.
17. The method of claim 16 , wherein at least one of the X-ray generating layers comprises a ring or a plug of the X-ray generating material.
18. The method of claim 16 , further comprising cutting trenches within each X-ray generating layer using one or both of a laser or an energetic beam.
19. The method of claim 16 , further comprising etching one or more trenches prior to or after forming the two or more X-ray generating layers and the thermally-conductive layers.
20. The method of claim 16 , further comprising masking a portion of the thermally-conductive substrate prior to forming the two or more X-ray generating layers and the thermally-conductive layers.