X-ray tube having reduced window heating
First Claim
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1. An X-ray tube assembly comprising:
- a) an X-ray tube cathode having a first electrical potential and including an electron emitting surface having an electron beam axis;
b) an X-ray tube anode spaced apart from said cathode, having a second electrical potential which is more positive than said first electrical potential, and including an X-ray target surface generally facing said electron emitting surface of said cathode and intersecting said electron beam axis at a focal point;
c) a generally-hermetically-sealed frame surrounding said cathode and said anode, spaced apart from said electron emitting surface and said X-ray target surface, and including an essentially-X-ray-transparent window having a perimeter and a point center of mass, wherein said focal point and said point center of mass define an X-ray beam centerline; and
d) a generally-non-electron-emitting electrode disposed within said frame, spaced apart from said electron emitting surface and said X-ray target surface and said window, and having a third electrical potential which is more negative than said second electrical potential,wherein said X-ray tube assembly is devoid of any electrode disposed within said frame, other than said anode, which attracts electrons.
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Abstract
An X-ray tube assembly having a cathode, an anode, and an electrode surrounded by a vacuum-enclosing frame. Electrons from the cathode strike a target surface on the anode. Some electrons produce X-rays which exit an X-ray transparent window portion of the frame. Other electrons are backscattered and go on to strike and heat the frame including the window region. The non-electron-emifting electrode typically has a negative electrical potential and is positioned to deflect the backscattered electrons away from the window region which reduces heating thereto and hence minimizes tube failure.
76 Citations
13 Claims
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1. An X-ray tube assembly comprising:
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a) an X-ray tube cathode having a first electrical potential and including an electron emitting surface having an electron beam axis; b) an X-ray tube anode spaced apart from said cathode, having a second electrical potential which is more positive than said first electrical potential, and including an X-ray target surface generally facing said electron emitting surface of said cathode and intersecting said electron beam axis at a focal point; c) a generally-hermetically-sealed frame surrounding said cathode and said anode, spaced apart from said electron emitting surface and said X-ray target surface, and including an essentially-X-ray-transparent window having a perimeter and a point center of mass, wherein said focal point and said point center of mass define an X-ray beam centerline; and d) a generally-non-electron-emitting electrode disposed within said frame, spaced apart from said electron emitting surface and said X-ray target surface and said window, and having a third electrical potential which is more negative than said second electrical potential, wherein said X-ray tube assembly is devoid of any electrode disposed within said frame, other than said anode, which attracts electrons. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An X-ray tube assembly comprising:
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a) an X-ray tube cathode having a first electrical potential and including an electron emitting surface having an electron beam axis; b) an X-ray tube anode spaced apart from said cathode, having a second electrical potential which is more positive than said first electrical potential, and including an X-ray target surface generally facing said electron emitting surface of said cathode and intersecting said electron beam axis at a focal point; c) a generally-hermetically-sealed glass frame surrounding said cathode and said anode, spaced apart from said electron emitting surface and said X-ray target surface, and including an essentially-X-ray-transparent window having a perimeter and a point center of mass, wherein said focal point and said point center of mass define an X-ray beam centerline; d) a casing surrounding and generally spaced apart from said frame; e) a dielectric liquid coolant disposed between said frame and said casing; and f) a generally-non-electron-emitting electrode disposed between said frame and said casing, and having a third electrical potential which is more negative than said second electrical potential, wherein said X-ray tube assembly is devoid of any electrode disposed between said frame and said casing which attracts electrons. - View Dependent Claims (13)
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Specification