Claims
- 1. An x-ray tube, comprising:
- an envelope for containing a vacuum;
- target means forming part of said envelope for emitting x-rays;
- an electron-beam accelerator assembly including:
- an indirectly heated cathode assembly having a cathode for emitting electrons;
- a shaped rotationally symmetric electrode surrounding said cathode;
- a primary shaped anode with a central bore spaced from said cathode for accelerating the electrons emitted by said cathode, said shaped electrode and shaped anode providing focusing fields which focus the electron beam to form a beam waist at the center of said bore;
- means external of said envelope for focusing said electron beam leaving the anode on said target means;
- support means external to said envelope for supporting said envelope for rotational movement; and
- means external of said envelope for deflecting said electron beam along a selected path as said envelope rotates such that said electron beam strikes selected portions of said target means as it rotates.
- 2. An x-ray tube as in claim 1 wherein said means for deflecting includes two magnetic coils and a ferromagnetic mirror plate arranged to function as a single quadrupole electromagnet, which has its axis parallel to and offset from the electron beam and which elongates the electron beam in a radial direction.
- 3. An x-ray tube as in claim 1 including ion clearing electrodes disposed between said primary anode and said target to sweep away from said electron beam positively charged residual gas ions.
- 4. An x-ray tube as in claim 1 in which said support means external of the envelope comprises a housing and bearings between said housing and envelope.
- 5. An x-ray tube as in claim 4 in which said housing envelope and bearing define a chamber for containing insulating fluid.
- 6. An x-ray tube as in claim 1 in which said target is fluid cooled.
- 7. An x-ray tube as in claim 1 wherein said means for deflecting includes two magnetic coils and a ferromagnetic mirror plate arranged to function as a single quadrupole electromagnet, which has its axis parallel to and offset from the electron beam and which elongates the electron beam in a radial direction.
- 8. An x-ray tube as in claim 4 including ion clearing electrodes disposed between said primary anode and said target to sweep away from said electron beam positively charged residual gas ions.
- 9. An x-ray tube, comprising
- an envelope for containing a vacuum;
- target means forming part of said envelope for emitting x-rays;
- an electron-beam accelerator assembly including:
- an indirectly heated cathode assembly for emitting an electron beam, wherein said cathode means includes an electron-emitting region mounted at the center of a rotationally symmetric Pierce-cathode configuration;
- a primary anode having formed therein an aperture through which the electron beam is accelerated by said anode, said anode and Pierce-cathode forming a beam waist at said aperture;
- means for focusing said electron beam on said target means;
- support means external to said envelope for supporting said envelope for rotational movement; and
- means external of said envelope for deflecting said electron beam along a selected path as said envelope rotates such that said electron beam strikes selected portions of said target means as it rotates.
CROSS REFERENCE TO RELATED APPLICATIONS
This is a continuation-in-part of a U.S. Pat. application Ser. No. 275,780, filed Nov. 23, 1988 now U.S. Pat. No. 4,993,055 by Roy E. Rand et al., and entitled "Rotating X-Ray Tube with External Bearings."
US Referenced Citations (3)
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
275780 |
Nov 1988 |
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