| 摘要 |
An x-ray tube comprises an envelope, an anode target rotatably mounted within the envelope, and a cathode mounted within the envelope and spaced relative to the anode. The cathode includes an electrically insulative base defining an x-ray transmissive window therethrough, a recess formed within the electrically insulative base adjacent to a peripheral portion of the x-ray transmissive window, a filamentary electrode received within the recess, a first metalized conductive surface formed on a surface of the recess on one side of the filamentary electrode, a second metalized conductive surface formed on a surface of the recess on an opposite side of the filamentary electrode relative to the first metalized conductive surface and substantially electrically isolated relative to the first metalized conductive surface, a first terminal electrically connected to the first metalized conductive surface, and a second terminal electrically connected to the second metalized conductive surface. The electron beam size, shape, and/or direction emitted by the filamentary electrode is controllable by controlling a voltage differential between the first and second metalized surfaces.
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