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X-ray tube with sealing Disclosure Number: IPCOM000007535D
Publication Date: 2002-Apr-04
Document File: 2 page(s) / 54K

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X-ray tube with sealing

    A conventional X-ray tube comprises a source (cathode) for emitting electrons and a carrier (anode) which is provided with a material which generates X-rays as a result of the incidence of an electron beam emitted by the source. The carrier is disc- shaped and is rotatable about an axis of rotation. The source and the carrier are accommodated in a vacuum space. During the generation of the X-rays, the carrier is considerably heated by the impinging electrons.

    In a particular X-ray tube the carrier is rotatably journalled in the vacuum space by means of a dynamic groove bearing (1), which is schematically shown in figure 1. The bearing (1) comprises an inner bearing member (2), which is fixed to a housing of the X-ray tube not shown, and an outer bearing member (3), which is rotatable about the inner bearing member (2) and is mounted to the carrier (4). The inner bearing member (2) comprises a pattern of grooves (5) and the outer bearing member (3) comprises a circular cylindrical inner wall (6). Between the inner bearing member (2) and the inner wall (6) an annular bearing gap (7) is present, which is filled with a liquid lubricant (8). In the example shown, the lubricant is a liquid metal alloy of Ga, In and Sn. The liquid lubricant (8) does not only have a lubricating function, but also provides a large rate of heat transfer via the bearing (1) from the heated carrier (4) to the housing and further to a cooling system of the X-ray tube.

Between the carrier (4) and the outer bearing member (3) an annular chamber
(9) is present which is also filled with said liquid metal alloy of Ga, In and Sn. Thus, an improved rate of heat transfer is provided between the carrier (4) and the outer bearing member (3).

    As a result of the rotation of the carrier (4) about the axis of rotation (10), the liquid metal in the bearing gap (7) and in the annular chamber (9) is also rotated about the axis of rotation (10). As a result the liquid metal is subject to centrifugal forces, which are considerably high because of the relatively high density of th...