GB1247112A - An x-ray tube - Google Patents

Abstract

1,247,112. X-ray tubes. SIEMENS A.G. 16 Dec., 1969 [16 Dec., 1968], No. 61331/69. Heading H1D. An X-ray tube for operation in conjunction with an X-ray shielding member (1) (Fig. 1, not shown) to project a useful beam through a window (8) therein, includes a rotatable target electrode having an anode body 20 (e.g. carbon (graphite), beryllium, or low A.Wt. compounds of B or Be such as beryllium oxide), with an anode layer 27 of refractory material (e.g. high A.No. materials such as W, Ta, Re, U or alloys thereof or carbides of Hf, Ta, W, Th or U) of thickness, at least in the region forming the focal spot path of the X-ray tube, corresponding to the depth to which electrons penetrate at the highest acceleration voltage utilized, and the useful X-ray beam including X-rays emitted from at least part of the layer surface facing away from the anode body, and from at least part of the layer surface contacting the anode body, the X-rays from the latter surface being emitted via an X-ray permeable anode body region. Body 20 may be graphite, layer 27 of W up to 100 Á thick, e.g. 5 to 10 Á and the groove depth greater than the spot width. The upper outer edge of body 20 may be removed to increase the X-ray permeability, the lower portion impeding the transit of scattered electrons to the bulb. A 10 Á W anode layer may be on an annular bead (39), with two oppositely inclined surfaces (40), (41), (Fig. 5, not shown). Alternatively, the anode layer may be flat and moved up and down during rotation to avoid the central dark streak projection. A 3 mm. thick graphite annular projection (50) (Fig. 6, not shown) in conjunction with 3 mm. thick anode layer contacting region (51) ensures a homogeneous output. Projections (50) and (54) also intercept scattered electrons.