US 5,345,493 AGranted

X-ray tube with a reduced working distance

AssigneeU.S. Philips Corporation

InventorsJohannes D'Achard Van Enschut, Lourens Valkonet

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Abstract

In an X-ray tube for an X-ray analysis apparatus an optimized minimum working distance is achieved, together with an adequately high radiation yield, by integrated optimization of the radiation end of the tube, the position and the mounting of the exit window, and the electron-optical configuration in the tube. This results in an X-ray tube having a conical end, an angle of cone of approximately 45.degree. and the use of the cone as such in the electron-optical system of the tube. Exact determination of the anode position relative to a reference face outside the tube enables exact positioning of each individual tube in an analysis apparatus.

Claims9

Dependent claims

An x-ray tube comprising

a) an annular cathode (10) concentric with an axis of the tube and defining a cathode diameter;
b) an anode (14) for emitting x-rays, the anode being concentric with said annular cathode and contained within a diameter about said axis which diameter is smaller than the cathode diameter;
and
c) an envelope including:
i) an exit window (6), concentric with said axis, for receiving x-radiation emitted by said anode;
and
ii) a conical member (16), concentric with said axis, said conical member having a wide end and a narrow end, the wide end having a diameter larger than the cathode diameter, the narrow end supporting said exit window, said conical member acting as an electron-optical electrode which helps determine an electron path between said cathode and said anode, whereby no additional electrode is needed in a cathode-anode space of the tube and whereby a distance between a surface of the anode and a surface of an object to be irradiated is minimized.

4 more elements

Dependencies are inferred from the claim text.