Rotating-anode x-ray tube
AssigneeNational Research Development Corporation
InventorHugh Esmor Huxley
Life of this patent
Estimating the term…
Abstract
A rotating anode for an X-ray tube is constructed with a broad rim on to which the radiation - exciting electron beam is focused from a direction perpendicular to the axis of rotation. In order to distribute the thermal loading over the surface of the rim a transverse scanning motion is applied to the electron beam. Viewing the source conventionally from a direction nearly parallel to the axis of rotation the scanning spot is required to appear stationary and this is achieved by forming the surface of the anode rim in a uniform pattern of transverse channels. The scanning waveform must conform generally to the cross-section of the channels and the frequency and phase of the scanning motion must bear a defined relationship to the rate of rotation of the channel pattern.
Claims6
A rotating-anode X-ray tube comprising:
- an anode in the form of a generally circular wheel having a rim of uniformly serrated profile, the width of said rim being large relative to the depth of the serrations;
- means mounting said anode for rotation about the axis of said wheel;
- means for bombarding said rim with an electron beam directed transversely to said axis so as to impinge on a spot which has dimensions small relative to the width of said rim and is movable across the width of said rim by deflection of said beam;
- and
- an envelope surrounding said anode and said bombarding means and provided with a port which will permit the emergence from said envelope, in a direction nearly parallel to said axis, of X-rays generated by the impingement of said electron beam on said spot.
An X-ray generator comprising:
- a rotating-anode X-ray tube having an anode in the form of a generally circular wheel having a rim of uniformly serrated profile, the width of said rim being large relative to the depth of the serrations, means mounting said anode for rotation about the axis of said wheel, means for bombarding said rim with an electron beam directed transversely to said axis so as to impinge on a spot which has dimensions small relative to the width of said rim and is movable across the width of said rim by deflection of said beam, and an envelope surrounding said anode and said bombarding means and provided with a port which will permit the emergence from said envelope, in a direction nearly parallel to said axis, of x-rays generated by the impingement of said electron beam on said spot;
- drive means for rotating the anode of said tube;
- means for operating the bombarding means of said tube;
- means for cyclically deflecting the electron beam generated by the
- operation of said bombarding means to cause the spot on which said beam impinges to scan to and fro across the rim of said anode with a scanning waveform conforming generally to the serration profile of said rim;
- and
- means for synchronising the operation of said drive means and said
- deflecting means so that the frequency of the scanning of said spot is equal to the rotational frequency of said anode multiplied by the number of serrations on said rim and so that said spot will lie respectively on the crests and in the troughs of said serration profile when it is respectively nearest to and furthest from the port of said tube;
- whereby said spot will appear substantially stationary when viewed through said port in a direction lying in a plane passing through the axis of rotation of said anode and making with said axis an angle whose tangent is equal to the ratio of the depth of said serrations to the length of the scan of said spot across said rim.
Dependencies are inferred from the claim text.