X-ray tube with variable focus
AssigneeSiemens Aktiengesellschaft
InventorsPeter Schardt, Erich Hell
Life of this patent
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Abstract
An x-ray tube has an evacuated housing in which an electron-emitting cathode is rigidly mounted and a rotating anode having an anode dish rotatable by a drive arrangement, which is struck by the electron beam, accelerated with an electrical field, for producing x-rays. An electromagnetic system for the deflection and focusing of the electron beam has a number of current-permeated coil elements. The cathode generates a rotationally-symmetrical circular beam, and the rotational axis of the anode dish is offset from and parallel to the axis of the electron beam by the average radius of the anode dish edge. The electromagnetic system generates a dipole-free quadrupole field that deforms the electron beam cross-section.
Claims13
An x-ray tube comprising:
- an evacuated housing;
- a cathode rigidly mounted in said evacuated housing, said cathode emitting an electron beam having a substantially circular cross-section, and propagating along a beam axis;
- a rotating anode having an anode dish disposed in said housing and means for rotating said anode dish around a rotational axis, said anode dish having an annular edge having an average radius with regard to said rotational axis, and said rotational axis being parallel to and offset from said beam axis by said average radius;
- and
- electromagnetic means for deflecting and focusing said electron beam onto said anode dish and for generating a dipole-free quadrupole field for deforming said cross-section of said electron beam.
Dependencies are inferred from the claim text.