Patent ID: 9601300
Date: 2017-03-21
CPC Classifications: H01J

Claim:
1. A cathode element for a microfocus x-ray tube, comprising: a heatable filament formed of a wire for thermionic emission of electrons for generating an electron beam and a Wehnelt cylinder with a front end opening for the electron beam, characterized in that the cathode element is a replaceable unit for insertion into an adapted mounting of the microfocus x-ray tube including the Wehnelt cylinder and the filament comprises, at an electron beam emitting area of the filament, a first elongate extension extending in a first direction perpendicular to the electron beam and a second elongate extension extending in a second direction perpendicular to the electron beam, wherein a length of the first elongate extension differs from a length of the second elongate extension by not more than 50%, the first and second elongate extension formed by a plurality of wire portions arranged next to each other, the wire portions arranged so as to be spaced apart from each other by a distance less than or equal to a diameter of the wire, wherein the filament is centered relative to the front end opening.