X-ray tube with a low-temperature emitter

摘要

An x-ray tube has an anode and an electron emitter from which an electron beam emanates, the electron beam impinging the incident surface of the anode in a focal spot from which a useful x-ray beam emanates. At least in the region of its electron-emitting surface, the electron emitter is formed of an electron-emitting material that has a lower electron affinity than tungsten (a low-temperature emitter). Further, an apertured diaphragm at anode potential is arranged between the electron emitter and the anode and through which the electron beam passes. As electron-emitting material, the electron emitter contains lanthanum hexaboride (LaB6) or an alloy of the systems iridium/cerium (Ir/Ce) or iridium/lanthanum (Ir/La) systems.