Electron gun with one directly heatable and one indirectly heatable cathode

摘要

An electron gun with one directly heatable initial cathode (2), one indirectly heatable second blocking cathode (3) and one focusing electrode (17). The focusing electrode (17) presents an initial centering region (18) and, by means of supporting braces, the blocking cathode (3) is fixed concentrically in a carrier ring (19) presenting a second centering region complementary to the first centering region (18). This permits the blocking cathode (3) to be introduced into the focusing electrode from the back by means of the carrier ring (19), and the carrier ring (19) is secured by means of a locking ring (24).