| 摘要 |
In a cathode assembly, precise positioning of a cathode 10 relative to a grid plate 24 is achieved by mounting the cathode in a retaining ring 34 which is mounted in a housing 36. Both the ring 34 and housing 36 may be of ceramic material. In the preferred embodiment, three cathodes are similarly mounted within a single housing (Fig. 3, not shown), each being a dispenser cathode (10) capable of current densities up to and exceeding 10 Amperes per square centimeter and comprising a refractory material reservoir (14) containing a pellet of tungsten and barium calcium aluminate (16) sealed by a pellet (18) of porous tungsten or tungsten mixture. The reservoir/pellet assembly may be contained in a support cylinder to which the porous tungsten pellet may be welded. <IMAGE> |
