Scandate dispenser cathode for 220 GHz 50W sheet beam travelling wave tube amplifier

Nanocomposite Sc₂O₃-added tungsten dispenser cathodes were tested in Cathode Life Test Vehicles (CLTV) with a Pierce gun configuration under CW mode. The emission performance for both dc and pulsed current density remained consistent. In CLTV #1, owing to perveance issue (there is 100 micron gap between focus electrode and cathode emission surface), 10 A/cm² dc current density can be acquired at practical temperature of 1120°C Br for more than 2000 hours. In CLTV #2 with reduced FE gap, 45 A/cm² dc current density is obtained.