Investigation of a La2Hf2O7 Direct-Heated Long Lifetime Cathode

In order to prolong the service life and high-temperature stability of direct-heated cathode, a novel cathode is proposed and prepared, in which La2O3, Gd2O3, and HfO2 are used as raw materials for the first time. The X-ray diffraction (XRD) structure characterization shows that emission material consists of La2O3 and La2Hf2O7 two compounds. The thermionic emission results indicate that this kind cathode can supply a current density of about 5.5 A/cm2 at 1600 °C. The energy dispersive spectroscopy (EDS) detection manifests the emission material distributes homogeneously around the W–Re base. The cathode has been working stably for 10 920 h without obvious fall at 1550 °C with the loading of 0.65 A/cm2 in life test process.