A New Impregnated Dispenser Cathode

To meet the demand of terahertz devices, we develop a new type impregnated dispenser cathode. This cathode is impregnated with an active substance with molar ratio of 26BaO·29SrO·8Sc₂O₃·7CaO·Al₂O₃. We test its emission performance, practical work function distribution, and surface composition, and analyze the mechanism of the high emission performance. At 1100°CB, the pulse current density is 171.6±2.8 A/cm², 5.4 times of that of an M-type cathode. The peak work function of Miram curve is ~1.570 eV. Ba, Sc, Ca, Al, and O atoms are detected on most surfaces of tungsten grains. It is proposed that the Ba-Sc-Al-Ca-O layer on the surface of the cathode is responsible for the excellent emission performance.