Thermal Evaporation/Emission Properties of Sr-Doped Emission Active Coatings of M-Type Cathode

The thermal emission properties of self-developed M-type cathode,an advanced space vacuum electronic devices(VEDs)and fabricated with the Sr-doped conventional emission active coatings deposited by impregnation,were characterized with X-ray diffraction and pulsed emission and evaporation tests.The influence of the Sr-content on the thermal evaporation and emission rates was investigated with AM1#/AM2# samples comprised BaAl₂O₄,SrAl₁₂O₁₉,Ba₃Al₂O₆,CaAl₂O₍4)and BaAl₂O₄,Sr₃Al₂O₆,Ca₅(Al₃O₇)₂,Ba₃CaAl₂O_7,respectively.The results show that the Sr-doping matters.Specifically,measured at 1060℃,the evaporation-rates of AM1# and AM2# samples decreased by 49.95% and 71.87%,respectively;and evaluated at 1100℃,the evaporation rates were 40.27% and 61.45% lower than that of conventional dispenser cathode,respectively.As the Sr-content increased the pulsed emission current density and thermal evaporation rates decreased.However,the decreased emission rate of Sr-doped M-type cathode still meets the stringent requirements of VEDs.