Fabrication and Emission Properties of Single Crystal Lanthanum Hexaboride Tip

Field emission cathode single tip was fabricated by electro-chemical etching method. The materials used here were single crystal lanthanum hexaboride (LaB₆), polycrystalline lanthanum hexaboride, molybdenum, and tungsten, respectively. Electron emission characteristics of single crystal LaB₆ cold cathode were studied in a diode test cell in vacuum system. When the distance between the single crystal LaB₆ tip and the anode was 0.2mm, current density of 1.25times10⁴ A/cm² was obtained at a pressure of 3.4times10^-4 Pa with DC-3000 V bias applied to the anode. Results show that single crystal LaB₆ cold cathode, due to its high current density, low evaporation rates, high stability, strong ability of antipoisoning and long life, is an excellent electron source, particularly fitting for traveling-wave tubes, klystrons and other large vacuum apparatus