Abstract: Two-dimensional （2D） space charge limited current （SCLC） of an electron gun based cylinder pla- nar structure is studied. The relation of the 2D SCLC varying with many parameters, such as the distance between the cathode and the anode, cathode voltage, work function, cathode temperature as well as the cathode structure, is investigated in detail, which is more plentiful than that of Child-Langmuir law. A practical E-gun is designed and its SCLC and emitting performance are experimentally explored. The experimental result of the SCLC agrees well with that of 2D model.

Key words: planar electron gun, 2D space charge limited current, electronic vacuum device