Relationship Between Current and Mesh Cathode Structure for a Coaxial Cylindrical Diode

Cathode current is a key measure of the rated power of the diode and is closely related to the cathode structure. Compared with $\Pi $ cathode and helical cathode, the mesh cathode has been more widely used in high-power tetrode, because of its structural advantage. So far, the relationship between the space charge limited current (SCLC) and the cathode structure for thermionic emission mesh cathode diode has not been reported. In this article, we develop a calculation expression of the SCLC for the mesh cathode coaxial cylindrical diode, which is based on the calculation model of the helical cathode. The results show that the calculated values are in excellent agreement with the simulated values based on CST Particle Studio. In addition, we study the dependence of the SCLC of the mesh cathode diode with the change of the cathode height, radius of the cathode filament, anode voltage, and density of the mesh. It is helpful for the optimization of the cathode structure design of vacuum tubes and microwave tubes with the coaxial cylinder mesh cathode structure.