Study on the electron emission characteristics of a thermal emission cathode with grid for micro-electric thruster

The Thermal Emission Cathode with Grid (TECG) is a type of cathode that operates without a working medium based on electric field modulation, which can be effectively adapted with micro-electric thrusters to perform high-precision space science missions. This research first analyzes the thermal electron emission theory, and the key dimensional and electrical parameters of the TECG, such as the grid width, the grid-emitter distance, the grid orifice diameter, the grid voltage, and the anode voltage, are simulated using the electromagnetic simulation software OPERA to obtain the optimal combination. Subsequently, the TECG was designed and machined using the parameters above for experimental testing and verification against the simulation results. The relative error between the experimental and simulation results was less than 20%. Under specific working conditions, the TECG's total emission capability can be increased by approximately 8 times, and the maximum emission current can reach up to 27.525 mA. Afterward, the research also discusses the electric field distribution in the entire space of the TECG, along with the electron distribution behavior caused by the electric field. Finally, after pointing out its shortcomings, the research provides guidance and prospects for future related work.