Design of the Faraday cup for a Multi-Layer Insulator Vacuum Arc Thruster Characterization

CubeSats are nanosatellites used for space research. This experiment focuses on developing a propulsion system for CubeSats. The vacuum arc thruster is an electric propulsion system utilized in space. This thruster’s design incorporates a thin layer of graphite between the cathode and anode, enabling the thruster’s ignition voltage in vacuum to be lower than 1 kV. This study proposes a multi-layer insulation design to replace the insulation layer in the vacuum arc thruster and the graphite layer covering it. This insulation layer utilizes the physical phenomenon of triple junction, where graphite and polytetrafluoroethylene (Teflon) adhere to each other. This design facilitates the easier generation of plasma at the interface of two different materials, ensuring stable operation of the thruster. Furthermore, the study also devises a rapid Faraday cup for measuring the vacuum arc thruster. This measurement system is better suited for pulse-type plasma sources, as it reduces signal reflection by considering impedance matching within the measurement system itself. By comparing the signals from the thruster discharge and the Faraday cup reception, the time of flight (TOF) method is then employed to calculate the plasma plume velocity. The experiment involves altering the distance between the thruster and the Faraday cup, analyzing plasma and flow velocities at different positions, and correcting the measurement results. Ultimately, in combination with erosion rates, the study determines the thrust magnitude of the thruster.