Study of channel length effect on low power HEMP Thruster

The HEMP Thruster, also known as “cusped field thruster” becomes a candidate micro thruster of new generation space observation missions for its low complexity, potential long life over a wide range of thrust. As one of the main parameters of thruster, channel length selection is required in the downscaling of cusped field thruster. Three low power thrusters with different channel length are designed to discover the effect on performance and discharge characteristics. Due to the complexity of the ionization and acceleration process of the special cusped magnetic field, the plume is diagnosed by a Faraday probe and a retarding potential analyzer, and a Partial-In-Cell simulation is carried out to analyze the discharge mechanism. The result shows that lengthen of channel length has a diminishing positive effect on propellant utilization, but a negative effect on the total efficiency and kinetic performance at the same time. Decisive factors are discovered through the study on four internal efficiencies, with crucial physics process analyzed in the numerical simulation, which provides an important reference for the downscaling of the electric propulsion devices and similar low-temperature plasma discharge conditions.