Plume Control of a Cusped Field Thruster
The cusped field thruster uses several permanent ring magnets of alternating polarity to create a multistage cusp magnetic topology. It has demonstrated a long lifetime because of reduced plasma losses to the discharge channel surface. However, the high beam divergence problem has not been solved in this type of thruster. The purpose of this technical note is to describe a plume control method to reduce its plume angle. The results show that the magnetic field intensity in the plume region and the shape of the last separatrix have great influence on plume divergence.
Experimental study on a variable magnet length cusped field thruster
Abstract The cusped field thruster is an emerging kind of electric propulsion equipment employing a cusped magnetic field to achieve potentially long lifetime. As important factors contributing to the thruster performance, the optimal channel length and magnetic field design are still uncertain. In order to research how magnet length affects performance, a variable magnet length cusped field thruster (VML-CFT) was designed and tested in Harbin Institute of Technology (HIT). By using modular magnets, VML-CFT can vary the length of each cusp stage. The design of VML-CFT is demonstrated in this paper. Experimental results show that certain length increase of the middle stage can improve the thruster performance. By analyzing experimental results with different magnet lengths, the thruster internal physical process can be inferred.
Status of the THALES Tungsten/Osmium Mixed-Metal Hollow Cathode Neutralizer Development
HKN 5000 hollow cathode neutralizers developed by THALES Electron Devices GmbH are based on a Tungsten/Osmium W/Os mixed metal cathode impregnated with Barium Calcium Aluminate as electron emitter. This cathode technology has a reduced work function and allows for reduced cathode temperatures and increased lifetimes compared to conventional Tungsten based cathodes. Being used as cathode material for the electron gun of Traveling Wave Tubes TWTs for satellite application, the THALES W/Os cathode technology has demonstrated more than 200 millions of successful operational hours in space. HKN 5000 neutralizers, which are being developed under support of German Space Agency DLR, are designed to deliver neutralizing currents of up to 5 A for ion thrusters, in particular for THALES High Efficiency Multi Stage Plasma Thrusters (HEMP- Ts). HKN 5000 breadboard (BB) models have shown very good performance with respect to low power and propellant consumption. Recently, HKN 5000 elegant breadboard (EBB) models have been developed, which are exclusively based on space-qualified manufacturing technologies derived from TWT production. This paper reviews the physics and technology of the THALES W/Os based hollow cathode neutralizers and presents operational and performance characteristics of the HKN 5000 BB and EBB models.