![]() The current research effort focuses on expanding the application envelope of these hollow cathode thrusters to C12A7 inserts and thus replacing the heater, and on investigating potential design optimizations by conducting a design parameter study. The first concept generates thrust electrothermally and has already been extensively studied at the University of Southampton with satisfactory results using and modifying the space-qualified hollow cathodes of the T5 and T6 ion thrusters. A third electrostatic hollow cathode thruster concept is currently under development but will be presented in a different publication. This publication is intended to present the early development progress and first test series of two propulsion systems that will be continuously improved in the future. The goal of this research effort is to benefit from the considerable advantages that come with heaterless hollow cathodes while relying on a vast body of theoretical literature to optimize the devices. In this context, two different propulsion concepts have been designed and realized that take advantage of the basic characteristics of hollow cathodes. As part of the H2020 E.T.Pack project that aims at developing a de-orbit kit for spacecraft using an electrodynamic tether, research on hollow cathodes and spin-off devices using the low work function material C12A7 is being conducted at Technische Universität Dresden. The technological maturity of hollow cathodes is attractive for stand-alone spin-off devices that could be of interest in various fields of application in the space industry. Although the physics of hollow cathodes are complex, they prove to be reliable and efficient electron emitters with lifetimes generally exceeding tens of thousands of hours even at high extraction currents. Hollow cathodes are an essential part of electric propulsion systems and have been the subject of extensive theoretical and experimental research for decades. Initial tests with C12A7 were not successful, but the functionality of the concept was shown by thrust measurements using a thoriated tungsten wire as an electron emitter. The second thruster concept is a novel electromagnetic device in which charge carriers in a plasma discharge are accelerated by an applied magnetic field that is orthogonally oriented to the discharge current. The influence of different geometric parameters on the discharge properties and the performance is investigated and presented. ![]() Initial thrust measurement tests were carried out which showed thrust levels well above cold gas thrust, but low thrust efficiencies. The first concept represents an electrothermal thruster which generates thrust by expanding and accelerating a heated propellant in a nozzle. Both devices represent millinewton thrusters that take advantage of thermionic electron emission using the low work function materials C12A7, LaB6, and thoriated tungsten in different design configurations. Two electric propulsion concepts have been developed at Technische Universität Dresden as spin-off devices of regular hollow cathodes and initial testing has been conducted.
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