Abstract
Hollow cathodes are electron sources used for the gas ionization and the beam neutralization in both ion and Hall effect thrusters (HETs). A reduction of power and propellant consumption from the cathode is particularly needed in small satellite applications, where power and mass budgets are inherently limited. Concurrently, the interest in high-power HETs is increasingly fostered for a number of space applications, including final positioning and station-keeping of Geostationary Earth Orbit (GEO) satellites, spacecraft transfers from Low Earth Orbit (LEO) to GEO, and deep-space exploration missions. As such, several hollow cathodes have been developed and tested at Sitael, each conceived for a specific power class of thrusters. A numerical model was used during the cathode design to define the geometry, in accordance with the thruster unit specifications in terms of discharge current, mass flow rate, and lifetime. Lanthanum hexaboride (LaB6) hollow cathodes were successfully developed for HETs with discharge power ranging from 100 W to 20 kW. Experimental campaigns were carried out in both stand-alone and coupled configurations, to verify the operation of the cathodes and validate the numerical model. The comparison between experimental and theoretical results are presented, offering a sound framework to drive the design of future hollow cathodes.
Highlights
Hollow cathodes based on thermionic electron emission are used in space electric propulsion to supply electrons for propellant ionization and beam neutralization of both ion engines and Hall effect thrusters (HETs)
The theoretical study paved the way to the development of several for Hall effect thrusters belonging to different power classes [8]
HC1 was experimentally characterized during a dedicated stand-alone test campaign, after which the cathode was coupled with the Sitael HT100D 100 W-class Hall thruster [14]
Summary
Hollow cathodes based on thermionic electron emission are used in space electric propulsion to supply electrons for propellant ionization and beam neutralization of both ion engines and Hall effect thrusters (HETs). Several numerical models have been developed to determine the plasma properties in hollow cathodes [4,5,6] In these models, experimental data are used as input. In these models, experimental data are used as input or assumptions are made to set the plasma density, the electron temperature, or the coupling voltage to the keeper [5]. A or assumptions are made to set the plasma density, the electron temperature, or the coupling voltage reduced-order model was proposed to overcome these limitations through the development of to the keeper [5]. The theoretical study paved the way to the development of several for Hall effect thrusters belonging to different power classes [8]. Hollow cathodes, for Hall effect thrusters belonging to different power classes [8]
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