Speaker
Description
Since the first flight of a Field Emission Electric Propulsion (FEEP) thruster in 2018 in a joint IOD by ENPULSION and FOTEC, more than 300 ENPULSION FEEP systems have been launched, including over 200 heritage NANO systems, as well as an increasingly large number of successor products. These include the higher power MICRO systems and the updated NANO R3 and NANO AR3 systems. All these FEEP propulsion systems are based on passively-fed, Indium-based liquid metal FEEP technology, based on liquid metal ion source heritage developed at FOTEC. The passive propellant feed system in combination with a propellant that is in solid state during integration and launch make FEEP systems especially attractive for small satellite missions and missions that focus on simple, fast and cost-efficient integration and launch campaigns.
In these FEEP systems, thrust is generated through electrostatic acceleration of ions extracted from a liquid propellant by suspending the liquified metal propellant in porous, sharp emitter features.
This emitter including propellant is then biased to high voltage with respect to a counter electrode called extractor to induce a Taylor cone, leading to ion emission at the apex of the Taylor cone. To increase thrust, 28 emission sites are arranged in a characteristic crown shaped emitter geometry for the NANO thrusters, achieving thrust levels in the order of 350 µN. To increase thrust levels, 4 of these emitter crowns are operated in parallel in the MICRO thruster, allowing thrust levels
at nominal 1 mN. Depending on emitter and extractor voltage settings, propulsion systems can be operated in a specific impulse range from approx. 1000 to beyond 4000 s. The NANO AR3 system is an evolution of the 0.35 mN NANO R3 propulsion unit that adds beam steering capability without moving parts by differential throttling of regions of the ion emitter, utilizing three independently controllable extractor segments.
This work provides a statistical overview of previous missions employing FEEP propulsion systems, and discusses selected missions and applications enabled previously by this technology