PAGE CONTENTS
Objectives
The primary objectives for project IFM Nano are:
- The adaptation of an established FEEP (field emission electric propulsion) ion thruster design for use on micro and nano satellites (particularly CubeSats). Such spacecraft could use the thruster either for continuous drag compensation in LEO or even as an efficient main drive.
- A full characterization and test campaign including functional and environmental tests to verify the design’s specifications and its fitness to operate reliably in orbit.
Challenges
- The IFM Nano Thruster shall be able to survive typical loads expected during ground handling and LEOP. In particular long and thin ‘needle’-like structures could be venerable to such loads.
- In the present design, only COTS components are used for thermal sensors and electronics. The radiation hardness of these components is not known. The thruster shall be able to operate, however, for at least a couple of years in a radiation environment typically expected in LEO.
- The functionality of the neutralization concept is based on extensive simulation of the electric fields, but no experimental verification has been conducted so far. Also the lifetime as well as lifetime limiting factors are currently not known.
- The plasma plume shape partly determines the thruster efficiency. Any plume divergence shall be minimised as much as possible. At present, the shape if the plume as well as its characteristics are unknown.
System Architecture
Mechanically, the thruster comprises a tank filled with the metal propellant and rigidly connected to the crown emitter. The extractor anode, which is part of the top plate, is separated via an isolator from the electronics compartment and the tank. An optional housing encloses all parts but is not required for mechanical stability.
Electrically, the thruster is commanded via the spacecraft bus via I2C or UART. The central command and control module is connected to the independent power supplies for the heater, the two cathodes (two separate supplies), the emitter, and the extractor.
Plan
The project starts with a PDR after which two engineering models are manufactured. Both engineering models are subjected to environmental tests including shock and vibration tests, thermal vacuum tests and performance tests. Three dedicated test campaigns are initiated:
- a test campaign for cathodes is performed to investigate failure mechanism as well as to select the most suitable cathode for our application
- the PPU subjected to low dose as well as high dose radiation tests to determine how much radiation the PPU equipped with COTS components can survive and to identify components most vulnerable to radiation
- a plume diagnostics system is designed and used to characterise the plume of the IFM Nano Thruster.
Current Status
The project is finished. All the work as outlined in the project plan is performed. Meanwhile, a successful in-orbit demonstration of the IFM Nano Thruster has taken place. A spin-off company was founded (Enpulsion GmbH) that commercially sells the thruster. Several thruster are currently flying in space. Derivatives of the IFM Nano Thruster are currently under development in a joint effort between FOTEC and Enpulsion.
