CubeSat Ambipolar Thruster (CAT)
CAT being set up for an experiment
Tested at PEPL
2013 – 2016
PEPL, NASA, DARPA, Phase Four Inc.
The CubeSat Ambipolar Thruster (CAT) is a thruster designed as a propulsion system for CubeSats. It relies on a radio frequency antenna to create a plasma in a ceramic liner. The radiofrequency wave efficiently ionizes the Xenon propellant and heats the electrons. Through the process of ambipolar diffusion, these electrons exit the generation region at high speeds. The resulting charge imbalance provides an electric field that accelerates the ions, generating thrust.
To further convert the electron thermal energy into thrust, a magnetic nozzle is applied. A magnetic nozzle consists of a diverging magnetic field that forces the plasma to expand outwards as well, cooling it and converting its thermal energy into directed thrust. The nozzle also induces azimuthal electron currents which in turn produce a magnetic field in the direction opposite of the nozzle. In this manner, the electrons form an electromagnet that pushes off of the thruster magnetic field, enhancing thrust.
Furthermore, CAT will be able to operate on a wide range of propellants. While a supply of Xenon is still ideal, it is difficult to bring such a supply into space. For extended missions throughout the solar systems, small thrusters must be able to adapt to whatever propellant they have nearby, a concept known as In-Situ Resource Utilization, ISRU. A thruster able to use a variety of propellants such as CAT will extend the range of small satellite missions.
The H9 Magnetically Shielded Hall Thruster
Hofer, R.R., Cusson, S.E., Lobbia, R.B., and Gallimore, A.D.
Performance of the H9 Magnetically Shielded Hall Thrusters
Cusson, S. E., Hofer, R. R., Lobbia, R. B., Jorns, B. A., and Gallimore, A. D.