Design of an Air-Breathing Electric Thruster for CubeSat Applications

The altitude range between 120 and 300 km is relatively unexplored with regard to space weather, atmospheric models, climate observations, the global electric circuit, remote sensing, and intelligence gathering. This altitude range is not conducive to in situ measurements due to the high magnitudes of drag that are experienced by satellites at these altitudes. The concept of air-breathing propulsion systems have been proposed to counteract drag. These propulsion systems produce thrust through electrostatic propulsion by ionizing the background neutral atmospheric particles. The atmospheric neutral particles that are the cause of drag at these altitudes are used as the fuel source for these air-breathing thrusters. Systems have been conceptually designed for larger satellites, but in this work we show that is possible for CubeSats to employ similar systems. CubeSats are a relatively new technology that have allowed low cost satellites to be built by a variety of entities including universities and private companies at low cost and with rapid development cycles. Due to current restrictions, CubeSats are not allowed to carry propellant. This limits CubeSats from maneuvering, formation flying, orbit raising, drag make-up, and deorbiting. However, this has not prevented the study and design of propulsion systems for CubeSats, with the anticipation of the propellant restrictions being lifted. In this research, a concept for an air-breathing ion thruster is designed for the use in 3U, 6U, 12U, and 27U CubeSats. The design is created to be modular to this system, and each component is discussed separately. An analysis is conducted to determine the best inlet shape for capturing atmospheric particles. This analysis is conducted using a 3D Monte Carlo simulator. The ionization of atmospheric particles is investigated, and issues with ionization of the particles given the design of the system are discussed. Based on the expected inlet capture efficiency and ionization efficiency, the thrust capabilities of the system are projected for the various CubeSat standard sizes in LEO altitudes (80 km to 600 km). Analysis of the thrust based on CubeSat size, voltage, solar activity, and ionization efficiency is also conducted herein. This work shows that it is possible to build air-breathing propulsion systems for CubeSats with thrust exceeding the local drag in LEO altitudes