Single-Unit Chemical/Electric Propulsion System?for Enhanced On-Orbit Maneuverability

Electric propulsion systems have proven to be an extremely valuable asset to satellite operators due to their excellent efficiency, but they are limited in their application by the low thrust they are able to produce. As a result, satellites must also be equipped with a high thrust, low efficiency chemical systems to carry out certain maneuvers that require fast reaction, like threat response or debris avoidance. As more complicated and maneuver-intensive mission sets like OSAM are being developed, and the overcrowding of the near-Earth environment increases, the need for more complicated maneuvers increases. Satellite operators need systems that maximize life and capability on orbit without sacrificing cost and payload capabilities.  Hybrid propulsion solutions address this need by combining chemical and electric propulsion systems. Current hybrid systems fall into two categories: chemical-electrothermal hybrid systems, and chemical-electrostatic. Chemical-electrothermal systems employ conventional chemical thrusters for high-thrust operations and either arcjets or a resistojets for high efficiency operations. This system has the advantages of simplicity, being able to operate on a single shared propellant, but suffers from a relatively low specific impulse, below 800s. Chemical-electrostatic systems consist of an independent system of conventional chemical thrusters and an independent system of Hall effect or gridded ion thrusters to accomplish the mission. The use of these electric thrusters has the advantage of much greater efficiency than the former, exceeding 1500s of specific impulse, but the system introduces greater complexity and mass requirements by requiring two separate propellant storage and feed systems, one for the chemical thruster, and one for the electric thruster. Another drawback of chemical-electrostatic systems is that it requires the use of scarce and expensive xenon gas as the propellant for the electrostatic thrusters.  We propose a third category of hybrid propulsion systems for use on satellites; a Chemical-Electromagnetic architecture enabled using Applied Field Magnetoplasmadynamic (AF-MPD) electric propulsion. AF-MPD thrusters overcome many of the drawbacks of both other systems, operating on a shared propellant with the chemical system, while reaching high Isp above 4000s. Hence, they can offer a simple, powerful, and flexible propulsion system which will simultaneously reduce complexity by using shared propellant tanks and feeding systems, while offering a more capable propulsion solution to enable the advanced spacecraft and mission sets of tomorrow.