Air Force Research Laboratory high power electric propulsion technology development

Abstract

Space solar power generation systems have a significant impact on Electric Propulsion (EP) technology development.1,2,3 Recent advances in solar cell, deployment, and concentrator hardware have led to significant reductions in component mass, thereby decreasing power generation system specific mass. Combined with maneuvering requirements for Air Force and DoD missions of interest, propulsive requirements emerge that provide direction for technology investments. Projections for near- to mid-term propulsion capabilities are presented indicating the need for thrusters capable of processing larger amounts of power (100 – 200 kW), operating at relatively moderate specific impulse (2000 – 6000 seconds) and high efficiency (≫ 60%), and having low propulsion system mass (≪ 1 kg/kW). Two technology areas are identified and discussed in the context of the above thruster constraints. Concentric channel Hall thrusters are an extension of a mature technology, offering operation over expanded power levels and lower propulsion system specific mass at state-of-the-art (SOTA) efficiencies. Field Reverse Configuration (FRC) thrusters are a specific type of pulsed inductive accelerator that have the potential to operate up to MW power levels, at propulsion system specific masses even lower than concentric channel Hall thrusters, and on a wider range of propellants. However, FRCs are currently less mature than the Hall thruster variants. Comparisons of candidate technologies are evaluated with VASIMR, a well publicized high power EP device currently under development.