Micro/nano-particle electrostatic accelerator for electric propulsion

Summary form only given: The nanoparticle field extraction thruster (NanoFET) is an electrostatic micro/nano-particle accelerator technology that is being developed for use as an electric propulsion system. Conceptually, NanoFET employs micro/nano-electromechanical systems (MEMS/NEMS) to transport, charge, and accelerate conductive particles. The propellant, via piezoelectric actuations, is fed from a storage reservoir through a charging grid that breaks up particle agglomerates. Above the charging grid, a stack of electrode gates is electrically biased to provide the necessary charging and accelerating electric fields, with charged particle passage through arrays of channels etched through the electrode stack. Particles can be charged to either polarity, so the need for a separate neutralizer is eliminated. Because the particulate propellant is electrostatically charged in NanoFET via contact with the charging electrode rather than ionized via electron impact collisions, the propellant's specific charge is readily adjustable. By changing the charging electric field or using particles of different densities or sizes, NanoFET can tune its propulsion performance for different mission needs. In addition, NanoFET may allow important advantages in terms of propellant storage and handling efficiency over gas or liquid propellant approaches. Micron-sized particles have been successfully transported, charged, and accelerated in the lab, and work is progressing towards scaling down the system to accommodate nano-particles. Key challenges to be addressed include overcoming inter-particle forces to permit acceleration of individual particles rather than agglomerations with a distribution of charge states and optimizing the allowable current density.