Characterization of Circular Arc Electron Source for Air Ionization in a Self-Neutralizing Air-Breathing Plasma Thruster*

Nowadays interest in air-breathing plasma propulsion for very low earth orbit applications is increasing. To this end, air-breathing plasma thrusters utilize incoming air as a propellant that is ionized and then consequently accelerated to produce thrust. This talk will present a unique concept for air-breathing plasma thrusters in which ionization and acceleration occur without slowing incoming air. In addition, by varying electron energy it has been demonstrated that both positive and negative ions can be extracted. This configuration could potentially eliminate the complexity of using a collimator reducing the drag. Typically, an air-breathing plasma thruster would require an external neutralizer to inject electrons for ion beam neutralization while a self-neutralizing air-breathing plasma thruster utilizes both positive and negative ions to achieve beam neutralization. This talk focuses on the ionization aspects of air-breathing thrusters through the development of radial magnetized arc electron source. This source consists of a circular configuration of a metallic arc plasma source coupled with a positively biased grid to extract electrons and control electron energy. It was demonstrated that radial electron source leads to enhanced ionization of airflow. The effect of external parameters on the source showed that the shape and size of arcing regions/intensity varied. While the grid underwent deposition of about 600 microns, the conductance was observed to increase/saturate with time and bias voltage indicating an electrically "self-healing material