Hybrid Electric Propulsion Using Gas Mixtures

Hybrid electric propulsion is a new technology that combines electrostatic and electromagnetic propulsions. The goal of this engineering study is to design a hybrid electric propulsion system that can provide a specific impulse that is higher than chemical thrusters, but uses less than 20 watts of power such that it can be used effectively in nanosatellites. This thesis describes RF electrothermal and electromagnetic thruster experiments that were undertaken to test the performance of gas mixtures, testing initially at lower temperatures a few hundred degrees above room temperature. A helium-nitrogen gas mixture is chosen in place of hydrazine because the mixture is non-toxic and does not require any heating equipment. In the study’s electrothermal testing, the 50% nitrogen – 50% helium gas mixture is shown to have a specific impulse of 96.3 seconds. In the propulsion system’s electromagnetic mode, 50% argon – 50% helium and 50% nitrogen – 50% helium gas mixtures have specific impulses of 603 and 801 seconds, respectively. In electrostatic propulsion mode, a 50% argon – 50% helium gas mixture has a specific impulse of 575 seconds, and 50% nitrogen – 50% helium gas mixture has a specific impulse of 805 seconds. The thesis describes subsequent experiments performed with the hybrid electric thruster operating in both electrostatic and electromagnetic propulsion modes over the course of two independent test cycles. The thesis provides a discussion on the expected performance of a space-based device utilizing the approaches studied in this investigation.