Power balance in a helicon plasma source for space propulsion

Abstract

Electric propulsion systems provide an attractive option for various spacecraft propulsion applications due to their high specific impulse. The power balance of an electric thruster based on a helicon plasma source is presented. The power balance is shown to be comprised of several variables, including the RF power supplied to the system, dissipative losses in transmission hardware, losses in the neutral confinement tube, uncoupled RF radiation, ionization power, and plume output power. A thermal model for the neutral confinement tube is presented whereby heat flux may be derived from thermal response data. Numerical simulation and experimental benchmarking are employed to validate this thermal model. A mapping of power consumption is presented. Comparison with experimental parameters indicates that 97% of the power supplied to the system is accounted for, suggesting that primary loss mechanisms have been identified. Avenues for improving the performance of the thruster, based on these data, are presented.