Ion production cost of a gridded helicon ion thruster

Abstract

Helicon plasma sources are capable of efficiently ionizing propellants and have been considered for application in electric propulsion. However, studies that estimate the ion production cost of the helicon plasma source are limited and rely on estimates of the extracted ion current. The ion production cost of a helicon plasma source is determined using a gridded ion thruster configuration that allows accurate measurement of the ion beam current. These measurements are used in conjunction with previous characterization of the helicon plasma to create a model of the discharge plasma within the gridded thruster. The device is tested across a range of operating conditions: 343–600 W radio frequency power at 13.56 MHz, 50–250 G and 1.5 mg s−1 of argon at a pressure of 1.6 × 10−5 Torr-Ar. The ion production cost is 132–212 ± 28–46 eV/ion, driven primarily by ion loss to the walls and anode, as well as energy loss in the anode and grid sheaths.