Determination of the components to be taken into account when calculating the total mass of working substance of an electric propulsion system based on a Hall thruster

Abstract

The total impulse is one of the main requirements for a spacecraft propulsion system. Its fulfillment depends on the specific impulse of the thruster and the propellant mass. The propellant mass consists of a working and a non-working reserve. The working reserve provides the required total impulse, and the non-working reserve compensates for the remaining propellant and other possible losses throughout the lifetime of the spacecraft. Accurately calculating the required propellant mass is critical: a shortage will lead to mission failure, and an excess will increase the weight and cost of the spacecraft mission. There are various methods for determining the required propellant mass, including: using the Tsiolkovsky formula; using the total impulse and specific impulse; using the second mass flow rate and total thruster operating time; taking into account the margin factor; taking into account the remaining propellant in the tank; taking into account the leakage of propulsion system elements. The first three methods take into account only the working reserve of the working substance, while the other three take into account additional factors, such as the remaining working substance and leakage losses. However, none of these methodologies fully cover all operational factors for a Hall-based electric propulsion system, which can lead to insufficient fulfillment of the required total impulse. For a more accurate determination of the total propellant mass, it is proposed to take into account the following components: working substance mass; reserve for compensation of residues; reserve for compensation of losses due to leaks; reserve for compensation of losses during preparation for the first start-up of the thruster; reserve for compensation of losses during each start-up and shutdown of the thruster; reserve for compensation of filling error. The proposed methodology improves the accuracy of determining the required propellant mass for the Hall-based electric propulsion system, ensuring a rational reduction in their quantity.