The Effect of Anode Configuration on Hydrogen MPD Thruster Performance: A Numerical Study

Abstract

The flowfields of a self-field magnetoplasmadynamic (MPD) thruster using hydrogen propellant were numerically simulated with a physical model incorporating the ion-slip effect. Thrust performance was investigated for two anode configurations, namely, straight anode and flared anode at discharge currents between 5 to 8 kA. Simulation results show that thrust efficiency increases with increased discharge current for the straight anode, while for the flared anode, thrust efficiency tends to decrease; this opposite trend is caused by the ion-slip effect. When comparing thrust characteristics, thrust for the flared anode was found to be larger than that for the straight anode, but the advantage of the flared anode diminishes at higher discharge currents due to strong pinching and consequent pressure depletion in the vicinity of the flared anode surface. This pressure depletion leads to large electric power consumption owing to the ion-slip heating. That is, at lower pressures, the ion-slip effect becomes more significant because collisions between ions and neutral atoms are not frequent.