Extraction of Magnetoplasmadynamic Thruster Design Guidelines through Optimization

Abstract

One of the chief drawbacks of MPD thrusters is their low thrust efficiency. This paper presents a numerical optimization of the thruster nozzle and of the distribution of the self-induced magnetic field that occurs in the nozzle, with the goal of developing nozzle design guidelines. This model accounts for the pressure gradient and the Lorentz force, and optimization was performed using a genetic algorithm. The results showed that (1) large improvements in performance can be obtained in a model representing a thruster of practical size; (2) optimal location of the nozzle throat was at 15 [%] - 30 [%] of nozzle length downstream of the inlet and the throat is an essential feature of the nozzle; and (3) the profile of the upstream portion of the nozzle (where most of the acceleration of the plasma occurs) is little affected by up-scaling of nozzle size.