Magnetoplasmadynamic Thrusters

Abstract

Abstract A brief account is given initially of the origins of the MPD thruster concept. The nature of the Lorentz force, constituting the basic accelerating process exploited in MPD thrusters, is analyzed. A simple model of ideal self‐field MPD thruster is then considered; to illustrate the basic thrust law and the ensuing scaling trends characterizing this class of device. The behavior of real self‐field MPD thrusters is then described with regard to deviations from the ideal electrical characteristics, highlighting the Hall and the back‐EMF effects and the role of Alfvén's critical ionization velocity. Onset phenomenology and the critical onset parameter are then introduced. The main theories proposed to explain onset phenomena are summarized, with particular regard to mass starvation, and instabilities. Applied field MPD thrusters and lithium propellant self‐field and applied‐field devices are then described. The major R&D efforts so far undertaken in this field worldwide are shortly reviewed. Finally, some concluding remarks are made as to the status and prospects of MPD propulsion.