MPD thruster scaling

Full scale and half scale versions of the Princeton Benchmark and Flared Anode self-field MPD thrusters have been investigated to determine the influence of scale and design upon MPD behavior. Thruster performance determined by impulsive thrust and terminal voltage measurements is found to depend primarily on propellant flow rate and the ratio of electrode radii, but not on thruster size. Current distributions obtained from magnetic field probes are independent of scale for both thruster designs. Voltage depends upon current, electrode geometry, and propellant flow rate. This behavior agrees qualitatively with calculations based on a fundamental MHD formulation.