Modeling and Analysis of a Megawatt-Class Magnetoplasmadynamic Thruster

The magnetohydrodynamic code MACH2 is utilized to investigate the operation and performance of a megawatt-class, quasi-steady, self-field magnetoplasmadynamic thruster. The numerical results are validated by comparisons to experimental data and offer significant insights into this regime of operation. Specifically, operation at 0.5-6 MW and 1.37 g/s shows incomplete hydrogen-propellant ionization that is dominated by electron-neutral collisions, which in turn increase the plasma voltage, but do not substantially increase thrust. Acceleration is of a hybrid nature, transitioning from primarily electrothermal to predominantly electromagnetic with increasing current level. Detailed interrogation of energy deposition shows significant deposition to internal modes, as opposed to external-circuit-element losses and electrode losses via fall voltage and thermal conduction, even at the higher power levels. These frozen-flow and radial-momentum losses can be reduced while the system still operates with minimum power penalty by proper expansion of the flow.