Applied-field magnetoplasmadynamic thrusters, Part 1: numerical simulations using the MACH2 code

Numerical modeling of the NASA Lewis Research Center 100-kW, steady-state, applied-field magnetoplasmadynamic thruster is performed using the magnetohydrodynamics code MACH2 for a range of applied magnetic field strengths and discharge currents. Overall performance trends, obtained experimentally with argon propellant, are captured by the simulations. Magnitudes of plasma voltage vs applied field strength also agree well. Interrogation of the calculated flowfield offers a new visualization of applied-field magnetoplasmadynamic thruster operation, comprising the following elements: 1) the back electromotive force is the dominant contributor to the plasma voltage for the geometry examined; 2) viscous forces oppose applied azimuthal electromagnetic forces and limit the maximum rotational speed to a constant independent of applied field or current value; 3) viscous heating and conversion of thermal energy to axial directed kinetic energy is the main acceleration mechanism; and 4) the low-density, low-conductivity argon plasma for the regime examined does not interact with the applied field in the manner of a magnetic nozzle.