Applied-field magnetoplasmadynamic thrusters, Part 2: analytic expressions for thrust and voltage

The new visualization of applied-field magnetoplasmadynamic thruster operation offered by numerical simulations with the MACH2 code is used to develop an analytic model. This model provides simple expressions for the thrust and voltage drop across the plasma that capture all of the trends and in most cases the magnitudes of a wide range of experimental data including tests at multiple laboratories on three propellants: argon, hydrogen, and lithium. It establishes that the thrust scales as the square root of the product of the applied-field strength, discharge current, and mass-flow rate. Voltage scales linearly with applied-field strength and is independent of discharge current and mass-flow rate. This model also provides additional insights that can be used to improve applied-field magnetoplasmadynamic thruster performance.