High energy pulsed inductive thruster modeling operating with ammonia propellant

Numerical modeling of the pulsed inductive thruster operating with ammonia propellant at high energy levels utilized a time-dependent, two-dimensional, axisymmetric magnetohydrodynamics code which was augmented with a time-dependent plasma voltage model to properly account for plasma dynamics. Two idealized problems were used to verify the new circuit algorithm and showed very good agreement to the analytic solutions. Comparisons of the predicted current waveforms to experimental data exhibited excellent agreement for the first half period essentially capturing the dominant acceleration phase. Further validation proceeded by comparisons of the impulse for three different energy levels; 2592J, 4050J and 4608J and a wide range of propellant mass values. Predicted impulse captured both trends and magnitudes measured experimentally for nominal operation. Interpretation of the modeling results in conjunction to experimental observations further confirm the critical mass phenomenon beyond which efficiency degrades due to elevated internal energy mode deposition and anomalous operation.