Seminars

Air-breathing electric propulsion (ABEP) has emerged as a promising technology for sustained operation in very low Earth orbit (VLEO), where the surrounding atmosphere can be utilized as propellant. This work computationally investigates two ABEP concepts under VLEO-relevant conditions. The first employs a magnetized high-frequency ionizer, modeled as a capacitively coupled radiofrequency discharge in an E x B configuration. A 1D-3V particle-in-cell Monte Carlo collision (PIC-MCC) model using N2 as a surrogate gas shows that, under extremely rarefied conditions (i.e., ≤ 0.1 mTorr), sustained breakdown occurs within a narrow regime and requires combined magnetic and electrostatic confinement with high frequency excitation. The second concept is a gas-fed coaxial electromagnetic plasma accelerator. Using a two-dimensional resistive magnetohydrodynamic (MHD) model with a plasma-vacuum interface tracking algorithm, this work shows that initial gas loading governs discharge mode formation, and thermochemical nonequilibrium persists throughout the discharge. The magneto-deflagration mode produces high exhaust velocities (~65 km/s), whereas magneto-detonation introduces shock-related thermal losses and lower velocities (~30 km/s). Comparisons with experiments show agreement in plume structure, exhaust velocity, impulse bit, and electron temperature. A nine-species, three temperature nonequilibrium MHD model is developed and shows that a non-negligible fraction of energy remains stored in chemical form as a non-propulsive energy sink, while the vibrational contribution remains minor and plume regions are rich in O+ and N2+. Moreover, Lorentz mechanical power dominates the deposited electromagnetic power, with comparable exit kinetic power. Higher input power shifts the discharge toward a more ionization dominant state, sustaining higher electrical conductivity and stronger Lorentz-driven acceleration.