Electric Propulsion Simulation

Iodine is an attractive alternative propellant to xenon for space propulsion. However, because iodine has a more complex plasma chemistry, it is essential to understand the different reaction pathways and their influence on power consumption and gas heating to design  efficient  electron-emitting neutralizers. Radio-Frequency (RF) neutralizers minimize system erosion by avoiding direct electrode exposure to reactive iodine, in contrast to traditional hollow cathodes. However, system operation and gas heating remain poorly understood.

This work presents a global plasma model for iodine-fed RF neutralizers that incorporates an extended set of collisional reactions (103 in total), and tracks eight key species: I(²P_3/2), I(²P_1/2), I₂, I⁺, I₂⁺, I₂⁺⁺, I⁻, e⁻. Reaction rate coefficients are calculated using updated cross-section data, and the model accounts for the heating of atomic and molecular iodine .

Validation is performed using existing experimental data, with xenon cases used as a reference. Parametric studies investigate how RF power, mass flow rate, and neutralizer orifice dimensions influence gas utilization efficiency and electron energy cost. Understanding the underlying mechanisms responsible for gas heating is crucial and identifying specific reactions responsible for this heating helps to improve neutralizer design and operation.

These findings will aid the development and optimization of efficient iodine-compatible RF neutralizers for future electric propulsion systems.