Progress on the Implementation of a First-Principles Model of the Anomalous Momentum and Heat-Transfer in Hall2De

Building on plasma instability theory, we previously developed a first principles model for the electron momentum transfer in Hall thrusters in which short-wavelength electron cyclotron drift instability modes saturate at low turbulence levels while longer-wavelength lower hybrid modes grow to provide the observed anomalous electron momentum exchange, yielding a closed-form expression for the momentum and heat transfer collision frequencies in terms of local plasma variables. In this article we report on the implementation status of this model in Hall thruster simulations. We find that when the model is employed in simulations that make use of the generalized Ohm’s law, the axial electron current density becomes a function of the electron temperature primarily, making the determination of the plasma potential from current conservation numerically difficult. We propose that a coupled approach in which the electron temperature, current conservation, and generalized Ohm’s law equations are solved together may improve the numerical stability of the method. In a parallel effort, motivated by recent promising results from fellow researchers at SPARC Industries who achieved stable simulations using our closed-form model in a 2½-D axial-radial fully kinetic Particle-in-Cell (PIC) code, we have developed a 1-D full electron momentum solver that accounts for electron inertia. This code has been verified against simulations that make use of the generalized Ohm’s law. Although computationally intensive and, therefore, impractical for engineering applications, we plan to use this code to better understand the 2½-D PIC simulations and to learn how we might be able to achieve stable numerical simulations with our anomalous momentum-transfer model in engineering codes like Hall2De.