2-D Extended Fluid Model of Applied-Field Magnetoplasmadynamic Thruster with Solid and Hollow Cathodes

In this paper, a 2-D model for simulation of an applied-field magnetoplasmadynamic (AF-MPD) thruster with solid and hollow cathodes was built using COMSOL Multiphysics. Extended fluid model was used for self-consistent simulation of discharge processes in the thruster. Ion energy balance equation was developed and added to extended fluid model. A viscously dominated steady-state fully formed gas flow was considered with argon gas used as a propellant. Electron transport properties as well as rates of electron-impact reactions were calculated using electron energy distribution function. Plasmachemical reactions taken into account included direct and stepwise ionization of argon atoms, excitation of metastable levels, three-body and radiation recombination, and so on. Coupling fluid equations with Poisson equation for electric potential allowed for self-consistent description of plasma and sheaths. Distribution of such discharge parameters as charged and excited particle densities and fluxes, charged particles' mean energies and temperatures, and gas temperature and electric potential were obtained. Comparison of simulation results allowed for concluding that using hollow cathode in an AF-MPD thruster can contribute to power efficiency and lifetime of the device.