Numerical Phenomenology of Plasma Flow Near the Electrodes of a Magnetoplasmadynamic Thruster

To simulate the plasma flow in a magnetoplasmadynamic thruster, with mass flow rate of 4g/s and total discharge current of 16 kA, the magnetohydrodynamic equations accompanied by an anode sheath model have been solved. In this model, the flow through anode sheath region has been considered as a collisionless and unmagnetized plasma. Under this circumstance, by determining the densities of electrons and ions, and by discretizing the Poisson’s equation, potential drops along the anode surface have been obtained. The numerical simulation has properly revealed the phenomena such as dense internal flow, three jets and hot spot near the cathode. Also, the acceleration mechanism of exhaust plume has been justified based on the concept of virtual nozzle and cathode jet phenomenon. The values of maximum temperature and thrust have been predicted in good agreement with the other numerical and experimental data, with the errors less than 3.5%. Moreover, electrical characteristics of plasma in vicinity of anode such as the inverse dependence of anode fall with current density have been modeled in good accordance with the measured data.