NUMERICAL-ANALYSIS OF A 2-DIMENSIONAL MAGNETOPLASMADYNAMIC ARCJET

The effect of electrode configuration on thrust characteristics of a t wo-dimensional magnetoplasmadynamic (MPD) arcjet was numerically inves tigated. A simple magnetohydrodynamics (MHD) model was developed and t he numerical results were compared with the experimental data for seve ral electrode geometries. To understand the features of the flowfield, we introduced a magnetosonic Mach number, which is defined as Local v elocity divided by a propagation speed of the MHD disturbance, Based o n the magnetosonic Mach number distribution of the flowfield, the mode l can explain the thrust characteristics of the MPD arcjet, especially the superiority of a short cathode under various anode configurations , Because the electromagnetic thrust is unaltered for the same anode c onfiguration, the electrothermal component of thrust makes a differenc e between the long and the short cathodes, With a short cathode config uration, the large heat deposition near the cathode tip, which is inev itable to MPD arcjets, can be confined in the submagnetosonic region w here the local now is accelerated to magnetosonic velocity, Then the t hermal deposition into the submagnetosonic region can be efficiently r ecovered through transmagnetosonic acceleration, resulting in a large thrust generation.