Design criteria assessment of a magnetic nozzle

Abstract

A model to assess the design criteria for a convergent-divergent magnetic nozzle is provided. This model is based on an ideal single-fluid magnetohydrodynamic flow assumption to evaluate the acceleration and detachment in the magnetic nozzle. A thermodynamic correlation of plasma internal energy during the propagation in a magnetic nozzle is presented. The result reveals the limitation of a magnetic nozzle on the conversion of internal energy to kinetic energy, where an upper limit of around 19% is derived, assuming plasma undergoes ideal conditions. In addition, criteria derived from the model also point out that a threshold on magnetic flux density exists to prevent the occurrence of flow discontinuity during propagation along the magnetic nozzle. The result hints at the essential role of the electric field on the acceleration processes of a magnetic nozzle, which can potentially be the key to overcoming the limitation of a magnetic nozzle’s performance.