Current distribution and plasma acceleration in MPD arcjets with applied magnetic fields

Abstract

Current distribution and plasma acceleration mechanisms in MPD arcjets with applied magnetic fields are analyzed theoretically, based on induction and quasi-one-dimensional gasdynamic equations. The finite-element method is used to obtain current distribution and magnetic field patterns. The applied magnetic fields are of diverging type, and calculations are conducted in the cases of discharge currents of 1000 and 2000 A, and mass flow rate of 100 mg/s, for a conventional electrode geometry. Whether the magnetic Reynolds number R(m) is negligibly small or not, it is shown that current distribution on the cathode is not influenced by plasma flow, and the influence of it on current distribution is bounded in the downstream region. Information is presented concerning the relative importance of acceleration mechanisms in MPD arcjets with applied magnetic fields; it is also shown that although for most cases, an externally applied magnetic field is desirable, there exists the possibility that an efficiency-reducing current vortex will occur in the downstream region for the case of a strong magnetic field. 9 references.