Simple formulation of magnetoplasmadynamic acceleration

A simple formulation of magnetoplasmadynamic acceleration has been made based on energy conservation relations and a generalized Ohm’s law. An exhaust velocity is expressed using three characteristic parameters: (1) a dimensionless characteristic velocity Ũ≡μ0J2D/(ṁuA) (JD is the discharge current, ṁ is the mass flow rate of working fluid, uA is the Alfvén’s critical velocity, and μ0 is the permeability in vacuum); (2) the ratio of an applied to self-induced magnetic fields; and (3) an electron Hall parameter. An exhaust velocity calculated using the formula agrees well with the experimentally measured value.