SIMPLE FORMULATION OF MAGNETOPLASMADYNAMIC ACCELERATION

A simple formulation of magnetoplasmadynamic acceleration has been mad e 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 U=mu0J(D)2/(mu(A)) (J(D) is the discharge current, m is the mass flow rate of working fluid, U A is the Alfven's critical velocity, and mu0 is the permeability in va cuum); (2) the ratio of an applied to self-induced magnetic fields; an d (3) an electron Hall parameter. An exhaust velocity calculated using the formula agrees well with the experimentally measured value.