Fundamental Limit of Self-Field MPD Thruster Efficiency
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Fundamental Limit of Self-Field MPD Thruster Efficiency
Abstract
A fundamental upper limit, η, for the thrust efficiency of self-field magnetolpasmadynamic thrusters (MPDTs) is derived from the generalized Ohm’s law and the minimization of the volume integral of the square of the current density, which controls dissipation in the MPDT. It is found that η = 1/(1 + 4/(Rmci*ξ^4)), where ξ is the MPDT scaling number (the total current normalized by the current at which an equipartition of power occurs between thrust and ionization), and Rmci is the magnetic Reynolds number evaluated at ξ = 1.