inductive plasma accelerator, plasma acceleration, inductive accelerator, inductive mass-driver, plasma
Adam Martin, Richard Eskridge
Propulsion Research Center, Science and Technology Directorate, NASA Marshall Space Flight Center, XD22 Huntsville, AL 35812, USA
Abstract. A single-stage pulsed inductive plasma accelerator was modelled as an inductive mass-driver, with the plasma treated as a rigid slug that acts as the armature. We derive a set of coupled dynamic-circuit equations, with dimensionless coefficients. The functional form of the mutual inductance profile, M(z), was calculated using the magnetic field solver QuickField; an exponential form for M(z) was found to be accurate for a variety of coil-slug geometries. A parametric study of the solutions to the equations was performed in order to determine the conditions that yield high coupling efficiency. High inductance, multi-turn drive-coils yield the highest efficiency for a single-stage device. Using inductive recapture, coupling efficiencies in excess of 90% are possible; without it, the peak efficiency is much lower, η <= 55%. We conclude that inductive recapture will be required in order to achieve the high efficiency required of an electric thruster. The efficiency scales favourably with increasing power, although this does not preclude operation at lower power with acceptable efficiency. The presence of an imbedded bias flux in the slug improves the dynamic efficiency for devices without inductive recapture, but offers little improvement when used with inductive recapture.
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