Generation of the Magnetic Null Field Topography in a Novel Electric Propulsion Proof-of-Concept

Abstract

An experimental device to prove the feasibility of a novel plasma propulsion concept utilizing beating electrostatic waves to accelerate ions in a polarity-reversing rectilinear magnetic field is designed, built, and tested. The electromagnetic coils in the device are designed around criteria determined by the ion dynamics. The magnetic field generated is shown to closely match its proposed profile used in ear- lier experiment-qualifying simulations of the thruster’s ion dynamics. Due to its Helmholtz-like geometry, the device may be scaled linearly without affecting the field topography or the absolute size of the magnetic reversal. A specific definition of field uniformity is drawn and used to revise the mathematical construction of the field topography with a new scaling parameter σ to recreate a high-fidelity profile with any desired magnetic reversal size. Simulations using both this construct and the measured field of the device indicate a positive relation between performance and relative size of the thruster chamber to ion gyroradius, determined by magnetization or device scale. Two experimental attempts at measuring an ion current exiting the thruster fail due to massive wall losses inside the chamber, lending credence to the simulations showing poor performance in small thruster sizes.