Evaluation of Discharge Behavior of the Pulsed Plasma Thruster SIMP-LEX

The pulsed plasma thruster Add Simp-lex, developed at the IRS, was investigated at the University of Tokyo to further characterize the thruster’s performance and discharge behavior. This was done by experimental investigation of configurations with a different amount of capacitors and discrete applied voltages. To do so, a measurement system for the discharge current and the optical properties was built up and successfully applied. Further, the numerical model for the prediction of the current-normalized magnetic flux density was improved and the convergence properties of the integration towards the change in inductance studied. From the discharge current waveforms and the pictures taken from the propagating plasma, information about the amount of plasma creations, their propagation velocity and the oscillation behavior was deducted. For further characterization, the energy transfer efficiency and the electrical efficiency was derived from these data, leading to a tool to compare different configurations. It was found, that a middle voltage yields higher electrical efficiencies of about 40% whereas the energy transfer efficiency is higher the lower the applied voltage.