An Al - water fed DC arcjet

Abstract

In this study, development of Al-water fed arcjet was conducted, in which water and aluminum were fed to the thruster as the propellant. The combustion of aluminum with water as an oxidizer can release a very high energy density with unit mass compared with fossil fuels. From the chemical equilibrium simulation, it was shown that thrust performance of the Al-water fed arcjet was as well as that of hydrazine arcjets at low specific power range. In addition, to observe behaviors of vaporized aluminum propellant fed as a solid state rod to the arcjet and then vaporized in the discharge plenum, a novel coaxial double cathode was developed and tested. It was shown that streams of vaporized aluminum were injected through the injection holes at a tip of the coaxial double cathode. From the spectroscopic measurement of the plasma in the plenum, spectra of atomic and ionic aluminum were observed at 200 nm to 400 nm. In addition, larger heat generation, probably due to exothermic chemical reactions of species, was confirmed with mixed propellant of Al and water. Since the heat exhausted from the nozzle was no longer measured after termination of discharges, this chemical reaction could be controlled only with discharges.