Experimental Investigation of Steady-State Applied-Field Magnetoplasmadynamic Thrusters at Institute of Space Systems

摘要

The applied-field magnetoplasmadynamic thruster AF-MPD ZT1 was successfully put in operation at IRS. The thruster operated in steady-state mode with Argon as propellant at low electric arc power of 6 kW. Discharge voltage and power increased as expected almost linear with applied magnetic flux density. The variation of mass flow rate ratio between anode and cathode gas towards higher cathode gas fraction showed increasing thrust and thrust efficiency at applied magnetic flux density of 0.1 T and are comparable with DLR's X13 thruster. Additionally a steady-state 100 kW AF-MPD thruster SX3 was developed, set in operation and preliminary characterized at IRS. The SX3 thruster was operated at relatively low arc powers up to 30 kW and applied magnetic flux density of 0.1 T generated by the modified ZT coil. Due to low arc current and magnetic flux level, the AF-MPD ZT1 thruster achieved thrust of 70 mN and exhaust velocity up to 10 km/s at 6 kW arc power and up to 6 % thrust efficiency. The SX3 thruster reached thrust of 362 mN and thrust efficiency more than 12 % in steady state-operation at 25 kW arc power and at applied magnetic flux density of 0.1 T. However both thrusters have been operated at limited magnetic fluxes only. For SX3 a total operation time of more than 3600 s together with 30 ignitions could be accumulated. The electrodes, however, do not show significant erosion nor a respective degradation. The performances of thrusters provide an outlook for future investigations on AF-MPD thrusters at IRS and give a hint to improvement in thrust efficiency of presented devices with the new applied-field coil, which will be manufactured in the future to produce magnetic flux densities up to 0.6 T allowing further increase in thrust efficiency up to 30 %.