Effect of a Magnetic Nozzle in an MPD Thruster

Thrust imparted from a Magneto-Plasma-Dynamic thruster is directly measured by using a pendulum type thrust target and is successfully increased twice by applying a magnetic nozzle. The presently obtained thrust performance shows a thrust of ~ 6 N and a specific impulse of ~ 9000 sec for the discharge current of 6 kA. The plasma axial flow velocity is increased up to 40 km/sec near the thruster exit when increasing the magnetic nozzle field strength. Further downstream region the plasma flow is decelerated and an increase in an ion temperature is simultaneously detected. The results suggest that the axial flow energy is converted into the thermal ion energy.