Measurements of axial and horizontal thrusts in a magnetically steered radiofrequency plasma thruster*

Magnetic nozzle (MN) electrodeless plasma thrusters have been vigorously investigated as alternative options for high-power and long-lived electric propulsion devices because of the absence of the electrode exposed to plasmas, where physics studies relating to the thrust generation and improvement the thruster performances have been progressed.

When utilizing the propulsion devices to artificial satellites, a thrust vector control (TVC) technique is important for accurate control of the satellites and spacecrafts. A mechanical gimbal structure and multi-channel thrusters are often used for the TVC, resulting in the complicated structure designs for both the cases. As for an MN plasma thruster, it is expected that the thrust vector generated by the thruster can be controlled by deflecting the MN, called magnetic steering. Deflections of a supersonic ion beam and the thrust vector have been experimentally detected and numerically calculated, respectively, with no direct measurement of the thrust vector. Here we report the direct measurement of the thrust vector imparted by the MN rf plasma thruster when applying a non-axisymmetric magnetic field by mounting additional horizontal solenoids near the thruster exit, demonstrating the TVC by the magnetic steering.