Abstract: A plasma thruster comprises a cylindrical discharge channel (1), an injector (4), a RF antenna surrounding the discharge channel (1) and a device (3) for generating an axial static magnetic field in the discharge channel (1). The RF antenna is a cylindrical birdcage antenna (2) formed of several electrically conductive parallel legs (10) connected by two end rings (11) including capacitors (12) between adjacent legs (10) in each case. The two end rings (11) with the capacitors (12) are formed on two printed circuit boards (14) to which the legs (10) are attached, said printed circuit boards (14) having a through opening for the discharge channel (1). The antenna maximizes electrical coupling efficiency and provides resulting electromagnetic fields for quasi-neutral plasma acceleration along with the magnetic field effect provided by the externally applied magnetic field.

Abstract: The present invention relates to a device for generating a variable angular momentum or torque, which has a container (1) partially filled with a magnetizable fluid (2) and a device for generating one or several rotating or wandering magnetic fields, with which the magnetizable fluid (2) in the container (1) can be made to continuously move on a closed orbit. The device for generating the rotating or wandering magnetic fields has several electric coils (4), whose coil axes lie in the orbital plane. This structure makes it possible to generate a variable angular momentum without mechanical moved parts or the necessity of external magnetic fields. For example, the device enables a simple and cost-effective spacecraft attitude control.