Thruster Concept for Transverse Acceleration by the Beating Electrostatic Waves Ponderomotive Force
A thruster concept is presented for transversely accelerating a magnetized plasma by means of the ponderomotive force that arises when a plasma mode is absorbed while propagating across a uniform magnetic field. This concept offers a number of advantages for electric propulsion including electrodeless operation and variable specific impulse. A simple slab geometry is analyzed and a general expression for thrust is presented for this concept for arbitrary plasma modes. The normalized exhaust velocity as a function of wave frequency and input power is then derived for the specific case where the ponderomotive force is provided by the absorption of two, beating electrostatic waves. It is shown that this absorption process is particularly suited for the thruster concept and yields a specific impulse that can be tuned by changing the frequency of the exciting waves. A design is presented for an annular thruster that would implement this concept with beating electrostatic waves, and it is shown that this concept can produce significant exhaust velocities that are competitive with the Hall thruster for comparable power levels.