Abstract: A radio frequency (RF) plasma thruster for use in electric propulsion for spacecraft. The thruster operates by heating plasma in a magnetic field, which then flows out along magnetic field lines, producing axial thrust. The present invention greatly increases the efficiency of the RF plasma thruster compared to previous thrusters of this type, while retaining the advantages of RF plasma thrusters over other types of electric and chemical propulsion systems. The present invention utilizes a lower hybrid wave for heating of the electrons, rather than electron cyclotron resonance (ECR) heating. The lower hybrid wave is used because it creates high-density plasmas and the antennas used to couple RF energy to the plasma are relatively simple to construct. This allows much better efficiency because no hot electron population is created to siphon off much of the RF power applied to the plasma.