Patent Number: 6,293,090

Title: More efficient RF plasma electric thruster

Abstract: A radio frequency (RF) plasma thruster for use in electric propulsion forspacecraft. 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 plasmathruster compared to previous thrusters of this type, while retaining theadvantages of RF plasma thrusters over other types of electric andchemical propulsion systems.The present invention utilizes a lower hybrid wave for heating of theelectrons, rather than electron cyclotron resonance (ECR) heating. Thelower hybrid wave is used because it creates high-density plasmas and theantennas used to couple RF energy to the plasma are relatively simple toconstruct. This allows much better efficiency because no hot electronpopulation is created to siphon off much of the RF power applied to theplasma. Lower hybrid waves propagate in the frequency range between theion cyclotron frequency and the electron cyclotron frequency. The RFthruster of the present invention has a higher specific impulse thanelectrothermal thrusters, much higher power density than electrostatic ionthrusters, no life limiting grids or electrodes in contact with theplasma, and a simple geometry which is easily scaleable.

Inventors: Olson; Lynn B. (Framingham, MA)


International Classification:

Expiration Date: 09/25/2013