Plasma Properties in the Magnetic Nozzle of an Electron Cyclotron Resonance Plasma Source
State-of-the-art electric propulsion systems use plasma discharges that require an electrode in contact with plasma. Therefore, these devices suffer from lifetime-limiting erosion processes due to the harsh plasma environment. A potential solution to this problem is the use of an electrodeless propulsion scheme, such as microwave electron cyclotron resonance (ECR). In the ECR process, electrons resonantly gain energy from the microwave field and acquire enough energy to ionize neutral gas atoms. Acceleration of ions to generate thrust can also be an electrodeless process if a magnetic nozzle is employed. We present plasma property measurements in the downstream diverging magnetic nozzle of an ECR plasma source. Results show plasma number densities as high as 1.0x10¹²cmˉ³, electron temperatures of 2-4 eV, and plasma potentials of 15-30 V. Ion energy-per-charge distributions show two peaks during low pressure operation (2.0x10ˉ⁴ Torr). The first peak corresponds with the plasma potential and represents ions falling through the plasma sheath. The second peak is attributed to an ion beam component within the plasma and has values of 30-50 V, increasing with decreasing pressure.
J. L. Rovey et al., "Plasma Properties in the Magnetic Nozzle of an Electron Cyclotron Resonance Plasma Source," Joint Propulsion Conferences, American Institute of Aeronautics and Astronautics (AIAA), Jan 2008.
The definitive version is available at http://dx.doi.org/10.2514/6.2008-5191
44th AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit
Mechanical and Aerospace Engineering
Article - Conference proceedings
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