Real-Time Density Control of a Plasma Source Used for Simulating Low-Earth-Orbit Plasma Environment

We developed a variable-output-aperture, laboratory plasma source to enable real-time plasma density control with minimal effect on other plasma properties. The source is capable of producing a low-Earth-orbit-type plasma with electron energies of approximately 0.1-0.7 eV and streaming ion energies of approximately 2-4 eV. The plasma density can be adjusted over two orders of magnitude, thus representing some of the natural variability of the ionosphere. In a given aperture range, the electron and ion density decreased by 73% while the average percent difference in electron and ion density was 0.3% with a standard deviation of 1.4%. The average percent difference in ion energy was 6.3% with a standard deviation of 4.3%. The variable aperture was achieved by a rotating dual-grid system.