Keywords:ion engines; optical fiber plasma; near grid plasma
Publisher:Pasadena, CA : Jet Propulsion Laboratory, National Aeronautics and Space Administration, 2004.
Citation:40th AIAA/ASME/SAE/ASEE Joint Propulsion Conference, Fort Lauderdale, Florida, July 11-14, 2004.
Abstract:
Single planar Langmuir probes and fiber optic probes are used to concurrently measure the plasma properties and neutral density variation in a 30cm diameter ion engine discharge chamber, from the immediate vicinity of the keeper to the near grid plasma region. The fiber optic probe consists of a collimated optical fiber recessed into a double bore ceramic tube fitted with a stainless steel light-limiting window. The optical fiber probe is used to measure the emission intensity of excited neutral xenon for a small volume of plasma, at various radial and axial locations. The single Langmuir probes, are used to generate current-voltage characteristics at a total of 140 spatial locations inside the discharge &amber. Assuming a maxwellian distribution for the electron population, the Langmuir probe traces provide spatially resolved measurements of plasma potential, electron temperature, and plasma density.