Microwave plasma sources for use in space plasma physics experimentation

Summary form only given. We have developed two microwave plasma sources most useful in approximating ionospheric space plasma environments because of the low electron temperatures (<2 eV) and adjustable densities (10/sup 4/-10/sup 8/ cm/sup -3/). Both of these sources employ conventional microwave oven magnetrons and are easy to construct and exhibit stable operation over a wide range of neutral gas flow rates and electron densities. Although the production mechanism of the plasma is the same in both cases (microwave cavity resonance), the designs of the two sources are quite different. We report on the use of these types of sources in space plasma experimentation in the Space Physics Simulation Chamber (SPSC) at the Naval Research Laboratory. We will describe construction of these sources and improvements to the design, including an increased surface area to provide a more uniform plasma across the available experimental area.