Retarding Field Energy Analyzer (RFEA)
An RFEA is designed to measure the Ion Velocity Distribution Function (IVDF) of a plasma. This is necessary when conducting plasma research, as was the case with the exploration of EHT's electrodeless plasma source. It functions by having a set of grids at different potentials that repel electrons and allow only ions above a certain energy through the system. Those ions with energies greater than the "discriminator" voltage (which can be varied) make contact with the back plate, resulting in a current through, and thus a voltage across, the shunt resistor. This voltage can be de-convoluted to find the IVDF.
This custom RFEA design is constructed of a tantalum housing, with a thin (1mil) polyimide sheet around the inside. A stack of polyimide insulating sheets separates charged tantalum meshes, spaced to appropriate distances. A CAD model of the RFEA can be seen at right.
Skills Demonstrated / Gained
- Developing an understanding of plasma diagnostics
- Tantalum lathing (not easy)
- Micro-machining, such as drilling through-holes for #000-120 & #00-90 screws