Plasma Diagnostics and Nonlinear Wave Studies with a Gridded Electrostatic Energy Analyzer

A simplified theory relating the collector current to the grid bias and other plasma parameters has been developed for a multiple-gridded electrostatic energy analyzer. Experiments have shown that the theory is only approximately valid, but the temperature obtained agrees closely with that from a Langmuir probe. It is found that temperature measurements depend on the grid bias potentials and the ratios of grid hole radius to electron Debye length. As a result, the conditions for the best performance of the energy analyzer as an accurate diagnostic device have been determined. A theory has also been worked out for the second-order change in the electron distribution function due to a cyclotron damped wave. This, together with experimental results, will provide valuable information on the thermal anisotropy of a plasma.