Measurement of Plasma Presheath

The plasma presheath in a multidipole device was measured by an emissive probe using the inflection-point method in the limit of zero emission. The temporal evolution of ion-acoustic waves was also measured. Results are compared. It is shown that the potential in the bulk of the plasma is describable by a simplified version of the plasma-sheath equation. Inclusion of finite ion temperature has a negligible effect on the predicted results compared to the inclusion of the primary electrons in the theory.