Determination of the Plasma Density in a Collisionless Plasma

Abstract

In place of Lam’s unified probe theory in a collisionless plasma, which is valid in the limit of ξ_e (the ratio of the probe radius to the Debye radius of the plasma)→∞, a probe theory for a finite ξ_e is developed. Some diagrams for determination of the plasma density from the positive ion current-voltage characteristics of the probe are also presented. Moreover a few kinds of experiments in a mercury diffusion plasma are carried out in order to verify the theory in rather wider condition and exemplify some applications to the theory in lower pressure plasma.