Probe theory - the orbital motion approach

TLDR

The orbital motion limited (OML) theory of cylindrical and spherical Langmuir probes is reviewed, highlighting its widespread use. Extensive numerical extensions to the Bohm–Burhop–Massey orbital motion theory are briefly discussed. The OML theory is found to be invalid in many cases, and the Bohm–Burhop–Massey theory introduces an absorption radius to resolve this.

Abstract

A review is given of the orbital motion limited (O.M.L.) theory of cylindrical and spherical Langmuir probes. In many cases the O.M.L. theory is invalid and the second orbital motion theory presented here, that of Bohm, Burhop and Massey, shows that the concept of an absorption radius must be introduced. The extensive numerical extensions to this theory are briefly discussed.